Collision-Aware Random Access Control with Preamble Reuse for Industrial IoT

In industrial Internet of Things (IIoT), the existing access class barring (ACB) random access (RA) strategy suffers severe performance degradation with massive contention devices, due to high probability of access collision. In this paper, we propose a collision-aware (CA) ACB RA scheme by reusing the colliding preambles, to enhance the resource utilization. The proposed scheme employs dynamic adjustment of the ACB factor and the preamble resources for delay-sensitive and -non-sensitive devices, respectively. A joint optimization problem is formulated and solved to maximize the preamble utilization ratio (PAUR) subject to the delay constraints and the available preambles. The system performance is evaluated by a Markov Chain based analytical model. Simulation results verify the correctness of our analysis and also show that the proposed CA-ACB RA scheme significantly outperforms the existing ACB RA schemes in terms of PAUR, network throughput, and average access delay.