UE PDSCH Reception via Subset QCL Assumptions
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently receiving and scheduling multiple physical downlink shared channels (PDSCHs) due to limitations in quasi co-location (QCL) assumptions, which can impact performance, especially in higher frequency bands like FR2, where scheduling offsets may not allow timely beam indication, leading to suboptimal reception.
Innovation Solution
Implementing a method where user equipment (UE) receives downlink control information (DCI) that schedules multiple PDSCHs based on QCL assumptions for different subsets, allowing separate or single beam usage depending on scheduling offsets, thereby improving performance by applying appropriate QCL assumptions for various subsets of PDSCHs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single QCL assumption is applied to all scheduled PDSCHs, then device complexity is reduced, but reception reliability deteriorates when scheduling offsets vary
Solution Approach 1:
The patent segments the scheduled PDSCHs into different subsets based on their scheduling offsets relative to the QCL time duration. PDSCHs with scheduling offsets greater than or equal to the QCL time duration form one subset, while those with smaller offsets form another subset. This segmentation allows different QCL assumptions to be applied to different subsets, resolving the contradiction by maintaining reliability through differentiated handling while managing complexity through systematic categorization.
Solution Approach 2:
The patent applies different QCL assumptions to different subsets of PDSCHs based on their specific scheduling characteristics. Instead of using a uniform QCL assumption for all PDSCHs, the system tailors the QCL assumption selection to the local conditions of each subset, thereby optimizing reception reliability for each case while maintaining overall system manageability.
2Reliability
If separate beam indications are provided for each PDSCH, then reception reliability is improved, but control signaling overhead increases
Solution Approach 1:
The patent merges the beam indication for multiple PDSCHs into a single DCI message by providing a single TCI codepoint that corresponds to multiple TCI states. Each TCI state indicates a different QCL assumption, and the UE can determine the appropriate TCI state based on the scheduling offset of each PDSCH. This merging approach reduces control signaling overhead compared to providing separate beam indications for each PDSCH, while still maintaining reception reliability through differentiated QCL assumption application.
Solution Approach 2:
The single TCI codepoint in the DCI serves multiple functions by encoding references to multiple TCI states. This universal indicator allows the system to convey beam indication information for multiple PDSCHs with different scheduling offsets through a single signaling element, thereby reducing overhead while maintaining the ability to provide appropriate beam indications for each PDSCH subset.
3Reliability
If beam indication timing is extended to accommodate QCL processing, then reception reliability is improved, but scheduling flexibility is reduced
Solution Approach 1:
The patent applies QCL assumptions preliminarily by having the UE determine the appropriate TCI state from the received TCI codepoint before actually receiving each PDSCH. This preliminary determination allows the UE to prepare the correct beam configuration in advance, ensuring reliable reception. The system accommodates the QCL processing time requirement by using the scheduling offset information to select the appropriate TCI state beforehand, thus maintaining both reliability and scheduling flexibility.
Solution Approach 2:
The patent introduces dynamic selection of QCL assumptions based on the scheduling offset of each PDSCH. The UE dynamically determines which TCI state to apply by comparing the scheduling offset with the QCL time duration threshold. This dynamic approach allows the system to adapt to different scheduling scenarios while ensuring that sufficient time is allocated for QCL processing when needed, thereby maintaining both reliability and scheduling flexibility.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a downlink control information (DCI) that schedules a plurality of physical downlink shared channels (PDSCHs). The UE may receive, from the base station, the plurality of PDSCHs based at least in part on a quasi co-location (QCL) assumption applied for different subsets of the plurality of PDSCHs. Numerous other aspects are described.