Security-Enhanced AFDM Transmissions Using Integrated Sensing and Communication

With the popularity of high-mobility scenarios in future networks, the issue of security and reliability of their communications is a growing concern. In this paper, a secure transmission scheme for affine frequency division multiplexing(AFDM) systems is proposed, which guides the AFDM modulation parameter design with the information obtained from integrated sensing function and ultimately obtains a differentiated demodulation performance. In order to realize the sensing function based on AFDM, we first establish the input-output relationship of the vectorization of the AFDM system, and propose a radar target echo channel estimation scheme to estimate the channel. The base station sends a set of non-orthgonal multiple access (NOMA) signals with pilot superposition information to the user, and receives radar targets in the discrete affine Fourier transform (DAFT) domain. It enables basestation (BS) to sense the channel delay, doppler shift and channel gain on a fast time axis, make base station and the receiving end have the same modulation and demodulation parameters and maintain good sensing performance even in large Doppler shift scenarios. The base station and the legitimate users have the same confidentiality parameters, effectively preventing eavesdroppers from stealing information. The simulation results verify the effectiveness of our proposed AFDM-based system in high-mobility scenarios and the security of information transmission.