A user equipment comprising: at least one transceiver; and at least one processor operatively coupled to the at least one transceiver, configured to: receive, from a base station, a first set of channel state reference signals, CSI-RS, according to a first channel state information, CSI, process configuration; receive, from the base station, a second set of CSI-RS according to a second CSI process configuration; and transmit, to the base station, first information including a first rank indicator, RI, on physical uplink control channel, PUCCH, in a RI reporting subframe according to the first CSI process configuration; and transmit, to the base station, second information including a channel quality indicator, CQI, and a first precoding matrix indicator, PMI, on PUCCH in a CQI/PMI reporting subframe according to the first CSI process configuration, wherein the CQI corresponding to a rank-2 composite precoder is determined when a maximum of the first RI and a second RI indicates rank-2, wherein the rank-2 composite precoder comprises two columns including: a first column being a Kronecker product of a first precoding vector and a second precoding vector, and a second column being a Kronecker product of a third precoding vector and a fourth precoding vector, wherein, the first column and the second column are scaled with 2, so that a norm of each of the first column and the second column is 1 / 2 when the first RI indicates rank-2 and the second RI indicates rank-2, wherein the first precoding vector and the third precoding vector comprise two columns of a first rank-2 precoding matrix from a first set of rank-2 candidate precoding matrices and the second precoding vector and the fourth precoding vector comprise two columns of a second rank-2 precoding matrix from a second set of rank-2 candidate precoding matrices, wherein the first PMI corresponds to the first rank-2 precoding matrix; wherein the first RI is a RI reported most recently according to the first CSI process configuration prior to transmitting the second information, wherein the second RI is a RI reported most recently according to the second CSI process configuration prior to transmitting the second information, and wherein a composite rank is one when both of the first RI and the second RI indicate rank 1. at least one transceiver; and at least one processor operatively coupled to the at least one transceiver, configured to: receive, from a base station, a first set of channel state reference signals, CSI-RS, according to a first channel state information, CSI, process configuration; receive, from the base station, a second set of CSI-RS according to a second CSI process configuration; and transmit, to the base station, first information including a first rank indicator, RI, on physical uplink control channel, PUCCH, in a RI reporting subframe according to the first CSI process configuration; and transmit, to the base station, second information including a channel quality indicator, CQI, and a first precoding matrix indicator, PMI, on PUCCH in a CQI/PMI reporting subframe according to the first CSI process configuration, receive, from a base station, a first set of channel state reference signals, CSI-RS, according to a first channel state information, CSI, process configuration; receive, from the base station, a second set of CSI-RS according to a second CSI process configuration; and transmit, to the base station, first information including a first rank indicator, RI, on physical uplink control channel, PUCCH, in a RI reporting subframe according to the first CSI process configuration; and transmit, to the base station, second information including a channel quality indicator, CQI, and a first precoding matrix indicator, PMI, on PUCCH in a CQI/PMI reporting subframe according to the first CSI process configuration, wherein the CQI corresponding to a rank-2 composite precoder is determined when a maximum of the first RI and a second RI indicates rank-2, wherein the rank-2 composite precoder comprises two columns including: a first column being a Kronecker product of a first precoding vector and a second precoding vector, and a second column being a Kronecker product of a third precoding vector and a fourth precoding vector, a first column being a Kronecker product of a first precoding vector and a second precoding vector, and a second column being a Kronecker product of a third precoding vector and a fourth precoding vector, wherein, the first column and the second column are scaled with 2, so that a norm of each of the first column and the second column is 1 / 2 when the first RI indicates rank-2 and the second RI indicates rank-2, wherein the first precoding vector and the third precoding vector comprise two columns of a first rank-2 precoding matrix from a first set of rank-2 candidate precoding matrices and the second precoding vector and the fourth precoding vector comprise two columns of a second rank-2 precoding matrix from a second set of rank-2 candidate precoding matrices, wherein the first PMI corresponds to the first rank-2 precoding matrix; wherein the first RI is a RI reported most recently according to the first CSI process configuration prior to transmitting the second information, wherein the second RI is a RI reported most recently according to the second CSI process configuration prior to transmitting the second information, and wherein a composite rank is one when both of the first RI and the second RI indicate rank 1.