Exploiting Time Diversity of LoRa Networks Through Optimum Message Replication

LoRA networks have been gaining momentum as an accessible and open solution for massive connectivity in the Internet-of- Things. Besides the popularity, however, academic research has shown that the technology has limitations. In particular to the connectivity argument, it became clear that massive coverage comes at the price of severely reduced duty cycles, and the increased number of users in the network significantly elevates packet loss due to collisions. In this paper, we exploit time diversity to increase the probability of successful packet delivery in LoRA uplink. We build on previous work to model the outage and coverage probabilities of LoRA channels and analyze the use of message replication to create signal diversity. We observed that there is an optimum number of message replicas that minimizes outage probability and avoids high collision probability. We validate the proposed model using numerical simulations.