Dynamic I1-ps Connection for IMS Services
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Solution Overview
Problem
Current IMS centralized services face limitations in providing mid-call services during circuit-switched calls, particularly with I1-ps, due to bandwidth constraints and the need for EDGE or UTRAN features, and the requirement to initiate SIP sessions at the beginning of every CS call, which restricts the availability and functionality of supplementary services.
Innovation Solution
A network control node capable of performing circuit-switched sessions and sending/receiving session control messages, which receives specific session control messages from user equipment to establish a packet-switched connection dynamically, allowing for the provision of services during circuit-switched sessions by encoding information in a suitable format and binding the packet-switched connection with the circuit-switched session using a session identifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If I1-ps connection is formed at the time a CS voice call is established, then service consistency between CS and PS accesses is ensured, but unnecessary connections and signaling are created when the connection will not be needed during the call
Solution Approach 1:
The patent applies preliminary action by preparing the I1-ps connection in advance during call setup, but making it optional and conditional. The network can pre-establish the packet-switched connection infrastructure while allowing the call to proceed on circuit-switched resources, enabling quick transition to IMS services if needed without forcing the connection establishment
Solution Approach 2:
The patent implements dynamics by making the I1-ps connection establishment flexible and adaptive rather than mandatory. The system can dynamically decide whether to form the packet-switched connection based on service requirements, user equipment capabilities, and network conditions, allowing the connection state to change during the call lifecycle
2Adaptability or versatility
If I1-ps is used to provide mid-call services during CS calls, then service availability is improved, but bandwidth constraints and requirement for EDGE or UTRAN features limit its applicability
Solution Approach 1:
The patent applies universality by designing the I1-ps mechanism to work across multiple access types and service scenarios. The same packet-switched connection framework can support various IMS services (conferencing, call transfer, call hold) regardless of whether the underlying access is 2G, 2.5G, 3G, or LTE, making the solution universally applicable without requiring access-specific implementations
Solution Approach 2:
The patent uses the I1-ps connection as an intermediary layer between the circuit-switched voice call and IMS services. This intermediary packet-switched channel carries signaling and data for supplementary services without interfering with the primary CS voice bearer, allowing services to be added dynamically while maintaining compatibility with existing CS infrastructure and avoiding direct dependence on specific radio access features
3Ease of operation
If SIP session is initiated for every CS call, then service control capability is ensured, but the complexity increases and services are unavailable if initiated in the middle of CS call setup
Solution Approach 1:
The patent applies segmentation by separating the voice call establishment (circuit-switched) from the service control signaling (packet-switched I1-ps). This allows the voice call to be set up independently and quickly on CS resources, while the I1-ps connection can be established separately and independently to carry service control signaling, enabling services to be added at any stage without blocking the primary call setup
Solution Approach 2:
The I1-ps connection serves as an intermediary signaling channel that mediates between the CS call control and IMS services. It allows service control messages to be exchanged independently of the CS call setup progress, enabling services to be initiated and controlled during the call without adding complexity to the core CS call control mechanism
Data Source
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Figure 3A~3B
AI summary
A device is described which comprises a sender and a receiver configured to perform a circuit switched session, wherein the sender and the receiver are capable to also send and receive session control messages according to a session control protocol, and a controller configured to receive a specific session control message, wherein the session control message includes information for establishing a specific packet switched connection capable of supporting a specific packet services to a network node, wherein the information is encoded in a format suitable for the session control protocol, wherein the controller is further configured to obtain the information from the specific session control message, and to establish the specific packet switching connection based on the obtained information.