Priority Based Power Saving Mode in WLAN

Abstract

According to employing power saving mode (PSM) scheme or not, stations (STAs) in wireless local area networks can be classified into two categories: STAs using PSM (PS- STAs) and STAs staying in active mode (AM-STAs). In IEEE 802.11 standard, a PS-STA periodically wakes up and retrieves data buffered at the Access Point through contending with both other PS-STAs and AM-STAs for its PS-Poll's transmission. Although AM-STAs usually have no concern with energy, their contention degrades the energy efficiency of PS-STAs, which usually have life concern, by 1) increasing the time duration for data retrieving and 2) increasing the number of PS-STAs which contend throughout the whole beacon interval but get no access opportunity. This paper first proposes a general priority based power saving mode (PBPSM) scheme which achieves PS-STAs' higher energy efficiency than PSM by assigning different channel access priorities. Then, we choose enhanced distributed channel access in IEEE 802.11e to implement the general mechanism and analyze PS-STAs' energy efficiency for both PSM and PBPSM. Numerical results show the effectiveness of our mechanism.