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This contribution is aimed at presenting the scenario of the expected atmospheric impairments suffered by a radio link operating in the W band, as derived by the present theoretical and experimental knowledge. The contributions to signal fade due to gases, clouds, scintillation and rain (with emphasis also on the impact of the hydrometeor size distribution), as well as the melting layer characteristics...
The Long Term Evolution (LTE) is a mobile communication standard that is receiving significant attention, and especially offers positioning capabilities by specifying a dedicated downlink signal, i.e. the positioning reference signal (PRS). Thus, this technology can improve the location of mobile terminals operating in harsh environments, such as urban or indoor scenarios. This paper presents a study...
The return-link of a multi-beam satellite system can be regarded as a multiple-input multiple-output (MIMO) system, with users generating interference to each others. If the number of frequencies in the system (or number of colors) gets low (e.g. down to 1, for full frequency reuse), the level of inter-user interference gets higher, but the bandwidth available to each user is increased. Hence it is...
This paper provides a high level overview of the new SB-SAT technology which is being developed. The terminal and service capabilities deliver a “disruptive” technology which is a paradigm shift in the way data is relayed to and from LEO spacecraft. It will allow the deployment of smaller and cheaper LEO missions that require frequent communication contacts in the near-earth environment. Future variants...
In the recent past, new enhancements based on the well established Aloha technique (CRDSA, CRDSA++, IRSA) have demonstrated the capability to reach higher throughput than traditional SA, in bursty traffic conditions and without any need of coordination among terminals. In this paper, retransmissions and related stability for these new techniques are discussed. A model is also formulated in order to...
Hybrid terrestrial-satellite Single Frequency Networks (SFN) achieve large spectral efficiencies due to a higher frequency reuse, which is attained by transmitting the same waveform in the same frequency band from satellite and terrestrial transmitters. However, the presence of multiple transmitters propitiates the existence of the so-called SFN echoes, which can degrade the system performance even...
This paper presents a new bit-interleaved higher-order APSK scheme for LDPC codes. Although the maximum decoding performance can be achieved using the maximum likelihood (ML) soft detection scheme, the complexity increases exponentially with the modulation orders. We approximate the ML soft detection scheme by applying the hard decision threshold (HDT) based method for a modified constellation of...
The Automatic Identification System (AIS) is a maritime surveillance system using the VHF band to exchange information between ships and shore stations, including positions, identification, course and speed. It mainly aims at avoiding collisions between ships. The link budgets allow receiving transmitted AIS signals from space, and consequently a global maritime surveillance from space can be considered...
In the field of maritime surveillance, the space-based detection of Automatic Identification System (AIS) communications enables ship tracking and fleet monitoring with a global coverage. SAT-AIS is a joint initiative from the European Space Agency (ESA) and the European Maritime Safety Agency (EMSA) to define a sustainable space-based system that will provide AIS data to institutional organisations...
This paper tackles the issue of code acquisition of Spread Spectrum (SS) signals used for Telemetry, Tracking and Control (TT&C) of satellites operating in the Launch and Early Orbit Phase (LEOP). Peculiar to this scenario is the very low signal to noise plus interference ratio, that requires very accurate frequency estimation during code acquisition in order to guarantee the lock of the tracking...
This paper focuses on a novel, conceptual data relay system for relaying data transfer between low earth orbit (LEO) satellites and a gateway through a geostationary earth orbit (GEO) satellite, developed in the framework of the GeReLEO project. Novel channel adaptive transmission schemes are introduced in addition to the access scheme supporting several LEO satellites in parallel. On top of this,...
This paper describes concept and development of some key components for a demonstrator of a multiple-beam antenna used for high-rate data relays. The demonstrator shall validate the whole antenna concept, showing among others antenna multibeam capability and advantages of the deployed digital beamforming.
S-band is used in North America for a successful and growing satellite radio one-way broadcast system. It is currently being expanded and improved to provide localization, personalized and on-demand services. Two way capability to accomplish this will initially be through the internet accessed by cellular telephones, iphones and smartphones. Future improvement for high volume requested returns to...
Automatic Dependent Surveillance Broadcast (ADS-B) is a technology that enables Air Traffic Management (ATM) services by means of aircraft broadcasting signals including flight related information on a regular basis. Terrestrial-based ADS-B infrastructure is already deployed as alternative or add-on to radars. However, it is not feasible for remote, polar, and oceanic areas, accounting for 71% of...
An open ITS platform combining interactive satellite services with other communication channels is being developed and evaluated in field trials within the SafeTRIP project [1]. Prototyping and in-field validation of a novel waveform for messaging return channel over satellite for land mobile is an important objective of the project. The overall system architecture has recently been standardized by...
Peak Signal-to-Noise Ratio (PSNR) is the simplest and most widely used objective video quality evaluation method. However, traditional PSNR calculations do not take packet loss into account thus giving an inaccurate representation of the video quality. Indeed, transmission packet losses may be the cause of visible destructive distortions, which can result in a progressive quality degradation due to...
We address several implementation issues related to multi-user physical layer network coding, in which the symbol-synchronous collision of an arbitrary number of signals is decoded. In particular we study the effect of frequency and phase offsets, the imperfect symbol synchronization of the colliding signals and the estimation of frequency and phase offsets and amplitudes in the presence of more than...
In this paper we present experimental results of the ETSI S-MIM (S-band Mobile Interactive Multimedia) protocol, tested for the first time over a real GEO satellite (EUTELSAT 10A) and through a fully compliant ground platform. In particular, the employed radio interface implements the Part 3 of the standard, i.e. the asynchronous access protocol, especially conceived for the interactive messaging...
This paper summarizes some of the outcomes of an investigation activity aimed at analysing the benefits of different system architectures and technologies for next generation S-band mobile satellite interactive / broadcasting networks. Along with advanced antenna and payload architectures, a promising way forward in this context is the migration from the conventional single polarization per beam to...
This paper presents the design of an intermediate gain S-band antenna with electronic beam steering capabilities. The antenna allows simultaneous reception and transmission of S-band signals and can track the position of a geostationary satellite by electronically switching among a finite set of beams. The tracking system is based on combination of position and attitude sensors embedded in the antenna...
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