Operation for 3d beam forming in a wireless communication system

A method for a user equipment (UE) to report channel status information to a network in a wireless communication system, the method comprising:

• receiving reference signals from the network;
• and
• reporting the channel status information comprising precoding matrix information to the network, wherein the precoding matrix information corresponds to multiple codebook indices including a first codebook index and a second codebook index, wherein the first codebook index corresponds to a first type precoding matrix selected from a first type codebook for a first dimension, wherein the second codebook index corresponds to a second type precoding matrix selected from a second type codebook for a second dimension,
• wherein the first type codebook has a format of a first matrix including one or more elements expressed as a first exponential function dividing 2π by K and multiplying k, wherein the K and the k are non-negative integers,
• wherein the second type codebook has a format of a second matrix including one or more elements expressed as a second exponential function dividing 2π by N and multiplying n, wherein the N and the n are non-negative integers,
• wherein the first codebook index indicates the k within a range between 0 to K/2−1, and
• wherein the second codebook index indicates the n within a range between 0 to N−1.

A user equipment (UE) reporting channel status information to a network in a wireless communication system, the UE comprising:

• a transceiver configured to receive reference signals from the network and to report the channel status information to the network;
• and
• a processor connected to the transceiver and to configure the channel status information to include precoding matrix information, wherein the precoding matrix information corresponding to multiple codebook indices including a first codebook index and a second codebook index, wherein the first codebook index corresponds to a first type precoding matrix selected from a first type codebook for a first dimension, wherein the second codebook index corresponds to a second type precoding matrix selected from a second type codebook for a second dimension,
• wherein the first type codebook has a format of a first matrix including one or more elements expressed as a first exponential function dividing 2π by K and multiplying k, wherein the K and the k are non-negative integers,
• wherein the second type codebook has a format of a second matrix including one or more elements expressed as a second exponential function dividing 2π by N and multiplying n, wherein the N and the n are non-negative integers,
• wherein the processor sets the first codebook index to indicate the k within a range between 0 to K/2−1, and
• wherein the processor sets the second codebook index to indicate the n within a range between 0 to N−1.