Cross-Layer Design of MIMO OFDM with Mode Switching and Hybrid ARQ

We developed a cross-layer scheme for Turbo coded MIMO OFDM systems enhanced by adaptive MIMO mode switching and hybrid automatic repeat request (HARQ). At the physical layer, we use space frequency block codes (SFBC) and Bell Labs layered space time (BLAST) codes for MIMO mode switching. A type-II HARQ mechanism is considered at the data link layer during which MIMO mode switching is proposed to be used not only in the original transmission but also in retransmissions. Throughput performance of the cross-layer scheme is evaluated under a 3GPP Long Term Evolution frame structure. Simulation results reveal that the MIMO OFDM system with adaptive mode switching and HARQ can achieve good throughput performance. In particular, the HARQ scheme with adaptive mode retransmission achieves better performance than that of HARQ scheme with non-adaptive mode retransmission.