Secure Channel Coding Based On QC-LDPC

As one of the latest physical layer security scheme,the two-dimensional transmission scheme guarantees the security of legitimate users in the physical layer.However,while guaranteeing security,the performance of the legitimate receiver in the two-dimensional transmission scheme becomes worse.To solve this problem,a channel coding scheme suitable for two-dimensional transmission is proposed.In this scheme,the base matrix of parity check matrix of QC-LDPC codes is constructed by channel coefficient matrix in two-dimensional transmission scheme.The reasons are as follows: First,the channel coefficients of twodimensional transmission schemes are heterogeneous,unique and real-time.These three properties ensure that the symbols of each transmission are random,only the sender and receiver can get the correct channel coefficients,and also make the eavesdropper who does not use illegal eavesdropping methods unable to get the correct channel coefficients of both the sender and the receiver.These three properties makes it possible to use the channel coefficients of the two-dimensional transmission scheme to construct the base matrix in channel coding to ensure system security;Second,constructing the base matrix with the channel coefficients of the two-dimensional transmission scheme can control the length of the transmitted symbols by controlling the number of antennas,which makes the length of the transmitted symbols more flexible and universal.On this basis,the paper has put forward two schemes.In both schemes,the channel coefficient matrix of two-dimensional transmission scheme obtained by the sender and the receiver is used to construct the base matrix of parity check matrix of QC-LDPC codes.Next,the two schemes operate differently on the basis matrix that have been obtained.The first scheme is based on the condition that there are no four rings in the base matrix,and linear transformation is performed whenever four ring is found,which is more intuitive to operate.In addition,according to the characteristics of two-dimensional transmission scheme,the first scheme sends symbols repeatedly at the transmitter.Accordingly,the receiver compares the received symbols and flips one of them in turn once they are not the same.Under these conditions,if the two symbols received by the receiver are the same,they are not necessarily paired;If they are different,one of them must be wrong.After the signal received by the receiver is judged,the transmission error symbols are corrected by suboptimal solution.The second scheme is to make a deep analysis of the conditions for the generation of base matrix without four ring determine the conditions for the generation of base matrix,and propose a dimension reduction algorithm based on this condition to obtain the base matrix without four ring.