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Basic Study on Radio Propagation Structure of Nountain Reelection in Digital Mobile Radio Communication

数字移动无线通信中常重选无线传播结构的基础研究

基本信息

批准号：
02452151
负责人：
IKEGAMI Fumio
金额：
$ 4.16万
依托单位：
Takushoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

In digital mobile radio, delayed multipath waves cause serious degradation in error rates. Reflection by mountains can produce very long delay which influences the system performance. However, there has been no way of predicting the strength of mountain reflection. Our study aimes to clarify the fundamental characteristics of mountain-reflected signals and how to predict the strength of the signals reflected by a mountain.Measurements of mountain-reflection have been made at 1.2GHz on the campus of Takushoku University, using directive antennas directed to a part of a mountain. The mountain-reflected signal was seperated by a sharp pulse inserted in a TV signal, and received pulse pattern was observed on CRT display and recorded and processed by a computer to give the receiver input signal level of the reflected signal component.In parallel, theoretical analysis was made to calculate the reflected signal strength taking a reflecting mountain as an absorbing scattering plane. The absorption factor at a mountain surface can be calculated from the measured reflected signal strength. According to the measurement, the wave attenuation due to absorption is obtained to be about 26.5dB in this case. In the measurements, the reflected signal strength was observed to vary with time. For example, the reflection increased by several dB in a few hours after snowfall, and also rapid fluctuation was eventually observed.As the results, a method of theoretical prediction of the mountain-reflected signal strength has been proposed for arbitrary propagation conditions, if the absorption attenuation of radio wave by the reflecting mountain surface is known. Further studies are necessary to prove the validity of the fundamental equation and the value of absorption factor for more generalized environments.

在数字移动的无线电中，延迟的多径波引起误码率的严重恶化。山脉反射会产生很长的延迟，影响系统性能。然而，没有办法预测山反射的强度。本研究的目的是阐明山体反射信号的基本特征以及如何预测山体反射信号的强度。在拓殖大学校园内，使用指向山体的定向天线，在1.2GHz处测量了山体反射信号。在电视信号中插入一个尖脉冲，将山反射信号分离，在CRT显示器上观察接收脉冲图形，由计算机记录和处理，给出反射信号分量的接收机输入信号电平，同时对以反射山为吸收散射面的反射信号强度进行了理论分析。在山表面的吸收因子可以从测量的反射信号强度计算。根据测量，在这种情况下，由于吸收而产生的波衰减约为26.5dB。在测量中，观察到反射信号强度随时间变化。例如，在降雪后的几个小时内，反射强度增加了几个dB，并最终出现了快速的波动。作为结果，在已知反射山体表面对电波的吸收衰减的情况下，提出了一种在任意传播条件下预测山体反射信号强度的理论方法。进一步的研究是必要的，以证明的基本方程的有效性和更广义的环境中的吸收因子的值。