Performance analysis of antenna array calibration and its impact on beamforming: A survey

Multiple antennas techniques have been widely adopted in broadband wireless communication systems to enhance spectral efficiency and achieve space diversity gain. Transmitter beamforming is one of promising multiple antenna techniques for IMT-Advanced system, which takes advantage of directional signal transmission or reception. For efficient transmitter beamforming, TDD (Time Division Duplex) system has an inherit advantage to exploit the channel reciprocity between uplink and downlink, and no additional channel feedback is needed. However, the mismatches of actual RF (ratio frequency) channel may cause channel non-reciprocity. This paper presents the latest progress on multiple antenna calibration, including the analysis of the hardware error characteristics, typical statistical models of the calibration error (CE), and the impacts on downlink beamforming due to CE. Furthermore, we present the performance analysis and comparison for widely used Base Station (BS) based calibration schemes. Finally, several possible terminal based calibration schemes are summarized to compensate the actual RF mismatches.