Understanding the Responsiveness of Open Loop Rate Adaptation Algorithms of IEEE 802.11 WLAN

EEE 802.11 WLAN can adjust transmission rates according to channel environment. Among rate adaptation methods, open loop schemes do not rely on explicit messages that tell channel state of receivers but can estimate from the arrival of ACKs. However they cause rates to alternate repeatedly. To remedy such oscillation, Adaptive Auto Rate Fallback (AARF) and Robust Rate Adaptation Algorithm Plus (RRAA+) were proposed. This paper evaluates their performance by using simulations in order to understand their characteristics and responsiveness to channel conditions. We expect such efforts to encourage new ideas to improve them further. From the evaluations, we observed that AARF is superior to RRAA+ in the perspective of throughput. Also, we found that the oscillation does not badly affect performance as known and TCP and UDP traffic are influenced differently by rate adaptation.