I. Introduction
Wireless sensor networks have brought a new revolution to information sensing [1] because of its advantages such as convenient deployment, strong anti-destructive ability and low cost, and have been widely applied in intelligent agriculture [2], environmental monitoring [3] and military monitoring [4], etc. It is a self-organizing network composed of low-power micro sensor nodes, which can perform wireless communication, data sensing, processing and storage for IoT applications. However, sensor nodes are usually powered by batteries with limited capacity [5] and deployed in harsh natural environments [6], which makes it difficult to charge, let alone replace batteries. Once the node dies because of energy exhaustion, it will bring irreparable disasters to the whole network such as incomplete monitoring data and great changes of network topology will lead to decision delay or error. Generally, network lifetime is reflected by the round of dead nodes and the most popular definitions are the rounds of the first dead node (FDN), half dead nodes (HDN) and last dead node (LDN) [7], [8]. Network energy consumption determines the death rate of nodes, and then affects the network lifetime. Therefore, it is of great significance to reduce the energy consumption of nodes and prolong the network lifetime.