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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.


Papers
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01 Jan 2004
TL;DR: The results show the applicability of MIMO techniques in such sensor networks with judicious system design, as well as the dependence of energy efficiency on coherence time of the fading process and communications distance.
Abstract: Energy efficiency of MIMO techniques in wireless sensor networks is analyzed. Assuming a cooperative sensor network, the energy consumption of MIMO-based wireless sensor networks is compared with conventional SISO sensor networks. The dependence of energy efficiency on coherence time of the fading process and communications distance is considered. Our results show the applicability of MIMO techniques in such sensor networks with judicious system design.

126 citations

Proceedings ArticleDOI
01 Dec 2013
TL;DR: A hybrid beamforming architecture that combines an analog beamforming with array antennas and a digital precoding with multiple RF chains is proposed and a multi-beam transmission diversity scheme for single stream transmission for single user MIMO operation is proposed.
Abstract: The ever-increasing traffic crunch for the wireless communication has drawn attention to the large spectrum available in the millimeter-wave bands as a potential means to achieve several fold mobile data traffic increase. While the channel characteristics at the millimeter-wave bands are known to be unfavorable for the mobile wireless communication purpose, the high gain available from massive array antenna facilitated by the short wavelength makes it possible to overcome the large path-loss. In this paper, we propose a hybrid beamforming architecture that combines an analog beamforming with array antennas and a digital precoding with multiple RF chains. Furthermore, we propose a multi-beam transmission diversity scheme for single stream transmission for single user MIMO operation. It is shown through various simulation results that the proposed hybrid beamforming scheme leads to considerable performance improvements even with limited feedback.

125 citations

Journal ArticleDOI
TL;DR: Minimum dc bias, unified dc bias and asymmetrically clipped optical OFDM-based schemes are proposed to generate real-valued nonnegative signals for intensity modulation, and their performances are validated via simulations with zero forcing and minimum mean-squared error (MMSE) precoding techniques.
Abstract: Visible light communication (VLC) is emerging as a promising technique to provide ubiquitous wireless connection. In this paper, a multiuser VLC system utilizing multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) is investigated. Since the distances of the multiple transmitter–receiver links are different, their temporal delays are also different, resulting in complex channel gain and phase differences when transformed to the frequency domain. For each subcarrier in OFDM, the corresponding precoding matrix is calculated in the frequency domain to eliminate multiuser interference. Phase information in the frequency domain is first considered, where complex, instead of real, channel matrices are used for precoding, which reduces the channel correlation and achieves better performance. Moreover, minimum dc bias, unified dc bias, and asymmetrically clipped optical OFDM-based schemes are proposed to generate real-valued nonnegative signals for intensity modulation, and their performances are validated via simulations with zero forcing and minimum mean-squared error (MMSE) precoding techniques.

125 citations

Journal ArticleDOI
TL;DR: The maximum spectral efficiency of MIMO systems in which both transmitter and receiver know the channel (using channel estimate feedback) is compared with MIMOs in which only the receiver knows the channel and capacity loss associated with channel estimation error at the transmitter is introduced.
Abstract: Wireless communication using multiple-input multiple-output (MIMO) systems enables increased spectral efficiency for a given total transmit power. Increased capacity is achieved by introducing additional spatial channels that are exploited using space-time coding. In this paper, the environmental factors that affect MIMO capacity are surveyed. These factors include channel complexity, external interference, and channel estimation error. The maximum spectral efficiency of MIMO systems in which both transmitter and receiver know the channel (using channel estimate feedback) is compared with MIMO systems in which only the receiver knows the channel. Channel complexity is studied using both simple stochastic physical scattering and asymptotic large random matrix models. Both uncooperative (worst-case) and cooperative (amenable to multiuser detection) interference are considered. An analysis for capacity loss associated with channel estimation error at the transmitter is introduced.

125 citations

Journal ArticleDOI
TL;DR: This work considers both the single-user and the multi-user power allocation problems in MIMO systems, where the receiver side has the perfect channel state information (CSI) and the transmitter side has partial CSI, which is in the form of covariance feedback.
Abstract: We consider both the single-user and the multi-user power allocation problems in MIMO systems, where the receiver side has the perfect channel state information (CSI), and the transmitter side has partial CSI, which is in the form of covariance feedback. In a single-user MIMO system, we consider an iterative algorithm that solves for the eigenvalues of the optimum transmit covariance matrix that maximizes the rate. The algorithm is based on enforcing the Karush-Kuhn-Tucker (KKT) optimality conditions of the optimization problem at each iteration. We prove that this algorithm converges to the unique global optimum power allocation when initiated at an arbitrary point. We, then, consider the multi-user generalization of the problem, which is to find the eigenvalues of the optimum transmit covariance matrices of all users that maximize the sum rate of the MIMO multiple access channel (MIMO-MAC). For this problem, we propose an algorithm that finds the unique optimum power allocation policies of all users. At a given iteration, the multi-user algorithm updates the power allocation of one user, given the power allocations of the rest of the users, and iterates over all users in a round-robin fashion. Finally, we make several suggestions that significantly improve the convergence rate of the proposed algorithms.

125 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202363
2022122
2021170
2020211
2019234
2018263