Impact of network coding on TCP performance in wireless mesh networks

Since it was originally proposed by Ahlswede et al. (2000), network coding (NC) has been the focus of many research efforts and proposals. In particular, NC has been put forward as a means to increase the capacity of wireless mesh networks, by exploiting the broadcast nature of wireless links. However, in spite of the fairly large number of papers on the subject of network coding, the impact of NC on TCP performance in wireless mesh networks is still not fully understood. By means of a thorough simulation study, this paper aims thus at providing insights about the interaction between TCP´s congestion control mechanisms and the underlying NC done by wireless relays. In particular, we focus on the influence of the main parameters related to the coding buffer used by such relays to encode packets. Our results suggest the feasibility of devising engineering rules for setting such parameters. Another main conclusion, in line with previous preliminary findings by the authors (Hassayoun et al., 2010) is that TCP performance can indeed be improved by the use of NC, but only as long as the wireless channel quality is above a certain level.