Multi-SIM Control Plane With Shared AMF to Cut Signaling

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Solution Overview

Problem

Existing multi-SIM devices experience redundant signaling due to each SIM being treated as an independent UE, leading to inefficient mobility management and network operations.

Innovation Solution

Implementing a control plane mechanism that registers multiple SIMs within a single multi-SIM device with a common mobility management function, allowing them to share a single Access and Mobility Management Function (AMF) and utilize a unified Global Unique Temporary Identifier (GUTI) to minimize redundant signaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If each SIM is treated as an independent UE, then each SIM can establish independent network connections, but redundant signaling occurs during mobility management

Engineering Contradiction:
Improveindependent network connection capabilityVSAvoidredundant signaling
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent merges multiple SIMs into a single multi-SIM device identity for mobility management purposes. The network assigns a single GUTI to the multi-SIM device, and a single AMF handles mobility management for all SIMs, eliminating redundant signaling while preserving individual SIM identities for authentication and service-specific operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the network management functions into two layers: (1) device-level mobility management where the multi-SIM device is treated as a single entity with one GUTI and one AMF, and (2) SIM-level identity management where each SIM maintains its own identity for authentication and service-specific operations.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If each SIM is treated as an independent UE, then network connections can be established independently, but device complexity increases

Engineering Contradiction:
Improvedual-SIM dual-standby functionalityVSAvoidmultiple AMF assignments
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple SIM management functions into a single AMF for mobility management. The network recognizes the multi-SIM device as one logical entity, assigning a single GUTI and single AMF, thereby reducing network-side complexity while maintaining the device's ability to manage multiple SIMs independently for different services.

Inventive Principle:
Principle #5Merging (Combining)

3Loss of energy

If a unified GUTI is used for multiple SIMs, then signaling is reduced, but SIM identity differentiation becomes challenging

Engineering Contradiction:
Improvesignaling overheadVSAvoidSIM identity distinction
Core Design Contradiction:
Loss of energyVSLoss of information

Solution Approach 1:

The patent segments identity management into two levels: (1) device-level GUTI for mobility management signaling, and (2) SIM-level individual identities (IMSI, SUPI) stored and managed within the device and accessible to the network when needed for authentication and service-specific operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses the multi-SIM device itself as an intermediary that maintains the mapping between the unified GUTI and individual SIM identities. The device can present specific SIM identities to the network when required for authentication or service operations, while the network uses the unified GUTI for mobility management.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4066590B1Control plane for multi-SIM devices
Publication Date: 2026.03.04 APPLE INC
  • EP4066590B1 patent drawingFigure 1
  • EP4066590B1 patent drawingFigure 2
  • EP4066590B1 patent drawingFigure 3

AI summary

A user equipment (UE) includes a first subscriber identification module (SIM) and a second SIM. The UE is configured to establish a first cellular network connection based on, at least, the first SIM and a second cellular network connection based on, at least, the second SIM. The UE sends, by the first SIM, a first registration request to the network, wherein the first registration request comprises an identification indicating the multi-SIM device is a type of multi-SIM device, receives, by the first SIM, a first registration accept message indicating the first registration request has been accepted, wherein the first registration accept message comprises a first temporary identification for the first SIM and sends, by the second SIM, an access network message comprising one of the first temporary identification or a further temporary identification based on, at least, the first temporary identification.