NOMA-Based LPWA Networks

Abstract

Non-orthogonal multiple access (NOMA) is used in the uplink for LPWAN for providing services to users or nodes requiring a different set of services. The LoRa nodes usually suffer from inter-cluster and intra-cluster interference. In this article, both are minimized by assigning spreading factor (SF) depending upon their channel coefficient. The assignment of different SF and use of NOMA allows successive interference cancellation (SIC) which itself reduces interference while decoding the signals. In numerical results, several LoRa nodes are varied to calculate the number of packets transmitted, percentage collisions, and throughput, which shows that the use of NOMA enhances the performance considerably. The proposed algorithm allocates channels to LoRa nodes based on their channel gains and distance which reduces collisions and increases throughput.