MD NAZMUL ISLAM KHAN; RASHED AHMED MEE10:86, pp. 81. COM/School of Computing, 2010.
A Mobile Ad-hoc Network (MANET) is a collection of mobile devices dynamically forming a
communication network without any centralized control and pre-existing network infrastructure.
Due to the presence of mobility in the MANET, the interconnections between stations are likely
to change on a continual basis, resulting in frequent changes of network topology. Consequently,
routing becomes a vital factor and a major challenge in such a network. This research aims to
study the impact of four IETF (Internet Engineering Task Force) standardized routing protocols
on MANETs and thereby comprehensively analyzes their performance under varying network
sizes and node mobility rates. The four routing protocols that are considered in the analysis are
Optimized Link State Routing (OLSR), Ad-hoc On-demand Distance Vector (AODV), Dynamic
Source Routing (DSR) and Temporary Ordered Routing Algorithm (TORA). In addition, from a
transport layer’s perspective, it is necessary to consider Transmission Control Protocol (TCP) as
well for MANETs because of its wide application, which enjoys the advantage of reliable data
transmission in the Internet. However, the factors such as scalability and mobility cause TCP to
suffer from a number of severe performance problems in an ad-hoc environment. Hence, it is of
utmost importance to identify the most suitable and efficient TCP variants that can robustly
perform under these specific conditions. Therefore, this dissertation also makes an attempt to
evaluate the performance of the three TCP variants (Reno, New Reno and SACK) under a
variety of network conditions. The simulations results reveal that out of the three, the SACK
variant can adapt relatively well to the changing network sizes while the Reno performs most
robustly in different mobility scenarios. On the other hand, the research asserts the fact of
superiority of proactive protocol, over reactive and hybrid ones when routing the same traffic in
the network. Nonetheless, among the reactive protocols AODV performance (in the presence of
a high mobility) has been found to be remarkable.