Abstract: To address the issue of low randomness and vulnerability to eavesdropping in physical layer keys under quasi-static environments, this paper presents a key generation scheme based on precoding and cooperation matrix (PCM-SKG). The scheme uses singular value decomposition (SVD) to obtain the precoding matrix P from the channel state information. It then performs QR decomposition on the precoded channel information to get the cooperative matrix U. 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 scheme increases nearly three times compared to traditional schemes, while the sliding average step improves key consistency by about 8dB. In MMSE estimation, the scheme achieves a key mismatch rate close to 10-4 at 15dB, with the communication error rate approaching optimal system performance. The PCM-SKG scheme 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 generates random sources for key generation that are channel-dependent and variable.

Key words: Physical Layer Security, Quasi-Static Channel, Multiple Input Multiple Output - Orthogonal Frequency Division Multiplexing(MIMO-OFDM)