Study On The Characteristics Of The Rain Attenuation Of Ka-band Broadband Satellite Communication Channel

In a modern satellite communication system, the existing available spectrum resourcesare limited, ultra wideband high speed transmission must use higher frequency. The basic isthe use of Ku band broadband satellite communications services, so that Ku band applicationhas already very crowded, then the recent ultra wideband high speed transmission basic is aKa band satellite communication.In the first half of paper, the significance of Ka-band satellite communication systemsand the development of the status at home and abroad are introduced. The influence factors ofKa-band satellite communication channel are discussed. In Ka-band, the influence ofprecipitation on the signal and the attenuation are studied. Based on the mechanism of rainattenuation, the special attenuation by rain is calculated by the equivalent dielectricpermittivity model. According to ITU-R rain attenuation prediction model on the Earth-spacepath and the equivalent dielectric permittivity model, the curves of rain attenuation in Beijingand Guangzhou are simulated. We get the rain attenuation data in Changchun by Ku/Ka banddown link rainfall attenuation value transformation and the simulation results combined withrainfall characteristics. Then we use the ITU-R on rain attenuation and least square methodcurve fitting, to verify the effectiveness of its predictions.In the second part of the paper, according to the the characteristics of Ka-band satellitecommunications, the several attenuation factors influenced on Ka-band satellitecommunication channel, especially the impact of rain attenuation for satellite communicationchannel, are comprehensively analyzed. The multiplicative interference vectors of Ka-bandsatellite communication channel are determined, and the modeling of Ka-band satellitecommunication channel is completed. Based on the modeling, Ka-band satellitecommunication system simulation model is established. We analyze the affect of rainattenuation on ka-band satellite communication system, by different modulation modes. Thecomparisons of bit error rate (BER) in various circumstances are simulated. Bit error rate is the important parameter in the digital communication system. Then we analyze the simulationresults of the bit error rate when rain attenuation causes the Amplitude and phase fading of thesignal. According to the comparisons, we find OFDM as a multi-carrier modulation methodcan increase bandwidth utilization, and promote the The system performance much betterthan single carrier modulation method. And it has actual significance for the development ofthe satellite digital communications system.