LoRaWAN is one of the most suitable communication protocols for the IoT applications that require low power over long-range communication. However, the LoRa network suffers from scalability, low data rate, and other performance issues that significantly affect the network performance. The study of the optimal spreading factor allocation can overcome these issues and help to improve the network performance. Hence, this article puts forward the state-of-the-art literature review on the Spreading Factors Allocation schemes for the LoRaWAN. Industry and academia have done an extensive research to address the issues related to optimal resource allocation, like spreading factor allocation to the spatially distributed end-devices of the network. Most of the problems concerning spreading factor allocation are being explored and resolved. Therefore, this paper reviews and compares various spreading factor allocation schemes proposed by the researchers. Furthermore, we provide a summary of the different review studies of the LoRaWAN. The literature presented in this paper motivates researchers to examine other aspects of spreading factor allocation schemes to improve the LoRa network performance.

LoRaWAN 是最适合需要低功耗远距离通信的物联网应用的通信协议之一。然而，LoRa 网络存在可扩展性、低数据速率和其他显着影响网络性能的性能问题。最优扩频因子分配的研究可以克服这些问题，有助于提高网络性能。因此，本文提出了关于传播因子分配的最新文献综述LoRaWAN 方案。工业界和学术界已经进行了广泛的研究来解决与最佳资源分配相关的问题，例如对网络空间分布的终端设备的扩频因子分配。大多数关于扩频因子分配的问题正在探索和解决。因此，本文回顾和比较了研究人员提出的各种扩频因子分配方案。此外，我们提供了对 LoRaWAN 的不同评论研究的总结。本文介绍的文献促使研究人员研究扩频因子分配方案的其他方面，以提高 LoRa 网络性能。