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    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.

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    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.

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    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.

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    Title: Forwarding techniques for IP fragmented packets in a real 6LoWPAN network Authors: Ludovici, Alessandro; Calveras Augé, Anna M.; Casademont Serra, Jordi Abstract: Wireless Sensor Networks (WSNs) are attracting more and more interest since they offer a low-cost solution to the problem of providing a means to deploy large sensor networks in a number of application domains. We believe that a crucial aspect to facilitate WSN diffusion is to make them interoperable with external IP networks. This can be achieved by using the 6LoWPAN protocol stack. 6LoWPAN enables the transmission of IPv6 packets over WSNs based on the IEEE 802.15.4 standard. IPv6 packet size is considerably larger than that of IEEE 802.15.4 data frame. To overcome this problem, 6LoWPAN introduces an adaptation layer between the network and data link layers, allowing IPv6 packets to be adapted to the lower layer constraints. This adaptation layer provides fragmentation and header compression of IP packets. Furthermore, it also can be involved in routing decisions. Depending on which layer is responsible for routing decisions, 6LoWPAN divides routing in two categories: mesh under if the layer concerned is the adaptation layer and route over if it is the network layer. In this paper we analyze different routing solutions (route over, mesh under and enhanced route over) focusing on how they forward fragments. We evaluate their performance in terms of latency and energy consumption when transmitting IP fragmented packets. All the tests have been performed in a real 6LoWPAN implementation. After consideration of the main problems in forwarding of mesh frames in WSN, we propose and analyze a new alternative scheme based on mesh under, which we call controlled mesh under.

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    Title: Modeling the maximum throughput of bluetooth low energy in an error-prone link Authors: Gómez Montenegro, Carlos; Seyfettin Demirkol, Ilker; Paradells Aspas, Josep Abstract: We present an analytical model for the maximum throughput of Bluetooth Low Energy (BLE), considering the presence of uncorrelated bit errors and the impact of a key BLE parameter that defines the time between the start of two consecutive connection events. The derived analysis models the generic application of master-to-slave unidirectional data transmission, which also forms an upper bound for bidirectional data transmission throughput. Simulation results show that our model accurately predicts the maximum BLE throughput for all bit error rates and BLE parameter settings evaluated.

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    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.

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    Title: Optimization of inter-domain presence traffic based on privacy rule sharing: performance and impact on the IMS Authors: Beltrán Martínez, María Victoria; Paradells Aspas, Josep Abstract: Presence information was the key enabler of the great success of instant messaging applications. This information was first limited to simple binary states such as online, offline, or busy. However, it is currently evolving towards a much more generic, flexible concept that includes all context that enables users or applications to adapt and control communications in a more efficient, personalized manner. Presence paves the way for the deployment of advanced communication services and is therefore a key component in Next-Generation Networks. The main barrier to the implantation of next-generation presence-based services is the great amount of traffic involved in the distribution of presence information across domains. In this paper, we give a deep insight into multiple strategies for reducing inter-domain presence traffic. We estimate the capacity demands of these strategies on the IMS servers. Moreover, we enhance two strategies for reducing presence load: Common Subscribe and Federated Common Subscribe. Not only do the proposed enhancements prevent the disclosure of some privacy, they also save presence traffic.

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    Title: A presence-aware smart home system (PASH) Authors: García Davis, Ernesto; Calveras Augé, Anna M. Abstract: Wireless Sensor Networks are providing tremendous benefit for a number of industries. A subset of sensed data collected by these networks is presence information. A smart home control system can be designed based on presence information provided by all devices or objects in the home, and we can act depending on it. For this reason, in this paper we present a Presenceaware Smart Home System. We explain its components and features that facilitate the daily living of person’s own home.

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    Title: Presence-based architecture for wireless sensor networks using publish/subscribe paradigm Authors: García Davis, Ernesto; Calveras Augé, Anna M. 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.

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    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.

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    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 .

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    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.

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    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.

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    Title: TinyCoAP: a novel constrained application protocol (CoAP) implementation for embedding RESTful web services in wireless sensor networks based on TinyOS Authors: Ludovici, Alessandro; Moreno, Pol; Calveras Augé, Anna M. Abstract: In this paper we present the design and implementation of the Constrained Application Protocol (CoAP) for TinyOS, which we refer to as TinyCoAP. CoAP seeks to apply the same application transfer paradigm and basic features of HTTP to constrained networks, while maintaining a simple design and low overhead. The design constraints of Wireless Sensor Networks (WSNs) require special attention in the design process of the CoAP implementation. We argue that better performance and minimal resource consumption can be achieved developing a native library for the operating system embedded in the network. TinyOS already includes in its distribution an implementation of CoAP called CoapBlip. However, this is based on a library not originally designed to meet the requirements of TinyOS. We demonstrate the effectiveness of our approach by a comprehensive performance evaluation. In particular, we test and evaluate TinyCoAP and CoapBlip in a real scenario, as well as solutions based on HTTP. The evaluation is performed in terms of latency, memory occupation, and energy consumption. Furthermore, we evaluate the reliability of each solution by measuring the goodput obtained in a channel affected by Rayleigh fading. We also include a study on the effects that high workloads have on a server.

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    Title: A novel power efficient location-based cooperative routing with transmission power-upper-limit for wireless sensor networks Authors: Shi, Juanfei; Calveras Augé, Anna M.; Cheng, Ye; Liu, Kai Abstract: The extensive usage of wireless sensor networks (WSNs) has led to the development of many power- and energy-efficient routing protocols. Cooperative routing in WSNs can improve performance in these types of networks. In this paper we discuss the existing proposals and we propose a routing algorithm for wireless sensor networks called Power Efficient Location-based Cooperative Routing with Transmission Power-upper-limit (PELCR-TP). The algorithm is based on the principle of minimum link power and aims to take advantage of nodes cooperation to make the link work well in WSNs with a low transmission power. In the proposed scheme, with a determined transmission power upper limit, nodes find the most appropriate next nodes and single-relay nodes with the proposed algorithm. Moreover, this proposal subtly avoids non-working nodes, because we add a Bad nodes Avoidance Strategy (BAS). Simulation results show that the proposed algorithm with BAS can significantly improve the performance in reducing the overall link power, enhancing the transmission success rate and decreasing the retransmission rate.

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    Título: Optimizing the delivery chain in heterogenous networks Autor: Sánchez Loro, Xavier; Paradells Aspas, Josep; Casademont Serra, Jordi; Ferrer, Josep Lluís Resumen: Herein, we will focus on proposing a service taxonomy and classification for RBA/SOA architectures aiming to model a common framework for the description and composition of possible Atomic Ser- vices or networking functions valid for architectures coping with het- erogenous environments. The final objective is fine-tuning the delivery chain to optimize application and delivery performance and behaviour in heterogenous networks. Although our work takes the TARIFA architec- ture as the basis model for our contribution, we think it can be helpful for other architectures dealing with protocol modularization and service composition

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    Título: Smart cities as an application of internet of things: experiences and lessons learnt in Barcelona Autor: Gea, Tomas; Paradells Aspas, Josep; Lamarca, Mariano; Roldan, David Resumen: Internet of things is a ubiquitous technology that will be present everywhere. One of the first applications will be smart cities. Cities are growing in population and citizens demand better services from the administration without increasing taxes. The only way to attend this demand is to improve information and how this is treated to take decisions. In other words, we should make the city smart. Smart cities are a novel concept that defines new technologies but also reuses some of the existing ones. All novel solutions phase the same problem: the lack of standards and widely accepted solutions. The City of Barcelona with the collaboration from research centers and industrial partners has been testing the smart city concept with the double purpose to contribute to the creation of standards and providing in the interim a solution to cope with the heterogeneity of providers, in particular from the wireless sensor part. This work has been structured as a "Barcelona Intelligent City" project or BCI. BCI project considers all the steps of the data process from its capture by a sensor network to the processing to make it relevant (pointing events that requires attention) and rich (with context information). Conclusions from the pilots has started to be applied. One example is the sensoring in civil works control. This paper includes some lines about Avinguda de l'Estatut Civil Works Project and its conclusions.

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    Título: Performance evaluation and compartive analysis of subcarrier modulation Wake-up radio systems for energy-efficient Wireless Sensor Networks Autor: Oller Bosch, Joaquim; Seyfettin Demirkol, Ilker; Casademont Serra, Jordi; Paradells Aspas, Josep; Gamm, Gerd Ulrich; Reindl, Leonhard Michael Resumen: Energy-efficient communication is one of the main concerns of wireless sensor networks nowadays. A commonly employed approach for achieving energy efficiency has been the use of duty-cycled operation of the radio, where the node’s transceiver is turned off and on regularly, listening to the radio channel for possible incoming communication during its on-state. Nonetheless, such a paradigm performs poorly for scenarios of low or bursty traffic because of unnecessary activations of the radio transceiver. As an alternative technology, Wake-up Radio (WuR) systems present a promising energy-efficient network operation, where target devices are only activated in an on-demand fashion by means of a special radio signal and a WuR receiver. In this paper, we analyze a novel wake-up radio approach that integrates both data communication and wake-up functionalities into one platform, providing a reconfigurable radio operation. Through physical experiments, we characterize the delay, current consumption and overall operational range performance of this approach under different transmit power levels. We also present an actual single-hop WuR application scenario, as well as demonstrate the first true multi-hop capabilities of a WuR platform and simulate its performance in a multi-hop scenario. Finally, by thorough qualitative comparisons to the most relevant WuR proposals in the literature, we state that the proposed WuR system stands out as a strong candidate for any application requiring energy-efficient wireless sensor node communications.

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    Título: Channel management in a campus-wide WLAN with partially overlapping channels Autor: Mengual Pérez, Ester; García Villegas, Eduard; Vidal Ferré, Rafael Resumen: The 2.4 GHz ISM band is a battlefield where an increasingly large number of devices compete for the scarce frequency resources. IEEE 802.11 WLANs suffer the consequences of this overcrowded spectrum, especially in dense scenarios where the performance of those WLAN cells is way below the expected in ideal conditions. The harmful effects of interference can be minimized if an intelligent frequency management is implemented. In this paper, we first detail the implementation of a dynamic channel assignment solution which considers partially overlapping channels, and then we show, through measurements in a real campus-wide scenario with near 200 APs and under real traffic conditions, how this approach improves the performance of the traditional three orthogonal channels (i.e. 1, 6 and 11)

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    Título: Uso de canales solapados en una red de área de campus inalámbrica con IEEE 802.11 Autor: Mengual Pérez, Ester; García Villegas, Eduard; Vidal Ferré, Rafael Resumen: Las redes de área local inalámbricas (WLAN) basadas en la familia de estándares IEEE 802.11 utilizan mayoritariamente la banda industrial científica y médica (ISM) de 2,4GHz en la que compiten con un número cada vez mayor de dispositivos. En aquellos escenarios con una mayor densidad de puntos de acceso, esta situación puede derivar en un rendimiento de las celdas WLAN por debajo sus expectativas en condiciones ideales. En este artículo se estudia un escenario real de este tipo: un campus universitario con cerca 200 puntos de acceso y bajo condiciones de tráfico real. En primer lugar, se seleccionan y determinan una serie de parámetros radio con el fin de caracterizar el escenario en términos de carga e interferencias. Este objetivo se consigue a partir de la interacción con las herramientas de gestión de la propia red. A continuación, se implementa una solución de asignación de canales dinámica que interacciona con las mencionadas herramientas de gestión. La gestión de canales implementada se basa en un algoritmo resultado de investigaciones anteriores que, como aspecto novedoso, tiene en cuenta los canales solapados parcialmente. Para terminar, se presentan una serie de pruebas obtenidas del escenario real que permiten demostrar cómo esta aproximación mejora el rendimiento de la tradicional asignación con tres canales ortogonales (i.e. 1, 6 y 11).

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