Handover failure Reason using TEMS

[Areej]

Hi, all

Could the congestion be a reason of handover failure ??
I mean if (Handover Command) message is found , can I consider the congestion one of the reasons ?
check the attach

[adewijaya]

yes, it can. HO block due to no channel then will be directed or back to old

[Areej]

yes, it can. HO block due to no channel then will be directed or back to old
But some engineers told me that if the MS got the the handover command message that means that a traffic channel was found and so no congestion on the target cell.

check the attach pic. please

[K4CrUt]

Can You give us another link of your attachment because i can not view the attachment, thx.

BR,

[adewijaya]

your data not describe about that, in HO process there are block (due to congestion) and fail (return to old channel or redirection)

[Processor]

Hi, all

Could the congestion be a reason of handover failure ??
I mean if (Handover Command) message is found , can I consider the congestion one of the reasons ?
check the attach

I advise you check the stats for the intended Target cell before concluding cos u could experience HO failures due to so many reasons.

[Areej]

I advise you check the stats for the intended Target cell before concluding cos u could experience HO failures due to so many reasons.


yes of course I know
but my question is :
even though the MS got the 'handover command' message, Could the congestion be a reason in this case , or as soon as the MS get this message I can't think of the congestion?

[adewijaya]

i think message for congestion will be receiving on source cell then controlled to other decision to redirection or return to old

[Areej]

Can You give us another link of your attachment because i can not view the attachment, thx.

BR,


here another one

http://images****.us/content_round.php?page=done&l=img192/9610/fffiff.jpg&via=mupload&newlp=1

[Areej]

Can You give us another link of your attachment because i can not view the attachment, thx.

BR,

I don't know how to put a photo in the forum

[adewijaya]

your picture is OK, we can seeing clearly. Your question already answer well, isn't it? :)

[theumar@hotmail.com]

HO Command send by BSC with information of target channel after Channel Preparation in Target Cell. In this case HO CMD sent but HO Failed because MS was not able Access Target Channel, it could be because of Interference at target channel or poor UL condition of target cell

[Areej]

HO Command send by BSC with information of target channel after Channel Preparation in Target Cell. In this case HO CMD sent but HO Failed because MS was not able Access Target Channel, it could be because of Interference at target channel or poor UL condition of target cell


but congestion can't be an option after the command is sent right ??

[adewijaya]

HO Command send by BSC with information of target channel after Channel Preparation in Target Cell. In this case HO CMD sent but HO Failed because MS was not able Access Target Channel, it could be because of Interference at target channel or poor UL condition of target cell

Question is : capacity could be became reason to rejection HO or Not? just that and i said : it could be aside due to Interference absolutely

[Areej]

Question is : capacity could be became reason to rejection HO or Not? just that and i said : it could be aside due to Interference absolutely
Capacity ofcourse one of the reasons of HO failure, but the question here , if the MS got 'handover command message' - which means that a traffic channel is already found - and the handover failed , I can't think of the congestion as a reason ??

[adewijaya]

not directly affected, on statistic separated two kind : Block or Fail, so HO fail isn't related to Congestion but HO block it could be due to no channel

[leelio]

you can try to check which cell was chosen to be handed over a call, & does that cell experience congestion in that period? (you can see this cell during handover command)

sometimes delay in handover happen and may cause wrong interpretation.

[Areej]

you can try to check which cell was chosen to be handed over a call, & does that cell experience congestion in that period? (you can see this cell during handover command)

sometimes delay in handover happen and may cause wrong interpretation.
the problem is that I don't have access to check the congestion on the cell
I only can use the events and layer 3 messages and TEMS windows to investigate :)

thanks anyway

[salmeterol]

When a telephone gets a "handover command", that means a radio source allocated for this phone on target cell. TCH Congestion is not a HOF reason.

This allocated source is a TCH Channel, not a SD Channel.

SD CONGESTION MAY OCCUR AFTER HO DECISION !!!!

You cannot understand congestion status with TEMS. If you cannot get daily KPI values of target cell; then just take short call tests around it. If you make a Half Rate call; that means cell has high traffic and is closing to TCH Congestion. Means so many AMR HR-FR handovers happening in target cell => may cause SD Congestion.

Don't forget to check ping-pong handovers too...
Intensive handover traffics load SD channels.

Don't forget; there should be open sd channels for finishing handovers.
But these are rare exception situations.

You can check dl interference & dl quality problems too. Probably interference happened on target cell. Or target cell may be overshooting with bad quality signal.

Just go and take a test on roads between source & target cells and look for some problems.......

:-)

[fdanaei]

Hi, I think friends said main reasons for handover failure. But dont forget to check same BCCH+BSIC Problem. also existence of faulty TRX in Target Cell.

[the.rf.consultant]

The best thing to do is to look at the Layer 3 messages...

But with the posted image I can only conclude that there is a coverage or interference problem, because upon establishing a call on Cell A it was immediately handed over to Cell B.

Try to look at link quality problem and hardware/software incompatibility.

[zeezzoo]

let's stick with the main question.

dear areej yes handover failure can be caused by congestion :

first let's put this on mind : only BSC knows the load & how many idle TCHs on all the cells controlled by it .

1) inter cell - intra bsc HO :
in this case when the target cell has no available TCH ==> no HO command will be sent at all because both of the serving & the target cells are controlled by the same BSC . but this is a HO failure & it's up to the BSC to count this failure or not (depend on the software version) . kindly check the attachment named "inter cell - intra bsc" and notice that it's counted for siemens BR9.0 .

16887

2) inter cell inter BSC :
in this case the serving BSC that controls the serving cell will send "HO Required message" to the msc . the msc will send "HO Request MSG" to the target BSC . but the target BSC will not send "HO Command" to the target cell . here we also have HO failure and in BR9.0 siemens it's counted on cell level . check the attachment named "inter cell - inter bsc"

16888

so in DT when you see "HO Command" == no congestion & if you have handover failure , then it is caused by another reason .

but in case you noticed there's no "HO command" even though you have a good target cell to hand over the MS to ==> this can be caused by either wrong parameter settings OR congestion .

handover failure due to congestion are counted by BSC . and only you can prove it by using STS not DT .

hope it will be useful

[melkaiy]

dude check he power control parameter is setup properly, ho failure is mainly due to missing neighbor and if the cell is targeted, kindly check also the a1 events. kinly add reputation thnks man

[Areej]

I got it thanks all :)

[zeezzoo]

dude check he power control parameter is setup properly, ho failure is mainly due to missing neighbor and if the cell is targeted, kindly check also the a1 events. kinly add reputation thnks man

my friend we are talking about 2G not 3G . another thing : you can not ask for rep for every sentence you are posting .

[theumar@hotmail.com]

Yes its true, its not congestion issue

[zhanglw268]

Hi, all

Could the congestion be a reason of handover failure ??
I mean if (Handover Command) message is found , can I consider the congestion one of the reasons ?
check the attach
In your case with TEMs log, this is a handover failure and reverted back to the original channel, you have seen the Handover Command for the target cell, this means that the resource in the target cell had been reserved for this handover, the congestion in the target cell isn't reason in this case.

You can check the failure reason to see possible cause, also you can check the layer 2 messages to see how many handover access were sent.

The possbile reasons are list below:
1. RF Interference at the target cell
2. tight reuse of the same pair of BSIC and BCCH ARFCN
3. Same frequency but different BSIC, but same BCC may also cause handover failure
4. Synchronisation Problem
5. different ciphering settings between 2 cells which belong to 2 different MSCs/BSCs if you have ciphering enabled.
6. DL and UL unbalance, for example, TMA, DL signal is strong but UL signal is weak, this will cause handover failure
7. Too high BTS output power, too low MS power setting.
8. Lower power on TCH than on BCCH in target Cell Check power parameter setting.
9. low/incorrect handover power level in the HANDOVER COMMAND so target cell can't detect the handover access message
10. target cell problem that didn't send the physical information for non-synchronized handover.

If you are still interested to know the root cause for this call, please show the failure reason content and the layer 2 messages in other snapshots.

[adewijaya]

is it all discussion in here could answering your question my frend? :)

[Areej]

is it all discussion in here could answering your question my frend? :)


Yes yes

Thanks ALL :)