Symmetry Chirp Spread Spectrum Modulation Used in LEO Satellite Internet of Things

With the development of Internet of Things (IoT), the world gradually moves toward the interconnection of all things. In terrestrial networks, narrowband-IoT and Long Rage (LoRa) are used widely in the IoT industry. For low-earth-orbit (LEO) satellites, they have a lot of conspicuous advantages, such as broader coverage and lower construction cost. In this letter, we place emphasis on the application of LoRa-related technologies to LEO satellite communication systems, and the modulation is the prior research. Chirp spread spectrum (CSS) modulation is the most important technology in LoRa. Therefore, the research of CSS modulation used in the satellite IoT is imperative.