Novel Delayed ACK Techniques for Improving TCP Performance in Multihop Wireless Networks

We study in this paper TCP performance over a static multihop network that uses IEEE 802.11 protocol for access. For such networks it has been shown in [6] that TCP performance is mainly determined by the hidden terminal effects (and not by drop probabilities at buffers) which limits the number of packets that can be transmitted simultaneously in the network. We propose new approaches for improving the performance based on thinning the ACK streams that competes over the same radio resources as the TCP packets. In particular, we propose a new delayed ACK scheme in which the delay coefficient varies with the sequence number of the TCP packet. Through simulations we show that the ACK thinning allows to increase TCP throughput substantially more than previous improvement methods.