A feedback-based scheme for improving TCP performance in ad hoc wireless networks

Ad hoc networks are completely wireless networks of mobile hosts, in which the topology rapidly changes due to the movement of mobile hosts. This freq uent topology change may lead to sudden packet losses and delays. Transport protocols like TCP, which have been designed for reliable fixed networks, misinterpret this packet loss as congestion and invoke congestion control, leading to unnecessary retransmissions and loss of throughput. To overcome this problem, a feedback scheme is proposed so that the source can distingu ish between a route failure and network congestion. When a route is disrupt ed, the source is sent a Route Failure Notification packet, allowing it to invalidate its timers and stop sending packets. When the route is reestabli shed, the source is informed through a Route Reestablishment Notification p acket, upon which it resumes packet transmissions. Simulation experiments s how that in the event of route failures, as the route reestablishment time increases, the use of feedback provides significant improvements in perform ance.