HARQ Scheduling Across Channel Occupation Times in 5G Unlicensed Bands
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Solution Overview
Problem
In 5G mobile communication systems using unlicensed frequency bands, user equipment (UE) faces challenges in timely feedback of acknowledgment (ACK) or non-acknowledgment (NACK) due to limited channel occupation time, which hinders reliable data transmission and potential retransmissions.
Innovation Solution
A method and device that schedule a hybrid automatic repeat request (HARQ) by transmitting downlink data in a first channel occupation time and a trigger instruction in a second channel occupation time, including identifier information or channel detection mechanism information to enable the UE to feed back reception results across channel occupation times, allowing for flexible channel detection and improved timing for feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the UE feeds back ACK/NACK in the first channel occupation time, then the feedback timing is timely, but the channel occupation time is insufficient for the UE to complete processing and feedback
Solution Approach 1:
The patent segments the channel occupation time into two distinct periods: the first channel occupation time for downlink data transmission, and the second channel occupation time for trigger instruction transmission and ACK/NACK feedback. This segmentation allows the UE sufficient processing time while maintaining overall timing efficiency by separating the data reception and feedback transmission phases.
Solution Approach 2:
The base station transmits the trigger instruction in advance during the second channel occupation time, which includes necessary information (such as time domain resource indication) that enables the UE to prepare for and execute the ACK/NACK feedback timing accurately. This preliminary provision of control information ensures the UE can meet the feedback deadline without extending the overall channel occupation time unnecessarily.
2Reliability
If the channel occupation time is extended to allow UE feedback, then the feedback can be completed, but the channel occupation time limit is violated
Solution Approach 1:
The patent employs periodic action by utilizing a second channel occupation time that occurs after the first channel occupation time. The base station transmits the trigger instruction in this subsequent period, and the UE provides feedback within this structured periodic framework. This approach ensures feedback completion while respecting the channel occupation time limit for each individual period, as the feedback is transmitted in the second periodic opportunity rather than extending the first period.
3Loss of time
If the UE detects channel during the first channel occupation time, then the feedback timing is optimized, but the UE cannot detect channel properly due to ongoing downlink transmission
Solution Approach 1:
The patent segments the channel detection and feedback operations into the second channel occupation time, separate from the downlink data transmission in the first channel occupation time. This temporal segmentation allows the UE to perform channel detection and transmit ACK/NACK feedback during the second period when the downlink transmission has ceased, eliminating interference and enabling proper channel detection while maintaining optimized feedback timing.
Data Source
AI summary
The present disclosure provides a method and a device for scheduling a hybrid automatic repeat request. The method includes: transmitting downlink data to user equipment (UE) in a first channel occupation time; and transmitting a trigger instruction to the UE in a second channel occupation time, in which the trigger instruction is configured to instruct the UE to feed back a reception result about the downlink data in the second channel occupation time, and the trigger instruction includes at least one of identifier information of the first channel occupation time, and channel detection mechanism information of transmitting the reception result.