Cross-Layer TCP Performance Enhancement Technique in OFDM System
Ping Zhang · Journal of Jilin University · 2007
CLTCP(Cross-Layer Transport Control Protocol) enhancement technique in OFDM(Orthogonal Frequency Division Multiplexing) system is proposed to improve the wireless TCP(Transport Control Protocol) performance.The main idea of CLTCP is the link recovery and Freezing-TCP.The link layer will retransmit the error frames for limited times,which can conquer the decrease of throughput caused by congestion control in TCP layer.Simultaneously,AMC(Adaptive Modulation and Coding) is adopted to improve the retransmission reliability,that the error frames can be sent to the receiver correctly in limited times.Freezing-TCP technique is adopted to freeze the RTO(Retransmission Time Out) value in the TCP source side,which can avoid the huge RTO value caused by continuous expiration of retransmission timer when the air link disconnection happens,the TCP layer can work immediately after the air link recovers.Multiple wireless TCP schemes are simulated in NS2(Network Semulation 2),the simulation shows that CLTCP scheme can improve 33% of the maximum throughput compared to the snoop scheme,while reduces 38% of the air bandwidth.