Future 6G networks will operate across distributed and heterogeneous domain infrastructures, making conventional single-domain management insufficient for proactive, trustworthy automation. Network Digital Twins (NDTs) enable what-if analysis, AI-assisted optimization, and risk-free validation of control actions before deployment, yet monolithic end-to-end twins remain impractical due to scalability, fidelity, and cross-domain coordination challenges. Accordingly, this paper proposes a Digital Twin-enabled 6G architecture that exposes NDT capabilities as a specialized service domain within a multi-domain orchestration framework built on a state-of-the-art service-based 6G architecture. A DT Orchestrator interprets \textit{predictive} and \textit{prescriptive} what-if queries and composes domain-specific DT modules and simulators on demand, while decision authority remains with the requesting entity. Furthermore, a generalized workflow covers telemetry synchronization, simulation-based decision support, and closed-loop execution. The framework is demonstrated through a green-networking use case that couples a system-level O-RAN cellular digital twin component with a two-stage solar-allocation simulator, evaluated over a 105-base-station deployment in Poznan using simulative datasets. Joint coverage and renewable optimization reduces daily grid consumption by 28.5\% with 32 solar panels at the diminishing-returns threshold, with 17 base stations identified as both coverage-active and high-priority solar candidates as evidence that cross-domain NDT coordination enables sustainable, intent-driven 6G network management.

翻译：未来6G网络将运行于分布式的异构域基础设施之上，使得传统单域管理难以实现主动、可信的自动化。网络数字孪生（NDT）支持假设分析、AI辅助优化以及控制动作部署前的无风险验证，但端到端整体孪生因其可扩展性、保真度及跨域协调挑战而难以实际落地。为此，本文提出一种数字孪生赋能的6G架构，将NDT能力作为专业化服务域，嵌入基于最新服务化6G架构的多域编排框架中。数字孪生编排器解释"预测性"和"规范性"假设查询，并按需组合特定领域的DT模块与模拟器，而决策权仍保留在请求实体手中。此外，本文设计了一套通用工作流程，涵盖遥测同步、基于仿真的决策支持以及闭环执行。通过绿色网络用例验证该框架——该用例将系统级O-RAN蜂窝数字孪生组件与两阶段太阳能分配模拟器耦合，基于波兹南105个基站的模拟数据集进行评估。联合覆盖与可再生能源优化在收益递减阈值下，通过32块太阳能板将日均电网消耗降低28.5%，同时识别出17个兼具覆盖活跃性与高优先级太阳能部署潜力的基站——这证明跨域NDT协调能够实现可持续、意图驱动的6G网络管理。