How UE determines Target Cell PCI during Handover? Where can we verify that UE latched to configured Target PCI ?

Question

Please explain in detail "When and where data buffer will start during x2 and s1 handover and when it will forward to target cell"

Answer 1

UE sends measurement report(s) to eNodeB, based on the report(s) , eNodeB initiates either X2 or S1 based handover procedure. MobilityControlInfo within the RRC connection reconfiguration carries target physical cell Id.

Soon after this message, UE starts searching target cell based on PSS and SSS since both are used to identity physical cell Id. Once RRC connection reconfiguration complete message is received by eNodeB , handover procedure is considered successful. There are so many places like UE logs, target eNodeB logs from where can be figured out, UE is handed over to target cell successfully. Wireshark logs will also show change in "IP address" for GTP packets between eNodeB and SGW since eNodeB has been changed for an UE.

Now and days, few applications are there which can be used to get network information like current cell, tracking area code , plmn etc.

Answer 2

As Vimal suggested, check RRC reconfiguration message which will have target cell information

If you have samsung UE, you can check which PCI UE is latched to using this code *#0011#
This will display serving cell information

For any other android UEs, you can install G-NET TRACK app to check cell level information

QXDM logs, wireshark logs wil also carry information you are looking for