LAUSR

Owing to provision of a long-range and robust link, LoRa technology has drawn attention for the use in industrial data collection networks. This article proposes a real-time LoRa protocol that can effectively deal with both periodic and aperiodic data. The slots in a frame are logically partitioned such that they are first scheduled for periodic data by a slot scheduling algorithm, and then, the remaining unscheduled slots are used for event-driven aperiodic data. In this logical frame partitioning, the unscheduled slots appear in an interleaved fashion so that aperiodic tasks can transmit data with low delay and fairness while every periodic task still completes data transmission before the beginning of the next period. To deal with the problems of data collision and traffic congestion for aperiodic data, a two-level collision avoidance scheme is proposed that adopts the notion of a contention window and a delay slot. According to simulation, not only can the proposed protocol guarantee the timely delivery of periodic data but it can also deal with aperiodic data with high reliability, fairness, and low delay, compared with other recent protocols.