Papers & Publications

In this paper we study the opportunistic use of microwave satellite signals in the Ku and Ka bands to detect the presence of rain events and to estimate their intensity. This approach, based on measuring the excess signal attenuation due to rain, has the advantage that the potential number of sensors over the territory could be increased dramatically also allowing prospectively the realization of accurate regional rain maps. Moreover, employing the same satellite network whose signals are opportunistically used, the measurements can be easily fed back and universally distributed, contributing to the effective implementation of a nowcasting platform, which could help the timely detection of catastrophic rain events. Results are very promising and show that the already good estimates obtained by using signals in the Ku band can be further improved by using signals in the Ka band. Unfortunately, as of today, the frequency with which the receivers on the Ka band provide signal measurements is too low for fast changing rain events and how to address this problem is the object of future research.

In this paper, we present results from the NEFOCAST Project, funded by the Tuscany Region, aiming at detecting and estimating rainfall fields from the opportunistic use of the rain-induced excess attenuation incurred in the downlink channel by a commercial DVB satellite signal. The attenuation is estimated by reverse-engineering the effects of the various propagation phenomena affecting the received signal, among which, in first place, the perturbations factors affecting geostationary orbits, such as the gravitational attraction from the moon and the sun and the inhomogeneity in Earth mass distribution and, second, the small-scale irregularities in the atmospheric refractive index, causing rapid fluctuations in signal amplitude. The latter impairments, in particular, even if periodically counteracted by correction maneuvers, may give rise to significant departures of the actual satellite position from the nominal orbit. A further problem to deal with is the daily and seasonal random fluctuation of the rain height and altitude/size of the associated melting layer. All of the above issues lead to nonnegligible random deviations from the dry nominal downlink attenuation, that can be misinterpreted as rain events. In this paper, we show how to counteract these issues by employing two differentially configured Kalman filters designed to track slow and fast changes of the received signal-to-noise ratio, so that the rain events can be reliably detected and the relevant rainfall rate estimated.

An accurate measurement and monitoring of precipitation events is closely linked with different applications that have an impact on human welfare such as water resources management, and floods, landslides or wildfire risk assessments. Currently rain gauges, disdrometers, ground-based weather radars and satellite sensors (both active and passive) can be considered the conventional devices for precipitation measurements that are worldwide adopted. These devices have different measurement principles, time and space resolution, and accuracy (Gebremichael and Testik, 2013). In the last decade, a new technology that exploits the microwave satellite links has been investigated to retrieve precipitation information. The idea is to estimate the precipitation starting from the attenuation of the signal along its propagation path. Few studies have been carried out in this direction (such as Barthès and Mallet, 2013 and Mercier et al., 2015), showing promising results. In that regards, recently, an Italian project called NEFOCAST, funded by Tuscany Region (Italy), has been carried out with the aim of estimating rainfall rate from attenuation measurements made available by commercial interactive digital video broadcasting (DVB) receivers, called smartLNBs. During the NEFOCAST project, an ad hoc rainfall retrieval algorithm has been developed, tuned and tested. It allows to estimate, with 1-minute rate, the instantaneous rainfall rate (R, in mm/h) from the ratio η = Es/N0 between the received energy-per-symbol Es and the one-sided power spectral density of the additive white Gaussian noise N0, (Giannetti et al. 2017). To validate the algorithm, a 1-year field campaign (from January 2018 to January 2019) was conducted. The collected data allow to compare the SmartLNB precipitation estimates with the measurements gathered by ‘conventional’ meteorological devices such as rain gauges, weather radar and disdrometer. A network of 24 smartLNBs was deployed in Tuscany, along with 11 rain gauges and one X-band dual-polarization weather radar. Furthermore, the performance of the NEFOCAST algorithm has been preliminarily tested by comparing data provided from one SmartLNB installed at the Institute of Atmospheric Sciences and Climate (ISAC) of CNR in Rome (Italy) with a co-located laser disdrometer. For this site, data from a dual polarization C-band weather radar (Polar55C) could be compared with SmartLNB measurements along the Earth-satellite link. In fact, during the project the Polar55C has been aimed in the same direction as the SmartLNB, with the same elevation angle, thus scanning the same portion of atmosphere where the SmartLNB signal was propagating. Preliminary results show a good agreement between the total cumulative precipitation (in mm) obtained from SmartLNB data and the one collected by the co-located disdrometer during different rainfall events. The corresponding values of Normalized Mean Absolute Error (NMAE) and Root Mean Square Error (RMSE) obtained comparing the total cumulative precipitations obtained from SmartLNB and disdrometer are 41% and 4.71 mm, respectively. Encouraging results come also from the comparison of the total precipitation amounts as measured by the network of SmartLNBs and rain gauges, with values of NMAE (RMSE) that range between 39% and 53% (2.8 mm and 8.0 mm), depending on the specific site.

NEFOCAST is a project funded by the Tuscany Region Goverment (Italy) that aims at setting up, and demonstrating through field experiments, the concept of a system able to provide precipitation maps in real-time based on the attenuation measurements collected by a dense population of interactive satellite terminals (called SmartLNB, smart Low-Noise Block converter) commercially used as bidirectional modems. The system does not require the set-up of specific precipitation measuring instruments, but uses telecommunication links. An algorithm that converts the SmartLNB raw data into attenuation values, and infers rainfall rate from the total signal attenuation provided by the devices and from the knowledge of the link geometry, has been developed. An experimental campaign will take place in 2018 in Tuscany with the purpose of validating the NEFOCAST estimates, obtained through a dense population of smartLNBs and an X-band dual-polarization weather radar, purposely installed. During a preliminary test phase, performance of the algorithm has been assessed tested by comparing data from individual smartLNBs with tipping bucket rain gauge and a co-located laser disdrometer. This study presents and discusses results obtained during the test phase, focusing on disdrometer evaluation.

NEFOCAST is a research project that aims at retrieving rainfall fields from channel attenuation measurements on satellite links. Rainfall estimation algorithms rely on the deviation of the measured E s /N 0 from the clear-sky conditions. Unfortunately, clear-sky measurements exhibit signal fluctuations (due to a variety of causes) which could generate false rain detections and reduce estimation accuracy. In this paper we first review the main causes of random amplitude fluctuations in the received E s /N 0 , and then we present an adaptive tracking algorithm based on two Kalman filters: one that tracks slow changes in E s /N 0 due to external causes and another which tracks fast E s /N 0 variations due to rain. A comparison of the outputs of the two filters confirms the reliability of the rainfall rate estimate.

The request for the provision of services relying on Machine to Machine (M2M) communications have increased a lot over the last years. This has led to the introduction of M2M communications also in the SatCom area. In this context, the design of ultra-low power terminals becomes indispensable. In this paper, a feasibility study for assessing the implementation of an innovative energy efficient technique for ultra-low power M2M SatCom terminals is proposed. By Ieveraging on the E-SSA (Enhanced Spread Spectrum ALOHA) protocol, the newly proposed technique jointly exploits the use of multiple Spreading Factors (SFs) for transmission together with a smart transmission manager which is able optimize the use of energy harvesting by dynamically deciding when and how to transmit data. The proposed solution has been tested in different SatCom scenarios, demonstrating its effectiveness in terms of overall throughput and energy consumption.

In the context of the recent solutions proposed in the 3GPP for standardization group on NOMA (Non-Orthogonal Multiple Access) schemes, this paper discusses different approaches for implementing an approximate spread spectrum MMSE (Minimum Mean Square Error) detector. In addition, the implication of such detectors on the signal design is presented

In this paper, we present a research project named NEFO-CAST, that targets a very-short-term forecasting platform with high accuracy and small-scale spatial resolution. The innovative solution lies in adopting a new generation of interactive satellite terminals, called SmartLNB, that serves both as a weather sensor and the transceiver for the forecasting platform. Throughout the paper, we highlight the main features of the system, including the advantages compared to state-of-the-art solutions, the expected results, and the market perspectives.

In this paper we describe a statistical and a physically based approaches to retrieve 2D rainfall fields exploiting the attenuation measurements made along satellite links at Ka and Ku bands, in the framework of the research project NEFOCAST. The retrieval algorithms, the main results obtained so far, and the on going test campaign are presented and discussed.

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.

In future communication satellite systems the adoption of higher frequencies as Q/V-band (around 40 GHz for downlink and 50 GHz for uplink) is seen as the promising step forward to achieve higher performance in terms of total system throughput. The envisaged usage of these frequency bands, bringing an additional 5 GHz bandwidth in each polarization (10 GHz in total), is dual: as feeder link for Fixed Satellite Service (FSS) systems and as user link for Mobile Satellite Service (MSS) for aeronautical terminals. The QV-LIFT project is paving the road for the future deployment of such Q/V-band SatCom systems, providing core technologies for both ground and user segments. The subsystems developed in the course of the project will be tested in a real environment using the Q/V-band Aldo Paraboni payload on Alphasat 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 the Italian Space Agency (Agenzia Spaziale Italiana, ASI). The consortium consists of: Consorzio Nazionale Interuniversitario per le Telecomunicazioni (CNIT), Martel GmbH (Martel), Erzia Technologies SL (Erzia), Eutelsat S.A. (Eutelsat), M.B.I. SRL (MBI), Heriot-Watt University (HWU), SkyTech Italia SRL (SkyTech), OMMIC SAS (OMMIC). This paper presents part of the project activities, such as the description of one possible future Very High Throughput Satellite (VHTS) scenarios for Q/V-band systems. Furthermore, the technologies currently under development and the system test architecture which will be used to validate the developed technology and functionalities are presented.

We present the NEFOCAST project (named by the contraction of “Nefele”, which is the Italian spelling for the mythological cloud nymph Nephele, and “forecast”), funded by the Tuscany Region, about the feasibility of a system for the detection and monitoring of precipitation fields over the regional territory based on the use of a widespread network of new-generation Eutelsat “SmartLNB” (smart low-noise block converter) domestic terminals. Though primarily intended for interactive satellite services, these devices can also be used as weather sensors, as they have the capability of measuring the rain-induced attenuation incurred by the downlink signal and relaying it on an auxiliary return channel. We illustrate the NEFOCAST system architecture, consisting of the network of ground sensor terminals, the space segment, and the service center, which has the task of processing the information relayed by the terminals for generating rain field maps. We discuss a few methods that allow the conversion of a rain attenuation measurement into an instantaneous rainfall rate. Specifically, we discuss an exponential model relating the specific rain attenuation to the rainfall rate, whose coefficients were obtained from extensive experimental data. The above model permits the inferring of the rainfall rate from the total signal attenuation provided by the SmartLNB and from the link geometry knowledge. Some preliminary results obtained from a SmartLNB installed in Pisa are presented and compared with the output of a conventional tipping bucket rain gauge. It is shown that the NEFOCAST sensor is able to track the fast-varying rainfall rate accurately with no delay, as opposed to a conventional gauge.

This paper describes the evolution of the ETSI S-band Mobile Interactive Multimedia (S-MIM) protocol to support Fixed Interactive Multimedia Services (F-SIM) exploiting existing Ku and Ka-band satellites. The key F-SIM protocol differences for both physical and upper layers are described and justified. The F-SIM protocol has been adopted by the recently deployed Eutelsat Broadcast Interactive System (EBIS) whose architecture, key system parameters, link budget examples and key composing elements are also described. Finally, a summary of laboratory and field trials results over the Eutelsat Ka-Sat multi-beam satellite are illustrated.

This paper describes the evolution of the ETSI S‐band mobile interactive multimedia protocol to support fixed satellite interactive multimedia (F‐SIM) services exploiting existing Ku‐band and Ka‐band satellites. The key F‐SIM protocol differences for both physical and upper layers are described and justified. The F‐SIM protocol has been adopted by the recently deployed Eutelsat Broadcast Interactive System whose architecture, key system parameters, link budget examples and key composing elements are also described. Finally, a summary of laboratory and field trials results over the Eutelsat KA‐SAT multibeam satellite are illustrated. Copyright © 2015 John Wiley & Sons, Ltd.

This paper describes the implementation of the first enhanced spread spectrum aloha demodulator, based on an innovative architecture which combines software‐defined radio with processing via commercial graphics processing units. The validation tests performed both in laboratory conditions and directly on the satellite EUTELSAT 10A are presented. The performance assessment results obtained via satellite validate the theoretical results to a sufficient degree to make enhanced spread spectrum aloha technology a viable option for low‐power mobile and fixed terminals, thus encouraging the growth of satellite mass market applications. Copyright © 2014 John Wiley & Sons, Ltd.

The following paper presents the ACCORD project which is aimed at specifying a complete platform capable of generating innovative terminals able to automatically reconfigure seamless switching between different air interfaces and relevant protocols. The ACCORD solution is a new concept comprising a platform for a family of terminals, which can be easily deployed according to the air interfaces and protocols supported. This truly innovative approach is based on three main features. Firstly a Smart router which provides seamless vertical handover by selecting the most appropriate network based on a Quality of Service policy. Secondly a Hybrid terminal on which both satellite and terrestrial waveforms are present. Lastly a Common Interface which manages the satellite and terrestrial air interfaces and their protocols using a fully Software-Defined Radio approach.

An intelligent transport system open platform integrating the S‐band Mobile Interactive Multimedia messaging return channel protocol over satellite (based on Enhanced Spread Spectrum Aloha) has been developed and tested under real environment conditions within the framework of SafeTRIP, an FP7 EU‐funded project. This paper presents the first field trials results using the S‐band Mobile Interactive Multimedia technology. The introduced forward and return link outcomes have been derived from mobile field trials carried out in the surroundings of the German Aerospace Center (DLR) in Germany. Finally the validation of the system performances has been realized thanks to the use of a traffic emulator that can simulate a large population of Enhanced Spread Spectrum Aloha terminals. Copyright © 2014 John Wiley & Sons, Ltd.

The following paper presents the fundamental aspects of the SATURN initiative proposed by a group of Italian companies active in developing of new solutions which exploit the potential of S-band communications. SATURN is the acronym for “Smart mAritime saTellite terminal for mUltimedia seRvices and conteNts”. Using S-band technology will make it possible to provide new services and contents on board small (10 to 24 meters) maritime vessels where satellite services are not usually enabled. The innovation of the paper is the presentation of a new cost effective solution composed of antenna, gateway and plotter in order to address the maritime market segment not covered by other bi-directional communication satellite solutions. The proposed solution will provide new satellite services currently not available while the boats are far from the coast.

The goal of the ongoing SafeTRIP project is to provide the ITS community with a bidirectional communications platform on which any organisation can develop its own ITS and multimedia entertainment applications. This platform is open to developers willing to benefit from a wide range of state-of-the-art satellite communications services (using the recently allocated S-band spectrum for Mobile Satellite Services and based on standards co-developed by several SafeTRIP partners), as well as almost ubiquitous terrestrial communications networks. It is also available to researchers who wish to exploit its flexibility and open standards, as well as its advanced communications capabilities. This paper briefly presents the platform architecture and focuses more specifically on case studies exemplifying the development process for three different applications. It also shows how to capitalise on the enabling functions of the platform to streamline development Finally, a number of challenges specific to the automotive environment are analysed.

Satellite communication can empower ITS to deploy safety critical services and services of the future, while reaching an unprecedented large number of road users in an eco-friendly and economical way. The SafeTRIP project embraces S-Band communication, creating a powerful and flexible open platform for services that road users need. In this paper, we firstly present an overview of the SafeTRIP project, the salient aspects of the platform and its communication infrastructure. Secondly, we emphasise on the focus the project has on user needs to shape services that would be supported by the SafeTRIP open platform. Finally, we describe the subset of services that have been selected on their relevance to road safety which will part of the trials and demonstrators within the project. We conclude by describing the road map and the project evolution in future.