A TCP Enhancement for QoS-Aware Mobile Ad-HocNetworks

摘要

Successful deployment of Mobile Ad-hoc Networks (MANETs) is highly dependent on how their scarce resources are used by upper layer protocols. TCP plays a significant role in determining the workload of the network and its variants achieve different levels of performance as reported in literature. With the increase in delay-sensitive applications in today's networks, TCP experiences more spurious timeouts due to blocking by high priority traffic. The resulting retransmissions exacerbate the existing congestion problem in MANETs and misuse the available bandwidth. Our proposed TCP protocol (RE-TCP) achieves resource efficiency by adjusting the retransmission timer according to the medium contention, thus limiting the number of contention-induced retransmissions. In this paper, we first evaluate the impact of different loss recovery mechanisms on TCP performance in presence of voice traffic. We then analyze the resource efficiency of different TCP variants under contention-induced spurious timeouts. Our simulation study reveals a considerable improvement of TCP Reno by our proposed enhancement.