## 3 Design of a Digital Satellite-Borne Base Station for Quick Functional Reconfiguration  
The horizontal shared network architecture used by the digital satellite-borne base station is a new access network architecture with physical centralization, logical wide-area distribution, multi-point cooperative transmission, and intelligent dynamic sharing of resources. It combines computing, communication, and storage in one network. In order to achieve cost savings (statistical resource reuse), lower energy consumption, and network optimization, the architecture may dynamically construct the logical network of each network system needed for services in real time and runtime global optimization of the network. Figure 1 depicts the physical connectivity of the digital satellite-borne base station system. The system is made up of several satellites, each of which has an RF digitizing unit, an RF front-end processing unit, a baseband processing unit, and a protocol processing unit. High-speed inter-satellite links are used to exchange data between the satellites. Baseband processing units on numerous satellites constitute a baseband processing resource pool, and protocol processing units on many satellites form a protocol processing resource pool. Both of these processing units are managed by the global resource control center, which is on the ground. The logical connection of the digital satellite-borne base station system, as shown in Figure 2, consists of a multi-star, multi-system protocol processing resource pool, baseband processing resource pool, RF front-end processing unit, and RF digitizing unit to complete the signal and information processing architecture of the whole station. Among them, the protocol processing resource pool is realized through virtualization technology, which is composed of multi-star protocol processing units, and the protocol processing function of each star is programmed and loaded by the global resource control  
center. The baseband processing units have quick functional reconfigurability to enable waveform software dynamic loading. The baseband processing units of various stars come together to form a baseband processing resource pool. Additionally, the global resource control center schedules and loads the particular baseband processing function of each star. The administration of satellite-borne computing resources, the scheduling management of baseband processing units, the scheduling management of protocol processing units, and the task migration control are all handled by the global resource control center on the ground. The infrastructural capabilities in this system are controlled and abstracted in a uniform manner, then dynamically allocated to virtual beams and channels as needed through the system's unified centralized resource control. Using the open interfaces offered by the digital satellite-borne base station system, the global resource control center can dynamically add, configure, manage, monitor, upgrade, and expand virtual beam and channel devices, configure wireless resource management algorithms, and carry out network optimization without being aware of the precise location and physical configuration of the actual physical entities (baseband processing resources, protocol processing resources, etc.). Figure 1: Physical architecture of digital satellite-borne base station system. Figure 2: Logical architecture of digital satellite-borne base station system. According to the characteristics of multi-star and multi-protocol information transmission network processing resources, the three-layer virtualization model of a digital satellite-borne base station architecture is defined as shown in Figure 3.  
The digital satellite-borne base station architecture network resource virtualization model is divided into three logical layers, which are the physical resource layer, virtualized resource layer, and virtualized function layer. All three layers entities are managed by the global resource control center.