Optimization Of Routing Protocol And Effective Transmission Mechanism For Satellite Laser Network

As mobile communication enters the sixth-generation(6G)era,the demand of people on communication services is increasing rapidly.Efficient,convenient,high-quality and full-coverage communication is more and more favored by people.Terrestrial network provides users with high-speed and large bandwidth communication service,but it relies on the network infrastructure.In a remote mountain or plateau,the base station is therefore difficult to establish a communication network.And the area with the whole domain,full coverage,especially natural disasters,the base station owns high damage probability and difficulty of maintenance.The terrestrial communication networks may be unavailable in the region.Satellite optical network and terrestrial network are integrated to constitute an important part of the 6G.Compared with the terrestrial network,satellite optical network has characteristics like:global coverage,far transfer distance,broad bandwidth and not restricted by geographical environment;continuous network services,such as area detection,weather prediction,emergency rescue and etc;achieves full-time,full-domain,full-coverage of efficient communication.At present,with the increasingly development of satellite communication technology,the satellite network should meet the increasing requirements of coverage area,Quality of Service(QoS)and robustness.However,temporal dynamics topology network and hardware resources limit the development of satellite communication network.Routing protocol affects the synchronization of link state and service transmission path between satellites,which directly affect the overall performance of the network.It is especially important to choose appropriate routing protocol to ensure ensure the interaction of link state.Traditional routing protocols are originated from terrestrial communication network,which is not suitable for frequent routing convergence,scenarios caused by temporal dynamics topology,and the generated transmission path does not take link bandwidth and effect time into account.The routing scheme thus need to be optimized in satellite network.In this paper,OSPF protocol combining with the characteristics of satellite optical network is optimized.Main researches and innovations are as follows:1)Based on ephemeris,the self-updating mechanism for link state database is introduced.The topology planning results are calculated and formed link plan table by the ground station,which is regularly injected into the satellite directly connected to the ground station.The injected satellite distributes the link plan table to all the satellites through flooding mechanism.After receiving link plan table,the satellite periodically updates the link state database and the neighbor information of the interface,so as to reduce the link information interaction triggered by topology changes and eliminate the route convergence caused by link state database synchronization.At the same time,the original OSPF neighbor monitoring mechanism is retained to ensure that OSPF can correct itself in a timely manner when planning information or links failure.2)Link effect time and effective bandwidth are added to the link state database.We optimize the original Shortest Path First(SPF)route calculation process,and introduce the Constrained Shortest Path First(CSPF)route calculation process.In the route calculation,the link effect time and effective bandwidth are considered to get routes that meet bandwidth requirements and have longer link lifetime for service transmission.3)Considering the limited handling ability and storage capacity of satellite,storing and forwarding a large amount of data will bring a great burden to the satellite.In this paper,an effective transmission mechanism is introduced and a data compression algorithm is adopted to compress the large amount of data in the link plan table,which effectively reduces the amount of data transmitted in packets.In this paper,two test environments,hardware and software,are selected to verify the above scheme,which include the satellite hardware environment simulated on the CPU development board and FPGA development board equipped with VxWorks system,and OMNeT++software simulation environment.The results show that the improved OSPF protocol can eliminate the route convergence caused by predictable topology changes and effectively reduce packet loss rate and delay performance.