Tuning Fast Link Adaptation Algorithms for CSMA/CA- and CSMA/E2CA-Based WLANs

The performance of fast link adaptation (FLA)algorithms in wireless local area networks (WLANs) is affected by the delay of the modulation and coding scheme (MCS) feedback information. In this paper, a novel FLA strategy is shown to be able to cope with expired MCS information. This strategy relies on a timeout-based mechanism that weights down the importance of the MCS feedback information as this becomes outdated. Moreover, the performance enhancement of using FLA in carrier sense multiple access with enhanced collision avoidance (CSMA/E2CA) protocol is also presented. Remarkably, CSMA/E2CA- based networks drastically reduce the number of collisions in comparison to the IEEE 802.11 standard mechanism, the carrier sense multiple access with collision avoidance (CSMA/CA) protocol. For completeness, the performance of FLA is compared with the ubiquitous auto rate fallback (ARF) algorithm, showing that FLA clearly outperforms open-loop techniques such as ARF.