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Sample records for based mimo channel

  1. Belief Propagation based MIMO Detection Operating on Quantized Channel Output

    CERN Document Server

    Mezghani, Amine

    2010-01-01

    In multiple-antenna communications, as bandwidth and modulation order increase, system components must work with demanding tolerances. In particular, high resolution and high sampling rate analog-to-digital converters (ADCs) are often prohibitively challenging to design. Therefore ADCs for such applications should be low-resolution. This paper provides new insights into the problem of optimal signal detection based on quantized received signals for multiple-input multiple-output (MIMO) channels. It capitalizes on previous works which extensively analyzed the unquantized linear vector channel using graphical inference methods. In particular, a "loopy" belief propagation-like (BP) MIMO detection algorithm, operating on quantized data with low complexity, is proposed. In addition, we study the impact of finite receiver resolution in fading channels in the large-system limit by means of a state evolution analysis of the BP algorithm, which refers to the limit where the number of transmit and receive antennas go t...

  2. Bidirectional MIMO Channel Tracking Based on PASTd and Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Shayevitz Ofer

    2010-01-01

    Full Text Available Abstract We consider a bidirectional time division duplex (TDD multiple-input multiple-output (MIMO communication system with time-varying channel and additive white Gaussian noise (AWGN. A blind bidirectional channel tracking algorithm, based on the projection approximation subspace tracking (PAST algorithm, is applied in both terminals. The resulting singular value decomposition (SVD of the channel matrix is then used to approximately diagonalize the channel. The proposed method is applied to an orthogonal frequency-division multiplexing-(OFDM-MIMO setting with a typical indoor time-domain reflection model. The computational cost of the proposed algorithm, compared with other state-of-the-art algorithms, is relatively small. The Kalman filter is utilized for establishing a benchmark for the obtained performance of the proposed tracking algorithm. The performance degradation relative to a full channel state information (CSI due to the application of the tracking algorithm is evaluated in terms of average effective rate and the outage probability and compared with alternative tracking algorithms. The obtained results are also compared with a benchmark obtained by the Kalman filter with known input signal and channel characteristics. It is shown that the expected degradation in performance of frequency-domain algorithms (which do not exploit the smooth frequency response of the channel is only minor compared with time-domain algorithms in a range of reasonable signal-to-noise ratio (SNR levels. The proposed bidirectional frequency-domain tracking algorithm, proposed in this paper, is shown to attain communication rates close to the benchmark and to outperform a competing algorithm. The paper is concluded by evaluating the proposed blind tracking method in terms of the outage probability and the symbol error rate (SER versus. SNR for binary phase shift keying (BPSK and 4-Quadrature amplitude modulation (QAM constellations.

  3. Characteristic Analysis on UAV-MIMO Channel Based on Normalized Correlation Matrix

    OpenAIRE

    Gao Xi jun; Chen Zi li; Hu Yong Jiang

    2014-01-01

    Based on the three-dimensional GBSBCM (geometrically based double bounce cylinder model) channel model of MIMO for unmanned aerial vehicle (UAV), the simple form of UAV space-time-frequency channel correlation function which includes the LOS, SPE, and DIF components is presented. By the methods of channel matrix decomposition and coefficient normalization, the analytic formula of UAV-MIMO normalized correlation matrix is deduced. This formula can be used directly to analyze the condition numb...

  4. Codebook-based interference alignment for uplink MIMO interference channels

    KAUST Repository

    Lee, Hyun Ho

    2014-02-01

    In this paper, we propose a codebook-based interference alignment (IA) scheme in the constant multiple-input multipleoutput (MIMO) interference channel especially for the uplink scenario. In our proposed scheme, we assume cooperation among base stations (BSs) through reliable backhaul links so that global channel knowledge is available for all BSs, which enables BS to compute the transmit precoder and inform its quantized index to the associated user via limited rate feedback link.We present an upper bound on the rate loss of the proposed scheme and derive the scaling law of the feedback load tomaintain a constant rate loss relative to IA with perfect channel knowledge. Considering the impact of overhead due to training, cooperation, and feedback, we address the effective degrees of freedom (DOF) of the proposed scheme and derive the maximization of the effective DOF. From simulation results, we verify our analysis on the scaling law to preserve the multiplexing gain and confirm that the proposed scheme is more effective than the conventional IA scheme in terms of the effective DOF. © 2014 KICS.

  5. MIMO-DFE BASED SPACE-TIME RECEIVER OVER FREQUENCY SELECTIVE CHANNELS WITH LIMITED ERROR PROPAGATION

    Institute of Scientific and Technical Information of China (English)

    Shen Liyun; Hu Bo

    2005-01-01

    MIMO-DFE(Multiple-Input-Multiple-Output Decision Feedback Equalizer) based receiver architectures are researched recently to detect signals in BLAST(Bell laboratories LAyered Space-Time) over frequency-selective channels. Due to their recursive structure, these receivers may suffer from error propagation which results in an overall mean square error degradation. An MIMO-DFE based BLAST receiver with limited error propagation to combat frequencyselective channel is proposed, which employs both norm constraint on feedback filter taps and soft decision device. Simulation results show that the proposed receiver outperforms conventional ones in various frequency selective channels.

  6. EVALUATION OF BER FOR VARIOUS FADING CHANNEL IN DWT BASED MIMO-OFDM SYSTEM

    Directory of Open Access Journals (Sweden)

    D. Meenakshi

    2013-04-01

    Full Text Available MIMO communication is mainly use in the OFDM to improve the communication performance and capacity. DWT based MIMO-OFDM is used in this paper. Compare to the FFT based MIMO-OFDM it has lot advantages. There is no need for cyclic prefix, flexibility and optimal resolution. Ripple(Wavelet concept has developed as a fresh scientific implement with the aim of preserve be functional in several applications such as processing of image, biomedical manufacturing, radar, physics, organize systems also message systems. The essential region of purpose of ripples in communication system: numerous accesses. A fresh modulation/multiplexing scheme consuming ripple transform remained planned for (3rd production organization project 3GPP systems. This fresh modulation system implemented in (orthogonal frequency division multiplexing OFDM scheme in addition to conventional based(FFT transform blocks is replaced by wavelet transform blocks. There are many multiplicity of ripple transforms are offered, out of which four were chosen. They are Haar, Daubechies, Bi-orthogonal and reverse Bi-orthogonal transforms. Haar wavelet is best one of among all types of wavelet. The performance of DWT based MIMO-OFDM is calculated by bit error rate (BER in various channel that is AWGN channel and Rayleigh channel. Using MATLAB-Simulation which channel is best for the DWT based MIMO-OFDM.

  7. Optimal Power Allocation for GSVD-Based Beamforming in the MIMO Wiretap Channel

    CERN Document Server

    Fakoorian, S Ali A

    2010-01-01

    This paper considers a multiple-input multiple-output (MIMO) Gaussian wiretap channel model, where there exists a transmitter, a legitimate receiver and an eavesdropper, each equipped with multiple antennas. Perfect secrecy is achieved when the transmitter and the legitimate receiver can communicate at some positive rate, while ensuring that the eavesdropper gets zero bits of information. In this paper, the perfect secrecy capacity of the multiple antenna MIMO wiretap channel is found for aribtrary numbers of antennas under the assumption that the transmitter performs beamforming based on the generalized singular value decomposition (GSVD). More precisely, the optimal allocation of power for the GSVD-based precoder that achieves the secrecy capacity is derived. This solution is shown to have several advantages over prior work that considered secrecy capacity for the general MIMO Gaussian wiretap channel under a high SNR assumption. Numerical results are presented to illustrate the proposed theoretical finding...

  8. Performance of Adaptive Subchannel Assignment-Based MIMO/OFDM Systems over Multipath Fading Channels

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Adaptive antenna arrays at both the base and mobile stations can further increase system capacity and improve the quality of service of conventional orthogonal frequency division multiplexing (OFDM) systems. Conventional adaptive antenna array-based multiple-input multiple-output (MIMO)/OFDM systems use the sub-carriers characterized by the largest eigenvalue to transmit the OFDM symbols. This paper describes the performance of adaptive subchannel assignment-based MIMO/OFDM systems over multipath fading channels. The system adaptively selects the eigenvectors associated with the relatively large subchannel eigenvalues to generate the antenna array weights at the base and mobile stations and then adaptively assigns the corresponding best subchannels to transmit the OFDM symbols. Simulation results show that the proposed system can achieve better performance than the conventional adaptive antenna array-based MIMO/OFDM system over multipath fading channels.

  9. A Leakage-Based MMSE Beamforming Design for a MIMO Interference Channel

    DEFF Research Database (Denmark)

    Sun, Fan; De Carvalho, Elisabeth

    2012-01-01

    We propose a low complexity design of the linear transmit filters for a MIMO interference channel. This design is based on a minimum mean squared error (MMSE) approach incorporating the signal and the interference leakage for each transmitter. Unlike the previous methods, it allows a closed...

  10. Cross-Layer Optimization of MIMO-Based Mesh Networks with Gaussian Vector Broadcast Channels

    CERN Document Server

    Liu, Jia

    2007-01-01

    MIMO technology is one of the most significant advances in the past decade to increase channel capacity and has a great potential to improve network capacity for mesh networks. In a MIMO-based mesh network, the links outgoing from each node sharing the common communication spectrum can be modeled as a Gaussian vector broadcast channel. Recently, researchers showed that ``dirty paper coding'' (DPC) is the optimal transmission strategy for Gaussian vector broadcast channels. So far, there has been little study on how this fundamental result will impact the cross-layer design for MIMO-based mesh networks. To fill this gap, we consider the problem of jointly optimizing DPC power allocation in the link layer at each node and multihop/multipath routing in a MIMO-based mesh networks. It turns out that this optimization problem is a very challenging non-convex problem. To address this difficulty, we transform the original problem to an equivalent problem by exploiting the channel duality. For the transformed problem,...

  11. A Fractional Lower Order Statistics-Based MIMO Detection Method in Impulse Noise for Power Line Channel

    Directory of Open Access Journals (Sweden)

    CHEN, Z.

    2014-11-01

    Full Text Available Impulse noise in power line communication (PLC channel seriously degrades the performance of Multiple-Input Multiple-Output (MIMO system. To remedy this problem, a MIMO detection method based on fractional lower order statistics (FLOS for PLC channel with impulse noise is proposed in this paper. The alpha stable distribution is used to model impulse noise, and FLOS is applied to construct the criteria of MIMO detection. Then the optimal detection solution is obtained by recursive least squares algorithm. Finally, the transmitted signals in PLC MIMO system are restored with the obtained detection matrix. The proposed method does not require channel estimation and has low computational complexity. The simulation results show that the proposed method has a better PLC MIMO detection performance than the existing ones under impulsive noise environment.

  12. Performance Evaluation of Closed-Loop Spatial Multiplexing Codebook Based on Indoor MIMO Channel Measurement

    Directory of Open Access Journals (Sweden)

    Junjun Gao

    2012-01-01

    Full Text Available Closed-loop MIMO technique standardized in LTE can support different layer transmissions through precoding operation to match the channel multiplexing capability. However, the performance of the limited size codebook still needs to be evaluated in real channel environment for further insights. Based on the wideband MIMO channel measurement in a typical indoor scenario, capacity loss (CL of the limited size codebook relative to perfect precoding is studied first in two extreme channel conditions. The results show that current codebook design for single layer transmission is nearly capacity lossless, and the CL will increase with the number of transmitted layers. Furthermore, the capacity improvement of better codebook selection criterions is very limited compared to CL. Then we define the maximum capacity boost achieved by frequency domain layer adaption (FDLA and investigate its sensitivity to SNR and channel condition. To survey the effect of frequency domain channel variation on MIMO-OFDM system, we define a function to measure the fluctuation levels of the key channel metrics within a subband and reveal the inherent relationship between them. Finally, a capacity floor resulted as the feedback interval increases in frequency domain.

  13. Measurements of MIMO Indoor Channels at 1800 MHz with Multiple Indoor and Outdoor Base Stations

    Directory of Open Access Journals (Sweden)

    Jaldén Niklas

    2007-01-01

    Full Text Available This paper proposes several configurations for multiple base stations in indoor MIMO systems and compares their performance. The results are based on channel measurements realized with a MIMO testbed. The receiver was moved along several routes and floors on an office building. Both outdoor and indoor locations are considered for the transmitters or base stations, which allow the analysis of not only indoor but also outdoor-to-indoor environment. The use of 2 base stations with different system level combinations of the two is analyzed. We show that the configuration with base station selection provides almost as good performance as a full water-filling scheme when the 2 base stations are placed at different locations. Also the spatial correlation properties for the different configurations are analyzed and the importance of considering path loss when evaluating capacity is highlighted.

  14. Low-Complexity Geometry-Based MIMO Channel Simulation

    Directory of Open Access Journals (Sweden)

    Christoph W. Ueberhuber

    2007-01-01

    Full Text Available The simulation of electromagnetic wave propagation in time-variant wideband multiple-input multiple-output mobile radio channels using a geometry-based channel model (GCM is computationally expensive. Due to multipath propagation, a large number of complex exponentials must be evaluated and summed up. We present a low-complexity algorithm for the implementation of a GCM on a hardware channel simulator. Our algorithm takes advantage of the limited numerical precision of the channel simulator by using a truncated subspace representation of the channel transfer function based on multidimensional discrete prolate spheroidal (DPS sequences. The DPS subspace representation offers two advantages. Firstly, only a small subspace dimension is required to achieve the numerical accuracy of the hardware channel simulator. Secondly, the computational complexity of the subspace representation is independent of the number of multipath components (MPCs. Moreover, we present an algorithm for the projection of each MPC onto the DPS subspace in 𝒪(1 operations. Thus the computational complexity of the DPS subspace algorithm compared to a conventional implementation is reduced by more than one order of magnitude on a hardware channel simulator with 14-bit precision.

  15. Maximizing Channel Capacity based on Antenna and MIMO Channel Characteristics and its Application to Multimedia Data Transmission

    Science.gov (United States)

    Pottkotter, Andrew

    Communication transmission between electronic devices is evolving at an ever faster pace. There are now more electronic handheld devices that we communicate with on a daily basis. The allotted bandwidth and speed for these devices are limited by hardware, software, handshaking capabilities between each electronic application. The demand for information at high data rates without the loss of reliability has evolved antenna technology and digital signal processing into more complex systems utilizing multiple processors and multiple antennas. This paper discusses the various techniques used to increase data speed, enhance channel capacity, and reliability of application specific devices with respect to the Multiple-Input-to-Multiple-Output (MIMO) based methods. MIMO based applications can improve the data speed, channel capacity, and reliability of the system with maximum limitations based on hardware, coding schemes, and handshaking abilities between devices.

  16. Channel Verification Results for the SCME models in a Multi-Probe Based MIMO OTA Setup

    DEFF Research Database (Denmark)

    Fan, Wei; Carreño, Xavier; S. Ashta, Jagjit; Nielsen, Jesper Ødum; Pedersen, Gert Frølund; B. Knudsen, Mikael

    MIMO OTA testing methodologies are being intensively investigated by CTIA and 3GPP, where various MIMO test methods have been proposed which vary widely in how they emulate the propagation channels. Inter-lab/inter-technique OTA performance comparison testing for MIMO devices is ongoing in CTIA......, where the focus is on comparing results from various proposed methods. Channel model verification is necessary to ensure that the target channel models are correctly implemented inside the test area. This paper shows that the all the key parameters of the SCME models, i.e., power delay profile, temporal...

  17. A 3D Geometry-based Stochastic Model for 5G Massive MIMO Channels

    Directory of Open Access Journals (Sweden)

    Yi Xie

    2015-09-01

    Full Text Available Massive MIMO is one of the most promising technologies for the fifth generation (5G mobile communication systems. In order to better assess the system performance, it is essential to build a corresponding channel model accurately. In this paper, a three-dimension (3D two-cylinder regular-shaped geometry-based stochastic model (GBSM for non-isotropic scattering massive MIMO channels is proposed. Based on geometric method, all the scatters are distributed on the surface of a cylinder as equivalent scatters. Non-stationary property is that one antenna has its own visible area of scatters by using a virtual sphere. The proposed channel model is evaluated by comparing with the 3GPP 3D channel model [1]. The statistical properties are investigated. Simulation results show that close agreements are achieved between the characteristics of the proposed channel model and those of the 3GPP channel model, which justify the correctness of the proposed model. The model has advantages such as good applicability.

  18. Performance of VBLAST Systems Based on Spatial Correlated MIMO Channels

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-peng; QIU Zhong-yuan; WU Wei-ling

    2004-01-01

    Vertically-layered Bell Laboratories Layered Space-Time (VBLAST) is one of the most promising techniques for realizing high spectral efficiencies over wireless link. In previously published work, the performance of VBLAST has been primarily investigated in uncorrelated Rayleigh fading channels. However in real environments some correlation between antenna elements can be presented. In this paper, we study the impact of transmit correlation on the performance of VBLAST systems. Finally we provide simulation results demonstrating the impact of spatial fading correlation on the symbol error rate of VBLAST.

  19. MIMO Channel Capacity for Handsets in Data Mode Operation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Yanakiev, Boyan; Bonev, Ivan Bonev;

    2010-01-01

    The current paper concerns realistic evaluation of the capacity of the MIMO channel between a BS and handheld device, such as a PDA or smart phone, held in front of the user’s body (data mode). The work is based on measurements of the MIMO channel between two widely separated BSs in a micro...

  20. Channel Statistics for MIMO Handsets in Data Mode

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Yanakiev, Boyan; Barrio, Samantha Caporal Del; Pedersen, Gert Frølund

    The presented work is based on a large dual- band, dual-base outdoor-to-indoor multiple-input multiple- output (MIMO) channel measurement campaign, involving ten different realistic MIMO handsets, held in data mode by eight test users. Various different use cases (UCs) are measured. Statistics on...

  1. Modified MIMO Cube for Enhanced Channel Capacity

    Directory of Open Access Journals (Sweden)

    Lajos Nagy

    2012-01-01

    Full Text Available This paper deals with the optimization of MIMO antenna elements' position in modified MIMO cube for getting maximal channel capacity in indoor environment. The dependence of the channel capacity on the antenna orientation was analyzed by simulations. We have also examined the effect of the frequency dependence of the antenna system (in case of conjugate matching and nonconjugate matching for the channel capacity. Based on the simulation results in the created and measured antenna system, the antennas were at a right angle to each other. At the two chosen different structures, we measured the antenna parameters and the channel capacity. In this paper, we present the results of the measurements which clearly confirm our simulations. We will point out the differences between the two antenna structures.

  2. Practical guide to MIMO radio channel with MATLAB examples

    CERN Document Server

    Brown, Tim; De Carvalho, Elizabeth

    2012-01-01

    This book provides an excellent reference to the MIMO radio channel In this book, the authors introduce the concept of the Multiple Input Multiple Output (MIMO) radio channel, which is an intelligent communication method based upon using multiple antennas. Moreover, the authors provide a summary of the current channel modeling approaches used by industry, academia, and standardisation bodies. Furthermore, the book is structured to allow the reader to easily progress through the chapters in order to gain an understanding of the fundamental and mathematical principles behind MIMO. It al

  3. Mi-MMAC: MIMO-Based Multi-Channel MAC Protocol for WLAN

    Directory of Open Access Journals (Sweden)

    Bo Yang

    2015-11-01

    Full Text Available In order to meet the proliferating demands in wireless local area networks (WLANs, the multi-channel media access control (MMAC technology has attracted a considerable attention to exploit the increasingly scarce spectrum resources more efficiently. This paper proposes a novel multi-channel MAC to resolve the congestion on the control channel, named as Mi-MMAC, by multiplexing the control-radio and the data-radio as a multiple-input multiple-output (MIMO array, working on both the control channel and the data channels alternately. Furthermore, we model Mi-MMAC as an M/M/k queueing system and obtain a closed-form approximate formula of the saturation throughput. Simulation results validate our model and analysis, and we demonstrate that the saturation throughput gain of the proposed protocol is close to 3.3 times compared with the dynamical channel assignment (DCA protocol [1] under the few collisions condition.

  4. Mimo Based Downlink Channels with Limited Feedback and User Selection Using Th Precoding Technique

    Directory of Open Access Journals (Sweden)

    B.Muralidharan

    2014-03-01

    Full Text Available The implementation of Tomlinson-Harashima (TH pre-coding for multiuser MIMO systems based on quantized channel state information (CSI at the transmitter side. Compared with the results in [1], our scheme applies to more general system setting where the number of users in the system can be less than or equal to the number of transmit antennas. We also study the achievable average sum rate of the proposed quantized CSI-based TH pre-coding scheme. The expressions of the upper bounds on both the average sum rate of the systems with quantized CSI and the mean loss in average sum rate due to CSI quantization are derived. We also present some numerical results. The results show that the nonlinear TH pre-coding can achieve much better performance than that of linear zero-forcing pre-coding for both perfect CSI and quantized CSI cases. In addition, our derived upper bound on the mean rate loss for TH pre-coding converges to the true rate loss faster than that of zero-forcing pre-coding obtained in [2] as the number of feedback bits becomes large. Both the analytical and numerical results show that nonlinear pre-coding suffers from imperfect CSI more than linear pre-coding does.

  5. Design of Wideband MIMO Car-to-Car Channel Models Based on the Geometrical Street Scattering Model

    Directory of Open Access Journals (Sweden)

    Nurilla Avazov

    2012-01-01

    Full Text Available We propose a wideband multiple-input multiple-output (MIMO car-to-car (C2C channel model based on the geometrical street scattering model. Starting from the geometrical model, a MIMO reference channel model is derived under the assumption of single-bounce scattering in line-of-sight (LOS and non-LOS (NLOS propagation environments. The proposed channel model assumes an infinite number of scatterers, which are uniformly distributed in two rectangular areas located on both sides of the street. Analytical solutions are presented for the space-time-frequency cross-correlation function (STF-CCF, the two-dimensional (2D space CCF, the time-frequency CCF (TF-CCF, the temporal autocorrelation function (ACF, and the frequency correlation function (FCF. An efficient sum-of-cisoids (SOCs channel simulator is derived from the reference model. It is shown that the temporal ACF and the FCF of the SOC channel simulator fit very well to the corresponding correlation functions of the reference model. To validate the proposed channel model, the mean Doppler shift and the Doppler spread of the reference model have been matched to real-world measurement data. The comparison results demonstrate an excellent agreement between theory and measurements, which confirms the validity of the derived reference model. The proposed geometry-based channel simulator allows us to study the effect of nearby street scatterers on the performance of C2C communication systems.

  6. Performance comparison of wavelet denoising based fast DOA estimation of MIMO OFDM system over Rayleigh Fading Channel

    Directory of Open Access Journals (Sweden)

    A.V.Meenakshi

    2012-09-01

    Full Text Available This paper presents a tool for the analysis, and simulation of direction-of-arrival estimation for MIMO OFDM signal over the Rayleigh fading channel. The performance of the proposed technique is tested for wavelet denoising based CYCLIC MUSIC algorithm. Simulation results demonstrate that the proposed system not only has good ability of suppressing interference, but also significantly improves the DOA estimation of the system. In this paper, it is proposed to find DOA of the received MIMO OFDM signal, and the performances are analyzed using matlab simulation by the Monte Carlo computer iteration. This paper provides a fairly complete image of the performance and statistical efficiency with QPSK signal model for coherent system at a lower SNR(18dB and interference environment.

  7. Covariance-based Spatial Channel Structure Emulation for MIMO OTA Testing

    DEFF Research Database (Denmark)

    Tsakalaki, Elpiniki; Alrabadi, Osama; Fan, Wei;

    2014-01-01

    The paper presents a general framework for recreating the spatial channel structure in a MIMO over-the-air (OTA) multiprobe anechoic chamber testing setup. The idea is to find the power weights of the spatial taps (antenna probes) that minimize a certain distance between the spatial channel...... covariance matrix corresponding to the desired (continuous) channel and the covariance related to the emulated (discrete) channel within the test area. Unlike previous methods that merely rely on the spatial correlation coefficient, the proposed approach properly accounts for emulating the power imbalance...... among the antennas-under-test by considering the whole spatial covariance structure. The simulation results validate the improved performance of the suggested approach in terms of emulation accuracy compared to the key emulation methods proposed in the literature....

  8. A Novel Pilot Expansion Approach for MIMO Channel Estimation

    Directory of Open Access Journals (Sweden)

    Ming Fei SIYAU

    2015-05-01

    Full Text Available A training-based MIMO channel estimation scheme is presented to operate in severe frequency and time selective fading channels. Besides the new pilot bits designed from the ‘Paley-Hadamard’ matrix to exploit its orthogonal and ‘Toeplitz-like’ structures and minimising its pilot length, a novel pilot expansion technique is proposed to estimate the length of the channel impulse response, by flexibly extending its pilot length as required in order to capture the number of multipath existed within the MIMO channel. The pilot expansion can also help to deduce the initial channel variation and its Doppler rate which can be subsequently applied for MIMO channel tracking using decision feedback Kalman filter during the data payload.

  9. Indoor MIMO Channel Measurement and Modeling

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Andersen, Jørgen Bach

    2005-01-01

    Forming accurate models of the multiple input multiple output (MIMO) channel is essential both for simulation as well as understanding of the basic properties of the channel. This paper investigates different known models using measurements obtained with a 16x32 MIMO channel sounder for the 5.8GHz...... accurate model for Gaussian channels. For each of the environments different sizes of both the transmitter and receiver antenna arrays are investigated, 2x2 up to 16x32. Generally it was found that in terms of capacity cumulative distribution functions (CDFs) all models fit well for small array sizes, but...

  10. A Perspective on the MIMO Wiretap Channel

    KAUST Repository

    Oggier, Frederique

    2015-10-01

    A wiretap channel is a communication channel between a transmitter Alice and a legitimate receiver Bob, in the presence of an eavesdropper Eve. The goal of communication is to achieve reliability between Alice and Bob, but also confidentiality despite Eve’s presence. Wiretap channels are declined in all kinds of flavors, depending on the underlying channels used by the three players: discrete memoryless channels, additive Gaussian noise channels, or fading channels, to name a few. In this survey, we focus on the case where the three players use multiple-antenna channels with Gaussian noise to communicate. After summarizing known results for multiple-input–multiple-output (MIMO) channels, both in terms of achievable reliable data rate (capacity) and code design, we introduce the MIMO wiretap channel. We then state the MIMO wiretap capacity, summarize the idea of the proof(s) behind this result, and comment on the insights given by the proofs on the physical meaning of the secrecy capacity. We finally discuss design criteria for MIMO wiretap codes.

  11. Relationship Between Capacity and Pathloss for Indoor MIMO Channels

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Andersen, Jørgen Bach; Bauch, Gerhard;

    2006-01-01

    MIMO transmission systems exploit scattering in the radio channel to achieve high capacity for a given SNR. A high pathloss is generally expected for channels with rich scattering, suggesting that a high SNR and rich multipath are competing goals. The current work investigates this issue based on...

  12. SAGE based iterative receiver for joint synchronization and channel estimation in uplink MIMO-OFDMA systems

    Institute of Scientific and Technical Information of China (English)

    JIANG Zheng; QIN Xiao-fang; ZHANG Xin; CHANG Yong-yu

    2008-01-01

    A new Turbo iterative receiver structure is proposed for the uplink multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) systems. The space-alternating generalized expectation-maximization (SAGE) algorithm is naturally embedded in the framework of iterative receiver to perform synchronization and detection using the Turbo detector outputs. In each iteration, the expectation step intends to remove the multiple access interference (MAI) caused by other asynchronous users, and the maximization step is utilized to estimate the required parameters (i.e., timing offset, carrier frequency offset, channel state information, etc.) sequentially for each user. Simulation results show that the proposed algorithm can approach the performance of ideal receiver closely, while the processing complexity is rather lower than the conventional detectors.

  13. Compressive Sensing for Feedback Reduction in MIMO Broadcast Channels

    OpenAIRE

    Qaseem, Syed T.; Al-Naffouri, Tareq Y.

    2009-01-01

    We propose a generalized feedback model and compressive sensing based opportunistic feedback schemes for feedback resource reduction in MIMO Broadcast Channels under the assumption that both uplink and downlink channels undergo block Rayleigh fading. Feedback resources are shared and are opportunistically accessed by users who are strong, i.e. users whose channel quality information is above a certain fixed threshold. Strong users send same feedback information on all shared channels. They ar...

  14. Antenna Subset Selection for Cyclic Prefix Assisted MIMO Wireless Communications over Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    T. Kaiser

    2008-04-01

    Full Text Available Antenna (subset selection techniques are feasible to reduce the hardware complexity of multiple-input multiple-output (MIMO systems, while keeping the benefits of higher-order MIMO systems. Many studies of antenna selection schemes are based on frequency-flat channel models, which are inconsistent to broadband MIMO systems employing spatial-multiplexing. In broadband MIMO systems aiming to provide high-data-rate links, the employed signal bandwidth is typically larger than the coherence bandwidth of the channel so that the channel will be of frequency selective nature. Within this contribution we provide an overview on joint transmitter- and receiver-side antenna subset selection methods for frequency selective channels and deploy them in MIMO orthogonal frequency division multiplexing (OFDM systems and MIMO single-carrier (SC systems employing frequency domain equalization (FDE.

  15. Semiparametric theory based MIMO model and performance analysis

    Institute of Scientific and Technical Information of China (English)

    XU Fang-min; XU Xiao-dong; ZHANG Ping

    2007-01-01

    In this article, a new approach for modeling multi- input multi-output (MIMO) systems with unknown nonlinear interference is introduced. The semiparametric theory based MIMO model is established, and Kernel estimation is applied to combat the nonlinear interference. Furthermore, we derive MIMO capacity for these systems and explore the asymptotic properties of the new channel matrix via theoretical analysis. The simulation results show that the semiparametric theory based modeling and kernel estimation are valid to combat this kind of interference.

  16. Rateless Coding for MIMO Block Fading Channels

    CERN Document Server

    Fan, Yijia; Erkip, Elza; Poor, H Vincent

    2008-01-01

    In this paper the performance limits and design principles of rateless codes over fading channels are studied. The diversity-multiplexing tradeoff (DMT) is used to analyze the system performance for all possible transmission rates. It is revealed from the analysis that the design of such rateless codes follows the design principle of approximately universal codes for parallel multiple-input multiple-output (MIMO) channels, in which each sub-channel is a MIMO channel. More specifically, it is shown that for a single-input single-output (SISO) channel, the previously developed permutation codes of unit length for parallel channels having rate LR can be transformed directly into rateless codes of length L having multiple rate levels (R, 2R, . . ., LR), to achieve the DMT performance limit.

  17. Small Terminal MIMO Channels with User Interaction

    DEFF Research Database (Denmark)

    Pedersen, Gert Frølund; Andersen, Jørgen Bach; Eggers, Patrick Claus F.;

    2007-01-01

    This paper gives an overview of results obtained from measurements of different types of multiple-input multiple-output (MIMO) channels. For the indoor case measurements were made at 5.8 GHz from access points (APs) to mobile stations (MSs) at different places in a large open office type room...

  18. User Influence on MIMO Channel Capacity for Handsets in Data Mode Operation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Yanakiev, Boyan Radkov; Bonev, Ivan Bonev; Christensen, Morten; Pedersen, Gert Frølund

    2012-01-01

    The current paper concerns realistic evaluation of the capacity of the MIMO channel between a BS and handheld device, such as a PDA or smartphone, held in front of the user’s body (data mode). The work is based on measurements of the MIMO channel between two widely separated BSs in a micro...

  19. Optimization of Training Signal Transmission for Estimating MIMO Channel under Antenna Mutual Coupling Conditions

    Directory of Open Access Journals (Sweden)

    Xia Liu

    2010-01-01

    Full Text Available This paper reports investigations on the effect of antenna mutual coupling on performance of training-based Multiple-Input Multiple-Output (MIMO channel estimation. The influence of mutual coupling is assessed for two training-based channel estimation methods, Scaled Least Square (SLS and Minimum Mean Square Error (MMSE. It is shown that the accuracy of MIMO channel estimation is governed by the sum of eigenvalues of channel correlation matrix which in turn is influenced by the mutual coupling in transmitting and receiving array antennas. A water-filling-based procedure is proposed to optimize the training signal transmission to minimize the MIMO channel estimation errors.

  20. Estimation of Sparse MIMO Channels with Common Support

    CERN Document Server

    Barbotin, Yann; Rangan, Sundeep; Vetterli, Martin

    2011-01-01

    We consider the problem of estimating sparse communication channels in the MIMO context. In small to medium bandwidth communications, as in the current standards for OFDM and CDMA communication systems (with bandwidth up to 20 MHz), such channels are individually sparse and at the same time share a common support set. Since the underlying physical channels are inherently continuous-time, we propose a parametric sparse estimation technique based on finite rate of innovation (FRI) principles. Parametric estimation is especially relevant to MIMO communications as it allows for a robust estimation and concise description of the channels. The core of the algorithm is a generalization of conventional spectral estimation methods to multiple input signals with common support. We show the application of our technique for channel estimation in OFDM (uniformly/contiguous DFT pilots) and CDMA downlink (Walsh-Hadamard coded schemes). In the presence of additive white Gaussian noise, theoretical lower bounds on the estimat...

  1. Hybrid Transmission Scheme for MIMO Relay Channels

    Directory of Open Access Journals (Sweden)

    Guangming Xu

    2009-11-01

    Full Text Available To improve the achievable rate for the MIMO channels, we propose a hybrid transmission (HT scheme that mixes half-duplex decode-and-forward cooperative relaying transmission (DFRH)with direct transmission (DT. In the HT scheme, the source message is divided into two parts: one is transmitted by DFRH scheme and another is transmitted by DT scheme. Precoding and decoding are considered to convert the original MIMO relay channel into several parallel subchannels so that resource allocation can be easily performed. We focus on the spatial subchannel and power allocation problem. The objective of this problem is to maximize the total achievable rate under the constraints of joint total transmission power. Simulation results show that significant capacity gain can be achieved by the HT scheme compared to the DT scheme and the pure DFRH scheme.

  2. VARIABLE-RATE MULTIUSER DIVERSITY IN CORRELATED MIMO CHANNEL VIA VIRTUAL CHANNEL REPRESENTATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper studies the multiuser diversity with constellation selection based on a virtual representation of realistic Multiple Input Multiple Output (MIMO) correlated channels. To realize multiuser diversity in slow fading channels, random beamforming is adopted. Random beamforming matrix exploiting virtual channel representation is constructed, which can match the channel matrix of the desired user better. Simultaneously, adaptive coded modulation is applied to each sub-channel of the selected user to improve the system performance further.

  3. MIMO Wiretap Channels with Arbitrarily Varying Eavesdropper Channel States

    CERN Document Server

    He, Xiang

    2010-01-01

    In this work, a class of information theoretic secrecy problems is addressed where the eavesdropper channel states are completely unknown to the legitimate parties. In particular, MIMO wiretap channel models are considered where the channel of the eavesdropper is arbitrarily varying over time. Assuming that the number of antennas of the eavesdropper is limited, the secrecy rate of the MIMO wiretap channel in the sense of strong secrecy is derived, and shown to match with the converse in secure degrees of freedom. It is proved that there exists a universal coding scheme that secures the confidential message against any sequence of channel states experienced by the eavesdropper. This yields the conclusion that secure communication is possible regardless of the location or channel states of (potentially infinite number of) eavesdroppers. Additionally, it is observed that, the present setting renders the secrecy capacity problems for multi-terminal wiretap-type channels more tractable as compared the case with fu...

  4. A Bayesian matching pursuit based scheduling algorithm for feedback reduction in MIMO broadcast channels

    KAUST Repository

    Shibli, Hussain J.

    2013-06-01

    Opportunistic schedulers rely on the feedback of all users in order to schedule a set of users with favorable channel conditions. While the downlink channels can be easily estimated at all user terminals via a single broadcast, several key challenges are faced during uplink transmission. First of all, the statistics of the noisy and fading feedback channels are unknown at the base station (BS) and channel training is usually required from all users. Secondly, the amount of network resources (air-time) required for feedback transmission grows linearly with the number of users. In this paper, we tackle the above challenges and propose a Bayesian based scheduling algorithm that 1) reduces the air-time required to identify the strong users, and 2) is agnostic to the statistics of the feedback channels and utilizes the a priori statistics of the additive noise to identify the strong users. Numerical results show that the proposed algorithm reduces the feedback air-time while improving detection in the presence of fading and noisy channels when compared to recent compressed sensing based algorithms. Furthermore, the proposed algorithm achieves a sum-rate throughput close to that obtained by noiseless dedicated feedback systems. © 2013 IEEE.

  5. Cooperative MIMO Relaying with Orthogonal Space-Time Block Codes in Wireless Channels with and without Keyholes

    Directory of Open Access Journals (Sweden)

    Tian Zhang

    2014-07-01

    Full Text Available Cooperative multiple-input multiple-output (MIMO relaying is investigated in the paper. We introduce DFAF selection MIMO relaying, where the relay equipped with multiple antennas can adaptively switch between decode-and-forward (DF and amplify-and-forward (AF according to its decoding state of the sourcemessage. We consider two wireless environment scenarios: 1The scenario with traditional channels are considered firstly. We analyze the outage performance of DF-AF selection MIMO relaying, and a closed-form expression is derived. In addition, the diversity order is obtained based on the expression. For comparison purpose, we also obtain the closed-form outage probability and the diversity order for the AF MIMO relaying and the DF MIMO relaying. 2We investigate the cooperative MIMO relaying in the presnece of keyholes secondly. We present performance analysis of orthogonal space-time block coded transmission for a cooperative MIMO relaying system with keyholes. For DF MIMO relaying, exact outage probability and symbol error probability (SEP are obtained. Regarding AF MIMO relaying and DF-AF selection MIMO relaying, the lower and upper bounds are derived. In both traditional and keyhole scenarios, theoretical analysis which has been further verified through Monte-Carlo simulations demonstrate that the DF-AF selection MIMO relaying has better performance than the AF MIMO relaying and the DF MIMO relaying.

  6. MIMO Identical Eigenmode Transmission System (IETS) - a Channel Decomposition Perspective

    OpenAIRE

    Shakir, Muhammad Zeeshan; Durrani, Tariq

    2007-01-01

    In the past few years considerable attention has been given to the design of Multiple-Input Multiple-Output (MIMO) Eigenmode Transmission Systems (EMTS). This paper presents an in-depth analysis of a new MIMO eigenmode transmission strategy. The non-linear decomposition technique called Geometric Mean Decomposition (GMD) is employed for the formation of eigenmodes over MIMO flatfading channel. Exploiting GMD technique, identical, parallel and independent transmission pipes are created for dat...

  7. Layered MAP algorithm for MIMO ISI channels

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The layered maximum a posteriori (L-MAP) algorithm has been proposed to detect signals under frequency selective fading multiple input multiple output (MIMO) channels. Compared to the optimum MAP detector, the L-MAP algorithm can efficiently identify signal bits, and the complexity grows linearly with the number of input antennas. The basic idea of L-MAP is to operate on each input sub-stream with an optimum MAP sequential detector separately by assuming the other streams are Gaussian noise. The soft output can also be forwarded to outer channel decoder for iterative decoding. Simulation results show that the proposed method can converge with a small number of iterations under different channel conditions and outperforms other sub-optimum detectors for rank-deficient channels.

  8. Efficient coordinated recovery of sparse channels in massive MIMO

    KAUST Repository

    Masood, Mudassir

    2015-01-01

    This paper addresses the problem of estimating sparse channels in massive MIMO-OFDM systems. Most wireless channels are sparse in nature with large delay spread. In addition, these channels as observed by multiple antennas in a neighborhood have approximately common support. The sparsity and common support properties are attractive when it comes to the efficient estimation of large number of channels in massive MIMO systems. Moreover, to avoid pilot contamination and to achieve better spectral efficiency, it is important to use a small number of pilots. We present a novel channel estimation approach which utilizes the sparsity and common support properties to estimate sparse channels and requires a small number of pilots. Two algorithms based on this approach have been developed that perform Bayesian estimates of sparse channels even when the prior is non-Gaussian or unknown. Neighboring antennas share among each other their beliefs about the locations of active channel taps to perform estimation. The coordinated approach improves channel estimates and also reduces the required number of pilots. Further improvement is achieved by the data-aided version of the algorithm. Extensive simulation results are provided to demonstrate the performance of the proposed algorithms.

  9. A Generalized Spatial Correlation Model for 3D MIMO Channels based on the Fourier Coefficients of Power Spectrums

    KAUST Repository

    Nadeem, Qurrat-Ul-Ain

    2015-05-07

    Previous studies have confirmed the adverse impact of fading correlation on the mutual information (MI) of two-dimensional (2D) multiple-input multiple-output (MIMO) systems. More recently, the trend is to enhance the system performance by exploiting the channel’s degrees of freedom in the elevation, which necessitates the derivation and characterization of three-dimensional (3D) channels in the presence of spatial correlation. In this paper, an exact closed-form expression for the Spatial Correlation Function (SCF) is derived for 3D MIMO channels. This novel SCF is developed for a uniform linear array of antennas with nonisotropic antenna patterns. The proposed method resorts to the spherical harmonic expansion (SHE) of plane waves and the trigonometric expansion of Legendre and associated Legendre polynomials. The resulting expression depends on the underlying arbitrary angular distributions and antenna patterns through the Fourier Series (FS) coefficients of power azimuth and elevation spectrums. The novelty of the proposed method lies in the SCF being valid for any 3D propagation environment. The developed SCF determines the covariance matrices at the transmitter and the receiver that form the Kronecker channel model. In order to quantify the effects of correlation on the system performance, the information-theoretic deterministic equivalents of the MI for the Kronecker model are utilized in both mono-user and multi-user cases. Numerical results validate the proposed analytical expressions and elucidate the dependence of the system performance on azimuth and elevation angular spreads and antenna patterns. Some useful insights into the behaviour of MI as a function of downtilt angles are provided. The derived model will help evaluate the performance of correlated 3D MIMO channels in the future.

  10. The Secrecy Capacity of the MIMO Wiretap Channel

    CERN Document Server

    Oggier, Frédérique

    2007-01-01

    We consider the MIMO wiretap channel, that is a MIMO broadcast channel where the transmitter sends some confidential information to one user which is a legitimate receiver, while the other user is an eavesdropper. Perfect secrecy is achieved when the the transmitter and the legitimate receiver can communicate at some positive rate, while insuring that the eavesdropper gets zero bits of information. In this paper, we compute the perfect secrecy capacity of the multiple antenna MIMO broadcast channel, where the number of antennas is arbitrary for both the transmitter and the two receivers.

  11. Decision-Directed Recursive Least Squares MIMO Channels Tracking

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available A new approach for joint data estimation and channel tracking for multiple-input multiple-output (MIMO channels is proposed based on the decision-directed recursive least squares (DD-RLS algorithm. RLS algorithm is commonly used for equalization and its application in channel estimation is a novel idea. In this paper, after defining the weighted least squares cost function it is minimized and eventually the RLS MIMO channel estimation algorithm is derived. The proposed algorithm combined with the decision-directed algorithm (DDA is then extended for the blind mode operation. From the computational complexity point of view being O3 versus the number of transmitter and receiver antennas, the proposed algorithm is very efficient. Through various simulations, the mean square error (MSE of the tracking of the proposed algorithm for different joint detection algorithms is compared with Kalman filtering approach which is one of the most well-known channel tracking algorithms. It is shown that the performance of the proposed algorithm is very close to Kalman estimator and that in the blind mode operation it presents a better performance with much lower complexity irrespective of the need to know the channel model.

  12. Robust Design of Pilot-symbol-aided MIMO Channel Estimation

    Institute of Scientific and Technical Information of China (English)

    LUO Zhen-dong; LIU Yuan-an; GAO Jin-chun

    2004-01-01

    This paper investigates pilot-symbol-aided channel estimation/prediction for Multiple-Input Multiple-Output (MIMO) systems in fast fading environments. We first derive the design criteria of the optimal pilot blocks for energy, power and bandwidth-limited systems, respectively. Then two low-complexity channel estimation schemes are provided. Finally, we present a robust Minimum Mean Square Error (MMSE) channel estimator based on channel time correlation. Simulation shows the proposed MMSE estimator is considerably insensitive to channel statistics and significantly outperforms the traditional estimators with a low additional complexity in fast fading environments. By simply adjusting some parameters, the MMSE estimator can work as an estimator and a predictor simultaneously.

  13. A Method of Time-Varying Rayleigh Channel Tracking in MIMO Radio System

    Institute of Scientific and Technical Information of China (English)

    GONG Yan-fei; HE Zi-shu; HAN Chun-lin

    2005-01-01

    A method of MIMO channel tracking based on Kalman filter and MMSE-DFE is proposed. The Kalman filter tracks the time-varying channel by using the MMSE-DFE decision and the MMSE-DFE conducts the next decision by using the channel estimates produced by the Kalman filter. Polynomial fitting is used to bridge the gap between the channel estimates produced by the Kalman filter and those needed for the DFE decision. Computer simulation demonstrates that this method can track the MIMO time-varying channel effectively.

  14. Opportunistic Interference Alignment in MIMO Interference Channels

    CERN Document Server

    Perlaza, Samir Medina; Lasaulce, Samson; Chaufray, Jean Marie

    2008-01-01

    We present two interference alignment techniques such that an opportunistic point-to-point multiple input multiple output (MIMO) link can reuse, without generating any additional interference, the same frequency band of a similar pre-existing primary link. In this scenario, we exploit the fact that under power constraints, although each radio maximizes independently its rate by water-filling on their channel transfer matrix singular values, frequently, not all of them are used. Therefore, by aligning the interference of the opportunistic radio it is possible to transmit at a significant rate while insuring zero-interference on the pre-existing link. We propose a linear pre-coder for a perfect interference alignment and a power allocation scheme which maximizes the individual data rate of the secondary link. Our numerical results show that significant data rates are achieved even for a reduced number of antennas.

  15. Secret Sharing over Fast-Fading MIMO Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Tan F. Wong

    2009-01-01

    Full Text Available Secret sharing over the fast-fading MIMO wiretap channel is considered. A source and a destination try to share secret information over a fast-fading MIMO channel in the presence of an eavesdropper who also makes channel observations that are different from but correlated to those made by the destination. An interactive, authenticated public channel with unlimited capacity is available to the source and destination for the secret sharing process. This situation is a special case of the “channel model with wiretapper” considered by Ahlswede and Csiszár. An extension of their result to continuous channel alphabets is employed to evaluate the key capacity of the fast-fading MIMO wiretap channel. The effects of spatial dimensionality provided by the use of multiple antennas at the source, destination, and eavesdropper are then investigated.

  16. Secret Sharing over Fast-Fading MIMO Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Bloch Matthieu

    2009-01-01

    Full Text Available Secret sharing over the fast-fading MIMO wiretap channel is considered. A source and a destination try to share secret information over a fast-fading MIMO channel in the presence of an eavesdropper who also makes channel observations that are different from but correlated to those made by the destination. An interactive, authenticated public channel with unlimited capacity is available to the source and destination for the secret sharing process. This situation is a special case of the "channel model with wiretapper" considered by Ahlswede and Csiszár. An extension of their result to continuous channel alphabets is employed to evaluate the key capacity of the fast-fading MIMO wiretap channel. The effects of spatial dimensionality provided by the use of multiple antennas at the source, destination, and eavesdropper are then investigated.

  17. Cooperative MIMO Transmissions in WSN Using Threshold Based MAC Protocol

    Directory of Open Access Journals (Sweden)

    J. Vidhya

    2010-08-01

    Full Text Available Sensor networks require robust and efficient communication protocols to maximise the network lifetime.Radio irregularity, channel fading and interference results in larger energy consumption and latency forpacket transmission over wireless channel. Cooperative multi-input multi-output (MIMO schemes whenincorporated in wireless senor network (WSN can significantly improve the communicationperformance. An inefficiently designed medium access control (MAC protocol however, may diminishthe performance gains of MIMO operation. Hence, this paper proposes a distributed threshold basedMAC protocol for cooperative MIMO transmissions using space time block codes (STBC. The protocoluses a thresholding scheme that is updated dynamically based on the queue length at the sending node toachieve lesser energy consumption and minimise latency ensuring the stability of transmission queues atthe nodes. STBC and code combining techniques are applied to utilise the inherent spatial diversity inwireless cooperative MIMO systems. Simulation results are provided to evaluate the performance of theproposed protocol and are compared with fixed group size cooperative MIMO MAC protocols with andwithout STBC coding. Results show that the proposed protocol outperforms point to point communicationas well as cooperative MIMO MAC protocols that use fixed group sizes. STBC technique for the proposedMAC protocol provides significant energy savings and minimises the packet delay by leveraging MIMOdiversity gains.

  18. Emulating Spatial Characteristics of MIMO Channels for OTA Testing

    DEFF Research Database (Denmark)

    Fan, Wei; Carreño, Xavier; Sun, Fan; Nielsen, Jesper Ødum; Knudsen, Mikael B.; Pedersen, Gert Frølund

    2013-01-01

    This paper discusses over the air (OTA) testing for multiple input multiple output (MIMO) capable terminals with emphasis on channel spatial characteristics emulation. A novel technique to obtain optimum power weights for the OTA probes based on convex optimization is proposed. The proposed...... technique emulates spatial correlation as well as introduces constraints on the maximum deviation between the target power azimuth spectrum (PAS) and the emulated PAS in terms of mean angle of arrival (AoA) and azimuth spread (AS). Simulation results show that the proposed emulation technique present better...

  19. 3D Massive MIMO Systems: Channel Modeling and Performance Analysis

    KAUST Repository

    Nadeem, Qurrat-Ul-Ain

    2015-03-01

    Multiple-input-multiple-output (MIMO) systems of current LTE releases are capable of adaptation in the azimuth only. More recently, the trend is to enhance the system performance by exploiting the channel\\'s degrees of freedom in the elevation through the dynamic adaptation of the vertical antenna beam pattern. This necessitates the derivation and characterization of three-dimensional (3D) channels. Over the years, channel models have evolved to address the challenges of wireless communication technologies. In parallel to theoretical studies on channel modeling, many standardized channel models like COST-based models, 3GPP SCM, WINNER, ITU have emerged that act as references for industries and telecommunication companies to assess system-level and link-level performances of advanced signal processing techniques over real-like channels. Given the existing channels are only two dimensional (2D) in nature; a large effort in channel modeling is needed to study the impact of the channel component in the elevation direction. The first part of this work sheds light on the current 3GPP activity around 3D channel modeling and beamforming, an aspect that to our knowledge has not been extensively covered by a research publication. The standardized MIMO channel model is presented, that incorporates both the propagation effects of the environment and the radio effects of the antennas. In order to facilitate future studies on the use of 3D beamforming, the main features of the proposed 3D channel model are discussed. A brief overview of the future 3GPP 3D channel model being outlined for the next generation of wireless networks is also provided. In the subsequent part of this work, we present an information-theoretic channel model for MIMO systems that supports the elevation dimension. The model is based on the principle of maximum entropy, which enables us to determine the distribution of the channel matrix consistent with the prior information on the angles of departure and

  20. Acoustic MIMO communications in a very shallow water channel

    Science.gov (United States)

    Zhou, Yuehai; Cao, Xiuling; Tong, Feng

    2015-12-01

    Underwater acoustic channels pose significant difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple input multiple output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.

  1. Acoustic MIMO Communications in a Very Shallow Water Channel

    Institute of Scientific and Technical Information of China (English)

    Yuehai Zhou; Xiuling Cao; Feng Tong

    2015-01-01

    Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple-input multiple-output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.

  2. A Versatile Propagation Channel Simulator for MIMO Link Level Simulation

    Directory of Open Access Journals (Sweden)

    Conrat Jean-Marc

    2007-01-01

    Full Text Available This paper presents a propagation channel simulator for polarized bidirectional wideband propagation channels. The generic channel model implemented in the simulator is a set of rays described by geometrical and propagation features such as the delay, 3D direction at the base station and mobile station and the polarization matrix. Thus, most of the wideband channel models including tapped delay line models, tap directional models, scatterer or geometrical models, ray-tracing or ray-launching results can be simulated. The simulator is composed of two major parts: firstly the channel complex impulse responses (CIR generation and secondly the channel filtering. CIRs (or CIR matrices for MIMO configurations are processed by specifying a propagation model, an antenna array configuration, a mobile direction, and a spatial sampling factor. For each sensor, independent arbitrary 3D vectorial antenna patterns can be defined. The channel filtering is based on the overlap-and-add method. The time-efficiency and parameterization of this method are discussed with realistic simulation setups. The global processing time for the CIR generation and the channel filtering is also evaluated for realistic configuration. A simulation example based on a bidirectional wideband channel model in urban environments illustrates the usefulness of the simulator.

  3. Measurement-Based Performance Evaluation of Advanced MIMO Transceiver Designs

    Directory of Open Access Journals (Sweden)

    Schneider Christian

    2005-01-01

    Full Text Available This paper describes the methodology and the results of performance investigations on a multiple-input multiple-output (MIMO transceiver scheme for frequency-selective radio channels. The method relies on offline simulations and employs real-time MIMO channel sounder measurement data to ensure a realistic channel modeling. Thus it can be classified in between the performance evaluation using some predefined channel models and the evaluation of a prototype hardware in field experiments. New aspects for the simulation setup are discussed, which are frequently ignored when using simpler model-based evaluations. Example simulations are provided for an iterative ("turbo" MIMO equalizer concept. The dependency of the achievable bit error rate performance on the propagation characteristics and on the variation in some system design parameters is shown, whereas the antenna constellation is of particular concern for MIMO systems. Although in many of the considered constellations turbo MIMO equalization appears feasible in real field scenarios, there exist cases with poor performance as well, indicating that in practical applications link adaptation of the transmitter and receiver processing to the environment is necessary.

  4. Spatial Correlation of PAN UWB-MIMO Channel Including User Dynamics

    DEFF Research Database (Denmark)

    Wang, Yu; Kovacs, Istvan Zsolt; Pedersen, Gert Frølund; Olesen, Kim

    . It is found the channel shows spatial correlated wideband power, and spatial uncorrelated complex channel coefficients at different frequencies and delays with respect to a correlation coefficient threshold of 0.7. The Kronecker model is proved not suitable for the investigated scenarios. The MIMO......In this paper we present and analyze spatial correlation properties of indoor 4x2 MIMO UWB channels in personal area network (PAN) scenarios. The presented results are based on measurement of radio links between an access point like device and a hand held or belt mounted device with dynamic user...

  5. An Error Probability Approach to MIMO Wiretap Channels

    CERN Document Server

    Belfiore, Jean-Claude

    2011-01-01

    We consider MIMO (Multiple Input Multiple Output) wiretap channels, where a legitimate transmitter Alice is communicating with a legitimate receiver Bob in the presence of an eavesdropper Eve, and communication is done via MIMO channels. We suppose that Alice's strategy is to use a codebook which has a lattice structure, which then allows her to perform coset encoding. We analyze Eve's probability of correctly decoding the message Alice meant to Bob, and from minimizing this probability, we derive a code design criterion for MIMO lattice wiretap codes. The case of block fading channels is treated similarly, and fast fading channels are derived as a particular case. The Alamouti code is carefully studied as an illustration of the analysis provided.

  6. Channel Estimation for MIMO MC-CDMA Systems

    CERN Document Server

    Sureshkumar, K; Vetrikanimozhi, A

    2011-01-01

    The concepts of MIMO MC-CDMA are not new but the new technologies to improve their functioning are an emerging area of research. In general, most mobile communication systems transmit bits of information in the radio space to the receiver. The radio channels in mobile radio systems are usually multipath fading channels, which cause inter-symbol interference (ISI) in the received signal. To remove ISI from the signal, there is a need of strong equalizer. In this thesis we have focused on simulating the MIMO MC-CDMA systems in MATLAB and designed the channel estimation for them.

  7. Feedback Reduction for Random Beamforming in Multiuser MIMO Broadcast Channel

    CERN Document Server

    Li, Jin-Hao; Tsai, Yu-Lun

    2011-01-01

    For the multiuser multiple-input multiple-output (MIMO) downlink channel, the users feedback their channel state information (CSI) to help the base station (BS) schedule users and improve the system sum rate. However, this incurs a large aggregate feedback bandwidth which grows linearly with the number of users. In this paper, we propose a novel scheme to reduce the feedback load in a downlink orthogonal space division multiple access (SDMA) system with zero-forcing receivers by allowing the users to dynamically determine the number of feedback bits to use according to multiple decision thresholds. Through theoretical analysis, we show that, while keeping the aggregate feedback load of the entire system constant regardless of the number of users, the proposed scheme almost achieves the optimal asymptotic sum rate scaling with respect to the number of users (also known as the multiuser diversity). Specifically, given the number of thresholds, the proposed scheme can achieve a constant portion of the optimal su...

  8. Receive Diversity and Ergodic Performance of Interference Alignment on the MIMO Gaussian Interference Channel

    CERN Document Server

    Guillaud, Maxime

    2010-01-01

    We consider interference alignment (IA) over K-user Gaussian MIMO interference channel (MIMO-IC) when the SNR is not asymptotically high. We introduce a generalization of IA which enables receive diversity inside the interference-free subspace. We generalize the existence criterion of an IA solution proposed by Yetis et al. to this case, thereby establishing a multi-user diversity-multiplexing trade-off (DMT) for the interference channel. Furthermore, we derive a closed-form tight lower-bound for the ergodic mutual information achievable using IA over a Gaussian MIMO-IC with Gaussian i.i.d. channel coefficients at arbitrary SNR, when the transmitted signals are white inside the subspace defined by IA. Finally, as an application of the previous results, we compare the performance achievable by IA at various operating points allowed by the DMT, to a recently introduced distributed method based on game theory.

  9. Color-Space-Based Visual-MIMO for V2X Communication

    OpenAIRE

    Jai-Eun Kim; Ji-Won Kim; Youngil Park; Ki-Doo Kim

    2016-01-01

    In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and w...

  10. Energy-Aware Adaptive Cooperative FEC Protocol in MIMO Channel for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yong Jin

    2013-01-01

    Full Text Available We propose an adaptive cooperative forward error correction (ACFEC based on energy efficiency combining Reed-Solomon (RS coder algorithm and multiple input multiple output (MIMO channel technology with monitoring signal-to-noise ratio (SNR in wireless sensor networks. First, we propose a new Markov chain model for FEC based on RS codes and derive the expressions for QoS on the basis of this model, which comprise four metrics: throughput, packet error rate, delay, and energy efficiency. Then, we apply RS codes with the MIMO channel technology to the cross-layer design. Numerical and simulation results show that the joint design of MIMO and adaptive cooperative FEC based on RS codes can achieve considerable spectral efficiency gain, real-time performance, reliability, and energy utility.

  11. Rewriting MIMO Channel Capacity for Antenna Configuration Comparison

    Directory of Open Access Journals (Sweden)

    Nicolae Crișan

    2015-06-01

    Full Text Available A rewriting of the MIMO channel capacity formula is proposed, in order to capture the direct influence of the array matrix (array configuration plus AoA information. The proposed theoretical framework will eventually allow direct comparison between antenna geometries in terms of channel capacity. Simulations indicate that, for small size arrays (up to 8x8, the configuration has a significant influence on the channel capacity, which is no longer the case for larger arrays.

  12. Capacity-Equivocation Region of the Gaussian MIMO Wiretap Channel

    CERN Document Server

    Ekrem, Ersen

    2010-01-01

    We study the Gaussian multiple-input multiple-output (MIMO) wiretap channel, which consists of a transmitter, a legitimate user, and an eavesdropper. In this channel, the transmitter sends a common message to both the legitimate user and the eavesdropper. In addition to this common message, the legitimate user receives a private message, which is desired to be kept hidden as much as possible from the eavesdropper. We obtain the entire capacity-equivocation region of the Gaussian MIMO wiretap channel. This region contains all achievable common message, private message, and private message's equivocation (secrecy) rates. In particular, we show the sufficiency of jointly Gaussian auxiliary random variables and channel input to evaluate the existing single-letter description of the capacity-equivocation region due to Csiszar-Korner.

  13. Blind Channel Estimation Enhancement for MIMO- OFDM Systems Under High Mobility Conditions

    Directory of Open Access Journals (Sweden)

    Aida Zaier

    2012-03-01

    Full Text Available In this paper, we propose an enhancement of a blind channel estimator based on a subspace approach in a MIMO OFDM context (Multi Input Multi Output Orthogonal Frequency Division Multiplexing in high mobility scenario. As known, the combination between the MIMO context and the OFDM system has stimulated mainly the evolution of the fourth generation broadband wireless communications. The simulations results have demonstrated the effectiveness of the approach for a 16 QAM modulation scheme and had been evaluated in term of bit error rate BER and mean square error MSE versus the signal to noise ratio SNR.

  14. Blind Channel Estimation Enhancement for Mimo- OFDM Systems under High Mobility Conditions

    CERN Document Server

    Zaier, Aida; 10.5121/ijwmn.2012.4115

    2012-01-01

    In this paper, we propose an enhancement of a blind channel estimator based on a subspace approach in a MIMO OFDM context (Multi Input Multi Output Orthogonal Frequency Division Multiplexing) in high mobility scenario. As known, the combination between the MIMO context and the OFDM system has stimulated mainly the evolution of the fourth generation broadband wireless communications. The simulations results have demonstrated the effectiveness of the approach for a 16 QAM modulation scheme and had been evaluated in term of bit error rate BER and mean square error MSE versus the signal to noise ratio SNR.

  15. Bidirectional Fano Algorithm for Lattice Coded MIMO Channels

    KAUST Repository

    Al-Quwaiee, Hessa

    2013-05-08

    Recently, lattices - a mathematical representation of infinite discrete points in the Euclidean space, have become an effective way to describe and analyze communication systems especially system those that can be modeled as linear Gaussian vector channel model. Channel codes based on lattices are preferred due to three facts: lattice codes have simple structure, the code can achieve the limits of the channel, and they can be decoded efficiently using lattice decoders which can be considered as the Closest Lattice Point Search (CLPS). Since the time lattice codes were introduced to Multiple Input Multiple Output (MIMO) channel, Sphere Decoder (SD) has been an efficient way to implement lattice decoders. Sphere decoder offers the optimal performance at the expense of high decoding complexity especially for low signal-to-noise ratios (SNR) and for high- dimensional systems. On the other hand, linear and non-linear receivers, Minimum Mean Square Error (MMSE), and MMSE Decision-Feedback Equalization (DFE), provide the lowest decoding complexity but unfortunately with poor performance. Several studies works have been conducted in the last years to address the problem of designing low complexity decoders for the MIMO channel that can achieve near optimal performance. It was found that sequential decoders using backward tree 
search can bridge the gap between SD and MMSE. The sequential decoder provides an interesting performance-complexity trade-off using a bias term. Yet, the sequential decoder still suffers from high complexity for mid-to-high SNR values. In this work, we propose a new algorithm for Bidirectional Fano sequential Decoder (BFD) in order to reduce the mid-to-high SNR complexity. Our algorithm consists of first constructing a unidirectional Sequential Decoder based on forward search using the QL decomposition. After that, BFD incorporates two searches, forward and backward, to work simultaneously till they merge and find the closest lattice point to the

  16. On the Feasibility of Linear Interference Alignment for MIMO Interference Broadcast Channels with Constant Coefficients

    OpenAIRE

    Liu, Tingting; Yang, Chenyang

    2012-01-01

    In this paper, we analyze the feasibility of linear interference alignment (IA) for multi-input-multi-output (MIMO) interference broadcast channel (MIMO-IBC) with constant coefficients. We pose and prove the necessary conditions of linear IA feasibility for general MIMO-IBC. Except for the proper condition, we find another necessary condition to ensure a kind of irreducible interference to be eliminated. We then prove the necessary and sufficient conditions for a special class of MIMO-IBC, wh...

  17. Energy-Efficient Channel Estimation in MIMO Systems

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The emergence of MIMO communications systems as practical high-data-rate wireless communications systems has created several technical challenges to be met. On the one hand, there is potential for enhancing system performance in terms of capacity and diversity. On the other hand, the presence of multiple transceivers at both ends has created additional cost in terms of hardware and energy consumption. For coherent detection as well as to do optimization such as water filling and beamforming, it is essential that the MIMO channel is known. However, due to the presence of multiple transceivers at both the transmitter and receiver, the channel estimation problem is more complicated and costly compared to a SISO system. Several solutions have been proposed to minimize the computational cost, and hence the energy spent in channel estimation of MIMO systems. We present a novel method of minimizing the overall energy consumption. Unlike existing methods, we consider the energy spent during the channel estimation phase which includes transmission of training symbols, storage of those symbols at the receiver, and also channel estimation at the receiver. We develop a model that is independent of the hardware or software used for channel estimation, and use a divide-and-conquer strategy to minimize the overall energy consumption.

  18. BER analysis of TDD downlink multiuser MIMO systems with imperfect channel state information

    Science.gov (United States)

    Zhou, Baolong; Jiang, Lingge; Zhao, Shengjie; He, Chen

    2011-12-01

    In downlink multiuser multiple-input multiple-output (MU-MIMO) systems, the zero-forcing (ZF) transmission is a simple and effective technique for separating users and data streams of each user at the transmitter side, but its performance depends greatly on the accuracy of the available channel state information (CSI) at the transmitter side. In time division duplex (TDD) systems, the base station estimates CSI based on uplink pilots and then uses it through channel reciprocity to generate the precoding matrix in the downlink transmission. Because of the constraints of the TDD frame structure and the uplink pilot overhead, there inevitably exists CSI delay and channel estimation error between CSI estimation and downlink transmission channel, which degrades system performance significantly. In this article, by characterizing CSI inaccuracies caused by CSI delay and channel estimation error, we develop a novel bit error rate (BER) expression for M-QAM signal in TDD downlink MU-MIMO systems. We find that channel estimation error causes array gain loss while CSI delay causes diversity gain loss. Moreover, CSI delay causes more performance degradation than channel estimation error at high signal-to-noise ratio for time varying channel. Our research is especially valuable for the design of the adaptive modulation and coding scheme as well as the optimization of MU-MIMO systems. Numerical simulations show accurate agreement with the proposed analytical expressions.

  19. Performance of RCPC-Encoded V-BLAST MIMO In Nakagami-m Fading Channel

    CERN Document Server

    Sari, L; Gunawan, D

    2010-01-01

    Multiple Input Multiple Output (MIMO) wireless communication link has been theoretically proven to be reliable and capable of achieving high capacity. However, these two advantageous characteristics tend to be addressed separately in many major researches. Researches on various approaches to attain both characteristics in a single MIMO system are still on-going and an established approach is yet to be concluded. To address this problem, in this paper a Vertical Bell Laboratories Layered Space-Time (V-BLAST) MIMO enhanced with Rate-Compatible Convolutional (RCPC) codes with Zero Forcing (ZF) and Minimum Mean Squared Error (MMSE)-based detection is proposed. The analytical BER of the system is presented and numerically analyzed. The system performance is analyzed in Nakagami-m fading channel, which provides accuracy and flexibility in matching the signals statistics compared to other fading models. The complexity which arises in the calculations of the RCPC codes parameters is significantly reduced by using equ...

  20. Linear Precoding for the MIMO Multiple Access Channel with Finite Alphabet Inputs and Statistical CSI

    OpenAIRE

    Wu, Yongpeng; Wen, Chao-Kai; Xiao, Chengshan; Gao, Xiqi; Schober, Robert

    2014-01-01

    In this paper, we investigate the design of linear precoders for the multiple-input multiple-output (MIMO) multiple access channel (MAC). We assume that statistical channel state information (CSI) is available at the transmitters and consider the problem under the practical finite alphabet input assumption. First, we derive an asymptotic (in the large system limit) expression for the weighted sum rate (WSR) of the MIMO MAC with finite alphabet inputs and Weichselberger's MIMO channel model. S...

  1. A rigorous proof of MIMO channel capacity's increase with antenna number

    Institute of Scientific and Technical Information of China (English)

    GONG Jian-min; M.R. Soleymani; J.F.Hayes

    2008-01-01

    It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity, in the multiple-input multiple-output(MIMO) communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.

  2. Precoder and decoder prediction in time-varying MIMO channel

    DEFF Research Database (Denmark)

    Nguyen, Tuan Hung; Leus, Geert; Khaled, Nadia

    2005-01-01

    system throughput. Thus, predicting the future channel conditions can improve not only the performance but also the throughput of many types of wireless systems. This is especially true for a wireless system where multiple antennas are applied at both link ends. In this report we propose and evaluate the...... performance of a prediction scheme for multiple input multiple output (MIMO) systems that apply spatial multiplexing. We aim at predicting the future precoder/decoder directly without going through the prediction of the channel matrix. The results show that in a slowly time varying channel an increase in the...

  3. Robust MSE precoder for imperfectly known MIMO wireless correlated channel

    Institute of Scientific and Technical Information of China (English)

    MA Peng-fei; ZHAO Hui; WANG Wen-bo

    2009-01-01

    Aimed at that only one form of channel statistic information is utilized in traditional robust precoder schemes: either the channel mean or the transmit antenna correlation in multiple-input multiple-output (MIMO) wireless system, this paper proposes robust precoder designs which exploit both of statistic information to minimize the equalization mean-square error (MSE) with power constraint. Two different power constraints are studied. Besides the usual sum power constraint over all antennas, the per-antenna power constraint is imposed at transmitter in this paper. Since each antenna has its own amplifier, individual power constraint on each antenna is more realistic. Especially in MIMO-OFDM systems, the Peak-to-Average Ratio (PAR) is one of main practical problems. Simulations show that the proposed schemes have better performance than traditional normalized zero forcing schemes for imperfectly known correlated channel. Moreover, per-antenna power constraint can efficiently decrease the demand of dynamic range of power amplifier on each transmit antenna, especially in MIMO-OFDM systems.

  4. Balancing Egoism and Altruism on MIMO Interference Channel

    CERN Document Server

    Ho, Zuleita Ka Ming

    2009-01-01

    This paper considers the so-called multiple-input-multiple-output interference channel (MIMO-IC) which has relevance in applications such as multi-cell coordination in cellular networks as well as spectrum sharing in cognitive radio networks among others. We address the design of precoding (i.e. beamforming) vectors at each sender with the aim of striking a compromise between beamforming gain at the intended receiver (Egoism) and the mitigation of interference created towards other receivers (Altruism). Combining egoistic and altruistic beamforming has been shown previously to be instrumental to optimizing the rates in a multiple-input-single-output interference channel MISO-IC (i.e. where receivers have no interference canceling capability) [5], [7]. Here we explore these game-theoretic concepts in the more general context of MIMO channels and using the framework of Bayesian games [17], allowing us to derive (semi-)distributed precoding techniques. We draw parallels with existing work on the MIMO-IC, includi...

  5. Impact of Feedback Channel on Measured MIMO Systems and Its Lower Bound

    Institute of Scientific and Technical Information of China (English)

    ZHANGDuo; WEIGuo; ZHUJinkang

    2005-01-01

    A lower bound of the rate in feedback channel from a receiver to a transmitter is presented for measured Multiple-input-multiple-output (MIMO) systems based on the formulae of the open-loop and the closedloop MIMO capacity, under the assumptions of quasi-static block-fading MIMO channel, independent nondispersive fading between each transmit and receive antenna, sampling with the period equal to the reciprocal of the signal bandwidth at the receiver, and zero feedback delay. Through Monte Carlo simulations~ we numerically validate the existence of the lower bound and show numerical results of the bound for system design. Also, we conclude that, the Signal-to-noise ratio (SNR) impacts little on the lower bound of the feedback rate for low antenna numbers, a closed-loop system with a feedback rate less than the lower bound is worse than a open-loop system, and the lower bound remains small with respect to the increase of antenna number for low SNRs. Finally, it is shown that the lower bound of the feedback rate and the conclusions are applicable to practical closed-loop MIMO systems.

  6. Hierarchical Decoupling Principle of a MIMO-CDMA Channel in Asymptotic Limits

    CERN Document Server

    Takeuchi, Keigo

    2007-01-01

    We analyze an uplink of a fast flat fading MIMO-CDMA channel in the case where the data symbol vector for each user follows an arbitrary distribution. The spectral efficiency of the channel with CSI at the receiver is evaluated analytically with the replica method. The main result is that the hierarchical decoupling principle holds in the MIMO-CDMA channel, i.e., the MIMO-CDMA channel is decoupled into a bank of single-user MIMO channels in the many-user limit, and each single-user MIMO channel is further decoupled into a bank of scalar Gaussian channels in the many-antenna limit for a fading model with a limited number of scatterers.

  7. Capacity of MIMO-OFDM with Pilot-Aided Channel Estimation

    Directory of Open Access Journals (Sweden)

    Cosovic Ivan

    2007-01-01

    Full Text Available An analytical framework is established to dimension the pilot grid for MIMO-OFDM operating in time-variant frequency selective channels. The optimum placement of pilot symbols in terms of overhead and power allocation is identified that maximizes the training-based capacity for MIMO-OFDM schemes without channel knowledge at the transmitter. For pilot-aided channel estimation (PACE with perfect interpolation, we show that the maximum capacity is achieved by placing pilots with maximum equidistant spacing given by the sampling theorem, if pilots are appropriately boosted. Allowing for realizable and possibly suboptimum estimators where interpolation is not perfect, we present a semianalytical method which finds the best pilot allocation strategy for the particular estimator.

  8. Interference Alignment Through User Cooperation for Two-cell MIMO Interfering Broadcast Channels

    CERN Document Server

    Shin, Wonjae; Lim, Jong-Bu; Shin, Changyong; Jang, Kyunghun

    2010-01-01

    This paper focuses on two-cell multiple-input multiple-output (MIMO) Gaussian interfering broadcast channels (MIMO-IFBC) with $K$ cooperating users on the cell-boundary of each BS. It corresponds to a downlink scenario for cellular networks with two base stations (BSs), and $K$ users equipped with Wi-Fi interfaces enabling to cooperate among users on a peer-to-peer basis. In this scenario, we propose a novel interference alignment (IA) technique exploiting user cooperation. Our proposed algorithm obtains the achievable degrees of freedom (DoF) of 2K when each BS and user have $M=K+1$ transmit antennas and $N=K$ receive antennas, respectively. Furthermore, the algorithm requires only a small amount of channel feedback information with the aid of the user cooperation channels. The simulations demonstrate that not only are the analytical results valid, but the achievable DoF of our proposed algorithm also outperforms those of conventional techniques.

  9. Cyclic Communication and the Inseparability of MIMO Multi-way Relay Channels

    KAUST Repository

    Chaaban, Anas

    2015-10-27

    The K-user MIMO multi-way relay channel (Ychannel) consisting of K users with M antennas each and a common relay node with N antennas is studied in this paper. Each user wants to exchange messages with all the other users via the relay. A transmission strategy is proposed for this channel. The proposed strategy is based on two steps: channel diagonalization and cyclic communication. The channel diagonalization is applied by using zero-forcing beam-forming. After channel diagonalization, the channel is decomposed into parallel sub-channels. Cyclic communication is then applied, where signal-space alignment for network-coding is used over each sub-channel. The proposed strategy achieves the optimal DoF region of the channel if N M. To prove this, a new degrees-of-freedom outer bound is derived. As a by-product, we conclude that the MIMO Y-channel is not separable, i.e., independent coding on separate sub-channels is not enough, and one has to code jointly over several sub-channels.

  10. Optimal Transmit Covariance for Ergodic MIMO Channels

    OpenAIRE

    Hanlen, Leif W.; Grant, Alex J.

    2005-01-01

    In this paper we consider the computation of channel capacity for ergodic multiple-input multiple-output channels with additive white Gaussian noise. Two scenarios are considered. Firstly, a time-varying channel is considered in which both the transmitter and the receiver have knowledge of the channel realization. The optimal transmission strategy is water-filling over space and time. It is shown that this may be achieved in a causal, indeed instantaneous fashion. In the second scenario, only...

  11. Bayes-Optimal Joint Channel-and-Data Estimation for Massive MIMO With Low-Precision ADCs

    Science.gov (United States)

    Wen, Chao-Kai; Wang, Chang-Jen; Jin, Shi; Wong, Kai-Kit; Ting, Pangan

    2016-05-01

    This paper considers a multiple-input multiple-output (MIMO) receiver with very low-precision analog-to-digital convertors (ADCs) with the goal of developing massive MIMO antenna systems that require minimal cost and power. Previous studies demonstrated that the training duration should be {\\em relatively long} to obtain acceptable channel state information. To address this requirement, we adopt a joint channel-and-data (JCD) estimation method based on Bayes-optimal inference. This method yields minimal mean square errors with respect to the channels and payload data. We develop a Bayes-optimal JCD estimator using a recent technique based on approximate message passing. We then present an analytical framework to study the theoretical performance of the estimator in the large-system limit. Simulation results confirm our analytical results, which allow the efficient evaluation of the performance of quantized massive MIMO systems and provide insights into effective system design.

  12. ERGODIC CAPACITY FORMULA OF MIMO-OFDM SYSTEMS UNDER CORRELATED FREQUENCY SELECTIVE RAYLEIGH FADING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An explicit formula for the ergodic capacity of Orthogonal Frequency Division Multiplexing (OFDM)-based Multiple-Input Multiple-Output (MIMO) systems under correlated frequency selective Rayleigh channels is derived, by simplifying the channel response matrix in frequency domain into the so-called Kronecker model composed of three kinds of correlations, i.e. multipath tap gain correlation and spatial fading correlations at both transmitter and receiver. The derived formula is very simple and convenient for one to estimate the effects of all three kinds of correlations on MIMO-OFDM capacity. If taps are independent, there is a very simple expression for the ergodic capacity. In case of tap correlation, the capacity formula could be further given in an integral expression. The validity of the new formula is verified and the effects of correlations, delay spread as well as the number of subcarriers on the ergodic capacity are evaluated via Monte Carlo simulations.

  13. Filter Design With Secrecy Constraints: The MIMO Gaussian Wiretap Channel

    Science.gov (United States)

    Reboredo, Hugo; Xavier, Joao; Rodrigues, Miguel R. D.

    2013-08-01

    This paper considers the problem of filter design with secrecy constraints, where two legitimate parties (Alice and Bob) communicate in the presence of an eavesdropper (Eve), over a Gaussian multiple-input-multiple-output (MIMO) wiretap channel. This problem involves designing, subject to a power constraint, the transmit and the receive filters which minimize the mean-squared error (MSE) between the legitimate parties whilst assuring that the eavesdropper MSE remains above a certain threshold. We consider a general MIMO Gaussian wiretap scenario, where the legitimate receiver uses a linear Zero-Forcing (ZF) filter and the eavesdropper receiver uses either a ZF or an optimal linear Wiener filter. We provide a characterization of the optimal filter designs by demonstrating the convexity of the optimization problems. We also provide generalizations of the filter designs from the scenario where the channel state is known to all the parties to the scenario where there is uncertainty in the channel state. A set of numerical results illustrates the performance of the novel filter designs, including the robustness to channel modeling errors. In particular, we assess the efficacy of the designs in guaranteeing not only a certain MSE level at the eavesdropper, but also in limiting the error probability at the eavesdropper. We also assess the impact of the filter designs on the achievable secrecy rates. The penalty induced by the fact that the eavesdropper may use the optimal non-linear receive filter rather than the optimal linear one is also explored in the paper.

  14. 阵列布局对机载 MIMO 信道容量影响%The Effect of Array Structures on Airborne MIMO Channel Capacity

    Institute of Scientific and Technical Information of China (English)

    陈自力; 高喜俊

    2015-01-01

    为进一步提高空地(air-to-ground,ATG)下行通信容量,建立了三维基于散射体分布的空地 MIMO 单跳同心椭圆环信道模型,结合机载多入多出(multiple input multiple output,MIMO)均匀线阵以及圆阵布局方案,推导了基于阵列结构分量的机载 MIMO 信道相关矩阵,为通过合理设计机载 MIMO 天线结构来提升 ATG 传输速率,分析了阵列结构参数对遍历容量的影响。仿真表明,受 ATG 远距离通信影响,需要扩大天线间隔来提高 MIMO信道容量,且相比于线阵布局,圆阵布局更加适应飞行姿态变化,获得较高的信道容量。%To improve the communication capacity of air-to-ground (ATG)downlinks,the three-dimensional geometrically based single bounce concentric elliptic ring scattering (GBSBCERS)channel model of ATG multiple input multiple output (MIMO)was set up.Combing with the linear array layout and circular array layout of airborne MIMO,the analytic formula of airborne MIMO channel correlation matrix and ergodic capacity was deduced based on array structures.Then the influ-ence of array structures on the ergodic capacity was analyzed to improve the ATG transmission rate by means of antennas layout.The simulation results shown that the MIMO channel capacity will increase along with the increase of antenna dis-tance in the influence of ATG remote communication,and the circular antenna layout which has more channel capacity than linear antenna layout can adapt to the UAV attitude change.

  15. Diversity of MIMO Multihop Relay Channels

    CERN Document Server

    Yang, Sheng

    2007-01-01

    We consider slow fading relay channels with a single multi-antenna source-destination terminal pair. The source signal arrives at the destination via N hops through N-1 layers of relays. We analyze the diversity of such channels with fixed network size at high SNR. In the clustered case where the relays within the same layer can have full cooperation, the cooperative decode-and-forward (DF) scheme is shown to be optimal in terms of the diversity-multiplexing tradeoff (DMT). The upper bound on the DMT, the cut-set bound, is attained. In the non-clustered case, we show that the naive amplify-and-forward (AF) scheme has the maximum multiplexing gain of the channel but is suboptimal in diversity, as compared to the cut-set bound. To improve the diversity, space-time relay processing is introduced through the parallel partition of the multihop channel. The idea is to let the source signal go through K different "AF paths" in the multihop channel. This parallel AF scheme creates a parallel channel in the time domai...

  16. A Robust Pre-Filter and Power Loading Design for Time Reversal UWB Systems over Time-Correlated MIMO Channels

    Directory of Open Access Journals (Sweden)

    Sajjad Alizadeh

    2014-04-01

    Full Text Available Conventional Time Reversal (TR technique suffers from performance degradation in time varying Multiple-Input Multiple-Output Ultra-Wideband (MIMO-UWB systems due to outdating Channel State Information (CSI over time progressions. That is, the outdated CSI degrades the TR performance significantly in time varying channels. The correlation property of time correlated channels can improve the TR performance against other traditional TR designs. Based on this property, at first, we propose a robust TR-MIMO-UWB system design for a time-varying channel in which the CSI is updated only at the beginning of each block of data where the CSI is assumed to be known. As the channel varies over time, pre-processor blindly pre-equalizes the channel during the next symbol time by using the correlation property. Then, a novel recursive power allocation strategy is derived over time-correlated time-varying TR-MIMO-UWB channels. We show that the proposed power loading technique, considerably improves the BER performance of TR-MIMO-UWB system in imperfect CSI with robust pre-filter. The proposed algorithms lead to a cost-efficient CSI updating procedure for the TR optimization. Simulation results are provided to confirm the new design performance against traditional method.

  17. Impact of MIMO Co-Channel Interference

    DEFF Research Database (Denmark)

    Rahman, Muhammad Imadur; De Carvalho, Elisabeth; Prasad, Ramjee

    2007-01-01

    In a real cellular system, existence of a number of multi-antenna schemes in neighboring cells means that different multi-antenna schemes will experience Co-Channel Interference (CCI) from the same or other multi-antenna schemes. In this work, we have summarized our analysis and simulations relat...

  18. Cooperative Algorithms for MIMO Interference Channels

    CERN Document Server

    Peters, Steven W

    2010-01-01

    Interference alignment is a transmission technique for exploiting all available degrees of freedom in the interference channel with an arbitrary number of users. Most prior work on interference alignment, however, neglects interference from other nodes in the network not participating in the alignment operation. This paper proposes three generalizations of interference alignment for the multiple-antenna interference channel with multiple users that account for colored noise, which models uncoordinated interference. First, a minimum interference-plus-noise leakage algorithm is presented, and shown to be equivalent to previous subspace methods when noise is spatially white or negligible. A joint minimum mean squared error design is then proposed that jointly optimizes the transmit precoders and receive spatial filters, whereas previous designs neglect the receive spatial filter. This algorithm is shown to be a generalization of previous joint MMSE designs for other system configurations such as the broadcast ch...

  19. Color-Space-Based Visual-MIMO for V2X Communication †

    Science.gov (United States)

    Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo

    2016-01-01

    In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance. PMID:27120603

  20. AN ITERATIVE PARTICLE FILTER SIGNAL DETECTOR FOR MIMO FAST FADING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    Yang Tao; Hu Bo

    2008-01-01

    For flat fast fading Multiple-Input Multiple-Output (MIMO) channels, this paper presents a sampling based channel estimation and an iterative Particle Filter (PF) signal detection scheme. The channel estimation is comprised of two parts: the adaptive iterative update on the channel distribution mean and a regular update on the "adaptability" via pilot. In the detection procedure, the PF is employed to produce the optimal decision given the known received signal and the sequence of the channel samples, where an asymptotic optimal importance density is constructed, and in terms of the asymptotic update order, the Parallel Importance Update (PIU) and the Serial Importance Update (SIU) scheme are performed respectively. The simulation results show that for the given fading channel, if an appropriate pilot mode is selected, the proposed scheme is more robust than the conventional Kalman filter based superimposed detection scheme.

  1. A novel power and offset allocation method for spatial multiplexing MIMO Systems in optical wireless channels

    KAUST Repository

    Park, Kihong

    2011-12-01

    We consider optical wireless communication which can be utilized for illumination and communication by relying on lighting devices. Due to the limited bandwidth of optical sources, it is challenging to achieve high data rate in optical wireless systems. In order to obtain a multiplexing gain and high spectral efficiency, we design an optical multi-input multi-output (MIMO) system utilizing a singular value decomposition-based spatial multiplexing and adaptive modulation. We note that the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels. In this paper, we generalize the result of power allocation method in [1] for arbitrary number of transmit and receive antennas in optical wireless MIMO systems. Based on three constraints, namely, the nonnegativity, the aggregate optical power, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size for maximum sum rate. From some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency than the method that allocates the optical power equally for each data stream. © 2011 IEEE.

  2. Optimum Design for Coexistence Between Matrix Completion Based MIMO Radars and a MIMO Communication System

    OpenAIRE

    Li, Bo; Petropulu, Athina P.; Trappe, Wade

    2015-01-01

    Recently proposed multiple input multiple output radars based on matrix completion (MIMO-MC) employ sparse sampling to reduce the amount of data that need to be forwarded to the radar fusion center, and as such enable savings in communication power and bandwidth. This paper proposes designs that optimize the sharing of spectrum between a MIMO-MC radar and a communication system, so that the latter interferes minimally with the former. First, the communication system transmit covariance matrix...

  3. Full Rank Solutions for the MIMO Gaussian Wiretap Channel With an Average Power Constraint

    Science.gov (United States)

    Fakoorian, S. Ali. A.; Swindlehurst, A. Lee

    2013-05-01

    This paper considers a multiple-input multiple-output (MIMO) Gaussian wiretap channel model, where there exists a transmitter, a legitimate receiver and an eavesdropper, each equipped with multiple antennas. In this paper, we first revisit the rank property of the optimal input covariance matrix that achieves the secrecy capacity of the multiple antenna MIMO Gaussian wiretap channel under the average power constraint. Next, we obtain necessary and sufficient conditions on the MIMO wiretap channel parameters such that the optimal input covariance matrix is full-rank, and we fully characterize the resulting covariance matrix as well. Numerical results are presented to illustrate the proposed theoretical findings.

  4. MIMO channel capacity with full CSI at Low SNR

    KAUST Repository

    Tall, Abdoulaye

    2012-10-01

    In this paper, we characterize the ergodic capacity of Multiple Input Multiple Output (MIMO) Rayleigh fading channels with full channel state information (CSI) at both the transmitter (CSI-T) and the receiver (CSI-R) at asymptotically low signal-to-noise ratio (SNR). A simple analytical expression of the capacity is derived for any number of transmit and receive antennas. This characterization clearly shows the substantial gain in terms of capacity over the no CSI-T case and gives a good insight on the effect of the number of antennas used. In addition, an On-Off transmission scheme is proposed and is shown to be asymptotically capacity-achieving. © 2012 IEEE.

  5. Comparison between MC-CDMA and CDMA-OFDM/OQAM systems in presence of MIMO channel

    Directory of Open Access Journals (Sweden)

    Radhia Gharsallah

    2012-07-01

    Full Text Available In this paper, we present a comparison between MC-CDMA and CDMA-OFDM/OQAM systems in the case of MIMO channel. The advanced Multi Carrier CDMA OFDM/OQAM modulation is a combination of CDMA and OFDM/OQAM. This combination takes advantages from multicarrier modulation and spread spectrum. Indeed, the use of OFDM has proved its ability to fight against frequency selective channels but the insertion of guard interval yields spectral efficiency loss and sensitivity to frequency dispersion due to the use of rectangular pulse shape. Thus, cyclic prefix OFDM is replaced by an advanced #64257;lterbank-based multicarrier system OFDM/OQAM that operates without guard interval. However, OFDM/OQAM provides orthogonality only on the real domain, so transmitted symbols must be real valued. In the other hand, the CDMA component has two advantages: multiple access interference cancellation and providing orthogonality in the complex domain. From the orthogonality property provided, the Alamouti ST code can be combined with MC-CDMA-OQAM system in order to exploit space and time diversity. Numerical results show the utility of this new wireless communication system MIMO-CDMA-OFDM/OQAM in comparison with MIMO-MC-CDMA system

  6. Spectral Subtraction Approach for Interference Reduction of MIMO Channel Wireless Systems

    Directory of Open Access Journals (Sweden)

    Tomohiro Ono

    2005-08-01

    Full Text Available In this paper, a generalized spectral subtraction approach for reducing additive impulsive noise, narrowband signals, white Gaussian noise and DS-CDMA interferences in MIMO channel DS-CDMA wireless communication systems is investigated. The interference noise reduction or suppression is essential problem in wireless mobile communication systems to improve the quality of communication. The spectrum subtraction scheme is applied to the interference noise reduction problems for noisy MIMO channel systems. The interferences in space and time domain signals can effectively be suppressed by selecting threshold values, and the computational load with the FFT is not large. Further, the fading effects of channel are compensated by spectral modification with the spectral subtraction process. In the simulations, the effectiveness of the proposed methods for the MIMO channel DS-CDMA is shown to compare with the conventional MIMO channel DS-CDMA.

  7. On the low SNR capacity of MIMO fading channels with imperfect channel state information

    KAUST Repository

    Benkhelifa, Fatma

    2014-05-01

    The capacity of Multiple Input Multiple Output (MIMO) Rayleigh fading channels with full knowledge of channel state information (CSI) at both the transmitter and the receiver (CSI-TR) has been shown recently to scale at low Signal-to-Noise Ratio (SNR) essentially as SNR log(1=SNR), independently of the number of transmit and receive antennas. In this paper, we investigate the ergodic capacity of MIMO Rayleigh fading channel with estimated channel state information at the transmitter (CSI-T) and possibly imperfect channel state information at the receiver (CSI-R). Our framework can be seen as a generalization of previous works as it can capture the perfect CSI-TR as a special case when the estimation error variance goes to zero. In our work, we mainly focus on the low SNR regime and we show that the capacity scales as (1-α) SNR log(1=SNR), where α is the estimation error variance. This characterization shows the loss of performance due to error estimation over the perfect channel state information at both the transmitter and the receiver. As a by-product of our new analysis, we show that our framework can also be extended to characterize the capacity of MIMO Rician fading channels at low SNR with possibly imperfect CSI-T and CSI-R. © 2014 IFIP.

  8. On the low SNR capacity of MIMO fading channels with imperfect channel state information

    KAUST Repository

    Benkhelifa, Fatma

    2014-06-01

    The capacity of multiple-input multiple-output (MIMO) Rayleigh fading channels with full knowledge of channel state information (CSI) at both the transmitter and the receiver (CSI-TR) has been shown recently to scale at low signal-to-noise ratio (SNR) essentially as SNR log(1/SNR), independently of the number of transmit and receive antennas. In this paper, we investigate the ergodic capacity of MIMO Rayleigh fading channel with estimated channel state information at the transmitter (CSI-T) and possibly imperfect channel state information at the receiver (CSI-R). Our framework can be seen as a generalization of previous works as it can capture the perfect CSI-TR as a special case when the estimation error variance goes to zero. In this paper, we mainly focus on the low SNR regime, and we show that the capacity scales as (1-α) SNR log(1/SNR), where α is the estimation error variance. This characterization shows the loss of performance due to error estimation over the perfect channel state information at both the transmitter and the receiver. As a by-product of our new analysis, we show that our framework can be also extended to characterize the capacity of MIMO Rician fading channels at low SNR with possibly imperfect CSI-T and CSI-R. © 1972-2012 IEEE.

  9. Massive MIMO Systems with Hardware-Constrained Base Stations

    OpenAIRE

    Bjornson, Emil; Matthaiou, Michail; Debbah, Merouane

    2014-01-01

    Massive multiple-input multiple-output (MIMO) systems are cellu-lar networks where the base stations (BSs) are equipped with un-conventionally many antennas. Such large antenna arrays offer huge spatial degrees-of-freedom for transmission optimization; in partic-ular, great signal gains, resilience to imperfect channel knowledge, and small inter-user interference are all achievable without exten-sive inter-cell coordination. The key to cost-efficient deployment of large arrays is the use of h...

  10. Outage analysis of interference-limited systems using STBC with co-channel MIMO interferers

    Institute of Scientific and Technical Information of China (English)

    Yongzhao LI; Leonard J.CIMINI,JR.; Nageen HIMAYAT

    2009-01-01

    The performance of Space-Time Block Coding (STBC) with co-channel MIMO interference is investigated.For an interference-limited environment, the closed-form ex-pressions for the probability density functions of the signal-to-interference ratio are derived and applied to analyze the outage probability with three typical types of co-channel MIMO interferers: STBC, open-loop spatial multiplexing and closed-loop spatial multiplexing. Both theoretical anal-yses and simulation results show that the performance of STBC is independent of the MIMO modes used in the in-terfering links.

  11. MIMO Relaying Broadcast Channels with Linear Precoding and Quantized Channel State Information Feedback

    CERN Document Server

    Xu, Wei; Lu, Wu-Sheng; 10.1109/TSP.2010.2056687

    2012-01-01

    Multi-antenna relaying has emerged as a promising technology to enhance the system performance in cellular networks. However, when precoding techniques are utilized to obtain multi-antenna gains, the system generally requires channel state information (CSI) at the transmitters. We consider a linear precoding scheme in a MIMO relaying broadcast channel with quantized CSI feedback from both two-hop links. With this scheme, each remote user feeds back its quantized CSI to the relay, and the relay sends back the quantized precoding information to the base station (BS). An upper bound on the rate loss due to quantized channel knowledge is first characterized. Then, in order to maintain the rate loss within a predetermined gap for growing SNRs, a strategy of scaling quantization quality of both two-hop links is proposed. It is revealed that the numbers of feedback bits of both links should scale linearly with the transmit power at the relay, while only the bit number of feedback from the relay to the BS needs to gr...

  12. MIMO transmit scheme based on morphological perceptron with competitive learning.

    Science.gov (United States)

    Valente, Raul Ambrozio; Abrão, Taufik

    2016-08-01

    This paper proposes a new multi-input multi-output (MIMO) transmit scheme aided by artificial neural network (ANN). The morphological perceptron with competitive learning (MP/CL) concept is deployed as a decision rule in the MIMO detection stage. The proposed MIMO transmission scheme is able to achieve double spectral efficiency; hence, in each time-slot the receiver decodes two symbols at a time instead one as Alamouti scheme. Other advantage of the proposed transmit scheme with MP/CL-aided detector is its polynomial complexity according to modulation order, while it becomes linear when the data stream length is greater than modulation order. The performance of the proposed scheme is compared to the traditional MIMO schemes, namely Alamouti scheme and maximum-likelihood MIMO (ML-MIMO) detector. Also, the proposed scheme is evaluated in a scenario with variable channel information along the frame. Numerical results have shown that the diversity gain under space-time coding Alamouti scheme is partially lost, which slightly reduces the bit-error rate (BER) performance of the proposed MP/CL-NN MIMO scheme. PMID:27135805

  13. Impact of Clustering in Indoor MIMO Propagation Using a Hybrid Channel Model

    Directory of Open Access Journals (Sweden)

    Tang Zhongwei

    2005-01-01

    Full Text Available The clustering of propagating signals in indoor environments can influence the performance of multiple-input multiple-output (MIMO systems that employ multiple-element antennas at the transmitter and receiver. In order to clarify the effect of clustering propagation on the performance of indoor MIMO systems, we propose a simple and efficient indoor MIMO channel model. The proposed model, which is validated with on-site measurements, combines the statistical characteristics of signal clusters with deterministic ray tracing approach. Using the proposed model, the effect of signal clusters and the presence of the line-of-sight component in indoor Ricean channels are studied. Simulation results on channel efficiency and the angular sensitivity for different antenna array topologies inside a specified indoor scenario are also provided. Our investigations confirm that the clustering of signals significantly affects the spatial correlation, and hence, the achievable indoor MIMO capacity.

  14. Cooperative MIMO Transmissions in WSN Using Threshold Based MAC Protocol

    OpenAIRE

    Vidhya, J.; Dananjayan, P.

    2010-01-01

    Sensor networks require robust and efficient communication protocols to maximise the network lifetime.Radio irregularity, channel fading and interference results in larger energy consumption and latency forpacket transmission over wireless channel. Cooperative multi-input multi-output (MIMO) schemes whenincorporated in wireless senor network (WSN) can significantly improve the communicationperformance. An inefficiently designed medium access control (MAC) protocol however, may diminishthe per...

  15. Mode Switching for the Multi-Antenna Broadcast Channel Based on Delay and Channel Quantization

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2009-01-01

    Full Text Available Imperfect channel state information degrades the performance of multiple-input multiple-output (MIMO communications; its effects on single-user (SU and multiuser (MU MIMO transmissions are quite different. In particular, MU-MIMO suffers from residual interuser interference due to imperfect channel state information while SU-MIMO only suffers from a power loss. This paper compares the throughput loss of both SU and MU-MIMO in the broadcast channel due to delay and channel quantization. Accurate closed-form approximations are derived for achievable rates for both SU and MU-MIMO. It is shown that SU-MIMO is relatively robust to delayed and quantized channel information, while MU-MIMO with zero-forcing precoding loses its spatial multiplexing gain with a fixed delay or fixed codebook size. Based on derived achievable rates, a mode switching algorithm is proposed, which switches between SU and MU-MIMO modes to improve the spectral efficiency based on average signal-to-noise ratio (SNR, normalized Doppler frequency, and the channel quantization codebook size. The operating regions for SU and MU modes with different delays and codebook sizes are determined, and they can be used to select the preferred mode. It is shown that the MU mode is active only when the normalized Doppler frequency is very small, and the codebook size is large.

  16. Spreading Code Assignment Strategies for MIMO-CDMA Systems Operating in Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Claude D'Amours

    2009-01-01

    Full Text Available Code Division Multiple Access (CDMA and multiple input multiple output- (MIMO- CDMA systems suffer from multiple access interference (MAI which limits the spectral efficiency of these systems. By making these systems more power efficient, we can increase the overall spectral efficiency. This can be achieved through the use of improved modulation and coding techniques. Conventional MIMO-CDMA systems use fixed spreading code assignments. By strategically selecting the spreading codes as a function of the data to be transmitted, we can achieve coding gain and introduce additional degrees of freedom in the decision variables at the output of the matched filters. In this paper, we examine the bit error rate performance of parity bit-selected spreading and permutation spreading under different wireless channel conditions. A suboptimal detection technique based on maximum likelihood detection is proposed for these systems operating in frequency selective channels. Simulation results demonstrate that these code assignment techniques provide an improvement in performance in terms of bit error rate (BER while providing increased spectral efficiency compared to the conventional system. Moreover, the proposed strategies are more robust to channel estimation errors as well as spatial correlation.

  17. Spreading Code Assignment Strategies for MIMO-CDMA Systems Operating in Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Dahmane AdelOmar

    2009-01-01

    Full Text Available Abstract Code Division Multiple Access (CDMA and multiple input multiple output- (MIMO- CDMA systems suffer from multiple access interference (MAI which limits the spectral efficiency of these systems. By making these systems more power efficient, we can increase the overall spectral efficiency. This can be achieved through the use of improved modulation and coding techniques. Conventional MIMO-CDMA systems use fixed spreading code assignments. By strategically selecting the spreading codes as a function of the data to be transmitted, we can achieve coding gain and introduce additional degrees of freedom in the decision variables at the output of the matched filters. In this paper, we examine the bit error rate performance of parity bit-selected spreading and permutation spreading under different wireless channel conditions. A suboptimal detection technique based on maximum likelihood detection is proposed for these systems operating in frequency selective channels. Simulation results demonstrate that these code assignment techniques provide an improvement in performance in terms of bit error rate (BER while providing increased spectral efficiency compared to the conventional system. Moreover, the proposed strategies are more robust to channel estimation errors as well as spatial correlation.

  18. Approximating the constellation constrained capacity of the MIMO channel with discrete input

    DEFF Research Database (Denmark)

    Yankov, Metodi Plamenov; Forchhammer, Søren; Larsen, Knud J.;

    2015-01-01

    In this paper the capacity of a Multiple Input Multiple Output (MIMO) channel is considered, subject to average power constraint, for multi-dimensional discrete input, in the case when no channel state information is available at the transmitter. We prove that when the constellation size grows, t...... for the equivalent orthogonal channel, obtained by the singular value decomposition. Furthermore, lower bounds on the constrained capacity are derived for the cases of square and tall MIMO matrix, by optimizing the constellation for the equivalent channel, obtained by QR decomposition....

  19. Approximating the Constellation Constrained Capacity of the MIMO Channel with Discrete Input

    DEFF Research Database (Denmark)

    Yankov, Metodi Plamenov; Forchhammer, Søren; Larsen, Knud J.;

    2015-01-01

    In this paper the capacity of a Multiple Input Multiple Output (MIMO) channel is considered, subject to average power constraint, for multi-dimensional discrete input, in the case when no channel state information is available at the transmitter. We prove that when the constellation size grows, t...... for the equivalent orthogonal channel, obtained by the singular value decomposition. Furthermore, lower bounds on the constrained capacity are derived for the cases of square and tall MIMO matrix, by optimizing the constellation for the equivalent channel, obtained by QR decomposition....

  20. Estimation of MIMO channel capacity from phase-noise impaired measurements

    DEFF Research Database (Denmark)

    Pedersen, Troels; Yin, Xuefeng; Fleury, Bernard Henri

    2008-01-01

    Due to the significantly reduced cost and effort for system calibration time-division multiplexing (TDM) is a commonly used technique to switch between the transmit and receive antennas in multiple-input multiple-output (MIMO) radio channel sounding. Nonetheless, Baum et al. [1], [2] have shown...... that phase noise of the transmitter and receiver local oscillators, when it is assumed to be a white Gaussian random process, can cause large errors of the estimated channel capacity of a low-rank MIMO channel when the standard channel matrix estimator is used. Experimental evidence shows that...

  1. Optimal transmission strategy for spatially correlated MIMO systems with channel statistical information

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhen-shan; XU Guo-zhi

    2007-01-01

    In real multiple-input multiple-output (MIMO) systems, the perfect channel state information (CSI) may be costly or impossible to acquire. But the channel statistical information can be considered relatively stationary during long-term transmission.The statistical information can be obtained at the receiver and fed back to the transmitter and do not require frequent update. By exploiting channel mean and covariance information at the transmitter simultaneously, this paper investigates the optimal transmission strategy for spatially correlated MIMO channels. An upper bound of ergodic capacity is derived and taken as the performance criterion. Simulation results are also given to show the performance improvement of the optimal transmission strategy.

  2. Feedback-Topology Designs for Interference Alignment in MIMO Interference Channels

    CERN Document Server

    Cho, Sungyoon; Huang, Kaibin; Kim, Dongku; Lau, Vincent K N; Seo, Hanbyul; Kim, Byounghoon

    2011-01-01

    Interference alignment (IA) is a joint-transmission technique that achieves the capacity of the interference channel for high signal-to-noise ratios (SNRs). Most prior work on IA is based on the impractical assumption that perfect and global channel-state information(CSI) is available at all transmitters. To implement IA, each receiver has to feed back CSI to all interferers, resulting in overwhelming feedback overhead. In particular, the sum feedback rate of each receiver scales quadratically with the number of users even if the quantized CSI is fed back. To substantially suppress feedback overhead, this paper focuses on designing efficient arrangements of feedback links, called feedback topologies, under the IA constraint. For the multiple-input-multiple-output (MIMO) K-user interference channel, we propose the feedback topology that supports sequential CSI exchange (feedback and feedforward) between transmitters and receivers so as to achieve IA progressively. This feedback topology is shown to reduce the ...

  3. Balancing Egoism and Altruism on the Interference Channel: The MIMO case

    CERN Document Server

    Ho, Zuleita K M

    2010-01-01

    This paper considers the so-called MIMO interference channel. This situation has relevance in applications such as multi-cell coordination in cellular networks as well as spectrum sharing in cognitive radio networks among others. We address the design of precoding (i.e. beamforming) vectors at each sender with the aim of striking a compromise between beamforming gain at the intended receiver (Egoism) and the mitigation of interference created towards other receivers (Altruism). Combining egoistic and altruistic beamforming has been shown previously to be instrumental to optimizing the rates in a MISO interference channel (i.e. where receivers have no interference canceling capability) . Here we explore these game-theoretic concepts in the more general context of MIMO channels and using the framework of Bayesian games, allowing us to derive (semi-)distributed precoding techniques. We draw parallels with existing work on the MIMO interference channel, including rate-optimizing and interference-alignement precod...

  4. A novel MMSE based codebook construction for MIMO precoded spatial multiplexing with limited feedback

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper deals with the design and performance analysis of the transmission precoder optimization for multiple-input multiple-output (MIMO) systems with limited feedback of channel state information (CSI). We assume that the receiver can get perfect channel knowledge by channel estimation while the transmitter only has partial channel knowledge from limited feedback. We present a minimum mean square error (MMSE) criterion based codebook construction algorithm for MIMO precoded spatial multiplexing systems under a specific average power constraint. The optimal transmitter structure is employed in this paper. Simulation results show that the MMSE criteria based codebook construction algorithm with hybrid design of power allocation and precoding can achieve better performance than that of equal power allocation based codebook of previous research.

  5. FPGA based Smart Wireless MIMO Control System

    International Nuclear Information System (INIS)

    In our present work, we have successfully designed, and developed an FPGA based smart wireless MIMO (Multiple Input and Multiple Output) system capable of controlling multiple industrial process parameters such as temperature, pressure, stress and vibration etc. To achieve this task we have used Xilin x Spartan 3E FPGA (Field Programmable Gate Array) instead of conventional microcontrollers. By employing FPGA kit to PC via RF transceivers which has a working range of about 100 meters. The developed smart system is capable of performing the control task assigned to it successfully. We have also provided a provision to our proposed system that can be accessed for monitoring and control through the web and GSM as well. Our proposed system can be equally applied to all the hazardous and rugged industrial environments where a conventional system cannot work effectively

  6. FPGA based Smart Wireless MIMO Control System

    Science.gov (United States)

    Usman Ali, Syed M.; Hussain, Sajid; Akber Siddiqui, Ali; Arshad, Jawad Ali; Darakhshan, Anjum

    2013-12-01

    In our present work, we have successfully designed, and developed an FPGA based smart wireless MIMO (Multiple Input & Multiple Output) system capable of controlling multiple industrial process parameters such as temperature, pressure, stress and vibration etc. To achieve this task we have used Xilin x Spartan 3E FPGA (Field Programmable Gate Array) instead of conventional microcontrollers. By employing FPGA kit to PC via RF transceivers which has a working range of about 100 meters. The developed smart system is capable of performing the control task assigned to it successfully. We have also provided a provision to our proposed system that can be accessed for monitoring and control through the web and GSM as well. Our proposed system can be equally applied to all the hazardous and rugged industrial environments where a conventional system cannot work effectively.

  7. On Antenna Design Objectives and the Channel Capacity of MIMO Handsets

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Yanakiev, Boyan; Barrio, Samantha Caporal Del;

    2014-01-01

    The branch correlation coefficient (BCC), the branch power ratio (BPR), and the total mean power (TMP) are often used to characterize the mobile multiple-input multiple- output (MIMO) channel. This work investigates to which degree these parameters are useful for maximizing the channel capacity of...... MIMO handheld devices used in data mode. A statistical point of view is applied, using about 2,800 outdoor to indoor channel sounder measurements obtained with combinations of 10 different handsets, 4-8 test users and a variety of different use cases (UCs). All measurements were made in an urban...

  8. Channel estimation for MIMO-OFDM systems in wireless mobile channels

    Institute of Scientific and Technical Information of China (English)

    Lu Zhen; Ge Jianhua

    2008-01-01

    New training sequences and frame structure are proposed to estimate time-varying channel for multiple-input multiple-output and orthogonal frequency division multiplexing (MIMO-OFDM) systems. The training sequences are modulatable orthogonal polyphase sequences, which have both good autocorrelations and cross-correlations. The channel impulse response (CIR) can be obtained by measuring the correlation between the received training sequence and the locally generated training sequence. The training sequences are used as guard interval instead of cyclic prefix, which not only improve the transmission efficiency but also enable the channel estimator to track time-varying channel. The simulation results show that the proposed method has about 2dB SNR gain over conventional methods in fast time-varying channel.

  9. Compound Outage Probability and Capacity of a Class of Fading MIMO Channels with Channel Distribution Uncertainty

    CERN Document Server

    Ioannou, Ioanna; Loyka, Sergey

    2011-01-01

    Outage probability and capacity of a class of block-fading MIMO channels are considered with partial channel distribution information. Specifically, the channel or its distribution are not known but the latter is known to belong to a class of distributions where each member is within a certain distance (uncertainty) from a nominal distribution. Relative entropy is used as a measure of distance between distributions. Compound outage probability defined as min (over the transmit signal distribution) -max (over the channel distribution class) outage probability is introduced and investigated. This generalizes the standard outage probability to the case of partial channel distribution information. Compound outage probability characterization (via one-dimensional convex optimization), its properties and approximations are given. It is shown to have two-regime behavior: when the nominal outage probability decreases (e.g. by increasing the SNR), the compound outage first decreases linearly down to a certain threshol...

  10. Outage capacity and outage rate performance of MIMO free-space optical system over strong turbulence channel

    Science.gov (United States)

    Hasan, Omar M.; Taha, Mohamed; Abu Sharkh, Osama

    2016-06-01

    In this paper, we investigate outage capacity, outage probability, and outage rate performance of multiple-input multiple-output (MIMO) free-space optical system operating over strong turbulence channels. The MIMO optical system employs intensity modulation direct detection with on-off signaling, and equal gain combining technique at the receiver. We derived novel closed-form expressions for three system metrics, namely, outage capacity, outage probability, and outage rate. Expressions derived here are based on the generalized Gamma-Gamma channel model, which is based on scintillation theory that assumes that the irradiance of the received optical wave is modeled as the product of small-scale and large-scale turbulence eddies. The results are evaluated for different values of received signal-to-noise ratios, strong turbulence conditions, and several values of transmit/receive diversity.

  11. BER PERFORMANCE IMPROVEMENT USING MIMO TECHNIQUE OVER RAYLEIGH WIRELESS CHANNEL with DIFFERENT EQUALIZERS

    Directory of Open Access Journals (Sweden)

    Amit Kumar Sahu

    2012-10-01

    Full Text Available Wireless communication using Multiple-Input Multiple-Output (MIMO links has emerged as one of the most significant breakthroughs in modern communications because of the huge capacity and reliabilitygains promised even in worst fading environment. This paper presents an overview of some important behaviors of MIMO systems under Rayleigh channel environments. This work describes the basic ideasof MIMO transmission systems and focused and investigated the BER performance. All analysis was performed under ideal identical independent fading conditions by the use of MATLAB. At the initialstage of the work we related the SNR and the error performance of MIMO systems with the diversity schemes, in the later part of the paper, implementations of different equalizers are also verified for the improvement of the BER performance. Each chapter is rounded by a number of simulations to deepen the understanding of the performance with the use of multiple antennas and equalizers in wirelesscommunication over Rayleigh wireless radio channels. MIMO fading channels are correlated to observe mutual coupling between antenna elements. Receiver diversity is analyzed especially with the MaximalRatio Combining(MRC technique and fair comparison is done with Equal Gain Combining(EGC and Selection- Combing(SC. Further study is done with integration of Maximum Likelihood (ML, Maximum Mean Square Equalization(MMSE and Zero Forcing(ZF. All the results obtained aresimulated by using the MATLAB, under Rayleigh channel conditions.

  12. Wideband MIMO Channel Capacity Analysis in Multi-probe Anechoic Chamber Setups

    DEFF Research Database (Denmark)

    Fan, Wei; Kyosti, Pekka; Nielsen, Jesper Ødum;

    2016-01-01

    been used to determine the test area size for a limited number of probes. However, it is desirable that the test area size is defined in terms of data rate deviation of the simulated channel in the laboratory from that of the target channel model. This paper reports MIMO capacity analysis results for...

  13. On the BER and capacity analysis of MIMO MRC systems with channel estimation error

    KAUST Repository

    Yang, Liang

    2011-10-01

    In this paper, we investigate the effect of channel estimation error on the capacity and bit-error rate (BER) of a multiple-input multiple-output (MIMO) transmit maximal ratio transmission (MRT) and receive maximal ratio combining (MRC) systems over uncorrelated Rayleigh fading channels. We first derive the ergodic (average) capacity expressions for such systems when power adaptation is applied at the transmitter. The exact capacity expression for the uniform power allocation case is also presented. Furthermore, to investigate the diversity order of MIMO MRT-MRC scheme, we derive the BER performance under a uniform power allocation policy. We also present an asymptotic BER performance analysis for the MIMO MRT-MRC system with multiuser diversity. The numerical results are given to illustrate the sensitivity of the main performance to the channel estimation error and the tightness of the approximate cutoff value. © 2011 IEEE.

  14. Sphere decoding complexity exponent for decoding full rate codes over the quasi-static MIMO channel

    CERN Document Server

    Jalden, Joakim

    2011-01-01

    In the setting of quasi-static multiple-input multiple-output (MIMO) channels, we consider the high signal-to-noise ratio (SNR) asymptotic complexity required by the sphere decoding (SD) algorithm for decoding a large class of full rate linear space-time codes. With SD complexity having random fluctuations induced by the random channel, noise and codeword realizations, the introduced SD complexity exponent manages to concisely describe the computational reserves required by the SD algorithm to achieve arbitrarily close to optimal decoding performance. Bounds and exact expressions for the SD complexity exponent are obtained for the decoding of large families of codes with arbitrary performance characteristics. For the particular example of decoding the recently introduced threaded cyclic division algebra (CDA) based codes -- the only currently known explicit designs that are uniformly optimal with respect to the diversity multiplexing tradeoff (DMT) -- the SD complexity exponent is shown to take a particularly...

  15. Channel Characteristics and Performance of MIMO E-SDM Systems in an Indoor Time-Varying Fading Environment

    Directory of Open Access Journals (Sweden)

    Nishimoto Hiroshi

    2010-01-01

    Full Text Available Multiple-input multiple-output (MIMO systems employ advanced signal processing techniques. However, the performance is affected by propagation environments and antenna characteristics. The main contributions of the paper are to investigate Doppler spectrum based on measured data in a typical meeting room and to evaluate the performance of MIMO systems based on an eigenbeam-space division multiplexing (E-SDM technique in an indoor time-varying fading environment, which has various distributions of scatterers, line-of-sight wave existence, and mutual coupling effect among antennas. We confirm that due to the mutual coupling among antennas, patterns of antenna elements are changed and different from an omnidirectional one of a single antenna. Results based on the measured channel data in our measurement campaigns show that received power, channel autocorrelation, and Doppler spectrum are dependent not only on the direction of terminal motion but also on the antenna configuration. Even in the obstructed-line-of-sight environment, observed Doppler spectrum is quite different from the theoretical U-shaped Jakes one. In addition, it has been also shown that a channel change during the time interval between the transmit weight matrix determination and the actual data transmission can degrade the performance of MIMO E-SDM systems.

  16. Channel estimation for MIMO-OFDM systems in mobile wireless channels

    Institute of Scientific and Technical Information of China (English)

    WU Yun; LUO Han-wen; SONG Wen-tao

    2008-01-01

    A channel estimation method is proposed for multiple-input multiple-output orthogonal frequency di-vision multiplexing (MIMO-OFDM) systems in time-varying fading channels. In this method, a decision-direct-ed space-ahernating generalized expectation-maximization (SAGE) algorithm is introduced to the tracking of time-varying fading. In order to improve the estimation performance of the SAGE algorithm, a low rank approxi-mation method is presented by using the signal subspaee of the channel frequency autocorrelation matrix. The study reveals that this method can be incorporated into the SAGE algorithm. Furthermore, a modified fast sub-space tracking algorithm is given to adaptively estimate the signal subspace by utilizing training OFDM blocks sent at regular interval. Simulation results demonstrate the considerable benefits of the proposed channel estima-tion method.

  17. Space-Time Water-Filling for Composite MIMO Fading Channels

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available We analyze the ergodic capacity and channel outage probability for a composite MIMO channel model, which includes both fast fading and shadowing effects. The ergodic capacity and exact channel outage probability with space-time water-filling can be evaluated through numerical integrations, which can be further simplified by using approximated empirical eigenvalue and maximal eigenvalue distribution of MIMO fading channels. We also compare the performance of space-time water-filling with spatial water-filling. For MIMO channels with small shadowing effects, spatial water-filling performs very close to space-time water-filling in terms of ergodic capacity. For MIMO channels with large shadowing effects, however, space-time water-filling achieves significantly higher capacity per antenna than spatial water-filling at low to moderate SNR regimes, but with a much higher channel outage probability. We show that the analytical capacity and outage probability results agree very well with those obtained from Monte Carlo simulations.

  18. Nonconcave Utility Maximisation in the MIMO Broadcast Channel

    Directory of Open Access Journals (Sweden)

    Wolfgang Utschick

    2008-09-01

    Full Text Available The problem of determining an optimal parameter setup at the physical layer in a multiuser, multiantenna downlink is considered. An aggregate utility, which is assumed to depend on the users' rates, is used as performance metric. It is not assumed that the utility function is concave, allowing for more realistic utility models of applications with limited scalability. Due to the structure of the underlying capacity region, a two step approach is necessary. First, an optimal rate vector is determined. Second, the optimal parameter setup is derived from the optimal rate vector. Two methods for computing an optimal rate vector are proposed. First, based on the differential manifold structure offered by the boundary of the MIMO BC capacity region, a gradient projection method on the boundary is developed. Being a local algorithm, the method converges to a rate vector which is not guaranteed to be a globally optimal solution. Second, the monotonic structure of the rate space problem is exploited to compute a globally optimal rate vector with an outer approximation algorithm. While the second method yields the global optimum, the first method is shown to provide an attractive tradeoff between utility performance and computational complexity.

  19. Nonconcave Utility Maximisation in the MIMO Broadcast Channel

    Science.gov (United States)

    Brehmer, Johannes; Utschick, Wolfgang

    2008-12-01

    The problem of determining an optimal parameter setup at the physical layer in a multiuser, multiantenna downlink is considered. An aggregate utility, which is assumed to depend on the users' rates, is used as performance metric. It is not assumed that the utility function is concave, allowing for more realistic utility models of applications with limited scalability. Due to the structure of the underlying capacity region, a two step approach is necessary. First, an optimal rate vector is determined. Second, the optimal parameter setup is derived from the optimal rate vector. Two methods for computing an optimal rate vector are proposed. First, based on the differential manifold structure offered by the boundary of the MIMO BC capacity region, a gradient projection method on the boundary is developed. Being a local algorithm, the method converges to a rate vector which is not guaranteed to be a globally optimal solution. Second, the monotonic structure of the rate space problem is exploited to compute a globally optimal rate vector with an outer approximation algorithm. While the second method yields the global optimum, the first method is shown to provide an attractive tradeoff between utility performance and computational complexity.

  20. Jamming Games in the MIMO Wiretap Channel With an Active Eavesdropper

    CERN Document Server

    Mukherjee, Amitav

    2010-01-01

    This paper investigates reliable and covert transmission strategies in a MIMO wiretap channel with a transmitter, receiver and an adversarial wiretapper, each equipped with multiple antennas. In a departure from existing work, the wiretapper possesses the dual capability to act either as a passive eavesdropper or as an active jammer, under a halfduplex constraint. The transmitter therefore faces a choice between allocating all of its power for data, or broadcasting artificial noise along with the information signal in order to selectively jam the eavesdropper (assuming its instantaneous channel state is unknown). To examine the resulting tradeoffs for both agents, we model the network as a two-person zero-sum game with the ergodic MIMO secrecy rate as the payoff function. We first quantify and rank the various possible MIMO secrecy rate outcomes of the actions available to each player, and derive asymptotic expressions for the same. We then examine conditions for the existence of pure and mixed Nash equilibri...

  1. On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

    KAUST Repository

    Park, Kihong

    2013-04-01

    In this paper, we consider resource allocation method in the visible light communication. It is challenging to achieve high data rate due to the limited bandwidth of the optical sources. In order to increase the spectral efficiency, we design a suitable multiple-input multiple-output (MIMO) system utilizing spatial multiplexing based on singular value decomposition and adaptive modulation. More specifically, after explaining why the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels, we theoretically derive a power allocation method for an arbitrary number of transmit and receive antennas for optical wireless MIMO systems. Based on three key constraints: the nonnegativity of the intensity-modulated signal, the aggregate optical power budget, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size. Based on some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency at the expense of an increased computational complexity in comparison to a simple method that allocates the optical power equally among all the data streams. © 2013 IEEE.

  2. Effect of Attitude Change on Unmanned Aerial Vehicle MIMO Channel Capacity%姿态变化对无人机MIMO信道容量的影响

    Institute of Scientific and Technical Information of China (English)

    陈登伟; 高喜俊; 许鑫; 齐伟伟

    2015-01-01

    考虑无人机多天线通信需求,在无人机上以圆阵方式布置4元天线。为分析无人机多入多出( Multi⁃Input Multi⁃Output, MIMO)通信系统,建立了统一的坐标系,并构建了基于四发两收的无人机MIMO三维GBSBCM信道模型,采用信道矩阵分解、信道系数归一化的方法,推导了无人机的MIMO平均信道相关矩阵。仿真分析了无人机姿态变化参数对无人机MIMO信道容量的影响,对合理调整无人机姿态参数来提高无人机MIMO通信容量提供理论参考。%Aiming at the demand of Unmanned Aerial Vehicle for Multi⁃Input Multi⁃Output ( UAV⁃MIMO) communication,four antennas are laid as circular array in UAV.To analyze UAV⁃MIMO communication system,the uniform coordinate is built,and also the 3D⁃GBSBCM ( Geometrically Based Single Bounce Cylinder Model) channel model of UAV⁃MIMO based on four transmitters and two receivers is constructed.The method of channel matrix factorization and channel coefficient normalization are put forward to deduce the average channel correlation matrix of UAV MIMO.At last,the effect of UAV attitude change parameters on UAV MIMO channel capacity is simulated and analyzed.The simulation results provides theory reference for improving UAV⁃MIMO system capacity by changing the attitude parameters.

  3. MIMO capacity for deterministic channel models: sublinear growth

    DEFF Research Database (Denmark)

    Bentosela, Francois; Cornean, Horia; Marchetti, Nicola

    2013-01-01

    This is the second paper by the authors in a series concerned with the development of a deterministic model for the transfer matrix of a MIMO system. In our previous paper, we started from the Maxwell equations and described the generic structure of such a deterministic transfer matrix. In the...

  4. Channel Estimation and Data Detection for MIMO Systems under Spatially and Temporally Colored Interference

    Directory of Open Access Journals (Sweden)

    Yi Song

    2004-05-01

    Full Text Available The impact of interference on multiple-input multiple-output (MIMO systems has recently attracted interest. Most studies of channel estimation and data detection for MIMO systems consider spatially and temporally white interference at the receiver. In this paper, we address channel estimation, interference correlation estimation, and data detection for MIMO systems under both spatially and temporally colored interference. We examine the case of one dominant interferer in which the data rate of the desired user could be the same as or a multiple of that of the interferer. Assuming known temporal interference correlation as a benchmark, we derive maximum likelihood (ML estimates of the channel matrix and spatial interference correlation matrix, and apply these estimates to a generalized version of the Bell Labs Layered Space-Time (BLAST ordered data detection algorithm. We then investigate the performance loss by not exploiting interference correlation. For a (5,5 MIMO system undergoing independent Rayleigh fading, we observe that exploiting both spatial and temporal interference correlation in channel estimation and data detection results in potential gains of 1.5 dB and 4 dB for an interferer operating at the same data rate and at half the data rate, respectively. Ignoring temporal correlation, it is found that spatial correlation accounts for about 1 dB of this gain.

  5. Outage and Capacity Performance Evaluation of Distributed MIMO Systems over a Composite Fading Channel

    Directory of Open Access Journals (Sweden)

    Wenjie Peng

    2014-01-01

    Full Text Available The exact closed-form expressions regarding the outage probability and capacity of distributed MIMO (DMIMO systems over a composite fading channel are derived. This is achieved firstly by using a lognormal approximation to a gamma-lognormal distribution when a mobile station (MS in the cell is in a fixed position, and the so-called maximum ratio transmission/selected combining (MRT-SC and selected transmission/maximum ratio combining (ST-MRC schemes are adopted in uplink and downlink, respectively. Then, based on a newly proposed nonuniform MS cell distribution model, which is more consistent with the MS cell hotspot distribution in an actual communication environment, the average outage probability and capacity formulas are further derived. Finally, the accuracy of the approximation method and the rationality of the corresponding theoretical analysis regarding the system performance are proven and illustrated by computer simulations.

  6. MIMO free-space optical communication employing coherent BPOLSK modulation in atmospheric optical turbulence channel with pointing errors

    Science.gov (United States)

    Prabu, K.; Kumar, D. Sriram

    2015-05-01

    An optical wireless communication system is an alternative to radio frequency communication, but atmospheric turbulence induced fading and misalignment fading are the main impairments affecting an optical signal when propagating through the turbulence channel. The resultant of misalignment fading is the pointing errors, it degrades the bit error rate (BER) performance of the free space optics (FSO) system. In this paper, we study the BER performance of the multiple-input multiple-output (MIMO) FSO system employing coherent binary polarization shift keying (BPOLSK) in gamma-gamma (G-G) channel with pointing errors. The BER performance of the BPOLSK based MIMO FSO system is compared with the single-input single-output (SISO) system. Also, the average BER performance of the systems is analyzed and compared with and without pointing errors. A novel closed form expressions of BER are derived for MIMO FSO system with maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques. The analytical results show that the pointing errors can severely degrade the performance of the system.

  7. RLS channel estimation with adaptive forgetting factor in space-time coded MIMO-OFDM systems

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Considering that channel estimation plays a crucial role in coherent detection, this paper addresses a method of Recursive-least-squares (RLS) channel estimation with adaptive forgetting factor in wireless space-time coded multiple-input and multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. Because there are three different forgetting factor scenarios including adaptive, two-step and conventional ones applied to RLS channel estimation, this paper describes the principle of RLS channel estimation and analyzes the impact of different forgetting factor scenarios on the performances of RLS channel estimation. Simulation results proved that the RLS algorithm with adaptive forgetting factor (RLS-A) outperformed that with two-step forgetting factor (RLS-T) or with conventional forgetting factor (RLS-C) in both estimation accuracy and robustness over the multiple-input multiple-output (MIMO) channel, i.e., a wide-sense stationary uncorrelated scattering (WSSUS) and frequency-selective slowly fading channel. Hence, we can employ the RLS-A method by adjusting forgetting factor adaptively to track and estimate channel state parameters successfully in space-time coded MIMO-OFDM systems.

  8. Low SNR capacity for MIMO Rician and Rayleigh-product fading channels with single co-channel interferer and noise

    KAUST Repository

    Zhong, Caijun

    2010-09-01

    This paper studies the ergodic capacity of multiple-input multiple-output (MIMO) systems with a single co-channel interferer in the low signal-to-noise-ratio (SNR) regime. Two MIMO models namely Rician and Rayleigh-product channels are investigated. Exact analytical expressions for the minimum energy per information bit, {Eb/N0min, and wideband slope, S0, are derived for both channels. Our results show that the minimum energy per information bit is the same for both channels while their wideband slopes differ significantly. Further, the impact of the numbers of transmit and receive antennas, the Rician K factor, the channel mean matrix and the interference-to-noise-ratio (INR) on the capacity, is addressed. Results indicate that interference degrades the capacity by increasing the required minimum energy per information bit and reducing the wideband slope. Simulation results validate our analytical results. © 2010 IEEE.

  9. Closed Form Secrecy Capacity of MIMO Wiretap Channels with Two Transmit Antennas

    CERN Document Server

    Li, Jiangyuan

    2011-01-01

    A Gaussian multiple-input multiple-output (MIMO) wiretap channel model is considered. The input is a two-antenna transmitter, while the outputs are the legitimate receiver and an eavesdropper, both equipped with multiple antennas. All channels are assumed to be known. The problem of obtaining the optimal input covariance matrix that achieves secrecy capacity subject to a power constraint is addressed, and a closed-form expression for the secrecy capacity is obtained.

  10. CHANNEL ESTIMATION WITH CIRCULARLY SLIPPING WINDOW IN MIMO-OFDM SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Ge Qihong; Sun Zhi; Yang Huazhong

    2006-01-01

    Channel estimation is very important for MIMO (Multiple Input Multiple Output) OFDM (Orthogonal Frequency Division Multiplexing) systems, but its precision is reduced due to the noise in channel. In this letter, circularly slipping window is introduced to resist the noise. It can be proved by simulation that with the same channel model, optimal slipping window length is the same with different vehicle speed. MSE (Minimum Square Error) of channel is greatly reduced with circularly slipping window, and performance of the system is closed to that with correct channel estimation.

  11. SUBSPACE-BASED NOISE VARIANCE AND SNR ESTIMATION FOR MIMO OFDM SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper proposes a subspace-based noise variance and Signal-to-Noise Ratio (SNR) estimation algorithm for Multi-Input Multi-Output (MIMO) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems. The special training sequences with the property of orthogonality and phase shift orthogonality are used in pilot tones to obtain the estimated channel correlation matrix. Partitioning the observation space into a delay subspace and a noise subspace, we achieve the measurement of noise variance and SNR.Simulation results show that the proposed estimator can obtain accurate and real-time measurements of the noise variance and SNR for various multipath fading channels, demonstrating its strong robustness against different channels.

  12. Improving Performance of Wi-Fi by Compact MIMO Systems by using Gama Frequency-Selective Fading Channels

    OpenAIRE

    Sudesh Gupta; Rajesh Nema; Puran Gour

    2011-01-01

    In this paper we propose a compact MIMO system in frequency-selective fading channels which improves the performance of Wireless Media. A MIMO beam forming system model with mutual coupling and matching network is proposed to cope with frequency-selective fading channels. The overall system proposed transfer matrix is derived using Z-parameter method. The system using the transform matrix which accepts the relay and the delay matrix for the computation. Then apply the diversity criteria by wh...

  13. Utility of Beamforming Strategies for Secrecy in Multiuser MIMO Wiretap Channels

    CERN Document Server

    Mukherjee, Amitav

    2009-01-01

    This paper examines linear beamforming methods for secure communications in a multiuser wiretap channel with a single transmitter, multiple legitimate receivers, and a single eavesdropper, where all nodes are equipped with multiple antennas. No information regarding the eavesdropper is presumed at the transmitter, and we examine both the broadcast MIMO downlink with independent information, and the multicast MIMO downlink with common information for all legitimate receivers. In both cases the information signal is transmitted with just enough power to guarantee a certain SINR at the desired receivers, while the remainder of the power is used to broadcast artificial noise. The artificial interference selectively degrades the passive eavesdropper's signal while remaining orthogonal to the desired receivers. We analyze the confidentiality provided by zero-forcing and optimal minimum-power beamforming designs for the broadcast channel, and optimal minimum-MSE beamformers for the multicast channel. Numerical simul...

  14. An MMSE Approach to the Secrecy Capacity of the MIMO Gaussian Wiretap Channel

    Directory of Open Access Journals (Sweden)

    Ronit Bustin

    2009-01-01

    Full Text Available This paper provides a closed-form expression for the secrecy capacity of the multiple-input multiple output (MIMO Gaussian wiretap channel, under a power-covariance constraint. Furthermore, the paper specifies the input covariance matrix required in order to attain the capacity. The proof uses the fundamental relationship between information theory and estimation theory in the Gaussian channel, relating the derivative of the mutual information to the minimum mean-square error (MMSE. The proof provides the missing intuition regarding the existence and construction of an enhanced degraded channel that does not increase the secrecy capacity. The concept of enhancement has been used in a previous proof of the problem. Furthermore, the proof presents methods that can be used in proving other MIMO problems, using this fundamental relationship.

  15. Time-domain training sequences design for MIMO OFDM channel estimation

    Institute of Scientific and Technical Information of China (English)

    Zhen LU; Jian-hua GE

    2008-01-01

    This paper describes a Least Squares (LS) channel estimation scheme for MIMO OFDM systems based on time-domain training sequence. We first compute the minimum mean square error (MSE) of the LS channel estimation, and then derive the optimal criteria of the training sequence with respect to the minimum MSE. It is shown that optimal time-domain training sequence should satisfy two criteria. First, the autocorrelation of the sequence transmitted from the same antenna is an impulse function in a region longer than the channel maximum delay. Second, the cross-correlation between sequences transmitted from different antennas is zero in this region. Simulation results show that the estimator using optimal time-domain training sequences has better performance than that using optimal frequency training sequence at low signal-to-noise ratio (SNR). To reduce the training overhead, a suboptimal training sequence is also proposed. Comparing with optimal training sequence, it has low computation complexity and high transmission efficiency at the expense of little performance degradation.

  16. Compressive sensing for feedback reduction in MIMO broadcast channels

    KAUST Repository

    Eltayeb, Mohammed E.

    2014-09-01

    In multi-antenna broadcast networks, the base stations (BSs) rely on the channel state information (CSI) of the users to perform user scheduling and downlink transmission. However, in networks with large number of users, obtaining CSI from all users is arduous, if not impossible, in practice. This paper proposes channel feedback reduction techniques based on the theory of compressive sensing (CS), which permits the BS to obtain CSI with acceptable recovery guarantees under substantially reduced feedback overhead. Additionally, assuming noisy CS measurements at the BS, inexpensive ways for improving post-CS detection are explored. The proposed techniques are shown to reduce the feedback overhead, improve CS detection at the BS, and achieve a sum-rate close to that obtained by noiseless dedicated feedback channels.

  17. Asymptotic Performance of Linear Receivers in MIMO Fading Channels

    CERN Document Server

    Kumar, K Raj; Moustakas, A L

    2008-01-01

    Linear receivers are considered as an attractive low-complexity alternative to optimal processing for multi-antenna MIMO communications. In this paper we characterize the performance of MIMO linear receivers in two different asymptotic regimes. For fixed number of antennas, we investigate the Diversity-Multiplexing Tradeoff (DMT), which captures the outage probability (decoding block-error probability) in the limit of high SNR. For fixed SNR, we characterize the outage probability for a large (but finite) number of antennas. As far as the DMT is concerned, we report a negative result: we show that both linear Zero-Forcing (ZF) and linear Minimum Mean-Square Error (MMSE) receivers achieve the same DMT, which is largely suboptimal even though outer coding and decoding is performed across the antennas. We also provide an approximate quantitative analysis of the different behavior of the MMSE and ZF receivers at finite rate and non-asymptotic SNR, and show that while the ZF receiver achieves poor diversity at any...

  18. A proof of the log-concavity conjecture related to the computation of the ergodic capacity of MIMO channels

    Energy Technology Data Exchange (ETDEWEB)

    Gurvitis, Leonid [Los Alamos National Laboratory

    2009-01-01

    An upper bound on the ergodic capacity of MIMO channels was introduced recently in [1]. This upper bound amounts to the maximization on the simplex of some multilinear polynomial p({lambda}{sub 1}, ..., {lambda}{sub n}) with non-negative coefficients. In general, such maximizations problems are NP-HARD. But if say, the functional log(p) is concave on the simplex and can be efficiently evaluated, then the maximization can also be done efficiently. Such log-concavity was conjectured in [1]. We give in this paper self-contained proof of the conjecture, based on the theory of H-Stable polynomials.

  19. Solutions for the MIMO Gaussian Wiretap Channel With a Cooperative Jammer

    Science.gov (United States)

    Fakoorian, S. Ali A.; Swindlehurst, A. Lee

    2011-10-01

    We study the Gaussian MIMO wiretap channel with a transmitter, a legitimate receiver, an eavesdropper and an external helper, each equipped with multiple antennas. The transmitter sends confidential messages to its intended receiver, while the helper transmits jamming signals independent of the source message to confuse the eavesdropper. The jamming signal is assumed to be treated as noise at both the intended receiver and the eavesdropper. We obtain a closed-form expression for the structure of the artificial noise covariance matrix that guarantees no decrease in the secrecy capacity of the wiretap channel. We also describe how to find specific realizations of this covariance matrix expression that provide good secrecy rate performance, even when there is no non-trivial null space between the helper and the intended receiver. Unlike prior work, our approach considers the general MIMO case, and is not restricted to SISO or MISO scenarios.

  20. Solutions for the MIMO Gaussian Wiretap Channel with a Cooperative Jammer

    CERN Document Server

    Fakoorian, S Ali A

    2011-01-01

    We study the Gaussian MIMO wiretap channel with a transmitter, a legitimate receiver, an eavesdropper and an external helper, each equipped with multiple antennas. The transmitter sends confidential messages to its intended receiver, while the helper transmits jamming signals independent of the source message to confuse the eavesdropper. The jamming signal is assumed to be treated as noise at both the intended receiver and the eavesdropper. We obtain a closed-form expression for the structure of the artificial noise covariance matrix that guarantees no decrease in the secrecy capacity of the wiretap channel. We also describe how to find specific realizations of this covariance matrix expression that provide good secrecy rate performance, even when there is no non-trivial null space between the helper and the intended receiver. Unlike prior work, our approach considers the general MIMO case, and is not restricted to SISO or MISO scenarios.

  1. Symbol Estimation Algorithm for MIMO Underwater Acoustic Communication System Based on Multiplicative Noise Model

    Directory of Open Access Journals (Sweden)

    Ling Zhang

    2015-01-01

    Full Text Available The stochastic and time-varying underwater acoustic (UWA channels are usually affected by serious multipath delays, energy loss and distortion factors, thus making the modeling and estimation of the UWA channel challenging problems in the research community. Based on the analysis of the UWA channel, the system with multiplicative noise (SMN model is established to characterize the complicated factors such as random time-variation, nonlinearity, and energy attenuation. As to the multiple-input multiple-output (MIMO UWA communication, the complicated SMN model is established for MIMO UWA channels; based on which, the transmitted symbols are estimated according to the optimal recursive filtering algorithm. The algorithm is derived based on the projection theorem, which is optimal in the sense of linear minimum variance, and can overcome the intersymbol interference and noise pollution efficiently. The optimal algorithm is computed recursively, which has the advantage of computation-efficiency and can track the random variation of the fast time-varying channel gain dynamically. Simulation results have validated the effectiveness of the algorithm. The model and the algorithm can be extended flexibly to certain practical problems, such as the joint channel and symbol estimation in underwater acoustic communication systems.

  2. Limited feedback MIMO techniques for temporally correlated channels and linear receivers

    OpenAIRE

    Zacarías Brach, Eduardo

    2012-01-01

    Advanced mobile wireless networks will make extensive use of multiantenna (MIMO) transceivers to comply with high requirements of data rates and reliability. The use of feedback channels is of paramount importance to achieve this goal in systems employing frequency division duplexing (FDD). The design of the feedback mechanism is challenging due to the severe constraints imposed by computational complexity and feedback bandwidth restrictions. This thesis addresses the design of transmissio...

  3. Antenna Array Structures Effect on Water-Filling Capacity of Indoor NLOS MIMO Channel

    Institute of Scientific and Technical Information of China (English)

    L(U) Jian-gang; L(U) Ying-hua; DU Juan; LI Yun-zhuang; WANG Xu-ying

    2005-01-01

    A 2-D Shooting and Bouncing Ray-tracing method (SBR) is used to analyze the different antenna array structure effect on the water-filling Capacity Complementary Cumulative Distribution Functions (CCDFS) of indoor Non-Line-of-Sight (NLOS) Multiple-Input Multiple-Output (MIMO) channel. The results have shown that in NLOS indoor environment different antenna array structures affect on the CCDFS differently. The CCDFS of MIMO systems with antenna spacing 5λ change slightly with antenna array structures and all approach the in independent and identically distribution (i.i.d.) rayleigh channel water-filling capacity. When antenna spacing decreased to 0.5λ, the capacities of MIMO systems drop also, and change with antenna array structures greatly. The results on outage water-filling capacity also show that there exist a fixed relationship that i.i.d. rayleigh channel capacity is larger than the capacity equipped with linear antenna array which is larger than the capacity equipped with rectangular antenna array and the capacity equipped with circular antenna array.

  4. Meandered Monopoles for 700 MHz LTE Handsets and Improved MIMO Channel Capacity Performance

    Directory of Open Access Journals (Sweden)

    I. Dioum

    2011-12-01

    Full Text Available In this paper, we present the design and the measurement of MIMO meandered monopole antennas and the computation of their channel capacity performance. The initial proposed handset-system is composed of a meandered monopole operating in the LTE 700 MHz band, connected to a parasitic radiating element for the upper 2.5 GHz LTE band. Two antennas of the same kind are then closely positioned on the same 120x50 mm2 Printed Circuit Board (PCB. A neutralization line connects the two antennas to enhance their port-to-port isolation in the 700 MHz band. The computation of the channel capacity performance in this band is based on propagation simulations performed with the GRIMM model from the CREMANT. Two system-prototypes are evaluated: one with the neutralization line for enhanced port-to-port isolation and a second without the neutralization exhibiting poor antenna-to-antenna isolation. It is demonstrated that the neutralization technique helps in giving a minimum improvement of 12% of the capacity performance of the handset-system, and a maximum improvement 46%, in the chosen environment.

  5. On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

    KAUST Repository

    Park, Kihong

    2011-07-01

    Visible light communication (VLC) using optical sources which can be simultaneously utilized for illumination and communication is currently an attractive option for wireless personal area network. Improving the data rate in optical wireless communication system is challenging due to the limited bandwidth of the optical sources. In this paper, we design the singular value decomposition (SVD)- based multiplexing multiple-input multiple-output (MIMO) system to support two data streams in optical wireless channels. Noting that the conventional allocation method in radio frequency (RF) MIMO channels cannot be applied directly to the optical intensity channels, we propose a novel method to allocate the optical power, the offset value and the modulation size for maximum sum rate under the constraints of the nonnegativity of the modulated signals, the aggregate optical power and the bit error rate (BER) requirement. The simulation results show that the proposed allocation method gives the better performance than the method to allocate the optical power equally for each data stream. © 2011 IEEE.

  6. The Degrees of Freedom Regions of Two-User and Certain Three-User MIMO Broadcast Channels with Delayed CSIT

    OpenAIRE

    Vaze, Chinmay S.; Varanasi, Mahesh K.

    2010-01-01

    The degrees of freedom (DoF) region of the fast-fading MIMO (multiple-input multiple-output) Gaussian broadcast channel (BC) is studied when there is delayed channel state information at the transmitter (CSIT). In this setting, the channel matrices are assumed to vary independently across time and the transmitter is assumed to know the channel matrices with some arbitrary finite delay. An outer-bound to the DoF region of the general $K$-user MIMO BC (with an arbitrary number of antennas at ea...

  7. Towards the Secrecy Capacity of the Gaussian MIMO Wire-tap Channel: The 2-2-1 Channel

    CERN Document Server

    Shafiee, Shabnam; Ulukus, Sennur

    2007-01-01

    We find the secrecy capacity of the 2-2-1 Gaussian MIMO wire-tap channel, which consists of a transmitter and a receiver with two antennas each, and an eavesdropper with a single antenna. We determine the secrecy capacity of this channel by proposing an achievable scheme and then developing a tight upper bound that meets the proposed achievable secrecy rate. We show that, for this channel, Gaussian signalling in the form of beam-forming is optimal, and no pre-processing of information is necessary.

  8. Optimum Co-Design for Spectrum Sharing between Matrix Completion Based MIMO Radars and a MIMO Communication System

    Science.gov (United States)

    Li, Bo; Petropulu, Athina P.; Trappe, Wade

    2016-09-01

    Recently proposed multiple input multiple output radars based on matrix completion (MIMO-MC) employ sparse sampling to reduce the amount of data that need to be forwarded to the radar fusion center, and as such enable savings in communication power and bandwidth. This paper proposes designs that optimize the sharing of spectrum between a MIMO-MC radar and a communication system, so that the latter interferes minimally with the former. First, the communication system transmit covariance matrix is designed to minimize the effective interference power (EIP) to the radar receiver, while maintaining certain average capacity and transmit power for the communication system. Two approaches are proposed, namely a noncooperative and a cooperative approach, with the latter being applicable when the radar sampling scheme is known at the communication system. Second, a joint design of the communication transmit covariance matrix and the MIMO-MC radar sampling scheme is proposed, which achieves even further EIP reduction.

  9. Adaptive antenna selection and Tx/Rx beamforming for large-scale MIMO systems in 60 GHz channels

    Directory of Open Access Journals (Sweden)

    Prasad Narayan

    2011-01-01

    Full Text Available Abstract We consider a large-scale MIMO system operating in the 60 GHz band employing beamforming for high-speed data transmission. We assume that the number of RF chains is smaller than the number of antennas, which motivates the use of antenna selection to exploit the beamforming gain afforded by the large-scale antenna array. However, the system constraint that at the receiver, only a linear combination of the receive antenna outputs is available, which together with the large dimension of the MIMO system makes it challenging to devise an efficient antenna selection algorithm. By exploiting the strong line-of-sight property of the 60 GHz channels, we propose an iterative antenna selection algorithm based on discrete stochastic approximation that can quickly lock onto a near-optimal antenna subset. Moreover, given a selected antenna subset, we propose an adaptive transmit and receive beamforming algorithm based on the stochastic gradient method that makes use of a low-rate feedback channel to inform the transmitter about the selected beams. Simulation results show that both the proposed antenna selection and the adaptive beamforming techniques exhibit fast convergence and near-optimal performance.

  10. Fast DOA estimation using wavelet denoising on MIMO fading channel

    Directory of Open Access Journals (Sweden)

    A.V. Meenakshi

    2011-12-01

    Full Text Available This paper presents a tool for the analysis, and simulation of direction-of-arrival (DOA estimation inwireless mobile communication systems over the fading channel. It reviews two methods of Direction ofarrival (DOA estimation algorithm. The standard Multiple Signal Classification (MUSIC can be obtainedfrom the subspace based methods. In improved MUSIC procedure called Cyclic MUSIC, it canautomatically classify the signals as desired and undesired based on the known spectral correlationproperty and estimate only the desired signal’s DOA. In this paper, the DOA estimation algorithm usingthe de-noising pre-processing based on time-frequency conversion analysis was proposed, and theperformances were analyzed. This is focused on the improvement of DOA estimation at a lower SNR andinterference environment. This paper provides a fairly complete image of the performance and statisticalefficiency of each of above two methods with QPSK signal.

  11. Fast DOA estimation using wavelet denoising on MIMO fading channel

    CERN Document Server

    Meenakshi, A V; Kayalvizhi, R; Asha, S

    2011-01-01

    This paper presents a tool for the analysis, and simulation of direction-of-arrival (DOA) estimation in wireless mobile communication systems over the fading channel. It reviews two methods of Direction of arrival (DOA) estimation algorithm. The standard Multiple Signal Classification (MUSIC) can be obtained from the subspace based methods. In improved MUSIC procedure called Cyclic MUSIC, it can automatically classify the signals as desired and undesired based on the known spectral correlation property and estimate only the desired signal's DOA. In this paper, the DOA estimation algorithm using the de-noising pre-processing based on time-frequency conversion analysis was proposed, and the performances were analyzed. This is focused on the improvement of DOA estimation at a lower SNR and interference environment. This paper provides a fairly complete image of the performance and statistical efficiency of each of above two methods with QPSK signal.

  12. On the performance of Golden space-time trellis coded modulation over MIMO block fading channels

    CERN Document Server

    Viterbo, Emanuele

    2007-01-01

    The Golden space-time trellis coded modulation (GST-TCM) scheme was proposed in \\cite{Hong06} for a high rate $2\\times 2$ multiple-input multiple-output (MIMO) system over slow fading channels. In this letter, we present the performance analysis of GST-TCM over block fading channels, where the channel matrix is constant over a fraction of the codeword length and varies from one fraction to another, independently. In practice, it is not useful to design such codes for specific block fading channel parameters and a robust solution is preferable. We then show both analytically and by simulation that the GST-TCM designed for slow fading channels are indeed robust to all block fading channel conditions.

  13. Comparison between MC-CDMA and CDMA-OFDM/OQAM systems in presence of MIMO channel

    OpenAIRE

    Radhia Gharsallah; Ridha Bouallegue

    2012-01-01

    In this paper, we present a comparison between MC-CDMA and CDMA-OFDM/OQAM systems in the case of MIMO channel. The advanced Multi Carrier CDMA OFDM/OQAM modulation is a combination of CDMA and OFDM/OQAM. This combination takes advantages from multicarrier modulation and spread spectrum. Indeed, the use of OFDM has proved its ability to fight against frequency selective channels but the insertion of guard interval yields spectral efficiency loss and sensitivity to frequency dispersion due to t...

  14. Performance Analysis of Virtual MIMO Relaying Schemes Based on Detect–Split–Forward

    KAUST Repository

    Al-Basit, Suhaib M.

    2014-10-29

    © 2014, Springer Science+Business Media New York. Virtual multi-input multi-output (vMIMO) schemes in wireless communication systems improve coverage, throughput, capacity, and quality of service. In this paper, we propose three uplink vMIMO relaying schemes based on detect–split–forward (DSF). In addition, we investigate the effect of several physical parameters such as distance, modulation type and number of relays. Furthermore, an adaptive vMIMO DSF scheme based on VBLAST and STBC is proposed. In order to do that, we provide analytical tools to evaluate the performance of the propose vMIMO relaying scheme.

  15. Iterative Soft Decision Based Complex K-best MIMO Decoder

    Directory of Open Access Journals (Sweden)

    Mehnaz Rahman

    2015-11-01

    Full Text Available This paper presents an iterative soft decision based complex multiple input multiple output (MIMO decoding algorithm, which reduces the complexity of Maximum Likelihood (ML detector. We develop a novel iterative complex K-best decoder exploiting the techniques of lattice reduction for 8×8 MIMO. Besides list size, a new adjustable variable has been introduced in order to control the on-demand child expansion. Following this method, we obtain 6.9 to 8.0 dB improvement over real domain K-best decoder and 1.4 to 2.5 dB better performance compared to iterative conventional complex decoder for 4th iteration and 64-QAM modulation scheme. We also demonstrate the significance of new parameter on bit error rate. The proposed decoder not only increases the performance, but also reduces the computational complexity to a certain level.

  16. Estimation over MIMO Fading Channels: Outage and Diversity Analysis

    OpenAIRE

    Parseh, Reza

    2016-01-01

    In this thesis, estimation of signals over fading channels for analog uncoded transmission is considered. In communication settings with tight delay requirements, e.g. in real-time control over wireless fading channels and vehicle-to-vehicle communication, the use of efficient and therefore long channel codes for reliability is not possible. Without channel codes, one needs to seek out alternative techniques. One such technique is to send uncompressed discrete-time source samples ...

  17. Emulating Realistic Bidirectional Spatial Channels for MIMO OTA Testing

    DEFF Research Database (Denmark)

    Fan, Wei; Kyösti, Pekka; Nielsen, Jesper Ødum;

    2015-01-01

    downlink channel models, whereas uplink channel is often modeled as free space line-of-sight channel without fading. Modeling realistic bidirectional (i.e., both uplink and downlink) propagation environments is essential to evaluate any bidirectional communication systems. There have been works stressing...... configurations) in the uplink and downlink. The simulation results are further supported by measurements in a practical MPAC setup. The proposed algorithm is shown to be a valid method to emulate bidirectional spatial channel models....

  18. Cross-layer designed adaptive modulation algorithm with packet combining and truncated ARQ over MIMO Nakagami fading channels

    KAUST Repository

    Aniba, Ghassane

    2011-04-01

    This paper presents an optimal adaptive modulation (AM) algorithm designed using a cross-layer approach which combines truncated automatic repeat request (ARQ) protocol and packet combining. Transmissions are performed over multiple-input multiple-output (MIMO) Nakagami fading channels, and retransmitted packets are not necessarily modulated using the same modulation format as in the initial transmission. Compared to traditional approach, cross-layer design based on the coupling across the physical and link layers, has proven to yield better performance in wireless communications. However, there is a lack for the performance analysis and evaluation of such design when the ARQ protocol is used in conjunction with packet combining. Indeed, previous works addressed the link layer performance of AM with truncated ARQ but without packet combining. In addition, previously proposed AM algorithms are not optimal and can provide poor performance when packet combining is implemented. Herein, we first show that the packet loss rate (PLR) resulting from the combining of packets modulated with different constellations can be well approximated by an exponential function. This model is then used in the design of an optimal AM algorithm for systems employing packet combining, truncated ARQ and MIMO antenna configurations, considering transmission over Nakagami fading channels. Numerical results are provided for operation with or without packet combining, and show the enhanced performance and efficiency of the proposed algorithm in comparison with existing ones. © 2011 IEEE.

  19. Optical fibre sensors based on multi-mode fibres and MIMO signal processing: an experimental approach

    Science.gov (United States)

    Ahrens, Andreas; Sandmann, Andre; Bremer, Kort; Roth, Bernhard; Lochmann, Steffen

    2015-09-01

    In this paper multiple-input multiple-output (MIMO) signal processing is investigated for fibre optic sensor applications. A (2 × 2) MIMO implementation is realized by using lower-order and higher-order mode groups of a graded-index (GI) multi-mode fibre (MMF) as separate transmission channels. A micro-bending pressure sensor changes these separate transmission characteristics and introduces additional crosstalk. By observing the weight-factors of the MIMO system the amount of load applied was determined. Experiments verified a good correlation between the change of the MIMO weight coefficients and the load applied to the sensor and thus verified that MIMO signal processing can beneficially be used for fibre optic sensor applications.

  20. Vector Precoding for Gaussian MIMO Broadcast Channels: Impact of Replica Symmetry Breaking

    CERN Document Server

    Zaidel, Benjamin; Moustakas, Aris; de Miguel, Rodrigo

    2010-01-01

    The so-called "replica method" of statistical physics is employed for the large system analysis of vector precoding for the Gaussian multiple-input multiple-output (MIMO) broadcast channel. The transmitter is assumed to comprise a linear front-end combined with nonlinear precoding, that minimizes the front-end imposed transmit energy penalty. Focusing on discrete complex input alphabets, the energy penalty is minimized by relaxing the input alphabet to a larger alphabet set prior to precoding. For the common discrete-lattice relaxation, the problem is found to violate the assumption of replica symmetry and a replica symmetry breaking ansatz is taken. The limiting empirical distribution of the precoder's output, as well as the limiting energy penalty, are derived while harnessing to one-step replica symmetry breaking. Corresponding results based on the more commonly used replica symmetric ansatz are also obtained for completeness. Particularizing to a "zero-forcing" (ZF) linear front-end, and non-cooperative u...

  1. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Pal Arindam

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  2. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Arindam Pal

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for 2×2 MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  3. Channel Modelling for Multiprobe Over-the-Air MIMO Testing

    Directory of Open Access Journals (Sweden)

    Pekka Kyösti

    2012-01-01

    a fading emulator, an anechoic chamber, and multiple probes. Creation of a propagation environment inside an anechoic chamber requires unconventional radio channel modelling, namely, a specific mapping of the original models onto the probe antennas. We introduce two novel methods to generate fading emulator channel coefficients; the prefaded signals synthesis and the plane wave synthesis. To verify both methods we present a set of simulation results. We also show that the geometric description is a prerequisite for the original channel model.

  4. Performance Analysis and Comparison of Full Chip and Half Chip Rate DC and NC Code Acquisition in MIMO DSCDMA over Uncorrelated Rayleigh Wireless Channel

    OpenAIRE

    Kumar, N. Sathish; K.R. Shankar Kumar

    2011-01-01

    This paper presents the performance analysis and comparison of full chip and half chip rate of noncoherent (NC) and differentially coherent (DC) code acquisition scheme in (multiple input-multiple output) MIMO assisted by direct sequence spread spectrum (DS-CDMA) wireless system when communicated over uncorrelated Rayleigh channel. Four schemes are investigated, namely, SISO with full chip rate, SISO with Half chip rate, MIMO with full chip rate, and MIMO with half chip rate by varying the co...

  5. Particle filter for joint frequency offset and channel estimation in MIMO-OFDM systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing; LUO Han-wen; JIN Rong-hong

    2009-01-01

    A particle filter is proposed to perform joint estimation of the carrier frequency offset (CFO) and the channel in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) wireless communication systems.It marginalizes out the channel parameters from the sampling space in sequential importance sampling (SIS), and propagates them with the Kalman filter. Then the importance weights of the CFO particles are evaluated according to the imaginary part of the error between measurement and estimation. The varieties of particles are maintained by sequential importance resampling (SIR). Simulation results demonstrate this algorithm can estimate the CFO and the channel parameters with high accuracy. At the same time, some robustness is kept when the channel model has small variations.

  6. Lattice Sequential Decoder for Coded MIMO Channel: Performance and Complexity Analysis

    CERN Document Server

    Abediseid, Walid

    2011-01-01

    In this paper, the performance limit of lattice sequential decoder for lattice space-time coded MIMO channel is analysed. We determine the rates achievable by lattice coding and sequential decoding applied to such channel. The diversity-multiplexing tradeoff (DMT) under lattice sequential decoding is derived as a function of its parameter---the bias term. The bias parameter is critical for controlling the amount of computations required at the decoding stage. Achieving low decoding complexity requires increasing the value of the bias term. However, this is done at the expense of losing the optimal tradeoff of the channel. We show how such a decoder can bridge the gap between lattice decoder and low complexity decoders. Moreover, the computational complexity of lattice sequential decoder is analysed. Specifically, we derive the tail distribution of the decoder's computational complexity in the high signal-to-noise ratio regime. Similar to the conventional sequential decoder used in discrete memoryless channel,...

  7. MIMO wireless networks channels, techniques and standards for multi-antenna, multi-user and multi-cell systems

    CERN Document Server

    Clerckx, Bruno

    2013-01-01

    This book is unique in presenting channels, techniques and standards for the next generation of MIMO wireless networks. Through a unified framework, it emphasizes how propagation mechanisms impact the system performance under realistic power constraints. Combining a solid mathematical analysis with a physical and intuitive approach to space-time signal processing, the book progressively derives innovative designs for space-time coding and precoding as well as multi-user and multi-cell techniques, taking into consideration that MIMO channels are often far from ideal. Reflecting developments

  8. MIMO Multiple Access Channel with an Arbitrarily Varying Eavesdropper

    CERN Document Server

    He, Xiang; Yener, Aylin

    2012-01-01

    A two-transmitter Gaussian multiple access wiretap channel with multiple antennas at each of the nodes is investigated. The channel matrices at the legitimate terminals are fixed and revealed to all the terminals, whereas the channel matrix of the eavesdropper is arbitrarily varying and only known to the eavesdropper. The secrecy degrees of freedom (s.d.o.f.) region under a strong secrecy constraint is characterized. A transmission scheme that orthogonalizes the transmit signals of the two users at the intended receiver and uses a single-user wiretap code is shown to be sufficient to achieve the s.d.o.f. region. The converse involves establishing an upper bound on a weighted-sum-rate expression. This is accomplished by using induction, where at each step one combines the secrecy and multiple-access constraints associated with an adversary eavesdropping a carefully selected group of sub-channels.

  9. Outage and Capacity Performance Evaluation of Distributed MIMO Systems over a Composite Fading Channel

    OpenAIRE

    2014-01-01

    The exact closed-form expressions regarding the outage probability and capacity of distributed MIMO (DMIMO) systems over a composite fading channel are derived. This is achieved firstly by using a lognormal approximation to a gamma-lognormal distribution when a mobile station (MS) in the cell is in a fixed position, and the so-called maximum ratio transmission/selected combining (MRT-SC) and selected transmission/maximum ratio combining (ST-MRC) schemes are adopted in uplink and downlink, res...

  10. An analytical comparison of partial power-feedback designs for MIMO block fading channels

    OpenAIRE

    Lau, VKN

    2004-01-01

    It has been shown that with perfect feedback (CSIT), the optimal multiple input/multiple output (MIMO) transmission strategy is a cascade of channel encoder banks, power control matrix, and eigen-beamforming matrix. However, the feedback capacity requirement for perfect CSIT is 2n/sub T//spl times/n/sub R/, which is not scalable with respect to n/sub T/ or n/sub R/. In this letter, we shall compare the performance of two levels of partial power-feedback strategies, namely, the scalar symmetri...

  11. Efficient Closed-Loop Schemes for MIMO-OFDM-Based WLANs

    Directory of Open Access Journals (Sweden)

    Jiang Yi

    2006-01-01

    Full Text Available The single-input single-output (SISO orthogonal frequency-division multiplexing (OFDM systems for wireless local area networks (WLAN defined by the IEEE 802.11a standard can support data rates up to 54 Mbps. In this paper, we consider deploying two transmit and two receive antennas to increase the data rate up to 108 Mbps. Applying our recent multiple-input multiple-output (MIMO transceiver designs, that is, the geometric mean decomposition (GMD and the uniform channel decomposition (UCD schemes, we propose simple and efficient closed-loop MIMO-OFDM designs for much improved performance, compared to the standard singular value decomposition (SVD based schemes as well as the open-loop V-BLAST (vertical Bell Labs layered space-time based counterparts. In the explicit feedback mode, precoder feedback is needed for the proposed schemes. We show that the overhead of feedback can be made very moderate by using a vector quantization method. In the time-division duplex (TDD mode where the channel reciprocity is exploited, our schemes turn out to be robust against the mismatch between the uplink and downlink channels. The advantages of our schemes are demonstrated via extensive numerical examples.

  12. MIMO Channel Modeling and Capacity Analysis in Terahertz Communication%太赫兹通信中MIMO信道建模与容量分析

    Institute of Scientific and Technical Information of China (English)

    李伟琨; 姚信威; 王万良; 吴腾超

    2015-01-01

    With the development of nanotechnology and the graphene-based nano materials,terahertz communication, the preferred communication technology of nano network is becoming the new hotspot for wireless communication. However,the performance of Multiple Input Multiple Output( MIMO) channel in terahertz band is still unknown. A novel MIMO channel model in terahertz communications is proposed by using a discrete mathematical method. Combining the molecular absorption and the path loss in terahertz band,a model of channel capacity is presented based on the channel state information at the receiver. MIMO channel model in terahertz communications is verified in the simulation. Result shows that the MIMO channel in terahertz communication can support higher capacity and transmission bit-rates than the single terahertz channel.%随着纳米技术的不断发展与新型纳米材料石墨烯研究的不断深入,作为纳米网络通信技术的太赫兹通信成为无线通信的研究热点,然而现阶段对太赫兹通信中多输入多输出( MIMO)机制的研究较少。为此,采用离散化的数学方法,以接收端获取信道信息的遍历容量模型为基础,结合太赫兹信道的分子吸收噪声与传输路径损失,提出一种适用于太赫兹通信的MIMO信道模型。对建立的MIMO信道模型进行仿真与分析,结果表明,与单一太赫兹信道相比,太赫兹通信中的MIMO信道具有更高的信道容量与传输比特率。

  13. Energy-aware broadcast multiuser-MIMO precoder design with imperfect channel and battery knowledge

    OpenAIRE

    Rubio López, Javier; Pascual Iserte, Antonio

    2014-01-01

    This paper addresses the problem of resource allocation and precoder design in a multiuser MIMO broadcast system where the terminals are battery-powered devices provided with energy harvesting capabilities. Energy harvesting is a promising technology based on which it is possible to recharge the battery of the terminals using energy collected from the environment. Models for the power consumption of the front-end and decoding stages are discussed and included in the design of the proposed sch...

  14. An Investigation of Self-Interference Reduction Strategy in a Spatially Correlated MIMO Channel

    Directory of Open Access Journals (Sweden)

    Rosdiadee Nordin

    2012-01-01

    Full Text Available One of the efficient ways to transmit high data rate is by employing a multiple-input multiple-output (MIMO transmission. One of the MIMO schemes, known as spatial multiplexing (SM, relies on the linear independence data streams from different transmit antennas to exploit the capacity from the fading channels. Consequently, SM suffers from the effect of spatial correlation which is the limiting factor in achieving the capacity benefit that SM can offer. In an attempt to increase the robustness of the SM transmission in a wide range of correlated channels, the use of dynamic subcarrier allocation (DSA is investigated. The effective signal-to-interference-and-noise ratio (SINR metric is used as the performance metric to determine the subcarrier quality which can then be utilised in the allocation. Two novel variants of the subcarrier allocation scheme are proposed. It is shown that the DSA-SINR approach improves the BER performance of SM transmission in highly correlated channels environment.

  15. MIMO channel measurements using optical links on small mobile terminals

    DEFF Research Database (Denmark)

    Yanakiev, Boyan; Nielsen, Jesper Ødum; Pedersen, Gert Frølund

    2010-01-01

    presented here is specifically designed to fit in a very small volume and is optimized for low power consumption (runs on small battery), thus imitating the phone electronics. It can be used for anechoic chamber measurements, however it is designed for long range channel sounding measurements....

  16. Low-Complexity Structured Precoding for Spatially Correlated MIMO Channels

    CERN Document Server

    Raghavan, Vasanthan; Veeravalli, Venu

    2008-01-01

    The focus of this paper is on spatial precoding in correlated multi-antenna channels, where the number of independent data-streams is adapted to trade-off the data-rate with the transmitter complexity. Towards the goal of a low-complexity implementation, a structured precoder is proposed, where the precoder matrix evolves fairly slowly at a rate comparable with the statistical evolution of the channel. Here, the eigenvectors of the precoder matrix correspond to the dominant eigenvectors of the transmit covariance matrix, whereas the power allocation across the modes is fixed, known at both the ends, and is of low-complexity. A particular case of the proposed scheme (semiunitary precoding), where the spatial modes are excited with equal power, is shown to be near-optimal in matched channels. A matched channel is one where the dominant eigenvalues of the transmit covariance matrix are well-conditioned and their number equals the number of independent data-streams, and the receive covariance matrix is also well-...

  17. MIMO Communication for Cellular Networks

    CERN Document Server

    Huang, Howard; Venkatesan, Sivarama

    2012-01-01

    As the theoretical foundations of multiple-antenna techniques evolve and as these multiple-input multiple-output (MIMO) techniques become essential for providing high data rates in wireless systems, there is a growing need to understand the performance limits of MIMO in practical networks. To address this need, MIMO Communication for Cellular Networks presents a systematic description of MIMO technology classes and a framework for MIMO system design that takes into account the essential physical-layer features of practical cellular networks. In contrast to works that focus on the theoretical performance of abstract MIMO channels, MIMO Communication for Cellular Networks emphasizes the practical performance of realistic MIMO systems. A unified set of system simulation results highlights relative performance gains of different MIMO techniques and provides insights into how best to use multiple antennas in cellular networks under various conditions. MIMO Communication for Cellular Networks describes single-user,...

  18. Interference Mitigation for Cognitive Radio MIMO Systems Based on Practical Precoding

    CERN Document Server

    Chen, Zengmao; Hong, Xuemin; Thompson, John; Vorobyov, Sergiy A; Zhao, Feng; Xiao, Hailin; Ge, Xiaohu

    2011-01-01

    In this paper, we propose two subspace-projection-based precoding schemes, namely, full-projection (FP)- and partial-projection (PP)-based precoding, for a cognitive radio multiple-input multiple-output (CR-MIMO) network to mitigate its interference to a primary time-division-duplexing (TDD) system. The proposed precoding schemes are capable of estimating interference channels between CR and primary networks, and incorporating the interference from the primary to the CR system into CR precoding via a novel sensing approach. Then, the CR performance and resulting interference of the proposed precoding schemes are analyzed and evaluated. By fully projecting the CR transmission onto a null space of the interference channels, the FP-based precoding scheme can effectively avoid interfering the primary system with boosted CR throughput. While, the PP-based scheme is able to further improve the CR throughput by partially projecting its transmission onto the null space.

  19. Spatial correlation in 3D MIMO channels using fourier coefficients of power spectrums

    KAUST Repository

    Nadeem, Qurrat Ul Ain

    2015-03-01

    In this paper, an exact closed-form expression for the Spatial Correlation Function (SCF) is derived for the standardized three-dimensional (3D) multiple-input multiple-output (MIMO) channel. This novel SCF is developed for a uniform linear array of antennas with non-isotropic antenna patterns. The proposed method resorts to the spherical harmonic expansion (SHE) of plane waves and the trigonometric expansion of Legendre and associated Legendre polynomials to obtain a closed-form expression for the SCF for arbitrary angular distributions and antenna patterns. The resulting expression depends on the underlying angular distributions and antenna patterns through the Fourier Series (FS) coefficients of power azimuth and elevation spectrums. The novelty of the proposed method lies in the SCF being valid for any 3D propagation environment. Numerical results validate the proposed analytical expression and study the impact of angular spreads on the correlation. The derived SCF will help evaluate the performance of correlated 3D MIMO channels in the future. © 2015 IEEE.

  20. On the Optimality of Opportunistic Interference Alignment in 3-Transmitter MIMO Interference Channels

    CERN Document Server

    Lee, Jung Hoon; Love, David J

    2011-01-01

    In this paper, we propose opportunistic interference alignment (OIA) for three-transmitter multiple-input multiple-output (MIMO) interference channels (ICs). In the proposed OIA scheme, each transmitter has its own user group that consists of $K$ users, and each transmitter opportunistically selects the user whose received interference signals are most aligned. Thus, three-transmitter MIMO IC is opportunistically constructed by three transmitters and their selected users. Contrary to conventional IA, perfect channel information for all of the interference links is not required at the transmitter. Each user just needs to feed back one scalar value in the proposed OIA scheme. When the number of receive antennas is $N_R$ (with $N_R=2M$) and the number of transmit antennas is $N_T$ (with $N_T\\ge M$), we prove that each transmitter can achieve $M$ degrees of freedom (DoF) as the number of users in each group goes to infinity ($K\\to\\infty$), in comparison with the $\\frac{2M}{3}$ DoF known to be achievable in the th...

  1. The diversity-multiplexing tradeoff of the symmetric MIMO half-duplex relay channel

    CERN Document Server

    Karmakar, Sanjay

    2010-01-01

    The diversity-multiplexing tradeoff (DMT) is obtained for the symmetric MIMO half-duplex (HD) relay channel where the source and the destination have $n$ antennas each and the relay node has $m$ antennas (hereafter, such a channel is referred to as an $(n,m)$-relay channel). The characterization of the DMT requires the joint eigenvalue distribution of three specially correlated central Wishart random matrices, which is derived using a related result in [1], [2]. The explicit characterization of the DMT, besides providing the theoretical benchmark for evaluating performance of practical cooperative protocols on this channel, reveals several interesting facts such as: a) the HD operation of the relay fundamentally limits relay channel performance in the sense that the DMT of the full-duplex (FD) relay channel can be strictly greater than that of the HD relay channel; b) an extra antenna at the relay node on a HD relay channel does not always improve the achievable diversity order, unlike that on an FD relay cha...

  2. Diversity-Multiplexing Tradeoffs in MIMO Relay Channels

    CERN Document Server

    Gunduz, Deniz; Poor, H Vincent

    2008-01-01

    A multi-hop relay channel with multiple antenna terminals in a quasi-static slow fading environment is considered. For both full-duplex and half-duplex relays the fundamental diversity-multiplexing tradeoff (DMT) is analyzed. It is shown that, while decode-and-forward (DF) relaying achieves the optimal DMT in the full-duplex relay scenario, the dynamic decode-and-forward (DDF) protocol is needed to achieve the optimal DMT if the relay is constrained to half-duplex operation. For the latter case, static protocols are considered as well, and the corresponding achievable DMT performance is characterized.

  3. Diversity-Multiplexing Tradeoffs in MIMO Relay Channels

    OpenAIRE

    Gunduz, Deniz; Goldsmith, Andrea; Poor, H. Vincent

    2008-01-01

    A multi-hop relay channel with multiple antenna terminals in a quasi-static slow fading environment is considered. For both full-duplex and half-duplex relays the fundamental diversity-multiplexing tradeoff (DMT) is analyzed. It is shown that, while decode-and-forward (DF) relaying achieves the optimal DMT in the full-duplex relay scenario, the dynamic decode-and-forward (DDF) protocol is needed to achieve the optimal DMT if the relay is constrained to half-duplex operation. For the latter ca...

  4. Approaching the MIMO Capacity with a Low-Rate Feedback Channel in V-BLAST

    Directory of Open Access Journals (Sweden)

    Lozano Angel

    2004-01-01

    Full Text Available This paper presents an extension of the vertical Bell Laboratories Layered Space-Time (V-BLAST architecture in which the closed-loop multiple-input multiple-output (MIMO capacity can be approached with conventional scalar coding, optimum successive decoding (OSD, and independent rate assignments for each transmit antenna. This theoretical framework is used as a basis for the proposed algorithms whereby rate and power information for each transmit antenna is acquired via a low-rate feedback channel. We propose the successive quantization with power control (SQPC and successive rate and power quantization (SRPQ algorithms. In SQPC, rate quantization is performed with continuous power control. This performs better than simply quantizing the rates without power control. A more practical implementation of SQPC is SRPQ, in which both rate and power levels are quantized. The performance loss due to power quantization is insignificant when 4–5 bits are used per antenna. Both SQPC and SRPQ show an average total rate close to the closed-loop MIMO capacity if a capacity-approaching scalar code is used per antenna.

  5. Optimal Constellations for the Low SNR Noncoherent MIMO Rayleigh Fading Channel

    CERN Document Server

    Srinivasan, Shivratna Giri

    2007-01-01

    Reliable communication over the discrete input and continuous output noncoherent multiple-input multiple-output (MIMO) Rayleigh fading channel is considered when the SNR per degree of freedom is low. The input constellations are required to satisfy peak and average power constraints. When the peak-to-average power ratio of the input constellation is limited (PAPR-limited) and in the low SNR regime, the mutual information upto second order in SNR is maximized jointly over input signal matrices and their respective probabilities, over all T+1 point constellations (where T is the coherence length). Even though the problem considered is a finite dimensional non-convex optimization, it admits an elegant solution in closed form. The constellation obtained is referred to as Space Time Orthogonal Rank one Modulation (STORM), and it provides new insights into noncoherent MIMO comunications in the low SNR regime. By deriving an appropriate upper bound, it is shown that in most cases with even moderate values for PAPR a...

  6. Variational Bayes Assisted Joint Signal Detection, Noise Covariance Estimation and Channel Tracking in MIMO-OFDM Systems

    OpenAIRE

    Zhang, X.; Xiao, P.; Ma, D.; Wei, J.

    2014-01-01

    This paper introduces a robust variational bayes (Robust-VB) receiver algorithm for joint signal detection, noise covariance matrix estimation and channel impulse response (CIR) tracking in multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over time varying channels. The variational bayes (VB) framework and turbo principle are combined to accomplish the parameter estimation and data detection. In the proposed Robust-VB receiver, a modified linear ...

  7. Capacity Optimized For Multicarrier OFDM-MIMO Antenna Systems

    OpenAIRE

    Sinha, Nirmalendu Bikas; kumar, Prosenjit; Mitra, M

    2010-01-01

    Motivated by MIMO broad-band fading channel model, in this section we deals with the capacity behaviour of wireless MIMO and OFDM based spatial multiplexing systems in broad-band fading environments for the case where the channel is unknown at the transmitter and perfectly known at the receiver. This influence the propagation and system parameters on ergodic capacity, we furthermore demonstrate that, unlike the single-input single-output (SISO) case, delay spread channels may provide advantag...

  8. DFT based spatial multiplexing and maximum ratio transmission for mm-wawe large MIMO

    DEFF Research Database (Denmark)

    Phan-Huy, D.-T.; Tölli, A.; Rajatheva, N.;

    2014-01-01

    -SM-MRT). When the DFT-SM scheme alone is used, the data streams are either mapped onto different angles of departures in the case of aligned linear arrays, or mapped onto different orbital angular momentums in the case of aligned circular arrays. Maximum ratio transmission pre-equalizes the channel and......By using large point-to-point multiple input multiple output (MIMO), spatial multiplexing of a large number of data streams in wireless communications using millimeter-waves (mm-waves) can be achieved. However, according to the antenna spacing and transmitter-receiver distance, the MIMO channel is...

  9. Cross-Layer Framework for Multiuser Real Time H.264/AVC Video Encoding and Transmission over Block Fading MIMO Channels Using Outage Probability

    Directory of Open Access Journals (Sweden)

    Slavche Pejoski

    2014-01-01

    Full Text Available We present a framework for cross-layer optimized real time multiuser encoding of video using a single layer H.264/AVC and transmission over MIMO wireless channels. In the proposed cross-layer adaptation, the channel of every user is characterized by the probability density function of its channel mutual information and the performance of the H.264/AVC encoder is modeled by a rate distortion model that takes into account the channel errors. These models are used during the resource allocation of the available slots in a TDMA MIMO communication system with capacity achieving channel codes. This framework allows for adaptation to the statistics of the wireless channel and to the available resources in the system and utilization of the multiuser diversity of the transmitted video sequences. We show the effectiveness of the proposed framework for video transmission over Rayleigh MIMO block fading channels, when channel distribution information is available at the transmitter.

  10. LU based Beamforming schemes for MIMO systems

    OpenAIRE

    Mbaye, Moustapha; Diallo, Moussa; Mboup, Mamadou

    2016-01-01

    —We present a time-domain broadband beamforming based on a Unimodular-Upper polynomial matrix decomposition. The unimodular factor is the product of elementary J-orthogonal matrices and a lower triangular matrix with ones on the diagonal, as in the constant matrix LU decomposition. This leads to a J-Orthogonal LU polynomial matrix decomposition, as a combination of two classical matrix factorization methods: Smith canonical form and LU Gaussian elimination. The inversion of the unimodular fac...

  11. On Outage Probability and Diversity-Multiplexing Tradeoff in MIMO Relay Channels

    CERN Document Server

    Loyka, Sergey

    2011-01-01

    Fading MIMO relay channels are studied analytically, when the source and destination are equipped with multiple antennas and the relays have a single one. Compact closed-form expressions are obtained for the outage probability under i.i.d. and correlated Rayleigh-fading links. Low-outage approximations are derived, which reveal a number of insights, including the impact of correlation, of the number of antennas, of relay noise and of relaying protocol. The effect of correlation is shown to be negligible, unless the channel becomes almost fully correlated. The SNR loss of relay fading channels compared to the AWGN channel is quantified. The SNR-asymptotic diversity-multiplexing tradeoff (DMT) is obtained for a broad class of fading distributions, including, as special cases, Rayleigh, Rice, Nakagami, Weibull, which may be non-identical, spatially correlated and/or non-zero mean. The DMT is shown to depend not on a particular fading distribution, but rather on its polynomial behavior near zero, and is the same ...

  12. Stiefel Manifold and TCQ based on Unit Memory Coding for MIMO System

    Directory of Open Access Journals (Sweden)

    Vijey Thayananthan

    2014-02-01

    Full Text Available The Multi Input and Multi Output (MIMO systems have been analyzed with a number of quantization techniques. In this short communication, few problems like performance and accuracy are investigated through a quantization technique based on Stiefel Manifold (SM. In order to improve these problems, suitable Trellis Coded Quantization (TCQ based on Unit Memory (UM coding is studied and applied to SM of MIMO components as a novel approach. Anticipated results are the bit error performance which is an overall improvement of feedback connected between transmitter and receiver of MIMO. As a conclusion, this research not only reduces the quantization problems on SM but also improve the performance and accuracy of limited-rate feedback used in MIMO system.

  13. Artificial Neural Network trained by Genetic Algorithm for Smart MIMO Channel Estimation for Downlink LTE-Advance System

    Directory of Open Access Journals (Sweden)

    Nirmalkumar S. Reshamwala

    2014-02-01

    Full Text Available Long-Term Evolution (LTE is the next generation of current mobile telecommunication networks. LTE has a ?at radio-network architecture and signi?cant increase in spectrum efficiency, throughput and user capacity. In this paper, performance analysis of robust channel estimators for Downlink Long Term Evolution-Advanced (DL LTE-A system using three Artificial Neural Networks: Feed-forward neural network (FFNN, Cascade-forward neural network (CFNN and Layered Recurrent Neural Network (LRN are trained separately using Back-Propagation Algorithm and also ANN is trained by Genetic Algorithm (GA. The methods use the information got by the received reference symbols to estimate the total frequency response of the channel in two important phases. In the first phase, the proposed ANN based method learns to adapt to the channel variations, and in the second phase it estimates the channel matrix to improve performance of LTE. The performance of the estimation methods is evaluated by simulations in Vienna LTE-A DL Link Level Simulator in MATLAB software. Performance of the proposed channel estimator, ANN trained by Genetic Algorithm (ANN-GA is compared with traditional Least Square (LS algorithm and ANN based other estimator like Feed-forward neural network, Layered Recurrent Neural Network and Cascade-forward neural network for Closed Loop Spatial Multiplexing (CLSM-Single User Multi-input Multi-output (MIMO-2×2 and 4×4 in terms of throughput. Simulation result shows proposed ANN-GA gives better performance than other ANN based estimations methods and LS.

  14. A MAP Channel Estimation Algorithm for MIMO-OFDM Systems with Better Performance%一种性能更好的MIMO-OFDM系统MAP信道估计算法

    Institute of Scientific and Technical Information of China (English)

    许鹏; 汪晋宽; 祁峰

    2011-01-01

    Maximum a posteriori (MAP) channel estimation algorithm usually uses expectation maximum (EM) algorithm to decrease the high computation. However, this kind of operation has a difficulty in obtaining ideal estimation performance at high signal to noise ratio (SNR) because of the convergent feature of EM algorithm. In addition, for pilot-based multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) systems, data transmission efficiency of OFDM symbol will be reduced with the increasing number of transmit antennas. In order to improve these two drawbacks, firstly, an equivalent signal model is introduced to improve the convergent property of EM algorithm at high SNR. Then, to enhance the data transmission efficiency, joint estimation is implemented by making use of phase shifted orthogonal pilot sequences over multiple OFDM symbols. What's more, channel matrix is transformed between time domain and angle domain and the concept of angle domain is used to reduce the effect of noise on the estimation by using the spatial independence of MIMO channel in channel matrix of angle domain. Through performance analysis and simulation results, it is indicated that the proposed algorithm has lower estimation error and higher data transmission efficiency than the raw MAP algorithm based on EM process, which only requires increasing the computational complexity a little bit.%基于期望最大化(EM)的最大后验信道估计算法(MAP)在高信噪比(SNR)下将很难获得较低的估计误差,并且,对于导频辅助的MIMO-OFDM系统,OFDM符号的数据传输效率随着发送天线的增加而明显下降.为改善这两种缺陷,引入一种等效的信号模型来改善高SNR下的估计性能;在相邻多个OFDM符号内使用相移正交导频序列和联合估计来提高系统的数据传输效率和估计性能;根据角域内信道间的独立性来减小噪声对估计的影响.通过仿真实验可知,所提算法具有更小的

  15. Channel Models for Capacity Evaluation of MIMO Handsets in Data Mode

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Yanakiev, Boyan; Barrio, Samantha Caporal Del;

    2016-01-01

    This work investigates different correlation based models useful for evaluation of outage capacity (OC) of mobile multiple-input multiple-output (MIMO) handsets. The work is based on a large measurement campaign in a micro-cellular setup involving two dual-band base stations, 10 different handsets...... in an indoor environment for different use cases and test users. Several models are evaluated statistically, comparing the OC values estimated from the model and measurement data, respectively, for about 2,700 measurement routes. The models are based on either estimates of the full correlation...... matrices or simplifications. Among other results, it is shown that the OC can be predicted accurately (median error typically within 2.6%) with a model assuming knowledge only of the Tx-correlation coefficient and the mean power gain....

  16. Transmitter Optimization for Achieving Secrecy Capacity in Gaussian MIMO Wiretap Channels

    CERN Document Server

    Li, Jiangyuan

    2009-01-01

    We consider a Gaussian multiple-input multiple-output (MIMO) wiretap channel model, where there exists a transmitter, a legitimate receiver and an eavesdropper, each node equipped with multiple antennas. We study the problem of finding the optimal input covariance matrix that achieves secrecy capacity subject to a power constraint, which leads to a non-convex optimization problem that is in general difficult to solve. Existing results for this problem address the case in which the transmitter and the legitimate receiver have two antennas each and the eavesdropper has one antenna. For the general cases, it has been shown that the optimal input covariance matrix has low rank when the difference between the Grams of the eavesdropper and the legitimate receiver channel matrices is indefinite or semi-definite, while it may have low rank or full rank when the difference is positive definite. In this paper, the aforementioned non-convex optimization problem is investigated. In particular, for the multiple-input sing...

  17. The diversity-multiplexing tradeoff of the MIMO Z interference channel

    CERN Document Server

    Karmakar, Sanjay

    2010-01-01

    The fundamental diversity-multiplexing tradeoff (DMT) of the quasi-static fading, MIMO Z interference channel (ZIC), with $M_1$ and $M_2$ antennas at the transmitters and $N_1$ and $N_2$ antennas at the corresponding receivers, respectively, is derived. Channel state information at the transmitters (CSIT) and a short-term average power constraint is assumed. The achievability of the DMT is proved by showing that a simple Gaussian superposition coding scheme can achieve a rate region which is within a constant (independent of signal-to-noise ratio (SNR)) number of bits from an upper bound to the capacity region of the ZIC. We also characterize an achievable DMT of the ZIC with No-CSIT and show that in a small region of multiplexing gains (MG), the full CSIT DMT of the ZIC can be achieved with no CSIT at all. The size of this MG region depends on the system parameters such as the number of antennas at the four nodes (referred to hereafter as "antenna configuration"), SNRs and interference-to-noise ratio (INR) o...

  18. The diversity-multiplexing tradeoff of the symmetric MIMO 2-user interference channel

    CERN Document Server

    Karmakar, Sanjay

    2010-01-01

    The fundamental diversity-multiplexing tradeoff (DMT) of the quasi-static fading, symmetric $2$-user MIMO interference channel (IC) with channel state information at the transmitters (CSIT) and a short term average power constraint is obtained. The general case is considered where the interference-to-noise ratio (INR) at each receiver scales differently from the signal-to-noise ratio (SNR) at the receivers. The achievability of the DMT is proved by showing that a simple Han-Kobayashi coding scheme can achieve a rate region which is within a constant (independent of SNR) number of bits from a set of upper bounds to the capacity region of the IC. In general, only part of the DMT curve with CSIT can be achieved by coding schemes which do not use any CSIT (No-CSIT). A result in this paper establishes a threshold for the INR beyond which the DMT with CSIT coincides with that with No-CSIT. Our result also settles one of the conjectures made in~\\cite{EaOlCv}. Furthermore, the fundamental DMT of a class of non-symmet...

  19. Achievable rate of cognitive radio spectrum sharing MIMO channel with space alignment and interference temperature precoding

    KAUST Repository

    Sboui, Lokman

    2013-06-01

    In this paper, we investigate the spectral efficiency gain of an uplink Cognitive Radio (CR) Multi-Input MultiOutput (MIMO) system in which the Secondary/unlicensed User (SU) is allowed to share the spectrum with the Primary/licensed User (PU) using a specific precoding scheme to communicate with a common receiver. The proposed scheme exploits at the same time the free eigenmodes of the primary channel after a space alignment procedure and the interference threshold tolerated by the PU. In our work, we study the maximum achievable rate of the CR node after deriving an optimal power allocation with respect to an outage interference and an average power constraints. We, then, study a protection protocol that considers a fixed interference threshold. Applied to Rayleigh fading channels, we show, through numerical results, that our proposed scheme enhances considerably the cognitive achievable rate. For instance, in case of a perfect detection of the PU signal, after applying Successive Interference Cancellation (SIC), the CR rate remains non-zero for high Signal to Noise Ratio (SNR) which is usually impossible when we only use space alignment technique. In addition, we show that the rate gain is proportional to the allowed interference threshold by providing a fixed rate even in the high SNR range. © 2013 IEEE.

  20. Low-Complexity Full-Diversity Detection in Two-User MIMO X Channels

    KAUST Repository

    Ismail, Amr

    2014-01-26

    Several interference cancellation (IC) schemes have been recently proposed to suppress multi-user interference for various network configurations (e.g., multiple access and X channels). However, most of these schemes trade-off diversity for implementation complexity or vice-versa. In this paper, we propose a full-diversity interference cancellation scheme in a multiple-input multiple-output (MIMO) X channel with two sources and two destinations while maintaining low decoding complexity. We provide sufficient conditions for a wide range of space-time block codes (STBCs) to achieve full-diversity gain under the so-called partial interference cancellation group decoding (PICGD) in the configuration of interest. A systematic construction is then proposed to achieve full-diversity. The constructed scheme is compared to recently proposed IC scheme in terms of performance and decoding complexity. Our IC scheme outperforms the recently proposed scheme in the case it provides higher transmission rate, while it loses slightly in the case of equal rates. In terms of decoding complexity, both schemes are equivalent.

  1. On Issues about the Application of MIMO in Mobile Cellular Communications

    Institute of Scientific and Technical Information of China (English)

    REN Li-gang; SONG Mei; SONG Jun-de

    2004-01-01

    The convenience of mobile communications and the increasing demand for higher data transmitting rate have motivated people to explore more efficient methods of signal transmission because of the limited spectral resource. Multiple-Input and Multiple-Output (MIMO) is a high spectral efficient method and the theoretical capacity of a MIMO channel increases linearly with the number of transmitting/receiving antennas under the ideal conditions. We can adopt MIMO technology in the new generation of mobile cellular communication systems, which is IP based and requires high data rate to support multimedia services. Although much progress has been made in MIMO area recently, there are some problems in its practical application, especially in cellular application. In this paper we will analyze the channel model, the capacity and the technology of MIMO, and then we will focus on the issues of MIMO application in mobile cellular system by the Monte Carlo simulation and give the available solution schemes for the issues.

  2. Leakage based precoding for multi-user MIMO-OFDM systems

    KAUST Repository

    Sadek, Mirette

    2011-08-01

    In downlink multi-user multiple-input multiple-output (MIMO) transmissions, several precoding schemes have been proposed to decrease interference among users. Notable among these precoding schemes is one that uses the signal-to-leakage-plus-noise ratio (SLNR) as an optimization criterion. In this paper, leveraging the efficiency of the SLNR optimization, we generalize this precoding scheme to MIMO orthogonal frequency division multiplexing (OFDM) multi-user systems where the OFDM is used to overcome the inter-symbol- interference (ISI) introduced by multipath channels. We also introduce a channel compensation technique that reconstructs the channel at the transmitter for every time instant given a significantly lower channel feedback rate by the receiver. © 2006 IEEE.

  3. Improving Performance of Wi-Fi by Compact MIMO Systems by using Gama Frequency-Selective Fading Channels

    Directory of Open Access Journals (Sweden)

    Mr. Sudesh Gupta

    2011-09-01

    Full Text Available In this paper we propose a compact MIMO system in frequency-selective fading channels which improves the performance of Wireless Media. A MIMO beam forming system model with mutual coupling and matching network is proposed to cope with frequency-selective fading channels. The overall system proposed transfer matrix is derived using Z-parameter method. The system using the transform matrix which accepts the relay and the delay matrix for the computation. Then apply the diversity criteria by which we can make the code output pair which is distinct. So we can obtain two different pairs one is shows the below value in the MIMO System one is the Higher value. It is the only way to achieve orthogonally. One particular problem with this is that it has uneven power among the symbols it transmits. This means that the signal does not have a constant envelope and that the power each antenna must transmit has to vary, both of which are undesirable. We can take the middle value which overcomes this problem.

  4. Improving Performance of Wi-Fi by Compact MIMO Systems by using Gama Frequency-Selective Fading Channels

    Directory of Open Access Journals (Sweden)

    Sudesh Gupta

    2011-12-01

    Full Text Available In this paper we propose a compact MIMO system in frequency-selective fading channels which improves the performance of Wireless Media. A MIMO beam forming system model with mutual coupling and matching network is proposed to cope with frequency-selective fading channels. The overall system proposed transfer matrix is derived using Z-parameter method. The system using the transform matrix which accepts the relay and the delay matrix for the computation. Then apply the diversity criteria by which we can make the code output pair which is distinct. So we can obtain two different pairs one is shows the below value in the MIMO System one is the Higher value. It is the only way to achieve orthogonally. One particular problem with this is that it has uneven power among the symbols it transmits. This means that the signal does not have a constant envelope and that the power each antenna must transmit has to vary, both of which are undesirable. We can take the middle value which overcomes this problem.

  5. On Low-Complexity Full-diversity Detection In Multi-User MIMO Multiple-Access Channels

    KAUST Repository

    Ismail, Amr

    2014-01-28

    Multiple-input multiple-output (MIMO) techniques are becoming commonplace in recent wireless communication standards. This newly introduced dimension (i.e., space) can be efficiently used to mitigate the interference in the multi-user MIMO context. In this paper, we focus on the uplink of a MIMO multiple access channel (MAC) where perfect channel state information (CSI) is only available at the destination. We provide new sufficient conditions for a wide range of space-time block codes (STBC)s to achieve full-diversity under partial interference cancellation group decoding (PICGD) with or without successive interference cancellation (SIC) for completely blind users. Interference cancellation (IC) schemes for two and three users are then provided and shown to satisfy the full-diversity criteria. Beside the complexity reduction due to the fact that PICGD enables separate decoding of distinct users without sacrificing the diversity gain, further reduction of the decoding complexity may be obtained. In fact, thanks to the structure of the proposed schemes, the real and imaginary parts of each user\\'s symbols may be decoupled without any loss of performance. Our new IC scheme is shown to outperform recently proposed two-user IC scheme especially for high spectral efficiency while requiring significantly less decoding complexity.

  6. A MIMO-OFDM Testbed, Channel Measurements, and System Considerations for Outdoor-Indoor WiMAX

    Directory of Open Access Journals (Sweden)

    Víctor P. Gil Jiménez

    2010-01-01

    Full Text Available The design, implementation, and test of a real-time flexible 2×2 (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing MIMO-OFDM IEEE 802.16 prototype are presented. For the design, a channel measurement campaign on the 3.5 GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter CDIT capacity is close to (Channel State Information at the Transmitter CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements.

  7. A MIMO-OFDM Testbed, Channel Measurements, and System Considerations for Outdoor-Indoor WiMAX

    Directory of Open Access Journals (Sweden)

    Torres

    2010-01-01

    Full Text Available The design, implementation, and test of a real-time flexible (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing MIMO-OFDM IEEE 802.16 prototype are presented. For the design, a channel measurement campaign on the 3.5 GHz band has been carried out, focusing on outdoor-indoor scenarios. The analysis of measured channels showed that higher capacity can be achieved in case of obstructed scenarios and that (Channel Distribution Information at the Transmitter CDIT capacity is close to (Channel State Information at the Transmitter CSIT with much lower complexity and requirements in terms of channel estimation and feedback. The baseband prototype used an (Field Programmable Gate Array FPGA where enhanced signal processing algorithms are implemented in order to improve system performance. We have shown that for MIMO-OFDM systems, extra signal processing such as enhanced joint channel and frequency offset estimation is needed to obtain a good performance and approach in practice the theoretical capacity improvements.

  8. Diversity-Based Geometry Optimization in MIMO Passive Coherent Location

    Directory of Open Access Journals (Sweden)

    M. Radmard

    2014-04-01

    Full Text Available Applying the recently emerged technique‎, ‎MIMO (Multiple Input Multiple Output to PCL (Passive Coherent‎ ‎Location is expected to improve performance of localization schemes‎. ‎In this paper‎, ‎we explore the‎ ‎application of MIMO technology to PCL schemes and see how it improves the spatial diversity of such systems‎. ‎Specifically‎, ‎we use the DVB-T stations as the‎ ‎illuminators of opportunity in the simulations‎, ‎mainly because of their unique features which‎ ‎make them quite suitable for both MIMO and PCL application as will be demonstrated in this‎ ‎paper‎. ‎In addition‎, ‎we address the key problem of finding optimum locations for placement of receive antennas‎.

  9. On the Pareto Boundary for the Two-User Single-Beam MIMO Interference Channel

    CERN Document Server

    Cao, Pan; Shi, Shuying

    2012-01-01

    We consider a two-user multiple-input multiple-output (MIMO) interference channel (IC), where a single data stream is transmitted and each receiver applies the minimum mean square error (MMSE) filter. In this paper, we study an open topic on the Pareto boundary of the rate region. The Pareto boundary is divided by two turning points into the weak Pareto boundary (including the horizontal part and vertical part) and the strict Pareto boundary (including the upper-right part and turning points). The weak Pareto boundary and turning points can be computed exactly. For the strict Pareto boundary, we propose a computationally efficient method called iterative alternating algorithm (IAA) for maximizing the rate of one user while the rate of the other user is fixed. To deal with the difficult coupling of the two transmit beamformers in this optimization problem, we convert it into two single-beamformer optimization problems. Then, by certain equivalent transformations, each problem becomes a quadratically constraine...

  10. ISI Cancellation Using Blind Equalizer Based on DBC Model for MIMO-RFID Reader Reception

    Directory of Open Access Journals (Sweden)

    S. Duangsuwan

    2015-04-01

    Full Text Available Under the dyadic backscatter channel (DBC model, a conventional zero forcing (ZF and minimum mean square error (MMSE method for MIMO-RFID reader reception are not able to be rapidly cancelled inter-symbol interference (ISI because of the error of postpreamble transmission. In order to achieve the ISI cancellation, the conventional method of ZF and MMSE are proposed to resolve a convergence rate without postpreamble by using a constant modulus algorithm (CMA. Depending on the cost function, the CMA is used which based on second order statistics to estimate the channel statement of channel transfer function. Furthermore, the multiple-tag detection is also considered under the assumption of the maximum likelihood estimation. The comparison of the conventional method and the proposed method is analyzed by using computer simulation and experimental data. We can see that the proposed method is better than the conventional method with a faster ISI cancelling and a lower bit error rate (BER improving as up to 12 tags.

  11. Performance of RCPC-Encoded V-BLAST MIMO In Nakagami-m Fading Channel

    OpenAIRE

    Sari, L.; Wibisono, G.; Gunawan, D.

    2010-01-01

    Multiple Input Multiple Output (MIMO) wireless communication link has been theoretically proven to be reliable and capable of achieving high capacity. However, these two advantageous characteristics tend to be addressed separately in many major researches. Researches on various approaches to attain both characteristics in a single MIMO system are still on-going and an established approach is yet to be concluded. To address this problem, in this paper a Vertical Bell Laboratories Layered Space...

  12. A Variational Approach to the Modeling of MIMO Systems

    Directory of Open Access Journals (Sweden)

    Jraifi A

    2007-01-01

    Full Text Available Motivated by the study of the optimization of the quality of service for multiple input multiple output (MIMO systems in 3G (third generation, we develop a method for modeling MIMO channel . This method, which uses a statistical approach, is based on a variational form of the usual channel equation. The proposed equation is given by with scalar variable . Minimum distance of received vectors is used as the random variable to model MIMO channel. This variable is of crucial importance for the performance of the transmission system as it captures the degree of interference between neighbors vectors. Then, we use this approach to compute numerically the total probability of errors with respect to signal-to-noise ratio (SNR and then predict the numbers of antennas. By fixing SNR variable to a specific value, we extract informations on the optimal numbers of MIMO antennas.

  13. Research on Helicopter-borne MIMO Microwave Imaging Technology Based on Arc Antenna Array

    Directory of Open Access Journals (Sweden)

    Huang Ping-ping

    2015-02-01

    Full Text Available This study proposes a novel Multiple Input Multiple Output (MIMO microwave imaging mode based on arc antenna array, which is mounted on the belly of platform. In this mode, an arc aperture is quickly synthesized using an MIMO. Consequently, high space and time resolution images of the illuminated scene around the platform are acquired. First, an imaging principle model based on arc antenna array is described, and its signal model is developed. Then, an imaging algorithm based on confocal projection is discussed and the performance of the mode is analyzed. Finally, the feasibility of the imaging mode and the validity of the proposed algorithm are demonstrated with a numerical simulation.

  14. Grayscale Image Transmission over Rayleigh Fading Channel in a MIMO System Using Different Digital Modulation Techniques with STBC

    Directory of Open Access Journals (Sweden)

    Animish S. Andraskar

    2015-04-01

    Full Text Available The consistent demand for higher data rates and ability to send large volumes of data without compromising the quality of communication has led the development of a new generations of wireless systems. But range and data rate limitations are there in wireless devices. In an effort to overcome these limitations, Multi Input Multi Output (MIMO systems can be used which also increase diversity and improve the bit error rate (BER performance of wireless systems. They also increase the channel capacity, increase the transmitted data rate through spatial multiplexing, and/or reduce interference from other users. MIMO systems thus make a promising communication systems because of their high transmission rates without additional bandwidth or transmit power and robustness against multipath fading. This paper focuses on transmission of an image file using 2x2 MIMO system that achieves a full diversity gain using Alamouti’s Space Time Block Coding technique for 2 transmitting antennas and 2 receiving antennas. Different modulation techniques viz. BPSK, QPSK, 16-QAM and 64-QAM are used and performances has been evaluated in terms of BER vs. SNR to find out the best modulation technique in a given environment. Space-Time Codes have been used which in addition to the time and spectral domain, also exploit the spatial domain. Simple maximum likelihood decoding algorithm is used at the receiver side to decode the received encoded signal.

  15. Novel Base Station MIMO Antennas with Enhanced Spectral Efficiencies Using Angular Reuse

    Directory of Open Access Journals (Sweden)

    Miguel Mora-Andreu

    2015-01-01

    Full Text Available The true polarization diversity (TPD technique is combined with the spatial diversity technique in novel MIMO antenna array geometries with a large number of elements. The use of a large number of elements requires some angular reuse within the array for polarization diversity. With designs compatible with existing base station antenna array configurations, the novel geometries with combining diversity schemes are shown to be able to achieve near the maximum spectral efficiencies. True polarization diversity (TPD schemes are found to be an excellent complement to more conventional spatial diversity schemes for obtaining optimum MIMO array performance in base station antennas.

  16. A novel differential multiuser detection algorithm for multiuser MIMO-OFDM systems

    Institute of Scientific and Technical Information of China (English)

    Zheng-min KONG; Guang-xi ZHU; Qiao-ling TONG; Yan-chun LI

    2010-01-01

    We propose an efficient low bit error rate(BER)and low complexity multiple-input multiple-output(MIMO)multiuser detection(MUD)method for use with multiuser MIMO orthogonal frequency division multiplexing(OFDM)systems.It is a hybrid method combining a multiuser-interference-cancellation-based decision feedback equalizer using error feedback filter(MIMO MIC DFE-EFF)and a differential algorithm.The proposed method,termed 'MIMO MIC DFE-EFF with a differential algorithm' for short,has a multiuser feedback structure.We describe the schemes of MIMO MIC DFE-EFF and MIMO MIC DFE-EFF with a differential algorithm,and compare their minimum mean square error(MMSE)performance and computational complexity.Simulation results show that a significant performance gain can be achieved by employing the MIMO MIC DFE-EFF detection algorithm in the context of a multiuser MIMO-OFDM system over frequency selective Rayleigh channel.MIMO MIC DFE-EFF with the differential algorithm improves both computational efficiency and BEg performance in a multistage structure relative to conventional DFE-EFF,though there is a small reduction in system performance compared with MIMO MIC DFE-EFF without the differential algorithm.

  17. Multi-User Diversity vs. Accurate Channel State Information in MIMO Downlink Channels

    OpenAIRE

    Ravindran, Niranjay; Jindal, Nihar

    2009-01-01

    In a multiple transmit antenna, single antenna per receiver downlink channel with limited channel state feedback, we consider the following question: given a constraint on the total system-wide feedback load, is it preferable to get low-rate/coarse channel feedback from a large number of receivers or high-rate/high-quality feedback from a smaller number of receivers? Acquiring feedback from many receivers allows multi-user diversity to be exploited, while high-rate feedback allows for very pr...

  18. Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System

    OpenAIRE

    Wei Wang,; Dong Liang; Zhihua Wang, Haiyang Yu, Qi Liu

    2015-01-01

    The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO) imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS) and phase locked loop (PLL). A signal conditioning circuit is used to deal with the coupl...

  19. Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System

    OpenAIRE

    Wei Wang,; Dong Liang; Zhihua Wang; Haiyang Yu; Qi Liu

    2015-01-01

    The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO) imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS) and phase locked loop (PLL). A signal conditioning circuit is used to deal with the coup...

  20. Multi-User Diversity vs. Accurate Channel State Information in MIMO Downlink Channels

    CERN Document Server

    Ravindran, Niranjay

    2009-01-01

    In a multiple transmit antenna, single antenna per receiver downlink channel with limited channel state feedback, we consider the following question: given a constraint on the total system-wide feedback load, is it preferable to get low-rate/coarse channel feedback from a large number of receivers or high-rate/high-quality feedback from a smaller number of receivers? Acquiring feedback from many receivers allows multi-user diversity to be exploited, while high-rate feedback allows for very precise selection of beamforming directions. We show that there is a strong preference for obtaining high-quality feedback, and that obtaining near-perfect channel information from as many receivers as possible provides a significantly larger sum rate than collecting a few feedback bits from a large number of users.

  1. 互耦效应对双散射MIMO系统信道容量影响研究%Effect of mutual coupling on channel capacity of double-scattering MIMO systems

    Institute of Scientific and Technical Information of China (English)

    李岳衡; 燕璐; 彭文杰; 谭国平

    2013-01-01

    Multiple input multiple output (MIMO) is one of the key technologies for the fourth generation mobile communication systems, while the mutual coupling (MC) effect among antenna arrays especially under small-size interval is an important factor which may affect the performance of MIMO systems. In this paper we first study a double-scattering MIMO channel transmission model which is more suitable for simulating actual radio transmission environment; Then we introduce MC effect into the double-scattering MIMO transmission systems; Next, based on the establishment of the equivalent coupling model of multi-antenna system, the math expressions of spatial correlation and channel capacity are deduced; Finally, the MC effect on MIMO channel capacity is analyzed numerically in the double-scattering situation through computer simulations. The result of simulations shows that the MC effect will reduce the channel capacity in the double-scattering situation.%多入多出(MIMO)传输技术是第四代移动通信系统的关键技术之一,而小尺寸间隔下天线阵元间的互耦效应则是有可能影响MIMO系统性能的一个重要因素.文中首先研究分析了一种接近实际电波传输环境的、收发端皆存在散射体的双散射MIMO信道传输模型,然后将天线互耦效应引入此MIMO传输系统;接下来通过建立多天线系统等效互耦效应网络模型,推导了互耦效应影响下空间相关系数和信道容量表达式;最后通过计算机仿真研究了双散射环境下天线阵元互耦对MIMO系统信道容量的影响.仿真实验表明:双散射环境下,互耦效应将降低MIMO系统信道容量.

  2. Measurement Verification of Plane Wave Synthesis Technique Based on Multi-probe MIMO-OTA Setup

    DEFF Research Database (Denmark)

    Fan, Wei; Carreño, Xavier; Nielsen, Jesper Ødum; Olesen, Kim; Knudsen, Mikael; Pedersen, Gert Frølund

    Standardization work for MIMO OTA testing methods is currently ongoing, where a multi-probe anechoic chamber based solution is an important candidate. In this paper, the probes located on an OTA ring are used to synthesize a plane wave field in the center of the OTA ring. This paper investigates ...

  3. Investigating the Impact of Hybrid/SPREAD MIMO-OFDM System for Spectral-Efficient Wireless Networks

    Directory of Open Access Journals (Sweden)

    Nirmalendu Bikas Sinha

    2010-05-01

    Full Text Available This research proposes a novel signal scheme called Hybrid spread MIMO-OFDM system which interface OFDM with CDMA and integrate this CDMA-OFDM to MIMO to generate a system functionally superior to MIMO-OFDM systems are considered as candidates for future broadband wireless service. OFDM may be combined with antenna arrays at the transmitter and receiver to increase the diversity gain and/or to enhance the system capacity on time-variant and frequency-selective channels, resulting in a Multiple-Input Multiple-Output (MIMO configuration. The multiplexing technique proposed here is the Code Division Multiple Accesses (CDMA scheme which is considered the solution for eliminating the distortion caused by fast fading and provides the inherent advantage of DS-CDMA systems incorporating a spreading signal based on PN code sequence, by providing user discrimination based on coding at the same carrier frequency and simultaneously. The OFDM component provides resistance to multipath effects making it unnecessary to use RAKE receivers for CDMA and thus avoid hardware complexity. In order to compare their performances, the effects of multipath signal propagation on the capacity, under both single and multi user channel, are examined. The Inter Symbol Interference (ISI is used as a suitable measure of multipath effect. The obtained results show that the multipath has more influence on the capacity of MIMO than MIMO-OFDM and spread MIMO-OFDM. In addition, spread MIMO-OFDM offers more average capacity than MIMO under both single and multi user channel. In comparison with MIMO-OFDM, the capacity of spread MIMO-OFDM is higher under the condition of the multi user channel scenario. MIMO-OFDM spread system is being implemented using AWG and VSA. Thus making it possible to implement 4G using hardware and MATLAB/SIMULINK.

  4. Hybrid Genetic Crossover Based Swarm Intelligence Optimization for Efficient Resource Allocation in MIMO OFDM Systems

    Directory of Open Access Journals (Sweden)

    B. Sathish Kumar

    2015-07-01

    Full Text Available Rapid development of wireless services, leads to ubiquitous personal connectivity in the world. The demand for multimedia interactivity is higher in the world which leads to the requirement of high data transmission rate. Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM is a future wireless service which is used to overcome the existing service problems such as development of subscriber pool and higher throughput per user. Although it overcomes the problems in existing services, resource allocation becomes one of the major issues in the MIMO-OFDM systems. Resource allocation in MIMO-OFDM is the optimization of subcarrier and power allocation for the user. The overall performance of the system can be improved only with the efficient resource allocation approach. The user data rate is increased by efficient allocation of the subcarrier and power allocation for each user at the base station, which is subject to constraints on total power and bit error rate. In this study, the problem of resource allocation in MIMO-OFDM system is tackled using hybrid artificial bee colony optimization algorithm based on a crossover operation along with Poisson-Jensen in equation. The experimental results show that the proposed methodology is better than the existing techniques.

  5. Multiuser MIMO Channel Measurements and Performance in a Large Office Environment

    DEFF Research Database (Denmark)

    Bauch, Gerhard; Andersen, Jørgen Bach; Guthy, Christian; Herdin, Markus; Nielsen, Jesper Ødum; Nossek, Josef A; Tejera, Pedro; Utschick, Wolfgang

    surface and material. We show results on the achievable multiuser MIMO data rates for the given scenario, compare to theoretical limits and discuss the results in the light of the insights gained from the measurement campaign. We also introduce restrictions on the rate distribution between users, i.e. Qo...

  6. MIMO channel capacity versus mutual coupling in multi antenna element system

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne

    2004-01-01

    capacity, configurations with the lowest envelope correlations are not necessarily the most suitable for a MIMO system. A certain bandwidth is required as well. Three planar inverted F-antennas (PIFA) located on the same 40 mm x 100 mm ground plane. The antennas that haves a resonant frequency of 1.8 GHz...

  7. MIMO Detection Algorithms for High Data Rate Wireless Transmission

    CERN Document Server

    Sinha, Nirmalendu Bikas; Mitra, M

    2010-01-01

    Motivated by MIMO broad-band fading channel model, in this section a comparative study is presented regarding various uncoded adaptive and non-adaptive MIMO detection algorithms with respect to BER/PER performance, and hardware complexity. All the simulations are conducted within MIMO-OFDM framework and with a packet structure similar to that of IEEE 802.11a/g standard. As the comparison results show, the RLS algorithm appears to be an affordable solution for wideband MIMO system targeting at Giga-bit wireless transmission. So MIMO can overcome huge processing power required for MIMO detection by using optimizing channel coding and MIMO detection.

  8. BLIND EQUALIZATION OF MIMO SYSTEMS BASED ON ORTHOGONAL CONSTANT MODULUS ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper investigates adaptive blind source separation and equalization for Multiple Input Mul-tiple Output (MIMO) systems. To effectively recover input signals, remove Inter-Symbol Interference (ISI)and suppress Inter-User Interference (IUI), the array input is first transformed into the signal subspace, thenwith the derived orthogonality between weight vectors of different input signals, a new orthogonal ConstantModulus Algorithm (CMA) is proposed. Computer simulation results illustrate the promising performance ofthe proposed method. Without channel identification, the proposed method can recover all the system inputssimultaneously and can be adaptive to channel changes without prior knowledge about signals.

  9. Design of Transmitter for CDM Based 2×2 Multiple Input Multiple Output Channel Sounder for Multipath Delay Measurement

    Directory of Open Access Journals (Sweden)

    M. H. Ullah

    2012-01-01

    Full Text Available Problem statement: Multiple Input Multiple Output (MIMO wireless communication system is an innovative solution to improve the bandwidth efficiency by exploiting multipath-richness of the propagation environment. The degree of multipath-richness of the channel will determine the capacity gain attainable by MIMO deployment. Approach: Therefore, it is very important to have accurate knowledge of the propagation environment/radio channel before MIMO implement. The radio channel behavior can be anticipated by channel measurement or channel sounding. Code Division Multiplexing (CDM is one of the channel sounding techniques that allow accurate measurement at the cost of hardware complexity. CDM based channel sounder, requires code with excellent auto-correlation and cross-correlation properties which generally difficult to be achieved simultaneously. Results: In this study, an efficient transmitter for CDM-based 2×2 MIMO channel sounding technique with Loosely Synchronous (LS codes is designed. Simulation results shows that the channel sounding scheme using LS codes gives very good performance for measuring 2×2 MIMO channel behavior. The BPSK transmitter is designed using MATLAB, Verilog and Xilinx system generator blocks. Conclusion: The whole design is simulated as a single ISE project by using ModelSim simulation tool and compiled using ISE 9.2. However the proposed design of transmitter using LS code of length 8190 bits can measure multipath delay of minimum 0.13 μs and maximum 520 μs.

  10. How to Achieve the Optimal DMT of Selective Fading MIMO Channels?

    OpenAIRE

    Mroueh, Lina; Belfiore, Jean-Claude

    2010-01-01

    In this paper, we consider a particular class of selective fading channel corresponding to a channel that is selective either in time or in frequency. For this class of channel, we propose a systematic way to achieve the optimal DMT derived in Coronel and B\\"olcskei, IEEE ISIT, 2007 by extending the non-vanishing determinant (NVD) criterion to the selective channel case. A new code construction based on split NVD parallel codes is then proposed to satisfy the NVD parallel criterion. This resu...

  11. SAGE信道估计算法在部分相关STTC-MIMO系统中的应用%SAGE-Based Channel Estimation Algorithm Applied in Partially Correlated STTC-MIMO System

    Institute of Scientific and Technical Information of China (English)

    茹国宝; 许春晖; 李鹏飞

    2008-01-01

    利用天线空间相关函数和方向特性将完全不相关的信道衰落矩阵映射为更符合实际的部分相关MIMO(multiple input multiple output)信道衰落矩阵,结合STTC(space-time trellis code)空时编码方式建立部分相关的STTC-MIMO系统,并将基于SAGE(space-alternating generalized expectation-maximization)的信道估计算法应用在这一系统中.结果显示,和ML(most-likelihood)估计相比,部分相关信道中使用SAGE估计算法可以使系统信噪比提高约1 dB.此外,空时编码(space-time codes)的纠错性能对MIMO系统的信噪比也有极大的影响.

  12. On the MIMO channel capacity saturation for spatially constrained receive region

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In MIMO wireless communication systems,when more and more antennas are packed into spatiallylimited receive region,the antenna saturation phenomenon will appear.Moreover,the electromagnetic interactions among antennas will also become stronger and stronger and affect the antenna saturation effect considerably.Despite this,few studies consider these two effects jointly.The effects of antenna saturation are investigated under the consideration of mutual coupling,thus a more practical and physically meaningful result can be obtained.

  13. How to Achieve the Optimal DMT of Selective Fading MIMO Channels?

    CERN Document Server

    Mroueh, Lina

    2010-01-01

    In this paper, we consider a particular class of selective fading channel corresponding to a channel that is selective either in time or in frequency. For this class of channel, we propose a systematic way to achieve the optimal DMT derived in Coronel and B\\"olcskei, IEEE ISIT, 2007 by extending the non-vanishing determinant (NVD) criterion to the selective channel case. A new code construction based on split NVD parallel codes is then proposed to satisfy the NVD parallel criterion. This result is of significant interest not only in its own right, but also because it settles a long-standing debate in the literature related to the optimal DMT of selective fading channels.

  14. Interference Alignment-based Precoding and User Selection with Limited Feedback in Two-cell Downlink Multi-user MIMO Systems

    Directory of Open Access Journals (Sweden)

    Yin Zhu

    2016-05-01

    Full Text Available Interference alignment (IA is a new approach to address interference in modern multiple-input multiple-out (MIMO cellular networks in which interference is an important factor that limits the system throughput. System throughput in most IA implementation schemes is significantly improved only with perfect channel state information and in a high signal-to-noise ratio (SNR region. Designing a simple IA scheme for the system with limited feedback and investigating system performance at a low-to-medium SNR region is important and practical. This paper proposed a precoding and user selection scheme based on partial interference alignment in two-cell downlink multi-user MIMO systems under limited feedback. This scheme aligned inter-cell interference to a predefined direction by designing user’s receive antenna combining vectors. A modified singular value decomposition (SVD-based beamforming method and a corresponding user-selection algorithm were proposed for the system with low rate limited feedback to improve sum rate performance. Simulation results show that the proposed scheme achieves a higher sum rate than traditional schemes without IA. The modified SVD-based beamforming scheme is also superior to the traditional zero-forcing beamforming scheme in low-rate limited feedback systems. The proposed partial IA scheme does not need to collaborate between transmitters and joint design between the transmitter and the users. The scheme can be implemented with low feedback overhead in current MIMO cellular networks.

  15. Closed form fourier-based transmit beamforming for MIMO radar

    KAUST Repository

    Lipor, John J.

    2014-05-01

    In multiple-input multiple-output (MIMO) radar setting, it is often desirable to design correlated waveforms such that power is transmitted only to a given set of locations, a process known as beampattern design. To design desired beam-pattern, current research uses iterative algorithms, first to synthesize the waveform covariance matrix, R, then to design the actual waveforms to realize R. In contrast to this, we present a closed form method to design R that exploits discrete Fourier transform and Toeplitz matrix. The resulting covariance matrix fulfills the practical constraints and performance is similar to that of iterative methods. Next, we present a radar architecture for the desired beampattern that does not require the synthesis of covariance matrix nor the design of correlated waveforms. © 2014 IEEE.

  16. Finite time control for MIMO nonlinear system based on higher-order sliding mode.

    Science.gov (United States)

    Liu, Xiangjie; Han, Yaozhen

    2014-11-01

    Considering a class of MIMO uncertain nonlinear system, a novel finite time stable control algorithm is proposed based on higher-order sliding mode concept. The higher-order sliding mode control problem of MIMO nonlinear system is firstly transformed into finite time stability problem of multivariable system. Then continuous control law, which can guarantee finite time stabilization of nominal integral chain system, is employed. The second-order sliding mode is used to overcome the system uncertainties. High frequency chattering phenomenon of sliding mode is greatly weakened, and the arbitrarily fast convergence is reached. The finite time stability is proved based on the quadratic form Lyapunov function. Examples concerning the triple integral chain system with uncertainty and the hovercraft trajectory tracking are simulated respectively to verify the effectiveness and the robustness of the proposed algorithm. PMID:25277626

  17. Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2015-06-01

    Full Text Available The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS and phase locked loop (PLL. A signal conditioning circuit is used to deal with the coupling effect within the array. The signal processing platform is based on an efficient field programmable gates array (FPGA and digital signal processor (DSP pipeline where a robust beamforming imaging algorithm is running on. The radar system was evaluated through a real field experiment. Imaging capability and real-time performance shown in the results demonstrate the practical feasibility of the implementation.

  18. On the performance of diagonal lattice space-time codes for the quasi-static MIMO channel

    KAUST Repository

    Abediseid, Walid

    2013-06-01

    There has been tremendous work done on designing space-time codes for the quasi-static multiple-input multiple-output (MIMO) channel. All the coding design to date focuses on either high-performance, high rates, low complexity encoding and decoding, or targeting a combination of these criteria. In this paper, we analyze in detail the performance of diagonal lattice space-time codes under lattice decoding. We present both upper and lower bounds on the average error probability. We derive a new closed form expression of the lower bound using the so-called sphere-packing bound. This bound presents the ultimate performance limit a diagonal lattice space-time code can achieve at any signal-to-noise ratio (SNR). The upper bound is simply derived using the union-bound and demonstrates how the average error probability can be minimized by maximizing the minimum product distance of the code. © 2013 IEEE.

  19. A cross-layer resource allocation scheme for spatial multiplexing-based MIMO-OFDMA systems

    OpenAIRE

    Al-Shatri Hussein; Akbudak Tarik; Czylwik Andreas

    2011-01-01

    Abstract We investigate the resource allocation problem for the downlink of a multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) system. The sum rate maximization itself cannot cope with fairness among users. Hence, we address this problem in the context of the utility-based resource allocation presented in earlier papers. This resource allocation method allows to enhance the efficiency and guarantee fairness among users by exploiting multiuser diversity...

  20. MIMO Detection for High-Order QAM Based on a Gaussian Tree Approximation

    OpenAIRE

    Goldberger, Jacobb; Leshem, Amir

    2010-01-01

    This paper proposes a new detection algorithm for MIMO communication systems employing high order QAM constellations. The factor graph that corresponds to this problem is very loopy; in fact, it is a complete graph. Hence, a straightforward application of the Belief Propagation (BP) algorithm yields very poor results. Our algorithm is based on an optimal tree approximation of the Gaussian density of the unconstrained linear system. The finite-set constraint is then applied to obtain a loop-fr...

  1. On Secrecy Rate Analysis of MIMO Wiretap Channels Driven by Finite-Alphabet Input

    CERN Document Server

    Bashar, Shafi; Xiao, Chengshan

    2011-01-01

    This work investigates the effect of finite-alphabet source input on the secrecy rate of a multi-antenna wiretap system. Existing works have characterized maximum achievable secrecy rate or secrecy capacity for single and multiple antenna systems based on Gaussian source signals and secrecy code. Despite the impracticality of Gaussian sources, the compact closed-form expression of mutual information between linear channel Gaussian input and corresponding output has led to broad application of Gaussian input assumption in physical secrecy analysis. For practical considerations, we study the effect of finite discrete-constellation on the achievable secrecy rate of multiple-antenna wire-tap channels. Our proposed precoding scheme converts the multi-antenna system into a bank of parallel channels. Based on this precoding strategy, we propose a decentralized power allocation algorithm based on dual decomposition for maximizing the achievable secrecy rate. In addition, we analyze the achievable secrecy rate for fin...

  2. A capon beamforming method for clutter suppression in colocated compressive sensing based MIMO radars

    Science.gov (United States)

    Yu, Yao; Sun, Shunqiao; Petropulu, Athina P.

    2013-05-01

    Compressive sensing (CS) based multi-input multi-output (MIMO) radar systems that explore the sparsity of targets in the target space enable either the same localization performance as traditional methods but with significantly fewer measurements, or significantly improved performance with the same number of measurements. However, the enabling assumption, i.e., the target sparsity, diminishes in the presence of clutter, since clutters is highly correlated with the desire target echoes. This paper proposes an approach to suppress clutter in the context of CS MIMO radars. Assuming that the clutter covariance is known, Capon beamforming is applied at the fusion center on compressively obtained data, which are forwarded by the receive antennas. Subsequently, the target is estimated using CS theory, by exploiting the sparsity of the beamformed signals.

  3. DOA estimation for monostatic MIMO radar based on unitary root-MUSIC

    Science.gov (United States)

    Wang, Wei; Wang, Xianpeng; Li, Xin; Song, Hongru

    2013-11-01

    Direction of arrival (DOA) estimation is an important issue for monostatic MIMO radar. A DOA estimation method for monostatic MIMO radar based on unitary root-MUSIC is presented in this article. In the presented method, a reduced-dimension matrix is first utilised to transform the high dimension of received signal data into low dimension one. Then, a low-dimension real-value covariance matrix is obtained by forward-backward (FB) averaging and unitary transformation. The DOA of targets can be achieved by unitary root-MUSIC. Due to the FB averaging of received signal data and the eigendecomposition of the real-valued matrix covariance, the proposed method owns better angle estimation performance and lower computational complexity. The simulation results of the proposed method are presented and the performances are investigated and discussed.

  4. A Practical, Hardware Friendly MMSE Detector for MIMO-OFDM-Based Systems

    Directory of Open Access Journals (Sweden)

    Babak Daneshrad

    2008-04-01

    Full Text Available Design and implementation of a highly optimized MIMO (multiple-input multiple-output detector requires cooptimization of the algorithm with the underlying hardware architecture. Special attention must be paid to application requirements such as throughput, latency, and resource constraints. In this work, we focus on a highly optimized matrix inversion free 4×4 MMSE (minimum mean square error MIMO detector implementation. The work has resulted in a real-time field-programmable gate array-based implementation (FPGA- on a Xilinx Virtex-2 6000 using only 9003 logic slices, 66 multipliers, and 24 Block RAMs (less than 33% of the overall resources of this part. The design delivers over 420 Mbps sustained throughput with a small 2.77-microsecond latency. The designed 4×4 linear MMSE MIMO detector is capable of complying with the proposed IEEE 802.11n standard.

  5. Field-Theoretical Investigations of the Influence of Mutual Coupling Effects on the Capacity of MIMO Wireless Links

    Directory of Open Access Journals (Sweden)

    H. Ndoumbè Mbonjo Mbonjo

    2005-01-01

    Full Text Available We present a MIMO channel model which takes into account mutual coupling effects at the receiver and transmitter array in order to assess the influence of mutual coupling effects on the capacity of MIMO channels. We evaluate the mutual impedances using a general approach based on the electric field integral equation (EFIE and its implementation by the method of moments (MOM. We compute the capacity of a 2x2-MIMO system in a one path scenario for square half wavelength patch antenna elements and half wavelength dipole antenna elements. The capacity of the MIMO system with and without coupling increases compared to the single antenna transmission for the patch antenna elements. On the contrary for half wavelength dipole antenna elements we have found that the MIMO system degenerates to a one-transmitting, one-receiving antenna system due to mutual coupling.

  6. Fourier-Based Transmit Beampattern Design Using MIMO Radar

    KAUST Repository

    Lipor, John

    2014-05-01

    In multiple-input multiple-output (MIMO) radar settings, it is often desirable to transmit power only to a given location or set of locations defined by a beampattern. Transmit waveform design is a topic that has received much attention recently, involving synthesis of both the signal covariance matrix,, as well as the actual waveforms. Current methods involve a two-step process of designing via iterative solutions and then using to generate waveforms that fulfill practical constraints such as having a constant-envelope or drawing from a finite alphabet. In this paper, a closed-form method to design for a uniform linear array is proposed that utilizes the discrete Fourier transform (DFT) coefficients and Toeplitz matrices. The resulting covariance matrix fulfills the practical constraints such as positive semidefiniteness and the uniformelemental power constraint and provides performance similar to that of iterative methods, which require a much greater computation time. Next, a transmit architecture is presented that exploits the orthogonality of frequencies at discrete DFT values to transmit a sum of orthogonal signals from each antenna. The resulting waveforms provide a lower mean-square error than current methods at a much lower computational cost, and a simulated detection scenario demonstrates the performance advantages achieved.

  7. A Noise-Correlated Cancellation Transmission Scheme for Cooperative MIMO Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Wanni Liu

    2014-04-01

    Full Text Available A new transmission scheme based on noise-correlated cancellation (NCC is proposed, which absorbs the advantages of phase-inversion symmetric method and cooperative MIMO technology and makes full use of the correlation of noise in the adjacent channels to reduce channel noise. This paper firstly presents the implementation process of NCC transmission scheme in detail. Further, through theoretical analysis, it is showed that the signal-to-noise ratio gain which the proposed NCC transmission scheme gets is at least 4 times greater than the signal-to-noise ratio gain which the traditional cooperative MIMO transmission scheme gets. Finally, simulation experiment results also verify that the proposed NCC transmission scheme can make the channel capacity per bandwidth of cooperative MIMO Ad Hoc networks improve significantly and bit error rate (BER of the network reduce greatly, which will help to expand application scopes of cooperative MIMO Ad Hoc networks.

  8. Diversity and Multiplexing Technologies by 3D Beams in Polarized Massive MIMO Systems

    Directory of Open Access Journals (Sweden)

    Xin Su

    2016-01-01

    Full Text Available Massive multiple input, multiple output (M-MIMO technologies have been proposed to scale up data rates reaching gigabits per second in the forthcoming 5G mobile communications systems. However, one of crucial constraints is a dimension in space to implement the M-MIMO. To cope with the space constraint and to utilize more flexibility in 3D beamforming (3D-BF, we propose antenna polarization in M-MIMO systems. In this paper, we design a polarized M-MIMO (PM-MIMO system associated with 3D-BF applications, where the system architectures for diversity and multiplexing technologies achieved by polarized 3D beams are provided. Different from the conventional 3D-BF achieved by planar M-MIMO technology to control the downtilted beam in a vertical domain, the proposed PM-MIMO realizes 3D-BF via the linear combination of polarized beams. In addition, an effective array selection scheme is proposed to optimize the beam-width and to enhance system performance by the exploration of diversity and multiplexing gains; and a blind channel estimation (BCE approach is also proposed to avoid pilot contamination in PM-MIMO. Based on the Long Term Evolution-Advanced (LTE-A specification, the simulation results finally confirm the validity of our proposals.

  9. Power amplifier linearization technique with IQ imbalance and crosstalk compensation for broadband MIMO-OFDM transmitters

    Directory of Open Access Journals (Sweden)

    Werner Stefan

    2011-01-01

    Full Text Available Abstract The design of predistortion techniques for broadband multiple input multiple output-OFDM (MIMO-OFDM systems raises several implementation challenges. First, the large bandwidth of the OFDM signal requires the introduction of memory effects in the PD model. In addition, it is usual to consider an imbalanced in-phase and quadrature (IQ modulator to translate the predistorted baseband signal to RF. Furthermore, the coupling effects, which occur when the MIMO paths are implemented in the same reduced size chipset, cannot be avoided in MIMO transceivers structures. This study proposes a MIMO-PD system that linearizes the power amplifier response and compensates nonlinear crosstalk and IQ imbalance effects for each branch of the multiantenna system. Efficient recursive algorithms are presented to estimate the complete MIMO-PD coefficients. The algorithms avoid the high computational complexity in previous solutions based on least squares estimation. The performance of the proposed MIMO-PD structure is validated by simulations using a two-transmitter antenna MIMO system. Error vector magnitude and adjacent channel power ratio are evaluated showing significant improvement compared with conventional MIMO-PD systems.

  10. Unitary space vector quantization codebook design for spatial correlated limited feedback MIMO system

    Institute of Scientific and Technical Information of China (English)

    WU Ping; LI Li-hua

    2008-01-01

    In the transmitting, beamforming, and receivingcombing (TBRC) MIMO system, a codebook based feedbackstrategy is usually used to provide the transmitter with thebeamforming vector. The adopted codebook affects the systemperformance considerably. Therefore, the codebook design is akey technology in the TBRC MIMO system. In this article, theunitary space vector quantization (USVQ) codebook designcriterion is proposed to design optimal codebooks for variousspatial correlated MIMO channels. And the unitary spaceK-mean (USK) codebook generating algorithm is provided togenerate the USVQ codebooks. Simulations show that thecapacities of the feedback based TBRC systems using USVQcodebooks are very close to those of the ideal cases.

  11. Level Crossing Rate and Average Fade Duration of the Double Nakagami-m Random Process and Application in MIMO Keyhole Fading Channels

    CERN Document Server

    Zlatanov, Nikola; Karagiannidis, George K; 10.1109/LCOMM.2008.081058

    2009-01-01

    We present novel exact expressions and accurate closed-form approximations for the level crossing rate (LCR) and the average fade duration (AFD) of the double Nakagami-m random process. These results are then used to study the second order statistics of multiple input multiple output (MIMO) keyhole fading channels with space-time block coding. Numerical and computer simulation examples validate the accuracy of the presented mathematical analysis and show the tightness of the proposed approximations.

  12. The DoF Region of the Three-Receiver MIMO Broadcast Channel with Side Information and Its Relation to Index Coding Capacity

    OpenAIRE

    Asadi, Behzad; Ong, Lawrence; Johnson, Sarah J.

    2016-01-01

    We consider the three-receiver Gaussian multiple-input multiple-output (MIMO) broadcast channel with an arbitrary number of antennas at each of the transmitter and the receivers. We investigate the degrees-of-freedom (DoF) region of the channel when each receiver requests a private message, and may know some of the messages requested by the other receivers as receiver message side information (RMSI). We establish the DoF region of the channel for all 16 possible non-isomorphic RMSI configurat...

  13. Precoding design for single-RF massive MIMO systems: A large system analysis

    OpenAIRE

    Sifaou, Houssem; Kammoun, Abla; Alouini, Mohamed-Slim

    2016-01-01

    This work revisits a recently proposed precoding design for massive multiple-input multiple output (MIMO) systems that is based on the use of an instantaneous total power constraint. The main advantages of this technique lie in its suitability to single RF MIMO systems coupled with a very-high power efficiency. Such features have been proven using simulations for uncorrelated channels. Based on tools from random matrix theory, we propose in this work to analyze the performance of this precode...

  14. Achievable Rate of Multi-relay Cognitive Radio MIMO Channel with Space Alignment

    KAUST Repository

    Sboui, Lokman

    2015-04-21

    We study the impact of multiple relays on the primary user (PU) and secondary user (SU) rates of underlay MIMO cognitive radio. Both users exploit amplify-and-forward relays to communicate with the destination. A space alignment technique and a special linear precoding and decoding scheme are applied to allow the SU to use the resulting free eigenmodes. In addition, the SU can communicate over the used eigenmodes under the condition of respecting an interference constraint tolerated by the PU. At the destination, a successive interference cancellation (SIC) is performed to estimate the secondary signal. We present the explicit expressions of the optimal PU and SU powers that maximize their achievable rates. In the numerical results, we show that our scheme provides cognitive rate gain even in absence of tolerated interference. In addition, we show that increasing the number of relays enhances the PU and SU rates at low power regime and/or when the relays power is sufficiently high.

  15. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    Science.gov (United States)

    Siu, Sam; Ji, Qing; Wu, Wenhao; Song, Gangbing; Ding, Zhi

    2014-12-01

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications.

  16. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    International Nuclear Information System (INIS)

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications. (paper)

  17. Estudio de sistema MIMO multiusuario con coordinación limitada entre estaciones base

    OpenAIRE

    Garrido Plasencia, Sergio

    2013-01-01

    En este proyecto, realizaremos un estudio detallado de las ventajas y desventajas de los distintos tipos de precodificación usados en un canal de transmisión MIMO con coordinación limitada de las estaciones base en sistemas de comunicaciones inalámbricas celulares. Estudiaremos diferentes escenarios, siempre en función del número de antenas que estén transmitiendo, el número de antenas que habrá recibiendo, y la coordinación existente entre las estaciones base para poder observar las mejoras ...

  18. Experiments with Compact Antenna Arrays for MIMO Radio Communications

    CERN Document Server

    Browne, D W; Fitz, M P; Rahmat-Samii, Y

    2005-01-01

    The problem tackled in this study is one of MIMO transceiver implementation in which we consider how to design and test compact antenna arrays that have the ability to preserve the native information bearing capacity of a MIMO channel. Mutual coupling in antenna arrays is known to degrade the performance of a MIMO system. However, no tests involving compact arrays have been performed using a MIMO transceiver architecture that is capable of measuring the effect of mutual coupling on system performance. In this study, two novel compact MIMO antenna arrays were designed and integrated into a wideband MIMO radio testbed. These arrays are extremely compact yet have acceptable mutual coupling and radiation efficiency and resonate in three wide frequency bands. A measurement campaign was executed in which MIMO channel sounding measurements were taken using the compact arrays and dipole arrays in a variety of indoor environments. The MIMO transceiver used for channel sounding is able to measure the effect of mutual c...

  19. Optimal Design of Uniform Rectangular Antenna Arrays for Strong Line-of-Sight MIMO Channels

    Directory of Open Access Journals (Sweden)

    Frode Bøhagen

    2007-08-01

    Full Text Available We investigate the optimal design of uniform rectangular arrays (URAs employed in multiple-input multiple-output communications, where a strong line-of-sight (LOS component is present. A general geometrical model is introduced to model the LOS component, which allows for any orientation of the transmit and receive arrays, and incorporates the uniform linear array as a special case of the URA. A spherical wave propagation model is used. Based on this model, we derive the optimal array design equations with respect to mutual information, resulting in orthogonal LOS subchannels. The equations reveal that it is the distance between the antennas projected onto the plane perpendicular to the transmission direction that is of importance with respect to design. Further, we investigate the influence of nonoptimal design, and derive analytical expressions for the singular values of the LOS matrix as a function of the quality of the array design. To evaluate a more realistic channel, the LOS channel matrix is employed in a Ricean channel model. Performance results show that even with some deviation from the optimal design, we get better performance than in the case of uncorrelated Rayleigh subchannels.

  20. Optimal Design of Uniform Rectangular Antenna Arrays for Strong Line-of-Sight MIMO Channels

    Directory of Open Access Journals (Sweden)

    Orten Pål

    2007-01-01

    Full Text Available We investigate the optimal design of uniform rectangular arrays (URAs employed in multiple-input multiple-output communications, where a strong line-of-sight (LOS component is present. A general geometrical model is introduced to model the LOS component, which allows for any orientation of the transmit and receive arrays, and incorporates the uniform linear array as a special case of the URA. A spherical wave propagation model is used. Based on this model, we derive the optimal array design equations with respect to mutual information, resulting in orthogonal LOS subchannels. The equations reveal that it is the distance between the antennas projected onto the plane perpendicular to the transmission direction that is of importance with respect to design. Further, we investigate the influence of nonoptimal design, and derive analytical expressions for the singular values of the LOS matrix as a function of the quality of the array design. To evaluate a more realistic channel, the LOS channel matrix is employed in a Ricean channel model. Performance results show that even with some deviation from the optimal design, we get better performance than in the case of uncorrelated Rayleigh subchannels.

  1. 基于QRM-MLD的MIMO检测算法研究%QRM-MLD-based MIMO Detection Algorithm

    Institute of Scientific and Technical Information of China (English)

    张朝霞; 王琼; 刘佳

    2013-01-01

    在多输入多输出( MIMO)通信系统中,MIMO检测是发送端MIMO编码的逆过程,是根据接收到的信号及接收信号质量、信道状态信息等获得发送端发送比特的概率信息过程。通信信道矩阵的QR分解( QRD)是几种MIMO信号检测方案的基本先决条件。首先针对QRD方案进行研究,详细介绍了QRM-MLD的算法实现并进行了优化。最后对复杂度进行了统计并对仿真结果进行了分析,证明此方案可以作为MIMO检测的优选方案。%In MIMO ( multi-input multi-output ) communication system, MIMO detection is the reverse process of MIMO coding, and from the received signal and its quality and channel status information it ob-tains the bits probability information of the transmitter. The QRD( QR decomposition) of communication channel matrices is a fundamental prerequisite for several detection schemes. Firstly, the QRD methods are studied. Then the realization procedure and optimization of QRM-MLD are described in detail. Finally, the statistics of the complexity are presented, the simulation results are analyzed. It is verified that this so-lution can be used as a preferred scheme of MIMO detection.

  2. Capon-based single-snapshot DOA estimation in monostatic MIMO radar

    Science.gov (United States)

    Hassanien, Aboulnasr; Amin, Moeness G.; Zhang, Yimin D.; Ahmad, Fauzia

    2015-05-01

    We consider the problem of single snapshot direction-of-arrival (DOA) estimation of multiple targets in monostatic multiple-input multiple-output (MIMO) radar. When only a single snapshot is used, the sample covariance matrix of the data becomes non-invertible and, therefore, does not permit application of Capon-based DOA estimation techniques. On the other hand, low-resolution techniques, such as the conventional beamformer, suffer from biased estimation and fail to resolve closely spaced sources. In this paper, we propose a new Capon-based method for DOA estimation in MIMO radar using a single radar pulse. Assuming that the angular locations of the sources are known a priori to be located within a certain spatial sector, we employ multiple transmit beams to focus the transmit energy of multiple orthogonal waveforms within the desired sector. The transmit weight vectors are carefully designed such that they have the same transmit power distribution pattern. As compared to the standard MIMO radar, the proposed approach enables transmitting an arbitrary number of orthogonal waveforms. By using matched-filtering at the receiver, the data associated with each beam is extracted yielding a virtual data snapshot. The total number of virtual snapshots is equal to the number of transmit beams. By choosing the number of transmit beams to be larger than the number of receive elements, it becomes possible to form a full-rank sample covariance matrix. The Capon beamformer is then applied to estimate the DOAs of the targets of interest. The proposed method is shown to have improved DOA estimation performance as compared to conventional single-snapshot DOA estimation methods.

  3. Prediction of the eigenvectors for spatial multiplexing MIMO systems in time-varying channels

    DEFF Research Database (Denmark)

    Nguyen, Hung Tuan; Leus, Geert; Khaled, Nadia

    : In mobile communications, time varying channels make the available channel information out of date. Timely updating the channel state is an obvious solution to improve the system performance in a time varying channel. However, a better knowledge of the channel comes at the cost of a decrease in...... the system throughput. Thus, predicting the future channel conditions can improve not only the performance but also the throughput of many types of wireless systems. This is especially true for a wireless system where multiple antennas are applied at both link ends. In this paper we propose and...

  4. Linear precoding based on polynomial expansion: reducing complexity in massive MIMO

    KAUST Repository

    Mueller, Axel

    2016-02-29

    Massive multiple-input multiple-output (MIMO) techniques have the potential to bring tremendous improvements in spectral efficiency to future communication systems. Counterintuitively, the practical issues of having uncertain channel knowledge, high propagation losses, and implementing optimal non-linear precoding are solved more or less automatically by enlarging system dimensions. However, the computational precoding complexity grows with the system dimensions. For example, the close-to-optimal and relatively “antenna-efficient” regularized zero-forcing (RZF) precoding is very complicated to implement in practice, since it requires fast inversions of large matrices in every coherence period. Motivated by the high performance of RZF, we propose to replace the matrix inversion and multiplication by a truncated polynomial expansion (TPE), thereby obtaining the new TPE precoding scheme which is more suitable for real-time hardware implementation and significantly reduces the delay to the first transmitted symbol. The degree of the matrix polynomial can be adapted to the available hardware resources and enables smooth transition between simple maximum ratio transmission and more advanced RZF. By deriving new random matrix results, we obtain a deterministic expression for the asymptotic signal-to-interference-and-noise ratio (SINR) achieved by TPE precoding in massive MIMO systems. Furthermore, we provide a closed-form expression for the polynomial coefficients that maximizes this SINR. To maintain a fixed per-user rate loss as compared to RZF, the polynomial degree does not need to scale with the system, but it should be increased with the quality of the channel knowledge and the signal-to-noise ratio.

  5. Information-guided communications in MIMO systems with channel state impairments

    KAUST Repository

    Yang, Yuli

    2013-06-20

    Information-guided channel hopping (IGCH) is a promising technique for high-data-rate communications using multiple antennas for information mapping at the transmitter and optional antenna diversity at the receiver. Compared with some popular multi-antenna techniques, the advantage of this scheme is proven in ideal channel conditions, where the channel is spatially white and the perfect channel state information is assumed available at the receiver. The main objective of this paper is to present an information theoretical study on IGCH in realistic propagation environments with channel degeneracy due to spatial correlation and keyhole phenomena as well as imperfect channel estimation. It is proven that good performance promised by IGCH can be achieved in a variety of non-ideal channel conditions. Moreover, the analysis in this paper provides a convenient tool for the corresponding system design in practical operating environments. © 2013 John Wiley & Sons, Ltd.

  6. Achievable Rate of a Cognitive MIMO Multiple Access Channel With Multi-Secondary Users

    KAUST Repository

    Sboui, Lokman

    2015-03-01

    We study the secondary sum-rate of an underlay cognitive multiple access channel consisting of a primary user and multiple secondary users (SUs) communicating with a common destination. We propose a particular linear precoding and SU selection scheme that maximize the cognitive sum-rate. This scheme is based on space alignment strategy allowing SUs to share the spectrum without interfering with each other. We derive the optimal power allocation for each selected SU after applying perfect or imperfect successive interference cancellation. Numerical results show that the proposed scheme provides a significant sum-rate improvement as the number of SUs increases. In addition, it achieves almost the same performance as an exhaustive search selection, mainly in low and high power ranges. © 1997-2012 IEEE.

  7. Caracterización MIMO de una esquina mediante medidas

    OpenAIRE

    Ibernón Fernández, Rubén; Molina García-Pardo, José María; Juan Llacer, Leandro

    2006-01-01

    This paper presents results on capacity, correlation and K-factor for a 4x4 MIMO system in a microcellular environment. A MIMO channel sounder based on a multiport network analyzer and a fast switch controlled by a laptop has been used. LoS and NLoS situations are distinguished for three antenna elements separation of the arrays each. It has been appreciated a low capacity in some positions of the NLoS situation in spite of a not very high correlation. Los autores e...

  8. A cross-layer resource allocation scheme for spatial multiplexing-based MIMO-OFDMA systems

    Directory of Open Access Journals (Sweden)

    Al-Shatri Hussein

    2011-01-01

    Full Text Available Abstract We investigate the resource allocation problem for the downlink of a multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA system. The sum rate maximization itself cannot cope with fairness among users. Hence, we address this problem in the context of the utility-based resource allocation presented in earlier papers. This resource allocation method allows to enhance the efficiency and guarantee fairness among users by exploiting multiuser diversity, frequency diversity, as well as time diversity. In this paper, we treat the overall utility as the quality of service indicator and design utility functions with respect to the average transmission rate in order to simultaneously provide two services, real-time and best-effort. Since the optimal solutions are extremely computationally complex to obtain, we propose a suboptimal joint subchannel and power control algorithm that converges very fast and simplifies the MIMO resource allocation problem into a single-input single-output resource allocation problem. Simulation results indicate that using the proposed method achieves near-optimum solutions, and the available resources are distributed more fairly among users.

  9. Performance analysis of distributed cluster-based MAC protocol for multiuser MIMO wireless networks

    Directory of Open Access Journals (Sweden)

    Ettefagh Azadeh

    2011-01-01

    Full Text Available Abstract It is known that multiuser multiple-input multiple-output (MIMO communication can enhance the performance of wireless networks. It can substantially increase the spectral efficiency of wireless networks by utilising multiuser interference rather than avoiding it. This paradigm shift has most impact on the medium access control (MAC protocol because most existing MAC protocols are designed to reduce the interference. In this article, we propose a novel cluster-based carrier sense multiple access with collision avoidance (CB-CSMA/CA scheme. The proposed scheme enables multiuser MIMO transmissions in wireless local area networks (WLANs by utilising the multiuser interference cancellation capability of the physical layer. In this article we focus on the performance analysis of CB-CSMA/CA. We investigate saturation throughput applying optimum backoff parameters and in the presence of synchronisation errors. Furthermore, we study the impact of different clustering methods on non-saturation throughput. We show that CB-CSMA/CA improves throughput significantly compared to the CSMA/CA scheme used in the IEEE 802.11 system. It is a promising approach for a variety of network configurations including typical infrastructure WLANs as well as many other wireless cooperative networks.

  10. PMI-based MIMO OFDM PHY Integrated Key Exchange (P-MOPI) Scheme

    CERN Document Server

    Lan, Pang-Chang; Lee, Chia-Han; Yeh, Ping-Cheng; Cheng, Chen-Mou

    2011-01-01

    In the literature, J.-P. Cheng et al. have proposed the MIMO-OFDM PHY integrated (MOPI) scheme for achieving physical-layer security in practice without using any cryptographic ciphers. The MOPI scheme uses channel sounding and physical-layer network coding (PNC) to prevent eavesdroppers from learning the channel state information (CSI). Nevertheless, due to the use of multiple antennas for PNC at transmitter and beamforming at receiver, it is not possible to have spatial multiplexing nor use space-time codes in our previous MOPI scheme. In this paper, we propose a variant of the MOPI scheme, called P-MOPI, that works with a cryptographic cipher and utilizes precoding matrix index (PMI) as an efficient key-exchange mechanism. With channel sounding, the PMI is only known between the transmitter and the legal receiver. The shared key can then be used, e.g., as the seed to generate pseudo random bit sequences for securing subsequent transmissions using a stream cipher. By applying the same techniques at independ...

  11. Multiuser Beamforming with Limited Feedback for FDD Massive MIMO Systems

    Directory of Open Access Journals (Sweden)

    Senyao Zheng

    2016-01-01

    Full Text Available This paper discusses the multiuser beamforming in FDD massive MIMO systems. It first introduces the feature of FDD massive MIMO systems to implement multiuser beamforming schemes. After that, considering the realistic implementation of multiuser beamforming scheme in FDD massive MIMO systems, it introduces the knowledge of channel quantization. In the main part of the paper, we introduce two traditional multiuser beamforming schemes and analyse their merits and demerits. Based on these, we propose a novel multiuser beamforming scheme to flexibly combine the merits of the traditional beamforming schemes. In the final part of the paper, we give some simulation results to compare the beamforming schemes mentioned in the paper. These simulation results show the superiority of the proposed beamforming scheme.

  12. On Data and Parameter Estimation Using the Variational Bayesian EM-algorithm for Block-fading Frequency-selective MIMO Channels

    DEFF Research Database (Denmark)

    Christensen, Lars P.B.; Larsen, Jan

    2006-01-01

    A general Variational Bayesian framework for iterative data and parameter estimation for coherent detection is introduced as a generalization of the EM-algorithm. Explicit solutions are given for MIMO channel estimation with Gaussian prior and noise covariance estimation with inverse-Wishart prior....... Simulation of a GSM-like system provides empirical proof that the VBEM-algorithm is able to provide better performance than the EM-algorithm. However, if the posterior distribution is highly peaked, the VBEM-algorithm approaches the EM-algorithm and the gain disappears. The potential gain is therefore...

  13. Design and Implementation of Digital Down-conversion Based on MIMO-OFDM Digital Receiver%基于MIMO-OFDM接收机的数字下变频设计与实现

    Institute of Scientific and Technical Information of China (English)

    廖海黔; 吴皓威; 杨力生

    2013-01-01

    In order to meet the specific requirements for digital down-conversion of MIMO-OFDM receiver,the program of digital down-conversion is designed and implemented based on ASIC.GC5016 chip and A/D sampler chip are configured and controlled by FPGA.Meanwhile the digital down-conversion schematic block diagram of MIMO-OFDM receiver,the implementation scheme of MIMO-OFDM receiver,the signal processing flowchart in the GC5016 and the block diagram of FPGA functional module are presented.The experiment result shows that this scheme has not only good performance but good programmable ability in digital down-conversion.%为了满足MIMO-OFDM接收机的数字下变频设计要求,设计并实现了基于专业芯片的数字下变频方案,主要使用FPGA对GC5016芯片、A/D采样芯片进行配置和控制.同时,给出了MIMO-OFDM接收机的数字下变频原理框图、MIMO-OFDM接收机实现方案框图、GC5016内部信号处理流程图以及FPGA功能模块框图.实验结果表明,本设计方案不仅具有优良的数字下变频性能,而且具有良好的可编程能力.

  14. Receiver Architectures for MIMO-OFDM Based on a Combined VMP-SP Algorithm

    DEFF Research Database (Denmark)

    Manchón, Carles Navarro; Kirkelund, Gunvor Elisabeth; Riegler, Erwin;

    2011-01-01

    Iterative information processing, either based on heuristics or analytical frameworks, has been shown to be a very powerful tool for the design of efficient, yet feasible, wireless receiver architectures. Within this context, algorithms performing message-passing on a probabilistic graph, such as....... The numerical assessment of our solutions, based on Monte Carlo simulations, corroborates the high performance of the proposed algorithms and their superiority to heuristic approaches....... the sum-product (SP) and variational message passing (VMP) algorithms, have become increasingly popular. In this contribution, we apply a combined VMP-SP message-passing technique to the design of receivers for MIMO-ODFM systems. The message-passing equations of the combined scheme can be obtained...

  15. Diversity of MIMO Multihop Relay Channels - Part I: Amplify-and-Forward

    CERN Document Server

    Yang Sheng

    2007-01-01

    In this two-part paper, we consider the multiantenna multihop relay channels in which the source signal arrives at the destination through N independent relaying hops in series. The main concern of this work is to design relaying strategies that utilize efficiently the relays in such a way that the diversity is maximized. In part I, we focus on the amplify-and-forward (AF) strategy with which the relays simply scale the received signal and retransmit it. More specifically, we characterize the diversity-multiplexing tradeoff (DMT) of the AF scheme in a general multihop channel with arbitrary number of antennas and arbitrary number of hops. The DMT is in closed-form expression as a function of the number of antennas at each node. First, we provide some basic results on the DMT of the general Rayleigh product channels. It turns out that these results have very simple and intuitive interpretation. Then, the results are applied to the AF multihop channels which is shown to be equivalent to the Rayleigh product cha...

  16. Root-MUSIC Based Angle Estimation for MIMO Radar with Unknown Mutual Coupling

    Directory of Open Access Journals (Sweden)

    Jianfeng Li

    2014-01-01

    Full Text Available Direction of arrival (DOA estimation problem for multiple-input multiple-output (MIMO radar with unknown mutual coupling is studied, and an algorithm for the DOA estimation based on root multiple signal classification (MUSIC is proposed. Firstly, according to the Toeplitz structure of the mutual coupling matrix, output data of some specified sensors are selected to eliminate the influence of the mutual coupling. Then the reduced-dimension transformation is applied to make the computation burden lower as well as obtain a Vandermonde structure of the direction matrix. Finally, Root-MUSIC can be adopted for the angle estimation. The angle estimation performance of the proposed algorithm is better than that of estimation of signal parameters via rotational invariance techniques (ESPRIT-like algorithm and MUSIC-like algorithm. Furthermore, the proposed algorithm has lower complexity than them. The simulation results verify the effectiveness of the algorithm, and the theoretical estimation error of the algorithm is also derived.

  17. A HIGH RESOLUTION WIDE SWATH SAR METHOD BASED ON INTRA-PULSE NULL STEERING AND MIMO

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    High Resolution Wide Swath(HRWS)Synthetic Aperture Radar(SAR)often Sufiers from low Signal-to-Noise Ratio(SNR)due to small transmitting antenna,especially in phased array antenna systems.Digital Beam Forming(DBF)based on Single Input and Multiple Output(SIMO)achieves receiving array gain at the cost of increasing data rate.This letter proposes a new HRWS SAR method, which employs intra-pulse null steering to get receiving gain in elevation and decrease the data rate,and Multiple Input and Multiple Output(MIMO)using Space-Time Block Coding(STBC)in azimuth to get transmitting gain and receiving array gain simultaneously.The feasibility is verified by deduction and simulations.

  18. Diversity of MMSE MIMO Receivers

    CERN Document Server

    Mehana, Ahmed Hesham

    2011-01-01

    In most MIMO systems, the family of waterfall error curves, calculated at different spectral efficiencies, are asymptotically parallel at high SNR. In other words, most MIMO systems exhibit a single diversity value for all {\\em fixed} rates. The MIMO MMSE receiver does not follow this pattern and exhibits a varying diversity in its family of error curves. This effect cannot be captured by DMT analysis, due to the fact that all fixed rates correspond to the same multiplexing gain, thus they cannot be differentiated within DMT analysis. This work analyzes this interesting behavior of the MMSE MIMO receiver and produces the MMSE MIMO diversity at each rate. The diversity of the quasi-static flat-fading MIMO channel consisting of any arbitrary number of transmit and receive antennas is fully characterized, showing that full spatial diversity is possible for all antenna configurations if and only if the rate is within a certain bound which is a function of the number of antennas. For other rate brackets, the avail...

  19. MIMO Precoding for Networked Control Systems with Energy Harvesting Sensors

    Science.gov (United States)

    Cai, Songfu; Lau, Vincent K. N.

    2016-09-01

    In this paper, we consider a MIMO networked control system with an energy harvesting sensor, where an unstable MIMO dynamic system is connected to a controller via a MIMO fading channel. We focus on the energy harvesting and MIMO precoding design at the sensor so as to stabilize the unstable MIMO dynamic plant subject to the energy availability constraint at the sensor. Using the Lyapunov optimization approach, we propose a closed-form dynamic energy harvesting and dynamic MIMO precoding solution, which has an event-driven control structure. Furthermore, the MIMO precoding solution is shown to have an eigenvalue water-filling structure, where the water level depends on the state estimation covariance, energy queue and the channel state, and the sea bed level depends on the state estimation covariance. The proposed scheme is also compared with various baselines and we show that significant performance gains can be achieved.

  20. First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands.

    Science.gov (United States)

    Maruta, Kazuki; Iwakuni, Tatsuhiko; Ohta, Atsushi; Arai, Takuto; Shirato, Yushi; Kurosaki, Satoshi; Iizuka, Masataka

    2016-01-01

    Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity. PMID:27399715

  1. Robust Beamforming for Security in MIMO Wiretap Channels With Imperfect CSI

    Science.gov (United States)

    Mukherjee, Amitav; Swindlehurst, A. Lee

    2011-01-01

    In this paper, we investigate methods for reducing the likelihood that a message transmitted between two multiantenna nodes is intercepted by an undetected eavesdropper. In particular, we focus on the judicious transmission of artificial interference to mask the desired signal at the time it is broadcast. Unlike previous work that assumes some prior knowledge of the eavesdropper's channel and focuses on maximizing secrecy capacity, we consider the case where no information regarding the eavesdropper is available, and we use signal-to-interference-plus-noise-ratio (SINR) as our performance metric. Specifically, we focus on the problem of maximizing the amount of power available to broadcast a jamming signal intended to hide the desired signal from a potential eavesdropper, while maintaining a prespecified SINR at the desired receiver. The jamming signal is designed to be orthogonal to the information signal when it reaches the desired receiver, assuming both the receiver and the eavesdropper employ optimal beamformers and possess exact channel state information (CSI). In practice, the assumption of perfect CSI at the transmitter is often difficult to justify. Therefore, we also study the resulting performance degradation due to the presence of imperfect CSI, and we present robust beamforming schemes that recover a large fraction of the performance in the perfect CSI case. Numerical simulations verify our analytical performance predictions, and illustrate the benefit of the robust beamforming schemes.

  2. MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels

    Science.gov (United States)

    Ghassemlooy, Zabih; Popoola, Wasiu O.; Ahmadi, Vahid; Leitgeb, Erich

    In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects.

  3. Robust Beamforming for Security in MIMO Wiretap Channels with Imperfect CSI

    CERN Document Server

    Mukherjee, Amitav

    2010-01-01

    In this paper, we investigate methods for reducing the likelihood that a message transmitted between two multiantenna nodes is intercepted by an undetected eavesdropper. In particular, we focus on the judicious transmission of artificial interference to mask the desired signal at the time it is broadcast. Unlike previous work that assumes some prior knowledge of the eavesdropper's channel and focuses on maximizing secrecy capacity, we consider the case where no information regarding the eavesdropper is available, and we use signal-to-interference-plus-noise-ratio (SINR) as our performance metric. Specifically, we focus on the problem of maximizing the amount of power available to broadcast a jamming signal intended to hide the desired signal from a potential eavesdropper, while maintaining a prespecified SINR at the desired receiver. The jamming signal is designed to be orthogonal to the information signal when it reaches the desired receiver, assuming both the receiver and the eavesdropper employ optimal bea...

  4. A novel reduced-complexity group detection structure in MIMO frequency selective fading channels

    KAUST Repository

    Qaraqe, Khalid A.

    2010-09-01

    In this paper a novel reduced complexity detection method named modified symbol flipping method is introduced and its advantages on reducing the burden of the calculations at the receiver compared to the optimum maximum likelihood detection method on multiple input- multiple output frequency selective fading channels are explained. The initial concept of the symbol flipping method is derived from a preliminary detection scheme named bit flipping which was introduced in [1]. The detection structure employed in this paper is ing, detection, and cancellation. On the detection stage, the proposed method is employed and the results are compared to the group maximum likelihood detection scheme proposed in [2]. Simulation results show that a 6 dB performance gain can be achieved at the expense of a slight increase in complexity in comparison with the conventional symbol flipping scheme. © 2010 Crown.

  5. Mobile Station Spatio-Temporal Multipath Clustering of an Estimated Wideband MIMO Double-Directional Channel of a Small Urban 4.5 GHz Macrocell

    Directory of Open Access Journals (Sweden)

    Ida Ichirou

    2009-01-01

    Full Text Available Abstract Multipath clusters in a wireless channel could act as additional channels for spatial multiplexing MIMO systems. However, identifying them in order to come up with better cluster channel models has been a hurdle due to how they are defined. This paper considers the identification of these clusters at the mobile station through a middle ground approach—combining a globally optimized automatic clustering approach and manual clustering of the physical scatterers. By including the scattering verification in the cluster identification, better insight into their behavior in wireless channels would be known, especially the physical realism and eventually a more satisfactorily accurate cluster channel model could be proposed. The results show that overlapping clusters make up the majority of the observed channel, which stems from automatic clustering, whereas only a few clusters have clear delineation of their dispersion. In addition, it is difficult to judge the physical realism of overlapping clusters. This further points to a need for the physical interpretation and verification of clustering results, which is an initial step taken in this paper. From the identification results, scattering mechanisms of the clusters are presented and also their selected first and second order statistics.

  6. MimoPro: a more efficient Web-based tool for epitope prediction using phage display libraries

    Directory of Open Access Journals (Sweden)

    Guo William W

    2011-05-01

    Full Text Available Abstract Background A B-cell epitope is a group of residues on the surface of an antigen which stimulates humoral responses. Locating these epitopes on antigens is important for the purpose of effective vaccine design. In recent years, mapping affinity-selected peptides screened from a random phage display library to the native epitope has become popular in epitope prediction. These peptides, also known as mimotopes, share the similar structure and function with the corresponding native epitopes. Great effort has been made in using this similarity between such mimotopes and native epitopes in prediction, which has resulted in better outcomes than statistics-based methods can. However, it cannot maintain a high degree of satisfaction in various circumstances. Results In this study, we propose a new method that maps a group of mimotopes back to a source antigen so as to locate the interacting epitope on the antigen. The core of this method is a searching algorithm that is incorporated with both dynamic programming (DP and branch and bound (BB optimization and operated on a series of overlapping patches on the surface of a protein. These patches are then transformed to a number of graphs using an adaptable distance threshold (ADT regulated by an appropriate compactness factor (CF, a novel parameter proposed in this study. Compared with both Pep-3D-Search and PepSurf, two leading graph-based search tools, on average from the results of 18 test cases, MimoPro, the Web-based implementation of our proposed method, performed better in sensitivity, precision, and Matthews correlation coefficient (MCC than both did in epitope prediction. In addition, MimoPro is significantly faster than both Pep-3D-Search and PepSurf in processing. Conclusions Our search algorithm designed for processing well constructed graphs using an ADT regulated by CF is more sensitive and significantly faster than other graph-based approaches in epitope prediction. MimoPro is a

  7. Feedback and Precoding Techniques for MIMO Wireless Communications

    OpenAIRE

    Godana, Bruhtesfa Ebrahim

    2013-01-01

    Multiple-Input Multiple-Output (MIMO) communication has a big potential to increase the throughput and reliability of wireless communication systems. In order to exploit this potential, it is crucial to adapt transmission according to the Channel State Information (CSI). This thesis investigates selected problems on feedback, precoding and performance analysis in CSI based multi-antenna communication.Specifically, the thesis consists of three parts,  in which different research problems in si...

  8. Downlink Assisted Uplink Zero Forcing for TDD Multiuser MIMO Systems

    Directory of Open Access Journals (Sweden)

    Petri Komulainen

    2009-01-01

    Full Text Available This paper proposes practical coordinated linear transmit-receive processing schemes for the uplink (UL of multiuser multiple-input multiple-output (MIMO systems in the time division duplex (TDD mode. The base station (BS computes the transmission parameters in a centralized manner and employs downlink (DL pilot signals to convey the information of the beam selection and beamformers to be used by the terminals. When coexisting with the DL transmit-receive zero forcing, the precoded DL demodulation pilots can be reused for UL beam allocation so that no additional pilot overhead is required. Furthermore, the locally available channel state information (CSI of the effective MIMO channel is sufficient for the terminals to perform transmit power and rate allocation independently. In order to reduce the UL pilot overhead as well, we propose reusing the precoded UL demodulation pilots in turn for partial CSI sounding. The achievable sum rate of the system is evaluated in time-varying fading channels and with channel estimation. According to the results, the proposed UL transmission strategy provides increased rates compared to single-user MIMO transmission combined with user selection as well as to UL antenna selection transmission, without being sensitive to CSI uncertainty.

  9. Protocol for the application of cooperative MIMO based on clustering in sparse wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    WANG Qing-hua; QU Yu-gui; LIN Zhi-ting; BAI Rong-gang; ZHAO Bao-hua; PAN Quan-ke

    2007-01-01

    Wireless sensor networks (WSN) using cooperative multiple-input multiple-output (MIMO) communication are effective tools to collect data in several environments. However, how to apply cooperative MIMO in WSN remains a critical challenge, especially in sparse WSN. In this article, a novel clustering scheme is proposed for the application of cooperative MIMO in sparse WSN by extending the traditional low-energy adaptive clustering hierarchy (LEACH) protocol. This clustering scheme solves the problem that the cluster heads (CH) cannot find enough secondary cluster heads (SCH), which are used to cooperate and inform multiple-antenna transmitters with CHs. On the basis of this protocol, the overall energy consumption of the networks model is developed, and the optimal number of CHs is obtained. The simulation results show that this protocol is feasible for the sparse WSN. The simulation results also illustrate that this protocol provides significant energy efficiencies, even after allowing for additional overheads.

  10. Adaptive antenna selection and Tx/Rx beamforming for large-scale MIMO systems in 60 GHz channels

    OpenAIRE

    Prasad Narayan; Wang Xiaodong; Dong Ke; Zhu Shihua

    2011-01-01

    Abstract We consider a large-scale MIMO system operating in the 60 GHz band employing beamforming for high-speed data transmission. We assume that the number of RF chains is smaller than the number of antennas, which motivates the use of antenna selection to exploit the beamforming gain afforded by the large-scale antenna array. However, the system constraint that at the receiver, only a linear combination of the receive antenna outputs is available, which together with the large dimension of...

  11. Beamforming for multiuser MIMO systems

    OpenAIRE

    Toutounchian, Milad Amir

    2014-01-01

    Wireless communications systems use a multiple user scheme such as time- or frequency-division,but these do not allow truly simultaneous use of the spectrum. By deploying multiple antennas andbeamforming, it is possible, in principle, for users to share the spectrum simultaneously, and thisscenario is called the multiuser MIMO interference channel. This thesis presents new beamfomingdesign methods for this channel, derived from the convergence criteria for multi-objective optimization.Beamfor...

  12. User Effect on the MIMO Performance of a Dual Antenna LTE Handset

    DEFF Research Database (Denmark)

    Buskgaard, Emil Feldborg; Tatomirescu, Alexandru; Barrio, Samantha Caporal Del;

    2014-01-01

    This study focuses on the user influence on a MIMO antenna system in a smart phone form factor. The antenna system is designed to have a low coupling and correlation between its two antennas. The study is based on time-domain simulations of the antenna system in free space and with a head and hand...... phantom using a commercially available Finite Element Method solver. The MIMO parameters are evaluated with three different channel models. A static grip only gives one case of the user effect so the hand phantom is modified with a moving finger that is swept across the backplane of the phone. Based on...

  13. Fixed-complexity vector perturbation with Block diagonalization for MU-MIMO systems

    CERN Document Server

    Mohaisen, Manar; Chang, KyungHi; Ji, Seunghwan; Joung, Jinsoup

    2009-01-01

    Block diagonalization (BD) is an attractive technique that transforms the multi-user multiple-input multiple-output (MU-MIMO) channel into parallel single-user MIMO (SU-MIMO) channels with zero inter-user interference (IUI). In this paper, we combine the BD technique with two deterministic vector perturbation (VP) algorithms that reduce the transmit power in MU-MIMO systems with linear precoding. These techniques are the fixed-complexity sphere encoder (FSE) and the QR-decomposition with M-algorithm encoder (QRDM-E). In contrast to the conventional BD VP technique, which is based on the sphere encoder (SE), the proposed techniques have fixed complexity and a tradeoff between performance and complexity can be achieved by controlling the size of the set of candidates for the perturbation vector. Simulation results and analysis demonstrate the properness of the proposed techniques for the next generation mobile communications systems which are latency and computational complexity limited. In MU-MIMO system with ...

  14. MIMO-SAR: Opportunities and Pitfalls

    OpenAIRE

    Krieger, Gerhard

    2014-01-01

    This paper reviews advanced radar architectures that employ multiple transmit and multiple receive antennas to improve the performance of future synthetic aperture radar (SAR) systems. These advanced architectures have been dubbed multiple-input multiple-output SAR (MIMO-SAR) in analogy to MIMO communication systems. Considerable confusion arose, however, with regard to the selection of suitable waveforms for the simultaneous transmission via multiple channels. It is shown that the mere use o...

  15. MIMO-SAR and the Orthogonality Confusion

    OpenAIRE

    Krieger, Gerhard; Younis, Marwan; Huber, Sigurd; Bordoni, Federica; Patyuchenko, Anton; Kim, Junghyo; Laskowski, Piotr; Villano, Michealangelo; Rommel, Tobias; Lopez-dekker, Paco; Moreira, Alberto

    2012-01-01

    This paper reviews radar architectures that employ multiple transmit and multiple receive channels to improve the performance of synthetic aperture radar (SAR) systems. These advanced architectures have been dubbed multiple-input multiple-output SAR (MIMO-SAR) in analogy to MIMO communication systems. Considerable confusion arose, however, with regard to the selection of suitable waveforms for the simultaneous transmission via multiple antennas. In this paper, it is shown that the mere use of...

  16. Linear equalizer in MIMO radio communications systems

    OpenAIRE

    Manelis, V. B.; Kaioukov, I. V.

    2008-01-01

    A linear equalizer for MIMO radio communications systems has been considered. The weight coefficients of the MIMO equalizer were obtained in accordance with the criterion of minimum mean squared error. Using the computer simulation technique and analyzing the case study of HSDPA (High Speed Downlink Packet Access) channel it was shown that the application of equalizer made it possible to significantly improve the reception characteristics as compared with those of a conventional rake receiver.

  17. 3D Massive MIMO Systems: Modeling and Performance Analysis

    KAUST Repository

    Nadeem, Qurrat-Ul-Ain

    2015-07-30

    Multiple-input-multiple-output (MIMO) systems of current LTE releases are capable of adaptation in the azimuth only. Recently, the trend is to enhance system performance by exploiting the channel’s degrees of freedom in the elevation, which necessitates the characterization of 3D channels. We present an information-theoretic channel model for MIMO systems that supports the elevation dimension. The model is based on the principle of maximum entropy, which enables us to determine the distribution of the channel matrix consistent with the prior information on the angles. Based on this model, we provide analytical expression for the cumulative density function (CDF) of the mutual information (MI) for systems with a single receive and finite number of transmit antennas in the general signalto- interference-plus-noise-ratio (SINR) regime. The result is extended to systems with finite receive antennas in the low SINR regime. A Gaussian approximation to the asymptotic behavior of MI distribution is derived for the large number of transmit antennas and paths regime. We corroborate our analysis with simulations that study the performance gains realizable through meticulous selection of the transmit antenna downtilt angles, confirming the potential of elevation beamforming to enhance system performance. The results are directly applicable to the analysis of 5G 3D-Massive MIMO-systems.

  18. Code-Aided Estimation and Detection on Time-Varying Correlated Mimo Channels: A Factor Graph Approach

    Directory of Open Access Journals (Sweden)

    Simoens Frederik

    2006-01-01

    Full Text Available This paper concerns channel tracking in a multiantenna context for correlated flat-fading channels obeying a Gauss-Markov model. It is known that data-aided tracking of fast-fading channels requires a lot of pilot symbols in order to achieve sufficient accuracy, and hence decreases the spectral efficiency. To overcome this problem, we design a code-aided estimation scheme which exploits information from both the pilot symbols and the unknown coded data symbols. The algorithm is derived based on a factor graph representation of the system and application of the sum-product algorithm. The sum-product algorithm reveals how soft information from the decoder should be exploited for the purpose of estimation and how the information bits can be detected. Simulation results illustrate the effectiveness of our approach.

  19. Procesado Banda Base en sistemas MIMO basados en combinación analógica de antenas : del diseño teórico a la implementación FPGA : tesis doctoral

    OpenAIRE

    Elvira Arregui, Víctor

    2011-01-01

    ABSTRACT: In this thesis, we consider an analog antenna combining architecture for a MIMO wireless transceiver, while pointing out its advantages with respect to the traditional MIMO architectures. In the first part of this work, we focus on the transceiver design, especially the calculation of the beamformers that must be applied at the RF. This analysis is performed in an OFDM system under different assumptions on the channel state information. As a result, several criteria and algorithms f...

  20. A Waveform Adaptation Algorithm Based on Game Theory for MIMO Cognitive Radio%基于博弈论的MIMO认知无线电波形自适应算法

    Institute of Scientific and Technical Information of China (English)

    魏飞; 杨震

    2011-01-01

    The problem of waveform adaptation to maximize information rate in a multiple-in multiple-out cognitive radio ( MIMO-CR) network is investigated from a non-cooperative game theoretic viewpoint. The existence and uniqueness of the Nash e-quilibrium under certain circumstances is proved and a decentralized iterative water-filling algorithm with punishing price, MIMO-CR FWFA.is proposed to solve the above problem,the pricing mechanism is used to satisfy the interference-temperature constraint while achieving the Nash equilibrium, the conditions for the convergence of MIMO-CR IWFA are also provided. Simulation results show our MIMO-CR IWFA can satisfy the interference-temperature constraint perfectly and is fast convergent; and though con strained by PU' s interference-temperature, the performance of MMO-CR IWFA can still approach the classical MIMO IWFA, which does not consider the interference-temperature constraint, with the increase of co-channel interference between MIMO-CRs.%本文从非合作博弈的角度研究了MIMO认知无线电(MIMO-CR)网络中最大化信息速率的波形自适应问题,证明了在给定条件下Nash均衡的存在与唯一性,并提出了一种求解Nash均衡的带惩罚价格的分布式迭代注水算法——MIMO-CR IWFA,通过价格机制的运用使得MIMO-CR在满足主用户的干扰温度约束时最大化各自的信息速率;同时证明了在给定条件下MIMO-CR IWFA能够收敛到唯一Nash均衡解.仿真结果表明MIMO-CR IWFA具有快速收敛特性且能够很好的满足干扰温度约束;虽然受到主用户的干扰温度约束限制,MIMO-CR IWFA的性能能够随着MI-MO-CR链路之间的同信道干扰的增大而逐渐接近不考虑干扰温度约束的经典MIMO迭代注水算法(MIMO IWFA).

  1. The promise of downlink MU-MIMO for high-capacity next generation mobile broadband networks based on IEEE 802.16 m

    Directory of Open Access Journals (Sweden)

    Papathanassiou Apostolos

    2011-01-01

    Full Text Available Abstract The dramatic increase of the demand for mobile broadband services poses stringent requirements on the performance evolution of currently deployed mobile broadband networks, such as Mobile WiMAX Release 1 and 3GPP LTE Release 8. Although the combination of single-user multiple-input multiple-output (SU-MIMO and orthogonal frequency division multiple access (OFDMA provide the appropriate technologies for improving the downlink performance of third generation (3G code division multiple access (CDMA-based mobile radio systems and, thus, address the current mobile internet requirements, a fundamental paradigm shift is required to cope with the constantly increasing mobile broadband data rate and spectral efficiency requirements. Among the different technologies available for making the paradigm shift from current to next-generation mobile broadband networks, multiuser MIMO (MU-MIMO constitutes the most promising technology because of its significant performance improvement advantages. In this article, we analyze the performance of MU-MIMO under a multitude of deployment scenarios and system parameters through extensive system-level simulations which are based on widely used system-level evaluation methodologies. The target mobile broadband system used in the simulations is IEEE 802.16 m which was recently adopted by ITU-R as an IMT-Advanced technology along with 3GPP LTE-Advanced. The results provide insights into different aspects of MU-MIMO with respect to system-level performance, parameter sensitivity, and deployment scenarios, and they can be used by the mobile broadband network designer for maximizing the benefits of MU-MIMO in a scenario with specific deployment requirements and goals.

  2. Network MIMO with Linear Zero-Forcing Beamforming: Large System Analysis, Impact of Channel Estimation and Reduced-Complexity Scheduling

    CERN Document Server

    Huh, Hoon; Caire, Giuseppe

    2010-01-01

    We consider the downlink of a multi-cell system with multi-antenna base stations and single-antenna user terminals, arbitrary base station cooperation clusters, distance-dependent propagation pathloss, and general "fairness" requirements. We focus on the joint transmission from the base stations in a cooperation cluster based on linear zero-forcing beamforming, subject to sum or per-base station power constraints. Analytic expressions for the system spectral efficiency are found in the large-system limit where both the numbers of users and antennas per base station tend to infinity with a given ratio. In particular, for the per-base station constraint, we find new results in random matrix theory, yielding the squared Frobenius norm of submatrices of the Moore-Penrose pseudo-inverse for the structured non-i.i.d. channel matrix resulting from the cooperation cluster, user distribution, and path-loss coefficients. The analysis is extended to the case of non-ideal channel state information obtained through explic...

  3. Two-Stage Over-the-Air (OTA Test Method for LTE MIMO Device Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Ya Jing

    2012-01-01

    Full Text Available With MIMO technology being adopted by the wireless communication standards LTE and HSPA+, MIMO OTA research has attracted wide interest from both industry and academia. Parallel studies are underway in COST2100, CTIA, and 3GPP RAN WG4. The major test challenge for MIMO OTA is how to create a repeatable scenario which accurately reflects the MIMO antenna radiation performance in a realistic wireless propagation environment. Different MIMO OTA methods differ in the way to reproduce a specified MIMO channel model. This paper introduces a novel, flexible, and cost-effective method for measuring MIMO OTA using a two-stage approach. In the first stage, the antenna pattern is measured in an anechoic chamber using a nonintrusive approach, that is without cabled connections or modifying the device. In the second stage, the antenna pattern is convolved with the chosen channel model in a channel emulator to measure throughput using a cabled connection.

  4. Training and Feedback Optimization for Multiuser MIMO Downlink

    CERN Document Server

    Kobayashi, Mari; Caire, Giuseppe

    2009-01-01

    We consider a MIMO fading broadcast channel where the fading channel coefficients are constant over time-frequency blocks that span a coherent time $\\times$ a coherence bandwidth. In closed-loop systems, channel state information at transmitter (CSIT) is acquired by the downlink training sent by the base station and an explicit feedback from each user terminal. In open-loop systems, CSIT is obtained by exploiting uplink training and channel reciprocity. We use a tight closed-form lower bound on the ergodic achievable rate in the presence of CSIT errors in order to optimize the overall system throughput, by taking explicitly into account the overhead due to channel estimation and channel state feedback. Based on three time-frequency block models inspired by actual systems, we provide some useful guidelines for the overall system optimization. In particular, digital (quantized) feedback is found to offer a substantial advantage over analog (unquantized) feedback.

  5. Compressive Sensing for MIMO Radar

    CERN Document Server

    Yu, Yao; Poor, H Vincent

    2009-01-01

    Multiple-input multiple-output (MIMO) radar systems have been shown to achieve superior resolution as compared to traditional radar systems with the same number of transmit and receive antennas. This paper considers a distributed MIMO radar scenario, in which each transmit element is a node in a wireless network, and investigates the use of compressive sampling for direction-of-arrival (DOA) estimation. According to the theory of compressive sampling, a signal that is sparse in some domain can be recovered based on far fewer samples than required by the Nyquist sampling theorem. The DOA of targets form a sparse vector in the angle space, and therefore, compressive sampling can be applied for DOA estimation. The proposed approach achieves the superior resolution of MIMO radar with far fewer samples than other approaches. This is particularly useful in a distributed scenario, in which the results at each receive node need to be transmitted to a fusion center for further processing.

  6. Lens-based 77 GHZ MIMO radar for angular estimation in multitarget environments

    OpenAIRE

    Lutz, Steffen; Walter, Thomas; Weigel, Robert

    2014-01-01

    The demanding tasks for automotive radar systems in multitarget scenarios require an increased target separation performance and new sensor concepts. In this contribution, a highly integrated 77 GHz time domain multiplex (TDM) MIMO radar is presented. The sensor is feasible for advanced direction of arrival (DOA) estimation in azimuth and elevation. For efficient and high-quality measurements a fractional-n phased locked loop (PLL) with integrated waveform generator, enabling chirp and freque...

  7. MIMO-OFDM Chirp Waveform Diversity Design and Implementation Based on Sparse Matrix and Correlation Optimization

    Directory of Open Access Journals (Sweden)

    Wang Wen-qin

    2015-02-01

    Full Text Available The waveforms used in Multiple-Input Multiple-Output (MIMO Synthetic Aperture Radar (SAR should have a large time-bandwidth product and good ambiguity function performance. A scheme to design multiple orthogonal MIMO SAR Orthogonal Frequency Division Multiplexing (OFDM chirp waveforms by combinational sparse matrix and correlation optimization is proposed. First, the problem of MIMO SAR waveform design amounts to the associated design of hopping frequency and amplitudes. Then a iterative exhaustive search algorithm is adopted to optimally design the code matrix with the constraints minimizing the block correlation coefficient of sparse matrix and the sum of cross-correlation peaks. And the amplitudes matrix are adaptively designed by minimizing the cross-correlation peaks with the genetic algorithm. Additionally, the impacts of waveform number, hopping frequency interval and selectable frequency index are also analyzed. The simulation results verify the proposed scheme can design multiple orthogonal large time-bandwidth product OFDM chirp waveforms with low cross-correlation peak and sidelobes and it improves ambiguity performance.

  8. The Study of Indoor and Field Trials on 2×8 MIMO Architecture in TD-LTE Network

    Directory of Open Access Journals (Sweden)

    Xiang Zhang

    2013-01-01

    the networks are based on frequency division duplexing (FDD. In this paper, measurement methods of four MIMO transmission modes (TMs in time division-LTE (TD-LTE are studied and analyzed. Link level simulation is carried out to evaluate the downlink throughput for different signal-to-noise ratios and parameter settings. Furthermore, indoor and field tests are also presented in the paper to investigate how real-world propagation affects the capacity and the error performance of MIMO transmission scheme. For the indoor test, radio channel emulators are applied to generate realistic wireless fading channel, while in the field trials, a live TD-LTE experiment cellular network is built, which contains several evolved nodeBs (eNBs and a precommercial user equipment (UE. It is shown from both simulation and tests results that MIMO deployment gives a substantial performance improvement compared with the third generation wireless networks.

  9. Time-Domain Diversity in Ultra-Wideband MIMO Communications

    Directory of Open Access Journals (Sweden)

    Alain Sibille

    2005-03-01

    Full Text Available The development of ultra-wideband (UWB communications is impeded by the drastic transmitted power limitations imposed by regulation authorities due to the “polluting” character of these radio emissions with respect to existing services. Technical solutions must be researched in order either to limit the level of spectral pollution by UWB devices or to increase their reception sensitivity. In the present work, we consider pulse-based modulations and investigate time-domain multiple-input multiple-output (MIMO diversity as one such possible solution. The basic principles of time-domain diversity in the extreme (low multipath density or intermediate (dense multipath UWB regimes are addressed, which predict the possibility of a MIMO gain equal to the product Nt×Nr of the numbers of transmit/receive antenna elements when the channel is not too severe. This analysis is confirmed by simulations using a parametric empirical stochastic double-directional channel model. They confirm the potential interest of MIMO approaches solutions in order to bring a valuable performance gain in UWB communications.

  10. Performance Evaluation and Analysis of Switching Algorithms in MIMO-OFDM System with Ideal and Non-Ideal CSI

    OpenAIRE

    Yosra Mlayeh; Fethi Tlili; Fatma Rouissi; Ilham Ouachani; Adel Ghazel

    2010-01-01

    In this paper we analyzed the bit error rate performance of a switching algorithm between spatial multiplex-ing and diversity for an OFDM MIMO system with ideal channel state information. The effect of channel estimation error was studied and we verified by simulations that the spatial multiplexing outperforms the switching algorithm. Given that the switching algorithm is based on the comparison of the channel matrix Demmel condition number to a threshold, its accuracy is compromised when cha...

  11. BER Analysis with Adaptive Modulation Coding in MIMO-OFDM for WiMAX using GNU Radio

    Directory of Open Access Journals (Sweden)

    B. Siva Kumar Reddy

    2014-11-01

    Full Text Available This paper explores how MIMO increases channel capacity and how the fundamental characteristics of a MIMO system can create significant test challenges. Spatial modulation (SM is the latest developed modulation method in the field of communication. The latest research on this shows that SM is useful to achieve the multiplexing gain for the single antenna system, this avoids the inter-channel interference but the spatial modulation is inherently unable to get transmit-diversity. In other words, SM is a novel modulation technique which combines the high multiplexing gain provided by the spatial modulation and transmit-diversity gain, given by the space time block codes (STBCs technology. Different space-time block coding (STBC schemes including Alamouti’s STBC for 2 transmit antennas as well as orthogonal STBC (OSTBC for 3 and 4 transmit antennas are explored. The result of using these MIMO techniques is higher data rate or longer transmit range without requiring additional bandwidth or transmit power. This paper presents a detailed study of diversity coding for MIMO systems. In addition, adaptive modulation and coding (AMC technique in conjunction with MIMO techniques constitute a technological breakthrough that greatly helps in satisfying the ever increasing demands of wireless networks. This paper presents a performance study of Mobile WiMAX networks based on MIMO and AMC perspectives. It also describes how to implement WiMAX PHY with MIMO on software defined radio (SDR experimental setup with the help of USRP N210 as hardware and GNU Radio as software platforms.

  12. Wireless Distributed Antenna MIMO

    DEFF Research Database (Denmark)

    2015-01-01

    The present disclosure relates to system applications of multicore optical fibers. One embodiment relates to a base transceiver station for a wireless telecommunication system comprising a plurality of antenna units arranged in a MIMO configuration and adapted for transmission and/or reception of...... radio-frequency signals, an optical transmitter in the form of an electro-optic conversion unit for each of said plurality of antenna units, each electro-optic conversion unit adapted for converting an RF signal into an optical signal, a plurality of a single core optical fibers for guiding the optical...

  13. An S-FSCW Based Multi-Channel Reader System for Beamforming Applications using Surface Acoustic Wave Sensors

    Directory of Open Access Journals (Sweden)

    C. Pfeffer

    2011-12-01

    Full Text Available Interrogating multiple surface acoustic wave (SAW sensors located within the same radar beam require techniques to separate the multiple superposing SAW sensor responses. The presented multi-channel reader features four parallel transceiver channels, which are based on the switched frequency-stepped continuous-wave principle and high-speed parallelized baseband electronics. Thus classical beamforming applications including angle of arrival measurement of single SAW tags and the angular separation of multiple SAW sensors are presented and compared to a multiple-input multiple-output (MIMO approach. Due to the larger virtual array in the MIMO approach a larger aperture can be synthesized, which leads to significantly better angular separation results. The level analysis for the given system is verified by baseband-power measurements at different readout distances, considering the hardware parameters as well as the free-space propagation aspects. Finally measurements assess the maximum interrogation distance for the system.

  14. A Hybrid of Bacterial Foraging and Modified Cuckoo Search Optimization for Pilot Symbol Design in MIMO-OFDM Systems

    Directory of Open Access Journals (Sweden)

    R. Manjith

    2014-08-01

    Full Text Available Modern mobile telecommunication systems are using MIMO combined with OFDM, which is known as MIMO-OFDM systems, to provide robustness and higher spectrum efficiency. The major challenge in this scenario is to obtain an accurate channel estimation to detect information symbols, once the receiver must have the channel state information to equalize and process the received signal. Channel estimation is an essential task in MIMO-OFDM systems for coherent demodulation and data detection. Also designing pilot tones that affect the channel estimation performance is an important issue for these systems. For this reason, in this study we propose a Hybrid optimization algorithm (HBFOMCS based on Bacterial Foraging Optimization (BFO and Modified Cuckoo Search algorithm (MCS to optimize placement of the pilot tones that are used for Least Square (LS channel estimation in MIMO-OFDM systems. Simulation results show that designing pilot tones using the hybrid algorithm outperforms other considered placement strategies in terms of high system performance and low computational complexity.

  15. Spatial MAC in MIMO Communications and its Application to Underlay Cognitive Radio

    CERN Document Server

    Noam, Yair

    2012-01-01

    We propose a learning technique for MIMO secondary users (SU) to spatially coexist with Primary Users (PU). By learning the null space of the interference channel to the PU, the SU can utilize idle degrees of freedom that otherwise would be unused by the PU. This learning process does not require any handshake or explicit information exchange between the PU and the SU. The only requirement is that the PU broadcasts a periodic beacon that is a function of its noise plus interference power, through a low rate control channel. The learning process is based on energy measurements, independent of the transmission schemes of both the PU and SU, i.e. independent of their modulation, coding etc.. The proposed learning technique also provides a novel spatial division multiple access mechanism for equal-priority MIMO users sharing a common channel that highly increases the spectrum utilization compared to time based or frequency multiple access.

  16. Cognitive radar MIMO-STAP based on joint transmit and receive weight optimization%基于联合收发权值优化的认知雷达MIMO-STAP

    Institute of Scientific and Technical Information of China (English)

    张鑫; 崔琛; 王兴

    2012-01-01

    This paper studied the problem of joint transmit and receive weight optimization for cognitive radar MIMO-STAP. It proposed a method of joint space-time adaptive processing (JSTAP) both transmitter and receiver. It maximized the signal-to-interference-and-noise ratio ( SINR) by optimizing the weights of transmitter and receiver jointly. It analyzed the structure of the clutter covariance affected by the weithts of transmitter, and built the iterative updating structure of weights of MIMO-STAP. The process was as follows: the first step was to find the weight of receiver by solving the optimizing model when the weight of transmitter was considered to be constant. The second step was to find the weight of transmitter based on the characteristics of the clutter covariance matrix when the weight of receiver was considered to be constant. Then the next step was to go back to the first step, and the cycle would not stop until the optimum weight was solved. The experiment results show that JSTAP technology improves the SINR performance contrasting with the conventional STAP technology when the velocity of target is slow.%研究了认知雷达中多收多发空时自适应处理(MIMO-STAP)联合收发权值优化问题.提出了一种在收发两端联合空时自适应处理(JSTAP)的方法,该方法通过对收发权值联合寻优以获得最优的信干噪比.分析了受发射权值影响的杂波协方差矩阵结构,并基于此建立了MIMO-STAP的权值迭代更新结构.其权值迭代更新步骤为:固定发射权值,求解优化模型得到接收权值;然后固定接收权值,根据杂波协方差矩阵与发射权值的关系,得到发射权值;返回接收权值优化步骤,循环迭代以获得最优收发权值.仿真实验结果表明在慢速目标环境中,联合空时处理与常规空时处理相比,有效提高了接收端的信干噪比.

  17. Performance Evaluation for MIMO In Vivo WBAN Systems

    OpenAIRE

    He, Chao; Yang LIU; Ketterl, Thomas P.; Arrobo, Gabriel E.; Gitlin, Richard D.

    2014-01-01

    In this paper we present the performance evaluation for a MIMO in vivo WBAN system, using ANSYS HFSS and the associated complete Human Body Model. We analyzed MIMO system capacity statistically and FER performance based upon an IEEE 802.11n system model, with receiver antennas placed at various angular positions around the human body. We also analyzed MIMO system capacity with receiver antennas at the front of the body at various distances from transmitter antennas. The results were compared ...

  18. Mean value-based power allocation and ratio selection for MIMO cognitive radio systems

    KAUST Repository

    Tourki, Kamel

    2013-06-01

    In this paper, we consider a spectrum sharing cognitive radio system with ratio selection using a mean value-based power allocation strategy. We first provide the exact statistics in terms of probability density function and cumulative density function of the secondary channel gain as well as of the interference channel gain. These statistics are then used to derive exact closed form expression of the secondary outage probability. Furthermore, asymptotical analysis is derived and generalized diversity gain is deduced. We validate our analysis with simulation results in a Rayleigh fading environment. © 2013 IEEE.

  19. Free Probability based Capacity Calculation of Multiantenna Gaussian Fading Channels with Cochannel Interference

    CERN Document Server

    Chatzinotas, Symeon

    2010-01-01

    During the last decade, it has been well understood that communication over multiple antennas can increase linearly the multiplexing capacity gain and provide large spectral efficiency improvements. However, the majority of studies in this area were carried out ignoring cochannel interference. Only a small number of investigations have considered cochannel interference, but even therein simple channel models were employed, assuming identically distributed fading coefficients. In this paper, a generic model for a multi-antenna channel is presented incorporating four impairments, namely additive white Gaussian noise, flat fading, path loss and cochannel interference. Both point-to-point and multiple-access MIMO channels are considered, including the case of cooperating Base Station clusters. The asymptotic capacity limit of this channel is calculated based on an asymptotic free probability approach which exploits the additive and multiplicative free convolution in the R- and S-transform domain respectively, as ...

  20. Deployment and Implementation Strategies for Massive MIMO in 5G

    DEFF Research Database (Denmark)

    Panzner, Berthold; Zirwas, Wolfgang; Dierks, Stefan;

    2015-01-01

    Massive MIMO has emerged as one technology enabler for the next generation mobile communications 5G. The gains promised by massive MIMO are augured to overcome the capacity crunch in today's mobile networks and to pave the way for the ambitious targets of 5G. The challenge to realize massive MIMO...... for 5G is a successful and cost-efficient integration in the overall network concept. This work highlights deployment and implementation strategies for massive MIMO in the context of 5G indoor small cell scenarios. Different massive MIMO deployment scenarios are analyzed for a standard 3GPP indoor...... spatial streams is varied stepwise from equality to a factor of ten. For implementation of massive MIMO in 5G networks trends in beamforming techniques, mutually coupled subarrays, over the calibration procedure and estimated ADC performance in 2020 time-frame are discussed. Based on the debate the paper...

  1. A RECONFIGURABLE ARCHITECTURE OF TURBO DECODER FOR MIMO-HIGH SPEED DOWNLINK PACKET ACCESS

    Directory of Open Access Journals (Sweden)

    T. Yasodha

    2014-01-01

    Full Text Available A novel channel based rescheduling scheme for modern turbo convolution code is proposed by the inclusion of suboptimal and low-complex max-log-MAP algorithm. Demands for dedicated custom solutions in mobile communications and its related applications leads to a reconfigurable architecture for Turbo convolution code. This study comprises the design and performance evolution of the proposed reconfigurable architecture for channel coding scheme in MIMO-High Speed Downlink Packet Access (MIMO-HSDPA. To attain effective performance close to shannon limit in a multi channel system, flexible reconfigurable architecture is realized with 28 nm cyclone V GX 5CGXFC5C6 FPGA. We achieved throughput of 13.5 Mbps compared with the conventional HSDPA standards while consuming 53 mW.

  2. Construction of MIMO MAC Codes Achieving the Pigeon Hole Bound

    CERN Document Server

    Ernvall, Toni

    2012-01-01

    This paper provides a general construction method for multiple-input multiple-output multiple access channel codes (MIMO MAC codes) that have so called generalized full rank property. The achieved constructions give a positive answer to the question whether it is generally possible to reach the so called pigeon hole bound, that is an upper bound for the decay of determinants of MIMO-MAC channel codes.

  3. Enabling VLSI Processing Blocks for MIMO-OFDM Communications

    OpenAIRE

    Barbara Cerato; Guido Masera; Emanuele Viterbo

    2008-01-01

    Multi-input multi-output (MIMO) systems combined with orthogonal frequency-division multiplexing (OFDM) gained a wide popularity in wireless applications due to the potential of providing increased channel capacity and robustness against multipath fading channels. However these advantages come at the cost of a very high processing complexity and the efficient implementation of MIMO-OFDM receivers is today a major research topic. In this paper, efficient architectures are proposed for the hard...

  4. Multipair Massive MIMO Relaying with Pilot-Data Transmission Overlay

    OpenAIRE

    Pan, Leyuan; Dai, Yongyu; Xu, Wei; Dong, Xiaodai

    2016-01-01

    We propose a pilot-data transmission overlay scheme for multipair massive multiple-input multiple-output (MIMO) relaying systems employing either half- or full-duplex (HD or FD) communications at the relay station (RS). In the proposed scheme, pilots are transmitted in partial overlap with data to decrease the channel estimation overhead. The RS can detect the source data with minimal destination pilot interference by exploiting the asymptotic orthogonality of massive MIMO channels. Then pilo...

  5. Low complexity MIMO method based on matrix transformation for few-mode multi-core optical transmission system

    Science.gov (United States)

    Pan, Xiaolong; Liu, Bo; Li, Li; Tian, Qinghua

    2016-07-01

    This paper proposes and demonstrates a low complexity multiple-input multiple-output (MIMO) equalization digital signal processing (DSP) method for the few mode multi-core (FMMC) fiber optical transmission system. The MIMO equalization algorithm offers adaptive equalization taps according to the degree of crosstalk in cores or modes, which eliminates the interference among different modes and cores in space division multiplexing (SDM) transmission system. Compared with traditional MIMO method, the proposed scheme has increased the convergence rate by 4 times and reduced the number of finite impulse response (FIR) filters by 55% when the numbers of mode and core are three.

  6. Investigation of Doppler Effects on high mobility OFDM-MIMO systems with the support of High Altitude Platforms (HAPs)

    International Nuclear Information System (INIS)

    The merging of Orthogonal Frequency Division Multiplexing (OFDM) with Multiple-input multiple-output (MIMO) is a promising mobile air interface solution for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. This paper details the design of a highly robust and efficient OFDM-MIMO system to support permanent accessibility and higher data rates to users moving at high speeds, such as users travelling on trains. It has high relevance for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. The paper begins with a comprehensive literature review focused on both technologies. This is followed by the modelling of the OFDM-MIMO physical layer based on Simulink/Matlab that takes into consideration high vehicular mobility. Then the entire system is simulated and analysed under different encoding and channel estimation algorithms. The use of High Altitude Platform system (HAPs) technology is considered and analysed.

  7. Over the Air Testing of MIMO Capable Terminals

    DEFF Research Database (Denmark)

    Fan, Wei

    This thesis focuses on multi-probe anechoic chamber testing, which is a promising over the air (OTA) testing method to evaluate multiple-input multiple-output (MIMO) capable terminals. With MIMO technology being adopted by new wireless technologies, mobile manufacturers and cellular operators need...... standard test methods to evaluate MIMO device performance. Due to its capability to reproduce radio multipath environments in a shielded laboratory, the multi-probe anechoic chamber method has attracted great research attention. This thesis addresses various aspects related to OTA testing of MIMO capable...... devices, where the focus is on techniques to emulate radio channels in multi-probe setups with a limited number of probes. Several channel emulation techniques are proposed to create realistic 2D and 3D spatial channel models in the thesis. A novel method to calculate probe weights for the prefaded signal...

  8. Improved Successive Interference Cancellation for MIMO/UWB-Based Wireless Body Area Network

    OpenAIRE

    Jayasheela, M; Rajeswari, A.

    2012-01-01

    In body area networks, various sensors are attached to clothing or on the body or even implanted under the skin. The sensors measure such as heart beat, the record of prolonged electrocardiogram, blood pressure, and so on. In this paper, an improved Successive interference cancellation (SIC) scheme based on zero correlation zone sequences is proposed. Here ZCZ is used as a random code for TH PPM UWB system. Nodes in a WBAN are connected through wireless communication channel within a very clo...

  9. EVALUACIÓN EXPERIMENTAL DE CAPACIDAD MIMO DE ARREGLOS DE ANTENAS PIFA COMPACTOS EN BANDA DE 2.45 GHz EXPERIMENTAL EVALUATION OF MIMO CHANNEL CAPACITY FOR COMPACT ARRAYS OF PIFA ANTENNAS AT 2.45 GHz BAND

    OpenAIRE

    Héctor Carrasco E

    2007-01-01

    En este trabajo se presentan resultados experimentales de medición de canal y evaluación de capacidad MIMO (Multiple Input Multiple Output) de arrays de antenas PIFA (Planar Inverted "F" Antenna) compactos en la banda de frecuencia de 2.45 GHz, en entornos interiores ricos en multitrayecto. Se evalúan dos configuraciones básicas de arrays, Lineal y Cuadrada de cuatro antenas PIFA, cuyas características de bajo perfil y grados de libertad de construcción y configuración constituyen ventajas co...

  10. Multi-User MIMO Across Small Cells

    DEFF Research Database (Denmark)

    Finn, Danny; Ahmadi, Hamed; Cattoni, Andrea Fabio;

    2014-01-01

    The main contribution of this work is the proposal and assessment of the MU-MIMO across Small Cells concept. MU-MIMO is the spatial multiplexing of multiple users on a single time-frequency resource. In small cell networks, where the number of users per cell is low, finding suitable sets of users...... in a 21.7% increase in the spectral efficiency gain attributed to MU-MIMO, and a higher percentage increase when the initial number of users per cell is lower. Going forward, we will extend this work to also consider energy savings through switching off small cells which are emptied by the...... to be co-scheduled for MU-MIMO is not always possible. In these cases we propose MU-MIMO-based cell reassignments of users into adjacent cells to enable MU-MIMO operation. From system level simulations we found that, when the initial number of users per small cell is four, cell reassignment results...

  11. A Hybrid of Bacterial Foraging and Modified Cuckoo Search Optimization for Pilot Symbol Design in MIMO-OFDM Systems

    OpenAIRE

    R. Manjith; M. Suganthi

    2014-01-01

    Modern mobile telecommunication systems are using MIMO combined with OFDM, which is known as MIMO-OFDM systems, to provide robustness and higher spectrum efficiency. The major challenge in this scenario is to obtain an accurate channel estimation to detect information symbols, once the receiver must have the channel state information to equalize and process the received signal. Channel estimation is an essential task in MIMO-OFDM systems for coherent demodulation and data detection. Also desi...

  12. Pilot Pattern Adaptation for 5G MU-MIMO Wireless Communications

    OpenAIRE

    Ksairi, Nassar; Tomasi, Beatrice; Tomasin, Stefano

    2016-01-01

    To meet the goal of ten-fold increase in spectral efficiency, multiuser multiple-input-multiple-output (MU-MIMO) techniques capable of achieving high spatial multiplexing gains are expected to be an essential component of fifth-generation (5G) radio access systems. This increase in multiplexing gain, made possible by equipping base stations with a large number of antennas, entails a proportional increase in channel state information (CSI) acquisition overhead. This article addresses the probl...

  13. Massive MIMO Systems With Non-Ideal Hardware: Energy Efficiency, Estimation, and Capacity Limits

    OpenAIRE

    Bjornson, Emil; Hoydis, Jakob; Kountouris, Marios; Debbah, Merouane

    2014-01-01

    The use of large-scale antenna arrays can bring substantial improvements in energy and/or spectral efficiency to wireless systems due to the greatly improved spatial resolution and array gain. Recent works in the field of massive multiple-input multiple-output (MIMO) show that the user channels decorrelate when the number of antennas at the base stations (BSs) increases, thus strong signal gains are achievable with little inter-user interference. Since these results rely on asymptotics, it is...

  14. Direction synthesis in DOA estimation for monostatic multiple input multiple output (MIMO) radar based on synthetic impulse and aperture radar (SIAR) and its performance analysis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new direction synthetic method for monostatic multiple input multiple output (MIMO) radar is presented based on synthetic impulse and aperture radar (SIAR) system. Concerned with the monostatic MIMO radar which simultaneously emits orthogonal signals with multi-carrier-frequency and possesses sparsely distributed transmitting and receiving arrays with respective location, as well as the situation for the presence of multipath propagation in the low flying target’s echo, the method integrates the aperture of the transmitting arrays with the receiving arrays to form the digital beam-forming (DBF) in azimuth and elevation dimensions. And a study has been made of planar general MUSIC algorithm based on decorrelating the multipath signals of multi-carrier-frequency MIMO radar. Through compensat-ing the phase delay of both the transmitting and the receiving arrays and synthe-sizing the transmitting beam in two dimensions at the receiver, the angular resolu-tion and measurement accuracy are improved and the computational complexity is reduced after transforming the three-dimensional (3D) parameter estimation prob-lem into a two-dimensional (2D) one. Finally, the Cramer-Rao Bounds (CRBs) of DOA estimation for azimuth and elevation is put forward with the exsiting multipath propagation. Results of computer simulation demonstrate the validity of the new method.

  15. A novel mirror diversity receiver for indoor MIMO visible light

    KAUST Repository

    Park, Ki-Hong

    2016-03-01

    In this paper, we propose and study a non-imaging receiver design reducing the correlation of channel matrix for indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems. Contrary to previous works, our proposed mirror diversity receiver (MDR) not only blocks the reception of light on one specific direction but also improves the channel gain on the other direction by receiving the light reflected by a mirror deployed between the photodetectors. We analyze the channel capacity and optimal height of mirror in terms of maximum channel capacity for a 2 -by-2 MIMO-VLC system in a 2-dimensional geometric model.We prove that this constructive and destructive effects in channel matrix resulting from our proposed MDR are more beneficial to obtain well-conditioned channel matrix which is suitable for implementing spatial-multiplexing MIMO-VLC systems in order to support high data rate.

  16. An improved scheme based on log-likelihood-ratio for lattice reduction-aided MIMO detection

    Science.gov (United States)

    Song, Yunchao; Liu, Chen; Lu, Feng

    2016-01-01

    Lattice reduction (LR)-aided detectors have been shown great potentials in wireless communications for their low complexity and low bit-error-rate (BER) performance. The LR algorithms use the unimodular transformation to improve the orthogonality of the channel matrix. However, the LR algorithms only utilize the channel state information (CSI) and do not take account for the received signal, which is also important information in enhancing the performance of the detectors. In this paper, we make a readjustment of the received signal in the LR domain and propose a new scheme which is based on the log-likelihood-ratio (LLR) criterion to improve the LR-aided detectors. The motivation of using the LLR criterion is that it utilizes both the received signal and the CSI, so that it can provide exact pairwise error probabilities (PEPs) of the symbols. Then, in the proposed scheme, we design the LLR-based transformation algorithm (TA) which uses the unimodular transformation to minimize the PEPs of the symbols by the LLR criterion. Note that the PEPs of the symbols affect the error propagation in the vertical Bell Laboratories Layered Space-Time (VBLAST) detector, and decreasing the PEPs can reduce the error propagation in the VBLAST detectors; thus, our LLR-based TA-aided VBLAST detectors will exhibit better BER performance than the previous LR-aided VBLAST detectors. Both the BER performance and the computational complexity are demonstrated through the simulation results.

  17. Orthogonal beamforming using Gram-Schmidt orthogonalization for multi-user MIMO downlink system

    Directory of Open Access Journals (Sweden)

    Matsumura Kunitaka

    2011-01-01

    Full Text Available Abstract Simultaneous transmission to multiple users using orthogonal beamforming, known as space-division multiple-access (SDMA, is capable of achieving very high throughput in multiple-input multiple-output (MIMO broadcast channel. In this paper, we propose a new orthogonal beamforming algorithm to achieve high capacity performance in MIMO broadcast channel. In the proposed method, the base station generates a unitary beamforming vector set using Gram-Schmidt orthogonalization. We extend the algorithm of opportunistic SDMA with limited feedback (LF-OSDMA to guarantee that the system never loses multiplexing gain for fair comparison with the proposed method by informing unallocated beams. We show that the proposed method can achieve a significantly higher sum capacity than LF-OSDMA and the extended LF-OSDMA without a large increase in the amount of feedback bits and latency.

  18. Performance and Complexity Evaluation of Iterative Receiver for Coded MIMO-OFDM Systems

    Directory of Open Access Journals (Sweden)

    Rida El Chall

    2016-01-01

    Full Text Available Multiple-input multiple-output (MIMO technology in combination with channel coding technique is a promising solution for reliable high data rate transmission in future wireless communication systems. However, these technologies pose significant challenges for the design of an iterative receiver. In this paper, an efficient receiver combining soft-input soft-output (SISO detection based on low-complexity K-Best (LC-K-Best decoder with various forward error correction codes, namely, LTE turbo decoder and LDPC decoder, is investigated. We first investigate the convergence behaviors of the iterative MIMO receivers to determine the required inner and outer iterations. Consequently, the performance of LC-K-Best based receiver is evaluated in various LTE channel environments and compared with other MIMO detection schemes. Moreover, the computational complexity of the iterative receiver with different channel coding techniques is evaluated and compared with different modulation orders and coding rates. Simulation results show that LC-K-Best based receiver achieves satisfactory performance-complexity trade-offs.

  19. Interference Cancellation Using Replica Signal for HTRCI-MIMO/OFDM in Time-Variant Large Delay Spread Longer Than Guard Interval

    Directory of Open Access Journals (Sweden)

    Yuta Ida

    2012-01-01

    Full Text Available Orthogonal frequency division multiplexing (OFDM and multiple-input multiple-output (MIMO are generally known as the effective techniques for high data rate services. In MIMO/OFDM systems, the channel estimation (CE is very important to obtain an accurate channel state information (CSI. However, since the orthogonal pilot-based CE requires the large number of pilot symbols, the total transmission rate is degraded. To mitigate this problem, a high time resolution carrier interferometry (HTRCI for MIMO/OFDM has been proposed. In wireless communication systems, if the maximum delay spread is longer than the guard interval (GI, the system performance is significantly degraded due to the intersymbol interference (ISI and intercarrier interference (ICI. However, the conventional HTRCI-MIMO/OFDM does not consider the case with the time-variant large delay spread longer than the GI. In this paper, we propose the ISI and ICI compensation methods for a HTRCI-MIMO/OFDM in the time-variant large delay spread longer than the GI.

  20. Energy Balance Routing Algorithm Based on Virtual MIMO Scheme for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jianpo Li

    2014-01-01

    Full Text Available Wireless sensor networks are usually energy limited and therefore an energy-efficient routing algorithm is desired for prolonging the network lifetime. In this paper, we propose a new energy balance routing algorithm which has the following three improvements over the conventional LEACH algorithm. Firstly, we propose a new cluster head selection scheme by taking into consideration the remaining energy and the most recent energy consumption of the nodes and the entire network. In this way, the sensor nodes with smaller remaining energy or larger energy consumption will be much less likely to be chosen as cluster heads. Secondly, according to the ratio of remaining energy to distance, cooperative nodes are selected to form virtual MIMO structures. It mitigates the uneven distribution of clusters and the unbalanced energy consumption of the whole network. Thirdly, we construct a comprehensive energy consumption model, which can reflect more realistically the practical energy consumption. Numerical simulations analyze the influences of cooperative node numbers and cluster head node numbers on the network lifetime. It is shown that the energy consumption of the proposed routing algorithm is lower than the conventional LEACH algorithm and for the simulation example the network lifetime is prolonged about 25%.

  1. NOVEL DECODING OF SQUARE QAM MODULATED MIMO SYSTEMS BASED ON TURBO MULTIUSER DETECTION

    Institute of Scientific and Technical Information of China (English)

    Zheng Jianping; Bai Baoming; Wang Xinmei

    2008-01-01

    By introducing the bit-level multi-stream coded Layered Space-Time (LST) transmitter along with a novel iterative MultiStage Decoding (MSD) at the receiver, the paper shows how to achieve the near-capacity performance of the Multiple-Input Multiple-Output (MIMO) systems with square Quadrature Amplitude Modulation (QAM). In the proposed iterative MSD scheme, the detection at each stage is equivalent to multiuser detection of synchronous Code Division Multiple Access (CDMA) multiuser systems with the aid of the binary representation of the transmitted symbols. Therefore, the optimal Soft-Input Soft-Output (SISO) multiuser detection and low-complexity SISO multiuser detection can be utilized herein. And the proposed scheme with low-complexity SISO multiuser detection has polynomial complexity in the number of transmit antennas M, the number of receive antennas N, and the number of bits per constellation point Mc. Simulation results demonstrate that the proposed scheme has similar Bit Error Rate (BER) performance to that of the known Iterative Tree Search (ITS) detection.

  2. Design of Massive-MIMO-NOMA With Limited Feedback

    Science.gov (United States)

    Ding, Zhiguo; Poor, H. Vincent

    2016-05-01

    In this letter, a low-feedback non-orthogonal multiple access (NOMA) scheme using massive multiple-input multiple-output (MIMO) transmission is proposed. In particular, the proposed scheme can decompose a massive-MIMO-NOMA system into multiple separated single-input single-output NOMA channels, and analytical results are developed to evaluate the performance of the proposed scheme for two scenarios, with perfect user ordering and with one-bit feedback, respectively.

  3. Improved Iterative Coordinated Beamforming Based on Singular Value Decomposition for Multiuser Mimo Systems With Limited Feedforward

    Directory of Open Access Journals (Sweden)

    L. Soriano-Equigua

    2011-12-01

    Full Text Available Coordinated beamforming based on singular value decomposition is an iterative method to jointly optimize thetransmit beamformers and receive combiners, to achieve high levels of sum rates in the downlink of multiusersystems, by exploiting the multi-dimensional wireless channel created by multiple transmit and receive antennas. The optimization is done at the base station and the quantized beamformers are sent to the users through a low rate link.In this work, we propose to optimize this algorithm by reducing the number of iterations and improving its uncoded bit error rate performance. Simulation results show that our proposal achieves a better bit error rate with a lower number of iterations than the original algorithm.

  4. On detection performance and system configuration of MIMO radar

    Institute of Scientific and Technical Information of China (English)

    TANG Jun; WU Yong; PENG YingNing; WANG XiuTan

    2009-01-01

    Multiple-input multiple-output (MIMO) radar is a new concept with some new characteristics, such as multiple orthogonal waveforms and omnidirectional coverage. Based on Stein's lemma, we use relative entropy as a precise and general measure of error exponent to study detection performance for both MIMO radar and phased array radar. And based on derived analytical results, we further study the system configuration problem of Bistatic MIMO radar systems, where transmitters and receivers are located in different positions. Some interesting results are presented. For phased array radar, when the total numbers of transmitters and receivers are fixed, we should always make the number of transmitters equal to the number of receivers. For MIMO radar, we should use a small number of transmitters in low signal noise ratio (SNR) region, and make the number of transmitters equal to the number of receivers in high SNR region. These results are instructive for deployment of bistatic MIMO radar systems in the future.

  5. Analogue MIMO Detection

    Directory of Open Access Journals (Sweden)

    McNamara Darren

    2006-01-01

    Full Text Available In this contribution we propose an analogue receiver that can perform turbo detection in MIMO systems. We present the case for a receiver that is built from nonlinear analogue devices, which perform detection in a "free-flow" network (no notion of iterations. This contribution can be viewed as an extension of analogue turbo decoder concepts to include MIMO detection. These first analogue implementations report reductions of few orders of magnitude in the number of required transistors and in consumed energy, and the same order of improvement in processing speed. It is anticipated that such analogue MIMO decoder could bring about the same advantages, when compared to traditional digital implementations.

  6. Design and Prototyping Flow of Flexible and Efficient NISC-Based Architectures for MIMO Turbo Equalization and Demapping †

    Directory of Open Access Journals (Sweden)

    Mostafa Rizk

    2016-08-01

    Full Text Available In the domain of digital wireless communication, flexible design implementations are increasingly explored for different applications in order to cope with diverse system configurations imposed by the emerging wireless communication standards. In fact, shrinking the design time to meet market pressure, on the one hand, and adding the emerging flexibility requirement and, hence, increasing system complexity, on the other hand, require a productive design approach that also ensures final design quality. The no instruction set computer (NISC approach fulfills these design requirements by eliminating the instruction set overhead. The approach offers static scheduling of the datapath, automated register transfer language (RTLsynthesis and allows the designer to have direct control of hardware resources. This paper presents a complete NISC-based design and prototype flow, from architecture specification till FPGA implementation. The proposed design and prototype flow is illustrated through two case studies of flexible implementations, which are dedicated to low-complexity MIMO turbo-equalizer and a universal turbo-demapper. Moreover, the flexibility of the proposed prototypes allows supporting all communication modes defined in the emerging wireless communication standards, such LTE, LTE-Advanced, WiMAX, WiFi and DVB-RCS. For each prototype, its functionality is evaluated, and the resultant performance is verified for all system configurations.

  7. Programmable MIMO detectors

    OpenAIRE

    Janhunen, J. (Janne)

    2011-01-01

    Abstract The multiple-input multiple-output (MIMO) technique combined with an orthogonal frequency division multiplexing (MIMO--OFDM) has been introduced as a promising approach for the ever increasing capacity and quality of service (QoS) requirements for wireless communication systems. An efficient radio spectrum utilization expects a flexible transceiver solution, which has been the reason for the development of the software defined radio (SDR) technologies which in their turn are expe...

  8. Ultra Low Complexity Soft Output Detector for Non-Binary LDPC Coded Large MIMO Systems

    CERN Document Server

    Suthisopapan, Puripong; Kasai, Kenta; Imtawil, Virasit

    2012-01-01

    The theoretic results of MIMO capacity tell us that the higher the number of antennas are employed, the higher the transmission rate is. This makes MIMO systems with hundreds of antennas very attractive but one of the major problems that obstructs such large dimensional MIMO systems from the practical realization is a high complexity of the MIMO detector. We present in this paper the new soft output MIMO detector based on matched filtering that can be applied to the large MIMO systems which are coded by the powerful non-binary LDPC codes. The per-bit complexity of the proposed detector is just 0.28% to that of low complexity soft output MMSE detector and scales only linearly with a number of antennas. Furthermore, the coded performances with small information length 800 bits are within 4.2 dB from the associated MIMO capacity.

  9. MU-MIMO Downlink Proactive Scheduling Based on Associative Interference%MU-MIMO下行链路基于关联干扰的先验式用户调度

    Institute of Scientific and Technical Information of China (English)

    李钊; 刘瑞雪; 王琳; 马丹

    2014-01-01

    In this paper a proactive scheduling algorithm is proposed based on associative interference of spatial subchannels for MU-MIMO downlink (broadcast) channel. The strategy converts user scheduling into subchannel selection issue. With comprehensive consideration of candidate subchannel transmission gain, along with mutual interference among candidate and selected subchannels, as well as those to be selected potentially. A set of subchannels with less mutual interference are achieved. Simulation results show that by choosing proper associative interference parameters, the proposed algorithm can achieve good tradeoff between computational complexity and transmission performance, and improve system sum rate effectively.%该文针对 MU-MIMO 下行(广播)信道提出一种基于空间子信道关联干扰的先验式调度算法。该方法将用户调度转换为子信道的选择问题,通过综合考虑候选子信道的传输增益,以及候选者与已选的和潜在的、将来可能被选中的子信道间的相互干扰,获得一组相互干扰较小的子信道。仿真结果表明,合理地选取关联干扰参数,该算法能够获得计算复杂度与传输性能的良好折中,有效改善系统和速率。

  10. A Basic Unified Context for Evaluating the Beam Forming and MIMO Options in a Wireless Link

    CERN Document Server

    Chizhik, Dmitry; Valenzuela, Reinaldo A

    2011-01-01

    For one isolated wireless link we take a unified look at simple beamforming (BF) as contrasted with MIMO to see how both emerge and under which conditions advantage goes to one or the other. Communication is from a high base array to a user in clutter. The channel propagation model is derived from fundamentals. The base knows the power angular spectrum, but not the channel instantiation. Eigenstates of the field spatial autocorrelation are the preferred apodizations (APODs) which are drivers of the natural modes for exciting lectric fields. Preference for MIMO or BF depends on APOD spectra which are surveyed pointing to various asymptotic effects, including the maximum BF gain. Performance is studied under varying eigenmode power settings at 10% outage. We focus on (1,4) driving the strongest mode for BF and (4,4) driving the 4 strongest for MIMO. Results are obtained under representative parameter settings, e.g. an angular spread of 8 deg, 2 GHz carrier, 0 dB SNR and an array aperture of 1.68m (4 field decor...

  11. A NOVEL INDOOR GEO-LOCATION METHOD USING MIMO ARRAY

    Institute of Scientific and Technical Information of China (English)

    Sun Guolin; Guo Wei

    2006-01-01

    In a Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) based Wireless Local Area Network (WLAN) system, both Access Points (Aps) and Mobile Terminals (MTs) are configured with multiple antennas, to make novel indoor geo-location method possible. In this paper, we presented a novel Least Square Support Vector Machine (LS-SVM) based data fusion algorithm to fuse signal strength measurements for indoor geo-location using only a single AP with MIMO arrays. We evaluate our proposed algorithms under indoor environments by MATLAB simulations. Simulation results show that our MIMO-based algorithm is superior to conventional least square algorithm.

  12. A 2 x 2 imaging MIMO system based on LED Visible Light Communications employing space balanced coding and integrated PIN array reception

    DEFF Research Database (Denmark)

    Li, Jiehui; Xu, Yinfan; Shi, Jianyang;

    2016-01-01

    In this paper, we proposed a 2 x 2 imaging Multi-Input Multi-Output (MIMO)-Visible Light Communication (VLC) system by employing Space Balanced Coding (SBC) based on two RGB LEDs and integrated PIN array reception. We experimentally demonstrated 1.4-Gbit/s VLC transmission at a distance of 2.5 m....... The proposed imaging system not only overcomes the limitation of bandwidth existing in LEDs, but also can reject the second-order nonlinearity distortion. It turned out to be very promising to use integrated antennas in the VLC system in the future. (C) 2016 Published by Elsevier B.V....

  13. A 2×2 imaging MIMO system based on LED Visible Light Communications employing space balanced coding and integrated PIN array reception

    Science.gov (United States)

    Li, Jiehui; Xu, Yinfan; Shi, Jianyang; Wang, Yuanquan; Ji, Xinming; Ou, Haiyan; Chi, Nan

    2016-05-01

    In this paper, we proposed a 2×2 imaging Multi-Input Multi-Output (MIMO)-Visible Light Communication (VLC) system by employing Space Balanced Coding (SBC) based on two RGB LEDs and integrated PIN array reception. We experimentally demonstrated 1.4-Gbit/s VLC transmission at a distance of 2.5 m. The proposed imaging system not only overcomes the limitation of bandwidth existing in LEDs, but also can reject the second-order nonlinearity distortion. It turned out to be very promising to use integrated antennas in the VLC system in the future.

  14. Algorithms for MIMO-OFDM wireless communications

    OpenAIRE

    García-Armada, Ana

    2008-01-01

    Communications Group of University Carlos III of Madrid has designed and implemented algorithms for the improvement of the performance of MIMO-OFDM systems. This technology is capable of providing high data rate wireless communications. The developed algorithms allow, on one side, the correction of the imperfections introduced by radio-frequency equipment and, on the other side, adaptation of the transmission to the channel characteristics.

  15. A New Method of Blind Source Separation Using Single-Channel ICA Based on Higher-Order Statistics

    Directory of Open Access Journals (Sweden)

    Guangkuo Lu

    2015-01-01

    Full Text Available Methods of utilizing independent component analysis (ICA give little guidance about practical considerations for separating single-channel real-world data, in which most of them are nonlinear, nonstationary, and even chaotic in many fields. To solve this problem, a three-step method is provided in this paper. In the first step, the measured signal which is assumed to be piecewise higher order stationary time series is introduced and divided into a series of higher order stationary segments by applying a modified segmentation algorithm. Then the state space is reconstructed and the single-channel signal is transformed into a pseudo multiple input multiple output (MIMO mode using a method of nonlinear analysis based on the high order statistics (HOS. In the last step, ICA is performed on the pseudo MIMO data to decompose the single channel recording into its underlying independent components (ICs and the interested ICs are then extracted. Finally, the effectiveness and excellence of the higher order single-channel ICA (SCICA method are validated with measured data throughout experiments. Also, the proposed method in this paper is proved to be more robust under different SNR and/or embedding dimension via explicit formulae and simulations.

  16. An efficient user scheduling scheme for downlink Multiuser MIMO-OFDM systems with Block Diagonalization

    Directory of Open Access Journals (Sweden)

    Mounir Esslaoui

    2013-06-01

    Full Text Available The combination of multiuser multiple-input multiple-output (MU-MIMO technology with orthogonal frequency division multiplexing (OFDM is an attractive solution for next generation of wireless local area networks (WLANs, currently standardized within IEEE 802.11ac, and the fourth-generation (4G mobile cellular wireless systems to achieve a very high system throughput while satisfying quality of service (QoS constraints. In particular, Block Diagonalization (BD scheme is a low-complexity precoding technique for MU-MIMO downlink channels, which completely pre-cancels the multiuser interference. The major issue of the BD scheme is that the number of users that can be simultaneously supported is limited by the ratio of the number of base station transmit antennas to the number of user receive antennas. When the number of users is large, a subset of users must be selected, and selection algorithms should be designed to maximize the total system throughput. In this paper, the BD technique is extended to MU-MIMO-OFDM systems and a low complexity user scheduling algorithm is proposed to find the optimal subset of users that should transmit simultaneously, in light of the instantaneous channel state information (CSI, such that the total system sum-rate capacity is maximized. Simulation results show that the proposed scheduling algorithm achieves a good trade-off between sum-rate capacity performance and computational complexity.

  17. Modified PTS with FECs for PAPR Reduction in MIMO-OFDM System with Different Subblocks and Subcarriers

    Directory of Open Access Journals (Sweden)

    Mukunthan Pandurangan

    2011-07-01

    Full Text Available Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM systems have been proposed in the recent past for providing high data-rate services over wireless channels. When combined with space time coding it provides the advantages of space-time coding and OFDM, resulting in a spectrally efficient wideband communication system. However, MIMO OFDM systems suffer with the problem of inherent high peak-to-average power ratio (PAPR due to the intersymbol interference between the subcarriers. In order to obtain optimal PAPR reduction using the partial transmitted sequence (PTS, the total search for the number of subblocks and the rotation factors must be accomplished. As the number of subblocks and rotation factors increases, PAPR reduction improves. The number of calculation increases as the number of subblocks increases, such that complexity increases exponentially and the process delay occurs simultaneously. In this paper, a generalised framework for PAPR reduction for MIMO OFDM systems based on modified PTS using forward error-correcting codes (FECs such as Turbo codes and Golay codes are employed. PAPR reduction is jointly optimised in both the real and imaginary part by use of fast Fourier transform (FFT algorithm in the modified PTS which can be utilized for finding the optimum phase weighting factors, and can achieve the lower PAPR and computational complexity of MIMO OFDM systems. The simulation results show that the combined FEC with modified PTS technique significantly provides better PAPR reduction with reduced computational complexity compared to original PTS technique in the MIMOOFDM systems.

  18. An Orthogonal Waveform for Fully Polarimetric MIMO-SAR

    OpenAIRE

    Rommel, Tobias; Younis, Marwan; Krieger, Gerhard

    2014-01-01

    Synthetic aperture radar (SAR) with multiple transmit and receive channels (MIMO-SAR) has a higher flexibility and an improved efficiency compared to a conventional SAR system with a single channel. The multiple receive channels can be used, among other things, to increase the swath width at constant azimuth resolution or to suppress spatial interferences. However, multiple transmit channels, which transmit simultaneously in the same frequency band provide currently a challenge. Therefore, in...

  19. An Orthogonal Waveform for MIMO-SAR Applications

    OpenAIRE

    Rommel, Tobias; Huber, Sigurd; Patyuchenko, Anton; Laskowski, Piotr; Younis, Marwan; Krieger, Gerhard

    2014-01-01

    Synthetic aperture radar (SAR) with multiple transmit and receive channels (MIMO-SAR) has a higher flexibility and an improved efficiency compared to a conventional SAR system with a single channel. The multiple receive channels can be used, among other things, to increase the swath width at constant azimuth resolution or to suppress spatial interferences. However, multiple transmit channels, which transmit simultaneously in the same frequency band provide currently a challenge. The generatio...

  20. Directional Beamforming for Millimeter-Wave MIMO Systems

    OpenAIRE

    Raghavan, Vasanthan; Subramanian, Sundar; Cezanne, Juergen; Sampath, Ashwin

    2016-01-01

    The focus of this paper is on beamforming in a millimeter-wave (mmW) multi-input multi-output (MIMO) setup that has gained increasing traction in meeting the high data-rate requirements of next-generation wireless systems. For a given MIMO channel matrix, the optimality of beamforming with the dominant right-singular vector (RSV) at the transmit end and with the matched filter to the RSV at the receive end has been well-understood. When the channel matrix can be accurately captured by a physi...

  1. Over-the-Air Testing of MIMO-Capable Terminals

    DEFF Research Database (Denmark)

    Fan, Wei; Carreño, Xavier; Kyösti, Pekka;

    2015-01-01

    A new over-the-air (OTA) testing method is required for evaluating multiple-antenna systems in realistic multipath propagation environments. Antenna design and propagation channels are the two key parameters that ultimately determine the multiple-input, multiple-output (MIMO) device performance. As...... antennas are inherently included in OTA testing, it is important to also consider realistic channel models for MIMO device-performance evaluation. This article shows that the multiprobe anechoic chamber (MPAC) setup is capable of emulating realistic and accurate multipath environments, making it a suitable...

  2. Printed MIMO antenna engineering

    CERN Document Server

    Sharawi, Mohammad S

    2014-01-01

    Wireless communications has made a huge leap during the past two decades. The multiple-input-multiple-output (MIMO) technology was proposed in the 1990's as a viable solution that can overcome the data rate limit experienced by single-input-single-output (SISO) systems. This resource is focused on printed MIMO antenna system design. Printed antennas are widely used in mobile and handheld terminals due to their conformity with the device, low cost, good integration within the device elements and mechanical parts, as well as ease of fabrication.A perfect design companion for practicing engineers

  3. Mac-Phy Cross-Layer analysis and design of Mimo-Ofdm Wlans based on fast link adaptation

    OpenAIRE

    Martorell Lliteras, Gabriel

    2013-01-01

    The latestWLAN standard, known as IEEE 802.11n, has notably increased the network capacity with respect to its predecessors thanks to the incorporation of the multipleinput multiple-output (MIMO) technology. Nonetheless, the new amendment, as its previous ones, does not specify how crucial configuration mechanisms, most notably the adaptive modulation and coding (AMC) algorithm should be implemented. The AMC process has proved essential to fully exploit the system resources in ...

  4. Two-Dimensional Direction-of-Arrival Estimation for Trilinear Decomposition-Based Monostatic Cross MIMO Radar

    OpenAIRE

    Fangqing Wen; Gong Zhang

    2013-01-01

    A low complexity monostatic cross multiple-in multiple-out (MIMO) radar scheme is proposed in this paper. The minimum-redundancy linear array (MRLA) is introduced in the cross radar to improve the efficiency of the array elements. The two-dimensional direction-of-arrival (DOA) estimation problem links to the trilinear model, which automatically pairs the estimated two-dimensional angles, requiring neither eigenvalue decomposition of received signal covariance matrix nor spectral peak searchin...

  5. Cognitive MIMO Frequency Diverse Array Radar with High LPI Performance

    OpenAIRE

    Ling Huang; Kuandong Gao; Zhiming He; Jingye Cai

    2016-01-01

    Frequency diverse array (FDA) has its unique advantage in realizing low probability of intercept (LPI) technology for its dependent beam pattern. In this paper, we proposed a cognitive radar based on the frequency diverse array multiple-input multiple-output (MIMO). To implement LPI of FDA MIMO transmit signals, a scheme for array weighting design is proposed, which is to minimize the energy of the target location and maximize the energy of the receiver. This is based on the range dependent c...

  6. Line-of-Sight MIMO for Next-Generation Microwave Transmission Systems

    Institute of Scientific and Technical Information of China (English)

    Xianwei Gong; Zhifeng Yuan; Jun Xu; Liujun Hu

    2012-01-01

    Line-of-sight MIMQ (LoS MIMO) is not applicable in scattering wireless transmission scenarios, but it may be applied in LoS microwave transmission scenarios if antenna spacing (within transmit and/or receive arrays) is suitable and there is one hop distance. LoS MIMQ can improve channel capacity and performance of a transmission system. In this paper, we discuss factors affecting channel capacity and performance in LoS MIMO. We also discuss the feasibility LoS MIMO applications.

  7. Frequency Diverse Array MIMO Radar Adaptive Beamforming with Range-Dependent Interference Suppression in Target Localization

    OpenAIRE

    Kuandong Gao; Huaizong Shao; Jingye Cai; Hui Chen; Wen-Qin Wang

    2015-01-01

    Conventional multiple-input and multiple-output (MIMO) radar is a flexible technique which enjoys the advantages of phased-array radar without sacrificing its main advantages. However, due to its range-independent directivity, MIMO radar cannot mitigate nondesirable range-dependent interferences. In this paper, we propose a range-dependent interference suppression approach via frequency diverse array (FDA) MIMO radar, which offers a beamforming-based solution to suppress range-dependent inter...

  8. Energy Efficiency of Massive MIMO: Coping with Daily Load Variation

    OpenAIRE

    Hossain, M. M. Aftab; Cavdar, Cicek; Björnson, Emil; Jäntti, Riku

    2015-01-01

    Massive MIMO is a promising technique to meet the exponential growth of mobile traffic demand. However, contrary to the current systems, energy consumption of next generation networks is required to be load adaptive as the network load varies significantly throughout the day. In this paper, we propose a load adaptive multi-cell massive MIMO system where each base station (BS) adapts the number of antennas to the daily load profile (DLP) in order to maximize the downlink energy efficiency (EE)...

  9. VT-STAR design and implementation of a test bed for differential space-time block coding and MIMO channel measurements

    OpenAIRE

    Chembil Palat, Ramesh

    2002-01-01

    Next generation wireless communications require transmission of reliable high data rate services. Second generation wireless communications systems use single-input multiple-output (SIMO) channel in the reverse link, meaning one transmit antenna at the user terminal and multiple receive antennas at the base station. Recently, information theoretic research has shown an enormous potential growth in the capacity of wireless systems by using multiple antenna arrays at both ends of the link. Spac...

  10. On Feasibility of Interference Alignment in MIMO Interference Networks

    CERN Document Server

    Yetis, Cenk M; Jafar, Syed A; Kayran, Ahmet H

    2009-01-01

    We explore the feasibility of interference alignment in signal vector space -- based only on beamforming -- for K-user MIMO interference channels. Our main contribution is to relate the feasibility issue to the problem of determining the solvability of a multivariate polynomial system, considered extensively in algebraic geometry. It is well known, e.g. from Bezout's theorem, that generic polynomial systems are solvable if and only if the number of equations does not exceed the number of variables. Following this intuition, we classify signal space interference alignment problems as either proper or improper based on the number of equations and variables. Rigorous connections between feasible and proper systems are made through Bernshtein's theorem for the case where each transmitter uses only one beamforming vector. The multi-beam case introduces dependencies among the coefficients of a polynomial system so that the system is no longer generic in the sense required by both theorems. In this case, we show tha...

  11. On detection performance of MIMO radar for Rician target

    Institute of Scientific and Technical Information of China (English)

    TANG Jun; WU Yong; PENG YingNing; WANG XiuTan

    2009-01-01

    By using spatial dlversity, multiple-input-multiple-output (MIMO) radar can improve detection performance for fluctuating targets. In this paper, we propose a spatial fluctuation target model for MIMO radar, where targets are classified as non-fluctuating target, Rayleigh target and Rician target. Based on Stein's lemma, we use relative entropy to study detection performance of optimum detector for Riclan target. It is found that in low signal noise ratio (SNR) region, the performance improvement of MIMO radar for detecting Rician target depends on array gain, which is related to the number of receivers. In high SNR region, the improvement of performance depends on diversity gain, which is related to the product of the number of receivers and the number of transmitters. The conclusions of this paper are Important for designing MIMO radar system.

  12. Outdoor Urban Propagation Experiment of a Handset MIMO Antenna with a Human Phantom located in a Browsing Stance

    DEFF Research Database (Denmark)

    Yamamoto, Atsushi; Hayashi, Toshiteru; Ogawa, Koichi;

    2007-01-01

    Outdoor radio propagation experiments are presented at 2.4 GHz, using a handset MIMO antenna with two monopoles and two planar inverted-F antennas (PIFAs), adjacent to a human phantom in browsing stance. The propagation test was performed in an urban area of a city, which resulted in non lineof......-sight (NLOS) situations. In our investigation, the 4-by-4 MIMO and SISO channel capacities for the reception signals were evaluated. These measurements show that the handset MIMO antenna, close to the human operator, is capable of MIMO reception....

  13. DMT-optimal, Low ML-Complexity STBC-Schemes for Asymmetric MIMO Systems

    CERN Document Server

    Srinath, K Pavan

    2012-01-01

    For an $n_t$ transmit, $n_r$ receive antenna ($n_t\\times n_r$) MIMO system with quasi-static Rayleigh fading, it was shown by Elia et. al that schemes based on minimal-delay space-time block codes (STBCs) with a symbol rate of $n_t$ complex symbols per channel use (rate-$n_t$) and a {\\it non-vanishing determinant} (NVD) are diversity-multiplexing gain tradeoff (DMT)-optimal for arbitrary values of $n_r$. Further, explicit linear STBC-schemes (LSTBC-schemes) with the NVD property were also constructed. However, for asymmetric MIMO systems (where $n_r < n_t$), with the exception of the Alamouti code-scheme for the $2 \\times 1$ system and rate-1, diagonal STBC-schemes with NVD for an $n_t \\times 1$ system, no known minimal-delay, rate-$n_r$ STBC-scheme has been shown to be DMT-optimal. In this paper, we first obtain an enhanced sufficient criterion for an STBC-scheme to be DMT optimal and using this result, we show that for certain asymmetric MIMO systems, many well-known LSTBC-schemes which have low ML-decod...

  14. Efficient linear precoding for massive MIMO systems using truncated polynomial expansion

    KAUST Repository

    Müller, Axel

    2014-06-01

    Massive multiple-input multiple-output (MIMO) techniques have been proposed as a solution to satisfy many requirements of next generation cellular systems. One downside of massive MIMO is the increased complexity of computing the precoding, especially since the relatively \\'antenna-efficient\\' regularized zero-forcing (RZF) is preferred to simple maximum ratio transmission. We develop in this paper a new class of precoders for single-cell massive MIMO systems. It is based on truncated polynomial expansion (TPE) and mimics the advantages of RZF, while offering reduced and scalable computational complexity that can be implemented in a convenient parallel fashion. Using random matrix theory we provide a closed-form expression of the signal-to-interference-and-noise ratio under TPE precoding and compare it to previous works on RZF. Furthermore, the sum rate maximizing polynomial coefficients in TPE precoding are calculated. By simulation, we find that to maintain a fixed peruser rate loss as compared to RZF, the polynomial degree does not need to scale with the system, but it should be increased with the quality of the channel knowledge and signal-to-noise ratio. © 2014 IEEE.

  15. Energy Efficiency Maximization through Cooperative Transmit and Receive Antenna Selection for Multicell MU-MIMO System

    Directory of Open Access Journals (Sweden)

    Yanjie Dong

    2013-01-01

    Full Text Available The capacity of Multiple Input Multiple Output (MIMO system is highly related to the number of active antennas. But as the active antenna number increases, the MIMO system will consume more energy. To maximize the energy efficiency of MIMO system, we propose an antenna selection scheme which can maximize the energy efficiency of BS cluster. In the scheme, ergodic energy efficiency is derived according to large scale channel state information (CSI. Based on this ergodic energy efficiency, we introduce a cost function varied with the number of antennas, in which the effect to the energy efficiency of both the serving BS and the neighbor BS is considered. With this function, we can transform the whole system optimization problem to a sectional optimization problem and obtain a suboptimal antenna set using a heuristic algorithm. Simulation results verify that the proposed approach performs better than the comparison schemes in terms of network energy efficiency and achieves 98% network energy efficiency of the centralized antenna selection scheme. Besides, since the proposed scheme does not need the complete CSI of the neighbor BS, it can effectively reduce the signaling overhead.

  16. Joint optimization of CQI calculation and interference mitigation for user scheduling in MIMO-OFDM systems

    KAUST Repository

    Sadek, Mirette

    2011-05-01

    In MIMO-OFDM multiuser systems, user scheduling is employed as a means of multiple access. In a downlink scenario, users that share the same subcarriers of an OFDM symbol are separated through precoding in order to achieve space division multiple access (SDMA). User scheduling techniques rely on channel knowledge at the transmitter, namely, the so-called channel quality indicator (CQI). In this paper, we implement a leakage-based precoding algorithm whose purpose is twofold. First, it is used to compute a reliable CQI based on a group of precoding vectors that are adapted to the channel. Then, it implements user scheduling through using the optimum vectors for precoding, thus minimizing interference among users. We also introduce the concept of resource block size adaptivity. The resource block (RB) is defined as the least unit in an OFDM symbol that a user can be assigned to. We propose a variable RB size that adapts to the channel conditions. © 2011 IEEE.

  17. D-BLAST OFDM with Channel Estimation

    Directory of Open Access Journals (Sweden)

    Du Jianxuan

    2004-01-01

    Full Text Available Multiple-input and multiple-output (MIMO systems formed by multiple transmit and receive antennas can improve performance and increase capacity of wireless communication systems. Diagonal Bell Laboratories Layered Space-Time (D-BLAST structure offers a low-complexity solution for realizing the attractive capacity of MIMO systems. However, for broadband wireless communications, channel is frequency-selective and orthogonal frequency division multiplexing (OFDM has to be used with MIMO techniques to reduce system complexity. In this paper, we investigate D-BLAST for MIMO-OFDM systems. We develop a layerwise channel estimation algorithm which is robust to channel variation by exploiting the characteristic of the D-BLAST structure. Further improvement is made by subspace tracking to considerably reduce the error floor. Simulation results show that the layerwise estimators require 1 dB less signal-to-noise ratio (SNR than the traditional blockwise estimator for a word error rate (WER of when Doppler frequency is 40 Hz. Among the layerwise estimators, the subspace-tracking estimator provides a 0.8 dB gain for WER with 200 Hz Doppler frequency compared with the DFT-based estimator.

  18. The Capacity Gain of Orbital Angular Momentum Based Multiple-Input-Multiple-Output System

    Science.gov (United States)

    Zhang, Zhuofan; Zheng, Shilie; Chen, Yiling; Jin, Xiaofeng; Chi, Hao; Zhang, Xianmin

    2016-05-01

    Wireless communication using electromagnetic wave carrying orbital angular momentum (OAM) has attracted increasing interest in recent years, and its potential to increase channel capacity has been explored widely. In this paper, we compare the technique of using uniform linear array consist of circular traveling-wave OAM antennas for multiplexing with the conventional multiple-in-multiple-out (MIMO) communication method, and numerical results show that the OAM based MIMO system can increase channel capacity while communication distance is long enough. An equivalent model is proposed to illustrate that the OAM multiplexing system is equivalent to a conventional MIMO system with a larger element spacing, which means OAM waves could decrease the spatial correlation of MIMO channel. In addition, the effects of some system parameters, such as OAM state interval and element spacing, on the capacity advantage of OAM based MIMO are also investigated. Our results reveal that OAM waves are complementary with MIMO method. OAM waves multiplexing is suitable for long-distance line-of-sight (LoS) communications or communications in open area where the multi-path effect is weak and can be used in massive MIMO systems as well.

  19. The Capacity Gain of Orbital Angular Momentum Based Multiple-Input-Multiple-Output System.

    Science.gov (United States)

    Zhang, Zhuofan; Zheng, Shilie; Chen, Yiling; Jin, Xiaofeng; Chi, Hao; Zhang, Xianmin

    2016-01-01

    Wireless communication using electromagnetic wave carrying orbital angular momentum (OAM) has attracted increasing interest in recent years, and its potential to increase channel capacity has been explored widely. In this paper, we compare the technique of using uniform linear array consist of circular traveling-wave OAM antennas for multiplexing with the conventional multiple-in-multiple-out (MIMO) communication method, and numerical results show that the OAM based MIMO system can increase channel capacity while communication distance is long enough. An equivalent model is proposed to illustrate that the OAM multiplexing system is equivalent to a conventional MIMO system with a larger element spacing, which means OAM waves could decrease the spatial correlation of MIMO channel. In addition, the effects of some system parameters, such as OAM state interval and element spacing, on the capacity advantage of OAM based MIMO are also investigated. Our results reveal that OAM waves are complementary with MIMO method. OAM waves multiplexing is suitable for long-distance line-of-sight (LoS) communications or communications in open area where the multi-path effect is weak and can be used in massive MIMO systems as well. PMID:27146453

  20. On the transfer matrix of a MIMO system

    DEFF Research Database (Denmark)

    Bentosela, Francois; Cornean, Horia; Fleury, Bernard Henri;

    2011-01-01

    We develop a deterministic ab initio model for the input–output relationship of a multiple-input multiple-output (MIMO) wireless channel, starting from the Maxwell equations combined with Ohm's law. The main technical tools are scattering and geometric perturbation theories. The derived...

  1. Mimo radar waveform design for spectrum sharing with cellular systems a Matlab based approach

    CERN Document Server

    Khawar, Awais; Clancy, T Charles

    2016-01-01

    This book discusses spectrum sharing between cellular systems and radars. The book addresses a novel way to design radar waveforms that can enable spectrum sharing between radars and communication systems, without causing interference to communication systems, and at the same time achieving radar objectives of target detection, estimation, and tracking. The book includes a MATLAB-based approach, which provides reader with a way to learn, experiment, compare, and build on top of existing algorithms.

  2. Joint compensation of multiple RF impairments in MIMO STBC systems

    KAUST Repository

    Qi, Jian

    2011-09-01

    In this paper, we propose a compensation method for the joint effect of high-power amplifier (HPA) nonlinearity, in-phase/quadrature-phase (I/Q) imbalance and crosstalk in multiple-input multiple-output (MIMO) orthogonal space-time block coding (OSTBC) systems. The performance of the MIMO OSTBC equipped with the proposed compensation mechanism is evaluated in terms of average symbol error probability and system capacity, in Rayleigh fading channels. Numerical results are provided and show the effects on performance of several system parameters, namely, the HPA parameters, image-leakage ratio, crosstalk, numbers of antennas, and phase-shift keying modulation order. © 2011 IEEE.

  3. Multiple-Parameter Estimation Method Based on Spatio-Temporal 2-D Processing for Bistatic MIMO Radar

    Directory of Open Access Journals (Sweden)

    Shouguo Yang

    2015-12-01

    Full Text Available A novel spatio-temporal 2-dimensional (2-D processing method that can jointly estimate the transmitting-receiving azimuth and Doppler frequency for bistatic multiple-input multiple-output (MIMO radar in the presence of spatial colored noise and an unknown number of targets is proposed. In the temporal domain, the cross-correlation of the matched filters’ outputs for different time-delay sampling is used to eliminate the spatial colored noise. In the spatial domain, the proposed method uses a diagonal loading method and subspace theory to estimate the direction of departure (DOD and direction of arrival (DOA, and the Doppler frequency can then be accurately estimated through the estimation of the DOD and DOA. By skipping target number estimation and the eigenvalue decomposition (EVD of the data covariance matrix estimation and only requiring a one-dimensional search, the proposed method achieves low computational complexity. Furthermore, the proposed method is suitable for bistatic MIMO radar with an arbitrary transmitted and received geometrical configuration. The correction and efficiency of the proposed method are verified by computer simulation results.

  4. RF Transceiver Design for MIMO Wireless Communications

    CERN Document Server

    Mohammadi, Abbas

    2012-01-01

    This practical resource offers a thorough examination of RF transceiver design for MIMO communications.  Offering a practical view on MIMO wireless systems, this book extends fundamental concepts on classic wireless transceiver design techniques to MIMO transceivers. This helps reader gain a very comprehensive understanding of the subject. This in-depth volume describes many theoretical and implementation challenges on MIMO transceivers and provides the practical solutions for these issues. This comprehensive book provides thorough descriptions of MIMO theoretical concepts, MIMO single carrier and OFDM modulation, RF transceiver design concepts, power amplifier, MIMO transmitter design techniques and their RF impairments, MIMO receiver design methods, RF impairments study including nonlinearity, DC-offset, I/Q imbalance and phase noise and their compensation in OFDM and MIMO techniques. In addition, it provides the most practical techniques to realize RF front-ends in MIMO systems. This book is supported wit...

  5. Alternate transmission relaying based on interference alignment in 3-relay half-duplex MIMO systems

    KAUST Repository

    Park, Seongho

    2012-09-01

    In a half-duplex relaying, the capacity pre-log factor 1/2 is a major drawback in spectral efficiency. This paper proposes a linear precoding/decoding scheme and an alternate relaying protocol in a dual-hop half-duplex system where three relays help the communication between the source and the destination. In our proposed scheme, we consider a phase incoherent method in relays in which the source alternately transmits message signals to the different relays. In addition, we propose a linear interference alignment scheme which can suppress the inter-relay interference resulting from the phase incoherence of relaying. Based on our analysis of degrees of freedom and our simulation results, we show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying. © 2012 IEEE.

  6. Performance of Spatial Division Multiplexing MIMO with Frequency Domain Packet Scheduling

    DEFF Research Database (Denmark)

    Wei, Na; Pokhariyal, Akhilesh; Sørensen, Troels Bundgaard;

    2008-01-01

    performance bounds of SDM-FDPS. To facilitate the analysis, a unified SINR concept is utilized to make a fair comparison of MIMO schemes with different number of spatial streams. The effect of packet scheduling is included in the post-scheduling SINR distribution using an analytical model. Based on that, the......, the more practical simulation results are compared against the theoretical performance bounds. A performance loss is seen in the simulations due to realistic coding/modulation, impact of frequency selectivity, signalling constraints, imperfect channel quality indicator (CQI), etc...

  7. Low complexity symbol-wise beamforming for MIMO-OFDM systems

    KAUST Repository

    Lee, Hyun Ho

    2011-12-01

    In this paper, we consider a low complexity symbol-wise beamforming for MIMO-OFDM systems. We propose a non-iterative algorithm for the symbol-wise beamforming, which can provide the performance approaching that of the conventional symbol-wise beamforming based on the iterative algorithm. We demonstrate that our proposed scheme can reduce the computational complexity significantly. From our simulation results, it is evident that our proposed scheme leads to a negligible performance loss compared to the conventional symbol-wise beamforming regardless of spatial correlation or presence of co-channel interference. © 2011 IEEE.

  8. Optimal beamforming in MIMO systems with HPA nonlinearity

    KAUST Repository

    Qi, Jian

    2010-09-01

    In this paper, multiple-input multiple-output (MIMO) transmit beamforming (TB) systems under the consideration of nonlinear high-power amplifiers (HPAs) are investigated. The optimal beamforming scheme, with the optimal beamforming weight vector and combining vector, is proposed for MIMO systems with HPA nonlinearity. The performance of the proposed MIMO beamforming scheme in the presence of HPA nonlinearity is evaluated in terms of average symbol error probability (SEP), outage probability and system capacity, considering transmission over uncorrelated quasi-static frequency-flat Rayleigh fading channels. Numerical results are provided and show the effects of several system parameters, namely, parameters of nonlinear HPA, numbers of transmit and receive antennas, and modulation order of phase-shift keying (PSK), on performance. ©2010 IEEE.

  9. A General Design Framework for MIMO Wireless Energy Transfer With Limited Feedback

    Science.gov (United States)

    Xu, Jie; Zhang, Rui

    2016-05-01

    Multi-antenna or multiple-input multiple-output (MIMO) technique can significantly improve the efficiency of radio frequency (RF) signal enabled wireless energy transfer (WET). To fully exploit the energy beamforming gain at the energy transmitter (ET), the knowledge of channel state information (CSI) is essential, which, however, is difficult to be obtained in practice due to the hardware limitation of the energy receiver (ER). To overcome this difficulty, under a point-to-point MIMO WET setup, this paper proposes a general design framework for a new type of channel learning method based on the ER's energy measurement and feedback. Specifically, the ER measures and encodes the harvested energy levels over different training intervals into bits, and sends them to the ET via a feedback link of limited rate. Based on the energy-level feedback, the ET adjusts transmit beamforming in subsequent training intervals and obtains refined estimates of the MIMO channel by leveraging the technique of analytic center cutting plane method (ACCPM) in convex optimization. Under this general design framework, we further propose two specific feedback schemes termed energy quantization and energy comparison, where the feedback bits at each interval are generated at the ER by quantizing the measured energy level at the current interval and comparing it with those in the previous intervals, respectively. Numerical results are provided to compare the performance of the two feedback schemes. It is shown that energy quantization performs better when the number of feedback bits per interval is large, while energy comparison is more effective with small number of feedback bits.

  10. Performance of MIMO systems

    OpenAIRE

    Grande González, Patricia; Gros Vidal, Thomas

    2008-01-01

    Demand in high data rate communications, driven by internet and cellular mobile, have increased, specially in wireless local area networks, emerging home audio visual networks and multimedia services in general. The limitation of the available radio spectrum makes it impossible for the data rate needs to be accomplished by an increase in the bandwidth. The deployment of multiple antennas in the transmitter and the receiver, multiple input multiple output (MIMO), a cost effective technology, m...

  11. SmartMIMO: An Energy-Aware Adaptive MIMO-OFDM Radio Link Control for Next-Generation Wireless Local Area Networks

    Directory of Open Access Journals (Sweden)

    Wim Dehaene

    2007-12-01

    Full Text Available Multiantenna systems and more particularly those operating on multiple input and multiple output (MIMO channels are currently a must to improve wireless links spectrum efficiency and/or robustness. There exists a fundamental tradeoff between potential spectrum efficiency and robustness increase. However, multiantenna techniques also come with an overhead in silicon implementation area and power consumption due, at least, to the duplication of part of the transmitter and receiver radio front-ends. Although the area overhead may be acceptable in view of the performance improvement, low power consumption must be preserved for integration in nomadic devices. In this case, it is the tradeoff between performance (e.g., the net throughput on top of the medium access control layer and average power consumption that really matters. It has been shown that adaptive schemes were mandatory to avoid that multiantenna techniques hamper this system tradeoff. In this paper, we derive smartMIMO: an adaptive multiantenna approach which, next to simply adapting the modulation and code rate as traditionally considered, decides packet-per-packet, depending on the MIMO channel state, to use either space-division multiplexing (increasing spectrum efficiency, space-time coding (increasing robustness, or to stick to single-antenna transmission. Contrarily to many of such adaptive schemes, the focus is set on using multiantenna transmission to improve the link energy efficiency in real operation conditions. Based on a model calibrated on an existing reconfigurable multiantenna transceiver setup, the link energy efficiency with the proposed scheme is shown to be improved by up to 30% when compared to nonadaptive schemes. The average throughput is, on the other hand, improved by up to 50% when compared to single-antenna transmission.

  12. SmartMIMO: An Energy-Aware Adaptive MIMO-OFDM Radio Link Control for Next-Generation Wireless Local Area Networks

    Directory of Open Access Journals (Sweden)

    Dehaene Wim

    2007-01-01

    Full Text Available Multiantenna systems and more particularly those operating on multiple input and multiple output (MIMO channels are currently a must to improve wireless links spectrum efficiency and/or robustness. There exists a fundamental tradeoff between potential spectrum efficiency and robustness increase. However, multiantenna techniques also come with an overhead in silicon implementation area and power consumption due, at least, to the duplication of part of the transmitter and receiver radio front-ends. Although the area overhead may be acceptable in view of the performance improvement, low power consumption must be preserved for integration in nomadic devices. In this case, it is the tradeoff between performance (e.g., the net throughput on top of the medium access control layer and average power consumption that really matters. It has been shown that adaptive schemes were mandatory to avoid that multiantenna techniques hamper this system tradeoff. In this paper, we derive smartMIMO: an adaptive multiantenna approach which, next to simply adapting the modulation and code rate as traditionally considered, decides packet-per-packet, depending on the MIMO channel state, to use either space-division multiplexing (increasing spectrum efficiency, space-time coding (increasing robustness, or to stick to single-antenna transmission. Contrarily to many of such adaptive schemes, the focus is set on using multiantenna transmission to improve the link energy efficiency in real operation conditions. Based on a model calibrated on an existing reconfigurable multiantenna transceiver setup, the link energy efficiency with the proposed scheme is shown to be improved by up to 30% when compared to nonadaptive schemes. The average throughput is, on the other hand, improved by up to 50% when compared to single-antenna transmission.

  13. SEMI-BLIND CHANNEL ESTIMATION OF MULTIPLE-INPUT/MULTIPLE-OUTPUT SYSTEMS BASED ON MARKOV CHAIN MONTE CARLO METHODS

    Institute of Scientific and Technical Information of China (English)

    Jiang Wei; Xiang Haige

    2004-01-01

    This paper addresses the issues of channel estimation in a Multiple-Input/Multiple-Output (MIMO) system. Markov Chain Monte Carlo (MCMC) method is employed to jointly estimate the Channel State Information (CSI) and the transmitted signals. The deduced algorithms can work well under circumstances of low Signal-to-Noise Ratio (SNR). Simulation results are presented to demonstrate their effectiveness.

  14. Joint Multichannel Motion Compensation Method for MIMO SAR 3D Imaging

    Directory of Open Access Journals (Sweden)

    Ze-min Yang

    2015-01-01

    Full Text Available The multiple-input-multiple-output (MIMO synthetic aperture radar (SAR system with a linear antenna array can obtain 3D resolution. In practice, it suffers from both the translational motion errors and the rotational motion errors. Conventional single-channel motion compensation methods could be used to compensate the motion errors channel by channel. However, this method might not be accurate enough for all the channels. What is more, the single-channel compensation may break the coherence among channels, which would cause defocusing and false targets. In this paper, both the translational motion errors and the rotational motion errors are discussed, and a joint multichannel motion compensation method is proposed for MIMO SAR 3D imaging. It is demonstrated through simulations that the proposed method exceeds the conventional methods in accuracy. And the final MIMO SAR 3D imaging simulation confirms the validity of the proposed algorithm.

  15. A Novel Diversity-Multiplexing Tradeoff Scheme in Cooperative MIMO Based on Distributed Space-Time Coding%一种基于分布式空时码的协作MIMO分集复用折衷新方案

    Institute of Scientific and Technical Information of China (English)

    许晓荣; 章坚武; 郑宝玉

    2011-01-01

    Cooperative MIMO which is composed of multiple single antenna nodes by cooperative communication could construct multipte virtual transmit antennas. Spatial diversity gain could be obtained from this virtual MIMO multiple antenna arrays. Considered the specific features of cooperative MIMO, code cooperation strategy with distributed space-time coding is implemented in the network. An enhanced divemity-multiplexing tradeoff (DMT) scheme based on distributed space-time ceding (DSTC) in cooperative MIMO is studied. The expression of outage probability and diversity gain of two DSTC strategies are derived in detail. Based on the two DMT schemes of DSTC, the optimal DMT and outage performance of the enhanced DMT strategy could be obtained through altering the threshold of multiplexing gain adaptively. Numerical results indicate that, the proposed DMT scheme could be asymptotical to DMT upper bound in cooperative MIMO, and the corresponding outage performance is also inferior to that of upper bound. Hence, cooperative diversity gain and optimum outage behavior could be achieved simultaneously by the proposed DMT scheme for DSTC code cooperation in multi-node cooperative MIMO scenario.%协作MIMO通过多个单天线节点的相互协作构造多发射天线,以此形成一种虚拟MIMO多天线阵列获得空间分集增益.考虑到协作MIMO特点,天线间采用分布式空时编码进行编码协作.文章研究了协作MIMO中基于分布式空时码(DSTC)的分集复用折衷(DMT)新方案,该方案通过推导两种DSTC的中断概率与分集增益表达式,结合两类DSYC的DMT策略,根据改变复用增益阈值自适应获得最佳DMT与中断性能.数值仿真表明,所提的DMT策略可以逼近协作MIMO的DMT上限,协作节点采用该策略的中断性能仅次于上限的中断性能.在多节点构成协作MIMO网络分布式空时编码协作中,提出的DMT新方案可使系统高效地获得协作分集增益与中断性能.

  16. 2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON

    DEFF Research Database (Denmark)

    Deng, Lei; Pang, Xiaodan; Zhao, Ying;

    2012-01-01

    -based zero forcing (ZF) channel estimation algorithm is designed to compensate the polarization rotation and wireless multipath fading. A 797 Mb/s net data rate QPSK-OFDM signal with error free (<1 × 10-5) performance and a 1.59 Gb/s net data rate 16QAM-OFDM signal with BER performance of 1.2 × 10-2 are...

  17. Spatial Modulation- Spatial Multiplexing in Massive MIMO

    OpenAIRE

    Murthy, Garimella Rama; Sankhe, Kunal

    2016-01-01

    Massive MIMO, a candidate for 5G technology, promises significant gains in wireless data rates and link reliability by using large numbers of antennas (more than 64) at the base transceiver station (BTS). Extra antennas help by focusing the transmission and reception of signal energy into ever-smaller regions of space. This brings huge improvements in throughput. However, it requires a large number of Radio Frequency (RF) chains (usually equal to number of transmit antennas), which is a major...

  18. Adaptive Channel Estimation based on Soft Information Processing in Broadband Spatial Multiplexing Receivers

    Directory of Open Access Journals (Sweden)

    P. Beinschob

    2010-11-01

    Full Text Available In this paper we present a novel approach in Multiple-Input Multiple Output (MIMO Orthogonal Frequency Division Multiplexing (OFDM channel estimation technique based on a Decision Directed Recursive Least Squares (RLS algorithm in which no pilot symbols need to be integrated in the data after a short initial preamble. The novelty and key concept of the proposed technique is the block-wise causal and anti-causal RLS processing that yields two independent processings of RLS along with the associated decisions. Due to the usage of low density parity check (LDPC channel code, the receiver operates with soft information, which enables us to introduce a new modification of the Turbo principle as well as a simple information combining approach based on approximated aposteriori log-likelihood ratios (LLRs. Although the computational complexity is increased by both of our approaches, the latter is relatively less complex than the former. Simulation results show that these implementations outperform the simple RLS-DDCE algorithm and yield lower bit error rates (BER and more accurate channel estimates.

  19. Distributed MIMO radar using compressive sampling

    CERN Document Server

    Petropulu, Athina P; Poor, H Vincent

    2009-01-01

    A distributed MIMO radar is considered, in which the transmit and receive antennas belong to nodes of a small scale wireless network. The transmit waveforms could be uncorrelated, or correlated in order to achieve a desirable beampattern. The concept of compressive sampling is employed at the receive nodes in order to perform direction of arrival (DOA) estimation. According to the theory of compressive sampling, a signal that is sparse in some domain can be recovered based on far fewer samples than required by the Nyquist sampling theorem. The DOAs of targets form a sparse vector in the angle space, and therefore, compressive sampling can be applied for DOA estimation. The proposed approach achieves the superior resolution of MIMO radar with far fewer samples than other approaches. This is particularly useful in a distributed scenario, in which the results at each receive node need to be transmitted to a fusion center.

  20. BER Analysis of MIMO-OFDM System using BPSK Modulation Scheme

    OpenAIRE

    Shruti Trivedi; Mohd. Sarwar Raeen; Shalendra Singh pawar

    2012-01-01

    Multiple transmit and receive can be used to form multiple-input multiple-output (MIMO) channels to increase the capacity and data rate. The key advantage of employing multiple antennas is to get reliable performance through diversity and the achievable higher data rate through spatial multiplexing. In MIMO system the some information can transmitted and received from multiple antennas simultaneously since the fading for each link between a pair of transmit and receive antennas can usually be...

  1. Baseband Processing in Analog Combining MIMO Systems: From Theoretical Design to FPGA Implementation

    OpenAIRE

    Elvira Arregui, Víctor

    2011-01-01

    In this thesis, we consider an analog antenna combining architecture for a MIMO wireless transceiver, while pointing out its advantages with respect to the traditional MIMO architectures. In the first part of this work, we focus on the transceiver design, especially the calculation of the beamformers that must be applied at the RF. This analysis is performed in an OFDM system under different assumptions on the channel state information. As a result, several criteria and algorithms for the sel...

  2. Physical Layer Security for Massive MIMO: An Overview on Passive Eavesdropping and Active Attacks

    OpenAIRE

    Kapetanovic, Dzevdan; Zheng, Gan; Rusek, Fredrik

    2015-01-01

    This article discusses opportunities and challenges of physical layer security integration in massive multiple-input multiple-output (MaMIMO) systems. Specifically, we first show that MaMIMO itself is robust against passive eavesdropping attacks. We then review a pilot contamination scheme which actively attacks the channel estimation process. This pilot contamination attack is not only dramatically reducing the achievable secrecy capacity but is also difficult to detect. We proceed by review...

  3. MimoSA: a system for minimotif annotation

    Directory of Open Access Journals (Sweden)

    Kundeti Vamsi

    2010-06-01

    Full Text Available Abstract Background Minimotifs are short peptide sequences within one protein, which are recognized by other proteins or molecules. While there are now several minimotif databases, they are incomplete. There are reports of many minimotifs in the primary literature, which have yet to be annotated, while entirely novel minimotifs continue to be published on a weekly basis. Our recently proposed function and sequence syntax for minimotifs enables us to build a general tool that will facilitate structured annotation and management of minimotif data from the biomedical literature. Results We have built the MimoSA application for minimotif annotation. The application supports management of the Minimotif Miner database, literature tracking, and annotation of new minimotifs. MimoSA enables the visualization, organization, selection and editing functions of minimotifs and their attributes in the MnM database. For the literature components, Mimosa provides paper status tracking and scoring of papers for annotation through a freely available machine learning approach, which is based on word correlation. The paper scoring algorithm is also available as a separate program, TextMine. Form-driven annotation of minimotif attributes enables entry of new minimotifs into the MnM database. Several supporting features increase the efficiency of annotation. The layered architecture of MimoSA allows for extensibility by separating the functions of paper scoring, minimotif visualization, and database management. MimoSA is readily adaptable to other annotation efforts that manually curate literature into a MySQL database. Conclusions MimoSA is an extensible application that facilitates minimotif annotation and integrates with the Minimotif Miner database. We have built MimoSA as an application that integrates dynamic abstract scoring with a high performance relational model of minimotif syntax. MimoSA's TextMine, an efficient paper-scoring algorithm, can be used to

  4. Relay Techniques for MIMO Wireless Networks with Multiple Source and Destination Pairs

    Directory of Open Access Journals (Sweden)

    Shi Hui

    2006-01-01

    Full Text Available A multiple-input multiple-output (MIMO relay network comprises source, relay, and destination nodes, each of which is equipped with multiple antennas. In a previous work, we proposed a MIMO relay scheme for a relay network with a single source and destination pair in which each of the multiple relay nodes performs QR decompositions of the backward and forward channel matrices in conjunction with phase control (QR-P-QR. In this paper, we extend this scheme to a MIMO relay network employing multiple source and destination pairs. Towards this goal, we use a group nulling approach to decompose a multiple S-D MIMO relay channel into parallel independent S-D MIMO relay channels, and then apply the QR-P-QR scheme to each of the decomposed MIMO relay links. We analytically show the logarithmic capacity scaling of the proposed relay scheme. Numerical examples confirm that the proposed relay scheme offers higher capacity than existing relay schemes.

  5. Performance of MIMO-OFDM system using Linear Maximum Likelihood Alamouti Decoder

    Directory of Open Access Journals (Sweden)

    Monika Aggarwal

    2012-06-01

    Full Text Available A MIMO-OFDM wireless communication system is a combination of MIMO and OFDM Technology. The combination of MIMO and OFDM produces a powerful technique for providing high data rates over frequency-selective fading channels. MIMO-OFDM system has been currently recognized as one of the most competitive technology for 4G mobile wireless systems. MIMO-OFDM system can compensate for the lacks of MIMO systems and give play to the advantages of OFDM system.In this paper , the bit error rate (BER performance using linear maximum likelihood alamouti combiner (LMLAC decoding technique for space time frequency block codes(STFBC MIMO-OFDM system with frequency offset (FO is being evaluated to provide the system with low complexity and maximum diversity. The simulation results showed that the scheme has the ability to reduce ICI effectively with a low decoding complexity and maximum diversity in terms of bandwidth efficiency and also in the bit error rate (BER performance especially at high signal to noise ratio.

  6. Distributed User Selection in Network MIMO Systems with Limited Feedback

    KAUST Repository

    Elkhalil, Khalil

    2015-09-06

    We propose a distributed user selection strategy in a network MIMO setting with M base stations serving K users. Each base station is equipped with L antennas, where LM ≪ K. The conventional selection strategy is based on a well known technique called semi-orthogonal user selection when the zero-forcing beamforming (ZFBF) is adopted. Such technique, however, requires perfect channel state information at the transmitter (CSIT), which might not be available or need large feedback overhead. This paper proposes an alternative distributed user selection technique where each user sets a timer that is inversely proportional to his channel quality indicator (CQI), as a means to reduce the feedback overhead. The proposed strategy allows only the user with the highest CQI to respond with a feedback. Such technique, however, remains collision free only if the transmission time is shorter than the difference between the strongest user timer and the second strongest user timer. To overcome the situation of longer transmission times, the paper proposes another feedback strategy that is based on the theory of compressive sensing, where collision is allowed and all users encode their feedback information and send it back to the base-stations simultaneously. The paper shows that the problem can be formulated as a block sparse recovery problem which is agnostic on the transmission time, which makes it a good alternative to the timer approach when collision is dominant.

  7. Algebraic and Adaptive MIMO Radar

    OpenAIRE

    Morency, Matthew

    2015-01-01

    Breaking causality is the main distinction of the multiple-input multiple-output (MIMO) paradigm as used for active sensing/radar. This is because the transmitting side can be optimized in many ways to manipulate the capabilities of the system. Adaptive beamforming is a fundamental problem in array-processing, communications, and radar among other fields which has once again garnered significant research interest in recent years within the MIMO paradigm. In this work, transmit adaptive beamfo...

  8. Shannon information capacity of time reversal wideband multiple-input multiple-output system based on correlated statistical channels

    Science.gov (United States)

    Yu, Yang; Bing-Zhong, Wang; Shuai, Ding

    2016-05-01

    Utilizing channel reciprocity, time reversal (TR) technique increases the signal-to-noise ratio (SNR) at the receiver with very low transmitter complexity in complex multipath environment. Present research works about TR multiple-input multiple-output (MIMO) communication all focus on the system implementation and network building. The aim of this work is to analyze the influence of antenna coupling on the capacity of wideband TR MIMO system, which is a realistic question in designing a practical communication system. It turns out that antenna coupling stabilizes the capacity in a small variation range with statistical wideband channel response. Meanwhile, antenna coupling only causes a slight detriment to the channel capacity in a wideband TR MIMO system. Comparatively, uncorrelated stochastic channels without coupling exhibit a wider range of random capacity distribution which greatly depends on the statistical channel. The conclusions drawn from information difference entropy theory provide a guideline for designing better high-performance wideband TR MIMO communication systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61331007, 61361166008, and 61401065) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120185130001).

  9. Capacity of fully correlated MIMO system using character expansion of groups

    Directory of Open Access Journals (Sweden)

    Ejaz Khan

    2005-09-01

    Full Text Available It is well known that the use of antenna arrays at both sides of communication link can result in high channel capacities provided that the propagation medium is rich scattering. In most previous works presented on MIMO wireless structures, Rayleigh fading conditions were considered. In this work, the capacity of MIMO systems under fully correlated (i.e., correlations between rows and columns of channel matrix fading is considered. We use replica method and character expansions to calculate the capacity of correlated MIMO channel in closed form. In our calculations, it is assumed that the receiver has perfect channel state information (CSI but no such information is available at the transmitter.

  10. Fast Implementation of Transmit Beamforming for Colocated MIMO Radar

    Directory of Open Access Journals (Sweden)

    G. V. K. Sharma

    2015-04-01

    Full Text Available Multiple-input Multiple-output (MIMO radars benefit from spatial and waveform diversities to improve the performance potential. Phased array radars transmit scaled versions of a single waveform thereby limiting the transmit degrees of freedom to one. However MIMO radars transmit diverse waveforms from different transmit array elements thereby increasing the degrees of freedom to form flexible transmit beampatterns. The transmit beampattern of a colocated MIMO radar depends on the zero-lag correlation matrix of different transmit waveforms. Many solutions have been developed for designing the signal correlation matrix to achieve a desired transmit beampattern based on optimization algorithms in the literature. In this paper, a fast algorithm for designing the correlation matrix of the transmit waveforms is developed that allows the next generation radars to form flexible beampatterns in real-time. An efficient method for sidelobe control with negligible increase in mainlobe width is also presented.

  11. Active fault detection in MIMO systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2014-01-01

    from auxiliary input to residual outputs. The analysis is based on a singular value decomposition of these transfer functions Based on this analysis, it is possible to design auxiliary input as well as design of the associated residual vector with respect to every single parametric fault in the system......The focus in this paper is on active fault detection (AFD) for MIMO systems with parametric faults. The problem of design of auxiliary inputs with respect to detection of parametric faults is investigated. An analysis of the design of auxiliary inputs is given based on analytic transfer functions...

  12. Distributed Joint Cluster Formation and Resource Allocation Scheme for Cooperative Data Collection in Virtual MIMO-Based M2M Networks

    Directory of Open Access Journals (Sweden)

    Xi Luan

    2015-01-01

    Full Text Available An efficient data collection scheme plays an important role for the real-time intelligent monitoring in many machine-to-machine (M2M networks. In this paper, a distributed joint cluster formation and resource allocation scheme for data collection in cluster-based M2M networks is proposed. Specifically, in order to utilize the advantages of cooperation, we first propose a hierarchical transmission model which contains two communication phases. In the first phase, the intracluster information sharing is carried out by all the nodes within the same cluster. Then these nodes transmit the total information to the BS cooperatively with virtual-MIMO (VMIMO protocol in the second phase. To grasp the properties and advantages of this cooperative transmission strategy, the theoretical analysis results are provided. The key issue in this system is to form the clusters and allocate resources efficiently. Since the optimization problem on this issue is an NP-hard problem, a feasible joint scheme for the cluster formation and resource allocation is proposed in this paper, which is carried out via coalition formation game with a distributed algorithm. This scheme can reduce the complexity while keeping an attractive performance. Simulation results show the properties of the proposed scheme and its advantages when comparing with the noncooperative scheme for the data collection in a practical scenario.

  13. Assessment of capacity support and scattering in experimental high speed vehicle to vehicle MIMO links

    DEFF Research Database (Denmark)

    Eggers, Patrick Claus F.; Brown, Tim; Olesen, Kim; Pedersen, Gert Frølund

    2007-01-01

    Preliminary results on the use of the vehicle to vehicle MIMO channel in a rural highway environment are presented. This is looked at both in terms of the available spatial multiplexing through singular value decomposition and also angular distribution within the channel. Results indicate a stron...

  14. A survey of Performance Analysis in MIMO - OFDM Systems

    OpenAIRE

    Jitendra Kumar Daksh; Ravi Mohan; Sumit Sharma

    2013-01-01

    This paper is devoted to space-time coding for multiple-input/multiple-output (MIMO) systems. The concept of space-time coding is explained in a systematic way. The performance of space-time codes for wireless multiple-antenna systems with and without channel state information (CSI) at the transmitter has been also studied. We also study about the number of antennas, the higher space time coding diversity and the related study with the advantages and disadvantages.

  15. A survey of Performance Analysis in MIMO - OFDM Systems

    Directory of Open Access Journals (Sweden)

    J itendra K umar D aksh

    2013-06-01

    Full Text Available Thispaperis devoted tospace-time coding formultiple-input/multiple-output (MIMO systems.The concept of space-time coding is explainedin asystematic way. The performance of space-timecodes for wireless multiple-antenna systems withand without channel state information (CSI at thetransmitter has been also studied.We also studyabout the number of antennas, the higher spacetime coding diversityand the related study with theadvantages and disadvantages

  16. Computer-based multi-channel analyzer based on internet

    International Nuclear Information System (INIS)

    Combined the technology of Internet with computer-based multi-channel analyzer, a new kind of computer-based multi-channel analyzer system which is based on browser is presented. Its framework and principle as well as its implementation are discussed

  17. Antenna Design for Diversity and MIMO Application

    DEFF Research Database (Denmark)

    Ying, Zhinong; Chiu, Chi-Yuk; Zhao, Kun;

    2015-01-01

    efficiencies of MIMO elements would be degraded severely due to mutual couplings. In addition, the human body causes high losses on electromagnetic waves. In real applications, the presence of users may result in significant reduction of total antenna efficiencies, and the correlations of MIMO antenna systems...... are also highly affected. In this chapter, the performance of some basic MIMO antennas as well as recent technologies toimprove MIMO antenna performance of portable devices and mobile terminals are reviewed. The interactions between MIMO antennas and human body are also addressed particularly in...

  18. IMPLEMENTATION OF MIMO OFDM STF CODING FRAMEWORK FOR WIRELESS COMMUNICATION SYSTEM

    Directory of Open Access Journals (Sweden)

    R VEERANNA

    2010-12-01

    Full Text Available The current problems in wireless systems are multi-path propagation, frequency selective fading, inter-symbol interference and inter-carrier interference. A major challenge being transmission of information having high data rates over long distances. The Orthogonal Frequency Division Multiplexing (OFDM systems solve a few of these problems which are mentioned above. This Paper makes an attempt to simulate Space Time Frequency coded communication system using diversity schemes like MIMO and Multiple Input Single Output (MISO and compares their performances over a fading channel having inherent noise. On simulation in MATLAB 7.0.1, MIMO scheme performed better than MISO in comparison of bit error rates with respect to signal to noise ratios. Paper also compares the channel capacity obtained by various MIMO diversities as function of signal to noise (SNR ratio and proves that as diversity increases the channel apacity increases.

  19. Robust Transceiver with Tomlinson-Harashima Precoding for Amplify-and-Forward MIMO Relaying Systems

    KAUST Repository

    Xing, Chengwen

    2012-09-01

    In this paper, robust transceiver design with Tomlinson-Harashima precoding (THP) for multi-hop amplifyand-forward (AF) multiple-input multiple-output (MIMO) relaying systems is investigated. At source node, THP is adopted to mitigate the spatial intersymbol interference. However, due to its nonlinear nature, THP is very sensitive to channel estimationerrors. In order to reduce the effects of channel estimation errors, a joint Bayesian robust design of THP at source, linear forwarding matrices at relays and linear equalizer at destination is proposed. With novel applications of elegant characteristics of multiplicative convexity and matrix-monotone functions, the optimal structure of the nonlinear transceiver is first derived. Based on the derived structure, the transceiver design problem reduces to a much simpler one with only scalar variables which can be efficiently solved. Finally, the performance advantage of the proposed robust design over non-robust design is demonstrated by simulation results.

  20. Adaptive MIMO-OFDM Scheme with Reduced Computational Complexity and Improved Capacity

    Directory of Open Access Journals (Sweden)

    L. C. Siddanna Gowd

    2011-03-01

    Full Text Available The general multidimensional linear channel model adequately represents a plethora of communication system models which utilize multidimensional transmit-receive signals for attaining increased rates and reliability in the presence of fading. The logarithmic dependence of the spectral efficiency of the transmitted power makes it extremely expensive to increase the capacity solely by radiating more power. Also, increasing the transmitted power in a mobile terminal is not advisable due to possible violation of regulatory power masks and possible electromagnetic radiation effects. Alternately, MIMO schemes if properly exploited can exhibit a linearly increasing capacity, due to the presence of a rich scattering environment that provides independent transmission paths from each transmit to each receive antenna. An Idealized practical communication system assumes perfect channel state information (CSI and uses a linear transmitter to maximize the reliability of the wireless multi-antenna link. However, in actual practice the CSI is incomplete. As a result of this, there is a necessity to deal with ergodic and compound capacity formulations and these factors are strongly dependent on the model utilized to characterize the channel. Practical system models include quasi-static multiple-input multipleoutput (MIMO, MIMO-OFDM, ISI, amplify-andforward (AF, decode-and-forward (DF, and MIMO automatic repeat request (ARQ models. Each of the above models introduces its own structure, its own error performance limits, and its own requirements on coding and decoding schemes. Finding general purpose transceiver structures with (provably good performance in these scenarios, and with a reasonable computational complexity, is challenging. Existing MIMO systems are able to provide either high spectral efficiency (spatial multiplexing or low error rate (high diversity via exploiting multiple degrees of freedom available in the channel, but not both simultaneously as

  1. An Energy-Efficient MIMO Algorithm with Receive Power Constraint

    CERN Document Server

    Glazunov, Andrés Alayón

    2012-01-01

    We consider the energy-efficiency of Multiple-Input Multiple-Output (MIMO) systems with constrained received power rather than constrained transmit power. A Energy-Efficient Water-Filling (EEWF) algorithm that maximizes the ratio of the transmission rate to the total transmit power has been derived. The EEWF power allocation policy establishes a trade-off between the transmission rate and the total transmit power under the total receive power constraint. The static and the uncorrelated fast fading Rayleigh channels have been considered, where the maximization is performed on the instantaneous realization of the channel assuming perfect information at both the transmitter and the receiver with equal number of antennas. We show, based on Monte Carlo simulations that the energy-efficiency provided by the EEWF algorithm can be more than an order of magnitude greater than the energy-efficiency corresponding to capacity achieving Water-Filling (WF) algorithm. We also show that the energy-efficiency increases with b...

  2. Near-ML Signal Detection in Large-Dimension Linear Vector Channels Using Reactive Tabu Search

    CERN Document Server

    Srinidhi, N; Chockalingam, A; Rajan, B Sundar

    2009-01-01

    Low-complexity near-optimal signal detection in large dimensional communication systems is a challenge. In this paper, we present a reactive tabu search (RTS) algorithm, a heuristic based combinatorial optimization technique, to achieve low-complexity near-maximum likelihood (ML) signal detection in linear vector channels with large dimensions. Two practically important large-dimension linear vector channels are considered: i) multiple-input multiple-output (MIMO) channels with large number (tens) of transmit and receive antennas, and ii) severely delay-spread MIMO inter-symbol interference (ISI) channels with large number (tens to hundreds) of multipath components. These channels are of interest because the former offers the benefit of increased spectral efficiency (several tens of bps/Hz) and the latter offers the benefit of high time-diversity orders. Our simulation results show that, while algorithms including variants of sphere decoding do not scale well for large dimensions, the proposed RTS algorithm s...

  3. MAXIMUM LIKELIHOOD SOURCE SEPARATION FOR FINITE IMPULSE RESPONSE MULTIPLE INPUT-MULTIPLE OUTPUT CHANNELS IN THE PRESENCE OF ADDITIVE NOISE

    Institute of Scientific and Technical Information of China (English)

    Kazi Takpaya; Wei Gang

    2003-01-01

    Blind identification-blind equalization for Finite Impulse Response (FIR) Multiple Input-Multiple Output (MIMO) channels can be reformulated as the problem of blind sources separation. It has been shown that blind identification via decorrelating sub-channels method could recover the input sources. The Blind Identification via Decorrelating Sub-channels(BIDS)algorithm first constructs a set of decorrelators, which decorrelate the output signals of subchannels, and then estimates the channel matrix using the transfer functions of the decorrelators and finally recovers the input signal using the estimated channel matrix. In this paper, a new approximation of the input source for FIR-MIMO channels based on the maximum likelihood source separation method is proposed. The proposed method outperforms BIDS in the presence of additive white Gaussian noise.

  4. MAXIMUM LIKELIHOOD SOURCE SEPARATION FOR FINITE IMPULSE RESPONSE MULTIPLE INPUT—MULTIPLE OUTPUT CHANNELS IN THE PRESENCE OF ADDITIVE NOISE

    Institute of Scientific and Technical Information of China (English)

    AaziTakpaya; WeiGang

    2003-01-01

    Blind identification-blind equalization for finite Impulse Response(FIR)Multiple Input-Multiple Output(MIMO)channels can be reformulated as the problem of blind sources separation.It has been shown that blind identification via decorrelating sub-channels method could recover the input sources.The Blind Identification via Decorrelating Sub-channels(BIDS)algorithm first constructs a set of decorrelators,which decorrelate the output signals of subchannels,and then estimates the channel matrix using the transfer functions of the decorrelators and finally recovers the input signal using the estimated channel matrix.In this paper,a new qpproximation of the input source for FIR-MIMO channels based on the maximum likelihood source separation method is proposed.The proposed method outperforms BIDS in the presence of additive white Garssian noise.

  5. Analyses and performance of techniques PAPR reduction for STBC MIMO-OFDM system in (4G) wireless communication

    OpenAIRE

    Leila Sahraoui; Djmail Messadeg; Nouredinne Doghmane

    2013-01-01

    An OFDM system is combined with multiple-input multiple-output (MIMO) in order to increase the diversity gain and system capacity over the time variant frequency-selective channels. However, a major drawback of MIMO-OFDM system is that the transmitted signals on different antennas might exhibit high peak-to-average power ratio (PAPR).In this paper, we present a PAPR analysis reduction of space-timeblock-coded (STBC) MIMO-OFDM system for 4G wirelessnetworks. Several techniques have been used t...

  6. VLSI Design of Pipelined R2MDC FFT for MIMO OFDM Transceivers

    Directory of Open Access Journals (Sweden)

    N. Kirubanandasarathy

    2013-01-01

    Full Text Available In this study, an area-efficient low power FFT (Fast Fourier Transform processor is proposed for MIMO-OFDM (Multi Input Multi Output-Orthogonal Frequency Division Multiplexing that consists of a modified architecture of radix-2 algorithm which is described as Radix-2 Multipath Delay Commutation (R2MDC. Orthogonal frequency-division multiplexing is a popular method for high-data-rate wireless transmission. OFDM may be combined with multiple antennas at both the access point and mobile terminal to increase diversity gain and/or Enhance system capacity on a time-varying multi path fading channel, resulting in a multiple-input multiple-output OFDM system. This study described the VLSI design of R2MDC FFT for high throughput MIMO OFDM transceivers targeted to future wireless LAN systems. The proposed system is pipelined Radix 2 multipath delay commutation FFT has been designed for MIMO OFDM. The MIMO OFDM transceivers have been designed according to the proposed OFDM parameters. A low-power efficient and full-pipelined architecture enables the real-time operations of MIMO OFDM transceivers. The FPGA board has been developed to verify their circuit behavior and implementation of MIMO OFDM Transceivers.

  7. MIMO Underwater Acoustic Communications in Ports and Shallow Waters at Very High Frequency

    Directory of Open Access Journals (Sweden)

    Gaultier Real

    2013-10-01

    Full Text Available Hermes is a Single-Input Single-Output (SISO underwater acoustic modem that achieves very high-bit rate digital communications in ports and shallow waters. Here, the authors study the capability of Hermes to support Multiple-Input-Multiple-Output (MIMO technology. A least-square channel estimation algorithm is used to evaluate multiple MIMO channel impulse responses at the receiver end. A deconvolution routine is used to separate the messages coming from different sources. This paper covers the performance of both the channel estimation and the MIMO deconvolution processes using either simulated data or field data. The MIMO equalization performance is measured by comparing three relative root mean-squared errors (RMSE, obtained by calculations between the source signal (a pseudo-noise sequence and the corresponding received MIMO signal at various stages of the deconvolution process; prior to any interference removal, at the output of the Linear Equalization (LE process and at the output of an interference cancellation process with complete a priori knowledge of the transmitted signal. Using the simulated data, the RMSE using LE is −20.5 dB (where 0 dB corresponds to 100% of relative error while the lower bound value is −33.4 dB. Using experimental data, the LE performance is −3.3 dB and the lower bound RMSE value is −27 dB.

  8. Active Fault Isolation in MIMO Systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2014-01-01

    isolation is based directly on the input/output s ignals applied for the fault detection. It is guaranteed that the fault group includes the fault that had occurred in the system. The second step is individual fault isolation in the fault group . Both types of isolation are obtained by applying dedicated......Active fault isolation of parametric faults in closed-loop MIMO system s are considered in this paper. The fault isolation consists of two steps. T he first step is group- wise fault isolation. Here, a group of faults is isolated from other pos sible faults in the system. The group-wise fault...

  9. Peak-to-Average Power Ratio Reduction in MIMO-OFDM Systems Based on Decomposed Selected Mapping%基于分解选择映射的MIMO-OFDM系统峰均比降低算法

    Institute of Scientific and Technical Information of China (English)

    高静; 汪晋宽; 解志斌

    2009-01-01

    针对多输入多输出正交频分复用(MIMO-OFDM)系统中的高峰均功率比(PAPR)问题,提出了一种新的基于选择映射(SLM)的分解算法.所提算法将每根天线上OFDM 符号的实部和虚部进行分解,然后分别进行相位映射,从而增加了待选信号的数量.利用实序列固有的共轭对称特性,在不增加算法复杂度的前提下,显著提高了算法的峰均比降低性能.同时提出了一种基于并行选择映射的分解算法,进一步减少了边带信息的传输量,提高了系统的频带利用率.仿真实验结果证明,所提算法在保持计算复杂度不变的同时,可以有效的提高峰均比性能.

  10. Modified PTS with FECs for PAPR Reduction in MIMO-OFDM System with Different Subblocks and Subcarriers

    OpenAIRE

    Mukunthan Pandurangan; Dananjayan Perumal

    2011-01-01

    Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) systems have been proposed in the recent past for providing high data-rate services over wireless channels. When combined with space time coding it provides the advantages of space-time coding and OFDM, resulting in a spectrally efficient wideband communication system. However, MIMO OFDM systems suffer with the problem of inherent high peak-to-average power ratio (PAPR) due to the intersymbol interference be...

  11. Broadband Wireless Channel measurements for high speed trains

    OpenAIRE

    Kaltenberger, Florian; BYIRINGIRO, Auguste; Arvanitakis, George; GHADDAB, Ryad; NUSSBAUM, Dominique; Knopp, Raymond; Berbineau, Marion; Cocheril, Yann; Philippe, Henri

    2014-01-01

    We describe a channel sounding measurement campaign for cellular broadband wireless communications with high speed trains that was carried out in the context of the project CORRIDOR. The campaign combines MIMO and carrier aggregation to achieve very highth roughputs. We compare two different scenarios, the first one reflects a cellular deployment, where the base station is about 1 km away from the railway line. The second scenario corresponds to a railway deployed network, where the base stat...

  12. Adaptive reconfigurable V-BLAST type equalizer for cognitive MIMO-OFDM radios

    Science.gov (United States)

    Ozden, Mehmet Tahir

    2015-12-01

    An adaptive channel shortening equalizer design for multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) radio receivers is considered in this presentation. The proposed receiver has desirable features for cognitive and software defined radio implementations. It consists of two sections: MIMO decision feedback equalizer (MIMO-DFE) and adaptive multiple Viterbi detection. In MIMO-DFE section, a complete modified Gram-Schmidt orthogonalization of multichannel input data is accomplished using sequential processing multichannel Givens lattice stages, so that a Vertical Bell Laboratories Layered Space Time (V-BLAST) type MIMO-DFE is realized at the front-end section of the channel shortening equalizer. Matrix operations, a major bottleneck for receiver operations, are accordingly avoided, and only scalar operations are used. A highly modular and regular radio receiver architecture that has a suitable structure for digital signal processing (DSP) chip and field programable gate array (FPGA) implementations, which are important for software defined radio realizations, is achieved. The MIMO-DFE section of the proposed receiver can also be reconfigured for spectrum sensing and positioning functions, which are important tasks for cognitive radio applications. In connection with adaptive multiple Viterbi detection section, a systolic array implementation for each channel is performed so that a receiver architecture with high computational concurrency is attained. The total computational complexity is given in terms of equalizer and desired response filter lengths, alphabet size, and number of antennas. The performance of the proposed receiver is presented for two-channel case by means of mean squared error (MSE) and probability of error evaluations, which are conducted for time-invariant and time-variant channel conditions, orthogonal and nonorthogonal transmissions, and two different modulation schemes.

  13. Channel Norm-Based User Scheduling Exploiting Channel Asymmetry in Base Station Cooperative Transmission Systems

    CERN Document Server

    Han, Shengqian; Bengtsson, Mats

    2010-01-01

    Base station cooperative transmission, which is also known as coordinated multi-point (CoMP) transmission, is a promising technique to improve spectrum efficiency in future cellular systems. However, they need large signalling overhead to gather the channel information. In this paper, we consider low feedback user scheduling in downlink coherent CoMP systems exploiting their inherent channel asymmetry. Through the analysis of the statistics of the angle between channel vectors and the tightness of a lower bound of the orthogonally projected norm, we show that channel norm provides sufficient information to judge the orthogonality among users in asymmetric channels. Based on this observation, we propose a channel norm-based user scheduler (NUS), a local channel aided NUS (LocalNUS) and a large-scale fading-based user scheduler (LUS). Simulation results show that the LocalNUS performs very close to the existing greedy user scheduler (GUS) and semi-orthogonal user scheduler (SUS) with full channel state informat...

  14. Enabling VLSI Processing Blocks for MIMO-OFDM Communications

    Directory of Open Access Journals (Sweden)

    Barbara Cerato

    2008-03-01

    Full Text Available Multi-input multi-output (MIMO systems combined with orthogonal frequency-division multiplexing (OFDM gained a wide popularity in wireless applications due to the potential of providing increased channel capacity and robustness against multipath fading channels. However these advantages come at the cost of a very high processing complexity and the efficient implementation of MIMO-OFDM receivers is today a major research topic. In this paper, efficient architectures are proposed for the hardware implementation of the main building blocks of a MIMO-OFDM receiver. A sphere decoder architecture flexible to different modulation without any loss in BER performance is presented while the proposed matrix factorization implementation allows to achieve the highest throughput specified in the IEEE 802.11n standard. Finally a novel E8 sphere decoder approach is presented, which allows for the realization of new golden space time trellis coded modulation (GST-TCM scheme. Implementation cost and offered throughput are provided for the proposed architectures synthesized on a 0.13 μm CMOS standard cell technology or on advanced FPGA devices.

  15. Multiuser detection algorithm based on belief propagation in multiple-input multiple-output systems

    Institute of Scientific and Technical Information of China (English)

    JIANG Wei; XIANG Haige

    2004-01-01

    In MIMO (multiple-input, multiple-output) systems, signals from different transmitting antennas interfere at each receiving antenna and multiuser detection (MUD)algorithms may be adopted to improve the system performance. This paper proposes a novel multiuser detection algorithm in MIMO systems based on the idea of "belief propagation" which has achieved great accomplishment in decoding of low-density parity-check codes. The proposed algorithm has a low computation complexity proportional to the square of transmitting/receiving antenna number. Simulation results show that under low signal-to-noise ratio (SNR) circumstances, the proposed algorithm outperforms the traditional linear minimum mean square error (MMSE) detector while it encounters a "floor" of bit error rate under high SNR circumstances. So the proposed algorithm is applicable to MIMO systems with channel coding and decoding. Although in this paper the proposed algorithm is derived in MIMO systems, obviously it can be applied to ordinary code-division multiple access (CDMA) systems.

  16. ESTIMATION OF CARRIER FREQUENCY OFFSETS FOR MIMO SYSTEMS WITH DISTRIBUTED TRANSMIT ANTENNAS

    Institute of Scientific and Technical Information of China (English)

    Deng Kai; Tang Youxi; Lei Xia; Li Shaoqian

    2007-01-01

    The problem of estimating the carrier frequency offsets in Multiple-Input Multiple-Output (MIMO) systems with distributed transmit antennas is addressed. It is supposed that the transmit antennas are distributed while the receive antennas are still centralized, and the general case where both the time delays and the frequency offsets are possibly different for each transmit antenna is considered. The channel is supposed to be frequency flat, and the macroscopic fading is also taken into consideration. A carrier frequency offset estimator based on Maximum Likelihood (ML) is proposed,which can separately estimate the frequency offset for each transmit antenna and exploit the spatial diversity. The Cramer-Rao Bound (CRB) for synchronous MIMO (i.e., the time delays for each transmit antenna are all equal) is also derived. Simulation results are given to illustrate the performance of the estimator and compare it with the CRB. It is shown that the estimator can provide satisfactory frequency offset estimates and its performance is close to the CRB for the Signal-to-Noise Ratio (SNR) below 20dB.

  17. Advanced Signal Processing for MIMO-OFDM Receivers

    DEFF Research Database (Denmark)

    Manchón, Carles Navarro

    This thesis deals with a wide range of topics within the research area of advanced baseband receiver design for wireless communication systems. In particular, the work focuses on signal processing algorithms for receivers in multiple-input multiple-output (MIMO) orthogonal frequency......-division multiplexing (OFDM) systems, with a particular emphasis on the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard as a study case. Signal processing in wireless receivers can be designed following different strategies. On the one hand, one can use intuitive argumentation to define...... the applicability of MF methods to the problem of estimation of sparse signals. Among the contributions within the area of heuristic approaches, we highlight our study of iterative MIMO detection, interference cancellation and decoding for LTE systems. A detailed study of channel estimation algorithms for OFDM...

  18. Power efficient low complexity precoding for massive MIMO systems

    KAUST Repository

    Sifaou, Houssem

    2014-12-01

    This work aims at designing a low-complexity precoding technique in the downlink of a large-scale multiple-input multiple-output (MIMO) system in which the base station (BS) is equipped with M antennas to serve K single-antenna user equipments. This is motivated by the high computational complexity required by the widely used zero-forcing or regularized zero-forcing precoding techniques, especially when K grows large. To reduce the computational burden, we adopt a precoding technique based on truncated polynomial expansion (TPE) and make use of the asymptotic analysis to compute the deterministic equivalents of its corresponding signal-to-interference-plus-noise ratios (SINRs) and transmit power. The asymptotic analysis is conducted in the regime in which M and K tend to infinity with the same pace under the assumption that imperfect channel state information is available at the BS. The results are then used to compute the TPE weights that minimize the asymptotic transmit power while meeting a set of target SINR constraints. Numerical simulations are used to validate the theoretical analysis. © 2014 IEEE.

  19. Integrated DWDM and MIMO-OFDM System for 4G High Capacity Mobile Communication System

    Directory of Open Access Journals (Sweden)

    Shikha Nema

    2009-10-01

    Full Text Available Dense wavelength-division multiplexing (DWDM technique is a very promising data transmission technology for utilizing the capacity of the fiber. By DWDM, multiple signals (video, audio, data etc staggered in wavelength domain can be multiplexed and transmitted down the same fiber. The Multiple-input multiple-output (MIMO wireless technology in combination with orthogonal frequency division multiplexing (MIMO-OFDM is an attractive air-interface solution for next-generation wireless local area networks (WLANs and fourth-generation mobile cellular wireless systems. This article provides an overview of the integrated DWDM MIMO-OFDM technology and focuses on DWDM transmitter design with adequate dispersion compensation for high data rate of 10Gbps ,MIMO-OFDM system design, space-time coded signaling, receiver design and performance analysis in terms of bit error rate for Integrated system. The simulation is carried out using powerful software tools Optisystem and MATLAB . In this paper a 64 channel DWDM system is simulated for transmission of baseband NRZ signal over fiber. Each of the transmission is at bit rate of 10 Gbps leading to high data rate transmission of 640 Gbps.The resultant Bit Error Rate(BER is in the range 10-12 for DWDM system which is given as input to MIMO-OFDM system..This system performance is analyzed in terms of BER with SNR for Rayleigh, and AWGN channels and BER of 10-4 is achieved at SNR of 10dbs

  20. Low-Complexity CFO Estimation for Multi-User Massive MIMO Systems

    OpenAIRE

    Mukherjee, Sudarshan; Mohammed, Saif Khan

    2015-01-01

    Low-complexity carrier frequency offset (CFO) estimation and compensation in multi-user massive multiple-input multiple-output (MIMO) systems is a challenging problem. The existing CFO estimation algorithms incur tremendous increase in complexity with increasing number of base station (BS) antennas, $M$ and number of user terminals (UTs) $K$ (i.e. massive MIMO regime). In this paper, we address this problem by proposing a novel low-complexity algorithm for CFO estimation which uses the pilot ...

  1. Properties of the MIMO radar ambiguity function

    OpenAIRE

    Chen, Chun-Yang; Vaidyanathan, P.P.

    2008-01-01

    MIMO (multiple-input multiple-output) radar is an emerging technology which has drawn considerable attention. Unlike the traditional SIMO (single-input multiple-output) radar, which transmits scaled versions of a single waveform in the antenna elements, the MIMO radar transmits independent waveforms in each of the antenna elements. It has been shown that MIMO radar systems have many advantages such as high spatial resolution, improved parameter identifiability, and enhanced flexibility for tr...

  2. MIMO Communication Using Single Feed Antenna Arrays

    DEFF Research Database (Denmark)

    Alrabadi, Osama

    Multi-input-multi-output (MIMO) communication has emerged as a promis- ing technology for meeting the increasing demand on higher data rates. The technology exploits the spatial resource dimension by sending the datas- treams to different locations in the multi element array (MEA) domain while...... prototype. The experiments show that the proposed beamspace MIMO approach provides performance compara- ble to a conventional MIMO system, but at a reduced size and hardware complexity....

  3. Sequential decoders for large MIMO systems

    KAUST Repository

    Ali, Konpal S.

    2014-05-01

    Due to their ability to provide high data rates, multiple-input multiple-output (MIMO) systems have become increasingly popular. Decoding of these systems with acceptable error performance is computationally very demanding. In this paper, we employ the Sequential Decoder using the Fano Algorithm for large MIMO systems. A parameter called the bias is varied to attain different performance-complexity trade-offs. Low values of the bias result in excellent performance but at the expense of high complexity and vice versa for higher bias values. Numerical results are done that show moderate bias values result in a decent performance-complexity trade-off. We also attempt to bound the error by bounding the bias, using the minimum distance of a lattice. The variations in complexity with SNR have an interesting trend that shows room for considerable improvement. Our work is compared against linear decoders (LDs) aided with Element-based Lattice Reduction (ELR) and Complex Lenstra-Lenstra-Lovasz (CLLL) reduction. © 2014 IFIP.

  4. Performance Analysis of Cooperative Virtual MIMO Systems for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Adnan Al-Anbuky

    2013-05-01

    Full Text Available Multi-Input Multi-Output (MIMO techniques can be used to increase the data rate for a given bit error rate (BER and transmission power. Due to the small form factor, energy and processing constraints of wireless sensor nodes, a cooperative Virtual MIMO as opposed to True MIMO system architecture is considered more feasible for wireless sensor network (WSN applications. Virtual MIMO with Vertical-Bell Labs Layered Space-Time (V-BLAST multiplexing architecture has been recently established to enhance WSN performance. In this paper, we further investigate the impact of different modulation techniques, and analyze for the first time, the performance of a cooperative Virtual MIMO system based on V-BLAST architecture with multi-carrier modulation techniques. Through analytical models and simulations using real hardware and environment settings, both communication and processing energy consumptions, BER, spectral efficiency, and total time delay of multiple cooperative nodes each with single antenna are evaluated. The results show that cooperative Virtual-MIMO with Binary Phase Shift Keying-Wavelet based Orthogonal Frequency Division Multiplexing (BPSK-WOFDM modulation is a promising solution for future high data-rate and energy-efficient WSNs.

  5. Resource allocation and MIMO for 4G and beyond

    CERN Document Server

    2014-01-01

    This book presents the underlying technological breakthroughs that allowed the current state of wireless technology development to evolve. The book focuses on the two lower layers of the ISO/OSI layered model, specifically the physical and data link layers including the media access control sub-layer. These two layers are of particular importance to wireless systems due to the spectrum shortage, the broadcast nature of interference, and time variability in the wireless channel. Topics covered in this book include: radio resource allocation (RRA) for emerging architectures such as Coordinated Multipoint (CoMP) and Device-to-Device communications (D2D); RRA for quality of service control; propagation and transceiver aspects of MIMO systems; and the design and selection of MIMO multiuser precoders. The proposed approaches for RRA and MIMO are applicable to mobile communication standards such as 3GPP’s LTE and LTE-Advanced, but also apply further to the continuously evolving wireless access technologies lan...

  6. Zero-Forcing Pre-coding for MIMO WiMAX Transceivers

    DEFF Research Database (Denmark)

    Cattoni, Andrea Fabio; Le Moullec, Yannick; Sacchi, Claudio

    2013-01-01

    able to mitigate the multi-user interference of the MU-MIMO systems in the context of a realistic WiMAX application scenario. Simulation results show that pre-coding can significantly increase the channel capacity. Furthermore, the paper presents several feasibility considerations for implementation of...

  7. Algebraic number theory and code design for Rayleigh fading channels

    CERN Document Server

    Oggier, F

    2014-01-01

    Algebraic number theory is having an increasing impact in code design for many different coding applications, such as single antenna fading channels and more recently, MIMO systems.Extended work has been done on single antenna fading channels, and algebraic lattice codes have been proven to be an effective tool. The general framework has been settled in the last ten years and many explicit code constructions based on algebraic number theory are now available. The aim of this work is to provide both an overview on algebraic lattice code designs for Rayleigh fading channels, as well as a tutoria

  8. CAMAC based 4-channel 12-bit digitizer

    International Nuclear Information System (INIS)

    With the development in Fusion research a large number of diagnostics are being used to understand the complex behaviour of plasma. During discharge, several diagnostics demand high sampling rate and high bit resolution to acquire data for rapid changes in plasma parameters. For the requirements of such fast diagnostics, a 4-channel simultaneous sampling, high-speed, 12-bit CAMAC digitizer has been designed and developed which has several important features for application in CAMAC based nuclear instrumentation. The module has independent ADC per channel for simultaneous sampling and digitization, and 512 Ksamples RAM per channel for on-board storage. The digitizer has been designed for event based acquisition and the acquisition window gives post-trigger as well as pre-trigger (software selectable) data that is useful for analysis. It is a transient digitizer and can be operated either in pre/post trigger mode or in burst mode. The record mode and the active memory size are selected through software commands to satisfy the current application. The module can be used to acquire data at high sampling rate for short time discharge e.g. 512 ms at 1MSPS. The module can also be used for long time discharge at low sampling rate e.g. 512 seconds at 1KSPS. This paper describes the design of digitizer module, development of VHDL code for hardware logic, Graphical User Interface (GUI) and important features of module from application point of view. The digitizer has CPLD based hardware logic, which provides flexibility in configuring the module for different sampling rates and different pre/post trigger samples through GUI. The digitizer can be operated with either internal (for testing/acquisition) or external (synchronized acquisition) clock and trigger. The digitizer has differential inputs with bipolar input range ±5V and it is being used with sampling rate of 1 MSamples Per Second (MSPS) per channel but it also supports higher sampling rate up to 3MSPS per channel. A

  9. Weighted Sum-Rate Maximization Using Weighted MMSE for MIMO-BC Beamforming Design

    DEFF Research Database (Denmark)

    Christensen, Søren; De Carvalho, Elisabeth; Agarwal, Rajiv;

    2009-01-01

    This paper studies linear transmit filter design for weighted sum-rate (WSR) maximization in the multiple input multiple output broadcast channel (MIMO-BC). The problem of finding the optimal transmit filter is non-convex and intractable to solve using low complexity methods. Motivated by recent...... results highlighting the relationship between mutual information and Minimum Mean Square Error (MMSE), this paper establishes a relationship between weighted sum-rate and weighted MMSE in the MIMO-BC. The relationship is used to propose a low complexity algorithm for finding a local weighted sum...

  10. On end-to-end performance of MIMO multiuser in cognitive radio networks

    KAUST Repository

    Yang, Yuli

    2011-12-01

    In this paper, a design for the multiple-input-multiple-output (MIMO) multiuser transmission in the cognitive radio network is developed and its end-to-end performance is investigated under spectrum-sharing constraints. Firstly, the overall average packet error rate is analyzed by considering the channel state information feedback delay and the multiuser scheduling. Then, we provide corresponding numerical results to measure the performance evaluation for several separate scenarios, which presents a convenient tool for the cognitive radio network design with multiple secondary MIMO users. © 2011 IEEE.

  11. Iteration-stopping scheme of turbo receiver in turbo-MIMO systems

    Institute of Scientific and Technical Information of China (English)

    Zheng Jianping; Bai Baoming; Wang Xinmei

    2008-01-01

    The iteration-stopping scheme of turbo receiver, consisting of an inner multiple-input multiple-output (MIMO) detector and an outer turbo decoder, was studied in this paper.In the inner MIMO detector,only the reliabilities of bits in those channel slots which included unreliable information bits were updated when the outer turbo code was a systematical one.In conjunction with the trigger events for stopping the turbo decoding, an iteration-stopping scheme of turbo receiver was proposed.Simulation results show that the proposed scheme has lower complexity, but almost the same error performance compared to the scheme with predetermined maximum iterations.

  12. Signal Processing for Wireless Communication MIMO System with Nano- Scaled CSDG MOSFET based DP4T RF Switch.

    Science.gov (United States)

    Srivastava, Viranjay M

    2015-01-01

    In the present technological expansion, the radio frequency integrated circuits in the wireless communication technologies became useful because of the replacement of increasing number of functions, traditional hardware components by modern digital signal processing. The carrier frequencies used for communication systems, now a day, shifted toward the microwave regime. The signal processing for the multiple inputs multiple output wireless communication system using the Metal- Oxide-Semiconductor Field-Effect-Transistor (MOSFET) has been done a lot. In this research the signal processing with help of nano-scaled Cylindrical Surrounding Double Gate (CSDG) MOSFET by means of Double- Pole Four-Throw Radio-Frequency (DP4T RF) switch, in terms of Insertion loss, Isolation, Reverse isolation and Inter modulation have been analyzed. In addition to this a channel model has been presented. Here, we also discussed some patents relevant to the topic. PMID:25986227

  13. Design of MIMO Space-Time Code for High Data Rate Wireless Communication

    Directory of Open Access Journals (Sweden)

    Mihir Narayan Mohanty,

    2011-02-01

    Full Text Available Multiple-input and multiple-output, or MIMO, is the use of multiple antennas at both the transmitter and receiver to improve communication performance. MIMO technology has attracted attention in wireless communications, because it offers significant increases in data throughput and link range without additional bandwidth or transmit power. In this paper, multiple-input–multiple-output (MIMO systems with reduced complexity is considered. The space–time block coding, for communication over Rayleigh fading channels using multiple transmit antennas is considered. Also the Alamouti code is tested for the performance. Data is encoded using a space–time block code and the encoded data is split into n streams which are simultaneously transmitted using n transmit antennas. The received signal at each receive antenna is a linear superposition of the n transmitted signals perturbed by noise. In current research, high data rate wireless communications, transmission rates, is of major interest. The idea behind MIMO is that the signals on the transmit (Tx antennas at one end and the receive (Rx antennas at the other end are “combined” in such a way that the quality (bit-error rate or BER or the data rate (bits/sec of the communication for each MIMO user will be improved.

  14. 2D MIMO Network Coding with Inter-Route Interference Cancellation

    Science.gov (United States)

    Tran, Gia Khanh; Sakaguchi, Kei; Ono, Fumie; Araki, Kiyomichi

    Infrastructure wireless mesh network has been attracting much attention due to the wide range of its application such as public wireless access, sensor network, etc. In recent years, researchers have shown that significant network throughput gain can be achieved by employing network coding in a wireless environment. For further improvement of network throughput in one dimensional (1D) topology, Ono et al. proposed to use multiple antenna technique combined with network coding. In this paper, being inspired by MIMO network coding in 1D topology, the authors establish a novel MIMO network coding algorithm for a 2D topology consisting of two crossing routes. In this algorithm, multiple network coded flows are spatially multiplexed. Owing to the efficient usage of radio resource of network coding and co-channel interference cancellation ability of MIMO, the proposed algorithm shows an 8-fold gain in network capacity compared to conventional methods in the best-case scenario.

  15. Compensation for HPA nonlinearity and I/Q imbalance in MIMO beamforming systems

    KAUST Repository

    Qi, Jian

    2010-10-01

    In this paper, we investigate the effects of high-power amplifier (HPA) nonlinearity and in-phase and quadrature-phase (I/Q) imbalance on the performance of multiple-input multiple-output (MIMO) transmit beamforming (TB) systems. Specifically, we propose a compensation method for HPA nonlinearity and I/Q imbalance together in MIMO TB systems. The performance of the MIMO TB system under study is evaluated in terms of the average symbol error probability (SEP) and system capacity, considering transmission over uncorrelated frequency-flat Rayleigh fading channels. Numerical results are provided and show the effects of several system parameters, such as the HPA parameters, image-leakage ratio, numbers of transmit and receive antennas, length of pilot symbols, and modulation order of phase-shift keying (PSK), on performance. © 2010 IEEE.

  16. Computation of antenna pattern correlation and MIMO performance by means of surface current distribution and spherical wave theory

    Directory of Open Access Journals (Sweden)

    O. Klemp

    2006-01-01

    Full Text Available In order to satisfy the stringent demand for an accurate prediction of MIMO channel capacity and diversity performance in wireless communications, more effective and suitable models that account for real antenna radiation behavior have to be taken into account. One of the main challenges is the accurate modeling of antenna correlation that is directly related to the amount of channel capacity or diversity gain which might be achieved in multi element antenna configurations. Therefore spherical wave theory in electromagnetics is a well known technique to express antenna far fields by means of a compact field expansion with a reduced number of unknowns that was recently applied to derive an analytical approach in the computation of antenna pattern correlation. In this paper we present a novel and efficient computational technique to determine antenna pattern correlation based on the evaluation of the surface current distribution by means of a spherical mode expansion.

  17. Constrained Optimization of MIMO Training Sequences

    Directory of Open Access Journals (Sweden)

    Coon Justin P

    2007-01-01

    Full Text Available Multiple-input multiple-output (MIMO systems have shown a huge potential for increased spectral efficiency and throughput. With an increasing number of transmitting antennas comes the burden of providing training for channel estimation for coherent detection. In some special cases optimal, in the sense of mean-squared error (MSE, training sequences have been designed. However, in many practical systems it is not feasible to analytically find optimal solutions and numerical techniques must be used. In this paper, two systems (unique word (UW single carrier and OFDM with nulled subcarriers are considered and a method of designing near-optimal training sequences using nonlinear optimization techniques is proposed. In particular, interior-point (IP algorithms such as the barrier method are discussed. Although the two systems seem unrelated, the cost function, which is the MSE of the channel estimate, is shown to be effectively the same for each scenario. Also, additional constraints, such as peak-to-average power ratio (PAPR, are considered and shown to be easily included in the optimization process. Numerical examples illustrate the effectiveness of the designed training sequences, both in terms of MSE and bit-error rate (BER.

  18. Feedback of channel state information in multi-antenna systems based on quantization of channel Gram matrices

    OpenAIRE

    Sacristán Murga, Daniel Francisco

    2012-01-01

    This dissertation deals with the proper design of efficient feedback strategies for Multiple-Input Multiple-Output (MIMO) communication systems. MIMO systems outperform single antenna systems in terms of achievable throughput and are more resilient to noise and interference, which are becoming the limiting factors in the current and future communications. Apart from the clear performance advantages, MIMO systems introduce an additional complexity factor, since they require knowledge of the pr...

  19. MIMO Precoding in Underlay Cognitive Radio Systems with Completely Unknown Primary CSI

    CERN Document Server

    Mukherjee, Amitav; Swindlehurst, A Lee

    2012-01-01

    This paper studies a novel underlay MIMO cognitive radio (CR) system, where the instantaneous or statistical channel state information (CSI) of the interfering channels to the primary receivers (PRs) is completely unknown to the CR. For the single underlay receiver scenario, we assume a minimum information rate must be guaranteed on the CR main channel whose CSI is known at the CR transmitter. We first show that low-rank CR interference is preferable for improving the throughput of the PRs compared with spreading less power over more transmit dimensions. Based on this observation, we then propose a rank minimization CR transmission strategy assuming a minimum information rate must be guaranteed on the CR main channel. We propose a simple solution referred to as frugal waterfilling (FWF) that uses the least amount of power required to achieve the rate constraint with a minimum-rank transmit covariance matrix. We also present two heuristic approaches that have been used in prior work to transform rank minimizat...

  20. Robust image transmission over MIMO space-time coded wireless systems

    Science.gov (United States)

    Song, Daewon; Chen, Chang W.

    2006-05-01

    We present in this paper an integrated robust image transmission scheme using space-time block codes (STBC) over multi-input multi-output (MIMO) wireless systems. First, in order to achieve an excellent error resilient capability, multiple bitstreams are generated based on wavelet trees along the spatial orientations. The spatial-orientation trees in the wavelet domain are individually encoded using SPIHT. Error propagation is thus limited within each bitstreams. Then, Reed-Solomon (R-S) codes as forward error correction (FEC) are adopted to combat transmission errors over error-prone wireless channels and to detect residual errors so as to avoid error propagation in each bitstream. FEC can reduce the bit error rates at the expenses of increased data rate. However, it is often difficult to design an optimal FEC scheme for a time-varying multi-path fading channel that may fluctuate beyond the capacity of the adopted FEC scheme. Therefore, in order to overcome such difficulty, we propose an approach to alleviate the effect of multi-path fading by employing the STBC for spatial diversity with assumption that channel state information (CSI) is perfectly estimated at the receiver. Experimental results demonstrate that the proposed scheme can achieve much improved performance in terms of PSNR over Rayleigh flat fading channel as compared with a wireless system without spatial diversity.

  1. Scintillation detectors based on silicon microfluidic channels

    International Nuclear Information System (INIS)

    Microfluidic channels obtained by SU-8 photolithography and filled with liquid scintillators were recently demonstrated to be an interesting technology for the implementation of novel particle detectors. The main advantages of this approach are the intrinsic radiation resistance resulting from the simple microfluidic circulation of the active medium and the possibility to manufacture devices with high spatial resolution and low material budget using microfabrication techniques. Here we explore a different technological implementation of this concept, reporting on scintillating detectors based on silicon microfluidic channels. A process for manufacturing microfluidic devices on silicon substrates, featuring microchannel arrays suitable for light guiding, was developed. Such process can be in principle combined with standard CMOS processing and lead to a tight integration with the readout photodetectors and electronics in the future. Several devices were manufactured, featuring microchannel geometries differing in depth, width and pitch. A preliminary characterization of the prototypes was performed by means of a photomultiplier tube coupled to the microchannel ends, in order to detect the scintillation light produced upon irradiation with beta particles from a 90Sr source. The photoelectron spectra thus obtained were fitted with the expected output function in order to extract the light yield

  2. Scintillation detectors based on silicon microfluidic channels

    Science.gov (United States)

    Maoddi, P.; Mapelli, A.; Bagiacchi, P.; Gorini, B.; Haguenauer, M.; Lehmann Miotto, G.; Murillo Garcia, R.; Safai Tehrani, F.; Veneziano, S.; Renaud, P.

    2014-01-01

    Microfluidic channels obtained by SU-8 photolithography and filled with liquid scintillators were recently demonstrated to be an interesting technology for the implementation of novel particle detectors. The main advantages of this approach are the intrinsic radiation resistance resulting from the simple microfluidic circulation of the active medium and the possibility to manufacture devices with high spatial resolution and low material budget using microfabrication techniques. Here we explore a different technological implementation of this concept, reporting on scintillating detectors based on silicon microfluidic channels. A process for manufacturing microfluidic devices on silicon substrates, featuring microchannel arrays suitable for light guiding, was developed. Such process can be in principle combined with standard CMOS processing and lead to a tight integration with the readout photodetectors and electronics in the future. Several devices were manufactured, featuring microchannel geometries differing in depth, width and pitch. A preliminary characterization of the prototypes was performed by means of a photomultiplier tube coupled to the microchannel ends, in order to detect the scintillation light produced upon irradiation with beta particles from a 90Sr source. The photoelectron spectra thus obtained were fitted with the expected output function in order to extract the light yield.

  3. OUTPUT FEEDBACK CONTROL FOR MIMO NONLINEAR SYSTEMS WITH EXOGENOUS SIGNALS

    Institute of Scientific and Technical Information of China (English)

    Ying ZHOU; Yuqiang WU

    2006-01-01

    The paper addresses the global output tracking of a class of multi-input multi-output(MIMO) nonlinear systems affected by disturbances, which are generated by a known exosystem. An adaptive controller is designed based on the proposed observer and the backstepping approach to asymptotically track arbitrary reference signal and to guarantee the boundedness of all the signals in the closed loop system. Finally, the numerical simulation results illustrate the effectiveness of the proposed scheme.

  4. A Channelization-Based DOA Estimation Method for Wideband Signals

    Directory of Open Access Journals (Sweden)

    Rui Guo

    2016-07-01

    Full Text Available In this paper, we propose a novel direction of arrival (DOA estimation method for wideband signals with sensor arrays. The proposed method splits the wideband array output into multiple frequency sub-channels and estimates the signal parameters using a digital channelization receiver. Based on the output sub-channels, a channelization-based incoherent signal subspace method (Channelization-ISM and a channelization-based test of orthogonality of projected subspaces method (Channelization-TOPS are proposed. Channelization-ISM applies narrowband signal subspace methods on each sub-channel independently. Then the arithmetic mean or geometric mean of the estimated DOAs from each sub-channel gives the final result. Channelization-TOPS measures the orthogonality between the signal and the noise subspaces of the output sub-channels to estimate DOAs. The proposed channelization-based method isolates signals in different bandwidths reasonably and improves the output SNR. It outperforms the conventional ISM and TOPS methods on estimation accuracy and dynamic range, especially in real environments. Besides, the parallel processing architecture makes it easy to implement on hardware. A wideband digital array radar (DAR using direct wideband radio frequency (RF digitization is presented. Experiments carried out in a microwave anechoic chamber with the wideband DAR are presented to demonstrate the performance. The results verify the effectiveness of the proposed method.

  5. A Channelization-Based DOA Estimation Method for Wideband Signals.

    Science.gov (United States)

    Guo, Rui; Zhang, Yue; Lin, Qianqiang; Chen, Zengping

    2016-01-01

    In this paper, we propose a novel direction of arrival (DOA) estimation method for wideband signals with sensor arrays. The proposed method splits the wideband array output into multiple frequency sub-channels and estimates the signal parameters using a digital channelization receiver. Based on the output sub-channels, a channelization-based incoherent signal subspace method (Channelization-ISM) and a channelization-based test of orthogonality of projected subspaces method (Channelization-TOPS) are proposed. Channelization-ISM applies narrowband signal subspace methods on each sub-channel independently. Then the arithmetic mean or geometric mean of the estimated DOAs from each sub-channel gives the final result. Channelization-TOPS measures the orthogonality between the signal and the noise subspaces of the output sub-channels to estimate DOAs. The proposed channelization-based method isolates signals in different bandwidths reasonably and improves the output SNR. It outperforms the conventional ISM and TOPS methods on estimation accuracy and dynamic range, especially in real environments. Besides, the parallel processing architecture makes it easy to implement on hardware. A wideband digital array radar (DAR) using direct wideband radio frequency (RF) digitization is presented. Experiments carried out in a microwave anechoic chamber with the wideband DAR are presented to demonstrate the performance. The results verify the effectiveness of the proposed method. PMID:27384566

  6. Design and Verification of MIMO 2x2 Reference Antennas

    DEFF Research Database (Denmark)

    Szini, Istvan Janos; Pedersen, Gert Frølund; Estrada, J.; Scannavini, A.; Foged, L. J.

    The development and initial discussion of a reference MIMO 2×2 antenna concept has been presented in [1]. The reference antenna concept has been created to eliminate the uncertainties linked to the unknown antenna performance of the few LTE MIMO 2×2 reference devices or golden standards currently...... available for evaluating radiated data throughput measurement methodologies and test facilities. The proposed concept is based on simple antennas with a well-known Figure of Merit (FoM) and controllable performance. In this paper we present the recent developments on the antenna concept and report on the...... first measured performance at uniform incoming power distribution, figures and correlations between different measurement labs....

  7. Downlink scheduling of multiuser MIMO systems with transmit beamforming

    Institute of Scientific and Technical Information of China (English)

    SONG Xing-hua; WU Wei-ling

    2008-01-01

    This article deals with downlink scheduling for multiuser multiple-input multiple-output (MIMO) systems, where the base station communicates with multiple users simultaneously through transmit beamforming. Most of the existing transmission schemes for multiuser MIMO systems focus on optimizing sum rate performance of the system. The individual quality of service (QoS) requirements (such as packet delay and minimum transmission rate for the data traffic) are rarely considered. In this article, a novel scheduling strategy is proposed, where we try to optimize the global system performance under individual QoS constraints. By performing scheduling into two steps, namely successive user selection and power allocation, the scheduler can achieve efficient resource utilization while maintaining the QoS requirements of all users. Extensive simulations and analysis are given to show the effectiveness of the proposed scheduler.

  8. Cognitive MIMO Frequency Diverse Array Radar with High LPI Performance

    Directory of Open Access Journals (Sweden)

    Ling Huang

    2016-01-01

    Full Text Available Frequency diverse array (FDA has its unique advantage in realizing low probability of intercept (LPI technology for its dependent beam pattern. In this paper, we proposed a cognitive radar based on the frequency diverse array multiple-input multiple-output (MIMO. To implement LPI of FDA MIMO transmit signals, a scheme for array weighting design is proposed, which is to minimize the energy of the target location and maximize the energy of the receiver. This is based on the range dependent characteristics of the frequency diverse array transmit beam pattern. To realize the objective problem, the algorithm is proposed as follows: the second-order nonconvex optimization problem is converted into a convex problem and solved by the bisection method and convex optimization. To get the information of target, the FDA MIMO radar is proposed to estimate the target parameters. Simulation results show that the proposed approach is effective in decreasing the detection probability of radar with lossless detection performance of the receive signal.

  9. MIMO over ESPAR with 16-QAM Modulation

    DEFF Research Database (Denmark)

    Han, Bo; Barousis, V.I.; Papadias, C.B.; Kalis, A.; Prasad, Ramjee

    2013-01-01

    MIMO systems have become an indispensable part of modern wireless standards, e.g. LTE advanced. However, in applications with strict energy and size constraints, an alternative MIMO scheme with reduced hardware complexity would be attractive. Towards this direction, parasitic antennas with a single...... feeding port have been proposed to emulate MIMO transmission with PSK signaling. In order to support higher order constellations, this letter presents a smart loading scheme that enables the multiplexing of two 16-QAM signals over the air. Accompanying simulations show that this can be achieved by using a...

  10. Image content authentication based on channel coding

    Science.gov (United States)

    Zhang, Fan; Xu, Lei

    2008-03-01

    The content authentication determines whether an image has been tampered or not, and if necessary, locate malicious alterations made on the image. Authentication on a still image or a video are motivated by recipient's interest, and its principle is that a receiver must be able to identify the source of this document reliably. Several techniques and concepts based on data hiding or steganography designed as a means for the image authentication. This paper presents a color image authentication algorithm based on convolution coding. The high bits of color digital image are coded by the convolution codes for the tamper detection and localization. The authentication messages are hidden in the low bits of image in order to keep the invisibility of authentication. All communications channels are subject to errors introduced because of additive Gaussian noise in their environment. Data perturbations cannot be eliminated but their effect can be minimized by the use of Forward Error Correction (FEC) techniques in the transmitted data stream and decoders in the receiving system that detect and correct bits in error. This paper presents a color image authentication algorithm based on convolution coding. The message of each pixel is convolution encoded with the encoder. After the process of parity check and block interleaving, the redundant bits are embedded in the image offset. The tamper can be detected and restored need not accessing the original image.

  11. MAX-SLNR Precoding Algorithm for Massive MIMO System

    Directory of Open Access Journals (Sweden)

    Jiang Jing

    2016-01-01

    Full Text Available Pilot Contamination obviously degrades the system performance of Massive MIMO systems. In this paper, a downlink precoding algorithm based on the Signal-to- Leakage-plus-Noise-Ratio (SLNR criterion is put forward. First, the impact of Pilot Contamination on SLNR is analyzed,then the precoding matrix is calculated with the eigenvalues decomposition of SLNR, which not only maximize the array gains of the target user, but also minimize the impact of Pilot Contamination and the leak to the users of other cells. Further, a simplified solution is derived, in which the impact of Pilot Contamination can be suppressed only with the large-scale fading coefficients. Simulation results reveal that: in the scenario of the serious pilot contamination, the proposed algorithm can avoid the performance loss caused by the pilot contamination compared with the conventional Massive MIMO precoding algorithm. Thus the proposed algorithm can acquire the perfect performance gains of Massive MIMO system and has better practical value since the large-scale fading coefficients are easy to measure and feedback.

  12. A High-Speed Four-Transmitter Four-Receiver MIMO OFDM Testbed: Experimental Results and Analyses

    Directory of Open Access Journals (Sweden)

    Walkenhorst Brett

    2006-01-01

    Full Text Available By adopting multiple-input multiple-output (MIMO and orthogonal frequency-division multiplexing (OFDM technologies, indoor wireless systems could reach data rates up to several hundreds of Mbits/s and achieve spectral efficiencies of several tens of bits/Hz/s, which are unattainable for conventional single-input single-output systems. The enhancements of data rate and spectral efficiency come from the fact that MIMO and OFDM schemes are indeed parallel transmission technologies in the space and frequency domains, respectively. To validate the functionality and feasibility of MIMO and OFDM technologies, we set up a four-transmitter four-receiver OFDM testbed in a typical indoor environment, which achieves a peak data rate of 525 Mbits/s and a spectral efficiency of 19.2 bits/Hz/s. The performances including MIMO channel characteristics, bit-error rate against signal-to-noise ratio curves, the impairments of carrier frequency offset and channel estimation inaccuracy, and an asymmetric MIMO scheme are reported and analyzed in this paper.

  13. Novel Robust Optimization and Power Allocation of Time Reversal-MIMO-UWB Systems in an Imperfect CSI

    Directory of Open Access Journals (Sweden)

    Sajjad Alizadeh

    2013-03-01

    Full Text Available Time Reversal (TR technique is an attractive solution for a scenario where the transmission system employs low complexity receivers with multiple antennas at both transmitter and receiver sides. The TR technique can be combined with a high data rate MIMO-UWB system as TR-MIMO-UWB system. In spite of TR's good performance in MIMO-UWB systems, it suffers from performance degradation in an imperfect Channel State Information (CSI case. In this paper, at first a robust TR pre-filter is designed together with a MMSE equalizer in TR-MIMO-UWB system where is robust against channel imperfection conditions. We show that the robust pre-filter optimization technique, considerably improves the BER performance of TR-MIMO-UWB system in imperfect CSI, where temporal focusing of the TR technique is kept, especially for high SNR values. Then, in order to improve the system performance more than ever, a power loading scheme is developed by minimizing the average symbol error rate in an imperfect CSI. Numerical and simulation results are presented to confirm the performance advantage attained by the proposed robust optimization and power loading in an imperfect CSI scenario.

  14. Mobile radio channels

    CERN Document Server

    Pätzold, Matthias

    2011-01-01

    Providing a comprehensive overview of the modelling, analysis and simulation of mobile radio channels, this book gives a detailed understanding of fundamental issues and examines state-of-the-art techniques in mobile radio channel modelling. It analyses several mobile fading channels, including terrestrial and satellite flat-fading channels, various types of wideband channels and advanced MIMO channels, providing a fundamental understanding of the issues currently being investigated in the field. Important classes of narrowband, wideband, and space-time wireless channels are explored in deta

  15. Time-Slotted Multiuser MIMO Systems: Beamforming and Scheduling Strategies

    Directory of Open Access Journals (Sweden)

    Serbetli Semih

    2004-01-01

    Full Text Available We investigate the problem of scheduling for the uplink of a time-slotted multiuser multiple-input multiple-output (MIMO system with sum capacity as the performance metric. We first consider scheduling users' transmissions for fixed transmit beamformers. Upper bounds for the sum capacity of the time-slotted system with the optimum scheduler are found via relaxing a set of structural constraints. Next, we present a low-complexity scheduling algorithm that aims to approach the capacity's upper bound. The performance of the multislot multiuser MIMO system is a function of the users' transmit beamformers. In turn, the transmit beamformers can be shaped depending on the channel state information available at the transmitter. We investigate how the transmit beamformers should be chosen with different levels of feedback, and combine the proposed scheduling algorithm with antenna selection, eigen transmit beamforming, and perfectly controlled transmit beamforming models. We observe that as the available feedback level is increased, the performance of the scheduling algorithm approaches the upper bounds developed. In particular, a substantial sum capacity gain is attained when the individual channel state information is available at the transmitter side.

  16. Diversity-Multiplexing Tradeoff via Asymptotic Analysis of Large MIMO Systems

    CERN Document Server

    Loyka, Sergey

    2007-01-01

    Diversity-multiplexing tradeoff (DMT) presents a compact framework to compare various MIMO systems and channels in terms of the two main advantages they provide (i.e. high data rate and/or low error rate). This tradeoff was characterized asymptotically (SNR-> infinity) for i.i.d. Rayleigh fading channel by Zheng and Tse [1]. The asymptotic DMT overestimates the finite-SNR one [2]. In this paper, using the recent results on the asymptotic (in the number of antennas) outage capacity distribution, we derive and analyze the finite-SNR DMT for a broad class of channels (not necessarily Rayleigh fading). Based on this, we give the convergence conditions for the asymptotic DMT to be approached by the finite-SNR one. The multiplexing gain definition is shown to affect critically the convergence point: when the multiplexing gain is defined via the mean (ergodic) capacity, the convergence takes place at realistic SNR values. Furthermore, in this case the diversity gain can also be used to estimate the outage probabilit...

  17. Diversity of MIMO Linear Precoding

    CERN Document Server

    Mehana, Ahmed Hesham

    2012-01-01

    Linear precoding is a relatively simple method of MIMO signaling that can also be optimal in certain special cases. This paper is dedicated to high-SNR analysis of MIMO linear precoding. The Diversity-Multiplexing Tradeoff (DMT) of a number of linear precoders is analyzed. Furthermore, since the diversity at finite rate (also known as the fixed-rate regime, corresponding to multiplexing gain of zero) does not always follow from the DMT, linear precoders are also analyzed for their diversity at fixed rates. In several cases, the diversity at multiplexing gain of zero is found not to be unique, but rather to depend on spectral efficiency. The analysis includes the zero-forcing (ZF), regularized ZF, matched filtering and Wiener filtering precoders. We calculate the DMT of ZF precoding under two common design approaches, namely maximizing the throughput and minimizing the transmit power. It is shown that regularized ZF (RZF) or Matched filter (MF) suffer from error floors for all positive multiplexing gains. Howe...

  18. Radar's LPI Analysis and Application Based on MIMO System%基于MIMO体制的雷达LPI性能分析和应用

    Institute of Scientific and Technical Information of China (English)

    张杰

    2007-01-01

    多输入多输出(MIMO, multiple-input multiple-out)系统在发射端和接收端均采用了多天线技术,利用间隔一定距离的阵元信号之间的独立性和目标闪烁特性提高探测的性能.在介绍MIMO原理的基础上,分析了将MIMO技术应用于实现低截获概率(LPI, low probability of intercept)雷达辐射功率的有效控制,以提高雷达的作战性能和战场生存能力.

  19. Capacity estimation of HF-MIMO systems.

    OpenAIRE

    N. Abbasi; Gunashekar, S.D.; Warrington, E. M.; Salous, S.; Feeney, S. M.; L. Bertel; Lemur, D.; Oger, M.

    2009-01-01

    Multiple input multiple output (MIMO) systems utilize multiple antennas at both the transmitter and the receiver. This paper describes some recent experimental work that has been carried out in order to investigate the feasibility of applying MIMO techniques within the high frequency (HF) band. It is a significant development because the potential increase in data rates will benefit not only the existing HF radio systems but also open this band to new low cost communication applications. The ...

  20. Reduction of PAPR and Efficient detection ordering scheme for MIMO Transmission Systems Using Power Control

    Directory of Open Access Journals (Sweden)

    V.Sreevani

    2015-12-01

    Full Text Available The technical challenges for communication engineers is the development of best performance wireless networks with negligible amount of distortions. We have to consider multipath propagation attenuation and radio spectrum inefficiency. Now a days, In MIMO (Multi Input Multi Output systems there is a huge demand for the networks with the high transmission rates and better quality of service which are having low PAPR ratio. Instead of OFDMA, filter banks are used in massive MIMO to reduce the complexity. But they are error prone to noise. This base paper discusses about PAPR reduction in MIMO systems using different precoding based OFDM systems. Mainly, minimization of multi-antenna systems by controlling the transmission power and reduction of PAPR using ZC (Zadoff-Chu matrix transform.