Four-dimensional rotating constellation de-mapping method based on joint posterior probability

The invention discloses a four-dimensional rotating constellation de-mapping method based on joint posterior probability. A sending send carries out quadrature phase shift keying mapping on an input bit stream to obtain the kth pair of adjacent modulation signals; real parts and imaginary parts of the kth pair of modulation signals are combined and multiplied by a quadrature rotating matrix P to obtain corresponding rotating signals; I/Q component interleaving is carried out on the rotating signals, a receiving end calculates channel coefficients and estimation symbols, I/Q component de-interleaving is carried out, all components and corresponding channel coefficients of the rotating signals are obtained, and the log-likelihood ratio (LLR) of each sent bit is calculated; and the finally-estimated bit information is solved in a hard decision mode. The method has the advantages that information of one symbol is distributed to four dimensions, and the correct demodulation probability of the receiving end can be greatly increased.