55010408 3g Drive Test Learning

7/31/2019 55010408 3g Drive Test Learning

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WCDMA Introduction andOverview

• WCDMA concept andArchitecture

• Spreading and Scrambling• Codes and Channels• Code tree• Rake Receiver• Soft, Softer and Hard hand over• Power control - fast and slow

WCDMA – Drive test Overviewusing 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 andOverview

• WCDMA concept andArchitecture

• Spreading and Scrambling• Codes and Channels• Code tree• Rake Receiver• Soft, Softer and Hard hand over• Power control - fast and slow

WCDMA – Drive test Overviewusing 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



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.



• In WCDMA first following process is done before ReadingBCCH frequency.

Slot Synchronization

Frame SynchronizationScrambling Code

CPICH is pilot which will read BCCH information AfterSynchronization .

In WCDMA following Channels use for various function inUL/DL.

Downlink:- Uplink:-

1.DL DPCH 1.UL DPDCH

2.DL CCPH 2. UL DPCCH

3. P-CCPH 3. UL CPCH4. S-CCPH 4. UL PRACH

5. SCH 5. HS-DPCCH

6. PICH

7. CPICH (primary and secondary)8. AICH



WCDMA Spreading process



• Spreading:- This is used to increase the B.W of thesignal beyond the bandwidth normally required toaccommodate information.

For Spreading OVSF code are used which is knownas 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 signalbandwidth but only makes the signal fromdifferent 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 printdecrease due to large amount of user access thenetwork beyond the capacity of that particular cell.



• 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 goodlimit)

• Ec/N0= 4-18= -14 for video(for video -14 is goodlimit)

• Process gain(voice) = chip rate/bit rate= 10dB

• Process gain (video) = chip rate /bit rate= 18dB

•

Chip rate = 3.84Mchips in WCDMA.



WCDMA codes



Code tree



Rake Receiver



Soft Handoff



Power Control types



For Speech drive Test



Mobile TX power

Received signalstrength indication

Target Signal tointerfere ratio

Signal to interfereratio

Speech quality meanopinion square

Dedicate channel

GSM/WCDMA



Speech quality

SQI MOS Algorithm

DownlinkDedicatechannel BLER%



Active Set- Currently serving CellMeasured neighbor- Defined Neighbor

Detected Neighbor- Undefined strong detected serverUARFCN DL- UMTS Absolute radio frequency channel number



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 rakefinger.

•

5. SQI MOS - 1 to 5• 6. SQI - -20dBQ to 30 dBQ

• 7 . SIR - -30 t0 20 db (signal interfere ratio measured onDPCCH )

• 12.2 Kbit/s: 30 dBQ

10.2 Kbit/s: 28 dBQ7.95 kbit/s: 28 dBQ7.40 kbit/s: 27 dBQ6.70 kbit/s: 27 dBQ5.90 kbit/s: 24 dBQ

5.15 kbit/s: 21 dBQ4.75 kbit/s: 19 dBQ



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



Use full Plots

• Server Plot – Useful to find out Swap

or Overshooting.• UE Plot - To Check Neighbour

Relation.

• RSCP Plot- Coverage wholes• Ec /No- for good Throughput and

removing pilot pollution.

• 4th best Server – Echno should be >-10db

•5th best Server – Echno should be >

-10db



Condition for Radio Environment

• Pilot Pollution –

RSCP >= -85dBm & Ec /Io =< -10dB

Coverage Limited –

RSCP <= -85dBm & Ec /Io => -10dB

Poor Radio Condition- RSCP <= -85dBm & Ec /Io =< -10

dB

Good Coverage –



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 checkingand 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.



3G –voice call testing

• Site Verification Items:

–

Installations: CPICH RSCP, CPICH Ec/Io, RxAntenna Swap Test

– Settings: Frequency & SC, Cell reselectionparameters, LAC/RAC, Neighbor List.

–

Functions: LA/RA update, 3G<->2G Cellreselection, SMS (MT & MO), Voice (MT & MO),VP (MT & MO), PS Attach & Detach, PS service,Voice/VP/PS soft handover, Voice 3G->2Ghandover



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



Feeder Connection Check

Test Process

Items: Antenna swapping testPurpose: 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



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 theconnection between the feeder and the antenna.

r ve



r vewindow

Data Drive Parameter with low through put



Data Drive Parameter with low through. put

Channelquality index

Modulationtechnique

As 64 QAM

is utilizedso lessHSDPA

throughputis less.

Case 2 with high throughput



Case-2 with high throughput

In this case 16QAM is used 100%and Throughput is

high



Data Drive

• There is 3 modulation technique QPSK,16QAM,64QAM.

• For high through put 16QAM and 64QAM should be utilized

high Utilization• So, if There is less Utilization of QPSK in downlink than data

throughput is also high’

• CQI is like SQI in speech which ensure good channel qualityfor data transfer.

•

Retransmission of HS- DSCH(High-Speed Downlink Shared Channel) packet is high thanalso throughput is decreases.

• In case of stationary Data Test- 2Mbits speed can beachieved

• In case of moving Vehicle – 800kbits to 1.2 Kbits speed canbe achieved.

• Application throughput is always 85% of physical layerdata rate throughput because at application level IPinclusion and overhead information will be there.

• Latency time is round trip time from server and for 3G it

should be 150 ms for 32 bit data .

http://en.wikipedia.org/wiki/High-Speed_Downlink_Shared_Channel

http://en.wikipedia.org/wiki/High-Speed_Downlink_Shared_Channel



• The modulation scheme and coding is changed on aper-user basis depending on signal quality and cellusage. The initial scheme is

Quadrature phase-shift keying (QPSK), but in goodradio conditions 16QAM and 64QAM can significantlyincrease data throughput rates. With 5 Code allocation,QPSK typically offers up to 1.8 Mbit/s peak data rates,while 16QAM offers up to 3.6. Additional codes (e.g. 10,

15) can also be used to improve these data rates orextend the network capacity throughput significantly.

• Data Throughput will be also depend on MS classwhich support 5,10 and 15 codes resp.

•

CQI- Channel quality information may include carrierlevel received signal strength indication (RSSI) and biterror rate (BER). I

• Channel quality indicators are messages that are senton a communication system (such as a mobile

communication system) that provide the remote

http://en.wikipedia.org/wiki/Phase-shift_keying


http://en.wikipedia.org/wiki/QAM







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)



Thanks……

55010408 3g Drive Test Learning

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