Codebook Subset Restriction Grouping for Signaling Overhead Reduction
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Solution Overview
Problem
The existing methods for codebook subset restriction in wireless communication systems, particularly with multiple antenna ports, result in significant signalling overhead due to the large size of the codebooks, especially in the LTE Rel-10 with 8 antenna ports, where each precoding matrix is mapped to 1-bit information using a bitmap approach.
Innovation Solution
The method involves grouping precoding matrices in codebooks at each rank with N antenna ports and identifying the state of each group as restricted or unrestricted by one bit, allowing for reduced signalling overhead by configuring higher-layer signalling to instruct User Equipment (UE) to report Precoding Matrix Indicators (PMI) and/or Rank Indicators (RI) based on the grouped codebook subset restriction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bitmap approach is used to restrict codebook subset with each precoding matrix mapped to 1-bit information, then the codebook subset restriction can be clearly indicated, but the signalling overhead becomes considerable
Solution Approach 1:
The codebook is divided into multiple subsets, and only the subset indicator needs to be signaled rather than individual bitmaps for each precoding matrix. This segmentation reduces the signaling overhead from 621 bits to a much smaller number of bits while maintaining the ability to restrict specific codebook subsets.
Solution Approach 2:
The invention extracts and signals only the essential subset indicator information rather than transmitting complete bitmap information for all precoding matrices. This extraction approach retains the necessary restriction functionality while eliminating redundant signaling data.
2Productivity
If the codebook size increases with more antenna ports (e.g., 8 antenna ports in Rel-10), then the system capacity and MIMO performance are improved, but the signalling overhead for codebook subset restriction becomes excessively large
Solution Approach 1:
The large codebook for 8 antenna ports is segmented into multiple manageable subsets. Instead of signaling 621 bits for the entire codebook, the system only needs to signal which subset to use, dramatically reducing overhead while supporting the full 8-antenna capability.
Solution Approach 2:
The invention introduces a new dimension of organization by grouping precoding matrices into subsets with specific properties. This additional organizational dimension allows efficient restriction signaling without being proportional to the total codebook size.
Data Source
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AI summary
The present invention discloses a method and device for processing codebook subset restriction, which includes: the codebooks for every rank ofN antenna ports are grouped, wherein N is a natural number; after grouping, the status of each group is identified as restricted or unrestricted by using one bit. The present invention can reduce the signaling overhead needed for codebook subset restriction.