LTE-A PUCCH Codebook Subset Design for PMI Feedback
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Solution Overview
Problem
The existing channel status information feedback methods in LTE-A systems face challenges in maintaining accurate PMI feedback precision within limited overhead, leading to decreased transmission performance on the PUCCH and potential bit error rate issues, especially when combined with RI or CQI feedback.
Innovation Solution
The method involves using a codebook structure where the C PUCCH is a subset of the C PUSCH, with specific code word selection criteria to ensure non-repetitive code words and optimal overhead management, allowing for precise PMI feedback without exceeding the 11-bit limit, thus supporting pre-coding technology effectively and maintaining compatibility with PUSCH feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If enhanced codebook feedback methods are used to improve PMI feedback precision, then transmission performance improves, but feedback overhead increases beyond the 11-bit limit on PUCCH
Solution Approach 1:
The codebook is segmented into two independent sub-codebooks (first sub-codebook and second sub-codebook) that can be separately selected and fed back. This segmentation allows the feedback information to be divided into multiple parts, enabling more precise channel state information feedback while managing the total feedback overhead by selecting only necessary sub-codebooks for different transmission scenarios.
2Reliability
If more code words are included in the codebook to improve channel information accuracy, then transmission performance improves, but the complexity of codebook management and selection increases
Solution Approach 1:
The codebook is divided into multiple sub-codebooks with different properties (e.g., different ranks, different beam directions). This segmentation reduces the complexity of codebook management by allowing selective activation of sub-codebooks based on channel conditions, rather than managing a single large codebook with all possible scenarios.
Solution Approach 2:
The system dynamically selects which sub-codebooks to use based on channel conditions, rank indicators, and transmission requirements. This dynamic adaptation allows the system to optimize between codebook size, feedback overhead, and accuracy in real-time, reducing unnecessary complexity while maintaining reliability when needed.
3Adaptability or versatility
If the codebook is designed to support multiple ranks and beam directions, then adaptability to different channel conditions improves, but the number of code words and feedback overhead increase
Solution Approach 1:
The codebook is segmented into sub-codebooks organized by different criteria (ranks, beam directions, spatial layers). This allows the system to provide adaptability to different channel conditions by selecting appropriate sub-codebooks, while avoiding the need to include all possible code words in a single monolithic codebook, thus controlling the total number of code words and feedback overhead.
Solution Approach 2:
The multi-sub-codebook structure provides universal adaptability across different transmission scenarios (different ranks, different beam directions, different channel conditions) through a unified framework. Each sub-codebook is designed to handle specific scenarios, and the system can universally adapt to various conditions by selecting the appropriate combination of sub-codebooks, avoiding the need for separate codebooks for each scenario.
Data Source
AI summary
The present invention discloses a method and terminal for feeding back channel status information, including: when the channel status information is fed back on the physical uplink control channel, code words contained in the used codebook CPUCCH (r) with a layer number or rank being r is a subset of the code words contained in the codebook CPUSCH (r) with a layer number or rank being r in the overall codebook defined in the LTE-A; wherein, the CPUCCH (r) is a single codebook or a single codebook equivalent to dual codebooks; and the CPUSCH (r) is a single codebook or a single codebook equivalent to the dual codebooks; and the single codebook equivalent to the dual codebooks means that the actually used codebook is an actually defined single codebook, however, 2 pre-coding matrix identifiers are required to determine the codebook of the code words therein for an established r. The method described by the present invention can ensure the precision of the PMI feedback under the limited overhead, make the CSI feedback on the PUCCH still be able to more effectively support the pre-coding technology and have good compatibility with the feedback on the PUSCH.