Loss Differentiation Schemes for TCP over Wireless Networks

The use of loss differentiation schemes within the congestion control mechanism of TCP was proposed recently as a way of improving TCP performance over heterogeneous networks including wireless links affected by random loss. Such algorithms provide TCP with an estimate of the cause of packet losses. In this paper, we propose to use the Vegas loss differentiation algorithm to enhance the TCP NewReno error-recovery scheme, thus avoiding unnecessary rate reduction caused by packet losses induced by bit corruption on the wireless channel. We evaluate the performance of the so-enhanced TCP NewReno source (TCP NewReno-LP) with both extensive simulation and real test bed measurements, and we compare it with that achieved by existing solutions, namely TIBET [1], TCP Westwood [2] and the standard TCP NewReno. For that purpose, Linux implementations of TCP NewRenoLP, TIBET and TCP Westwood have been developed and compared with an implementation of NewReno. We show that TCP NewReno-LP achieves higher goodput over wireless networks, while guaranteeing fair share of network resources with classical TCP versions over wired links. Finally, by studying the TCP behavior with an ideal scheme having perfect knowledge of the cause of packet losses, we provide an upper bound to the performance of all possible schemes based on loss differentiation algorithms. The proposed TCP enhanced with Vegas loss differentiation algorithm well approaches