Phase noise degradation in massive MIMO downlink with zero-forcing and maximum ratio transmission pre-coding

The effect of phase noise is considered in a downlink massive multiple-input-multiple-output (MIMO) scenario with linear precoding schemes, namely, zero-forcing (ZF) and maximum ratio transmission (MRT). The degradation in terms of signal-to-interference-plus-noise ratio (SINR) and the achievable rate are analytically obtained and compared with simulations. The effect of phase noise is different for the two linear precoding schemes, with MRT showing greater robustness but a lower achievable rate per user. Interestingly, the SINR degradation due to phase noise tends to be independent of the number of base-station antennas when this number is big enough. Moreover, the effects of imperfect channel knowledge at the transmitter are studied, and the comparison between the two precoders confirms greater robustness with MRT