TEMS DRIVE TEST

SAQIB BABAR

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TEMS: Testing Equipment for Mobile System

OBJECTIVE

The objective of the drive test is to check the physical situation of our network.

The important parameters check during drive test are: Rx-level, Rx-Qual, C/I (carrier to interference), BCCH,TCH.

Drive test inform us about the weakness in a coverage.

Any further step to improve the network, is based on the drive test data.

Modes of Drive Test:

Drive test performs in two modes:

Dedicated modeScanned mode

Dedicated Mode

During this mode we analyze our network by making a call.

The different aspects check during this analysis are:

Rx-Level

Rx-Qual

C/I

Over shoots

Call Drop & Handover.

Scanned Mode In this mode of drive test we only perform the scanning of

the frequency.

By scanning we mean, to check the Rx level of the down-

link frequency channels i.e. we analyze only BCCH.

Though this type of drive test could not gives us the real picture

of our network, but we got the idea of our coverage.

How to perform Drive Test?

Drive test is perform with TEMS software i.e TEMS Investigation GSM4.1

Along with this software we have a TEMS mobile.

Connecting Procedure:STEPS:1. Open TEMS.

2. Go to CONFIGURATION & load cell file.

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3. Now, USB of GPS is inserted in its port.

4. Go to port properties & check the selected port. Then to ADD EQUIPMENT select the port (i.e the one that is last check)

5. Next, Follow the same procedure for mobile i.e TEMS.

6. The GPS is Known as NMEA0183 & TEMS as R512m

The configuration becomes: Cell FileConnect AllTEMS GPS

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7. Now press connect all, which connects both TEMS &GPS.

8. Then go to MAPS and add the map +roads from Layer Control.

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For DEDICATED MODE :

. Go to control & dial the call.

. Then go to LOG FILE in Menu Bar select the Recording properties, & start Recording.

. Go to GSM & start analyzing, Rx-Lvl, Rx- Qual, C/I.

GSM analysis in Dedicated mode.

For Scanned mode:

After adding equipment & map, select Frequency scanning instead of normal mode in main menu bar.

Select mobile station (MS1 or MS2).

Go to scanning & select properties, there we select manual

selection & check the ARFCNs which we want to scan.

Also Decode BSIC (Base station identity code),& start scanning.

Go to Log file & then start recording.

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Scanned Mode Analysis:

Important:

Since all of analysis are based upon drive test data so a lot of care needed during drive test.

An ideal drive test is the one in which every street after 100m in a populated area is covered to collect log file data.

It is not necessary to go near the site but the coverage area of that site should not left

The maximum sped of the car is 60km/hr.

During drive test it is necessary to analyze the data our self.

Points to Remember:Full Level: It includes those time slots in which data is being

transferred from both the sides, means from tems & the dialed number.

Sub Level: It includes Those time slots in which data is only

being transferred from the tems.

In drive test we record both full- level & sub-level data,

But we analyze only sub-level data.

The unit of Rx-Qual is BER (Bit Error Rate).

Its range is from 07. Greater the value worst be the quality.

The greater the carrier to interface (C/I) , the higher be the efficiency.

Carrier to interference:

C/I > 9db .. For hopping

(for co-channel) >12db. For non-hopping

C/A (+,-) > -9db.

(For adjacent channel) SQI (speech Quality Index): It takes the analysis from BER & FER (frame error rate) & accordingly shows us the speech quality that human ear receive. C1 & C2: This behavior displayed in idle mode & shows us the strongest cell in which we connect & the next strongest cell. If we have two frequencies then it shows the dominant server.

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