Abstract: In a wireless sensor network with limited energy, node sleep and data forwarding between nodes are a pair of contradictions. Wireless star network is both energy efcient and easy to control, but the network size is small. This paper presents an energy-efcient transfer method without a special router, the star network is extended into an internal and external two layer structure. So the control area increases to four times that of the star type. The following methods are used: 1) The topology control algorithm divides the network nodes into internal and external two layers with the center of the controller as the center. Inner layer nodes are used as routers by outer layer nodes. It simplifes routing and optimizes routing energy consumption. 2) Energy saving timing control. First, the nodes use the sequence of time segments from sleep to revival, reducing the listening time and the consumption of the current. Secondly, the short time monitoring of the inner node is coordinated with the transmission sequence of the outer node. It can not only realize the low energy communication in the normal state, but also solve the fast response in the emergency state. Test and simulation results show that the two level low power wireless network and its control method proposed in this paper are feasible, and its low power consumption and network delay characteristics meet the design requirements.

Key words: energy limited, routing energy consumption, topology control, wireless sensor network