August 8, 2011

Improve TBF Drop RateBy pcstelconext

Dinesh – 29 May 2010

Please give the list of KPI parameters for Packet data with meaning

SHELDON – 24 May 2010

Hi Krish,

 

You can calculate the average number of simultaneous TBFs per PDCH by using the

ratios: TBFPDLGPRS/PDCHDLGPRS and TBFPULGPRS/PDCHULGPRS respectively for

DL and UL. These counters are found under the object type TRAFFGPRS.

 

If the number of users per PDCH is high, then the throughput per user will be low. You

should consider adding more PDCHs if the above ratios are high.

 

Yes, the number of users per PDCH is 16 for DL and 7 for UL.

 

Paul,

 

You would experience many retransmissions when there is interference(as a result of a

poor frequency plan/allocation). However, a high retransmission rate can also be as a

result of other things, eg faulty TRX, using a static coding scheme, etc.

 

Regards,

SHELDON

Paul – 23 May 2010

Dear All,

 

According to HasnatBD, what does it mean by checking re-trasnmission rate, we can

conclude that there must be sth problem in frequency?

 

Is there any body know the relationship between retransmission and frequency

allocation?

 

Thanks,

 

Paul

krish – 22 May 2010

hi sheldon,

 

In eric thr which and how to check no of users per pdch and how it is useful?

 

I mean if i have more edge traffic then no of users per pdch are max?

 

And i think there is a limit per pdch no of users its 16 in dl and 7 in ul?k is it?

nitin – 19 May 2010

Hey , for improvement of TBF drop , check the hardware issue…….

check tbf drop due to reselection , of CS traffic, or due to no channel, or due to MS

response on up…….

u can check counter 3101,3103,3168 for improvment of tbf drop………..

afzaa – 10 May 2010

hi

can u tell me about Siemense BTS structure and its working

anand – 27 Apr 2010

please tell me the formula for calculating TBF Success Rate

Mania – 12 Apr 2010

Hi,

In response to Zeus, your problem is because Alcatel algorithm wants you to have

Pref_Mark 0 i.e least prioritized for at least one TRX if GPRS / EDGE is enabled, and

this is the TRX on which PDCHs would be allocated be it fixed or switchable.

You probably shifted PD to BCCH by changing its pref mark to 0 and

Ps_Pref_Bcch_Trx. so automatically your GSM Calls are now disfavoured for this TRX.

What you can do is to define your BCCH on the max GSM TRX count available e.g TRX-

4 if you have 4 TRXs keep all pref_marks at 0 then since alcatel uses back filling your

BCCH would be preferred for both CS and PS.

This is one way around which you can use in B-9.

Hope it proves useful

HasnatBD – 6 Apr 2010

Link adaptation is switching among the Modulation & coding schemes from 1 to 9

based on BLER(Block error rate). BLER is affected by C/I.

 

When BLER is worse the lower MCS is selected while BLER is better higher MCS is

selected.

krish – 27 Mar 2010

hi,

 

Can anyone plz explain what is link adaption in egprs?

 

 

 

 

SHELDON – 26 Mar 2010

Hi Mangesh,

 

To increase throughput, here are some of the things you should consider:

 

1. Improve C/I ( reduce interference)

2. Reduce no. of users per PDCH

3. Check PCU congestion/Utilization

 

Which vendor are you using? Also, you said you have 2PDCH per sector, what does

that mean? Are these 2PDCHs dedicated? Semi-dedicated?

 

Regards,

SHELDON

Mangesh – 26 Mar 2010

I want to know more about how to increase GPRS Speed, I am using 2 PDCH for each

sector.

HasnatBD – 22 Mar 2010

Hey,

the cause of this can be several but you can the below steps to confirm.

1. Check frequency in BBH and the retransmission rate in those cells. if high

retransmission –> for sure there is problem on Frequency

2. Try use most BCCH TRX TS for PDCH.

3. Make sure (E)GPRS link adaptation is enabled.

4. If frequency change doesn;t get good result, limit the (E)GPRS coding scheme up to

MCS7 instead of MCS9. MCS7 is more robust than MCS9.

Bijoy – 2 Dec 2009

Hi mohamed

pls explain what u want to know abt ericsson oss

 

br//

Bijoy

pankaj – 1 Dec 2009

what is TBF , and how to improve tbf DROP RATE

Pix – 8 Feb 2009

I didn’t read this question, sorry Zeus,

 

Yes, it points to a frequency problem. In RNO, can you check which TRX are carrying

most of Erlang TCH ? Also, if you’re in B10, you can check the number of PDCH

allocation per TRX (can’t you?).

 

So this could help you find out which TRX could be the problem. Are you using SFH,

BBH or NH? If SFH, then it looks like your BCCH is clean but the MA list used on the

other TRX’s is a very dirty one.

 

A popular saying: “If only my wife was as dirty as your TRX…”

TNS – 7 Feb 2009

Hi, Zeus.

 

What type of TRXs are used in this cell ( TRAG, TRAGE, … )?

Hopping enable?

 

There are two reasons ( in my opinion ): faulty TRX or bad freq…

 

( if we speak for one cell only )

 

BR

Zeus – 4 Feb 2009

Hi Pix,

 

It’s really good reading ur comments, i learned a lot from it.

btw, I have problem with the UL TBF success rate, i encountered high failure due to

radio.

There is this parameter in Alcatel to prioritize the BCCH trx (Ps_Pref_Bcch_Trx). When

i did this, there was a significant improvement, But i noticed a degradation on GSM

qos, Call drop increased also HOSR bit degraded.

 

Is there any other way on how to improved this?

 

many thanks!!!

mohamed – 27 May 2007

can you speak with me about the Ericsson OSS and it applications.

Pix – 21 May 2007

First, you must ensure the GSM QoS is good in the cell. Basically, ensure the radio

part is reliable (no interference, neighbors defined, rxlev > -85dBm at the cell border,

etc.)

 

Once this is done, it means your cell has a good GSM quality of service, but a poor

GPRS qos. So you should check that your cell is not preempting some of the PDCH to

voice calls (leading to TBF drops), or that your MFS/SGSN/GGSN are all working

correctly.

And no congestion on Ater and Gb interfaces.

 

Of course, you should put all your radio parameters regarding GPRS to their default

values. (no UL power control for instance)

 

Regards,

Pix

 

 

hey,

 

if anyone know any method to improve TBF drop, i welcome to share.

 

Thanks