Plasma Sheath Non-stationary Channel Estimation And Correction Communication Method

When the hypersonic vehicle flies in or re-enters the atmosphere at the ultra-high sound speed,a �plasma sheath� is created on the surface of the vehicle.The plasma sheath seriously interferes with the reliable transmission of the communication system for tracking,telemetry and command.It may even form a �black barrier� phenomenon.Therefore,a blackout mitigation adaptive communication method in the plasma sheath environment is studied,and the fading effect of the plasma sheath channel on the communication signal is alleviated,which is of great significance for realizing reliable communication of the aircraft.The main contents of this paper are as follows: 1.The plasma sheath channel characteristics,modeling methods and existing channel estimation methods are introduced.Firstly,analyzing the channel characteristics,the electromagnetic wave signal propagation characteristics and the channel modeling methods of the plasma sheath;Secondly,straighten out the basic theory of classical channel estimation techniques;Finally,the plasma sheath channel is summarized to provide an effective plasma sheath channel adaptive communication scheme.2.The dynamic plasma sheath channel has non-stationary and fast time-varying characteristics.The electromagnetic wave signal propagation process is affected by severe parasitic modulation.Moreover,the conventional equalization,automatic gain control and other receiver technologies cannot effectively alleviate the parasitic modulation effects caused by plasma sheath.Aiming at the above problems,this paper proposes a plasma sheath non-stationary channel communication method,which uses short-spreading technique and non-stationary stochastic gradient recursive minimum mean square error(NSGR-MMSE)channel estimation algorithm.The algorithm can accurately estimate the channel response by judging the non-stationary channel state change and adaptively adjusting the algorithm parameters.The system bit error rate performance is significantly improved compared with the traditional method,and the parasitic modulation effect on the measurement and control communication signal can be effectively alleviated in the high dynamic and non-stationary plasma sheath environment.The simulation results show that the plasma sheath non-stationary channel communication method has improved the bit error rate performance and constellation diagram in different channel scenes.It also has low computational complexity and good real-time performance.Compared with adopting a single technology,the method has a performance improvement of 3-4 orders of magnitude in the same signal-to-noise ratio;At the same time,the proposed non-stationary channel estimation algorithm has a 3-5 dB improvement in the BER performance of non-stationary channel scenarios.3.Aiming at the problem that the phase shift of the communication signal is still measured after the non-stationary channel communication method,this paper proposes a non-stationary channel distortion correction communication method based on the non-stationary channel communication method.The idea of the communication method is to utilize the strong correlation between the reflected signal and the transmitted signal.The phase of the reflected signal is extracted,and the phase of the transmitted data is corrected at the transmitting end to further improve the BER performance of the overall communication scheme.Achieve the goal of communication in non-stationary and fast time-varying plasma sheathed channel environments.The simulation results show that the plasma sheath non-stationary channel distortion correction communication method can further improve the performance of the system by about 1-2 dB in different channel scenes compared with the plasma sheath non-stationary channel communication method.In summary,the plasma sheathed channel communication method and the specific communication algorithm proposed in this paper can significantly improve the communication performance in non-stationary fast time-varying sheath channels.In addition,basic communication requirements can be implemented on existing receivers under certain conditions.