Practical rate adaptation for IEEE 802.11 WLANs

Wireless Local Area Networks (WLANs) have become increasingly popular due to the recent availability of affordable devices providing multirate capabilities. However, because of the time-varying characteristics of a wireless channel, no single rate can be optimal under all scenarios, and the device needs to tune its transmission rate dynamically. Therefore, rate adaptation is a critical component of its performance. In addition, the IEEE 802.11 standard does not specify an algorithm for automatic rate selection; it is intentionally left open to the vendors. In this paper, we propose a Practical Rate Adaptation algorithm, which utilizes both statistics and RSSI of ACK to decide the transmission rate that maximizes the throughput. We implement our algorithm in commercial products and carry out extensive experiments for performance evaluation. The results demonstrate that using both statistics and RSSI of ACK greatly improves system throughput and responsiveness under various wireless environments.