Authors:
Roy Shevach
1
and
Monika Pinchas
2
Affiliations:
1
Ariel University of Samaria, Israel
;
2
Ariel University of Samaria, Israel
Keyword(s):
Blind Equalization, Residual ISI.
Related
Ontology
Subjects/Areas/Topics:
Adaptive Systems
;
Digital Signal Processing
;
Signal Processing in Communications
;
Telecommunications
Abstract:
Recently, closed-form approximated expressions were obtained for the residual Inter-Symbol Interference
(ISI) obtained by blind adaptive equalizers valid for the real or two independent quadrature carrier case such
as the 16 Quadrature Amplitude Modulation (QAM) input. In this paper we propose for the complex and
dependent quadrature carrier case (such as the 32QAM source), a closed-form approximated expression for
the achievable residual ISI which depends on the step-size parameter, equalizer’s tap length, input signal
statistics, channel power and SNR. This approximated expression is applicable for blind adaptive equalizers
where the error is fed into the adaptive mechanism, which updates the equalizer‘s taps and can be expressed
as a polynomial function up to order five of the equalized output. Godard’s algorithm for example, applies a
third order polynomial function to the adaptation mechanism of the equalizer thus belongs to the above-mentioned
type of equalizers. Since the chan
nel power is measurable, or can be calculated if the channel
coefficients are given, there is no need to perform any simulation with various step-size parameters and
different values of SNR to reach the required residual ISI for the dependent quadrature carrier input case.
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