- This topic has 16 replies, 1 voice, and was last updated 13 years, 5 months ago by Fedie.
22nd May 2007 at 07:42 #47425A. QadahGuest
I am a Motorola RF planning and optimization engineer, i come across High SDCCH RF loss rate problem; i was wonderin if anyone have moe information, experience in solvin such matter? it could be caused by hardware/ or interference/ anyone knows how to minimize this problem? especiallt at border cells (internation borders, not lac borders)
thank you22nd May 2007 at 08:10 #47426PixGuest
Hello A. Qadah,
At international borders, you must get a lot of interferences from other operators, since there is usually no agreement on which frequencies belong to whom.
Therefore, in order to reduce interferences without knowing interfering frequencies, you must use synthetized frequency hopping, with as many frequencies as possible in each FHS. This way, it should average as much as possible all possible interference without too much work.
Keep in mind that the BCCH TRX will use a non-hopping frequency, so place your SDCCH timeslots on hopping TRXs.
If you’re experiencing hardware failures, or if there is no interference in this area, you must perform further investigations.
Finally, you may experience SDCCH congestion rate (due to high number of imsi attach / imsi detach caused by roaming ?) but it is not the same as sdcch drop rate.
Pix22nd May 2007 at 12:00 #47427TomarGuest
My opinion is, that to place SDCCH to NonBCCCH is not very good solution. In case of TRX outage, you can’t to make any SDCCH transaction (setup call, SMS, LAC update…).
BR Tomar22nd May 2007 at 16:34 #47428PixGuest
Yes, i forgot about that. Actually what i used to do is to place a SDCCH on a non bcch trx as well as one on the bcch trx. And by default, SDCCH traffic goes in priority to the last TRX’s SDCCH.
By the way, as far as i remember, it is forbidden not to put a SDCCH on BCCH TRX in alcatel systems.25th May 2007 at 20:40 #47429somethingGuest
if its an ericsson system..you can use ACLC feature…automatic configuration of logical channels26th May 2007 at 07:47 #47430Rishabh NathGuest
I am working on Nokia GSM system. At some sites even if subscriber is in good coverage , the calling party gets “switched off or not reachable” announcement. Can anyone suggest a solution ?26th May 2007 at 12:07 #47431PixGuest
It means that the “called party” is already IMSI DETACHed. Basically, it means the MS didn’t send a LOCATION UPDATE message to the network, or that the network failed to decode it. Therefore the network assumes the MS is detached.
Check that the timer controlling the periodic location update is correctly set (is it the timer T1202 ?? i’m not sure), try to reduce it to 3 hrs or 4 hrs.
There is also a timer at BSC or NSS side, telling how long the NSS should wait without getting a LU message from a MS before deciding it is detached.. check this timer (timers ?) as well. Check 3GPP, it’s all described in there.
Regards,26th May 2007 at 12:54 #47432TufailGuest
there is problem in PCH dimensioning increase ur paging capacity.\
this wil resolve the issue.
tufail26th May 2007 at 14:34 #47433DanishGuest
Kindly check for the lossses in Uplink and Dowlink after ensuring Configuration issue and Paging Performance
Danish26th May 2007 at 20:17 #47434adeelGuest
location update timer is T3212, i think.26th May 2007 at 20:51 #47435pixGuest
yes, t3212, thanks 🙂1st June 2007 at 14:52 #47436FedieGuest
Can someone assist me on selection procedures for SDCCH/8 or SDCCH/4 signalling channels.3rd June 2007 at 05:24 #47437NaushadGuest
PLZ. U CHECK RF FEEDER CABLE SWAPPING4th June 2007 at 17:27 #47438TomarGuest
selection of SDCCH/8 or SDCCH/4 signalling channels depending on behavior of your subscribers.
Moustly SDCCH/4 could be enought for 1 TRX cell. Moustly SDCCH/8 could be enought for 2 and 3 TRX cell. Moustly 2xSDCCH/8 could be enought for 4 TRX cell. But in special cases you must add the next SDCCH due to blocking (LAC border, social event complex..). Very usefull if feature caled as TCH/SDCCH channel. Check yor SDCCH blocking from counters. If you have blocking for particular cell > 1% (or 2 or 5 – depends up to you) then add SDCCH to this cell.24th June 2007 at 19:16 #47439akefaGuest
what is trx outage ?