My friend: Hi Ibrahim, I have a question for you.
Me: Please, go ahead.
My friend: I saw this paper where you wrote some things related to 5G and it was mentioned NEDC which I think is a typo mistake and you mean ENDC, right?
Me (smiling): Thanks for your notice, but actually I meant NEDC.
My friend: Really, so what is NEDC in 5G?
Me: It is very simple as ENDC is an abbreviation for E-UTRA-NR Dual Connectivity, also NEDC is an abbreviation for NR-E-UTRA Dual Connectivity and both are two types for dual connectivity where UE is connected to two BTSs at the same time, but for ENDC, the master node (MN) is 4G BTS and the secondary node (SN) is 5G BTS, that’s why E-UTRA was mentioned first and NR was mentioned second in the abbreviation ENDC as first letter is used for MN and second letter is used for SN. While for NEDC, UE is connected to one 5G BTS that acts as a MN and one 4G BTS that acts as a SN. Also, take care that for ENDC, both BTSs are connected to EPC while for NEDC, BTSs are connected to 5G core as per 3GPP 37.340.
My friend: It is clear now. Thanks a lot.
Me: You are welcomed.
Source: Ibrahim Sayed
Linkedin Profile: https://www.linkedin.com/in/ibrahim-sayed-88a7747-5g/