Rate Adaptation with NAK-Aided Loss Differentiation in 802.11 Wireless Networks

The Physical Layer of the IEEE 802.11 standard family provides a set of different modulation and coding schemes and, thus, a multitude of data rates. However, the Standard itself does not specify a mechanism to select adaptively among these data rates to improve the network throughput. An efficient rate adaptation scheme should aim to improve channel utilization through selection of optimal data rates that suits current channel conditions. This paper proposes a rate adaptation technique that: 1) exploits the RSS of received DATA frame to recommend higher data rate for subsequent transmissions, 2) distinguishes causes of a frame loss by recording RSS of a CTS/ACK frame to predict if the channel quality is deteriorating or not, and 3) utilizes a NAK-frame to diagnose frame losses due to channel fading. Our scheme, dubbed as Differential Rate Adaptation with NAKAssisted Loss Differentiation (DRANLD), is simulated using ns-2 and shown to adapt well to rapidly fluctuating channels.