Design And Implementation Of Low Power Node In Wireless Sensor Networks

Wireless sensor networks consists of a large number of nodes deployed in a specific area, and it can be used to monitor or control the environment. The formation of network and data transfer are achieved through the cooperation betweens nodes. Wireless sensor networks can be widely used in military, medical, agriculture, etc., with high research and application value. Wireless sensor network nodes are small in size and can not be equipped with large capacity battery. And the large number of randomly distributed nodes deployed in inaccessible areas made energy efficiency a great challenge in wireless sensor networks. In the design of wireless sensor networks, energy constraint should be the priotity.This paper is supported by The National Key Technologies R&D Program of China: Wireless sensor networks based on IPv6network protocol development and validation, designing low-power wireless seneor network nodes for the project use.This paper first studies the hardware and software aspects of wireless sensor network architecture. In hardware, the role of each module and technological options are analyzed. In software, wireless sensor network protocol stack and main protocols used in the project are analyzed, and wireless sensor network operating system are analyzed and compared. Design principles and demand of nodes is proposed based on hardware module division. And based on hardware chips comparision and selection, a new low power wireless sensor network node hardware platform is designed and implemented, namely MSN-213. Then we design a low-power software on the MSN-213platform:combined with Contiki OS two-priority process scheduling mechanism, dynamic voltage scheduling mechanism on microprocessor module is designed and implemented.Energy is saved by dynamicly changing the microprocessor module operating status and frequency. And based on Contiki MAC, dynamic wake-up frequency adjustment mechanism is designed in RF modlue, so the MAC layer can dynamically adjust the wake-up frequency to adapt to the current network status. The mechanism is implemented in RF module AT86RF231.Finally, in a laboratory environment build a platform to test the actual node hardware. The test results show that the node this paper designed can perform network formation, IPv6address allocation and sensor data gathering and transmission. The node itself has low-power characteristic and with DVS in MCU module and dynamic wake-up frequency adjustment mechanism in RF module, node’s power consumption can be further reduced to1/5of its original value. The test results prove that the proposed node meets the design goals with great performance.