Impact of Optimal Hop Distance on the Network Lifetime for Wireless Sensor Networks With QoS Requirements

In this letter, the impact of the optimal hop distance (OHD) on the network lifetime (NL) is analyzed in wireless sensor networks with the consideration of link quality of service (QoS) requirements. OHD is defined as the distance between the node and its next-hop's optimal relay position (ORP) to the destination node, where the ORP determines the performance of the energy-efficient relay. If OHD equals the characteristic distance (CD) of the path, the minimum-energy path for a given node pair can be achieved. Moreover, the link rate also influences the NL. Hence, considering an expected link outage probability, the minimum link rate, which is related to OHD, and its corresponding expected estimation of the average link transmit power of the node are calculated. Finally, an algorithm for joint energy-efficient relay selection and link-rate allocation based on OHD selection is proposed to extend the NL. Simulation results show that the NL can be extended when OHD is less than CD.