Codebook Subset Restriction Signaling With Grouped Precoder Compression
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Solution Overview
Problem
The conventional method of signaling codebook subset restrictions in wireless communication systems is inefficient, particularly for large antenna arrays and two-dimensional antenna arrays, due to high overhead caused by the need to signal each precoder individually, which increases the number of bits required and can lead to excessive signaling overhead.
Innovation Solution
The proposed solution involves using explicit or implicit assumptions about which sets of precoders are more likely to be restricted, allowing for the use of reference configurations to reduce the number of bits needed for signaling by representing more probable configurations with shorter bit patterns and less probable configurations with longer patterns, thereby compressing the signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bitmap of length N is used to signal codebook subset restriction for each precoder individually, then full flexibility to restrict every possible subset of the codebook is achieved, but signaling overhead becomes excessively large for large antenna arrays
Solution Approach 1:
The codebook is divided into multiple groups, and restriction configurations are defined per group rather than for individual precoders. This segmentation allows the system to manage large codebooks efficiently by applying restrictions at the group level, reducing the number of bits required while maintaining adequate control flexibility.
Solution Approach 2:
Instead of providing full individual control over every precoder, the invention applies partial control by restricting entire groups of precoders simultaneously. This partial action approach is sufficient for most practical scenarios where interference management requires blocking specific spatial directions, without needing to control each precoder individually.
2Measurement precision
If a large codebook with many elements is used by default, then spatial resolution is improved for UE separation in MU-MIMO operation, but the number of bits required to signal codebook subset restriction increases
Solution Approach 1:
The large codebook is segmented into multiple groups, allowing the system to maintain the large codebook size for fine spatial resolution while applying restriction configurations at the group level. This segmentation enables efficient signaling by representing restrictions as group-level patterns rather than individual precoder specifications.
Solution Approach 2:
The invention introduces a group dimension to the codebook structure, organizing precoders into groups that can be collectively restricted. This additional organizational dimension allows the system to manage large codebooks efficiently by operating at the group level rather than the individual precoder level.
Data Source
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AI summary
A network node (10) signals to a wireless communication device (14) which precoders in a codebook are restricted from being used. The network node (10) 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 (10) sends the generated signaling to the wireless communication device (14).