Compensation of Phase Noise in Uplink Massive MIMO OFDM Systems

Due to the imperfection of practical oscillators, phase noise (PHN) inevitably occurs in the phase of desired signals, and may incur significant degradation in the performance of wireless communications. This paper addresses the PHN compensation in uplink massive multiple-input multiple-output orthogonal frequency division multiplexing systems, where multiple single-antenna users simultaneously communicate with a base station equipped with a large antenna array. The proposed compensation scheme considers a two-stage transmission protocol. In the first stage, training symbols are transmitted, and the channels of multiple users are estimated along with the PHN sequences involved. In the second stage, information-conveying data symbols are transmitted, and the channel estimates previously obtained are used to estimate the data symbols in the presence of unknown PHN. For both stages, the estimation methods are elaborately derived based on the variational expectation maximization methodology. Moreover, some simplifications are conducted to significantly reduce the computational complexity of the proposed scheme. The effectiveness of the proposed PHN compensation scheme is corroborated through extensive simulations.