Search

This paper presents a novel application of a semantic annotation system, named Cerno, to analyze research publications in electronic format. Specifically, we address the problem of providing automatic support for authors who need to deal with large volumes of research documents. To this end, we have developed Biblio, a user-friendly tool based on Cerno. The tool directs the user's attention to the most important elements of the papers and provides assistance by generating automatically a list of references and an annotated bibliography given a collection of published research articles. The tool performance has been evaluated on a set of papers and preliminary evaluation results are promising. The backend of Biblio uses a standard relational database to store the results. [ABSTRACT FROM AUTHOR]

The aim of this paper is to explore new metaphors for interaction design on tabletop system. Tabletop systems are shared horizontal surface for co-located collaboration, which leads to original problems when designing interactions. We propose two metaphors based on the paper: the peeling metaphor, and the slot metaphor, and then suggest a way of using them to design new interactions for solving some of the problems of tabletop systems: documents organization, documents transmission and documents duplication. [ABSTRACT FROM AUTHOR]

In this tutorial paper we summarise the key features of the multi-threaded Qu-Prolog language for implementing multi-threaded communicating agent applications. Internal threads of an agent communicate using the shared dynamic database used as a generalisation of Linda tuple store. Threads in different agents, perhaps on different hosts, communicate using either a thread-to-thread store and forward communication system, or by a publish and subscribe mechanism in which messages are routed to their destinations based on content test subscriptions. We illustrate the features using an auction house application. This is fully distributed with multiple auctioneers and bidders which participate in simultaneous auctions. The application makes essential use of the three forms of inter-thread communication of Qu-Prolog. The agent bidding behaviour is specified graphically as a finite state automaton and its implementation is essentially the execution of its state transition function. The paper assumes familiarity with Prolog and the basic concepts of multi-agent systems. [ABSTRACT FROM AUTHOR]

This paper is a tutorial describing the main features of the KGP (Knowledge-Goals-Plan) model of agency and giving user guidance on how the model can be used to develop applications. The KGP model is based on computational logic. It consists of an abstract component, a computational component and an implementation. This paper concentrates on the abstract component, which consists of formal specifications of a number of different modules, including the knowledge bases, capabilities, transitions and control. For each of these we summarise what is provided by the model, and through the platform implementing the model, and what is left to the users to specify according to the requirements of the applications for which they wish to use the KGP model to design agents. [ABSTRACT FROM AUTHOR]

Many design activities depend on communicative activities around collaboratively produced prototypes. A common communication practice in producing text documents is to add annotation in the form of comments. Previous research indicates that electronic paper-prototyping can be used to rapidly create simple prototypes of interactive systems, such as websites. Little is known, however, about how to provide and maintain variety of communication channels around such electronic paper-prototypes to enable end-users and other stakeholders to contribute to design dialogues. This paper presents Gabbeh, an electronic paper-prototyping tool, and reports on an evaluation using the tool in a simulated design exercise. [ABSTRACT FROM AUTHOR]

Wet paper codes were proposed as a tool for constructing steganographic schemes with an arbitrary selection channel that is not shared between the sender and the recipient. In this paper, we describe new approaches to wet paper codes that enjoy low computational complexity and improved embedding efficiency (number of message bits per embedding change). Some applications of wet paper codes to steganography and data embedding in binary images are discussed. [ABSTRACT FROM AUTHOR]

This article proposes a Memetic Differential Evolution (MDE) for designing digital filters which aim at detecting defects of the paper produced during an industrial process. The MDE is an adaptive evolutionary algorithm which combines the powerful explorative features of Differential Evolution (DE) with the exploitative features of two local searchers. The local searchers are adaptively activated by means of a novel control parameter which measures fitness diversity within the population. Numerical results show that the DE framework is efficient for the class of problems under study and employment of exploitative local searchers is helpful in supporting the DE explorative mechanism in avoiding stagnation and thus detecting solutions having a high performance. [ABSTRACT FROM AUTHOR]

U-Healthcare promises increases in efficiency, accuracy and availability of medical treatment; however it also introduces the potential for serious abuses including major privacy violations, staff discrimination and even life-threatening attacks. In this position paper we highlight some potential threats and open the discussion about the security requirements of this new scenario. We take a few initial steps towards a U-Healthcare security policy and propose a system architecture designed to help enforce the policy's goals. [ABSTRACT FROM AUTHOR]

Global paper industry needs systems that can be used in all locations. International user studies can be helpful when integrating systems. Not only due to the lack of common language but also the differences in culture and the usage of systems, information from different countries needs to be collected and analyzed so that the integration development is not be biased and unilateral. During the study some food for thought was gathered on what to consider when planning an international user study. [ABSTRACT FROM AUTHOR]

With the increased use of Internet and information technology all over the world, there is an increased amount of criminal activities that involve computing and digital data. These digital crimes (e-crimes) impose new challenges on prevention, detection, investigation, and prosecution of the corresponding offences. Computer forensics (also known as cyberforensics) is an emerging research area that applies computer investigation and analysis techniques to help detection of these crimes and gathering of digital evidence suitable for presentation in courts. This new area combines the knowledge of information technology, forensics science, and law and gives rise to a number of interesting and challenging problems related to computer security and cryptography that are yet to be solved. In this paper, we present and discuss some of these problems together with two successful cases of computer forensics technology developed in Hong Kong that enable the law enforcement departments to detect and investigate digital crimes more efficiently and effectively. We believe that computer forensics research is an important area in applying security and computer knowledge to build a better society. [ABSTRACT FROM AUTHOR]

This paper is concerned with a multi-resolution tool for analysis of a time series aiming to detect abnormalities in various frequency regions. The task is treated as a kernel based novelty detection applied to a multi-level time series representation obtained from the discrete wavelet transform. Having a priori knowledge that the abnormalities manifest themselves in several frequency regions, a committee of detectors utilizing data dependent aggregation weights is build by combining outputs of detectors operating in those regions. [ABSTRACT FROM AUTHOR]

Amongst several fundamental aspects in multi-agent systems design, the definition of the agent interaction space is of the utmost importance. The specification of the agent interaction has several facets: syntax, semantics, and compliance verification. In an open society, heterogenous agents can participate without showing any credentials. Accessing their internals or their knowledge bases is typically impossible, thus it is impossible to prove a priori that agents will indeed behave according to the society rules. Within the SOCS (Societies Of ComputeeS) project, a language based on abductive semantics has been proposed as a mean to define interactions in open societies. The proposed language allows the designer to define open, extensible and not over-constrained protocols. Beside the definition language, a software tool has been developed with the purpose of verifying at execution time if the agents behave correctly with respect to the defined protocols. This paper provides a tutorial overview of the theory and of the tools the SOCS project provided to design, define and test agent interaction protocols. [ABSTRACT FROM AUTHOR]

This paper is based on the tutorial given as part of the tutorial programme of CLIMA-VI. The tutorial aimed at giving an overview of the various features available in Jason, a multi-agent systems development platform that is based on an interpreter for an extended version of AgentSpeak. The BDI architecture is the best known and most studied architecture for cognitive agents, and AgentSpeak is an elegant, logic-based programming language inspired by the BDI architecture. [ABSTRACT FROM AUTHOR]

One of the simplest protocols for clock synchronization in wireless ad hoc and sensor networks is the converge-to-max protocol, which has the simple logic of adjusting each node's clock to be at least as large as any neighbor's. This paper examines the converge-to-max protocol, showing it to be stabilizing even when node clocks have skew, bounded domains, and dynamic communication links. [ABSTRACT FROM AUTHOR]

We developed AirTransNote, a computer-mediated classroom collaboration system. The system enables real-time note-sharing. AirTransNote manages notes written by students on paper and enables the teacher to browse through the notes or show them to the students. AirTransNote can analyze students' answers, helping the teacher better understand their problems. The system is not meant to provide an alternative to the conventional way of instruction; rather, it is designed to enhance class interaction. We conducted a preliminary study using questionnaires and found that this system can be feasible to apply for classroom environment. [ABSTRACT FROM AUTHOR]

In this article I will present an overview of a selection of tools for execution and proof based on temporal logic, and outline both the general techniques used and problems encountered in implementing them. This selection is quite subjective, mainly concerning work that has involved researchers I have collaborated with at Liverpool (and, previously, Manchester). The tools considered will mainly be theorem-provers and (logic-based) agent programming languages. Specifically: - clausal temporal resolution [21, 28] and several of its implementations, namely , and , together with its application to verification [35]; - executable temporal logics [24, 4] and its implementation as both MetateM [3] and Concurrent MetateM [22, 49], together with its use as a programming language for both individual agents [23, 26, 29] and multi-agent systems [33, 30, 32]. In addition, I will briefly mention work on induction-based temporal proof [5], temporal logic programming [1], and model checking [7]. Rather than providing detailed algorithms, this presentation will concentrate on general principles, outlining current problems and future possibilities. The aim here is to give the reader an overview of the ways we handle temporal logics. In particular how we use such logics as the basis for both programming and verification. [ABSTRACT FROM AUTHOR]

Building and evolving grid applications is complex. A promising approach to managing this complexity is component-based development, currently attracting growing interest in the grid community. Evaluating the effectiveness of component-based development requires real-world experience. To this end, this paper presents a case study in reengineering a high performance numerical solver to become a component-based grid application. The adopted component model is an extension of the generic Fractal model that specifically targets grid environments. The paper provides qualitative and quantitative evidence that componentisation has improved the modifiability and reusability of the application without significantly affecting performance. [ABSTRACT FROM AUTHOR]

There is an on-going trend towards turning paper documents that store personal information or other valuable data into machine-readable form. An example of this trend is the electronic passport that will become common in the near future. In this paper we show how the security of these machine readable documents could be improved by combining RFID with optical memory devices. We propose integrating an optical memory device into the RFID enabled smart document and present methods how these two storage media can be combined to secure the document against threats like illicit scanning, eavesdropping and forgery. The presented approaches make use of the optical document-to-reader channel which is more secure than the radio-frequency communication interface. To demonstrate the potential of our approaches we show how they could overcomea number of existing security and privacy threats of electronic passports. [ABSTRACT FROM AUTHOR]

RFID systems, and indeed other forms of wireless technologies, are now a pervasive form of computing. In the context of security and privacy, the most threatening (to privacy) and vulnerable (to insecurity) are the ‘low cost RFID systems'. The problems are further aggravated by the fact that it is this form of RFID that is set to proliferate through various consumer goods supply chains throughout the world. This is occurring through the actions of multinational companies like Wal-Mart, Tesco, Metro UPS and of powerful government organizations such as the United States DOD (Department Of Defence) and FDA (Food and Drug Administration). This paper examines the vulnerabilities of current low cost RFID systems and explores the security and privacy threats posed as a result of those vulnerabilities. The paper will also formulate a framework for defining the problem space constructed around low cost RFID systems, and consider the challenges faced in engineering solutions to overcome the defencelessness of low cost RFID systems. Security issues beyond and including interrogators will not be considered as such concerns may be easily resolved using existing technology and knowledge, and because interrogators are powerful devices where complex encryption and decryption operations may be performed using either the embedded systems, DSPs, or using hardware implementation of encryption engines on a FPGA device onboard a reader. [ABSTRACT FROM AUTHOR]

This paper presents an overview of modern cryptography. As the title of this paper suggests this paper is a primer, and provides background information that can assist other researchers in further study, and in developing security mechanisms suitable for inclusion on RFID tags. [ABSTRACT FROM AUTHOR]

Copyright of Insider Attack & Cyber Security is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we propose a searching service optimized for highly dynamic mobile ad-hoc networks based on a flooding approach. MANETs unreliability and routing costs prevent the use of central servers or global infra-structured services on top of a priori defined virtual overlay networks. A flooding approach over a virtual overlay network created on-demand performs better. Flooding is supported by a light-weight clustering algorithm. The paper compares the relative efficiency of two clustering approaches using 1.5-hop and 2.5-hop neighborhood information, and of a non-clustered approach. It presents a set of simulation results on the clustering efficiency and on searching efficiency for low and high mobility patterns, showing that the 1.5-hop algorithm is more resilient to load and to node movement than the 2.5-hop algorithm. [ABSTRACT FROM AUTHOR]

This paper examines, via simulation, the performance of an 802.11e MAC over an 802.11g PHY operating in DSSS-OFDM mode. The DSSS-OFDM scheme provides data rates of up to 54Mb/s as well as interoperability with 802.11b nodes. Due to the widespread use of 802.11b nodes, such interoperability is an important consideration. This paper involves a study of the number of simultaneous bidirectional G.711 VoIP calls that can be supported by such a WLAN. The results show that this mode of operation introduces a very significant overhead. The actual number of calls that can be carried is limited to 12 when using the 24Mb/s data rate and 13 when using either the 36Mb/s or 54Mb/s rates. These results demonstrate the well-known disparity between uplink and downlink performance, with the downlink imposing the limit on the number of calls that can be carried by the system in the cases studied. The results also show that when when a significant amount of lower priority traffic is introduced into the system, it can have a significant impact on VoIP call capacity despite the use of 802.11e. [ABSTRACT FROM AUTHOR]

In the next generation Internet protocol (IPv6), mobility is supported by means of Mobile IPv6 (MIPv6). As a default part of the MIPv6 protocol, route optimization is used to route packets directly to a mobile node's currently used address at the mobile node's visited subnet. Return Routability is the protocol suggested by the IETF for managing this task. Route optimization is often carried out during handovers, where a mobile node changes network attachment from one subnet to another. To offer seamless handovers to the user it is important that route optimizations are carried out quickly. In this paper we will present an attack that was discovered during design of a new and more seamless protocol than the Return Routability. Our improved route optimization protocol for Mobile IPv6 suffers this attack; therefore we wanted to investigate if a similar attack was feasible on the Return Routability protocol. In this paper, we show that our new route optimization protocol offers no less security than the already standardized Return Routability protocol in this field. [ABSTRACT FROM AUTHOR]

The Host Identity Protocol (HIP) is one of the more recent designs that challenge the current Internet architecture. The main features of HIP are security and the identifier-locator split, which solves the problem of overloading the IP address with two separate tasks. This paper studies the possibility of providing HIP services to legacy hosts via a HIP proxy. Making a host HIP enabled requires that the IP-stack of the host is updated to support HIP. From a network administrator's perspective this can be a large obstacle. However, by providing HIP from a centralized point, a HIP proxy, the transition to begin using HIP can be made smoother. This and other arguments for a HIP proxy will be presented in this paper along with an analysis of a prototype HIP proxy and its performance. [ABSTRACT FROM AUTHOR]

This paper provides an in-depth analysis of selected important topics related to the quality assessment of e-commerce systems. It briefly introduces to the reader a quality assessment model based on Bayesian Networks and presents in detail the practical application of this model, highlighting practical issues related to the involvement of human subjects, conflict resolution, and calibration of the measurement instruments. Furthermore, the paper presents the application process of the model for the quality assessment of various e-commerce systems; it also discusses in detail how particular features (data) of the assessed e-commerce systems can be identified and, using the described automated assessment process, lead to higher abstraction information (desiderata) regarding the quality of the assessed e-commerce systems. [ABSTRACT FROM AUTHOR]

In this paper we present a packet detection technique developed in the context of a Italian national research project aiming at developing the "Enabling blocks for the integration in CMOS technology of a Multi-Band OFDM transceiver," adhering to the recent ECMA 368 standard. The paper deals with the digital section of the receiver, and specifically with the identification of a low complexity packet detection technique. The chosen approach is a correlation receiver followed by a threshold comparison. Its performance is tested in a realistic scenario taking into account channel dispersion and receiver inaccuracies. [ABSTRACT FROM AUTHOR]

In general, a wireless sensor network consists of a large number of lowcost, static nodes that organize themselves in order to deliver events notification to a sink node in a multi-hop fashion. Typically, nodes are battery driven and are limited in terms of processing, storing and communication capabilities. On the contrary, an autonomous mobile robot is an expensive object, equipped with advanced interfaces and capable of performing complex tasks. The complementary capabilities of these two technologies can be integrated in a synergetic manner not only to enhance the performance of each single system, but also to create novel applications and services. In this paper, we will describe the RAMSES2 project, which aims at investigating the potential benefits resulting from the integration of WSNs and AMRs. As case study, we present and analyze the first experimental results concerning the selflocalization problem, by which a wireless sensor node, placed in an unknown location, infers its own position by processing the information received by an AMR that moves in its proximity, thus acting as mobile beacon. The advantage of using mobile beacons for localization in WSN has been already reported in literature. However, most of the previous work refers to outdoor scenarios, while in this paper we report results obtained in a typical indoor environment. The localization problem in indoor environment represents a challenging benchmark to check the functionalities of the RAMSES2 hybrid platform and, despite the project is still in a very initial stage, the first results are promising and call for further investigation of this novel and interesting domain. [ABSTRACT FROM AUTHOR]

The availability of a wide range of cheap single chip computers, and of integrated radio-transceivers operating in the ISM band, has significantly encouraged the design and deployment of efficient wireless sensor networks (WSNs). This paper presents the original design and implementation of a multi-hop WSN, based on a Microchip MCU and a Cypress RF device, able to publish the data gathered from the field through the facilities offered by SNMP agents. The algorithm adopted to manage the network is discussed, and a possible application scenario is illustrated. A working prototype based on the hardware platform, software and protocol described in this paper has been deployed and tested, and some of the obtained results are shown. [ABSTRACT FROM AUTHOR]

An evaluation of Quality-of-Service (QoS) measures in mobility management for interworked Next Generation Mobile Data Networks (NGMNs) is presented in this paper. The interworking framework used for the QoS analysis is a novel approach for NGMNs. This enables multiple cellular networking technologies such as the Universal Mobile Telecommunications System (UMTS) and CDMA2000 technology to interwork with Wireless Local Area Networks (WLANs) under a common platform. The proposed framework exploits the IP Multimedia Subsystem (IMS) as a universal coupling mediator for real-time session negotiation and management and Mobile IP (MIP) for IP mobility management. The latter part of the paper uses an analytical model for analyzing the QoS measures related to mobility management and uses an OPNET based model for verification. [ABSTRACT FROM AUTHOR]

Wireless Mesh Networks (WMNs) are increasingly proposed as an economic and effective solution to easily delivering a large variety of services anytime anywhere. However, wireless communications suffer from some shortcomings which limit the use of real-time applications, especially VoIP applications. In fact, the effective available bandwidth can be, sometimes, too low to accept new calls, in addition to the ongoing ones, without the call quality becoming unacceptable. Moreover large delay variations and packet loss dramatically affect speech quality and speakers interactivity. This paper refers to a wireless mesh network scenario used to provide VoIP services to a group of buildings. Application of Automatic Repeat-reQuest (ARQ) to reduce losses due to the wireless link however causes high variability on the output transmission rate of the buffer in the multiplexer located in each building. So, to avoid buffer congestion, in this paper we propose an architecture where VoIP sources use Adaptive MultiRate encoder (AMR), in such a way that they can be controlled according to the state of the buffer queue in the multiplexer. To this end a new rate controller scheme is defined, and its performance is evaluated in order to achieve some hint to design its parameters. [ABSTRACT FROM AUTHOR]

Wireless technology evolution permits users to be always connected to IP-based services through IP-based devices. Furthermore, thanks to wireless technology progresses, wirelessly connected users may now exploit a bandwidth comparable to the one provided by copper-based access technologies (e.g., xDSL). WiMAX (i.e., IEEE 802.16) is one of the wireless technologies with such potential. This paper addresses IEEE 802.16 aspects, from the enhanced modes of operations to the wireless/wired MAN integration. In particular, the paper focuses on advanced physical layer technologies for wireless transmission such as Multiple Input Multiple Output (MIMO) antennas and Adaptive Modulation and Coding (AMC), the optional IEEE 802.16 Mesh mode of operation, and the integration of wireless and wired/optical Metropolitan Area Networks (MANs). Current status and issues are presented and solutions are proposed. [ABSTRACT FROM AUTHOR]

In this paper the issue of energy efficiency in CDMA wireless data networks is addressed through a game theoretic approach. Building on a recent paper by the first two authors, wherein a non-cooperative game for spreading-code optimization, power control, and receiver design has been proposed to maximize the ratio of data throughput to transmit power for each active user, a stochastic algorithm is here described to perform adaptive implementation of the said noncooperative game. The proposed solution is based on a combination of RLS-type and LMS-type adaptations, and makes use of readily available measurements. Simulation results show that its performance approaches with satisfactory accuracy that of the non-adaptive game, which requires a much larger amount of prior information. [ABSTRACT FROM AUTHOR]

This paper will consider how Common Criteria evolved, how it is defined and how it is used in practice. As an example we will look at how Common Criteria is applied to smart card evaluations. This paper will not attempt to define in detail Common Criteria, nor should the reader expect to understand it in sufficient detail to be able to immediately participate in evaluations. It will, however, give a gentle introduction to what is a complex and demanding evaluation methodology. [ABSTRACT FROM AUTHOR]

Copyright of Signal Processing for Image Enhancement & Multimedia Processing is the property of Springer eBooks and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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]

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]

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]

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]

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]

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]

This paper is about the impact of the Galileo signal in space on the Acquisition system of a GNSS receiver. The Galileo signal definition presents features allowing improvements of the acquisition and tracking performance, but these differences with respect to GPS must be taken into account in the receiver design phase. In this paper the classical acquisition blocks designed for GPS will be revisited, from a statistical point of view and in terms of performance, looking to the issues that longer codes, BOC modulations and pilot channels will introduce on the Galileo Open Service (OS). [ABSTRACT FROM AUTHOR]

The paper aims at introducing the on-going activities around the design and development of a network-based positioning system exploiting the advantages of both the European Geostationary Navigation Overlay System (EGNOS) and the VHF communication infrastructure with the goal to support the Alpine Rescue Teams in the management of search and rescue operations. Such an innovative integration strategy among analog communication channels and EGNOS is the key topic of a project named Precise Operation Positioning for Alpine Rescue Teams (POP-ART) co-funded by the Galileo Joint Undertaking as specific action toward the support of innovative ideas around EGNOS and Galileo proposed by Small Medium Enterprises (SME). The positioning system is based on the raw GPS measurements collected by the users and transmitted to a Local Element by VHF radio channels (or GPRS when available). The POP-ART activities are based on pre-existing works already presented in [1] [3]. The goal of the paper is to provide the latest information on the results already achieved within the project as well as the perspective on the expected performance thanks to several analyses on the EGNOS features. In particular, the results demonstrate that the system fully exploits the improvement given by the EGNOS signals, ensuring a suitable level of accuracy in the positioning for a larger time with respect to standalone GPS positioning. [ABSTRACT FROM AUTHOR]

The paper focuses on the emerging space-distributed multisatellite constellations, swarms and formations, which are increasingly proposed to carry out Missions demanding tremendous intersatellite information exchange rates, thus justifying the use of optical frequencies. The paper then addresses the critical issue of how to cope with the fast initial satellite acquisition needs, considering that the satellites will increasingly be injected in orbits leading to time-variable topologies, and that communication needs increasingly require minimizing link acquisition and reacquisition times during satellites handover. Solutions based on the partial use of the GPS data available on board the satellites and broadcast to all others are described. The mix of large and powerful satellites and of less capable microsatellites demands solutions which are tailored to the planned capabilities or even capable of complementing them. [ABSTRACT FROM AUTHOR]

Enterprises are looking at Grid computing as a technology of enormous potential. However, there are several issues which require immediate attention before Grid can become an important component of the IT infrastructure. One such issue is migration of legacy applications to the Grid environment. In such cases, it becomes imperative to understand whether the application performance would significantly improve on migration. In this paper an attempt is made to provide a systematic framework called the Grid Application Migration Framework (GAMF) for handling the migration process. The framework consists of Grid Code Analyzer (GCA), an independently deployable component which generates a Directed Acyclic Graph (DAG). The paper also proposes a DAG reducer algorithm for reducing the DAG. The framework is tested with several proprietary and open source C as well as Java codes. In the paper, we take three sample open source applications and demonstrate the usefulness of the framework. Finally, a small sample is analyzed and recoded to show that validity of the proposed mechanisms. [ABSTRACT FROM AUTHOR]

This paper presents a case study in the generic design of Grid component models. It defines a framework allowing two component systems, one running in a CCA environment, and another running in a Fractal environment, to interact as if they were elements of the same system. This work demonstrates the openness of both Fractal and CCA component models. It also gives a very generic and exhaustive overview of the interaction strategies that can be adopted to allow full integration of these two models, like strategies for reusing in Fractal single components from the CCA world and connecting a Fractal system to an already running CCA assembly. Finally, it presents the implementation and results of investigation of interoperability between two given component frameworks: MOCCA and ProActive. In generall, this paper presents the key concepts useful to make any two component models interoperate. [ABSTRACT FROM AUTHOR]