In this paper, the behavior of small scale fading channel due to moving of a biological mobile sensor or moving of surrounding objects is presented. Specifically, the paper introduces the effects of multipath and scattering on the transmitted signal due to mobile biological sensors nodes within forest or open field filled of reflectors and scatters. The modeling of pass band transmitted signal fused in Rayleigh fading channel for both stationary and moving status of a receiver are derived. Finally, a complete MFSK-Rayleigh fading channel simulation is presented based on Matlab mfiles script, which comprises performance of MFSK signal over the channel.