Hi NR Experts.
How network indicates to UE that cell is ENDC or non ENDC?
Any message there?
How UE will come to know if we have both LTE and ENDC cell in cluster?
Not an expert but, in SIB2 msg UPPERLAYERIND, if this is ON, UE will know that LTE cell has an upper NR layer.
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LTE SIB2 → PLMN information list → If upper layer IND IE is set a true, then network support ENDC.
Everyone here are Expert 
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Of course, upper layer indication isn’t mandatory and without it UE can connect to NR.
Yes, UE can connect with without upper layer indication.
If this indicator is enabled then UE get to know that network is supporting ENDC.
Using that indication UE can display operator specific icon. Example: 5G, 5GUW.
In my view, SIB2 is only for icon display, not to judge cell is ENDC or not.
Is SIB 2 always broadcasted? I think SSB + SIB1 i.e. minimum system information are always broadcasted.
I read somewhere: if NR SIB1 carries TAC information, it is SA. If NR SIB-1 doesnot carry TAC info, it is NSA.
In the case of LTE SIB2 always broadcast.
In the case of NSA, SIB1 is not required only MIB required.
In the case of SA, MiB and SIB1 is always broadcast, and other SIBs broadcast base on operator requirement.
SIB2 always broadcast, but upper layer indication not mandatory.
SIB2 upper layer indication decides cell is EN DC or not.
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As far as I have seen, all documents state 1 thing: that SIB2 Carry 5G NR PLMNs via PLMN info, which tells UE the presence of NR in the network along with LTE.
That’s the trigger point after which UE sends DCNR to n/w on msg3
Presence of New SIBs indicates whether NW is ENDC or not.
ENDC (E-UTRA-NR Dual Connectivity) is a feature in 4G and 5G networks that enables simultaneous connection to both 4G and 5G networks. This allows for a smooth transition from 4G to 5G networks, ensuring uninterrupted connectivity and improved user experience.
In NSA (Non-Standalone) mode, ENDC enables a device to connect to both 4G and 5G networks simultaneously, with the 5G network providing additional capacity and improved performance.
In SA (Standalone) mode, ENDC allows for seamless handover between 4G and 5G networks, ensuring uninterrupted connectivity.
Here are some test cases and examples for ENDC in 4G and 5G networks:
Test case 1: 4G-5G handover in NSA mode
A device is connected to a 4G network and 5G network simultaneously through ENDC.
When the device moves out of the 4G coverage area and enters the 5G coverage area, the device automatically switches to the 5G network without any interruption in connectivity.
Test case 2: 5G-4G handover in NSA mode
A device is connected to a 5G network and 4G network simultaneously through ENDC.
When the device moves out of the 5G coverage area and enters the 4G coverage area, the device automatically switches to the 4G network without any interruption in connectivity.
Test case 3: Seamless handover in SA mode
A device is connected to a 4G network and 5G network simultaneously through ENDC in SA mode.
When the device moves from a 4G coverage area to a 5G coverage area, the device automatically switches to the 5G network without any interruption in connectivity.
Similarly, when the device moves from a 5G coverage area to a 4G coverage area, the device automatically switches to the 4G network without any interruption in connectivity.
Example:
Let’s say you are using a 5G-enabled smartphone and are browsing the internet on a 5G network. As you move out of the 5G coverage area and enter a 4G coverage area, your smartphone automatically switches to the 4G network without any interruption in your internet browsing session. This is possible through ENDC, which enables simultaneous connection to both 4G and 5G networks, ensuring uninterrupted connectivity and a seamless transition between the two networks.
Credits: 
Hi experts,
How UE indicates that the network cell support or not support ENDC when PLMN-Info list doesn’t exist in SIB2 message?
And what if it is not contained in SIB2 message at all ?
How can the UE know