Real-time propagation forecasting for Earth-space communication

The use of frequencies in excess of 20 GHz for Earth-space communications is significantly impaired by the effects of the weather phenomena in the troposphere. The main contributing factor is attenuation due to rainfall but at higher frequencies (Q- and V-band 40/50 GHz) cloud attenuation can also be significant. Although small fades can be overcome by adapting the physical layer through changes to modulation, coding scheme and through power control, fades can be so deep that the link is lost. Knowledge of these conditions can help schedule and manage network resources and help reduce interference. This paper discusses the use of propagation models allied to numerical weather prediction and weather radar data to produce real-time and forecast prediction of fades. These can be used to both design and drive instantaneous fade-mitigation techniques.