Analysis of Superimposed LoRa in Multi-User Networks

The emergence of Internet-of-Things (IoT) has enabled the connectivity of billions of smart devices and sensor nodes to the Internet. Such a large number of connected devices requires the development of new energy efficient and long-range technologies for the successful realization of IoT applications. Within this context, long range (LoRa) has emerged as one of the prominent low power wide area network (LPWAN) technologies that is envisioned to accommodate the future IoT requirements. Nevertheless, in dense deployments, LoRa has limited capacity since it adopts the ALOHA random access protocol which suffers from unavoidable collisions. Therefore, recently, non-orthogonal multiple access (NOMA) has been integrated with LoRa in order to improve its spectral efficiency by multiplexing users in the power domain. This work studies the performance of NOMA-enabled LoRa networks in both AWGN and Rayleigh fading channels. Finally, the effect of inter-spreading factor interference is investigated in order to highlight on the impact of the imperfect orthogonality of LoRa spreading factors.