Unadvertised energy saving method for static and homogeneous wireless sensor networks

Several approaches have been proposed to increase the lifetime of a wireless sensor network (WSN) while preserving full coverage of the sensed area. Most of them employ protocols to reduce the energy consumption by switching the sensors off. To correctly decide the set of nodes to switch off without losing the full network coverage, these techniques must guarantee that all nodes have up-to-date information about their neighbours. Considering a static WSN, the only important information which must be regularly advertised is the energy level of the nodes. This information is exchanged between nodes in fixed time slots through one-hop messages. Nevertheless, the energy spent to transmit one simple bit of information is as the same used to process hundreds of transactions in a typical sensor. Thus, reducing the communication between nodes leads to an increase in the energy saving. This study proposes the unadvertised round energy saving (u-REST) algorithm which eliminates the energy level advertise messages, thus conserving a huge amount of energy. u-REST is able to increase the energy savings by deciding the set of nodes which can be switched off while preserving full area coverage without using energy level advertise messages. Mathematical proofs demonstrate that u-REST ensures a full coverage of the interest area while saving energy. In fact, it is mathematically demonstrated that the worst case for energy savings in u-REST is able to preserve more energy than the best case of all synchronisation-based methods.