Optimal transmit power and energy level performance of random WSN in Rayleigh fading channel

In Wireless Sensor Networks (WSNs) where nodes are power-driven by batteries, it is important to extend the network lifetime by minimizing the energy consumption of each node. Excessive high transmit power consumes more energy and increases internode interference significantly, while low transmit power may cause network failure. Thus choice of optimal transmit power is one of the prime concern in such network. Optimal transmit power is the minimum power required to sustain the network connectivity while maintaining a predetermined maximum tolerable Bit Error Rate (BER). In this paper, optimal transmit power is derived for a WSN deployed based on a random topology. Further impact of Rayleigh fading on optimal transmit power, route BER and energy consumption for successful delivery of data in multihop using ARQ in each hop is studied for such random WSN. In random network, an intermediate node in the route selects the nearest node within a sector of angle (θ) towards the direction of the destination as the next hop. The effects of search angle (θ) on optimal transmit power, route BER performance and energy consumptions are also indicated.