Cellular IoT — Which technology to select

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 an earlier series, the authors described the evolving landscape for cellular, its role in the IoT, and technologies for massive machine-type communications (mMTC) and ultra reliable low latency communications (URLLC).

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Adapted from Cellular Internet of Things, by Olof Liberg, Marten Sundberg, Eric Wang, Johan Bergman, Joachim Sachs.

Chapter 9. The competitive Internet of Things technology landscape (Cont.)

By Olof Liberg, Marten Sundberg, Eric Wang, Johan Bergman, Joachim Sachs

9.3 CHOICE OF CIoT TECHNOLOGY (Cont.)

9.3.2 WHICH CIoT TECHNOLOGY TO SELECT

The choice of a CIoT solution is a decision that needs to be taken by different market players. On one hand, it is the mobile network operator that has to decide which CIoT technology to add to its existing network. On the other hand, it is the IoT device manufacturer and service provider, which select for which IoT connectivity options they develop their IoT service. It can be expected that different options of solutions will coexist.

9.3.2.1 The Mobile Network Operator’s Perspective

For a mobile network operator, the decision about which CIoT technology to deploy and operate has multiple facets. There are in particular two sides that need to be considered:

  • Long-term mobile network strategy and existing assets,

  • IoT market segment strategy. 

A typical mobile network operator has one or more cellular networks deployed. Increasingly, different radio technologies are provided via a single multiradio technology network. For example, the same base station can be used for GSM, UMTS/HSPA, or LTE transmission. But there are also deployments where the networks for 2G, 3G, and 4G are rather independent in their deployment and operation. 

In addition, a mobile network operator has a spectrum license from typically a national regulator, which gives rights to operate a network in the assigned spectrum. Spectrum licenses are typical long-lasting, like e.g., 20 years; this is motivated by providing network operators with an economic safety. A return on investment for an extremely high network installation cost of a new technology can be planned over a long period. On expiry of a spectrum license, a spectrum licensing contest, like a spectrum auction, is initiated by the regulator for providing a new spectrum license. In general, any network build-out roadmap by an operator is a long-term decision and needs to consider at least the following elements:

  • How long are the existing spectrum licenses valid, what technologies are allowed to be operated in the spectrum, and when is a new spectrum reallocation process planned by the regulator?

  • What is the status of the network build-out for different radio technologies, in particular GSM and  LTE, and what is the operator’s market share?

  • What is the network build-out of competing operators and what is their market share?

  • What is the strategic intent of an operator concerning IoT?

  • What services are planned to be provided, and on what roles does the operator intend to address the IoT market (e.g., as connectivity provider or also as service provider/enabler)?

  • What is the market maturity for IoT services?

  • What IoT segment would the operator like to address? 

It shall be noted that the above questions are raised from a perspective of the operation of an operator network in a specific country. However, several operators are active in multiple countries and even on multiple continents. Even if the decision is largely made per country, an operator may want to harmonize decisions over multiple regions in which it operates networks. 

When looking at the CIoT technology options, the following characteristics can be identified, which will influence an operator’s decision. 

As a baseline, we assume that there is a very large incentive by an operator to reuse existing mobile network infrastructure for deploying any of the CIoT technologies. Naturally, EC-GSM-IoT can be easily deployed based on a GSM infrastructure and by using GSM spectrum. The GSM network resources and the GSM spectrum would be shared between GSM usage and EC-GSM-IoT usage. LTE-M and NB-IoT can be deployed based on an LTE infrastructure and by using the LTE spectrum; LTE network and spectrum resources would be shared between LTE, LTE-M, and NB-IoT usage. In most network configurations, it can be expected that the deployment of EC-GSM-IoT, LTE-M, and NB-IoT can be realized as a software update to the deployed GSM or LTE networks. This implies that the introduction of the CIoT into the market can be realized by operators rather quickly and at a low total cost of ownership. 

For IoT services it is expected that many services expect a long service lifetime of, e.g., a decade. This expectation should be addressed with a CIoT network. As a result, the decision of the CIoT technology is also coupled to the operator’s long-term strategy for mobile networks focusing on telephony and mobile broadband services. If an operator intends to transition GSM deployments to, e.g., LTE or 5G in the coming future, an introduction of EC-GSM-IoT seems a questionable choice, as any long-term EC-GSM- IoT users would require to maintain the GSM infrastructure operational for a long time. 

GSM is today still the cellular network technology, which covers the largest part of the globe. According to Reference [55] in 2016 around 90% of the world population was within coverage of a GSM network, and this is expected to increase to w95% by 2022. In contrast, in 2016 only around 40% of the population were within the coverage of an LTE network, which is expected to increase to more than 80% by 2022. However, there are very large regional variations in the spread of cellular technologies. To give some example from Reference [55], in the Middle East and in Africa only 5% of mobile subscriptions in 2016 were LTE subscriptions (which also enable to use WCDMA/HSPA and GSM); this number is expected to increase to around 30% by 2022. Approximately 20% of the subscriptions are GSM-only and a majority of subscriptions is for WCDMA/HSPA (which also enables to use GSM but not LTE). In regions like Middle East and Africa, GSM is predicted to continue being an important technology for many years to come, even if in other regions the mid- and long-term role of GSM is less certain. Looking at North America, already in 2016 65% of mobile subscriptions were LTE subscriptions. For 2022 very few non-LTE-capable [see Note 1] subscriptions are foreseen. Such differences will result in different preferences of CIoT solutions for different operators in different regions. [Note 1: As LTE-capable subscription in 2022 we count here the predicted LTE subscriptions as well as 5G subscriptions, which are assumed to be fully compatible for operation in LTE networks.]

While the reuse of existing network infrastructure and spectrum is an important aspect for an operator, a specific benefit of NB-IoT shall be pointed out in its spectrum flexibility. It is generally expected that existing GSM/LTE spectrum deployments are extended to also include EC-GSM-IoT/ LTE-M traffic, so the IoT traffic will be on the same spectrum that is already deployed for telephony and mobile broadband services. For NB-IoT, the narrow system bandwidth of NB-IoT makes it suitable to be deployed also in spectrum that is not used for mobile broadband services today. Examples exist, where operators have spectrum allocations that do not fit with exact carrier bandwidths provided by LTE. As a result, a remainder of the spectrum allocation remains unused. NB-IoT provides the flexibility to make use of even small portions of idle spectrum resources that an operator may have. Such portions of spectrum resources can be even created by an operator, e.g., by emptying individual GSM carriers from GSM operation and reuse them instead for NB-IoT usage.

A further aspect of spectrum being available to an operator can influence the choice of CIoT technology. EC-GSM-IoT and NB-IoT have been specified for use in FDD bands. LTE-M, in contrast, can be used for both TDD and FDD bands and provides more opportunities to operators with significant TDD spectrum allocations.

Finally, an operator may align a CIoT plan with its future deployment plans of a 5G New Radio (NR) technology. Many early 5G NR deployments are planned for higher frequency bands; but some operators may also consider an NR deployment in low frequency bands that may be used for CIoT. In the ongoing 5G standardization activities within 3GPP, it has already been identified, that a backward compatible operation of NR with NB-IoT and LTE-M should be envisioned. For example, NB-IoT should be able to be operated in-band within an NR carrier in a similar way as if it is deployed in-band within an LTE carrier. With the same approach, LTE-M operation could be enabled in-band within an NR carrier. Two scenarios should be supported. In the first, NB-IoT is deployed on some carrier (e.g., some reassigned GSM carriers), and the entire GSM band is then at a later time refarmed to NR. The NB-IoT operation for existing IoT services should be able to continue within the NR carrier after the refarming. Similarly, in the second scenario, an LTE carrier should be possible to be refarmed to NR, while continuing the operation of LTE-M services on that carrier. Similar close coexistence of EC-GSM-IoT and NR on a common carrier will not be possible.

The considerations presented so far for choosing a CIoT technology by a mobile network operator have been based on what spectrum and what radio access technology the operator use or plan to use in future. The driving force in this regard is to reuse existing or planned mobile networks to achieve a low capital expenditure and operational expenditure for the deployment and operation of CIoT connectivity. Another major component in an operator assessment of CIoT is the IoT service strategy of the operator. Does the operator target a specific IoT market segment? And if so, what are the service requirements in this segment and what connectivity requirements does it imply? In this case the operator decision is largely based on how well a CIoT technology fulfills the service requirements, as discussed in Section 9.3.1.

9.3.2.2 The IoT Service Provider’s Perspective

An IoT service provider targets with its offering a set of particular IoT services. For example, a focus may be on smart city applications or precision agriculture. The targeted IoT service implies a certain location where the service will be realized, i.e., where IoT devices will be located. For smart city services, this will be in urban areas, for precision agriculture this will be primarily in rural areas. The IoT service characteristics determine what kind of traffic profile needs to be supported for realizing the service. For smart city this may be regular monitoring of available parking spaces or notifications when waste containers have reached a certain fill level. For precision agriculture, it can be the monitoring of humidity and fertilization on fields or in green houses or the tracking of cattle. Other IoT service characteristics besides the traffic profile can be the maximum time that a device must operate on a battery.

Based on an analysis of the targeted IoT service, the connectivity requirement of the service becomes clear:

  • What data rates need to be supported by the communication?

  • Do devices need to run on battery for extended time periods?

  • What device density is expected?

  • Where are the devices located?

  • Are devices in particularly hard to reach locations (e.g., in enclosures underground)?

  • Are devices mobile over larger areas, possibly even across national borders? 

Based on this review a service provider can determine:

  • Which CIoT technologies provide sufficient performance for the targeted service, see Section 9.3.1.

  • At what locations network coverage is needed. 

  • It can be expected that coverage of multiple CIoT technologies is provided by one or more network operators at various locations. EC-GSM-IoT will be provided as technology in markets where the LTE network build-out is not so advanced. In other markets with significant LTE deployments, both LTE-M and NB-IoT will be found. An IoT service provider has to select a network operator that provides coverage and connectivity via a suitable CIoT technology at the targeted deployment area at a fair price. 

  • Since IoT devices may be deployed and operated over long time spans, flexibility in reselecting a network provider is desirable. Embedded Subscriber Identity Modules (SIM) that enable to remotely reprovision devices and reselect network providers will play an increasing role for CIoT devices, see Reference [56]. 

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The installment concludes this excerpt.

Reprinted with permission from Elsevier/Academic Press, Copyright © 2017

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