On the Energy Savings of Adaptive Transmit Power for Wireless Sensor Networks Radio Transceivers

In this paper we present an adaptive transmit power optimization technique that is applied under varying channel to reduce the energy per successful transmitted bit. The output power is adaptively tuned to the best power level on link-by-link basis. Each node locally adapts the power according to the signal-to-noise ratio (SNR) variations (for all the neighbor nodes). The optimization is achieved under slow varying channel at the reception of a single packet. There exists an optimal point as the energy per bit reduces until a certain transmit power level and after that it starts increasing (as the signal power is too weak) due to retransmissions. These best points are identified under varying SNR conditions which provide some energy saving at the transmitter end. Different radio transceivers power profiles are used to show the gain over fixed transmit power. It is found that by dynamically adapting the transmit power on average can help to reduce the energy consumption by a factor of two.