A novel high speed communication system based on the concatenation of RS and QC-LDPC codes

In high speed communication, forward error correcting codes have been successfully implemented to offer error-free transmission with high spectral efficiency. The strong candidate for high speed communication system is Low Density Parity Check (LDPC) code. But LDPC code alone will have unwanted error floor. In order to overcome this, a Reed Solomon (RS) code is concatenated with LDPC code. In this paper, we propose an efficient concatenation of RS and structured Quasi Cyclic (QC)-LDPC codes with reduced complexity. We investigate the performance of various decoding algorithms of QC-LDPC code. Their performances in terms of error and complexity are compared. The convergence speed of various decoding methods of LDPC code are analyzed by using the principle of Density Evolution. The one which is more suitable for hardware implementation in terms of structural complexity and latency is identified. This algorithm is chosen as the QC-LDPC decoding algorithm for concatenation. Our simulation results show an improvement of 3dB in Bit Error Rate with concatenation.