## 3 Design of a Digital Satellite-Borne Base Station for Quick Functional Reconfiguration
Among them, the physical resource layer is located at the lowermost layer of the digitized satellite-borne base station system and consists of various infrastructures. The infrastructure includes baseband processing equipment, protocol processing equipment, RF front-end processing equipment, RF digitizing equipment, etc. Each device consists of corresponding processors, memory, accelerator, I/O interfaces, etc. The devices on the same satellite are interconnected by wired high-speed links, and the devices across satellites can be interconnected by high-speed inter-satellite links. Each device has a certain processing capacity, i.e., the maximum number of tasks that can be handled by a full load. The processing capacity is quantified by dividing it according to the characteristics of satellite communication resource processing: for example, how many subcarriers of bandwidth are handled as the basic unit. The finer the granularity of capacity division, the greater the management overhead that may result. The virtualization resource layer focuses on resource virtualization and pooling, how a subset of virtual resources are allocated, the mapping relationships between virtual and physical resources, resource migration, and how to provide a virtual resource view upwards. Virtualized resource management is one of the key factors to realize efficient utilization of each virtualized and pooled resource of a digital satellite-borne base station system. The virtualized functional layer sits above the virtualized resource layer and primarily enables programmable and dynamically customizable management of virtualized functional units while facing the multi-star multi-protocol transport network. The virtualization function layer applies for corresponding virtual resources from the virtual resource pool view according to the service requirements, and forms protocol-specific processing virtualization function units and baseband processing virtualization function units by dynamically combining and binding the frequency and bandwidth resources, baseband  
Figure 3: Resource virtualization model of digital satellite-borne base station system. processing resources, protocol processing resources and management control resources required for processing tasks. The three-layer virtualization model of the digital satellite-borne base station architecture is abstracted in layers that serve each other. The physical resource layer masks physical devices to the upper layers and abstracts the infrastructure as a service for the virtualized resource layer. The physical resource layer abstracts virtualized resources to the physical resource view. The virtualization resource layer, in turn, aggregates the virtualization resources abstracted from different physical devices and provides a virtualization resource view in the form of a new resource pool that is used by the virtualization functional layer. The virtualization function layer then obtains different resources from the virtualization resource pool view to combine into logically independent virtualization function units. With three-layer virtualization, the digital satellite-borne base station system only needs to concentrate on the transparent use of resources, focusing on network services and network optimization, such as the deployment of network optimization algorithms. This eliminates the need to pay attention to the type and location of the physical infrastructure entirely.