Worldwide techniques for predicting the multipath fading distribution on terrestrial LOS links: Background and results of tests

In 1988, the International Telecommunication Union (ITU) adopted new method s for predicting the deep-fading distribution due to multipath propagation for the average worst month on ultra high-frequency (UHF)-super highway fre quency (SHF) terrestrial line-of-sight CLOS) links. Employing refractivity gradient statistics available from world maps, the methods were recommended for application in all regions of the world. One method for the deep-fadin g range did not utilize detailed path profile information and was designed for preliminary planning or licensing purposes. A second method, which did employ the path profile was intended for more detailed design purposes, A m ultipath fading data base comprising some 246 links (including 34 over wate r) in 23 countries of the world has now been assembled for testing and revi sing these methods, Revisions to the geoclimatic model used in both methods and an associated method for predicting the shallow-fading distribution ha ve recently been adopted by Study Group 3 of the new radiocommunications se ctor of the ITU (ITU-R). This paper summarizes the basis of the original an d revised versions of the deep-fading prediction methods and presents the r esults of the most extensive tests to date. Some discussion of potential fu ture revisions is also provided.