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  • Tampere University of Technology

    On the performance of narrow-band internet of things (NB-IoT) for delay-tolerant services

    Citation Mozny, R., Masek, P., Stusek, M., Zeman, K., Ometov, A., & Hosek, J. (2019). On the performance of narrow- band internet of things (NB-IoT) for delay-tolerant services. In N. Herencsar (Ed.), 2019 42nd International Conference on Telecommunications and Signal Processing, TSP 2019 (pp. 637-642). (2019 42nd International Conference on Telecommunications and Signal Processing, TSP 2019). IEEE. https://doi.org/10.1109/TSP.2019.8768871 Year 2019

    Version Peer reviewed version (post-print)

    Link to publication TUTCRIS Portal (http://www.tut.fi/tutcris)

    Published in 2019 42nd International Conference on Telecommunications and Signal Processing, TSP 2019

    DOI 10.1109/TSP.2019.8768871

    Take down policy If you believe that this document breaches copyright, please contact cris.tau@tuni.fi, and we will remove access to the work immediately and investigate your claim.

    Download date:30.05.2020

    https://tutcris.tut.fi/portal/en/persons/aleksandr-ometov(2fa965cc-6ee8-4531-ad2b-88b49b79c078).html https://tutcris.tut.fi/portal/en/publications/on-the-performance-of-narrowband-internet-of-things-nbiot-for-delaytolerant-services(170e76f6-2075-4de5-80ce-35095df73b66).html https://tutcris.tut.fi/portal/en/publications/on-the-performance-of-narrowband-internet-of-things-nbiot-for-delaytolerant-services(170e76f6-2075-4de5-80ce-35095df73b66).html https://doi.org/10.1109/TSP.2019.8768871 https://tutcris.tut.fi/portal/en/publications/on-the-performance-of-narrowband-internet-of-things-nbiot-for-delaytolerant-services(170e76f6-2075-4de5-80ce-35095df73b66).html https://doi.org/10.1109/TSP.2019.8768871

  • On the Performance of Narrow-band Internet of Things (NB-IoT) for Delay-tolerant Services

    Radek Mozny∗, Pavel Masek∗, Martin Stusek∗, Krystof Zeman∗, Aleksandr Ometov†, and Jiri Hosek∗ ∗Department of Telecommunication, Brno University of Technology, Brno, Czech Republic

    †Laboratory of Electronics and Communications Engineering, Tampere University, Tampere, Finland Email: masekpavel@vutbr.cz

    Abstract—Narrowband IoT (NB-IoT) stands for a radio access technology standardized by the 3GPP organization in Release 13 to enable a large set of use-cases for massive Machine-type Communications (mMTCs). Compared to legacy human-oriented 4G (LTE) communication systems, NB-IoT has game-changing features in terms of extended coverage, enhanced power saving modes, and a reduced set of available functionality. At the end of the day, these features allow for connectivity of devices in challenging positions, enabling long battery life and reducing device complexity. This article addresses the development of the universal testing device for delay-tolerant services allowing for in-depth verification of NB-IoT communication parameters. The presented outputs build upon our long-term cooperation with the Vodafone Czech Republic a.s. company.

    Keywords—NB-IoT; IoT, mMTC; LPWAN; Network services

    I. INTRODUCTION

    The Internet of Things, often referred to as IoT, encom- passes the vision of ubiquitous connectivity across the globe. The deployment of IoT, consisting of various types of devices interconnected for communication, is expected to reach a massive scale in the near future. Furthermore, wireless connec- tivity through Low-power Wide-area (LPWAN) networks will be an important component of forthcoming communication scenarios [1]. The estimations from Cisco predicts 12 billion connected devices in 2021 [2]. The vision of Ericsson goes even further and advocates up to 18 billion communicating devices in 2022 [3]. Those predictions lead us to the question, What are the devices that will become connected and are not yet online? Based on the outputs from the available reports, the early-adopters will be in the first deployment phase represented by smart meters (gas, water, electricity) and monitoring devices (smoke sensors and fire alarms) [4]. Therefore, traditional use-cases such as connecting utility meters to support, e.g., distribution and billing, will most likely increase in numbers [5]. Thus, the Industrial IoT sector related to the smart metering opens the door for the delay-tolerant remote reading of the measured data [6], [7].

    The predicted growth of connected devices transmitting Machine-to-Machine (M2M) data is supported, or perhaps even managed, by the recent work performed by the Third

    The described research was supported by the National Sustainability Program under grant LO1401. For the research, the infrastructure of the SIX Center was used. The described research was financed by the Ministry of Industry and Trade of Czech Republic project No. FV20487. This work was supported by the Academy of Finland (project #313039 – PRISMA).

    Generation Partnership Project (3GPP) development organiza- tion in the Release 13 [8]. Based on the requirements given by the IoT vision, the design of new Cellular IoT (CIoT) technologies has been rethought, and a new radio access technologies operating in licensed frequency spectrum have been developed and became available within a very short period of time [9]. The three new technologies targeted to provide communication for IoT in cellular infrastructure are known as: (i) Extended Coverage Global System for Mobile Communications Internet of Things (EC-GSM-IoT), (ii) Long- Term Evolution for Machine-Type Communications Category M1 (LTE Cat-M1), and (iii) Narrowband IoT (NB-IoT).

    A. Narrowband IoT (NB-IoT)

    As the situation evolved, the NB-IoT has became the pre- ferred cellular communication technology for remote metering across the Europe1. NB-IoT is a radio access technology that reuses technical components from its predecessor in some aspects, i.e., Long Term Evolution (LTE) to facilitate operation within licensed LTE frequency spectrum. This technology also supports a stand-alone operation. As the name reveals, the entire system operates in a narrow spectrum, starting from only 200 kHz, providing unprecedented deployment flexibility because of the minimal frequency spectrum requirements in comparison with the legacy LTE. The bandwidth of 200 kHz is divided into channels with 3.75 kHz or 15 kHz spacing to support a combination of extreme coverage and high uplink capacity, considering the narrow spectrum deployment [10].

    While LTE Cat-M1 solely utilizes existing LTE/LTE-A frequencies restricted to 1.4 MHz bandwidth, NB-IoT supports maximum flexibility of the deployment and prepares for re- farming scenarios [11]. Accordingly, NB-IoT is possible to deploy in three modes of operation: (i) stand-alone, (ii) in- band, and (iii) guard-band. Fig. 1 depicts all the possible NB- IoT deployments in frequency spectrum.

    To be able to enable a long-term battery powered use- cases, 3GPP Releases 12 and 13 introduced such features as extended Discontinuous Reception (eDRX) and Power-Saving Mode (PSM) to support this type of operation aiming to optimize the power consumption. In most use cases, the device actually spends the majority of its lifetime in idle or power

    1See “Vodafone Brings NB-IoT to UK, Starts Trial With Scottish Power” by Light Reading, 2018: https://www.lightreading.com/iot/nb-iot/vodafone- brings-nb-iot-to-uk-starts-trial-with-scottish-power/d/d-id/746377

  • saving mode as most of the IoT applications only require infre- quent transmission of relatively short packets. Traditionally, an idle device function is to monitor paging and perform mobility measurements, although, the energy consumption during idle mode is much lower in comparison with the connected mode. Further energy saving can be achieved by simply increasing the periodicity between paging occasions or not requiring the device to monitor paging at all in case of PSM.

    NB-IoT 200 kHz (1 x 180 kHz PRB)

    Without guardband

    With guardband

    NB-IoT in LTE

    guardband

    NB-IoT inside LTE band

    NB-IoT 200 kHz in GSM band LTE bandwidth 5 MHz

    Fig. 1. The possible NB-IoT deployments: NB-IoT stand-alone deployment using refarmed GSM / LTE spectrum; inside an LTE carrier, either using one of the LTE PRBs (in-band deployment) or using the LTE guard-band (guard- band deployment).

    In essence, a device can switch off its radio module and only keep a basic oscillator running for the sake of keeping a time reference to know when it should come out of the PSM or eDRX. The reachability during PSM is set by the Tracking Area Update (TAU) timer with the maximum settable value exceeding one year. Moreover, eDRX can be configured with a DRX cycle just below 3 hours [12], [13]. The overall summary diagram of end-device behavior in NB-IoT network is depicted in Fig. 2.

    0 10 20 30 40 50 60 Time [s]

    0.05

    0.10

    0.15

    0.20

    0.25

    0.30

    C ur

    re nt

    [A ]

    PS M

    TA U

    D R

    X

    D R

    X

    PS M

    ID LE

    M es

    sa ge

    T X

    R R

    C R

    el ea

    se

    A tt

    ac h

    R eb

    oo t

    Fig. 2. Summary diagram of end-device behavior in NB-IoT with the utilization of release assistance to further decrease the power consumption.

    B. Our Contribution

    In this work, we report our unique cooperation with Voda- fone Czech Republic a.s. telecommunications operator, with the goal to design the NB-IoT prototype for delay-tolerant services in Czech Republic. First, we discuss our design of the NB-IoT board focused on the ability to measure and evaluate the transmission parameters while sending data from end-device towards