Session 3: 5G NSA Mobility: E2E Call Flows & Troubleshooting

hello everyone welcome to the third session of 5G non stand alone Mobility actually in this video we will break down into the essential understanding of 5G non non mobility and we'll try to explore or exploring all the end to end cold flow for related to the mobility using traces and logs and also we'll try to highlight the most common issues and problems you you might face while doing any trouble shoting for the 5G Mobility nonstandard mobility and also we'll try to address the most common parameters related to the tuning or for the layering of the

mobility in general and the types of handovers or the mobility we we have it non stand just a quick a quick comment comment or a a reminder that if you remember that I would like to highlight that this actually series of Five series will try to cover all the related aspects in term of practical or theoretical knowledge of 5G non standard including features traffic management through trouble shoting and also frame structure and and anchoring and all these kind of things we'll try to cover it in on all the series in in case to have a

complete at the end you can have a complete course about 5G stand alone which can which can help you like even to move from beginner level into a very advanced level so please make sure to subscribe to the channel and to spr the knowledge so let's move forward actually this will be the contents of today that first we recap quickly the architecture Network option 3x and the mobility overview what kind of Mobility types we have it understand alone then we'll move into how to check the NDC or user EU capability message for to confirm whether

this particular user is supporting for example inter or intra frequency handovers for n stand alone then we'll go through the ENT call Flow using traces then we I will be ending by the most common handware failures and related parameters which is like very common and I think you'll be already aware of it so let's move forward so actually if you remember this figure already presented in accessibility slides this is just like recalling for op option 3x but main take away here from this slide which I would like again to recap it this kind of distribution

of the cells as you can see here in the left this is a master node or this is a 4G which is the anchoring layer and we have here the 5G which is J B secondary Jun B and this is a master node B and here is the and here is we have the ABC which is can be serving gway and M both combined so we have four cells as you can see here two cells cell one and three is for 4G and cell two and cell four is for five just just keep it in

your mind always cell one this is a primary this we call it the primary cell as you can see here this is a primary cell and cell two for secondary n this is the primary secondary cell so usually in in most of the networks you'll find you have multiple carriers maybe in 4G and only one carriers not most of but Depend and one carriers for example in in the in the in the 5G so in case of car aggregation you will have this cell three and cell four and this is always called as a secondary

set so whenever for example you are looking in the traes and you're trying to find the configuration for the the primary cell of the serving s genb this would be always called SP cell secondary primary cell so just keep this kind of definition or concept especially for the cells into your mind because this will be very important so regardless the Handover types we'll cover the next slides in details so moving forward now as you can see here in the in the left figure here this just highlighting what kinds of Mobility we have it and non

stand alone currently actually the most common or most one that initially in any network in the initial phase for any network for non stand alone as you can see you have three types here the one which the most most Comm one is just the handovers we don't have idle mode we don't have idle mod because still our anchoring in 4G so the idle mode Mobility will be through the 4G but if you're speaking about 5G stand alone we have theg B cell change or Handover the secondary primary L which is or which is related mainly

to the 5G nude and this can be intra INB or in INB and also can be intra frequency or inter frequency depending on how many frequencies we have in in the current 5G so this is one of the most common types which we are going to explore today in today so this is using usually event A3 or o5 as mentioned A3 and A5 A3 usually for inter frequency hand over and A5 usually for inter frequency hand over and the second type we can call it Mobility as well is secondary sell change this is in case

if you have multiple carrier and or three carriers for example and you have car aggregation in 5G and there is a change of the secondary cell which we highlighted the concept in previous slide so in this case ASX trigger can be used and this is yeah this is usually actually not only for the inter frequency this is usually used for intra frequency when you change it from example from one side to another and you would like to change your second b or even within the same sites inra intra be if you have one cell secondary

cell is better than yours so this will be changing using this event A6 then the last one which is actually whenever you have start having mixed Network deployment between un understand alone in this case there is a redirection or Handover can be enabled from 5G non Standalone to SAA to Standalone this is for the 5G Standalone capable devices who Who coming non stand alone he can move back through redirection or even Handover and this is using B1 event so these two will be explored in in different sessions like one related to car aggregation feature in

general and the other one whenever we go to the stand alone will be covering this one actually in more detail so today we'll be covering that part which is related to the be change or secondary primary cell change in general so if you look into the figure on the right this is the master noes which is related to 4G the first one in the left and one on the right this is two different sides and we have two sides for the 5G as well which is called secondary reg gen B1 and second B2 so initially

once the user move from left to right first thing he will do he will just add the secondary cell of this part once he act move into the coverage of this particular cell he will just be adding the second region would be then in in between here he might do some like for example assuming that this is anchoring already coming in this master node he might change from this cell for example to this cell so this is will be like a secondary cell change this is used using it's called usually it's j modification like whenever

the J having inter frequency and over it's required to modify the the configuration or even the cell through sending something called This Be modification and this will be explored in the signaling part so this would be the scenario for example assuming this master B and you have cell a from this particular site and user moving from here to cellb for example so in this case the S modification request will being sent from the SB to the master NB asking asking him that I would like to change from cell a to cell b my configuration from

cell a to cell b and this is also can can be sa concept like we're going to address now for the even inter Jun be not only intra Jun B hand over so and and here okay moving forward now Master be this is same concept actually the important point I would like to address that we have two types of handovers in general in 5G which is intra or inter unity and classified into intra intra and Inter frequency but still there is another factors which can be triggered the the handovers which you need also to be

aware of it for example if you have anchoring change we have one cell change it in the master B from cell a to cellb or there is a Handover in General within the 4G itself so this is can trigger Handover so just one point this means if you have for example some issues on mobility of the 4G Standalone network will be back impacting the 5G because every time you're doing 4G Handover you would like to also change or release or add your 5G leg as well so that's why I'm highlighting here Master be Handover for

example I have here assuming that I'm moving from for example Master B1 cell a to cell b so in this case I might do a change but in all cases I need to release and add it again or this one I need to request to add the secondary Noe so in this case assume that the is still within the same B is cell change no change but sometimes you need to change it if if you move to another cell as well but in general this will be disturbing the 5G because still once you move from

here to there this will be releasing and adding again the new secondary cell and also this will be quickly explo explore today so this is also one of the things that can trigger which is usually called MN initiated which means the Handover be initiated by the master no then here this is one of the most common as well now we start moving in was a coverage between the red one and blue one which is s b and B1 and two so here this is now inter inter gen be inter be hand over and this is

also require a secondary C change and this is for example assuming here as one as this one you in this site and you're moving now from cell a of this particular cell to cell cell b for example from this particular side so in this case this is will trigger something called Deion be Handover and again this is must be Handover this is in case you completely changing the side and once you move out of the 5G coverage will be releasing the car so this just a quick recap or overview that just the the K or

the summary of this slide that yes the Handover will be mainly types of inter intern view of the 5G but still it's can be triggered as well through the 4G whenever the 4G having an Handover so this means that you would like to you have to take care of the strategy of for both 4G and 5G because then this is very important for for like keep the 5G or increasing the 5G traffic so let's now let's move to the signaling details so before quickly moving before moving to the U capability I would like to the

5G Cod flow I would like first to take you for this one point which is usually being supported but in in case if you would like to check the U capability we need to to go into this message which is called UNR capability andr check and under that you would like to search for this measurement and Mobility parameters and here you will find one one parameter code which is 3gb defined by 3bb in and enter F measurement and report this is just indicating whether the user is supporting both in and Inter frequency measurement or not

so this is if it's not supportive for example this means you will you might have no no Handover being triggered by this particular user in case of measurement phase so this is just for your information and here is the reference for that one so now let's move to the end end to end C flow and see what we have okay so initially I would like first to start with this part which is related to to primary secondary C change and here I'm highlighting for inter unit B or s b whenever you're moving for have two

different sides for the 5G and I would like to highlight so first let me quickly explain this one then we'll open message by message to see what we have within this message and how can we like do the trouble shoting for the Handover whenever we are opening our Tres so as you can see in this figure here initially the endc or theb addition is being completed here and within this complet of the NC setup orgb addition that there is some configuration related to the Handover in general being delivered in our RSU configuration message related to

A3 and A5 events which is intra or inter frequency depending your network for sure if you don't have inter frequency so it will be only A3 so this configuration already delivered within within the RSU configuration which was being used during the configuration of the primary cell during the Eng be addition so once the user received this kind of configuration for ENT frequency he will keep measuring so in case in case for example already the event being triggered achieved for the 3old which is being sent within this kind of message and they will show it you

after maybe we finish the high level introduction then the user will be sending M report like asking the master node that okay I achieve the A3 A3 sh for example three sh so I would like now to do one hand over so the master note will St forward to the secondary notes through this exact same information whatever here you'll find it under the RC transfer as well which is including a measurement report information to from from secondary n to also to the serving s b and this information including the coverage RS and once it's and

BCI as well primary primary cell identity and physical cell identity so once it's being received by the 5G nde the 5G node will evaluate this information and if it's found that this cell is already for example in this particular example it's found that this cell is not is not under it's not under this it's not configur it's not part of of the cells which is under this particular Noe so it will forward this message which is called secondary reg be change required to the master node telling him that this PCI is not under mine so

please check where where you can find this and it will forward this kind of information again to the master once it's being here the the serving the 4G nde will will evaluate and check whether they have this in their for example configuration nebor configuration so if it's found yes it's another neighbors so in this case it will do an addition exactly same as what we have explained in the previous session session so it will send this kind of information the BCI information for this target node asking him to add it and here the target node

will evaluate now this kind of information and it will respond withb addition request acknowledgement and this one will include all the information regarding the SSP and also BCI and all the information about this nde which is want to be added for this particular users just one quick thing that will also Trav shoting method so assuming here now there is a missing neighbors between this secondary Master node serving Master node and this target secondary node or B so in this case yes there will be attempt at Point a which is at B change required but if

there is a missing neighbor or X2 definition for example issue between this one and this one in this case the handware will fail right it cannot complete and it cannot send this kind of exision be addition request and it cannot find if missing nebor if X2 also will be the same same issue so this is also one of the things that might make Handover issues or problems that missing neighbors between the especially for the inter Handover inter Jour be Handover so in this case yes you need to take care that all the neighbors is being

defined from 4G to your neighbor side so here the information forward and here this one including exactly the same information this usually contains all the relative configuration R parameters timers also the SV frequency of this part and and also the BCI and everything so it will be added here so once being completed the user will be responding with Rion complete and here also will be confirmation from the master the master no to the serving one that okay SB change already done completed so this will be count as successful Handover at this particular point then also

this will be responding again the master new to the Target be that okay to be configuration completed then the user will initiate ratch process and once the ratch process being completed now we moving to this particular part that you find that the serving all serving 5G nde is being forwarding something called SN status transfer what ises this SN status transfer refer to so in general SN status transfer if you look if you look into that part here you find that here this message is sent from The Source 5G for example Network to the Target ngan

supposed to be sent from this one to this one to transfer this kind of information which is related to Uplink down link btcb SN and something called HFN is stat during and over all connectiv so here in this case I will explain both what what it means by both of them so here if you find this message it's initially following from it's serving it serving 5G to the master node then exact same information will be forward from this 4G new to the Target 5G new and actually what it means by by F information just for

your knowledge BCP SN this is referred like it stands for as you know BCB backet backet data convergence protocol and SN refer to sequence number actually so this is like it's bpsn is a sequence number used in 5gbp layer and actually it's used to sequence and resemble the backets and this is like for example to ensuring or ensure that you are received and processed in the correct order and and to avoid any backet loss during the transmission in general so just like this this kind of message is to align what kind what is the last

receipt sequence number for example of the backet so to be able to to know like and to to be able to order or to reassemble the pet in a correct manner this is the first part second part related to something called HFN and this like actually it's it's stands for hyper frame number hyper hyper frame number and this actually in general represent a high level frame number that's used to synchronize and coordinate various aspects of radio interface in general like for example radio interface including for example the scheduling or the handovers and timing as well

so in a not it helps to manage the overall timing and synchronization of the radio interfaces within within the network so this is kind of information will be delivered all the time during the and and you can see that even in the for netw so this once it's being completed now you will find that the serving it way is still forwarding the data still foring the data towards the the the serving the old the old even though the Handover being completed so still the path is going from this serving it way as you can see

in the top right here to this Source in not b Source J be and the transfer is still going through the X2 if you speaking about the user plane now so in this case yes the the data forwarding should be change right so still you find that the foring is being here and is forwarding this data to the Target just to inform that there still a data in goinging from the serving gway so in this case The Source in be the The Source Master node or Master node in general need now to change the path

from here to be to this one so it will send this modification indication which contains IBS new IBS of this target SB asking the mme to change the PA of the control plane and asking the serving gway to change the path of the Ser the user plane so once it's being done the the mme will notify the sway this is be modification would like to change the beer from this serving to the new Target one to in order to send this kind of data forwarding to be done directly from serving it way Target one so

once it's being received this will send end marker for to the master nde and serving it n s old is serving J B so it will tell him okay now I'm not going to forward any that anymore and it will send a confirmation so once this being done if you look into the top right here now the bth will be created so now the data will be transfer and once this being received now theion be Master node will will release the connection from the serving Gateway from the old one the old releas now I would

like it will take some time but I would like this is will be more beneficial for you I will open message by message just to explore how we can do the trouble shooting and also how what kind of information we need to look into for example during the Handover process so now let's start first with Mr actually we showed the chart for ration but I would like to start this one for one purpose so let's me open the message and see what we have so for example now I'm opening this measurement report and actually I'm

opening the RC transfer it's it'sing the same information but I just opening the r transfer message and you can see this is the figure on the right here and this is all the information which you can find it you find some information about the x2v ab ID but the most more important information if you went bottom down here for example you will find the first part here called on RC you will find that this is measurement results there is something called measurement id2 and this is very very important I will explain why then you'll find

some information about the serving cell for example here is selling that serving cell id7 and primary or the BCI is 311 then it giving information about DV and actually the information is 58 and just to calculate the final one it should be 58 - 156 so this means the serving cell having a coverage ofus 98 dbm and same for rsrq you just need to divide by by two and minus 43 so this will be the rsrq so in this case I don't know the Handover will be triggered through rsrb or rsr because we didn't look

into the RS3 configuration I will go for that but I I need you to continue or beer with me for that part then you'll find again this PCI is being repeated here you'll find that there is another p information was a new coverage so what it means by that and this is still for the serving cell if you look into that this is saying serving cell ID and this is the measurement for the serving Mo or the serving all list so we have two primary this means this this site or this serving cell having one

primary cell SP cell and secondary cell which used for car agregation for example 5G so this is for example for another one but I don't know this is for which carrier or for whatever this also can be checked from the previous RS messages so this is also presenting a cover that this is my E3 dbm then if you went down now we'll find this is one now called measurement result neighbor s and this is having a BCI 55 and now it's having a coverage of minus 190 dbm but I don't know yet this is for

which event event is it intra frequency inter frequency and over from what is the current SSP and this kind of information so in case if you're doing trouble shoting and you don't know exactly this is related for what the first thing you need to do is to go for this if you low go up here here you'll find something called measurement ID 2 so in this case you need to take this measurement ID 2 as a copy then you'll go to the previous for example R serion message and start looking this is equivalent to which

frequency this is a first point and equivalent to which event and this is very very important for trouble shoting and also I have a video about that part you can look into the trouble shoting part but let me explain quickly how we can do that through looking in the previous RS so now I I have opened the RS message which was before the UE delivered the measurement report message from here to there and the user is delivering based on a previous delivered information related to the events and other PRS as well now I would like

to see this measurement ID which is being seen within R transfer or the me which measurement ID to is equivalent to which event type is it inter frequency inter frequency or equivalent to which kind of of frequency for example or SSP for example here this is the beginning of the message it's very long it's having a lot of information we not explore all of it now so for example this is a called RS conation message which is being delivered during the NDC setup so what you need to do in that case you just need to

take this measurement ID as a copy then you go to here and search for this value measurement ID to for example Lo into find next usually it's at the bottom very bottom down you can see it's taking the message down here then you will find here there is an something called measurement ID to add mode you have measurement ID 2 it's having equivalent something called measurement object ID one and Report config id2 so in this case if you take this one report measurement object ID one and search for for that one this will give you

this one used for which SSP or which Pand so let's search for the same measure object I want and just move up here so you you can see now this one is stay frequency here and this is a Kilz sub frame number and the prity of the in in general sorry for the SSP which is every every 20 millisecond H subframe then you'll find that this is rated to B for example N8 so now we know that this N8 so if the S 78 this confirming that this is might be inter frequency but this is

still not enough I would like to take you again for the same one and look into the last one which is will confirm this one related to which which actual event directly so we have this report config to now if you look into that now here again just search for it go up you'll find okay that's good this one actually as you can see report config id2 is report related to event E3 uh measurement so now it's saying that I have E3 opset rsrb was six and the hysterisis is two time to trigger is 6

400 millisecond and this is the most three common parameters and you have another for example related to the report quantity for example in the measurement report there is three things reported RS and rsrq but which one will be taking evaluated by the 5G n to take the hand over so in this case it's based on RS on in some Networks can be also rsrq but rsrb is is more is more used for sure we don't usually use both or or rsrq we just usually use rsrb only so this is all the information related for that

part so now we have this is A3 and you have the offset and the hisor is and time to trigger so just in case here you have six and two this equivalent to if you divide it by two because the unit usually is 05 so if you divide it by two and this one each one by two so at the end you will have 3db and this should be the the bet the neighbor should be better than the serving this one should be better than serving with 3db for 640 MC in order to trigger this

kind of measurement so this is actually how how you can map this measurement ID to the equivalent event so the next next one let's to go through the remaining message and see what we have so in this case once you can see once the this RC transfer which is this message was sent from the 4G to the 5G serving 5G so this is s change required was including this candidate information for this kind of BCI so the 5G will look into this information and start to check whether it's part of their configuration or not so

if it's found that it's not part of the configuration it will return back something called SB change required with saying that okay this it's not mine you need to search for this candidate it's under which nde but it's not mine so it will say that now we would like to change completely my S to be because this doesn't doesn't included in myself so initially if you open this message which say to be change require you'll find that you will find that what is the kind of PLM identity also GB ID and also the cause what

kind of course for example here this is a cause of scg mobility and many other information important information so for example here I would like to search for this PCI see what we have just take this one as a search you'll find that this one usually is asking it to give it as a candidate see here for example in this case it's returning back almost the same information telling them okay see this is the C sell INF SSP is this information and the measurement ID is 505 the B is 505 and this is kind of

and so on and this is actually also delivering other information to data split but this is not our our context now or our subject now so it's returning back that I couldn't find this it's not mine so please change this be change change it to this kind of information so now what what we'll do the forg nude will look into this PCI in their in their configuration neighbors if it's found that there is a p C related to another note it will forward now it will try to add it as exactly the same which being

exp but let's quickly explain as well will explain this kind of messages to we expecting that decision B will ask the target exision b to add this kind of PCI and SSP frequency so let's open theb addition request again and see what will happen so now I'm opening this I open already theb addition request here this message after the change record being sent to the 4G now the 5G the 4G is sending to Target node asking and I would like to add so for example here this is It's required to change a b primary secondary

cell or a P cell so if you remember in the very beginning I explained that there's a concept of this naming of the SP cell and this cell and so on so in this case you can even search with the BCI or search for the SP cell SP cell SP cell secondary primary cell so if you look into that part so it it initially dis mates which is be addition request it's covering the information about the current serving cell for example the current serving cell for the SP cell is this n78 and also the the

BCI is 311 and 7441 is for the SSP frequency and also if you remember we Ed to have the same frequency for another band which is was related to the secondary cell not the for the car aggregation so if you look into this for example you'll find something called to add to mod list as well this is also still for the serving site this is still for serving site which is 311 as well and also the frequency and n41 so in this case now we'd like to see where we can find this kind of 505

so if you look into something called candidate so after looking for this candidate you'll find for example candidate sell info list for the master node okay it's saying that this one measurement result to NR which is exactly the same which is being here 74 412 and also the physical C ID which is 505 and the RS rsrb and rsrq so once this message is being received actually which is SB addition request here now this target SB will evaluate this kind of information and will see whether it's being can be added or not and it will

it's part of their neighbors soorry it's part of their configuration not so then it will send this is should be addition request acknowledgement including which cells it required to add even as a primary cell and or even as a secondary cell which is Rel to the car aggregation and for sure this will be based on your current cation so now let's open this addition request technology and see what we have so now I have open the message which is sent from the target s 5G n to 4 which will be asking them I would like

to add uh my second Prim cell information we sharing we expected to find all the information for the secondary primary cell related to this not to the 4G and the 4G later will be following exact the same information which being included in this message through our information so now let's explore this message and see what we have so I'm expecting to see this one which is information for the candidate cell info which is being added sent before an addition request and I expect to see this one as a a secondary primary so I will just

search was for SP cell SP cell so this is referred to secondary primary cell so if you look down here so I'm exped to see exact the same information which is above here for example if I'm moving down I have here this is sp frequency 7 4412 and also I have this PCI 505 and now I have the frequency band which is uh for example B 78 and point offset point a which is UND defying the beginning of the band actually have video in details related to the SSP uh frequency allocation this is explaining all

the related details about that part but this is just simply to identify where is this sspi okay the user know where ISP location now but he want to know where is the start of the band Channel band so this is usually frequency and also give you information about the carrier bands and even if you move down start exploring you'll find information about the bdcp also I have one video about the bdcp part then you will find uh other more information measured it to the for example and if you're moving more and more about the B

bdch also patterns and many other information even timers if you move down C cssi uh and also the timers I would like to see you the timers for example if you search for t304 find where is the timer as well for example here you have the timers as well okay so this is all the information you'll find it in this message in case you would like to do any audit or whatever for the network so so this is including again as a summary including the the cells which is 5G cell which is required to be

added to this users but if you remember in the measurement report there was two reporting FS related to the secondary primary cell and also there is something to S cell right which because there is a cartion so we need to know like whether also this requesting to add additional s or not if you remember the naming if you speak about the cartion you need to search for something C in case if it's required to add something to the cation it should be called s to add two mod to search so yeah okay now go down

going down here you'll find something called sell to add to mod list now it's requesting yes I would like to add this physical cell ID which is 874 and this is a frequency and frequency band and this is a SSP so as you can see now it's asking to add two actually one as a primary and one as a SC aggregation was with that part as well and this actually there was no measurement if you remember there was no measurement includ about about that part in the the RC transfer for the Target I mean Target

SB so only the the one which is being sent it was 505 for the neighbor so this means there is a blind configuration in this kind of of site this is like uh my explanation for that part so now I'm expecting now are expecting the exact same information be forward from the N to the from the master no 4G 4G to Z this will include exact the same information here now we have this confirmation that I have received this message once we have this message now being received let's take this down just continue again we'll

complete with the remaining process related to the be confirmation and SB compation complete here and we will start the ranch process I would like just quickly explain again for the SNS transfer just show you quickly what we have in the message then we'll go move forward for the remaining so as explained before this is an stat transfer just including this information which is important related to the sequence number of the BCB and the hyper frame number as well just to align the the frame and sequence of the orders of the packets and for this is

the main information you can't find it here as a quick part and ending by by that part the ER modif indication will include the transport ID and GTP idea as well I have also explained this one in the addition so now this is being done we'll move now to the simple one which is related to the in Handover it will be next slide as as you can see now this the primary secondary C change but this time it's inter be within the same side so this is actually it's very easy one as you can see

that initially the measure being sent will will cover exactly the same information being explained before and we'll be have RS transfer then we'll have this SB modification request required so let's open this message quickly and see what we have in this message so before opening these two messages I'll would just like to take you into quick overview about that part of the right so as you can see this is just intra intra inra intra be hand over that's why it's between the same s so it's okay and assuming this is inter frequency and over so

in case of inter frequency it should have the exact same SSP position and if in case of inter frequency and over right it should be like this SP position even if it's within the same band assuming the same band but this SP position is different this will trigger inter frequency hand over so just like quick recall also recap for that part that the Handover is mainly controlled by the SSP so it's the it's not about same it's not the same concept of the 4G now thep can location can be different in the band so even

within the same band same sorry same band you can find the different position between cells this can cuse interfe so now let's open the messages let's open the messages for the other things which you have it for the this measurement report and this required to see what we have so now I'm opening here on the right you can see you have here the measurement report being sent so in this me boort if you again explor it I'm opening in the top left here if you go down here again you should find the serving cell and

neighbor cell information as well so here there's a serving cell information which including BCI 310 and we have DBS d q and moving down here you will find also the again repeated for the serving cell 310 which means that you have car agregation for this site this second information for the secondary cell for the serving which is also that part then you will find the measurement result neighbors as well which is PCI 309 so now once this being received by the s b serving it will evaluate this kind of information then it will request through

that should be modification required from the foru to start adding that part through our information message so we expecting again if you search for exactly the same information for example this we found that should find this SP cell under the SP cell which is 309 so for example if you search for a spel you'll find yeah for example okay good so so you find SP C configuration okay I would like to add this one 309 as a primary as my SP cell primary cell as a 5G leg so it's asking the 4G to do that

so again include the information frequency band and so on and again will cover all the other information and in case if you like to add also a agregation cell so you need two cells for secondary cell chain secondary cell add to Modas this is referring to car agregation so yes it will be adding also secondary cell band 40 and for example BCI 309 so this is actually also the exact same information and now our cation will cover exact the same information being here and once completed would be confirmed and now there is a random access

but if you look into that that that scenario you'll find that there is no path switch because no path switch change because this is already inen B so the path is still will be going through to the same node actually for that particular case so this is explaining that part and this is more easy as well but one of the important uh things I would like to to highlight you scgb modification required in general can be for many different things it's not only for this cell change for like for that case for example SB modification

required can be for any parameters or configuration change within the theion be in case there any change and requir to inform the user so it need to for for example if you have a change in the uping thata split so let's assume that for uping that split I have also video about uping through Buton you can look into that part if for example assuming the user now would like to fall back to the 5G Network or stop the splitting for the Uplink so this kind of information should be delivered from to the master B to

request the user for example to stop doing up blink splitting as an example so in this case it should be modification requir will be sent which covering the new information for example this feature for the uh DRX for example if you have change and DX also be send it from here to there also for the link waveform feature as well this can be if there is any change the user is moving from for example from one layer to two layers or whatever for this Uplink feature for the CB of of dma and so on so

this will be also sent from the information sent through H&B modification required what I won't say that modif required yes it's during the ENT Handover but also it can be used for another things as mentioned here for example gab request change or any other configuration change within the site and on top also primary secondary C change and also sometimes you'll find modification requests being sent from the survey Unit B to to the 4G also asking about some change for example if would like if this case let's assume that you have interf frequency measurement is being

going so sometimes here there will be any step before that ration it's not mandatory but something find it that this will be providing for example something rate to security or the Gap information to align the Gap information between the source and the target and sorry and the 4G and 5G node so this also will be sending before that step being completed to sending sgb modification request which is including the information which required to be aligned between the five five 4G node and 5G node so there also this extra information you need to consider as well

whenever you check because you might find some extra step and some cases as you mentioned you will not find this RC transfer because modification required maybe required for something else and modification in general means that you are changing something then the for example configuration or a Handover as this case so now let's move to the next part which is related to the just just quickly I not go through details for that part but just for example explaining that whenever you have Handover in the in the in the five 4G n as you can see here

for example there was a Handover from the this nde this is inter inter in Handover from The Source no to the Target node as you can see hand over request being sent from here to there and once being sent now there will be a change for the secondary cell change so this one will be sending again addition request from the beginning so again the change of the secondary cell can be also triggered by the Handover from the 4G nde this is as well like this is just sign from reference it's just rated majority 4G and

this is just main main take away from here that 4G also frequent handovers can impact the 5G performance for understand alone so you have to take care of that part as well so yeah this is for inter for example INB Handover which being also this will be requesting additional change for the adding the new information for the new Target is be and also will release the old one and exactly the same for the inter be Handover but this is can be done without a s change for example there is inter B Handover being done but

they are sharing the same secondary sell change so in this in this case the Target Master node would request from the serving serving that I would like to add you and once it's being added the old one the serving old serving will release this kind of information from the serving J so this this also another information and this is having both CH both switch change at the end for that that part as well because this inter then moving forward now this is related to the the parameters actually in general the parameters as you can see

here I just give the list is the most common parameters but you have even more param than than that but just to explain quickly because sometimes you see this figure and might get confused so for example this here speaking about wi parameters you have A3 A2 and A5 I'm just listing things the most common inter frequency and Inter frequency and over so assuming that you have E3 this is a form for inter condition you have many things like OC ests for example this is related to you have CIO for example sell individual offset and frequency

offset this also can be added but usually with tune this three and others maybe for examle C can be them through some features so for example here here you like this is the most three common parameters if you look into this figure this just explaining when the Handover will be all when the measurement report will be sending from the to in so for example now assuming that that this blue line is for the neighbor cell and the red one is for the Ser cell so you can see till now here till here this is for

the serving cell you have an offset so the neighbor should be better than the serving cell in order to trigger the hand over right in order the U2 measur but for how long or what's the offset so now it's adding this you have E3 Offset you can see so this is the neighbor S as you can see this is a serving so this is nebor it's adding off to that this hes first here this me then the offset for example so the neighbor should be better than the the serving was offset pluses right neighbor should

be better than the serving was offset pluses so here here this being achieved both of them so here this is the first point that the user will start the time to trigger because already the neighbor is better than the serving was offset and the stresses A3 off and the stresses so it will start time to trigger assume that time 640 Mill so if the neighbor keep consistent better than the serving with the his offset for 640 millisecond in this case the user will start reporting the A3 report to the ENB and INB will transfer this

information to J B and it will continue the same as that what what we have explained before and just that this is also exactly the same for 4G as well so exact same information and there is some details about that part in 5gr in bullet box and also I think it's already covered in many other information last part with the like to end with is most common failures in in the it's not actually frequently happens but this is like in general I try to collect whatever cases I am aware I'm a or I have seen

from seen before so for example you have as highlighted before you have this missing X2 definition or missing neighbors usually the missing neighbors is not causing Handover failures and speak about the for network but in 59 it can cause even X2 or missing can cause why if you remember this figure we we explained in the beginning of this session for example here in this case in the inter be hand over the UE reported the the Mr report send it from U to mement report then this one being transferred to serving J B then the Serv

send SB change required because this was not part B is not it's not part of this kind of cell so here in this stage the for received this information of this which including the BCI for this new Target so if the neighbor is not defined from for this for to this one in this case the Handover will not be successful hand over attempt already be counted so in this case there will be no response from the 4G network because this is already not defined so it cannot be so this means if the missing neb are

there between the 4G and this for the enter J be Handover in this case this will cause a failures hand over failure and also mixing X2 definition assuming there is no X2 Define between this one and this one the same will happen for any message exchange between both of them so this is also why why it's happening also for sure if you have P conflict this is also something nor and sometimes if the target nude having admission control for example having high lad in users or license limitation or or whatever depend on each vendor specification

and also there's a transmission issues impacting for examp the X2 length and sometimes honest speak I didn't see it that much but sometimes there is some rare cases where there is a capabilities during the Handover which is refusing the target cell will be refusing the the uh the Handover and this is sometimes you can optimize that to different the vendor have different mechanism of that part and this is also one of the rare cases which you can see this is the kind of a risk condition like if there is already ongoing Handover and there was

a it's to be modification being sent from the 5G n to the 4G n in this case the 4G will rejected will send 4G will rejected by modification refuses and it will contain this kind of compatible those receiver State and that's indicating that there is already ongoing procedures for Handover in the 4G which is called risk condition or signal interference that's why it's preventing the handovers and this is also also mentioned the cause of that mentioning the 3bb here as mentioned in the source so that's it for today's session um I hope if you like

the session to spread the knowledge and share it with your friends and to like and comment and please share your comments and feedback feedback your feedback is really needed to keep optimizing whatever cons I'm trying to present and also I would like you I would like to request you to to to send whatever contest you would like to add for the series of the 5G stand General to make sure that we have a complete understanding about thank you and see you in next video