Next-Generation Self-Organizing Networks through a Machine Learning Approach

Fecha de lectura de Tesis Doctoral: 17 Diciembre 2018.Para reducir los costes de gestión de las redes celulares, que, con el tiempo, aumentaban en complejidad, surgió el concepto de las redes autoorganizadas, o self-organizing networks (SON). Es decir, la automatización de las tareas de gestión de una red celular para disminuir los costes de infraestructura (CAPEX) y de operación (OPEX). Las tareas de las SON se dividen en tres categorías: autoconfiguración, autooptimización y autocuración. El objetivo de esta tesis es la mejora de las funciones SON a través del desarrollo y uso de herramientas de aprendizaje automático (machine learning, ML) para la gestión de la red. Por un lado, se aborda la autocuración a través de la propuesta de una novedosa herramienta para una diagnosis automática (RCA), consistente en la combinación de múltiples sistemas RCA independientes para el desarrollo de un sistema compuesto de RCA mejorado. A su vez, para aumentar la precisión de las herramientas de RCA mientras se reducen tanto el CAPEX como el OPEX, en esta tesis se proponen y evalúan herramientas de ML de reducción de dimensionalidad en combinación con herramientas de RCA. Por otro lado, en esta tesis se estudian las funcionalidades multienlace dentro de la autooptimización y se proponen técnicas para su gestión automática. En el campo de las comunicaciones mejoradas de banda ancha, se propone una herramienta para la gestión de portadoras radio, que permite la implementación de políticas del operador, mientras que, en el campo de las comunicaciones vehiculares de baja latencia, se propone un mecanismo multicamino para la redirección del tráfico a través de múltiples interfaces radio. Muchos de los métodos propuestos en esta tesis se han evaluado usando datos provenientes de redes celulares reales, lo que ha permitido demostrar su validez en entornos realistas, así como su capacidad para ser desplegados en redes móviles actuales y futuras

Methods for Self-Healing based on traces and unsupervised learning in Self-Organizing Networks

With the advent of Long-Term Evolution (LTE) networks and the spread of a highly varied range of services, mobile operators are increasingly aware of the need to strengthen their maintenance and operational tasks in order to ensure a quality and positive user experience. Furthermore, the co- existence of multiple Radio Access Technologies (RAT), the increase in the traffic demand and the need to provide a great variety of services are steering the cellular network toward a new scenario where management tasks are becoming increasingly complex. As a result, mobile operators are focusing their efforts to deal with the maintenance of their networks without increasing either operational expenditures (OPEX) or capital expenditures (CAPEX). In this context, it is becoming necessary to effectively automate the management tasks through the concept of the Self-Organizing Networks (SON). In particular, SON functions cover three different areas: Self-Configuration, Self-Optimization and Self- Healing. Self-Configuration automates the deployment of new network elements and their parameter configuration. Self-Optimization is in charge of modifying the configuration of the parameters in order to enhance user experience. Finally, Self-Healing aims reduce the impact that failures and services degradation have on the end-user. To that end, Self-Healing (SH) systems monitor the network elements through several alarms, measurements and indicators in order to detect outage and degraded cells, then, diagnose the cause of their problem and, finally, execute the compensation or recovery actions. Even though mobile networks are become more prone to failures due to their huge increase in complexity, the automation of the troubleshooting tasks through the SH functionality has not been fully realized. Traditionally, both the research and the development of SON networks have been related to Self-Configuration and Self-Optimization. This has been mainly due to the challenges that need to be faced when SH systems are studied and implemented. This is especially relevant in the case of fault diagnosis. However, mobile operators are paying increasingly more attention to self-healing systems, which entails creating options to face those challenges that allow the development of SH functions. On the one hand, currently, the diagnosis continues to be manually done since it requires considerable hard-earned experience in order to be able to effectively identify the fault cause. In particular, troubleshooting experts thoroughly analyze the performance of the degraded network elements by means of measurements and indicators in order to identify the cause of the detected anomalies and symptoms. Therefore, automating the diagnosis tasks means knowing what specific performance indicators have to be analyzed and how to map the identified symptoms with the associate fault cause. This knowledge is acquired over time and it is characterized by being operator-specific based on their policies and network features. Furthermore, troubleshooting experts typically solve the failures in a network without either documenting the troubleshooting process or recording the analyzed indicators along with the label of the identified fault cause. In addition, because there is no specific regulation on documentation, the few documented faults are neither properly defined nor described in a standard way (e.g. the same fault cause may be appointed with different labels), making it even more difficult to automate the extraction of the expert knowledge. As a result, this a lack of documentation and lack of historical reported faults makes automation of diagnosis process more challenging. On the other hand, when the exact root cause cannot be remotely identified through the statistical information gathered at cell level, drive test are scheduled for further information. These drive tests aim to monitor mobile network performance by using vehicles to personally measure the radio interface quality along a predefined route. In particular, the troubleshooting experts use specialized test equipment in order to manually collect user-level measurements. Consequently, drive test entail a hefty expense for mobile operators, since it involves considerable investment in time and costly resources (such as personal, vehicles and complex test equipment). In this context, the Third Generation Partnership Project (3GPP) has standardized the automatic collection of field measurements (e.g. signaling messages, radio measurements and location information) through the mobile traces features and its extended functionality, the Minimization of Drive Tests (MDT). In particular, those features allow to automatically monitor the network performance in detail, reaching areas that cannot be covered by drive testing (e.g. indoor or private zones). Thus, mobile traces are regarded as an important enabler for SON since they avoid operators to rely on those expensive drive tests while, at the same time, provide greater details than the traditional cell-level indicators. As a result, enhancing the SH functionalities through the mobile traces increases the potential cost savings and the granularity of the analysis. Hence, in this thesis, several solutions are proposed to overcome the limitations that prevent the development of SH with special emphasis on the diagnosis phase. To that end, the lack of historical labeled databases has been addressed in two main ways. First, unsupervised techniques have been used to automatically design diagnosis system from real data without requiring either documentation or historical reports about fault cases. Second, a group of significant faults have been modeled and implemented in a dynamic system level simulator in order to generate an artificial labeled database, which is extremely important in evaluating and comparing the proposed solutions with the state-of- the-art algorithm. Then, the diagnosis of those faults that cannot be identified through the statistical performance indicators gathered at cell level is automated by the analysis of the mobile traces avoiding the costly drive test. In particular, in this thesis, the mobile traces have been used to automatically identify the cause of each unexpected user disconnection, to geo-localize RF problems that affect the cell performance and to identify the impact of a fault depending on the availability of legacy systems (e.g. Third Generation, 3G). Finally, the proposed techniques have been validated using real and simulated LTE data by analyzing its performance and comparing it with reference mechanisms

Self organisation for 4G/5G networks

Nowadays, the rapid growth of mobile communications is changing the world towards a fully connected society. Current 4G networks account for almost half of total mobile traffic, and in the forthcoming years, the overall mobile data traffic is expected to dramatically increase. To manage this increase in data traffic, operators adopt network topologies such as Heterogeneous Networks. Thus, operators can de­ ploy hundreds of small cells for each macro cell, allowing them to reduce coverage hales and/or lack of capacity. The advent of this technology is expected to tremendously increase the number of nodes in this new ecosystem, so that traditional network management activities based on, e.g., classic manual and field trial design approaches are just not be viable anymore. As a consequence, the academic J literature has dedicated a significant amount of effort to Self-Organising Network (SON) algorithms. These solutions aim to bring intelligence and autonomous adaptability into cellular networks, thereby reducing capital and operation expenditures (CAPEX/OPEX). Another aspect to take into account is that, these type of networks generate a large amount of data during their normal operation in the form of control, management and data measurements. This data is expected to increase in SG due to different aspects, such as densification, heterogeneity in layers and technologies, additional control and management complexity in Network Functions Virtualisation (NFV) and Software Defined Network (SDN), and the advent of the Internet of Things (loT), among others. In this context, operators face the challenge of de ­ signing efficient technologies, while introducing new services, reaching challenges in terms networks, which are self-aware, self-adaptive, and intelligent. This dissertation provides a contribution to the design, analysis, and evaluation of SON solutions to improve network opera tor performance, expenses, and users' experience, by making the network more self-adaptive and intelligent. It also provides a contribution to the design of a self-aware network planning tool, which allows to predict the Quality of Service (QoS) offered to end-users, based on data al ­ ready available in the network . The main thesis contributions are divided into two parts. The first part presents a novel functional architecture based on an automatic and self-organised Reinforcement Learning (RL) based approach to model SON functionalities, in which the main task is the self-coordination of different actions taken by different SON functions to be automatically executed in a self-organised realistic Long Term Evolution (LTE) network. The proposed approach introduces a new paradigm to deal with the conflicts genera ted by the concurrent execution of multiple SON functions, revealing that the proposed approach is general enough to modelali the SON functions and their derived conflicts. The second part of the thesis is dedicated to the problem of QoS prediction. In particular, we aim at finding patterns of knowledge from physical layer data acquired from heterogeneous LTE networks. We propose an approach that not only is able to verify the QoS level experienced by the users, through physical layer measurements of the UEs, but it is a lso able to predict it based on measurements collected at different time, and from different regions of the heterogeneous network. We propose then to make predictions independently of the physical location, in order to exploit the experience gained in other sectors of the network, to properly dimension and deploy heterogeneous nodes. In this context, we use Machine Learning (ML) as a tool to allow the network to learn from experience, improving performances, and big data analytics to drive the network from reactive to predictive.Hoy en día, el rápido crecimiento de las comunicaciones móviles está cambiando el mundo hacia una sociedad completamente conectada. Las redes 4G actuales representan casi la mitad del tráfico móvil total, y en los próximos años se espera que el tráfico total de los dispositivos móviles aumente drásticamente. Para gestionar este incremento de tráfico de datos, los operadores adoptan tecnologías de redes como las redes heterogéneas. De esta manera, los operadores pueden desplegar centena res de pequeñas celdas por cada macro celda, permitiendo reducir zonas sin cobertura y/o falta de capacidad. Con la introducción de esta tecnología, se espera que incremente de manera sustancia l el número de nodos en el nuevo ecosistema, de manera que las actividades de gestión de las redes tradicionales, basadas en, por ejemplo, el diseño manual, sean inviables. Como consecuencia, la literatura académica ha dedicado un esfuerzo significativo al diseño de algoritmos de redes auto-organizadas (SON). Estas soluciones tienen como objetivo introducir inteligencia y capacidad autónoma a las redes móviles, reduciendo la capacidad y costes operativos. Otro aspecto a tener en cuenta es que este tipo de redes generan una gran cantidad de datos durante su funcionamiento habitual, en forma de medidas de control y gestión de datos. Se espera que estos datos incrementen con la tecnología SG, debido a diferentes aspectos como los son la densificación de redes heterogéneas, la complejidad adicional en el control y la gestión de la virtualización de las funciones de redes (NFV) y las redes definidas por software (SON), así como la llegada del internet de las cosas (loT), entre otros. En este contexto, los operadores se enfrentan al reto de diseñar tecnologías eficientes, mientras introducen nuevos servicios, consiguiendo objetivos en términos de satisfacción del cliente, en donde el objetivo global del operador es la construcción de redes auto-conscientes, auto-adaptables e inteligentes. Esta tesis ofrece una contribución al diseño y evaluación de soluciones SON para mejorar el rendimiento de las redes, los costes y la experiencia de los usuarios, consiguiendo que la red sea auto-adaptable e inteligente. Así mismo, proporciona una contribución al diseño de una herramienta de planificación de red auto-consciente, que permita predecir la calidad de servicio brindada a los usuarios finales, basada en la explotación de datos disponibles en la red.Avui en dia, el ràpid creixement de les comunicacions mòbils està canviant el món cap a una societat completament connectada. Les xarxes 4G actuals representen casi la m trànsit mòbil total, i en els propers anys s’espera que el trànsit total de dades mòbils augmenti dràsticament. Per gestionar aquest increment de trànsit de dades, els operadors adopten topologies de xarxa com ara les xarxes heterogènies (HetNets). D’aquesta manera, els operadors poden desplegar centenars de cel·les petites per a cada cella macro, permetent reduir forats en la cobertura i/o la manca de capacitat. Amb l’arribada d’aquesta tecnologia, s’espera que incrementi enormement el nombre de nodes en el nou ecosistema, de manera que les activitats de gestió de xarxa tradicionals, basades en, per exemple, el disseny manual i els assaigs de camp esdevenen simplement inviables. Com a conseqüència, la literatura acadèmica ha dedicat una quantitat significativa d’esforç als algorismes de xarxa auto organitzada (SON). Aquestes solucions tenen com a objectiu portar la intel·ligència i capacitat d’adaptació autònoma a les xarxes mòbils, reduint el capital i les despeses operatives (CAPES/OPEX). Un altre aspecte a tenir en compte és que aquest tipus de xarxes generen una gran quantitat de dades durant el seu funcionament habitual, en forma de mesuraments de control, gestió i dades. S’espera que aquestes dades incrementin amb la tecnologia 5G, degut a diferents aspectes com ara la densificació, l’heterogeneïtat en capes i tecnologies, la complexitat addicional en el control i la gestió de la virtualització de les funcions de xarxa (NFV) i xarxes definides per software (SDN), i l’adveniment de la internet de les coses (IoT), entre d’altres. En aquest context, els operadors s’enfronten al repte de dissenyar tecnologies eficients, mentre introdueixen nous serveis, aconseguint objectius en termes de satisfacció del client, i on l’objectiu global d’un operador és la construcció de xarxes que són autoconscients, auto-adaptables i intel·ligents. Aquesta tesis ofereix una contribució al disseny, l’anàlisi i l’avaluació de les solucions SON per millorar el rendiment de l’operador de xarxa, les xi despeses i l’experiència dels usuaris, fent que la xarxa sigui més auto-adaptable i intel·ligent. També proporciona una contribució al disseny d’una eina de planificació de xarxa autoconscient, el que permet predir la qualitat de servei (QoS) oferta als usuaris finals, basada en dades ja disponibles a la xarxa. Les contribucions principals d’aquesta tesis es divideixen en dues parts. La primera part presenta una nova arquitectura funcional basada en un aprenentatge per reforç (RL) automàtic i auto-organitzat, enfocat en modelar funcionalitats SON, on la tasca principal és l’auto-coordinació de les diferents accions dutes a terme perles diferents funcions SON a ser executades de forma automàtica en una xarxa Long Term Evolution (LTE) auto-organitzada. L’enfocament proposat introdueix un nou paradigma perfer front als conflictes generats per l’execució simultània de múltiples funcions SON, revelant que l’enfocament proposat és prou general per modelar totes les funcions SON i els seus conflictes derivats. La segona part de la tesis està dedicada al problema de la predicció de la qualitat de servei. En particular, el nostre objectiu és trobar patrons de coneixement a partir de dades de la capa física adquirides de xarxes LTE heterogènies. Proposem un enfocament que no només és capaç de verificar el nivell de QoS experimentat pels usuaris, a través de mesuraments de la capa física dels UEs, sinó que també és capaç de predir-ho basant-se en mesuraments adquirits en diferents instants, i de diferents regions de la xarxa heterogènia. Proposem per tant fer prediccions amb independència de la ubicació física, aprofitant l’experiència adquirida en altres sectors de la xarxa, per dimensionar i desplegar nodes heterogenis correctament. En aquest context, utilitzem l’aprenentatge automàtic (ML) com a eina per permetre que la xarxa aprengui de l’experiència, millorant el rendiment, i l’anàlisi de grans volums de dades per a conduir la xarxa de reactiva a predictiva. Durant l’elaboració d’aquesta tesis, s’han extret dues conclusions principals clau. En primer lloc, destaquem la importància de dissenyar algorismes SON eficients per fer front eficaçment a diversos reptes, com ara la ubicació més adequada de funcions SON i algorismes per resoldre adequadament el problema d’implementació distribuïda o centralitzada, o la solució de conflictes entre funcions SON executades a diferents nodes o xarxes. En segon lloc, en termes d’eines de planificació de xarxes, es poden trobar diferents eines cobrint una àmplia gamma de sistemes i aplicacions orientades a la indústria, així com per a fins d’investigació. En aquest context, les solucions investigades són sotmeses contínuament a canvis importants, on un del principals impulsors és presentar solucions més rentable

Cell fault management using machine learning techniques

This paper surveys the literature relating to the application of machine learning to fault management in cellular networks from an operational perspective. We summarise the main issues as 5G networks evolve, and their implications for fault management. We describe the relevant machine learning techniques through to deep learning, and survey the progress which has been made in their application, based on the building blocks of a typical fault management system. We review recent work to develop the abilities of deep learning systems to explain and justify their recommendations to network operators. We discuss forthcoming changes in network architecture which are likely to impact fault management and offer a vision of how fault management systems can exploit deep learning in the future. We identify a series of research topics for further study in order to achieve this

Crowdsourced Reconstruction of Cellular Networks to Serve Outdoor Positioning: Modeling, Validation and Analysis

Positioning via outdoor fingerprinting, which exploits the radio signals emitted by cellular towers, is fundamental in many applications. In most cases, the localization performance is affected by the availability of information about the emitters, such as their coverage. While several projects aim at collecting cellular network data via crowdsourcing observations, none focuses on information about the structure of the networks, which is paramount to correctly model their topology. The difficulty of such a modeling is exacerbated by the inherent differences among cellular technologies, the strong spatio-temporal nature of positioning, and the continuously evolving configuration of the networks. In this paper, we first show how to synthesize a detailed conceptual schema of cellular networks on the basis of the signal fingerprints collected by devices. We turned it into a logical one, and we exploited that to build a relational spatio-temporal database capable of supporting a crowdsourced collection of data. Next, we populated the database with heterogeneous cellular observations originating from multiple sources. In addition, we illustrate how the developed system allows us to properly deal with the evolution of the network configuration, e.g., by detecting cell renaming phenomena and by making it possible to correct inconsistent measurements coming from mobile devices, fostering positioning tasks. Finally, we provide a wide range of basic, spatial, and temporal analyses about the arrangement of the cellular network and its evolution over time, demonstrating how the developed system can be used to reconstruct and maintain a deep knowledge of the cellular network, possibly starting from crowdsourced information only

Project BeARCAT : Baselining, Automation and Response for CAV Testbed Cyber Security : Connected Vehicle & Infrastructure Security Assessment

Connected, software-based systems are a driver in advancing the technology of transportation systems. Advanced automated and autonomous vehicles, together with electrification, will help reduce congestion, accidents and emissions. Meanwhile, vehicle manufacturers see advanced technology as enhancing their products in a competitive market. However, as many decades of using home and enterprise computer systems have shown, connectivity allows a system to become a target for criminal intentions. Cyber-based threats to any system are a problem; in transportation, there is the added safety implication of dealing with moving vehicles and the passengers within

Artificial Intelligence-based Cybersecurity for Connected and Automated Vehicles

The damaging effects of cyberattacks to an industry like the Cooperative Connected and Automated Mobility (CCAM) can be tremendous. From the least important to the worst ones, one can mention for example the damage in the reputation of vehicle manufacturers, the increased denial of customers to adopt CCAM, the loss of working hours (having direct impact on the European GDP), material damages, increased environmental pollution due e.g., to traffic jams or malicious modifications in sensors’ firmware, and ultimately, the great danger for human lives, either they are drivers, passengers or pedestrians. Connected vehicles will soon become a reality on our roads, bringing along new services and capabilities, but also technical challenges and security threats. To overcome these risks, the CARAMEL project has developed several anti-hacking solutions for the new generation of vehicles. CARAMEL (Artificial Intelligence-based Cybersecurity for Connected and Automated Vehicles), a research project co-funded by the European Union under the Horizon 2020 framework programme, is a project consortium with 15 organizations from 8 European countries together with 3 Korean partners. The project applies a proactive approach based on Artificial Intelligence and Machine Learning techniques to detect and prevent potential cybersecurity threats to autonomous and connected vehicles. This approach has been addressed based on four fundamental pillars, namely: Autonomous Mobility, Connected Mobility, Electromobility, and Remote Control Vehicle. This book presents theory and results from each of these technical directions

Artificial Intelligence-based Cybersecurity for Connected and Automated Vehicles

The damaging effects of cyberattacks to an industry like the Cooperative Connected and Automated Mobility (CCAM) can be tremendous. From the least important to the worst ones, one can mention for example the damage in the reputation of vehicle manufacturers, the increased denial of customers to adopt CCAM, the loss of working hours (having direct impact on the European GDP), material damages, increased environmental pollution due e.g., to traffic jams or malicious modifications in sensors’ firmware, and ultimately, the great danger for human lives, either they are drivers, passengers or pedestrians. Connected vehicles will soon become a reality on our roads, bringing along new services and capabilities, but also technical challenges and security threats. To overcome these risks, the CARAMEL project has developed several anti-hacking solutions for the new generation of vehicles. CARAMEL (Artificial Intelligence-based Cybersecurity for Connected and Automated Vehicles), a research project co-funded by the European Union under the Horizon 2020 framework programme, is a project consortium with 15 organizations from 8 European countries together with 3 Korean partners. The project applies a proactive approach based on Artificial Intelligence and Machine Learning techniques to detect and prevent potential cybersecurity threats to autonomous and connected vehicles. This approach has been addressed based on four fundamental pillars, namely: Autonomous Mobility, Connected Mobility, Electromobility, and Remote Control Vehicle. This book presents theory and results from each of these technical directions

Applications

Volume 3 describes how resource-aware machine learning methods and techniques are used to successfully solve real-world problems. The book provides numerous specific application examples: in health and medicine for risk modelling, diagnosis, and treatment selection for diseases in electronics, steel production and milling for quality control during manufacturing processes in traffic, logistics for smart cities and for mobile communications

On the optimal operation of wireless networks

With the ever increasing mobile traffic in wireless networks, radio frequency spectrum is becoming limited and overcrowded. To address the radio frequency spectrum scarcity problem, researchers proposed advanced radio technology-Cognitive Radio to make use of the uncommonly used and under-utilized licensed bands to improve overall spectrum efficiency. Mobile service providers also deploy small base stations on the streets, into shopping center and users\u27 households in order to improve spectrum efficiency per area. In this thesis, we study cooperation schemes in cognitive radio networks as well as heterogeneous networks to reuse the existing radio frequency spectrum intelligently and improve network throughput and spectrum efficiency, reduce network power consumption and provide network failure protection capability. In the first work of the thesis, we study a multicast routing problem in Cognitive Ratio Networks (CRNs). In this work, all Secondary Users (SUs) are assumed not self interested and they are willing to provide relay service for source SUs. We propose a new network modeling method, where we model CRNs using a Multi-rate Multilayer Hyper-Graph (MMHG). Given a multicast session of the MMHG, our goal is to find the multicast routing trees that minimize the worst case end-to-end delay, maximize the multicast rate and minimize the number of transmission links used in the multicast tree. We apply two metaheuristic algorithms (Multi-Objective Ant Colony System optimization algorithm (MOACS) and Archived Multi-Objective Simulated Annealing Optimization Algorithm (AMOSA)) in solving the problem. We also study the scheduling problem of multicast routing trees obtained from the MMHG model. In the second work of the thesis, we study the cell outage compensation function of the self-healing mechanism using network cooperation scheme. In a heterogeneous network environment with densely deployed Femto Base Stations (FBSs), we propose a network cooperation scheme for FBSs using Coordinated Multi-Point (CoMP) transmission and reception with joint processing technique. Different clustering methods are studied to improve the performance of the network cooperation scheme. In the final work of the thesis, we study the user cooperative multi-path routing solution for wireless Users Equipment (UEs)\u27 streaming application using auction theory. We assume that UEs use multi-path transport layer service, and establish two paths for streaming events, one path goes through its cellular link, another path is established using a Wi-Fi connection with a neighbor UE. We study user coordinated multi-path routing solution with two different energy cost functions (LCF and EAC) and design user cooperative real-time optimization and failure protection operations for the streaming application. To stimulate UEs to participate into the user cooperation operation, we design a credit system enabled with auction mechanism. Simulation results in this thesis show that optimal cooperation operations among network devices to reuse the existing spectrum wisely are able to improve network performance considerably. Our proposed network modeling approach in CRN helps reduce the complicated multicast routing problem to a simple graph problem, and the proposed algorithms can find most of the optimal multicast routing trees in a short amount of time. In the second and third works, our proposed network cooperation and user cooperation approaches are shown to provide better UEs\u27 throughput compared to non-cooperation schemes. The network cooperation approach using CoMP provides failure compensation capability by preventing the system sum rate loss from having the same speed of radio resource loss, and this is done without using additional radio resources and will not have a significant adverse effect on the performance of other UEs. The user cooperation approach shows great advantage in improving service rate, improving streaming event success rate and reducing energy consumption compared to non-cooperation solution