Asynchronous Power Management Protocols With Minimum Duty Cycle and Maximum Adaptiveness for Multihop Ad Hoc Networks

IEEE 802.11 is currently the de facto medium access control (MAC) standard for mobile ad hoc networks (MANETs). However, in a multihop MANET, 802.11 power management may completely fail if stations are out of synchronization. To fix this problem, several papers have proposed various cyclic quorum-based power management (CQPM) protocols, which, however, may also fail if stations have different schedule repetition intervals (SRIs). Hence, adaptive CQPM protocols, namely, adaptive quorum-based energy conserving (AQEC) and hyper quorum system (HQS), were proposed to overcome this drawback. However, the duty cycles of AQEC and HQS are far from optimal. In this paper, we propose the optimal fully adaptive and asynchronous (OFAA) power management protocol for a multihop MANET, which has the following attractive features: 1) By means of factor-hereditary quorum space, the OFAA protocol guarantees that two neighboring stations can discover each other in bounded time, regardless of their clock difference and individual SRIs; 2) given the length of SRI, the duty cycle of a station reaches the theoretical minimum; 3) the number of tunable SRIs of every station reaches the theoretical maximum; 4) the time complexity of OFAA neighbor maintenance is O(1) ; 5) a cross-layer SRI adjustment scheme is proposed such that a station can adaptively tune the values of SRI to maximize energy conservation according to flow timeliness requirements. Both theoretical analysis and simulation results demonstrate that the OFAA protocol is much more energy efficient than AQEC and HQS protocols.