. "The apparatus according to claim 1, wherein said feedforward matrix-vector product unit generates said feedforward vector to be substantially equal to ??k=W??k, where ??k is said modulo-reduced vector, W=(I+QHG???1H1Q)???1 is said feedforward matrix, Q is an inverse transformation matrix, G is circulant, and H1 is triangular Toeplitz." . . .