Routing Technology Of Satellite Mobile Communication Networks

Satellite networks will play a important part in the future, and its routing is close related with its performance. Compared to networks on the ground, the topology of satellite networks is changing all the time, so the routing algorithm of networks on the ground can not be applied to satellite networks. Presently there are three routing strategies for satellite networks, namely virtual topology routing strategy, virtual node routing strategy and topology dependent strategy.For virtual topology routing strategy, this paper establishes how to divide time slots for virtual topology routing strategy by means of calculating the average hops of the shortest path between satellites in the constellation and the variable ratio of inter-plane link length, and some examples about how to divide time slots are presented.For virtual node routing strategy, current papers mainly studied polar constellation, and this paper put forward a virtual node routing algorithm for Walker constellation. This algorithm calculates the directions to the next hop based on the minimum hops at first, and then choose the shortest path between the directions. When it chooses the direction for the shortest path, it constrains the search range to a parallelogram, and can decrease the complexity for searching. The space complexity of this algorithm is smaller than that of shortest path algorithm, and the error of its results is so small that it can be fit for our requirements.It is shown that hybrid constellation takes advantage over single layer constellation. A central routing algorithm for GEO\LEO constellations is put forward, which separates managements and services, that is to say: GEO satellites are responsible to collect information of routing, calculate and hand out the routing table; LEO satellites are in charge of sending information of routing, receiving route table and transmitting the services. All of these are simulated and verified in the OPNET environment.