Impact of TCP Variants on the Performance of AODV MANET Routing Protocol

Abstract

With recent performance advancements in computer and wireless communications technologies, advanced mobile wireless computing is having increasingly widespread use and applications, much of which will involve the use of the Internet Protocol suite. The vision of mobile ad hoc networks (MANETs) is to support robust and efficient operation in mobile wireless networks by incorporating routing functionality into mobile nodes. Such networks are envisioned to have dynamic, sometimes rapidly-changing, random, multi-hop topologies which are likely composed of relatively bandwidth-constrained wireless links. With the proliferation of inexpensive and portable computing devices, everyone wants to connect with the Internet on the go. Most of the Internet traffic is based on connection oriented transport layer protocol, i.e., „transmission control protocol‟ (TCP) that has been designed to provide reliable data transmission in wired networks. For the smooth integration of a MANET with Internet, the performance of TCP must be acceptable in MANET. Constant bit rate (CBR) traffic patterns over UDP are mainly used for the evaluation of MANET routing protocols whereas most of the application layer protocols such as http, ftp, smtp and telnet etc are based on TCP that has different characteristics than that of UDP/CBR. Therefore, it is essential, before selecting a specific MANET routing protocol to be used in MANET, to analyze the effect of TCP traffic patterns on the performance of that MANET routing protocol. In this paper, the effect of different TCP variants have been analyzed on Ad hoc On Demand Distance Vector MANET Routing (AODV) Protocol which is one of the most widely used standard MANET routing protocol. The impact has been analyzed by varying pause time of the node movements. There is significant difference between the performance of AODV depending upon the traffic patterns. CBR is useful for the stress testing of a MANET whereas TCP is more realistic Internet traffic pattern.