RRC Connection Resume with NAS Message Filtering
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently resuming suspended RRC connections and defining clear operations for UE, eNB, and MME in handling initial NAS messages, particularly in scenarios without an accept response, leading to resource inefficiencies and potential connection failures.
Innovation Solution
A method for resuming a suspended RRC connection involves entering an EPS Mobility Management-IDLE mode with a suspend indication, generating an initial NAS message, and switching to EMM-CONNECTED mode upon successful resume indication, with specific message types and procedures to manage accept and reject responses from the MME, ensuring efficient resource management and connection recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transmits initial NAS messages to the MME after RRC connection resume, then the connection recovery is complete, but resource wastage occurs when the MME sends reject responses for messages without accept responses
Solution Approach 1:
The UE checks whether the initial NAS message type requires an accept response from the MME before transmitting the message. This preliminary check prevents unnecessary message transmissions and avoids the MME sending reject responses, thereby recovering connections reliably while preventing resource wastage.
Solution Approach 2:
The patent introduces an intermediary checking mechanism that mediates between the UE's connection resume request and the MME's response. By filtering messages based on their accept response requirements, this intermediary layer prevents unnecessary reject responses from being sent, reducing resource wastage while maintaining connection recovery reliability.
2Productivity
If the UE switches to EMM-CONNECTED mode upon RRC connection resume indication, then connection efficiency is improved, but operational ambiguity arises without clear definitions for handling initial NAS messages
Solution Approach 1:
The patent segments initial NAS messages into two categories: those that require accept responses from the MME and those that do not. This segmentation allows the UE to switch to EMM-CONNECTED mode efficiently while following clear operational rules for each message type, eliminating operational ambiguity.
Solution Approach 2:
The patent changes the operational parameter by introducing a new state indicator (suspend indication) and modifying the message transmission logic based on message type. This allows efficient connection resume while providing clear operational definitions for handling different initial NAS messages in the EMM-CONNECTED mode.
3Device complexity
If the MME sends reject responses for initial NAS messages without accept responses, then message handling is simplified, but resource inefficiency and connection failures increase
Solution Approach 1:
The UE performs a preliminary check on the initial NAS message type to determine whether an accept response is required before transmission. This prevents the MME from receiving and processing messages that would result in reject responses, simplifying message handling while eliminating resource inefficiency.
Solution Approach 2:
The patent converts the potential harm of unnecessary reject responses into a benefit by implementing a pre-transmission check mechanism. This mechanism identifies and filters out messages that would generate reject responses, transforming what could be a harmful resource waste into a beneficial optimization of the connection resume process.
Data Source
AI summary
A method for resuming an RRC connection performed by a UE in a wireless communication system may include entering an EMM-IDLE mode with a suspend indication as the RRC connection is suspended; generating an initial NAS message when a procedure using the initial NAS message is triggered; requesting a resume of the RRC connection from an upper layer of the UE to a lower layer; and switching from the EMM-IDLE mode with the suspend indication to an EMM-CONNECTED mode when the upper layer receives an indication that the RRC connection is resumed from the lower layer.