On the Effect of Multi-Packet Reception on Redundant Gateways in LoRAWANs

In this paper, the impact of redundant packet reception at multiple gateways on data reliability is studied under the LoRaWAN architecture. Given a successful transmission could be the result of either a first attempt after a data packet's generation, or a retry after several transmission failures, the Average Successful Transmission Probability (ASTP) is introduced to qualify LoRaWAN's reliability performance. To calculate the probability of a successful reception without retransmission, we consider all the possible causes for a packet collision. The number of potential interferers, which is vital for the collision analyses and directly determined by the relative locations of the relevant multiple gateways, is determined by geometric arguments. Similarly, the probability for achieving a successful retransmission is also obtained. Finally, ASTP is rigorously modeled as a function of end device density, gateway density, and traffic intensity. The analytical results have been verified by extensive simulation experiments. We believe that the analytical model can provide useful insights into the scalability of LoRaWANs and provide guidelines for their deployments.