Analysis and modeling of channel reciprocity errors based on a experimental OFDM/TDD coordinated multi-point transmission system

According to the real channel measurement in the experimental OFDM/TDD coordinated multipoint (CoMP) system, we analyze the reciprocity error issue in this paper. A mathematical model is proposed to depict the characteristics of the reciprocity error in time and frequency domain, which is caused by the asymmetrical timing synchronization offset and the residual frequency synchronization offset. The model is in good agreement with the measured data. The simulation result based on the measured data shows that the reciprocal errors significantly degrade the performance of the downlink precoding algorithm in OFDM/TDD CoMP system.