This is the second part of the Minimization of Drive Test series. If you missed the first part check you can get it here.
In this part the main focus on different use cases where MDT can be applied.
Minimization of Drive Test (MDT) specifies different ways to improve network efficiency by using UE measurement logs. The logs collection in UE can be periodic or event triggered (e.g Radio Link Failures).
To make the MDT process more efficient and provide adequate results, different use cases are defined.
Information about radio coverage is essential for network planning, network optimization and Radio Resource Management parameters optimization.
The coverage optimization of the network is required in the following cases.
Deployment of new base stations cells
When new base stations or cells are deployed, drive tests are performed before and after the service deployment. When initially the radio waves are transmitted the cell is barred from normal use. (This is done through setting barred information in SIB 3).
But after the initial tests are over and the cell is made available for normal use, the operators does drive test to collect more extensive data of UL/DL coverage measurement to make sure the location under test provides goof UL/DL coverage.
Construction of new highways, railways or major buildings
Areas where new highways / railways / major buildings are constructed are potential areas which residing population will increase, and are important areas to provide good coverage. Also, such large constructions normally introduce weak pilot areas as they become new sources of shadowing losses.
Customer’s complaints are an important trigger to perform drive tests. When customers indicate coverage / throughput concerns (e.g. poor DL coverage at their home, office, etc.), operators perform “drive tests” in the relevant area to observe the coverage quality.
Periodic drive tests
This is the additional phase of drive test that is performed for a particular cell / smaller network area or the entire network in a regular and on demand manner.
Information about mobility problems or failures can be used to identify localized lack of coverage or the need to adapt the network parameters setting, e.g. in order to avoid too early or too late handover and to improve the handover success rate and overall network performance.
The operator needs to be able to determine if there is too much/little capacity in certain parts of the network i.e. to detect locations where e.g. the traffic is unevenly distributed or the user throughput is low. This helps to e.g. determine placement of new cells, configure common channels and optimize other capacity related network parameters.
Parametrization of common channels
User experience and/or network performance can be degraded by suboptimal configuration of common channels (e.g. random access, paging and broadcast channels).
This aspect is important also in the initial deployment of a new radio access technology, in order to check if the quality of service experienced by the end user is in line with the performance target defined in the planning strategy and more in general to test the overall performance of the technology along the subsequent deployment phases.
In the coming parts there will be some more articles on Minimization of Drive Test, the patents related to the technology and what can be the future of this.
- 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)