Chapter 1
The Internet of Things
Abstract
This chapter introduces the overall content of the book. It contains an introduction to the massive and critical machine-type communications (mMTC, cMTC) categories of use cases, spanning a wide range of applications. When discussing these applications, consideration is given to the service requirements associated with mMTC and cMTC for example in terms of reachability and reliability. The chapter introduces the concept of the cellular Internet of Things which is defined by the Third Generation Partnership Project (3GPP) technologies: Extended Coverage Global System for Mobile Communications Internet of Things (EC-GSM-IoT), Narrowband Internet of Things (NB-IoT), Long-Term Evolution for Machine-Type Communications (LTE-M) and ultra-reliable and low latency communications (URLLC). The final part of the chapter looks beyond the 3GPP technologies and discusses a range of solutions that provides IoT connectivity in unlicensed spectrum.
1.1. Introduction
The Internet of Things (IoT) is part of a transformation that is affecting our entire society: industries, consumers and the public sector. It is an enabler in the broader digital transformation of the management of physical processes. It provides better insights and allow for
more efficient operation. The IoT provides the capability to embed electronic devices into physical world objects and create smart objects that allow us to interact with the physical world by means of sensing or actuation. IoT enables networking among smart objects, applications and servers.
Fig. 1.1 depicts the instance of an IoT system. On the left-hand side there are physical assets – like machines, lights, meters; on the right-hand side there are applications interacting with the physical world. There can be a variety of different applications. If we assume as example, that the physical assets are sensors that monitor the vehicle flow on a street at different locations in a city, then the application could be to monitor traffic flows throughout the city in a traffic control center. In case that the physical assets include traffic lights, which can be activated via actuators, then the application could also steer the red-green periods of individual traffic lights, e.g. based on the observed traffic flow. This shows a simple example of digital transformation. A traffic infrastructure with traffic lights with fixed configuration is transformed into a smarter traffic infrastructure, where insights about the system states are collected and smart decisions are being taken and executed within the infrastructure. The applications themselves are running in the digital domain. A representation of the physical system (i.e. streets in the city) is created, based on a model (like a street map), and it is updated with information from the traffic sensors. The management and configuration of the traffic infrastructure (i.e. the traffic lights) is made in the traffic center and the execution is transferred back to the physical world, by means of switches in the traffic lights that steer the red-green phases.
The IoT system is the enabler for the service in the above example. IoT devices are connected to the physical assets and interact with the physical world via sensors and actuators. The IoT system connects the IoT devices to the specific application of the service and
enables the application to control the physical assets via actuators connected to IoT devices. The IoT platform provides common functionality, which includes device and object identification and addressing, security functions, and management of IoT devices. The IoT connectivity, which is the focus of this book, provides a generic platform that can be used by many different services, as shown in Fig. 1.2.
1.2. IoT communication technologies
A significant number of communication technologies have been developed over the last two decades with significant impact on the IoT. In particular, machine-to-machine (M2M) communication solutions were developed to connect devices with applications. Most M2M communication solutions are purpose-build and designed to satisfy a very particular application and communication needs. Examples are connectivity for remote-controlled lighting, baby monitors, electric appliances, etc. For many of those systems the entire communication stack has been designed for a single purpose. Even if it enables, in a wider sense, an environment with a wide range of connected devices and objects, it is based on M2M technology silos, usually without end-to-end IP connectivity and instead via proprietary networking protocols. This is depicted on the left-hand side of Fig. 1.3. It is quite
different from the vision of the IoT depicted on the right-hand side in Fig. 1.3, which is based on a common and interoperable IP-based connectivity framework for connecting devices and smart objects, which enables the IoT at full scale.
1.2.1. Cellular IoT
In recent years the Third Generation Partnership Project (3GPP) have evolved their cellular technologies to target a wide variety of IoT use cases. The second, third and fourth generations cellular communication systems provided since earlier connectivity for the IoT, but 3GPP is since its Release 13 developing technologies that by design provide cellular IoT connectivity. The 3GPP standardization of cellular networks is trying to address the requirements of novel IoT use case, in order to ensure that the technology standards evolution is addressing future market needs. It has become clear that the breadth of IoT use cases cannot be described with a simple set of cellular IoT requirements. In the standardization of the fifth generations (5G) cellular system, three requirements categories were defined to be addressed (see Fig. 1.4) [1]. Two of them are focused on machine-type communication (MTC), essentially addressing the IoT.
Massive MTC (mMTC) is defined for addressing communication of large volumes of simple devices with a need of small and infrequent data transfers. It is assumed that mMTC devices can be massively deployed, so that the scalability to many connected devices is needed, as well as the support to reach them with the network wherever they are located. The ubiquity of the deployment in combination with a need to limit deployment and operation cost motivates ultra-low complex IoT devices that may need to support non-rechargeable battery powered operation for years. Examples of mMTC use cases are utilities metering and monitoring, fleet management, telematics and sensor sharing in the automotive industry segment, or inventory management, asset tracking and logistics
in the manufacturing segment. 3GPP has specified the Extended Coverage Global System for Mobile Communications Internet of Things (EC-GSM-IoT), Narrowband Internet of Things (NB-IoT) and Long-Term Evolution (LTE) for Machine-Type Communications (LTE-M) technologies for support of mMTC. These solutions are thoroughly examined in Chapters 3–8.
Critical MTC (cMTC) is defined for addressing demanding IoT use cases with very high reliability and availability, in addition to very low latencies. Examples of cMTC use cases exist in various fields. In the automotive area, remote driving falls into this category, but also real-time sensor sharing, autonomous driving, cooperative maneuvers and cooperative safety. Other examples are teleprotection and distribution automation in a smart grid, automated guided vehicles in manufacturing or remote control of vehicles and equipment in smart mining. The cMTC requirement category is in the 3GPP standardization also referred to as ultra-reliable and low latency communication (URLLC). In this book we use the term URLLC for the technologies supporting the cMTC use cases. Chapters 9–12 provides the design details and performance of LTE URLLC and NR URLLC. The performance evaluations compare the achieved performance to the set of 5G performance requirements agreed for cMTC in terms of reliability and latency. It is shown that both LTE URLLC and NR URLLC meets all the minimum requirements, while the NR technology is shown to excels in terms of spectral efficiency, minimum achieved latency and deployment flexibility.
Even the categorization of mMTC and cMTC is rather coarse and does not address all IoT use cases. To better define the requirements that a certain use case puts on the devices and the supporting network, the information and communications technology (ICT) industry
leader Ericsson has introduced a novel classification of Cellular IoT in the segments massive IoT, broadband IoT, critical IoT and industrial automation IoT as described in [2] and shown in Fig. 1.5.
Massive IoT and critical IoT are equivalent to mMTC and cMTC, respectively. Broadband IoT covers cellular IoT features, that are not explicitly addressed so far in standardization as a category. It applies to use cases with similar objectives as for massive IoT, in terms of battery efficient operation, device complexity and wide-area availability, but where in addition very high data rates are needed. To this end a certain comprise in terms of battery usage and device complexity is required to cater for high throughput. Examples are the transmission of high-definition maps for (semi-)autonomous vehicles, large software updates, computer vision systems, augmented or mixed reality systems, advanced wearables or aerial and ground vehicles. Drone communication is an example of an important broadband IoT use case that in recent years have grown quickly in importance and have a potential to bring significant social-economic benefits. Drones are increasingly used for aiding search, rescue, and recovery missions during or in the aftermath of natural disasters. Chapter 13 introduces the work 3GPP has done for the support for drone communication in LTE.
Industrial automation IoT covers cellular IoT features, that provide capabilities required for some industrial segments, in particular in the area of industrial automation. These are typically additional functional capabilities, rather than novel performance requirements. Often those features are needed in clearly localized solutions, like a cellular IoT system provided within a factory. An example for industrial automation IoT is the support for non-public network solutions, for native Ethernet transport with advanced LAN services and optimizations for time sensitive networking. Other examples are the support for precise time-synchronization that is provided from a time master clock over the cellular system to end-devices, or ultra-precise positioning. Chapter 16 is providing
further insights into industrial automation IoT when discussing the concept of industrial internet of things.
1.2.2. Technologies for unlicensed spectrum
The 3GPP cellular technologies are not the only solutions competing for IoT traffic. Well-known technologies such as Bluetooth and Wi-Fi also serve as bearers for MTC traffic. A distinction between the group of cellular technologies and Bluetooth and Wi-Fi is that the former is traditionally intended for operation in licensed spectrum while the latter two belong to the group of systems operating in unlicensed spectrum, in so-called license exempt frequency bands.
Licensed spectrum corresponds to a part of the public frequency space that has been licensed by national or regional authorities to a private company, typically a mobile network operator, under the condition of providing a certain service to the public such as cellular connectivity. At its best, a licensed frequency band is globally available, which is of considerable importance for technologies aiming for worldwide presence. The huge success of GSM is, for example, to a significant extent built around the availability of the GSM 900
MHz band in large parts of the world. Licensed spectrum is, however, commonly associated with high costs, and the media frequently give reports of spectrum auctions bringing in significant incomes to national authorities across the world.
Unlicensed spectrum, on the other hand, corresponds to portions of the frequency space that can be said to remain public and therefore free of licensing costs. Equipment manufacturers using this public spectrum must meet a set of national or regional technical regulations for technologies deployed within that spectrum. Among of the most popular license exempt frequency bands are the so-called Industrial, Scientific and Medical (ISM) bands identified in article 5.150 of the ITU Radio Regulations [3]. Regional variations for some of these bands exist, for example, in the frequency range around 900
MHz while other bands such as the 2.4
GHz band can be said to be globally available. In general, the regulations associated with license exempt bands aim at limiting harmful interference to other technologies operating within as well as outside of the unlicensed band.
Bluetooth and Wi-Fi, and thereto related technologies such as Bluetooth Low Energy, ZigBee, and Wi-Fi Halow, commonly use the ISM bands to provide relatively short-range communication, at least in relation to the cellular technologies. Bluetooth can be said to be part of a wireless personal area network while Wi-Fi provides connectivity in a wireless local area network (WLAN). In recent years, a new set of technologies have emerged in the category of low power wide area networks (LPWAN). These are designed to meet the regulatory requirements associated with the ISM bands, but in contrast to WPAN and WLAN technologies they provide long-range connectivity, which is an enabler for supporting wireless devices in locations where WPAN and WLAN systems cannot provide sufficient coverage.
Chapter 14 reviews the most important license exempt spectrum regulations and introduces some of the most popular and promising IoT technologies for unlicensed spectrum operation. Chapter 15 describes the 3GPP based IoT systems specified by the MulteFire Alliance (MFA). The MFA is a standardization organization that develops wireless technologies for operation in unlicensed and shared spectrum. The MFA specifications are using the
3GPP technologies as baseline and add adaptations needed for operation in unlicensed spectrum.
1.3. Outline of the book
The content of the book is distributed over 18 chapters. Chapter 2 introduces the 3GPP and the MFA standardization forums. It presents an overview of the early work performed by 3GPP to support IoT on 2G, 3G and 4G. The last part of the chapter provides an introduction to 3GPPs most recent work on 5G.
Chapters 3 to 8 focuses fully on the work 3GPP so successfully have carried out on technologies supporting mMTC. Chapters 3, 5 and 7 presents descriptions of the physical layer design and the higher and lower layer procedures for each of EC-GSM-IoT, LTE-M and NB-IoT. Chapters 4, 6 and 8 in detail evaluate the performance of each of the three technologies. For LTE-M and NB-IoT the performance evaluations show that the systems in all aspects meets the 5G performance requirements for mMTC services defined by 3GPP and the International Telecommunications Union Radiocommunication sector (ITU-R).
Chapters 9–12 provides the design details and performance of LTE and NR URLLC. The performance evaluations compare the achieved performance to the set of 5G performance requirements agreed for cMTC in terms of reliability and latency. It is shown that both LTE and NR support the 5G requirements from ITU-R on cMTC in terms of reliability and latency. NR is shown to be more flexible in its design than LTE and offers a higher performance.
Chapter 13 discusses the enhancements 3GPP Release 15 introduced on LTE for the support of drone communication. It is described how LTE efficiently can support the reliable command-and-control communications required for drone operation.
Chapter 14 and 15 turns the attention from licensed spectrum operation associated with 3GPP and gives full attention to operation in unlicensed frequency bands. Chapter 14 describes the most popular short- and long-range wireless technologies for providing IoT connectivity in unlicensed spectrum. Chapter 15 presents the work of the MFA on adapting LTE-M and NB-IoT for operation in unlicensed spectrum bands. In this book we refer to these technologies as LTE-M-U and NB-IoT-U, where the ‘U’ stands for unlicensed.
Chapter 16 summarizes the descriptions and performance evaluations provided in the earlier chapters and gives the reader an insight in how to best select an IoT system for meeting mMTC and cMTC demands. This guidance is based on the technical capabilities and performance of each of the systems presented in the book.
Chapter 17 provides the reader with an overall picture of the IoT. It is shown that the wireless connectivity is only one among many vital technical components in an IoT system. IoT transfer protocols and the IoT application framework are discussed in this chapter.
Chapter 18 wraps up the book with a look into the future and discusses where the cellular industry is turning its attention when continuing evolving 5G (Fig. 1.6).
