UL Grant-Free Transmission Timing Control via Offset Signaling
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Solution Overview
Problem
Future radio communication systems, such as NR, face challenges in controlling Ultra Reliable and Low Latency Communications (URLLC) by reducing latency and ensuring high reliability, particularly in determining the start timing for UL grant-free transmission without a physical layer UL grant.
Innovation Solution
A user terminal controls UL grant-free transmission by determining the start timing based on offset information included in physical layer signaling, allowing flexible instruction and appropriate scheduling of UL grant-free resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If UL grant-free transmission is implemented to reduce latency, then transmission delay is reduced, but control precision and timing determination become uncertain
Solution Approach 1:
The base station performs preliminary actions by notifying the terminal of offset information through higher layer signaling (RRC signaling) and physical layer signaling (PDCCH) before UL grant-free transmission occurs. This pre-configuration of timing offset values enables the terminal to accurately determine transmission start timing without requiring real-time grants, thus reducing latency while maintaining timing precision through advance preparation.
2Speed
If UL grant-free transmission is implemented to reduce latency, then communication speed is improved, but control complexity increases
Solution Approach 1:
The control mechanism is segmented into multiple signaling layers: higher layer signaling (RRC) provides semi-static configuration of offset information, while physical layer signaling (PDCCH) provides dynamic activation and adjustment. This segmentation allows the system to maintain fast UL grant-free transmission for speed improvement while distributing control complexity across different signaling planes, with the terminal following clear procedural steps for determining transmission timing.
3Adaptability or versatility
If offset information is provided through physical layer signaling to enable flexible timing control, then adaptability is improved, but information overhead increases
Solution Approach 1:
The offset information is merged with existing signaling structures rather than being transmitted as separate dedicated signals. The timing offset values are incorporated into RRC signaling messages and PDCCH formats that already exist in the LTE system. This merging approach provides flexible timing control adaptability while minimizing additional information overhead by reusing established signaling frameworks.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
To appropriately control UL grant-free transmission, a user terminal according to one aspect of the present invention includes: a transmission section that performs UL grant-free transmission for transmitting UL data without a UL transmission instruction from a radio base station; and a control section that controls the UL grant-free transmission based on a periodicity of a UL grant-free transmission resource notified by a higher layer signaling, and a physical layer signaling for notifying activation of the UL grant-free transmission, and the control section determines a start position of the UL grant-free transmission resource to which a given periodicity is applied based on offset information included in the physical layer signaling.