TCP Selective Negative Acknowledgment over IEEE 802.11 Wireless Networks

This paper investigates the performance of the TCP transport protocol over IEEE 802.11 wireless networks. A wireless link is generally characterized by high transmission errors and a varying latency. The erratic packet losses and poor bandwidth utilization which occur as a result limit the TCP's performance, resulting in a curbing of the flow of segments on the TCP connection and a corresponding degradation of the network performance. This paper examines the effects of the 802.11 characteristics on the TCP performance and proposes a scheme to improve the performance of TCP over wireless links. A novel acknowledgement scheme, SNACK, is introduced and a series of ns-2 based simulations are performed to compare its performance against that of other TCP schemes. The simulation results confirm that SNACK provides a better performance than other conventional TCP implementations in 802.11 wireless networks.