Is Dynamic Backoff Effective for Multi-Rate WLANs?

Dynamic backoff has been recently studied to improve the throughput of single-rate WLANs. In this letter, we investigate the effectiveness of dynamic backoff schemes in multi-rate WLANs. Specifically, an analytical model is developed to derive the throughput upper bound achievable by dynamic backoff schemes. Our results show that in multi-rate environments, dynamic backoff only achieves marginal throughput improvement compared with standard RTS/CTS mechanism under typical IEEE WLAN configurations. This observation, which is very different from that in single-rate WLANs, implies that it is preferred to simply use standard RTS/CTS mechanism in multi-rate WLANs for its low complexity and close-to-optimal performance.