NB-IoT for M2M and IoT: Everything You Need to Know

Eseye

IoT Hardware and Connectivity Specialists

LinkedIn

Of the dozen or so categories of LTE with M2M and IoT use cases, NarrowBand-Internet of Things (NB-IoT) is one of the most well known and most widely deployed, alongside LTE-M and Cat-1 (bis).

NB-IoT (also known as LTE Cat-NB1) is a member of the family of Low-Power Wide-Area Network (LPWAN) technology standards developed by 3GPP, with the specification frozen in 3GPP Release 13, known as LTE Advanced Pro, in 2016.

This article goes into a deep dive of the pros and cons of NB-IoT, and is part of a series of articles comparing LTE-M to NB-IoT and LTE Cat-1 (bis) to help you understand the most appropriate technology for your use case.

NB-IoT explained

NB-IoT is a low-power narrowband technology that does not use a traditional LTE physical layer but is designed to operate in or around LTE bands and coexist with other LTE devices, including in unused guard bands between LTE channels.

NB-IoT was developed to enable a wide range of new IoT devices and services, and benefits from a longer range than comparable technologies, including better penetration through environmental obstacles such as walls, and metal and plastic conduits, at the compromise of lower low data transfer rates. This can limit the types of applications supported by NB-IoT, and also excludes voice and video capabilities.

The downlink rate for NB-IoT devices is also much lower than other technologies and measured in Kilobits per second, exempting them from device updates. This can have a significant impact on device longevity and future proofing, which is a key consideration for long-term deployments. A lack of SMS support also prevents NB-IoT devices from being able to receive SIM updates and profile switches.

On the plus side, NB-IoT does consume less power than other technologies, which enables a longer battery life when compared to other existing cellular standards.

NB-IoT is also suitable for very low data rate applications, providing deep penetration and high-density connectivity, making it perfect for utility meters and smart city or smart building applications.

NB-IoT technology breakdown: features and capabilities

NB-IoT low power performance

NB-IoT was positioned as the enabler of very low power IoT applications, promising up to a decade of connectivity before a battery swap. This isn’t just a boastful claim – a battery life of more than 10 years can be supported in a wide range of use cases. But the caveat is that power consumption for IoT deployments is very deterministic and decisions made by individual mobile network operators (MNO) will always have a big impact.

Still, NB-IoT supports two key features that significantly enhance battery life by enabling devices to sleep for extended periods of time. Extended Discontinuous Reception (eDRX) and Power Saving Mode (PSM) both extend the timespan for the device waking up and checking for updates via radio, and let the device go to sleep for extended periods of time.

These features dramatically reduce power consumption, and make it possible for NB-IoT devices to approach that 10-year battery life.

Radio access

NB-IoT is largely supported by all major mobile equipment, chipset and module manufacturers, and can co-exist with 2G, 3G, and 4G networks. Historically however, interoperability issues between device manufacturers meant that multiple incompatible versions of the technology were in-market, and while these issues have been fixed, such rollout challenges drove operators to look at more coherent alternative ecosystems like LTE-M.  

As indicated by its name, NB-IoT operates in a narrow band of the licensed radio spectrum, with a channel bandwidth of 200 kHz but occupies only 180 kHz, equivalent to one resource block in LTE, potentially with a 10 kHz guard buffer on each side. This enables three modes of operation:

• Standalone operation – NB-IoT operates independently
• Guard band operation – NB-IoT operates in the guard bands of an LTE channel
• In-band operation – NB-IoT uses frequencies which are not used by LTE in the LTE channel bands

These characteristics mean NB-IoT can operate in unused 200 khz bands that were previously used by GSM, making it suitable for the re-farming of GSM spectrum.

Because NB-IoT is designed with bandwidth efficiency in mind, multiple NB-IoT networks can coexist in the same area with minimal interference, although densification eventually causes packet collisions and increased interference between devices and with adjacent LTE networks.

NB-IoT can support large numbers of devices (known as ‘massive IoT’) by establishing NB-IoT networks that can connect to billions of nodes, with support for up to 50,000 connections per network cell.

Repeated transmissions from base stations extend coverage further and give better support for indoor deployments, while NB-IoT signal strengths are typically strong enough to penetrate multiple layers of brick, or metal walls.

Half duplex, single antenna requirements keep devices simple and reduce complexity, but NB-IoT doesn’t support voice communications, or rich media like video due to bandwidth constraints.

For various reasons, some of which we go into in detail below, NB-IoT hasn’t seen the anticipated levels of adoption, limiting its accessibility worldwide.

Security

NB-IoT operates in licensed spectrum swathes and is considered highly secure. It also benefits from all the typical security and privacy features of cellular networks, such as support for user identity, authentication, confidentiality and privacy, encryption, data integrity, and equipment identification.

Mobility and roaming

Originally designed for largely static M2M and IoT use cases, NB-IoT doesn’t offer much support for device mobility. NB-IoT devices only remain connected within a designated cell and only to one network operator.

This limits its usefulness for highly mobile applications such as wearables, and can impact battery life if used in non-stationary applications – because a device has to reselect the cell if it moves, which increases the power draw.

NB-IoT also has limited support for roaming. The specification must be supported in each country a device is intended to connect in, meaning an IoT device could become inoperable if an operator doesn’t have a local presence.

A downside of poor adoption of NB-IoT universally means that operator support is limited to Russia, China, India, and pockets of Eastern Europe, Southeast Asia, Saudi Arabia, and South Africa. This can be seen on the GSMA maintained deployment map for IoT technologies here.

NB-IoT features

Limitations of NB-IoT

Despite its many positives that make NB-IoT look like a perfect choice for M2M and IoT deployments on paper, its real-world accessibility has been constrained by a series of limitations.

The most obvious of these is the lack of NB-IoT coverage around the world. Although it should be straightforward for mobile network operators to roll out NB-IoT networks, availability has remained limited, often with only one operator providing the service in each of the countries identified in the map above.

Furthermore, while some roaming agreements are in place, the ecosystem remains very fragmented and uncertain.

This in turn impacts device production, as businesses are frequently faced with a need to have multiple SKUs (Stock Keeping Units) – or versions of an IoT device that cater to different regional requirements – impacting costs and administrative overhead.

As mentioned previously, device mobility is an issue. NB-IoT devices only remain connected within a finite environment and only to one network operator.

Low data rates and high latency exempt NB-IoT products from any kind of rich media or time-sensitive applications, preventing voice and video, as well as live updates. This also means NB-IoT devices are incapable of receiving instructions to change SIM profiles or update firmware.

But perhaps the greatest limitations have come in the form of industry perceptions, and damage done to the NB-IoT ‘brand’. The initial issues about vendor interoperability, plus delays to standardization and other early-launch concerns, all led to NB-IoT being pronounced ‘dead’ several times over the last years.  

These concerns were enough to put operators off deployments on a global scale, and let competing solutions such as LTE-M and Cat-1 (bis) get an upper hand.

Another major blow dealt to the NB-IoT ecosystem in general is by nature of the fact that the unpredictable usage patterns, low amounts of data being transferred, and lack of mobility have made it difficult to create an end-to-end profitability chain for all participants in the ecosystem that warrants further investment or support. 

NB-IoT use cases

That said, NB-IoT has proved its usefulness, and while it has been deployed in tracking applications for assets that move, NB-IoT’s strength is more suited to fixed or mostly stationary assets. This is because an NB-IoT device needs to reselect cells as it travels (a drain on the battery), which isn’t the case with LTE-M.

Smart cities

NB-IoT is well-suited to smart city deployments and, by extension, smart buildings. The technology can help control street lighting, traffic lights and sensors, manage parking, waste disposal facilities, and monitor environmental conditions.

It also has an application for utilities in the case of smart metering for water, gas, or electricity. Essentially any application where the data payload is small and the IoT device needs to be placed inside a building or within some kind of structure.  

Smart buildings

In much the same way as they support smart cities, NB‑IoT devices can serve as sensors to help monitor buildings, with applications such as temperature monitors, lighting controls, fire and smoke detectors, intruder alarms and even water flow sensors to monitor water consumption.

Supply chain management

Although not appropriate for continuous monitoring of moving assets, NB-IoT could be used in logistics and supply chain management to track assets or inventory as it moves from A to B. The trade-off would be slightly reduced battery life and of course, it would only work on an international scale in limited territories that support the technology.

Agriculture

In much the same way as it supports smart cities, NB‑IoT connectivity could be used to support smart farming by enabling farmers to capture data from environmental sensors, such as weather, temperature, soil condition, pollution, and rainfall.

Is NB-IoT right for my IoT or M2M deployment?

Although NB-IoT was born amid lots of hype as a standardized technology intended to specifically support IoT and M2M deployments, its  adoption has lagged behind expectation and allowed alternatives like LTE-M to be established as frequently better options.

Although NB-IoT does have some advantages going for it: it’s cheap, relatively easy to deploy, provides great coverage and building penetration, and has good battery life, the benefits are not vastly different to other LPWAN technologies that bring additional enhancements to the table.

Ultimately, the runaway success of LTE-M has become a bit of a problem for NB-IoT. While LTE-M was intended to provide IoT support for assets that move and need better bandwidth, it also works in applications that are more on NB-IoT’s historical turf, especially as the cost of LTE-M devices continues to come down. LTE-M also benefits from wider global adoption.

Ultimately, if you’re now considering which IoT connectivity technology to deploy in devices that might have a lifespan of 10 years, NB-IoT doesn’t look to have much in the way of differentiation when compared to the potential of an alternative like LTE-M.

LTE-M for IoT and M2M

4G LTE-M technology is commonly used for IoT and M2M deployments. Find out everything you need to know about this technology, including a detailed breakdown of its features and capabilities.

Learn more

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Eseye

IoT Hardware and Connectivity Specialists

LinkedIn

Eseye brings decades of end-to-end expertise to integrate and optimise IoT connectivity delivering near 100% uptime. From idea to implementation and beyond, we deliver lasting value from IoT. Nobody does IoT better.

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