Deployment of Fair Share and Smart Start Technique for Optimal Use of Available Capacity in TCP Congestion Control

TCP (Transmission Control Protocol) (1) was designed to provide reliable end-to-end delivery of data over unreliable networks. In theory, TCP should be independent of the technology of the underlying infrastructure. In particular, TCP should not care whether the Internet Protocol (IP) is running over wired or wireless connections. In practice, it does not matter because most TCP deployments have been carefully designed based on assumptions that are specific to wired networks. Ignoring the properties of wireless transmission can lead to TCP implementations with poor performance. In wireless and Ad hoc networks, the principal problem of TCP lies in performing congestion control in case of losses that are not induced by network congestion. Since bit error rates are very low in wired networks, nearly all TCP versions nowadays assume that packets losses are due to congestion. Consequently, when a packet is detected to be lost, either by timeout or by multiple duplicated acknowledgements (ACK), TCP slows down the sending rate by adjusting its congestion window. Unfortunately, wireless networks suffer from several types of losses that are not related to congestion, making TCP not adapted to this environment. Numerous enhancements and optimizations have been proposed over the last few years to improve TCP performance over wireless and Ad hoc Networks. These improvements include infrastructure based WLANs (2), (3), ( It is noted that the following TCP versions: Tahoe, Reno, Newreno, and Vegas perform differently in Ad hoc networks (10). However, all these versions suffer from the