NB-IoT, or Narrowband-Internet of Things, is a cellular technology built to make wireless connectivity for Internet-of-Things (IoT) devices more accessible.
Think of it as a low-power network technology designed to connect devices that don’t need to send a lot of data but need to do it over long distances while running on a single battery for a very long time.
While NB-IoT offers benefits to many IoT devices, it is not ideal for all applications. This guide uniquely focuses on cases where NB-IoT might not be the optimal choice. This is useful for technical managers or those developing IoT devices for the first time, to see NB-IoT’s fit within the IoT stack.
We begin with an overview of NB-IoT before exploring how it performs in real-world use. You can jump ahead to the topics that interest you most.
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What is NB-IoT
NB-IoT is a cellular network standard developed by 3GPP that was finalized in June 2016 as part of Release 13 (LTE Advanced Pro).
Major technology companies and telecommunications providers, including Huawei, Ericsson, Qualcomm, and Vodafone, have reportedly collaborated with 3GPP to create and establish this standard.
Looking at the larger cellular technology landscape, NB-IoT is classified as:
- A low-power wide-area network (LPWAN) technology; that,
- Operates under a licensed spectrum.
You may also find others referring to NB-IoT as:
- Narrowband IoT, or
- LTE Cat NB (LTE category Narrowband)
NB-IoT evolution: LTE Cat-NB1 vs Cat-NB2
When NB-IoT (LTE Cat-NB1) was first rolled out, it aimed to provide a cost-effective, low-power, and wide-coverage solution for IoT applications. LTE Cat-NB2, introduced in 3GPP Release 14 (June 2017), improved upon this with better data rates, lower latency, and enhanced positioning capabilities.
What are the differences between NB1 and NB2 IoT?
Side-by-side, we can see how NB-IoT has evolved from Cat-NB1 to Cat-NB2.
| Feature | LTE Cat-NB1 (NB-IoT release 13) | LTE Cat-NB2 (NB-IoT release 14) |
|---|---|---|
| Uplink data rate | Up to 66 kbps | Up to 159 kbps |
| Downlink data rate | Up to 26 kbps | Up to 127 kbps |
| Bandwidth | 180 KHz carrier | 180 kHz carrier with improved modulation |
| Power consumption | Very low, supports PSM and eDRX | Low, supports PSM and eDRX with enhancements |
| Coverage | Good, deep indoor and rural areas | Good, with improved performance in challenging environments |
| Latency | Higher | Lower |
| Efficiency | Standard | Enhanced |
| Positioning | Basic (Cell-ID) | Enhanced (OTDOA, E-CID) |
Under the hood: NB-IoT technology and functionality
Why was NB-IoT developed? As described in the 3GPP standards, the primary purpose of NB-IoT is to extend the reach of cellular networks to efficiently support large-scale low-bandwidth, battery-powered devices through optimized capabilities.
Key features and capabilities of NB-IOT
Power-saving features
Supports Power Saving Mode (PSM) and extended Discontinuous Reception (eDRX), allowing devices to operate for years on a single battery.
Extended coverage
NB-IoT’s link budget (can support 164dB) enables deep indoor and outdoor coverage (see figure above).
Cost efficiency
Simplified device modules and lower bandwidth requirements reduce overall costs (pricing varies, approx. US$5 per module).
High capacity and scalability
Can support a high density of devices per cell tower (up to 50,000 connections per network cell), ideal for IoT deployments of scale.
Non-IP data delivery
The Service Capability Exposure Function (SCEF) is a network component that securely connects external apps to the network’s capabilities, enabling efficient transmission of non-IP data. (NIDD).
What are the limitations of NB-IoT?
NB-IoT adapts the existing LTE network for low-data, low-cost, and long-range IoT applications by prioritizing simplicity and low power use. It achieves this by omitting complex, power-heavy features, making it ideal for some, but not all, IoT use cases.
- Latency: NB-IoT has a latency of 1.6 to 10 seconds which may not be suitable for applications with critical real-time data transmissions.
- NB-IoT has no SMS and VoLTE capabilities: NB-IoT doesn’t come with built-in support for SMS messaging or VoLTE (only a few operators offer SMS). For example, SMS is a common fallback option for troubleshooting, and the lack of can make things more difficult.
- No roaming: Network providers generally don’t support roaming for NB-IoT. This is a major drawback for global deployments, as it limits seamless connectivity across various networks.
- Handover is not supported: Handover or handoff allows devices to switch seamlessly between cell towers while moving, but requires complex, power-intensive processes. NB-IoT prioritizes low power consumption, omitting this feature.
- Challenges to firmware updates: NB-IoT’s lower bandwidth can make over-the-air updates to devices slower or more challenging.
Additionally, NB-IoT requires additional hardware on cell towers, resulting in a slower rollout than anticipated. The deployment delays can be limiting for fleets requiring a widespread rollout.
Security considerations in NB-IoT
NB-IoT inherits the security features of cellular networks, including device authentication, data encryption, and secure communication protocols.
However, NB-IoT has a simplified design with limited resources (bandwidth and battery life) which limits the use of sophisticated security algorithms across network layers.
Additionally, research has found that device-to-device (D2D) communication in NB-IoT is vulnerable to eavesdropping and attacks from malicious actors.
It’s always good practice to implement additional security measures to mitigate potential vulnerabilities, regardless of network technology.
From deployment to devices: NB-IoT implementation and market
How does NB-IoT work? In a nutshell, it takes many of its core features and communication methods from LTE.
The main difference with LTE is that NB-IoT is simplified to keep costs and power usage low for IoT devices. This means:
- Smaller frequency band: For efficiency, the bandwidth is restricted to a narrow band of 180-200kHz (which is where it has likely derived its name from).
- High signal repetition: Allows for greater range and better indoor performance.
- Similar protocol structure, reduced features: The protocol stack of the base station (eNB) and the user device (UE) remains the same, but their features are simplified to reduce complexity (this likely contributes to energy efficiency when transmitting data).
However, NB-IoT’s wider coverage comes with tradeoffs.
Using less bandwidth means slower data speeds. And repeating transmissions more often leads to longer delays and puts strain on battery power. More on these tradeoffs later in this guide.
Operators deploying NB-IoT
Rolling out NB-IoT, operators deploy in three modes: in-band within an LTE carrier, in the LTE guard band, or as a standalone carrier.
The textbox below gives a detailed explanation of the three NB-IoT deployment modes.
💡 3 NB-IoT deployment modes
- In-band mode: Utilizes a single Physical Resource Block (PRB) within the LTE bandwidth for both uplink and downlink. It cannot use resources allocated for LTE’s Physical Downlink Control Channel (PDCCH) and Cell Specific Reference Signal (CRS). When NB-IoT is not active, its PRB can be used by LTE. It offers two sub-modes based on cell ID and antenna number: Same Physical Cell ID (PCI) and Different PCI.
- Guard-band mode: An LTE carrier can support an NB-IoT carrier in its guardbands if the LTE bandwidth is 5 MHz or more. This mode has minimal interference impact and does not reserve any PRB for NB-IoT.
- Stand-alone mode: Uses a new frequency carrier for NB-IoT, potentially replacing an existing GSM carrier. Its resource usage is similar to guard-band mode and does not affect the LTE network.
NB-IoT protocol features
Compared to regular LTE, NB-IoT uses fewer channels, signals, and transceivers. It also has simpler network protocols.
Main radio protocol features of NB-IoT
- Single HARQ Process: Utilizes a single Hybrid Automatic Repeat reQuest (HARQ) process for simplicity and efficiency.
- RLC AM Mode: Only uses Acknowledged Mode (AM) for the Radio Link Control (RLC) with simplified status reporting.
- Reduced Broadcast System Information: Limits the amount of system information broadcasted to reduce overhead and improve efficiency.
- Packet Data Convergence Protocol (PDCP) options:
- Option 1: Supports SRB 0 and 1 only, with no Access Stratum (AS) security (NAS security is used instead). The Packet Data Convergence Protocol (PDCP) operates in Transparent Mode (TM).
- Option 2: Includes SRB 0, 1, 2, and one Data Radio Bearer (DRB). Provides AS security, which is cached upon Radio Resource Control (RRC) connection release. Supports RRC connection suspend/resume procedures to maintain the AS security context.
Assembling the hardware: NB-IoT modules
Since NB-IoT is designed for low data rate applications and doesn’t need much memory, it’s also been streamlined in hardware which helps keep the cost of modules at the lower end.
If you’re developing your IoT device, here are some of the top NB-IoT radio modules currently available in the market.
- Nordic Semiconductor System-in-Package (SiP): nRF9160, nRF9161, nRF9151, nRF9131 mini
- Quectel: BC65, BC92, BC950K-GL, BC660K-GL, BC680-EU, BG95, BG96, BG95xA-GL, BG600L-M3, BG77, BG95-M3 Mini, BG96 Mini, BG77xA-GL
- SIMCom: SIM7022, Y7028
Getting ready for Narrowband IoT: NB-IoT SIMs
NB-IoT SIMs are available in different form factors. At Onomondo, we also offer them in pure software form — SoftSIM.
If you’re currently in R&D phase and testing NB-IoT, we offer a free trial to NB-IoT SIMs with access to various networks in Asia, Americas, and Europe.
Start testing Onomondo for free
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NB-IoT real-world use and applications
Just because NB-IoT is designed for IoT, doesn’t mean it fits every single use case. While NB-IoT is designed for low bandwidth applications, it may not be ideal for applications requiring higher data rates or more frequent data transmission.
What is NB-IoT used for? A practical guideline
Here is a summary of NB-IoT features and how it can affect your devices in the field.
| Aspect | NB-IoT specification | Practical implications |
|---|---|---|
| Bandwidth | Utilizes narrow bandwidth (200 kHz for stand alone deployment) | Wider coverage |
| Spectrum | Licensed | Helps minimize interference issues |
| Data rates | up to 250 kbps | Suitable for sending infrequent updates |
| Latency | 1.6 – 10 seconds (varies depending on application) | Fits delay-tolerant use cases |
| Max payload size | 1600 bytes (can vary depending on network architecture) | Not for high-data transmissions |
| Mobility | Limited handover support | Limited to static devices |
| Power class | Class 3 and 5 (Rel 13), 14 dBM (Rel 14) | Up to 10 years with 5 Watt Hour battery (depending on traffic and coverage needs) |
| Energy management | With power-saving features (PSM, eDRX) | Low to very low consumption |
| Coverage and penetration | Up to 164 dB Maximum Coupling Loss (MCL) | Works indoors and outdoors |
| Device complexity | Low complexity (only 1 transceiver for both sending and receiving data) | Lower cost (estimated module cost is approximately US$5) |
| Security | Standard LTE security with limitations on complex security algorithms | Implement security measures early on |
| Global deployment | Slower due to need for additional hardware | May not work everywhere |
| Roaming | Limited to no support | Not suitable for global deployments |
| SMS and VoLTE | Often not supported | Troubleshooting can be challenging |
NB-IoT’s diverse use cases
NB-IoT technology is appropriate for use cases that transmit low, infrequent, delay-tolerant data, with static or limited mobility. Here are some examples:
- Smart metering: Devices that send utility usage data infrequently (e.g. once a day) such as smart water meters.
- Environmental monitoring: Sensors that track weather conditions, air quality, or pollution levels and report data at set intervals.
- Smart cities: Infrastructure monitoring in urban areas, such as waste management.
- Industrial monitoring: Remote monitoring of industrial equipment and machinery for maintenance and performance data.
- Building automation: Also known as smart buildings, data transmissions about operational status and conditions such as lighting or HVAC are monitored and analyzed for efficiency.
- Health monitoring: Devices that track health metrics which report data infrequently and can tolerate some delay.
NB-IoT vs. other network technologies
Is LTE-M better than NB-IoT?
Just like NB-IoT, LTE-M is the other LPWAN technology largely based on LTE.
Both are meant for IoT applications, but LTE-M offers higher uplink and downlink speeds, and supports handover, SMS, and roaming.
This table below offers a quick overview of how NB-IoT directly compares with LTE.
LoRaWan vs NB-IoT in the field
Apart from LTE-M and NB-IoT, many go with LoRaWan (Long Range Wide Area Network) for cellular connectivity for their IoT devices. It’s open-source and low-cost making it ideal for low-power deployments that are on the smaller scale.
With limited technical support, concerns about security and reliability, and trouble with performing over-the-air updates due to low bandwidth, Intoto decided to go with LTE-M as they scale their environmental metering (live river data) solution.
→ Watch Scott Basgaard, CTO and Co-founder of Intoto, discuss his journey in scaling his smart metering solution, including transitioning from LoRaWan and NB-IoT.
NB-IoT 5G compatibility
While NB-IoT originated with LTE, it is designed to be forward-compatible with 5G networks.
NB-IoT can operate alongside 5G NR (New Radio) technologies, benefiting from the broader 5G ecosystem. The 3GPP has ensured that NB-IoT will continue to be supported in the 5G era, particularly for massive Machine Type Communications (mMTC), one of the three main use cases for 5G.
Is NB-IoT right for you?
NB-IoT is appropriate for use cases that transmit low, infrequent, delay-tolerant data, for static or limited-mobility devices.
Apart from the technology, other things such as market rollout, the cost of radio modules, the frequency of over-the-air updates, and your plans to scale affect NB-IoT’s suitability for your application.
However, before even deciding on a network technology for your IoT application, a practical first step is to find out what is actually offered in your deployment location.
See if NB-IoT is available in your target location with our free global coverage map.
Resources
- K.F. Muteba, K Djouani, T. Olwal. (2022). 5G NB-IoT: Design, Considerations, Solutions and Challenges. Procedia Computer Science. Vol. 198, pp. 86-93. https://doi.org/10.1016/j.procs.2021.12.214
- Kanj, Matthieu & Savaux, Vincent & Le Guen, Mathieu. (2020). A Tutorial on NB-IoT Physical Layer Design. IEEE Communications Surveys & Tutorials. PP. 10.1109/COMST.2020.3022751. https://ieeexplore.ieee.org/document/9194757
- Rastogi, E., Saxena, N., Roy, A., Shin, D.R. (2020)., Narrowband Internet of Things: A Comprehensive Study, Computer Networks, doi: https://doi.org/10.1016/j.comnet.2020.107209
- Y. Lin, F. Jiang, Z. Wang and Z. Wang. (2018). Research on PUF-Based Security Enhancement of Narrow-Band Internet of Things. IEEE 32nd International Conference on Advanced Information Networking and Applications (AINA), Krakow, Poland, pp. 702-709. 10.1109/AINA.2018.00106. https://ieeexplore.ieee.org/document/8432308
- GSMA. (2019). NB-IoT Deployment Guide to Basic Feature set Requirements. https://www.gsma.com/solutions-and-impact/technologies/internet-of-things/wp-content/uploads/2019/07/201906-GSMA-NB-IoT-Deployment-Guide-v3.pdf
