Analyzing the Effective Throughput in Multi-Hop IEEE 802.11n Networks

In this paper we characterize the effective throughput for multi-hop paths in IEEE 802.11n based wireless mesh networks. We derive an analytical model capturing the effects of frame aggregation and block acknowledgements, features found in the new IEEE 802.11n standard. We describe the throughput at MAC layer as a function of bit error rate, aggregation level and path length. Using the results of our model as an upper bound, we show that current TCP implementations do not harness the bandwidth provided by the IEEE 802.11n MAC layer. Subsequently we introduce collision induced rate control which uses cross layer feedback to effectively estimate the available bandwidth based on our analytical model. We conduct a comprehensive performance study, showing that results from our analytical model are closely matched by simulation results. Furthermore we show that the proposed protocol achieves up to 50% more goodput and up to 70% less frame collisions compared to TCP-SACK and TCP-NewReno.