CSI-RS Orthogonalization for Interference Estimation
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Solution Overview
Problem
In LTE-A systems, achieving accurate orthogonalization among transmission antennas and cells is necessary for high-speed transmission and interference estimation, which existing technologies have not adequately addressed.
Innovation Solution
A radio base station apparatus and mobile terminal device configuration that generates and processes channel quality measurement reference signals to be non-orthogonal among cells and orthogonal among transmission antennas, using methods like time division multiplexing, frequency division multiplexing, and code division multiplexing, along with randomization techniques such as shifting and scrambling, to enable accurate interference estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channel quality measurement reference signals are made orthogonal among all cells, then interference estimation accuracy is improved, but device complexity and system overhead increase
Solution Approach 1:
The patent applies local quality by making reference signals orthogonal only within specific groups of cells (first and second cell groups) rather than across all cells uniformly. This localized orthogonalization approach maintains interference estimation accuracy within each group while reducing overall system complexity and overhead compared to universal orthogonalization.
Solution Approach 2:
The patent segments the cellular network into multiple cell groups (first cell group and second cell group) where orthogonalization is applied independently within each group. This segmentation allows the system to achieve good interference estimation within groups while avoiding the complexity of orthogonalizing all cells simultaneously.
2Productivity
If randomization processing is applied to make reference signals non-orthogonal among cells, then resource utilization is improved, but interference estimation accuracy deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the treatment of reference signals between within-cell-group and between-cell-group scenarios. Within each cell group, orthogonalization is maintained for accurate interference estimation, while between different cell groups, randomization is applied to improve resource utilization. This localized differentiation resolves the contradiction by applying the appropriate strategy in each context.
Data Source
Figure 1(a)~1(c)
Figure 2
Figure 3
AI summary
A mobile terminal device comprises a reception section configured to receive control information indicating resources in time and frequency domains to be used for channel state information reference signals, CSI-RSs, that are orthogonally-multiplexed among transmission antennas and a decoding section configured to decode a physical downlink shared channel that is mapped to resources that are not used for the CSI-RSs, which are determined based on the control information.