A Statistical Theory of Mobile-Radio Reception

In a typical mobile-radio situation one station is fixed in position while the other is moving, usually in such a way that the direct line between transmitter and receiver is obstructed by buildings. At ultrahigh frequencies and above, therefore, the mode of propagation of the electromagnetic energy from transmitter to receiver will be largely by way of scattering, either by reflection from the flat sides of buildings or by diffraction around such buildings or other man-made or natural obstacles. 1.1 The Model It therefore seems reasonable to suppose that at any point the received field is made up of a number of generally horizontally trav957 958 T H E BELL SYSTEM TECHNICAL JOURNAL, J U L Y ' - A U G U S T 19C8 eling free-space plane waves whose azimuthal angles of arrival occur at random for different positions of the receiver, and whose phases are completely random such that the phase is rectangularly distributed throughout 0 to 2tt. The phase and angle of arrival of each component wave will be assumed to be statistically independent. The probability density function which gives the probability p ( a ) d a t h a t a component plane wave will occur in the azimuthal sector from a to a + da will not be specified, since it will be different for different environments, and is also likely to vary from region to region within one environment; but the assumption that the phase