BER Analysis of Multi-Cellular MIMO Systems with Increasing Number of BS Antennas

TL;DR

This paper investigates the behavior of Massive MIMO systems as the number of base station antennas increases, revealing a fundamental relationship and analyzing BER performance under realistic impairments, highlighting pilot contamination as a key limiting factor.

Contribution

It provides a simple relationship for channel matrix behavior in Massive MIMO and analyzes BER performance considering practical impairments, emphasizing pilot contamination's impact.

Findings

Channel matrix product tends to a scaled identity as antennas increase

BER performance is limited by pilot contamination even with infinite antennas

The relationship supports assumptions used in Massive MIMO analysis

Abstract

In this work, salient characteristics of a wireless communication system deploying a great number of antennas in the base station (BS), namely Massive MIMO system, are investigated. In particular, we found a simple and meaningful relationship that corroborates a fundamental assumption in recent related works: according the number of BS antennas $N$ grows, the product of the small-scale fading channel matrix with its conjugate transpose tends to a scaled identity, with a variability measure inversely proportional to $N$. Furthermore, analysis of the Massive MIMO system downlink is carried out from a bit-error-rate (BER) performance viewpoint, including some realistic adverse effects, such as interference from neighboring cells, channel estimation errors due to background thermal noise, and pilot contamination, which was recently shown to be the only impairment that remains in the MIMO multicell system with infinite number of BS antennas. Our numerical result findings show that, in the same way as with the sum capacity, the pilot contamination also limits the BER performance of a noncooperative multi-cell MIMO system with infinite number of BS antennas.