Codebook Subset Restriction Signaling With Grouped Precoder Control
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Solution Overview
Problem
The conventional method of signaling codebook subset restriction using a bitmap for each precoder results in high overhead, especially for large antenna arrays and frequent updates, particularly in scenarios with many users.
Innovation Solution
A method for signaling codebook subset restriction that jointly restricts precoders in groups by a common component, using a bit pattern that depends on the likelihood of configuration matches, reducing the number of bits required for signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bitmap is used to signal codebook subset restriction for each precoder, then full flexibility in restricting precoders is achieved, but signaling overhead becomes very high
Solution Approach 1:
The codebook is divided into multiple groups, and restriction configurations are applied at the group level rather than individual precoder level. This segmentation allows the system to manage large codebooks efficiently by treating groups of precoders as units, reducing the number of bits needed to signal restrictions while maintaining configurable flexibility across different codebook portions.
Solution Approach 2:
Instead of signaling restriction status for every single precoder in the codebook, the invention signals restrictions for groups of precoders. This partial action approach applies restriction configurations to subsets of the full codebook, significantly reducing signaling overhead while still providing adequate control over precoder selection for different transmission scenarios.
2Reliability
If codebook size is increased to better match channel conditions, then precoding performance improves, but feedback channel capacity requirements increase
Solution Approach 1:
The codebook is segmented into multiple groups that can be independently configured and restricted. This allows the system to maintain a large overall codebook for high performance while only signaling restrictions for specific groups that are relevant to current channel conditions, thereby reducing feedback overhead while preserving precoding accuracy.
Solution Approach 2:
Different restriction configurations can be applied to different groups of precoders based on local channel conditions and transmission requirements. This local quality approach allows the system to optimize precoder selection for specific spatial or angular regions while maintaining overall codebook flexibility, matching feedback signaling to actual performance needs rather than uniformly restricting entire codebooks.
Data Source
AI summary
A network node signals to a wireless communication device which precoders in a codebook are restricted from being used. The network node in this regard generates codebook subset restriction signaling that, for each of one or more groups of precoders, jointly restricts the precoders in the group by restricting a certain component (e.g., a certain beam precoder) that the precoders in the group have in common. This signaling may be for instance rank-agnostic signaling that jointly restricts the precoders in a group without regard to the precoders' transmission rank. Regardless, the network node sends the generated signaling to the wireless communication device.