Why 5G ANR is not working when SIB1 is disabled in the 5G NSA Network?

The explanation for why 5G ANR is not working when SIB1 is disabled in the 5G NSA Network.

This article explains why 5G ANR is not triggered and does not work whenever SIB1 is disabled in the 5G Non-Standalone network.

Read article: :point_down:

Hi @Mohamedeladawi, thanks for sharing.

I have a question: did you mean 5G site will encapsulate SIB1 in RRC-reconfig fail to UE that already reported missed PCI from old MRs?

You are welcome.

No what I meant that the target 5 (Cell/site) will broadcast SIB1 information to all UE, accordingly the UE will read SIB1 (system information) from target cell to obtain CGI-Info.

As you know that In NSA networking, SIB1 transmissions are optional.

Then to ensure that missing neighboring cells can be automatically detected and added, all cells needs to send SIB1 so that the UE obtains CGI-Info.

I tried to simulate the scenario many times from the field to compare SIB1 infor between 5G sa and nsa but i couldnt get SIB1 for 5G NSA from the field.

Exactly what i was thinking, so i think No ANR in 5G and you have to define 5G-nbrs manually.

Other vendor like as Nokia have feature that can map reported NSA_PCI for 5G nbrs to CGI via automatic X2 setup procedure between Menb and Sgnb.

No dear, 5G NR do exist and it is working on all vendors.

I do enabled in and checked other vendors report as well, and in the beginning it was not triggered but once SIB1 enabled it take effect after.

So how UE that have signaling only via lte can read SIB1 tha 5G-NR broadcasting?

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Good question!

I will search and get the answer for you later.

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No My friend. 5G ANR in NSA architecture works smoothly if NR SIB1 transmission is enabled on gnodeB. NR system information is broadcasted on PDSCH. In NSA mode UE does not have RRC layer with 5G. It does not mean it can not decode NR system information shared on 5G PDSCH channel. UE can read all 5G logical channels including PDSCH, PDCCH etc.

LTE-NR ANR via X2 interface you just mentioned is also available in Huawei RAN as well but it is something different with event based ANR explained above. In ANR over X2 interface gnodeB will give external neighbor information to master enodeB upon receiving X2 setup request message and Enb will add neighbors without the need to read NR SIB1. In other scenario of this option after X2 setup between LTE and NR if any configuration changes happen on NR side (such as PCI or gnodeB ID modification etc.) gnodeB will automatically ask peer enodeBs to update external neighbor relations on their side.

It first read MIB and there is pdcchconfigSIB1 and then it knows where and how to look and decoded SIB1 NR.

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It requires core network support as well via 3GPP 36.413 CR#1662 (attached)

UE can decode sib1 only when it requires CGI reporting, in other situation you will not measure it on field in NSA.

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And also require UE capability support, as I remember.

What is ANR switch parameter name in Huawei?

Intra or inter?

5G NSA Addition ANR switch.

  • 5G->5G
    NR_NR_ANR_SW (MO NRCellAlgoswitch.AnrSwitch)

  • 4G->5G
    You need to turn on (LTE side)

You can also turn on NSA_Cell_Sib1_SW

Sib 3 will work on NSA.