Capacity and Coverage Optimization Monitor Function

Description

The CCO Monitor Function is a component of the Capacity and Coverage Optimization (CCO) feature within the 3GPP Self-Organizing Network (SON) framework. CCO aims to automatically adjust network parameters to optimize capacity and coverage, improving user experience and network efficiency. The CCO Monitor Function is responsible for observing and analyzing the effects of CCO actions. It collects data such as performance counters, UE measurements, and alarms to assess whether the CCO adjustments are achieving the desired goals or if they are causing unintended issues. This function is defined in 3GPP TS 28.628 (SON management) and TS 32.522 (performance management).

In the SON architecture, CCO is typically implemented as a control loop: the CCO function (e.g., in the Element Manager or Network Manager) makes adjustments to network parameters (e.g., antenna tilt, transmit power) based on input from the CCO Monitor Function. The monitor function provides the necessary feedback by continuously evaluating key performance indicators (KPIs) such as call drop rate, handover success rate, cell edge throughput, and coverage holes. It may also use UE measurement reports (e.g., RSRP, RSRQ) to detect coverage problems. If the monitor function detects degradation, it can trigger alarms or initiate corrective actions, potentially reverting the CCO changes.

The CCO Monitor Function is not a standalone network node but a logical function that can reside in various management entities, such as the Domain Manager (DM), Element Manager (EM), or Network Manager (NM). It interacts with the CCO function and other SON functions through standardized interfaces (e.g., Itf-N). The monitoring data is often aggregated and stored in the Performance Management (PM) system, where it can be analyzed over time. The function may also correlate data from multiple sources to distinguish between CCO-induced effects and other factors (e.g., traffic variations, equipment failures).

The definition of the CCO Monitor Function has remained essentially unchanged from Rel-10 to Rel-19, with only minor formatting differences in the quoted text. This stability reflects the maturity of the SON concept and the fact that the fundamental monitoring requirements have not changed. However, the implementation of CCO and its monitoring has evolved with new radio technologies (LTE, 5G) and more advanced SON features, such as centralized SON (C-SON) and distributed SON (D-SON). In 5G, the CCO Monitor Function may be integrated into the Management Data Analytics Function (MDAF) or the Network Data Analytics Function (NWDAF) for more sophisticated analytics.

Overall, the CCO Monitor Function is crucial for ensuring that automated capacity and coverage optimization does not degrade network performance. It provides the necessary oversight and feedback to make SON reliable and trustworthy, reducing the need for manual intervention while maintaining network quality.

Purpose & Motivation

The CCO Monitor Function exists to provide oversight and feedback for automated Capacity and Coverage Optimization (CCO) in mobile networks. Before SON, network optimization was a manual, labor-intensive process where engineers would analyze drive tests and performance reports to adjust parameters. This was slow and could not keep up with dynamic network conditions. SON introduced automation, but automated adjustments can sometimes have unintended consequences, such as creating coverage gaps or interference. The CCO Monitor Function was created to monitor the effects of CCO actions and ensure they are beneficial, thus enabling safe automation.

Historically, CCO was one of the first SON use cases standardized in 3GPP Release 10. The need for a monitor function arose from the realization that CCO algorithms must be validated in real-time. The monitor function collects performance data and alarms to detect if CCO changes cause problems. If issues are detected, the CCO function can be alerted to revert or adjust the changes. This closed-loop approach is essential for reliable SON operation.

The CCO Monitor Function also addresses the challenge of distinguishing between the effects of CCO and other factors. For example, a drop in throughput could be due to increased traffic, not a bad CCO decision. By correlating multiple data sources, the monitor function can make this distinction. This prevents unnecessary reversions and ensures that CCO can operate effectively. The function has remained relevant through subsequent releases, evolving to support new technologies like 5G, where it may leverage advanced analytics. Its existence underscores the importance of monitoring in any automated network management system.