A novel cross layer TCP pacing protocol for multi-hop wireless networks

Some research indicates that the TCP congestion control mechanism may cause the burstiness of traffic flow. A group of TCP segments are delivered simultaneously, while an acknowledgement (ACK) of a retransmission is successfully received. This burstiness leads to a network with high level contention , which extremely increases the probability of packet loss on wireless networks. TCP pacing is one of the solutions for TCP burstiness on multi-hop network. The idea is to spread the TCP segment transmissions over the whole Round Trip Time (RTT). Most of the pacing protocols attempt to insert a delay interval into the TCP segment flows or ACK flows, without noticing a Cross Layer pacing algorithm on IEEE802.11 with deferring and backoff mechanism. In this paper, we measure and analyze the way contention window size (CW) affects TCP throughput in different scenarios; and, we propose a cross layer TCP pacing protocol by controlling the lower bound of contention window for the optimization of the overall TCP throughput on multi-hop topology. Finally, a comparison of simulations is presented in order to verify the improvement achieved by our protocol.