A Novel Modulation Waveform Design With Reduced PAPR

In recent years,Unmanned Aerial Vehicles(UAVs)have gradually played an irreplaceable role in military electronic countermeasures and other fields by virtue of its small size,high mobility and zero casualties,and its physical layer security issues have become a research hotspot at home and abroad.The traditional anti-interception techniques such as spread spectrum and frequency hopping techniques can no longer be reliably guaranteed with the maturity of targeted deciphering technologies such as signal blind detection.However,the current mainstream antiinterception techniques primarily focus on how to further improve the concealment of the transmission waveform,while ignoring the peak-toaverage power ratio(PAPR)problem it may bring.In this thesis,the design of a new anti-interception modulation waveform with reduced PAPR is investigated from the perspective of orthogonal precoding to mainly address the PAPR problem and information transmission security of highspeed data-link transmission waveform for UAVs.Combining the traditional Zadoff-Chu matrix and digital chaos,this thesis proposes a chaotic anti-intercepted ZCT precoding algorithm with low PAPR,which dynamically generates the characteristic parameters of the traditional ZCT matrix and interleaves the ranks by introducing a onedimensional logistic chaotic sequence,and then constructs a chaotic dynamic ZCT matrix,which can obtain a huge key space while maintaining the characteristics of the original ZCT matrix.Simulation results show that the chaotic ZCT matrix can achieve a significant PAPR reduction and a good ring-set encryption of constellation diagram by precoding baseband modulated symbols.Considering the high computational complexity of the chaotic ZCT matrix encryption system,this thesis futher proposes a pseudo-random orthogonal precoding algorithm(PROPM)with reduced PAPR and low complexity based on a group of perfect sequence,and gives the corresponding low-complexity transceiver model,by which the precoding matrix is constructed as a chaotic encrypted unitary matrix with at most four equal-amplitude non-zero complexes in each row and column.The high sparsity and the unitary characteristics of the matrix ensure that the computational complexity of the transceiver is lower than that of most existing precoding schemes,and using this type of matrix for precoding can generate a new encrypted anti-interception waveform with reduced PAPR.Simulation results show that the PROPM algorithm can tremendously reduce PAPR of the transmitted signal with lower computational complexity,and obtain the same BER performance as existing precoding schemes in AWGN and multipath fading channels.The three-dimensional hyper-chaotic sequence randomly generates three sets of characteristic parameters of the matrix,which greatly improves the dislocation performance of the modulated signal constellation and enhances the security of data transmission while increasing the key space of the system.