Interference-Aware Spreading Factor Assignment Scheme for the Massive LoRaWAN Network

In LoRaWAN, end devices of class A adapts pure ALOHA for the channel access where interference occurs due to the use of same/different spreading factors (SFs) which leads to high packet loss. In this paper, we propose an Interference-Aware Spreading Factor Assignment (I-ASF) algorithm to counteract against the interference occurred due to the same/different SFs. The I-ASF algorithm considers gateway sensitivity, the interfered SFs, overlaps time of the collided packets, and the interfering energy in order to assign SF to decrease the significance of the interference. Thus, this behavior leads to an optimal assignment of SFs which minimizes the ToA for every end device. As a result, IASF reduces the collision and enhances the packet success ratio. Simulation results show that I-ASF algorithm outperforms both the existing distance-based and random-based spreading factor allocation schemes in terms of packet success ratio.