Project Title

Wireless Cooperative Forwarding: A Novel MAC for High Link Reliability in Wireless Ad-hoc Network

Abstract

Unreliable link is a common problem in wireless networks. This problem is aggravated by the introduction of multi-rate capability of modern wireless device because ad-hoc routing protocols tend to select low-rate, long-distance links which are often unreliable for high-throughput communication. This paper presents a novel MAC mechanism to achieve high link reliability by utilizing inherent redundancy in wireless broadcasting. Cooperative Retry protocol is an extension of basic IEEE 802.11 MAC protocol. It appends an immediate retransmission procedure to the normal MAC atomic operation. By allowing local helper nodes, instead of the source to conduct retransmission, average link reliability could be improved with little overhead. Analysis shows that the new scheme improves the one-hop packet delivery reliability significantly while still maintaining throughput efficiency comparable to normal 802.11 MAC procedure. We also found that a network density of 8-10 neighbors is preferred to utilize the benefits of cooperative retry cost-effectively.

Publication

To be appear as a WINLAB Technical Report