Optimal Transmission Range for Minimum Energy Consumption in Wireless Sensor Networks

Energy efficiency is a hot topic in Wireless Sensor Networks (WSNs) because of the limited power supply. Routing strategies have a major impact on total energy consumption of network. Long-hop routing strategies demand substantial transmission power but are capable of reducing energy consumed by relay nodes. Short-hop routing strategies are just the reverse. This paper explores how multi-hop routing strategies are more energy efficient for periodic monitoring applications. We propose an energy efficiency metric for periodic monitoring applications, referred to as the Energy Distance Ratio per bit (EDRb). The concept of unreliable links is integrated into the proposed energy model to take transmission errors into account. By minimizing EDRb, an optimal hop distance is obtained for which related parameters such as optimal transmission power, optimal signal noise ratio (SNR) and optimal bit error rate (BER) are found in Rayleigh fading environment. On the basis of the obtained optimal hop distance, the low bound of mean EDRb for multi- hop path is computed. Finally, theoretical results are compared to simulations. It is shown that the network´s lifetime can be extended significantly by optimizing the hop length in a classical routing scheme.