Method and apparatus for reduced feedback FD-MIMO
A method for operating a base station includes receiving an uplink signal from a user equipment (UE), wherein the uplink signal includes a precoding matrix indicator (PMI) associated with a first precoder index of a codebook determined by a first and a second precoder indices, and a channel quality indicator (CQI). The method includes applying an open-loop diversity operation to at least one data stream including quadrature amplitude modulation (QAM) symbols to generate N_B signal streams and applying a precoding matrix to the N_B signal streams to generate a larger number of N_TX data streams to be transmitted via a plurality of antennas.
1. A method for operating a user equipment (UE), the method comprising:
determining a precoding matrix indicator (PMI) associated with a first precoder index of a codebook determined by a first and a second precoder indices;
calculating a channel quality indicator (CQI) in accordance with an open-loop operation and a precoding matrix associated with the PMI; and
transmitting an uplink signal to a base station, wherein the uplink signal includes the PMI and the CQI, wherein the open-loop operation and the precoding matrix are associated with at least one of two dimensions of a two dimensional precoder.
2. The method of claim 1 , wherein the CQI and the PMI are transmitted on two separate uplink subframes.
3. The method of claim 1 , wherein an open-loop diversity operation maps one or a group of consecutive QAM symbols onto at least one of a plurality of columns of the precoding matrix including Discrete Fourier Transform (DFT) vectors for each of two polarization groups.
4. The method of claim 1 , further comprising:
determining a value of a reporting parameter associated with a value of N_B signal streams; and
transmitting the value of the reporting parameter to the base station.
5. A user equipment (UE) comprising:
a transceiver configured to receive at least one data stream including quadrature amplitude modulation (QAM) symbols; and
at least one processor configured to:
determine a precoding matrix indicator (PMI) associated with a first precoder index of a codebook determined by a first and a second precoder indices;
calculate a channel quality indicator (CQI) in accordance with an open-loop operation and a precoding matrix associated with the PMI; and
transmit an uplink signal to a base station, wherein the uplink signal includes the PMI and the CQI, wherein the open-loop operation and the precoding matrix are associated with at least one of two dimensions of a two dimensional precoder.
6. The UE of claim 5 , wherein the CQI and the PMI are transmitted on two separate uplink subframes.
7. The UE of claim 5 , wherein an open-loop diversity operation maps one or a group of consecutive QAM symbols onto a plurality of columns of the precoding matrix including Discrete Fourier Transform (DFT) vectors for each of two polarization groups.
8. The UE of claim 5 , wherein the at least one processor is configured to determine a value of a reporting parameter associated with a number of N_B signal streams and transmit the value to the base station.