Modeling and Characterization of Mobile-to-Mobile Communication Channels.


Geometrical propagation channel modeling has a pivotal role in designing most of the emerging wireless communication systems. Scattering is usually considered one of the major phenomena in affecting the propagation of radio signals. The effects of this phenomenon are more severe in mobile-to-mobile (M2M) communication environment because of the large number of scattering objects that reside around both mobile stations (MSs). In recent years, researchers have made significant efforts to model these effects either by their physical description or by their probabilistic trend. Geometrically based spatial scattering modeling is one such popular methodology used so far.

This dissertation focuses on modeling the 3D spatio-temporal channel characteristics for mobile-to-mobile(M2M) communication environment and presents mathematical expressions for their joint and marginal probability distributions. The proposed model is also analyzed for the characterization of Doppler spectrum.

The dissertation begins with the proposal of a 3D semi-ellipsoid geometrical channel model for M2M radio propagation environment assuming uniformly distributed scatterers around the mobile stations (MSs) within the defined regions. In order to model M2M communication environment realistically, a flexible geometry of the semi-ellipsoids is employed whose dimensions are made adjustable and rotatable about their vertical axes according to the directions of the MSs and the shapes of the streets and canyons where MSs reside. Using the proposed geometrical channel model, mathematical expressions for the joint and marginal probability distribution functions (PDFs) of angle-of-arrival (AoA) and time-of-arrival (ToA) in azimuth and elevation planes are derived. Mobility, being an important parameter in radio mobile channel modeling, is also analyzed through the characterization of Doppler spectrum of the proposed channel model. Furthermore, a generalized 3D geometrical channel model is also proposed for M2M communication environment. The generalized 3D spatial channel model consists of independently rotatable concentric semi-ellipsoids such that the inner semi-ellipsoids are scatter-free regions and uniformly distributed scatterers reside outside the inner and inside the outer semi-ellipsoids. By exploiting the proposed generalized 3D channel model, mathematical expressions for the joint and marginal PDFs of AoA and ToA in azimuth and elevation planes are derived. These spatial and temporal characteristics are analyzed for various channel parameters like elevation and orientation of each of the semi-ellipsoids.

The model is validated through its comparison with simulation results and measurement campaigns reported in the literature. Moreover, generalization of the model is confirmed by its comparisons with various existing geometrical models. It is shown that some notable geometrical channel models for F2M and M2M communication environments in the literature can be deduced from the proposed generalized model through the substitution of certain suitable values for a few channel parameters.

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