Patent ID: 9548803
Date: 2017-01-17
CPC Classifications: H04B,H04L

Claim:
1. A method for operating a base station, the method comprising: receiving a precoding matrix indicator (PMI) from a first user equipment (UE) device in a first sector of the base station, wherein the PMI identifies a particular row from within a designated subset of a codebook, wherein the codebook includes constant modulus codewords and at least a first codeword that is of non-constant modulus, wherein the designated subset of the codebook includes only the constant modulus codewords, wherein the constant modulus codewords include at least single-layer codewords; selecting a precoding matrix for downlink transmission to the first user equipment device using a first subset of two or more of a plurality of base station antennas, wherein the precoding matrix is selected from the designated subset of the codebook, wherein said selecting includes consideration of the received PMI; generating a plurality of transmit signals by precoding one or more layer signals using complex weights associated with the selected precoding matrix; and transmitting the transmit signals respectively through the first subset of two or more base station antennas; wherein, for the first sector, said receiving and said selecting are constrained to be from within said designated subset of the codebook for all closed-loop 2TX-enabled UE devices in the first sector; wherein the method further comprises, for a second UE device in a second sector of the base station: