  We consider the downlink of a multi-cell massive MIMO system suffering from
asymptotic rate saturation due to pilot contamination. As opposed to treating
pilot contamination interference as noise (TIN), we study the performance of
decoding the pilot contamination interference. We model pilot-sharing users as
an interference channel (IC) and study the performance of schemes that decode
this interference partially based on rate-splitting (RS), and compare the
performance to schemes that decode the interference in its entirety based on
simultaneous unique decoding (SD) or non-unique decoding (SND). For RS, we
non-uniquely decode each layer of the pilot contamination interference and use
one common power splitting coefficient per IC. Additionally, we establish an
achievable region for this RS scheme. Solving a maximum symmetric rate
allocation problem based on linear programming (LP), we show that for
zero-forcing (ZF) with spatially correlated/uncorrelated channels and with a
practical number of BS antennas, RS achieves significantly higher spectral
efficiencies than TIN, SD and SND. Furthermore, we numerically examine the
impact of increasing the correlation of the channel across antennas, the number
of users as well as the degree of shadow fading. In all cases, we show that RS
maintains significant gain over TIN, SD and SND.
