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 ...
A Highly Parallelized MIMO Detector for Vector-Based Reconfigurable Architectures
Zhang, Chenxin; Liu, Liang; Wang, Yian; Zhu, Meifang; Edfors, Ove; Öwall, Viktor
2013-01-01
This paper presents a highly parallelized MIMO signal detection algorithm targeting vector-based reconfigurable architectures. The detector achieves high data-level parallelism and near-ML performance by adopting a vector-architecture-friendly technique - parallel node perturbation. To further reduce the computational complexity, imbalanced node and successive partial node expansion schemes in conjunction with sorted QR decomposition are applied. The effectiveness of the proposed algorithm is...
Vector perturbations of galaxy number counts
Durrer, Ruth; Tansella, Vittorio
2016-07-01
We derive the contribution to relativistic galaxy number count fluctuations from vector and tensor perturbations within linear perturbation theory. Our result is consistent with the the relativistic corrections to number counts due to scalar perturbation, where the Bardeen potentials are replaced with line-of-sight projection of vector and tensor quantities. Since vector and tensor perturbations do not lead to density fluctuations the standard density term in the number counts is absent. We apply our results to vector perturbations which are induced from scalar perturbations at second order and give numerical estimates of their contributions to the power spectrum of relativistic galaxy number counts.
Vector perturbations of galaxy number counts
Durrer, Ruth
2016-01-01
We derive the contribution to relativistic galaxy number count fluctuations from vector and tensor perturbations within linear perturbation theory. Our result is consistent with the the relativistic corrections to number counts due to scalar perturbation, where the Bardeen potentials are replaced with line-of-sight projection of vector and tensor quantities. Since vector and tensor perturbations do not lead to density fluctuations the standard density term in the number counts is absent. We apply our results to vector perturbations which are induced from scalar perturbations at second order and give numerical estimates of their contributions to the power spectrum of relativistic galaxy number counts.
Perturbations of ultralight vector field dark matter
Cembranos, J. A. R.; Maroto, A. L.; Núñez Jareño, S. J.
2017-02-01
We study the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent vector fields. Very much as for scalar field dark matter, we find two different regimes in the evolution: for modes with {k}^2≪ Hma, we have a particle-like behaviour indistinguishable from cold dark matter, whereas for modes with {k}^2≫ Hma, we get a wave-like behaviour in which the sound speed is non-vanishing and of order c s 2 ≃ k 2/ m 2 a 2. This implies that, also in these models, structure formation could be suppressed on small scales. However, unlike the scalar case, the fact that the background evolution contains a non-vanishing homogeneous vector field implies that, in general, the evolution of the three kinds of perturbations (scalar, vector and tensor) can no longer be decoupled at the linear level. More specifically, in the particle regime, the three types of perturbations are actually decoupled, whereas in the wave regime, the three vector field perturbations generate one scalar-tensor and two vector-tensor perturbations in the metric. Also in the wave regime, we find that a non-vanishing anisotropic stress is present in the perturbed energy-momentum tensor giving rise to a gravitational slip of order ( Φ - Ψ)/ Φ ˜ c s 2 . Moreover in this regime the amplitude of the tensor to scalar ratio of the scalar-tensor modes is also h/ Φ ˜ c s 2 . This implies that small-scale density perturbations are necessarily associated to the presence of gravity waves in this model. We compare their spectrum with the sensitivity of present and future gravity waves detectors.
Vector Meson Masses in Chiral Perturbation Theory
Bijnens, J; Talavera, P
1997-01-01
We discuss the vector meson masses within the context of Chiral Perturbation Theory performing an expansion in terms of the momenta, quark masses and 1/Nc. We extend the previous analysis to include isospin breaking effects and also include up to order p^4. We discuss vector meson chiral perturbation theory in some detail and present a derivation from a relativistic lagrangian. The unknown coefficients are estimated in various ways. We also discuss the relevance of electromagnetic corrections and the implications of the present calculation for the determination of quark masses.
Perturbations of ultralight vector field dark matter
Cembranos, J A R; Jareño, S J Núñez
2016-01-01
We study the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent vector fields. Very much as for scalar field dark matter, we find two different regimes in the evolution: for modes with $k^2\\ll {\\cal H}ma$, we have a particle-like behaviour indistinguishable from cold dark matter, whereas for modes with $k^2\\gg {\\cal H}ma$, we get a wave-like behaviour in which the sound speed is non-vanishing and of order $c_s^2\\simeq k^2/m^2a^2$. This implies that, also in these models, structure formation could be suppressed on small scales. However, unlike the scalar case, the fact that the background evolution contains a non-vanishing homogeneous vector field implies that, in general, the evolution of the three kinds of perturbations (scalar, vector and tensor) can no longer be decoupled at the linear level. More specifically, in the particle regime, the three types of perturbations are actually decoupled, whereas in the wave regime, the three vector field perturbations generate o...
Cross-Layer Optimization of MIMO-Based Mesh Networks with Gaussian Vector Broadcast Channels
Liu, Jia
2007-01-01
MIMO technology is one of the most significant advances in the past decade to increase channel capacity and has a great potential to improve network capacity for mesh networks. In a MIMO-based mesh network, the links outgoing from each node sharing the common communication spectrum can be modeled as a Gaussian vector broadcast channel. Recently, researchers showed that ``dirty paper coding'' (DPC) is the optimal transmission strategy for Gaussian vector broadcast channels. So far, there has been little study on how this fundamental result will impact the cross-layer design for MIMO-based mesh networks. To fill this gap, we consider the problem of jointly optimizing DPC power allocation in the link layer at each node and multihop/multipath routing in a MIMO-based mesh networks. It turns out that this optimization problem is a very challenging non-convex problem. To address this difficulty, we transform the original problem to an equivalent problem by exploiting the channel duality. For the transformed problem,...
Real-Valued Covariance Vector Sparsity-Inducing DOA Estimation for Monostatic MIMO Radar
Directory of Open Access Journals (Sweden)
Xianpeng Wang
2015-11-01
Full Text Available In this paper, a real-valued covariance vector sparsity-inducing method for direction of arrival (DOA estimation is proposed in monostatic multiple-input multiple-output (MIMO radar. Exploiting the special configuration of monostatic MIMO radar, low-dimensional real-valued received data can be obtained by using the reduced-dimensional transformation and unitary transformation technique. Then, based on the Khatri–Rao product, a real-valued sparse representation framework of the covariance vector is formulated to estimate DOA. Compared to the existing sparsity-inducing DOA estimation methods, the proposed method provides better angle estimation performance and lower computational complexity. Simulation results verify the effectiveness and advantage of the proposed method.
Real-Valued Covariance Vector Sparsity-Inducing DOA Estimation for Monostatic MIMO Radar.
Wang, Xianpeng; Wang, Wei; Li, Xin; Liu, Jing
2015-11-10
In this paper, a real-valued covariance vector sparsity-inducing method for direction of arrival (DOA) estimation is proposed in monostatic multiple-input multiple-output (MIMO) radar. Exploiting the special configuration of monostatic MIMO radar, low-dimensional real-valued received data can be obtained by using the reduced-dimensional transformation and unitary transformation technique. Then, based on the Khatri-Rao product, a real-valued sparse representation framework of the covariance vector is formulated to estimate DOA. Compared to the existing sparsity-inducing DOA estimation methods, the proposed method provides better angle estimation performance and lower computational complexity. Simulation results verify the effectiveness and advantage of the proposed method.
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.
Vector and Axial Currents in Wilson Chiral Perturbation Theory
Aoki, Sinya; Sharpe, Stephen R
2009-01-01
We reconsider the construction of the vector and axial-vector currents in Wilson Chiral Perturbation Theory (WChPT), the low-energy effective theory for lattice QCD with Wilson fermions. We discuss in detail the finite renormalization of the currents that has to be taken into account in order to properly match the currents. We explicitly show that imposing the chiral Ward identities on the currents does, in general, affect the axial-vector current at O(a). As an application of our results we compute the pion decay constant to one loop in the two flavor theory. Our result differs from previously published ones.
Chen, Yang
2010-01-01
In this paper we compute two important information-theoretic quantities which arise in the application of multiple-input multiple-output (MIMO) antenna wireless communication systems: the distribution of the mutual information of multi-antenna Gaussian channels, and the Gallager random coding upper bound on the error probability achievable by finite-length channel codes. It turns out that the mathematical problem underpinning both quantities is the computation of certain Hankel determinants generated by deformed versions of classical weight functions. For single-user MIMO systems, it is a deformed Laguerre weight, whereas for multi-user MIMO systems it is a deformed Jacobi weight. We apply two different methods to characterize each of these Hankel determinants. First, we employ the ladder operators of the corresponding monic orthogonal polynomials to give an exact characterization of the Hankel determinants in terms of Painlev\\'{e} differential equations. This turns out to be a Painlev\\'{e} V for the single-u...
Non-gaussianity from the trispectrum and vector field perturbations
Valenzuela-Toledo, Cesar A
2009-01-01
We use the \\delta N formalism to study the trispectrum T_\\zeta of the primordial curvature perturbation \\zeta when the latter is generated by vector field perturbations, considering the tree-level and one-loop contributions. The level of non-gaussianity in the trispectrum, \\tau_{NL}, is calculated in this scenario and related to the level of non-gaussianity in the bispectrum, f_{NL}, and the level of statistical anisotropy in the power spectrum, g_\\zeta. Such consistency relations will put under test this scenario against future observations. Comparison with the expected observational bound on \\tau_{NL} from WMAP, for generic inflationary models, is done.
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 ...
Lie Symmetries of Quasihomogeneous Polynomial Planar Vector Fields and Certain Perturbations
Institute of Scientific and Technical Information of China (English)
Javier CHAVARRIGA; Isaac A. GARC(I)A
2005-01-01
In this work we study Lie symmetries of planar quasihomogeneous polynomial vector fields from different points of view, showing its integrability. Additionally, we show that certain perturbations of such vector fields which generalize the so-called degenerate infinity vector fields are also integrable.
On the non-Gaussian correlation of the primordial curvature perturbation with vector fields
DEFF Research Database (Denmark)
Kumar Jain, Rajeev; Sloth, Martin Snoager
2013-01-01
We compute the three-point cross-correlation function of the primordial curvature perturbation generated during inflation with two powers of a vector field in a model where conformal invariance is broken by a direct coupling of the vector field with the inflaton. If the vector field is identified...... with the electromagnetic field, this correlation would be a non-Gaussian signature of primordial magnetic fields generated during inflation. We find that the signal is maximized for the flattened configuration where the wave number of the curvature perturbation is twice that of the vector field and in this limit...
On the non-Gaussian correlation of the primordial curvature perturbation with vector fields
Jain, Rajeev Kumar
2012-01-01
We compute the three-point cross-correlation function of the primordial curvature perturbation generated during inflation with two powers of a vector field in a model where conformal invariance is broken by a direct coupling of the vector field with the inflaton. If the vector field is identified with the electromagnetic field, this correlation would be a non-Gaussian signature of primordial magnetic fields generated during inflation. We find that the signal is maximized for the flattened configuration where the wave number of the curvature perturbation is twice that of the vector field and in this limit, the magnetic non-linear parameter becomes as large as |b_{NL}| ~ 10^3. In the squeezed limit where the wave number of the curvature perturbation vanishes, our results agree with the magnetic consistency relation derived in arXiv:1207.4187.
On the non-Gaussian correlation of the primordial curvature perturbation with vector fields
Energy Technology Data Exchange (ETDEWEB)
Jain, Rajeev Kumar [Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, 24, Quai E. Ansermet, CH-1211 Genève 4 (Switzerland); Sloth, Martin S., E-mail: rajeev.jain@unige.ch, E-mail: sloth@cp3.dias.sdu.dk [CP3-Origins, Centre for Cosmology and Particle Physics Phenomenology, University of Southern Denmark, Campusvej 55, 5230 Odense M (Denmark)
2013-02-01
We compute the three-point cross-correlation function of the primordial curvature perturbation generated during inflation with two powers of a vector field in a model where conformal invariance is broken by a direct coupling of the vector field with the inflaton. If the vector field is identified with the electromagnetic field, this correlation would be a non-Gaussian signature of primordial magnetic fields generated during inflation. We find that the signal is maximized for the flattened configuration where the wave number of the curvature perturbation is twice that of the vector field and in this limit, the magnetic non-linear parameter becomes as large as |b{sub NL}| ∼ O(10{sup 3}). In the squeezed limit where the wave number of the curvature perturbation vanishes, our results agree with the magnetic consistency relation derived in arXiv:1207.4187.
Perturbative Correction to Transverse Ward-Takahashi Relation for the Vector Vertex
Institute of Scientific and Technical Information of China (English)
HE Han-Xin; YU Hong-Wei
2003-01-01
We re-derive exactly the transverse Ward-Takahashi relation for the vector vertex in momentum space.The result shows that this transverse Ward-Takahashi relation in momentum space involves a perturbative correction term. We demonstrate explicitly that this transverse Ward-Takahashi relation is satisfied indeed at one-loop order.
Non-gaussianity at tree- and one-loop levels from vector field perturbations
Valenzuela-Toledo, Cesar A; Lyth, David H
2009-01-01
We study the spectrum P_\\zeta and bispectrum B_\\zeta of the primordial curvature perturbation \\zeta when the latter is generated by scalar and vector field perturbations. The tree-level and one-loop contributions from vector field perturbations are worked out considering the possibility that the one-loop contributions may be dominant over the tree level terms (both (either) in P_\\zeta and (or) in B_\\zeta) and viceversa. The level of non-gaussianity in the bispectrum, f_{NL}, is calculated and related to the level of statistical anisotropy in the power spectrum, g_\\zeta. For very small amounts of statistical anisotropy in the power spectrum, the level of non-gaussianity may be very high, in some cases exceeding the current observational limit.
Scalar and vector perturbations in a universe with discrete and continuous matter sources
Eingorn, Maxim; Zhuk, Alexander
2016-01-01
We study a universe filled with dust-like matter in the form of discrete inhomogeneities (e.g., galaxies and their groups and clusters) and two sets of perfect fluids with linear and nonlinear equations of state, respectively. The background spacetime geometry is defined by the FLRW metric. In the weak gravitational field limit, we develop the first-order scalar and vector cosmological perturbation theory. Our approach works at all cosmological scales (i.e. sub-horizon and super-horizon ones) and incorporates linear and nonlinear effects with respect to energy density fluctuations. We demonstrate that the scalar perturbation (i.e. the gravitational potential) as well as the vector perturbation can be split into individual contributions from each matter source. Each of these contributions satisfies its own equation. The velocity-independent parts of the individual gravitational potentials are characterized by a finite time-dependent Yukawa interaction range being the same for each individual contribution. We a...
Takeuchi, Keigo; Kawabata, Tsutomu
2012-01-01
Multiple-input multiple-output (MIMO) broadcast channels (BCs) (MIMO-BCs) with perfect channel state information (CSI) at the transmitter are considered. As joint user selection (US) and vector precoding (VP) (US-VP) with zero-forcing transmit beamforming (ZF-BF), US and continuous VP (CVP) (US-CVP) and data-dependent US (DD-US) are investigated. The replica method, developed in statistical physics, is used to analyze the energy penalties for the two US-VP schemes in the large-system limit, where the number of users, the number of selected users, and the number of transmit antennas tend to infinity with their ratios kept constant. Four observations are obtained in the large-system limit: First, the assumptions of replica symmetry (RS) and 1-step replica symmetry breaking (1RSB) for DD-US can provide acceptable approximations for low and moderate system loads, respectively. Secondly, DD-US outperforms CVP with random US in terms of the energy penalty for low-to-moderate system loads. Thirdly, the asymptotic en...
Topological features of vector vortex beams perturbed with uniformly polarized light
D'Errico, Alessio; Piccirillo, Bruno; de Lisio, Corrado; Cardano, Filippo; Marrucci, Lorenzo
2016-01-01
Optical singularities manifesting at the center of vector vortex beams are unstable, since their topological charge is higher than the lowest value permitted by Maxwell's equations. Inspired by conceptually similar phenomena occurring in the polarization pattern characterizing the skylight, we show how perturbations that break the symmetry of radially symmetric vector beams lead to the formation of a pair of fundamental and stable singularities, i.e. points of circular polarization. We prepare a superposition of a radial (or azimuthal) vector beam and a uniformly linearly polarized Gaussian beam; by varying the amplitudes of the two fields, we control the formation of pairs of these singular points and their spatial separation. We complete this study by applying the same analysis to vector vortex beams with higher topological charges, and by investigating the features that arise when increasing the intensity of the Gaussian term. Our results can find application in the context of singularimetry, where weak fi...
Perturbations of slowly rotating black holes: massive vector fields in the Kerr metric
Pani, Paolo; Gualtieri, Leonardo; Berti, Emanuele; Ishibashi, Akihiro
2012-01-01
We discuss a general method to study linear perturbations of slowly rotating black holes which is valid for any perturbation field, and particularly advantageous when the field equations are not separable. As an illustration of the method we investigate massive vector (Proca) perturbations in the Kerr metric, which do not appear to be separable in the standard Teukolsky formalism. Working in a perturbative scheme, we discuss two important effects induced by rotation: a Zeeman-like shift of nonaxisymmetric quasinormal modes and bound states with different azimuthal number m, and the coupling between axial and polar modes with different multipolar index l. We explicitly compute the perturbation equations up to second order in rotation, but in principle the method can be extended to any order. Working at first order in rotation we show that polar and axial Proca modes can be computed by solving two decoupled sets of equations, and we derive a single master equation describing axial perturbations of spin s=0 and ...
Analysis of MIMO antenna array based on electromagnetic vector sensor%基于电磁矢量传感器的 MIMO 天线阵列系统研究
Institute of Scientific and Technical Information of China (English)
周杰; 邱琳; 菊池久和
2013-01-01
EVS(electromagnetic vetor sensor) signal processing method was combined with traditional MIMO signal processing method and three-dimensional channel model of multi-antenna array was set up. The algorithm of multiple signal classification (MUSIC) was adopted to make spatial spectrum estimation for direction of arrival (DOA) signal, analytical expressions of three-dimensional spatial channel was derived base on EVS for MIMO receiver system and the relationship between EVS signal processing and MIMO multipath channel correlation was clarified. To compare with tra-ditional MIMO antenna array, EVS array possesses abilities of obtaining multidimensional polarization information, processing spatial and polarization domain for arrival signal and degrading effects of spatial factors on MIMO channel capacity. Theoretical analysis and simulation results indicate that EVS array provide more advantages than traditional scalar sensor array on enhancing MIMO system performance.% 将电磁矢量传感器(EVS, electromagnetic vetor sensor)信号处理法与传统 MIMO 信号处理有机地结合，建立了基于 EVS 的多天线三维信道模型。采用多重信号分类(MUSIC, multiple signal classification)算法对 MIMO 的达波信号方向(DOA, direction of arrival)进行空间谱估计，导出基于 EVS 的三维空间信道解析式，阐明了 EVS 信号处理与 MIMO 多径信道相关性的关系。与传统标量传感器阵列(SSA, scalar sensor array)MIMO 天线阵列比较， EVS 阵列能获取达波信号的多维极化信息，同时具有空间域和极化信号处理能力。因此可缓解空间多径信道相关性，使空间极化分量的相关性趋于零值，而且使 MIMO 系统性能受空间结构的影响较小。理论分析和仿真结果表明在提高 MIMO 天线系统性能上，基于 EVS 阵列的系统比 SSA 系统具有更高的优越性。
A general theory of linear cosmological perturbations: scalar-tensor and vector-tensor theories
Lagos, Macarena; Ferreira, Pedro G; Noller, Johannes
2016-01-01
We present a method for parametrizing linear cosmological perturbations of theories of gravity, around homogeneous and isotropic backgrounds. The method is sufficiently general and systematic that it can be applied to theories with any degrees of freedom (DoFs) and arbitrary gauge symmetries. In this paper, we focus on scalar-tensor and vector-tensor theories, invariant under linear coordinate transformations. In the case of scalar-tensor theories, we use our framework to recover the simple parametrizations of linearized Horndeski and "Beyond Horndeski" theories, and also find higher-derivative corrections. In the case of vector-tensor theories, we first construct the most general quadratic action for perturbations that leads to second-order equations of motion, which propagates two scalar DoFs. Then we specialize to the case in which the vector field is time-like (\\`a la Einstein-Aether gravity), where the theory only propagates one scalar DoF. As a result, we identify the complete forms of the quadratic act...
MATHEMATICAL SIMULATION OF SENSORLESS VECTOR CONTROL INDUCTION MOTOR UNDER PARAMETRIC PERTURBATIONS
Directory of Open Access Journals (Sweden)
D. S. Odnolko
2015-01-01
Full Text Available Developed a mathematical simulation model of the system of indirect sensorless vector control induction motor. The studies of the sensitivity of the electric drive system to parametric perturbations, in particular to the change in resistance of the stator and rotor. Presents an analysis of quality of work the system: estimation accuracy of the angular velocity of the rotor and the stability of the dynamic properties of the system, using the algorithms of parametric identification of an induction motor and without them.
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.
Yu, Pei; Han, Maoan
2013-04-01
In this paper, we show that a Z2-equivariant 3rd-order Hamiltonian planar vector fields with 3rd-order symmetric perturbations can have at least 10 limit cycles. The method combines the general perturbation to the vector field and the perturbation to the Hamiltonian function. The Melnikov function is evaluated near the center of vector field, as well as near homoclinic and heteroclinic orbits.
The Determination of an Intermediate Perturbed Orbit from Two Position Vectors
Shefer, V. A.
2003-05-01
Based on the theory of intermediate orbits developed earlier by the author of this paper, a new approach is proposed to the solution of the problem of finding the orbit of a celestial body with the use of two position vectors of this body and the corresponding time interval. This approach makes it possible to take into account the main part of perturbations. The orbit is constructed, the motion along which is a combination of two motions: the uniform motion along a straight line of a fictitious attracting center, whose mass varies according to the first Meshchersky law, and the motion around this center. The latter is described by the equations of the Gylden-Meshchersky problem. The parameters of the constructed orbit are chosen so that their limiting values at any reference epoch determine a superosculating intermediate orbit with third-order tangency. The accuracy of approximation of the perturbed motion by the orbits calculated by the classical Gauss method and the new method is illustrated by an example of the motion of the unusual minor planet 1566 Icarus. Comparison of the results obtained shows that the new method has obvious advantages over the Gauss method. These advantages are especially prominent in cases where the angular distances between the reference positions are small.
Feng, Jie; Ding, Ruiqiang; Li, Jianping; Liu, Deqiang
2016-09-01
The breeding method has been widely used to generate ensemble perturbations in ensemble forecasting due to its simple concept and low computational cost. This method produces the fastest growing perturbation modes to catch the growing components in analysis errors. However, the bred vectors (BVs) are evolved on the same dynamical flow, which may increase the dependence of perturbations. In contrast, the nonlinear local Lyapunov vector (NLLV) scheme generates flow-dependent perturbations as in the breeding method, but regularly conducts the Gram-Schmidt reorthonormalization processes on the perturbations. The resulting NLLVs span the fast-growing perturbation subspace efficiently, and thus may grasp more components in analysis errors than the BVs. In this paper, the NLLVs are employed to generate initial ensemble perturbations in a barotropic quasi-geostrophic model. The performances of the ensemble forecasts of the NLLV method are systematically compared to those of the random perturbation (RP) technique, and the BV method, as well as its improved version—the ensemble transform Kalman filter (ETKF) method. The results demonstrate that the RP technique has the worst performance in ensemble forecasts, which indicates the importance of a flow-dependent initialization scheme. The ensemble perturbation subspaces of the NLLV and ETKF methods are preliminarily shown to catch similar components of analysis errors, which exceed that of the BVs. However, the NLLV scheme demonstrates slightly higher ensemble forecast skill than the ETKF scheme. In addition, the NLLV scheme involves a significantly simpler algorithm and less computation time than the ETKF method, and both demonstrate better ensemble forecast skill than the BV scheme.
Phased-MIMO Radar: A Tradeoff Between Phased-Array and MIMO Radars
Hassanien, Aboulnasr
2009-01-01
We propose a new technique for multiple-input multiple-output (MIMO) radar with colocated antennas which we call phased-MIMO radar. The new technique enjoys the advantages of MIMO radar without sacrificing the main advantage of phased-array radar which is the coherent processing gain at the transmitting side. The essence of the proposed technique is to partition the transmitting array into a number of subarrays that are allowed to overlap. Then, each subarray is used to coherently transmit a waveform which is orthogonal to the waveforms transmitted by other subarrays. Coherent processing gain can be achieved by designing a weight vector for each subarray to form a beam towards a certain direction in space. Moreover, the subarrays are combined jointly to form a MIMO radar resulting in higher resolution capabilities. The substantial improvements offered by the proposed phased-MIMO radar technique as compared to previous techniques are demonstrated analytically and by simulations through analysis of the correspo...
Low Complexity Receiver Design for MIMO-Radar
Ahmed, Sajid
2012-09-08
In this work, an algorithm for the multiple-input multiple-output (MIMO) radar is proposed. It has low computational complexity compared to the available schemes, and relatively low side-lobe-levels in the receive beampattern compared to the phased-array and MIMO-radar. In the proposed algorithm, the received signal vector of MIMO-radar is divided into sub-vectors, and each sub-vector is multiplied with the corresponding weight vector. The number of sub-vectors and weight vectors are optimally found to maximise the received signal power from the target of interest direction. The proposed scheme can be effectively applied in passive radars to minimise the side-lobe levels and place deep nulls for interferers in the receive beampattern. Simulation results show that the proposed scheme has relatively lower side lobe levels and better detection capabilities compared to MIMO-radar and phased-array.
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....
Institute of Scientific and Technical Information of China (English)
JIANG Zhina; MU Mu
2009-01-01
The authors apply the technique of conditional nonlinear optimal perturbations (CNOPs) as a means of providing initial perturbations for ensemble forecasting by using a barotropic quasi-gcostrophic (QG) model in a perfect-model scenario. Ensemble forecasts for the medium range (14 days) are made from the initial states perturbed by CNOPs and singular vectors (SVs). 13 different cases have been chosen when analysis error is a kind of fast growing error. Our experiments show that the introduction of CNOP provides better forecast skill than the SV method. Moreover, the spread-skill relationship reveals that the ensemble samples in which the first SV is replaced by CNOP appear supcrior to those obtained by SVs from day 6 to day 14. Rank diagrams are adopted to compare the new method with the SV approach. The results illustrate that the introduction of CNOP has higher reliability for medium-range ensemble forecasts.
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...
Geng, L S; Vacas, M J Vicente
2009-01-01
We calculate the SU(3)-breaking corrections to the hyperon vector coupling $f_1(0)$ up to $\\mathcal{O}(p^4)$ in covariant baryon chiral perturbation theory with dynamical octet and decuplet contributions. We find that the decuplet contributions are of similar or even larger size than the octet ones. Combining both, we predict positive SU(3)-breaking corrections to all the four independent $f_1(0)$'s (assuming isospin symmetry), which are consistent, within uncertainties, with the latest results form large $N_c$ fits, chiral quark models, and quenched lattice QCD calculations.
A NOVEL INDOOR GEO-LOCATION METHOD USING MIMO ARRAY
Institute of Scientific and Technical Information of China (English)
Sun Guolin; Guo Wei
2006-01-01
In a Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) based Wireless Local Area Network (WLAN) system, both Access Points (Aps) and Mobile Terminals (MTs) are configured with multiple antennas, to make novel indoor geo-location method possible. In this paper, we presented a novel Least Square Support Vector Machine (LS-SVM) based data fusion algorithm to fuse signal strength measurements for indoor geo-location using only a single AP with MIMO arrays. We evaluate our proposed algorithms under indoor environments by MATLAB simulations. Simulation results show that our MIMO-based algorithm is superior to conventional least square algorithm.
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.
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,...
MIMO/SA Multi-antenna Space-time Channel Modeling%MIMO/SA多天线空时信道建模
Institute of Scientific and Technical Information of China (English)
吕郡陵; 郭爱煌
2012-01-01
Based on correlation matrix method. Multiple-input and Multiple-output(MIMO) channel coefficient matrix can be obtained by calculating the correlation coefficient between two antennas and MIMO correlation matrix. The steering vector and beam-forming vector of Smart Antenna(SA) are added to the MIMO channel coefficient matrix to form MIMO/SA channel matrix, so that MIMO/SA multi-antenna space-time channel is modeled. A channel simulation platform is established to simulate and analyze MIMO/SA channel in time domain, frequency domain and space domain. Simulation results show that the model has a good channel directivity gain and the channel properties in space, time and frequency meet the demands of 3GPP TR 25.996, and it is useful for designing and optimizing MIMO/SA multi-antenna system and the analysis of channel capacity.%运用相关矩阵法,通过计算2根天线之间的相关系数、多输入多输出(MIMO)的相关矩阵,得到MIMO信道系数矩阵,在其中加入智能天线(SA)的导向向量和赋形向量,得到MIMO/SA矩阵,由此实现对MIMO/SA多天线空时信道的建模.利用Matlab搭建一个仿真平台,从空间、时间、频率3个方面分析MIMO/SA多天线信道模型,结果表明,该模型具有较好的信道方向性增益,信道的空时频特性符合3GPP 25.996的要求,可用于MIMO/SA多天线的设计、优化和信道容量分析.
Geng, L S; Vacas, M J Vicente
2009-01-01
We report on a recent study of the SU(3)-breaking corrections to the hyperon vector coupling $f_1(0)$ up to $\\mathcal{O}(p^4)$ in covariant baryon chiral perturbation theory with dynamical octet and decuplet contributions. The decuplet contributions are taken into account for the first time in a covariant ChPT study and are found of similar or even larger size than the octet ones. We predict positive SU(3)-breaking corrections to all the four independent $f_1(0)$'s (assuming isospin symmetry), which are consistent, within uncertainties, with the latest results from large $N_c$ fits, chiral quark models, and quenched lattice QCD calculations. We also discuss briefly the implications of our results for the extraction of $V_{us}$ from hyperon decay data.
Institute of Scientific and Technical Information of China (English)
Yang Xinsong; Cao Jinde
2012-01-01
In this article,we consider the global chaotic synchronization of general coupled neural networks,in which subsystems have both discrete and distributed delays.Stochastic perturbations between subsystems are also considered.On the basis of two simple adaptive pinning feedback control schemes,Lyapunov functional method,and stochastic analysis approach,several sufficient conditions are developed to guarantee global synchronization of the coupled neural networks with two kinds of delay couplings,even if only partial states of the nodes are coupled.The outer-coupling matrices may be symmetric or asymmetric.Unlike existing results that an isolate node is introduced as the pinning target,we pin to help the network realizing synchronization without introducing any isolate node when the network is not synchronized.As a by product,sufficient conditions under which the network realizes synchronization without control are derived.Numerical simulations confirm the effectiveness of the obtained results.
2016-01-01
Documento que contiene la explicación sobre las temáticas de Sistemas coordenados, Cantidades vectoriales y escalares, Algunas propiedades de los vectores, Componentes de un vector y vectores unitarios
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.
Acoustic MIMO signal processing
Huang, Yiteng; Chen, Jingdong
2006-01-01
A timely and important book addressing a variety of acoustic signal processing problems under multiple-input multiple-output (MIMO) scenarios. It uniquely investigates these problems within a unified framework offering a novel and penetrating analysis.
Hierarchical Codebook Design for Massive MIMO
Directory of Open Access Journals (Sweden)
Xin Su
2015-02-01
Full Text Available The Research of Massive MIMO is an emerging area, since the more antennas the transmitters or receivers equipped with, the higher spectral efficiency and link reliability the system can provide. Due to the limited feedback channel, precoding and codebook design are important to exploit the performance of massive MIMO. To improve the precoding performance, we propose a novel hierarchical codebook with the Fourier-based perturbation matrices as the subcodebook and the Kerdock codebook as the main codebook, which could reduce storage and search complexity due to the finite a lphabet. Moreover, t o f urther r educe t he search complexity and feedback overhead without noticeable performance degradation, we use an adaptive selection algorithm to decide whether to use the subcodebook. Simulation results show that the proposed codebook has remarkable performance gain compared to the conventional Kerdock codebook, without significant increase in feedback overhead and search complexity.
DEFF Research Database (Denmark)
2008-01-01
A Coding/Modulating units (200-1-200-N) outputs modulated symbols by modulating coding bit streams based on certain modulation scheme. The limited perturbation vector is calculated by using distribution of perturbation vectors. The original constellation points of modulated symbols are extended...
DEFF Research Database (Denmark)
2008-01-01
A Coding/Modulating units (200-1-200-N) outputs modulated symbols by modulating coding bit streams based on certain modulation scheme. The limited perturbation vector is calculated by using distribution of perturbation vectors. The original constellation points of modulated symbols are extended t...
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...
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.
CR-Calculus and adaptive array theory applied to MIMO random vibration control tests
Musella, U.; Manzato, S.; Peeters, B.; Guillaume, P.
2016-09-01
Performing Multiple-Input Multiple-Output (MIMO) tests to reproduce the vibration environment in a user-defined number of control points of a unit under test is necessary in applications where a realistic environment replication has to be achieved. MIMO tests require vibration control strategies to calculate the required drive signal vector that gives an acceptable replication of the target. This target is a (complex) vector with magnitude and phase information at the control points for MIMO Sine Control tests while in MIMO Random Control tests, in the most general case, the target is a complete spectral density matrix. The idea behind this work is to tailor a MIMO random vibration control approach that can be generalized to other MIMO tests, e.g. MIMO Sine and MIMO Time Waveform Replication. In this work the approach is to use gradient-based procedures over the complex space, applying the so called CR-Calculus and the adaptive array theory. With this approach it is possible to better control the process performances allowing the step-by-step Jacobian Matrix update. The theoretical bases behind the work are followed by an application of the developed method to a two-exciter two-axis system and by performance comparisons with standard methods.
DEFF Research Database (Denmark)
Boeriis, Morten; van Leeuwen, Theo
2017-01-01
This article revisits the concept of vectors, which, in Kress and van Leeuwen’s Reading Images (2006), plays a crucial role in distinguishing between ‘narrative’, action-oriented processes and ‘conceptual’, state-oriented processes. The use of this concept in image analysis has usually focused...... on the most salient vectors, and this works well, but many images contain a plethora of vectors, which makes their structure quite different from the linguistic transitivity structures with which Kress and van Leeuwen have compared ‘narrative’ images. It can also be asked whether facial expression vectors...... should be taken into account in discussing ‘reactions’, which Kress and van Leeuwen link only to eyeline vectors. Finally, the question can be raised as to whether actions are always realized by vectors. Drawing on a re-reading of Rudolf Arnheim’s account of vectors, these issues are outlined...
MIMO Throughput Effectiveness for Basic MIMO OTA Compliance Testing
Directory of Open Access Journals (Sweden)
Adoración Marín-Soler
2012-01-01
Full Text Available During the March 2011 meeting of the CTIA MIMO OTA Subgroup (MOSG, the members agreed that the subgroup should first determine “what” aspects of a MIMO-capable device require evaluation; then the group should determine “how” to go about making these measurements. In subsequent meetings of MOSG, new yet-unnamed figures of merit were asked for in order to provide a solution to the carriers' requirements for LTE MIMO OTA evaluation. Furthermore, the December 2011 3GPP RAN4 status report on LTE MIMO OTA listed the evaluation of the use of statistical performance analysis in order to minimize test time and help ensure accurate performance assessment as an open issue. This contribution addresses these petitions by providing four new figures of merit, which could serve the purpose of evaluating the operators' top priorities for MIMO OTA compliance testing. The new figures of merit are MIMO Throughput Effectiveness (MTE, MIMO Device Throughput Effectiveness (MDTE, MIMO Throughput Gain (MTG, and MIMO Device Throughput Gain (MDTG. In this paper, MTE is evaluated using the recently available LTE MIMO OTA RR data from 3GPP.
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
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.
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).
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...
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...
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....
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.
PERBANDINGAN PERFORMANSI SISTEM MC-SS MIMO DENGAN OFDM MIMO
Directory of Open Access Journals (Sweden)
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
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...
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...
MIMO to LS-MIMO: A road to realization of 5G
Koppati, Naveena; Pavani, K.; Sharma, Dinesh; Sharma, Purnima K.
2017-07-01
MIMO means multiple inputs multiple outputs. As it refers MIMO is a RF technology used in many new technologies these days to increase link capacity and spectral efficiency. MIMO is used in Wi-Fi, LTE, 4G, 5G and other wireless technologies. This paper describes the earlier history of MIMO-OFDM and the antenna beam forming development in MIMO and types of MIMO. Also this treatise describes several decoding algorithms. The MIMO combined with OFDM increases the channel capacity. But the main problem is in estimating the transmitted signal from the received signal. So the channel knowledge is to be known in estimating the channel capacity. The advancement in MIMO-OFDM is Massive MIMO which is beneficial in providing additional data capacity in the increased traffic environment is described. In this memoir various application scenarios of LS-MIMO which increases the capacity are discussed.
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.
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...
Joint Unitary Triangularization for MIMO Networks
Khina, Anatoly; Erez, Uri
2010-01-01
This work considers communication networks where individual links can be described as MIMO channels. Unlike orthogonal modulation methods (such as the singular-value decomposition), we allow interference between sub-channels, which can be removed by the receivers via successive cancellation. The degrees of freedom earned by this relaxation are used for obtaining a basis which is simultaneously good for more than one link. Specifically, we derive necessary and sufficient conditions for shaping the ratio vector of sub-channel gains of two broadcast-channel receivers. We then apply this to two scenarios: First, in digital multicasting we present a practical capacity-achieving scheme which only uses scalar codes and linear processing. Then, we consider the joint source-channel problem of transmitting a Gaussian source over a two-user MIMO channel, where we show the existence of non-trivial cases, where the optimal distortion pair (which for high signal-to-noise ratios equals the point-to-point distortions of the ...
Nucleon and Delta axial-vector couplings in 1/N{sub c}-Baryon Chiral Perturbation Theory
Energy Technology Data Exchange (ETDEWEB)
Goity, Jose Luis [JLAB; Calle Cordon, Alvaro [JLAB
2013-08-01
In this contribution, baryon axial-vector couplings are studied in the framework of the combined 1/N{sub c} and chiral expansions. This framework is implemented on the basis of the emergent spin-flavor symmetry in baryons at large N{sub c} and HBChPT, and linking both expansions ({xi}-expansion), where 1/N{sub c} is taken to be a quantity order p. The study is carried out including one-loop contributions, which corresponds to order xi to the third for baryon masses and order {xi} square for the axial couplings.
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...
Dynamic Beamforming for Three-Dimensional MIMO Technique in LTE-Advanced Networks
Directory of Open Access Journals (Sweden)
Yan Li
2013-01-01
Full Text Available MIMO system with large number of antennas, referred to as large MIMO or massive MIMO, has drawn increased attention as they enable significant throughput and coverage improvement in LTE-Advanced networks. However, deploying huge number of antennas in both transmitters and receivers was a great challenge in the past few years. Three-dimensional MIMO (3D MIMO is introduced as a promising technique in massive MIMO networks to enhance the cellular performance by deploying antenna elements in both horizontal and vertical dimensions. Radio propagation of user equipments (UE is considered only in horizontal domain by applying 2D beamforming. In this paper, a dynamic beamforming algorithm is proposed where vertical domain of antenna is fully considered and beamforming vector can be obtained according to UEs’ horizontal and vertical directions. Compared with the conventional 2D beamforming algorithm, throughput of cell edge UEs and cell center UEs can be improved by the proposed algorithm. System level simulation is performed to evaluate the proposed algorithm. In addition, the impacts of downtilt and intersite distance (ISD on spectral efficiency and cell coverage are explored.
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.
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.
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.
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...
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...
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.
Multiuser MIMO Channel Estimation
Directory of Open Access Journals (Sweden)
G.Indumathi
2016-05-01
Full Text Available In this paper, three beamforming design are considered for multi user MIMO system. First, transmit beamformers are fixed and the receive (RX beamformers are calculated. Transmit beamformer (TX-BFis projectedas a null space of appropriate channels. It reduces the interference for each user. Then the receiver beamformer is determined which maximize the SNR. This beamforming design provides less computation time. The second case is joint TX and RX beamformer for SNR maximization. In this transmitter and receiver beamformer are calculated using extended alternating optimization (EAO algorithm. The third one is joint transmitter and receiver beamforming for SNR and SINR maximization using EAO algorithm. This algorithm provides better error performance and sum rate performance. All the design cases are simulated by using standard multipath channel model. Our simulation results illustrate that compared to the least square design and zero forcing design, the joint TX and RX beamforming design using EAO algorithm provides faster beamforming and improved error performance and sum rate.
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.
Institute of Scientific and Technical Information of China (English)
许继军; 姚堃; 彭光勇; 谢芳艺; 丁传林; 朱建中; 秦健
2002-01-01
ObjectiveTo study the effects of dendritic cells (DC) transfected with recombinant vaccinia virus encoding Epstein-Barr virus (EBV) latent membrane protein 2A(LMP2A) gene,and to provide evidence for further investigation on the therapeutic vaccines against EBV-associated malignancies.MethodsMature DC were transfected with EBV-LMP2A recombinant vaccinia virus (rVV-LMP2A).Before and after the transfection,the expression of surface antigens on mature DC including CD1a,CD83,CD40,CD80,HLA-DR was measured by fluorescence activated cell sorter (FACS) and the function of DC to stimulate allogeneic T cells proliferation was measured by mixed leukocyte reactions (MLR).ResultsLMP2A protein was highly expressed (66.1%) in DC after the transfection of rVV-LMP2A.No significant changes in the primary surface antigens expression and in the MLR were detected during the transfection.Transfected DC still had strong potential in stimulating the proliferation of allogeneic T cells.ConclusionRecombinant vaccinia virus was an effective and non-perturbing vector to mediate the transfection of LMP2A into DC.The functions of mature DC were not affected significantly by the transfection of Vac-LMP2A.This study could provide evidence for the further immunotherapy of EBV-associated malignancies,e.g.nasopharyngeal carcinoma (NPC).``
Institute of Scientific and Technical Information of China (English)
许继军; 姚Kun; 等
2002-01-01
Objective To study the effects of dendritic cells(DC) transfected with recombinant vaccinia virus encoding Epstein-Barr virus(EBV) latent membrane protein 2A(LMP2A) gene,and to provide evidence for further investigation on the therapeutic uaccines against EBV-associated malignancies.Methods Mature DC were transfected with EVB-LMP2A recombinant vaccinia virus(rVV-LMP2A).Before and after the transfection,the expression of surface antigens on mature DC including CD1a,CD83,CD40,CD80,HLA-DR was measured by fluorescence activated cell sorter(FACS) and the function of DC to stimulate allogeneic T cells proliferation was measured by mixed leukocyte reactions(MLR).Results LMP2A protein was highly expressed (66.1%) in DC after the transfection of rVV-LMP2A.No significant changes in the primary surface antigens expression and in the MLR were detected during the transfection.Transfected DC still had strong potential in stimulating the proliferation of allogeneic T cells.Conclusion Recombinant vaccinia virus was an effective and non-perturbing vector to mediate the transfection of LMP2A into DC.The functions of mature DC were not affected significantly by the transfection of Vac-LMP2A.This study could provide evidence for the further immunotherapy of EBV-associated malignancies,e.g.nasopharyngeal carcinoma(NPC).
Shefer, V. A.; Shefer, O. V.
2016-05-01
Intermediate perturbed orbits, which were proposed earlier by the first author and are calculated based on three position vectors and three measurements of angular coordinates of a small celestial body, are examined. Provided that the reference time interval encompassing the measurements is short, these orbits are close in the accuracy of approximation of actual motion to an orbit with fourth-order tangency. The shorter the reference time interval is, the better is the approximation. The laws of variation of the errors of methods for constructing such intermediate orbits with the length of the reference time interval are formulated. According to these laws, the rate of convergence of the methods to an exact solution in the process of shortening of the reference time interval is, in general, three orders of magnitude higher than that of conventional methods relying on an unperturbed Keplerian orbit. The considered orbits are among the most accurate of their class that is defined by the order of tangency. The obtained theoretical results are verified by numerical experiments on determining the orbit of 99942 Apophis.
On Cellular MIMO Channel Capacity
Adachi, Koichi; Adachi, Fumiyuki; Nakagawa, Masao
To increase the transmission rate without bandwidth expansion, the multiple-input multiple-output (MIMO) technique has recently been attracting much attention. The MIMO channel capacity in a cellular system is affected by the interference from neighboring co-channel cells. In this paper, we introduce the cellular channel capacity and evaluate its outage capacity, taking into account the frequency-reuse factor, path loss exponent, standard deviation of shadowing loss, and transmission power of a base station (BS). Furthermore, we compare the cellular MIMO downlink channel capacity with those of other multi-antenna transmission techniques such as single-input multiple-output (SIMO) and space-time block coded multiple-input single-output (STBC-MISO). We show that the optimum frequency-reuse factor F that maximizes 10%-outage capacity is 3 and both 50%- and 90%-outage capacities is 1 irrespective of the type of multi-antenna transmission technique, where q%-outage capacity is defined as the channel capacity that gives an outage probability of q%. We also show that the cellular MIMO channel capacity is always higher than those of SIMO and STBC-MISO.
Beamforming with Reduced Complexity in MIMO Cooperative Cognitive Radio Networks
Directory of Open Access Journals (Sweden)
Mehdi Ghamari Adian
2014-01-01
Full Text Available An approach for beamforming with reduced complexity in MIMO cooperative cognitive radio networks (MIMO-CCRN is presented. Specifically, a suboptimal approach with reduced complexity is proposed to jointly determine the transmit beamforming (TB and cooperative beamforming (CB weight vectors along with antenna subset selection in MIMO-CCRN. Two multiantenna secondary users (SU constitute the desired link, one acting as transmitter (SU TX and the other as receiver (SU RX and they coexist with single-antenna primary and secondary users. Some of single antenna secondary users are recruited by desired link as cooperative relay. The maximization of the achievable rates in the desired link is the objective of this work, provided to interference constraints on the primary users are not violated. The objective is achieved by exploiting transmit beamforming at SU TX, cooperation of some secondary users, and cooperative beamforming. Meanwhile, the costs associated with RF chains at the radio front end at SU RX are reduced. Through simulations, it is shown that better performance in the desired link is attained, as a result of cooperation of SUs.
Balancing Egoism and Altruism on MIMO Interference Channel
Ho, Zuleita Ka Ming
2009-01-01
This paper considers the so-called multiple-input-multiple-output interference channel (MIMO-IC) which has relevance in applications such as multi-cell coordination in cellular networks as well as spectrum sharing in cognitive radio networks among others. We address the design of precoding (i.e. beamforming) vectors at each sender with the aim of striking a compromise between beamforming gain at the intended receiver (Egoism) and the mitigation of interference created towards other receivers (Altruism). Combining egoistic and altruistic beamforming has been shown previously to be instrumental to optimizing the rates in a multiple-input-single-output interference channel MISO-IC (i.e. where receivers have no interference canceling capability) [5], [7]. Here we explore these game-theoretic concepts in the more general context of MIMO channels and using the framework of Bayesian games [17], allowing us to derive (semi-)distributed precoding techniques. We draw parallels with existing work on the MIMO-IC, includi...
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....
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...
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....
Filter Bank Multicarrier for Massive MIMO
Farhang, Arman,; Marchetti, Nicola; Doyle, Linda E.; Farhang-Boroujeny, Behrouz
2014-01-01
This paper introduces filter bank multicarrier (FBMC) as a potential candidate in the application of massive MIMO communication. It also points out the advantages of FBMC over OFDM (orthogonal frequency division multiplexing) in the application of massive MIMO. The absence of cyclic prefix in FBMC increases the bandwidth efficiency. In addition, FBMC allows carrier aggregation straightforwardly. Self-equalization, a property of FBMC in massive MIMO that is introduced in this paper, has the im...
Balancing Egoism and Altruism on the Interference Channel: The MIMO case
Ho, Zuleita K M
2010-01-01
This paper considers the so-called MIMO interference channel. This situation has relevance in applications such as multi-cell coordination in cellular networks as well as spectrum sharing in cognitive radio networks among others. We address the design of precoding (i.e. beamforming) vectors at each sender with the aim of striking a compromise between beamforming gain at the intended receiver (Egoism) and the mitigation of interference created towards other receivers (Altruism). Combining egoistic and altruistic beamforming has been shown previously to be instrumental to optimizing the rates in a MISO interference channel (i.e. where receivers have no interference canceling capability) . Here we explore these game-theoretic concepts in the more general context of MIMO channels and using the framework of Bayesian games, allowing us to derive (semi-)distributed precoding techniques. We draw parallels with existing work on the MIMO interference channel, including rate-optimizing and interference-alignement precod...
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.
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....
MIMO Radar Using Compressive Sampling
Yu, Yao; Poor, H Vincent
2009-01-01
A MIMO radar system is proposed for obtaining angle and Doppler information on potential targets. Transmitters and receivers are nodes of a small scale wireless network and are assumed to be randomly scattered on a disk. The transmit nodes transmit uncorrelated waveforms. Each receive node applies compressive sampling to the received signal to obtain a small number of samples, which the node subsequently forwards to a fusion center. Assuming that the targets are sparsely located in the angle- Doppler space, based on the samples forwarded by the receive nodes the fusion center formulates an l1-optimization problem, the solution of which yields target angle and Doppler information. The proposed approach achieves the superior resolution of MIMO radar with far fewer samples than required by other approaches. This implies power savings during the communication phase between the receive nodes and the fusion center. Performance in the presence of a jammer is analyzed for the case of slowly moving targets. Issues rel...
Comparison of mimo radar concepts: Detection performance
Rossum, W.L. van; Huizing, A.G.
2007-01-01
In this paper, four different array radar concepts are compared: pencil beam, floodlight, monostatic MIMO, and multistatic MIMO. The array radar concepts show an increase in complexity accompanied by an increase in diversity. The comparison between the radar concepts is made by investigating the
Multi-User MIMO Across Small Cells
DEFF Research Database (Denmark)
Finn, Danny; Ahmadi, Hamed; Cattoni, Andrea Fabio
2014-01-01
The main contribution of this work is the proposal and assessment of the MU-MIMO across Small Cells concept. MU-MIMO is the spatial multiplexing of multiple users on a single time-frequency resource. In small cell networks, where the number of users per cell is low, finding suitable sets of users...
Comparison of mimo radar concepts: Detection performance
Rossum, W.L. van; Huizing, A.G.
2007-01-01
In this paper, four different array radar concepts are compared: pencil beam, floodlight, monostatic MIMO, and multistatic MIMO. The array radar concepts show an increase in complexity accompanied by an increase in diversity. The comparison between the radar concepts is made by investigating the det
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...
Comparison of mimo radar concepts: Detection performance
Rossum, W.L. van; Huizing, A.G.
2007-01-01
In this paper, four different array radar concepts are compared: pencil beam, floodlight, monostatic MIMO, and multistatic MIMO. The array radar concepts show an increase in complexity accompanied by an increase in diversity. The comparison between the radar concepts is made by investigating the det
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.
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.
Precoding for Multiuser Spatial Multiplexing MIMO Downlink
Institute of Scientific and Technical Information of China (English)
ZHANG Bijun; ZHU Guangxi; LIU Yingzhuang
2006-01-01
Previous precoding algorithms have concentrated on the single user scenario where the precoding scheme assumes perfect channel state information (CSI) at the transmitter or on limited feedback techniques, such as channel quantization or limited feedback signal designs. This paper proposes a novel unitary downlink precoding design scheme for multiuser spatial multiplexing multiple-input multiple-output (MIMO) systems. With the perfect CSI available at the transmitter and the linear decoder at the receiver, the cost function was constructed based on the minimum average probability of vector symbol error and the design method of the precoding matrices was given. These proposed precoding matrices can completely eliminate co-channel interference for each user at the transmitter, and each user will eventually observe an interference-free single user channel, thus simplify the decoding of each user. The impact of channel feedback errors on the system performance and the upper bounds of several schemes for performance comparison were investigated. The simulation results show that the proposed precoding for multiuser spatial multiplexing system obtains almost the same performance as the single user precoding system.
Performance Analysis of Precoding Based on Massive MIMO System
Directory of Open Access Journals (Sweden)
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.
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...
Directory of Open Access Journals (Sweden)
Manuel Briceño Jauregui
1969-05-01
Full Text Available El instinto de imitación ha encontrado siempre su expresión en todos los pueblos. De todas las formas de entretenimiento, el mimo es a la vez la más primitiva y estable. En el mundo antiguo existen juglares, acróbatas, diversiones públicas de todas clases realizadas por hombres y mujeres, que prueban sus múltiples habilidades en las plazas de mercado, en las calles, con motivo de festividades públicas, o en los banquetes privados -como cuenta Jenofonte en el Simposio para entretención de los huéspedes a la mesa.
Cosmological perturbations in massive bigravity
Energy Technology Data Exchange (ETDEWEB)
Lagos, Macarena; Ferreira, Pedro G., E-mail: m.lagos13@imperial.ac.uk, E-mail: p.ferreira1@physics.ox.ac.uk [Astrophysics, University of Oxford, DWB, Keble road, Oxford OX1 3RH (United Kingdom)
2014-12-01
We present a comprehensive analysis of classical scalar, vector and tensor cosmological perturbations in ghost-free massive bigravity. In particular, we find the full evolution equations and analytical solutions in a wide range of regimes. We show that there are viable cosmological backgrounds but, as has been found in the literature, these models generally have exponential instabilities in linear perturbation theory. However, it is possible to find stable scalar cosmological perturbations for a very particular choice of parameters. For this stable subclass of models we find that vector and tensor perturbations have growing solutions. We argue that special initial conditions are needed for tensor modes in order to have a viable model.
Space-Constrained Massive MIMO: Hitting the Wall of Favorable Propagation
Masouros, Christos; Matthaiou, Michail
2015-01-01
The recent development of the massive multiple-input multiple-output (MIMO) paradigm, has been extensively based on the pursuit of favorable propagation: in the asymptotic limit, the channel vectors become nearly orthogonal and interuser interference tends to zero [1]. In this context, previous studieshave considered fixed inter-antenna distance, which implies an increasing array aperture as the number of elements increases. Here, we focus on a practical, space-constrained topology, where an ...
Perturbative tests of non-perturbative counting
Dabholkar, Atish; Gomes, João
2010-03-01
We observe that a class of quarter-BPS dyons in mathcal{N} = 4 theories with charge vector ( Q, P) and with nontrivial values of the arithmetic duality invariant I := gcd( Q∧ P) are nonperturbative in one frame but perturbative in another frame. This observation suggests a test of the recently computed nonperturbative partition functions for dyons with nontrivial values of the arithmetic invariant. For all values of I, we show that the nonperturbative counting yields vanishing indexed degeneracy for this class of states everywhere in the moduli space in precise agreement with the perturbative result.
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.
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...
Antenna Design for Diversity and MIMO Application
DEFF Research Database (Denmark)
Ying, Zhinong; Chiu, Chi-Yuk; Zhao, Kun
2015-01-01
Recently, multiple-input multiple-output (MIMO) technology and diversity have attracted much attention both in industry and academia due to high data rate and high spectrum efficiency. By increasing the number of antennas at the transmitter and/or the receiver side of the wireless link, the diver......Recently, multiple-input multiple-output (MIMO) technology and diversity have attracted much attention both in industry and academia due to high data rate and high spectrum efficiency. By increasing the number of antennas at the transmitter and/or the receiver side of the wireless link......, the diversity/MIMO techniques can increase wireless channel capacity without the need of additional power or spectrum in rich scattering environments. However, due to limited space of small mobile devices, the correlation coefficients between MIMO antenna elements are usually very high, and the total...... efficiencies of MIMO elements would be degraded severely due to mutual couplings. In addition, the human body causes high losses on electromagnetic waves. In real applications, the presence of users may result in significant reduction of total antenna efficiencies, and the correlations of MIMO antenna systems...
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.
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...
Deployment and Implementation Strategies for Massive MIMO in 5G
DEFF Research Database (Denmark)
Panzner, Berthold; Zirwas, Wolfgang; Dierks, Stefan
2015-01-01
Massive MIMO has emerged as one technology enabler for the next generation mobile communications 5G. The gains promised by massive MIMO are augured to overcome the capacity crunch in today's mobile networks and to pave the way for the ambitious targets of 5G. The challenge to realize massive MIMO...
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.
Low-SNR Capacity of MIMO Optical Intensity Channels
Chaaban, Anas
2017-09-18
The capacity of the multiple-input multiple-output (MIMO) optical intensity channel is studied, under both average and peak intensity constraints. We focus on low SNR, which can be modeled as the scenario where both constraints proportionally vanish, or where the peak constraint is held constant while the average constraint vanishes. A capacity upper bound is derived, and is shown to be tight at low SNR under both scenarios. The capacity achieving input distribution at low SNR is shown to be a maximally-correlated vector-binary input distribution. Consequently, the low-SNR capacity of the channel is characterized. As a byproduct, it is shown that for a channel with peak intensity constraints only, or with peak intensity constraints and individual (per aperture) average intensity constraints, a simple scheme composed of coded on-off keying, spatial repetition, and maximum-ratio combining is optimal at low SNR.
Tran, Gia Khanh; Dao, Nguyen Dung; Sakaguchi, Kei; Araki, Kiyomichi; Iwai, Hiroshi; Sakata, Tsutomu; Ogawa, Koichi
This paper illustrates a large-scale MIMO propagation channel measurement in a real life environment and evaluates throughput performance of various MIMO schemes in that environment. For that purpose, 4 × 4 MIMO transceivers and a novel spatial scanner are fabricated for wideband MIMO channel measurements in the 5GHz band. A total of more than 50, 000 spatial samples in an area of 150m2, which includes a bedroom, a Japanese room, a hallway, and the living and dining areas, are taken in a real residential home environment. Statistical properties of the propagation channel and throughput performance of various MIMO schemes are evaluated by using measured data. Propagation measurement results show large dynamic channel variations occurring in a real environment in which statistical properties of the channel, such as frequency correlation and spatial correlation are not stationary any more, and become functions of the SNR. Furthermore, evaluation of throughput shows that although MIMO schemes outperform the SISO system in most areas, open loop systems perform badly in the far areas with low SNR. Paying for the cost of CSI or partial CSI at Tx, closed loop and hybrid systems have superior performance compared to other schemes, especially in reasonable SNR areas ranging from 10dB to 30dB. Spatial correlation, which is common in Japanese wooden residences, is also found to be a dominant factor causing throughput degradation of the open loop MIMO schemes.
Explosive hazard detection using MIMO forward-looking ground penetrating radar
Shaw, Darren; Ho, K. C.; Stone, Kevin; Keller, James M.; Popescu, Mihail; Anderson, Derek T.; Luke, Robert H.; Burns, Brian
2015-05-01
This paper proposes a machine learning algorithm for subsurface object detection on multiple-input-multiple-output (MIMO) forward-looking ground-penetrating radar (FLGPR). By detecting hazards using FLGPR, standoff distances of up to tens of meters can be acquired, but this is at the degradation of performance due to high false alarm rates. The proposed system utilizes an anomaly detection prescreener to identify potential object locations. Alarm locations have multiple one-dimensional (ML) spectral features, two-dimensional (2D) spectral features, and log-Gabor statistic features extracted. The ability of these features to reduce the number of false alarms and increase the probability of detection is evaluated for both co-polarizations present in the Akela MIMO array. Classification is performed by a Support Vector Machine (SVM) with lane-based cross-validation for training and testing. Class imbalance and optimized SVM kernel parameters are considered during classifier training.
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.
Limited Feedback Precoding for Massive MIMO
Directory of Open Access Journals (Sweden)
Xin Su
2013-01-01
Full Text Available The large-scale array antenna system with numerous low-power antennas deployed at the base station, also known as massive multiple-input multiple-output (MIMO, can provide a plethora of advantages over the classical array antenna system. Precoding is important to exploit massive MIMO performance, and codebook design is crucial due to the limited feedback channel. In this paper, we propose a new avenue of codebook design based on a Kronecker-type approximation of the array correlation structure for the uniform rectangular antenna array, which is preferable for the antenna deployment of massive MIMO. Although the feedback overhead is quite limited, the codebook design can provide an effective solution to support multiple users in different scenarios. Simulation results demonstrate that our proposed codebook outperforms the previously known codebooks remarkably.
A MIMO FMCW radar approach to HFSWR
Hinz, J. O.; Zölzer, U.
2011-07-01
In this paper we propose one possible approach how to apply the concept of multiple-input multiple-output (MIMO) to monostatic Frequency Modulated Continuous Wave (FMCW) High-Frequency Surface Wave Radar (HFSWR) in a maritime environment. Common tasks for a HFSWR are sea-state monitoring and ship detection, where our focus is on ship detection. A limiting factor in HFSWR is the available bandwidth, which is inversely proportional to the range resolution capability of the radar and typical below 100 kHz. The question is how to extend or combine a conventional single-input multiple-output (SIMO) FMCW phased-array type radar with stretch processing and the colocated MIMO concept to "reuse" the very limited HF radar band resources. Another important question to answer is how MIMO FMCW waveforms can be separated at the receiver.
Matching Parasitic Antenna for Single RF MIMO
DEFF Research Database (Denmark)
Han, Bo; Kalis, A; Nielsen, Rasmus Hjorth
2012-01-01
Single RF MIMO communication emerges a novel low cost communication method which does not consume as much power as the conventional MIMO. The implementation of such single RF MIMO system is done by mapping the weighting factors to the polarizations or the radiation patterns of the antennas....... In order to have such performance, an antenna with rich pattern modes is required by the system, thus the ESPAR antenna is investigated. The critical part on such antenna is parasitic element impedance matching. Unlike the conventional smith-chart matching method which assumes the minimal resistance...... is zero and with goal of 50 ohm or 75 ohm matching, matching on such parasitic antenna will adopt negative value as well. This paper presents a matching network with controllable impedance even to the range of negative values....
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.
Robust adaptive beamforming for MIMO monopulse radar
Rowe, William; Ström, Marie; Li, Jian; Stoica, Petre
2013-05-01
Researchers have recently proposed a widely separated multiple-input multiple-output (MIMO) radar using monopulse angle estimation techniques for target tracking. The widely separated antennas provide improved tracking performance by mitigating complex target radar cross-section fades and angle scintillation. An adaptive array is necessary in this paradigm because the direct path from any transmitter could act as a jammer at a receiver. When the target-free covariance matrix is not available, it is critical to include robustness into the adaptive beamformer weights. This work explores methods of robust adaptive monopulse beamforming techniques for MIMO tracking radar.
Kozma, Gady
2012-01-01
We proved earlier that every measurable function on the circle, after a uniformly small perturbation, can be written as a power series (i.e. a series of exponentials with positive frequencies), which converges almost everywhere. Here we show that this result is basically sharp: the perturbation cannot be made smooth or even H\\"older. We discuss also a similar problem for perturbations with lacunary spectrum.
Energy Technology Data Exchange (ETDEWEB)
Bouchiat, C.; Piketty, C.A. (Lab. de Physique Theorique, Ecole Normale Superieure, 75 - Paris (France))
1991-10-24
We present first a computation of the nuclear anapole moment of thallium by a method developed previously by the authors. Then we perform a detailed analysis of the spin dependent parity violating electron-nucleon potential generated by the hyperfine coupling perturbation upon the pseudoscalar interaction of the electron with the weak charge of the nucleus. This effect is found to be of order {alpha}G{sub F}A{sup 2/3} and represents, depending upon the nucleus, (10-70)% of the anapole moment contribution. In the case of thallium, it compensates almost exactly the contribution associated with the axial hadronic neutral current. This fact, together with other arguments given in the paper, makes thallium a favoured candidate for the anapole moment search provided accurate enough experiments can be performed. (orig.).
Bouchiat, C.; Piketty, C. A.
1991-10-01
We present first a computation of the nuclear anapole moment of thallium by a method developed previously by the authors. Then we perform a detailed analysis of the spin dependent parity violating electron-nucleon potential generated by the hyperfine coupling perturbation upon the pseudoscalar interaction of the electron with the weak charge of the nucleus. This effect is found to be of order αG FA {2}/{3} and represents, depending upon the nucleus, (10-70)% of the anapole moment contribution. In the case of thallium, it compensates almost exactly the contribution associated with the axial hadronic neutral current. This fact, together with other arguments given in the paper, makes thallium a favoured candidate for the anapole moment search provided accurate enough experiments can be performed.
Cross-Layer MIMO Transceiver Optimization for Multimedia Streaming in Interference Networks
Zhang, Fan; Lau, Vincent K. N.
2014-03-01
In this paper, we consider dynamic precoder/decorrelator optimization for multimedia streaming in MIMO interference networks. We propose a truly cross-layer framework in the sense that the optimization objective is the application level performance metrics for multimedia streaming, namely the playback interruption and buffer overflow probabilities. The optimization variables are the MIMO precoders/decorrelators at the transmitters and the receivers, which are adaptive to both the instantaneous channel condition and the playback queue length. The problem is a challenging multi-dimensional stochastic optimization problem and brute-force solution has exponential complexity. By exploiting the underlying timescale separation and special structure in the problem, we derive a closed-form approximation of the value function based on continuous time perturbation. Using this approximation, we propose a low complexity dynamic MIMO precoder/decorrelator control algorithm by solving an equivalent weighted MMSE problem. We also establish the technical conditions for asymptotic optimality of the low complexity control algorithm. Finally, the proposed scheme is compared with various baselines through simulations and it is shown that significant performance gain can be achieved.
Applications of Cosmological Perturbation Theory
Christopherson, Adam J
2011-01-01
Cosmological perturbation theory is crucial for our understanding of the universe. The linear theory has been well understood for some time, however developing and applying the theory beyond linear order is currently at the forefront of research in theoretical cosmology. This thesis studies the applications of perturbation theory to cosmology and, specifically, to the early universe. Starting with some background material introducing the well-tested 'standard model' of cosmology, we move on to develop the formalism for perturbation theory up to second order giving evolution equations for all types of scalar, vector and tensor perturbations, both in gauge dependent and gauge invariant form. We then move on to the main result of the thesis, showing that, at second order in perturbation theory, vorticity is sourced by a coupling term quadratic in energy density and entropy perturbations. This source term implies a qualitative difference to linear order. Thus, while at linear order vorticity decays with the expan...
Towards Very Large Aperture Massive MIMO
DEFF Research Database (Denmark)
Oliveras Martínez, Àlex; De Carvalho, Elisabeth; Nielsen, Jesper Ødum
2014-01-01
on the impact of the array aperture which is the main limiting factor in the degrees of freedom available in the multiple antenna channel. We find that performance is improved as the aperture increases, with an impact mostly visible in crowded scenarios where the users are closely spaced. We also test MIMO...
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.
A Design of Double Broadband MIMO Antenna
Directory of Open Access Journals (Sweden)
Yanfeng Geng
2015-01-01
Full Text Available The MIMO antenna applied to LTE mobile system should be miniaturization and can work in the current communication frequency band; isolation between each antenna unit also should be good so as to reduce loss of radio wave energy and improve the antenna performance of the MIMO system. This paper puts forward the design scheme of a broadband MIMO double antenna. And the design of antenna unit and debugging and related technical measures, such as bending antenna bracket, are both presented; the integration design of high isolation of ultra broadband MIMO antenna is realized on the plate with the volume of 100 × 52 × 0.8 mm3; antenna working bands are 698 MHz~960 MHz and 1710 MHz~2700 MHz; in the whole spectrum, the 10 dB of port isolation can be basically achieved; in low frequency band, the isolation degree of antenna port can reach 12 dB.
Orthogonal antenna architecture for MIMO handsets
DEFF Research Database (Denmark)
Tatomirescu, Alexandru; Alrabadi, Osama; Pedersen, Gert Frølund
2012-01-01
The paper presents a method for decorrelating the antenna elements of a MIMO system in a compact handheld terminal at low bands. The architecture of the antenna system induces orthogonal currents over the closely spaced antennas resulting in a correlation free system. Nevertheless, due to the small...
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...
A Perspective on the MIMO Wiretap Channel
Oggier, Frederique
2015-10-01
A wiretap channel is a communication channel between a transmitter Alice and a legitimate receiver Bob, in the presence of an eavesdropper Eve. The goal of communication is to achieve reliability between Alice and Bob, but also confidentiality despite Eve’s presence. Wiretap channels are declined in all kinds of flavors, depending on the underlying channels used by the three players: discrete memoryless channels, additive Gaussian noise channels, or fading channels, to name a few. In this survey, we focus on the case where the three players use multiple-antenna channels with Gaussian noise to communicate. After summarizing known results for multiple-input–multiple-output (MIMO) channels, both in terms of achievable reliable data rate (capacity) and code design, we introduce the MIMO wiretap channel. We then state the MIMO wiretap capacity, summarize the idea of the proof(s) behind this result, and comment on the insights given by the proofs on the physical meaning of the secrecy capacity. We finally discuss design criteria for MIMO wiretap codes.
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.
MIMO channel capacity using antenna selection and water pouring
Cuan Cortes, Jose V.; Vargas-Rosales, Cesar; Munoz Rodriguez, David
2014-01-01
Abstract The use of multiple-input multiple-output (MIMO) communication systems has attracted considerable attention due to capacity and performance improvements without increasing the required bandwidth or transmission power. Although MIMO improves the transmission rate and provides reliable communication, these advantages come at a high cost, since multiple radio frequency (RF) chains have to be employed. Therefore, cost-effective implementation of MIMO systems remains as an important chall...
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.
Deployment and Implementation Strategies for Massive MIMO in 5G
Panzner, Berthold; Zirwas, Wolfgang; Dierks, Stefan; Lauridsen, Mads; Mogensen, Preben; Pajukoski, Kari; Miao, Deshan
2015-01-01
Massive MIMO has emerged as one technology enabler for the next generation mobile communications 5G. The gains promised by massive MIMO are augured to overcome the capacity crunch in today's mobile networks and to pave the way for the ambitious targets of 5G. The challenge to realize massive MIMO for 5G is a successful and cost-efficient integration in the overall network concept. This work highlights deployment and implementation strategies for massive MIMO in the context of 5G indoor small ...
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....
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.
A Multiuser MIMO Transmit Beamformer Based on the Statistics of the Signal-to-Leakage Ratio
Directory of Open Access Journals (Sweden)
Chalise BatuK
2009-01-01
Full Text Available A multiuser multiple-input multiple-output (MIMO downlink communication system is analyzed in a Rayleigh fading environment. The approximate closed-form expressions for the probability density function (PDF of the signal-to-leakage ratio (SLR, its average, and the outage probability have been derived in terms of the transmit beamformer weight vector. With the help of some conservative derivations, it has been shown that the transmit beamformer which maximizes the average SLR also minimizes the outage probability of the SLR. Computer simulations are carried out to compare the theoretical and simulation results for the channels whose spatial correlations are modeled with different methods.
MIMO系统的正则块对角化迫零矢量预编码设计%RBD-ZF-VP precoding design for the MIMO system
Institute of Scientific and Technical Information of China (English)
刘国华; 黄洪琼; 吴程
2015-01-01
In order to further reduce the BER of multi-user MIMO (MU-MIMO) downlink transmission system, a RBD-ZF-VP precoding design is proposed. Utilizing the advantages of RBD precoding and VP precoding, the method transforms the RBD precoding matrix into the equivalent channel matrix on the basis of the RBD precoding of the original MIMO system, and then calculates the disturbance vector of VP by utilizing ZF criteria. Finally, a new signal vector will be formed with the disturbance vector added to the original signal vector and then the new signal vector will be processed. The simulation results show that the scheme can be used in multi-user and multi-antenna MIMO transmission system. Compared with the traditional BD precoding and RBD precoding, it improves the performance of the system effectively, which shows that the system has obvious advantages.%为了进一步减少多用户 MIMO （ Multiple-Input Multiple-Output ）下行传输系统的误码率，提出了正则块对角化迫零矢量预编码设计（ RBD-ZF-VP ）。该方法利用正则块对角化预编码（ RBD ）和矢量预编码（ VP ）的优点，在原有 MIMO 系统 RBD 预编码的基础上，将 RBD 预编码的矩阵转变成信道等价矩阵，然后利用迫零（ ZF ）准则求出 VP 的扰动矢量，再将扰动矢量加到原有信号上构成新信号向量，接着对新信号向量进行处理。仿真结果表明，该方案支持多用户多天线 MIMO 传输系统，与传统的块对角化（ BD ）预编码和RBD 预编码相比，有效地提升了系统性能，具有显著的系统误码率性能优势。
Density perturbations with relativistic thermodynamics
Maartens, R
1997-01-01
We investigate cosmological density perturbations in a covariant and gauge- invariant formalism, incorporating relativistic causal thermodynamics to give a self-consistent description. The gradient of density inhomogeneities splits covariantly into a scalar part, a rotational vector part that is determined by the vorticity, and a tensor part that describes the shape. We give the evolution equations for these parts in the general dissipative case. Causal thermodynamics gives evolution equations for viswcous stress and heat flux, which are coupled to the density perturbation equation and to the entropy and temperature perturbation equations. We give the full coupled system in the general dissipative case, and simplify the system in certain cases.
Junction conditions of cosmological perturbations
Tomita, K
2004-01-01
The behavior of perturbations is studied in cosmological models which consist of two different homogeneous regions connected in a spherical shell boundary. The junction conditions for the metric perturbations and the displacements of the shell boundary are analyzed and the surface densities of the perturbed energy and momentum in the shell are derived, using Mukohyama's gauge-invariant formalism and the Israel discontinuity condition. In both homogeneous regions the perturbations of scalar, vector and tensor types are expanded using the 3-dimensional harmonic functions, but the model coupling among them is caused in the shell by the inhomogeneity. By treating the perturbations with odd and even parities separately, it is found, however, that we can have consistent displacements and surface densities for given metric parturbations
Perturbations in Massive Gravity Cosmology
Crisostomi, Marco; Pilo, Luigi
2012-01-01
We study cosmological perturbations for a ghost free massive gravity theory formulated with a dynamical extra metric that is needed to massive deform GR. In this formulation FRW background solutions fall in two branches. In the dynamics of perturbations around the first branch solutions, no extra degree of freedom with respect to GR ispresent at linearized level, likewise what is found in the Stuckelberg formulation of massive gravity where the extra metric isflat and non dynamical. In the first branch, perturbations are probably strongly coupled. On the contrary, for perturbations around the second branch solutions all expected degrees of freedom propagate. While tensor and vector perturbations of the physical metric that couples with matter follow closely the ones of GR, scalars develop an exponential Jeans-like instability on sub-horizon scales. On the other hand, around a de Sitter background there is no instability. We argue that one could get rid of the instabilities by introducing a mirror dark matter ...
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...
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.
Modified MIMO Cube for Enhanced Channel Capacity
Directory of Open Access Journals (Sweden)
Lajos Nagy
2012-01-01
Full Text Available This paper deals with the optimization of MIMO antenna elements' position in modified MIMO cube for getting maximal channel capacity in indoor environment. The dependence of the channel capacity on the antenna orientation was analyzed by simulations. We have also examined the effect of the frequency dependence of the antenna system (in case of conjugate matching and nonconjugate matching for the channel capacity. Based on the simulation results in the created and measured antenna system, the antennas were at a right angle to each other. At the two chosen different structures, we measured the antenna parameters and the channel capacity. In this paper, we present the results of the measurements which clearly confirm our simulations. We will point out the differences between the two antenna structures.
Hybrid Transmission Scheme for MIMO Relay Channels
Directory of Open Access Journals (Sweden)
Guangming Xu
2009-11-01
Full Text Available To improve the achievable rate for the MIMO channels, we propose a hybrid transmission (HT scheme that mixes half-duplex decode-and-forward cooperative relaying transmission （DFRH）with direct transmission (DT. In the HT scheme, the source message is divided into two parts: one is transmitted by DFRH scheme and another is transmitted by DT scheme. Precoding and decoding are considered to convert the original MIMO relay channel into several parallel subchannels so that resource allocation can be easily performed. We focus on the spatial subchannel and power allocation problem. The objective of this problem is to maximize the total achievable rate under the constraints of joint total transmission power. Simulation results show that significant capacity gain can be achieved by the HT scheme compared to the DT scheme and the pure DFRH scheme.
Rateless Coding for MIMO Block Fading Channels
Fan, Yijia; Erkip, Elza; Poor, H Vincent
2008-01-01
In this paper the performance limits and design principles of rateless codes over fading channels are studied. The diversity-multiplexing tradeoff (DMT) is used to analyze the system performance for all possible transmission rates. It is revealed from the analysis that the design of such rateless codes follows the design principle of approximately universal codes for parallel multiple-input multiple-output (MIMO) channels, in which each sub-channel is a MIMO channel. More specifically, it is shown that for a single-input single-output (SISO) channel, the previously developed permutation codes of unit length for parallel channels having rate LR can be transformed directly into rateless codes of length L having multiple rate levels (R, 2R, . . ., LR), to achieve the DMT performance limit.
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...
MIMO Communication Using Single Feed Antenna Arrays
2011-01-01
Multi-input-multi-output (MIMO) communication has emerged as a promis-ing technology for meeting the increasing demand on higher data rates. Thetechnology exploits the spatial resource dimension by sending the datas-treams to different locations in the multi element array (MEA) domain whiledecoding the signals at the receive end based on the signalsŠ unique spatialsignatures. To this end, the MEA is conventionally assumed to be attachedto a number of radios for independently modulating and up...
Small Terminal MIMO Channels with User Interaction
DEFF Research Database (Denmark)
Pedersen, Gert Frølund; Andersen, Jørgen Bach; Eggers, Patrick Claus F.
2007-01-01
This paper gives an overview of results obtained from measurements of different types of multiple-input multiple-output (MIMO) channels. For the indoor case measurements were made at 5.8 GHz from access points (APs) to mobile stations (MSs) at different places in a large open office type room. Th...... an investigation of the potentials for communication between cars approaching as well as in convoy and from inside and outside the car....
Design and Verification of MIMO 2x2 Reference Antennas
DEFF Research Database (Denmark)
Szini, Istvan Janos; Pedersen, Gert Frølund; Estrada, J.;
2012-01-01
The development and initial discussion of a reference MIMO 2×2 antenna concept has been presented in [1]. The reference antenna concept has been created to eliminate the uncertainties linked to the unknown antenna performance of the few LTE MIMO 2×2 reference devices or golden standards currently...
Distributed MIMO Radar for Imaging and High Resolution Target Localization
2012-02-02
SIMO ) radar systems, based on the BLUE, is provided in [20]. The best achievable accuracy for both configurations is derived. MIMO radar systems with...coherent processing are shown to benefit from higher spatial advantage, compared with SIMO systems. The advantage of the MIMO radar scheme over SIMO
Double Ring Antenna Design for MIMO Application in Mobile Terminals
DEFF Research Database (Denmark)
Zhao, Kun; Zhang, Shuai; Ying, Zhinong;
2015-01-01
In this paper, We present a MIMO bezel antenna design composed by a seamless double metal ring structure. The MIMO antenna mainly operates in the loop mode and can cover the majority of globe cellular bands. Good efficiencies (>-4dB) and a low envelope correlation coefficient (<0.5) are achieved,...
Wideband MIMO Channel Capacity Analysis in Multiprobe Anechoic Chamber Setups
DEFF Research Database (Denmark)
Fan, Wei; Kyosti, Pekka; Nielsen, Jesper Ødum
2016-01-01
This paper discusses over the air (OTA) testing for multiple input multiple output (MIMO) capable terminals with emphasis on wideband MIMO channel capacity analysis in a multi-probe anechoic chamber setup. In the literature, the spatial correlation simulation accuracy at the receiver (Rx) side ha...
MIMO Channel Capacity for Handsets in Data Mode Operation
DEFF Research Database (Denmark)
Nielsen, Jesper Ødum; Yanakiev, Boyan; Bonev, Ivan Bonev
2010-01-01
The current paper concerns realistic evaluation of the capacity of the MIMO channel between a BS and handheld device, such as a PDA or smart phone, held in front of the user’s body (data mode). The work is based on measurements of the MIMO channel between two widely separated BSs in a micro...
MIMO Channel Capacity for Handsets in Data Mode Operation
DEFF Research Database (Denmark)
Nielsen, Jesper Ødum; Yanakiev, Boyan; Bonev, Ivan Bonev
2010-01-01
The current paper concerns realistic evaluation of the capacity of the MIMO channel between a BS and handheld device, such as a PDA or smart phone, held in front of the user’s body (data mode). The work is based on measurements of the MIMO channel between two widely separated BSs in a micro-cellular...
Cluster Characteristics in a MIMO Indoor Propagation Environment
DEFF Research Database (Denmark)
Czink, Nicolai; Yin, Xuefeng; Ozcelik, Huseyin
2007-01-01
Essential parameters of physical, propagation-based MIMO channel models are the fading statistics and the directional spread of multipath clusters. In this paper we determine these parameters in the azimuth-of-arrival/azimuth-of-departure (AoA/AoD) domain based on comprehensive indoor MIMO measur...
MIMO Radar Transceiver Design for High Signal-to-Interference-Plus-Noise Ratio
Lipor, John
2013-05-12
Multiple-input multiple-output (MIMO) radar employs orthogonal or partially correlated transmit signals to achieve performance benefits over its phased-array counterpart. It has been shown that MIMO radar can achieve greater spatial resolution, improved signal-to-noise ratio (SNR) and target localization, and greater clutter resolution using space-time adaptive processing (STAP). This thesis explores various methods to improve the signal-to-interference-plus-noise ratio (SINR) via transmit and receive beamforming. In MIMO radar settings, it is often desirable to transmit power only to a given location or set of locations defined by a beampattern. Current methods involve a two- step process of designing the transmit covariance matrix R via iterative solutions and then using R to generate waveforms that fulfill practical constraints such as having a constant-envelope or drawing from a finite alphabet. In this document, a closed- form method to design R is proposed that utilizes the discrete Fourier transform (DFT) coefficients and Toeplitz matrices. The resulting covariance matrix fulfills the practical constraints such as positive semidefiniteness and the uniform elemental power constraint and provides performance similar to that of iterative methods, which require a much greater computation time. Next, a transmit architecture is presented that exploits the orthogonality of frequencies at discrete DFT values to transmit a sum of orthogonal signals from each antenna. The resulting waveforms provide a lower mean-square error than current methods at a much lower computational cost, and a simulated detection scenario demonstrates the performance advantages achieved. It is also desirable to receive signal power only from a given set of directions defined by a beampattern. In a later chapter of this document, the problem of receive beampattern matching is formulated and three solutions to this problem are demonstrated. We show that partitioning the received data vector
Cosmological perturbations in antigravity
Oltean, Marius; Brandenberger, Robert
2014-10-01
We compute the evolution of cosmological perturbations in a recently proposed Weyl-symmetric theory of two scalar fields with oppositely signed conformal couplings to Einstein gravity. It is motivated from the minimal conformal extension of the standard model, such that one of these scalar fields is the Higgs while the other is a new particle, the dilaton, introduced to make the Higgs mass conformally symmetric. At the background level, the theory admits novel geodesically complete cyclic cosmological solutions characterized by a brief period of repulsive gravity, or "antigravity," during each successive transition from a big crunch to a big bang. For simplicity, we consider scalar perturbations in the absence of anisotropies, with potential set to zero and without any radiation. We show that despite the necessarily wrong-signed kinetic term of the dilaton in the full action, these perturbations are neither ghostlike nor tachyonic in the limit of strongly repulsive gravity. On this basis, we argue—pending a future analysis of vector and tensor perturbations—that, with respect to perturbative stability, the cosmological solutions of this theory are viable.
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.
Bistatic MIMO Radar Clutter Suppression by Exploiting the Transmit Angle
Directory of Open Access Journals (Sweden)
Li Jun
2014-04-01
Full Text Available The transmit angle of bistatic radars can be obtained by introducing Multiple-Input Multiple-Output (MIMO radar techniques. The Three-Dimensional (3D clutter spectra, that is, the transmit angle, receive angle, and Doppler frequency, are introduced using the additional angle information to Space-Time Adaptive Processing (STAP. This study reviews the researches on bistatic MIMO-STAP. 3D space-time adaptive processing methods for airborne bistatic side-looking MIMO radars, such as 3D-LCMV, 3D-ACR, 3D-JDL, and 3D projection-based reduced dimensional STAP methods, are discussed. Simulation results show that the proposed methods can improve the small-sample support performance of range-dependent clutter suppression in bistatic side-looking MIMO radar. Finally, the results are summarized and the prospects of bistatic MIMO-STAP are discussed.
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 ...
Cosmological Perturbations: Vorticity, Isocurvature and Magnetic Fields
Christopherson, Adam J
2014-01-01
In this paper I review some recent, interlinked, work undertaken using cosmological perturbation theory -- a powerful technique for modelling inhomogeneities in the Universe. The common theme which underpins these pieces of work is the presence of non-adiabatic pressure, or entropy, perturbations. After a brief introduction covering the standard techniques of describing inhomogeneities in both Newtonian and relativistic cosmology, I discuss the generation of vorticity. As in classical fluid mechanics, vorticity is not present in linearized perturbation theory (unless included as an initial condition). Allowing for entropy perturbations, and working to second order in perturbation theory, I show that vorticity is generated, even in the absence of vector perturbations, by purely scalar perturbations, the source term being quadratic in the gradients of first order energy density and isocurvature, or non-adiabatic pressure perturbations. This generalizes Crocco's theorem to a cosmological setting. I then introduc...
Effective gravitational couplings for cosmological perturbations in generalized Proca theories
De Felice, Antonio; Kase, Ryotaro; Mukohyama, Shinji; Tsujikawa, Shinji; Zhang, Ying-li
2016-01-01
We consider the finite interactions of the generalized Proca theory including the sixth-order Lagrangian and derive the full linear perturbation equations of motion on the flat Friedmann-Lema\\^{i}tre-Robertson-Walker background in the presence of a matter perfect fluid. By construction, the propagating degrees of freedom (besides the matter perfect fluid) are two transverse vector perturbations, one longitudinal scalar, and two tensor polarizations. The Lagrangians associated with intrinsic vector modes neither affect the background equations of motion nor the second-order action of tensor perturbations, but they do give rise to non-trivial modifications to the no-ghost condition of vector perturbations and to the propagation speeds of vector and scalar perturbations. We derive the effective gravitational coupling $G_{\\rm eff}$ with matter density perturbations under a quasi-static approximation on scales deep inside the sound horizon. We find that the existence of intrinsic vector modes allows a possibility ...
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, ...
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.
Bidirectional Fano Algorithm for Lattice Coded MIMO Channels
Al-Quwaiee, Hessa
2013-05-08
Recently, lattices - a mathematical representation of infinite discrete points in the Euclidean space, have become an effective way to describe and analyze communication systems especially system those that can be modeled as linear Gaussian vector channel model. Channel codes based on lattices are preferred due to three facts: lattice codes have simple structure, the code can achieve the limits of the channel, and they can be decoded efficiently using lattice decoders which can be considered as the Closest Lattice Point Search (CLPS). Since the time lattice codes were introduced to Multiple Input Multiple Output (MIMO) channel, Sphere Decoder (SD) has been an efficient way to implement lattice decoders. Sphere decoder offers the optimal performance at the expense of high decoding complexity especially for low signal-to-noise ratios (SNR) and for high- dimensional systems. On the other hand, linear and non-linear receivers, Minimum Mean Square Error (MMSE), and MMSE Decision-Feedback Equalization (DFE), provide the lowest decoding complexity but unfortunately with poor performance. Several studies works have been conducted in the last years to address the problem of designing low complexity decoders for the MIMO channel that can achieve near optimal performance. It was found that sequential decoders using backward tree search can bridge the gap between SD and MMSE. The sequential decoder provides an interesting performance-complexity trade-off using a bias term. Yet, the sequential decoder still suffers from high complexity for mid-to-high SNR values. In this work, we propose a new algorithm for Bidirectional Fano sequential Decoder (BFD) in order to reduce the mid-to-high SNR complexity. Our algorithm consists of first constructing a unidirectional Sequential Decoder based on forward search using the QL decomposition. After that, BFD incorporates two searches, forward and backward, to work simultaneously till they merge and find the closest lattice point to the
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.
A new approach for inversion of large random matrices in massive MIMO systems.
Directory of Open Access Journals (Sweden)
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.
Directory of Open Access Journals (Sweden)
Héctor Carrasco E
2007-12-01
Full Text Available En este trabajo se presentan resultados experimentales de medición de canal y evaluación de capacidad MIMO (Multiple Input Multiple Output de arrays de antenas PIFA (Planar Inverted "F" Antenna compactos en la banda de frecuencia de 2.45 GHz, en entornos interiores ricos en multitrayecto. Se evalúan dos configuraciones básicas de arrays, Lineal y Cuadrada de cuatro antenas PIFA, cuyas características de bajo perfil y grados de libertad de construcción y configuración constituyen ventajas comparativas para aplicaciones con terminales compactos potables. Las mediciones de la matriz de canal MIMO se hacen utilizando un VNA (Vector Network Analyzer controlado vía estándar GPIB (General Purpose Interface Bus. La capacidad MIMO se evalúa estadísticamente para un gran número de medidas del canal, en espacio y frecuencia, con separación de antenas en cada array de 0,1 a 0,8 longitudes de onda, con el objetivo principal de estudiar el efecto del acoplamiento mutuo en la capacidad MIMO. Los resultados de capacidad medida muestran que las configuraciones propuestas más eficientes pueden operar como mínimo hasta separaciones de antenas en el rango de 0,3 a 0,4 longitudes de onda, sin producir gran degradación de capacidad debido al acoplamiento y bloqueo de señal. Este resultado implica separaciones cercanas a 4 cm y, en consecuencia, arrays significativamente compactosThis paper presents experimental results of indoor MIMO wireless channel and channel capacity evaluation for compact PIFA (Planar Inverted "F" Antenna antenna arrays at the 2.45 GHz frequency band. Linear and square array configurations are evaluated using PIFA antenna elements because of its advantages of low profile and flexible configuration design for compact and portable mobile terminals. Measurements are performed using a VNA with GPIB standard for automatic data acquisition. MIMO channel capacity results are calculated from a large amount of data combining uncorrelated
VLSI IMPLEMENTATION OF CHANNEL ESTIMATION FOR MIMO-OFDM TRANSCEIVER
Directory of Open Access Journals (Sweden)
Joseph Gladwin Sekar
2013-01-01
Full Text Available In this study the VLSI architecture for MIMO-OFDM transceiver and the algorithm for the implementation of MMSE detection in MIMO-OFDM system is proposed. The implemented MIMO-OFDM system is capable of transmitting data at high throughput in physical layer and provides optimized hardware resources while achieving the same data rate. The proposed architecture has low latency, high throughput and efficient resource utilization. The result obtained is compared with the MATLAB results for verification. The main aim is to reduce the hardware complexity of the channel estimation.
Practical guide to MIMO radio channel with MATLAB examples
Brown, Tim; De Carvalho, Elizabeth
2012-01-01
This book provides an excellent reference to the MIMO radio channel In this book, the authors introduce the concept of the Multiple Input Multiple Output (MIMO) radio channel, which is an intelligent communication method based upon using multiple antennas. Moreover, the authors provide a summary of the current channel modeling approaches used by industry, academia, and standardisation bodies. Furthermore, the book is structured to allow the reader to easily progress through the chapters in order to gain an understanding of the fundamental and mathematical principles behind MIMO. It al
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.
Ergodic channel capacity of the spatial correlated rayleigh MIMO channel
Institute of Scientific and Technical Information of China (English)
ZHANG Hui-ping; WU Ping; LIU Ai-jun
2007-01-01
The theoretical capacity of the spatial correlated Rayleigh multiple input multiple output (MIMO) channel is an important issue in MIMO technology. In this article, an ergodic channel capacity formula of the spatial correlated rayleigh MIMO channel is provided, which is deduced when two antennas exist at either the transmitter or the receiver. The multi-dimensional least-squares fit algorithm is employed to narrow the difference between the theoretical formula capacity and the practical capacity. Simulation results show that the theoretical capacity approaches the practical one closely.
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.
A novel turbo-MIMO transceiver
Institute of Scientific and Technical Information of China (English)
CHEN Liang; LI JianDong; PANG JiYong
2009-01-01
A novel BLAST transceiver named turbo-like BLAST (TLBLAST) for MIMO communications is proposed,which combines the characteristics of HBLAST and VBLAST with the structure of turbo encoder.The high data rate transmission can be implemented and in each transmitted antenna,different encode schemes can be used to supply different protection levels.The system performance is improved effectively through serially concatenating a soft input soft output (SISO) detector and decoder by iterative process with comparable complexity of VBLAST.Simulation results show that the performance of TLBLAST is better than HBLAST and VBLAST in Rayleigh flat fading channels.
Ortogonalidad y capacidad en sistemas MIMO masivo
Romero Ibáñez, Irene
2014-01-01
La tecnología MIMO constituye un antes y un después en los sistemas de comunicaciones inalámbricas. Esta tecnología ofrece multitud de beneficios que nos acercan a cumplir con los desafíos impuestos por las limitaciones en un canal inalámbrico así como por las restricciones de nuestros recursos o el espacio físico ocupado por las antenas, entre otros. Además de explotar tanto la dimensión temporal como la frecuencial en sistemas inalámbricos convencionales con una única antena, las posibilida...
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.
Capon-based single-snapshot DOA estimation in monostatic MIMO radar
Hassanien, Aboulnasr; Amin, Moeness G.; Zhang, Yimin D.; Ahmad, Fauzia
2015-05-01
We consider the problem of single snapshot direction-of-arrival (DOA) estimation of multiple targets in monostatic multiple-input multiple-output (MIMO) radar. When only a single snapshot is used, the sample covariance matrix of the data becomes non-invertible and, therefore, does not permit application of Capon-based DOA estimation techniques. On the other hand, low-resolution techniques, such as the conventional beamformer, suffer from biased estimation and fail to resolve closely spaced sources. In this paper, we propose a new Capon-based method for DOA estimation in MIMO radar using a single radar pulse. Assuming that the angular locations of the sources are known a priori to be located within a certain spatial sector, we employ multiple transmit beams to focus the transmit energy of multiple orthogonal waveforms within the desired sector. The transmit weight vectors are carefully designed such that they have the same transmit power distribution pattern. As compared to the standard MIMO radar, the proposed approach enables transmitting an arbitrary number of orthogonal waveforms. By using matched-filtering at the receiver, the data associated with each beam is extracted yielding a virtual data snapshot. The total number of virtual snapshots is equal to the number of transmit beams. By choosing the number of transmit beams to be larger than the number of receive elements, it becomes possible to form a full-rank sample covariance matrix. The Capon beamformer is then applied to estimate the DOAs of the targets of interest. The proposed method is shown to have improved DOA estimation performance as compared to conventional single-snapshot DOA estimation methods.
Directory of Open Access Journals (Sweden)
Tao Chen
2014-01-01
Full Text Available We address the problem of a new joint Doppler frequency shift (DFS and direction of arrival (DOA estimation for colocated TDM-MIMO radar that is a novel technology applied to autocruise and safety driving system in recent years. The signal model of colocated TDM-MIMO radar with few transmitter or receiver channels is depicted and “time varying steering vector” model is proved. Inspired by sparse representations theory, we present a new processing scheme for joint DFS and DOA estimation based on the new input signal model of colocated TDM-MIMO radar. An ultracomplete redundancy dictionary for angle-frequency space is founded in order to complete sparse representations of the input signal. The SVD-SR algorithm which stands for joint estimation based on sparse representations using SVD decomposition with OMP algorithm and the improved M-FOCUSS algorithm which combines the classical M-FOCUSS with joint sparse recovery spectrum are applied to the new signal model’s calculation to solve the multiple measurement vectors (MMV problem. The improved M-FOCUSS algorithm can work more robust than SVD-SR and JS-SR algorithms in the aspects of coherent signals resolution and estimation accuracy. Finally, simulation experiments have shown that the proposed algorithms and schemes are feasible and can be further applied to practical application.
Directory of Open Access Journals (Sweden)
Sabitha Gauni
2014-03-01
Full Text Available In the field of Wireless Communication, there is always a demand for reliability, improved range and speed. Many wireless networks such as OFDM, CDMA2000, WCDMA etc., provide a solution to this problem when incorporated with Multiple input- multiple output (MIMO technology. Due to the complexity in signal processing, MIMO is highly expensive in terms of area consumption. In this paper, a method of MIMO receiver design is proposed to reduce the area consumed by the processing elements involved in complex signal processing. In this paper, a solution for area reduction in the Multiple input multiple output(MIMO Maximum Likelihood Receiver(MLE using Sorted QR Decomposition and Unitary transformation method is analyzed. It provides unified approach and also reduces ISI and provides better performance at low cost. The receiver pre-processor architecture based on Minimum Mean Square Error (MMSE is compared while using Iterative SQRD and Unitary transformation method for vectoring. Unitary transformations are transformations of the matrices which maintain the Hermitian nature of the matrix, and the multiplication and addition relationship between the operators. This helps to reduce the computational complexity significantly. The dynamic range of all variables is tightly bound and the algorithm is well suited for fixed point arithmetic.
Institute of Scientific and Technical Information of China (English)
呙涛; 胡国荣
2014-01-01
In order to enhance the ability of multiple-input multiple-output(MIMO) power line communication system against the impulsive noise,a scheme is proposed to mitigating the impulsive noise impact on MIMO power line communications based on sparse Bayesian learning and correlation of impulsive noise on power lines.Under this scheme,all of the subcarriers are used to jointly estimate the impulsive noise and the signals on the available subcarriers.There is no need for information of training impulsive noise.The Bivariate Middleton Class A model is used in the case study to fit the impulsive noise,and the results show that the performance of the proposed scheme against the impulsive noise is better than the multiple measurement vector sparse Bayesion learning (MSBL) scheme using null subcarriers with an improvement of 1 1 dB signal to noise ratio (SNR).%为提高多输入多输出(MIMO)电力线通信系统对抗脉冲噪声的能力，基于稀疏贝叶斯学习的理论，利用脉冲噪声在电力线上的相关性，提出了一种消除 MIMO 电力线脉冲噪声的方案。方案使用全部子载波来联合估计脉冲噪声和可用子载波上的信号，无需训练脉冲噪声的统计信息。仿真中脉冲噪声拟合采用 Bivariate Middleton Class A 模型，结果表明该方案抗脉冲噪声性能比只使用空子载波的多观测向量稀疏贝叶斯学习(MSBL)方案提升了11 dB。
Transmission Strategies in MIMO Ad Hoc Networks
Directory of Open Access Journals (Sweden)
Fakih Khalil
2009-01-01
Full Text Available Abstract Precoding problem in multiple-input multiple-output (MIMO ad hoc networks is addressed in this work. Firstly, we consider the problem of maximizing the system mutual information under a power constraint. In this context, we give a brief overview of the nonlinear optimization methods, and systematically we compare their performances. Then, we propose a fast and distributed algorithm based on the quasi-Newton methods to give a lower bound of the system capacity of MIMO ad hoc networks. Our proposed algorithm solves the maximization problem while diminishing the amount of information in the feedback links needed in the cooperative optimization. Secondly, we propose a different problem formulation, which consists in minimizing the total transmit power under a quality of signal constraint. This novel problem design is motivated since the packets are captured in ad hoc networks based on their signal-to-interference-plus-noise ratio (SINR values. We convert the proposed formulation into semidefinite optimization problem, which can be solved numerically using interior point methods. Finally, an extensive set of simulations validates the proposed algorithms.
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.
A Switched Diversity Scheme for Massive MIMO Systems
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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.
MIMO Technologies in 3GPP LTE and LTE-Advanced
Directory of Open Access Journals (Sweden)
Juho Lee
2009-01-01
Full Text Available 3rd Generation Partnership Project (3GPP has recently completed the specification of the Long Term Evolution (LTE standard. Majority of the world's operators and vendors are already committed to LTE deployments and developments, making LTE the market leader in the upcoming evolution to 4G wireless communication systems. Multiple input multiple output (MIMO technologies introduced in LTE such as spatial multiplexing, transmit diversity, and beamforming are key components for providing higher peak rate at a better system efficiency, which are essential for supporting future broadband data service over wireless links. Further extension of LTE MIMO technologies is being studied under the 3GPP study item “LTE-Advanced” to meet the requirement of IMT-Advanced set by International Telecommunication Union Radiocommunication Sector (ITU-R. In this paper, we introduce various MIMO technologies employed in LTE and provide a brief overview on the MIMO technologies currently discussed in the LTE-Advanced forum.
On detection performance of MIMO radar for Rician target
Institute of Scientific and Technical Information of China (English)
TANG Jun; WU Yong; PENG YingNing; WANG XiuTan
2009-01-01
By using spatial dlversity, multiple-input-multiple-output (MIMO) radar can improve detection performance for fluctuating targets. In this paper, we propose a spatial fluctuation target model for MIMO radar, where targets are classified as non-fluctuating target, Rayleigh target and Rician target. Based on Stein's lemma, we use relative entropy to study detection performance of optimum detector for Riclan target. It is found that in low signal noise ratio (SNR) region, the performance improvement of MIMO radar for detecting Rician target depends on array gain, which is related to the number of receivers. In high SNR region, the improvement of performance depends on diversity gain, which is related to the product of the number of receivers and the number of transmitters. The conclusions of this paper are Important for designing MIMO radar system.
Channel Estimation Techniques in MIMO-OFDM LTE Systems
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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.
Interference Alignment for Partially Connected MIMO Cellular Networks
Ruan, Liangzhong
2012-01-01
In this paper, we propose an iterative interference alignment (IA) algorithm for MIMO cellular networks with partial connectivity, which is induced by heterogeneous path losses and spatial correlation. Such systems impose several key technical challenges in the IA algorithm design, namely the overlapping between the direct and interfering links due to the MIMO cellular topology as well as how to exploit the partial connectivity. We shall address these challenges and propose a three stage IA algorithm. As illustration, we analyze the achievable degree of freedom (DoF) of the proposed algorithm for a symmetric partially connected MIMO cellular network. We show that there is significant DoF gain compared with conventional IA algorithms due to partial connectivity. The derived DoF bound is also backward compatible with that achieved on fully connected K-pair MIMO interference channels.
Distributed MIMO-ISAR Sub-image Fusion Method
Directory of Open Access Journals (Sweden)
Gu Wenkun
2017-02-01
Full Text Available The fast fluctuation associated with maneuvering a target’s radar cross-section often affects the imaging performance stability of traditional monostatic Inverse Synthetic Aperture Radar (ISAR. To address this problem, in this study, we propose an imaging method based on the fusion of sub-images of frequencydiversity-distributed multiple Input-Multiple Output-Inverse Synthetic Aperture Radar (MIMO-ISAR. First, we establish the analytic expression of a two-dimensional ISAR sub-image acquired by different channels of distributed MIMO-ISAR. Then, we derive the distance and azimuth distortion factors of the image acquired by the different channels. By compensating for the distortion of the ISAR image, we ultimately realize distributed MIMO-ISAR fusion imaging. Simulations verify the validity of this imaging method using distributed MIMO-ISAR.
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....
MIMO Technologies in 3GPP LTE and LTE-Advanced
Directory of Open Access Journals (Sweden)
Zhang Jianzhong(Charlie
2009-01-01
Full Text Available Abstract 3rd Generation Partnership Project (3GPP has recently completed the specification of the Long Term Evolution (LTE standard. Majority of the world's operators and vendors are already committed to LTE deployments and developments, making LTE the market leader in the upcoming evolution to 4G wireless communication systems. Multiple input multiple output (MIMO technologies introduced in LTE such as spatial multiplexing, transmit diversity, and beamforming are key components for providing higher peak rate at a better system efficiency, which are essential for supporting future broadband data service over wireless links. Further extension of LTE MIMO technologies is being studied under the 3GPP study item "LTE-Advanced" to meet the requirement of IMT-Advanced set by International Telecommunication Union Radiocommunication Sector (ITU-R. In this paper, we introduce various MIMO technologies employed in LTE and provide a brief overview on the MIMO technologies currently discussed in the LTE-Advanced forum.
CSSF MIMO RADAR: Low-Complexity Compressive Sensing Based MIMO Radar That Uses Step Frequency
Yu, Yao; Poor, H Vincent
2011-01-01
A new approach is proposed, namely CSSF MIMO radar, which applies the technique of step frequency (SF) to compressive sensing (CS) based multi-input multi-output (MIMO) radar. The proposed approach enables high resolution range, angle and Doppler estimation, while transmitting narrowband pulses. The problem of joint angle-Doppler-range estimation is first formulated to fit the CS framework, i.e., as an L1 optimization problem. Direct solution of this problem entails high complexity as it employs a basis matrix whose construction requires discretization of the angle-Doppler-range space. Since high resolution requires fine space discretization, the complexity of joint range, angle and Doppler estimation can be prohibitively high. For the case of slowly moving targets, a technique is proposed that achieves significant complexity reduction by successively estimating angle-range and Doppler in a decoupled fashion and by employing initial estimates obtained via matched filtering to further reduce the space that nee...
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...
An Achievable Rate for the MIMO Individual Channel
Lomnitz, Yuval
2010-01-01
We consider the problem of communicating over a multiple-input multiple-output (MIMO) real valued channel for which no mathematical model is specified, and achievable rates are given as a function of the channel input and output sequences known a-posteriori. This paper extends previous results regarding individual channels by presenting a rate function for the MIMO individual channel, and showing its achievability in a fixed transmission rate communication scenario.
Emulating Spatial Characteristics of MIMO Channels for OTA Testing
DEFF Research Database (Denmark)
Fan, Wei; Carreño, Xavier; Sun, Fan;
2013-01-01
This paper discusses over the air (OTA) testing for multiple input multiple output (MIMO) capable terminals with emphasis on channel spatial characteristics emulation. A novel technique to obtain optimum power weights for the OTA probes based on convex optimization is proposed. The proposed...... performance compared with existing techniques in the literature. This improvement is further demonstrated by measurement results in a practical MIMO OTA setup....
MIMO-OC Scheme to Suppress Co-channel Interference
Zhang, Wei Jiong; Zhou, Xi Lang; Jin, Rong Hong
In this letter, we present a multiple-input multiple-output (MIMO) optimal combining (OC) scheme based on alternate iteration. With the channel state information (CSI) of co-channel interferers (CCIs), this algorithm can be used in flat fading and frequency selective channels to suppress CCIs. Compared with the optimal transceiver of MIMO maximal ratio combining (MRC) systems, results of simulation show that this scheme improves the uplink transmission performance significantly.
Analysis on some factors affecting MIMO in tunnel
Zheng, Hong-dang; Nie, Xiao-Yan; Xu, Zhao
2009-07-01
Based on the 3D-GBSB (three-dimensional Geometrically Based Single-Bounce) model and MIMO channel capacity function, by geometric analysis, it is analyzed that transceiver antenna arrays, antenna spacing, antenna array angle, SNR and Rician K-factor and so on impact on the frequency-nonselective fading MIMO channel capacity. Monte Carlo method can be applied to stimulate the wireless fading channel and demonstrate Cumulative Distribution Function of above.
Channel Statistics for MIMO Handsets in Data Mode
DEFF Research Database (Denmark)
Nielsen, Jesper Ødum; Yanakiev, Boyan; Barrio, Samantha Caporal Del;
2014-01-01
The presented work is based on a large dual- band, dual-base outdoor-to-indoor multiple-input multiple- output (MIMO) channel measurement campaign, involving ten different realistic MIMO handsets, held in data mode by eight test users. Various different use cases (UCs) are measured. Statistics on...... on the channel capacity, mean effective gain (MEG), branch power ratio (BPR), and correlation coefficients between Rx, Tx, and cross-link channels are presented....
Design of Massive-MIMO-NOMA With Limited Feedback
Ding, Zhiguo; Poor, H. Vincent
2016-05-01
In this letter, a low-feedback non-orthogonal multiple access (NOMA) scheme using massive multiple-input multiple-output (MIMO) transmission is proposed. In particular, the proposed scheme can decompose a massive-MIMO-NOMA system into multiple separated single-input single-output NOMA channels, and analytical results are developed to evaluate the performance of the proposed scheme for two scenarios, with perfect user ordering and with one-bit feedback, respectively.
Parametric Adaptive Matched Filter for Multistatic MIMO Radar (Preprint)
2016-11-04
SUPPLEMENTARY NOTES Journal article submitted for publication to the IEEE Transactions on Aerospace and Electronic Systems. The U.S. Government is joint...Prescribed by ANSI Std. Z39-18 1 Parametric Adaptive Matched Filter for Multistatic MIMO Radar Tariq Qureshi Member, IEEE , Muralidhar Rangaswamy, Fellow... IEEE , and Kristine Bell, Fellow, IEEE Abstract A fully disrtibuted MIMO radar system can be treated in terms of all bistatic pairs. If a bistatic
Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar
2015-01-01
The two-dimensional angular resolution limit (ARL) of elevation and azimuth for MIMO radar with ultrawideband (UWB) noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs) of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach i...
Unified Stochastic Geometry Model for MIMO Cellular Networks with Retransmissions
Afify, Laila H.
2016-10-11
This paper presents a unified mathematical paradigm, based on stochastic geometry, for downlink cellular networks with multiple-input-multiple-output (MIMO) base stations (BSs). The developed paradigm accounts for signal retransmission upon decoding errors, in which the temporal correlation among the signal-to-interference-plus-noise-ratio (SINR) of the original and retransmitted signals is captured. In addition to modeling the effect of retransmission on the network performance, the developed mathematical model presents twofold analysis unification for MIMO cellular networks literature. First, it integrates the tangible decoding error probability and the abstracted (i.e., modulation scheme and receiver type agnostic) outage probability analysis, which are largely disjoint in the literature. Second, it unifies the analysis for different MIMO configurations. The unified MIMO analysis is achieved by abstracting unnecessary information conveyed within the interfering signals by Gaussian signaling approximation along with an equivalent SISO representation for the per-data stream SINR in MIMO cellular networks. We show that the proposed unification simplifies the analysis without sacrificing the model accuracy. To this end, we discuss the diversity-multiplexing tradeoff imposed by different MIMO schemes and shed light on the diversity loss due to the temporal correlation among the SINRs of the original and retransmitted signals. Finally, several design insights are highlighted.
DESIGN & IMPLEMENTATION OF RECONFIGURABLE FRONT END FOR MIMO-OFDM
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VEENA M.B.
2011-02-01
Full Text Available This paper focuses on design, implement and optimization of digital front end module of Multiple Input Multiple Output (MIMO-Orthogonal Frequency Division Multiplexing (OFDM system on FPGA employing Alamouti Technique (Space Time Block coding. MIMO-OFDM can very effectively be used to achieve higher data rate’s and higher reliability and this is going to be the Key for 4G Technology. MIMO -OFDM designed in this work consists of Input/Output Memory, 16 QAM Modulator, MIMO Encoder (Space Time Encoder, Wireless Channel Model, MIMO Decoder Space Time Decoder and 16 QAM Demodulator. This paper has resulted in the development of a hardware prototype of a MIMO Transmitter, Receiver and channel, which is implemented on a Spartan-3 FPGA board. As the number format adopted is floating point,there was a need to develop a separate function which will show the equivalent real numbers for the corresponding floating point number. This made the task of debugging a lot easier. Test benches for individual model were developed and tested it for its correct functionality. The functional simulation was carried out for the entire design. The entire design was mapped on to FPGA. The results were compared with the MATLAB results and were found to be the same.
Spatially Common Sparsity Based Adaptive Channel Estimation and Feedback for FDD Massive MIMO
Gao, Zhen; Dai, Linglong; Wang, Zhaocheng; Chen, Sheng
2015-12-01
This paper proposes a spatially common sparsity based adaptive channel estimation and feedback scheme for frequency division duplex based massive multi-input multi-output (MIMO) systems, which adapts training overhead and pilot design to reliably estimate and feed back the downlink channel state information (CSI) with significantly reduced overhead. Specifically, a non-orthogonal downlink pilot design is first proposed, which is very different from standard orthogonal pilots. By exploiting the spatially common sparsity of massive MIMO channels, a compressive sensing (CS) based adaptive CSI acquisition scheme is proposed, where the consumed time slot overhead only adaptively depends on the sparsity level of the channels. Additionally, a distributed sparsity adaptive matching pursuit algorithm is proposed to jointly estimate the channels of multiple subcarriers. Furthermore, by exploiting the temporal channel correlation, a closed-loop channel tracking scheme is provided, which adaptively designs the non-orthogonal pilot according to the previous channel estimation to achieve an enhanced CSI acquisition. Finally, we generalize the results of the multiple-measurement-vectors case in CS and derive the Cramer-Rao lower bound of the proposed scheme, which enlightens us to design the non-orthogonal pilot signals for the improved performance. Simulation results demonstrate that the proposed scheme outperforms its counterparts, and it is capable of approaching the performance bound.
Directory of Open Access Journals (Sweden)
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.
Directory of Open Access Journals (Sweden)
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.
Efficient Closed-Loop Schemes for MIMO-OFDM-Based WLANs
Zheng, Xiayu; Jiang, Yi; Li, Jian
2006-12-01
The single-input single-output (SISO) orthogonal frequency-division multiplexing (OFDM) systems for wireless local area networks (WLAN) defined by the IEEE 802.11a standard can support data rates up to 54 Mbps. In this paper, we consider deploying two transmit and two receive antennas to increase the data rate up to 108 Mbps. Applying our recent multiple-input multiple-output (MIMO) transceiver designs, that is, the geometric mean decomposition (GMD) and the uniform channel decomposition (UCD) schemes, we propose simple and efficient closed-loop MIMO-OFDM designs for much improved performance, compared to the standard singular value decomposition (SVD) based schemes as well as the open-loop V-BLAST (vertical Bell Labs layered space-time) based counterparts. In the explicit feedback mode, precoder feedback is needed for the proposed schemes. We show that the overhead of feedback can be made very moderate by using a vector quantization method. In the time-division duplex (TDD) mode where the channel reciprocity is exploited, our schemes turn out to be robust against the mismatch between the uplink and downlink channels. The advantages of our schemes are demonstrated via extensive numerical examples.
Efficient Closed-Loop Schemes for MIMO-OFDM-Based WLANs
Directory of Open Access Journals (Sweden)
Jiang Yi
2006-01-01
Full Text Available The single-input single-output (SISO orthogonal frequency-division multiplexing (OFDM systems for wireless local area networks (WLAN defined by the IEEE 802.11a standard can support data rates up to 54 Mbps. In this paper, we consider deploying two transmit and two receive antennas to increase the data rate up to 108 Mbps. Applying our recent multiple-input multiple-output (MIMO transceiver designs, that is, the geometric mean decomposition (GMD and the uniform channel decomposition (UCD schemes, we propose simple and efficient closed-loop MIMO-OFDM designs for much improved performance, compared to the standard singular value decomposition (SVD based schemes as well as the open-loop V-BLAST (vertical Bell Labs layered space-time based counterparts. In the explicit feedback mode, precoder feedback is needed for the proposed schemes. We show that the overhead of feedback can be made very moderate by using a vector quantization method. In the time-division duplex (TDD mode where the channel reciprocity is exploited, our schemes turn out to be robust against the mismatch between the uplink and downlink channels. The advantages of our schemes are demonstrated via extensive numerical examples.
Mimo Lms-Armax Identification of Vibrating STRUCTURES—PART i: the Method
Fassois, S. D.
2001-07-01
A comprehensive linear multi stage autoregressive moving average with exogenous excitation (LMS-ARMAX) method for effective multiple-input multiple-output (MIMO) structural dynamics identification in the presence of noise is introduced. The method consists of (a) a vector ARMAX representation of an appropriate form, (b) effective LMS parameter estimation, (c) statistical order selection/validation, and (d) a digital dispersion analysis (DA) methodology for effective modal characterization. The LMS-ARMAX method overcomes many of the difficulties that had rendered MIMO ARMAX identification difficult in the past, featuring modest computational complexity, high accuracy, guaranteed algorithmic and model stability, and thus applicability to higher-dimensional problems and lightly damped structures, accurate modal parameter extraction, and effective distinction of structural from 'extraneous' modes. A critical assessment of the LMS-ARMAX method under various noise conditions, as well as comparisons with a simpler ARX version and the ERA (Eigensystem Realization Algorithm), are undertaken based upon experimental vibration data obtained from a scale aircraft skeleton structure. The paper is divided into two parts: The LMS-ARMAX method is presented in the first, and its critical assessment and comparisons in the second.
KAPASITAS KANAL DAN BIT ERROR RATE SISTEM D-MIMO DALAM VARIASI SPASIAL DAERAH CAKUPAN
Directory of Open Access Journals (Sweden)
Nyoman Gunantara
2009-05-01
Full Text Available Kemajuan teknologi komunikasi, dikembangkan sistem D-MIMO (Distributed MIMO yang sebelumnya telah digunakan sistem C-MIMO (Conventional co-located MIMO. Sistem C-MIMO menyebabkan penggunaan spektrummenjadi efisien, daya pancar berkurang, dan kapasitas kanal meningkat.Dengan sistem D-MIMO jarak antara pemancar dan penerima dapat diperpendek, macrodiversity dan adanya daerah cakupan layanan. Pada tulisan ini akan diteliti tentang kapasitas kanal dan Bit Error Rate (BER pada variasi spasial daerah cakupan. Penelitian tersebut dilakukan pada kapasitas kanal teoritis dan BER dengan teknik waterfilling.Kapasitas kanal dan kinerja BER pada sistem D-MIMO pada variasi spasial daerah cakupan tergantung dari konfigurasi sistem D-MIMO. Lokasi penerima yang dekat port antena pemancar mempunyai kapasitas kanal yanglebih besar tetapi memiliki kinerja BER yang lebih buruk.
Roche, John
1997-01-01
Suggests an approach to teaching vectors that promotes active learning through challenging questions addressed to the class, as opposed to subtle explanations. Promotes introducing vector graphics with concrete examples, beginning with an explanation of the displacement vector. Also discusses artificial vectors, vector algebra, and unit vectors.…
REVIEW OF THE PILOT CONTAMINATION PROBLEM FOR MASSIVE MIMO AND POSSIBLE SOLUTION
Atul Kumar Mishra*, Prof. Saurabh Gaur
2016-01-01
With the increasing demands of data communication speed for different type of data transmission, many revolutions occur with time in wireless communication system. The use of MIMO for wireless data transmission has proven itself for enhancing the capacity of data transmission. The mobile network based on the cell structure also uses the MIMO techniques. Further research in the field of massive MIMO has started for faithful data transmission. The enhancement by massive MIMO encounters many pro...
Body Loss Study of Beamforming Mode in LTE MIMO Mobile Terminals
DEFF Research Database (Denmark)
Zhang, Shuai; Zhao, Kun; Ying, Zhinong;
2015-01-01
, the parallel GF MIMO antenna type exhibits the best beamforming performance in the four MIMO antenna types. In order to verify the simulations, envelope correlation coefficients of two MIMO antenna prototypes are measured. All the measured results agree well with the simulated....
Body-insensitive Multi-Mode MIMO Terminal Antenna of Double-Ring Structure
DEFF Research Database (Denmark)
Zhao, Kun; Zhang, Shuai; Ishimiya, Katsunori;
2015-01-01
In this paper, we propose a novel multimode multi-input multi-output (MIMO) antenna system composed of a dual-element MIMO cellular antenna and dual-element MIMO Wi-Fi antenna for mobile terminal applications. The antenna system has a double-ring structure and can be integrated with the metal fra...
Signal Waveforms and Range/Angle Coupling in Coherent Colocated MIMO Radar
2014-10-09
Signal Waveforms and Range/Angle Coupling in Coherent Colocated MIMO Radar Olivier Rabaste, Laurent Savy, Mathieu Cattenoz ONERA , The French...tests with a real MIMO radar: HYCAM. A. The HYCAM platform A multifunction MIMO radar - named HYCAM - has been designed and build by ONERA . The
Opportunistic Interference Alignment in MIMO Interference Channels
Perlaza, Samir Medina; Lasaulce, Samson; Chaufray, Jean Marie
2008-01-01
We present two interference alignment techniques such that an opportunistic point-to-point multiple input multiple output (MIMO) link can reuse, without generating any additional interference, the same frequency band of a similar pre-existing primary link. In this scenario, we exploit the fact that under power constraints, although each radio maximizes independently its rate by water-filling on their channel transfer matrix singular values, frequently, not all of them are used. Therefore, by aligning the interference of the opportunistic radio it is possible to transmit at a significant rate while insuring zero-interference on the pre-existing link. We propose a linear pre-coder for a perfect interference alignment and a power allocation scheme which maximizes the individual data rate of the secondary link. Our numerical results show that significant data rates are achieved even for a reduced number of antennas.
Cooperative Feedback for MIMO Interference Channels
Huang, Kaibin
2010-01-01
Multi-antenna precoding effectively mitigates the interference in wireless networks. However, the precoding efficiency can be significantly degraded by the overhead due to the required feedback of channel state information (CSI). This paper addresses such an issue by proposing a systematic method of designing precoders for the two-user multiple-input-multiple-output (MIMO) interference channels based on finite-rate CSI feedback from receivers to their interferers, called cooperative feedback. Specifically, each precoder is decomposed into inner and outer precoders for nulling interference and improving the data link array gain, respectively. The inner precoders are further designed to suppress residual interference resulting from finite-rate cooperative feedback. To regulate residual interference due to precoder quantization, additional scalar cooperative feedback signals are designed to control transmitters' power using different criteria including applying interference margins, maximizing sum throughput, an...
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.
Energy Efficiency Optimization for MIMO Broadcasting Channels
Xu, Jie
2012-01-01
Optimizing the energy efficiency (EE) for the MIMO broadcasting channels (BC) is addressed in this paper, taking into account the transmit independent power which is related to the active transmit antenna number. A new optimization framework is proposed, in which transmit covariance optimization under fixed active transmit antenna sets is first performed and active transmit antenna selection (ATAS) is utilized then. To optimize the EE under a fixed transmit antenna set, we propose an energy efficient iterative waterfilling scheme according to the block-coordinate ascent algorithm, through transforming the problem into a concave fractional optimization via uplink-downlink duality. It is proved that the proposed scheme converges to the global optimality. After that, ATAS is employed to determine the active transmit antenna set and to turn off the rest inactive antennas. ATAS can balance the active transmit antenna number related EE gain with higher capacity gain and the EE loss with more transmit independent po...
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.
Antenna Pattern Impact on MIMO OTA Testing
DEFF Research Database (Denmark)
Fan, Wei; Nielsen, Jesper Ødum; Franek, Ondrej
2013-01-01
This paper investigates the impact of the DUT antenna pattern on the test area performance for multi-probe based MIMO OTA setup in terms of received voltage and spatial correlation. The plane wave synthesis (PWS) technique has been proposed for vertical polarization in the literature, where...... the goal is to approximate plane waves with arbitrary directions. The received voltage at the antenna terminal depends on the antenna radiation pattern and the impinging plane waves. A novel closed form technique to reproduce the received voltage with arbitrary incoming plane waves based on trigonometric...... interpolation is presented. The proposed technique provides a closed form solution for the PWS when the probe ring radius is infinite. The proposed technique shows that the impact of the antenna pattern on the induced received voltage accuracy is ruled by Nyquist sampling theory. Furthermore, the impact...
Navarro, Andres A
2013-01-01
We analyze a massive vector field with a non-canonical kinetic term in the action, minimally coupled to gravity, where the mass and kinetic function of the vector field vary as functions of time during inflation. The vector field is introduced following the same idea of a scalar curvaton, which must not affect the inflationary dynamics since its energy density during inflation is negligible compared to the total energy density in the Universe. Using this hypothesis, the vector curvaton will be solely responsible for generating the primordial curvature perturbation \\zeta. We have found that the spectra of the vector field perturbations are scale-invariant in superhorizon scales due to the suitable choice of the time dependence of the kinetic function and the effective mass during inflation. The preferred direction, generated by the vector field, makes the spectrum of \\zeta depend on the wavevector, i.e. there exists statistical anisotropy in \\zeta. This is discussed principally in the case where the mass of th...
MimoSA: a system for minimotif annotation
Directory of Open Access Journals (Sweden)
Kundeti Vamsi
2010-06-01
Full Text Available Abstract Background Minimotifs are short peptide sequences within one protein, which are recognized by other proteins or molecules. While there are now several minimotif databases, they are incomplete. There are reports of many minimotifs in the primary literature, which have yet to be annotated, while entirely novel minimotifs continue to be published on a weekly basis. Our recently proposed function and sequence syntax for minimotifs enables us to build a general tool that will facilitate structured annotation and management of minimotif data from the biomedical literature. Results We have built the MimoSA application for minimotif annotation. The application supports management of the Minimotif Miner database, literature tracking, and annotation of new minimotifs. MimoSA enables the visualization, organization, selection and editing functions of minimotifs and their attributes in the MnM database. For the literature components, Mimosa provides paper status tracking and scoring of papers for annotation through a freely available machine learning approach, which is based on word correlation. The paper scoring algorithm is also available as a separate program, TextMine. Form-driven annotation of minimotif attributes enables entry of new minimotifs into the MnM database. Several supporting features increase the efficiency of annotation. The layered architecture of MimoSA allows for extensibility by separating the functions of paper scoring, minimotif visualization, and database management. MimoSA is readily adaptable to other annotation efforts that manually curate literature into a MySQL database. Conclusions MimoSA is an extensible application that facilitates minimotif annotation and integrates with the Minimotif Miner database. We have built MimoSA as an application that integrates dynamic abstract scoring with a high performance relational model of minimotif syntax. MimoSA's TextMine, an efficient paper-scoring algorithm, can be used to
MIMO 4x4 Link Level Simulations in Anisotropic Channel Environments
DEFF Research Database (Denmark)
Szini, Istvan Janos; Buris, Nick
MIMO Over the Air (OTA) Measurements in controlled enviromments has been investigated both in academia (1-2) and industry standardization Groups (3-4). A several year effort to define MIMO OTA test methodologies, adequate channel models (5), channel model validation methods (6), etc. resulted...... in a Multi Probe Anechoic Chamber (MPAC) to serve as a reference for MIMO OTA performance certification for 2x2 downlink only. While efforts were made to cenverge MIMO OTA Measurements with simulations, the closest results were achieved when adopting the concept of Absolute Data Throughput Framework (ADTF...... in the MIMO OTA standardization Groups....
Perturbative partition function for squashed S^5
Imamura, Yosuke
2012-01-01
We compute the index of 6d N=(1,0) theories on S^5xR containing vector and hypermultiplets. We only consider the perturbative sector without instantons. By compactifying R to S^1 with a twisted boundary condition and taking the small radius limit, we derive the perturbative partition function on a squashed S^5. The 1-loop partition function is represented in a simple form with the triple sine function.
Measurement-Based Performance Evaluation of Advanced MIMO Transceiver Designs
Trautwein, Uwe; Schneider, Christian; Thomä, Reiner
2005-12-01
This paper describes the methodology and the results of performance investigations on a multiple-input multiple-output (MIMO) transceiver scheme for frequency-selective radio channels. The method relies on offline simulations and employs real-time MIMO channel sounder measurement data to ensure a realistic channel modeling. Thus it can be classified in between the performance evaluation using some predefined channel models and the evaluation of a prototype hardware in field experiments. New aspects for the simulation setup are discussed, which are frequently ignored when using simpler model-based evaluations. Example simulations are provided for an iterative ("turbo") MIMO equalizer concept. The dependency of the achievable bit error rate performance on the propagation characteristics and on the variation in some system design parameters is shown, whereas the antenna constellation is of particular concern for MIMO systems. Although in many of the considered constellations turbo MIMO equalization appears feasible in real field scenarios, there exist cases with poor performance as well, indicating that in practical applications link adaptation of the transmitter and receiver processing to the environment is necessary.
Analysis of Energy Consumption of Virtual MIMO Wireless Sensor Network
Directory of Open Access Journals (Sweden)
Yongxian Song
2012-12-01
Full Text Available In order to solve the problem that the existing virtual multiple-input multiple-output (Virtual MIMO routing algorithm isn't suitable to isomorphism wireless sensor network, virtual MIMO clustering (VMC algorithm which is applicable to small and medium scale isomorphism WSN is proposed. By combining the energy-efficient virtual MIMO communication technology with the method that cluster heads are selected randomly and cyclically, energy load of network is balanced and life of WSN is extended. We build energy test platform of wireless sensor network with microcontroller MSP430F135 and wireless radio transceiver chip CC2420. The relation between transmitting power and the RSSI is researched by the experimental platform in greenhouse, the path loss factor is solved, and the energy model of virtual MIMO clustering network is created. Then, we focus on the effect of the network size, node density and path loss factor on the virtual MIMO WSN energy-saving performance. To achieve the optimization objective that the longest life of the network, we adopt the genetic algorithm to optimize the ratio of cluster head which is a key parameter of WSN. The simulation results show that the VMC has more energy-efficient and longer lifetime than LEACH. When the parameters of network structure are appropriate, the lifetime can be extended several times.
Measurement-Based Performance Evaluation of Advanced MIMO Transceiver Designs
Directory of Open Access Journals (Sweden)
Schneider Christian
2005-01-01
Full Text Available This paper describes the methodology and the results of performance investigations on a multiple-input multiple-output (MIMO transceiver scheme for frequency-selective radio channels. The method relies on offline simulations and employs real-time MIMO channel sounder measurement data to ensure a realistic channel modeling. Thus it can be classified in between the performance evaluation using some predefined channel models and the evaluation of a prototype hardware in field experiments. New aspects for the simulation setup are discussed, which are frequently ignored when using simpler model-based evaluations. Example simulations are provided for an iterative ("turbo" MIMO equalizer concept. The dependency of the achievable bit error rate performance on the propagation characteristics and on the variation in some system design parameters is shown, whereas the antenna constellation is of particular concern for MIMO systems. Although in many of the considered constellations turbo MIMO equalization appears feasible in real field scenarios, there exist cases with poor performance as well, indicating that in practical applications link adaptation of the transmitter and receiver processing to the environment is necessary.
In-situ Moessbauer spectroscopy with MIMOS II
Energy Technology Data Exchange (ETDEWEB)
Fleischer, Iris, E-mail: fleischi@uni-mainz.de; Klingelhoefer, Goestar [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University of Mainz (Germany); Morris, Richard V. [NASA Johnson Space Center (United States); Schroeder, Christian [University of Bayreuth and University of Tuebingen (Germany); Rodionov, Daniel [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University of Mainz (Germany); Souza, Paulo A. de [Tasmanian ICT Centre (Australia); Collaboration: MIMOS II Team
2012-03-15
The miniaturized Moessbauer spectrometer MIMOS II was developed for the exploration of planetary surfaces. Two MIMOS II instruments were successfully deployed on the martian surface as payload elements of the NASA Mars Exploration Rover (MER) mission and have returned data since landing in January 2004. Moessbauer spectroscopy has made significant contributions to the success of the MER mission, in particular identification of iron-bearing minerals formed through aqueous weathering processes. As a field-portable instrument and with backscattering geometry, MIMOS II provides an opportunity for non-destructive in-situ investigations for a range of applications. For example, the instrument has been used for analyses of archaeological artifacts, for air pollution studies and for in-field monitoring of green rust formation. A MER-type MIMOS II instrument is part of the payload of the Russian Phobos-Grunt mission, scheduled for launch in November 2011, with the aim of exploring the composition of the martian moon Phobos. An advanced version of the instrument, MIMOS IIA, that incorporates capability for elemental analyses, is currently under development.
Scaling up MIMO: Opportunities and Challenges with Very Large Arrays
Rusek, Fredrik; Lau, Buon Kiong; Larsson, Erik G; Marzetta, Thomas L; Edfors, Ove; Tufvesson, Fredrik
2012-01-01
This paper surveys recent advances in the area of very large MIMO systems. With very large MIMO, we think of systems that use antenna arrays with an order of magnitude more elements than in systems being built today, say a hundred antennas or more. Very large MIMO entails an unprecedented number of antennas simultaneously serving a much smaller number of terminals. The disparity in number emerges as a desirable operating condition and a practical one as well. The number of terminals that can be simultaneously served is limited, not by the number of antennas, but rather by our inability to acquire channel-state information for an unlimited number of terminals. Larger numbers of terminals can always be accommodated by combining very large MIMO technology with conventional time- and frequency-division multiplexing via OFDM. Very large MIMO arrays is a new research field both in communication theory, propagation, and electronics and represents a paradigm shift in the way of thinking both with regards to theory, s...
Acoustic MIMO Communications in a Very Shallow Water Channel
Institute of Scientific and Technical Information of China (English)
Yuehai Zhou; Xiuling Cao; Feng Tong
2015-01-01
Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple-input multiple-output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.
Cosmological density perturbations from perturbed couplings
Tsujikawa, S
2003-01-01
The density perturbations generated when the inflaton decay rate is perturbed by a light scalar field $\\chi$ are studied. By explicitly solving the perturbation equations for the system of two scalar fields and radiation, we show that even in low energy-scale inflation nearly scale-invariant spectra of scalar perturbations with an amplitude set by observations are obtained through the conversion of $\\chi$ fluctuations into adiabatic density perturbations. We demonstrate that the spectra depend on the average decay rate of the inflaton & on the inflaton fluctuations. We then apply this new mechanism to string cosmologies & generalized Einstein theories and discuss the conditions under which scale-invariant spectra are possible.
Two-Stage Over-the-Air (OTA Test Method for LTE MIMO Device Performance Evaluation
Directory of Open Access Journals (Sweden)
Ya Jing
2012-01-01
Full Text Available With MIMO technology being adopted by the wireless communication standards LTE and HSPA+, MIMO OTA research has attracted wide interest from both industry and academia. Parallel studies are underway in COST2100, CTIA, and 3GPP RAN WG4. The major test challenge for MIMO OTA is how to create a repeatable scenario which accurately reflects the MIMO antenna radiation performance in a realistic wireless propagation environment. Different MIMO OTA methods differ in the way to reproduce a specified MIMO channel model. This paper introduces a novel, flexible, and cost-effective method for measuring MIMO OTA using a two-stage approach. In the first stage, the antenna pattern is measured in an anechoic chamber using a nonintrusive approach, that is without cabled connections or modifying the device. In the second stage, the antenna pattern is convolved with the chosen channel model in a channel emulator to measure throughput using a cabled connection.
Body Loss Study of Beamforming Mode in LTE MIMO Mobile Terminals
DEFF Research Database (Denmark)
Zhang, Shuai; Zhao, Kun; Ying, Zhinong
2015-01-01
This paper mainly focuses on the investigation of the body loss of beamforming mode in LTE MIMO mobile terminals with CTIA user effects. The research of the body loss and radiation efficiency is carried out over different phase differences between two ports of each MIMO antenna. During studies......, four kinds of typical LTE MIMO antennas are used, namely, collocated ground free (GF), parallel GF, parallel on ground (OG) and orthogonal OG MIMO antennas, under four mobile terminal lengths at low and high frequencies. Two kinds of CTIA user effects are included in the research. From the studies......, the parallel GF MIMO antenna type exhibits the best beamforming performance in the four MIMO antenna types. In order to verify the simulations, envelope correlation coefficients of two MIMO antenna prototypes are measured. All the measured results agree well with the simulated....
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.
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.
A Close Look at MIMO OFDM WLAN and Its Key Technology%MIMO OFDM无线局域网的研究及其关键技术
Institute of Scientific and Technical Information of China (English)
韩旭东; 张春业; 曹建海
2004-01-01
MIMO技术与OFDM技术相结合被视为下一代高速无线局域网的核心技术.本文全面叙述了MIMO OFDM技术及其特点,分析了MIMO OFDM技术在无线局域网中的应用,探讨了MIMO OFDM中的关键技术,并展望了其发展前景.
Application of 3D-MIMO Technology in Beyond LTE Era%3D-MIMO技术在后LTE时代中的应用
Institute of Scientific and Technical Information of China (English)
张彬; 温正阳
2015-01-01
3D-MIMO technology based on the active antenna array is an evolution of MIMO technology in LTE systems at present. It can make full use of space domain and further improve the performance of wireless communication system. Firstly, the technical features and the typical application scenes of 3D-MIMO technology were introduced. Then, a 3D dynamic beam forming algorithm based on SVD of channel state matrix was presented. In this algorithm, the two dimensions of base station antenna array and the SVD decomposed vector of channel matrix of the receiving antenna were combined to form a beam forming vector of the transmitter. Finally, the algorithm provides useful reference to the practical application of 3D-MIMO technology.%基于有源天线阵列的3D-MIMO技术是目前LTE系统中MIMO技术的演进，对空间域的利用更加充分，可进一步提升无线通信系统的性能。通过介绍3D-MIMO的技术特点及典型应用场景，提出了一种基于矩阵奇异值分解的三维动态波束赋形算法，该算法对基站天线阵列两个维度与接收天线之间的信道矩阵的SVD分解向量进行组合得到发射端波束赋形向量，为3D-MIMO的实际应用提供参考。
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.
A novel mirror diversity receiver for indoor MIMO visible light
Park, Ki-Hong
2016-03-01
In this paper, we propose and study a non-imaging receiver design reducing the correlation of channel matrix for indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems. Contrary to previous works, our proposed mirror diversity receiver (MDR) not only blocks the reception of light on one specific direction but also improves the channel gain on the other direction by receiving the light reflected by a mirror deployed between the photodetectors. We analyze the channel capacity and optimal height of mirror in terms of maximum channel capacity for a 2 -by-2 MIMO-VLC system in a 2-dimensional geometric model.We prove that this constructive and destructive effects in channel matrix resulting from our proposed MDR are more beneficial to obtain well-conditioned channel matrix which is suitable for implementing spatial-multiplexing MIMO-VLC systems in order to support high data rate.
Modified Spatial Channel Model for MIMO Wireless Systems
Directory of Open Access Journals (Sweden)
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.
Array independent MIMO channel models with analytical characteristics
Yao, Yuan; Feng, Zhenghe
2011-01-01
The conventional analytical channel models for multiple-input multiple-output (MIMO) wireless radio channels are array dependent. In this paper, we present several array independent MIMO channel models that inherit the essence of analytical models. The key idea is to decompose the physical scattering channel into two parts using the manifold decomposition technique: one is the wavefield independent sampling matrices depending on the antenna arrays only; the other is the array independent physical channel that can be individually modeled in an analytical manner. Based on the framework, we firstly extend the conventional virtual channel representation (VCR), which is restricted to uniform linear arrays (ULAs) so far, to a general version applicable to arbitrary array configurations. Then, we present two array independent stochastic MIMO channel models based on the proposed new VCR as well as the Weichselberger model. These two models are good at angular power spectrum (APS) estimation and capacity prediction, r...
MIMO ARQ with Multi-bit Feedback: Outage Analysis
Nguyen, Khoa D; Fabregas, Albert Guillen i; Letzepis, Nick
2010-01-01
We study the asymptotic outage performance of incremental redundancy automatic repeat request (INR-ARQ) transmission over the multiple-input multiple-output (MIMO) block-fading channels with discrete input constellations. We first show that transmission with random codes using a discrete signal constellation across all transmit antennas achieves the optimal outage diversity given by the Singleton bound. We then analyze the optimal SNR-exponent and outage diversity of INR-ARQ transmission over the MIMO block-fading channel. We show that a significant gain in outage diversity is obtained by providing more than one bit feedback at each ARQ round. Thus, the outage performance of INR-ARQ transmission can be remarkably improved with minimal additional overhead. A suboptimal feedback and power adaptation rule, which achieves the optimal outage diversity, is proposed for MIMO INR-ARQ, demonstrating the benefits provided by multi-bit feedback.
Transceiver design for dispersive MIMO channels with decision feedback
Huang, Wan-Jen; Yu, Xiaoli; Kuo, C.-C. J.
2005-06-01
A finite impulse response (FIR) precoder for the multi-input multi-output (MIMO) channel is proposed to eliminate the intersymbol interference (ISI) effect in this research. Two precoders are designed to maximize the signal to noise ratio (SNR) and the signal to interference plus noise ratio (SINR), respectively. At the receiver end, a finite-length MIMO decision feedback equalizer is adopted to minimize the mean squared error (MSE) of the overall system. It is observed that the SINR-maximizing precoder performs the best among all precoders under our examination. For the 2x2 MIMO channel, the simple one-tap SNR-maximizing precoder can perform almost as well. For a heavily dispersive channel, the SINR-maximizing precoder still performs well even its length is much smaller than the channel length.
MIMO Transmission with Residual Transmit-RF Impairments
Studer, Christoph; Burg, Andreas
2010-01-01
Physical transceiver implementations for multiple-input multiple-output (MIMO) wireless communication systems suffer from transmit-RF (Tx-RF) impairments. In this paper, we study the effect on channel capacity and error-rate performance of residual Tx-RF impairments that defy proper compensation. In particular, we demonstrate that such residual distortions severely degrade the performance of (near-)optimum MIMO detection algorithms. To mitigate this performance loss, we propose an efficient algorithm, which is based on an i.i.d. Gaussian model for the distortion caused by these impairments. In order to validate this model, we provide measurement results based on a 4-stream Tx-RF chain implementation for MIMO orthogonal frequency-division multiplexing (OFDM).
Single Front-End MIMO Architecture with Parasitic Antenna Elements
Yoshida, Mitsuteru; Sakaguchi, Kei; Araki, Kiyomichi
In recent years, wireless communication technology has been studied intensively. In particular, MIMO which employs several transmit and receive antennas is a key technology for enhancing spectral efficiency. However, conventional MIMO architectures require some transceiver circuits for the sake of transmitting and receiving separate signals, which incurs the cost of one RF front-end per antenna. In addition to that, MIMO systems are assumed to be used in low spatial correlation environment between antennas. Since a short distance between each antenna causes high spatial correlation and coupling effect, it is difficult to miniaturize wireless terminals for mobile use. This paper shows a novel architecture which enables mobile terminals to be miniaturized and to work with a single RF front-end by means of adaptive analog beam-forming with parasitic antenna elements and antenna switching for spatial multiplexing. Furthermore, statistical analysis of the proposed architecture is also discussed in this paper.
Massive MIMO meets small cell backhaul and cooperation
Yang, Howard H
2017-01-01
This brief explores the utilization of large antenna arrays in massive multiple-input-multiple-output (MIMO) for both interference suppression, where it can improve cell-edge user rates, and for wireless backhaul in small cell networks, where macro base stations can forward data to small access points in an energy efficient way. Massive MIMO is deemed as a critical technology for next generation wireless technology. By deploying an antenna array that has active elements in excess of the number of users, massive MIMO not only provides tremendous diversity gain but also powers new aspects for network design to improve performance. This brief investigates a better utilization of the excessive spatial dimensions to improve network performance. It combines random matrix theory and stochastic geometry to develop an analytical framework that accounts for all the key features of a network, including number of antenna array, base station density, inter-cell interference, random base station deployment, and network tra...
Performance Analysis of 802.lln MIMO OFDM Transceiver
Directory of Open Access Journals (Sweden)
Allan Lopes,
2014-07-01
Full Text Available The increasing demand on real time application to achieve high throughput, reliable wireless system and network capacity for fourth generation wireless local area networks is to combine MIMO wireless technology with OFDM. Orthogonal Frequency Division Multiplexing (OFDM, which offers reliable high bit rate wireless system with reasonable low complexity. OFDM does provide large data rates with sufficient robustness to radio channel impairments. OFDM is a combination of modulation and multiplexing and are able to maximize spectral efficiency without causing adjacent channel interference. This paper first focuses on 802.11n standard, MIMO-OFDM system. This paper further reviews different work done on implementation of MIMO-OFDM transceiver for 802.11n standard.
Secret Sharing over Fast-Fading MIMO Wiretap Channels
Directory of Open Access Journals (Sweden)
Bloch Matthieu
2009-01-01
Full Text Available Secret sharing over the fast-fading MIMO wiretap channel is considered. A source and a destination try to share secret information over a fast-fading MIMO channel in the presence of an eavesdropper who also makes channel observations that are different from but correlated to those made by the destination. An interactive, authenticated public channel with unlimited capacity is available to the source and destination for the secret sharing process. This situation is a special case of the "channel model with wiretapper" considered by Ahlswede and Csiszár. An extension of their result to continuous channel alphabets is employed to evaluate the key capacity of the fast-fading MIMO wiretap channel. The effects of spatial dimensionality provided by the use of multiple antennas at the source, destination, and eavesdropper are then investigated.
A Novel Pilot Expansion Approach for MIMO Channel Estimation
Directory of Open Access Journals (Sweden)
Ming Fei SIYAU
2015-05-01
Full Text Available A training-based MIMO channel estimation scheme is presented to operate in severe frequency and time selective fading channels. Besides the new pilot bits designed from the ‘Paley-Hadamard’ matrix to exploit its orthogonal and ‘Toeplitz-like’ structures and minimising its pilot length, a novel pilot expansion technique is proposed to estimate the length of the channel impulse response, by flexibly extending its pilot length as required in order to capture the number of multipath existed within the MIMO channel. The pilot expansion can also help to deduce the initial channel variation and its Doppler rate which can be subsequently applied for MIMO channel tracking using decision feedback Kalman filter during the data payload.
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.
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.
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.
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.
Over the Air Testing of MIMO Capable Terminals
DEFF Research Database (Denmark)
Fan, Wei
devices, where the focus is on techniques to emulate radio channels in multi-probe setups with a limited number of probes. Several channel emulation techniques are proposed to create realistic 2D and 3D spatial channel models in the thesis. A novel method to calculate probe weights for the prefaded signal......This thesis focuses on multi-probe anechoic chamber testing, which is a promising over the air (OTA) testing method to evaluate multiple-input multiple-output (MIMO) capable terminals. With MIMO technology being adopted by new wireless technologies, mobile manufacturers and cellular operators need...
Energy Efficient Iterative Waterfilling for the MIMO Broadcasting Channels
Xu, Jie; Zhang, Shunqing
2012-01-01
Optimizing energy efficiency (EE) for the MIMO broadcasting channels (BC) is considered in this paper, where a practical power model is taken into account. Although the EE of the MIMO BC is non-concave, we reformulate it as a quasiconcave function based on the uplink-downlink duality. After that, an energy efficient iterative waterfilling scheme is proposed based on the block-coordinate ascent algorithm to obtain the optimal transmission policy efficiently, and the solution is proved to be convergent. Through simulations, we validate the efficiency of the proposed scheme and discuss the system parameters' effect on the EE.
Diffractive Leptoproduction of Vector Mesons in QCD
Brodsky, Stanley J.; Frankfurt, L.; Gunion, J. F.; Mueller, A.H.; Strikman, M.
1994-01-01
We demonstrate that the distinctive features of the forward differential cross section of diffractive leptoproduction of a vector meson can be legitimately calculated in perturbative QCD in terms of the light-cone $q \\bar q$ wave function of the vector meson and the gluon distribution of the target. In particular, we calculate the $Q^2$ and nuclear dependence of the diffractive leptoproduction of vector mesons and estimate the cross section. The production of longitudinally polarized vector m...
Constrained Optimization of MIMO Training Sequences
Directory of Open Access Journals (Sweden)
Coon Justin P
2007-01-01
Full Text Available Multiple-input multiple-output (MIMO systems have shown a huge potential for increased spectral efficiency and throughput. With an increasing number of transmitting antennas comes the burden of providing training for channel estimation for coherent detection. In some special cases optimal, in the sense of mean-squared error (MSE, training sequences have been designed. However, in many practical systems it is not feasible to analytically find optimal solutions and numerical techniques must be used. In this paper, two systems (unique word (UW single carrier and OFDM with nulled subcarriers are considered and a method of designing near-optimal training sequences using nonlinear optimization techniques is proposed. In particular, interior-point (IP algorithms such as the barrier method are discussed. Although the two systems seem unrelated, the cost function, which is the MSE of the channel estimate, is shown to be effectively the same for each scenario. Also, additional constraints, such as peak-to-average power ratio (PAPR, are considered and shown to be easily included in the optimization process. Numerical examples illustrate the effectiveness of the designed training sequences, both in terms of MSE and bit-error rate (BER.
Non-perturbative Heavy Quark Effective Theory
DEFF Research Database (Denmark)
Della Morte, Michele; Heitger, Jochen; Simma, Hubert;
2015-01-01
We review a lattice strategy how to non-perturbatively determine the coefficients in the HQET expansion of all components of the heavy-light axial and vector currents, including 1/m_h-corrections. We also discuss recent preliminary results on the form factors parameterizing semi-leptonic B-decays...
Non-perturbative Heavy Quark Effective Theory
DEFF Research Database (Denmark)
Della Morte, Michele; Heitger, Jochen; Simma, Hubert
2015-01-01
We review a lattice strategy how to non-perturbatively determine the coefficients in the HQET expansion of all components of the heavy-light axial and vector currents, including 1/m_h-corrections. We also discuss recent preliminary results on the form factors parameterizing semi-leptonic B-decays...
Relationship Between Capacity and Pathloss for Indoor MIMO Channels
DEFF Research Database (Denmark)
Nielsen, Jesper Ødum; Andersen, Jørgen Bach; Bauch, Gerhard
2006-01-01
MIMO transmission systems exploit scattering in the radio channel to achieve high capacity for a given SNR. A high pathloss is generally expected for channels with rich scattering, suggesting that a high SNR and rich multipath are competing goals. The current work investigates this issue based...
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.
Sparse Recovery Algorithms for Pilot Assisted MIMO OFDM Channel Estimation
Qi, Chenhao; Wu, Lenan
In this letter, the sparse recovery algorithm orthogonal matching pursuit (OMP) and subspace pursuit (SP) are applied for MIMO OFDM channel estimation. A new algorithm named SOMP is proposed, which combines the advantage of OMP and SP. Simulation results based on 3GPP spatial channel model (SCM) demonstrate that SOMP performs better than OMP and SP in terms of normalized mean square error (NMSE).
LFMCW based MIMO imaging processing with keystone transform
Dorp, P. van
2013-01-01
In this paper, a new signal processing technique for Multiple-Input Multiple-Output (MIMO) image processing of a Linear Frequency-Modulated Continuous Wave (LFMCW) automotive radar was developed. The image is the range-speed-direction data cube. The technique comprises two improvements to the
MIMO Self-Tuning Control of Chemical Process Operation
DEFF Research Database (Denmark)
Hallager, L.; Jørgensen, S. B.; Goldschmidt, L.
1984-01-01
The problem of selecting a feasible model structure for a MIMO self-tuning controller (MIMOSC) is addressed. The dependency of the necessary structure complexity in relation to the specific process operating point is investigated. Experimental results from a fixed-bed chemical reactor are used...
On Small Antenna Measurements in a Realistic MIMO Scenario
DEFF Research Database (Denmark)
Yanakiev, Boyan; Nielsen, Jesper Ødum; Pedersen, Gert Frølund
2010-01-01
This paper deals with the challenges related to evaluating the performance of multiple, small terminal antennas within a natural MIMO environment. The focus is on the antenna measurement accuracy. First a method is presented for measuring small phone mock-ups, with the use of optical fibers...
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...
Evaluation of Reflections in a MIMO OTA Test Setup
DEFF Research Database (Denmark)
Barrio, Samantha Caporal Del; Franek, Ondrej; Krenz, Gunter
2014-01-01
With the commercialization of MIMO devices, accurate over-the-air testing has become a major research area in mobile communications. Several test methods are investigated in the related work. This paper discusses the anechoic chamber method and specifically deals with reflections between probes...
Over-the-Air Testing of MIMO-Capable Terminals
DEFF Research Database (Denmark)
Fan, Wei; Carreño, Xavier; Kyösti, Pekka
2015-01-01
A new over-the-air (OTA) testing method is required for evaluating multiple-antenna systems in realistic multipath propagation environments. Antenna design and propagation channels are the two key parameters that ultimately determine the multiple-input, multiple-output (MIMO) device performance. ...
Emulating Realistic Bidirectional Spatial Channels for MIMO OTA Testing
DEFF Research Database (Denmark)
Fan, Wei; Kyösti, Pekka; Nielsen, Jesper Ødum
2015-01-01
This paper discusses over the air (OTA) testing for multiple input multiple output (MIMO) capable terminals with emphasis on modeling bidirectional spatial channel models in multiprobe anechoic chamber (MPAC) setups. In the literature, work on this topic has been mainly focused on how to emulate ...
MIMO-OFDM performance in relation to wideband channel properties
Li, P.; Zhang, H.; Oostveen, J.; Fledderus, E.
2010-01-01
In this paper, the sensitivity of the error rate performance of MIMO-OFDM-based practical systems (WiMAX and LTE) to wide band channel properties is investigated. The behavior of the wideband channel is characterized in terms of delay spread (DS) and angular spread (AS). The impacts of DS and AS on
3D Channel Model Emulation in a MIMO OTA Setup
DEFF Research Database (Denmark)
Fan, Wei; Kyösti, Pekka; Sun, Fan
2013-01-01
This paper presents a new channel reconstruction technique for 3D geometry-based channels in a multi-probe based MIMO OTA setup. The proposed method provides a general channel reconstruction framework for any spherical power spectrum. The channel reconstruction is formed as convex optimization...
Perturbative unitarity of Higgs derivative interactions
Kikuta, Yohei
2012-01-01
We study the perturbative unitarity bound given by dimension six derivative interactions consisting of Higgs doublets. These operators emerge from kinetic terms of composite Higgs models or integrating out heavy particles that interact with Higgs doublets. They lead to new phenomena beyond the Standard Model. One of characteristic contributions by derivative interactions appear in vector boson scattering processes. Longitudinal modes of massive vector bosons can be regarded as Nambu Goldstone bosons eaten by each vector field with the equivalence theorem. Since their effects become larger and larger as the collision energy of vector bosons increases, vector boson scattering processes become important in a high energy region around the TeV scale. On the other hand, in such a high energy region, we have to take the unitarity of amplitudes into account. We have obtained the unitarity condition in terms of the parameter included in the effective Lagrangian for one Higgs doublet models. Applying it to some of mode...
Directory of Open Access Journals (Sweden)
Yin Zhu
2016-05-01
Full Text Available Interference alignment (IA is a new approach to address interference in modern multiple-input multiple-out (MIMO cellular networks in which interference is an important factor that limits the system throughput. System throughput in most IA implementation schemes is significantly improved only with perfect channel state information and in a high signal-to-noise ratio (SNR region. Designing a simple IA scheme for the system with limited feedback and investigating system performance at a low-to-medium SNR region is important and practical. This paper proposed a precoding and user selection scheme based on partial interference alignment in two-cell downlink multi-user MIMO systems under limited feedback. This scheme aligned inter-cell interference to a predefined direction by designing user’s receive antenna combining vectors. A modified singular value decomposition (SVD-based beamforming method and a corresponding user-selection algorithm were proposed for the system with low rate limited feedback to improve sum rate performance. Simulation results show that the proposed scheme achieves a higher sum rate than traditional schemes without IA. The modified SVD-based beamforming scheme is also superior to the traditional zero-forcing beamforming scheme in low-rate limited feedback systems. The proposed partial IA scheme does not need to collaborate between transmitters and joint design between the transmitter and the users. The scheme can be implemented with low feedback overhead in current MIMO cellular networks.
Hoffmann, Banesh
1975-01-01
From his unusual beginning in ""Defining a vector"" to his final comments on ""What then is a vector?"" author Banesh Hoffmann has written a book that is provocative and unconventional. In his emphasis on the unresolved issue of defining a vector, Hoffmann mixes pure and applied mathematics without using calculus. The result is a treatment that can serve as a supplement and corrective to textbooks, as well as collateral reading in all courses that deal with vectors. Major topics include vectors and the parallelogram law; algebraic notation and basic ideas; vector algebra; scalars and scalar p
Newell, Homer E
2006-01-01
When employed with skill and understanding, vector analysis can be a practical and powerful tool. This text develops the algebra and calculus of vectors in a manner useful to physicists and engineers. Numerous exercises (with answers) not only provide practice in manipulation but also help establish students' physical and geometric intuition in regard to vectors and vector concepts.Part I, the basic portion of the text, consists of a thorough treatment of vector algebra and the vector calculus. Part II presents the illustrative matter, demonstrating applications to kinematics, mechanics, and e
Characteristic analysis on UAV-MIMO channel based on normalized correlation matrix.
Gao, Xi jun; Chen, Zi li; Hu, Yong Jiang
2014-01-01
Based on the three-dimensional GBSBCM (geometrically based double bounce cylinder model) channel model of MIMO for unmanned aerial vehicle (UAV), the simple form of UAV space-time-frequency channel correlation function which includes the LOS, SPE, and DIF components is presented. By the methods of channel matrix decomposition and coefficient normalization, the analytic formula of UAV-MIMO normalized correlation matrix is deduced. This formula can be used directly to analyze the condition number of UAV-MIMO channel matrix, the channel capacity, and other characteristic parameters. The simulation results show that this channel correlation matrix can be applied to describe the changes of UAV-MIMO channel characteristics under different parameter settings comprehensively. This analysis method provides a theoretical basis for improving the transmission performance of UAV-MIMO channel. The development of MIMO technology shows practical application value in the field of UAV communication.
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.
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.
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...
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...
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...
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.
Brane World Cosmological Perturbations
Casali, A G; Wang, B; Casali, Adenauer G.; Abdalla, Elcio; Wang, Bin
2004-01-01
We consider a brane world and its gravitational linear perturbations. We present a general solution of the perturbations in the bulk and find the complete perturbed junction conditions for generic brane dynamics. We also prove that (spin 2) gravitational waves in the great majority of cases can only arise in connection with a non-vanishing anisotropic stress. This has far reaching consequences for inflation in the brane world. Moreover, contrary to the case of the radion, perturbations are stable.
DEFF Research Database (Denmark)
Sadegh, Payman; Spall, J. C.
1998-01-01
The simultaneous perturbation stochastic approximation (SPSA) algorithm has attracted considerable attention for challenging optimization problems where it is difficult or impossible to obtain a direct gradient of the objective (say, loss) function. The approach is based on a highly efficient...... simultaneous perturbation approximation to the gradient based on loss function measurements. SPSA is based on picking a simultaneous perturbation (random) vector in a Monte Carlo fashion as part of generating the approximation to the gradient. This paper derives the optimal distribution for the Monte Carlo...
DEFF Research Database (Denmark)
Sadegh, Payman; Spall, J. C.
1997-01-01
The simultaneous perturbation stochastic approximation (SPSA) algorithm has recently attracted considerable attention for optimization problems where it is difficult or impossible to obtain a direct gradient of the objective (say, loss) function. The approach is based on a highly efficient...... simultaneous perturbation approximation to the gradient based on loss function measurements. SPSA is based on picking a simultaneous perturbation (random) vector in a Monte Carlo fashion as part of generating the approximation to the gradient. This paper derives the optimal distribution for the Monte Carlo...
Mutual Coupling Reduction for UWB MIMO Antennas with a Wideband Neutralization Line
DEFF Research Database (Denmark)
Zhang, Shuai; Pedersen, Gert F.
2016-01-01
A wideband neutralization line is proposed to reduce the mutual coupling of a compact ultrawideband (UWB) MIMO antenna. With the introduced decoupling method, the designed UWB MIMO antenna covers the band of 3.1-5 GHz with an isolation of higher than 22 dB. The proposed wideband neutralization line...... is not necessarily placed in the clearance area between two MIMO elements and can be put above the copper ground. A small clearance (antenna area) of 35 mm × 16 mm is achieved. The designed UWB MIMO antenna is fabricated. S parameters, radiation patterns, total efficiency and realized gain of the prototype...
ANALISIS UNJUK KERJA TEKNIK PENGKODEAN STBC DAN WATERFILLING PADA SISTEM D-MIMO
Directory of Open Access Journals (Sweden)
I Nyoman Gunantara
2009-05-01
Full Text Available Kemajuan teknologi komunikasi, maka dikembangkan sistem D-MIMO (Distributed MIMO. Pada sistem D-MIMO, fading yang mempengaruhi adalah fading skala besar dan fading skala kecil. Kedua jenis fading itu akan mengakibatkan kualitas sinyal akan menjadi berkurang yang akhirnya menurunkan unjuk kerja sistem komunikasi. Untuk mengantisipasi hal tersebut maka dikembangkan teknik pengkodean STBC dan waterfilling. Pada konfigurasi sistem D-MIMO yang sama untuk teknik pengkodean STBC dan teknik waterfilling maka diperoleh unjuk kerja teknik pengkodean STBC lebih baik dibandingkan dengan teknik waterfilling.
Performance Analysis of Virtual MIMO Relaying Schemes Based on Detect–Split–Forward
Al-Basit, Suhaib M.
2014-10-29
© 2014, Springer Science+Business Media New York. Virtual multi-input multi-output (vMIMO) schemes in wireless communication systems improve coverage, throughput, capacity, and quality of service. In this paper, we propose three uplink vMIMO relaying schemes based on detect–split–forward (DSF). In addition, we investigate the effect of several physical parameters such as distance, modulation type and number of relays. Furthermore, an adaptive vMIMO DSF scheme based on VBLAST and STBC is proposed. In order to do that, we provide analytical tools to evaluate the performance of the propose vMIMO relaying scheme.
Effective gravitational couplings for cosmological perturbations in generalized Proca theories
De Felice, Antonio; Heisenberg, Lavinia; Kase, Ryotaro; Mukohyama, Shinji; Tsujikawa, Shinji; Zhang, Ying-li
2016-08-01
We consider the finite interactions of the generalized Proca theory including the sixth-order Lagrangian and derive the full linear perturbation equations of motion on the flat Friedmann-Lemaître-Robertson-Walker background in the presence of a matter perfect fluid. By construction, the propagating degrees of freedom (besides the matter perfect fluid) are two transverse vector perturbations, one longitudinal scalar, and two tensor polarizations. The Lagrangians associated with intrinsic vector modes neither affect the background equations of motion nor the second-order action of tensor perturbations, but they do give rise to nontrivial modifications to the no-ghost condition of vector perturbations and to the propagation speeds of vector and scalar perturbations. We derive the effective gravitational coupling Geff with matter density perturbations under a quasistatic approximation on scales deep inside the sound horizon. We find that the existence of intrinsic vector modes allows a possibility for reducing Geff. In fact, within the parameter space, Geff can be even smaller than the Newton gravitational constant G at the late cosmological epoch, with a peculiar phantom dark energy equation of state (without ghosts). The modifications to the slip parameter η and the evolution of the growth rate f σ8 are discussed as well. Thus, dark energy models in the framework of generalized Proca theories can be observationally distinguished from the Λ CDM model according to both cosmic growth and expansion history. Furthermore, we study the evolution of vector perturbations and show that outside the vector sound horizon the perturbations are nearly frozen and start to decay with oscillations after the horizon entry.
Joint Scheduling and ARQ for MU-MIMO Downlink in the Presence of Inter-Cell Interference
Shirani-Mehr, Hooman; Ramprashad, Sean A; Caire, Giuseppe
2010-01-01
User scheduling and multiuser multi-antenna (MU-MIMO) transmission are at the core of high rate data-oriented downlink schemes of the next-generation of cellular systems (e.g., LTE-Advanced). Scheduling selects groups of users according to their channels vector directions and SINR levels. However, when scheduling is applied independently in each cell, the inter-cell interference (ICI) power at each user receiver is not known in advance since it changes at each new scheduling slot depending on the scheduling decisions of all interfering base stations. In order to cope with this uncertainty, we consider the joint operation of scheduling, MU-MIMO beamforming and Automatic Repeat reQuest (ARQ). We develop a game-theoretic framework for this problem and build on stochastic optimization techniques in order to find optimal scheduling and ARQ schemes. Particularizing our framework to the case of "outage service rates", we obtain a scheme based on adaptive variable-rate coding at the physical layer, combined with ARQ ...
Directory of Open Access Journals (Sweden)
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.
Wolstenholme, E Œ
1978-01-01
Elementary Vectors, Third Edition serves as an introductory course in vector analysis and is intended to present the theoretical and application aspects of vectors. The book covers topics that rigorously explain and provide definitions, principles, equations, and methods in vector analysis. Applications of vector methods to simple kinematical and dynamical problems; central forces and orbits; and solutions to geometrical problems are discussed as well. This edition of the text also provides an appendix, intended for students, which the author hopes to bridge the gap between theory and appl
Large N Expansion. Vector Models
Nissimov, E; Nissimov, Emil; Pacheva, Svetlana
2006-01-01
Preliminary version of a contribution to the "Quantum Field Theory. Non-Perturbative QFT" topical area of "Modern Encyclopedia of Mathematical Physics" (SELECTA), eds. Aref'eva I, and Sternheimer D, Springer (2007). Consists of two parts - "main article" (Large N Expansion. Vector Models) and a "brief article" (BPHZL Renormalization).
Ashraphijuo, Mehdi; Aggarwal, Vaneet; Wang, Xiaodong
2012-01-01
In this paper, we study the effect of feedback on two-user MIMO interference channels. The capacity region of MIMO interference channels with feedback is characterized within a constant number of bits, where this constant is independent of the channel matrices. Further, it is shown that the capacity region of a MIMO interference channel with feedback and its reciprocal interference channel are within a constant number of bits. Finally, the generalized degrees of freedom region for the MIMO in...
Chiral Corrections to Vector Meson Decay Constants
Bijnens, J; Talavera, P; Bijnens, Johan; Gosdzinsky, Peter; Talavera, Pere
1998-01-01
We calculate the leading quark mass corrections of order $m_q\\log(m_q)$, $m_q$ and $m_q^{3/2}$ to the vector meson decay constants within Heavy Vector Meson Chiral Perturbation Theory. We discuss the issue of electromagnetic gauge invariance and the heavy mass expansion. Reasonably good fits to the observed decay constants are obtained.
Optimal Data Transmission on MIMO OFDM Channels
2008-12-01
ter facultado a possibilidade de enriquecer o meu conhecimento académico. Quando il mio maestro e mentore di tesi Roberto Cristi la ringrazio per la...environments. Some vectors do not present values in some indices , meaning that a particular or several modulations (rate ID) can not be employed. If
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。
Separate DOD and DOA Estimation for Bistatic MIMO Radar
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Lin Li
2016-01-01
Full Text Available A novel MUSIC-type algorithm is derived in this paper for the direction of departure (DOD and direction of arrival (DOA estimation in a bistatic MIMO radar. Through rearranging the received signal matrix, we illustrate that the DOD and the DOA can be separately estimated. Compared with conventional MUSIC-type algorithms, the proposed separate MUSIC algorithm can avoid the interference between DOD and DOA estimations effectively. Therefore, it is expected to give a better angle estimation performance and have a much lower computational complexity. Meanwhile, we demonstrate that our method is also effective for coherent targets in MIMO radar. Simulation results verify the efficiency of the proposed method, particularly when the signal-to-noise ratio (SNR is low and/or the number of snapshots is small.
Rateless Space Time Block Code for Massive MIMO Systems
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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.
Effective user selection algorithm for quantized precoding in massive MIMO
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Nayan fang
2015-02-01
Full Text Available The downlink of a multi-user massive MIMO wireless system is considered, where the base station equipped with a large number of antennas simultaneously servesmultiple users. In this paper, an effective user selection algorithm is proposed for quantized precoding in massive MIMO systems. The algorithm aims at minimizing the correlation of precoders among users by relaxing the optimal problem to be convex and solving it using the Primal Newton’s Barrier Method. The complexity of the proposed algorithm is relatively low and the performance shown by the numerical results is close to the exhaustive search method. The advantage of the proposed algorithm increasingly shows up as the transmit antennas increase significantly.
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.
Design and Verification of MIMO 2x2 Reference Antennas
DEFF Research Database (Denmark)
Szini, Istvan Janos; Pedersen, Gert Frølund; Estrada, J.
2012-01-01
The development and initial discussion of a reference MIMO 2×2 antenna concept has been presented in [1]. The reference antenna concept has been created to eliminate the uncertainties linked to the unknown antenna performance of the few LTE MIMO 2×2 reference devices or golden standards currently...... available for evaluating radiated data throughput measurement methodologies and test facilities. The proposed concept is based on simple antennas with a well-known Figure of Merit (FoM) and controllable performance. In this paper we present the recent developments on the antenna concept and report...... on the first measured performance at uniform incoming power distribution, figures and correlations between different measurement labs....
Novel Compact Multiband MIMO Antenna for Mobile Terminal
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Cheng Yang
2012-01-01
Full Text Available A novel compact MIMO antenna for personal digital assistant (PDA and pad computer is proposed. The proposed antenna is composed by two multipatch monopole antennas which are placed 90° apart for orthogonal radiation. To strengthen the isolation, a T-shaped ground branch with proper dimension is used to generate an additional coupling path to lower the mutual coupling (below −15 dB, especially at GSM850/900 band. The proposed MIMO antenna is fabricated and tested, both the simulated and the measured results are presented, and some parametric studies are also demonstrated. In addition, there are some advantages about the proposed antenna such as simple structure, easy fabrication, and low cost.
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.
On the Performance of Multiuser MIMO in UTRA FDD Uplink
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Wichman Risto
2004-01-01
Full Text Available We study the uplink performance of MIMO systems in UTRA FDD using noise rise and system load as performance measures. Results show that the uplink coverage and capacity of the UTRA FDD mode are significantly improved by SIMO and MIMO techniques that require only minor modifications to existing 3GPP specifications. Receive diversity in base station increases coverage and capacity in a straightforward manner, but the gain from transmit diversity in mobile station is small because of the fast closed-loop power control, which is essential to CDMA uplink performance. However, multiple transmit antennas in the mobile can be used to achieve higher than 2 Mbps single-user data rates.
Estimation of Sparse MIMO Channels with Common Support
Barbotin, Yann; Rangan, Sundeep; Vetterli, Martin
2011-01-01
We consider the problem of estimating sparse communication channels in the MIMO context. In small to medium bandwidth communications, as in the current standards for OFDM and CDMA communication systems (with bandwidth up to 20 MHz), such channels are individually sparse and at the same time share a common support set. Since the underlying physical channels are inherently continuous-time, we propose a parametric sparse estimation technique based on finite rate of innovation (FRI) principles. Parametric estimation is especially relevant to MIMO communications as it allows for a robust estimation and concise description of the channels. The core of the algorithm is a generalization of conventional spectral estimation methods to multiple input signals with common support. We show the application of our technique for channel estimation in OFDM (uniformly/contiguous DFT pilots) and CDMA downlink (Walsh-Hadamard coded schemes). In the presence of additive white Gaussian noise, theoretical lower bounds on the estimat...
Characteristic Equation of the Modified Smith predictor to MIMO Systems
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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.
SABA: A Testbed for a Real-Time MIMO System
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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.
Asymptotic analysis of multicell massive MIMO over Rician fading channels
Sanguinetti, Luca
2017-06-20
This work considers the downlink of a multicell massive MIMO system in which L base stations (BSs) of N antennas each communicate with K single-antenna user equipments randomly positioned in the coverage area. Within this setting, we are interested in evaluating the sum rate of the system when MRT and RZF are employed under the assumption that each intracell link forms a MIMO Rician uncorrelated fading channel. The analysis is conducted assuming that N and K grow large with a non-trivial ratio N/K under the assumption that the data transmission in each cell is affected by channel estimation errors, pilot contamination, and an arbitrary large scale attenuation. Numerical results are used to validate the asymptotic analysis in the finite system regime and to evaluate the network performance under different settings. The asymptotic results are also instrumental to get insights into the interplay among system parameters.
On the Compound MIMO Broadcast Channels with Confidential Messages
Kobayashi, Mari; Shamai, Shlomo; Debbah, Merouane
2009-01-01
We study the compound multi-input multi-output (MIMO) broadcast channel with confidential messages (BCC), where one transmitter sends a common message to two receivers and two confidential messages respectively to each receiver. The channel state may take one of a finite set of states, and the transmitter knows the state set but does not know the realization of the state. We study achievable rates with perfect secrecy in the high SNR regime by characterizing an achievable secrecy degree of freedom (s.d.o.f.) region for two models, the Gaussian MIMO-BCC and the ergodic fading multi-input single-output (MISO)-BCC without a common message. We show that by exploiting an additional temporal dimension due to state variation in the ergodic fading model, the achievable s.d.o.f. region can be significantly improved compared to the Gaussian model with a constant state, although at the price of a larger delay.
EVALUATION OF MIMO SYSTEM CAPACITY OVER RAYLEIGH FADING CHANNEL
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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
Advanced Signal Processing for MIMO-OFDM Receivers
DEFF Research Database (Denmark)
Manchón, Carles Navarro
This thesis deals with a wide range of topics within the research area of advanced baseband receiver design for wireless communication systems. In particular, the work focuses on signal processing algorithms for receivers in multiple-input multiple-output (MIMO) orthogonal frequency-division mult......This thesis deals with a wide range of topics within the research area of advanced baseband receiver design for wireless communication systems. In particular, the work focuses on signal processing algorithms for receivers in multiple-input multiple-output (MIMO) orthogonal frequency...... contributions is the derivation of a novel message-passing scheme combining the MF and BP frameworks; the algorithm is derived from the stationary points of a region-based free energy approximation, and is guaranteed to converge if the underlying probabilistic model satisfies certain conditions. Moreover, we...
Design and optimization of LTE 1800 MIMO antenna.
Wong, Huey Shin; Islam, Mohammad Tariqul; Kibria, Salehin
2014-01-01
A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide's outer shell. Isolation characteristics better than -15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz-1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi.
A MIMO-OFDM Testbed for Wireless Local Area Networks
Directory of Open Access Journals (Sweden)
Conrat Jean-Marc
2006-01-01
Full Text Available We describe the design steps and final implementation of a MIMO OFDM prototype platform developed to enhance the performance of wireless LAN standards such as HiperLAN/2 and 802.11, using multiple transmit and multiple receive antennas. We first describe the channel measurement campaign used to characterize the indoor operational propagation environment, and analyze the influence of the channel on code design through a ray-tracing channel simulator. We also comment on some antenna and RF issues which are of importance for the final realization of the testbed. Multiple coding, decoding, and channel estimation strategies are discussed and their respective performance-complexity trade-offs are evaluated over the realistic channel obtained from the propagation studies. Finally, we present the design methodology, including cross-validation of the Matlab, C++, and VHDL components, and the final demonstrator architecture. We highlight the increased measured performance of the MIMO testbed over the single-antenna system.
A MIMO-OFDM Testbed for Wireless Local Area Networks
Fàbregas, Albert Guilléni; Guillaud, Maxime; Slock, Dirk TM; Caire, Giuseppe; Gosse, Karine; Rouquette, Stéphanie; Dias, Alexandre Ribeiro; Bernardin, Philippe; Miet, Xavier; Conrat, Jean-Marc; Toutain, Yann; Peden, Alain; Li, Zaiqing
2006-12-01
We describe the design steps and final implementation of a MIMO OFDM prototype platform developed to enhance the performance of wireless LAN standards such as HiperLAN/2 and 802.11, using multiple transmit and multiple receive antennas. We first describe the channel measurement campaign used to characterize the indoor operational propagation environment, and analyze the influence of the channel on code design through a ray-tracing channel simulator. We also comment on some antenna and RF issues which are of importance for the final realization of the testbed. Multiple coding, decoding, and channel estimation strategies are discussed and their respective performance-complexity trade-offs are evaluated over the realistic channel obtained from the propagation studies. Finally, we present the design methodology, including cross-validation of the Matlab, C++, and VHDL components, and the final demonstrator architecture. We highlight the increased measured performance of the MIMO testbed over the single-antenna system.
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.
Primordial Perturbations in Einstein-Aether and BPSH Theories
Armendariz-Picon, Cristian; Garriga, Jaume
2010-01-01
We study the primordial perturbations generated during a stage of single-field inflation in Einstein-aether theories. Quantum fluctuations of the inflaton and aether fields seed long wavelength adiabatic and isocurvature scalar perturbations, as well as transverse vector perturbations. Geometrically, the isocurvature mode is the potential for the velocity field of the aether with respect to matter. For a certain range of parameters, this mode may lead to a sizable random velocity of the aether within the observable universe. The adiabatic mode corresponds to curvature perturbations of co-moving slices (where matter is at rest). In contrast with the standard case, it has a non-vanishing anisotropic stress on large scales. Scalar and vector perturbations may leave significant imprints on the cosmic microwave background. We calculate their primordial spectra, analyze their contributions to the temperature anisotropies, and formulate some of the phenomenological constraints that follow from observations. These ma...
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 ...
On the MIMO capacity with residual transceiver hardware impairments
Zhang, Xinlin; Matthaiou, Michail; Bjornson, Emil; Coldrey, Mikael; Debbah, Merouane
2014-01-01
International audience; —Radio-frequency (RF) impairments in the transceiver hardware of communication systems (e.g., phase noise (PN), high power amplifier (HPA) nonlinearities, or in-phase/quadrature-phase (I/Q) imbalance) can severely degrade the performance of traditional multiple-input multiple-output (MIMO) systems. Although calibration algorithms can partially compensate these impairments, the remaining distortion still has substantial impact. Despite this, most prior works have not an...
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
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...
MIMO scheme performance and detection in epsilon noise
Stepanov, Sander
2006-01-01
New approach for analysis and decoding MIMO signaling is developed for usual model of nongaussion noise consists of background and impulsive noise named epsilon - noise. It is shown that non-gaussion noise performance significantly worse than gaussion ones. Stimulation results strengthen out theory. Robust in statistical sense detection rule is suggested for such kind of noise features much best robust detector performance than detector designed for Gaussian noise in impulsive environment and...
Institute of Scientific and Technical Information of China (English)
张轶博
2004-01-01
多人多出(MIMO——multiple input multiple output)技术最早由Marconi于1908年提出，它利用多天线抑制信道衰落。MI．MO包括单人多出(SIMO single—unput multiple—output)系统和多人单出(MISO multiple—input single—output)系统。MIMO
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.
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.
Efficient collaborative sparse channel estimation in massive MIMO
Masood, Mudassir
2015-08-12
We propose a method for estimation of sparse frequency selective channels within MIMO-OFDM systems. These channels are independently sparse and share a common support. The method estimates the impulse response for each channel observed by the antennas at the receiver. Estimation is performed in a coordinated manner by sharing minimal information among neighboring antennas to achieve results better than many contemporary methods. Simulations demonstrate the superior performance of the proposed method.
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.
Statistical Mechanics Analysis of LDPC Coding in MIMO Gaussian Channels
Alamino, Roberto C.; Saad, David
2007-01-01
Using analytical methods of statistical mechanics, we analyse the typical behaviour of a multiple-input multiple-output (MIMO) Gaussian channel with binary inputs under LDPC network coding and joint decoding. The saddle point equations for the replica symmetric solution are found in particular realizations of this channel, including a small and large number of transmitters and receivers. In particular, we examine the cases of a single transmitter, a single receiver and the symmetric and asymm...
Hypersensitivity to Perturbations in the Quantum baker's Map
Schack, R
1999-01-01
We analyze a randomly perturbed quantum version of the baker's transformation, a prototype of an area-conserving chaotic map. By numerically simulating the perturbed evolution, we estimate the information needed to follow a perturbed Hilbert-space vector in time. We find that the Landauer erasure cost associated with this information grows very rapidly and becomes much larger than the maximum statistical entropy given by the logarithm of the dimension of Hilbert space. The quantum baker's map thus displays a hypersensitivity to perturbations that is analogous to behavior found earlier in the classical case. This hypersensitivity characterizes ``quantum chaos'' in a way that is directly relevant to statistical physics.
Brand, Louis
2006-01-01
The use of vectors not only simplifies treatments of differential geometry, mechanics, hydrodynamics, and electrodynamics, but also makes mathematical and physical concepts more tangible and easy to grasp. This text for undergraduates was designed as a short introductory course to give students the tools of vector algebra and calculus, as well as a brief glimpse into these subjects' manifold applications. The applications are developed to the extent that the uses of the potential function, both scalar and vector, are fully illustrated. Moreover, the basic postulates of vector analysis are brou
Analysis and Transceiver Design for the MIMO Broadcast Channel
Hunger, Raphael
2013-01-01
This book deals with the optimization-based joint design of the transmit and receive filters in MIMO broadcast channel in which the user terminals may be equipped with several antenna elements. Furthermore, the maximum performance of the system in the high power regime as well as the set of all feasible quality-of-service requirements is analyzed. First, a fundamental duality is derived that holds between the MIMO broadcast channel and virtual MIMO multiple access channel. This duality construct allows for the efficient solution of problems originally posed in the broadcast channel in the dual domain where a possibly hidden convexity can often be revealed. On the basis of the established duality result, the gradient-projection algorithm is introduced as a tool to solve constrained optimization problems to global optimality under certain conditions. The gradient-projection tool is then applied to solving the weighted sum rate maximization problem which is a central optimization that arises in any network u...
Hierarchical Interference Mitigation for Massive MIMO Cellular Networks
Liu, An; Lau, Vincent
2014-09-01
We propose a hierarchical interference mitigation scheme for massive MIMO cellular networks. The MIMO precoder at each base station (BS) is partitioned into an inner precoder and an outer precoder. The inner precoder controls the intra-cell interference and is adaptive to local channel state information (CSI) at each BS (CSIT). The outer precoder controls the inter-cell interference and is adaptive to channel statistics. Such hierarchical precoding structure reduces the number of pilot symbols required for CSI estimation in massive MIMO downlink and is robust to the backhaul latency. We study joint optimization of the outer precoders, the user selection, and the power allocation to maximize a general concave utility which has no closed-form expression. We first apply random matrix theory to obtain an approximated problem with closed-form objective. We show that the solution of the approximated problem is asymptotically optimal with respect to the original problem as the number of antennas per BS grows large. Then using the hidden convexity of the problem, we propose an iterative algorithm to find the optimal solution for the approximated problem. We also obtain a low complexity algorithm with provable convergence. Simulations show that the proposed design has significant gain over various state-of-the-art baselines.
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.
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.
Resource allocation and MIMO for 4G and beyond
2014-01-01
This book presents the underlying technological breakthroughs that allowed the current state of wireless technology development to evolve. The book focuses on the two lower layers of the ISO/OSI layered model, specifically the physical and data link layers including the media access control sub-layer. These two layers are of particular importance to wireless systems due to the spectrum shortage, the broadcast nature of interference, and time variability in the wireless channel. Topics covered in this book include: radio resource allocation (RRA) for emerging architectures such as Coordinated Multipoint (CoMP) and Device-to-Device communications (D2D); RRA for quality of service control; propagation and transceiver aspects of MIMO systems; and the design and selection of MIMO multiuser precoders. The proposed approaches for RRA and MIMO are applicable to mobile communication standards such as 3GPP’s LTE and LTE-Advanced, but also apply further to the continuously evolving wireless access technologies lan...
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.
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.
Investigations in Satellite MIMO Channel Modeling: Accent on Polarization
Directory of Open Access Journals (Sweden)
Péter Horváth
2007-05-01
Full Text Available Due to the much different environment in satellite and terrestrial links, possibilities in and design of MIMO systems are rather different as well. After pointing out these differences and problems arising from them, two MIMO designs are shown rather well adapted to satellite link characteristics. Cooperative diversity seems to be applicable; its concept is briefly presented without a detailed discussion, leaving solving particular satellite problems to later work. On the other hand, a detailed discussion of polarization time-coded diversity (PTC is given. A physical-statistical model for dual-polarized satellite links is presented together with measuring results validating the model. The concept of 3D polarization is presented as well as briefly describing compact 3D-polarized antennas known from the literature and applicable in satellite links. A synthetic satellite-to-indoor link is constructed and its electromagnetic behavior is simulated via the FDTD (finite-difference time-domain method. Previous result of the authors states that in 3D-PTC situations, MIMO capacity can be about two times higher than SIMO (single-input multiple-output capacity while a diversity gain of nearly 2ÃƒÂ—3 is further verified via extensive FDTD computer simulation.
Time-Domain Diversity in Ultra-Wideband MIMO Communications
Directory of Open Access Journals (Sweden)
Alain Sibille
2005-03-01
Full Text Available The development of ultra-wideband (UWB communications is impeded by the drastic transmitted power limitations imposed by regulation authorities due to the Ã¢Â€ÂœpollutingÃ¢Â€Â character of these radio emissions with respect to existing services. Technical solutions must be researched in order either to limit the level of spectral pollution by UWB devices or to increase their reception sensitivity. In the present work, we consider pulse-based modulations and investigate time-domain multiple-input multiple-output (MIMO diversity as one such possible solution. The basic principles of time-domain diversity in the extreme (low multipath density or intermediate (dense multipath UWB regimes are addressed, which predict the possibility of a MIMO gain equal to the product NtÃƒÂ—Nr of the numbers of transmit/receive antenna elements when the channel is not too severe. This analysis is confirmed by simulations using a parametric empirical stochastic double-directional channel model. They confirm the potential interest of MIMO approaches solutions in order to bring a valuable performance gain in UWB communications.
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.
Cognitive MIMO Frequency Diverse Array Radar with High LPI Performance
Directory of Open Access Journals (Sweden)
Ling Huang
2016-01-01
Full Text Available Frequency diverse array (FDA has its unique advantage in realizing low probability of intercept (LPI technology for its dependent beam pattern. In this paper, we proposed a cognitive radar based on the frequency diverse array multiple-input multiple-output (MIMO. To implement LPI of FDA MIMO transmit signals, a scheme for array weighting design is proposed, which is to minimize the energy of the target location and maximize the energy of the receiver. This is based on the range dependent characteristics of the frequency diverse array transmit beam pattern. To realize the objective problem, the algorithm is proposed as follows: the second-order nonconvex optimization problem is converted into a convex problem and solved by the bisection method and convex optimization. To get the information of target, the FDA MIMO radar is proposed to estimate the target parameters. Simulation results show that the proposed approach is effective in decreasing the detection probability of radar with lossless detection performance of the receive signal.
Measurement Matrix Design for Compressive Sensing Based MIMO Radar
Yu, Y; Poor, H V
2011-01-01
In colocated multiple-input multiple-output (MIMO) radar using compressive sensing (CS), a receive node compresses its received signal via a linear transformation, referred to as measurement matrix. The samples are subsequently forwarded to a fusion center, where an L1-optimization problem is formulated and solved for target information. CS-based MIMO radar exploits the target sparsity in the angle-Doppler-range space and thus achieves the high localization performance of traditional MIMO radar but with many fewer measurements. The measurement matrix is vital for CS recovery performance. This paper considers the design of measurement matrices that achieve an optimality criterion that depends on the coherence of the sensing matrix (CSM) and/or signal-to-interference ratio (SIR). The first approach minimizes a performance penalty that is a linear combination of CSM and the inverse SIR. The second one imposes a structure on the measurement matrix and determines the parameters involved so that the SIR is enhanced...
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.
Time-Division Multiuser MIMO with Statistical Feedback
Directory of Open Access Journals (Sweden)
Jia Chen
2008-02-01
Full Text Available This paper investigates a time-division multiuser multiple-input multiple-output (MIMO antenna system in K-block flat fading where users are given individual outage rate probability constraints and only one user accesses the channel at any given time slot (or block. Assuming a downlink channel and that the transmitter knows only the statistical information about the channel, our aim is to minimize the overall transmit power for achieving the users' outage constraint by jointly optimizing the power allocation and the time-sharing (i.e., the number of time slots of the users. This paper first derives the so-called minimum power equation (MPE to solve for the minimum transmit power required for attaining a given outage rate probability of a single-user MIMO block-fading channel if the number of blocks is predetermined. We then construct a convex optimization problem, which can mimic the original problem structure and permits to jointly consider the power consumption and the probability constraints of the users, to give a suboptimal multiuser time-sharing solution. This is finally combined with the MPE to provide a joint power allocation and time-sharing solution for the time-division multiuser MIMO system. Numerical results demonstrate that the proposed scheme performs nearly the same as the global optimum with inappreciable difference.
Robust MSE precoder for imperfectly known MIMO wireless correlated channel
Institute of Scientific and Technical Information of China (English)
MA Peng-fei; ZHAO Hui; WANG Wen-bo
2009-01-01
Aimed at that only one form of channel statistic information is utilized in traditional robust precoder schemes: either the channel mean or the transmit antenna correlation in multiple-input multiple-output (MIMO) wireless system, this paper proposes robust precoder designs which exploit both of statistic information to minimize the equalization mean-square error (MSE) with power constraint. Two different power constraints are studied. Besides the usual sum power constraint over all antennas, the per-antenna power constraint is imposed at transmitter in this paper. Since each antenna has its own amplifier, individual power constraint on each antenna is more realistic. Especially in MIMO-OFDM systems, the Peak-to-Average Ratio (PAR) is one of main practical problems. Simulations show that the proposed schemes have better performance than traditional normalized zero forcing schemes for imperfectly known correlated channel. Moreover, per-antenna power constraint can efficiently decrease the demand of dynamic range of power amplifier on each transmit antenna, especially in MIMO-OFDM systems.
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.
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.
Training sequence design for MIMO channels: an application-oriented approach
Katselis, D.; Rojas, C.R.; Bengtsson, M.; Bjornson, E.; Bombois, X.; Shariati, N.; Jansson, M.; Hjalmarsson, H.
2013-01-01
In this paper, the problem of training optimization for estimating a multiple-input multiple-output (MIMO) flat fading channel in the presence of spatially and temporally correlated Gaussian noise is studied in an application-oriented setup. So far, the problem of MIMO channel estimation has mostly
LTE Radiated Data Throughput Measurements, Adopting MIMO 2x2 Reference Antennas
DEFF Research Database (Denmark)
Szini, Istvan Janos; Pedersen, Gert Frølund; Barrio, Samantha Caporal Del;
2012-01-01
Long Term Evolution (LTE) requires Multiple Input Multiple Output (MIMO) antenna systems. Consequently a new over-the-air (OTA) test methodology need to be created to make proper assessment of LTE devices radiated performance. The antenna specific parameters i.e. total antenna efficiency, gain im...... performance, ruling out the LTE devices unknown MIMO 2x2 antenna performance....
User Influence on MIMO Channel Capacity for Handsets in Data Mode Operation
DEFF Research Database (Denmark)
Nielsen, Jesper Ødum; Yanakiev, Boyan Radkov; Bonev, Ivan Bonev;
2012-01-01
The current paper concerns realistic evaluation of the capacity of the MIMO channel between a BS and handheld device, such as a PDA or smartphone, held in front of the user’s body (data mode). The work is based on measurements of the MIMO channel between two widely separated BSs in a micro...
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.
Link, Ebe
2013-01-01
MIMO projekt 2010-2013: 2011. ja 2012. a. Eesti linnades toimunud rahvusvahelise muusikaloome alase koolitus- ja noorteprojekti MIMO (Moving in! Moving on!) raames toimunust. Viljandi Kultuuriakadeemia tudengite töötubadest Eesti väikelinnade koolides ja noortekeskustes. Noorte poolt antud tagasisidest töötubadele
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...
DFT based spatial multiplexing and maximum ratio transmission for mm-wawe large MIMO
DEFF Research Database (Denmark)
Phan-Huy, D.-T.; Tölli, A.; Rajatheva, N.;
2014-01-01
By using large point-to-point multiple input multiple output (MIMO), spatial multiplexing of a large number of data streams in wireless communications using millimeter-waves (mm-waves) can be achieved. However, according to the antenna spacing and transmitter-receiver distance, the MIMO channel...
Zero-Forcing Pre-coding for MIMO WiMAX Transceivers
DEFF Research Database (Denmark)
Cattoni, Andrea Fabio; Le Moullec, Yannick; Sacchi, Claudio
2013-01-01
Next generation wireless communication networks are expected to achieve ever increasing data rates. Multi-User Multiple-Input-Multiple-Output (MU-MIMO) is a key technique to obtain the expected performance, because such a technique combines the high capacity achievable using MIMO channel with the...
DEFF Research Database (Denmark)
Zhang, Shuai; Zhao, Kun; Ying, Zhinong
2015-01-01
A diagonal antenna-chassis mode is investigated in long-term evolution multiple-input-multiple-output (LTE MIMO) antennas. The MIMO bandwidth is defined in this paper as the overlap range of the low-envelope correlation coefficient, high total efficiency, and -6-dB impedance matching bandwidths...
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...
Link, Ebe
2013-01-01
MIMO projekt 2010-2013: 2011. ja 2012. a. Eesti linnades toimunud rahvusvahelise muusikaloome alase koolitus- ja noorteprojekti MIMO (Moving in! Moving on!) raames toimunust. Viljandi Kultuuriakadeemia tudengite töötubadest Eesti väikelinnade koolides ja noortekeskustes. Noorte poolt antud tagasisidest töötubadele
Automated Lattice Perturbation Theory
Energy Technology Data Exchange (ETDEWEB)
Monahan, Christopher
2014-11-01
I review recent developments in automated lattice perturbation theory. Starting with an overview of lattice perturbation theory, I focus on the three automation packages currently "on the market": HiPPy/HPsrc, Pastor and PhySyCAl. I highlight some recent applications of these methods, particularly in B physics. In the final section I briefly discuss the related, but distinct, approach of numerical stochastic perturbation theory.
Generalized Supersymmetric Perturbation Theory
Institute of Scientific and Technical Information of China (English)
B. G(o)n(ǖ)l
2004-01-01
@@ Using the basic ingredient of supersymmetry, a simple alternative approach is developed to perturbation theory in one-dimensional non-relativistic quantum mechanics. The formulae for the energy shifts and wavefunctions do not involve tedious calculations which appear in the available perturbation theories. The model applicable in the same form to both the ground state and excited bound states, unlike the recently introduced supersymmetric perturbation technique which, together with other approaches based on logarithmic perturbation theory, are involved within the more general framework of the present formalism.
Density matrix perturbation theory.
Niklasson, Anders M N; Challacombe, Matt
2004-05-14
An orbital-free quantum perturbation theory is proposed. It gives the response of the density matrix upon variation of the Hamiltonian by quadratically convergent recursions based on perturbed projections. The technique allows treatment of embedded quantum subsystems with a computational cost scaling linearly with the size of the perturbed region, O(N(pert.)), and as O(1) with the total system size. The method allows efficient high order perturbation expansions, as demonstrated with an example involving a 10th order expansion. Density matrix analogs of Wigner's 2n+1 rule are also presented.
Experimental investigation of a dual-band handset MIMO antenna using a spatial fading emulator
DEFF Research Database (Denmark)
Sakata, Tsutomu; Yamamoto, Atsushi; Hayashi, Toshiteru
2010-01-01
An experimental investigation of handset MIMO antennas with dual-band operation was performed using the data from a radio propagation test in an urban area of Aalborg city in Denmark and an over-the-air test using a spatial fading emulator. It is concluded from the agreement between MIMO characte......An experimental investigation of handset MIMO antennas with dual-band operation was performed using the data from a radio propagation test in an urban area of Aalborg city in Denmark and an over-the-air test using a spatial fading emulator. It is concluded from the agreement between MIMO...... characteristics of the both measurements that the emulator is effective in evaluating handset MIMO arrays in the case of a multipath fading environment with one spatial cluster at 776 MHz and 2.35 GHz....
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.
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.
Perturbations of Kantowski-Sachs models
Bradley, Michael; Keresztes, Zoltán; Gergely, László Á; Dunsby, Peter K S
2013-01-01
Perturbations of Kantowski-Sachs models with a positive cosmological constant are considered in a harmonic decomposition, in the framework of gauge invariant 1+3 and 1+1+2 covariant splits of spacetime. Scalar, vector and tensor modes are allowed, however they remain vorticity-free and of perfect fluid type. The dynamics is encompassed in six evolution equations for six harmonic coefficients.
阿德利亚产品与MIMO-OFDM无线宽带技术%Azalea Products and MIMO-OFDM Wireless Broadband Technology
Institute of Scientific and Technical Information of China (English)
阿德利亚科技
2005-01-01
@@ 1.MIMO-OFD M技术介绍 正交频分复用(OFDM)是在无线高速数据传输中常用的一种技术.OFDM可以利用设备的多天线结构在一个时变的多径衰落信道中提高分集增益和系统容量,这促成了MIMO-OFDM系统的出现.
Perturbative Topological Field Theory
Dijkgraaf, Robbert
We give a review of the application of perturbative techniques to topological quantum field theories, in particular three-dimensional Chern-Simons-Witten theory and its various generalizations. To this end we give an introduction to graph homology and homotopy algebras and the work of Vassiliev and Kontsevich on perturbative knot invariants.
Perturbing supersymmetric black hole
Onozawa, H; Mishima, T; Ishihara, H; Onozawa, Hisashi; Okamura, Takashi; Mishima, Takashi; Ishihara, Hideki
1996-01-01
An investigation of the perturbations of the Reissner-Nordstr\\"{o}m black hole in the N=2 supergravity is presented. In the extreme case, the black hole responds to the perturbation of each field in the same manner. This is possibly because we can match the modes of the graviton, gravitino, and photon using supersymmetry transformations.
Gaugeon Formalism for Perturbative Quantum Gravity
Upadhyay, Sudhaker
2014-01-01
In this paper we investigate the Yokoyama gaugeon formalism for perturbative quantum gravity in general curved spacetime. Within the gaugeon formalism, we extend the configuration space by introducing vector gaugeon fields describing quantum gauge freedom. Such extended theory of perturbative gravity admits quantum gauge transformations leading to an natural shift in the gauge parameter. Further we impose the Gupta-Bleuler type subsidiary condition to remove the unphysical gaugeon modes. To replace the Gupta-Bleuler type condition by more acceptable Kugo-Ojima type subsidiary condition we analyse the BRST symmetric gaugeon formalism. Further, the physical Hilbert space is constructed for the perturbative quantum gravity which remains invariant under both the BRST symmetry and quantum gauge transformations.
Cosmological Perturbations in Extended Massive Gravity
Gumrukcuoglu, A Emir; Lin, Chunshan; Mukohyama, Shinji; Trodden, Mark
2013-01-01
We study cosmological perturbations around self-accelerating solutions to two extensions of nonlinear massive gravity: the quasi-dilaton theory and the mass-varying theory. We examine stability of the cosmological solutions, and the extent to which the vanishing of the kinetic terms for scalar and vector perturbations of self-accelerating solutions in massive gravity is generic when the theory is extended. We find that these kinetic terms are in general non-vanishing in both extensions, though there are constraints on the parameters and background evolution from demanding that they have the correct sign. In particular, the self-accelerating solutions of the quasi-dilaton theory are always unstable to scalar perturbations with wavelength shorter than the Hubble length.
Frame independent cosmological perturbations
Energy Technology Data Exchange (ETDEWEB)
Prokopec, Tomislav; Weenink, Jan, E-mail: t.prokopec@uu.nl, E-mail: j.g.weenink@uu.nl [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, 3585 CE Utrecht (Netherlands)
2013-09-01
We compute the third order gauge invariant action for scalar-graviton interactions in the Jordan frame. We demonstrate that the gauge invariant action for scalar and tensor perturbations on one physical hypersurface only differs from that on another physical hypersurface via terms proportional to the equation of motion and boundary terms, such that the evolution of non-Gaussianity may be called unique. Moreover, we demonstrate that the gauge invariant curvature perturbation and graviton on uniform field hypersurfaces in the Jordan frame are equal to their counterparts in the Einstein frame. These frame independent perturbations are therefore particularly useful in relating results in different frames at the perturbative level. On the other hand, the field perturbation and graviton on uniform curvature hypersurfaces in the Jordan and Einstein frame are non-linearly related, as are their corresponding actions and n-point functions.
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.
Max-min SINR low complexity transceiver design for single cell massive MIMO
Sifaou, Houssem
2016-08-11
This work focuses on large scale multi-user MIMO systems in which the base station (BS) outfitted with M antennas communicates with K single antenna user equipments (UEs). In particular, we aim at designing the linear precoder and receiver that maximizes the minimum signal-to-interference-plus-noise ratio (SINR) subject to a given power constraint. To gain insights into the structure of the optimal precoder and receiver as well as to reduce the computational complexity for their implementation, we analyze the asymptotic regime where M and K grow large with a given ratio and make use of random matrix theory (RMT) tools to compute accurate approximations. Although simpler, the implementation of the asymptotic precoder and receiver requires fast inversions of large matrices in every coherence period. To overcome this issue, we apply the truncated polynomial expansion (TPE) technique to the precoding and receiving vector of each UE and make use of RMT to determine the optimal weighting coefficients that asymptotically solve the max-min SINR problem. Numerical results are used to show that the proposed TPE-based precoder and receiver almost achieve the same performance as the optimal ones while requiring a lower complexity.
Guilfoyle, R.A.; Smith, L.M.
1994-12-27
A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.
Guilfoyle, Richard A.; Smith, Lloyd M.
1994-01-01
A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.
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.
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.
MIMO-radar Waveform Covariance Matrices for High SINR and Low Side-lobe Levels
Ahmed, Sajid
2012-12-29
MIMO-radar has better parametric identifiability but compared to phased-array radar it shows loss in signal-to-noise ratio due to non-coherent processing. To exploit the benefits of both MIMO-radar and phased-array two transmit covariance matrices are found. Both of the covariance matrices yield gain in signal-to-interference-plus-noise ratio (SINR) compared to MIMO-radar and have lower side-lobe levels (SLL)\\'s compared to phased-array and MIMO-radar. Moreover, in contrast to recently introduced phased-MIMO scheme, where each antenna transmit different power, our proposed schemes allows same power transmission from each antenna. The SLL\\'s of the proposed first covariance matrix are higher than the phased-MIMO scheme while the SLL\\'s of the second proposed covariance matrix are lower than the phased-MIMO scheme. The first covariance matrix is generated using an auto-regressive process, which allow us to change the SINR and side lobe levels by changing the auto-regressive parameter, while to generate the second covariance matrix the values of sine function between 0 and $\\\\pi$ with the step size of $\\\\pi/n_T$ are used to form a positive-semidefinite Toeplitiz matrix, where $n_T$ is the number of transmit antennas. Simulation results validate our analytical results.
Rong, Shu-Jun; Liu, Qiu-Yu
2012-04-01
The puma model on the basis of the Lorentz and CPT violation may bring an economical interpretation to the conventional neutrinos oscillation and part of the anomalous oscillations. We study the effect of the perturbation to the puma model. In the case of the first-order perturbation which keeps the (23) interchange symmetry, the mixing matrix element Ue3 is always zero. The nonzero mixing matrix element Ue3 is obtained in the second-order perturbation that breaks the (23) interchange symmetry.
Four-Dimensional Spin Foam Perturbation Theory
Directory of Open Access Journals (Sweden)
João Faria Martins
2011-10-01
Full Text Available We define a four-dimensional spin-foam perturbation theory for the BF-theory with a B∧B potential term defined for a compact semi-simple Lie group G on a compact orientable 4-manifold M. This is done by using the formal spin foam perturbative series coming from the spin-foam generating functional. We then regularize the terms in the perturbative series by passing to the category of representations of the quantum group U_q(g where g is the Lie algebra of G and q is a root of unity. The Chain-Mail formalism can be used to calculate the perturbative terms when the vector space of intertwiners Λ⊗Λ→A, where A is the adjoint representation of g, is 1-dimensional for each irrep Λ. We calculate the partition function Z in the dilute-gas limit for a special class of triangulations of restricted local complexity, which we conjecture to exist on any 4-manifold M. We prove that the first-order perturbative contribution vanishes for finite triangulations, so that we define a dilute-gas limit by using the second-order contribution. We show that Z is an analytic continuation of the Crane-Yetter partition function. Furthermore, we relate Z to the partition function for the F∧F theory.
Upper Hölder continuity of parametric vector optimization problems
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Xian-Fu Hu
2016-11-01
Full Text Available Abstract This paper is concerned with upper Hölder continuity and Hölder calmness of a perturbed vector optimization problem. We establish some new sufficient conditions for upper Hölder continuity and Hölder calmness of the perturbed solution mappings and the perturbed optimal value mappings of a vector optimization problem under the case that the objective function and the feasible set are, respectively, perturbed by parameters. Our results generalize and extend the corresponding ones of Li and Li (Appl. Math. Comput. 232:908-918, 2014.
Perturbations of planar algebras
Das, Paramita; Gupta, Ved Prakash
2010-01-01
We introduce the concept of {\\em weight} of a planar algebra $P$ and construct a new planar algebra referred as the {\\em perturbation of $P$} by the weight. We establish a one-to-one correspondence between pivotal structures on 2-categories and perturbations of planar algebras by weights. To each bifinite bimodule over $II_1$-factors, we associate a {\\em bimodule planar algebra} bimodule corresponds naturally with sphericality of the bimodule planar algebra. As a consequence of this, we reproduce an extension of Jones' theorem (of associating 'subfactor planar algebras' to extremal subfactors). Conversely, given a bimodule planar algebra, we construct a bifinite bimodule whose associated bimodule planar algebra is the one which we start with using perturbations and Jones-Walker-Shlyakhtenko-Kodiyalam-Sunder method of reconstructing an extremal subfactor from a subfactor planar algebra. We show that the perturbation class of a bimodule planar algebra contains a unique spherical unimodular bimodule planar algeb...
Introduction to perturbation techniques
Nayfeh, Ali H
2011-01-01
Similarities, differences, advantages and limitations of perturbation techniques are pointed out concisely. The techniques are described by means of examples that consist mainly of algebraic and ordinary differential equations. Each chapter contains a number of exercises.
MIMO OTA Testing in Small Multi-Probe Anechoic Chamber Setups
DEFF Research Database (Denmark)
Llorente, Ines Carton; Fan, Wei; Pedersen, Gert F.
2016-01-01
OTA testing of MIMO capable terminals is often performed in large anechoic chambers, where planar waves impinging the test area are assumed. Furthermore, reflections from the chamber, and probe coupling are often considered negligible due to the large dimensions of the chamber. This paper...... investigates the feasibility of reducing the physical dimension of 2D multi-probe anechoic chamber setups for MIMO OTA testing, with the purpose of reducing the cost and space of the setup. In the paper, a channel emulation algorithm and chamber compensation technique are proposed for MIMO OTA testing in small...
Directory of Open Access Journals (Sweden)
Xia Liu
2010-01-01
Full Text Available This paper reports investigations on the effect of antenna mutual coupling on performance of training-based Multiple-Input Multiple-Output (MIMO channel estimation. The influence of mutual coupling is assessed for two training-based channel estimation methods, Scaled Least Square (SLS and Minimum Mean Square Error (MMSE. It is shown that the accuracy of MIMO channel estimation is governed by the sum of eigenvalues of channel correlation matrix which in turn is influenced by the mutual coupling in transmitting and receiving array antennas. A water-filling-based procedure is proposed to optimize the training signal transmission to minimize the MIMO channel estimation errors.
Reduction of snapshots for MIMO radar detection by block/group orthogonal matching pursuit
Ali, Hussain El Hosiny
2014-10-01
Multiple-input multiple-output (MIMO) radar works on the principle of transmission of independent waveforms at each element of its antenna array and is widely used for surveillance purposes. In this work, we investigate MIMO radar target localization problem with compressive sensing. Specifically, we try to solve the problem of estimation of target location in MIMO radar by group and block sparsity algorithms. It will lead us to a reduced number of snapshots required and also we can achieve better radar resolution. We will use group orthogonal matching pursuit (GOMP) and block orthogonal matching pursuit (BOMP) for our problem. © 2014 IEEE.
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...
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.
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.
Simplified 3D Fading Channels Adopted in MIMO Beamforming Schemes
Institute of Scientific and Technical Information of China (English)
Joy Iong-Zong Chen; Bo Huei Lee
2015-01-01
A simplified three-dimension (3D) fading channel model deployed in a multi-input multi-output (MIMO) beamforming system is explored in this article. Both angle of arrival (AoA) and angle of departure (AoD) which impact the overall system performance are examined. The numerical results are given for validating the accuracy of the theoretical derived formulas. Furthermore, the performances of the model with different number of transmitters and receivers are studied and compared. The increment in AoA parameters definitely generates the impact of the system performance when the consideration of simplified 3D channels.
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...
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.
Robust Transceiver Design for Multiuser MIMO Downlink with Channel Uncertainties
Miao, Wei; Li, Yunzhou; Chen, Xiang; Zhou, Shidong; Wang, Jing
This letter addresses the problem of robust transceiver design for the multiuser multiple-input-multiple-output (MIMO) downlink where the channel state information at the base station (BS) is imperfect. A stochastic approach which minimizes the expectation of the total mean square error (MSE) of the downlink conditioned on the channel estimates under a total transmit power constraint is adopted. The iterative algorithm reported in [2] is improved to handle the proposed robust optimization problem. Simulation results show that our proposed robust scheme effectively reduces the performance loss due to channel uncertainties and outperforms existing methods, especially when the channel errors of the users are different.
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 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).
MIMO capacity for deterministic channel models: sublinear growth
DEFF Research Database (Denmark)
Bentosela, Francois; Cornean, Horia; Marchetti, Nicola
2013-01-01
This is the second paper by the authors in a series concerned with the development of a deterministic model for the transfer matrix of a MIMO system. In our previous paper, we started from the Maxwell equations and described the generic structure of such a deterministic transfer matrix...... some generic assumptions, we prove that the capacity grows much more slowly than linearly with the number of antennas. These results reinforce previous heuristic results obtained from statistical models of the transfer matrix, which also predict a sublinear behavior....
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.
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
Diversity Order Results for MIMO Optical Wireless Communications
Sapenov, Yerzhan
2017-09-21
An optical wireless multiple-input multiple-output (MIMO) communication system employing intensity-modulation direct-detection (IM/DD) is considered. The maximal diversity order of the channel is characterized by studying the outage probability. Then, spatial repetition coding (RC) is shown to be diversity-optimal as it achieves the channel’s maximal diversity order. This diversity order is given by a simple expression which is suitable for any channel statistics of practical interest. The results are specialized to some practical channel statistics, and numerical results are provided to verify the results.
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.
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.
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.
Planar MIMO Antenna with Slits for WBAN Applications
Directory of Open Access Journals (Sweden)
Do-Gu Kang
2014-01-01
Full Text Available A planar MIMO antenna with slits for WBAN applications is proposed. The antenna consists of two PIFAs, ground pads, and two slits. By adding ground pads, the antenna size is reduced with improved impedance matching. Through two slits in a ground plane, the isolation characteristic is improved and the resonant frequency can be controlled. To analyze the antenna performance on a human body, the proposed antenna on a human equivalent flat phantom is investigated through simulations. Regardless of the existence of the phantom, the antenna operates in 2.4 GHz ISM band with the isolation higher than 18 dB.
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.
Baseband receiver design for wireless MIMO-OFDM communications
Chiueh, Tzi-Dar; Lai I-Wei; Chiueh, Tzi-Dar
2012-01-01
The Second Edition of OFDM Baseband Receiver Design for Wirless Communications, this book expands on the earlier edition with enhanced coverage of MIMO techniques, additional baseband algorithms, and more IC design examples. The authors cover the full range of OFDM technology, from theories and algorithms to architectures and circuits. The book gives a concise yet comprehensive look at digital communication fundamentals before explaining signal processing algorithms in receivers. The authors give detailed treatment of hardware issues - from architecture to IC implementation. Links OFDM and M.
Perturbations around black holes
Wang, B
2005-01-01
Perturbations around black holes have been an intriguing topic in the last few decades. They are particularly important today, since they relate to the gravitational wave observations which may provide the unique fingerprint of black holes' existence. Besides the astrophysical interest, theoretically perturbations around black holes can be used as testing grounds to examine the proposed AdS/CFT and dS/CFT correspondence.
Perturbations and quantum relaxation
Kandhadai, Adithya
2016-01-01
We investigate whether small perturbations can cause relaxation to quantum equilibrium over very long timescales. We consider in particular a two-dimensional harmonic oscillator, which can serve as a model of a field mode on expanding space. We assume an initial wave function with small perturbations to the ground state. We present evidence that the trajectories are highly confined so as to preclude relaxation to equilibrium even over very long timescales. Cosmological implications are briefly discussed.
Perturbations of Kantowski-Sachs models with a cosmological constant
Keresztes, Zoltán; Bradley, Michael; Dunsby, Peter K S; Gergely, László Á
2013-01-01
We investigate perturbations of Kantowski-Sachs models with a positive cosmological constant, using the gauge invariant 1+3 and 1+1+2 covariant splits of spacetime together with a harmonic decomposition. The perturbations are assumed to be vorticity-free and of perfect fluid type, but otherwise include general scalar, vector and tensor modes. In this case the set of equations can be reduced to six evolution equations for six harmonic coefficients.
Cosmological perturbations in massive gravity with doubly coupled matter
Gümrükçüoğlu, A Emir; Mukohyama, Shinji
2014-01-01
We investigate the cosmological perturbations around FLRW solutions to non- linear massive gravity with a new effective coupling to matter proposed recently. Unlike the case with minimal matter coupling, all five degrees of freedom in the gravity sector propagate on generic self-accelerating FLRW backgrounds. We study the stability of the cosmological solutions and put constraints on the parameters of the theory by demanding the correct sign for the kinetic terms for scalar, vector and tensor perturbations.
Cosmological perturbations in massive gravity with doubly coupled matter
Gümrükçüoğlu, A. Emir; Heisenberg, Lavinia; Mukohyama, Shinji
2015-02-01
We investigate the cosmological perturbations around FLRW solutions to non- linear massive gravity with a new effective coupling to matter proposed recently. Unlike the case with minimal matter coupling, all five degrees of freedom in the gravity sector propagate on generic self-accelerating FLRW backgrounds. We study the stability of the cosmological solutions and put constraints on the parameters of the theory by demanding the correct sign for the kinetic terms for scalar, vector and tensor perturbations.
Process for computing geometric perturbations for probabilistic analysis
Fitch, Simeon H. K. [Charlottesville, VA; Riha, David S [San Antonio, TX; Thacker, Ben H [San Antonio, TX
2012-04-10
A method for computing geometric perturbations for probabilistic analysis. The probabilistic analysis is based on finite element modeling, in which uncertainties in the modeled system are represented by changes in the nominal geometry of the model, referred to as "perturbations". These changes are accomplished using displacement vectors, which are computed for each node of a region of interest and are based on mean-value coordinate calculations.
Institute of Scientific and Technical Information of China (English)
RONG Shu-Jun; LIU Qiu-Yu
2012-01-01
The puma model on the basis of the Lorentz and CPT violation may bring an economical interpretation to the conventional neutrinos oscillation and part of the anomalous oscillations.We study the effect of the perturbation to the puma model.In the case of the first-order perturbation which keeps the (23) interchange symmetry,the mixing matrix element Ue3 is always zero.The nonzero mixing matrix element Ue3 is obtained in the second-order perturbation that breaks the (23) interchange symmetry.%The puma model on the basis of the Lorentz and CPT violation may bring an economical interpretation to the conventional neutrinos oscillation and part of the anomalous oscillations. We study the effect of the perturbation to the puma model. In the case of the first-order perturbation which keeps the (23) interchange symmetry, the mixing matrix element Ue3 is always zero. The nonzero mixing matrix element Ue3 is obtained in the second-order perturbation that breaks the (23) interchange symmetry.
Hyperon decay form factors in chiral perturbation theory
Lacour, Andre; Meißner, Ulf-G
2007-01-01
We present a complete calculation of the SU(3)-breaking corrections to the hyperon vector form factors up to O(p^4) in covariant baryon chiral perturbation theory. Partial higher-order contributions are obtained, and we discuss chiral extrapolations of the vector form factor at zero momentum transfer. In addition we derive low-energy theorems for the subleading moments in hyperon decays, the weak Dirac radii and the weak anomalous magnetic moments, up to O(p^4).
Perturbative neutrino pair creation by an external source
Koers, H
2004-01-01
We consider the rate of fermion-antifermion pair creation by an external field. We derive a rate formula that is valid for a coupling with arbitrary vector and axial vector components to first order in perturbation theory. This is then applied to study the creation of neutrinos by nuclear matter, a problem with astrophysical relevance. We present an estimate for the creation rate per unit volume, compare this to previous results and comment on the role of the neutrino mass.
Robinson, Gilbert de B
2011-01-01
This brief undergraduate-level text by a prominent Cambridge-educated mathematician explores the relationship between algebra and geometry. An elementary course in plane geometry is the sole requirement for Gilbert de B. Robinson's text, which is the result of several years of teaching and learning the most effective methods from discussions with students. Topics include lines and planes, determinants and linear equations, matrices, groups and linear transformations, and vectors and vector spaces. Additional subjects range from conics and quadrics to homogeneous coordinates and projective geom
Efficient Coordinated Recovery of Sparse Channels in Massive MIMO
Masood, Mudassir; Afify, Laila H.; Al-Naffouri, Tareq Y.
2015-01-01
This paper addresses the problem of estimating sparse channels in massive MIMO-OFDM systems. Most wireless channels are sparse in nature with large delay spread. In addition, these channels as observed by multiple antennas in a neighborhood have approximately common support. The sparsity and common support properties are attractive when it comes to the efficient estimation of large number of channels in massive MIMO systems. Moreover, to avoid pilot contamination and to achieve better spectral efficiency, it is important to use a small number of pilots. We present a novel channel estimation approach which utilizes the sparsity and common support properties to estimate sparse channels and require a small number of pilots. Two algorithms based on this approach have been developed which perform Bayesian estimates of sparse channels even when the prior is non-Gaussian or unknown. Neighboring antennas share among each other their beliefs about the locations of active channel taps to perform estimation. The coordinated approach improves channel estimates and also reduces the required number of pilots. Further improvement is achieved by the data-aided version of the algorithm. Extensive simulation results are provided to demonstrate the performance of the proposed algorithms.
MIMO Antenna with High Isolation for WBAN Applications
Directory of Open Access Journals (Sweden)
Do-Gu Kang
2015-01-01
Full Text Available A multi-input multi-output (MIMO antenna with high isolation is proposed for 2.4 GHz ISM band (2.4–2.485 GHz WBAN applications. The proposed MIMO antenna consists of two PIFA elements and utilizes an isolator composed of a shorted strip and two slits in the ground plane. Although the separation between the two PIFAs is minimized to 8 mm (0.06 λ∘, isolation performance is improved by virtue of an isolator. To analyze the antenna’s performance on a human body, the proposed antenna is placed on a human muscle-equivalent flat phantom and is investigated through simulations. The measured −10 dB reflection coefficient bandwidth of the antenna ranges from 2.11 GHz to 2.6 GHz, and the isolation is lower than −38 dB over the 2.4 GHz ISM band.
Feedback Reduction in Uplink MIMO OFDM Systems by Chunk Optimization
Directory of Open Access Journals (Sweden)
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.
Statistical Angular Resolution Limit for Ultrawideband MIMO Noise Radar
Directory of Open Access Journals (Sweden)
Xiaoli Zhou
2015-01-01
Full Text Available The two-dimensional angular resolution limit (ARL of elevation and azimuth for MIMO radar with ultrawideband (UWB noise waveforms is investigated using statistical resolution theory. First, the signal model of monostatic UWB MIMO noise radar is established in a 3D reference frame. Then, the statistical angular resolution limits (SARLs of two closely spaced targets are derived using the detection-theoretic and estimation-theoretic approaches, respectively. The detection-theoretic approach is based on the generalized likelihood ratio test (GLRT with given probabilities of false alarm and detection, while the estimation-theoretic approach is based on Smith’s criterion which involves the Cramér-Rao lower bound (CRLB. Furthermore, the relationship between the two approaches is presented, and the factors affecting the SARL, that is, detection parameters, transmit waveforms, array geometry, signal-to-noise ratio (SNR, and parameters of target (i.e., radar cross section (RCS and direction, are analyzed. Compared with the conventional radar resolution theory defined by the ambiguity function, the SARL reflects the practical resolution ability of radar and can provide an optimization criterion for radar system design.
Validation of a MIMO Random Control Tool Using the CUBE™
Carrella, Alex; Janssens, Joris; Debille, Jan; Faignet, Eddy; Peetrs, Bart
2012-07-01
Environmental testing is an important engineering discipline which aims at simulating the effect of the environmnet on a given structure, item or system. A particular environment is the vibratory one. From development to qualification, engineering systems subject to harsh dynamic environments have to be tested in order to ensure their capability to withstand vibrations. To this end, there exist a wealth of test stadards which impose strict pass/fail criteria. However, these methods are rather dated and the testing community is constantly striving to update the standards to account for new technologies and ever more stringent requirements. Currently, the standard specify to carry out vibration tests along one axis at the time, that is using a Single-Input-Single-Ouput (SISO) or a Single-Input- Multiple-Ouput (SIMO) approach. However, there are a number of significant advanteges in using a Multiple- Input-Multiple-Ouput (MIMO) apporach. In this paper are presented the results of an experimental campaign aimed at assessing the capabilty of the new MIMO Random control developed at LMS.
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.
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...
Information-theoretic analysis of MIMO channel sounding
Baum, Daniel S
2007-01-01
The large majority of commercially available multiple-input multiple-output (MIMO) radio channel measurement devices (sounders) is based on time-division multiplexed switching (TDMS) of a single transmit/receive radio-frequency chain into the elements of a transmit/receive antenna array. While being cost-effective, such a solution can cause significant measurement errors due to phase noise and frequency offset in the local oscillators. In this paper, we systematically analyze the resulting errors and show that, in practice, overestimation of channel capacity by several hundred percent can occur. Overestimation is caused by phase noise (and to a lesser extent frequency offset) leading to an increase of the MIMO channel rank. Our analysis furthermore reveals that the impact of phase errors is, in general, most pronounced if the physical channel has low rank (typical for line-of-sight or poor scattering scenarios). The extreme case of a rank-1 physical channel is analyzed in detail. Finally, we present measureme...
MIMO Terminal Performance Evaluation with a Novel Wireless Cable Method
DEFF Research Database (Denmark)
Fan, Wei; Kyösti, Pekka; Hentilä, Lassi
2017-01-01
Conventional conductive method, where antennas on the device under test (DUT) are disconnected from antenna ports and replaced with radio frequency (RF) coaxial cables, has been dominantly utilized in industry to evaluate multiple-input multiple-output (MIMO) capable terminals. However, direct RF...... emulator output ports, a wireless cable connection can be achieved. The proposed method can be executed in a small RF shielded anechoic box, and offers low system cost, high measurement reliability and repeatability.......Conventional conductive method, where antennas on the device under test (DUT) are disconnected from antenna ports and replaced with radio frequency (RF) coaxial cables, has been dominantly utilized in industry to evaluate multiple-input multiple-output (MIMO) capable terminals. However, direct RF...... cable connection introduces many practical problems and a radiated method to replace cable connection is highly desirable. Existing wireless cable method relies on the knowledge of a transfer matrix between the channel emulator (CE) output ports and DUT antenna ports, and also requires an anechoic...
Antenna-User Interaction in MIMO-Enabled Laptops
Directory of Open Access Journals (Sweden)
Y. Rahmat-Samii
2009-12-01
Full Text Available The operation of wireless personal communication terminals very close to the user inherently faces the problem of electromagnetic (EM coupling between the device and the biological tissues. In this paper the effects of the electromagnetic antenna-human interaction is studied for a laptop MIMO antenna system, where four integrated antenna elements can operate simultaneously. Two points of view are considered: antenna performance and EM dosimetry. The first one addresses not only the degradation of the antenna performance but includes also the effect of the human proximity on the antenna characteristics, namely scattering matrix, Total Active Reflection Coefficient (TARC, radiation efficiency and envelope correlation between port signals. The exposure of the human tissues to EM radiation is expressed in terms of Specific Absorption Rate (SAR. These characteristics are evaluated as a function of the array excitation scheme (including phased array approach and MIMO-like signaling and compared to simple scenarios where all the power is radiated only by one antenna element.
A Flexible Phased-MIMO Array Antenna with Transmit Beamforming
Directory of Open Access Journals (Sweden)
Wen-Qin Wang
2012-01-01
Full Text Available Although phased-array antennas have been widely employed in modern radars, the requirements of many emerging applications call for new more advanced array antennas. This paper proposes a flexible phased-array multiple-input multiple-output (MIMO array antenna with transmit beamforming. This approach divides the transmit antenna array into multiple subarrays that are allowed to overlap each subarray coherently transmits a distinct waveform, which is orthogonal to the waveforms transmitted by other subarrays, at a distinct transmit frequency. That is, a small frequency increment is employed in each subarray. Each subarray forms a directional beam and all beams may be steered to different directions. The subarrays jointly offer flexible operating modes such as MIMO array which offers spatial diversity gain, phased-array which offers coherent directional gain and frequency diverse array which provides range-dependent beampattern. The system performance is examined by analyzing the transmit-receive beampatterns. The proposed approach is validated by extensive numerical simulation results.
Efficient coordinated recovery of sparse channels in massive MIMO
Masood, Mudassir
2015-01-01
This paper addresses the problem of estimating sparse channels in massive MIMO-OFDM systems. Most wireless channels are sparse in nature with large delay spread. In addition, these channels as observed by multiple antennas in a neighborhood have approximately common support. The sparsity and common support properties are attractive when it comes to the efficient estimation of large number of channels in massive MIMO systems. Moreover, to avoid pilot contamination and to achieve better spectral efficiency, it is important to use a small number of pilots. We present a novel channel estimation approach which utilizes the sparsity and common support properties to estimate sparse channels and requires a small number of pilots. Two algorithms based on this approach have been developed that perform Bayesian estimates of sparse channels even when the prior is non-Gaussian or unknown. Neighboring antennas share among each other their beliefs about the locations of active channel taps to perform estimation. The coordinated approach improves channel estimates and also reduces the required number of pilots. Further improvement is achieved by the data-aided version of the algorithm. Extensive simulation results are provided to demonstrate the performance of the proposed algorithms.
MIMO-OFDM signal optimization for SAR imaging radar
Baudais, J.-Y.; Méric, S.; Riché, V.; Pottier, É.
2016-12-01
This paper investigates the optimization of the coded orthogonal frequency division multiplexing (OFDM) transmitted signal in a synthetic aperture radar (SAR) context. We propose to design OFDM signals to achieve range ambiguity mitigation. Indeed, range ambiguities are well known to be a limitation for SAR systems which operates with pulsed transmitted signal. The ambiguous reflected signal corresponding to one pulse is then detected when the radar has already transmitted the next pulse. In this paper, we demonstrate that the range ambiguity mitigation is possible by using orthogonal transmitted wave as OFDM pulses. The coded OFDM signal is optimized through genetic optimization procedures based on radar image quality parameters. Moreover, we propose to design a multiple-input multiple-output (MIMO) configuration to enhance the noise robustness of a radar system and this configuration is mainly efficient in the case of using orthogonal waves as OFDM pulses. The results we obtain show that OFDM signals outperform conventional radar chirps for range ambiguity suppression and for robustness enhancement in 2 ×2 MIMO configuration.
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。
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.
Stiefel Manifold and TCQ based on Unit Memory Coding for MIMO System
Directory of Open Access Journals (Sweden)
Vijey Thayananthan
2014-02-01
Full Text Available The Multi Input and Multi Output (MIMO systems have been analyzed with a number of quantization techniques. In this short communication, few problems like performance and accuracy are investigated through a quantization technique based on Stiefel Manifold (SM. In order to improve these problems, suitable Trellis Coded Quantization (TCQ based on Unit Memory (UM coding is studied and applied to SM of MIMO components as a novel approach. Anticipated results are the bit error performance which is an overall improvement of feedback connected between transmitter and receiver of MIMO. As a conclusion, this research not only reduces the quantization problems on SM but also improve the performance and accuracy of limited-rate feedback used in MIMO system.
BROADCAST SCHEDULING WITH MIMO LINKS IN MULTI-HOP AD HOC NETWORKS
Institute of Scientific and Technical Information of China (English)
Zhang Guanghui; Li Jiandong; Zhao Min; Li Changle
2007-01-01
As the current medium access control protocols with Multiple Input Multiple Output (MIMO) links only bear point to point service, broadcast scheduling algorithm in ad hoc networks with MIMO links is proposed. The key to the proposed broadcast scheduling algorithm is the time slot scheduling algorithm which guarantees collision-free transmissions for every node and the minimum frame length. The proposed algorithm increases the simultaneous transmissions of MIMO links efficiently. Due to the interference null capacity of MIMO links, the interference node set of each node can decrease from two-hop neighbors to one-hop neighbors possibly. Simulation results show that our algorithm can greatly improve network capacity and decrease average packet delay.
Performance Improvement of BER in MIMO Systems with SVD-Based Precoding Approach
Directory of Open Access Journals (Sweden)
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.
Survey of Channel and Radio Propagation Models for Wireless MIMO Systems
Directory of Open Access Journals (Sweden)
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.
Directory of Open Access Journals (Sweden)
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.
Polyphase orthogonal waveform optimization for MIMO-SAR using Genetic Algorithm
Mehany, Wael; Jiao, Licheng; Hussien, Khaled
2014-04-01
A Multi-Input Multi-Output (MIMO) radar can be used to form a synthetic aperture for high resolution imaging. To successfully utilize the MIMO Synthetic Aperture Radar (SAR) system for practical imaging application, the orthogonal waveform design plays a critical role in image formation. Focusing on the SAR application, a definition for synthetic Integrated Side-Lobe level Ratio (ISLR) is proposed. In this paper a cost function containing ISLR and Peak Side-Lobe level Ratio (PSLR) is presented. A Genetic Algorithm (GA) is presented to numerically optimize orthogonal polyphase code sets design. The obtained waveform can be implemented for MIMO-SAR systems to improve the resolution. The simulation results show that the superiority of the proposed algorithm over other algorithms for the design of polyphase code sets used in MIMO-SAR.
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...
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.
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
Directory of Open Access Journals (Sweden)
Tomohiro Ono
2005-08-01
Full Text Available In this paper, a generalized spectral subtraction approach for reducing additive impulsive noise, narrowband signals, white Gaussian noise and DS-CDMA interferences in MIMO channel DS-CDMA wireless communication systems is investigated. The interference noise reduction or suppression is essential problem in wireless mobile communication systems to improve the quality of communication. The spectrum subtraction scheme is applied to the interference noise reduction problems for noisy MIMO channel systems. The interferences in space and time domain signals can effectively be suppressed by selecting threshold values, and the computational load with the FFT is not large. Further, the fading effects of channel are compensated by spectral modification with the spectral subtraction process. In the simulations, the effectiveness of the proposed methods for the MIMO channel DS-CDMA is shown to compare with the conventional MIMO channel DS-CDMA.
The Performance Analysis of PAPR Reduction using a novel PTS technique in OFDM-MIMO System
Directory of Open Access Journals (Sweden)
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.
Survey of Channel and Radio Propagation Models for Wireless MIMO Systems
Directory of Open Access Journals (Sweden)
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.
Covert Communication in MIMO-OFDM System Using Pseudo Random Location of Fake Subcarriers
Directory of Open Access Journals (Sweden)
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.
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.
Clustering under Perturbation Resilience
Balcan, Maria Florina
2011-01-01
Recently, Bilu and Linial \\cite{BL} formalized an implicit assumption often made when choosing a clustering objective: that the optimum clustering to the objective should be preserved under small multiplicative perturbations to distances between points. They showed that for max-cut clustering it is possible to circumvent NP-hardness and obtain polynomial-time algorithms for instances resilient to large (factor $O(\\sqrt{n})$) perturbations, and subsequently Awasthi et al. \\cite{ABS10} considered center-based objectives, giving algorithms for instances resilient to O(1) factor perturbations. In this paper, we greatly advance this line of work. For the $k$-median objective, we present an algorithm that can optimally cluster instances resilient to $(1 + \\sqrt{2})$-factor perturbations, solving an open problem of Awasthi et al.\\cite{ABS10}. We additionally give algorithms for a more relaxed assumption in which we allow the optimal solution to change in a small $\\epsilon$ fraction of the points after perturbation. ...
A hybrid variational-perturbational nuclear motion algorithm
Fábri, Csaba; Furtenbacher, Tibor; Császár, Attila G.
2014-09-01
A hybrid variational-perturbational nuclear motion algorithm based on the perturbative treatment of the Coriolis coupling terms of the Eckart-Watson kinetic energy operator following a variational treatment of the rest of the operator is described. The algorithm has been implemented in the quantum chemical code DEWE. Performance of the hybrid treatment is assessed by comparing selected numerically exact variational vibration-only and rovibrational energy levels of the C2H4, C2D4, and CH4 molecules with their perturbatively corrected counterparts. For many of the rotational-vibrational states examined, numerical tests reveal excellent agreement between the variational and even the first-order perturbative energy levels, whilst the perturbative approach is able to reduce the computational cost of the matrix-vector product evaluations, needed by the iterative Lanczos eigensolver, by almost an order of magnitude.
Robust signal recovery algorithm for structured perturbation compressive sensing
Institute of Scientific and Technical Information of China (English)
Youhua Wang; Jianqiu Zhang
2016-01-01
It is understood that the sparse signal recovery with a standard compressive sensing (CS) strategy requires the measurement matrix known as a priori. The measurement matrix is, however, often perturbed in a practical application. In order to handle such a case, an optimization problem by exploiting the sparsity characteristics of both the perturbations and signals is formulated. An algorithm named as the sparse perturbation signal recovery algorithm (SPSRA) is then pro-posed to solve the formulated optimization problem. The analytical results show that our SPSRA can simultaneously recover the signal and perturbation vectors by an alternative iteration way, while the convergence of the SPSRA is also analyticaly given and guaranteed. Moreover, the support patterns of the sparse signal and structured perturbation shown are the same and can be exploited to improve the estimation accuracy and reduce the computation complexity of the algorithm. The numerical simulation results verify the effectiveness of analytical ones.
Finslerian perturbation for the $\\Lambda$CDM model
Li, Xin; Chang, Zhe
2013-01-01
We present Finslerian perturbation for the $\\Lambda$CDM model, which breaks the isotropic symmetry of the universe. The analysis on the Killing vectors shows that the Randers-Finsler spacetime breaks the isotropic symmetry even if the scalar perturbations of the FRW metric vanish. In Randers-Finsler spacetime, the modified geodesic equation deduces a modified Boltzmann equation. We propose a perturbational version of the gravitational field equation in Randers-Finsler spacetime, where we have omitted the curvature tensor that does not belong to the base space of the tangent bundle. The gravitational field equations for the gravitational wave are also presented. The primordial power spectrum of the gravitational wave is investigated. We show that the primordial power spectrum for super-horizon perturbations is unchanged. For sub-horizon perturbations, however, the power spectrum is modified.
Investigating the Impact of Hybrid/SPREAD MIMO-OFDM System for Spectral-Efficient Wireless Networks
Directory of Open Access Journals (Sweden)
Nirmalendu Bikas Sinha
2010-05-01
Full Text Available This research proposes a novel signal scheme called Hybrid spread MIMO-OFDM system which interface OFDM with CDMA and integrate this CDMA-OFDM to MIMO to generate a system functionally superior to MIMO-OFDM systems are considered as candidates for future broadband wireless service. OFDM may be combined with antenna arrays at the transmitter and receiver to increase the diversity gain and/or to enhance the system capacity on time-variant and frequency-selective channels, resulting in a Multiple-Input Multiple-Output (MIMO configuration. The multiplexing technique proposed here is the Code Division Multiple Accesses (CDMA scheme which is considered the solution for eliminating the distortion caused by fast fading and provides the inherent advantage of DS-CDMA systems incorporating a spreading signal based on PN code sequence, by providing user discrimination based on coding at the same carrier frequency and simultaneously. The OFDM component provides resistance to multipath effects making it unnecessary to use RAKE receivers for CDMA and thus avoid hardware complexity. In order to compare their performances, the effects of multipath signal propagation on the capacity, under both single and multi user channel, are examined. The Inter Symbol Interference (ISI is used as a suitable measure of multipath effect. The obtained results show that the multipath has more influence on the capacity of MIMO than MIMO-OFDM and spread MIMO-OFDM. In addition, spread MIMO-OFDM offers more average capacity than MIMO under both single and multi user channel. In comparison with MIMO-OFDM, the capacity of spread MIMO-OFDM is higher under the condition of the multi user channel scenario. MIMO-OFDM spread system is being implemented using AWG and VSA. Thus making it possible to implement 4G using hardware and MATLAB/SIMULINK.
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...
Capacity Limits and Multiplexing Gains of MIMO Channels with Transceiver Impairments
Björnson, Emil; Zetterberg, Per; Bengtsson, Mats; Ottersten, Björn
2013-01-01
International audience; The capacity of ideal MIMO channels has a high-SNR slope that equals the minimum of the number of transmit and receive antennas. This letter analyzes if this result holds when there are distortions from physical transceiver impairments. We prove analytically that such physical MIMO channels have a finite upper capacity limit, for any channel distribution and SNR. The high-SNR slope thus collapses to zero. This appears discouraging, but we prove the encouraging result t...
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.
Joint DOD/DOA Estimation in MIMO Radar Exploiting Time-Frequency Signal Representations
2012-05-08
direction-of-departure (DOD) and direction-of- arrival (DOA) information of maneuvering targets in a bistatic multiple-input multiple-output (MIMO) radar...CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report ( SAR ) 18. NUMBER OF PAGES 21 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b...departure (DOD) and direction-of- arrival (DOA) information of maneuvering targets in a bistatic multiple-input multiple-output (MIMO) radar system
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...
Institute of Scientific and Technical Information of China (English)
王洪
2013-01-01
采用MIMO技术的OFDM系统是现代移动通信的核心技术。本文首先介绍正交频分复用（OFDM）技术和多输入多输出（MIMO）系统的基本原理，简述MIMO- OFDM技术及其特点，并初步探讨MIMO- OFDM系统的关键技术。
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
MIMO-OFDM技术介绍：正交频分复用（OFDM）是在无线高速数据传输中常用的一种技术。OFDM可以利用设备的多天线结构在一个时变的多径衰落信道中提高分集增益和系统容量，这促成了MIMO-OFDM系统的出现。
Renormalized Cosmological Perturbation Theory
Crocce, M
2006-01-01
We develop a new formalism to study nonlinear evolution in the growth of large-scale structure, by following the dynamics of gravitational clustering as it builds up in time. This approach is conveniently represented by Feynman diagrams constructed in terms of three objects: the initial conditions (e.g. perturbation spectrum), the vertex (describing non-linearities) and the propagator (describing linear evolution). We show that loop corrections to the linear power spectrum organize themselves into two classes of diagrams: one corresponding to mode-coupling effects, the other to a renormalization of the propagator. Resummation of the latter gives rise to a quantity that measures the memory of perturbations to initial conditions as a function of scale. As a result of this, we show that a well-defined (renormalized) perturbation theory follows, in the sense that each term in the remaining mode-coupling series dominates at some characteristic scale and is subdominant otherwise. This is unlike standard perturbatio...
MIMO-OFDM信道估计新方法%New Method for MIMO-OFDM Channel Estimation
Institute of Scientific and Technical Information of China (English)
李世杰; 刘毓
2011-01-01
A new method to estimate the channel of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system with wavelet denoising is proposed based on wavelet transform to improve the performance of cannel estimation The channel estimation is performed by least square method, and then the estimated result is processed with wavelet denoising.The method need not know any statistical characteristic of channel in advance.The performance of the estimation is improved more obviously, compared with linear interpolation or DFT interpolation.The conclusion is proved by computer simulation.%利用小波变换思想,提出一种基于小波去噪的多输入多输出正交频分复用(MIMO-OFDM)系统信道估计方法,以提高信道估计性能.该方法首先利用最小二乘(LS)方法进行信道估计,然后对估计后的结果进行小波去噪处理.该方法不需要预先知道信道的统计特性,与传统最小二乘信道估计方法相比,性能有明显提高.
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.
DEFF Research Database (Denmark)
Yamamoto, Atsushi; Hayashi, Toshiteru; Ogawa, Koichi;
2007-01-01
Outdoor radio propagation experiments are presented at 2.4 GHz, using a handset MIMO antenna with two monopoles and two planar inverted-F antennas (PIFAs), adjacent to a human phantom in browsing stance. The propagation test was performed in an urban area of a city, which resulted in non lineof......-sight (NLOS) situations. In our investigation, the 4-by-4 MIMO and SISO channel capacities for the reception signals were evaluated. These measurements show that the handset MIMO antenna, close to the human operator, is capable of MIMO reception....
Achieving "Massive MIMO" Spectral Efficiency with a Not-so-Large Number of Antennas
Huh, Hoon; Papadopoulos, Haralabos C; Ramprashad, Sean A
2011-01-01
The main focus and contribution of this paper is a novel network-MIMO TDD architecture that achieves spectral efficiencies comparable with "Massive MIMO", with one order of magnitude fewer antennas per active user per cell. The proposed architecture is based on a family of network-MIMO schemes defined by small clusters of cooperating base stations, zero-forcing multiuser MIMO precoding with suitable inter-cluster interference constraints, uplink pilot signals reuse across cells, and frequency reuse. The key idea consists of partitioning the users population into geographically determined "bins", such that all users in the same bin are statistically equivalent, and use the optimal network-MIMO architecture in the family for each bin. A scheduler takes care of serving the different bins on the time-frequency slots, in order to maximize a desired network utility function that captures some desired notion of fairness. This results in a mixed-mode network-MIMO architecture, where different schemes, each of which i...
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.
Directory of Open Access Journals (Sweden)
R. Q. Shaddad
2014-01-01
Full Text Available The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO signals feeding multiple antennas in the fiber wireless (FiWi system. A novel optical frequency upconversion (OFU technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF. The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM. The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.
Performance Analysis of Cooperative Virtual MIMO Systems for Wireless Sensor Networks
Directory of Open Access Journals (Sweden)
Adnan Al-Anbuky
2013-05-01
Full Text Available Multi-Input Multi-Output (MIMO techniques can be used to increase the data rate for a given bit error rate (BER and transmission power. Due to the small form factor, energy and processing constraints of wireless sensor nodes, a cooperative Virtual MIMO as opposed to True MIMO system architecture is considered more feasible for wireless sensor network (WSN applications. Virtual MIMO with Vertical-Bell Labs Layered Space-Time (V-BLAST multiplexing architecture has been recently established to enhance WSN performance. In this paper, we further investigate the impact of different modulation techniques, and analyze for the first time, the performance of a cooperative Virtual MIMO system based on V-BLAST architecture with multi-carrier modulation techniques. Through analytical models and simulations using real hardware and environment settings, both communication and processing energy consumptions, BER, spectral efficiency, and total time delay of multiple cooperative nodes each with single antenna are evaluated. The results show that cooperative Virtual-MIMO with Binary Phase Shift Keying-Wavelet based Orthogonal Frequency Division Multiplexing (BPSK-WOFDM modulation is a promising solution for future high data-rate and energy-efficient WSNs.
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
Color-Space-Based Visual-MIMO for V2X Communication.
Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo
2016-04-23
In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance.
Shaddad, R Q; Mohammad, A B; Al-Gailani, S A; Al-Hetar, A M
2014-01-01
The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.
An Estimation Method for MIMO Radar Gain and Phase Errors%一种MIMO雷达幅相误差估计方法
Institute of Scientific and Technical Information of China (English)
徐青; 廖桂生; 张娟; 曾操
2012-01-01
针对单基地相关多输入多输出(MIMO)雷达中存在的阵列幅相误差问题进行了研究.给出了单基地相关MIMO雷达的阵列模型,并提出了一种MIMO雷达幅相误差估计方法.利用发射正交信号对阵列接收信号进行匹配滤波,可分离得到类似传统阵列的“虚拟阵列”,利用分时信源数据将该阵列中真实导向矢量中信源波达方向(DOA)引起的相位与幅相误差分离开,通过构造代价函数得到波达方向估计值,进而分别得到发射阵与接收阵的幅相误差的估计值,同时给出了误差引入量分析.最后通过仿真验证了该方法的有效性.本文介绍的方法简单可行,适用于任意构型MIMO雷达的幅相误差估计.%This paper studies the problem of estimation of array gain and phase errors in a collocated multiple-input multiple-output (MIMO) radar. An array model for a monostatic collocated MIMO radar is presented, and a method that estimates the gain and phase errors for MIMO radar systems is also given. By using the transmitted orthogonal waveforms to match the received signals, a "virtual array" similar to the conventional array can be obtained. Based on the time-sharing data, the phase caused by the direction of arrival (DOA) of the time-sharing signal and the gain and phase errors are separated from each other in the "virtual array" real steering vector. A cost function is structured to get the DOA estimation, and then the gain and phase errors are estimated based on the DOA estimates obtained afore. The remainder error induced by the estimation process is analyzed. Finally, the validity of the model is testified through computer simulation. The method introduced in this paper is simple and feasible, and suitable for any array manifold.
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.
Revisiting perturbations in extended quasidilaton massive gravity
Heisenberg, Lavinia
2015-04-01
In this work we study the theory of extended quasidilaton massive gravity together with the presence of matter fields. After discussing the homogeneous and isotropic fully dynamical background equations, which governs the exact expansion history of the universe, we consider small cosmological perturbations around these general FLRW solutions. The stability of tensor, vector and scalar perturbations on top of these general background solutions give rise to slightly different constraints on the parameters of the theory than those obtained in the approximative assumption of the late-time asymptotic form of the expansion history, which does not correspond to our current epoch. This opens up the possibility of stable FLRW solutions to be compared with current data on cosmic expansion with the restricted parameter space based on theoretical ground.
Revisiting perturbations in extended quasidilaton massive gravity
Heisenberg, Lavinia
2015-01-01
In this work we study the theory of extended quasidilaton massive gravity together with the presence of matter fields. After discussing the homogeneous and isotropic fully dynamical background equations, which governs the exact expansion history of the universe, we consider small cosmological perturbations around these general FLRW solutions. The stability of tensor, vector and scalar perturbations on top of these general background solutions give rise to slightly different constraints on the parameters of the theory than those obtained in the approximative assumption of the late-time asymptotic form of the expansion history, which does not correspond to our current epoch. This opens up the possibility of stable FLRW solutions to be compared with current data on cosmic expansion with the restricted parameter space based on theoretical ground.
Non-perturbative QCD Modeling and Meson Physics
Nguyen, T; Tandy, P C
2009-01-01
Using a ladder-rainbow kernel previously established for light quark hadron physics, we explore the extension to masses and electroweak decay constants of ground state pseudoscalar and vector quarkonia and heavy-light mesons in the c- and b-quark regions. We make a systematic study of the effectiveness of a constituent mass concept as a replacement for a heavy quark dressed propagator for such states. The difference between vector and axial vector current correlators is explored within the same model to provide an estimate of the four quark chiral condensate and the leading distance scale for the onset of non-perturbative phenomena in QCD.
DEFF Research Database (Denmark)
jora, Renata; Schechter, Joseph; Naeem Shahid, M.
2009-01-01
We study the effects of the perturbation which violates the permutation symmetry of three Majorana neutrinos but preserves the well known (23) interchange symmetry. This is done in the presenceof an arbitrary Majorana phase which serves to insure the degeneracy of the three neutrinos at the unper...
Instantaneous stochastic perturbation theory
Lüscher, Martin
2015-01-01
A form of stochastic perturbation theory is described, where the representative stochastic fields are generated instantaneously rather than through a Markov process. The correctness of the procedure is established to all orders of the expansion and for a wide class of field theories that includes all common formulations of lattice QCD.
DEFF Research Database (Denmark)
2012-01-01
The present invention relates to a compact, reliable and low-cost vector velocimeter for example for determining velocities of particles suspended in a gas or fluid flow, or for determining velocity, displacement, rotation, or vibration of a solid surface, the vector velocimeter comprising a laser...... assembly for emission of a measurement beam for illumination of an object in a measurement volume with coherent light whereby a signal beam emanating from the object in the measurement volume is formed in response to illumination of the object by the measurement beam, a reference beam generator...... detector element signal when the fringe pattern formed by the interfering signal beam and reference beam moves across the first detector array; and a signal processor that is adapted for generation of a velocity signal corresponding to a first velocity component of movement of the object in the measurement...
DEFF Research Database (Denmark)
2012-01-01
for generation of a reference beam, a detector system comprising a first detector arrangement arranged in such a way that the signal beam and the reference beam are incident upon the first detector arrangement with the reference beam propagating at an angle relative to a signal beam, and wherein the first......The present invention relates to a compact, reliable and low-cost vector velocimeter for example for determining velocities of particles suspended in a gas or fluid flow, or for determining velocity, displacement, rotation, or vibration of a solid surface, the vector velocimeter comprising a laser...... assembly for emission of a measurement beam for illumination of an object in a measurement volume with coherent light whereby a signal beam emanating from the object in the measurement volume is formed in response to illumination of the object by the measurement beam, a reference beam generator...
Klingelhoefer, G.; Morris, R. V.; Blumers, M.; Bernhardt, B.; Graff, T.
2011-01-01
For the advanced Moessbauer instrument MIMOS IIA, the new detector technologies and electronic components increase sensitivity and performance significantly. In combination with the high energy resolution of the SDD it is possible to perform X-ray fluorescence analysis simultaneously to Moessbauer spectroscopy. In addition to the Fe-mineralogy, information on the sample's elemental composition will be gathered. The ISRU 2010 field campaign demonstrated that in-situ Moessbauer spectroscopy is an effective tool for both science and feedstock exploration and process monitoring. Engineering tests showed that a compact nickel metal hydride battery provided sufficient power for over 12 hr of continuous operation for the MIMOS instruments.
An Imaging Method of MIMO-SAR with Compressed Echo Data%基于回波数据压缩的MIMO-SAR成像方法
Institute of Scientific and Technical Information of China (English)
谢矿生
2015-01-01
The amount of echo data is huge in multiple input multiple output synthetic aperture radar( MI-MO-SAR) imaging with high resolution. To solve this problem,an imaging method of MIMO-SAR based on compressed echo data is proposed. Firstly,the echo signal model of MIMO-SAR system is analyzed and the phase error induced by MIMO radar is compensated. Secondly,the echo signal is preprocessed by the Range Migration Algorithm( RMA) ,and also the sparsity of the processed data is analyzed. Then the pre-processed data is compressed and transmitted. In the ground receiver,the sparse expression of echo data in Range-Doppler( RD) domain is reconstructed. Finally,the simulation result shows that the amount of the transmitted data by the proposed method is less than that by the conventional MIMO-SAR imaging method.%针对多发多收合成孔径雷达( MIMO-SAR)高分辨成像的回波数据量过大问题，提出了一种基于数据压缩的MIMO-SAR成像方法。通过对MIMO-SAR回波数据的分析，补偿了由于MIMO雷达收发分置导致的相位误差；其次利用距离徙动算法( RMA)对回波数据进行预处理并分析了其稀疏性；然后针对预处理后的回波数据进行压缩传输，在接收端利用压缩感知重构算法获得回波数据在距离多普勒域的稀疏表示并进行成像处理。仿真结果表明，所提方法可以在大幅压缩MIMO-SAR回波数据的基础上实现准确成像。
Perturbation Theory of Massive Yang-Mills Fields
Veltman, M.
1968-08-01
Perturbation theory of massive Yang-Mills fields is investigated with the help of the Bell-Treiman transformation. Diagrams containing one closed loop are shown to be convergent if there are more than four external vector boson lines. The investigation presented does not exclude the possibility that the theory is renormalizable.
Perturbation theory of massive Yang-Mills fields
Veltman, M.J.G.
1968-01-01
Perturbation theory of massive Yang-Mills fields is investigated with the help of the Bell-Treiman transformation. Primitive diagrams containing one closed loop are shown to be convergent if there are more than four external vector boson lines. The investigation presented does not exclude the possib
High order multiplication perturbation method for singular perturbation problems
Institute of Scientific and Technical Information of China (English)
张文志; 黄培彦
2013-01-01
This paper presents a high order multiplication perturbation method for sin-gularly perturbed two-point boundary value problems with the boundary layer at one end. By the theory of singular perturbations, the singularly perturbed two-point boundary value problems are first transformed into the singularly perturbed initial value problems. With the variable coeﬃcient dimensional expanding, the non-homogeneous ordinary dif-ferential equations (ODEs) are transformed into the homogeneous ODEs, which are then solved by the high order multiplication perturbation method. Some linear and nonlinear numerical examples show that the proposed method has high precision.