Huawei Call Drop Problem

[parsarka]

Hi Experts,
I am facing terrible problem in the GSM network with the call drops in all the BSCs suddenly rising & falling every other day but there are no major alarms(fluctuating from 0.7 to 1.5).We suspect there is some problem either with the MSC or with the transmission but not able to track the same.Please let me know the process to follow to solve this issue.
Regards
Raj

[neoone]

try to check tilt/degree of the cell

[sonerss]

All the BSC cells :o

Try another sollutions :)


try to check tilt/degree of the cell

[RF engineer]

Hi Experts,
I am facing terrible problem in the GSM network with the call drops in all the BSCs suddenly rising & falling every other day but there are no major alarms(fluctuating from 0.7 to 1.5).We suspect there is some problem either with the MSC or with the transmission but not able to track the same.Please let me know the process to follow to solve this issue.
Regards
Raj
check Call drop reason in Call drop measurement . it gives you some idea if it Radio part or other part.
BR
RF

[chokri]

Try to identify the time slots in the interface A wich cause the drop. You can do this with a protocol analyser. then you must block theses time slots and the problem could be resolved.
:D

[parsarka]

Try to identify the time slots in the interface A wich cause the drop. You can do this with a protocol analyser. then you must block theses time slots and the problem could be resolved.
:D

Dear Chokri,
Thanks somuch for your suggestion.Kindly give me some guidelines of how to use protocol analyser & from there how to identify the faulty timeslots of A-interface.Can it be done from the BSC end or at the MSC end??

Regards
Raj

[Cheuv]

did you face any BSC &/or MSC SW upgrade which may linked to that prompt increase of the Drop Call?

[parsarka]

did you face any BSC &/or MSC SW upgrade which may linked to that prompt increase of the Drop Call?

There were no upgrades done as i checked.I also like to mention here that the drop is not constantly high but keeps on fluctuating heavily throughout the network.So kindly suggest further.

[parsarka]

please help me on this

[kevin_h811]

Hi PARSARKA,

Have u tried to check TCH ALLOCATION STATS, to identify what TRXs causing High TCH FAILURE RATE and SDCCH FAILURE rate and etc..TA check if your site's signal is degrading correlate it with TCH alloc for TRXs causing it...Have u check your setting of Radio Link Timeout, SACCH Multiframe, T3105, there u can change the setting first if there will be improvement.
U can start from there first and if u found nothing wrong or improvement of parameter setting I gave, BSC to MSC isolation..

Pls add rep if u find it useful...if not, it's ok, badly needed...

Regards//

[parsarka]

thanks very much for your suggestions,I have added reputation to you.....the radio link drops are high in my network..please suggest some more parameter by which I can improve the drop cause due to the above reason

[parsarka]

check Call drop reason in Call drop measurement . it gives you some idea if it Radio part or other part.
BR
RF
Hi,
Please recommend some Huawei parameters to improve the TCH Drops & Ho failures..i need it urgently

[Cheuv]

Hi,

If the problem is over the all network it should come from something from high level.
- What core kit are you using?

- Does anything may have been change in MSC Side?

- Can you identify if that s really all BSCs of your network, or BSC attached to only one MSC (meaning other MSCs are OK)?

- No specific activities in Transmission part? Reparenting, new dimensioning?

- Also, if you say that drop and fail are at specific time of the day but not always, is there a link with traffic? Does Drop rate increase at same time than HO fail Rate?

- Are you using AMR in your Network? Also what about HR, AMR HR?

- How does GPRS is performing? Also Abn TBF Failures?

- do you observe any clear changes in HO cause distribution: ULL, DLL, ULQ, DLQ, PBGT?

- did you check if you did not lose massive amount of neighbors, like wrong manipulation at BSS level?

- What about FP, no massive changes there?


Please try to provide much of these details which may help many of us to provide you possible solution and/or answers

PS: to trace Drop Call reason, yo can also use PCHR huawei tool. There is one into the forum but unfortunately I could not work with it so you may have to request it to huawei for licence.

[parsarka]

Hi,

If the problem is over the all network it should come from something from high level.
- What core kit are you using?

- Does anything may have been change in MSC Side?

- Can you identify if that s really all BSCs of your network, or BSC attached to only one MSC (meaning other MSCs are OK)?

- No specific activities in Transmission part? Reparenting, new dimensioning?

- Also, if you say that drop and fail are at specific time of the day but not always, is there a link with traffic? Does Drop rate increase at same time than HO fail Rate?

- Are you using AMR in your Network? Also what about HR, AMR HR?

- How does GPRS is performing? Also Abn TBF Failures?

- do you observe any clear changes in HO cause distribution: ULL, DLL, ULQ, DLQ, PBGT?

- did you check if you did not lose massive amount of neighbors, like wrong manipulation at BSS level?

- What about FP, no massive changes there?


Please try to provide much of these details which may help many of us to provide you possible solution and/or answers

PS: to trace Drop Call reason, yo can also use PCHR huawei tool. There is one into the forum but unfortunately I could not work with it so you may have to request it to huawei for licence.


Many thanks for your reply(I have added reputation & thnx :) ).
Please find my remarks::
1.We are using Huawei Core.
2.There were no changes in the MSC & BSC side.
3.The day when drop increases it is found to be in all the BSCs(Drop counters have been attached.) & the day day when it reduces it gets reduced throughout & not affecting any particular BSC.
4.No activities were done anywhere in the network as confirmed by the NSS & BSS/TX teams.
5.Yes the drops increases during the network busy hour only(at 21hrs).Then gradually decreases.Also the HO failures is found to be increased but contribution is less.Majority of drops are seen due to radio link failure & T200 time out.
6.Yes we are using AMR in the network.But since the traffic utilization is only 24% there is very less AMR-HR/HR traffic.(I have attached the BS dump of 1 BSC for your reference.
7.The GPRS RTT is very high all throuhout the network.TBF failures are also high.
8.I have not checked the HO cause distribution.But the HO drop contribution is less.
9.There were no major changes in the frequency planning.

Request you to please check the same & give your suggestions as i need it urgently as I am questioned regularly by the customer.

[parsarka]

Hi,

If the problem is over the all network it should come from something from high level.
- What core kit are you using?

- Does anything may have been change in MSC Side?

- Can you identify if that s really all BSCs of your network, or BSC attached to only one MSC (meaning other MSCs are OK)?

- No specific activities in Transmission part? Reparenting, new dimensioning?

- Also, if you say that drop and fail are at specific time of the day but not always, is there a link with traffic? Does Drop rate increase at same time than HO fail Rate?

- Are you using AMR in your Network? Also what about HR, AMR HR?

- How does GPRS is performing? Also Abn TBF Failures?

- do you observe any clear changes in HO cause distribution: ULL, DLL, ULQ, DLQ, PBGT?

- did you check if you did not lose massive amount of neighbors, like wrong manipulation at BSS level?

- What about FP, no massive changes there?


Please try to provide much of these details which may help many of us to provide you possible solution and/or answers

PS: to trace Drop Call reason, yo can also use PCHR huawei tool. There is one into the forum but unfortunately I could not work with it so you may have to request it to huawei for licence.

The BSC dump has been attached for your reference of the parameter settings we are using...please reply with your suggestions

[justdream]

Do you have special promotion at your busy hour which may leads to huge increase in the traffic..

[parsarka]

No..its just natural traffic trend of this network

[RF engineer]

Many thanks for your reply(I have added reputation & thnx :) ).
Please find my remarks::
1.We are using Huawei Core.
2.There were no changes in the MSC & BSC side.
3.The day when drop increases it is found to be in all the BSCs(Drop counters have been attached.) & the day day when it reduces it gets reduced throughout & not affecting any particular BSC.
4.No activities were done anywhere in the network as confirmed by the NSS & BSS/TX teams.
5.Yes the drops increases during the network busy hour only(at 21hrs).Then gradually decreases.Also the HO failures is found to be increased but contribution is less.Majority of drops are seen due to radio link failure & T200 time out.
6.Yes we are using AMR in the network.But since the traffic utilization is only 24% there is very less AMR-HR/HR traffic.(I have attached the BS dump of 1 BSC for your reference.
7.The GPRS RTT is very high all throuhout the network.TBF failures are also high.
8.I have not checked the HO cause distribution.But the HO drop contribution is less.
9.There were no major changes in the frequency planning.

Request you to please check the same & give your suggestions as i need it urgently as I am questioned regularly by the customer.

Dear
As i checked the call drop measurement stat i see you have two problem one you have due to radio link which could be many reasons but i will summarize it as below
1- Coverage probelm
2- lack of main server
3- Handover
4- interference
5- link imbalance and link is not stable.
But you should check per cells for each reason .
And the second thing i saw you have many cells drop is high due to Hardware problem check them
Hope this help
BR
RF

[parsarka]

Hi RF Engineer,
Thanks a ton for your reply.I agree to your suggestions.
1.There is coverage problem since its a new network with coverage patches everywhere & mostly the indoor subscribers are causing the major degradations & lack of main server comes from there.
2. As for interference, we have 4.4MHz, 1800 bandwidth & our customer also has CDMA network in the same city & most of the sites are shared with existing CDMA sites.Do you suspect any interference from there??
3.As for unstable link,we have got both optical fibre & microwave media connectivity common for both CDMA & GSM network which keep fluctuating but surprisingly we dont have much alarms in the BSCs corresponding to them except for few RAI,TUAIS,AIS,CELL OUT OF SERVICE,LAPD OML alarms.Do you think the alarm sensitivity by the system is less?Also we suspect that the handover problem could be from there due to clock mismatch.what is your suggestion for this?
4.Most of the time we get TCH availability issues in many sites & find the TCH drops to have increased in them.What is suggestion on this?

5.Our VSWR threshold in the network is 1.6...so we donot get much alarms & what do suggest to track the hardware issues as our BSS team are unable to track the same.

6.Pls tell me the process & the corresponding reports in Huawei to troubleshoot the ink imbalance problem.

7.One more observation is that the drops are not constant in the cells,i.e. the cells with high drops are not repeating.So its becoming a big prblem for us to analyse.So please suggest on this too.

Hoping to get your brilliant & valuable suggestions.Thanks again

[RF engineer]

Hi RF Engineer,
Thanks a ton for your reply.I agree to your suggestions.
1.There is coverage problem since its a new network with coverage patches everywhere & mostly the indoor subscribers are causing the major degradations & lack of main server comes from there.
2. As for interference, we have 4.4MHz, 1800 bandwidth & our customer also has CDMA network in the same city & most of the sites are shared with existing CDMA sites.Do you suspect any interference from there??
3.As for unstable link,we have got both optical fibre & microwave media connectivity common for both CDMA & GSM network which keep fluctuating but surprisingly we dont have much alarms in the BSCs corresponding to them except for few RAI,TUAIS,AIS,CELL OUT OF SERVICE,LAPD OML alarms.Do you think the alarm sensitivity by the system is less?Also we suspect that the handover problem could be from there due to clock mismatch.what is your suggestion for this?
4.Most of the time we get TCH availability issues in many sites & find the TCH drops to have increased in them.What is suggestion on this?

5.Our VSWR threshold in the network is 1.6...so we donot get much alarms & what do suggest to track the hardware issues as our BSS team are unable to track the same.

6.Pls tell me the process & the corresponding reports in Huawei to troubleshoot the ink imbalance problem.

7.One more observation is that the drops are not constant in the cells,i.e. the cells with high drops are not repeating.So its becoming a big prblem for us to analyse.So please suggest on this too.

Hoping to get your brilliant & valuable suggestions.Thanks again

for link imbalance you can check http://www.finetopix.com/showthread.php?t=10569
This means you network unstable beyond your field so make the other Department involved in your problem and for the VSWR value it set to high that why you can not see the Alarm for VSWR you can ask BSS team to change this threshold in M2000 i really donot remember where it to tell .
BR
RF

[Al_G9]

Dear parsarka:
We face the same problem in our network (degradation in our KPI) and find the major reason is the external interference due to military operations, you can check the interference3-5 band on the TCH

[adriansyah]

thanks very much for your suggestions,I have added reputation to you.....the radio link drops are high in my network..please suggest some more parameter by which I can improve the drop cause due to the above reason


Already you check for link balance between DL or UL in MR. (for bad CDR and HO failure)

Cause :

- Wrong TRU Config (for BTS3012 series)
- Check radio condition
- Check HW

[osama_ali]

many thanks for your useful tools

[justdream]

Hi PARSARKA,

Have u tried to check TCH ALLOCATION STATS, to identify what TRXs causing High TCH FAILURE RATE and SDCCH FAILURE rate and etc..TA check if your site's signal is degrading correlate it with TCH alloc for TRXs causing it...Have u check your setting of Radio Link Timeout, SACCH Multiframe, T3105, there u can change the setting first if there will be improvement.
U can start from there first and if u found nothing wrong or improvement of parameter setting I gave, BSC to MSC isolation..

Pls add rep if u find it useful...if not, it's ok, badly needed...

Regards//

Expert, could you recommend me values for Radio Link timeout and SACCH Multiframe?
also, is there's a counter in huawei for Call drop due to Radio link failure?

please advice...

[fahmi]

Hi evry body,
I am doing some research for my graduation project about monitoring KPIs for 2G & 3G networks.
so I need some documents that describe these KPIs, and analysis the important KPIs for Huawei equipments (KPIs --> the most probable cause --> solutions)
thksss.

[srilasitha]

Lot of documents available in this forum. Please have a look

[mon3em]

Yup

Search ..........!!

mon3em

[evagtf@yahoo.fr]

Hi Parsarka
Have you tried to check BSC transmission Link?