Contributions to the routing of traffic flows in multi-hop IEEE 802.11 wireless networks

The IEEE 802.11 standard was not initially designed to provide multi-hop capabilities. Therefore, providing a proper traffic performance in Multi-Hop IEEE 802.11 Wireless Networks (MIWNs) becomes a significant challenge. The approach followed in this thesis has been focused on the routing layer in order to obtain applicable solutions not dependent on a specific hardware or driver. Nevertheless, as is the case of most of the research on this field, a cross-layer design has been adopted. Therefore, one of the first tasks of this work was devoted to the study of the phenomena which affect the performance of the flows in MIWNs. Different estimation methodologies and models are presented and analyzed. The first main contribution of this thesis is related to route creation procedures. First, FB-AODV is introduced, which creates routes and forwards packets according to the flows on the contrary to basic AODV which is destination-based. This enhancement permits to balance the load through the network and gives a finer granularity in the control and monitoring of the flows. Results showed that it clearly benefits the performance of the flows. Secondly, a novel routing metric called Weighted Contention and Interference routing Metric (WCIM) is presented. In all analyzed scenarios, WCIM outperformed the other analyzed state-of-the-art routing metrics due to a proper leveraging of the number of hops, the link quality and the suffered contention and interference. The second main contribution of this thesis is focused on route maintenance. Generally, route recovery procedures are devoted to the detection of link breaks due to mobility or fading. However, other phenomena like the arrival of new flows can degrade the performance of active flows. DEMON, which is designed as an enhancement of FB-AODV, allows the preemptive recovery of degraded routes by passively monitoring the performance of active flows. Results showed that DEMON obtains similar or better results than other published solutions in mobile scenarios, while it clearly outperforms the performance of default AODV under congestion Finally, the last chapter of this thesis deals with channel assignment in multi-radio solutions. The main challenge of this research area relies on the circular relationship between channel assignment and routing; channel assignment determines the routes that can be created, while the created routes decide the real channel diversity of the network and the level of interference between the links. Therefore, proposals which join routing and channel assignment are generally complex, centralized and based on traffic patterns, limiting their practical implementation. On the contrary, the mechanisms presented in this thesis are distributed and readily applicable. First, the Interference-based Dynamic Channel Assignment (IDCA) algorithm is introduced. IDCA is a distributed and dynamic channel assignment based on the interference caused by active flows which uses a common channel in order to assure connectivity. In general, IDCA leads to an interesting trade-off between connectivity preservation and channel diversity. Secondly, MR-DEMON is introduced as way of joining channel assignment and route maintenance. As DEMON, MR-DEMON monitors the performance of the active flows traversing the links, but, instead of alerting the source when noticing degradation, it permits reallocating the flows to less interfered channels. Joining route recovery instead of route creation simplifies its application, since traffic patterns are not needed and channel reassignments can be locally decided. The evaluation of MR-DEMON proved that it clearly benefits the performance of IDCA. Also, it improves DEMON functionality by decreasing the number of route recoveries from the source, leading to a lower overhead.El estándar IEEE 802.11 no fue diseñado inicialmente para soportar capacidades multi-salto. Debido a ello, proveer unas prestaciones adecuadas a los flujos de tráfico que atraviesan redes inalámbricas multi-salto IEEE 802.11 supone un reto significativo. La investigación desarrollada en esta tesis se ha centrado en la capa de encaminamiento con el objetivo de obtener soluciones aplicables y no dependientes de un hardware específico. Sin embargo, debido al gran impacto de fenómenos y parámetros relacionados con las capas físicas y de acceso al medio sobre las prestaciones de los tráficos de datos, se han adoptado soluciones de tipo cross-layer. Es por ello que las primeras tareas de la investigación, presentadas en los capítulos iniciales, se dedicaron al estudio y caracterización de estos fenómenos. La primera contribución principal de esta tesis se centra en mecanismos relacionados con la creación de las rutas. Primero, se introduce una mejora del protocolo AODV, que permite crear rutas y encaminar paquetes en base a los flujos de datos, en lugar de en base a los destinos como se da en el caso básico. Esto permite balacear la carga de la red y otorga un mayor control sobre los flujos activos y sus prestaciones, mejorando el rendimiento general de la red. Seguidamente, se presenta una métrica de encaminamiento sensible a la interferencia de la red y la calidad de los enlaces. Los resultados analizados, basados en la simulación de diferentes escenarios, demuestran que mejora significativamente las prestaciones de otras métricas del estado del arte. La segunda contribución está relacionada con el mantenimiento de las rutas activas. Generalmente, los mecanismos de mantenimiento se centran principalmente en la detección de enlaces rotos debido a la movilidad de los nodos o a la propagación inalámbrica. Sin embargo, otros fenómenos como la interferencia y congestión provocada por la llegada de nuevos flujos pueden degradar de forma significativa las prestaciones de los tráficos activos. En base a ello, se diseña un mecanismo de mantenimiento preventivo de rutas, que monitoriza las prestaciones de los flujos activos y permite su reencaminamiento en caso de detectar rutas degradadas. La evaluación de esta solución muestra una mejora significativa sobre el mantenimiento de rutas básico en escenarios congestionados, mientras que en escenarios con nodos móviles obtiene resultados similares o puntualmente mejores que otros mecanismos preventivos diseñados específicamente para casos con movilidad. Finalmente, el último capítulo de la tesis se centra en la asignación de canales en entornos multi-canal y multi-radio con el objetivo de minimizar la interferencia entre flujos activos. El reto principal en este campo es la dependencia circular que se da entre la asignación de canales y la creación de rutas: la asignación de canales determina los enlaces existentes la red y por ello las rutas que se podrán crear, pero son finalmente las rutas y los tráficos activos quienes determinan el nivel real de interferencia que se dará en la red. Es por ello que las soluciones que proponen unificar la asignación de canales y el encaminamiento de tráficos son generalmente complejas, centralizadas y basadas en patrones de tráfico, lo que limita su implementación en entornos reales. En cambio, en nuestro caso adoptamos una solución distribuida y con mayor aplicabilidad. Primero, se define un algoritmo de selección de canales dinámico basado en la interferencia de los flujos activos, que utiliza un canal común en todos los nodos para asegurar la conectividad de la red. A continuación, se introduce un mecanismo que unifica la asignación de canales con el mantenimiento preventivo de las rutas, permitiendo reasignar flujos degradados a otros canales disponibles en lugar de reencaminarlos completamente. Ambas soluciones demuestran ser beneficiosas en este tipo de entornos.Postprint (published version

Design of a UMTS/GPRS Assisted Mesh Network (UAMN)

Wireless Mesh or multi-hop networks (WMNs) are well known thanks to its simplicity on deployment and the lack of infrastructure. These two advantages come with some drawbacks. WMNs have limitations with the support of Quality of Service (QoS), they do not assure coverage or even connectivity, and security, management and monitoring are not considered key requirements. In order to benefit of mesh networks and use them as an operator graded network, it is necessary to either improve mesh networks to fulfill all these requirements or use an alternative network that offers full availability, connectivity and security to assist the mesh network. Considering the two options, the second is the one selected making use of GPRS/UMTS as an assistant network. The document describes a set of requirements and the design of the functionalities needed to build an operator graded network using the cellular GPRS/UMTS. The aspects covered in the design are: security, quality of service, mobility, self configuration and optimization. The last point, optimization, is not directly involved with mesh networking, but it is an improvement easy to achieve when using a gateway node to access the Internet through a GPRS/UMTS connection. The design of the solution not only considers functionality, but also feasibility employing of the shelve elements. The mesh nodes and gateways are built on top of Linux operating system with the aim to reuse previous results and open source software. The final objective of the project is to build a usable system to be used as a proof of concept.Peer Reviewe

Misio kritikorako MCPTT zerbitzuaren integrazioa 5G-NFV ertzeko konexio-sare batean

5G teknologiaren helburu handienetako bat da egungo komunikazio-ekosistema hobetzea. Helburu hori lortzeko, etorkizun handiko irtenbidea da ertzeko konexio-sareen erabilpena, batez ere misio kritikoko zerbitzuak erabiltzen direnean, ertzeko konexio-sareek konputazio-mailan eta komunikazio-trukeari dagokion abiaduran ekartzen dituzten garapenak baliatu ahal izatean. Testu hau MCPTT zerbitzuan ardaztuko da; hau da, gaur egungo larrialdi-talde koordinatuei ahots-komunikazio klasikoa eskaintzen dion horretan. MCPTT zerbitzua 5G ekosisteman integratzearen erronka nagusiak zerikusia du horren funtzionamenduaren orkestrazioarekin, hain zuzen ere MCPTT zerbitzuak sareko azpiegitura beste hainbat zerbitzu eta sareko operadorerekin partekatu behar baitu. Artikulu honetan, software bidez definitutako sare-funtzioak eta sare-funtzioak birtualizatzeko estandar teknologikoak konbinatzen dituen arkitektura bat proposatzen da, 5G estandarrarekin bat datorrena. Ertzeko cluster batean, slicing sareko arkitekturaren birtualizazio-mekanismoa erabiliz, MCPTT zerbitzua nola hedatu den ere azaltzen da. Zehazki, MCPTT sareko funtzio birtuala osatzen duten unitateak deskribatzen dira. Bestalde, sistema osoaren orkestrazioa alertak arintzeko modulu batekin batera lan egiten duen monitorizazio-sistema batean oinarritzen da. Monitorizazio-sistemak zerbitzuaren eragiketarekin, baliabideen erabilerarekin edota irrati bidezko sarbidearen operazioarekin zerikusia duten hainbat parametro jaso eta biltzen ditu denbora errealean, eta, irakurritako balioen arabera, bi alerta mota eman ditzake: batetik, baliabide birtualei dagozkienak bereizten dira, eta, bestetik, irrati-baliabideei eragiten dietenak. Azkenik, MCPTT zerbitzua hedatu ondoren lortutako emaitzak ere aurkezten dira. Horretarako, lehenik eta behin, zerbitzuaren funtzionamendua dinamikoki doitzeko erabili diren monitorizazio-metrikak deskribatzen dira, eta, jarraian, sistemaren probak gauzatzeko zehaztutako agertokiak aurkezten dira. Emaitzen arabera, sistemak agertokietako eskaerei espero bezala erantzuten diela eta bere funtzionamendua dinamikoki ondo egokitzen duela frogatu da.; One of the major objectives of 5G technology is to improve the current communication ecosystem. The use of edge networking is a promising solution to this goal, especially when critical mission services are used. This text will focus on MCPTT, a service that provides a coordinated emergency team with classic voice communication. The main challenge in integrating the MCPTT service into the 5G ecosystem relates to the orchestration of its operation, as the MCPTT service has to share the network infrastructure with many other services and network operators. This paper presents an architecture that is in accordance with the 5G standard and at the same time combines software-defined networking and network functions virtualization. It also shows how MCPTT service has been deployed in a data center located at the edge, by using the slicing network architecture virtualization mechanism. Specifically, the units that constitute the MCPTT virtual network function are described. The orchestration of the entire system is based on a monitor system that works in conjunction with an alert module. The monitoring system receives in real time and gathers a number of parameters related to service operation, use of resources, and operation of radio access, and may provide two types of alert according to the values read: on the one hand, those related to virtual resources, and, on the other, those alerts affecting radio resources. Results obtained after deploying the MCPTT service are also presented. For this purpose, first, the monitoring metrics used to dynamically adjust the operation of the service are described, and then the defined testing scenarios are presented. Results show that the system responds as expected to the different demands of the scenarios, and also that it dynamically adjusts its functioning properly

Weighted contention and interference routing metric (WCIM): Research Report

Contention- and Interference-Aware Flow-based Routing in Wireless Mesh Networks: design and evaluation of a novel routing metric Report 1: Analysis of WCIM model Report 2: SimulationsPreprin

Contention- and interference-aware flow-based routing in wireless mesh networks: design and evaluation of a novel routing metric

As the popularity of IEEE 802.11-based Wireless Mesh Networks (WMNs) grows, end users of these environments demand better performance and quality of service (QoS). However, the Medium Access Control (MAC) layer of the IEEE 802.11 standard was not initially designed to provide either multihop or QoS capabilities. Therefore, the performance of IEEE 802.11-based WMNs is not optimal. One approach that can mitigate the limitations of IEEE 802.11-based WMNs relies on routing flows through appropriate paths according to: (i) the characteristics of the flows, (ii) the quality of the WMN links, (iii) the contention in transmission, and (iv) the interference in reception. Considerable research effort has been devoted to this topic. However, as we argue in this paper, a comprehensive solution is still needed. This paper presents the Weighted Contention and Interference routing Metric (WCIM). Extensive simulation results show that WCIM outperforms state-of-the-art solutions.Peer Reviewe

Weighted contention and interference routing metric (WCIM): Research Report

Contention- and Interference-Aware Flow-based Routing in Wireless Mesh Networks: design and evaluation of a novel routing metric Report 1: Analysis of WCIM model Report 2: Simulation

Cooperative intelligent transport systems for vulnerable road users safety

Cooperative-Intelligent Transport Systems (C-ITS) are one of the flagships of new coming automotive and communication industries. Mobility needs to be safer and more efficient and C-ITS are the key for this new era. On the one hand, organizations like ETSI, IEEE, SAE, 3GPP or ISO are developing the standards for the new technologies and protocols and, on the other, manufacturers and operators are deploying and testing their first pilots. In this paper, we present a pilot developed by a group of stakeholders, in which vehicles will alert drivers of potential collisions with vulnerable road users riding bicycles. It is a multidisciplinary project where there are different architecture components: C-ITS stations integrated in vehicles, vehicles provided with digital cockpits that show warning messages to the driver, low-cost C-ITS stations attached to bicycles which are equipped with a high precision location system based on the fusion of different information sources as GPS, inertial sensors and Ultra Wide Band ranging and finally communication between C-ITS stations is provided by a network that supports low delay C-V2X communications with a Multi-access Edge Computing which takes routing decisions.Peer ReviewedPostprint (published version

Demonstration and evaluation of precise positioning for connected and automated mobility services

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksCooperative, Connected and Automated Mobility (CCAM) services require precise and reliable localization services able to infer and track the position of a vehicle with lane accuracy. The H2020 5GCroCo project, which trials 5G technologies in the European cross-border corridor along France, Germany and Luxembourg, as well as in five small-scale trial sites, considers different technologies to enhance vehicle localization, including GPS-Real Time Kinematic (GPS-RTK), Ultra-WideBand (UWB) and Inertial Sensors (INS). This paper presents a compact prototype, which integrates these localization technologies with 5GCroCo’s On-Board Unit (OBU) equipment, and its evaluation within the scope of the Anticipated Cooperative Collision Avoidance (ACCA) Use Case demonstrated in Barcelona small-scale trial site.This work has been supported by the EC under grant agreement No. 825050 (5GCroCo), by the European Union Regional Development Fund (ERDF) through project Fem IoT and by MCIN/AEI/10.13039/501100011033 under grant PID2020-112675RB-C43. The realization of the trial has been supported by Barcelona’s Institut Municipal d’InformaticaPeer ReviewedPostprint (published version

Redes de comunicaciones : de la telefonía móvil a Internet

Descripció del recurs: 2 de maig de 2012Vivimos completamente rodeados por una miríada de dispositivos electrónicos interconectados, que a su vez originan nuevos servicios y nuevas formas de entender y establecer las relaciones sociales. Nuevas palabras y conceptos acompañan inexorablemente dichos avances. Un progreso que, en muchas ocasiones, implica profundas reflexiones y ciertas dosis de incomprensión: ¿Cómo funcionan tales dispositivos? ¿Cómo es posible la conexión con las antípodas de forma tan simple? Este libro pretende dar respuestas a tales cuestiones, utilizando conceptos básicos de las telecomunicaciones y desafiando al lector a afrontar los retos tecnológicos de las comunicaciones

Design of a UMTS/GPRS Assisted Mesh Network (UAMN)

Wireless Mesh or multi-hop networks (WMNs) are well known thanks to its simplicity on deployment and the lack of infrastructure. These two advantages come with some drawbacks. WMNs have limitations with the support of Quality of Service (QoS), they do not assure coverage or even connectivity, and security, management and monitoring are not considered key requirements. In order to benefit of mesh networks and use them as an operator graded network, it is necessary to either improve mesh networks to fulfill all these requirements or use an alternative network that offers full availability, connectivity and security to assist the mesh network. Considering the two options, the second is the one selected making use of GPRS/UMTS as an assistant network. The document describes a set of requirements and the design of the functionalities needed to build an operator graded network using the cellular GPRS/UMTS. The aspects covered in the design are: security, quality of service, mobility, self configuration and optimization. The last point, optimization, is not directly involved with mesh networking, but it is an improvement easy to achieve when using a gateway node to access the Internet through a GPRS/UMTS connection. The design of the solution not only considers functionality, but also feasibility employing of the shelve elements. The mesh nodes and gateways are built on top of Linux operating system with the aim to reuse previous results and open source software. The final objective of the project is to build a usable system to be used as a proof of concept.Peer Reviewe