PUCCH Time Resource Indicator for HARQ-ACK Feedback in NR-U
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Solution Overview
Problem
In NR-U systems, the base station cannot predict the time of the next DL COT, making it impossible to explicitly indicate the time difference between PDSCH and HARQ-ACK feedback, which results in the UE being unable to accurately learn the time slot for feeding back HARQ-ACK.
Innovation Solution
A method is provided to determine whether the PDSCH-to-HARQ-timing-indicator field indicates the time difference between PDSCH and PUCCH for HARQ-ACK feedback, generate indication information based on this determination, and indicate this information to the UE through downlink control information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the base station uses the third transmission method (instructing UE to access channel by itself) in NR-U system, then the UE can transmit HARQ-ACK information after successfully accessing the channel, but the base station cannot predict the time of the next DL COT and cannot explicitly indicate the time difference between PDSCH and HARQ-ACK feedback
Solution Approach 1:
The patent introduces a new Downlink Control Information (DCI) field called 'PUCCH time resource indicator' as an intermediary to convey timing information. This field indirectly indicates the PUCCH transmission time by referencing pre-configured time resources, thereby mediating between the base station's inability to predict next DL COT and the UE's need to know when to transmit HARQ-ACK
Solution Approach 2:
The patent employs preliminary action by pre-configuring multiple PUCCH time resources through higher-layer signaling before actual HARQ-ACK transmission. These pre-configured time resources allow the base station to indicate timing information in advance through the DCI field, enabling the UE to prepare for timely feedback transmission without requiring the base station to predict future DL COT times
2Measurement precision
If the base station cannot explicitly indicate the time difference between PDSCH and HARQ-ACK feedback, then the UE cannot accurately learn the time slot for feeding back HARQ-ACK, but adding explicit indication increases downlink control information overhead
Solution Approach 1:
The patent applies partial action by using a compact DCI field that provides just enough timing information needed for PUCCH transmission. Instead of providing complete time difference indication, the field selectively indicates from pre-configured options, achieving necessary precision while minimizing control overhead
Solution Approach 2:
The patent inverts the traditional approach by having the UE determine PUCCH timing based on pre-configured resources rather than having the base station calculate and indicate the exact time difference. This inversion reduces the information burden on DCI while maintaining accurate timing indication
Data Source
AI summary
A method for indicating a time difference between a PUCCH and a PDSCH, a base station, and a readable medium. The method for indicating a time difference between a PUCCH and a PDSCH comprises: determining whether a PDSCH-to-HARQ-timing-indicator field indicates a time difference between a PDSCH and a PUCCH which is used for feeding back HARQ-ACK; generating indication information according to the indication result; and indicating the indication information to the UE by means of downlink control information. By applying the solution, a UE is able to accurately acquire a time slot for feeding back HARQ-ACK while a time difference between a PDSCH and a PUCCH which is used for feeding back the HARQ-ACK is indicated by a PDSCH-to-HARQ-timing-indicator field.