Contributions to QoS and energy efficiency in wi-fi networks

The Wi-Fi technology has been in the recent years fostering the proliferation of attractive mobile computing devices with broadband capabilities. Current Wi-Fi radios though severely impact the battery duration of these devices thus limiting their potential applications. In this thesis we present a set of contributions that address the challenge of increasing energy efficiency in Wi-Fi networks. In particular, we consider the problem of how to optimize the trade-off between performance and energy effciency in a wide variety of use cases and applications. In this context, we introduce novel energy effcient algorithms for real-time and data applications, for distributed and centralized Wi-Fi QoS and power saving protocols and for Wi-Fi stations and Access Points. In addition, the di¿erent algorithms presented in this thesis adhere to the following design guidelines: i) they are implemented entirely at layer two, and can hence be easily re-used in any device with a Wi-Fi interface, ii) they do not require modi¿cations to current 802.11 standards, and can hence be readily deployed in existing Wi-Fi devices, and iii) whenever possible they favor client side solutions, and hence mobile computing devices implementing them can benefit from an increased energy efficiency regardless of the Access Point they connect to. Each of our proposed algorithms is thoroughly evaluated by means of both theoretical analysis and packet level simulations. Thus, the contributions presented in this thesis provide a realistic set of tools to improve energy efficiency in current Wi-Fi networks

Powering the Internet of Things Through Light Communication

© 2019 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.Novel solutions are required to connect billions of devices to the network as envisioned by the IoT. In this article we propose to use LiFi, which is based on off-the-shelf LEDs, as an enabler for the IoT in indoor environments. We present LiFi4IoT, a system which, in addition to communication, provides three main services that the radio frequency (RF) IoT networks struggle to offer: precise device positioning; the possibility of delivering power, since energy can be harvested from light; and inherent security due to the propagation properties of visible light. We analyze the application space of IoT in indoor scenarios, and propose a LiFi4IoT access point (AP) that communicates simultaneously with IoT devices featuring different types of detectors, such as CMOS camera sensors, PDs, and solar cells. Based on the capabilities of these technologies, we define three types of energy self-sufficient IoT "motes" and analyze their feasibility. Finally, we identify the main research directions to enable the LiFi4IoT vision and provide preliminary results for several of these.Peer ReviewedPostprint (author's final draft

Benchmarking the cooperative awareness service at application layer with IEEE 802.11p and LTE-PC5 Mode-4

© 2021 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. Al document ha d’aparèixer l’enllaç a la publicació original a IEEE, o bé al Digital Object Identifier (DOI).Vehicular communications hold the promise of disrupting mobility services and supporting the mass adoption of future autonomous vehicles. Regulators have set aside specific spectrum at the 5.9 GHz band to support Intelligent Transport Systems (ITS) safety applications, for which a world-wide adoption of a standardized radio technology is a key factor to deliver on this promise. Two technologies are currently positioned to begin its commercial path, IEEE 802.11p and LTE-PC5 Mode-4. The main differences between these technologies lie on the design of their channel access mechanisms. This paper provides an analysis of the impact that the Medium Access Control (MAC) mechanisms included in 802.11p and LTE-PC5 Mode-4 will have on the performance of the applications using the Cooperative Awareness Service, applying two new application-level metrics used by safety applications: Neighborhood Awareness Ratio and Position Error. We have found that, even with an equivalent physical layer performance, the MAC layer of LTE-PC5 Mode-4 will mostly outperform the MAC layer of IEEE 802.11p (or its not yet ready enhanced version 802.11bd). However, IEEE 802.11p/bd results in slightly better vehicle positioning accuracy at lower distances.Peer ReviewedPostprint (author's final draft

SODALITE: SDN wireless backhauling for dense 4G/5G Small Cell networks

© 2019 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.Dense deployments of Small Cells are key to fulfill the capacity requirements of future 5G networks. However, two roadblocks to the adoption of Small Cells are i) the limited availability and the cost of sites with wired backhaul resources, and ii) the complexity to manage a dense deployment of wireless backhaul nodes. Towards these challenges we propose SODALITE, a novel system that applies Software Defined Networking (SDN) to a wireless backhaul network. We present how SODALITE can be integrated to 3GPP’s 4G and 5G architectures, and show the feasibility of SODALITE through LTE network testbed experiments. We substantiate the scalability of SODALITE through stochastic studies using real-life traffic traces from an LTE network and discuss the effects of cell densification and 5G system architecture on these studies. Further, a reliable backhauling solution for wireless links is introduced in SODALITE through SDN-enabled mechanisms that are capable of reconfiguring the data plane upon a link failure detection. Its reliability is shown through experiments on a LTE network testbed, and studied thoroughly via rigorous simulations and network emulator evaluations. As a result, we claim that SODALITE is a promising carrier-grade system to manage a wireless Small Cell backhaul.Postprint (author's final draft

Demo: 5G NR, Wi-Fi and LiFi multi-connectivity for Industry 4.0

The 5G-CLARITY project proposes a novel architecture for private 5G networks that converges Wi-Fi 6, 5G NR and LiFi under a common service platform for Industry 4.0. In this demonstration, we deploy the 5G-CLARITY system in a real factory setup and showcase its multi-connectivity framework, which allows to customize aggregation behavior for different devices. We demonstrate two different aggregation modes. First, a capacity aggregation mode that delivers between 200 Mbps and 600 Mbps to mobile devices throughout the factory floor. Second, a latency-sensitive aggregation mode that is used to replace Ethernet connectivity for a production line achieving endto-end delays below 10 ms

On alleviating cell overload in vehicular scenarios

Fifth Generation (5G) networks will support countless new applications and new business models. One of the 5G paradigms is network slicing, which enables the integration of multiple logical networks each one tailored to the requirements of the different services that can be provided by both network operators and vertical industries. One of the services where 5G is expected to have a greatest impact is vehicular-to-everything (V2X) communications, which will have their stringent latency requirements now met. However, the mobility associated to vehicles can lead to cell overload compromising the required quality of service (QoS). To address this problem, in this paper we propose and evaluate the performance of three network overload alleviation techniques to control network congestion provoked by traffic jams using realistic vehicular traces in a network slicing environment. Firstly, we describe the architecture supporting V2X communications. Secondly, the network congestion control approaches are explained. Finally, after providing a complete description of the considered scenario, results will be detailed, showing that the network overload appearing during rush hour can be significantly reduced.This research was supported by the Spanish Centre for the Development of Industrial Technology (CDTI) and the Ministry of Economy, Industry and Competitiveness under grant/project CER-20191015 / Open, Virtualized Technology Demonstrators for Smart Networks (Open-VERSO).Peer ReviewedPostprint (author's final draft

Novel architecture for cellular IoT in future non-terrestrial networks: store and forward adaptations for enabling discontinuous feeder link operation

© 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 works.The Internet of Things (IoT) paradigm has already progressed from an emerging technology to an incredibly fast-growing field. Defined as one of the three key services in 5th Generation (5G), massive Machine Type Communications (mMTC) are intended to enable the wide-spread adoption of IoT services across the globe. Satellite-based Non-Terrestrial Networks (NTN) are crucial in providing connectivity with global coverage including rural and offshore areas, which are fundamental for supporting important use cases in future networks. A rapidly growing market for IoT devices with mMTC applications using NarrowBandIoT (NB-IoT) will represent a large share of user equipment (UE) in such areas. While standardization efforts for NTN are underway for forthcoming 3GPP releases, they focus on transparent payload architectures where the satellite platform is necessarily connected to a ground station gateway to be able to provide satellite access services to IoT devices, thus requiring complex ground segment infrastructure in low Earth orbit (LEO) constellation deployments to achieve global coverage. In contrast, satellite network deployments targeting the delivery of delay-tolerant IoT applications using NB-IoT, which are a major mMTC use case, can benefit from architectures based on the use of regenerative payloads in the satellite and support for Store and Forward (S&F) operation where satellite access can remain operational even at times when the satellite is not connected to a ground station. In particular, such an approach would allow for extending satellite service coverage in areas where satellites cannot be connected to ground stations (e.g. maritime or very remote areas with lack of ground-stations infrastructures), improving ground segment affordability by enabling operation with fewer ground-stations and allowing more robust operation of the satellite under intermittent feeder link operation. In this paper, we provide a high-level design of an extended 3GPP architecture featuring store and forward mechanisms for IoT NTN delay-tolerant applications that address the previous challenges, as well as a laboratory validation of said architecture for a specific use case.Peer ReviewedPostprint (published version

SENSEFUL: An SDN-based joint access and backhaul coordination for Dense Wi-Fi Small Cells

© 2017 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.Dense Small Cell networks are considered the most effective way to cope with the exponential increase in mobile traffic demand expected for the upcoming years and are one of the foundations of the future 5G. However, novel architectures are required to enable cost-efficient deployments of very dense outdoor Small Cell networks, complementing the coverage layer provided by macro-cells. In this regard, two important challenges need to be solved to make this vision a reality: i) increased traffic dynamics, which are translated into more frequent handovers, and ii) cost-efficient deployment of large number of Small Cells. In this paper we propose and evaluate SENSEFUL, an novel architecture addressing the two problems highlighted above: Software-Defined Networking (SDN) as the key technology to promote adaptability to a varying environment and provide efficient mobility solutions in the dense access layer, and novel wireless backhauling technologies where traditional wired connectivity does not meet cost/efficiency restrictions.Postprint (author's final draft