Statistical-Physical Models of Urban Radio-Noise Environments - Part I: Foundations

Abstract

Theoretical foundations for an analytical model of urban radio-noise environments are presented at a level of generality broad enough to include the pertinent physical and statistical elements which critically influence the temporal and statistical character of such interference in radio receivers. The central roles of geometry, directionality (beam patterns), waveforms (from the interfering sources), motion (Doppler), source density and distribution, and secular variations of source parameters, as well as the radiation mechanism, are specifically developed. The basic statistical model (BSM) involves independent sources, in space (and in time), leading to Poisson radiation fields and a Poisson process X(t) in a typical receiver. This received process X(t) can be considered the sum of a Gauss process (by the central limit theorem) representing the cumulative effects of a large number of sources, none of which is very large vis-a-vis the rest, and a Poisson process produced by those few strong transients which when present dominate the background. The process X(t) is essentially stationary for periods comparable to the secular period of changes in traffic intensity and flow, which permits the construction of usefully large experimental ensembles from which to estimate the process statistics. A semiempirical, but more analytically tractable model similar to that introduced by Hall [6] for impulsive atmospheric noise but used here for independent sources is also constructed. This model is represented by X(t) = a(t) Z(t), where a,Z are independent processes, both zero mean, and Z is regarded as Gaussian.