Editor's Note: Growing requirements for increased availability of IoT devices coincide with the emergence of cellular technologies well suited for the IoT . For developers, the need has never been more acute for more detailed information about cellular technologies and their application to the IoT.
Excerpted from the book, Cellular Internet of Things, this series introduces key concepts and technologies in this arena. In this installment, the authors describe the evolving landscape for cellular and its role in the IoT.
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Adapted from Cellular Internet of Things, by Olof Liberg, Marten Sundberg, Eric Wang, Johan Bergman, Joachim Sachs.
Chapter 1. Cellular Internet of Things
By Olof Liberg, Marten Sundberg, Eric Wang, Johan Bergman, Joachim Sachs
This chapter introduces the overall content of the book. It contains a brief introduction to the massive Machine-Type Communications (mMTC) category of use cases, spanning a wide range of applications such as smart metering and wearables. When discussing these applications, special attention is given to the service requirements associated with mMTC, for example, in terms of reachability, throughput, and latency. The chapter continues and introduces the concept of the Cellular Internet of Things (CIoT) and the three technologies Extended Coverage Global System for Mobile Communications Internet of Things (EC-GSM-IoT), Narrowband Internet of Things (NB-IoT), and Long-Term Evolution for Machine-Type Communications (LTE-M) that can be said to define this concept. While EC-GSM-IoT and LTE-M are backward compatible solutions based on GSM and LTE, respectively, NB-IoT is a brand new radio access technology.
The final part of the chapter looks beyond the set of cellular access technologies and introduces the Low Power Wide Area Network (LPWAN) range of solutions that already have secured a significant footprint in the mMTC market. Unlike the cellular systems, these LPWANs have been designed to operate in licensed exempt spectrum. An initial discussion around the pros and cons of licensed exempt operation is presented to prepare the reader for the final chapters of the book, where a closer look is taken at operation in the unlicensed frequency domain.
The Internet of Things, commonly referred to as IoT, is the latest rising star in the information and communications technology (ICT) industry and embodies the vision of connecting virtually anything with everything. Cisco estimates that 12 billion devices will be connected by 2020 . Ericsson goes even further in its vision of 18 billion connected devices in 2022 . Regardless of which of these two leading ICT network providers has made the best estimate, the anticipated number of devices is nothing short of dazzling. As a comparison, the total number of mobile cellular subscriptions currently amounts to 7.3 billion .
So what is it that will become connected, that is not already connected? Traditional use cases such as connecting utility meters to support, e.g., distribution and billing, will likely increase in numbers. A recent example is the Great Britain Smart Metering Implementation Programme, where the British government has decided to replace 53 million meters in roughly 30 million premises with advanced electricity and gas meters intended to support customers with “near real- time information on their energy consumption” . Similar projects are either in progress or in the planning stages in a majority of the European Union member states . At the same time, new use cases, for example, in the category of Wearables, are gaining momentum with increasing market traction being realized.
When viewed in totality, the overall number of connected devices is already undergoing an exponential growth where connectivity over cellular networks serves as a key enabler for this growth. Between 2015 and 2021, it has been approximated that the volume of devices connected to the Internet via cellular technologies alone will experience a compounded annual growth rate of roughly 25% .
This accelerated growth in cellular devices is supported, or perhaps driven, by the recent work performed by the Third Generation Partnership Project (3GPP) standards development organization in Release 13 of its featured technologies. 3GPP has already been responsible for standardization of the GSM (2G), UMTS (3G), and LTE (4G) radio access technologies. The early development and evolution of these technologies has mainly been driven by traditional service requirements defined by voice and mobile broadband services. In the past couple of years, new requirements for machine connectivity have emerged in support of the IoT and transformed the process of standards evolution into what can be seen as a fast-moving revolution. Accordingly, the designs of GSM and LTE have been rethought, and a new radio access technology dedicated to supporting the IoT has been developed, resulting in three new CIoT technologies becoming globally available within a very short time frame. The mission of this book is to introduce, characterize, and, when relevant, in detail describe these three new technologies known as EC-GSM-IoT, NB-IoT, and LTE-M.
EC-GSM-IoT is a fully backward compatible solution that can be installed onto existing GSM deployments, which by far represent the world’s largest and most widespread cellular technology. EC-GSM-IoT has been designed to provide connectivity to IoT type of devices under the most challenging radio coverage conditions in frequency deployments as tight as 600 kHz.
NB-IoT is a brand new radio access technology that in some aspects reuses technical components from LTE to facilitate operation within an LTE carrier. The technology also supports stand-alone operation. As the name reveals, the entire system is operable in a narrow spectrum, starting from only 200 kHz, providing unprecedented deployment flexibility because of the minimal spectrum requirements. The 200 kHz is divided into channels as narrow as 3.75 kHz to support a combination of extreme coverage and high uplink capacity, considering the narrow spectrum deployment.
LTE-M is based on LTE, which is by far the fastest growing cellular technology. LTE-M provides just as EC-GSM-IoT and NB-IoT ubiquitous coverage and highly power efficient operation. Using a flexible system bandwidth of 1.4 MHz or more, the technology is capable of serving higher-end applications with more stringent requirements on throughput and latency than what can be supported by EC-GSM-IoT and NB-IoT.
The fact that they can provide reliable communication under extreme coverage conditions while supporting battery life of many years and also realizing securely encrypted communication is said to be common to all of these technologies. All three technologies have also been designed to enable ultra- low device complexity and cost, which are important factors considering the objective of providing connectivity to billions of devices supporting diverse services and applications.
3GPP is, however, not the only organization supporting the accelerated growth in a number of connected devices. This book therefore goes beyond EC-GSM-IoT, NB-IoT, and LTE-M to provide an overview of the competitive IoT landscape and introduces a few of the most promising technologies operating in unlicensed spectrum. Both short-range solutions and long-range solutions established in the so-called LPWAN market segment are presented. As these technologies are targeting unlicensed frequency bands, they are following different design principles compared to the 3GPP technologies, which are developed for licensed frequency bands. To be able to distinguish between technologies for licensed and unlicensed operation, the book sets out to introduce and analyze the regulations associated with device operation in the most recognized license exempt frequency bands.
The book will finally provide a glimpse of the future and describe how the CIoT technologies are expected to evolve to support new use case and meet the latest market requirements. Also, the work on a fifth generation (5G) communication technology ongoing within the International Telecom Union (ITU) and 3GPP will be presented. In this context 5G features such as mMTC and Ultra Reliable and Low Latency Communication (URLLC) will be introduced.
1.2 NEW APPLICATIONS AND REQUIREMENTS
1.2.1 LEADING UP TO THE CELLULAR INTERNET OF THINGS
The CIoT may be the latest hype in the mobile industry, but cellular communication for mobile telephony has actually been well established for more than three decades. Over time, it has evolved from being a niche product in developed countries to become an everyday commodity reaching almost every corner of the world. It has, since its introduction in the early 1980s, had a considerable impact on many aspects of the way we live our lives. A significant milestone in the short but intense history of mobile telephony was the introduction of the smartphone. With it came a framework for developing and distributing smart and compact applications that pushed mobile phone usage far beyond the traditional use cases of making voice calls and sending text messages. Today a smartphone is as advanced as any computer and allows the user to manage everything from personal banking services to social interaction with friends and family while listening to the latest music from the hit charts. The obvious advantage of the smartphone over other connected devices is its convenient form factor and its seamless wireless connectivity that allows the user to access the Internet whenever and wherever.
The introduction of the smartphone not only changed the usage of the phone but also had a profound impact on the requirements on the underlying communication systems providing the wireless connectivity. For a classic mobile phone supporting voice and text messages, the most important requirements are acceptable voice quality and reliable delivery of messages. Since the introduction of the smartphone, expectations go far beyond this and requirements in terms of, e.g., high data rates and low latency have become more prominent. The requirements set by the ITU on the world’s first 4G systems were also to a significant extent shaped by this and focused on the ability of the candidate solutions to provide mobile broadband services. For base station to device transmission, a peak downlink data rate of 1.5 Gbit/100 MHz/s was one of the ITU targets. For the uplink direction, i.e., transmission from the device to the base station, the target was slightly relaxed to 675 Mbit/100 MHz/s. A latency of less than 10 ms was another important requirement intended to secure an acceptable mobile broadband experience .
With the introduction of Machine-to-Machine (M2M), MTC, and IoT applications and services, the expectations as well as the set of requirements placed on the mobile communication technologies changed again. A not too advanced smartphone user may, for example, stream several gigabits of data every month with high requirements on quality of experience while it may be sufficient for an average utility meter to access the network once per day to send the latest billing information of a few bytes to a centralized billing system. The requirements associated with M2M and IoT services are not, however, only being relaxed, they are becoming more diverse also, as new applications are emerging. Although the mentioned utility meter displays relaxed requirements in terms of latency and throughput, other requirements may be far more stringent than what is expected from the smartphone use case. It is not rare for utility meters located deep indoors, for example, in basements, to place high requirements on the wireless coverage provided by the supporting communications systems. It is furthermore expected that the number of M2M and IoT devices will, by far, eventually outnumber the smartphone population and thereby effectively set new requirements on system capacity and network availability.
The next installment describes massive machine-type communications (mMTC) and ultra reliable low latency communications (URLLC).
Reprinted with permission from Elsevier/Academic Press, Copyright © 2017