Font Size: a A A

Research On The Design And Optimization Of Inter-satellite Link Networks In Global Navigation Satellite Systems

Posted on:2019-04-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:J H HuangFull Text:PDF
GTID:1368330623450340Subject:Information and Communication Engineering
Abstract/Summary:PDF Full Text Request
The new generation of global navigation satellite systems will adopt the technology of inter-satellite links(ISLs).The ISLs are established not only for inter-satellite ranging but also for inter-satellite communication,and connect the various satellites through interconnection.Coupling the high speed high-bandwidth directional link with the time division multiple access(TDMA),the trend of ISL gradually develops into an intermittently connected ISL network.The intermittently connected ISL network is different from the GPS ISL networks in which wide beam antennas are used,and poses challenges for the network communication performance.We try to improve the communication performance of ISL networks while satisfying the measurement requirement at the same time.The major innovative works of this thesis are as follow:First,we propose a simple to implement framework for the GNSS ISL contact plan design.In the proposed framework,the contact plan is optimized at two levels: the “contact sequence and slot length” and the “lifetime of each contact sequence”.The contact sequence and slot length are optimized using simulated annealing algorithm.The lifetime of each contact sequence is optimized based on the visibility between satellites and stations.The delay determined by contact plan,the communication bandwidth between satellites visible to stations and satellites not visible to stations,and the weighted dilution of precision are combined as the optimization object by physical programming.The maximum uploading/downloading data rate is improved by 100% by our optimization method,and the average delay is lowered by 75%.Second,we consider the problem of routing when the queueing information of satellites is not known in real time.The communication delay in intermittently connected ISL network is analyzed.Based on the analysis,we propose several routing algorithms,namely local information based routing,local and neighbour information based routing,information of satellite visible to station based routing,and network information based routing.The proposed algorithms outperform the traditional topology based routing in packet loss ratio and average end-to-end delay in most cases.The maximum uploading data rate is improved by 100%,and the maximum downloading data rate are improved by 25% by our routing algorithms.Third,we propose an efficient utilization of the adaptive modulation and coding(AMC)scheme for ISLs in the GNSS.A novel method,based on inter-satellite distance,is presented for choosing the modulation and coding scheme.This AMC technique is implemented based on the inter-satellite distance,aimed at keeping the bit error rate below a target limit.Simulation results show that,in cases where the inter-satellite distance is short,the throughput of the proposed AMC schemes is nearly six times that of a fixed modulation and coding scheme under the premise of the same transmission power.We also find that the scanning angular scope of MEO antenna has an obvious effect on the average spectral efficiency in the network.The maximum uploading data rate is improved by 25% when AMC is used and scanning angular scope is 80 o.Furthermore,we evaluate the benefits of our ISL network optimization approach in different satellite network sizes.The maximum uploading data rate is improved by 200%-500% in different satellite network sizes by our approach.With the increase of the network size,the merit of our approach is more obvious.Lastly,we summarize the research work and present the future work.The research results can be used in the ISL network design and optimization of Chinese satellite navigation system.
Keywords/Search Tags:GNSS, Inter-satellite link, Contact plan, Topology design, Contact sequence, Snapshots division, Intermittent connected networks, Satellite routing, Rate adaption, Adaptive modulation and coding
PDF Full Text Request
Related items