- This topic has 17 replies, 1 voice, and was last updated 11 years, 11 months ago by Iwan.
9th October 2008 at 08:23 #54092EugeZGuest
I seem to have a lot of cells with HIGH SDCCH drops leading to Low CSSR.
Kindly advise me what i should do to reduce this.9th October 2008 at 11:47 #54093pixGuest
we talked about this a lot in this forum already.
check HW status (exchange TRX, check path balance, …), interference, coverage, or perhaps some problems of authentication or ciphering during the SDCCH phase (core network issues, involving MSC or HLR)
Pix10th October 2008 at 07:28 #54094EugeZGuest
I think i missed your earlier discussionon this issue.
My understading is that SDCCH drops are caused by poor RXQUAL, TA,signal strength, & Hardware.
From the business objects tool most cells have SDCCH drops due to other reasons.
This includes hardware. what kind of checks do we need to do to this hardware in order to solve the problem?5th December 2008 at 03:08 #54095SAGuest
I think that you work with an Ericsson network so I would base my answer on that.
There are 2 known formulas for the SDCCH Drop:
The second formula corresponds to the TCH Congestion excluded. So, the first formula really goes off the limit when there is congestion.
The reason counters are the following:
CDISTA: Excessive TA, that is if the TA value at a dropped connection is higher than or equal to the cell parameter TALIM.
CDISSS: Low signal strength in downlink and/or uplink per cell (CDISSS or CDISSSSUB), that is if the signal strength is less than the BSC exchange properties LOWSSUL and LOWSSDL in uplink or downlink respectively, or in both the uplink and downlink.
CDISQA: Bad quality in downlink and/or uplink (CDISQA or CDISQASUB), that is if the radio link quality is less than the BSC exchange properties BADQUL and BADQDL in uplink or downlink respectively, or in both the uplink and downlink.
As you can see the Reasons also depend on the parameter configuration of the TALIM, LOWSSDL, LOWSSUL, BADQDL and BADQUL. Maybe you can check the values and consider to move a couple of them and after check the new distribution.
You are right. The Other reason is normally around 70% – 75% in the Ericsson networks that I have seen.
The SDCCH Drop can be improved by:
– Adjusting the LA border so the interaction is minimum.
– Using parameters such as the ACCMIN, CCHPWR and/or MAXTA. But be careful with the coverage and some complaints.
– Better antenna performance. Remember to use electrical tilt (if possible) instead of too much mechanical.
– In you have a MSC in Pool and High SDCCH Drop check if there is any issue with the synchrony.
– I turned off the SDCCH HO (SCHO) and it worked in some sectors. Maybe you can try that.
SA26th January 2009 at 23:34 #54096S. OLSENGuest
SDCCH Drops Ericsson:
Does anyone have a breakdown for the specific reasons for Ericsson SDCCH drops due to ‘OTHER’?
It is well known T200 time out is one of the events to trigger? Any others?5th February 2009 at 11:02 #54097MUIDEENGuest
causes of TCH congestion25th March 2009 at 10:50 #54098Mr.DavidGuest
Bad Transmission due to weather18th September 2009 at 14:01 #54099PuneetGuest
I seem to have a lot of cells with HIGH TCH drops by the reason of uplink Bad Quality and Suddenly drop in Ericsson.
Kindly advise me what i should do to reduce this uplink Bad Quality and sudden drop on the cells?19th September 2009 at 07:07 #54100BijoyGuest
UL Bad quality-check for CDMA/external interference/Hardware issues
Sudden drop-check for coverge & HO issues first.20th January 2010 at 13:48 #54101SDCCH Drop Signal StrengthGuest
SDCCH Drop Signal Strength21st January 2010 at 10:55 #54102T-MaxGuest
Could you help me what are the parameters to take care if we have low PSR(Paging success rate) & LU(Location Update)on Siemens and Huawei network? even we have already done some adjustment on LA boundary and checked that one LAC is only for one BSC ; and no cell have same couple BSIC/BCCH.
Thank’s in advance for your collaboration.
T-Max10th February 2010 at 12:33 #54103naquash ahmedGuest
In huawei, we can achieve good PSR by adjusting the parameter “Rach min access level”.10th February 2010 at 12:54 #54104JeffGuest
Hi naquash ahmed,
How do you improve Paging Success Rate by tuning RACH Min.Access Level??
Need some help here.14th February 2010 at 15:07 #54105safarGuest
hi ahmed ‘
Is it really by tunning rach min acc have improved sd drop in ur network?plz explain its interesting…19th March 2010 at 04:53 #54106senthil kumar.KGuest
How blank call issuse/ call drop occurs in particular site are area.
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