Minimization of Drive Test (MDT) Use Case in Mobile Communication


MDT Use Cases

There are various use cases for the operators from the perspective of MDT:

  1.  Coverage optimization
  2.  Mobility optimization
  3.  Capacity optimization
  4.  Parameterization optimization
  5.  Quality of service verification


Coverage Optimization

-It is one of the most important aspects of the network performance which can be directly recognized by the end-user.

-With the help of MDT, it is possible to detect the signal strength and the location of the mobile, which then could be used as a coverage indicator.

-However, the main problem is, that the signal strength between mobiles at the same location and time can differ much more than +- 6dB.

-Another problem is that it is unknown if the mobile is inside the bag or some car which leads to signal loss.

-It logged MDT is used it is not possible to know how if it is not possible to know if it was a network failure or the mobile.

-This type of problem could be solved by collecting many measurement data, which then could be merged and statistically evaluated after that.

-Another problem is that, how to get the location inside the building, it is also suggested to use a GNSS (Global Navigation Satellite System) chip as a location provider.

-There is also a need for good coverage inside big buildings like airports.

-This also requires indoor measurements, but there a GNSS chip is not usable.

-With the help of DT (Drive Testing) and a scanner as a measurement device, it is possible to collect coverage measurements in high quality.

-The problem with this is that it provides only a snapshot of that area, where the DT was executed.


Mobility optimization

-Another use case for optimizing the mobile network is mobility optimization.

-The aim is to have handover failure rates that are as small as possible.

-Handover failure can happen if the mobile and networks do not recognize that the user travels from one cell to another and then as a consequence, the user travels from one cell to another, and then as a consequence that user loses the signal from the old cell.

-Another problem could be that the load is too high and the handover takes too much time.

-In most cases, the call would be dropped.


Capacity Optimization

-For network capacity planning, the operator is interested in the DL (Downlink) and UL (Uplink) throughput and data volume, e.g. to deploy an additional pico cell.

-In 3GPP (3rd Generation Partnership Project) Rel -11, the throughput and volume measurement at MDT were also addressed.

-MDT allows for measuring throughput at the RAN (Radio Access Network).

-A difference to drive tests is also that MDT uses ordinary user traffic and drive tests applications with known traffic characteristics. 

-With large data blocks the results are limited by the transmission medium.

-With help of MDT it is possible to measure the amount of traffic within a cell.

-The location of the sending UE (User Equipment) is stored together with the measured data volumes.


Parameterization Optimization

-The sub-optional configuration of common channel parameters (random access, paging, and broadcasting channels) can degrade the network performance.

-For instance, the UE (User Equipment) monitors the paging channels, which are needed to react to the incoming calls.

-If now the information cannot be decoded, the UE is not reachable for other calls.  

-The operators only find out about problems with the common channels, when they receive customer complaints.


Quality of Services (QoS) Verification

The verification of QoS is another important use case.

-It is not only the coverage that affects the user experienced QoS, but also the scheduling principle for packet type connections which is defined by the operator.

-The high degree of algorithm flexibility leads to different performance.

- It is difficult to estimate the QoS from radio measurements such as coverage, path loss, or coverage interference.

- A benefit of the MDT throughput measurement is that real user traffic is used and no additional load on the network is produced.

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