The iot technology landscape embedded static electricity examples


This chapter provides an overview over connectivity solutions for Internet of Things (IoT) devices. An overview of short-range radio and low power wide area technologies that operate in unlicensed spectrum is given. Also the characteristics of using unlicensed spectrum are described. The properties of unlicensed technologies are compared with the CIoT technologies that operate in licensed spectrum. Finally, the performance of the different CIoT technologies, Extended Coverage Global System for Mobile Communications Internet of Things (EC-GSM-IoT), Long-Term Evolution for Machine-Type Communications (LTE-M), and Narrowband Internet of Things (NB-IoT) is reviewed and compared with each other. Benefits of the different CIoT technologies are discussed.

CIoT networks, such as EC-GSM-IoT, LTE-M, and NB-IoT operate in licensed spectrum. This means that mobile network operators have acquired long-term spectrum licenses from regulatory bodies in the country/region after, for example, an auction process. Such licenses provide an operator with exclusive spectrum usage right for a carrier frequency. Such spectrum licenses may also be combined with an obligation to build out a network and provide network coverage and communication services in a certain area within a certain time frame. This obligation in combination with the cost of the license motivates mobile network operators to invest upfront into a network infrastructure. This exclusive spectrum usage right provides the prospect of good financial returns on the investment obtained via communication services within the lifetime of the license. There are also other spectrum bands, which do not abide to the rules of licensed spectrum. In unlicensed or license-exempt spectrum any device is entitled to transmit as long as it fulfills the regulation without requiring any player from holding a license. These regulatory requirements have the objective to harmonize and ensure efficient use of the spectrum.

Unlicensed spectrum bands differ for different regions in the world. In the following an overview of the usage of unlicensed spectrum is provided for two bands, one at around 900 MHz and one at 2.4 GHz. These are of particular relevance due to their ability to cater for IoT services and popular wireless communication standards such as Wi-Fi and Bluetooth have been specified for these bands. The sub-GHz range around 900 MHz provides attractive propagation characteristics in terms of facilitating good coverage. The 2.4 GHz range is interesting because it is considered to be a global band, which is important for systems targeting a global footprint. While the 2.4 GHz band is globally harmonized, the sub-GHz range has regional variations. However, most regions have some unlicensed spectrum allocation even if they differ in their specifics. A more detailed description is here provided for the US unlicensed spectrum at 902-928 MHz and the European unlicensed spectrum at 863-870 MHz. In Europe, some differences in the allocations of the 863-870 MHz band exist on a per country basis. There has been significant market traction for IoT connectivity solutions operating in the unlicensed frequency domain in these two regions. In other regions, the unlicensed spectrum allocation in the sub-GHz range varies for different countries. For example, the allocations in Korea and Japan are overlapping with the US spectrum region, and China has an allocation that is below the European spectrum allocation, see e.g., Reference [1]. Radio technology standards that are addressing the unlicensed spectrum around 900 MHz, such as, IEEE 802.11ah, are typically designed in a way, in which they provide a common technology basis for different channelization options in this spectrum range; the detailed channelization is then adopted to the region where it is deployed, see e.g., Reference [1] for the channelization of IEEE 802.11ah. IEEE 802.11ah is the basis upon which Wi-Fi HaLow is built.

For the United States, the usage of unlicensed spectrum for communication devices is regulated by the Federal Communications Commission (FCC) and it is specified in Title 47 Code of Federal Regulations Part 15 [2]. For Europe, the spectrum rules are specified by the European Conference of Postal and Telecommunications Administrations (CEPT), which is a coordination body of the telecommunication and postal organizations within Europe. As of today, 48 countries are members of CEPT [3]. The CEPT recommendation for usage of short-range devices in unlicensed spectrum is described in Reference [4]. This recommendation is the basis for European Telecom Standards Institute (ETSI) harmonized standards, which specify technical characteristics and measurement methods for devices that can be used by device implementers to validate their devices for conforming with the regulated rules. Such ETSI standards are as follows:

Some of the more relevant spectrum usage rules for unlicensed spectrum at 863-870 MHz in Europe is given in Table 9.1 and for 902-928 MHz in the United States in Table 9.2. The tables present, e.g., the maximum allowed radiated power and requirements for interference mitigation. While the ETSI regulations in the band 863-870 MHz mandate the power in terms of Effective Radiated Power (ERP), i.e., the radiated power assuming a half-wave dipole antenna, the FCC setsrequirements in terms of conducted power in combination with allowed antenna gain. Here we have converted these requirements to Equivalently Isotropically Radiated Power (EIRP), i.e., the radiated power assuming an isotropic antenna, according to the following equation: