Research On The Key Technology Of CI/OFDM And TDCS In The Aeronautical Channel

With the rapid development of air transportation, aeronautical communication plays an increasingly important role in the daily life and military applications. The existing aviation communication technology cannot meet the requirements of large capacity, high efficiency, and high reliability of the aeronautical communication system. In this paper, the mature OFDM technology of terrestrial wireless communication system is introduced into the aeronautical communication system. Orthogonal Frequency Division Multiplexing- Transform Domain Communication System(OFDM-TDCS) and Carrier Interferometry- Orthogonal Frequency Division Multiplexing(CI/OFDM) technologies are investigated, which can be well applied to aeronautical communication signaling and data transmission systems.In Chapter 1, the research and application background of aeronautical communications are first introduced. Then, the background and technical characteristics of OFDM technology are overviewed. The potential of OFDM in aeronautical communications is summarized.In Chapter 2, the characteristics of aeronautical fading channel are first summarized. Then, OFDM-TDCS and CI/OFDM technologies are introduced. By analyzing the characteristics of transmitted signal waveform, the advantages are pointed out when these technologies are applied in aeronautical communications.In Chapter 3, the coded OFDM-TDCS system is proposed to apply to the aeronautical communication signaling transmission system. The transmitted signal waveform design and signal detection technologies are described in detail. Extensive simulations under aeronautical fading channels show that the coded OFDM-TDCS system can achieve desirable bit-error-rate performance under very low SNR scenarios. In order to improve the spectral efficiency of OFDM-TDCS system, several the spectral efficient OFDM-TDCS system schemes are compared, and the simulation results show that the coded OFDM-TDCS system with Quadrature Cyclic Code Shift Keying(QCCSK) can achieve twice the spectral efficient at the cost of some bit-error-rate performance. According to the time-variant characteristics of two-path enroute channel model, a signal detection algorithm in time domain is further proposed. The simulation results demonstrate that the proposed algorithm can provide a reliable transmission performance with low computational complexity.In Chapter 4, Non-Contiguous CI/OFDM(NC-CI/OFDM) technology is applied to the aeronautical communication data transmission system. A new CI spreading method, including transmitting signal and receiver algorithm, is proposed for complicated interference environment. In order to improve the performance of data transmission, a pilot symbols design method is proposed based on iterative averaging processing. Simulation results verify that the proposed pilot symbols design method achieves significant performance gain at the expense of some PAPR performance. Finally, through extensive simulations under various aeronautical fading channel scenarios with typical types of jamming, we verify the proposed NC-CI/OFDM system can obtain desirable performance in the aeronautical communication channel.Finally, this dissertation is summarized in Chapter 5. Possible research direction in the future is also discussed.