Physical layer key generation for non-codebook transmission mode of 5G TDD system

The design and analysis of traditional physical layer key generation schemes are mostly based on the general communication models. They did not really consider the actual communication scenarios, such as 5G communication. This paper proposed a physical layer key generation scheme for 5G TDD system in non-codebook transmission mode. In our scheme, the gNB uses SRS to complete downlink channel estimation and generates an adapted precoding matrix to assist the downlink signal transmission. Based on existing parameters obtained in the precoding matrix generation, the gNB predicts the signal received by the UE and uses it as a shared source of randomness. The whole process conforms to the 5G protocol. The key extraction can be completed during the interaction between the communication parties, realizing the unity of security and communication.