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上一期讲了移动通信的特点和分类,本期以汽车电话为主谈谈移动通信所涉及的主要技术问题。一、电波传播特性移动通信中的电波传播特性比之固定通信要复杂得多。这是因为通信的一方或双方是处于不停地移动中,而且在绝大多数场合,视距之内的通信,总会有建筑物、树木等等障碍物。因此,接收信号是由多个反射波合成的合成信号,每一瞬间,信号场强都有很大变化,甚至高达20dB 以上,故移动通信的信道是一个典型的参变信道。接收信号场强的变化和移动
On the last talked about the characteristics and classification of mobile communications, this issue to talk about the main mobile phone technology involved in the main technical issues. First, the radio wave propagation characteristics of mobile communications in the radio propagation characteristics than the fixed communication is much more complex. This is because one or both parties of the communication are constantly moving, and in the vast majority of cases, communications within line-of-sight always have obstacles such as buildings, trees and the like. Therefore, the received signal is a composite signal composed of a plurality of reflected waves. At each moment, the field strength of the signal varies greatly, even up to 20 dB or more. Therefore, the channel of the mobile communication is a typical parametric channel. Receive signal field strength changes and movement