Large area characterisation of urban UHF multipath propagation and its relevance to the performance bounds of mobile radio systems

A large number of small-area statistical channel descriptors in the form of average-power/time-delay profiles have been obtained in urban and suburban areas. The average excess delay and the delay spread are meaningful parameters which adequately describe the dispersiveness of the channel, and the variability of these parameters over a large area has been used as part of a two-stage model for characterisation of a UHF mobile radio channel. Suburban and urban areas exhibit quite different characteristics, reflecting the different nature of the environment. The variability of the statistical parameters is also a useful estimator of the performance bounds of radio systems. Using the measured data, together with relationships available in the literature for the performance of a given system in the presence of multipath, consideration is given to several system, such as DPSK data, SSB with pilot, FM voice and a phase ranging automatic vehicle location system. It is concluded that system techniques such as diversity reception can often lead to useful improvements in performance.