RRC_INACTIVE Small Data Transmission with Adaptive RA-SDT and CG-SDT
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Solution Overview
Problem
Existing communication protocols for user equipment (UE) in RRC_INACTIVE state face challenges in managing small data transmissions efficiently, particularly in scenarios where the UE's ability to perform random access procedures or utilize configured grants is unclear, leading to inefficiencies and potential misconfigurations.
Innovation Solution
The UE manages small data transmission by receiving an SDT configuration from the RAN, determining support for RA-SDT and/or CG-SDT, and performing communication procedures based on these configurations, including random access and dynamic grants, to optimize data transmission in the RRC_INACTIVE state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions to RRC_CONNECTED state for data transmission, then reliable data communication is achieved, but latency increases and network resources are consumed
Solution Approach 1:
The patent segments the data transmission process into two parts: control plane connection (maintained in RRC_INACTIVE state) and user plane data (transmitted via SDT procedure). This allows the UE to maintain connection reliability without full state transition, resolving the contradiction between reliability and latency.
Solution Approach 2:
The network performs preliminary actions by configuring SDT parameters, random access resources, and configured grant resources before the UE needs to transmit data. The UE also preliminarily determines its capability support for RA-SDT and CG-SDT, enabling quick execution of data transmission without full state transition.
2Adaptability or versatility
If the UE performs random access procedure for SDT transmission, then data transmission capability is established, but procedure complexity increases
Solution Approach 1:
The patent implements dynamic selection between two SDT procedures (RA-SDT and CG-SDT) based on UE capability and network configuration. The UE dynamically determines which procedure to use by checking its support for random access and configured grant resources, simplifying the overall complexity through adaptive behavior.
Solution Approach 2:
The network performs preliminary configuration of random access resources and configured grant resources before the UE needs to transmit data. The UE also preliminarily determines its capability support, enabling quick execution of the selected procedure without complex real-time decisions.
3Productivity
If the UE uses configured grant resources for SDT, then transmission efficiency is improved, but timing alignment requirements increase
Solution Approach 1:
The network performs preliminary timing alignment configuration and the UE maintains timing alignment information before SDT transmission is needed. The configured grant resources are pre-configured with appropriate timing parameters, enabling efficient transmission while maintaining reliability through pre-established timing alignment.
4Adaptability or versatility
If the network configures both RA-SDT and CG-SDT resources, then transmission flexibility is improved, but configuration complexity increases
Solution Approach 1:
The network performs preliminary configuration of both RA-SDT and CG-SDT resources, along with UE capability determination, before the UE needs to transmit data. This pre-configuration enables the UE to flexibly select the appropriate procedure based on current conditions without complex real-time configuration decisions.
Data Source
AI summary
A radio access network (RAN) and a user equipment (UE) can implement a method for managing small data transmission (SDT). The method includes: (i) operating in a state of a protocol for controlling radio resources in which the UE is not connected to the RAN; (ii) receiving an SDT configuration from the RAN; and (iii) performing, based on whether the UE and the RAN node support an SDT type that relies on a random access procedure, a communication procedure with the RAN node to transmit or receive small data.