121 research outputs found
Deteção de intrusões de rede baseada em anomalias
Dissertação de mestrado integrado em Eletrónica Industrial e ComputadoresAo longo dos últimos anos, a segurança de hardware e software tornou-se uma grande preocupação. À medida
que a complexidade dos sistemas aumenta, as suas vulnerabilidades a sofisticadas técnicas de ataque têm
proporcionalmente escalado. Frequentemente o problema reside na heterogenidade de dispositivos conectados ao
veículo, tornando difícil a convergência da monitorização de todos os protocolos num único produto de segurança.
Por esse motivo, o mercado requer ferramentas mais avançadas para a monitorizar ambientes críticos à vida
humana, tais como os nossos automóveis.
Considerando que existem várias formas de interagir com os sistemas de entretenimento do automóvel como
o Bluetooth, o Wi-fi ou CDs multimédia, a necessidade de auditar as suas interfaces tornou-se uma prioridade,
uma vez que elas representam um sério meio de aceeso à rede interna do carro. Atualmente, os mecanismos de
segurança de um carro focam-se na monitotização da rede CAN, deixando para trás as tecnologias referidas e não
contemplando os sistemas não críticos. Como exemplo disso, o Bluetooth traz desafios diferentes da rede CAN,
uma vez que interage diretamente com o utilizador e está exposto a ataques externos.
Uma abordagem alternativa para tornar o automóvel num sistema mais robusto é manter sob supervisão as
comunicações que com este são estabelecidas. Ao implementar uma detecção de intrusão baseada em anomalias,
esta dissertação visa analisar o protocolo Bluetooth no sentido de identificar interações anormais que possam
alertar para uma situação fora dos padrões de utilização. Em última análise, este produto de software embebido
incorpora uma grande margem de auto-aprendizagem, que é vital para enfrentar quaisquer ameaças desconhecidas
e aumentar os níveis de segurança globais. Ao longo deste documento, apresentamos o estudo do problema seguido
de uma metodologia alternativa que implementa um algoritmo baseado numa LSTM para prever a sequência de
comandos HCI correspondentes a tráfego Bluetooth normal. Os resultados mostram a forma como esta abordagem
pode impactar a deteção de intrusões nestes ambientes ao demonstrar uma grande capacidade para identificar padrões anómalos no conjunto de dados considerado.In the last few years, hardware and software security have become a major concern. As the systems’ complexity
increases, its vulnerabilities to several sophisticated attack techniques have escalated likewise. Quite often, the
problem lies in the heterogeneity of the devices connected to the vehicle, making it difficult to converge the monitoring
systems of all existing protocols into one security product. Thereby, the market requires more refined tools to monitor
life-risky environments such as personal vehicles.
Considering that there are several ways to interact with the car’s infotainment system, such as Wi-fi, Bluetooth,
or CD player, the need to audit these interfaces has become a priority as they represent a serious channel to reach
the internal car network. Nowadays, security in car networks focuses on CAN bus monitoring, leaving behind the
aforementioned technologies and not contemplating other non-critical systems. As an example of these concerns,
Bluetooth brings different challenges compared to CAN as it interacts directly with the user, being exposed to external
attacks.
An alternative approach to converting modern vehicles and their set of computers into more robust systems
is to keep track of established communications with them. By enforcing anomaly-based intrusion detection this
dissertation aims to analyze the Bluetooth protocol to identify abnormal user interactions that may alert for a non conforming pattern. Ultimately, such embedded software product incorporates a self-learning edge, which is vital to
face newly developed threats and increasing global security levels. Throughout this document, we present the study
case followed by an alternative methodology that implements an LSTM based algorithm to predict a sequence of
HCI commands corresponding to normal Bluetooth traffic. The results show how this approach can impact intrusion
detection in such environments by expressing a high capability of identifying abnormal patterns in the considered
data
Übertragungstechnologien, Simulation und Entwurf robuster Regelungen für drahtlose Feldgeräte in der Industrie
Nach über zwei Jahrzehnten seit dem Beginn der Verbreitung von Funktechnologien im alltäglichen Lebensumfeld gibt es zunehmend Bestrebungen, drahtlose Technologien auch im industriellen Bereich und insbesondere auf Feldebene einzusetzen. Begünstig wird dies durch die Einführung von energieverbrauchsarmen Funktechnologien und Protokollen wie beispielsweise WirelessHART, ISA100.11a, ZigBee und Bluetooth Low Energy. Zu Beginn dieser Arbeit und aktuell werden drahtlose Technologien von der Industrie hauptsächlich für Diagnose und Konfigurationszwecke genutzt. Die vorliegende Arbeit geht einen Schritt weiter und hat die Zielsetzung zu untersuchen, inwieweit drahtlose Technologien auch im geschlossenen Regelkreis betrieben werden können. Durch ihre hohe Flexibilität eignet sich die Funkkommunikation auch für das Themenfeld der "Industrie 4.0"', was ebenfalls im Verlauf dieser Arbeit berücksichtigt wird.
Zunächst werden die für diese Arbeit relevanten Kommunikationsstandards sowie deren Aufbau allgemein betrachtet. Daraufhin werden die verwendeten Funkprotokolle WirelessHART, Bluetooth, Bluetooth Low Energy und ein auf dem MAC-Layer basierendes Protokoll vorgestellt. Es wird ein Vergleich der für die Regelungstechnik relevanten Eigenschaften, der Sicherheit und des Implementierungsaufwandes durchgeführt. Nachdem die Protokolle vorgestellt worden sind, wird eine Vorgehensweise zum Entwurf von Regelungen gezeigt. Damit verbunden wird ein in dieser Arbeit zusammengestellter Netzwerksimulator vorgestellt, mit dem es möglich ist, geregelte Systeme realistisch zu simulieren, die das WirelessHART-Protokoll zur Übertragung von Messwerten und/oder Stellgrößen nutzen. Schließlich wird eine Hardware-in-the-Loop (HiL) Simulation vorgestellt, die in Verbindung mit beliebigen Netzwerkprotokollen nutzbar ist.
Da drahtlose Netzwerke in Abhängigkeit vom verwendeten Protokoll bei der Werteübermittlung einer über der Zeit variierenden Totzeit unterliegen, wird eine Methode zur Nachbildung von Totzeiten für lineare Systeme beschrieben. Außerdem werden die Unterschiede zwischen zentraler und lokaler Regelung vorgestellt und insbesondere deren Eignung für Regelkreise mit drahtlosen Übertragungsstrecken diskutiert. Schließlich wird auf den Betrieb von mehreren Regelkreisen im selben Funknetzwerk eingegangen und besonders die Problematik hinsichtlich der Übertragungssynchronisierung bei MIMO-Systemen mit kommerziellen Produkten aufgezeigt. Gleichzeitig wird ein Ansatz vorgestellt, wie ein Protokoll aufgebaut sein kann, damit sowohl die Synchronisation der Messwertaufnahme als auch der Betrieb mehrerer Regelkreise in einem Multi-Hop-Funknetzwerk realisierbar sind. Nachdem eine Verbindung zwischen den Eigenschaften von drahtlosen Netzwerkprotokollen und den Anforderungen von Regelungen hergestellt ist, werden ausgewählte Regelungsverfahren vorgestellt. Dabei handelt es sich um einen Gain-Scheduling-Regler, ein Konzept von Yokogawa, einen Predictive-Outage-Compensator und ein Multiraten-Konzept. All diese Regelungsverfahren werden am Beispiel eines Anlagenprüfstands anhand von Simulationen, HiL-Simulationen und Messungen am realen Versuchsstand veranschaulicht und bewertet
Transmission Modeling with Smartphone-based Sensing
Infectious disease spread is difficult to accurately measure and model. Even for well-studied pathogens, uncertainties remain regarding the dynamics of mixing behavior and how to balance simulation-generated estimates with empirical data. Smartphone-based sensing data promises the availability of inferred proximate contacts, with which we can improve transmission models. This dissertation addresses the problem of informing transmission models with proximity contact data by breaking it down into three sub-questions.
Firstly, can proximity contact data inform transmission models? To this question, an extended-Kalman-filter enhanced System Dynamics Susceptible-Infectious-Removed (EKF-SD-SIR) model demonstrated the filtering approach, as a framework, for informing Systems Dynamics models with proximity contact data. This combination results in recurrently-regrounded system status as empirical data arrive throughout disease transmission simulations---simultaneously considering empirical data accuracy, growing simulation error between measurements, and supporting estimation of changing model parameters. However, as revealed by this investigation, this filtering approach is limited by the quality and reliability of sensing-informed proximate contacts, which leads to the dissertation's second and third questions---investigating the impact of temporal and spatial resolution on sensing inferred proximity contact data for transmission models.
GPS co-location and Bluetooth beaconing are two of those common measurement modalities to sense proximity contacts with different underlying technologies and tradeoffs. However, both measurement modalities have shortcomings and are prone to false positives or negatives when used to detect proximate contacts because unmeasured environmental influences bias the data. Will differences in sensing modalities impact transmission models informed by proximity contact data? The second part of this dissertation compares GPS- and Bluetooth-inferred proximate contacts by accessing their impact on simulated attack rates in corresponding proximate-contact-informed agent-based Susceptible-Exposed-Infectious-Recovered (ABM-SEIR) models of four distinct contagious diseases. Results show that the inferred proximate contacts resulting from these two measurement modalities are different and give rise to significantly different attack rates across multiple data collections and pathogens.
While the advent of commodity mobile devices has eased the collection of proximity contact data, battery capacity and associated costs impose tradeoffs between the frequency and scanning duration used for proximate-contact detection. The choice of a balanced sensing regime involves specifying temporal resolutions and interpreting sensing data---depending on circumstances such as the characteristics of a particular pathogen, accompanying disease, and underlying population. How will the temporal resolution of sensing impact transmission models informed by proximity contact data? Furthermore, how will circumstances alter the impact of temporal resolution? The third part of this dissertation investigates the impacts of sensing regimes on findings from two sampling methods of sensing at widely varying inter-observation intervals by synthetically downsampling proximity contact data from five contact network studies---with each of these five studies measuring participant-participant contact every 5 minutes for durations of four or more weeks. The impact of downsampling is evaluated through ABM-SEIR simulations from both population- and individual-level for 12 distinct contagious diseases and associated variants of concern. Studies in this part find that for epidemiological models employing proximity contact data, both the observation paradigms and the inter-observation interval configured to collect proximity contact data exert impacts on the simulation results. Moreover, the impact is subject to the population characteristics and pathogen infectiousness reflective (such as the basic reproduction number, ). By comparing the performance of two sampling methods of sensing, we found that in most cases, periodically observing for a certain duration can collect proximity contact data that allows agent-based models to produce a reasonable estimation of the attack rate. However, higher-resolution data are preferred for modeling individual infection risk. Findings from this part of the dissertation represent a step towards providing the empirical basis for guidelines to inform data collection that is at once efficient and effective.
This dissertation addresses the problem of informing transmission models with proximity contact data in three steps. Firstly, the demonstration of an EKF-SD-SIR model suggests that the filtering approach could improve System Dynamics transmission models by leveraging proximity contact data. In addition, experiments with the EKF-SD-SIR model also revealed that the filtering approach is constrained by the limited quality and reliability of sensing-data-inferred proximate contacts. The following two parts of this dissertation investigate spatial-temporal factors that could impact the quality and reliability of sensor-collected proximity contact data. In the second step, the impact of spatial resolution is illustrated by differences between two typical sensing modalities---Bluetooth beaconing versus GPS co-location. Experiments show that, in general, proximity contact data collected with Bluetooth beaconing lead to transmission models with results different from those driven by proximity contact data collected with GPS co-location. Awareness of the differences between sensing modalities can aid researchers in incorporating proximity contact data into transmission models. Finally, in the third step, the impact of temporal resolution is elucidated by investigating the differences between results of transmission models led by proximity contact data collected with varying observation frequencies. These differences led by varying observation frequencies are evaluated under circumstances with alternative assumptions regarding sampling method, disease/pathogen type, and the underlying population. Experiments show that the impact of sensing regimes is influenced by the type of diseases/pathogens and underlying population, while sampling once in a while can be a decent choice across all situations. This dissertation demonstrated the value of a filtering approach to enhance transmission models with sensor-collected proximity contact data, as well as explored spatial-temporal factors that will impact the accuracy and reliability of sensor-collected proximity contact data. Furthermore, this dissertation suggested guidance for future sensor-based proximity contact data collection and highlighted needs and opportunities for further research on sensing-inferred proximity contact data for transmission models
Mobile Ad-Hoc Networks
Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks
Aerial Vehicles
This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space
Smart Wireless Sensor Networks
The recent development of communication and sensor technology results in the growth of a new attractive and challenging area - wireless sensor networks (WSNs). A wireless sensor network which consists of a large number of sensor nodes is deployed in environmental fields to serve various applications. Facilitated with the ability of wireless communication and intelligent computation, these nodes become smart sensors which do not only perceive ambient physical parameters but also be able to process information, cooperate with each other and self-organize into the network. These new features assist the sensor nodes as well as the network to operate more efficiently in terms of both data acquisition and energy consumption. Special purposes of the applications require design and operation of WSNs different from conventional networks such as the internet. The network design must take into account of the objectives of specific applications. The nature of deployed environment must be considered. The limited of sensor nodes� resources such as memory, computational ability, communication bandwidth and energy source are the challenges in network design. A smart wireless sensor network must be able to deal with these constraints as well as to guarantee the connectivity, coverage, reliability and security of network's operation for a maximized lifetime. This book discusses various aspects of designing such smart wireless sensor networks. Main topics includes: design methodologies, network protocols and algorithms, quality of service management, coverage optimization, time synchronization and security techniques for sensor networks
Energy efficiency in short and wide-area IoT technologies—A survey
In the last years, the Internet of Things (IoT) has emerged as a key application context in the design and evolution of technologies in the transition toward a 5G ecosystem. More and more IoT technologies have entered the market and represent important enablers in the deployment of networks of interconnected devices. As network and spatial device densities grow, energy efficiency and consumption are becoming an important aspect in analyzing the performance and suitability of different technologies. In this framework, this survey presents an extensive review of IoT technologies, including both Low-Power Short-Area Networks (LPSANs) and Low-Power Wide-Area Networks (LPWANs), from the perspective of energy efficiency and power consumption. Existing consumption models and energy efficiency mechanisms are categorized, analyzed and discussed, in order to highlight the main trends proposed in literature and standards toward achieving energy-efficient IoT networks. Current limitations and open challenges are also discussed, aiming at highlighting new possible research directions
Performance Evaluation of Wireless Communication in a Modular Heliostat Field.
Thesis (MEng)--Stellenbosch University, 2021.ENGLISH ABSTRACT: Concentrating Solar Thermal (CST) is differentiated from other renewable energy
technologies by the ability to store large amounts of thermal energy cost-effectively.
CST, and especially Central Receiver Systems (CRS), still require further develop-
ment to drive down the Levelised Cost of Electricity (LCOE) to remain economi-
cally competitive in the renewable energy market.
Heliostats are used in CRS to reflect sunlight onto a central receiver. Data trans-
mission is required between a central server and Local Control Units (LCUs) to
enable high precision tracking, over-the-air calibration updates, and swift emer-
gency reaction. Wireless communication technologies have shown both capital cost
and construction time saving potential for CST plants, but practical performance
knowledge of operation in heliostat fields is limited.
The purpose of this study is to evaluate the feasibility of wireless communica-
tion within a CST field b y m eans o f p ractical t ests a imed t o d etermine t he influ-
ence of interference, dense networks, and transmission range on the network per-
formance. The project forms part of the H2020 PREMA project, which aims to
advance novel energy systems in the drying and pre-heating of furnace manganese
ore.
A communication network consisting of 50 LCUs, capable of controlling 300
heliostats, was designed and implemented to simulate data transmission in a CST
network. Performance experiments were conducted at the Helio100 site to de-
termine the effect of various performance limiting factors. Experimental results
showed a high performing, robust wireless communication system with a worst-
case polling rate of 0.79 s, which satisfies a m ajor r equirement o f t he communi-
cation network. The thesis concludes that wireless communication is feasible in a CST field, which could lead to the reduction of capital costs and construction time,
reducing the LCOE of CST plants.AFRIKAANSE OPSOMMING: Gekonsentreerde Sonkrag (GSK) word onderskei van ander hernubare energie
tegnologieë deur die vermoë om groot hoeveelhede termiese energie koste effektief
te stoor. Gekonsentreerde sonkrag, en veral sentrale ontvangersisteme, benodig nog
verdere ontwikkeling om die gelykte koste van elektrisiteit te verlaag om ekonomies
kompeterend te bly in die hernubare energie mark.
Heliostate word in sentrale ontvangersisteme gebruik om sonlig op ’n sentrale
ontvanger te weerkaats. Data-oordrag is nodig tussen ’n sentrale bediener en plaas-
like beheer eenhede om hoë akkuraatheid volgingsbeweging, oor die lug kalibrasie-
opdaterings en vinnige noodreaksie moontlik te maak. Draadlose kommunikasie-
tegnologie het die potensiaal vir kapitaal kostebesparings en konstruksie tydbespa-
rings vir GSK-aanlegte getoon, maar praktiese kennis oor die netwerk gedrag in
heliostaat velde is beperk.
Die doel van hierdie studie is om die uitvoerbaarheid van draadlose kommunika-
sie binne ’n sentrale ontvangersisteem te evalueer aan die hand van praktiese toetse
om die invloed van interferensie, digte netwerke en die transmissie afstand, op die
netwerk werking te bepaal. Die projek vorm deel van die H2020 PREMA-projek,
wat streef om nuwe energie stelsels te bevorder vir die droog en voorverhitting pro-
ses van mangaanerts.
’n Kommunikasienetwerk bestaande uit 50 plaaslike beheer eenhede, wat 300
heliostate kan beheer, is ontwerp en geïmplementeer om data-oordrag in ’n gekon-
sentreerde sonkrag netwerk te simuleer. ’n Eksperimentele ondersoek is op die
Helio100-terrein gedoen om die effek van verskillende netwerk beperkende faktore
te bepaal. Eksperimentele resultate toon ’n hoë prestasie, robuuste draadlose kommuni-
kasiestelsel wat, in die slegste geval, die hele netwerk binne 0.79 s kan bedien en
so ’n hoofvereiste van die kommunikasie netwerk bevredig. Die tesis het tot die
gevolgtrekking gekom dat draadlose kommunikasie binne ’n GSK heliostaat veld
uitvoerbaar is en dat dit moontlik tot ’n verlaging in kapitaal koste en konstruksie
tyd in sentrale ontvangersisteme kan lei en die gelykte koste van elektrisiteit van
gekonsentreerde sonkrag aanlegte kan verminder.Master
Enabling intuitive and efficient physical computing
Making tools for technology accessible to everyone is important for diverse and inclusive innovation. Significant effort has already been made to make software innovation more accessible, and this effort has created a movement of citizen developers. These citizen developers have the drive to create, but not necessarily the technical skill to innovate with technology. Software, however, has limited impact in the real world compared to hardware and here, physical computing is democratising access to technological innovation. Using microcontroller programming and networking, citizens can now build interactive devices and systems that respond to the real world. But building a physical computing device is riddled with complexity. Memory efficient but hard to use low-level programming languages are used to program microcontrollers, implementation efficient but hard to use wired protocols are used to compose microcontrollers and peripherals, and energy efficient but hard to configure wireless protocols are used to network devices to each other and to the Internet. This consistent trade off between efficiency and ease of use means that physical computing is inaccessible to some. This thesis seeks to democratise microcontroller programming and networking in order to make physical computing accessible to all. It provides a deep exploration of three areas fundamental to physical computing: programming, hardware composition, and wireless networking, drawing parallels with consumer technologies throughout. Based upon these parallels, it presents requirements for each area that may lead to a more intuitive physical computing experience. It uses these requirements to compare existing work in the space and concludes that no existing technology correctly strikes the balance between efficient operation for microcontrollers and intuitive experiences for citizen developers. It therefore goes onto describe and evaluate three new technologies designed to make physical computing accessible to everyone
Contributions to bluetooth low energy mesh networks
Bluetooth Low Energy (BLE) has become a popular Internet of Things (IoT) technology. However, it was originally designed to only support the star topology. This PhD thesis investigates and evaluates different Bluetooth Low Energy (BLE) mesh network approaches, including existing ones (such as the Bluetooth Mesh standard), and our own solution for IPv6-based BLE mesh networking (6BLEMesh). The thesis comprises 6 main contributions:
1.- A comprehensive survey on existing BLE mesh networking proposals and a taxonomy for BLE mesh network solutions.
2.- An energy consumption model for Bluetooth Mesh. The model allows to predict useful performance parameters, such as device average current consumption, device lifetime and energy efficiency, considering the impact of the most relevant Bluetooth Mesh parameters, i.e. PollTimeout and ReceiveWindow, as well as application parameters (e.g. the data interval for a sensor that periodically reports its readings).
3.- A new proposed IPv6-based BLE mesh networking IETF standard (in progress), called 6BLEMesh. After defining the characteristics and properties of 6BLEMesh, we evaluated it in terms of connectivity, latency, RTT, and energy consumption.
4.- For the connectivity evaluation of 6BLEMesh, we developed an analytical model that takes a set of network and scenario characteristics as inputs, and provides two main results: i) the probability of no isolation of a node, and ii) the k-connectivity of the considered network. We validated the model by simulation.
5.- An implementation, and an experimental evaluation, of 6BLEMesh. We built a three-node testbed consisting of all node types (i.e. 6LN, 6LR and 6LBR). We used three different popular commercial hardware platforms. We evaluated a number of performance parameters on the testbed, related with latency and energy consumption. Next, we characterized the current consumption patterns of the complete life cycle for different node types in the three-node testbed. We also evaluated the energy performance of a 6LN on three different platforms. We presented a 6LN current consumption model for different connInterval settings. To this end, we experimentally characterized each current consumption state in terms of its duration time and average current consumption value. We illustrated the impact of connInterval on energy performance.
6.- A comparison between Bluetooth Mesh and 6BLEMesh, in terms of protocol stack, protocol encapsulation overhead, end-toend latency, energy consumption, message transmission count, end-to-end reliability, variable topology robustness and Internet connectivity. Bluetooth Mesh and 6BLEMesh offer fundamentally different BLE mesh networking solutions. Their performance depends significantly on their parameter configuration. Nevertheless, the following conclusions can be obtained. Bluetooth Mesh exhibits slightly greater protocol encapsulation overhead than 6BLEmesh. Both Bluetooth Mesh and 6BLEMesh offer flexibility to configure per-hop latency. For a given latency target, 6BLEMesh offers lower energy consumption. In terms of message transmission count, both solutions may offer relatively similar performance for small networks; however, BLEMesh scales better with network size and density. 6BLEMesh approaches ideal packet delivery probability in the presence of bit errors for most parameter settings (at the expense of latency increase), whereas Bluetooth Mesh requires path diversity to achieve similar performance. Bluetooth Mesh does not suffer the connectivity gaps experimented by 6BLEMesh due to topology changes.
Finally, 6BLEMesh naturally supports IP-based Internet connectivity, whereas Bluetooth Mesh requires a protocol translation gateway.Bluetooth Low Energy (BLE) ha esdevingut una tecnologia popular per a Internet of Things (loT). Ara bé, va ser originalment dissenyada per suportar només la topologia en estrella. Aquesta tesi doctoral investiga i avalua diferents alternatives de xarxa mesh BLE, incloent alternatives existents (com l'estandard Bluetooth Mesh), i la nostra propia solució basada en IPv6, 6BLEMesh. Aquesta tesi comprén 6 contribucions·principals: 1.- Una revisió exhaustiva de l'estat de l'art i una taxonomia de les xarxes mesh BLE. 2.- Un model de consum d'energia per Bluetooth Mesh. El model permet predir parametres de rendiment útils, tals com consum de corrent, temps de vida del dispositiu i eficiéncia energética, considerant !'impacte deis principals parametres de Bluetooth Mesh (PollTimeout i ReceiveWindow) i a nivell d'aplicació. 3.- Un nou estandard (en progrés) anomenat 6BLEMesh. Després de definir les característiques de 6BLEMesh, aquesta solució ha estat avaluada en termes de connectivitat, laténcia, RTT i consum d'energia. 4.- Per a l'avaluació de connectivitat de 6BLEMesh, hem desenvolupat un model analític que proporciona dos resultats principals: i) probabilitat de no arllament d'un node i ii) k-connectivitat de la xarxa considerada. Hem validat el model mitjani;:ant simulació. .- Una imP.lementació, i una avaluació experimental, de 6BLEMesh. S'ha construrt un testbed de tres nodes, que comprén 5tots els tipus de node principals (6LN, 6LR i 6LBR). S'han usat tres plataformes hardware diferents. S'han avaluat diversos parametres de rendiment en el testbed, relacionats amb laténcia i consum d'energia. A continuació, s'ha caracteritzat els patrons de consum de corren! d'un ciclde de vida complet per als diferents tipus de nodes en el testbed. També s'han avaluat les prestacions d'energia d'un 6LN en tres plataformes diferents. S'ha presenta! un model de consum de corren! d'un 6LN per a diferents valors de connlnterval. Per aquest fi, s'ha caracteritzat emplricament cada estat de consum de corrent en termes de la seva durada i consum de corrent. 6.- Una comparativa entre Bluetooth Mesh i 6BLEMesh, en termes de pila de protocols, overhead d'encapsulament de protocol, laténcia extrem a extrem, consum d'energia, nombre de missatges transmesos, fiabilitat extrem a extrem, robustesa davant de topologies variables, i connexió a Internet. Bluetooth Mesh i 6BLEMesh són solucions de BLE mesh networking fonamentalment diferents. Les seves prestacions depenen de la seva configuració de parametres. Ara bé, es poden extreure les següents conclusions. Bluetooth Mesh mostra un overhead d'encapsulament de protocol lleugerament superior al de 6BLEmesh. Tots dos, Bluetooth Mesh i 6BLEMesh, ofereixen flexibilitat per configurar la laténcia per cada salt. Per un target de laténcia doni¡it, 6BLEMesh ofereix un consum d'energia inferior. En termes de nombre de missatges transmesos, les dues solucions ofereixen prestacions relativament similars per a xarxes petites. Ara bé, 6BLEMesh escala millor amb la mida i la densitat de la xarxa. 6BLEMesh s'aproxima a una probabilitat d'entrega de paquets ideal en preséncia d'errors de bit (amb un increment en la laténcia), mentre que Bluetooth Mesh requereix diversitat de caml per assolir unes prestacions similars. Bluetooth Mesh no pateix els gaps de connectivitat que experimenta 6BLLEMesh a causa de canvis en la topología. Finalment, 6BLEMesh suporta de forma natural la connectivitat amb Internet basada en IP, mentre que Bluetooth Mesh requereix un gateway de traducció de protocols.Postprint (published version
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