Read time 9 min
Behind the Signal: Tao Daniel
TeamBehind the signal
Quick answer: Most mobile consumer and medical wearables land on LTE-M, because it combines low power (PSM and eDRX), full handover between cells, VoLTE voice and a single antenna. NB-IoT fits wearables that stay largely in one place and send very little data, at the lowest module cost. LTE Cat 1bis gives about 10 Mbps over standard LTE with one antenna, and LTE Cat 4 is worth its higher power, size, cost and two-antenna design only when the device needs throughput nothing else can deliver, such as live HD video.
If your team is designing a connected wearable, choosing the cellular technology is one of the earliest and most consequential decisions you will make. The right choice gives the device the right balance of coverage, battery life, data throughput and hardware footprint. The wrong one leads to costly redesigns or a product that does not perform in the real world.
This article compares the four cellular technologies that come up most often in wearable development: NB-IoT, LTE-M, LTE Cat 1bis and LTE Cat 4. We look at each across the dimensions that matter when a device lives on someone's body, and give a concrete use case for each.
Which cellular technology fits which wearable?
| If your wearable… | Start with | Why |
|---|---|---|
| Stays largely stationary, sends small periodic packets and must run as long as possible on a small battery | NB-IoT | Lowest module cost, smallest footprint, one antenna, best deep indoor coverage |
| Moves with the user, needs voice (VoLTE) or interactive data and regular firmware updates | LTE-M | Full handover, low power, voice support, practical FOTA, one antenna |
| Needs larger data payloads or standard LTE coverage in regions where LTE-M availability is uncertain | LTE Cat 1bis | About 10 Mbps downlink, standard LTE roaming, strong FOTA, one antenna |
| Streams live HD video or handles large bidirectional data flows in real time | LTE Cat 4 | Up to 150 Mbps downlink, at the cost of power, size, module cost and two antennas |
What matters when choosing cellular connectivity for a wearable?
For wearables the trade-offs look different than they do for fixed industrial IoT or smartphone design, so it helps to name the evaluation criteria first.
- Network coverage. Wearables go wherever people go. The device has to stay connected in urban buildings, basements, rural areas and everywhere in between.
- Data rate. Some wearables only trickle small packets of sensor data, while others stream audio, video or large health datasets.
- Latency. For wearables with real-time feedback loops such as alarms, voice or interactive responses, how quickly data moves through the network matters as much as how much of it can move.
- Power consumption. Battery space is precious on any wearable. The cellular radio is frequently the dominant power draw, and the technology you choose sets the floor for battery life.
- Number of antennas. Every antenna needs physical space, a ground plane and clearance from the human body and other components. Fewer antennas mean a simpler integration problem.
- Radio module size. The cellular module takes PCB area that a wearable does not have in abundance. A smaller module gives more design flexibility.
- Module cost. At scale, the cellular module is often the highest-cost component on the BOM, and the right technology for the job is rarely the most expensive one.
- FOTA capability. Firmware-over-the-air updates are a requirement for any device in the field. How well a technology handles large firmware downloads reliably, efficiently and without draining the battery is a real-world constraint that teams often underestimate early in development.
NB-IoT for wearables: lean, long-lived and location-limited
NB-IoT (Narrowband IoT) was designed to keep devices connected and alive for years while sending very little data. It operates within existing LTE spectrum in a 180 kHz channel, which is how it achieves its deep indoor and rural penetration: up to 20 dB of additional link budget compared with standard LTE, the best coverage of the four technologies compared here.
| Dimension | NB-IoT |
|---|---|
| Network coverage | Excellent: best deep indoor and rural penetration |
| Data rate | ~26 kbps DL / 62 kbps UL |
| Latency | High: suited to infrequent, non-time-critical messages |
| Power consumption | Extremely low: PSM and eDRX enable years on a small battery |
| Number of antennas | 1 |
| Radio module size | Very small |
| Module cost | Lowest of the four |
| FOTA capability | Limited: low throughput makes large firmware updates slow and battery-intensive |
Mobility and firmware updates on NB-IoT
NB-IoT was not designed for mobility. Depending on the network, handover between cells is either limited or not supported. If the device stays largely stationary, or moves slowly within a stable coverage area, this is not a problem; if it moves quickly through multiple cells, NB-IoT will struggle.
FOTA is also difficult on NB-IoT. Low throughput means large firmware images take a long time to transfer, and that transfer time costs battery. For devices with simple, infrequently updated firmware this is manageable, but for a more complex or frequently updated software stack it becomes a real operational burden.
Use case: continuous health monitoring patch
A disposable biometric patch is worn for multi-day monitoring in a hospital or home care setting. It sends heart rate, temperature and activity data in small periodic bursts and never leaves a defined area. Battery life is the primary constraint, data volumes are minimal, and firmware updates are small and infrequent.
NB-IoT is a natural fit here: the lowest module cost, the smallest footprint, a single antenna and years of theoretical battery life. Deep indoor penetration keeps the patch reporting from inside a building where an LTE signal would be marginal.
LTE-M for wearables: the sweet spot for mobile devices
LTE-M (also called Cat-M1) is where most modern consumer and medical wearables land. It keeps much of NB-IoT's power efficiency while adding real mobility support, higher data rates, lower latency and voice through VoLTE. LTE-M operates in a 1.4 MHz channel within LTE bands and inherits the network's full handover mechanism, so the connection follows the user as they move.
| Dimension | LTE-M |
|---|---|
| Network coverage | Good: enhanced coverage mode, broadly deployed globally |
| Data rate | ~1 Mbps DL / 1 Mbps UL |
| Latency | Low to moderate: tens of milliseconds, suitable for interactive IoT |
| Power consumption | Low: PSM and eDRX supported |
| Number of antennas | 1 (single antenna mandatory in the specification) |
| Radio module size | Small |
| Module cost | Low: multi-mode NB-IoT + LTE-M modules are common and economical |
| FOTA capability | Good: throughput and latency make periodic firmware updates practical |
LTE-M typically has around 3 to 6 dB less link budget than NB-IoT, so it does not penetrate quite as deep into challenging environments. In most real deployments this is not a limiting factor, but verify it with your target operators and geographies before committing. For more on the technology itself, see our article on the benefits of LTE-M for IoT.
Use case: connected smartwatch with emergency calling
A smartwatch tracks activity, streams heart rate data to a health platform and supports VoLTE calls to emergency services or a caregiver. The user moves continuously through offices, transport networks and outdoor areas.
LTE-M hands over between cells without dropping the connection, supports voice without an additional radio and manages firmware updates efficiently in the background. It does all of this with a single antenna and a power envelope that keeps a realistic battery viable. For this kind of product LTE-M consistently outperforms both the simpler option (NB-IoT lacks mobility and voice) and the more capable one (Cat 4 demands too much power and PCB space).
[ENGINEER INPUT (optional, adds first-hand proof): One or two sentences on an LTE-M wearable or small-device project Radientum has worked on, for example what the antenna had to achieve. Link the LTE Cat-M1 antenna case study here if it fits.]
LTE Cat 1bis for wearables: mid-range data with a single antenna
LTE Cat 1bis is a relatively recent addition to the cellular landscape, introduced as a deliberate simplification of LTE Cat 1. The key difference is that Cat 1bis is specified with a single antenna instead of the two required for Cat 1's 2x2 MIMO. That change substantially reduces antenna integration complexity, which matters a great deal in a compact wearable.
| Dimension | LTE Cat 1bis |
|---|---|
| Network coverage | Standard LTE: available wherever LTE is deployed |
| Data rate | ~10 Mbps DL / 5 Mbps UL |
| Latency | Low: standard LTE latency |
| Power consumption | Moderate |
| Number of antennas | 1 |
| Radio module size | Medium-small |
| Module cost | Moderate: higher than LTE-M, lower than Cat 4 |
| FOTA capability | Strong: higher throughput makes large firmware images fast and efficient |
Cat 1bis fills a useful gap: substantially more throughput than LTE-M without the two-antenna configuration Cat 4 demands. Its standard LTE foundation also brings strong roaming support and mature FOTA infrastructure globally, which helps devices that ship to multiple regions or need frequent firmware updates. If your use case involves larger data payloads, more interactive data flows or deployment where LTE-M coverage is inconsistent, Cat 1bis gives you standard LTE reliability with a simpler antenna setup.
Use case: connected personal safety device
A wearable GPS tracker for lone workers in field environments reports precise location frequently, sends environmental sensor data and has to work over standard LTE wherever the worker is deployed, including regions where LTE-M availability cannot be guaranteed. It also needs reliable periodic firmware updates in the field.
Cat 1bis delivers the coverage consistency, the data rate for responsive location services and the FOTA capability to manage updates efficiently, all through a single antenna. Power consumption is higher than with LTE-M, but this device has a larger form factor and charging infrastructure available, so the trade-off is acceptable.
LTE Cat 4 for wearables: high throughput when the data demands it
LTE Cat 4 is the highest-capability option in this comparison, delivering up to 150 Mbps downlink and 50 Mbps uplink through 2x2 MIMO. That performance has real costs: higher power consumption, a larger module, the highest BOM cost of the four, and two antennas with the integration complexity that brings. In a wearable, these constraints need to be justified by a genuine data rate requirement.
| Dimension | LTE Cat 4 |
|---|---|
| Network coverage | Standard LTE: worst deep-indoor performance of the four |
| Data rate | ~150 Mbps DL / 50 Mbps UL |
| Latency | Low: full LTE performance |
| Power consumption | High: not optimised for battery-constrained devices |
| Number of antennas | 2 (2x2 MIMO) |
| Radio module size | Larger |
| Module cost | Highest of the four |
| FOTA capability | Excellent: high throughput and low latency make large updates fast |
Treat Cat 4 as the choice for when nothing else can deliver the throughput you need. If your wearable streams continuous high-resolution video or handles large bidirectional data flows in real time, this is where you end up. For anything less demanding, the power, size and cost penalty is difficult to justify.
Use case: body-worn camera for healthcare or security
A clinician or security officer wears a camera system that streams live HD video to a monitoring platform and receives real-time audio and instructions in return. The data rate requirement is fixed: anything lower compresses quality to the point of defeating the product's purpose.
The device sits in a harness with meaningful physical volume and is charged between shifts. Cat 4's power and size trade-offs are acceptable in this form factor precisely because the throughput requirement cannot be met any other way, and its FOTA capability is a bonus, since large system images update quickly and reliably.
NB-IoT vs LTE-M vs LTE Cat 1bis vs LTE Cat 4: summary comparison
| NB-IoT | LTE-M | LTE Cat 1bis | LTE Cat 4 | |
|---|---|---|---|---|
| Network coverage | ★★★★★ | ★★★★☆ | ★★★☆☆ | ★★★☆☆ |
| Data rate | ~26 kbps | ~1 Mbps | ~10 Mbps | ~150 Mbps |
| Latency | High | Low to moderate | Low | Low |
| Power consumption | Extremely low | Low | Moderate | High |
| Antennas required | 1 | 1 | 1 | 2 |
| Module size | Very small | Small | Medium-small | Larger |
| Module cost | Lowest | Low | Moderate | Highest |
| FOTA capability | Limited | Good | Strong | Excellent |
| Mobility support | Limited | Full | Full | Full |
Check operator support before you commit
Mobile network operators have deployed NB-IoT and LTE-M broadly around the world, and many support both on the same physical LTE network. Coverage, roaming agreements and network configuration still vary meaningfully by region and operator. LTE Cat 1bis and Cat 4 are available wherever standard LTE is deployed, which gives them an advantage in regions where LTE-M rollout is still maturing.
Before finalising your technology choice, validate your target operators' support and roaming coverage in every region where the device will operate. A coverage gap found at the integration stage is a much more expensive problem than one found during technology selection.
Why the antenna decides whether your cellular choice works
Choosing the cellular standard narrows the design space considerably, but it does not close it. Once you have committed to a technology, the antenna integration work begins in earnest.
Wearables create conditions that a generic antenna approach handles poorly. The human body absorbs RF energy, detuning the antenna and reducing efficiency in ways that benchtop testing will not reveal. Space is so tight that standard antenna formats rarely fit without modification, and the two-antenna configuration of Cat 4 needs careful placement and isolation work. Regulatory compliance, SAR limits in particular, adds another layer of constraint that feeds directly back into antenna design decisions.
To go deeper on cellular antenna design for IoT and connected devices, our cellular antenna design page covers the technical fundamentals, integration considerations and common failure modes. For how antenna design changes when the device is worn on the body, including body proximity effects, form factor constraints, regulatory requirements and the testing that validates it all, see our antenna design for wearables page.
Choosing the right technology is the start. Getting the antenna right is what determines whether the device actually works, and if you want our antenna engineers to look at your wearable early, contact Radientum.
