Massively dense deployment of Internet of Things (IoT) devices has put a stringent requirement on cellular networks to provide convenient service for not only human type traffic (HTC) but also for bursty traffic for IoT devices. Any bottleneck in the random access process means the bottleneck of the entire system because it is the first step before scheduled access. Access class barring (ACB) scheme is one of the key schemes in long term evolution advanced (LTE-A) to control the congestion in a random access process in which the access of some devices is barred based on a parameter, ACB factor, to relieve the congestion. In this paper, we analyze the ACB factor and criteria of its selection as the optimal selection of the ACB factor is essential for the maximum throughput of the system. The metrics used in the analysis of the ACB factor are total service time (TST), access delay and maximum collision, success, and idle probabilities with fixed and optimal ACB factor. Simulation results in MATLAB provide the complete picture of the behavior of the ACB factor and its control, used in the random access process.

物联网（IoT）设备的大规模密集部署对蜂窝网络提出了严格的要求，以不仅为人类流量（HTC）提供便利的服务，而且为IoT设备的突发流量提供便利的服务。随机访问过程中的任何瓶颈都意味着整个系统的瓶颈，因为这是计划访问之前的第一步。接入类别限制（ACB）方案是高级演进高级（LTE-A）中控制随机访问过程中拥塞的关键方案之一，在该过程中，基于参数ACB因子禁止某些设备的访问，缓解交通拥堵。在本文中，我们分析了ACB因子及其选择标准，因为ACB因子的最佳选择对于系统的最大吞吐量至关重要。ACB因子分析中使用的度量标准是总服务时间（TST），访问延迟和最大冲突，成功以及具有固定和最佳ACB因子的空闲概率。MATLAB中的仿真结果提供了ACB因子及其控制的行为的完整图景，用于随机访问过程。