An Overview of Massive MIMO: Benefits and Challenges

Abstract

Massive multiple-input multiple-output (MIMO) wireless communications refers to the idea equipping cellular base stations (BSs) with a very large number of antennas, and has been shown to potentially allow for orders of magnitude improvement in spectral and energy efficiency using relatively simple (linear) processing. In this paper, we present a comprehensive overview of state-of-the-art research on the topic, which has recently attracted considerable attention. We begin with an information theoretic analysis to illustrate the conjectured advantages of massive MIMO, and then we address implementation issues related to channel estimation, detection and precoding schemes. We particularly focus on the potential impact of pilot contamination caused by the use of non-orthogonal pilot sequences by users in adjacent cells. We also analyze the energy efficiency achieved by massive MIMO systems, and demonstrate how the degrees of freedom provided by massive MIMO systems enable efficient single-carrier transmission. Finally, the challenges and opportunities associated with implementing massive MIMO in future wireless communications systems are discussed.

Adaptive Pilot Allocation Algorithm for Pilot Contamination Mitigation in TDD Massive MIMO Systems

“…Therefore, the channel estimate of the kth user at the lth BS becomes a linear combination of the channels to the kth users in all the other cells, causing what is known in literature as pilot contamination. It has been extensively shown in the literature, for example [3], [9], and [1], that with pilot contamination and when the number of BS antennas is very large (M → ∞), the uplink signal-tointerference-plus-noise ratio SINR of the kth user in the lth cell approaches the following limit…”

A mutual coupling model for massive MIMO applied to the 3GPP 3D channel model

“…They are a key part of today's wireless communication standards, such as IEEE 802.11 or 3rd Generation Partnership Project (3GPP) LTE-Advanced. In the last years, MIMO systems with a large number of antennas, referred to as massive MIMO, were considered in literature [1]- [4]. When the number of antennas approaches infinity, opportunities such as asymptotically orthogonal channels and utilization of linear receivers emerge.…”

A Method for Analyzing Broadcast Beamforming of Massive Mimo Antenna Array

“…It is the expansion and extension of the existing MIMO techniques of the 4G network [3][4][5][6][7][8][9][10][11][12][13][14][15]. Nowadays, the 4G cellular network supports simultaneous wireless transfer of maximum 8-ports [16], which is not enough to meet the requirements of future wireless data services.…”