PDCCH Repetition Beam Selection for Ambiguous CORESET and TCI States
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Solution Overview
Problem
In wireless communication systems, the ambiguity in determining a default downlink or uplink beam for data channels scheduled by a physical downlink control channel (PDCCH) with repetition configurations, particularly when associated with multiple control resource sets (CORESETs) and transmission configuration indication (TCI) states, leads to uncertainty in beam selection for UEs.
Innovation Solution
UEs determine a default beam for downlink or uplink data channels based on the repetition configuration, utilizing multiple CORESETs or TCI states associated with the CORESET, by mapping TCI states to different reception or transmission occasions, or selecting a TCI state when repetitions are configured.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCCH repetition is configured with multiple CORESETs or TCI states, then reliability of control channel transmission is improved, but beam determination ambiguity increases for scheduled data channels
Solution Approach 1:
The patent applies preliminary action by pre-configuring QCL relationships between CORESETs and TCI states before PDCCH transmission. The UE is provided with configuration information that establishes predetermined quasi co-location relationships, allowing the UE to determine the default beam for scheduled data channels based on these pre-established relationships rather than attempting to resolve ambiguity at the moment of reception. This resolves the beam determination ambiguity while maintaining the reliability benefits of PDCCH repetition.
2Loss of information
If DCI message is transmitted without TCI field to reduce overhead, then signaling efficiency is improved, but beam indication capability is lost for scheduled data channels
Solution Approach 1:
The patent introduces an intermediary mechanism by using QCL relationships as a mediator between the PDCCH configuration and the scheduled data channel. Instead of directly indicating the beam in the DCI message (which would increase overhead), the system uses the pre-configured QCL relationships between CORESETs and TCI states as an indirect indication mechanism. The UE determines the default beam for the scheduled data channel by referencing the QCL relationship of the CORESET used for PDCCH reception, thus maintaining signaling efficiency while preserving beam indication capability.
3Reliability
If multiple TCI states are associated with a single CORESET for diversity, then transmission robustness is improved, but default beam selection becomes ambiguous
Solution Approach 1:
The patent applies local quality by establishing distinct QCL relationships for different TCI states within the same CORESET. Each TCI state is associated with specific reference signals and has defined QCL properties, creating localized quality characteristics for each beam option. When determining the default beam for a scheduled data channel, the UE refers to the specific QCL relationship of the used CORESET configuration, which provides precise beam selection guidance even when multiple TCI states are available, thus resolving the ambiguity while maintaining transmission robustness.
Data Source
AI summary
In a wireless network, a physical downlink control channel (PDCCH) may be transmitted in multiple repetitions, which may cause ambiguity in cases where a user equipment (UE) has to determine a default downlink or uplink beam to receive or transmit a data channel. Accordingly, in cases where a UE receives a PDCCH associated with a repetition configuration and the PDCCH does not include a beam indication, the UE may determine a default beam to receive or transmit a data channel scheduled by the PDCCH based on the repetition configuration of the PDCCH. For example, the PDCCH may be associated with multiple control resource sets (CORESETs) and/or a CORESET associated with multiple transmission configuration indication (TCI) states. Accordingly, the UE may determine the default beam based on one or more parameters associated with the multiple CORESETs and/or the multiple TCIs associated with a CORESET.