Delay-Intolerant Uplink Traffic Aware Timer-Based Power Management for Infrastructure IEEE 802.11 WLANs with Unreliable Wireless Links

摘要

Power management is indispensable for the battery-operated nodes to have a longer runtime. The existing Enhanced Timer-based Power Management (ETPM) overcame the shortcoming existing in the Basic Power Management (BPM) introduced in IEEE 802.11 standard. That is, when a node enters sleeping mode, its outgoing packets, referred to as the uplink traffic, are delayed until the current sleeping period expires, which may cause the BPM impractical in the delay-limited applications of 802.11 based Wireless Local Area Network (WLAN). The ETPM, however, also exhibits a drawback that Unreliable Wireless Link of WLAN is not considered, which is remedied by the power management scheme called ETPM-UWL presented in this paper. The statistics of the ETPM-UWL, including the average power consumption, the average delay, and the average number of the packets waiting for transmission are derived. In addition, the Optimization Problem (OP) for the ETPM-UWL is formulated that minimizes power consumption under delay constraint. With the OP, the ETPM-UWL enables a node to set its best maximum number of retransmissions (a parameter defined in the Medium Access Control (MAC) layer) and the values of the idle and doze timers embedded in the ETPM-UWL so as to achieve the optimal power consumption within a delay bound.