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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
24 Apr 2014
TL;DR: This paper is interested in all-wireless systems which are severely constrained in the amount of information that can be exchanged among the cooperating nodes, in contrast to recent proposals in massive MIMO (co-located antennas) or base station cooperation (which relies on a high-speed wired backhaul).
Abstract: Making MIMO truly “massive” involves liberating it from the shackles of form factor constraints, by allowing arbitrarily large groups of neighboring nodes to opportunistically form virtual antenna arrays for both transmission and reception. Moving such distributed MIMO (DMIMO) systems from the realm of information theory to practice requires synchronization of the cooperating nodes at multiple levels. We are interested in all-wireless systems which are severely constrained in the amount of information that can be exchanged among the cooperating nodes, in contrast to recent proposals in massive MIMO (co-located antennas) or base station cooperation (which relies on a high-speed wired backhaul). The goal of this paper is to point out some of the research issues unique to scaling up such DMIMO systems. We briefly review the significant technical progress in design and demonstration over the past few years, and describe a research agenda for the next few years based on fundamental questions in attaining the “distributed coherence” required to realize concept systems such as DMIMO communication at large carrier wavelengths (e.g., white space frequencies for which standard antenna arrays are too bulky) and distributed 911 for emergency and rescue scenarios.

76 citations

Proceedings ArticleDOI
06 Nov 2005
TL;DR: A routing protocol called MIR is proposed for ad-hoc networks with MIMO links, that leverages the various characteristics of MIMo links in its mechanisms to improve the network performance and is shown to be effective through ns2 simulations.
Abstract: Smart antennas include a broad variety of antenna technologies ranging from the simple switched beams to the sophisticated digital adaptive arrays. While beam-forming antennas are good candidates for use in strong line of sight (LOS) environments, it is the multiple input multiple output (MIMO) technology that is best suited for multipath environments. In fact, the MIMO links exploit the multipath induced rich scattering to provide high spectral efficiencies. The focus of this work is to identify the various characteristics and tradeoffs of MIMO links that can be leveraged by routing layer protocols in rich multipath environments to improve their performance. To this end, we propose a routing protocol called MIR for ad-hoc networks with MIMO links, that leverages the various characteristics of MIMO links in its mechanisms to improve the network performance. We show the effectiveness of the proposed protocol by evaluating its performance through ns2 simulations for a variety of network conditions.

76 citations

Proceedings ArticleDOI
30 Sep 2013
TL;DR: NEMOx organizes a network into practical-size clusters, each containing multiple distributed APs (dAPs) that opportunistically synchronize with each other for netMIMO downlink transmission for large-scale wireless networks.
Abstract: Network MIMO (netMIMO) has potential for significantly enhancing the capacity of wireless networks with tight coordination of access points (APs) to serve multiple users concurrently. Existing schemes realize netMIMO by integrating distributed APs into one ``giant'' MIMO but do not scale well owing to their global synchronization requirement and overhead in sharing data between APs. To remedy this limitation, we propose a novel system, NEMOx, that realizes netMIMO downlink transmission for large-scale wireless networks. NEMOx organizes a network into practical-size clusters, each containing multiple distributed APs (dAPs) that opportunistically synchronize with each other for netMIMO downlink transmission. Inter-cluster interference is managed with a decentralized channel-access algorithm, which is designed to balance between the dAPs' cooperation gain and spatial reuse---a unique tradeoff in netMIMO. Within each cluster, NEMOx optimizes the power budgeting among dAPs and the set of users to serve, ensuring fairness and effective cancellation of cross-talk interference. We have implemented and evaluated a prototype of NEMOx in a software radio testbed, demonstrating its throughput scalability and multiple folds of performance gain over current wireless LAN architecture and alternative netMIMO schemes.

76 citations

Journal ArticleDOI
TL;DR: The design of linear transceivers for multiple-input-multiple-output (MIMO) communication systems with channel state information is particularly challenging for two main reasons, and the present work addresses this problem by combining the closed-form solutions for single MIMO channels with a primal decomposition approach.
Abstract: The design of linear transceivers for multiple-input-multiple-output (MIMO) communication systems with channel state information is particularly challenging for two main reasons. First, since several substreams are established through the MIMO channel, it is not even clear how the quality of the system should be measured. Second, once a cost function has been chosen to measure the quality, the optimization of the system according to such criterion is generally difficult due to the nonconvexity of the problem. Recent results have solved the problem for the wide family of Schur-concave/convex functions, resulting in simple closed-form solutions when the system is modeled as a single MIMO channel. However, with several MIMO channels (such as in multi-antenna multicarrier systems), the solution is generally more involved, leading in some cases to the need to employ general-purpose interior-point methods. This problem is specifically addressed in this paper by combining the closed-form solutions for single MIMO channels with a primal decomposition approach, resulting in a simple and efficient method for multiple MIMO channels. The extension to functions that are not Schur-concave/convex is also briefly considered, relating the present work with a recently proposed method to minimize the average bit error rate (BER) of the system.

76 citations

Journal ArticleDOI
TL;DR: In this paper, a compact antenna system for diversity/multiple-input-multiple-output (MIMO) application is proposed for WLAN (5.8 GHz) band with good isolation between the two input ports.
Abstract: In this letter, a novel compact antenna system for diversity/multiple-input–multiple-output (MIMO) application is proposed for WLAN (5.8 GHz) band with good isolation between the two input ports. The novelty of the proposed MIMO antenna system is, though the resonators are physically separated by a distance of $0.029\lambda $ ( $\lambda $ is the free-space wavelength at 5.8 GHz) equal to the thickness of the substrate (1.524 mm) used for the fabrication of the antenna system, the isolation between them is enough for practical application of the antenna for MIMO. The MIMO system possesses good pattern diversity and polarization diversity with good isolation without the use of any isolation enhancement techniques. Moreover, the concept can be extended to the realization of an MIMO antenna system to operate at other frequencies with suitable scaling and optimization of geometrical parameters of the antenna topology.

76 citations


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