Physical layer security communication for IoT-aided intelligent transport systems: An approach in WFRFT signal domain

The security and reliability of communication systems are crucial for Intelligent Transport Systems (ITS), ensuring user data privacy and the transportation network's stable operation. To address challenges where certain Vehicle User Equipment (VUE) cannot establish stable message exchange with the Base Station (BS), we employ Internet of Things (IoT) nodes to assist in communication setup. Specifically, we propose a weighted fractional Fourier transform (WFRFT)-based two-way relay physical layer security (PLS) communication scheme in the signal domain for IoT-aided ITS. The BS and VUE encode confidential messages into WFRFT signals with private transform orders and perfectly decode the received signal in the specific signal domain. However, in the decoding results at the eavesdropper, not only is the energy of information-bearing signals reduced, but the lost energy also transforms into inter-component interference, further degrading the quality of its received signal. The security gains stem from the mismatched signal domain of the eavesdropper and do not require additional transmit power. Moreover, the security performance is detailed, and the secrecy rate in a time-varying channel is derived. Finally, numerical results validate the theoretical analysis and demonstrate the performance of the proposed scheme.