Early Data Transmission Msg4 Loss Handling in CIoT Networks
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Solution Overview
Problem
In LTE, the Early Data Transmission (EDT) procedure for User Plane (UP) Consumer Internet of Things (CIoT) evolved packet system (EPS) is hindered when Message 4 (Msg4) is lost during cell reselection or timer expiration, leading to incorrect anchor node selection and unnecessary UE fallback to IDLE mode, limiting service applicability.
Innovation Solution
The new anchor node sends an EDT failure indication and Resume ID to the previous anchor node, enabling the UE to resume in RRC_CONNECTED mode without core network involvement, and the previous anchor forwards a new resumption request to the new anchor, ensuring correct anchoring and minimizing network impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE follows legacy EDT procedure when Msg4 is lost, then the procedure simplicity is maintained, but the service applicability is limited due to incorrect anchor node selection and unnecessary fallback to IDLE mode
Solution Approach 1:
The patent implements dynamic behavior where the UE checks whether it is in RRC_CONNECTED mode with an established data radio bearer before attempting EDT. This dynamic condition checking allows the system to adapt between different operational states (EDT continuation vs. fallback to IDLE) based on current connection status, thereby improving service applicability without permanently increasing procedure complexity
Solution Approach 2:
The patent changes the operational parameter by allowing EDT to continue in RRC_CONNECTED mode when Msg4 is lost, rather than forcing a fallback to IDLE mode. This parameter change (maintaining connection state) directly improves service applicability while the complexity increase is managed through conditional logic rather than fundamental procedural changes
2Use of energy by moving object
If the UE falls back to IDLE mode upon Msg4 loss, then the network state is simplified, but power consumption increases and service continuity is disrupted
Solution Approach 1:
The patent performs preliminary checking of the RRC connection state and data radio bearer establishment status before determining the EDT outcome. By proactively verifying these conditions, the system can prevent unnecessary fallback to IDLE mode, thereby reducing power consumption while maintaining service continuity through early detection of suitable EDT continuation scenarios
Solution Approach 2:
The patent implements feedback mechanisms where the UE monitors its own connection state (RRC_CONNECTED status and data radio bearer establishment) and uses this feedback to determine whether to continue EDT or fallback to IDLE. This self-feedback loop enables energy-efficient operation by maintaining connected state only when appropriate, while ensuring service continuity through condition-based decision making
3Productivity
If the anchor node selection is performed without considering Msg4 delivery status, then the procedure speed is maintained, but the network efficiency deteriorates due to incorrect anchoring
Solution Approach 1:
The patent performs preliminary verification of Msg4 delivery status and RRC connection state before finalizing the EDT procedure outcome. This preliminary check ensures that anchor node selection is based on accurate delivery information, improving network efficiency without significantly impacting procedure speed because the check is integrated into the existing EDT flow rather than being an additional sequential step
Data Source
AI summary
Technology is disclosed for an evolved node B (eNB) operable for early data transmission (EDT) in a user plane (UP) in a cellular internet of things (CIoT) evolved 5 packet system (EPS) network. The eNB can be configured to encode, at the eNB for transmission to a user equipment (UE), a message 4 (Msg4) including a resume identifier (ID) and a next-hop chaining count (NCC). The eNB can be configured to determine, at the eNB, a delivery status of the Msg4 to the UE. The eNB can be configured to encode, at the eNB for transmission to a previous eNB of the UE, one or more of an EDT failure 10 indicator or the resume ID.