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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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Proceedings ArticleDOI
19 May 2008
TL;DR: In this paper, the problem of scheduling and preconditioning in the presence of reciprocal time-division duplex (TDD) training is considered, and a scheduling scheme is proposed and an improved lower bound on the sum capacity is derived.
Abstract: The downlink transmission in multi-user multiple- input multiple-output (MIMO) systems has been extensively studied from both communication-theoretic and information-theoretic perspectives. Most of these papers assume perfect/imperfect channel knowledge. In general, the problem of channel estimation is studied separately. However, in interference-limited communication systems with high mobility, the problem of channel estimation is tightly coupled with the problem of maximizing throughput of the system. In this paper, scheduling and preconditioning in the presence of reciprocal time-division duplex (TDD) training are considered. In the case of homogeneous users, a scheduling scheme is proposed and an improved lower bound on the sum capacity is derived. The problem of choosing training sequence length to maximize net throughput of the system is also studied. In the case of heterogeneous users, a modified pre-conditioning method is proposed and an optimized pre-conditioning matrix is derived. This method is combined with a scheduling scheme to further improve achievable weighted-sum rate.

42 citations

Journal ArticleDOI
TL;DR: This work presents novel design considerations and a compact antenna solution that could be reconfigured by dynamic adjustment of terminating loads to preserve its beam-space multiplexing capabilities over a 1:2 tuning range, thereby promoting the convergence of MIMO and dynamic spectrum allocation via reduced-complexity hardware.
Abstract: Recently, a technique called beam-space MIMO has been demonstrated as an effective approach for transmitting multiple signals while using a single RF-chain. In this work, we present novel design considerations and a compact antenna solution to stimulate the deployment of beam-space MIMO in future wireless applications. Targeting integration in small wireless devices, the novel antenna is made of a single integrated radiator rather than an array of physically-separated dipoles. It also drastically simplifies the implementation of variable loads and DC bias circuits for BPSK modulated signals, and does not require any external reconfigurable matching circuit. Finally, we show that this antenna system could be reconfigured by dynamic adjustment of terminating loads to preserve its beam-space multiplexing capabilities over a 1:2 tuning range, thereby promoting the convergence of MIMO and dynamic spectrum allocation via reduced-complexity hardware. A prototype achieving single-RF-chain multiplexing at a fixed frequency is designed and measured, showing excellent agreement between simulations and measurements.

42 citations

Proceedings ArticleDOI
25 Oct 2012
TL;DR: The scheme illustrates the joint utilization of current and past knowledge of the channel state information at the transmitter, and the degrees of freedom (DoF) region of the two-user - MIMO broadcast channel under this model is completely characterized.
Abstract: The two user multiple-input multiple-output (MIMO) broadcast channel is studied in which the channel from one of the receivers is known instantaneously and perfectly at the transmitter, whereas the channel from the other receiver is known in a delayed manner. The degrees of freedom (DoF) region of the two-user (M; N 1 ; N 2 ) - MIMO broadcast channel under this model is completely characterized. The scheme illustrates the joint utilization of current and past knowledge of the channel state information at the transmitter.

42 citations

Proceedings ArticleDOI
05 Sep 2008
TL;DR: In this article, the authors analytically derive a design prescript that allows for the construction of orthogonal channel matrices via the explicit positioning of two satellite antennas in the geostationary orbit.
Abstract: In line-of-sight (LOS) radio channels maximum multiple input multiple output (MIMO) channel capacity is obtained if an orthogonal MIMO channel transfer matrix is available. For the special case of the MIMO satellite channel, we will analytically derive a design prescript that allows for the construction of orthogonal channel matrices via the explicit positioning of two satellite antennas in the geostationary orbit. Simultaneously, a particular arrangement of an arbitrary number of ground station antennas placed on earth is assumed. In a computer simulation this conceptual design rule is illustrated and verified with a satellite communication link consisting of both a MIMO uplink channel and a MIMO downlink channel. The uplink is established between two anchor stations and a satellite system, also equipped with two antenna elements. In downlink direction the information is transferred from the two-antenna satellite system to a mobile receiver with an arbitrary number of antenna elements. The MIMO capacity optimization strategy is shown to exceed at least 90% of its theoretical maximum in all cases, nearly doubling the data rate compared to ordinary two- satellite MIMO systems, which are currently found in literature.

42 citations

Patent
15 Jul 2011
TL;DR: In this paper, an access point sets a first power level and a first modulation and coding scheme (MCS) for transmission of a first aggregated media access control (MAC) protocol data unit (A-MPDU) to the first station as a function of the first ISQ and an amount of payload data corresponding to the second MPDU.
Abstract: Embodiments of a system and method for transmitting data from an access point in a multiple user multiple input multiple output (MU-MIMO) system are provided. A first indication of signal quality (ISQ) is received at the access point from a first station and a second ISQ is received from a second station. The access point sets a first power level and a first modulation and coding scheme (MCS) for transmission of a first aggregated media access control (MAC) protocol data unit (A-MPDU) to the first station as a function of the first ISQ and an amount of payload data corresponding to the first A-MPDU. The access point also sets a second power level and a second MCS for transmission of a second A-MPDU as a function of the second ISQ and an amount of payload data corresponding to the second A-MPDU.

42 citations


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