Multilevel Codebook Indexing for Precoding Signaling Overhead Reduction
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Solution Overview
Problem
As the number of antennas in user equipment increases, the size of the precoding codebook grows, leading to increased signaling overheads due to the need for more bits in control signaling to transmit precoding indexes, which affects transmission efficiency in high-frequency bands.
Innovation Solution
A method is introduced where user equipment receives a multilevel control signaling to determine a multilevel codebook index, which is used to obtain a target precoding matrix by performing predetermined matrix operations on precoding matrices corresponding to the codebook indexes of different levels, reducing the number of bits required for signaling and thus minimizing overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of transmitting antennas in user equipment increases, then the capability for high-frequency band transmission is improved, but the size of the precoding codebook increases, leading to increased signaling overheads
Solution Approach 1:
The precoding codebook is segmented into multiple subcodebooks, each corresponding to a specific antenna port configuration. Instead of using a single large codebook that requires many bits for indexing, the system divides the codebook into smaller manageable subcodebooks (e.g., first subcodebook for 2 antenna ports, second subcodebook for 4 antenna ports). This segmentation reduces the number of bits required to indicate the precoding matrix index while maintaining support for multiple antenna configurations.
Solution Approach 2:
The patent introduces a hierarchical structure to the codebook indexing by adding a subcodebook indication dimension. Instead of a flat single-level index, the system uses a two-dimensional indexing approach: first indicating which subcodebook to use (based on antenna port configuration), then indicating the specific precoding matrix within that subcodebook. This dimensional change allows efficient indexing of a large overall codebook space using fewer total bits.
2Measurement precision
If more bits are used in control signaling to transmit precoding indexes, then the precision of precoding indication is improved, but the signaling overhead increases, affecting transmission efficiency
Solution Approach 1:
The control signaling is segmented into multiple parts: a subcodebook indication field and a precoding matrix index field within the selected subcodebook. This segmentation allows the system to achieve precise precoding indication by combining information from both fields, while keeping each individual field compact. The total number of bits required is optimized by adapting the size of each field based on the selected subcodebook configuration.
Solution Approach 2:
The system dynamically adapts the codebook structure and signaling format based on the antenna port configuration. When the number of antenna ports changes, the system dynamically selects the appropriate subcodebook and adjusts the signaling fields accordingly. This dynamic adaptation ensures that the signaling overhead is minimized for each specific configuration while maintaining precise precoding indication.
Data Source
AI summary
A method for indicating precoding information, user equipment (UE) and an access network entity are provided according to the disclosure. The method includes: receiving, by a user equipment (UE), a control signaling transmitted by an access network entity; determining, by the UE, a multilevel codebook index in response to the control signaling; and determining, by the UE, a target precoding matrix based on the multilevel codebook index and a multilevel codebook obtained in advance.