Selective MAC CE Feedback on HARQ-Disabled NTN Links
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Solution Overview
Problem
Disabling hybrid automatic repeat request (HARQ) feedback in non-terrestrial networks (NTN) such as NB-IoT and eMTC can reduce user equipment power consumption and latency but degrades layer 1 reliability of downlink transmission, particularly affecting important physical channels like PDSCH and MAC CE activation.
Innovation Solution
Implementing feedback transmission for downlink medium access control control elements (MAC CEs) on HARQ processes with disabled HARQ feedback by using specific formats indicated by the network device, allowing acknowledgement (ACK) or non-acknowledgement (NACK) feedback, even when HARQ feedback is disabled, through formats like NPDSCH and NPUSCH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If HARQ feedback is disabled, then user equipment power consumption and latency are reduced, but layer 1 reliability of downlink transmission degrades
Solution Approach 1:
The patent segments the HARQ feedback mechanism by separating PDSCH feedback (disabled) from MAC CE feedback (enabled). This allows selective feedback for critical control elements while maintaining overall low-power operation, resolving the contradiction between energy saving and reliability for essential transmissions.
Solution Approach 2:
The patent applies different feedback configurations to different transmission types: PDSCH uses disabled feedback for energy saving, while MAC CE uses enabled feedback for reliability. This local differentiation allows the system to optimize each transmission type according to its specific requirements, balancing power consumption and reliability.
2Productivity
If HARQ feedback is disabled, then uplink throughput is improved, but system operation integrity is impacted
Solution Approach 1:
The patent segments feedback requirements by transmission type, enabling feedback for MAC CE (which affects system operation) while maintaining disabled feedback for PDSCH. This segmentation preserves uplink throughput benefits while ensuring system operation integrity through selective feedback for critical control elements.
Solution Approach 2:
The patent reintroduces feedback specifically for MAC CE transmissions on HARQ processes with disabled feedback. This targeted feedback mechanism ensures system operation integrity is maintained without compromising the overall uplink throughput benefits achieved by disabling feedback for most PDSCH transmissions.
3Loss of time
If HARQ feedback is disabled, then latency is reduced, but downlink transmission reliability degrades
Solution Approach 1:
The patent segments the feedback disablement approach, maintaining low latency by disabling feedback for PDSCH while enabling feedback for MAC CE. This segmentation allows the system to achieve reduced latency for data transmissions while preserving reliability for control elements that require acknowledgment.
Solution Approach 2:
The patent applies different latency-reliability trade-offs locally: PDSCH transmissions benefit from low latency with disabled feedback, while MAC CE transmissions use enabled feedback to ensure reliability. This local optimization allows the system to minimize overall latency while maintaining reliability where it matters most.
Data Source
AI summary
Disclosed are devices, methods, apparatuses, and computer readable media for feedback transmission. An example terminal device may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the terminal device at least to perform: receiving from a network device, a downlink medium access control control element on a hybrid automatic repeat request process configured or indicated with hybrid automatic repeat request feedback disabled; and transmitting to the network device, a feedback for the downlink medium access control control element.