Iterative channel decoding for PC-based software radio DVB-T receiver

The previous scheme only modifies the Viterbi decoder input positions where the Reed-Solomon decoder makes sure they are correct. Although it is simple and can get perfect image quality in static channels, it still suffer image quality degradation in mobile channels. Besides that, we propose to change the parameter Q of the metrics of the Viterbi decoder input positions where the Reed-Solomon decoder makes sure they are incorrect. The Q is defined as the norm of channel state information (CSI), Q = |CSI|². We propose to change Q to maximum for the Viterbi decoder input positions where the Reed-Solomon decoder makes sure they are incorrect, so the incorrect paths are unlikely to be selected in the Viterbi algorithm. The field test results in 100 km/h moving speed show that the proposed scheme with Q modification outperforms the previous scheme without Q modification by 0.36 % (7.45->7.09 %) in symbol error rate and noticeable image quality difference.