Multi-TRP CSI Codebook Structure for Low-Overhead Precoder Feedback
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Solution Overview
Problem
Current wireless communication systems lack an efficient method for multi-TRP coherent joint transmission (CJT) CSI feedback, particularly in non-coherent joint transmission scenarios where multiple transmission and reception points (TRPs) operate independently without synchronization, leading to increased signaling overhead and suboptimal precoder selection for antenna panels.
Innovation Solution
A codebook structure is designed for multi-TRP CJT CSI feedback, allowing UEs to report preferred precoders efficiently by combining spatial and frequency basis selection matrices with reduced overhead, including mechanisms for reporting linear combination coefficients and phase/amplitude information across TRPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple TRPs operate independently without synchronization for non-coherent joint transmission, then system flexibility and deployment ease are improved, but signaling overhead increases and precoder selection becomes suboptimal
Solution Approach 1:
The codebook is segmented into multiple codebook groups, each associated with a specific TRP. This segmentation allows the UE to report CSI feedback for multiple TRPs independently, reducing the overall signaling overhead while maintaining the ability to support flexible multi-TRP deployments. Each codebook group contains precoders tailored to the specific channel characteristics of its associated TRP.
Solution Approach 2:
The patent introduces a new dimension to CSI feedback by incorporating TRP-specific codebook group indices in addition to traditional PMI reporting. This dimensional expansion allows the system to efficiently represent multi-TRP channel states without proportionally increasing signaling overhead, as the codebook structure itself encodes TRP identification information.
2Adaptability or versatility
If multiple TRPs operate independently without synchronization, then system flexibility is improved, but precoder selection accuracy deteriorates
Solution Approach 1:
Each codebook group is designed with local quality optimized for its specific TRP's channel characteristics. The precoders within each codebook group are tailored to the spatial and frequency properties of the corresponding TRP, ensuring accurate precoder selection for each individual TRP while maintaining overall system flexibility through the multi-codebook structure.
Solution Approach 2:
By segmenting the codebook into TRP-specific groups, the system can provide precise, localized precoder recommendations for each TRP independently. This segmentation enables the UE to select the most appropriate precoder for each TRP based on its specific channel conditions, improving precoder selection accuracy without requiring TRP synchronization.
3Device complexity
If traditional codebook structures are used for multi-TRP feedback, then implementation simplicity is maintained, but feedback efficiency and throughput are reduced
Solution Approach 1:
The enhanced codebook structure serves multiple functions simultaneously: it provides TRP identification, spatial precoding, and frequency precoding all within a unified framework. This multi-functionality allows the system to support multi-TRP operations with improved throughput while avoiding the need for completely separate feedback mechanisms, thus limiting the increase in implementation complexity.
Solution Approach 2:
The patent enhances the traditional codebook structure by adding TRP-specific dimensions while preserving the core PMI reporting mechanism. This dimensional enhancement enables efficient multi-TRP feedback by encoding additional information (TRP identity and specific precoding preferences) within the extended codebook framework, improving throughput without proportionally increasing feedback overhead or processing complexity.
Data Source
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AI summary
Apparatus and methods are provided for port selection codebook configuration when a user equipment (UE) receives communicates with a plurality of transmission and reception points (TRPs). For multiple TRP (multi-TRP) coherent joint transmission (CJT) channel state information (CSI) reporting, a codebook is provided with a codebook structure by (I) or (II) in which t is a TRP index corresponding to a particular TRP, T is a total number of TRPs, (III) are Type II CSI codebooks reported for TRPs corresponding to index t, and (IV) are linear combination coefficients applied to each codebook for different TRPs. (V) for a spatial basis selection matrix (VI) a combination coefficient matrix (VII) and a frequency basis selection matrix (VIII).