Solving Ack inefficiencies in 802.11 networks

The founding idea behind this study was that 802.11 acks and TCP acks are substantial contributors to 802.11 over-heads, yet, they both provide the same functionality; reliability. Initial experiments suggest that 802.11 acks contribute to over 20% of the overhead in 802.11 networks. Unfortunately, without 802.11 acks, paths with RTTs greater than a millisecond are unable to utilise this additional performance because lost packets, which occur frequently in unacknowledged (NoAck) 802.11, are interpreted as congestion. This study experiments with a range of PEPs (Performance Enhancing Proxies) which retransmit lost packets. A new proxy, known as D-Proxy, designed to solve the shortcomings of previous I-TCP and Snoop proxies, is experimentally developed and tested in Linux. D-Proxy is a distributed, proactive proxy that caches, analyses and resends packets based on TCP sequence numbers. The results suggest that D-Proxy can substantially improve 802.11 throughputs.