Research On The Centerless Ad Hoc Network Of Micro-nano Satellite Based On LoRa

The on-board resources of micro-nano satellite are limited,which makes the formation networking face many problems such as difficult distance maintaining,dynamic node changes,unstable connection and tough relay.Therefore,it is necessary to realize the centerless dynamic access in the process of satellite networking.LoRa is a newly developed wireless communication technology applied in the Internet of Things,it has the advantages of strong anti-interference ability to spread spectrum transceiver,high dynamic adaptability,high receiving sensitivity and low cost,and has been widely used in space interconnection.In this paper,a kind of adaptive networking scheme for micro-nano satellite is proposed based on LoRa,which can realize the Ad hoc network access in dynamic environment,and it has the advantages of wide ground coverage and fewer satellites involved.The main research contents of this paper are as follows:1)The existing micro-nano satellite constellation networking schemes at home and abroad and the problems they face are summarized in this paper.Moreover,the characteristics and advantages of LoRa technology,the multiple access to satellite networking,the network routing and the space networking based on LoRa technology are introduced.2)The multi-access system scheme for centerless network is proposed based on block partition.The idea of block division is used to divide the earth surface into hexagons,then the centerless Ad hoc network is established inside and outside the block by combining the advantages of time division multiple access(TDMA)and frequency division multiple access(FDA).At the same time,this method makes the multi-access network algorithm have consistency when establishing the connection between adjacent six blocks,which solves the contradiction between the large number of satellites and the limited spectrum resources.3)The satellite network layer design is completed based on network static route snapshot technology.Utilizing the network static route snapshot technology to design the network layer can effectively solve the problem of unstable node connection caused by high-speed running of on-orbit satellite.In addition,the satellite network routing table is analyzed and calculated by using SGP4 model and Dijkstra shortest path algorithm to verify the rationality of satellite network layer design.4)The satellite physical layer design is completed based on LoRa technology.Since LoRa has the advantages of strong dynamic adaptability,high receiving sensitivity and long communication distance,it is used to conduct the design of radio frequency circuit and communication transceiver process in physical layer.5)Multiple satellites are used to verify the satellite network layer,data link layer and physical layer.The reliability of receiving and sending data via network is verified in network layer;the effectiveness of the multi-access protocol is verified in data link layer;and the network coverage meets the requirements of block division is verified in physical layer by transmission power test and link margin calculation.Finally,the completed work in the full text is summarized and the further research directions are pointed out.