Reduced-complexity iterative decoder for wavelet-coded systems in flat fading channels

This paper presents a quantization scheme for log-likelihood ratios in order to reduce the computational complexity of an iterative decoder recently proposed for wavelet-coded communication systems. In order to reduce the computational effort, the real-valued LLRs of encoded bits are quantized into three levels of reliability, with a threshold that is determined by minimizing the mean squared error between the original LLRs and the quantized ones. As result, a reduced-complexity iterative decoder is obtained. Performance evaluations of this iterative decoder were carried out by computer simulation and show that it is an effective means for reducing the computational load of wavelet-coded systems. Therefore, this new approach for iterative decoding may lead to new alternatives for exploiting the potential of wavelet coding for digital communications over wireless channels.