MSG3 Early Data Retransmission Signaling After Cell Reselection
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Solution Overview
Problem
During early data transmission (EDT), terminal devices in idle, suspend, or inactive states may perform cell reselection, leading to delivery failures of downlink early data, increased signaling load, and resource waste due to repeated receptions of uplink early data.
Innovation Solution
The terminal device transmits an uplink message with a first MSG3 carrying indication information to indicate whether the uplink early data is retransmission data, allowing the core network to reserve or discard the data accordingly, reducing signaling load and resource waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminal device performs cell reselection during early data transmission, then the terminal device can access a better cell or maintain connectivity, but delivery failure of downlink early data occurs and signaling load increases
Solution Approach 1:
The terminal device includes indication information in the first MSG3 to preemptively inform the core network about retransmission data status before the network processes the data. This preliminary action allows the network to prepare appropriate handling (reserve or discard) in advance, preventing delivery failures and reducing subsequent signaling operations.
Solution Approach 2:
The indication information acts as an intermediary element between the terminal device and core network, carrying critical status information about the uplink early data. This intermediary enables the network to make informed decisions about data handling without requiring additional communication rounds, thus reducing signaling load while maintaining reliability.
2Reliability
If terminal device re-initiates random access procedure after cell reselection, then the terminal device can re-establish connection, but repeated reception of uplink early data occurs at core network leading to resource waste
Solution Approach 1:
The indication information is included in the first MSG3 to preemptively inform the core network about retransmission data status before the network processes the data. This preliminary action allows the network to prepare appropriate handling (reserve or discard) in advance, preventing delivery failures and reducing subsequent signaling operations.
Solution Approach 2:
When the indication information signals that the uplink early data is retransmission data, the core network discards the duplicate data to avoid resource waste. This selective discarding mechanism prevents the network from storing and processing repeated copies of the same data, thereby conserving network resources while maintaining connection reliability.
Data Source
AI summary
Data transmission methods and a communication device are provided. The method includes the following. A terminal device transmits an uplink message, where the uplink message includes a first message 3 (MSG3) for accessing a first cell, and the first MSG3 includes uplink early data stored in non-access stratum (NAS) information, or the uplink message includes the first MSG3 for accessing the first cell and the uplink early data. The first MSG3 carries indication information, and the indication information indicates whether the uplink early data is retransmission data.