NB-IoT, Cat-M1 (LTE-M) and Cat-1: How to choose the right LTE IoT standard

Companies that plan to implement IoT globally, have multiple LTE IoT standards to choose from. First, there are two newer LTE standards. NB-IoT (Narrow Band Internet of Things, and Cat-M1 (also called LTE-M) are designed for IoT. Both have generated a lot of buzz and have been touted as the technologies that will drive the next generation of cellular IoT deployments. As such, carriers have begun to deploy these two standards.

Then there's a third option that you may not have heard of but is a great fit for 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 you should consider Cat-1.

Key takeaways

• NB-IoT supports only stationary devices with speeds of 26-66 kbps and latency of 1.6-10 seconds, while Cat-M1 enables mobile applications with 1 Mbps speeds and 10-15 ms latency.
• Cat-1 offers the widest global carrier coverage today with 10 Mbps download speeds, making it the most practical choice for companies deploying IoT internationally or migrating from 2G/3G networks.
• Power-saving features like PSM and eDRX in NB-IoT and Cat-M1 may not deliver full battery life benefits because carrier support for these modes varies.

What is NB-IoT?

NB-IoT (Narrow Band Internet of Things) is a low-power, wide-area network (LPWAN) cellular technology designed for stationary IoT devices that transmit small amounts of data infrequently. Developed by 3GPP as part of LTE Release 13, it operates on licensed spectrum with a narrow 200kHz bandwidth, making it ideal for battery-powered sensors and meters in hard-to-reach locations.

NB-IoT features

NB-IoT is a subset of the LTE standard, constrained to a single 200kHz narrow-band. Key benefits include:

• Low cost: Simplified hardware reduces module pricing
• Extended battery life: Lower power consumption than other cellular standards
• Strong signal penetration: Improved coverage for indoor and underground deployments

NB-IoT uplink and download speeds

When thinking about IoT applications, the speed at which data can be uploaded to the internet and downloaded from the internet will be an important consideration. 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.

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

NB-IoT bandwidth

As mentioned, NB-IoT operates in a very narrow bandwidth 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. It has a 200 kHz channel bandwidth but occupies only 180 kHz.

NB-IoT use cases

NB-IoT works well for long distances and indoor or underground usage due to its strong signal penetration. However, it only supports stationary applications because it can't handle cellular tower handoffs.

Common use cases include:

• Smart gas, water, and electricity meters
• Smart city applications (street lighting, parking sensors)
• HVAC control and industrial monitors
• Agricultural sensors for irrigation and leak detection

What is Cat-M1 (or LTE-M)?

Cat-M1, also known as LTE-M , was designed specifically for IoT projects to transfer low to medium amounts of data (200 – 400 kbps) across a wide geographical range. It was designed to exist as an alternative to unlicensed LPWAN options, like LoRa, SigFox, and RPMA. Let's dive into the features of LTE-M to see how it compares to NB-IoT.

Cat-M1 features

Cat-M1 is also a low-cost LPWAN technology developed by 3GPP as part of Release 13 of the LTE standard. It's a complementary technology to NB-IoT and also features low power; however, it's different from NB-IoT in several ways. For one, Cat-M1 supports cellular tower handoffs, so it works for mobile applications, such as asset tracking and fleet management. It also supports voice features in IoT applications, making it a good choice for medical alert devices and home alarm systems where the ability for people to talk is important.

Cat-M1 uplink/download speed

LTE-M offers peak speeds of 1Mbps for both upload and download, with typical throughput of300 kbps downlink and 380 kbps uplink. Latency ranges from 10 to 15 milliseconds—significantly faster than NB-IoT. This makes Cat-M1 well-suited for IoT applications where consistent data value matters more than raw speed.

Cat-M1 bandwidth

Cat-M1 offers fast enough bandwidth to serve as a replacement for many current 2G and 3G IoT applications. 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.

Cat-M1 use cases

Cat-M1 supports mobile and voice-enabled applications, including:

• Wearables (fitness bands, smartwatches)
• Asset tracking and fleet management
• Health monitors and medical alert devices
• ATMs and home alarm systems
• Smart meters and industrial monitors

What is Cat-1?

Now, let's look at a third IoT standard, Cat-1, and some of its features that make it such an attractive option for IoT LTE deployment.

Features of Cat-1

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

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 uplink/download speed and bandwidth

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.

Cat-1, which 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.

Cat-1 use cases

Good use cases include wearables, point-of-sale terminals, ATMs, retail kiosks, video surveillance, connected healthcare, consumer electronic devices, and some vehicle telematic 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.

However, Cat-1 isn't fast enough to support the needs of autonomous vehicles of the future. 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.

The reality and current limitation of NB-IoT and Cat-M1

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.

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. The momentum is clear: according to GSMA Intelligence, NB-IoT and Cat-M1 connections are projected to reach over 800 million globally by 2030.

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 use case that requires roaming between carriers on Cat-M1 networks today, it may not be possible because of the still limited adoption rates.

Limited use cases

As mentioned, NB-IoT can't accommodate cellular tower handoffs, and this is one of the main reasons it's best for stationary objects. When it comes to IoT deployment, this limits the use cases and results in fewer applications.

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.

NB-IoT and Cat-M1 devices achieve longer sleep cycles through two features:

• Power Saving Mode (PSM): Devices go dormant indefinitely, waking at pre-determined times to transmit data
• Extended Discontinuous Reception (eDRX): Extends paging cycles from 1.28 seconds to 10.24 seconds, allowing NB-IoT devices to sleep up to three hours and Cat-M1 devices 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.

Which connectivity option is the best choice today?

Even though Cat-M1 (LTE-M) and NB-IoT are starting to get widely deployed, CAT-1 will probably be the best option for most deployments. Let's take a look at a few reasons why.

Availability

Companies that need to deploy IoT globally today should consider Cat-1 because the two new alternatives are simply not as widely available (though this may soon change).

In contrast, Cat-1 is available today and is widely supported by carriers worldwide. It's low cost, 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 supports long distances.

More energy efficient compared to previous networks

Power savings does matter, and enhancing this is something to look forward to when Cat-M1, or LTE-M, and NB-IoT are more readily available. But one way to look at it is this: 2G and 3G are not low-power technologies. Companies that need to upgrade their IoT deployments will find that Cat-1 is more energy-efficient than the older 2G and 3G networks.

Timeline

Cat-M1 and NB-IoT represent the future of cellular IoT and 3GPP plans to merge both into the 5G standard. However, Cat-1 and LTE networks aren't going away anytime soon as carriers continue building out 5G infrastructure. Cat-1 delivers the widest coverage without waiting for newer standards to mature. It's a reliable, proven solution that meets current IoT needs while remaining viable for years to come.

Frequently asked questions

What is the main difference between NB-IoT and Cat-M1?

NB-IoT only supports stationary devices because it cannot handle cellular tower handoffs, while Cat-M1 supports mobile applications and voice features with faster speeds of 1Mbps versus NB-IoT's 26-66 kbps.

Which LTE IoT standard has the widest global coverage today?

Cat-1 has the widest global coverage as it is widely deployed by carriers worldwide, while NB-IoT and Cat-M1 are still emerging technologies with limited availability in many regions.

Can NB-IoT be used for asset tracking?

No, NB-IoT cannot be used for asset tracking because it does not support cellular tower handoffs, making it suitable only for stationary applications like smart meters and sensors.

What is the upload speed of Cat-M1?

Cat-M1 offers typical upload speeds of 380 kbps with peak speeds reaching 1 Mbps, which is fast enough to transfer firmware updates and security patches to IoT devices.

Do carriers fully support the power-saving features of NB-IoT and Cat-M1?

Not all carriers support the full range of power-saving modes like PSM and eDRX, meaning IoT devices may not achieve the maximum battery life benefits advertised for these technologies.

What bandwidth does Cat-1 use compared to NB-IoT?

Cat-1 uses up to 20 MHz of bandwidth in full-duplex mode, while NB-IoT operates in a narrow 200 kHz channel, making Cat-1 suitable for higher bandwidth applications.

Which LTE IoT standard supports voice calls?

Both Cat-M1 and Cat-1 support voice features, making them suitable for medical alert devices and home alarm systems, while NB-IoT does not support voice.

What is the latency of NB-IoT?

NB-IoT has a latency of 1.6 to 10 seconds, which makes it unsuitable for real-time applications but acceptable for simple sensors that transmit data infrequently.

Is Cat-1 being phased out with the arrival of 5G?

No, Cat-1 and LTE networks will remain viable for years as carriers continue building out 5G infrastructure, making Cat-1 a reliable choice for current IoT deployments.