Design & Implementation of an Adaptive Data Rate LoRa Modem f. LEO Satellites Using SDR & GNU Radio

Gizem Ari Özcan takes us to space with her presentation, a joint effort with Ceren Gülsüm Karaköse and Dr. Dr. Meltem Köroglu

Low Earth Orbit (LEO) satellite networks are pivotal for global communications, particularly in remote and underserved areas. The Long Range (LoRa) communication protocol, primarily utilized in IoT satellite networks due to its low power consumption and long-range capabilities, emerges as an ideal candidate for enhancing LEO communications. This study presents the development of an adaptive data rate LoRa modem specifically tailored for LEO satellite applications, leveraging Software Defined Radio (SDR) and GNU Radio. This approach not only fosters flexibility and scalability in communications technology but also significantly reduces development costs compared to traditional hardware implementations. We detail the design process of the LoRa modem, emphasizing the integration of an adaptive data rate mechanism that optimizes communication in the dynamically changing satellite environment. A crucial feature of our system is adaptively measuring the Signal-to-Noise Ratio (SNR) at the receiver sides and determining the LoRa parameters for the next transmission based on the link budget and LoRa receiver sensitivity values for different Spreading Factors (SF) and Bandwidth (BW) values. Key to our methodology is the simulation of the satellite channel, incorporating realistic effects such as Doppler shifts and path losses computed through the SGP4 orbit propagator. This simulation ensures that our modem design can withstand the unique challenges posed by LEO satellite operations. The results indicate promising improvements in bandwidth efficiency and reliability, making a strong case for the adoption of LoRa in future LEO satellite communication systems. This research paves the way for cost-effective, robust satellite communications, enhancing connectivity in an increasingly data-driven world.

This talk took place on 2024-08-30 at GSI/FAIR Darmstadt, as part of the European GNU Radio days 2024.Full talk details (including slides) are available at:https://events.gnuradio.org/event/23/...