About
58
Publications
32,226
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,246
Citations
Introduction
Publications
Publications (58)
Internet of Things platforms for Smart Cities are technologically complex and deploying them at large scale involves high costs and risks. Therefore, pilot schemes that allow validating proof of concepts, experimenting with different technologies and services, and fine-tuning them before migrating them to actual scenarios, are especially important...
Multiparty networked applications, which are gaining interest in areas as diverse as online games, e-learning, e-health, and collaborative work, tend to depend on a set of common functions. In conventional IP networks, these shared functions require application-specific servers, leading to scale diseconomies and complicating interoperability. The I...
HSPA (High Speed Packet Access) technologies have become an attractive solution for broadband wireless Internet access. This article evaluates the quality of service experimented by one HSPA user in the presence of multiple terminals sharing the cell capacity. The study focuses on Web traffic and includes analytical and simulation results, providin...
IP Multimedia Subsystem (IMS) is a platform for service provisioning over IP networks, standardized by 3GPP. One of the key concepts of this technology is service enablers. Enablers are reusable modules encapsulating certain network functions, in order to simplify the development of new network services. In this paper, we present GroupManager, an e...
A quick and efficient reaction to an attack is important to address the evolution of security incidents in current communication networks. The ReD (Reaction after Detection) project’s aim is to design solutions that enhance the detection/reaction security process. This will improve the overall resilience of IP networks to attacks, helping telecommu...
The IP Multimedia Subsystem (IMS) brings more functionality into communication networks and allows them to offer a range of services beyond the mere transport of media. IMS standard multiparty services include audiovisual conferencing and Push To Talk (PTT/PoC), which are powered by specific (and expensive) servers performing media handling functio...
En el libro se analizan con detalle las principales tecnologías de acceso de banda ancha, considerando tanto sus características técnicas de prestaciones y escalabilidad, como su adecuación para prestar servicios de telecomunicación. Además, se estudian las aproximaciones actuales hacia la convergencia de redes, en un contexto en el que los operado...
The Internet and computer networks are exposed to an increasing number of security threats. With new types of attacks appearing continually, developing flexible and adaptive security oriented approaches is a severe challenge. In this context, anomaly-based network intrusion detection techniques are a valuable technology to protect target systems an...
Multimedia multiparty applications on the Internet are commonly supported by specific servers containing all the required functionalities in a centralized manner. The IP Multimedia Subsystem (IMS) is the current paradigm of the Next Generation Network (NGN) model. It provides a set of basic service enablers and functions beyond IP connectivity, suc...
To address the evolution of security incidents in current communication networks it is important to react quickly and efficiently to an attack. The RED (Reaction after Detection) project is defining and designing solutions to enhance the detection/reaction process, improving the overall resilience of IP networks to attacks and help telecommunicatio...
Next-generation network architectures aim at the convergence of services (e.g. telephony, television, Web access, online games,
and new services) over a common IP core. Additionally, the integration of wired and wireless access technologies will offer
users ubiquitous access to all those services. Telecommunications networks rely on signalling prot...
High-Speed Downlink Packet Access (HSDPA) is being introduced by mobile operators as a solution both for increasing the downlink throughput and for achieving a more efficient usage of the radio resources. This work analyses the quality of experience of HSDPA users, based on experiments and measurements over a commercial network. The effect of multi...
A quick and efficient reaction to an attack is important to address the evolution of security incidents in current communication networks. The ReD (Reaction after Detection) project's aim is to design solutions that enhance the detection/reaction security process. This will improve the overall resilience of IP networks to attacks, helping telecommu...
The deployment of broadband networks and the growth of the number of connected users have caused the prolifera- tion of new highly interactive multimedia multiuser appli- cations (HIMMA). Networked games constitute one of the paradigms of HIMMA applications, specially thanks to the so called next generation gaming platforms, which inte- grate not o...
Multiprotocol Label Switching (MPLS) offers a simple and flexible transport solution for multiservice networks, and many operators are currently using or considering the use of an MPLS backbone. In UMTS networks, MPLS can be used both in the access part (i.e. the links that provide connectivity to each base station) and in the core. However, the ef...
The access transport infrastructure of a cellular communications network represents a significant proportion of the total network cost. This prevents the network designer from over-dimensioning these links. In the case of UMTS (universal mobile telecommunications system) access network, the use of a packet-switched technology (ATM for the first Rel...
Multiprotocol Label Switching (MPLS) is emerging as a flexible technology that can transport voice, IPv4, IPv6, layer 2 services (Frame Relay, ATM, Ethernet, etc.), and even PDH and SDH/SONET circuits over a single packet infrastructure, in a new attempt to solve the old problem of network convergence. MPLS traffic engineering, quality of service s...
This paper presents several experiences and conclusions about the usage of the J2EE middleware platform in an e-commerce mediation framework, and introduces mobile agent possibilities within the same environment. The main conclusions are taken from the Smart-EC project, where J2EE and mobility are considered as a value added in its architecture. Ot...
Multiprotocol Label Switching (MPLS) offers a simple and flexible transport solution for multiservice networks. Therefore, many UMTS operators are currently considering the use of a MPLS backbone. However, the efficient transport of short voice and data packets in the UMTS access network requires multiplexing and segmentation functions not provided...
This article focuses on the dimensioning of the UMTS (Universal Mobile Telecommunications System) access network infrastructure. The current UMTS specifications define a protocol architecture for the access network terrestrial interfaces based on ATM (Asynchronous Transfer Mode). In this context, the main objective of our work is to determine the o...
After a delay of some years, third generation mobile communication systems are beginning to be deployed. Thus, most European countries are currently involved in the installation of commercial UMTS networks based on the Release 99 set of specifications of the 3GPP 1 . The main novelty of these first UMTS networks lies on the access segment, includin...
The efficient support of multiple traffic classes with different quality of service requirements (end-to-end delay, jitter,
loss) poses an extraordinary complexity in the design of third-generation mobile networks. This task becomes especially critical
for the access network, where radio and transmission resources are usually scarce. In this paper...
This paper describes the realization of a business-to-business inter- mediation e-commerce platform. The main concern derives from the usage of two emerging technologies, namely the Java 2 Enterprise Edition (J2EE) and the Mobile Agent Technology (MAT). The key issues that are addressed in this paper are the following. First, the scenario of the pr...
Resumen El soporte eficiente de múltiples clases de tráfico con diferentes requisitos de calidad de servicio plantea nuevos problemas de ingeniería a la hora de diseñar una red de comunicaciones móviles de tercera generación (3G). El problema es más crítico en el caso de la red de acceso, donde habitualmente los recursos radio y de transmisión suel...
The support of multiple traffic classes with different Quality of Service (QoS) requirements poses new challenges in the field of network design. This is also true in the case of third generation (3G) mobile communications systems, especially in the access network, where radio and transmission resources are usually scarce. In this paper we approach...
Supporting multiple traffic classes with different QoS (quality of service) constraints in third generation mobile systems is not a straightforward problem. This issue becomes critical at the access network interfaces, where transmission resources are usually expensive. One of the most important interfaces is the one that connects each base station...
This paper describes a brokering platform for the provision of complex services over the Internet. The platform is able to analyse a request for a complex service, divide it into simple components, and combine several services and products, offered by different providers, into a solution that satisfies the complex request. The platform helps the us...
This paper describes a brokering platform for the provision of complex services over the Internet. The platform is able to analyse a request for a complex service, divide it into simple components, and combine several services and products, offered by different providers, into a solution that satisfies the complex request. The platform helps the us...
Protocol conformance testing provides a extremely valuable mechanism in order to reduce incompatibility risks when interconnecting equipment from different manufacturers. This is achieved by defining a common set of test cases that an implementation must pass to be considered compliant with a particular standard. The benefits of the conformance tes...
We analyse the feasibility of using a building management system
(BMS) with multimedia communications over an automation network,
focusing our attention on the requirements and limitations for digital
video transmission. First, we address the communications requirements of
BMS video information, selecting a quarter of intermediate format
(QCIF). We...
We give ideas that contribute to a clear description,
specification and modelling of some communication protocols for
distributed communication systems based on industrial LANs. In these
systems problems turn up with time management, coexistence of different
intelligent devices that work in real time, compatibility of synchronous
and asynchronous o...
This paper proposes a voice-data integrated digital network
designed for Micro-VSAT networks. The design is the result of a study
performed under contract for the European Space Agency, in the framework
of the development of a portable VSAT network based on the advanced
access technique Bandlimited Quasi-Synchronous CDMA, operating in
Ku-band (refe...
The paper presents the results of a simulation study, performed
under contract for the European Space Agency (ESA), which evaluated the
performance of the layer 2 signalling protocol in the ESA On-Board
Processing Network (OBP). Two layer 2 design options were compared in
the study: a general protocol based on the HDLC family, and a simplified
prot...
This paper studies the provision of low data rate services in
micro-VSAT networks such as the bandlimited quasisynchronous CDMA VSAT
system currently being developed by ESA. It presents the results of a
simulation study intended to evaluate the performance impact of several
system design choices. The simulated network (which is a generalization
of...
This paper reports the validation and performance analysis of a
Q.931 signalling software, which was developed in the frame of the
project Factory Customer Premises Network (FCPN, Esprit P2198). In FCPN,
a top-down stepwise refinement approach was used, supported by the LOTOS
formal description technique. This approach was based on a sequence of
de...
This paper describes the application of the standard formal
description technique Estelle to the modelling and specification of the
manufacturing automation protocol three-layer architecture (real-time
MAP). The paper discusses the real-time requirements that must be met by
communication protocols operating in manufacturing plants, and shows how
th...
This paper describes the application of the Formal Description Technique ESTELLE to the modelling and design of Operating Systems. We describe the overall scheme of a multiprogramming operating system and then we design in a top-down way the operating system, proposing its specification in ESTELLE at the same time.
The use of ESTELLE allows not onl...
This paper describes the formal specification, testing, and implementation of the D-channel layer 3 signalling protocol used in the user-network interface of the Integrated Services Digital Network. This protocol is informally defined in the CCITT Recommendation Q.931. The Formal Description Technique LOTOS has been used to formalize a subset of th...
In an ATM-based network it is foreseen that connectionless traffic will be handled by Connectionless Servers (CLSs) interconnected to each other and to the users via semi-permanent connections, forming a Connectionless Overlay Network. This paper discusses the necessity of frame-level buffering in the CLSs in order to meet the connectionless servic...
A graphical tool is presented for the analysis and simulation of
communication networks. The tool provides a user interface based on
windows, icons, and command menus that allows users to define the
network topology and attributes easily. Application programs that
simulate or analyze some network aspect, interact with the tool through
a program int...
A description is presented of the formal specification and
implementation of the D-channel layer-3 protocol used in the
user-network interface of the integrated services digital network. This
protocol is informally defined in the CCITT Recommendation Q.931. The
formal description technique LOTOS has been used to formalize this
definition and to der...
This paper describes a performance simulation tool based on Estelle. Estelle is a Formal Description Technique designed to specify the behavior of concurrent systems, in particular communication protocols. It is based on a state machine model extended with Pascal-like data structures and statements. Currently, Estelle is an International Standard o...
An effort is made to analyze the admission delay of an X.25 connection, modeling the virtual circuit as an equivalent server with parameters related to the behaviour measurable by the X.25 user. The authors review M. Reiser's (1978) mean value analysis of a virtual circuit with window flow control, Norton's theorem is used to obtain an equivalent s...
The authors present the results of research intended to assess the
effect of several transport mechanisms on throughput observed between
two transport users communicating over concatenated X.25 networks. A set
of simulated and live experiments are used to investigate transport
performance over X.25 networks. The transport mechanisms of interest
(sp...
This paper presents several experiences and conclusions about the usage of the new middleware J2EE platform in an e-commerce framework introducing mobile agent possibilities within the same environment. Main conclusions are taken from Smart-EC project, where J2EE and mobility are considered as a value added in its architecture. Other advanced techn...
The need for deploying high-speed wide area networks has led to the definition of public broadband connectionless services such as SMDS and CBDS. The ITU-T, on the other hand, has established how these services should be supported by the forthcoming BISDN. The recommended solution, known as the direct approach, consists in setting up a Connectionle...
This paper describes a brokering platform for the provision of complex services over the Internet. The platform is able to analyse a request for a complex service, divide it into simple components, and combine several services and products, offered by different providers, into a solution that satisfies the complex request. The platform helps the us...
This article presents different experiences carried out in the connectivity layer of several e-commerce mediation and brokering projects: ABS and ABROSE (supported by the European Programme on Advanced Communications, Technologies, and Services, ACTS) and Smart-EC project (supported by the European Programme on Information Society Technologies, IST...
The IP Multimedia Subsystem (IMS) is the evolu-tion of the 3G mobile telecommunications systems towards All-IP environments supporting all the services working today through switched circuits plus new value added multimedia services (VoIP, video call, video streaming, presence, instant messaging, online gaming, etc.). Based on Internet standards an...
Resumen-Gracias a la mejora de prestaciones proporcionada por la tecnología HSDPA (High Speed Downlink Packet Access), el acceso móvil a Internet ha experimentado un espectacular crecimiento en los últimos años, constituyéndose en alternativa a otras tecnologías de acceso de banda ancha, como el ADSL o el cable. HSDPA se basa en el empleo de un can...