3G Tems Parameters Investigation and Drive Testing

Syed Mohib Hussain (ZTE Engineer Team C-III)

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WCDMA

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What is Drive Test?

•The Drive Test is a test performed in cellular networks regardless of technology (GSM, CDMA, UMTS, LTE, etc. ...) usually Performed in order to Analyze and optimize the Network Quality.•Drive Test is used to analyze and optimize the network quality.•Although by the analysis of KPI's we can identify problems of Parametrical Issues e.g. (CDR, Interference, Traffic etc. etc….) while the drive tests allow a deeper analysis in the field. Identifying areas of each sector of coverage, interference, evaluation of network changes and various other parameters.

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内部公开▲Why we Perform Drive Test?

• Every alive network needs to be under continues control to maintain/improve the performance.

• Optimization is the only way to keep track of the network by looking deep into statistics and collecting and analyzing drive Test data.

• Drive Test helps operation and maintenance for trouble shooting purpose.

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内部公开▲WCDMA 3G UMTS

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内部公开▲Drive Test Tools

Tools used for 3g Drive Testing are enlisted below:

Tems Investigation, Nemo , Probe for WCDMA (Software) Doungle (License) User Equipment's (Sonny Ericsson W995) Data card (3G supported for data testing) GPS Scanner Invertor

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内部公开▲Received Signal Strength Dedicated Ground Floor

Drive Test Types:

The main types of Drive Test are :

•Performance Analysis•Integration of New Sites and change parameters of Existing Sites•Marketing•Benchmarking

Performance Analysis:Tests for Analysis Performance is the most common, and usually made into clusters (grouping of cells), ie, an area with some sites of interest. They can also be performed in specific situations, as to answer a customer complaint.

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内部公开▲New Site Verification:

When the site is completely integrated , Drive tester team will start to perform site investigation.The detailed sub-activities are outlined below:

1.Rigging Audit2.Site Verification3.Functionality Test’s4.Acceptance Test

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内部公开▲Site Verification:

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内部公开▲Test Performed:

Test Performed on a New Roll out site are enlisted below:

•Sector Swap•Audio calls•Video calls•R99•HSPA (HSDPA & HSUPA)•Cell Reselection•IRAT (Inter Radio Access technology)•Soft and Softer Handovers•Coverage Test

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内部公开▲ Site Verification:

Voice / Video CallsVerify on per Basis for all carriers:

•RSCP•Ec/No•Scrambling code•LAC/RAC•Cell ID•Etc etc.

Data and Throughput Test:HSDPA / HSPUPA / R99Verify on per Basis for all carriers:

•RSCP•Ec/No•Scrambling code•LAC/RAC•Cell ID•Max & Avg Throughput•Etc etc

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内部公开▲Static Test:Audio Call: Performed number of calls as defined by the operator on all the three sectors of sites in order to determine if any call failure , dropped or blocked is found.

Video Call: Just Like Audio Calls number of video calls are also performed on all the three sectors of sites in order to determine if any call failure , dropped or blocked is found. Video call found should be successful.It Takes 64kb/s data to transmit a call.

R99: (Release 99) First Step Advancing toward Global 3G network. Can Support data rate up-to 384kb/s and a dedicated channel is allocated for each specific user. Perform Number of R99 Test by making a dial up connection and verify the achieving speed.

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内部公开▲Static Test:

HSPA (HSDPA & HSUPA):HSDPA:High Speed downlink packet access is the total speed on a downlink channel Ideally on single carier HSDPA will Provide Data Rate upto 14Mb/s and for Dual carrier as like on Zong It is Providing data Rate upto 42 Mb/s.Large and Huge Data Contained Files are downloaded Via Http or FTP to perform this test. On Zong Minimum Average Speed for HSDPA Should be more than 9mb/s. Moreover HSDPA used Dedicated Shared channel.One Channel shared with number of users.

HSUPA:High Speed Uplink packet access is the total speed on a uplink channel Ideally on single carrier HSUPA will Provide Data Rate upto 5Mb/s and for Dual carrier as like on Zong It is Providing double than that/Large and Huge Data Contained Files are uploaded Via Http or FTP to perform this test.HSUPA always used E-DCH Channel.

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内部公开▲Cell Reselection:• This test is performed to check weather

our cell is camping to better serving cell or not in Ideal mode while moving from one node B to another or one Sector to another.

• Specific Threshhold level will be adjusted for this parameter. It Commonly depends upon the RSCP and EcNo.Mostly If EcNo Exceeds <-14 it will Reselect a new cell.

• Forcefully Test: WCDMA to forcefully on GSM

from Inter Radio access technology option and then Back to WCDMA Ue should not exceeds from 2secs while reselecting a WCDMA cell from No Service mode to RRC Eastablished.

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Inter Radio Access Technology (IRAT):

Inter Radio Access Technology Test Tells us in case we are in dedicated mode and some where coverage levels of WCDMA are degraded or we are coming out from the coverage area of WCDMA then our call instead of Dropping simply switched on to a GSM Network.

Same like in this test we will check weather our cell is properly mapped with 2G desired cell and MSC or not and is properly switching to GSM or not.

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内部公开▲Handovers:Types of Hand over:

1.Soft Hand over: Make Before break. Between two Node B’s at a time connecting with number of cells and first of all making the connection with better serving cell then release.2.Softer Handover: Make Before break. Between different sectors of the same Node B and first of all made the connection with better serving cell then release.3.Hard Handover: Break before make. Intra frequency handover in WCDMA.

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内部公开▲Sector Swap:

• Sector Swap is one of the major Test in GSM,CDMA,UMTS,LTE… Drive Testing.

• In WCDMA 3g Sites we commonly faced a complete swap in a new roll out site.

• Sector Swap in Telecom means If you are standing in the coverage Area of Sector 1st but you are going to be served with 2nd sector and same like if you are standing in-front of sector 2nd and serving cell you measures will be showing the results of sector 1st and same as In front of 3rd Sector you will be served by sector 2nd.

• Here it shows abnormal behavior of the network.

• By sector swap quality should be degraded and as a results Drop calls and level of interference should increase up to its extent.

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内部公开▲Coverage Test:

• Coverage Test is used to analyze the network by monitoring RSCP, EcNo, CQI, SIR, BLER etc etc.

• Coverage holes and others Missing or Detective Neighbors Information can be also measured.

• Block calls , Drop calls, Interference , PS Attach Successful and Failure and other abnormal event can also be monitored.

• Different Colour Coding shows the Ranges of different Parameters.

• Map Info Tool is commonly used to Plot the ranges of Power and Interference by using Thermatic.

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Radio Parameters:

• CPICH EcNo• CPICH RSCP• Tx Power• UTRA Carrier RSSI• SIR• Target SIR• SQI• RRC State• Mode

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内部公开▲Radio Parameters:

CPICH Ec/No: Chip Energy by Noise. Common Pilot channel EcNo is the ratio of the energy of the chip and the combined power of all the signals including the specific pilot channel. It also shows the level of Noise disrupting the specific CPICH.

Ranges for EcNo: 0 to -7 Good -7 to -10 Acceptable -10 to -36 Bad

CPICH RSCP: Received signal Code Power is the level of the signal received by the U.E. or in simple RSCP is the total power of the entire cell or a specific Common Pilot Channel received by the user Equipment.

Ranges of RSCP: -30 to -75 Good -75 to -85 Acceptable -85 to -140 Bad

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内部公开▲Radio Parameters:

Tx Power: Tx Power is the transmitting power of the mobile station. Its value can vary from 50 to -50.The minimum the Tx Power of the mobile station the better it is for call quality.Tx Power is the power of mobile station only measured in the dedicated mode and commonly mobile will support the call in case when you are in a low coverage area it will increase its own power to support your call avoiding Droped.RSSI: Received Signal Strength Indicator is the total power of the entire common pilot channel received by the Mobile station Including Neighbours interference and noise as well of Neighbours and it self also.RSSI= RSCP + EcNo

RSSI Ranges:0 to -75 Good-75 to -85 Acceptable-85 to -140 Bad

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内部公开▲Radio Parameters:

SIR: Signal to Interferance ratio is the ratio of energy in the DPCC ( Dedicated Physical control channel) to that of the interferance and noise received by the User Equipment.

Target SIR: It is the target signal to interferance ratio that Mobile Equipment is supposed to achieve by increasing or decreasing its power. It is usually Set by the use of Power Control Procedure.

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内部公开▲Radio Parameters:

SQI: It is the speech quality index which is a parameter to rate the voice quality on that particular call. It ranges from 0 to 30. while 30 being the Best Value.Adaptive Multi Rate (AMR) is also used to enhanced the speech or the voice quality of the specific call.WCDMA use AMR Sourc Coding.AMR vary with different Ranges Highest AMR Value is 12.20 and lowest AMR value is 4.75.

RRC State: It tells the current state and channel as in idle or dedicated.

Mode:It is the Mode that We are Using Weather GSM or WCDMA.

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Serving and Active Set + Neighbour:

Cell I.D: This is the Identity or name given to a particular Node B and its cells by the operator.

UARFCN: Universal Absolute radio Frequency channel Number is the frequency band allotted to the operator. One Spectrum band width is of 5MHz in WCDMA or 3G.Frequency for Uplink allotted to all the operators vary between 1920 to 1980 MHZ.WhileFrequency for Downlink allotted to all the operators vary between 2110 to 2170 MHZ.

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内部公开▲Serving and Active Set + Neighbour:

Cell Name: Specific Name of the Node B alloted by the Operator according to its location and Serial value.

Scrambling Codes: Scrambling Codes are usually used to identified different cells of a node B.They are of Two types.1- Secondary Scrambling Code2- Primary Scrambling Code

Secondary Scrambling Code: Used in a Beam forming case.

Primary Scrambling codes: (0 to 511) Are actually the Scrambling codes usually used to identified different sectors. They totally lies from 0 to 8191. More over 512 PSC are divided into a group of 64.Each contains 8PSC.Total Down link Scrambling Codes 16*8=512.

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内部公开▲Serving + Neighbours

AS: Set of Scrambling codes on which the user equipment is currently latched on and there can be at least maximum three scrambling's codes in a Active Set.

MN: Neighbor cell that is detected by user equipment as a neighbor. Soft and Softer Handover decision should be taken by measuring the Stronger RSCP and EcNo then that of Active Set at least 32 Neighbor cells can be added in a single 3g site.

DN: It is also the neighbor cell which is detected by the U.E but is not defined in our network. Hence the U.E does not handover onto these cells. It can be because of Overshooting, incomplete neighbor list or in case of a new site, It is very important to optimize a network and have no DN’s as they are one of the major reasons of call drops in 3G.

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HSPA and GSM Line Chart:

• This window gives us the data speed for both 2G and 3G depending on the mode of user equipment.

• RLC DL Throughput ---- This is the total throughput on the downlink at that particular point.

• You will find throughput values in Kb/s.• RLC DL Throughput average should be more than 9mb/s.

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内部公开▲Pilot Pollution

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内部公开▲Pilot Pollution:

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