Scope
Since 3G, mobile networking standards are being standardized by 3GPP, enabling true world-wide interoperability. Currently, 3GPP is further developing the 5G standard – “beyond 5G” (B5G) – and starting to develop the 6G standard. Energy efficiency is increasingly becoming a topic within 3GPP. This summary discusses ongoing energy efficiency related efforts aimed at releases 19 and 20.
Summary
Up to Release 18, 3GPP was internally focused with regards to energy efficiency, that is its goal was to satisfy user experience (i.e. to provide optimal network performance), while at the same time achieving energy efficiency within the network e.g., to reduce network operators’ operational expenditure.
Release 19
Starting from Release 19, energy efficiency is also being considered as service criteria. This means that customers (end users and verticals), can include energy efficiency as criteria for consuming services, next to other, more traditional, network performance parameters. Consequently, the mobile network may play a role in end-to-end energy optimisation scenarios as targeted by EXIGENCE.
As usual, within 3GPP, this work started by defining use cases and requirements within 3GPP SA1, as part of a dedicated study item. The outcome of this work has been documented in a technical report, TR 22.882. Subsequently, the (consolidated) requirements of this effort have been included in Section 6.15a of TS 22.261. The complete specification document TS 22.261 includes all service requirements for the 5G system (in this case for Release 19), and requirements for energy efficiency as service criteria are now included. In the meantime, this work was picked up by 3GPP SA2, which is now performing their own study with regards to energy efficiency as service criteria. The goal of that study is to identify the key technical issues to be solved and to propose solutions to solve them. The results of this (ongoing) work are documented in another technical report, TR 23.700-66.
The requirements stated in Section 6.15a of TS 22.261 address the following topics:
- Subscription policies that define a maximum energy credit limit for services without QoS criteria (i.e., best-effort services), including associating energy consumption information with charging information.
- Selection of an application server from a set, based on energy related information.
- Modifying a communication service based on energy related information based on subscription policies.
- Operating (part) of the network according to energy consumption requirements based on subscription policies or requested by an authorised 3rd
- Support for different energy states of network elements and functions, which may change dynamically, and involve different charging mechanisms.
- Monitoring of energy consumption, and associated network performance statistics, per network slice and per subscriber, as well as per service consumed by that subscriber. Specifically, the 5GS may provide monitoring for serving a 3rd party, subject to an agreement with such 3rd Note that energy monitoring is done by means of averaging or applying a statistical model and does not imply some form of ‘real time monitoring’.
- Exposing such energy consumption, prediction on energy consumption, and associated network performance statistics to a 3rd party, and enabling authorized 3rd parties to obtain information related to abovementioned credit limit and to configure which information should be exposed. Also, the 3rd party shall be able to provide current or predicted energy consumption information (note, that the ratio of renewable energy and carbon emission information are also in scope).
Internal network optimisation, taking energy and network load information into account, for a specific area and timeframe. In particular, this is about inter-MNO (inter-PLMN and/or also involving NPN) optimisation, where one MNO can provide service for others at times of low usage. Similarly, regulators could ask for such coordination in case of temporal energy shortage.
According to TR 23700-66, 3GPP SA2 is currently working on solutions addressing the following key issues:
- Network energy related information exposure. This is about whether and what information can be exposed and at what granularity, how this information can be exposed, and what information must be obtained from various network entities to achieve that.
- Subscription and policy control to support energy efficiency and energy saving as service criteria. This is about whether and how to enhance the existing subscription and policy control framework, and whether and how these enhancements will impact charging.
5GS enhancements for network energy saving and efficiency. This is about whether and how to enhance the existing operations and procedures, whether and how to enhance NF (re)selection, whether and how to enhance network analytics and what, if any, energy related information (e.g., per QoS flow/PDU session/UE/NF) is required and how it is collected.
Release 20
Recently, 3GPP SA1 has agreed upon a new study item on energy service as service criteria to extend the work that was started in Release 19. This study item was initially proposed by China Mobile and supported and adjusted by TNO and Telefonica on behalf of EXIGENCE, in order to create sufficient maneuvering room for submitting use cases and requirements derived from EXIGENCE work in T2.1. Specifically, there are opportunities to submit use cases before the May and August SA1 meetings. It is expected that the work will follow a similar trajectory as Release 19 (i.e., in the next phase SA2 will again be identifying key issues and proposing solutions). This provides another opportunity for EXIGENCE to influence the 3GPP standard.
The ongoing work in Release 19 only considers best-effort service, with policies to limit energy consumption. In contrast, the current study should also investigate services with stringent QoS requirements, in order to determine to which extent, they could take into account energy service criteria as well (e.g., user preferences or operator policies) and/or be impacted by energy availability limitations.
Relevance for EXIGENCE
The use cases and requirements defined for R19 (TR 22.882, TS 22.261, 6.15a) are relevant to requirements and scenarios, in order to build on top of existing ideas (e.g., expand to a multi-domain setting), rather than duplicate them. The ongoing work on key issues and solutions (TR 23.700-66) is relevant to energy metrics, energy measurements, data collection, resource interconnectivity, orchestration, and energy optimisation. The document is still in progress and therefore might also provide an outlet for EXIGENCE work – standardisation –, even though the time horizon is probably too short. The work planned within R20 is a continuation of the R19 work and therefore bears relevance to the same tasks: it should be monitored on behalf of requirements and scenarios, energy metrics, energy measurements, data collection, resource interconnectivity, orchestration, and energy optimisation, but more importantly it provides an opportunity to contribute to standardisation.
