Codebook Subset Restriction Signaling for Low-Overhead Precoder Groups
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Solution Overview
Problem
The conventional method of signaling codebook subset restriction using a bitmap for each precoder in a large antenna array system results in high overhead, especially when the codebook subset restriction is frequently updated or when serving multiple users, due to the quadratic increase in codebook size for two-dimensional antenna arrays.
Innovation Solution
A method for signaling codebook subset restriction that jointly restricts precoders in groups by using a common component, such as beam precoders, and employs a bit pattern that varies in length based on the likelihood of configuration usage, 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 in a large antenna array system, then the restriction configuration can be flexibly configured, but the signaling overhead increases significantly
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 reduces the number of bits required for signaling while maintaining configurable flexibility through group-based restriction patterns.
Solution Approach 2:
Instead of providing full individual control over each precoder, the invention applies partial control at the group level. This partial action approach reduces signaling overhead significantly while still providing sufficient flexibility for most practical scenarios through group-based restriction configurations.
2Reliability
If the codebook size is increased to support two-dimensional antenna arrays, then the precoding performance is improved, but the signaling overhead for codebook subset restriction increases quadratically
Solution Approach 1:
The large codebook for two-dimensional antenna arrays is segmented into multiple smaller groups. This allows the system to maintain the large overall codebook size for good precoding performance while applying restriction configurations at the group level, reducing the quadratic growth of signaling overhead.
Solution Approach 2:
The invention introduces a new dimension of organization by grouping precoders based on spatial relationships (e.g., angular intervals, beam groups). This additional organizational dimension allows efficient restriction signaling that scales better than the quadratic growth of traditional bitmap approaches.
3Adaptability or versatility
If codebook subset restriction is frequently updated to adapt to changing channel conditions, then the system adaptability is improved, but the signaling overhead and frequency resource consumption increase
Solution Approach 1:
The invention enables dynamic codebook subset restriction updates through efficient group-based signaling. The reduced bit requirement allows frequent updates of restriction configurations to track changing channel conditions without consuming excessive signaling resources.
Solution Approach 2:
The group-based restriction configuration can be updated periodically or event-driven based on channel condition changes. The reduced signaling overhead enables more frequent periodic updates or event-triggered updates without excessive resource consumption.
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.