http://hdl.handle.net/2117/1080 2013-05-19T17:54:54Z 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/2117/16081 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. 2012-06-18T14:39:06Z http://hdl.handle.net/2117/16080 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. 2012-06-18T14:29:14Z http://hdl.handle.net/2117/16008 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. 2012-06-10T15:24:39Z 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/2117/14985 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. 2012-02-06T18:49:06Z http://hdl.handle.net/2117/14793 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. 2012-01-25T09:54:24Z 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