IMS Session Continuity Across 4G and 5G Access Networks
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Solution Overview
Problem
Current systems face challenges in maintaining IMS session continuity when a wireless device transitions between 4G and 5G networks, often requiring new IMS registrations and IP address changes, which can disrupt ongoing communications and services like VoLTE/ViLTE.
Innovation Solution
The solution involves methods and apparatus that enable simultaneous connectivity to both 4G and 5G networks, allowing a single IMS signaling path to be maintained across different access technologies without triggering new IMS registrations, even when a new IP address is acquired, by sharing a single IP address or allowing different IP addresses while keeping the IMS signaling path consistent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wireless device transitions between 4G and 5G networks, then network connectivity is improved, but IMS session continuity deteriorates due to required re-registrations and IP address changes
Solution Approach 1:
The system performs preliminary actions by establishing event reporting subscriptions with the PCRF before network transitions occur. The P-CSCF subscribes to IP-CAN type change events and RAT type change events, so that when a transition between 4G and 5G occurs, the system is already prepared to maintain session continuity through pre-configured event monitoring and response mechanisms.
Solution Approach 2:
The PCRF acts as an intermediary between the P-CSCF and the network access layers. It receives event reports from the network about IP-CAN type changes or RAT type changes, and communicates these events to the P-CSCF, which then maintains the IMS session without requiring re-registration. This intermediary mechanism decouples the IMS session management from the underlying network technology changes.
2Adaptability or versatility
If a new IP address is acquired during network transition, then network adaptability is improved, but IMS session stability deteriorates due to IP address changes
Solution Approach 1:
The PCRF serves as an intermediary that monitors IP-CAN type changes and communicates these events to the P-CSCF. The P-CSCF uses this information to maintain IMS session stability even when IP addresses change during network transitions, by understanding that the session should persist across different IP-CAN types and IP addresses.
Solution Approach 2:
The system accepts and adapts to parameter changes in the IP address and IP-CAN type while maintaining the IMS session. The event reporting mechanism allows the system to detect when IP address parameters change and automatically adjust without requiring session termination or re-registration, thus maintaining stability through controlled adaptation to parameter changes.
3Adaptability or versatility
If IMS re-registration is triggered during network transition, then network connectivity is maintained, but service disruption increases
Solution Approach 1:
The system performs preliminary actions by establishing event reporting subscriptions before network transitions. The P-CSCF is pre-configured to receive notifications about IP-CAN type changes and RAT type changes, allowing it to maintain sessions without triggering re-registrations. This preliminary setup prevents service disruption by having the response mechanism ready in advance.
Solution Approach 2:
The event reporting mechanism provides feedback from the network to the P-CSCF about upcoming or occurring network transitions. The PCRF monitors network conditions and sends event reports to the P-CSCF, which then takes appropriate actions to maintain session continuity without requiring re-registration, thus eliminating service disruption through informed, feedback-driven decision making.
Data Source
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AI summary
Systems and methods relating to providing Data Network (IMS) session continuity across 4G access and 5G access and core networks are disclosed. In some embodiments, a method of operation of a wireless device comprises establishing over a first access network (e.g., 4G) a first packet data connection to a packet data network (e.g., IMS) identified by a first packet data network identifier (e.g., APN), performing a registration with an application entity (P-CSCF) of the packet data network; and sending over a second access network (5G) a request for a second packet data connection to the packet data network (IMS) identified by a second packet data network identifier (e.g., DNN) wherein the request comprises an identifier of the application entity (P-CSCF) of the packet data network with which the wireless device has previously registered. The request for the second packet data connection may comprise the DN public identifier (i.e., the IMS public identifier) used in the registration with the DN (IMS) and may optionally request for linking the second packet data connection to the first packet data connection in such a way that will allow control of simultaneous access to the DN over 4G and 5G. A common or different IP address may be assigned to the first packet data connection and the second packet data connection. Similar methods are provided on the policy control entity and the user plane control entity. In this manner, simultaneous access of a wireless device over 4G and 5G can be controlled.