农业生态环境监测中无线传感节点信号有效传输距离的确定  

Determination of effective transmission distances of wireless sensor network nodes for agro-ecological environment monitoring

作　　者：徐兴元[1] 章玥[2] 季民河[1] 宋洋[2] 

机构地区：[1]华东师范大学地理信息科学教育部重点实验室,上海200241 [2]华东师范大学软件学院,上海200241

出　　处：《农业工程学报》2013年第14期164-170,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：华东师范大学地理信息科学教育部重点实验室主任基金(KLGIS2011B01)

摘　　要：农业生态环境的物理形态和结构复杂多样,对WSN(wireless sensor networks)的无线信号传输造成不同衰减影响。为确保无线传感器网络在农业环境中经济、合理、高效部署,有必要明确典型农业环境中无线传感节点间的有效传输距离。该文基于Shadowing信号衰减模型,利用当前通用的CC2530和CC2591无线通信模块,分别选定4种不同农业环境(湖泊、草地、农田、树林)开展单跳组网试验,通过设定不同距离测试传感器节点的接收信号强度指标(received signal strength indication,RSSI),分析不同环境中RSSI与传输距离间的变化特征。试验结果表明,所有测试环境获得的RSSI值与有效距离遵从Shadowing模型,其拟合度在0.9232～0.9846之间。通过对实测数据建立拟合模型,以接收节点的灵敏度为临界值,计算出湖泊、草地、农田、树林4种环境的理论传输距离分别为663.3,419.3,208.0和79.5m,而实测有效传输距离与理论值之间的相对误差在22%～34%之间。从误差分布看,复杂环境的实测值更接近理论值,而特殊结构的复杂环境似对实际信号传输有增强作用。该文的研究方法和模型估算获得的信号衰减系数可为实际环境监测组网提供有益参考。Wireless sensor networks （WSN） have been widely adopted for monitoring of agro-ecological environment, as they offer a number of advantages over traditional field observation methods. Signal transmission distances and qualities achieved by wireless sensors are highly related to the types of external environments. Attenuation of radio signals varies drastically for wireless sensor networks in different agro-ecological environments with diverse physical forms and structures. To achieve the economic, rational, and efficient goal for WSN deployment, it is essential to identify the effective transmission distance between wireless sensors in typical agro-ecological environments. This paper employed a long attenuation model, known as a Shadowing model, to examine the effect of distance on signal propagation loss with given transmitting power by measuring signal strength at the receiving node in one-hop networking experiments. The network was constructed using 12 nodes with commonly adopted CC2530 and CC2591 as wireless communication modules （both working at 2.4GHz ISM frequency band） and four different landscape settings as typical analysis environments （i.e. lake, grassland, low shrubs, and woodland）. To improve the signal sending and receiving capacity, wireless sensor nodes under experiment were equipped with a 5 dB short-stick antenna. The initial test was conducted to determine the minimum sensitivity of sensor nodes to be -97 dBm. By setting a series of distances between data sending and receiving sensor nodes, the corresponding received signal strength indication （RSSI） was recorded. A Matlab-based nonlinear regression model was built with the recorded RSSI data to analyze the relationship between RSSI and transmission distance for each of the four agro-ecological environments. The resulting coefficients of determination for the regression models indicated a strong relationship between RSSI and transmission distance, as they complied with the Shadowing model with a degree of fitting between 0.9232

关 键 词：农业 传感器 无线网络 有效传输距离 农业环境监测 

分 类 号：TP212.9[自动化与计算机技术—检测技术与自动化装置]