Dual-SIM RRC Suspend-Resume Timing for DSDS State Alignment

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Dual-SIM dual-standby (DSDS) user equipment (UE) devices face network problems when a SIM suspends and then resumes a radio resource control (RRC) connection, leading to potential RRC state mismatches between the UE and the network.

Innovation Solution

The UE is configured to manage state synchronization with the network by transmitting requests to suspend and resume RRC connections, using timers to ensure synchronization and storing connection states at the network level for quick restoration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a SIM suspends and resumes an RRC connection in a DSDS UE, then the UE can switch between SIMs for different communications, but RRC state mismatches occur between the UE and the network

Engineering Contradiction:
ImproveSIM switching capabilityVSAvoidRRC state synchronization
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The UE transmits an RRC connection suspend request to the network before actually suspending the connection, and transmits an RRC connection resume request before resuming. This preliminary notification ensures the network is aware of the suspension/resumption actions and can maintain proper state synchronization, preventing RRC state mismatches while allowing SIM switching

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If the UE uses a single receiver architecture for cost savings and reduced size, then device complexity is reduced, but network problems occur during SIM suspend/resume operations

Engineering Contradiction:
Improvereceiver architectureVSAvoidRRC connection management
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The UE implements a feedback mechanism by transmitting suspend and resume requests to the network, allowing the network to track the RRC connection state of each SIM. This feedback loop ensures that even with a single receiver architecture, the network maintains accurate state information and can properly manage the suspend/resume operations without causing network problems

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS12214099B2User equipment having multiple subscriber identity modules with improved suspend / resume operation
Publication Date: 2025.02.04 APPLE INC
  • US12214099B2 patent drawing
  • US12214099B2 patent drawing
  • US12214099B2 patent drawing

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.