This book focuses on the receiver design issue in high spectral efficiency communication systems, which is one of the main research directions in beyond 5G and 6G era. In particular, this book studies two technologies to improve the spectral efficiency, i.e., FTN signaling which transmits more data information in the same time period and NOMA scheme which supports more users with the same resource elements. Different commonly used channel propagation conditions are considered, and advanced signal processing algorithms have been developed for designing receivers, which is suitable for...