RRC Reconfiguration Synchronization Using a Second UE Identity
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Solution Overview
Problem
In LTE networks, the uncertainty in determining when a user equipment (UE) has completed a reconfiguration procedure leads to potential connectivity loss due to asynchronous configuration changes, especially with transmission errors in RRC reconfiguration messages.
Innovation Solution
Associate a new configuration with a second UE identity, allowing the radio base station to identify when the UE has activated the new configuration by detecting responses using this identity, eliminating the need for an activation time and reducing timing uncertainty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an activation time is used to synchronize reconfiguration between UE and radio base station, then simultaneous configuration activation is achieved, but reconfiguration delay increases and timing uncertainty remains
Solution Approach 1:
The patent implements a feedback mechanism where the UE sends an acknowledgment message containing a second UE identity to confirm successful reconfiguration. The radio base station uses this feedback to determine when the new configuration is active, replacing the blind activation time approach with confirmed synchronization.
Solution Approach 2:
The patent introduces a second UE identity as an intermediary element that bridges the configuration activation process. This second identity serves as a marker that allows the base station to identify and confirm when the UE has successfully activated the new configuration, eliminating the need for timing-based synchronization.
2Reliability
If transmission errors occur in RRC reconfiguration messages, then configuration synchronization is lost, but retransmission increases delay
Solution Approach 1:
The feedback mechanism allows the base station to confirm successful configuration activation before proceeding. If transmission errors occur, the base station can detect the failure through lack of acknowledgment and initiate retransmission only when necessary, avoiding unnecessary delays from blind retransmissions.
Solution Approach 2:
Instead of always transmitting reconfiguration messages with full redundancy, the system uses selective retransmission based on feedback. The base station transmits the reconfiguration message once and only retransmits if the acknowledgment is not received, reducing overall delay while maintaining reliability.
3Productivity
If the radio base station uses a first UE identity for scheduling, then existing scheduling continues, but it cannot detect when UE activates new configuration
Solution Approach 1:
The second UE identity acts as an intermediary marker that allows the base station to track configuration activation status without disrupting existing scheduling operations. The base station continues to use the first UE identity for normal scheduling while using the second identity to detect and confirm configuration activation events.
Solution Approach 2:
The patent changes the identification parameter from a single static UE identity to a dynamic system where the UE identity changes based on configuration activation. When the UE activates a new configuration, it switches to using the second UE identity for scheduling, providing the base station with visible status information.
Data Source
AI summary
A procedure for synchronization of re-configuration of RRC procedures between the radio base station and the UE is achieved by associating a new configuration to be used by a UE with an additional UE identity. The UE is normally identified by a first UE identity, but is informed in a re-configuration message that the UE also has the additional UE identity. The UE is identified by the additional UE identity when the new configuration is to be activated. Hence, when the radio base station detects that the UE responds to requests, which included the additional UE identity, the radio base station can conclude that the UE has activated the new configuration.