Method and system for determining authentication threshold of physical layer

The invention discloses a method and system for determining an authentication threshold of a physical layer, and relates to the technical field of information security. The method comprises that S1) in a first time slot, a valid sender A sends a first data frame to a valid receiver B, and the first data frame is authenticated in the upper layer; S2) a physical-layer authentication 'fingerprint' of the sender A is extracted, and stored in a memory of the valid receiver B; S3) an initial threshold is selected; S4) in a next time slot, a sender X sends a second data frame to the valid receiver B, a physical-layer authentication 'fingerprint' of the sender X is extracted; S5) an authentication 'fingerprint' sample of the physical layer is set; S6) the 'fingerprint' sample and examination statistics of the 'fingerprint' of the present data frame are extracted; S7) a present state is observed, and a next threshold is selected according to a greedy algorithm; and S8) the magnitude of examination statistics is compar