5G Call Flows (Session 2): 5G Intra-gNB & Inter-gNB Mobility Overview

[@OurTechPlanet]

For simplified 5G tutorial sessions, check out the complete playlist below :) 🌐5G Call Flows & KPIs 💡kzbin.info/aero/PL4OXTttOk9WhvApKwJBcZx0G4a2m8N-z6

[@harshsaxena9096]

This js the Kt video for me I was clueless from last 3 months and now getting the stuff…thank you sir 🙏🙏🙏🙏🙏

[@OurTechPlanet]

You are very welcome

[@rajbhupathi4190]

Crystal clear explanation of the concept with good screens including message contents. Thank you 😀

[@OurTechPlanet]

Thanks Raj :)

[@Worldpeacemaker99]

Simply Amazing. Your Videos and the method of teaching is super brilliant.

[@OurTechPlanet]

Thanks a lot, Satya!!! Made my day! :)

[@varun284]

Great kowledge...................kindly make video for 5G KPIs and counters

[@OurTechPlanet]

Will do so, stay tuned!

[@akmzakaria3054]

Absolutely Amazing !! Thank you so much for sharing the Beneficial knowledge !!

[@OurTechPlanet]

Glad it was helpful! :)

[@HK_CryptoEnthusiast]

Brilliant explanation. Keep up the great work 👌🏻

[@OurTechPlanet]

Thanks mate :)

[@charlesbulega9259]

Brilliant , super teaching

[@OurTechPlanet]

Glad you liked it.

[@laxmanmewari]

Very good session on Inter GNB HO..

[@OurTechPlanet]

Thanks!

[@m.karthikeyan6482]

Great session ❤️❤️❤️❤️❤️❤️,,, please post a session of SCG and SCG failure analysis in 5GNR

[@OurTechPlanet]

It is covered in the session-3 kzbin.info/www/bejne/eIrEaKWVYsaqkKc

[@indramani8888]

how about the UE ctxt release once UE attached to target gnb in inter gnb pscell change.? and sn status, end marker packet etc??

[@OurTechPlanet]

Would be good to refer to 3GPP 37.340 & 36.423 which have these call flows in detail

[@thirumalesancp989]

Awesome presentation! Many thanks for sharing...

[@OurTechPlanet]

Thanks! Good to hear that :)

[@iulhaq1]

Very well explained 👏

[@OurTechPlanet]

Thanks! :)

[@indramani8888]

can u share some insights on inter gnb mobility where anchor is also different . in this video the anchor was common for both of them. would appreciate if you can throw some light on that as well.

[@OurTechPlanet]

Sure, will add that soon!

[@rahul-vv1vh]

Inter-gnb PSCell change should be done through Event A5?

[@OurTechPlanet]

No, it actually depends if it is inter-frequency pscell change or not. If it is Inter-frequency PSCell Change then mostly A5 is used.

[@priyadarshini1130]

Thanks a lot, Very informative. I have a (question)request as I am trying to understand how the resources are managed within cells of same gNB. You have shown the spCellConfigCommon info for the second RRC Reconfig message. It will be helpful if you can share the same for the first one (where you just showed the measurement related info). This will clear how the resources are shared between two cells of the same gNB.

[@OurTechPlanet]

Ok, will work on it :)

[@muhammadaimanrazak6336]

In which message can we check the anchor is?

[@OurTechPlanet]

If you have RRC messaging, you can see the PCI in the RRC reconfiguration

[@fatimakhalid7446]

Explicitly explained

[@OurTechPlanet]

Thanks!

[@AIdreamer_AIdreamer]

Perfect videos. can you please explain a little about PRB and digitally beam forming and beam and null steering??. very much appreciated.

[@OurTechPlanet]

Sure, will work on it

[@georgioskarouzos7418]

Can a UE send A5 mesurement report for inter-frequency HO(NSA from n78 to n28)? Thank you

[@OurTechPlanet]

Yeah Inter-Freq NSA PSCell Changes are supported.

[@yap9660]

What is ENDC means?

[@OurTechPlanet]

ENDC = Eutran Nr Dual Connectivity The name comes from the fact that the handset/mobile is connected to both EUTRAN (4G) and NR (5G) at the same time - so Dual Connectivity

[@SunilKumarMidde]

Very nice explanation! one query, will LTE eNB know the target NR cell frequency(or band) , if yes what is the IE used in X2 message?

[@OurTechPlanet]

Yes, the LTE eNB will know the target NR Cell details as all control plane information flows through the LTE eNB and the LTE eNB is the one that will inform the UE to move the target NR Cell via RRC Reconfiguration. Now, how the LTE eNB gets this information, that is via SgNB Change Required message.

[@georgioskarouzos7418]

If SRB3 signaling is supported, A3,A5 Measurement reports can be sent directly from Ue to gNB for PSCell change decisions. Is it correct?

[@OurTechPlanet]

Yes, correct.

[@mustafacoskun5803]

Thank you for simplified explanation. In inter gNB HO, shouldn't the eNB HO also occur. You explained such that only gNB is changing, how will new gNB communicate with EPC through the old eNB because most probably after the HO, old eNB coverage will be very bad.

[@OurTechPlanet]

eNB to eNB mobility will be based on LTE handover events. It is possible that gNB is using a higher frequency which has lower coverage while eNB anchor is using a low frequency band with much higher coverage such that the eNB anchor also covers the second gNB as well

[@mustafacoskun5803]

@@OurTechPlanet Yes, you are right, that is possible. I haven't thought about that. Thanks..

[@vinoddubey7057]

In case of Inter SgNB HO, UE will move to the target SgNB and data transfer start. What about the Anchor node(if target SgNB is 5KM away and moving towards SgNB), Anchor LTE node will be the same or its also going to be change with the target SgNB

[@OurTechPlanet]

Anchor does not need to be changed in inter-sgNb HO as long as a valid X2 link exists between the anchor and the new gNB. If the target gNB is at a distance which is greater than cell radius of that gNB then the UE will fail at RACH.

[@adeelkhanpersonal]

Very well explained. Just 1 query. If during A3, the difference of RSRP between 2 gnodeb is just 1 dB, will it still attempt to handover because its just 1 dB better ? Or there is any parameter which restricts it to have minimum difference of levels between 2 gnodeB?

[@OurTechPlanet]

The A3 offset + hysteresis are the relevant parameters. For example, If A3+Hyst is 4dB then the handover will only happen when the target is better than the source by 4dB or more!

[@friend4udear]

Thank you Very informative. In case of HO from LTE cell A NR cell A to LTE cell B NR cell A, i.e, NR cell remain stationary, how does the LTE cell B get NR cell A info. What will be the additional messaging?

[@friend4udear]

I mean without release and add. With Only Sgnb addition option.

[@OurTechPlanet]

Sorry, somehow, I missed your comment. There are generally two implementations for this. One releases the NR cell and then re-adds it at the target cell. The second implementation retains the NR Cell. This is done by adding the NR Cell Configuration in the LTE Handover Request message from CellA to CellB

[@friend4udear]

@@OurTechPlanet Thankyou!

[@shubhamshrivastava603]

Nice Explanation

[@OurTechPlanet]

Thanks Shubham!

[@MohamedAdel-op2ug]

Very well done thanks brother, one question, what if the eNB also need to be changed so that the UE triggers A3 for LTE leg and 5G leg? "Let's say both have similar coverage e.g. NR700 + LTE800. Thanks

[@OurTechPlanet]

The process which starts first should be completed first. However, this should be implementation specific but I would say that LTE HO should be prioritized as LTE carries the control plane.

[@naturelearning8416]

Ur explanation is so simple so very easy to understand. I want to do online courses on 5G call flow and KPI in detail. Can u arrange for it.

[@OurTechPlanet]

Not at the moment but will definitely let you know if we plan them in future. Thanks for liking the videos :)

[@naturelearning8416]

@@OurTechPlanet thanks for your kind reply. plz let me know once you plan for such courses online.

[@HarpreetGujral27]

Content is very beautifully narrated, Thanks for such videos. One query , Will Endc attempt pegged here also when Menb requested gnb addition during inter pscell HO ?

[@OurTechPlanet]

Thanks This depends on the vendor implementation of the counter pegging mechanism.

[@akshayakumarsingh7080]

love to listen more videos

[@OurTechPlanet]

Next video for the 5G Call Flow series is also published :) kzbin.info/www/bejne/eIrEaKWVYsaqkKc

[@ZDToxicGaming-qf6jl]

Great Content 👍👏👏

[@OurTechPlanet]

Thank you.

[@raminsabzalizade4629]

Hi, in our nsa network the enb type ericsson and gnb huawei, the scg addition success rate is 70%. As x2 signaling checked, it shows that gnb after sending the ack for scg addition, it sends the scg release with mcg failure , what do you guess about this issue ?

[@OurTechPlanet]

Inter-vendor compatibility and inter-operability issues usually cause this. Would be difficult to find the rootcause without system level traces from both vendors.

[@shatriyan123]

Will UE lose 5g coverage during handover to another Anchor LTE site if UE still continues at 5G gNB-2 Cell-3? Pls explain. Thanks

[@OurTechPlanet]

This depends on vendor's implementation. Both scenarios are possible, LTE to LTE HO can cause release of 5G resources and then re-add on the new LTE anchor cell after handover. The other scenario is that NR config is passed to the target LTE cell and in that case, it is more seamless and NR service is carried over to the target LTE Cell during LTE to LTE HO. I will do a detailed session on that too later!

[@shatriyan123]

@@OurTechPlanet Thank You, looking forward to seeing that session.!!!

[@bushysaba]

جزاك الله خيرا

[@OurTechPlanet]

Thanks :)

[@georgioskarouzos7418]

In case of inter-gnb pscell change, the Sgnb addition is not triggered by new B1 measurements but by the A3 or A5 measurement report.Is it correct? No new B1 measurements are needed for the target gNB.Is it correct?Thank you

[@OurTechPlanet]

yes, that is correct.

[@coolmunzir]

SgNb Reconfiguration Complete will only send by eNb in case of Inter gNb Handover?

[@OurTechPlanet]

Yeah that message is part of SgNB Addition procedure so it only comes into picture during Inter-gNB HO as the eNB adds the new gNB in that process.

[@shaiksoofi3741]

Awesome 👌

[@OurTechPlanet]

Thanks 🤗

[@saxenarohit59]

Why we have to delete 156 from RSRP?

[@OurTechPlanet]

It is just the working as per 3GPP. In LTE, we used to subtract 140 and in 5G, we subtract 156. This helps in sending non-negative values in measurement reports.

[@saxenarohit59]

@@OurTechPlanet thanks, its very clear now

[@saxenarohit59]

@@OurTechPlanet this means negative values are not supported or they occupy more bits so message becomes longer. Please explain sir.

[@OurTechPlanet]

@@saxenarohit59 yes negative values are not supported. Your understanding is correct.

[@giacomocroce5905]

So Good presentation

[@OurTechPlanet]

Thanks :)

[@Manlikejj.__]

Share it

[@OurTechPlanet]

Thanks, please do :)

[@fvbeek9132]

good presentation only there is a mistake it think correct me if i wrong the last handover is a inter-gnb it should be A2- A5 not A3 kzbin.info/www/bejne/pIuuf2mIZ7SafLM

[@OurTechPlanet]

No, A2 and A5 are used for Inter-Frequency Handovers. Over here, we are talking about Intra-Frequency handover. Note that Inter-gNB handover can be Intra-Freq or Inter-Freq.

[@augustusjulius5892]

Nice Explanation

[@OurTechPlanet]

Thanks, Augustus.