DRX Timer Adaptation for NTN HARQ Feedback Delay
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Solution Overview
Problem
In non-terrestrial networks (NTN), the large communication delay due to satellite positioning affects the process of transmitting hybrid automatic repeat request (HARQ) feedback, making it unclear how to accurately start discontinuous reception (DRX) timers for uplink and downlink transmissions.
Innovation Solution
A method for starting DRX timers is introduced, where the timing is adapted based on the transmission type, specifically increasing or setting the DRX HARQ RTT timer by a predetermined duration or preset value, and starting the DRX retransmission timer accordingly, to account for the round-trip time and enable accurate and reliable DRX operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If satellite communication is used in NTN, then communication coverage is extended, but communication delay increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring different DRX timer values for different transmission types (broadcast, groupcast, unicast) before actual communication occurs. The terminal device is provided with multiple DRX timer values corresponding to different transmission types, and the appropriate timer is selected in advance based on the transmission type indication, thereby preparing the system ahead of time to handle the inherent satellite communication delay without affecting real-time performance.
2Device complexity
If DRX timer is started without considering transmission type, then DRX operation is simple, but DRX timing accuracy deteriorates
Solution Approach 1:
The patent implements dynamics by making the DRX timer configuration adaptive rather than static. Different DRX timer values are dynamically selected based on the transmission type (broadcast, groupcast, unicast) as indicated by the network device. This allows the DRX timing to be optimized for each specific transmission scenario, improving timing accuracy while maintaining relatively simple operation through automated selection based on transmission type indications.
Solution Approach 2:
The patent applies parameter changes by varying the DRX timer values according to different transmission types. The network device configures multiple DRX timer parameters (drx-HARQ-RTT-TimerUL, drx-HARQ-RTT-TimerDL, drx-RetransmissionTimerUL, drx-RetransmissionTimerDL) with different values for different transmission types, allowing the system to adjust timing parameters to match the specific requirements of each transmission scenario, thereby improving DRX timing accuracy.
3Reliability
If HARQ feedback process is used in NTN, then communication reliability is improved, but the large delay affects feedback transmission timing
Solution Approach 1:
The patent applies preliminary action by pre-configuring transmission type indications and corresponding DRX timer values for HARQ feedback processes in NTN. The network device configures the terminal with multiple DRX timer values corresponding to different transmission types before actual HARQ feedback transmission. This preparation in advance allows the system to handle the large satellite communication delay by having appropriate timer values ready, ensuring reliable HARQ feedback while accounting for the extended timing requirements.
Solution Approach 2:
The patent implements parameter changes by adjusting DRX timer values based on transmission type for HARQ feedback processes. Different DRX timer parameters are configured with different values for broadcast, groupcast, and unicast transmissions. This allows the HARQ feedback process to maintain reliability while adapting the timing parameters to the specific delay characteristics of each transmission type, particularly for satellite communications where delay varies by transmission mode.
Data Source
AI summary
A method for starting a discontinuous reception (DRX) timer is performed by a terminal, and includes: starting the DRX timer according to a transmission type of at least one of an uplink transmission or a downlink transmission.