A Cut-Through Forwarding Scheme for Delay Optimization in IEEE 802.16j Simultaneous Transmit and Receive Multihop Relay Networks

The Simultaneous Transmit and Receive (STR) relaying is the most important feature as a Multi-hop Relay solution in WiMAX technologies to improve performance and extend coverage. This article contributes to the performance on unalignment modes in OFDM-based relay framework and applying in WiMAX standard which refer as IEEE 802.16j STR MAC. We proposed a cut-through scheme based on unalignment approach on OFDM-based symbol scheduling which provides lower forwarding latency per hop by shifting the alignment of frame duration between the super ordinate RS and subordinate RS (s), wherein the intermediate RS starts forwarding an OFMD frame before the whole frame has been received, normally as soon as the sub-frame is processed. Compared with legacy synchronous STR relaying, an unaligned STR relaying can provide a MS which is attached to the farthest RS, and still get a satisfied One Way Delay (OWD) and Round Trip Time (RTT). In addition, we demonstrate a significant performance improvement, the result shows the importance of defining unalignment approach of the OFDM-based multi-hop relaying topology.