IMS Redirecting WPS Media Sessions to LTE
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Solution Overview
Problem
Current interactions between Wireless Priority Service (WPS) approved User Equipment (UE) and Internet Protocol Multimedia Subsystem (IMS) systems are ineffective in redirecting media session invites with a WPS prefix from untrusted networks to Long Term Evolution (LTE) networks.
Innovation Solution
The IMS identifies the WPS prefix in a media session invite, adds a Resource Priority Header (RPH), authenticates the UE, and instructs the UE to re-originate the media session invite over the LTE network, ensuring priority treatment and secure communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a media session invite with WPS prefix is transferred over an untrusted network (WiFi) to the IMS system, then the call can be established, but the priority service cannot be properly initiated and the network trustworthiness is compromised
Solution Approach 1:
The IMS system acts as an intermediary that receives the media session invite from the untrusted WiFi network, performs authentication and validation, then redirects the session to the trusted LTE network. This mediator approach allows the system to initially accept connections from untrusted networks while ensuring that priority services are ultimately established over trusted networks through the redirect mechanism
Solution Approach 2:
The system performs preliminary authentication and network type detection before allowing the media session to proceed. By checking the network type and authenticating the UE in advance, the system can determine whether to allow direct connection or redirect to LTE, preventing priority service initiation issues before they occur
2Reliability
If the IMS system implements redirect logic for WPS calls from non-LTE networks, then priority services can be ensured over LTE, but the interaction complexity between UE and IMS increases
Solution Approach 1:
The IMS system provides feedback to the UE about the detected network type and the authentication result. Based on this feedback, the UE understands whether it should re-originate the session over LTE. This feedback mechanism streamlines the interaction by providing clear directional guidance rather than requiring complex UE-side decision-making
Solution Approach 2:
The UE is empowered to self-determine the appropriate network based on IMS instructions. The UE autonomously decides whether to re-originate the session over LTE based on the redirect indication from the IMS, reducing the need for complex centralized control while ensuring proper network selection
Data Source
AI summary
An Internet Protocol Multimedia Subsystem (IMS) receives a media session invite having a Wireless Priority Service (WPS) prefix over a non-Long Term Evolution (LTE) network for a User Equipment (UE). The IMS identifies the WPS prefix and adds a Resource Priority Header (RPH) indicating that the media session invite is for a WPS call. The IMS transfers an authentication request to a WPS Application Server to authenticate the UE for the WPS call based on a UE identifier and receives an authentication response indicating that the UE is authenticated. The IMS determines that the media session invite was transferred over the non-LTE network and transfers an instruction to the UE indicating that the UE should re-originate the media session invite over the LTE network. The UE receives the instruction and transfers the media session invite having the WPS prefix to the IMS over the LTE network.