How LTE coexistence with WIFI works and How UE latches with Wifi ?

Question

During the Handover from LTE to WiFi, how an UE is authenticated at WiFi network ?
Is there any difference in authentication procedure when UE is handed over to un-trusted or trusted WiFi network ?

Answer 1

I don't have complete information on inter-working of LTE and Wi-Fi but get to know few basic concepts which I would like to share here. There is a network node known as "ANDSF (Access Network Discovery Support Function) " plays a major role/primary role on selection of relevant Wi-Fi network.
When UE is connected to LTE network and if it sees good signal strength of available WiFi access networks, it contacts to ANDSF to get the relevant Wi-Fi network details and initiate connection towards Wi-Fi network.
While establishing connection with Wi-Fi, UE IP address is still same as allocated by PGW since ePDG of Wi-Fi network gateway makes connection to the same PGW and the data flow is continued.
This is what I learned from different online material but still does not have concrete knowledge on that.

Comments

Could you please explain what information ANDSF maintain for Wi-Fi network ? Does the ANDSF expect any special information from the UE for the selection of Wi-Fi access point ? and one more basic question, how UE get the ANDSF node address ? Is it already configured in UE or Network provides this address similar to P-CSCF ?