A new method to include stochastic rough surface scattering into deterministic ray-optical wave propagation modelling is derived. It can be utilized in conjunction with the concept of ray launching. Similar to the Kirchhoff formulations, the approach is based on a tangential plane approximation, i.e. it is applicable to surfaces with gentle undulations, whose horizontal dimensions are large compared to the incident wavelength. However, in contrast to the Kirchhoff models, which are only valid for either slightly rough or very rough surfaces, the proposed stochastic scattering approach includes both the coherent and incoherent components at the same time. The purely deterministic ray-based modelling is expanded by a "stochastic" component, allowing for the first time to account for non-deterministic scattering in ray-optical wave propagation modelling.

A novel stochastic spatial propagation channel model for wide-band spread spectrum applications is presented. The model is set up for indoor scenarios, although in principle it can be extended easily to urban environments. Deterministic ray-tracing results are used to produce the huge data sets required for the statistical evaluation of the parameters of the proposed model. The approach for the stochastic model is based on physical wave-propagation, where the channel is described by multipath components including angles of arrival at the receiver and angles of transmission at the transmitter. In each modeling step, path properties change according to the movement of the radio stations (RSs). The appearance and disappearance of multipath components is modeled by a genetic process. Especially, changing delay times of the propagation paths yield a realistic Doppler behavior of the channel. A new approach to model the directions of multipath components in three dimensions has been developed. By relating the angles of arrival (or transmission) to the direct line between transmitter and receiver, a universal modeling approach, which is independent of the actual geometry, becomes possible. The novel stochastic spatial channel model allows the simulation of complex systems including arbitrary antenna configurations and patterns. A detailed description of the overall model is presented together with some initial simulation results.

A novel numerical algorithm based on the radiative transfer equation (RTE) is presented, which allows the calculation of the scattering and penetration of isolated vegetation specimens such as, e.g., single trees, bushes, etc., at mm-wave frequencies. For this purpose, the RTE is stated in a discrete form, and the vegetation structure is discretized in elementary volumes. A step-by-step solution is proposed to solve for the desired attenuation, and indications on the influence of the different parameters on the propagation characteristics are given. A qualitative justification to the approach is presented and finally, a comparison with scattering measurements of ficus trees at 75 GHz is shown.