Data Description Method

Description

The Data Description Method (DDM) is a core component of the 3GPP Performance Management (PM) architecture, specified primarily in the 32-series of technical specifications. It provides a standardized, technology-independent language for defining the structure and meaning of performance measurement data. A Data Description (DD) is a formal, machine-readable document that precisely specifies performance metrics, including their names, data types, units, allowed values, and semantic definitions. DDs are used to configure Performance Measurement (PM) data collection in Network Elements (NEs) and to interpret the collected data files (PM data files) generated by those elements.

Architecturally, DDM operates within the framework defined by the Integration Reference Point (IRP) for Performance Management. The IRP defines the information model and northbound interfaces (like Itf-N) used by Operations Support Systems (OSS) to manage network elements. DDM provides the concrete syntax and semantics to instantiate this information model for specific measurement types. A key component is the Data Description Language (DDL), which is used to author DDs. These DDs are then deployed to both the network elements (which use them to format output data) and the OSS (which uses them to parse and understand the incoming data streams). This ensures that the producer (NE) and consumer (OSS) of performance data have a shared, unambiguous understanding of the data's content.

The method works by separating the definition of *what* is measured from the implementation of *how* it is measured. Network equipment vendors implement the measurement collection according to the rules in the DD. The output is structured data files (e.g., XML or ASN.1 encoded) whose schema is directly derived from the DD. This decoupling is vital for interoperability. For an OSS to process PM files from a new network element or a new release, it only needs the corresponding DD file, not new parsing code for every vendor or release. DDM covers a wide range of performance data, including counter measurements, gauge measurements, status inspections, and complex derived measurements, supporting the comprehensive monitoring required for 2G, 3G, 4G, and 5G networks.

DDM's role is foundational for automated network performance management. It enables multi-vendor, multi-technology networks to report performance data in a consistent manner. This consistency is a prerequisite for effective fault management, service assurance, capacity planning, and network optimization tasks performed by the OSS. By providing a rigorous, standardized description language, DDM reduces integration costs, minimizes errors in data interpretation, and facilitates the development of generic OSS applications that can work with performance data from any compliant network element.

Purpose & Motivation

DDM was created to solve a fundamental problem in telecommunications network management: the lack of a standardized, vendor-neutral way to define and exchange performance measurement data. Before its introduction in 3GPP Release 6, network equipment vendors often used proprietary formats and definitions for performance counters and metrics. This created significant integration challenges for network operators who deployed multi-vendor networks. An operator's OSS required custom parsers and adapters for each vendor's equipment, leading to high integration costs, prolonged deployment cycles, and a high risk of misinterpretation of data due to ambiguous definitions.

The primary motivation was to enable true interoperability in the performance management domain. By defining a formal description method, 3GPP aimed to decouple the data definition from the data transport and the OSS applications. This allows vendors to innovate in their measurement collection implementations while guaranteeing that the output data can be universally understood. The historical context was the increasing complexity of 3G networks and the industry's push towards standardized, open management interfaces as part of the Telecom Management Network (TMN) and later the NGOSS (Next Generation Operations Systems and Software) frameworks. DDM directly addresses the limitations of ad-hoc, bilateral agreements on data formats by providing a single, authoritative source of truth for performance metric semantics.

Furthermore, DDM supports the evolution of network technology. As 3GPP introduced new radio access technologies (HSPA, LTE, NR) and core network architectures (EPC, 5GC), the performance management framework needed to be extended without breaking existing systems. DDM provides the extensibility to define new measurements for new network functions and services while maintaining backward compatibility. It solves the problem of scaling network management for increasingly heterogeneous and software-defined networks, ensuring that performance data remains a reliable source for autonomous network optimization and AI/ML-driven operations.

Key Features

• Standardized Data Description Language (DDL) for defining performance metrics
• Technology-independent framework applicable to 2G, 3G, 4G, and 5G network elements
• Enables unambiguous semantic definition of counters, gauges, and status inspections
• Decouples data production in Network Elements from data consumption in the OSS
• Supports the generation of interoperable PM data files (e.g., XML format)
• Facilitates automated configuration of performance data collection via IRP interfaces

Evolution Across Releases

Defining Specifications