Uplink sum rate analysis of multi‐user massive MIMO–OFDM/OQAM systems in Ricean fading

Abstract

This study investigates the uplink performance of offset quadrature amplitude modulation (OQAM)-based orthogonal frequency division multiplexing (OFDM) waveform in single-cell multi-user massive multiple-input multiple-output (MIMO) systems over Ricean fading. An uplink training-based minimum mean square error (MMSE) channel estimation by exploiting the inherent characteristics of OFDM/OQAM waveform is briefly presented. By leveraging the second-order statistical characteristics of the intrinsic interference, the achievable uplink sum rates and corresponding closed-form approximations are derived in the presence of MMSE channel estimate at the base station with zero-forcing (ZF) and maximum-ratio combining (MRC) receivers. Based on the above analytical results for the uplink rates, power scaling laws are also investigated. The effect of Ricean-K factor on the achievable uplink sum rate is also examined analytically for both the MRC and ZF receivers. Numerical results compare the performance of OFDM/OQAM and classic cyclic-prefix OFDM-based massive MIMO systems and also validate the various analytical expressions derived in this work.