On the Spectral Efficiency of Noncooperative Uplink Massive MIMO Systems

TL;DR

This paper analyzes the spectral efficiency of uplink massive MIMO systems, showing that joint decoding schemes outperform traditional separate decoding, especially under high interference, and provides theoretical and simulation results to support this.

Contribution

It introduces and evaluates joint decoding schemes for uplink massive MIMO, demonstrating their superior spectral efficiency over conventional methods.

Findings

Joint decoding schemes achieve higher ergodic rates.

Standard separate decoding underestimates achievable rates.

Performance gains are significant in interference-dominant scenarios.

Abstract

Massive multiple-input multiple-output (MIMO) systems have been drawing considerable interest due to the growing throughput demands on wireless networks. In the uplink, massive MIMO systems are commonly studied assuming that each base station (BS) decodes the signals of its user terminals separately and linearly while treating all interference as noise. Although this approach provides improved spectral efficiency which scales with the number of BS antennas in favorable channel conditions, it is generally sub-optimal from an information-theoretic perspective. In this work we characterize the spectral efficiency of massive MIMO when the BSs are allowed to jointly decode the received signals. In particular, we consider four schemes for treating the interference, and derive the achievable average ergodic rates for both finite and asymptotic number of antennas for each scheme. Simulation tests of the proposed methods illustrate their gains in spectral efficiency compared to the standard approach of separate linear decoding, and show that the standard approach fails to capture the actual achievable rates of massive MIMO systems, particularly when the interference is dominant.