Truncation Depth Rule-of-Thumb for Convolutional Codes
- Author
- Moision, Bruce
- Published
- January 2009.
- Physical Description
- 1 electronic document
Online Version
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- Restrictions on Access
- Unclassified, Unlimited, Publicly available.
Free-to-read Unrestricted online access - Summary
- In this innovation, it is shown that a commonly used rule of thumb (that the truncation depth of a convolutional code should be five times the memory length, m, of the code) is accurate only for rate 1/2 codes. In fact, the truncation depth should be 2.5 m/(1 - r), where r is the code rate. The accuracy of this new rule is demonstrated by tabulating the distance properties of a large set of known codes. This new rule was derived by bounding the losses due to truncation as a function of the code rate. With regard to particular codes, a good indicator of the required truncation depth is the path length at which all paths that diverge from a particular path have accumulated the minimum distance of the code. It is shown that the new rule of thumb provides an accurate prediction of this depth for codes of varying rates.
- Other Subject(s)
- Collection
- NASA Technical Reports Server (NTRS) Collection.
- Note
- Document ID: 20090008427.
NPO-45009.
NASA Tech Briefs, January 2009; 32. - Terms of Use and Reproduction
- Copyright, Distribution as joint owner in the copyright.
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