Applications of a variable step size algorithm to QCEE adaptive IIR filters

The quadratic constraint equation error (QCEE) method was proposed by Ho and Chan (see ibid., vol.43, no.1, p.51-62, 1995) to achieve bias removal for the equation error adaptive IIR filters. However, this approach is limited to slow convergence in estimation when a small step size is used; large step sizes lead to significant misadjustment. This article presents a variable step size (VSS) technique to greatly improve the QCEE under its quadratic constraint to achieve both fast convergence and reduced misadjustment for adaptive IIR filters.