Channel level crossing-based security for communications over fading channels

Several key exchange methods for wireless channels have been proposed in the literature. They are referred to as physical-layer security techniques and are usually based on the channel´s fading characteristics and the principle of channel reciprocity. In this study, the authors present key exchange algorithms for wireless fading channels whose operation is based on channel estimation. Specifically, the authors present a complete key exchange scheme that includes channel sampling, thresholding and error reconciliation. Two error reconciliation methods are proposed. The first one is based on neural networks and the second one is based on linear block coding. Simulations of the proposed methods´ performances and levels of security are presented and conclusions are drawn regarding their overall utility.