IMPLEMENTATION OF DATAGRAM CONGESTION CONTROL PROTOCOL FOR MOBILE AD HOC NETWORKS

Abstract

Wireless and mobile ad-hoc networks are expected to play an important role in future civilian and military where wireless access to wired networks is ineffective and almost impossible. These are all due to the growth of technology in wireless communications and the popularity gained by the portable computing devices. Wireless networks are going to be pervasive, and hence it is almost impossible to keep ourselves away from this technology. MANET is a self-configuring network that is formed by the combination of mobile nodes and is operated without the aid of any centralized management. The nodes that are not within the radio range communicate with the help of intermediate nodes in order to forward;their messages. It is very difficult to quickly change the transmission rate according to the changes of communication environment when a mobile host transmitting real-time traffic moves between two wireless LAN access points with different congestion situations. Also the demand for timely delivery of data is increased as compared to the reliability for the multimedia applications. UDP and TCP are generally used as the transport. protocol to transfer the data over the IP based network like Internet. Experiments and research have shown that both TCP and UDP perform very poorly over wireless ad-hoc networks with degraded throughput and severe unfairness among flows.TCP provides a reliable mechanism to transfer the data but its reliability ,increases delay, and, though UDP's unreliable behavior provides less delay to transfer the data, it lacks 'congestion control mechanisms. In this dissertation, we proposed DCCP that have specially designed congestion control algorithms, for mobile ad-hoc networks in order to support multimedia applications and implemented this congestion control - algorithm on NS2. Simulations are performed and the performance of this transport protocols are analyzed in terms of performance metrics like packet delivery ratio and -throughput. With the help of these performance metrics, it is found that the performance of DCCP is much better as compared to -UDP and TCP. UDP -degrades . the quality of multimedia applications because of less throughput and large number of packet loss.