Patent ID: 8693421

Claim:
A method of channel state information (CSI) feedback for communication between a base station (eNB) and a plurality of user equipment (UE), comprising the steps of: each user equipment transmitting via Physical Uplink Control CHannel (PUCCH) a CSI feedback signal having: a first mode with a first report jointly coding Rank Indicator (RI) and a first precoding matrix (W 1 ), and with a second report coding Channel Quality Indicator (CQI) and a second precoding matrix (W 2 ), and a second mode with a first report coding Rank Indicator (RI), and with a second report coding Channel Quality Indicator (CQI) and jointly coding the first precoding matrix (W 1 ) and the second precoding matrix (W 2 ); wherein said step of jointly coding Rank Indicator (RI) and the first precoding matrix (W 1 ) employs codebook sub-sampling; wherein said step of jointly coding the first precoding matrix (W 1 ) and the second precoding matrix (W 2 ) employs codebook sub-sampling; and wherein said step of jointly coding Rank Indicator (RI) and the first precoding matrix (W 1 ) employs codebook sub-sampling into a maximum of 5 bits as follows: RI Chosen W1 index for sub-sampling (i 1 ) 1 0, 2, 4, 6, 8, 10, 12, 14 (no overlap) 2 0, 2, 4, 6, 8, 10, 12, 14 (no overlap) 3 0, 2 (no overlap) 4 0, 2 (no overlap).