Investigating TCP Performance in Mobile Ad Hoc Networks

This volume deals with the performance issues of TCP when used over Mobile Ad Hoc Networks (MANETs). Although other works in the past have dealt with this topic, many of these have proposed inter-layer changes, usually in the transport and link layers, and often break compatibility with existing TCP implementations, violate end-to-end semantics, or are otherwise too invasive to be gradually deployed. This work proposes techniques to improve the performance of the most widely deployed TCP agents (i.e. the Reno, NewReno and SACK variants), ensures that all changes are implementable at the transport layer, and offers interoperability with traditional implementations. Overall, the work has three main themes. Firstly, an evaluation of TCP performance over medium size MANETs is presented, utilising four types of agents (Reno, NewReno, SACK and Vegas). By drawing inspiration from the results, the second and third themes propose mechanisms to improve TCP performance by implementing changes on the sending and receiving sides of the communicating pair respectively. Throughout the study, design choices are clearly justified and potential implementation issues are highlighted and discussed.