Cross Wigner Ville distribution of the wireless communication channel

Abstract

Almost all communication channels introduce dispersive or multiplicative disturbances which give rise to the dispersive effects known as time selective fading and frequency selective fading. Two parameters are used to characterize the dispersive and multiplicative channel. They are time delay spread and Doppler spread. Doppler spread gives a measure in frequency variation where it introduces time selective fading or flat fading. Time selective fading can be further classified as slow and fast fading. Frequency selective fading on the other hand is the effect of time delay spread in frequency domain where certain frequency components in the received signal spectrum have greater gains than the others. In this work, Doppler spread and time delay spread are estimated based on Cross Wigner Ville distribution (CWVD). It is derived from the Fourier transform of the cross bilinear product between the output and input of the system. Linear FM signal is adopted in the analysis where fading condition under Watterson channel model is considered.