LTE-A Codebook Subset Restriction for Feedback Complexity
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Solution Overview
Problem
In wireless communication systems, particularly in LTE-A, the receiving end faces high calculation complexity and incorrect code word selection due to large codebook sizes, leading to increased signaling overhead and errors in channel information feedback.
Innovation Solution
Implementing code word restriction by the transmitting end to define a subset of code words for both codebooks, reducing the number of code words to be considered, and informing the receiving end through high-layer signaling, thereby reducing calculation complexity and incorrect selections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the codebook size is increased to improve feedback accuracy and channel information quality, then the reliability of channel information feedback is improved, but the calculation complexity at the receiving end increases and incorrect code word selection occurs more frequently
Solution Approach 1:
The patent divides the large codebook into multiple code word subsets. The receiving end is configured to select code words only from a specific subset rather than traversing the entire codebook. This segmentation reduces the search space and calculation complexity while maintaining feedback accuracy through selective subset optimization.
Solution Approach 2:
Different code word subsets are configured for different codebooks (first codebook and second codebook) with different properties. The receiving end applies different selection criteria and traversal strategies to different subsets, optimizing the local quality of code word selection for each subset rather than using a uniform approach across the entire codebook.
2Reliability
If the codebook size is increased to improve feedback accuracy, then the reliability of channel information feedback is improved, but the time required for code word selection increases
Solution Approach 1:
By segmenting the codebook into subsets and configuring the receiving end to search only within specific subsets, the patent significantly reduces the time required for code word selection. The receiving end avoids traversing the entire large codebook and instead focuses computation on relevant subsets, reducing selection time while maintaining accuracy.
Solution Approach 2:
The code word subsets are pre-configured and communicated to the receiving end through higher-layer signaling before the actual code word selection process. This preliminary configuration allows the receiving end to prepare the search space in advance, avoiding the need to traverse the entire codebook during real-time operation.
3Ease of operation
If code word restriction is applied to reduce calculation complexity, then the ease of operation at the receiving end is improved, but the adaptability of the codebook to different channel conditions may be reduced
Solution Approach 1:
The patent enables dynamic configuration of code word subsets through higher-layer signaling, allowing the system to adapt the subset configuration to different channel conditions and transmission scenarios. The receiving end can be reconfigured with different subsets based on current channel characteristics, maintaining adaptability while preserving the computational benefits of restriction.
Solution Approach 2:
The code word subset configuration mechanism serves multiple functions: it reduces calculation complexity, enables adaptability to different channel conditions through reconfigurable subsets, and maintains compatibility with existing LTE-A feedback structures. The same subset configuration approach can be applied to different codebooks and transmission modes.
Data Source
Figure 1~2
AI summary
The present invention discloses a method, device and system for configuring codebooks. The method comprises a transmitting end selecting a code word restricted sub-set and informing a receiving end of the code word restricted sub-set, the code word restricted sub-set containing part or all of code words in a first codebook and/or a second codebook; and the receiving end selecting an optimal pre-coded code word from the code word restricted sub-set and informing the transmitting end of an index of the optimal pre-coded code word. By the present invention, code word restriction is implemented in the case of dual codebooks in the LTE-A system such that the calculation complexity is reduced when the receiving end selects the code word, occurrences of the case where the receiving end selects the code word wrongly are decreased, and the signaling structure in the LTE system can be inherited very well.