Engineering Considerations for Integrating NTN into IoT Devices

Terrestrial cellular networks provide effective coverage in many regions, but their reach remains uneven in remote or sparsely populated areas. This results in blind spots for IoT applications that extend into maritime routes, forests, or large stretches of agricultural land. Non-terrestrial networks (NTNs), which extend cellular IoT connectivity to satellites, provide a way to fill these gaps.

This article discusses the engineering considerations for integrating NTN capabilities into IoT devices, covering the trade-offs of remote reporting, fallback connectivity, and continuous satellite use. It also examines the technical challenges related to network access, antennas, and power management, and considers how Nordic Semiconductor’s nRF9151 module provides a pathway for engineers to implement hybrid NTN and terrestrial solutions.

What Are the Core Engineering Challenges in Hybrid NTN + Terrestrial Devices?

Designing devices that rely exclusively on terrestrial networks or exclusively on NTNs is straightforward. For instance, a terrestrial-only device operates within the familiar LTE-M or NB-IoT frameworks where the challenges primarily relate to coverage limitations and spectrum availability. Similarly, a device intended only for NTN connectivity can be designed around fixed parameters such as satellite frequency bands, latency expectations, and power requirements. In both cases, the system is optimized for a single connectivity environment, and the hardware and firmware can be streamlined to support that environment alone.

The challenge arises when a device is expected to operate smoothly across both terrestrial and NTNs. Hybrid devices are expected to maintain connectivity in a wide range of conditions, moving fluidly between ground-based and satellite infrastructure without manual intervention. This dual requirement creates added layers of complexity in both design and operation. Hybrid designs accommodate variation in latency, signal strength, and handover behavior as the device transitions between networks.

In this regard, the process of switching between terrestrial and satellite networks is the key challenge. Relying too heavily on terrestrial networks can result in connectivity gaps when coverage is unavailable, but defaulting to satellite connectivity too readily can drain batteries and increase costs unnecessarily. Therefore, firmware should be designed to evaluate network conditions in real time, weighing parameters such as signal quality, location, and data transmission requirements before initiating a switch.

Hybrid devices also face the challenge of maintaining consistency from the perspective of the application or cloud service they connect to. Ideally, the device should continue to deliver data reliably and in a format that does not disrupt backend systems, while the underlying network may change. Achieving this continuity adds to the engineering considerations, since switching networks may involve differences in latency, data throughput, and availability. 

Application Scenarios

Remote Reporting

The simplest entry point for integrating NTNs into IoT devices is in remote reporting applications. These are typically low-complexity systems that transmit small amounts of data at long intervals and are suited for the limited bandwidth and higher latency associated with satellite links. Weather stations, forestry sensors, dam monitoring systems, and power line inspection devices fall into this category. As these devices are usually installed in locations where maintenance is infrequent, they can be fitted with larger enclosures and battery packs that offset the higher power needs of satellite communication. This design flexibility allows engineers to prioritize reliability over form factor, ensuring continued delivery of essential data such as temperature, rainfall, or structural strain measurements in areas without terrestrial coverage.

An extension of this approach is asset tracking in industries such as transportation and logistics. Devices that record and transmit position data only once every few hours present a manageable challenge as they do not require real-time location updates, so a system can conserve energy by connecting opportunistically to satellites when needed.

NTN as a Fallback to Terrestrial

Another use case involves devices that primarily rely on terrestrial networks but retain NTN access as a secondary option when ground-based infrastructure is unavailable. This fallback model is common in position tracking and sensor applications that deliver consistent reporting but do not transmit large volumes of data. Devices in this category typically send small payloads at extended intervals. The engineering challenge lies in determining the right conditions under which to switch from terrestrial to satellite connectivity.

If a device spends excessive time searching for a weak or unavailable terrestrial signal, it risks draining its battery without successfully transmitting data. Strategies such as implementing geofences can help avoid this problem by instructing devices to rely on NTNs only when they are known to be in regions where terrestrial coverage is absent, such as open oceans or sparsely populated landscapes. Another approach is to configure the device firmware to evaluate connection quality and select the most reliable mode automatically. However, this adds to development complexity and often requires close collaboration with module manufacturers to optimize firmware behavior.

Engineers must also weigh the trade-offs between persisting with a degraded terrestrial signal and switching to an NTN. As terrestrial networks weaken, devices tend to reduce bandwidth and adopt more robust modulation schemes, which prolongs connectivity but at the cost of efficiency. Deciding when it is better to abandon a weak terrestrial link in favor of satellite connectivity requires consideration of both energy consumption and data reliability.

Continuous NTN Connectivity

The most demanding application scenario is continuous reliance on satellite networks. Devices that need to maintain an uninterrupted link to an NTN face several engineering constraints. For instance, maintaining a satellite connection over extended periods requires more frequent transmission cycles and longer active times, which can consume more power and quickly deplete batteries in compact devices.

Data cost can also become more significant in continuous NTN connectivity. Transmitting large amounts of data can substantially increase operating costs, since bandwidth on satellite networks is limited and expensive relative to terrestrial infrastructure. This usually forces developers to design systems that compress data, prioritize critical information, or otherwise limit the volume of transmitted packets.

Timing is also a technical consideration. For example, acquiring a GPS lock from a cold start can take up to 35-45 seconds, which complicates synchronization with satellite constellations. Suppose the device cannot reliably predict when a satellite will be overhead. In that case, this delay can lead to missed transmission opportunities or require additional active time that further drains the battery. Moreover, satellite constellations themselves have finite capacity, and engineers must account for potential congestion when many devices attempt to access the same link simultaneously. These limitations show that careful planning when designing IoT systems that depend exclusively on NTNs for their operation is imperative.

Technical Considerations for NTN Integration

Although hybrid NTN modules simplify some aspects of hardware integration, engineers still need to account for network access, frequency band compatibility, antenna performance, and the balance between data costs and power efficiency. Addressing these considerations early in the design process ensures that devices are reliable and adaptable in diverse deployment environments.

Network Access

Accessing NTN services is not just a matter of hardware capability, but it also depends on the agreements between satellite operators and terrestrial network providers. Most NTN connectivity today is made available through roaming partnerships with mobile network operators (MNOs) or mobile virtual network operators (MVNOs). This arrangement enables devices to connect to NTNs similarly to how they roam between terrestrial networks, provided the SIM in use is provisioned with the appropriate roaming agreements.

This creates an additional planning step for the developers. The choice of MNO or MVNO influences which satellite constellations are accessible, and coverage can vary depending on the region. Therefore, the devices must be designed with roaming-enabled SIMs and flexible network stacks that can accommodate multiple potential providers. Since roaming is not always uniformly supported across markets, engineers may need to consider regional deployment strategies, selecting connectivity partners that align with the expected operating environments of their devices.

Frequency Bands and Antennas

NTNs typically operate in the L-band, around 1.3 GHz, or the S-band, around 2 GHz. These frequencies are chosen because they balance propagation characteristics with manageable antenna dimensions, which makes them suitable for compact IoT devices. As both geostationary and low Earth orbit constellations rely on the same general frequency ranges, this allows designers to use a single antenna configuration to support both modes. This consistency reduces hardware complexity, but does not eliminate the need for careful optimization.

Antenna design directly affects link quality and device efficiency. Solutions such as dual-mode antennas can simplify integration by enabling both terrestrial and satellite connectivity within a single package. For example, commercially available dual-mode antennas, including TE Connectivity’s D2D series, demonstrate how antenna technology can be engineered to handle this dual requirement. However, there are still trade-offs between form factor, efficiency, and reliability.

Compact, embedded antennas can be sufficient for devices that only occasionally fall back on NTN links, where satellite communication is used as a backup rather than the primary channel. However, when devices are expected to rely heavily on satellite connectivity, dedicated external antennas generally provide stronger performance. The larger physical size of external antennas improves gain and link robustness, which can be critical when dealing with weaker satellite signals or challenging environmental conditions. Choosing between embedded and dedicated antennas ultimately comes down to expected usage patterns, available device space, and the acceptable balance between size and efficiency.

Power and Data Management

Power consumption and data management are recurring challenges in NTN-enabled designs. Satellite communication involves longer transmission distances and, in some cases, longer connection establishment times than terrestrial networks. These factors increase the energy required to transmit data, which can significantly affect the lifespan of battery-powered devices. For IoT applications intended to operate in the field for years without maintenance, overlooking power optimization strategies can compromise deployment viability.

Another factor is the higher cost per kilobyte of data transmitted over NTNs compared to terrestrial networks. Devices should be designed to minimize payload size, prioritize essential transmissions, and schedule communication intervals that balance responsiveness with energy efficiency. For instance, batching non-urgent data into periodic transmissions can reduce the overhead of repeated link establishment, and adaptive reporting intervals allow devices to adjust transmission frequency based on the urgency of the data.

Nordic’s Role: The nRF9151 as a Multi-Protocol Platform

Nordic Semiconductor’s nRF9151 module is a practical, integrated solution for hybrid terrestrial and NTN connectivity. It supports multiple protocols, including LTE-M, NB-IoT, and NB-NTN, along with GNSS for positioning, all within a single compact system-in-package (SiP).

The nRF9151’s architecture centers around an Arm Cortex-M33 processor with 1 MB of flash and 256 KB of RAM, enabling in-device application processing and flexibility. It supports LTE bands from 700 MHz to 2200 MHz and DECT NR+ bands around 1.9 GHz, covering a broad spectrum suitable for both terrestrial and NTN communications.

This multi-mode capability simplifies device design and reduces complexity by providing a unified hardware and firmware platform capable of dynamically switching between terrestrial and satellite connectivity. Its power class options allow balancing transmission power and battery life according to specific deployment environments. Moreover, from a lifecycle perspective, the nRF9151 provides a foundation for devices that are expected to remain operational for many years.

Nordic brings an established developer ecosystem to NTN adoption. Nordic’s ecosystem, including their SDKs, developer tools, and support services, further lowers the barriers for engineers to adopt NTN-enabled IoT solutions. The same tools, software development kits, and cloud integration frameworks that engineers already use for cellular IoT projects extend to NTN-capable solutions. This continuity reduces the learning curve and lowers the barriers to implementing hybrid devices.

Conclusion: Designing for Future-Ready IoT Connectivity

Integrating NTN into IoT devices introduces a spectrum of engineering trade-offs involving power consumption, network switching logic, antenna design, and data cost considerations. Hybrid devices that combine terrestrial and non-terrestrial connectivity extend IoT reach globally, particularly benefiting applications in remote, rural, or critical environments.

NTNs are crucial global IoT deployments; however, their success requires carefully designing switching strategies, hardware components, and power management. A multi-protocol module like the Nordic NRF9151 provides a convenient way for engineers to design devices that operate in both terrestrial and non-terrestrial networks.

References

1. Nordic Semiconductor [Online]. Mouser Electronics. Available at: https://eu.mouser.com/manufacturer/nordic-semiconductor/ (Accessed on September 25, 2025)

2. Nordic Semiconductor nRF9151 Low-Power System-in-Package (SiP) [Online]. Mouser Electronics. Available at: https://eu.mouser.com/new/nordic-semiconductor/nordic-semi-nrf9151-sip/ (Accessed on September 25, 2025)

3. TE Connectivity D2D Dual Mode Antennas [Online]. Mouser Electronics. Available at: https://eu.mouser.com/new/te-connectivity/te-connectivity-d2d-antennas/ (Accessed on September 25, 2025)