The sixth generation (6G) of wireless networks will require fundamentally new orchestration paradigms to meet stringent requirements for ultra-low latency, high reliability, and pervasive intelligence. Network slicing emerges as a key enabler to support diverse services with customized quality-of-service (QoS) guarantees. However, dynamic and fine-grained slice management poses significant challenges in terms of real-time provisioning, SLA assurance, and cross-layer observability. In this paper, we propose a novel Digital Twin as a Service (DTaaS) framework that embeds per-slice digital twins (SDTs) into the orchestration loop. Each SDT maintains a synchronized, real-time representation of its slice, leveraging multi-domain telemetry and deep sequential models to predict traffic evolution and SLA risks. The framework introduces modular intelligence layers, programmable interfaces, and edge-embedded decision-making to enable proactive provisioning, adaptive scaling, and closed-loop SLA assurance. Mathematical formulations for fidelity measurement, predictive control, and optimization objectives are provided to ensure rigor and transparency. Evaluation results demonstrate that DTaaS significantly improves SLA compliance ratio, reduces resource over-provisioning, and lowers average SLA violation probability, offering a scalable and reliable orchestration approach for 6G networks.

翻译：第六代（6G）无线网络需要全新的编排范式，以满足超低延迟、高可靠性和普适智能的严格要求。网络切片成为支持多样化服务并保障定制化服务质量（QoS）的关键使能技术。然而，动态且细粒度的切片管理在实时供给、服务等级协议（SLA）保障和跨层可观测性方面带来了重大挑战。本文提出一种新颖的数字孪生即服务（DTaaS）框架，该框架将每切片数字孪生（SDT）嵌入编排闭环中。每个SDT通过融合多域遥测数据和深度序列模型，维护其对应切片的同步实时表征，以预测流量演变和SLA风险。该框架引入了模块化智能层、可编程接口和边缘嵌入式决策机制，以实现主动供给、自适应扩缩和闭环SLA保障。文中提供了保真度度量、预测控制和优化目标的数学表述，以确保严谨性和透明度。评估结果表明，DTaaS显著提升了SLA合规率，减少了资源过度配置，降低了平均SLA违反概率，为6G网络提供了一种可扩展且可靠的编排方法。