Quasi Co-Location Reset for Single Active TCI State UEs
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Solution Overview
Problem
In wireless communications, user equipment (UE) with a single active transmission configuration indication (TCI) state faces challenges in managing active receive beams, particularly during random access channel procedures, where updating the quasi co-location (QCL) assumption for control resource sets can exceed its capability, leading to complexity in identifying suitable beams for communication.
Innovation Solution
The UE implements a technique to reset the QCL assumption by deactivating the single active TCI state after a random access channel procedure and using the downlink beam selected during the procedure for all downlink shared channel and control channel monitoring, thereby avoiding the need for multiple receive beams and staying within its capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE updates the QCL assumption for control resource sets during random access channel procedure, then the downlink beam can be optimized for better communication quality, but the UE exceeds its capability of supporting single active TCI state
Solution Approach 1:
The patent applies dynamics by making the TCI state configuration changeable over time. The UE transitions from a static single active TCI state to a dynamic configuration where the QCL assumption can be updated during random access procedures. This allows the system to adapt the beam configuration based on current communication needs while managing UE capabilities through time-varying states.
Solution Approach 2:
The patent changes the QCL assumption parameter during random access channel procedures. By updating the QCL reference signal association and modifying the TCI state configuration, the system optimizes the downlink beam parameters to match the current spatial characteristics, thereby improving communication quality without requiring permanent multi-state support.
2Adaptability or versatility
If the UE is configured with multiple active TCI states, then it can support multiple receive beams for different control resource sets, but the device complexity increases
Solution Approach 1:
The patent segments the TCI state management by separating the control resource set configuration from the data channel configuration. Different TCI states can be assigned to different control resource sets, allowing the UE to handle multiple beams for control channels while maintaining a manageable configuration structure that doesn't overwhelm the device complexity.
Solution Approach 2:
The patent makes the TCI state configuration universal by allowing a single TCI state to serve multiple purposes - it can be used for both control channel monitoring and data channel reception. This multi-functionality reduces the need for separate beam configurations for different channel types, thereby reducing overall UE complexity while maintaining flexibility.
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AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) with the capability to support a single active TCI state may receive configuration signaling which configures the UE with an active transmission configuration indication (TCI) state corresponding to a first beam for a control resource set and a shared data channel. The UE may perform a random access channel procedure to select a second beam from a set of different beams. The UE may update a quasi co-location (QCL) assumption for the control resource set to correspond to the second beam and deactivate the active TCI state based on updating the QCL assumption. The UE may then monitor the control resource set, the shared data channel, or both, using the second beam. The UE may deactivate the TCI state and use the indicated downlink beam so that the UE does not exceed its capability.