An NB-IoT payload for space communications and navigation

Abstract

This paper presents a payload design for a Narrowband Internet of Things (NB-IoT) based communication and navigational system. The main objective of this design is to enable the integration of NB-IoT in a constellation of satellites. NB-IoT technology is attracting considerable attention in satellite communications because it has the potential to support reliable, wide-area, and low-power connectivity for critical applications such as telemetry, command and control, and safety messaging. Its versatility makes NB-IoT particularly well-suited to both conventional aviation and the expanding Unmanned Aerial Vehicle (UAV) sector. Drawing on these use cases, this paper identifies the key requirements and uses them to inform the payload design. The payload leverages Software-Defined Radio (SDR) technology for operational flexibility, addressing spectrum allocation, RF interference, and Doppler shift challenges. The design uses a phased-array antenna design of 10 by 10 circular patch elements optimised for space-based NB-IoT transmissions in the S-band frequency. This allows for electronic steering of its beam, minimising the overall payload mass and complexity while increasing its footprint and ensuring connectivity within a 40-degree half-cone angle. Navigation signal processing is achieved by leveraging the Doppler shifting of the communication signal, providing a velocity-based location. To provide a reliable communications link, the system also incorporates error correction techniques in a protocol designed and implemented to compensate for the Doppler shift in the signal. To validate the results of the design, a technology demonstrator using an SDR as well as custom Electrical Power System (EPS) and On-Board Data Handling (OBDH) boards are presented. These results demonstrate that successful connectivity and data transmission are feasible in a simulated environment, paving the way for future satellite-to-UAV communication using NB-IoT protocols. This payload system will contribute to the advancement of satellite-based NB-IoT networks, offering new possibilities for autonomous aerial operations. Future work could focus on optimising power efficiency and conducting real-world flight tests to validate system performance and reliability further.