End-to-end wireless TCP with non-congestion packet loss detection and handling

Traditional TCP performance degrades over lossy links, as the TCP sender assumes that packet loss is caused by congestion in the network path and thus reduces the sending rate by cutting the congestion window multiplicatively, and a mechanism to overcome this limitation is investigated in this research. Our scheme identifies the network path condition to differentiate whether congestion happens or not, and responds differently. The basic idea of separating congestion and non-congestion caused losses is to compare the estimated current available bandwidth and the average available bandwidth. To minimize the effect of temporary fluctuation of measurements, we estimate the available bandwidth with a higher weight on stable measurements and a lower weight on unstable fluctuations. In our scheme, packet loss due to congestion invokes the TCP Newreno procedure. In cases of random loss that is not related to congestion, the multiplicative decrease of the sending rate is avoided to achieve higher throughput. In addition, each duplicate acknowledgement after a fast retransmission will increase the congestion window to fully recover its sending rate. Extensive simulation results show that our differentiation algorithm achieves high accuracy. Accordingly, the TCP connection over lossy link with the proposed scheme provides higher throughput than TCP Newreno.