21. The wireless communication apparatus of claim 18 , wherein the circuitry is further configured to include one or more of the modeled impairment correlation terms in the subset regardless of whether their respective model fitting parameters satisfy the threshold.
18. The wireless communication apparatus of claim 17 , wherein the circuitry is configured to select a subset of the modeled impairment correlation terms by selecting the modeled impairment correlation terms having corresponding model fitting parameters that satisfy a threshold.