5G: Which network node will be supporting buffering of incoming downlink data when UE is in CM-IDLE state ?

Question

In LTE network, when an UE moves to ECM-IDLE state, SGW buffers the incoming downlink data and notifies to MME. Afterwards, MME initiates paging procedure for the UE. I want to know that how 5G is going to handle same scenario ?

Answer 1

Though I am new to 5G network but based on my previous learning of LTE and study of 5G, I came to know that paging will be supported in 5G network as it is supported in LTE network. In 5G network, Session Management Function (SMF) and User Plane Function (UPF) both are responsible for data path. Once UE moves to CM-IDLE state, UPF can't forward the incoming downlink data.
In this case, either SMF or UPF supports buffering of downlink data, location of buffering is decided by SMF.
If buffering occurs at SMF, then it relays all the buffered data to UPF once UE moves to CM-CONNECTED state so that UPF forwards the same buffered data to NG-RAN and thereafter it continues to forward the incoming data to NG-RAN as usual it does.