Stochastic channel modeling for ad hoc wireless networks

Due to nodes mobility and environmental changes in mobile ad hoc networks, the ad hoc channel is time varying and subject to fading. As a consequence of these variations, the statistical characteristics of the received signal vary continuously, giving rise to a Doppler power spectral density (DPSD) which varies from one observation instant to the next. Therefore, the traditional models can no longer capture and track complex time variations in the propagation environment. These time variations compel us to introduce more advanced dynamical models in order to capture higher order dynamics of the ad hoc channel. Stochastic ad hoc channel models, in which the evolution of the dynamical channels is described by a stochastic state space representation, are derived. The parameters of the stochastic state space models are determined by approximating the band limited DPSD. Two approximating methods are considered. The first one is simple and the second one is the complex cepstrum method. Inphase and quadrature components of the proposed stochastic ad hoc channel models are derived. Numerical results show that link performance for ad hoc case is worse than cellular case, but the performance gap shrinks with increased mobility