VSAT communication network is composed of VSAT small station, main station and satellite transponder. The data VSAT satellite communication network usually uses a star structure.
Main station: The main station is also called the central station, which is the heart of the VSAT network. Like a normal earth station, it uses a large size antenna, and the diameter of the antenna is generally about 3.5m to 8m (Ku band) or 7m to 13m (C band). In a VSAT satellite communication network mainly focused on data business, the main station is both the business center and the control center. The main station is usually put together with the main computer or connected to the main computer through other (terrestrial or satellite) lines as a business center (the central node of the network). At the same time, there is also a network control center (NCC) in the main station responsible for monitoring, management, control and maintenance all the network. In a VSAT satellite communication network mainly focused on voice service, the control center and the service center can be either in the same station or in the different station. Usually, the station where the control center located is called the main station or the central station. Since the main station is involved in the operation of the entire VSAT network, its failure will affect the normal operation of the entire network, so it must be backed up. In order to facilitate recombination, the main station generally adopts a modular structure, and the devices are interconnected by means of a high-speed local area network.
VSAT small station: VSAT small station is composed of small aperture antenna, outdoor unit (ODU) and indoor unit (IDU). Under the same condition, such as the same frequency band and the same transponder condition, the antenna of the small station of the voice VSAT network is significantly larger than that of the data VSAT station which only communicates with the main station, since the voice VSAT can directly communicate among the small stations.
Satellite transponder: generally, the transparent transponder of geostationary satellite working in C or Ku band is adopted. C-band transponder is mainly used in the first generation VSAT network. From the second generation VSAT, Ku band is mainly used. The specific band to be used depends not only on the VSAT equipment itself, but also on whether there are available on-board resources, that is, whether there are Ku band transponders available. If not, only C-band can be used.
The network structure of VSAT satellite communication network can be divided into star network, mesh network and hybrid network (Star + mesh).
I.The VSAT network with star structure is most suitable for the application scenario of point to multipoint communication such as broadcasting and collection. For example, national or global units with many branches use it as a private data network to improve their automatic management, release or collect information.
II. The VSAT network with mesh structure (star structure is still used for channel allocation, network monitoring and management) is more suitable for the application scenario of point-to-point real-time communication, such as the establishment of VSAT private telephone network in the unit.
III.The VSAT network with hybrid structure is most suitable for the application environment of point-to-point or point to multipoint integrated service transmission. The VSAT network with this structure uses mesh structure for point-to-point transmission or real-time service transmission, and uses star structure for point-to-multipoint transmission or data transmission. Various multiple access modes can be used in star and mesh structures. The VSAT network with this structure integrates the advantages of the first two structures, allowing two VSAT stations with large differences (i.e. small stations for small users and large stations for large users) to coexist in the same network. It can carry out comprehensive service transmission, and can select the most appropriate multiple access mode.
