On the Header Detection in LoRaWAN LR-FHSS

This paper proposes a novel header detection scheme for Long-Range Frequency Hopping Spread Spectrum (LR-FHSS) for Direct to Satellite Internet of Things (DtS-IoT). The main focus is on developing a general structure capable of addressing transmission challenges in Low Earth Orbit (LEO) environments, such as Doppler shift and Doppler rate effects, while maintaining limited computational complexity. Our proposed implementation is completely compliant with the LR-FHSS standard, whereas the existing literature considers implementations that are not fully compliant, making the evaluation and comparison of results difficult. Our simulations demonstrate that the proposed system achieves valuable performance (e.g., it can sustain a Doppler rate up to 250 Hz/s) while requiring a DFT size more than 10 times lower than a reference implementation available in literature. The analysis is centered on the operational requirements in the EU region.