Non-terrestrial networks have moved from early exploration to a more structured and capable part of the 3GPP ecosystem in a relatively short span of time. A recent presentation by Sertaç Kaya at the Global 5G Evolution webinar (embedded below) provided a useful walkthrough of how NTN specifications have evolved since Release 17, highlighting both incremental improvements and some more fundamental shifts.
Release 17 marked the starting point for NTN within 3GPP. The focus at this stage was understandably narrow, laying down the baseline architecture and assumptions. Only transparent payloads were considered, meaning satellites acted largely as relays rather than performing any onboard processing. The spectrum options were limited, confined to L-band and S-band in FR1, and bandwidth was modest. The system design also assumed that user equipment would be equipped with GNSS capabilities, which played a key role in handling challenges such as Doppler shift and long round trip delays.
Even at this early stage, some important NTN-specific adaptations were introduced. These included mechanisms to compensate for propagation delays, as well as new signalling elements to support satellite access. Mobility management also began to take shape, with the introduction of conditional handovers based on time and location, reflecting the dynamic nature of satellite coverage.
Release 18 built on this foundation and can be seen as a phase of practical enhancement. One of the key developments was the expansion of available spectrum, including the introduction of Ka-band and increased bandwidth options. This was important for improving capacity and enabling more demanding use cases.
Another notable shift was the introduction of architectural flexibility, including the possibility of placing user plane functions on satellites. This effectively brings edge computing into the NTN domain and helps reduce latency for certain applications. At the same time, there were improvements in mobility, with better coordination between terrestrial and non-terrestrial networks. Systems were enhanced to provide information about neighbouring cells across both domains, making transitions more seamless.
Energy efficiency also received attention, particularly for scenarios with intermittent coverage. Mechanisms were introduced to prevent devices from attempting network access when no coverage was available, helping to conserve battery life. Enhancements to uplink coverage and the introduction of network-based location verification further strengthened the system.
Release 19 represents a more significant step forward and, in many ways, changes the character of NTN within 3GPP. The most important development is the support for regenerative payloads. This effectively turns satellites into base stations in space, capable of processing signals rather than simply forwarding them. This shift enables new capabilities such as direct communication between user devices via satellite and more advanced routing options.
With regenerative payloads comes the possibility of store and forward operation. This is particularly relevant for IoT scenarios where continuous connectivity is not guaranteed. Data can be transmitted to a satellite, stored onboard, and then forwarded to the ground network when a feeder link becomes available. This model is well suited to delay tolerant applications and expands the practical reach of NTN services.
Release 19 also relaxes some of the earlier assumptions about user equipment. GNSS capability is no longer mandatory, which broadens the range of devices that can be supported. At the same time, there are enhancements in coverage and capacity, along with support for additional frequency bands and wider bandwidths. Power classes have been expanded, and support for reduced capability devices has been introduced, aligning NTN more closely with the broader 5G device ecosystem.
Mobility and service continuity continue to evolve as well. Improvements in signalling and system information help devices manage transitions between satellites and between NTN and terrestrial networks. There is also increasing support for broadcasting and IoT-specific features, reflecting the growing diversity of use cases.
Looking ahead, the work planned for Release 20 suggests a continued focus on making NTN more robust and user friendly. Areas under study include support for voice services over satellite, improved location capabilities for emergency services, and enhanced broadcast mechanisms. There is also interest in multi-orbit operation, which could allow networks to make better use of different satellite constellations depending on service requirements.
Taken together, these developments show how NTN is steadily maturing within the 3GPP framework. What started as a limited extension of terrestrial networks is evolving into a more integrated and capable system, with the potential to support a wide range of services from broadband connectivity to IoT and emergency communications.
Related Posts:
- Free 6G Training: Toward Native NTN Integration in 6G
- Connectivity Technology Blog: Skylo’s Work on Making NB-NTN Voice a Reality
- The 3G4G Blog - 5G-Advanced Store and Forward (S&F): Enabling Resilient IoT Communications via Satellite
- The 3G4G Blog: Tutorial Session on Non-Terrestrial Networks (NTNs) and 3GPP Standards from 5G to 6G
- Connectivity Technology Blog: Tutorial Session on Current Trends and Key Challenges of Satellite communications
- Connectivity Technology Blog: Will 5G NTN Deliver on the Promised Use Cases?
Comments
Post a Comment