Hardware implementation issues of turbo decoders

This paper gives a general overview of the implementation aspects of turbo decoders. Although the parallel architecture of the turbo code is emphasized, the serial concatenated convolutional codes for the turbo decoder are discussed too. Considering the general structure of iterative decoders, the main features of the soft input and soft output algorithm, which are the heart of a turbo decoder, are observed. The efficient parallel architectures of turbo decoders are shown which allow high speed implementation. Apart from these, implementation aspects like quantization issues and stopping rules to increase the throughput as well as an evaluation of the various turbo decoders are discussed. Finally, we suggest a number of solutions to overcome the implementation issues as well as the complexities without affecting the high throughput rate. DOI: http://dx.doi.org/10.3329/bjsir.v47i3.13068 Bangladesh J. Sci. Ind. Res. 47(3) , 327-332 2012

[1]  A. Giulietti,et al.  Parallel turbo coding interleavers: avoiding collisions in accesses to storage elements , 2002 .

[2]  Ali Ghrayeb,et al.  An improved SOVA algorithm for turbo codes over AWGN and fading channel , 2004, 2004 IEEE 15th International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE Cat. No.04TH8754).

[3]  Andries P. Hekstra,et al.  An alternative to metric rescaling in Viterbi decoders , 1989, IEEE Trans. Commun..

[4]  Jung-Fu Cheng,et al.  Linearly approximated log-MAP algorithms for turbo decoding , 2000, VTC2000-Spring. 2000 IEEE 51st Vehicular Technology Conference Proceedings (Cat. No.00CH37026).

[5]  Joachim Hagenauer,et al.  A Viterbi algorithm with soft-decision outputs and its applications , 1989, IEEE Global Telecommunications Conference, 1989, and Exhibition. 'Communications Technology for the 1990s and Beyond.

[6]  Alfonso Martinez,et al.  Efficient stopping rule for turbo decoders , 2006 .

[7]  Catherine Douillard,et al.  Iterative Decoding of Concatenated Convolutional Codes: Implementation Issues , 2007, Proceedings of the IEEE.

[8]  Fabrizio Pollara,et al.  Stopping Rules for Turbo Decoders , 2000 .

[9]  P. Glenn Gulak,et al.  Simplified MAP Algorithm Suitable for Implementation of Turbo Decoders , 1998 .