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Channel Estimation and Data Detection for MIMO Systems under Spatially and Temporally Colored Interference  [cached]
Song Yi,Blostein Steven D
EURASIP Journal on Advances in Signal Processing , 2004,
Abstract: The impact of interference on multiple-input multiple-output (MIMO) systems has recently attracted interest. Most studies of channel estimation and data detection for MIMO systems consider spatially and temporally white interference at the receiver. In this paper, we address channel estimation, interference correlation estimation, and data detection for MIMO systems under both spatially and temporally colored interference. We examine the case of one dominant interferer in which the data rate of the desired user could be the same as or a multiple of that of the interferer. Assuming known temporal interference correlation as a benchmark, we derive maximum likelihood (ML) estimates of the channel matrix and spatial interference correlation matrix, and apply these estimates to a generalized version of the Bell Labs Layered Space-Time (BLAST) ordered data detection algorithm. We then investigate the performance loss by not exploiting interference correlation. For a MIMO system undergoing independent Rayleigh fading, we observe that exploiting both spatial and temporal interference correlation in channel estimation and data detection results in potential gains of 1.5 dB and 4 dB for an interferer operating at the same data rate and at half the data rate, respectively. Ignoring temporal correlation, it is found that spatial correlation accounts for about 1 dB of this gain.
On the transmit strategy for the interference MIMO relay channel in the low power regime  [PDF]
Anas Chaaban,Aydin Sezgin
Mathematics , 2009,
Abstract: This paper studies the interference channel with two transmitters and two receivers in the presence of a MIMO relay in the low transmit power regime. A communication scheme combining block Markov encoding, beamforming, and Willems' backward decoding is used. With this scheme, we get an interference channel with channel gains dependent on the signal power. A power allocation for this scheme is proposed, and the achievable rate region with this power allocation is given. We show that, at low transmit powers, with equal power constraints at the relay and the transmitters, the interference channel with a MIMO relay achieves a sum rate that is linear in the power. This sum rate is determined by the channel setup. We also show that in the presence of abundant power at the relay, the transmit strategy is significantly simplified, and the MAC from the transmitters to the relay forms the bottle neck of the system from the sum rate point of view.
Approximate Analysis of Power Offset over Spatially Correlated MIMO Channels  [PDF]
Guangwei YU, Xuzhen WANG
Communications and Network (CN) , 2009, DOI: 10.4236/cn.2009.11004
Abstract: Power offset is zero-order term in the capacity versus signal-to-noise ratio curve. In this paper, approximate analysis of power offset is presented to describe MIMO system with uniform linear antenna arrays of fixed length. It is assumed that the number of receive antenna is larger than that of transmit antenna. Spatially Correlated MIMO Channel is approximated by tri-diagonal toeplitz matrix. The determinant of tri-diagonal toeplitz matrix, which is fitted by elementary curve, is one of the key factors related to power offset. Based on the curve fitting, the determinant of tri-diagonal toeplitz matrix is mathematically tractable. Consequently, the expression of local extreme points can be derived to optimize power offset. The simulation results show that approximation above is accurate in local extreme points of power offset. The proposed expression of local extreme points is helpful to approach optimal power offset.
MIMO Z Channel Interference Management  [PDF]
Ian Lim
Mathematics , 2012,
Abstract: MIMO Z Channel is investigated in this paper. We focus on how to tackle the interference when different users try to send their codewords to their corresponding receivers while only one user will cause interference to the other. We assume there are two transmitters and two receivers each with two antennas. We propose a strategy to remove the interference while allowing different users transmit at the same time. Our strategy is low-complexity while the performance is good. Mathematical analysis is provided and simulations are given based on our system.
MIMO Interference Alignment Over Correlated Channels with Imperfect CSI  [PDF]
Behrang Nosrat-Makouei,Jeffrey G. Andrews,Robert W. Heath Jr
Mathematics , 2010, DOI: 10.1109/TSP.2011.2124458
Abstract: Interference alignment (IA), given uncorrelated channel components and perfect channel state information, obtains the maximum degrees of freedom in an interference channel. Little is known, however, about how the sum rate of IA behaves at finite transmit power, with imperfect channel state information, or antenna correlation. This paper provides an approximate closed-form signal-to-interference-plus-noise-ratio (SINR) expression for IA over multiple-input-multiple-output (MIMO) channels with imperfect channel state information and transmit antenna correlation. Assuming linear processing at the transmitters and zero-forcing receivers, random matrix theory tools are utilized to derive an approximation for the post-processing SINR distribution of each stream for each user. Perfect channel knowledge and i.i.d. channel coefficients constitute special cases. This SINR distribution not only allows easy calculation of useful performance metrics like sum rate and symbol error rate, but also permits a realistic comparison of IA with other transmission techniques. More specifically, IA is compared with spatial multiplexing and beamforming and it is shown that IA may not be optimal for some performance criteria.
Ian Lim,Chedd Marley,Jorge Kitazuru
International Journal of Computer Networks & Communications , 2012,
Abstract: MIMO Z Channel is investigated in this paper. We focus on how to tackle the interference when differentusers try to send their codewords to their corresponding receivers while only one user will causeinterference to the other. We assume there are two transmitters and two receivers each with two antennas.We propose a strategy to remove the interference while allowing different users transmit at the same time.Our strategy is low-complexity while the performance is good. Mathematical analysis is provided andsimulations are given based on our system.
Tucker Decomposition For Rotated Codebook in 3D MIMO System Under Spatially Correlated Channel  [PDF]
Fang Yuan
Mathematics , 2015,
Abstract: This correspondence proposes a new rotated codebook for three-dimensional (3D) multi-input-multi-output (MIMO) system under spatially correlated channel. To avoid the problem of high dimensionality led by large antenna array, the rotation matrix in the rotated codebook is proposed to be decomposed by Tucker decomposition into three lowdimensional units, i.e., statistical channel direction information in horizontal and vertical directions respectively, and statistical channel power in the joint horizontal and vertical direction. A closed-form suboptimal solution is provided to reduce the computational complexity in Tucker decomposition. The proposed codebook has a significant dimension reduction from conventional rotated codebooks, and is applicable for 3D MIMO system with arbitrary form of antenna array. Simulation results demonstrate that the proposed codebook works very well for various 3D MIMO systems.
Pilot Reuse for Massive MIMO Transmission over Spatially Correlated Rayleigh Fading Channels  [PDF]
Li You,Xiqi Gao,Xiang-Gen Xia,Ni Ma,Yan Peng
Mathematics , 2015, DOI: 10.1109/TWC.2015.2404839
Abstract: We propose pilot reuse (PR) in single cell for massive multiuser multiple-input multiple-output (MIMO) transmission to reduce the pilot overhead. For spatially correlated Rayleigh fading channels, we establish a relationship between channel spatial correlations and channel power angle spectrum when the base station antenna number tends to infinity. With this channel model, we show that sum mean square error (MSE) of channel estimation can be minimized provided that channel angle of arrival intervals of the user terminals reusing the pilots are non-overlapping, which shows feasibility of PR over spatially correlated massive MIMO channels with constrained channel angular spreads. Regarding that channel estimation performance might degrade due to PR, we also develop the closed-form robust multiuser uplink receiver and downlink precoder that minimize sum MSE of signal detection, and reveal a duality between them. Subsequently, we investigate pilot scheduling, which determines the PR pattern, under two minimum MSE related criteria, and propose a low complexity pilot scheduling algorithm which relies on the channel statistics only. Simulation results show that the proposed PR scheme provides significant performance gains over the conventional orthogonal training scheme in terms of net spectral efficiency.
Exploiting Spatial and Frequency Diversity in Spatially Correlated MU-MIMO Downlink Channels  [PDF]
Rosdiadee Nordin
Journal of Computer Networks and Communications , 2012, DOI: 10.1155/2012/414796
Abstract: The effect of self-interference due to the increase of spatial correlation in a MIMO channel has become one of the limiting factors towards the implementation of future network downlink transmissions. This paper aims to reduce the effect of self-interference in a downlink multiuser- (MU-) MIMO transmission by exploiting the available spatial and frequency diversity. The subcarrier allocation scheme can exploit the frequency diversity to determine the self-interference from the ESINR metric, while the spatial diversity can be exploited by introducing the partial feedback scheme, which offers knowledge of the channel condition to the base station and further reduces the effect before the allocation process takes place. The results have shown that the proposed downlink transmission scheme offers robust bit error rate (BER) performance, even when simulated in a fully correlated channel, without imposing higher feedback requirements on the base controller. 1. Introduction Dynamic resource assignment from the Orthogonal Frequency Division Multiple Access (OFDMA) in combination with multiplicative increase in throughput from Multiple-Input Multiple-Output (MIMO) technology offers improved spectral diversity in a wireless downlink transmission. The result of this combination is able to provide a highly efficient and low latency with enhanced spectrum flexibility radio interface, as can be seen from the downlink implementation of a Long Term Evolution (LTE) network [1]. In addition, the LTE network benefits from MU-MIMO, a multiuser diversity technique that exploits the spatial diversity from the channel knowledge at the transmitter, that is, channel state information (CSI), to improve the performance gain. However, accurate CSI is obtained at the expense of massive feedback overhead. A partial feedback scheme, which is based on a quantized discrete Fourier transform (DFT), is considered in this paper. Instead of feeding back the full CSI, mobile users update the E-UTRAN Node B (eNodeB) with the preferred precoding matrix based on the channel quality indicator (CQI). The implementation of the full feedback scheme comes at the expense of CSI; therefore, it requires an enormous amount of feedback to the eNodeB. This scenario is not practical for the downlink implementation because eNodeB requires a higher level of computational overhead to compute the channel matrix. This situation worsens when the channel is severely impaired by channel imperfection, such as spatial correlation, which is also described by Gesbert et al. [2] as an effect of self-interference. This
Joint Channel Direction Information Quantization For Spatially Correlated 3D MIMO Channels  [PDF]
Fang Yuan,Chenyang Yang,Yang Song,Lan Chen,Yuichi Kakishima,Huiling Jiang
Mathematics , 2015,
Abstract: This paper proposes a codebook for jointly quantizing channel direction information (CDI) of spatially correlated three-dimensional (3D) multi-input-multi-output (MIMO) channels. To reduce the dimension for quantizing the CDI of large antenna arrays, we introduce a special structure to the codewords by using Tucker decomposition to exploit the unique features of 3D MIMO channels. Specifically, the codeword consists of four parts each with low dimension individually targeting at a different type of information: statistical CDIs in horizontal direction and in vertical direction, statistical power coupling, and instantaneous CDI. The proposed codebook avoids the redundancy led by existing independent CDI quantization. Analytical results provide a sufficient condition on 3D MIMO channels to show that the proposed codebook can achieve the same quantization performance as the well-known rotated codebook applied to the global channel CDI, but with significant reduction in the required statistical channel information. Simulation results validate our analysis and demonstrate that the proposed joint CDI quantization provides substantial performance gain over independent CDI quantization.
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