Silence Problem

To Abdel

1)The call mute can be because of Interference.
2)Poor RX_LEVEL
3)BAD transmission

Regards
Madhu

Hi,

This is a very comman problem. It’s ‘coz of multiple reasons. See any call is basically a circuit or channel. I.e:
Call(Circuit made of this call) =

TRX-TS,KSW-TS,GPROC-TS,TS-on the E1 port at site ==> TS-E1 port at BSC –> ksw-TS-> TS at E1 port going towards transcoder ==> ts- e1 transcoder-> KSW-TS ==> MSC E1 Pool (physical cables).

[
TS = time slot / channel of trx or ksw or gproc or E1 link.

gproc= proccessor at site,bsc,xcdr.

ksw= kilo port switch== multiplexer high way, distributing the ch/TS to/from E1 port to their correct destination(tS/CH on E1 port, trx, gproc .). It is inside site, BSC, transcoder.

E1= 32(30) 64kbps channels (=2Mbps) port. It is a serial to parallel – wise versa converter.

]

So problem could be at any of these parts of the complete circuit.

CIRCUIT = RCI + CIC

RCI= trx-ts,site e1 etc. radio part.
CIC= bsc to msc via trascoder.

But generally you find problems in :-

1) Hardware problem at site-bts.
OR
2) E1 link(32 chs/ TS) cross connection at any of these interface.

1:- Hardware problem:- E.g: In motorola system, we get RCI Alarms for one/more TS of one/more TRX. This indicates us that we have “mute” problem. The problem could be at any of above.
But we try to reset the trx.
If multiple such alarm comes, & if there is a common factor , e.g a common E1 link(port), we try to reset this MMS(MSI) -E1 port.
This may clear the ALARM; BUT wait if the alarm reccurs(i.e. when the same circuit being used again), means the problem still exists.

If by analysis we are pretty sure we try to replace the faulty dev(trx or e1-port).

2:- TRANSMISSION GUY PROBLEM:- The links(E1-32 chns) might have been cross-connected, means- call-circuit of one goes to other. This’s totally meaning less hence no-audio problem.

Confirm which is the ch/ts of which E1. Ask the transmission team to check at these interfaces. Site-ddf, bsc-ddf, msc-ddf. DDF=distribition frame(like cable hub- a mess!).

You can Also do drive test of the area to confirm the cells, trx, cics with this problem.

Also you can enable call-trace (CTP) on the affected area(during busy hour), hoping you capture the faulty circuit.
!!But one warning if you enable a BSC-Level trace for say 1/2 hour without setting maximum calls, a BSC may be making more than 5000 calls per half hour. Associated ctp huge data transfer&proccessing from BSC -TO-OMC, might make the BSP(Master proceessor at BSC utilised 100%) -ineffect loading the BSC & STATS not coming in the OMC. Or worse BSC proccessor getting reset= BSC getting reset ===> YOU ARE FIRED.

But cell level trace are harmless, even for bsc-level trace set the max calls at

Hi guys,
There is no CIC problem at all, I thought CIC can cause one way communications, I saw this before, the problem i have got here is in my network, you call somebody then may be you chat for seconds and then silence will start, if you wait you can hear his voice again or silence will continue, based on my experience i don’t think this is a CIC problem.
This problem usually happens in our largest city. We have got a lot of adjacent frequancies not the BCCH but a lot of adjacent TCH frequancies, Therefore can this be the cause?

which components of the BSC communicate with those of the BTS.

Hi Abdel,
mostly silence call/blank voice was due to transmsion problem not in radio part and defined as normal call.
if the problem occured due to transmisiion problem, try to conduct verticality check in Abis and Ater. check every single port/slots which have problem. u can query and localize problem from BSC log in ftp data.
after u do it, u can localize which port or slot which have problem, then do troubleshooting with instalation team…

might help.

There is a very poor possibility, Do you use VAD service? how much AF has been considered in ur net(Activity Factor in your network)- If handover and interference is ok mean Radio ok , if you have problem in all bss the problem can be related to Core too.

Hi Abdel

There are so many co BSIC-BCCH in neighbors list.Pls check the problem after removing the co BSIC-BCCH