- This topic has 61 replies, 1 voice, and was last updated 2 years, 6 months ago by sandeep harkude.
20th May 2007 at 03:48 #47347oharazuGuest
if anyone know any method to improve TBF drop, i welcome to share.
Thanks21st May 2007 at 07:18 #47348PixGuest
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)
Pix27th May 2007 at 08:26 #47349mohamedGuest
can you speak with me about the Ericsson OSS and it applications.4th February 2009 at 01:46 #47350ZeusGuest
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!!!7th February 2009 at 22:25 #47351TNSGuest
What type of TRXs are used in this cell ( TRAG, TRAGE, … )?
There are two reasons ( in my opinion ): faulty TRX or bad freq…
( if we speak for one cell only )
BR8th February 2009 at 08:39 #47352PixGuest
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…”1st December 2009 at 06:00 #47353pankajGuest
what is TBF , and how to improve tbf DROP RATE2nd December 2009 at 07:17 #47354BijoyGuest
pls explain what u want to know abt ericsson oss
Bijoy22nd March 2010 at 09:48 #47355HasnatBDGuest
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 MCS9.26th March 2010 at 03:45 #47356MangeshGuest
I want to know more about how to increase GPRS Speed, I am using 2 PDCH for each sector.26th March 2010 at 12:28 #47357SHELDONGuest
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?
SHELDON27th March 2010 at 10:43 #47358krishGuest
Can anyone plz explain what is link adaption in egprs?6th April 2010 at 08:00 #47359HasnatBDGuest
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.12th April 2010 at 07:23 #47360ManiaGuest
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 useful27th April 2010 at 05:48 #47361anandGuest
please tell me the formula for calculating TBF Success Rate