# 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
Advances in software-defined networking for satellite systems have introduced distributed SDN control approaches for reliable satellite-terrestrial integration [71], addressing the unique challenges of dynamic topologies and varying connectivity in space-based networks. These approaches complement autonomous orchestration frameworks that enable multi-mission coordination across heterogeneous satellite constellations [24]. MANOs in terrestrial networks are not autonomous nor schedulable. In [72], the challenges of deploying VNF on the satellites of a constellation network are tackled. The key enabling processes to deploy VNF on satellites are the automated mapping and scheduling of these functions in SDN-enabled networks. The existing literature emphasizes VNF scheduling in terrestrial networks, leaving a gap in addressing the dynamic topology of STINs. This challenge is addressed in [73], where a spatial-aware extension for state-of-the-art MANO is proposed. In [74], authors also tackle the challenge of VNF deployment on satellites, and they propose a distributed CN onboard the satellites containing the necessary network functions to operate with minimal ground CN interaction. Another example of orchestration and management approach for HCC is presented in [75]; three different cooperation models between satellite and terrestrial networks are identified, and intelligent orchestration is required to dynamically decide which of the three cooperation models is used for each service. In [76], traditional TTC is adapted with a novel architecture based on satellite Internet. Two key technologies are identified: dynamic network scheduling management and task planning under complex constraint conditions to achieve efficient operation of the proposed system. Some authors in the literature present management architectures that allow for the control and orchestration of NFV-and-SDN-enabled satellite networks. In [77], a testbed for the network management of a relay node is presented based on trusted non-3 GPP access architecture. They propose that the entire NTN is a virtualized layer of the integrated network and that it will be operated using OSM. The testbed uses a GEO satellite for the NTN layer, and authors claim that this forms a basis for a plug-and-play approach to the integration of satellite and terrestrial 5G network operators. Authors in [78; 79] present resource management architectures for multi-layered satellite networks. In [78], an architecture based on an intelligent AI-driven MANO is presented that generates network slices to comply with user service demands. The architecture is divided into three abstracted resource management functions, which work independently with their close-loop AI training: access-level (encompassing satellites, GSs, and CN), service-level, and resource-level. Authors in [79] provide a detailed example of managing a multi-layered constellation. They propose a clustering algorithm where SDN controllers are deployed as masters in the MEO layer and slaves at the LEO layer. However, each LEO slave satellite is the local controller of a LEO satellite cluster to reduce queuing and network complexity. They present how the MEO satellites collect network data through the LEO cluster leaders, decide resource slicing based on these data and the user service, and how LEO controllers allocate these resources in their local cluster. An architectural framework for the control plane of integrated networks is presented in [80]. The authors present a centralized, integrated network control that aggregates the four different control planes: RAN, NTN, CN, and data network. The authors describe the NTN individual network control system in detail. This NTN control system receives control commands from the integrated network control system and sends aggregated control data back to it. Similarly, it interacts with the physical components of the NTN segment by sending control commands and receiving control data from them. The NTN control system comprises several architectural modules.