Random Pilot Activation and Interpolated Channel Estimation for Physical-Layer Secret Key Generation in Correlated Eavesdropping Channel

In this paper, we propose a novel physical-layer secret key generation (SKG) scheme, which is based on reduced random pilot selection at a legitimate transmitter and channel interpolation at a legitimate receiver. As a result, the proposed scheme is capable of reducing pilot overhead and increasing secret key capacity (SKC) while suppressing information leakage to an eavesdropper in a correlated eavesdropping channel. More specifically, a subset of full pilot sequence is activated based on the legitimate channels at the legitimate transmitter, and the full channel coefficients are estimated from the received pilot symbol subset at the legitimate receiver with the aid of our channel interpolation. Additionally, despite the non-reciprocal channel due to the presence of a Doppler shift and an additive noise, our scheme achieves high SKG reliability in comparison to that without our reduced pilot selection or channel interpolation. We also derive the theoretical SKC for the proposed scheme. Our simulation results demonstrate that the proposed SKG scheme exhibits a higher performance in terms of both the SKC and key disagreement ratio.