Hybrid ARQ Scheme with Antenna Permutation for MIMO Systems in Slow Fading Channels

In this paper, an equivalent model for the hybrid automatic retransmission request (HARQ) multi-input multi-output (MIMO) systems with a proper combining scheme is first introduced. Based on this effective model, we present a simple technique, termed antenna permutation scheme (APS), which permutates the transmit antennas at each retransmission to improve the diversity gain from retransmissions in the slow fading environment. The theory analysis and simulation results demonstrate that the system with APS can achieve much better bit error performance.