A user equipment, UE, comprising: a transceiver; and a processor operably connected to the transceiver, the processor configured to: receive, from a base station via the transceiver, configuration information for a channel state information, CSI, reporting, wherein the configuration information includes a number of one or more antenna ports for a first dimension ( N 1) of a two-dimensional, 2D, dual-polarized antenna array, and a number of one or more antenna ports for a second dimension ( N 2) of the 2D dual-polarized antenna array, wherein a number of antenna ports for the 2D dual-polarized antenna array is 2 N 1 N 2; determine, according to the configuration information, a first precoding matrix indicator, PMI, of a dual-stage codebook, wherein the first PMI includes at least one of a first index ( i 1,1) for the first dimension or a second index ( i 1,2) for the second dimension; and transmit, to the base station via the transceiver, the first PMI on an uplink channel, wherein, if one of the number of one or more antenna ports for the first dimension ( N 1) and the number of one or more antenna ports for the second dimension ( N 2) equals one, the first PMI is determined to include one codebook index of the first PMI, and the first PMI corresponds to a bit sequence of the one codebook index, and wherein, if each of the number of one or more antenna ports for the first dimension ( N 1) and the number of one or more antenna ports for the second dimension ( N 2) is greater than one, the first PMI is determined to include the first index ( i 1,1) for the first dimension and the second index ( i 1,2) for the second dimension, and the first PMI corresponds to a concatenated bit sequence of the first index ( i 1,1) and the second index ( i 1,2). a transceiver; and a processor operably connected to the transceiver, the processor configured to: receive, from a base station via the transceiver, configuration information for a channel state information, CSI, reporting, wherein the configuration information includes a number of one or more antenna ports for a first dimension ( N 1) of a two-dimensional, 2D, dual-polarized antenna array, and a number of one or more antenna ports for a second dimension ( N 2) of the 2D dual-polarized antenna array, wherein a number of antenna ports for the 2D dual-polarized antenna array is 2 N 1 N 2; determine, according to the configuration information, a first precoding matrix indicator, PMI, of a dual-stage codebook, wherein the first PMI includes at least one of a first index ( i 1,1) for the first dimension or a second index ( i 1,2) for the second dimension; and transmit, to the base station via the transceiver, the first PMI on an uplink channel, wherein, if one of the number of one or more antenna ports for the first dimension ( N 1) and the number of one or more antenna ports for the second dimension ( N 2) equals one, the first PMI is determined to include one codebook index of the first PMI, and the first PMI corresponds to a bit sequence of the one codebook index, and wherein, if each of the number of one or more antenna ports for the first dimension ( N 1) and the number of one or more antenna ports for the second dimension ( N 2) is greater than one, the first PMI is determined to include the first index ( i 1,1) for the first dimension and the second index ( i 1,2) for the second dimension, and the first PMI corresponds to a concatenated bit sequence of the first index ( i 1,1) and the second index ( i 1,2). receive, from a base station via the transceiver, configuration information for a channel state information, CSI, reporting, wherein the configuration information includes a number of one or more antenna ports for a first dimension ( N 1) of a two-dimensional, 2D, dual-polarized antenna array, and a number of one or more antenna ports for a second dimension ( N 2) of the 2D dual-polarized antenna array, wherein a number of antenna ports for the 2D dual-polarized antenna array is 2 N 1 N 2; determine, according to the configuration information, a first precoding matrix indicator, PMI, of a dual-stage codebook, wherein the first PMI includes at least one of a first index ( i 1,1) for the first dimension or a second index ( i 1,2) for the second dimension; and transmit, to the base station via the transceiver, the first PMI on an uplink channel, wherein, if one of the number of one or more antenna ports for the first dimension ( N 1) and the number of one or more antenna ports for the second dimension ( N 2) equals one, the first PMI is determined to include one codebook index of the first PMI, and the first PMI corresponds to a bit sequence of the one codebook index, and wherein, if each of the number of one or more antenna ports for the first dimension ( N 1) and the number of one or more antenna ports for the second dimension ( N 2) is greater than one, the first PMI is determined to include the first index ( i 1,1) for the first dimension and the second index ( i 1,2) for the second dimension, and the first PMI corresponds to a concatenated bit sequence of the first index ( i 1,1) and the second index ( i 1,2).