5G NTN testbed for RedCap Direct-to-Satellite communication

The advent of 5G Non-Terrestrial Networks (NTNs) and low Earth orbit (LEO) satellites communication domain by making connectivity services accessible to human and machine-user equipment (UE), thus enabling unprecedented global connectivity. Introduced in 3GPP’s Release 17, 5G NTN with non-regenerative payload acts as a relay node, where base stations in the terrestrial network (TN) facilitate and manage seamless connections between UE and satellites.
The target of our study is to design and instrument the end-to-end 5G NTN testbed setup for IoT application with a focus on new radio (NR) Reduced Capability (RedCap) technology. The previously introduced IoT technologies (i.e. LTE-MTC/NB-IoT) lack support for specific target industries that need small IoT UE form factor, low development costs, and high battery life., RedCap is an ideal middle ground, offering a balanced solution with reduced complexity and cost. The main components of the planned testbed include (i) the UE incorporating NR RedCap features, (ii) the channel emulator to emulate satellite communication channel characteristics, and (iii) an OpenAirInterface (OAI) Box implementing the gNodeB and core network components. The testbed is designed to evaluate RedCap UE performance in direct-to-satellite communication scenarios, enabling precise assessments of RedCap NTN performance.
The further development of the testbed will enable emulating and validating coexistence between TN-NTN, e.g., by testing and verifying handover protocols across these domains. This controlled environment thus provides a complete end-to-end platform for analyzing network interoperability, handover efficiency, and UE adaptability in NTN contexts, supporting the development of reliable satellite communication capabilities within the 3GPP framework.