CORESET Beam Failure Recovery via QCL Assumption
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Solution Overview
Problem
Current specifications for next-generation mobile communication systems, such as NR, do not allow for beam failure recovery (BFR) to be applied to CORESET #0, which restricts the use of unicast PDCCH in CORESET #0, leading to reduced communication throughput.
Innovation Solution
A user terminal is equipped with a receiving section for beam failure detection and a control section that determines reference signal indices for BFR, even when no TCI state is configured for a CORESET, by using indices corresponding to a QCL assumption, allowing BFR to be performed for CORESET #0.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If BFR is not applied to CORESET #0, then the specification remains simple and clear, but communication throughput is reduced due to restricted unicast PDCCH usage
Solution Approach 1:
The patent extends the BFR mechanism, originally designed for dedicated BFD-RS, to also apply to CORESET #0 by establishing a universal reference signal identification method. The UE can now perform BFR for CORESET #0 by using QCL assumption-based RS indices, making the BFR capability universal across different PDCCH configurations and thereby enabling unicast PDCCH usage in CORESET #0 to improve throughput.
Solution Approach 2:
The patent introduces QCL assumption as an intermediary mechanism to bridge the gap between CORESET #0 configuration and BFR requirement. By using the QCL assumption associated with CORESET #0 as the basis for identifying reference signals for BFR, the system enables BFR functionality without requiring separate dedicated BFD-RS configuration, thus resolving the contradiction between specification simplicity and throughput enhancement.
2Reliability
If dedicated BFD-RS is configured for CORESET #0, then BFR can be performed accurately, but configuration complexity and signaling overhead increase
Solution Approach 1:
The patent enables CORESET #0 to serve its own beam failure detection needs by utilizing its existing QCL assumption configuration. Instead of requiring external dedicated BFD-RS configuration, the system allows CORESET #0 to self-identify reference signals for BFR through its inherent QCL assumption, thereby achieving reliable beam failure detection without increasing configuration complexity or signaling overhead.
Solution Approach 2:
The QCL assumption configured for CORESET #0 is made multi-functional by allowing it to serve both as a quasi-co-location reference for PDCCH reception and as a basis for beam failure detection. This universal usage of the QCL assumption eliminates the need for separate dedicated BFD-RS configuration while maintaining accurate BFR capability.
Data Source
AI summary
A user terminal according to one aspect of the present disclosure includes a receiving section that receives a reference signal (RS) for beam failure detection (BFD), and a control section that determines, in a case that no set of RS indices corresponding to a resource for the BFD is configured by higher layer signaling, RS indices up to a certain number to be included in the set, based on a TCI (Transmission Configuration Indication) state configured for a CORESET (COntrol REsource SET). The control section includes, for a CORESET for which no TCI state is configured, an RS index of a same value as an RS index corresponding to a QCL (Quasi-Co-Location) assumption for the CORESET, in the set. According to one aspect of the present disclosure, it is possible to appropriately identify a reference signal for BFR.