As the number of satellite networks increases, the radio spectrum is becoming more congested, prompting the need to explore higher frequencies. However, it is more difficult to operate at higher frequencies due to severe impairments caused by varying atmospheric conditions. Hence, radio channel forecasting is crucial for operators to adjust and maintain the link’s quality. This paper presents a practical approach for Q/V-band modeling for low Earth orbit satellite channels based on tools from machine learning and statistical modeling. The developed Q/V-band LEO satellite channel model is composed of; (i) forecasting method using model-based deep learning, intended for real-time operation of satellite terminals, and (ii) statistical channel simulator that generates a time-series path-loss random process, intended for system design and research. Both approaches capitalize on real-measurements obtained from Al-phaSat’s Q/V-band transmitter at different geographic latitudes. The results show that model-based deep learning can outperform simple statistical and deep learning methods by at least 50%. Moreover, the model is capable of incorporating varying rain and elevation angle profiles.

Sensing of the rain rate and the movement of the rain field over a relatively small geographical area may often be necessary for agricultural purposes, water management objectives or transport management in airports or harbors. In this paper, an entirely passive method is suggested to sense rainfall rate and extension of a rain field, with reconstruction in two dimensions using a tomographic method. In order to achieve this goal, multiple colocated satellite receivers are proposed to measure the beacon signal levels of geostationary satellites received at different azimuth angles. The tomographic reconstruction of the rain field takes the advantage of the dis-placement of the rain field due to the movement of air masses, while the rain intensity along the receiving path is estimated by the attenuation of the radio signal between the satellite and the ground receiver. To realize the proposed system, a complete receiver setup and an existing, operational group of satellites are selected. A widely known rain field modeling method is applied to generate test data and evaluate the system. The feasibility of a technically realizable system is provided, and its capabilities are compared with a hypothetical, ideal system. The methods and algorithms are tested on an existing geographical location, simulating a real operating environment.

To enable throughput rates in the terabit-per-second range, future satellite communications will have to utilize a large available bandwidth in the Q-band and above. At these high frequencies, the signal is severely degraded and attenuated by tropospheric phenomena, especially rainfall, which reduces the availability of satellite communication link and degrades the quality of service. Site diversity is an efficient technique used to mitigate the rain attenuation. In this paper, we evaluate the performance of the large-scale site diversity system consisting of ground stations in Ljubljana and Budapest based on long-term satellite signal measurement campaigns of Alphasat at 39.402 GHz. The measured attenuation time series are statistically analyzed and presented for a period of one year and compared with three representative prediction models.

Free Space Optics (FSO) and E-band links operating in parallel are investigated. In contrast to previous work in this field equal transmission rate of the two is assumed- 1 Gbit/sec in existing systems with a likely increase in the near future. Propagation characteristics are briefly presented. It is shown that practical difficulties preclude microwave backup to FSO links. Equal transmission rate leads to the possible application of parallel MIMO techniques. Outage capacity based on that is determined regarding for both binary and quaternary modulation and both Direct Detection (DD) and heterodyne techniques in the FSO link. The unexpected conclusion is that it is more the FSO link that serves as backup to the E-band link than the converse.