An AoI-Aware CSMA/CA MAC Protocol with RIS-Assisted Two-Stage Channel Sensing for IIoT

Abstract

With the rapid development of the Industrial Internet of Things (IIoT), sensor nodes often face harsh channel conditions, leading to transmission failures and increased Age of Information (AoI), which cannot meet the real-time requirements of latency-sensitive systems. To solve this problem, this paper proposes an improved Medium Access Control(MAC) protocol based on the Carrier Sense Multiple Access with Collision Avoidance(CSMA/CA) protocol, integrating a two-stage channel sensing decision mechanism and RIS-assisted threshold control. The protocol abandons the backoff retransmission mechanism, adopts a two-stage channel sensing strategy, and takes minimizing the average and peak AoI as the optimization goal. Simulation results show that the proposed scheme significantly outperforms traditional schemes in normalized average AoI and normalized peak AoI, effectively balancing transmission reliability, RIS overhead and AoI performance. It provides a feasible solution for real-time status updates in IIoT and promotes the practical application of RIS-assisted communication technology.