WF on specification-based enhancements on CSI-RS and CSI feedback

Background Goal: description of specification-based enhancements on CSI-RS and CSI feedback Summarize the available schemes in the TR Proposal: Capture the following description in the TR

Definition Non-precoded CSI-RS based schemes include the following: a serving eNB configures CSI-RS ports that are one-to-one mapped to TXRUs, or a static and non-UE specific (1-D or 2-D) CSI-RS to TXRU virtualization is utilized to map one CSI-RS port onto multiple TXRUs. In this category of schemes all CSI-RS ports have cell-wide coverage. Beamformed CSI-RS based schemes include the following: a serving eNB applies CSI-RS port-to-TXRU virtualization

Schemes for non-precoded CSI-RS A scheme is associated with codebook(s) for CSI reporting and the associated CSI reporting modes Precoding matrix/vector for CSI reporting: 𝑾= 𝑾 1 𝑾 2 𝑾 is used for a downlink transmission hypothesis Potential specification enhancement on CSI reporting: PMI(s) corresponding to W1 and/or W2 If multiple PMIs are reported for W1 or W2, different feedback rate and/or granularity for the multiple PMIs may or may not be used RI: A single RI or multiple RIs CQI

Schemes for beamformed CSI-RS A beam corresponds to one resource which a UE measures Potential specification enhancement on CSI reporting: Cat 1: UE to select one or more beams from multiple beams Report an indication of selected beam(s) Codebook-based feedback across ports within each of the selected beam(s) Cat 2: eNB to transmit one beam Codebook-based feedback across ports