In wireless ad hoc networks, IEEE 802.11 power management may completely fail if power-saving (PS for short) stations are out of synchronization. To.x this problem, [5]-[8] proposed various cyclic quorum-based power management (CQPM) protocols, which, however, may also completely fail if some PS stations have different schedule repetition intervals (SRIs). To conquer all these problems, we propose the OAPM protocol, which has the following attractive features. (i) By means of novel factor-hereditary quorum space techniques, OAPM ensures that two PS neighbors can discover each other in finite time regardless of their clock difference and their individual SRIs. (ii) Given the maximum value of SRI, Smax, the number of tunable SRIs for every PS station is Smax. (iii) The idle duty cycles for all SRIs are minimal. (iv) The time complexity of OAPM neighbor maintenance is constant. (v) A cross-layer SRI adjustment scheme is proposed such that a PS station can adaptively tune its SRI according to traf.c QoS requirements. Primary simulation results show that OAPM achieves better energy ef.ciency than existing CQPM protocols.
展开▼
