Single channel blind source separation of co-frequency digital signals via factor graph

To solve the single channel blind source separation(BSS) problem of co-frequency digital modulated mixtures with complex codes,the unified frame of the separation algorithm is given under factor graph.By combining sum-product(SP) algorithm with ECM algorithm organically,a novel code-aided single channel blind source separation algorithm based on factor graph is proposed.The expressions to estimate all the synchronization parameters are derived under maximum likelihood law.The proper factor graph model is established for the mixture with inter-symbol interferences,using the generalized distribution law,and the posteriori probability estimation of the symbols is given.The simulation results show that,the new algorithm can not only gain almost equivalent performance towards the mixture using convolutional codes,but effectively estimate the parameters and sequence of the mixtures using complex codes such as LDPC.