Secrecy Rate Comparison of Key-based Encrypted Data Transmission and Keyless Secure Transmission

This paper compares the secrecy rate of two general PHY security approaches of keyless secure transmission (ST) and key-based encrypted data transmission (EDT) in a multiple-input single-output, single eavesdropper (MISOSE) system. Specifically, closed-form approximations of the secrecy rate for both schemes are derived for the same coherence interval and under uncertain eavesdropper location. Our results highlight that the secrecy rate of ST is highly dependent on the propagation distance between the transmitter and the eavesdropper, whilst EDT is more impacted by the coherence interval and transmit power. Numerical simulations based on the IMT-2020 channel model are presented to support our analytical results. Our results clearly highlight different regions where ST or EDT can achieve a higher secrecy rate based on the eavesdropper location relative to the transmitter and receiver in an 11 m × 5 m area.