Towards Analysis of Intra-flow Contention in Multi-hop Wireless Networks

Based on whether the competing active nodes are forwarding packets of the same flow, the channel access contention in multi-hop wireless networks can be classified into intra-flow contention and inter-flow contention. In this paper, we analyze the effect of intra-flow contention on multi-hop network performance. First, we demonstrate that intra-flow contention makes up a large proportion of contention in the network and may severely degrade the network performance. Then, to understand the performance improvement by eliminating intra-flow contention, we consider an ideal MAC based on 802.11 DCF where intra-flow contention is eliminated. We analyze the performance of the ideal MAC by proposing a three-dimensional Markov model. Furthermore, we present an approximate implementation of the ideal MAC based on simple modifications to 802.11 DCF. Finally, extensive simulations are performed and the results validate the proposed model and reveal the performance improvement by eliminating intra-flow contention.