Concurrent Transmission and Multiuser Detection of LoRa Signals

This article investigates a new model to improve the scalability of low-power long-range (LoRa) networks by allowing group multiple end devices (EDs) communicate with multi-antenna gateways simultaneously (i.e., in same time slot) on frequency band and using spreading factor. The maximum-likelihood (ML) decision rule is first derived for noncoherent detection information bits transmitted group. To overcome high complexity ML detection, we propose suboptimal two-stage algorithm balance computational error performance. In stage, identify chirps (without knowing which EDs transmit them). second determine that specific identified from stage. performance also optimize powers minimize similarity, measured Jaccard coefficient, between received any pair As power control optimization problem nonconvex, use concepts successive convex approximation transform it an approximate can be solved iteratively guaranteed reach solution. Simulation results demonstrate justify tradeoff penalties network proposed LoRa model. particular, grouping two or three each concurrent transmission, uplink capacity doubled tripled over conventional network, albeit at expense additional 3.0 4.7 dB power.