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.

Ergodic Spectral Efficiency in MIMO Cellular Networks

Abstract: This paper shows how the application of stochastic geometry to the analysis of wireless networks is greatly facilitated by (i) a clear separation of time scales, (ii) the abstraction of small-scale effects via ergodicity, and (iii) an interference model that reflects the receiver's lack of knowledge of how each individual interference term is faded. These procedures render the analysis both more manageable and more precise, as well as more amenable to the incorporation of subsequent features. In particular, the paper presents analytical characterizations of the ergodic spectral efficiency of cellular networks with single-user multiple-input multiple-output (MIMO) and sectorization. These characterizations, in the form of easy-to-evaluate expressions, encompass the coverage, the distribution of spectral efficiency over the network locations, and the average thereof.

A relaying scheme using QR decomposition with phase control for MIMO wireless networks

Abstract: Multiple-input multiple-output (MIMO) wireless networks are wireless communication systems composed of multiple nodes, each of which is equipped with multiple antennas. As proven by earlier studies, point-to-point MIMO systems offer significant capacity through spatial multiplexing and diversity techniques. Furthermore, recent studies have shown that the capacity of MIMO wireless networks can be greatly improved by using multiple relay nodes to relay messages simultaneously from source to destination. This paper proposes a relaying scheme for MIMO wireless networks. Its major concepts are: 1) performing QR decomposition on backward and forward channels in conjunction with phase control at each relay node, and 2) conducting successive interference cancellation (SIC) at the destination node. Such operations enable the wireless network to obtain distributed array gain among multiple relay nodes and receive array gain while maintaining maximum spatial multiplexing gain. Numerical examples have shown that the proposed relaying scheme is superior to previously proposed ones in both ergodic and outage capacity perspective.

Capacity of Wireless Communication Systems Employing Antenna Arrays, a Tutorial Study

Abstract: A tutorial study is performed on the capacity of multiple antenna wireless communication systems. Multiple antenna structures can be classified into single-input multiple-outputs (SIMO), multiple-inputs single-output (MISO), and multiple-inputs multiple-outputs (MIMO) systems. Assuming that the channel is known at receiver, capacity expressions are provided for each structure, under the conditions of quasi-static flat fading. Also, information rate limits are provided in each case for some suboptimal structures or detection techniques that may be used in practice. Using simulations for the case of flat Rayleigh fading, capacities of optimal/suboptimal implementations are contrasted for each multi-antenna structure. Discussions are made on system design, regarding implementation complexity and practical limitations on achieving these capacities. In particular, the problem of fading correlation and required antenna spacing, effect of fast channel fading, and lack of channel knowledge at receiver are discussed. Providing the results of the most recent researches considering the capacity of multi-antenna systems, as well as some new results, this paper can give a good perspective for designing appropriate architectures in different wireless communication applications.

System and method for incorporating dynamic orthogonal frequency-division multiplexing into wireless network protocols

Abstract: A method for incorporating dynamic orthogonal frequency-division multiplexing (“OFDM”) in wireless networks is provided. Information about a wireless channel between a transmitter and one or more receivers communicating according to a wireless protocol is acquired. Dynamic OFDM allocations are generated based on the acquired information about the wireless channel. The dynamic OFDM allocations are transmitted to the one or more receivers according to the wireless protocol.

Delay spread properties in a measured massive MIMO system at 2.6 GHz

Abstract: Massive multiple-input multiple-output (MIMO) systems, where the base station (BS) is equipped with a large number of antennas and the mobile devices have a single antenna, can significantly enhance the system performance. In many wireless systems inter symbol interference (ISI) due to delay dispersion of the channel can dramatically affect the demodulation process of the received signals. Precoding in massive MIMO can reduce or eliminate ISI, while still exploiting the spatial diversity. In this paper, we investigate how much standard linear precoders help the ISI mitigation by shortening the rms delay spread. In order to evaluate the system performance, we measured a massive MIMO channel with 128 antennas at the base station and 36 users, including 26 line-of-sight and 10 non line-of-sight, each equipped with a single antenna. We also compare the results from the measurements with an independent identically distributed Gaussian channel with an exponentially decaying average power delay profile.