Root-Cause Analysis of Subscriber Perceived Call Set-Up Success Rate (SPCSSR)
SPCSSR shows actual performance of our network and as well as valuable customer’s perception .By
improving this KPI, we can get better quality and improve customer perception as well .All counters in
this formula show the actual picture of customer perception . Since CMPAK’s main philosophy is
“Customer Centric Approach”, this KPI becomes of utmost importance. In this case study, improvement
in overall SPCSSR of Faisalabad city(BSC150 & BSC151) is analyzed through changes in the
Number of voice
Number of Voice
Number of signaling
Number of data
Number of data
Number of signaling
C900060003 Number of SDCCH
seizure attempts for
Number of CM service
requests of MOC(Times)
[Number of CM service
requests of Emergency
Number of wireless access
due to call reestablishments(Times)
Number of MTC access
Number of SAPI3 link
establishment success on
C900060003+C900060005 Number of SDCCH seizure
of SDCCH seizure failure for
SPCSSR is dependent on two major processes.
1: TCH assignment
2: SDCCH Assignment
These KPIs show the real picture of customer perception about network accessibility.
Counter Verification With Inspur:
During the formula’s counter verification, it was found that the counter level stats are a little bit
mismatched in NetNumen & Inspur average BSC level stats. The following steps have been taken to
narrow down the discrepancies in NetNumen and Inspur:
NetNumen BSC level stats compared completely with Inspur BSC level stats.
NetNumen Cell level stats compared completely with Inpsur Cell level stats.
Counter Cell level stats of NetNumen compared with the Counter Cell level stats from Inspur.
Counter Aggregation on cell level was mismatched with BSC & Inspur SPCSSR. Reason found
out to be that aggregation for all cells is done on counter level and then put into the formula.
In order to improve SPCSSR of BSC 150 & 151 through counter level stats, firstly we started by
analyzing SDCCH assignment counter. We digged out the cells which were the major contributors in
SPCSSR degradation of the Faisalabad BSCs .The counter was [Number of SDCCH seizure failure for
assignment (Times)]. After analysis, the finding was that due high number of SDCCH Seizure failures
(operational issues), SPCSSR was degraded. Consequently, a strong follow up with FOPS team for
immediate resolution of the operational issues was ensured for improvement of customer perception.
Culprit cell sheet is attached for reference.
Secondly we digged out the SDCCH congested cells which were contributing to the degraded SPCSSR
of Faisalabad city. Addition of some time slote of SD were made to improve SPCSSR of degraded cells.
Third was the reduction of high TCH allocation failures issue at site FSB- 5686 resolved by changing
faulty E1 while there was no alarm showing on E1.
Below mentioned graph results shows a whole picture of SPCSSR trend follow up.
Faisalabad City SPCSSR
Regional improvement Trend
After Resources addition and SPCSSR improvement project on Faisalabad city .SPCSSR of
whole central is improved.
Working detailed which was done are listed below:
As a first step, cells with high SDCCH failures were identified and consequently rectified with the help
of regional FOPs to improve the SDCCH failure rate.
Secondly cells with high SDCCH Congestion were identified and worked on to relieve the SD
Congestion contributing towards SPCSSR degradation.
Third step contains multiple sub-steps
Reduction of TCH allocation failure rate
Resource addition on culprit cells.
For further improvement we will be started working on cells with lowest value of SPCSSR.
Cell selection Critera
Stats will be taken <90 % on cell level, for 15 consecutive days and one more counter will improve as a
result. After this we can achieve 1% SPCSSR of both BSCs.
SPCSSR improved significantly in Faisalabad City and on BSC Level i.e; BSC 150 and BSC 151. This
practice will be extended further towards more improvement and will be replicated in whole region,
which will enhance user experience and perception about Network.