CSI-RS Interference Measurement in 5G NR Systems
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Solution Overview
Problem
In 5G NR systems, existing interference measurement methods using periodic zero-power CSI-RS are inefficient for MU-MIMO scenarios, leading to inaccurate intra-cell interference estimation and degraded link adaptation performance due to dynamic scheduling decisions.
Innovation Solution
Configuring periodic, semi-persistent, or aperiodic IM resources based on CSI-RS with reduced periodicity (e.g., 1 slot) and indicating IMR positions in both time and frequency domains, allowing for more robust and accurate interference measurement, and using NZP CSI-RS for intra-cell interference measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic zero-power CSI-RS is used for interference measurement, then interference measurement can be performed, but measurement accuracy is insufficient for MU-MIMO scenarios due to dynamic scheduling decisions
Solution Approach 1:
The patent changes the parameters of CSI-RS resources by introducing multiple types (NZP CSI-RS and ZP CSI-RS) with different configurations and periodicities. NZP CSI-RS provides actual signal measurements while ZP CSI-RS provides interference measurements, allowing the system to adapt measurement parameters dynamically for improved accuracy in MU-MIMO scenarios.
Solution Approach 2:
The patent segments the interference measurement process by separating channel measurement (using NZP CSI-RS) from interference measurement (using ZP CSI-RS). This segmentation allows independent optimization of each measurement type, with ZP CSI-RS specifically configured to measure interference from other UEs in MU-MIMO transmissions.
2Measurement precision
If beam forming is used to compensate path loss, then signal to noise ratio is improved, but beam switching complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple CSI-RS resources with different beam directions and measurement settings. The UE is provided with ahead-of-time information about available beams and their associated CSI-RS resources, allowing it to prepare measurement configurations in advance and reduce complex real-time beam switching decisions.
3Reliability
If interference measurement resources are configured with reduced periodicity, then measurement robustness is improved, but signaling overhead increases
Solution Approach 1:
The patent applies universality by designing CSI-RS resources that serve multiple functions: NZP CSI-RS is used for both channel measurement and reference signal transmission, while ZP CSI-RS is used for interference measurement. This multi-functionality reduces the need for separate dedicated resources, thereby reducing overall signaling overhead while maintaining robust measurement capabilities.
Data Source
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AI summary
This disclosure provides a method, apparatus and computer readable medium that facilitate configuring an interference measurement (IM) resource of a user equipment (UE), wherein the IM resource is based on channel state information (CSI)-reference signal (RS), CSI-RS, wherein the CSI-RS is a zero power CSI-RS (ZP CSI-RS) or a non-zero power CSI-RS (NZP CSI-RS). The UE assumes the same Rx beam to be used for both, interference measurement and channel measurement. If the time offset between a downlink control information (DCI) and CSI-RS is smaller than a threshold, the UE applies a default spatial assumption for interference measurement, and if the time offset is larger than certain threshold, the UE applies the Rx beam as indicated by the DCI for interference measurement..