A Study on Improving Extended Parity Generation for LDMBSTOFDM In this paper, we studied improvement of extended parity generation for LDMBSTOFDM(Layered Division Multiplexing  Band Segmented Transmission xe2x80x93 Orthogonal Frequency Division Multiplexing). In the proposed scheme for fixed reception, the paritycheck matrix of the LDPC(LowDensity ParityCheck) code whose length is 69120 is extended. After that, the extended parity bits are generated by the extended paritycheck matrix and modulated. These modulated symbols are LDMcombined with the symbols for mobile reception. The performances of the proposed scheme are evaluated by computer simulations under AWGN(Additive White Gaussian Noise). As the results, the required CNR(Carrier to Noise Ratio) of fixed reception can be improved by the proposed scheme.

Constructing QCLDPC codes based on dimension reduction for physical layer security As a recently proposed physical layer security scheme, the twodimensional transmission scheme prevents eavesdropping, but the bit error rate (BER) of the receiver becomes high. A new coding scheme for QuasiCyclic LowDensity ParityCheck (QCLDPC) codes to improve the performance of the receiver is proposed and named as dimension reduction coding. This new scheme constructs the base matrix, which is necessary to obtain the parity check matrix of QCLDPC codes, from the channel coefficient matrix of twodimensional transmission scheme. Then, by analyzing the relationship between the base matrix and the parity check matrix of QCLDPC codes, we find out the conditions that the base matrix must satisfy so that the corresponding parity check matrix has no shortest cycle in Tanner graph. Furthermore, a dimension reduction algorithm is presented to modify the base matrix and obtain parity check matrices with good performance. Finally, simulation results are given and validate the feasibility of this method.