- This topic has 98 replies, 1 voice, and was last updated 10 years, 7 months ago by anand.
25th August 2009 at 10:07 #52084Gerald ThomasGuest
i have a site with low traffic during busy hour but we are having SDCCH congestion from our KPIs. we had changed TRXs, checked for swap feeders and BSC configuration but the problem is still the same.
our TA=63 for all sectors and for all the sites.
please can anyone help me, i don’t what to do now.26th August 2009 at 07:26 #52085Bijoy BanerjeeGuest
What is the formula for SDCCH Blocking u r using26th August 2009 at 09:45 #52086Gerald ThomasGuest
Accessibility to SDCCH = (Number of Successful SDCCH Assignment)/(Total Number of SDCCH Attempts)27th August 2009 at 06:14 #52087BijoyGuest
Tell me when is ur Successful SDCCH Asssignment pegged?
Is it after Immediate Assignment command sent or after the Establish Indication sent from BTS to BSC?27th August 2009 at 11:12 #52088Gerald ThomasGuest
There is SDCCH Assignment Successful and SDCCH Allocation Successful. Assignment Successful is after Immediate Assignment and Allocation Successful is after Establishment Indication sent from BTS to BSC.28th August 2009 at 12:00 #52089BijoyGuest
Ok Gerald.I could have given u the exact solution,but for that i would require some more inputs,So U can Try any of these or all of these solutions one by one
1.U can Try to reduce the RACH Min. Access Threshold & RACH Busy Threshold to overcome this problem.
2.Please check if There is More LOC Update request in that cell.If there is many LOC update,u can increase the SDCCH.
3.Try remove additional SDCCH’s if any and try to put Only One SDCCH/TRX.
4.Make the BCCH TRX Lapd of 32kbps.
5.Check for Co-BSIC-BCCH,if any nearby.
7.Also check if there is Channel Activation Nack for this cell.28th August 2009 at 16:39 #52090PixGuest
few more things:
what are the values of those KPIs (failure rate and number of requests, attempts and success ?)
what is your brand of equipment ?
pix28th August 2009 at 18:12 #52091KRISHGuest
IF I HAVE SD BLOCKING 2% AND IF I INCREASE THE LAPD FROM 16 TO 32 THEN IS IT REDUCE MY SD BLOCKING?
IF I HAVE SD BLOCKING DUE TO LAC UPDATE THEN I THINK NO MEANING TO REDUCE MAX RETRANSMISSION IS IT OK?
AND CAN U EXPLAIN THISAlso check if there is Channel Activation Nack for this cell.?29th August 2009 at 05:59 #52092BijoyGuest
Only if u have high Half rate traffic,changing Lapd to 32 kbps for BCCH TRX will help.
Yes,for loc,it will not help much.Also ur immediate assignment will affect
for “Channel Activation Nack”,may i know which system r u using?30th August 2009 at 14:52 #52093krishGuest
i want to know not only bcch trx but if i will change my non hopping trx(tch trx) signalling from 16 to 64 then will it help to reduce sd blocking because my max sdcch are on tch trx?31st August 2009 at 04:37 #52094BijoyGuest
This will help only if u have high HR Traffic volume in that cell.
Also,I think there will be a limit on how many SDCCH’s can be defined on a particular TRX31st August 2009 at 09:48 #52095Gerald ThomasGuest
SDCCH failure rate is in percentage
SDCCH attempts and success are figures
Our equipment brand is ZTE31st August 2009 at 14:52 #52096krishGuest
i am not getting why u are relating half rate traffic to sdcch blocking and 64 signalling if any valid reason plz explain me?
and here i am taking example.
in our system we can define 4 sdcch per trx now suppose if i have (1) 4 trx in one cell
(2)and 16 sdcch in that cell which is max and still there is 5% sd blocking and signalling is 32k
(3)so now in this case if i will increase lapd signalling from 16 to 32 then will i get improvement in sd blocking?
plz let me know….because i want to try it and if anybody has tried it plz share………1st September 2009 at 04:27 #52097BijoyGuest
Let me explain
High HR traffic puts a high load on SDCCH Traffic bcoz it is through this SDCCH all the signalling takes place. Also as u know more HR increases the system GOS,the signalling GOS also increases.
As per your example,first put only the required no. of SDCCH which can be calculated from the MAx. SDCCH Traffic with desired GOS(i’e 0.5%) and remove all unnecessary SDCCH.It is not an intelligent practice to go on increasing the SDCCH’s in a cell to reduce SDCCH Blocking .U can also implement dynamic configurations of SDCCH
Better check the reasons for such high SDCCH Usage.If it is due to LOC update,changing Lapd from 10K to 32K will not help.
Hope u understand the point1st September 2009 at 10:40 #52098krishGuest
i think still u are not getting my point here in this case i have max sdcch and alrady we have enabled dynamic sdcch allocation.
So point is that here my sd blocking is due to lac update so will lapd from 32 to 64 will help me for reducing sd blocking?hope now u get the point.