Incorporating TCP Acknowledgements in MAC Layer in IEEE 802.11 Multihop Ad Hoc Networks

The poor performance of TCP in multihop ad hoc networks is mainly attributed to the inefficient interaction among different protocol layers in previous literature, while the heavy load caused by end-to-end TCP acknowledgements (ACKs) with limited information is usually ignored. In this paper, we propose a novel incorporating ACK transfer scheme, IACK, to alleviate its impact. In IACK, TCP acknowledgements are incorporated in the control packets at the MAC layer and are transferred hop by hop from the sink node to the source node. To meet the requirement of IACK, we enhance the packet queuing policy at the routing layer, and propose a new rate-based TCP transfer scheme, TCP-AP+. Then, we implement IACK in ns-2, evaluate it over comprehensive scenarios and compare it with TCP-AP and TCP-Newreno. Simulation results show that IACK improves both the TCP throughput and goodput significantly.