CSI Measurement Using Flexible Subframe Sets in LTE Cells
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Solution Overview
Problem
In LTE systems, the use of fixed paired spectrums in FDD and fixed uplink-downlink timeslot allocation in TDD fails to effectively support the dynamic asymmetry of uplink and downlink services, leading to reduced resource utilization due to cross timeslot interference between neighboring cells, which affects accurate CSI reporting and scheduling.
Innovation Solution
A method for measuring CSI by configuring different subframe sets based on uplink-downlink configurations in a target cell and neighboring cells, using network-side devices to determine and send configuration information to user equipment for accurate CSI measurement, including the use of CSI-RS and CSI-IM resources to account for varying interference types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple pieces of channel state information are fed back through all candidate precoding matrices, then the network side equipment can obtain complete channel state information for all precoding matrices, but the feedback overhead increases significantly
Solution Approach 1:
The patent extracts only the essential channel state information corresponding to the selected precoding matrix from the complete set of channel state information that would be obtained for all candidate precoding matrices. This selective extraction reduces feedback overhead while maintaining the precision needed for effective precoding, as only the most relevant channel state information is fed back to the network side equipment.
Solution Approach 2:
The patent segments the feedback process by dividing the set of precoding matrices into candidate precoding matrices and selected precoding matrices. Instead of feeding back channel state information for all matrices, the system segments the feedback to include only the selected subset, thereby reducing the quantity of feedback data while preserving measurement precision for the chosen precoding matrix.
2Quantity of substance
If channel state information is not fed back for all candidate precoding matrices, then the feedback overhead is reduced, but the network side equipment cannot obtain complete channel state information for precoding matrix indication
Solution Approach 1:
The patent applies preliminary action by having the terminal equipment select the optimal precoding matrix from candidate precoding matrices before feedback based on channel quality measurements. This preliminary selection ensures that the network side equipment receives channel state information for the most relevant precoding matrix, preventing information loss about the optimal precoding choice while reducing overall feedback overhead.
Solution Approach 2:
The patent introduces an intermediary selection mechanism where the terminal equipment acts as a mediator between the candidate precoding matrices and the feedback channel. The terminal selects the optimal precoding matrix based on channel conditions and feeds back only the corresponding channel state information, serving as an intermediary that filters and prioritizes information to reduce overhead while maintaining essential completeness.
3Measurement precision
If the terminal equipment selects optimal precoding matrix based on channel quality, then the precoding accuracy is improved, but the terminal equipment needs to measure and evaluate multiple candidate precoding matrices which increases processing complexity
Solution Approach 1:
The patent applies partial action by having the terminal equipment measure and evaluate only the necessary candidate precoding matrices required to identify the optimal one, rather than performing exhaustive analysis of all possible precoding matrices. This partial evaluation approach maintains precoding accuracy by selecting the optimal matrix from relevant candidates while reducing processing complexity through targeted rather than comprehensive measurement.
Data Source
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AI summary
Embodiments of the present invention provide a method for measuring channel state information CSI, a network-side device, and user equipment UE. The method includes: determining, by a network-side device, configuration information, where the configuration information is used to configure user equipment UE to perform CSI measurement on different subframe sets on a flexible frequency band or sub-bands of a flexible frequency band, the subframe sets are determined by the network-side device based on uplink-downlink configurations of subframes on the flexible frequency band or the sub-bands of the flexible frequency band in a target cell and at least one neighboring cell of the target cell, and the flexible frequency band is a frequency band on which a transmission direction is configurable; and sending, by the network-side device, the configuration information to the UE, so that the user equipment performs the CSI measurement based on the configuration information. By determining the different subframe sets on the flexible frequency band or the sub-bands of the flexible frequency band, the network-side device can obtain CSI measurement results corresponding to the different subframe sets, thereby obtaining CSI measurement results that are more accurate.