计算机工程与应用 ›› 2008, Vol. 44 ›› Issue (6): 39-41.

• 学术探讨 • 上一篇    下一篇

不等长信源的符号约束MAP联合译码算法

周丹丹,邹 艳,陆佩忠   

  1. 复旦大学 计算机科学与工程系,上海 200433
  • 收稿日期:2007-09-11 修回日期:2007-12-10 出版日期:2008-02-21 发布日期:2008-02-21
  • 通讯作者: 周丹丹

Symbol-constrained joint source-channel MAP decoding of VLCs

ZHOU Dan-dan,ZOU Yan,LU Pei-zhong   

  1. Department of Computer Science and Engineering,Fudan University,Shanghai 200433,China
  • Received:2007-09-11 Revised:2007-12-10 Online:2008-02-21 Published:2008-02-21
  • Contact: ZHOU Dan-dan

摘要: 由于不等长编码信源(VLCs)所固有的易于误码扩散的弱点,传统的纠错编码并不能高效地解决其差错控制问题。提出了一种新的针对不等长编码信源的符号约束MAP联合译码算法,利用VLCs双树信源的构造方法,有效地抑制了VLCs的错误扩散;同时,通过将“符号约束”的思想应用于最大后验概率(MAP)译码算法,不仅充分利用了信源先验信息,而且极大地降低了误符号率。实验结果表明,在误符号率为1%时,对于在高斯加性白噪声(AWGN)信道传输情况下的JPEG信源,提出的算法比传统的“比特约束”MAP译码算法有将近0.8 dB的性能增益。

Abstract: Since Variable-Length Codes(VLCs) are inherently vulnerable to channel errors,traditional error-correcting codes are unable to solve the propagation-error problem efficiently.A new symbol-constrained joint source-channel decoding algorithm for VLCs is presented.By constructing double-tree VLCs sources,the propagation-error problem is evidently alleviated.Meanwhile,by applying symbol-constrained method to MAP algorithm,not only the a priori probability of VLCs sources is efficiently utilized,but also the Symbol Error Rate(SER) is reduced enormously.Compared with traditionally bit-constrained MAP algorithm,simulation results demonstrate that for JPEG source over AWGN channels,the gain in SNR of the method is around 0.8dB when SER reaches 1%.