Seamless Cellular to WLAN Handover via Trusted S2a Interface
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Solution Overview
Problem
Current mobile devices experience disruptions and data interruptions during handovers from cellular to WLAN networks due to non-seamless connectivity transitions, which are unacceptable for applications like streaming video or VoIP, as they involve changes in IP addresses, leading to potential network interruptions.
Innovation Solution
Implementing a seamless handover method that maintains the same IP address across both cellular and WLAN networks by using trusted WLANs that support an S2a interface with the cellular network, allowing for continuous data flow and authentication through a common packet data network gateway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-seamless handover is used to switch from cellular to WLAN network, then device can connect to WLAN network, but IP address changes causing data interruption and network disruption
Solution Approach 1:
The system performs preliminary actions by establishing a PDN connection through the WLAN access network before actually switching from cellular to WLAN. This pre-establishment of the packet data network connection ensures that the IP address is allocated and ready, allowing seamless handover without data interruption when the network switch occurs.
Solution Approach 2:
The patent introduces an intermediary mechanism - the PDN connection establishment process - that acts as a bridge between cellular and WLAN networks. By using the WLAN access network to establish the PDN connection first, the system creates a smooth transition path that maintains IP address consistency and prevents data transmission disruptions during network handover.
2Reliability
If seamless handover is implemented to maintain IP address consistency, then data transmission continuity is improved, but system complexity increases due to S2a interface requirements
Solution Approach 1:
The system applies universality by making the WLAN access network multi-functional - it serves both as a standard wireless access point and as an S2a interface endpoint that can establish PDN connections. This allows the same WLAN infrastructure to provide both regular internet access and seamless handover capability, reducing the need for separate dedicated seamless handover hardware or software components.
3Adaptability or versatility
If application-layer solutions are used to handle IP address changes, then network compatibility is maintained, but user experience deteriorates due to repeated connection re-establishment
Solution Approach 1:
The patent ensures continuity of useful action by maintaining the same IP address throughout the handover process from cellular to WLAN networks. Since the PDN connection is established before the network switch and the IP address remains consistent, data transmission continues without interruption and applications don't need to re-establish connections, providing a seamless user experience.
Data Source
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AI summary
Methods and apparatus for determining if seamless handover is required for mobile device network connections are disclosed. In one such method, a mobile device establishes connectivity to a public data network (PDN) via a cellular network, determines the availability of a plurality of wireless local area networks ("WLANs"), at least one member of the plurality of WLANs providing connectivity to the PDN, and determines if a condition requiring seamless handover is present. If the condition requiring seamless handover is present, then the mobile device selects, from the plurality of WLANs, a trusted WLAN as the handover WLAN, the trusted WLAN being a WLAN that provides connectivity to the PDN.