Research On Communication Protocol In Wireless Sensor Network For Road Traffic Monitoring

With the rapid development of China's automotive industry and transportation as well as the popularity of vehicles and the rapid development of WSN (Wireless Sensor Network), higher requirements of vehicle performance test are put forward. This thesis aims to study and design the WSN system for the road traffic monitoring based on the GAINSJ development platform, which is the product by Ningbo Zhongke IC Design Center (NBICC).ZigBee(IEEE802.15.4-2006 standard) is a category in the IEEE 802 family, along with some of the well-known protocols such as Wi-Fi, Bluetooth. Unlike these protocols,ZigBee technology was developed for low-rate WPAN(LR-WPAN)which feature long battery life by having low date rates,low power consumption, self-healing ability for the network.The thesis researches the IEEE802.15.4/ZigBee protocol, discusses the realization of ZigBee protocol in network layer, ZigBee device type and network topology, analyzes the routing mechanism, then discuss the results of various cases simulated on OPNET. Steady case with single route, router failure leading to self-healing, stability in the presence of moving end devices, case of influence of propagation delay, and some limitations observed, due to an incomplete ZigBee library model.According to the ZigBee protocol and based on the GAINSJ development platform, we design the easy and feasible system for the road and traffic monitoring, and study the detailed implementation of protocol stack in network layer and application layer, complete the ZigBee network node communication and data receiving and sending. On a real site, by testing the speed of the car outdoors, we have measured the feasibility of the monitoring system, which has high application value. By testing the effective propagation path between the ZigBee nodes respectively in spacious and empty place and place with some obstruction, we analyze the ZigBee's transmission performance in practical application; indicate that the obstruction between the ZigBee nodes deeply influences the ZigBee's transmission performance and present method to this problem.Finally, it summarizes the investigation and indicates the prospect for further work.