A link adaptation scheme for improving voice quality and overall throughput over WLANs

IEEE 802.11 wireless local area networks (WLANs) support link adaptation technique (LA) which allows mobile nodes to select a proper transmission rate. Link adaptation algorithms use packet loss rate as an indication of poor channel conditions. However, most of existing link adaptation techniques cannot classify the loss as collision, congestion or channel error loss and they could mistakenly adjust the rate as if the loss was due to error prone channel. In this paper, we present a detailed classification of packet losses and propose our link adaptation scheme for delay-sensitive VoIP applications. Proposed algorithm only uses its local information and can be easily implemented without any changes on the current IEEE 802.11 standard. Simulation results show better perceived voice quality and higher overall throughput than other existing algorithms.