NB-IoT and Cat-M1 vs. Cat-1: How To Choose The Right LTE IoT Standard

Companies that plan to implement IoT globally or need an upgrade path from existing 2G and 3G cellular network deployments have multiple LTE IoT standards to choose from.

First, there are two new LTE standards – NB-IoT, which stands for Narrow Band Internet of Things, and Cat-M1, which is also described as LTE-M – that are designed for IoT, have generated a lot of buzz and have been touted as the technologies that will drive the next generation of cellular IoT deployments. Carriers have begun to deploy these two standards.

Then there’s a third option that you may not have heard of, but it best fits global IoT deployments today: an LTE standard called Category 1 (Cat-1).

Read on, and we will explain the basics of the three standards, examine their benefits and limitations and then detail the reasons why you should consider Cat-1.

What is NB-IoT?

NB-IoT is a standard developed by the Third Generation Partnership Project (3GPP) as part of Release 13 of the LTE standard for cellular communications. It is a low-power, wide area network (LPWAN) technology that operates on the licensed spectrum and is designed for IoT devices with low-bandwidth needs.

It is low cost, provides improved in-building coverage, consumes less power, and thus, has a longer battery life when compared to other existing cellular standards.

NB-IoT features uplink speeds of 66kbps and download speeds of 26kbps in half-duplex mode, meaning data goes in one direction at a time. It also has a latency of 1.6 to 10 seconds.

NB-IoT operates in a very narrow bandwidth – 180 kHz – and can be deployed in the guard band portion of an LTE network, which is in-between channels in an unused portion of the spectrum.

As a result, it’s best suited for simple IoT devices that require small, intermittent data transmissions where latency doesn’t matter.

The cellular technology offers long-range support and strong signal penetration, so it’s good for long distances and indoor or underground usage. But NB-IoT can only be used for stationary IoT applications because it doesn’t handle cellular tower handoffs.

Applications for NB-IoT include smart gas, water, and electricity meters, smart city applications, such as smart street lighting and parking sensors, and other remote sensing applications that don’t send frequent or large amounts of data. That includes HVAC control, industrial monitors and agricultural sensors that monitor irrigation systems and detect leaks.

What is Cat-M1? 

Cat-M1, also known as LTE-M, is also a low-cost LPWAN technology developed by 3GPP as part of Release 13 of the LTE standard. It is a complementary technology to NB-IoT, it’s faster with 1Mbps upload and download speeds and a lower latency of 10 to 15 milliseconds.

Cat-M1 offers fast enough bandwidth to serve as a replacement for many current 2G and 3G IoT applications. It is different than NB-IoT in several other ways: Cat-M1 supports cellular tower handoffs, so it works with mobile applications, such as asset tracking and fleet management. It also supports voice features in IoT applications, such as medical alert devices and home alarm systems where the ability for people to talk is important.

The standard, which uses 1.4 MHz of bandwidth, also has enough throughput to transfer firmware, software and other security updates to IoT devices, including a full-blown Linux operating system – something NB-IoT can’t do. Furthermore, Cat-M1 supports full and half-duplexing, meaning companies can lower power consumption and increase their battery life by choosing half duplex.

Good Applications for Cat-M1 include wearables, such as fitness bands and smartwatches and automated teller machines (ATMs) in addition to asset tracking, health monitors and alarms. It also has some crossover with NB-IoT and can work with smart meters and industrial monitors.

What is Cat-1?

Cat-1 is designed for IoT devices with low and medium bandwidth needs. It is part of Release 8 of the 3GPP standard, so it’s an older, but still current technology.

Cat-1 – which has widespread adoption among carriers worldwide – offers bandwidth speeds of 5Mbps for uploads and 10Mbps for downloads with a latency of 50 to 100 milliseconds. It uses up to 20 MHz of bandwidth in full duplex mode and supports tower handoff.

The upshot: Cat-1 can manage the low-power applications that NB-IoT and Cat-M1 support, but it can also support higher bandwidth needs because it offers better performance and much lower latency than its two counterparts. On the flip side, Cat-1 consumes more power and has a slightly shorter signal range than NB-IoT and Cat-M1.

Cat-1, which also supports voice and mobile IoT applications, also offers a good migration path for 2G and 3G applications, such as asset tracking, smart meters, and other remote sensors.

Other good Applications include wearables, point-of-sale terminals, ATMs, retail kiosks, video surveillance, connected healthcare, consumer electronic devices, and some vehicle telematics data. It also supports shared mobility uses, such as bike and scooter rentals, and sophisticated IoT devices, such as digital signage and autonomous drones for deliveries.

Cat-1 isn’t fast enough to support the needs of autonomous vehicles of the future, however. For higher bandwidth needs, the Cat-4 LTE standard reaches 50Mbps upload and 150Mbps download speeds and can better handle video surveillance and other real-time video applications as well as in-car hotspots and in-car infotainment.

The future 5G cellular networks provide the high-speed, low-latency communications necessary to support autonomous vehicles, remote surgery in healthcare, and other high-bandwidth applications in the future.

The Reality and Current Limitations NB-IoT and Cat-M1 (LTE-M)

Researchers expect steady adoption of IoT devices running on NB-IoT and Cat-M1 networks as more carriers implement the two technologies in the coming years.

In fact, by the end of 2025, NB-IoT and Cat-M1 are expected to make up 52% of all cellular IoT connections, according to the Ericsson Mobility Report in November 2019. Similarly, in a separate study, analyst firm ABI Research predicts that by 2026, NB-IoT and Cat-M1 will account for 60 percent of the 3.6 billion LPWAN connections.

But while NB-IoT and Cat-M1 offer many benefits, the two technologies currently have some limitations, namely, they are still emerging technologies, and coverage is still limited globally.

Global reach and roaming capabilities. Carriers throughout North America, Europe, and Asia have begun adopting one or the other, but because NB-IoT and Cat-M1 are complementary technologies, some carriers are choosing to support both. In fact, out of 114 service providers that have deployed either NB-IoT or Cat-M1, nearly 25 percent have implemented both as of November 2019, according to the Ericsson Mobility Report.

However, while carriers are making progress with the adoption of NB-IoT and Cat-M1, they are not widely deployed globally yet. That, in turn, limits roaming capabilities. If your company has a specific IoT Applications that requires roaming between carriers on Cat-M1 networks today, it may not be possible because of the still limited adoption rates.

Is it really low-power? NB-IoT and Cat-M1 do, in fact, consume less power than previous cellular technologies, such as Cat-1, 2G and 3G networks. The new standards also include some additional power-saving features that can further reduce power consumption and extend the battery life of IoT devices. However, these highly touted features may not live up to their promises because carriers might not fully support them.

More specifically, NB-IoT and Cat-M1 devices can sleep for a longer period of time through two features: Power Saving Mode (PSM) and Extended Discontinuous Reception (eDRX). With PSM, IoT devices using NB-IoT and Cat-M1 can go dormant indefinitely and then wake up at a pre-determined time to send and receive data.

With eDRX, IoT devices can increase the paging cycle from the normal 1.28-second interval to 10.24 seconds. The eDRX technology enables IoT devices to sleep a pre-defined number of hyper frames or multiples of those 10.24 seconds, and as a result, NB-IoT devices can sleep up to three hours, while Cat-M1 devices can sleep up to 40 minutes.

However, there are potential limits to the amount of power saved by eDRX and PSM because their usage is not solely dictated by IoT devices. In fact, it depends on each specific carrier and whether each carrier supports all the available low-power modes. It’s likely that carriers may only adopt a subset of the low-power modes, meaning IoT devices may not fully maximize the benefits of eDRX and PSM.

Why Cat-1 Is The Best Choice Today

Companies that need to deploy IoT globally today should consider Cat-1 because the two new alternatives – Cat-M1 and NB-IoT – are simply not yet ready for prime time in most markets.

In contrast, Cat-1 is available today and widely supported by carriers worldwide. Its low cost and popular for IoT deployments and is about the same price as current Cat-M1 and NB-IoT modules. And while it does use more power than Cat-M1 and NB-IoT, it does use reasonably low power and support longer distances.

Power savings does matter. But one way to look at it is this: 2G and 3G are not low-power technologies. With 2G and 3G networks shutting down, companies that need to upgrade their IoT deployments will find that Cat-1 is more energy-efficient than the older 2G and 3G networks.

Cat-M1 and NB-IoT are the future – no doubt. In fact, the 3GPP plans to evolve NB-IoT and Cat-M1 and merge them into the 5G standard.

But Cat-1 – and LTE in general – are not going away anytime soon. Carriers are still in the early stages of building 5G networks, and as a result, LTE networks will remain the de facto standard for several years at least. And even after that, LTE networks and Cat-1 will remain and not get phased out for some time.

Simply put, companies that need to deploy IoT globally today or upgrade from 2G and 3G networks can’t wait for Cat-M1 and NB-IoT to expand globally and mature as a technology. Cat-1 is a viable, strong solution today and for years to come, and provides the most extensive, thorough coverage for your current IoT needs.