Precoding Matrix Indicator Determination for Active Antenna Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MIMO wireless systems face challenges in achieving optimal precoding due to limited vertical beam control and interference management in active antenna systems, particularly with cell splitting, which affects system capacity and CSI feedback accuracy.
Innovation Solution
The method involves user equipment determining intermediate matrices based on reference signal sets from a base station, allowing for dynamic beam scheduling and optimizing precoding matrices by using block diagonal matrices with kronecker products of matrices C and D, which are functions of intermediate matrices, to improve beam alignment and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional base station antennas with fixed downtilt are used, then system cost is reduced, but vertical beam control flexibility is limited
Solution Approach 1:
The patent replaces the mechanical/physical fixed downtilt adjustment mechanism with a digital signal processing approach using precoding matrices. The base station applies precoding matrices to electronically control beam directions in the vertical dimension without physically adjusting antenna tilts, thus achieving flexible vertical beam control while maintaining simple antenna hardware.
Solution Approach 2:
The patent changes the control parameter from fixed physical downtilt angles to dynamic precoding matrix coefficients. By varying the precoding matrix parameters based on channel state information, the system can dynamically adjust vertical beam directions to match user equipment positions, achieving adaptability without increasing hardware complexity.
2Productivity
If cell splitting is implemented to increase system capacity, then system capacity is improved, but interference management becomes more difficult
Solution Approach 1:
The patent applies different precoding matrices to different spatial regions and user equipment. Each user receives a customized precoding matrix optimized for its specific channel conditions and location. This localized optimization allows cell splitting to increase capacity while managing interference by directing beams precisely to intended recipients rather than using broad omnidirectional coverage.
Solution Approach 2:
The patent implements a feedback mechanism where user equipment measures channel quality and feeds back CSI (Channel State Information) to the base station. The base station uses this feedback to select and apply appropriate precoding matrices from codebooks, enabling dynamic interference management in split-cell configurations by continuously adapting beams to current channel conditions.
3Measurement precision
If CSI quantization feedback is used, then implementation complexity is reduced, but CSI feedback accuracy deteriorates
Solution Approach 1:
The patent segments the precoding matrix selection into two independent parts: horizontal dimension (first codebook) and vertical dimension (second codebook). The CSI feedback is similarly segmented into two separate PMI indicators. This segmentation allows each dimension to be quantized independently with appropriate precision, achieving accurate 3D beam control while keeping individual feedback payloads manageable in size.
4Adaptability or versatility
If dual codebooks are designed for 8-antenna systems, then precoding flexibility is improved, but codebook design complexity increases
Solution Approach 1:
The patent extends the conventional 2D precoding (horizontal only) to 3D precoding by adding the vertical dimension through a second codebook. The dual codebook structure allows independent control of horizontal and vertical beamforming, providing full 3D spatial flexibility. The Kronecker product combination of the two codebooks systematically generates comprehensive precoding options without requiring exhaustive enumeration of all possible 3D beam configurations.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides a method for determining a precoding matrix indicator, user equipment, and a base station. The method includes: receiving a first reference signal set sent by a base station; determining, based on the first reference signal set, one or more intermediate matrices, and reporting, to the base station, a first index used to indicate the intermediate matrix; receiving a second reference signal set sent by the base station; and determining, based on the second reference signal set, a precoding matrix, and reporting, to the base station, a precoding matrix indicator used to indicate the precoding matrix, where the precoding matrix is a product W of two matrices W1 and W2, and W=W1W2, where W1 is a block diagonal matrix, W1=diag{X1,X2}, a block matrix Xi is a kronecker product of two matrices Ci and Di, Xi=Ci⊗Di, i=1,2, and the matrix Ci or the matrix Di is a function of the one or more intermediate matrices. In this way, transmission performance of an active antenna system can be improved.