Improvements in and relating to energy usage in a telecommunication network

Abstract

An Application Function, AF is used to acquire energy information from an Energy Information Function, EIF, by issuing a subscription request to the EIF, via a Network Exposure Function, NEF; and the EIF responding, if authorised, with a confirmation; and the EIF further providing to the AF, via the NEF, energy information. This may allow energy consumption information to be provided at the UE, Protocol Data unit or quality of service level, and requests for session resources to be made and a desired energy saving profile to be used according to energy credit and savings levels, and subscription and unsubscribe requests to be made.

Description

The present invention relates to enhancements to subscriptions and policy control for supporting energy efficiency and energy saving in a telecommunication network. Currently, there are more than 110 countries committed to a net zero emissions target by 2050. The Paris Agreement attempts to ensure global temperatures stay within 2C by 2100, but preferably closer to 1.5C. The motivation of reducing energy emissions and increasing the energy efficiency of the telecoms sector is more urgent than before. Also, considering that the price of energy is going up, and the increasing traffic load of telecoms systems, mobile network operators are keen to optimize the costs of ongoing operations (opex). Energy-saving measures in network operations are necessary for New Radio (NR) equipment and other components of telecommunications systems. Compared to previous generations, the 5G New Radio (NR) offers a significant energyefficiency improvement in its first release (3GPP Rel-15), i.e. cell activation / deactivation over Xn / X2 / F1 interface via coordination between peer eNB / gNBs, sparser RS and SS signals, URLLC, CU / DU architecture and IVIR-DC, etc. However, based on the GSMA report '5G energy efficiencies: Green is the new black’ (https: / / data.gsmaintelligence.com / api-web / v2 / research-file-download?id=54165956&file=241120-5G-energy.pdf) published in 2020, Network opex tends to account for around e.g. 25% of Verizon’s cost base, or 10% of revenue. In addition, over 90% of network costs are spent on energy, consisting mostly of fuel and electricity consumption. To further reduce energy consumption, and improve the efficiency of the 3GPP system, in releases later than Rel-15, some of the working groups (WGs) in RAN, SA and CT have completed or are developing mechanisms to increase energy saving or energy efficiency. To reduce the energy consumption of the Radio Access Network (RAN) part, in Rel-18, RAN WG started to study and specify the techniques on network energy savings (RAN WID in RP-223540 / RP-230566 Sept. 2023), and RAN will further work on network energy saving improvement in Rel-19 (RP-234065) on supporting on-demand SSB SCell operation for UEs in connected mode, on-demand SIB1 for UEs in idle / inactive mode, and adaptation of common signal / channel transmissions. SA5 started their work on Energy efficiency of the 5G system in Rel-16. In Rel-17 (TR 28.813 -Study on new aspects of Energy Efficiency (EE) for 5G) and Rel-18 (TR 28.913), SA5 extended its scope from RAN only to the whole 5G system. The specified techniques are documented in TS 28.310 ‘Management and orchestration; Energy efficiency of 5G’ and the corresponding KPIs and measurements related to Energy efficiency (EE) are documented TS 28.552 'Management and orchestration; 5G performance measurements’ and TS 28.554 ‘Management and orchestration; 5G end to end Key Performance Indicators (KPI)’. In Rel-19, SA5 will keep working on energy efficiency and energy saving aspects of 5G networks and services according to the SID approved in SP-231723 in Dec 2023. SA1 is currently working on the potential requirements and solutions on Rel-19 Energy Efficiency as a service criteria (acronym: EnergyServ). This topic is due to be 100% completed by TSG 102 (Dec, 2023). The outcome of the study phase is documented in TR 22.882 - Study on Energy Efficiency as service criteria). And some of the specified SA1 stage 1 requirements, e.g. the max. energy credit, might be down streamed to SA2 for further stage 2 work. In the previous releases of NR (earlierthan Rel-19), the studies concentrated more on howto satisfy user experience and try to achieve energy efficiency at the same time. The use cases and solutions basically concern enhancements within the 3GPP network. For example, requirements for energy efficiency have been introduced by SA1 to clause 6.15 of TS 22.261 as a fundamental 5G system requirement. However, those requirements more focused on the optimization of UEs battery life based on network configuration and control, including the UEs using small rechargeable and single coin cell batteries. But the verticals (diverse industry sectors' service providers) and customers have no approach to enhance or improve the energy efficiency for the whole system. SA1 has completed a study on energy efficiency as a service in Rel-19 (TR 22.882), which enables the users to select energy efficiency criteria based on request and some of the network performance parameters is needed. Therefore, in some scenarios, e.g. satellite and terrestrial convenience scenario, the users or operators could choose / request the best way in satisfying both user experience and energy efficiency. At the same time, the network could also deploy the more efficient strategies, i.e. energy-efficient network resource allocation and scheduling. The SA1 work on Energy Efficiency as a service criteria mainly focuses on: • Define and support energy efficiency criteria as part of communication service to user and application services. • Provide information exposure on systematic energy consumption or level of energy efficiency to vertical customers. The conclusions of this study have been captured in the 5G system requirements specification, TS 22.261. These requirements might be addressed by SA2, the system architecture group. SA2 is studying potential solutions to accomplish or satisfy the corresponding SA1 requirements. The consolidated conclusions include but are not limited to the following (in clause 6 of TR 22.882 and clause 6.15a of TS 22.261): • Subject to operator’s policy, the 5G system shall support subscription policies and means to enforce the policy that define a maximum energy consumption rate for services without QoS criteria; • The 5G network shall support a means to define maximum energy consumption rate with specific granularities (which include subscriber granularity, network slice granularity). • Subject to operator’s policy, the 5G system shall support subscription policies that define a maximum energy credit limit for services. The maximum energy credit limit could be used to control the services. • Charging related requirements, i.e. subject to operator’s policy, the 5G system shall support a means to associate energy consumption with charging information based on subscription policies. • The 5G system shall support different energy states of network elements and network functions and dynamic switch between different energy states. • For Monitoring and measurement related to energy efficiency purposes, the 5G network shall support energy consumption monitoring at per network slice and per subscriber granularity, 5G system shall be able to acquire energy consumption information of the network functions serving this 3rd party, 5G system shall be able to acquire the ratio of renewable energy used to provide dedicated communication service to this 3rd party on periodic basis, , the 5G system shall be able to acquire the energy efficiency information (e.g., including the estimated carbon emissions) related to a subscriber based on the subscriber’s data volume over a specific period of time, the operator’s network energy consumption, and the carbon intensity of operator’s network. To improve the energy saving / efficiency and reduce the operation expense of NR system, in R15 and later release, RAN3 introduced energy saving for intra- and inter-system, as described in clause 15.4 of TS 38.300. This function allows the deployment of capacity boosters which provides extra capability on top of the basic coverage. Different from the cell that provides basic coverage, the capacity booster cells could be turned on and off by the NR-RAN node or the O&M autonomously, i.e. based on the load of the cell. The activation status or request of the capacity booster cell will be interacted over Xn interface between the corresponding NG-RAN nodes. The O&M-involved energy saving was specified by SA5 and documented in clause 5.1.3.3 of TS 28.310. In Rel-18, considering the significant operational cost in the radio part, RAN approved the topic - ‘Network energy savings for NR’ in order to optimize the energy consumption and energy efficiency of the radio part. The objectives of RAN WGs include but not limited to the following: • Specify SSB-less SCell operation for inter-band CA for FR1 and co-located cells. • Specify enhancement on cell DTX / DRX mechanism including the alignment of cell DTX / DRX and UE DRX in RRC_CONNECTED mode, and inter-node information exchange on cell DTX / DRX. • Improve energy efficiency or reduce energy consumption via spatial and power domains optimization, i.e. enhancements on CSI and beam management related procedures. • Specify mechanism(s) to prevent legacy UEs camping on cells adopting the Rel-18 NES techniques, if necessary • Specify CHO procedure enhancement(s) in case source / target cell is in NES mode • Specify inter-node beam activation and enhancements on restricting paging in a limited area • Specify the corresponding RRM / RF core requirements, if necessary, for the above features For the above RAN works, 5GC are not involved in either the decision making on energy saving and energy efficiency enhancement or the capacity booster cell activation and deactivation or configuration in the current standards. 3GPP SA5 started the work on ‘Energy efficiency of 5G’ since Rel-16. In Rel-16, SA5 focused on the Energy Efficiency (EE) and Energy saving (ES) of mobile networks. In Rel-17, the SA5 extended the scope from RAN part only to the whole 5G system. EE Key Performance Indicators (KPI) have been defined for the 5G core network, network slices etc. SA5 work focuses on OA&M, i.e. define mechanisms to collect measurements from the 5G Network Functions via OA&M standardized APIs. Performance of network slices has been defined per type of network slice, namely for enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communication (URLLC) and massive Internet of Things (MIoT), whereas user plane traffic volumes have been considered to define the performance of the 5GC. How to measure the energy consumption (EC) of Physical Network Functions (PNF) has been defined by ETSI EE. However how to measure the EC of Virtualized Network Functions (VNF) was blank. In Rel-17, SA5 has defined a method to estimate it, based on the estimated energy consumption of the underlying virtual compute resource instance(s), i.e. Virtual Machine(s) (VM). Currently, SA5 is still working on Rel-18 energy efficiency of 5G. On top of Rel-17, in Rel-18, SA5 is working on more accurate virtual CPU usage measurements from ETSI NFV MANO which could be used to estimate the Energy Consumption of virtual machines, new use cases for Energy Saving in the whole 3GPP system, considerations on digital sobriety etc. In the future releases, some of the parameters and measurement technique / metrics may be further enhanced by SA2 WG to support the system level energy saving and the efficient operation. SA5 also introduced the MDA (Management Data Analytics) assisted Energy Saving in clause 7.2.4 and clause 8.4.4 of TS 28.104. The MDA assisted energy saving is achieved by activating the energy saving mode of the NR capacity booster cell or5GC NFs (e.g. UPF etc.). With considering the energy saving policies setup by the operators, the Management Data Analytics Service (MDAS) producer is able to provide energy saving recommendations to the service consumer to assist with the energy saving decision-making. For example, the MDAS procedure may provide an output to indicate where the energy efficiency issues (e.g. high-energy consumption, low energy efficiency) exist in the system and the cause of the energy efficiency issues based on the request of the consumer. Considering the energy cost is one of the most significant sources of operations costs for Mobile Network Operators (MNOs), there has been increasing work in 3GPP on improving energy efficiency (EE), energy saving (ES) and reducing the energy consumption (EC) of 5GS. In the above clauses, the existing work related to EE, ES and EC in other 3GPP WGs is reviewed. From the network perspective, the previous solutions studied how to optimize energy consumption by adapting the network itself, e.g. activating and deactivating parts of the network including cells, network functions (NFs), etc. Such changes to the topology and components of the network could be either transparent to the network architecture or have implications with the architecture, e.g. reselection of proper network functions. The previous work is more from the perspective of network management, including the OAM and RAN node / cell management; or from the UE perspective. Previous work does not study how to improve and enhance the energy saving and energy efficiency from the system level, i.e. considering the end-to-end energy saving and energy efficiency of a service or UE etc. before R19, standardization work on Enhancement for Energy Efficiency and Energy Saving as Service Criteria for NR system has not been introduced to SA2 before Rel-19. As mentioned abive, stage 1 requirements for energy as a service criteria have been identified by SA1 in the FS_EnergyServ study. Some of the SA1 requirements need to be addressed by SA2, i.e. by introducing new functionalities and mechanisms by SA2. The goal of the SA1 energy efficiency is to provide the same services in a more efficient manner, i.e. the services could be provided in an energy-aware manner with considering the energy use control as service criteria, functional requirements include the ability to control energy use based on operator policies such as 'energy credit limits' and 'maximum energy usage rate' applying to services provided to a UE or group of UEs. Also, SA plenary has issued a 3GPP-wide recommendation on considering Energy efficiency as an important design criterion for the technical solutions 3GPP defines in their specifications (see SP-211621). Therefore, SA2 decided to investigate options for improved system behaviour aimed at energy saving and energy efficiency in Re-19. The SID of SA2 work has been approved in the plenary meeting in SP-231192 (September 2023), including: • WT #1. Study potential framework for network energy consumption exposure. This will include whether and what information is exposed, how it is exposed (e.g., charging) and at what granularity, e.g., at RAN level, Core Network level, network slice level, UE level, PDU session level, and / or QoS flow level. Additionally, whether and how renewable energy or carbon emission information for such granularities can be exposed by an MNO will be studied. • WT #2. Study enhancement for subscription and policy control to enable network energy savings as service criteria. • WT #3. Study 5GS enhancements (e.g., energy usage adjustment for NF from CN aspect, energy saving related decision making, NF selection leveraging NF energy states) for network energy saving including 5GC(NFs) and NG-RAN interactions, analytics, etc. Impacts on the UE are not ruled out e. g., for scenarios specified in TR 22.882 by SA1 EnergyServ. In order to support the above objectives, SA2 study is being carried out between Nov. 2023 to May 2024. For WT#2, the Key Issue (KI) descriptions have been approved in S2-2313823 in SA2 160 meeting in Nov. 2023 and documented in clause 5.2 of TR 23.700-66: 5.2 Key Issue #2: Subscription and policy control to support energy efficiency and energy saving as service criteria 5.2.1 Description Energy related information as service criteria allows delivering services based on e.g., energy related subscriptions and policies to achieve the goal of energy saving. The following aspects will be studied for this key issue: Whether and how to enhance the existing subscription and policy control framework to support energy related information as service criteria, including: Whether and what new energy related UE subscription information are to be defined, and whether and how to use the energy related UE subscription information. Whether and what new energy related policies are to be defined, and how to perform energy related policy control, e.g. to determine, provision and enforce energy related policies. At what granularity (e.g., network slice, UE, NF, PDU Session, QoS flow, application ID, etc.) the energy related policy control can be performed. What network energy related information is required for subscription and policy control and how it is obtained. Whether and how the above enhancements on subscription and policy control will impact charging. NOTE 1: Charging enhancement aspects, if any, are to be addressed in coordination with SA WG5. NOTE 2: The study will address use cases corresponding to the identified requirements as described in clause 6.15a.2 of TS 22.261 [8], The possible enhancements on subscription and policy control depend on the use case. Solutions should identify related use cases which will be addressed. NOTE 3: The potential impact of the enhancements will be evaluated to ensure not to consume more energy than expected to save. The NR policy and charging framework is mainly documented in TS 23.503. The existing policy control could be dived into non-session management related policy control and session management related policy control. The non-session management related policy control mainly include: Access and mobility related policy control, UE policy control, Management of packet flow descriptions, SMF selection management related policy control, etc. The non-session management related network capability could be exposed to the AF from the NEF. Session management related policy control is more referred to PCC (Polices and Charging Control) rules. The basic requirements for the session management related policy control include (in clause 4.3.1 of TS 23.503) but not limited to: • It shall be possible for the PCC framework to base decisions upon subscription information, Access Type and the RAT Type. • A PCC rule may be predefined or dynamically provisioned at establishment and during the lifetime of a PDU Session. The latter is referred to as a dynamic PCC rule. • It shall be possible to take a PCC rule into service, and out of service, at a specific time of day, without any PCC interaction at that point in time. • It shall be possible with the PCC framework, in real-time, to monitor the overall amount of resources that are consumed by a user and to control usage independently from charging mechanisms, the so-called usage monitoring control. • The PCC framework shall support making policy decisions based on subscriber spending limits. • The PCC framework shall support making policy decisions for N6 traffic steering. The requirements of Session management related policy control include many different aspects, i.e. Gating control requirements, QoS control requirements at different levels (i.e. service data flow level, PDU session level, QoS flow level), Subscriber spending limits requirements (enforce policies based on subscriber spending limits based on information requested by PCF from CHarging Function, CHF), Usage monitoring control requirements (i.e. for PCF (Policy Control Function) to make / modify decisions of PCC rules), Application detection and control requirements. As mentioned in clause 4.3.6 of TS 23.503, Support for network capability exposure enables an AF (e.g. an external ASP) to request the following session management related policy control functionality from the NEF: Set or change a chargeable party at AF session setup (see clause 4.15.6.4 and 4.15.6.5 of TS 23.502 ); Set up an AF session with required QoS (see clause 6.1.3.22 and clause 4.15.6.6 of TS 23.502 ); Request QoS, traffic characteristics provisioning and performance monitoring for an individual UE or a group of UEs (see clause 4.15.6.14 of TS 23.502); Transfer of traffic characteristics of Time Sensitive Communication from the TSN AF (see clause 6.1.3.23) or from the TSCTSF (see clause 6.1.3.23a). Set up a time synchronization service from the TSCTSF (see clauses 5.27.1.8 and 6.1.3.23a ofTS 23.501 and clause 4.15.9 of TS 23.502). Based on the previous SA1 work and the SA2 ongoing topic, enhancements to Subscription and policy control should be introduced to support energy efficiency and energy saving as service criteria in Rel-19. However, based on the above reviews of the legacy techniques, for now, in the spec, there are not session or non-session related management policies and subscription considering the energy related aspects, i.e. energy credit / limit, energy consumption, requirements of energy saving, energy rate. In order to support the requirements in clause 5.2 of TR 23.700-66, enchantments to Subscription and policy control considering energy related aspects are desirable. According to a first aspect of the present invention, there is provided a method of an Application Function, AF, acquiring energy information from an Energy Information Function, EIF, in a telecommunication network, comprising the steps of: the AF issuing a subscription request to the EIF, via a Network Exposure Function, NEF; and the EIF responding, if authorised, with a confirmation; and the EIF further providing to the AF, via the NEF, energy information. In an embodiment, the NEF authorises the subscription request from the AF. In an embodiment, the energy information is energy consumption information. In an embodiment, the energy information is provided or requested at one of: User Equipment, UE, level; Protocol Data Unit, PDU, session level; and Quality of Service, QoS, flow level. In an embodiment, the AF further requests certain resources fora session. In an embodiment, if the request for the certain resources is approved, the PCF informs a Session Management Function, SMF, of the request and the SMF manages an associated session accordingly. In an embodiment, the request comprises an energy saving profile comprising at least one of a desired energy saving, consumption level, efficiency, communication service features that can be adjusted according to a required energy savings level and energy credit. In an embodiment, the subscription request also relates to an unsubscription request. According to a second aspect of the present invention, there is provided an apparatus arranged to perform the method of any preceding claim. In the context of embodiments of the present application, references to charging or charges relate primarily to monetary charges for an end user. The end user may be rewarded (or disadvantaged) in some way for conserving (or extravagantly using) energy. The reward may take the form of monetary discounts or increased / improved services in a later charging period. A disincentive may take the form of a reduced user experience. In essence, a user’s experience of the network may be affected by their energy usage, in positive or negative ways. For instance, a user who has used less energy than some form of defined target may be rewarded with an increased data allowance. According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows. Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims. For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which: Figures 1 to 4 show message flows according to embodiments of the invention. Embodiment of the invention aim to address the issues in Kl#2 by enhancing the session management related policy control with including energy related aspects. As required by SA1 in clause 6.15a.2.2 of TS 22.261, the 5GC shall define and enforce subscription and policies considering energy related aspects for services, e.g. by considering the maximum allowed energy consumption. Considering the significant cost on energy for 5GS operation, subject to operator policies, 3rd party service providers (referred to below as 3rd parties) and network operators may setup energy related limits or requirements for a service operation to limit the energy expense. For example, the AF and 5GC may apply the maximum energy consumption allowance / energy credit or minimum energy efficiency for delivering a service via 5GS to one or more users. In order to enforce the energy related requirements within 5GS, e.g. energy credit of a service, the AF and 5GC may apply different service operation quality requirements (e.g. different QoS) to different available energy consumption credits. Considering the above issues, the policy control with energy constraints should be agreed between the 3rd party and 5GC before the service starts. The agreed policy between 3rd party and 5GC can be used to monitor and manage the session(s) during the service operation to ensure that the 5GS provides the service in the required energy efficient way, e.g. by implementing the energy credit. During the service operation, the 5GS operation status might be varied by different reasons. As a result, the 5GS may be not able to satisfy the agreed energy related policy. In this case, the 5GC may take actions to enforce the energy policy (e.g. by modifying the AM or SM policies), or interact with the 3rd party to notify the new policies. In order to generate and enforce the policies with energy related requirements (e.g. energy credit or energy efficiency requirement) within 5GS and provide services in the energy-efficient way that can satisfy the demands of the 3rd party and network operators, interactions between the AF and 5GC are needed. Before the services starts, the AF may send the energy requirements and limits to the 5GC and require the 5GC to generate and authorise the policy for service operation. The AF may also optionally indicate some other service requirements along with the energy requirements, e.g. list of QoS parameters, potential service time windows, etc. Upon receiving the AF request, the 5GC (e.g. the PCF) will determine the energy related policy control. The policy decision will be made by considering multiple items of information, including the information in the AF request and the relevant information the PCF collects within 5GS. For example, the PCF can collect the prediction and statistics of energy consumption and efficiency from NWDAF and collect other energy related data from different data sources, e.g. OAM and the energy monitoring, management network function (EMF) if any, etc. The PCF will use the collected data to verify whether the energy requirements or limits in the AF request are implementable by 5GS or not. The 5GC may also consider the service quality requirements along with the energy information, if indicated by the AF. The determined policy will be notified by the PCF to the AF. The energy monitoring, management network function (EMF) can be a standalone network function or co-located with other network function (e.g. PCF, NWDAF, etc.). Note that the EMF may be known by one or more different terms and is not yet finalised in the relevant standards documents. One possible title is Energy Information Function (EIF). This may be implemented as a standalone NF or form a part of another NF such as PCF or NWDAF. Alternatively, the PCF may send a request to the monitoring and management network function (EMF) to collected data to verify whether the energy requirements or limits in the AF request are implementable by 5GS or not. Then the EMF sends the results back to the PCF. The EMF may also send PCF the possible QoS or the service quality can be provided, associated to different energy requirements or limits. The energy related measurement data (i.e. energy consumption of a PDU session, a QoS flow, UE(s), etc.) can be collected from OAM or energy monitoring and management network function (EMF), if any. The 5GC will also consider the service quality requirements along with the energy information, if indicated by the AF. The determined policy will be notified by the PCF to the AF. However, considering the 5GS performance and working principle, the energy related requirements in the AF request could be inapplicable for 5GS. In this case, the 5GS may not grant the AF request or may negotiate with the AF by providing alternative policies including the energy requirements or limits. For example, if the PCF verifies that energy consumption credit provided by the AF is not able to complete the required service, the PCF may not grant the AF request and notify AF about the result. Then the AF may send a new request to the 5GC. Or the 5GC may provide one or more alternative policies including applicable energy related requirements or limits / constraints and optionally the corresponding feasible service quality to the AF for negotiation. The AF will notify PCF the final decision on the energy policy for the service operation. During the service operation, in order to enforce the agreed energy related policy, the PCF may request or subscribe to data and notifications that are relevant to energy from multiple data sources, e.g. the PCF may subscribe to EMF (if any) to receive energy usage status related notification. Based on the reporting and notifications, the PCF will take actions to ensure that the agreed energy related policy can be satisfied. For example, the PCF can require energy consumption and energy efficiency related notification from OAM, or the appropriate 5GC NFs (i.e. SMF, EMF if any). If the energy consumption (e.g. of one or more PDU sessions, QoS flows, UEs) reaches a certain level, the PCF may lower the service quality requirements, e.g. by increasing the packet error rate to reduce retransmission and therefore to reduce the energy consumption, reducing the traffic volume for XR services, etc. Or if the PCF is notified that the energy consumption credit is used up, the PCF may determine to revoke the resources allocated to the service and terminate the service, or deactivate / suspend the session for a while until new energy consumption credit is available for service transmission. During the service operation, the PCF or AF may trigger policy modification in different scenarios, e.g. the energy consumption credit is changed from the AF side or the 5GS performance variation, the 5GC is not able to provide the service by enforcing in the agreed energy policy, etc. In this case, the PCF can generate new policies, subject to operator’s policy and based on data collected within 5GS and AF as described above. Then the PCF will inform the AF of the new policy. Further negotiation between the 5GC and AF on the acceptable policies is also possible. This solution provides an approach for the AF and 5GC to determine, modify and enforce the policy control considering energy constraints / requirements and limits. The AF and 5GC may negotiate the service operation strategies (e.g. QoS parameters) considering the required energy efficiency and allowed energy consumption credit. The 5GC can take actions to enforce the policy to limit the energy consumption or enhance the energy efficiency of a service. In this way, services can be provided to the subscribers in an energy efficient manner that satisfies the requirements of both the 3rd party and MNO. In embodiments of the invention: • energy includes any types of energy, i.e. renewable energy and non-renewable energy (including coal, oil and gas), if there is no other explicit explanation. • Renewable energy includes any types of sources that can be constantly being replenished, i.e. sunlight, wind etc. • Different granularities / levels include at RAN level, Core Network level, network slice level, UE level, PDU session level, and / or QoS flow level, if there is no other explicit explanation. The policy control framework of energy saving and energy efficiency is as required by SA1 in clause 6.15a.2.1 in TS 22.261: ‘For best-effort traffic, that is, without QoS criteria, policies can be defined to limit energy use for services. This is not In conflict with the principle that performance policies will not be traded off for energy efficiency, since best-effort service has no performance guarantees. Specifically, best-effort traffic can be subject to a policy that limits the maximum energy consumption over time, or further constrained by location (so that the energy consumption limit only applies when used in a specified service area.) Additionally, policies can be defined with a maximum energy credit limit, e.g. for besteffort services to limit the total amount of energy consumption according to an energy charging rate. These policies expand the options of subscription policies to control energy consumption in the 5G system.” In an embodiment, the Policy control framework of energy saving and energy efficiency is fully specified with introducing energy related aspects as the limits / constraint for a session / service etc. In the current specifications, there are no policy control mechanisms, and subscription information considers energy related aspects as part of the requirements / thresholds / constraints / conditions. For example, in the current session management related policy control frameworks, the AF session may consider charging related issues, QoS requirements, or request Qos, traffic characteristics provisioning and performance monitoring for UE(s), etc., are specified. Therefore, the 5GS transfer and manage the traffic in a more efficient manner, i.e. the 5GC may interact and negotiate with AF regarding the policy of transferring the service, generating the policy for resource utilization monitoring, etc. The procedures, as performed by the PCF can be replaced by any other 5GC NF, e.g. an energy monitoring and management related network function (EMF). Figure 1 shows the message exchanges involved in setting up an AF session with energy-related limits / requirements. The messages in this figure are labelled 1-13 and are described in detail below: 1. The AF sends a request to 5GC to request the policy control considering energy aspects for an AF session of one or multiples UEs using the Nnef_AFsessionWithEnergyLimit_Create request message. The AF may invoke the NEF service operation by using the Nnef_AFsessionWithEnergyLimit_Create request message. The request message to the NEF may include energy related requirements or allowance of a service. For example, the maximum energy consumption credit, the required energy efficiency of service operation, different energy consumption thresholds associated to different operation strategies, etc. Optionally, the AF may also indicate the requirements of the service quality corresponding energy requirements, for example, the minimum QoS requirements of the service associated to the required energy efficiency or the maximum energy consumption credit. The UE address(es), AF Identifier, DNN, S-NSSAI may also included in the request message. The AF sends a request to 5GC NF to indicate energy related limits / requirements for an AF session for one or multiples UEs using Nnef_AFsessionWithEnergyLimit_Create request message to the NEF. Nnef_AFsessionWithEnergyLimit_Create request may include: energy related requirements / limits and general information: energy related requirements / limits may include: o Energy related requirements / limits / maximum credit of energy consumption / energy usage / energy efficiency etc. o Energy related requirements / limits may be for a UE, group of UEs, a service (including multiple UEs); o Energy related requirements / limits might be at granularities / levels, i.e. at RAN level, Core Network level, network slice level, UE level, PDU session level, and / or QoS flow level. o The Energy related requirements / limits might be for a period of time, i.e., energy consumption during a period of time, i.e. an hour, a day, a month, etc.; Energy related requirements / limits of an area, i.e. energy consumption or energy efficiency of a cell, a list of cell(s) / TA(s) / beams / RAN notification area, energy efficiency area, etc. General information may include: address of a specific UE or multiple UEs to indicate the UEs to be involved into the service / AF session with energy related requirements / limits, AF Identifier to identify the AF, S-NSSAI (i.e. if the energy related limits / constraints are for slice granularity), DNN etc. The AF may indicate the Qos requirements, Qos parameters, alternative Qos requirement of the service with energy limit / requirement to 5GC (i.e. PCF or the energy monitoring and management related NF, via NEF ifthe AF not trusted), if any 2. The NEF authorizes the AF request that contains Energy related requirements / limits and may apply policies to control the overall amount of energy consumption / energy usage authorized for the AF. Ifthe authorisation is not granted, all steps (except step 5) are skipped and the NEF replies to the AF with a Result value indicating that the authorisation failed. The NEF may provide alternative recommended Energy related requirements / limits to the AF for further use / negotiation. 3. The NEF uses the UE address(es) indicated in step 1 to discover the PCF(s) from the BSF. Then the NEF forwards the parameters received in step 1 to the PCF by invoking PCF service operation, e.g. Npcf_ / Nemf_EnergyPolicyAuthorization_Create request message. Or the NEF discovers the management related network function (EMF). If the AF is considered to be trusted by the operator, the AF uses the Npcf_ / Nemf_EnergyPolicyAuthorization_Create message to interact directly with PCF / EMF to indicate and negotiate the energy related limits for an AF session, without via the NEF. 4. The PCF / EMF determines whether to authorise the request from the NEF in step 3. In order to determine whether the request could be authorised or not, the PCF may collect energy information from multiple data sources, e.g. NWDAF, OAM, SMF, energy monitoring and management network function (EMF) if any, etc. For example, the PCF may trigger the NWDAF to provide the prediction and statistics of energy consumption or energy efficiency at different granularities, the PCF may collect energy related measurements from EMF, OAM or other 5GC NF to understand the energy consumption over a period of time, etc. Based on the collected information, the PCF is able to verify whether the AF request can be satisfied by the 5GS or not. If the PCF / EMF determines that the AF request is not able to be satisfied by the 5GS, the 5GC may reject the AF request and notify the outcome to the AF. The PCF may determine to negotiate with AF regarding the policy, i.e. by providing alternative policies including the energy related requirements or limit that can be provided by 5GS to the AF. For example, the PCF may generate different implementable energy consumption allowance and energy efficiency along with different service operation strategies. For requests received from the NEF in step 3, the PCF / EMF determines whether the request is authorized and notifies the NEF if the request is not authorized. If the request is authorized, the PCF / EMF derives / collects energy related information based on the information provided by the NEF in step 3 or directly provided by the AF. The PCF will determine and check whether the energy related limits / requirements can be satisfied / achieved by the 5GS or not. The PCF / EMF will generate the policies related to energy control and will notify the result to the NEF. If the AF is considered to be trusted by the operator, the PCF / EMF will notify the results to the AF directly, via Npcf_ / Nemf_EnergyPolicyAuthorization_Create response message. The PCF may determine and authorise the energy related requirements / policy control based on the parameters provided by NEF / AF, and also the multiple data collected / requested / subscribed to from other 5GC NFs, OAM, RAN node, UEs, etc. o In order to collect / request data from other entities and subscribe to other entities for notification of the data of interests, the PCF / EMF may trigger some procedures towards other 5GC NFs, OAM, RAN node, UEs to collect / monitor / derive information related to energy, i.e. PCF triggers NWDAF to derive and notify PCF / EMF of the prediction and statistics of energy consumption / energy efficiency / energy requirements based on parameters indicated by the PCF, or the PCF may collect energy related information from the energy monitoring / management NF, PCF triggers Qos monitoring or other measurements towards SMF, UPF etc. o The procedures / events triggered by the PCF / EMF to collected data related (directly or indirectly) to energy information can be considered as part of the energy related policy control. The energy control related policies might include multiple parameters / requirements, i.e. generated by the PCF / EMF. The policies may include: the maximum allowed (overall) energy credit (i.e. for a service, a UE, multiple UEs, one or multiple RAN node, Core Network, network slice, UE, PDU session level, and / or QoS flow level etc.). Optionally, the PCF may also notify the QoS parameters / requirements / 5QI of the service / service flow / QoS flow / AF session along with the energy related requirements. If more than one service requirements / parameters are provided, i.e. more than maximum energy credit, max. energy consumption allowance, maximum / minimum energy efficiency, maximum / minimum energy rate, energy states of 5GC / NF / RAN node / UE / PDU session / Qos flow are provided, the PCF / EMF may derive the possibility / probability / likelihood / priority of the energy related requirements / limits. o Optionally, the PCF / EMF provide the service requirements / parameters could be provided by 5GC (i.e. QoS parameters / requirements / 5QI, latency, data rate / throughput etc.) along with the corresponding energy related limits / requirements. Therefore, the AF / NEF would understand the service quality can be provided by 5GS of the corresponding energy related aspects (i.e. energy consumption, energy efficiency, require max. energy credit). o The PCF / NEF / AF / EMF may prioritise the service requirements / parameters with higher possibility / probability / likelihood / priority to provide the service to the users, considering the policy requirements, (service / operator) configuration. o The PCF / NEF / AF / EMF may prioritise the requirements / parameters with the lowest energy consumption, highest efficiency etc. as higher priority, i.e. considering the energy cost / price. o The PCF / EMF may also generate energy related rules / policies to trigger procedures / events toward other 5GC NF / RAN / UE etc. i.e. resource monitoring, parameters... The PCF I EMF may determine to update the energy related policy, i.e. based on the request from AF / NEF, based on monitoring results reported to PCF / event notification from other 5GC NF / RAN / UE / OAM, etc. i.e. the PCF may determine to update the energy related policy based on notification / request from the energy monitoring and management related NF, SMF, UPF when energy related events are triggered. The energy related events could be triggered based on energy consumption, energy usage reach a threshold / limit, based on efficiency (i.e. the efficiency is lower or higher than a threshold / limit). The PCF / EMF may update / modify the determined policy and inform the policy to the consumers, i.e. other 5GC NF / RAN / UE / NEF, the 5GC may also notify the new policy to AF (via NEF). Based on the event triggered / notification / the monitoring results, the PCF may also determine to revoke the policy and resources / configuration allocated corresponding to this policy, or determine to terminate / revoke the service and notify the AF, NEF, 5GC NFs (i.e. SMF, UPF, etc.), RAN, UE, etc. The PCF / EMF may notify the update / modification / revoke / delete of the policies to AF, NEF, 5GC NFs (i.e. SMF, UPF, etc.) by invoking the corresponding pcf_update / modification / revoke / delete service operations. 5. The PCF / EMF notifies the NEF about whether the request in step 3 authorised or not by sending Npcf_ / Nemf_PolicyAuthorization_Create response message. As mentioned in step 4, the PCF may also include the alternative policies including the energy related requirements or limit that can be provided by 5GS to the AF for energy policy negotiation. The NEF sends a Nnef_AFsessionWithEnergyLimit_Create response (Transaction Reference ID, Result) to the AF. Result indicates whether the request is granted or not. The NEF may also include the accepted / proposed / determined energy related information / parameters in the response message, i.e. the max. energy credit / energy consumption / energy usage allowance / energy efficiency at one or more different granularities / of a UE or multiple Ues / of a service, etc. Upon receiving the response message, the AF acknowledges that whether the request towards 5GC with energy related requirements is accepted or not, and the accepted energy related requirements by 5GC, and the priority / likelihood / probability of the accepted energy related requirements (if more than one accepted energy related requirements are indicated). 6. The NEF sends a Nnef_AFsessionWithEnergyLimit_Create response (Transaction Reference ID, Result, optionally alternative policy) to the AF to indicate the authorisation outcome. 7. Conditionally, if the PCF / EMF determines to negotiate with AF and sends more than one alternative policies to the AF in step 5 and 6, to align the understanding between AF and 5GC about the policy to be applied, the AF needs to choose and inform the 5GC about the acceptable policy by invoking Nnef_AFsessionWithEnergyLimit_Update request. 8. - 10. Conditionally, the NEF forwards the selected policy from AF to PCF / EMF. The PCF I EMF acknowledges NEF. NEF responds to the AF request about the policy acceptance by PCF / EMF. 11.- 13. After the agreement of energy related policy is successfully established between AF and 5GC, the NEF may subscribe to events or notifications of energy usage or energy efficiency of PDU session, QoS flow, UE(s) etc., and other events (e.g. QoS monitoring, data volume during a period of time, session activation and inactivation time etc.) during the service operation. When the condition is met, i.e. when the energy consumption reaches a certain level, or the energy efficiency is lower than a threshold, the PCF / EMF may notify the NEF about the events and the values of the energy related parameters. The NEF sends notify message with the events and parameters reported by the PCF I EMF to the AF. After the session / resources / agreements are successfully make between AF and 5GC / 5GC NF / PCF / energy monitoring and management related NF, the NEF may subscribe to events / notifications of energy related policy modification / updates, energy related monitoring results / alters / warning, resource allocation status based on energy usage / energy consumption / energy efficiency, the energy status of 5GC / 5GC NF / RAN / UE etc. (if available), etc. When the event condition related to energy is met by the PCF / EMF, e.g. that the energy consumption is higher than a threshold, the energy efficiency is lower than a threshold, the max. energy credit is used up / met, the data volume / throughput is higher than a threshold, the 5GC cannot provide the service with required energy limits / parameters etc., the PCF / EMF sends Npcf_ / Nemf_EnergyPolicyAuthorization_Notify message to the NEF notifying about the energy related events. If the AF is considered to be trusted by the operator, the PCF / EMF sends the Npcf_ / Nemf_EnergyPolicyAuthorization_Notify message directly to AF. The NEF sends Nnef_AFsessionWithEnergyLimit_Notify message with the event reported by the PCF to the AF in step 7 The AF may send request to NEF in order to revoke the AF request with energy related requirements. The NEF authorizes the revoke request and triggers the PCF / EMF service to PCF / EMF to revoke / delete the AF request, i.e. Npcf_ / Nemf_EnergyPolicyAuthorizationEnergy_Delete service operations for the AF request. If the AF is trusted by the operator, the AF directly sends the request to the PCF / EMF to revoke / delete the previous AF request. The PCF / EMF or AF can modify or update the previously agreed energy related policy in different scenarios, i.e. energy consumption credit is changed from the AF side, since the 5GC might not be able to provide the service in the agreed manner considering the energy limits, or the operator’s policy can changed, etc. The PCF can generate new policies subject to operator’s policy and based on data collected within 5GS (i.e. from NWDAF, energy monitoring and management NF, OAM, RAN node, etc.) and AF requirements if any. Then the PCF / EMF will inform the AF of the new policy. Further negotiation between the 5GC and AF on the acceptable policies is also possible. Figure 2 shows the messages exchanged in a further embodiment setting up an AF session with energy related limits / requirements. The messages in this figure are labelled 1-8 and are described in detail below: 1. The AF sends a request to 5GC NF to indicate energy related limits / requirements for an AF session for one or multiples UEs using Nnef_AFsessionWithEnergyLimit_Create request message to the NEF. Nnef_AFsessionWithEnergyLimit_Create request may include: energy related requirements / limits and general information: energy related requirements / limits may include: o Energy related requirements / limits / maximum credit of energy consumption / energy usage / energy efficiency etc. o Energy related requirements / limits may be for a UE, group of UEs, a service (including multiple UEs); o Energy related requirements / limits might be at granularities / levels, i.e. at RAN level, Core Network level, network slice level, UE level, PDU session level, and / or QoS flow level. o The Energy related requirements / limits might be for a period of time, i.e., energy consumption during a period of time, i.e. an hour, a day, a month, etc.; Energy related requirements / limits of an area, i.e. energy consumption or energy efficiency of a cell, a list of cell(s) / TA(s) / beams / RAN notification area, energy efficiency area, etc. General information may include: address of a specific UE or multiple UEs to indicate the UEs to be involved into the service / AF session with energy related requirements / limits, AF Identifier to identify the AF, S-NSSAI (i.e. if the energy related limits / constraints are for slice granularity), DNN etc. The AF may indicate the Qos requirements, Qos parameters, alternative Qos requirement of the service with energy limit / requirement to 5GC (i.e. PCF or the energy monitoring and management related NF, via NEF ifthe AF not trusted), if any 2. The NEF authorizes the AF request that contains Energy related requirements / limits and may apply policies to control the overall amount of energy consumption / energy usage authorized for the AF. If the authorisation is not granted, all steps (except step 5) are skipped and the NEF replies to the AF with a Result value indicating that the authorisation failed. The NEF may provide alternative recommended Energy related requirements / limits to the AF for further use / negotiation. 3. The NEF uses the UE address(es) indicated in step 1 to discover the PCF(s) from the BSF. The NEF forwards received parameters indicated in step 1 to the PCF in the Npcf_ / Nemf_EnergyPolicyAuthorization_Create request message. Or the NEF discovers the management related network function (EMF). If the AF is considered to be trusted by the operator, the AF uses the Npcf_ / Nemf_EnergyPolicyAuthorization_Create message to interact directly with PCF / EMF to indicate and negotiate the energy related limits for an AF session, without via the NEF. 4. For requests received from the NEF in step 3, the PCF / EMF determines whether the request is authorized and notifies the NEF if the request is not authorized. If the request is authorized, the PCF / EMF derives / collects energy related information based on the information provided by the NEF in step 3 or directly provided by the AF. The PCF / EMF will determine and check whether the energy related limits / requirements can be satisfied / achieved by the 5GS or not. The PCF / EMF will generate the policies related to energy control and will notify the result to the NEF. If the AF is considered to be trusted by the operator, the PCF I EMF will notify the results to the AF directly, via Npcf_ / Nemf_EnergyPolicyAuthorization_Create response message. The PCF / EMF may determine and authorise the energy related requirements / policy control based on the parameters provided by NEF / AF, and also the multiple data collected / requested / subscribed to from other 5GC NFs, OAM, RAN node, UEs, etc. o In order to collect / request data from other entities and subscribe to other entities for notification of the data of interests, the PCF / EMF may trigger some procedures towards other 5GC NFs, OAM, RAN node, UEs to collect / monitor / derive information related to energy, i.e. PCF / EMF triggers NWDAF to derive and notify PCF / EMF of the prediction and statistics of energy consumption / energy efficiency / energy requirements based on parameters indicated by the PCF / EMF, or the PCF / EMF may collect energy related information from the energy monitoring / management NF, PCF triggers Qos monitoring or other measurements towards SMF, UPF etc. o The procedures / events triggered by the PCF / EMF to collected data related (directly or indirectly) to energy information can be considered as part of the energy related policy control. The energy control related policies might include multiple parameters / requirements, i.e. generated by the PCF / EMF. The policies may include: the maximum allowed (overall) energy credit (i.e. for a service, a UE, multiple UEs, one or multiple RAN node, Core Network, network slice, UE, PDU session level, and / or QoS flow level etc.). Optionally, the PCF may also notify the QoS parameters / requirements / 5QI of the service / service flow / QoS flow / AF session along with the energy related requirements. If more than one service requirements / parameters are provided, i.e. more than maximum energy credit, max. energy consumption allowance, maximum / minimum energy efficiency, maximum / minimum energy rate, energy states of 5GC / NF / RAN node / UE / PDU session / Qos flow are provided, the PCF may derive the possibility / probability / likelihood / priority of the energy related requirements / limits. o Optionally, the PCF / EMF provide the service requirements / parameters could be provided by 5GC (i.e. QoS parameters / requirements / 5QI, latency, data rate / throughput etc.) along with the corresponding energy related limits / requirements. Therefore, the AF / NEF would understand the service quality can be provided by 5GS of the corresponding energy related aspects (i.e. energy consumption, energy efficiency, require max. energy credit). o The PCF / NEF / AF / EMF may prioritise the service requirements / parameters with higher possibility / probability / likelihood / priority to provide the service to the users, considering the policy requirements, (service / operator) configuration. o The PCF / NEF / AF I EMF may prioritise the requirements / parameters with the lowest energy consumption, highest efficiency etc. as higher priority, i.e. considering the energy cost / price. o The PCF I EMF may also generate energy related rules / policies to trigger procedures / events toward other 5GC NF / RAN / UE etc. i.e. resource monitoring, parameters... The PCF I EMF may determine to update the energy related policy, i.e. based on the request from AF / NEF, based on monitoring results reported to PCF / event notification from other 5GC NF / RAN / UE / OAM, etc. i.e. the PCF may determine to update the energy related policy based on notification / request from the energy monitoring and management related NF, SMF, UPF when energy related events are triggered. The energy related events could be triggered based on energy consumption, energy usage reach a threshold / limit, based on efficiency (i.e. the efficiency is lower or higher than a threshold / limit). The PCF I EMF may update / modify the determined policy and inform the policy to the consumers, i.e. other 5GC NF / RAN / UE / NEF, the 5GC may also notify the new policy to AF (via NEF). Based on the event triggered / notification / the monitoring results, the PCF / EMF may also determine to revoke the policy and resources / configuration allocated corresponding to this policy, or determine to terminate / revoke the service and notify the AF, NEF, 5GC NFs (i.e. SMF, UPF, etc.), RAN, UE, etc. The PCF / EMF may notify the update / modification / revoke / delete of the policies to AF, NEF, 5GC NFs (i.e. SMF, UPF, etc.) by invoking the corresponding pcf_update / modification / revoke / delete service operations. 5. The NEF sends a Nnef_AFsessionWithEnergyLimit_Create response (Transaction Reference ID, Result) to the AF. Result indicates whether the request is granted or not. The NEF may also include the accepted / proposed / determined energy related information / parameters in the response message, i.e. the max. energy credit / energy consumption / energy usage allowance / energy efficiency at one or more different granularities / of a UE or multiple Ues / of a service, etc. Upon receiving the response message, the AF acknowledges that whether the request towards 5GC with energy related requirements is accepted or not, and the accepted energy related requirements by 5GC, and the priority / likelihood / probability of the accepted energy related requirements (if more than one accepted energy related requirements are indicated). 6. After the session / resources / agreements are successfully make between AF and 5GC / 5GC NF / PCF / energy monitoring and management related NF, the NEF may subscribe to events / notifications of energy related policy modification / updates, energy related monitoring results / alters / warning, resource allocation status based on energy usage / energy consumption / energy efficiency, the energy status of 5GC / 5GC NF / RAN / UE etc. (if available), etc. 7. When the event condition related to energy is met by the PCF / EMF, e.g. that the energy consumption is higher than a threshold, the energy efficiency is lower than a threshold, the max. energy credit is used up / met, the data volume / throughput is higher than a threshold, the 5GC cannot provide the service with required energy limits / parameters etc., the PCF / EMF sends Npcf_ / Nemf_EnergyPolicyAuthorization_Notify message to the NEF notifying about the energy related events. If the AF is considered to be trusted by the operator, the PCF / EMF sends the Npcf_ / Nemf_EnergyPolicyAuthorization_Notify message directly to AF. 8. The NEF sends Nnef_AFsessionWithEnergyLimit_Notify message with the event reported by the PCF to the AF in step 7 Figure 3 illustrates an embodiment including setting up an AF session with energy related limits and requirements. The messages in this figure are labelled 1-14 and are described in detail below: 1. The AF sends a request to 5GC to request the policy control considering energy aspects for an AF session of one or multiples UEs. The AF may invoke the NEF service operation by using the Nnef_AFsessionWithEnergyLimit_Create request message. The request message to the NEF may include energy related requirements or allowance of a service, e.g. the max. energy consumption credit, the required energy efficiency of service operation, different energy consumption thresholds associated to different operation strategies (e.g. QoS), etc. The UE address(es), AF Identifier, DNN, S-NSSAI may also included in the request message. Optionally, the AF may also indicate the requirements of the service quality corresponding energy requirements, for example, the minimum QoS requirements of the service associated to the required energy efficiency or the maximum energy consumption credit. 2. The NEF authorizes the AF request that contains energy related requirements for the AF session. If the authorisation is not granted by NEF, the following steps (except for step 6) will be skipped and the NEF indicates to the AF about the authorisation failure. 3. The NEF uses the UE address(es) indicated in step 1 to discover the PCF(s) from the BSF. Then the NEF forwards the parameters received in step 1 to the PCF to authorise and generated energy related policy, e.g. by invoking PCF service operation Npcf_EnergyPolicyAuthorization_Create request message. If the AF is considered to be trusted by the operator, the AF invokes the PCF service operation (e.g. Npcf_EnergyPolicyAuthorization_Create) directly to the PCF to indicate and negotiate the energy related requirement or limits for the AF session. 4. The PCF determines whether to authorise the request from the NEF in step 3. 4a In order to determine whether the request could be authorised or not, the PCF may collect energy information from multiple data sources, e.g. NWDAF, OAM, SMF, EMF if any, etc. For example, the PCF may trigger the NWDAF to provide the prediction and statistics of energy consumption or energy efficiency at different granularities, the PCF may collect energy related measurements from EMF, OAM or other 5GC NF, etc. 4b PCF determines whether to authorise the AF request or not and determine energy policy. Based on the collected information, the PCF is able to evaluate whether the request from AF can be satisfied by the 5GS or not. If the PCF determines that the AF request is not able to be satisfied by the 5GS, the 5GC may reject the AF request and notify the outcome to the AF. The PCF may determine to negotiate with AF regarding the policy, i.e. by providing alternative policies including the energy related requirements or limit that can be provided by 5GS to the AF. For example, the PCF may generate different implementable energy consumption allowance / credit and energy efficiency , optionally associated with different service operation strategies. 5. The PCF notifies the NEF about whether the request in step 3 authorised or not by sending Npcf_PolicyAuthorization_Create response message. As mentioned in step 4, the PCF may also include the alternative policies including the energy related requirements or limit that can be provided by 5GS to the AF for energy policy negotiation. 6. The NEF sends a Nnef_AFsessionWithEnergyLimit_Create response (Transaction Reference ID, Result, optionally alternative policy) to the AF to indicate the authorisation outcome. 7. [CONDITIONAL] if the PCF determines to negotiate with AF and sends more than one alternative policies to the AF in step 5 and 6, to align the understanding between AF and 5GC about the energy policy to be applied, the AF needs to choose and inform the 5GC about the accepted policy by invoking Nnef_AFsessionWithEnergyLimit_Update request. 8. - 10. [CONDITIONAL] the NEF forwards the selected policy from AF to PCF. The PCF acknowledges NEF. NEF responds to the AF request about the policy acceptance by PCF. 11. After the agreement of energy related policy is successfully established between AF and 5GC, the NEF may subscribe to events or notifications of energy usage or energy efficiency of PDU session, QoS flow, UE(s) etc., and other events (e.g. QoS monitoring, data volume during a period of time, session activation and inactivation time etc.) during the service operation. 12. The PCF may subscribe to different data sources for the energy related information exposure or notification to assist PCF with energy related policy update. 12a PCF may subscribe to EMF (if any) for the energy related information exposure or notification, for example for the energy usage status related notification, e.g. energy usage reaches a threshold or the energy credit is used up, or energy efficiency is lower than a threshold, etc. 12b the PCF may subscribe to NWDAF for the energy related analytics, to OAM for energy related measurements at NF / slice / gNB level, to SMF for the data rate and traffic volume, etc. 13. When the condition is met, the PCF notifies the NEF about the events and optional the values of the energy related parameters. 14. The NEF sends notify message with the events and parameters reported by the PCF to the AF. The PCF or AF can modify or update the previously agreed energy related policy in different scenarios since the 5GC might not be able to provide the service in the agreed manner considering the energy limits or operator’s policy, i.e. in the scenarios that energy consumption credit is changed from the AF side or 5GS performance degradation, etc. The PCF can generate new policies or update existing policies subject to operator’s policy and based on data collected within 5GS (i.e. from NWDAF, energy monitoring and management NF, OAM, RAN node, etc.) and AF. Then the PCF will inform the AF of the new policy. Further negotiation between the 5GC and AF on the acceptable policies is also possible. Figure 4 shows an embodiment including setting up an AF session with required Energy savings procedure. The messages in this figure are labelled 1-14 and are described in detail below: 1. The AF sends a request to reserve resources for an AF session with energy savings criteria using Nnef_AFsessionWithQoS_Create request message including QoS parameters and energy saving profile information which may include energy savings level, the energy credit, required energy efficiency and optionally features subject to energy savings control / adjustment. 2. The NEF checks authorization for the AF request and may apply policies to verify that that feature based energy savings control can be authorized for the AF and the features allowed to be under energy related requirement, e.g. savings control, the energy credit, required energy efficiency If the authorization is not granted, the NEF rejects the request otherwise proceeds with the following steps. 3. The NEF forwards received parameters to the PCF in the Npcf_PolicyAuthorization_Create request. 4. The PCF sends to the NWDAF or EECF a request to retrieve energy consumption analytics by providing Application Identifier, QoS parameters and the list of features subject to energy control / adjustment (e.g. which can be adjusted or enabled / disabled for the communication service). The PCF receives the energy consumption data from the NWDAF / EECF including per feature relative contribution to the energy consumption associated with the service / session. 5. The PCF determines a policy configuration for the PDU Session (i.e. PCC rules, etc.) using the energy consumption data and requested session energy related profile to achieve the desired energy requirements in the AF request (e.g. the energy saving level, the energy credit, required energy efficiency). The PCF determines the features for which PCC rules and other policy configuration information that needs to be established or updated for the adjustment / disablement of the features accordingly. 6. The PCF sends Npcf_PolicyAuthorization_Create response informing the NEF / AF whether the request is granted and includes information on the adjusted or de / activated features and energy policy and requirements for the session. If the NEF / AF request cannot be granted by the PCF (e.g. due to the available energy credit or required energy efficiency cannot be met), the PCF may determine to negotiate with AF on the application energy related criteria. 6 -6a.[Conditional] if the PCF determines to negotiate with AF, the PCF may include one or more alternative energy related criteria, optionally along with the policies, to the AF (via NEF). 6b-6c. [Conditional] The AF may choose the acceptable energy related criterion and inform the PCF of the decision (via NEF). If the AF cannot choose any acceptable energy related criterion provided by the PCF, based on its internal logic, the AF will also inform the PCF of this outcome. 7. The PCF updates the SMF with the corresponding policy indicating rules for the features adjustment or de / activation for energy related requirements, e.g. energy savings, energy credit, required energy efficiency etc.. The SMF applies the policy with energy savings rules to the PDU Session and notifies the PCF of success or failure. 8. The PCF notifies the NEF / AF the SMF when the establishment of the transmission resources with corresponding energy requirements succeeded or failed. In this embodiment, considering the 5GS performance might be varied due to different reasons, the energy related criteria or requirements in the AF request or the authorised energy related criteria might be not applicable. In this case, the 5GS may determine to negotiate with the AF by providing alternative policies and energy criteria. For example, if the PCF verifies that energy credit provided by the AF is not able to complete the required service at the desired level, the PCF may indicate the alternative energy credit(s) and the associated assistance information (e.g. QoS, data volume, etc.) to the AF (via NEF) for negotiation. The AF will notify PCF the final decision on the energy policy for the service operation. At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as 'component', ‘module’ or ‘unit’ used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of an Application Function, AF, acquiring energy information from an Energy Information Function, EIF, in a telecommunication network, comprising the steps of:the AF issuing a subscription request to the EIF, via a Network Exposure Function, NEF; andthe EIF responding, if authorised, with a confirmation; andthe EIF further providing to the AF, via the NEF, energy information.

2. The method of claim 1 wherein the NEF authorises the subscription request from the AF.

3. The method of any preceding claim wherein the energy information is energy consumption information.

4. The method of any preceding claim wherein the energy information is provided or requested at one of: User Equipment, UE, level; Protocol Data Unit, PDU, session level; and Quality of Service, QoS, flow level.

5. The method of any preceding claim wherein the AF further requests certain resources for a session.

6. The method of claim 5 wherein if the request for the certain resources is approved, the PCF informs a Session Management Function, SMF, of the request and the SMF manages an associated session accordingly.

7. The method of claim 5 or 6 wherein the request comprises an energy saving profile comprising at least one of a desired energy saving, consumption level, efficiency, communication service features that can be adjusted according to a required energy savings level and energy credit.

8. The method of any preceding claim wherein the subscription request also relates to an unsubscription request.

9. Apparatus arranged to perform the method of any preceding claim.31

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