Methods and apparatus for supporting establishment of an association between a UE and a cell

Abstract

Methods (100, 200) are disclosed for supporting establishment of an association between a UE and a cell in a communication network. The methods include, at a second node, providing (202) a request for candidate cells for a UE to a first node. The methods further include, at the first node, determining (104) one or more candidate cells for the UE from a plurality of cells, based on a first input indicating a Key Performance Indicator, KPI, requirement of the UE and a second input indicating energy saving configurations of the plurality of cells, and providing (106) the determined candidate cells to the second node. The methods further include, at the second node, initiating (206) establishment of an association between the UE and one of the one or more provided candidate cells.

Description

[0001] Methods and apparatus for supporting establishment of an association between a UE and a cell

[0002] Technical Field

[0003] The present disclosure relates to methods for supporting establishment of an association between a user equipment, UE, and a cell in a communication network. The methods may be performed by a first node and a second node in a communication network. The present disclosure also relates to a first node and a second node configured to support establishment of an association between a UE and a cell.

[0004] In wireless communication networks, a base station serves as a connection point for UEs. When a UE connects to the network a base station suitable to serve the UE is selected and an association between the UE and the selected base station is established, or more specifically between the UE and a cell of the selected base station. In various network deployment scenarios, there may be multiple base stations, each with one or more cells, which could serve the UE. Examples include dense network deployments in an enterprise or a campus area, or distributed Multiple Input Multiple Output (MIMO) use cases where Transmission Reception Points (TRPs) can be deployed in abundance.

[0005] The selection of a serving cell from multiple cells covering an area where the UE is located is often based on Received Signal Strength Indication (RSSI) and the cell associated with the highest RSSI is selected to serve the UE. The UE to cell association is kept until, for example, a cell with a higher RSSI is found or the performance toward the serving cell drops significantly. In addition to RSSI, load in the cells can be considered during the selection of serving cell to achieve load balancing, i.e., to avoid having some cells overloaded while others being underloaded.

[0006] However, there are also other factors which may affect which cell is most suitable to serve a UE. Basing the selection of a serving cell for a UE only on signal strength and load may hence not be optimal and may negatively affect both the UE and the network.

[0007] It is an aim of the present disclosure to provide methods, a first node and a second node which at least partially address one or more of the challenges mentioned above. It is a further aim of the present disclosure to provide methods, a first node and a second node which improves the UE to cell association such that KPI requirements of the UE can be met while minimizing the energy consumption in the network.

[0008] According to one aspect of the present disclosure, there is provided a computer implemented method for supporting establishment of an association between a UE and a cell. The method, performed by a first node, comprises obtaining a request for candidate cells for a user equipment, UE, from a second node. The candidate cells are candidates for the UE to be associated with. The method further comprises determining one or more candidate cells for the UE from a plurality of cells, based on a first input indicating a Key Performance Indicator, KPI, requirement of the UE and a second input indicating energy saving configurations of the plurality of cells. A cell is determined to be a candidate cell if the cell fulfills the KPI requirement of the UE and an energy saving condition associated with the energy saving configuration of the cell. The method further comprises providing a response indicating the determined one or more candidate cells to the second node.

[0009] According to another aspect of the present disclosure, there is provided a computer implemented method for supporting establishment of an association between a UE and a cell. The method, performed by a second node, comprises providing a request for candidate cells for a UE to a first node. The candidate cells are candidates for the UE to be associated with. The method further comprises obtaining a response indicating one or more candidate cells for the UE from the first node, each candidate cell fulfilling a KPI requirement of the UE and an energy saving condition associated with an energy saving configuration of the candidate cell. The method further comprises initiating establishment of an association between the UE and one of the one or more candidate cells.

[0010] According to another aspect of the present disclosure, there is provided a first node for supporting establishment of an association between a UE and a cell. The first node comprising processing circuitry configured to cause the first node to obtain a request for candidate cells for a UE from a second node. The candidate cells are candidates for the UE to be associated with. The processing circuitry further configured to cause the first node to determine one or more candidate cells for the UE from a plurality of cells based on a first input indicating a KPI requirement of the UE and a second input indicating energy saving configurations of the plurality of cells. A cell is determined to be a candidate cells if the cell fulfills the KPI requirement of the UE and an energy saving condition associated with the energy saving configuration of the candidate cell. The processing circuitry further configured to cause the first node to provide a response indicating the determined one or more candidate cells to the second node.

[0011] According to another aspect of the present disclosure, there is provided a second node for supporting establishment of an association between a UE and a cell. The second node comprising processing circuitry configured to cause the second node to provide a request for candidate cells for a UE to a first node. The candidate cells are candidates for the UE to be associated with. The processing circuitry further configured to cause the second node to obtain a response indicating one or more candidate cells for the UE from the first node, each candidate cell fulfilling a KPI requirement of the UE and an energy saving condition associated with an energy saving configuration of the candidate cell. The processing circuitry further configured to cause the second node to initiate establishment of an association between the UE and one of the one or more candidate cells.

[0012] Aspects of the present disclosure provide methods and nodes that can improve the association process for a UE by finding cells which are suitable to serve the UE without negatively impacting energy savings in the cells. By considering KPI requirements and energy saving configurations reflecting energy saving mechanisms in the served UEs and the cells, the cell selection process can be improved such that new UE to cell associations do not negatively impact either the UE service or possible energy savings in the network. Thereby, providing a good user experience while minimizing energy consumption in the network.

[0013] One advantage of the UE to cell association according to the invention is hence that the overall energy consumption among the plurality of cells can be minimized.

[0014] Another advantage is that it can be ensured that the UE can get a requested Quality-of- Service (QoS) at an initial association or a re-association, thereby providing a good user experience.

[0015] Brief Description of the Drawings

[0016] For a better understanding of the present disclosure, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the following drawings in which: Figure 1 is a flow chart illustrating process steps in a computer implemented method for supporting establishment of an association between a UE and a cell;

[0017] Figure 2 shows input to and output from the first node;

[0018] Figure 3 is a flow chart illustrating process steps in another computer implemented method for supporting establishment of an association between a UE and a cell;

[0019] Figure 4 shows an example network deployment scenario;

[0020] Figure 5 is a block diagram illustrating functional modules in an example first node;

[0021] Figure 6 is a block diagram illustrating functional modules in an example second node; and

[0022] Figure 7 is a block diagram illustrating functional components in a system for supporting establishment of an association between a UE and a cell.

[0023] Detailed

[0024] Several energy saving mechanisms have been introduced for wireless communication networks to decrease energy consumption in the network. For example, the Discontinuous Reception (DRX) mechanism for UEs and sleeping modes for base stations.

[0025] The DRX mechanism is designed to reduce the energy consumption of UEs by strategically controlling periods during which the UE radio is active and inactive. The DRX cycle begins or is triggered at a specified offset, prompting the UE to awaken for monitoring some control channels during an ON period. When the ON period timer expires, the UE transitions into a dormancy phase. In the dormancy phase, the UE radio is at least partly inactive, i.e., the dormancy phase may correspond to a sleep phase / mode. Notably, the dormancy phase involves significantly lower energy consumption for the radio components of the UE, contributing to overall energy efficiency. If the UE receives data during an ON period, it incurs additional energy consumption. Following the data reception phase, the UE resets an inactivity_period timer and enters the dormancy phase again upon its expiration. Sleeping in base stations is a widely employed strategy to reduce energy consumption of the Radio Access Network (RAN). Base stations can temporarily deactivate certain radio hardware components such as power amplifiers or even the entire radio frequency chain to save energy. Depending on the number and type of deactivated components, we might have different sleeping modes which can be characterized by their energy conservation, the latency required to reactivate the hardware components, as well as a ramp-down / ramp-up energy. 3GPP provides details of various base station sleeping modes for New Radio (NR), see Tables 5.1-3, 5.1-4, and 5.1-5 in 3GPP TR 38.864. These tables illustrate a fundamental trade-off inherent in sleeping functionality. The greater the depth of the sleeping mode, the less energy will be consumed by the RAN. However, this comes at the expense of an increased delay in switching back on, potentially leading to additional latency for UEs.

[0026] A critical aspect of the base station sleeping is the great impact of the deep_sleep mode, where the entire radio chain of the base station is turned off, resulting in substantial energy savings. The existing base station sleeping studies take incoming cell traffic as an input and employ various models, including Machine Learning (ML) models, to predict near-future traffic and apply suitable sleeping strategies. However, when incoming traffic is random and uncontrollable, opportunities for sleeping, especially deep_sleep, become scarce. Introducing DRX into this design loop enables the base station to shape cell traffic and create conditions favourable for deeper sleeping modes.

[0027] Another variation of base station sleeping is known as Multiple Input Multiple Output (MIMO) sleeping, where a subset of antennas enters sleeping modes while the remaining antennas remain active. This strategy involves turning off a portion of the antenna ports, leading to increased energy savings. However, this comes at the cost of reduced cell capacity, potentially resulting in higher delays for connected UEs.

[0028] The existing solutions for selecting a serving cell for a UE are unaware of e.g., the UE service type and energy saving status of the base station serving the cell. The base station can improve energy saving for some UE service types like enhanced Mobile Broadband (eMBB) by optimally configuring DRX for the UE, but much less so for other UE service types with strict delay requirements like Ultra Reliable Low Latency Communications (URLLC) or video-on-demand traffics. Thus, associating a UE running a service with strict delay requirements to a cell of a base station which currently enjoys good energy saving opportunities can substantially stress the energy saving scheduler of the base station.

[0029] Examples of the present disclosure propose methods and nodes for supporting establishment of an association between a UE and a cell. The proposed methods and nodes address the above discussed problems of not considering the service requirements of the UE and energy saving aspects of the base station when association a UE with a cell. In this manner, examples of the present disclosure enable association between a UE and a cell which can jointly optimizes the service requirements of the UE and the energy saving possibilities of the base station serving the cell. The service requirements may be indicated with KPI requirements of the UE.

[0030] Figure 1 is a flow chart illustrating process steps in a computer implemented method 100 for supporting establishment of an association between a UE and a cell. The method 100 is performed by a first node in a communication network such as e.g., a wireless communication network. The first node may be, or be comprised, in a network access node such as e.g., an access node or management node in a RAN.

[0031] Referring to Figure 1 , the method 100 comprises, in a first step 102, obtaining a request for candidate cells for a user equipment, UE, from a second node. A candidate cell can herein be understood to mean a cell which is a candidate for the UE to be associated with, i.e., a cell which is suitable to serve the UE. In examples, the request may be a control message or indication received by the first node from the second node via an external interface or internal interface between the first node and the second node.

[0032] The method 100 then comprises determining, in step 104, one or more candidate cells for the UE from a plurality of cells based on a first input indicating a KPI requirement of the UE and a second input indicating energy saving configurations of the plurality of cells. A cell is determined to be a candidate cell if the cell fulfills the KPI requirement of the UE and an energy saving condition associated with the energy saving configuration of the cell. In other words, a cell from the plurality of cells is determined to be a candidate cell if it is suitable to serve the UE considering both the KPI requirements of the UE and the energy saving condition of the cell. The plurality of cells may be coverage and / or capacity cells controlled by one or more network access nodes in a geographical area, as will be further discussed with reference to Figure 4. In examples, one or more of the plurality of cells may be served / controlled by the first node and / or the second node.

[0033] A KPI requirement of a UE may be associated with a requested or desired QoS and depend on service or traffic of the UE and / or the UE itself. The KPI requirement may be related to e.g., delay, throughput etc. required to fulfil a QoS.

[0034] An energy saving configuration of a cell may indicate one or more of a Discontinuous Reception (DRX) configuration of the cell, a Discontinuous Reception (DTX) configuration of the cell and a DRX configuration for a UE served by the cell. A cell from the plurality of cells may be associated with one mor more energy saving configurations. For example, one and the same cell may be associated with one or more DRX configurations for UEs, i.e., UE DRX configurations, each UE DRX configuration being used by one or more UEs served by the cell. The energy saving configurations of the cell may indicate the energy saving mechanisms active in the cell.

[0035] An energy saving condition associated with the energy saving configuration of the cell may be a condition related to energy savings in the cell made possible by the energy saving configuration. The energy saving condition may e.g., be a condition to maintain energy savings in the cell or limit a decrease in energy savings, i.e., to minimize the energy saving impact of a new association. This may include an objective to maintain / keep one or more energy saving configurations in the cell, e.g., to continue to support a current energy saving configuration or to enable support of a desired energy saving configuration. The objective may be achieved by not associating a UE to a cell which hinders the cell to support the current / desired energy saving configurations or where the requirements of the UE cannot be fulfilled by the cell due to the energy saving configurations of the cell. In examples, the energy savings may be indicated with an energy saving level, e.g., an average energy saving level that is a result of one or more energy saving modes being activated at different times as defined by the energy saving configurations. Thus, the energy saving condition may be a condition related to an energy saving level resulting from the energy saving configurations of the cell. The energy saving condition may e.g., be to maintain the energy saving level in the cell or keep the energy saving level within an interval such that a current energy saving level in the cell does not decrease with more than a threshold value. The energy saving condition may hence be a condition that an association with the UE should not lead to any, or at least a limited, increase in energy consumption of the cell. The method 100 then comprises providing, in step 106, a response indicating the determined one or more candidate cells to the second node 600. Similar to the request, the response may be a control message or indication sent by the first node to the second node via an external interface or internal interface between the first node and the second node.

[0036] Referring to step 104 in Figure 1 , the determining may comprise evaluating the first input and the second input and based on the result of the evaluation determine, i.e., select, from the plurality of cells one or more candidate cells suitable to serve the UE. The one or more candidate cells are hence the output of the determination. The evaluation of the first input and second input may comprise comparing the KPI requirement of the UE with the energy saving configurations of the plurality of cells to find cells which are able to support the KPI requirement of the UE without negatively impacting energy savings in the cell or at least minimizing the energy saving impact. Thus, depending on the cells capability of supporting the KPI requirements and how an association between the UE and the cell would affects energy savings in the cell, the cell is determined to be a candidate cell or not. For example, the cell may be determined to not be a candidate cell, if the cell has an active Cell DTX / DRX configuration which would not fulfil the delay requirements of the UE. In another example, the UE may not support Cell DTX / DRX and any cell with an active Cell DTX / DRX configuration would hence not be suitable to serve the UE as this would mean that the cell had to stop using Cell DTX / DRX resulting in a big increase in energy consumption. Other factors related to energy saving configurations such period / periodicity of common signals / channels like Synchronization Signal Block (SSB), paging, Physical Random Access Channel (PRACH) etc. may further be used to determine whether the cell is suitable to serve the UE or not.

[0037] In examples, to fulfil the KPI requirement of the UE may be a higher priority objective, while minimizing the energy saving impact on the cell may be a lower priority objective. Thus, the determination may select cells which can fulfil the KPI requirement of the UE and from this subset of cells select the cells where serving the UE would have the least impact on energy saving opportunities in the cell.

[0038] If none of the plurality of cells are able to fulfil the KPI requirements of the UE, the cell closest to being able to fulfil the KPI requirements of the UE may be selected and provided in the response to the second node. Alternatively, an intent management function (IMF) or similar may be engaged to recommend a cell from the plurality of cells.

[0039] In examples, the candidate cells determined in step 104 may be ranked based on energy saving impact and the response provided in step 106 may further indicate the ranking of the one or more candidate cells. The outcome of the determination in step 104 may e.g., be an ordered list of candidate cells, where the first candidate cell in the list has the highest rank. In this case, the response provided in step 106 may provide the candidate cells in an ordered list. The energy saving impact can be understood to mean the impact on energy savings in the cell, if the cell would serve the UE. In other words, how an association between the UE and the cell would affect energy savings in the cell, i.e., the possibility to reduce energy consumption in the cell. A high impact may mean that if the cell would serve the UE, the energy savings in the cell are reduced and the cell would consume more energy, e.g., due to fewer or less deep sleep opportunities in the cell. A low impact may mean that the energy savings in the cell are reduced but less so then for high impact, and no impact may mean that an association between the UE and the cell would have no negative affect on energy savings in the cell. Candidate cells where the energy saving impact of serving the UE is low would have a higher ranking then candidate cells where the energy saving impact on the cell if serving the UE is high.

[0040] As illustrated at step 104a, the determining may further comprise determine for cells of the one or more candidate cell a DRX configuration for the UE. In this case, the response provided in step 106 may further indicate the one or more determined DRX configurations. Thus, one or more DRX configurations may be determined in step 104a, each DRX configuration being associated with one of the one or more candidate cells. The DRX configurations may be initial DRX configurations to be used by the UE once associated with a cell. The determining of the one or more DRX configurations in step 104a may be based on the first input and the second input. Similar to the candidate cells, a DRX configuration may be determined to fulfil the KPI requirements of the UE and promote energy savings in the cell. The DRX configuration may e.g., be a DRX configuration used by one or more UEs already served by the cell.

[0041] In examples, the determining in step 104 and / or 104a is performed using a ML model. The ML model may be a neural network, a multi-armed bandit, a reinforcement learning model or another recommendation system model. As an example, a reinforcement learning or multi armed bandit model may be used that returns suggestion of candidate cells, where the reward may be to maintain current total network energy savings among the plurality of cells, while meeting KPI requirements of existing UEs and the UE for which candidate cells have been requested. Another non-limiting example is to use a deep neural network in which the number of outputs neurons could be equivalent to the number of cells. In this case, the output of the last softmax layer for each output neuron provides the score for corresponding cell to be selected as a candidate for association. Thus, a sorted list of the scores can be seen as the recommendation for the candidate cells. This neural network can be trained using an objective function that is similar to the reward defined in the aforementioned reinforcement learning example.

[0042] For the purposes of the present disclosure, the term “ML model” encompasses within its scope the following concepts: machine Learning algorithms, comprising processes or instructions through which data may be used in a training process to generate a model artefact for performing a given task, or for representing a real-world process or system; and the model artefact that is created by such a training process, and which comprises the computational architecture that performs the task.

[0043] The invention is not limited to using ML models for determining candidate cells, other rule or algorithm based solutions capable of evaluating the input and providing a recommendation of candidate cells based on the input may also be used. The determination may e.g., be performed using a conventional optimization framework that takes computational models of energy consumption as a function of decision variables, as well as the corresponding constraint functions describing the problem and limitations into account. Examples of constraint functions may be a) each UE should be associated to one cell, b) the total number of UEs per cell should not exceed a threshold, etc. A solution algorithm can then be used such as gradient-based (e.g., stochastic gradient descent) or gradient-free (e.g., genetic algorithms, particle swarm methods, approximated simplex methods) algorithms to determine candidate cells.

[0044] Further details related to the input to the determination in the first node will now be described with reference to Figure 2 which shows input to and output from the first node. As described above with reference to step 104 in Figure 1 , one input to the determination is the first input. The first input is related to the UE and indicates a KPI requirement of the UE. A KPI requirement of the UE can herein be understood to mean a KPI requirement associated with the UE and / or a service used by the UE. Thus, the KPI requirement may depend on the UE or the user of the UE, e.g. whether the UE or user is a priority UE or user. The KPI requirement may further depend on the service and / or type of traffic of the UE, e.g., whether the UE is running a delay sensitive service such as URLLC or not. The KPI requirement may comprise one or more requirements, e.g., related to fulfilling a requested QoS. Examples of KPI requirements are requirement related to packet latency, packet loss, throughput, average number of transmission object size, etc.

[0045] In examples, the first input may further indicate one or more of a DRX configuration of the UE, an energy saving mode of the UE and a capability of the UE. Thus, the first node may in addition to the KPI requirements of the UE also use one or more of the DRX configuration of the UE, the energy saving mode of the UE and the capability of the UE, as input when determining candidate cells for the UE. The DRX configuration may be a previous DRX configuration used by the UE e.g., the DRX configuration of the UE when last in connected mode or used in a source cell before handover.

[0046] The energy saving mode may indicate a UE sleep mode or a UE energy consumption state. The UE energy consumption state may be from a set UE energy consumption states in a table. The table may encompass various hardware sleeping functions, each described in a row along with associated metrics such as energy savings, transition time, and energy required to reactivate that hardware. An example of such a table in 3GPP is provided in Table 5.1-3 in 3GPP TR 38.840. Information about energy saving mode may be available from the UE depending on implementation and / or UE vendor. If the energy saving mode of the UE is not available from the UE, standardized models, e.g., from a table such as the one found in Table 5.1-3 in 3GPP TR 38.840 may be used as input.

[0047] The capability of the UE may indicate whether the UE supports DRX / DTX, as well as other service or energy related characteristics of the UE which may affect whether an association between the UE and a cell is suitable or not.

[0048] The first node may obtain the first input in a number of different ways. The first input may e.g., be obtained from one or more of the UE, a node serving the UE, an application serving the UE and a model of the UE. For example, if the determination is performed as part of an initial setup for the UE, the first input may be provided by the UE to the first node either directly or via another node such as e.g., the second node. If the determination is performed as part of a handover procedure for the UE, the first input may be provided by a network access node currently serving the UE. Different parts of the first input may be obtained from different source. The KPI requirements may e.g., be received from the UE via signaling or obtained from a UE-ID of the UE. In examples, the request for candidate cells for the UE from the second node may comprise one or more parts of the first input, e.g., the KPI requirements. If no or limited input is available for the UE, a model of the UE may be used. The model may e.g., be selected based on UE type and may provide UE characteristics such as e.g., energy saving mode.

[0049] With reference to Figure 2, another input to the first node is the second input. As described above with reference to step 104 in Figure 1 , the second input is related to the plurality of cells and indicates energy saving configurations of the plurality of cells, e.g., one or more energy saving configurations per cell in the plurality of cells. In examples, the second input may further indicate one or more of a load of a cell, an energy saving mode of a cell and a channel condition between the UE and a cell. Thus, the first node may in addition to the energy saving configurations of a cell also use one or more of the load, energy saving mode and channel condition associated with the cell as input when determining candidate cells for the UE. The load of the cell may be indicated e.g., with statistics of PRB_ utilization, downlink buffer size or similar. The energy saving mode may be a sleep mode of the cell such as e.g., deep_sleep, light_sleep, and micro_sleep. The sleep modes may be associated with transition times and energy consumption information. The channel condition may be indicated with RSSI or similar measurement quantities. The second input may further indicate information associated with UEs currently served by the cells such as e.g., their KPI requirements.

[0050] The second input may be obtained from one or more of a network access node, UEs and a core network node. The first node may e.g., obtain information indicating load and energy saving mode of a cell from a network access node controlling the cell or a core network node managing one or more of the plurality of cells, while channel condition between the UE and a cell may be obtained from the UE or a network access node controlling the cell. Based on the first input and the second input, the first node determines and output one or more candidate cells and optionally DRX configurations associated with the one or more candidate cells, as shown in Figure 2.

[0051] Figure 3 is a flow chart illustrating process steps in a computer implemented method 200 for supporting establishment of an association between a UE and a cell. The method 200 is performed by a second node in a communication network such as e.g., a wireless communication network. The second node may be, or be comprised in, a network access node, such as e.g., an access node or management node in a RAN.

[0052] Referring to Figure 3, the method 200 comprises, in a first step 202, providing a request for candidate cells for a UE to a first node. The candidate cells are candidates for the UE to be associated with. The request for candidate cells may be triggered for the UE, e.g., when the UE request an initial association to a cell or when the UE or a network access node requests a re-association to a new cell, as will be further described below. In examples, the request may be a control message or an indication sent by the second node to the first node via an external interface or an internal interface between the first node and the second node.

[0053] The method 200 then comprises obtaining, in step 204, a response indicating one or more candidate cells for the UE from the first node. Each candidate cell fulfilling a KPI requirement of the UE and an energy saving condition associated with an energy saving configuration of the candidate cell. The response is obtained in response to the request to the first node and indicates suitable candidate cells for the UE. The candidate cells may be determined as described above with reference to step 104 in Figure 1.

[0054] The method 200 then comprises initiating, in step 206, establishment of an association between the UE and one of the one or more candidate cells. Thus, the second node selects one candidate cell from the one or more candidate cells to be the serving cell of the UE and initiates a procedure to establish an association between the UE and the selected candidate cell. The establishment of the association may be performed in a conventional way, e.g., as specified in the 3GPP standard.

[0055] If the response indicates one candidate cells, establishment of an association between the UE and that cell may be initiated. If the response indicates two or more candidate cells, one of the two or more candidate cells are selected for the UE. The selection may be based on a ranking of the candidate cells indicated in the response. As described above, the candidate cells indicated in the response may be ranked based on energy saving impact. In this case, an establishment of an association may be initiated between the UE and the highest ranked candidate cell.

[0056] The second node may further consider additional information when selecting a cell to serve the UE from two or more candidate cells. The second node may e.g., have information about current number of UEs served by a candidate cell and maximum number of UEs the candidate cell can handle and further base the cell selection on this information such that the maximum number of UEs is not exceeded.

[0057] Referring to step 202 in Figure 3, the request for candidate cells for a UE may be triggered by at least one of an initial set-up request for the UE, a handover request for the UE, an indication of a KPI requirement change for the UE, an indication of nonfulfillment of a KPI requirement for the UE, and an indication of a change in one of the plurality of cells.

[0058] Thus, the second node may provide the request for candidate cells to the first node during an initial association for a non-connected UE or a re-association for a connected UE. For example, the second node may receive an initial set-up request for the UE from the UE directly or via another node and subsequently decide to trigger step 202, i.e., provide a request for candidate cells for the UE to the first node. The request for candidate cells for the UE may further be triggered based on detection that a reassociation to a new cell is needed for the UE. This may be the case e.g., when the serving cell can no longer provide a satisfactory channel quality or fulfil the KPI requirements of the UE. Alternatively, when the KPI requirement of the UE changes e.g., due to a change in service or similar.

[0059] The indication of a change in one of the plurality of cells may be related to a change in load, energy saving mode, configuration such as e.g., transmit power, antenna tilt, etc. Any of these changes in one or more of the plurality of cells may trigger a re-association of the UE, as well as a re-association of one or more other UEs in the area covered by the plurality of cells.

[0060] Referring to step 204 in Figure 3 and step 104a in Figure 1 , when DRX configurations are determined for the candidate cells, the response may further indicate DRX configurations for the UE. Each DRX configuration being associated with a candidate cell. In this case, the establishment of the association may indicate the DRX configuration associated with the selected candidate cell. The UE may hence receive the DRX configuration, to be used once served by the selected candidate cell, during the establishment of the association.

[0061] When an association has been established between the UE and the selected candidate cell, the network access node serving the candidate cell may adapt the DRX configuration of the new UE or a group of served UEs including the new UE to further optimize energy savings in the cell or network access node.

[0062] The methods 100 and 200 are performed to support the establishment of an association between a UE and a cell by finding a suitable candidate cell for the UE. The candidate cell is determined from a plurality of cells. The plurality of cells may be coverage cells and / or capacity cells served by one or more network access nodes in a geographical area. The network access nodes may e.g., be base stations in a HetNet scenario, TRPs in a distributed MIMO scenario or remote radio heads in a cloud RAN scenario.

[0063] Figure 4 shows a non-limiting example of a use case for the methods disclosed herein where a network deployment comprises a network access node with many overlaid cells, e.g., on different frequencies. In the shown example, the network access node serves four cells, a high band cell, an upper mid-band cell, a lower mid-band cell and a lower band cell. Assume a new UE requests initial access from or undergoes a handover to the network access node serving the overlaid cells. In this case, proper association of the UE to a suitable cell can help the UE get its KPIs, but also the overlaid cells to follow their energy saving targets. To support the association the network access node serving the overlaid cells may perform the method 100 and / or 200 to determine candidate cells from the overlaid cells and / or initiate an association with one of the candidate cells. The method 100 and / or 200 may further be performed by another node (not shown) such as e.g., a management or control node in the RAN.

[0064] As discussed above, the method 100 is performed by a first node, and the present disclosure provides a first node that is adapted to perform any or all of the steps of the above discussed method. The first node may comprise a physical or virtual node, and may be implemented in a radio access network node, radio base station, base transceiver station, node B, evolved node B, gNB, access point, access node, radio intelligence controller, computer system, computing device or server apparatus, etc., and / or in a virtualized environment, for example in a cloud, edge cloud, an Open Radio Access Network (O-RAN), or fog deployment. Examples of a virtual node may include a piece of software or computer program, a code fragment operable to implement a computer program, a virtualised function, or any other logical entity.

[0065] Figure 5 is a block diagram illustrating an example first node 300 which may implement the method 100, as illustrated in Figure 1 , according to examples of the present disclosure, for example on receipt of suitable instructions from a computer program 350. Referring to Figure 5, the first node 300 comprises a processor or processing circuitry 302, and may comprise a memory 304 and interfaces 306. The processing circuitry 302 is operable to perform some or all of the steps of the method 100 as discussed above with reference to Figure 1 . The memory 304 may contain instructions executable by the processing circuitry 302 such that the first node 300 is operable to perform some or all of the steps of the method 100, as illustrated in Figure 1. The instructions may also include instructions for executing one or more telecommunications and / or data communications protocols. The instructions may be stored in the form of the computer program 350. In some examples, the processor or processing circuitry 302 may include one or more microprocessors or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, etc. The processor or processing circuitry 302 may be implemented by any type of integrated circuit, such as an Application Specific Integrated Circuit (ASIC), Field Programmable Gate Array (FPGA) etc. The memory 304 may include one or several types of memory suitable for the processor, such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, solid state disk, hard disk drive, etc.

[0066] As discussed above, the method 200 is performed by a second node, and the present disclosure provides a second node that is adapted to perform any or all of the steps of the above discussed method. The second node may comprise a physical or virtual node, and may be implemented in a radio access network node, radio base station, base transceiver station, node B, evolved node B, gNB, access point, access node, radio intelligence controller, computer system, computing device or server apparatus, etc., and / or in a virtualized environment, for example in a cloud, edge cloud, O-RAN, or fog deployment. Examples of a virtual node may include a piece of software or computer program, a code fragment operable to implement a computer program, a virtualised function, or any other logical entity.

[0067] Figure 6 is a block diagram illustrating an example second node 400 which may implement the method 200, as illustrated in Figure 3, according to examples of the present disclosure, for example on receipt of suitable instructions from a computer program 450. Referring to Figure 6, the second node 400 comprises a processor or processing circuitry 402, and may comprise a memory 404 and interfaces 406. The processing circuitry 402 is operable to perform some or all of the steps of the method 200 as discussed above with reference to Figure 3. The memory 404 may contain instructions executable by the processing circuitry 402 such that the second node 400 is operable to perform some or all of the steps of the method 200, as illustrated in Figure 3. The instructions may also include instructions for executing one or more telecommunications and / or data communications protocols. The instructions may be stored in the form of the computer program 450. In some examples, the processor or processing circuitry 402 may include one or more microprocessors or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, etc. The processor or processing circuitry 402 may be implemented by any type of integrated circuit, such as an Application Specific Integrated Circuit (ASIC), Field Programmable Gate Array (FPGA) etc. The memory 404 may include one or several types of memory suitable for the processor, such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, solid state disk, hard disk drive, etc.

[0068] The first node and the second node may be separate nodes or may be implemented in the same node. In examples, the first node may be a function implemented in the second node, e.g., a piece of software or computer program running on the second node. The first node and the second node may be nodes in a communication network such as e.g., a wireless communication network implemented according to the 3GPP standard.

[0069] In some examples of the present disclosure, the first node and the second node may be considered as a system, and examples of the present disclosure provide a system for supporting establishment of an association between a UE and a cell. The establishment of the UE to cell association is supported by finding candidate cells for the UE. An example of such a system is illustrated in Figure 7. Referring to Figure 7, the system 500 comprises a first node 300 as described above and a second node 400 as described above. As summarised in Figure 7, the system obtains a trigger for an association or reassociation of a UE. Based on the trigger, the second node 400 provides a request for candidate cells for the UE to the first node 300. The first node 300 determined one or more candidate cells for the UE from a plurality of cells, as previously described, and provides a response indicating the determined one or more candidate cells to the second node 400. The second node 400 selects a candidate cell from the one or more candidate and initiates establishment of an association between the UE and the selected candidate cell.

[0070] The above functionality may be achieved by causing the first node 300 to perform examples of the method 100 and causing the second node 400 to perform examples of the method 200.

[0071] In some examples, the system 500 may be implemented on one or more network access nodes. In other examples, one or more of first node 300 and the second node 400 could be running in a virtualised environment such as cloud, edge cloud, O-RAN etc. In the O- RAN architecture, the first and / or second node may be implemented within Near RT RAN Intelligent Controller (RIC) or Non-Real Time RIC, e.g., as one or more rApps.

[0072] The methods of the present disclosure may be implemented in hardware, or as software modules running on one or more processors. The methods may also be carried out according to the instructions of a computer program, and the present disclosure also provides a computer readable medium having stored thereon a program for carrying out any of the methods described herein. A computer program embodying the disclosure may be stored on a computer readable medium, or it could, for example, be in the form of a signal such as a downloadable data signal provided from an Internet website, or it could be in any other form.

[0073] It should be noted that the above-mentioned examples illustrate rather than limit the disclosure, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims or numbered embodiments. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim or embodiment, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims or numbered embodiments. Any reference signs in the claims or numbered embodiments shall not be construed so as to limit their scope.

Claims

CLAIMS1 . A computer implemented method (100) performed by a first node in a communication network, the method (100) comprising: obtaining (102) a request for candidate cells for a user equipment, UE, from a second node, wherein the candidate cells are candidates for the UE to be associated with; determining (104) one or more candidate cells for the UE from a plurality of cells, based on a first input indicating a Key Performance Indicator, KPI, requirement of the UE and a second input indicating energy saving configurations of the plurality of cells, wherein a cell is determined to be a candidate cell if the cell fulfills the KPI requirement of the UE and an energy saving condition associated with the energy saving configuration of the cell; and providing (106) a response indicating the determined one or more candidate cells to the second node.

2. A computer implemented method (100) according to claim 1 , wherein an energy saving configuration of a cell indicates one or more of a Discontinuous Reception, DRX, configuration of the cell, a Discontinuous Transmission, DTX, configuration of the cell and a DRX configuration for a UE served by the cell.

3. A computer implemented method (100) according to claim 1 or 2, the method (100) further comprising determining (104a) for cells of the one or more candidate cells a DRX configuration for the UE; and wherein the response further indicates the one or more determined DRX configurations.

4. A computer implemented method (100) according to any one of the preceding claims, wherein the one or more candidate cells are ranked based on energy saving impact; and wherein the response further indicates the ranking of the one or more candidate cells.

5. A computer implemented method (100) according to any one of the preceding claims, wherein the first input further indicates one or more of a DRX configuration of the UE, an energy saving mode of the UE and a capability of the UE.

6. A computer implemented method (100) according to any one of the preceding claims, wherein the first input is obtained from one or more of the UE, a node serving the UE, an application serving the UE and a model of the UE.

7. A computer implemented method (100) according to any one of the preceding claims, wherein the second input further indicates one or more of a load of a cell, an energy saving mode of a cell and a channel condition between the UE and a cell.

8. A computer implemented method (100) according to any one of the preceding claims, wherein the second input is obtained from one or more of a network access node and a core network node.

9. A computer implemented method (100) according to any one of the preceding claims, wherein the determining (104, 104a) is performed using a machine learning, ML, model, and wherein the ML model is a neural network, a multi-armed bandit or a reinforcement learning model.

10. A computer implemented method (200) performed by a second node in a communication network, the method (200) comprising: providing (202) a request for candidate cells for a UE to a first node, wherein the candidate cells are candidates for the UE to be associated with; obtaining (204) a response indicating one or more candidate cells for the UE from the first node, each candidate cell fulfilling a KPI requirement of the UE and an energy saving condition associated with an energy saving configuration of the candidate cell; and initiating (206) establishment of an association between the UE and one of the one or more candidate cells.

11. A computer implemented method (200) according to claim 10, wherein the request is triggered by at least one of an initial set-up request for the UE, a handover request for the UE, an indication of a KPI requirement change for the UE, an indication of nonfulfillment of a KPI requirement for the UE, and an indication of a change in one of the plurality of cells.

12. A computer implemented method (200) according to claim 10 or 11 , wherein the response further indicates DRX configurations for the UE, each DRX configurationbeing associated with a candidate cell, and wherein the establishment of the association indicates the DRX configuration associated with the selected candidate cell.

13. A computer implemented method (200) according to any one of claims 10 to 12, wherein the one or more candidate cells indicated in the response are ranked based on energy saving impact; and wherein an establishment of an association is initiated between the UE and the highest ranked candidate cell.

14. A computer implemented method (100, 200) according to any one of the preceding claims, wherein at least one of the first node and the second node is a network access node.

15. A computer program product comprising a computer readable medium, the computer readable medium having computer readable code embodied therein, the computer readable code being configured such that, on execution by a suitable computer or processor, the computer or processor is caused to perform a method as claimed in any one of the preceding claims.

16. A first node (300) comprising processing circuitry (302) configured to cause the first node (300) to: obtain a request for candidate cells for a UE from a second node (400), wherein the candidate cells are candidates for the UE to be associated with; determine one or more candidate cells for the UE from a plurality of cells based on a first input indicating a KPI requirement of the UE and a second input indicating energy saving configurations of the plurality of cells, wherein a cell is determined to be a candidate cells if the cell fulfills the KPI requirement of the UE and an energy saving condition associated with the energy saving configuration of the candidate cell; and provide a response indicating the determined one or more candidate cells to the second node (400).

17. A first node (300) according to in claim 16, wherein the processing circuitry (302) is further configured to cause the first node (300) to carry out a method (100) according to any one of claims 2 to 9.

18. A second node (400) comprising processing circuitry (402) configured to cause the second node (400) to: provide a request for candidate cells for a UE to a first node (300), wherein the candidate cells are candidates for the UE to be associated with; obtain a response indicating one or more candidate cells for the UE from the first node (300), each candidate cell fulfilling a KPI requirement of the UE and an energy saving condition associated with an energy saving configuration of the candidate cell; and initiate establishment of an association between the UE and one of the one or more candidate cells.

19. A second node (400) according to in claim 18, wherein the processing circuitry (402) is further configured to cause the second node (400) to carry out a method (200) according to any one of claims 11 to 14.

Images