Abstract:

A key generation scheme based on precoding and cooperation matrix (PCM-SKG) is proposed to address the issues of poor randomness of physical layer keys and vulnerability to eavesdropping in a quasi-static environment. First, the precoding matrix P is obtained via singular value decomposition (SVD) of the channel state information. Then, the cooperative matrix U is derived via orthogonal triangular (QR) decomposition of the precoded channel information. Finally, the composite channel information HPU, is utilized to quantify the secret key. Simulation results show that the approximate key entropy of the PCM-SKG increases nearly two times compared to traditional schemes, while the sliding average step improves key consistency by approximately 8 dB. In minimum mean square error (MMSE) estimation, the key mismatch rate of this scheme is close to 10^-4 at 15 dB, with the communication error rate approaching optimal system performance. The PCM-SKG features low complexity and minimal interactive information, requiring no additional channels or devices for information transmission. By leveraging the diversity of the precoding and cooperative matrices, it achieves a key generation random source that is correlated with and variable to the channel.

Key words: wireless communication, physical layer security, quasi-static channel, key generation, multiple-input multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM)