A Novel Method for FQPSK Soft Information Demodulation
Huang Chong-jiong · Telecommunication Engineering · 2009
For integrating FQPSK (Filtered QPSK) with LDPC codes together to get high power and spectrum efficiency system,the decoding soft information is required.By adopting the method of decoding convolutional codes,the soft demodulation MAP algorithm of FQPSK is obtained. The new method can get the channel soft information efficiently. By combining it with the SPA decoding algorithm of LDPC codes,the good decoding performance is realized. The new method has good performance while the complexity of the receiver is reduced. The theoretical analysis and simulation results have proved that FQPSK modulation system based on LDPC codes improves the efficiency of system power and spectrum due to the new demodulation,and compared with QPSK,the system has little loss of the performance while the total power efficiency has been improved.