ABSTRACT
This chapter deals with the description of the models used to characterize propagation phenomena in a mobile radio environment. It reviews some fundamentals of antenna theory, with the aim of obtaining the Friis free-space transmission formula. The chapter describes the stochastic behavior of the mobile radio signal by means of its statistical distributions. It investigates how the statistics of the received envelope will vary according to the proportion of direct waves to scattered waves. The propagation models can be divided into two groups, namely, theoretical models and empirical models. Mobile radio systems have been driven to use high radio frequencies due to the congestion at the low part of the frequency spectrum. The cells of the mobile radio systems are not clearly defined but have fuzzy boundaries because of the statistical fluctuation in radio path losses. The mobile radio propagation phenomena are very complex and cannot be entirely described by a single model.
