Improving TCP performance by congestion window adaptation MANET

Abstract

An ad hoc network is a dynamically forming temporary network with a collection of wireless mobile nodes. It does not use any centralized administration or existing network infrastructure. In wireless networks, improving TCP performance largely depends on congestion window size. Both contention and congestion affect the TCP performance. A contention problem occurs in network when adjacent nodes shared channel to transmit packets. Channel contentions cause network congestion because of a lack of coordination between the transport layer and the medium access layer. Due to the channel interference the Bandwidth Delay Product cannot reach to maximum value as in wired network. Packet loss occurs at MAC layer due to congestion. In ad hoc networks, both contention and congestion can severely affect the performance of TCP. In our work, we show that the over-injection of conventional TCP window mechanism results in severe contentions, and medium contentions cause network congestion. The idea is to dynamically adjust the congestion window to improve TCP performance by reducing the congestion window overshooting problem. We study the network performance such as throughput, Packet delivery ratio, and end-to- end delay when congestion control mechanism is used.