Research On The Architecture And Routing Protocol Of Double-layered Satellite Network

Satellite network based on ISLs(inter-satellite links)is the core component of SIN(Spatial Information Network),with global coverage,geographic and distance factor is not sensitive,strong survivability,strong scalability and other advantages.Combine different types of satellite with different orbital heights effectively to establish the multi-layer satellite network,which can support the communication servers for SIN with large-capacity,high-quality,high reliability and diversified communication services,such as ocean navigation,emergency rescue,navigation and positioning,air transportation,aerospace monitoring and other major applications.Now,the research on multi-layer satel ite network,has became the focus of SIN for many countries.There are two main works of the paper,which are as follows: Firstly,by analyzing the existing multi-layer satellite network structure,we found that in consider of stability,when there is a “sight access” between different layers of satellites,it's necessary to install a pair of inter-layer transceivers.Which result difficult in satellite manufacturing,and network structure is also very complex.To solve that,the paper proposes a new LEO/MEO double-layer satellite network structure,which is designed based on LEO satellites grouping,each MEO satellite is a manager of one LEO group.One LEO(Low Earth Orbit)satellite only establishes an inter-layer link with just one MEO(Medium Earth Orbit)satellite,and one MEO satellite doesn't establish links with all LEO satellites in its “sight access”,it choose part of them,just one LEO group.Secondly,there are lots of problems in the existing multi-layer satellite network routing protocol,such as collecting topology information is complex,the overhead of communication is large,and they can't adapt to the topology of multi-layer satellite network changes so frequently,and the calculation process of route is complex and so on.Based on SGRP,the paper proposes a new LEO/MEO double-layer satellite network routing protocol,it's designed based on pre-storing the data of switching information between satellites in different layers,and divided the communication into two stages.That is,by using the pre-stored data,each LEO satellite update its manager in time,in order to complete the LEO satellites grouping,and LEO satellites don't need to send their information about topology to MEO satellites,and each LEO group summarizes the topology information and calculates the routes in the group.Similarly,by using the pre-stored data,each MEO satellite update its ruled members of LEO group in time,then communicate with other MEO satellites,in order to calculate the route.So that,the routing protocol we proposed,can divide communication into SDD and LDD,which complete the forwarding and transmission of communication data.In the paper,in order to do network simulation,we use STK and OPNET to do analysis,that contains analyze the stability of the network structure and the performance of routing protocol.The simulation shows: the designed LEO/MEO double-layer satellite network structure is stable in general;and the designed LEO/MEO double-layer satellite network routing protocol has good performance,comparing with SGRP,the designed routing protocol has the better delay characteristic and lower packet loss rate.