unspecified call drop - test case 2012
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04/11/2023
Sudden Unspecified Call Drop Analysis
In building Site
INDOORGSM & WCDMA COVERAGE TEST
Objective:
To locate and investigate the cause of several sudden dropped calls made by NEMO Handy Smartphone under good Radio Condition in 28th Floor of OPERATOR A House
TEST CASE SCENARIO
Test Cases
26th November 2012
Spot test (static)on each floor:
4 locations on each floor
Round 1: Short Call (Lock 2G)
Round 2: Short Call (Dual Mode)
UE Model
Nemo Handy-HTC Vivid (Smart Phone-Android)
PROBLEM DESCRIPTION: Floor Map (Spot Test)
The above floor plan was used during this walk test procedure and the test was conducted on floor:1- Floor 28
IBC Antenna Location
ROUTE
P1
P2P3
P4CHAM
CHU
RI S
QU
ARE
CU
Rama IV Rd
SPOT TEST RESULTS 3G
IMSI Number: 520189305380760Test Place: 28th Floor
Test Number Test Point Call Attempt Call Success Call Drop Call Block
0816120012
P1 10 9 1 0
P2 10 5 5 0
P3 10 5 5 0
P4 10 5 5 0
181
P1 9 9 0 0
P2 10 9 1 0
P3 10 10 0 0
P4 10 10 0 0
MTM P4 5 5 0 0
Result Analysis – Call Drop 1FLOOR 28 – UMTS – 0816120012
•The signal level at this floor are good. There has no pilot pollution or poor coverage in this point. However, there have a lots of call drop happen during spot test at this floor. • The call drop reason are due to normal, unspecified reason.
Result Analysis – Call Drop 2FLOOR 28 – UMTS – 0816120012
•The signal level at this floor are good. There has no pilot pollution or poor coverage in this point. However, there have a lots of call drop happen during spot test at this floor. • The call drop reason are due to normal, unspecified reason.
Result Analysis – Call Drop 3FLOOR 28 – UMTS – 0816120012
•The signal level at this floor are good. There has no pilot pollution or poor coverage in this point. However, there have a lots of call drop happen during spot test at this floor. • The call drop reason are due to normal, unspecified reason.
Result Analysis – Call Drop 1FLOOR 28 – UMTS – 181
•The signal level at this floor are good. There has no pilot pollution or poor coverage in this level. However, there have a lots of call drop happen during spot test at this floor. • The call drop reason are due to switching equipment congestion – indicates that the switching equipment generating this cause is experiencing a period of high traffic.
CALL TRACING ANALYSIS (1/3)
SYSTEM RELEASE NORMAL RELEASE
RNSNK01 MSSRST2-3G
RNSNK01 MSSRST2-3G
RNC 3G MSC RNC 3G MSC
+0.000s ►
+0.000s ►
MM-DMTAP | CM service request MM-DMTAP | CM
service request
+0.019s ◄
+0.009s ◄
SCCP_ITU | Connection Confirm SCCP_ITU |
Connection Confirm
+0.019s
◄
+0.018s
◄
RANAP | initiatingMessage |
id-LocationReportingC
ontrol
RANAP | initiatingMessage |
id-LocationReportingC
ontrol
+0.033s
◄
+0.018s
◄
RANAP |
initiatingMessage | id-CommonID
RANAP |
initiatingMessage | id-CommonID
+0.033s
◄
+0.018s
◄
RANAP | initiatingMessage |
id-SecurityModeContr
ol
RANAP | initiatingMessage |
id-SecurityModeContr
ol
+0.871s
►
+0.140s
►
RANAP | successfulOutcome
| id-SecurityModeContr
ol
RANAP | successfulOutcome
| id-SecurityModeContr
ol
+0.882s ◄
+0.143s ◄
MM-DMTAP | Identity request MM-DMTAP |
Identity request
+0.979s ►
+0.248s ►
CC-DMTAP | Setup CC-DMTAP | Setup
+0.992s ►
+0.260s ►
MM-DMTAP | Identity response MM-DMTAP |
Identity response
The comparisons between SYSTEM to NORMAL RELEASE for the above calls tracing:
CALL TRACING ANALYSIS (2/3)
+1.002s ◄
+0.264s ◄
CC-DMTAP | Call proceeding CC-DMTAP | Call
proceeding
+1.097s
◄
+0.419s
◄
RANAP |
initiatingMessage | id-RAB-Assignment
RANAP |
initiatingMessage | id-RAB-Assignment
+3.592s ►
+1.000s ►
RANAP | outcome | id-RAB-Assignment RANAP | outcome | id-
RAB-Assignment
+3.599s ◄
+1.548s ◄
CC-DMTAP | Progress CC-DMTAP | Progress
+3.609s ◄
+1.609s ◄
SUPS | Invoke CC-DMTAP | Connect
+3.609s ◄
+1.800s ►
CC-DMTAP | Alerting CC-DMTAP | Connect acknowledge
+3.609s ◄
+120.949s ►
CC-DMTAP | Connect SCCP_ITU | Inactivity Test
+4.159s ►
+124.929s ◄
CC-DMTAP | Connect acknowledge SCCP_ITU | Inactivity
Test
+21.758s
◄
+168.360s
►
CC-DMTAP | Disconnect
| 31 Normal, unspecified
CC-DMTAP | Disconnect
| 16 Normal call clearing
+22.959s
►
+168.366s
◄
CC-DMTAP | Release | 31 Normal, unspecified CC-DMTAP | Release |
16 Normal call clearing
+22.963s
◄
+168.601s
►
CC-DMTAP | Release
complete | 31 Normal, unspecified
CC-DMTAP | Release
complete | 16 Normal call clearing
+22.963s
◄
+168.617s
◄
RANAP | initiatingMessage | id-Iu-Release | 83 normal-
release
RANAP | initiatingMessage | id-Iu-Release | 83 normal-
release
+24.399s
►
+176.709s
►
RANAP |
successfulOutcome | id-Iu-Release
RANAP |
successfulOutcome | id-Iu-Release
+24.450s
◄
+176.759s
◄
RANAP |
initiatingMessage | 3 SCCP user originated
RANAP |
initiatingMessage | 3 SCCP user originated
+24.452s ►
+176.761s ►
SCCP_ITU | Release Complete SCCP_ITU | Release
Complete
CALL TRACING ANALYSIS (3/3)
RANAP | outcome | id-RAB-Assignment
RANAP | initiating | id-RAB-Assignment
CC-DMTAP | Progress
CC-DMTAP | Connect
CC-DMTAP | Connect acknowledge
SCCP_ITU | Inactivity Test
CC-DMTAP | Disconnect | 16 Normal call clearing
SUPS | Invoke
CC-DMTAP | AlertingCC-DMTAP | Connect
RANAP | outcome | id-RAB-Assignment
RANAP | initiating | id-RAB-Assignment
CC-DMTAP | Progress
1. Through the call tracing analysis it is clearly seen that the call flow for SYSTEM RELEASE – Cause Code 31 Normal Unspecified showed no response from RNSNK01 to MSSRST2-3G MSC leading to the SUPS- INVOKE Signal sent from MSSRST2 to RNSNK01 again
2. The possibility for having routing table on MSSRST2 needs to be further check as the calls were made under very good radio condition
Summary & Recommendation
. 1. The complains of having frequent call drops were initiated from OPERATOR A House at floor 28
2. Further analysis has showed that the radio condition of which the calls were made were GOOD; i.e. RSCP -50’s dBm or better and EcNo -5’s dB
3. Core’s Tracing analysis has demonstrated the abnormal call flow where the RNC did not send the response upon the receipt CC-DMTAP | Progress from MSC
4. Since no response yet from RNC, the MSC sent the Invoke CC DMTAP signal to RNC 5. The call duration was various from 30 seconds up to 2 minutes before DROP occurred6. Further investigation needs to be done on RNSNK01 – MSSRST2 to see some possible
errors of routing table or faults
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