4G and the opportunity behind 2G and 3G network sunsets

While the forced upgrade will disrupt businesses, they and their end users will benefit from more capable connected solutions.

When 2G, the second generation of cellular communication technology, was commercially launched in 1991, its use of digital communication technologies rather than analog ones ushered in a new era of cellular communication with the introduction of data transfers and text messages. 3G followed in its footsteps, stepping up data rates and bringing us the mobile broadband experience we as consumers now take for granted.

But as the sun sets on 2G and 3G, it isn’t their initial beneficiaries — mobile phone users — that will be most affected. Over the course of three decades, their low cost of ownership, ubiquitous coverage and widespread roaming agreements have made 2G, and to some extent 3G, essential enablers of the Internet of Things.

Automotive emergency call systems, smart meters, vehicle telematics devices and tracking solutions are just a sampling of use cases that commonly continue to rely on 2G and 3G — and that will need to be upgraded as the technologies wind down.

Fortunately, the immediate inconvenience this will cause businesses and end users comes with a clear silver lining: not only will upgrading legacy solutions keep them from becoming obsolete along with the legacy networks they rely on, it will also allow IoT product developers and solution providers to tap into the value that today’s more advanced communication technologies provide, both to their and their customers’ benefit.

The sun begins to set

According to a GSMA report focusing on the Asia–Pacific region¹, the main considerations driving mobile network operators to sunset their 2G and 3G networks are cost reductions achievable by reallocating 2G and 3G spectrum to 4G and 5G. At the same time, mobile network operators (MNOs) are rightly wary to abandon 2G and 3G until both their own infrastructure and their customers’ solutions are prepared for the transition.

Because of regional variations of these opposing forces, sunsetting timelines vary from country to country (and even within individual countries, from operator to operator).

In North America, for example, US mobile network operators have been phasing out their 2G networks, and 2022 saw major 3G networks shut down their service, while Canadian MNOs will likely delay the transition to 2025.² The timelines are less aggressive in Central and South America, where at least some networks will continue to provide 2G and 3G service until more modern technologies have sufficient coverage to absorb demand.

In EMEA, where the installed base of 2G IoT devices is high, MNOs are pushing out 2G sunsets beyond 2025. Instead, 3G will by and large be the first to go. Enabled by a viable transition path from 3G voice services to newer technologies, many MNOs have already largely decommissioned their 3G services.

Finally, in the Asia–Pacific market, the transition strategy varies broadly from country to country, with markets where legacy 2G IoT devices are prevalent such as India expected to keep 2G networks up and running for longer. Others such as Singapore, New Zealand and Australia have already decommissioned their 2G networks. Generally, the timing of 3G sunsets will depend on the availability of alternative technologies capable of absorbing voice-based applications that are currently enabled by 3G.

Figure 1: Countries where at least one MNO has announced a 2G shutdown before 2025.
 

Figure 2: Countries where at least one MNO has announced a 3G shutdown before 2025.

4G is ready to pick up the slack...

With 2G and 3G on their way out, a common question will be whether to upgrade IoT devices to 4G LTE or whether to move straight to 5G. After all, 5G technology was specifically specced to meet the needs of a broad spectrum of use cases, including lightning-fast enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC) and, tailored to the needs of the IoT, massive machine-type communication (mMTC).

But because IoT applications need neither the high data rates offered by eMBB nor the ultra-reliable low-latency performance offered by URLLC, the choice ultimately comes down to four potential candidates — see Table 1.

Low bandwidth (currently served by 2G)	Medium bandwidth (currently served by 3G)
4G LPWA (LTE-M or NB-IoT)	4G LTE Cat 1(bis) or LTE Cat 4
5G mMTC	5G RedCap

Table 1.

Considering that LTE-M and NB-IoT are 5G-ready technologies, meaning that they are included in the 5G spec and will continue to work on 5G mMTC networks once they are available, it becomes clear that LTE-M and NB-IoT offer the best of both worlds for use cases requiring low data rates.

The picture is even more clear-cut when it comes to use cases requiring medium data rates. The 5G spec covering these use cases, 5G RedCap, will only be completed later this year, and the first devices supporting the technology won’t hit the market until around 2025. Consequently, LTE Cat 1 (and where available, its stripped-down, lower-cost variant LTE Cat 1bis) will become the go-to solution for use cases requiring medium data rates.

...and provide connectivity for the foreseeable future

But first, is it wise to bet on an already 12-year-old technology to offer the longevity expected for professional applications? If past generations of mobile communication technology offer any insights, it is that each generation tends to outlive the devices it connects by a large margin. 2G, which saw its first shutdowns 25 years after it first rolled out, continues to represent 15% of global connections. 3G was intended to replace 2G, in the same way that 4G was to replace 3G.

Today, 2G, 3G and 4G LTE coexist with 5G, which was launched with the explicit goal of complementing, not replacing, 4G LTE. 4G LTE is still growing its footprint, so it’s safe to say that it is not only ready to pick up the slack as 2G and 3G phase out, it will also continue to deliver reliable connectivity well beyond the expected lifetime of IoT devices.

NB-IoT, LTE-M or LTE Cat 1(bis)?

The optimal choice of cellular technology will always be the one that best meets use case-specific requirements in terms of network availability, data throughput, power consumption and latency. Mobile use cases further require seamless handovers from one cell tower to the next, as well as roaming agreements for uninterrupted connectivity across national borders. And device developers targeting global markets with their products might prefer the simplified logistics offered by devices that work out of the box wherever they are deployed.

Figure 3 breaks down the application space according to data rate requirements and geographical coverage.

Figure 3.

NB-IoT: Static low-data-rate IoT use cases located in areas with NB-IoT network coverage will benefit from the technology’s ultralow-power demand, low cost of ownership and extended range compared to standard 4G LTE technologies. Typical use cases include smart metering, smart buildings and smart cities, as well as agricultural and environmental sensing.

LTE-M: Mobile and static low-data-rate use cases located in areas with the required network coverage will be well served with LTE-M, with its low power requirements, extended range over standard 4G LTE and seamless handover from one cell tower to the next.

LTE Cat 1: Most mobile and static use cases with low to medium data rate requirements will see their needs met by LTE Cat 1, which today comes closest to offering the robust coverage with seamless handovers and international roaming agreements that many mobile 2G and 3G solutions rely on. In addition to offering the lowest latencies in this cohort, LTE Cat 1, which supports receive diversity via two separate receive pathways, is designed to carry high-quality voice communication and deliver reliable performance in difficult coverage conditions. Because LTE Cat 1 is already available on most 4G LTE networks worldwide, with robust international roaming agreements, businesses can simplify their logistics by serving global markets using a single stock-keeping unit (SKU).

Cost-sensitive applications with weaker coverage requirements that do not require highly reliable communication can alternatively use a stripped-down variant of LTE Cat 1, LTE Cat 1bis. Supporting only a single receive antenna, LTE Cat 1bis offers the same data rates and mobility as LTE Cat 1, wherever it is supported by mobile network operators.

Finally, use cases with even higher bandwidth requirements (data speeds above 10 Mbps download, 5 Mbps upload) can migrate solutions to LTE Cat 4 or higher.

More than just a technology upgrade

The forced migration to 4G will push customers to leave technologies that were not developed with the IoT in mind. As a result, it comes with a clear silver lining — generally speaking, it will enable end devices to do more with less:

• The new 4G technologies are, by design, much more power-efficient than the ones they are replacing, enabling up to 10 years of power autonomy. Gains in power autonomy translate directly to reduced maintenance and replacement costs.
• Their increased spectral efficiency allows them to efficiently deliver higher data rates, both for upload and download.
• Deeper in-building penetration allows them to meet the needs of more diverse use cases, in particular in metering applications.
• Finally, 4G provides a robust replacement to the lost global 2G/3G coverage.
   

As a result, the improvements brought by NB-IoT, LTE-M and LTE Cat 1(bis) and the improved end-device performance they enable will futureproof existing use cases while at the same time increasing customer satisfaction. At the same time, it will enable new applications that were poorly served by 2G and 3G.

Summary

As mobile network operators rationalise their cellular communication infrastructure to free up resources needed to expand their 5G coverage, IoT device developers and IoT service providers are being forced to migrate their 2G- and 3G-based solutions to futureproof alternatives.

NB-IoT, LTE-M and LTE Cat 1(bis) offer the most viable migration paths for existing IoT solutions based on 2G and 3G technology. While the applicability of NB-IoT is limited to static low-data-rate solutions, LTE-M and LTE Cat 1 (and LTE Cat 1 bis) are strong candidates to replace 2G and 3G modems for applications requiring voice communication, seamless handovers and international roaming.

Due to the near-universal availability of LTE networks, LTE Cat 1 paired with an IoT SIM card enabling global roaming is particularly well adapted for devices serving global markets.

The takeaway for everyone whose business is affected by the 2G and 3G network shutdowns is clear: 4G LTE — NB-IoT, LTE-M, and LTE Cat 1(bis) — is ready to pick up the slack and deliver robust connectivity for the foreseeable future, offering businesses new growth opportunities and end customers a better user experience.

*Drazen Drinic is an electrical engineer from the Technical University in Dortmund, Germany. He has over 20 years’ experience working in various product management roles in telecom infrastructure and energy and automation technology.

<sub>1. https://www.gsma.com/spectrum/wp-content/uploads/2020/06/Legacy-mobile-network-rationalisation.pdf
2. https://northernbi.com/3g-sunset-update-for-us-and-canadian-network-carriers/</sub>

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