Priority Based Power Saving Mode in WLAN

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.