1. Prediction of fading and link budget in land-satellite (LEO) communication
Tal Nir & Ziv Gitelman
Department of Communication Systems Engineering , Ben-Gurion University

2. ROADMAP INTRODUCTION MULTI-PARAMETRIC ALGORITHM SIMULATIONS
COMPARISON WITH OTER ALGORITHM
CONCLUSIONS

3. ROADMAP INTRODUCTION MULTI-PARAMETRIC ALGORITHM SIMULATIONS
COMPARISON WITH OTER ALGORITHM
CONCLUSIONS

4. Overview Satellites form an essential part of today’s technology:
Satellite TV or Direct Broadcasting (DBS) of radio and television;
Global Positioning System (GPS) and the new Galileo system;
Surveying and weather monitoring satellites.
First satellite launched into space: Sputnik (1957).
Today: over 800 active satellites.

5. Satellite Communication
When using a satellite for long distance communications, the satellite acts as a repeater.
An earth station transmits the signal up to the satellite (uplink), which in turn retransmits it to the receiving earth station (downlink).
Different frequencies are used for uplink/downlink.
Source: Cryptome [Cryptome.org]

6. Classification of Satellite Orbits
Circular or elliptical orbit
Circular with center at earth’s center
Elliptical with one focus at earth’s center
Orbit around earth in different planes
Equatorial orbit above earth’s equator
Polar orbit passes over both poles
Other orbits referred to as inclined orbits
Altitude of satellites
Geostationary orbit (GEO)
Medium earth orbit (MEO)
Low earth orbit (LEO)

7. MEO vs LEO Satellite Characteristics
Circular orbit range altitude
under 2000 km
5000 to 12,000 km
Orbit period
from 1.5 to 2 hours
6 hours
Diameter of coverage
about 8000 km
10,000 to 15,000 km
Round-trip signal propagation delay
less than 20 ms
less than 50 ms
Max. satellite visible time
up to 20 min
few hours
System must cope with large Doppler shifts

8. Geometry Terms
Elevation angle - the angle from the horizontal to the point on the center of the main beam of the antenna when the antenna is pointed directly at the satellite
Minimum elevation angle
Coverage angle - the measure of the portion of the earth's surface visible to the satellite

9. Satellite Link Performance Factors
Distance between earth station antenna and satellite antenna
For downlink, terrestrial distance between ground based station antenna and “aim point” of satellite
Buildings’ overlay profile and their random distribution above the rough terrain

10. Propagation Model Reflection Diffraction Scattering
Source: P M Shankar

11. Link Budget Average Path Loss, Lav, dB
Fading describes how the received signal amplitude changes with time.
To describe statistical characteristics of multipath phenomena different statistical distributions are usually used
Most complicated scenario with strong multipath fading can be sucsessfully described by Rayleigh PDF and CDF 11

12. Rayleigh Fading Distribution
Describes the received signal envelope distribution for channels, where all the components are non-LOS:
i.e. there is no-line-of–sight (NLOS) component.
It can arise when a two-dimensional vector has elements that are normally distributed, are uncorrelated, and have equal variance 12

13. ROADMAP INTRODUCTION MULTI-PARAMETRIC ALGORITHM SIMULATIONS
COMPARISON WITH OTER ALGORITHM
CONCLUSIONS

14. General problem
hmax=110
hmin=10
LEO
(/MEO)

15. Multi-Parametric ALGORITHM
Vertical plane :
CDF(z1,z2)

16. Multi-Parametric ALGORITHM
Horizontal plane :
Profile
Horizontal plane-
Distributions and density of buildings.
CDF(R) :

17. Multi-Parametric ALGORITHM
Vertical plane : CDF(z1,z2) =
Horizontal plane : CDF(R)=> p1:= Single scattering
p2:= Double scattering
p3:= Triple scattering
[ We consider worst case taken CDF of Rayleigh ]

18. ROADMAP INTRODUCTION MULTI-PARAMETRIC ALGORITHM SIMULATIONS
COMPARISON WITH OTER ALGORITHM
CONCLUSIONS

19. SIMULATIONS Simulation Setup: Simulator written in Mathematica
Simulations performed for city of Stockholm

20. Simulation Results

21. SIMULATIONS
Simulation Results : 1;

22. ROADMAP INTRODUCTION MULTI-PARAMETRIC ALGORITHM SIMULATIONS
COMPARISON WITH OTER ALGORITHM
CONCLUSIONS

23. Existing Algorithms Empirical – cannot be used for many scenarios
Statistical – do not exactly predict total Path Loss (Loo model, Lutz model)
Physical – Statistical - every time needs information about geometry of the local buildings (long time)
Multiparametric stohastic – currently used

24. ROADMAP INTRODUCTION MULTI-PARAMETRIC ALGORITHM SIMULATIONS
COMPARISON WITH OTER ALGORITHM
CONCLUSIONS

25. CONCLUSIONS
In practical meaning, the multi-parametric algorithm is a new tool to investigate a signal strength fading, based on propagation multipath phenomena, by using features of the built-up terrain and antennas location compared with building height profile

26. Thank you Any Questions ?

27. REFERENCES