Non-terrestrial networks (NTN) have been standardized by the 3rd generation partnership project (3GPP) as a key component of future 6G systems to enhance coverage and resilience. In particular, NTN technologies such as low-earth orbit (LEO) satellites, high-altitude platform stations (HAPS), and unmanned aerial vehicles (UAVs) are expected to support terrestrial networks (TN) during extreme events and disasters. In this paper, we present a lightweight system-level simulator for evaluating post-failure fallback behavior in integrated TN-NTN wireless networks under a partial-failure disaster model. The simulator follows 3GPP Rel-17/18 modeling principles, supports probabilistic terrestrial next-generation node B (gNB) failures, and service migration to NTN. The simulator supports comparative analysis of throughput, packet reception ratio (PRR), and latency under different user loads, disaster severities, and NTN provisioning levels. Results show the expected capacity-delay tradeoff of terrestrial operation, the reliability and stability of non-terrestrial service, and the balanced resilience behavior of hybrid TN-NTN operation. The proposed framework provides a tractable tool for studying wireless network resilience and traffic management in future integrated 6G mobile systems.

翻译：非地面网络（NTN）已被第三代合作伙伴计划（3GPP）标准化为未来6G系统的关键组成部分，以增强覆盖范围和韧性。具体而言，低地球轨道（LEO）卫星、高空平台站（HAPS）和无人飞行器（UAV）等NTN技术有望在极端事件和灾害期间支持地面网络（TN）。本文提出了一种轻量级系统级仿真器，用于评估在部分故障灾害模型下集成TN-NTN无线网络中的故障后回退行为。该仿真器遵循3GPP Rel-17/18建模原则，支持概率性地面下一代节点B（gNB）故障以及向NTN的服务迁移。该仿真器支持在不同用户负载、灾害严重程度和NTN供应水平下对吞吐量、数据包接收率（PRR）和时延的比较分析。结果表明，地面操作的容量-时延权衡、非地面服务的可靠性和稳定性，以及混合TN-NTN操作的平衡韧性行为。所提出的框架为研究未来集成6G移动系统中无线网络韧性和流量管理提供了一种易于处理的分析工具。