In this work, we provide a simple yet tight analytical approximation of the packet loss rate in the error floor region for a non-orthogonal multiple access (NOMA)-based irregular repetition slotted ALOHA (IRSA) scheme. Considering an Internet of Things (IoT) scenario, users randomly select both the number of replicas based on a designed degree distribution and the transmission power from predetermined levels, while successive interference cancellation (SIC) is performed at the receiver. Our derived packet loss rate expression in the finite length regime is promptly evaluated. Its accuracy is validated through Monte-Carlo simulations, demonstrating a strong match across channel loads, including those beyond the low load regime

翻译：本文针对基于非正交多址接入的不规则重复时隙ALOHA方案，提出了一种简洁而精确的误码平层区域分组丢失率解析近似方法。在物联网场景下，用户依据设计的度分布随机选择重复次数，并从预设功率等级中随机选择发射功率；接收端则执行连续干扰消除。我们推导了有限码长条件下的分组丢失率表达式，并进行了快速评估。通过蒙特卡洛仿真验证了其准确性，结果表明该表达式在不同信道负载（包括超出低负载范围的场景）下均能保持高度匹配。