On antenna calibration for the TDD-based network MIMO system

Antenna calibration to enhance the channel reciprocity between the uplink and downlink channels is necessary for the practical wireless system operating in the time division duplexing (TDD) mode. This paper investigates on the computation of the antenna calibration coefficients of the cooperative base stations´ antennas in the network multiple-input and multiple-output (MIMO) system. An efficient scheme for computing the calibration coefficients for an arbitrary number of distributed antennas is proposed. In addition, we also propose two methods of refining the calibration coefficients for the proposed scheme. The evaluations of the proposed scheme and methods are performed through computer simulations.