【摘要】 以某机械加工车间为背景,对电波传播的路径损耗及小尺度衰落进行了测量和分析,通过有限时域差分法对电波极化偏转进行仿真,并设计了测量平台对仿真结果进行验证.结果表明,工业环境设备密集区域无线信号路径幅度衰减因子约为1.33,低于自由空间的传播情况,信号幅度在具有复杂形状的设备附近符合莱斯分布,在远离设备区域趋向方差极小的正态分布;金属设备引起电波极化方向的随机偏转,带来平均5.4 dB、最高13 dB的幅度衰减,同时降低了信道的交叉极化分辨率.可应用极化分集技术对抗信号随机衰落,提高工业无线传感器网络的性能鲁棒性.更多还原

【Abstract】 Measurements of radio propagation path loss and small scale fading were carried out in a machining workshop.Simulation of polarization rotation of electromagnetic waves was performed,which was also verified by a test platform.The results suggested that,in the industrial environment with dense metallic equipments,the propagation path loss factor was about 1.33,which was lower than that in free space.The signal envelopes conformed to the Rice probability distribution near the equipments with complex shapes,however,far from the equipments,they conformed to the normal distribution with very low variance.The huge random polarization rotation of electromagnetic waves,which was induced by the metallic equipments,maked the wireless signal attenuation with the mean level of 5.4 dB and the maximum level of 13 dB,meanwhile,decreased the cross polarization discrimination.Well designed polarization diversity schemes should be applied to fight the random fading and thereby enhanced the robustness of the wireless sensor networks.更多还原