Detection of frequency modulated signals in Rayleigh fading channels based on time-frequency distributions

One of the applications with nonlinear nonstationary signals lies in mobile communications where nonlinear information bearing signals are faded by the time-varying propagation medium. Consequently, the envelope of the received signal is often modelled by a Rayleigh distribution. This Rayleigh fading severely degrades the performance of the mobile radio transmission system. Diversity reception is currently used to cope with this effect. This paper presents an alternative method based on time-frequency representation of FM signals affected by a Rayleigh stationary random process. Wigner-Ville analysis of different types of FM signals are presented followed by simulations and comparison with other second-order time-frequency methods of the Cohen’s class.