Hybrid ARQ scheme suitable for coded MIMO transmission

An automatic-repeat-request (ARQ) scheme for improving the system throughput efficiency is investigated in coded multiple-input multiple-output (MIMO) transmissions. The improved ARQ scheme employs two strategies, referred to as trellis-coded modulation (TCM) reassignment and antenna permutation. TCM reassignment increases the free distance after code combining through the use of different TCM codes for retransmissions. Antenna permutation exploits spatial dimension for preventing successive frame errors by changing the connections between transmitters and transmit antennas upon retransmission. It is shown through computer simulations that this ARQ scheme achieves high throughput even in severe conditions of low signal-to-noise ratio and high Rician factor over spatially and temporally correlated Nakagami-Rice fading MIMO channels.