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On MSE Exit Chart Analysis and Real Time DSP Implementation for Iterative (Turbo) Detection

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Abstract

We investigate the use of the mean square error (MSE) transfer characteristics to examine the convergence behaviour of the iterative (turbo) multiuser detector for coded code-division multiple-access (CDMA) systems. Both MSE and mutual information (MI) based extrinsic information transfer (MSE-EXIT and MI-EXIT) chart techniques reveal the same asymptotic and convergence behaviours. An improved low complexity version of the soft interference cancellation MMSE (SIC-MMSE) detection scheme is also proposed for CDMA systems utilizing BPSK modulation. Herein, under fixed-point data representation and computation constraint a real time DSP implementation (using TMS320C6416) is suggested. EXIT charts reveal that fixed-point implementation is feasible at possibly no performance degradation. Based on the measured number of cycles of different constituent sub-functions of the proposed receiver, a data transmission rate of up to 186 Kb/s can be reached for a 5-users load and a processing gain of 7 in an AWGN channel.

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Notes

  1. The term Conjugate is due to the fact that, \( {{\mathbf{r}}_k}\left( {i/i + 1} \right) \) and its conjugate \( {{\mathbf{r}}_k}{\left( {i/i + 1} \right)^* } \)are used.

  2. Notice that this complexity can further be reduced if we assume that the channel is constant over the processed data block so that \( {{\mathbf{\bar{\Lambda }}}_k} = \frac{1}{M}\sum\limits_{i = 1}^M {{{\mathbf{\Lambda }}_k}(i)} \) is used instead of \( {{\mathbf{\Lambda }}_k}(i) \) and hence one matrix inversion is required per data block of M information bits (ergodicity assumption).

  3. Notice that \( {{\mathbf{\Xi }}_{a,k}}(i) \) is a symmetrical matrix which admits real valued eigen values.

References

  1. El Gamal, H., & Hammons, A. R. (2001). Analysis of turbo decoder using the Gaussian approximation. IEEE Transactions on Information Theory, 47(2), 671–686.

    Article  MathSciNet  MATH  Google Scholar 

  2. Bhattad, K., & Narayanan, K. R. (2004). An MSE based transfer chart to analyse iterative decoding schemes. 42nd Allerton Conf. on Communications, Control and Computing, Montelicello, IL, October 2004.

  3. ten Brink, S. (1999). Convergence of iterative decoding. Electronic Letters, 35(13), 1117–1118.

    Google Scholar 

  4. ten Brink, S. (2001). Convergence behavior of iteratively decoded parallel concatenated codes. IEEE Transactions on Communications, 40, 1727–1737.

    Article  Google Scholar 

  5. Shi, Z., & Schlegel, C. (2001). Joint iterative decoding of serially concatenated error control coded CDMA, IEEE Journal on Selected Areas on Communications, 19(6), 1646–1653.

    Google Scholar 

  6. Boutros, J., & Caire, G. (2002). Iterative multiuser joint decoding: unified framework and asymptotic analysis. IEEE Transactions on Information Theory, 48, 1772–1793.

    Article  MathSciNet  MATH  Google Scholar 

  7. Li, K., & Wang, X. (2005). EXIT chart analysis of turbo multiuser detection. IEEE Transactions on Wireless Communications, 4(1), 300–311.

    Article  Google Scholar 

  8. Guo, D., Shamai, S., & Verdu, S. (2005). Mutual information and minimum mean-square error in Gaussian channels. IEEE Transactions on Information Theory, 51(4), 1261–1282.

    Article  MathSciNet  Google Scholar 

  9. Bhattad, K., & Narayanan, K. R. (2005). An MSE based transfer chart to analyse iterative decoding schemes. Available for download at: http://arxiv.org/PS_cache/cs/pdf/0506/0506058.pdf, June 2005.

  10. Ahmed-Ouameur, M., & Massicotte, D. (2007). Real-time DSP and FPGA implementation of Wiener LMS based multipath channel estimation in 3G CDMA systems. Journal of VLSI Signal Processing Systems, 47(3), 259–279.

    Article  Google Scholar 

  11. Wang, X., & Poor, V. (1999). Iterative (Turbo) soft interference cancellation and decoding for coded CDMA, IEEE Transactions on Communications, 47(7), 1047–1061.

    Google Scholar 

  12. Tuchler, M., Koetter, R., & Singer, A. C. (2002). Turbo equalization: principles and new results. IEEE Transactions on Communications, 50(5), 754–767.

    Article  Google Scholar 

  13. Buzzi, S., Lops, M., & Tulino, A. M. (2001). A new family of MMSE receivers for interference suppression in asynchronous multiuser DS/CDMA systems employing BPSK modulation. IEEE Transactions on Communications, 49(1), 154–167.

    Article  MATH  Google Scholar 

  14. Bhashyam, S., & Aazhang, B. (2002). Multiuser channel estimation and tracking for long code CDMA systems. IEEE Transactions on Communications, 50(7), 1081–1090.

    Article  Google Scholar 

  15. Kehtarnavaz, N., & Kim, N. (2005). Real-time digital signal processing based on the TMS320C6000, 1st edition, Elsevier Inc.

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Acknowledgements

The authors would like to thank the Axiocom Inc. and the National Science and Engineering Council of Canada (NSERC) for its financial support. We are grateful the anonymous reviewers critics as well.

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Authors and Affiliations

  1. Laboratory of Signal and System Integration (LSSI), Department of Electrical and Computer Engineering, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, Québec, Canada, G9A 5H7

    Messaoud Ahmed-Ouameur & Daniel Massicotte

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  1. Messaoud Ahmed-Ouameur
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  2. Daniel Massicotte
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Correspondence to Daniel Massicotte.

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Ahmed-Ouameur, M., Massicotte, D. On MSE Exit Chart Analysis and Real Time DSP Implementation for Iterative (Turbo) Detection. J Sign Process Syst 64, 305–317 (2011). https://doi.org/10.1007/s11265-010-0489-2

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  • DOI: https://doi.org/10.1007/s11265-010-0489-2

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