NAS-AS Interaction for Early Data Transmission in Wireless Devices
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Solution Overview
Problem
Current 3GPP technologies face challenges in early data transmission (EDT) due to the lack of user data size information at the RRC layer during RRC connection establishment, preventing the initiation of control plane EDT (CP-EDT) procedures.
Innovation Solution
The proposed solution ensures that the necessary information and user data for EDT are available at the RRC layer by mandating the provision of a non-access stratum (NAS) protocol data unit (PDU) containing uplink user data to the access stratum (AS) layer before transmission in Msg3, allowing the RRC layer to determine the initiation of EDT based on the PDU size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RRC layer waits for NAS signaling connection establishment before obtaining user data size information, then the NAS-AS interaction follows the traditional sequential procedure, but the EDT initiation is delayed and cannot occur in Msg3
Solution Approach 1:
The patent applies preliminary action by having the NAS layer provide user data size information to the RRC layer before the RRC connection establishment is fully completed. Specifically, the NAS layer provides this information in advance during the RRCConnectionSetupRequest or RRCConnectionResumeRequest message preparation, enabling the RRC layer to determine EDT eligibility and initiate EDT in Msg3 without waiting for the traditional sequential NAS signaling connection establishment to complete first.
2Productivity
If the NAS layer provides user data size information earlier to the RRC layer, then the EDT initiation can occur in Msg3, but the NAS-AS interaction complexity increases
Solution Approach 1:
The patent applies merging by combining the user data size information provision with the existing RRC connection establishment signaling flow. The NAS layer provides the user data size information within the context of the RRCConnectionSetupRequest or RRCConnectionResumeRequest message preparation process, rather than requiring a separate information exchange mechanism. This integration approach enables EDT initiation in Msg3 while minimizing additional interaction complexity.
3Speed
If the RRC layer determines EDT initiation without having user data size information, then the procedure can progress faster, but the EDT determination accuracy is reduced
Solution Approach 1:
The patent resolves this contradiction by having the NAS layer perform preliminary action to provide user data size information to the RRC layer at the appropriate moment during message preparation. This ensures the RRC layer has accurate information for EDT determination while maintaining procedural speed, as the information is provided in advance during the RRCConnectionSetupRequest or RRCConnectionResumeRequest preparation rather than requiring the RRC layer to wait or make delayed determinations.
Data Source
AI summary
According to some embodiments, a method for early data transmission performed by a wireless device comprises: obtaining, from a non-access stratum (NAS) communication layer, an initial NAS protocol data unit (PDU) for early data transmission; determining, by a radio resource control (RRC) communication layer, to initiate early data transmission based at least in part on a size of the initial NAS PDU; and transmitting an early data transmission including the initial NAS PDU.