Rain Fade Calculation and Power Compensation for Ka-Band Spot Beam Satellite Communication in India

Abstract

The growing wireless and satellite communications market makes it more and more difficult to assign frequency resources in the commonly used C and Ku- frequency bands. Thus, frequency bands above 20 GHz i.e., the available Ka-band is of increasing interest for future satellite communication links. But propagation impairments impose a limitation on the use of the20/30-GHz frequency band for these applications. The attenuation due to rain can drastically reduce the received power level, requiring appropriate system design and fade countermeasures. This paper proposes a model of beam locations to implement TDM spot beams using steerable phased array antenna for Ka-band satellite communication over Indian sub-continent taking the statistical data of socio-economic market, geographical variation and rain rate distribution strategy. A comparison of attenuation levels using global crane, ITU-R and Moupfouma rain attenuation models in Indian region is simulated using daily collected data. The variation in instantaneous rain fall rate and corresponding attenuation data can be utilised to compensate power levels so that a reliable satellite link is available at user end for all time. It is found that a power variation of 20-30 dB occurs during 8-10 hrs in a year which need enhancement of power to attend minimum level for detection of signal with accuracy. The on-board data management, uplink and on-board downlink system power enhancement methodology can provide a useful receive signal service to rain affected spots by dynamically varying the allocation of power and bandwidth on-demand.