Research On Key Techniques For Multi-antenna Aircraft Communication Systems

In the aircraft communication systems,different waveform schemes need to satisfy different transmission scenes.Multi-antenna orthogonal frequency division multiplexing(OFDM)technology with high bandwidth efficiency and anti-fading ability and continuous phase modulation(CPM)with constant envelope,excellent bandwidth efficiency and power efficiency are very attractive waveform technologies in aircraft systems.Space-Frequency Block Coding-Orthogonal Frequency Division Multiplexing(SFBC-OFDM)system performs coding in frequency domain,it is suitable for time-varying channels and has strong anti-Doppler frequency shift ability,and its waveform scheme to different transmission scenarios needs to be optimized.MIMO-CPM system has high complexity,and it can be further optimized by using simplified detector based on Laurent decomposition of CPM signal.Therefore,in order to improve the practicability and efficiency of the multi-antenna aircraft communication system,this paper studies the key technologies of the multi-antenna aircraft communication system.Firstly,the basic modulation principles of OFDM and CPM systems are introduced,including the basic structure and basic signal model of OFDM transmission system.The signal models of MSK and SOQPSK are also considered,and their phase transfer characteristics are given.Secondly,as the basis of ternary decomposition of CPM signal,the Laurent decomposition principle of binary CPM signals is explained in detail.Then,the design scheme of SFBC-OFDM transmission system is given,the SFBC and soft-decision information under high-order modulation are studied,and the design scheme of multi-subcarrier in multipath channel is simulated.Then,the MIMO-MSK communication system is studied.The intrafix symbols which force the phase to zero are added at the transmitter to keep the phase continuity and Laurent decomposition is carried out to the transmitted.The detection is simplified at the receiver and the designed waveform scheme is simulated and analyzed in flat fading channel.Simulation results show that the simplified algorithm based on PAM decomposition can reduce the complexity of receiver compared with the traditional maximum likelihood sequence detection algorithm,and the performance loss is very small.Finally,on the basis of PAM decomposition of binary CPM signal,PAM decomposition of ternary CPM signal based on double binary coding is studied,and the PAM approximations of MIL-STD SOQPSK and SOQPSK-TG are carried out by using the decomposition method proposed by Perrins-Rice(PRD)and double binary decomposition(DBD)respectively,and the simplified detection methods corresponding to these two decomposition methods are simulated and analyzed in single-antenna and multi-antenna scenarios.Simulation results show that the performance of feedback decision detection proposed in this paper is better than that of traditional linear detection,and the bit error performance of Viterbi algorithm based on DBD is obviously improved compared with Viterbi based on PRD.