Characterization of Rain Fade in Jos, a Semi Temperate Region

Abstract

In a bid to meet the growing demands for mobile satellite applications, communication systems designers have been concerned about how rain attenuation affects satellite communication links especially in tropical region. This study has been conducted to characterize rain fade on satellite communication links in Jos (9.95650N, 8.85830E, 1,192 m), a semi-tropical region of Nigeria. The study will avail communication service providers with necessary information to improve the quality of service within the region. Rain data were retrieved from the Davis weather station for a period of one year in 2014. Rain attenuation data were obtained from a Ku-band beacon link set at a look-up angle of 56.50 on the European Telecommunication Satellite (EUTELSAT W4/W7) orbited on 036E. The different rain rates and their corresponding rain attenuation values were analyzed to obtain basic characteristics of rain fade in the region. The results showed that, as the rain increases in intensity, the measured attenuation increased, indicating that rain fade has direct relationship with rain rate. Also, the maximum level of rain fade for the year 2014 was 30dBm with a maximum rainfall intensity of 160mm/h. For most of the rainy months, the results showed that the logarithm-law, rather than the power-law, is more accurate for the modelling both rain rate and rain attenuation. This suggests that to model rain fade, a logarithm model may be more appropriate than a power law. The average threshold value of rain fade during rainy months was 11 dB; the minimum value was about 4 dB while the maximum was about 21 dB. The usual practice is for designers to provide fade margins based on the maximum rain fade threshold value of 21 dB. These fade levels require that communication system designers explore alternative measures of mitigating the fade levels of 21 dB.