TCI Mode Switching for Beam Selection and Power Control
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently switching between joint and separate TCI states for uplink and downlink transmissions, particularly in scenarios where power control configurations are not defined, leading to uncertainty in beam selection and potential issues like maximum permissible exposure (MPE) or beam failure.
Innovation Solution
User equipment (UE) autonomously switches between joint and separate TCI modes based on trigger events, applies a rule to determine power control configurations, and communicates using identified TCI states, with the base station signaling the mode change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the system uses joint TCI state for both uplink and downlink, then signaling overhead is reduced, but beam selection flexibility and reliability deteriorate when power control configurations are not defined
Solution Approach 1:
The patent segments the TCI state configuration into separate uplink TCI states and downlink TCI states. When power control configurations are not defined for a joint TCI state, the system automatically switches to separate TCI states for uplink and downlink, allowing independent beam selection for each direction. This segmentation resolves the contradiction by maintaining low signaling overhead through joint states when applicable, while ensuring reliability through separate states when power control parameters are unavailable.
Solution Approach 2:
The system dynamically switches between joint TCI mode and separate TCI mode based on the availability of power control configurations. When power control parameters are defined for joint TCI states, the system uses the joint mode to reduce signaling overhead. When these parameters are not defined, it transitions to separate TCI modes to ensure reliable beam selection. This dynamic adaptation resolves the contradiction between signaling efficiency and beam selection reliability.
2Loss of time
If the system switches between TCI modes autonomously, then response time and latency are reduced, but coordination complexity with the base station increases
Solution Approach 1:
The system performs preliminary configuration by pre-defining multiple TCI states with different power control parameter combinations before actual communication. When switching is needed, the UE can immediately activate a pre-configured TCI state without extensive real-time coordination with the base station. This preliminary preparation reduces switching latency while maintaining manageable coordination complexity through predefined state configurations.
Solution Approach 2:
The UE autonomously determines when to switch between joint and separate TCI modes based on the availability of power control configurations, without requiring explicit base station commands for each switch. The UE self-manages the mode selection and TCI state activation, reducing switching latency. The base station is simply informed of the UE's capability to support separate TCI states, significantly reducing coordination complexity while enabling fast autonomous switching.
3Reliability
If separate TCI states are used for uplink and downlink, then beam selection flexibility and reliability are improved, but signaling overhead increases
Solution Approach 1:
The system applies different TCI state configurations locally based on specific conditions. When power control configurations are available for joint TCI states, the system uses joint states to minimize signaling overhead. When these configurations are not available, it locally switches to separate TCI states for uplink and downlink to ensure reliable beam selection. This local adaptation based on power control parameter availability resolves the contradiction by using separate states only where necessary.
4Reliability
If the UE reports trigger events to the base station, then communication reliability is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts and reports only the essential trigger events (such as beam failure detection, MPE threshold exceedance) to the base station, rather than reporting all possible TCI state parameters or continuous status information. This selective extraction of critical trigger events maintains communication reliability by informing the base station of important conditions while minimizing uplink signaling overhead by reporting only what is necessary for mode switching decisions.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may identify a transmission configuration indicator (TCI) state to use for communications with a network entity after switching between TCI modes (e.g., a joint TCI state mode and a separate TCI states mode for uplink transmission and downlink reception). A UE may autonomously switch between the TCI modes based on a trigger event, and may send an indication to a network entity of the trigger event prior to communicating. A UE may identify a TCI configuration with unconfigured power control parameters. The UE may determine a common power control configuration for communicating with a network entity based on applying a rule to the TCI configuration to determine the power control parameters.