RRC Inactive Small Data Transfer Using Suspended Radio Bearers
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Solution Overview
Problem
Existing 3GPP technologies face challenges in supporting small data transmission (SDT) in the RRC_INACTIVE state without transitioning to RRC_CONNECTED state, leading to increased power consumption and signaling overhead due to frequent connection setups and releases.
Innovation Solution
Pre-configuration of radio bearers for UE to support SDT, allowing data transmission and reception while maintaining the RRC_INACTIVE state, with network-controlled transitions to RRC_CONNECTED state for non-SDT data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions to RRC_CONNECTED state for data transmission, then data transmission capability is improved, but power consumption and signaling overhead increase
Solution Approach 1:
The network pre-configures SDT parameters and resources for the UE before it enters RRC_INACTIVE state. This preliminary configuration enables the UE to perform small data transmissions directly in the inactive state without needing to transition to connected state, thereby reducing power consumption while maintaining data transmission capability for small packets.
Solution Approach 2:
The patent segments data transmission into two categories: small data transmissions (SDT) that can occur in RRC_INACTIVE state using pre-configured resources, and larger or more complex transmissions that require RRC_CONNECTED state. This segmentation allows the system to optimize power consumption by handling small data without full connection establishment.
2Reliability
If the UE transitions to RRC_CONNECTED state for data transmission, then data transmission capability is improved, but signaling overhead increases
Solution Approach 1:
The network performs preliminary configuration of SDT parameters, resources, and radio bearers while the UE is in connected state, before releasing it to inactive state. This preliminary action reduces signaling overhead by eliminating the need for extensive connection setup signaling when small data transmissions are needed in inactive state.
Solution Approach 2:
The patent extracts the essential data transmission functionality from the full RRC_CONNECTED state and creates a simplified SDT mechanism that operates in RRC_INACTIVE state. This extraction removes unnecessary signaling components while retaining core data transmission capability for small packets.
3Adaptability or versatility
If frequent connection setups and releases are performed, then data transmission flexibility is improved, but power consumption increases
Solution Approach 1:
The network pre-configures multiple SDT parameters including uplink grants, downlink assignments, and radio bearer configurations before the UE enters inactive state. This preliminary configuration enables flexible small data transmissions without requiring repeated connection setups, thereby reducing power consumption while maintaining adaptability.
Solution Approach 2:
The patent introduces SDT-specific parameters such as sdT-UplinkGrant, sdT-DownlinkAssignment, and sdT-RadioBearerConfig that modify the standard RRC parameters. These parameter changes enable flexible data transmission in inactive state by providing dedicated resources and configurations tailored for small data packets.
Data Source
AI summary
The present application relates to small data transmission (SDT). In an example, SDT is available for transferring information between a UE and a network, where a NAS layer of the UE is in a 5GMM-CONNECTED mode with an RRC inactive indication and an AS layer of the UE is in an RRC_INACTIVE state. To do so, the UE can be pre-configured to classify the information as qualifying for SDT. In addition, resources can be pre-configured for the SDT. For instance, the UE can maintain a set of radio bearers in a suspended state. While the NAS layer is in the 5GMM-CONNECTED mode with the inactive indication and the AS layer is in the RRC_INACTIVE state, one or more of the pre-configured resources can be used to transmit the information between the UE and the network.