CSCF Propagating RAT Change Notifications for Charging and Codec Adaptation
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Solution Overview
Problem
Current systems lack mechanisms to dynamically change codecs or charging regimes when a user equipment switches between different Radio Access Technologies (RAT) during a communication session, especially between Wi-Fi, LTE, and circuit-switched networks, without relying on new signaling from the user equipment.
Innovation Solution
A mechanism is implemented within the Call Session Control Function (CSCF) to notify and propagate Radio Access Technology (RAT) changes to relevant network nodes, allowing for automatic adjustments in charging schemes and codec changes by indicating capability and requirement for RAT change notifications through SIP messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the user equipment sends a new SIP INVITE message to trigger codec or charging regime changes upon RAT change, then the mechanism is simple and effective, but there are serious trust issues in allowing the user equipment to initiate a change in charging regime
Solution Approach 1:
Instead of allowing the user equipment to initiate charging regime changes (which creates trust issues), the patent inverts the approach by having the network node initiate and control the charging regime changes based on RAT change notifications. The user equipment only reports RAT changes, but the network node decides and executes the charging regime changes, eliminating trust issues while maintaining simplicity.
Solution Approach 2:
The patent introduces an intermediary mechanism where the network node acts as a mediator between the user equipment and the charging system. The user equipment reports RAT changes to the network node, which then independently decides and executes charging regime changes. This intermediary approach resolves the trust issue by preventing direct user equipment control over charging while maintaining the simplicity of the reporting mechanism.
2Device complexity
If charging differentiation is limited to the type of network in which the call originates, then the system is simple to implement, but there is no mechanism to apply charging differentiation based on access mobility between Wi-Fi, LTE and circuit switched legacy networks
Solution Approach 1:
The patent applies dynamics by making the charging regime adaptive and changeable during the communication session based on RAT changes. Instead of static charging differentiation only at call origin, the system dynamically adjusts charging regimes as the user equipment moves between different access networks (Wi-Fi, LTE, circuit switched), enabling versatile charging differentiation while managing complexity through standardized notification mechanisms.
Solution Approach 2:
The patent changes the parameter of charging differentiation from being static (based only on origin network) to being dynamic (based on current RAT). By introducing RAT change notifications and corresponding charging regime changes, the system enables versatile charging differentiation across multiple networks while maintaining implementation simplicity through parameter changes rather than structural complexity.
3Device complexity
If there is no mechanism to trigger a codec change in response to a RAT change, then the system is simple, but certain parameters related to a communication session set up for one RAT are not optimal when the session is moved to another technology
Solution Approach 1:
The patent applies preliminary action by pre-establishing the mechanism for RAT change notification and codec adaptation before actual RAT changes occur. The network node is pre-configured to receive RAT change notifications and automatically trigger appropriate codec changes. This preliminary setup enables optimal communication parameters during RAT transitions without adding complex real-time decision-making, balancing simplicity with productivity.
Solution Approach 2:
The patent implements feedback by creating a closed-loop system where RAT change notifications provide feedback to the network node, which then triggers appropriate codec changes. This feedback mechanism ensures that communication parameters remain optimal during RAT transitions without requiring complex predictive algorithms, achieving productivity improvement through simple reactive adaptation.
Data Source
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AI summary
A method of notifying one or more network nodes in a communications network, comprising an Internet Protocol Multimedia Subsystem, IMS, of a change in Radio Access Technology, RAT, used by a user equipment for a communications session, the method comprising at a Call Session Control Function, CSCF, prior to set-up of the communications session (30), indicating (31) by the CSCF to a Policy Charging and Rules Function, PCRF, that the CSCF requires RAT change notifications for the user equipment, providing (32) a capability indication by the CSCF to the one or more network nodes that the CSCF supports RAT change notifications and receiving (33) from at least one of the one or more network nodes a requirement indication, which indicates that the network node requires RAT change notifications. The method further comprises on receipt (34) of a RAT change notification by the CSCF propagating (35) the RAT change notification to each of the nodes from which a requirement indication has been received.