# Toward Integrated Satellite Operations and Network Management: A Review and Novel Framework
## 2 State of the Art
### Satellite Operations and Management Systems
#### 2.2.2 Operations in Persistent Connectivity Constellations  
The development of SDN has revolutionized the landscape of network management by decoupling the control plane from the data plane, enabling more dynamic, flexible, and programmable network architectures. SDNs offer a robust framework for addressing these challenges. By leveraging centralized control and programmability, SDNs facilitate efficient traffic management, resource allocation, and fault tolerance in NTNs. This capability is crucial for maintaining the performance and reliability of these networks, which operate in dynamic and often unpredictable environments. Furthermore, SDNs enable seamless integration of NTNs with terrestrial networks, creating a unified and cohesive global communication infrastructure. This integration is essential for achieving ubiquitous connectivity, enhancing network resilience, and supporting various applications from remote sensing to global broadband internet access. Through advanced routing protocols, traffic engineering, and virtualization techniques, SDNs provide the tools to manage the heterogeneity and scale of integrated terrestrial and non-terrestrial networks. In [68], the challenges of orchestrating the heterogeneous resources of an integrated network are identified. Efficient and intelligent network management is proposed with a SDN control plane that includes terrestrial and satellite controllers for unified, integrated network control. In [69], authors acknowledge that current STIN paradigms face challenges such as unstable ISL, inefficient spectrum sharing, and interoperability issues between SatCom and TerCom networks. Additionally, STINs require more intelligent operation systems to manage resources effectively and implement advanced functions like predictive maintenance. They concur that the solution is an SDN architecture with software-defined satellites for dynamic configuration of satellite functions, distributed controller deployment to improve interoperability, and scenario/service-oriented flexible networking to adapt to customized network requirements. In [70], the SDN controller placement problem to satellite networks is extended. This problem can be transformed into a task assignment problem to better align with SNOs. NFV represents a transformative approach to network architecture, wherein traditional network functions are decoupled from dedicated hardware and implemented as software instances running on commodity hardware. This virtualization reduces the dependency on specialized hardware and enhances network operations' flexibility, scalability, and cost-efficiency. NFV is emerging as a key enabler for integrating satellite and terrestrial networks. Virtualizing network functions allows for the dynamic deployment and scaling of network services across satellite and terrestrial components. This capability is essential for addressing the unique challenges of satellite networks, such as varying latency, bandwidth constraints, and dynamic topologies. When combined with SDNs, NFV provides an even more robust framework for the integral management and orchestration of satellite networks. SDNs offer centralized control and programmability, while NFV enables the rapid deployment and adjustment of network functions in response to changing network conditions. They facilitate comprehensive and flexible network management, enhancing satellite-terrestrial integrated networks' performance, reliability, and efficiency. A critical component in this framework is MANO, which plays a pivotal role in deploying and operating NFV-based systems. MANO encompasses the functions required for the provisioning and lifecycle management of network services and virtualized resources. It ensures that the virtualized infrastructure and network functions operate harmoniously, providing the necessary automation, coordination, and optimization.