We present experimental results on the relationship between rain attenuation and simultaneous scintillation during rain events, based on beacon signal measurements at 19.7 (Ka-band) and 39.4 GHz (Q-band) from the geosynchronous Alphasat satellite (25 degrees E), received at two Italian ground stations, Spino d'Adda (42.1 degrees slant path) and Tito Scalo (35.5 degrees slant path). Time series data collected between 2015 and 2023 were processed at 16 Hz and filtered to isolate rain attenuation and scintillation components using fixed low-pass (0.05 Hz) and a band-pass (0.175-3 Hz) filters, respectively. The average rain attenuation (dB) and the average scintillation standard deviation (dB), computed in 1-min intervals, were found to follow a power-law relationship of the form and , consistent with a thin turbulent layer. The models were fitted to the data over the attenuation range = 1.0-15.0 dB, where system noise has minimal influence, and their performance evaluated using mean squared error. The modified thin-layer model showed the best agreement overall, with lowest MSE values found when fitting the model to the Tito Scalo Ka-band and Spino d'Adda Ka- and Q-band data. Additionally, to demonstrate the thin-layer model's effectiveness, the models are examined briefly when frequency scaling the behavior of scintillations from 19.7 to 39.4 GHz. Among the models tested, the modified thin-layer model provided the best match to observed measurements when scaling. These results indicate that thin-layer turbulence models provide a physically consistent framework for characterizing rain-conditioned scintillation during rain events.

ABSTRACT The growing demand for broadband satellite connectivity is accelerating the transition toward extremely high frequency (EHF) spectrum, particularly the Q/V‐band (40–50 GHz), which provides substantially larger bandwidth resources compared with conventional Ka‐band allocations and supports the deployment of next‐generation high‐throughput satellite (HTS) systems. Despite these advantages, Q/V‐band links are vulnerable to atmospheric impairments, with rain attenuation representing a primary source of signal degradation and link outages. Ensuring service continuity in this context requires accurate channel state prediction to enable proactive fade mitigation techniques (FMT), such as smart gateway diversity (SGD), which leverages geographically distributed gateways and dynamic resource management to counteract weather‐induced fading. This work investigates artificial intelligence–based channel prediction strategies to enhance SGD performance, using experimental data collected during the Alphasat TDP#5 Q/V‐band campaign. A medium‐term forecasting model based on a long short‐term memory (LSTM) neural network is developed to estimate the future probability of link outage. From a scientific research perspective, the adoption of the link outage probability itself as a driving metric for the SGD decision process represents an innovative aspect of this work, enabling a predictive and reliability‐oriented gateway management strategy. The model is trained and validated on real measurements acquired from the Aldo Paraboni experimental payload. Comparative results demonstrate that the proposed LSTM approach demonstrates improved performance over persistence‐based (Naïve) and linear prediction models, substantially reducing forecasting errors and enabling timely, seamless gateway handovers. These findings confirm the effectiveness of machine learning (ML) techniques in improving the reliability and resilience of next‐generation EHF satellite networks.

The Alphasat Aldo Paraboni experiment by the Italian Space Agency measures signal attenuation at 19.701 GHz and 39.402 GHz using beacon signals from a geosynchronous satellite to ground stations in Tito Scalo and Spino d”Adda, Italy. Second order statistics on data collected from 2015 to 2023 are presented, supporting the understanding that higher frequencies, as seen with the 39.4 GHz beacon, are more susceptible to atmospheric fading, exhibiting higher fade percentages, steeper fade slopes, and more frequent long-duration fades. Comparisons of the measurements statistics with Rec. ITU-R P.1623-1 models show expected discrepancies, with the ITU-R models underestimating fade percentages and counts while overestimating fade slope probabilities. These findings emphasize the importance of experimental campaigns and the opportunity to further refine predictive models.

Summary In 2008, the Italian Space Agency (ASI) consolidated its position on research and experiments regarding extremely high frequency (EHF) satellite communication through the proposal to the European Space Agency (ESA) of hosting a Q/V‐band experimental payload on board the Alphasat geostationary satellite. The latter large platform, launched in 2013, thus hosted the so‐called TDP#5 (Technology Demonstration Payload), aimed at performing the first Q/V‐band telecommunication and propagation experimental campaigns. Thanks to the precious contribution given to the definition of the overall mission and the scientific objectives, the payload was then renamed in memory of Professor Aldo Paraboni, pioneer of scientific research on EHF satellite propagation. Since 2014, a large number of satellite communication scientific experiments have been conducted by the University of Rome Tor Vergata, principal investigator for the ASI telecommunication campaign. Due to the excellent scientific results and the high reliability of the system, the experimental campaign is still ongoing. The main objective of the proposed telecommunication experiments is to demonstrate the feasibility of broadband satellite communications in Q/V band, optimizing and assessing, over‐the‐air, the performance of the indispensable adaptive transmission techniques. Moreover, the application of innovative paradigms related to software‐defined networking (SDN) and network functions virtualization (NFV) has been investigated in the framework of satellite systems exploiting beyond Ka‐band frequencies. The goal that drives this experimental activity is to provide to the academic community, manufacturers, and service providers useful tools to cope with Q/V‐band links for future satellite communication systems. The use of EHF links contributes to the reduction of RF front end and thus minimization of orbital junk; moreover, high throughput links in conjunction with software‐driven architectures enable a high level of system reconfigurability that is one of the pillars for a sustainable use of space. The paper presents the main results of the last 10 years of Q/V‐band experiments, as well as the plans and perspectives for future scientific and operational activities in a sustainable space framework.

Beacon power levels measured in 2015 in the framework of the Alphasat Aldo Paraboni propagation experiment at the two receiving stations in Tito Scalo and Spino d’Adda, for beacon frequencies of 19.7 GHz and 39.4 GHz, are calibrated to extract total attenuation timeseries. These timeseries are then used to perform an analysis on scintillations during rain events. The analysis shows that there is some deviation (23% and 38% at Ka band and Q band, respectively) in the slope of the power law fitted to the data, with respect to the slope of the power law provided in the thin layer model. Furthermore, it was found that the scintillation intensity ratio at Spino d’Adda and Tito Scalo are 22.2% and 21.1% smaller, respectively, than the theoretical one.

In the framework of the Horizon 2020 project QVLIFT, funded by the European Commission, a V-band high power amplifier based on gallium nitride (GaN) monolithic microwave integrated circuits (MMIC) technology was designed and developed. Design manufacturing and on-wafer pulsed measurements of two runs of MMIC fabrication were performed and the best chipsets demonstrated peak output power of about 5 W in pulsed mode. Waveguide modules were integrated and tested and are able to provide up to 2 W at 48 GHz in continuous wave.

High Throughput Satellite systems are expected to reach the milestone of terabit/s capacity in few years through the exploitation of Extremely High Frequencies (EHF), in particular Q/V-bands and W-band, in the feeder link. In this respect, the H2020 QV-LIFT project, kicked-off in November 2016, aims at filling crucial gaps in the ground segment technology required by future Q/V-band HTS systems. One of the most challenging objectives of QV-LIFT team is develop and test a smart gateway management system (SGMS) operating in the Q/V- band. The SGMS will implement fade mitigation techniques able to counteract the detrimental propagation impairments across the feeder link. This paper reports the optimization and simulation activities that have been performed to design SMGS control logic, with a focus on the atmospheric channel predictor and switching decision algorithm. The channel is fully characterized by synthetic time series of rain attenuation generated by a Multi-site Time-series Synthesizer (MTS).

This paper provides an overview of the space segment of the Aldo Paraboni mission on the Alphasat satellite and the technology programme that has developed one of the most powerful geostationary satellites in Europe. The Aldo Paraboni technology demonstration payload, funded by ASI under European Space Agency's Advanced Research in Telecommunications System Programme, was embarked as a hosted payload on the Alphasat satellite, launched on 25 July 2013. The Aldo Paraboni payload is composed of two main elements, an experimental communication payload operating at Q/V bands (COMEX) and a scientific payload formed by 2 beacons at Ka and Q bands (SCIEX). The Aldo Paraboni payload is a key technology element of the Aldo Paraboni Mission, which covers two main objectives: the communication segment of the mission aims at assessing the performance of satellite communication links at Q/V bands and investigating use Fade Mitigation Techniques (FMT, eg, Adaptive Coding and Modulation defined in DVB-S2 standard), while the scientific segment aims at characterizing in time, space, and frequency the K and Q band radio channel over Europe to permit development and improvement of propagation channels for slant paths.

Since the 1970s, satellite communications have been continuously evolving and improving to provide services characterized by increasing complexity and quality. This evolution has been supported by the constant increase in the operating frequency for achieving the necessary high data rates. This contribution focuses on the long-term key role of the Italian Space Agency in supporting research activities on (and the developments of) high-frequency satellite communication systems. The Alphasat experiment is the most recent effort of the Italian Space Agency, in collaboration with the European Space Agency, to thoroughly investigate the severe detrimental atmospheric effects impairing radio waves at high frequency (specifically, Ka and Q bands) and the associated fade mitigation techniques (eg, uplink power control, site diversity, and adaptive coding and modulation) required to achieve the typical target quality and availability of modern satellite communication systems.

SummaryIn the framework of the ASI Q/V band program, the “Aldo Paraboni” Payload embarked on Alphasat is devoted to the exploitation and the investigation on communications at the Q/V frequency band. The operation of this experimental payload allowed to demonstrate the potential of advanced broadband satellite communications at the Q/V frequency bands and represents an important step toward the development of future High Throughput Satellite (HTS) systems. The Italian Mission Segment (IMS) represents the ground infrastructure which allows to perform communications experiments (propagation impairment mitigation techniques (PIMT)) at 40/50 GHz (Q/V band) and propagation experiments at both 20 GHz (Ka band) and 40 GHz (Q band) by operating the Aldo Paraboni Payload. The IMS was developed under the Italian Space Agency contract and developed by the Italian industry in accordance with the requirements defined for communications and propagation experiments by two principal investigators, appointed by the Italian Space Agency. The IMS consists of two transmitting/receiving ground stations and three control centers, while the space segment is represented by the Aldo Paraboni Payload, financed by Italy through the ARTES‐8 Program, developed by the European Space Agency and implemented by Italian space industries. The Aldo Paraboni Payload, also called technology demonstration payload #5 (TDP#5), has been embarked as piggyback on Alphasat satellite, an INMARSAT Commercial Telecommunication Geosynchronous satellite successfully launched on 25 July 2013, which uses the ESA‐developed Alphabus Platform and embarks other four technology demonstration payloads (TDPs). This paper presents an overview of the overall system composing the IMS, the functional architecture, main subsystems, and specific features related to the communication and propagation experiments. The ground station validation is also described, together with the description of the system test campaign, performed for functional and performance verification of the IMS. The campaign allowed to test the Q/V band communication functions and to perform the propagation experiment verification, operating the payload in loopback mode and in cross mode.

IPID5196777submitted. The subsystems developed in the course of the project will be tested in a real environment using the Q/V-band Aldo Paraboni (AP) payload on Alphasat (25° east) and its associated ground segment, made available by the Italian Space Agency (ASI). This project has been granted by the European Commission and involves a consortium of companies and universities coordinated by ASI. The consortium consists of: Martel GmbH, Erzia Technologies SL, Eutelsat SA, MBI Srl, Consorzio Nazionale Interuniversitario per le Telecomunicazioni (CNIT), OMMIC SAS, Heriot-Watt University and SkyTech Italia Srl. In preparation of the on-field test campaign using the Aldo Paraboni payload (to be started in July, 2018), two earth stations have been equipped with the QV-LIFT gateways component, whereas a third station hosts the fixed user terminal. This paper describes the preparatory activities carried out to assess the performance of the hardware and software components specifically designed for the Q/V-band satellite communications system. The QV-LIFT project also includes the development of a Q/V-band Airborne Terminal providing a two-way on-the-move communication link for aircrafts. However, this activity is not presented in this paper.

Combining the use of Extremely High Frequencies (EHF) and Free Space Optics (FSO) for the feeder links of future High Throughput Satellites (HTS) is recognized as a key element to optimize system efficiency in terms of costs, power consumption and to increase the data rate to unprecedented levels (Terabit/s). This paper provides an overview of the main challenges to be faced to make the exploitation of hybrid EHF/FSO links feasible and cost-effective. In this framework, propagation and HW impairments mitigation techniques will play a key role. Therefore, the paper also presents a vision on how the use of SDN/SDR and NFV, extended down to lower layers of the protocol stack, could provide novel, so far unexplored, opportunities for optimizing the performance of such mitigation techniques.

With the aim of supporting satellite Terabit connectivity, the future generations of High Throughput Systems — HTS rely on the exploitation of Q/V band frequencies. These frequency bands offer the possibility to have larger bandwidth availability with respect to Ka-band systems, freeing the portion of the Ka frequency band that is currently allocated to feeder links and offering bigger portion of spectrum for specific services, such as the aeronautical in-flight entertainment and connectivity (IFEC) services. The design of a Ground Segment for Q/V band satellite communications presents however several technological challenges. The design of antennas, power amplifiers with high efficiency and Low Noise receivers are critical, nevertheless they are fundamental to support high data rate transmissions. Furthermore, to counteract atmospheric impairments, a system able to implement and manage a handover mechanism between gateways is also needed. A Ground Segment for Q/V band high throughput system has been conceived in the project “Q/V band earth segment LInk for Future high Throughput space systems” (QV-LIFT), funded by the European Commission in the framework of the Horizon 2020 program. The consolidation of crucial technologies for new generation satellite communications is addressed, with the objective to ensure space accessibility to Europe and, in particular, to foster technology readiness of European industries in space related sectors. This paper provides the description of key hardware and software developments for next generation HTS systems operating in Q/V band, based on core technologies for both ground and user segments currently under development for the QV-LIFT project. The system test architecture which will be used to validate the developed technology and functionalities is also presented, together with the overview of the project status and validation plan.

The use of Ka-band is currently the benchmark for High Throughput Satellite (HTS) systems commercial application, while Q/V band is under scientific investigation through a European experimental campaign. The use of Extremely High Frequencies (EHF), in particular "beyond Ka-band" spectrum, is one of the main assets to increase the system throughput, exploiting the large bandwidth availability. The next generation of HTS will exploit these frequency bands (in particular Q/Vband in a shot-term scenario) in the feeder link, while Ka-band will be used in the user link to maintain user terminal backward compatibility. In a long-term scenario, beyond Ka-band frequencies could be used both in the user and feeder links. The impairments caused by propagation of EHF in the troposphere can be very high, hence, research activities on propagation impairments mitigation techniques (PIMT) are needed. The basic of PIMT is the dynamic adaptation of the system to the channel conditions and PIMT control loop is based on the use of channel status estimators. In this paper, different channel short-term prediction techniques will be presented and optimized using real Q/V band experimental data collected during the current Q/V-band satellite communication experimental campaign of Italian Space Agency (performed through the Aldo Paraboni P/L, embarked on Alphasat).

This paper presents a summary of the project: “Q/V band earth segment Link for Future high Throughput space systems” (QV-LIFT), recently funded in the framework of the EU program Horizon 2020. The project aims at developing up to date hardware and software technologies for the Ground Segment of the future Q/V band terabit Satcom infrastructure.

This paper presents a summary of the RF systems currently under development for the project: “Q/V band earth segment LInk for Future high Throughput space systems” (QV-LIFT www.qvlift.eu), that has recently been awarded funding in the framework of the EU program Horizon 2020. One key project aims is to develop up to date hardware and software technologies for the Ground Segment of the future Q/V band terabit Satcom infrastructure. In this paper an account of the developments related to the RF systems is given.