Rain Attenuation Characteristics for Terrestrial and Satellite Links in the South Korea

Abstract

Attenuation induced due to rain is a prime concern in transmission of microwave signals. The revolution observed in communication technology has resulted in a pressing need for larger bandwidth, higher data rate and better spectrum availability. This has focused the research community to investigate higher electromagnetic spectrum space. The effect of rain attenuation is more pronounce when signals are being transmitted at higher frequencies. To optimize the use of microwave (3~30 GHz) and millimeter wave (30~300 GHz), the three tiers of communication system as such receiver, transmitter, and transmission medium must be properly designed and configured. However, the transmission medium becomes an issue at this range of frequencies. The significant factor that accounts for the degradation of the signal quality at this range of frequencies is resulted due to the effect of rainfall. Scattering and absorption by rain at microwave and millimeter bands is the prime concern for system designers. The International Telecommunication Union Radio wave propagation models (ITU-R.P) were used in the investigation of the propagation impairments. The study is divided into three parts. In the first part of this thesis, different rain rate computation methods will be presented. The experimental 1-minute rainfall amount data which are provided by Korea Meteorological Administration (KMA) of 93 different stations for a decade period from 2004 till 2013 are processed according to the prominent models and the suitable method is proposed. The analyses are primarily focus on nine major cities of the South Korea. The applicable rain rate contour plot at 0.01% of the time is developed using Kriging interpolation method through the advanced Geographic Information Systems (GIS) tools. Secondly, the study presents results of research into the interaction of rainfall with microwave propagation in 18, 38, and 75 GHz links in Icheon region of the South Korea. The study of rainfall characteristics allows for the estimation of rain induced attenuation in the presence of microwave and millimeter waves. The component of this work incorporate the study of rain drop size distribution and modeling of appropriate method for the estimation of rain attenuation in time percentage ranging from 1% to 0.001% of the time. In addition, the suitability of frequency and polarization scaling method as mentioned in ITU-R P. 530-16 are analyzed against the experimental database. Thirdly, study investigates the effect of propagation impairments such as rain on satellite communication link on earth-space path for frequencies of 12.25 and 20.73 GHz under circular polarization for Koreasat 6 and 19.8 GHz under vertical polarization for COMS1 (Communication, Ocean and Meteorological Satellite) in Mokdong station of the South Korea. The collection and analysis of meteorological data obtained for the period of 3 years from 2013 till 2015 as received from National Radio Research Agency (RRA) were performed to form statistics on diurnal, monthly and annual basis. The prominent propagation models applicable for slant path communication link were selected to calculate the attenuation distribution for a specified time percentage ranging from 1% to 0.001% of the time. The suitable technique is proposed which shows reliable estimation against the available local experimental database. Additionally, the regression coefficient used for the calculation of specific rain attenuation and the frequency scaling method as mentioned in ITU-R P. 618-12 are studied. Finally, the results are statistically analyzed through the several error matrices as well as from ITU-R P. 311-15 recommendations.