Continuity Control Function Anchoring Voice Sessions Across Cellular and WLAN
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Solution Overview
Problem
Current technologies fail to seamlessly transfer calls between cellular networks and WLANs, leading to limited mobility and control over voice sessions, as well as inadequate maintenance of call services during transfers between these networks.
Innovation Solution
Implementing a continuity control function (CCF) within a multimedia subsystem (MS) that anchors call control for both circuit-switched and packet communications, enabling seamless transfers and maintaining service control across networks by managing signaling paths and bearer paths through media gateways and service identities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If calls are transferred between cellular network and WLAN, then mobility freedom is improved, but call control and service maintenance capability deteriorates
Solution Approach 1:
The patent introduces a Continuity Control Function (CCF) as an intermediary entity that anchors call control during transfers between cellular and WLAN networks. The CCF maintains the signaling path and bearer path continuity, ensuring that call control capability is preserved even as the user moves between different network types. The CCF acts as a mediator that coordinates the handover process and maintains service continuity.
Solution Approach 2:
The patent segments the call control function into distinct components: the CCF that anchors the call, the media gateway that handles bearer paths, and the access networks (cellular/WLAN) that provide connectivity. This segmentation allows each component to specialize in its function while maintaining overall call control through the anchored CCF.
2Adaptability or versatility
If separate communication interfaces are used for cellular and WLAN, then network independence is improved, but call transfer capability deteriorates
Solution Approach 1:
The patent makes the CCF a universal control entity that can anchor calls regardless of whether the access network is cellular or WLAN. The CCF implements multi-functionality by handling both circuit-switched (CS) and packet-switched (PS) call types, and by supporting transfers between different network types through standardized interfaces and protocols.
3Reliability
If call control is anchored at CCF in MS, then service control capability is improved, but system complexity increases
Solution Approach 1:
The patent extracts the call control anchoring function from the access networks (cellular/WLAN) and concentrates it in the CCF within the multimedia subsystem. This extraction simplifies the access networks by removing complex call control logic, while the CCF provides centralized service control capability. The media gateway handles bearer path management separately, further dividing complexity into manageable components.
Data Source
AI summary
The present invention moves service control, including call control, for a user element from a cellular network to a multimedia subsystem (MS), such as the Internet Protocol (IP) Multimedia Subsystem (IMS). Call control is provided by the MS irrespective of whether the user element is using cellular or WLAN access for the call. Call control for originating and terminating calls in the CS or MS as well as transferring calls between a circuit-switched subsystem (CS) and MS is anchored at a continuity control function (CCF) in the MS. All call signaling for the call is passed through the CCF. The CCF is a service provided in the user element's home MS and anchors the user element's active CS calls and MS sessions to enable active roaming across the CS and MS.