A SOFT DEMODULATING METHOD FOR 16QAM IN COMMUNICATION SYSTEM

摘要

A soft demodulating method for 16-ary QAM(quadrature amplitude modulation) in a communication system can obtain average power of each constellation in 16QAM by estimating receiving power in traffic channels; And then said received intermediate frequency signal can be made carrier wave delamination, and in-phase symbol sequence information I and quadrature symbol sequence information Q can be obtained; Based on the constellation mapping relation between said input binary bits sequence and I, Q branch, different decision segment and corresponding error probability decision curve can be determined; and in different decision segment, decision can be made for obtained in-phase symbol sequence information and quadrature symbol sequence information by using corresponding decision curve, in order to obtain real value soft information sequence; Finally, resulting real value sequence should be input to decoder and made error correction decoding, reception bits sequence corresponding to transmission bits can be decoded. Present invention can combine fully the advantage of hard decision and soft decision, the algorithm is simple, and it is can be realized easily.