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A Simplified Adaptive Decision Feedback Equalization Technique for π/4-DQPSK Signals
Abstract:We present a simplified equalization technique for a π/4 differential quadrature phase shift keying ( π/4 -DQPSK) modulated signal in a multipath fading environment. The proposed equalizer is realized as a fractionally spaced adaptive decision feedback equalizer (FS-ADFE), employing exponential step-size least mean square (LMS) algorithm as the adaptation technique. The main advantage of the scheme stems from the usage of exponential step-size LMS algorithm in the equalizer, which achieves similar convergence behavior as that of a recursive least squares (RLS) algorithm with significantly reduced computational complexity. To investigate the finite-precision performance of the proposed equalizer along with the π/4 -DQPSK modem, the entire system is evaluated on a 16-bit fixed point digital signal processor (DSP) environment. The proposed scheme is found to be attractive even for those cases where equalization is to be performed within a restricted number of training samples.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1056224Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 5428
 T. S. Rappaport, Wireless Communications: Principles and Practice, 2nd ed. Singapore: Pearson Education, Inc., 2002.
 R. D. Koilpillai, S. Chennakeshu and R. L. Toy, "Low Complexity Equalizers for U.S. Digital Cellular System," in Proc. IEEE VTC, May 1992. pp. 744-747.
 J. Proakis, "Adaptive Equalization for TDMA Digital Mobile Radio," IEEE Trans. Vehicular Tech., vol. 40, no. 2, pp. 313-322, May 1991.
 J. G. Proakis, Digital Communications, 4th ed. NY: McGraw Hill, 2000.
 S. U. H. Qureshi and G. D. Forney, "Performance Properties of a T/2 Equalizer," in Proc. IEEE Globecom, LA, Dec. 1977. pp. 11.1.1-11.1.14.
 R. D. Gitlin and S. B. Weinstein, "Fractionally Spaced Equalization: An Improved Digital Transversal Filter," Bell Syst. Tech. J., vol. 60, pp. 275-296, Feb. 1981.
 Z. Kostic, "Low-Complexity Equalization for ┬╝ 4 -DQPSK signals based on the Method of Projection onto Convex Sets," IEEE Trans. Vehicular Tech., vol. 48, no. 6, pp. 1916-1922, Nov. 1999.
 L. M. Tuan and J. Park, "Novel LMS-Based Exponential Step Size Adaptive Beamforming for Smart Antenna," IEICE Trans. Commun., vol. E85-B, no. 5, pp. 978-981, May 2002.
 Y. Guo and K. Feher, "Performance Evaluation of Differential ┬╝ 4 - DQPSK Systems in a Rayleigh Fading/Delay Spread/CCI/AWGN Environment," in Proc. IEEE VTC, May 1990, pp. 420-424.
 A.H. Aghvami, "Digital Modulation Techniques for Mobile and Personal Communication Systems," Electronics and Communication Engineering J., pp. 125-132, June 1993.
 D. Smalley, Equalization Concepts: A Tutorial, Texas Instruments Application Report, SPRA 140, Oct. 1994.
 M. H. Hayes, Statistical Digital Signal Processing and Modeling, NY: John Wiley & Sons, Inc., 1996.
 K. Feher, "Modems for Emerging Digital Cellular-Mobile Radio System," IEEE Trans. Vehicular Tech., vol. 40, no. 2, pp. 355-365, May 1991.
 A. Narasimhan, S. Chennakeshu and J. B. Anderson, "Decision Feedback Equalization For Digital Cellular Radio," in Proc. IEEE VTC, May 1990, pp. 662-667.
 K. Gentile, "The Care and Feeding of Digital, Pulse- Shaping Filters," RF Mixed Signal, April 2002, http://www.rfdesign.com/ar/radio care feeding digital/.
 Analog Devices, ADSP-2100 Family User-s Manual, Third edition, Sept. 1995.
 R. Steele, ed., Mobile Radio Communications. IEEE Press, 1994.