Satellite Communication Networks Simulation Based On OPNET And HLA

LEO(Low Earth Orbit)satellite communication system can not only achieve global continuous coverage, but also has advantages with low propagation delay and pass loss. Therefore, it is expected to play a significant role in the future satellite communications on both civil and military fields. Considering the complexity of the structure and function of satellite communication networks, and the swift renewing of communication technique, it is highly important and necessary to use simulation methods to study satellite communication networks.This thesis has firstly studied the simulation and modeling techniques in OPNET, the theory of satellite's orbit and characteristics of continuous coverage with handoffs in LEO satellite networks, and then the dynamic change of networks'topologies has been analyzed theoretically. A simulation system of Iridium satellite network has been modeled and the simulation results including the routing table, SNR and end-to-end delay have been analyzed. This simulation platform not only provides accurate quantifications of network's behavior, but also could act as the guidance for further LEO satellite networks researches theoretically and experimentally.This thesis has also studied how to realize the key technology such as data exchange, time advance, simulation management among different programs and systems under high level architecture. Another important part in this thesis is to design a federation constructed by a control federate and an OPNET federate. The network simulation model in OPNET has been designed to achieve data interaction and maintain time synchronization with other systems through HLA_interface node module. The controller federate is designed to advance federation time, send interactions to change the orbit parameters of the satellite node in the OPNET federate and receive result from OPNET federate. The dynamic control of simulation process and the real-time update of simulation for Iridium satellite communication system are achieved on multiple computers. It means that a large scale of global network simulation system can be built up through HLA over large amounts of distributed machines.