A Novel Secret Key Generation Method in OFDM System for Physical Layer Security

In this paper, a novel physical layer key generation method for extracting secret key from mutual channel information in orthogonal frequency division multiplexing (OFDM) systems has been proposed. Firstly, a well-designed data extraction process has been introduced to reduce the redundancy and inconsistency of channel state information (CSI). After that, a new quantization method using gray code is proposed. Furthermore, an associated method is designed to reduce key error rate (KER). With these improvements, higher key generation rate (KGR) can be obtained compared to existing methods. Finally, available secret keys have been generated after information reconciliation and privacy amplification. The proposed method has been analyzed and verified in long term evolution advanced (LTE-A) systems and the generated secret keys have passed randomness test.