DocumentCode :
1197919
Title :
On the use of partial unit memory codes for woven turbo codes with outer and inner warp
Author :
Fagoonee, L. ; Shavgulidze, S. ; Honary, B.
Author_Institution :
Dept. of Commun. Syst., Univ. of Lancaster, UK
Volume :
152
Issue :
5
fYear :
2005
Firstpage :
593
Lastpage :
597
Abstract :
The encoding, decoding and performance analysis of concatenated partial unit memory (PUM) code structures for capacity approaching performance are investigated. PUM codes are known for their excellent distance properties and lower decoding complexity compared to equivalent multi-memory convolutional codes. Two capacity approaching concatenated structures are considered: turbo codes (TCs) and woven turbo codes (WTCs), both initially proposed with component convolutional codes. TCs consist of a number of parallel concatenated encoders. WTCs were originally proposed with outer warp, that is a number of outer encoders are parallel concatenated to one inner encoder. WTCs are also constructed with inner warp, i.e. one outer encoder is parallel concatenated to a number of inner encoders. An iterative max-log-maximum a posteriori decoding scheme is proposed for decoding PUM codes having multiple-input parallel branches in the trellis. The distance properties and bit error rate performance of the novel concatenated PUM codes are compared with known concatenated convolutional codes. It is observed that PUM structures, both TC and WTC with inner and outer warp, have better distance properties and hence improved performance over their equivalent convolutional counterparts. Performance as close as 1.25 dB from the Shannon limit is obtained for concatenated PUM structures with an interleaver size of only 4800 bits.
Keywords :
communication complexity; concatenated codes; convolutional codes; error statistics; iterative decoding; maximum likelihood decoding; maximum likelihood estimation; trellis codes; turbo codes; PUM code structure; Shannon limit; WTC; bit error rate; equivalent multimemory convolutional code; inner warp codes; iterative MAP decoding scheme; lower decoding complexity; max-log-maximum a posteriori decoding; outer warp codes; parallel concatenated encoder; partial unit memory; trellis code; woven turbo code;
fLanguage :
English
Journal_Title :
Communications, IEE Proceedings-
Publisher :
iet
ISSN :
1350-2425
Type :
jour
DOI :
10.1049/ip-com:20045196
Filename :
1522069
Link To Document :
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