Loss differentiation schemes for TCP over wireless networks

The use of loss differentiation schemes within the congestioncontrol mechanism of TCP was proposed recently as a way of improvingTCP performance over heterogeneous networks including wirelesslinks affected by random loss. Such algorithms provide TCP with an estimateof the cause of packet losses. In this paper, we propose to usethe Vegas loss differentiation algorithm to enhance the TCP NewRenoerror-recovery scheme, thus avoiding unnecessary rate reduction causedby 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 bedmeasurements, and we compare it with that achieved by existing solutions,namely TIBET [1], TCP Westwood [2] and the standard TCPNewReno. For that purpose, Linux implementations of TCP NewReno-LP, TIBET and TCP Westwood have been developed and compared withan implementation of NewReno.We show that TCP NewReno-LP achieves higher goodput over wirelessnetworks, while guaranteeing fair share of network resources withclassical TCP versions over wired links. Finally, by studying the TCP behavior with an ideal scheme having perfect knowledge of the causeof packet losses, we provide an upper bound to the performance of allpossible schemes based on loss differentiation algorithms. The proposed TCP enhanced with Vegas loss differentiation algorithm well approachesthis ideal bound.