Precoding Matrix Feedback Overhead Reduction via Codebook Segmentation
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Solution Overview
Problem
In MIMO wireless communication systems, the high feedback overheads associated with indicating precoding vectors for spatial multiplexing streams pose a challenge, particularly when a large number of spatial streams are involved.
Innovation Solution
The method involves determining a precoding matrix by selecting component matrices and their weights based on a basic codebook, where each component matrix's dimension matches the ideal precoding matrix, and only the component matrices and their weights are fed back, reducing the feedback overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each precoding vector is indicated separately for spatial multiplexing streams, then the precoding can be accurately performed, but the feedback overhead becomes excessively high when there are many spatial streams
Solution Approach 1:
The precoding matrix is segmented into multiple codebooks, where each codebook contains a subset of precoding vectors. Instead of indicating all precoding vectors separately, the system indicates which codebooks are used and selects specific vectors from those codebooks, thereby reducing feedback overhead while maintaining precoding accuracy.
Solution Approach 2:
Multiple codebooks are merged to form a comprehensive precoding matrix. The system combines information from multiple codebooks (each containing precoding vectors) to reconstruct the full precoding matrix, reducing the total feedback overhead compared to indicating every vector individually while preserving the necessary precoding information.
2Productivity
If a large number of spatial streams are used to increase transmission throughput, then the system capacity improves, but the feedback overhead for indicating precoding vectors increases proportionally
Solution Approach 1:
The codebook is segmented into multiple subsets, each containing precoding vectors for specific spatial streams. The system indicates which segments are active and selects vectors from appropriate segments, enabling support for many spatial streams without linearly increasing feedback overhead.
Solution Approach 2:
Instead of indicating all possible precoding vectors for all spatial streams, the system uses partial indication by specifying only the active codebooks and selected vectors. This partial action approach reduces feedback overhead while still providing sufficient information for accurate precoding of the actual spatial streams being transmitted.
Data Source
AI summary
Embodiments can provide a precoding matrix indicating method, a precoding matrix determining method, a receive end device, and a transmit end device. In the precoding matrix indicating method, component matrices of an ideal precoding matrix and a weight of each component matrix can be determined based on at least one basic codebook. A dimension of each component matrix is the same as a dimension of the ideal precoding matrix, and a column vector of each component matrix is selected from column vectors of one of the at least one basic codebook. A precoding matrix indicator can be sent. The precoding matrix indicator can indicate the component matrices and the weight of each component matrix. With this, an ideal precoding matrix is approximately represented in a form of a weighted sum of a plurality of component matrices so that feedback overheads caused by feeding back a precoding matrix can be reduced.