Enhanced Westwood+ TCP for Wireless/Heterogeneous Networks

摘要

Westwood/Westwood+ TCP is well known by its effective AIAD (Additive Increase and Adaptive Decrease) bandwidth estimation algorithm. In this paper, we propose an enhanced Westwood+ scheme for wireless/heterogeneous networks with a high random bit error rate (BER), in which the sender is introduced with the following three characteristics: 1) to consider the impact of corruption strength in bandwidth estimation; 2) to reset new slow start threshold (ssthresh) and congestion window (cwnd) after receiving every special ACK with random bit error event's information; 3) to effectively avoid the unwanted timeouts which can be induced in conventional TCP in the case that the retransmitted packets are corrupted in wireless channel. Simulation results show that in the heterogeneous network with 1% fixed packet corruption rate as well as variational packet loss rate, the proposed scheme could achieve prominent improvements in goodput over Westwood+, NewReno and Reno TCP, respectively, in most cases.