Remote UE PC5-S Message Handling for RRC Latency Reduction
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Solution Overview
Problem
Existing wireless communication systems experience unnecessary latency in RRC connection establishment for remote UE due to the need for remote UE to wait for an RRC connection establishment control timer to expire before transitioning to an idle state and re-initiating the connection, especially when access is barred or an RRC connection reject message is received.
Innovation Solution
The remote UE processes PC5-S and PC5-RRC messages to determine the RRC state and either stop timers T300/T319 or initiate RRC connection re-establishment procedures, allowing it to transition to an idle state or re-establish the connection without waiting for the timer to expire, thereby reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the remote UE waits for the RRC connection establishment control timer to expire before transitioning to idle state and re-initiating connection, then the connection establishment procedure follows the standard protocol flow, but unnecessary latency is introduced to the RRC connection establishment process
Solution Approach 1:
The remote UE performs preliminary actions by stopping the T300/T319 timer immediately upon receiving the PC5-S message indicating access barring or RRC connection establishment failure, rather than waiting for the timer to expire naturally. This preliminary intervention eliminates unnecessary waiting time and enables faster transition to idle state and re-initiation of connection establishment procedure
Solution Approach 2:
The remote UE autonomously determines its own state transition and timer management based on the received PC5-S message content. The device independently decides to stop the timer and transition to idle state without requiring external control or waiting for standard protocol timeouts, thereby reducing latency while maintaining protocol compliance
2Productivity
If the remote UE immediately transitions to idle state upon receiving access barring information without waiting for timer expiration, then connection establishment latency is reduced, but the protocol state machine consistency may be compromised
Solution Approach 1:
The remote UE uses feedback from the received PC5-S message (indicating access barring or RRC connection establishment failure) to adjust its timer management and state transition behavior. The feedback mechanism allows the device to respond appropriately to network conditions while maintaining protocol state consistency through defined state transition rules
Solution Approach 2:
The remote UE changes the timer parameter state by stopping T300/T319 upon receiving the PC5-S message, rather than allowing it to continue running to expiration. This parameter change triggers the state transition to idle state and enables faster re-initiation of connection establishment while maintaining protocol compliance
Data Source
AI summary
The present invention provides a processing method for remote user equipment and user equipment. The processing method for remote UE comprises the following steps: receiving, by the remote UE, a PC5-S message from relay UE, wherein the PC5-S message is a message or signaling transmitted on a PC5 non-access stratum; and performing, by the remote UE upon receiving the PC5-S message, the following operation on the basis of an RRC state of the remote UE: when the remote UE is in an idle/inactive state and a timer T300/T319 is running, the remote UE stops the timer T300/T319; when the remote UE is in a connected state, the remote UE starts/initiates an RRC connection re-establishment procedure.