Codebook sub-sampling for CSI feedback on PUCCH for 4Tx MIMO

摘要

Channel state information (CSI) feedback in a wireless communication system is disclosed. User equipment transmits a CSI feedback signal via a Physical Uplink Control CHannel (PUCCH). If the UE is configured in a first feedback mode, the CSI comprises a first report jointly coding a Rank Indicator (RI) and a first precoding matrix indicator (PMI1), and a second report coding Channel Quality Indicator (CQI) and a second precoding matrix indicator (PMI2). If the UE is configured in a second feedback mode, the CSI comprises a first report coding RI, and a second report coding CQI, PMI1 and PMI2. The jointly coded RI and PMI1 employs codebook sub-sampling, and the jointly coding PMI1, PMI2 and CQI employs codebook sub-sampling.

主权项

1. A method of channel state information (CSI) feedback between a base station and at least a user equipment, comprising:
transmitting, by the user equipment, a CSI feedback signal having: a first report coding a Rank Indicator (RI), and a second report coding a first precoding matrix indicator (PMI1) associated with the index of a first precoding matrix (W1), a second precoding matrix indicator (PMI2) associated with the index of a second precoding matrix (W2), and a Channel Quality Indicator (CQI), and wherein coding the PMI2 employs codebook sub-sampling as follows, for RI=3 and 4:Relationship between the secondPMI value and W2 index (i2)Value of theChosen W2 indexsecond PMIfor sub-samplingRI(IPMI2)(i2)30-15IPMI240-15 IPMI2.