3. Where does TEMS
INVESTIGATION fit in
Design & Rollout Operation & Improvement
Model Tuning Traditional Optimization
Network Integration Test Network Feature Optimization
Initial Tuning
Verification of Network Changes
GPRS Performance
Verification
Training
4. DESIGN & ROLLOUT PHASE
Network Integration Test
When a site is integrated to BSC it is tested
• Call set up test
• Timeslot test, forced call test
* TEMS Pocket is the preferred tool for Network Integration Test
6. DESIGN & ROLLOUT PHASE
GPRS Performance Verification
• Application Performance Test
• WWW, FTP, WAP etc.
• Mobility Test
• Cell Reselection, RA Update
7. OPERATION & IMPROVEMENT
PHASE
Traditional Optimization
• Investigate & Trouble-shooting Specific Areas
• Neighbor Relation Optimization
• Coverage Issues
8. OPERATION & IMPROVEMENT
PHASE
Network Feature Optimization
Parameter Settings:
• MS, BTS Power Control
• HCS
• Idle Mode Behavior
• Locating Algorithm
• Frequency Hopping
• Intra-cell Handover
9. OPERATION & IMPROVEMENT
PHASE
Verification of Network Changes
Did a certain change in the network give desired results?
• New coverage area?
• Less interference?
• Better speech quality?
• Is handover possible?
10. TEMS Measurement & Analyzing
Process
? Preparations Collect Data Analyze Report
Clear objective Check equipment Save logfile Find problem Give answer
areas to objective
Why should this Get input files Take notes
measurement be Find solutions
Prepare route Monitor
done
External Antenna?
Changes in What should be
Network changed?
11. Measurement Will Depend on
Objective
? Preparations
Possible Objectives
Clear objective Check equipment • Coverage analysis
Why should this
measurement be
Get input files
• Trouble shooting
Prepare route
done
External antenna? • Scanning
• Verify network changes
13. Drive Test
- Large area
INPUT
INPUT MEASUREMENT OUTPUT
Acceptance Drive defined Plots & Report
route/area
New sites on air - Signal Strength
Record Logfile
Frequency Re-plan - Quality
Long / Short calls
BSC Re-homing Trouble Report /
Assure no data loss
Area for further
investigation
14. Drive Test
- Specific area
INPUT Measurement OUTPUT
Statistics Manipulate Trouble Report
Customer complain - Forced handover - Identified problem
Large area drive test - Lock on to Frequency - Solution
Trouble Report - Layer 3 messages
Analysis on-spot
Rectify & Verify on-spot
15. Walk Test
INPUT Measurement OUTPUT
Statistics Add file marks (GPS) Trouble Report
Customer complain Scanning Planning Report
Micro cell planning - Antenna location
Indoor cell planning - Frequency
- HCS setting
* TEMS Light is the preferred tool for indoor cell planning
16. Scanning
INPUT Measurement OUTPUT
Finding a new TEMS INV in Received SS on
frequency scanning mode different ARFCN
Set ARFCN to scan plot
Area Network
Scanning New frequency
19. Problem Cases
Low Signal Strength
• Interference
• Handover
• Call Setup Failure
• Dropped Call
• Misc.
20. Signal Strength Case
TEMS
INPUT Logfiles
Large area DT Post-Processing
Specific area DT Analysis
• Identify areas with low signal strength e.g. SS < -100dBm (outdoor)
• Look at RxLev distribution (for acceptance)
• Compare with design level or new requirements
21. Signal Strength Case
– Possible Reasons
• Shadowed Antenna
• Antenna Direction
• Antenna Height / down tilt
• Output Power
• Missing Neighbor Relation
• Site Location
• Faulty Hardware e.g. antenna & TMA
• Cell is down
22. Signal Strength Case
– Analysis
Shadowed Antenna Output Power Faulty Hardware
Visit site Check output power Check alarm & BTS Error
Check antenna installation Parameters log
Is there a better antenna BSPWRT - NON BCCH FREQ Visit site
position at same site? BSPWRB - BCCH FREQ
Height/down Tilt Missing Neighbor Site Location
Add reduce down tilt? Is the call dragged? Possible to move site?
Can antenna be placed Is low SS due to missing New antenna location at
lower or higher to give neighbor relations same site? Is it necessary
better coverage? to expand and build a new
site?
23. Signal Strength Case
– Possible Solutions
• Change parameter BSPWR , BSPWRT.
• Add neighbor relation.
• Physical changes:
• Antenna direction
• Antenna height, tilt or position
• New site as last option.
24. Interference Case
TEMS
INPUT Logfiles
Large area DT Post-Processing
Specific area DT Analysis
Identify areas with Rxqual > 5
Identify source using Map and STS
New drive test around problem area?
25. Interference Case
– Logfile analysis
From logfile & map:
What channel group suffer from interference? HOP or Non HOP?
• Check Current channel information in TEMS INV, hopping
channel and hopping frequency.
Where does the interference come from? Cell name?
• Study map and logfile, look for co-channel or adjacent channel
interference.
Does the interference lead to lower SQI?
• Look at SQI measurement during high RxQual.
Use STS & RNO to assist analysis.
26. Types of Interference
• Co - Channel interference
• Adjacent Interference
BCCH 600 CASE 1
BCCH 595
CASE 2 High site
BCCH 590
BCCH 590
BCCH 590
BCCH 590
27. Interference Case
– Possible Reasons
• Poor frequency plan
• No dominant cell --> low C/I ---> increased Rxqual
• Frequency Hopping is off
• External interference e.g. jammer
Example of high Rxqual
due to low Signal Strength
28. Interference Case
– Possible solutions
• Enable Frequency Hopping or add frequencies to Hopping
group.
• Enable BTS Power Control, MS power control and make it less
aggressive.
• Change frequency of interferer or interfered cell:
– Possible to find new frequency by using TEMS Scanning.
• Down tilt or change antenna of interferer.
• Redo frequency plan.
• Add new site.
29. Handover Case
INPUT
Large area DT Post-Processing
Specific area DT Analysis
Look for:
Repeated handover (Ping Pong)
Repeated Intra-cell handover
Handover failure,
Unrealistic handover
32. Repeated Handover (Ping Pong)
- Possible Reason 2
• Offset only in one direction e.g A-B for Inter
BSC relation
BSC 1 BSC 2
BSC BSC
CELL A CELL B
A -> B OFFSET = -5dB No B -> A OFFSET
33. Repeated Handover (Ping Pong)
– Other Possible Reasons
No dominant Server
• No dominant server
• Locating penalty settings
e.g. PSSBQ, PTIMBQ
• Too small hysterisis
setting
34. Repeated Handover (Ping Pong)
– Possible Solutions
Antenna direction
Antenna Tilts
Plan for new site
Change Locating Parameter e.g.
KHYST or LHYST
35. Repeated Handover (Ping Pong)
– Possible Solution
Change Parameter, KHYST or LHYST
Hysterisis
CELL A CELL B
Handover
From A to B
37. Handover Reversion
– Common Reason
Duplicates of BSIC BCCH combinations in neighboring list
Handover command?
BSC
610_12
606_33
610_31 610_31
Serving cell
Neighbor cell 2
Neighbor cell 1
608_32
608_32
Road
38. Handover Reversion
– Other Reasons
Uplink interference in target cell
Downlink interference at MS
Solutions
Interference Investigation
• MRR
• Statistics
• Scanning
39. Handover Case
– Repeated Intra-cell Handover
Possible Reasons
Wrong intra-cell handover settings
External Uplink Interference
Possible Solutions
Consider to change parameters:
• SSOFFSETUL, SSOFFSETDL
• QOFFSETUL, QOFFSETDL
A wrong setting of parameters will cause “unnecessary” IHO
Turn off Intra-cell Handover?
41. Unrealistic Handover
– Reason & Solution
Possible Reasons
Wrong locating settings, in Serving or Target cell
Note: Could be on purpose e.g. Dual Band network with HCS
Solution
• Fix locating settings e.g. MSRXSUFF, BSRXSUFF
44. Call Setup Failure
– Input Activities, Troubleshooting
Input Activities
Measurement Type
•Small Area Drive Test
Initial Tuning •Lock on problem cell’s BCCH
(Acceptance Test) •Force handover to the cell
Troubleshooting Post-Processing Output
(Customer •Geographical Report (if
complaint etc.) necessary)
45. Call Setup Failure Analysis
- Initial Tuning Scenario
• Check the TEMS statistics report (Blocked Call)
if there is Call Setup Failure.
• If yes, identify the problem cells and which
logfile from geographical report.
• Replay the logfile and jump to the Blocked Call
event.
• Check if there is any successful call setup to the
problem cell.
46. Call Setup Failure Analysis
- Initial Tuning Scenario cont.
• Review the layer 3 messages to check at which
sequence the failure occur (random access,
SDCCH, TCH assignment etc.).
• Check STS report on the problem cell. Is there
any traffic (SDCCH & TCH) in the cell, SDCCH
& TCH seizures, congestion etc.
• Check fault report & CDD configuration.
47. Call Setup Failure Analysis
- Troubleshooting Scenario
• Before performing drive test, check STS report &
fault report.
• If can not identify the problem, perform drive
test.
• During measurement, lock the BCCH of the
problem cell.
• Review the layer 3 messages to check at which
sequence the failure occur (random access,
48. Call Setup Failure Analysis
- Possible reasons with ranking
• Low Signal Strength
• Interference
• High Congestion on SDCCH
• High Congestion on TCH
• Transmission Fault
• Faulty TRU/Hardware
• Central Processor Overload
• Software File Congestion
49. Call Setup Failure Analysis
- Possible solutions
• Low signal strength Signal strength analysis.
• Interference Interference analysis.
• High Congestion on SDCCH:
Define more SDCCHs.
Activate adaptive configuration of logical channel
feature and immediate assignment to TCH.
• High Congestion on TCH:
Add capacity/Tune coverage array.
Activate assignment to worse cell.
50. Failed Call Setup (Blocked Call)
Example
Multiple Channel Requests.
Successful Random Access after the
third try.
Congestion in SDCCH.
51. Dropped Call Case
- Input
• Statistics Report
• Note from drive test.
52. Dropped Call Case
- Analysis
• From plot, identify which & where in logfile
the dropped call occurs.
• In the log file, Jump the drop call event.
• Check if there is a disrupt in the recording. If
yes could be a false drop due to TEMS
mobile disconnection during recording!!!
53. Dropped Call Case
- Analysis (cont)
• Check the Radio environment just before drop:
– If High Rxqual for a longer period of time and RLINKT expire Interference
problem.
– If Low SS DL, SSDL < MSSENS ( -104dBm) low signal strength problem.
– If TA > 63 too far from the cell.
• If DL radio is good, check the TX power. If there is MS power down regulation when
the MS is close to the cell. If full power suspect uplink interference or antenna,
TMA problem.
• Verify or isolate the problem using STS (Drop call and reasons).
54. Miscellaneous Case 1
From TEMS Logfile
• Good Signal strength DL, Good Rxqual DL
• No call set up possible unless very close to site = high SS
• Dropped call when SS < approx. -75dBm
Analysis
• Since DL SS & Rxqual is good
Suspect UL problems e.g. external uplink interference
Conclusion
TMA power turned off
55. Miscellaneous Case 2
From TEMS Logfile
• TCH has lower Signal strength than BCCH (Own BCCH included in
BA-list)
• BTS power control = OFF
Conclusion
Antenna cable for TCH is swapped between sectors (CDU-A)
SEKTOR C
Configuration/cell
SEKTOR A
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
CHG1
SDCCH8
BCCH
CHG0
TCH
TCH
TCH
TCH
TCH
TCH
SEKTOR B
56. Miscellaneous Case 3
From TEMS Logfile
• Fail to perform Call Setup
Analysis
• Check if any success call setup to the same cell No
• Check if handover is possible Yes
• Suspected wrong cell definition in MSC but Cell is properly
defined in MCS and LA
Conclusion
• Corrupted block in MSC
61. Cell Reselection Prediction
• Dedicated mode drive
test
HO types
LA HO (10)
HO int. (220)
LA HO at BQ (1)
HO int. at BQ (11)
BSC3 serving
Other BSC
62. Cell Reselection Prediction
• BCCH Scanning
• Simulate the cell update with different CRH
values CRH = 4 dB CRH = 8 dB
CRH # HO
0 365
2 246
4 211
6 178
8 156
10 147
12 138
14 130
63. GPRS Field Measurement
- Procedure
Set up files
? Preparations Cell definitions
TEMS,
IP Sniffers GIMS
…
Excel
Mapinfo Dig maps
Charts / Tables Graphical
presentation of route
Report
64. GPRS Field Measurement
- Type of Measurements
• Application Performance Test
– Ping
– WWW
– FTP
– WAP
• Mobility Performance Investigation
– Cell Reselection
– RA Update
66. GPRS Application Test Tools
• General
– Windump, Commview, Ethereal, Protocol Analyser
for Gb
• PING
– MS DOS ping command
• WWW
– IE, Netscape
• FTP
– DOS FTP, WS_FTP, TEMS built in sequence
67. GPRS Field Measurement
- Mobility Performance
Investigation
• Number of Cell Reselection & RA Update
• TCP Outage Time
• Cell Reselection Failure
69. .
Cell Reselection Sample Report
Routing Area Time Cell Target Reselection Result Comments
Cell time
BSC1 16:30:42 D0241A D0241C 2s OK NA
BSC1 16:33:18 D0241B D0242A 2s OK NA
BSC1 16:35:04 D0242A D0248C 21 s OK This cell reselection was
made to a cell located quite
far away (not the closest),
thus the RxLev was quite
bad!
BSC1 16:37:44 D0244B D0248C -- NA No throughput before or
after the cell reselection.
This is due to that the cell
DF0242B were halted by
some reason!
BSC1 16:38:11 D0248C D0244B -- Failed The through put was never
resumed and the FTP
connection was aborted by
the ftp-server!
