Downlink Control Channel Repetition for TCI State Selection
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Solution Overview
Problem
In wireless communications systems, user equipment (UE) may face challenges in determining which transmission configuration indicator (TCI) state to use for a random access procedure when multiple downlink control channel candidates are associated with different TCI states, leading to uncertainty in decoding performance.
Innovation Solution
The UE receives an indication that two downlink control channel candidates are linked for repetition, with one candidate associated with a first TCI state and the other with a second TCI state, and selects one of these states based on signal quality or timing for the random access procedure, using DCI to determine the appropriate TCI state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple downlink control channel candidates are associated with different TCI states, then the UE can receive control information via multiple candidates, but the UE cannot determine which TCI state to use for the random access procedure
Solution Approach 1:
The patent applies feedback by having the UE measure and report on the downlink control channel candidates, and the base station uses this feedback to select which TCI state to associate with the random access procedure. The UE provides feedback about the quality of different TCI states, and this feedback is used to make the final selection, resolving the uncertainty about which TCI state to use.
Solution Approach 2:
The patent changes the parameter of TCI state association dynamically. Instead of having a fixed association between control channel candidates and TCI states, the system allows the TCI state to be selected based on measured parameters such as signal quality, beam direction, and channel conditions. This dynamic parameter change enables the system to adapt to varying radio conditions and select the optimal TCI state for random access.
2Reliability
If the UE selects TCI state based on signal quality measurement, then the decoding performance is enhanced, but the complexity of determining the correct TCI state increases
Solution Approach 1:
The patent applies self-service by having the UE autonomously measure and evaluate the quality of different TCI states based on downlink control channel reception. The UE uses its own measurements of signal quality, reference signal received power, and channel conditions to determine which TCI state to select, without requiring complex external intervention or manual configuration. This self-service approach simplifies the overall system complexity while maintaining high decoding performance.
Solution Approach 2:
The patent replaces complex mechanical decision-making processes with automated signal quality-based selection mechanisms. Instead of requiring complex algorithms or manual intervention to determine the correct TCI state, the system uses straightforward signal quality measurements and pre-configured selection criteria. This substitution of complex decision logic with simpler, signal-driven mechanisms reduces device complexity while improving reliability.
3Adaptability or versatility
If the base station transmits control information via multiple downlink control channel candidates, then the coverage is improved, but the UE cannot determine which TCI state to use for subsequent random access
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of a TCI state indication field or implicit indication mechanism within the downlink control information. This intermediary element carries the necessary TCI state information from the base station to the UE, ensuring that the UE receives both the control information and the associated TCI state indication. This intermediary mechanism prevents information loss while maintaining the benefits of multiple control channel candidates for improved coverage.
Solution Approach 2:
The patent applies preliminary action by having the base station pre-configure and indicate the TCI state association with each downlink control channel candidate before the UE needs to perform random access. The TCI state information is provided in advance through control signaling, allowing the UE to have all necessary information ready before initiating the random access procedure. This preliminary provision of information eliminates uncertainty and prevents information loss.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive, from a network device, a downlink control channel order requesting the UE to participate in random access procedure via two or more downlink control channel candidates associated with different transmission configuration indicator (TCI) states that are linked for repetition. In some examples, downlink control information conveying the downlink control channel order may indicate which TCI state to use for the random access procedure. In some examples, the UE may select a TCI state to use for the random access procedure, for example, based on the channel quality of the downlink control channel candidates.