Research And Improvement Of WSN Asynchronous MAC Protocol

Wireless sensor network is a key support technology of Internet of Things. Itputs micro sensor nodes with characteristics of low cost and energy consumption inthe area where people can monitor information. These nodes need to be possessedwith the function of detection, control and wireless transmission, and can construct amulti-hop and self-organized network through the method of sharing wirelessmedium. In practical application, sensors nodes are usually arranged in the placeswhere people are inconvenient to enter or reside for a long time, and the energywhich nodes can carry is limited. Therefore, energy saving is such a crucial issuefor wireless sensor network to solve.Communication, as the main part of energy consumption, is controlled by theMAC protocols of wireless sensor network. It plays an important supporting role inrouting, location, synchronization and control and other fields that wireless sensornetwork research relates to. By researching the existing MAC protocols of wirelesssensor network, an improved scheme based on asynchronous MAC protocols isproposed in this paper. Adaptive update AU-MAC protocol is presented, and throughbeacon avoidance send mechanism,early sleep principle, as well as approachingnode information table to achieve energy saving. Furthermore, principle of adaptiveupdate is introduced to maintain the correctness of approaching node informationtable. And its performance was verified through the NS-2network simulationsoftware.In addition, according to a widely used technology standard Zigbee for wirelesssensor network, using its underlying protocol IEEE802.15.4wireless standards andZigbee chip CC2430as the foundation, a hardware test node for wireless sensornetwork MAC protocol was designed in this dissertation. This paper would transplant operating system TinyOS designed for wireless sensor network in the testplatform. Exploiting the basic principle of TinyOS micro operating system and thearchitecture of IEEE802.15.4, the solution of IEEE802.15.4running on TinyOS wasdesigned. Using the physical layer service provided by IEEE802.15.4,running MACprotocol in the actual hardware nodes is achieved.At last, from NS-2software simulation results we can see, the AU-MACprotocols achieved better energy saving effect when the network traffic increased.Besides, this paper also completed the circuit design for MAC test node, transplantedTinyOS, and implemented IEEE802.15.4protocol, all of which laid a goodfoundation for further implementing AU-MAC protocols testing on the actual nodes.