Analysis on the impact of antenna gain mismatch on precoding vector

Antenna gain mismatch between transmitter and receiver circuits has been regarded as an obstacle for exploiting channel reciprocity between uplink and downlink channels in time-division duplex (TDD) multiple-input multiple-output (MIMO) systems. To the best knowledge of the authors, little work to date has been on about the impact of antenna mismatches on the precoding vector. Motivated by this fact, this paper investigates some characteristics of downlink precoding in the presence of non-ideal antenna gains. Specifically, properties about inter-MS interference when mismatches exist at the base station (BS) side are presented as well as the perturbation of non-normalized precoding vector caused by mismatches at the mobile station (MS) side under two kinds of linear precoding algorithms. These properties are mostly irrelevant to specific distributions of antenna mismatch parameters and can help to provide a deeper insight into the antenna gain mismatch problem and the corresponding calibration.