A Weighted Belief Propagation Decoding Algorithm of LDPC Codes for Fast Convergence and Early Stopping

一種可使LDPC碼快速收斂及早期停止之權重信任傳播解碼演算法

陳作舟(Tso-Cho Chen)

《中華科技大學學報》 52期 (2012/07) Pp. 19-31

https://doi.org/10.7095/JCUST.201207.0019

摘要

本文乃針對低密度奇偶檢查碼提出可加速收斂及減少疊代次數之權重信任傳播解碼演算法。我們所提出的早期停止準則乃是基於從解碼器輸出中所獲得的平均權重可靠度量測值，使得在解碼過程中能盡早偵測出無法解碼的訊息方塊。本文更進一步提出調適性權重疊代方法，用以增進信任解碼演算法的收斂速度，也因而增進改錯性能。隨著解碼疊代而演進的調適性權重疊代因子乃依據解碼器前後兩次解碼器輸出之事後機率分佈的相對熵來決定。模擬結果顯示所提出的演算法與傳統的信任解碼演算法比較，在較中低的E（下標 b）／N（下標 0）值，平均可獲得0.2-0.4 dB的解碼增益，並可減少50%-85%的疊代次數。

關鍵字

低密度奇偶檢查碼 ； 權重信任傳播解碼演算法 ； 早期停止準則 ； 調適性權重疊代方法

並列摘要

A weighted belief propagation decoding algorithm for low-density parity-check decoding is proposed to accelerate the convergence of decoding and reduce the number of decoding iterations. We propose an early stopping criterion which is based on the average weighted reliability measure of the hard output of decoder to detect undecodable blocks in an early stage of the decoding process. In addition, an adaptive weighted iteration scheme is proposed to increase the convergence speed of belief propagation (BP) decoding and therefore improve the error performance. The evolution of the adaptive weighting factor with the number of decoding iterations is based on the relative entropy between two consecutive ”a posteriori” probabilities distribution at decoder output. Simulation results show that the proposed algorithm can achieve about 0.2-0.4 dB coding gain improvement on average while reducing up to about 50%-85% iterations for decoding at low to medium E(subscript b)/ N(subscript 0) , compared with the conventional BP based algorithms.

並列關鍵字

Low-density parity-check code ； weighted belief propagation decoding algorithm ； early stopping criterion ； adaptive weighted iteration scheme