Waveform Design And Signal Separation Research For Satellite Overlay Communication

Satellite communication is widely used in many scenarios because of its globalization,all-weather,and high reliability.However,satellite communication has security problems,which makes the signals relayed by satellite easy to be detected.The satellite overlay communication technology uses two signals to transmit at the same frequency at the same time,and uses special means to separate the signals at the receiving end,so the communication signal can seek a specific signal as a cover to improve the security of signal transmission.The key issue of the above system are mainly in two aspects.On the one hand,it is to increase the complexity of the non-cooperating party to eliminate the mask signal as much as possible,and on the other hand,to minimize the impact on the transmission of communication signals.Aiming at the requirements of safe transmission and reliable reception of satellite communication systems,this paper designs a safe transmission waveform for satellite overlay communication systems,and analyzes a signal separation scheme for cooperative reception,to promote the engineering application of the above technologies.The main contents are as follows:1.In the satellite overlay communication system,the power imbalance between the mask signal and the communication signal may prompt the non-cooperative party to demodulate and cancel the mask signal.Accordingly,this paper proposes a waveform design scheme for satellite overlay communication,The modulation method of the mask signal adopts the weighted fractional Fourier transform to increase the difficulty of identifying and demodulating the mask signal for non-cooperating parties.The simulation shows that,compared with the traditional method,the modified mask signal effectively improves the security of signal transmission.2.Aiming at the multi-user receiving requirements of satellite overlay communication,this paper designs a signal separation scheme for cooperative reception.After the demodulation and reconstruction of the mask signal is achieved,this paper uses an improved phase-locked loop and an adaptive filter to improve the fitting degree of the reconstructed local signal and the received signal,and reduce the residual of the mask signal in the separated communication signal.poor ingredients.The simulation shows that,compared with the existing separation methods,the bit error rate performance improves.3.In order to verify the feasibility of the engineering application of the scheme proposed in this paper,his paper uses a signal generator to generate signals,and performs hardware-in-the-loop simulation to verify the signal cancellation effect and communication performance.The experimental results show that the signal separation scheme proposed in this paper can realize the separation of the actual mask signal,which lays the foundation for the subsequent realization on the hardware platform.