Codebook for full-dimension multiple input multiple output communications
Various embodiments include an apparatus to be employed by an enhanced Node B (eNB), the apparatus comprising communication circuitry to receive, from a user equipment (UE), feedback information and control circuitry, coupled with the communication circuitry, to identify a codeword from a three-dimensional codebook based on the feedback information received from the UE, wherein the communication circuitry is further to precode data to be transmitted to the UE based on the codeword. An apparatus to be employed by a UE and additional methods are described.
1. One or more non-transitory, computer-readable media having instructions stored thereon, wherein the instructions, in response to execution by a user equipment (UE), cause the UE to:
determine channel state information (CSI) based on a channel state information reference signal (CSI-RS) received by the UE;
select a first index, a second index, and a third index based on the CSI, wherein the first index, the second index, and the third index comprise a precoding matrix indicator for a three-dimensional codebook; and
generate feedback for a base station, wherein the feedback includes an indication of the first index, the second index, and the third index,
wherein:
the three-dimensional codebook includes a plurality of codewords, wherein each of the plurality of codewords is constructed as a product of a first matrix, a second matrix, and a third matrix, and wherein the first index corresponds to the first matrix, the second index corresponds to the second matrix, and the third index corresponds to the third matrix; and
the first matrix is constructed via combination of a portion of the plurality of codewords using discrete Fourier transform (DFT) vectors and the portion of the plurality of codewords using non-DFT vectors.
2. The one or more non-transitory, computer-readable media of claim 1 , wherein the base station has more than eight antenna ports.
3. The one or more non-transitory, computer-readable media of claim 1 , wherein the first matrix comprises a block diagonal matrix.
4. The one or more non-transitory, computer-readable media of claim 1 , wherein dimensions of the three-dimensional codebook are of 2N*M rows and 1 to 2N columns, where M is a number of rows of an antenna array associated with the base station and N is a number of columns of the antenna array.
5. The one or more non-transitory, computer-readable media of claim 1 , wherein the feedback further includes a rank indicator.
6. The one or more non-transitory, computer-readable media of claim 1 , wherein the first index, the second index, and the third index are selected based on the three-dimensional codebook stored on the UE.
7. A user equipment (UE), comprising:
memory to store a three-dimensional codebook; and
circuitry to:
determine channel state information (CSI) based on a channel state information reference signal (CSI-RS) received by the UE;
select a precoding matrix indicator for a codeword from the three-dimensional codebook, wherein the precoding matrix indicator includes a first index, a second index, and a third index; and
generate feedback for a base station, wherein the feedback includes an indication of the first index, the second index, and the third index,
wherein:
the three-dimensional codebook includes a plurality of codewords, wherein each of the plurality of codewords is constructed as a product of a first matrix, a second matrix, and a third matrix, and wherein the first index corresponds to the first matrix, the second index corresponds to the second matrix, and the third index corresponds to the third matrix; and
the first matrix is constructed via combination of a portion of the plurality of codewords using discrete Fourier transform (DFT) vectors and the portion of the plurality of codewords using non-DFT vectors.
8. The UE of claim 7 , wherein the base station has more than eight antenna ports.
9. The UE of claim 7 , wherein dimensions of the three-dimensional codebook are of 2N*M rows and 1 to 2N columns, where M is a number of rows of an antenna array associated with the base station and N is a number of columns of the antenna array.
10. The UE of claim 7 , wherein the report further includes a rank indicator.
11. The UE of claim 7 , wherein a size of the three-dimensional codebook is defined by radio resource control (RRC) signaling.