Saving Energy by Adjusting Transmission Power in Wireless Sensor Networks

Wireless sensor networks (WSNs) have attracted a great deal of study due to the low cost of sensors and their wide range of applications. Most of the sensors used so far are point sensors which have disc-shaped sensing and communication areas. Energy-efficient communication is an important issue in WSNs because of the limited power resource and the inconvenience to recharge sensor batteries frequently. In this paper, we propose distributed algorithms to reduce communication energy consumption in WSNs by minimizing the total transmission power of sensors while maintaining the connectivity of the network. We first develop a distributed algorithm called DTRNG (Determine the Transmission power using RNG) based on RNG (Relative Neighborhood Graph) to let each sensor determine its transmission power. Then we point out that although RNG can maintain the connectivity of the network, it is not adequate to minimize the total transmission power of sensors. So we enhance it to algorithm DTCYC (Determine the Transmission power by removing the largest edge in CYCles). Mathematical proofs show that the result of the DTCYC algorithm is a minimal spanning tree, which can not only minimize the total sensor transmission power but maintain the connectivity of the network as well. Therefore, DTCYC algorithm is efficient in saving energy and can thus prolong the lifetime of WSNs.