FTN传输条件下极化码帧间物理层安全结构设计

Wiretap channel is a widely-used model to describe physical layer security and polar code shows potential in wiretap channel model due to its polarization characteristic. A new inter-block encryption security scheme without the need of acquiring signal-to-noise ratio (SNR) is designed for the polar code under faster-than-Nyquist (FTN) transmission condition. With the scrambling module and the channel degradation of the wiretap model, the bits noiseless for the legal receiver but noisy for the eavesdropper are diffused and a one-time-pad secret key can be generated in each block. The physical layer difference of the main channel and the wiretap channel is applied to generate secret key sequence with is decipherable for the legal receiver and undecipherable for the eavesdropper. The secret key sequence is applied for encrypting the next block, achieving inter-block security transmission within secrecy capacity. The simulation result shows that under the circumstance of FTN signaling, when the channel SNR of eavesdropper is fluctuating from that of the main channel, the inter-block secrecy scheme proposed for the polar code can achieve confidential information transmission even when the average channel degradation of the wiretap channel is 0 dB.