Power management for VoIP over IEEE 802.11 WLAN

Power consumption is a critical issue for voice-over-IP (VoIP) over wireless LAN applications, especially when handheld 802.11 voice terminals are used as the end-user device. This paper provides an overview of power save procedures defined in the IEEE 802.11 wireless LAN standard, and proposes a novel power management technique for stations and services that use contention-based channel access, which we call unscheduled power save delivery (UPSD). We further investigate the performance of UPSD in combination with the eDCA mechanism defined in the 802.11e draft standard via an OPNET-based simulator. The results indicate that UPSD permits a lower duty cycle and delivers better VoIP capacity than legacy techniques.