On Throughput Limit of Multi-Rate IEEE 802.11 WLANs: Basic Access vs. RTS/CTS Access

Today´s IEEE 802.11 Wireless LANs (WLANs) usually support multiple transmission rates, where mobile stations adapt their data rates based on their link adaptation strategies. In this paper we analyze the throughput performance of multi-rate WLANs with link adaptation. Specifically, an analytical model is developed to derive the system throughput of both the basic access and RTS/CTS mechanisms. The proposed model is applicable to general multi-rate WLANs and independent of specific link adaptation strategies adopted. The accuracy of the model is validated by simulations in various network settings. Using the proposed model, we further derive the theoretical throughput limit of common multi-rate IEEE 802.11 WLANs. Interestingly, it is observed that for typical WLAN configurations, standard RTS/CTS mechanism performs closely to the throughput limit. Therefore, in multi-rate WLANs simply using standard RTS/CTS mechanism is preferred for its low complexity and close-to-optimal performance.