障碍物对无线信道影响的试验与研究

针对当前障碍物对无线传感器网络信道影响研究较少的现实，选取433 MHz 和2.4 GHz为载波频率，选择小车、铁网、墙体、铁门等为障碍物，以接收信号强度指数、平均丢包率、路径损耗为测试衡量指标，进行信道传播试验和数据分析，研究了不同障碍物对信道和通信质量的影响。在现有模型的基础上，提出以障碍物为分割点的分段数学模型。试验结果表明，随着通信距离的增加，信号强度会变弱、通信成功率会降低；障碍物空隙减小和厚度的增加，会加速信号的衰减和平均丢包率的增大。同时，以相同障碍物对不同载波频率路径损耗的影响得出，无线传感器网络工作频率越高，路径损耗越大，即在同等障碍物条件下载波频率越高，信号强度越低。利用最小二乘法对验证试验数据进行拟合，得出分段拟合方案的拟合系数R2在0.96 以上，说明采用分段数学模型具有更高的精度。

Experiment and study of obstruction on the radio channel

As less research exists on obstruction impact in wireless sensor network channel, signal propagation tests and data analysis are performed to investigate the obstacle impact to communication channel and communication quality using 433 MHz and 2.4 GHz as the carrier frequencies, using car, iron nets, walls, gates etc. as the obstacles, and using received signal strength index, the average lost packet rate, path loss as the test measures. A novel subsection mathematical model segmented by obstacles is proposed based on existing models. Experimental results shows that signal strength and communication successful rate decreases with the increase of communication distance, and that the shrink of obstacle sap or the increase of obstacle thickness speeds up signal attenuation and average package loss rate. Meanwhile, the path loss of different carrier frequency using the same obstacle arises along the increase of wireless sensor network operating frequency, that is to say, with the same obstruction; signal strength gets lower when carrier frequency gets higher. The proposed subsection mathematical model gains higher precision as the fitting coefficient R2 is above 0.96 when using least square as the experimental data fitting method.