A Delay-Sensitive Multibase-Station Multichannel Access System for Smart Factory

The intelligence of industrial production depends on real-time and reliable transmission and timely feedback of information in the Industrial Internet of Things (IIoT) systems. However, the scarcity of spectrum resources, a harsh industrial electromagnetic environment, and a need for real-time processing of massive traffic have posed severe challenges to the real-time and reliable access of the MAC layer. Aiming to solve the real-time transmission problem in the IIoT system, a delay-sensitive multibase-station multichannel access scheme is proposed. First, a multibase-station multichannel access model for real-time transmission is developed. The way to match sensing nodes with base stations and channels is formulated as a delay-sensitive multibase-station multichannel access (DMMA) problem. Moreover, it is theoretically proved that the DMMA problem is NP-Hard. Finally, a delay-sensitive greedy schedule (DG-Schedule) scheme based on the minimum deadline priority is proposed to obtain a feasible solution to the DMMA problem. According to experiments on the TI CC2530, DG-Schedule can reduce packet loss by 11% and average latency by 88% compared to CSMA/CA. Therefore, the DG-Schedule scheme is more suitable for IIoT scenarios.