ETC系统信道传播损耗评估方法研究

Evaluation method for propagation loss of ETC system

无线信道传播效率是影响ETC系统性能的主要因素之一。考虑客车与轿车外形差异,定义了ETC系统信道传播损耗系数,提出一种基于两径模型的ETC系统信道传播损耗评估方法,便于评估ETC系统性能。评估方法预测及实测结果表明:ETC天线极化方式影响车载标签单元(OBU)接收功率,OBU距离地面高度越高,其接收功率越大;OBU识别范围小于10 m时,轿车引擎盖的电磁波反射引起垂直极化波衰减损耗突变,为保证OBU的成功识别,ETC天线距离地面高度应大于5.35 m。

The wireless channel transmission efficiency is one of the main factors affecting ETC Considering the shape difference between bus and car, channel transmission loss coefficient in fined, and a propagation loss evaluation method for ETC systems based on two-ray model was and measurement results indicate that ETC antenna polarization mode influences on the receiv system performance. ETC system was deproposed. Predicted ed power of on board unit （OBU）, the height OBU from ground more large, the received power more big. When the OBU recognition range is less than 10 m, because of the electromagnetic wave reflection of car hood, the vertical polarization wave attenuation loss is prone to sudden change. In order to ensure OBU is identified successfully in identified distance, the height ETC antenna from ground should be larger than 5.35 m.