UE TCI State Selection for Small Scheduling Offsets
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing beam indications for downlink transmissions, particularly when the scheduling offset between the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH) is small, leading to difficulties in determining the appropriate Transmission Configuration Indicator (TCI) state for User Equipment (UE) to use.
Innovation Solution
The system employs a method where the UE receives multiple TCI states and determines the appropriate third TCI state based on the association of reference signals with the serving cell, allowing it to buffer and receive scheduled DL receptions effectively by using the correct TCI state when the scheduling offset is smaller than a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the scheduling offset between PDCCH and PDSCH is small, then the system can achieve faster scheduling response, but the UE cannot determine the appropriate TCI state for downlink reception
Solution Approach 1:
The network pre-configures multiple TCI states for the UE before actual scheduling occurs. When scheduling with small offset is needed, the UE can immediately select from pre-configured TCI states without waiting for additional signaling, enabling fast scheduling while ensuring reliable beam indication
Solution Approach 2:
The system dynamically selects which TCI state to apply based on the scheduling offset value. When the offset is smaller than a threshold, the UE uses a default TCI state from pre-configuration; when the offset is larger, the UE can use newly indicated TCI states. This dynamic behavior resolves the contradiction by adapting the TCI state selection mechanism to the timing conditions
2Adaptability or versatility
If multiple TCI states are configured for different cells, then the system can support multi-cell operations, but the UE cannot determine which TCI state to use when scheduling offset is small
Solution Approach 1:
The patent applies different TCI state selection rules based on local conditions - specifically, whether the scheduling offset is smaller or larger than a threshold. When offset is small, the UE applies a default TCI state from pre-configuration; when offset is large, the UE uses newly indicated TCI states. This localized adaptation simplifies the selection process while maintaining multi-cell support
Solution Approach 2:
The TCI state configuration is segmented into different sets for different cells and different timing conditions. The network configures separate TCI state pools for different serving cells, and the UE segments its selection logic based on the scheduling offset threshold, choosing from appropriate segments based on current conditions
Data Source
AI summary
In an example, a User Equipment (UE) receives a first Physical Downlink Control Channel (PDCCH) indicating a first Transmission Configuration Indicator (TCI) state and a second TCI state. The first TCI state and/or the second TCI state are configured to be applied for one or more receptions. The UE receives a second PDCCH. When a scheduling offset between the second PDCCH and a scheduled DL reception is smaller than a threshold, the UE determines a third TCI state to use for the scheduled DL reception based on whether or not a first reference signal (RS) associated with the first TCI state is associated with a serving cell of the UE and/or whether or not a second RS associated with the second TCI state is associated with the serving cell. The UE receives and/or buffers the scheduled DL reception based on one or more TCI states including the third TCI state.