Phase precoding with constant amplitude for slowly fading channels

The paper presents a novel phase precoding (pre-equalization) method for slowly fading channels, which achieves intersymbol interference (ISI) cancellation with only transmitted signal phase being precoded. The method improves the transmission performance without increasing the complexity of portable units. Theoretical analysis and computer simulation results demonstrate that, over frequency-selective Rayleigh fading and Rician fading channels, differential quadrature phase-shift-keying (QPSK) using the channel precoder has significantly lower bit error rates than those using a conventional decision-feedback equalizer (DFE), because the precoder achieves a higher efficiency of the transmitted signal power and is not subject to error propagation. The study is of interest to indoor radio communications