TITLE:
Schedule-Aware Power Management for Energy-Efficiency Improvement in 802.11u WLAN
AUTHORS:
Di Zhang, Qinghe Du, Pinyi Ren, Li Sun
KEYWORDS:
802.11u Standard; Power Saving; Transmission Schedule; Generic Advertisement Service (GAS)
JOURNAL NAME:
Communications and Network,
Vol.5 No.3C,
October
4,
2013
ABSTRACT: Mobile stations supporting the 802.11u standard can
access WLAN automatically when they are within the coverage of the network
service provided by this WLAN. To achieve this goal, the stations need to keep
“on” states includingidleandactiveall the time. However, studies have noted that the idleness of
stations often lead to considerable power consumption. Although the
conventional power saving mode (PSM) can provide energy saving effect to some
extent, its own disadvantage leads to lower energy efficiency when the number
of stations accessing the target WLAN. In this paper, we propose a
Schedule-Aware PSM (S-PSM), which can improve the energy efficiency in 802.11u
WLAN. Particularly, we use the Generic advertisement service (GAS) defined in
802.11u standard to broadcast the transmission schedule information and all
stations switch off their radios based on this information accordingly. We
introduce the Respond Contention Window to reduce the collision probability of
competition channel. When there is no packet in the access point (AP), AP
broadcasts the GAS frame and actives the Idle Timer. All stations will turn
into sleep and AP will not send GAS frame until Idle Timer expires. Simulations
have shown that our proposed scheme can significantly reduce power consumption
compared with the conventional PSM.