Precoded nonlinear constant-envelope modulations

Nonlinear constant-envelope digital modulation schemes are attractive in applications where high power efficiency is required. When used in high-rate, band-restricted applications, intersymbol interference (ISI) results and must be compensated to obtain satisfactory error performance. Tomlinson-Harashima precoding has proven attractive in applications with linear modulations such as that in the V.34 standard for high-rate wireline modems. This paper presents results on new techniques for precoding and their performance analysis in additive noise and fading channels. Substantial performance improvement is obtained over systems without precoding and systems with the Tomlinson type of precoding.