Where does TEMS INVESTIGATION fit in Design & Rollout Operation & Improvement Model Tuning Traditional OptimizationNetwork Integration Test Network Feature Optimization Initial Tuning Verification of Network Changes GPRS Performance Verification Training
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
DESIGN & ROLLOUT PHASE GPRS Performance Verification• Application Performance Test • WWW, FTP, WAP etc.• Mobility Test • Cell Reselection, RA Update
OPERATION & IMPROVEMENT PHASE Traditional Optimization • Investigate & Trouble-shooting Specific Areas • Neighbor Relation Optimization • Coverage Issues
OPERATION & IMPROVEMENT PHASE Network Feature Optimization Parameter Settings: • MS, BTS Power Control • HCS • Idle Mode Behavior • Locating Algorithm • Frequency Hopping • Intra-cell Handover
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?
TEMS Measurement & Analyzing Process ? Preparations Collect Data Analyze ReportClear objective Check equipment Save logfile Find problem Give answer areas to objectiveWhy should this Get input files Take notesmeasurement be Find solutions Prepare route Monitordone External Antenna? Changes in What should be Network changed?
Measurement Will Depend on Objective ? Preparations Possible ObjectivesClear objective Check equipment • Coverage analysisWhy should thismeasurement be Get input files • Trouble shooting Prepare routedone External antenna? • Scanning • Verify network changes
Performing Measurements withDrive Test • Large areas TEMS • Specific areasWalk TestScanning
Drive Test - Large area INPUT INPUT MEASUREMENT OUTPUTAcceptance Drive defined Plots & Report route/areaNew sites on air - Signal Strength Record LogfileFrequency Re-plan - Quality Long / Short callsBSC Re-homing Trouble Report / Assure no data loss Area for further investigation
Drive Test - Specific area INPUT Measurement OUTPUTStatistics Manipulate Trouble ReportCustomer complain - Forced handover - Identified problemLarge area drive test - Lock on to Frequency - SolutionTrouble Report - Layer 3 messages Analysis on-spot Rectify & Verify on-spot
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
Scanning INPUT Measurement OUTPUTFinding a new TEMS INV in Received SS onfrequency scanning mode different ARFCN Set ARFCN to scan plotArea NetworkScanning New frequency
Problem CasesLow Signal Strength• Interference• Handover• Call Setup Failure• Dropped Call• Misc.
Signal Strength Case TEMS INPUT Logfiles Large area DT Post-ProcessingSpecific 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
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
Signal Strength Case – Analysis Shadowed Antenna Output Power Faulty HardwareVisit site Check output power Check alarm & BTS ErrorCheck antenna installation Parameters logIs there a better antenna BSPWRT - NON BCCH FREQ Visit siteposition 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?
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.
Interference Case TEMS INPUT Logfiles Large area DT Post-Processing Specific area DT AnalysisIdentify areas with Rxqual > 5Identify source using Map and STSNew drive test around problem area?
Interference Case – Logfile analysisFrom 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.
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
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
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.
Handover Case INPUT Large area DT Post-ProcessingSpecific area DT AnalysisLook for:Repeated handover (Ping Pong)Repeated Intra-cell handoverHandover failure,Unrealistic handover
Unrealistic Handover – Reason & SolutionPossible ReasonsWrong locating settings, in Serving or Target cellNote: Could be on purpose e.g. Dual Band network with HCSSolution• Fix locating settings e.g. MSRXSUFF, BSRXSUFF
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)
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.
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.
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,
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
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.
Failed Call Setup (Blocked Call) Example Multiple Channel Requests. Successful Random Access after the third try. Congestion in SDCCH.
Dropped Call Case - Input• Statistics Report• Note from drive test.
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!!!
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).
Miscellaneous Case 1From 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. -75dBmAnalysis• Since DL SS & Rxqual is goodSuspect UL problems e.g. external uplink interferenceConclusionTMA power turned off
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 TCHCHG1 SDCCH8 BCCHCHG0 TCH TCH TCH TCH TCH TCH SEKTOR B
Miscellaneous Case 3From TEMS Logfile• Fail to perform Call SetupAnalysis• 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 properlydefined in MCS and LAConclusion• Corrupted block in MSC
. Cell Reselection Sample ReportRouting 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!