Network MIMO system calibration with non-ideal channel reciprocity

摘要

This paper studies the channel reciprocity calibration problem based on minimum mean square error (MMSE) in a 7-Cell network multiple-input and multiple-output (MIMO) system. Network MIMO system can mitigate the inter-cell interference by joint precoding techniques. However, mismatches between the transceiver modules of the antennas destroy the channel reciprocity in time division duplex (TDD) mode. Therefore the mismatches should be calibrated before channel reciprocity can be used. An effective method for calculating the calibration coefficients in the network MIMO system whose base stations (BSs) are equipped with multiple antennas is proposed. The 7-Cell network MIMO system is divided into 7 independent centralized MIMO systems and one distributed MIMO system, then the calibration coefficients of the two systems can be brought together to calculate the calibration coefficients of the 7-Cell network MIMO system. The validity of the method is evidenced by the simulation results.