Research On Constellation Encryption Scheme Based On TR-OFDM

With the rapid development of wireless communication technology and Internet technology,various applications of wireless communication technology have gradually integrated into our lives,and technologies such as unmanned driving,telemedicine,and industrial Internet have all ushered in vigorous development.At the same time,how to ensure the transmission security of wireless communication has also become crucial.Physical layer security encryption technology,as a supplement and improvement of an upper layer encryption scheme,has broad research prospects and application potential.The combination of Time Reversal(TR)and Orthogonal Frequency Division Multiplexing(OFDM)can reduce the bit error rate of the OFDM system,shorten the channel delay expansion,and improve the security of the OFDM system.This article aims at the physical layer security of the TR-OFDM(Time Reversal-Orthogonal frequency division multiplexing)system,adopts modulation encryption technology,and designs a constellation encryption schemes to ensure the secure transmission of information.First,for the single-antenna scenario,the existing artificial noise solutions cannot guarantee the secure transmission of the TR-OFDM system.The normalized mean value of the channel impulse response is used as the initial value of logistic chaos to generate the key required for encryption,and then the key is used to rotate the constellation points.At the same time,time reversal can focus the encrypted OFDM signals near the legal user,and eliminate the phase shifts caused by the channel to the constellation point,and further ensure the safe transmission of the TR-OFDM system.Finally,the proposed scheme is simulated,which proves that the proposed scheme has better security.Second,a quaternion encryption algorithm is designed for the secure transmission of the TR-OFDM system.First use the channel to generate a quaternion,then the transmitter performs a three-dimensional mapping of the bit sequence,then uses the quaternion to encrypt the three-dimensional constellation points,and then performs I/Q conversion to the three-dimensional constellation points,and then generates OFDM symbols.Send out after time reversal processing.The simulation results show that the encryption algorithm has better to bite error rates performance than the two-dimensional constellation points,and also has a better normalized confidential transmission rate,which can ensure the safe transmission of the TR-OFDM system.