Inter-cell antenna calibration for TDD CoMP systems

Coordinated Multi-Point (CoMP) transmission is a promising technique to suppress inter-cell interference, especially for TDD system which can easily get downlink channel information at evolved NodeB (eNB) through channel reciprocity. However, mismatches of radio frequency (RF) transmitter and receiver might affect channel reciprocity, thus make antenna calibration become a crucial issue. Intra-cell antenna calibration has already been studied for single cell systems. In this paper, an inter-cell antenna calibration method is proposed for TDD CoMP systems to efficiently compensate these mismatches. Differences between the inter-cell phase information feedback from users and that calculated based on uplink channel are used to get the mismatch coefficients. Simulation results demonstrate the proposed method can well compensate the RF channel mismatch, and TDD based CoMP technology can greatly improve the average and cell-edge spectral efficiency compared to the traditional cellular systems.