1. A memory device tangibly embodying a data structure, the data structure comprising: a first codeword P l ; and a plurality of codewords P l , l=2. .. 2 L , where 2 L comprises a number of said plurality of codewords wherein P l =VQ l V H P l where V comprises a unitary matrix comprising eigen vectors, Q comprises a diagonal matrix, and V H comprises a hermitian eigen matrix, wherein said data structure is further configured to be accessed by processing apparatus of an electronic device operative in a wireless communications network so that the codewords can be used by the electronic device to perform communication operations.