| 摘要: |
| 为解决苹果园中无线传感器网络的规划和部署问题, 研究2.4 GHz无线信道在苹果园中的传播特性。在山东省肥城市普通的苹果园进行实地试验。选取对信号传播影响最大的一列果树, 发射天线固定在两棵树之间发射信号, 分别测量6个高度18个位置点的接收信号强度和丢包率。回归分析结果表明:无论发射天线多高, 不同水平高度上的接收信号强度衰减均符合对数路径损耗模型, 拟合的决定系数为0.927~0.987。发射天线高度不变时, 衰减系数n值能用接收天线高度的二次函数曲线拟合, 拟合的决定系数为0.71~0.89;模型参数A和接收天线高度符合线性关系, 拟合的RMSE为0.2~1.2。建立以发射天线高度、接收天线高度和传播距离为参数的衰减模型并进行验证试验, 结果表明:RMSE为2~5, 94% 的R2值大于0.9, 预测模型能较好的估算收发天线高度不同时的信号强度损耗。 |
| 关键词: 无线网络 信号衰减 2.4 GHz无线信道 苹果园 |
| DOI：10.11841/j.issn.1007-4333.2014.06.25 |
| 投稿时间：2014-03-21 |
| 基金项目:国家"863"计划课题(2013AA102405) |
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| An attenuation model for 2.4 GHz wireless channel in apple orchards |
|
GUO Xiu-ming1,2, ZHOU Guo-min1, ZHAO Chun-jiang2, WANG Yan-an3
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| (1.Agricultural Information Institute of CAAS, Beijing 100081, China;2.National Engineering Research Center for Information Technology in Agriculture, Beijing 100097, China;3.College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China) |
| Abstract: |
| The wireless sensor network (WSN) nodes communicate with each other via wireless signals.The characteristics of 2.4 GHz wireless radio propagation in apple orchards was studied in this paper.Field tests were performed in a common apple orchard in Feicheng city in Shandong province.All the tests were performed along a line of trees, in which direction of the tree line had the most influence on radio propagation.The sender fixed between two chosen trees sent signals at a specific height, and the received signal strength and packet loss rate were measured at 18 points at 6 different heights.Regression analysis results showed that no matter what the sending antenna height hs was, the path loss of 2.4 GHz wireless channel followed a logarithm distance model at each height.The values of R2 were between 0.927 and 0.987.The attenuation index n could be fitted by a quadratic polynomial of the receiving antenna height hr at each hs, and the R2 values were between 0.71 and 0.89.The parameter A and hr had a linear relation at each hs, and the RMSE values were between 0.2 and 1.2.An attenuation model with parameters sending and receiving antenna heights and propagation distance was created.Verification results showed that 94 percent of the R2 were larger than 0.9, and the RMSE values were between 2 and 5.The new model could well estimate the signal loss with different combinations of sending and receiving antenna heights. |
| Key words: wireless networks signal attenuation 2.4 GHz wireless channel apple orchard |
