CSI Feedback for Single DCI Multi-TRP Transmission
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Solution Overview
Problem
In New Radio (NR) systems, existing methods for Channel State Information (CSI) feedback are inadequate for Non-Coherent Joint Transmission (NC-JT) from multiple Transmission/Reception Points (TRPs), particularly in handling interference measurements and reporting overhead, which affects scheduling flexibility and accuracy.
Innovation Solution
A method for CSI feedback in NR systems involves configuring User Equipment (UE) with multiple NZP CSI-RS and CSI-IM resources for channel and interference measurement, allowing the UE to compute and report NC-JT CSI, single TRP CSI, or combined reports based on interference scenarios, optimizing interference measurement and reducing feedback overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple CSI-IM resources are configured for interference measurement in NC-JT, then interference measurement accuracy is improved, but CSI feedback overhead increases
Solution Approach 1:
The patent segments the interference measurement process by configuring multiple CSI-IM resources (first CSI-IM resource and second CSI-IM resource) that can be separately measured and reported. This allows the UE to provide detailed interference information for different TRPs or transmission scenarios while maintaining structured feedback format to control overhead.
Solution Approach 2:
The patent introduces a new dimension to CSI feedback by adding interference measurement results from multiple CSI-IM resources to the existing CSI report structure. This enables the network to obtain both channel state information and interference information in a unified feedback mechanism, improving overall scheduling accuracy without requiring separate feedback channels.
2Measurement precision
If multiple NZP CSI-RS resources are configured for channel measurement, then channel measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent segments channel measurement into multiple NZP CSI-RS resources, each associated with different TRPs or transmission points. The UE measures channels separately for each resource and combines the results to compute CSI for NC-JT scenarios, improving measurement accuracy while maintaining manageable complexity through structured processing.
Solution Approach 2:
The NZP CSI-RS resources are designed to serve multiple functions: they can be used for channel measurement, interference measurement (when combined with CSI-IM resources), and CSI computation for both single-TRP and multi-TRP scenarios. This multi-functionality reduces the need for separate signaling for different measurement purposes.
3Adaptability or versatility
If NC-JT CSI reporting is implemented, then scheduling flexibility is improved, but feedback overhead increases
Solution Approach 1:
The patent merges NC-JT CSI reporting with existing single-TRP CSI reporting mechanisms. The UE can report CSI that is applicable to both NC-JT and single-TRP transmissions, allowing the network to use the same feedback for different transmission modes and reducing overall feedback overhead while maintaining scheduling flexibility.
Solution Approach 2:
The patent enables dynamic CSI reporting where the UE can adapt its feedback based on the configured transmission mode. The CSI report can be dynamically adjusted to provide NC-JT specific information when needed, while falling back to conventional single-TRP CSI when applicable, optimizing the balance between flexibility and overhead.
Data Source
AI summary
Systems and methods for CSI feedback are provided. In some embodiments, a method performed by a UE for CSI feedback for Non-Coherent Joint Transmission (NC-JT) Physical Downlink Shared Channel (PDSCH) transmission from multiple Transmission/Reception Points (TRPs) includes: receiving a CSI reporting setting comprising: a set of NZP CSI-RS resources for channel measurement including a first and second NZP CSI-RS resource for channel measurement; and a set of CSI-IM resources including a first and second CSI-IM resource for interference measurement; measuring interferences based on the CSI-IM resources, where the interferences are considered different instances of a same interference if a same set of receive antennas are used, and the interferences are considered different interferences if different sets of receive antennas are used; and computing and reporting CSI feedback comprising: a NC-JT CSI and a first single TRP CSI; or a NC-JT CSI; or a CRI and a second single TRP CSI.