HO Fail message with cause channel mode unacceptable

[saidou]

Dear All,

I investigate on an issue that I face now in the network, I get some message during Actix drivetest where many HO fail occur with message "Channel mode unacceptable".

If there is some one that face same problems, plz share it .

Thanks

[rnpopt]

Please read the following lines from ETSI document:
"If the ASSIGNMENT COMMAND message instructs the mobile station to use a Channel Description or Mode that it does not support, then the mobile station shall return an ASSIGNMENT FAILURE message with cause 'channel mode unacceptable', and the mobile station shall remain on the current channel(s) and uses the old Channel Description or Channel Mode."

[manson]

I'm a problem with Intracell HO with same BCCH and same Cell...
one more, Intracell HO Failure between TRX in same Cell.
Enyone, can help to discuss the Case or some one that face same problems, plz share it .

[punto]

@manson

-check HO parameters activated in cell, if is new one in network ... could be BSC admin mistake

-see if cables are maybe swapped between two sectors .... could be mistake during installation of equipment
BCCH TRX good cabling, other TRX cable end up on antenna on different sector antenna ...

-check HO statistics with declared neighbors if is logical amount of numbers ... diagnostic search

-try to halt second TRX for couple of hours to see if statistics will become better ... test if there is bad HW problem in your bad cell

- go to field and play around with halting of TRXs or send guys to check cabling at antenna and BTS connectors ...

tell us some more data, could be lots of things ..

let us know if is OK ...:)
P

[maasricht]

Hi,

Is it ******** system?

Because of When I was working in ********, I saw this problem. At that time, 2 cells are border cell, and one of them is EFR, the other is AMR. From AMR to EFR Handover is ok, but the other way is always Handover Failure due Channel Mode Unacceptable.

When I changed EFR to AMR, Problem is solved.

[saidou]

Hi,

For the ETSI specification I have already read this definition but what I'm asking for is what will be really the problem.

The most cases faced is when performing HO from a non AMR cell to AMR cell and the first HO fail was with "unspecified" cause after the all the HO fail are with cause channel mode unacceptable. What I have noticed is that the HO command send don't give in details information about the set of codec used and the threshold.

I'm asking for this kind of HO fails do you face this kind of problems what ever the supplier.

BR

[rnpopt]

As you know in AMR FR or AMR HR you have to mentioned the different channel codecs(maximum 4 codec) which should be used.
As u mentioned that HO failed from EFR to AMR, i.e. the Target cell is of AMR , so the possible reason may be:
i)Either the MS is not supporting the initial codec mode which is configured in the target Cell.
ii)You have configured the wrong codec set for the target cell.
the 1st one cause is more reasonable.
what you guess??? :)

[maasricht]

I wrote it. I had same problem. This is vendor related problem.

- Check AMR Settings
- Change non AMR to AMR and test it again.

[saidou]

I have test it but it seems that this fail is random, which mean that I got a fail but if I re do the drivetest nno fail happen.
I also check the phone but I have noticed this issue using 2 differents phone.

[ghassen]

Please read the following lines from ETSI document:
"If the ASSIGNMENT COMMAND message instructs the mobile station to use a Channel Description or Mode that it does not support, then the mobile station shall return an ASSIGNMENT FAILURE message with cause 'channel mode unacceptable', and the mobile station shall remain on the current channel(s) and uses the old Channel Description or Channel Mode."

somtimes i think but not sur it happen due to wps (wireless priority service )and then the HO will drop or due to also service layer must check it

[maasricht]

I have test it but it seems that this fail is random, which mean that I got a fail but if I re do the drivetest nno fail happen.
I also check the phone but I have noticed this issue using 2 differents phone.

This problem appeared randomly, I remembered that I tried to catch this problem nearly 3 hours. This is not related phone.

I am saying again, check AMR - Non AMR cells, and BSC border cell or not?

[saidou]

I think that I found some thing, this a software bug in BSC when preparing the HO, I'll summarise : when a HO is performing from non AMR cell to AMR cell we should found in the HO command a multirate configuration (set of codec and threshold), but 1st an HO fail occurs with message "protocole error unspecified" which mean no connection in layer 2, after that, a new HO command is performed to another cell with channel type AMR but in this time no Multirate configuration is included in the HO command message which mean 1 thing : the BSC doesn't include this information because it see that the mobile is already in AMR channel type (which is no the case), later an HO fail occurs with message "channel mode unacceptable".

from what I found, the BSC doesn't update the status of the channel type of the mobile after the first HO fail.

[basith.aces]

I'm a problem with Intracell HO with same BCCH and same Cell...
one more, Intracell HO Failure between TRX in same Cell.
Enyone, can help to discuss the Case or some one that face same problems, plz share it .

Dear

I think "Intracell HO with same BCCH in same cell" means

HO between time slots

one freq consists of 8 time slots so the HO between Time slots is the reason for Intracell HO with same BCCH.....


please push for rep and thanks button
BR:hug:

[hassen]

Dear All,

I investigate on an issue that I face now in the network, I get some message during Actix drivetest where many HO fail occur with message "Channel mode unacceptable".

If there is some one that face same problems, plz share it .

Thanks
hi saidou

I think you made investigation with Actix drivetest
could you make it with Tems investigation and do comparaison in order to be sure
of result of causes.
let me know
and btw can you check transmission line mybe your problem is related to synchronization between bts (serving cell and target cell) and as you know
it is very important other way Ms can't reach the channel assign (time offset).

br hassen

[manson]

@manson

-check HO parameters activated in cell, if is new one in network ... could be BSC admin mistake

-see if cables are maybe swapped between two sectors .... could be mistake during installation of equipment
BCCH TRX good cabling, other TRX cable end up on antenna on different sector antenna ...

-check HO statistics with declared neighbors if is logical amount of numbers ... diagnostic search

-try to halt second TRX for couple of hours to see if statistics will become better ... test if there is bad HW problem in your bad cell

- go to field and play around with halting of TRXs or send guys to check cabling at antenna and BTS connectors ...

tell us some more data, could be lots of things ..

let us know if is OK ...:)
P

All sectors, no cross feeder, No Interference and Hardware using AMR full rate... Configuration is 1 TRX..

Usually... Intracell HO Failure like that, happened after we change BCCH No. because of Interference. But After no Interference, Intracell HO becoming often happened.

We check in BSC at RNC, No data HO Failure but if we actual check in BTS, Intracell HO Failure same BCCH always happened and resulting DropCall...

[manson]

Dear

I think "Intracell HO with same BCCH in same cell" means

HO between time slots

one freq consists of 8 time slots so the HO between Time slots is the reason for Intracell HO with same BCCH.....


please push for rep and thanks button
BR:hug:

Yess.... I think like that...
So, what is the solution for this case??? What parameter Huawei to disable Intracell HO like that... ???

[adedia]

Check whether TRX Board are OK or not. Some defect/faulty on the board might cause Intracell HO due to bad TS. To do this you can swap TRX. Choose on problem one and test it.
Well i don't think we can disable intracell ho.
Since it's the way to survive the call whenever call quality goes bad.An no hopping are implemented

[adedia]

Check whether TRX Board are OK or not. Some defect/faulty on the board might cause Intracell HO due to bad TS. To do this you can swap TRX. Choose on problem one and test it.
Well i don't think we can disable intracell ho.
Since it's the way to survive the call whenever call quality goes bad.An no hopping are implemented

[RF engineer]

Did you check the TRAU pool does it support AMR speech. because when the TRAU is not configure with AMR support this problem appear normally TRAu as Default Support EFR,FR and HR.

[saidou]

hi saidou

I think you made investigation with Actix drivetest
could you make it with Tems investigation and do comparaison in order to be sure
of result of causes.
let me know
and btw can you check transmission line mybe your problem is related to synchronization between bts (serving cell and target cell) and as you know
it is very important other way Ms can't reach the channel assign (time offset).

br hassen

Hi Hasse,

I have made investigation with both Actix and TEMS and it seems that this fail happen always with the same scenario : the 1st fail is always with cause protocol error unspecified and after that a series of HO fail with message channel mode unacceptable.

about the TRAU and transmission we have also check this track but no problems. we also made drivetest in different region and no problem occurs.
.
BR

Said

[hassen]

Hi Hasse,

I have made investigation with both Actix and TEMS and it seems that this fail happen always with the same scenario : the 1st fail is always with cause protocol error unspecified and after that a series of HO fail with message channel mode unacceptable.

about the TRAU and transmission we have also check this track but no problems. we also made drivetest in different region and no problem occurs.
.
BR

Said
if you use baseband frequency hopping and as you know
Ms connects from trx to another, if one of these trx has a problem it will be dropped.
disable one of trx step by step and check KPI ,if traffic increases on target cell and incoming HO improve it is the reason of the problem.
otherwise check FER mybe in this area there is external interference.

[RF engineer]

Can u please tell me what is your vendor

[manson]

the vendor is Huawei ;)


Can u please tell me what is your vendor

[RF engineer]

Do you use BSC32 or BSc6000 if you use BSc32 then configure(Set circuit pool of A interface to 27) and for BSC6000 configure(Set the A interface Tag to GSM_PHASE_2+).

[RF engineer]

Also if you A interface is set correctly according to above which i mentioned then one more thing you have to check is the cells ACS for FR must be 4 code and for HR must be 3 if it more than this it makes this problem and second reason it may be the Threshold and hystersis not configured well.
And if it is possible to send the logfile for my email
aso.jumaa@gmail.com
let me see more detail in you drive test

[manson]

Do you use BSC32 or BSc6000 if you use BSc32 then configure(Set circuit pool of A interface to 27) and for BSC6000 configure(Set the A interface Tag to GSM_PHASE_2+).
we use BSC6000 config...
Could u tell me how to set the parameter, please???
Thank's...

[RF engineer]

The attach is the parameter setting for BSC6000

[RF engineer]

BE careful the binary code for ASC it may be different from which i sent if it is possible send just the binary code in speech version in call parameter.
BR

[alexfokin]

we have experienced this problem when we havent amr codecs in our trau

[CERTISCJS]

informative and good