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The paper presents fast two-dimensional (2-D) diffraction modelling in the horizontal plane for site-specific propagation prediction in urban micro-cellular environments. Comparison with measurements and simulation of published results validate the 2-D modelling that significantly reduces the computation time and overcomes the limitation and difficulty of existing techniques for multiple building diffraction. The modelling makes three contributions which are 1) extension of an expression for multiple building forward diffraction and use of the extended formulation, 2) equivalent source technique for parallel-street multiple diffraction and 3) inclusion of reflections from curved surfaces of street building corners. Additional comparisons of three-dimensional model prediction with measurements for an urban line-of-sight environment place the work in a more complete context The results show that an increase in the number of rays may not enhance the accuracy of ray-tracing model prediction.

The new work makes three UTD (uniforn geometrical theory of diffraction) based path-loss prediction models and their experimental validations for urban micro-cellular mobile radio communications. The three models apply to the base station and mobile antennas much lower than the surrounding buildings and can be written in explicit forms for both vertical-and horizontal-polarization transmission and reception. Comparisons of their predictions with measurements at 900.5 and 1800 MHz in shadow zones of urban areas confirm the three models experimentally. The results demonstrate that fast two-dimensional (2-D) models which do not require a building height database can provide acceptable accuracy for micro-cellular mobile radio propagation predictions in urban environments. The methodology of this work is to deternine in advance significant rays to use, from a particular geometry of the buildings in an urban area. It appears suitable here for 2-D modeling for parallel-street problem and irregular side-street problems. It has the potential to be used in practical design of micro-cellular mobile radio systems.

Radiowave propagation measurements at 1.7 GHz for indoor mobile systems are described. A coherent pulse measurement is used to measure path loss and complex power delay profile of the radio channel. The results show that path loss and delay spread are highly dependent on building architecture and materials. By introducing special attenuation factors for penetrated walls and floors a statistical path loss model is obtained which gives relatively good results in office environments with small rooms. For large rooms and open areas a conventional model with distance dependence works best. Delay spread is modelled by having the volume of the indoor environment as a model parameter.