Methods, apparatus and computer programs

Abstract

A first radio access node comprising: means for sending to a second radio access node, a first request for information on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access node associated with one or more offloading actions; and means for receiving from the second radio node one or more messages comprising information on the energy cost associated with one or more of the one or more offloading actions.

Description

[0001]METHODS, APPARATUS AND COMPUTER PROGRAMS TECHNICAL FIELD Various example embodiments relate generally to methods, apparatus, system and computer programs and in particular, but not exclusively, methods, ap- paratus, system and computer programs relating to energy cost. BACKGROUND A communication network can be seen as a facility that enables commu- nications between two or more communication devices, or provides communica- tion devices access to a data network. A mobile or wireless communication net- work is one example of a communication network. Such communication networks operate in according with standards such as those provided by 3GPP (Third Gen- eration Partnership Project) or ETSI (European Telecommunications Standards In- stitute). Examples of standards are the so-called 5G (5th Generation) standards provided by 3GPP and future standards such as 6G and beyond. BRIEF DESCRIPTION Some example embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essen- tial features of the embodiments of this disclosure, nor are they intended to be used to limit the scope thereof. Other features, aspects, and elements will be readily ap- parent to a person skilled in the art in view of this disclosure. According a first aspect, there is provided a first radio access node com-prising: means for sending to a second radio access node, a first request for infor- mation on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access node associated with one or more of-floading actions; and means for receiving from the second radio access node one ormore messages comprising information on the energy cost associated with one or more of the one or more offloading actions. Other optional features of the first aspect may be seen from the depend-ent claims which are dependent on claim 1.According to a second aspect, there is provided a method comprising: sending to a second radio access node, a first request for information on an energy cost, the energy cost being the energy cost of one or more distributed units of thesecond radio access node associated with one or more offloading actions; and re-ceiving from the second radio access node one or more messages comprising infor- mation on the energy cost associated with one or more of the one or more offload- ing actions. The method may comprise receiving from the second radio access node, prior to the one or more offloading actions, information reporting an initial energy cost associated with all distributed units of the second radio access node. The method may comprise determining an effect of one or more of theone or more offloading actions using the information reporting the initial energycost and the information on the energy cost associated with one or more of the one or more offloading actions. The method may be performed by a first radio access node. The first radio access node may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one pro- cessor, cause the apparatus at least to provide one or more of the methods of the second aspect. According a third aspect, there is provided second radio access node comprising: means for receiving from a first radio access node, a first request for information on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access node associated with one or more of-floading actions; and means for sending to the first radio access node one or moremessages comprising information on the energy cost associated with one or more of the one or more offloading actions. Other optional features of the third aspect may be seen from the de- pendent claims which are dependent on claim 20. According a fourth aspect, there is provided a method comprising: re-ceiving from a first radio access node, a first request for information on an energycost, the energy cost being the energy cost of one or more distributed units of thesecond radio access node associated with one or more offloading actions; and sending to the first radio access node one or more messages comprising infor- mation on the energy cost associated with one or more of the one or more offload- ing actions. The method may comprise collecting information about the energy costof the one or more distributed units from the one or more distributed units. The first request may comprises a list of one or more cells of the secondradio access node and the method may comprise determining the one or more dis-tributed units based on the list of one or more cells of the second radio access node. The method may comprise communicating between a centralized unitof the second radio access node and the one or more distributed units via an F1interface. The method may be performed by a second radio access node. The second radio access node may comprise at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to provide one or more of the methods ofthe fourth aspect.According to a fifth aspect, there is provided a first radio access node comprising: means for sending to a second radio access node a first request com- prising information about a plurality of different energy cost levels, each of the plu- rality of different energy cost levels being associated with a different granularity of the second radio access node, the first request further comprising a request for in- formation on an energy cost at one or more of the different energy cost levels; and means for receiving, from the second radio access node, one or more messages providing the requested information on the energy cost at one or more of the plu- rality of different energy cost levels. Other optional features of the fifth aspect may be seen from the depend- ent claims which are dependent on claim 26. According to a sixth aspect, there is provided a method comprising: sending to a second radio access node a first request comprising information about a plurality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of the second radio access node, the first request further comprising a request for information on an energycost at one or more of the different energy cost levels; and receiving, from the sec-ond radio access node, one or more messages providing the requested information on the energy cost at one or more of the plurality of different energy cost levels. Each of the different energy cost levels may be associated with a report-ing priority. The one or more messages providing the requested information on theenergy cost may provide the requested information on one or more of the different energy cost levels having a highest reporting priority and the reporting of which is supported by the second radio access node. The plurality of different energy cost levels may comprise one or moreof: an energy cost level at a node level of the second radio access node; at a level of one or more cells of the second radio access node; or at a level of one or more dis- tributed units of the second radio access node. One or more of the one or more messages may comprise informationabout the respective energy cost at two or more of the plurality of different energy cost levels. The respective energy cost at one of the two or more levels may be de-fined with respect to the respective energy cost at another of the two or more lev- els. The method may be performed by a first radio access node. The first radio access node may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one pro- cessor, cause the apparatus at least to provide one or more of the methods of the sixth aspect. According to a seventh aspect, there is provided a second radio accessnode comprising: means for receiving from a first radio access node a first requestcomprising information about a plurality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granular- ity of the second radio access node, the first request further comprising a request for information on an energy cost at one or more of the different energy cost levels; and means for sending to the first radio access node, one or more messages provid- ing the requested information on the energy cost at one or more of the plurality of different energy cost levels. Other optional features of the seventh aspect may be seen from the de- pendent claims which are dependent on claim 32. According to an eighth aspect, there is provided a method comprising:receiving from a first radio access node a first request comprising information about a plurality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of the second radio access node, the first request further comprising a request for information on anenergy cost at one or more of the different energy cost levels; and sending to thefirst radio access node, one or more messages providing the requested information on the energy cost at one or more of the plurality of different energy cost levels. The method may comprise receiving from a third radio access node asecond request comprising a request for information on an energy cost at one or more of the different energy cost levels; and sending to the third radio access node, one or more messages providing the requested information on the energy cost at one or more of the plurality of different energy cost levels, one or more of which is at different energy cost level different to the information provided to the first ac- cess node. The method may be performed by a second radio access node. The second radio access node may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to provide one or more of the methods of the eighth aspect. According to a ninth aspect, there is provided a first radio access node comprising: means for selecting one or more of a plurality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of a second radio access node, the selecting being based onone or more characteristics of one or more user equipment to be offloaded fromthe first radio access node to the second radio access node; means for sending to the second radio access node a first request for information of an energy cost asso- ciated with the offloading of the one or more user equipment from the first radio access node to the second radio access node, the energy cost being one or more ofthe selected one or more of the plurality of different energy cost levels; and meansfor receiving, from the second radio access node, one or more messages providing the requested information on the energy cost at one or more of the selected one or more of the plurality of different energy cost levels. According to a tenth aspect, there is provided a method comprising: se- lecting one or more of a plurality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of a sec- ond radio access node, the selecting being based on one or more characteristics of one or more user equipment to be offloaded from the first radio access node to the second radio access node; sending to the second radio access node a first request for information of an energy cost associated with the offloading of the one or more user equipment from the first radio access node to the second radio access node, the energy cost being one or more of the selected one or more of the plurality of different energy cost levels; and receiving, from the second radio access node, one or more messages providing the requested information on the energy cost at one or more of the selected one or more of the plurality of different energy cost levels. The method may be performed by a first radio access node. The first radio access node may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one pro- cessor, cause the apparatus at least to provide one or more of the methods of the tenth aspect. In general, any of the above described features may be used in conjunc- tion with one or more different aspects. One or more of the following features may be used in conjunction with one or more of the first to tenth aspects. The first request may comprise information about a plurality of differ- ent energy cost levels including an energy cost associated the one or more distrib- uted units of the second access node, each of the plurality of different energy cost levels being associated with a different granularity of the second radio access node. The plurality of different energy cost levels may further comprises one or more of an energy cost level at a node level of the second radio access node or at a level of one or more cells of the second radio access node. Each of the different energy cost levels may be associated with a report- ing priority. The first request may further comprise a request for information on an energy cost at two or more of the different energy cost levels including the energy cost of the one or more distributed units. One or more messages may further comprise information on the energy cost at one or more of the plurality different energy cost levels in addition to the energy costs of the one or more distributed units. The one or more messages may comprise an indication as to the respec- tive energy cost level associated with the information on the respective energy cost. The first request may comprise configuration information relating to reporting of the energy cost of the one or more distributed units. The configuration information relating to the reporting of the energy cost may indicate one of: reporting of the energy cost periodically; or one time re- porting of the energy cost. The first request may comprise a request for data collection. One or more messages may comprise one or more of: a data collection response; or a data collection update message. The data collection may comprise data collection for one or more ma-chine learning models. One or more of the first request or the one or more messages may be exchanged via an Xn interface between the first radio access node and the second radio access node. One or more of the first radio access node or the second radio access node may comprise a next generation radio access node. One or more of the one or more messages may comprise information about the respective energy cost of two or more of the distributed units. One or more of the one or more messages may comprise summed infor- mation about the energy cost of two or more of the distributed units. The first request may comprise a list of one or more cells of the secondradio access node. According to another aspect, there is provided a computer readable me-dium comprising program instructions stored thereon for performing at least oneof the above methods. According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least one of the above methods. According to an aspect, there is provided a non-volatile tangible memory medium comprising program instructions stored thereon for performing at least one of the above methods. In the above, many different aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above. Various other aspects are also described in the following detailed de- scription and in the attached claims.LIST OF THE DRAWINGSIn the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which Fig.1 shows an example of a communication network to which exam- ples disclosed herein may be applied; Fig.2 shows an example of a source node and two target nodes; Fig.3 shows schematically cell, distributed unit, and node level; Fig. 4 shows an example of a first procedure;Fig. 5 shows an example of a second procedure;Figs. 6A and B show an example of a third procedure;Figs. 7A and B show an example of a fourth procedure;Figs. 8A and B show an example of a fifth procedure;Figs.9 to 13 show first to fifth methods of some embodiments; and Fig. 14 shows an example of an apparatus.DESCRIPTION OF EMBODIMENTS The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodi- ment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embod- iments. Further, when a particular feature, structure, or characteristic is described in connection of an embodiment, it is within the knowledge of one skilled in the art to apply such feature, structure, or characteristic in connection with other embod- iments whether or not explicitly described. It shall be understood that although the terms “first,” “second” and the like may be used herein to describe various ele-ments, these elements should not be limited by these terms. These terms are onlyused to distinguish one element from another. For the purposes of the present disclosure, the phrases “at least one of A or B”, “at least one of A and B”, and “A and / or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). Embodiments described may be implemented in a communication net- work, such as any of the following radio access technologies (RATs): Worldwide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile com- munications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, commu- nication within the communication network may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multi- ple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiple (OFDM), and / or Discrete Fourier Transform spread OFDM (DFT-s- OFDM). As used herein, the term “network device” or “network node” refers to a node in a communication network via which user equipment may access the net- work and / or which is capable of controlling radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network de- vice may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device. Moreover, in connection with a split radio access network (RAN), the network device may refer to a centralised unit (CU) of a base station and / or a dis- tributed unit (DU) of a base station. There may also be radio units (RU). A RU maybe provide as part of a DU. An interface between CU and DU (CP) may be referredto as an F1 interface in NR. An interface between CU -UP and CU- CP may be re-ferred to as an E1 interface in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node) operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. Insome embodiments, the DUs may comprise e.g. a radio link control (RLC) layer,medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence pro- tocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are possible too. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation. The term “terminal device” refers to any end device that may be capableof wireless communication. By way of example, a terminal device may be referredto as a communication device, user equipment (UE), a Subscriber Station (SS), or aMobile Station (MS). The terminal device may include a mobile phone, a cellularphone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones a tablet, a wearable terminal device, a personal digital assistant (PDA), portable com- puters, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, USB dongles, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device op- erating on commercial and / or industrial wireless networks, and the like. A term “resource”, as used herein, may refer to radio resources in time domain, in frequency domain, in space domain, and / or in code domain. Some ex- amples of resources include e.g. a physical resource block (PRB), a radio frame, a subframe, a time slot, a sub band, a frequency region, a sub-carrier, a beam, etc. The term “transmission” and / or “reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources. Fig.1 illustrates an example of a communication network to which ex- amples disclosed herein may be applied. The communication network or a cellular communication network may comprise a network node 110 providing one or more cells, such as cell 100, and a network node 112 providing one or more other cells, such as cell 102. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. The cell may define a coverage area or a service area of the corre- sponding access node. The network node 110 may provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless ac- cess may comprise downlink (DL) communication from the network node to the UE 120 and uplink (UL) communication from the UE 120 to the network node. Ex- amples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment. There may be a plurality of UEs 120, 122 in the system. Each of themmay be served by the same or by different network nodes 110, 112. UE may beconfigured with dual connectivity (DC), wherein the UE, e.g. UE 120, may be con- nected to multiple network nodes 110, 112. The UEs 120, 122 may communicate with each other, in case device-to-device (D2D) communication interface is estab- lished between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or ve- hicle-to-vehicle (V2V), for example. In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifica- tions call such an interface as X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called Xn interface. The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifica- tions specify the core network as an evolved packet core (EPC), and the core net- work may comprise e.g. a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signalling connections between the terminal devices and the core network. The gateway node may handle data routing in the core net- work and to / from the terminal devices. The 5G specifications specify the core net- work as a 5G core (5GC). The 5G core may comprise e.g. an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signal- ling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, se- curity context management. The UPF node may support packet routing and for- warding, packet inspection and quality of service (QoS) handling, for example. Reference is made to Figure 2 which schematically shows a coveragearea of a first RAN node 1. The first RAN node 1 has a second RAN node 2 and athird RAN node 3 as neighbour nodes. One or more UEs may be offloaded from the coverage area of the first RAN node 1 to one or more cells of the second RAN node 2 and / or one more cells of the third RAN node 3. In some embodiments, one or more UEs may be offloaded from a sourcenode to a target node. Examples of offloading comprise one or more of handover orload balancing. Reference is made to Figure 3 which shows a first RAN node, gNB1, a second RAN node, gNB2 and a third RAN node, gNB3. The first RAN node comprises a gNB-CU-CP a first DU1, a second DU2and a third DU2. The gNB-CU-CP controls the first DU1, the second DU2, and the third DU2. DU 1 provides cells 1 to n which are neighbour cells to the second RANnode (gNB-2).DU 2 provides cells 1 to n which are neighbour cells to the third RANnode (gNB-3).DU 3 provides cells 1 to n which are neighbour cells to the third RANnode (gNB-3)The source node or first radio access node may be a NG-RAN node. The terms source node, first radio access node, RAN node and first NG-RAN node are used interchangeably. It should be appreciated that a NG-RAN node is one exampleof a radio access node and other embodiments may use any other suitable radioaccess node. The second radio access node or target node may be a second NG-RAN node. The terms target node, second radio access node, RAN node and second NG- RAN node are used interchangeably. In the following examples, reference is made to an NG-RAN node. It should be appreciated that a NG-RAN node is one exampleof a radio access node and other embodiments may use any other suitable radioaccess node. Energy cost is an incurred energy cost to serve the one or more UEs of- floaded from a first RAN node to a different RAN node. In some embodiments, this energy cost may be reported at one more different granularity levels. For example, the energy cost may be reported at thenode level. Node level EC is a coarse level energy cost measurement, Node level ECis measured or determined overall at the node level. For example the node level EC may be determined based on all the network elements / functions (for example all the DUs and the CU) which make up the RAN node. In some embodiments, a finer granularity level of energy cost may be supported. For example, the energy cost may be supported at a granularity of per cell or per DU level. The DU level EC is the incurred EC of one or more of the DUs of the node to which the one or more UE are offloaded. The measurements or determination ofthe DU level EC may be based on one or more of the DUs of the node.The cell level EC is the incurred EC of one or more of a cell of the node to which the one or more UE are offloaded. The measurements or determination ofthe cell level EC may be based the parts of the node supporting the cell, for exampleone or more RUs. The granularity level or levels which are supported may be dependent on the capabilities of the target RAN node to which the one or more UEs are to beoffloaded. For example, the energy cost may be measured to a granularity of one ormore of the target cell level, the target DU level; or target node to which the UE(s)are handed over. The granularity level of the energy cost measurement may determinethe accuracy with which the source node assesses the impact of the offloaded traffic on the target. The energy consumption of a node may comprise an energyconsumption of all the network functions (NF) or network elements that constitutethe gNB. In a split architecture, the node level EC includes the energy consump-tion from the DU, and CU. This may include the CU control plane (CP) and / or theCU user plane (UP). In a typical deployment serving a large area, there are multipleRUs served by a DU and of the order of 80% of the total energy consumption maybe due to the RU energy consumption. When an offloading action is initiated, UE(s) are offloaded to one ormore target cell(s) in one or more DU(s). The source node may need to evaluate theimpact of the offloading action to the target node to which the one or more UEs areoffloaded. For example, if a source node wants to save energy by switching off a cell and offloading one or more UEs attached to that cell to a target node, it can beevaluated if there is an overall energy saving. For example the source node mayevaluate the difference between the of the total EC after and before the offloading. This may be based on measurements made at both the source node and the targetnode. If the difference is positive, it means that the total EC increased after the of-floading and therefore it was not a good decision. If the difference is negative, it means that the total EC decreased after the offloading (and therefore the offloading was a good decision). This comparison may be used to determine the performance of an ac-tion. In some embodiments, the source node may evaluate the difference be-tween the of the total EC before and after the offloading. In this example, a positivedifference means the decision was good and a negative difference means the deci- sion was bad. In some embodiments, energy cost may have a granularity that corre-sponds with the action in order to better evaluate the performance of the action. For example for cell level decisions (such as a handover event for offloading trafficfrom a cell to another cell) the energy cost metric may be on a cell level granularity.For node level measured EC at a target node, it is possible that the measurement also includes EC due to other concurrent offloading actions from other neighbouring nodes and also due to changes in the UE traffic characteristicsof one or more currently served UEs in the target node. This may lead to an inaccu-rate mapping of a cost metric to the particular decision. When the EC is measured at a node level, the probability of such inaccuracy may increase because the nodeitself consists of many DUs, each of which hosts a plurality of RUs. The larger thegranularity over which an EC measurement is performed, the more likely that thecost does not reflect the impact of the offloading action itself. When the energy cost is measured at the DU level, this may improve theaccuracy of the evaluation. This may be particularly advantageous in architectures which use split level architectures. When the EC is measured at the cell level, this may improve the accuracyof the evaluation. However, such cell level measurements of EC cost may not alwaysbe supported by the target node. For example, physical hardware resources (e.g.,Radio Unit) may be shared across two or more cells, which makes the per-cell ECmeasurement difficult. In deployments with no resource pooling, cell-level EC reporting by the target node may provide an accurate assessment of the impact of an offloading ac- tion handing over a number of UEs (load) to the target node. In some embodiments,the cell level EC may be estimated based on other measurements such as PRB uti-lization. In some embodiments, the source node may request one or more differ-ent EC granularities from the target node. In some embodiments, the source node may determine the list of re- quested granularity levels based on one or more offloading characteristics of the load (for example of the one or more UEs to be handed over). The one or moreoffloading characteristics may comprise one or more of: the number of UEs to beoffloaded; the radio conditions in the target cell; traffic characteristics; and / or thelike. A source node may identify if the difference between the list of served cells and the list of cells that are configured as neighbours is significant or not in the context of EC exchange. For example, if a neighbour (target) node serves 3 cells and all the 3 cells are configured as neighbour cells in the source node, then the source node may identify that the node level energy cost is suitable. In another ex- ample, if a neighbour node serves 100 cells but only three cells are configured as neighbour cells in a source node, then the source node can identify that node-level energy cost is not suitable. Accordingly, a source node may trigger a different gran- ularity for reporting of EC. For example, considering the number of UEs to be offloaded, a sourcenode may configure the preferred EC cost reporting for different cells as follows:- If the number of UEs offloaded to a given target cell is relatively small,the source node may select a cell-level granularity. The lowest granularity may bepreferred in this example to determine the difference in the energy cost. -If the number UEs offloaded to a given target cell is relatively high, thesource node may select a node-level granularity or DU level granularity. -If the number of UEs offloaded are neither relatively high nor rela-tively low, the source node may select a DU-level granularity. In some embodiments, an operator of a network may configure therange of number of UEs handed over to characterize the offloading plan volume.For example, when there are <10 UE(s), cell-level EC granularity can be requested, when there are 10-100 UE(s), DU-level EC granularity can be requested, when there are >100 UE(s), node level EC granularity can be requested. In some embodiments, a source node may determine a preferred gran-ularity level using available neighbour relationship information. RAN nodes may exchange information about served cells. For example a list of served cells may beprovided. This may be provided in a list of served cells IE (information element).The list of served cell may be provided in a Xn setup request / response procedureof via a RAN node configuration update procedure. Alternatively or additionally , the list of neighbour cell(s) may be con-figured manually or detected automatically through an ANR (Automatic NeighbourRelation) mechanism. In some embodiments, a source node may request two or moregranularities in an increasing (or decreasing) order of priority. For example, thesource node may indicate the granularities in an order. For example, granularity level 1, granularity level 2,…granularity level x, means that the source node is in- terested in the first granularity level. If the first granularity level is not supportedby the target node, then the second granularity level is provided. If the second gran-ularity level is not supported by the target node, then the third granularity level is provided, and so on. Because the source node is interested in any of the requested granular-ity levels, the non-support of a particular granularity level by the target node mightnot result in an error, because the target node may still provide information at an alternative granularity level. Asource node may evaluate the granularity based on one or more trig-gers related to its neighbour node e.g. a new neighbour relation is added eithermanually or through ANR, a served cell is added or deleted and decide if the gran-ularity associated with the energy cost reporting needs to be changed.In some embodiments, the target node may evaluate if the requested ECgranularity can be supported. If a requested granularity is not supported or feasi-ble, the reporting target node can indicate to the requesting source node that re-porting of a different granularity level is possible e.g., by selecting a granularity level that is the next granularity in the priority list of the requested set of granular-ities. This granularity level may be, for example, a granularity level that is coarserthan the requested granularity level. For example, the source node may requestcell-level EC granularity and DU level EC granularity in the priority list, with the celllevel EC granularity having a higher priority than the DU level EC granularity. Inthis example scenario, the cell is sharing physical resources with other cells (re-source pooling scenario). Upon reception of a request for EC reporting, the targetnode determines if different granularities in the list can be supported. The targetnode may start from the granularity with the higher priority, in this example the cell-level EC granularity. When the target node determines that it cannot support this granularity level, the target node may check the next granularity in the list, namely the DU level EC granularity. When the target node determines that this granularity level can be supported, the target node informs the source node that DU-level EC reporting can be supported. The target node may optionally indicate the granularities that are not supported and include a cause value indicating the reason for not supporting the respective granularity. The target node may thus determine support of the different EC granu- larities in the list. If the target node does not support the first indicated granularityin the list (highest priority), the target node tries the second, third, fourth and soon, until all granularities are checked. The reporting node will only report an errorif none of the requested EC granularity levels by the source node is supported. Thiscould be done through a cause value e.g., “EC granularity level(s) not supported”.In some embodiments, a source node is able to request different levels of EC granularity. The different levels may indicate different priorities with which EC measurement from the target node is requested. In some embodiments, the target node may provide the finest possibleor available granularity while reporting an EC measurement. Reference is made to Figure 4 which shows a procedure of some em-bodiments. As referenced 1, the first NG-RAN sends a data collection request to thesecond NG-RAN. This may be an XnAP message.The data collection message may request one or more measurements or predictions from the second NG-RAN node 2. These measurements or predictions may be per cell, per UE, or per- node. Per cell measurements or predictions may comprise one or more of: predicted radio resource status; predicted number of active UEs; or predicted RRC connections. Per UE measurements or predictions may comprise one or more of: av- erage UE throughput DL; average UE throughput UL; average packet delay; average packet loss DL; or measured UE trajectory. The data collection message may comprise information about a preferred granularity of the energy cost. For example, the data collection message may indicate that a preferred granularity is one of a cell level; a DU level; and a node level. The data collection message may comprise a preferred EC granularity priority. This may be provided by an IE. The preferred EC granularity priority maybe an ordered list indicating the order of preferred EC granularity levels requestedto be reported by the target node. As an example, a possible set of values are celllevel, DU level and node level.In some embodiments, the priority may be configured per target cell.As referenced 2, the target node may indicate the accepted EC granular-ity level in a data collection response. The data collection response may be an XnAPmessage. The target node may check the feasibility / availability of different EC granularity levels and may include the EC granularity level that has the highest pri- ority in the request from the source node. For example, for a given target cell, the source node can indicate that itprefers cell-level EC as a first priority, DU-level EC as a second priority and node-level EC as a third priority. The target node may check which measurements arefeasible by it and for example may decide that only DU-level granularity can be sup- ported by it. The target node may provide an indication that DU-Level EC granularitysupported. The target node may indicate in the data collection response messagethat the target node will report the DU-level EC in a subsequent data collection up-date message. Reference is made to Figure 5 which shows the providing of a data col- lection update message from the target node to the source node. The data collectionupdate message may be an XnAP message. The data collection update message mayinclude the energy cost as per the accepted EC granularity level.If the accepted EC granularity level is the node level, the second NG-RAN node 2 may send a single energy cost which is sum of EC of all the components(DU, CU) to NG-RAN node 1.In some embodiments, the second NG-RAN node 2 may include EC ofone or more specific DUs which are impacted by the offloading action i.e.. the oneor more DUs that are serving the one or more target cells. For example, the DUimpacted by the offloading action and having with the highest EC may be reported.This may enable the source node to be aware of the DU that is contributing themaximum for the overall node level EC. In some embodiments, the NG-RAN node 2 may provide individual en-ergy cost for each of the involved DUs. If the accepted EC granularity level is the DU level, the second NG-RANnode 2 may send an individual EC of a specific subset of one or more DU impactedby handover (i.e., the specific set of one or more DUs hosting the one or more targetcells to which one or more UEs are offloaded). The DU Level EC report also maycomprise a DU ID. For example, if the NG-RAN node 2 has 10 DUs and the one ormore UEs are handed over to target cells which are hosted in 2 DUs only, the reportcontains the EC from those specific 2 DUs only.The source node may evaluate the impact of the offloading action moreaccurately by comparing the energy cost from those one or more specific DUs be-fore and after the offloading action. If the accepted EC granularity level is the cell level, the second NG-RAN node 2 may send the individual energy cost of a specific subset of one or more cells impacted by offload.. When the cell level EC is not feasible to be measured due to resourcepooling or other constraints, it may be possible to report a RU-level EC (from thespecific RU serving the cell). The table below shows some examples of requested levels of EC granu- larity and the respective options for accepted EC granularity. Sl.^No Requested^ EC^ Granular-Accepted^EC^Granularity ity 1Priority 1: Node Level Node Level2 Priority 1: DU LevelDU Level or Priority 2: Node Level Node Level3 Priority 1: Cell LevelCell Level or Priority 2: DU Level DU (RU Level) or Priority 3: Node Level DU Level or Node Level Reference is made to Figures 6A and B which shows a another exampleof a procedure of some embodiments. As referenced 0.0, the first NG-RAN node 1 determines a reporting pri-ority for each of the energy cost levels associated with a respective granularity ofan NG-RAN node. This may define a priority order for the EC levels associated with respective different granularities. This reporting priority is referred to as EC gran- ularity priority order in the following. The EC granularity priority order may be configured by an operator ofthe network or may be determined by the first NG-RAN node 1. The first NG-RANnode 1 node may itself determine the EC granularity priority order for its own en-ergy saving operations. As referenced 0.1, the first NG-RAN node offloads one or more UEs tothe second NG-RAN node 2.As referenced 1, the first NG-RAN node 1 initiates the energy cost re-porting from NG-RAN node 2 using the configured EC granularity priority order.The first NG-RAN node 1 sends a data collection request. This data collection re-quest may be as discussed in relation to Figure 4. The EC granularity priority order from highest priority to lowest prior- ity may be: Cell level; DU level; and node level. It should be appreciated that the reporting priority may be in any other suitable order of priority. As referenced 2.0, a determination may be made by the second NG-RANnode 2 if the second NG-RAN node is able to determine EC at the cell level. Support-ing EC at the cell level may not be feasible if hardware resources of the NG-RANnode 2 are shared across cells.If the cell level EC can be determined, then as referenced 2.1, the secondNG-RAN node 2 responds with a data collection response. The data collection re-sponse may be as discussed in relation to Figure 4. In this example, the data collec- tion response may indicate the finest granularity (e.g. cell level EC) that can be re- ported. As referenced 2.2, the second NG-RAN node 2 starts measuring and re-porting the energy cost at the accepted level of granularity, which in this case is celllevel granularity. In case of cell level EC granularity, the second NG-RAN node 2reports to the first NG-RAN node 1 the energy cost for each target cell to which theone or more UEs are offloaded. In some embodiments, if the cell level EC cannot be reported, the NG-RAN node 2 may respond to the data collection request with a cause value whichmay indicate that the requested EC granularity not supported.In some embodiments, where the EC at the cell level is not supported,the second NG-RAN node 2 may determine if the next level of granularity can besupported. In this case, the NG-RAN node 2 may, as referenced 3.0, determine thatthe physical resources of the second NG-RAN node 2 are shared and that DU levelEC reporting is supported. If the DU level EC can be determined, then as referenced 3.1, the secondNG-RAN node 2 responds with a data collection response. The data collection re-sponse may be as discussed in relation to Figure 4. In this example, the data collec- tion response may indicate the finest granularity (e.g. DU level EC) that can be re- ported. Additionally, in some examples, the response may indicate that the report- ing at the cell level is not supported. As referenced 3.2, the second NG-RAN node 2 starts measuring and re-porting the energy cost at the accepted level of granularity, which is this case is thatat the DU level granularity. In case of DU level EC granularity, the second NG-RANnode 2 reports to the first NG-RAN node 1 the energy cost for each target DU towhich the one or more UEs are offloaded. In some embodiments, if the DU level EC cannot be reported, the NG-RAN node 2 may respond to the data collection request with a cause value whichmay indicate that the requested EC granularity (e.g. DU level) is not supported. This may be done in combination with an indication that the cell level of granularity is not supported. In some embodiments, where the EC at the DU level is not supported,the second NG-RAN node 2 may determine if the next level of granularity can besupported. In this case, the NG-RAN node 2 may, as referenced 4.0, determine thatthe physical resources of the second NG-RAN node 2 are shared and that DU levelEC reporting is not supported.If the node level EC can be determined, then as referenced 4.1, the sec-ond NG-RAN node 2 responds with a data collection response. The data collectionresponse may be as discussed in relation to Figure 4. In this example, data collec- tion response may indicate the finest granularity (e.g. node level EC) that can be reported. Additionally, in some examples, the response may indicate that the re-porting at the cell level and DU level are not supported.As referenced 4.2, the second NG-RAN node 2 starts measuring and re-porting the energy cost at the accepted level of granularity, which is this case is that at the node level granularity. In case of node level EC granularity, the second NG-RAN node 2 reports to the first NG-RAN node 1 the energy cost for at the level ofthe second NG-RAN node 2.In some embodiments, if the node level EC cannot be reported, the NG-RAN node 2 may respond to the data collection request with a cause value whichmay indicate that the requested EC granularity (e.g. node level)is not supported. This may be done in combination with an indication that the cell level and DU level of granularity are not supported. The following table shows some examples for DU Level EC reporting be-tween two RAN nodes. In the examples shown, measurements are made before andafter the offload. EC^ Granu- Measurement^ at^Measurement^Measurement^ sent^ to^larityTarget^ Node^ Be- at^ Target^ Node^source^node^by^Target^ fore^ Offloading^ after^ offloading^node^(gNB-CU-CP) Plan^ execution^ plan^ execution^(EC0) (EC1)Node Level EC of all DU(s) EC of all DU(s) Sum of EC of all DU(s),Sum of EC of all DU(s) and EC of specific DU DU Level –EC of all DU(s) EC of all DU(s) Per-DU EC of specificOption #1 DU(s) or sum of EC from impacted DU(s) DU Level –EC of all DU(s) EC of specificPer-DU EC of specific Option #2 DU(s) based on DU(s) or sum of EC from the offloading impacted DU(s) plan DU Level energy cost exchange and corresponding evaluation may use periodic reporting or one-shot reporting. In case of periodic EC reporting, the source radio access node sets up aperiodic data collection reporting before the offloading action. The target radio ac-cess node sets up the EC reporting from all the configured DU(s). Hence, the sourceradio access node receives DU level EC from each of the DUs of the target radioaccess node before the offloading action.The source node may receive DU level EC from all the DU(s) or specificDU(s) to which one or more UEs were offloaded. This reporting which is providedmay depend on the target radio access node implementation. The source radio ac-cess node may determine the difference in energy cost for all DU(s) or specificDU(s). In case of one-shot EC reporting, the source radio access node may trig- ger two one-shot reports. One report is before the execution of the offloading actionand one report is after the execution of the offloading action. For the first one-shotreport, the target radio access node sets up the EC reporting from all the configuredDU(s). For the second one-shot report, the source radio access node may controlthe target radio access node behaviour to set up EC reporting from only the specificDU(s) that hosts the cell(s) to which UE(s) are offloaded. The source radio accessnode may receive the DU level EC from all the DU(s) of target radio access nodebefore the offloading action but may receive only DU level EC from specific DU(s)to which the UEs are offloaded. The source radio access node may determine thedifference in energy cost for specific DU(s) impacted by the offloading plan by con-sidering the list of DU(s) for which EC was reported in second one-shot report withrespect to the corresponding DU EC information received in the first one-shot re- port. Reference is made to Figures 7A and B which shows an example proce-dure illustrating the DU-Level – Option #1 in the table above.In this example, the first NG-RAN node 1 evaluates the difference in en-ergy cost using periodic DU-level EC reporting before and after the offloading ofone or more UEs to the second NG-RAN node 2.Before the offloading of one or more UEs, a periodic DU-level report isreceived from all DU(s) of the second NG-RAN node 2 . This may be received fromthe gNB-CU-CP of the second NG-RAN node 2. The second NG-RAN node 2 (e.g. gNB-CU-CP) sends the energy cost from all DU(s) to the first NG-RAN node 1.After the offloading of one or more UEs, the periodic DU-level report isreceived from all DU(s) at the gNB-CU-CP of the second NG-RAN node 2. The secondNG-RAN node 2 (e.g. gNB-CU-CP) filters and sends only the energy cost for the oneor more DUs which host the one or more target cells to which the one or more UEsare offloaded. In some embodiments, the first NG-RAN node 1 sends a list of one ormore cells in the second NG-RAN node 2 which are configured as neighbours forthe cell(s) in the first NG-RAN node 1. The second NG-RAN node 2 looks up a map-ping table with a list of cells supported by the second NG-RAN node 2 to identifylist of DU(s) serving those cells. The second NG-RAN node 2 may measure and re-port DU-level EC only from these DU(s) which serve those cells.As referenced 1, the first NG-RAN node 1 sends a data collection requestto the second NG-RAN node 2 to initiate energy cost reporting from the second NG-RAN node 2. The data collection request may be as discussed in relation to Figure4. In this example, the EC granularity reporting priority has the DU-level reportingas a first priority and the node level reporting as second lower priority. The requestmay be received by the gNB-CU-CP of the second NG-RAN node 2.As referenced 2, the second NG-RAN node 2 (e.g. the gNB-CU-CP) initi-ates energy Cost reporting from the first DU, DU1. The EC granularity reporting priority may be provided to the first DU, DU1. In some embodiments, the gNB-CU- CP of the second NG-RAN node 2 sends a F1AP data collection request to the first DU, DU1. It should be noted that in this illustrative example, the first DU, DU1 hosts cells 1, 2 and 3. As referenced 2.1, the second NG-RAN node 2 (DU1) checks if the re-quested EC granularity reporting (DU-level) can be accepted. As referenced 3, the second NG-RAN node 2 (DU1) sends a data collec-tion response to the second NG-RAN node 2 (gNB-CU-CP), when the requested ECgranularity reporting (DU-level) can be accepted. As referenced 4, the second NG-RAN node 2 (e.g. the gNB-CU-CP) initi- ates energy cost reporting from the second DU, DU2. The EC granularity reportingpriority may be provided to the second DU, DU2. In some embodiments, the datacollection request is sent by the gNB-CU-CP of the second NG-RAN node 2 to thesecond DU, DU2. It should be noted that in this illustrative example, the second DU, DU2 hosts cells 4, 5 and 6 As referenced 4.1, the second NG-RAN node 2 (DU2) checks if the re- quested EC granularity reporting (DU-level) can be accepted. As referenced 5, the second NG-RAN node 2 (DU2) sends a data collec- tion response to the second NG-RAN node 2 (gNB-CU-CP), when the requested EC granularity reporting (DU-level) can be accepted. As referenced 6, the second NG-RAN node 2 (gNB-CU-CP) sends a datacollection response to the first NG-RAN node 1 (gNB-CU-CP) which confirms thatthe data collection with the first and second DUs is setup successfully. As referenced 7, the NG-RAN node 2 (DU1) starts determining the DU-level energy cost as per the configured reporting configuration. As referenced 8, the NG-RAN node 2 (DU2) starts determining the DU- level energy cost as per the configured reporting configuration.As referenced 9, the NG-RAN node 2 (gNB-CU-CP) reports the DU1 en-ergy cost and DU2 energy cost to the first NG-RAN node 1 (gNB-CU-CP). The NG-RAN node 1 considers this as an initial energy cost EC0 before the one or more UEsare handed over to NG-RAN node 2. (This is referenced 9.1 in Figure 7B).As referenced 10.1 – 10.n, the first NG-RAN node 1 starts offloading theUEs. In this example, the first NG-RAN node triggers a handover preparation pro-cedure for each UE currently served by the first NG-RAN which is to be handed overto the second NG-RAN node. As referenced 10.1, a handover preparation request in respect of cell 2is sent to the second NG-RAN node (gNB-CU-CP). This is propagated to DU1 of thesecond NG-RAN node. As referenced 10.2, a handover preparation request in respect of cell 5is sent to the second NG-RAN node (gNB-CU-CP). This is propagated to DU2 of thesecond NG-RAN node. As referenced 10.3, a handover preparation request in respect of cell 4is sent to the second NG-RAN node (gNB-CU-CP). This is propagated to DU2 of thesecond NG-RAN node. As referenced 10.n, a handover preparation request in respect of cell 1is sent to the second NG-RAN node (gNB-CU-CP). This is propagated to DU1 of thesecond NG-RAN node. As referenced 11, the second NG-RAN node 2 (DU1) starts measuringthe DU-level energy cost as per the configured reporting configuration and pro-vides the EC for DU1 to the second NG-RAN node (gNB-CU-CP).As referenced 12, the second NG-RAN node 2 (DU2) starts measuringthe DU-level energy cost as per the configured reporting configuration and pro-vides the EC for DU2 to the second NG-RAN node (gNB-CU-CP).As referenced 13.0, the second NG-RAN node 2 (gNB-CU-CP) identifiesthe specific one or more DUs based on the one or more target cells to which the oneor more UEs are offloaded and reports only those energy cost measurements forthose specific one or more DUs to the first NG-RAN node 1.As referenced 13, in this example, the NG-RAN node 2 (gNB-CU-CP)reports the DU1 Energy Cost and DU2 Energy Cost to the NG-RAN node 1 (gNB-CU-CP). As referenced 14.0, the first NG-RAN node 1 considers this as the sub-sequent energy cost EC1 after the UE(s) are handed over to NG-RAN node 2.As referenced 14.1, the first NG-RAN node 1 may determine a differencein the energy cost by determining EC1-EC0 (or vice versa).Reference is made to Figures 8A and B which shows an example proce-dure illustrating the DU-Level – Option #2 in the table above.In this example, the first NG-RAN node 1 evaluates the difference in en- ergy cost using one shot DU-level EC reporting before and after the offloading of one or more UEs to the second NG-RAN node 2. Before execution of offloading, a one-shot DU-level report is receivedfrom all DU(s) at the second NG-RAN node 2 (gNB-CU-CP). The second NG-RANnode 2 (gNB-CU-CP) sends the energy cost from all DU(s) to NG-RAN node 1. Thisis shown in the part of the procedure referenced 1 to 9.1, which is generally thesame as the parts of the procedure referenced 1 to 9.1 of Figures 6A and B. It shouldbe noted that the data collection request sent in the part of the procedure refer-enced 1 in Figure 8A is to trigger the one shot report before the offloading of theone or more UEs to the second NG-RAN node 2. After execution of offloading, the NG-RAN node 2 (gNB-CU-CP) config-ures one-shot DU-level EC report from only the one or more specific DUs whichhost one or more target cells to which UE(s) are offloaded. The part of the proce-dure is referenced 10.0 to 19.1. It should be noted that the parts of the procedure referenced 10.1 to 10.n are generally same as the parts of the procedure referenced 10.1 to 10.n ofFigures 6A and B.As reference 11.0, the second NG-RAN node 2 (gNB-CU-CP) identifies the specific one or more DUs based on the one or more target cells to which the one or more UEs are being offloaded. As referenced 11, the first NG-RAN node 1 sends a data collection re- quest to the second NG-RAN node 2 to trigger the one shot report before the offloading of the one or more UEs to the second NG-RAN node 2.. The data collec- tion request may be as discussed in relation to Figure 4. In this example, the EC granularity reporting priority has the DU-level reporting as a first priority and the node level reporting as second lower priority. The part of the procedure referenced 12 to 19.1 generally correspondsto the part of the procedure referenced 2 to 10.0 with the part of the procedure referenced 12 to 19.1 relating to the one shot report for after the one or more UEs have been offloaded to the one or more target cells of the second NG-RAN node 2. In some embodiments, the source node signals to the target node a com-mon granularity preference. The target node applies a common granularity prefer-ence to each cell to involved in offloading. In other embodiments, the source node signals to the target node the granularity preference for each individual cell involved in offloading. A first option to signal this information is provided in the table below. In the example provided below, an information element IE is defined which is for cells to report for energy cost. This will have a list of cell IDs and will include a granularity priority for the each of the cell IDs. If this IE is included, then the energy cost reporting may be either at the cell level granularity or DU-level granularity with the specific set of one or moreDU(s) corresponding to the cells indicated. If this IE is not included, then node levelreporting may be provided, in some embodiments. IE / Group^Name Range IE^ type^ and^Semantics^description reference Cell^ To^ Report^Cell ID list to which the En- List^ for^ Energy^ergy cost reporting applies Cost Cell^ To^ Report^ 1^ ..^Item^for^Energy^ <maxnoofCells- Cost inNG-RAN- node>>>Cell ID Global NG-Indicates an NR Cell Identity. RAN Cell Iden- tity >>Granularity Indicates the granularity Priority priority per-cell. It can be set to either Cell-level or DU- level or Node-level. A second option may be to extend the use of “Cells To Report List for Data Collection” to include an IE for EC granularity priority that applies to cells in-cluded in the “Cell To Report List for Data Collection” IE.For example, if the registration request for data collection IE defined inTS 38.4238.4.13.2 is set to "start" in the data collection request message and thereport characteristics for data collection IE indicates cell-specific information re-porting, then the cell to report list for data collection IE may be included.In some embodiments, there may be a dynamic mapping of offloading plan characteristics to energy cost granularity. For example, an operator of a net- work may configure mapping rules indicating the criteria for mapping the offload- ing plan characteristics to the energy cost granularity priority. This may enable theoperator to indicate one or more attributes of the offloading plan (e.g. number ofUEs, bearer characteristics, number of bearers, QoS (quality of service) character- istics, and / or the like), and / or corresponding thresholds / values which map to a particular granularity of energy cost. In some embodiments, volume of the load being offloaded may be re- lated to the granularity level of the energy cost reporting. In some embodiments, the relationship may be the smaller the load, the finer the granularity and the larger the load, the coarser the granularity. In some embodiments, the first NG-RAN node 1 identifies the conditionsto offload one or more UEs. This may be, for example, where the first NG-RAN node1 determines that one or more of its capacity cells is to be switched off. The firstNG-RAN node 1 may check the characteristics of the one or more UEs that are to beoffloaded to NG-RAN node 2 using the configured mapping rules and derive theenergy cost granularity priority. For example, the mapping rule may be based on the number of UEs tobe offloaded. The table below gives an example of a relationship between the num-ber of UEs to be offloaded and the preferred EC granularity. Number^of^UE(s) Energy^Cost^Granu-larity <10 Cell Level10-100 DU Level>100 Node LevelAs an example, when there are <10 UEs to be offloaded, the first NG-RAN node will determine the Energy Cost Granularity priority order as Cell Level,DU Level and Node Level. It should be appreciated that the number of UE associated with each level of energy cost granularity shown in the table above is by way of example only. In some embodiments, a current EC granularity level may be changed to a different EC granularity level. Whenever there is a need to switch to a differentgranularity level or a different preferred order, the source node may stop the ex-isting data collection context and create a new data collection context. Alterna-tively, the source node may modify the existing data collection context. This may be with the need to stop the existing data collection context. In some embodiments, the communication between the source and tar- get nodes may be via a Xn interface. The communication may be via the XnAP (Xn application protocol). In some embodiments, the communication between the CU and the DU may be via the FI interface. The communication may be via the FIAP (F1 application protocol). In some embodiments, the EC information may be used when monitor- ing performance. For example, the performance of a source node and / or target node may be monitored. In some embodiments, the EC information may be used to monitor the performance of at least a part of a network. In some embodiments, the EC information may be used in AI / ML appli- cations. The EC information may be used in deployment and / or configuration sce- narios. The EC information may be used for AI / ML energy saving applications. In some embodiments, such applications may make use of the finest granularity which is supported. Artificial intelligence (AI) can be broadly defined as getting computersto perform tasks mimicking human brain. Machine learning (ML) is one categoryof AI techniques: computer algorithms able to automatically improve their perfor- mance without explicit programming. AI / ML can help adjust and optimize radio access network (RAN) param- eters and settings using (real-time) monitoring and prediction of network perfor- mance, quality, and demand. Additionally, AI / ML can identify and diagnose degra- dation in network performance, as well as provide protection from cyberattacks. AI / ML is usable in energy saving, load balancing, mobility optimization, link adap- tation and security just to mention but a few. It is envisioned that AI / ML will enable real-time analysis as well as au- tomated operation and control in 5G and beyond RAN. This requires the availability of data streamed from wireless devices in a timely manner, especially in extremely time-critical applications such as real-time video monitoring and extended reality (XR). This may be reflected in network architecture, such as by placing and moving ML agents to the required locations in the network, for example for data collection. User devices (mobile devices) may assist network in decision-making in resource management, thus a user device may act as an infrastructure resource. As the network evolves to programmable and flexible cloud native im- plementation, AI / ML-based network automation will be used to simplify network management and optimization. It is expected that parts of the air interface, in par- ticular signal processing algorithms, are supported and eventually even replaced with machine learning models. Thus, a 6G wireless communication standard will natively support an AI-based air interface. Machine learning algorithms are usually classified into four different types: supervised learning, unsupervised learning, semi-supervised learning and reinforcement learning. In supervised learning the algorithm learns from labelled data. For training, the algorithm receives input data and corresponding correct output la- bels. The algorithm is trained to predict accurate labels for new data. In unsupervised learning the algorithm analyses unlabelled data. The aim is to discover patterns, relationships, or structures within the data, for exam- ple, unsupervised learning algorithms make groups of similar data points. Semi-supervised learning is a hybrid machine learning approach that combines labelled and unlabelled data for training. A limited amount of labelled data and a larger set of unlabelled data is used to improve training. This approach is useful when acquiring labelled data is expensive or time-consuming as is the case in many real-world applications. Semi-supervised learning techniques can be ap- plied to various tasks, such as classification, regression, and anomaly detection, al- lowing models to make more accurate predictions and generalize better in real- world scenarios. Reinforcement learning is a machine learning algorithm which learns from trial and error. An ML agent interacts with environment and learns from ex- perience aiming to maximize cumulative rewards. The ML agent receives feedback through rewards or penalties based on its actions. The agent learns to take actions that lead to the most favourable outcomes over time. The algorithm adapts to changing environments, and achieve long-term goals through a sequence of ac- tions. An example of an ML algorithm found applicable to adjust and optimize the radio access network (RAN) parameters and settings is deep learning. Deep learning is a subset of machine learning algorithms using a neural network. Neural networks are also known as artificial neural networks (ANNs) or simulated neural networks (SNNs). Deep learning can be based on supervised, semi-supervised or unsupervised learning. Artificial neural networks (ANNs) are comprised of an input layer, one or more hidden layers, and an output layer. Each node of a layer, or an artificial neuron, connects to another one and has an associated weight as well as a thresh- old value. If the output of an individual node is above the threshold value specified to this node, the node is activated and sending or passing data to the next layer of the neural network. In the case the supervised learning is applied in the training of a neural network, the training is carried out by using examples, each of which contains a known "input" and "result", forming probability-weighted associations between them. The training comprises determining the difference between the output of the neural network (a prediction) for an input and a target output for the same input. The difference is called an error value. The neural network then adjusts its weighted associations according to a learning rule and using this error value. Suc- cessive adjustments makes the neural network produce output that is approaching the target output. After a sufficient number of these adjustments, the training can be terminated based on a certain criteria. The data collection of some embodiments may be used for the collectionof training data. The data collection of some embodiments may be used for the col-lection of data used for inference. Reference is made to FIGs.9 to 13 which show first to fifth methods ofsome example embodiments. Each of the methods may be performed by an apparatus. The apparatusmay comprise or be a radio access node. The access node may be a base station, forexample a gNB. The apparatus may comprise suitable means, such as circuitry for providing the method. Alternatively or additionally, the apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by theat least one processor cause the apparatus at least to provide the method below.Alternatively or additionally, the apparatus may be as discussed in re- lation to FIG.14.Each method may be provided by computer program code or computerexecutable instructions. Each method may be modified to include one or more of the previously described options. Referring to the first method of Figure 9: The method comprises as referenced A1, sending to a second radio ac- cess node, a first request for information on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access node associated with one or more offloading actions. The method comprises as referenced A2, receiving, from the second ra- dio access node, one or more messages providing the requested information on the energy cost at one or more of the plurality of different energy cost levels. Referring to the second method of Figure 10: The method comprises as referenced B1, receiving from a first radio ac- cess node, a first request for information on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access nodeassociated with one or more offloading actions.The method comprises as referenced B2, sending to the first radio ac- cess node one or more messages comprising information on the energy cost asso- ciated with one or more of the one or more offloading actions. Referring to the third method of Figure 11: The method comprises as referenced C1, sending to a second radio ac- cess node a first request comprising information about a plurality of different en- ergy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of the second radio access node, the first request fur- ther comprising a request for information on an energy cost at one or more of the different energy cost levels. The method comprises as referenced C2, receiving, from the second ra-dio access node, one or more messages providing the requested information on the energy cost at one or more of the plurality of different energy cost levels. Referring to the fourth method of Figure 12: The method comprises as referenced D1, receiving from a first radio ac- cess node a first request comprising information about a plurality of different en- ergy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of the second radio access node, the first request fur- ther comprising a request for information on an energy cost at one or more of the different energy cost levels. The method comprises as referenced D2, sending to the first radio ac- cess node, one or more messages providing the requested information on the en- ergy cost at one or more of the plurality of different energy cost levels. Referring to the fifth method of Figure 13:The method comprises as referenced E1, selecting one or more of a plu- rality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of a second radio access node, the selecting being based on one or more characteristics of one or more user equip- ment to be offloaded from the first radio access node to the second radio access node. The method comprises as referenced E2, sending to the second radio access node a first request for information of an energy cost associated with the offloading of the one or more user equipment from the first radio access node to the second radio access node, the energy cost being one or more of the selected oneor more of the plurality of different energy cost levels.The method comprises as referenced E3, receiving, from the second ra- dio access node, one or more messages providing the requested information on the energy cost at one or more of the selected one or more of the plurality of different energy cost levels. Fig.14 shows, by way of example, a block diagram of an apparatus 10. The apparatus 10 comprises, for example, at least one processor 12 and at least onememory 14 storing instructions 15 that, when executed by the at least one proces-sor, cause the apparatus 10 at least to perform the method or methods as disclosedherein, and any of the embodiments thereof. In an example, the at least one memory and the instructions (e.g. a computer program code, software), areconfigured, with the at least one processor, to cause the apparatus 10 to performthe method or methods as disclosed herein, and any of the embodiments thereof. A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of meth- ods in accordance with example embodiments described herein. As used in this ap- plication, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and / or digital hardware cir- cuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a mi- croprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term in this ap- plication, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or net- work device. The memory 14 may be implemented using any suitable data storagetechnology. The memory may comprise a database for storing data. The memory14 may be at least in part external to apparatus 10 but accessible to apparatus 10. The instructions 15 may be comprised in a computer readable medium or a non-transitory computer readable medium. A term non-transitory, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. random access memory, RAM, vs. read only memory, ROM). As an example, the apparatus 10 is a radio access node such as previ-ously described. In another embodiment, the apparatus is comprised in such a ra- dio access node, e.g. as a chipset configured to control the radio node. The appa-ratus 10 may be caused or configured to perform any of the methods of Figs. 9 to13 and / or any one or more of the embodiments described. The apparatus may comprise one or more entities of any of protocol lay- ers, such as a MAC entity, an RRC entity, an RLC entity, a PDCP entity or a PHY en- tity. The apparatus 10 comprises a radio interface 16. The radio interface 16may provide the apparatus 10 with communication capabilities. The radio inter-face 16 may comprise a receiver configured to receive information in accordancewith at least one cellular or non-cellular standard. The radio interface 16 may com- prise a transmitter configured to transmit information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio in-terface 16 may comprise a transceiver configured to receive and transmit infor-mation in accordance with at least one cellular or non-cellular standard. The trans-ceiver may comprise more than one transceiver. In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 10. For ex- ample, the at least one processor 12, the memory 14, and the computer program code form means for carrying out the method or methods as disclosed herein, andany of the embodiments thereof. As used herein the term “means” is to be con-strued in singular form, i.e. referring to a single element, or in plural form, i.e. re- ferring to a combination of single elements. Therefore, terminology “means for[performing A, B, C]”, is to be interpreted to cover an apparatus in which there isonly one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for per- forming A, B and C, or partially or fully overlapping means for performing A, B, C. Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be com- bined with other embodiments in various ways.

Claims

CLAIMS 1. A first radio access node comprising:means for sending to a second radio access node, a first request for in- formation on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access node associated with one or more of-floading actions; andmeans for receiving from the second radio node one or more messages comprising information on the energy cost associated with one or more of the one or more offloading actions.

2. The first radio access node as claimed in claim 1, whereinthe first request comprises information about a plurality of different energy cost levels including an energy cost associated the one or more distributed units of thesecond access node, each of the plurality of different energy cost levels being asso-ciated with a different granularity of the second radio access node.

3. The first radio access node as claimed in claim 2, whereinthe plurality of different energy cost levels further comprises one or more of an energy cost level at a node level of the second radio access node or at a level of one or more cells of the second radio access node.

4. The first radio access node as claimed in claim 2 or 3,wherein each of the different energy cost levels is associated with a reporting pri- ority.

5. The first radio access node as claimed in any one ofclaims 2 to 4, wherein the first request further comprises a request for information on an energy cost at two or more of the different energy cost levels including the energy cost of the one or more distributed units.

6. The first radio access node as claimed in any of claims 2to 5, wherein one or more messages further comprise information on the energy cost at one or more of the plurality different energy cost levels in addition to the energy costs of the one or more distributed units.

7. The first radio access node as claimed in 6, wherein theone or more messages comprise an indication as to the respective energy cost level associated with the information on the respective energy cost.

8. The first radio access node as claimed in any precedingclaim, wherein the first request comprises configuration information relating to re- porting of the energy cost of the one or more distributed units.

9. The first radio access node as claimed in claim 8, whereinthe configuration information relating to the reporting of the energy cost indicates one of: reporting of the energy cost periodically; or one time reporting of the en- ergy cost.

10. The first radio access node as claimed in any precedingclaim, wherein the first request comprises a request for data collection.

11. The first radio access node as claimed in any precedingclaim, wherein the one or more messages comprises one or more of: a data collec- tion response; or a data collection update message.

12. The first radio access node as claimed in claim 10 or 11,wherein the data collection comprises data collection for one or more machine learning models.

13. The first radio access node as claimed in any precedingclaim, wherein one or more of the first request or the one or more messages are exchanged via an Xn interface between the first radio access node and the secondradio access node.

14. The first radio access node as claimed in any precedingclaim, wherein one or more of the first radio access node or the second radio access node comprise a next generation radio access node.

15. The first radio access node as claimed in any precedingclaim, wherein one or more of the one or more messages comprise information about the respective energy cost of two or more of the distributed units.

16. The first radio access node as claimed in any one ofclaims 1 to 14, wherein one or more of the one or more messages comprise summed information about the energy cost of two or more of the distributed units.

17. The first radio access node as claimed in any precedingclaim, comprising means for receiving from the second radio access node, prior to the one or more offloading actions, information reporting an initial energy cost as- sociated with all distributed units of the second radio access node.

18. The first radio access node as claimed in claim 17, com- prising means for determining an effect of one or more of the one or more offload-ing actions using the information reporting the initial energy cost and the infor-mation on the energy cost associated with one or more of the one or more offload- ing actions.

19. The first radio access node as claimed in any precedingclaim, wherein the first request comprises a list of one or more cells of the secondradio access node.

20. A second radio access node comprising:means for receiving from a first radio access node, a first request forinformation on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access node associated with one or more of-floading; andmeans for sending to the first radio access node one or more messages comprising information on the energy cost associated with one or more of the one or more offloading actions.

21. The second radio access node as claimed in claim 20,comprising a centralized unit, said centralized unit comprising means for collectinginformation about the energy cost of the one or more distributed units from the one or more distributed units.

22. The second radio access node as claimed in claim 20,wherein the first request comprises a list of one or more cells of the second radioaccess node and the second radio access node comprising a centralized unit for de- termining the one or more distributed units based on the list of one or more cells of the second radio access node.

23. The second radio access node as claimed in claim 21 or22, wherein the centralized unit and the one or more distributed units are config-ured to communicate via an F1 interface.

24. A method comprising:sending to a second radio access node, a first request for information on an energy cost, the energy cost being the energy cost of one or more distributed units of the second radio access node associated with one or more offloading ac-tions; andreceiving from the second radio access node one or more messages comprising information on the energy cost associated with one or more of the one or more offloading actions.

25. A method comprising:receiving from a first radio access node, a first request for information on an energy cost, the energy cost being the energy cost of one or more distributedunits of the second radio access node associated with one or more offloading ac-tions; andsending to the first radio access node one or more messages comprising information on the energy cost associated with one or more of the one or more offloading actions.

26. A first radio access node comprising:means for sending to a second radio access node a first request com- prising information about a plurality of different energy cost levels, each of the plu- rality of different energy cost levels being associated with a different granularity of the second radio access node, the first request further comprising a request for in- formation on an energy cost at one or more of the different energy cost levels; and means for receiving, from the second radio access node, one or more messages providing the requested information on the energy cost at one or more of the plurality of different energy cost levels.

27. The first radio access node as claimed in claim 26,wherein each of the different energy cost levels is associated with a reporting pri- ority.

28. The first radio access node as claimed in claim 27,wherein the one or more messages providing the requested information on the en- ergy cost provides the requested information on one or more of the different en- ergy cost levels having a highest reporting priority and the reporting of which is supported by the second radio access node.

29. The first radio access node as claimed in any of claims 26to 28, wherein the plurality of different energy cost levels comprise one or more of:an energy cost level at a node level of the second radio access node; at a level of one or more cells of the second radio access node; or at a level of one or more distrib- uted units of the second radio access node.

30. The first radio access node as claimed in any of claims 26to 29, wherein one or more of the one or more messages comprise information about the respective energy cost at two or more of the plurality of different energy cost levels.

31. The first radio access node as claimed in claim 30, wherein the respective energy cost at one of the two or more levels is defined with respect to the respective energy cost at another of the two or more levels.

32. A second radio access node comprising:means for receiving from a first radio access node a first request com- prising information about a plurality of different energy cost levels, each of the plu- rality of different energy cost levels being associated with a different granularity of the second radio access node, the first request further comprising a request for in- formation on an energy cost at one or more of the different energy cost levels; and means for sending to the first radio access node, one or more messages providing the requested information on the energy cost at one or more of the plu- rality of different energy cost levels.

33. The second access node as claimed in claim 32, compris-ing: means for receiving from a third radio access node a second request comprising a request for information on an energy cost at one or more of the dif- ferent energy cost levels; and means for sending to the third radio access node, one or more messages providing the requested information on the energy cost at one or more of theplurality of different energy cost levels, one or more of which is at different energy cost level different to the information provided to the first access node.

34. A method comprising:sending to a second radio access node a first request comprising infor- mation about a plurality of different energy cost levels, each of the plurality of dif- ferent energy cost levels being associated with a different granularity of the second radio access node, the first request further comprising a request for information on an energy cost at one or more of the different energy cost levels; and receiving, from the second radio access node, one or more messages providing the requested information on the energy cost at one or more of the plu- rality of different energy cost levels.

35. A method comprising:receiving from a first radio access node a first request comprising infor- mation about a plurality of different energy cost levels, each of the plurality of dif- ferent energy cost levels being associated with a different granularity of the second radio access node, the first request further comprising a request for information on an energy cost at one or more of the different energy cost levels; and sending to the first radio access node, one or more messages providing the requested information on the energy cost at one or more of the plurality of dif- ferent energy cost levels.

36. A first radio access node comprising:means for selecting one or more of a plurality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of a second radio access node, the selecting being based on one or more characteristics of one or more user equipment to be offloaded fromthe first radio access node to the second radio access node;means for sending to the second radio access node a first request for information of an energy cost associated with the offloading of the one or moreuser equipment from the first radio access node to the second radio access node, the energy cost being one or more of the selected one or more of the plurality of different energy cost levels; and means for receiving, from the second radio access node, one or more messages providing the requested information on the energy cost at one or more of the selected one or more of the plurality of different energy cost levels 37. A method comprising:selecting one or more of a plurality of different energy cost levels, each of the plurality of different energy cost levels being associated with a different granularity of a second radio access node, the selecting being based on one or more characteristics of one or more user equipment to be offloaded from the first radio access node to the second radio access node; sending to the second radio access node a first request for information of an energy cost associated with the offloading of the one or more user equipment from the first radio access node to the second radio access node, the energy costbeing one or more of the selected one or more of the plurality of different energycost levels; and receiving, from the second radio access node, one or more messages providing the requested information on the energy cost at one or more of the se- lected one or more of the plurality of different energy cost levels.

38. A computer program comprising computer executable in-structions which when executed by at least one processor provide the method ofany one of claims 24, 25, 34, 35, or 37.

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