Method and system for multi-cell target condition switching

Abstract

A user equipment (UE) includes at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, together with the at least one processor, cause the UE to obtain a conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance margin, each of the at least one performance margin being associated with a cell in the multi-cell target that is adjacent to a first cell; determine whether to initiate handover to the first cell based on the at least one performance margin; and send data to the first cell based on the determination of whether to initiate handover.

Description

Technical Field

[0001] One or more example embodiments relate to a wireless communication system. Background Art

[0002] The fifth generation (5G) wireless communication network is the next generation of mobile communication networks. 5G communication network standards are currently being developed by the Third Generation Partnership Project (3GPP). These standards are called 3GPP New Radio (NR) standards. Summary of the invention

[0003] The scope of protection sought by various exemplary embodiments of the present invention is set out by the independent claims. Exemplary embodiments and features described in this specification that do not belong to the scope of the independent claims, if any, are to be construed as useful examples for understanding the various exemplary embodiments of the present invention.

[0004] Conditional Handover (CHO) has two phases. A configured event triggers the User Equipment (UE) to send a measurement report. Based on the report, the source cell prepares the target for handover, including a handover request and a handover request confirmation. The source cell then sends a CHO command to the UE.

[0005] In a system utilizing dual connectivity (DC), the target configuration may include multiple cells.

[0006] For conventional HO, the UE will access the target cell to complete the handover. However, for CHO, the UE will access the target once additional CHO execution conditions are met. This condition is usually configured by the source cell as part of the CHO command.

[0007] The inventors have found that the interference caused by the multi-cell target to the target neighboring cells is not taken into account. For example, when evaluating mobility events such as A3, the cell individual offset (CIO) is considered (3GPP TS 38.331 Section 5.5.4.4 Version 15). However, the CIO is evaluated for the imbalance / difference in signal strength between the source cell and the target cell, not for the cells within the target, nor for the imbalance / difference in signal strength of the cells adjacent to the target cell.

[0008] Furthermore, CHO does not use the aggregate signal strength / quality of the HO target with multiple cells.

[0009] One or more example embodiments provide a mechanism by which a network node, a UE, and a target may perform a conditional handover to a target of multiple cells using interference related margins with respect to cells neighboring the target.

[0010] One or more example embodiments provide a mechanism by which a network node, a UE, and a target may perform a conditional handover using aggregated measurements belonging to the target. The UE considers measurements of the target and its corresponding cells in HO which may be configured in DC or carrier aggregation (CA) operation.

[0011] Furthermore, one or more example embodiments provide a mechanism by which a network node, a UE, and a target may perform conditional handover using a combination of measurement event conditions specific to cells within the target as a condition for performing CHO.

[0012] At least one example embodiment provides a user equipment (UE) comprising at least one processor and at least one memory comprising computer program code. The at least one memory and the computer program code are configured to, together with the at least one processor, cause the UE to: obtain a conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance margin, each of the at least one performance margin being associated with a cell in the multi-cell target that is adjacent to a first cell; determine whether to initiate handover to the first cell based on the at least one performance margin; and send data to the first cell based on the determination of whether to initiate handover.

[0013] In at least one example embodiment, the at least one performance margin is an allowed signal deviation for the first frequency.

[0014] In at least one example embodiment, the allowed signal offset is an allowed difference between a measured signal strength of the first cell and a measured signal strength of a cell neighboring the first cell.

[0015] In at least one example embodiment, the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: measure at least one signal from the first cell; determine whether a condition for conditional switching is met based on the at least one signal measured from the first cell; and if the condition is determined to be met, select the first cell as a switching target cell.

[0016] In at least one example embodiment, the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: measure at least one signal from the source cell; and determine whether a condition for conditional switching is met based on the at least one measured signal from the source cell and the at least one measured signal from the first cell.

[0017] In at least one example embodiment, the at least one memory and the computer program code are further configured to, with the at least one processor, cause the UE to: measure at least one signal from a cell neighboring the first cell; and determine whether to initiate a handover to the first cell based on at least one performance margin, the at least one measured signal from the first cell, and the at least one measured signal from the cell neighboring the first cell.

[0018] In at least one example embodiment, the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: initiate a handover to the first cell when a difference between at least one measured signal from the first cell and at least one measured signal from a cell adjacent to the first cell is less than a performance margin.

[0019] At least one example embodiment provides a user equipment (UE), the UE comprising: a component for obtaining a conditional handover command, the conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance margin, each of the at least one performance margin being associated with a cell in the multi-cell target that is adjacent to a first cell; a component for determining whether to initiate handover to the first cell based on the at least one performance margin; and a component for sending data to the first cell based on the determination of whether to initiate handover.

[0020] In at least one example embodiment, the at least one performance margin is an allowed signal deviation for the first frequency.

[0021] In at least one example embodiment, the allowed signal offset is an allowed difference between a measured signal strength of the first cell and a measured signal strength of a cell neighboring the first cell.

[0022] In at least one example embodiment, the UE further includes: a component for measuring at least one signal from the first cell; a component for determining whether a condition for conditional switching is satisfied based on the at least one signal measured from the first cell; and a component for selecting the first cell as a switching target cell if the condition is determined to be satisfied.

[0023] In at least one example embodiment, the UE further includes a component for measuring at least one signal from a source cell; and a component for determining whether a condition for conditional switching is satisfied based on the at least one signal measured from the source cell and the at least one signal measured from the first cell.

[0024] In at least one example embodiment, the UE further comprises means for measuring at least one signal from a cell neighboring the first cell and means for determining whether to initiate a handover to the first cell based on at least one performance headroom, the measured at least one signal from the first cell, and the measured at least one signal from the cell neighboring the first cell.

[0025] In at least one example embodiment, the UE further comprises means for initiating handover to the first cell when a difference between the measured at least one signal from the first cell and the measured at least one signal from a cell neighboring the first cell is less than a performance margin.

[0026] At least one example embodiment provides a method, the method comprising: obtaining a conditional handover command, the conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance margin, each of the at least one performance margin being associated with a cell in the multi-cell target that is adjacent to a first cell; determining whether to initiate handover to the first cell based on the at least one performance margin; and sending data to the first cell based on the determination of whether to initiate handover.

[0027] In at least one example embodiment, the at least one performance margin is an allowed signal deviation for the first frequency.

[0028] In at least one example embodiment, the allowed signal offset is an allowed difference between a measured signal strength of the first cell and a measured signal strength of a cell neighboring the first cell.

[0029] In at least one example embodiment, the method includes: measuring at least one signal from the first cell; determining whether a condition for conditional switching is satisfied based on the measured at least one signal from the first cell; and if the condition is determined to be satisfied, selecting the first cell as a switching target cell.

[0030] In at least one example embodiment, the method includes measuring at least one signal from a source cell; and determining whether a condition for conditional handover is met based on the measured at least one signal from the source cell and the measured at least one signal from the first cell.

[0031] In at least one example embodiment, the method includes: measuring at least one signal from a cell neighboring the first cell; determining whether to initiate a handover to the first cell based on at least one performance margin, the measured at least one signal from the first cell, and the measured at least one signal from the cell neighboring the first cell.

[0032] In at least one example embodiment, the method includes initiating handover to the first cell when a difference between the measured at least one signal from the first cell and the measured at least one signal from a cell neighboring the first cell is less than a performance margin.

[0033] At least one example embodiment provides a non-transitory computer-readable storage medium storing computer-readable instructions that, when executed at a user equipment (UE), cause the UE to perform a method, the method comprising: obtaining a conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance margin, each of the at least one performance margin being associated with a cell in the multi-cell target that is adjacent to a first cell; determining whether to initiate handover to the first cell based on the at least one performance margin; and sending data to the first cell based on the determination of whether to initiate handover.

[0034] At least one example embodiment provides a user equipment (UE) comprising at least one processor; and at least one memory comprising computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the UE to: obtain a conditional switching command indicating at least one aggregation condition for switching; measure a first signal from a cell in a first multi-cell target; aggregate at least a portion of the measured first signal; and select a switching target based on at least one aggregation condition and the aggregated portion of the measured first signal.

[0035] In at least one example embodiment, the at least one memory and the computer program code are further configured to, with the at least one processor, cause the UE to: obtain an offset value; determine a difference between the measured aggregated portion of the first signal and the offset value; and select a handover target based on the difference.

[0036] In at least one example embodiment, the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: measure a second signal from a cell in a second multi-cell target; aggregate at least a portion of the measured second signal; and select a switching target based on at least one aggregation condition, the aggregated portion of the measured first signal, and the aggregated portion of the measured second signal.

[0037] In at least one example embodiment, the at least one memory and the computer program code are further configured to, with the at least one processor, cause the UE to: select a portion of the measured first signal based on the measured strength of the first signal, the number of the measured portions of the first signal being less than a total number of cells in the first multi-cell target.

[0038] In at least one example embodiment, the number of portions of the first signal measured is greater than one.

[0039] At least one example embodiment provides a user equipment (UE) comprising a component for obtaining a conditional handover command indicating at least one aggregation condition for handover; a component for measuring a first signal from a cell in a first multi-cell target; a component for aggregating at least a portion of the measured first signal; and a component for selecting a handover target based on at least one aggregation condition and the aggregated portion of the measured first signal.

[0040] In at least one example embodiment, the UE further includes means for obtaining an offset value; means for determining a difference between the aggregated portion of the measured first signal and the offset value; and means for selecting a handover target based on the difference.

[0041] In at least one example embodiment, the UE further includes means for measuring a second signal from a cell in a second multi-cell target; and means for aggregating at least a portion of the measured second signal, and means for selecting a switching target based on at least one aggregation condition, the aggregated portion of the measured first signal, and the aggregated portion of the measured second signal.

[0042] In at least one example embodiment, the UE further comprises means for selecting the measured portions of the first signal based on the measured strengths of the first signal, the number of the measured portions of the first signal being less than a total number of cells in the first multi-cell target.

[0043] In at least one example embodiment, the number of portions of the first signal measured is greater than one.

[0044] At least one example embodiment provides a method comprising: obtaining a conditional switching command indicating at least one aggregation condition for switching; measuring a first signal from a cell in a first multi-cell target; aggregating at least a portion of the measured first signal; and selecting a switching target based on at least one aggregation condition and the aggregated portion of the measured first signal.

[0045] In at least one example embodiment, the method further includes: obtaining an offset value; and determining a difference between the aggregated portion of the measured first signal and the offset value, wherein selecting the switching target is based on the difference.

[0046] In at least one example embodiment, the method further comprises: measuring a second signal from a cell in a second multi-cell target; and aggregating at least a portion of the measured second signal, wherein selecting the switching target is based on at least one aggregation condition, the aggregated portion of the measured first signal, and the aggregated portion of the measured second signal.

[0047] In at least one example embodiment, selecting selects the portions of the measured first signal based on strengths of the measured first signals, the number of portions of the measured first signal being less than a total number of cells in the first multi-cell target.

[0048] In at least one example embodiment, the number of portions of the first signal measured is greater than one.

[0049] At least one example embodiment provides a non-transitory computer-readable storage medium storing computer-readable instructions that, when executed at a user equipment (UE), cause the UE to perform a method comprising: obtaining a conditional handover command indicating at least one aggregation condition for handover; measuring a first signal from a cell in a first multi-cell target; aggregating the measured first signal; and selecting a handover target based on at least one aggregation condition and the aggregated measured first signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Example embodiments will be more fully understood from the detailed description given herein below and the accompanying drawings, wherein like elements are represented by like reference numerals, which are given by way of illustration only and thus do not limit the present disclosure.

[0051] Figure 1 An example of conditional switching is shown.

[0052] FIG. 2A to FIG. 2C An example system with dual connectivity is shown.

[0053] Figure 3 A system with two potential targets for handover is shown according to an example embodiment.

[0054] Figure 4A A system with two potential targets for handover is shown according to an example embodiment.

[0055] Figure 4B is a flow chart illustrating a method according to an example embodiment.

[0056] Figure 5 is a flow chart illustrating a method of evaluating a conditional handover (CHO) condition according to an example embodiment.

[0057] Figure 6 A system having at least one target for handover is shown.

[0058] Figure 7 is a flow chart illustrating a method according to an example embodiment.

[0059] Figure 8 is a flow chart illustrating a method according to an example embodiment.

[0060] Fig. 9 A system with two potential targets for switching is shown.

[0061] Fig.10 A system with two potential targets for switching is shown.

[0062] Fig.11 is a block diagram illustrating an example embodiment of a network node.

[0063] Fig.12 A simplified diagram of a portion of a 3GPP NR access deployment is shown for explaining an example embodiment.

[0064] Fig.13 is a block diagram illustrating an example embodiment of a user equipment (UE). DETAILED DESCRIPTION

[0065] Various example embodiments will now be described more fully with reference to the accompanying drawings, in which some example embodiments are shown.

[0066] Detailed illustrative embodiments are disclosed herein. However, the specific structural and functional details disclosed herein are merely representative for the purpose of describing the exemplary embodiments. However, the exemplary embodiments may be embodied in a variety of alternative forms and should not be construed as being limited to the embodiments set forth herein.

[0067] It should be understood that there is no intention to limit the exemplary embodiments to the specific forms disclosed. On the contrary, the exemplary embodiments will cover all modifications, equivalents and alternatives that fall within the scope of the present disclosure. Throughout the description of the drawings, the same numbers refer to the same elements.

[0068] Although one or more example embodiments may be described from a network node (e.g., a radio access network (RAN) element, a base station, an eNB, a gNB, a central unit (CU), an ng-eNB, a WLAN access point or controller, etc.), a user equipment (UE), etc., it should be understood that one or more example embodiments discussed herein may be performed by one or more processors (or processing circuit systems) at an applicable device. For example, according to one or more example embodiments, at least one memory may include or store computer program code, and at least one memory and computer program code may be configured to cause the network node to perform the operations discussed herein together with at least one processor. As discussed herein, UE and user may be used interchangeably. In addition, when a UE or user is within a cell and a node is providing wireless resources for transmissions to / from the UE or user, the UE or user may be referred to as being served by a node or cell. In a WLAN network, a UE or user may be a station (STA).

[0069] In addition, some example embodiments also apply to cells established by UEs, such as UEs with the ability to act as gNBs. Some example embodiments also apply to relay nodes, such as integrated access backhaul (IAB) nodes. It may be applicable to New Radio Unlicensed (NR-U) nodes and UEs. Some example embodiments may also apply to device-to-device (D2D) communications. Some example embodiments apply to MulteFire systems. In general, some example embodiments apply to situations where CHO is used for multi-cell targets.

[0070] It should be understood that various example embodiments may be used in combination.

[0071] Throughout the description, the cell of a particular network node (e.g., base station, eNB, gNB, ng-eNB) is described as the "serving cell" or "source cell" for a particular UE. Transmissions to and from the UE are provided through the network node, and the coverage area of ​​the network node may be referred to as the "serving cell" or "source cell" for the UE. Depending on the context, we may use the term "cell" to refer to the transmission coverage area of ​​a particular network node or to the network node itself. Typically, the area in which transmissions from neighboring network nodes may be received will have some overlap with the area in which transmissions from the serving network node may be received. The UE may also be able to receive transmissions from one or more network nodes in a neighbor set. Conversely, it may be possible to receive signals for an uplink transmission of a given UE not only at its serving cell but also at one or more neighboring cells.

[0072] Figure 1 An example of conditional switching is shown.

[0073] At S150, the source cell sends a measurement control to the UE. The measurement control configures a measurement procedure for the UE. At S155, the UE responds to the measurement control by generating and sending a measurement report to the source cell. S157, the source cell decides whether to use CHO to switch the UE. In some example embodiments, the source cell decides whether to use CHO based on the measurement report and radio resource management (RRM) information received at S155. In addition or alternatively, the source cell may decide whether to use CHO based on whether the UE is connected to the source cell. If the source cell decides to use CHO to switch the UE, at S160, the source cell generates and sends a CHO request to one or more target cells based on the measurement report to which the (multiple) CHO target cells belong. After receiving the CHO request, the (multiple) target cells perform admission control.

[0074] At S170, the target cell confirms the handover request and prepares to receive communications from the UE. Upon receiving the handover request confirmation from the target cell, the source cell sends a CHO command to the UE at S180. The CHO command is used to allow the UE to react more quickly to changing conditions and select a new source cell. However, the UE evaluates the conditions for selecting a new source cell, which in a normal HO would have been performed by the existing source cell.

[0075] In the CHO command, an RRCReconfiguration as set out in Release 15 of 3GPP TS 38.331 is prepared by the source cell and provided to the UE. The RRCreconfiguration may contain configurations for multiple cells, for carrier aggregation (CA), or for dual connectivity (DC). The configuration of multiple cells is included in the RRCReconfiguration, for example as a set of parameters in the information element (IE) CellGroupConfiguration. In CA, the HO first occurs in the target primary cell (PCell), and the secondary cell (SCell) is deactivated after the HO. The target PCell activates the SCell.

[0076] In DC, CHO occurs in the target PCell in the sense that a Radio Resource Control (RRC) connection is established between the PCell and the UE. The PCell then performs a PSCell Add procedure that initiates the establishment of a connection between the PSCell and the UE. The PSCell and the UE will also have an RRC connection. The RRC connection between the PSCell and the UE can be routed via the PCell or directly via a Signaling Radio Bearer (SRB) between the UE and the PSCell.

[0077] In some example embodiments, a DC HO command received by the UE may cause the UE to establish connections to the PCell and PSCell in parallel, for example, by performing random access procedures for both in parallel. Thus, a multi-cell target configuration may be provided in a CHO command because the source cell has already evaluated the suitability of the target cell based on the UE's measurements and other information available to the source cell. In some example embodiments, the source cell has already evaluated the suitability of the target cell before issuing the CHO command to the UE.

[0078] At S185, the UE maintains connection with the source cell after receiving the CHO command and starts evaluating (multiple) CHO target cells. More specifically, the UE monitors communications for conditions to be met. Once the UE determines that the CHO target cell meets the conditions, at S190, the UE initiates a handover to the target cell by performing a random access procedure with the target cell. When the handover is completed, the UE confirms the handover by generating and sending a handover completion confirmation to the target cell at S195 (e.g., an RRCConnectionReconfigurationComplete message as described in Release 15 of 3GPP TS38.331).

[0079] Fig.12 A simplified diagram showing a portion of a 3rd Generation Partnership Project (3GPP) New Radio (NR) access deployment.

[0080] refer to Fig.12 , a 3GPP NR radio access deployment includes a gNB (or node) 100 having transmission and reception points (TRPs) 102A and 102B and a gNB (or node) 200 having TRPs 202A and 202B. Each TRP 102A, 102B, 202A, 202B may be, for example, a remote radio head (RRH) or a remote radio unit (RRU), for example including at least a radio frequency (RF) antenna (or multiple antennas) or an antenna panel and a radio transceiver for transmitting and receiving data within a geographic area. In this regard, the TRPs 102A, 102B, 202A, 202B provide cellular resources to user equipment (UE) within a geographic coverage area known as a cell. In Fig.12 In the example shown, the TRPs 102A, 102B, 202A, 202B are configured to communicate with one or more UEs (e.g., UE or user 106) via one or more transmit (TX) / receive (RX) beam pairs. The gNBs 100 and 200 communicate with the core network, which may be referred to as the Next Generation Core (NGC) in 3GPP NR.

[0081] TRPs 102A, 102B, 202A, 202B can have independent schedulers, or gNBs 100 and 200 can perform joint scheduling between their corresponding TRPs.

[0082] although Fig.12 Only a single UE 106 is shown, but the gNBs 100 and 200 and their corresponding TRPs 102A, 102B, 202A, 202B can provide communication services to a relatively large number of UEs within the cell.

[0083] FIG. 2A to FIG. 2C A system with dual connections is shown.

[0084] Figure 2A The Evolved Universal Terrestrial Radio Access New Radio Dual Connectivity (EN-DC) system is shown. Figure 2A As shown, UE 205 can communicate with evolved Node B (eNB) 210 and next generation Node B (gNB) 215. Figure 2A In the EN-DC system of FIG. 2, the eNB 210 serves as a master node and the gNB 215 serves as a secondary node. Therefore, communication with the UE 205 and the eNB 210 occurs across the user plane 218 and the control plane 219 via the Uu interface 231. Communication between the UE 205 and the gNB 215 occurs across the user plane 220 via the Uu interface 232. Communication between the UE 205 and the gNB 215 (e.g., PSCell) may also occur via SRB (SRB3) to provide a control plane connection 221 via the Uu interface 232. The eNB 210 and the gNB 215 communicate via an X2 control (X2-C) interface 225 and an X2 user (X2-U) interface 230. Both the eNB 210 and the gNB 215 communicate with an evolved packet core (EPC) 240. The eNB 210 communicates with the EPC 240 via an S1 control (S1-C) interface 242 and an S2 user (S1-U) interface 242. The gNB 215 communicates with the EPC 240 via an S1-U 246.

[0085] Figure 2B A New Radio Dual Connectivity (NR DC) system is shown. Figure 2B As shown, UE 205 can communicate with gNB 250 and gNB 255. Figure 2BIn the NR DC system, gNB 250 acts as a primary node and gNB 255 acts as a secondary node. gNB 250 provides a primary cell (PCell) and gNB 255 provides a primary secondary cell (PSCell). Therefore, communication with UE 205 and gNB 250 occurs across the user plane 258 and the control plane 260 via the Uu interface 266. Communication between UE 205 and gNB 255 occurs across the user plane 261 via the Uu interface 267. Communication between UE 205 and gNB 255 may also occur via SRB (SRB3) to provide a control plane connection 262 via the Uu interface 267. gNB 250 and gNB 255 communicate via an Xn control (Xn-C) interface 265 and an Xn user (Xn-U) interface 270. Both gNB 250 and gNB 255 communicate with the Next Generation Core (NGC) 270. gNB 250 communicates with NGC 270 via a next generation control (NG-C) interface 272 and a next generation user (NG-U) interface 274. gNB 255 communicates with NGC 270 via NG-U 276. gNB 250 may also be an eNB capable of having Xn and NG interfaces.

[0086] In CA, a single gNB (e.g., gNB 250) has an NG connection to the NGC and a Uu interface to the UE 205. A single gNB establishes multiple cells on different frequencies. One of the established cells is the primary cell that carries the RRC connection. The cells can overlap in coverage or can be separated by remote radio heads.

[0087] Figure 2C An NR or LTE DC system with multiple DC configurations is shown.

[0088] The CHO command will contain the configuration of possible HO targets. Thus, the target is a cell or a group of cells in a CA or DC configuration. In CHO, not only a single target but multiple targets may be provided to the UE in a CHO command or in separate CHO commands. Thus, the UE is able to evaluate the HO conditions of different targets entering the field of view based on their trajectories.

[0089] In practice, a gNB or eNB may know its neighbors, for example, to provide measurement configurations with reference to the neighbors of a UE, and also issue HO commands for the neighbors of a UE, and communicate with its neighbors via an Xn or X2 interface. A gNB may also have neighbors but no Xn interface with these neighbors. A gNB or eNB may also know the neighbors of its neighbors. This may be achieved through corresponding signaling on the Xn interface, where neighbors may exchange lists of records, each record of a neighbor providing information including a physical cell identifier (PCI), a cell global identity (CGI), a tracking area code (TAC), etc.

[0090] Neighbor information may be exchanged as an information element. In some example embodiments, as described in 3GPP TS 38.423 Release 15, neighbor information may be exchanged as part of the XnSetup procedure in the NeighbourInformation IE in the ServedCells IE. The corresponding information element may be enhanced to carry additional information about the tolerable imbalance parameters mentioned in some example embodiments. In some example embodiments, the information element may be exchanged using a new procedure that does not rely only on XnSetup.

[0091] like Figure 2C As shown, dual connectivity group 275 and dual connectivity group 285 communicate with each other via Xn interface 294. Xn interface 294 may include user plane and control plane communications. Dual connectivity group 275 includes gNB 280 providing PCell and gNB 282 providing PSCell. gNB 280 and gNB 282 communicate with each other via Xn interface 294. Figure 2B The dual connectivity group 285 includes a gNB 292 providing a PCell and a gNB 290 providing a PSCell. The gNB 292 and gNB 290 communicate with each other and with the NGC 270 in a similar manner as described in FIG. Figure 2B The galaxies communicate with each other and with NGC 270 in a manner similar to that described in .

[0092] This article will focus on Fig.12 The 3GPP NR access deployment shown in FIG. 1 describes more specific details of the example embodiment. FIG. 2A to FIG. 2C and Fig.12 Various access deployments are shown in FIG. 1 , but the following discussion may more generally refer to eNBs and gNBs as cells or network nodes. In addition, it should be understood that the example embodiments should not be limited to Figure 2A To Figure C and Fig.12 Example access deployment shown.

[0093] Figure 3 A system with two potential targets for switching is shown. Figure 3 As shown, UE 302 is in communication with source cell 305. Based on the location of UE 302, UE 302 has a first target configuration 310 for handover and a second target configuration 315 for handover.

[0094] exist Figure 3In the example shown, the first target configuration 310 includes a cell 317 configured to provide dual connectivity and a cell 320. The cell 317 may operate as a PCell and may provide a coverage primary cell 325. The cell 320 may operate as a PSCell and may provide a coverage primary secondary cell 330. Although the coverage secondary cell 330 is shown as being completely within the coverage primary cell 325, example embodiments are not limited thereto.

[0095] The RRC reconfiguration includes secondaryCellGroup IE and masterCellGroup IE, each of which includes SpCell IE that configures the primary cell (PCell or PSCell). Therefore, information about potential PCell and PScell ​​can be provided to the UE.

[0096] It should be understood that the primary coverage cell and the secondary coverage cell may partially overlap or may not overlap.

[0097] The second target configuration 315 includes a cell 335 configured to provide dual connectivity and a cell 340. The cell 335 may operate as a PCell and provide coverage for a primary cell 345. The cell 340 may operate as a PSCell and provide coverage for a primary secondary cell 350.

[0098] When switching to a target configuration with a multi-cell configuration, the cells within the target configuration may show weaker strength compared to other neighboring cells using the same frequency. This may result in higher interference from intra-frequency neighboring cells.

[0099] For example, if a handover occurs from the source cell 305 to the first target configuration 310 including the cell 317 because the first target configuration 310 has a higher guaranteed bit rate (GBR) than the second target configuration 315, uplink (UL) interference will occur if the UE 302 is closer to the target cell 335 than the target cell 317 and the target cell 335 and the target cell 317 use the same frequency / carrier / subband. In addition, the communication from the target cell 335 will cause downlink (DL) interference to the communication sent by the target cell 317 and received by the UE 302.

[0100] When evaluating mobility events such as A3, cell individual offset (CIO) is also considered, such as described in 3GPP TS 38.331 section 5.5.4.4 Release 15. However, CIO is evaluated for the imbalance / difference in signal strength between the source cell and the target cell, not for cells within the target, nor for the imbalance / difference in signal strength of cells adjacent to the target.

[0101] Thus, at least some example embodiments use interference-related margins with respect to neighboring cells on a frequency / carrier / subband during CHO. The margins may be specific to neighbors of a cell in the target using the same frequency. Furthermore, the margins may be set by the target cell of the handover based on tolerable interference.

[0102] Currently, the events apply to cells belonging to a single target cell of a handover, not the aggregate quality, nor to neighboring cells of the target cell.

[0103] Interference Correlation Margin

[0104] The CHO condition can evaluate the received signal strength of several possible target cells provided in the measurement configuration based on the received signal strength relative to the source cell. With existing mechanisms, the strongest cell on a given frequency can be selected by basing the HO decision on measurements of a single cell such as reference signal received power (RSRP) or reference signal received quality (RSRQ). This avoids undue interference to other cells.

[0105] With the introduction of multiple cell targets, there may be some cells in the cells of the final selected target that are weaker than those of the neighboring targets. For example, if the DC target is selected based only on the RSRP of the PCell in the selected target, there may be a large strength imbalance between the PSCell of the selected target (on a different frequency) and the intra-frequency neighbors of the PSCell cell.

[0106] Furthermore, in CHO, measurements taken earlier and reported by the UE to the gNB may be outdated when the conditions are met.

[0107] In some example embodiments, the conditions for performing CHO on a HO target comprising multiple cells include an interference-related margin to other neighboring cells on a specific frequency / carrier / subband. The margin may be specific to the neighbors of the cell configured using the same frequency. The margin may be transmitted to the UE as part of the CHO command. In some example embodiments, the margin may be set by the neighbors of the target cell. In other example embodiments, the margin may be set by the target cell when the target cell knows the allowed interference-related margin of its neighbors. The margin may be set to a default value by the source cell.

[0108] Figure 4A A system with two potential targets for switching is shown. Figure 4A As shown, UE 402 is in communication with source cell 405. Based on the location of UE 402, UE 402 has a first target configuration 410 for handover and a second target configuration 415 for handover.

[0109] The first target configuration 410 includes a cell 417 configured to provide dual connectivity and a cell 420. The cell 420 may operate as a PCell and provide coverage for a primary cell 430. The cell 417 may operate as a PSCell and provide coverage for a primary secondary cell 425.

[0110] Second target configuration 415 includes cell 435. Cell 435 provides coverage for cell 445. Cell 435 provides a cell adjacent to target configuration 410. Although second target configuration 415 does not show multiple cells, example embodiments are not limited thereto. In addition, although first target configuration 410 is shown as a DC configuration, it should be understood that example embodiments are not limited thereto and may be implemented in a target having a CA configuration or in a cell on a different frequency.

[0111] exist Figure 4A In a system of , both cell 417 and cell 435 use the same frequency f1 (eg, operate on the same carrier as the download frequency, the upload frequency, or both). Cell 420 uses frequency f2.

[0112] In this system, CHO may be performed by the source cell 405, the UE 402, and any of the cells 417, 420, and 435 using interference-related margins, such as Figure 4B shown.

[0113] Figure 4B is a flow chart illustrating a method according to an example embodiment.

[0114] At S450, source cell 405 generates a CHO request and sends the CHO request to cell 420. Source cell 405 generates the CHO request based on the connection between the UE and the source cell. Source cell 405 may send the CHO request to all its neighbors (i.e., also cell 435). In some example embodiments, if source cell 405 previously received a measurement report ( Figure 4B 4 ), the source cell 405 may choose to send a CHO request only to the target whose strength reported by the UE 402 is above the threshold. Based on the CHO request sent at S450, the target cell 420 performs admission control, reserves resources, and takes other steps used in HO for the UE 402. In at least one example embodiment, the target cell 420 also prepares a cell 417 (not shown in FIG. 4 ) for CHO of the UE 402 based on the CHO request sent at S450. In another embodiment, the source cell 405 sends a separate CHO request to the cell 417 (not shown in FIG. 4 ).

[0115] At S455, cell 420 responds to the request by generating and sending a CHO confirmation to source cell 405. In the CHO confirmation, cell 420 includes the allowed performance margin. If cell 435 is known to cell 420, cell 420 may include the allowed performance margin of cell 435 in the CHO confirmation. In addition, cell 420 may include information about the allowed performance margin of cells in the same target. For example, cell 420 may include information about the allowed performance margin of cell 417. In another example embodiment, if source cell 405 has sent separate CHO requests to target cells 420 and 417, and cell 417 is aware of the performance margin of its neighboring cell 435, cell 417 may include the allowed performance margin associated with cell 435 in the CHO confirmation.

[0116] The allowed performance margin may be a threshold interference level or a maximum UL transmit power associated with a neighboring cell, but is not limited thereto. The threshold interference level and the maximum UL transmit power are values ​​determined by the neighboring cell and are values ​​that the neighboring cell can tolerate from a UE served by a specific cell other than the neighboring cell.

[0117] In some example embodiments, the allowed performance margin is frequency specific and may be the UE measured strength (e.g., RSRP) of a target cell (e.g., cell 417) relative to a neighbor cell strength (e.g., RSRP) in a neighbor target (e.g., cell 435) on the same frequency. In such example embodiments, the allowed performance margin is a signal offset expressed in dB.

[0118] As an alternative to providing the allowed performance headroom in the CHO confirmation at S455, the source cell 405 may generate a query for the allowed performance headroom separate from the CHO request and send the query to the cell 420. The cell 420 may respond to the query by sending the allowed performance headroom of the cell 435 to the source cell 405. In some example embodiments, the query and the signaling of the allowed performance are relayed via the Xn interface using, for example, the Xn Application Protocol (XnAP) protocol. The source cell 405 may also query the cell 417 in a similar manner. If the queried cell has obtained the NeighbourInformation IE including the allowed performance headroom of its neighboring cell 435, the queried cell may respond to the query.

[0119] Each cell may determine the allowed performance margin based on an adaptive and learning algorithm that takes into account interference in the cell, load in the cell, and UE or system performance. For example, a cell may change its associated allowed performance margin based on the number of UEs being served by the cell. When serving a relatively small number of UEs (and / or having a relatively small load), the cell may indicate a relatively large allowed performance margin compared to indicating a relatively low allowed performance margin when serving a relatively large number of UEs (and / or having a relatively large load). The load of a cell may be the percentage of resource blocks used or the average SINR of communications between the cell and the UEs served by the cell. In the case of unlicensed spectrum, the load may be the channel occupancy seen by a network node or by a UE connected to the network node.

[0120] The CHO Confirmation may contain the HO command for the UE. Thus, the CHO Confirmation may contain the multi-cell target configuration.

[0121] The target cell 420 may know its neighbors, the possibility of establishing a DC connection, and the neighbors of the DC connection based on network high-level configuration, such as Operation, Maintenance and Management (OAM). In addition, as described above, the target cell 420 may know the neighbors of the neighbors using Xn signaling without OAM.

[0122] In other example embodiments, the cell may use a default allowed performance margin. The default margin may also be used for HO to a target cell, i.e., an offset applied to the difference between the serving cell and the target cell when evaluating which cell is stronger. In some example embodiments, the default allowed performance margin may be 3dB.

[0123] If the source cell 405 does not receive the allowed performance margin of the target neighboring cell, the cell 405 sends a query to the target neighboring cell whose allowed performance margin has not been received. For example, if the source cell 405 does not receive the allowed performance margin of the cell 435 at S455, the cell 405 will query the cell 435 for the allowed performance margin of the cell 435 at S460.

[0124] At S465, the cell 435 responds to the query by sending an allowed performance headroom to the source cell 405. The query and signaling of the allowed performance headroom may be performed by the source cell 405 and the cell 435 using XnAP.

[0125] At S470, the source cell 405 sends a CHO command to the UE 402. The command indicates the configuration of the first target configuration 410 and contains the allowed performance margin of the cell 435 on the frequency f1.

[0126] At S475 , the UE 402 evaluates the CHO condition of the first target configuration 410 .

[0127] Figure 5 is a flow chart illustrating a method of evaluating CHO conditions according to an example embodiment.

[0128] At S505, UE 402 acquires at least one CHO condition from source cell 405. The at least one CHO condition includes a performance headroom associated with a cell (eg, cell 435) neighboring the target cell.

[0129] At S510, UE 402 performs measurements on the cells indicated in the CHO command. More specifically, UE 402 may perform RSRP and RSRQ measurements on each cell indicated in the CHO command. In some example embodiments, the CHO command identifies the target cell and the conditions to be met. The conditions refer to one or more of the target cells. The UE performs an evaluation on the conditions in the CHO command. FIG. 4A to FIG. 4B In the example of , UE 402 measures RSRP and / or RSRQ of cell 417 , cell 420 , and cell 435 .

[0130] At S515, UE 402 temporarily selects a target configuration for HO based on condition satisfaction. For example, assuming that part of the condition is an A3 event for one of the serving cell and the target configuration cell, when an A3 event occurs for cell 420, UE 402 temporarily selects the first target configuration 410.

[0131] At S525 , the UE 402 determines whether DL transmissions from cells in targets neighboring the selected target are within an allowed performance margin of the UE 402 .

[0132] In some example embodiments, UE 402 measures the RSRP from target cell 430 and the RSRP from cell 435. UE 402 determines a difference between the RSRP from target cell 430 and the RSRP from cell 435. UE 402 then compares the difference to an allowed performance margin associated with target cell 430 and cell 435. If the difference is less than the allowed performance margin, then the DL transmission from cell 435 is within the allowed performance margin.

[0133] If the UE 402 determines that DL transmission from any one of the cells in the target neighboring the selected target is not within the allowed performance margin, the method returns to S510, where the UE 402 performs measurement again.

[0134] The pseudo code of S525 can be:

[0135] For all frequencies f_i contained in the selected target configuration

[0136] Create a list of cells L(f_i) adjacent to the target cell c_target(f_i) on frequency f_i

[0137] For all cells c_neighbor(f_i) in L(f_i)

[0138] Evaluate c_neighbor(f_i) to allow performance margin to c_target(f_i)

[0139] If the UE 402 determines that DL transmissions from cells in the target neighboring the selected target are within the allowed performance margin, the UE 402 performs HO with the selected target (ie, the target configuration 410) at S530.

[0140] exist FIG. 4A to FIG. 4B In the above example, cell 417 has one neighbor using the same frequency, i.e., cell 435, while cell 420 has no neighbors using the same frequency. However, it should be understood that all cells may have neighbors on their frequencies. In a small cell deployment on a given frequency, some cells may have neighbors, while some cells may not have neighbors.

[0141] CIO is a cell-specific offset that is added to the imbalance assessment of the target cell. Take HO event A3 as an example: In 3GPP TS 38.311 Section 5.5.4.4 "Event A3: Neighbor becomes a better offset compared to SpCell", the leave condition occurs when:

[0142] Mn+Ofn+Ocn+Hys<Mp+Ofp+Ocp+Off

[0143] Where Mn is the measurement result of the neighboring cell without considering any offset, Ofn is the measurement object specific offset of the reference signal of the neighboring cell (i.e., offsetMO defined in measObjectNR corresponding to the neighboring cell), Ocn is the cell specific offset of the neighboring cell (i.e., cellIndividualOffset defined in measObjectNR corresponding to the frequency of the neighboring cell) and is set to zero if not configured for the neighboring cell, Mp is the measurement result of SpCell without considering any offset, Ofp is the measurement object specific offset of SpCell (i.e., offsetM defined in measObjectNR corresponding to SpCell) O), Ocp is the cell-specific offset of SpCell (i.e., cellIndividualOffset defined in measObjectNR corresponding to SpCell) and is set to zero if not configured for SpCell, Hys is the hysteresis parameter of the event (i.e., the hysteresis defined for the event in reportConfigNR), Off is the offset parameter of the event (i.e., a3-Offset defined for the event in reportConfigNR), Mn, Mp are expressed in dBm in the case of RSRP, or in dB in the case of RSRQ and RS-SINR, Ofn, Ocn, Ofp, Ocp, Hys, Off are expressed in dB.

[0144] The example embodiment differs from CIO Ocn and Ocp in that the performance margin is not evaluated between the source cell and the target cell of the handover, but rather between the cell of the target HO configuration and any other neighboring cells using the same frequency.

[0145] Aggregate measurement

[0146] In a network with small cells, multi-connectivity may be the default way to operate or configure a UE. Therefore, selecting one target primary cell (PCell) for handover among several cells (i.e., several cells are cells that may be configured for dual connectivity or carrier aggregation (CA) operation, i.e., PSCell or Scell) based on its cell quality and its corresponding potential secondary cell improves the network, respectively. Considering the signal strength / quality of the potential PSCell or SCell in handover may be beneficial for DC or CA operation, where the aggregate performance of the radio link may be more relevant than the signal strength / quality of the individual links.

[0147] According to at least some example embodiments, the system uses aggregate measurements of cells belonging to a target configuration as a condition for performing CHO. The condition of considering parameters (e.g., RSRP) of at least two cells of the same target configuration including multiple cells (e.g., DC and / or CA) may be referred to as an aggregate condition.

[0148] The aggregated measurement will be calculated by the UE using the measurements of the identified target cell.The manner in which the aggregated measurement is formed and applied as an aggregation condition may be signaled.

[0149] Figure 6 A system having at least one target for handover is shown.

[0150] like Figure 6 As shown, UE 602 is in communication with source cell 605. Based on the location of UE 602, UE 602 has a first target configuration 610 for handover.

[0151] The first target configuration 610 includes a cell 617 configured to provide dual connectivity and a cell 620. The cell 617 may operate as a PCell and provide coverage for a primary cell 630. The cell 620 may operate as a PSCell and provide coverage for a primary secondary cell 625.

[0152] Figure 7 is a flow chart illustrating a handover method using aggregated measurements according to an example embodiment.

[0153] In some exemplary implementations, the conditions for performing CHO include aggregate measurements of several cells belonging to the target configuration. This allows selecting a target configuration with better overall performance.

[0154] At S705, the source cell 605 prepares the cell 617 for CHO by generating and sending a CHO request to the cell 617. The CHO request includes a specific configuration (e.g., a DC configuration) and an aggregation condition determined by the source cell 605. The source cell 605 may determine the configuration based on a measurement report from the UE 602. The aggregation condition may include at least one parameter that the UE will use when determining whether to perform CHO, such as a threshold. The aggregation condition may include a selection by a network node of an algorithm that determines how the UE evaluates multiple cells of a target. This set of possible algorithms may be made known to the UE in a standardized manner. For example, the condition - the selection of the algorithm and at least one parameter - is determined by the OAM or source gNB based on UE capabilities, quality of service (QoS) requirements, cell maximum capacity, system load, a subcombination thereof, or a combination thereof. The signaling may include parameters to be used by the algorithm, such as which cells to sum and what margin to apply. The parameters may include RSRP, RSRQ, SINR, a subcombination thereof, or a combination thereof, as measurements from the target cell for CHO. Additionally or alternatively, the parameters may include a listen-before-talk (LBT) failure rate, a received signal strength indicator (RSSI), a channel occupancy (CO), a subcombination thereof, or a combination thereof.

[0155] Example embodiments of algorithms and parameters for aggregation conditions will be referred to Figures 8 to 10 Describe in more detail.

[0156] In other example embodiments, the aggregation condition may be set by the source cell 605 as a default value.

[0157] A more detailed example is described below.

[0158] At S710, cell 617 sends a request to add the cell as a PSCell for CHO to cell 620. At S715, cell 620 confirms that it will be part of the multi-cell target configuration for CHO.

[0159] At S720, the cell 617 sends a CHO confirmation to the source cell 605. The CHO confirmation indicates a DC configuration of the first target configuration 610 identifying the PCell and the PSCell.

[0160] At S725 , the source cell 605 sends a CHO command to the UE 602 to indicate the DC configuration of the target configuration (ie, the configuration of the first target configuration 610 ).

[0161] At S730, UE 602 acquires measurements from cell 617 and cell 620 to determine whether the aggregation condition is satisfied and determines to perform HO to first target configuration 610 when the aggregation condition is satisfied. Example embodiments of measuring the aggregation condition will be referred to below. Figures 8 to 9 Describe in more detail.

[0162] When UE 602 determines that the aggregation condition is met, UE 602 performs access to cell 617 by, for example, using a random access procedure (RACH) or performing RACH-free access. Performing access is sometimes described as synchronizing with the target.

[0163] Figure 8 is a flow chart illustrating a method according to an example embodiment. More specifically, Figure 8 A method of selecting a target by a UE based on aggregation conditions and aggregate measurements is shown.

[0164] At S805, the UE obtains a measurement of a parameter of the aggregation condition from the target cell. For example, the UE obtains RSRP from the target cell. The UE may determine RSRQ, signal to interference and noise ratio (SINR), or both RSRQ and SINR. In some example embodiments, the UE may measure RSRP, RSRQ, SINR, a subcombination thereof, or a combination thereof, as a measurement from the target cell based on the aggregation condition of CHO. Additionally or alternatively, the UE determines LBT failure rate, RSSI, CO, a subcombination thereof, or a combination thereof, as a measurement of the target cell based on the aggregation condition of CHO.

[0165] At S810, the UE aggregates measurements on a per-target basis. More specifically, the UE combines measurements of all cells in the same target configuration. For example, the UE combines (ie, sums) the RSRP of each cell in a single DC target configuration.

[0166] In at least one other example embodiment, the source cell instructs the UE to consider only up to the n strongest cells in the target cells (i.e., as part of the aggregation condition) and the UE determines the aggregate measurement as summing only up to the n strongest cells in the target, n < the number of cells in the target. If n is 1, the aggregate measurement is equivalent to selecting the strength of the strongest cell. In other example embodiments, the source cell instructs the UE to sum the RSRP from each cell or the n strongest RSRPs (i.e., as part of the aggregation condition), and the UE determines the measurement by combining the RSRP of each cell in the first target or combining the nth strongest RSRP of each cell in the first target and comparing it with the sum of the RSRPs of the second target (each cell in the second target or the nth strongest in the second target based on the aggregation condition), or comparing it with the sum of the configuration including the source cell (each cell in the configuration including the source cell or the nth strongest in the configuration including the source cell). For example, if the aggregation condition is to sum the n strongest RSRPs of the first target configuration and compare the sum with the n strongest RSRPs of the second target configuration and HO based on which combination is the largest and above a threshold, the UE sums the n strongest RSRPs of the first target configuration and compares the sum with the sum of the n strongest RSRPs of the second target configuration. The UE then compares the larger sum with the threshold, and if the larger sum is greater than the threshold (e.g., the RSRP of the source cell plus the offset value), the UE performs HO with the target cell associated with the target configuration with the larger sum.

[0167] At S815 , the UE selects a target configuration based on the aggregated HO condition and the aggregated measurement of each target configuration.

[0168] Fig. 9 Used to illustrate an example embodiment of aggregating measurements on a per-goal basis. Fig. 9 A system with two target configurations for switching is shown.

[0169] like Fig. 9 As shown, UE 902 is in communication with source cell 905. Based on the location of UE 902, UE 902 has a first target configuration 910 for handover and a second target configuration 915 for handover.

[0170] The first target configuration 910 includes a cell 917 configured to provide dual connectivity and a cell 920. The cell 917 may operate as a primary node and provide a coverage primary cell 925. The cell 920 may operate as a secondary node and provide a primary and secondary coverage area 930. Although the coverage secondary cell 930 is shown as being completely within the primary coverage area 925, example embodiments are not limited thereto.

[0171] The second target configuration 915 includes a cell 935 configured to provide dual connectivity and a cell 940. The cell 935 may operate as a primary node and provide a primary coverage area 945. The cell 940 may operate as a secondary node and provide a primary and secondary coverage area 950.

[0172] The first target configuration 910 and the second target configuration 915 are configured to provide dual connectivity to the UE.

[0173] In some example embodiments, the source cell 905 defines the HO condition as event A3. Assuming that the first target configuration 910 is in a single target handover scenario, the handover triggering condition is satisfied in the following cases:

[0174] Strength (source cell 905) < Strength (cell 917) - O

[0175] Where O is the offset. For multi-cell targets, aggregate measurements can be introduced by scaling the offset so that instead of considering a single target cell, the sum of all target cells is considered. Therefore, in the above equation for the traditional A3 event, the offset O is replaced by the scaled offset:

[0176] O_scaled = O + intensity (cell 917) - ∑ intensity (cell of target configuration 910)

[0177] This type of scaled offset uses aggregate measurements from multiple cells of the target to produce an aggregate condition:

[0178] Strength (source cell 905) < Strength (cell 917) - O_scaled, which is equivalent to

[0179] Strength (source cell 905) <∑ Strength (cell of target configuration 910) - O

[0180] Under the above aggregation conditions, the sum is calculated by the UE over all cells of the first target configuration 910 .

[0181] In other example embodiments, the cells of the target configuration may be sorted by the UE according to strength, and the UE may add the n highest strengths, where n is less than the number of cells in the target configuration. If n is 1, the UE selects the cell with the highest strength.

[0182] The strength of the cell may be RSRP, RSRQ, SINR, LBT failure rate, CO, RSSI, a subcombination thereof, or a combination thereof, but is not limited thereto.

[0183] Example embodiments also provide for the use of aggregated measurements utilizing more than one target configuration for CHO. In the following description:

[0184] M = ∑ strength (cell of target configuration)

[0185] use Fig. 9 As an example embodiment, UE 902 obtains measurements from first target configuration 910 and second target configuration 915 as follows:

[0186] First target configuration 910:

[0187] PCell (cell 917), RSRP = -95dBm;

[0188] PSCell (cell 920), RSRP = -80dBm;

[0189] M1=-79.9dBm

[0190] Second target configuration 915:

[0191] PCell (cell 935), RSRP = -91 dBm;

[0192] PSCell (cell 940), RSRP = -100 dBm;

[0193] M2=-90.5dBm

[0194] Assume that the strength of the source cell 905 is -95dBm and the offset O is 3dB. The aggregation condition with aggregated measurement is triggered in the following cases

[0195] Strength(service)<∑strength(target configured cell)-O.

[0196] For the first target configuration 910, the aggregation condition evaluates to:

[0197] -95<-79.9-3

[0198] For the second target configuration 915, the aggregation condition evaluates to:

[0199] -95>-90.5-3.

[0200] Therefore, in the above example embodiment, the aggregation condition will be satisfied for the first target configuration 910, but not for the second target configuration 915. In contrast, in a conventional scenario, the UE will select the cell 935 of the second target configuration 915 (first target configuration 910: -95>-95-3; target configuration 915: -95<-91-3).

[0201] Fig.10 Other example embodiments are used to illustrate aggregating measurements on a per-goal basis. Fig.10 A system with two target configurations for switching is shown.

[0202] like Fig.10As shown, UE 1002 is in communication with source cell 1005. Based on the location of UE 1002, UE 1002 has a first target configuration 1010 for handover and a second target configuration 1015 for handover.

[0203] The first target configuration 1010 includes a cell 1017 configured to provide dual connectivity and a cell 1020. The cell 1017 may operate as a primary node and provide a coverage primary cell 1025. The cell 1020 may operate as a secondary node and provide a primary and secondary coverage area 1030. Although the coverage secondary cell 1030 is shown as being completely within the primary coverage area 1025, example embodiments are not limited thereto.

[0204] The second target configuration 1015 includes a cell 1035 configured to provide dual connectivity and a cell 1040. The cell 1035 may operate as a primary node and provide a primary coverage area 1045. The cell 1040 may operate as a secondary node and provide a primary and secondary coverage area 1050.

[0205] The first target configuration 910 and the second target configuration 915 are not configured to provide dual connectivity to the UE. However, the cell 1017 and the cell 1035 use the same frequency f1, and the cell 1020 and the cell 1040 use the same frequency f2.

[0206] UE 1002 evaluates the handover conditions between source cell 1005 and the target cell of handover 1017 and 1050. In an example embodiment, the UE scales the handover offset of the target cell of handover 1017 and 1050 based on aggregated cell measurements. The following terminology is used:

[0207] Ms: Measurement of the serving cell 1005 by UE 1002 .

[0208] Mc1: Measurement of the neighboring cell 1017 (PCell) by the UE 1002.

[0209] Mc2: Measurement of the neighboring cell 1020 (PSCell) by the UE 1002 which may be configured to perform DC operation with the neighboring cell 1017 .

[0210] Mc3: Measurement of the neighboring cell 1035 (PCell) by the UE 1002 which may be configured for DC operation with the neighboring cell 1040 (PSCell).

[0211] For A3 events:

[0212] Ms <Mc1–O

[0213] Ms <Mc3–O

[0214] UE 1002 is configured to determine A3 events using aggregated cell measurements as follows:

[0215] Ms <Mc1–Oscaled1

[0216] Ms <Mc3–Oscaled2

[0217] Where Oscaled1 is the scaled offset of offset O of target cell 1017 , and Oscaled2 is the scaled offset of offset O of target cell 1035 .

[0218] UE 1002 uses the abbreviation of ∑strength(target configured cell)=∑target cell to determine the scaling offset Oscaled1 and scaling offset Oscaled2 as follows:

[0219]

[0220]

[0221] An example embodiment of a determination performed by UE 1002 to select a target cell for handover using an offset O of 3 dB is provided below.

[0222] Example 1

[0223] If ∑ cell target 1 = sum(cell 1017, cell 1020) = ∑ cell target 2 = sum(cell 1035, cell 1040)

[0224] Then Oscaled1=Oscaled2=O=3dB.

[0225] Therefore, no scaling with aggregated cell strength occurs in Example 1.

[0226] Example 2

[0227] If ∑ cell target 1 = sum(cell 1017, cell 1020) = 1.2*∑ cell target 2 = 1.2*sum(c3, c4)

[0228] but

[0229] Oscaled1=3-0.7918=2.2

[0230] and

[0231] Oscaled2=3+0.7918=3.7918dB.

[0232] As a result, in Example 2, UE 1002 determines that handover to cell 1035 is more difficult than handover to cell 1017.

[0233] In some example embodiments, UE 1002 limits the scaling of offset O as follows:

[0234]

[0235] Where maxScaling is the maximum scaling offset and minScaling is the minimum scaling offset.

[0236] The minScaling and maxScaling may be set by OAM and adjusted to avoid too large a reception strength imbalance between neighboring cells exceeding a threshold level when selecting a cell based on aggregate measurements.

[0237] In some example embodiments, the maximum scaling offset maxScaling is 1.5 dB and the minimum scaling offset minScaling is -1.5 dB. Using 1.5 dB and -1.5 dB as the maximum and minimum scaling offsets, respectively, and using the values ​​from Example 2, UE 1002 determines the scaling offset Oscaled1 as:

[0238] Oscaled1=O-max(min(0.79, 1.5), -1.5)=3-0.79.

[0239] An example is provided below where the UE 1002 uses the maximum and minimum scaling offsets as the max() values.

[0240] if

[0241] but

[0242] Oscaled1=O-max(min(3,1.5),-1.5)=3-1.5=1.5

[0243] and

[0244] Oscaled2=O-max(min(3,-3),-1.5)=3+1.5=4.5 Combining multiple conditions

[0245] In some example embodiments, the source cell may instruct the UE to combine multiple Ai events and use the combined Ai event as the CHO condition. The Ai event includes any one of the A1-A6 events described in 3GPP 36.331 Release 15.

[0246] In some example embodiments, if trigger condition A4 of the PCell of the target configuration and trigger condition A4 of the PSCell of the target configuration are both satisfied, the source cell may instruct the UE to select the target configuration in the CHO command.

[0247] In other example embodiments, the source cell may instruct the UE in the CHO command to compare events of the same type from multiple target configurations. The source cell may instruct the UE to monitor A3 events from the PCell of the first target configuration and monitor A3 events from the PCell of the second target configuration. If the A3 event occurs for both the first target configuration and the second target configuration, the UE selects the first target configuration for HO if the sum of the strengths of all cells of the first target configuration is greater than the sum of the strengths of all cells of the second target configuration under certain circumstances. In this example, the sum of the strengths of the cells is evaluated after the first condition of the A3 event is met to ensure that all cells of the target configuration can communicate with the UE.

[0248] In other example embodiments, the source cell may instruct the UE in the CHO command to evaluate the A3 event and another metric, such as a lost discovery reference signal (DRS)-count (for NR unauthorized). If the A3 event occurs for both the first target configuration and the second target configuration, the UE is instructed to select a target configuration based on the lost DRS count of the PCell of the first target configuration and the second target configuration, respectively. If the lost DRS count of the PCell of the first target configuration is less than the lost DRS count of the PCell of the second target configuration, the UE selects the PCell of the first target configuration for switching.

[0249] Fig.11 Example embodiments of a node such as a gNB are shown.

[0250] As shown in the figure, the gNB includes: a memory 1140; a processor 1120 connected to the memory 1140; various interfaces 1160 connected to the processor 1120; and one or more antennas or antenna panels 1165 connected to the various interfaces 1160. The various interfaces 1160 and the antenna 1165 may constitute a transceiver, and the transceiver is used to send / receive data to / from the UE via multiple wireless beams or to / from one or more TRPs. It should be understood that according to the implementation of the gNB, the gNB may include more than Fig.11 Many more components are shown. However, for purposes of disclosing illustrative example embodiments, it is not necessary to show all of these typically conventional components.

[0251] The memory 1140 may be a computer-readable storage medium, typically including a random access memory (RAM), a read-only memory (ROM), and / or a permanent mass storage device, such as a disk drive. The memory 1140 also stores an operating system and any other routines / modules / applications for providing the functions of the node to be executed by the processor 1120 (e.g., the functions of the node, the method according to the example embodiment, etc.). These software components may also be loaded into the memory 1140 from a separate computer-readable storage medium using a drive mechanism (not shown). Such a separate computer-readable storage medium may include a disk, a tape, a DVD / CD-ROM drive, a memory card, or other similar computer-readable storage medium (not shown). In some example embodiments, the software components may be loaded into the memory 1140 via one of the various interfaces 1160 rather than via a computer-readable storage medium.

[0252] The processor 1120 may be configured to execute instructions of a computer program by performing arithmetic, logical, and input / output operations of the system. The instructions may be provided to the processor 1120 by the memory 1140 .

[0253] The various interfaces 1160 may include components that interface the processor 1120 with an antenna 1165 or other input / output components. It will be appreciated that the various interfaces 1160 and the programs stored in the memory 1140 to address the specific functions of the node will vary depending on the implementation of the node.

[0254] The interface 1160 may also include one or more user input devices (eg, keyboard, keypad, mouse, etc.) and user output devices (eg, display, speaker, etc.).

[0255] Although not discussed in detail in this article, Fig.11 The illustrated configuration may be used to implement a TRP, a gNB, other radio access and backhaul network elements, a central unit (CU), an eNB, an ng-eNB, etc. In this regard, for example, the memory 1140 may store an operating system and any other routines / modules / applications for providing functionality of the TRP, gNB, etc. to be executed by the processor 1120 (e.g., functionality of these elements, methods according to example embodiments, etc.).

[0256] Fig.13 An example embodiment of a user equipment (UE) is shown.

[0257] As shown in the figure, the UE includes: a memory 1340; a processor 1320 connected to the memory 1340; various interfaces 1360 connected to the processor 1320; and one or more antennas or antenna panels 1365 connected to the various interfaces 1360. The various interfaces 1360 and the antenna 1365 may constitute a transceiver, and the transceiver is used to send / receive data to / from a network node via multiple wireless beams. It should be understood that according to the implementation of the UE, the UE may include more than Fig.13 Many more components are shown. However, for purposes of disclosing illustrative example embodiments, it is not necessary to show all of these typically conventional components.

[0258] The memory 1340 may be a computer-readable storage medium, typically including a random access memory (RAM), a read-only memory (ROM), and / or a permanent mass storage device, such as a disk drive. The memory 1340 also stores an operating system and any other routines / modules / applications for providing the functions of the UE to be executed by the processor 1320 (e.g., the functions of the UE, the methods according to the example embodiments, etc.). These software components may also be loaded into the memory 1340 from a separate computer-readable storage medium using a drive mechanism (not shown). Such a separate computer-readable storage medium may include a disk, a tape, a DVD / CD-ROM drive, a memory card, or other similar computer-readable storage medium (not shown). In some example embodiments, the software components may be loaded into the memory 1340 via one of the various interfaces 1360 rather than via a computer-readable storage medium.

[0259] The processor 1320 may be configured to execute instructions of a computer program by performing arithmetic, logical, and input / output operations of the system. The instructions may be provided to the processor 1320 by the memory 1340 .

[0260] The various interfaces 1360 may include components that interface the processor 1320 with an antenna 1365 or other input / output components. It should be understood that the various interfaces 1360 and the programs stored in the memory 1340 to address the specific functions of the node will vary depending on the implementation of the node.

[0261] Interface 1360 may also include one or more user input devices (eg, keyboard, keypad, mouse, etc.) and user output devices (eg, display, speaker, etc.).

[0262] Although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0263] When an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element or there may be intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent to" versus "directly adjacent to," etc.).

[0264] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are also intended to include plural forms unless the context clearly indicates otherwise. It is further understood that the terms "comprise", "include", "includes" and / or "comprising)" when used herein specify the presence of the features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof.

[0265] It should also be noted that in some alternative implementations, the functions / actions noted may not occur in the order noted in the figures. For example, two figures shown in succession may actually be executed substantially simultaneously or may sometimes be executed in reverse order, depending on the functions / actions involved.

[0266] Specific details are provided in the following description to provide a thorough understanding of the example embodiments. However, one of ordinary skill in the art will appreciate that the example embodiments may be practiced without these specific details. For example, systems may be shown in block diagrams so as not to obscure the example embodiments with unnecessary detail. In other cases, well-known processes, structures, and techniques may be shown without unnecessary detail to avoid obscuring the example embodiments.

[0267] As discussed herein, the illustrative embodiments will be described with reference to acts and symbolic representations of operations (e.g., in the form of flow charts, flowcharts, data flow diagrams, structure diagrams, block diagrams, etc.), which operations may be implemented as program modules or functional processes, which include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types, and may be implemented using existing hardware, such as at existing user equipment, base stations, eNBs, RRHs, gNBs, femto base stations, network controllers, computers, central units (CUs), ng-eNBs, WLAN access points (APs), WLAN stations (STAs), other radio access or backhaul network elements, etc. Such existing hardware may be processing or control circuitry such as, but not limited to, one or more processors, one or more central processing units (CPUs), one or more controllers, one or more arithmetic logic units (ALUs), one or more digital signal processors (DSPs), one or more microcomputers, one or more field programmable gate arrays (FPGAs), one or more systems on chips (SoCs), one or more programmable logic units (PLUs), one or more microprocessors, one or more application specific integrated circuits (ASICs), or any other device capable of responding to and executing instructions in a defined manner.

[0268] Although a flowchart may describe operations as a sequential process, many operations may be performed in parallel, concurrently, or simultaneously. In addition, the order of operations may be rearranged. A process may terminate when its operations are completed, but may also have additional steps not included in the diagram. A process may correspond to a method, function, procedure, subroutine, subprogram, etc. When a process corresponds to a function, its termination may correspond to a function returning to the calling function or the main function.

[0269] As disclosed herein, the term "storage medium", "computer-readable storage medium" or "non-transitory computer-readable storage medium" may refer to one or more devices for storing data, including read-only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage media, optical storage media, flash memory devices and / or other tangible machine-readable media for storing information. The term "computer-readable medium" may include, but is not limited to, portable or fixed storage devices, optical storage devices, and various other media capable of storing, containing or carrying (multiple) instructions and / or data.

[0270] In addition, the example embodiments may be implemented by hardware, software, firmware, middleware, microcode, hardware description language, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments that perform the necessary tasks may be stored in a machine or computer readable medium, such as a computer readable storage medium. When implemented in software, one or more processors will perform the necessary tasks. For example, as described above, according to one or more example embodiments, at least one memory may include or store computer program code, and at least one memory and computer program code may be configured to cause a network element or network device to perform the necessary tasks together with at least one processor. In addition, the processor, memory, and example algorithm encoded as a computer program code are used as components for providing or causing the execution of the operations discussed herein.

[0271] The code segment of a computer program code can represent any combination of a process, function, subprogram, program, routine, subroutine, module, software package, class, or instruction, data structure, or program statement. A code segment can be coupled to another code segment or hardware circuit by transmitting and / or receiving information, data, independent variables, parameters, or memory contents. Information, independent variables, parameters, data, etc. can be transmitted, forwarded, or transmitted via any suitable technology, including memory sharing, message passing, token passing, network transmission, etc.

[0272] As used herein, the terms "including" and / or "having" are defined as comprising (i.e., open language). As used herein, the term "coupled" is defined as connected, but not necessarily directly and not necessarily mechanically. Terms derived from the word "indicate" (e.g., "instructions" and "directions") are intended to cover all of the various techniques that can be used to transmit or reference the indicated object / information. Some (but not all) examples of techniques that can be used to transmit or reference the indicated object / information include transmission of the indicated object / information, transmission of an identifier of the indicated object / information, transmission of information used to generate the indicated object / information, transmission of a segment or portion of the indicated object / information, transmission of a derivative of the indicated object / information, and transmission of a symbol representing the indicated object / information.

[0273] According to example embodiments, user equipment, base stations, eNBs, RRHs, gNBs, femto base stations, network controllers, computers, central units (CUs), ng-eNBs, other radio access or backhaul network elements, etc. may be (or include) hardware, firmware, hardware executing software, or any combination thereof. Such hardware may include processing or control circuit systems such as, but not limited to, one or more processors, one or more CPUs, one or more controllers, one or more ALUs, one or more DSPs, one or more microcomputers, one or more FPGAs, one or more SoCs, one or more PLUs, one or more microprocessors, one or more ASICs, or any other device capable of responding to and executing instructions in a defined manner.

[0274] Benefits, other advantages, and solutions to problems have been described above with respect to specific embodiments of the present invention. However, benefits, advantages, solutions to problems, and any element(s) that may cause or lead to such benefits, advantages, or solutions, or that cause such benefits, advantages, or solutions to become more apparent, should not be construed as key, required, or essential features or elements of any or all claims.

Claims

1. A user equipment UE, include: at least one processor; as well as at least one memory including computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the UE to: obtaining a conditional handover command, the conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance headroom, each performance headroom of the at least one performance headroom being associated with a cell in the multi-cell target that is adjacent to the first cell, determining whether to initiate a handover to the first cell based on the at least one performance headroom, and Based on the determination of whether to initiate the handover, sending data to the first cell, The at least one performance margin is an allowed signal offset for the first frequency, and the allowed signal offset is an allowed difference between a measured signal strength of the first cell and a measured signal strength of the cell adjacent to the first cell.

2. The UE according to claim 1, wherein the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: measuring at least one signal from the first cell, determining whether a condition for the conditional switching is met based on the at least one signal measured from the first cell, and If the condition is determined to be satisfied, the first cell is selected as a handover target cell.

3. The UE according to claim 2, wherein the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: measuring at least one signal from the source cell, and It is determined whether the condition for the conditional handover is met based on the at least one measured signal from the source cell and the at least one measured signal from the first cell.

4. The UE according to claim 3, wherein the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: measuring at least one signal from the cell neighboring the first cell, Whether to initiate the handover to the first cell is determined based on the at least one performance headroom, the at least one measured signal from the first cell, and the at least one measured signal from the cells neighboring the first cell.

5. The UE according to claim 4, wherein the at least one memory and the computer program code are further configured to, together with the at least one processor, cause the UE to: The handover to the first cell is initiated when a difference between the at least one signal measured from the first cell and the at least one signal measured from the cell neighboring the first cell is less than the performance margin.

6. A method of communication, include: Obtain a conditional handover command, the conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance headroom, each performance headroom of the at least one performance headroom being associated with a cell in the multi-cell target that is adjacent to the first cell; determining whether to initiate a handover to the first cell based on the at least one performance headroom; as well as Based on the determination of whether to initiate the handover, sending data to the first cell, The at least one performance margin is an allowed signal offset for the first frequency, and the allowed signal offset is an allowed difference between a measured signal strength of the first cell and a measured signal strength of the cell adjacent to the first cell.

7. The method according to claim 6, further comprising: include: measuring at least one signal from the first cell; determining whether a condition for the conditional switching is met based on the at least one signal measured from the first cell; as well as If the condition is determined to be satisfied, the first cell is selected as a handover target cell.

8. The method according to claim 7, further comprising: include: and measuring at least one signal from the source cell, wherein determining whether the condition for the conditional switching is satisfied is based on the at least one signal measured from the source cell and the at least one signal measured from the first cell.

9. The method according to claim 8, further comprising: include: measuring at least one signal from the cell neighboring the first cell, wherein determining whether to initiate the handover comprises, Whether to initiate the handover to the first cell is determined based on the at least one performance headroom, the at least one measured signal from the first cell, and the at least one measured signal from the cells neighboring the first cell.

10. The method according to claim 9, further comprising: include: The handover to the first cell is initiated when a difference between the at least one signal measured from the first cell and the at least one signal measured from the cell neighboring the first cell is less than the performance margin.

11. A non-transitory computer-readable storage medium storing computer-readable instructions, which, when executed at a user equipment (UE), causes the UE to perform a method, the method include: Obtain a conditional handover command, the conditional handover command indicating a multi-cell target for handover from a source cell and at least one performance headroom, each performance headroom of the at least one performance headroom being associated with a cell in the multi-cell target that is adjacent to the first cell; determining whether to initiate a handover to the first cell based on the at least one performance headroom; as well as Based on the determination of whether to initiate the handover, sending data to the first cell, The at least one performance margin is an allowed signal offset for the first frequency, and the allowed signal offset is an allowed difference between a measured signal strength of the first cell and a measured signal strength of the cell adjacent to the first cell.

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