Uplink Interference Measurement Resources in Flexible Wireless Systems
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Solution Overview
Problem
Current CSI reporting in wireless communication systems is not well-suited for flexible UL/DL subframes, as it fails to accurately reflect interference conditions, particularly due to the presence of UL-to-DL interference, which can vary rapidly and is not accounted for in fixed DL subframe CSI reports.
Innovation Solution
The introduction of Uplink Interference Measurement Resources (UL IMRs) allows for CSI measurements during UL subframes by creating 'holes' in UL resource elements, enabling separate interference measurement and channel estimation, even when flexible subframes are used for UL communication, and aligning UL IMRs with DL IMRs to facilitate accurate reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CSI reporting is performed in fixed DL subframes, then the reporting structure is simple and stable, but the interference conditions (particularly UL-to-DL interference) are not accurately reflected
Solution Approach 1:
The patent segments the measurement resources by introducing separate UL IMRs and DL IMRs. UL IMRs are configured in UL subframes to measure UL-to-DL interference, while DL IMRs measure DL interference. This segmentation allows accurate measurement of different interference types without requiring a complete redesign of the measurement framework.
Solution Approach 2:
The patent introduces IMRs as intermediary measurement resources that mediate between the physical interference conditions and the CSI reporting mechanism. These IMRs serve as dedicated probe signals that isolate and measure interference components, enabling the CSI report to accurately reflect actual interference conditions without directly modifying the existing CSI reporting structure.
2Adaptability or versatility
If flexible UL/DL subframes are used for traffic adaptation, then system flexibility and traffic handling improve, but accurate CSI measurement becomes difficult due to varying interference conditions
Solution Approach 1:
The patent makes the measurement resource configuration dynamic by allowing UL IMRs to be configured in flexible subframes that can switch between UL and DL directions. The eNB configures UL IMRs in UL subframes and DL IMRs in DL subframes according to the actual flexible UL-DL configuration, enabling accurate interference measurement that adapts to changing traffic conditions while maintaining measurement precision.
Solution Approach 2:
The patent changes the configuration parameters of measurement resources based on traffic conditions. The eNB configures different IMR resources and their associations with flexible subframes according to the actual UL-DL configuration and traffic requirements, allowing the measurement system to adapt its parameters (which IMRs to use, in which subframes) to maintain accuracy under flexible operation.
3Measurement precision
If separate CSI reporting for flexible subframes is implemented, then interference accuracy improves, but signaling overhead and complexity increase
Solution Approach 1:
The patent makes the existing CSI reporting mechanism universal by extending it to handle both fixed and flexible subframes through the IMR framework. The same CSI reporting structure is used, but with enhanced IMR-based interference measurement capabilities that work for both fixed and flexible configurations, avoiding the need for separate reporting mechanisms and reducing signaling overhead.
Data Source
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AI summary
Channel state information is generated by a communication device. The device can determine that at least one uplink resource element of a radio frame is to be left unoccupied and perform at least one interference measurement on at least one downlink resource element coinciding with the at least one unoccupied uplink resource element, A channel state information report can then be generated based on the measurement, A network node may cause the communication device to leave at feast one uplink resource element of a radio frame unoccupied.