DSDS UE RRC Connection Synchronization
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Solution Overview
Problem
Dual-SIM dual-standby (DSDS) user equipment (UE) devices face network synchronization issues and performance disruptions when suspending and resuming radio resource control (RRC) connections, leading to potential missed pages, dropped calls, and data transfer failures due to RRC state mismatch between the UE and the network.
Innovation Solution
Implementing methods for improved state synchronization by requesting a temporary transition to RRC Inactive state, storing connection state information at the network, and using timers to manage suspension and resumption of RRC connections, ensuring network awareness of SIM suspension status and efficient resumption without state mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DSDS UE suspends an RRC connection to accommodate higher priority activity on another SIM, then the higher priority activity can be performed, but the network becomes unsynchronized with the UE's suspension status, causing paging failures and connection issues upon resumption
Solution Approach 1:
The patent implements a feedback mechanism where the UE explicitly notifies the network of its suspension status through a suspension indication message. This feedback loop ensures the network is aware of the UE's suspension state, allowing proper synchronization during resumption and preventing paging failures. The network uses this feedback to adjust its expectations and maintain accurate state tracking.
Solution Approach 2:
The patent applies preliminary action by having the UE send a suspension indication message to the network before actually suspending the RRC connection. This advance notification allows the network to prepare for the suspension event, update its state records in advance, and ensure proper handling when the connection is resumed, thereby preventing synchronization issues.
2Speed
If the UE resumes an RRC connection without network awareness of the suspension status, then resumption can occur quickly, but RRC state mismatch occurs leading to connection failures and additional signaling overhead
Solution Approach 1:
The network performs preliminary actions by receiving and processing the suspension indication message before the actual resumption occurs. This allows the network to pre-update its state records and be ready for smooth resumption. The UE also prepares the suspension indication timing to ensure the network has processed the suspension status before resumption signaling begins.
Solution Approach 2:
The suspension indication message serves as a feedback mechanism that informs the network of the UE's suspension status. This feedback enables the network to synchronize its state records with the UE's actual state, ensuring that when resumption occurs, both sides have consistent state information, thereby preventing RRC state mismatch and connection failures.
3Device complexity
If the UE uses a single radio architecture for cost savings, then device cost and size are reduced, but network synchronization problems occur during SIM suspension and resumption operations
Solution Approach 1:
The patent implements feedback mechanisms at the protocol layer (RRC signaling) to compensate for the limitations of the single radio architecture. By having the UE explicitly signal its suspension status to the network through standardized messages, the system maintains reliable network communication despite the shared radio resource constraints inherent in single-antenna designs.
Data Source
AI summary
Devices and associated methods for operating a dual-subscriber identity module (SIM) dual-standby (DSDS) user equipment device (UE) configured with a first SIM and a second SIM. The UE performs communications with a first cellular network using the first SIM and a first radio resource control (RRC) connection, and receives a request to perform a higher priority communication using the second SIM. In response to the request to perform the higher priority communication, the UE transmits a request to the first network to suspend the first RRC connection. After transmission of the request to suspend the first RRC connection, the UE receives a message from the first network to place the first RRC connection in an inactive state, and initiates a timer, wherein the timer is used to determine whether the first RRC connection remains in the inactive state or transitions to an idle state.