Research On The Modulation Recognition Of The Digital Communication Signals In The Aeronautical Communication

The modulation recognition technique between communication signals is a keyone of the field of signal analysis, which has important applications in military andcivilian. Aeronautical communication is an important branch of the wirelesscommunication, so the recognition research of the digital modulation signals in theaeronautical communication is more important. In this paper the modulationrecognition problems of the star Multiple Quadrature Amplitude Modulation (MQAM)signals and Unitary Space Time Modulation (USTM) signals in the aeronauticalcommunication are studied. High Order Statistics (HOS) algorithm and AverageLikelihood Ratio Test (ALRT) algorithm based on hypothesis testing are used torecognize these signals in the aeronautical communication, and then, the simulationand analysis of these algorithms are given. The main research contents include thefollowing three aspects:1. The communication mechanism and system characteristics of the aeronauticalcommunication system are summarized, its system characteristics consist ofmultipath characteristic, multi-band, large spatial dynamic range, Doppler frequencyshift and so on. Based on these characteristics, the time-varying aeronautical channelmodels are built from the perspectives of parking scenario, taxi scenario, takeoff andarrival scenario and en-route scenario and so on, which helps to carry out research ofthe subsequent signal modulation recognition.2. The modulation recognition of the star MQAM signals is studied in theaeronautical communication. Firstly, the high order cumulants characteristics ofMQAM signals are analyzed, and then the feature recognition algorithm constitutedby the high order cumulants is proposed. The different assumptions are given for therecognized MQAM signals, and then the signal transmission characteristics in theaeronautical communication system are considered, so the ALRT algorithm based onhypothesis testing is proposed. And the receive diversity technique is used to optimizethe two algorithms. Finally, the simulation and analysis of these algorithms are given, the results show that the two algorithms and these optimized algorithms can meet therecognition requirements of MQAM signals in the aeronautical communication,especially, the recognition performance of the optimized algorithms is better.3. The modulation recognition of USTM signals is studied in the MIMOaeronautical communication system. Firstly, the constellation of USTM signal isdesigned and analyzed, at the same time, it is expressed with a specific mathematicalformula. Then, the high order statistics of USTM signals are analyzed, and the highorder statistic algorithm is proposed, this algorithm is used to recognize the USTMsignal from the mixed MQAM signals. The composite assumption is put forward forthe mixed-signal containing USTM signals, and then the USTM signal transmissioncharacteristics in the MIMO aeronautical communication system are considered,ALRT algorithm is proposed in order to recognize USTM signal from MQAM signals.At last, the two algorithms are simulated and analyzed based on the aeronauticalchannel models, the simulation results show that the two algorithms can effectivelyrecognize USTM signal from MQAM signals in the aeronautical communication, therecognition performance ofALRT algorithm is better.