Electrical and Computer Engineering Department-College of Engineering-Sultan Qaboos University
Performance Evaluation of TCP in Wireless Mobile Ad Hoc Networks (MANETs)
Aziza Najib AL-Zadjali
Abstract
The rapid advancement in portable computing platforms and wireless communication technology
has led to significant interest in the design and development of protocols for instantly deployable
wireless networks, often referred to as Mobile Ad- Hoc Networks (MANETs). Transmission
Control Protocol (TCP)can suffer a significant drop in its throughput when it runs on MANETs.
This poor performance is because of the TCP implicit assumption that any packet loss is due to
congestion, which causes TCP to invoke its congestion control algorithm. This assumption is true
in wired networks, but not true in MANETs. Several protocols have been proposed for improving
TCP throughput over standalone MANETs. Moreover, routing protocols for MANETs have been
divided in distinct categories including reactive and proactive.
In this study, we present a comprehensive evaluation of TCP to understand the performance
behavior of TCP variants in different MANET scenarios for a variable amount of traffic load and
network sizes. Four different TCP variants, namely Tahoe, Reno New Reno and Vegas over two
well-known routing protocols; Ad hoc On-Demand Distance Vector (AODV) and Destination
Sequenced Distance Vector (DSDV),are evaluated for different system scenarios. The
performance measures used to evaluate the TCP variants are mainly throughput and packet
delivery ratios. Conclusions will be drawn based on the simulation results and the comparisons
between them will be elaborated.
The simulations in this work have revealed that in general it is quite hard to say which particular
TCP variant is best under which routing protocol since performance depends on the network
conditions. This is because the results have shown that one TCP variant under AODV performs
better in certain conditions and in other conditions, the same TCP variant under DSDV achieves
better results. Nevertheless, it can be concluded from the obtained results and analysis that TCP
Vegas under DSDV routing protocol is the best choice for the network topology used in this
project with the default input parameters used in the simulations (e.g., speed: 10m/s, number of
nodes: 50, pause time: 0 and number of connections: 30).