Abstract-This paper presents channel precoding schemes to combat intersymbol interference (ISI) over a frequency-selective slow fading channel in wireless communication systems using 4 shifted quadrature phase-shift keying or minimum shift keying. Based on the dimension partitioning technique, the precoders predistort the phase of the transmitted symbol in the forward link to combat ISI, keeping the transmitted symbol amplitude constant. The proposed schemes can ensure the stability of the precoder even in equalizing a nonminimum-phase channel, combat ISI without increasing the complexity of portable unit receivers, and reduce the envelope variations of transmitted signals such that power-efficient nonlinear amplifiers can be used for the precoded signals without causing a significant undue distortion. Theoretical analysis and simulation results are presented to demonstrate the effectiveness of the proposed channel precoding schemes.Index Terms-Channel precoding, equalization, intersymbol interference (ISI), minimum shift keying (MSK), 4 shifted quadrature phase-shift keying ( 4-QPSK), slow frequency-selective fading.