Ldpc In Lte And 4 G Channel - Cofdm System Modeling Method And Performance Study

The LDPC-COFDM system which is combined low density parity check (LDPC) code and OFDM technology is one of the most attractive transport solutions and it has become a hotspot of mobile communication technologies researches currently. The past of LDPC-COFDM system researches mostly based on traditional mathematical statistical channel models, which can’t truthfully reflect the LDPC-COFDM system performance in the LTE or4G communication channel which has a qualitative change by MIMO technology. Therefore, an in-depth study of LDPC-COFDM system performance and optimization solution in the4G channel environment has important theoretical significance and practical value.Firstly, according to the LDPC codes and OFDM theoretical knowledge, we derived the mathematical model of LDPC-COFDM system based on the channel transmission model. Secondly, according to the LTE and4G mobile communication standards, we analyzed the environmental characteristics and established a MIMO multipath channel model by the relevant-matrix channel simulation methods, to provide a simulation of the realistic channel environment for the study and analysis of the LDPC-COFDM system. Thirdly, we proposed the LDPC-STBC united BP decoding algorithm based on orthogonal space-time coding (STC). The algorithm could not only greatly enhance the decoding accuracy and decoding speed, but also greatly reduce the system hardware and software on the receiver requirements. Finally, based on these works, we simulated and analyzed the LDPC-COFDM system performance under different system parameters and different channel conditions.The simulation analysis showed that the LDPC-COFDM systems could not only flexibly dominate variety of code length and code rate for fast encoding and decoding, but also support the high-order modulation of64QAM or256QAM and so on. The LDPC-COFDM system showed excellent anti-interference capability whether in the SISO multipath channel or the MIMO multipath channel, so it is very appropriate for being used in the4G communication environment. According to the research and analysis conclusions, we provided the LDPC-COFDM system parameters configuration guidelines and practical advice for practical application.