Unified TCI Cross-Carrier Scheduling for Default Beam Selection
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Solution Overview
Problem
Wireless communications systems face challenges in determining a default beam for downlink communications under cross-carrier scheduling in unified transmission configuration indicator (TCI) frameworks, leading to transmission failures, increased latency, and inefficient resource use when scheduling DCI is received within a threshold time duration.
Innovation Solution
User equipment (UE) selects a default TCI state based on matching physical cell identifiers (PCIs) or the lowest index value of activated TCI states if the PCIs do not match, ensuring timely data transmission and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier scheduling is implemented in unified TCI frameworks, then resource allocation flexibility is improved, but transmission reliability deteriorates due to difficulty in determining default beam
Solution Approach 1:
The patent applies preliminary action by pre-configuring TCI states and their associated PCIs before cross-carrier scheduling occurs. When scheduling DCI is received, the UE can immediately determine the default beam by checking whether the scheduled cell's PCI matches the TCI state's PCI, without needing to perform complex real-time beam determination. This advance preparation resolves the contradiction by ensuring reliable transmission while maintaining scheduling flexibility.
2Measurement precision
If default beam determination is delayed beyond threshold time duration, then processing accuracy is improved, but transmission latency increases
Solution Approach 1:
The patent pre-establishes the relationship between TCI states and PCIs before scheduling occurs. When scheduling DCI is received within the threshold time duration, the UE can immediately determine the default beam by comparing the scheduled cell's PCI with the pre-configured TCI state PCIs, eliminating the need for delayed processing while maintaining accuracy. This resolves the contradiction between processing accuracy and transmission latency.
3Reliability
If complex beam determination procedures are used, then transmission reliability is improved, but processing time increases
Solution Approach 1:
The patent extracts the essential identification element (PCI) from the complex beam determination process. Instead of performing complex real-time beam analysis, the UE only needs to compare PCIs to determine the default beam. This simplification maintains transmission reliability by ensuring correct beam selection while dramatically reducing processing time, thus resolving the contradiction between reliability and processing time.
4Speed
If PCI matching is not checked, then processing speed is improved, but beam selection accuracy deteriorates
Solution Approach 1:
The patent enables the system to self-determine the default beam through automatic PCI matching. The UE autonomously compares the scheduled cell's PCI with the TCI state's PCI and selects the appropriate beam without external intervention. This self-service mechanism maintains high processing speed while ensuring accurate beam selection, resolving the contradiction between speed and accuracy.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive control signaling on a first component carrier that indicates a first transmission configuration indicator (TCI) state and a grant of resources for receiving a data transmission or an aperiodic channel state information (A-CSI) transmission on a second component carrier that is different from the first component carrier. The UE may determine whether a first physical cell identifier (PCI) associated with the first TCI state and a second PCI associated with a serving cell of the second component carrier are the same. The UE may select the first TCI state based on the first and second PCI being the same or the first TCI corresponding to a low index value. The UE may receive, via the first TCI state, the data transmission or the A-CSI via the second component carrier according to the grant of resources.