Conditional handover configuration for fast offload during cell shutdown

Abstract

Systems, methods, apparatus, and non-transitory computer readable media for conditional switching configuration for fast offload during cell shutdown. For example, a method includes receiving, with a user equipment, one or more handover configurations from a serving cell. The one or more switching configurations include an energy saving condition switching configuration. At least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection. The method also includes receiving, from the serving cell, an indication of energy saving mode activation at the serving cell. The method also includes selecting a target cell from the one or more candidate target cells based at least in part on the one or more handover configurations and the received indication of the energy saving mode activation at the serving cell.

Description

[0001] This application is a divisional application of the invention patent application with the invention title "Conditional Handover Configuration for Fast Offloading During Cell Shutdown", application date of March 9, 2023, and application number 202380038389.6. Technical Field

[0002] Examples and non-limiting embodiments generally relate to network communication and, more particularly, to handover procedures. Background Art

[0003] As is well known, in network communication, performing cell shutdown can achieve energy savings. Summary of the Invention

[0004] The following abstract is only for illustrative purposes. The abstract is not intended to limit the scope of the claims.

[0005] According to one aspect, a device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the device to at least: receive one or more handover configurations from a serving cell, wherein the one or more handover configurations include an energy-saving conditional handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; receive an indication of activation of an energy-saving mode at the serving cell; and select a target cell from the one or more candidate target cells at least in part based on the one or more handover configurations and the received indication of activation of the energy-saving mode at the serving cell.

[0006] According to one aspect, a method includes: receiving, by a user equipment, one or more handover configurations from a serving cell, wherein the one or more handover configurations include an energy-saving conditional handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; receiving an indication of activation of an energy-saving mode at the serving cell; and selecting a target cell from the one or more candidate target cells at least in part based on the one or more handover configurations and the received indication of activation of the energy-saving mode at the serving cell.

[0007] According to one aspect, an apparatus includes means for performing the following: receiving, from a serving cell, one or more handover configurations, wherein the one or more handover configurations include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; receiving, from the serving cell, an indication of activation of an energy saving mode at the serving cell; and selecting a target cell from the one or more candidate target cells at least in part based on the one or more handover configurations and the received indication of activation of the energy saving mode at the serving cell.

[0008] According to one aspect, a non-transitory computer-readable medium includes program instructions stored thereon that, when executed by at least one processor, cause the at least one processor to: cause reception of one or more handover configurations from a serving cell, wherein the one or more handover configurations include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; cause reception of an indication of initiation of an energy saving mode at the serving cell; and select a target cell from the one or more candidate target cells at least in part based on the one or more handover configurations and the received indication of activation of the energy saving mode at the serving cell.

[0009] According to one aspect, an apparatus includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least: determine to activate an energy saving mode; generate one or more handover configurations, wherein the one or more handover configurations include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; transmit the one or more handover configurations to a user equipment; initiate activation of the energy saving mode; and transmit an indication of activation of the energy saving mode to the user equipment.

[0010] According to one aspect, a method includes: determining to activate an energy saving mode; generating one or more handover configurations, wherein the one or more handover configurations include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; transmitting the one or more handover configurations to a user equipment; starting to activate the energy saving mode; and transmitting an indication of the activation of the energy saving mode to the user equipment. According to one aspect, an apparatus includes means for performing the following: determining to activate an energy saving mode; generating one or more handover configurations, wherein the one or more handover configurations include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; transmitting the one or more handover configurations to a user equipment; starting to activate the energy saving mode; and transmitting an indication of the activation of the energy saving mode to the user equipment.

[0011] According to one aspect, a non-transitory computer-readable medium includes program instructions stored thereon that, when executed by at least one processor, cause the at least one processor to: determine to activate an energy saving mode; generate one or more handover configurations, wherein the one or more handover configurations include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; cause the one or more handover configurations to be transmitted to a user equipment; start to activate the energy saving mode; and cause an indication of the activation of the energy saving mode to be transmitted to the user equipment.

[0012] According to one aspect, a computer program includes instructions stored thereon for at least performing the following: receiving one or more handover configurations from a serving cell, wherein the one or more handover configurations include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; receiving an indication of the activation of the energy saving mode at the serving cell from the serving cell; and selecting a target cell from the one or more candidate target cells based at least in part on the one or more handover configurations and the received indication of the activation of the energy saving mode at the serving cell.

[0013] According to one aspect, a computer program includes instructions stored thereon for at least performing the following: determining to activate an energy-saving mode; generating one or more handover configurations, wherein the one or more handover configurations include an energy-saving condition handover configuration, and wherein at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection; transmitting the one or more handover configurations to a user equipment; starting to activate the energy-saving mode; and transmitting an indication of the activation of the energy-saving mode to the user equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above aspects and many other features are explained in the following description in conjunction with the drawings, wherein:

[0015] Figure 1 is a block diagram of one possible and non-limiting example system in which example embodiments may be practiced;

[0016] Figure 2 is a diagram showing a plurality of features as described herein;

[0017] FIG. 3 is a flowchart showing a plurality of steps as described herein;

[0018] Figure 4 is a diagram showing a plurality of features as described herein;

[0019] Figure 5 is a flowchart showing a plurality of steps as described herein;

[0020] Figure 6 is a flowchart showing a plurality of steps as described herein;

[0021] Figure 7 is a flowchart showing a plurality of steps as described herein; and

[0022] Figure 8 is a flowchart showing a plurality of steps as described herein. DETAILED DESCRIPTION

[0023] The following abbreviations, which may be found in the specification and / or the drawings, are defined as follows:

[0024] 3GPP Third Generation Partnership Project

[0025] 5G Fifth Generation

[0026] 5GC 5G Core Network

[0027] AI Artificial Intelligence

[0028] AMF Access and Mobility Management Function

[0029] BB Baseband

[0030] CE Control Element

[0031] CHO Conditional Handover

[0032] CN Core Network

[0033] CPC Conditional PS Cell Change

[0034] CSI-RS Channel State Information Reference Signal

[0035] CU Central Unit

[0036] DCI Downlink Control Information

[0037] DL Downlink

[0038] DRX Discontinuous Reception

[0039] DTX Discontinuous Transmission

[0040] DU Distributed Unit

[0041] eDRX Extended Discontinuous Reception

[0042] eMBB Enhanced Mobile Broadband

[0043] eMTC Enhanced Machine-Type Communication

[0044] eNB (or evolved Node B (e.g., an LTE base station)

[0045] eNodeB)

[0046] EN-DC E-UTRA-NR Dual Connectivity

[0047] en-gNB or a node that provides NR user plane and control plane protocol termination to the UE En-gNB and acts as the secondary node in EN-DC ES Energy Saving

[0048] ES-CHO Energy Saving Conditional Handover

[0049] E-UTRA Evolved Universal Terrestrial Radio Access, i.e., LTE radio access technology

[0050] gNB (or 5G / NR base station, i.e., a node that provides NR user plane gNodeB) and control plane protocol termination and is connected to the 5GC via the NG interface

[0051] HFN Hyper Frame Number

[0052] HO Handover

[0053] IE Information Element

[0054] I / F Interface

[0055] L1 Layer 1

[0056] LTE Long Term Evolution

[0057] MAC Medium Access Control (m)MIMO (Massive) Multiple-Input Multiple-Output

[0058] ML Machine Learning

[0059] MME Mobility Management Entity

[0060] ng or NG Next Generation

[0061] ng-eNB or Next Generation eNB

[0062] NG-eNB NR New Radio

[0063] N / W or NW Network

[0064] O&M Operation and Maintenance

[0065] OFDM Orthogonal Frequency Division Multiplexing

[0066] OPEX Operating Expenses

[0067] PBCH Physical Broadcast Channel

[0068] PDCP Packet Data Convergence Protocol

[0069] PHY Physical Layer

[0070] PoC Push-to-Talk over Cellular

[0071] PSG Power Saving Group

[0072] PSW Power Saving Window

[0073] RA Registration Area

[0074] RAN Radio Access Network

[0075] RAT Radio Access Technology

[0076] RedCap Reduced Capability

[0077] RF Radio Frequency

[0078] RLC Radio Link Control

[0079] RNA RAN-based notification area

[0080] RRC Radio Resource Control

[0081] RRH Remote Radio Head

[0082] RRM Radio Resource Management

[0083] RS Reference Signal

[0084] RSRP Refers to the Reference Signal Received Power

[0085] RSRQ Reference Signal Received Quality

[0086] RU Radio Unit

[0087] Rx Receiver

[0088] SDAP Service Data Adaptation Protocol

[0089] SFN System Frame Number

[0090] SGW Serving Gateway

[0091] SI System Information

[0092] SIB System Information Block

[0093] SINR Signal-to-Interference-plus-Noise Ratio

[0094] SMF Session Management Function

[0095] SS Synchronization Signal

[0096] SSB Synchronization Signal Block

[0097] TA Tracking Area

[0098] TCI Transmission Configuration Indicator

[0099] TRX Transceiver

[0100] Tx Transmitter

[0101] UE User Equipment (e.g., a wireless device, typically a mobile device)

[0102] UPF User Plane Function

[0103] Steering Figure 1 , this figure shows a block diagram of one possible and non-limiting example in which examples may be practiced. A User Equipment (UE) 110, a Radio Access Network (RAN) node 170, and a network element 190 are shown. In Figure 1In the example, user equipment (UE) 110 communicates wirelessly with a wireless network 100. The UE is a wireless device capable of accessing the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected by one or more buses 127. Each of the one or more transceivers 130 includes a receiver Rx 132 and a transmitter Tx 133. The one or more buses 127 can be an address bus, a data bus, or a control bus, and can include any interconnect mechanism, such as a series of lines on a motherboard or an integrated circuit, an optical fiber, or other optical communication device, etc. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, and the module includes one or both of parts 140-1 and / or 140-2 that can be implemented in many ways. The module 140 can be implemented in hardware as module 140-1, such as being implemented as part of one or more processors 120. The module 140-1 can also be implemented as an integrated circuit or implemented by other hardware such as a programmable gate array. In another example, the module 140 can be implemented as module 140-2, which is implemented as computer program code 123 and executed by one or more processors 120. For example, the one or more memories 125 and the computer program code 123 can be configured to, together with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations described herein. The UE 110 communicates with the RAN node 170 via a wireless link 111.

[0104] In this example, the RAN node 170 is a base station that provides access to the wireless network 100 via a wireless device such as UE 110. The RAN node 170 can be, for example, a 5G base station, also known as New Radio (NR). In 5G, the RAN node 170 can be an NG-RAN node, which is defined as a gNB or an ng-eNB. A gNB is a node that provides NR user plane and control plane protocol termination to the UE and is connected to the 5GC (such as, for example, network element 190) via the NG interface. An ng-eNB is a node that provides E-UTRA user plane and control plane protocol termination to the UE and is connected to the 5GC via the NG interface. The NG-RAN node can include multiple gNBs, and the multiple gNBs can also include a Central Unit (CU) (gNB-CU) 196 and a Distributed Unit (DU) (gNB-DU), and DU 195 in the distributed unit is shown. Note that the DU can include or be coupled to and control a Radio Unit (RU). The gNB-CU is a logical node that hosts the RRC, SDAP, and PDCP protocols of the gNB or controls the operations of one or more gNB-DUs and the RRC and PDCP protocols of the en-gNB. The gNB-CU terminates the F1 interface connected to the gNB-DU. The F1 interface is shown as reference numeral 198, although reference numeral 198 also shows the link between the remote element and the centralized element of the RAN node 170 (such as between the gNB-CU 196 and the gNB-DU 195). The gNB-DU is a logical node that hosts the RLC, MAC, and PHY layers of the gNB or en-gNB, and its operation is partially controlled by the gNB-CU. One gNB-CU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface 198 connected to the gNB-CU. Note that the DU 195 is considered to include a transceiver 160, for example, as part of the RU, but some examples in this regard can make the transceiver 160 as part of a separate RU, for example, under the control of the DU 195 and connected to the DU 195. The RAN node 170 can also be an eNB (evolved Node B) base station for LTE (Long Term Evolution), or any other suitable base station or node.

[0105] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / W I / F) 161, and one or more transceivers 160 interconnected by one or more buses 157. Each of the one or more transceivers 160 includes a receiver Rx 162 and a transmitter Tx 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor 152, the memory 155, and the network interface 161. Note that the DU 195 may also include its own one / more memories and processors, and / or other hardware, but these are not shown.

[0106] The RAN node 170 includes a module 150, and the module includes one or both of parts 150-1 and / or 150-2 that can be implemented in many ways. The module 150 can be implemented in hardware as the module 150-1, such as being implemented as part of one or more processors 152. The module 150-1 can also be implemented as an integrated circuit or implemented by other hardware such as a programmable gate array. In another example, the module 150 can be implemented as the module 150-2, which is implemented as computer program code 153 and executed by one or more processors 152. For example, the one or more memories 155 and the computer program code 153 are configured to, together with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations described herein. Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or implemented separately in the DU 195.

[0107] One or more network interfaces 161 communicate via a network, such as via links 176 and 131. Two or more gNBs 170 can communicate using, for example, the link 176. The link 176 can be wired or wireless or both, and can implement, for example, the Xn interface for 5G, the X2 interface for LTE, or other suitable interfaces for other standards.

[0108] One or more buses 157 can be an address bus, a data bus, or a control bus, and can include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optic or other optical communication devices, wireless channels, etc. For example, one or more transceivers 160 can be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for a gNB implementation for 5G, where other elements of the RAN node 170 may be physically located in a different location from the RRH / DU, and one or more buses 157 can be partially implemented as, for example, a fiber optic cable or other suitable network connection to connect other elements of the RAN node 170 (e.g., a central unit (CU), gNB-CU) to the RRH / DU 195. The reference numeral 198 also indicates those suitable network links.

[0109] Note that the description herein indicates that a "cell" performs multiple functions, but it should be clear that the devices forming the cell will perform the multiple functions. A cell forms part of a base station. That is, each base station can have multiple cells. For example, a single carrier frequency and associated bandwidth can have three cells, each cell covering one-third of a 360-degree area, such that the coverage area of a single base station covers an approximately elliptical or circular shape. Additionally, each cell can correspond to a single carrier, and a base station can use multiple carriers. Thus, if each carrier has three 120-degree cells and there are two carriers, then the base station has a total of six cells.

[0110] The wireless network 100 may include one or more network elements 190, which may include core network functionality and provide connectivity to other networks such as a telephone network and / or a data communication network (e.g., the Internet) via one or more links 181. Such core network functionality of 5G may include one or more Access and Mobility Management Functions (AMF) and / or one or more User Plane Functions (UPF) and / or one or more Session Management Functions (SMF). Such core network functionality of LTE may include MME (Mobility Management Entity) / SGW (Serving Gateway) functionality. These are only illustrative functions that the network element 190 may support, and note that both 5G functions and LTE functions may be supported. The RAN node 170 is coupled to the network element 190 via the link 131. The link 131 may be implemented as, for example, the NG interface for 5G, or the S1 interface for LTE, or other suitable interfaces for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / WI / F) 180 interconnected by one or more buses 185. One or more memories 171 include computer program code 173. One or more memories 171 and the computer program code 173 are configured to cause the network element 190 to perform one or more operations together with one or more processors 175.

[0111] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single software-based management entity (virtual network). Network virtualization involves platform virtualization, which is usually combined with resource virtualization. Network virtualization is classified as: external network virtualization that combines many networks or parts of a network into virtual units, or internal network virtualization that provides network-like functionality to software containers on a single system. Note that the virtualized entities resulting from network virtualization are still implemented to some extent using hardware such as processors 152 or 175 and memories 155 and 171, and such virtualized entities also produce technical effects.

[0112] The computer-readable memories 125, 155, and 171 can be of any type suitable for the local technical environment and can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memories, magnetic memory devices and systems, optical memory devices and systems, fixed memories, and removable memories. The computer-readable memories 125, 155, and 171 can be devices for performing various storage functions. As a non-limiting example, the processors 120, 152, and 175 can be of any type suitable for the local technical environment and can include one or more of the following: general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), and processors based on multi-core processor architectures. The processors 120, 152, and 175 can be devices for performing various functions, such as controlling the UE 110, the RAN node 170, and other functions as described herein.

[0113] Generally, various embodiments of the user equipment 110 can include, but are not limited to, cellular phones such as smart phones, tablet computers, personal digital assistants (PDAs) with wireless communication capabilities, portable computers with wireless communication capabilities, image capture devices such as digital cameras with wireless communication capabilities, gaming devices with wireless communication capabilities, music storage and playback devices with wireless communication capabilities, Internet devices that allow wireless Internet access and browsing, tablet computers with wireless communication capabilities, and portable units or terminals that combine such functions in combination.

[0114] The features described herein generally relate to network energy-saving enhancements in 5G NR and future technologies (e.g., 6G). More specifically, the features described herein can generally relate to the conditional handover feature of 5G NR, which can be used during cell shutdown to achieve network energy savings.

[0115] Reducing the energy consumption of mobile networks, especially the energy consumption of the RAN, which accounts for the largest part of the total network energy consumption, has received extensive attention. Research on network energy savings will be carried out in 3GPP Rel.18 and may aim to identify network energy-saving technologies in the time domain, frequency domain, spatial domain, and / or power domain that target both transmission and reception. Potential support / feedback from the UE, potential UE assistance information, and information exchange / coordination through network interfaces may also fall within the scope of the research (RP-213554).

[0116] In Rel.18, there will also be an AI / Machine Learning (ML) work item (RP-213602) for NG-RAN based on Rel.17 research, and the research project description is included in RP-201620 "NR and EN-DC Data Collection Enhancement Research". The work item aims to specify data collection enhancements and signaling support within the existing NG-RAN interfaces and architectures for many AI / ML-based use cases. One of the use cases is energy saving.

[0117] Energy saving functionality has been introduced to reduce network energy consumption and energy-related operating expenses whenever possible. Energy saving deployments consider capacity-boosting cells that are deployed on top of coverage cells to enhance the capacity of single- or dual-connected E-UTRA or NR. These cells are allowed to be optimized by turning off when capacity is not required and reactivating as needed. The turning off of cells can be performed by OAM and the NG-RAN nodes that own the capacity cells, and the NG-RAN nodes can autonomously turn off cells using, for example, cell load information. Turning off cells during low-load periods is one of the most effective means of achieving network energy saving because all power-consuming hardware components of the cell can be turned off, and thus significant energy consumption reduction can be achieved. In the cell shutdown scenario, the power consumption may be reduced by 10 - 15% when the cell is shut down compared to when the cell is not shut down. Now refer to Figure 2 , which shows an example of cell shutdown characteristics. A Power Saving Group (PSG) is a group of cells (i.e., frequency layers) that cover the same area. In Figure 2 's example, PSG-1 includes two cells 210a and 210b that cover the same area with different frequencies; PSG-2 includes two cells 220a and 220b that cover the same area with different frequencies; and PSG-3 includes two cells 230a and 230b that cover the same area with different frequencies. Although in Figure 2 's example, each PSG consists of two frequency layers, this example is non-restrictive; more or fewer frequency layers may be included in more or fewer PSGs.

[0118] Cells can be energy-saving by turning off. Energy saving can lead to savings in operating expenditure (OPEX). For each PSG, the load can be compared with one or more thresholds. If the load is below the threshold, the cell can be turned off. If the load is greater than another threshold, the cell can be turned on again. The thresholds can be predefined. The comparison of the load of the PSG can be made with the thresholds. Under low-traffic conditions, the (multiple) layers of the PSG can be turned off without overly degrading network performance while saving energy.

[0119] As described above, the cell shutdown process can provide potential energy savings. Additionally, other means can be employed to save energy while the cell is still active. For example, radio frequency (RF) path micro-cutting (such as micro-discontinuous transmission (DTX)) can result in a 10 - 20% reduction in power consumption (e.g., more than 40% reduction under no-load conditions). This means that when there is no transmission, the RF power consumption can be reduced with RF path micro-cutting. As yet another example, through (massive) multiple-input multiple-output ((m)MIMO) muting, the power consumption can be reduced by 10 - 30%. In the first case, for example, half of the transceivers can be shut down horizontally. In the second case, for example, half of the transceivers can be shut down vertically. If the baseband components can also be shut down, the power consumption can be further reduced.

[0120] The features described herein generally relate to conditional handover (CHO) defined in 5G NR Release 16. This new handover process can allow the UE to perform a handover when certain handover conditions are met. In other words, CHO is a handover performed by the UE when the configured execution conditions are satisfied, without the need for a handover command from the network. This process can have the technical effect of avoiding the latency associated with network control processes and reducing handover failures.

[0121] Once the decision is made to shut down the cell (e.g., by autonomous cell shutdown or by the operation and management function (O&M)), the UEs currently connected to the cell need to be unloaded from the cell before the shutdown can be completed. This can be done by switching each connected UE to an adjacent cell, which may have overlapping coverage and be able to accommodate the additional load using conventional handovers. The adjacent cell may belong to a coverage layer or to another frequency layer (e.g., in the case where the shutdown is performed at the PSG of a given frequency layer). If the unloading is not completed before the cell shutdown, a handover (HO) failure may occur. Faster unloading can have the technical effect of increasing the reduction in power consumption.

[0122] However, offloading traffic from a cell using conventional handovers can be rather slow. The process may require multiple consecutive steps to gradually reduce the transmit power of, for example, a Synchronization Signal Block (SSB), which in turn may reduce the received signal strength observed by the UE (Reference Signal Received Power / Reference Signal Received Quality (RSRP / RSRQ)). A UE in RRC connected mode can perform radio resource management (RRM) measurements (RSRP / RSRQ) of the serving cell and neighboring cells and report these measurements to the network. This can help the network identify relevant neighboring cells available for the UE to handover given the radio conditions of the UE. For example, when the RSRP of a target cell becomes better than the RSRP of the serving cell by a defined offset, the UE can trigger an A3 event (triggered when a neighboring cell becomes better than the serving cell by an offset) and send a measurement report (indicating the best candidate cell) to the serving cell. After determining the target cell for a given UE based on the UE RRM measurement report, the serving cell can finally prepare the selected cell via Xn and trigger the handover by sending a handover command to the UE. However, the handover process may be affected by handover failures. Whenever a handover fails, the UE should perform cell selection and then perform reconstruction. Thus, the UE can perform reconstruction on the source cell and may have to repeat the handover process (i.e., to the target cell) (e.g., if the handover conditions persist).

[0123] Example embodiments of the present disclosure can have a technical effect of allowing a cell to be offloaded faster before cell shutdown (e.g., avoiding HO failures) thereby improving power consumption reduction.

[0124] According to Section 5.3.5.13, "Conditional Reconfiguration", of TS 38.331, the CHO configuration provided by the source gNB to the UE (ConditionalReconfiguration-r16 in RRCReconfig) can include the following information elements (IEs): candidate target special cells ready for conditional handover (generated by candidate gNBs); execution criteria (e.g., criteria that the UE should use for conditional reconfiguration execution generated by the source gNB (i.e., to control when to trigger CHO)); and / or RS type (based on SSB or Channel State Information Reference Signal (CSI-RS)) (e.g., the RS that the UE should use to obtain beam and cell measurement results for evaluating conditional reconfiguration execution conditions). Note that CHO only supports a single reference signal type and at most two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) can be configured simultaneously for evaluating the CHO execution conditions of a single candidate cell.

[0125] It should be noted that TS 38.331 stipulates that if the UE is configured with CHO configuration and before the CHO execution conditions are met, the UE may receive a HO command from the gNB. The UE may trigger a handover based on the received HO command without waiting for any CHO conditions to be satisfied. This means that traditional HO commands may take precedence over CHO configurations (if configured).

[0126] Up to 8 CHO configurations can be configured for the UE (depending on UE capabilities). Each CHO configuration may consist of a CHO ID, 1 to 2 MeasIDs (e.g., one with RSRP and the other with RSRQ) and / or (intra-RAT) HO commands.

[0127] Once triggered, the CHO can be executed as a normal handover.

[0128] Contrary to the exemplary embodiments of the present disclosure, in traditional CHO, the UE may start evaluating the CHO execution conditions when receiving the CHO configuration and may stop evaluating the execution conditions after performing the handover.

[0129] Referring now to Figure 3, a conditional handover scenario within the basic access and mobility management function / user plane function (AMF / UPF) is shown, as described in TS 338.300. At 302, user data may be transmitted between the UE and the source gNB. At 304, user data may be transmitted between the source gNB and the UPF. At 306, mobility control information may be provided by the AMF to the source gNB. At 308, a measurement control report may be transmitted between the UE and the source gNB. At 310, the source gNB may make a CHO decision, for example, based on the information in the measurement and control report. At 312, the gNB may send one or more handover requests to the target gNB. At 314, the source gNB may send one or more handover requests to other potential target gNBs; this step may be optional. At 316, the target gNB may perform admission control. At 318, other potential target gNBs may optionally perform admission control. At 320, the target gNB may send one or more handover request responses to the source gNB. At 322, other potential target gNBs may send one or more handover request responses to the source gNB. At 324, the source gNB may send an RRC reconfiguration message to the UE. At 326, the UE may send an RRC reconfiguration complete message to the source gNB. Steps 302 to 326 may be considered part of the handover preparation 350.

[0130] At 328, the UE may evaluate the CHO conditions. At 330, the UE may detach from the old cell (source gNB) and synchronize to the new cell (target gNB or other potential target gNBs). At 332, the source gNB may optionally send an early status transfer to other potential target gNBs. At 334, the UPF may send user data to the source gNB, and the source gNB may optionally forward the user data to other potential target gNBs. At 336, the UE, the source gNB, and the target gNB may complete the CHO handover. Steps 328 to 336 may be considered part of the handover execution 360.

[0131] At 338, the target gNB may send a handover success message to the source gNB. At 340, the source gNB may perform an SN status transfer to the target gNB. At 342, the UPF may send user data to the source gNB, and the source gNB may forward the user data to the target gNB. At 344, the source gNB may send a handover cancellation message to the target gNB and optionally to other potential target gNBs. Steps 338 to 344 may be considered part of the handover completion 370.

[0132] Now referring to Figure 4 , an example of the ConditionalReconfiguration IE (410) of the configuration that can be used to add, modify, and / or release condition reconfiguration is shown (TS 38.423). As described in the ConditionalReconfiguration field description (420), if the selected cell is a target candidate cell and is the first cell selection after a failure, the attemptCondReconfig field can be used to enable the UE to perform conditional reconfiguration. The condReconfigToAddModList field can be used to provide a list of configurations of candidate special cells to be added or modified for CHO or CPC. The condReconfigToRemoveList field can be used to provide a list of configurations of candidate special cells to be removed.

[0133] Part of the handover request to prepare resources from the source NG-RAN node to the target NG-RAN node is shown in Table 1:

[0134]

[0135]

[0136] Table 1

[0137] "Estimated arrival probability" may enable the target node to apply some statistical resource optimization based on the estimated arrival probability (where 100% can be interpreted as the UE arriving deterministically as in "classical HO").

[0138] The technical effect of the exemplary implementation of the present disclosure may be to achieve enhanced condition switching to save energy.

[0139] In one exemplary implementation, the network may configure one or more energy-saving specific handover (ES-CHO) configurations for a UE in the RRC connected state, and these configurations may include parameters optimized for energy saving. The technical effect of the ES-CHO configuration may be to be able to quickly offload the UE to a different cell. In one exemplary implementation, when the serving cell (such as a capacity cell) enters one or more corresponding "energy-saving modes" (such as "cell shutdown", "network transmit power reduction", "mMIMO transmit antenna element silencing", etc.), the UE may use the ES-CHO configuration.

[0140] Using such ES-CHO configurations may have the technical effect of being able to quickly offload the UE to a different cell (compared to traditional HO), which is necessary before the cell can enter the new mode, and in turn may allow the cell to achieve greater energy-saving potential. This benefit may be particularly important when a more dynamic time adaptability of the power-saving mode is expected as part of the evolution of the 3GPP energy-saving solution (e.g., leveraging the Rel.18 energy-saving study (RP-213554)).

[0141] In one exemplary implementation, the ES-CHO configuration may include one or more candidate target cells. The one or more candidate target cells may include at least one of the following: a cell associated with the overlay of the serving cell, or a cell in a frequency layer with a lower priority than the frequency layer of the serving cell to enter a given energy-saving mode (such as cell shutdown) (e.g., a frequency layer lower than the serving layer). For example, the target cell assignment may be based on the network shutdown policy and / or network deployment (e.g., depending on which frequency layers are shut down and the shutdown order, and which (lower) frequency layer provides coverage when a given (higher) frequency layer is shut down). Each "energy-saving" mode may be associated with a dedicated ES-CHO configuration.

[0142] In one exemplary implementation, the network indication may be used to trigger the UE application of the ES-CHO configuration. In other words, the serving cell may use any combination of the following options to indicate when the ES-CHO "command" can be executed by the UE (i.e., when the ES-CHO configuration must be applied):

[0143] Implicit indication: Whenever the serving cell indicates that it is entering / applying an "energy-saving" mode associated with the CHO configuration received by the UE, the UE may execute the ES-CHO command. In one exemplary implementation, the network indication of the current "energy-saving" mode may be provided via system information.

[0144] Explicit indication: The serving cell may explicitly indicate the activation of the ES-CHO configuration, or similarly, may explicitly indicate network offloading (e.g., deciding to power off). In one example implementation, these indications may be provided by downlink control information (DCI) / MAC CE.

[0145] Time-based indication: The ES-CHO configuration may include the (predicted) time when it should be implemented. This may have the technical effect of giving the cell an opportunity to serve traffic when the cell has planned to power off in the near future. In one example implementation, the time may be a system frame number (SFN) or a hyperframe number (HFN). Additionally or alternatively, the time may be provided using the number of (predicted) time units from the future (e.g., after receiving the ES-CHO configuration) until the ES-CHO configuration should be applied.

[0146] In one example implementation, the UE may select a target cell for ES-CHO. When the serving cell indicates that an ES-CHO command associated with a certain energy-saving mode must be executed, the UE may determine the target cell based on any of the following options, where the options may be selected based on a capacity / frequency layer decision:

[0147] Option #1 / Default (the target cell may be selected by the UE from the configured cells based on radio measurements (e.g., RRM measurements)). The UE may collect RRM measurements of the target cell included in the corresponding ES-CHO configuration and may select the target cell for ES-CHO from the configured target cells based on the collected RRM measurements. In one example implementation, the ES-CHO configuration may contain radio conditions to be evaluated.

[0148] Option #2 (the target cell may be selected by the UE based on predefined / previously provided information and / or network configuration). The UE may select the target cell for ES-CHO without performing RRM measurements, but based on: predefined / stored information of the (suitable) target cell among the potential target cells provided in the ES-CHO configuration at the UE; and / or predefined / stored information at the network, as well as the network configuration and selection criteria of the target cell (in one example implementation, the ES-CHO configuration may contain a list of target cells, where each target cell may be associated with a given transmission configuration indicator (TCI) state / downlink (DL) beam of the serving cell (based on SSB / CSI-RS) and / or associated with the RSRP value of the serving cell). Then, the UE may select the target cell corresponding to its serving beam (TCI state) / RSRP level. Additionally or alternatively, the target cell selection may be performed based on the TCI state associated with the serving cell.

[0149] In one example implementation, the selection of a target cell can be optimized using AI / ML. AI / ML can be used to train the capacity / frequency layer such that the UE can perform the selection of the target cell for UE-CHO according to the example implementation described above.

[0150] As described above, machine learning tools (such as neural networks) can be used in an increasing number of applications for different types of devices (such as mobile phones). Neural networks and other machine learning tools may be able to learn attributes from input data in a supervised manner or in an unsupervised manner. Such learning may be the result of a training algorithm or the result of a meta-level neural network that provides a training signal.

[0151] The training algorithm may consist of changing some properties of the neural network such that the output of the neural network is as close as possible to the desired output. Training may include changing the properties of the neural network so as to minimize or reduce the error of the output, also known as the loss. Examples of loss include mean squared error (MSE), cross entropy, etc. In recent deep learning techniques, training is an iterative process in which, in each iteration, the algorithm modifies the weights of the neural network to gradually improve the output of the network, i.e., gradually reduce the loss.

[0152] Training a neural network may include an optimization process, but the ultimate goal of machine learning is different from the typical goal of optimization. In optimization, the goal is to minimize the loss. In machine learning, generally, in addition to the goal of optimization, the goal is to have the model learn the properties of the data distribution from a finite training data set. In other words, the training process is additionally used to ensure that the neural network learns to use the finite training data set so as to learn to generalize to data that has not been seen before, i.e., data that has not been used to train the model. This additional goal is usually referred to as generalization. In practice, the data can be divided into at least two sets: a training set and a validation set. The training set can be used to train the network, i.e., to modify its learnable parameters so as to minimize the loss. The validation set can be used to check the performance of the neural network using data that has not been used to minimize the loss (i.e., is not part of the training set), where the performance of the neural network using the validation set can be an indication of the final performance of the model. The errors on the training set and the validation set can be monitored during the training process to understand whether the neural network is actually learning and whether the neural network is learning to generalize. In the case where the network is learning, the training set error should decrease. If the network is not learning, the model may be underfitting. In the case where the network is learning to generalize, the validation set error should decrease and not be much higher than the training set error. If the training set error is low, but the validation set error is much higher than the training set error, or the validation set error does not decrease, or even increases, the model may be overfitting. Overfitting may mean that the model has memorized the properties of the training set and performs well only on that set, but performs poorly on the set that has not been used to adjust its parameters. In other words, the model has not learned to generalize.

[0153] In an example implementation, the capacity / frequency layer may establish a confidence level (probability) regarding its knowledge of the overlapping radio environment provided to the coverage / frequency layer and the target cells in the coverage / frequency layer suitable for offloading a given UE in the case of a handover. In an example implementation, UE RSRP / RSRQ measurements of the strongest neighboring cells and the UE location (exact coordinates, beam information, etc.) may be used to map the location / area / beam in the energy saving (ES) cell to the best target cells in the coverage / frequency layer, where the UE may be offloaded during the next cell change. As an alternative, the capacity cell may use the UE trajectory prediction information calculated / predicted by the capacity cell, either alone or in combination with UE measurements (e.g., UE RSRP / RSRQ measurements of the strongest neighboring cells, UE location information, etc.), to determine the best coverage cell to which the UE traffic should be offloaded in the case of cell shutdown. For example, if the predicted UE trajectory at the capacity cell can determine the next (coverage) cell with a high probability, this may allow the capacity cell to establish a high confidence level regarding the suitable target cells in the coverage / frequency layer for offloading a certain UE in the case of a handover. In an example implementation, the confidence level (probability) value may be updated based on feedback regarding selected options corresponding to different UE locations and handover performance, e.g., related to UE performance in terms of bit rate, packet loss rate, latency, etc. of the handover UE. In an example implementation, if the confidence level (probability) is higher than a threshold, the UE may select a target cell based on predetermined information and / or network configuration. In an example implementation, if the confidence level (probability) is lower than or equal to the threshold, the UE may select a target cell based on RRM measurements. The threshold may be selected as a high value, e.g., 90% confidence level.

[0154] In an example implementation, the target cell may be ready for ES-CHO / prepare for ES-CHO. In an example implementation, the target cell preparation may be performed according to a traditional process and add a power saving trigger / reason and the (predicted) time when the power saving mode will be applied if available. The target gNB may optimize RRM resource reservation based on the received information. Additionally or alternatively, information regarding CHO handover preparation may be added to the cell deactivation indication sent to the neighboring gNB via the Xn / X2 interface. The information regarding CHO handover preparation may include a list of the currently active UEs to be offloaded to the gNB (i.e., the UEs for which the neighboring gNB is configured as the target cell for offloading-based CHO).

[0155] Now referring to Figure 5 , an example signaling flowchart according to an example implementation of the present disclosure is shown. The signaling flowchart includes exchanges between a UE that may be in the RRC_Connected state and the serving gNB.

[0156] At 510, the serving gNB may decide / determine to use ES-CHO during cell shutdown. At 512, the serving gNB may transmit a handover request to the target gNB. The handover request may include an ES-CHO information request, and the ES-CHO information request includes a cell shutdown trigger. This can be regarded as an example where the target cell preparation can be performed according to the traditional process and add a power saving trigger / reason and the (predicted) time when the power saving mode will be applied if available. At 514, the target gNB may perform admission control. At 516, the target gNB may transmit a handover request response to the serving gNB. At 520, the serving gNB may generate an ES-CHO configuration. The ES-CHO configuration may include information for target cell selection. At 522, the serving gNB may transmit an RRCReconfig message to the UE. The RRCReconfig message may include the ES-CHO configuration, and the ES-CHO configuration may include the target gNB for offloading, the target cell for offloading, and / or information for target cell selection. In an example implementation, the information for target cell selection may be at least partially based on the handover request response. At 524, the UE may transmit an RRCReconfigComplete message to the serving gNB. At 526, the UE may store the ES-CHO configuration without applying it. For example, the conditions for applying the ES-CHO configuration may not have occurred yet.

[0157] At 530, the serving gNB may receive / detect an energy saving mode trigger. For example, the energy saving mode trigger may be a cell shutdown trigger. Other types of energy saving mode triggers may be possible, and those of ordinary skill in the art can conceive of them (such as triggers for "cell shutdown", triggers for "network transmit power reduction", triggers for "mMIMO transmit antenna element silencing", etc.). At 532, the serving gNB may transmit a deactivation indication to the target gNB. The deactivation indication may include an ES-CHO information request. This can be an example where information about CHO handover preparation is added to the cell deactivation indication sent to an adjacent gNB via the Xn / X2 interface. At 534, the target gNB may perform admission control. At 536, the target gNB may transmit a handover request response to the serving gNB. At 540, the serving gNB may transmit a cell shutdown indication to the UE. For example, the indication may be part of the system information. In an example implementation, the indication may be at least partially based on the handover request response. At 542, the UE may evaluate the ES-CHO configuration and select a target cell based on the received information. The UE may separate from the serving cell and synchronize with the (selected) target cell. At 550, ES-CHO may be completed. At 560, the target gNB may transmit feedback regarding ES-CHO to the serving gNB.

[0158] Now refer to Figure 6, a flowchart of an example network algorithm for updating the confidence level of target cell selection for UE offloading during the energy saving operation of a source node. The source node may have an initial confidence, 610, for the best candidate target cell for a given UE or a group of UEs at a given location. This can be achieved through network configuration or through some initial guesses made by the source unit, e.g., by leveraging an ML model available at the source. Initially, such a guess / confidence may not always be accurate enough, and thus the source node can update / improve the guess / confidence through, e.g., UE measurements (620) that can achieve determining the strongest candidate target cell for different UEs and UE locations, and through feedback information (620) from the target node regarding the actual UE performance after a handover. This information can help the source node train its available ML model (630). When the source cell has a good enough confidence in the best target node for a given UE / a group of UEs at a specific location, the source cell can reduce or turn off the RRM measurements for this UE / a group of UEs (i.e., configure the UE to operate under option #2 of embodiment #3) (650). In other words, when the new confidence is greater than a threshold (640), the source cell can cause the UE to reduce / stop using RRM measurements and can instead cause the UE / to enable the UE to select the target cell based on predetermined information and / or network configuration (650). If the UE has not performed RRM measurements before, it can be instructed to continue omitting the execution of RRM measurements.

[0159] In the absence of RRM measurements, e.g., through feedback information regarding UE performance after a handover, the source cell can still determine that its confidence in the best target has decreased. The performance degradation (640) can trigger the source node to re - turn on the RRM measurements for a given UE (or a group of UEs at a given location) by forcing these UEs to operate under option #1 of embodiment #3 (660). The RRM measurements can also provide input to the source cell to retrain the source cell's ML model, which determines the best candidate target cell for a given UE or a group of UEs located at a specific location. In other words, if it is determined that the confidence is below the threshold (640), the source cell can determine that the initial confidence regarding the target is equal to the new confidence regarding the target, and can enable the UE / to enable the UE to select the target cell based on the RRM measurements.

[0160] Figure 7Illustrates potential steps of an example method 700. The example method 700 may include: receiving one or more handover configurations from a serving cell, where the one or more handover configurations include an energy saving condition handover configuration, and where at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection, 710; receiving an indication of activation of an energy saving mode at the serving cell from the serving cell, 720; and selecting a target cell from the one or more candidate target cells based at least in part on the one or more handover configurations and the received indication of activation of the energy saving mode at the serving cell, 730.

[0161] Figure 8 Illustrates potential steps of an example method 800. The example method 800 may include: determining to activate an energy saving mode, 810; generating one or more handover configurations, where the one or more handover configurations include an energy saving condition handover configuration, and where at least one of the one or more handover configurations includes at least one of an indication of one or more candidate target cells or information for target cell selection, 820; transmitting the one or more handover configurations to a user equipment, 830; starting to activate the energy saving mode, 840; and transmitting an indication of activation of the energy saving mode to the user equipment, 850.

[0162] According to one example implementation, a device may include: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the device to at least: receive one or more handover configurations from a serving cell, where the one or more handover configurations may include an energy saving condition handover configuration, and where at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; receive an indication of activation of an energy saving mode at the serving cell from the serving cell; and select a target cell from the one or more candidate target cells based at least in part on the one or more handover configurations and the received indication of activation of the energy saving mode at the serving cell.

[0163] The indication of activation of the energy saving mode may be included in a broadcast message.

[0164] The example device may further be configured to: disconnect from the serving cell; and synchronize with the selected target cell.

[0165] At least one of the one or more handover configurations may further include an indication of one or more measurements to be performed.

[0166] The example device may also be configured to: perform at least one of the one or more measurements; and select the target cell at least in part based on the result of the at least one measurement that has been performed.

[0167] Selecting the target cell may include the example device also being configured to: select the target cell at least in part based on one of the following: predetermined information associated with the target cell located at the device, or the information for target cell selection, which may include at least one of the following: a transmission configuration indicator state associated with the serving cell or the target cell, a reference signal received power value associated with the serving cell or the target cell, a downlink beam of the serving cell or the target cell, or a selection criterion.

[0168] The example device may be in a radio resource control connected state.

[0169] The indication of the activation of the energy saving mode at the serving cell may include an indication of at least one of the following: cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0170] The indication of the one or more candidate target cells may be at least in part based on at least one of one or more network shutdown policies of the serving cell, one or more frequency layers that have been shut down of the serving cell, the shutdown order of the one or more frequency layers that have been shut down of the serving cell, or a frequency layer that belongs to the same power saving group as at least one of the one or more frequency layers that have been shut down of the serving cell.

[0171] The example device may also be configured to: select an energy saving condition handover configuration among the one or more handover configurations at least in part based on the indication of the activation of the energy saving mode at the serving cell, wherein selecting the target cell may also be based on the selected energy saving condition handover configuration.

[0172] The example device may also be configured to: receive an indication of when the one or more handover configurations will be applied, wherein the indication may include at least one of the following: the indication of the activation of the energy saving mode at the serving cell; a network offloading indication; an indication of the activation of the one or more handover configurations; or an indication of the time to enforce the one or more handover configurations, which may include at least one of a system frame number, a hyperframe number, or a number of time units.

[0173] The network offloading indication or the indication of the activation of the one or more handover configurations may include one of downlink control information or a media access control control element.

[0174] According to one aspect, an example method may be provided, which includes: receiving, by a user equipment, one or more handover configurations from a serving cell, where the one or more handover configurations may include an energy saving condition handover configuration, and at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; receiving an indication of activation of an energy saving mode at the serving cell from the serving cell; and selecting a target cell from the one or more candidate target cells at least partially based on the one or more handover configurations and the received indication of activation of the energy saving mode at the serving cell.

[0175] The indication of activation of the energy saving mode may be included in a broadcast message.

[0176] The example method may further include: disconnecting the user equipment from the serving cell; and synchronizing the user equipment with the selected target cell.

[0177] The at least one of the one or more handover configurations may further include an indication of one or more measurements to be performed.

[0178] The example method may further include: performing at least one of the one or more measurements; and selecting the target cell at least partially based on the result of the at least one performed measurement.

[0179] Selecting the target cell may include: selecting the target cell at least partially based on at least one of the following: predetermined information associated with the target cell located at the user equipment, or the information for target cell selection, where the information may include at least one of the following: a transmission configuration indicator status associated with the serving cell or the target cell, a reference signal received power value associated with the serving cell or the target cell, a downlink beam of the serving cell or the target cell, or a selection criterion.

[0180] The user equipment may be in a radio resource control connected state.

[0181] The indication of activation of the energy saving mode at the serving cell may include an indication of at least one of the following: cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0182] The indication of the one or more candidate target cells may be at least partially based on one or more network shutdown policies of the serving cell, one or more shutdown frequency layers of the serving cell, the shutdown order of the one or more shutdown frequency layers of the serving cell, or at least one of the frequency layers belonging to the same power saving group as at least one of the one or more shutdown frequency layers of the serving cell.

[0183] The example method may further include: selecting an energy saving condition handover configuration from the one or more handover configurations at least partially based on the indication of the activation of the energy saving mode at the serving cell, wherein the selection of the target cell may also be based on the selected energy saving condition handover configuration.

[0184] The example method may further include: receiving an indication of when the one or more handover configurations will be applied, wherein the indication may include at least one of the following: the indication of the activation of the energy saving mode at the serving cell; a network offloading indication; an indication of the activation of the one or more handover configurations; or an indication of the time to enforce the one or more handover configurations, which may include at least one of a system frame number, a superframe number, or a number of time units.

[0185] The network offloading indication or the indication of the activation of the one or more handover configurations may include one of downlink control information or a media access control control element.

[0186] According to one example implementation, an apparatus may include: circuitry configured to perform the following: receive one or more handover configurations from a serving cell, wherein the one or more handover configurations may include an energy saving condition handover configuration, wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; receive an indication of the activation of an energy saving mode at the serving cell from the serving cell; and select a target cell from the one or more candidate target cells at least partially based on the one or more handover configurations and the received indication of the activation of the energy saving mode at the serving cell.

[0187] According to an example implementation, a device may include: processing circuitry; a memory circuitry including computer program code, the memory circuitry and the computer program code being configured to, together with the processing circuitry, enable the device to: receive one or more handover configurations from a serving cell, wherein the one or more handover configurations may include an energy saving condition handover configuration, wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; receive an indication of activation of an energy saving mode at the serving cell from the serving cell; and select a target cell from the one or more candidate target cells at least in part based on the one or more handover configurations and the received indication of activation of the energy saving mode at the serving cell.

[0188] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) only hardware circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as, where applicable: (i) combinations of analog and / or digital hardware circuits with software / firmware and (ii) any part of a hardware processor with software (including a digital signal processor, software, and memory that work together to enable a device, such as a mobile phone or server, to perform various functions); and (c) hardware circuits and / or processors that require software (such as firmware) to operate, but where the software may be absent when not needed to operate. This definition of circuitry applies to all uses of this term in this application (including in any claims). As another example, as used in this application, the term "circuitry" also covers implementations of only hardware circuits or processors (or multiple processors) or a part of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term "circuitry" also encompasses, for example and where applicable to a particular claim element, a baseband integrated circuit or a processor integrated circuit of a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0189] According to an example implementation, a device may include means for performing the following: receiving one or more handover configurations from a serving cell, wherein the one or more handover configurations may include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; receiving an indication of activation of an energy saving mode at the serving cell; and selecting a target cell from the one or more candidate target cells at least in part based on the one or more handover configurations and the received indication of activation of the energy saving mode at the serving cell.

[0190] The indication of activation of the energy saving mode may be included in a broadcast message.

[0191] The means may also be configured to perform: disconnecting from the serving cell; and synchronizing with the selected target cell.

[0192] The at least one of the one or more handover configurations may also include an indication of one or more measurements to be performed.

[0193] The means may also be configured to perform: at least one of the one or more measurements; and selecting the target cell at least in part based on the result of the at least one measurement performed.

[0194] The means configured to perform selecting the target cell may include means configured to perform the following: selecting the target cell at least in part based on at least one of the following: predetermined information associated with the target cell located at the device; or the information for target cell selection, which may include at least one of a transmission configuration indicator status associated with the serving cell or the target cell, a reference signal received power value associated with the serving cell or the target cell, a downlink beam of the serving cell or the target cell, or a selection criterion.

[0195] The example device may be in a radio resource control connected state.

[0196] The indication of activation of the energy saving mode at the serving cell may include an indication of at least one of the following: cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0197] The indication of the one or more candidate target cells may be at least partially based on one or more network shutdown policies of the serving cell, one or more shutdown frequency layers of the serving cell, the shutdown order of the one or more shutdown frequency layers of the serving cell, or at least one of the frequency layers that belong to the same power saving group as at least one of the one or more shutdown frequency layers of the serving cell.

[0198] The apparatus may also be configured to perform: select an energy saving condition handover configuration from the one or more handover configurations at least partially based on the indication of the activation of the energy saving mode at the serving cell, wherein the selection of the target cell may also be based on the selected energy saving condition handover configuration.

[0199] The apparatus may also be configured to perform: receive an indication of when the one or more handover configurations will be applied, wherein the indication may include at least one of the following: the indication of the activation of the energy saving mode at the serving cell; a network offloading indication; an indication of the activation of the one or more handover configurations; or an indication of the time to enforce the one or more handover configurations, which may include at least one of a system frame number, a superframe number, or a number of time units.

[0200] The network offloading indication or the indication of the activation of the one or more handover configurations may include one of downlink control information or a media access control control element.

[0201] According to one example embodiment, a non-transitory computer-readable medium includes program instructions stored thereon that, when executed by at least one processor, cause the at least one processor to: cause to receive one or more handover configurations from a serving cell, wherein the one or more handover configurations may include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; cause to receive an indication of the activation of the energy saving mode at the serving cell; and select a target cell from the one or more candidate target cells at least partially based on the one or more handover configurations and the received indication of the activation of the energy saving mode at the serving cell.

[0202] The indication of the activation of the energy saving mode may be included in a broadcast message.

[0203] The example non-transitory computer-readable medium may also be configured to: cause to disconnect from the serving cell; and cause to synchronize with the selected target cell.

[0204] At least one of the one or more handover configurations may further include an indication of one or more measurements to be performed.

[0205] The example non-transitory computer-readable medium may also be configured to: cause at least one of the one or more measurements to be performed; and select the target cell at least in part based on the result of the at least one measurement that has been performed.

[0206] Selecting the target cell may include the example non-transitory computer-readable medium being further configured to: select the target cell at least in part based on one of the following: predetermined information associated with the target cell located at the non-transitory computer-readable medium, or the information for target cell selection, which may include at least one of the following: a transmission configuration indicator state associated with the serving cell or the target cell, a reference signal received power value associated with the serving cell or the target cell, a downlink beam of the serving cell or the target cell, or a selection criterion.

[0207] The indication of activation of the energy saving mode at the serving cell may include an indication of at least one of the following: cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0208] The indication of the one or more candidate target cells may be at least in part based on at least one of one or more network shutdown policies of the serving cell, one or more frequency layers that have been shut down of the serving cell, the shutdown order of the one or more frequency layers that have been shut down of the serving cell, or a frequency layer that belongs to the same power saving group as at least one of the one or more frequency layers that have been shut down of the serving cell.

[0209] The example non-transitory computer-readable medium may also be configured to: select an energy saving condition handover configuration among the one or more handover configurations at least in part based on the indication of activation of the energy saving mode at the serving cell, wherein selecting the target cell may also be based on the selected energy saving condition handover configuration.

[0210] The example non-transitory computer-readable medium may also be configured to: cause an indication of when the one or more handover configurations will be applied to be received, wherein the indication may include at least one of the following: the indication of activation of the energy saving mode at the serving cell; a network offloading indication; an indication of activation of the one or more handover configurations; or an indication of the time to enforce the one or more handover configurations, which may include at least one of a system frame number, a hyperframe number, or a number of time units.

[0211] The indication activated by the network offloading indication or the one or more handover configurations may include one of downlink control information or a media access control control element.

[0212] According to another example implementation, a machine-readable non-transitory program storage device may be provided, which tangibly embodies a program containing instructions executable by the machine to perform operations, the operations including: causing reception of one or more handover configurations from a serving cell, where the one or more handover configurations may include an energy-saving condition handover configuration, and where at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; causing reception of an indication of activation of an energy-saving mode at the serving cell; and selecting a target cell from the one or more candidate target cells at least partially based on the one or more handover configurations and the received indication of activation of the energy-saving mode at the serving cell.

[0213] According to one example implementation, a device may include: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the device to at least: determine activation of an energy-saving mode; generate one or more handover configurations, where the one or more handover configurations may include an energy-saving condition handover configuration, and where at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; transmit the one or more handover configurations to a user equipment; start activating the energy-saving mode; and transmit an indication of activation of the energy-saving mode to the user equipment.

[0214] The indication of activation of the energy-saving mode may be included in a broadcast message.

[0215] The example device may also be configured to: transmit a corresponding energy-saving condition handover information request to at least one of the one or more candidate target cells, where the corresponding energy-saving condition handover information request may include an energy-saving mode trigger; and receive a handover request response from the at least one candidate target cell.

[0216] The example device may also be configured to: transmit a corresponding cell deactivation indication to at least one of the one or more candidate target cells, where the corresponding cell deactivation indication may include at least one of an energy-saving condition handover information request, information on handover preparation for conditional handover, or a list of currently active user equipments to be offloaded to the corresponding candidate target cell among the one or more candidate target cells; and receive a handover request response from the one or more candidate target cells.

[0217] At least one of the one or more handover configurations may further include an indication of one or more measurements to be performed.

[0218] The example device may also be configured to: receive an indication of the result of at least one of the one or more measurements from the user equipment; determine a confidence level at which a target cell will be selected for synchronization at the user equipment based at least in part on the indication of the result of the at least one of the one or more measurements; compare the determined confidence level with a threshold; based on a determination that the determined confidence level is greater than the threshold, indicate to the user equipment to omit the execution of the one or more measurements and perform target cell selection based on at least one of: predetermined information associated with the target cell, or the information for target cell selection; and based on a determination that the determined confidence level is less than or equal to the threshold, indicate to the user equipment to perform target cell selection based on the execution of the one or more measurements.

[0219] The information for target cell selection may include at least one of a transmission configuration indicator state associated with the device or the target cell, a reference signal received power value associated with the device or the target cell, a downlink beam of the device or the target cell, or a selection criterion.

[0220] The power saving mode may include at least one of cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0221] The indication of the one or more candidate target cells may be at least partially based on at least one of one or more network shutdown policies, one or more frequency layers that have been shut down, the shutdown order of the one or more frequency layers that have been shut down, or a frequency layer that belongs to the same power saving group as at least one of the one or more frequency layers that have been shut down.

[0222] The example device may also be configured to: transmit an indication of when the one or more handover configurations will be applied to the user equipment, where the indication may include at least one of: an indication of the activation of the power saving mode; a network offloading indication; an indication of the activation of the one or more handover configurations; or an indication of the time to enforce the one or more handover configurations, which may include at least one of a system frame number, a superframe number, or a number of time units.

[0223] The network offloading indication or the indication of the activation of the one or more handover configurations may include one of downlink control information or a media access control control element.

[0224] According to one aspect, an example method may be provided, which includes: determining to activate an energy saving mode; generating one or more handover configurations, wherein the one or more handover configurations may include an energy saving condition handover configuration, and at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; transmitting the one or more handover configurations to a user equipment; starting to activate the energy saving mode; and transmitting an indication of the activation of the energy saving mode to the user equipment.

[0225] The indication of the activation of the energy saving mode may be included in a broadcast message.

[0226] The example method may further include: transmitting a corresponding energy saving condition handover information request to at least one of the one or more candidate target cells, wherein the corresponding energy saving condition handover information request may include an energy saving mode trigger; and receiving a handover request response from the at least one candidate target cell.

[0227] The example method may further include: transmitting a corresponding cell deactivation indication to at least one of the one or more candidate target cells, wherein the corresponding cell deactivation indication may include at least one of an energy saving condition handover information request, information on handover preparation for conditional handover, or a list of current active user equipments to be offloaded to the corresponding candidate target cell among the one or more candidate target cells; and receiving a handover request response from the one or more candidate target cells.

[0228] At least one of the one or more handover configurations may further include an indication of one or more measurements to be performed.

[0229] The example method may further include: receiving an indication of the result of at least one of the one or more measurements from the user equipment; determining, at least in part based on the indication of the result of the at least one of the one or more measurements, a confidence level at which a target cell will be selected for synchronization at the user equipment among the one or more candidate target cells; comparing the determined confidence level with a threshold; based on a determination that the determined confidence level is greater than the threshold, indicating to the user equipment to omit the execution of the one or more measurements and perform target cell selection based on at least one of the predetermined information associated with the target cell or the information for target cell selection; and based on a determination that the determined confidence level is less than or equal to the threshold, indicating to the user equipment to perform target cell selection based on the execution of the one or more measurements.

[0230] The information for target cell selection may include at least one of a transmission configuration indicator status associated with a base station or a target cell, a reference signal received power value associated with the base station or the target cell, a downlink beam of the base station or the target cell, or a selection criterion.

[0231] The power saving mode may include at least one of cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0232] The indication of the one or more candidate target cells may be at least partially based on at least one of one or more network shutdown policies, one or more frequency layers that have been shut down, a shutdown order of the one or more frequency layers that have been shut down, or a frequency layer that belongs to the same power saving group as at least one of the one or more frequency layers that have been shut down.

[0233] The example method may further include: transmitting an indication of when the one or more handover configurations will be applied to the user equipment, where the indication may include at least one of the following: the indication of the activation of the power saving mode; a network offloading indication; an indication of the activation of the one or more handover configurations; or an indication of a time to enforce the one or more handover configurations, which may include at least one of a system frame number, a superframe number, or a number of time units.

[0234] The network offloading indication or the indication of the activation of the one or more handover configurations may include one of downlink control information or a media access control control element.

[0235] According to one example implementation, an apparatus may include: circuitry configured to perform the following: determine to activate a power saving mode; generate one or more handover configurations, where the one or more handover configurations may include a power saving condition handover configuration, and where at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; transmit the one or more handover configurations to a user equipment; start activating the power saving mode; and transmit an indication of the activation of the power saving mode to the user equipment.

[0236] According to an example implementation, a device may include: processing circuitry; a memory circuitry including computer program code, the memory circuitry and the computer program code being configured to, together with the processing circuitry, enable the device to: determine to activate an energy saving mode; generate one or more handover configurations, wherein the one or more handover configurations may include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; transmit the one or more handover configurations to a user equipment; initiate activation of the energy saving mode; and transmit an indication of activation of the energy saving mode to the user equipment.

[0237] According to an example implementation, a device may include means for performing the following: determining to activate an energy saving mode; generating one or more handover configurations, wherein the one or more handover configurations may include an energy saving condition handover configuration, and wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; transmitting the one or more handover configurations to a user equipment; initiating activation of the energy saving mode; and transmitting an indication of activation of the energy saving mode to the user equipment.

[0238] The indication of activation of the energy saving mode may be included in a broadcast message.

[0239] The means may also be configured to perform: transmitting a respective energy saving condition handover information request to at least one of the one or more candidate target cells, wherein the respective energy saving condition handover information request may include an energy saving mode trigger; and receiving a handover request response from the at least one candidate target cell.

[0240] The means may also be configured to perform: transmitting a respective cell deactivation indication to at least one of the one or more candidate target cells, wherein the respective cell deactivation indication may include at least one of an energy saving condition handover information request, information on handover preparation for conditional handover, or a list of currently active user equipments to be offloaded to a respective candidate target cell among the one or more candidate target cells; and receiving a handover request response from the one or more candidate target cells.

[0241] At least one of the one or more handover configurations may further include an indication of one or more measurements to be performed.

[0242] The apparatus may also be configured to perform: receiving an indication of a result of at least one of the one or more measurements from the user equipment; determining, at least in part based on the indication of the result of the at least one of the one or more measurements, a confidence level at which a target cell among the one or more candidate target cells will be selected for synchronization at the user equipment; comparing the determined confidence level with a threshold; based on a determination that the determined confidence level is greater than the threshold, instructing the user equipment to: omit execution of the one or more measurements and perform target cell selection based on at least one of predetermined information associated with the target cell or the information for target cell selection; and based on a determination that the determined confidence level is less than or equal to the threshold, instructing the user equipment to perform target cell selection based on execution of the one or more measurements.

[0243] The information for target cell selection may include at least one of a transmission configuration indicator state associated with the device or the target cell, a reference signal received power value associated with the device or the target cell, a downlink beam of the device or the target cell, or a selection criterion.

[0244] The power saving mode may include at least one of cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0245] The indication of the one or more candidate target cells may be at least in part based on at least one of one or more network shutdown policies, one or more frequency layers that have been shut down, a shutdown order of the one or more frequency layers that have been shut down, or a frequency layer that belongs to the same power saving group as at least one of the one or more frequency layers that have been shut down.

[0246] The apparatus may also be configured to perform: transmitting an indication to the user equipment of when the one or more handover configurations will be applied, where the indication may include at least one of the following: an indication of activation of the power saving mode; a network offloading indication; an indication of activation of the one or more handover configurations; or an indication of a time to enforce the one or more handover configurations, which may include at least one of a system frame number, a hyperframe number, or a number of time units.

[0247] The network offloading indication or the indication of activation of the one or more handover configurations may include one of downlink control information or a media access control control element.

[0248] According to an example implementation, a non-transitory computer-readable medium includes program instructions stored thereon, which when executed by at least one processor cause the at least one processor to: determine to activate an energy-saving mode; generate one or more handover configurations, wherein the one or more handover configurations may include an energy-saving condition handover configuration, and at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; cause the one or more handover configurations to be transmitted to a user equipment; start activating the energy-saving mode; and cause an indication of the activation of the energy-saving mode to be transmitted to the user equipment.

[0249] The indication of the activation of the energy-saving mode may be included in a broadcast message.

[0250] The example non-transitory computer-readable medium may also be configured to: cause a corresponding energy-saving condition handover information request to be transmitted to at least one of the one or more candidate target cells, wherein the corresponding energy-saving condition handover information request may include an energy-saving mode trigger; and cause a handover request response to be received from the at least one candidate target cell.

[0251] The example non-transitory computer-readable medium may also be configured to: cause a corresponding cell deactivation indication to be transmitted to at least one of the one or more candidate target cells, wherein the corresponding cell deactivation indication may include at least one of an energy-saving condition handover information request, information on handover preparation for conditional handover, or a list of currently active user equipments to be offloaded to the corresponding candidate target cell among the one or more candidate target cells; and cause a handover request response to be received from the one or more candidate target cells.

[0252] At least one of the one or more handover configurations may also include an indication of one or more measurements to be performed.

[0253] The example non-transitory computer-readable medium may also be configured to: cause an indication of a result of at least one of the one or more measurements to be received from the user equipment; determine, at least in part based on the indication of the result of the at least one of the one or more measurements, a confidence level that a target cell will be selected from the one or more candidate target cells for synchronization at the user equipment; compare the determined confidence level with a threshold; based on a determination that the determined confidence level is greater than the threshold, cause an indication to be sent to the user equipment to omit execution of the one or more measurements and perform target cell selection based on at least one of predetermined information associated with the target cell or the information for target cell selection; and based on a determination that the determined confidence level is less than or equal to the threshold, cause an indication to be sent to the user equipment to perform target cell selection based on execution of the one or more measurements.

[0254] The information for target cell selection may include at least one of a transmission configuration indicator state associated with a base station or a target cell, a reference signal received power value associated with the base station or the target cell, a downlink beam of the base station or the target cell, or a selection criterion.

[0255] The power saving mode may include at least one of cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

[0256] The indication of the one or more candidate target cells may be at least in part based on at least one of one or more network shutdown policies, one or more frequency layers that have been shut down, a shutdown order of the one or more frequency layers that have been shut down, or frequency layers that belong to the same power saving group as at least one of the one or more frequency layers that have been shut down.

[0257] The example non-transitory computer-readable medium may also be configured to: cause an indication of when the one or more handover configurations will be applied to be transmitted to the user equipment, where the indication may include at least one of the following: an indication of activation of the power saving mode; a network offloading indication; an indication of activation of the one or more handover configurations; or an indication of a time to enforce the one or more handover configurations, which may include at least one of a system frame number, a hyperframe number, or a number of time units.

[0258] The network offloading indication or the indication of activation of the one or more handover configurations may include one of downlink control information or a media access control control element.

[0259] According to another example implementation, a machine-readable non-transitory program storage device may be provided that tangibly embodies a program including instructions executable by the machine to perform operations, the operations including: determining to activate an energy-saving mode; generating one or more handover configurations, wherein the one or more handover configurations may include an energy-saving condition handover configuration, and wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; causing the one or more handover configurations to be transmitted to a user equipment; starting to activate the energy-saving mode; and causing an indication of the activation of the energy-saving mode to be transmitted to the user equipment.

[0260] According to another example implementation, a computer program may include instructions stored thereon for at least performing the following: receiving one or more handover configurations from a serving cell, wherein the one or more handover configurations may include an energy-saving condition handover configuration, and wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; receiving an indication of the activation of the energy-saving mode at the serving cell from the serving cell; and selecting a target cell from the one or more candidate target cells at least in part based on the one or more handover configurations and the received indication of the activation of the energy-saving mode at the serving cell.

[0261] According to another example implementation, a computer program may include instructions stored thereon for at least performing the following: determining to activate an energy-saving mode; generating one or more handover configurations, wherein the one or more handover configurations may include an energy-saving condition handover configuration, and wherein at least one of the one or more handover configurations may include at least one of an indication of one or more candidate target cells or information for target cell selection; transmitting the one or more handover configurations to a user equipment; starting to activate the energy-saving mode; and transmitting an indication of the activation of the energy-saving mode to the user equipment.

[0262] It should be understood that the above description is illustrative only. Various alternatives and modifications can be conceived by those skilled in the art. For example, the features described in the dependent claims can be combined with each other in any suitable combination. Additionally, features from the different implementations above can be selectively combined into new implementations. Therefore, this specification is intended to cover all such alternatives, modifications, and variations that fall within the scope of the appended claims.

Claims

1. An apparatus, comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least: receive a conditional handover configuration from a serving cell, wherein the conditional handover configuration is associated with an energy saving mode, and wherein the conditional handover configuration includes: an indication of one or more candidate target cells, and information for target cell selection; after receiving the conditional handover configuration, receive an indication of activation of the energy saving mode at the serving cell; and conditionally, upon receiving the indication of activation of the energy saving mode at the serving cell, select a target cell for handover from the one or more candidate target cells based on the information for target cell selection included in the conditional handover configuration.

2. The apparatus according to claim 1, wherein the information for target cell selection includes one or more execution conditions, and wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: evaluate the one or more execution conditions and select the target cell from the one or more candidate target cells based on the evaluation of the one or more execution conditions.

3. The apparatus according to claim 1, wherein the information for target cell selection includes one or more radio conditions to be evaluated.

4. The apparatus according to any one of claims 1 to 3, wherein the indication of activation of the energy saving mode is included in a broadcast message.

5. The apparatus according to any one of claims 1 to 4, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: disconnect from the serving cell; and synchronize with the selected target cell.

6. The apparatus according to any one of claims 1 to 5, wherein the conditional handover configuration further includes an indication of one or more measurements to be performed.

7. The apparatus according to claim 6, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: perform at least one of the one or more measurements; and select the target cell at least in part based on the result of the at least one measurement performed.

8. The apparatus according to any one of claims 1 to 7, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: select the target cell at least in part based on one of the following: predetermined information associated with the target cell located at the apparatus, or the information for target cell selection, which includes at least one of the following: a transmission configuration indicator status associated with the serving cell or the target cell, a reference signal received power value associated with the serving cell or the target cell, a downlink beam of the serving cell or the target cell, or a selection criterion.

9. The apparatus according to any one of claims 1 to 8, wherein the apparatus is in a radio resource control connected state.

10. The apparatus according to any one of claims 1 to 9, wherein the indication of the activation of the energy saving mode at the serving cell comprises an indication of at least one of the following: cell shutdown, network transmit power reduction, or multi-input multi-output transmit antenna element muting.

11. The apparatus according to any one of claims 1 to 10, wherein the indication of the one or more candidate target cells is at least partially based on at least one of the following: one or more network shutdown policies of the serving cell, one or more frequency layers that have been shut down in the serving cell, the shutdown order of the one or more frequency layers that have been shut down in the serving cell, or frequency layers that belong to the same power saving group as at least one of the one or more frequency layers that have been shut down in the serving cell.

12. The apparatus according to any one of claims 1 to 11, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to: receive an indication of when the conditional handover configuration will be applied, wherein the indication comprises at least one of the following: the indication of the activation of the energy saving mode at the serving cell, a network offloading indication, an indication of the activation of the conditional handover configuration, or an indication of the time to enforce the conditional handover configuration, which comprises at least one of the following: a system frame number, a superframe number, or a number of time units.

13. The apparatus according to claim 12, wherein the network offloading indication or the indication of the activation of the conditional handover configuration comprises one of the following: downlink control information, or a media access control control element.

14. A method, comprising: receiving, by a user equipment, a conditional handover configuration from a serving cell, wherein the conditional handover configuration is associated with an energy saving mode, and wherein the conditional handover configuration comprises: an indication of one or more candidate target cells, and information for target cell selection; after receiving the conditional handover configuration, receiving, from the serving cell, an indication of the activation of the energy saving mode at the serving cell; and conditionally, when receiving the indication of the activation of the energy saving mode at the serving cell, selecting, based on the information for target cell selection included in the conditional handover configuration, a target cell for handover from the one or more candidate target cells.

15. The method according to claim 14, wherein the information for target cell selection comprises one or more execution conditions, and wherein the method further comprises: evaluating the one or more execution conditions and selecting the target cell from the one or more candidate target cells based on the evaluation of the one or more execution conditions.

16. The method according to claim 14, wherein the information for target cell selection comprises one or more radio conditions to be evaluated.

17. The method according to any one of claims 14 to 16, wherein the indication of the activation of the energy saving mode is included in a broadcast message.

18. The method according to any one of claims 14 to 17, further comprising: disconnecting the user equipment from the serving cell; and synchronizing the user equipment with the selected target cell.

19. The method according to any one of claims 14 to 18, wherein the conditional handover configuration further comprises an indication of one or more measurements to be performed.

20. The method according to claim 19, further comprising: performing at least one of the one or more measurements; and selecting the target cell at least in part based on the result of the at least one measurement performed.

21. The method according to any one of claims 14 to 20, wherein said selecting the target cell comprises: selecting the target cell at least in part based on one of the following: predetermined information associated with the target cell located at the user equipment, or the information for target cell selection, which comprises at least one of the following: a transmission configuration indicator status associated with the serving cell or the target cell, a reference signal received power value associated with the serving cell or the target cell, a downlink beam of the serving cell or the target cell, or a selection criterion.

22. The method according to any one of claims 14 to 21, wherein the user equipment is in a radio resource control connected state.

23. The method according to any one of claims 14 to 22, wherein the indication of the activation of the power saving mode at the serving cell comprises an indication of at least one of the following: cell shutdown, reduction of network transmission power, or silencing of multiple-input multiple-output transmission antenna elements.

24. The method according to any one of claims 14 to 23, wherein the indication of the one or more candidate target cells is at least in part based on at least one of the following: one or more network shutdown policies of the serving cell, one or more frequency layers that have been shut down in the serving cell, the shutdown sequence of the one or more frequency layers that have been shut down in the serving cell, or frequency layers that belong to the same power saving group as at least one of the one or more frequency layers that have been shut down in the serving cell.

25. The method according to any one of claims 14 to 24, further comprising: receiving an indication of when the conditional handover configuration will be applied, wherein the indication comprises at least one of the following: the indication of the activation of the power saving mode at the serving cell, a network offloading indication, an indication of the activation of the conditional handover configuration, or an indication of the time to enforce the conditional handover configuration, which comprises at least one of the following: a system frame number, a hyperframe number, or a number of time units.

26. The method according to claim 25, wherein the network offloading indication or the indication of the activation of the conditional handover configuration comprises one of the following: downlink control information, or a media access control control element.

27. A non - transitory computer - readable medium comprising instructions stored thereon, which when executed by at least one processor, cause the at least one processor to perform at least the following operations: Receive a conditional handover configuration from a serving cell, wherein the conditional handover configuration is associated with an energy - saving mode, and wherein the conditional handover configuration comprises: An indication of one or more candidate target cells, and Information for target cell selection; After receiving the conditional handover configuration, receive an indication of activation of the energy - saving mode at the serving cell; And Conditionally, when receiving the indication of activation of the energy - saving mode at the serving cell, select a target cell for handover from the one or more candidate target cells based on the information for target cell selection included in the conditional handover configuration.

28. The non - transitory computer - readable medium according to claim 27, wherein the information for target cell selection comprises one or more execution conditions, and wherein the non - transitory computer - readable medium further comprises instructions stored thereon, which when executed by the at least one processor, cause the at least one processor to perform at least the following operations: Evaluate the one or more execution conditions and select the target cell from the one or more candidate target cells based on the evaluation of the one or more execution conditions.

29. The non - transitory computer - readable medium according to claim 27, wherein the information for target cell selection comprises one or more radio conditions to be evaluated.

30. The non - transitory computer - readable medium according to any one of claims 27 to 29, wherein the indication of activation of the energy - saving mode is included in a broadcast message.

31. The non - transitory computer - readable medium according to any one of claims 27 to 30, further comprising instructions stored thereon, which when executed by the at least one processor, cause the at least one processor to perform at least the following operations: Disconnect from the serving cell; and Synchronize with the selected target cell.

32. The non - transitory computer - readable medium according to any one of claims 27 to 31, wherein the conditional handover configuration further comprises an indication of one or more measurements to be performed.

33. The non - transitory computer - readable medium according to claim 32, further comprising instructions stored thereon, which when executed by the at least one processor, cause the at least one processor to perform at least the following operations: Perform at least one of the one or more measurements; and Select the target cell at least in part based on the result of the at least one measurement performed.

34. The non - transitory computer - readable medium according to any one of claims 27 to 33, further comprising instructions stored thereon, which when executed by the at least one processor, cause the at least one processor to perform at least the following operations: Select the target cell at least in part based on one of the following: Predetermined information associated with the target cell located at the device, or The information for target cell selection includes at least one of the following: The transmission configuration indicator status associated with the serving cell or the target cell, The reference signal received power value associated with the serving cell or the target cell, The downlink beam of the serving cell or the target cell, or The selection criteria.

35. The non-transitory computer-readable medium according to any one of claims 27 to 34, wherein the device is in a radio resource control connected state.

36. The non-transitory computer-readable medium according to any one of claims 27 to 35, wherein the indication of the activation of the energy saving mode at the serving cell includes an indication of at least one of the following: Cell shutdown, Reduction of network transmission power, or Muting of multiple-input multiple-output transmit antenna elements.

37. The non-transitory computer-readable medium according to any one of claims 27 to 36, wherein the indication of the one or more candidate target cells is at least partially based on at least one of the following: One or more network shutdown policies of the serving cell, One or more frequency layers that have been shut down in the serving cell, The shutdown order of the one or more frequency layers that have been shut down in the serving cell, or Frequency layers that belong to the same power saving group as at least one of the one or more frequency layers that have been shut down in the serving cell.

38. The non-transitory computer-readable medium according to any one of claims 27 to 37, further comprising instructions stored thereon that, when executed by the at least one processor, cause the at least one processor to at least perform the following operations: Receive an indication of when the conditional handover configuration will be applied, wherein the indication includes at least one of the following: The indication of the activation of the energy saving mode at the serving cell, A network offloading indication, An indication of the activation of the conditional handover configuration, or An indication of the time to enforce the conditional handover configuration, which includes at least one of the following: System frame number, Hyperframe number, or Number of time units.

39. The non-transitory computer-readable medium according to claim 38, wherein the network offloading indication or the indication of the activation of the conditional handover configuration includes one of the following: Downlink control information, or Medium access control control element.

40. A device, comprising: At least one processor; And At least one memory including computer program code; The at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least: Determine to activate the energy saving mode; Generate a conditional handover configuration, wherein the conditional handover configuration is associated with the energy saving mode, and wherein the conditional handover configuration includes: An indication of one or more candidate target cells, and Information for target cell selection; Transmit the conditional handover configuration to the user equipment; After transmitting the conditional handover configuration, start activating the energy saving mode; and Transmit an indication of the activation of the energy saving mode to the user equipment.

41. The apparatus according to claim 40, wherein the information for target cell selection includes one or more execution conditions.

42. The apparatus according to claim 40, wherein the information for target cell selection includes one or more radio conditions to be evaluated.

43. The apparatus according to any one of claims 40 to 42, wherein the indication of activation of the energy saving mode is included in a broadcast message.

44. The apparatus according to any one of claims 40 to 43, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus: Transmit a corresponding energy saving condition handover information request to at least one of the one or more candidate target cells, wherein the corresponding energy saving condition handover information request includes an energy saving mode trigger; and Receive a handover request response from the at least one candidate target cell.

45. The apparatus according to any one of claims 40 to 44, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus: Transmit a corresponding cell deactivation indication to at least one of the one or more candidate target cells, wherein the corresponding cell deactivation indication includes at least one of the following: An energy saving condition handover information request, Information on handover preparation for condition handover, or A list of currently active user equipments to be offloaded to the corresponding candidate target cell among the one or more candidate target cells; and Receive a handover request response from the one or more candidate target cells.

46. The apparatus according to any one of claims 40 to 45, wherein the condition handover configuration further includes an indication of one or more measurements to be performed.

47. The apparatus according to claim 46, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus: Receive an indication of the result of at least one of the one or more measurements from the user equipment; Determine, at least in part based on the indication of the result of the at least one of the one or more measurements, the confidence level for selecting a target cell among the one or more candidate target cells for synchronization at the user equipment; Compare the determined confidence level with a threshold; Based on a determination that the determined confidence level is greater than the threshold, instruct the user equipment to: omit the execution of the one or more measurements, and perform target cell selection based on at least one of the following: Predetermined information associated with the target cell, or The information for target cell selection; and Based on a determination that the determined confidence level is less than or equal to the threshold, instruct the user equipment to perform target cell selection based on the execution of the one or more measurements.

48. The apparatus according to any one of claims 40 to 47, wherein the information for target cell selection includes at least one of the following: A transmission configuration indicator status associated with the apparatus or the target cell, A reference signal reception power value associated with the device or the target cell, a downlink beam of the device or the target cell, or a selection criterion.

49. The device according to any one of claims 40 to 48, wherein the energy saving mode comprises at least one of the following: cell shutdown, a reduction in network transmit power, or mute of multiple-input multiple-output transmit antenna elements.

50. The device according to any one of claims 40 to 49, wherein the indication of the one or more candidate target cells is at least partially based on at least one of the following: one or more network shutdown policies, one or more frequency layers that have been shut down, the shutdown order of the one or more frequency layers that have been shut down, or frequency layers that belong to the same power saving group as at least one of the one or more frequency layers that have been shut down.

51. The device according to any one of claims 40 to 50, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to: transmit an indication of when the conditional handover configuration will be applied to the user equipment, wherein the indication comprises at least one of the following: the indication of the activation of the energy saving mode, a network offloading indication, the indication of the activation of the conditional handover configuration, or an indication of the time to enforce the conditional handover configuration, which comprises at least one of the following: a system frame number, a superframe number, or a number of time units.

52. The device according to claim 51, wherein the network offloading indication or the indication of the activation of the conditional handover configuration comprises one of the following: downlink control information, or a media access control control element.

53. A method, comprising: determining to activate an energy saving mode; generating a conditional handover configuration, wherein the conditional handover configuration is associated with the energy saving mode, and wherein the conditional handover configuration comprises: an indication of one or more candidate target cells, and information for target cell selection; transmitting the conditional handover configuration to a user equipment; after transmitting the conditional handover configuration, starting to activate the energy saving mode; and transmitting an indication of the activation of the energy saving mode to the user equipment.

54. The method according to claim 53, wherein the information for target cell selection comprises one or more execution conditions.

55. The method according to claim 53, wherein the information for target cell selection comprises one or more radio conditions to be evaluated.

56. The method according to any one of claims 53 to 55, wherein the indication of the activation of the energy saving mode is included in a broadcast message.

57. The method according to any one of claims 53 to 56, further comprising: transmitting a corresponding energy saving conditional handover information request to at least one of the one or more candidate target cells, wherein the corresponding energy saving conditional handover information request comprises an energy saving mode trigger; and receiving a handover request response from the at least one candidate target cell.

58. The method according to any one of claims 53 to 57, further comprising: Transmit a corresponding cell deactivation indication to at least one of the one or more candidate target cells, where the corresponding cell deactivation indication includes at least one of the following: An energy saving condition handover information request, Information on handover preparation for conditional handover, or A list of currently active user equipment to be offloaded to the corresponding candidate target cell among the one or more candidate target cells; And Receive a handover request response from the one or more candidate target cells.

59. The method according to any one of claims 53 to 58, wherein the conditional handover configuration further includes an indication of one or more measurements to be performed.

60. The method according to claim 59, further comprising: Receive an indication of the result of at least one of the one or more measurements from the user equipment; Determine a confidence level for synchronizing to a target cell among the one or more candidate target cells to be selected at the user equipment based at least in part on the indication of the result of the at least one of the one or more measurements; Compare the determined confidence level with a threshold; Based on a determination that the determined confidence level is greater than the threshold, instruct the user equipment to: omit execution of the one or more measurements, and perform target cell selection based on at least one of the following: Predetermined information associated with the target cell, or The information for target cell selection; and Based on a determination that the determined confidence level is less than or equal to the threshold, instruct the user equipment to perform target cell selection based on execution of the one or more measurements.

61. The method according to any one of claims 53 to 60, wherein the information for target cell selection includes at least one of the following: A transmission configuration indicator state associated with the device or the target cell, A reference signal received power value associated with the device or the target cell, A downlink beam of the device or the target cell, or A selection criterion.

62. The method according to any one of claims 53 to 61, wherein the energy saving mode includes at least one of the following: Cell shutdown, Reduction of network transmit power, or Silencing of multiple-input multiple-output transmit antenna elements.

63. The method according to any one of claims 53 to 62, wherein the indication of the one or more candidate target cells is at least partially based on at least one of the following: One or more network shutdown policies, One or more frequency layers that have been shut down, The shutdown order of the one or more frequency layers that have been shut down, or Frequency layers that belong to the same power saving group as at least one of the one or more frequency layers that have been shut down.

64. The method according to any one of claims 53 to 62, further comprising: Transmit an indication of when the conditional handover configuration will be applied to the user equipment, where the indication includes at least one of the following: The indication of activation of the energy saving mode, A network offloading indication, The indication of activation of the conditional handover configuration, or An indication of the time to enforce the conditional handover configuration, comprising at least one of the following: System frame number, Super high frame number, or Number of time units.

65. The method according to claim 64, wherein the indication of the network offload indication or the activation of the conditional handover configuration comprises one of the following: Downlink control information, or Media access control control element.

66. A non-transitory computer-readable medium comprising instructions stored thereon that, when executed by at least one processor, cause the at least one processor to perform at least the following operations: Determine to activate an energy saving mode; Generate a conditional handover configuration, wherein the conditional handover configuration is associated with the energy saving mode, and wherein the conditional handover configuration comprises: An indication of one or more candidate target cells, and Information for target cell selection; Transmit the conditional handover configuration to a user equipment; After transmitting the conditional handover configuration, start activating the energy saving mode; and Transmit an indication of the activation of the energy saving mode to the user equipment.

67. The non-transitory computer-readable medium according to claim 66, wherein the information for target cell selection comprises one or more execution conditions.

68. The non-transitory computer-readable medium according to claim 66, wherein the information for target cell selection comprises one or more radio conditions to be evaluated.

69. The non-transitory computer-readable medium according to any one of claims 66 to 68, wherein the indication of the activation of the energy saving mode is included in a broadcast message.

70. The non-transitory computer-readable medium according to any one of claims 66 to 69, further comprising instructions stored thereon that, when executed by the at least one processor, cause the at least one processor to perform at least the following operations: Transmit a corresponding energy saving conditional handover information request to at least one of the one or more candidate target cells, wherein the corresponding energy saving conditional handover information request comprises an energy saving mode trigger; and Receive a handover request response from the at least one candidate target cell.

71. The non-transitory computer-readable medium according to any one of claims 66 to 70, further comprising instructions stored thereon that, when executed by the at least one processor, cause the at least one processor to perform at least the following operations: Transmit a corresponding cell deactivation indication to at least one of the one or more candidate target cells, wherein the corresponding cell deactivation indication comprises at least one of the following: Energy saving conditional handover information request, Information about handover preparation for conditional handover, or A list of currently active user equipments to be offloaded to the corresponding candidate target cell among the one or more candidate target cells; and Receive a handover request response from the one or more candidate target cells.

72. The non-transitory computer-readable medium according to any one of claims 66 to 71, wherein the conditional handover configuration further comprises an indication of one or more measurements to be performed.

73. The non-transitory computer-readable medium according to claim 72, further comprising instructions stored thereon that, when executed by the at least one processor, cause the at least one processor to at least perform the following operations: Receive an indication of the result of at least one of the one or more measurements from the user equipment; Determine, at least in part based on the indication of the result of the at least one of the one or more measurements, a confidence level for synchronizing to a target cell selected from the one or more candidate target cells at the user equipment; Compare the determined confidence level with a threshold; Based on a determination that the determined confidence level is greater than the threshold, instruct the user equipment to: omit execution of the one or more measurements and perform target cell selection based on at least one of the following: Predetermined information associated with the target cell, or The information for target cell selection; and Based on a determination that the determined confidence level is less than or equal to the threshold, instruct the user equipment to perform target cell selection based on execution of the one or more measurements.

74. The non-transitory computer-readable medium according to any one of claims 66 to 73, wherein the information for target cell selection comprises at least one of the following: A transmission configuration indicator status associated with the device or the target cell, A reference signal received power value associated with the device or the target cell, A downlink beam of the device or the target cell, or A selection criterion.

75. The non-transitory computer-readable medium according to any one of claims 66 to 74, wherein the power saving mode comprises at least one of the following: Cell shutdown, Reduction of network transmit power, or Silencing of multiple-input multiple-output transmit antenna elements.

76. The non-transitory computer-readable medium according to any one of claims 66 to 75, wherein the indication of the one or more candidate target cells is at least in part based on at least one of the following: One or more network shutdown policies, One or more frequency layers that have been shut down, The shutdown order of the one or more frequency layers that have been shut down, or Frequency layers that belong to the same power saving group as at least one of the one or more frequency layers that have been shut down.

77. The non-transitory computer-readable medium according to any one of claims 66 to 76, further comprising instructions stored thereon that, when executed by the at least one processor, cause the at least one processor to at least perform the following operations: Transmit an indication of when the conditional handover configuration will be applied to the user equipment, wherein the indication comprises at least one of the following: The indication of activation of the power saving mode, A network offloading indication, The indication of activation of the conditional handover configuration, or An indication of the time to enforce the conditional handover configuration, which comprises at least one of the following: A system frame number, An ultra-high frame number, or A number of time units.

78. The non-transitory computer-readable medium of claim 77, wherein the indication of the network offload indication or activation of the conditional handover configuration comprises one of the following: downlink control information, or media access control control element.

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