ePDG Gateway Selection for VoWiFi Latency
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Solution Overview
Problem
Existing VoWiFi and ViWiFi call systems face challenges in selecting the appropriate network gateway for seamless hand-offs between WiFi and cellular networks, often resulting in inefficient routing due to the lack of knowledge about the user equipment's location by the evolved packet data gateway.
Innovation Solution
A solution that involves determining the geographical location of the user equipment based on its IP address, identifying a tracking area code, and subsequently selecting a network gateway with user plane and session management functions to establish a voice traffic session, ensuring proximity and continuity during hand-offs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ePDG assigns the network gateway randomly when VoWiFi/ViWiFi call is initiated, then the call can be established, but the gateway may not be proximate to the UE causing increased latency and potential hand-off issues
Solution Approach 1:
The ePDG performs preliminary location determination using the UE's IP address before gateway assignment. By determining the geographic location and tracking area code in advance, the system pre-identifies the most appropriate network gateway, ensuring both low latency and session continuity without waiting for hand-off events
Solution Approach 2:
The system uses the UE's IP address as feedback to determine geographic location, which then feeds back into the gateway selection process. This closed-loop approach ensures the selected gateway is consistently proximate to the UE's actual location, improving both establishment speed and hand-off reliability
2Reliability
If the ePDG uses location-based gateway selection, then the gateway is proximate to the UE improving hand-off reliability, but the ePDG must perform additional location determination operations increasing system complexity
Solution Approach 1:
The ePDG performs multiple functions using the same IP address data: it determines geographic location, identifies tracking area code, and selects the appropriate network gateway. This multi-functionality approach consolidates what could be separate complex processes into a unified gateway selection mechanism, reducing overall system complexity while maintaining high hand-off reliability
Data Source
AI summary
Selecting local gateways for VoWiFi and/or ViWiFi calls (voice traffic sessions) for a user equipment (UE) includes: receiving, by an evolved packet data gateway (ePDG), a request to initiate the voice traffic session from a WiFi router outside a cellular network that is communicatively coupled with the UE; based on at least an internet protocol (IP) address of the WiFi router or the UE, determining a geographical location of the UE; based on at least the geographical location of the UE, determining a tracking area code; based on at least the tracking area code, determining an IP address of a network gateway proximate to the UE, wherein the network gateway comprises a user plane function (UPF) and a session management function (SMF) or a packet data gateway (PGW) user plane function (PGW-U) and a PGW control plane function (PGW-C); and establishing the voice traffic session using the network gateway.