Observed misconvergence in the constant modulus adaptive algorithm

Practical application of the constant modulus algorithm (CMA) has demonstrated a number of circumstances in which CMA fails to converge, or, equally bad from a practical standpoint, converges to a solution which fails to equalize the input signal. The authors describe several situations in which misconvergence occurs, suggesting that a firmer analytical understanding is needed of the behavior of blind algorithms in the presence of cyclostationary and/or quasi-periodic, nonwhite inputs. While this analytical understanding is not yet established, the practical experience reported should be directly useful to those designing new digital communications systems. An example presented, is the use of CMA to equalize quadrature amplitude modulation (QAM) signals used to broadcast high-definition television signals.<<ETX>>

[1]  D. Godard,et al.  Self-Recovering Equalization and Carrier Tracking in Two-Dimensional Data Communication Systems , 1980, IEEE Trans. Commun..

[2]  J. Treichler,et al.  A new approach to multipath correction of constant modulus signals , 1983 .

[3]  A. Benveniste,et al.  Blind Equalizers , 1984, IEEE Trans. Commun..

[4]  Michael G. Larimore,et al.  The tone capture properties of CMA-based interference suppressors , 1985, IEEE Trans. Acoust. Speech Signal Process..

[5]  G. J. Foschini,et al.  Equalizing without altering or detecting data , 1985, AT&T Technical Journal.

[6]  R. Gooch,et al.  Specification and development of an equalizer-demodulator for wideband digital microwave radio signals , 1988, MILCOM 88, 21st Century Military Communications - What's Possible?'. Conference record. Military Communications Conference.