IEEE 802.11 parameters adaptation for Performance enhancement in high density Wireless networks

Tribunal : Ramón Agüero, Álvaro Martín, Federico LarrocaNowadays, it is common to find wireless networks that are based on the IEEE 802.11 standard deployed in an unplanned and unmanaged manner. Moreover, because of the low hardware cost and, trying to obtain optimal coverage and performance, a large number of devices are usually installed in reduced spaces generating high-density deployments. This kind of networks experiment a myriad of problems (e.g., interference, medium access control, etc.) related with the shared nature of the transmission medium. In recent years, different physical-layer- and link-layer-adaptation mechanisms have been proposed to palliate those problems, however, their feedback-loop-based behaviour in a highly complex RF medium makes their performance hard to assess. In this work, we study the problems of high-density networks, experimentally evaluate some existing solutions and propose a new adaptation mechanism, PRCS, that tackles some common weakness of those solutions. PRCS control the transmit power, the data rate, and the carrier sense threshold of APs of a wireless network so as to mitigate the effects of interference in high-density deployments without causing unfairness between links. In simulation-based experiments, PRCS outperforms similar existing mechanisms in various scenarios and in a particular scenario, where most mechanisms fail, duplicates global network throughput.En la actualidad, es muy común encontrar redes inalámbricas basadas en el estándar IEEE 802.11 desplegadas de manera no planificada ni gestionada. Además, debido al bajo costo de los dispositivos y con la intención de obtener una cobertura y rendimiento óptimos, un gran número de dispositivos son instalados en espacios reducidos, generado despliegues de alta densidad. Este tipo de redes experimentan una gran variedad de problemas (por ej., interferencia, control de acceso al medio, etc.) relacionados con el hecho de que utilizan un medio de transmisión compartido. En los últimos años, diferentes mecanismos de adaptación de parámetros de la capa física y de enlace han sido propuestos con el objetivo de mitigar estos problemas. Estas soluciones adaptan parámetros tales como la potencia de transmisión o la tasa de transmisión. En este trabajo, estudiamos los problemas de las redes inalámbricas de alta densidad, evaluamos mediante experimentos algunas de las soluciones existentes y proponemos un nuevo mecanismo de adaptación, PRCS, que aborda algunas de las debilidades de estas soluciones. PRCS controla la potencia de transmisión, la tasa de transmisión y el umbral del mecanismo de sensado de portadora de los puntos de acceso de una red inalámbrica. El objetivo de este mecanismo es mitigar los efectos de la interferencia en despliegues de alta densidad sin causar asimetrías entre los enlaces. En experimentos basados en simulaciones, mostramos que PRCS supera a los mecanismos existentes en varios escenarios y, en un escenario en particular donde la mayoría de los mecanismos fallan, duplica el rendimiento global de la red

Experimenting with routing protocols in the data center : An ns-3 simulation approach

Massive scale data centers (MSDC) have become a key component of current content-centric Internet architecture. With scales of up to hundreds of thousands servers, conveying traffic inside these infrastructures requires much greater connectivity resources than traditional broadband Internet transit networks. MSDCs use Fat-Tree type topologies, which ensure multipath connectivity and constant bisection bandwidth between servers. To properly use the potential advantages of these topologies, specific routing protocols are needed, with multipath support and low control messaging load. These infrastructures are enormously expensive, and therefore it is not possible to use them to experiment with new protocols; that is why scalable and realistic emulation/simulation environments are needed. Based on previous experiences, in this paper we present extensions to the ns-3 network simulator that allow executing the Free Range Routing (FRR) protocol suite, which support some of the specific MSDC routing protocols. Focused on the Border Gateway Protocol (BGP), we run a comprehensive set of control plane experiments over Fat-Tree topologies, achieving competitive scalability running on a single-host environment, which demonstrates that the modified ns-3 simulator can be effectively used for experimenting in the MSDC. Moreover, the validation was complemented with a theoretical analysis of BGP behavior over selected scenarios. The whole project is available to the community and fully reproducible

Resource allocation and management techniques for network slicing in WiFi networks

© 2020 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 works.Network slicing has recently been proposed as one of the main enablers for 5G networks; it is bound to cope with the increasing and heterogeneous performance requirements of these systems. To "slice" a network is to partition a shared physical network into several self-contained logical pieces (slices) that can be tailored to offer different functional or performance requirements. Moreover, a defining characteristic of the slicing paradigm is to provide resource isolation as well as efficient use of resources. In this context, the thesis described in this paper contributes to the problem of slicing WiFi networks by proposing a solution to the problem of enforcing and controlling slices in WiFi Access Points. The focus of the research is on a variant of network slicing called QoS Slicing, in which slices have specific performance requirements. In this document, we describe the two main contributions of our research, a resource allocation mechanism to assign resources to slices, and a solution to enforce and control slices with performance requirements in WiFi Access Points.This work has been supported by the European Commission and the Spanish Government (Fondo Europeo de Desarrollo Regional, FEDER) by means of the EU H2020 NECOS (777067) and ADVICE (TEC2015-71329) projects.Peer ReviewedPostprint (author's final draft

End-to-end KPI analysis in converged fixed-mobile networks

©2020 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 works.The independent operation of mobile and fixed network segments is one of the main barriers that prevents improving network performance while reducing capital expenditures coming from overprovisioning. In particular, a coordinated dynamic network operation of both network segments is essential to guarantee end-to-end Key Performance Indicators (KPI), on which new network services rely on. To achieve such dynamic operation, accurate estimation of end-to-end KPIs is needed to trigger network reconfiguration before performance degrades. In this paper, we present a methodology to achieve an accurate, scalable, and predictive estimation of end-to-end KPIs with sub-second granularity near real-time in converged fixed-mobile networks. Specifically, we extend our CURSA-SQ methodology for mobile network traffic analysis, to enable converged fixed-mobile network operation. CURSA-SQ combines simulation and machine learning fueled with real network monitoring data. Numerical results validate the accuracy, robustness, and usability of the proposed CURSA-SQ methodology for converged fixed-mobile network scenarios.The research leading to these results has received funding from the Spanish MINECO TWINS project (TEC2017-90097-R), and from the Catalan Institution for Research and Advanced Studies (ICREA).Peer ReviewedPostprint (author's final draft

Slicing with guaranteed quality of service in wifi networks

Network slicing has recently been proposed as one of the main enablers for 5G networks. The slicing concept consists of the partition of a physical network into several self-contained logical networks (slices) that can be tailored to offer different functional or performance requirements. In the context of 5G networks, we argue that existing ubiquitous WiFi technology can be exploited to cope with new requirements. Therefore, in this paper, we propose a novel mechanism to implement network slicing in WiFi Access Points. We formulate the resource allocation problem to the different slices as a stochastic optimization problem, where each slice can have bit rate, delay, and capacity requirements. We devise a solution to the problem above using the Lyapunov drift optimization theory, and we develop a novel queuing and scheduling algorithm. We have used MATLAB and Simulink to build a prototype of the proposed solution, whose performance has been evaluated in a typical slicing scenario.This work has been supported in part by the European Commission and the Spanish Government (Fondo Europeo de Desarrollo Regional, FEDER) by means of the EU H2020 NECOS (777067) and ADVICE (TEC2015-71329) projects, respectivel

Near real-time estimation of end-to-end performance in converged fixed-mobile networks

© Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The independent operation of mobile and fixed network segments is one of the main barriers that prevents improving network performance while reducing capital expenditures coming from overprovisioning. In particular, a coordinated dynamic network operation of both network segments is essential to guarantee end-to-end Key Performance Indicators (KPI), on which new network services rely on. To achieve such dynamic operation, accurate estimation of end-to-end KPIs is needed to trigger network reconfiguration before performance degrades. In this paper, we present a methodology to achieve an accurate, scalable, and predictive estimation of end-to-end KPIs with sub-second granularity near real-time in converged fixed-mobile networks. Specifically, we extend our CURSA-SQ methodology for mobile network traffic analysis, to enable converged fixed-mobile network operation. CURSA-SQ combines simulation and machine learning fueled with real network monitoring data. Numerical results validate the accuracy, robustness, and usability of the proposed CURSA-SQ methodology for converged fixed-mobile network scenarios.Peer ReviewedPostprint (author's final draft

Guaranteed bit rate slicing in WiFi networks

In forthcoming 5G networks, slicing has been proposed as a means to partition a shared physical network infrastructure into different self-contained logical parts (slices), which are set up to satisfy certain requirements. Although the topic has been thoroughly investigated by the scientific community and the industry, there are not many works addressing the challenges that appear when trying to exploit slicing techniques over WiFi networks. In this paper, we propose a novel method of allocating resources for WiFi networks to satisfy minimum bit rate requirements. We formulate an optimization problem, and we propose a solution based on the theory of Lyapunov drift optimization. The validity of the proposed solution is assessed by means of a simulation-based evaluation in Matlab.This work has been supported in part by the European Commission and the Spanish Government (Fondo Europeo de Desarrollo Regional, FEDER) by means of the EU H2020 NECOS (777067) and ADVICE (TEC2015-71329) projects, respectively

Slicing in WiFi networks through airtime-based resource allocation

Network slicing is one of the key enabling technologies for 5G networks. It allows infrastructure owners to assign resources to service providers (tenants), which will afterwards use them to satisfy their end-user demands. This paradigm, which changes the way networks have been traditionally managed, was initially proposed in the wired realm (core networks). More recently, the scientific community has paid attention to the integration of network slicing in wireless cellular technologies (LTE). However, there are not many works addressing the challenges that appear when trying to exploit slicing techniques over WiFi networks, in spite of their growing relevance. In this paper we propose a novel method of proportionally distributing resources in WiFi networks, by means of the airtime. We develop an analytical model, which shed light on how such resources could be split. The validity of the proposed model is assessed by means of simulation-based evaluation over the ns-3 framework.This work has been supported in part by the European Commission and the Spanish Government (Fondo Europeo de desarrollo Regional, FEDER) by means of the EU H2020 NECOS (777067) and ADVICE (TEC2015-71329) projects, respectively

Coordination of radio access and optical transport

New 5G and beyond applications demand strict delay requirements. In this paper, we propose coordination between radio access and optical transport to guarantee such delay while optimizing optical capacity allocation. Illustrative results show near real-time autonomous capacity adaptation benefits based on radio access delay requirements.The research leading to these results has received funding from the HORIZON SEASON (G.A. 101096120), the UNICO5G TIMING (TSI-063000-2021-145), and the MICINN IBON (PID2020-114135RB-I00) projects and from the ICREA institution.Peer ReviewedPostprint (author's final draft

Resource allocation and management techniques for network slicing in WiFi networks

Network slicing has recently been proposed as one of the main enablers for 5G networks; it is bound to cope with the increasing and heterogeneous performance requirements of these systems. To "slice'' a network is to partition a shared physical network into several self-contained logical pieces (slices) that can be tailored to offer different functional or performance requirements. Moreover, a key characteristic of the slicing paradigm is to provide resource isolation as well as an efficient use of resources. In this context, a slice is envisioned as an end-to-end virtual network which permits that the infrastructure operators lease their resources to service providers (tenants) through the dynamic, and on-demand, deployment of slices. Tenants may have complete control over the slice functions and resources, and employ them to satisfy their client’s demands. Recent works on slicing for Radio Access Networks (RANs) just focus on general architectures and frameworks for the management and instantiation of network slices avoiding details on how the slices are implemented and enforced in the wireless devices. Even more, while some techniques for slice enforcement already exist, most of them concentrate on cellular technologies, ignoring WiFi networks. Despite of their growing relevance and ubiquity, there are not many works addressing the challenges that appear when trying to apply slicing techniques over WiFi networks. In this scenario, this thesis contributes to the problem of slicing WiFi networks by proposing a solution to enforce and control slices in WiFi Access Points. The focus of this work is on a particular and complex variant of network slicing called QoS Slicing, in which slices have specific performance requirements. The main thesis contributions are divided in three: (1) a detailed analysis of the network slicing problem in RANs in general and in WiFi in particular, as well as a study and definition of the QoS Slicing problem, (2) a resource allocation model and mechanism for Wifi devices, and (3) a QoS Slicing solution to enforce and control slices with performance requirements in WiFi Access Points. Given the novelty of the slicing concept and the complexity of the problem, a detailed study of the slicing problem was performed providing a comprehensive definition of the slicing concept, as well as a classification of the slicing variants. It is also introduced the two main problems of slicing wireless resources: resource allocation and isolation. In the scope of those problems, this thesis contributes with a novel approach where the resource allocation problem is divided on two sub-tasks: Dynamic Resource Allocation, and Enforcement and Control. As a previous step to the construction of a QoS Slicing solution, it is proposed a novel method of proportionally distributing resources in WiFi networks, by means of the airtime. The proposed mechanism (called ATERR) is based on considering the airtime as the wireless resource to be shared and allocated. An analytical model of the ATERR algorithm is also developed, which shed light on how such resources could be split and on the capacities and limitations of the proposal. The validity of the proposed model is assessed by means of a simulation-based evaluation on the NS-3 framework. Finally, regarding the QoS Slicing problem, it is considered two different performance requirements: a guaranteed minimum bit rate and a maximum allowable delay. The resource allocation problem to the different slices is formulated as a stochastic optimization problem, where each slice's requirement of bit rate and delay is modeled as a constraint. A solution to the aforementioned problem is devised using the Lyapunov drift optimization theory to obtain an approximate deterministic problem. With this solution, it is developed a novel queuing and scheduling algorithm which allows implementing the obtained solution in WiFi devices.Network slicing ha estat recentment proposat com un dels aspectes claus de les xarxes 5G i s'espera que permeti afrontar les creixents demandes de rendiment que tindran aquests sistemes. Fer slicing consisteix en fer particions d'una xarxa física compartida en diverses parts (slices) lògiques autocontenidas que poden ser adaptades per oferir diferents requeriments funcionals o de rendiment. Més encara, una característica clau del paradigma de slicing és el de proveir aïllament dels recursos així com permetre un ús eficient dels mateixos. En aquest context, una slice es pot considerar com una xarxa virtual d'extrem a extrem que permet als operadors d'infraestructura arrendar els seus recursos a proveïdors de servei (arrendatari) mitjançant el desplegament dinàmic i sota demanda de slices. Els arrendataris poden tenir control complet sobre els recursos i funcions de la slice i utilitzar-los per satisfer les demandes dels seus clients. Treballs recents sobre slicing en xarxes d'accés sense fil s'han enfocat en arquitectures generals i esquemes de gestió per al desplegament de slicing. En aquest sentit, no s'ha aprofundit en detalls de com s'implementen i controlen les slices en els dispositius sense fils. A més, encara hi ha algunes tècniques per al control de slices, la majoria es concentren en tecnologies per a xarxes mòbils i no tenen en compte les xarxes WiFi malgrat la seva creixent rellevància i omnipresència. En aquest escenari, aquesta tesi contribueix al problema de slicing en xarxes WiFi proposant una solució per implementar i controlar slices en punts d'accés WiFi. El treball es concentra en slicing amb qualitat de servei (QoS Slicing), una variant complexa del problema on les slices tenen requeriments de rendiment específics. Les principals contribucions de la tesi es divideixen en tres: (1) una detallada anàlisi del problema de network slicing en xarxes d'accés sense fil i en particular en WiFi, així com un estudi i definició dels problemes de QoS Slicing, (2) un model i mecanisme per a l'assignació de recursos en dispositius WiFi, i (3) una solució per QoS Slicing que implementa i controla slices amb requeriments de rendiment en punts d'accés WiFi. Donada la novetat del concepte de slicing i la complexitat del problema, es va realitzar un estudi detallat del problema de slicing on es proveeix una definició completa del concepte de slicing. A més, s'introdueixen els dos principals problemes del slicing: l'assignació de recursos i l'aïllament. En aquest sentit, aquesta tesi contribueix amb una estratègia original on el problema d'assignació de recursos es divideix en dues tasques: l'assignació dinàmica de recursos i el control de l'assignació. Com un pas previ a la construcció d'una solució per QoS Slicing, es proposa un mètode original per a la distribució proporcional de recursos en xarxes WiFi mitjançant el control del temps de transmissió. El mecanisme proposat (anomenat ATERR) es basa en considerar el temps de transmissió com el recurs a ser compartit i assignat. També es va desenvolupar un model analític de l'algoritme ATERR del qual es poden obtenir les capacitats i limitacions del mecanisme. La validesa del model proposat és estudiada mitjançant una avaluació basada en simulacions sobre l'entorn NS-3. Finalment, pel que fa al problema de QoS Slicing, es van considerar dos requeriments diferents: una garantia de taxa de transmissió mínima i un màxim de latència permès. El problema d'assignació de recursos per a les diferents slices es va formular com un problema d'optimització estocàstica on els requeriments de cada slice es modelen com una restricció. Es va elaborar una solució al problema anterior utilitzant la teoria d'optimització de Lyapunov per obtenir un problema determinista aproximat. Amb aquesta solució, es va desenvolupar un algoritme d'assignació del temps de transmissió per a dispositius WiFi