Choosing LTE Standards
When you’re designing a cellular IoT product, you must plan for connectivity from the very start. Immediately, you’re faced with a tough choice: choosing LTE standards. Which 4G LTE (or 5G NR) standard should you design for? The answer will dictate the path of your connectivity technology, from which chipsets and modules to use to the mobile network carriers you work with.
If you’re designing for massive IoT deployments—anything from smart utility meters to wearable consumer devices to industrial autonomous vehicles—LTE cellular networks give you four choices. (These are likely to change as we approach 2030, as 4G LTE networks give way to 5G New Radio [NR]…but we’ll discuss that transition, and its implications for device manufacturers, in another article.) For now, keep reading for tips on which LTE standard will provide the most value for your products, including common use cases for each.
The 4 LTE Standards for Massive IoT
Today’s massive IoT connectivity ecosystem offers these LTE standards, each of which is appropriate for a different set of scenarios. Here are today’s choices, along with a few standard applications for each:
1. LTE Cat 1
Long-term evolution (LTE) networks specify size limits for data as it travels across cellular networks. In 2008, standardization authority 3GPP published Release 8, which defined specifications for user equipment (UE) along five categories.
The first of these categories—LTE Cat 1—defines a maximum data transfer rate of five megabytes per second for uploads (5 Mbps UL), and 10 Mbps for downloads (10 Mbps DL). That made LTE Cat 1 the first standard designed specifically for IoT, which typically demands lower data rates than, say, streaming Netflix on your phone.
You might think a standard that first appeared in 2008 is outdated. In fact, the opposite is true: Because LTE Cat 1 is a mature technology, it’s available essentially everywhere, and it provides enough data throughput to support a wide variety of use cases. That’s not always the case, as we’ll discuss in our coverage of NB-IoT and Cat-M, items three and four on this list.
2. LTE Cat 1bis
An LTE Cat 1 module uses two antennas. For device manufacturers looking to save space or cut costs, one antenna may be more appropriate. Enter LTE Cat 1bis, which is essentially a version of the LTE Cat 1 standard (5 Mbps UL and 10 Mbps DL) on single-antenna hardware.
A Cat 1bis module may lose some coverage compared to its dual-antennaed cousin, but the difference rarely translates to the user’s experience. When Sequans—producers of the Calliope chipset, the first LTE platform optimized for Cat 1—conducted field tests, they found that the single antenna lost only a few decibels of coverage compared to a dual-antenna Cat 1 module and that the advanced signal processing techniques of the platform can mitigate this loss.
Furthermore, cellular networks are often uplink limited, resulting in customers experiencing little to no difference between the use of one or two antennas, as reported by millions of customers using only one antenna in real-world deployments. This shows the relevance of a Cat 1bis optimized platform providing cost improvements while providing nearly equivalent Cat 1 performance. Finally, it is important to stress that any Cat 1 network can enable Cat 1bis devices without any network change or upgrade.
All that makes LTE Cat 1bis an excellent choice for small devices with moderate data requirements, including voice or video data.
Common IoT Use Cases for LTE Cat 1 and LTE Cat 1bis
Because they use essentially the same baseline specification, LTE Cat 1 and Cat 1bis cover the same types of applications. The difference is whether a single-antenna design will fit your product better, due to savings in space or cost. (The benefits will vary from project to project, which is why it’s helpful to choose a chip/module provider with the expertise to help guide you to your ideal technology). Also, when using a new generation dedicated Cat 1bis module, one can benefit from the most optimized RF and power consumption performance, along with additional features like integrated GNSS or integrated eSIM.
These standards offer near-universal coverage, along with higher data limits than NB-IoT or LTE-M. That makes them particularly flexible for devices with varying data throughput needs and/or multinational deployments. Common use cases for LTE Cat 1 include:
- IoT retail kiosks
- In-car hotspots
- Gaming devices
- SmartGrid products
- Home security systems
- Wearable cameras
- Point-of-Sales terminals
- Health monitors
- Smart watches
For lower data needs, however, 3GPP does offer two LTE standards designed specifically for massive IoT projects: NB-IoT and LTE-M.
By 2015, the IoT industry was looking for lower-cost chipsets and modules. Many IoT systems didn’t need anywhere close to 5 Mbps UL or 10 Mbps DL data rates. That need led to the development of two IoT standards for LPWANs, as defined in 3GPP’s Release 13.
The Narrow Band Internet of Things (NB-IoT) standard was designed specifically for IoT devices with low data requirements. It limits data rates to around 160 kilobytes per second (kbps) in 3GPP Release 14. If you don’t need to move much data, NB-IoT’s low data rates can help optimize your IoT products for cost, power usage, and network capacity—provided your market carries NB-IoT coverage.
Both NB-IoT and LTE-M require upgrades to cellular networks, which has led to non-uniform deployment, globally. In China, India, and parts of Europe, NB-IoT is widely available.
Common IoT Use Cases for NB-IoT
Because NB-IoT offers the lowest data limit among all four LTE standards, use cases are limited to the sorts of sensors that transmit very small packets. These often include:
- Smart smoke detectors
- Parking control systems
- Agricultural monitoring products
- Smart building applications (HVAC and lighting control, for instance)
- Pollution monitoring systems
- Industrial IoT sensors
- Part of the metering applications (notably gas and water)
The LTE-M standard sits somewhere between NB-IoT and Cat 1 in terms of data limits; it allows up to 1.1 Mbps of data to flow. Other than that, it’s quite similar to NB-IoT: optimized for cost, power usage, and network capacity for massive IoT systems.
However, some regions of the world updated their cellular infrastructure for NB-IoT, not LTE-M, so it’s not available everywhere. In North America, Japan, and—again—parts of Europe, LTE-M is widely and functionally deployed, but it’s not available at all in China or India.
As we mentioned, Cat 1 is available on virtually every cellular network in the world. If you serve global markets—and you don’t want the inventory headache of managing multiple SKUs for the same product—Cat 1 is probably your best choice. But if your data needs fall between the NB-IoT and the Cat 1 limits, and your markets have coverage, LTE-M can offer a great combination of benefits in massive IoT deployments.
Common IoT Use Cases for LTE-M
Where it’s available, LTE-M is a popular standard for smart city applications, which typically require low latency, but don’t have high data needs. This standard is also used for light asset tracking and monitoring, plus some smart devices. Sample use cases for LTE-M connectivity include:
- Fleet trackers
- Asset trackers
- Utility meters (gas, electricity, water, etc.)
- Mobile personal emergency response systems (mPERS)
There’s also a lot of overlap between the use cases for LTE-M and Cat 1. The LTE-M standard is also found in connected healthcare devices, smart watches, and point-of-sales terminals, for instance.
This area of commonality between LTE-M and Cat 1 leads to another question: How do you determine which LTE standard is right for your product or project?
5 Questions to Help Identify the Right LTE Standard
Every massive IoT project is different, and any of these four LTE standards may provide the most benefits for yours. To make the right decision, start by answering these five questions:
- What are your goals for cellular connectivity?
Start by identifying your key performance indicators (KPIs). What do you need the cellular connection to do? Must it be optimized for higher data throughput, lower power usage, minimal latency, reliable uptime, or some combination of these factors? Once you set your goals, you can start making a plan to meet them—but always keep the goalpost in mind.
- How much are you willing to spend?
Clearly, limiting costs is essential to any product’s development. But to get all the features you want into an IoT device, you may need to adjust your cost targets. When pricing out your cellular connectivity, consider both the cost of the module and the ongoing cost of your data plan.
- What is your project timeline?
Adding cellular connectivity to your products requires assembly, testing, and relationships with MNOs, and your choice of standard can affect these timelines. If you need to ship your product sooner rather than later, that could change your choice of cellular technology.
- Where do you plan to deploy your IoT devices?
As noted above, NB-IoT and LTE-M aren’t available everywhere in the world, although they are very mature in some regions, and one can consider using a dual-mode LTE-M/NB-IoT solution. If you cover a global market, you have two choices: You can either manage multiple SKUs for each region (and its corresponding LTE standard), or you can go with the global coverage of Cat 1 or Cat 1bis.
- How much future-proofing do you need?
Be realistic about your product’s lifespan. If you need it to work for 20 years and are not expecting to launch before 2027, for instance, you may need to wait for the coming switch to 5G NR networks. (We expect to see that transition begin around the late middle of the 2020s.) That said, we expect LTE-M and NB-IoT to coexist with 5G NR at least through 2035, and private LTE operators will keep it way beyond 2040—the point being, knowing how long your product needs to work in the field can help you choose the right cellular standard.
If all this seems confusing, that’s because it is! The most helpful tip we can offer is to source your chipsets and modules from a provider that backs up their products with expert consultation. Chipset producers are the experts in cellular connectivity; work with them to make the best choice for your massive IoT products.