Topic
Multi-user MIMO
About: Multi-user MIMO is a research topic. Over the lifetime, 10265 publications have been published within this topic receiving 227206 citations. The topic is also known as: multi user mimo & MU-MIMO.
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Papers
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11 Dec 2012TL;DR: This work considers the uplink of multicell multiuser MIMO (MU-MIMO) systems with very large antenna arrays at the base station and proposes an optimal linear receiver (OLR) which maximizes the received signal-to-interference-plus-noise (SINR).
Abstract: We consider the uplink of multicell multiuser MIMO (MU-MIMO) systems with very large antenna arrays at the base station (BS). We assume that the BS estimates the channel through uplink training, and then uses this channel estimate to detect the signals transmitted from a multiplicity of autonomous users in its cell. By taking the correlation between the channel estimate and the interference from other cells into account, we propose an optimal linear receiver (OLR) which maximizes the received signal-to-interference-plus-noise (SINR). Analytical approximations of the exact and lower bound on the achievable rate are then derived. The bound is very tight, especially at large number of BS antennas. We show that at low SINR, maximalratio combing (MRC) receiver performs as well as OLR, however at high SINR, OLR outperforms MRC. Compared with the typical minimum mean-square error receiver, our proposed OLR improves systematically the system performance, especially when the interference is large.
49 citations
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07 Sep 2003TL;DR: It is shown that the implementation complexity can be reduced further to meet the requirements for future high speed downlink packet access (HSDPA) systems with MIMO extensions in 3/sup rd/ generation (3G) mobile wireless systems.
Abstract: This paper describes a VLSI implementation of V-BLAST detection for future multiple-input-multiple-output (MIMO) wireless communications. This design is implemented using a 0.35-/spl mu/m 5-layer metal 3.3 V CMOS technology. For a 4-transmit and 4-receive antennas system using QPSK modulation scheme, a detecting throughput of 128 Mb/s can be achieved. Furthermore, it is shown that the implementation complexity can be reduced further to meet the requirements for future high speed downlink packet access (HSDPA) systems with MIMO extensions in 3/sup rd/ generation (3G) mobile wireless systems.
49 citations
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07 May 2008TL;DR: The performance of MU-MIMO operation in 3GPP LTE for different frequency granularities of the precoder at the OFDM transmitter is investigated and the impact of channel correlation on the performance of the receiver when it is unaware of the interfererpsilas precoding vector is investigated.
Abstract: For scenarios with a large number of users to be served in one cell, high capacity gains can be achieved by transmitting independent data streams to different users sharing the same time-frequency resources. This technique is known as Multi-User MIMO (MU-MIMO). In this paper we investigate the performance of MU-MIMO operation in 3GPP LTE for different frequency granularities of the precoder at the OFDM transmitter. We also investigate the impact of channel correlation on the performance of the receiver when it is unaware of the interfererpsilas precoding vector. The performance is evaluated by means of semistatic system simulations.
49 citations
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TL;DR: The prediction technique was shown to track the channel and improve the BER performance almost to that in the ideal time invariant case, and the bit-error rate (BER) performance was obtained.
Abstract: In this paper, the performance of a multi-user multiple-input multiple-output (MIMO) system in time-varying channels is evaluated using measurement data. We consider the multi-user MIMO system using a block diagonalization (BD) scheme and an eigenbeam-space division multiplexing (E-SDM) technique. In an ideal case, the BD scheme eliminates inter-user interference, and the E-SDM technique suppresses inter-stream interference. In actual radio environments, however, channels change over time. This causes interference in the multi-user MIMO system even though the BD scheme and the E-SDM technique are used. To overcome this problem, the authors have developed a simple channel prediction scheme on the basis of a linear extrapolation and have demonstrated its effectiveness by computer simulations assuming the Jakes' model. To verify the performance of the channel prediction scheme in actual environments, we conducted a measurement campaign in indoor environments and measured a large amount of channel data. Using these data, we examined the channel transition and channel tracking with the prediction method. Then we obtained the bit-error rate (BER) performance. The prediction technique was shown to track the channel and improve the BER performance almost to that in the ideal time invariant case.
49 citations
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TL;DR: This paper considers two different cognitive WPCN protocols depending on the cooperation level between the primary transmitter and the secondary H-AP, and forms sum throughput maximization problems by taking the interference leakage to the primary network into consideration.
Abstract: In this paper, we study multi-user multi-input multi-output cognitive wireless powered communication networks (WPCN), in which a secondary WPCN shares spectrum with a primary wireless information transfer system. A typical WPCN consists of two different phases. In the first downlink phase, a hybrid access point (H-AP) transfers energy to charge users, and then in the subsequent uplink phase, the users send information by using the harvested energy to the H-AP. We consider two different cognitive WPCN protocols depending on the cooperation level between the primary transmitter and the secondary H-AP. For both cases, we formulate sum throughput maximization problems by taking the interference leakage to the primary network into consideration. The problems are generally non-convex due to coupled variables in the WPCN. To tackle this issue, we first convert the problems into equivalent convex forms, and then identify the global optimal solutions by applying the proposed iterative optimization algorithms. Finally, the simulation results demonstrate that the proposed algorithms outperform conventional schemes.
49 citations