UE Small Data Transmission in Inactive State via Pre-stored Identifier
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Solution Overview
Problem
User Equipment (UE) operating in an inactive state faces challenges in identifying itself to a base station during random access procedures, particularly in scenarios where it does not have a cell radio network temporary identifier (C-RNTI), hindering efficient small data transmission.
Innovation Solution
The UE transmits a message, such as an RRCResumeRequest, using a configured grant, and detects uplink data within a predetermined interval, then performs a random access procedure with an indication of the uplink data and a previously obtained identifier, allowing it to proceed without waiting for a random access response including a temporary C-RNTI, and optionally receives an identifier from the base station or uses a dedicated RNTI for communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE uses a temporary C-RNTI obtained through random access procedure to transmit data in inactive state, then the UE can be identified by the base station, but the UE must wait for random access response which increases transmission delay
Solution Approach 1:
The UE performs preliminary actions by obtaining and storing its identifier (C-RNTI or I-RNTI) before entering the inactive state. When small data needs to be transmitted, the UE can directly use this pre-obtained identifier in the RRCResumeRequest message, eliminating the need to wait for random access response to obtain a temporary identifier, thus reducing transmission delay while maintaining reliable identification
2Reliability
If the UE performs random access procedure to obtain temporary C-RNTI before data transmission, then the UE can be properly identified, but the procedure complexity increases
Solution Approach 1:
The invention extracts the identifier acquisition step from the random access procedure. Instead of requiring the complete random access procedure to obtain a temporary C-RNTI, the UE extracts and uses its existing identifier (C-RNTI or I-RNTI) that was obtained during connection establishment or suspension, thereby simplifying the procedure while maintaining proper identification
3Productivity
If the UE transmits data immediately in inactive state without obtaining temporary C-RNTI, then transmission efficiency improves, but the base station cannot properly identify the UE
Solution Approach 1:
The UE serves itself by using its own existing identifier (C-RNTI or I-RNTI) for identification purposes. Instead of relying on the base station to assign a temporary identifier through random access procedure, the UE self-provides its identifier in the RRCResumeRequest message, enabling both immediate transmission and reliable identification
Data Source
AI summary
A method in a user equipment (UE) for communicating with a base station includes receiving (602), from the base station, a configured grant for the UE to utilize when operating in an inactive state associated with a protocol for controlling radio resources. The method also includes transmitting (604), when the UE is in the inactive state, a message to the base station using the configured grant and detecting (606), within a predetermined interval after transmitting the message, uplink data addressed to the base station. The method further includes, in response to the detecting, performing (608) a random access procedure with the base station, including transmitting a payload with (i) an indication of the uplink data and (ii) an identifier of the UE obtained by the UE prior to performing the random access procedure.