A novel orthogonal LoRa multiple access algorithm for satellite Internet of Things

In recent years, LoRa has been extensively researched in the satellite Internet of Things (IoT). However, the multiple access technology of LoRa is still one of the bottlenecks of satellite IoT. To improve the multiple access performance of LoRa satellite IoT, based on the orthogonality of LoRa symbols in the fractional domain, this paper proposes a low complexity Orthogonal LoRa Multiple Access (OLMA) algorithm for multiple LoRa users occupying the same frequency bandwidth. The algorithm introduces the address code to divide the fractional bandwidth into multiple parts, and the OLMA users with different address codes occupy different parts to transmit the information code, thus avoiding mutual interference caused by collisions in the same frequency bandwidth. The multiple access capability of OLMA can be flexibly configured only by simply adjusting the length of the address code according to the actual application requirements of data transmission. Theoretical analysis and simulation results show that the OLMA algorithm can greatly improve the multiple access capability and the total transmission bit rate of LoRa IoT without changing the existing LoRa modulation parameters and process.