Research On Extraction Technology Of Multi-dimensional Channel Characteristics In Physical Layer Key Generation

Over the past period of time,with the continuous maturity of wireless communications,the contradiction between the increase of the audience and the security of data transmission in the wireless communication scenario has been increasing.The wireless channel of the physical layer has been paid attention to by more scholars due to its unique properties: time-variability,randomness,space-time uniqueness,and unpredictability.The friendly communication user extracts the key from real-time changing wireless channel information as a public random resource pool.It avoids the distribution and management process after the key generation and helps to enhance and supplement the existing security protocol mechanism to large extent.Based on this,this article will start from the perspective of the physical layer and carry out related research work on key generation technology.The main work includes:1)Research work has been carried out on channel state information extraction technology in Time Division Duplexing(TDD)mode.First,analyze the specific scheme of the typical one-way channel detection technology.To solve the problem of low key generation rate when the channel environment changes slowly,channel detection methods such as random disturbance,relay forwarding,and network coding are introduced.At the same time,the theoretical formula of achievable key rate is analyzed to evaluate the performance of the algorithm.Increase the key generation rate by introducing more random variations,such as relay channels,artificial random disturbances,etc.Under given simulation conditions,compared with traditional one-way detection technology,the introduction of random disturbance can bring a certain degree of improvement in the achievable key rate;After the relay is added,since the relay channel can add a new random amount,it can further increase the achievable key rate.2)Research work is carried out on the channel state information extraction technology in Frequency Division Duplexing(FDD)mode.Aiming at the problems of security cannot be guaranteed,and the length of the key extraction process in static or quasi-static environments is limited,asymmetric random disturbance,symmetric random disturbance,relay TDD mode assisted and FDD mode assisted channel detection methods are introduced.Compared with conventional two-way detection,random disturbance and relay assistance can increase the reachable key rate.Compared with asymmetric disturbance,symmetric disturbance avoids the secondary transmission of part of the disturbance signal,and its safety is guaranteed;The achievable key rate depends on the variance of the two random disturbance signals.When the variances are the same,the achievable key rate is equal.The relay TDD auxiliary model only uses the relay channel and ignores the non-reciprocity of the user channel;However,the relay FDD auxiliary model uses both the user channel and the relay channel,and its achievable key rate is better than that of the TDD mode.3)Research on key generation technology based on multi-dimensional channel state information is carried out.It mainly includes preprocessing,multidimensional information quantification and key agreement technology.In the preprocessing technology,the improved singular value decomposition algorithm have relatively better results because of the multi-layer decomposition and only the effective signal part is retained;but the computational complexity is relatively high.Therefore,the use of preprocessing algorithm is comprehensively related to the actual system complexity and preprocessing effect.In the quantization technology of multi-dimensional information,the key generation rate performance of using multi-dimensional information is better than that of using only one-dimensional information;The improved K-means algorithm has the best effect,but the algorithm has an information sharing process that causes the problem of channel resource consumption;The equal probability quantization algorithm has the advantages of simple implementation,no additional consumption of channel resources,and high key randomness.In the negotiation technology,the Cascade negotiation algorithm is suitable for situations where the channel environment is bad and the real-time key requirements are low;The process of error correction code negotiation and improved algorithm implementation is simple,and it is suitable for scenarios where the channel environment is relatively good or the performance is within the acceptable range of the system;Because the interleaving method makes the inconsistent sequence scattered more random,the improved algorithm negotiation performance is better than the original algorithm.4)Detailed analysis and design of the key generation process of the low-orbit satellite system,specifically using two-way channel detection,improved singular value decomposition preprocessing algorithm,two-dimensional channel state information quantization technology and improved error correction Code negotiation algorithm.From the point of view of digital simulation,the proposed overall scheme can meet the final system requirements and obtain the security key.In summary,this article has conducted a detailed study on the key technologies involved in the key generation algorithm based on the physical layer,and proposed corresponding improvements for different technologies to improve the performance of the system.At the same time,relevant design is carried out for the key generation process of the satellite-to-earth system.