Low-Power Hybrid Turbo Decoding Based on Reverse Calculation

Hye-Mi CHOI  Ji-Hoon KIM  In-Cheol PARK  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E89-A   No.3   pp.782-789
Publication Date: 2006/03/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e89-a.3.782
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: VLSI Design Technology and CAD
Keyword: 
log-MAP algorithm,  low-power design,  Max-log-MAP algorithm,  reverse calculation,  turbo codes,  turbo coding,  turbo decoding,  

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Summary: 
As turbo decoding is a highly memory-intensive algorithm consuming large power, a major issue to be solved in practical implementation is to reduce power consumption. This paper presents an efficient reverse calculation method to lower the power consumption by reducing the number of memory accesses required in turbo decoding. The reverse calculation method is proposed for the Max-log-MAP algorithm, and it is combined with a scaling technique to achieve a new decoding algorithm, called hybrid log-MAP, that results in a similar BER performance to the log-MAP algorithm. For the W-CDMA standard, experimental results show that 80% of memory accesses are reduced through the proposed reverse calculation method. A hybrid log-MAP turbo decoder based on the proposed reverse calculation reduces power consumption and memory size by 34.4% and 39.2%, respectively.