Discrete Polyphase Matched Filtering-based Soft Timing Estimation for Mobile Wireless Systems

Authors: Thomas O. Olwal, Michael A. van Wyk, Barend J. van Wyk

Abstract:

In this paper we present a soft timing phase estimation (STPE) method for wireless mobile receivers operating in low signal to noise ratios (SNRs). Discrete Polyphase Matched (DPM) filters, a Log-maximum a posterior probability (MAP) and/or a Soft-output Viterbi algorithm (SOVA) are combined to derive a new timing recovery (TR) scheme. We apply this scheme to wireless cellular communication system model that comprises of a raised cosine filter (RCF), a bit-interleaved turbo-coded multi-level modulation (BITMM) scheme and the channel is assumed to be memory-less. Furthermore, no clock signals are transmitted to the receiver contrary to the classical data aided (DA) models. This new model ensures that both the bandwidth and power of the communication system is conserved. However, the computational complexity of ideal turbo synchronization is increased by 50%. Several simulation tests on bit error rate (BER) and block error rate (BLER) versus low SNR reveal that the proposed iterative soft timing recovery (ISTR) scheme outperforms the conventional schemes.

Keywords: discrete polyphase matched filters, maximum likelihood estimators, soft timing phase estimation, wireless mobile systems.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1330425

References:

[1] A. Shanmugam and A. R. Abdul Rajak, "Optimal design of forward error correcting codes for wireless communication", www.academicjournal.com, vol. 14, 2005.
[2] CISCO, "Cisco mobile exchange solution guide: Overview of GSM, GPRS, and UMTS", www.cisco.com , 2002.
[3] M. Sellathurai and S. Haykin, "Turbo-Blast for wireless communications: theory and experiments," IEEE Trans. Sig. Proc.., vol. 50, no. 10, pp. 2538-2546, 2002
[4] C. Herzet, V. Ramon, L. Vandendorpe, "Iterative soft-decision directed timing estimation for turbo receivers," IEEE 9th Symposium on Commun., and Vehicular Technology, pp. 97-101, 2003
[5] N. Noels, V. Lottici, A. Dejonghe, H. Steendam, M. Moeneclaey, M. Luise, L. Vandendorpe, "A theoretical framework for soft-informationbased synchronization in iterative(turbo) receivers," EURASIP J. Wireless Commun., and Network., vol. 2, pp. 177-129, 2005.
[6] K. H. Mueller and M. Muller, "Timing recovery in digital synchronous data receivers," IEEE Trans. Commun., vol. Com-24, pp. 516-532, 1976.
[7] J. G. Proakis and M. Salehi, Communication systems engineering. New Jersey: Prentice Hall, 2002.
[8] J. R. Barry, A. Kavcic, S. W. McLaughlin, A. Nayak, and W. Zeng, "Iterative timing recovery," IEEE Signal Processing Mag., vol. 2, pp. 89-102, 2004.
[9] P. Kovintavewat, J. R. Barry, M. F. Erden, and E. M. Kurtas, "Robustness of per-survivor iterative timing recovery in perpendicular recording channels," IEEE Trans. Magnetics, vol. 10, pp. 807-808, 2005.
[10] B. Mielczarek, Turbo codes and channel estimation in wireless systems, PhD Thesis, Signals and Systems, Chalmers University of Technology, Goteborg, 2002.
[11] J. M. Walsh, C. R. Johnson, and P. A. Regalia, "Joint synchronization and decoding exploiting the turbo principle," in Proc. Conf. Inform. Sciences and Systems, 2004
[12] D. Tabak and B. C. Kuo, Optimal control by mathematical programming. New Jersey: Prentice Hall, 1971.
[13] H. Meyr, M. Moeneclaey, and S. Fechtel, Digital communication receivers: Synchronization, channel estimation, and signal processing. New York: John Wiley and sons, 1998.
[14] A. Nayak, J. Barry and S. McLaughlin, "Joint Timing Recovery and Turbo Equalization for Coded Partial Response Channels," IEEE Trans. Magnetics, vol. 38, no.5, pp. 2295-2297, Sept 2002.
[15] F. J. Harris and M. Rice, "Multirate digital filters for symbol timing synchronization in software defined radios," IEEE journal on selected areas in commun., vol. 19, no. 12, pp. 2346-2357, 2001.
[16] F. J. Harris, Multirate signal processing for communication systems. New Jersey: Prentice Hall, 2004.
[17] N. Noels, C. Herzet, A. Dejonghe, et al., "Turbo synchronization: an EM interpretation," In Proc. IEEE international Conference on Communications (ICC ÔÇÿ03), Anchorage, Alaska, USA, May 2003.
[18] N. Noels, H. Wymeerisch, H. Steendam and M. Moeneclay, "The true Cramer-Rao bound for timing recovery from a bandlimited linearly modulated waveform with unknown carrier phase and frequency," IEEE Trans. Commun., vol. 52, no. 3, pp. 473-483, March 2004.
[19] R. Koetter, A.C. Singer and M. Tuchler, "Turbo equalization," IEEE Signal Processing Magazine, vol. 21, no. 1, pp. 67-80, January 2004.
[20] J. Hagenauer and P. Hoher, "A Viterbi algorithm with soft-decision outputs and its applications," IEEE Trans. Commun., vol. 47, pp. 1680- 1686, 1989.
[21] N. Metropolis and S. Ulam, "The Monte Carlo method," American Statistic Association Journal, vol. 44, pp. 335-341, 1949.
[22] T. O. Olwal, M. A. van Wyk, D. Chatelain, M. Odhiambo and B. J. van Wyk, "Low variance timing recovery in turbo receivers," In Proc. IEEE 13th International Conference on Telecommunication (ICT ÔÇÿ06), Funchal, Portugal, May 2006.
[23] T. O. Olwal, M. A. van Wyk, D. Chatelain, M. Odhiambo and B.J. van Wyk, "Cramer-Rao bound on timing recovery for GSM receivers," In Proc. IEEE ICTe Africa2006, Nairobi, Kenya, May 2006.
[24] T. O. Olwal, M. A. van Wyk, B. J. van Wyk, M. Odhiambo and D. Chatelain, "Improved timing recovery in wireless mobile receivers" African Journal of Science and Technology (AJST), vol. 8, no. 1, pp. 71- 86, 2007.
[25] A. Dejonghe, X. Jaspar, X. Wautelet and L. Vandendorpe, "Assessing the performance of turbo-equalised bit-interleaved turbo-coded modulation," In Proc. Symposium on Commun. Vehicular Tech., Ghent (Belgium), 2004.
[26] N. Noels, H. Steendam and M. Moeneclay, "On the Cramer-Rao lower Bound and the performance of synchronizers for (turbo) encoded systems," In Proc. 5th IEEE Workshop Sig. Proc. Advances in Wirel. Commun., Lisbon, Portugal, July 11-14, 2004.
[27] P. Robertson, P. Hoeher and E. Villebrun, "Optimal and Sub-optimal maximum a posterior algorithms suitable for turbo decoding," In European Trans. On Telecomm. vol. 8, no. March/ April, pp. 119-125, 1997.