MEHTOD AND APPARATUS FOR SOFT DEMODULATION FOR QUADRATURE AMPLITUDE MODULATION IN MOBILE TELEVISION SERVICE

摘要

A method and an apparatus for soft demodulation for Quadrature Amplitude Modulation (QAM) in mobile television service are provided. In the method, according to the channel estimation value of each subcarrier of Orthogonal Frequency Division Modulation (OFDM) symbols to be demodulated at present, amplitude decision threshold for each subcarrier of the OFDM symbols to be demodulated is determined, and soft information values of low bits in the constellation diagram corresponding to each subcarrier are calculated by using the amplitude decision threshold for each subcarrier. By using the method of the present invention, the accuracy of signal demodulation can be increased, and with time domain filtering of channel estimation values of OFDM symbols and frequency domain filtering of each subcarrier signal of OFDM symbols, noise is further suppressed, signal noise ratio of soft demodulation signal and decoding capability of the receiving end are improved.