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In 2004 ASI funded phase-A of the WAVE satellite mission, a feasibility study to design and develop a W-band geostationary payload. The aim was to perform experimental studies of the W-band channel and possible utilization in satellite data communications and data-relay services. The next phase of this project will address the experimental-only nature of W-band and the strategic relevance of making investments towards the development of the payload by performing preliminary experiments, such as the Aero-WAVE mission. The Aero-WAVE mission is presented as a basic test to provide the necessary measures leading to the development of the primary mission into GEO orbit. Aero-WAVE is a scientific payload that operates in W-band. It will be embarked on-board a stratospheric platform or High Altitude Platform (HAP) in order to perform a first test of the channel behaviour at an altitude of about 20 km. The stratospheric platform is a high altitude aircraft known as the M-55 Geophysica, a Russian aircraft well known in the atmospheric research environment and the European scientific community since 1996. The M-55 Geophysica will be equipped with the payload instrumentation to carry out the measurements. These measurements and the resulting data provided throughout the Aero-WAVE mission will give good indications of the channel behaviour at different weather conditions and at different locations within the GEO-WAVE coverage. [ABSTRACT FROM AUTHOR]

Flower constellations are a particular set of satellite constellations where every satellite covers the same repeating space track. When the flower constellations are visualized on an Earth centred earth fixed reference frame, the relative orbits shows flower-shaped figures centered on the Earth. In this paper the shape and the position of a particular flower constellations has been designed for the provision of telemedicine services. Once that performance metrics of the constellation have been defined and the service targets have been identified, the performance of the flower constellation have been compared with the well known polar and Walker constellations. The particular properties of the flower constellations allow an optimized coverage of a list of targets. It was found that the flower constellations provide better performance in terms access availability and mean access time. [ABSTRACT FROM AUTHOR]

The aim of this paper is to describe a toolset named MARKAB, recently developed to analyse the EGNOS Signal in Space. This toolset is intended to analyse the performance that can be obtained using the augmentation navigation system in civil aviation user community. We demonstrate the utility of MARKAB by processing SBAS Signal in Space logged with an EGNOS/WAAS dual frequency receiver installed at our monitoring station. Latest results show that MARKAB establishes an important improvement in the analysis of Required Navigation Performance to the augmentation system, contributing with a new technique to assess the performance in term of Continuity of Service. [ABSTRACT FROM AUTHOR]

The specific interest of Telespazio towards spacecraft radio-assisted navigation does not only concern with the traditional "user segment", but the development as well of ground segment components able to support the space missions with an accurate orbit determination. Spacecraft platforms already exist, and are planned to be launched, including on board GPS receivers, thus providing the capability of processing related raw data to attain a quite precise reconstruction of the satellite dynamics. In the proposed application, it is assumed that measurements zk are provided of a non-linear dynamic system that represents the orbit motion of a LEO spacecraft; the observation samples originate from a dual-frequency (L1/L2) GPS receiver available on-board. The described solution allows to estimate the state vector x, that includes at least position and velocity of the satellite, with a sequential processing which avoids the calculation of any Jacobian or design matrix and thus suppresses the need of reconstructing any derivatives of plant model equations. It is attained through the use of the so called "Unscented Filter" (UF). The proposed algorithm is tested with real data, consisting of raw navigation observables and post-processed reference orbits available from Champ satellite mission. CHAMP (CHAllenging Minisatellite Payload) is a German small satellite characterised by near polar, low altitude orbit for geoscientific and atmospheric research and applications. Among the other problems, a critical aspect to be faced is that one of "outliers" detection and elimination from the orbit determination process; the selection of "proper" signals to be treated is performed in the frame of the sequential calculation, so that only a single "pass" is performed on available raw data. This means that the overall approach is a good candidate as well for a real-time determination of the state vector. As a conclusion, the UF algorithm has proven to be a working and robust solution, even starting from a bad initial approximation of the state vector, whilst this is typically not the case for an Extended Kalman Filter (EKF). [ABSTRACT FROM AUTHOR]

Telecommunication systems based on wireless technology (Wi-Fi, WiMax, Sat DVB-RCS, etc.) offer more than others systems, the opportunity to provide a wide range of broadband services and applications. There are some circumstances where these systems contribute to solve the problem of need of communications such as, for example, for communication restoration during emergencies and catastrophic events as well as for communication services deployment in rural suburban areas typically affected by "digital divide". This paper presents a proposal for an unique integrated wireless network system, mainly based on TCP-IP protocol, which provides a wide range of applications like voice, video, internet browsing, data access, etc. A specific section of the paper is dedicated to WiMax technology and, to evidentiate the performances of this innovative technology, some results of the trials carried out in Italy in 2005-2006 by Fondazione Ugo Bordoni (FUB) and Ministry of Communications, are reported. [ABSTRACT FROM AUTHOR]

One among the most recent configurations in satellite architectures, is enhanced with respect to the traditional ones, by the presence of HAPs (High Altitude Platforms). Those balloons are located at stratospheric altitudes, and make possible to separate the link from LEO to ground into two segments: the former crosses the highest levels of atmosphere and can be developed by optical technology, the latter is more sensitive to scattering and absorption, since it crosses lower atmosphere, so it must be carried out in RF domain where more consolidated technology can be used. The insertion of HAPs in the global architecture enhances the system performance in terms of LEO-Ground link capacity, connectivity and flexibility; in addition the wide band-width offered by optics makes more and more effective those improvements. Even better results can be obtained if a proper coding system is designed. [ABSTRACT FROM AUTHOR]

In this paper an original detection strategy for Satellite Digital Broadcasting communications is definited: particularly, we consider the DVB-S2 system, which is proposed as a development of the DVB systems and exploits iterative decoding and higher order modulation; these features allow the derivation of advanced detectors which are based on an iterative demapping and decoding approach. The adoption of this strategy approaches permits a remarkable performance gain and an improvement of the system throughput. [ABSTRACT FROM AUTHOR]

The continuous increase in Satellite resources demand, especially in Government and Military missions, led to both efficiently use the Satellite Bandwidth/ Power resources, as well as differentiating frequency Bands. The attractiveness of the highest frequencies in terms of reduced antenna dish size, maintaining terminals with good throughput performances, induced us to develop an EHF DVB-RCS Terminal for Government and Military use. This paper describes the Terminal and Network architecture, the overall performances obtained and the future developments planned in this area. [ABSTRACT FROM AUTHOR]

The future hybrid satellite/terrestrial networks are challenged to provide different end-to-end Quality of Service (QoS) classes to the users. In particular, it is expected that QoS routing procedures are implemented, in order to decides the best route to the destination and optimize resource distribution through the path. This fact arises the question of a common representation of the QoS levels such that they can be compared and combined. It was shown in the literature how they can be mapped into a single parameter, the so-called virtual delay. We present and investigate the computational complexity of two approaches to distribute the virtual delay over the communication path (i.e., allocating the resources) in order to guarantee a QoS performance requested by the user minimizing the cost of the provided service. The former consists of a joint routing/resource allocation optimization. The latter assumes that the selection of the path is correctly performed and models the resource allocation problem as an equality constrained convex minimization problem. [ABSTRACT FROM AUTHOR]

In the recent years, systems devoted to access remote laboratories through a networking infrastructure have been actively studied, and a number of specific software platforms, able to manage the instrumentation, have been proposed and implemented. Nevertheless, the problems involved in controlling remote devices on board satellite laboratories or in accessing remote equipment via satellite links are still not sufficiently investigated. The paper briefly introduces the architecture developed within the Labnet project, especially as concerns its core software component, whose aim is providing unified access to heterogeneous equipment for a multiplicity of users. Since the use of an earth-to-space link can possible affect the overall performance of systems based on a TCP-IP suite, a number of tests has been carried out, in order to evaluate the effectiveness and robustness of the proposed solution. Furthermore, the results regarding the performance of the Labnet platform are discussed and compared with those achieved by exploiting the facilities offered by a commercial and very popular software package. [ABSTRACT FROM AUTHOR]

The extension of telecommunication frontiers towards deep space scenarios has opened new horizons in the way of designing network infrastructures and has raised the necessity of developing novel communication paradigms, more suited to this specific environment. Under this view, given the hazardous operative conditions (very large latencies and frequent link disconnections), in which the exchange of data among remote peers has to be performed, the exploitation of TCP-based transmission schemes does not offer satisfactory results. On the contrary, the use of erasure coding schemes and more appropriate Automatic Repeat reQuest(ARQ) schemes, available within the Packet Layer Coding-based and the Consultative Committee for Space Data Systems (CCSDS) protocol architectures respectively, assure better performance results. In this paper, the adoption of erasure codes within CCSDS protocol stack is considered and its effectiveness is evaluated with respect to ARQ-based transmission schemes available within the CCSDS File Delivery Protocol. Finally, the combined use of erasure codes and ARQ schemes is proposed in order to improve the overall performance. [ABSTRACT FROM AUTHOR]

In this paper, the performance of switch and stay combing (SSC) diversity receivers operating over correlated Ricean fading channels, is studied. By representing the bivariate Ricean distribution as infinite series the probability density function (PDF) of the SSC output signal-to-noise ratio (SNR) has been derived. Capitalizing on this PDF the moments of the output SNR and the corresponding cumulative distribution function (CDF) have been also obtained. Furthermore, an analytical expression for the moments generating function (MGF) is derived and by employing the MGF-based approach the average bit error probability (ABEP) for several modulation schemes is studied. Finally, various performance evaluation results, such as average output SNR (ASNR), amount of fading (AoF), outage probability (Pout) and ABEP are presented. [ABSTRACT FROM AUTHOR]

The paper addresses the Integral Satcom Initiative, a European Technology Platform devoted to the entire field of Satellite Communications. The scope, status, and future plans of ISI are outlined in the paper. [ABSTRACT FROM AUTHOR]

VeRT (Vehicular Remote Tolling) is a research program cofunded by GALILEO Joint Undertaking in the framework of the Activity C first call: Introduction of GALILEO services Using EGNOS GJU/03/118/issue2/OM/ms, 2003 31st July. The program belongs to the GJU activities aiming at the APPLICATIONS RESEARCH coming from the EGNOS and GALILEO employment, which are competitive with respect to the only GPS system usage. VeRT belongs to the "Road Applications" area and in particular it focuses on research of applications, sustainable from the economic and social point of view, either for enhancing the "Road Tolling" services or for introducing new added value services to be employed in the "mobility" field only by employing GALILEO. The VeRT programme aims at exploiting the capabilities offered by Galileo to provide new applications in the road sector, by means of the EGNOS system for demonstration purposes; specifically, an extended service concept of road tolling: it is indicated as "remote tolling", such to cover basic tolling service, but also additional "pay-per use services" on motorways transport, as well as in urban environment (parking and access to restricted zones) or in both the environments as the pay per use insurance. The higher level of accuracy and integrity provided by GALILEO (respect to the GPS-only) represents an essential condition connected with the services. From a general point of view, the users must be sure that they are paying for the offered service they are using, thus the right positioning of the users and the guarantee of the service provided assumes an important role in the service architecture. The adoption of a satellite based toll and road services facility in the infrastructural approach, opens the way to further commercial opportunities. This aspect is taken into right account within the VeRT project: a market analysis has been conducted in which revenue mechanism for the service provision has been estimated by analysing market opportunities and defining the opportune marketing strategies. [ABSTRACT FROM AUTHOR]

In this paper we analyze the performance of Filtered Multitone (FMT) modulation systems in satellite channels. FMT is a generalized OFDM scheme that deploys sub-channel shaping filters. It is a spectral efficient scheme that can support orthogonal multiuser transmission. Herein, we carry out a detailed analysis to understand whether it yields increased robustness, compared to OFDM, in typical LEO satellite channels. We consider an asynchronous multiuser scenario that introduces carrier frequency offsets, time offsets, and time/frequency channel selectivity. The analysis that we present in this paper allows to benchmark the multitone system and understand how robust it is to frequency selective time-variant fading and carrier Doppler shifts. Quasi-closed form expressions in the case of rectangular frequency domain pulses and raised cosine pulses are derived for the signal-to-interference power ratio at the receiver. It is found that the sub-channel spectral containment of the FMT system can yield increased performance compared to OFDM. [ABSTRACT FROM AUTHOR]

In this paper we analyze the emergence of new system architectures and products that are able to deliver broadband services into mobile environments using Ku-band. In particular, we analyze the latest technological solutions that have been developed to cope with the stringent requirements of a mobile environment. Such solutions have brought broadband to environments such as business jets, commercial aircrafts, trains, and cars, which are today the new frontiers where broadband MSS can be offered. [ABSTRACT FROM AUTHOR]

Direct reception of DVB-S (2) satellite signals from mobile terminals equipped with non directive antennas is becoming of great interest among manufacturers and operators. Low orbit constellations are technically preferred for mobile terminal reception due to the reduced path loss. Economical issues however, have recently redirected the interest to medium and geostationary constellations, eventually assisted by high altitude platforms. The satellite power is limited by technology and the maximum allowable mass of satellites. This work explores the opportunity of application of link cooperation techniques for downlink reception of DVB-S (2) bitstreams. [ABSTRACT FROM AUTHOR]

The reasons for the growing interest in reconfigurability is motivated and supported by a technology evolution of signal processing components, such as analog-to-digital and digital-to-analog converters, signal processors and FPGAs, available in the market with ever increasing performances and lower power consumptions. Reconfigurability however is expensive, in terms of development costs, power consumption, computational efficiency of devices, so not all radio systems may benefit from this innovative design. The selection of convenience areas is a tough task. Each communication context, satellites being one, has to be properly analyzed before making the decisions. We try in this paper to analyze the potentials of Software Radio for space applications, where large investments but also large risks are present. [ABSTRACT FROM AUTHOR]

The Carrier Pairing technique, i.e. the sharing of the same frequency band for both Forward Link and Reverse Link carriers in a star or multi-star satellite network, is here discussed. In particular a possible mechanization and its performance in a realistic reference scenario are discussed to understand the merits and limitations of that technique. The analyses herein presented were carried out with regard to a reference scenario featuring a single Hub station per spot transmitting a standard DVB-S2 carrier with Adaptive Coding and Modulation (ACM) to User Terminals, which in turn transmit enhanced DVB-RCS signals (Turbo-Φ code, QPSK-16APSK ACM) to the Hub. Impairments caused by the non-linear satellite channel on echo canceller performance have been taken into account, also attempting to mitigate them by means of pre-distortion techniques. [ABSTRACT FROM AUTHOR]

The paper formalizes and analyzes the bandwidth allocation process over space communication systems modelled as a Multi — Objective Programming (MOP) in presence of Quality of Service (QoS) constraints. The reference allocation scheme considered is based on GOAL programming and is called "Minimum Distance" algorithm. The work proposes two different versions of the Minimum Distance scheme both aimed at assigning the bandwidth so to approach a noncompetitive situation as close as possible and at guaranteeing a fixed performance for each traffic flow traversing the space network. The proposals have been tested over a faded channel by using TCP/IP traffic. The performance evaluation is carried out analytically by varying the degradation level of the channel. [ABSTRACT FROM AUTHOR]

Since last decade the satellite industry is experiencing growth in advances of satellites in navigation and telecommunications industry. A range of future broadband, navigation, communication and earth observation services are being developed using next generation system architectures transforming the satellite communication and navigation networks for this century and beyond. These various services as shown in Fig. 1 include the following key characteristics [ABSTRACT FROM AUTHOR]

The necessity of a navigation system, more flexible and interoperable, has become more and more important and the use of satellite system has been recognized as the main means to obtain this improvement. In the aeronautical field the GNSS has been chosen by the ICAO as fundamental component for the future CNS/ATM systems because of its peculiar characteristics that provide the necessary assistance during all flight phases. The ATC interface developed in the frame of EtoG aims to facilitate the introduction of GNSS services in Italian airspaces. The EtoG programme is a programme for researching and developing of new aeronautic applications to optimize the existing procedures and to find new technologies for the management of critical situations (safety) by using satellite navigation. The introduction of satellite navigation (GPS-EGNOS-GALILEO) allows the management of the aircraft flying phases with remarkable advantage compared to the traditional systems. [ABSTRACT FROM AUTHOR]

Modernised GPS and Galileo are going to provide, standalone or through code augmentation systems, meter level accuracy. Such accuracy is commonly considered sufficient for the most of the applications. Nevertheless, other higher accuracy applications like Geodesy, Cadastral Surveying, Mapping, Marine surveying, etc. are still stable niche markets. New applications, as High Precision Cartography and ADAS, are emerging. As in any business, the more the offered service precision will be, the more the precision requirements improve. Centimeters level high accuracy is currently achieved through GPS Reference Stations Networks and the integration of mobile terrestrial or satellite communication systems for corrections broadcasting. The weakness of such systems, in RTK mode, are very well known: low density Reference Stations networks coverage for large areas, not homogeneous performances, not reliable communication systems coverage, not guaranteed reliability of the positioning, complex positioning and communication integrated devices, absence of a comprehensive Business Model. A regional Network backbone design in terms of Reference Stations distribution and separation is needed, integrating existing subnetworks developed for Geodesy, Land Surveying, University research, Marine applications, etc … Network spacing is highly dependent on spatial-correlated errors, but MRS/VRS and innovative WARTK approaches, together with three-frequencies availability and TCAR algorithms, will allow to get real instantaneous and homogeneous solutions at large scale. Tight integration with Communication systems is essential for delivering a reliable Real-Time service. Availability of higher mobile communications (e.g. WIMAX) is opening new doors for that. Furthermore, the future availability of a standardised backbone of Galileo Local Elements will provide a great impulse to such integration. Galileo is also studying Business Models for such Services, starting from the availability of innovative services (e.g. Service Guarantee and SoL). An analysis about GNSS High precision services perspective and interoperability has been performed from different applications points of view, including Galileo future services. [ABSTRACT FROM AUTHOR]

Due to European on-going developments (EGNOS, GALILEO), satellite navigation is now an interesting innovation for all fields of transport. One of them is the railway domain, which could considerably profit from the implementation of autonomous on-board positioning systems. For railway transportation, satellite navigation offers new opportunities to increase accuracy of positioning and to implement safety standards everywhere, from high speed trains to local and regional railway lines, enabling a cost-effective modernization and increase of efficiency. Train control poses high demands on positioning with respect to availability, reliability and integrity. Meeting these requirements with a GNSS-based navigation system is the objective of several projects and still needs to be proved. RUNE is a project developed for the European Space Agency by Alcatel Alenia Space Italia (Laben Directorate), leading a team comprised of VIA Rail Canada Inc. (VIA), Ansaldo Segnalamento Ferroviario (ASF), and INTECS HRT. In this project, the European Geostationary Overlay Service (EGNOS) has been used as part of an integrated solution to improve the train driver's situational awareness. RUNE integrates positioning sensors with signalling and speed constraint information from a control centre. This can improve safety as a result of a better situational awareness and can also speed up the deployment of drivers on new routes. The primary objective is to demonstrate the improvement of the train self-capability in determining its own position and velocity with limited or no support from the track side, still complying with European Railway Train Management System (ERTMS) requirements. The achievement of such objective could lead to the reduction of physical balises distributed along the track line and needed to reset the train odometer error. Substituting physical balises with GNSS-based virtual balises can lead to reduction of infrastructure costs. The RUNE project development has gone through a HW-In-the-Loop laboratory set-up up to field-testing. Field tests of the equipment were performed in Italy on the Torino-Chivasso line in April 2005, on board a Trenitalia ALE-601 experimental train. The unit included an LI GPS/EGNOS receiver, Profibus and CTODL interfaces to the train odometer and BTM, an IMU sensor for dead-reckoning positioning, virtual balise and velocity profile databases. This paper presents an overview of RUNE and provides results of the analysis performed on the data collected from the experimental train test campaign. Although testing duration was limited, collecting and analysing real data is important for building expertise in system behaviour and for algorithms evaluation and tuning. Those initial results show achieved performance in the real environment and the capability of the system to provide In-Cab Signalling and Virtual Balise functionalities. It is recognized that only through extensive field testing and validation of the system architecture and algorithms it will be possible to build a robust certifiable GNSS-based train navigation system. [ABSTRACT FROM AUTHOR]

This work aims to provide the status and the outcomes of the GNSS Bit-True Signal Simulator (GBTSS) software that is developed, and now it is under completion and optimization, in the Navigation & Integrated Communications Business Unit of Alcatel Alenia Space Italia. This simulator provides the I & Q samples of any GNSS signal as seen at the correlators input of a GNSS receiver. [ABSTRACT FROM AUTHOR]

The increasing demand for frequency locations with high bandwidth to satisfy the growing satellite communications applications made it necessary to explore higher and higher frequency ranges. W-band (75-110 GHz) can be considered as the new frontier of satellite communications. Based on the experience gained by Oerlikon Contraves in the development and in the operation of a W band radar sensors operating at 95 GHz for Airport Surface Movement Control and Guidance and on W band point to point ground communication link modular "core" integrated modules based on MMIC technology are described on this paper. The main targets to reach for each "core" module are the minimisation of mass, volume and the modularity in order to have the possibility of use it in payloads that can be embarked on different platforms (nanosatellites, microsatellites, satellites, rovers on Moon and Mars. …) or used on ground for different applications including security. The personalisation of the payload will be done by the antennas, the HPA and the baseband processing depending if the application will be a high rate, high speed communication link or a beacon for propagation measurement or a radar (traditional, SAR, interferometer. …) [ABSTRACT FROM AUTHOR]

This paper deals with the study of low-cost efficient techniques of GNSSINS integration for the realization of a surveillance system for the terrestrial vehicular traffic in an airport. This system will have to enable accurate, continuous and reliable tracking of each ground vehicle operating in airport area in support of maintenance and management of aircrafts. High accuracies are required to give the ground control a precise and dynamic view of the airport situation, in order to optimize the ATM (Air Traffic Management) activity; this is particularly important in large hubs. In order to integrate satellites and sensors measurements we relied on Kalman filtering, a powerful signal processing tool for optimal blending of heterogeneous data sources. Specifically, we used an integration architecture named tightly coupled, where only one Kalman filter is used to integrate pseudorange, Doppler and sensor measurements. We will show that our hybrid receiver is a rather simple but extremely efficient solution to this problem. [ABSTRACT FROM AUTHOR]

Common view (CV) is a well known synchronization technique usually adopted to determine synchronization values to be analyzed in post processing to monitor clock stability. In the Italian GALILEO Test Range (GTR) project, a near real-time, CV based, synchronization technique has been implemented to ensure performance and reliability of test services offered to the GTR users. [ABSTRACT FROM AUTHOR]

Earth crust deformation continuous monitoring using Global Navigation Satellite System (GNSS) local geodetic networks demands suitable computational and informatics tools based on solid scientific background. This is particularly true if geophysical applications are concerned. Applications like seismic hazard mitigation, subsidence and landslides monitoring requires the highest accuracy in positioning with as short as possible measurements sessions length. The GEOLOCALNET project, co-funded by the Galileo Joint Undertaking (GJU) under the 6th Framework Program and managed by a consortium of Research Unit (RU) and Small and Medium Enterprises (SME), investigates the three carriers based Galileo Satellite System positioning capability developing and validating innovative algorithms, models and estimation procedures. The project addresses many and critical issues affecting precision and stability in GNSS processing strategies and promotes the usage of local geodetic networks for deformation evolution monitoring. [ABSTRACT FROM AUTHOR]

The GTR (Galileo Test Range) project is an initiative of Regione Lazio in the frame of its support to technical research and innovation in satellite navigation. Its main target is the development of a laboratory for the test and analysis of the Galileo signals, the support for development, test and certification of user terminals (GPS, EGNOS, Galileo) and of applications in different user domains. The Phase A of the project started on July 2005. the regional Financial Investment Agency dedicated to the support of innovation. In the phase A, the C.A. has the responsibility of developing an infrastructure able to acquire and process signals coming from a constellation of pseudolites, from GPS, from EGNOS and from GSTB V2 satellites and able to support the testing of applications demanding high accuracy positioning providing augmentation to the users in the covered area. Actually the proposal of constituting a center of excellence for satellite navigation follows the strategy of growth of industrial and technological capabilities in the frame of an industrial development policy pursued by Regione Lazio. [ABSTRACT FROM AUTHOR]

This article is the written version of an introductory presentation made at the Opening of the Workshop session entitled "Satellite Navigation: Prospects and Applications". The paper describes the present GNSS scene, which has changed significantly with the successful launch of GIOVE A, the first Galileo test satellite. A summary description of the planned modernisation and governance of the two existing global systems, GPS and GLONASS, is followed by brief details of the proposed Galileo Public-Private-Partnership (PPP) scheme, and a brief summary of the various regional Space Based Augmentation Systems (SBAS). The paper then concentrates on the proposed control of operations and governance of Galileo, a summary of the proposed Galileo services, and the applications that are likely to emerge in the near future. [ABSTRACT FROM AUTHOR]

The aim of this work is to analyse, implement and test different acquisition algorithms for the European Global Navigation Satellite System Galileo signal. The focus of the work is on the L1 signal and the target of the acquisition algorithms is mainly relevant to a Software Receiver Application. Both GPS signal and Galileo signal have been taken into account in order to perform a comparison between these two systems, in terms of computational burden and acquisition sensibility. The motivation of this work comes from the actual tendency of studying algorithms for the realization of a software receiver for the GPS signals (whose principal characteristics are a good flexibility, when compared to the hardware solution, and the possibility of getting "on the fly" updates), and it's aim is to bring advantages of software-based approach to the new Galileo system, in particular for the acquisition schemes of the L1 signal. The principal fact is that acquisition has to be performed on a normal PC, without using a dedicate hardware. In this context, have been developed different acquisition schemes to provide an analysis on their performance, regarding to a software acquisition. All the schemes are finally compared: then, real advantages of employing BOC (Binary Offset Carrier) digital modulation are investigated, provided that this modulation has been developed to transmit GPS and Galileo signals over the same bands to obtain a greater degree of compatibility and interoperability between the two systems (and the L1 signal represents, in this way, the principal example of such interoperability). [ABSTRACT FROM AUTHOR]

The GIRASOLE Safety of Life Receiver is developed in the frame of the Galileo Joint Undertaking (GJU) Research and Development activities, in the context of the European Commission 6th Framework Programme 2nd call by ALCATEL ALENIA SPACE Italia (AASI), manufacturer leader of advanced, high performance GPS/EGNOS/Galileo receivers for space and safety-critical applications. Differently from GPS, which relies on an external signal (EGNOS), one of the most appealing features of Galileo is the signal embedded integrity. As this characteristic provides the users with information about the availability and correctness of the Galileo system and signal, Galileo is particularly attractive for all the critical applications that undergo the general name of Safety of Life, or SoL for brevity. The Safety of Life Services (SoL) are targeted at users who need assurance of service performance in real-time. Typically they are safety critical users, for example Aviation, Maritime and Rail, whose applications or operations require stringent performance levels. Other applications can be envisaged like emergency and road. In these types of applications, the receiver plays an important role since is one of the key elements of the safety chain. The main characteristic of such type of receivers is their capability to detect failures that can come from different sources like the Signal In Space, the environment (ionosphere, troposphere, interference and multipath effects), the constellation etc. and be capable to interpret the integrity information broadcast by the satellites. In the frame of its 2nd Call, the Galileo Joint Undertaking (GJU) has launched several activities aiming to provide basic technological elements (i.e. receivers) useful for the different services offered by Galileo. Within this frame, GJU has selected the GIRASOLE project as the one aiming at development of receivers for SoL application. In the framework of the project, Alcatel-Alenia-Space Italia S.p.A. (AAS-I) is leading a Consortium of several companies from eight different countries all over the world. The GIRASOLE project aims to allow strategic developments of technologies and basic elements of a Safety of life (SoL) Galileo Receiver. The GIRASOLE system architecture is based on GARDA heritage, a project developed by AASI-Milano under GJU contract (1st call) with the key objective to build an advanced user receiver prototype, configurable to simultaneously track Galileo/GPS/SBAS satellites, supporting all Galileo frequencies and modulations. The possibility to have Galileo receivers prototypes available at an early stage will provide benefits for standardization and certification of the receivers within each user communities, while facilitating the market penetration of Galileo. The receiver processes Galileo signals on the L1, E5b bands and GPS/EGNOS signals on the L1 band. It also provides combined Galileo + GPS Navigation solution, Integrity calculations (HMI, critical satellite prediction and Navigation warning) using Galileo and EGNOS Integrity message, interference and multipath mitigation, support to the use of Local Elements and output raw measurements data of each satellite. [ABSTRACT FROM AUTHOR]

The Galileo IOV (In Orbit Validation) Phase is an intermediate step of the Galileo system deployment. The main objective of the IOV Phase is to demonstrate that the Galileo Full Operation Capability (FOC) requirements (as specified in the Galileo System Requirements [2]) can be met, with the support of analyses and simulations, before to complete the deployment of the full system. To this respect, the IOV is a "break" in the deployment to get sufficient confidence that the final system will properly work. [ABSTRACT FROM AUTHOR]

As part of the European GNSS Galileo project and in particular of the Galileo Mission Segment (GMS), the Precise Timing Facility has started C/D/E1 phase under the conduction of the Consorzio Torino Time (CTT). The PTF is in charge of the generation of the Galileo System Time with full unmanned operations remotely controlled by the the Galileo Asset Control Facility. It works in cooperation with an entity external to GMS, the Time Service Provider but is capable of full autonomous generation of GST in lack of the TSP. This paper presents key issues of the PTF technology and performance. It reflect the author's view, without obligation of GMS, GaIn and ESA customers. [ABSTRACT FROM AUTHOR]

This paper presents the first results obtained processing the Signal-In-Space broadcast by the Galileo In — Orbit Validation Element A (GIOVE-A) satellite, the first experimental Galileo satellite. The paper analyzes both the acquisition and tracking phase of a Galileo software receiver able to process raw samples of the signal collected by means of a commercial front end. Starting from the description of the system set up used to collect the data set the paper introduces the Partial Correlation approach adopted in the acquisition phase and describes the tracking structures used to synchronize the local and the incoming codes. Techniques tailored to the new structure of the Galileo signal have been employed. In fact, the GIOVE-A signal uses novel modulation schemes and it is made of longer spreading codes that required modification to both the acquisition and tracking algorithms usually implemented within a GPS receiver. [ABSTRACT FROM AUTHOR]

Recent experiments have shown that a valuable way to monitor the quality of the signal broadcast by Global Navigation Satellite System (GNSS) satellites is to use a high gain antenna. Signal monitoring experiments are important to check the health of the electronic devices on board of the satellite just after the launch, but also to characterize the signal quality over time. In fact, for high performance applications such as Global Positioning Systems (GPS)-based aircraft navigation and landing systems, even small errors due to signal distortions must be considered in the error budget. This paper describes the experiment performed in Green Bank, West Virginia (U.S.A.), where a 110 meter high gain antenna has been used to track several GNSS satellites. After the description of the system set up, the paper will present interesting results obtained in post processing through a toolset, specifically developed for this type of analysis. [ABSTRACT FROM AUTHOR]

In this paper a detailed evaluation of the performance of the architecture named "Turbo Delay Lock Loop" (TurboDLL) is presented. Such an architecture has been introduced by the authors in [1], as an innovative solution for improving the performance of satellite navigation receivers in multipath affected scenarios. The relevant innovation resides in the fact that the architecture aims at tracking each multipath component and, after a transient time, use them to wipe the multipath components off the input signal. The iterative procedure allows for a major improvement in the error induced in the code-based pseudorange measurement. The architecture uses a preliminary estimation of the propagation channel in terms of number of not negligible reflections, and of their relative amplitude. In this paper the robustness of the TurboDLL architecture with respect to imperfect channel estimation is demonstrated. [ABSTRACT FROM AUTHOR]

After the successful launch of the first experimental Galileo satellite, i.e. GIOVE-A, and after the signature of the Galileo-IOV-CDE1 contract, the constituted European enterprise consortium is working hard in order to achieve the Galileo In-Orbit-Validation by 2009. During this IOV phase, the first four operational satellites will be launched and the ground segment will be set up and validated, including the development of the first test user receivers. After an introduction on the Galileo overall system, this paper will describe the Galileo receivers under development in the frame of the IOV contract, focusing on the impacts of the Galileo system requirements towards the receivers design. [ABSTRACT FROM AUTHOR]

The European Space Agency (ESA) and the Surrey Satellite Technology LTD (SSTL) have completed the on-orbit preparation and activated the payload of GIOVE-A, the first Galileo satellite launched last December, the 28th. After successful launch and platform commissioning achievement, GIOVE-A started signals transmission on 12 January 2006. For the time being the quality of the signal broadcast by GIOVE-A is under examination by mean of sophisticated equipments and facilities, including the ESA ground station in Redu (Belgium) and the Rutherford Appleton Laboratory (RAL) Chilbolton Observatory in the United Kingdom. It is clear that the European Galileo satellite navigation system is moving into a crucial phase concerning the development process; therefore the possibility of testing and validating hardware/software tools (e.g. user receivers) will play a key role from the manufacturers point of view. In this context the navigation laboratory at ESA's European Space Research and Technology Centre (ESTEC), in the Netherlands, could be considered relevant in the receivers validation procedures, as well as in the Signal-In-Space (SIS) experimentation activity, where the GSTB-v2 Experimental Test Receiver (GETR) plays a key role. The paper will provide the overview of the set-up available in the navigation laboratory at ESTEC, describing the equipments composing the test bench. The Galileo Signal Validation Facility (GSVF-v2) will be presented pointing out the capabilities in the Galileo-like signal generation. In particular, the Galileo L1 Open Service (OS) signal will be analyzed, and the corresponding GETR tracking performance will be presented in terms of code tracking noise curves, autocorrelation function and multipath envelope. Tracking performance for the Galileo L1 OS signal in multipath environments will be evaluated in terms of static and dynamic contributions. Finally, some screenshots of the GETR graphical user interface (while tracking GIOVE-A signals) will also be included in the paper, as the prove that the entire set-up has been fully integrated with the Space Engineering's Galileo antenna for the reception and process of live GIOVE-A signals. [ABSTRACT FROM AUTHOR]

Satellite-based navigation systems uses one-way ranging measurements for system orbit estimation and time-keeping, due to its operational advantage when compared with two-way ranging technique, in terms of complexity of ground monitoring stations (completely passive and requiring a simple omnidirectional antenna to track all the satellites in view). However, a sufficient number of simultaneous independent measurements is required to solve the system unknowns: in particular simultaneous visibility of multiple stations by an individual satellite (allowing to separate the ground stations clocks contributions since the SVs clocks disappear), as well as simultaneity of observations from the same monitor stations of a large number of satellites (allowing to recover the SVs clocks parameters, since the GSS clocks drop out) is the key to an effective separation in the solution of the clock contributions from the pseudo-ranges. In the Galileo IOV phase (consisting of 4 satellites on two orbital planes and a ground network of 20 Sensor Stations), the first condition is clearly fulfilled, however the second condition is not met for a considerable part of the time. If two GSSs do not see simultaneously a single Galileo satellite, they will not be able to estimate their clocks time and frequency drifts, i.e. they will not be synchronized. The free running clocks will essentially enter a holdover mode, were the relative time between the two stations will be slowly drifting as a function of the initial conditions and the stability of the clocks. The ground stations synchronization will gradually degrade with time and when a satellite will rise on the horizon they will be essentially not synchronized to the extent required to carry on a one-way-based Orbit Determination & Time Synchronization (OD&TS). During the IOV phase, the limited number of satellites available and the peculiar characteristics of the Galileo orbits will make difficult for the Orbit Determination and Time Synchronization to start producing meaningful data, therefore some form of intermediate operational configuration must be sought to help in the OD&TS process initialization. The paper will address the proposed solution to overcome the problem of Galileo system initialization starting from the intermediate configuration with first 2 satellites (first IOV Launch) up to final IOV Configuration after second IOV launch. The proposed solution will be based on a limited use of GPS to insure the synchronization of the Galileo Sensor Stations, relying on the exploitation of the Linked Common View Time Transfer (LCVTT) Technique, while the Galileo Orbit Determination and SVs clocks characterization will be carried on autonomously and independently by GPS, in a two step process, up to the achievement of the IOV Configuration with 4 satellites, when the nominal Orbit Determination and Time Synchronization process will be operated. Moreover the paper will address the development of the LCVTT Algorithm, carried on as part of development of the infrastructure aiming to support the Galileo Verification Phase currently under definition as part of Galileo Phase C/D/E1 contract. The algorithm design and implementation will be presented together with the validation carried out (both for LCVTT and MLCVTT) to verify that the synchronization accuracy is adequate to support the Galileo System Initialization. [ABSTRACT FROM AUTHOR]