Downlink SINR Distribution of Linearly Precoded Multiuser MIMO Systems
DEFF Research Database (Denmark)
Lin, Zihuai; Sørensen, Troels Bundgaard; Mogensen, Preben
2007-01-01
This paper derives mathematical expressions for the SINR distribution in systems with linearly precoded multiuser MIMO and frequency domain packet scheduling. The packet scheduler is able to exploit the available multiuser diversity in both time, frequency and spatial domains. Our analysis model...... is confined to 3GPP downlink transmission in which we specifically investigate the Single User (SU) and Multi-user (MU) Spatial Divsion Multiplexing (SDM) MIMO schemes. From the analytical results we find that the outage probability for systems using the SU-MIMO scheme is larger than the one for the MU......-MIMO scheme. Also, in comparison to systems without precoding, linear precoding can improve the outage probability....
LINEAR-DISPERSION DIVISION MULTIPLE-ACCESS FOR MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
Deng Dan; Lv Xingzai; Zhu Jinkang
2008-01-01
Comprehensive study on novel Linear-Dispersion Division Multiple-Access (LDDMA) for multi-user uplink Multiple-Input Multiple-Output (MIMO) systems is proposed. In the new multi- plexing scheme, each user's information symbol is dispersed by a User-Specific Matrix (USM) both in space and time domain and linearly combined at base-station side. And a simple random search al- gorithm, based on capacity maximization criteria, is developed to generate a bank of USMs. Simulation results are presented to demonstrate the advantages of LDDMA. When the Bit Error Rate (BER) reaches 10, the performance gains are 3dB and 5dB, compared with Time-Division Linear Dispersion Codes (TD-LDC) and BLAST, respectively.
Linear Precoding Performance of Massive MU-MIMO downlink System
Pakdeejit, Eakkamol
2013-01-01
Nowadays, multiuser Multiple-In Multiple-Out systems (MU-MIMO) are used in a new generation wireless technologies. Due to that wireless technology improvement is ongoing, the numbers of users and applications increase rapidly. Then, wireless communications need the high data rate and link reliability at the same time. Therefore, MU-MIMO improvements have to consider 1) providing the high data rate and link reliability, 2) support all users in the same time and frequency resource, and 3) using...
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.
New variable structure control for MIMO nonlinear system based on I/O linearization
Institute of Scientific and Technical Information of China (English)
许春山; 孙兴进; 曹广益
2004-01-01
A novel variable structure control (VSC) with new rapid-smooth reaching law (RSRL) and new rapid-convergent sliding mode (FCSM) is proposed, which is based on analysis of normal VSC system. When it is used for an MIMO nonlinear system, we combine the method of Input/Output linearizing (I/O L) with VSC. After analyzing the robustness of the MIMO nonlinear system, we use this novel controller for Precision One Robot position control system. Simulation provides a quite satisfactory performance with uncertainties and external disturbances.
Spatial Frequency Scheduling for Uplink SC-FDMA based Linearly Precoded LTE Multiuser MIMO Systems
DEFF Research Database (Denmark)
Lin, Zihuai; Xiao, Pei; Sørensen, Troels Bundgaard;
2010-01-01
This paper investigates the performance of the 3GPP Long Term Evolution (LTE) uplink Single Carrier (SC) Frequency Division Multiple Access (FDMA) based linearly precoded multiuserMultiple InputMultiple Output (MIMO) systems with frequency domain packet scheduling. A mathematical expression...
Tranceiver Design using Linear Precoding in a Multiuser MIMO System with Limited Feedback
Islam, Muhammad Nazmul
2010-01-01
We investigate quantization and feedback of channel state information in a multiuser (MU) multiple input multiple output (MIMO) system. Each user may receive multiple data streams. Our design minimizes the sum mean squared error (SMSE) while accounting for the imperfections in channel state information (CSI) at the transmitter. This paper makes three contributions: first, we provide an end-to-end SMSE transceiver design that incorporates receiver combining, feedback policy and transmit precoder design with channel uncertainty. This enables the proposed transceiver to outperform the previously derived limited feedback MU linear transceivers. Second, we remove dimensionality constraints on the MIMO system, for the scenario with multiple data streams per user, using a combination of maximum expected signal combining (MESC) and minimum MSE receiver. This makes the feedback of each user independent of the others and the resulting feedback overhead scales linearly with the number of data streams instead of the numb...
Frequency-domain L2-stability conditions for time-varying linear and nonlinear MIMO systems
Institute of Scientific and Technical Information of China (English)
Zhihong HUANG; Y. V. VENKATESH; Cheng XIANG; Tong Heng LEE
2014-01-01
The paper deals with the L2-stability analysis of multi-input-multi-output (MIMO) systems, governed by integral equations, with a matrix of periodic/aperiodic time-varying gains and a vector of monotone, non-monotone and quasi-monotone nonlin-earities. For nonlinear MIMO systems that are described by differential equations, most of the literature on stability is based on an application of quadratic forms as Lyapunov-function candidates. In contrast, a non-Lyapunov framework is employed here to derive new and more general L2-stability conditions in the frequency domain. These conditions have the following features:i) They are expressed in terms of the positive definiteness of the real part of matrices involving the transfer function of the linear time-invariant block and a matrix multiplier function that incorporates the minimax properties of the time-varying linear/nonlinear block. ii) For certain cases of the periodic time-varying gain, they contain, depending on the multiplier function chosen, no restrictions on the normalized rate of variation of the time-varying gain, but, for other periodic/aperiodic time-varying gains, they do. Overall, even when specialized to periodic-coefficient linear and nonlinear MIMO systems, the stability conditions are distinct from and less restrictive than recent results in the literature. No comparable results exist in the literature for aperiodic time-varying gains. Furthermore, some new stability results concerning the dwell-time problem and time-varying gain switching in linear and nonlinear MIMO systems with periodic/aperiodic matrix gains are also presented. Examples are given to illustrate a few of the stability theorems.
H2-optimal approximation of MIMO linear dynamical systems
Van Dooren, Paul; Absil, P -A
2008-01-01
We consider the problem of approximating a multiple-input multiple-output (MIMO) $p\\times m$ rational transfer function $H(s)$ of high degree by another $p\\times m$ rational transfer function $\\hat H(s)$ of much smaller degree, so that the ${\\cal H}_2$ norm of the approximation error is minimized. We characterize the stationary points of the ${\\cal H}_2$ norm of the approximation error by tangential interpolation conditions and also extend these results to the discrete-time case. We analyze whether it is reasonable to assume that lower-order models can always be approximated arbitrarily closely by imposing only first-order interpolation conditions. Finally, we analyze the ${\\cal H}_2$ norm of the approximation error for a simple case in order to illustrate the complexity of the minimization problem.
A Selfish Linear Precoding Strategy for Downlink Two-User MIMO Systems Using Limited Rate Feedback
Directory of Open Access Journals (Sweden)
Lei Lv
2013-07-01
Full Text Available This letter proposes a limited feedback-based selfish linear precoding (SLP strategy for downlink two-user MIMO systems. In the proposed strategy, each user selfishly chooses the other user’s precoding matrix which minimizes its capacity loss. The proposed SLP strategy has two advantages comparing with traditional linear precoding strategies. First, SLP improves the system capacity by resisting interference more effectively. Second, the computing complexity of transmitter is reduced since the base station needs not to calculate precoding matrix. Simulation results verify the effectiveness of SLP on system capacity improvement comparing to limited feedback block diagonalization (LFBD algorithm, especially when feedback bits are insufficient.
Efficient linear precoding for massive MIMO systems using truncated polynomial expansion
Muller, Axel; Kammoun, Abla; Bjornson, Emil; Debbah, Merouane
2014-01-01
International audience; —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" regu-larized 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 ba...
Massive MU-MIMO Downlink TDD Systems with Linear Precoding and Downlink Pilots
Ngo, Hien Quoc; Larsson, Erik G.; Marzetta, Thomas L.
2013-01-01
We consider a massive MU-MIMO downlink time-division duplex system where a base station (BS) equipped with many antennas serves several single-antenna users in the same time-frequency resource. We assume that the BS uses linear precoding for the transmission. To reliably decode the signals transmitted from the BS, each user should have an estimate of its channel. In this work, we consider an efficient channel estimation scheme to acquire CSI at each user, called beamforming training scheme. W...
Robust Linear Transceiver Design for Multi-Hop Non-Regenerative MIMO Relaying Systems
Xing, Chengwen; Ma, Shaodan; Kuang, Jingming; Wu, Yik-Chung
2011-01-01
In this paper, optimal linear transceiver designs for multi-hop amplify-and-forward (AF) Multiple-input Multiple-out (MIMO) relaying systems with Gaussian distributed channel estimation errors are investigated. Some commonly used transceiver design criteria are unified into a single matrix-variate optimization problem. With novel applications of majorization theory and properties of matrix-variate function, the optimal structure of robust transceiver is first derived. Based on the optimal structure, the original transceiver design problems are reduced to much simpler problems with only scalar variables whose solutions are readily obtained by iterative water-filling algorithms. The performance advantages of the proposed robust designs are demonstrated by the simulation results.
Diversity of MIMO Linear Precoding
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...
On the ?2-stability of time-varying linear and nonlinear discrete-time MIMO systems
Institute of Scientific and Technical Information of China (English)
Y.V.VENKATESH
2014-01-01
New conditions are derived for the 2-stability of time-varying linear and nonlinear discrete-time multiple-input multiple-output (MIMO) systems, having a linear time time-invariant block with the transfer function Γ(z), in negative feedback with a matrix of periodic/aperiodic gains A(k),k =0,1,2,. . . and a vector of certain classes of non-monotone/monotone nonlinearitiesϕ( · ), without restrictions on their slopes and also not requiring path-independence of their line integrals. The stability conditions, which are derived in the frequency domain, have the following features: i) They involve the positive definiteness of the real part (as evaluated on |z| = 1) of the product of Γ(z) and a matrix multiplier function of z. ii) For periodic A(k), one class of multiplier functions can be chosen so as to impose no constraint on the rate of variations A(k), but for aperiodic A(k), which allows a more general multiplier function, constraints are imposed on certain global averages of the generalized eigenvalues of (A(k+1),A(k)),k=1,2,. . . . iii) They are distinct from and less restrictive than recent results in the literature.
Comparative Study of Controllers for a Variable Area MIMO Interacting NonLinear System
Directory of Open Access Journals (Sweden)
Priya Chandrasekar
2014-03-01
Full Text Available Most of the industrial processes are basically Multi Input Multi Output (MIMO system. In this paper a new combination of Spherical Conical Interacting Tank System (SCITS which is a variable area nonlinear MIMO system is considered for study and various control algorithms based on Ziegler Nichol’s tuning method, Hagglund Astrom Robust tuning method, Fractional Order (FO control and Passivity Based Control (PBC are used and compared for the level control of spherical tank system and conical tank system connected with interaction. Transfer function matrix of the system is obtained experimentally from the open loop response of the system. The designed controllers are tested for servo and regulatory operations. The controllers are compared in terms of time domain specification and performance index criterion. From the analysis of the simulation results, it is seen that FO controller gives improved performance when compared to conventional Integer Order (IO controller and overall Passivity Based Controller (PBCr gives improved performance comparatively for spherical conical interacting MIMO system.
Efficient linear precoding for massive MIMO systems using truncated polynomial expansion
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.
Joint Linear Filter Design in Multiuser Cooperative Nonregenerative MIMO Relay Systems
Directory of Open Access Journals (Sweden)
Li Gen
2009-01-01
Full Text Available This paper addresses the filter design issues for multiuser cooperative nonregenerative MIMO relay systems in both downlink and uplink scenarios. Based on the formulated signal model, the filter matrix optimization is first performed for direct path and relay path respectively, aiming to minimize the mean squared error (MSE. To be more specific, for the relay path, we derive the local optimal filter scheme at the base station and the relay station jointly in the downlink scenario along with a more practical suboptimal scheme, and then a closed-form joint local optimal solution in the uplink scenario is exploited. Furthermore, the optimal filter for the direct path is also presented by using the exiting results of conventional MIMO link. After that, several schemes are proposed for cooperative scenario to combine the signals from both paths. Numerical results show that the proposed schemes can reduce the bit error rate (BER significantly.
Achievable Rates of MIMO Systems with Linear Precoding and Iterative LMMSE Detection
Yuan, Xiaojun; Kavcic, Aleksandar
2011-01-01
We extend the area property on an additive-white-Gaussian-noise (AWGN) channel to more general linear channel models (including inter-symbol-interference (ISI) and multiple-input multiple-output (MIMO) channels) with arbitrary input constellations. We show that the theoretical limit of a generic linear channel (i.e., the input output mutual information) can be achieved using iterative minimum mean-square error (MMSE) detection under the so-called uniform and Gaussian (UG) assumption on the messages generated in iterative detection. Our major contribution is a linear precoding (LP) technique that can asymptotically ensure the UG assumption as the transmission block length tends to infinity based on the central limit theorem. We also show that superposition coded modulation (SCM) can further help to materialize the UG assumption. Numerical results are demonstrated to verify our analysis.
Massive MIMO Systems: Signal Processing Challenges and Research Trends
de Lamare, R.C.
2013-01-01
This article presents a tutorial on multiuser multiple-antenna wireless systems with a very large number of antennas, known as massive multi-input multi-output (MIMO) systems. Signal processing challenges and future trends in the area of massive MIMO systems are presented and key application scenarios are detailed. A linear algebra approach is considered for the description of the system and data models of massive MIMO architectures. The operational requirements of massive MIMO systems are di...
DEFF Research Database (Denmark)
Rahman, Imadur Mohamed; Marchetti, Nicola; Fitzek, Frank;
2005-01-01
In this work, we have analyzed a joint spatial diversity and multiplexing transmission structure for MIMO-OFDM system, where Orthogonal Space-Frequency Block Coding (OSFBC) is used across all spatial multiplexing branches. We have derived a BLAST-like non-linear Successive Interference Cancellation...... in this paper. We have found that a linear two-stage receiver for the proposed system [1] performs very close to the non-linear receiver studied in this work. Finally, we compared the system performance in spatially correlated scenario. It is found that higher amount of spatial correlation at the transmitter...... (SIC) receiver where the detection is done on subcarrier by sub-carrier basis based on both Zero Forcing (ZF) and Minimum Mean Square Error (MMSE) nulling criterion for the system. In terms of Frame Error Rate (FER), MMSE based SIC receiver performs better than all other receivers compared...
Xing, Chengwen; Ma, Shaodan; Kuang, Jingming; Wu, Yik-Chung
2011-01-01
In this paper, optimal linear transceiver designs for multi-hop amplify-and-forward (AF) Multiple-input Multiple-out (MIMO) relaying systems with Gaussian distributed channel estimation errors are investigated. Some commonly used transceiver design criteria such as weighted mean-square-error (MSE) minimization, mutual information maximization, worst MSE/MAX-MSE minimization and weighted sum-rate maximization, are taken into a single matrix-variate optimization problem. Exploiting majorization theory and properties of matrix-variate functions, the optimal structures of robust transceivers are derived. Based on the optimal structures, the original transceiver design problems are reduced to much simpler problems with only scalar variables whose solutions are readily obtained by iterative water-filling algorithms. A number of existing transceiver design algorithms are found to be special cases of the proposed solution. The performance advantages of the proposed robust designs are demonstrated by the simulation re...
Stable Inversion of MIMO Linear Discrete Time Non-Minimum Phase Systems
George, Koshy; Verhaegen, Michel; Scherpen, Jacquelien M.A.
1999-01-01
A novel technique to achieve output tracking via stable inversion of non-minimum phase linear systems is presented wherein the desired signal is obtained from field measurements, and hence corrupted by noise. The earlier approach to stable inversion does not take into account the noise in the system
A General Robust Linear Transceiver Design for Multi-Hop Amplify-and-Forward MIMO Relaying Systems
Xing, Chengwen; Ma, Shaodan; Fei, Zesong; Wu, Yik-Chung; Poor, H. Vincent
2013-03-01
In this paper, linear transceiver design for multi-hop amplify-and-forward (AF) multiple-input multiple-out (MIMO) relaying systems with Gaussian distributed channel estimation errors is investigated. Commonly used transceiver design criteria including weighted mean-square-error (MSE) minimization, capacity maximization, worst-MSE/MAX-MSE minimization and weighted sum-rate maximization, are considered and unified into a single matrix-variate optimization problem. A general robust design algorithm is proposed to solve the unified problem. Specifically, by exploiting majorization theory and properties of matrix-variate functions, the optimal structure of the robust transceiver is derived when either the covariance matrix of channel estimation errors seen from the transmitter side or the corresponding covariance matrix seen from the receiver side is proportional to an identity matrix. Based on the optimal structure, the original transceiver design problems are reduced to much simpler problems with only scalar variables whose solutions are readily obtained by iterative water-filling algorithm. A number of existing transceiver design algorithms are found to be special cases of the proposed solution. The differences between our work and the existing related work are also discussed in detail. The performance advantages of the proposed robust designs are demonstrated by simulation results.
Comparison of Linear Precoding Schemes for the Massive MIMO Downlink
Hoydis, Jakob; Ten Brink, Stephan; Debbah, Mérouane
2012-01-01
978-1-4577-2052-9; International audience; We consider the downlink of a time-division duplexing (TDD) multicell multiuser MIMO system where the base stations (BSs) are equipped with a very large number of antennas. Assuming channel estimation through uplink pilots, arbitrary antenna correlation and user distributions, we derive approximations of achievable rates with linear precoding techniques, namely eigenbeamforming (BF) and regularized zero-forcing (RZF). The approximations are tight in ...
Directory of Open Access Journals (Sweden)
Lin Shao
2016-01-01
Full Text Available Due to large numbers of antennas and users, matrix inversion is complicated in linear precoding techniques for massive MIMO systems. Several approximated matrix inversion methods, including the Neumann series, have been proposed to reduce the complexity. However, the Neumann series does not converge fast enough. In this paper, to speed up convergence, a new joint Newton iteration and Neumann series method is proposed, with the first iteration result of Newton iteration method being employed to reconstruct the Neumann series. Then, a high probability convergence condition is established, which can offer useful guidelines for practical massive MIMO systems. Finally, simulation examples are given to demonstrate that the new joint Newton iteration and Neumann series method has a faster convergence rate compared to the previous Neumann series, with almost no increase in complexity when the iteration number is greater than or equal to 2.
MIMO Identical Eigenmode Transmission System (IETS) - A Channel Decomposition Perspective
Shakir, M Zeeshan
2010-01-01
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 data transmission at higher rate. The system based on such decomposition technique is referred to as MIMO Identical Eigenmode Transmission System (IETS). The comparative analysis of the MIMO transceiver design exploiting nonlinear and linear decomposition techniques for variable constellation is presented in this paper. The new transmission strategy is tested in combination with the Vertical Bell Labs Layered Space Time (V-BLAST) decoding scheme using different number of antennas on both sides of the communication link. The ...
Beyond Multiplexing Gain in Large MIMO Systems
DEFF Research Database (Denmark)
Cakmak, Burak; Müller, Ralf R.; Fleury, Bernard Henri
Given the common technical assumptions in the literature on MIMO channel modeling, we derive generic results for MIMO systems in the large system limit LSL. Consider a $\\ phi T\\ times T $ MIMO system with $ T $ tending to infinity. By increasing the antenna ratio $\\ phi $ when $\\ phi\\ geq 1$, the...
Beyond Multiplexing Gain in Large MIMO Systems
DEFF Research Database (Denmark)
Cakmak, Burak; Müller, Ralf R.; Fleury, Bernard Henri
Given the common technical assumptions in the literature on MIMO channel modeling, we derive generic results for MIMO systems in the large system limit LSL. Consider a $\\ phi T\\ times T $ MIMO system with $ T $ tending to infinity. By increasing the antenna ratio $\\ phi $ when $\\ phi\\ geq 1$, the...
Institute of Scientific and Technical Information of China (English)
XIAO Zheng-rong; ZHAO Shao-gang; WU Wei-ling
2004-01-01
Discrete Fourier Transform (DFT) based multiple-input multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is the focus of wireless communication, which uses cyclic prefixes to reduce the ISI. To improve the spectrum efficiency and system performance, Complex Wavelet Packet Transform (CWPT) based OFDM is used to realize the MIMO-OFDM system. For the good property of complex wavelet packet function, the CWPT based MIMO-OFDM system is better than the DFT based MIMO-OFDM system, but the CWPT based MIMO-OFDM scheme has some additional complexity, and simulation results show that the new system can improve the system performance.
Gregorio, Fernando; Cousseau, Juan; Werner, Stefan; Riihonen, Taneli; Wichman, Risto
2011-12-01
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.
Broadbeam for Massive MIMO Systems
Qiao, Deli; Qian, Haifeng; Li, Geoffrey Ye
2016-05-01
Massive MIMO has been identified as one of the promising disruptive air interface techniques to address the huge capacity requirement demanded by 5G wireless communications. For practical deployment of such systems, the control message need to be broadcast to all users reliably in the cell using broadbeam. A broadbeam is expected to have the same radiated power in all directions to cover users in any place in a cell. In this paper, we will show that there is no perfect broadbeam. Therefore, we develop a method for generating broadbeam that can allow tiny fluctuations in radiated power. Overall, this can serve as an ingredient for practical deployment of the massive MIMO systems.
Multiple-Input Multiple-Output (MIMO Linear Systems Extreme Inputs/Outputs
Directory of Open Access Journals (Sweden)
David O. Smallwood
2007-01-01
Full Text Available A linear structure is excited at multiple points with a stationary normal random process. The response of the structure is measured at multiple outputs. If the autospectral densities of the inputs are specified, the phase relationships between the inputs are derived that will minimize or maximize the trace of the autospectral density matrix of the outputs. If the autospectral densities of the outputs are specified, the phase relationships between the outputs that will minimize or maximize the trace of the input autospectral density matrix are derived. It is shown that other phase relationships and ordinary coherence less than one will result in a trace intermediate between these extremes. Least favorable response and some classes of critical response are special cases of the development. It is shown that the derivation for stationary random waveforms can also be applied to nonstationary random, transients, and deterministic waveforms.
Multimedia over massive MIMO wireless systems
Wang, Haichao; Ge, Xiaohu; Zi, Ran; Zhang, Jing; Ni, Qiang
2015-01-01
To satisfy the massive wireless traffic transmission generated by multimedia applications, the massive multi-input-multi-output (MIMO) wireless system has emerged as a possible solution for future 5G wireless communication systems. However, the mutual coupling effect of massive MIMO systems has a negative effect potential on the wireless capacity. In this paper, the receive diversity gain is first defined and analyzed for massive MIMO wireless systems. Furthermore, we propose an effective cap...
DEFF Research Database (Denmark)
Duplicy, Jonathan; Badic, Biljana; Balraj, Rajarajan;
2011-01-01
A relatively recent idea of extending the benefits of MIMO systems to multi-user scenarios seems promising in the context of achieving high data rates envisioned for future cellular standards after 3G (3rd Generation). Although substantial research has been done on the theoretical front, recent...... for LTE Release 8 are provided. Interestingly, it is shown that MU-MIMO only offers marginal performance gains with respect to singleuser MIMO. This arises from the limited MU-MIMO features included in Release 8 and calls for improved schemes for the upcoming releases....
Ultra Low Complexity Soft Output Detector for Non-Binary LDPC Coded Large MIMO Systems
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.
Networked MIMO with Clustered Linear Precoding
Zhang, Jun; Andrews, Jeffrey G; Ghosh, Arunabha; Heath, Robert W
2008-01-01
A clustered base transceiver station (BTS) coordination strategy is proposed for a large cellular MIMO network, which includes full intra-cluster coordination to enhance the sum rate and limited inter-cluster coordination to reduce interference for the cluster edge users. Multi-cell block diagonalization is used to coordinate the transmissions across multiple BTSs in the same cluster. To satisfy per-BTS power constraints, three combined precoder and power allocation algorithms are proposed with different performance and complexity tradeoffs. For inter-cluster coordination, the coordination area is chosen to balance fairness for edge users and the achievable sum rate. It is shown that a small cluster size (about 7 cells) is sufficient to obtain most of the sum rate benefits from clustered coordination while greatly relieving channel feedback requirement. Simulations show that the proposed coordination strategy efficiently reduces interference and provides a considerable sum rate gain for cellular MIMO networks...
Energy efficient downlink MIMO transmission with linear precoding
Institute of Scientific and Technical Information of China (English)
XU Jie; LI ShiChao; QIU Ling; SLIMANE Ben S.; YU ChengWen
2013-01-01
Energy efficiency （EE） is becoming increasingly important for wireless cellular networks. This paper addresses EE optimization problems in downlink multiuser MIMO systems with linear precoding. Referring to different active transmit/receive antenna sets and transmission schemes as different modes, we propose a joint bandwidth/power optimization and mode switching scheme to maximize EE. With a specific mode, we prove that the optimal bandwidth and transmit power is either full transmit power or full bandwidth. After deriving the optimal bandwidth and transmit power, we further propose mode switching to select the mode with optimal EE. Since the optimal mode switching, i.e. exhaustive search, is too complex to implement, an alternative heuristic method is developed to decrease the complexity through reducing the search size and avoiding the EE calculation during each search. Through simulations, we demonstrate that the proposed methods can significantly improve EE and the performance is similar to the optimal exhaustive search.
Sequential decoders for large MIMO systems
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.
Linear precoding based on polynomial expansion: reducing complexity in massive MIMO
Mueller, Axel; Kammoun, Abla; Björnson, Emil; Debbah, Merouane
2016-01-01
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-opt...
The relative degree enhancement problem for MIMO nonlinear systems
Energy Technology Data Exchange (ETDEWEB)
Schoenwald, D.A. [Oak Ridge National Lab., TN (United States); Oezguener, Ue. [Ohio State Univ., Columbus, OH (United States). Dept. of Electrical Engineering
1995-07-01
The authors present a result for linearizing a nonlinear MIMO system by employing partial feedback - feedback at all but one input-output channel such that the SISO feedback linearization problem is solvable at the remaining input-output channel. The partial feedback effectively enhances the relative degree at the open input-output channel provided the feedback functions are chosen to satisfy relative degree requirements. The method is useful for nonlinear systems that are not feedback linearizable in a MIMO sense. Several examples are presented to show how these feedback functions can be computed. This strategy can be combined with decentralized observers for a completely decentralized feedback linearization result for at least one input-output channel.
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...
Asymptotic Performance of Linear Receivers in MIMO Fading Channels
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...
Callier, Frank M.; Desoer, Charles A.
1991-01-01
The aim of this book is to provide a systematic and rigorous access to the main topics of linear state-space system theory in both the continuous-time case and the discrete-time case; and the I/O description of linear systems. The main thrusts of the work are the analysis of system descriptions and derivations of their properties, LQ-optimal control, state feedback and state estimation, and MIMO unity-feedback systems.
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.
Performance Comparisons of MIMO Techniques with Application to WCDMA Systems
Directory of Open Access Journals (Sweden)
Li Chuxiang
2004-01-01
Full Text Available Multiple-input multiple-output (MIMO communication techniques have received great attention and gained significant development in recent years. In this paper, we analyze and compare the performances of different MIMO techniques. In particular, we compare the performance of three MIMO methods, namely, BLAST, STBC, and linear precoding/decoding. We provide both an analytical performance analysis in terms of the average receiver and simulation results in terms of the BER. Moreover, the applications of MIMO techniques in WCDMA systems are also considered in this study. Specifically, a subspace tracking algorithm and a quantized feedback scheme are introduced into the system to simplify implementation of the beamforming scheme. It is seen that the BLAST scheme can achieve the best performance in the high data rate transmission scenario; the beamforming scheme has better performance than the STBC strategies in the diversity transmission scenario; and the beamforming scheme can be effectively realized in WCDMA systems employing the subspace tracking and the quantized feedback approach.
Active Fault Isolation in MIMO Systems
DEFF Research Database (Denmark)
Niemann, Hans Henrik; Poulsen, Niels Kjølstad
2014-01-01
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 iso...
An Asymptotic Analysis of the MIMO BC under Linear Filtering
Hunger, Raphael
2008-01-01
We investigate the MIMO broadcast channel in the high SNR regime when linear filtering is applied instead of dirty paper coding. Using a user-wise rate duality where the streams of every single user are not treated as self-interference as in the hitherto existing stream-wise rate dualities for linear filtering, we solve the weighted sum rate maximization problem of the broadcast channel in the dual multiple access channel. Thus, we can exactly quantify the asymptotic rate loss of linear filtering compared to dirty paper coding for any channel realization. Having converted the optimum covariance matrices to the broadcast channel by means of the duality, we observe that the optimal covariance matrices in the broadcast channel feature quite complicated but still closed form expressions although the respective transmit covariance matrices in the dual multiple access channel share a very simple structure. We immediately come to the conclusion that block-diagonalization is the asymptotically optimum transmit strate...
MIMO Precoding for Networked Control Systems with Energy Harvesting Sensors
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.
Power Allocation Optimization: Linear Precoding Adapted to NB-LDPC Coded MIMO Transmission
Directory of Open Access Journals (Sweden)
Tarek Chehade
2015-01-01
Full Text Available In multiple-input multiple-output (MIMO transmission systems, the channel state information (CSI at the transmitter can be used to add linear precoding to the transmitted signals in order to improve the performance and the reliability of the transmission system. This paper investigates how to properly join precoded closed-loop MIMO systems and nonbinary low density parity check (NB-LDPC. The q elements in the Galois field, GF(q, are directly mapped to q transmit symbol vectors. This allows NB-LDPC codes to perfectly fit with a MIMO precoding scheme, unlike binary LDPC codes. The new transmission model is detailed and studied for several linear precoders and various designed LDPC codes. We show that NB-LDPC codes are particularly well suited to be jointly used with precoding schemes based on the maximization of the minimum Euclidean distance (max-dmin criterion. These results are theoretically supported by extrinsic information transfer (EXIT analysis and are confirmed by numerical simulations.
Joint Dirty Paper Coding and Linear Receiver Design for Multiuser MIMO Broadcast Channels
Institute of Scientific and Technical Information of China (English)
CHE Xiao-lin; HE Chen
2008-01-01
A multiuser multiple input multiple output (MIMO) broadcast scheme was proposed through ap-plying dirty paper coding (DPC) at the transmitter and linear equalization at the receiver. Assuming single data stream communication for each user, joint transmitter and linear receiver design were done to enhance the system performance. Furthermore, a multiuser scheduling algorithm was presented to exploit multiuser diversity when the number of the users is larger than that of transmit antennas. The proposed system achieves the sum rate close to the Sato bound and is superior to some of the existing schemes.
5G multimedia massive MIMO communications systems
Ge, Xiaohu; Wang, Haichao; Zi, Ran; Li, Qiang; Ni, Qiang
2016-01-01
In the fifth generation (5G) wireless communication systems, a majority of the traffic demands are contributed by various multimedia applications. To support the future 5G multimedia communication systems, the massive multiple-input multiple-output (MIMO) technique is recognized as a key enabler because of its high spectral efficiency. The massive antennas and radio frequency chains not only improve the implementation cost of 5G wireless communication systems but also result in an intense mut...
A Linear Precoding Scheme for Massive MIMO Systems Based on SSOR Method%一种基于SSOR的大规模MIMO线性预编码方案
Institute of Scientific and Technical Information of China (English)
龙恳; 卿瑞强; 涂斯宇
2016-01-01
大规模多输入多输出系统（Massive MIMO）由于天线数和用户数太大，导致预编码矩阵在求逆是复杂度过高。为了降低复杂度，本文提出了一种基于对称逐步超松弛（SSOR）的线性预编码方案，相比传统的规则化迫零（RZF）预编码方案，本文所提的方案在没有任何性能损失的情况下可以降低一个量级的运算复杂度，为了保证所提SSOR预编码方案的性能，提出一种仅依靠天线配置的简单的量化松弛参数。%Massive multiple-input multiple-output(MIMO) has a large number of attennas and users, which leads to high computational complexity in precoding matrix.To solve this problem,this paper proposed a linear precoding scheme based on symmetric successive overrelaxation(SSOR). Compared to conventional RZF scheme,it can reduce one order of magnitude with negligible performace loss. To guarantee the performance of SSOR-based precoding, we also proposed a simple quantiifed relaxation parameter for SSOR-based scheme, which only depends on the MIMO systemconifguration.
Downlink Assisted Uplink Zero Forcing for TDD Multiuser MIMO Systems
Directory of Open Access Journals (Sweden)
Komulainen Petri
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.
Directory of Open Access Journals (Sweden)
Bahrami Hamid Reza
2007-01-01
Full Text Available The ergodic capacity of MIMO frequency-flat and -selective channels depends greatly on the eigenvalue distribution of spatial correlation matrices. Knowing the eigenstructure of correlation matrices at the transmitter is very important to enhance the capacity of the system. This fact becomes of great importance in MIMO wireless systems where because of the fast changing nature of the underlying channel, full channel knowledge is difficult to obtain at the transmitter. In this paper, we first investigate the effect of eigenvalues distribution of spatial correlation matrices on the capacity of frequency-flat and -selective channels. Next, we introduce a practical scheme known as linear precoding that can enhance the ergodic capacity of the channel by changing the eigenstructure of the channel by applying a linear transformation. We derive the structures of precoders using eigenvalue decomposition and linear algebra techniques in both cases and show their similarities from an algebraic point of view. Simulations show the ability of this technique to change the eigenstructure of the channel, and hence enhance the ergodic capacity considerably.
Active fault detection in MIMO systems
DEFF Research Database (Denmark)
Niemann, Hans Henrik; Poulsen, Niels Kjølstad
2014-01-01
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...... 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...
Upper Capacity Bounds of MIMO Wireless Systems Through Fading Channels
Directory of Open Access Journals (Sweden)
Rachna Mahey
2015-01-01
Full Text Available This paper investigates the upper capacity bounds of MIMO systems with correlation and antenna selection techniques in general fading environments. With Antenna Selection techniques, the increased hardware complexity due to multiple antennas and large number of RF chains can be reduced to a substantial amount, retaining the diversity benefits of MIMO systems. The channel Correlation also affects the capacity of MIMO fading channels. Hence, to evaluate the upper bounds of capacity through fading channels, performance of MIMO systems is exemplified under Nakagami-m and Rayleigh fading channels while considering that the channel characteristics are known at a transmitter. The obtained results give an assessment to the better understanding to the effect of antenna selection and correlation on the capacity of MIMO channels, and how they can be used in different fading environments.
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.
Linear Precoding and Analysis of Performance Criteria in MIMO Interference Channels
Bazzi, Samer
2016-01-01
This thesis treats the downlink transmission in multi-antenna (MIMO) wireless interference channels, and characterizes the spectral efficiency of different linear precoding methods for such channels. These methods include interference alignment, maximum ratio transmission, and eigenmode precoding. The performance characterization of the latter two methods is especially important in massive MIMO scenarios, where these simple techniques exhibit a good performance. The analysis is mainly perform...
Ibnkahla, Mohamed
2012-12-01
Neural network (NN) approaches have been widely applied for modeling and identification of nonlinear multiple-input multiple-output (MIMO) systems. This paper proposes a stochastic analysis of a class of these NN algorithms. The class of MIMO systems considered in this paper is composed of a set of single-input nonlinearities followed by a linear combiner. The NN model consists of a set of single-input memoryless NN blocks followed by a linear combiner. A gradient descent algorithm is used for the learning process. Here we give analytical expressions for the mean squared error (MSE), explore the stationary points of the algorithm, evaluate the misadjustment error due to weight fluctuations, and derive recursions for the mean weight transient behavior during the learning process. The paper shows that in the case of independent inputs, the adaptive linear combiner identifies the linear combining matrix of the MIMO system (to within a scaling diagonal matrix) and that each NN block identifies the corresponding unknown nonlinearity to within a scale factor. The paper also investigates the particular case of linear identification of the nonlinear MIMO system. It is shown in this case that, for independent inputs, the adaptive linear combiner identifies a scaled version of the unknown linear combining matrix. The paper is supported with computer simulations which confirm the theoretical results.
Quantum MIMO n-Systems and Conditions for Stability
Mansourbeigi, Seyed M H
2009-01-01
In this paper we present some conditions for the (strong) stabilizability of an n-D Quantum MIMO system P(X). It contains two parts. The first part is to introduce the n-D Quantum MIMO systems where the coefficients vary in the algebra of Q-meromorphic functions. Then we introduce some conditions for the stabilizability of these systems. The second part is to show that this Quantum system has the n-D system as its quantum limit and the results for the SISO,SIMO,MISO,MIMO are obtained again as special cases.
Spatial Correlation Characterization of a Full Dimension Massive MIMO System
Nadeem, Qurrat-Ul-Ain
2017-02-07
Elevation beamforming and Full Dimension MIMO (FD-MIMO) are currently active areas of research and standardization in 3GPP LTE-Advanced. FD-MIMO utilizes an active antenna array system (AAS), that provides the ability of adaptive electronic beam control over the elevation dimension, resulting in a better system performance as compared to the conventional 2D MIMO systems. FD-MIMO is more advantageous when amalgamated with massive MIMO systems, in that it exploits the additional degrees of freedom offered by a large number of antennas in the elevation. To facilitate the evaluation of these systems, a large effort in 3D channel modeling is needed. This paper aims at providing a summary of the recent 3GPP activity around 3D channel modeling. The 3GPP proposed approach to model antenna radiation pattern is compared with the ITU approach. A closed-form expression is then worked out for the spatial correlation function (SCF) for channels constituted by individual antenna elements in the array by exploiting results on spherical harmonics and Legendre polynomials. The proposed expression can be used to obtain correlation coefficients for any arbitrary 3D propagation environment. Simulation results corroborate and study the derived spatial correlation expression. The results are directly applicable to the analysis of future 5G 3D massive MIMO systems.
FPGA based Smart Wireless MIMO Control System
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.
On Lattice Sequential Decoding for Large MIMO Systems
Ali, Konpal S.
2014-04-01
Due to their ability to provide high data rates, Multiple-Input Multiple-Output (MIMO) wireless communication systems have become increasingly popular. Decoding of these systems with acceptable error performance is computationally very demanding. In the case of large overdetermined MIMO systems, we employ the Sequential Decoder using the Fano Algorithm. 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. We attempt to bound the error by bounding the bias, using the minimum distance of a lattice. Also, a particular trend is observed with increasing SNR: a region of low complexity and high error, followed by a region of high complexity and error falling, and finally a region of low complexity and low error. For lower bias values, the stages of the trend are incurred at lower SNR than for higher bias values. This has the important implication that a low enough bias value, at low to moderate SNR, can result in low error and low complexity even for large MIMO systems. Our work is compared against Lattice Reduction (LR) aided Linear Decoders (LDs). Another impressive observation for low bias values that satisfy the error bound is that the Sequential Decoder\\'s error is seen to fall with increasing system size, while it grows for the LR-aided LDs. For the case of large underdetermined MIMO systems, Sequential Decoding with two preprocessing schemes is proposed – 1) Minimum Mean Square Error Generalized Decision Feedback Equalization (MMSE-GDFE) preprocessing 2) MMSE-GDFE preprocessing, followed by Lattice Reduction and Greedy Ordering. Our work is compared against previous work which employs Sphere Decoding preprocessed using MMSE-GDFE, Lattice Reduction and Greedy Ordering. For the case of large systems, this results in high complexity and difficulty in choosing the sphere radius. Our schemes
A Switched Diversity Scheme for Massive MIMO Systems
Directory of Open Access Journals (Sweden)
Qianya Wang
2014-01-01
Full Text Available With the constraint of antenna space, spatial correlation and mutual coupling must be considered to accurately predict the system performance for massive MIMO systems. Increasing the antenna quantity can degrade the system performance due to mutual coupling. Antenna selection systems have better performance and lower hardware cost than full-MIMO systems. However, the conventional selection combining (SC scheme consumes a great amount of training overhead and has high operational complexity in the presence of mutual coupling. This paper proposes a group switch-and-examine combining (GSEC scheme for massive MIMO systems with the spatial correlation and mutual coupling existing at both the transmitter and receiver. Simulation results demonstrate that the proposed GSEC scheme provides better effective capacity performance and lower operational complexity than the conventional selection combining (SC and full-MIMO scheme.
Channelization Issues with Fairness Considerations for MU-MIMO Precoding Based UTRA-LTE/TDD Systems
DEFF Research Database (Denmark)
Rahman, Muhammad Imadur; Wang, Yuanye; Das, Suvra
2008-01-01
resource allocation point of view, choice of any technique will require different fairness conditions among users. In this paper, we have studied these different fairness conditions when combined with basic or joint access schemes mentioned above, while applied in a MU-MIMO based UTRA-LTE system. We have...... evaluated the resource allocation fairness issue when two well-known linear MU-MIMO precoding is used on a UTRA-LTE system. User grouping issue is dealt with when SDMA component is considered in the system. The results in this work provides an indicative analysis of the usability of different channelization...
Spatial Modulation for MIMO Communication Systems
Directory of Open Access Journals (Sweden)
Reginaldo Nunes
2012-11-01
Full Text Available This work provides a review on the main spatial modulation (SM schemes, suitable to wireless communication systems. Performance, complexity and diversity gain of the three new spatial SM schemes suitable for multiple-input-multiple-output (MIMO communication systems are analyzed: a transmission scheme for spatial modulation (SM scheme; b space shift keying (SSK scheme; c generalized space shift keying (GSSK scheme. These three schemes offer low complexity, higher data rate when compared to single-input-single-output (SISO communication systems, as well as design flexibility, while exploits randomness characteristics of wireless communication channel for data transmission. The paper aims to explore the main features of those three SM schemes and to evaluate the inherent performance-complexity trade-off in order to determine which of those schemes results in a higher energy and spectral efficiencies.
Channel Estimation Techniques in MIMO-OFDM LTE Systems
Directory of Open Access Journals (Sweden)
P. Venkateswarlu
2014-07-01
Full Text Available There is an increasing demand for high data transmission rates with the evolution of the very large scale integration (VLSI technology. The multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM systems are used to fulfill these requirements because of their unique properties such as high spectral efficiency, high data rate and resistance towards multipath propagation. MIMO-OFDM systems are finding their applications in the modern wireless communication systems like IEEE 802.11n, 4G and LTE. They also offer reliable communication with the increased coverage area. The bottleneck to the MIMO-OFDM systems is the estimation of the channel state information (CSI. This can be estimated with the help of any one of the Training Based, Semiblind and Blind Channel estimation algorithms. This paper presents various channel estimation algorithms, optimization techniques and their effective utilization in MIMO-OFDM for modern wireless LTE systems.
On the Performance of Code Acquisition in MIMO CDMA Systems
Kim, Sangchoon; An, Jinyoung
This letter investigates the effects of using multiple transmit antennas on code acquisition for preamble search in the CDMA uplink when MIMO is used for signal transmission and reception. The performance of a ML code acquisition technique in the presence of MIMO channel is analyzed by considering the detection and miss probabilities. The acquisition performance is numerically evaluated on a frequency selective fading channel. It is found that the performance of code acquisition scheme for a SIMO system is better than that for the case of MIMO on the low thresholds in terms of detection performance and MAT.
Multiantenna systems for MIMO communications
DeFlaviis, Franco
2008-01-01
Advanced communication scenarios demand the development of new systemswhere antenna theory, channel propagation and communication models are seen from a common perspective as a way to understand and optimize the system as a whole. In this context, a comprehensive multiantenna formulation for multiple-input multiple-output systems is presented with a special emphasis on the connection of the electromagnetic and communication principles.Starting from the capacity for amultiantenna system, the book reviews radiation, propagation, and communicationmechanisms, paying particular attention to the vec
A 2-order MIMO Full-Duplex Antenna System
DEFF Research Database (Denmark)
Tsakalaki, Elpiniki; Foroozanfard, Ehsan; De Carvalho, Elisabeth
2014-01-01
The paper presents an antenna system with combined full-duplex and 2-order multiple-input-multiple-output (MIMO) functionalities, i.e., a system capable of spatially multiplexing and spatially demultiplexing 2 datastreams in the same frequency and in the same time. By exploiting symmetries....... On the other hand, the 2 MIMO ports (either at the Tx or at the Rx) are sufficiently decoupled thanks to polarization diversity. The proposed antenna system exhibits a remarkable level of fullduplex isolation over a wide bandwidth while maintaining low coupling between its MIMO ports and can serve...... as a concrete implementation of an antenna system equipped with both MIMO as well as full-duplex capabilities....
Low Power Detection Architecture for MIMO Systems
Directory of Open Access Journals (Sweden)
Shirly Edward.A
2013-06-01
Full Text Available This paper presents an architecture for K-best List Sphere Decoder (LSD algorithm for Multiple Input Multiple Output (MIMO Systems using Xilinx System Generator. We made use of an efficient bit-serial architecture, Distributed Arithmetic(DA to reduce the computational complexity involved in the algorithm. The real-valued expanded channel matrix and received vectors are analyzed, designed and implemented using Xilinx Spartan-6 FPGA running at 100MHz. We compare the resource utilization of the conventional implementation of the algorithm with the proposed architecture for different number of layers. The conversion of multipliers into shift and adder units leads to area optimization and reduced power consumption. The total estimated power for our design is found to be 187mW.
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.
Fixed-complexity vector perturbation with Block diagonalization for MU-MIMO systems
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 ...
Maximum-likelihood detection based on branch and bound algorithm for MIMO systems
Institute of Scientific and Technical Information of China (English)
LI Zi; CAI YueMing
2008-01-01
Maximum likelihood detection for MIMO systems can be formulated as an integer quadratic programming problem. In this paper, we introduce depth-first branch and bound algorithm with variable dichotomy into MIMO detection. More nodes may be pruned with this structure. At each stage of the branch and bound algorithm, active set algorithm is adopted to solve the dual subproblem. In order to reduce the com- plexity further, the Cholesky factorization update is presented to solve the linear system at each iteration of active set algorithm efficiently. By relaxing the pruning conditions, we also present the quasi branch and bound algorithm which imple- ments a good tradeoff between performance and complexity. Numerical results show that the complexity of MIMO detection based on branch and bound algorithm is very low, especially in low SNR and large constellations.
Antiwindup analysis and design approaches for MIMO systems
Marcopoli, Vincent R.; Phillips, Stephen M.
1994-01-01
Performance degradation of multiple-input multiple-output (MIMO) control systems having limited actuators is often handled by augmenting the controller with an antiwindup mechanism, which attempts to maintain system performance when limits are encountered. The goals of this paper are: (1) To develop a method to analyze antiwindup systems to determine precisely what stability and performance degradation is incurred under limited conditions. It is shown that by reformulating limited actuator commands as resulting from multiplicative perturbations to the corresponding controller requests, mu-analysis tools can be utilized to obtain quantitative measures of stability and performance degradation. (2) To propose a linear, time invariant (LTI) criterion on which to base the antiwindup design. These analysis and design methods are illustrated through the evaluation of two competing antiwindup schemes augmenting the controller of a Short Take-Off and Vertical Landing (STOVL) aircraft in transition flight.
Institute of Scientific and Technical Information of China (English)
张广辉; 苏成利; 李平
2011-01-01
To solve the shortcomings of traditional PID controllers in dealing with disturbance rejection and robustness, and the over-reliance of model-based control algorithms on mathematical model of the controlled system a model-free adaptive control algorithm is proposed for discrete time MIMO (multiple-input multiple-output) nonlinear systems. In tbis algorithm nonlinear system is Iinearized by linearization of partial format. Then the controlled system parameters are identified on-line by a novel projection algonthm. The parameters are used to recursively compute model-free adaptive control rule. The controller is designed only by using I/O data of the controlled system, and no structural information or extemal testing signals are needed. So the impact of the unmodelled dynamic problem of the modeling process on system performance doesn't exist. Simulation result shows that the proposed algorithm is an effective strategy with excellent tracking ability and strong robustness.%针对常规PID控制器不能很好兼顾抗干扰性与鲁棒性以及基于模型的控制算法过于依赖受控系统数学模型的缺点,提出一种适用于离散时间多输入多输出(MIMO)非线性系统的无模型自适应控制算法.该算法首先通过偏格式线性化方法将非线性系统线性化,再利用一种新型的投影算法在线辨识受控系统参数,根据辨识得到的受控系统参数直接递推计算无模型自适应控制律.控制器的设计仅利用受控系统的I/O数据,不需要受控系统的结构信息和外部实验信号,避免了由建模过程引起的未建模动态问题对控制性能的影响.仿真结果表明该算法具有良好的跟踪性能和较强的鲁棒性.
Linear precoding based on polynomial expansion: reducing complexity in massive MIMO
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.
Linear Transceiver Design in MIMO Relay System%MIMO中继系统中的线性收发机设计
Institute of Scientific and Technical Information of China (English)
关(韦华); 苏中义; 罗汉文
2008-01-01
针对使用单个中继节点的多输入多输出(MIMO)中继系统,以极大化接收端各子流的最小信噪比为目标,提出一种线性收发机设计方案.在此方案中,系统中的各节点沿着对应信道的特征方向进行线性信号处理,使等效的MIMO信道被分解为一组并行的高斯信道.通过优化理论,证明了在中继节点处最优的功率分配,应使接收端各子流具有相同的信噪比.
Optimal beamforming in MIMO systems with HPA nonlinearity
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.
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.
Reconfigurable architecture for MIMO systems based on CORDIC operators
Wang, Hongzhi; Leray, Pierre; Palicot, Jacques
2006-09-01
The MIMO system is an attractive technology for wireless 3G/4G systems. In this article we propose the realization on FPGA of a MIMO 'V-BLAST Square Root' algorithm based on a variable number of CORDIC operators. The CORDIC operator is highly suitable for this implementation as it only relies on simple techniques of addition and vector offsets. This square root algorithm architecture is reconfigurable in order to adapt itself to different numbers of antennas and different data rates. The proposed architecture can achieve a data rate of 600 Mbit/s in a Virtex-II FPGA circuit from Xilinx for the MIMO system with QPSK modulation. To cite this article: H. Wang et al., C. R. Physique 7 (2006).
Energy Efficiency of MIMO-OFDM Communication System
Directory of Open Access Journals (Sweden)
K.Swathi
2014-09-01
Full Text Available With the ever increasing number of subscribers and their seemingly “greedy” demands for high-data-rate services, the next generation networks will have to provide global connectivity to ensure success. So the combination of multiple-input multiple-output (MIMO signal processing with orthogonal frequency division multiplexing (OFDM is regarded as a promising solution for enhancing the data rates of next-generation wireless communication systems operating in frequency-selective fading environments. Therefore hybrid architecture between terrestrial and satellite networks based on MIMO-OFDM with frequency reuse is employed here. However, this frequency reuse introduces severe co-channel interference (CCI at the satellite end. To mitigate CCI, we propose an OFDM based adaptive beamformer implemented on-board the satellite with pilot reallocation at the transmitter side. The system performance is simulated by using the software MATLAB, the experimental result shows that the MIMO-OFDM communication system has better performance when compared.
下行链路多用户MIMO线性收发机设计%Linear transceiver design for downlink transmission in multiuser MIMO systems
Institute of Scientific and Technical Information of China (English)
于斌; 刘拥军; 胡捍英
2012-01-01
针对多用户多天线(MIMO)下行链路系统中的信干噪比(SINR)平衡问题和功率最小化问题，本文基于上下行链路对偶性提出一种新的收发机设计策略。该策略通过首先优化功率和接收滤波器、然后优化预编码器的交互迭代方式，避开传统算法中的复杂特征向量问题，从而极大的降低算法复杂度。仿真结果显示，本文算法具备更好的收敛性，相同性能下所需的计算精度远小于传统算法。
Joint compensation of multiple RF impairments in MIMO STBC systems
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.
Channel Estimation for MIMO MC-CDMA Systems
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.
Allocation Fairness for MIMO Precoded UTRA-LTE TDD System
DEFF Research Database (Denmark)
Wang, Yuanye; Rahman, Muhammad Imadur; Das, Suvra
2008-01-01
In future Time Division Duplex (TDD)-based broadband wireless systems, it will be possible to exploit the channel reciprocity to implement Channel State Information (CSI)-based Multi User Multiple Input Multiple Output (MU-MIMO) techniques, which will ensure highly efficient spectrum usage...... allocation, in MU-MIMO precoding scenarios where the common approach of guaranteeing fairness at MAC layer is not feasible. The results presented in this paper show that the proposed algorithm is able to reduce the system outage event to a large extent, thus increases fairness....
Joint detection and combining schemes in MIMO-HARQ systems
Institute of Scientific and Technical Information of China (English)
XIE Gang; XIONG Fang; ZHAO Yi; LIU Yuan-an
2007-01-01
This article mainly investigates the combining schemes for hybrid automatic retransmission request (HARQ) protocols in multiple-input multiple-output (MIMO) wireless communication systems. A novel scheme, which joins MIMO detection and HARQ combining, called mid-combining, is presented in this article. Based on the position of HARQ combining, we classify the HARQ combining schemes into three types, named pre-combining, mid-combining, and post-combining. The simulation results show that mid- combining can increase the system throughput for all SNRs.
Capacity and Performance of MIMO systems for Wireless Communications
Directory of Open Access Journals (Sweden)
E. Ghayoula
2014-08-01
Full Text Available This paper presents the capacity performance of multiple antennas for wireless communication systems. Multiple antennas structures can be classified into single-input multiple-outputs (SIMO, multiple-inputs single output (MISO, and multiple-inputs multiple-outputs (MIMO systems. Assuming that the channel is unknown at receiver, capacity expressions are provided for each structure. Our results also show that increasing the number of transmitting and receiving antennas for a wireless MIMO channel does indeed improve the channel capacity that can be obtained.
Modified Spatial Channel Model for MIMO Wireless Systems
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Pekka Kyösti
2007-12-01
Full Text Available Ã¯Â»Â¿The third generation partnership Project's (3GPP spatial channel model (SCM is a stochastic channel model for MIMO systems. Due to fixed subpath power levels and angular directions, the SCM model does not show the degree of variation which is encountered in real channels. In this paper, we propose a modified SCM model which has random subpath powers and directions and still produces Laplace shape angular power spectrum. Simulation results on outage MIMO capacity with basic and modified SCM models show that the modified SCM model gives constantly smaller capacity values. Accordingly, it seems that the basic SCM gives too small correlation between MIMO antennas. Moreover, the variance in capacity values is larger using the proposed SCM model. Simulation results were supported by the outage capacity results from a measurement campaign conducted in the city centre of Oulu, Finland.
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...
Institute of Scientific and Technical Information of China (English)
钱栋军; 张静; 顾夏珺
2013-01-01
In MIMO relay system, the scheme of designing the joint linear transmitters and the receiver considering the joint source, relay and destination based on perfect channel state information ( CSI) is derived. Based on this, the paper considering the channel estimate errors modeled as Gaussian random variables and under power constraint at both the source and the relay node, the transmitters and receiver could be realized through a joint iterative algorithm. Compared with the existing methods, the results show that the proposed scheme could effectively improve the BER performance and reduce the minimum mean square error of the system.%在MIMO中继系统中,基于完全信道状态信息的基站、中继节点和终端联合收发机设计方案能够改善系统的误比特率性能,在放大转发(AF)中继的基础上提出了一种基于不完全信道状态信息的联合收发机设计方案.新方案在基站和中继节点的功率都受限条件下,将信道估计误差建模为高斯随机变量,以最小均方误差(MMSE)为准则,采用迭代算法,得到了基站预编码矩阵、中继转发矩阵和终端解码矩阵.该方案与不考虑信道估计误差的方案相比,能够有效地改善系统的均方误差和误比特率性能.
Linear systems optimal and robust control
Sinha, Alok
2007-01-01
Introduction Overview Contents of the Book State Space Description of a Linear System Transfer Function of a Single Input/Single Output (SISO) System State Space Realizations of a SISO System SISO Transfer Function from a State Space Realization Solution of State Space Equations Observability and Controllability of a SISO System Some Important Similarity Transformations Simultaneous Controllability and Observability Multiinput/Multioutput (MIMO) Systems State Space Realizations of a Transfer Function Matrix Controllability and Observability of a MIMO System Matrix-Fraction Description (MFD) MFD of a Transfer Function Matrix for the Minimal Order of a State Space Realization Controller Form Realization from a Right MFD Poles and Zeros of a MIMO Transfer Function Matrix Stability Analysis State Feedback Control and Optimization State Variable Feedback for a Single Input System Computation of State Feedback Gain Matrix for a Multiinput System State Feedback Gain Matrix for a Multi...
Distributed MIMO Systems with Oblivious Antennas
Simeone, Osvaldo; Poor, H Vincent; Shamai, Shlomo
2008-01-01
A scenario in which a single source communicates with a single destination via a distributed MIMO transceiver is considered. The source operates each of the transmit antennas via finite-capacity links, and likewise the destination is connected to the receiving antennas through capacity-constrained channels. Targeting a nomadic communication scenario, in which the distributed MIMO transceiver is designed to serve different standards or services, transmitters and receivers are assumed to be oblivious to the encoding functions shared by source and destination. Adopting a Gaussian symmetric interference network as the channel model (as for regularly placed transmitters and receivers), achievable rates are investigated and compared with an upper bound. It is concluded that in certain asymptotic and non-asymptotic regimes obliviousness of transmitters and receivers does not cause any loss of optimality.
Full-duplex MIMO system based on antenna cancellation technique
DEFF Research Database (Denmark)
Foroozanfard, Ehsan; Franek, Ondrej; Tatomirescu, Alexandru
2014-01-01
The performance of an antenna cancellation technique for a multiple-input– multiple-output (MIMO) full-duplex system that is based on null-steering beamforming and antenna polarization diversity is investigated. A practical implementation of a symmetric antenna topology comprising three dual-pola...
Joint Transceiver Optimization for Multiuser MIMO Amplify-and-Forward Relay Broadcast Systems
Liu, Jun; Zhang, Xiong; Qiu, Zhengding
This letter considers a dual-hop multiuser MIMO amplify-and-forward relay broadcast system with multi-antenna nodes. A unified scheme is addressed to jointly optimize the linear transceiver based on the sum mean-square error (MSE) and the sum rate criterion. The solutions are iteratively obtained by deriving the gradients of the objective functions for a gradient descent algorithm. Simulation results demonstrate the performance improvements in terms of the BER and the sum rate.
Low complexity MIMO sonar imaging using a virtual sparse linear array
Institute of Scientific and Technical Information of China (English)
Xionghou Liu; Chao Sun; Yixin Yang; Jie Zhuo; Yina Han
2016-01-01
A multiple-input multiple-output (MIMO) sonar can synthesize a large-aperture virtual uniform linear array (ULA) from a smal number of physical elements. However, the large aperture is obtained at the cost of a great number of matched filters with much heavy computation load. To reduce the com-putation load, a MIMO sonar imaging method using a virtual sparse linear array (SLA) is proposed, which contains the offline and online processing. In the offline processing, the virtual ULA of the MIMO sonar is thinned to a virtual SLA by the simulated annealing algorithm, and matched filters corre-sponding to inactive virtual elements are removed. In the online processing, outputs of matched filters corresponding to active elements are colected for further multibeam processing and hence, the number of matched filters in the echo proc-essing procedure is effectively reduced. Numerical simula-tions show that the proposed method can reduce the compu-tation load effectively while obtaining a similar imaging per-formance as the traditional method.
Weighted-Sum-Rate-Maximizing Linear Transceiver Filters for the K-User MIMO Interference Channel
Shin, Joonwoo
2012-01-01
This letter is concerned with transmit and receive filter optimization for the K-user MIMO interference channel. Specifically, linear transmit and receive filter sets are designed which maximize the weighted sum rate while allowing each transmitter to utilize only the local channel state information. Our approach is based on extending the existing method of minimizing the weighted mean squared error (MSE) for the MIMO broadcast channel to the K-user interference channel at hand. For the case of the individual transmitter power constraint, however, a straightforward generalization of the existing method does not reveal a viable solution. It is in fact shown that there exists no closed-form solution for the transmit filter but simple one-dimensional parameter search yields the desired solution. Compared to the direct filter optimization using gradient-based search, our solution requires considerably less computational complexity and a smaller amount of feedback resources while achieving essentially the same lev...
A Variational Approach to the Modeling of MIMO Systems
Directory of Open Access Journals (Sweden)
A. Jraifi
2007-05-01
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 Ã¢Â„Â‹. This method, which uses a statistical approach, is based on a variational form of the usual channel equation. The proposed equation is given by ÃŽÂ´2=Ã¢ÂŒÂ©ÃŽÂ´R|Ã¢Â„Â‹|ÃŽÂ´EÃ¢ÂŒÂª+Ã¢ÂŒÂ©ÃŽÂ´R|(ÃŽÂ´Ã¢Â„Â‹|EÃ¢ÂŒÂª with scalar variable ÃŽÂ´=Ã¢Â€Â–ÃŽÂ´RÃ¢Â€Â–. Minimum distance ÃŽÂ´min of received vectors |RÃ¢ÂŒÂª 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.
Variable Structure Control for Unmatched MIMO Nonlinear System with Its Application to MCFC Stacks
Institute of Scientific and Technical Information of China (English)
Xu Chunshan(许春山); Sun Xingjin; Cao Guangyi; Zhu Xinjian
2004-01-01
A new Variable Structure Control (VSC) with Rapid-Smooth Reaching Law (RSRL) and Rapid-Convergent Sliding Mode (FCSM) is proposed, which is based on normal VSC system. When it is used to unmatched MIMO nonlinear system, the authors combine the method of Input/Output Linearizing (I/O L) with VSC: they use the I/O L method to solve the "Unmatched" problem and use the new VSC to get good result of control. After analyzing the robustness of the MIMO nonlinear system, they use this novel controller to the temperature and gas pressure control system of Molten Carbonate Fuel Cell (MCFC) Stacks. Simulation provides quite satisfactory performance with unmatched uncertainties and external disturbances. Its future actual application is practical.
The report documents a series of seminars at Rome Air Development Center with the content equivalent to an intense course in Linear Systems . Material...is slanted toward the practicing engineer and introduces some of the fundamental concepts and techniques for analyzing linear systems . Techniques for
Parasitic antenna arrays for wireless MIMO systems
Kanatas, Athanasios; Papadias, Constantinos
2014-01-01
This book covers a cross-section of two technologies: parasitic antenna arrays driven via analogue circuits; and MIMO technology for multi-antenna arrays. The combination of these two technologies results in novel functionality. Relevant technical angles, ranging from theoretic to electromagnetic considerations; from analogue circuit to digital baseband control for signal generation; and from channel modeling to communication theoretic aspects are detailed by the contributors. Potential applications are considered in conjunction with current and upcoming wireless standards is provided.
Near Capacity Approaching for Large MIMO Systems by Non-Binary LDPC Codes with MMSE Detection
Suthisopapan, Puripong; Meesomboon, Anupap; Imtawil, Virasit
2012-01-01
In this paper, we have investigated the application of non-binary LDPC codes to spatial multiplexing MIMO systems with a large number of low power antennas. We demonstrate that such large MIMO systems incorporating with low-complexity MMSE detector and non-binary LDPC codes can achieve low probability of bit error at near MIMO capacity. The new proposed non-binary LDPC coded system also performs better than other coded large MIMO systems known in the present literature. For instance, non-binary LDPC coded BPSK-MIMO system with 600 transmit/receive antennas performs within 3.4 dB from the capacity while the best known turbo coded system operates about 9.4 dB away from the capacity. Based on the simulation results provided in this paper, the proposed non-binary LDPC coded large MIMO system is capable of supporting ultra high spectral efficiency at low bit error rate.
Characteristic Equation of the Modified Smith predictor to MIMO Systems
Directory of Open Access Journals (Sweden)
Jorge A. Herrera-Cuartas
2013-11-01
Full Text Available The delay in control systems is a feature frequently in real systems due to the transport of objects or information, a series connection of multiple systems or own processing and sensors delay, among others. Recently there have been several studies to identify the external delay MIMO systems, these works are focused on identification and on-line control of MIMO systems and use a multimodel structure based on modified Smith predictor using different search method. It is clear that for the implementation of the algorithm, and to obtain the convergence and stability analysis, it is necessary to have closed-loop equations of modified Smith predictor. However, in these works is not presented the analytical procedure, not be the main object, displaying only the closed loop equations without the procedure for obtaining it. Therefore, to respond, in this paper, we present an analytical way to derive the closed-loop equations of a modified Smith predictor.
Capacity analysis of spectrum sharing spatial multiplexing MIMO systems
Yang, Liang
2014-12-01
This paper considers a spectrum sharing (SS) multiple-input multiple-output (MIMO) system operating in a Rayleigh fading environment. First the capacity of a single-user SS spatial multiplexing system is investigated in two scenarios that assume different receivers. To explicitly show the capacity scaling law of SS MIMO systems, some approximate capacity expressions for the two scenarios are derived. Next, we extend our analysis to a multiple user system with zero-forcing receivers (ZF) under spatially-independent scheduling and analyze the sum-rate. Furthermore, we provide an asymptotic sum-rate analysis to investigate the effects of different parameters on the multiuser diversity gain. Our results show that the secondary system with a smaller number of transmit antennas Nt and a larger number of receive antennas Nr can achieve higher capacity at lower interference temperature Q, but at high Q the capacity follows the scaling law of the conventional MIMO systems. However, for a ZF SS spatial multiplexing system, the secondary system with small Nt and large Nr can achieve the highest capacity throughout the entire region of Q. For a ZF SS spatial multiplexing system with scheduling, the asymptotic sum-rate scales like Ntlog2(Q(KNtNp-1)/Nt), where Np denotes the number of antennas of the primary receiver and K represents the number of secondary transmitters.
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.
EVALUATION OF MIMO SYSTEM CAPACITY OVER RAYLEIGH FADING CHANNEL
Directory of Open Access Journals (Sweden)
Emad. Mohamed
2015-06-01
Full Text Available High transmission data rate, spectral efficiency and reliability are essential for future wireless communications systems. MIMO (multi-input multi-output diversity technique is a band width efficient system achieving high data transmission which eventually establishing a high capacity communication system. Without needing to increase the transmitted power or the channel bandwidth, gain in capacity can be considerably improved by varying the number of antennas on both sides. Correlated and uncorrelated channels MIMO system was considered in this paper for different number of antennas and different SNR over Rayleigh fading channel. At the transmitter both CSI(channel state information technique and Water filling power allocation principle was also considered in this paper
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
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.
A survey of Performance Analysis in MIMO-OFDM Systems
Directory of Open Access Journals (Sweden)
Jitendra Kumar Daksh
2013-06-01
Full Text Available 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.
3D Massive MIMO Systems: Modeling and Performance Analysis
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.
DMT-optimal, Low ML-Complexity STBC-Schemes for Asymmetric MIMO Systems
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...
Design of Joint Spatial and Power Domain Multiplexing Scheme for Massive MIMO Systems
Zheng Jiang; Bin Han; Peng Chen; Fengyi Yang; Qi Bi
2015-01-01
Massive Multiple-Input Multiple-Output (MIMO) is one of the key techniques in 5th generation wireless systems (5G) due to its potential ability to improve spectral efficiency. Most of the existing works on massive MIMO only consider Time Division Duplex (TDD) operation that relies on channel reciprocity between uplink and downlink channels. For Frequency Division Duplex (FDD) systems, with continued efforts, some downlink multiuser MIMO scheme was recently proposed in order to enable “massive...
Sub-channel interference cancellation in SVD-based MIMO system
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
For singular value decomposition (SVD)-based multiple input multiple output (MIMO) systems, implicit channel state information (CSI) incurs interferences amongst sub-channels if the CSI at the transmitter is not explicit.An improved SVD-based MIMO which can fully cancel the inter sub-channel interferences by reconstructing the transmitter- receiver system matrix on interferences analysis is provided.Simulation results indicate that the proposed algorithm outperforms the traditional SVD-based MIMO in a large degree.
System Information Distribution in Massive MIMO Systems
Sörman, Simon
2016-01-01
The 5th generation mobile telecommunication system (5G) is currently being specified and developed, with large expectations on throughput and efficiency. While 4G and more specifically LTE might constitute a basis of the design of the network, there are some parts that should be improved. One thing to improve is the static signalling that occurs very frequently in a 4G network, of which system information such as synchronization signals, detection of network frequencies, operators, configurat...
Hardware Efficient Approximative Matrix Inversion for Linear Pre-Coding in Massive MIMO
Prabhu, Hemanth; Edfors, Ove; Rodrigues, Joachim; Liu, Liang; Rusek, Fredrik
2014-01-01
This paper describes a hardware efficient linear pre-coder for Massive MIMO Base Stations (BSs) comprising a very large number of antennas, say, in the order of 100s, serving multiple users simultaneously. To avoid hardware demanding direct matrix inversions required for the Zero-Forcing (ZF) pre-coder, we use low complexity Neumann series based approximations. Furthermore, we propose a method to speed-up the convergence of the Neumann series by using tri-diagonal pre-condition matrices, whic...
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.
Highly Compact MIMO Antenna System for LTE/ISM Applications
Directory of Open Access Journals (Sweden)
Lingsheng Yang
2015-01-01
Full Text Available Planar monopole antenna is proposed as the antenna element to form a compact dual-element multiple-input-multiple-output (MIMO antenna system for LTE2300 (used in Asia and Africa and ISM band operation. The system can cover a 310 MHz (2.20–2.51 GHz operating bandwidth, with the total size of 15.5 mm × 18 mm × 1.6 mm. Measured isolation higher than 16 dB is obtained without any specially designed decoupling structures, while the edge-to-edge element spacing is only 7.8 mm (0.08λ at 2.20 GHz. Radiation characteristics, correlation coefficient, and the performance of the whole system with a metal sheet and a plastic housing show this system is competitive for practical MIMO applications. The antenna element is further used to build an eight-element MIMO antenna system; also good results are achieved.
Rateless Space Time Block Code for Massive MIMO Systems
Directory of Open Access Journals (Sweden)
Ali H. Alqahtani
2014-01-01
Full Text Available This paper presents a rateless space time block code (RSTBC for massive MIMO systems. The paper illustrates the basis of rateless space time codes deployments in massive MIMO transmissions over wireless erasure channels. In such channels, data may be lost or is not decodable at the receiver due to a variety of factors such as channel fading, interference, or antenna element failure. We show that RSTBC guarantees the reliability of the system in such cases, even when the data loss rate is 25% or more. In such a highly lossy channel, the conventional fixed-rate codes fail to perform well, particularly when channel state information is not available at the transmitter. Simulation results are provided to demonstrate the BER performance and the spectral efficiency of the proposed scheme.
SABA: A Testbed for a Real-Time MIMO System
Directory of Open Access Journals (Sweden)
Brühl Lars
2006-01-01
Full Text Available The growing demand for high data rates for wireless communication systems leads to the development of new technologies to increase the channel capacity thus increasing the data rate. MIMO (multiple-input multiple-output systems are best qualified for these applications. In this paper, we present a MIMO test environment for high data rate transmissions in frequency-selective environments. An overview of the testbed is given, including the analyzed algorithms, the digital signal processing with a new highly parallel processor to perform the algorithms in real time, as well as the analog front-ends. A brief overview of the influence of polarization on the channel capacity is given as well.
Design of RCPC Encoded V-BLAST MIMO System
Directory of Open Access Journals (Sweden)
Lydia Sari
2013-09-01
Full Text Available A Vertical Bell Laboratories Layered Space-Time Multiple-Input Multiple Output (V-BLAST MIMO enhanced with Unequal Error Protection (UEP to achieve highly reliable wireless communication is proposed. The UEP scheme is based on Channel State Information (CSI available at the transmitter whose calculation utilizes Singular Value Decomposition (SVD of the MIMO matrix channel. Using Rate-Compatible Punctured Convolutional (RCPC, a different code rate is given for each sub-stream of source information, according to its level of transmit power. To analyze the system performance, an analytical BER comprising the performance of V-BLAST MIMO BPSK-modulated signals and the performance of RCPC codes in Rayleigh fading environment is presented. Simulation results show that increasing the code rate can attain a bandwidth efficiency of 33.3% in expense Eb/No, but this penalty is not severe as the high code rate is used in sub-channels with high attenuation level. It is also shown that a system with 2 transmit and 4 receive antennas will have an improved performance within only 1 dB range compared to a system with 2 transmit and 2 receive antennas. The performance of the proposed system is mostly affected by the type of puncturing matrices chosen.
Design of RCPC Encoded V-BLAST MIMO System
Directory of Open Access Journals (Sweden)
Lydia Sari
2009-11-01
Full Text Available A Vertical Bell Laboratories Layered Space-Time Multiple-Input Multiple Output (V-BLAST MIMO enhanced with Unequal Error Protection (UEP to achieve highly reliable wireless communication is proposed. The UEP scheme is based on Channel State Information (CSI available at the transmitter whose calculation utilizes Singular Value Decomposition (SVD of the MIMO matrix channel. Using Rate-Compatible Punctured Convolutional (RCPC, a different code rate is given for each sub-stream of source information, according to its level of transmit power. To analyze the system performance, an analytical BER comprising the performance of V-BLAST MIMO BPSK-modulated signals and the performance of RCPC codes in Rayleigh fading environment is presented. Simulation results show that increasing the code rate can attain a bandwidth efficiency of 33.3% in expense Eb/No, but this penalty is not severe as the high code rate is used in sub-channels with high attenuation level. It is also shown that a system with 2 transmit and 4 receive antennas will have an improved performance within only 1 dB range compared to a system with 2 transmit and 2 receive antennas. The performance of the proposed system is mostly affected by the type of puncturing matrices chosen.
Spatial Modulation Concept for Massive Multiuser MIMO Systems
Directory of Open Access Journals (Sweden)
Khaled M. Humadi
2014-01-01
Full Text Available This paper presents the concept of spatial modulation (SM scheme for massive multiuser MIMO (MU-MIMO system. We consider a MU-MIMO system where K users, each equipped with multiple antennas, are jointly serviced by a multiantenna base station transmitter (BSTx using appropriate precoding scheme at the BSTx. The main idea introduced here is the utilization of the user’s subchannel index corresponding to the precoding matrix used at the BSTx, to convey extra useful information. This idea has not been explored, and it provides significant throughput enhancements in a multiuser system with large number of users. We examine the performance of the proposed scheme by numerical simulations. The results show that as the number of users and the receiving antennas for each user increase, the overall system throughput gets better, albeit at the cost of some degradation in the BER performance due to interantenna interference (IAI experienced at the receiver. We then explore zero-padding approach that helps to remove these IAI, in order to alleviate the BER degradations.
Experimental performance bounds of MIMO-FBMC/OQAM systems
Caus, Màrius; Pérez-Neira, Ana Isabel
2010-01-01
This paper addresses the application of filter bank multicarrier (FBMC) systems to multiple-input-multiple-output (MIMO) channels. In particular, it is investigated the FBMC modulation based on OQAM, known as FBMC/OQAM. Existing solutions reveal that FBMC/OQAM remains competitive with the orthogonal frequency division multiplexing (OFDM) technique when the number of streams (S), transmit antennas (NT ) and receive antennas (NR) are related as follows: S = min(NT ,NR). State-of-the-art techniq...
Efficient channel estimation in massive MIMO systems - a distributed approach
Al-Naffouri, Tareq Y.
2016-01-21
We present two efficient algorithms for distributed estimation of channels in massive MIMO systems. The two cases of 1) generic, and 2) sparse channels is considered. The algorithms estimate the impulse response for each channel observed by the antennas at the receiver (base station) in a coordinated manner by sharing minimal information among neighboring antennas. Simulations demonstrate the superior performance of the proposed methods as compared to other methods.
Coding for MIMO-OFDM in future wireless systems
Ahmed, Bannour
2015-01-01
This book introduces the reader to the MIMO-OFDM system, in Rayleigh frequency selective-channels. Orthogonal frequency division multiplexing (OFDM) has been adopted in the wireless local-area network standards IEEE 802.11a due to its high spectral efficiency and ability to deal with frequency selective fading. The combination of OFDM with spectral efficient multiple antenna techniques makes the OFDM a good candidate to overcome the frequency selective problems.
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.
EVALUATION OF BER FOR VARIOUS FADING CHANNEL IN DWT BASED MIMO-OFDM SYSTEM
D.Meenakshi; Prabha, S.; N. R. Raajan
2013-01-01
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 als...
Simplified MMSE Detectors for Turbo Receiver in BICM MIMO Systems
Institute of Scientific and Technical Information of China (English)
Juan Han; Chao Tang; Qiu-Ju Wang; Zi-Yuan Zhu; Shan Tang
2013-01-01
In this article,two methods adopting simplified minimum mean square error (MMSE) filter with soft parallel interference cancellation (SPIC) axe discussed for turbo receivers in bit interleaved coded modulation (BICM) multiple-input multiple-output (MIMO) systems.The proposed methods are utilized in the non-first iterative process of turbo receiver to suppress residual interference and noise.By modeling the components of residual interference after SPIC plus the noise as uncorrelated Gaussian random variables,the matrix inverse for weighting vector of conventional MMSE becomes unnecessary.Thus the complexity can be greatly reduced with only slight performance deterioration.By introducing optimal ordering to SPIC,performance gap between simplified MMSE and conventional MMSE further narrows.Monte Carlo simulation results confirm that the proposed algorithms can achieve almost the same performance as the conventional MMSE SPIC in various MIMO configurations,but with much lower computational complexity.
An Adaptive Channel Estimation Technique in MIMO OFDM Systems
Institute of Scientific and Technical Information of China (English)
Pei-Sheng Pan; Bao-Yu Zheng
2008-01-01
In this paper, an adaptive channel estimation for MIMO OFDM is proposed. A set of pilot tones first are placed in each OFDM block, then the channel frequency response of these pilot tones are adaptively estimated by reeursive least squares (RLS) directly in frequency domain not in time domain. Then after the estimation of the channel frequency response of pilot tones, to obtain the channel frequency response of data tones, a new interpolation method based on DFT different from traditional linear interpolation method according to adjacent pilot tones is proposed. Simulation results show good performance of the technique.
FREQUENCY DOMAIN CRITERIA FOR ROBUST D-STABILITY OF MIMO SYSTEMS BASED ON LMI METHOD
Institute of Scientific and Technical Information of China (English)
LI Hai-bin; WANG Zhi-zhen; WANG Long; LI Zhao-ping; LI Er-xiao
2006-01-01
The problem of checking robust D-stability of multi-in and multi-out (MIMO) systems was studied. Three system models were introduced, i.e. multilinear polynomial matrix, polytopic polynomial matrix and feedback system model. Furthermore, the convex property of each model with respect to the parametric uncertainties was estabilished respectively. Based on this, sufficient conditions for D-stability were expressed in terms of linear matrix inequalities (LMIs) involving only the convex vertices. Therefore, the robust D-stability was tested by solving an LMI optimal problem.
Downlink Performance of a Multi-Carrier MIMO System in a Bursty Traffic Cellular Network
DEFF Research Database (Denmark)
Nguyen, Hung Tuan; Kovacs, Istvan; Wang, Yuanye
2011-01-01
In this paper we analyse the downlink performance of a rank adaptive multiple input multiple output (MIMO) system in a busty traffic cellular network. A LTE-Advanced system with multiple component carriers was selected as a study case. To highlight the advantage of using MIMO techniques, we used...
Massive MIMO Wireless Networks: An Overview
Directory of Open Access Journals (Sweden)
Noha Hassan
2017-09-01
Full Text Available Massive multiple-input-multiple-output (MIMO systems use few hundred antennas to simultaneously serve large number of wireless broadband terminals. It has been incorporated into standards like long term evolution (LTE and IEEE802.11 (Wi-Fi. Basically, the more the antennas, the better shall be the performance. Massive MIMO systems envision accurate beamforming and decoding with simpler and possibly linear algorithms. However, efficient signal processing techniques have to be used at both ends to overcome the signaling overhead complexity. There are few fundamental issues about massive MIMO networks that need to be better understood before their successful deployment. In this paper, we present a detailed review of massive MIMO homogeneous, and heterogeneous systems, highlighting key system components, pros, cons, and research directions. In addition, we emphasize the advantage of employing millimeter wave (mmWave frequency in the beamforming, and precoding operations in single, and multi-tier massive MIMO systems.
A TRIBAND SWASTIKA SHAPED PATCH ANTENNA WITH REDUCED MUTUAL COUPLING FOR WIRELESS MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
K Jagadeesh Babu; K Sri Ramakrishna; L Pratap Reddy
2011-01-01
A novel compact Swastika shaped patch antenna is designed in the present work,which can be used for Multiple Input Multiple Output (MIMO) systems.The proposed two element MIMO system resonates at a triband of 3.3 GHz,5.8 GHz,and 7.1 GHz with an improved impedance bandwidth of 37％ and a reduced mutual coupling of -33 dB.These results are better compared to a normal E shaped patch antenna designed with same size and thickness,achieved without using any additional decoupling methods.A 2 × 2 MIMO system employing the Swastika shaped patch antennas is analyzed using computational electromagnetic ray tracing software for an indoor environment.The results show an improvement in the capacity compared to a 2 × 2 MIMO system developed with dipole antennas.The proposed antenna is a good choice for MIMO systems operating for several Ultra WideBand (UWB) applications.
Complexity Reduction in ML Decoding For MIMO Systems
Directory of Open Access Journals (Sweden)
Ramya Jothikumar
2013-05-01
Full Text Available In this paper, we propose a combined Breadth first tree search ML (Maximum Likelihood-ZF (Zero Forcing method of detection for Spatial Multiplexed MIMO (Multiple Input Multiple Output systems with reduced complexity. The detection of real and imaginary parts of QAM (Quadrature Amplitude Modulation modulated symbol is carried out in successive level of tree which makes parallel processing possible. Reduction in complexity compared to conventional ML for a 2x2 system is 80% and for a 4x4 system is 83%
A Fast Adaptive Receive Antenna Selection Method in MIMO System
Directory of Open Access Journals (Sweden)
Chaowei Wang
2013-01-01
Full Text Available Antenna selection has been regarded as an effective method to acquire the diversity benefits of multiple antennas while potentially reduce hardware costs. This paper focuses on receive antenna selection. According to the proportion between the numbers of total receive antennas and selected antennas and the influence of each antenna on system capacity, we propose a fast adaptive antenna selection algorithm for wireless multiple-input multiple-output (MIMO systems. Mathematical analysis and numerical results show that our algorithm significantly reduces the computational complexity and memory requirement and achieves considerable system capacity gain compared with the optimal selection technique in the same time.
Evaluation of massive MIMO systems using time-reversal beamforming technique
DEFF Research Database (Denmark)
Mbeutcha, Marie; Fan, Wei; Hejselbæk, Johannes
2016-01-01
In this paper, we investigate the performance of a massive MIMO system using the time-reversal beamforming technique. The massive MIMO channels are simulated with ray-tracing at 3.5 GHz with a 200 MHz-bandwidth. We use a 64-element uniform cylindrical array as base station (BS) and we equip two...
A Modified E Shaped Patch Antenna For Mimo Systems
Directory of Open Access Journals (Sweden)
K. Jagadeesh Babu
2010-10-01
Full Text Available A compact E shaped patch antenna is proposed in the present work, which can be used for Multiple Input Multiple output (MIMO systems. The modified E shaped patch antenna proposed in this paper offers improved directivity, bandwidth, and return loss characteristics compared to normal E shaped antenna. The antenna system resonates at 5.36GHz and 5.89GHz frequencies for VSWR≤2 which can be used for WiMAX (Wireless interoperability for microwave access applications. The simulation results of return loss, VSWR, gain and radiation pattern are presented.
AN EFFICIENT APPROXIMATE MAXIMUM LIKELIHOOD SIGNAL DETECTION FOR MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
Cao Xuehong
2007-01-01
This paper proposes an efficient approximate Maximum Likelihood (ML) detection method for Multiple-Input Multiple-Output (MIMO) systems, which searches local area instead of exhaustive search and selects valid search points in each transmit antenna signal constellation instead of all hyperplane. Both of the selection and search complexity can be reduced significantly. The method performs the tradeoff between computational complexity and system performance by adjusting the neighborhood size to select the valid search points. Simulation results show that the performance is comparable to that of the ML detection while the complexity is only as the small fraction of ML.
High Throughput Constant Envelope Pre-coder for Massive MIMO Systems
Prabhu, Hemanth; Rusek, Fredrik; Rodrigues, Joachim; Edfors, Ove
2015-01-01
This study describes a high throughput constant envelope (CE) pre-coder for Massive MIMO systems. A large number of antennas (M), in the order of 100s, serve a relatively small number of users (K) simultaneously. The stringent amplitude constraint (only phase changes) in the CE scheme is motivated by the use of highly power-efficient non-linear RF power amplifiers. We propose a scheme that computes the CE signals to be transmitted based on box-constrained regression (coordinatedescent),with a...
Directory of Open Access Journals (Sweden)
Jan Bajcsy
2005-07-01
Full Text Available This paper considers the problem of uplink transmission over multiple-input multiple-output (MIMO channels affected by slow frequency-nonselective uncorrelated and correlated Rayleigh fading. We consider the case when channel state information, corrupted by estimation errors, is available at the receiver only. In this setting, we generalize the derivation of our previously proposed linear-complexity MIMO signal detector and derive closed-form expressions for the distribution of its soft outputs and the approximate symbol error probability. Based on this soft decision detector, we consider a turbo-coded MIMO uplink architecture with iterative processing, which enables performance within 1.6 to 2.8 dB of the ergodic capacity limit and outperforms the T-BLAST (turbo-Bell Laboratories layered space-time system by about 10 dB at bit error rates of 10Ã¢ÂˆÂ’5. The presented results illustrate that this linear-complexity MIMO signal detector is highly robust to channel estimation errors.
Application of Feedback Linearization Method in Airplane Automatic Landing Control System
Institute of Scientific and Technical Information of China (English)
Wang Xiaoyan; Feng Jiang; Feng Xiujuan; Wu Junqin
2004-01-01
Summarizes the I/O feedback linearization about MIMO system, and applies it to nonlinear control equation of airplane. And also designs the tracing control laws for airplane longitudinal automatic landing control system.
Bourlès, Henri
2013-01-01
Linear systems have all the necessary elements (modeling, identification, analysis and control), from an educational point of view, to help us understand the discipline of automation and apply it efficiently. This book is progressive and organized in such a way that different levels of readership are possible. It is addressed both to beginners and those with a good understanding of automation wishing to enhance their knowledge on the subject. The theory is rigorously developed and illustrated by numerous examples which can be reproduced with the help of appropriate computation software. 60 exe
Power Efficient Low Complexity Precoding for Massive MIMO Systems
Sifaou, Houssem; Kammoun, Abla; Sanguinetti, Luca; Debbah, Merouane; Alouini, Mohamed-Slim
2014-01-01
International audience; 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 prec...
A MULTI-CRC SELECTIVE HARQ SCHEME FOR MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
A multi-Cyclic Redundancy Check (CRC) selective Hybrid Automatic-Repeat-reQuest (HARQ) scheme for improving the throughput efficiency of Multiple Input Multiple Output (MIMO) systems is proposed in this paper. According to different feedback information from the receiver, the proposed HARQ scheme employs two strategies, referred to as retransmission frame selection and space diversity. These two strategies decrease the successive frame errors upon retransmission. Theoretic analysis and computer simulation results show that this HARQ scheme achieves higher throughput than the existing HARQ schemes even in poor conditions of low Signal-to-Noise Ratio (SNR).
Distributive estimation of frequency selective channels for massive MIMO systems
Zaib, Alam
2015-12-28
We consider frequency selective channel estimation in the uplink of massive MIMO-OFDM systems, where our major concern is complexity. A low complexity distributed LMMSE algorithm is proposed that attains near optimal channel impulse response (CIR) estimates from noisy observations at receive antenna array. In proposed method, every antenna estimates the CIRs of its neighborhood followed by recursive sharing of estimates with immediate neighbors. At each step, every antenna calculates the weighted average of shared estimates which converges to near optimal LMMSE solution. The simulation results validate the near optimal performance of proposed algorithm in terms of mean square error (MSE). © 2015 EURASIP.
SPATIAL COMPATIBLE USER GROUPING ALGORITHM FOR MULTIUSER MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
Li Lei; Niu Zhisheng
2007-01-01
A spatial compatible user grouping algorithm is proposed to reduce CoChannel Interference (CCI) in Space Division Multiple Access (SDMA) multiuser Multiple Input Multiple Output (MIMO)systems. We evaluate the interferences among users by use of distances between row spaces spanned by users' channel matrixes, then control frequency sharing according to the compatible user grouping algorithm. Results show that the row space distance algorithm outperforms others because it can fully utilize the information from users' channel matrixes, especially the matrix structure information. The results also prove that the algorithm based on channel matrix structure analysis is a better candidate for spatial compatibility approximation.
Near-Optimal Detection in MIMO Systems using Gibbs Sampling
DEFF Research Database (Denmark)
Hansen, Morten; Hassibi, Babak; Dimakis, Georgios Alexandros
2009-01-01
In this paper we study a Markov Chain Monte Carlo (MCMC) Gibbs sampler for solving the integer least-squares problem. In digital communication the problem is equivalent to preforming Maximum Likelihood (ML) detection in Multiple-Input Multiple-Output (MIMO) systems. While the use of MCMC methods...... for such problems has already been proposed, our method is novel in that we optimize the "temperature" parameter so that in steady state, i.e., after the Markov chain has mixed, there is only polynomially (rather than exponentially) small probability of encountering the optimal solution. More precisely, we obtain...
Bayesian integer frequency offset estimator for MIMO-OFDM systems
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Carrier frequency offset (CFO) in MIMO-OFDM systems can be decoupled into two parts: fraction frequency offset (FFO) and integer frequency offset (IFO). The problem of IFO estimation is addressed and a new IFO estimator based on the Bayesian philosophy is proposed. Also, it is shown that the Bayesian IFO estimator is optimal among all the IFO estimators. Furthermore, the Bayesian estimator can take advantage of oversampling so that better performance can be obtained. Finally, numerical results show the optimality of the Bayesian estimator and validate the theoretical analysis.
Optimal training sequences for MIMO systems under correlated fading
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
The optimal design of training sequences for channel estimation in multiple-input multiple-output (MIMO) systems under spatially correlated fading is considered.The channel is assumed to be a block-fading model with spatial correlation known at both the transmitter and the receiver.To minimize the channel estimation error,optimal training sequences are designed to exploit full information of the spatial correlation under the criterion of minimum mean square error (MMSE).It is investigated that the spatial correlation is helpful to decrease the estimation error and the proposed training sequences have good performance via simulations.
On the power amplifier nonlinearity in MIMO transmit beamforming systems
Qi, Jian
2012-03-01
In this paper, single-carrier multiple-input multiple-output (MIMO) transmit beamforming (TB) systems in the presence of high-power amplifier (HPA) nonlinearity are investigated. Specifically, due to the suboptimality of the conventional maximal ratio transmission/maximal ratio combining (MRT/MRC) under HPA nonlinearity, we propose the optimal TB scheme with the optimal beamforming weight vector and combining vector, for MIMO systems with nonlinear HPAs. Moreover, an alternative suboptimal but much simpler TB scheme, namely, quantized equal gain transmission (QEGT), is proposed. The latter profits from the property that the elements of the beamforming weight vector have the same constant modulus. The performance of the proposed optimal TB scheme and QEGT/MRC technique in the presence of the HPA nonlinearity is evaluated in terms of the average symbol error probability and mutual information with the Gaussian input, considering the transmission over uncorrelated quasi-static frequency-flat Rayleigh fading channels. Numerical results are provided and show the effects on the performance of several system parameters, namely, the HPA parameters, numbers of antennas, quadrature amplitude modulation modulation order, number of pilot symbols, and cardinality of the beamforming weight vector codebook for QEGT. © 2012 IEEE.
Power optimization for maximum channel capacity in MIMO relay system
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Introducing multiple-input multiple-output (MIMO) relay channel could offer significant capacity gain.And it is of great importance to develop effective power allocation strategies to achieve power efficiency and improve channel capacity in amplify-and-forward relay system.This article investigates a two-hop MIMO relay system with multiple antennas in relay node (RN) and receiver (RX).Maximizing capacity with antenna selection (MCAS) and maximizing capacity with eigen-decomposition (MCED) schemes are proposed to efficiently allocate power among antennas in RN under first and second hop limited scenarios.The analysis and simulation results show that both MCED and MCAS can improve the channel capacity compared with uniform power allocation (UPA) scheme in most of the studied areas.The MCAS bears comparison with MCED with an acceptable capacity loss, but lowers the complexity by saving channel state information (CSI) feedback to the transmitter (TX).Moreover, when the RN is close to RX, the performance of UPA is also close to the upper bound as the performance of first hop is limited.
Efficient optimal joint channel estimation and data detection for massive MIMO systems
Alshamary, Haider Ali Jasim
2016-08-15
In this paper, we propose an efficient optimal joint channel estimation and data detection algorithm for massive MIMO wireless systems. Our algorithm is optimal in terms of the generalized likelihood ratio test (GLRT). For massive MIMO systems, we show that the expected complexity of our algorithm grows polynomially in the channel coherence time. Simulation results demonstrate significant performance gains of our algorithm compared with suboptimal non-coherent detection algorithms. To the best of our knowledge, this is the first algorithm which efficiently achieves GLRT-optimal non-coherent detections for massive MIMO systems with general constellations.
Performance Analysis of 3D Massive MIMO Cellular Systems with Collaborative Base Station
Directory of Open Access Journals (Sweden)
Xingwang Li
2014-01-01
Full Text Available Massive MIMO have drawn considerable attention as they enable significant capacity and coverage improvement in wireless cellular network. However, pilot contamination is a great challenge in massive MIMO systems. Under this circumstance, cooperation and three-dimensional (3D MIMO are emerging technologies to eliminate the pilot contamination and to enhance the performance relative to the traditional interference-limited implementations. Motivated by this, we investigate the achievable sum rate performance of MIMO systems in the uplink employing cooperative base station (BS and 3D MIMO systems. In our model, we consider the effects of both large-scale and small-scale fading, as well as the spatial correlation and indoor-to-outdoor high-rise propagation environment. In particular, we investigate the cooperative communication model based on 3D MIMO and propose a closed-form lower bound on the sum rate. Utilizing this bound, we pursue a “large-system” analysis and provide the asymptotic expression when the number of antennas at the BS grows large, and when the numbers of antennas at transceiver grow large with a fixed ratio. We demonstrate that the lower bound is very tight and becomes exact in the massive MIMO system limits. Finally, under the sum rate maximization condition, we derive the optimal number of UTs to be served.
Massive MIMO-OFDM indoor visible light communication system downlink architecture design
Lang, Tian; Li, Zening; Chen, Gang
2014-10-01
Multiple-input multiple-output (MIMO) technique is now used in most new broadband communication system, and orthogonal frequency division multiplexing (OFDM) is also utilized within current 4th generation (4G) of mobile telecommunication technology. With MIMO and OFDM combined, visible light communication (VLC) system's diversity gain is increase, yet system capacity for dispersive channels is also enhanced. Moreover, with the emerging massive MIMO-OFDM VLC system, there are significant advantages than smaller systems' such as channel hardening, further increasing of energy efficiency (EE) and spectral efficiency (SE) based on law of large number. This paper addresses one of the major technological challenges, system architecture design, which was solved by semispherical beehive structure (SBS) receiver and so that diversity gain can be identified and applied in Massive MIMO VLC system. Simulation results shows that the proposed design clearly presents a spatial diversity over conventional VLC systems.
Feedback Reduction in Uplink MIMO OFDM Systems by Chunk Optimization
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Arogyaswami Paulraj
2008-01-01
Full Text Available The performance of multiuser MIMO systems can be significantly increased by channel-aware scheduling and signal processing at the transmitters based on channel state information. In the multipleantenna uplink multicarrier scenario, the base station decides centrally on the optimal signal processing and spectral power allocation as well as scheduling. An interesting challenge is the reduction of the overhead in order to inform the mobiles about their transmit strategies. In this work, we propose to reduce the feedback by chunk processing and quantization. We maximize the weighted sum rate of a MIMO OFDM MAC under individual power constraints and chunk size constraints. An efficient iterative algorithm is developed and convergence is proved. The feedback overhead as a function of the chunk size is considered in the rate computation and the optimal chunk size is determined by numerical simulations for various channel models. Finally, the issues of finite modulation and coding schemes as well as quantization of the precoding matrices are addressed.
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......In this paper the influence of mutual coupling on the capacity of a multiple-input multiple-output (MIMO) antenna system is demonstrated. No direct relation between the envelope correlation and the actual location and orientation of the antennas is found. Even though being essential for high MIMO...
Analysis and Evaluation of Performance Gains and Tradeoffs for Massive MIMO Systems
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Saba Qasim Jabbar
2016-09-01
Full Text Available Massive MIMO technique offers significant performance gains for the future of wireless communications via improving the spectral efficiency, energy efficiency and the channel quality with simple linear processing such as maximum-ratio transmission (MRT or zero-forcing (ZF by providing each user a large degree of freedom. In this paper, the system performance gains are studied in a multi-cell downlink massive MIMO system under the main considerations such as perfect channel estimation, imperfect channel estimation and the effect of interference among cells due to pilot sequences contamination. Then, mathematical expressions are derived for these gains i.e., spatial multiplexing gain, array gain and spatial diversity gain. After that, essential tradeoffs among these gains are considered under the effect of non-orthogonal interference, these tradeoffs are: spatial diversity gain vs. spatial multiplexing gain and array gain vs. spatial multiplexing gain. Simulation results show that the unbounded number of base station antennas boosts the array gain through concentrating the energy to spatial directions where users are sited, hence diminishing loss in array gain due to pilot contamination. The simulation results reveal also that massive MIMO strengthens the spatial multiplexing gain through increasing the number of served users via the same system resources in spite the effect of inter-cell interference. Finally, the spatial diversity gain is measured in term of outage probability and the simulation results show that raising the number of antennas will improve the outage probability. Meanwhile increasing the number of served users will lead to degrade the outage probability per user due to non-orthogonal interference from other cells.
MIMO Communication for Cellular Networks
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,...
Optimization of MIMO Systems Capacity Using Large Random Matrix Methods
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Philippe Loubaton
2012-11-01
Full Text Available This paper provides a comprehensive introduction of large random matrix methods for input covariance matrix optimization of mutual information of MIMO systems. It is first recalled informally how large system approximations of mutual information can be derived. Then, the optimization of the approximations is discussed, and important methodological points that are not necessarily covered by the existing literature are addressed, including the strict concavity of the approximation, the structure of the argument of its maximum, the accuracy of the large system approach with regard to the number of antennas, or the justification of iterative water-filling optimization algorithms. While the existing papers have developed methods adapted to a specific model, this contribution tries to provide a unified view of the large system approximation approach.
Performance analysis of spatial multiplexing MIMO system with time reversal technology
Shrestha, Sanjeeb; Dou, Zheng; Khan, Zayed
2013-03-01
This paper deals with the performance analysis of Spatial Multiplexing(SM) multiple input multiple output (MIMO) system with time reversal (TR) technology. Focus is given on the spatial multiplexing gain of MIMO than the diversity gain aspect with the notion that the idea of diversity is inseparably associated with the uncertainty of the channel. If transmitter knows Channel State Information (CSI) before transmission, potential benefits can be harvested. TR is used here, to provide Channel State Information (CSI) at the transmitter before transmission. With the features of temporal and spatial focusing, TR not only can provide immunity against fading for spatially multiplexed data stream but also help boost its Multi Stream Interference (MSI) limited performance by mitigating it. The performance analysis of SM-MIMOTR is carried out with the aim of average minimum error probability for quantity of interest data rate. The interest date rate is 19.07 Mbps, where as the average minimum error probably is set to be that of Single Input Multi Output (SIMO) maximum ratio combining system (MRC). BER of Single Input Single Output (SISO) system is also simulated for making comparison tangible. Simulation study shows that Bit Error Rate (BER) performance of the system with the data rate of interest nearly coincides with that of SIMO system at the range of 10-15db and is better than SISO in all simulated Eb/No points. Additionally, from the standpoint of tread off curve, between diversity gain and spatial multiplexing gain, the non linearity nature still holds.
分布式MIMO-OFDM定时同步算法的研究及比较%Comparative Timing Synchronization Method for Distributed MIMO-OFDM Systems
Institute of Scientific and Technical Information of China (English)
张驰; 韩太林; 陈小云
2014-01-01
Multiple input multiple output-orthogonal frequency division multiplexing MIMO-OFDM technology is the core of the next generation(4G) of communication technology. MIMO-OFDM has the advantages of high spectrum efficiency, strong anti-interference capability and large Channel capacity. Distributed MIMO-OFDM system can produce time delay and frequency offset. It is also very sensitive to the timing and frequency offset. So, the study of distributed MIMO-OFDM synchronization algorithm is more practical significance. The article made a comprehensive analysis and summary from the sequence structure and the performance of these three current kinds of distributed MIMO-OFDM timing synchronization algorithm, and through the MATLAB simulation comparison. It acquires to use CAZAC sequence as subcarrier data reverse conjugate timing algorithm has outstanding performance.%多输入多输出-正交频分复用(MIMO-OFDM)技术是下一代4G 通信的核心技术，具有频谱利用率高，抗干扰能力强，信道容量大等优点。分布式MIMO-OFDM系统会产生多时延、多频偏，同时对定时和频偏非常敏感，所以对分布式MIMO-OFDM同步算法的研究更加具有实际意义。文章对目前三种分布式MIMO-OFDM定时同步算法从序列结构，性能做了全面的比较分析与总结，并通过MATLAB仿真进行比较，得出运用CAZAC序列作为子载波数据的反向共轭定时算法性能突出。
Channel estimation in space and frequency domain for MIMO-OFDM systems
Institute of Scientific and Technical Information of China (English)
PAN Pei-sheng; ZHENG Bao-yu
2009-01-01
Multiple-input multiple-output (MIMO) systems can be combined with orthogonal frequency division multiplexing (OFDM) systems to improve the capacity and quality of wireless communications. In this article, a channel estimation technique in both space and frequency domain for MIMO-OFDM systems is proposed. It is shown that the proposed scheme with space-frequency pilot tones achieve optimal minimum mean square error (MMSE) channel estimation. Simulation results indicate that the proposed method achieves good performance.
Directory of Open Access Journals (Sweden)
Wajdi Belhaj
2017-01-01
Full Text Available In this paper, a MIMO PI design procedure is proposed for linear time invariant (LTI systems with multiple time delays. The controller tuning is established in two stages and guarantees performances for set-point changes, disturbance variations, and parametric uncertainties. In the first stage, an iterative linear matrix inequality (ILMI approach is extended to design PI controllers for systems with multiple time delays without performance guarantee, a priori. The second stage is devoted to improve the closed-loop performances by minimizing sensitivity functions. Simulations results carried out on the unstable distillation column, the stable industrial scale polymerization (ISP reactor, and the non-minimum phase 4-tank benchmark prove the efficiency of the proposed approach. A comparative analysis with the conventional internal model control (IMC approach, a multiloop IMC-PI approach, and a previous ILMI PID approach proves the superiority of the proposed approach compared to the related ones.
Multiple Antennas Arm Effective MIMO Systems
DEFF Research Database (Denmark)
Thaysen, Jesper; Jakobsen, Kaj Bjarne
2007-01-01
Understanding the interactions among different combinations of receive and transmit antenna elements can help increase the capacity of cellular wireless systems.......Understanding the interactions among different combinations of receive and transmit antenna elements can help increase the capacity of cellular wireless systems....
3D Massive MIMO Systems: Channel Modeling and Performance Analysis
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
Performance Improvement of BER in MIMO Systems with SVD-Based Precoding Approach
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Akash Sethi
2013-10-01
Full Text Available Interference is the factor which limits the performance in cellular network. Empowered by precoding and decoding, a spatially multiplexed Multiple-Input Multiple-Output (MIMO system becomes a convenient framework to offer high data rate, diversity and interference management. In this paper, we discuss precoding scheme to mitigate the effect of channel fading in MIMO system where there is no limit in number of antennas at transmitter and receiver. With the knowledge of channel state information (CSI the transmitted signal is defined such that the channel fading effect is greatly mitigated. This will improve the BER performance of the MIMO system. For our proposed scheme, we use the Singular Value Decomposition (SVD based approach to design the transmitted signal such that it mitigate the effect of channel fading. After simulation, we observe that the BER performance of MIMO system is better than when equalization technique used alone.
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Jianfeng Zheng
2012-01-01
Full Text Available This paper is aimed at studying the impacts of mutual coupling, matching networks, and polarization of antennas on performances of Multiple-Input Multiple-Output (MIMO systems employing Spatial Multiplexing (SM. In particular, the uncoded average Bit Error Rate (BER of MIMO systems is investigated. An accurate signal analysis framework based on circuit network parameters is presented to describe the transmit/receive characteristics of the matched/unmatched antenna array. The studied arrays consist of matched/unmatched compact copolarization and polarization diversity antenna array. Monte-Carlo numerical simulations are used to study the BER performances of the SM MIMO systems using maximum-likelihood and/or zero-forcing detection schemes. The simulation results demonstrate that the use of matching networks can improve the BER performance of SM MIMO systems significantly, and the BER performance deterioration due to antenna orientation randomness can be compensated by use of polarization diversity antenna arrays.
Performance Analysis of Precoding Based on Massive MIMO System
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Li Yi
2015-01-01
Full Text Available In order to improve the system performance, the authors consider a single-cell multiuser Massive MIMO downlink time-division duplex (TDD system for the imperfect channel state information (CSI. For the zero-forcing (ZF and the matched filtering (MF precoding scheme, the authors propose a normalization algorithm: the vector normalization. Assume that the channel estimation is used to acquire CSI by using the uplink pilot sequence, and utilize the proposed algorithm to normalize the precoding matrix in the downlink; we derive the achievable sum rate of ZF and MF. Through the analysis and comparison of two precoding schemes’ performance, the authors conclude that ZF is better than MF with vector normalization algorithm in the high SNR region; and MF is better than ZF in the low SNR region. Simulation results confirm the above conclusion.
Study and Analysis Capacity of MIMO Systems for AWGN Channel Model Scenarios
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Hussain Bohra
2014-10-01
Full Text Available Future wireless communication systems can utilize the spatial properties of the wireless channel to enhance the spectral efficiency and therefore increases its channel capacity. This can be designed by deploying multiple antennas at both the transmitter side and receiver side. The basic measure of performance is the capacity of a channel; the maximum rate of communication for which arbitrarily small error probability can be achieved. The AWGN (additive white Gaussian noise channel introduces the notion of capacity through a heuristic argument. The AWGN channel is then used as a basic building block to check the capacity of wireless fading channels in contrast to the AWGN channel. There is no single definition of capacity for fading channels that is applicable in all situations. Several notions of capacity are developed, and together they form a systematic study of performance limits of fading channels. The various capacity measures allow us to observe clearly the various types of resources available in fading channels: degrees of freedom, power and diversity. The MIMO systems capacity can be enhanced linearly with large the number of antennas. This paper elaborates the study of MIMO system capacity using the AWGN Channel Model, Channel Capacity, Channel Fast Fading, Spatial Autocorrelation and Power delay profile for various channel environments.
The analysis of MAI in large scale MIMO-CDMA system
Berceanu, Madalina-Georgiana; Voicu, Carmen; Halunga, Simona
2016-12-01
Recently, technological development imposed a rapid growth in the use of data carried by cellular services, which also implies the necessity of higher data rates and lower latency. To meet the users' demands, it was brought into discussion a series of new data processing techniques. In this paper, we approached the MIMO technology that uses multiple antennas at the receiver and transmitter ends. To study the performances obtained by this technology, we proposed a MIMO-CDMA system, where image transmission has been used instead of random data transmission to take benefit of a larger range of quality indicators. In the simulations we increased the number of antennas, we observed how the performances of the system are modified and, based on that, we were able to make a comparison between a conventional MIMO and a Large Scale MIMO system, in terms of BER and MSSIM index, which is a metric that compares the quality of the image before transmission with the received one.
Spectral Subtraction Approach for Interference Reduction of MIMO Channel Wireless Systems
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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.
Covert Communication in MIMO-OFDM System Using Pseudo Random Location of Fake Subcarriers
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Rizky Pratama Hudhajanto
2016-08-01
Full Text Available Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM is the most used wireless transmission scheme in the world. However, its security is the interesting problem to discuss if we want to use this scheme to transmit a sensitive data, such as in the military and commercial communication systems. In this paper, we propose a new method to increase the security of MIMO-OFDM system using the change of location of fake subcarrier. The fake subcarriers’ location is generated per packet of data using Pseudo Random sequence generator. The simulation results show that the proposed scheme does not decrease the performance of conventional MIMO-OFDM. The attacker or eavesdropper gets worse Bit Error Rate (BER than the legal receiver compared to the conventional MIMO-OFDM system.
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Qifeng Zou
2016-01-01
Full Text Available The emerging large-scale/massive multi-input multioutput (MIMO system combined with orthogonal frequency division multiplexing (OFDM is considered a key technology for its advantage of improving the spectral efficiency. In this paper, we introduce an iterative detection algorithm for uplink large-scale multiuser MIMO-OFDM communication systems. We design a Main-Branch structure iterative turbo detector using the Approximate Message Passing algorithm simplified by linear approximation (AMP-LA and using the Mean Square Error (MSE criterion to calculate the correlation coefficients between main detector and branch detector for the given iteration. The complexity of our method is compared with other detection algorithms. The simulation results show that our scheme can achieve better performance than the conventional detection methods and have the acceptable complexity.
Robust Transceiver with Tomlinson-Harashima Precoding for Amplify-and-Forward MIMO Relaying Systems
Xing, Chengwen; Gao, Feifei; Wu, Yik-Chung
2011-01-01
In this paper, robust transceiver design with Tomlinson-Harashima precoding (THP) for multi-hop amplify-and-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 estimation errors. 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.
Transceiver Design for Dual-Hop Nonregenerative MIMO-OFDM Relay Systems Under Channel Uncertainties
Xing, Chengwen; Ma, Shaodan; Wu, Yik-Chung; Ng, Tung-Sang
2010-12-01
In this paper, linear transceiver design for dual-hop non-regenerative (amplify-and-forward (AF)) MIMO-OFDM systems under channel estimation errors is investigated. Second order moments of channel estimation errors in the two hops are first deduced. Then based on the Bayesian framework, joint design of linear forwarding matrix at the relay and equalizer at the destination under channel estimation errors is proposed to minimize the total mean-square-error (MSE) of the output signal at the destination. The optimal designs for both correlated and uncorrelated channel estimation errors are considered. The relationship with existing algorithms is also disclosed. Moreover, this design is extended to the joint design involving source precoder design. Simulation results show that the proposed design outperforms the design based on estimated channel state information only.
Robust Transceiver with Tomlinson-Harashima Precoding for Amplify-and-Forward MIMO Relaying Systems
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.
Selective transmission and channel estimation in massive MIMO systems
Institute of Scientific and Technical Information of China (English)
杨睿哲
2016-01-01
Massive MIMO systems have got extraordinary spectral efficiency using a large number of base station antennas, but it is in the challenge of pilot contamination using the aligned pilots.To address this issue, a selective transmission is proposed using time-shifted pilots with cell grouping, where the strong interfering users in downlink transmission cells are temporally stopped during the pilots transmission in uplink cells.Based on the spatial characteristics of physical channel models, the strong interfering users are selected to minimize the inter-cell interference and the cell grouping is designed to have less temporally stopped users within a smaller area.Furthermore, a Kalman estima-tor is proposed to reduce the unexpected effect of residual interferences in channel estimation, which exploits both the spatial-time correlation of channels and the share of the interference information. The numerical results show that our scheme significantly improves the channel estimation accuracy and the data rates.
User Scheduling for Heterogeneous Multiuser MIMO Systems: A Subspace Viewpoint
Yi, Xinping
2011-01-01
In downlink multiuser multiple-input multiple-output (MU-MIMO) systems, users are practically heterogeneous in nature. However, most of the existing user scheduling algorithms are designed with an implicit assumption that the users are homogeneous. In this paper, we revisit the problem by exploring the characteristics of heterogeneous users from a subspace point of view. With an objective of minimizing interference non-orthogonality among users, three new angular-based user scheduling criteria that can be applied in various user scheduling algorithms are proposed. While the first criterion is heuristically determined by identifying the incapability of largest principal angle to characterize the subspace correlation and hence the interference non-orthogonality between users, the second and third ones are derived by using, respectively, the sum rate capacity bounds with block diagonalization and the change in capacity by adding a new user into an existing user subset. Aiming at capturing fairness among heteroge...
Multitarget Identification and Localization Using Bistatic MIMO Radar Systems
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Guisheng Liao
2007-12-01
Full Text Available A scheme for multitarget identification and localization using bistatic MIMO radar systems is proposed. Multitarget can be distinguished by Capon method, as well as the targets angles with respect to transmitter and receiver can be synthesized using the received signals. Thus, the locations of the multiple targets are obtained and spatial synchronization problem in traditional bistatic radars is avoided. The maximum number of targets that can be uniquely identified by proposed method is also analyzed. It is indicated that the product of the numbers of receive and transmit elements minus-one targets can be identified by exploiting the fluctuating of the radar cross section (RCS of the targets. Cramer-Rao bounds (CRB are derived to obtain more insights of this scheme. Simulation results demonstrate the performances of the proposed method using Swerling II target model in various scenarios.
Stiefel Manifold and TCQ based on Unit Memory Coding for MIMO System
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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.
Survey of Channel and Radio Propagation Models for Wireless MIMO Systems
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A. Burr
2007-02-01
Full Text Available This paper provides an overview of the state-of-the-art radio propagation and channel models for wireless multiple-input multiple-output (MIMO systems. We distinguish between physical models and analytical models and discuss popular examples from both model types. Physical models focus on the double-directional propagation mechanisms between the location of transmitter and receiver without taking the antenna configuration into account. Analytical models capture physical wave propagation and antenna configuration simultaneously by describing the impulse response (equivalently, the transfer function between the antenna arrays at both link ends. We also review some MIMO models that are included in current standardization activities for the purpose of reproducible and comparable MIMO system evaluations. Finally, we describe a couple of key features of channels and radio propagation which are not sufficiently included in current MIMO models.
Optimizing the Positioning of MIMO and SISO Systems in Indoor Environments
Bechet, P.; Bouleanu, I.; Neagu, A.; Helbet, R.; Hangan, A.
The adoption of multiple-input multiple-output (MIMO) technologies for the air interface of new wireless communication systems promises to meet the increasing data rate demands of future applications within a reasonable radio bandwidth. MIMO can provide increased spectrum efficiency by exploiting the spatial dimension of the radio wave propagation. The aim of this chapter is to analyze the data transfer capacity in an indoor environment which is relevant for MIMO technology due to its pronounced dispersive character. The performances of individual single-input single-output (SISO), single-input multiple-output (SIMO), multiple-input single-output (MISO), and MIMO communication channels in various scenarios are emphasized in order to identify the optimum positioning of the system components.
Experimental Demonstration of 5-Gb/s Polarization-Multiplexed Fiber-Wireless MIMO Systems
DEFF Research Database (Denmark)
Zhao, Ying; Pang, Xiaodan; Deng, Lei;
2011-01-01
We experimentally demonstrate a 5-Gb/s fiber-wireless transmission system combining optical polarization-division-multiplexing (PDM) and wireless multiple-input, multiple-output (MIMO) spatial multiplexing technologies. The optical-wireless channel throughput is enhanced by achieving a 4b...... advantageous to the MIMO wireless system due to the inter-channel delay insensitivity. The hybrid transmission performance of 26km fiber and up to 2m wireless MIMO is investigated......./s/Hz spectral efficiency. Based on the implementation of constant modulus algorithm (CMA), the 2×2 MIMO wireless channel is characterized and adaptively equalized for signal demodulation. The performance of the CMA-based channel adaptation is studied and it is revealed that the algorithm is particularly...
Survey of Channel and Radio Propagation Models for Wireless MIMO Systems
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Kyösti P
2007-01-01
Full Text Available This paper provides an overview of the state-of-the-art radio propagation and channel models for wireless multiple-input multiple-output (MIMO systems. We distinguish between physical models and analytical models and discuss popular examples from both model types. Physical models focus on the double-directional propagation mechanisms between the location of transmitter and receiver without taking the antenna configuration into account. Analytical models capture physical wave propagation and antenna configuration simultaneously by describing the impulse response (equivalently, the transfer function between the antenna arrays at both link ends. We also review some MIMO models that are included in current standardization activities for the purpose of reproducible and comparable MIMO system evaluations. Finally, we describe a couple of key features of channels and radio propagation which are not sufficiently included in current MIMO models.
Joint Channel and Phase Noise Estimation in MIMO-OFDM Systems
Ngebani, I. M.; Chuma, J. M.; Zibani, I.; Matlotse, E.; Tsamaase, K.
2017-05-01
The combination of multiple-input multiple-output (MIMO) techniques with orthogonal frequency division multiplexing (OFDM), MIMO-OFDM, is a promising way of achieving high spectral efficiency in wireless communication systems. However, the performance of MIMO-ODFM systems is highly degraded by radio frequency (RF) impairments such as phase noise. Similar to the single-input single-output (SISO) case, phase noise in MIMO-OFDM systems results in a common phase error (CPE) and inter carrier interference (ICI). In this paper the problem of joint channel and phase noise estimation in a system with multiple transmit and receive antennas where each antenna is equipped with its own independent oscillator is tackled. The technique employed makes use of a novel placement of pilot carriers in the preamble and data portion of the MIMO-OFDM frame. Numerical results using a 16 and 64 quadrature amplitude modulation QAM schemes are provided to illustrate the effectiveness of the proposed scheme for MIMO-OFDM systems.
An Enhanced Leakage-Based Precoding Scheme for Multi-User Multi-Layer MIMO Systems
Yang, Chunliang
2014-01-01
In this paper, we propose an enhanced leakage-based precoding scheme, i.e., layer signal to leakage plus noise ratio (layer SLNR) scheme, for multi-user multi-layer MIMO systems. Specifically, the layer SLNR scheme incorporates the MIMO receiver structure into the precoder design procedure, which makes the formulation of signal power and interference / leakage power more accurate. Besides, the layer SLNR scheme not only takes into account the inter-layer interference from different users, but...
Cao, Pan; Jorswieck, Eduard A.; Shi, Shuying
2013-10-01
We consider a multiple-input multiple-output (MIMO) interference channel (IC), where a single data stream per user is transmitted and each receiver treats interference as noise. The paper focuses on the open problem of computing the outermost boundary (so-called Pareto boundary-PB) of the achievable rate region under linear transceiver design. The Pareto boundary consists of the strict PB and non-strict PB. For the two user case, we compute the non-strict PB and the two ending points of the strict PB exactly. For the strict PB, we formulate the problem to maximize one rate while the other rate is fixed such that a strict PB point is reached. To solve this non-convex optimization problem which results from the hard-coupled two transmit beamformers, we propose an alternating optimization algorithm. Furthermore, we extend the algorithm to the multi-user scenario and show convergence. Numerical simulations illustrate that the proposed algorithm computes a sequence of well-distributed operating points that serve as a reasonable and complete inner bound of the strict PB compared with existing methods.
The Performance Analysis of PAPR Reduction using a novel PTS technique in OFDM-MIMO System
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Kashish Sareen
2012-08-01
Full Text Available Orthogonal Frequency Division Multiplexing (OFDM is an new multiplexing technique for 4G and 4.5G generation wireless communication. MIMO-OFDM is latest multiplexing technique which is resposible for high performance 4G broadband wireless communications. But there is one main disadvantage of MIMO-OFDM is the high peak-to-average power ratio (PAPR of the transmitter’s output signal on different antennas. In this paper, we present a new noble (PTS Partial transmit sequence technique to reduce PAPR problem in OFDM-MIMO system. This new PTS technique gives us better PAPR Reduction gain in OFDM-MIMO as compared with original and another PTS Techniques.
OFDM与MIMO-OFDM系统中PAPR问题研究%Research on PAPR in OFDM and MIMO-OFDM Systems
Institute of Scientific and Technical Information of China (English)
董少强; 张纳温; 岳韶华; 胡茂凯
2010-01-01
正交频分复用(OFDM)和MIMO-OFDM技术都存在高峰均比的问题,大多数方法都是把降低OFDM峰均比的方法直接使用MIMO-OFDM系统,但在与MIMO-OFDM系统的匹配上存在较大问题.分析了OFDM和MIMO-OFDM的系统模型及PAPR,从理论上分析了OFDM和MIMO-OFDM两系统的关系,给出了在MIMO-OFDM系统中降低PAPR需要注意的问题,为OFDM和MIMO-OFDM系统的技术实用化做好理论基础.
Performance Analysis of Cooperative Virtual MIMO Systems for Wireless Sensor Networks
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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.
Performance Analysis of Cooperative Virtual MIMO Systems for Wireless Sensor Networks
Rafique, Zimran; Seet, Boon-Chong; Al-Anbuky, Adnan
2013-01-01
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. PMID:23760087
Investigating the Impact of Hybrid/SPREAD MIMO-OFDM System for Spectral-Efficient Wireless Networks
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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.
MIMO model of an interacting series process for Robust MPC via System Identification.
Wibowo, Tri Chandra S; Saad, Nordin
2010-07-01
This paper discusses the empirical modeling using system identification technique with a focus on an interacting series process. The study is carried out experimentally using a gaseous pilot plant as the process, in which the dynamic of such a plant exhibits the typical dynamic of an interacting series process. Three practical approaches are investigated and their performances are evaluated. The models developed are also examined in real-time implementation of a linear model predictive control. The selected model is able to reproduce the main dynamic characteristics of the plant in open-loop and produces zero steady-state errors in closed-loop control system. Several issues concerning the identification process and the construction of a MIMO state space model for a series interacting process are deliberated.
Queue-Aware Distributive Resource Control for Delay-Sensitive Two-Hop MIMO Cooperative Systems
Wang, Rui; Cui, Ying
2010-01-01
In this paper, we consider a queue-aware distributive resource control algorithm for two-hop MIMO cooperative systems. We shall illustrate that relay buffering is an effective way to reduce the intrinsic half-duplex penalty in cooperative systems. The complex interactions of the queues at the source node and the relays are modeled as an average-cost infinite horizon Markov Decision Process (MDP). The traditional approach solving this MDP problem involves centralized control with huge complexity. To obtain a distributive and low complexity solution, we introduce a linear structure which approximates the value function of the associated Bellman equation by the sum of per-node value functions. We derive a distributive two-stage two-winner auction-based control policy which is a function of the local CSI and local QSI only. Furthermore, to estimate the best fit approximation parameter, we propose a distributive online stochastic learning algorithm using stochastic approximation theory. Finally, we establish techn...
On Transmit Antenna Selection for Multiuser MIMO Systems with Dirty Paper Coding
Mohaisen, Manar
2010-01-01
In this paper, we address the transmit antenna selection in multi-user MIMO systems with precoding. The optimum and reduced complexity sub-optimum antenna selection algorithms are introduced. QR-decomposition (QRD) based antenna selection is investigated and the reason behind its sub-optimality is analytically derived. We introduce the conventional QRD-based algorithm and propose an efficient QRD-based transmit antenna scheme (maxR) that is both implementation and performance efficient. Moreover, we derive explicit formulae for the computational complexities of the aforementioned algorithms. Simulation results and analysis demonstrate that the proposed maxR algorithm requires only 1% of the computational efforts required by the optimal algorithm for a degradation of 1dB and 0.1dB in the case of linear zero-forcing and Tomlinson-Harashima precoding schemes, respectively.
Joint timing synchronization and frequency offset acquisition algorithm for MIMO OFDM systems
Institute of Scientific and Technical Information of China (English)
Liu Qi; Hu Bo
2009-01-01
For multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) sys-tems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform (FRFT) is proposed. The linear frequency modulation signals superimposed on the data signals are used as the training signals. By performing FRFT on the receiver signals and searching the peak value of the FRFT results, the receiver can realize timing synchronization and frequency offset acquisition simultaneously. Compared with the existing methods, the proposed algorithm can provide better timing synchronization performance and larger frequency offset acquisition range even under multi-path channels with low signal to noise ratio. Theoretical analysis and simulation results prove this point.
MimoSA: a system for minimotif annotation
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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
Performance of Adaptive Subchannel Assignment-Based MIMO/OFDM Systems over Multipath Fading Channels
Institute of Scientific and Technical Information of China (English)
无
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.
Energy-Efficient Power Allocation for MIMO-SVD Systems
Sboui, Lokman
2017-05-24
In this paper, we address the problem of energyefficient power allocation in MIMO systems. In fact, the widely adopted water-filling power allocation does not ensure the maximization of the energy efficiency (EE). Since the EE maximization is a non-convex problem, numerical methods based on fractional programming were introduced to find the optimal power solutions. In this paper, we present a novel and simple power allocation scheme based on the explicit expressions of the optimal power. We also present a low-complexity algorithm that complements the proposed scheme for low circuit-power regime. Furthermore, we analyze power-constrained and rate-constrained systems and present the corresponding optimal power control. In the numerical results, we show that the presented analytical expressions are accurate and that the algorithm converges within two iterations. We also show that as the number of antenna increases, the system becomes more energy-efficient. Also, a saturation of the EE is observed at high power budget and low minimal rate regimes.
Directory of Open Access Journals (Sweden)
Christina Gimmler-Dumont
2012-01-01
reliability information is fed back from the channel decoder to the MIMO detector. In this paper, we derive a basic framework to compare different soft-input soft-output MIMO detectors in open- and closed-loop systems. Within this framework, we analyze a depth-first sphere detector and a breadth-first fixed effort detector for different application scenarios and their effects on area and energy efficiency on the whole system. We present all system components under open- and closed-loop system aspects and determine the overall implementation cost for changing an open-loop system in a closed-loop system.
MIMO 构架 LDPC －COFDM应急通信系统研究%MIMO Structure LDPC-COFDM Emergency Communication System Research
Institute of Scientific and Technical Information of China (English)
贾志城
2016-01-01
To explore the MIMO technology , LDPC-COFDM technology principle as the breakthrough point , deeply analyzing the MIMO structure of LDPC -COFDM breakthrough advantages of mobile communication system , its exceptional performance with bilateral advantages of MIMO and OFDM system performance , can form the spectrum Labour than high efficiency , low error rate and high efficiency of data transmission charac-teristics for the integration of new mobile communication system , suitable for emergency communication net-work and strong mobile real -time applications .%以探究 MIMO 技术、LDPC －COFDM 技术原理为切入点，分析采用 MIMO 构架的 LDPC －COFDM移动通信系统的突破性优势，其性能具有MIMO系统和OFDM系统性能的双边优势，能够形成全新的移动通信系统，适合于应急通信组网和实时性较强的移动应用。
RF Lens-Embedded Massive MIMO Systems: Fabrication Issues and Codebook Design
Kwon, Taehoon; Lim, Yeon-Geun; Min, Byung-Wook; Chae, Chan-Byoung
2016-07-01
In this paper, we investigate a radio frequency (RF) lens-embedded massive multiple-input multiple-output (MIMO) system and evaluate the system performance of limited feedback by utilizing a technique for generating a suitable codebook for the system. We fabricate an RF lens that operates on a 77 GHz (mmWave) band. Experimental results show a proper value of amplitude gain and an appropriate focusing property. In addition, using a simple numerical technique--beam propagation method (BPM)--we estimate the power profile of the RF lens and verify its accordance with experimental results. We also design a codebook--multi-variance codebook quantization (MVCQ)--for limited feedback by considering the characteristics of the RF lens antenna for massive MIMO systems. Numerical results confirm that the proposed system shows significant performance enhancement over a conventional massive MIMO system without an RF lens.
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Meenakshi
2016-07-01
Full Text Available MIMO-OFDM is an attractive interface for the next generation WLANs, WMAN, 4G and 5G mobile cellular systems. However the performance of the MIMO-OFDM systems is affected by Peak to Average Power Ratio (PAPR. PAPR is the main disadvantage associated with the MIMO-OFDM systems. So far, many techniques have been proposed to reduce the value of PAPR but high PAPR for MIMO-OFDM systems is still a demanding area and a different issue.In this paper, a hybrid VLM precoded SLM scheme using Clipping & Filtering has been proposed to reduce PAPR in MIMO-OFDM systems. And it has been observed that the proposed scheme has achieved a significant gain in PAPR reduction without increasing the system complexity and affecting the error performance of the system
EVALUATION OF BER FOR VARIOUS FADING CHANNEL IN DWT BASED MIMO-OFDM SYSTEM
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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.
Optimal Channel Training in Uplink Network MIMO Systems
Hoydis, Jakob; Debbah, Merouane
2011-01-01
We consider a multi-cell frequency-selective fading uplink channel (network MIMO) from K single-antenna user terminals (UTs) to B cooperative base stations (BSs) with M antennas each. The BSs, assumed to be oblivious of the applied codebooks, forward compressed versions of their observations to a central station (CS) via capacity limited backhaul links. The CS jointly decodes the messages from all UTs. Since the BSs and the CS are assumed to have no prior channel state information (CSI), the channel needs to be estimated during its coherence time. Based on a lower bound of the ergodic mutual information, we determine the optimal fraction of the coherence time used for channel training, taking different path losses between the UTs and the BSs into account. We then study how the optimal training length is impacted by the backhaul capacity. Although our analytical results are based on a large system limit, we show by simulations that they provide very accurate approximations for even small system dimensions.
Sifaou, Houssem
2016-05-01
Massive MIMO systems are shown to be a promising technology for next generations of wireless communication networks. The realization of the attractive merits promised by massive MIMO systems requires advanced linear precoding and receiving techniques in order to mitigate the interference in downlink and uplink transmissions. This work considers the precoder and receiver design in massive MIMO systems. We first consider the design of the linear precoder and receiver that maximize the minimum signal-to-interference-plus-noise ratio (SINR) subject to a given power constraint. The analysis is carried out under the asymptotic regime in which the number of the BS antennas and that of the users grow large with a bounded ratio. This allows us to leverage tools from random matrix theory in order to approximate the parameters of the optimal linear precoder and receiver by their deterministic approximations. Such a result is of valuable practical interest, as it provides a handier way to implement the optimal precoder and receiver. To reduce further the complexity, we propose to apply the truncated polynomial expansion (TPE) concept on a per-user basis to approximate the inverse of large matrices that appear on the expressions of the optimal linear transceivers. Using tools from random matrix theory, we determine deterministic approximations of the SINR and the transmit power in the asymptotic regime. Then, the optimal per-user weight coe cients that solve the max-min SINR problem are derived. The simulation results show that the proposed precoder and receiver provide very close to optimal performance while reducing signi cantly the computational complexity. As a second part of this work, the TPE technique in a per-user basis is applied to the optimal linear precoding that minimizes the transmit power while satisfying a set of target SINR constraints. Due to the emerging research eld of green cellular networks, such a problem is receiving increasing interest nowadays. Closed
Compensation for HPA nonlinearity and I/Q imbalance in MIMO beamforming systems
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.
Power efficient low complexity precoding for massive MIMO systems
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.
Interference Alignment and Fairness Algorithms for MIMO Cognitive Radio Systems
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Feng Zhao
2015-01-01
Full Text Available Interference alignment (IA is an effective technique to eliminate the interference among wireless nodes. In a multiinput multi-output (MIMO cognitive radio system, multiple secondary users can coexist with the primary user without generating any interference by using the IA technology. However, few works have considered the fairness of secondary users. In this paper, not only is the interference eliminated by IA, but also the fairness of secondary users is considered by two kinds of algorithms. Without losing generality, one primary user and K secondary users are considered in the network. Assuming perfect channel knowledge at the primary user, the interference from secondary users to the primary user is aligned into the unused spatial dimension which is obtained by water-filling among primary user. Also, the interference between secondary users can be eliminated by a modified maximum signal-to-interference-plus-noise algorithm using channel reciprocity. In addition, two kinds of fairness algorithms, max-min fairness and proportional fairness, among secondary users are proposed. Simulation results show the effectiveness of the proposed algorithms in terms of suppressed interference and fairness of secondary nodes. What is more, the performances of the two fairness algorithms are compared.
A Reconfigurable Spiral Antenna for Adaptive MIMO Systems
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Qian JY
2005-01-01
Full Text Available We present a reconfigurable spiral antenna for use in adaptive MIMO systems. The antenna is capable of changing the sense of polarization of the radiated field. It is fabricated by using an RF-MEMS technology compatible with microwave laminate substrates developed within the author's group. The proposed antenna structure is built on a number of rectangular-shaped bent metallic strips interconnected to each other with RF-MEMS actuators. Two senses of polarization, RHCP and LHCP, are achieved by configuring the physical structure of the antenna, that is, by changing the winding sense of the spiral, through judicious activation of MEM actuators. The fabrication process for the monolithic integration of MEM actuators with bent microstrip pixels on RO4003-FR4 microwave laminate substrate is described. The measured and calculated radiation and impedance characteristics of the antenna are given. The operating frequency of the presented antenna design can easily be adjusted to be compatible with popular IEEE networking standards such as 802.11a.
A Reconfigurable Spiral Antenna for Adaptive MIMO Systems
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Cetiner Bedri A.
2005-01-01
Full Text Available We present a reconfigurable spiral antenna for use in adaptive MIMO systems. The antenna is capable of changing the sense of polarization of the radiated field. It is fabricated by using an RF-MEMS technology compatible with microwave laminate substrates developed within the author's group. The proposed antenna structure is built on a number of rectangular-shaped bent metallic strips interconnected to each other with RF-MEMS actuators. Two senses of polarization, RHCP and LHCP, are achieved by configuring the physical structure of the antenna, that is , by changing the winding sense of the spiral, through judicious activation of MEM actuators. The fabrication process for the monolithic integration of MEM actuators with bent microstrip pixels on RO4003-FR4 microwave laminate substrate is described. The measured and calculated radiation and impedance characteristics of the antenna are given. The operating frequency of the presented antenna design can easily be adjusted to be compatible with popular IEEE networking standards such as 802.11a.
Resetting AUDI Algorithm Used in Rapid Time-varying MIMO System Identification
Institute of Scientific and Technical Information of China (English)
Xu Chao(许超); Chen Zhigang; Shao Huihe
2004-01-01
Augmented UD identification (AUDI) technique is derived from the traditional recursive least-squares (RLS) algorithm and has been developed rapidly during the last decade. AUDI is a cluster of identification algorithms based on matrix factorization methods (such as QR and LDL) and thus shows its stable performance in system identification applications. An AUDI algorithm with resetting strategy (RAUDI) has much ability in rapid time-varying SISO system identification. In this paper, an endeavor to expand the RAUDI in MIMO system identification is made and a comparative experiement is done to exhibit its good ability in rapidly changing parameter estimate in MIMO system.
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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.
Diversity and MIMO Performance Evaluation of Common Phase Center Multi Element Antenna Systems
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V. Papamichael
2008-06-01
Full Text Available The diversity and Multiple Input Multiple Output (MIMO performance provided by common phase center multi element antenna (CPCMEA systems is evaluated using two practical methods which make use of the realized active element antenna patterns. These patterns include both the impact of the mutual coupling and the mismatch power loss at antenna ports. As a case study, two and four printed Inverted F Antenna (IFA systems are evaluated by means of Effective Diversity Gain (EDG and Capacity (C. EDG is measured in terms of the signal-to-noise ratio (SNR enhancement at a specific outage probability and in terms of the SNR reduction for achieving a desired average bit error rate (BER. The concept of receive antenna selection in MIMO systems is also investigated and the simulation results show a 43% improvement in the 1% outage C of a reconfigurable 2x2 MIMO system over a fixed 2x2 one.
Bai, Lin; Yu, Quan
2014-01-01
Multiple-input multiple-output (MIMO) systems can increase the spectral efficiency in wireless communications. However, the interference becomes the major drawback that leads to high computational complexity at both transmitter and receiver. In particular, the complexity of MIMO receivers can be prohibitively high. As an efficient mathematical tool to devise low complexity approaches that mitigate the interference in MIMO systems, lattice reduction (LR) has been widely studied and employed over the last decade. The co-authors of this book are world's leading experts on MIMO receivers, and here they share the key findings of their research over years. They detail a range of key techniques for receiver design as multiple transmitted and received signals are available. The authors first introduce the principle of signal detection and the LR in mathematical aspects. They then move on to discuss the use of LR in low complexity MIMO receiver design with respect to different aspects, including uncoded MIMO detection...
A new approach for inversion of large random matrices in massive MIMO systems.
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Muhammad Ali Raza Anjum
Full Text Available We report a novel approach for inversion of large random matrices in massive Multiple-Input Multiple Output (MIMO systems. It is based on the concept of inverse vectors in which an inverse vector is defined for each column of the principal matrix. Such an inverse vector has to satisfy two constraints. Firstly, it has to be in the null-space of all the remaining columns. We call it the null-space problem. Secondly, it has to form a projection of value equal to one in the direction of selected column. We term it as the normalization problem. The process essentially decomposes the inversion problem and distributes it over columns. Each column can be thought of as a node in the network or a particle in a swarm seeking its own solution, the inverse vector, which lightens the computational load on it. Another benefit of this approach is its applicability to all three cases pertaining to a linear system: the fully-determined, the over-determined, and the under-determined case. It eliminates the need of forming the generalized inverse for the last two cases by providing a new way to solve the least squares problem and the Moore and Penrose's pseudoinverse problem. The approach makes no assumption regarding the size, structure or sparsity of the matrix. This makes it fully applicable to much in vogue large random matrices arising in massive MIMO systems. Also, the null-space problem opens the door for a plethora of methods available in literature for null-space computation to enter the realm of matrix inversion. There is even a flexibility of finding an exact or approximate inverse depending on the null-space method employed. We employ the Householder's null-space method for exact solution and present a complete exposition of the new approach. A detailed comparison with well-established matrix inversion methods in literature is also given.
A new approach for inversion of large random matrices in massive MIMO systems.
Anjum, Muhammad Ali Raza; Ahmed, Muhammad Mansoor
2014-01-01
We report a novel approach for inversion of large random matrices in massive Multiple-Input Multiple Output (MIMO) systems. It is based on the concept of inverse vectors in which an inverse vector is defined for each column of the principal matrix. Such an inverse vector has to satisfy two constraints. Firstly, it has to be in the null-space of all the remaining columns. We call it the null-space problem. Secondly, it has to form a projection of value equal to one in the direction of selected column. We term it as the normalization problem. The process essentially decomposes the inversion problem and distributes it over columns. Each column can be thought of as a node in the network or a particle in a swarm seeking its own solution, the inverse vector, which lightens the computational load on it. Another benefit of this approach is its applicability to all three cases pertaining to a linear system: the fully-determined, the over-determined, and the under-determined case. It eliminates the need of forming the generalized inverse for the last two cases by providing a new way to solve the least squares problem and the Moore and Penrose's pseudoinverse problem. The approach makes no assumption regarding the size, structure or sparsity of the matrix. This makes it fully applicable to much in vogue large random matrices arising in massive MIMO systems. Also, the null-space problem opens the door for a plethora of methods available in literature for null-space computation to enter the realm of matrix inversion. There is even a flexibility of finding an exact or approximate inverse depending on the null-space method employed. We employ the Householder's null-space method for exact solution and present a complete exposition of the new approach. A detailed comparison with well-established matrix inversion methods in literature is also given.
Reduced complexity and latency for a massive MIMO system using a parallel detection algorithm
Directory of Open Access Journals (Sweden)
Shoichi Higuchi
2017-09-01
Full Text Available In recent years, massive MIMO systems have been widely researched to realize high-speed data transmission. Since massive MIMO systems use a large number of antennas, these systems require huge complexity to detect the signal. In this paper, we propose a novel detection method for massive MIMO using parallel detection with maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD to reduce the complexity and latency. The proposed scheme obtains an R matrix after permutation of an H matrix and QR decomposition. The R matrix is also eliminated using a Gauss–Jordan elimination method. By using a modified R matrix, the proposed method can detect the transmitted signal using parallel detection. From the simulation results, the proposed scheme can achieve a reduced complexity and latency with a little degradation of the bit error rate (BER performance compared with the conventional method.
Directory of Open Access Journals (Sweden)
Feng Zhao
2015-01-01
Full Text Available Multi-input multioutput (MIMO technique provides a promising solution to enhance the performance of wireless communication systems. In this paper, we consider antenna correlation at the transmitter in practical cognitive MIMO systems. What is more, a game-theoretic framework is conducted to analyze the optimum beamforming and power allocation such that each user maximizes its own rate selfishly under the transmitting power constraint and the primary user (PU interference constraint. The design of the cognitive MIMO system is formulated as a noncooperative game, where the secondary users (SUs compete with each other over the resources made available by the PUs. Interestingly, as the correlation parameter grows, the utility degrades. Nash equilibrium is considered as the solution of this game. Simulation results show that the proposed algorithm can converge quickly and clearly outperforms the strategy without game.
A novel mirror diversity receiver for indoor MIMO visible light communication systems
Park, Kihong
2016-12-24
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 × 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.
Improved AGC method for B3G MIMO-OFDM system
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Automatic gain control (AGC) has an important role in multi-input multi-output-orthogonal frequency-division multiplexing (MIMO-OFDM) system, especially, when receiving antennas are distributed.In recent years, much work has been done on efficiency and simplification of AGC, but few of them are aiming at multiple antennas.This article, on the assumption of ideal AGC for single receiving antenna, analyzes feasible AGC methods for MIMO system from a new aspect, then brings forward three applicable AGC methods: separate automatic gain control, joint automatic gain control, and partly-joint automatic gain control (PJ-AGC).After simulation, when parameters are properly set, PJ-AGC has the best performance and can be applied to B3G MIMO-OFDM system.
On the BER and capacity analysis of MIMO MRC systems with channel estimation error
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.
Blind Carrier Frequency Offset Estimation via Power Spectrum Analysis in MIMO OFDM Systems
Institute of Scientific and Technical Information of China (English)
WU Lu; ZHANG Xianda
2009-01-01
As a generalization of orthogonal frequency-division multiplexing (OFDM) systems,multi-input multi-output (MIMO) OFDM systems are very sensitive to carrier frequency offset (CFO).This paper proposes a blind CFO estimation method based on power spectrum analysis,which has high bandwidth efficiency and is much less complex.This method can be used to estimate the residual CFO,which is less than half of the subcarrier spacing.The method uses a cosine cost function to get a closed-form CFO estimate.Simulation results illustrate that the method is effective for MIMO OFDM systems.
Uplink Downlink Rate Balancing and Throughput Scaling in FDD Massive MIMO Systems
Bergel, Itsik; Perets, Yona; Shamai, Shlomo
2016-05-01
In this work we extend the concept of uplink-downlink rate balancing to frequency division duplex (FDD) massive MIMO systems. We consider a base station with large number antennas serving many single antenna users. We first show that any unused capacity in the uplink can be traded off for higher throughput in the downlink in a system that uses either dirty paper (DP) coding or linear zero-forcing (ZF) precoding. We then also study the scaling of the system throughput with the number of antennas in cases of linear Beamforming (BF) Precoding, ZF Precoding, and DP coding. We show that the downlink throughput is proportional to the logarithm of the number of antennas. While, this logarithmic scaling is lower than the linear scaling of the rate in the uplink, it can still bring significant throughput gains. For example, we demonstrate through analysis and simulation that increasing the number of antennas from 4 to 128 will increase the throughput by more than a factor of 5. We also show that a logarithmic scaling of downlink throughput as a function of the number of receive antennas can be achieved even when the number of transmit antennas only increases logarithmically with the number of receive antennas.
Fixed-complexity Sphere Encoder for Multi-user MIMO Systems
Mohaisen, Manar
2011-01-01
In this paper, we propose a fixed-complexity sphere encoder (FSE) for multi-user MIMO (MU-MIMO) systems. The proposed FSE accomplishes a scalable tradeoff between performance and complexity. Also, because it has a parallel tree-search structure, the proposed encoder can be easily pipelined, leading to a tremendous reduction in the precoding latency. The complexity of the proposed encoder is also analyzed, and we propose two techniques that reduce it. Simulation and analytical results demonstrate that in a 4 by 4 MU-MIMO system, the proposed FSE requires only 11.5% of the computational complexity needed by the conventional QRD-M encoder (QRDM-E). Also, the encoding throughput of the proposed encoder is 7.5 times that of the QRDM-E with tolerable degradation in the BER performance, while achieving the optimum diversity order.
Vasyuta, K. S.; Zakharchenko, I. V.; Ozerov, S. V.
2015-01-01
The paper discusses the expediency of using MIMO digital systems for transmission of chaotic signals as a way of partial solution of electromagnetic compatibility of perspective broadband communication systems with an existing class of narrow-band radio-technical systems.
An adaptive fuzzy design for fault-tolerant control of MIMO nonlinear uncertain systems
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
This paper presents a novel control method for accommodating actuator faults in a class of multiple-input multiple-output (MIMO) nonlinear uncertain systems.The designed control scheme can tolerate both the time-varying lock-in-place and loss of effectiveness actuator faults.In each subsystem of the considered MIMO system,the controller is obtained from a backstepping procedure;an adaptive fuzzy approximator with minimal learning parameterization is employed to approximate the package of unknown nonlinear f...
On Blind MIMO System Identification Based on Second-Order Cyclic Statistics
Directory of Open Access Journals (Sweden)
K. Sabri
2008-01-01
Full Text Available This letter introduces a new frequency domain approach for either MIMO System Identification or Source Separation of convolutive mixtures in cyclostationary context. We apply the joint diagonalization algorithm to a set of cyclic spectral density matrices of the measurements to identify the mixing system at each frequency up to permutation and phase ambiguity matrices. An efficient algorithm to overcome the frequency dependent permutations and to recover the phase, even for non-minimum-phase channels, based on cyclostationarity is also presented. The new approach exploits the fact that each input has a different and specific cyclic frequency. A comparison with an existing MIMO method is proposed.
A Simulation Study on Channel Estimation for MIMO-OFDM Based Beyond 3G Mobile Systems
Institute of Scientific and Technical Information of China (English)
YIN Chang-chuan; ZHAO Xue-yuan; HOU Xiao-lin; YUE Guang-xin
2005-01-01
Multi-Input Multi-Output antennas based Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) has been chosen as the air interface technology for China's beyond 3G Time-Division Duplex (TDD) mobile system in the FuTURE research project. Channel estimation plays a key role on the performance of the MIMO-OFDM receiver. In this paper, we present five channel estimation algorithms and study their performance in a simulated beyond 3G TDD mobile system. Simulation results show that the adaptive 2D-LMS algorithm we proposed recently has the best performance when the signal to noise ratio is lower than 8 dB.
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 relations...
A Comparative Analysis of LS and MMSE Channel Estimation Techniques for MIMO-OFDM System
Directory of Open Access Journals (Sweden)
Avinash Sahu
2014-06-01
Full Text Available Multiple transmit and receive antennas can be used to form multiple-input multiple-output (MIMO channels to increase the capacity by a factor of the minimum number of transmit and receive antennas. In this paper, orthogonal frequency division multiplexing (OFDM for MIMO channels (MIMO-OFDM is considered for wideband transmission to mitigate intersymbol interference and enhance system capacity. In this paper performance analysis of channel estimation through different algorithms for estimating channel using BPSK modulation scheme are investigated for different channel delay spread. The estimation of channel at pilot frequencies is based on Least Square, Minimum mean square channel estimation algorithm. We have compared the performances of these two channel estimation algorithm by measuring bit error rate Vs SNR. Minimum Mean Square estimation has been shown to perform much better than Least Square channel estimation algorithm.
Institute of Scientific and Technical Information of China (English)
高伟东; 王文博; 程昱; 彭木根; 张欢
2009-01-01
该文研究了在中继站已知完全信道信息或统计信道信息情况下的多输入多输出(MIMO)中继系统收发信机设计的问题.中继站利用获得的信道状态信息对接收信号进行滤波转发,接收节点采用线性最小均方误差接收机(MMSE)恢复出原始信号.仿真结果表明,所提中继转发策略性能优于传统的放大转发.在高信噪比条件下,基于部分信道状态信息反馈的设计方案可以获得与完全信道状态信息反馈接近的性能.
Suppression of EM Fields using Active Control Algorithms and MIMO Antenna System
Directory of Open Access Journals (Sweden)
A. Mohammed
2004-09-01
Full Text Available Active methods for attenuating acoustic pressure fields have beensuccessfully used in many applications. In this paper we investigatesome of these active control methods in combination with a MIMO antennasystem in order to assess their validity and performance when appliedto electromagnetic fields. The application that we evaluated in thispaper is a model of a mobile phone equipped with one ordinarytransmitting antenna and two actuator-antennas which purpose is toreduce the electromagnetic field at a specific area in space (e.g. atthe human head. Simulation results show the promise of using theadaptive active control algorithms and MIMO system to attenuate theelectromagnetic field power density.
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.
Directory of Open Access Journals (Sweden)
Houda Salhi
2016-01-01
Full Text Available This paper deals with the parameter estimation problem for multivariable nonlinear systems described by MIMO state-space Wiener models. Recursive parameters and state estimation algorithms are presented using the least squares technique, the adjustable model, and the Kalman filter theory. The basic idea is to estimate jointly the parameters, the state vector, and the internal variables of MIMO Wiener models based on a specific decomposition technique to extract the internal vector and avoid problems related to invertibility assumption. The effectiveness of the proposed algorithms is shown by an illustrative simulation example.
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.
Precoding Design for Single-RF Massive MIMO Systems: A Large System Analysis
Sifaou, Houssem
2016-08-26
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 the recently proposed single radio frequency (RF) MIMO transmitter 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 precoder for more involved channels accounting for spatial correlation. The obtained expressions are then optimized in order to maximize the signalto- interference-plus-noise ratio (SINR). Simulation results are provided in order to illustrate the performance of the optimized precoder in terms of peak-to-average power ratio (PAPR) and signal-to-interference-plus-noise ratio (SINR). © 2012 IEEE.
分布式MIMO系统最优功率分配容量分析%Capacity Analysis of Optimal Power Allocation in Distributed MIMO Systems
Institute of Scientific and Technical Information of China (English)
王树坤; 高向川; 王忠勇; 路新华; 董素鸽
2015-01-01
大规模分布式MIMO( Distributed Multiple-Input Multiple-Output,D-MIMO)系统的性能不仅受到小尺度瑞利衰落的影响,而且还受到路径损耗的影响,系统的容量分析存在一定的困难。目前容量分析多以天线等功率分配为主。基于信道统计信息,结合线性排列天线的结构特点,针对大规模分布式MIMO功率优化后的容量性能进行分析,提出一种最优功率分配方案。与传统的等功率分配方案相比,最优功率分配方案可以使分布式MIMO系统的容量获得较大提升。%The performance of D-MIMO ( Massive Distribute Multiple-Input Multiple-Output) systems is affected not only by small-scale Rayleigh fading but also by path loss. There exist certain difficulties in an-alyzing the capacity of Massive D-MIMO systems. At present, plenty of system capacity analysis focuses on equal power allocation of each transmission antenna. Based on CSI (Channel Statistics Information), the structure of linear antennas, and the capacity analysis of the system with optimal power allocation, an optimal power allocation scheme is proposed. Comparison with the traditional equal power allocation indi-cates that the optimal power allocation scheme could evidently increase the capacity of D-MIMO system.
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.
Quantification of MDL-induced signal degradation in MIMO-OFDM mode-division multiplexing systems.
Tian, Yu; Li, Juhao; Zhu, Paikun; Wu, Zhongying; Chen, Yuanxiang; He, Yongqi; Chen, Zhangyuan
2016-08-22
Mode-division multiplexing (MDM) transmission over few-mode optical fiber has emerged as a promising technology to enhance transmission capacity, in which multiple-input-multiple-output (MIMO) digital signal processing (DSP) after coherent detection is used to demultiplex the signals. Compared with conventional single-mode systems, MIMO-MDM systems suffer non-recoverable signal degradation induced by mode-dependent loss (MDL). In this paper, the MDL-induced signal degradation in orthogonal-frequency-division-multiplexing (OFDM) MDM systems is theoretically quantified in terms of mode-average error vector magnitude (EVM) through frequency domain norm analysis. A novel scalar MDL metric is proposed considering the probability distribution of the practical MDM input signals, and a closed-form expression for EVM measured after zero-force (ZF) MIMO equalization is derived. Simulation results show that the EVM estimations utilizing the novel MDL metric remain unbiased for unrepeated links. For a 6 × 100 km 20-mode MDM transmission system, the estimation accuracy is improved by more than 90% compared with that utilizing traditional condition number (CN) based MDL metric. The proposed MDL metric can be used to predict the MDL-induced SNR penalty in a theoretical manner, which will be beneficial for the design of practical MIMO-MDM systems.
LINEAR SYSTEMS AND LINEAR INTERPOLATION I
Institute of Scientific and Technical Information of China (English)
丁立峰
2001-01-01
he linear interpolation of linear system on a family of linear systems is introduced and discussed. Some results and examples on singly generated systems on a finite dimensional vector space are given.
BER performance analysis of OFDM-MIMO system using GNU Radio
Directory of Open Access Journals (Sweden)
Singh M.Ushamahesh
2016-01-01
Full Text Available Multiple Input Multiple Output (MIMO channels can be used to increase the data rate and the channel capacity by employing multiple transmitting and receiving antennas at both the ends of a wireless communication system. MIMO systems employ Orthogonal Frequency Division Multiplexing (OFDM technique and it uses separate antennas at both the transmitter and receiver to increase the data rate and with OFDM, instead of a single carrier, the main information is modulated into a number of independent sub-carrier signals which are orthogonal to each other. This paper presents an OFDM-MIMO transceiver design and the performance analysis of the system based on Error rate for different modulation techniques using GNU Radio. OFDM is chosen over a single carrier solution due to lower complexity of equalizers for high delay spread channels or high data rates. So the combination of MIMO-OFDM system has become a potential technology for high speed data transmission and efficient utilization of the channel spectrum for the modern wireless communication networks.
Multi-user MIMO and carrier aggregation in 4G systems
DEFF Research Database (Denmark)
Cattoni, Andrea Fabio; Nguyen, Hung Tuan; Duplicy, Jonathan
2012-01-01
innovative techniques in the area of MU-MIMO and CA with particular focus on the practical, real-life, implementation and system deployment aspects. In the present paper, we provided an overview of the up-to-date SAMURAI contributions together with a description of the SAMURAI demonstrators developed as core...
RF Transceiver Design for MIMO Wireless Communications
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...
Distributed Compressive CSIT Estimation and Feedback for FDD Multi-User Massive MIMO Systems
Rao, Xiongbin; Lau, Vincent K. N.
2014-06-01
To fully utilize the spatial multiplexing gains or array gains of massive MIMO, the channel state information must be obtained at the transmitter side (CSIT). However, conventional CSIT estimation approaches are not suitable for FDD massive MIMO systems because of the overwhelming training and feedback overhead. In this paper, we consider multi-user massive MIMO systems and deploy the compressive sensing (CS) technique to reduce the training as well as the feedback overhead in the CSIT estimation. The multi-user massive MIMO systems exhibits a hidden joint sparsity structure in the user channel matrices due to the shared local scatterers in the physical propagation environment. As such, instead of naively applying the conventional CS to the CSIT estimation, we propose a distributed compressive CSIT estimation scheme so that the compressed measurements are observed at the users locally, while the CSIT recovery is performed at the base station jointly. A joint orthogonal matching pursuit recovery algorithm is proposed to perform the CSIT recovery, with the capability of exploiting the hidden joint sparsity in the user channel matrices. We analyze the obtained CSIT quality in terms of the normalized mean absolute error, and through the closed-form expressions, we obtain simple insights into how the joint channel sparsity can be exploited to improve the CSIT recovery performance.
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.
Capacity Optimized CDMA-MIMO Antenna System for Spectral-Efficient Wireless Networks
Directory of Open Access Journals (Sweden)
Nirmalendu Bikas Sinha and Abhishek Mitra
2011-03-01
Full Text Available With the explosion of wireless data traffic there is an increasing emphasis on techniques that can enhance the spectral efficiency and utilization of scarce wireless bandwidth. The future generation (4G Wireless Networks aim at offering very high data rates and flexibility by supporting multiple users by adopting multicarrier (MC transmissions. Multi-Input Multi-Output (MIMO has emerged as a hot topic in wireless communications during the last decade. This is due to possible dramatic increase in reliability and capacity as compared to single-antenna solutions. In this study, an attempt has been made to increase the capacity of a CDMA-based MIMO system by exploiting the frequency selectivity of the channel. The proposed system turns a MIMO frequency selective channel to a set of parallel multiplexing sub-channels in space and time domain. Numerical results show that the proposed CDMA MIMO antenna systems further increase the number of subchannels by exploiting the frequency selectivity of the channel, which leads to a significant increase in both the average capacity and the outage capacity.
Srinivasa, Narayan; Zhang, Deying; Grigorian, Beayna
2014-03-01
This paper describes a novel architecture for enabling robust and efficient neuromorphic communication. The architecture combines two concepts: 1) synaptic time multiplexing (STM) that trades space for speed of processing to create an intragroup communication approach that is firing rate independent and offers more flexibility in connectivity than cross-bar architectures and 2) a wired multiple input multiple output (MIMO) communication with orthogonal frequency division multiplexing (OFDM) techniques to enable a robust and efficient intergroup communication for neuromorphic systems. The MIMO-OFDM concept for the proposed architecture was analyzed by simulating large-scale spiking neural network architecture. Analysis shows that the neuromorphic system with MIMO-OFDM exhibits robust and efficient communication while operating in real time with a high bit rate. Through combining STM with MIMO-OFDM techniques, the resulting system offers a flexible and scalable connectivity as well as a power and area efficient solution for the implementation of very large-scale spiking neural architectures in hardware.
Polynomial expansion of the precoder for power minimization in large-scale MIMO systems
Sifaou, Houssem
2016-07-26
This work focuses on the downlink of a single-cell large-scale MIMO system in which the base station equipped with M antennas serves K single-antenna users. In particular, we are interested in reducing the implementation complexity of the optimal linear precoder (OLP) that minimizes the total power consumption while ensuring target user rates. As most precoding schemes, a major difficulty towards the implementation of OLP is that it requires fast inversions of large matrices at every new channel realizations. To overcome this issue, we aim at designing a linear precoding scheme providing the same performance of OLP but with lower complexity. This is achieved by applying the truncated polynomial expansion (TPE) concept on a per-user basis. To get a further leap in complexity reduction and allow for closed-form expressions of the per-user weighting coefficients, we resort to the asymptotic regime in which M and K grow large with a bounded ratio. Numerical results are used to show that the proposed TPE precoding scheme achieves the same performance of OLP with a significantly lower implementation complexity. © 2016 IEEE.
DEFF Research Database (Denmark)
Nguyen, Hung Tuan; Kovacs, Istvan
2012-01-01
In this paper we study the performance enhancement of a downlink LTE-Advanced system with a combination of the multi-user MIMO and carrier aggregation transmission techniques. Radio resource management for the systems with the combined features are proposed, and the system performance is evaluate...... that MU-MIMO transmission technique can help to enhance the cell-edge performance of the CA system by 10%-40% depending on traffic load....
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.
Ishihara, Koichi; Asai, Yusuke; Kudo, Riichi; Ichikawa, Takeo; Takatori, Yasushi; Mizoguchi, Masato
2013-12-01
Multiuser multiple-input multiple-output (MU-MIMO) has been proposed as a means to improve spectrum efficiency for various future wireless communication systems. This paper reports indoor experimental results obtained for a newly developed and implemented downlink (DL) MU-MIMO orthogonal frequency division multiplexing (OFDM) transceiver for gigabit wireless local area network systems in the microwave band. In the transceiver, the channel state information (CSI) is estimated at each user and fed back to an access point (AP) on a real-time basis. At the AP, the estimated CSI is used to calculate the transmit beamforming weight for DL MU-MIMO transmission. This paper also proposes a recursive inverse matrix computation scheme for computing the transmit weight in real time. Experiments with the developed transceiver demonstrate its feasibility in a number of indoor scenarios. The experimental results clarify that DL MU-MIMO-OFDM transmission can achieve a 972-Mbit/s transmission data rate with simple digital signal processing of single-antenna users in an indoor environment.
Multiuser Detection in MIMO-OFDM Wireless Communication System Using Hybrid Firefly Algorithm
Directory of Open Access Journals (Sweden)
B. Sathish Kumar
2014-05-01
Full Text Available In recent years, future generation wireless communication technologies are most the prominent fields in which many innovative techniques are used for effective communication. Orthogonal frequency-division multiplexing is one of the important technologies used for communication in future generation technologies. Although it gives efficient results, it has some problems during the implementation in real-time. MIMO and OFDM are integrated to have both their benefits. But, noise and interference are the major issues in the MIMO OFDM systems. To overcome these issues multiuser detection method is used in MIMO OFDM. Several algorithms and mathematical formulations have been presented for solving multiuser detection problem in MIMO OFDM systems. The algorithms such as genetic simulated annealing algorithm, hybrid ant colony optimization algorithm are used for multiuser detection problem in previous studies. But, due to the limitations of those optimization algorithms, the results obtained are not significant. In this research, to overcome the noise and interference problems, hybrid firefly optimization algorithm based on the evolutionary algorithm is proposed. The proposed algorithm is compared with the existing multiuser detection algorithm such as particle swarm optimization, CEFM-GADA [complementary error function mutation (CEFM and a differential algorithm (DA genetic algorithm (GA] and Hybrid firefly optimization algorithm based on evolutionary algorithm. The simulation results shows that performance of the proposed algorithm is better than the existing algorithm and it provides a satisfactory trade-off between computational complexity and detection performance
Non linear system become linear system
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Petre Bucur
2007-01-01
Full Text Available The present paper refers to the theory and the practice of the systems regarding non-linear systems and their applications. We aimed the integration of these systems to elaborate their response as well as to highlight some outstanding features.
He, Jiale; Li, Borui; Deng, Lei; Tang, Ming; Gan, Lin; Fu, Songnian; Shum, Perry Ping; Liu, Deming
2016-06-13
In this paper, the feasibility of space division multiplexing for optical wireless fronthaul systems is experimentally demonstrated by implementing high speed MIMO-OFDM/OQAM radio signals over 20km 7-core fiber and 0.4m wireless link. Moreover, the impact of optical inter-core crosstalk in multicore fibers on the proposed MIMO-OFDM/OQAM radio over fiber system is experimentally evaluated in both SISO and MIMO configurations for comparison. The experimental results show that the inter-core crosstalk tolerance of the proposed radio over fiber system can be relaxed to -10 dB by using the proposed MIMO-OFDM/OQAM processing. These results could guide high density multicore fiber design to support a large number of antenna modules and a higher density of radio-access points for potential applications in 5G cellular system.
Adaptive antenna selection and Tx/Rx beamforming for large-scale MIMO systems in 60 GHz channels
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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.
Simplified transmitter design for MIMO systems with channel uncertainty
Institute of Scientific and Technical Information of China (English)
DU Juan; KANG Gui-xia; ZHANG Ping
2009-01-01
This article investigates transmitter design in Rayleigh fading multiple input multiple output (MIMO) channels with spatial correlation when there are channel uncertainties caused by a combined effect of channel estimation error and limited feedback. To overcome the high computational complexity of the optimal transmit power allocation, a simple and suboptimal allocation is proposed by exploiting the transmission constraint and differentiating a bound based on Jensen inequality on the channel capacity. The simulation results show that the mutual information corresponding to the proposed power allocation closely approaches the channel capacity corresponding to the optimal one and meanwhile the computational complexity is greatly reduced.
Finite time control for MIMO nonlinear system based on higher-order sliding mode.
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.
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Wen OliverYu
2011-01-01
Full Text Available For multiple-input multiple-output (MIMO wireless communication system with minimum mean square error (MMSE detection, a new scheme of power allocation between pilot and data symbols is investigated under MMSE channel estimation in this paper. First, we propose a novel soft-output MMSE MIMO detector by taking into consideration the channel estimation error. Then, through the application of random matrix theorem, we propose an efficient scheme for power allocation between pilot and data symbols which maximizes the lower bound of postprocessing signal-to-interference-and-noise ratio (SINR for MIMO systems with equal number of transmitter and receiver antennas. We have proven the existence and uniqueness of the proposed optimal power allocation settings. Furthermore, our analysis shows that the proposed power allocation is also valid and applicable for those MIMO systems with unequal number of transmitter and receiver antennas. Finally, our extensive simulation results have validated this novel power allocation scheme.
Adaptive Fuzzy Tracking Control for a Class of MIMO Nonlinear Systems in Nonstrict-Feedback Form.
Chen, Bing; Lin, Chong; Liu, Xiaoping; Liu, Kefu
2015-12-01
This paper focuses on the problem of fuzzy adaptive control for a class of multiinput and multioutput (MIMO) nonlinear systems in nonstrict-feedback form, which contains the strict-feedback form as a special case. By the condition of variable partition, a new fuzzy adaptive backstepping is proposed for such a class of nonlinear MIMO systems. The suggested fuzzy adaptive controller guarantees that the proposed control scheme can guarantee that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded and the tracking errors eventually converge to a small neighborhood around the origin. The main advantage of this paper is that a control approach is systematically derived for nonlinear systems with strong interconnected terms which are the functions of all states of the whole system. Simulation results further illustrate the effectiveness of the suggested approach.
Adaptive rational block Arnoldi methods for model reductions in large-scale MIMO dynamical systems
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Khalide Jbilou
2016-04-01
Full Text Available In recent years, a great interest has been shown towards Krylov subspace techniques applied to model order reduction of large-scale dynamical systems. A special interest has been devoted to single-input single-output (SISO systems by using moment matching techniques based on Arnoldi or Lanczos algorithms. In this paper, we consider multiple-input multiple-output (MIMO dynamical systems and introduce the rational block Arnoldi process to design low order dynamical systems that are close in some sense to the original MIMO dynamical system. Rational Krylov subspace methods are based on the choice of suitable shifts that are selected a priori or adaptively. In this paper, we propose an adaptive selection of those shifts and show the efficiency of this approach in our numerical tests. We also give some new block Arnoldi-like relations that are used to propose an upper bound for the norm of the error on the transfer function.
基于空时Turbo网格码的MIMO-OFDM系统%MIMO-OFDM System With Space-time Turbo Trellis Code
Institute of Scientific and Technical Information of China (English)
张倩; 贠莹; 袁小刚
2012-01-01
An MIMO-OFDM system with space-time turbo trellis code is proposed in this paper. The performance of the system in fading channel is analyzed Through the simulation, it proves that this system with space-time Turbo trellis code can acquire better gain of diversity and code.%提出了使用空时Turbo网格编码的MIMO-OFDM系统,分析了系统的性能,给出了衰落信道中的性能上界以及编码和分集增益表达式.通过仿真评估了空时Turbo网格码在慢衰落信道中的性能,与传统的STTC方法相比,该系统可以获得更好的分集增益和编码增益.
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K. Rajeswari
2015-04-01
Full Text Available A novel hybrid channel estimator is proposed for multiple-input multiple-output orthogonal frequency- division multiplexing (MIMO-OFDM system with per-subcarrier transmit antenna selection having optimal power allocation among subcarriers. In practice, antenna selection information is transmitted through a binary symmetric control channel with a crossover probability. Linear minimum mean-square error (LMMSE technique is optimal technique for channel estimation in MIMO-OFDM system. Though LMMSE estimator performs well at low signal to noise ratio (SNR, in the presence of antenna-to-subcarrier-assignment error (ATSA, it introduces irreducible error at high SNR. We have proved that relaxed MMSE (RMMSE estimator overcomes the performance degradation at high SNR. The proposed hybrid estimator combines the benefits of LMMSE at low SNR and RMMSE estimator at high SNR. The vector mean square error (MSE expression is modified as scalar expression so that an optimal power allocation can be performed. The convex optimization problem is formulated and solved to allocate optimal power to subcarriers minimizing the MSE, subject to transmit sum power constraint. Further, an analytical expression for SNR threshold at which the hybrid estimator is to be switched from LMMSE to RMMSE is derived. The simulation results show that the proposed hybrid estimator gives robust performance, irrespective of ATSA error.
Institute of Scientific and Technical Information of China (English)
李全忠; 黄济宇; 罗丽平; 秦家银
2012-01-01
This paper considers linear transceiver design for amplify-and-forward multiple-input multiple-output (MMO) multiple-relay systems,aiming to minimize the mean squared error (MSE) under the total relay transmit power constraint.We first introduce the singular value decomposition (SVD) of matrix product and simplify the original optimization problem to one which takes a singular value vector and a unitary matrix as optimization variables.By employing variable substitution and penalty term, the simplified problem only has one unitary matrix constraint.Then we develop a new Riemann Euclidean steepest descent algorithm to deal with the unitary matrix constraint.Finally,simulation results demonstrate that the performance of the proposed scheme is better than traditional schemes and closes to the lower bound of MSE.%本文以放大转发MIMO多中继系统为研究对象,研究其联合线性收发机的优化设计问题,其基本思想是在中继的总发射功率约束下,最小化系统的均方误差(MSE).为降低系统复杂度,本文首先引入了乘积矩阵的奇异值分解,把收发机的设计简化为以奇异值向量和酉矩阵为优化变量的优化问题;接着利用变量替换并引入罚项,将简化后的问题转化成只有酉矩阵约束的优化问题.在此基础上,通过引入替换变量的欧氏梯度,设计了新的黎曼欧氏最陡下降算法,从而有效地处理酉矩阵约束.仿真结果表明,与传统的设计方法相比,本文提出的方案性能最优,最接近MSE下界.
On the mutual information of 3D massive MIMO systems: An asymptotic approach
Nadeem, Qurrat-Ul-Ain
2015-10-01
Motivated by the recent interest in 3D beamforming to enhance system performance, we present an information-theoretic channel model for multiple-input multiple-output (MIMO) systems, that can support the elevation dimension. The principle of maximum entropy is used to determine the distribution of the channel matrix consistent with the prior angular information. We provide an explicit expression for the cumulative density function (CDF) of the mutual information in the large number of transmit antennas and paths regime. The derived Gaussian approximation is quite accurate even for realistic system dimensions. The simulation results study the achievable performance through the meticulous selection of the transmit antenna downtilt angles. The results are directly applicable to the analysis of 5G 3D massive MIMO systems. © 2015 IEEE.
Achievable Rates of UAV-Relayed Cooperative Cognitive Radio MIMO Systems
Sboui, Lokman
2017-04-19
We study the achievable rate of an uplink MIMO cognitive radio system where the primary user (PU) and the secondary user (SU) aim to communicate to the closest primary base station (BS) via a multi-access channel through the same unmanned aerial vehicle (UAV) relay. The SU message is then forwarded from the primary BS to the secondary network with a certain incentive reward as a part of the cooperation protocol between both networks. A special linear precoding scheme is proposed to enable the SU to exploit the PU free eigenmodes. We analyze two scenarios in which the UAV relay gain matrix is either fixed or optimized. We derive the optimal power allocation that maximizes the achievable rate of the SU respecting power budget, interference, and relay power constraints. Numerical results highlight the cognitive rate gain of our proposed scheme with respect to various problem parameters. We also highlight the effect of UAV altitude on the SU and PU rates. Finally, when the relay matrix is optimized, we show that the PU rate is remarkably enhanced and that the SU rate is only improved at high power regime.
On performance analysis of ADRC for a class of MIMO lower-triangular nonlinear uncertain systems.
Xue, Wenchao; Huang, Yi
2014-07-01
This paper designs the active disturbance rejection control (ADRC) to achieve desired performance for a class of MIMO lower-triangular nonlinear systems with large uncertainties under un-matched condition. We develop the ADRC with a set of extended state observers, and prove that the closed-loop system can achieve satisfied dynamic performance. The theoretical results illustrate the relationship between the bound of the concerned error and the bandwidth of extend state observers.
Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System.
Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi
2015-01-01
The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system.
Multivariable design of improved linear quadratic regulation control for MIMO industrial processes.
Zhang, Ridong; Lu, Renquan; Jin, Qibing
2015-07-01
In this study, a multivariable linear quadratic control system using a new state space structure was developed for the chamber pressure in the industrial coke furnace. Such processes typically have complex and nonlinear dynamic behavior, which causes the performance of controllers using conventional design and tuning to be poor or to require significant effort in practice. The process model is first treated into a new state space form and the implementation of linear quadratic control is designed using this new model structure. Performance in terms of regulatory/servo, disturbance rejection and measurement noise problems were all compared with the recent model predictive control strategy. Results revealed that the control system showed more robustness and improved the closed-loop process performance under model/process mismatches.
A Practical, Hardware Friendly MMSE Detector for MIMO-OFDM-Based Systems
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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 4ÃƒÂ—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 420Ã¢Â€Â‰Mbps sustained throughput with a small 2.77-microsecond latency. The designed 4ÃƒÂ—4 linear MMSE MIMO detector is capable of complying with the proposed IEEE 802.11n standard.
Video Transmission over MIMO-OFDM System: MDC and Space-Time Coding-Based Approaches
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Haifeng Zheng
2007-03-01
Full Text Available MIMO-OFDM is a promising technique for the broadband wireless communication system. In this paper, we propose a novel scheme that integrates multiple-description coding (MDC, error-resilient video coding, and unequal error protection strategy with hybrid space-time coding structure for robust video transmission over MIMO-OFDM system. The proposed MDC coder generates multiple bitstreams of equal importance which are very suitable for multiple-antennas system. Furthermore, according to the contribution to the reconstructed video quality, we apply unequal error protection strategy using BLAST and STBC space-time codes for each video bitstream. Experimental results have demonstrated that the proposed scheme can be an excellent alternative to achieve desired tradeoff between the reconstructed video quality and the transmission efficiency.
Optimal power allocation for homogeneous and heterogeneous CA-MIMO systems
Institute of Scientific and Technical Information of China (English)
CUI QiMei; KANG PeiChuan; HUANG XueQing; VALKAMA Mikko; NIEMELA Jarno
2013-01-01
Carrier aggregation （CA） technique has been adopted by 3GPP LTE-Advanced due to its ability of enhancing the spectrum efficiency and peak data rates through aggregating multiple component carriers （CCs）. Two main factors make power control optimization very essential for CA-MIMO radio link： the different channel characteristics in multiple CCs, and multiple power constraint conditions （per-CC, per-antenna and pertransmitter power constraints） in the actual CA system deployment. This paper firstly derives the degenerate conditions of optimal power allocation for a single-transmitter CA-MIMO system. Stemming from the derived degenerate conditions, we propose a modified hybrid gradient optimal power allocation（MHGOPA） algorithm to maximize the system performance. Simulation results verify the validity of the proposed resource allocation approach by comparing with baseline average power allocation algorithm. Finally, we extend the MHGOPA algorithm into a heterogeneous CA network with multiple transmitters working simultaneously.
Antenna selection based on large-scale fading for distributed MIMO systems
Institute of Scientific and Technical Information of China (English)
施荣华
2016-01-01
An antenna selection algorithm based on large-scale fading between the transmitter and receiver is proposed for the uplink receive antenna selection in distributed multiple-input multiple-output ( D-MIMO) systems.By utilizing the radio access units ( RAU) selection based on large-scale fa-ding , the proposed algorithm decreases enormously the computational complexity .Based on the characteristics of distributed systems , an improved particle swarm optimization ( PSO) has been pro-posed for the antenna selection after the RAU selection .In order to apply the improved PSO algo-rithm better in antenna selection , a general form of channel capacity was transformed into a binary expression by analyzing the formula of channel capacity .The proposed algorithm can make full use of the advantages of D-MIMO systems , and achieve near-optimal performance in terms of channel ca-pacity with low computational complexity .
Hu, Chia-Chang; Su, Hao-Hsian; Tang, Kang-Tsao
2014-09-01
This paper considers a two-way multiple-input multiple-output (MIMO) relaying system with multiple relays between two terminals nodes. The relay antenna selection scheme based on channel singular valued decomposition (SVD) is used to reduce energy consumption. To enhance the system performance, we apply a SVD-based algorithm with MSE criterion which calculates optimal linear transceivers precoding jointly at the source nodes and relay nodes for amplify-and-forward (AF) protocols. In computer simulations, we use an iteration method to compute the non-convex function of joint source and relays power allocation. The simulation results show the SVD-based precoding design with SVD-based relay and antenna selection scheme can achieve a superior system bit error rate (BER) performance and reduce the power consume of relay antennas.
Modeling and control of non-square MIMO system using relay feedback.
Kalpana, D; Thyagarajan, T; Gokulraj, N
2015-11-01
This paper proposes a systematic approach for the modeling and control of non-square MIMO systems in time domain using relay feedback. Conventionally, modeling, selection of the control configuration and controller design of non-square MIMO systems are performed using input/output information of direct loop, while the output of undesired responses that bears valuable information on interaction among the loops are not considered. However, in this paper, the undesired response obtained from relay feedback test is also taken into consideration to extract the information about the interaction between the loops. The studies are performed on an Air Path Scheme of Turbocharged Diesel Engine (APSTDE) model, which is a typical non-square MIMO system, with input and output variables being 3 and 2 respectively. From the relay test response, the generalized analytical expressions are derived and these analytical expressions are used to estimate unknown system parameters and also to evaluate interaction measures. The interaction is analyzed by using Block Relative Gain (BRG) method. The model thus identified is later used to design appropriate controller to carry out closed loop studies. Closed loop simulation studies were performed for both servo and regulatory operations. Integral of Squared Error (ISE) performance criterion is employed to quantitatively evaluate performance of the proposed scheme. The usefulness of the proposed method is demonstrated on a lab-scale Two-Tank Cylindrical Interacting System (TTCIS), which is configured as a non-square system.
Design of Joint Spatial and Power Domain Multiplexing Scheme for Massive MIMO Systems
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Zheng Jiang
2015-01-01
Full Text Available Massive Multiple-Input Multiple-Output (MIMO is one of the key techniques in 5th generation wireless systems (5G due to its potential ability to improve spectral efficiency. Most of the existing works on massive MIMO only consider Time Division Duplex (TDD operation that relies on channel reciprocity between uplink and downlink channels. For Frequency Division Duplex (FDD systems, with continued efforts, some downlink multiuser MIMO scheme was recently proposed in order to enable “massive MIMO” gains and simplified system operations with limited number of radio frequency (RF chains in FDD system. However these schemes, such as Joint Spatial Division and Multiplexing (JSDM scheme and hybrid precoding scheme, only focus on multiuser transmission in spatial domain. Different from most of the existing works, this paper proposes Joint Spatial and Power Multiplexing (JSPM scheme in FDD systems. It extends existing FDD schemes from spatial division and multiplexing to joint spatial and power domain to achieve more multiplexing gain. The user grouping and scheduling scheme of JSPM is studied and the asymptotic expression for the sum capacity is derived as well. Finally, simulations are conducted to illustrate the effectiveness of the proposed scheme.
Performance analysis of MIMO FSO systems with radial array beams and finite sized detectors
Gökçe, Muhsin C.; Kamacıoǧlu, Canan; Uysal, Murat; Baykal, Yahya
2014-10-01
Multiple-input multiple-output (MIMO) systems are employed in free space optical (FSO) links to mitigate the degrading effects of atmospheric turbulence. In this paper, we consider a MIMO FSO system with practical transmitter and receiver configurations that consists of a radial laser array with Gaussian beams and finite sized detectors. We formulate the average received intensity and the power scinitillation as a function of the receiver coordinates in the presence of weak atmospheric turbulence by using the extended Huygens-Fresnel principle. Then, integrations over the finite sized multiple detectors are performed and the effect of the receiver aperture averaging is quantified. We further derive an outage probability expression of this MIMO system in the presence of turbulence-induced fading channels. Using the derived expressions, we demonstrate the effect of several practical system parameters such as the ring radius, the number of array beamlets, the source size, the link length, structure constant and the receiver aperture radius on the system performance.
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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.
Impact of Mobility on MIMO Green Wireless Systems
Varma, Vineeth S; Lasaulce, Samson; Elayoubi, Salah Eddine
2011-01-01
This paper studies the impact of mobility on the power consumption of wireless networks. With increasing mobility, we show that the network should dedicate a non negligible fraction of the useful rate to estimate the different degrees of freedom. In order to keep the rate constant, we quantify the increase of power required for several cases of interest. In the case of a point to point MIMO link, we calculate the minimum transmit power required for a target rate and outage probability as a function of the coherence time and the number of antennas. Interestingly, the results show that there is an optimal number of antennas to be used for a given coherence time and power consumption. This provides a lower bound limit on the minimum power required for maintaining a green network.
Performance Analysis of STTC MIMO-OFDM Systems over Rayleigh Fading Channels
Institute of Scientific and Technical Information of China (English)
BAIWei; HEChen; JIANGLingge
2003-01-01
Multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) is one of the most promising scheme for achieving high data rate and large system capacity over wireless networks. This paper addresses the error performance analysis of the Space-time trellis code (STTC) MIMO-OFDM systems over quasistatic, frequency selective Rayleigh fading channels. Using the Chernoff bound combined with transfer function bounding technique, we provide a new analytical method. To quantify the upper bound of the error performance, we derive the probability density function (pdf) of the frequency domain fading channel and make a novel approximation to the Euclidean distance. Monte Carlo simulation results indicate that the derived upper bounds are quite accurate in a broad range of Signal-to-noise ratio (SNR).
In vivo measurement of human knee and hip dynamics using MIMO system identification.
Koopman, B; van Asseldonk, E F; van der Kooij, H
2010-01-01
This study presents a new method for the estimation of the dynamic impedance of multi-joint leg movements. The method is based on Multi Input Multi Output (MIMO) system identification techniques and is designed for continuous torque perturbations at the hip and knee joint. Preliminary results from this study indicate that MIMO system identification can successfully be used to estimate the hip and knee impedance and the interaction dynamics between both joints. It is also concluded that, in order to create a good model representation of the leg impedance, the effect of biarticular muscles needs to be taken into account. The obtained measures for joint impedance might be used for clinical assessment and follow up of patients, as well as for the development of supportive devices.
Ermolayev, V. T.; Flaksman, A. G.; Averin, I. M.; Gribov, D. V.
2004-02-01
We consider multiple-input multiple-output (MIMO) cellular communication systems with antenna arrays at both link ends and data transmission via parallel eigenchannels matched with a random spatial channel. We analyze the effectiveness of the space-division multiple-access (SDMA) method, which does not require estimation of signal-arrival directions and is based on orthogonalization of the parallel channels of all users. We obtained approximate analytical expressions for the mean ratio of the signal power to the noise power and the MIMO system capacity, which are derived for the case of Rayleigh fading of signals. Although the obtained formulas are much simpler than the exact ones, they ensure high accuracy for an arbitrary number of transmitting and receiving antennas and an arbitrary power of transmitter. Our results demonstrate the high effectiveness of the proposed SDMA method.
Opportunistic Scheduling and Beamforming for MIMO-OFDMA Downlink Systems with Reduced Feedback
Pun, Man-On; Poor, H Vincent
2008-01-01
Opportunistic scheduling and beamforming schemes with reduced feedback are proposed for MIMO-OFDMA downlink systems. Unlike the conventional beamforming schemes in which beamforming is implemented solely by the base station (BS) in a per-subcarrier fashion, the proposed schemes take advantages of a novel channel decomposition technique to perform beamforming jointly by the BS and the mobile terminal (MT). The resulting beamforming schemes allow the BS to employ only {\\em one} beamforming matrix (BFM) to form beams for {\\em all} subcarriers while each MT completes the beamforming task for each subcarrier locally. Consequently, for a MIMO-OFDMA system with $Q$ subcarriers, the proposed opportunistic scheduling and beamforming schemes require only one BFM index and $Q$ supportable throughputs to be returned from each MT to the BS, in contrast to $Q$ BFM indices and $Q$ supportable throughputs required by the conventional schemes. The advantage of the proposed schemes becomes more evident when a further feedback ...
Game Theoretical Power Control for Open-Loop Overlaid Network MIMO Systems with Partial Cooperation
Yu, Hao; Lau, Vincent K N
2010-01-01
Network MIMO is considered to be a key solution for the next generation wireless systems in breaking the interference bottleneck in cellular systems. In the MIMO systems, open-loop transmission scheme is used to support mobile stations (MSs) with high mobilities because the base stations (BSs) do not need to track the fast varying channel fading. In this paper, we consider an open-loop network MIMO system with $K$ BSs serving K private MSs and $M^c$ common MS based on a novel partial cooperation overlaying scheme. Exploiting the heterogeneous path gains between the private MSs and the common MSs, each of the $K$ BSs serves a private MS non-cooperatively and the $K$ BSs also serve the $M^c$ common MSs cooperatively. The proposed scheme does not require closed loop instantaneous channel state information feedback, which is highly desirable for high mobility users. Furthermore, we formulate the long-term distributive power allocation problem between the private MSs and the common MSs at each of the $K$ BSs using...
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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.
Near-Optimal Hybrid Processing for Massive MIMO Systems via Matrix Decomposition
Ni, Weiheng; Dong, Xiaodai; Lu, Wu-Sheng
2015-01-01
For the practical implementation of massive multiple-input multiple-output (MIMO) systems, the hybrid processing (precoding/combining) structure is promising to reduce the high cost rendered by large number of RF chains of the traditional processing structure. The hybrid processing is performed through low-dimensional digital baseband processing combined with analog RF processing enabled by phase shifters. We propose to design hybrid RF and baseband precoders/combiners for multi-stream transm...
Phase-Shift Cyclic-Delay Diversity for MIMO OFDM Systems
Directory of Open Access Journals (Sweden)
Young-Han Nam
2010-01-01
Full Text Available Phase-shift cyclic-delay diversity (PS CDD scheme and space-frequency-block-code (SFBC PS CDD are developed for multiple-input-multiple-output (MIMO orthogonal frequency division multiplexing (OFDM systems. The proposed PS CDD scheme preserves the diversity advantage of traditional CDD in uncorrelated multiantenna channels, and furthermore removes frequency-selective nulling problem of the traditional CDD in correlated multiantenna channels.
Directory of Open Access Journals (Sweden)
Ivaniš Predrag
2004-01-01
Full Text Available This paper presents combination of Channel Optimized Vector Quantization based on LBG algorithm and sub channel power allocation for MIMO systems with Singular Value Decomposition and limited number of active sub channels. Proposed algorithm is designed to enable maximal throughput with bit error rate bellow some tar- get level in case of backward channel capacity limitation. Presence of errors effect in backward channel is also considered.
A MU-MIMO CQI estimation method for MU-MIMO UEs in LTE systems
DEFF Research Database (Denmark)
Nguyen, Hung Tuan; Kovacs, Istvan
2012-01-01
Abstract—This paper addresses a method to estimate the multi user channel quality indicator (CQI) from the reported rank 1 single user CQI in LTE systems. We investigate the relationship between the multi user CQI and the channel condition. Based on that, we propose an updating mechanism where...
Institute of Scientific and Technical Information of China (English)
Tian-Ping Zhang; Cai-Ying Zhou; Qing Zhu
2009-01-01
In this paper, adaptive variable structure neural control is presented for a class of uncertain multi-input multi-output (MIMO) nonlinear systems with state time-varying delays and unknown nonlincar dead-zones. The unknown time-varying delay uncertainties are compensated for using appropriate Lyapunov-Krasovskii functionals in the design. The approach removes the assumption of linear function outside the deadband without necessarily constructing a dead-zone inverse as an added contribution. By utilizing the integral-type Lyapunov function and introducing an adaptive compensation term for the uppcr bound of the residual and optimal approximation error as well as the dead-zone disturbance, the closed-loop control system is proved to be semi-globally uniformly ultimately bounded. In addition, a modified adaptive control algorithm is given in order to avoid the high-frequency chattering phenomenon. Simulation results demonstrate the effectiveness of the approach.
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.
On the MIMO Capacity for Distributed System under Composite Rayleigh/Rician Fading and Shadowing
Directory of Open Access Journals (Sweden)
Santiago González-Aurioles
2015-01-01
Full Text Available Wireless channels are commonly affected by short-term fading and long-term fading (shadowing. The shadowing effects must be taken into account also when mobility is present in the wireless scenario. Using a composite fading model, the total channel capacity can be studied for a scenario with short-term Rayleigh fading along with shadowing. This work provides quantitative results for these kinds of scenarios with Rayleigh fading and shadowing, considering also multiple-input and multiple-output systems, which have not been previously reported. In addition, the channel capacity has been studied in depth in its relation with the shadowing level, signal to noise ratio, and the number of elements in the multiple-input and multiple-output system. Moreover, the channel performance with shadowing has been compared to the one without it. Furthermore, Rician model with shadowing is studied and its results are reported. In addition, correlated and experimental results are provided. It is identified that the distributed MIMO systems can benefit from shadowing in Rician channels. This advantage has not been reported previously. This type of fading is proposed for massive MIMO by others and our results open the door to emulate massive MIMO on a reverberation chamber.
An Improved Multicell MMSE Channel Estimation in a Massive MIMO System
Directory of Open Access Journals (Sweden)
Ke Li
2014-01-01
Full Text Available Massive MIMO is a promising technology to improve both the spectrum efficiency and the energy efficiency. The key problem that impacts the throughput of a massive MIMO system is the pilot contamination due to the nonorthogonality of the pilot sequences in different cells. Conventional channel estimation schemes cannot mitigate this problem effectively, and the computational complexity is increasingly becoming larger in views of the large number of antennas employed in a massive MIMO system. Furthermore, the channel estimation is always carried out with some ideal assumptions such as the complete knowledge of large-scale fading. In this paper, a new channel estimation scheme is proposed by utilizing interference cancellation and joint processing. Highly interfering users in neighboring cells are identified based on the estimation of large-scale fading and then included in the joint channel processing; this achieves a compromise between the effectiveness and efficiency of the channel estimation at a reasonable computational cost, and leads to an improvement in the overall system performance. Simulation results are provided to demonstrate the effectiveness of the proposed scheme.
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.
Distributed Channel Estimation and Pilot Contamination Analysis for Massive MIMO-OFDM Systems
Zaib, Alam
2016-07-22
By virtue of large antenna arrays, massive MIMO systems have a potential to yield higher spectral and energy efficiency in comparison with the conventional MIMO systems. This paper addresses uplink channel estimation in massive MIMO-OFDM systems with frequency selective channels. We propose an efficient distributed minimum mean square error (MMSE) algorithm that can achieve near optimal channel estimates at low complexity by exploiting the strong spatial correlation among antenna array elements. The proposed method involves solving a reduced dimensional MMSE problem at each antenna followed by a repetitive sharing of information through collaboration among neighboring array elements. To further enhance the channel estimates and/or reduce the number of reserved pilot tones, we propose a data-aided estimation technique that relies on finding a set of most reliable data carriers. Furthermore, we use stochastic geometry to quantify the pilot contamination, and in turn use this information to analyze the effect of pilot contamination on channel MSE. The simulation results validate our analysis and show near optimal performance of the proposed estimation algorithms.
Leakage based precoding for multi-user MIMO-OFDM systems
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.
Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System
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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.
Gutman, Igor; Wulich, Dov
2009-01-01
Multiple input multiple output (MIMO) precoding is an efficient scheme that may significantly enhance the communication link. However, this enhancement comes with a cost. Many precoding schemes require channel knowledge at the transmitter that is obtained through feedback from the receiver. Focusing on the natural common fusion of orthogonal frequency division multiplexing (OFDM) and MIMO, we exploit the channel correlation in the frequency and spatial domain to reduce the required feedback rate in a frequency division duplex (FDD) system. The proposed feedback method is based on Huffman coding and is employed here for the single stream case. The method leads to a significant reduction in the required feedback rate, without any loss in performance. The proposed method may be extended to the multi-stream case.
Bai, Lin
2012-01-01
Methods of signal detection are becoming an ever more vital component of wireless services, as providers lean towards using multiple antennae to compensate for limitations in the available wireless spectrum. The co-authors of this book are two of the world’s leading authorities on so-called MIMO (multiple-input, multiple-output) systems, and here they share the key findings of their years of research. They detail a range of important techniques for signal detection when multiple transmitted and received signals are available. They then review and explain some conventional MIMO detection schemes, including the ML, linear, and SIC detectors, and show why these methodologies are less than optimal compared to the more versatile list decoding and lattice reduction-aided detection systems. In the second part of the book, the authors move on to discuss various user selection schemes in multiuser systems. Its finely tuned balance of theoretical analysis and practical applications makes this book required reading...
Research on reverse identification range of MIMO-RFID systems%MIMO-RFID系统反向识别距离研究
Institute of Scientific and Technical Information of China (English)
佘开; 何怡刚; 朱彦卿; 方葛丰
2012-01-01
超高频(UHF)射频识别系统(RFID)读取可靠性受多径信道制约,而多天线分集技术(MIMO)被认为能有效提高其链路可靠性.不同于一般的无线通信系统,UHF RFID反向链路是两个多径信道的级联,本文基于最大比合并(MRC)准则,分阅读器单站和双站天线情形,导出了Nakagami-m多径信道下单天线(SISO)与多天线(MIMO)RFID系统反向识别距离(RIR)均值的解析表达式,并通过数值仿真和实际测试研究了相关因素对RIR均值的影响.实验结果表明:MIMO技术能有效提高多径信道下UHF RFID系统的反向识别距离,并且阵列天线数越多、信道相关系数越小、信道衰落参数m越大,RIR均值将越高.%The performance of UHF RFID system is constrained by multipath effects, and multi-antenna techniques (MIMO) can improve the reliability of propagation links. For the reverse links of MIM0-RF1D system, monostatic or bistatic, are both the cascade of two multipath channels. In the paper, the analytical expressions of average reverse identi-fication range (RIR) of single-antenna (SISO) and MIMO-RFID systems with maximal ratio combing (MRC) were de-rived. And several influencing factors of RIR were researched through numerical simulation and measurements. The ex-perimental results showed that MIMO technique can evidently increase the RIR of UHF RFID systems, and the more an-tennas, the lower the correlation coefficient of channels, and the larger fading parameters, the higher the RIR.
Optimization of an Angle-Aided Mirror Diversity Receiver for Indoor MIMO-VLC Systems
Park, Kihong
2017-02-07
In this paper, we investigate the channel correlation problem which affects the performance of indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems. More specifically, in order to reduce the high correlation of channel matrix in MIMO-VLC intensity channel, we propose a non-imaging receiver called angle-aided mirror diversity receiver (AMDR) which utilizes not only a mirror placement but also a variation of orientation angle for the photodetector (PD) plane. Deploying a mirror helps reducing the correlation by blocking the reception of the light in one specific direction and by receiving additional light reflected in the mirror in another direction, while orienting the angle of PD plane into specific direction enables the directional reception of light. Applying a zero-forcing decorrelator at the receiver, we analyze the bit error rate (BER) performance for a 2×2 multiplexing MIMO-VLC system using a 2-dimensional geometric model. In particular, we formulate a min-max BER problem and find the optimal height of mirror and elevation angle of PD plane. Some selected numerical results validate our proposed optimal solution to our min-max BER problem and show that the BER performance of our proposed AMDR outperforms that of the previous non-imaging receivers.
Energy Technology Data Exchange (ETDEWEB)
Reinschke, K. [Technische Univ. Dresden (Germany). Inst. fuer Regelungs- und Streuerungstheorie
2006-07-01
After the introduction of bachelor and master studies in Germany, new training concepts are required. In the field of engineering, there is a lack of research-oriented German-language textbooks which are also suited for further training of professionally experienced engineers. The author addresses readers with good prior knowledge of mathematics and application-oriented basic training in open-loop and control-loop engineering who intend to deepen their knowledge of the methods of control of linear time-continuous processes. The reader is enabled to apply the mathematical tools of linear system theory for control purposes. Unavoidable uncertainties in the modelling of control paths are considered. The focus is on function theoretical and algebraic aspects which enable the design of robust stabilising controllers as well as trajectory control and follow-up control and also the time-continuous treatment of scanning control loops. There are many examples to illustrate the general laws that are presented. (orig.) [German] Die Einfuehrung von gestuften Bachelor- und Master-Studiengaengen erfordert neue Ausbildungskonzepte. Fuer die Master- und Promotionsstudiengaenge der Ingenieure mangelt es bisher an forschungsorientierten deutschsprachigen Lehrwerken, die zugleich auch zur Fortbildung von berufserfahrenen Ingenieuren geeignet sind. Dieses Buch traegt zur Behebung dieses Mangels bei. Der Autor wendet sich an Leser, die eine gute mathematische Vorbildung und eine anwendungsorientierte Grundausbildung in Regelungs- und Steuerungstechnik abgeschlossen haben und nun tiefer in die Methoden der Regelung und Steuerung von linearen zeitkontinuierlichen Prozessen eindringen wollen. Der Leser wird befaehigt, die mathematischen Werkzeuge der linearen Systemtheorie fuer regelungstechnische Zwecke einzusetzen. Bei der Modellierung von Regelstrecken werden die unvermeidlichen Unbestimmtheiten beruecksichtigt. Im Zentrum stehen die funktionentheoretischen und algebraischen
Set-point Tracking in Mode-Observable Switching Linear Systems
Baglietto, Marco; Battistelli, Giorgio; Tesi, Pietro
2011-01-01
This paper addresses the problem of set-point tracking for a continuous-time process modeled by a multi-input multi-output (MIMO) linear system that may switch, in unknown and unpredictable fashion, among different modes taken from a finite set. The proposed methodology relies on an high level contr
大规模MIMO系统研究进展%Overview of Massive MIMO System
Institute of Scientific and Technical Information of China (English)
戚晨皓; 黄永明; 金石
2015-01-01
With the rapid development of wireless communications and the popularization of smartphones , higher data rate of the service is required .The demand can be efficiently and conveniently satisfied by in‐creasing the number of antennas at base station (BS) ,thus resulting in a massive MIMO system .The massive MIMO system can exploit the spatial degree of freedom ,and therefore BS is enabled to simulta‐neously serve several user equipments (UE) with the same temporal and frequency resource .Three key techniques are presented in the massive MIMO system ,including the pilot contamination issue and the corresponding solutions ,the theoretical and practical channel model that fits for the massive MIMO sys‐tem ,and the low complexity transmission and implement methods .Compared with the existing MIMO system ,the massive M IM O system can distinctively increase the spectral efficiency ,the energy efficien‐cy ,and the system robustness .As one of the most promising topics on the fifth generation (5G) of wire‐less communication systems ,the massive MIMO system has attracted the extensive attention worldwide . Nevertheless ,the research of massive MIMO systems is still at its early stage ,with a lot of technical problems to be solved .%随着无线通信技术的快速发展和智能手机的迅速普及，人们对数据传输速率提出了更高的需求。为进一步提高数据传输速率，通过增加基站天线数目构建大规模M IM O系统，是一种高效而相对便捷的方式。大规模M IM O系统能深度发掘空间维的自由度，使得基站能够利用同一时频资源服务于多个用户。本文探讨了大规模MIMO系统的导频污染问题及解决方案、适用于大规模MIMO系统的信道模型以及低复杂度的传输技术与实现方法三项关键技术。与现有MIMO系统相比，大规模MIMO系统能显著提高频谱效率、能量效率和系统的鲁棒性能。作为第五代移动通信（5G ）最具潜力
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.
Analysis of MIMO Systems used in planning a 4G-WiMAX Network in Ghana
Directory of Open Access Journals (Sweden)
E. T. Tchao
2013-08-01
Full Text Available with the increasing demand for mobile data services, Broadband Wireless Access (BWA is emerging as one of the fastest growing areas within mobile communications. Innovative wireless communication systems, such as WiMAX, are expected to offer highly reliable broadband radio access in order to meet the increasing demands of emerging high speed data and multimedia services. In Ghana, deployment of WiMAX technology has recently begun. Planning these high capacity networks in the presence of multiple interferences in order to achieve the aim of enabling users enjoy cheap and reliable internet services is a critical design issue. This paper has used a deterministic approach for simulating the Bit-Error-Rate (BER of initial MIMO antenna configurations which were considered in deploying a high capacity 4G-WiMAX network in Ghana. The radiation pattern of the antenna used in the deploying the network has been simulated with Genex-Unet and NEC and results presented. An adaptive 4x4 MIMO antenna configuration with optimally suppressed sidelobes has been suggested for future network deployment since the adaptive 2x2 MIMO antenna configuration, which was used in the initial network deployment provides poor estimates for average BER performance as compared to 4x4 antenna configuration which seem less affected in the presence of multiple interferers.
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.
Distributed User Selection in Network MIMO Systems with Limited Feedback
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.
Robotic Mobile System's Performance-Based MIMO-OFDM Technology
Directory of Open Access Journals (Sweden)
Omar Alani
2009-10-01
Full Text Available In this paper, a predistortion neural network (PDNN architecture has been imposed to the Sniffer Mobile Robot (SNFRbot that is based on spatial multiplexed wireless Orthogonal Frequency Division Multiplexing (OFDM transmission technology. This proposal is used to improve the system performance by combating one of the main drawbacks that is encountered by OFDM technology; Peak-to-Average Power Ratio (PAPR. Simulation results show that using PDNN resulted in better PAPR performance than the previously published work that is based on linear coding, such as Low Density Parity Check (LDPC codes and turbo encoding whether using flat fading channel or a Doppler spread channel.
A Survey on Frequency Synchronization in MIMO Systems%无线通信MIMO中的频率同步
Institute of Scientific and Technical Information of China (English)
邓凯
2012-01-01
分别针对无线通信集中式多入多出（MIMO）和分布式MIMO系统,对频偏估计和频偏补偿这两个方面的基本原理和研究现状进行了详细分析,总结出已有研究的不足之处在于对分布式MIMO中的频偏估计以及分布式MIMO-OFDM（正交频分复用）中的频偏补偿的研究尚不完善,指出未来可能的研究方向应主要集中在分布式MIMO中基于一般系统模型的频偏估计方法和分布式MIMO-OFDM中具有实用价值的低复杂度频偏补偿方法两个方面.%The fundamentals and state of the art of the estimation and compensation of carrier frequency offset(CFOs) for multi-input multi-output(MIMO) systems with co-located antennas and distributed antennas were addressed respectively.By analyzing the disadvantages of the existing research,it is indicated that the study on the CFO estimation for distributed MIMO and the CFO compensation for distributed MIMO-OFDM(orthogonal frequency division multiplexing) appear incomplete.So the further research interest may include the CFO estimation methods based on the general system model for distributed MIMO and the practical low-complexity CFO compensation methods for distributed MIMO-OFDM.
Improved adaptive fuzzy control for MIMO nonlinear time-delay systems
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
This paper presents an improved observer-based indirect adaptive fuzzy control scheme for multiinput-multioutput (MIMO) nonlinear time-delay systems.The control scheme synthesizes adaptive fuzzy control with adaptive fuzzy identification.An observer is designed to observe the system state,and an identifier is developed to identify the unknown parts of the system.The update laws for parameters utilize two types of errors in the adaptive time-delay fuzzy logic systems,the observation error and the identificat...
Directory of Open Access Journals (Sweden)
Leila Sahraoui
2013-10-01
Full Text Available An OFDM system is combined with multiple-input multiple-output (MIMO in order to increase thediversity gain and system capacity over the time variant frequency-selective channels. However, a majordrawback of MIMO-OFDM system is that the transmitted signals on different antennas might exhibit highpeak-to-average power ratio (PAPR.In this paper, we present a PAPR analysis reduction of space-timeblock-coded (STBC MIMO-OFDM system for 4G wireless networks. Several techniques have been used toreduce the PAPR of the (STBC MIMOOFDM system: clipping and filtering, partial transmit sequence(PTS and selected mapping (SLM. Simulation results show that clipping and filtering provides a betterPAPR reduction than the others methods and only SLM technique conserve the PAPR reduction inreception part of signal
Mohammed, H. A.; Sibley, M. J. N.; Mather, P. J.
2012-05-01
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.
Feedback linearization of piecewise linear systems
Camlibel, Kanat; Ustoglu, Ilker
2005-01-01
One of the classical problems of nonlinear systems and control theory is feedback linearization. Its obvious motivation is that one can utilize linear control theory if the nonlinear system at hand is linearizable by feedback. This problem is well-understood for the smooth nonlinear systems. In the
Linear systems theory revisited
Willigenburg, van L.G.; Koning, de W.L.
2008-01-01
This paper investigates and clarifies how different definitions of reachability, observability, controllability, reconstructability and minimality that appear in the control literature, may be equivalent or different, depending on the type of linear system. The differences are caused by (1) whether
Time-Frequency Based Channel Estimation for High-Mobility OFDM Systems-Part I: MIMO Case
Önen, Erol; Akan, Aydın; Chaparro, LuisF
2010-12-01
Multiple-input multiple-output (MIMO) systems hold the potential to drastically improve the spectral efficiency and link reliability in future wireless communications systems. A particularly promising candidate for next-generation fixed and mobile wireless systems is the combination of MIMO technology with Orthogonal Frequency Division Multiplexing (OFDM). OFDM has become the standard method because of its advantages over single carrier modulation schemes on multipath, frequency selective fading channels. Doppler frequency shifts are expected in fast-moving environments, causing the channel to vary in time, that degrades the performance of OFDM systems. In this paper, we present a time-varying channel modeling and estimation method based on the Discrete Evolutionary Transform to obtain a complete characterization of MIMO-OFDM channels. Performance of the proposed method is evaluated and compared on different levels of channel noise and Doppler frequency shifts.
Laguerre-Volterra model and architecture for MIMO system identification and output prediction.
Li, Will X Y; Xin, Yao; Chan, Rosa H M; Song, Dong; Berger, Theodore W; Cheung, Ray C C
2014-01-01
A generalized mathematical model is proposed for behaviors prediction of biological causal systems with multiple inputs and multiple outputs (MIMO). The system properties are represented by a set of model parameters, which can be derived with random input stimuli probing it. The system calculates predicted outputs based on the estimated parameters and its novel inputs. An efficient hardware architecture is established for this mathematical model and its circuitry has been implemented using the field-programmable gate arrays (FPGAs). This architecture is scalable and its functionality has been validated by using experimental data gathered from real-world measurement.
Power allocation for MIMO-OFDM systems with multi-user decoupling and scheduling
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
A power allocation scheme for multi-user multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with channel state information (CSI) on transmitter and receiver is pressed. Multi-user power allocation can be decoupled into single user power allocation throughout null space mapping of multi-user channel and power allocation can be performed throughout spatial-spectral water-filling for per user. To deal with more users in system and fading correlation, scheduling is performed to maintain the gain of power allocation. The proposed scheme can substantially improve system's spectral efficiency with low omplexity. Simulation results validate the accuracy of theoretic analyses.
Capacity of MIMO LAS-CDMA System Under Correlating Multi-Path Fading Channels
Institute of Scientific and Technical Information of China (English)
WANG Jun-xuan; RAO Wen-yuan; LI Dao-ben
2005-01-01
Capacity of MIMO LAS-CDMA systems under multi-path fading channels with two different correlating models were studied in the paper. Influences of the two models parameters on capacity were analyzed. The numerical results present that: according to the Various Scattering Environments correlating model, when the inner-elements distance of antennas array is large than 0.5λ, correlation almost does not take from the system capacity; for the Salz-Winter correlating model, the spread angle at receiver is the other key factor, it also influence the system capacity greatly.
Checking Capacity for MIMO Configurations
DEFF Research Database (Denmark)
Thaysen, Jesper; Jakobsen, Kaj Bjarne
2007-01-01
Wireless system capacity can be added by increasing the number of antennas in a MIMO setup or by carefully optimizing the performance of a smaller number of antennas.......Wireless system capacity can be added by increasing the number of antennas in a MIMO setup or by carefully optimizing the performance of a smaller number of antennas....
Robust Adaptive Neural Control of a Class of MIMO Nonlinear Systems
Institute of Scientific and Technical Information of China (English)
HU Tingliang; ZHU Jihong; SUN Zengqi
2007-01-01
In this paper we present a robust adaptive control for a class of uncertain continuous time multiple input multiple output (MIMO) nonlinear systems. Multiple multi-layer neural networks are employed to approximate the uncertainty of the nonlinear functions,and robustifying control terms are used to compensate for approximation errors.All parameter adaptive laws and robustifying control terms are derived based on Lyapunov stability analysis so that, under appropriate assumptions, semiglobal stability of the closed - loop system is guaranteed, and the tracking error asymptotically converges to zero. Simulations performed on a two-link robot manipulator illustrate the approach and its performance.
BLIND EQUALIZATION OF MIMO SYSTEMS BASED ON ORTHOGONAL CONSTANT MODULUS ALGORITHM
Institute of Scientific and Technical Information of China (English)
无
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.
Zhang, Cong; Xiong, Zhihua; Ye, Hao
2014-07-01
In system identification, a data set needs to be informative to guarantee that the identification criterion has a unique global minimum asymptotically and the parameter estimation is consistent. In this paper, we study the informativity of the data set in a multiple-input and multiple-output (MIMO) networked control system (NCS), which contains possible network-induced delays, packet dropout, transmission scheduling, or a combination of these factors in network transmission. Moreover, to guarantee the data set of this MIMO NCS to be informative, a group of conditions for network transmission and controller's proportional term are developed. Finally, simulation studies are given to illustrate the result.
Sub-channel shared resource allocation for multi-user distributed MIMO-OFDM systems
Institute of Scientific and Technical Information of China (English)
Na-e ZHENG; You ZHOU; Han-ying HU; Sheng WANG
2014-01-01
Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output or-thogonal frequency division multiplexing (MIMO-OFDM) systems. Recent studies have focused primarily on traditional cen-tralized systems or distributed antenna systems (DASs), and usually assumed that one sub-carrier or sub-channel is exclusively occupied by one user. To promote system performance, we propose a sub-channel shared resource allocation algorithm for multi- user distributed MIMO-OFDM systems. Each sub-channel can be shared by multiple users in the algorithm, which is different from previous algorithms. The algorithm assumes that each user communicates with only two best ports in the system. On each sub-carrier, it allocates a sub-channel in descending order, which means one sub-channel that can minimize signal to leakage plus noise ratio (SLNR) loss is deleted until the number of remaining sub-channels is equal to that of receiving antennas. If there are still sub-channels after all users are processed, these sub-channels will be allocated to users who can maximize the SLNR gain. Simulations show that compared to other algorithms, our proposed algorithm has better capacity performance and enables the system to provide service to more users under the same capacity constraints.
基于GAIC的MIMO-OFDM信道估计%GAIC Based Approach for Channel Estimation in MIMO-OFDM Systems
Institute of Scientific and Technical Information of China (English)
赵俊义; 贾世楼; 孟维晓
2008-01-01
对于多径稀疏的多输入多输出正交频分复用(Multiple-input and muItipIe-output orthogonal frequency division multiplexing,MIMO-OFDM)信道,提出了基于广义Akaike信息论准则(Generalized Akaike information criterion,GAIC)的MIMO-OFDM系统实用的信道估计算法,该算法能够估计出信道的长度和每径信道的时延,降低加性白噪声对信道估计的影响,提高信道估计的精度.通过仿真,与最小二来(Least squares,LS)算法和离散傅里叶变换(Discrete Fourier transform,DFT)算法相比较,大大地降低了信道的估计误差,提高了系统性能,且信道稀疏性越强,性能改善越好.
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.
Robust Transceiver Design for AF MIMO Relay Systems with Column Correlations
Xing, Chengwen; Wu, Yik-Chung; Ma, Shaodan; Kuang, Jingming
2012-01-01
In this paper, we investigate the robust transceiver design for dual-hop amplify-and-forward (AF) MIMO relay systems with Gaussian distributed channel estimation errors. Aiming at maximizing the mutual information under imperfect channel state information (CSI), source precoder at source and forwarding matrix at the relay are jointly optimized. Using some elegant attributes of matrix-monotone functions, the structures of the optimal solutions are derived first. Then based on the derived structure an iterative waterfilling solution is proposed. Several existing algorithms are shown to be special cases of the proposed solution. Finally, the effectiveness of the proposed robust design is demonstrated by simulation results.
Low complexity variational bayes iterative reviver for MIMO-OFDM systems
DEFF Research Database (Denmark)
Xiong, Chunlin; Wang, Hua; Zhang, Xiaoying;
2009-01-01
A low complexity iterative receiver is proposed in this paper for MIMO-OFDM systems in time-varying multi-path channel based on the variational Bayes (VB) method. According to the VB method, the estimation algorithms of the signal distribution and the channel distribution are derived...... for the receiver. With the aid of the soft-output QRD-M algorithm, whose complexity is fixed and relatively low, the signal distribution can be obtained conveniently. In particular, a sequential channel estimation algorithm, which completely avoids the computation of matrix inversion and multiplication...
The PARAFAC-MUSIC Algorithm for DOA Estimation with Doppler Frequency in a MIMO Radar System
Directory of Open Access Journals (Sweden)
Nan Wang
2014-01-01
Full Text Available The PARAFAC-MUSIC algorithm is proposed to estimate the direction-of-arrival (DOA of the targets with Doppler frequency in a monostatic MIMO radar system in this paper. To estimate the Doppler frequency, the PARAFAC (parallel factor algorithm is firstly utilized in the proposed algorithm, and after the compensation of Doppler frequency, MUSIC (multiple signal classification algorithm is applied to estimate the DOA. By these two steps, the DOA of moving targets can be estimated successfully. Simulation results show that the proposed PARAFAC-MUSIC algorithm has a higher accuracy than the PARAFAC algorithm and the MUSIC algorithm in DOA estimation.
Robust Beamforming for Amplify-and-Forward MIMO Relay Systems Based on Quadratic Matrix Programming
Xing, Chengwen; Wu, Yik-Chung; Ng, Tung-Sang
2010-01-01
In this paper, robust transceiver design based on minimum-mean-square-error (MMSE) criterion for dual-hop amplify-and-forward MIMO relay systems is investigated. The channel estimation errors are modeled as Gaussian random variables, and then the effect are incorporated into the robust transceiver based on the Bayesian framework. An iterative algorithm is proposed to jointly design the precoder at the source, the forward matrix at the relay and the equalizer at the destination, and the joint design problem can be efficiently solved by quadratic matrix programming (QMP).
Low complexity symbol-wise beamforming for MIMO-OFDM systems
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.
SUBSPACE-BASED NOISE VARIANCE AND SNR ESTIMATION FOR MIMO OFDM SYSTEMS
Institute of Scientific and Technical Information of China (English)
无
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.
Institute of Scientific and Technical Information of China (English)
朱勇旭; 易芝玲; 吴斌; 周玉梅
2014-01-01
针对无线局域网(WLAN)多输入多输出和正交频分复用(MIMO-OFDM)系统中矩阵的QR分解预处理的延时问题，提出一种分布式脉动阵列处理器(DSAP)进行QR分解预处理。该处理器通过脉动阵列边界单元和内部单元中流水线CORDIC计算，实现子载波信道矩阵的QR分解分布式处理，不同子载波QR分解分布于脉动阵列边界单元和内部单元中CORDIC流水线计算的不同级。与串行脉动阵列处理器(SSAP)相比，在复杂度几乎没有增加情况下，DSAP结构充分利用时钟周期，分解延时约为SSAP结构的8%。在SMIC 0.18μm CMOS工艺下，该分布式脉动阵列结构应用于2发2收MIMO-OFDM数模混合芯片中，芯片测试验证结果表明，数据处理延时能有效减少。%To reduce the delay of QR-decomposition in WLAN (wireless local area network) MIMO-OFDM (multiple input multiple output and orthogonal frequency division multiplexing) systems, a distributed systolic array processor (DSAP) is proposed. The structure uses the coordinate rotation digital computer (CORDIC) in the boundary and internal cells of systolic array, and distributes the QR-decomposition of different sub-carriers into the different stages of the pipelining operation of CORDIC in systolic array. Compared with serial systolic array processor (SSAP), the clock periods can be put to great use in the DSAP, and the delay is reduced by 92%with the same complexity. In SMIC 0.18 μm CMOS technology, a ×22 analog -digital mixed MIMO-OFDM chip with DSAP has been implemented, and the test results show that it can reduce the delay of data processing effectively.
MIMO Radar System for Respiratory Monitoring Using Tx and Rx Modulation with M-Sequence Codes
Miwa, Takashi; Ogiwara, Shun; Yamakoshi, Yoshiki
The importance of respiratory monitoring systems during sleep have increased due to early diagnosis of sleep apnea syndrome (SAS) in the home. This paper presents a simple respiratory monitoring system suitable for home use having 3D ranging of targets. The range resolution and azimuth resolution are obtained by a stepped frequency transmitting signal and MIMO arrays with preferred pair M-sequence codes doubly modulating in transmission and reception, respectively. Due to the use of these codes, Gold sequence codes corresponding to all the antenna combinations are equivalently modulated in receiver. The signal to interchannel interference ratio of the reconstructed image is evaluated by numerical simulations. The results of experiments on a developed prototype 3D-MIMO radar system show that this system can extract only the motion of respiration of a human subject 2m apart from a metallic rotatable reflector. Moreover, it is found that this system can successfully measure the respiration information of sleeping human subjects for 96.6 percent of the whole measurement time except for instances of large posture change.
Space-Frequency Block Code with Matched Rotation for MIMO-OFDM System with Limited Feedback
Directory of Open Access Journals (Sweden)
Thushara D. Abhayapala
2009-01-01
Full Text Available This paper presents a novel matched rotation precoding (MRP scheme to design a rate one space-frequency block code (SFBC and a multirate SFBC for MIMO-OFDM systems with limited feedback. The proposed rate one MRP and multirate MRP can always achieve full transmit diversity and optimal system performance for arbitrary number of antennas, subcarrier intervals, and subcarrier groupings, with limited channel knowledge required by the transmit antennas. The optimization process of the rate one MRP is simple and easily visualized so that the optimal rotation angle can be derived explicitly, or even intuitively for some cases. The multirate MRP has a complex optimization process, but it has a better spectral efficiency and provides a relatively smooth balance between system performance and transmission rate. Simulations show that the proposed SFBC with MRP can overcome the diversity loss for specific propagation scenarios, always improve the system performance, and demonstrate flexible performance with large performance gain. Therefore the proposed SFBCs with MRP demonstrate flexibility and feasibility so that it is more suitable for a practical MIMO-OFDM system with dynamic parameters.
DEFF Research Database (Denmark)
Kotterman, Wim; Pedersen, Gert F.; Szini, Istvan Janos
2016-01-01
in science and technology (COST) IC1004, discussions are generally held in an easier atmosphere than in standardisation bodies. Contributions to a broader understanding of OTAtesting of multi-antenna systems and its implications are welcomed as much as investigations of particular technologies or concepts....... Such contributions come from industry and academia. Compared to earlier work in, for instance in COST Action 2100, the focus has shifted from RF performance (the present OTA standard) to overall device performance as seen by the user, without regarding any specific hardware/subsystem performance. This also means....... The targeted application of MIMO OTA in standardisation is the conformance testing cycle, currently targeting RF performance only and not production testing. In this Chapter, contributions over the project duration are documented and resumed in a coherent way....
Efficient Sphere Detector Algorithm for Massive MIMO using GPU Hardware Accelerator
Arfaoui, Mohamed-Amine
2016-06-01
To further enhance the capacity of next generation wireless communication systems, massive MIMO has recently appeared as a necessary enabling technology to achieve high performance signal processing for large-scale multiple antennas. However, massive MIMO systems inevitably generate signal processing overheads, which translate into ever-increasing rate of complexity, and therefore, such system may not maintain the inherent real-time requirement of wireless systems. We redesign the non-linear sphere decoder method to increase the performance of the system, cast most memory-bound computations into compute-bound operations to reduce the overall complexity, and maintain the real-time processing thanks to the GPU computational power. We show a comprehensive complexity and performance analysis on an unprecedented MIMO system scale, which can ease the design phase toward simulating future massive MIMO wireless systems.
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
Impact of Non-Idealities System on Spatial Correlation in a Multi-Probe Based MIMO OTA Setup
DEFF Research Database (Denmark)
Fan, Wei; Nielsen, Jesper Ødum; Carreño, Xavier
2013-01-01
. This paper investigates the extent to which we can emulate the channel spatial characteristics inside the test zone where the device under test is located. The focus is on performance deterioration introduced by system non-idealities on spatial correlation emulation in practical MIMO OTA test systems....
On the Linear Precoder Design for MIMO Channels with Finite-Alphabet Inputs and Statistical CSI
Zeng, Weiliang; Wang, Mingxi; Lu, Jianhua
2011-01-01
This paper investigates the linear precoder design that maximizes the average mutual information of multiple-input multiple-output channels with finite-alphabet inputs and statistical channel state information known at the transmitter. This linear precoder design is an important open problem and is extremely difficult to solve: First, average mutual information lacks closed-form expression and involves complicated computations; Second, the optimization problem over precoder is nonconcave. This study explores the solution to this problem and provides the following contributions: 1) A closed-form lower bound of average mutual information is derived. It achieves asymptotic optimality at low and high signal-to-noise ratio regions and, with a constant shift, offers an accurate approximation to the average mutual information; 2) The optimal structure of the precoder is revealed, and a unified two-step iterative algorithm is proposed to solve this problem. Numerical examples show the convergence and the efficacy of ...
BER PERFORMANCE COMPARISON OF MIMO SYSTEMS USING OSTBC WITH ZF AND ML DECODING
Directory of Open Access Journals (Sweden)
Zenitha Rehman
2014-12-01
Full Text Available Multiple Input Multiple Output (MIMO systems with multiple antenna elements at both transmitter and receiver ends are an efficient solution for wireless communication systems. They provide high data rates by exploiting the spatial domain under the constraints of limited bandwidth and transmit power. Space-Time Block Coding (STBC is a MIMO transmit strategy which exploits transmit diversity and provides high reliability. Implementation of orthogonal space-time block codes (OSTBCs for a two transmitter–two receiver system under AWGN (Additive White Gaussian Noise channel and flat fading channel is performed. Alamouti code is employed for the STBC. The modulation techniques used are BPSK, QPSK and 16-QAM. Decoding is done using the Zero Forcing (ZF algorithm and Maximum Likelihood (ML algorithm. The BER Performance of each modulation scheme is compared with the un-coded version of the same. Performance comparison between the two decoding techniques is also done. It is found that ML detection offers a slightly better performance for BPSK and QPSK system than ZF detection.
Long, Lijun; Zhao, Jun
2016-05-02
In this paper, the problem of adaptive neural output-feedback control is addressed for a class of multi-input multioutput (MIMO) switched uncertain nonlinear systems with unknown control gains. Neural networks (NNs) are used to approximate unknown nonlinear functions. In order to avoid the conservativeness caused by adoption of a common observer for all subsystems, an MIMO NN switched observer is designed to estimate unmeasurable states. A new switched observer-based adaptive neural control technique for the problem studied is then provided by exploiting the classical average dwell time (ADT) method and the backstepping method and the Nussbaum gain technique. It effectively handles the obstacle about the coexistence of multiple Nussbaum-type function terms, and improves the classical ADT method, since the exponential decline property of Lyapunov functions for individual subsystems is no longer satisfied. It is shown that the technique proposed is able to guarantee semiglobal uniformly ultimately boundedness of all the signals in the closed-loop system under a class of switching signals with ADT, and the tracking errors converge to a small neighborhood of the origin. The effectiveness of the approach proposed is illustrated by its application to a two inverted pendulum system.
An Overview of Signal Processing Techniques for Millimeter Wave MIMO Systems
Heath, Robert W.; Gonzalez-Prelcic, Nuria; Rangan, Sundeep; Roh, Wonil; Sayeed, Akbar M.
2016-04-01
Communication at millimeter wave (mmWave) frequencies is defining a new era of wireless communication. The mmWave band offers higher bandwidth communication channels versus those presently used in commercial wireless systems. The applications of mmWave are immense: wireless local and personal area networks in the unlicensed band, 5G cellular systems, not to mention vehicular area networks, ad hoc networks, and wearables. Signal processing is critical for enabling the next generation of mmWave communication. Due to the use of large antenna arrays at the transmitter and receiver, combined with radio frequency and mixed signal power constraints, new multiple-input multiple-output (MIMO) communication signal processing techniques are needed. Because of the wide bandwidths, low complexity transceiver algorithms become important. There are opportunities to exploit techniques like compressed sensing for channel estimation and beamforming. This article provides an overview of signal processing challenges in mmWave wireless systems, with an emphasis on those faced by using MIMO communication at higher carrier frequencies.
Optimal Superimposed Training Sequences for Channel Estimation in MIMO-OFDM Systems
Directory of Open Access Journals (Sweden)
Ratnam V. Raja Kumar
2010-01-01
Full Text Available In this work an iterative time domain Least Squares (LS based channel estimation method using superimposed training (ST for a Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM system over time varying frequency selective fading channels is proposed. The performance of the channel estimator is analyzed in terms of the Mean Square Estimation Error (MSEE and its impact on the uncoded Bit Error Rate (BER of the MIMO-OFDM system is studied. A new selection criterion for the training sequences that jointly optimizes the MSEE and the BER of the OFDM system is proposed. Chirp based sequences are proposed and shown to satisfy the same. These are compared with the other sequences proposed in the literature and are found to yield a superior performance. The sequences, one for each transmitting antenna, offers fairness through providing equal interference in all the data carriers unlike earlier proposals. The effectiveness of the mathematical analysis presented is demonstrated through a comparison with the simulation studies. Experimental studies are carried out to study and validate the improved performance of the proposed scheme. The scheme is applied to the IEEE 802.16e OFDM standard and a case is made with the required design of the sequence.
Principal and key technology of MIMO-OFDM system%MIMO-OFDM系统原理及其关键技术
Institute of Scientific and Technical Information of China (English)
陈宏
2006-01-01
介绍了第四代移动通信系统中的MIMO-OFDM技术,阐述了OFDM、MIMO技术及MIMO-OFDM系统的基本原理与特点,并介绍了MIMO空时信号处理技术、MIMO OFDM同步、信道估计、信道编码以及自适应技术.
Park, Kihong
2013-02-01
In this paper, we study a two-hop relaying network consisting of one source, one destination, and three amplify-and-forward (AF) relays with multiple antennas. To compensate for the capacity prelog factor loss of 1/2$ due to the half-duplex relaying, alternate transmission is performed among three relays, and the inter-relay interference due to the alternate relaying is aligned to make additional degrees of freedom. In addition, suboptimal linear filter designs at the nodes are proposed to maximize the achievable sum rate for different fading scenarios when the destination utilizes a minimum mean-square error filter. © 1967-2012 IEEE.
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.
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.
The architecture of blind equalizer for MIMO free space optical communication system
Li, Hongwei; Huang, Yongmei
2016-10-01
The free space optical (FSO) communication system has attracted many researchers from different countries, owning to its advantages such as high security, high speed and anti-interference. Among all kinds of the channels of the FSO communication system, the atmosphere channel is very difficult to deal with for two typical disadvantages at least. The one is the scintillation of the optical carrier intensity caused by the atmosphere turbulence and the other is the multipath effect by the optical scattering. A lot of studies have shown that the MIMO (Multiple Input Multiple Output) technology can overcome the scintillation of the optical carrier through the atmosphere effectively. So the background of this paper is a MIMO system which includes multiple optical transmitting antennas and multiple optical receiving antennas. A number of particles such as hazes, water droplets and aerosols exit in the atmosphere widely. When optical carrier meets these particles, the scattering phenomenon is inevitable, which leads to the multipath effect. As a result, a optical pulse transmitted by the optical transmitter becomes wider, to some extent, when it gets to the optical receiver due to the multipath effect. If the information transmission rate is quite low, there is less relationship between the multipath effect and the bit error rate (BER) of the communication system. Once the information transmission rate increases to a high level, the multipath effect will produce the problem called inter symbol inference (ISI) seriously and the bit error rate will increase severely. In order to take the advantage of the FSO communication system, the inter symbol inference problem must be solved. So it is necessary to use the channel equalization technology. This paper aims at deciding a equalizer and designing suitable equalization algorithm for a MIMO free space optical communication system to overcome the serious problem of bit error rate. The reliability and the efficiency of
Crystallized Rate Regions for MIMO Transmission
Directory of Open Access Journals (Sweden)
Debbah Merouane
2010-01-01
Full Text Available When considering the multiuser SISO interference channel, the allowable rate region is not convex and the maximization of the aggregated rate of all the users by the means of transmission power control becomes inefficient. Hence, a concept of the crystallized rate regions has been proposed, where the time-sharing approach is considered to maximize the sumrate.In this paper, we extend the concept of crystallized rate regions from the simple SISO interference channel case to the MIMO/OFDM interference channel. As a first step, we extend the time-sharing convex hull from the SISO to the MIMO channel case. We provide a non-cooperative game-theoretical approach to study the achievable rate regions, and consider the Vickrey-Clarke-Groves (VCG mechanism design with a novel cost function. Within this analysis, we also investigate the case of OFDM channels, which can be treated as the special case of MIMO channels when the channel transfer matrices are diagonal. In the second step, we adopt the concept of correlated equilibrium into the case of two-user MIMO/OFDM, and we introduce a regret-matching learning algorithm for the system to converge to the equilibrium state. Moreover, we formulate the linear programming problem to find the aggregated rate of all users and solve it using the Simplex method. Finally, numerical results are provided to confirm our theoretical claims and show the improvement provided by this approach.
COMBINED TRANSMIT ANTENNA SELECTION AND DETECTION OVER SPATIAL CORRELATED MIMO SYSTEMS
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper a method that combines transmit antenna selection and reduced-constellation detection in spatially correlated Multi-Input Multi-Output (MIMO) fading channels is presented. To mitigate the performance degradation caused by the use of antenna selection that is based on correlation among columns, an iterative receiver scheme that uses only a subset of the constellation points close to the expected symbol value estimated in the previous iteration is proposed. The size of the subset can adapt to the maximum correlation of the sub-matrix after the simple antenna selection. Furthermore, the error rate performance of the scheme under linear Minimum Mean Square Error (MMSE) or Ordered Successive Interference Cancellation (OSIC) for the first run detection and different interleaver lengths is investigated while the transmit antenna selection is considered. The simulation results show a significant advantage both for implementation complexity and for error rate performance under a fixed data rate.
Institute of Scientific and Technical Information of China (English)
WANG Jian; YANG Xun; LI Dao-ben
2009-01-01
This article proposes a time/frequency synchronization algorithm in the multiple input multiple output (MIMO) systems, in which the perfect complete generalized complementary orthogonal loosely synchronous code groups are used as the synchronization sequence. The synchronization algorithm is divided into four stages: 1) synchronization in time domain by signal autocorrelation; 2) synchronization in frequency domain by fast Fourier transform (FFT); 3) multipath dissociation using coherent detection and fine time synchronization; 4) fine frequency offset estimation by phase rotation. As per the perfect complete generalized complementary orthogonal loosely synchronous code groups, the cross-correlation and out-of-phase auto-correlation for any relative shift between any two codes is always zero. This ideal property makes the time/frequency synchronization algorithm simple and efficient. The simulation results show that even in the multipath fast fading channel with low signal noise ratio (SNR), the MIMO system can get synchronized both in the time domain and frequency domain with high stability and reliability.
Performance Improvement in Spatially Multiplexed MIMO Systems over Weibull-Gamma Fading Channel
Tiwari, Keerti; Saini, Davinder S.; Bhooshan, Sunil V.
2016-11-01
In multiple-input multiple-output (MIMO) systems, spatial demultiplexing at the receiver has its own significance. Thus, several detection techniques have been investigated. There is a tradeoff between computational complexity and optimal performance in most of the detection techniques. One of the detection techniques which gives improved performance and acceptable level of complexity is ordered successive interference cancellation (OSIC) with minimum mean square error (MMSE). However, optimal performance can be achieved by maximum likelihood (ML) detection but at a higher complexity level. Therefore, MMSE-OSIC with candidates (OSIC2) detection is recommended as a solution. In this paper, spatial multiplexed (SM) MIMO systems are considered to evaluate error performance with different detection techniques such as MMSE-OSIC, ML and MMSE-OSIC2 in a composite fading i. e. Weibull-gamma (WG) fading environment. In WG distribution, Weibull and gamma distribution represent multipath and shadowing effects, respectively. Simulation results illustrate that MMSE-OSIC2 detection technique gives the improved symbol error rate (SER) performance which is similar to ML performance and its complexity level approaches to MMSE-OSIC.
Implementation of MIMO and AMC Techniques in WiMAX Network based VANET System
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Prabhakar D. Dorge
2016-02-01
Full Text Available Vehicular Ad-hoc Networks (VANETs are expected to implement wireless technologies such as Dedicated Short Range Communications (DSRC which is a category of Wi-Fi. Other candidates of long distance wireless technologies are cellular, satellite, and WiMAX. VANETs can be viewed as component of the Intelligent Transportation Systems (ITS. This paper presents the implementation of Multiple Inputs Multiple Outputs (MIMO and Adaptive Modulation and Coding (AMC techniques in WiMAX based Vehicular Ad-hoc Network. This designed system provides multiple radio channels in between transmitter and receiver for transmission and reception of the data by using the concept of MIMO technology. Also AMC provides the selection of different modulation techniques depending on the signal to noise ratio of the channel. These two techniques provide the significant change in the throughput, delay, jitter, and packet delivery ratio and packet loss ratio than existing vehicular ad-hoc network. WiMAX based VANET provides high speed, low cost per bit and large coverage area.
Time-reversal techniques for MISO and MIMO wireless communication systems
Fouda, Ahmed E.; Teixeira, Fernando L.; Yavuz, Mehmet E.
2012-10-01
We consider the application of different time-reversal (TR) signal processing and beamforming techniques to multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) wireless communication systems. Conventional TR beamforming provides spatial focusing at the intended receiver; however, it does not yield perfect channel equalization. Time-reversed pilot can be normalized to provide perfect equalization at the expense of power level. This equalization is particularly important for high data rates where the bit error rate performance is dominated by internal noise due to intersymbol interference. To increase physical layer covertness, TR beamforming is combined with the multiple-signal-classification (MUSIC) technique to produce null fields at eavesdroppers. This technique is also applied to MIMO setups to eliminate interuser interference and hence increase system capacity. Differential TR is used to obtain and update pilot signals for passive moving receivers, i.e., those that cannot (or do not) transmit pilot signals. Time-reversed differential backscattered signal is able to provide satisfactory spatial and temporal focusing at the moving receiver.
Zhou, Liang; Shimizu, Masahiko
In this paper, we study low complexity transceiver for double space time transmit diversity (DSTTD) and orthogonal frequency division multiplexing (OFDM) system with antenna shuffling. Firstly, we propose a novel antenna shuffling method based on the criterion of minimizing the condition number of channel correlation matrix. The condition number is an indicator about the quality of the channel. By selecting the minimum of condition number which has better channel quality, consequently, a linear detector with respect to this new channel may achieve better performance results. A low complexity variant of the condition number calculation is also proposed, and it is shown that this criterion can be reduced to the minimum mean square error (MMSE) based criterion. Furthermore, the weighted soft decision Viterbi decoding is applied to mitigate noise enhancement inherent to zero forcing (ZF) and MMSE linear receivers and improve error rate performance. Next, we propose an algorithm to reduce the amount of feedback by exploiting the fact that the channel frequency responses across OFDM subcarriers are correlated. In the proposed algorithm, subcarriers are clustered in blocks, which are allocated the same shuffling pattern with the largest number of the shuffling patterns in the cluster. This way, the signaling overhead can be reduced in comparison with each subcarrier based feedback. Extensive simulations show that the proposed techniques for DSTTD-OFDM system outperform other existing techniques under both uncorrelated and highly spatial correlated frequency selective MIMO fading channels.
Ahmad Ansari, Ejaz; Rajatheva, Nandana
Although the topic of multiple-input multiple-output (MIMO) based orthogonal frequency division multiplexing (OFDM) over different fading channels is well investigated, its closed form symbol error rate (SER) expressions and performance results employing orthogonal space time block codes (OSTBCs) over uncorrelated frequency-selective Nakagami-m fading channels are still not available. The closed form expressions are extremely useful for evaluating system's performance without carrying out time consuming simulations. Similarly, the performance results are also quite beneficial for determining the system's performance in the sense that many practical wireless standards extensively employ MIMO-OFDM systems in conjunction with M-ary quadrature amplitude modulation (M-QAM) constellation. This paper thus, derives exact closed form expressions for the SER of M-ary Gray-coded one and two dimensional constellations when an OSTBC is employed and Nt transmit antennas are selected for transmission over frequency-selective Nakagami-m fading channels. For this purpose, first an exact closed-form of average SER expression of OSTBC based MIMO-OFDM system for M-ary phase shift keying (M-PSK) using traditional probability density function (PDF) approach is derived. We then compute exact closed form average SER expressions for M-ary pulse amplitude modulation (M-PAM) and M-QAM schemes by utilizing this generalized result. These expressions are valid over both frequency-flat and frequency-selective Nakagami-m fading MIMO channels and can easily be evaluated without using any numerical integration methods. We also show that average SER of MIMO-OFDM system using OSTBC in case of frequency-selective Rayleigh fading channels remains independent to the number of taps, L of that fading channel and the performance of the same system for two-tap un-correlated Rayleigh and Nakagami-m fading channels is better than that of the correlated one. Moreover, Monte Carlo simulation of MIMO-OFDM system
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Jorswieck E. A.
2004-01-01
Full Text Available The capacity of a cellular multiuser MIMO system depends on various parameters, for example, the system structure, the transmit and receive strategies, the channel state information at the transmitter and the receiver, and the channel properties. Recently, the main focus of research was on single-user MIMO systems, their channel capacity, and their error performance with space-time coding. In general, the capacity of a cellular multiuser MIMO system is limited by additive white Gaussian noise, intracell interference from other users within the cell, and intercell interference from users outside the considered cell. We study one point-to-point link, on which interference acts. The interference models the different system scenarios and various parameters. Therefore, we consider three scenarios in which the noise is subject to different constraints. A general trace constraint is used in the first scenario. The noise covariance matrix eigenvalues are kept fixed in the second scenario, and in the third scenario the entries on the diagonal of the noise covariance matrix are kept fixed. We assume that the receiver as well as the transmitter have perfect channel state information. We solve the corresponding minimax programming problems and characterize the worst-case noise and the optimal transmit strategy. In all scenarios, the achievable capacity of the MIMO system with worst-case noise is equal to the capacity of some MIMO system in which either the channels are orthogonal or the transmit antennas are not allowed to cooperate or in which no channel state information is available at the transmitter. Furthermore, the minimax expressions fulfill a saddle point property. All theoretical results are illustrated by examples and numerical simulations.
Power Scaling of Uplink Massive MIMO Systems With Arbitrary-Rank Channel Means
Zhang, Qi; Jin, Shi; Wong, Kai-Kit; Zhu, Hongbo; Matthaiou, Michail
2014-10-01
This paper investigates the uplink achievable rates of massive multiple-input multiple-output (MIMO) antenna systems in Ricean fading channels, using maximal-ratio combining (MRC) and zero-forcing (ZF) receivers, assuming perfect and imperfect channel state information (CSI). In contrast to previous relevant works, the fast fading MIMO channel matrix is assumed to have an arbitrary-rank deterministic component as well as a Rayleigh-distributed random component. We derive tractable expressions for the achievable uplink rate in the large-antenna limit, along with approximating results that hold for any finite number of antennas. Based on these analytical results, we obtain the scaling law that the users' transmit power should satisfy, while maintaining a desirable quality of service. In particular, it is found that regardless of the Ricean $K$-factor, in the case of perfect CSI, the approximations converge to the same constant value as the exact results, as the number of base station antennas, $M$, grows large, while the transmit power of each user can be scaled down proportionally to $1/M$. If CSI is estimated with uncertainty, the same result holds true but only when the Ricean $K$-factor is non-zero. Otherwise, if the channel experiences Rayleigh fading, we can only cut the transmit power of each user proportionally to $1/\\sqrt M$. In addition, we show that with an increasing Ricean $K$-factor, the uplink rates will converge to fixed values for both MRC and ZF receivers.
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Ko ChiChung
2009-01-01
Full Text Available This paper proposes a turbo joint channel estimation, synchronization, and decoding scheme for coded multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM systems. The effects of carrier frequency offset (CFO, sampling frequency offset (SFO, and channel impulse responses (CIRs on the received samples are analyzed and explored to develop the turbo decoding process and vector recursive least squares (RLSs algorithm for joint CIR, CFO, and SFO tracking. For burst transmission, with initial estimates derived from the preamble, the proposed scheme can operate without the need of pilot tones during the data segment. Simulation results show that the proposed turbo joint channel estimation, synchronization, and decoding scheme offers fast convergence and low mean squared error (MSE performance over quasistatic Rayleigh multipath fading channels. The proposed scheme can be used in a coded MIMO-OFDM transceiver in the presence of multipath fading, carrier frequency offset, and sampling frequency offset to provide a bit error rate (BER performance comparable to that in an ideal case of perfect synchronization and channel estimation over a wide range of SFO values.
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2009-03-01
Full Text Available This paper proposes a turbo joint channel estimation, synchronization, and decoding scheme for coded multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM systems. The effects of carrier frequency offset (CFO, sampling frequency offset (SFO, and channel impulse responses (CIRs on the received samples are analyzed and explored to develop the turbo decoding process and vector recursive least squares (RLSs algorithm for joint CIR, CFO, and SFO tracking. For burst transmission, with initial estimates derived from the preamble, the proposed scheme can operate without the need of pilot tones during the data segment. Simulation results show that the proposed turbo joint channel estimation, synchronization, and decoding scheme offers fast convergence and low mean squared error (MSE performance over quasistatic Rayleigh multipath fading channels. The proposed scheme can be used in a coded MIMO-OFDM transceiver in the presence of multipath fading, carrier frequency offset, and sampling frequency offset to provide a bit error rate (BER performance comparable to that in an ideal case of perfect synchronization and channel estimation over a wide range of SFO values.
A cross-layer resource allocation scheme for spatial multiplexing-based MIMO-OFDMA systems
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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.
Spatial correlation characterization of a uniform circular array in 3D MIMO systems
Nadeem, Qurrat-Ul-Ain
2016-08-11
In this paper, we consider a uniform circular array (UCA) of directional antennas at the base station (BS) and the mobile station (MS) and derive an exact closed-form expression for the spatial correlation present in the 3D multiple-input multiple-output (MIMO) channel constituted by these arrays. The underlying method leverages the mathematical convenience of the spherical harmonic expansion (SHE) of plane waves and the trigonometric expansion of Legendre and associated Legendre polynomials. In contrast to the existing results, this generalized closed-form expression is independent of the form of the underlying angular distributions and antenna patterns. Moreover, the incorporation of the elevation dimension into the antenna pattern and channel model renders the proposed expression extremely useful for the performance evaluation of 3D MIMO systems in the future. Verification is achieved with the help of simulation results, which highlight the dependence of the spatial correlation on channel and array parameters. An interesting interplay between the mean angle of departure (AoD), angular spread and the positioning of antennas in the array is demonstrated. © 2016 IEEE.
VLSI architecture of a K-best detector for MIMO-OFDM wireless communication systems
Energy Technology Data Exchange (ETDEWEB)
Jian Haifang; Shi Yin, E-mail: jhf@semi.ac.c [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)
2009-07-15
The K-best detector is considered as a promising technique in the MIMO-OFDM detection because of its good performance and low complexity. In this paper, a new K-best VLSI architecture is presented. In the proposed architecture, the metric computation units (MCUs) expand each surviving path only to its partial branches, based on the novel expansion scheme, which can predetermine the branches' ascending order by their local distances. Then a distributed sorter sorts out the new K surviving paths from the expanded branches in pipelines. Compared to the conventional K-best scheme, the proposed architecture can approximately reduce fundamental operations by 50% and 75% for the 16-QAM and the 64-QAM cases, respectively, and, consequently, lower the demand on the hardware resource significantly. Simulation results prove that the proposed architecture can achieve a performance very similar to conventional K-best detectors. Hence, it is an efficient solution to the K-best detector's VLSI implementation for high-throughput MIMO-OFDM systems.
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.
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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.
Performance of Antenna Selection in MIMO System Using Channel Reciprocity with Measured Data
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Peerapong Uthansakul
2011-01-01
Full Text Available The channel capacity of MIMO system increases as a function of antenna pairs between transmitter and receiver but it suffers from multiple expensive RF chains. To reduce cost of RF chains, antenna selection (AS method can offer a good tradeoff between expense and performance. For a transmitting AS system, channel state information (CSI feedback is required to choose the best subset of available antennas. However, the delay and error in feedback channel are the most dominant factors to degrade performances. In this paper, the concept of AS method using reciprocal CSI instead of feedback channel is proposed. The capacity performance of proposed system is investigated by own developing Testbed. The obtained results indicate that the reciprocity technique offers a capacity close to a system with perfect CSI and gains a higher capacity than a system without AS method. This benefit is from 0.9 to 2.2 bps/Hz at SNR 10 dB.
Evaluation of the Performance of the Distributed Phased-MIMO Sonar.
Pan, Xiang; Jiang, Jingning; Wang, Nan
2017-01-11
A broadband signal model is proposed for a distributed multiple-input multiple-output (MIMO) sonar system consisting of two transmitters and a receiving linear array. Transmitters are widely separated to illuminate the different aspects of an extended target of interest. The beamforming technique is utilized at the reception ends for enhancement of weak target echoes. A MIMO detector is designed with the estimated target position parameters within the general likelihood rate test (GLRT) framework. For the high signal-to-noise ratio case, the detection performance of the MIMO system is better than that of the phased-array system in the numerical simulations and the tank experiments. The robustness of the distributed phased-MIMO sonar system is further demonstrated in localization of a target in at-lake experiments.
Radio-over-optical waveguide system-on-wafer for massive delivery capacity 5G MIMO access networks
Binh, Le N.
2017-01-01
Delivering maximum information capacity over MIMO antennae systems beam steering is critical so as to achieve the flexibility via beam steering, maximizing the number of users or community of users in Gb/s rate per user over distributed cloud-based optical-wireless access networks. This paper gives an overview of (i) demands of optical - wireless delivery with high flexibility, especially the beam steering of multi-Tbps information channels to information hungry community of users via virtualized beam steering MIMO antenna systems at the free-license mmW region; (ii) Proposing a novel photonic planar integrated waveguide systems composing several passive and active, passive and amplification photonic devices so as to generate mmW carrier and embedded baseband information channels to feed to antenna elements; (iii) Integration techniques to generate a radio over optical waveguide (RoOW) system-on-wafer (SoW) comprising MIMO planar antenna elements and associate photonic integrated circuits for both up- and down- links; (iv) Challenges encountered in the implementation of the SoW in both wireless and photonic domains; (v) Photonic modulation techniques to achieve maximum transmission capacity per wavelength per MIMO antenna system. (vi) A view on control-feedback systems for fast and accurate generation of phase pattern for MIMO beam steering via a bank of optical phase modulators to mmW carrier phases and their preservation in the converted mmW domain . (vi) The overall operational principles of the novel techniques and technologies based on the coherent mixing of two lightwave channels The entire SoW can be implemented on SOI Si-photonic technology or via hybrid integration. These technological developments and their pros- and cons- will be discussed to achieve 50Tera-bps over the extended 110 channel Cband single mode fiber with mmW centered at 58.6GHz and 7GHz free-license band.
Direct adaptive control for a class of MIMO nonlinear discrete-time systems
Institute of Scientific and Technical Information of China (English)
Lei Li; Zhizhong Mao
2014-01-01
This paper considers the problem of adaptive con-trol for a class of multiple input multiple output (MIMO) nonlinear discrete-time systems based on input-output model with unknown interconnections between subsystems. Based on the Taylor ex-pand technology, an equivalent model in affine-like form is derived for the original nonaffine nonlinear system. Then a direct adap-tive neural network (NN) control er is implemented based on the affine-like model. By finding an orthogonal matrix to tune the NN weights, the closed-loop system is proven to be semiglobal y uni-formly ultimately bounded. The σ-modification technique is used to remove the requirement of persistence excitation during the adaptation. The control performance of the closed-loop system is guaranteed by suitably choosing the design parameters.
Printed MIMO antenna engineering
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
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H. A. Hashim
2015-01-01
Full Text Available This paper presents a comparative study of fuzzy controller design for the twin rotor multi-input multioutput (MIMO system (TRMS considering most promising evolutionary techniques. These are gravitational search algorithm (GSA, particle swarm optimization (PSO, artificial bee colony (ABC, and differential evolution (DE. In this study, the gains of four fuzzy proportional derivative (PD controllers for TRMS have been optimized using the considered techniques. The optimization techniques are developed to identify the optimal control parameters for system stability enhancement, to cancel high nonlinearities in the model, to reduce the coupling effect, and to drive TRMS pitch and yaw angles into the desired tracking trajectory efficiently and accurately. The most effective technique in terms of system response due to different disturbances has been investigated. In this work, it is observed that GSA is the most effective technique in terms of solution quality and convergence speed.
Synchronisation of high-order MIMO nonlinear systems using distributed neuro-adaptive control
Ghiti Sarand, Hassan; Karimi, Bahram
2016-07-01
This paper addresses synchronisation problem of high-order multi-input/multi-output (MIMO) multi-agent systems. Each agent has unknown nonlinear dynamics and is subject to uncertain external disturbances. The agents must follow a reference trajectory. An adaptive distributed controller based on relative information of neighbours of each agent is designed to solve the problem for any undirected connected communication topology. A radial basis function neural network is used to represent the controller's unknown structure. Lyapunov stability analysis is employed to guarantee stability of the overall system. By the theoretical analysis, the closed-loop control system is shown to be uniformly ultimately bounded. Finally, simulations are provided to show effectiveness of the proposed control method against uncertainty and disturbances.
Shahnazi, Reza
2015-01-01
An adaptive fuzzy output feedback controller is proposed for a class of uncertain MIMO nonlinear systems with unknown input nonlinearities. The input nonlinearities can be backlash-like hysteresis or dead-zone. Besides, the gains of unknown input nonlinearities are unknown nonlinear functions. Based on universal approximation theorem, the unknown nonlinear functions are approximated by fuzzy systems. The proposed method does not need the availability of the states and an observer based on strictly positive real (SPR) theory is designed to estimate the states. An adaptive robust structure is used to cope with fuzzy approximation error and external disturbances. The semi-global asymptotic stability of the closed-loop system is guaranteed via Lyapunov approach. The applicability of the proposed method is also shown via simulations.
Interference Mitigation for Cognitive Radio MIMO Systems Based on Practical Precoding
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.
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Xiaoyu Dang
2012-01-01
Full Text Available By combining adaptive modulation and automatic repeat request, a cross-layer design (CLD scheme for MIMO system with antenna selection (AS and imperfect feedback is presented, and the corresponding performance is studied. Subject to a target packet loss rate and fixed power constraint, the variable switching thresholds of fading gain are derived. According to these results, and using mathematical manipulation, the average spectrum efficiency (SE and packet error rate (PER of the system are further derived. As a result, closed-form expressions of the average SE and PER are obtained, respectively. These expressions include the expressions under perfect channel state information as special cases and provide good performance evaluation for the system. Numerical results show that the proposed CLD scheme with antenna selection has higher SE than the existing CLD scheme with space-time block coding, and the CLD scheme with variable switching thresholds outperforms that with conventional-fixed switching thresholds.
Observer Design for a Class of MIMO Nonlinear Systems (Preprint)
2006-06-01
without control), because it covers an important class of dynamic systems such as the Van der Pol equation and Duffing oscillator [5], [13] — both of...1992. [5] J. Guckenheimer and P. Holmes, Nonlinear oscillations , dynamical systems, and bifurcations of vector fields, Springer, NY, 1983. [6] A
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Dr. Sandip Nemade
2013-09-01
Full Text Available The main goal is to access the appropriateness of OFDM as a modulation technique for a fixed wireless phone system. Several of the main factors affecting the performance of a OFDM system, were measured including multipath delay spread, channel noise, distortion of the signal (clipping, and timing requirements. This paper focuses on how MIMO OFDM-CDMA systems are capable of achieving diversity gains significantly larger than that of the day to day system
PERBANDINGAN PERFORMANSI SISTEM MC-SS MIMO DENGAN OFDM MIMO
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Ni Putu Eka Apsari Yuniari
2016-11-01
Full Text Available The combination of the system has been doing to improve the reliability of wireless communication. One parameter that indicates the reliability of wireless communication is to reduce the value of BER. The 4G technology uses OFDM transmission technique combined with MIMO antenna technique. Other than that, the combination between transmission technique can also be done, by incorporating the concept of multicarrier (OFDM and spread spectrum as known as multicarrier spread spectrum (MC-SS. The combination of OFDM, spread spectrum, and MIMO are supported by the advantages of each of these techniques is expected to give a good performance in supporting the reliability of wireless communication. This research aimed to compare the value of BER vs. Eb/No between MC-SS MIMO system and OFDM MIMO system. The test of these systems are conducted by simulation using MatLab 2012 which aims to provide an overview of other related technologies are capable of providing wireless communication reliability. The results of the simulation shows that the value of BER on MC-SS MIMO system is lower than MIMO OFDM system for all Eb/No. This condition also applies to AWGN and Rayleigh Fading channel. Kombinasi sistem dilakukan untuk meningkatkan kehandalan komunikasi wireless. Salah satu parameter yang menunjukkan kehandalan komunikasi wireless adalah dengan mengurangi nilai BER. Pada teknologi 4G menggunakan kombinasi teknik transmisi OFDM dengan teknik antena MIMO. Selain daripada itu, kombinasi antar teknik transmisi juga dapat dilakukan, yaitu dengan menggabungkan konsep multicarrier OFDM dengan spread spectrum yang selanjutnya dikenal dengan multicarrier spread spectrum (MC-SS. Kombinasi antara OFDM, spread spectrum, dan MIMO yang didukung oleh kelebihan dari masing-masing teknik tersebut diharapkan mampu memberikan performansi yang baik dalam mendukung kehandalan komunikasi wireless. Dalam paper ini akan dibandingkan performansi menurut BER vs. Eb/No dari sistem
A Novel Iterative Receiver Based on Extrinsic Information Update for MIMO Systems
Institute of Scientific and Technical Information of China (English)
LIN Wen-feng; HE Chen
2007-01-01
A novel iterative receiver for multiple input multiple output (MIMO) systems was introduced.Its basis concept is that the reliability of extrinsic information will be strengthened with continuous iterations.Extrinsic information of present iteration is added with prior information of last iteration to obtain performance gain.The simulation results show that the improved iterative receiver can approach the 5th iteration performance of conventional soft interference cancellation (SIC)-minimum mean square error (MMSE) iterative receiver after the 2nd iteration with less computational complexity.Compared with conventional iterative receiver, the improved iterative receiver has 1dB performance gain at bit error rate (BER) of 10-5, with four transmit antennas and four receive antennas system.
Optimization of energy efficiency for the full-duplex massive MIMO systems
Institute of Scientific and Technical Information of China (English)
Xinhua Wang; Ju Liu; Chao Zhai; Pengbo Xing; Lina Zheng
2016-01-01
The energy efficiency (EE) for the ful-duplex mas-sive multi-input multi-output (MIMO) system is investigated. Given the transmit powers of both the uplink and the downlink, the closed-form solutions of the optimal number of antennas and the maximum EE are achieved in the high regime of the signal-to-noise ratio (SNR). It is shown that the optimal num-ber of antennas and the maximum EE gets larger with the increase in user numbers. To further improve the EE, an op-timization algorithm with low complexity is proposed to jointly determine the number of antennas and the transmit powers of both the uplink and the downlink. It is shown that, the pro-posed algorithm can achieve the system performance very close to the exhaustive search.
Performance Analysis of Optimal Single Stream Beamforming in MIMO Dual-Hop AF Systems
Zhong, Caijun; Jin, Shi; Wong, Kai Kit
2012-01-01
This paper investigates the performance of optimal single stream beamforming schemes in multiple-input multiple-output (MIMO) dual-hop amplify-and-forward (AF) systems. Assuming channel state information is not available at the source and relay, the optimal transmit and receive beamforming vectors are computed at the destination, and the transmit beamforming vector is sent to the transmitter via a dedicated feedback link. Then, a set of new closed-form expressions for the statistical properties of the maximum eigenvalue of the resultant channel is derived, i.e., the cumulative density function (cdf), probability density function (pdf) and general moments, as well as the first order asymptotic expansion and asymptotic large dimension approximations. These analytical expressions are then applied to study three important performance metrics of the system, i.e., outage probability, average symbol error rate and ergodic capacity. In addition, more detailed treatments are provided for some important special cases, ...
MIMO Modeling Approach for a Small Photovoltaic Reverse Osmosis Desalination System
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A.B Chaaben
2011-01-01
Full Text Available The most widely used desalination processes are based on membrane separation via reverse osmosis (RO which has become an important process for desalting seawater and cleaning brackish water. The use of these processes requires an efficient control system. Consequently, it is necessary to establish a dynamic model of the system with experimental validation. This paper deals with a new modelling approach of a small photovoltaic reverse osmosis (PV-RO desalination unit. The proposed model considers the unit as a Multi Input Multi Output (MIMO process. The relations between the output variables and the input variables are given by the use of empirical transfer matrix. A state model of the unit is also given. Some experimental results are presented to validate the proposed model. As result, the obtained unit model can be easily used for a process control loop implementation in order to assure an optimum operating condition and to reduce the water product cost.
Leakage-based precoding for MU-MIMO VLC systems under optical power constraint
Chen, Jiaxuan; Wang, Qi; Wang, Zhaocheng
2017-01-01
In this paper, we investigate a multiuser multiple-input multiple-output (MU-MIMO) system for indoor visible light communication (VLC), in which precoding is conducted under optical power constraint rather than electrical power constraint. Leakage-based precoding designed by maximizing signal-to-leakage-plus-noise ratio (SLNR) is adopted to suppress the multiuser interference under optical power constraint and power allocation is proposed to maximize the throughput of the system. Simulations demonstrate the performance gain of optimal power allocation and indicate that the leakage-based precoding scheme outperforms zero forcing counterpart when the channel is highly correlated and still works well when the number of transmitters is less than that of receivers.
Combined simplified maximum likelihood and sphere decoding algorithm for MIMO system
Institute of Scientific and Technical Information of China (English)
ZHANG Lei; YUAN Ting-ting; ZHANG Xin; YANG Da-cheng
2008-01-01
In this article, a new system model for sphere decoding (SD) algorithm is introduced. For the multiple- input multiple-out (MIMO) system, a simplified maximum likelihood (SML) decoding algorithm is proposed based on the new model. The SML algorithm achieves optimal maximum likelihood (ML) performance, and drastically reduces the complexity as compared to the conventional SD algorithm. The improved algorithm is presented by combining the sphere decoding algorithm based on Schnorr-Euchner strategy (SE-SD) with the SML algorithm when the number of transmit antennas exceeds 2. Compared to conventional SD, the proposed algorithm has low complexity especially at low signal to noise ratio (SNR). It is shown by simulation that the proposed algorithm has performance very close to conventional SD.
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.
Hashemi, Mahnaz; Ghaisari, Jafar; Askari, Javad
2015-07-01
This paper investigates an adaptive controller for a class of Multi Input Multi Output (MIMO) nonlinear systems with unknown parameters, bounded time delays and in the presence of unknown time varying actuator failures. The type of considered actuator failure is one in which some inputs may be stuck at some time varying values where the values, times and patterns of the failures are unknown. The proposed approach is constructed based on a backstepping design method. The boundedness of all the closed-loop signals is guaranteed and the tracking errors are proved to converge to a small neighborhood of the origin. The proposed approach is employed for a double inverted pendulums benchmark and a chemical reactor system. The simulation results show the effectiveness of the proposed method.
Improving Energy Efficiency Through Multimode Transmission in the Downlink MIMO Systems
Xu, Jie; Yu, Chengwen
2011-01-01
Adaptively adjusting system parameters including bandwidth, transmit power and mode to maximize the "Bits per-Joule" energy efficiency (BPJ-EE) in the downlink MIMO systems with imperfect channel state information at the transmitter (CSIT) is considered in this paper. By mode we refer to choice of transmission schemes i.e. singular value decomposition (SVD) or block diagonalization (BD), active transmit/receive antenna number and active user number. We derive optimal bandwidth and transmit power for each dedicated mode at first. During the derivation, accurate capacity estimation strategies are proposed to cope with the imperfect CSIT caused capacity prediction problem. Then, an ergodic capacity based mode switching strategy is proposed to further improve the BPJ-EE, which provides insights on the preferred mode under given scenarios. Mode switching compromises different power parts, exploits the tradeoff between the multiplexing gain and the imperfect CSIT caused inter-user interference, improves the BPJ-EE ...
Directory of Open Access Journals (Sweden)
Dr.T.V.S.Prasad Gupta
2014-10-01
Full Text Available We consider the large scale MIMO systems in which the number of users are gradually increased at that time the receiving antennas performance also decreased gradually. In contrast, almost no analytical results are available for macro diversity systems where both the sources and receive antennas are widely separated. Here, receive antennas experience unequal average SNRs from a source and receiver antenna receives a different average SNR from each source. Although this is an extremely difficult problem,In this paper, we provide approximate distributions for the output SNR of a ZF receiver and the output signal to interference plus noise ratio (SINR of an MMSE receiver. In addition, simple high SNR approximations are provided for the symbol error rate (SER of both receivers assuming M-PSK or M-QAM modulations .For better performance of receivers we can also implement the MMSE and ZF analysis in Wimax networks.
Nonlinear precoding for VBLAST in MIMO-MC-CDMA systems.%MIMO-MC-CDMA系统分层空时非线性预编码
Institute of Scientific and Technical Information of China (English)
傅洪亮; 陶勇; 张元
2011-01-01
针对垂直分层空时方案(VBLAST)传统检测存在误层传输效应及复杂度高的问题,提出了一种多用户MIMO-MC-CD-MA下行链路系统中基于QR分解的VBLAST非线性模代数预编码算法,该算法首先采用QR分解获得预编码矩阵,然后在发射端MC-CDMA子载波信道间进行非线性模代数THP预编码,可以有效地消除分层空时码的误层传输效应.在接收端采用迫零与最小均方误差准则,降低了下行接收机的复杂度.仿真结果表明,提出的算法比传统检测算法有效改善了系统的误码性能.%Considering the error propagation effect and high complexity of vertical bell labs layered space time codes,a novel nonlinear module algebra precoding algorithm based on QR decomposition for VBLAST in multi-user MIMO-MC-CDMA downlink system is proposed, QR decomposition is used for precoding matrix,the nonlinear module algebra THP precoding is used between sub-carrier channels of MC-CDMA to eliminate interference from other signals at the transmitter, and can eliminate the error propagation effect of layered space-time codes effectively. At the receiver, ZF and MMSE criterion are used for detection,and the complexity of the downlink receiver can be reduced. Simulation results show that the proposed algorithm is better than the traditional algorithms in the system BER performance.
PILOT DECONTAMINATION THROUGH PILOT SEQUENCE HOPPING IN MASSIVE MIMO SYSTEMS
DEFF Research Database (Denmark)
2015-01-01
The invention relates to a system for determining channel coefficients of channels in a wireless cellular network. The wireless cellular network comprises a plurality of cells wherein each cell comprises a base station configured to communicate with users within the cell and wherein a communicati...
Robust direct adaptive fuzzy control for nonlinear MIMO systems
Institute of Scientific and Technical Information of China (English)
ZHANG Huaguang; ZHANG Mingjun
2006-01-01
For a class of nonlinear multi-input multi-output systems with uncertainty, a robust direct adaptive fuzzy control scheme was proposed. The feedback control law and adaptive law for parameters were derived based on Lyapunov design approach. The overall control scheme can guarantee that the tracking error converges in the small neighborhood of origin, and all signals of the closed-loop system are uniformly bounded. The main advantage of the proposed control scheme is that in each subsystem only one parameter vector needs to be adjusted on-line in the adaptive mechanism, and so the on-line computing burden is reduced. In addition, the proposed control scheme is a smooth control with no chattering phenomena. A simulation example was proposed to demonstrate the effectiveness of the proposed control algorithm.
PILOT DECONTAMINATION THROUGH PILOT SEQUENCE HOPPING IN MASSIVE MIMO SYSTEMS
DEFF Research Database (Denmark)
2015-01-01
The invention relates to a system for determining channel coefficients of channels in a wireless cellular network. The wireless cellular network comprises a plurality of cells wherein each cell comprises a base station configured to communicate with users within the cell and wherein a communication...... path between one of the users and one of the base stations define one of the channels. The system comprises a pilot generation unit configured to assign pilot sequences randomly among the users and a pilot processing unit configured to filter the pilot sequences received from a user of interest so...... that the channel coefficient of the channel of the user of interest is determined. The pilot sequences received from the user of interest are contaminated by other non-orthogonal or identical pilot sequences from other users of the cell of interest or other cells. The filter is configured so that the contamination...
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.
Diversity in MIMO System%MIMO系统中的分集技术
Institute of Scientific and Technical Information of China (English)
韩丽君
2012-01-01
Diversity plays an important role in the MIMO system. At first, wireless multi-diameter fading channel is analyzed theoretically, and on this basis, the principle of diversity techniques is given, then by introducing diversity technique and comparing the advantages and disadvantages of several typical sub-set technologies. The space diversity technology not only can improve the transmission of reliable nature but also not bring the advantages of any loss in bandwidth utilization, and thus it became a diversity techniques for MIMO systems. Finally it is also shown by simulation that spatial diversity techniques can reduce the system bit error rate in slow Rayleigh fading channels.%分集技术在MIMO系统中具有十分重要的地位.首先从理论上分析了无线多径衰落信道.在此基础上给出分集技术原理.然后通过介绍分集技术并比较了几种典型的分集技术的优缺点.得出空间分集技术具有提高传输的可靠性,且不会带来带宽利用率上的任何损失的优势.因而成为了MIMO系统中所采用的分集技术.最后通过仿真验证了在慢瑞利衰落信道中采用空间分集技术能够降低系统的误比特率.
Mou Chen; Rong Mei; Bin Jiang
2013-01-01
We propose a robust sliding mode control (SMC) scheme for a class of uncertain multi-input and multi-output (MIMO) nonlinear systems with the unknown external disturbance, the system uncertainty, and the backlash-like hysteresis. To tackle the continuous system uncertainty, the radial basis function (RBF) neural network is employed to approximate it. And then, combine the unknown external disturbance, and the unknown neural network approximation error with the affection caused by backlash-lik...
Xing, Chengwen; Wu, Yik-Chung; Ng, Tung-Sang
2010-01-01
In this paper, joint design of linear relay precoder and destination equalizer for dual-hop non-regenerative amplify-and-forward (AF) MIMO-OFDM systems under channel estimation errors is investigated. Second order moments of channel estimation errors in the two hops are first deduced. Then based on the Bayesian framework, joint design of linear robust precoder at the relay and equalizer at the destination is proposed to minimize the total mean-square-error (MSE) of the output signal at the destination. The optimal designs for both correlated and uncorrelated channel estimation errors are considered. The relationship with existing algorithms is also disclosed. Simulation results show that the proposed robust designs outperform the design based on estimated channel state information only.
Maximum MIMO System Mutual Information with Antenna Selection and Interference
Directory of Open Access Journals (Sweden)
Rick S. Blum
2004-05-01
Full Text Available Maximum system mutual information is considered for a group of interfering users employing single user detection and antenna selection of multiple transmit and receive antennas for flat Rayleigh fading channels with independent fading coefficients for each path. In the case considered, the only feedback of channel state information to the transmitter is that required for antenna selection, but channel state information is assumed at the receiver. The focus is on extreme cases with very weak interference or very strong interference. It is shown that the optimum signaling covariance matrix is sometimes different from the standard scaled identity matrix. In fact, this is true even for cases without interference if SNR is sufficiently weak. Further, the scaled identity matrix is actually that covariance matrix that yields worst performance if the interference is sufficiently strong.
Pilot Signal Design for Massive MIMO Systems: A Received Signal-To-Noise-Ratio-Based Approach
So, Jungho; Kim, Donggun; Lee, Yuni; Sung, Youngchul
2015-05-01
In this paper, the pilot signal design for massive MIMO systems to maximize the training-based received signal-to-noise ratio (SNR) is considered under two channel models: block Gauss-Markov and block independent and identically distributed (i.i.d.) channel models. First, it is shown that under the block Gauss-Markov channel model, the optimal pilot design problem reduces to a semi-definite programming (SDP) problem, which can be solved numerically by a standard convex optimization tool. Second, under the block i.i.d. channel model, an optimal solution is obtained in closed form. Numerical results show that the proposed method yields noticeably better performance than other existing pilot design methods in terms of received SNR.
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.
Digital transceiver design for two-way AF-MIMO relay systems with imperfect CSI
Hu, Chia-Chang; Chou, Yu-Fei; Chen, Kui-He
2013-09-01
In the paper, combined optimization of the terminal precoders/equalizers and single-relay precoder is proposed for an amplify-and-forward (AF) multiple-input multiple-output (MIMO) two-way single-relay system with correlated channel uncertainties. Both terminal transceivers and relay precoding matrix are designed based on the minimum mean square error (MMSE) criterion when terminals are unable to erase completely self-interference due to imperfect correlated channel state information (CSI). This robust joint optimization problem of beamforming and precoding matrices under power constraints belongs to neither concave nor convex so that a nonlinear matrix-form conjugate gradient (MCG) algorithm is applied to explore local optimal solutions. Simulation results show that the robust transceiver design is able to overcome effectively the loss of bit-error-rate (BER) due to inclusion of correlated channel uncertainties and residual self-interference.
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.
Approximation methods of mixed l 1/H2 optimization problems for MIMO discrete-time systems
Institute of Scientific and Technical Information of China (English)
李昇平
2004-01-01
The mixed l1/H2 optimization problem for MIMO (multiple input-multiple output) discrete-time systems is eonsidered. This problem is formulated as minimizing the l1-norm of a dosed-loop transfer matrix while maintaining the H2-norm of another closed-loop transfer matrix at prescribed level. The continuity property of the optimal value in respect to changes in the H2-norm constraint is studied. The existence of the optimal solutions of mixed l1/H2 problem is proved. Becatse the solution of the mixed l1/H2 problem is based on the scaled-Q method, it avoids the zero interpolation difficulties. The convergent upper and lower bounds can be obtained by solving a sequence of finite dimensional nonlinear programming for which many efficient numerical optimization algorithms exist.
Simultaneous Wireless Information and Power Transfer for MIMO Amplify-and-Forward Relay Systems
Benkhelifa, Fatma
2016-01-06
In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) for the two-hop Multiple-Input Multiple-Output (MIMO) Amplify-and-Forward (AF) relay communication systems with the multiantenna energy harvesting relay. We derive the optimal source and relay covariance matrices to characterize the achievable region between the sourcedestination rate and the harvested energy at the relay, namely Rate-Energy (R-E) region. In this context, we consider the ideal scenario where the energy harvester (EH) receiver and the information decoder (ID) receiver at the relay can simultaneously decode the information and harvest the energy at the relay. Then, we consider more practical schemes which are the power splitting (PS) and the time switching (TS) which separate the EH and ID transfer over the power domain and the time domain, respectively.
Cross layer scheduling for real-time traffic in multiuser MIMO-OFDMA systems
Institute of Scientific and Technical Information of China (English)
SUN Qiao-yun; TIAN Hui; DONG Kun; ZHANG Ping
2009-01-01
A novel cross layer scheduling algorithm is proposed for real-time (RT) traffic in multiuser downlink multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) wireless systems. The algorithm dynamically allocates resources in space, time and frequency domain based on channel state information (CSI), users' quality of service (QoS) requirements and queue state information (QSI). To provide higher data rate and spectrum efficiency, adaptive modulation and coding (AMC) is employed. The proposed algorithm can improve cell throughput and increase the number of users that can be supported while guaranteeing users' QoS requirements and fairness among all users. Simulation results indicate that the proposed algorithm can achieve superior performance.
Parameter estimation for MIMO system based on MUSIC and ML methods
Institute of Scientific and Technical Information of China (English)
Wei DONG; Jiandong LI; Zhuo LU; Linjing ZHAO
2009-01-01
The frequency offset and channel gain estimation problem for multiple-input multiple-output (MIMO)systems in the case of flat-fading channels is addressed.Based on the multiple signal classification (MUSIC) and the maximum likelihood (ML) methods, a new joint estimation algorithm of frequency offsets and channel gains is proposed. The new algorithm has three steps. A subset of frequency offsets is first estimated with the MUSIC algorithm. All frequency offsets in the subset are then identified with the ML method. Finally, channel gains are calculated with the ML estimator. The algorithm is a one-dimensional search scheme and therefore greatly decreases the complexity of joint ML estimation, which is essentially a multi-dimensional search scheme.
PERFORMANCE OF THE ZERO FORCING PRECODING MIMO BROADCAST SYSTEMS WITH CHANNEL ESTIMATION ERRORS
Institute of Scientific and Technical Information of China (English)
Wang Jing; Liu Zhanli; Wang Yan; You Xiaohu
2007-01-01
In this paper, the effect of channel estimation errors upon the Zero Forcing (ZF) precoding Multiple Input Multiple Output Broadcast (MIMO BC) systems was studied. Based on the two kinds of Gaussian estimation error models, the performance analysis is conducted under different power allocation strategies. Analysis and simulation show that if the covariance of channel estimation errors is independent of the received Signal to Noise Ratio (SNR), imperfect channel knowledge deteriorates the sum capacity and the Bit Error Rate (BER) performance severely. However, under the situation of orthogonal training and the Minimum Mean Square Error (MMSE) channel estimation, the sum capacity and BER performance are consistent with those of the perfect Channel State Information (CSI)with only a performance degradation.
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.
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.
An Approach to Optimum Joint Beamforming Design in a MIMO-OFDM Multiuser System
Directory of Open Access Journals (Sweden)
Pascual-Iserte Antonio
2004-01-01
Full Text Available This paper describes a multiuser scenario with several terminals acceding simultaneously to the same frequency channel. The objective is to design an optimal multiuser system that may be used as a comparative framework when evaluating other suboptimal solutions and to contribute to the already published works on this topic. The present work assumes that a centralized manager knows perfectly all the channel responses between all the terminals. According to this, the transmitters and receivers, using antenna arrays and leading to the so-called multiple-input-multiple-output (MIMO channels, are designed in a joint beamforming approach, attempting to minimize the total transmit power subject to quality of service (QoS constraints. Since this optimization problem is not convex, the use of the simulated annealing (SA technique is proposed to find the optimum solution.
Benkhelifa, Fatma
2015-05-01
In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) for a decode-and-forward (DF) multiple-input multiple-output (MIMO) relay system where the relay is an energy harvesting node. We consider the ideal scenario where both the energy harvesting (EH) receiver and information decoding (ID) receiver at the relay have access to the whole received signal and its energy. The relay harvests the energy while receiving the signal from the source and uses the harvested power to forward the signal to the destination. We obtain the optimal precoders at the source and the relay to maximize the achievable throughput rate of the overall link. In the numerical results, the effect of the transmit power at the source and the position of the relay between the source and the destination on the maximum achievable rate are investigated. © 2015 IEEE.
A best-first tree-searching approach for ML decoding in MIMO system
Shen, Chung-An
2012-07-28
In MIMO communication systems maximum-likelihood (ML) decoding can be formulated as a tree-searching problem. This paper presents a tree-searching approach that combines the features of classical depth-first and breadth-first approaches to achieve close to ML performance while minimizing the number of visited nodes. A detailed outline of the algorithm is given, including the required storage. The effects of storage size on BER performance and complexity in terms of search space are also studied. Our result demonstrates that with a proper choice of storage size the proposed method visits 40% fewer nodes than a sphere decoding algorithm at signal to noise ratio (SNR) = 20dB and by an order of magnitude at 0 dB SNR.
MIMO-OFDM系统的盲信道估计算法综述%An Overview of Blind Channel Estimation Algorithms for MIMO-OFDM Systems
Institute of Scientific and Technical Information of China (English)
张玲; 张贤达
2007-01-01
本文首先介绍了MIMO-OFDM系统模型,然后讨论了研究MIMO-OFDM移动通信系统信道估计的意义.紧接着对MIMO-OFDM系统目前存在的几种典型盲信道估计算法进行分析和讨论.最后总结和展望了MIMP-OFDM系统信道估计算法的研究方向和关键问题.
PAPR Reduction Using BPSO/PTS and STBC in MIMO OFDM System
Directory of Open Access Journals (Sweden)
Karima El Mouhib
2011-01-01
Full Text Available Problem statement: The Multiple Input Multiple Output (MIMO Orthogonal Frequency Division Multiplexing (OFDM system has been receiving a great attention, as one of solutions for achieving high speed, efficient and high-quality service for the wireless communications. However, the transmitted signal still has high PAPR because of OFDM characteristics. Many methods have been proposed to solve this problem, but the most of them decrease high Peak-to-Average Power Ratio (PAPR as well as the data rate. Approach: This proposal described a new suboptimal technique for reduction of the PAPR by combining two suitable methods for MIMO OFDM systems. The first method was based on Boolean Particle Swarm intelligence Optimization (BPSO applied to Partial transmit Sequence (PTS and the second was the Space Time Bloc Coding (STBC. Result: Apply only the PTS technique and independently on each transmitted antenna, was effective to reduce PAPR, but it requires high computation complexity. Therefore, the BPSO/PTS technique provided better performance and it was been promoted as an uncomplicated way for PAPR reduction. Thanks of the BPSO/PTS algorithm; the transmitted sequence was selected with minimizing the maximum PAPR over all transmission antennas. The simulations and the BER performance demonstrated that more inertia weight and phase weighting factor obtained better PAPR reduction performance without bringing much higher complexity. Conclusion: Results show that the added BPSO/PTS method to orthogonal space time bloc coding minimizes computational complexity cost as well as the PAPR and gives best optimal PTS performance in comparison with the conventional methods.
MIMO Networks: the Effects of Interference
Chiani, Marco; Shin, Hyundong
2008-01-01
Multiple-input/multiple-output (MIMO) systems promise enormous capacity increase and are being considered as one of the key technologies for future wireless networks. However, the decrease in capacity due to the presence of interferers in MIMO networks is not well understood. In this paper, we develop an analytical framework to characterize the capacity of MIMO communication systems in the presence of multiple MIMO co-channel interferers and noise. We consider the situation in which transmitters have no information about the channel and all links undergo Rayleigh fading. We first generalize the known determinant representation of hypergeometric functions with matrix arguments to the case when the argument matrices have eigenvalues of arbitrary multiplicity. This enables the derivation of the ergodic capacity expressions for MIMO systems in the presence of multiple MIMO interferers. Our analysis is valid for any number of interferers, each with arbitrary number of antennas having possibly unequal power levels....
Institute of Scientific and Technical Information of China (English)
郭爱煌; 肖法; 黄宇胜; 尚秀辉
2011-01-01
多输入多输出/智能天线(multiple input multiple output/smart antenna,MIMO/SA)系统是4G的关键技术之一,多天线的互耦效应是影响MIMO/SA多天线系统性能的主要问题.建立了MIMO与SA相结合的多天线系统模型,推导了互耦效应影响下空间相关系数和信道容量的表达式;通过电磁场数值计算和蒙特卡罗方法仿真MIMO/SA多天线系统的各态历经信道容量.结果表明:在典型的角度谱分布下改变天线间距,考虑互耦效应的信道容量围绕无互耦效应时的信道容量上下振荡;基站天线阵列间距增大信道容量持续增大,移动台天线阵列间距增大到0.5倍波长后信道容量基本保持不变;互耦效应增大信道的空域相关性,从而降低信道容量.%Multiple input multiple output and smart antenna (MIMO/SA) system is one of the key technologies for the fourth generation mobile communications system, mutual coupling is the main factor which affects the performance of MIMO/SA multi-antenna systems. A combination model of M1MO and SA is presented. With the existing of mutual coupling effects the expressions of spatial correlation and channel capacity are derived. The ergodic capacity of MIMO/SA multi-antenna systems is simulated using electromagnetic numeric method and Monte Carlo method. The results show that in the typical power azimuth spectrum distribution, the channel capacity which takes mutual coupling into account oscillates up and down around the channel capacity without mutual coupling while changing the distance of the antennas; the channel capacity increases continually while increasing the distance of base station antenna array; when antennas distance of the mobile station is farther than 0. 5 wavelength the channel capacity remains almost the same even though the antenna array distance increases; and mutual coupling increases the channel spatial correlation of MIMO/SA multi-antenna systems and thus reduces the channel capacity.
Qi, Jian
2011-03-01
In this paper, we investigate the joint effects of high-power amplifier (HPA) nonlinearity, in-phase/quadrature-phase (I/Q) imbalance and crosstalk, on the performance of multiple-input multiple-output (MIMO) transmit beamforming (TB) systems, and propose a compensation method for the three impairments together. The performance of the MIMO TB system equipped with the proposed compensation scheme is evaluated in terms of average symbol error probability and capacity when transmissions are performed over uncorrelated 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, length of pilot symbols and phase-shift keying modulation order. © 2011 IEEE.
Zhang, Shao-Jie; Qiu, Xiang-Wei; Jiang, Bin; Liu, Chun-Sheng
2015-03-01
This paper presents a new adaptive compensation control approach for a class of multi-input multi-output (MIMO) nonlinear systems with actuator failures. In order to enlarge the set of compensable actuator failures, an actuators grouping scheme based on multiple model switching and tuning (MMST) is proposed for the nonlinear MIMO minimum-phase systems with multiple actuator failures. Then, an adaptive compensation scheme based on prescribed performance bound (PPB) which characterises the convergence rate and maximum overshoot of the tracking error is designed for the systems to ensure closed-loop signal boundedness and asymptotic output tracking despite unknown actuator failures. Simulation results are given to show the effectiveness of the control design.
Shi, Wuxi; Luo, Rui; Li, Baoquan
2017-01-01
In this study, an adaptive fuzzy prescribed performance control approach is developed for a class of uncertain multi-input and multi-output (MIMO) nonlinear systems with unknown control direction and unknown dead-zone inputs. The properties of symmetric matrix are exploited to design adaptive fuzzy prescribed performance controller, and a Nussbaum-type function is incorporated in the controller to estimate the unknown control direction. This method has two prominent advantages: it does not require the priori knowledge of control direction and only three parameters need to be updated on-line for this MIMO systems. It is proved that all the signals in the resulting closed-loop system are bounded and that the tracking errors converge to a small residual set with the prescribed performance bounds. The effectiveness of the proposed approach is validated by simulation results.
使用复小波包的MIMO-OFDM无线系统%Complex wavelet packet based MIMO-OFDM wireless system
Institute of Scientific and Technical Information of China (English)
肖征荣; 余智; 赵绍刚; 吴伟陵
2004-01-01
为了在频率选择性信道中提供高速数据业务,提出了一种新的多入多出-正交频分复用系统MIMO-OFDM(Multi-Input Multi-Output-Orthogonal Frequency Division Multiplexing).该系统使用复小波包变换CWPT(Complex Wavelet Packet Transform)来实现OFDM,而不是使用传统的快速傅立叶变换FFT(Fast Fourier Transform).由于复小波包函数具有很好的特性,通过对有2个用户的MIMO-OFDM系统进行仿真的结果表明,基于CWPT的MIMO-OFDM系统性能要比使用传统的FFT的MIMO-OFDM 系统好,但是复杂度略高.
A Novel Mirror-Aided Non-imaging Receiver for Indoor 2x2 MIMO Visible Light Communication Systems
Park, Kihong
2017-06-07
Indoor visible light communication (VLC) systems are now possible because of advances in light emitting diode and laser diode technologies. These lighting technologies provide the foundation for multiple-input multiple-output (MIMO) data transmission through visible light. However, the channel matrix can be strongly correlated in indoor MIMO-VLC systems, preventing parallel data streams from being decoded. Here, in
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.
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.
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.
Directory of Open Access Journals (Sweden)
Vandendorpe Luc
2010-01-01
Full Text Available The problem of jointly optimizing the source precoder, relay transceiver, and destination equalizer has been considered in this paper for a multiple-input-multiple-output (MIMO amplify-and-forward (AF relay channel, where the channel estimates of all links are assumed to be imperfect. The considered joint optimization problem is nonconvex and does not offer closed-form solutions. However, it has been shown that the optimization of one variable when others are fixed is a convex optimization problem which can be efficiently solved using interior-point algorithms. In this context, an iterative technique with the guaranteed convergence has been proposed for the AF MIMO relay channel that includes the direct link. It has been also shown that, for the double-hop relay case without the receive-side antenna correlations in each hop, the global optimality can be confirmed since the structures of the source precoder, relay transceiver, and destination equalizer have closed forms and the remaining joint power allocation can be solved using Geometric Programming (GP technique under high signal-to-noise ratio (SNR approximation. In the latter case, the performance of the iterative technique and the GP method has been compared with simulations to ensure that the iterative approach gives reasonably good solutions with an acceptable complexity. Moreover, simulation results verify the robustness of the proposed design when compared to the nonrobust design that assumes estimated channels as actual channels.
Chalise, Batu K.; Vandendorpe, Luc
2010-12-01
The problem of jointly optimizing the source precoder, relay transceiver, and destination equalizer has been considered in this paper for a multiple-input-multiple-output (MIMO) amplify-and-forward (AF) relay channel, where the channel estimates of all links are assumed to be imperfect. The considered joint optimization problem is nonconvex and does not offer closed-form solutions. However, it has been shown that the optimization of one variable when others are fixed is a convex optimization problem which can be efficiently solved using interior-point algorithms. In this context, an iterative technique with the guaranteed convergence has been proposed for the AF MIMO relay channel that includes the direct link. It has been also shown that, for the double-hop relay case without the receive-side antenna correlations in each hop, the global optimality can be confirmed since the structures of the source precoder, relay transceiver, and destination equalizer have closed forms and the remaining joint power allocation can be solved using Geometric Programming (GP) technique under high signal-to-noise ratio (SNR) approximation. In the latter case, the performance of the iterative technique and the GP method has been compared with simulations to ensure that the iterative approach gives reasonably good solutions with an acceptable complexity. Moreover, simulation results verify the robustness of the proposed design when compared to the nonrobust design that assumes estimated channels as actual channels.
A Utility-Based Scheduling Scheme for MIMO-OFDMA Downlink Systems
Institute of Scientific and Technical Information of China (English)
Zhuang Liu; Xi Li; Hong Ji
2014-01-01
In this paper, a utility-based feedback delay-aware and buffer status-aware ( FABA ) scheduling scheme is proposed for downlink multiuser multiple-input multiple-output orthogonal frequency-division multiple-access ( MIMO-OFDMA ) systems. The FABA scheme allocates subcarriers to multiusers with an objective of not only maximizing the total system capacity but reducing the system packet loss rate as well. We design a utility function which consists of a feedback estimate module, a proportional fairness module and a buffer monitoring module. The feedback estimate module is used to improve the system throughput by utilizing the Automatic Repeat-reQuest ( ARQ) feedback information to combat the fast time-varying fading condition. The proportional fairness module can guarantee the scheduling fairness among users, and the buffer monitoring module can utilize the transmitting buffer status information to avoid high packet loss rate of the system caused by the system congestion. The FABA scheme then formulates the scheduling problem into a problem of overall system utility maximization. We solve the problem by using a heuristic algorithm with low computational complexity. The simulation results show that the proposed FABA scheme outperforms the existing algorithms in terms of the system throughput and the packet loss rate and can also guarantee the fairness demand among users.
Choi, Junil; Love, David J.; Bidigare, Patrick
2014-10-01
The concept of deploying a large number of antennas at the base station, often called massive multiple-input multiple-output (MIMO), has drawn considerable interest because of its potential ability to revolutionize current wireless communication systems. Most literature on massive MIMO systems assumes time division duplexing (TDD), although frequency division duplexing (FDD) dominates current cellular systems. Due to the large number of transmit antennas at the base station, currently standardized approaches would require a large percentage of the precious downlink and uplink resources in FDD massive MIMO be used for training signal transmissions and channel state information (CSI) feedback. To reduce the overhead of the downlink training phase, we propose practical open-loop and closed-loop training frameworks in this paper. We assume the base station and the user share a common set of training signals in advance. In open-loop training, the base station transmits training signals in a round-robin manner, and the user successively estimates the current channel using long-term channel statistics such as temporal and spatial correlations and previous channel estimates. In closed-loop training, the user feeds back the best training signal to be sent in the future based on channel prediction and the previously received training signals. With a small amount of feedback from the user to the base station, closed-loop training offers better performance in the data communication phase, especially when the signal-to-noise ratio is low, the number of transmit antennas is large, or prior channel estimates are not accurate at the beginning of the communication setup, all of which would be mostly beneficial for massive MIMO systems.
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 de...... 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....
Analysis and Realization on MIMO Channel Model
Directory of Open Access Journals (Sweden)
Liu Hui
2014-04-01
Full Text Available In order to build the MIMO (Multiple Input Multiple Output channel model based on IEEE 802.16, the way and analysis on how to build good MIMO channel model are described in this study. By exploiting the spatial freedom of wireless channels, MIMO systems have the potential to achieve high bandwidth efficiency, promoting MIMO to be a key technique in the next generation communication systems. As a basic researching field of MIMO technologies, MIMO channel modeling significantly serve to the performance evaluation of space-time encoding algorithms as well as system level calibration and simulation. Having the superiorities of low inner-antenna correlation and small array size, multi-polarization tends to be a promising technique in future MIMO systems. However, polarization characteristics have not yet been modeled well in current MIMO channel models, so establishing meaningful multi-polarized MIMO channel models has become a hot spot in recent channel modeling investigation. In this study, I have mainly made further research on the related theories in the channel models and channel estimation and implementation algorithms on the others’ research work.
Design of a Practical and Compact mm-Wave MIMO System with Optimized Capacity and Phased Arrays
Directory of Open Access Journals (Sweden)
Tommaso Cella
2014-01-01
Full Text Available In this paper we evaluate the feasibility of short range outdoor mm-wave MIMO links in the 70 GHz portion of the E-band (71–76 GHz. We use phased arrays in order to strongly reduce the impact of the multipath components, thus making the channel mainly line-of-sight (LOS. We design the array using a simple patch as a single element and simulate the performances for a 200 m link and a MIMO system with equal element spacing at the transmitter and the receiver. Each node of the MIMO system consists of a uniform rectangular array (URA where the single element is a patch antenna, in order to achieve higher gains and narrow beams. Such configuration is much more compact compared to the antennas currently employed for the same bandwidth. We optimize the interelement distances at the transmitter and the receiver and evaluate the capacity achievable with different array sizes. The results show that, for the proposed link budget, capacity up to 29 bit/s/Hz is achievable at a range of 200 m, with practical dimensions. We also show that the beamforming capabilities make the design much more flexible than the single reflector antenna systems. In the last part of the paper, we verify that our antenna can also operate in rainy conditions and longer ranges.
Institute of Scientific and Technical Information of China (English)
张艳语; 朱义君; 张水莲
2013-01-01
基于投影空间,提出了频率选择性MIMO (FS-MIMO)信道下一种实现块传输的收发联合设计方案.通过收发联合分离多径,把选择性信道转化为了若干正交的平坦MIMO等效信道,增加了系统设计的自由度.给出了一种容量最优的功率分配方案,推导了其误码率和信道容量的解析式.仿真结果验证了理论分析的正确性,该方案在高信噪比时与非块传输相比容量增益为L(多径数目).%Based on orthogonal projection,a transceiver scheme is proposed for MIMO block transmission over frequency-selective channel.By separating multi-path components,the selective MIMO channel is decomposed into L (the number of multi-path components) flat orthogonal MIMO effective channels,increasing degrees of freedom of system design.The analytical expressions of BER and capacity are given,based on proposed capacity-optimal power allocation.Simulation results show that compared with the existing non-block transmission,the capacity gain is L in high SNR regime.
MIMO-OFDM系统的IFD-SAGE信道估计算法%Improved FD-SAGE channel estimation algorithm for MIMO-OFDM system
Institute of Scientific and Technical Information of China (English)
高敬鹏; 赵旦峰; 周相超; 付芳
2013-01-01
针对MIMO-OFDM系统中频域的空间交替广义期望最大化（FD-SAGE）算法估计信道性能较差以及收敛速度慢的问题，提出了一种改进的FD-SAGE信道估计算法。该算法在FD-SAGE算法的基础上，通过对SAGE算法的潜在数据和不完全数据进行分解分析推导出一种修正的SAGE算法，同时在SAGE的更新数据信息时引入最大似然算法，进而提高系统的可靠性。理论研究和仿真结果表明，该算法以牺牲少量复杂度为代价，能较好地追踪信道变化且收敛速度较快，其性能优于传统的LS算法，信号检测采用最大似然算法时，在相同误比特率情况下与理想信道估计仅相差0.5 dB。%Aiming at the poor performance of Frequency Domain Space-Alternating Generalized Expectation-Maximization (FD-SAGE)algorithm in channel estimation and the slow convergence speed in the MIMO-OFDM system, this paper presents an improved FD-SAGE channel estimate algorithm. On the basis of FD-SAGE algorithm, a modified SAGE algorithm is derived through decomposing and analyzing the potential and incomplete data of SAGE algorithm. Meanwhile, the maximum likelihood algorithm is introduced in the process of refreshing data information in SAGE algorithm, and then the reliability of system is improved. The theoretical analysis and simulation results show that this algorithm can better track the channel change and acquire a faster convergence speed, just in cost of a slight system complexity. The performance is better than the traditional Least Square (LS)algorithm. Comparing with the ideal channel estimation under the maximum likelihood algorithm in signal detection, the new proposed algorithm has only a loss of 0.5 dB with the same bit error rate.
Diversity of MMSE MIMO Receivers
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...
Performance of Cross-layer Design with Multiple Outdated Estimates in Multiuser MIMO System
Directory of Open Access Journals (Sweden)
X. Yu
2014-09-01
Full Text Available By combining adaptive modulation (AM and automatic repeat request (ARQ protocol as well as user scheduling, the cross-layer design scheme of multiuser MIMO system with imperfect feedback is presented, and multiple outdated estimates method is proposed to improve the system performance. Based on this method and imperfect feedback information, the closed-form expressions of spectral efficiency (SE and packet error rate (PER of the system subject to the target PER constraint are respectively derived. With these expressions, the system performance can be effectively evaluated. To mitigate the effect of delayed feedback, the variable thresholds (VTs are also derived by means of the maximum a posteriori method, and these VTs include the conventional fixed thresholds (FTs as special cases. Simulation results show that the theoretical SE and PER are in good agreement with the corresponding simulation. The proposed CLD scheme with multiple estimates can obtain higher SE than the existing CLD scheme with single estimate, especially for large delay. Moreover, the CLD scheme with VTs outperforms that with conventional FTs.
A hybrid intelligent controller for a twin rotor MIMO system and its hardware implementation.
Juang, Jih-Gau; Liu, Wen-Kai; Lin, Ren-Wei
2011-10-01
This paper presents a fuzzy PID control scheme with a real-valued genetic algorithm (RGA) to a setpoint control problem. The objective of this paper is to control a twin rotor MIMO system (TRMS) to move quickly and accurately to the desired attitudes, both the pitch angle and the azimuth angle in a cross-coupled condition. A fuzzy compensator is applied to the PID controller. The proposed control structure includes four PID controllers with independent inputs in 2-DOF. In order to reduce total error and control energy, all parameters of the controller are obtained by a RGA with the system performance index as a fitness function. The system performance index utilized the integral of time multiplied by the square error criterion (ITSE) to build a suitable fitness function in the RGA. A new method for RGA to solve more than 10 parameters in the control scheme is investigated. For real-time control, Xilinx Spartan II SP200 FPGA (Field Programmable Gate Array) is employed to construct a hardware-in-the-loop system through writing VHDL on this FPGA.
Time-Delay Neural Network for Smart MIMO Channel Estimation in Downlink 4G-LTE-Advance System
Directory of Open Access Journals (Sweden)
Nirmalkumar S. Reshamwala
2014-05-01
Full Text Available Long-Term Evolution (LTE is the next generation of current mobile telecommunication networks. LTE has a new ﬂat radio-network architecture and signiﬁcant increase in spectrum efficiency. In this paper, main focus on throughput performance analysis of robust MIMO channel estimators for Downlink Long Term Evolution-Advance (DL LTE-A-4G system using three Artificial Neural Networks: Feed-forward neural network (FFNN, Cascade-forward neural network (CFNN and Time-Delay neural network (TDNN are adopted to train the constructed neural networks’ models separately using Back-Propagation Algorithm. The methods use the information received 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 MIMO channel matrix and try to improve throughput of LTE. The performance of the estimation methods is evaluated by simulations in Vienna LTE-A DL Link Level Simulator. Performance of the proposed channel estimator, Time-Delay neural network (TDNN is compared with traditional Least Square (LS algorithm and ANN based other estimators 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 TDNN gives better performance than other ANN based estimations methods and LS.
Cross-layer design for cooperative MIMO systems with relay selection and imperfect CSI
Institute of Scientific and Technical Information of China (English)
YU XiangBin; ZHOU TingTing; RUI Yun; YIN Xin; CHEN Ming
2013-01-01
Based on imperfect channel state information （CSI） and relay selection, a cross-layer optimization scheme is developed for cooperative MIMO system, and the corresponding system performance is investigated in Rayleigh fading channel. By the theoretical analysis and mathematical manipulation, the average spectral efficiency （SE）, packet error rate （PER） and packet loss rate （PLR） are derived. As a result, closed-form expressions of the average SE, PER and PLR are obtained, respectively. According to these, a cross-layer design （CLD） scheme subject to the average PER constraints is proposed to avoid the SE performance loss caused by the conventional instantaneous PER constraints. The scheme optimizes the adaptive thresholds by maximizing the average SE of the system, and an iteration method joint the Lagrange multiplier and Newton methods is presented to solve the above optimization problem. Simulation results verify the validity of the theoretical analysis. The results show that the proposed CLD scheme can improve the SE while target PLR is maintained. The CLD scheme under average PER constraints has higher SE than the conventional CLD scheme under instantaneous PER constraints.
Large-System Analysis of Joint User Selection and Vector Precoding for Multiuser MIMO Downlink
Takeuchi, Keigo; Kawabata, Tsutomu
2012-01-01
Joint user selection (US) and vector precoding (US-VP) is proposed for multiuser multiple-input multiple-output (MU-MIMO) downlink. The main difference between joint US-VP and conventional US is that US depends on data symbols for joint US-VP, whereas conventional US is independent of data symbols. The replica method is used to analyze the performance of joint US-VP in the large-system limit, where the numbers of transmit antennas, users, and selected users tend to infinity while their ratios are kept constant. The analysis under the assumptions of replica symmetry (RS) and 1-step replica symmetry breaking (1RSB) implies that optimal data-independent US provides nothing but the same performance as random US in the large-system limit, whereas data-independent US is capacity-achieving as only the number of users tends to infinity. It is shown that joint US-VP can provide a substantial reduction of the energy penalty in the large-system limit. Consequently, joint US-VP outperforms separate US-VP in terms of the ...
DEFF Research Database (Denmark)
Porto da Silva, Edson; Zibar, Darko
2016-01-01
Simple analytical widely linear complex-valued models for IQ-imbalance and IQ-skew effects in multicarrier transmitters are presented. To compensate for such effects, a 4×4 MIMO widely linear adaptive equalizer is proposed and experimentally validated.......Simple analytical widely linear complex-valued models for IQ-imbalance and IQ-skew effects in multicarrier transmitters are presented. To compensate for such effects, a 4×4 MIMO widely linear adaptive equalizer is proposed and experimentally validated....
基于选择性映射的MIMO-OFDM系统中PAPR减小技术%PAPR reduction for MIMO-OFDM system using selective mapping
Institute of Scientific and Technical Information of China (English)
杨娟; 颜彪; 朱一欢; 王海洋; 杨学凯
2007-01-01
针对MIMO-OFDM系统模型,在传统的独立选择性映射(SLM)方案基础上,提出一种改进的SLM方案,大大减小了辅助信息量,并着重对MIMO-OFDM系统中SLM技术采用的各种相位序列进行探讨.仿真结果表明,对于MIMO-OFDM系统中峰平功率比(PAPR),选择Golay序列、随机序列以及Shpiro-Rudin序列作为SLM的相位序列效果较好,而选择OVSF序列和Walsh-Hadamard序列效果较差.
Robust MMSE Transceiver Designs for Downlink MIMO Systems with Multicell Cooperation
Directory of Open Access Journals (Sweden)
Jialing Li
2010-01-01
Full Text Available The robust-generalized iterative approach (Robust-GIA, robust-fast iterative approach (Robust-FIA, and robust-decoder covariance optimization approach (Robust-DCOA are proposed for designing MMSE transceivers of downlink multicell multiuser MIMO systems with per-cell and per-antenna power constraints and possibly imperfect channel state information. The Robust-DCOA is the most restrictive but is always optimum, the Robust-GIA is the most general, and the Robust-FIA is the most efficient. When the Robust-DCOA is applicable and the decoder covariance matrices are full rank, the three proposed approaches are equivalent and all provide the optimum solution. Numerical results show that the proposed robust approaches outperform their non-robust counterparts in various single-cell and multicell examples with different system configurations, channel correlations, power constraints, and cooperation scenarios. Moreover, performances of the robust approaches are insensitive to estimation errors of channel statistics (correlations and path loss. With cell-cooperation, cell edge interference problems can be remedied without reducing the number of data streams by using the proposed robust approaches.
Performance Analysis of Beamforming in MU-MIMO Systems for Rayleigh Fading Channels
Hassan, Ahmad K.
2017-03-25
This paper characterizes the performance metrics of MU-MIMO systems under Rayleigh fading channels in the presence of both cochannel interference and additive noise with unknown channel state information and known correlation matrices. In the first task, we derive analytical expressions for the cumulative distribution function of the instantaneous signal-to-interference-plus-noise ratio (SINR) for any deterministic beamvectors. As a second task, exact closed-form expressions are derived for the instantaneous capacity, the upper bound on ergodic capacity, and the Gram-Schmidt orthogonalization-based ergodic capacity for similar intra-cell correlation coefficients. Finally, we present the utility of several structured-diagonalization techniques, which can achieve the tractability for the approximate solution of ergodic capacity for both similar as well as different intra-cell correlation matrices. The novelty of this paper is to formulate the received SINR in terms of indefinite quadratic forms, which allows us to use complex residue theory to characterize the system behavior. The analytical expressions obtained closely match simulation results.
Directory of Open Access Journals (Sweden)
Veselinovic Nenad
2004-01-01
Full Text Available Iterative multiuser detection in a single-carrier broadband multiple-input multiple-output (MIMO system is studied in this paper. A minimum mean squared error (MMSE low-complexity multiuser receiver is derived for space-division multiple-access (SDMA space-time trellis-coded (STTrC systems in frequency-selective fading channels. The receiver uses MMSE filtering to jointly detect several transmit antennas of the user of interest, while the interference from the undetected transmit antennas, cochannel interference (CCI, and intersymbol interference (ISI are all cancelled by the soft cancellation. The performances of two extreme receiver cases are evaluated. In the first case, only one transmit antenna of the user of interest is detected at a time and the remaining ones are cancelled by soft cancellation. In the second case, all the transmit antennas are detected jointly. The comparison of the two cases shows improvement with the latter one, both in single-user and multiuser communications and in the presence of unknown cochannel interference (UCCI. It is further shown that in the multiuser case, the proposed receivers approach the corresponding single-user bounds. The number of receive antenna elements required to achieve single-user bound is thereby equal to the number of users and not to the total number of transmit antennas.
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.
Worst-Case Energy Efficiency Maximization in a 5G Massive MIMO-NOMA System.
Chinnadurai, Sunil; Selvaprabhu, Poongundran; Jeong, Yongchae; Jiang, Xueqin; Lee, Moon Ho
2017-09-18
In this paper, we examine the robust beamforming design to tackle the energy efficiency (EE) maximization problem in a 5G massive multiple-input multiple-output (MIMO)-non-orthogonal multiple access (NOMA) downlink system with imperfect channel state information (CSI) at the base station. A novel joint user pairing and dynamic power allocation (JUPDPA) algorithm is proposed to minimize the inter user interference and also to enhance the fairness between the users. This work assumes imperfect CSI by adding uncertainties to channel matrices with worst-case model, i.e., ellipsoidal uncertainty model (EUM). A fractional non-convex optimization problem is formulated to maximize the EE subject to the transmit power constraints and the minimum rate requirement for the cell edge user. The designed problem is difficult to solve due to its nonlinear fractional objective function. We firstly employ the properties of fractional programming to transform the non-convex problem into its equivalent parametric form. Then, an efficient iterative algorithm is proposed established on the constrained concave-convex procedure (CCCP) that solves and achieves convergence to a stationary point of the above problem. Finally, Dinkelbach's algorithm is employed to determine the maximum energy efficiency. Comprehensive numerical results illustrate that the proposed scheme attains higher worst-case energy efficiency as compared with the existing NOMA schemes and the conventional orthogonal multiple access (OMA) scheme.
Directory of Open Access Journals (Sweden)
K. Vidhya
2014-05-01
Full Text Available This research study mainly focuses to develop an efficient channel estimation approach through swarm intelligence approach with lesser computational complexity. Orthogonal Frequency Division Multiplexing (OFDM is a modulation approach used to fight with the selection of frequency of the transmission channels to attain high data rate without any disturbances. OFDM principle is to gain popularity in the wireless transmission area. OFDM is united with antenna at the transmitter and receiver to amplify the variety gain and to improve the system capacity on time-variant and frequency selective channels, ensuing in a Multiple-Input Multiple-Output (MIMO pattern. Least Square (LS and Minimum Mean Square Error (MMSE approaches are the most commonly used channel estimation techniques. In LS, the estimation process is simple but the problem is that it has high mean square error. In Low SNR, the MMSE is better than that of LS, but its main problem is its high computational complexity. In order to overcome the above said problems, a novel method is proposed in this research study which combines LS and MMSE. In this study improved PSO is introduced to select the best channel. Also that this proposed approach is more efficient and also requires less time to estimate the best channel when compared with other techniques. The experimental results show the performance of the proposed channel estimation method over the existing methods.
Diversity-Multiplexing Tradeoff via Asymptotic Analysis of Large MIMO Systems
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...
Simultaneous Wireless Information and Power Transfer for MIMO Amplify-and-Forward Relay Systems
Benkhelifa, Fatma
2016-03-28
© 2015 IEEE. In this paper, we investigate two-hop Multiple- Input Multiple-Output (MIMO) Amplify-and-Forward (AF) relay communication systems with simultaneous wireless information and power transfer (SWIPT) at the multi-antenna energy harvesting relay. We derive the optimal source and relay covariance matrices to characterize the achievable region between the source-destination rate and the harvested energy at the relay, namely Rate-Energy (R-E) region. In this context, we consider the ideal scenario where the energy harvester (EH) receiver and the information decoder (ID) receiver at the relay can simultaneously decode the information and harvest the energy at the relay. This scheme provides an outer bound for the achievable R-E region since practical energy harvesting circuits are not yet able to harvest the energy and decode the information simultaneously. Then, we consider more practical schemes which are the power splitting (PS) and the time switching (TS) proposed in [1] and which separate the EH and ID transfer over the power domain and the time domain, respectively. In our study, we derive the boundary of the achievable R- E region and we show the effect of the source transmit power, the relay transmit power and the position of the relay between the source and the destination on the achievable R-E region for the ideal scenario and the two practical schemes.
MIMO Precoding in Underlay Cognitive Radio Systems with Completely Unknown Primary CSI
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...
BEP Enhancement for Semi-Femtocell MIMO Systems Employing SC-QICs and OSTBCs
Directory of Open Access Journals (Sweden)
Ardavan Rahimian
2013-01-01
Full Text Available In mobile cellular networks, it is estimated that more than 60% of voice and data services occur indoors. Therefore, cellular network operators have shown an unprecedented interest in research on femtocell systems from various aspects to extend the indoor wireless coverage for providing high-quality and high data-rate wireless multimedia services contents. In an effort for reducing the bit-error probabilities (BEPs and also increasing bit/symbol capacity of bandwidth limited error-prone wireless channels in femtocell propagation areas, this paper presents the performance of a promising candidate technology designed based on the state-of-the-art techniques. The performance of powerful space-time turbo codes (STTCs based on serial concatenation of quadratic interleaved codes (SC-QICs with the optimal and also suboptimal decoding algorithms, in conjunction with orthogonal space-time block codes (OSTBCs have been presented in this contribution for wireless multiple-input single-output (MISO, and multiple-input multiple-output (MIMO semi-femtocells.
Directory of Open Access Journals (Sweden)
Ermanna Conte
2010-01-01
Full Text Available We consider a multiuser downlink transmission from a base station with multiple antennas (MIMO to mobile terminals (users with a single antenna, using orthogonal frequency division multiplexing (OFDM. Channel conditions are reported by a feedback from users with limited rate, and the base station schedules transmissions and beamforms signals to users. We show that an important set of schedulers using a general utility function can be reduced to a scheduler maximizing the weighted sum rate of the system. For this case we then focus on scheduling methods with many users and OFDM subcarriers. Various scheduling strategies are compared in terms of achieved throughput and computational complexity and a good tradeoff is identified in greedy and semiorthogonal user selection algorithms. In the greedy selection algorithm, users are selected one by one as long as the throughput increases, while in the semiorthogonal approach users are selected based on the channel correlation. An extension of these approaches from a flat-fading channel to OFDM is considered and simplifications that may be useful for a large number of subcarriers are presented. Results are reported for a typical cellular transmission of the long-term evolution (LTE of 3GPP.
Cui, Ying; Lau, Vincent K N
2010-01-01
In this paper, we propose a two-timescale delay-optimal dynamic clustering and power allocation design for downlink network MIMO systems. The dynamic clustering control is adaptive to the global queue state information (GQSI) only and computed at the base station controller (BSC) over a longer time scale. On the other hand, the power allocations of all the BSs in one cluster are adaptive to both intra-cluster channel state information (CCSI) and intra-cluster queue state information (CQSI), and computed at the cluster manager (CM) over a shorter time scale. We show that the two-timescale delay-optimal control can be formulated as an infinite-horizon average cost Constrained Partially Observed Markov Decision Process (CPOMDP). By exploiting the special problem structure, we shall derive an equivalent Bellman equation in terms of Pattern Selection Q-factor to solve the CPOMDP. To address the distributive requirement and the issue of exponential memory requirement and computational complexity, we approximate the...
Two-Way Training Design for Discriminatory Channel Estimation in Wireless MIMO Systems
Huang, Chao-Wei
2011-01-01
This work examines the use of two-way training in multiple-input multiple-output (MIMO) wireless systems to discriminate the channel estimation performances between a legitimate receiver (LR) and an unauthorized receiver (UR). This thesis extends upon the previously proposed discriminatory channel estimation (DCE) scheme that allows only the transmitter to send training signals. The goal of DCE is to minimize the channel estimation error at LR while requiring the channel estimation error at UR to remain beyond a certain level. If the training signal is sent only by the transmitter, the performance discrimination between LR and UR will be limited since the training signals help both receivers perform estimates of their downlink channels. In this work, we consider instead the two-way training methodology that allows both the transmitter and LR to send training signals. In this case, the training signal sent by LR helps the transmitter obtain knowledge of the transmitter-to-LR channel, but does not help UR estim...
Closed-Form Approximation of MIMO Capacity
Akhtman, Jos; Hanzo, Lajos
2009-01-01
A closed-form expression is provided for the calculation of the minimum SNR required to achieve a target data-rate using a generic MIMO-aided $M$-QAM transceiver. The computationally efficient technique proposed facilitates the convenient characterization of MIMO-assisted wireless systems.
MIMO over ESPAR with 16-QAM Modulation
DEFF Research Database (Denmark)
Han, Bo; Barousis, V.I.; Papadias, C.B.;
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 sing...
BER Analysis Of IEEE802.11n MIMO System Using MMSE And ZF Detectors
Directory of Open Access Journals (Sweden)
Ye Lwin Oo
2015-06-01
Full Text Available Abstract With the increasing demand of higher data rate for telecommunication the IEEE802.11n standard was constituted in 2009. The most important character of the standard is MIMO-OFDM which not only improves the throughput but also the spectrum efficiency and channel capacity. And in wireless communication the role of MIMO detectors plays an important part to remove inter-symbol interference ISI caused by multipath fading channel. In this paper the BER performance of IEEE 802.11n for 3x2 4x2 and 4x3 antennas are compared using MMSE and ZF detectors in Matlab Simulink.
A HOS-based Blind Signal Extraction Method for Chaotic MIMO Systems
Institute of Scientific and Technical Information of China (English)
GONG Yun-rui; HE Di; HE Chen; JIANG Ling-ge
2008-01-01
A novel method to extract multiple input and multiple output (MIMO) chaotic signals was pro-posed using the blind neural algorithm after transmitting in nonideal channel. The MIMO scheme with different chaotic signal generators was presented. In order to separate the chaotic source signals only by using the sensor signals at receivers, a blind neural extraction algorithm based on higher-order statistic (HOS) technique was used to recover the primary chaotic signals. Simulation results show that the proposed approach has good performance in separating the primary chaotic signals even under nonideal channel.
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.
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.
Properties of blocked linear systems.
Chen, Weitian; Anderson, Brian D O; Deistler, Manfred; Filler, Alexander
2012-10-01
This paper presents a systematic study on the properties of blocked linear systems that have resulted from blocking discrete-time linear time invariant systems. The main idea is to explore the relationship between the blocked and the unblocked systems. Existing results are reviewed and a number of important new results are derived. Focus is given particularly on the zero properties of the blocked system as no such study has been found in the literature.
Yang, Liang
2013-06-01
This paper considers a multiuser spectrum sharing (SS) multiple-input multiple-output (MIMO) system with zero-forcing (ZF) operating in a Rayleigh fading environment. We provide an asymptotic sum-rate analysis to investigate the effects of different parameters on the multiuser diversity gain. For a ZF SS spatial multiplexing system with scheduling, the asymptotic sum-rate scales like Nt log2(Q(Nt Np√K - 1)/N t), where Np denotes the number of antennas of primary receiver, Q is the interference temperature, and K represents the number of secondary transmitters. © 2013 IEEE.
Multiuser MIMO Transmitter Optimization for Inter-Cell Interference Mitigation
Huh, Hoon; Caire, Giuseppe
2009-01-01
The optimization of the transmitter precoder (steering vectors and power allocation) for a MIMO Broadcast Channel (MIMO-BC) subject to general linear constraints is considered. These include various types of system constraints such as sum power, per-antenna or per-group-of-antennas power constraints, and "forbidden interference direction" constraints. We consider the transmitter optimization problem under either the optimal dirty-paper coding and the simple suboptimal linear zero-forcing beamforming strategies. In both cases, we provide numerically efficient algorithms that solve the problem in the most general form. As an application, we consider a multi-cell scenario with partial cell cooperation, where each cell optimizes its precoder by taking into account interference constraints on specific users in adjacent cells. The effectiveness of the proposed method is evaluated in a simple system setting with two adjacent cells, under different fairness criteria that emphasize the role of users near the cell "bou...
分布式MIMO系统的复合信道容量分析%Capacity analysis of compound channel for distributed MIMO system
Institute of Scientific and Technical Information of China (English)
刘伟; 汪清
2013-01-01
Distributed MIMO system combines the characteristics of MIMO channel and distributed antenna system, which is believed a very promising technology in the future of 4G, because of its large capacity, large coverage and less power loss from shadow and distance. A compound channel model considering path loss, lognormal shadow fading and small scale fading for distributed MIMO system model is adopted, the capacity of which is analyzed. Besides channel capacity between distributed MIMO system and centralized MIMO system is compared by Monte Carlo simulations. At the same time, the impact of spatial fading correlation and path loss on the capacity is also investigated. The simulation results prove that distributed MIMO system can effectually reduce the impact of small scale fading, and achieve a better channel capacity.%分布式MIMO系统结合了MIMO技术和分布式天线系统两者的特点,具有高容量、大覆盖范围、低损耗的优势,在未来4G通信中具有很好的应用前景.基于包含了路径损耗、阴影衰落和相关小尺度衰落的分布式MIMO信道模型,通过Monte Carlo仿真比较分析了分布式MIMO系统和集中式MIMO系统的信道容量,研究了空间相关性和路径损耗对信道容量的影响.仿真实验结果表明,分布式MIMO系统能有效降低小尺度衰落相关性的影响,可以获得更好的平均信道容量.
MIMO系统的信号检测算法%Research on Signal Detection Algorithms For MIMO Communication Systems
Institute of Scientific and Technical Information of China (English)
田根林; 李华
2016-01-01
In the high-speed broadband wireless communication systems, Multi-input and multi-output(MIMO) technology can improve transmission rate and spectrum efficiencies without any increase of system bandwidth and transmitting power. Thus, the signal detection for MIMO systems is challenging because of the channel noise and multipath fading, and has become the biggest block of development. In this paper, most attention is concentrated on the signal detection algorithms for MIMO Communication Systems, through the comparision with the existent algorithms and the simulations, we can conclude that the signal detection algorithm based on sphere decoding has a better detection effect. Due to the introduction of the interference cancellation and the ordering rule, the algorithm optimality of ZF-OSIC and MMSE-OSIC is both improved effectively.%在高速宽带无线通信系统中,MIMO技术能够在不增加系统带宽和发射功率的情况下,有效提高系统传输速率和频谱效率。然而,由于不同发射天线发出的信号的相互干扰以及无线通信系统的多径效应,使得MIMO系统的信号检测面临巨大挑战,严重阻碍了MIMO技术的广泛应用。因此本文主要针对MIMO系统的信号检测算法进行研究,通过算法比较和仿真验证可以得出,基于球形译码的信号检测(SD)算法具有更优的检测结果。由于引入干扰抵消和排序机制,ZF-OSIC和MMSE-OSIC算法在性能方面得到了提升。
Directory of Open Access Journals (Sweden)
Claude D'Amours
2011-01-01
Full Text Available We analytically derive the upper bound for the bit error rate (BER performance of a single user multiple input multiple output code division multiple access (MIMO-CDMA system employing parity-bit-selected spreading in slowly varying, flat Rayleigh fading. The analysis is done for spatially uncorrelated links. The analysis presented demonstrates that parity-bit-selected spreading provides an asymptotic gain of 10log(Nt dB over conventional MIMO-CDMA when the receiver has perfect channel estimates. This analytical result concurs with previous works where the (BER is determined by simulation methods and provides insight into why the different techniques provide improvement over conventional MIMO-CDMA systems.
Impact of MIMO Co-Channel Interference
DEFF Research Database (Denmark)
Rahman, Muhammad Imadur; De Carvalho, Elisabeth; Prasad, Ramjee
2007-01-01
to cellular interference of some specific Multiple Input Multiple Output (MIMO) schemes on the same and other MIMO schemes. The goal is to study the impact of interference from MIMO schemes at a user located in the cell edge. Semi-Analytical evaluations of Signal to Interference and Noise Ratio (SINR) is done...... to find out the SINR statistics of different combinations of desired and interfering links. We have studied linear combining receivers for all the link combinations. Based on the current analysis, it is found that Space-Time Block Code (STBC) is a severe interferer compared to others, and specific...
三维粗糙面上的MIMO信道模型%Model of MIMO System above a Three-Dimensional Random Rough Surface
Institute of Scientific and Technical Information of China (English)
李维; 金亚秋
2011-01-01
多天线构成的多输入多输出MIMO（Multiple-Input Multiple-Output）信道是B3G/4G系统的关键技术之一。文章建立下垫三维粗糙面的MIMO信道模型,用基尔霍夫（KA,Kirchhoff approximation）近似随机粗糙面散射的数值计算方法研究下垫粗糙面产生的随机多路径传输对MIMO信道矩阵的影响,并数值地讨论接收、发射天线阵列位置以及下垫粗糙面几何参数对MIMO系统信道容量的影响。结果表明,双站距离大、天线高度低时,下垫随机粗糙面对MIMO信道容量的影响显著。当天线阵元%Multiple input-multiple output（MIMO） system has becomes one of key techniques for developing B3G/4G systems.In this paper,a model of the MIMO system above a 3-D random rough surface is presented.Using Monte Carlo method,underlying random rough surface is realized.The Kirchhoff approximation（KA） is applied to numerical calculation of rough surface scattering for implementing multi-path propagation and the channel transfer matrix of MIMO system.It numerically shows the dependence of the MIMO system capacity upon physical parameters of the MIMO antenna arrays and underlying surface.It is found that when the inter-element separation of the antenna array is small,the underlying rough surface can significantly increase the MIMO capacity.However,when the separation is large,the MIMO capacity above the rough surface becomes lower.
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
Institute of Scientific and Technical Information of China (English)
Zhu Yanping; Song Yaoliang; Chen Jinli; Zhao Delin
2012-01-01
Compressed Sensing (CS) theory is a great breakthrough of the traditional Nyquist sampling theory.It can accomplish compressive sampling and signal recovery based on the sparsity of interested signal,the randomness of measurement matrix and nonlinear optimization method of signal recovery.Firstly,the CS principle is reviewed.Then the ambiguity function of Multiple-Input Multiple-Output (MIMO) radar is deduced.After that,combined with CS theory,the ambiguity function of MIMO radar is analyzed and simulated in detail.At last,the resolutions of coherent and non-coherent MIMO radars on the CS theory are discussed.Simulation results show that the coherent MIMO radar has better resolution performance than the non-coherent.But the coherent ambiguity function has higher side lobes,which caused a deterioration in radar target detection performances.The stochastic embattling method of sparse array based on minimizing the statistical coherence of sensing matrix is proposed.And simulation results show that it could effectively suppress side lobes of the ambiguity function and improve the capability of weak target detection.
Three-dimensional model of hydro acoustic channel for research MIMO systems
Fedosov, V. P.; Lomakina, A. V.; Legin, A. A.; Voronin, V. V.
2017-05-01
Currently, wireless hydroacoustic modems are actively being developed, which are used to provide efficient data transmission in the hydroacoustic channel. Such kind of developments are relevant for today, as they are used in various fields of science and fields of activity. An example is the connection with underwater vehicles for scientific, research, search and rescue purposes. Development of this kind of communication systems (modems) is a difficult task, as signal propagation is affected by various factors. As a result, the transfer characteristic changes with time, thereby imposing restrictions on the acoustic communication channel. In this regard, the researchers began the task of further study sonar environment and get a detailed mathematical description of the underwater channel. For this, a huge number of field tests were conducted, aimed at studying the underwater acoustic environment. However, the results of the research are always limited by the conditions in which the test took place. Therefore, it is not always possible to apply these results to the required conditions. All of the above features do not allow you to create some kind of a commonly accepted model for the acoustic channel, as studies based on experiments, collected in localized environments without generalizations. This paper presents, the three-dimensional model of the sonar channel for MIMO systems in the coastal zone, based on the acoustic signal propagation characteristics in the presence of multiple paths, the influence of the Doppler effect (as a result of mobile and / or base station traffic), in terms of signal attenuation, receiver characteristics influence and Transmitting antenna, etc.
Institute of Scientific and Technical Information of China (English)
Chen Jing; Zhu Qi
2008-01-01
In this paper, the design of signal constellations parameters is studied for Differential Unitary Space-Time Modulation (DUSTM) based on the design criterion of maximizing the diversity product. Farther, noninteger searching method for the signal constellation parameters design is proposed in order to get better codes. Experimental results show that under the different Doppler spread and data transmission rate, the proposed design performs better than the previous design using integer parameters in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing(MIMO-OFDM) system over frequency-selective fading channels.
Deng, Lei; Pang, Xiaodan; Zhao, Ying; Othman, M B; Jensen, Jesper Bevensee; Zibar, Darko; Yu, Xianbin; Liu, Deming; Monroy, Idelfonso Tafur
2012-02-13
We propose a spectral efficient radio over wavelength division multiplexed passive optical network (WDM-PON) system by combining optical polarization division multiplexing (PDM) and wireless multiple input multiple output (MIMO) spatial multiplexing techniques. In our experiment, a training-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 (fiber followed by 3 m and 1 m air distances, respectively.
Time-Delay Neural Network for Smart MIMO Channel Estimation in Downlink 4G-LTE-Advance System
Nirmalkumar S. Reshamwala; Pooja S. Suratia; Satish K. Shah
2014-01-01
Long-Term Evolution (LTE) is the next generation of current mobile telecommunication networks. LTE has a new ﬂat radio-network architecture and signiﬁcant increase in spectrum efficiency. In this paper, main focus on throughput performance analysis of robust MIMO channel estimators for Downlink Long Term Evolution-Advance (DL LTE-A)-4G system using three Artificial Neural Networks: Feed-forward neural network (FFNN), Cascade-forward neural network (CFNN) and Time-Delay neural network (TDNN) a...
大规模MIMO系统中动态导频分配%Dynamic Pilot Allocation in Massive MIMO System
Institute of Scientific and Technical Information of China (English)
方昕; 张建锋; 曹海燕; 刘超; 潘鹏
2016-01-01
针对大规模多输入多输出(MIMO)系统中存在的导频污染问题，该文提出一种动态导频分配方案。所提方案利用目标小区与干扰小区用户之间的信号干扰强度差将干扰小区分为U in和U out两类，并对U in中的用户进行最优导频分配，U out中的用户进行随机导频分配来提升系统的平均下行可达和速率。同时，在存在额外正交导频组的情况下对所提方案做了进一步优化。仿真结果表明，所提的动态导频分配方案能够有效地提升大规模MIMO系统的性能。%A dynamic pilot allocation scheme is proposed in case of the pilot contamination existing in massive MIMO system. Based on the signal to interference difference between the aim cell user and the interference cell user, the interference cell is divided intoinU andoutU. Specifically, in order to improve the average downlink achievable sum rates, the users in theinU are operated with the optimal pilot allocation, and the users in the outU are operated with the random pilot allocation. Simultaneously, the proposed pilot allocation scheme is further optimized with an extral set of orthogonal pilots. Simulation results show that the proposed dynamic pilot allocation scheme can enhance the downlink performance of the massive MIMO system effectively.
Feedback systems for linear colliders
Hendrickson, L; Himel, Thomas M; Minty, Michiko G; Phinney, N; Raimondi, Pantaleo; Raubenheimer, T O; Shoaee, H; Tenenbaum, P G
1999-01-01
Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an intregal part of the design. Feedback requiremetns for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at hi...
Iterative solution of linear systems
Freund, Roland W.; Golub, Gene H.; Nachtigal, Noel M.
1992-01-01
Recent advances in the field of iterative methods for solving large linear systems are reviewed. The main focus is on developments in the area of conjugate gradient-type algorithms and Krylov subspace methods for nonHermitian matrices.
Analytical Expression for the MIMO Channel Capacity
Institute of Scientific and Technical Information of China (English)
ZHAO Yifei; ZHAO Ming; XIAO Limin; WANG Jing
2006-01-01
This paper presents analytical expressions for the multiple-input multiple-output (MIMO) channel capacity in frequency-flat Rayleigh fading environments. An exact analytical expression is given for the ergodic capacity for single-input multiple-output (SIMO) channels. The analysis shows that the SIMO channel capacity can be approximated by a Gaussian random variable and that the MIMO channel capacity can be approximated as the sum of multiple SIMO capacities. The SIMO channel results are used to derive approximate closed-form expressions for the MIMO channel ergodic capacity and the complementary cumulative distribution function (CCDF) of the MIMO channel capacity (outage capacity). Simulations show that these theoretical results are good approximations for MIMO systems with an arbitrary number of transmit or receive antennas. Moreover, these analytical expressions are relatively simple which makes them very useful for practical computations.
Mitigation of MIMO Co-Channel Interference using robust interference cancellation receiver
DEFF Research Database (Denmark)
Rahman, Muhammad Imadur; De Carvalho, Elisabeth; Prasad, Ramjee
2007-01-01
(STBC) link may become equivalent to an interfering Spatial Multiplexing (SM) link. Using this knowledge and understanding, we propose an interference cancellation receiver robust to different types of MIMO interferers at cell edge for the Downlink (DL) of cellular systems. The receiver systematically......) statistics and Bit Error Rate (BER) performance in cellular Orthogonal Frequency Division Multiple Access (OFDMA) systems. We have found that the proposed multiple-symbol linear interference cancellation receiver performs satisfactorily when any kind of single 'logical' stream MIMO scheme is present...
Chen, Zhenfeng; Ge, Shuzhi Sam; Zhang, Yun; Li, Yanan
2014-11-01
This paper presents adaptive neural tracking control for a class of uncertain multiinput-multioutput (MIMO) nonlinear systems in block-triangular form. All subsystems within these MIMO nonlinear systems are of completely nonaffine pure-feedback form and allowed to have different orders. To deal with the nonaffine appearance of the control variables, the mean value theorem is employed to transform the systems into a block-triangular strict-feedback form with control coefficients being couplings among various inputs and outputs. A systematic procedure is proposed for the design of a new singularity-free adaptive neural tracking control strategy. Such a design procedure can remove the couplings among subsystems and hence avoids the possible circular control construction problem. As a consequence, all the signals in the closed-loop system are guaranteed to be semiglobally uniformly ultimately bounded. Moreover, the outputs of the systems are ensured to converge to a small neighborhood of the desired trajectories. Simulation studies verify the theoretical findings revealed in this paper.
MIMO OFDM短波无线通信的频率同步技术研究%Frequency Synchronization for MIMO OFDM HF Wireless Communication Systems
Institute of Scientific and Technical Information of China (English)
缪刚; 周志中
2007-01-01
多输入多输出(MIMO)技术是最近几年发展起来的无线通信技术.目前利用MIMO技术提高短波通信的传输速率和可靠性的研究已经开展.论文着重研究了MIMO OFDM短波无线通信的频率同步技术,利用频域正交的训练序列完成了系统各个发射/接收天线对之间频偏不同时的载波频偏估计.
Compressive Sensing for MIMO Radar
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.
Institute of Scientific and Technical Information of China (English)
徐福永; 李光球
2006-01-01
研究了多址干扰下,MIMO WCDMA系统发射端采用空时分组码和卷积码、接收端采用最大比合并天线分集和软判决译码方案的误码性能.使用Q(x)的另一种数学表达式和信干噪比的矩生成函数,推导了Nakagami-m衰落信道上存在多址干扰以及发射端发射不等功率下,卷积编码系统的成对差错概率和误码性能联合限.讨论了在各种编码方案下空间路径分集接收机的误码性能.数值计算结果表明组合空间分集和卷积编码能显著改善MIMO WCDMA系统的误码性能.分析结果适用于MIMO WCDMA系统的上下行链路.
基于MIMO-OFDM技术的对流层散射通信系统研究%Tropospheric Scatter Communication System Based on MIMO-OFDM Technology
Institute of Scientific and Technical Information of China (English)
谢红; 谭泽富
2010-01-01
对流层散射通信是一种典型的随参信道,多径衰落十分突出,所以要实现高速大容量散射通信是非常困难的.为了抵抗由于多径衰落所带来的散射通信性能恶化,提出了基于MIMO-OFDM结构的的新一代对流层散射通信系统框架.通过分析散射信道中的MIMO-OFDM结构,讨论MIMO-OFDM技术应用的主要问题,发现运用该技术可以有效提高散射通信的可靠度,克服高速数据在散射信道下的多径衰落,实现散射的大容量、远距离通信.
Directory of Open Access Journals (Sweden)
Lin Sheng-Chou
2011-01-01
Full Text Available Abstract This article presents the performance analysis of multiple-input/multiple-output (MIMO systems with quadrature amplitude modulation (QAM transmission in the presence of cochannel interference (CCI in nonfading and flat Rayleigh fading environments. The use of optimum transmission (OT and maximum ratio transmission (MRT is considered and compared. In addition to determining precise results for the performance of QAM in the presence of CCI, it is our another aim in this article to examine the validity of the Gaussian interference model in the MRT-based systems. Nyquist pulse shaping and the effects of cross-channel intersymbol interference produced by CCI due to random symbol of the interfering signals are considered in the precise interference model. The error probability for each fading channel is estimated fast and accurately using Gauss quadrature rules which can approximate the probability density function (pdf of the output residual interference. The results of this article indicate that Gaussian interference model may overestimate the effects of interference, particularly, for high-order MRT-based MIMO systems over fading channels. In addition, OT cannot always outperform MRT due to the significant noise enhancement when OT intends to cancel CCI, depending on the combination of the antennas at the transmitter and the receiver, number of interference and the statistical characteristics of the channel.
Zhu, Yi-Jun; Liang, Wang-Feng; Wang, Chao; Wang, Wen-Ya
2017-01-01
In this paper, space-collaborative constellations (SCCs) for indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems are considered. Compared with traditional VLC MIMO techniques, such as repetition coding (RC), spatial modulation (SM) and spatial multiplexing (SMP), SCC achieves the minimum average optical power for a fixed minimum Euclidean distance. We have presented a unified SCC structure for 2×2 MIMO VLC systems and extended it to larger MIMO VLC systems with more transceivers. Specifically for 2×2 MIMO VLC, a fast decoding algorithm is developed with decoding complexity almost linear in terms of the square root of the cardinality of SCC, and the expressions of symbol error rate of SCC are presented. In addition, bit mappings similar to Gray mapping are proposed for SCC. Computer simulations are performed to verify the fast decoding algorithm and the performance of SCC, and the results demonstrate that the performance of SCC is better than those of RC, SM and SMP for indoor channels in general.
Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik
2008-07-01
Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.
PAR-Aware Large-Scale Multi-User MIMO-OFDM Downlink
Studer, Christoph
2012-01-01
We investigate an orthogonal frequency-division multiplexing (OFDM)-based downlink transmission scheme for large-scale multi-user (MU) multiple-input multiple-output (MIMO) wireless systems. The use of OFDM causes a high peak-to-average (power) ratio (PAR), which necessitates expensive and power-inefficient radio-frequency (RF) components at the base station. In this paper, we present a novel downlink transmission scheme, which exploits the massive degrees-of-freedom available in large-scale MU-MIMO-OFDM systems to achieve low PAR. Specifically, we propose to jointly perform MU precoding, OFDM modulation, and PAR reduction by solving a convex optimization problem. We develop a corresponding fast iterative truncation algorithm (FITRA) and show numerical results to demonstrate tremendous PAR-reduction capabilities. The significantly reduced linearity requirements eventually enable the use of low-cost RF components for the large-scale MU-MIMO-OFDM downlink.
Hu, Anzhong; Lv, Tiejun; Gao, Hui; Zhang, Zhang; Yang, Shaoshi
2014-10-01
In this paper, an approach of estimating signal parameters via rotational invariance technique (ESPRIT) is proposed for two-dimensional (2-D) localization of incoherently distributed (ID) sources in large-scale/massive multiple-input multiple-output (MIMO) systems. The traditional ESPRIT-based methods are valid only for one-dimensional (1-D) localization of the ID sources. By contrast, in the proposed approach the signal subspace is constructed for estimating the nominal azimuth and elevation direction-of-arrivals and the angular spreads. The proposed estimator enjoys closed-form expressions and hence it bypasses the searching over the entire feasible field. Therefore, it imposes significantly lower computational complexity than the conventional 2-D estimation approaches. Our analysis shows that the estimation performance of the proposed approach improves when the large-scale/massive MIMO systems are employed. The approximate Cram\\'{e}r-Rao bound of the proposed estimator for the 2-D localization is also derived. Numerical results demonstrate that albeit the proposed estimation method is comparable with the traditional 2-D estimators in terms of performance, it benefits from a remarkably lower computational complexity.
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.
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.
Analysis of Laser & Detector Placement in MIMO Multimode Optical Fiber Systems
Appaiah, Kumar; Vishwanath, Sriram; Bank, Seth R
2011-01-01
Multimode fibers (MMFs) offer a cost-effective connection solution for small and medium length networks. However, data rates through multimode fibers are traditionally limited by modal dispersion. Signal processing and Multiple-Input Multiple-Output (MIMO) have been shown to be effective at combating these limitations, but device design for the specific purpose of MIMO in MMFs is still an open issue. This paper utilizes a statistical field propagation model for MMFs to aid the analysis and designs of MMF laser and detector arrays, and aims to improve data rates of the fiber. Simulations reveal that optimal device designs could possess 2-3 times the data carrying capacity of suboptimal ones.
Novel Design of Linear Full-duplex MIMO Radios%一种线性化的全双工MIMO收发器设计
Institute of Scientific and Technical Information of China (English)
张志亮; 沈莹; 邵士海; 潘文生; 唐友喜
2016-01-01
针对全双工MIMO收发器发射通道非线性以及接收通道存在强烈自干扰的问题，该文提出一种使发射通道线性化并通过射频多抽头重建与数字重建消除自干扰的具有较低硬件成本与软件复杂度的设计方案：(1)基于改进的串扰消除和数字预失真(CTC-DPD)算法并复用反馈通道进行去耦合和数字预失真使发射通道线性化、等增益；(2)在接收通道加入可调衰减器并用多维梯度下降法基于接收的残留自干扰功率最小原则调整抽头参数；(3)基于频域信道估计进行数字自干扰重建。实现的20 MHz带宽LTE全双工2´2 MIMO通信样机，发射通道经过线性化后带内更平坦，而带外噪声抑制了约30 dB。射频和数字消除一轮调整共耗时约0.17 ms，总消除能力约75 dB。16QAM映射时全双工双向数据速率总和220 Mbps，相对单向时的110 Mbps实现了频谱效率的翻倍。通信样机证明了该方案的可行性。%Considering the issues of nonlinearity and self-interference in transmitting and receiving channels of a full-duplex MIMO radio respectively, a novel low hardware cost and low software complexity design scheme with transmitting channels linearization and self-interference cancellation by multi-tap RF cancellers and digital cancellers is proposed, where (1) An improved Cross-Talk Cancelling-Digital Pre-Distorter (CTC-DPD) algorithm and common feedback are used for decoupling and digital pre-distortion to make transmitting channels gain linearly and equally; (2) By introducing adjustable attenuators in receiving channels, multi-tap cancellers use received data along with minimum residual self-interference power criterion based multidimensional gradient descent method to search the multi-tap setting;(3) Digital self-interference is reconstructed for cancellation based on channel estimation in frequency domain. In the prototype of 20 MHz bandwidth LTE full-duplex 2×2 MIMO radio
Kavitha, Veeraruna; Sharma, Vinod
2005-01-01
Semi blind/blind equalizers are believed to work unsatisfactorily in fading MIMO channels compared to training based methods, due to slow convergence or high computational complexity. We revisit this issue. Defining a 'composite' channel for each equalizer, we compare the three algorithms based on the capacity of this channel. We show that, in a Rician (with line of sight, LOS) environment, semi blind/blind algorithms outperform training equalizers, but in Rayleigh channels, it is better to u...
Window observers for linear systems
Directory of Open Access Journals (Sweden)
Utkin Vadim
2000-01-01
Full Text Available Given a linear system x ˙ = A x + B u with output y = C x and a window function ω ( t , i.e., ∀ t , ω ( t ∈ {0,1 }, and assuming that the window function is Lebesgue measurable, we refer to the following observer, x ˆ = A x + B u + ω ( t L C ( x − x ˆ as a window observer. The stability issue is treated in this paper. It is proven that for linear time-invariant systems, the window observer can be stabilized by an appropriate design under a very mild condition on the window functions, albeit for linear time-varying system, some regularity of the window functions is required to achieve observer designs with the asymptotic stability. The corresponding design methods are developed. An example is included to illustrate the possible applications
Directory of Open Access Journals (Sweden)
Ngoc Phuc Le
2014-01-01
Full Text Available The use of per-subcarrier antenna subset selection in OFDM wireless systems offers higher system capacity and/or improved link reliability. However, the implementation of the conventional per-subcarrier selection scheme may result in significant fluctuations of the average power and peak power across antennas, which affects the potential benefits of the system. In this paper, power efficiency of high-power amplifiers and energy efficiency in per-subcarrier antenna selection MIMO-OFDM systems are investigated. To deliver the maximum overall power efficiency, we propose a two-step strategy for data-subcarrier allocation. This strategy consists of an equal allocation of data subcarriers based on linear optimization and peak-power reduction via cross-antenna permutations. For analysis, we derive the CCDF (complementary cumulative distribution function of the power efficiency as well as the analytical expressions of the average power efficiency. It is proved from the power-efficiency perspective that the proposed allocation scheme outperforms the conventional scheme. We also show that the improvement in the power efficiency translates into an improved capacity and, in turn, increases energy efficiency of the proposed system. Simulation results are provided to validate our analyses.
Preconditioned quantum linear system algorithm.
Clader, B D; Jacobs, B C; Sprouse, C R
2013-06-21
We describe a quantum algorithm that generalizes the quantum linear system algorithm [Harrow et al., Phys. Rev. Lett. 103, 150502 (2009)] to arbitrary problem specifications. We develop a state preparation routine that can initialize generic states, show how simple ancilla measurements can be used to calculate many quantities of interest, and integrate a quantum-compatible preconditioner that greatly expands the number of problems that can achieve exponential speedup over classical linear systems solvers. To demonstrate the algorithm's applicability, we show how it can be used to compute the electromagnetic scattering cross section of an arbitrary target exponentially faster than the best classical algorithm.
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...
Belief Propagation based MIMO Detection Operating on Quantized Channel Output
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...