基于可靠度的循环冗余校验算法

Cyclic redundancy check algorithm based on reliability

针对循环冗余校验(CRC)准则在信道条件恶化时可能使译码出现较大迭代次数及错误的问题,提出了基于可靠度的迭代停止算法及重传算法。首先,每次迭代后,计算本次译码中间结果的可靠度,通过判断其是否达到阈值来实现迭代的提前结束;然后,将具有最大可靠度的中间结果保存并作为最终译码结果;最后,每次译码后,通过判断最大可靠度是否低于重传阈值来决定是否重传,通过至多3次传输的译码结果来计算最佳译码结果。仿真结果表明,在信噪比低于1.2 d B时,与CRC准则相比,迭代停止算法能在不增加迭代次数的基础上减少1或2个比特错误,重传算法能进一步减少至少2个比特错误,基于可靠度的算法可以实现更少的误比特数和迭代次数。

Large iterations and errors may be caused by using the Cyclic Redundancy Check （CRC） criterion in decoding when channel condition gets worse. Thus, an iterative stopping algorithm based on reliability and a retransmission algorithm were proposed. First, the reliability of the intermediate result was calculated after each iteration, and it was used to achieve early stop of iteration by reaching a threshold. Second, the intermediate result corresponding to the maximum reliability was saved and used as the final result of decoding. Finally, after each decoding, the maximum reliability was used to determine whether to retransmit by being under a threshold of retransmission or not, and the best result of decoding was calculated by using results of no more than three transmissions. Simulations show that, when signal to noise ratio is less than 1.2 dB, in comparison with the CRC criterion, bit errors can be reduced by one or two on the basis of not increasing iterations by using this stopping algorithm, and bit errors can be further reduced by at least two by using the retransmission algorithm. The algorithm based on reliability can achieve less number of bit errors and iterations.