桃园中无线传感网络通信协议改进设计

Design and Improvement of the Communication Protocol for Wireless Sensor Networks in Peach Garden

为部署和运行符合桃园灌溉应用要求的无线传感网络，选取2470MHz载波频率，以长时间监测数据包传输率为基础获得可靠通信距离为40in，短时间内数据包传输率监测结果的分析表明无线链路在短时间内的变化很剧烈，且链路间没有明显的相关性。根据应用要求和链路特点设计了无线传感网络的通信协议；为降低监听功耗，对泛洪时间同步协议进行改进，设计了更符合本应用要求的泛洪一固定根节点时间同步协议；针对短时间内链路质量变化剧烈的特点，改进采集树路由协议以提高数据包传输效率，将两种协议结合，设计了较完备的通信协议，并在TinyOS无线传感网络操作系统上用nesC的编程方法进行实现，最后在桃园中进行现场实验，结果表明：全网节点时间同步的误差小于10ms，研究的通信协议与基于MuhihopLQI的通信协议相比，数据包传输率提高8％～15％，两节AA电池可供节点运行264d，具有很低的功耗。

With the aim to deploy wireless sensor networks and accommodate to application in a peach garden, the frequency of 2 470 MHz was selected, a distance of 40m was defined as a reliable communication distance based on the monitoring of variance of packet deliver rate in long term, the result and analysis of short term monitoring of packet delivery rate showed that quality of wireless links changed greatly in short term and there were no significant correlation between them. Then a communication protocol was designed based on the requirement of application and the characteristics of links：with the aim to reduce power consumption of listening , the flooding time synchronization protocol was improved and flooding-stable root time synchronization protocol was designed; as the link quality changes greatly in short time the collection tree protocol was improved to enhance the packet deliver efficiency, a comparatively complete communication protocol was designed by combining these two protocols above. After that the protocol was implemented with nesC language in TinyOS, finally field tests were carried out in the peach garden, the result shows that the time synchronization errors are less than 10 ms in the whole net, the packet delivery rate of communication protocol is 8% -15% higher than that of communication protocol based on MuhihopLQI. A TelosB node can run 264 d, with the supply power of two AA batteries, indicating that the communication protocol achieves very low power consumption.