Dr. Lorenzo Luini
Lorenzo Luini was born in Italy, in 1979. He received the Laurea Degree (cum laude) in Telecommunication Engineering in 2004 and the Ph.D. degree in Information Technology in 2009 (cum laude) both from Politecnico di Milano, Italy. He is currently a tenure-track Assistant Professor at DEIB (Dipartimento di Elettronica, Informazione e Bioingegneria) of Politecnico di Milano, where he teaches courses on electromagnetic fields.
His research activities are relative to electromagnetic (E.M.) wave propagation through the atmosphere, both at radio and optical frequencies: physical and statistical modeling for E.M. propagation applications; remote sensing of atmospheric constituents using radiometric data; design of wireless terrestrial and SatCom (GEO, MEO, LEO) systems, also implementing Fade Mitigation Techniques (e.g. site/time diversity); performance evaluation of Free Space Optics Earth-space (to satellite or deep space probes) systems; impact of the atmosphere on Synthetic Aperture Radars (SAR); analysis of the performance of spaceborne GNSS receivers.
Lorenzo Luini also worked as a System Engineer in the Industrial Unit – Global Navigation Satellite System (GNSS) Department – at Thales Alenia Space Italia S.p.A.
He has been involved in several European COST projects, in the European Satellite Network of Excellence (SatNEx), as well as in scientific projects funded by the European Space Agency (ESA), the USA Air Force Laboratory (AFRL) and the European Commission (H2020).
Lorenzo Luini authored more than 40 papers published in international scientific journals, for which he also serves as a reviewer (e.g. IEEE TAP - Transactions on Antennas and Propagation). He is an Associate Editor of International Journal on Antennas and Propagation (IJAP), IEEE Senior Member and Member of the Italian Society of Electromagnetism (SIEm).
Future Satellite TLC systems: the challenge of using very high frequency bands.
Telecommunication systems could greatly take advantage from the use of very high frequency bands given their availability for large bandwidth requested by the increasing demand of multimedia services. The smaller antenna size for a fixed gain, or conversely, the higher antenna gain for a fixed size, certainly represent concrete benefits as well. Moreover, the possibility of using on-board antennas with enhanced directivity is attractive to avoid interference in case of frequency reallocation or regional services avoiding interference.
Unfortunately, radiowaves at very high frequency bands (Ka, Q/V and W bands, from 20 to 100 GHz) suffer from detrimental effects caused by the lower part of the atmosphere (troposphere). This is the reason why, with the present technology, it is not realistic to assign such high frequencies to the single user link, usually equipped with a VSAT (Very Small Aperture Terminals). Besides this, at the moment, the bottleneck of satellite high throughput systems is the bandwidth of the gateways, which are equipped with high gain terminals (with a diameter of some meters) that can better counteract the unfavourable atmospheric conditions. In addition, if the gateway operates at higher frequency bands, a large portion the lower frequencies is freed and made available to the increasing request of user link bandwidth. Another foreseen possibility is the use of non-GEO (especially LEO) constellations of satellites taking advantage of reduced time delays and free space loss.
Nevertheless, due to the high attenuation values induced by the troposphere, the design of TLC systems at such frequency bands, and in particular the satellite based ones, cannot be carried out by simply assigning an extra power margin but has to make extensive use of Fade Mitigation Techniques (FMTs). These include classical site diversity (duplication of the gateways at a distance of few kilometres) or on board adaptive power allocation (the on board antenna radiates a shaped beam concentrating more power where needed, on statistical or near real time basis). Moreover, from the telecommunication side, techniques like adaptive coding and modulation (ACM) and data rate adaptation (DRA) are mandatory and a reduction of the Quality of Service (QoS) must be also accepted.
In this talk, we will briefly review the scenario of the possible advanced TLC satellite systems and the frequency bands to be likely used in the near future. The propagation impairments caused by the troposphere, both in nonrainy and rainy conditions, at very high frequency bands will be described together with the new challenges in modelling electromagnetic wave propagation through the atmosphere.
The main FMTs will be also described, together with their typical necessary inputs (in terms of data and modelling).