Wireless network is one of the most complex system and to make sure that the Network is working as per the standards and serving the users optimally, the telecom operators perform drive tests. These tests are carried out for different reasons, some times to optimize the network and some other times to debug certain issues in a particular area.
The repetitive drive tests are a big bottleneck to the network operator in terms of money spent for carrying out the operation and the time spent to debug certain issues. To minimize these 3GPP standardization groups proposed new techniques to minimize the amount of drive tests by collecting information from mobile users. The information can be on different kinds of measurements, handovers, or signalling failures.
There are two different type of MDT (Minimization of Drive Test)
MDT functionality involving measurement performance by UE in CONNECTED state and reporting of the measurements to eNB/RNC available at the time of reporting condition.
Where UE log in idle mode together with time stamps and optionally with accurate location information.
Requirements for minimization of drive test
Minimization of drive test should follow the following requirements.
UE measurement configuration
The operator can bale to configure an UE measurements for logging purpose independent from the NW configurations. This is done for Radio Resource Management (RRM) purpose.
UE measurement collection and reporting
The time interval for measurement logs collection and reporting shall be configurable in order to limit the UE battery consumption and network load.
Geographical scope of measurement logging
This requirement says that the operator should able to configure the geographical area where the defined set of measurement can be performed.
The measurements in the measurement logs should be connected to the location information.
The measurements in measurement logs shall be linked to the time stamp available in the UE.
Device type information
The terminal type and the capabilities of the UE should be correctly indicated to the NW so that the operator can select correct terminals for specific measurements.
Dependency on Self Organizing Network (SON)
The solutions for minimization of drive test shall be able to work independently from the SON support in the network.
- 3GPP TR 36.805 – Study on Minimization of drive-tests in Next Generation Networks
- 3GPP TS 37.320 – Universal Terrestrial Radio Access (UTRA) and Evolved Universal Terrestrial Radio Access (E-UTRA); Radio measurement collection for Minimization of Drive Tests (MDT); Overall description; Stage 2 (Release 10)