Codebook Subset Restriction Signaling for Lower Feedback Overhead
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Solution Overview
Problem
The existing methods for signaling codebook subset restrictions in wireless communication systems face high overhead due to the need for bitmaps that individually restrict each precoder, especially in large antenna arrays and multi-dimensional scenarios, leading to inefficient use of feedback resources.
Innovation Solution
A method that generates codebook subset restriction signaling by jointly restricting precoders within groups based on common components, such as beam precoders, using bit patterns that depend on reference configurations, reducing the number of bits required for signaling by exploiting correlations and probabilities of configuration usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual bitmap restriction is used for each precoder, then precise control of codebook subset restrictions is achieved, but signaling overhead increases significantly
Solution Approach 1:
The patent merges multiple individual precoder restriction indicators into a single joint restriction signal. Instead of sending separate bitmap entries for each precoder, the invention groups precoders and uses a single signaling mechanism to restrict multiple precoders simultaneously, thereby reducing signaling overhead while maintaining restriction precision.
Solution Approach 2:
The patent segments the codebook into groups of precoders with similar characteristics (e.g., same beam precoder). By segmenting precoders based on common components, the system can apply joint restriction to entire groups using fewer signals, reducing the overall signaling overhead compared to individual precoder restriction.
2Reliability
If large codebook size is used, then better matching of channel conditions is achieved, but feedback resource consumption increases
Solution Approach 1:
The patent applies partial action by restricting only certain subsets of precoders that are less likely to be optimal, rather than restricting the entire codebook. This allows the system to maintain a large codebook for good channel matching performance while using joint restriction signals to selectively disable specific precoder groups, thereby managing feedback resources efficiently.
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.