Evaluation of Optimal Transmit Power in Wireless Sensor Networks in Presence of Rayleigh Fading

Design of an energy efficient wireless sensor network (WSN) has emerged as an important research area. Minimizing energy consumption is the primary objective for WSN. WSN is usually characterized by tiny size, low cost and low transmission power. So optimization of transmission power is of great importance. Optimal transmit power not only achieves better network lifetime but also reduces inter-node interference significantly. In this paper we carry out simulation studies to investigate the effects of Rayleigh fading on the performance of WSN and optimal transmit power in presence of Rayleigh fading is derived. The effects of bit rate and Rayleigh fading on optimal transmit power are investigated under several network conditions. In this paper the network performance is estimated in terms of a quality of service (QoS) constraint given by the maximum tolerable bit error rate (BER). The derived optimal transmit power maintains a minimum BER constraint. The impact of fading on critical bit rate i.e., the bit rate below which a desired BER can not be achieved with any amount of transmit power is also studied.