| The demand of high-speed and broadband wireless transmission of information is increasingly strong, with the rapid development of modern society. Chirp signal attracts more attention gradually, because it has the advantage of broadband, long distance transmission without repeater, being not sensitive to doppler shift, against multi-path fading and spread spectrum. Also, it has become a better choice of achieving data communication among fast-moving civil aircrafts.The grasp of location and current flight states of aircrafts in flight, and the maintenance of effective communication of air-ground and air-air, have become inevitable demands for aircrew work, with the continuous development of the civil aviation industry and rapid change of IT. The construction of air-air communication network will become a new highlight of development in the field of civil aviation. In order to have a better respond to the complicated air emergency, improve the capacity to respond air meteorological conditions and meet the mobile connection needs of passengers. The air-air communication network of civil aviation, based on chirp signal, has the advantages of dynamic, self-organization, multi-hop and broadband network, and so on. It will work safely and efficiently with air-ground VHF data network and aeronautical mobile satellite communication system, and other systems to construct an aeronautical telecommunication network.This thesis mainly studies the key technologies of the physical layer communication based on chirp signal, includes modulation, demodulation, and multiple access technology. Then it proposes the concept of air-air communication network, and investigates the way to build this network. Main work of this thesis is as follows:(1) The performance of chirp signal through different angles is analyzed, by using MATLAB simulation. It includes good autocorrelation, spread spectrum characteristic, strong anti-jamming and anti-noise performance, anti-multipath interference and resistance to doppler shift characteristic of chirp signal.(2) According to the need of achieving high-speed mobile communication among aircrafts, theoretical analysis and simulation of basic principles and performance of four kinds of modulation and demodulation schemes based on chirp signal are made. It includes:①Binary Orthogonal Keying; ②Quadruple Bi-Orthogonal Keying;③Binary Phase Shift Keying-Direct Modulation;④π/4-Differential Quadrature Reference Phase Shift Keying-Direct Modulation. Comparison and analysis through multiple perspectives are made, like anti-noise, anti-doppler effect, anti-multipath interference, and so on.(3) The basic principles of multi-slope multiple access, code division multiple access, multi-carrier-frequency multiple access and time overlap multiple access technique are described. Then MATLAB simulation with Time Overlap Multiple Access technique are made, based on four kinds of modulation and demodulation schemes of chirp signal. The results of simulation, the synchronization mechanism of communication by chirp signal are investigated.(4) The background of constructing air-air communication network is described. Then the concept and characteristic of it are proposed. Finally, the overall program of it and the way of merging with aeronautical telecommunication network has been told in details. |
