Adaptive HARQ Feedback Management for Ultra Low Latency Wireless Systems
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Solution Overview
Problem
In wireless communication systems, particularly in ultra low latency (ULL) environments, the challenge of providing timely hybrid automatic repeat request (HARQ) feedback is exacerbated by the reduction of communication time slots to single symbol durations, making conventional HARQ feedback operations inefficient.
Innovation Solution
The receiving device modifies HARQ feedback operations by determining to turn off HARQ feedback or simplify it by excluding negative acknowledgement (NAK) or acknowledgement (ACK) reporting, based on evaluated conditions such as signaling, channel, or traffic conditions, which influences channel quality indicator (CQI) reporting and modulation and coding scheme (MCS) usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If communication time slots are reduced to single symbol duration in ULL environments, then latency is reduced, but timely reporting of HARQ feedback becomes challenging
Solution Approach 1:
The patent segments HARQ feedback reporting into multiple opportunities across different time slots when single symbol duration is insufficient. Instead of requiring all feedback in one compressed time slot, the system divides feedback reporting into multiple manageable segments that can be transmitted across available uplink resources, making the operation feasible within ULL constraints.
Solution Approach 2:
The patent introduces additional time dimension for HARQ feedback reporting by utilizing multiple time slots and subframes. When the time slot duration is reduced to single symbol, the system compensates by extending the feedback reporting across multiple time dimensions (different subframes, different uplink slots), effectively trading time compression for temporal distribution.
2Device complexity
If HARQ feedback operations are simplified by excluding NAK or ACK reporting, then system complexity is reduced, but data transmission reliability may be affected
Solution Approach 1:
The patent implements dynamic HARQ feedback operations where the receiving device can adaptively turn off HARQ feedback or simplify it by excluding NAK or ACK reporting based on evaluated conditions. This dynamic adjustment allows the system to reduce complexity when conditions permit while maintaining reliability when needed, creating a flexible trade-off mechanism.
Solution Approach 2:
The patent changes the operational parameters of HARQ feedback by allowing the receiving device to modify feedback behavior (turn off completely, exclude NAK, exclude ACK) based on channel conditions, traffic conditions, and signaling. This parameter change approach enables the system to adapt feedback complexity to match current system state, reducing overhead when possible while preserving reliability when necessary.
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AI summary
Methods for managing hybrid automatic repeat request (HARQ) feedback are disclosed, where HARQ feedback operations by a receiving device may be modified. A receiving device may receive a data transmission. The receiving device may evaluate a condition for determining how to provide HARQ feedback in response to the data transmission. The receiving device may modify a HARQ feedback operation based at least in part on the condition. Modification of HARQ feedback operations may include turning off HARQ feedback, excluding negative acknowledgment (NAK) reporting, or excluding acknowledgement (ACK) reporting.