A distributed contention control mechanism for power saving in random-access ad-hoc wireless local area networks

The power consumption of mobile computers connected to wireless networks is negatively affected by the congestion level of the channel, and significantly depends on the medium access control (MAC) protocol policy. This paper illustrates the design and the performance evaluation of a new mechanism for the distributed contention control of the random accesses to the shared transmission channel of a wireless LAN (WLAN). The aim is the design of a distributed access scheme where each frame transmission leads to an optimal power consumption level, from the network interface (NI) viewpoint. To achieve this goal, we present a new analytical model to define the optimal average power consumption required by the NI for a frame transmission, and for a given random-access scheme. Specifically, we considered the Standard IEEE 802.11 Distributed Coordination Function (DCF) access scheme for WLANs. By exploiting the optimal values analytically derived, we define a parametric and adaptive power-save, distributed contention control (PS-DCC) mechanism. The proposed mechanism has been investigated via simulation. The power consumption of the proposed mechanism approximates the analytically defined optimal level, outperforming the Standard 802.11 DCF access scheme. To confirm the absence of overheads introduced, the channel utilization still results closely approximating the optimal values.