Call During Location Update

[usama0795]

Hi know its a noob question but was think how a call responds during location update; for example a user is a LAC boundary and is continuously Location Updating (No CRH in play) when that user sends a RACH what happens user is already on SDCCH so would BSC make the user wait till location update ends and then assign a new SDCCH???? OR does the MS behave in the normal way with RACH re-transmitted with timer T3120....

In addition in case of failure I mean if Location Update take the worst possible time i mean Tthen T3126 expirer or some other times???? is there any counter through which we can see this thing???


1. According to ITU standards Location Update Time <= 2 sec Intra-VLR (Only LA ID in VLR)
2. Location Update time <=4 sec Inter-VLR.
3. Worst Case scenario time for Location udapte ??????

[khurrambilal01]

If the MS is in dedicated mode and either it's on SDCCH or TCH then it receives pagings on SACCH instead of PCH, And it doesn't listen to PCH during dedicated mode but listens to SACCH. Even if you are on TCH call you can send SMS that is using SACCH as well.

[plannerguy]

Hi

I think ,In dedicated mode alerting happens through FACH,

Regards
Plannerguy

[tharinduwije]

Does anyone have a good document explaining the Timers & Location Update Behavior in Idle /Dedicated mode? Much appreciated.

[usama0795]

Thanks guys but still a bit confused for example the vendor is NSN and the feature ordinaryCallOnFacch and pagingAnsOnFacch are disabled then what kindly help IN CASE OF ORGINATING CALL HOW DOES IT RESPOND WHEN MS IS GOING THROUGH THE PROCESS OF LOCATION UPDATE IS THERE A FAILURE CAUSE OR MS IS ASKED TO WAIT TILL LOCATION UPDATE COMPLETE MESSAGE IS RECEIVED.......and are u sure abouth MS can listen to paging on SACCH never heard this one before I thought SACCH was only used for MRs.....

[khurrambilal01]

Thanks guys but still a bit confused for example the vendor is NSN and the feature ordinaryCallOnFacch and pagingAnsOnFacch are disabled then what kindly help IN CASE OF ORGINATING CALL HOW DOES IT RESPOND WHEN MS IS GOING THROUGH THE PROCESS OF LOCATION UPDATE IS THERE A FAILURE CAUSE OR MS IS ASKED TO WAIT TILL LOCATION UPDATE COMPLETE MESSAGE IS RECEIVED.......and are u sure abouth MS can listen to paging on SACCH never heard this one before I thought SACCH was only used for MRs.....

Yes sure in case your LAC is not changed and you are in dedicated mode then you can recieve call send SMS using SACCH,,, Sure about it.
But not sure in case if i am in dedicated mode and LAC changes but MS didn't perform location update..... So VLR doesn't know my new location but as i am in dedicated mode MSC knows my cell ID as well, May be some vendors have feature using which you can still recieve call in the new LAC even without location update....

I think this last scenario can be tested in DT.

[khurrambilal01]

Yes sure in case your LAC is not changed and you are in dedicated mode then you can recieve call send SMS using SACCH,,, Sure about it.
But not sure in case if i am in dedicated mode and LAC changes but MS didn't perform location update..... So VLR doesn't know my new location but as i am in dedicated mode MSC knows my cell ID as well, May be some vendors have feature using which you can still recieve call in the new LAC even without location update....

I think this last scenario can be tested in DT.

@ Hi Ousama,
I have confirmed by enabling signaling trace (HW BSC 6900),
When the MS is in same LAC dedicated mode, New second call was successfully recieved (& It was not through paging, It was just call indication message either on SACCH or FACCH & through tracing you can't confirm the channel type only DT can do that),

In second scenario MS was in dedicated mode and then it changed the LAC and no Location update was performed, Still in new LAC it was receiving the new call through same call indication message, that too through same channel SACCH/FACH.

So no paging is performed once MS is in dedicated mode, MSC knows the exact location of the MS so it directly sends the new call indication to the MS on same cell and because in dedicated mode MS is always listening to SACCH so that's why it receives the message on SACCH, can send SMS on SACCH.

If you are interested i can share the trace file.

I have seen another interesting information that once we are having conference call still we are having a single timeslot on Air interface.... We are not assigned to separate timeslots for each call...MSC just adds the two channels together on A-interface using Conference call feature.

[huawrx]

Does anyone have a good document explaining the Timers & Location Update Behavior in Idle /Dedicated mode? Much appreciated.

Please i need the same, i have one case, we have location failure due to interface not available, we have legacy sites surronding huawei sites but we don't find where is the problem, we checked inners, outers, but the problem still continue, please help