Dynamic Repetition Factor Adjustment for NTN Uplink Reliability
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Solution Overview
Problem
In non-terrestrial networks, the rapid and semi-predictive changes in channel conditions render existing repetition factors for uplink channels obsolete, impacting the performance of periodic channel state information reporting.
Innovation Solution
A terminal device dynamically adjusts the repetition factor based on parameters such as duration values, distance and elevation angles, and initial timings, using configurations received via RRC signaling or SIB, to ensure optimal transmission in changing channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a small repetition factor is used when the satellite is located exactly above the UE, then the periodic CSI reporting performance is sufficient, but the repetition factor becomes too small when the satellite approaches the horizon, impacting CSI reporting performance
Solution Approach 1:
The patent applies dynamics by making the repetition factor adjustable and time-varying based on satellite position. Instead of using a fixed repetition factor, the system dynamically selects from a set of repetition factors according to the satellite's elevation angle or time duration, allowing the transmission parameters to adapt to changing channel conditions as the satellite moves from overhead to horizon positions.
Solution Approach 2:
The patent changes the repetition factor parameter based on satellite position parameters (elevation angle or time duration). By configuring multiple repetition factors and selecting appropriate ones based on current satellite position, the system adjusts the transmission parameters to match the changing channel conditions, resolving the contradiction between efficiency and reliability.
2Device complexity
If a fixed repetition factor is configured for uplink channel transmission, then the configuration is simple, but the repetition factor becomes obsolete quickly due to rapid channel condition changes in NTN
Solution Approach 1:
The patent segments the repetition factor configuration into multiple discrete values organized in a set. Instead of using a single fixed repetition factor, the system divides the possible repetition factors into a collection that can be selectively applied based on channel conditions, making the configuration manageable while improving adaptability.
Solution Approach 2:
The patent performs preliminary action by pre-configuring a set of repetition factors and associated parameters (such as duration values or elevation angle ranges) before transmission begins. This allows the terminal device to quickly select the appropriate repetition factor based on current satellite position without requiring complex real-time calculations, balancing configuration simplicity with adaptability.
3Reliability
If the repetition factor is adjusted frequently to match changing channel conditions, then the uplink transmission reliability is maintained, but the signaling overhead increases
Solution Approach 1:
The patent applies self-service by enabling the terminal device to autonomously determine the appropriate repetition factor based on pre-configured parameters and current satellite position information. The network device provides the configuration once, and the terminal device independently selects and applies the correct repetition factor without requiring continuous network signaling, reducing overhead while maintaining reliability.
Solution Approach 2:
The system uses feedback mechanisms where the terminal device monitors satellite position (elevation angle or time duration) and selects repetition factors from the configured set based on this feedback. This closed-loop approach ensures reliable transmission adaptation while minimizing signaling overhead by using locally available position information rather than network-directed adjustments.
Data Source
AI summary
Disclosed are devices, methods, apparatuses, and computer readable media for dynamically adjusting repetition factor. An example terminal device may include at least one processor and at least one memory. The at least one memory may include computer program code, and the at least one memory and the computer program code may be configured to, with the at least one processor, cause the terminal device to perform: receiving, from a network device, a configuration for transmission of an uplink channel, the configuration comprising a repetition factor set and at least one parameter for determining a repetition factor from the repetition factor set; determining the repetition factor from the repetition factor set based on the at least one parameter; and performing the transmission of the uplink channel according to the determined repetition factor.