PUSCH Feedback Timing for Low-Latency HARQ-ACK in NR-U
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Solution Overview
Problem
Existing NR-U technologies do not effectively address how to transmit downlink feedback information (DFI) for high-priority PUSCH in unlicensed frequency bands, which is crucial for low-latency services like URLLC, leading to suboptimal HARQ-ACK feedback and increased data transmission latency.
Innovation Solution
The network device transmits DFI after the end symbol of the high-priority PUSCH, ensuring timely HARQ-ACK feedback by configuring a suitable time interval or using a timer, allowing for fast retransmission of incorrect HARQ-ACK information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If downlink feedback information is transmitted immediately after PUSCH, then feedback latency is reduced, but processing reliability deteriorates due to insufficient processing time
Solution Approach 1:
The patent applies dynamics by making the time interval between PUSCH and DFI configurable and adaptable. The network device dynamically adjusts the time offset based on processing capabilities, subcarrier spacing, and service requirements. This allows the system to optimize between fast feedback (small offset) and reliable processing (larger offset) depending on current conditions, resolving the contradiction between latency and reliability.
Solution Approach 2:
The patent changes the parameter of time offset between PUSCH and DFI from a fixed value to a configurable parameter. By adjusting this time offset parameter based on processing capabilities and service types, the system can achieve both low latency (smaller offset) and high reliability (sufficient processing time) in different scenarios, thus resolving the technical contradiction.
2Device complexity
If a fixed time interval is used between PUSCH and DFI, then system complexity is reduced, but adaptability to different subcarrier spacings deteriorates
Solution Approach 1:
The patent introduces configurable time offset parameters that can be adjusted according to subcarrier spacing and processing capabilities. Instead of a single fixed interval, the system uses parameter sets that adapt to different numerical scales of subcarrier spacing, enabling the system to maintain low complexity while achieving high adaptability across different 5G NR scenarios.
Data Source
AI summary
A communication apparatus, including: a transmitter, which in operation, transmits a physical uplink shared channel (PUSCH); a receiver, which in operation, receives downlink feedback information for the PUSCH, where a starting symbol of the downlink feedback information is after an end symbol of the PUSCH by a number of symbols, and the number of symbols is determined from a value set which is different according to a subcarrier spacing.