The existing physical layer secret key generation scheme is not sufficiently secure when the eavesdropper keeps close to the legitimate user to get the correlated channel characteristics.To solve the problem

this paper analyzes the secret key bit error rate and proposes a physical layer secret key generation scheme based on signal propagation characteristics.We calculate the large scale fading model which parameters is fitted by the measured sample

in order to get the small scale parameter of received signal strength indication under the effect of multipath fading to quantify into binary secret bit.The experimental results show that compared with the traditional scheme

in the indoor environment

after eavesdropping distance is greater than 0.6 wavelength

the eavesdropper key bit error rate is greater than 0.48.And in the outdoor environment

after the eavesdropping distance is greater than 1 wavelength

the eavesdropper key bit error rate is 0.47. Secure and reliable physical layer secret key generation is achieved.