On-line extraction of soft decoding information and applications in VLSI turbo decoding

Zhongfeng Wang, Keshab K. Parhi

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


In this paper, a set of variables which can be easily computed in the course of iterative decoding of turbo decoders named turbo decoding metrics (TDMs) are introduced. TDMs are measured twice per iteration. According to the measured values, a lot of information other than the signal-to-noise ratio (SNR) in the received data, such as how good (or bad) the current decoding block is and how close to the convergence the current decoding is, can be obtained. Detailed discussions are provided regarding why these variables are considered. Based on the measured TDMs after the first iteration, an approximate channel reliability value (denoted as Lc) can be obtained for MAP-based turbo decoders. Simulation results show that there is no performance degradation if approximated Lc values are used instead of using exact values. It is also shown that the adaptive decoding approach employing TDMs is more efficient than all existing methods in terms of hardware and latency. Other applications of TDMs are also pointed out.

Original languageEnglish (US)
Pages (from-to)760-769
Number of pages10
JournalIEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing
Issue number12
StatePublished - Dec 2002

Bibliographical note

Funding Information:
Manuscript received November 2, 2000; revised November 26, 2002. This research was supported by the Defense Advanced Research Project Agency (DARPA) under Grant DA/DABT63-96-C-0050. This paper was recommended by Associate Editor Y. Wang.


  • Adaptive decoding
  • Blind decoding
  • Decoding metrics
  • Error correction code
  • Statistical property
  • Turbo code


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