Description
Minimization of Drive Tests (MDT) is a network management and optimization feature standardized across 3GPP releases. Its core function is to automate the collection of radio measurements, location information, and other relevant data from participating User Equipment (UE) and evolved NodeBs (eNBs/gNBs) in a controlled manner. This data is then reported to the network management system (NMS) or trace collection entity for analysis. MDT transforms passive UEs into active network probes, providing a detailed, real-world view of network performance, coverage, and quality of service (QoS) from the end-user perspective.
Architecturally, MDT involves several key network elements. The Management System (e.g., OAM) configures MDT tasks, specifying what measurements to collect (e.g., Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), throughput), under what conditions (immediate or logged), and from which UEs (based on area, subscription, etc.). This configuration is communicated to the Radio Access Network (RAN) via the Itf-N interface (between OAM and RAN) or within the RAN. The RAN node (eNB/gNB) then activates MDT for selected UEs via RRC signaling. UEs perform the requested measurements, which can be reported immediately (Immediate MDT) or stored locally and reported later when connected (Logged MDT). Location information can be obtained via UE-based GNSS, network-based positioning, or RF fingerprinting. The collected MDT reports are ultimately aggregated in the Network Management System for processing and analysis.
MDT works in two primary modes: Immediate MDT and Logged MDT. Immediate MDT is performed by UEs in RRC_CONNECTED state, with measurements reported directly to the network. This is useful for real-time troubleshooting. Logged MDT is performed by UEs in RRC_IDLE or RRC_INACTIVE states; measurements are stored in an internal log with timestamps and location info (if available) and reported when the UE transitions back to RRC_CONNECTED. This mode is invaluable for coverage optimization, especially in areas with poor connectivity. The data collected provides insights into coverage holes, pilot pollution, handover failures, and QoS degradation, enabling data-driven network planning and optimization.
Purpose & Motivation
MDT was created to address the significant operational expenditure (OPEX) and limitations associated with traditional manual drive testing. Manual tests are costly, time-consuming, provide only a snapshot in time, cannot cover all geographical areas (e.g., indoors, private property), and lack the end-user context for data services. As networks grew denser and more complex with 3G and 4G, these limitations became increasingly burdensome for operators striving to maintain high service quality.
The technology solves the problem of inefficient and incomplete network performance monitoring by leveraging the existing fleet of user devices as distributed sensors. This provides continuous, large-scale, and user-centric data that reflects the actual service experience. It enables proactive network optimization, faster fault detection, and more accurate capacity planning. Historically, MDT was introduced in 3GPP Release 9 for LTE and later extended to UMTS, GSM, and NR, becoming a cornerstone of Self-Organizing Network (SON) functionalities.
MDT addressed the key limitation of previous approaches—the lack of scalable, ubiquitous measurement collection—by standardizing the procedures for UE-based measurement gathering and reporting. This allowed operators to move from reactive, sample-based optimization to a data-driven, continuous optimization paradigm. It was motivated by the industry's push towards automation (SON) and the need to manage increasingly heterogeneous and dense networks cost-effectively.
Classification
Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (84 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the MDT function was expanded to include the collection of Bluetooth and WLAN measurements. This new capability required introducing support for these measurements across key interfaces, specifically in the S1AP and X2AP protocols. The changes were documented and refined in the overarching MDT specification, 3GPP TS 37.320.
- Introduction of Bluetooth and WLAN measurement collection in MDT TS 36.331CR3342
- CR to S1AP to introduce Bluetooth and WLAN measurement in MDT TS 36.413CR1617
- 37.320 CR to introduce BT and WLAN in MDT TS 37.320CR0071
- Correction on Bluetooth and WLAN measurement collection in MDT TS 36.331CR3651
- MDT correction TS 36.413CR1571
- CR to X2AP to introduce Bluetooth and WLAN measurement in MDT TS 36.423CR1231
In Release 16, the MDT function was significantly expanded to introduce full support for 5G New Radio (NR), including specific NR MDT requirements and configurations. Key enhancements included enabling MDT for UEs in the inactive state and providing support for E-UTRA-NR Dual Connectivity (EN-DC) deployments. Furthermore, the release involved aligning and correcting procedures across both LTE and NR, such as transitioning from area-based to management-based MDT.
- Update MDT requirement to include support of MDT in 5G TS 32.421CR0091
- Add MDT business level requirements TS 32.421CR0092
- Add MDT requirements for NR TS 32.421CR0093
- CR on enhancements on LTE MDT and SON TS 36.331CR4218
- MDT support for EN-DC TS 36.413CR1747
- MDT support for EN-DC TS 36.423CR1440
+ 24 more changes
In Release 17, key enhancements for MDT included the introduction of an event-based trigger for LTE MDT logging, allowing measurements to be collected based on specific network events. Furthermore, the release introduced the reporting of height information in MDT reports, providing more precise location data for network optimization. These additions were complemented by various corrections and alignment efforts to support the overall MDT enhancement.
- Add some additional MDT requirements TS 32.421CR0096
- Introduction of event-based trigger for LTE MDT logging [LTE-Event-MDT] TS 36.304CR0834
- Introduction of event-based trigger for LTE MDT logging [LTE-Event-MDT] TS 36.331CR4752
- On introducing height information reporting in MDT reports [LTE-Height-MDT] TS 36.331CR4756
- Correction of LTE MDT on event trigger logging [LTE-Event-MDT] TS 36.413CR1899
- Correction of LTE MDT on Sensor information[LTE-Height-MDT] TS 36.413CR1901
+ 18 more changes
In Release 18, MDT enhancements were introduced to support Non-Public Networks (NPN), including both SNPN and PNI-NPN deployments. The release also added a "Report Amount" configuration for specific E-UTRAN measurements (M4, M5, M6, M7) to control data volume and defined an indicator for MDT configuration in Multi-Radio Dual Connectivity (MR-DC) scenarios. Furthermore, it included corrections and clarifications for existing MDT procedures, such as those for Immediate MDT and logged MDT reporting.
- TS 32.421 Requirements for MDT in NPN TS 32.421CR0107
- CR to 36331 for introducing SON/MDT features in Rel-18 TS 36.331CR4973
- Introducing Report Amount for M4, M5, M6, M7 measurements for E-UTRAN [ReportAmount_MDT_E-UTRAN] TS 36.413CR1876
- Introducing Report Amount for M4, M5, M6, M7 measurements for E-UTRAN [ReportAmount_MDT_E-UTRAN] TS 36.423CR1688
- Introduction of MDT enhancements to support Non-Public Networks TS 37.320CR0128
- Introduction of Rel-18 MDT enhancements TS 37.320CR0129
+ 10 more changes
In Release 19, the MDT function was enhanced with new support for Non-Terrestrial Networks (NTN) and network slicing, alongside corrections and clarifications for existing features. A major addition was the introduction and architectural support for **Continuous Management-based MDT**, including in split architecture deployments. The release also included miscellaneous updates for SON-MDT and corrections to the numbering of C-MDT requirements and the propagation of MDT configuration.
- Rel-19 CR TS 32.421 Continuous MDT TS 32.421CR0148
- MDT enhancement for NTN TS 37.320CR0144
- Rel-19 CR TS32.421 Correct C-MDT requirements numbering TS 32.421CR0149
- Corrections on MDT for slicing TS 37.320CR0147
- Support for Continuous management-based MDT TS 37.320CR0151
- Miscellaneous and non-controversial changes for SON-MDT TS 38.331CR5662
+ 2 more changes
Explore further
Broader topics and technologies where MDT plays a role.
Defining Specifications
3GPP specifications that define or reference MDT, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TS 25.123 vj00 | Radio Resource Management for TDD | Rel-19 |
| TS 25.133 vj00 | UTRAN RRM Requirements for FDD | Rel-19 |
| TS 25.304 vj00 | UTRA Idle Mode Procedures Specification | Rel-19 |
| TS 25.331 vj00 | UTRAN RRC Protocol Specification | Rel-19 |
| TS 25.401 vj00 | UTRAN Overall Architecture | Rel-19 |
| TS 25.410 vj00 | Iu Interface Introduction for UTRAN | Rel-19 |
| TS 25.413 vj00 | Radio Access Network Application Part (RANAP) | Rel-19 |
| TS 25.423 vj00 | UTRAN RNSAP Specification | Rel-19 |
| TR 26.909 vj00 | QoE Enhancement for Streaming Services | Rel-19 |
| TS 28.536 vj20 | Management services for communication service assurance | Rel-19 |
| TS 28.628 vj00 | SON Policy NRM IRP Information Service | Rel-19 |
| TR 28.837 vi00 | Technical Report on Trace/MDT Management | Rel-18 |
| TS 29.552 vj40 | 5G Network Data Analytics Signalling Flows | Rel-19 |
| TS 32.130 vj20 | Network Sharing OAM&P Requirements | Rel-19 |
| TS 32.421 vj30 | Subscriber & Equipment Trace Concepts & Requirements | Rel-19 |
| TS 32.422 vk00 | Telecom Management: Trace Control & Configuration | Rel-20 |
| TS 32.441 vj00 | Trace Management IRP Requirements | Rel-19 |
| TS 32.442 vj00 | Trace Management IRP: Information Service | Rel-19 |
| TS 32.446 vj00 | Trace Management IRP Solution Set Definitions | Rel-19 |
| TS 32.827 va10 | UE Management over Itf-N for MDT/SON | Rel-10 |
| TS 32.851 vc20 | Network Sharing OAM Requirements | Rel-12 |
| TS 33.128 vj50 | 3GPP TS 33.128: Lawful Interception Protocols | Rel-19 |
| TS 33.849 ve00 | 3GPP Privacy Principles and Guidelines | Rel-14 |
| TS 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 36.304 vj00 | UE Idle Mode Procedures in E-UTRA | Rel-19 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 36.413 vj10 | S1 Application Protocol (S1AP) | Rel-19 |
| TS 36.423 vj10 | X2 Application Protocol (X2AP) Specification | Rel-19 |
| TS 36.887 vc00 | Energy Saving Enhancement for E-UTRAN Study | Rel-12 |
| TS 37.320 vj00 | Minimization of Drive Tests (MDT) Overview | Rel-19 |
| TS 37.816 vg00 | RAN-centric Data Collection & Utilization Study | Rel-16 |
| TS 38.331 vj00 | NR Radio Resource Control (RRC) Protocol Specification | Rel-19 |
| TS 38.401 vj10 | NG-RAN Architecture Specification | Rel-19 |
| TR 38.890 vh00 | NR QoE Management and Optimization | Rel-17 |
