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Annales Des Télécommunications

, Volume 57, Issue 9–10, pp 925–942 | Cite as

Adjacent satellite interference effects as applied to the outage performance of an earth- space system located in a heavy rain climatic region

  • Athanasios D. Panagopoulos
  • John D. Kanellopoulos
Article
  • 144 Downloads

Abstract

Interference effects are of utmost importance to the reliable design of modern satellite communication systems operating at Ku and Ka bands. In these frequencies rain attenuation is the dominant fading mechanism particularly for Earth-space systems located in subtropical and tropical regions. On the other hand, the main propagation effect on interference between two adjacent satellite systems is considered to be the differential rain attenuation. The subject of the paper is the development of a procedure for the prediction of carrier-to-noise plus interference ratio (cnir) statistics, under the presence of rain fading conditions, applied to heavy rain climatic regions. The method is based on a model of convective raincells and the gamma distribution assumption for point rainfall rate statistics, which fits better than lognormal distribution in subtropical and tropical regions. A tropical raindrop size distribution is also adopted for the calculation of the power-law parameters of specific rain attenuation. The numerical results are concentrated on the analytical examination of various operational parameters upon the CNIR statistics and the subsequent outage performance of the system. Comparison of the proposed model with an already existing one is attempted and the necessity of the present procedure for application to locations belonging to subtropical/tropical zones becomes obvious.

Key words

Satellite telecommunication Signal interference Tropical zone Rain Attenuation Outage Gamma distribution Probability calculus 

Nomenclature

ϕi

elevation angle of the slant path pointing toward satellite Si (i =1,2)

ε

differential angle between two satellites

Δψ

the differential azimuthal angle beween the projected slant paths

Ac

rain attenuation of the wanted signal referring to Earth-space slant path ES1

Ai

rain attenuation of the interfering signal referring to Earth-space slant path es2

A′c

rain attenuation concerning the projection of the slant path ES1

A′i

rain attenuation concerning the projection of the slant path es2

(CNR)nom

Carrier-to-noise ratio at the receiver input under nominal conditions

(CIR)nom

Carrier-to-interference ratio at the receiver input under nominal (clear-sky) conditions

(INR)nom

Interference-to-noise ratio at the receiver input under nominal (clear-sky) conditions

(cnir)

Carrier-to-noise plus interference ratio at the receiver input operating under rain fade conditions

r

non-exceedance level of the cnir (in dB)

f

frequency of the incident wave

Lc

effective average length of the Earth-satellite path ES1

Li

effective average length of the Earth-satellite path es2

Lcd

the projected Lc

Lid

the projected Li

a, b

Constants of the specific attenuation Ao (in decibels/kilometer)

H

effective rain height (0° isotherm height)

Ho

Average height above sea level of the Earth-station

vR βR

Gamma statistical parameters of the point rainfall rate distribution.

a

Characteristic parameter modeling the spatial inhomogeneity of the rainfall medium in Morita-Higutti model

Rm,Sr

Lognormal statistical parameters of the point rainfall rate distribution

G

Characteristic parameter modeling the spatial inhomogeneity of the rainfall medium in Lin’s model

ρo

Spatial correlation coefficient of specific attenuation Ao (dB/km) between two points of the rain medium

ρ

Correlation coefficient between the attenuations A′c and A′i

Prise en Compte du Brouillage par Satellite Adjacent Affectant un Système Terre-Espace Situé Dans une Région Climatique à Pluie Intense

Résumé

Les effets de brouillage ont une importance capitale dans la conception de systèmes fiables de télécommunication par satellite fonctionnant dans les bandes Ku (vers 12 GHz) ou Ka (vers 20 GHz). à ces fréquences, l’affaiblissement par la pluie est le mécanisme dominant d’évanouissement pour les systèmes Terre-espace situés dans les régions tropicales et subtropicales. D’autre part, on considère que le principal effet de la propagation sur le brouillage entre deux systèmes àsatellites adjacents est l’affaiblissement différentiel dû àla pluie. Le présent article a pour objet le développement d’une méthode de prédiction des propriétés statistiques du rapport signal àbruit plus brouillage (cnir), en présence d’évanouissements dus àla pluie, avec application en régions climatiques caractérisées par des pluies intenses. Cette méthode est fondée sur un modèle àcellules de pluie convectives et sur la modélisation statistique de l’intensité de pluie ponctuelle par une loi gamma, qui convient mieux aux régions tropicales et subtropicales que la loi log normale. Une distribution de la taille des gouttes tropicales est aussi adoptée pour calculer les paramètres de la loi en puissance qui représente l’affaiblissement linéique par la pluie. Les résultats numériques concernent principalement l’examen analytique de l’influence de divers paramètres opérationnels sur les propriétés statistiques du CNIR et des interruptions de transmission qui en découlent. Une comparaison du modèle proposé avec un modèle déjàexistant met en évidence la nécessité de la méthode proposée dans les zones tropicales et subtropicales.

Mots clés

Télécommunication par satellite Brouillage signal Zone tropicale Pluie Affaiblissement Interruption transmission Loi gamma Calcul probabilité 

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Athanasios D. Panagopoulos
    • 1
  • John D. Kanellopoulos
    • 1
  1. 1.Division of Electroscience — Department of Electrical and Computer EngineeringNational Technical University of AthensAthensGreece

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