Papers by Manuel Alvarez-campana
Supporting multiple traffic classes with different QoS (Quality of Service) constraints in third ... more 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 with its controller, because there can be many instances of it. We have approached the dimensioning of this interface from the perspective of simulation, concretely for the UMTS (Universal Mobile Telecommunications System) access network. At this respect we have developed a simulation model capable of representing multi-service scenarios inside this particular UTMS interface. This tool can be fed with traffic of different types, representing the different traffic classes defined for UMTS, and is able to simulate traffic differentiation both at ATM (Asynchronous Transfer Mode) and AAL2 (ATM Adaptation Layer 2) level. In the paper we presen...
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— The IP Multimedia Subsystem (IMS) is considered the current Service Delivery Platform standard ... more — The IP Multimedia Subsystem (IMS) is considered the current Service Delivery Platform standard for providing multimedia services in Next Generation Networks (NGN). Although fleet management services are traditionally focused on voice communications, they are evolving towards broadband multimedia ones. For this reason, this paper presents an open IMS-based platform that provides advanced multimedia professional services in the aforementioned scenario. After a detailed analysis of the fleet communication requirements, the IMS-based architecture of the platform is presented. Then, the deployed services are described, from the basic ones to those more advanced, e.g. Push-To-Talk (PTT) and videoconferencing. It stands out the feature of the platform, which provides an environment that facilitates the development, deployment and integration of new services. We finally discuss the importance of the contributions made by the platform for the fleet management scenarios.
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The efficient support of multiple traffic classes with different quality of service requirements ... more 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 we present a simulation model of the ATM-based UMTS (Universal Mobile Telecommunications System) terrestrial radio access network. The simulator aims to provide a test bed for conducting further research studies on several topics of potential interest. In particular, we intend to use the tool for dimensioning ATM links, for evaluating performance under different mixes of traffic classes, and for investigating quality of service mechanisms. This wide range of applications has led us to develop a very flexible simulation model that captures many low level details. Some preliminary results obtained with the simulator are presented in order to...
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HSDPA technology has been recently introduced by UMTS mobile operators as a solution both for inc... more HSDPA technology has been recently introduced by UMTS 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 performance of TCP traffic over HSDPA from the user perspective based on experiments and measurements over a real network. The effect of multiple HSDPA users sharing the overall capacity of the cell is explicitly considered. The results show that HSPDA quality of experience is comparable to that achievable on fixed access technologies such as ADSL or Cable networks. In addition, we prove that by adequately tuning TCP parameters, the performance can be significantly improved.
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Abstract- The access transport infrastructure of a cellular communications network represents a s... more Abstract- 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 Release of the system) and the multi-service nature of the traffic to be carried rise the dimensioning process complexity. At this respect, we have developed a simulation tool for supporting the network designer when making dimensioning and physical topology decisions related to Iub interface (between each UMTS base station and its controller), which is the most critical interface of UMTS access network. This simulator is capable of modelling the presence of multiple traffic classes as well as the Iub transport protocol stack with enough accuracy; it offers a graphical configuration interface and has been designed to have a great fl...
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Sensors
Estimating the number of people present in a given venue in real-time is extremely useful from a ... more Estimating the number of people present in a given venue in real-time is extremely useful from a security, management, and resource optimization perspective. This article presents the architecture of a system based on the use of Wi-Fi sensor devices that allows estimating, almost in real-time, the number of people attending an event that is taking place in a venue. The estimate is based on the analysis of the “probe request” messages periodically transmitted by smartphones to determine the existence of Wi-Fi access points in the vicinity. The method considers the MAC address randomization mechanisms introduced in recent years in smartphones, which prevents the estimation of the number of devices by simply counting different MAC addresses. To solve this difficulty, our Wi-Fi sensors analyze other fields present in the header of the IEEE 802.11 frames, the information elements, to extract a unique fingerprint from each smartphone. The designed system was tested in a set of real scenar...
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This article focuses on the dimensioning of the UMTS (Universal Mobile Telecommunications System)... more 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 optimum transmission capacities necessary to satisfy the QoS (Quality of Service) requirements of each UMTS traffic class, specifically at the interface between each base station and its controller. By using a suitable simulation model, we obtain dimensioning rules for some significant UMTS applications. Also, some basic ATM traffic multiplexing strategies are examined in order to investigate their possible benefits regarding QoS parameters improvement or transmission capacity savings.
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Proceedings of the 15th International Conference on Availability, Reliability and Security, 2020
Traditional static risk assessment and management are currently not enough in most of the scenari... more Traditional static risk assessment and management are currently not enough in most of the scenarios where the cybersecurity context of an organization varies dynamically. New threats that may affect to the organization can appear, suspicious activity is detected, etc. These changes are not taken into account by a static risk assessment as it is carried out unresponsively to these sudden changes in the context. This paper proposes a dynamic risk management system with the capability of reacting to those rapid changes in the context of the organization. This system is responsible for collecting multiple data from different types of sensors (presence, environmental, wifi, Bluetooth, network anomaly, work climate, etc.) and detecting anomalies in such data using correlation techniques. This architecture also counts with a prediction module that mathematically models the attacks, using Hidden Markov Models and Bayesian networks, and tries to estimate the next step of the attacker. Also, ...
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En el libro se analizan con detalle las principales tecnologias de acceso de banda ancha, conside... more En el libro se analizan con detalle las principales tecnologias de acceso de banda ancha, considerando tanto sus caracteristicas tecnicas de prestaciones y escalabilidad, como su adecuacion para prestar servicios de telecomunicacion. Ademas, se estudian las aproximaciones actuales hacia la convergencia de redes, en un contexto en el que los operadores buscan ofrecer paquetes de servicios cada vez mas completos, con el objetivo de mejorar su posicion competitiva y captar nuevos clientes. Asimismo, se incluye un analisis del grado de competencia de los mercados de telecomunicaciones y la situacion e influencia de los procesos regulatorios en curso, prestando especial atencion a los segmentos de mercado de acceso de banda ancha y de acceso movil, por ser los dos motores del crecimiento del sector en la actualidad. Se han analizado las siguienes tecnologias de acceso de banda ancha: Redes hibridas de fibra y cable (HFC), Bucle digital de abonado (xDSL), Fibra optica (FTTx), Redes WiMAX,...
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The support of multiple traffic classes with different Quality of Service (QoS) requirements pose... more 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 the general issue of UMTS (Universal Mobile Telecommunications System) access network dimensioning, from a practical point of view. Our objective is to give an overall view of the main parameters and design alternatives that can be considered in a real deployment scenario.
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HSDPA technology has been recently introduced by UMTS mobile operators as a solution both for inc... more HSDPA technology has been recently introduced by UMTS 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 performance of TCP traffic over HSDPA from the user perspective based on experiments and measurements over a real network. The effect of multiple HSDPA users sharing the overall capacity of the cell is explicitly considered. The results show that HSPDA quality of experience is comparable to that achievable on fixed access technologies such as ADSL or Cable networks. In addition, we prove that by adequately tuning TCP parameters, the performance can be significantly improved.
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The MEHARI system provides a low-cost programmable and scalable tool for the analysis of IP/ATM t... more The MEHARI system provides a low-cost programmable and scalable tool for the analysis of IP/ATM traffic. The system runs on one or several PCs, thus allowing increasing the processing capacity as required. The tool can be configured to capture either IP headers or whole IP packets, being possible to concentrate the analysis on specific traffic flows by using VPI/VCI or IP address filters. The captured traffic is analyzed on the fly so that the samples are discarded as soon as the different application modules process them. The application modules perform the analysis of the IP packets/headers. The system has been designed so that the output of one module may feed the input of the following. This approach allows the addition of new applications at different processing levels. An especially interesting application developed for the MEHARI system is the Traffic Classification Module. This application performs a classification of IP flows (packets sharing the same IP origin/destination ...
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This paper focuses on the Call Control for the establishment and release of isochronous calls wit... more This paper focuses on the Call Control for the establishment and release of isochronous calls within the DAMS network (ESPRIT project #2146), a distributed ISDN PBX over an FDDI-II backbone optical ring that supports both isochronous and asynchronous traffic generated by ISDN terminals, LAN terminals, and Bandwidth On Demand (BOD) terminals. After a general overview of the DAMS network architecture, the Call Control functional model and its procedures are described. Special emphasis is put on the CCITT Q.931-based signalling protocols and the enhancements required to allow the interworking of ISDN/BOD terminals and FDDI-II.
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Sensors
University campuses are normally constituted of large buildings responsible for high energy deman... more University campuses are normally constituted of large buildings responsible for high energy demand, and are also important as demonstration sites for new technologies and systems. This paper presents the results of achieving energy sustainability in a testbed composed of a set of four buildings that constitute the Telecommunications Engineering School of the Universidad Politécnica de Madrid. In the paper, after characterizing the consumption of university buildings for a complete year, different options to achieve more sustainable use of energy are presented, considering the integration of renewable generation sources, namely photovoltaic generation, and monitoring and controlling electricity demand. To ensure the implementation of the desired monitoring and control, an internet of things (IoT) platform based on wireless sensor network (WSN) infrastructure was designed and installed. Such a platform supports a smart system to control the heating, ventilation, and air conditioning (...
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Applied Sciences
New computational and technological paradigms that currently guide developments in the informatio... more New computational and technological paradigms that currently guide developments in the information society, i.e., Internet of things, pervasive technology, or Ubicomp, favor the appearance of new intrusion vectors that can directly affect people’s daily lives. This, together with advances in techniques and methods used for developing new cyber-attacks, exponentially increases the number of cyber threats which affect the information society. Because of this, the development and improvement of technology that assists cybersecurity experts to prevent and detect attacks arose as a fundamental pillar in the field of cybersecurity. Specifically, intrusion detection systems are now a fundamental tool in the provision of services through the internet. However, these systems have certain limitations, i.e., false positives, real-time analytics, etc., which require their operation to be supervised. Therefore, it is necessary to offer architectures and systems that favor an efficient analysis o...
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Wireless Communications and Mobile Computing
In a more and more urbanized World, the so-called Smart Cities need to be driven by the principle... more In a more and more urbanized World, the so-called Smart Cities need to be driven by the principles of efficiency and sustainability. Information and Communications Technologies and, in particular, the Internet of Things will play a key role on this, since they will allow monitoring and optimizing all the municipal services that exist and shall exist. People flow monitoring stands out in this context due to its wide range of applications, spanning from monitoring transport infrastructure to physical security applications. There are different techniques to perform people flow monitoring, presenting pros and cons, as in any other engineering problem. Typically, the options that provide the most accurate results are also the most expensive ones, whereas there are cases where presence detection in given areas is enough and cost is a limiting factor. The main goal of this paper is to prove that a minimal deployment of sensors, combined with the adequate analysis and visualization algorith...
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Sensors (Basel, Switzerland), Jan 8, 2017
Internet of Things platforms for Smart Cities are technologically complex and deploying them at l... more 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 in this context. The IoT platform deployed across the engineering schools of the Universidad Politécnica de Madrid in the Moncloa Campus of International Excellence represents a good example of a test bench for experimentation with Smart City services. This paper presents the main features of this platform, putting special emphasis on the technological challenges faced and on the solutions adopted, as well as on the functionality, services and potential that the platform offers.
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Proceedings of 8th Mediterranean Electrotechnical Conference on Industrial Applications in Power Systems, Computer Science and Telecommunications (MELECON 96), 1996
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2004 IEEE 15th International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE Cat. No.04TH8754), 2004
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Papers by Manuel Alvarez-campana