PUCCH Feedback Mode for Beamformed CSI-RS Reporting
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Solution Overview
Problem
The existing PUCCH feedback mode in LTE Rel-13 does not consider reporting a beamforming indication (BI) for the beamformed CSI-RS mechanism, and the existing feedback mode cannot be applied to the new 2D codebook used in Rel-13, necessitating a new PUCCH feedback mode for both beamformed and non-precoded CSI-RS mechanisms to effectively adapt and reduce design complexity.
Innovation Solution
A method is introduced where user equipment (UE) receives CSI-RS resources and determines a rank indication (RI) and/or a beamforming indication (BI) on subbands, calculating a channel quality indicator (CQI) and reporting these on a physical uplink control channel (PUCCH) using redesigned PUCCH feedback modes, which include various reporting formats and submodes to adapt to both beamformed and non-precoded CSI-RS mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the existing PUCCH feedback mode is used for beamformed CSI-RS mechanism in Rel-13, then the feedback structure remains simple and compatible with previous versions, but the beamforming indication (BI) cannot be reported and the mode cannot adapt to the new 2D codebook
Solution Approach 1:
The feedback report is segmented into multiple formats (Format 1, Format 2, Format 3) with different structures for reporting BI, RI, PMI, and CQI. Each format is optimized for specific scenarios, allowing the system to adapt to beamformed CSI-RS while managing complexity through structured segmentation of feedback elements
Solution Approach 2:
The patent extends the traditional feedback mode by adding a new dimension - the beamforming indication (BI) that indicates selected CSI-RS resources. This additional dimension enables adaptation to 3D beamforming and 2D codebooks while maintaining compatibility with existing feedback structures through the introduction of new report formats
2Adaptability or versatility
If a new PUCCH feedback mode is designed to support BI reporting and 2D codebook, then adaptability to Rel-13 mechanisms is improved, but the design complexity of feedback types and modes increases
Solution Approach 1:
The new feedback formats are designed to be universal, supporting both beamformed and non-precoded CSI-RS mechanisms through the same PUCCH structure. The formats can report BI, RI, PMI, and CQI in various combinations, making them adaptable to different Rel-13 mechanisms without requiring separate feedback designs for each case
Solution Approach 2:
The feedback mode introduces dynamic selection of reporting formats based on configuration parameters and channel conditions. The UE can dynamically choose among Format 1, Format 2, and Format 3 depending on whether BI reporting is needed, whether subband or wideband CQI is required, and the specific Rel-13 mechanism being used, thereby managing complexity through dynamic adaptation
3Adaptability or versatility
If multiple reporting formats are introduced for different feedback scenarios, then the system can adapt to various CSI-RS mechanisms, but the complexity of selecting and managing feedback formats increases
Solution Approach 1:
The network configures the appropriate feedback format and parameters in advance through RRC signaling before actual feedback transmission. This preliminary configuration specifies which format (1, 2, or 3) should be used, eliminating the need for complex real-time format selection by the UE and simplifying the operation while maintaining flexibility through pre-planned format assignment
Data Source
AI summary
The present disclosure relates to a method for measuring and feeding back channel state information. In one example method, a user equipment (UE) receives a first channel state information report type configured by a base station and K channel state information-reference signal (CSI-RS) resources transmitted by the base station. The UE determines, according to the first channel state information report type, at least one of a rank indication (RI) and a beamforming indication (BI) on S subbands of a wideband on which the K CSI-RS resources are transmitted. The UE calculates a channel quality indicator (CQI) on the S subbands The UE reports the determined at least one of the RI and the BI, and the calculated CQI on a physical uplink control channel (PUCCH) by using a report.