Recently wireless sensor network is widely used for military purpose, medical service, business, ubiquitous environment and academic researches. IEEE 802.11 MAC protocol is not proper for this wireless sensor network due to the lack of energy conservation.
SMAC[1] which takes advantages of sensor network is proposed by Wei Ye, John Heidemann and Deborah Estrin. SMAC is a suitable MAC protocol which reduces power consumption in sensor network with techniques like periodic listen and sleep, message passing, and adaptive listening mechanism.
But some problems may occur during maintaining periodic listen and sleep mechanism. One of them is the synchronization problem of multiple schedules which has different listen and sleep period. SMAC has solved this problem by putting border node who adopts both different schedules.
However in that case, the border nodes consume more energy than the other nodes, so it could die more quickly. Consequently, each network cluster which adopts individual schedule cannot communicate together.
In this paper, we proposed the Scheduling Unifying Algorithm (SUA). It solve the problem by unifying the schedules with elimination of border nodes. We evaluate the algorithm with NS-2. The simulations results show that the SUA prolongs the life time of the border node i.e., the life time of network communication, up to 250% maximally.
