Performance of Multi-Cell Massive MIMO Systems With Interference Decoding

TL;DR

This paper investigates advanced interference decoding schemes in multi-cell massive MIMO systems, demonstrating they can achieve unbounded rates as the number of antennas grows, outperforming traditional interference treatment methods.

Contribution

It introduces and analyzes simultaneous decoding schemes like SD and SND, showing they can mitigate pilot contamination effects and improve system capacity.

Findings

SND achieves unbounded rate as antennas increase.

SND outperforms TIN for finite antennas.

Proposed schemes improve system performance numerically.

Abstract

We consider a multi-cell massive MIMO system where a time-division duplex protocol is used to estimate the channel state information via uplink pilots. When maximum ratio combining (MRC) is used at the BSs, the re-use of pilots across cells causes the pilot contamination effect which yields interference components that do not vanish as the number of base-station (BS) antennas $M \rightarrow \infty$. When treating interference as noise (TIN), this phenomenon limits the performance of multi-cell massive MIMO systems. In this paper, we analyze more advanced schemes based on simultaneous unique decoding (SD) as well as simultaneous non-unique decoding (SND) of the interference that can provide unbounded rate as $M \rightarrow \infty$. We also establish a worst-case uncorrelated noise technique for multiple-access channels to derive achievable rate expressions for finite $M$. Furthermore, we study a much simpler subset of SND (called S-SND) which provides a lower bound to SND and achieves unbounded rate as $M \rightarrow \infty$, and also outperforms SD for finite $M$. For the special cases of two-cell and three-cell systems, using a maximum symmetric rate allocation policy we compare the performance of different interference decoding schemes with that of TIN. Finally, we numerically illustrate the improved performance of the proposed schemes.