Energy consumption-based handover and load balancing in mobile networks

Abstract

Described is a radio access network (RAN) entity (407, 501, 902) configured to operate as a source node during a communication session with a user equipment (UE), the RAN comprising other nodes (408, 409, 410, 903) capable of communicating with the UE, the RAN entity being configured to: report (1401) energy consumption and / or load information for the RAN entity to a core network control plane entity; send (1402) a request to the core network control plane entity for handover of the UE from the source node to a target node; receive (1403) an indication of a target node to which the UE in communication with the RAN entity is to be handed over to; and initiate (1404) handover to transfer the UE to the target node. A mechanism at the core network control plane and an approach for reducing energy consumption by load balancing is also described. This may allow energy consumption to be reduced in a mobile network.

Description

[0001] ENERGY CONSUMPTION-BASED HANDOVER AND LOAD BALANCING IN MOBILE NETWORKS

[0002] FIELD OF THE INVENTION

[0003] This invention relates to reducing energy consumption in mobile networks, particularly during handover through selecting energy efficient target nodes and through dynamic load balancing procedures based on energy consumption monitoring.

[0004] BACKGROUND

[0005] Global temperature is rising due to climate change and increased carbon emissions. Reducing the carbon footprint to ensure environmental sustainability is hence a major global issue. Every nation and organizations are encouraged to take corrective measures to combat the issue of climate change. Organizations are encouraged to focus on sustainability in every aspect of their product and service lifecycle.

[0006] Mobile networks are considered an essential part of the increasingly digital society. They have become crucial in today’s economy, as many businesses rely upon them for their operation. However, due to the increasing modernization of the society, and mobility, the number of mobile network users has grown unprecedentedly. This has resulted in an exponential increase in the mobile network’s energy consumption and their corresponding carbon- footprint. According to the Global System for Mobile Communications Association, 25% of mobile network operators’ costs are due to OPEX and 90% of this costs are due to energy consumption (EC). Moreover, most of this energy expenditure comes from the Radio Access Networks (RAN) while Core Network (CN) and physical transport account for a smaller share. On the other hand, every entity in a mobile network experiences heterogeneous loads and as a result exhibits different EC characteristics at different times.

[0007] In most network, at any given time, there are some congested links and some underutilized links. Traffic steering is usually employed in todays’ networks to redistribute the packets in a flow to achieve a more uniform distribution of the traffic on all available links. There are many different types of steering mechanisms in a Traffic Engineering solution, usually based on the characteristics used for traffic distribution, such as link quality, load balance and bandwidth capacity. State-of-the-art Quality of Service (QoS) and Policy frameworks also utilize Traffic Engineering to improve the latency and reliability of the network. Overall, application of Traffic Engineering has been seen to improve the resource efficiency of the networks and the Quality of Experience (QoE) of end users. In the 3rdGeneration Partnership Project (3GPP), traffic steering is applied for the uplink traffic in the Core Network to direct traffic to a pre-configured data network access identifier (DNAI), while traffic steering in access traffic steering, switching and splitting (ATSSS) splits the traffic between 3GPP and non-3GPP networks.

[0008] During mobility, a user equipment (UE) moves from one cell to another, where a cell represents the coverage area offered by a Base Station (BS). When a UE moves from one cell to another, when a BS wants to perform load balancing, or when the signal conditions experienced by a UE are below an expected threshold, traditionally, a handover is performed to ensure session continuity and maintain high QoS for users.

[0009] During handover, a Source BS (SBS) to which the UE is currently connected with selects a Target BS (TBS) and a series of signaling messages are exchanged between the SBS and the TBS and their respective Core Network Control Planes with the goal of reassigning a user’s resources present in the SBS in the TBS. There are three different types of handovers. Firstly, Intra BS Handover, where the UE moves between cells but it is still connected to the same BS, i.e., the BS handovers the UE to a different signal in the spectrum offered by the same BS. Secondly, Inter-BS Handover, where the handover is performed from an SBS to a TBS. Thirdly, Inter-RAT Handover, where the handover is performed between an SBS and TBS of different technologies (for example, the SBS is a gNodeB (gNB) while the IBS is an eNodeB (eNB)). During Inter-BS and Inter-RAT handovers, the core networks are also involved during the handover.

[0010] 3GPP Releases 18 and 19 have focused efforts towards studying the aspects related to achieving energy efficiency in mobile networks. As part of the ongoing efforts, the Key Performance Indicators (KPIs) such as bandwidth, latency, data volume and metrics to measure the EC of mobile networks have been developed in SA5. The 3GPP TS 28.550 provides mechanisms in Management Plane (MP) to request EC information of the network through creating monitoring events in the respective network entities.

[0011] Essentially, a MP (management plane) network function (MnF) sends HTTP requests to the selected network entities for creating monitoring events in them. The resulting EC information in the network entities is sent back as response to the MnF. Further, TS 28.553 provides capabilities to expose the information available in MP to interested parties, including externals through subscriptions to corresponding management services.

[0012] With regards to Control Plane (CP), the 3GPP Release 19 TR 23700-66 identifies three different energy related key issues and studies the following energy related aspects for the key issue on “Network energy related information exposure”: 1) whether and what network energy related information can be exposed, 2) at what granularity (for example, per network slice, User Equipment (UE), Network Function (NF), Protocol Data Unit (PDU) Session, Quality of Service (QoS) flow, etc.) the network energy related information can be exposed, 3) how the network energy related information is exposed and 4) how and what network energy related information from the network entities (i.e. RAN nodes, 5GC NFs) can be obtained in order to support network energy related information exposure. There are various solutions proposed to address the above-mentioned key issues where new NFs (for example, energy efficiency control function (EECF)) are proposed that collect energy related information or information that has impact on EC and / or energy efficiency (EE) and derive an estimation of consumed energy from the collected energy-related information.

[0013] The current state-of-the-art on the subject of energy consumption mainly focus on using energy related information from RAN and Core NFs (such as data volume) to derive energy consumption estimations and expose them to interested third parties. Reporting the EC of a network at various granularities is a very important factor in reducing the overall energy consumption of the End-to-End (E2E) session. However, in all of the above-mentioned prior art, traffic steering and load balancing do not consider the energy related state of the participating nodes. Moreover, the traffic steering information is only configured in the Core Network and specifically for directing the traffic to a certain DNAI, without regards to the EC of the RAN nodes and the load experienced by them. Additionally, state-of-the-art handover procedures in RAN are mainly based on only radio conditions for selecting a Target Base Station during a handover [TS 28.104],

[0014] Figure 1 shows the state-of-the-art handover performed during mobility in a mobile network 100. The network comprises base stations 101 and 102 each in communication with a UE, 103 and 104 respectively. The network also comprises a Core control plane (CP) 105, user plane function (UPF) 106 and a data network (DN) 107. When UE 103 moves away from SBS 101 towards TBS 102, handover of the UE103 from BS 101 to BS 102 may be initiated. However, the SBS 101 does not know the energy state of the TBS 102.

[0015] Figure 2 highlights a problem with load and as a consequence the increased EC of the target entities in a mobile network 200. The network comprises base stations 201 and 202 each in communication with multiple UEs, shown generally at 203 and 204 respectively. The network also comprises a Core CP 205, UPF 206 and a DN 207. Some of the entities, such as BS 202 and UPF 206, may be overloaded and hence have a high EC. Traditional ways of performing handovers for load balancing in RANs can also lead to ping-pong effect, handover interruptions, and increased EC when UEs are handed over. In summary, the network does not leverage information on network traffic load and energy state of entities to perform dynamic load balancing and handovers.

[0016] It is desirable to develop an approach that may overcome at least some of the above issues.

[0017] SUMMARY OF THE INVENTION

[0018] According to a first aspect, there is provided a radio access network entity configured to operate as a source node in a radio access network of a mobile network during a communication session with a user equipment, the radio access network comprising one or more other nodes capable of communicating with the user equipment, the radio access network entity being configured to: report energy consumption information and / or load information for the radio access network entity to a core network control plane entity of the mobile network; send a request to the core network control plane entity for handover of the user equipment from the source node to a target node of the one or more other nodes of the radio access network; receive, from the core network control plane entity, an indication of a target node to which the user equipment in the communication session with the radio access network entity is to be handed over to; and initiate a handover procedure to transfer the user equipment to the target node.

[0019] This may provide a mechanism at RAN nodes via which energy consumption can be reduced with energy-efficient handover procedures.

[0020] The request for handover of the user equipment may comprise a request for an energy-efficient target node such that the energy consumption of the mobile network is maintained or reduced. This may allow RAN nodes to request an energy-efficient target node that can reduce the energy consumption of the mobile network and avoid target nodes being chosen that are less energyefficient.

[0021] The radio access network entity may be configured to receive one or more signal strength measurements from the user equipment and make the request for energy-efficient handover in dependence on the signal strength measurements). This may allow the network entity to determine when to request handover of the user equipment to a different network entity.

[0022] The radio access network entity may be configured to report energy consumption information and / or load information to the core network control plane entity periodically and / or upon request from the core network control plane entity. This may allow the RAN entity to notify the core network control plane entity of the information or to use a request-response approach.

[0023] The radio access network entity may be configured to report the energy consumption information to the core network control plane entity by sending a message to the core network control plane entity, the message comprising respective information elements corresponding to the core network control plane entity, the radio access network entity and the energy consumption information. This may allow the RAN entity to inform the core network control plane entity of the energy consumption of the RAN entity in an update procedure. The message may be a RAN EC INFORMATION message.

[0024] The radio access network entity may be configured to request a target node to handover the user equipment to by sending a message to the core network control plane entity, the message comprising respective information elements corresponding to the core network control plane entity, the radio access network entity and a request for an energy-efficient handover target. This may allow the RAN entity to request an energy-efficient target node. The message may be a HANDOVER TARGET REQUESTED message. The message may comprise, for each information element, a name, a presence, an information element type and reference and a criticality. This may allow the RAN entity to send relevant information to the core network control plane entity.

[0025] The radio access network entity may be a gNodeB. This may allow the approach to be used in communications networks.

[0026] The core network control plane entity may be an access and mobility management function or an energy management function. This may allow the approach to be used in communications networks. The access and mobility management function is a suitable entity for performing these function, as it communicates with the radio access network. The energy management function is a dedicated network function responsible for monitoring and / or managing the energy consumption of the mobile network and so is suitable for performing these functions as they relate to energy management.

[0027] According to another aspect, there is provided a core network control plane network entity in a mobile network, the core network control plane network entity being in control of multiple nodes of the mobile network and being configured to: request information indicating the energy consumption and / or load of each of the multiple nodes under the control of the core network control plane network entity; generate and maintain energy consumption monitoring information for each of the multiple nodes; receive a request to handover a user equipment from a source node of the multiple nodes to a target node of the multiple nodes; and in response to the request, determine a target node for handover of the user equipment in dependence on the energy consumption monitoring information.

[0028] This may reduce energy consumption in a mobile network operation during mobility by providing a mechanism in the core network control plane that can receive a request from RAN nodes for energy saving-based handover decisions and give the capability to asses and deliver the decision on an optimal target node based on the energy consumption and / or load information of potential RAN nodes.

[0029] The core network control plane network entity may be configured to send an indication of the target node to the source node or to an access and mobility management function of the core network control plane. This may allow handover of the user equipment from the source node to the target node to be initiated.

[0030] The core network control plane entity may be an access and mobility management function. This may allow the approach to be initiated in communication networks. The access and mobility management function is a suitable entity for performing these function, as it communicates with the radio access network.

[0031] The core network control plane entity may be an energy management function. This may allow the approach to be initiated in communication networks. The energy management function is a dedicated network function responsible for monitoring and / or managing the energy consumption of the mobile network and so is suitable for performing these functions as they relate to energy management.

[0032] The energy management function may be configured to receive the energy consumption information and / or load information of radio access network nodes of the multiple nodes from the access management function. This may allow the AMF to receive the information and pass the information to the EMF to make the handover decision.

[0033] The access management function may be configured to receive the energy consumption and / or load information from the multiple nodes directly. This may allow the AMF to make the handover decision. The core network control plane entity may be configured to periodically receive the energy consumption and / or load information from the multiple nodes and / or request the energy consumption and / or load information from the multiple nodes. This may allow the core network control plane entity to be notified of the information or to use a request-response approach.

[0034] The core network control plane entity may be configured to generate and maintain an energy consumption map for each of the multiple nodes based on respective received energy consumption and / or load information from each of the multiple nodes. This may allow the core network control plane entity to monitor the energy consumption of each of the nodes.

[0035] The core network control plane entity may be configured to retrieve a tracking area identity list for the user equipment from a mobility context of the user equipment and a request to select a target node from the tracking area identity list which is most suitable for reducing or maintaining the energy consumption of the network. This may allow the core network control plane entity to identify a suitable target node from the possible nodes that the UE may connect to.

[0036] The core network control plane entity may be configured to request the information indicating the energy consumption and / or load for nodes in the tracking area identity list for the user equipment. This may allow the core network control plane entity to identify a suitable target node from the possible nodes that the UE may connect to.

[0037] The core network control plane entity may be configured to retrieve a respective policy for the nodes in the tracking area identity list, where the policy for prioritization dictates whether to prioritize radio or energy consumption during selection of the target node for handover of the user equipment. This may allow the core network control plane entity to determine whether to prioritize radio or energy consumption for each node during handover.

[0038] The core network control plane entity may be configured to analyse the information indicating the energy consumption and / or load received from the nodes in the tracking area identity list and select a target node which can reduce or maintain a desired energy consumption level of the network at a required wireless link quality according to the policy. This may allow the core network control plane entity to determine whether to prioritize radio or energy consumption for each node during handover.

[0039] The multiple nodes may be radio access network entities. The multiple nodes may be gNodeBs. This may allow the approach to be used in common communication networks.

[0040] According to a further aspect, there is provided a method for implementation at a radio access network entity configured to operate as a source node in a radio access network of a mobile network during a communication session with a user equipment, the radio access network comprising one or more other nodes capable of communicating with the user equipment, the method comprising: reporting energy consumption information and / or load information for the radio access network entity to a core network control plane entity of the mobile network; sending a request to the core network control plane entity for handover of the user equipment from the source node to a target node of the one or more other nodes of the radio access network; receiving, from the core network control plane entity, an indication of a target node to which the user equipment in the communication session with the radio access network entity is to be handed over to; and initiating a handover procedure to transfer the user equipment to the target node.

[0041] This method may provide a mechanism at RAN nodes via which energy consumption can be reduced during handover procedures.

[0042] According to another aspect, there is provided a method for implementation at a core network control plane network entity in a mobile network, the core network control plane network entity being in control of multiple nodes of the mobile network, the method comprising: requesting information indicating the energy consumption and / or load of each of the multiple nodes under the control of the core network control plane network entity; generating and maintaining energy consumption monitoring information for each of the multiple nodes; receiving a request to handover a user equipment from a source node of the multiple nodes to a target node of the multiple nodes; and in response to the request, determining a target node for handover of the user equipment in dependence on the energy consumption monitoring information.

[0043] This method may reduce energy consumption in a mobile network operation during mobility by providing a mechanism in the core network control plane that can receive a request from RAN nodes for energy saving-based handover decisions and give the capability to asses and deliver the decision on an optimal target node based on the energy consumption and / or load information of potential RAN nodes.

[0044] According to a further aspect, there is provided a core network control plane entity in a mobile network, the core network control plane entity being configured to: receive energy consumption and traffic information from multiple network entities in the mobile network; generate a respective monitoring state for each of the multiple network entities based on the received energy consumption and traffic information from each respective network entity of the multiple network entities; and using the monitoring states, analyse the energy consumption and traffic information of the multiple network entities; and if the energy consumption and / or traffic information for one or more of the network entities satisfies one or more criteria, trigger a load balancing event in which the core network control plane entity performs the following steps: based on the received energy consumption and traffic information for the multiple network entities, identify load from one or more of the network entities whose energy consumption and / or traffic information satisfies the one or more criteria and identify one or more target network entities of the multiple network entities for shifting the identified load from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria; and transmit a decision for load balancing to the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria, wherein the decision comprises instructions indicating the one or more target network entities and the load to be shifted from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria to the one or more target network entities.

[0045] This may reduce energy consumption in a mobile network operation by providing a mechanism in the core network control plane that can requests energy consumption and traffic characteristics of RAN and core network entities, monitor the energy consumption of RAN and core network entities and their traffic characteristics, analyze the monitored traffic and energy consumption of network entities to identify load balancing opportunities with the goal of reducing energy consumption, and deliver instructions to RAN and core network entities to balance the load to reduce energy consumption in the mobile network.

[0046] The one or more target entities may be the most suitable network entities for reducing the energy consumption of the mobile network. This may allow load to be redistributed to reduce the energy consumption of the mobile network.

[0047] Each respective monitoring state may be in the form of a graph representing the current energy consumption state of a respective network entity and its respective traffic and load conditions. This may allow the core network control plane entity to monitor the energy consumption of the RAN nodes.

[0048] The energy consumption and / or traffic information may comprise one or more of the following: a number of user equipment served by a network entity, information regarding protocol data unit sessions, information regarding quality of service flows, data volume, data rate, and energy consumption information at different granularities. This may allow loads to be identified that can be shifted to other network entities. The load to be shifted from the one or more network entities may comprise one or more of the following: user equipment load, packet data unit session and data flow. This may be done by, for example, handing over UEs, flows and / or sessions to an optimal target entity in RAN, or to a less loaded UPF in the CN.

[0049] The multiple network entities may be radio access network entities and / or core network entities. This may allow load to be balanced in different types of entities in the network.

[0050] The one or more radio access network entities are gNodeBs. This may allow the approach to be used in communication networks.

[0051] According to a further aspect, there is provided a network entity in a mobile network, the network entity being configured to send energy consumption and traffic condition information for the network entity to the core network control plane entity. This may provide a mechanism at RAN or CN nodes via which energy consumption and traffic information can be provided to a core network control plane entity for load balancing.

[0052] The network entity may be configured to : receive a request for energy consumption and traffic information from a core network control plane entity of the network; and in response to receiving the request, send the energy consumption and traffic condition information for the network entity to the core network control plane entity. This may allow a request-response approach to be used.

[0053] The network entity is configured to periodically send the energy consumption and traffic condition information to the core network control plane entity. This may allow a notify approach to be used.

[0054] The network entity may be configured to send the energy consumption and traffic information by sending a message to the core network control plane entity, the message comprising respective information elements corresponding to the network entity, the core network control plane entity, the energy consumption information and the traffic condition information. The message may be a Core EC and TRAFFIC INFORMATION message.

[0055] The energy consumption information and / or traffic information may comprise one or more of the following: a number of user equipment served by the network entity, information regarding protocol data unit sessions, information regarding quality of service flows, data volume, data rate and energy consumption information at different granularities. This may allow the network entity to inform the core network control plane entity of its energy consumption and traffic information.

[0056] The network entity may be a radio access network entity or a core network entity. This may allow different entities in the mobile network to report their respective information.

[0057] According to a further aspect, there is provided a method for implementation at a core network control plane entity in a mobile network, the method comprising: receiving energy consumption and traffic information from multiple network entities in the mobile network; generating a respective monitoring state for each of the multiple network entities based on the received energy consumption and traffic information from each respective network entity of the multiple network entities; using the monitoring states, analysing the energy consumption and traffic information of the multiple network entities; and if the energy consumption and / or traffic information for one or more of the network entities satisfies one or more criteria, triggering a load balancing event comprising the following steps: based on the received energy consumption and traffic information for the multiple network entities, identifying load from one or more of the network entities whose energy consumption and / or traffic information satisfies the one or more criteria and identify one or more target network entities of the multiple network entities for shifting the identified load from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria; and transmitting a decision for load balancing to the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria, wherein the decision comprises instructions indicating the one or more target network entities and the load to be shifted from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria to the one or more target network entities.

[0058] This method may reduce energy consumption in a mobile network operation by providing a mechanism in the core network control plane that can request energy consumption and traffic characteristics of RAN and core network entities, monitor the energy consumption of RAN and core network entities and their traffic characteristics, analyze the monitored traffic and energy consumption of network entities to identify load balancing opportunities with the goal of reducing energy consumption, and deliver instructions to RAN and core network entities to balance the load to reduce energy consumption in the mobile network.

[0059] According to a further aspect, there is provided a mobile network comprising the radio access network entity and / or network entity and / or core network control plane entity described above.

[0060] According to a further aspect, there is provided one or more computer programs for instructing a computer comprising one or more processors to implement the methods above.

[0061] According to a further aspect there is provided a data carrier storing in non-transitory form the one or more computer programs above.

[0062] BRIEF DESCRIPTION OF THE FIGURES

[0063] Figure 1 schematically illustrates a state-of-the-art handover of a UE performed during mobility.

[0064] Figure 2 schematically illustrates a problem with uneven loads experienced by different network entities.

[0065] Figure 3 schematically illustrates a 3GPP 5G system architecture (TS 23.501).

[0066] Figure 4 schematically illustrates an example of network entities involved in energy-enhanced handovers in a 5G mobile network.

[0067] Figure 5a shows an exemplary procedure for requesting energy consumption information of radio access network nodes.

[0068] Figure 5b shows an exemplary procedure for notifying energy consumption information of radio access network nodes.

[0069] Figure 5c shows an example of a RAN EC INFORMATION message for notifying the core network control plane entity of the energy consumption of a RAN node.

[0070] Figure 6a shows an exemplary procedure for requesting a target base station for handover.

[0071] Figure 6b shows an example of a HANDOVER TARGET REQUESTED message sent from the RAN node to the core network control plane entity. Figure 7a shows an exemplary energy consumption monitoring process.

[0072] Figure 7b shows an exemplary monitoring state in the form of a graph of data volume and data rate vs energy consumption.

[0073] Figure 8 shows an exemplary energy consumption analysis process.

[0074] Figure 9 shows an exemplary communication flow for energy consumption monitoring and a handover procedure.

[0075] Figure 10 shows another exemplary communication flow for energy consumption monitoring and a handover procedure in a mobile network where the management plane receives the energy consumption information from the network entities and the core network control plane retrieves the energy consumption information of the network entities from the management plane.

[0076] Figure 11 schematically illustrates an example of entities in a 3GPP mobile network for implementation of the approach described herein.

[0077] Figure 12 schematically illustrates another example of entities in a 3GPP mobile network for implementation of the approach described herein.

[0078] Figure 13 schematically illustrates a further example of entities in a 3GPP mobile network for implementation of the approach described herein.

[0079] Figure 14 shows an example of the steps of a method for implementation at a RAN entity.

[0080] Figure 15 shows an example of the steps of a method for implementation at a core network control plane entity.

[0081] Figure 16 schematically illustrates an example of some of the entities involved in dynamic energy-aware load-balancing in a 3GPP mobile network.

[0082] Figure 17a schematically illustrates an example of a procedure for requesting energy consumption and traffic characteristics information of radio access network entities.

[0083] Figure 17b schematically illustrates an example of a procedure for notifying energy consumption and traffic characteristics information of radio access network entities.

[0084] Figure 17c shows an example of a RAN EC and TRAFFIC INFORMATION message sent from a RAN node to a core network control plane entity.

[0085] Figure 18a shows an exemplary procedure for requesting energy consumption and traffic characteristics information of core network entities.

[0086] Figure 18b shows an exemplary procedure for notifying energy consumption and traffic characteristics information of core network entities.

[0087] Figure 18c shows an example of a CORE EC and TRAFFIC INFORMATION message sent from a core network entity to a core network control plane entity. Figure 19a shows an exemplary procedure for instructing network nodes to perform load balancing.

[0088] Figure 19b shows an example of a LOAD BALANCE message sent from the core network control plane entity to a RAN or core network entity.

[0089] Figure 20a shows an exemplary process for monitoring the EC and load of network entities.

[0090] Figure 20b shows an exemplary monitoring state in the form of a graph of data volume and data rate vs load and energy consumption.

[0091] Figure 21 shows an exemplary process for analyzing and identifying target entities and load for load balancing in a mobile network.

[0092] Figure 22 shows an exemplary communication flow for energy consumption and traffic monitoring used for load balancing in a mobile network.

[0093] Figure 23 shows an exemplary method for implementation at a core network control plane entity.

[0094] Figure 24 schematically illustrates an example of a network entity.

[0095] DETAILED DESCRIPTION

[0096] Embodiments of the present invention have an overarching goal of reducing energy consumption in a mobile network.

[0097] The embodiments described herein are applicable to methods, devices and mechanisms in communication systems such as 3GPP communication systems.

[0098] Figure 3 schematically illustrates an exemplary deployment of a 3GPP 5G network 300. Although the examples described herein refer to a 5G network, the described examples may also be implemented in different communication networks. The network comprises a plurality of network entities (NEs). The NEs may be network function (NFs), which may be softwarebased. The NEs may alternatively be network apparatus (hardware-based).

[0099] A mobile network comprises a Radio Access Network (RAN) and a Core Network (CN). The RAN handles the wireless aspects, while the CN handles the management and control aspects. Both the RAN and CN have a User Plane (UP) to transmit traffic.

[0100] Network 300 comprises a network slice selection function (NSSF) 301, network exposure function (NEF) 302, network repository function (NRF) 303, policy control function (PCF) 304, unified data management (UDM) 305, application function (AF) 306, network slice-specific authentication and authorization function (NSSAAF) 307 and authentication server function (AUSF) 308. The network comprises an access and mobility management function (AMF) 309. The network comprises a session management function (SMF) 310. The network also comprises a service communication proxy (SCP) 311, a user equipment (UE) 312, an access network (AN) 313 (here a radio access network (RAN)), user plane function (UPF) 314 and data network (DN) 315. In current mobile networks, there are generally no mechanisms via which energy consumption can be reduced during handover procedures or through actively re-balancing the load on RAN and CN entities to reduce the energy consumption in the mobile communication network.

[0101] Embodiments of a first aspect described herein address a technical problem of how to reduce the energy consumption in a mobile network operation through enhancing the handover process with energy-related criteria. These embodiments aim to reduce energy consumption in a mobile network operation during mobility by providing a mechanism in the CN CP that can receive a request from RAN nodes for energy saving-based handover decisions and give the capability to asses and deliver the decision on an optimal target BS based on EC information of potential RAN nodes.

[0102] Embodiments of a second aspect described herein address a technical problem of how to reduce the energy consumption in a mobile network through actively rebalancing the load on RAN and CN entities. These embodiments aim to reduce energy consumption in a mobile network operation by providing a mechanism in the CN CP that can requests EC and traffic characteristics of RAN and CN entities, monitor the EC of RAN and CN entities and their traffic characteristics (such as a number of UEs, data volume, data rate of traffic, etc, i.e., load), analyze the monitored traffic and EC of network entities to identify load balancing opportunities with the goal of reducing EC, and deliver instructions to RAN and CN entities to balance the load to reduce EC. This may be done by, for example, handing over UEs, flows and / or sessions to an optimal target entity in RAN, or to a less loaded UPF in the CN.

[0103] The first aspect will now be described in more detail.

[0104] Figure 4 schematically illustrates network entities involved in energy-enhanced handovers in an exemplary 5G mobile network. The approach may also be used in other types of communication networks. The network 400 comprises a UDM 401 , PCF 402, AMF 403, SMF 404, UPF 405 and DN 406. The network comprises four BSs 407, 408, 409, 410, which in this example are gNBs. A UE 411 can partake in a communication session with any of the BSs 407-410.

[0105] A CN CP entity that is responsible for managing access related aspects, namely AMF 401, with the help of the procedures shown in Figure 5a, as explained below, periodically requests, or is notified of, the current EC of RAN network entities such as the BSs 407-410 as shown in Figure 5b. In this example, the EC information is received from the BSs directly. In other examples, an Energy Management Function (EMF) may receive the EC information from an AMF, if EMF is supported in the network. An EMF is a dedicated network function responsible for monitoring and managing the energy consumption of the mobile network.

[0106] The BSs 407-410 may report energy consumption information and / or load information to the AMF periodically and / or upon request from the core network control plane entity.

[0107] Figures 5a and 5b show an exemplary procedure for requesting and notifying EC information of RAN nodes in a RAN of a mobile network. In these examples, the AMF receives the EC information and determines the target node for the handover.

[0108] The elementary procedure in Figures 5a and 5b is a RAN EC update procedure. The purpose of the RAN EC update procedure is to notify the respective entity in the core network control plane such as AMF or EMF, the EC of the RAN node (BS). The procedure may use non UE-associated signalling.

[0109] In Figure 5a, a RAN node 501 receives a request 503 from a CN CP node 502 for its EC information. In this example, the CN CP node 502 requests the information from the RAN node 501 by sending a RAN EC INFORMATION REQUEST message to the RAN node 501. In response, the RAN node 501 sends its EC information to the CN CP node 502, as shown at 504. The CN CP node 502 then performs an EC monitoring process, as illustrated at 505. This process will be described in more detail below.

[0110] In Figure 5b, a RAN node 501 notifies a CN CP node 502 of its EC information. It may do this periodically. The RAN node 501 sends its EC information to the CN CP node 502, as shown at 506, as a RAN EC INFORMATION NOTIFY message. The CN CP node 502 then executes an EC monitoring process, as illustrated at 505.

[0111] Alternatively, the EC information may be sent along with periodic measurement reports from RAN entities to reduce signalling overhead.

[0112] Figure 5c shows an example of a RAN EC INFORMATION message sent from a RAN node (BS) to the CN CP entity (e.g. AMF). Similar messages can be sent from other RAN entities / BSs in the RAN to the CN CP entity (e.g. AMF). The RAN EC INFORMATION NOTIFY message in Figure 5b may have the same form.

[0113] The message comprises respective information elements corresponding to the CN CP node, the RAN node and the EC information. The message comprises, for each information element, a name (for example, CN CP Node ID), a presence (in this example, M), an information element type and reference (such as 9.3.3.1.TS 38.413 for the CN CP node) and a criticality (in this example, YES).

[0114] In this example, the AMF is configured to receive the energy consumption and / or load information from the multiple nodes directly. In examples where the information is received at the EMF, wherein the EMF can receive the EC information and / or load information of the RAN nodes from the AMF.

[0115] As well as requesting EC information, the CN CP node 502 may alternatively or additionally request load information from the RAN node 501 in the same way, either by using the same or different messages as for the EC information. The requested load may be configurable by the CN CP entity. For example, the load may be, for each attached UE, a traffic profile or rate.

[0116] This provides a mechanism in the RAN to report EC and / or load measurements periodically and / or upon request to the CN CP entity. Where applicable (e.g. for the request-response embodiment shown in Figure 5a) this also provides a mechanism in the Core CP (e.g., at the AMF or EMF) to request EC information of RAN nodes.

[0117] Figure 6a shows a procedure for requesting a target BS for handover. The elementary procedure in Figure 6a is Handover Target Request. The purpose of the handover target request procedure is to request the CN CP node (e.g. AMF) for a Target node (e.g. BS) when the Source node decides to initiate a handover for a UE. The procedure may use UE-associated signalling. The message is HANDOVER TARGET REQUESTED.

[0118] In Figure 6a, a RAN node 501 sends a request 601 to a CN CP node 502 for an energy-efficient target node. In this example, the RAN node 501 requests the target node for handover by sending a HANDOVER TARGET REQUESTED message to the CN CP node 502.

[0119] The CN CP node 502 performs an EC analysis process, shown at 602, which will be described in more detail below, using the received EC information from the RAN nodes in the RAN network and selects an energy-efficient target node. The CN CP entity 502 then notifies the RAN node 501 of the handover target node, in this example by sending a HANDOVER TARGET message to the RAN node 501. Figure 6c shows an example of a HANDOVER TARGET REQUESTED message sent to the CN CP entity (e.g. AMF) from the source RAN node (in this example, RAN node 501).

[0120] The message comprises respective information elements corresponding to the CN CP entity, the RAN entity and a request for an energy-efficient handover target. The message comprises, for each information element, a name (for example, CN CP Node ID), a presence (in this example, M), an information element type and reference (such as 9.3.3.1.TS 38.413 for the CN CP node) and a criticality (in this example, YES).

[0121] This provides a mechanism in the RAN to request an energy-efficient target node for handing over a UE during mobility.

[0122] The CN CP (for example, the AMF or EMF) generates and maintains an EC map of each RAN entity based on the received EC and / or load information with an EC monitoring process shown in Figure 7a.

[0123] When a UE connected to the network undergoes mobility / starts moving the source RAN node (e.g., SBS, SgNB) can decide based on the UE’s received signal strength, or more other criteria, if a handover is necessary. When a handover has been decided, the Source node sends a request the CN CP entity (e.g., AMF) to identify the Target RAN node (e.g., TBS, TgNB) using the procedure shown in Figure 6a.

[0124] Figure 7a schematically illustrates an EC monitoring process 701 at the CN CP entity, which may be the AMF 403 of Figure 4. BSs 407-410 each send their EC information to the AMF 403. The information is generally shown at 702.

[0125] Figure 7b shows an exemplary EC monitoring state for one of BSs in the form of a graph of data volume and data rate vs energy consumption. The EC monitoring process uses such a graph for each of the BSs 407-410.

[0126] Figure 8 shows an example of the EC analysis process. The purpose of the EC analysis process is to analyze the monitoring maps that represent the current EC of RAN nodes to identify the Target node for handover of a UE. The process provides a response to the Source node on the Target node to the HANDOVER TARGET REQUESTED message received from the Source node in the Handover Target Request Procedure described above with reference to Figures 6a and 6b. The procedure may use UE-associated signalling.

[0127] Upon receiving a request from BS 407 for a Target RAN node, as indicated at 801, the AMF can retrieve the UE’s mobility context, as shown at 802, and retrieve the UE’s Tracking Area Identity (TAI) list from the mobility context, as indicated at 803. The TAI list can be used in the EC Analysis Process (located either in the AMF or EMF) shown in Figure 8 with a request to select a Target RAN node (e.g., TBS, TgNB) which is most suitable in terms of reducing the EC of the network. The EC Analysis Process can request the EC monitoring information for the RAN nodes in the TAI list from the EC monitoring process and retrieve a policy for prioritization from a respective CN CP function (such as PCF) where the policy dictates, for example, whether to prioritize radio or EC during handover. The policy may originate in the core network. The policy may be defined by a mobile network operator. The policy may be received from a policy control function.

[0128] A list of nodes in the area may also be retrieved from other CN entities. The EC information may be requested for nodes in the list of nodes in the area and the TAI list.

[0129] The energy-enhanced handover mechanism in the RAN and Core CP of a mobile network considers both the energy status of the involved entities and the status of the wireless link when making decisions about handover. The EC analysis process analyzes the EC of the RAN nodes in the TAI list and selects a Target RAN node (e.g. TBS) which can reduce or maintain a desired EC level of the network at required wireless link quality as per the policy of the network. The EC analysis process outputs the selected Target RAN node (e.g., TBS, TgNB) to the AMF. The AMF can inform the Source RAN node (e.g., SBS, SgNB) about the Target RAN node (e.g., TBS, TgNB) to which the UE should be handed over.

[0130] This provides a mechanism in the CN CP (e.g., at the AMF or EMF) to generate and maintain an EC monitoring information of RAN nodes (shown in Figure 7a) and a mechanism in the CN CP (e.g., at the AMF) to receive the request for handover decision and deliver the energy-optimal Target node (e.g., TBS, TgNB) for handover to the Source node (e.g., SBS, SgNB) (shown in Figure 8).

[0131] Some further exemplary embodiments of the first aspect will now be described.

[0132] In the example shown in Figure 9, a UE 901 is in a communication session with a source node, source radio access technology (SRAT) node 902. The UE 901 is handed over to an energy-efficient target node, TRAT node 903, using a selection procedure at the CN CP entity 904, as described below.

[0133] In a step 0, the SRAT node 902 and the target radio access technology (TRAT) node 903 send their respective EC information to the CN CP entity 904 in a respective RAN EC INFORMATION message, as shown at 905 and 906 respectively. As shown at 907, the CN CP entity 904 (for example, the AMF or EMF) in the 5G CN performs EC monitoring. The CN CP entity 904 may continuously monitor the EC of all of the RAN entities in the network. In step 1, as shown at 908, the UE measures the received signal strength of signals sent between the UE 901 and the SRAT node 902. In step 2, as shown at 909, the UE 901 sends a signal strength measurement report to the source RAN entity that is serving the UE (i.e. SRAT node 902). In step 3, as shown at 910, the source RAN entity analyzes the UE’s measurement report and verifies if the signal quality received by UE is below some pre-defined threshold and decides to handover the UE when the condition is met. In step 4, as shown at 911 , the source RAN entity requests the CN for information on a target RAN entity to which the UE is to be handed over. In this example, it does this by sending a HANDOVER TARGET REQUESTED message. In step 5, as shown at 912, upon receiving the request for a target RAN entity, the responsible CN CP entity 904 analyzes the EC of the potential target RAN entities that can serve the UE. In step 6, as shown at 913, the CN CP entity 904 selects a suitable target RAN entity that either reduces or maintains the desired EC of the network. In step 7, as shown at 914, the CN CP entity 904 delivers the information on selected target RAN entity to the source RAN entity for handover. In this example, it does this by sending a HANDOVER TARGET response message to the SRAT node 902.

[0134] In steps 8-17.2, the UE is handed over to the target RAN entity. This may be done using conventional approaches. In this example, in step 8, as shown at 915, the SRAT node 902 sends a handover request to the TRAT node 903.

[0135] Step 9, as shown at 916 is an admission control step. In step 10, as shown at 917, the TRAT node 903 acknowledges the handover request by sending a HANDOVER REQUEST ACKNOWLEDGED message to the SRAT node 902. In step 11, as shown at 918, handover of the UE 901 is initiated to transfer the UE from the SRAT node 902 to the TRAT node 903.

[0136] In step 12, as shown at 919, buffered data and new data from UPF(s) is delivered from the SRAT node 902 to the TRAT node 903. In step 13, as shown at 920, the UE is detached from the old cell of SRAT node 902 and synchronised to the new cell of TRAT node 902. In step 14, as shown at 921, user data is sent between the CN CP entity and the SRAT and TRAT nodes. In step 15, as shown at 922, user data is buffered from the source node. In step 16, as shown at 923, RAN handover is completed. In steps 17.1 and 17.2, as shown at 924 and 925 respectively, user data is sent from the CN CP entity 904 to the TRAP node 903 and then on to the UE 901.

[0137] Figure 10 shows another example of the first aspect. In this example, in addition to UE 901, SRAT node 902, TRAP node 903 and CN CP entity 904, a MP entity 930 is shown.

[0138] In a step 0, the SRAP node 902 and the FRAP node 903 send their respective EC information to the MP entity 905 in respective RAN EC INFORMATION messages, as shown at 1001 and 1002 respectively. In step 1, the MP entity 930 sends the RAN EC information received from each RAN entity to the CN CP entity 904 (e.g., the AMF), as shown at 1003. In step 2, as shown at 1004, the CN CP entity 904 performs the EC monitoring process. The CN CP entity 904 may continuously monitor the EC of all of the RAN entities in the network. In step 3, as shown at 1005, the UE measures the received signal strength of signals sent between the UE 901 and the SRAT node 902. In step 4, as shown at 1006, the UE 901 sends a signal strength measurement report to the source RAN entity that is serving the UE (i.e. SRAT node 902). In step 5, as shown at 1007, the source RAN entity analyzes the UE’s measurement report and verifies if the signal quality received by UE is below some pre-defined threshold and decides to handover the UE when the condition is met. In step 6, as shown at 1008, the source RAN entity requests the CN for information on a target RAN entity to which the UE is to be handed over. In this example, it does this by sending a HANDOVER TARGET REQUESTED message. In step 7, as shown at 1009, upon receiving the request for a target RAN entity, the responsible CN CP entity 904 analyzes the EC of the potential target RAN entities that can serve the UE. In step 8, as shown at 1010, the CN CP entity 904 selects a suitable target RAN entity that either reduces or maintains the desired EC of the network. In step 9, as shown at 1011, the CN CP entity 904 delivers the information on selected target RAN entity to the source RAN entity for handover. In this example, it does this by sending a HANDOVER TARGET RESPONSE message to the SRAT node 902.

[0139] In steps 10-19.2, the UE is handed over to the target RAN entity. This may be done using conventional approaches. In this example, in step 10, as shown at 1012, the SRAT node 902 sends a handover request to the TRAP node 903.

[0140] Step 11, as shown at 1013 is an admission control step. In step 12, as shown at 1014, the TRAP node 903 acknowledges the handover request by sending a HANDOVER REQUEST ACKNOWLEDGED message to the SRAT node 902. In step 13, as shown at 1015, handover of the UE 901 is initiated to transfer the UE from the SRAT node 902 to the TRAP node 903.

[0141] In step 14, as shown at 1016, buffered data and new data from UPF(s) is delivered from the SRAT node 902 to the TRAP node 903. In step 15, as shown at 1017, the UE is detached from the old cell of SRAT node 902 and synchronised to the new cell of TRAP node 902. In step 16, as shown at 1018, user data is sent between the CN CP entity and the SRAT and TRAP nodes. In step 17, as shown at 1019, user data is buffered from the source node.

[0142] In step 18, as shown at 1020, RAN handover is completed. In steps 19.1 and 19.2, as shown at 1021 and 1022 respectively, user data is sent from the CN CP entity 904 to the TRAP node 903 and then on to the UE 901.

[0143] A further example will now be described with reference to F igure 11. Network 1100 comprises an NRF 1101, PCF 1102, a network data analytics function (NWDAF) 1103 and an application function (AF) 1104. The network comprises an AMF 1105, an SME 1106, a NEF 1107 and a UDM 1108. The network also comprises a UE 1109, a AN 1110 (here a radio access network (RAN)), UPF 1111 and DN 1112.

[0144] This embodiment shows that AMF 1105 handles the EC based handover in the CN. The AMF 1105 periodically requests or is notified of the current EC of RAN nodes, which as gNBs (BSs). In some implementations, the EC information may be sent along with periodic measurement reports from RAN nodes. The AMF 1105 generates and maintains a monitoring state (for example, a graph) of each RAN node based on this information in the EC monitoring process.

[0145] A UE 1109 connected to the network is under mobility / starts moving. The SgNB in RAN 1110 decides based on the UE’s received signal strength if a handover is necessary. If so, the SgNB sends a request to the AMF 1105 for identifying the TgNB. The AMF 1105 retrieves the UE’s TAI list from its mobility context and passes it to the EC analysis process at the AMF 1105 with a request to select the TgNB which is most suitable in terms of reducing the EC of the network. The EC analysis process outputs the TgNB and the AMF informs the SgNB of the TgNB which should be used for handover. The SgNB then handovers the UE to the selected TgNB.

[0146] In another example, which will be described with reference to Figure 12, a network 1200 comprises an NRF 1201, PCF 1202, NWDAF 1203 and AF 1204. The network comprises an AMF 1205, an SME 1206, an NEF 1207 and a UDM 1208. The network also comprises a UE 1209, a AN 1210 (here a radio access network (RAN)), UPF 1211 and DN 1212. In this example, an EMF 1213 is part of AMF 1205.

[0147] In this example, the AMF 1205, together with the EMF 1213, handles the EC based handover in the CN. The EMF is located as a sub-unit in the AMF.

[0148] The EMF 1213 periodically requests / is notified the current EC of RAN nodes. The EC information may in some implementations be sent along with periodic measurement reports from the RAN nodes. The EMF 1213 generates and maintains a monitoring state (for example, a graph) of each RAN node based on this information during the EC monitoring process.

[0149] A UE connected to the network is under mobility / starts moving. The SgNB decides based on the UE’s received signal strength if a handover is necessary. The SgNB sends a request to the AMF 1205 for identifying the TgNB. The AMF retrieves the UE’s TAI list from its mobility context and passes it on to EMF with a request for Target gNB. The EMF 1213 uses the EC analysis process to select the TgNB which is most suitable in terms of reducing the EC of the network. The EMF 1205 outputs the target gNB to the AMF 1205 and the AMF 1205 informs the SgNB of the selected TgNB which should be used for handover. The SgNB then handovers the UE to the selected TgNB.

[0150] In another example, which will be described with reference to Figure 13, a network 1300 comprises an NRF 1301, PCF 1302, EMF 1303, AF 1304, NWDAF 1305, AMF 1306, SMF 1307, an NEF 1308 and a UDM 1309. The network also comprises a UE 1310, a AN 1311 (here a radio access network (RAN)), UPF 1312 and DN 1313.

[0151] In this embodiment, the EMF 1303 handles the EC based handover in the CN with the help of the AMF 1306. In this example, the proposed features in the CN are located in the EMF. The management plane (MP) is shown at 1314.

[0152] The EMF 1303 periodically requests or is notified of the current EC of RAN nodes. The EC information may be sent along with periodic measurement reports from RAN nodes. The EMF 1303 generates and maintains a monitoring state (for example, a graph) of each RAN node based on this information using the EC monitoring process.

[0153] A UE connected to the network is under mobility / starts moving. The SgNB decides based on the UE’s received signal strength if a handover is necessary. The SgNB sends a request to the AMF 1306 for identifying the TgNB. The AMF 1306 retrieves the UE’s TAI list from its mobility context and passes it on to the EMF 1303 with a request for a target gNB. The EMF 1303 uses the EC analysis process to select the TgNB which is most suitable in terms of reducing the EC of the network. The EMF 1303 outputs the target gNB to the AMF 1306. The AMF 1306 informs the SgNB of the TgNB which should be used for handover. The SgNB then handovers the UE to the selected TgNB.

[0154] Figure 14 shows exemplary steps of a method 1400 for implementation at a radio access network entity configured to operate as a source node in a radio access network of a mobile network during a communication session with a user equipment. The radio access network comprising one or more other nodes capable of communicating with the user equipment. The method comprises, at step 1401, reporting energy consumption information and / or load information for the radio access network entity to a core network control plane entity of the mobile network. At step 1402, the method comprises sending a request to the core network control plane entity for handover of the user equipment from the source node to a target node of the one or more other nodes of the radio access network. At step 1403, the method comprises receiving, from the core network control plane entity, an indication of a target node to which the user equipment in the communication session with the radio access network entity is to be handed over to. At step 1404, the method comprises initiating a handover procedure to transfer the user equipment to the target node.

[0155] Figure 15 shows exemplary steps of a method 1500 for implementation at a core network control plane network entity in a mobile network. The core network control plane network entity is in control of multiple nodes of the mobile network. The method comprises, at step 1501, requesting information indicating the energy consumption and / or load of each of the multiple nodes under the control of the core network control plane network entity. At step 1502, the method comprises generating and maintaining energy consumption monitoring information for each of the multiple nodes. At step 1503, the method comprises receiving a request to handover a user equipment from a source node of the multiple nodes to a target node of the multiple nodes. At step 1504, the method comprises, in response to the request, determining a target node for handover of the user equipment in dependence on the energy consumption monitoring information.

[0156] The approaches described above provide a mechanism in RAN to report EC measurements periodically, and / or upon request, to the AMF and to request an energy-efficient TBS (e.g., TgNB) for handing over a UE during mobility.

[0157] Also provided is a mechanism in the core CP (for example, the AMF or EMF) to request EC information of RAN nodes and to generate and maintain an EC Monitoring information of RAN nodes. It also provides a mechanism for the Core CP (for example, AMF) to receive a request for a handover decision and deliver the energy-optimal TBS (e.g., TgNB) for handover to the SBS (e.g., SgNB).

[0158] This can enable mobile network operators to reduce and maintain the desired level of energy consumption in the network during mobility.

[0159] Embodiments of a second aspect described herein aim to reduce energy consumption in a mobile network operation by providing a mechanism in the CN CP that can requests EC and traffic characteristics of RAN and CN entities, monitor the EC of RAN and CN entities and their traffic characteristics, such as a number of UEs, data volume, data rate of traffic, etc. i.e., load, analyze the monitored traffic and EC of network entities to identify load balancing opportunities with the goal of reducing EC, and deliver instructions to RAN and CN entities to balance the load to reduce EC, for example handover of UEs / Hows / sessions / etc., to an optimal target entity in the RAN or to a less loaded UPF in the CN.

[0160] The second aspect will now be described in more detail.

[0161] Figure 16 schematically illustrates network entities involved in dynamic energy-aware load-balancing in an exemplary 5G mobile network. The approach may also be used in other types of mobile communication networks. The network 1600 comprises a UDM 1601, PCF 1602, AMF 1603, SMF 1604, UPF 1605 and DN 1606. The network comprises four BSs 1608, 1609, 1610, 1611, which in this example are gNBs. The UEs shown generally at 1611 can partake in a communication session with any of the BSs 1607-1610. In this example, UE 1612 is in a communication session with BS 1607.

[0162] Figures 16 shows the entities involved in the dynamic energy-aware load-balancing in a 5G mobile network. The Core Control Plane, e.g., AMF or EMF periodically requests / receives the EC and traffic conditions experienced by the respective entities in the RAN and Core Network in the form of e.g., reports through the procedure shown in the Figures 17a, 17b and 18a.

[0163] Figures 17a and 17b show an exemplary procedure for requesting and notifying EC and traffic information of RAN entities in a RAN of a mobile network. In these examples, the AMF receives the EC and traffic information.

[0164] The elementary procedure in Figures 17aand 17b is a RAN EC and TRAFFIC INFORMATION update procedure. The purpose of the RAN EC and TRAFFIC INFORMATION update procedure is to notify the CN CP of the EC of the RAN code and its current traffic conditions. The procedure may use non UE-associated signalling.

[0165] EC data sent to the CN CP may include, for example, the energy consumption of the RAN entity in Joules. The traffic information may include, for example, a number of UEs, protocol data unity (PDU) sessions, QoS Flows, data Volume and Data Rate of each QoS Flow, etc.

[0166] In Figure 17a, a RAN node 1701 receives a request 1703 from a CN CP node 1702 for its EC and traffic information. In this example, the CN CP node 1702 requests the information from the RAN node 1701 by sending a RAN EC AND TRAFFIC INFORMATION REQUEST message to the RAN node 1701. In response, the RAN node 1701 sends its EC and traffic information to the CN CP node 1702, as shown at 1704. The CN CP node 1702 then performs a load monitoring process, as illustrated at 1705. This process will be described in more detail below.

[0167] In Figure 17b, a RAN node 1701 notifies a CN CP node 1702 of its EC and traffic information. It may do this periodically. The RAN node 1701 sends its EC and traffic information to the CN CP node 1702, as shown at 1706, as a RAN EC AND TRAFFIC INFORMATION NOTIFY message. The CN CP node 1702 then performs a load monitoring process, as illustrated at 1705.

[0168] Alternatively, the EC AND TRAFFIC information may be sent along with periodic measurement reports from RAN entities to reduce signalling overhead.

[0169] Figure 17c shows an example of a RAN EC and TRAFFIC INFORMATION message sent from a RAN node (BS) to the CN CP entity (e.g. AMF). Similar messages can be sent from other RAN entities / BSs in the RAN to the CN CP entity (e.g. AMF). The RAN EC AND TRAFFIC INFORMATION NOTIFY message in Figure 17b may have the same form.

[0170] The message comprises respective information elements corresponding to the CN CP node, the RAN node, the EC information and the traffic information. The message comprises, for each information element, a name (for example, CN CP Node ID), a presence (in this example, M), an information element type and reference (such as 9.3.3. l.TS 38.413 for the CN CP node) and a criticality (in this example, YES).

[0171] In this example, the AMF is configured to receive the energy consumption and traffic information from the multiple nodes directly. In examples where the information is received at the EMF, wherein the EMF can receive the EC information and traffic information of the RAN nodes from the AMF. Figures 18a and 18b show an exemplary procedure for requesting and notifying EC and traffic information of CN entities of a mobile network. In these examples, the AMF receives the EC and traffic information.

[0172] In Figures 18a and 18b, the elementary procedure is core EC and TRAFFIC INFORMATION update. The message is Core EC and TRAFFIC INFORMATION. The purpose of the Core EC and TRAFFIC INFORMATION Update procedure is to notify the Core CP the EC of the Core Network nodes and their current traffic conditions. The procedure may use non UE-associated signalling.

[0173] EC data sent to the CN CP may include, for example, the energy consumption of the RAN entity in Joules. The traffic information may include, for example, a number of UEs, protocol data unity (PDU) sessions, QoS flows, data volume and data rate of each QoS flow, etc.

[0174] In Figure 18a, a CN node 1801 receives a request 1803 from a CN CP node 1802 for its EC and traffic information. In this example, the CN CP node 1802 requests the information from the CN node 1801 by sending a Core EC AND TRAFFIC INF ORMATION REQUEST message to the CN node 1801. In response, the CN node 1801 sends its EC and traffic information to the CN CP node 1802, as shown at 1804. The CN CP node 1802 then performs a load monitoring process, as illustrated at 1805. This process will be described in more detail below.

[0175] In F igure 18b, a CN node 1801 notifies a CN CP node 1802 of its EC and traffic information. It may do this periodically . The CN node 1801 send its EC and traffic information to the CN CP node 1802, as shown at 1806, as a Core EC AND TRAFFIC INFORMATION NOTIFY message. The CN CP node 1802 then performs a load monitoring process, as illustrated at 1805.

[0176] Alternatively, the EC AND TRAFFIC information may be sent along with periodic measurement reports from CN entities to reduce signalling overhead.

[0177] Figure 18c shows an example of a Core EC and TRAFFIC INFORMATION message sent from a CN node to the CN CP entity (e.g. AMF). Similar messages can be sent from other CN entities to the CN CP entity (e.g. AMF). The Core EC AND TRAFFIC INFORMATION NOTIFY message in Figure 18b may have the same form.

[0178] The message comprises respective information elements corresponding to the CN CP node, the CN node, the EC information and the traffic information for the CN node. The message comprises, for each information element, a name (for example, CN CP Node ID), a presence (in this example, M), an information element type and reference (such as 9.3.3.1.TS 38.413 for the CN CP node) and a criticality (in this example, YES).

[0179] In this example, the AMF is configured to receive the energy consumption and traffic information from the CN nodes directly. In examples where the information is received at the EMF, wherein the EMF can receive the EC information and traffic information of the CN nodes from the AMF.

[0180] Figure 19a shows an exemplary procedure for instructing RAN and CN nodes to perform load balancing.

[0181] A CN CP node 1902 performs an EC based load balancing process, as indicated at 1904. This process will be described in more detail below. One or more RAN nodes 1902 and / or one or more core CP or UP nodes 1903 in the mobile network are sent a LOAD BALANCE message from the CN CP node 1902. In Figure 19a, the elementary procedure is LOAD BALANCE. The purpose of the LOAD BALANCE procedure is to instruct one or more source nodes in the mobile network to perform load balancing and provide supporting information, such as the target nodes to which the loads should be shifted and what traffic is to be offloaded to which target node. The procedure may use non UE-associated signalling.

[0182] Figure 19b shows an example of a LOAD BALANCE message sent from the CN CP node 1902 to the RAN and / or CN nodes (which may be CP or UP nodes of the CN).

[0183] In this example, the message comprises respective information elements corresponding to the source RAN node, the target RAN node, the CN CP node, the source CN node, the target CN node and the traffic information. The message comprises, for each information element, a name (for example, CN CP Node ID), a presence (in this example, M), an information element type and reference (such as 9.3.3.1.TS 38.413 for the CN CP node) and a criticality (in this example, YES).

[0184] The TRAFFIC INFORMATION data may comprise one or more of the following: a number of UEs, PDU sessions, QoS Flows, data volume and data rate of each QoS flow.

[0185] The CN CP (for example, the AMF or EMF) generates and maintains a map of each RAN or CN entity based on the received EC and traffic information with a load monitoring process shown in Figure 20a.

[0186] Figure 20a schematically illustrates the load monitoring process 2001 at the CN CP entity, which may be the AMF 1603 of Figure 16. BSs 1607-1610 each send their EC and traffic information to the AMF 403. The information is generally shown at 2002.

[0187] One or more core network entities, such as one or more core CP NFs, shown generally at 2003, and one or more core UP entities, shown generally at 2004, may also send EC and traffic information to the CN CP entity for input to the load monitoring process.

[0188] The load monitoring process receives the EC information and traffic status reports and through the monitoring process, monitors the status of each node in the network with regards to EC and various traffic characteristics.

[0189] The load monitoring process may generate and maintain monitoring states for each of the entities from which it receives EC and traffic information: that is, one or more RAN entities and / or one or more core CP entities and / or one or more core UP entities. The monitoring states may be in the form of graphs that represents the current EC state of each node and its traffic and load conditions.

[0190] The traffic information may indicate one or more of the following: a number of UEs served by a node, data volume, data rate of the traffic, etc.

[0191] Figure 20b shows an exemplary EC monitoring state for one of BSs in the form of a graph of data volume and data rate vs load and EC.

[0192] When the EC and / or the traffic information indicates that a load experienced by a node satisfies one or more criteria (which may be a predetermined criteria, such as the load experienced by a node exceeding a pre-defmed threshold), a load balancing event is triggered by the load monitoring process. An example of an EC based load balancing process 2100 is shown in Figure 21. The process analyzes and identifies target entities and load for load balancing. Upon receiving a trigger to perform load balancing from one or more nodes of the network in which one or more criteria have been satisfied (trigger = load balance node X), the EC based load balancing process analyses the EC and traffic report of the respective entity for which the one or more criteria were satisfied that are maintained by the load monitoring process and selects a target entity which is most suitable in terms of reducing the EC and identifies the load (for example, UEs, PDU sessions, flows, etc.) that are to be shifted. The EC based load balancing process outputs this information for the respective one or more network entities that triggered the load balancing event. The control plane can inform the respective entity to carry out the load balancing using the procedure shown in the Figure 19a.

[0193] The output of the load balancing process comprises the source network entities (for example, SBSs) from which load is to be shifted, the target network entities (for example TBSs) to which the load is to be shifted, and the load to be shifted (UE, PDU session, flow, etc.).

[0194] In Figure 21, the process 2100 starts at 2101. At 2102, the CN CP entity requests EC and traffic information from multiple network entities (in this example, the EC or Bss and core NFs) and traffic reports. Alternatively, the CN CP entity may be notified of the information. This may be done at, for example, a periodic, dynamic or random frequency. At 2103, the process determined whether the EC and traffic information indicates whether a load of one or more of the network entities satisfies one or more criteria. In this example, the process determines from the EC and traffic information whether the EC and / or load is above a threshold. If the one or more criteria are satisfied for one or more of the network entities, an event trigger is raised by those one or more network entities (e.g. BSx and / or NFx) to perform load balancing. The process requests the monitoring information for multiple network entities in the mobile network (for example, multiple Bss and / or NFs of the CN) from the EC monitoring process 2105 and receives the EC monitoring information for each of the multiple network entities. At 2106, the EC and traffic reports of the monitoring information are analyzed and at 2107, one or more target network entities (for example, BSs and / or NFs) are identified to which load can be shifted from the one or more network entities that triggered the load balancing event. At 2108, load balancing instructions are sent to the source network entities from which load is to be shifted that informs them of the target network entities (for example, BSs and / or NFs) to which the load is to be shifted. At 2109, the load is shifted from the source network entities to the target network entities. At 2110, the EC of the mobile network is reduced. The process can then be repeated at 2111.

[0195] Figure 22 shows a communication flow for an exemplary embodiment of the second aspect.

[0196] In the example shown in Figure 22, one or more UEs 2201 are in a communication session with a source node, SRAT node 2202. One or more of the UEs 2201 can be handed over to a target node, TRAT node 9223, using a load balancing procedure at the CN CP entity 2204, as described below. The network also comprises one or more other CN CP entities 2205 and a DN 2206.

[0197] In a step 0, the SRAT node 2202 and the TRAT node 2203 send their respective EC information to the CN CP entity 2204 in a respective RAN EC and TRAFFIC INFORMATION message, as shown at 2207 and 2208 respectively. The one or more other CN CP entities 2205 can also send their respective EC and traffic information to the CN CP entity 2204 in a Core EC and TRAFFIC INFORMATION message, as shown at 2209. In other words, the RAN and CN entities measure and send their EC and traffic information, which provides information on the operating load in the respective entities to a CN CP entity 2205 (for example, an AMF or EMF).

[0198] In step 1, as shown at 2210, the CN CP entity 2204 (for example, the AMF or EMF) in the 5G CN performs EC and load monitoring. The CN CP entity 2210 may continuously monitor the EC and load of all of the RAN and CN entities in the network. The CN CP entity monitors the EC with respect to load for the RAN and CN entities through the load monitoring process, as described above.

[0199] In step 2, as shown at 2211, the DN 2206 exchanges data with the one ormore UEs 2201 in a respective communication session with the SRAT node 2202. In step 3, as shown at 2212, the CN CP entity 2204 analyzes the received EC information and traffic information and identifies if a load balancing event should be triggered through the load monitoring process. In step 4, as shown at 2213, a load balancing trigger is raised. Loading balancing is triggered if the EC and / or traffic information received from one or more of the RAN or CN nodes satisfies one or more criteria. The criteria may be predetermined criteria. For example, a criterion may be that a load at the node has exceeded a threshold.

[0200] In step 5, as shown at 2214, if a load balancing event is triggered, the load(s) to be shifted is / are identified by the EC based load balancing process at the CN CP entity 2204. In step 6, as shown at 2215, the target network entity or entities in the RAN and / or the CN to which the load is to be shifted is / are identified by the EC based load balancing process at the CN CP entity 2204.

[0201] In steps 7.1 and 7.2, as shown at 2216 and 2217 respectively, instructions for balancing the load are delivered to the corresponding source RAN and CN entities respectively with the information of the target entities and the loads that are to be shifted.

[0202] In step 8, as shown at 2218, the SRAT node 2202 sends a request to shift load to the identified TRAT node 2203. Step 9, as shown at 2219, is an admission control step. In step 10, as shown at 2220, the received request to shift load is acknowledged by the TRAT node 2203 by sending a REQUEST ACKNOWLEDGED message to the SRAT node 2202.

[0203] In step 11.1 , as shown at 2221 , handover of one or more of the UEs 2201 is initiated to transfer UE load from the SRAT node 2202 to the TRAT node 2203. In step 11.2, as shown at 2222, load is shifted between two or more of the CN functions 2205. The source nodes shift the indicated loads to the identified target nodes.

[0204] In step 12, as shown at 2223, buffered data and new data from UPF(s) is delivered from the SRAT node to the TRAT node(s) 2203.

[0205] In step 13, as shown at 2224, the UE is detached from the old cell of SRAT node 2202 and synchronised to the new cell of TRAT node 2203.

[0206] In step 14, as shown at 2225, user data is sent between the CN CP entity and the SRAT and / or TRAT nodes.

[0207] In step 15, as shown at 2226, user data is buffered from the source node.

[0208] In step 16, as shown at 2227, RAN load balancing is completed.

[0209] In a further example, the AMF handles the EC based load balancing in the CN and the CN CP entity that performs the abovementioned features is the AMF in a 5G Mobile Network. The mobile network has the same architecture as shown in Figure 11.

[0210] In this example, the AMF periodically requests the current EC and traffic information of RAN and CN entities (e.g., gNBs, BSs, UPFs, etc.). The load monitoring process receives this information from the AMF and Core NFs. It generates and maintains a monitoring state (for example, a graph of each RAN node and CN NF) based on this information. The load monitoring process checks if an EC or load threshold has been reached or crossed by any RAN nodes and / or any CN NF nodes and generates an event trigger when the conditions are met. The EC based load balancing process receives the event trigger and analyzes the EC and traffic information of BSs / NFs maintained by the load monitoring process to select the target BSs and NFs which are most suitable in terms of reducing the EC of the network through load balancing. The EC based load balancing process outputs the source and target BSs and NFs, and the respective load (UEs, PDU session, flows, etc.,) to be shifted from the source BS and NF to the target BSs and NFs. The AMF informs the source BS and CN NF which triggered the event to balance its load with the TBSs and target CN NFs and informs the load (UEs, PDU session, flows, etc.,) that is to be shifted. The source BS and CN NF then shift the load to Target BSs and NFs.

[0211] In another example, the AMF together with the EMF handles the EC based load balancing in the Core Network. The CN CP entity that performs the abovementioned features is an EMF, which is located as a sub-unit in the AMF. In this example, the mobile network has the same architecture as shown in Figure 12.

[0212] The EMF periodically requests the current EC and traffic information of RAN and CN entities (e.g., gNBs, BSs, UPF, etc.) via the AMF. The load monitoring process in the EMF receives this information. The load monitoring process generates and maintains a monitoring state (for example, a graph) for each RAN node and CN NF based on this information. The load monitoring process checks if the EC or load threshold has been reached or crossed by any RAN nodes and / or any CN NF nodes and generates an event trigger when the conditions are met. The EC based load balancing process receives the event trigger and analyzes the EC and traffic information of BSs / NFs maintained by the load monitoring process to select the target BSs and NFs which are most suitable in terms of reducing the EC of the network through load balancing. The EC based load balancing process outputs the source and target BSs and NFs, and the respective load (UEs, PDU session, flows, etc.,) to be shifted from source BS and NFs. The EMF via AMF informs the source BS and the CN NFs which triggered the event to balance its load with the TBSs and target CN NFs and informs the load (UEs, PDU session, flows, etc.,) that are to be shifted. The source BS and CN NF then shift the load to target BSs and target NFs.

[0213] In a further embodiment, an EMF handles the EC based load balancing in the Core Network with the help of AMF. The CN CP entity that performs the abovementioned features is an EMF, which in this example is a separate NE to the AMF. In this example, the mobile network has the same architecture as shown in Figure 13.

[0214] The EMF periodically requests the current EC and traffic information of RAN and CN entities (e.g., gNBs, BSs, UPF, etc.), for RAN entities via the AMF. The load monitoring process in the EMF receives this information . It generates and maintains a monitoring state (for example, a graph) of each RAN node and CN NF based on this information. The load monitoring process checks if the EC or load threshold has been reached or crossed by any RAN nodes and / or any CN NF nodes and generates an event trigger when the conditions are met. The EC based load balancing process receives the event trigger and analyzes the EC and traffic information of BSs / NF s maintained by the load monitoring process to select the target BSs and NFs which are most suitable in terms of reducing the EC of the network through load balancing. The EC based load balancing process outputs the source and target BSs and NFs, and the respective load (UEs, PDU session, flows, etc.,) to be shifted from the source BS and NFs. EMFthe informs the source BS (via AMF) and CN NF which triggered the event to balance their load with the TBSs and target CN NFs and informs the load (UEs, PDU session, flows, etc.,) that are to be shifted. The source BS and CN NF then shift the load to the target BSs and target NFs.

[0215] Figure 23 shows exemplary steps of a method for implementation at a core network control plane entity in a mobile network. The method comprises, at step 2301, receiving energy consumption and traffic information from multiple network entities in the mobile network. At step 2302, the method comprises generating a respective monitoring state for each of the multiple network entities based on the received energy consumption and traffic information from each respective network entity of the multiple network entities. At step 2303, the method comprises using the monitoring states, analysing the energy consumption and traffic information of the multiple network entities. At step 2304, the method comprises, if the energy consumption and / or traffic information for one or more of the network entities satisfies one or more criteria, triggering a load balancing event. The load balancing event may comprise the steps shown at 2305 and 2306. At step 2305, the method comprises, based on the received energy consumption and traffic information for the multiple network entities, identifying load from one or more of the network entities whose energy consumption and / or traffic information satisfies the one or more criteria. At step 2306, the method comprises identifying one or more target network entities of the multiple network entities for shifting the identified load from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria, transmitting a decision for load balancing to the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria, wherein the decision comprises instructions indicating the one or more target network entities and the load to be shifted from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria to the one or more target network entities.

[0216] The approaches described above provide a mechanism in the core CP to save energy in a mobile network through energy- enhanced load balancing in RAN and CN. The approach provides a mechanism in the core CP to retrieve the EC and traffic characteristics of RAN and CN entities, as shown in Figures 17a, 17b, 18a and 18b.

[0217] Also provided is a mechanism to analyze the EC and traffic characteristics of RAN and CN entities and generate event triggers for load balancing (as shown in the example of Figure 20a), amechanismto identify the target RAN and CN entities for shifting the load from identified source entities (as shown in the example of Figure 21) and a mechanism to deliver the decision for load-balancing with instructions on target RAN and CN entities, and the load (for example, UE and UE traffic) that is to be be shifted (as shown in the example of Figure 19a).

[0218] The approaches described herein can enable mobile network operators to reduce and maintain the desired level of energy consumption in the network and / or to optimally utilize the resources in the RAN and CN through efficient load balancing. Effective load balancing can ensure efficient operation of mobile networks, but also reduce the overall energy consumption of the mobile networks.

[0219] Figure 24 shows an example of a network entity 2400. The network entity may operate as any network entity described herein (for example, as a RAN entity or a CN entity, such as a CN CP entity). Entity 2401 is a computing entity. Entity 2402 is a command and control entity. These entities are logical entities. In practice they may each be provided by one or more physical devices such as servers and data stores, and the functions of two or more of the entities may be provided by a single physical device. In some implementations, the entities may be cloud-based. Each physical device implementing an entity may comprise a processor and a memory. The network entity may also comprise a transceiver for transmitting and receiving data. The memory stores in a non-transient way code that is executable by the processor to implement the respective entity in the manner described herein.

[0220] Although the examples described herein refer to a 5G network, the described examples may also be implemented in a different communication network in the future.

[0221] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention. The project leading to this application has received funding from the European Union's Horizon research and innovation programme under grant agreement No 101139120.

Claims

CLAIMS1. A radio access network entity (407, 501, 902) configured to operate as a source node in a radio access network of a mobile network (400) during a communication session with a user equipment (411, 901, 1109, 1209, 1310), the radio access network comprising one or more other nodes (408, 409, 410, 903) capable of communicating with the user equipment, the radio access network entity (407) being configured to: report (1401) energy consumption information and / or load information for the radio access network entity to a core network control plane entity (403, 502, 904, 1105, 1213, 1303) ofthe mobile network; send (1402) a request to the core network control plane entity for handover of the user equipment from the source node to a target node of the one or more other nodes of the radio access network; receive (1403), from the core network control plane entity, an indication of a target node (408, 903) to which the user equipment in the communication session with the radio access network entity is to be handed over to; and initiate (1404) a handover procedure to transfer the user equipment to the target node.

2. The radio access network entity as claimed in claim 1 , wherein the request for handover of the user equipment comprises a request for an energy-efficient target node such that the energy consumption of the mobile network is maintained or reduced.

3. The radio access network entity as claimed in claim 1 or claim 2, wherein the radio access network entity is configured to receive one or more signal strength measurements from the user equipment and make the request for energy-efficient handover in dependence on the signal strength measurement(s).

4. The radio access network entity as claimed in any preceding claim, wherein the radio access network entity is configured to report energy consumption information and / or load information to the core network control plane entity periodically and / or upon request from the core network control plane entity.

5. The radio access network entity as claimed in any preceding claim, wherein the radio access network entity is configured to report the energy consumption information to the core network control plane entity by sending a message to the core network control plane entity, the message comprising respective information elements corresponding to the core network control plane entity, the radio access network entity and the energy consumption information.

6. The radio access network entity as claimed in any preceding claim, wherein the radio access network entity is configured to request a target node to handover the user equipment to by sending a message to the core network control plane entity, the message comprising respective information elements corresponding to the core network control plane entity, the radio access network entity and a request for an energy-efficient handover target.

7. The radio access network entity as claimed in claim 5 or claim 6, wherein the message comprises, for each information element, a name, a presence, an information element type and reference and a criticality.

8. The radio access network entity as claimed in any preceding claim, wherein the radio access network entity is a gNodeB.

9. The radio access network entity as claimed in any preceding claim, wherein the core network control plane entity is an access and mobility management function (403, 1105) or an energy management function (1213, 1303).

10. A core network control plane network entity (403, 502, 904, 1105, 1213, 1303) in a mobile network (400), the core network control plane network entity being in control of multiple nodes of the mobile network and being configured to:26request (1501) information indicating the energy consumption and / or load of each of the multiple nodes (407, 408, 409, 410, 501, 902, 903) under the control of the core network control plane network entity; generate and maintain (1502) energy consumption monitoring information for each of the multiple nodes; receive (1503) a request to handover a user equipment (411, 901, 1109, 1209, 1310) from a source node (407, 902) of the multiple nodes to a target node (408, 903) of the multiple nodes; and in response to the request, determine (1504) a target node for handover of the user equipment in dependence on the energy consumption monitoring information.

11. The core network control plane network entity as claimed in claim 10, wherein the core network control plane network entity is configured to send an indication of the target node to the source node or to an access and mobility management function (403, 1105) of the core network control plane.

12. The core network control plane entity as claimed in claim 10 or claim 11 , wherein the core network control plane entity is an access and mobility management function (403, 1105).

13. The core network control plane entity as claimed in claim 10 or claim 11, wherein the core network control plane entity is an energy management function (1213, 1303).

14. The core network control plane entity as claimed in claim 13, wherein the energy management function is configured to receive the energy consumption information and / or load information of radio access network nodes of the multiple nodes from the access management function.

15. The core network control plane entity as claimed in claim 12, wherein the access management function is configured to receive the energy consumption and / or load information from the multiple nodes directly.

16. The core network control plane entity as claimed in any of claims 10 to 15, wherein the core network control plane entity is configured to periodically receive the energy consumption and / or load information from the multiple nodes and / or request the energy consumption and / or load information from the multiple nodes.

17. The core network control plane entity as claimed in any of claims 10 to 16, wherein the core network control plane entity is configured to generate and maintain an energy consumption map for each of the multiple nodes based on respective received energy consumption and / or load information from each of the multiple nodes.

18. The core network control plane entity as claimed in any of claims 10 to 17, wherein the core network control plane entity is configured to retrieve a tracking area identity list for the user equipment from a mobility context of the user equipment and a request to select a target node from the tracking area identity list which is most suitable for reducing or maintaining the energy consumption of the network.

19. The core network control plane entity as claimed in claim 18, wherein the core network control plane entity is configured to request the information indicating the energy consumption and / or load for nodes in the tracking area identity list for the user equipment.

20. The core network control plane entity as claimed in claim 18 or claim 19, wherein the core network control plane entity is configured to retrieve a respective policy for the nodes in the tracking area identity list, where the policy for prioritizationdictates whether to prioritize radio or energy consumption during selection of the target node for handover of the user equipment.

21. The core network control plane entity as claimed in claim 20, wherein the core network control plane entity is configured to analyse the information indicating the energy consumption and / or load received from the nodes in the tracking area identity list and select a target node which can reduce or maintain a desired energy consumption level of the network at a required wireless link quality according to the policy.

22. The core network control plane entity as claimed in any of claims 10 to 21, wherein the multiple nodes are radio access network entities (407, 408, 409, 410, 501, 902, 903).

23. The core network control plane entity as claimed in claim 22, wherein the multiple nodes are gNodeBs.

24. A method (1400) for implementation at a radio access network entity (407, 501, 902) configured to operate as a source node in a radio access network of a mobile network (400) during a communication session with a user equipment (411, 901, 1109, 1209, 1310), the radio access network comprising one or more other nodes capable of communicating with the user equipment, the method comprising: reporting (1401) energy consumption information and / or load information for the radio access network entity to a core network control plane entity (403, 502, 904, 1105, 1213, 1303) of the mobile network; sending (1402) a request to the core network control plane entity for handover of the user equipment from the source node to a target node of the one or more other nodes of the radio access network; receiving (1403), from the core network control plane entity, an indication of a target node (408, 903) to which the user equipment in the communication session with the radio access network entity is to be handed over to; and initiating (1404) a handover procedure to transfer the user equipment to the target node.

25. A method (1500) for implementation at a core network control plane network entity (403, 502, 904, 1105, 1213, 1303) in a mobile network (400), the core network control plane network entity being in control of multiple nodes of the mobile network, the method comprising: requesting (1501) information indicating the energy consumption and / or load of each of the multiple nodes under the control of the core network control plane network entity; generating and maintaining (1502) energy consumption monitoring information for each of the multiple nodes; receiving (1503) a request to handover a user equipment (411, 901, 1109, 1209, 1310) from a source node (407, 902) of the multiple nodes to a target node (408, 903) of the multiple nodes; and in response to the request, determining (1504) a target node for handover of the user equipment in dependence on the energy consumption monitoring information.

26. A core network control plane entity (1105, 1213, 1303, 1603, 1702, 1802, 1901, 2204) in a mobile network (1600), the core network control plane entity being configured to: receive (2301) energy consumption and traffic information from multiple network entities (1607, 1608, 1609, 1610, 1701, 1801, 1902, 1903, 2202, 2203, 2205) in the mobile network; generate (2302) a respective monitoring state for each of the multiple network entities based on the received energy consumption and traffic information from each respective network entity of the multiple network entities; using the monitoring states, analyse (2303) the energy consumption and traffic information of the multiple network entities; andif the energy consumption and / or traffic information for one or more of the network entities satisfies one or more criteria, trigger (1504) a load balancing event in which the core network control plane entity performs the following steps: based on the received energy consumption and traffic information for the multiple network entities, identify (2305) load from one or more of the network entities whose energy consumption and / or traffic information satisfies the one or more criteria and identify one or more target network entities of the multiple network entities for shifting the identified load from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria; and transmit (2306) a decision for load balancing to the one or more of the network entities (2202) in which the energy consumption and / or traffic information satisfies the one or more criteria, wherein the decision comprises instructions indicating the one or more target network entities (2203) and the load to be shifted from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria to the one or more target network entities.

27. The core network control plane entity as claimed in claim 26, wherein the one or more target entities is / are the most suitable network entities for reducing the energy consumption of the mobile network.

28. The core network control plane entity as claimed in claim 26 or claim 27, wherein each respective monitoring state is in the form of a graph representing the current energy consumption state of a respective network entity and its respective traffic and load conditions.

29. The core network control plane entity as claimed in any of claims 26 to 28, wherein the energy consumption and / or traffic information comprises one or more of the following: a number of user equipment served by a network entity, information regarding protocol data unit sessions, information regarding quality of service flows, data volume, data rate, and energy consumption information at different granularities.

30. The core network control plane entity as claimed in any of claims 26 to 29, wherein the load to be shifted from the one or more network entities comprises one or more of the following: user equipment load, packet data unit session and data flow.

31. The core network control plane entity as claimed in any of claims 26 to 30, wherein the multiple network entities are radio access network entities and / or core network entities.

32. The core network control plane entity as claimed in claim 31, wherein the multiple entities comprise one or more radio access network entities, wherein the one or more radio access network entities are gNodeBs.

33. A method (2300) for implementation at a core network control plane entity (1105, 1213, 1303, 1603, 1702, 1802, 1901, 2204) in a mobile network (1600), the method comprising: receiving (2301) energy consumption and traffic information from multiple network entities (1607, 1608, 1609, 1610, 1701, 1801, 1902, 1903, 2202, 2203, 2205) in the mobile network; generating (2302) a respective monitoring state for each of the multiple network entities based on the received energy consumption and traffic information from each respective network entity of the multiple network entities; using the monitoring states, analysing (2303) the energy consumption and traffic information of the multiple network entities; and if the energy consumption and / or traffic information for one or more of the network entities satisfies one or more criteria, triggering (2304) a load balancing event comprising the following steps:29based on the received energy consumption and traffic information for the multiple network entities, identifying (2305) load from one or more of the network entities (2202) whose energy consumption and / or traffic information satisfies the one or more criteria and identify one or more target network entities (2203) of the multiple network entities for shifting the identified load from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria; and transmitting (2306) a decision for load balancing to the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria, wherein the decision comprises instructions indicating the one or more target network entities and the load to be shifted from the one or more of the network entities in which the energy consumption and / or traffic information satisfies the one or more criteria to the one or more target network entities.

Images