Waveforms for fast fading channels

A technique is presented to design a binary digital transmission system for frequency flat fast fading channels. The author shows that it is possible to design good transmission systems for fast fading channels, with the aid of the Karhunen-Loeve expansion of the fading process, the optimum receiver is noncoherent, very simple, and no error floor exists due to fast fading. A simpler suboptimum detector can be considered which gives comparable results. Using a simple example, the author showed that the higher the fading rate, the lower the error probability (implicit time diversity), although this involves a higher receiver complexity and transmitted signal bandwidth