Power and spectral efficiency of a family of constant-envelope root-of-unity filtered complex spreading sequences in WCDMA non-linear power amplification

This paper compares the spectral and power efficiency of a new multidimensional modulation strategy, employing a class of constant-envelope root-of-unity (CE-RU) filtered complex spreading sequences, with conventional Nyquist filtered QPSK modulated CDMA employing binary spreading sequences in nonlinear power amplification. The comparison is based on complementary cumulative probability density function peak-to-average power ratio (CCDF-PAPR) measurements, as well as the amount of spectral regrowth experienced when the power amplifier is driven close to the so-called 1 dB saturation point. Simulation as well as hardware results are presented to illustrate the superiority of the new complex-spreaded multi-dimensional WCDMA modulation schemes over conventional methods in terms of spectral and power efficiency in the presence of nonlinear power amplification.