Terminal QCL Parameter Determination for Uplink Spatial Relation
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Solution Overview
Problem
In future radio communication systems, such as NR, the spatial relation for uplink transmission is not clearly determined when spatial relation information is not provided, leading to potential deterioration in throughput and communication quality.
Innovation Solution
A terminal determines a quasi-co-located (QCL) parameter for downlink transmission when spatial relation information and path-loss reference signal information for uplink transmission are not provided, using default spatial relation and path-loss reference signal enabling information, and transmits uplink signals based on this QCL parameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If spatial relation information is not provided for uplink transmission, then the system complexity is reduced, but the throughput and communication quality deteriorate due to improper spatial relation determination
Solution Approach 1:
The base station pre-configures multiple TCI states mapped to TCI code points before uplink transmission. When spatial relation information is not provided, the terminal can autonomously select an appropriate TCI state based on the code point, eliminating the need for real-time spatial relation signaling while maintaining proper beam alignment for high throughput
Solution Approach 2:
The terminal autonomously determines the spatial relation by selecting a TCI state corresponding to a default TCI code point when spatial relation information is not provided. This self-service mechanism allows the terminal to independently resolve the spatial relation without additional base station intervention, maintaining communication quality while reducing system complexity
2Loss of information
If spatial relation information is not provided for uplink transmission, then the signaling overhead is reduced, but the communication quality deteriorates due to ambiguous spatial relation
Solution Approach 1:
The TCI states configured for downlink are made universally applicable to uplink transmission by mapping them to TCI code points. This multi-functionality allows the same TCI states to serve both downlink and uplink spatial relation determination, reducing signaling overhead while maintaining communication quality through consistent beam management
Solution Approach 2:
The terminal copies the downlink TCI state configuration to determine uplink spatial relation. By reusing the downlink TCI states and mapping them to uplink TCI code points, the system avoids redundant signaling while ensuring that uplink transmission uses appropriate spatial parameters derived from downlink measurements
3Adaptability or versatility
If multiple TCI states are mapped to TCI code points, then the adaptability to multi-TRP scenarios is improved, but the device complexity increases
Solution Approach 1:
Multiple TCI states are pre-mapped to TCI code points in advance, enabling the terminal to support multiple TRPs without real-time configuration complexity. The terminal simply selects the appropriate TCI state based on the code point indication, achieving multi-TRP adaptability while keeping device complexity manageable through pre-configured mappings
Data Source
AI summary
A terminal according to one aspect of the present disclosure includes: a control section that determines a quasi-co-located (QCL) parameter for downlink, when spatial relation information and path-loss reference signal information for uplink transmission are not provided and default spatial relation and path-loss reference signal enabling information for the uplink transmission is provided, in a case where a plurality of different TCI states mapped to a transmission configuration indication (TCI) code point are not provided; and a transmitting section that transmits the uplink transmission by using the QCL parameter. According to one aspect of the present disclosure, a spatial relation can be appropriately determined.