Mobility in wireless communication system

Abstract

The present application relates to a network node for providing radio coverage to a user equipment configured to support carrier aggregation and dual connectivity. Carrier aggregation provides at least a first serving frequency serving the primary cell and at least one further serving frequency serving the at least one secondary cell. The network node is configured to determine a potential candidate cell for addition to a primary secondary cell during a handover of the user equipment to the network node with a group of secondary cells. The potential candidate cells include cells whose operating frequencies are not one of the service frequencies; and the network generates and transmits an indication of the non-serving operating frequency to the serving network node to allow the serving network to request the user equipment to perform measurements for appropriate primary and secondary cell candidates.

Description

Technical Field

[0001] Various example embodiments relate to wireless communication systems, and more specifically, to facilitating mobility within such wireless communication systems. Background Technology

[0002] When a User Equipment (UE) moves within a wireless communication system, it can move within a cell that includes a radio coverage area supported by one or more network access nodes. The ability of a UE to maintain effective communication with the wireless communication system while moving within the radio coverage area is commonly referred to as mobility. For UEs configured to use carrier aggregation and support dual connectivity, complexity may be added, enabling the UE to simultaneously connect to a primary cell and a secondary cell, with the secondary cell increasing the UE's throughput. Handover within the primary cell may affect the configuration of connections to the secondary cell. Summary of the Invention

[0003] The scope of protection sought by the various exemplary embodiments of the present invention is set forth in the independent claims. Exemplary embodiments and features (if any) described herein that do not fall within the scope of the independent claims should be interpreted as examples that aid in understanding the various embodiments of the invention.

[0004] According to various (but not necessarily all) exemplary embodiments of the present invention, a network node is provided for supporting the provision of radio coverage to a user equipment, the user equipment being configured to support carrier aggregation and dual connectivity, the carrier aggregation including at least a first serving frequency of a serving primary cell and at least one additional serving frequency of at least one serving secondary cell, the network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network node to at least: determine at least one cell, the at least one cell being added as a potential candidate cell for primary and secondary cells during a handover of the user equipment from the serving network node to the network node having a group of secondary cells and when the operating frequency of the at least one cell differs from the serving frequency of the serving primary cell and any serving secondary cell for the user equipment; and generate an indication of the operating frequency of the at least one potential candidate cell for transmission to the serving network node.

[0005] During handover with secondary cell groups, measurements transmitted by the user equipment (UE) are used to select the cell for handover. Traditionally, the measurements transmitted by the UE in its measurement reports that aid in selecting preferred primary and secondary cells are limited to measurements of the best neighboring cells operating on the same frequencies as each serving secondary cell. This limits the range of potential primary and secondary cells that can be selected during handover. It has been recognized that non-serving network nodes are aware of some neighboring cells that could potentially become primary and secondary cells. However, such cells may not operate on one of the serving frequencies of the current secondary cell and would therefore be excluded as primary and secondary cells during handover or cell change, as the UE would not perform measurements for these cells and thus would not provide information to the serving cell. The above problem can be solved by having the network node identify cells as candidate primary and secondary cells and, when such cells operate on frequencies or have radio coverage that do not belong to one of the serving frequencies of the serving primary or secondary cell, transmitting an indication of that frequency to the serving network node.

[0006] In this way, various embodiments attempt to increase the selection of primary and secondary cells by instructing the user equipment to perform additional measurements, making it possible to consider and potentially add potential candidate primary and secondary cells during any handover, which improves the throughput of the user equipment.

[0007] Handover may include cell change and / or cell handover. Various embodiments of the process allow a UE to change / handover from a serving cell to a neighboring cell / candidate cell / target cell while maintaining communication via the cellular / radio network to the global communication network.

[0008] In some example embodiments, the measurements performed by the user equipment may include at least one of the following: layer-1 signal strength measurement or layer-1 signal quality measurement.

[0009] A secondary cell can be a cell whose radio coverage is located within the radio coverage of the corresponding primary cell. A secondary serving cell is a cell controlled by the same network node as the primary serving cell, but provides radio coverage in a different serving frequency.

[0010] In some example implementations, this measurement is used to enable the serving primary node of the serving primary cell to initiate conditional handover with secondary cell groups.

[0011] In some example embodiments, network nodes are configured to determine which of at least one potential primary / secondary cell is the preferred candidate cell, and generate frequency indications only for the preferred primary / secondary cell.

[0012] In situations where there are many potential candidate primary and secondary cells, it may be advantageous for network nodes to select a cell or subset that is likely to become the preferred cell during handover, and to indicate only the frequency of these cells.

[0013] In some example embodiments, a network node is configured to determine which of at least one potential primary / secondary cell is the preferred primary / secondary cell in response to a message received from at least one of the Operations Management and Maintenance (OAM) messages, or a message generated by the self-organizing network (SON) module or machine learning / artificial intelligence (AI / ML) module associated with the network.

[0014] In some example implementations, messages received from OAM, SON, AI / ML include indications of multiple potential candidate primary and secondary cells that may provide preferred coverage for user equipment.

[0015] In some example embodiments, the indication of preferred candidate primary and secondary cells is based on location, mobility, and / or configuration.

[0016] A cell that may be selected as a preferred primary or secondary cell depends on several factors, including at least one of the following: the location of the cell, the location of the UE, the mobility of the UE and / or the configuration of the UE and / or the cell.

[0017] In some example embodiments, network nodes are also configured to transmit an indication of frequency to the serving network node as a switching information element.

[0018] In some example embodiments, the frequency indication is sent via an interface between network nodes, for example as part of the Xn establishment process or as part of the Xn NG-RAN node configuration update process.

[0019] In some example embodiments, the frequency indication is sent in one of the following ways: update, update confirmation, request, or response.

[0020] In some example embodiments, a network node is configured to determine that the operating frequency of at least one cell is different from the service frequency of the serving primary cell and any serving secondary cell, based on receiving a message from the serving network node indicating the operating frequencies of the serving primary cell and any serving secondary cell, and based on determining whether at least one potential candidate cell used to be added as a primary or secondary cell during a handover to the network node with a secondary cell group uses a frequency different from the operating frequencies of the serving primary cell and the serving secondary cell to provide radio coverage; and based on the determination, generate an indication of the frequency.

[0021] In some example embodiments, while acting as a serving network node to a user equipment, a network node is configured to: in response to receiving an indication from a target network node of at least one operating frequency of at least one potential candidate primary / secondary cell, the at least one operating frequency being different from a first serving frequency and at least one additional serving frequency, the response includes generating an indication for transmission to the user equipment, the indication instructing the user equipment to perform a measurement, the measurement including at least one measurement at at least one operating frequency of at least one potential candidate primary / secondary cell, which is different from the first serving frequency and at least one additional serving frequency.

[0022] In some example embodiments, a network node is configured to: receive a handover request from a serving network node, the handover request including a measurement report from a user equipment, the measurement report including at least one measurement at at least one frequency for a potential primary / secondary candidate cell that is different from the operating frequencies of the serving primary and secondary cells; and forward the at least one measurement to a network node that supports providing radio coverage in the potential primary / secondary candidate cells.

[0023] At least one measurement can be forwarded as part of a secondary node add request.

[0024] In some example embodiments, a network node is configured to: receive a measurement report from a user equipment, the measurement report including at least one measurement at at least one operating frequency different from a first service frequency and at least one additional service frequency; generate a handover request for transmission to a target network node, the handover request including an indication of the results of the user equipment measurement at at least one operating frequency different from the first service frequency and at least one additional service frequency.

[0025] According to various (but not necessarily all) exemplary embodiments of the present invention, according to one aspect, a method is provided to be performed at a network node for supporting the provision of radio coverage to a user equipment, the user equipment being configured to support carrier aggregation and dual connectivity, the carrier aggregation including at least a first serving frequency of a serving primary cell and at least one additional serving frequency of at least one serving secondary cell, the method comprising: determining at least one cell, the at least one cell being added as a potential candidate cell for primary / secondary cell addition during a handover of the user equipment from a serving network node to the network node having a group of secondary cells and when the operating frequency of the at least one cell differs from the serving frequencies of the serving primary cell and any serving secondary cell for the user equipment; generating an indication of the operating frequencies of the at least one potential candidate primary / secondary cell for transmission to the serving network node.

[0026] In some example embodiments, the method includes determining which of at least one potential primary / secondary cell is the preferred candidate cell, and generating an indication of frequency only for the preferred primary / secondary cell.

[0027] In some example embodiments, the method includes: in response to a message received from at least one of Operations Management and Maintenance (OAM) messages, or a message generated by a self-organizing network (SON) module or machine learning / artificial intelligence (AI / ML) module associated with the network, determining which of the potential candidate primary / secondary cells is the preferred candidate primary / secondary cell.

[0028] In some example embodiments, messages received from OAM, SON, AI / ML include multiple potential candidate secondary cells that can provide indications of preferred coverage for user equipment.

[0029] In some example embodiments, the method includes transmitting a frequency indication to the serving network node as a switching information element.

[0030] In some example embodiments, the method includes: receiving a handover request from a serving network node, the handover request including a measurement report from a user equipment, the measurement report including at least one measurement at at least one frequency for a potential primary / secondary candidate cell that is different from the operating frequencies of the serving primary and secondary cells; and forwarding the at least one measurement to a network node that supports providing radio coverage in the potential primary / secondary candidate cells.

[0031] In some example embodiments, the method includes: receiving a message from a serving network node indicating the operating frequencies of a serving primary cell and any serving secondary cell, and determining, based on whether at least one potential candidate cell used to be added as a primary or secondary cell during a handover to the network node with a group of secondary cells uses a frequency different from the operating frequencies of the serving primary cell and the serving secondary cell to provide radio coverage, that the operating frequency of at least one cell is different from the service frequencies of the serving primary cell and any serving secondary cell, and determining, based on the indication of generating the operating frequency.

[0032] In some example embodiments, the method includes, while acting as a serving network node for a user equipment, performing the following steps in response to receiving an indication from a target network node of at least one operating frequency of at least one potential candidate primary / secondary cell, the at least one operating frequency being different from a first serving frequency and at least one additional serving frequency, the response including generating an indication for transmission to the user equipment, the indication instructing the user equipment to perform a measurement, the measurement including at least one measurement at at least one operating frequency of at least one potential candidate primary / secondary cell, which is different from the first serving frequency and at least one additional serving frequency.

[0033] In some example embodiments, the method includes: receiving a measurement report from a user equipment, the measurement report including at least one measurement at at least one operating frequency different from a first service frequency and at least one additional service frequency, and in response, generating a handover request for transmission to a target network node, the handover request including an indication of the results of the user equipment measurements at at least one operating frequency different from the first service frequency and at least one additional service frequency.

[0034] According to various (but not necessarily all) exemplary embodiments of the present invention, a computer program is provided that includes computer-readable instructions, which, when executed by a processor on a network node, cause the network node to perform a method according to one aspect or some exemplary embodiments of one aspect.

[0035] According to various (but not necessarily all) exemplary embodiments of the present invention, a network node is provided for supporting the provision of radio coverage to a user equipment configured to support carrier aggregation and dual connectivity, wherein the carrier aggregation includes at least a first serving frequency of a serving primary cell and at least one additional serving frequency of at least one serving secondary cell, the network node comprising: components for determining at least one cell, the at least one cell being a potential candidate cell to be added as a primary / secondary cell during a handover of the user equipment from the serving network node to the network node having a group of secondary cells, wherein the operating frequency of the at least one cell is different from the serving frequencies of the serving primary cell and any serving secondary cell for the user equipment; and components for generating an indication of the operating frequencies of the at least one potential candidate cell for transmission to the serving network node.

[0036] The component can be configured to perform the optional features mentioned above regarding the device.

[0037] According to various (but not necessarily all) exemplary embodiments of the present invention, a non-transitory computer-readable medium is provided having program instructions stored thereon, which, when executed by a processor on a network node, cause the network node to perform at least the following operations: determining at least one cell, the at least one cell being added as a potential candidate cell for primary and secondary cells during a handover of a user equipment from a serving network node to the network node having a secondary cell group and when the operating frequency of the at least one cell is different from the service frequency of the serving primary cell and any serving secondary cell for the user equipment; and generating an indication of the operating frequency of the at least one potential candidate cell for transmission to the serving network node.

[0038] The instructions can be used to execute the optional features mentioned above regarding the method.

[0039] Further specific and preferred aspects are set forth in the appended independent and dependent claims. Features of the dependent claims may be suitably combined with features of the independent claims, and may be combined in ways not expressly stated in the claims.

[0040] When a device feature is described as operable to provide a function, it should be understood that this includes device features that provide the function or are adapted or configured to provide the function. Attached Figure Description

[0041] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 The diagram illustrates that, according to the first embodiment, the measurements can exist in a measurement report generated by the user equipment to support conditional handover (CHO) of a cell with a secondary cell group (SCG); Figure 2 The diagram illustrates that, according to the second embodiment, the measurements can exist in a measurement report generated by the user equipment to support a cell with a CHO having an SCG; Figure 3A The diagram illustrates the mobility of user equipment supporting carrier aggregation and dual connectivity relative to the primary and secondary cells. Figure 3B The illustration shows the provision Figure 3A The user equipment and network nodes of the radio coverage area are shown. Figure 4 A high-level exemplary signaling diagram of CHO with 5G secondary cell group is shown; Figure 5 Detailed Figure 4 The measurement configuration and measurement report shown in step 0; Figure 6 The extraction of measResultServingMOList is shown; Figure 7 It is shown that servingCellMO is a measObjectId pointing to MeasObjectNR, and its ssbFrequency is equal to the frequency of the serving cell; Figure 8 Step 0 is shown: Measurement configuration and reporting, which reports the best neighbor cell for each serving cell; Figure 9 A diagram is provided showing the changes in MeasConfig to configure the UE to measure and report the best neighbor cell on candidate (non-serving) carrier frequencies; Figure 10The diagrams provide illustrations of changes in MeasResults to allow the UE to report measurements of multiple best neighbor cells on carrier frequencies different from the serving cell's carrier frequency, and also provide illustrations of the scenario where measId1, linked to MeasObjectId1, triggers a measurement reporting message. Figure 11 This illustrates a scenario where measId2, which is linked to MeasObjectId2, triggers a measurement report message; Figure 12 It shows how to make it possible to prepare the SN addition for PSCell on candidate non-service frequency F3 and the SN addition for PSCell on candidate non-service frequency F4 when a single measurement report is received; Figure 13 It shows how to report measurements for several best neighboring cells at each service frequency.

[0042] Figure 14 The process of establishing Xn is shown; and Figure 15 The NG_RAN node configuration update process is illustrated. Detailed Implementation

[0043] Before discussing the example embodiments in more detail, an overview will be provided first.

[0044] During handover with a secondary cell group, the measurements routinely transmitted by the user equipment in the information element (IE) for potential primary and secondary cells are limited to the best neighbor cell operating at the same frequency as each serving secondary cell. This restricts the selection of potential primary and secondary cells. Embodiments attempt to increase the selection of primary and secondary cells during handover by providing additional measurements associated with multiple candidate primary and secondary cells (i.e., serving primary and serving secondary cells) at the serving frequency of the serving secondary cell (used for carrier aggregation) or at frequencies different from the current serving frequency. These measurements are sent in a single measurement report, thus providing information without adding latency.

[0045] Figure 1 A plurality of serving cells 10, 12A, and 12B are schematically shown, including a serving primary cell 10 operating at a first serving frequency F1, and two serving secondary cells 12a and 12b operating at frequencies F2 and F5, respectively. The radio coverage of these serving secondary cells is at least partially within the radio coverage of the serving primary cell, and user equipment configured for carrier aggregation is able to transmit / receive data via each cell at the corresponding serving frequency.

[0046] Figure 1Cells 20 and 22 and 22B, representing candidate primary and secondary cells for potential handover, are also schematically shown. The user equipment generates a measurement report for transmission to the network node for use in handover decisions, and the measurement report may include measurements for a plurality of candidate primary cells 20, each operating at serving frequency F1, and measurements for one best neighbor cell 22a, 22b for each frequency (i.e., F2 and F5) of the serving secondary cell. These measurements are present in a regular UE measurement report transmitted to the source node for conditional handover with a group of secondary cells. This report provides a limited number of secondary cells that can be considered and prepared in handover situations, and embodiments seek to increase the number of potential target primary and secondary cells, thereby improving the addition of secondary nodes during handover. In this example embodiment, measurements of neighbor cell 22c operating at frequency F3 and neighbor cell 22d operating at frequency F4 are transmitted in the same measurement report along with measurements for potential target cells operating at the serving frequency.

[0047] Figure 2 An alternative example embodiment is shown, in which the measurement report does not provide added cell measurements for cells operating at non-serving frequencies, but rather for added cells 22c and 22d operating at the same serving frequency as the serving secondary cell. Therefore, in this case, as in the previous example embodiment, added cell measurements associated with candidate primary and secondary cells are transmitted in the user equipment measurement report, thereby increasing the selection of cells that can be added as primary and secondary cells during handover. Since these measurements appear in the same single measurement report, there is no additional delay, and the selected cell can be prepared for addition during the handover process.

[0048] Figure 3A This is an example of a two-layer radio coverage network configuration.

[0049] The UE is configured with a CA configuration consisting of PCell (F1), first SCell (F2), and second SCell (F5), where F1, F2, and F5 represent different serving carrier frequencies of the CA configuration. The serving cell refers to PCell (F1), first SCell (F2), or second SCell (F5).

[0050] Figure 3AThe coverage areas of serving primary cell 10 PCell1 (operating at frequency F1 under network node MN1 (primary node 1)) and target primary cell 20 PCell2 (operating at frequency F1 under network node MN2 (primary node 2)) are shown. Smaller, shallower circles indicate the coverage areas of the primary and secondary PSCells operating at different frequencies. In PCell1 coverage, PSCell1 and PSCell2 have coverage areas schematically shown by circles or bubbles, and operate at frequencies F10 and F20, respectively. Similarly, in target primary cell PCell2 coverage, PSCell3 and PSCell4 operate at frequencies F3 and F4, respectively.

[0051] In this example, the UE mobility direction is indicated by an arrow. Figure 3A The first service SCell (F2) and the second service SCell (F5) of the CA configuration are also shown.

[0052] Figure 3A The diagram illustrates a CHO with SCG changes. The UE has dual connectivity and is served by cells PCell1 (F1) and PSCell2 (F20), and moves toward target MN2 and will switch to dual connectivity with cells PCell2 (F2) and PSCell3 (F3). Therefore, in the CHO, both PCell and PSCell change.

[0053] like Figure 3A As shown, PSCell3 lies within the boundary between PCell1 and PCell2. Whenever the UE switches to PCell2, it can also enter the coverage of PSCell3. In R17 / R18 CHO with SCG, if the UE moves from the shown cell boundary, MN2 may need to configure the UE to have an SCG consisting of PSCell3. To determine whether the UE enters the coverage of PSCell3 when moving towards PCell2, MN1 (controlling PCell1) should configure the UE with PSCell3 frequency (F3) measurements, which will be reported by the UE to MN1 (controlling PCell1). The MeasurementReport sent from the UE includes measurements of the target PCell2 on the adjacent frequency F1 and the cells on serving frequencies F1, F2, and F5, as well as the added non-serving frequency F3 of PSCell3. MN1 (controlling PCell1) then forwards the PCell2 and PSCell3 measurements together to MN2. MN2 can directly reserve resources for PSCell 3, while also reserving resources for PCell2, which avoids the need to add PSCell after the PCell switch is completed.

[0054] The target MN2 can determine the PSCells adjacent to the source PCell1 and the associated frequencies (such as F3) for these PSCells as follows. The UE can hand over to PCell2 without any PSCell3 connection, and then MN2 (controlling PCell2) can (shortly after the handover) establish dual connectivity (DC) with the strongest PSCell under PCell2 coverage. MN2's decision to establish DC can be based on UE measurements reported to MN2 by the UE after the handover. This will clearly indicate to MN2 (controlling PCell2) that PSCell3 is close to the boundary of PCell1. In this way, MN2 can learn the associated PSCell frequencies in the cell boundary of MN1, and MN2 can notify MN1 of the associated frequencies. In this example, MN2 will notify MN1 (e.g., via the Frequency for SCG Addition during Handover Information IE and the Xn NG-RAN node configuration update message) that the cell boundary between PCell1 and PCell2 requires the UE to be configured with measurements of frequency F3. Since frequency F4 is independent of cell boundaries and only relates to the coverage area of ​​PCell2, this frequency may not be reported to MN1, thus avoiding any unnecessary measurement configuration for F4 when PCell1 is serving the UE.

[0055] Figure 3B The configuration of network nodes such as master node MN130 and user equipment 50 is schematically shown. Network node MN2 and auxiliary nodes SN1 and SN2 are configured in a similar manner to MN1. Network node 30 includes a memory 34 for storing computer-readable instructions, a processing circuitry 32 for executing instructions, and a transmission and reception circuitry 36 for transmitting and receiving messages and data to and from user equipment and other network nodes.

[0056] User equipment 50 includes a memory 54 for storing computer-readable instructions, a processing circuitry 52 for executing the instructions, and a transmitting and receiving circuitry 56 for transmitting and receiving messages and data. The user equipment also includes a sensing circuitry for performing measurements, such as measurements of signal strength and / or signal quality of reference signals broadcast by different network nodes.

[0057] To place the above content in context, the embodiment considers a conditional handover CHO with a 5G secondary cell group (SCG) in this example, and... Figure 4 The image is shown in the middle. Figure 4 An exemplary signaling diagram of the process is provided at a high level.

[0058] In step 0, the source MN master node configures measurement and reporting configurations for UE 50 according to TS 38.331 V17.4.0. These reporting configurations are, for example, event-triggered types, such as utilizing event A3 (triggered when a neighboring cell becomes one offset better than a particular cell's SpCell) or A5 (SpCell becomes worse than threshold 1, while a neighboring cell becomes better than threshold 2). SpCell can be the primary cell (spCell of the primary cell group) or PSCell (spCell of the secondary cell group).

[0059] Subsequently, the UE performs the measurements configured by the source MN. When the entry conditions defined for event A3 or A5 are met during the time period defined as the trigger time, the UE initiates a measurement reporting procedure to send the measurement results to the source MN.

[0060] Step 0 is a set of processes detailed in the following paragraphs and forms the core of the processes used in the embodiments.

[0061] In this application, step 0 refers to the RRC reconfiguration process initiated by the source MN to configure in-frequency measurements, thereby detecting candidate PCells (primary cell spCells of the primary cell group) for conditional handover. These event-triggered measurement reporting criteria use events A3 and A5.

[0062] In step 1, the source MN initiates the CHO process by launching an Xn (network interface) handover preparation process. This Xn handover preparation process includes MCG (primary cell group) configuration, and if the user equipment is configured to have an SCG (secondary cell group), it also includes SCG configuration. The source MN includes the (source) SN (secondary node), UE XnAP (Xn application protocol) ID, SN ID, UE context in the (source) SN, and CHO information request IE in the handover request message.

[0063] In step 2, if the candidate MN decides to retain the UE context in the SN, the candidate MN sends an SN add request message to the SN, including the SN UEXnAP ID, as a reference to the UE context established by the source MN in the SN. If the candidate MN decides to change the SN allowable change quantity configuration, the candidate MN sends an SN add request message to the candidate SN, including the UE context in the source SN established by the source MN. Otherwise, the candidate MN may send an SN add request message to the candidate SN that does not include the SN UE XnAP ID or the UE context in the source SN established by the source MN. In the SN add request message, the candidate MN also includes CHO-related information, namely the source MN ID and MN UE XnAP ID, to indicate that the secondary node add preparation process is triggered in relation to the CHO and to enable the SN to identify requests related to the same UE.

[0064] In step 3, the (candidate) SN responds to the SN add request confirmation message. The (candidate) SN may include an indication of the complete or modified RRC configuration.

[0065] In step 3a, for the SN termination bearer using MCG resources, the candidate MN provides Xn-U DL TNL (Xn user plane downlink transport network layer) address information in the Xn-U address indication message.

[0066] In step 4, the candidate MN includes an MN RRC reconfiguration message to be sent to the UE to perform conditional handover in the handover request confirmation message, and may also provide a forwarding address to the source MN. If PDU (Protocol Data Unit) session splitting is performed on the target side during the handover process, the handover request confirmation message includes more than one data forwarding address corresponding to each node. If the candidate MN and SN decide to retain the UE context in the SN in steps 2 and 3, the candidate MN instructs the source MN to retain the UE context in the SN.

[0067] In step 4a, the source MN sends an Xn-U address indication message to the (source) SN. This Xn-U address indication message informs the (source) SN of the conditional switch, which can decide to perform (if applicable) early data forwarding for the SN termination bearer and send an early status transmission message to the source MN.

[0068] In step 5, the source MN sends an RRC reconfiguration message to the UE, including a CHO configuration, which is a list of RRC reconfiguration* messages and associated execution conditions, wherein each RRC reconfiguration* message includes an MCG configuration and may include an SCG configuration from the RRC reconfiguration** message received from the candidate SN in step 3.

[0069] In step 6, the UE applies the RRC reconfiguration message received in step 5, stores the CHO configuration, and replies to the MN with an RRC reconfiguration completion message.

[0070] In steps 7 / 8, the UE maintains a connection with the source MN, and if the UE is configured with a PSCell, it maintains a connection with the source PSCell after receiving the CHO configuration and begins evaluating the CHO execution conditions for (multiple) candidate cells. If at least one CHO candidate cell meets the corresponding CHO execution conditions, the UE detaches from the source MN, applies the stored corresponding configuration for the selected candidate cell, synchronizes to the candidate cell, and completes the RRC handover process by sending an RRC reconfiguration complete* message to the target MN. If the stored configuration for the selected candidate cell includes an SCG configuration, the UE includes an embedded SN RRC reconfiguration complete** message for the target SN. After successfully completing the RRC handover process, the UE releases the stored CHO configuration.

[0071] In step 9, if a bearer that requires SCG radio resources is configured, the UE synchronizes to the (target) SN.

[0072] In step 10, if the RRC connection reconfiguration process is successful, the target MN notifies the (target) SN of the reconfiguration completion message via the SN.

[0073] In step 11, the target MN sends a handover success message to the source MN, notifying the UE that it has successfully accessed the target cell.

[0074] In step 12a / b, the source MN sends an SN release request message to the (source) SN, which includes an indication of the reason for MCG mobility. If the source MN receives the indication from the target MN, the source MN indicates to the (source) SN that the UE context in the SN is maintained. The (source) SN confirms the release request.

[0075] In step 12c, the source MN sends an XN-U address indication message to the (source) SN to transmit data forwarding information. If the PDU session is split on the target side, more than one data forwarding address can be provided.

[0076] In step 12d, the source MN sends a handover cancellation message to other signaling connections or other candidate MNs (if any) to cancel the CHO for the UE.

[0077] In step 12e / f, if the target MN is configured with other candidate PCells associated with other candidate SNs besides the target SN, the target MN sends multiple SN release request messages to the corresponding candidate SNs. Other candidate MNs send SN release request messages to other candidate SNs, if configured. Other candidate SNs acknowledge the release requests.

[0078] In step 13a, the (source) SN sends a report message to the source MN using the secondary RAT (Radio Access Technology) data, including the amount of data delivered to and received from the UE via NR / E-UTRA radio.

[0079] In step 13b, the source MN sends a secondary RAT data usage report message to the AMF to provide information about the NR / E-UTRA resources used.

[0080] In step 14, for bearers using RLC AM, the source MN sends an SN status transmission message to the target MN, including, if necessary, the SN status received from the source SN. If necessary, the target MN forwards the SN status to the target SN.

[0081] In step 15, if applicable, data forwarding is performed from the source side (i.e., the source MN or source SN). If the SN is reserved, data forwarding may be performed for the SN-terminated bearer or QoS flow reserved in the SN.

[0082] In steps 16-19, the target MN initiates a path switching process. If the target MN includes multiple DL TEIDs (tunnel endpoint identifiers) for a PDU session in the path switching request message, then if there is a TEID update in the UPF (User Plane Function), the multiple UL TEIDs for the PDU session's UPF should be included in the path switching confirmation message.

[0083] In step 20, the target MN initiates a UE context release procedure to the source MN.

[0084] In step 21, upon receiving a UE context release message from the source MN, the (source) SN releases the C-plane related resources associated with the UE context toward the source MN. Any ongoing data forwarding can continue. If the UE context hold indication is included in the SN release request message in step 12a, the SN will not release the UE context associated with the target MN.

[0085] Below, we describe an example scenario where the UE is served by the MN using procedures other than handover. If the UE has already been connected to the MN via handover, the RRC reconfiguration is provided to the UE via the initial source MN. Later in this application, we describe an alternative scenario where the measurement configuration is provided only via the source MN. In an embodiment, the measurement configuration can be provided to the UE in the target cell for RRC reconfiguration (via HO ​​command or via conditional reconfiguration).

[0086] It should be noted that step 0 refers to the RRC reconfiguration process initiated by the source MN to configure co-frequency measurements to detect candidate PCells for conditional switching. These event-triggered measurements use events A3 and A5.

[0087] Figure 5 Detailed Figure 4 The measurement configuration and measurement report are shown in step 0.

[0088] In step 0, the source MN applies a measurement configuration process, and the UE applies a measurement reporting process, the purpose of which is to transmit the measurement results from the UE to the source MN. Step 0 is a set of processes detailed in the following sections and constitutes the core processes involved in this application.

[0089] In steps 0.1 / 0.2, the source MN sends an RRC reconfiguration message to the UE, including the same-frequency measurement configuration, to detect candidate PCells for conditional handover. According to TS 38.331 V17.4.0, reporting conditions are identified using a measurement identifier labeled MeasId. The measId is linked to the measurement configuration identified by measObjectId and the associated reporting configuration identified by the report configuration identifier reportConfigId. IE MeasObjectId is used to identify the measurement object configuration. IEReportConfigId is used to identify the measurement report configuration.

[0090] Among the other parameters defined in TS 38.331 V17.4.0, the measurement object defines the frequency of the measurement, which here is the frequency of the service PCell, since the conditional switching is on the same frequency.

[0091] The report configuration defines parameters for event A3 (or event A5) to detect candidate PCells, such as offset, threshold, or trigger time. Event A3 (or event A5) for UE detection of candidate PCells for conditional handover is set to a threshold that is typically 2 to 3 dB lower than the conventional (unconditional) handover threshold.

[0092] The above-described event A3 (or event A5) describes an example of a report configuration used to trigger a report from a co-frequency candidate PCell. Within the scope of this invention, any event can be configured, i.e., A1 to A6+X1, X2, and D1, meaning all events are EventTriggerConfig.

[0093] In step 0.3, the UE detects the neighboring cells of PCell as PCell candidates for conditional handover, and hereby they are referred to as PCell1 and PCell2.

[0094] In step 0.4, the UE sends a measurement report message, which includes measurement results associated with each serving cell in the carrier aggregation (CA) configuration: results on the PCell and multiple best neighbor cells at the frequency of the PCell, and results on each SCell and a single best neighbor cell at the frequency of the SCell.

[0095] Figure 6 The extraction of measResultServingMOList (MCG SCell at F5 is not shown) is illustrated for a CA configuration consisting of PCell (F1), first SCell (F2), and second SCell (F5).

[0096] The UE is configured with a CA configuration consisting of PCell (F1), first SCell (F2), and second SCell (F5), where F1, F2, and F5 represent different carrier frequencies of the CA configuration. The serving cell refers to PCell (F1), first SCell (F2), or second SCell (F5).

[0097] In the context of R17 / R18 Conditional Handover (CHO) with a Secondary Cell Group (SCG), and when the UE sends a measurement report for event A3 (or event A5) that includes a candidate PCell for the same frequency (F1) of the CHO, the UE can also report the best neighbor cell (denoted as BestNeighCell) for each serving cell. If the PCell is on F1, measurements on F2 and F5 may require the configuration of measurement gaps.

[0098] When the entry condition is met on F1 for event A3 (or event A5) during the trigger time, the UE sends a measurement report to the source MN, which includes the measurement results of the best neighbor cell for each serving cell (referred to as measResultBestNeighCell according to TS 38.331 V17.4.0).

[0099] According to TS 38.331 V17.4.0, measResultServingMOList includes several measResultBestNeighCells. The IE measResultServingMOList indicates the measurement results of a measurement cell, which has a reference signal indicated in the serving cell measurement object, including the SpCell, configured SCell(s), and best neighbor cell measurement results within the measurement cell for each serving cell measurement object.

[0100] The MeasurementReport, including measResultBestNeighCell, is reported by the UE to indicate measResultBestNeighCell (F1) for PCell (F1), measResultBestNeighCell (F2) for SCell (F2), and measResultBestNeighCell (F5) for SCell (F5).

[0101] measResultBestNeighCell indicates the measurement result of the best neighbor cell of the serving cell identified by servCellId.

[0102] measResultBestNeighCell includes the physCellId and measResult of the best neighbor cell of the serving cell, identified by servCellId.

[0103] View now Figure 8 The measurement configuration in step 0.1 describes the measurement configuration and reporting for each serving cell, with one best neighbor cell: In step 0.1, the source MN can send an RRCReconfiguration message to the UE, which includes a measurement configuration defined as obtaining a MeasurementReport from the UE that includes the best neighbor cell (denoted as BestNeighCell) for each serving cell. According to TS 38.331 V17.4.0, the source MN sets the servingCellMOIE, enabling the UE to report the measResultServingMOList IE.

[0104] For this purpose, reportAddNeighMeas is also included in ReportConfigNR for event A3 (or event A5).

[0105] For this purpose, in step 0.1, the source MN will first include the field `reportAddNeighMeas` in the `ReportConfigNR IE` for event A3 (or event A5) in the measurement configuration. Therefore, the network informs the UE to include the best neighbor cell for each serving frequency in the measurement report for event A3 (or event A5).

[0106] The term "serving frequency" refers to the frequency of the serving cell in the CA configuration.

[0107] According to TS 38.331 V17.4.0, the source MN should send ReportConfigNR->EventTriggerConfig->reportAddNeighMeas ENUMERATED{setup}OPTIONAL, where ReportConfigNR is for event 3 (or event 5).

[0108] For this purpose, servingCellMO is also included in the ServingCellConfig of PCell and each SCell.

[0109] For this purpose, the source MN should set a servingCellMO for each serving cell. The servingCellMO is the measObjectId of the MeasObjectNR associated with the serving cell in the MeasConfig.

[0110] According to TS 38.331 V17.4.0, the field `reportAddNeighMeas` indicates that the UE should include the best neighbor cell for each serving frequency. The source MN should set TS 38331 IE `servingCellMO` (measObjectId) for each serving cell in the `ServingCellConfig` IE. The serving cell refers to PCell (F1), the first SCell (F2), or the second SCell (F5).

[0111] The source MN requires the UE to search for the best neighbor cell at the same frequency as the serving cell. The servingCellMO (as measObjectId) should point to its ssbFrequency (synchronization signal block frequency), which should be equal to the carrier frequency of the serving cell, and the MeasObjectNR should be equal to that of the serving cell.

[0112] Figure 7 The servingCellMO is shown as measObjectId, and the ssbFrequency of the MeasObjectNR it points to is equal to the frequency of the serving cell (not shown in F5).

[0113] According to TS 38.331 V17.4.0, the servingCellMO as measObjectId should refer to a MeasObjectNR, and the ssbFrequency (ARFCN-ValueNR) of that MeasObjectNR should be included in servingCellConfigCommon as absoluteFrequencySSB.

[0114] The ServingCellConfig IE is used to configure (add or modify) a UE with a serving cell, which can be a PCell or SCell of an MCG, or a PSCell or SCell of an SCG. The parameters in this document are primarily UE-specific, but also partially cell-specific (e.g., in the bandwidth section of the add configuration).

[0115] The source MN should not be configured with any ReportConfig associated with the MeasObject pointed to by the servingCellMO in the ServingCellConfig IE.

[0116] For measurements reported by the UE on frequency F1 of PCell (F1) (or F2 of SCell (F2) or F5 of SCell (F5) respectively), the network only needs to configure (at least) one MeasObject with ssbFrequency of F1 (or F2 or F5 respectively).

[0117] The following describes the measurement configuration for measurement reports with measResultServingMOList.

[0118] exist Figure 8 In this context, step 0 refers to the RRC reconfiguration process initiated by the source MN to configure co-frequency measurements, thereby detecting candidate PCells for conditional switching. These event-triggered measurements utilize events A3 and A5.

[0119] In step 0, if the source MN application has a measurement configuration procedure with reportAddNeighMeas in ReportConfigNR IE and servingCellMO in ServingCellConfig IE, then the UE application has a measurement reporting procedure with measResultServingMOList. Step 0, which constitutes the core of the process applied in this invention, can be as follows: Figure 8 The aforementioned improvements will be made.

[0120] Figure 8 Step 0 is shown. Measurement configuration and reporting for each serving cell with the best neighboring cell.

[0121] The following paragraphs describe the preparation for adding one or more SNs for CHO and SCG.

[0122] The UE is configured with a CA (carrier aggregation) configuration consisting of PCell (F1), first SCell (F2), and second SCell (F5), where F1, F2, and F5 represent different carrier frequencies in the CA configuration. The serving cell refers to PCell (F1), first SCell (F2), or second SCell (F5).

[0123] Step 0 refers to the RRC reconfiguration process initiated by the source MN to configure co-frequency measurements, thereby detecting candidate PCells for conditional switching. These event-triggered measurements use events A3 and A5.

[0124] In R17, the target MN for a candidate PCell targeting a CHO initiates a single SN add-on preparation for each candidate PCell, and it can only be paired with a single candidate PSCell. In R18, the target MN for a candidate PSCell targeting a CHO can initiate multiple SN add-on preparations for each candidate PCell, and it can be paired with multiple candidate PSCells.

[0125] In R17 / R18, when step 0 includes measurement configuration and reporting for each serving cell with the best neighbor cell, the UE sends a measurement report to the source MN in step 0.4, and the source MN can initiate: Multiple preparations for co-frequency conditional handover with candidate PCells At F1 (with multiple preparations for co-frequency conditional handover with candidate PCells), that is, the neighboring cells at F1, including the neighboring cells of the best neighboring cell reported for PCell (F1). Multiple preparations for adding inter-frequency SNs with candidate PSCells At F2 (where multiple preparations are made for the inter-frequency SN with candidate PSCells), i.e., at SCell (F2) and for the best neighbor cell reported for the first SCell (F2). At F5 (with multiple preparations for the inter-frequency SN with candidate PSCells), i.e., SCell (F5) and the best neighbor cell reported for the second SCell (F5).

[0126] One issue related to the R17 / R18 process (Issue No. 1) concerns the addition of SNs that have candidate PSCells only at the frequency of the serving cell, as described below.

[0127] Figure 8Step 0 involves an RRC reconfiguration procedure initiated by the source MN to configure in-frequency measurements to detect candidate PCells for conditional handover. These event-triggered measurements use events A3 and A5. In step 0, if the source MN applies a procedure with measurement configuration of reportAddNeighMeas in the ReportConfigNR IE and a procedure with measurement configuration of servingCellMO in the ServingCellConfig IE, then multiple preparations added by the SN can only be performed using candidate PSCells at the serving cell frequency.

[0128] If a UE is configured with a PCell (F1), a first SCell (F2), and a second SCell (F5), the UE will only report measurements in these frequencies. This allows the network to initiate measurement-based SN addition preparations for candidate PSCells at F2 and F5. If no neighboring PSCells are detected in these frequencies, or if PSCells exist in frequencies other than F2 and F5, the UE will not report them along the serving frequency (Issue No. 1).

[0129] Another issue related to the R17 / R18 process (Issue No. 2) involves each serving cell reporting only one best neighbor cell, as described below.

[0130] Historically, networks have attempted to maintain CA configuration when switching UEs from the source MN to the target MN. This is why networks require UEs to report a single best neighbor cell for each serving cell, PCell, and SCell.

[0131] Step 0 refers to the RRC reconfiguration process initiated by the source MN to configure co-frequency measurements, thereby detecting candidate PCells for conditional switching. These event-triggered measurements use events A3 and A5.

[0132] In step 0, if the source MN application has a measurement configuration procedure in ReportConfigNR IE for reportAddNeighMeas and in ServingCellConfig IE for servingCellMO, then multiple preparations for SN addition can only rely on one best neighbor cell reported by each serving cell.

[0133] If a UE is configured with a Pcell (F1), a first SCell (F2), and a second SCell (F5), the preparation for SN addition can only rely on one best neighbor cell on F2 and another best neighbor cell on F5. If multiple cells are available at that frequency that can be selected by the network due to reasons such as load balancing or other considerations such as network slicing support—or due to proactive preparation of multiple candidate cells for the conditional handover process—the UE will not report more than one cell (Problem No. 2).

[0134] In R17 / R18CHO with SCG, before the source MN begins the conditional handover process by initiating Xn handover preparation, the source MN initiates a measurement configuration process with a measId, which is linked to both MeasObjectId and ReportConfigId: MeasObjectId identifies a MeasObject whose ssbFrequency is the carrier frequency of the PCell (= the carrier frequency of the serving cell PCell of the serving MN); The ReportConfigId identifier includes ReportConfigNR for reportAddNeighMeas (used for eventA3 or eventA5).

[0135] ServingCellMO is included in the ServingCellConfig IE (for PCell and each SCell).

[0136] According to the 3GPP technical specifications, the UE initiates a single procedure for measurement reporting, the purpose of which is to transmit the measurement results to the source MN, where the measurement results are only for candidate PSCells at the frequency of the serving cell (i.e., PCell and SCell).

[0137] This functionality causes an issue because the single process of measurement reporting cannot transmit measurement results to the source MN, where the candidate PSCell is located at a candidate frequency different from the serving cell's candidate frequency (Issue No. 1). The problem is that the measurement report message does not include / provides an IE to report candidate PSCells in carrier frequencies different from the serving frequency. The measurement report message is able to report (multiple) serving / candidate PCells, (multiple) serving / candidate SCells, and a mixture of (multiple) candidate PSCells in the serving frequency, but not (multiple) candidate PSCells in non-serving frequencies.

[0138] This feature leads to the aforementioned problem N°1: Using this single measurement reporting procedure, the UE cannot transmit measurement results to the source MN, where the candidate PSCell is located at a candidate frequency other than the serving cell's candidate frequency. Ultimately, the network cannot know whether it should initiate preparation for a PSCell operating at a non-serving carrier frequency.

[0139] Current 3GPP technical specifications do not allow measurement report messages to include the above mixture of (multiple) candidate PSCells in non-serving frequencies.

[0140] Another issue arises in R17 / R18CHO with SCG: before the source MN initiates the conditional handover process by launching Xn handover preparation, if the source MN applies a measurement configuration procedure with reportAddNeighMeas in ReportConfigNR IE and a measurement configuration procedure with servingCellMO in ServingCellConfig IE, then multiple preparations for SN addition can only rely on one best neighbor cell reported by each serving cell (Issue No. 2). In other words, the source MN / serving cell PCell requires the UE to measure and report adding a neighbor cell = PSCell within the SCG to the serving cell PCell.

[0141] Another issue (issue N°3) that occurs during the current Xn setup process (via XN setup request or XN setup response message) is that the target MN shares the frequency of the cell it controls (via TS 38.423 V17.4.0 9.2.2.12 Serving Cell Information E-UTRA) and the frequencies of its neighboring cells (via TS 38.423 V17.4.0 9.2.2.13 Neighbor Information NR), which can be a candidate PSCell.

[0142] Currently, the source MN cannot know which frequencies the target MN is interested in, and configuring the source MN with all frequencies may not be an option, as there may be too many frequencies.

[0143] Before the source MN configures measurements to know the candidate neighbor PSCells of R17 / R18 CHOs with SCG, the source MN cannot know which frequencies are of interest for CHOs with SCG, or on which frequencies the cells controlled by the target MN are deployed. (=The source MN does not know on which carrier frequency the target MN operates its own cells).

[0144] To at least partially address the aforementioned problem, embodiments of aspect 1 (problem solving No. 2) seek to resolve this issue during the CHO and SCG process by providing the UE with the possibility of switching from a serving cell in the first group of frequencies to a target cell operating in the second group of frequencies. The second group includes at least one additional frequency not supported in the first group, wherein the target cell can operate in serving and / or non-serving frequencies.

[0145] By using a single measurement configuration process, the source MN can more effectively configure the UE to report the target cell not only in the serving frequency but also in the non-serving frequency.

[0146] The UE receives the measurement configuration for the serving cell from the source MN (in MeasConfig), which triggers when to report measurements to the source MN. These reports (MeasResults) also include a new IE to report measurement results for non-serving frequencies.

[0147] The UE receives the measurement configuration for the target / candidate cell in the non-serving frequency from the source MN (in the same MeasConfig), which does not include the triggering of when to report the measurement to the source MN (i.e., no ReportConfig).

[0148] The UE performs measurements and reports a single measurement report indicating the results of the configured measurements.

[0149] Upon receiving this single measurement report, the source MN can initiate conditional handover preparation (with SCG) by forwarding the UE measurement to the target MN.

[0150] Then, the target MN can initiate SN preparation for the target PSCell, which operates not only in the service frequency but also in the non-service frequency.

[0151] According to the embodiment of aspect 1, the above-mentioned problem is solved by using an improved MeasConfig provided by the source MN. Figure 8 Step 0.1).

[0152] When sending a measurement report that includes measurement results of the serving cell (PCell and SCell, if any), the UE is configured to include measurement results of the target cell in candidate carrier frequencies that are different from the serving cell frequency.

[0153] According to an embodiment of aspect 1, candidateFrequencyConf-r18 can be added to configure the UE to measure and report the best neighboring cell in the candidate carrier frequency.

[0154] According to some embodiments of aspect 1, an improvement is sought in TS 38.331 V17.4.0 MeasConfig IE by configuring the UE to measure and report the best neighboring cell in the candidate carrier frequency, which is different from the candidate carrier frequency of the serving cell of the SpCell or SCell, which may be MCG or SCG.

[0155] According to some embodiments of aspect 1, a new information element candidateFrequencyConf-r18 is provided in TS 38.331 V17.4.0 MeasConfig IE.

[0156] Compared to existing technologies, these embodiments, and other embodiments (explained below), do not require configuring multiple measurement IDs; that is, at least one measurement ID per candidate frequency, where new frequencies are added, new measurement objects are added, but existing measurement IDs are used. For UE-reported measurements about candidate frequencies, the network only needs to configure (at least) one MeasObject whose ssbFrequency is a candidate frequency. The network should not configure or bind any ReportConfig to a MeasObject whose ssbFrequency is a candidate frequency.

[0157] The above-described embodiments of aspect 1 improve the measurement configuration to address or at least resolve the R17 / R18 problem N°1.

[0158] Further embodiments of aspect 1 also provide improved MeasResults by the UE (step 0.4).

[0159] When sending a measurement report that includes measurements for the serving cell (PCell and Scell, if any), the UE reports measurements for the best neighboring cell operating at a frequency different from that of the serving cell (Pcell or SCell).

[0160] The implementation adds candidateNeighbourFreqList -r18 to allow the UE to report measurements on multiple best neighbor cells at carrier frequencies different from the serving cell's carrier frequency. The serving cell can be a SpCell or SCell of an MCG or SCG.

[0161] The implementation aims to improve TS 38.331 V17.4.0 MeasResults IE to allow the UE to report measurements on the best neighbor cell on a candidate carrier frequency (IE) that is different from the candidate carrier frequency (IE) of the serving cell.

[0162] The example adds a new information element, candidateNeighbourFreqList-r18, to the MeasResults IE in TS 38.331 V17.4.0.

[0163] Compared to existing technologies, this embodiment does not require configuring several measurement IDs, i.e., at least one measurement ID for each candidate non-service frequency.

[0164] A single measurement report on the serving frequency allows the UE to report measurements on (multiple) candidate frequencies other than the serving frequency. When the UE sends a measurement report to the source MN (triggered by event A3 or event A5) to report the measured candidate PCell of the co-frequency CHO at the PCell serving frequency, the UE additionally includes available measurements on candidate cells in non-serving frequencies.

[0165] In a further embodiment according to aspect 2, problem N°2 is solved: The UE may include more than one best neighbor target cell operating on the serving frequency of the SCell; When sending a measurement report that includes measurement results of the frequencies of (multiple) serving cells (PCell and SCell, if any), the UE reports measurement results of multiple neighboring cells operating at the same frequencies as the serving cell (SCell).

[0166] Another embodiment adds measResultBestNeighCellList-r18 to allow the UE to report measurements on several best neighbor cells in the carrier frequency of the serving cell, which can be the SpCell or SCell of the MCG or SCG.

[0167] Some additional embodiments aim to improve the MeasResultServMO in TS 38.331 V17.4.0 of the MeasResults IE to allow the UE to report measurements on several best neighbor cells on the carrier frequency of the serving cell. Some further embodiments add a new information element, measResultBestNeighCellList-r18, to the TS 38.331 V17.4.0 MeasResultServMO IE.

[0168] Compared to existing technologies, further embodiments eliminate the limitation of reporting only one best neighbor cell per serving cell.

[0169] According to another embodiment of aspect 2, the measurement report is improved to resolve or at least address the R17 / R18 problem N°2.

[0170] The following discussion focuses on the alignment between nodes to configure measurements for multiple candidate cells, and provides yet another embodiment aimed at addressing problem N°3 according to aspect 3.

[0171] In option 1 of aspect 3, the target MN can notify the source MN about the following frequencies during the Xn setup process (via the XN SETUP REQUEST or XNSETUP RESPONSE message): Allow the target MN to add SCG at these frequencies during switching; The source MN is configured for radio measurements; UE reports radio measurements.

[0172] In Option 1 of Aspect 3, the target MN is also able to notify the source MN about the following frequencies during the NG-RAN node configuration update process (via NG-RAN node configuration update or NG-RAN node configuration update confirmation message): Allow the target MN to add SCG at these frequencies during switching; The source MN is configured for radio measurements; UE reports radio measurements.

[0173] Currently, during the Xn establishment process or NG-RAN node configuration update process, the target MN shares the frequencies of the cells it controls and, possibly, the frequencies of neighboring cells that are actually PSCells. According to another embodiment of aspect 3, the target gNB communicates the frequencies of neighboring cells to the source gNB; these neighboring cells are of interest for (reference) handovers configured with a CHO or even an SCG. Another embodiment of aspect 3 allows the source MN to select frequencies of interest for the target MN (in the prior art, all frequencies of the target PSCell that can be configured by the target MN are communicated during the Xn establishment process or NG-RAN node configuration update process), i.e., if there are too many frequencies (although in reality it may only be a few frequencies), then configuring all frequencies may not be selected. In fact, all frequencies of the target PSCell are communicated during the Xn establishment process (via... Figure 14 (XN establishment request or XN establishment response) or during the NG-RAN node configuration update process (via Figure 15The NG-RAN node configuration update or NG-RAN node configuration update confirmation is communicated.

[0174] In this report, another embodiment of aspect 3 is described using a process from TS 38.423. This further embodiment can also be described using peer processes in TS 36.423 or any future application protocols between future network controllers.

[0175] To be controlled by the UE in step 0 ( Figure 8 The candidate frequencies measured in the UE must be compatible with the UE's capabilities and the target MN's focus on the PSCell for the CHO target MN with SCG (i.e., candidate frequencies on which the possible candidate PSCells operate).

[0176] In one embodiment, the target MN is notified of the frequency associated with SCG addition during handover via 1) OAM, 2) another SON / AI-ML module, or 3) UE measurements reported to the target MN after a handover between MNs without SCG. In the latter case, if the target MN configures an SCG for the UE shortly after performing a single-connectivity handover (HO without target SCG) (on frequency f3), the target MN notifies the source MN of frequency f3, presumably associated with a handover with SCG addition. F3 refers to the subsequent description of the frequency for SCG Addition during Handover Information IE (TS 38.423) regarding the gNB determining frequencies to set up the frequency information during handover for SCG addition.

[0177] In alternative option 2 of aspect 3, the target gNB is notified of the frequency to be added for the SCG via 1) OAM or 2) another SON / AI-ML module.

[0178] Compared to existing technologies, another embodiment of aspect 3 allows the source MN to know the candidate frequencies considered by the target MN for adding to the SCG.

[0179] Figure 8 Step 0 involves an RRC reconfiguration process initiated by the source MN to configure co-frequency measurements to detect candidate PCells for conditional switching. These event-triggered measurements use events A3 and A5.

[0180] Another embodiment of aspect 3 improves the OAM / SON solution to address R17 / R18 problem N°3.

[0181] According to another embodiment of aspect 4, UE capabilities are addressed and problem No. 4 is resolved. Other embodiments of aspect 4 introduce several R17 / R18 UE capability indicators that indicate support for the proposed embodiments.

[0182] For example, a UE capability indicator is provided to the network node / gNB to support the capabilities of the proposed embodiment, namely, "enhanced R17 / R18 target PSCell measurement configuration and reporting in candidate frequencies different from the serving PCell / SCell frequency." This capability supports another proposed embodiment, namely, "enhanced R17 / R18 measurement reporting to include more than one best neighbor target cell operating in the serving PCell / SCell frequency."

[0183] The embodiments attempt to address the above problems using techniques described in more detail below.

[0184] Add candidateFrequencyConf-r18 to configure the UE to measure and report the best neighboring cells in the candidate carrier frequencies.

[0185] According to an embodiment of aspect 1, TS 38.331 V17.4.0 MeasConfig IE is intended to be improved to configure the UE to measure and report the best neighbor cell on a candidate carrier frequency (IE) that is different from the candidate carrier frequency (IE) of the serving cell, which may be a SpCell or SCell of an MCG or SCG.

[0186] In addition, a new information element, candidateFrequencyConf-r18, has been added in TS 38.331 V17.4.0 MeasConfig IE.

[0187]

[0188] The `candidateFrequencyConf` field indicates a set of candidate frequencies different from the serving cell's frequency. The serving cell can be a SpCell or SCell of an MCG or SCG. The UE must perform and report measurements on the best neighbor cell among the candidate frequencies. The UE must perform these measurements on the candidate frequencies while simultaneously performing measurements on the serving cell, the configuration of which is identified by the `MeasId` in `applicableMeasIdList`. The candidate frequencies are indicated by the `ssbFrequency` (i.e., the frequency of the SSB) associated with the `MeasObjectNR`, the configuration of which is identified by the `MeasObjectId` in `applicableMeasObjectIdList`.

[0189] Figure 9 The candidateFrequencyConf is illustrated schematically to configure the UE to measure and report candidate (non-serving) carrier frequencies, i.e., F3 or F4, according to each embodiment.

[0190] The UE is configured with a CA configuration consisting of PCell (F1), first SCell (F2), and second SCell (F5), where F1, F2, and F5 represent different carrier frequencies of the CA configuration.

[0191] Figure 9 A diagram of the changes in MeasConfig is provided to configure the UE to measure and report candidate (non-serving) carrier frequencies, i.e., the best neighboring cell on F3 or F4.

[0192] Therefore, embodiments according to aspect 1 aim to improve MeasConfig to configure the UE to measure and report the best neighboring cell on candidate carrier frequencies (F3 and F4), which are different from the candidate carrier frequencies of the serving cell, which may be PCell (at F1) or SCell (at F2).

[0193] The `candidateFrequencyConf` field indicates a set of candidate frequencies F3 and F4 that differ from the serving PCell (or correspondingly the serving SCell) frequency F1 (or correspondingly F2). The UE must perform and report measurements on the best neighbor cells on candidate frequencies F3 and F4. The UE can report (e.g., provide its measurement results) one or more cells on frequency F3 and / or one or more cells on frequency F4.

[0194] The UE performs these measurements on candidate frequencies F3 and F4, and the UE performs the measurements whose configuration is identified by MeasId1 (for MeasObjectId1 linked to F1) or MeasId2 (for MeasObjectId2 linked to F2) in applicableMeasIdList.

[0195] Candidate frequency F3 (correspondingly, F4) is indicated by the frequency of ssbFrequency associated with MeasObjectNR, i.e., SSB, whose configuration is identified by MeasObjectId3 (correspondingly, MeasObjectId4) in applicableMeasObjectIdList.

[0196] According to another embodiment of aspect 1, candidateNeighbourFreqList-r18 is added to allow the UE to report measurements on multiple best neighbor cells in carrier frequencies different from the serving cell's carrier frequency, which can be a SpCell or SCell of an MCG or SCG.

[0197] This proposal aims to improve the TS 38.331 V17.4.0 MeasResults IE to allow the UE to report measurements on the best neighbor cell from among (multiple) candidate carrier frequencies that are different from the candidate carrier frequency of the serving cell. The proposal adds a new information element, candidateNeighbourFreqList -r18, to the TS38.331 V17.4.0 MeasResults IE.

[0198]

[0199] The `candidateNeighbourFreqList` field indicates a set of measurements taken at candidate frequencies different from the serving cell, which can be a SpCell or SCell of an MCG or SCG. The candidate frequencies are indicated by the frequencies of the SSB associated with the `MeasObjectNR`, and their configuration is identified by `candidateServingCellMOId`. The `measResultBestNeighCellList` field indicates a set of measurements taken at the best neighboring cell among the candidate frequencies.

[0200] The UE is configured with a CA configuration consisting of PCell (F1), first SCell (F2), and second SCell (F5), where F1, F2, and F5 represent different carrier frequencies of the CA configuration, i.e., different service frequencies of the UE.

[0201] Figure 10 A graphical representation of the changes in MeasResults is provided to allow the UE to report measurements on multiple best neighbor cells at carrier frequencies different from the serving cell's carrier frequency.

[0202] Therefore, some embodiments of aspect 1 aim to improve MeasResults to allow the UE to report measurements on the best neighbor cells on candidate frequencies F3 and F4, which are different from the frequency F1 of the serving PCell (F1).

[0203] The field candidateNeighbourFreqList indicates a set of measurements taken at candidate frequencies F3 and F4 that are different from the frequency F1 (or F2) of the service PCell (or correspondingly the service SCell).

[0204] Candidate frequency F3 is indicated by the frequency F3 of the SSB associated with MeasObjectNR, whose configuration is identified by candidateServingCellMOId(MeasObjectId3). The logic is the same for F4.

[0205] The field `measResultBestNeighCellList` indicates a set of measurements of the best neighboring cells on candidate frequency F3. The logic is the same for F4.

[0206] Figure 11 A graphical representation of the changes in MeasResults is provided to allow the UE to report measurements on multiple best neighbor cells at carrier frequencies different from the serving cell's carrier frequency.

[0207] Therefore, some embodiments of aspect 1 aim to improve MeasResults to allow the UE to report measurements on the best neighbor cells on candidate frequencies F3 and F4, which are different from the frequency F1 of the serving PCell (F1).

[0208] Figure 10 and Figure 11 The differences are as follows: Figure 10 The diagram illustrates a scenario where measId1, which is linked to MeasObjectId1, triggers a measurement report message containing multiple cells on F1 and reported cells on F3 (phys Cell Id130, physCellId131) and F4 (physCell Id140, physCellId141).

[0209] Figure 11 This illustrates a scenario where measId2, which is linked to MeasObjectId2, triggers measurement report messages containing multiple cells on F2 and cells on F3 (physCellId232, physCellId233) and F4 (physCellId242, physCellId243).

[0210] The field candidateNeighbourFreqList indicates a set of measurements taken at candidate frequencies F3 and F4, which are different from the frequency F2 of the service SCell (F2).

[0211] Candidate frequency F3 is indicated by the frequency F3 of the SSB associated with MeasObjectNR, whose configuration is identified by candidateServingCellMOId(MeasObjectId3). The same logic applies to F4.

[0212] The field measResultBestNeighCellList indicates a set of measurements on the best neighbor cells at candidate frequencies F3 and F4.

[0213] The acronym BestNeighCell refers to the best neighbor cell in the service frequency or candidate frequency. Figure 10 The proposal demonstrates how it enables reporting measurement results not only to the service frequency but also to the candidate frequencies. Figure 11 The proposal demonstrates how it enables the preparation of SN additions for PSCell at candidate frequency F3.

[0214] Figure 12 The proposal demonstrates how it enables the preparation of SN additions for PSCells at candidate frequency F3, which is described in italics below.

[0215] In step 1, the source MN initiates the CHO procedure by launching an Xn handover preparation procedure that includes MCG configuration and (if the UE is configured with SCG) SCG configuration. The source MN includes the (source) SN, UE XnAP ID, SN ID, UE context in the (source) SN, and CHO information request IE in the handover request message. The source MN is included in step 0.4 in the Xn handover preparation message. The measurement results received from the UE regarding the non-serving candidate frequency (F3 or F4).

[0216] In step 2, if the candidate MN decides to retain the UE context in the SN, the candidate MN sends an SN Add Request message to the SN, including the SN UEXnAP ID, as a reference to the UE context in the SN established by the source MN. If the candidate MN decides to change the SN to allow variable configuration, the candidate MN sends an SN Add Request message to the candidate SN, which includes the UE context in the source SN established by the source MN. Otherwise, the candidate MN may send an SN Add Request message to the candidate SN that does not include the SN UE XnAP ID or the UE context in the source SN established by the source MN. Within the SN Add Request message, the candidate MN also includes CHO-related information, namely the source MN ID and MN UE XnAP ID, to indicate that the SN Add preparation process is triggered in relation to the CHO and to enable the SN to identify requests related to the same UE. The target MN can be achieved by... Candidate PSCells received from source MN on F3 or F4 are included in the Xn handover request message to send an SN add request message. interest.

[0217] According to an embodiment of aspect 2, the possibility of adding measResultBestNeighCellList-r18 is provided to allow the UE to report measurements on several best neighbor cells in the carrier frequencies of the serving cell other than PCell.

[0218] Therefore, according to this embodiment of aspect 2, the aim is to improve the MeasResultServMO of the MeasResults IE in TS 38.331 V17.4.0 to allow the UE to report measurements on several best neighbor cells in the carrier frequencies of the serving cell other than PCell. Further embodiments may also be described using the peering process in TS 36.331, or any future application protocol between the network controller and the user equipment.

[0219] According to an embodiment of aspect 2, a new information element measResultBestNeighCellList-r18 is added to the MeasResultServMO IE in the MeasResults IE of TS 38.331 V17.4.0.

[0220]

[0221] The field “measResultBestNeighCellList” indicates a list of measurements on the best neighboring cells in the frequency range of the serving cell identified by ServCellIndex.

[0222] The above shows the measResultBestNeighCellList, which indicates the best neighbor cell for PCell (F1) and SCell (F2) – the last part is the change to ASN.1 in TS 38.331 V17.4.0.

[0223] The UE is configured with a CA configuration consisting of PCell (F1), first SCell (F2), and second SCell (F5), where F1, F2, and F5 represent different serving carrier frequencies of the CA configuration.

[0224] According to the embodiment of aspect 2, a measResultBestNeighCellList is added to MeasResultServMO in MeasResults to allow the UE to report measurements on several best neighbor cells on carrier frequency F1 of the serving PCell (F1) and carrier frequency F2 of the serving SCell (F2). The field measResultBestNeighCellList indicates a list of measurements on best neighbor cells in the frequency of the serving cell identified by ServCellIndex.

[0225] The acronym BestNeighCell refers to the best neighbor cell in the service frequency or candidate frequency. Figure 13 The illustration shows another embodiment that enables the UE to report measurements of several best neighbor cells for each serving frequency other than the PCell frequency.

[0226] Figure 14 An embodiment of Xn establishment and successful operation related to option 1 of aspect 3 is shown, wherein the target MN can notify the source MN about the non-service frequencies added for the SCG by the target MN during the Xn establishment process (via an XN setup request or XN setup response message).

[0227] exist Figure 15 Option 1 allows the target MN to also notify the source MN during the NG-RAN node configuration update process (via NG-RAN node configuration update or NG-RAN node configuration update confirmation message) about the non-service frequencies that the target MN is considering adding for the SCG during the handover.

[0228] In alternative option 2 of aspect 3, the source gNB receives the preferred frequency of the candidate target MN from the OAM or SON / AI-ML module.

[0229] The following is about Figure 14 The Xn settings provide the following details: These details specify the changes proposed by Option 1 in the Xn Application Protocol (XnAP), namely, the addition of Frequency Information for SCGAddition during Handover Information IE.

[0230] Alternate NG-RAN node configuration update: Specifies the change proposed by option-1 in the Xn Application Protocol (XnAP), which adds the frequency for SCG during the handover information IE.

[0231] The following paragraphs detail how gNB determines the non-service frequencies during the handover period for SCG added in TS 38.423 using IE settings.

[0232] exist Figure 14 In this process, NG-RAN node 1 initiates the procedure by sending an XN SETUP REQUEST message to candidate NG-RAN node 2. Candidate NG-RAN node 2 replies with an XN SETUP RESPONSE message.

[0233] If NG-RAN Node 1 considers the frequency added for SCG during handover, then NG-RAN Node 1 should... The XN SETUP REQUEST message includes SCG frequency information IE added during the handover to notify NG-RAN node 2.

[0234] If NG-RAN Node 2 considers the frequency added for SCG during handover, then NG-RAN Node 2 should... The XN SETUP RESPONSE message includes SCG adding frequency information IE during the handover to notify NG-RAN node 1.

[0235] The embodiment of Option 1 of Aspect 3 introduces changes (above italics) in the NG-RAN node configuration update message and the NG-RAN node configuration update confirmation message to address R17 / R18 issue N°3.

[0236] Figure 15 The NG-RAN node configuration update was successfully completed.

[0237] NG-RAN node 1 initiates the process by sending an NG-RAN node configuration update message to its peer NG-RAN node 2.

[0238] If NG-RAN Node 1 considers the frequency added for SCG during handover, then NG-RAN Node 1 should... The NG-RAN node configuration update message includes SCG adding frequency information IE during the handover to notify NG-RAN node 2.

[0239] If NG-RAN Node 2 considers adding frequencies for SCG during handover, NG-RAN Node 2 should notify NG-RAN Node 1 by including the frequencies added for SCG in the NG-RAN Node Configuration Update Confirmation Message during the handover information IE.

[0240] Option 1, in this embodiment, introduces changes (above italics) in the NG-RAN node configuration update message and the NG-RAN node configuration update confirmation message to address R17 / R18 issue N°3.

[0241] Some embodiments relate to new 5G radios, and specifically to the Multi-RAT Mobility (MRM) concept for 3GPP Rel-18 and later versions, which enables and improves mobility / cell changeover in RANs with a central cell-distributed cell (CU-DU) architecture, enabling operation of different DUs (inter-DU) from different vendors via CU operations (involving the central cell's control plane CU-CP and / or central cell's user plane CU-UP). Dual connectivity supports CHOs with SCG in limited cases, and the following issues should be considered: Question 1: Adding candidate PSCells to the SN is limited to the frequency of the serving cell; Question 2: Only one best neighbor cell is reported per service cell; Question 3: The source MN cannot know which carrier frequencies the target MN is interested in; Some embodiments address the above problems by one or more of the following: When sending a measurement report that includes measurement results for the frequencies of (multiple) serving cells (PCell and SCell, if any), the UE is configured to include the measurement results of the target cell in candidate carrier frequencies that are different from the serving cell frequencies (Aspect 1). When sending a measurement report that includes measurement results for the frequencies of (multiple) serving cells (PCell and SCell, if any), the UE reports the measurement results of the best neighboring cell operating at a frequency different from the serving cell (PCell or SCell) (Aspect 1). The UE may include more than one best neighboring target cell in the SCell's serving frequency in the measurement report (Aspect 2). The source MN is notified (via Xn, OAM, SON, AI-ML) about the following frequencies (aspect 3): (1) the frequencies at which the target MN is allowed to add SCs during handover; (2) the frequencies at which the source MN configures radio measurements; and (3) the frequencies at which the UE reports radio measurements. The UE provides a UE capability indicator to the network node / gNB, enabling the network node to operate with the UE based on the above information (Aspect 4).

[0242] During dual connectivity operations, a CHO with SCG may occur when moving to the serving cell boundary of the serving MN and serving SN. The proposed enhancements aim to avoid this: after changing the target cell to the target MN and target SN, a complete new RRC reconfiguration is required because the target MN / SN operates on a different frequency than the serving MN / SN.

[0243] In some embodiments, the UE receives a new measurement configuration, which may include: Configuration for measuring the target cell at frequencies F3 and F4, where frequencies F3 and F4 are additional frequencies within the target MN2resp.

[0244] Report configurations of more than one best / strongest target cell in "non-service" frequencies; Regarding whether and how to report configurations of more than one best / strongest neighbor cell at the same frequency as the current serving secondary cell; The service gNB / MN determines / obtains information about "non-service frequencies" operating within the coverage area of ​​adjacent MNs; The serving gNB / MN receives a UE capability indicator from the UE indicating whether the UE supports measurements on "non-serving frequencies"; The serving gNB / MN requests and configures measurements and measurement reports from the UE for candidate target cells operating in both serving and non-serving frequencies. Serving gNB / MN: Provides information about the frequencies operated by cells within the coverage area of ​​the serving MN (MCG and SCG cells), and receives a list of frequencies operated by target MNs in addition to those operated by the serving MN. For these added frequencies, the serving MN can request additional measurements and measurement reports from the UE. The target gNB / MN receives the list / set of frequencies currently operating from the serving MN and compares them with the list / set of frequencies currently operating from the target MN. The non-matching frequencies are the "non-serving frequencies" of candidate target cells within the coverage area of ​​the target MN. The target MN provides those "non-serving frequencies" to the serving MN, which can then request the UE to perform new / added measurements.

[0245] Those skilled in the art will readily recognize that the steps of the various methods described above can be performed by a programmed computer. In this document, some embodiments are also intended to cover program storage devices, such as digital data storage media, which are machine- or computer-readable and encoded with machine-executable or computer-executable instructions, wherein the instructions perform some or all of the steps of the methods described above. Program storage devices can be, for example, digital memories, magnetic storage media such as disks and tapes, hard disk drives, or optically readable digital data storage media. Embodiments are also intended to cover computers programmed to perform the steps of the methods described above. Contrary to limitations on data storage persistence (e.g., RAM versus ROM), the term "non-transient" as used herein refers to a limitation of the medium itself (i.e., tangible, not tactile).

[0246] The term "circuit system" as used in this application may refer to one or more of the following: (a) Hardware circuit implementation only (such as implementation in analog and / or digital circuits only) and (b) A combination of hardware circuitry and software, such as (if applicable): (i) A combination of (multiple) analog and / or digital hardware circuits and software / firmware, and (ii) Any part of the (multiple) hardware processors (including (multiple) digital signal processors), software, and (multiple) memories, which work together to enable a device (such as a mobile phone or server) to perform various functions and (c) (Multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or a portion thereof, which require software (e.g. firmware) to operate, but may not exist when the software is not required to operate.

[0247] The definition of "circuit system" applies to all uses of the term in this application, including any claim. As yet another example, as used in this application, the term "circuit system" also covers implementations of hardware circuitry or processors (or processors) or a portion thereof, including but not limited to hardware circuitry or processors and their accompanying software and / or firmware. The term "circuit system" also covers, for example (and if applicable to a particular claim element), baseband integrated circuits or processor integrated circuits for mobile devices or similar integrated circuits in servers, cellular network devices, or other computing or networking devices.

[0248] Although exemplary embodiments of the invention have been described with reference to various examples in the preceding paragraphs, it should be understood that modifications may be made to the given examples without departing from the scope of the claimed invention.

[0249] The features described above may be used in combinations other than those explicitly described.

[0250] Although functions have been described with reference to certain features, these functions can be performed by other features, whether or not they are described.

[0251] Although features have been described with reference to certain embodiments, these features may also exist in other embodiments, whether or not they are described.

[0252] Although efforts have been made in the foregoing description to draw attention to those features of the invention that are considered particularly important, it should be understood that the applicant claims protection for any patentable features or combinations of features mentioned above and / or shown in the drawings, whether or not they have been specifically emphasized.

Claims

1. A network node for supporting the provision of radio coverage to user equipment, the user equipment being configured to support carrier aggregation and dual connectivity, the carrier aggregation including at least a first serving frequency of a serving primary cell and at least one additional serving frequency of at least one serving secondary cell, the network node comprising: At least one processor; as well as At least one memory, the at least one memory storing instructions that, when executed by the at least one processor, cause the network node to at least: At least one cell is identified as a potential candidate cell for addition as a primary / secondary cell during a handover of a user equipment from a serving network node to the network node with a secondary cell group, and when the operating frequency of the at least one cell is different from the service frequency of the serving primary cell and any serving secondary cell for the user equipment. An indication of the operating frequency for generating the at least one potential candidate cell is transmitted to the serving network node.

2. The network node of claim 1, wherein the network node is configured to determine which of the at least one potential primary / secondary cell is a preferred candidate cell, and to generate the indication of the frequency only for the preferred primary / secondary cell.

3. The network node of claim 2, wherein the network node is configured to determine which of the at least one potential primary / secondary cell is the preferred primary / secondary cell in response to a message received from at least one of the Operation Management and Maintenance (OAM) messages, or a message generated by a Self-Organizing Network (SON) module or a Machine Learning / Artificial Intelligence (AI / ML) module associated with the network.

4. The network node of claim 3, wherein the message received from the OAM, the SON, and the AI / ML includes an indication that the plurality of potential candidate primary and secondary cells may provide preferred coverage for the user equipment.

5. The network node according to any of the preceding claims, wherein the network node is further configured to transmit the indication of the frequency to the serving network node as a handover information element.

6. The network node according to any of the preceding claims, wherein the network node is configured such that: Based on receiving a message from the serving network node indicating the operating frequencies of the serving primary cell and any serving secondary cell, and based on determining whether the at least one potential candidate cell used to be added as a primary / secondary cell during a handover to the network node with a secondary cell group uses a frequency different from the operating frequencies of the serving primary cell and any serving secondary cell to provide radio coverage, the operating frequency of the at least one cell is determined to be different from the serving frequency of the serving primary cell and any serving secondary cell; and Based on the determination, the indication of the frequency is generated.

7. The network node according to any of the preceding claims, wherein the network node is such that: A handover request is received from the serving network node, the handover request including a measurement report from the user equipment, the measurement report including at least one measurement at at least one frequency different from the operating frequencies of the serving primary and secondary cells, for the potential primary and secondary candidates; and The at least one measurement is forwarded to a network node that supports providing radio coverage in the potential candidate primary and secondary cells.

8. The network node according to any of the preceding claims, The network node, while serving as a network node for user equipment, is configured such that: In response to receiving an indication from a target network node of at least one operating frequency of at least one potential candidate primary / secondary cell, said at least one operating frequency being different from the first service frequency and said at least one additional service frequency, the response includes generating an indication for transmission to the user equipment, said indication instructing the user equipment to perform a measurement, said measurement including at least one measurement at said at least one operating frequency of the at least one potential candidate primary / secondary cell, which is different from the first service frequency and said at least one additional service frequency.

9. The network node of claim 8, wherein the network node is configured to: A measurement report is received from the user equipment, the measurement report including at least one measurement at at least one operating frequency that is different from the first service frequency and the at least one other service frequency. A handover request is generated for transmission to the target network node, the handover request including an indication of the results of user equipment measurements at at least one operating frequency that is different from the first service frequency and the at least one other service frequency.

10. A method performed at a network node, the network node being configured to support providing radio coverage to a user equipment, the user equipment being configured to support carrier aggregation and dual connectivity, the carrier aggregation including at least a first serving frequency of a serving primary cell and at least one additional serving frequency of at least one serving secondary cell, the method comprising: At least one cell is identified as a potential candidate cell for addition as a primary / secondary cell during a handover of a user equipment from a serving network node to the network node with a secondary cell group, and when the operating frequency of the at least one cell is different from the service frequency of the serving primary cell and any serving secondary cell for the user equipment. Indications for the operating frequencies of the at least one potential candidate primary and secondary cells are generated and transmitted to the serving network node.

11. The method of claim 10, further comprising determining which of the at least one potential candidate primary / secondary cell is a preferred candidate cell, and generating the indication of the frequency only for the preferred candidate primary / secondary cell.

12. The method of claim 11, comprising: In response to a message received from at least one of the Operation Management and Maintenance (OAM) messages, or a message generated by the Self-Organizing Network (SON) module or Machine Learning / Artificial Intelligence (AI / ML) module associated with the network, determine which of the potential candidate primary / secondary cells is the preferred candidate primary / secondary cell.

13. The method of claim 12, wherein the message received from the OAM, the SON, and the AI / ML includes an indication that the plurality of potential candidate secondary cells may provide preferred coverage for the user equipment.

14. The method of claim 11 or 12, further comprising transmitting the indication of the frequency to the serving network node as a handover information element.

15. The method according to any one of claims 10 to 14, comprising: Based on receiving a message from the serving network node indicating the operating frequencies of the serving primary cell and any serving secondary cell, and based on determining whether the at least one potential candidate cell used to be added as a primary or secondary cell during a handover to the network node with a secondary cell group uses a frequency different from the operating frequencies of the serving primary cell and any serving secondary cell to provide radio coverage, the system determines that the operating frequency of the at least one cell is different from the serving frequency of the serving primary cell and any serving secondary cell, and generates the indication of the operating frequency based on the determination.

16. The method according to any one of claims 10 to 15, the method comprising: A handover request is received from the serving network node, the handover request including a measurement report from the user equipment, the measurement report including at least one measurement at at least one frequency for the potential candidate primary and secondary cells, which is different from the operating frequency of the serving primary and secondary cells; as well as The at least one measurement is forwarded to a network node that supports providing radio coverage in the potential candidate primary and secondary cells.

17. The method according to any one of claims 10 to 16, comprising, while acting as a serving network node for a user equipment, performing the following steps: In response to receiving an indication from a target network node of at least one operating frequency of at least one potential candidate primary / secondary cell, said at least one operating frequency being different from the first service frequency and said at least one additional service frequency, the response includes generating an indication for transmission to the user equipment, said indication instructing the user equipment to perform a measurement, said measurement including at least one measurement at said at least one operating frequency of the at least one potential candidate primary / secondary cell, which is different from the first service frequency and said at least one additional service frequency.

18. The method according to any one of claims 10 to 17, comprising: The user equipment receives a measurement report, which includes at least one measurement at at least one operating frequency different from the first service frequency and the at least one other service frequency, and in response, generates a handover request for transmission to the target network node, the handover request including an indication of the results of the user equipment measurements at the at least one operating frequency different from the first service frequency and the at least one other service frequency.

19. A computer program comprising computer-readable instructions that, when executed by a processor on a network node, cause the network node to perform the method according to any one of claims 10 to 18.

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