RACH in NR call flow

5G NR
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42

Let me show KPIs from my network and show you how when RACH fails ENDC drops increase:

5G NR ENDC drops
5G NR ENDC drops1280Ɨ720 48.4 KB

Number of ENDC drops correlating with RACH failures
Number of ENDC drops correlating with RACH failures1280Ɨ720 75.1 KB

Number of ENDC drops correlating with RACH failures!

43

If understand you quey well: Such case where post B1 measurement when MN tries to establish SN as SCG addition or NR cell addition.

There could various failures

And then SCG failure will be called.

44

Yes, perfect.

45

But will be called as SgNB addition failure and pegged in 5G drop as per counters.

46

RACH comes after ENDC and no preambles canā€™t exceed RACH preambles transmax (configured 10) per ENDC sucess wich is in my case much more than 10.

Due to DTX.

Please check RACH preambles msg-3 sucess which is NR RACH NSA degradation, even though your ENDC is good.

47

In NSA, RACH failure has nothing to do with ENDC Setup success rate.

RACH failure comes into picture when calculating Drop.

48

As per as I know, the RACH comes before ENDC setup.

49

That is for LTE ā€œattach request".

Thatā€™s what we are saying ENDC setup SR does not count RACH failure in case of NR addition or SCG addition or NR leg addition or SN addition.

As far as I know, all 3 vendor use same philosophy as per 3GPP standard.

50

That means in 5G NSA, the 5G RACH procedure occurs after ENDC setup?

52

Yes, correct.

53

Yes, there will 2 different RACH setup procedures one at LTE attach request initial attach request.

And then after ENDC setup completion then UE will do NR leg addition.

54

Sorry, I donā€™t agreeā€¦

55

Ok dear.

Then I am sorry, You are rightā€¦. And I am Wrong :blush::pray:

56

Thank you for your feedback dear, it is truly appreciated.

However, Iā€™d like to clarify that we are discussing the merging of NR RACH KPIs and ENDC KPIs. While I understand that NR RACH is mandatory for ENDC setup to succeed, in my case, the ENDC KPIs are good, but the NRDU KPIs are not.

Experts, I kindly request comments specifically on this context.

57

I got your point and to answer your question you need to check formula of your EnDC sr and SCG or SgNB sr.

You will get your answers automatically

Thanks :pray:

58

Hi, what is the sum of counter formula here?

59

ENDC drops is ENDC abnormal release.

The other counter is a counter it self, not a formula

The vendor is Samsung by the wayā€¦

60

Big thank you to all the experts, for the insights, and patienceā€¦

But as I still have doubts, i still search for someone to clarify:

  • In NSA, we have the ENDC process, which you may be familiar with.

  • After the UE completes RACH with the gNodeB, the ENDC is successfully established.

  • However, if the UE fails the NR RACH with the gNodeB, the ENDC will also fail.

  • My question is straightforward: in my network, the ENDC KPI seems fine, but the NR success rate is significantly low.

    • Could you provide your insights on this issue?
61

Hi I got your point in your case ENDC is established but this Ue measures neighbor NR cell and trying to change the and leg we call pscell change , here it has to undergo the rach process again where as your Menb remains same . During this rach process if you see scg fails there are 2 possibilities either NR pci conflict or the neighbor cell is too far and UL coverage is too bad so that gnb canā€™t rcv the Ue message. Correct me if am wrong, thanks ā€¦