Performance of GMSK in nonlinear channel

The performance of GMSK in a nonlinear channel is considered. The GMSK signal is generated using a quadrature modulator and noncoherent reception is employed using a limiter discriminator with postdetection filtering. It is shown that errors introduced by the nonideal performance of the quadrature modulator will have a negligible effect on the BER performance if the channel is linear. However, when the imperfect modulator is cascaded with a nonlinearity, such as a class C RF power amplifier, the AM-PM distortion can seriously degrade the BER performance of the system.