Key Quality Indicators

Description

Key Quality Indicators (KQI) are a fundamental component of the 3GPP management framework, specifically within the domain of service and resource assurance. They are defined as quantifiable measures that reflect the quality of a specific service as perceived by the end-user. Unlike lower-layer performance counters (KPI - Key Performance Indicators), which monitor network element health (e.g., cell availability, throughput), KQIs are derived metrics that translate technical network performance into service-level quality. They are typically calculated by aggregating and correlating multiple KPIs and other data sources, often using defined formulas or models specified in 3GPP standards.

The architecture for KQI management involves several functional entities. The Network Resource Model (NRM) provides the managed object definitions. The Management Data Analytics Function (MDAF) or other analytics engines can be employed to process raw measurement data (PM - Performance Measurement) and KPIs to compute the KQIs. These KQIs are then exposed to network management systems (NMS/OSS) and service management systems for visualization, reporting, and triggering corrective actions. The definition of a KQI includes its name, a precise formula for calculation, the measurement method, the collection period, and the associated thresholds that define acceptable, degraded, and critical service states.

KQIs are defined per service type. For example, for a Voice over LTE (VoLTE) service, critical KQIs include Call Setup Success Rate, Call Drop Rate, and Mean Opinion Score (MOS) for speech quality. For a streaming video service, KQIs would include Video Playback Success Rate, Initial Buffering Time, and Re-buffering Ratio. By monitoring these service-centric metrics, operators can proactively identify quality degradation, perform root cause analysis by drilling down to the contributing KPIs, and ensure that Service Level Agreements (SLAs) are being met. The standardized nature of KQIs in 3GPP allows for consistent benchmarking and comparison across different network deployments and operators.

Purpose & Motivation

The purpose of Key Quality Indicators is to bridge the gap between pure network-centric performance monitoring and the actual quality experienced by the customer. Traditional network management focused heavily on KPIs like node availability and link utilization, which, while important, did not directly correlate to whether a user could successfully make a high-quality voice call or stream a video without interruption. This disconnect made service assurance and customer satisfaction management challenging.

KQIs were introduced to provide a service-oriented view of network performance. They solve the problem of translating technical metrics into business-relevant quality measures. This allows operators to shift from reactive, network-focused troubleshooting to proactive, service-focused assurance. By defining what 'good quality' means for each service in a quantifiable way, operators can set clear targets, monitor compliance, and prioritize network investments and optimizations where they have the most impact on user perception.

Historically, before widespread KQI standardization, operators developed proprietary service quality metrics, leading to fragmentation and making cross-vendor or cross-operator comparisons difficult. 3GPP's standardization of KQI definitions, calculation methodologies, and management interfaces (e.g., in TS 32.450 series) created a common language for service quality. This was particularly motivated by the evolution to all-IP networks and rich multimedia services (IMS), where the relationship between network conditions and perceived quality became more complex and critical to commercial success.

Key Features

• Service-Centric Measurement: Metrics are defined based on user-perceivable service attributes (e.g., call setup time, video stall rate).
• Derived from KPIs: Calculated by processing and correlating multiple underlying network and element Key Performance Indicators (KPIs).
• Standardized Definitions: 3GPP provides common formulas, collection methods, and thresholds for consistent implementation.
• Hierarchical Structure: KQIs can be aggregated from lower-level service KQIs to higher-level composite service or customer KQIs.
• Threshold-Based Management: Supports configurable thresholds to trigger alarms, reports, and automated corrective actions.
• Integration with Management Systems: Defined interfaces for reporting KQIs to Network Management (NM) and Element Management (EM) systems for service assurance.

Evolution Across Releases

Defining Specifications