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3G Network Drive Testing detailed Learning
- 1. WCDMA Introduction and Overview ? WCDMA concept and Architecture ? Spreading and Scrambling ? Codes and Channels ? Code tree ? Rake Receiver ? Soft, Softer and Hard hand over ? Power control - fast and slow WCDMA – Drive test Overview using TEMS Investigation ? TEMS Parameter for WCDMA ? Optimization Tips for WCDMA ? WCDMA Tools for Drive Test ? 3G Voice Call Testing ? 3G Packet call & Video call testing ? 3G Drive test KPI overview ? 3G Optimization overview WCDMA Introduction and Overview ? WCDMA concept and Architecture ? Spreading and Scrambling ? Codes and Channels ? Code tree ? Rake Receiver ? Soft, Softer and Hard hand over ? Power control - fast and slow WCDMA – Drive test Overview using TEMS Investigation ? TEMS Parameter for WCDMA ? Optimization Tips for WCDMA ? WCDMA Tools for Drive Test ? 3G Voice Call Testing ? 3G Packet call & Video call testing ? 3G Drive test KPI overview ? 3G Optimization overview Interview and drive test tips
- 2. WCDMA Frequency and Spectrum ? Uplink=1920MHz -1980 MHz ? Downlink= 2110MHz -2170MHz ? Bandwidth=60 MHz Actual B.W assign to operator is 5MHz And out of that 3.84 MHZ is utilize. In WCDMA frequency reuse factor =1 because time and frequency remains constant.
- 3. ? In WCDMA first following process is done before Reading BCCH frequency. Slot Synchronization Frame Synchronization Scrambling Code CPICH is pilot which will read BCCH information After Synchronization . In WCDMA following Channels use for various function in UL/DL. Downlink:- Uplink:- 1.DL DPCH 1.UL DPDCH 2.DL CCPH 2. UL DPCCH 3. P-CCPH 3. UL CPCH 4. S-CCPH 4. UL PRACH 5. SCH 5. HS-DPCCH 6. PICH 7. CPICH (primary and secondary) 8. AICH
- 5. ? Spreading:- This is used to increase the B.W of the signal beyond the bandwidth normally required to accommodate information. For Spreading OVSF code are used which is known as Orthogonal variable spreading factor code . Spreading factor=chip rate/symbol rate . Scrambling – Scrambling is used on top of the spreading so , it does not change the signal bandwidth but only makes the signal from different source separable from each other. Process gain = 10 log (chip rate/bit rate) As bit rate increase process gain decrease . Cell breathing is situation where cell foot print decrease due to large amount of user access the network beyond the capacity of that particular cell.
- 6. ? Eb /NO= Bit energy/Noise energy ? Ec/No = Chip Energy /Noise Energy. ? Ec/No= Eb/No - process gain ? As per Eb/No is fixed for each service for Ex: voice =2 and video=4 ? Ec/N0= 2- 10= -8 for voice(for voice -8 is good limit) ? Ec/N0= 4-18= -14 for video(for video -14 is good limit) ? Process gain(voice) = chip rate/bit rate= 10dB ? Process gain (video) = chip rate /bit rate= 18dB ? Chip rate = 3.84Mchips in WCDMA.
- 7. WCDMA codes
- 8. Code tree
- 10. Soft Handoff
- 12. For Speech drive Test
- 13. Mobile TX power Received signal strength indication Target Signal to interfere ratio Signal to interfere ratio Speech quality mean opinion square Dedicate channel GSM/WCDMA
- 14. Speech quality SQI MOS Algorithm Downlink Dedicate channel BLER%
- 15. Active Set- Currently serving Cell Measured neighbor- Defined Neighbor Detected Neighbor- Undefined strong detected server UARFCN DL- UMTS Absolute radio frequency channel number
- 16. Ranges for Radio Parameter ? 1. CPICH EC/No- 0 to -34 dB. ? 2. CPICH RSCP - -15 dBm to -140 dBm for each rake finger. ? 3.Ms TX power – -44 dBm to 60 dBm ? 4. UTRA Carrier RSSI - -20 dBm to -140 dBm for each rake finger. ? 5. SQI MOS - 1 to 5 ? 6. SQI - -20dBQ to 30 dBQ ? 7 . SIR - -30 t0 20 db (signal interfere ratio measured on DPCCH ) ? 12.2 Kbit/s: 30 dBQ 10.2 Kbit/s: 28 dBQ 7.95 kbit/s: 28 dBQ 7.40 kbit/s: 27 dBQ 6.70 kbit/s: 27 dBQ 5.90 kbit/s: 24 dBQ 5.15 kbit/s: 21 dBQ 4.75 kbit/s: 19 dBQ
- 17. Drive Test KPI ? Parameter- ? RSSI – In Between -75 to -85 dbm ? RSCP – In Between -75 to -85 dbm ? Ec /Io – In Between -8 to -10 db ? FER – 1% or 2% ? Ms TX Power - Between -5 to -10 ? Soft Handoff – 35% of total time
- 18. Use full Plots ? Server Plot – Useful to find out Swap or Overshooting. ? UE Plot - To Check Neighbour Relation. ? RSCP Plot- Coverage holes ? Ec /No- for good Throughput and removing pilot pollution. ? 4th best Server – Ec/no should be > -10db ? 5th best Server – Ec/no should be > -10db
- 19. Condition for Radio Environment ? Pilot Pollution – RSCP >= -85dBm & Ec /Io =< -10 dB Coverage Limited – RSCP <= -85dBm & Ec /Io => -10 dB Poor Radio Condition- RSCP <= -85dBm & Ec /Io =< -10 dB Good Coverage – RSCP >= -85dBm & Ec /Io => -10 dB
- 20. 3G –voice call testing SCFT-Single Cell Functional Test ? Before the single site verification, we should only ensure the following conditions have been met. – Alarm Check – Cell Status Check – Parameter Check ? Alarm Check / Cell Status Check – The product support engineer will be responsible for checking and resolving all the alarms. It is important for the optimization engineer prior to any field test to check with product support engineer regarding any alarms especially intermittent alarms. ? Parameter Check – The optimization engineer need to ensure the radio part parameters configuration list has been achieved. In the list the radio part parameters includes: the scrambling code, power setting, neighbor cell list, handover parameter etc.
- 21. 3G –voice call testing ? Site Verification Items: – Installations: CPICH RSCP, CPICH Ec/Io, Rx Antenna Swap Test – Settings: Frequency & SC, Cell reselection parameters, LAC/RAC, Neighbor List. – Functions: LA/RA update, 3G<->2G Cell reselection, SMS (MT & MO), Voice (MT & MO), VP (MT & MO), PS Attach & Detach, PS service, Voice/VP/PS soft handover, Voice 3G- >2G handover
- 22. Testing On CELL site – Items: Voice Call (MT & MO) – Purpose: Verify the voice call function is normal and the voice call quality is good – Method: Make the dialing test of 3G voice service between two 3G mobiles, one for the terminating call and another one for the originating call. Test the voice communication quality – Items: Voice Call (MT & MO) – Purpose: Verify the voice call function is normal and the voice call quality is good – Method: Make the dialing test of 3G voice service between two 3G mobiles, one for the terminating call and another one for the originating call. Test the voice communication quality
- 23. Feeder Connection Check Test Process Items: Antenna swapping test Purpose: Verify the Rx feeder installation is right. Method: Switch the transmitter from one feeder to another, check the RSCP changed or not. If no change happened, it means that the feeder is correct. Notes: Check the RSCP from scanner
- 24. Problem and Solution ? In the site verification, following problems have been found – Scrambling Code Setting is wrong: The scrambling code from scanner and mobile is different from the planning – After feeder swapped, the CPICH RSCP is 20dB lower than before. ? Scrambling Code Setting is wrong – The Scrambling Code may be wrong in RNC, check the datasheet in RNC. – If the Scrambling Code from scanner is the same as that of another sector in same site planned, maybe the TX/RX feeder is crossed to the another sector. ? After feeder swapped, the CPICH RSCP is 20dB lower than before: – The RX feeder is crossed to the antenna of another sector. In this case, the CPICH RSCP will be high in the coverage area of the other antenna. Check the connection between the feeder and the antenna.
- 26. Drive Test tool for drive ? Sony Ericsson C702 (capable of Scanning) ? Sony Ericsson Z750i (capable of Scanning) ? PCTel SeeGull LX WCDMA 2100 ? PCTel SeeGull LX Plus WCDMA 2100 ? Global Sat BU-353 (NMEA-0183) ? Garmin 10 Mobile Bluetooth (NMEA-0183)
- 27. 罢丑补苍办蝉……