Advances in Radio Science www.adv-radio-sci.net 1684-9965 1684-9973 7 Kleinheubacher Berichte 2008 2009 10.5194/ars-7-139-2009 http://www.adv-radio-sci.net/7/139/2009/ http://www.adv-radio-sci.net/7/139/2009/ars-7-139-2009.html http://www.adv-radio-sci.net/7/139/2009/ars-7-139-2009.pdf 139 144 2009-05-18 Analysis of iteration control for turbo decoders in turbo synchronization applications T. Lehnigk-Emden lehnigk@eit.uni-kl.de U. Wasenmüller C. Gimmler N. Wehn Microelectronic Systems Design Research Group, University of Kaiserslautern, Erwin-Schroedinger Str., 67663 Kaiserslautern, Germany Wireless data transmission results in frequency and phase offsets of the signal in the receiver. In addition, the received symbols are corrupted by noise. Therefore, synchronization and channel coding are vital parts of each receiver in digital communication systems. By combining the phase and frequency synchronization with an advanced iterative channel decoder (inner loop) e.g. turbo codes in an iterative way (outer loop), the communications performance can be further increased. This principle is referred to as turbo synchronization. The energy consumption and the peak throughput of the system depend on the number of iterations for both loops. An advanced iteration control can decrease the mean number of needed iterations by detecting correctly decoded blocks. This leads to a dramatic energy saving or to an increase of throughput. In this paper we present a new stopping criterion for decodable blocks for turbo decoding in interrelation with turbo synchronization. Furthermore the implementation complexity of the turbo decoder is shown on a Xilinx FPGA. Alles, M., Lehnigk-Emden, T., Wasenmüller, U., and Wehn, N.: Implementation Issues of Turbo Synchronization with Duo-Binary Trubo Decoding, in: Proc. 19th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) 2007, Athens, Greece, 2007. Berrou, C.: The Ten-Year-Old Turbo Codes are Entering into Service, IEEE Communications Magazine, 41, 110–116, 2003. Berrou, C., Glavieux, A., and Thitimajshima, P.: Near Shannon Limit Error-Correcting Coding and Decoding: Turbo-Codes, in: Proc. 1993 International Conference on Communications (ICC '93), pp. 1064–1070, Geneva, Switzerland, 1993. Godtmann, S., Pollok, A., Hadaschik, N., Steinert, W., Ascheid, G., and Meyr, H.: Joint Iterative Synchronization and Decoding Assisted by Pilot Symbols, in: IST Mobile & Wireless Communications Summit, Myconos, Greece, 2006. Hagenauer, J., Offer, E., and Papke, L.: Iterative Decoding of Binary Block and Convolutional Codes, IEEE Transactions on Information Theory, 42, 429–445, 1996. Matache, A., Dolinar, S., and Pollara, F.: Stopping Rules for Turbo Decoders, TMO Progress Report 42–142, http://tda.jpl.nasa.gov/progress_report/, Jet Propulsion Laboratory, Pasadena, California, 2000. May, M., Neeb, C., and Wehn, N.: Evaluation of High Throughput Turbo-Decoder Architectures, in: IEEE International Symposium on Circuits and Systems (ISCAS), New Orleans, USA, 2007. Mengali, U. and D'Andrea, A.: Synchronization Techniques for Digital Receivers, Plenum Publishing Corporation, New York, 1997. Meyr, H., Moeneclaey, M., and Fechtel, S A.: Digital Communication Receivers, John Wiley & Sons Inc, 1998. Robertson, P., Villebrun, E., and Hoeher, P.: A Comparison of Optimal and Sub-Optimal MAP decoding Algorithms Operating in the Log-Domain, in: Proc. 1995 International Conference on Communications (ICC '95), pp. 1009–1013, Seattle, Washington, USA, 1995. Robertson, P., Hoeher, P., and Villebrun, E.: Optimal and Sub-Optimal Maximum a Posteriori Algorithms Suitable for Turbo Decoding, European Transactions on Telecommunications (ETT), 8, 119–125, 1997. Shao, R Y., Lin, S., and Fossorier, M. C P.: Two Simple Stopping Criteria for Turbo Decoding, IEEE Transactions on Communications, 47, 1117–1120, 1999. Thul, M J., Vogt, T., Gilbert, F., and Wehn, N.: Evaluation of Algorithm Optimizations for Low-Power Turbo-Decoder Implementations, in: Proc. 2002 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '02), pp. 3101–3104, Orlando, Florida, USA, 2002. Worm, A., Hoeher, P., and Wehn, N.: Turbo-Decoding without SNR Estimation, IEEE Communications Letters, 4, 193–195, 2000. Wu, Y., Woerner, B D., and Ebel, W J.: A Simple Stopping Criterion for Turbo Decoding, IEEE Communications Letters, 4, 258–260, 2000.