LTE-WiFi Mobility Architecture With S1a Interfaces for Seamless Handover

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for integrating cellular and WiFi networks result in resource-intensive operations and frequent interruptions in ongoing communications, particularly in scenarios involving inter-system mobility.

Innovation Solution

Implementing an S1a-C control plane interface between a trusted WLAN access network (TWAN) and a mobility management entity (MME) and an S1a-U user plane interface between the TWAN and a serving gateway (SGW) in the 3GPP core network, allowing for seamless handover and simultaneous dual connectivity between LTE and TWAN access networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing methods of integrating cellular and WiFi networks are used, then inter-system mobility is supported, but resource consumption increases and communication interruptions occur

Engineering Contradiction:

Improvecommunication continuityVSAvoidnetwork resource consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent segments the integration architecture by introducing separate control plane (S1a-C) and user plane (S1a-U) interfaces between TWAN and EPC. This segmentation allows independent optimization of control signaling and data traffic, reducing overall resource consumption while maintaining communication continuity during mobility events.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces the TWAN as an intermediary network that bridges cellular and WiFi domains. The TWAN with its dedicated S1a interfaces acts as a mediator that simplifies inter-system handovers by providing a direct control plane connection to the MME, thereby reducing resource consumption and preventing communication interruptions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If existing inter-system integration methods are implemented, then access to both cellular and WiFi networks is enabled, but handover delays and communication interruptions increase

Engineering Contradiction:

Improvehandover speedVSAvoidhandover delay

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The patent establishes the control plane interface (S1a-C) and user plane interface (S1a-U) in advance before handover is needed. By pre-configuring these interfaces between TWAN and EPC, the system eliminates the need for time-consuming interface establishment during actual handover events, thereby reducing handover delays and improving handover speed.

Inventive Principle:

Principle #10Preliminary action

3Extent of automation

If core network signaling is extensive, then comprehensive control is achieved, but latency increases and scalability decreases

Engineering Contradiction:

Improvecontrol plane managementVSAvoidsignaling latency

Core Design Contradiction:

Extent of automationVSLoss of time

Solution Approach 1:

The patent extracts control plane functions by establishing a dedicated S1a-C interface between TWAN and MME, separating control signaling from user data plane. This extraction allows streamlined control plane management with reduced signaling latency, while comprehensive automation is maintained through direct MME access for mobility management decisions.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12587825B2Inter-system mobility in integrated wireless networks

Publication Date: 2026.03.24 INTERDIGITAL PATENT HOLDINGS INC

AI summary

A system is disclosed for providing inter-system mobility in integrated LTE and WiFi systems. A control plane interface, referred to as the S1a-C interface, is defined between a trusted WLAN access network (TWAN) and a mobility management entity (MME) comprised in an LTE wireless access network. A user plane interface, referred to as the S1a-U interface, is defined between the TWAN and a server gateway (SGW) in the LTE wireless access network. The MME operates as a common control plane entity for both LTE and TWAN access, while the SGW operates as a user plane gateway for both LTE and TWAN. The integrated MME and SGW allow for user equipment (UE) to access the capabilities of a packet data network (PDN) through either the LTE access network or TWAN.