Massive MIMO in Real Propagation Environments: Do All Antennas Contribute Equally?

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Abstract

Massive MIMO can greatly increase both spectral and transmit-energy efficiency. This is achieved by allowing the number of antennas and RF chains to grow very large. However, the challenges include high system complexity and hardware energy consumption. Here we investigate the possibilities to reduce the required number of RF chains, by performing antenna selection. While this approach is not a very effective strategy for
theoretical independent Rayleigh fading channels, a substantial reduction in the number of RF chains can be achieved for real massive MIMO channels, without significant performance loss. We evaluate antenna selection performance on measured channels at 2.6 GHz, using a linear and a cylindrical array, both having 128 elements. Sum-rate maximization is used as the criterion for antenna selection. A selection scheme based on convex optimization is nearly optimal and used as a benchmark. The achieved sum-rate is compared with that of a very simple scheme that selects the antennas with the highest received power. The power-based scheme gives performance close to the convex optimization scheme, for the measured channels. This observation indicates a potential for significant reductions of massive MIMO
implementation complexity, by reducing the number of RF chains and performing antenna selection using simple algorithms.

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Subject classification (UKÄ) – MANDATORY

  • Electrical Engineering, Electronic Engineering, Information Engineering

Keywords

  • large-scale fading, spatial diversity, multi-user MIMO, Massive MIMO, antenna selection, channel measurements, channel capacity, sum-rate, linear precoding, 5G
Original languageEnglish
Pages (from-to)3917-3928
JournalIEEE Transactions on Communications
Volume63
Issue number11
Publication statusPublished - 2015
Publication categoryResearch
Peer-reviewedYes

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