Inactive Small Data Transmission Thresholding in Terminal RRC State
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Solution Overview
Problem
The uncertainty in how terminal devices calculate the data volume for inactive small data transmission in RRC_INACTIVE state is not explicitly defined, leading to unclear initiation of small data transmission.
Innovation Solution
The terminal device determines a first data volume that includes the data volume of RRC messages and buffered DRBs, optionally with MAC CEs and protocol headers, and compares this volume to thresholds for channel quality and data volume to decide on initiating inactive small data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the terminal device determines data volume for inactive small data transmission without explicit calculation rules, then the device complexity is reduced, but the measurement precision of data volume determination deteriorates
Solution Approach 1:
The patent changes the parameter definition from ambiguous 'data volume to be transmitted' to a explicit sum of three components: RRC message data volume + buffered DRB data volume + MAC CE data volume. This parameter transformation resolves the contradiction by providing precise calculation rules without significantly increasing device complexity, as the terminal only needs to sum existing buffer values and message sizes.
2Measurement precision
If the terminal device includes MAC CE and protocol headers in data volume calculation, then the measurement precision of data volume determination is improved, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by having the terminal device pre-calculate and include MAC CE and protocol header sizes in the data volume determination. These overhead values are accounted for in advance during the data volume calculation phase, ensuring precise threshold comparison without requiring complex real-time computations during actual transmission decisions.
3Reliability
If the terminal device uses a clear data volume calculation method including RRC messages and buffered DRBs, then the reliability of small data transmission initiation is improved, but the loss of time for calculation increases
Solution Approach 1:
The terminal device performs self-service by autonomously calculating its own data volume using locally available information (RRC message size, DRB buffer status, MAC CE size). This self-calculated approach ensures reliable transmission initiation decisions without requiring time-consuming interactions with the network side, thus improving reliability while minimizing calculation time through local resource utilization.
Data Source
AI summary
Embodiments of the present application provide a small data transmission method and apparatus, and a terminal device. The method comprises: the terminal device determines a first data amount, which comprises a data amount of radio resource control (RRC) messages and a data amount of at least one data radio bearing (DRB) cache; and the terminal device determines, based on the first data amount, whether to initiate an inactive state small data transmission.