在某些无线信道中，多普勒频移会引起无线信道输出信号的混叠的原因；无线信道中的多普勒谱有一种经典谱(classic spectrum)产生的机理；-In some wireless channel, the reason of Doppler frequency shift　causing aliasing　Doppler spectrum in the wireless channel, the mechanism of Generating a classical spectrum (classic spectrum)