Robust and Efficient Parametric Linear Equalization

As 3G DS-CDMA cellular systems evolve to higher data rates, linear equalization is being used to address inter-symbol interference introduced by dispersive channels. When parametric designs are employed, elements of an impairment or data covariance matrix must be computed as part of equalizer weight calculation. The conventional approach is to express these elements in terms of path delays and path coefficients. This approach requires a significant amount of computation, and performance is sensitive to errors in the path delay estimates. In this paper, an alternative approach is developed, based on directly estimating net channel coefficients corresponding to an extended set of delays that includes the tap or finger delays of the equalizer. This avoids the need for path delay estimates, improving robustness. Also, the elements of the impairment or data covariance can be expressed in terms of efficiently computed convolutions of these net channel coefficients, even though these elements correspond to correlations of cyclostationary interference. Complexity estimates are used to show computational savings, and performance simulations are used to show gains in robustness.