Study On Key Techonologies Of Networking And Transmission In Transoceanic Civil Aeronautical Communication

Transoceanic civil aeronautical communication network(TCACN) is an aeronautical communication network that consists of civil airplanes, satellite, ground stations and the communication links between them whencivil airplanesare in-flight of transoceanic routes. Due to the high cost, the long delay and limited capacity of satellite-based networks, and the limited coverage of ground-based networks, networking an ad hoc networks through civil airplanes is hopefully to become an important make-up of the TCACN, which is mainly based on satellite-based networks and ground-based networks, to provide information transmission and exchange for civil aircrafts in transoceanic flights. Since the satellite-based networks and the ground-based networks have been mature, implemented and in-use, civil aeronautical ad hoc networks(CAANET) is still under research. The media access control(MAC) algorithm and the routing algorithm, which are the key of networking in CAANET, become the key of networking in TCACN.The thesis unites the project “Research on networking and key technologies of transoceanic civil aeronautical mobile broadband communication networks”, which is sponsored by the National Natural Science Foundation of China, aims at the hard problem of networking in CAANET with characteristics of long span, high dynamic topology and long distance between nodes, designs stable, reliable and efficient media access and routing algorithms to achieve the efficient networking of high-dynamic and long-distance nodes; aims at the problem of performance degradation in TCACN caused by packet disorder and the heterogeneity of links and so on, researches TCP congestion control algorithms to achieve efficient transmission. The Main contributions and achievements are:①Aiming at the multi-hop performance degradation problem ofthe long span communication, and the hard application of traditional MANET directional media access algorithm caused by the large propagation delayin CAANET, analyzes the delay performance of the directional neighbor discovery and the performance of the classical time slot scheduling algorithm, proposes a single beam directional antenna MAC protocol(DAMAC) and a multi beam directional antenna MAC protocol(MBAMAC) for CAANET. DAMAC improves the directional neighbor scheme to reduce the discovery delay using the number of neighbors in the reverse beam; provides a single way transmission mode to reduce the transmission delay of burst traffic. MBAMAC employs asymmetric link and traffic-based slot allocation strategy,through inter-links slot scheduling within the node to meet the transmission demand of different links; through adjusting the ratio of transmitting slots and receiving slots inter-nodes to ensure the balance of relay-traffic and the traffic of the node, to reduce the queuing delay and packet loss rate when the traffic load increases, and increase the utilization of the resource when the traffic of the node decreases.Simulation results show that DAMAC and MBAMAC both improves the average transmission rate between node and base station, and reduces the average neighbor discovery time and the average number of hops between node and base station.②In the research of the routing algorithm of TCACN, aiming at the deficiencythat MRPPS has only one reverse path which is easy getting congestion, has not considered satellite access and has high routing overhead,a multi-path routing protocol(MRTAN) for TCACNis proposed. MRTAN adopts an inverse multi-path establishing method which is triggered by relay node and conducted through registration of destination node to reduce the congestion probability of inverse path; employs ADS-B in avoiding periodic transmission of neighbor maintenance message to reduce routing overhead; adopts an adaptive route selection scheme which is based on link and load to realize the smooth handover of satellite path and reduce the transmission delay of burst traffic. The simulation results show that, MRTAN achieves higher network throughput and packet delivery ratio, lower transmission delay and routing overhead than MRPPS. ③Aiming at the problem of performance degradation thatcaused by packet disorder and the heterogeneity of links in TCACN, proposes an efficient TCP congestion control algorithm, INVS.INVS employs a convex window growth function based on exponential function to improve the bandwidth utilization in high BDP network; introduces an adaptive growth factor in the window growth function to match the window growth rate with the link bandwidth and delay; introduces bandwidth estimation in slow start algorithm to improve its performance; uses packet-loss differentiation and back-off strategy which is based onthe routeloadshare flag and the adaptive queue threshold to avoid performance degradation of TCP transmission caused by packet disorder and the wireless link loss.The simulation results show that compared to CUBIC, ATCP and so on,INVS improves TCP transmission performance in the TCACN.