Performance analysis of large-scale MU-MIMO with AF relaying in the presence of interference

Abstract

This paper analyzes the performance of a large-scale multiuser multiple-input multiple-output (MU-MIMO) system with amplify-and-forward (AF) relaying in the presence of cochannel interference. Each user terminal (UT) has a single antenna while the relay is equipped with very large antenna arrays. To evaluate the impact of large number of relay antennas on the performance of the considered system, we derive a lower bound on the achievable rate. We also perform a large system analysis in the regimes of high signal-to-noise ratio (SNR), large number of relay antennas and large number of UTs. Numerical results are presented to verify the theoretical analysis. I. INTRODUCTIONRecently, there has been a great deal of interest in multiuser multiple-input multiple-output (MU-MIMO) systems with large-scale antenna arrays at the base station. Through the use of a large excess of service antennas over the number of active user terminals (UTs), large-scale MU-MIMO can average out thermal noise, fast channel fading and some interference, thus bring huge improvements in throughput, spectrum efficiency and energy efficiency even with very simple linear receivers [1]- [5]. Though large-scale MU-MIMO system is a promising network architecture, there are still entirely new challenges that need further research in the design and analysis of the technology.On the other hand, relaying has also attracted significant attention in both academia and industry due to its numerous advantages. Most common relaying strategies proposed in the literature are decode-and-forward (DF) and amplify-andforward (AF). Among various relaying methods, AF relaying in particular is preferred for its simplicity and low-cost implementation. Moreover, AF relaying is capable of suppressing co-channel interference (CCI) in practice [6].An interesting practical scenario is that the relay is equipped with very large antenna arrays while each user terminal has a single antenna [7]. However, most of prior works deal with the case where all nodes are equipped with a single antenna, e.g. [8]. Also, in the context of single-antenna system, [9] investigated the impact of CCI on the performance of multi-hop AF relaying. Most recently, [10] analyzed a multipair full-duplex relaying system where the relay station is equipped with massive arrays, and [11] studied a multi-pair two-way AF relaying system with very large number of relay antennas. The limitations of [10] and [11] are the neglect of cochannel interferences in the system models.[12] investigated