Drive Test is one way of measuring the quality of service (QoS) in mobile networks, in addition to the stationary measurement and statistics collection by the operator. As opposed to other methods, DT is a measure which takes place on the move. The objective of Drive Test is the most truthful recreation of the conditions in which the user uses the mobile network (moving with constant and different speed, change of the radio conditions) and behaviour of the user (the height of the antennas placing, calls setup and using web services according to the scenario based on the observation of user actions). As a result, the measures are close to the actual experience of the user who uses the mobile network.
Most measures include areas so-called ‘clusters’. The separate drive route is prepared for each cluster. When planning the route, different aspects are taken into account e.g. the type of the area which is measured (urban, rural … etc.), the service which is tested, the main movement of subscribers, the number of measuring hours available and many other factors that should be taken into account.
QoS (Quality of Service) specifies the guaranteed level of services quality ordered and received by the mobile network user during the service contract with the operator. As far as telecommunication services are concerned QoS are defined by three functions: access, information transfer and disconnection, and three criteria: speed, accuracy and reliability. The mobile network operator is obliged to provide services of a specific, guaranteed quality.
A special measuring car moves on the outlined drive route. This motor vehicle is specially prepared for measuring mobile networks, equipped with measuring devices, allowing the measurement of all network parameters necessary to evaluate the quality of services. A current position of the measuring car is acquired thanks to the GPS receiver built into the device. The car can not move faster than it was assumed during the drive route planning. Effects can be viewed on the home page RFBenchmark.
Only those measuring tools which comply with the ETSI standard are used for Dive Tests. In addition, each testing car is equipped with a radio scanner, which enables an independent measurement of the signal level in the three available technologies: 2G, 3G and LTE at the same time.
Thanks to these measurements and the report of their subsequent analysis, the operator of mobile network has information which allows to optimise the network, which means introducing changes to improve radio coverage or the quality and to introduce new services for their customers.
Cluster in telecommunications means a group of cells served by bandwidth which is accessible to the mobile network operator. The cell is a smaller area of the whole system. The area of the cell is dependent on the geographical conditions and the number of subscribers (microcells in urban areas, macrocells in rural areas). The number of cells in a cluster can take specific values counted according to the formula, e.g. 1, 3, 4, 7, 9, 12, 13, 16… etc. The conditions existing in the area decide about the number of cells in a cluster.
During Drive Tests measures the voice calls between the mobile terminal (the tested one) and the receiving device (e.g. ISDN, another mobile terminal) are made. Tested measuring voice connections may take place to and from the measuring terminal, depending on the set work order. When measuring, the voice quality is expressed as a single number in the range from 1 to 5 according to the MOS scale.
MOS (Mean Opinion Score) provides a numerical indication of the perceived quality from the users’ perspective of received media after transmission. The MOS is expressed as a single number in the range 1 to 5:
5 – excellent quality (full understanding of discussion, there is no need to concentrate during the call for full understanding and transparent communication),
4 – good quality (good level of understanding, little effort needed during the call to maintain full understanding of discussion),
3 – acceptable quality (noticeable decrease of quality – caller and receiver needs to focus during the call),
2 – poor quality (very bad quality – need maximum effort and full focus to understand what second person is talking about),
1 – unacceptable quality (despite of maximum effort it is impossible to understand what second person is talking about).
To guarantee objective and repetitive measurement results, one of the two subjective estimating speech methods (MOS) is used: PESQ or POLQA. What is more, different kind of information is collected, e.g. the number of successful and unsuccessful calls, the number of dropped calls, the call setup time, the type of speech coding which is used and many others. On the home page RFBenchmark the voice quality measurement results are available after selecting the icon
POLQA (Perceptual Objective Listening Quality Assessment) is an objective method of estimating the subjective evaluation of speech quality. The most often expected way is expressed as a single number in the range from 1 to 5 according to the MOS scale. POLQA is the follower of PESQ (Perceptual Evaluation of Speech Quality).
Measurements of the voice quality services and the internet services take place at the same time. An example of a measuring sequence is shown below.
|FTP DL (5x 5MB)||Downloading a 5 MB file in five parallel sessions from the test server|
|FTP UL (5x 5MB)||Uploading a 5 MB file in five parallel sessions to test server|
|HTTP Browsing: Kepler||Downloading the content of the test web page|
|HTTP Get (10x 5MB)||Downloading a 5 MB file in ten parallel sessions from the test web page|
|Ping (10x 32B)||Ten PING sessions where the size of the packet is 32B|
|Video: YouTube 30sec||Downloading video streaming from YouTube during 30s|
Throughput and RTT are measured parameters which are more important in terms of the user view. On the basis of these two-parameter analysis, we obtain information about the internet speed offered by the operator and about the purposes of the network connection usage. Different data are also collected, e.g: the amount of successful and unsuccessful FTP sessions, HTTP, Ping, the reason of the session failure, the technology type in which the mobile terminal worked and many others. You can check the speed of the internet on the RFBenchmark home page by selecting the icons.
Throughput in telecommunication determines the amount of data transferred correctly at a specific time and most frequently is given in megabits per second (Mbps).
RTT (Round Trip Delay Time) informs you about the length of time it takes for a message to be sent from our computer to the network one, plus the length of time it takes for an acknowledgment of that message to be received. The smaller the RTT value, the better. The similar parameter is (latency), which informs you about the length of time it takes for a message to be sent from our computer to the network one.
With the mobile application you can take measurements of the basic parameters of the cellular network. The application provides information including parameters such as the level and quality of the signal depending on the technology in which a mobile terminal operates (mobile phone), the cell ID to which the phone is currently attached, the mobile network operator, the country in which the terminal is located and its precise location on the map thanks to the built-in GPS receiver in the phone. In addition, on demand you can take measurements of the speed of the Internet during the download and upload of data and also the latency test. After clicking ‘Submit’ all measurements are sent to our server and are automatically displayed on the RFBenchmark map. The moment you notice a low voice quality connection, the lack of mobile internet services or any other service that should work, the application allows you to send a report with the current position, where the lack of the selected service has appeared.
The application works all over the world, and the results can be viewed on the home page RFBenchmark after selecting the icon.
The measurement of packet services in a mobile application for a given data transmission connection is done by a measuring sequence shown below:
1. Server Selection – based on the location, IP address and mobile network data several test servers are chosen with the smallest distance to the mobile phone, the servers are first pre-tested to determine the access time in order to choose the best one for later measurements of the internet connection.
2. Ping – test server response time to sent inquiry, initially a test request is sent, then the response time is checked by a series of 20 32B ping connections, the time interval between subsequent transmissions is 100ms, the maximum response time is 3 seconds and the maximum test time is 10s, the samples with too long response time are rejected,
3. Download – downloading data from the test server, downloading is done in up to four parallel sessions, each session begins with 100KB test file for a time of 1s, then the correct 10 MB file is being downloaded for a maximum of 10s,
4. Upload – uploading data to the test server, uploading is done in up to four parallel sessions, each session begins with 100KB test file for a time of 1s, then the correct 5MB file is being uploaded for a maximum of 10 seconds,
In Wi-Fi mode, the size of the file used to measure the download and upload speeds will be increased. This is due to the large bandwidth offered by wired Internet connections compared to the mobile Internet. The larger file allows accelerating the high-speed wired connection to the maximum speed.
For data transmission, the average data consumption per single speed measurement is 20 MB. For WiFi connection, the data consumption will be known after the implementation of changes.
Data is collected by the users of RFBenchmark mobile application with the use of “Test the quality of service” function. After the automatic measurement data is uploaded from the application to the server, the measurements are displayed on the map after selection of the data source: User reports.
Testing the quality of service in a mobile application is based on measuring three parameters: Ping and uploading and downloading speeds. All this information taken together can be used to determine the suitability of the connection for the implementation of individual Internet services. For example, browsing the Internet, using VoIP or watching HD videos.
Ping is a function which allows for measuring the delay of the packet transmission, i.e. packets of data in the network. The test involves the analysis of a connection between a phone and a test server. If the Ping value is too high, it can make services such as real-time games or VoIP conversations unavailable. The value is given in milliseconds (ms).
Ranking of mobile network operators refers to the entire area currently displayed on the map. Comparing the results for a particular location is also possible. Simply select the colored square which will display all the measurements taken for various operators at a given point. The information in the brackets contains the number of measurements taken for a given operator in the selected area.
Description of the scales for measuring Ping, uploading and ftp downloading speeds can be found by expanding the list “Explanation of service quality scales on interactive map”.
The scale describing the quality of the selected service is placed on the interactive RFBenchmark map. This scale describes the quality not only with colours but also with the numerical range. The measuring points are located on the map. The colour of these points corresponds to the appropriate result according to the quality of service scale. Explanations are given below.
1 – Very weak Signal Strength very bad quality of service – no service!
2 – Bad Signal Strength problems with access to basic services: voice and data seriously impacted
3 – Average Signal Strength possible voice drops – low download and upload speeds when connecting to Internet
4 – Good Signal Strengthu good quality of voice and data services
5 – Very good Signal Strength voice connections with very good quality – high upload and download speeds
1 – unacceptable quality (despite of maximum effort it is impossible to understand what second person is talking about)
2 – poor quality (very bad quality – need maximum effort and full focus to understand what second person is talking about)
3 – acceptable quality (noticeable decrease of quality – caller and receiver needs to focus during the call)
4 – good quality (good level of understanding, little effort needed during the call to maintain full understanding of discussion)
5 – excellent quality (full understanding of discussion, there is no need to concentrate during the call for full understanding and transparent communication).
up to 1Mbps – very slow, basic services available: web browsing, E-mail
from 1 to 3Mbps – slow, services: small files sending, audio streaming
from 3 to 8Mbps – normal, services: real time gaming, medium files sending
from 8 to 14Mbps – fast, services: SD video streaming, SD video conversation
from 14 to 100Mbps – very vast, services: FHD video streaming, FHD video conversations, large files upload
up to 1Mbps – very slow, basic services available: web browsing, E-mail, playing audio stream, watching videos up to 480p
from 1 to 5Mbps – slow, services: small files receiving, playing SD video stream
from 5 to 8Mbps – w normal, services: real time multiplayer games, VoD, watching videos up to 720p
from 8 to 15Mbps – fast, services:: watching videos above 720p, medium files receiving, SD video conversations
from 15 to 100Mbps – very fast, services: fast download of large volumes of data , 1080p & FHD videos streaming
from 100 to 300Mbps – ultra fast, all actually available mobile internet services are working
up to 30ms – very short, does not cause any problems in the use of Internet services
from 30 to 50ms – short, there may be minor problems in the use of online real-time gaming services
from 50 to 70ms – average, there may be significant problems in the use of real-time gaming services
from 70 to 120ms – long, prevents the use of real-time gaming services
from 120 to 9999ms – very long, above 150ms may cause problems with the use of HD conversations of VoIP calls. Above 200ms also causes problems with browsing the web, watching SD quality videos, watching HD quality videos, using multi-room service (3x HD video) and playing network games.