Impact of Inter-Cell Interference on Sum-Rate-Based Array Layout Design for Massive MIMO

Irregular, sparse array antennas deployed at base stations (BSs) in massive MIMO systems have been shown to yield a higher sum rate compared to conventional uniform half-wavelength spaced arrays. However, these results have been obtained for single-cell models, i.e., in the absence of inter-cell interference (ICI). In this paper, we propose an interference-region-extended single-cell model and we investigate the impact of ICI on array layout design. First, we show that sum rate gains achieved by irregular, sparse array antennas disappear in scenarios with ICI. Instead, uniformly spaced arrays yield the highest sum rates in these scenarios. Second, we show that sum rate gains of irregular arrays can be recovered and in some cases even increased compared to the single-cell scenario through coordinated beamforming.