HARQ Feedback Postponement in TDD SPS Downlink Scheduling
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Solution Overview
Problem
The 5G NR system faces performance loss due to conflicts between Semi-Persistent Scheduling PDSCH and TDD configuration, leading to discarded HARQ feedback in non-uplink slots, which disrupts communication efficiency.
Innovation Solution
A method to enhance HARQ transmission by determining conditions for postponing HARQ feedback, selecting alternative uplink channels like PUCCH or PUSCH, and implementing a feedback group transmission operation to ensure timely and efficient HARQ feedback delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If HARQ feedback is transmitted according to fixed k1 timing configuration, then the feedback timing is simple and predictable, but the feedback may be discarded when it falls into non-uplink slots in TDD mode, causing performance loss
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed k1 timing configuration to a dynamic feedback timing mechanism. The UE determines feedback timing based on the actual TDD uplink/downlink slot configuration, selecting the nearest upcoming uplink slot for feedback transmission. This dynamic adjustment ensures feedback is always transmitted in valid uplink slots, resolving the contradiction between simple fixed timing and reliable feedback delivery in TDD mode.
Solution Approach 2:
The patent changes the feedback timing parameter from a fixed k1 value to a dynamically determined timing based on TDD configuration. Instead of using a predetermined k1, the system calculates the feedback timing by identifying the nearest uplink slot after the downlink PDSCH reception, effectively changing the timing parameter adaptively to match the TDD frame structure, thereby preventing feedback discarding.
2Ease of manufacture
If HARQ feedback is discarded when falling into non-uplink slots, then the current 3GPP protocol is compliant and simple to implement, but communication efficiency and performance deteriorate
Solution Approach 1:
The patent converts the harmful effect of TDD non-uplink slot conflicts into a beneficial mechanism. Instead of simply discarding feedback when it falls into non-uplink slots, the system uses the TDD configuration information to proactively determine the correct feedback timing. The harmful constraint (must discard in non-uplink slots) is transformed into a benefit by using the TDD slot structure to guide the feedback timing selection, ensuring feedback is always sent in valid uplink slots, thereby improving communication efficiency while maintaining protocol compliance.
3Device complexity
If k1 value is configured only in the activate DCI format for SPS PDSCH, then the configuration is simplified and follows semi-persistent scheduling characteristics, but all SPS PDSCH transmissions use the same k1 value which may not be optimal for different downlink slots
Solution Approach 1:
The patent applies segmentation by dividing the feedback timing determination into different segments based on the actual downlink slot position and TDD configuration. Instead of using a single unified k1 value for all SPS PDSCH transmissions, the system segments the feedback timing based on which specific downlink slot the PDSCH was transmitted in and determines the appropriate feedback timing for each segment individually, optimizing feedback efficiency for each case while maintaining overall system simplicity.
Data Source
AI summary
A hybrid automatic repeat request (HARQ) transmission enhancement method includes receiving a downlink transmission sent by a base station, when an abnormal process is needed in sending of a HARQ feedback signal for the downlink transmission, determining whether the HARQ feedback signal satisfies a condition for postponing feedback, and if yes, selecting a physical uplink shared channel (PUSCH) after an originally scheduled sending time unit of the HARQ feedback signal to transmit at least part of the HARQ feedback signal.