DRX HARQ RTT Timing for NTN Retransmission Scheduling
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Solution Overview
Problem
In non-terrestrial networks (NTN), the existing configuration method of drx-HARQ-RTT-TimerDL(UL) fails to achieve power saving for terminal devices due to significant differences in round trip times (RTTs) between terrestrial and NTN cells, leading to incorrect timing for monitoring the physical downlink control channel (PDCCH) and missing retransmission scheduling.
Innovation Solution
Configure the drx-HARQ-RTT-TimerDL(UL) based on the RTT of the serving cell associated with the data transmission, allowing for a suitable slot offset or duration adjustment to ensure proper timing for PDCCH monitoring and power saving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the existing configuration method of drx-HARQ-RTT-TimerDL(UL) is used in NTN with carrier aggregation, then the terminal device can operate in carrier aggregation mode, but the terminal device cannot achieve power saving and may miss retransmission scheduling due to significant RTT differences between TN and NTN cells
Solution Approach 1:
The patent applies local quality by configuring different drx-HARQ-RTT-Timer values for different serving cells based on their specific RTT characteristics. Terrestrial cells use one timer configuration while NTN cells use another configuration adapted to their longer RTT, allowing each cell to operate with locally optimized parameters rather than a uniform global setting.
Solution Approach 2:
The patent changes the timer parameter values according to the cell type. Specifically, it configures drx-HARQ-RTT-TimerDL(UL) with different duration values for TN and NTN cells, adjusting the parameter to match the propagation delay characteristics of each network type, thereby resolving the power saving issue while maintaining carrier aggregation functionality.
2Adaptability or versatility
If the existing configuration method of drx-HARQ-RTT-TimerDL(UL) is used in NTN with cross-carrier scheduling, then the terminal device can perform cross-carrier scheduling, but the terminal device starts drx-Retransmission-TimerDL(UL) at wrong time and misses retransmission scheduling
Solution Approach 1:
The patent applies local quality by configuring cell-specific drx-HARQ-RTT-Timer values that account for the RTT characteristics of the serving cell where the PDSCH is transmitted. This ensures that the drx-Retransmission-TimerDL(UL) is started at the correct time for each cell type, preventing missed retransmission scheduling while maintaining cross-carrier scheduling functionality.
3Reliability
If the terminal device monitors PDCCH continuously to avoid missing retransmission scheduling, then the terminal device can reliably receive retransmission scheduling, but the terminal device cannot achieve power saving
Solution Approach 1:
The patent implements periodic action through DRX (Discontinuous Reception) operation, where the terminal device alternates between active monitoring periods and sleep periods. By configuring appropriate drx-HARQ-RTT-TimerDL(UL) values, the terminal device monitors PDCCH only during necessary periods to catch retransmission scheduling, then enters sleep mode to save power, achieving both reliability and energy efficiency.
Data Source
AI summary
A DRX method, a terminal device and a network device are provided. The method includes: a first discontinuous reception hybrid automatic repeat request round trip time timer (drx-HARQ-RTT-Timer) is configured based on a round trip time (RTT) corresponding to a serving cell associated with a data transmission.