Ben-Gurion University of the Negev Department of communication systems engineering Effects of build-up terrain on radio signal fading in land-satellite communication links Supervisor: Prof. Natan Blaunstein Student: Ilya Liberman

Satellite Communication

Satellite applications Global positioning system (GPS) • Communications with ships at sea -Morse service ended last year for commercial vessels • Communications with land base stations Direct broadcast TV

Sattelite links

Mobile Radio Propagation Radio signals propagate according to three mechanisms – reflection – diffraction – scattering

Mobile Radio Propagation Result of the three mechanisms are three nearly independent phenomena: Path loss fading -Reduction in power density of an electromagnetic wave as it propogates throught space Fast fading (multipath fading) -Phenomenon that results in radio signals reaching the receiving antenna by two or more paths Slow Fading (Shadowing fading) -Occurs when a mobile moves behind an obstruction

Saunder’s physical statistical model Makes use of statistical distribution of physical parameters A mobile situated on a long straight street with direct ray from the satellite impinging on the mobile from arbitrary direction Street is lined on both sides with buildings whose height varies randomly No line of sight between sattelite and base station

Rayleigh build up distribution Rayleight comulative distribution function =Building height =Standard deviation of buildings height

General problem

Multi-parametric stochastic model Covers both LOS and NLOS states CDF=F(z,n)= CDF=Cumulative distribution function.Determines the probability of an event for wich z<h h1=minimum height of built-up layer h2=maximum height of built-up layer H(x)=Heaviside unit step function z=Building height n=terrain parameter

CDF as a function of building height and n parameter n high=> more low build-up terrain then high n small=> more high build-up terrain then low n=1=>building height uniformly distributed in the range h1 to h2

SIMULATIONS Simulation written in mathematica-tool Simulation performed for cities of Westminster and Guildford Westminster Guildford

Westminster city-simulation results Maximum building height: 90(m) Parameters: Minimum building height: close to zero Standard deviation : 17

Guildford city-simulation results Maximum building height: 20(m) Minimum building height: close to zero Standard deviation : 6

Conclusions Saunder’s physical statistical model gives precise results for high terrain only Multi-parametric stochastic model gives precise results for both low and high terrain

Thank you