Dual-SIM RRC Suspend-Resume Synchronization for DSDS User Equipment
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Solution Overview
Problem
Dual-SIM dual-standby (DSDS) UE devices experience network synchronization issues and inefficiencies when suspending and resuming radio resource control (RRC) connections, leading to missed pages, dropped calls, and data transfer failures due to RRC state mismatch between the UE and the network.
Innovation Solution
The UE devices implement methods to synchronize RRC states by transmitting requests to suspend or resume RRC connections with a timer and providing messages to the network, ensuring the network maintains the connection context, thereby avoiding state mismatches and improving communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE suspends RRC connection on the first SIM to handle higher priority communication on the second SIM, then the higher priority communication can be performed, but the network synchronization state is lost leading to missed pages and dropped calls
Solution Approach 1:
The UE transmits an RRC connection suspend request message to the network before actually suspending the connection, as a preliminary action to inform the network of the upcoming suspension. This allows the network to prepare for the suspension and maintain proper state synchronization, preventing missed pages and dropped calls while still enabling the higher priority communication on the second SIM.
2Speed
If the UE resumes RRC connection quickly after suspending, then communication can be restored, but the network may not have properly updated its state leading to state mismatch
Solution Approach 1:
The UE implements a feedback mechanism where it waits to receive an RRC connection suspend acknowledgment message from the network before actually resuming the connection. This feedback loop ensures that the network has properly updated its state and is synchronized with the UE, preventing state mismatches while maintaining efficient connection restoration.
3Reliability
If the UE maintains RRC connection active during high priority communication on the other SIM, then network synchronization is maintained, but radio resources are wasted and energy is consumed
Solution Approach 1:
The UE sends a suspend request as preliminary action before actually suspending the RRC connection, allowing the network to prepare for the suspension. This preliminary notification enables the UE to safely suspend the connection and save radio resources and energy, while the network is already prepared to handle the suspension properly, maintaining synchronization without continuous resource consumption.
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.