Chen, Jing (1993) Improved propagation loss prediction for land mobile radio communications. Masters thesis, Memorial University of Newfoundland.
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In land mobile radio communications, it is well known that almost 95% of the radio links between transmitter and receiver are non-line-of-sight. The propagation loss between transmitter and receiver is heavily dependent on the terrain features. Hence, this thesis examines and improves the CRC propagation loss prediction in two main aspects. -- One is to create a higher resolution and more accurate digital terrain data base based on the CRC data base. The developed procedure is as follows. For a given area of interest first the complete quadratic two-dimensional interpolation for elevations and the weighted vote method for surface codes are applied to augment the CRC data base from 500 meters spacing to 100 meters spacing. If the contour from the augmented data base is not checked with the topographic map, then the data of missed critical terrain features are taken directly from the topographic map and are used to correct the augmented data base. In this step, the triangular interpolation scheme is introduced to modify the elevations, and the weighted vote method is used to modify the surface codes. There are eight surface codes which indicate tree, bare ground, fresh water, suburban, marsh, seawater, urban core and unknown type. As the result of the modified data base, the evaluations of diffraction, reflection, tropospheric scattering, urban, and season losses are more accurate. Thus, the total propagation loss prediction is greatly improved. -- As another major work in this thesis, the modified diffraction loss prediction model is proposed. It involves: (a) for the implementation of the de Assis method, the radius of curvature of rounded obstacles' crest is determined by least-squares parabolic fitting; (b) the Deygout correction factor is first applied to deal with multiple rounded obstacles which are close to each other; (c) based on the availability of much more detailed information from the modified data base, all the defineable obstacles in a path profile are taken into account in the diffration loss prediction. -- It is shown that our propagation loss prediction results are close to CRC results when the terrain is smooth; but in the irregular terrain, our results provide a substantial improvement.
|Item Type:||Thesis (Masters)|
|Additional Information:||Bibliography: leaves 136-140.|
|Department(s):||Engineering and Applied Science, Faculty of|
|Library of Congress Subject Heading:||Mobile communication systems; Radio wave propagation|
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