Improved LDPC Algorithm Based on 16QAM Modulation System
Sun Shaoshuai · Video Engineering · 2012
In this paper,QAM Modulation system is analyzed and a reduced state Soft Input Soft Output(SISO) posteriori probability algorithm is proposed.Based on the sum-product algorithm,it has the more general form compared with other reduced state SISO algorithms.The proposed algorithm use the Euclidean distance between points to calculate bit likelihood values in the demodulator.Then the likelihood value will be entered into the soft-input decoder,thus leads to the computation complexity reduction.Analysis and simulation result show that the proposed scheme can effectively use the soft-output of QAM demodulation,and can get 0.25 dB gain in Gaussian channel compare to the original scheme.