Transmission
Control Protocol (TCP) is a reliable, end-to-end transport protocol, which is
most widely used for data services and is very efficient for wired networks.
However, experiments and research showed that TCP’s congestion control
algorithm performs very poorly over Wireless Ad Hoc Networks with degraded
throughputs and severe unfairness among flows.
This thesis studies fairness and throughput issues presented by TCP in Wireless
Ad Hoc Access Networks, which are Wireless Ad Hoc Networks with supporting
infrastructure, i.e. gateway, to send and receive packets from wired networks,
and concentrates on designing an applicable congestion control algorithm based
on the characteristics of the Wireless Ad Hoc Access Networks. We proposed
using DCCP (Datagram Congestion Control Protocol) with a specially designed
congestion control algorithm and implemented this congestion control algorithm
on NS2. Simulations were performed and the results
show the improvements on fairness and throughput achieved by using the designed
congestion control algorithm. The two flows with the new congestion control
tested in the simulation had Jain’s fairness index greater than 0.95 in
all combinations, where TCP flows may have a fairness index less than
0.6. The aggregate throughputs of the two flows with our new congestion
control algorithm also increased.