US Patent 7804825 Matrix expansion lattice

A cross-connect switching system includes a plurality of three stage switching arrays and an expansion switching array, wherein a second stage of each of the three stage switching arrays includes an expansion section comprising switches which facilitate interconnection of each three stage array to the expansion switching array. In one embodiment, the expansion switching array includes a plurality of square arrays, each having Q inputs and Q outputs and wherein the second stages of the three stage arrays each include 1 . . . M+1 . . . M+p vertical stages which connect to the square “D” arrays of the central expansion switching array.