DCI TCI Field Segmentation for Latency-Free State Switching
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing transmission configuration indicators (TCI) for downlink control information, particularly in switching between TCI states without incurring increased latency or overhead, especially in scenarios involving beam indication DCI and scheduling DCI.
Innovation Solution
The method involves receiving and transmitting DCI with TCI fields that indicate pairs of TCI states for use after a specific time, allowing for seamless switching between TCI states using traditional scheduling DCI without additional bits, thereby avoiding latency and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional scheduling DCI is used for TCI state switching, then latency and overhead are avoided, but the system lacks flexibility in indicating multiple TCI states
Solution Approach 1:
The TCI field is segmented to indicate different numbers of TCI states based on the presence of the SSB indication field. When SSB indication is present, the TCI field indicates a single TCI state; when absent, it indicates a pair of TCI states. This segmentation allows the same DCI structure to serve multiple functions without increasing overhead.
Solution Approach 2:
The interpretation of the TCI field is made dynamic based on the presence or absence of the SSB indication field. The system dynamically adapts the TCI state indication capability without requiring additional bits or changing the DCI structure, thereby avoiding latency while maintaining versatility.
2Adaptability or versatility
If additional bits are added to DCI for indicating multiple TCI states, then TCI state indication capability is improved, but overhead increases
Solution Approach 1:
The existing DCI structure is made multi-functional by using the TCI field to indicate different numbers of TCI states based on the presence of the SSB indication field. This universal approach allows the same DCI format to support both single TCI state indication and pair TCI state indication without requiring additional bits, thereby avoiding increased overhead while improving adaptability.
Solution Approach 2:
The interpretation parameter of the TCI field changes based on the presence of the SSB indication field. When SSB indication is present, the TCI field indicates one state; when absent, it indicates a pair. This parameter change approach allows the system to improve TCI state indication capability without adding overhead by dynamically changing how the existing bits are interpreted.
3Adaptability or versatility
If beam indication DCI and scheduling DCI use different TCI indication methods, then flexibility is improved, but device complexity increases
Solution Approach 1:
Instead of using different DCI structures for beam indication and scheduling, the invention inverts the approach by using a single unified DCI structure where the presence or absence of the SSB indication field determines the TCI state indication method. This inversion simplifies UE processing by providing a consistent interpretation rule while maintaining the flexibility to indicate different numbers of TCI states.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive first downlink control information (DCI) having a first transmission configuration indicator (TCI) field that indicates a pair of TCI states to be used after a first time. The UE may receive second DCI having a second TCI field that indicates a selected one or more TCI states, of the pair of TCI states, to be used for a physical downlink shared channel (PDSCH). Numerous other aspects are described.