HARQ Codebook Generation for Reduced Bit Overhead
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Solution Overview
Problem
In the LTE and NR systems, the existing method of performing HARQ feedback using CBG-based feedback results in over-dimensioned feedback bits, leading to inefficient resource utilization and increased signaling overhead, especially when dealing with multiple TBs per PDSCH.
Innovation Solution
A method is introduced to generate a HARQ codebook using N bits per PDSCH, where N is the maximum value of CBGs corresponding to the PDSCHs, rather than the maximum value of CBGs corresponding to TBs, thereby adapting to different TB configurations and reducing bit overhead and improving resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback is performed using the maximum value of numbers of CBGs configured for each TB across all serving cells, then coverage and reliability are improved, but bit overhead increases and resource utilization deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the feedback mechanism between CBG-based and TB-based HARQ feedback. For CBG-based feedback, it uses the maximum number of CBGs per TB (M) to determine codebook size, while for TB-based feedback, it uses the actual number of TBs (L). This localized adaptation ensures each feedback type uses the appropriate dimension, reducing overall bit overhead while maintaining reliability for both feedback modes.
Solution Approach 2:
The patent changes the parameter used for codebook size determination based on the feedback type. Instead of always using the maximum CBGs per TB, it dynamically selects between using M (maximum CBGs per TB) for CBG-based feedback and L (actual number of TBs) for TB-based feedback. This parameter change resolves the contradiction by adapting the codebook dimension to the specific feedback requirement.
2Adaptability or versatility
If the number of feedback bits is increased to cover all possible CBG configurations, then adaptability is improved, but resource utilization deteriorates
Solution Approach 1:
The patent applies local quality by creating different codebook structures for different feedback scenarios. For CBG-based HARQ feedback, it generates a codebook with M bits to accommodate all CBG configurations. For TB-based feedback, it generates a codebook with L bits matching the actual TB count. This localized optimization ensures adaptability for each feedback type without unnecessarily increasing resources for scenarios where it's not needed.
Solution Approach 2:
The patent uses partial action by generating codebooks with the minimum necessary bits for each feedback type. Instead of always using the maximum possible bits to cover all scenarios, it uses exactly M bits for CBG-based feedback and L bits for TB-based feedback. This partial approach provides sufficient adaptability for each specific case without the excessive resource consumption of a universal maximum-size codebook.
3Measurement precision
If HARQ feedback is performed on each TB with multiple bits per TB, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by differentiating the codebook generation process based on the feedback type. For CBG-based feedback, it generates a codebook with M bits providing fine-grained feedback precision. For TB-based feedback, it generates a codebook with L bits. The terminal device applies different generation rules locally depending on the feedback type, maintaining high precision where needed while simplifying the process where appropriate.
Solution Approach 2:
The patent introduces dynamics by making the codebook generation rule adaptable based on the feedback type. The network can dynamically indicate whether CBG-based or TB-based feedback should be used, and the terminal adjusts its codebook generation accordingly. This dynamic approach allows the system to optimize between precision and complexity based on actual channel conditions and requirements.
Data Source
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AI summary
A method for generating a hybrid automatic repeat request codebook, a user equipment and a medium; the method comprises: receiving a PDSCH transport block; with regard to a service cell starting a code block group-based feedback HARQ function, using N bits to generate an HARQ codebook corresponding to the transport block, wherein N is the maximum value of the number of code block groups corresponding to each PDSCH. In applying the foregoing solution, the problem of greater numbers of configured code block groups caused by adapting number parameters of different transport blocks is prevented, thereby reducing bit overhead when performing code block group-based HARQ feedback and improving the utilization ratio of resources.