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Training_DriveTest & Optimization

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Training_DriveTest & Optimization Powered By Docstoc
					   Main Tools for Radio Network
        Optimization GSM
  Statistic Handling Tool    NWS (C); SPOS&Turle, Statics (I)

   OSS Recording Tool        PMR, RNO package (C)

  Cell Data Design Tools     CNA (C); IPOS, BSSTool (I)

    Field Measurement        TEMS only!!!

Field Measurement Analysis   TEMS, MapInfo (C); MCOM (I)

    Cell Planning Tool       TEMS Cellplanner (C); MCOM (I)
Radio Network Growth Flow
          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
   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
      Initial Tuning

• Produce Coverage Plot
• Identify Coverage Holes
• Identify Interference Area
• Optimize Neighbor Relations
• Find Hardware/Installation Problems
• Verify Parameter Setting
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          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?
    Measurement Will Depend on
            Objective
       ?          Preparations
                                      Possible Objectives

Clear objective   Check equipment     • Coverage analysis
Why should this
measurement be
                  Get input files
                  Prepare route
                                      • Trouble shooting
done
                  External antenna?   • Scanning
                                      • Verify network changes
Performing Measurements with TEMS
Drive Test
  • Large areas
  • Specific areas
Walk Test
Scanning
                    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
                  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
                             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         OUTPUT

Finding a new    TEMS INV in         Received SS on
frequency        scanning mode       different ARFCN
Area Network     Set ARFCN to scan   plot
Scanning                             New frequency
Analyzing Measurements
Post-Processing TEMS Logfiles
                        Geographical
 TEMS                   Presentation
Logfiles



           Statistics
            Report


                        Analysis
             Problem Cases
Low Signal Strength
• Interference
• Handover
• Call Setup Failure
• Dropped Call
• Misc.
             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
          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 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?
        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            Analysis


Identify areas with Rxqual > 5
Identify source using Map and STS
New drive test around problem area?
              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.
                     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-Processing


Specific area DT               Analysis


Look for:
Repeated handover (Ping Pong)
Repeated Intra-cell handover
Handover failure,
Unrealistic handover
Repeated Handover (Ping Pong)
         - Examples
Repeated Handover (Ping Pong)
     - Possible Reason 1




Merry-go-round Handover, Offset >
 Hysterisis
   Repeated Handover (Ping Pong)
        - Possible Reason 2
• Offset only in one direction e.g A-B for Inter
  BSC relation
        BSC 1                   BSC 2




        CELL A             CELL B




A -> B OFFSET = -5dB    No B -> A OFFSET
   Repeated Handover (Ping Pong)
     – Other Possible Reasons
                              No dominant Server


• No dominant server
• Locating penalty settings
  e.g. PSSBQ, PTIMBQ
• Too small hysterisis
  setting
  Repeated Handover (Ping Pong)
       – Possible Solutions
Antenna direction

Antenna Tilts

Plan for new site

Change Locating Parameter e.g.
KHYST or LHYST
Repeated Handover (Ping Pong)
     – Possible Solution
Change Parameter, KHYST or LHYST



                                   Hysterisis
      CELL A                                CELL B


                                      Handover
                                     From A to B
         Handover Case
      – Handover Reversion




Check layer 3 message
Handover command BSC correct?
Check reason for handover SS, RXQUAL
Target cell?
             Handover Reversion
             – Common Reason
Duplicates of BSIC BCCH combinations in neighboring list


                                     Handover command?

                                   610_12
 606_33
               610_31                                         610_31
                                 Serving cell
                                                            Neighbor cell 2
               Neighbor cell 1
                                            608_32
    608_32
                                                     Road
               Handover Reversion
                – Other Reasons
Uplink interference in target cell
Downlink interference at MS

Solutions
Interference Investigation
• MRR
• Statistics
• Scanning
                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?
   Handover Case
– Unrealistic Handover
          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
Call Setup Failure
        Call Setup Failure
 – Input Activities, Initial Tuning
   Activities
                    Measurement Type
  Initial Tuning    •Large Area Drive Test
(Acceptance Test)   •Short Call Sequences



Troubleshooting     Post-Processing Output
   (Customer        •Statistics Report
 complaint etc.)    •Geographical Report
                    showing failure positions
        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.
        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
                            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
                          SDCCH\8
          BCCH

                  TCH




                                     TCH


                                           TCH


                                                 TCH


                                                       TCH


                                                             TCH




CHG0
                                                                        SEKTOR B
           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
 GPRS Verification &
      Optimization
with TEMS Investigation
   GPRS Measurement Activities
• GPRS Performance Prediction
• GPRS Field Measurement
   GPRS Performance Prediction
          - Overview
• GPRS RNAP Service uses TEMS Inv to predict
  following performance:
  – Throughput
  – Cell Reselection & Routing Area Update
    GPRS Throughput Prediction
• Perform Throughput prediction for each
  coding scheme
      Cell Reselection Prediction
• Dedicated mode drive
  test
      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
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
       GPRS Field Measurement
        - Type of Measurements
• Application Performance Test
  –   Ping
  –   WWW
  –   FTP
  –   WAP
• Mobility Performance Investigation
  – Cell Reselection
  – RA Update
      GPRS Field Measurement
   - Application Performance Test

• Attached performance
  – Attached Time = Attach Complete msg – Attach
    Request msg
  – Attach Success Rate
• PDP context activation performance
  – PDP context activation = Activate PDP Context
    Accept msg – Activate PDP context request
• Throughput on RLC level
• Delay
    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
      GPRS Field Measurement
       - Mobility Performance
           Investigation
• Number of Cell Reselection & RA Update
• TCP Outage Time
• Cell Reselection Failure
Mobility test CRH = 4, CRO = 4
                     .
     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!

				
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posted:4/13/2012
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