Efficient Variants of Square Contour Algorithm for Blind Equalization of QAM Signals
A new distance-adjusted approach is proposed in
which static square contours are defined around an estimated
symbol in a QAM constellation, which create regions that
correspond to fixed step sizes and weighting factors. As a
result, the equalizer tap adjustment consists of a linearly
weighted sum of adaptation criteria that is scaled by a variable
step size. This approach is the basis of two new algorithms: the
Variable step size Square Contour Algorithm (VSCA) and the
Variable step size Square Contour Decision-Directed
Algorithm (VSDA). The proposed schemes are compared with
existing blind equalization algorithms in the SCA family in
terms of convergence speed, constellation eye opening and
residual ISI suppression. Simulation results for 64-QAM
signaling over empirically derived microwave radio channels
confirm the efficacy of the proposed algorithms. An RTL
implementation of the blind adaptive equalizer based on the
proposed schemes is presented and the system is configured to
operate in VSCA error signal mode, for square QAM signals
up to 64-QAM.
[1] D. Godard, Self recovering equalization and carrier tracking in twodimensional
data communication systems, IEEE Trans. Commun.
COM-28(1980) 1867-1875.
[2] J. R. Treichler, B. G. Agee, A new approach to multipath correction of
constant modulus signals, IEEE Trans. on Acoust., Speech, Signal
Processing ASSP-31 (2) (1983) 459-472
[3] S. U. H. Qureshi, Adaptive equalization, Proceedings of the IEEE 73 (9)
(1985)1349-1387.
[4] J. Liu, X. Lin, Equalization in high-speed communication systems,
IEEE Circuits and Systems Magazine (2004) 4-17.
[5] J. J. Shynk, R. P. Gooch, G. Krishnamurthy, C. K. Chan, A comparative
performance study of several blind equalization algorithms, SPIE 1565
(1991)102-117.
[6] J.-J. Werner, J. Yang, D. Harman, G. A. Dumont, Blind equalization for
broadband access, IEEE Communications Magazine (1999) 87-93.
[7] J. Yang, J.-J. Werner, G. A. Dumont, The multimodulus blind
equalization and its generalized algorithms, IEEE Journal on selected
areas in communication 20 (5) (2002) 997-1015.
[8] J. Yang, J.-J. Werner, G. A. Dumont, The multimodulus blind
equalization algorithm, in: Proc. Int. Conf. on Digital Signal Processing,
1997, pp. 127-130.
[9] Y. Sato, A method of self-recovering equalization for multilevel
amplitude-modulation systems, IEEE Trans. Commun. COM-23
(1975)679-682.
[10] T. Thaiupatump, S.A. Kassam, Square contour algorithm: A new
algorithm for blind equalization and carrier phase recovery, in: Proc.
37th Asilomar Conference on Signals, Systems and Computers, 2003,
pp. 647-651.
[11] T. Thaiupatump, L. He, S.A. Kassam, Square contour algorithm for
blind equalization of QAM signals, Signal Process. 86 (11) (2006)
3357-3370.
[12] K. Banovic, E. Abdel-Raheem, M. A. S. Khalid, A novel radiusadjusted
approach for blind adaptive equalization, IEEE Signal
Processing Letters 13 (1) (2006) 37-40.
[13] F. C. C. De Castro, M. C. F. De Castro, and D. S. Arantes, "Concurrent
blind deconvolution for channel equalization," in Proc. ICC, Helsinki,
Finland, Jun. 2001, pp. 366-371.
[14] A configurable fractionally-spaced blind adaptive equalizer for QAM
demodulators Digital Signal Processing, Volume 17, Issue 6, November
2007, Pages 1071-1088. Kevin Banović, Mohammed A.S. Khalid, Esam
Abdel-Raheem.
[1] D. Godard, Self recovering equalization and carrier tracking in twodimensional
data communication systems, IEEE Trans. Commun.
COM-28(1980) 1867-1875.
[2] J. R. Treichler, B. G. Agee, A new approach to multipath correction of
constant modulus signals, IEEE Trans. on Acoust., Speech, Signal
Processing ASSP-31 (2) (1983) 459-472
[3] S. U. H. Qureshi, Adaptive equalization, Proceedings of the IEEE 73 (9)
(1985)1349-1387.
[4] J. Liu, X. Lin, Equalization in high-speed communication systems,
IEEE Circuits and Systems Magazine (2004) 4-17.
[5] J. J. Shynk, R. P. Gooch, G. Krishnamurthy, C. K. Chan, A comparative
performance study of several blind equalization algorithms, SPIE 1565
(1991)102-117.
[6] J.-J. Werner, J. Yang, D. Harman, G. A. Dumont, Blind equalization for
broadband access, IEEE Communications Magazine (1999) 87-93.
[7] J. Yang, J.-J. Werner, G. A. Dumont, The multimodulus blind
equalization and its generalized algorithms, IEEE Journal on selected
areas in communication 20 (5) (2002) 997-1015.
[8] J. Yang, J.-J. Werner, G. A. Dumont, The multimodulus blind
equalization algorithm, in: Proc. Int. Conf. on Digital Signal Processing,
1997, pp. 127-130.
[9] Y. Sato, A method of self-recovering equalization for multilevel
amplitude-modulation systems, IEEE Trans. Commun. COM-23
(1975)679-682.
[10] T. Thaiupatump, S.A. Kassam, Square contour algorithm: A new
algorithm for blind equalization and carrier phase recovery, in: Proc.
37th Asilomar Conference on Signals, Systems and Computers, 2003,
pp. 647-651.
[11] T. Thaiupatump, L. He, S.A. Kassam, Square contour algorithm for
blind equalization of QAM signals, Signal Process. 86 (11) (2006)
3357-3370.
[12] K. Banovic, E. Abdel-Raheem, M. A. S. Khalid, A novel radiusadjusted
approach for blind adaptive equalization, IEEE Signal
Processing Letters 13 (1) (2006) 37-40.
[13] F. C. C. De Castro, M. C. F. De Castro, and D. S. Arantes, "Concurrent
blind deconvolution for channel equalization," in Proc. ICC, Helsinki,
Finland, Jun. 2001, pp. 366-371.
[14] A configurable fractionally-spaced blind adaptive equalizer for QAM
demodulators Digital Signal Processing, Volume 17, Issue 6, November
2007, Pages 1071-1088. Kevin Banović, Mohammed A.S. Khalid, Esam
Abdel-Raheem.
@article{"International Journal of Electrical, Electronic and Communication Sciences:54363", author = "Ahmad Tariq Sheikh and Shahzad Amin Sheikh", title = "Efficient Variants of Square Contour Algorithm for Blind Equalization of QAM Signals", abstract = "A new distance-adjusted approach is proposed in
which static square contours are defined around an estimated
symbol in a QAM constellation, which create regions that
correspond to fixed step sizes and weighting factors. As a
result, the equalizer tap adjustment consists of a linearly
weighted sum of adaptation criteria that is scaled by a variable
step size. This approach is the basis of two new algorithms: the
Variable step size Square Contour Algorithm (VSCA) and the
Variable step size Square Contour Decision-Directed
Algorithm (VSDA). The proposed schemes are compared with
existing blind equalization algorithms in the SCA family in
terms of convergence speed, constellation eye opening and
residual ISI suppression. Simulation results for 64-QAM
signaling over empirically derived microwave radio channels
confirm the efficacy of the proposed algorithms. An RTL
implementation of the blind adaptive equalizer based on the
proposed schemes is presented and the system is configured to
operate in VSCA error signal mode, for square QAM signals
up to 64-QAM.", keywords = "Adaptive filtering, Blind Equalization, Square
Contour Algorithm.", volume = "3", number = "3", pages = "457-9", }