Energy state

Description

Energy state is a concept introduced in 3GPP Release 19 to formally characterize the energy-related condition of a cell, a network element (NE), or a network function (NF). It provides a standardized way to represent whether a network entity is in an energy-saving mode or in a normal operational mode. This state is defined in TS 28.310, which specifies energy efficiency management for 5G networks. The energy state is crucial for enabling energy-efficient network operations, allowing operators to dynamically manage power consumption based on traffic load, energy costs, and environmental considerations.

The energy state can be applied to various levels of the network architecture. At the cell level, it indicates whether a cell is active, in a sleep mode, or in a transitional state. At the network element level, it reflects the overall energy mode of a physical node, such as a gNB or a base station. At the network function level, it describes the energy-related status of a virtualized or cloud-native function, such as an AMF or SMF. The state is managed through the management plane, using protocols such as NETCONF/YANG or RESTful APIs, as specified in 3GPP management standards.

The concept of energy state is closely tied to energy saving features in 5G, such as cell DTX/DRX, advanced sleep modes, and carrier shutdown. These features allow the network to reduce energy consumption during low traffic periods by deactivating certain components or entire cells. The energy state provides a unified way to report and control these features, ensuring interoperability between different vendors and management systems. It also supports energy efficiency KPIs, such as energy consumption per unit of traffic, which are essential for monitoring and optimizing network energy usage.

In terms of architecture, the energy state is part of the Management Data Analytics (MDA) and Energy Efficiency (EE) management framework. The network management system (NMS) or element management system (EMS) can query the energy state of network entities and trigger transitions between states based on policies. For example, if traffic in a certain area drops below a threshold, the NMS can instruct a cell to enter an energy-saving state, reducing its transmit power or shutting down some carriers. Conversely, when traffic increases, the cell can be transitioned back to a normal state to maintain service quality.

The introduction of energy state in Rel-19 reflects the growing importance of energy efficiency in 5G and beyond. With the proliferation of IoT devices, densification of networks, and the need to reduce operational expenditure (OPEX) and carbon footprint, energy state provides a standardized mechanism for managing energy consumption. It also aligns with broader industry initiatives, such as the GSMA's Energy Efficiency Benchmarking and the ITU's focus on sustainable networks. As networks evolve towards 6G, the concept of energy state is expected to become even more granular and dynamic, potentially incorporating AI/ML-based predictions and real-time optimization.

Purpose & Motivation

The energy state concept was created to address the lack of a standardized representation of energy-related conditions in 5G networks. Prior to Rel-19, energy saving mechanisms were vendor-specific and lacked interoperability, making it difficult for operators to manage multi-vendor networks efficiently. The energy state provides a common language for describing whether a network entity is in an energy-saving mode, enabling consistent management and automation across different vendors and domains.

Another motivation is the increasing pressure on mobile operators to reduce energy consumption and operational costs. Energy costs constitute a significant portion of OPEX for operators, and with the rise of 5G and the expected densification, this is set to increase. By defining energy states, 3GPP enables operators to implement dynamic energy-saving policies that adapt to traffic patterns, energy prices, and environmental conditions. This not only reduces costs but also supports sustainability goals.

Furthermore, the energy state concept facilitates the integration of energy efficiency into network slicing and service-level agreements (SLAs). For instance, a network slice could be associated with a specific energy state policy, ensuring that the slice's energy consumption meets certain criteria. This is particularly relevant for vertical industries that prioritize sustainability. Overall, the energy state is a key enabler for the vision of a sustainable, energy-efficient 5G network.