Novel HARQ schemes for MIMO single-hop and Multi-hop relay systems

Abstract

Multiple Input Multiple Output (MIMO) systems use multiple transmit and receive antennas to achieve higher data rates by transmitting multiple independent data systems. Transmission errors can be reduced by using Hybrid Automatic Repeat request (HARQ) combining techniques with MIMO systems. We propose two novel MIMO HARQ combining methods which are based on using pre-combining only and a joint post and pre-combining techniques. In addition to conventional direct transmission, HARQ schemes for MIMO Multi-hop relay systems are also investigated. A novel approach is proposed to deal with the parallel HARQ processes in MIMO relay scenario. The simulation results show that the proposed methods can enhance the overall throughput performance of MIMO Single-hop and multi-hop relay systems.