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Network-on-Chip (NoC) is currently the paradigm of choice for covering the on-chip communication needs of multicore processors. As we reach the manycore era, though, electrical interconnects present performance and power issues that are exacerbated in the presence of multicast communications due to the point-to-point nature of NoCs. This dramatically limits the available design space in terms of manycore architecture, sparking the need for new solutions. In this direction, the use of wireless interconnects has been recently proposed as a complement of a wired plane. In this paper, the concept of Graphene-enabled Wireless Network-on-Chip (GWNoC) is introduced, which extends the native broadcast capabilities of existing wireless NoCs by enabling the per-core integration of antennas that radiate in the terahertz band (0.1 - 10 THz). Preliminary results on the feasibility of GWNoC are presented, covering implementation, on-chip networking and multiprocessor architecture aspects., Peer Reviewed, Postprint (published version)

Networks-on-Chip (NoCs) are emerging as the way to interconnect the processing cores and the memory within a chip multiprocessor. As recent years have seen a significant increase in the number of cores per chip, it is crucial to guarantee the scalability of NoCs in order to avoid communication to become the next performance bottleneck in multicore processors. Among other alternatives, the concept of Wireless Network-on- Chip (WNoC) has been proposed, wherein on-chip antennas would provide native broadcast capabilities leading to enhanced network performance. Since energy consumption and chip area are the two primary constraints, this work is aimed to explore the area and energy implications of scaling a WNoC in terms of (a) the number of cores within the chip, and (b) the capacity of each link in the network. To this end, an integral design space exploration is performed, covering implementation aspects (area and energy), communication aspects (link capacity) and networklevel considerations (number of cores and network architecture). The study is entirely based upon analytical models, which will allow to benchmark the WNoC scalability against a baseline NoC. Eventually, this investigation will provide qualitative and quantitative guidelines for the design of future transceivers for wireless on-chip communication., Peer Reviewed, Postprint (author’s final draft)

Traditionally, efficient inter-domain data delivery may be implemented either as a network or as an application layer multicast service. However, while the former has seen little uptake due to prohibitive deployment costs the latter is widely used today, but often without a minimum guaranteed performance. In this paper we present Lcast, a network-layer single-source multicast framework designed to merge the robustness and efficiency of IP multicast with the configurability and low deployment cost of application-layer overlays. The architecture involves no end-host changes and only requires the upgrading of a small set of routers to support the Locator/ID Separation Protocol (LISP), an incrementally deployable enhancement to the current global routing infrastructure. Content distribution over the Internet's core is done by means of a router overlay while within domains, end-hosts interface with Lcast using conventional multicast protocols. The overlay's scalability and topological configurability is sustained by logically centralizing group management. We illustrate the versatility of our solution by designing and assessing the scalability and performance of three management strategies for low latency content distribution. Our analysis is based on large scale simulations supported by realistic user behavior and Internet-like network topologies. The results show Lcast's low management overhead and ability to optimize delivery to meet various operational constraints. Notably, we find that it can deliver traffic with latencies close to unicast ones, independent of overlay size., Peer Reviewed, Postprint (published version)

Energy-harvesting-enabled wireless sensor networks (EHE-WSN), despite their disruptive potential impact, still present several challenges precluding practical deployability. In particular, the low power density and random character of the ambient energy sources produce slow deep fadings in the energy that nodes harvest. Unfortunately, the capacity of the energy buffers is very limited, causing that, at some times, the node might interrupt its operation due to lack of stored energy. In this context, a general purpose framework for dimensioning the energy buffer is provided in this work. To achieve this, a dynamics-decoupled, multi-source capable energy model is presented, which can handle fast random patterns of the communications and the energy harvesting, while it can capture slow variations of the ambient energy in both time and space. By merging both dynamics, the model can more accurately evaluate the performance of the sensor node in terms of the energy storage capacity and to estimate the expected energy of the neighboring nodes. In order to evaluate the performance of the sensor node, a statistical unit for energy harvesting resources, referred as the Energy-Erlang (E2), has been defined. This unit provides a link between the energy model, the environmental harvested power and the energy buffer. The results motivate the study of the specific properties of the ambient energy sources before the design and deployment. By combining them in this general-purpose framework, electronics and network designers will have a powerful tool for optimizing resources in EHE-WSNs., Peer Reviewed, Postprint (published version)

Multi-source energy harvesters are gaining interest as a robust alternative to power wireless sensors, since the sensor node can maintain its operation regardless of the fact that one of its energy sources might be temporarily unavailable. Interestingly, and less explored, when the energy availability of the energy sources present large temporal variations, combining multiple energy sources reduce the overall sparsity. As a result, the performance of a multiple energy harvester powered sensor node is significantly better compared to a single energy source which harvests the same amount of energy. In this context, a circuit area optimization framework for multiple source energy harvesting powered systems is proposed. This framework takes advantage of this improvement in performance to provide the optimal amount of energy harvesters, the requirements of each energy harvester and the required energy buffer capacity, such that the overall area or volume is minimized. As the results show, by conducting a joint design of the energy harvesters and the energy buffer, the overall area or volume of a sensor node can be significantly reduced. © 2014 IEEE., Peer Reviewed, Postprint (published version)

Premi extraordinari doctorat 2013-2014, Nanosystems, integrated systems with a total size of a few micrometers, are capable of interacting at the nanoscale, but their short operating range limits their usefulness in practical macro-scale scenarios. Nanonetworks, the interconnection of nanosystems, will extend their range of operation by allowing communication among nanosystems, thereby greatly enhancing their potential applications. In order to integrate communication capabilities into nanosystems, their communication subsystem needs to shrink to a size of a few micrometers. There are doubts about the feasibility of scaling down current metallic antennas to such a small size, mainly because their resonant frequency would be extremely high (in the optical domain) leading to a large free-space attenuation of the radiated EM waves. In consequence, as an alternative to implement wireless communications among nanosystems, two novel paradigms have emerged: molecular communication and graphene-enabled wireless communications. On the one hand, molecular communication is based on the exchange of molecules among nanosystems, inspired by communication among living cells. In Diffusion-based Molecular Communication (DMC), the emitted molecules propagate throughout the environment following a diffusion process until they reach the receiver. On the other hand, graphene, a one-atom-thick sheet of carbon atoms, has been proposed to implement graphene plasmonic RF antennas, or graphennas. Graphennas with a size in the order of a few micrometers show plasmonic effects which allow them to radiate EM waves in the terahertz band. Graphennas are the enabling technology of Graphene-enabled Wireless Communications (GWC). In order to answer the question of how communication networks will scale when their size shrinks, this thesis presents a scalability analysis of the performance metrics of communication networks to the nanoscale, following a general model with as few assumptions as possible. In the case of DMC, two detection sche, Award-winning, Postprint (published version)

Multicast on-chip communications are expected to become an important concern as the number of cores grows and we reach the manycore era. The increasing importance such traffic flows directly contrasts with the diminishing multicast performance of current Network-on-Chip (NoC) designs, and has lead to a surge of research works that seek to improve on-chip multicast support. Within this context, one-to-many traffic models may become useful for the early-stage design and evaluation of these proposals. However, existing models do not distinguish between unicast and multicast flows and often do not consider different multiprocessor sizes. To bridge this gap, a multicast scalability analysis is presented, aiming to provide tools for the modeling of multicast communications for NoC design and evaluation purposes., Peer Reviewed, Postprint (published version)

ThecurrentInternetarchitecturewasnotdesignedtoeasilyaccommodatemobil- ity because IP addresses are used both to identify and locate hosts. The Locator/Identifier Separation Protocol (LISP) decouples them by considering two types of addresses: EIDs that identify hosts, and RLOCs that identify network attachment points and are used as routing locators. LISP, with such separation in place, can also offer native mobility. LISP-MN is a particular case of LISP which specifies mobility. In this paper we provide a comprehensive tutorial on LISP-MN, showing its main features and how it compares to existing mobility protocols, Peer Reviewed, Postprint (published version)

Projecte realitzat en col·laboració amb l'empresa myBus GmbH., L’objectiu principal del projecte és el desenvolupament de les eines web per representar les dades posicionals dels transports monitoritzats i facilitar així la seva consulta mitjançant interfícies que habilitin la cerca de dades complexes i sobre diferents situacions i fer-ho en entorns gràfics que s’adaptin a la naturalesa de la informació.

Projecte realitzat en el marc d'un programa de mobilitat amb el Politecnico di Torino, The goal of this work is developing the most possibly abstract solution for making a user roam in different networks, without dropping his active connections. Better, design a network architecture in charge of maintaining user's connections and being transparent to the user at the same time.

In the last decade, the field of microprocessor architecture has seen the rise of multicore processors, which consist of the interconnection of a set of independent processing units or cores in the same chip. As the number of cores per multiprocessor increases, the bandwidth and energy requirements for their interconnection networks grow exponentially and it is expected that conventional on-chip wires will not be able to meet such demands. Alternatively, nanophotonics has been regarded as a strong candidate for chip communication since it could provide high bandwidth with low area and energy footprints. However, issues such as the unavailability of efficient on-chip light sources or the difficulty of implementing all-optical buffering or header processing hinder the development of scalable photonic on-chip networks. In this paper, the area and laser power of several photonic on-chip network proposals is analytically modeled and its scalability is evaluated. Also, a graphene-based hybrid wireless/optical-wired approach is presented, aiming at enabling end-to-end photonic on-chip networks to scale beyond thousands of cores, Peer Reviewed, Postprint (published version)

Graphene-enabled Wireless Communications (GWC) advocate for the use of graphene-based plasmonic antennas, or graphennas, which take advantage of the plasmonic properties of graphene to radiate electromagnetic waves in the terahertz band (0.1-10 THz). GWC may represent a breakthrough in the research areas of wireless on-chip communications, i.e., among the different processors or cores of a chip multiprocessor, and of these cores with the memory system. The main advantages of the resulting Graphene-enabled Wireless Networks on-Chip (GWNoC) are twofold. On the one hand, the potential of GWCto radiate in the terahertz band provides a huge transmission bandwidth, allowing not only the transmission of information at extremely high speeds but also the design of ultra-low-power and low-complexity schemes. On the other hand, the size of graphennas can be greatly reduced with respect to metallic antennas with the same resonant frequency, allowing the integration of graphennas within individual processing cores and the implementation of core-level wireless communication. In addition to these physical layer advantages, GWNoC represent a clear opportunity from the multicore architecture perspective. Due to their native implementation of broadcast and multicast communications, GWNoC will enable not just the alleviation of the latency or power bottlenecks of traditional on-chip networks, but also the devising of novel multicore architectures., Peer Reviewed, Postprint (published version)

Graphene-enabled wireless communications constitute a novel paradigm which has been proposed to implement wireless communications among nanosystems. Indeed, graphene-based plasmonic nano-antennas, or graphennas, just a few micrometers in size have been predicted to radiate electromagnetic waves at the terahertz band. In this work, the important role of the graphene conductivity in the characteristics of graphennas is analyzed, and their radiation performance both in transmission and reception is numerically studied. The resonance frequency of graphennas is calculated as a function of their length and width, both analytically and by simulation. Moreover, the influence of a dielectric substrate with a variable size, and the position of the patch with respect to the substrate is also evaluated. Further, important properties of graphene, such as its chemical potential or its relaxation time, are found to have a profound impact in the radiation properties of graphennas. Finally, the radiation pattern of a graphenna is compared to that of an equivalent metallic antenna. These results will prove useful for designers of future graphennas, which are expected to enable wireless communications among nanosystems., Peer Reviewed, Postprint (published version)

Nanotechnology has allowed building nanomachines capable of performing simple tasks, such as sensing, data storage, and actuation. Nanonetworks, networks of nanomachines, will allow cooperation and information sharing among them, thereby greatly expanding the applications of nanotechnology in the biomedical, environmental,and industrial fields. One of the most promising paradigms to implement nanonetworks is diffusion-based molecular communication (DMC). In DMC, nanomachines transmit information by the emission of molecules that diffuse throughout the medium until they reach their destination. Most of the existing literature in DMC has focused on the analysis of its physical channel. In this work, the key differences of the physical channel of DMC with respect to the wireless electromagnetic channel are reviewed with the purpose of learning how they impact the design of networks using DMC. In particular, we find that the uniqueness of the physical channel of DMC will require revisiting most of the protocols and techniques developed for traditional wireless networks in order to adapt them to DMC networks. Furthermore, guidelines for the design of a novel network architecture for DMC networks, including fundamental aspects such as coding, medium access control, addressing, routing and synchronization, are provided., Postprint (published version)

The scattering of terahertz radiation on a graphene-based nano-patch antenna is numerically analyzed. The extinction cross section of the nano-antenna supported by silicon and silicon dioxide substrates of different thickness are calculated. Scattering resonances in the terahertz band are identified as Fabry–Perot resonances of surface plasmon polaritons supported by the graphene film. A strong tunability of the antenna resonances via electrostatic bias is numerically demonstrated, opening perspectives to design tunable graphene-based nano-antennas. These antennas are envisaged to enable wireless communications at the nanoscale., Peer Reviewed, Postprint (published version)

Use of graphene nano antennas in multicore processor to beyond the limit of number of cores., [ANGLÈS] In a wireless Network-on-Chip system, two main factors are size of antennas and bandwidth. The small size of antennas opens the possibility to integrate one antenna per core, whereas their high bandwidth allows faster communication speed. Graphene based antennas offer perfect compromise of both small size and high bandwidth and for this reason, graphene is gaining importance in the field of wireless Network-on-Chip. A wireless Network-on-Chip system based on graphene nano-antennas working in the THz range is analyzed in this thesis. In order to analyze WNoC systems, we consider a set of antennas deployed in an intra-chip scenario. In order to get meaningful results for antennas, simulations should be done in different environments. By getting the simulation results of antennas in free space and using them for comparison with results in a surrounded environment, we can get a better idea of the relationship between the size of these antennas and efficiency. A WNoC system based on graphene enabled antennas is described in this paper. The main advantage of WNoC system is that we can inherit the properties of wireless communication. These properties are able to make the system more scalable as well as provide higher communication speed., [CASTELLÀ] En un sistema de red inalámbrica-on-Chip, hay dos factores principales que son el tamaño de las antenas y el ancho de banda. El pequeño tamaño de las antenas abre la posibilidad de integrar una antena por núcleo, mientras que el gran ancho de banda permite una más rápida velocidad de comunicación. Las antenas basadas en grafeno ofrecen una excelente combinación de pequeño tamaño y gran ancho de banda y, por esta razón, el grafeno está ganando importancia en el campo de la tecnología inalámbrica de red-on-Chip. En esta tesis se analiza un sistema de red inalámbrica-on-Chip basado en nanoantenas de grafeno que trabaja en el rango de THz. Con el fin de analizar los sistemas WNoC, consideramos un conjunto de antenas desplegadas en un escenario intra-chip. Con el fin de conseguir resultados significativos para antenas, las simulaciones se deben hacer en diferentes ambientes. Al obtener los resultados de la simulación de antenas en el espacio libre y su uso para la comparación con los resultados en su entorno, podemos tener una mejor idea de la relación entre el tamaño de estas antenas y la eficiencia. Un sistema WNoC basado en antenas de grafeno habilitadas se describe en este documento. La principal ventaja del sistema WNoC es que podemos heredar las propiedades de la comunicación inalámbrica. Estas propiedades son capaces de hacer el sistema más escalable así como proporcionar una mayor velocidad de comunicación., [CATALÀ] En un sistema de xarxa sense fils-on-Chip, hi ha dos factors principals que són la mida de les antenes i l'ample de banda. La mida petita de les antenes obre la possibilitat d'integrar una antena per nucli, mentre que el gran ample de banda permet una més ràpida velocitat de comunicació. Les antenes basades en grafè ofereixen una excel·lent combinació de petita grandària i gran ample de banda i per això el grafè està guanyant importància en el camp de la tecnologia sense fils de xarxa-on-Chip. En aquesta tesi s'analitza un sistema de xarxa sense fils-on-Chip basat en nanoantenes de grafè que treballa en el rang de THz. Per tal d'analitzar els sistemes WNoC, considerem un conjunt d'antenes desplegades en un escenari intra-xip. Per tal d'aconseguir resultats significatius per a antenes, les simulacions s'ha de fer en diferents ambients. En obtenir els resultats de la simulació d'antenes en l'espai lliure i el seu ús per a la comparació amb els resultats en l'entorn, podem tenir una millor idea de la relació entre la mida d'aquestes antenes i l'eficiència. Un sistema WNoC basat en antenes de grafè habilitades es descriu en aquest document. El principal avantatge del sistema WNoC és que podem heretar les propietats de la comunicació sense fils. Aquestes propietats permeten fer el sistema més escalable així com proporcionar una major velocitat de comunicació.

El propósito de este proyecto es el desarrollo de un monitor de redes 802.11 que analice la utilización y pérdida de paquetes de las redes, de forma no intrusiva, en base a los paquetes beacons enviados por los puntos de acceso.

The sustained growth of the global routing table is exerting an economical strain on ISPs by requiring untimely router upgrades. Notably, it has been speculated that the growth rate of router FIBs is surpassing that of its supporting technology and that the deployment of IPv6 is only to make matters worse. In this paper, we propose LISP-MPS, an architecture based on LISP, that isolates the intra-domain routing of an Autonomous System (AS) from its inter-domain routing. The resulting separation implies the decrease of backbone routing table sizes and enables an AS to control the forwarding of traffic inside its network. For a seamless, cost effective, and incremental deployment, LISP-MPS leverages iBGP to implement the LISP mapping system functionality with minimal modification to a small subset of deployed equipment. Finally, an analysis of realistic topologies shows that, despite changing how packets transit a network, the architecture does not lose resilience to failures. Moreover, we show that it can be a viable alternative to BGP/MPLS deployments due to its low implementation cost., Peer Reviewed, Postprint (published version)

We designed N3Sim in order to simulate a set of nanomachines which communicate through molecular diffusion in a fluid medium., Peer Reviewed, Postprint (published version)

P2P-TV is an emerging alternative to classical television broadcast systems. Leveraging possibilities offered by the Internet, several companies offer P2P-TV services to their customers. The overwhelming majority of these systems, however, is of closed nature, offering little insight on their traffic properties. For a better understanding of the P2P- TV landscape, we performed measurement experiments in France, Japan, Spain, and Romania, using different commercial applications. By using multiple measurement points in different locations of the world, our results can paint a global picture of the measured networks, inferring their main properties. More precisely, we focus on the level of collaboration between peers, their location and the effect of the traffic on the networks. Our results show that there is no fairness between peers and that is an important issue for the scalability of P2P-TV systems. Moreover, hundreds of Autonomous Systems are involved in the P2P-TV traffic and it points out the lack of locality-aware mechanisms for these systems. The geographic location of peers testifies the wide spread of these applications in Asia and highlights their worldwide usage., Peer Reviewed, Postprint (published version)

Nanonetworking is an emerging field of research at the intersection of nanotechnology and communication networks. Molecular Communication (MC) is a bio-inspired paradigm, where nanonetworks, i.e., the interconnection of nanodevices, are implemented based on the exchange of molecules. Within this paradigm, one of the most promising techniques is diffusion-based MC, which relies on free diffusion to transport the molecules from a transmitter to a receiver. In this work, we explore the main characteristics of diffusion-based MC through the use of N3Sim, a physical simulation framework for MC which allows the simulation of the physics underlying the diffusion of molecules in different scenarios. Through the results obtained with N3Sim, the Linear Time Invariant (LTI) property is proven to be a valid assumption for the normal diffusion-based MC scenario. Moreover, diffusion-based noise is observed and evaluated with reference to existing stochastic models. Furthermore, the optimal pulse shape for diffusion-based MC is found to be a narrow spike. Finally, four different pulse-based coding techniques are compared in terms of the available bandwidth, ISI and energy consumption for communication; On–Off Keying is found to be the most suitable scheme in the evaluated scenario., Peer Reviewed, Postprint (published version)

English: Nanotechnology is enabling the development of devices in a scale ranging from a few to hundreds of nanometers. Communication between these devices greatly expands the possible applications, increasing the complexity and range of operation of the system. In particular, the resulting nanocommunication networks (or nanonetworks) show great potential for applications in the biomedical field, in which diffusion-based molecular communication is regarded as a promising alternative to electromagnetic-based solutions due to the bio-stability and energy-related requirements of this scenario. In this new paradigm, the information is encoded into pulses of molecules that reach the receiver by means of diffusion. However, molecular signals suffer a significant amount of attenuation as they propagate through the medium, thus limiting the transmission range. In this work we propose, among others, a signal amplification scheme for molecular communication nanonetworks in which a group of emitters jointly transmits a given signal after achieving synchronization by means of Quorum Sensing. By using the proposed methodology, the transmission range is extended proportionally to the number of synchronized emitters. We also provide an analytical model of Quorum Sensing, validated through simulation. This model accounts for the activation threshold (which will eventually determine the resulting amplification level) and the delay of the synchronization process., Castellano: La nanotecnología permite el desarrollo de dispositivos en una escala que va de las unidades a centenares de nanómetros. La comunicación entre estos dispositivos hace aumentar el número de aplicaciones posibles, ya que se mejora la complejidad y el rango de actuación del sistema. En concreto, las redes de nanocomunicaciones (o nanoredes) resultantes muestran un gran potencial cuando se trata de aplicaciones biomédicas, en las cuales la comunicación molecular basada en difusión de partículas supera a las soluciones electromagnéticas clásicas debido a las imposiciones energéticas y de biocompatibilidad de este escenario. En este nuevo paradigma de comunicación, la información se codifica en pulsos de moléculas que llegan al receptor gracias al fenómeno de la difusión. No obstante, las señales moleculares son sometidas a una gran atenuación a medida que se propagan a través del medio, hecho que limita severamente el alcance o rango de transmisión. En esta tesis se propone, entre otros, un esquema de amplificación de la señal para nanoredes de comunicación molecular, en el cual un grupo de emisores transmite una cierta señal de manera conjunta después de haberse sincronizado mediante la ejecución de Quorum Sensing. Con el método que proponemos, el alcance aumenta proporcionalmente al número de transmisores que se sincronizan. Además, proponemos un modelo analítico de Quorum Sensing, el cual se valida mediante simulación. Dicho modelo permite calcular el nivel umbral de activación del conjunto (hecho que determina la amplificación resultante y el rango de transmisión final) y el retardo que el proceso de sincronización introduce., Català: La nanotecnologia permet el desenvolupament de dispositius en una escala de unitats a centenars de nanòmetres. La comunicació entre aquests dispositius fa augmentar el nombre de possibles aplicacions, ja que es millora la complexitat i el rang d'actuació del sistema. En concret, les xarxes de nanocomunicacions (o nanoxarxes) resultants mostren un gran potencial quan ens referim a aplicacions biomèdiques, en les quals la comunicació molecular basada en difusió de partícules supera a les solucions de caire electromagnètic degut a les imposicions energètiques i de biocompatilitat d'aquest escenari. En aquest nou paradigma de comunicació, la informació és codificada en polsos de molècules que arriben al receptor gràcies al fenomen de la difusió. No obstant, els senyals moleculars són sotmesos a una gran atenuació a mesura que es propaguen a través del medi, fet que limita severament el rang de transmissió. En aquesta tesi es proposa, entre d'altres, un esquema d'amplificació del senyal per a nanoxarxes de comunicació molecular, en el qual un grup d'emissors transmet un cert senyal de manera conjunta després d'haver-se sincronitzat executant Quorum Sensing. Amb el mètode que proposem, l'abast o rang de transmissió augmenta proporcionalment al nombre d'emissors que se sincronitzen. A més a més, proposem un model analític de Quorum Sensing, el qual és validat mitjançant simulació. Dit model permet calcular el nivell llindar d'activació del conjunt (que de fet determina l'amplificació resultant i el rang de transmissió final) i el retard que el procés de sincronització introdueix.

Català: El treball és una exploració del canal de difusió molecular per nanoredes moleculars, en el qual s'identifica la resposta impulsional i en freqüència del canal, es comprova la seva linealitat i invariància i s'extreuen les principals característiques de comunicació. S'avaluen diferents tècniques de modulació., Castellano: El trabajo es una exploración del canal de difusión molecular para nanoredes moleculares, en el cual se identifica la respuesta impulsional y en frecuencia del canal, se comprueba su linealidad e invarianza y se extraen las principales características de comunicación. Se evalúan diferentes técnicas de modulación., English: In this work, the diffusion-based MC channel is explored in order to extract its main communication metrics, such as attenuation and delay with respect to frequency and distance. The LTI property is proven to be a valid assumption for normal diffusion-based single/multi-transmitter scenarios. Different pulse-based modulation techniques are compared by means of throughput, operation range, energy requirements and ISI, and the optimal pulse shape for these modulations is provided. Finally, interferences are evaluated in a broadcast communication scenario and diffusion-based noise is observed and assessed with reference to already proposed stochastic models.The exploration of the physical diffusion-based communication channel is based on simulations.

L'adopció de les especificacions del 802.11 no té sense precedents. En qualsevol punt es poden trobar múltiples xarxes sense fils, i cada cop aquestes tecnologies són presents en una varietat de dispositius més gran : tablets, smartphones, portàtils, etc. El projecte introdueix teoria bàsica sobre el funcionament de l'estàndar 802.11 i basant-se en articles recents de recerca, crea una eina que valida, de forma pràctica, que es poden obtenir mesures confiables de congestió de xarxes sense fils. El funcionament de l'eina és vàlida de forma experimental tant en entorns controlats de laboratori com en mesures sobre desplegaments de xarxa operacionals.

Diffusion-based molecular communication is a promising bio-inspired paradigm to implement nanonetworks, i.e., the interconnection of nanomachines. The peculiarities of the physical channel in diffusion-based molecular communication require the development of novel models, architectures and protocols for this new scenario, which need to be validated by simulation. With this purpose, we present N3Sim, a simulation framework for diffusion-based molecular communication. N3Sim allows to simulate scenarios where transmitters encode the information by releasing molecules into the medium, thus varying their local concentration. N3Sim models the movement of these molecules according to Brownian dynamics, and it also takes into account their inertia and the interactions among them. Receivers decode the information by sensing the particle concentration in their neighborhood. The benefits of N3Sim are multiple: the validation of channel models for molecular communication and the evaluation of novel modulation schemes are just a few examples., Peer Reviewed, Postprint (author’s final draft)

Nano-networks are the interconnection of nano-machines and as such expand the limited capabilities of a single nano-machine. Several techniques have been proposed so far to interconnect nano-machines. For short dis- tances (nm-mm ranges), researchers are proposing to use molecular motors and calcium signaling. For long distances (mm-m), pheromones are envisioned to transport information. In this work we propose a new mechanism for medium-range communications (nm- m): agellated bacteria. This technique is based on the transport of DNA-encoded information between emitters and receivers by means of a bacterium. We present a physical channel characterization and a simulator that, based on the previous characterization, simulates the transmission of a DNA-packet between two nano-machines., Preprint

The Internet evolved from its early days of being a small research network to become a critical infrastructure many organizations and individuals rely on. One dimension of this evolution is the continuous growth of the number of participants in the network, far beyond what the initial designers had in mind. While it does work today, it is widely believed that the current design of the global routing system cannot scale to accommodate future challenges. In 2006 an Internet Architecture Board (IAB) workshop was held to develop a shared understanding of the Internet routing system scalability issues faced by the large backbone operators. The participants documented in RFC 4984 their belief that "routing scalability is the most important problem facing the Internet today and must be solved." A potential solution to the routing scalability problem is ending the semantic overloading of Internet addresses, by separating node location from identity. Several proposals exist to apply this idea to current Internet addressing, among which the Locator/Identifier Separation Protocol (LISP) is the only one already being shipped in production routers. Separating locators from identifiers results in another level of indirection, and introduces a new problem: how to determine location, when the identity is known. The first part of our work analyzes existing proposals for systems that map identifiers to locators and proposes an alternative system, within the LISP ecosystem. We created a large-scale Internet topology simulator and used it to compare the performance of three mapping systems: LISP-DHT, LISP+ALT and the proposed LISP-TREE. We analyzed and contrasted their architectural properties as well. The monitoring projects that supplied Internet routing table growth data over a large timespan inspired us to create LISPmon, a monitoring platform aimed at collecting, storing and presenting data gathered from the LISP pilot network, early in the deployment of the LISP protocol. The pro, Postprint (published version)

Scattering of the terahertz radiation on a graphene-based nano-antenna is considered. Different electromagnetic models of graphene are discussed and applied to calculate extinction, scattering and absorption cross sections of the nano-antenna. Scattering resonances in the terahertz band are identified as longitudinal Fabry-Perot resonances of surface plasmon polaritons supported by the graphene layer. A simple while powerful model, based on the effective mode index of plasmon polaritons, is proposed to predict the antenna resonant properties. A systematic numerical study of the graphene-based nano-antenna is presented for different antenna dimensions. Finally, the potential of graphene-based nano-antennas for terahertz applications is discussed., Peer Reviewed, Postprint (published version)

English: Nanotechnology is enabling the development of devices in a scale ranging from one to a few hundred nanometers, known as nanomachines. How these nanomachines will communicate is still an open debate. Molecular communication is a promising paradigm that has been proposed to implement nanonetworks, i.e., the interconnection of nanomachines. The peculiarities of the physical channel in diffusion-based molecular communication require the development of novel models, architectures and protocols for this new scenario, which need to be validated by simulation. With this purpose, N3Sim, a simulator for diffusion-based molecular communication has been developed. N3Sim allows simulating scenarios where transmitters encode the information by releasing molecules into the medium, thus varying their local concentration. N3Sim models the movement of these molecules according to Brownian dynamics, and it also takes into account their inertia and the interactions among them. Receivers decode the information by sensing the particle concentration in their neighborhood. The benefits of N3Sim are multiple: the validation of channel models for molecular communication and the evaluation of novel modulation schemes are just a few examples.

In this paper, we define a set of metrics that characterize the local stability properties of path-vector routing protocols such as BGP (Border Gateway Protocol). By means of these stability metrics, we propose a method to analyze the effects of BGP policy- and protocol-induced instability on local routers., Peer Reviewed, Postprint (published version)

Postprint (published version)

Molecular communication is a promising paradigm to implement nanonetworks, the interconnection of nanomachines. Catalytic nanomotors constitute one of the techniques that have been proposed for medium-range molecular communications. This paper presents a physical channel characterization that shows how nanomachines communicate using catalytic nanomotors as information carriers. Quantitative results of the packet transmission delay and loss probability are then obtained through simulation. Finally, some trade-offs that will arise when designing these networks are outlined., Peer Reviewed, Postprint (published version)

We have developed a LISP simulator (CoreSim). CoreSim is an Internet-scale LISP deployment simulator. It is able to replay a packet trace and simulate the behavior of a LISP Ingress Tunnel Router (ITR) and the associated Mapping Resolver, on top of a topology based on measurements performed by the iPlane infrastructure. It reports mapping lookup latency, the load imposed on each node of the MS and cache performance statistics. The simulator implements LISP-ALT and LISP-DHT. In this technical report we validate our LISP-DHT implementation, present an estimator for the latencies not reported by iPlane and discuss the architecture of CoreSim., Preprint

The Available Bandwidth (AB) of an end-to-end path is its remaining capacity and it is an important metric for several applications such as overlay routing and P2P networking. That is why many AB estimation tools have been published recently. Most of these tools use the Probe Rate Model, which requires sending packet trains at a rate matching the AB. Its main issue is that it congests the path under measurement. We present a different approach: a novel passive methodology to estimate the AB that does not introduce probe traffic. Our methodology, intended to be applied between two separate nodes, estimates the path’s AB by analyzing specific parameters of the traffic exchanged. The main challenge is that we cannot rely on any given rate of this traffic. Therefore we rely on a different model, the Utilization Model. In this paper we present our passive methodology and a tool (PKBest) based on it. We evaluate its applicability and accuracy using public NLANR data traces. Our results -more than 300Gb- show that our tool is more accurate than pathChirp, a state-of-the-art active PRM-based tool. At the best of the authors’ knowledge this is the first passive AB estimation methodology., Preprint

Wireless technologies are rapidly evolving and the users are demanding the possibility of changing its point of attachment to the Internet (i.e. default router) without breaking the IP communications. This can be achieved by using Mobile IP or NEMO, however mobile clients must forward its data packets through its Home Agent (HA) in order to communicate with its peers. This sub-optimal route (lack of route optimization) reduces considerably the communications performance, increases the delay and the infrastructure load. Additionally, since the HA must forward all the mobile clients’ data packets, it can become the bottleneck of such networks. In this paper we present the fP2P-HN architecture, a P2P-based solution that allows deploying several HAes throughout the Internet. With this architecture a mobile client can select a closer HA to its topological position in order to reduce the delay of the paths towards its peers. Furthermore it incorporates flexible HAes that, as we will see, reduce the load at these entities. The main challenge of our solution is signaling the location of the HAes in Internet. We provide an analytical model that evaluates the costs and the benefits of the fP2P-HN architecture. The model shows that the signaling grows logarithmically with the number of HAes and that the reduction is, at least, 20% (lower bound)., Peer Reviewed, Postprint (published version)

Wireless technologies are rapidly evolving and the users are demanding the possibility of changing its point of attachment to the Internet (i.e Access Router) without breaking the IP communications. This can be achieved by using Mobile IPv6. However mobile clients must forwards its data packets addressed towards its home network through a special entity, the Home Agent (HA). This HA is a key point when considering the performance of Mobile IPv6-based networks., Preprint

The Home Agent (HA) is a key point when considering the performance of Mobile IPv6-based networks. This paper presents the first steps towards characterizing the load of a HA. This may be useful both for researchers that aim to propose novel architectures that improve the performance of the HAs and for ISPs willing to deploy Mobile IPv6. To achieve our goals first we analyzed the internal traffic of a medium-size department. Then we reviewed the existing models and we evaluated their applicability to this particular scenario. Our results showed that the estimated load of a HA serving a medium-size department (around 1500 hosts) is high with a maximum throughput of 262 Mbps., Postprint (published version)

La palabra “Movilidad” en el contexto de las nuevas tecnologías de la información y de las telecomunicaciones, se refiere a la capacidad de comunicación, entretenimiento y trabajo desde cualquier sitio y dispositivo. Técnicamente movilidad es la capacidad de cambiar de punto de acceso manteniendo las conexiones de red. Expresado de esta manera, parece un concepto sencillo, pero se sustenta en un complejo conjunto de aplicaciones, plataformas tecnológicas, protocolos y servicios que se interconectan y sincronizan para brindar esa libertad de no estar atado a un lugar fijo. Existen diferentes propuestas para que IP se encargue de la gestión de la movilidad, mediante el protocolo Mobile IP [1] estandarizado por la IETF [2], encargado de solucionar el problema de los cambios de punto de acceso. A estos cambios de punto de acceso a la red se les denomina handover. Durante esta fase el nodo móvil no es capaz de enviar ni recibir paquetes lo cual provoca pérdidas y retardos de paquetes. Este problema es crítico en aplicaciones con requerimientos de tiempo real. Para mejorar el rendimiento del handover, la IETF ha definido diversos protocolos para usar junto a Mobile IP, entre ellos Fast Handover for Mobile IPv6 [3]. El objetivo de este proyecto es contribuir al desarrollo de una herramienta de estudio del protocolo Fast Handover for Mobile IPv6 partiendo de una implementación previa, fruto de un PFC anterior [4]. En este PFC se trata de estandarizar esta implementación previa realizada a partir del draft de Fast Handover for Mobile IPv6 [5] utilizando el actual RFC del mismo protocolo y marcar el camino a seguir para una implantación sencilla de este protocolo en un entorno Linux.