Precoding Matrix Segmentation for 3D MIMO Resource Selection
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Solution Overview
Problem
In the context of LTE-A systems, mechanism 2 for CSI reporting in three-dimensional MIMO lacks an effective method for selecting candidate reference signal resources due to the unknown precoding matrix, which complicates beam or resource selection.
Innovation Solution
A method is introduced where a channel state information (CSI) process is configured for K reference signal resources or antenna port groups, allowing the selection of a precoding matrix based on a preset matrix set related to the quantity of resources and beams to be selected, with the precoding matrix split into constituent parts for beam selection and phase modulation, simplifying the design and storage of the precoding matrix set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanism 2 for CSI reporting is used in three-dimensional MIMO, then CSI feedback accuracy is improved, but the complexity of beam or resource selection increases due to unknown precoding matrix
Solution Approach 1:
The precoding matrix W is segmented into two independent parts: W1 for beam selection and W2 for phase modulation. This segmentation allows the UE to perform beam selection based on W1 without needing to know the complete precoding matrix, thereby reducing selection complexity while maintaining CSI feedback accuracy through the combined effect of W1 and W2.
Solution Approach 2:
The beam selection function is extracted from the complete precoding matrix by using only W1 for beam selection decisions. The UE measures reference signals and selects beams based on W1 alone, while the complete precoding matrix W = W1 × W2 is used for actual transmission. This extraction simplifies the selection process by removing the need to know W2 during beam selection.
2Measurement precision
If multiple sets of precoded candidate reference signal resources are sent to UE for selection, then CSI feedback accuracy is improved, but feedback overhead increases due to extra selection reporting
Solution Approach 1:
The feedback is segmented into two parts: beam selection information based on W1 and precoding information based on W2. The UE reports beam selection indices corresponding to W1 configurations, which requires fewer bits than reporting complete precoding matrix information. The base station then uses this beam selection information combined with its own W2 configuration to determine the complete precoding matrix, thereby reducing feedback overhead while maintaining accuracy.
3Ease of operation
If beam selection is directly bound to rank as in mechanism 1, then selection process is simplified, but adaptability to mechanism 2 with unknown precoding matrix is reduced
Solution Approach 1:
The selection process is segmented into two independent stages: beam selection based on W1 and precoding selection based on W2. The UE performs beam selection using only W1 information, which is independent of the rank. The rank then determines the selection of W2 from a codebook. This segmentation maintains operational simplicity by separating beam selection from rank-dependent precoding selection, while adapting to mechanism 2 by allowing W1 and W2 to be configured independently.
Solution Approach 2:
The system dynamically adapts the precoding matrix configuration based on rank indicators. The W1 matrix configuration remains relatively static for beam selection, while W2 is dynamically selected from codebooks based on the determined rank. This dynamic approach allows the system to maintain simple beam selection procedures while adapting to different transmission ranks and channel conditions in mechanism 2.
Data Source
AI summary
The present disclosure includes example resource selection methods and apparatuses. The example method includes configuring a CSI process for a second device, where the CSI process corresponds to configuration information of K reference signal resources or configuration information of K reference signal antenna port groups. A reference signal is sent to the second device according to the configuration information corresponding to the CSI process, so that the second device obtains a corresponding channel quality measurement result by measuring the reference signal, where the channel quality measurement result includes a precoding matrix indicator (PMI). The PMI is used to indicate a serial number of a precoding matrix selected by the second device, and the selected precoding matrix is a matrix in a preset precoding matrix set, where the preset precoding matrix set is determined according to K and a quantity T of beams to be selected.