Topics: Trigraph, Drop, Lac Pages: 12 (2433 words) Published: June 20, 2011

Some Relations-1- :
Some Relations-1- One BSC=6 BCSU (Base control signaling unit). One BCSU

= support 110 TRX. 1 TRX=8 time slots. Total no. of TRX = 110 *6=660 TRX

in single BSC One BSC = One LAC One BSC= 660* 8 =time slots but if dual

rate is implemented that it consider as two slots. One BSC= two Lac also

but for cityone LAC b/c it effects SD blocking and LAC updation on that

Some Relations-2- :
Some Relations-2- One BSC= 1 to 248 BCF. One BSC= 1 to 248 BTS One BTS

means = one sector of anyconfiguration One BCF means= one site of three

or four sector BCF= Base control function. BTS= Basetransceiver system.

NSEI= is hardware and software device which supports the GPRS in n/w Some Relations-3- :
Some Relations-3- One NSEI= supports 64 BTS and 128 TRX if any one of

them is full then we can assignsecond NSEI port in same BSC 1TRX=117

subscriber 1 subscriber=25 m erlangs (TCH) 1 subscriber=.004m erlangs(SD)

1 TRX=2.94 erlang(2% GOS ) 2 TRX=8.2 erlang(2% GOS ) 3 TRX=14.6 erlang(2%

GOS ) 4TRX=21.2 erlang(2% GOS ) If BSC 3VI, OSS is 4 and System is S11

then max capacity of BSC is 660TRXs. If OSS 4.2 and system S12 is using

then max capacity of BSC will be 2000TRXs
KPI’s to be monitored :
KPI’s to be monitored SD Blocking SD Drop TCH Blocking TCH Assignment TCH

Slide 6:
KPI’s to be monitored
Slide 7:
Get Service Get SDCCH Establish SD Channel Est. TCH Conn. Call Phone Ref.

Phone SD Blking SDCCHSeizer TCH Blking CSSR or TCH Assignment Call

Establishment Call completion Rate (TCH Drop call)
What is Dropped Call? :
What is Dropped Call? All cell resources are available but calls are

failing, then we have a call dropscenario. This could be caused by

software errors, congestion, C7 link failures,HW problems or many other

reasons. If a call is abnormally disconnected, a Clear Request is sent to

the MSC .If the Call is disconnectedin a normal Fashion then Clear

Message with cause code Call Control is sent. It is important to

establishwhat types of calls are failing, and over what percentage of the

network it is occurring.
SDCCH CHANNEL : SDCCH is a dedicated channel which is using for LAC

updation, Call setup, SMS inidle mode. It works in UL & DL.
SD Blocking: :
SD Blocking: SD blocking means that you are not getting SD resource for

the call origination. When MSconnects with NW then RACH and AGCH are

provided. After AGCH,SDCCH is provided but if SDCCH isnot provided at

this time due some problems or due to unavailable of SD by BSC ,it’s

called as SD Blocking.There are no of reasons for that.If such a case

arises the customer will not be able to originate any call.
Difference Between Blocking and Congestion: :
Difference Between Blocking and Congestion: It is very important to know

difference between blocking andcongestion. Some people think that both

are same, but they differ from each other. If all the SD resourcesare

full and not available for SD assign then its come into congestion. If at

a particular time call is attemptedand it fails then it known as

Reasons for SD Blocking: :
Reasons for SD Blocking: Some of them are- LAC boundary. HW Prob. Solutions for removal of SD Blocking: :
Solutions for removal of SD Blocking: Here are some steps by which we can

reduce SD Blocking- Check theNo. of SDCCH channel Available, if less then

increase SD channel taking care that there is no TCHBlocking. Check LAC

boundary, If location update is more then change the LAC of that site and

set C2 andHYS. Use of Dynamic SDCCH (It is a BSC parameter and will be

applied on whole BTS). Hardware check /shift SD to new time slot Some

times BMA and HYS parameters are useful to remove SD Blocking. Usefull Reports For SD Blocking:

Usefull Reports For SD Blocking: Use 182 to...
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