Successive Block Diagonalization Precoding for Multi-User MIMO System

Abstract:

Block Diagonalization (BD) is a common linear precoding technique for the downlink of multi-user MIMO(MU-MIMO) systems. A drawback of conventional BD is that the effective channel gain for each data stream can be severely unbalanced when each user has multiple data streams. In this paper, a new precoding scheme called successive BD (SBD) is proposed based on BD precoding by introducing a new construction scheme of interference matrices considering inter-antenna interference. The precoding matrix responding to each of the receive antennas is successively calculated. SBD precoding reduces the difference in effective channel gain between each user’s multiple data streams caused by the original BD precoding and improves the average bit error performance of the user. More spatial diversity gain can be obtained compared with BD precoding when precoding and combing are employed and spatial diversity transmission strategy is adopted. Simulations show that when the bit error rate is 10^(-3), the proposed method has about 2 dB gain over the conventional BD precoding in {2,2}*4 MU-MIMO systems.