Tecnologías middleware para el desarrollo de servicios en entornos de computación ubicua

En esta Tesis doctoral realizamos contribuciones en el campo de la definición de tecnologías middleware para el desarrollo de servicios en entornos de computación ubicua. En primer lugar, abordamos el problema del descubrimiento de servicios, que permitirá que de forma automática un dispositivo descubra los servicios ofrecidos por otros dispositivos que le rodean. Aunque existen propuestas en este sentido, no cubren todas las necesidades que imponen estos nuevos entornos de computación, por lo que hemos definidio un nuevo mecanismo de descubrimiento: Pervasive Discovery Protocol (PDP). En sengudo lugar, proponemos el uso de la tecnología de agentes móviles como middleware para el desarrollo de servicios en entornos ubicuos. Los agentes se caracterizan por estar orientados a realizar tareas, por ser autónomos, por su capacidad de cooperar y si poseen la característica de movilidad, por ser capaces de moverse a sistemas remotos para realizar sus tareas, minimizando el coste de las comunicaciones. Estas características se adaptan a las restricciones que imponen la computación ubicua. En esta línea, contribuimos a la adaptación del estándar de agentes FIPA para su funcionamiento en estos entornos, y en concreto, nos centramos en el Directory Faciliator (DF). Estas propuestas nos han llevado a participar de forma activa en el comité técnico FIPA Ad-Hoc. _________________________________________________In this Ph.D. dissertation, we contribute to the definition of middleware technologies for the development of services in pervasive computing environments. First, we broach the problem of service discovery, that allow devices to automatically discover the services offered by other devices in their surroundings. Although other proposais exist, we think none of them fulfils the needs of these new environments, so we have defined a new discovery mechanism: the Pervasive Discovery Protocol (PDP). PDP is a new protocol designed for local scopes, fully distributed, where requests and replys are both multica,sted, and where each device stores in a local cache the advertisements listened so far and shares this information with the devices arround it. PDP manages to reduce the number of messages transmited per service request while obtaining high service discovery ratios, and besides it makes devices with greater availability time to answer flrst, so minimizing the battery dram of the more power-constrained ones. Secondly, we propose the use of mobile agents technology as the middleware for the development of services in a pervasive computing nvironment. Agents are characterized by their autonomous and goal-oriented behaviour, their ability to cooperate with other agents and, if mobile, they are able to move to remote systems to carry out their task, so minimizing the communication cost. These characteristics fit well into the restrictions that pervasive computing impose. We also aim to adapt the FIPA standard to these environments; specifically, we concentrate in the yellow pages service, the so called Directory Facilitator (DF). In our solution, we define a new agent, the Service Discovery Agent (SDA), that uses an underlaying implementation of our service discovery protocol, PDP, to make efficient searches of remote services, removing the mechanism of DFs federation defined by FIPA. These proposais have been presented and discussed in the FIPA Ad-Hoc Technical Commitee, after what we were invited to take part and are now an active member of it

Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks

Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead.This work is partially supported by the Spanish Ministry of Science and Innovation through the Continuity of Service, Security and QoS for Transportation Systems (CONSEQUENCE) (TEC2010-20572-C02-01/02) and INcident monitoRing In Smart COmmunities (INRISCO) (TEC2014-54335-C4-2-R) projects. We thank the editor and anonymous reviewers for their constructive comments, which helped us to improve our manuscript

Detecting and Reducing Biases in Cellular-Based Mobility Data Sets

Correctly estimating the features characterizing human mobility from mobile phone traces is a key factor to improve the performance of mobile networks, as well as for mobility model design and urban planning. Most related works found their conclusions on location data based on the cells where each user sends or receives calls or messages, data known as Call Detail Records (CDRs). In this work, we test if such data sets provide enough detail on users' movements so as to accurately estimate some of the most studied mobility features. We perform the analysis using two different data sets, comparing CDRs with respect to an alternative data collection approach. Furthermore, we propose three filtering techniques to reduce the biases detected in the fraction of visits per cell, entropy and entropy rate distributions, and predictability. The analysis highlights the need for contextualizing mobility results with respect to the data used, since the conclusions are biased by the mobile phone traces collection approach.This research was partially funded by the Spanish Ministry of Economy, Industry and Competitiveness through TEC2017-84197-C4-1-R (Inteligencia de fuentes abiertas para redes electricas inteligentes seguras), TEC2014-54335-C4-2-R (INRISCO: INcident monitoRing In Smart COmmunities), and IPT-2011-1272-430000 (MONOLOC) projects

Entropy-Based Anomaly Detection in Household Electricity Consumption

Energy efficiency is one of the most important current challenges, and its impact at a global level is considerable. To solve current challenges, it is critical that consumers are able to control their energy consumption. In this paper, we propose using a time series of window-based entropy to detect anomalies in the electricity consumption of a household when the pattern of consumption behavior exhibits a change. We compare the accuracy of this approach with two machine learning approaches, random forest and neural networks, and with a statistical approach, the ARIMA model. We study whether these approaches detect the same anomalous periods. These different techniques have been evaluated using a real dataset obtained from different households with different consumption profiles from the Madrid Region. The entropy-based algorithm detects more days classified as anomalous according to context information compared to the other algorithms. This approach has the advantages that it does not require a training period and that it adapts dynamically to changes, except in vacation periods when consumption drops drastically and requires some time for adapting to the new situation.This work was supported by the Spanish Government under the research project “Enhancing Communication Protocols with Machine Learning while Protecting Sensitive Data (COMPROMISE)” (PID2020-113795RB-C32 MCIN/AEI/10.13039/501100011033) and the project MAGOS (TEC2017-84197-C4-1-R), and by the Comunidad de Madrid (Spain) under the projects: CYNAMON (P2018/TCS-4566), co-financed by the European Structural Funds (ESF and FEDER), and the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M21), in the context of the V PRICIT (Regional Programme of Research and Technological Innovation)

Real time detection of malicious DoH traffic using statistical analysis

The DNS protocol plays a fundamental role in the operation of ubiquitous networks. All devices connected to these networks need DNS to work, both for traditional domain name to IP address translation, and for more advanced services such as resource discovery. DNS over HTTPS (DoH) solves certain security problems present in the DNS protocol. However, malicious DNS tunnels, a covert way of encapsulating malicious traffic in a DNS connection, are difficult to detect because the encrypted data prevents performing an analysis of the content of the DNS traffic. In this study, we introduce a real-time system for detecting malicious DoH tunnels, which is based on analyzing DoH traffic using statistical methods. Our research demonstrates that it is feasible to identify in real-time malicious traffic by analyzing specific parameters extracted from DoH traffic. In addition, we conducted statistical analysis to identify the most significant features that distinguish malicious traffic from benign traffic. Using the selected features, we achieved satisfactory results in classifying DoH traffic as either benign or malicious

Supporting L3 femtocell mobility using the MOBIKE protocol

Proceeding of ACCESS 2011, The Second International Conference on Access Networks, Luxembourg City, Luxembourg, June 19-24, 2011Femtocells can be used to improve the indoor coverage and bandwidth of 3G cellular networks in homes and buildings. They are designed to be placed in a fixed location. However, their use would also be interesting in mobile environments such as public transportation systems. This paper studies the mobility limitations at the layer 3 and suggests an approach to support mobility on femtocell networks. This solution employs the protocols already defined in the femtocell architecture, minimizing thus the impact on it.This work has been supported by the Spanish Ministry of Science and Innovation, CONSEQUENCE project (TEC2010- 20572-C02-01) and partially supported by the Madrid regional community project CCG10-UC3M/TIC-4992

A Bandwidth-Efficient Dissemination Scheme of Non-Safety Information in Urban VANETs

The recent release of standards for vehicular communications will hasten the development of smart cities in the following years. Many applications for vehicular networks, such as blocked road warnings or advertising, will require multi-hop dissemination of information to all vehicles in a region of interest. However, these networks present special features and difficulties that may require special measures. The dissemination of information may cause broadcast storms. Urban scenarios are especially sensitive to broadcast storms because of the high density of vehicles in downtown areas. They also present numerous crossroads and signal blocking due to buildings, which make dissemination more difficult than in open, almost straight interurban roadways. In this article, we discuss several options to avoid the broadcast storm problem while trying to achieve the maximum coverage of the region of interest. Specifically, we evaluate through simulations different ways to detect and take advantage of intersections and a strategy based on store-carry-forward to overcome short disconnections between groups of vehicles. Our conclusions are varied, and we propose two different solutions, depending on the requirements of the application.This work was partially founded by the Spanish Ministry of Science and Innovation within the framework of projects TEC2010-20572-C02-01 “CONSEQUENCE” and TEC2014-54335-C4-2-R “INRISCO” and by the Regional Government of Madrid within the “eMadrid” project under Grants S2009/TIC-1650 and S2013/ICE-2715, including the costs to publish in open access

Performance evaluation of CoAP and MQTT with security support for IoT environments

World is living an overwhelming explosion of smart devices: electronic gadgets, appliances, meters, cars, sensors, camera and even traffic lights, that are connected to the Internet to extend their capabilities, constituting what is known as Internet of Things (IoT). In these environments, the application layer is decisive for the quality of the connection, which has dependencies to the transport layer, mainly when secure communications are used. This paper analyses the performance offered by these two most popular protocols for the application layer: Constrained Application Protocol (CoAP) and Message Queue Telemetry Transport (MQTT). This analysis aims to examine the features and capabilities of the two protocols and to determine their feasibility to operate under constrained devices taking into account security support and diverse network conditions, unlike the previous works. Since IoT devices typically show battery constraints, the analysis is focused on bandwidth and CPU use, using realistic network scenarios, since this use translates to power consumption.This work was supported in part by the Ministry of Economy and Competitiveness (Spain) under the project MAGOS (TEC2017-84197-C4-1-R) and by the Comunidad de Madrid (Spain) under the projects: CYNAMON (P2018/TCS-4566), co-financed by European Structural Funds (ESF and FEDER), and the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M21), in the context of the V PRICIT (Regional Programme of Research and Technological Innovation)

Selection and publication of network interface cards in multihomed pervasive computing devices

Proceedings of the 8th IEEE International Workshop on Middleware and system support for pervasive computing, march 21-25, 2011, Seattle, USAMany modern devices come with several, heterogeneous, network interface cards (NICs). However, simple operations like transferring data flows to the cheapest NIC or to one with enough Quality of Service (QoS) are awkward tasks on most Operating Systems. In this paper, we discuss the criteria to select the proper NIC for a given data flow. We also present a new Operating System service, called netqos, to publish data and figures of merit for these criteria. The main objective of netqos is providing relevant information to applications and middleware about NIC selection criteria, isolating them from the idiosyncrasies of the many QoS gathering tools and allowing to choose the proper NIC to fit their needs. We have built this new service as a synthetic file system for the Linux kernel. We describe our experiences in using it in a real-world scenario and the practical and inherent limitations of this approachProyecto CCG10-UC3M/TIC-4992 de la Comunidad Autónoma de Madrid y la Universidad Carlos III de Madri

Analysis of location prediction performance of LZ algorithms using GSM Cell-based location data

Proceedings of the 5th International Symposium of Ubiquitous Computing and Ambient Intelligence (UCAMI 2011), December 5-8th, 2011, Riviera Maya, MexicoPredictions about users' next locations allow bringing forward their future context, thus having additional time to react. To make such predictions, algorithms capable of learning mobility patterns and estimating the next location are needed. This work is focused on making the predictions on mobile terminals, thus resource consumption being an important constraint. Among the predictors with low resource consumption, the family of LZ algorithms has been chosen to study their performance, analyzing the results drawn from processing location records of 95 users. The main contribution is to divide the algorithms into two phases, thus being possible to use the best combination to obtain better prediction accuracy or lower resource consumption.Proyecto CCG10-UC3M/TIC-4992 de la Comunidad Autónoma de Madrid y la Universidad Carlos III de Madri