1. A method of predistorting signals using an augmented reverse twin nonlinear two-box model to compensate for a nonlinear power amplifier, comprising the steps of: accepting an input signal, x in _ Poly _ R , the input signal being a digitized signal; predistorting the input signal, x in _ Poly _ R , in accordance with a memory polynomial function including cross terms to produce a first predistorted input signal, x out _ Poly _ R , the memory polynomial function being characterized by the relation: x out ⁢ ⁢ _ ⁢ ⁢ Poly_R ⁡ ( n ) = ∑ j = 0 M 1 ⁢ ∑ i = 1 N 1 ⁢ a ij · x in_Poly ⁢ _R ⁡ ( n - j ) ·  x in_Poly ⁢ _R ⁡ ( n - j )  i - 1 + ∑ j = 0 M 2 ⁢ ∑ i = 2 N 2 ⁢ ∑ i = 1 L 2 ⁢ b ijl · x in_Poly ⁢ _R ⁡ ( n - j ) ·  x in_Poly ⁢ _R ⁡ ( n - j - l )  i - 1 + ∑ j = 0 M 3 ⁢ ∑ i = 2 N 3 ⁢ ∑ i = 1 L 3 ⁢ c ijl · x in_Poly ⁢ _R ⁡ ( n - j ) ·  x in_Poly ⁢ _R ⁡ ( n - j + l )  i - 1 ; wherein x in _ Poly _ R and x out _ Poly _ R are input and output waveforms of the output polynomial, respectively, N 1 , N 2 , and N 3 are the nonlinearity orders of aligned, lagging and leading polynomial function terms, respectively, M 1 , M 2 , and M 3 represent memory depths of the aligned, lagging and leading polynomial functions, respectively, L 2 , and L 3 represent lagging and leading cross-terms orders, respectively, a ij , b ijl , and c ijl are the coefficients of the aligned, lagging and leading polynomial functions, respectively; and subsequently predistorting the first predistorted input signal, x out _ Poly _ R , using values in a look-up table of values computed from a memoryless polynomial to produce a second predistorted input signal, x out _ LUT _ R , for input to the nonlinear power amplifier.