Enhancing Quality of Service over 802.16 Network using Variants of TCP

Wireless networks are generally less efficient and unpredictable compared to wired networks, which make QoS provisioning a bigger challenge for wireless communications. The evergreen demand for fast delivery of large volumes of data is one of the challenging task for wireless communication technology. WiMAX is a wireless broadband solution that offers a rich set of features with a lot of flexibility in terms of deployment options and potential service offerings. Its main objective is to provide quality with cost effectiveness. But Delivering QoS is more challenging for mobile broadband than for fixed. The time variability and unpredictability of the channel become more acute, and complication arises from the need to hand over sessions from one cell to another as the user moves across their coverage boundaries. WiMAX to provide high-speed access to the Internet where the transmission control protocol (TCP) is the core transport protocol. Unlike routing, where packets are relayed hop-by-hop toward their destination, TCP actually provides reliable end to-end transmission of transport-level segments from source to receiver. As TCP was designed for wired networks it considers that all packet loss in the network is due to congestion. Wireless medium is more exposed to transmission errors and sudden topological changes. So in this thesis work, we investigate the effects of subscriber’s mean speed on the performance characteristics of three representative TCP schemes, namely TCP-New Reno, Westwood and Cubic, in WiMAX network environment, under the conditions of correlated lossy links, route failures and network congestion using ns2.