http://hdl.handle.net/2117/1134 2013-06-20T07:23:00Z http://hdl.handle.net/2117/18557 Title: Adding QoS support for timeliness to the observe extension of CoAP Authors: Ludovici, Alessandro; García, Ernesto; Gimeno, Xavier; Calveras Augé, Anna M. Abstract: In this paper, we propose a modification of the observe extension of CoAP to include Quality of Service (QoS) support for timeliness. The proposed QoS support is based on delivery priority. Nodes are able to express the priority order with which they wish to be notified. Furthermore, they are also able to specify which notification they want to receive. We classify the notifications in two categories: Critical and Non-Critical. The provided QoS is the result of a negotiation between the client and server. The client demands a certain degree of QoS according to its role. The server could accept or negotiate it. This choice depends on the availability of server and network resources. We evaluate our proposal in a real Wireless Sensor Network. An e-health application has been chosen as target of our tests. The performance evaluation is done in terms of average delay, energy consumption and delivery ratio. 2013-04-03T10:08:30Z http://hdl.handle.net/2117/18556 Title: Presence-based architecture for wireless sensor networks using publish/subscribe paradigm Authors: Calveras Augé, Anna M.; Garcia Davis, Ernesto Abstract: Ubiquitous communication is a key component of Ambient Intelligence, enabling objects to communicate with each-other by means of a wireless ad-hoc network. A presence service allows knowing the availability or responsiveness status of elements in a communication (entities). Traditionally, only human use this service, however all smart devices or objects (with embedded wireless sensor nodes) could interact with each other thus a presence service could also enhance communication among them. To achieve this objective we look into existing protocols to propose the requirements needed to provide presence service on Wireless Sensor Networks (WSN). The main contribution of this paper is the discussion of requirements for presence services on WSN and the new proposed architecture to cope with presence services in WSN. 2013-04-03T09:50:03Z http://hdl.handle.net/2117/18332 Title: Implementation of context-aware network architecture for smart objects based on functional composition Authors: Ferrer Riera, José Luis; Sánchez Loro, Xavier; Calveras Augé, Anna M.; Paradells Aspas, Josep Abstract: Lack of flexibility of current Internet architecture led researchers to come up with new paradigms for a novel Internet architecture, which would be able to reduce complexity and increase flexibility compared to current Internet architecture. Functional co mposition is a promising approach to flexible and evolvable architecture design. The idea is composing complex protocol suites by dynamically bind and arrange different functions to obtain certain behavior. Herein, we present the implementation of a contex t - aware network architecture based on functional composition for smart objects. A sub - set of those basic functional blocks has been implemented and validated on an experimental testbed using different network topologies . 2013-03-15T09:39:46Z http://hdl.handle.net/2117/17792 Title: Should we use the default protocol settings for networks of constrained devices? Authors: Betzler, August; Gómez Montenegro, Carlos; Seyfettin Demirkol, Ilker; Paradells Aspas, Josep Abstract: Constrained devices will play a crucial role in the Internet of Things. These devices use communication technologies which often support the formation of wireless multihop topologies. Therefore, end-to-end data transfer involves the collaboration of multiple protocol layers. However, the settings and mechanisms used in a specific layer affect performance of the others. In this paper, we assess a set of crucial network design criteria for potential MAC layer, network layer and transport layer protocols for networks of constrained devices. We evaluate the default and alternative settings and mechanisms for these protocols on a 60-node testbed. The experiments show how performance can be improved significantly by using different settings and mechanisms from the default ones. 2013-02-15T12:57:19Z http://hdl.handle.net/2117/15549 Title: SIP/SIMPLE resource list server : optimization or burden for presence systems Authors: Beltrán Martínez, María Victoria; Paradells Aspas, Josep Abstract: Presence information contains all the context about users, services and devices that applications need to take more proactive and intelligent decisions. SIP/SIMPLE is the de facto framework for initiating, managing and personalizing presencebased communications in the Next-Generation Networks. However, SIMPLE subscription model generates a traffic overload that is restraining mobile operators from implementing advanced presence-based applications. RLS is a widely-adopted optimization of SIMPLE subscription traffic in mobile applications. We analytically measure the presence traffic on the access link between an end-user and the network with and without an RLS. We present the parameters that affect the RLS’ performance and give some guidelines when considering whether or not to use an RLS. 2012-03-13T09:31:18Z http://hdl.handle.net/2117/14336 Title: The impact of channel bonding on 802.11n network management Authors: Deek, Lara; García Villegas, Eduard; Belding, Elizabeth; Lee, Sung-Ju; Almeroth, Kevin Abstract: The IEEE 802.11n standard allows wireless devices to operate on 40MHz-width channels by doubling their channel width fromstandard 20MHz channels, a concept called channel bonding. Increasing channelwidth should increase bandwidth, but it comes at the cost of decreased transmission range and greater susceptibility to interference. However, with the incorporation of MIMO Multiple-Input Multiple-Output) technology in 802.11n, devices can now exploit the increased transmission rates from wider channels at a reduced sacrifice to signal quality and range. The goal of our work is to understand the characteristics of channel bonding in 802.11n networks and the factors that influence that behavior to ultimately be able to predict behavior so that network performance is maximized. We discuss the impact of channel bonding choices as well as the effects of both cochannel and adjacent channel interference on network performance. We discover that intelligent channel bonding decisions rely not only on a link’s signal quality, but also on the strength of neighboring links and their physical rates. 2011-12-28T11:25:49Z http://hdl.handle.net/2117/13367 Title: Alternatives for indoor location estimation on uncoordinated environments Authors: Gorricho Moreno, Juan Luis; Cotrina Navau, Josep Abstract: Approaches based on signal-strength measurements are at present the most popular on indoor location due to their reasonable accuracy and cost effective deployment. In this paper, we present an outlook of our research on different alternatives to implement an indoor location approach based on signal-strength measurements for an uncoordinated environment, an environment where we do not have any control on the number of access points, their location, availability or transmitted power. 2011-09-27T18:29:42Z http://hdl.handle.net/2117/13164 Title: Route change latency in low-power and lossy wireless networks using RPL and 6LoWPAN neighbor discovery Authors: Kermajani, Hamidreza; Gómez Montenegro, Carlos Abstract: The IETF ROLL WG is currently in the final steps of the specification of RPL, a new routing protocol for low power and lossy networks (e.g. wireless sensor networks). RPL may use layer two- and layer three-based mechanisms for neighbor reachability maintenance. Since layer two mechanisms may not always be available, RPL relies by default on the 6LoWPAN Neighbor Discovery, a version of the IPv6 Neighbor Discovery which is optimized for LLNs. This paper provides an analysis of the impact of various RPL and 6LoWPAN Neighbor Discovery parameter settings on the link availability and end-to-end path availability, and the related message overhead. Results show that careful tuning of the relevant parameters is critical for obtaining good network performance. 2011-09-06T18:16:54Z http://hdl.handle.net/2117/12779 Title: Implementation and evaluation of Multi-hop routing in 6LoWPAN Authors: Calveras Augé, Anna M.; Ludovici, Alessandro Abstract: 6LoWPAN enables the transmission of IPv6 packets over LoWPAN networks. In order to make it possible, 6LoWPAN introduces an adaptation layer between network and link layers. This layer allows IPv6 packets to be adapted to the lower layers constraints. It provides fragmentation and reassembling of packets and header compression. It also can be involved in routing decisions. Depending on which layer is responsible of routing decisions 6LoWPAN divides routing in two categories: mesh under if the interested layer is the adaptation layer, route over if it is the network one. In this paper we compare the two routing solutions evaluating their performances in terms of end-to-end delay and round-trip time. All the performance evaluation has been realized in a real implementation of 6LoWPAN. 2011-06-15T13:08:49Z http://hdl.handle.net/2117/12460 Title: Focusing the study on wireless multihop networks Authors: Paradells Aspas, Josep; Gómez Montenegro, Carlos Abstract: Wireless mesh networks, mobile ad-hoc networks and wireless sensor networks are some of the names related to a more general concept that can be described as wireless multihop networks. The topic of the tutorial is motivated for the feeling of lack of connection between reality and theory in the study of this kind of networks. The tutorial starts with an introduction to some applications and the technologies available. From this point, different key aspects such as mobility, range, interference, metrics, routing or power consumption are presented considering different degrees of complexity and realism. The tutorial presents measurements from real systems (e. g. WLAN mesh networks and wireless sensor networks) related to range, packet losses, reconfiguration times and the effects of mobility. The tutorial is intended to focus the research in the area, avoiding too general scenarios that provide no clear solutions and to provide some reference behaviors and values to validate simulation or theoretical results. 2011-05-03T18:16:00Z http://hdl.handle.net/2117/10652 Title: Proceso de inversión de competencias genéricas en los nuevos planes de estudios de grado de la ETSETB de acuerdo con el modelo CDIO Authors: Sayrol Clols, Elisa; Sardà Ferrer, Joan; Sáez Moreno, Germán; Bragós Bardia, Ramon; Alarcón Cot, Eduardo José; Cabrera Beán, Margarita Asuncion; Calveras Augé, Anna M.; Comellas Colomé, Jaume; O'Callaghan Castellà, Juan Manuel; Pegueroles Vallés, Josep R.; Prat Viñas, Lluís Abstract: Los distintos marcos normativos que fijan las condiciones de contorno en la elaboración de los nuevos planes de estudios ponen especial énfasis en el aprendizaje basado en competencias y en la inclusión de determinadas competencias genéricas. Después de comparar diversos planes de estudio y listados de competencias, se han establecido las competencias genéricas que deben incluir los nuevos grados de la ETSETB de la UPC y se ha diseñado su estructura para favorecer su aprendizaje. Para ello se ha utilizado como paradigma el modelo CDIO (Conceive, Design, Implement, Operate). 2010-12-16T14:07:13Z http://hdl.handle.net/2117/10357 Title: Surveillance with alert management system using conventional cell phones Authors: Gorricho Moreno, Juan Luis; Brezmes, Tomas; Cotrina Navau, Josep; Rersa, Marc Abstract: In the present paper we expose the development of a real-time monitoring prototype of human activities using a single cell phone equipped with some sensors. The monitoring system is reduced to the minimum expression; no special hardware is required as far as a conventional cell phone will monitor the user, classify the user activities with respect to a customized rule’s set, and finally trigger the corresponding alerts, when necessary. 2010-11-22T11:44:51Z http://hdl.handle.net/2117/9537 Title: Performance of a time-of-arrival technique for positioning WLAN terminals Authors: Izquierdo, F; Ciurana Adell, Marc; Barceló Arroyo, Francisco; Paradells Aspas, Josep Abstract: Nowadays, several systems are available for outdoor location (i.e GPS, cellular networks based…). However, there is no proper location system for indoor scenarios. The technique presented in this paper proposes the use of the existing wireless LAN infrastructure with minor changes to provide an accurate estimation of the location of mobile devices in indoor environments. This technique is based on round-trip time (RTT) measurements, which are used to estimate TOA and distances between the device to be located and WLAN access points. To avoid the cumbersome modification of the physical layer, each RTT is estimated between the transmission of an IEEE 802.11 link layer data frame and the reception of the associated acknowledgement (ACK). By applying trilateration algorithms, an accurate estimation of the mobile position is calculated. 2010-10-07T11:30:20Z http://hdl.handle.net/2117/8435 Title: Detecting and mitigating the impact of wideband jammers in IEEE 802.11 WLANs Authors: García Villegas, Eduard; Gómez, Moisés; López Aguilera, M. Elena; Casademont Serra, Jordi Abstract: IEEE 802.11 Wireless LANs (WLANs) are highly sensitive to Denial of Service (DoS) attacks carried out with jamming devices. In this paper we focus on 2.4GHz wideband constant jammers. The interest in the wideband jammer lies in the fact that it beats all possible channels at the same time, leaving no possible escape following traditional channel-switching defenses. After studying and developing an effective detection mechanism, we propose the implementation of a load balancing technique based on cell breathing for mitigating the harmful effects of the jammer over an IEEE 802.11 WLAN. Cell breathing is achieved by dynamically tuning the transmission power to adjust the size of a WLAN cell. 2010-07-28T09:07:28Z http://hdl.handle.net/2117/7867 Title: Impacto de mecanismos de seguridad en sensores IEEE 802.15.4 Authors: Tripp Barba, Carolina; Casademont Serra, Jordi Abstract: En la actualidad son muchos los mecanismos de seguridad que el estándar IEEE 802.15.4 permite a las redes inalámbricas de sensores [1] Dicho estándar define las especificaciones de la Capa de Acceso al Medio y la Capa Física de los dispositivos inalámbricos de área personal. La última revisión corresponde al 2006. Dichas revisiones y actualizaciones son hechas por el grupo de trabajo 802.15. Sin embargo estos mecanismos consumen recursos como memoria y batería, que son un poco limitados en estos dispositivos. Además de contribuir a los retardos en la comunicación. Por lo cual, en el presente trabajo se presenta de manera práctica el impacto que el uso de mecanismos de seguridad tienen en el desempeño de este tipo de redes. Para ello se hizo una comparación de dicho desempeño de manera teórica basándose en lo presentado en [2], con los valores óptimos apegados a lo especificado en el estándar IEEE 802.15.4, en contraste con pruebas reales. Para estas pruebas se hizo uso del sistema operativo TinyOS [3] y de las operaciones de seguridad MAC (Capa de Acceso al Medio) ofrecidas por el chip CC2420 usado en las motas TelosB. Además se presenta el desgaste de la batería, el cual es otro punto importante que se desea conservar en los sensores. 2010-06-28T13:25:05Z