计算机工程与应用 ›› 2007, Vol. 43 ›› Issue (7): 129-132.

• 网络、通信与安全 • 上一篇    下一篇

两种LDPC译码算法在OFDM系统应用中的改进

屈兰 谢显中 张德民   

  1. 重庆邮电大学 重庆移动通信重点实验室
  • 收稿日期:2006-07-07 修回日期:1900-01-01 出版日期:2007-03-01 发布日期:2007-03-01
  • 通讯作者: 屈兰

The improvements of two LDPC decoding algorithms as appling in the OFDM systerm

  • Received:2006-07-07 Revised:1900-01-01 Online:2007-03-01 Published:2007-03-01

摘要: 低密度校验码是一种基于稀疏校验矩阵的线性码,此码性能性能接近Shannon 限,并具有简单有效的迭代译码算法。大部分文献提到的LDPC 迭代译码算法均基于BPSK调制下,相对于MQAM/MPSK 调制,BPSK 调制频谱利用率太低。在未来的3G+高速无线通信中,最广泛运用的物理层技术OFDM必然采用频谱利用率较高的多电平调制。因此,如何把LDPC码用于多电平调制下的OFDM 是一个关键。

关键词: LDPC, OFDM, 概率似然比, 对数似然比

Abstract: Low density check code is a kind of line-codes basing on a sparse check Matrix.This kind of channel coding can achieve the near Shannon limit performance.And it has a quite simple decoding algorithm which introduces a iterative decoding method.Large preferences referring to LDPC are basing on binary modulation,such as BPSK.Comparied with multilevel modulation,such as MQAM orMPSK,BPSK using of bandwidth is inefficient.In future 3G+ mobile communications,the extensively adopted technique,OFDM, requires to combine with multilevel modulation. So,How to combine the channel coding,LDPC,with the mult-modulation OFDM is our primary work.

Key words: LDPC, OFDM, Probability-likelihood, Log-likelihood