A Method for Underwater Acoustic Key Detection Based on OFDM Pilot Sequences

The traditional physical layer key generation technology uses channel temporal variation, reciprocity, and spatial decorrelation to realize key distribution and fast update. However, due to the complex, time-varying and time-delayed features, the underwater acoustic channel environment often changes during channel detection, resulting in impaired channel reciprocity. To solve this problem, this paper proposes an orthogonal frequency division multiplexing pilot structure based on the features of underwater acoustic time-varying multipath channel. The structure can complete key detection when channel reciprocity is impaired, promotes the consistency of observation sequences, and reduces the key disagreement rate. The theoretical deduction proves the validity of the proposed method under an underwater acoustic multipath time-varying channel. Also, the simulation results verify the feasibility of the proposed method.