Uplink Spatial Relation Info Switch Delay Management
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Solution Overview
Problem
In New Radio (NR) wireless communications, the delay requirements and user equipment (UE) behavior during a spatial relation information change for uplink signals such as SRS, PUCCH, and PUSCH are unspecified, leading to potential missed transmissions and suboptimal resource usage due to unclear transmission configuration indicators (TCI) states.
Innovation Solution
The UE behavior and delay requirements are defined for spatial relation info changes, where the UE can transmit with the same spatial filter as the downlink reference signal (DL RS) when its TCI state is known, or perform measurements and switch to the new Tx beam after a determined delay when the TCI state is unknown, ensuring proper alignment with the new spatial relation info.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the UE transmits immediately upon receiving spatial relation information, then transmission timeliness is improved, but transmission reliability deteriorates due to potential TCI state uncertainties and beam misalignment
Solution Approach 1:
The UE performs preliminary actions by determining whether the TCI state is known before transmitting. When the TCI state is known, the UE can immediately use the spatial filter for transmission. When unknown, the UE first performs measurements and determines the appropriate beam before transmission, ensuring reliability without unnecessary delays when conditions permit.
2Manufacturing precision
If the UE performs measurements and switches to new Tx beam, then spatial alignment accuracy is improved, but transmission delay increases due to measurement and processing time
Solution Approach 1:
The patent changes the parameter of TCI state knowledge status to determine the transmission approach. When TCI state is known, immediate transmission occurs with zero measurement delay. When unknown, the UE performs measurements and waits for delay time period before switching beams, optimizing the balance between precision and delay based on the specific condition.
3Device complexity
If the UE uses same spatial filter as DL RS, then transmission complexity is reduced, but adaptability deteriorates when TCI state is unknown
Solution Approach 1:
The patent makes the transmission approach dynamic based on TCI state knowledge. The UE adaptively selects between two modes: using the same spatial filter as DL RS (simple mode) when TCI state is known, or performing measurements and switching beams (complex mode) when TCI state is unknown. This dynamic adaptation optimizes complexity while maintaining versatility.
Data Source
AI summary
Various embodiments herein provide techniques for user equipment (UE) behavior and delay requirements in case of spatial relation information change for an uplink signal, such as a sounding reference signal (SRS), a physical uplink control channel (PUCCH), and/or a physical uplink shared channel (PUSCH). In one example, the UE determines a delay time period from receipt of a message that indicates spatial relation information for uplink transmission. The delay time period includes a decoding time period and a UE processing and preparation time period. The UE transmits an uplink signal using the indicated spatial relation information after expiration of the delay time period.