A Low-Latency Random Access Scheme by Multichannel SIC for Industrial IoT

Low latency is a prerequisite for real-time applications, and random access is almost an inevitable choice for large-scale wireless networks. In this article, we consider how to decrease access delay in random access manners for the industrial Internet of Things. We propose a novel scheme by integrating multiple subchannels on the user equipment (UE) side with message-level successive interference cancellation (SIC) on the sink side. Specifically, for any UE that starts an uplink transmission, it just stochastically chooses parts of its subchannels and then simultaneously transmits the same message on them without any power control. On the sink side, the sink decodes signals from UEs using SIC across multiple subchannels. Based on the proposed multichannel SIC scheme, minimizing the access delay in the random access manner is equivalent to minimizing the probability of decoding deadlock. Based on the mathematical method of density evolution and the help from the differential evolution algorithm, an optimal distribution for choosing subchannels is presented. With the optimal distribution, the average access delay is minimized.