Hop Aware Scheduling Algorithm for TCP Performance Enhancement in Multi Hop Relay WiMAX

Mobile Multi-hop Relay (MMR) WiMAX networks allow the number of hops between the user and the MMR-BS to be more than two hops when the non transparent relay station is used. Transmission Control Protocol (TCP) protocol is optimized to be used in wired networks where the main cause of loss is the congestion. TCP throughput is highly affected by packet losses or timeout occurrences because of its congestion control mechanism. Upon the occurrence of timeout, TCP decreases the transmission window which results in throughput degradation, even if such losses are not due to congestion. This paper presents link layer scheduling algorithm to enhance the TCP in IEEE 802.16j MMR WiMAX networks. The aim is to reduce the Retransmission Timeout (RTO) occurrences and enhance the throughput. The results showed that the hop aware scheduling algorithm gives higher throughput, and less timeout occurrence for different BER values.