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To check out RF parameters of a particular site we perform Drive Test. It is the most common and may be the best way to analyze performance of a particular site or cluster. We can evaluate coverage, system availability, network capacity, and call quality and many other RF parameters by performing Drive Test. In practical environment we abbreviate Drive Test as “DT”. So Although DT gives idea only on downlink side of process, it provides huge perspective to the service provider about what’s happening with a subscriber point of view.
Drive testing is basically collecting measurement data with a TEMS phone, those measurements are then further used to analyze the problem and to provide use full recommendations to solve them. Please note that a successful analysis should be supported by handling network statistics tools and careful evaluation of coverage predictions from a cell planning tool (Planet, DB-Planner, TEMs Cell Planner, etc…).
TEMS Investigation is a basic tool used for Drive Test.
In all Drive Tests we perform some common operations to check out many key parameters. Those basic operations include taking Short calls. (Short Duration calls), Long calls (Long Duration calls), checking Handovers, GPRS testing.
These are basic and common operations done by an RF Engineer in all types of Drive Test along each sector of a site. Though they pin out different RF parameters within these basic operation, for example system availability, network capacity, signal quality level, Interference, signal to noise ratio, efficient assignment of traffic and control channels etc. These basic operations and RF parameters allows an RF engineer to give conclusion about possible problems and different issues related to network performance for example no or Delayed handovers, blocked calls, overshooting etc. So further we will discuss in detail about the basic operations, RF parameters, common issues and their solutions.
There is some information that should be collected before Drive Test. So we usually need a solid preparation before performing Drive Test. Then DT itself is not a short process, it includes many sub operations. So let us discuss the whole process of DT in form of steps below.
A DT includes the following process:
1. Basic Information and Route Definition
2. Hardware equipment preparation.
3. Drive Test.
Route Definition:
First of all we define a route. This contains information regarding to the road and the distance to be covered along each sector. We use MapInfo Professional (application software) for selecting a route along each sector. Normally highways and major roads are preferred. Distance along each sector to check its performance depends upon height and type of antenna.
As we already said the two factors on which route definition depends are the height and type of an antenna. So let us talk about type of antenna first, As in Telenor Project we use both 900 and 1800 GSM band, so there are different coverage patterns. As 900 band is used for coverage and 1800 is used for capacity, so obviously for a coverage site we calculate RF parameters along each sector for longer distance, and for a capacity site we calculate RF parameters along each sector for shorter distance.
The other factor is height, so TP (Telenor Pakistan) suggests for a site, using antennas at 30 meters height we use to perform Drive Test up to 4 Kilometers along Each Sector. For a site, using antennas at 45 meters height we use to perform Drive Test up to 6 Kilometers along Each Sector. And for a site, using antennas at 60 meters height we use to perform Drive Test up to 8 to 10 Kilometers along Each Sector. Another factor which counts in deciding distance is type of antenna. But if we are using a dual band antenna (supporting both 900 and 1800) then we will follow the rules defined be TP (Telenor Pakistan).
Hardware equipment preparation:
This Preparation means to make sure that the required equipment to perform Drive Test is ready. DT required equipment includes:
1. DC to AC Inverter
2. laptop with TEMS software
3. laptop power adaptor
4. TEMS soft or hard dongle
5. TEMS USB Hub or a norma-l USB hub
6. GPS
7. Car cigarette lighter extension cable for phone chargers and GPS
8. TEST mobiles.
9. USB data cables to mobiles
10. Test mobile battery chargers or a full charged backup battery per mobile
A DT engineer should make sure that the TEMS mobiles are connected on their TEMS hub holders and placed on the car’s dashboard. We generally uses external antennas for better signal quality. Another thing which should be managed before DT is to carry a contact list of the responsible RF engineers and the OMC engineers on shift so that he may contact them in case of any issue or help.
Drive Test:
This is the part in which actual performance test of a site is taken. Actual procedure of Drive Test includes:
1. Short calls on sector 1 at 900
2. Short calls on sector 2 at 900
3. Short calls on sector 3 at 900
4. Short calls on sector 1 at 1800
5. Short calls on sector 2 at 1800
6. Short calls on sector 3 at 1800
7. Short calls on sector 1 at BCCH
8. Short calls on sector 2 at BCCH
9. Short calls on sector 3 at BCCH
10. Long calls on sector 1 at 900
11. Long calls on sector 2 at 900
12. Long calls on sector 3 at 900
13. Long calls on sector 1 at 1800
14. Long calls on sector 2 at 1800
15. Long calls on sector 3 at 1800
16. Long calls on sector 1 at BCCH
17. Long calls on sector 2 at BCCH
18. Long calls on sector 3 at BCCH
19. Handovers test.
These are the basic operations that should be done by a DT engineer. All these basic operations and Events are recorded in form of a Log File. And that Log File is then further attached in DT report and used to analyze issues.
Procedure:
TP (Telenor Pakistan) suggests a specific pattern to perform the above basic operations.
• All test calls should be terminated to a PABX (fixed line) test number provided for that purpose.
• The drive testing scripts should be configured to provide the following test sequences:
1. MS1: configured to run on dedicated mode one continuous test call (one long call to be established and carried through until the end of the DT). If the call is dropped the DT engineer should re-establish a new call immediately.
MS2: configured to run on idle mode throughout the drive test locked on the 3 BCCHs of the site.
A DT engineer when start DT of a site he must start with Handovers check by just staying near the site using self Handover option of TEMS. Then Lock both MS1 and MS2 on 900 band and set one to long call and other to short calls and start Drive on defined route for sector 1 away from the site. And when route completed, Lock both MS1 and MS2 on 1800 band and set one to long call and other to short calls and start Drive on defined route for sector 1 toward the site. Same process would be done along Sector 2 and Sector 3.
Each drive test must be clearly documented. Additionally, the time of the drive test activity must be synchronized with the OMC, so that each drive test data set collected can be correlated with the OMC statistics in order to produce KPI snapshots. Prior to this test, PCU, SGSN and other GPRS connectivity network elements have to be verified that are working.
Possible Expected results
• The drive test has been completed as planned
• Any issues have been documented and reported
All drive tests must be able to be aligned with the OMC statistical reports therefore each drive test should be clearly documented (duration, major events, issues etc).
Before starting the drive tests the drive test engineer should contact the OMC shift engineer to make sure the site is alarm free.
Once the drive test team is on the site and before starting the measurements they should coordinate with the OMC shift engineer and the DT coordinator to deactivate the Cell Barring and enable the IHO.
Log files should be named according to a specific naming convention [Annex 07].
During the drive tests the engineer should ensure that there are no swapped (crossed) sectors problems, all neighbors declared are present and all RF frequencies given are correct.
During the drive tests the DT engineer should note all major events (drop calls, blocked calls, handover failures) and shall identify their main causes.
Upon completion of the DT activity the DT engineer should verify that all log files are not corrupted. In case of any log file problems the DT team should repeat the test immediately. Finally he should report to the DT coordinator the successful completion of the drive test.
The DT coordinator should then ensure that the site is locked again after the specified end time of the DT activity.
The DT coordinator should handover the log files and the list with the description of the major events and their causes (drop calls, blocked calls, handover failures) to Telenor Pakistan Head office.
ITS my personal data.
Posted by saqlain231
yes we can by
1.processing and analysis
2.Improve management
3.hardware of that network
Posted by crouse
We improve our Drive test analysis by using well equipments through which we connect our cell sit well also we make sure that the drive must be on the correct way and we don't move far away from our mark up cell.
Posted by HamidAliKhan
By doing following things:
1.)Good Route Defining
2.)Data processing and analysis (voice and data)
3.)Power Control Management
Posted by sagitraz
Only by knowing the network and hardware of that network well !!
Posted by waqqas1
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