Small Data Transmission in RRC_INACTIVE for Low-Latency NR Access
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing low transmission latency and high data rate requirements, particularly in transitioning between RRC_INACTIVE and RRC_CONNECTED states for small data transmissions, leading to network overhead and inefficiency.
Innovation Solution
A method and apparatus for implementing NR cell access that includes transmitting UE Capability Information to the base station, supporting type 1 and type 2 SDT, and performing cell selection and RRC connection resume procedures to enable small data transmission (SDT) without transitioning to RRC_CONNECTED state, utilizing configured grants and random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal transitions to RRC_CONNECTED state for data transmission, then data transmission reliability is improved, but transmission latency increases and network overhead increases
Solution Approach 1:
The network pre-configures SDT resources (configured grants, random access resources) and SDT parameters in the RRC_INACTIVE state before data transmission is needed. This preliminary configuration allows the terminal to immediately transmit small data without state transition, resolving the contradiction by preparing everything in advance so no time is lost during actual transmission.
Solution Approach 2:
The system dynamically selects between SDT and traditional RRC_CONNECTED transmission based on data size and QoS requirements. For small data, SDT is used to minimize latency; for larger or more complex data, RRC_CONNECTED provides full reliability. This dynamic adaptation resolves the contradiction by matching the transmission method to the specific requirements.
2Productivity
If the terminal transitions to RRC_CONNECTED state for data transmission, then data transmission capability is improved, but network overhead increases
Solution Approach 1:
The invention extracts the essential data transmission functionality from the full RRC_CONNECTED state, creating a simplified SDT mechanism that operates within RRC_INACTIVE. By taking out only the necessary transmission capabilities and leaving behind the full state management overhead, the system achieves data transmission without the associated network overhead of complete state transitions.
Solution Approach 2:
Instead of performing the complete RRC state transition action, the system performs a partial action by transmitting only small data packets through SDT resources while remaining in RRC_INACTIVE state. This partial transmission approach provides sufficient capability for small data while avoiding the excessive overhead of full connection establishment.
3Loss of time
If the terminal remains in RRC_INACTIVE state for small data transmission, then transmission latency is reduced and network overhead is reduced, but transmission reliability may be compromised
Solution Approach 1:
The SDT mechanism acts as an intermediary solution between RRC_INACTIVE and RRC_CONNECTED states. It provides a middle ground that maintains the low overhead and low latency benefits of RRC_INACTIVE while incorporating sufficient transmission capabilities to achieve acceptable reliability for small data, thus mediating between the two extremes.
Solution Approach 2:
The system changes key transmission parameters (data size thresholds, QoS requirements, resource allocation) to optimize for both latency and reliability simultaneously. By adjusting these parameters based on specific transmission needs, the system achieves low latency through SDT while maintaining sufficient reliability through appropriate resource configuration and selection.
Data Source
AI summary
A Method and Apparatus for performing small data transmission is provided. The method includes transmitting UECapabilityInformation to the base station, The UECapabilityInformation includes type 1 SDT support information and type 2 SDT support information, transmitting a message containing the UE NETWORK CAPACITY to the AMF, Specific bits in the UE NETWORK CAPABILITY indicate whether RRC CONNECTION RESUME3 is supported, receiving an RRCRelease from the base station, The RRCRelease comprises a SuspendConfig, In response to receiving said RRCRelease message, entering the RRC_INACTIVE state and performs cell selection, monitoring the paging channel in the selected cell, and initiating RRC CONNECTION RESUME3 or performing the first set of actions upon receiving a first paging message or a third paging message.