CDMR: Cooperative diversity-based multi-copy relaying in mesh networks

The standard way to handle frequent transmission errors over wireless links is to use a link-layer automatic retransmission mechanisms. However, multiple retransmissions per link along an n-hop path leads to significant channel usage inefficiency and poor end-to-end performance. We propose a novel cooperative diversity based multi-copy relaying (CDMR) scheme for wireless mesh networks. CDMR improves system performance by effectively utilizing available network resources, allowing neighboring (helper) nodes along a selected route to cooperatively deliver (as opposed to using retranmissions) packets to the final destination. CDMR operates in two phases: helper establishment and cooperatively delivery. The fundamental challenges are to identify effective helpers and to synchronize helper transmissions in order to avoid collisions. CDMR provides a simple and effective solution with low overhead. Simulation results show that (even with just one helper node), CDMR is able to reduce retransmissions and improve end-to-end delay by 39% to 86% depending on the path length.