Enhanced statistics-based rate adaptation for 802.11 wireless networks

Rate adaptation is a common technique to exploit channel diversity in wireless networks. Despite the many rate adaptation algorithms proposed for 802.11 networks, statistics-based schemes remain the most widely adopted approaches in commercial 802.11 products due to their simplicity and practicality. However, statistics-based schemes suffer some disadvantages. Our previous research effort revealed the rate avalanche effect that could significantly degrade the network performance of heavily loaded 802.11 networks. In this work, we propose RADAR (Rate-Alert DynAmic Rts/cts exchange), a novel enhanced rate adaptation system that can effectively alleviate the impact of the rate avalanche effect. RADAR detects rate avalanche through maintaining a dynamic range-based mapping between rates and RSSI (received signal strength indicator) measurements. It judiciously exploits dynamic RTS/CTS exchanges to effectively suppress the rate avalanche effect while at the same time minimizes the transmission overhead of RTS/CTS exchanges. Being fully compatible with current 802.11 standards, RADAR can be readily implemented in the NIC driver. Through extensive simulations using realistic channel propagation and reception models, we demonstrate that RADAR is a practical and efficient performance enhancement approach for multi-rate 802.11 networks.

► The rate avalanche effect can degrade the performance of 802.11 WLANs.
► Dynamically tuning RTS/CTS can help to alleviate the rate avalanche effect.
► Our approach judiciously balances the benefit and overhead of RTS/CTS.