Improving the performance of multi-hop wireless networks using frame aggregation and broadcast for TCP ACKs

As data rates supported by the physical layer increase, PHY and especially MAC overheads increasingly dominate the throughput achievable by wireless networks. A promising approach for reducing these overheads is to aggregate a number of frames together into a single transmission. The 802.11n standard uses such an approach for unicast frames. We present the design of a system that can aggregate both unicast and broadcast frames. Further, the system can classify TCP ACK segments so that they can be aggregated with TCP data flowing in the opposite direction. A novel aspect of our work is that we implement and validate our design not through simulation, but rather using our wireless node prototype, Hydra, which supports a high performance PHY based on 802.11n. Our validation shows significant improvements in throughput for each kind of aggregation we support.