CSI Feedback Overhead Reduction in Massive MIMO Codebook Design
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Solution Overview
Problem
Current channel state information (CSI) feedback mechanisms in Massive MIMO systems, particularly in NR, face challenges in reducing signaling overheads due to the need to report a large number of beam superposition coefficients, which is not efficiently managed by existing codebook designs.
Innovation Solution
The proposed method reduces feedback overheads by generating and using codebook indication information that includes fewer pieces of beam information for each transport layer, allowing the receive-end device to construct precoding vectors using a reduced set of beam information, thereby minimizing the number of beam superposition coefficients fed back.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a plurality of beam superposition coefficients are reported for each transport layer in NR Massive MIMO, then the accuracy of channel state information is improved, but the feedback overhead increases significantly
Solution Approach 1:
The patent extracts and reports only the necessary beam superposition coefficients rather than all possible coefficients. Specifically, it identifies and reports only those coefficients that are essential for reconstructing the precoding matrix, thereby reducing feedback overhead while maintaining channel state information accuracy.
Solution Approach 2:
The patent segments the feedback process into two parts: W1 matrix indicating beam directions and W2 matrix indicating beam superposition coefficients. This segmentation allows the system to separately optimize the feedback of beam selection information and beam combination information, reducing overall feedback overhead.
2Loss of information
If all beams are reported for each transport layer, then the completeness of CSI feedback is improved, but the signaling overhead increases
Solution Approach 1:
The patent applies partial action by reporting only a subset of beam superposition coefficients rather than all possible coefficients. It identifies the minimum necessary set of coefficients required to reconstruct the precoding matrix accurately, avoiding the overhead of reporting redundant information.
Solution Approach 2:
The patent changes the parameter representation by using a compact indexing scheme for beam superposition coefficients. Instead of reporting all coefficients explicitly, it uses index values that reference pre-defined codebook entries, thereby reducing the number of bits required for feedback.
3Quantity of substance
If the number of reported beams is reduced to 1 beam in one polarization, then the feedback overhead is reduced, but the channel state information accuracy deteriorates
Solution Approach 1:
The patent merges the feedback of multiple beams across different polarizations into a unified codebook structure. By combining beam information from both polarizations in the W1 matrix and their superposition coefficients in the W2 matrix, it achieves accurate CSI feedback with reduced overhead compared to reporting all beams separately.
Data Source
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AI summary
Embodiments of this application disclose channel state information feedback and receiving methods, a transmit-end device and a receive-end device, and relate to the field of communications technologies. The method includes: generating and sending, by a transmit-end device, codebook indication information of K transport layers, where K is an integer greater than or equal to 2; the codebook indication information includes: L pieces of beam information used by the K transport layers, and indication information used to indicate beam information associated with each of the K transport layers; L is an integer greater than or equal to 2, and a quantity of pieces of beam information associated with at least one of the K transport layers is less than L. Implementing a channel state information feedback and receiving technology provided in this application helps reduce feedback overheads of channel state information.