Wireless and Space Communications

Research focus

The Peer review has evaluated this group as Excellent

Terrestrial and space telecommunications using centimetre, millimetre and optical wavelengths This activity is mainly focused on advanced telecommunication systems utilizing higher and higher frequencies (RF up to 100 GHz and optical) to accommodate for the increasing needs of the modern society in terms of bandwidth (multimedia), ubiquity (digital divide), promptness of intervention (calamities or disasters), systems convergence (internet, navigation, remote sensing), access (last mile) etc. This drives the activity of the group towards theoretical studies and experimental investigations concerning various aspects of the transmission problem with particular emphasis on the tropospheric effects (atmospheric physics, telecommunications aspects, measurements, system design, statistics etc.). The group has access to experimental facilities located at the Politecnico premises (Free Space Optical link) and at Spino d’Adda (big satellite terminals, meteorological radar, radiometers, meteo instrumentation). Data collected at these facilities are being analyzed in order to produce design and analysis tools for future systems, prediction models, proposals to the regulatory bodies (ITU-R, ETSI etc.) and basic telecommunication science. Projects for the realization of future satellite-based experiments in the Ka and Q/V band are currently under way after proposals of the Politecnico di Milano group to the Italian and European Space Agencies (project Technology Demonstrator Payload N. 5). Identification and modelling of the radio-channel properties in the Ka, Q/V and W frequency bands The aim is to develop prediction models for various parameters (such as attenuation depolarization, scintillations, electromagnetic radio-interference etc.) characterizing the tropospheric propagation applicable up to the highest frequencies expected to be used in the forthcoming years: some of these models were developed in the past for lower frequencies and had to be validated up to 50 GHz while some others had to be purposely devised. In order to allow the design of future very large capacity satellite-based telecommunication systems (backbone- or meshed-networks, advanced systems based on adaptive code modulations or adaptive power partitioning) the following models have been created, and validated by the Politecnico di Milano Group: - SC-EXCELL for the prediction of the rain attenuation; - the Synthetic Storm Technique for the prediction of rain attenuation time series and rain attenuation probability distributions; - fade duration statistics; - second-order attenuation statistics for the prediction of the simultaneous occurrence of attenuation in several locations; - methods for the simulation of statistics of any type based on the Spino d' Adda data-set (generation of "exported" time-series); - Rain and ice depolarization prediction model. The validation of these models has been largely based on new extensive worldwide meteorological data, spanning over a period of 15 years, recently collected from Meteorological Offices. Design of advanced satellite-based telecommunication and broadcasting systems at centimetre and millimetre waves 175 The aim of this activity is the one of draw a preliminary design of an advanced satellite-based system covering the European area by utilizing the principle of adaptively distribute power flux over the service area in such a way to optimally counteract, instant by instant, the tropospheric attenuation. The system, supposed to work in the ka band, has been studied in two versions: wideband telecommunications and broadcasting: in the first case a multibeam onboard antenna creates numerous cells (beams) across the served area and the system partitions the power among them according to weather information nowcasted by meteorological offices (European Centre for Medium range Weather Forecast and Eumetsat). In the case of broadcasting, the signal injected in the various beams of the antenna is the same and the antenna acts as a spatial filter contouring the illuminated region (the whole Europe) with a time-variant directivity function tailored on the meteorological perturbances. The performance of the system has been tested over a period of many years by utilizing historical data provided by the abovementioned Offices. The tests demonstrated, for the broadcasting case, a reduction of the non served users of a factor 4 to 6 using the same power on-board or, alternatively, both in the telecommunication and broadcasting cases, a reduction of the necessary power of 2 to 3 dB to obtain a similar performance. Recently, we have also studied the architecture and theoretical performance of the downlink from deep-space spacecrafts for providing links with high availability at high microwave frequencies.

Dipartimento di afferenza

Dipartimento di Elettronica e Informazione (DEI)

Docenti afferenti

Carlo Capsoni (full professor)
Aldo Paraboni (full professor)
Michele D’amico (associate professor)
Emilio Matricciani (associate professor)
Carlo Riva (associate professor)