Arising needs for extremely simple encoder motivate investigations on distributed video coding (DVC). The Wyner-Ziv coding, one of the representative DVC schemes, reconstructs video by correcting noise on side information using channel code. Therefore, its coding performance decisively depends on the amount of noise in the side information. However it is hard for a decoder to generate good side information, especially in case that frames are less correlated., Large amount of parity bits certainly helps the decoder to correct noise but it only comes with low compression ratio. In this paper, we propose a method to enhance the quality of the side information, with incrementally transmitted parity bits from encoder. Results of our experiments have verified average PSNR gain up to 0.8dB.