5G • RAN
PMI
Precoding Matrix Indicator
Codebook index reported by UE indicating preferred antenna precoding weights for optimal beam alignment.
Technical Explanation
Based on CSI-RS channel estimation, the UE searches standardized 3GPP codebooks to find the precoding matrix that maximizes received SNR. The selected matrix index (PMI) is fed back to the gNodeB, allowing the base station to steer antenna array energy directly toward the UE.
Key Functions
- Identifies preferred beamforming weights from standardized codebook
- Consists of wideband and subband precoding recommendations
- Feeds back antenna array phase and amplitude recommendations
Specifications
3GPP TS 38.214
Interfaces
Uu
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