Fast-responsive link adaptation for IEEE 802.11 WLANs

The mechanism to select one out of multiple available transmission rates at a given time is referred to as link adaptation. The effectiveness of a link adaptation scheme depends on how fast it can respond to the wireless channel variation. In this paper, we propose a truly-adaptive fast-responsive link adaptation scheme for IEEE 802.11 WLAN (wireless LAN). The key idea is to direct the transmitter station's rate-increasing attempts in a controlled manner such that the responsiveness of the link adaptation scheme can be guaranteed with minimum number of rate-increasing attempts. Since our scheme allows the transmitter station to make the link adaptation decision solely based on its local acknowledgment information, it does not require any change to the current 802.11 standard, thus facilitating its deployment with existing 802.11 devices. Our in-depth simulation shows that our scheme yields significantly higher throughput than other existing schemes including single-rate schemes, the ARF (auto rate fallback) scheme and its variants, in various fading channels.