Research On Key Generation Method Based On Channel Phase Feature For D2D Group Communication

With the rapid development of wireless communication technologies,the 5^th generation communication is about to be practically utilized.Several new communication technologies could effectively improve the transmission speed of wireless communication and make the network structure more flexible.As one of the key technologies of 5G,D2D communication could achieve a direct communication among several devices.Thus,the burden of the core network is reduced effectively.Moreover,the transmission rate and the frequency utilization are improved.The flexibility,convenience and efficiency of D2D communication has caught much attention of researchers.Because of high transmission speed of 10Gbps,it is very difficult to realize such complex calculation of encryption and decryption in a short time in traditional approach.Fortunately,the key generation method with the characteristics of wireless channel reciprocity does not require an intricate algorithm.The security relies upon the spatial and temporal reciprocity of the channel and the key update could be done within a short time.A large scale deployment of array antennas in 5G communication makes the channel characteristics more obvious and the key extraction more convenient.Currently,the research on D2D communication mainly focused on node discovery and radio resource management,and the security aspects are rarely mentioned.Literatures have proposed some security solutions targeted to the application layer.As dealing with the security issues in the physical layer possesses an advantage,this thesis concentrates on the security challenge in the physical layer.In this thesis,we analyzed the characteristics and security of the D2D group communication,and the key generation methods based on the physical layer.We proposed two methods of group key generation based on the channel phase and the channel phase difference.The main contributions are two folds.1)We studied the method of group key generation based on channel phase and NOMA modulation.When a base station adopts NOMA modulation,a group key generation scheme based on channel phase is proposed.In this scheme,the connection between the base station and the group communication devices is in a star graph,and the group key is extracted with the channel phase characteristic values between all group communication apparatus and the base station.Compared with the traditional encryption and decryption operations,the way of using the channel feature to generate a key effectively reduces the complexity of the algorithm and the load imposed on the core network.Since the channel phase is uniformly distributed,the uniform quantization method could be used in the quantization stage of the channel eigenvalue,which reduces the complexity and time consumption in the quantization process compared with the quantization method used in the received signal strength.In addition,the key generation based on the channel phase could be used while the user equipment is in a relatively stationary state,which reduces the environmental requirements of the key generation based on the physical layer.2)We studied the group key generation with channel features,and proposed the method of group key generation based on channel phase difference.In this scheme,a user device in the group is selected as the central node,and all user devices in this group generate the group key by performing steps such as quantizing and encoding the channel phase characteristics between the center node and the base station.Compared with the first scheme,this scheme lowers the times of channel phase estimates and decreases the error caused by the channel estimation process.The randomness test and the security analysis show that the scheme generates the key usability.By the simulation results,when the SNR is more than 4dB,the key generation rate of the later scheme is higher and the key inconsistency rate is lower.