Patent ID: 8467470
Filing Date: 2013-06-18
Classification: H04L

Abstract:
1. A method implemented in a multi-rank beamforming wireless communications system, comprising: precoding a signal in accordance with a codebook comprising a plurality of codebook entries per rank; and transmitting the precoded signal, wherein the codebook restricts elements of codebook entries to be within a predetermined finite set of complex numbers, and each entry in the codebook has both equal column norm and equal row norm, wherein the wireless communications system has at least 4 transmission antennas, and wherein the codebook entries are matrices A that satisfy the following expression: where M is the number of transmit antennas, e 1 N =[1,0 , . . . , 0] T εC N , C N is an N-dimensional complex space, denotes a column vector, and i l denotes an index of the column vector.