Adapting TCP Exponential Backoff to Multihop Ad Hoc Networks

In a mobile ad hoc network, link failures and route changes occur frequently. Mistaking these events for congestion degrades TCP performance. Hence, TCP congestion control mechanisms should not react to such loss events. This paper deals with an enhancement of the congestion control mechanism, called TCP Adaptive RTO (TCP AR). This proposal relies on two basic concepts. First, it distinguishes routes failures from network congestion based on transport layer feedbacks. Second, during timeout, it adjusts the RTO's value to network conditions. We evaluate this new technique using different simulations scenarios, to compare its throughput gain, fairness and friendliness to those of TCP New Reno.