Spectral Efficiency of a Frequency-Selective Cell-Free Massive MIMO System With Phase Noise

Abstract

This letter studies spectral efficiency of a frequency-selective cell-free massive multiple-input-multiple-output (MIMO) system with phase noise (PN) and imperfect channel state information. Two linear and low-complexity receivers are considered, namely, time-reversal maximum-ratio combining (TR-MRC) and time-reversal large-scale fading decoding (TR-LSFD). For each receiver, a lower bound on the uplink achievable spectral efficiency (SE) is obtained. From the obtained bounds, it is found that, compared to the TR-MRC receiver, the TR-LSFD receiver can attain a higher SE and the performance gain of the TR-LSFD receiver depends on the number of access points (APs) and the propagation losses between APs and users. Numerical results are provided to corroborate the accuracy of our analysis and the performance superiority of TR-LSFD receiver. Results also show that the effect of PN at users is stronger than the effect of PN at APs on the achievable SE.