A non-stationary one-ring scattering model

This paper introduces a non-stationary one-ring scattering model in which the mobile station (MS) can move along a straight line from the ring´s center to the border of the ring. This movement results in a time-variant angle-of-arrival (AOA), which is modeled by a stochastic process. We derive the first-order density of the AOA process in closed form. Subsequently, a closed-form expression is provided for the local power spectral density (PSD) of the channel. We also formulate the local autocorrelation function (ACF) of the complex channel gain in integral form, from which a highly accurate closed-form approximation is derived. Furthermore, the average Doppler shift and the Doppler spread of the channel are computed. The analytical results are illustrated and physically explained. It is shown that non-stationarity in time contradicts the common isotropic scattering assumption. The merit of this study is to open a new window to the performance analysis of mobile communication systems under non-stationary channel conditions.