摘要
为探究土壤环境中无线地下传感器网络节点部署要求、信号传输及其应用环境的特性,分别以240、433和868 MHz为载波频率,研究了无线信道下地上至地下、地下至地上和地下至地下3种通信方式中无线射频信号的传播特性和节点埋藏深度、水平节点间距离以及土壤含水率等影响因素之间的关系,获得了接收信号强度、误码率等数据,并进行了统计分析。试验结果表明,节点埋藏深度和土壤含水率对AG-UG和UG-AG通信中RSSI和BER影响的24种模型拟合优度,R2最大为0.997,最小为0.910。水平节点间距离和土壤含水率对UG-UG通信中RSSI和BER影响的12种模型拟合优度,R2最大为0.971,最小为0.866。此外,建立了433 MHz频率下RSSI变化的三维曲面,可直观反映土壤环境下无线信号的传播特性,并采用SPSS软件对模型进行了验证。AG-UG和UG-AG通信中,拟合优度R2最小为0.954,最大为0.998,均方根误差RMSE在0.729～3.198 d Bm之间。UG-UG通信中,拟合优度R2最小为0.854,最大为0.960。均方根误差RMSE在3.238～6.553 d Bm之间。验证试验结果表明,该模型可以较好地预测不同条件通信中的接收信号强度,为土壤环境中无线地下传感器网络的部署和系统的建立提供了技术支持。
To explore wireless underground sensor network （WUSN） node deployment, signal transmission and the channel characteristics in the soil, the relationship among radio frequency signal propagation characteristics of AG - UG, UG - AG and UG - UG communication mode under wireless channel and node burial depth, horizontal inter-nodes distance and soil water content were studied with 240, 433 and 868 MHz carrier frequency for configuring wireless underground sensor networks in the soil. The experiment demonstrated that the maximum and minimum determination coefficient R2 of 24 models for goodness of fit were 0. 997 and 0.910, respectively, which was the effect of node burial depth and soil water content on RSSI and BER in AG - UG and UG - AG communication. And that maximum and minimum R2 of 12 models for goodness of fit were 0. 971 and 0. 866, respectively, which was the effect of horizontal inter-nodes distance and soil water content on RSSI and BER in UG - UG communication. Besides, three-dimensional surface of RSSI was built with frequency of 433 MHz, which could reflect the exact wireless signal propagation characteristics in the soil environment, and the model verification experiment was conducted through SPSS software. In the AG- UG and UG- AG communication, the minimum R2 of goodness of fit was 0. 954, the maximum was 0. 998, and root mean square error was in the range of 0. 729 -3. 198 dBm. In the UG- UG communication, the minimum R2 of goodness of fit was 0. 854, the maximum was 0. 960, and root mean square error was in the range of 3. 238 - 6. 553 dBm. Validation results showed that the model could better predict the received signal strength in different communications. The results can provide technical support for building of wireless underground sensor network system in the soil.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2015年第4期252-260,218,共10页
Transactions of the Chinese Society for Agricultural Machinery
基金
新世纪优秀人才支持计划资助项目(NECT-12-0473)
中国博士后科学基金资助项目(2014M552495)
关键词
土壤
无线传感器网络
试验
射频频率
信号衰减
Soil Wireless sensor netwrok Experiments RF frequency Signal attenuation
