A new constructive approximation in log-map turbo decoder

Authors:
Shahab Asoodeh
Affiliations:
Dept. of Electrical and Computer Engineering, Shahid Beheshti University, Tehran, Iran
Venue:
EHAC'08 Proceedings of the 7th WSEAS International Conference on Electronics, Hardware, Wireless and Optical Communications
Year:
2008

Citing 3
Cited 0

Turbo Coding, Turbo Equalisation and Space-Time Coding for Transmission over Fading Channels

Turbo Coding, Turbo Equalisation and Space-Time Coding for Transmission over Fading Channels
Implementation of parallel and serial concatenated convolutional codes

Implementation of parallel and serial concatenated convolutional codes
An intuitive justification and a simplified implementation of the MAP decoder for convolutional codes

IEEE Journal on Selected Areas in Communications

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Abstract

Although the Log-MAP algorithm has a high capability in correcting errors amongst turbo decoding algorithms, but the existence of ln(ċ) and exp(ċ) functions in this algorithm, decreases the speed and makes its implementation difficult. For solving this problem, new methods for approximating these two complex functions has been suggested. A new method in this area has been proposed in this paper that can estimate the functions with high accuracy and minimum computational complexity. Furthermore in order to prevent overflowing of the amounts of short variables during decoding, a new and simple method about normalizing the amounts of forward and backward metrics has been presented in this paper.