The topology of a satellite network can take many forms and there are variations on those. For geostationary satellites at Ku and C bands, two of the most common basic arrangements are:
- Star Topology
- Mesh Topology
The Star Topology employs Multipoint-to-Point connectivity
. Shown in the figure, each of the arrows is actually a point to point link between hub and remote site. About the hub
- The hub acts as the central control and management point for the network, reducing the need for remote-site technical support.
- The high-power broadcast from the hub can be received with relatively small dishes at the remote sites.
- At the hub, a large dish can more easily receive low-power transmissions from remote sites.
There is a single satellite hop between hub and remote; remote to remote communication must pass through the hub, resulting in a double hop. This can be used to transfer data messages but is not normally used for voice communication.
Basic arrangement of the Star topology, providing a hub in communication with several remote sites. Each bi-directional arrow represents point to point connectivity through a satellite, between one remote site and the hub.
Applications that need direct communications between remote sites can employ the Mesh topology.
There is a single hop for all connections, which are Point-to-Point
In a Mesh topology, all remote sites are peers:
- They can communicate with each other on an equal basis
- There is no central hub and each station is on its own as far as having an adequate size of antenna and transmitter.
- Peer nodes therefore tend to be physically larger and more costly that VSATs in a Star network
Some Mesh topology networks are demand-assigned so that links are set up only when needed. This reduces the steady-state capacity requirement on the satellite and thus saves bandwidth and money.
Demand assignment requires a control station to respond to requests for connections between Peer nodes. The Control station communicates with the Peer nodes using an independent channel that is not used to transfer actual user data.
Example of a Peer to Peer Mesh topology, indicating a control station for
demand assignment service.