Performance of a Cooperative Relay-Based Auto-Rate MAC Protocol for Wireless Ad Hoc Networks

Cooperative communication is becoming a promising technology for wireless networks by exploiting multipath fading instead of mitigating its impact. To integrate cooperative diversity into practical systems, efficient protocols are needed across the entire protocol stack. This paper presents a Cooperative Relay-Based Auto-Rate MAC protocol (CRBAR) to enhance the multi-rate capability along a long link. By leveraging the broadcast nature of the wireless medium and spatial diversity, a low-rate hop can be replaced by two high-rate hops via adaptive MAC-layer cooperation. To adapt to dynamical channel variation and network topology, the relay candidates adaptively select themselves as the relay nodes and determine the relay scheme and transmission rates based on the instantaneous channel measurements. System-level simulation study shows that CRBAR significantly outperforms traditional rate adaptation schemes in realistic scenarios.