The demand for high data rate reliable communications poses great challenges to the next generation wireless systems in highly dynamic mobile environments. In this Book, we focus on the blind receiver design for SISO transmission over block fading and time-variant channels. We investigate the joint Maximum-Likelihood (ML) channel estimation and data detection for SISO wireless systems with general constellations and propose a low complexity blind algorithm for finding the exact joint ML solution. The method uses some a priori information about the communication problem to improve the channel estimation accuracy and bit error rate. The Book considers two SISO systems; circular (OFDM) and linear convolution systems. In the circular convolution system, we show how an OFDM symbol, transmitted over block fading channel, can be blindly detected using the output symbols only. In the linear convolution system, we perform a blind equalization for a data packet transmitted over block fading channel using the received symbols only. Finally, the Book considers a more realistic problem in which we design a blind receiver for linear convolution SISO transmission over time-variant channels.