Discontinuous Reception Timer Management for NTN HARQ Continuity
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Solution Overview
Problem
In Non Terrestrial Networks (NTN), the long signal transmission time and increased propagation delay lead to the disabling of the Hybrid Automatic Repeat reQuest (HARQ) function, resulting in challenges for ensuring data transmission continuity without increasing the number of HARQ processes.
Innovation Solution
A discontinuous reception method is implemented, where a terminal device runs a DRX uplink or downlink retransmission timer corresponding to an HARQ process, even when the HARQ function is disabled. This is done after receiving a PDCCH indicating scheduling of transmission or after sending a PUSCH or receiving a PDSCH, ensuring continuous data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the HARQ function is disabled due to long propagation delay in NTN, then the system can operate in NTN environment, but data transmission continuity cannot be ensured without increasing the number of HARQ processes
Solution Approach 1:
The patent segments the HARQ process into multiple independent HARQ processes (first HARQ process and second HARQ process). Each process has its own timer and state machine, allowing parallel operation to handle the long propagation delay in NTN while ensuring transmission continuity without requiring a single complex HARQ process with increased parameters
Solution Approach 2:
The patent implements preliminary actions by starting the DRX uplink retransmission timer or DRX downlink retransmission timer before the actual retransmission occurs. This allows the system to proactively prepare for potential retransmissions in NTN environment, ensuring that resources are allocated and timing is synchronized before the long propagation delay causes transmission issues
2Reliability
If the number of HARQ processes is increased to ensure transmission continuity in NTN, then data transmission continuity can be maintained, but system complexity increases
Solution Approach 1:
The patent divides the HARQ functionality into separate, independently managed processes with distinct timers and state machines. This segmentation allows each process to be managed separately, reducing the complexity of tracking and managing a large number of HARQ processes while maintaining transmission continuity through parallel operation
Solution Approach 2:
Each HARQ process is equipped with its own DRX uplink retransmission timer or DRX downlink retransmission timer that operates autonomously. The timers self-manage the retransmission timing without requiring centralized control, reducing the overall system complexity while ensuring reliable retransmission in NTN environment
Data Source
AI summary
Disclosed is a discontinuous reception method, comprising: when a hybrid automatic repeat request (HARQ) function of an uplink HARQ process used for the transmission of uplink data is in a disabled state, after receiving an instruction to schedule a physical downlink control channel (PDCCH) for the transmission of the uplink data, and/or after sending a physical uplink shared channel (PUSCH) that carries the uplink data, a terminal device operating a discontinuous reception uplink retransmission timer corresponding to the uplink HARQ process. Further disclosed are another discontinuous reception method, a terminal device and a storage medium.