User equipment supporting conditional handover to a cellular network cell and cellular network supporting conditional handover

Abstract

Embodiments of the user equipment support conditional handover to one or more cells of a cellular network. The user equipment is configured to receive configuration data from the cellular network. The configuration data indicates conditions for triggering conditional handover to any target cell for multiple target cells of the cellular network. The user equipment is also configured to check the conditions for applicability and trigger the conditional handover if applicable.

Description

Technical Field

[0001] The present application relates to handover concepts in cellular networks. The present application relates to user equipment supporting conditional handover to a cellular network cell. The present application relates to a cellular network supporting conditional handover. The present application relates to conditional handover of a base station for an in-vehicle network and a mobile. Background Art

[0002] Scenario description

[0003] Non-terrestrial networks provide wide area coverage for, e.g., stationary or mobile devices. For example, in the case of low earth orbit (LEO) satellites, a base station (BS) or next generation NodeB (gNB) (in the case of 5G) can move at high speed on a determined route over the coverage area. For example, a LEO satellite can provide coverage for a certain area until, for example, a handover to the next moving satellite occurs. For example, in the case where the devices provide connectivity for mobile devices (such as trains or airplanes), the user equipment (UE) as well as the gNB will move, making the mobility process, for example, more important. It should be noted that the base station can also be an LTE base station, referred to as an enhanced NodeB (eNB).

[0004] Latest Conditional Switches

[0005] Conditional Handover (CHO) is discussed for 5G mobility enhancement. For example, the goal of CHO is to improve the mobility robustness of the handover process. For example, conditional handover aims to avoid radio link failure (RLF), which is caused by, for example, late measurement reports that may not reach the network, and / or even when the measurement report is received and the network decides to perform the handover, the handover command does not reach the UE before the RLF occurs and the UE starts the reestablishment process.

[0006] For example, FIG1 shows an exemplary critical failure scenario that CHO may avoid.

[0007] For example, one solution to improve mobility robustness is conditional handover (CHO). For example, in conditional handover, the network configures trigger conditions for the UE. For example, based on the configuration obtained by the network, the UE can decide when the handover can be performed. When the conditions are met, the UE performs the handover without any other commands from the network. The advantages of this process are, for example, that a handover (HO) command can be provided to the UE at an earlier stage (for example, before the radio conditions may deteriorate), which can increase the possibility of successfully transmitting the message. In addition, such CHO enables, for example, the HO to be performed at an earlier moment, although the current link can still support good link quality. If the HO conditions are set accordingly, this can enable the UE to experience continuous quality of service (QoS) in terms of delay, reliability and throughput, for example, while moving through the network.

[0008] Figure 2 An exemplary latest CHO is shown.

[0009] There is a need to further enhance mobility robustness in cellular networks. Summary of the invention

[0010] Embodiments of the user equipment support conditional handover to one or more cells of a cellular network.

[0011] The user equipment is configured to receive configuration data from a cellular network. The configuration data indicates conditions for triggering conditional handover to any target cell for a plurality of target cells of the cellular network.

[0012] The user equipment is further configured to check the conditions with respect to applicability and, if applicable, trigger a conditional handover. In other words, the configuration data relates to a plurality of target cells of the cellular network, which target cells are arranged, for example (but necessarily) along an estimated future route of the UE, and for each of the plurality of target cells, the configuration data may indicate one or more associated conditions, the applicability of which should be continuously determined by the UE, and if any one of them (or a combination of them, such as all) is met, then this condition should trigger the UE to start CHO to the respective target cell. Thus, the configuration data may be structured into parts, each part relating to a certain target cell and comprising one or more conditions associated with the respective target cell.

[0013] In a preferred embodiment, the user equipment is configured to: after completing the conditional handover (or in other words, in response to having completed the handover to a certain target cell), delete the first part of the configuration data and retain the second part of the configuration data, for example, delete the first part related to the completed conditional handover (or respectively related to the corresponding target cell). As a result, the network does not need to update the configuration data of the UE after any CHO has been performed, and the UE is then exempted from checking the conditions related to the target cell for which the CHO has been completed. In addition, it may not be desirable for the UE to switch back to the target cell in which the CHO has occurred once among the multiple target cells through CHO.

[0014] The cellular network may act synchronously, i.e. it may modify the configuration data synchronously such that the configuration data remain equal on both sides (at the UE and at the network side). More precisely, the network may retain only those target cells prepared for CHO to which the updated / synchronized configuration data still relates, e.g. by assigning corresponding CHO details to the UE.

[0015] For example, modifying the configuration data may include a first portion of the configuration data relating to completed and / or concluded handovers being removed from the configuration data, while a second portion of the configuration data relating to uncompleted or unconcluded handovers may be retained.

[0016] According to an embodiment, the user equipment is therefore configured to continue checking after the first triggering of a conditional handover. In other words, the configuration data relates to a plurality of target cells of the cellular network, which are considered to form useful target cells, so as to perform CHO even sequentially, one after another, rather than purely alternately with each other, whereby the UE continues to check the conditions of the configuration data after the first CHO triggered based on these conditions.

[0017] According to an embodiment, the first trigger involves a conditional handover from a first cell to a second cell, and the continued checking includes checking conditions for a conditional handover from the second cell to the first cell (i.e., back to the first cell, which is then also a cell to which the configuration data relates in the target cell) and / or any other cell outside the target cell. It should be noted that, for example, the conditions from the first cell to the second cell may be different from the conditions from the second cell to the first cell. In this way, handback may be made possible, for example, for a situation where the UE makes a U-turn and traverses the estimated future route in reverse.

[0018] In addition to checking trigger conditions related to conditional switching, for example, the UE may also check unconfigured target cells, i.e., the usefulness of switching to any target cell that does not belong to the multiple target cells involved in the configuration data may be checked, and if the unconfigured target cell is a suitable candidate (e.g., detected by triggering a measurement report or a different kind of configured / preconfigured trigger), the source cell is notified of the suitable switching candidate (e.g., using a measurement report or a report requiring reconfiguration of the conditional switching configuration). In this way, a switch to a suitable cell may be initiated. In the case of a conditional switch requiring addition to the target cell involved in the configuration data, the network or the current serving cell may send new configuration data or an update to the existing configuration to the UE. It is also possible to initiate a normal switch, in which the serving cell prepares for a switch to a target cell that has not yet been foreseen.

[0019] According to an embodiment, the user equipment is configured to trigger conditional handover available to the user equipment only within a limited time interval indicated in the configuration data. In other words, the conditional handover to a certain target cell can be regulated by the configuration data at least in part according to the time interval, during which the conditional handover is the only one allowed. Therefore, the UE will have to check whether the current time falls within the time interval, thereby checking whether the CHO to the corresponding target cell is available. For more than one target cell or all target cells involved in the configuration data, such a time interval can be given in the configuration data.

[0020] According to an embodiment, the configuration data includes more than one finite time interval and / or periodic time interval assigned to different target cells. For example, when using satellite target cells, periodic time intervals (e.g., a cyclic sequence of time intervals) may be defined, wherein the periodicity of the time intervals is related to the orbital periodicity of the satellite target cells.

[0021] According to an embodiment, the conditions (or triggering conditions) for triggering may include service-dependent triggers, such as URLLC deletion, ignoring common configurations or cells that do not support URLLC services, or reducing the priority of common configurations or cells that do not support URLLC services. In other words, the conditions defined in the configuration data may prefer certain target cells over other target cells (e.g., target cells with different service capabilities), which may depend on the characteristics of the UE. In other words, the configuration data can be designed so that: in the case where two or more target cells can be used to trigger CHO to them according to a first target cell separate condition set for each of these target cells, additional condition data describing the target cell in the configuration data can be used to select one of the available target cells, wherein the additional condition data describes the target cell technology.

[0022] The trigger may also be a policy dependent trigger, e.g. based on a charging model, where a particular UE may not be allowed to access a certain technology, e.g. a UE with a cheaper modem or a free customer may not be able to access multi-RAT eNB / gNB. That is, for example, the UE must meet certain technology requirements for CHO to certain target cells according to conditions defined in the configuration data. Even in other words, the configuration data may be designed such that in the case where two or more target cells are available for triggering CHO thereto according to a first target cell separate condition set for each of these target cells, additional condition data in the configuration data describing the target cell may be used to select one of the available target cells, wherein the additional condition data describes the target cell technology.

[0023] The trigger may also be a handover failure trigger, where the UE may track the history of past unsuccessful handovers and may reduce the priority of handovers to target cells that have failed in the past and / or are overloaded and / or have refused handovers in the past. This may also be a trigger signaled by a cellular network, such as a base station and / or a cell sending a trigger and adding a probability of success based on past analysis. This may also be included in configuration data signaled by a cellular network, such as a base station and / or a cell sending configuration data, where the probability of success based on past analysis is attached to the trigger condition. In other words, the configuration data may be designed so that: in the case where two or more target cells are available for triggering CHO to them according to a first target cell separate condition set for each of these target cells, additional condition data in the configuration data that prioritizes or ranks the target cells with each other may be used to select one of the available target cells, where the additional condition data ranks the target cells according to the probability of handover success.

[0024] In a preferred embodiment, the configuration data regarding the preferred target cell and / or regarding the target cell with the first (primary) preference comprises alternate different trigger conditions than the configuration data regarding the alternate target cell and / or regarding the target cell with the second (secondary) preference.

[0025] In addition, the triggering conditions of the backup target cell configuration data and / or the configuration data of the target cell with the second preference include an initial triggering condition, according to which the handover to the preferred target cell and / or the target cell with the first preference has failed, that is, one or more conditions for CHO to the preferred target cell have been applied, but the handover ultimately failed.

[0026] For example, this grouping or ranking can be done so that

[0027] ·Prefer cells that ensure service continuity, and / or

[0028] Prioritize cells with more bandwidth, and / or

[0029] Prefer 5G / LTE over 3G, GSM or other radio access technologies (RATs), and / or

[0030] ·Prefer cells with less occupancy or less communication resource pressure, and / or

[0031] Prefer small cells or cells operating at mmWave to macro cells with wider coverage that may operate at lower frequencies, and / or

[0032] • Prefer unlicensed cells to licensed cells.

[0033] These preferences may also be reversed, depending on, for example, policy, charging model, modem type, or the service being run.

[0034] In a preferred embodiment, the configuration data includes information about the order of target cells on which the user equipment intends to perform conditional handover. For example, the UE may be expected to check whether CHO to a certain target cell results in the condition that the target cell becomes the nth target cell among the multiple target cells to which the configuration data relates (for which CHO is initiated). If not, the target cell is not available for CHO.

[0035] In a preferred embodiment, the user equipment is configured to update the configuration data according to the configuration update received from the cellular network. That is, the new configuration data is not sent to the UE in a self-contained manner (i.e. completely new) but as a difference from the current version of the configuration data at the UE.

[0036] In a preferred embodiment, the user equipment is configured to receive configuration data comprising a first part and a second part. The first part of the configuration data (comprising group-specific parameters or common parameters, such as LEO satellite routes) is received via broadcast or groupcast or multicast transmission to reduce signaling overhead, and the second part of the configuration data (comprising user-specific parameters or individual parameters) is received via unicast transmission.

[0037] The first part of the configuration data may be overwritten by the second part of the configuration data, ie the common parameters may be overwritten by the individual parameters.

[0038] According to an embodiment, the user equipment is configured to trigger an update of the configuration data from the serving cell by sending a report (eg a measurement report) to the actual serving cell and / or to the new serving cell.

[0039] If the user equipment is still connected to the serving cell, sending a report to the actual serving cell can inform the actual serving cell when the user equipment cannot perform a handover to one or more potential target cells, while sending a report to the new serving cell after the user equipment loses and reconnects to the cellular network can inform the new serving cell of the erroneous handover configuration.

[0040] The user equipment may also be triggered by the serving cell or the new serving cell to provide measurement reports and / or measurement data, giving information about which triggers led to one or more previous handovers.

[0041] The measurement report is provided from the UE to the cellular network and it may contain several time-related and location-related information to improve the information about the expected location and expected time of arrival of the UE.

[0042] According to an embodiment, the user equipment is configured to exchange context information with other nodes of the cellular network, which may involve a transceiver and may be particularly explained in conjunction with a user equipment (UE). The embodiments are not limited to UEs, but rather relate to, but are not limited to, other types of transmitters or transceivers, such as transceivers including any item and / or device (e.g., a sensor or actuator) having a network connection, such that the item and / or device can communicate using a wireless communication network.

[0043] For example, a mobile or fixed base station may include any transmit / receive point (TRP) to enable an item or device having a network connection for communicating using a wireless communication network to communicate.

[0044] Another embodiment of the cellular network supports conditional switching and is configured to, for one or more predetermined user equipment, preemptively prepare for conditional switching of the user equipment to one or more corresponding target cells identified by a cell identifier for each of one or more target cells of the cellular network of the one or more predetermined user equipment.

[0045] The cellular network is further configured to send configuration data to the user equipment, the configuration data describing, for each cell, conditions for triggering a handover to the respective cell.

[0046] The cellular network preemptively prepares the handover of the user equipment of the present invention to the corresponding cell, or only prepares for future handover to the corresponding cell that may be performed by the user equipment. The preemptive preparation may involve assigning one of the available IDs to the user equipment. For example, the ID is included in the user equipment separate part of the configuration data.

[0047] For example, preemptive preparation can include

[0048] Transfer and storage of user context, such as RRC context, and / or

[0049] A reserved user ID, such as RNTI, and / or

[0050] · Reserve RACH preamble, and / or

[0051] Reserve resources, and / or

[0052] · routing and / or copying packets to one or more prepared target cells, and / or

[0053] Prepare edge cloud capabilities, and / or

[0054] Check and / or prepare QoS for service operation.

[0055] Embodiments of cellular networks supporting conditional handover (e.g., for vehicular networks and / or for mobile gNBs) will bring (but not limited to) several new concepts, such as:

[0056] Not removing CHO configuration data after CHO execution,

[0057] Configuration data for CHO of multiple consecutive cells,

[0058] Providing CHO configuration data via broadcast / multicast signaling,

[0059] The initially active or inactive CHO configuration,

[0060] · Ask the target gNB or target cell for the sequential CHO configuration for the target cell,

[0061] Provide sequential CHO configuration for the target cell,

[0062] Inform the UE when sequential CHO is not possible,

[0063] Notify the previous cell or previous serving cell and the future cell or potential target cell of the CHO completion,

[0064] Provide the UE’s CHO configuration data as part of the UE context information, and

[0065] • In case CHO does not perform as expected, the UE reconnects to the network.

[0066] It should be noted that any embodiment defined by the claims may be supplemented by any of the details (features and functions) described in the preceding paragraphs.

[0067] Furthermore, the embodiments described in the above sections may be used alone or may be supplemented by any features in another section or by any features included in the claims.

[0068] In addition, it should be noted that the various aspects described herein can be used alone or in combination. Therefore, details can be added to each of the individual aspects without adding details to another aspect of the aspect.

[0069] It should also be noted that the present disclosure explicitly or implicitly describes features that can be used in user equipment and cellular networks. Therefore, any features described herein can be used in the context of user equipment and cellular networks.

[0070] Furthermore, any features and functions described herein may be implemented in hardware or software, or may be implemented using a combination of hardware and software.

[0071] Further embodiments of the inventive user equipment and / or the inventive cellular network are defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Hereinafter, various embodiments of the present disclosure are described in more detail with reference to the accompanying drawings, wherein:

[0073] Figure 1a ) shows a schematic communication diagram of a handover failure situation;

[0074] Figure 1b ) shows a schematic communication diagram of another switching failure situation;

[0075] Figure 2 It is a schematic communication diagram of the prior art condition switching;

[0076] Figure 3 A schematic diagram illustrating an embodiment of a cellular network with multiple sequential conditional handoffs;

[0077] Figure 4 A schematic diagram showing an embodiment of CHO configuration preparation in sequential conditional switching;

[0078] Figure 5 A schematic diagram showing an embodiment of CHO configuration preparation in sequential conditional switching;

[0079] Figure 6 A schematic diagram illustrating an embodiment of a scenario in which a given switch in a sequential conditional switch is not possible;

[0080] Figure 7 A schematic diagram of an embodiment of a scenario after a random access CHO from cell 1 to cell 2 is successful is shown;

[0081] Figure 8 A schematic diagram showing an embodiment of a scenario with incorrect predictions.

[0082] Fig. 9 A schematic representation of an embodiment showing communication between a UE and several cells of a cellular network;

[0083] Fig.10 A schematic representation of an embodiment of a general communication between a UE and a cellular network is shown.

[0084] Fig.11 Configuration data for a group of UEs whose mobility paths are known is shown. DETAILED DESCRIPTION

[0085] In the following, various embodiments and aspects of the invention will be described.

[0086] It should be noted that any embodiment defined by the claims may be supplemented by any of the details (features and functions) described herein.

[0087] Furthermore, the embodiments described herein may be used alone or may be supplemented by any feature in the description or by any feature contained in the claims.

[0088] In addition, it should be noted that the various aspects described herein can be used alone or in combination. Therefore, details can be added to each of the individual aspects without adding details to another aspect in the aspect.

[0089] It should also be noted that the present disclosure explicitly or implicitly describes features that can be used in user equipment and cellular networks. Therefore, any features described herein can be used in the context of user equipment and / or cellular networks and / or in the context of conditional handover (CHO) for vehicular networks and mobile next generation NodeBs (gNBs).

[0090] Furthermore, as will be described in the "Implementation Alternatives" section, any of the features and functions described herein may be implemented in hardware or software, or may be implemented using a combination of hardware and software.

[0091] As mentioned above, conditional switching is intended to avoid, for example, a radio link failure (RLF) as shown in FIG. 1 , which shows two exemplary failure scenarios, namely Figure 1a 100a and Figure 1b In the 100b, both situations can be avoided by conditional switching (CHO).

[0092] Figure 1a A schematic representation of a failure scenario 100a is shown, which includes a user equipment 110, a source node or base station 310, and communications and / or data exchanges between the UE 110 and the source node 310.

[0093] Failure scenario 100a includes a step in the communication between UE 110 and source node 310 , wherein UE 110 intends to send a measurement report 180 to source node 310 , but the measurement report does not reach base station 310 .

[0094] Since UE 110 does not receive a response from source node 310 and / or the condition deteriorates, UE 110 declares a radio link failure (RLF) and initiates a reestablishment process 190. Reestablishment process 190 includes: a reestablishment request 193 sent from UE 110 to source node 310; a reestablishment acknowledgement message 196 sent from source node 310 to UE 110; and a reestablishment completion message 199 sent from UE 110 to source node 310. As a final step, source node 310 provides UE 110 with reconfiguration data.

[0095] Another failure case 100b is caused by Figure 1b Indicates. Figure 1a similar, Figure 1b Including UE 110, source node 310 and communication between UE 110 and source node 310. Figure 1a In contrast, the measurement report sent by the UE 110 reaches the source node 310 and / or the network. The network decides to perform a handover and issues a handover command 185 from the source node 310 to the UE 110.

[0096] exist Figure 1b In this case, the handover command does not reach UE 110. Figure 1a Similarly, UE 110 does not receive a response and / or the condition of UE 110 deteriorates, and UE 110 declares RLF and initiates the following steps: Figure 1a The reconstruction process described in 190.

[0097] Figure 1a , Figure 1b A possible solution to the failure situation described in is to pass Figure 2 The conditional switching (CHO) shown in Figure 2 is used to improve mobility robustness. Figure 2 A schematic representation of communication and / or data exchange between a UE 110, a source node 310 and a potential target node 120 is shown.

[0098] The first step of a conditional handover (CHO) includes sending a CHO request 240 from the source node 310 to the potential target node 120. For example, the CHO decision is triggered earlier (e.g., triggered by a higher-level decision) or can be based on the source node 310 request, or the potential target node 120 can review the possibility of CHO, for example, it can perform admission control.

[0099] After successful admission control, the potential target node 120 sends a CHO request acknowledgement 250 (if required) and further RRC reconfiguration data to the source node 310 .

[0100] As a next step, the source node 310 provides 140 CHO configuration data to the UE 110. The CHO configuration data comprises triggering criteria or triggering conditions or conditions of the potential target node 120 and corresponding RRC reconfiguration data.

[0101] The UE 110 continuously monitors, or at least frequently checks 150, a CHO trigger condition or conditions of one or more target cells 120. If a trigger condition, or a subset of a set of trigger conditions, is met, the UE 110 performs 350 a handover (HO) that includes a random access and synchronization procedure 260 between the UE 110 and a given potential target node 120. When the RRC reconfiguration is complete, the UE 110 notifies the potential target node 120 via an RRC reconfiguration complete message 270.

[0102] As a final step, the target node 120 notifies the serving source node or source base station 310 and / or the core network indicating the successful execution of the CHO. With the source node 310 releasing the UE 110 context, the path switch is completed 280. In addition, the access and mobility management function (AMF) starts to learn the new location of the UE 110 and / or the user plane function starts to learn the new target cell 120 in order to forward packets to the new target cell 120.

[0103] In other words, the steps of the latest CHO can be described as follows:

[0104] 1. As a first step, the source gNB 310 makes a decision to configure CHO.

[0105] - The CHO decision may be based on, for example, UE 110 measurements, while the CHO configuration may be triggered earlier compared to a regular HO configuration.

[0106] The CHO decision may also be based on, for example, a high-level decision, for example based on:

[0107] The load of surrounding base stations, and / or

[0108] Type of service, and / or

[0109] Application requirements on the UE 110, base station 310 or network, and / or

[0110] Another UE sending a trigger via a sidelink (SL) interface, and / or

[0111] The source node is triggered by an entity in the network or the Internet, such as a V2X application server or a roadside unit (RSU).

[0112] - The CHO decision may be based on the source node 310 requesting a CHO, eg to the target cell 120, and providing the UE 110 configuration.

[0113] – Alternatively, the target node 120 performs, for example, admission control and, if successful, provides the cell configuration to the source node 310 , which the source node 310 may forward to the UE 110 in a CHO configuration message 140 .

[0114] 2. As a second step, the source gNB 310 provides CHO configuration, including:

[0115] – Provide the UE 110 with the CHO triggering criteria and configuration of the target cell.

[0116] 3. As a third step, UE 110 makes a CHO decision in the following cases

[0117] – Once the conditions are met, e.g. UE 110 can access the target cell, or

[0118] – satisfies a subset of a set of conditions, e.g. it could be a set of rules.

[0119] 4. As a fourth step, UE 110 sends a handover complete message

[0120] – By sending an RRC Reconfiguration Complete message to the new source cell

[0121] – and the CHO configuration is released.

[0122] 5. As a final step, the target cell 120 notifies the source gNB 310 and the core network or cellular network.

[0123] – Indicates successful CHO execution.

[0124] –The target node 120 notifies the source gNB 310, causing the source node 310 to release the UE 110 context.

[0125] – Target notification to the core network, in particular:

[0126] The AMF starts learning the new location of the UE 110, and / or

[0127] The UPF starts to learn about the new target cell 120 (performs path switching) to forward packets to the new target cell 120 .

[0128] like Figure 2 As shown, in the latest CHO, only one handover candidate is provided, or in other words, the next handover candidate. Multiple candidates may be provided, but always from the same current serving and / or source cell 310. This means, for example, that after performing a CHO and eventually completing the CHO, the UE has no CHO configuration until the next CHO configuration occurs. For example, in the case of a fairly fast cell change, the time may not be sufficient to, for example, exchange a large amount of signaling, and the overhead associated with such a process may be minimized.

[0129] Typically, the configuration of CHO is only valid for a certain period of time and only for a single handover from the current serving cell to one or more new cells or target cells, for example. This means that CHO is configured separately in, for example, each serving cell. For example, once a HO is performed or completed, the next CHO will need to be configured.

[0130] For example, for terrestrial CHO, it is important to remove or delete the CHO configuration at a certain point in time. This is typically done by explicit signaling from the cell or the gNB from the cell, for example after expiration of a validity timer or, for example, after a successful completed handover. In conventional procedures, the CHO configuration is removed or deleted after a successful completion of CHO (in Figure 2 in step 4 of the above).

[0131] For example, a train, plane or car may move at high speed on a determined route (e.g., on a train track, plane route, highway and / or street). For example, a network providing connectivity to corresponding devices may predict the user's movement path or route not only for the next cell, but also for the next few cells.

[0132] For example, in the new scenario described above, the network may have good knowledge of UE or gNB mobility or routes along a determined path across multiple cells.

[0133] For example, one concept on which embodiments of the present application are based is to configure multiple sequential CHO handovers and thus not remove or partially remove the CHO configuration after a successfully completed HO or CHO. The above-described conditional handover (CHO) is thus enhanced.

[0134] Embodiments disclose the following concepts: for example, multiple cells on a user equipment (UE) mobile path or route are configured as switching candidates, for example, to minimize air signaling and / or, for example, to ensure a reliable switching process or a multi-sequence conditional switching process at high speed. As an alternative to signaling individual switching candidates on a per-switch basis, signaling along a path or route of a cell / switch is provided. The path can be described by coordinates (e.g., GPS coordinates) and can be located on a 2D plane or on a 3D plane, the latter containing the altitude parameter of the UE. In addition, the path can also contain a motion vector, which contains information about the speed and / or acceleration and / or direction of the moving UE.

[0135] Figure 3 A schematic diagram of an embodiment including a mobile UE 110 and / or a mobile gNB 120 represented by a directional arrow 330 is shown. Figure 3Also included are seven target cells 120 of the cellular network, namely, Cell 1 - Cell 7 , which are aligned on the moving path or expected future route of the moving UE 110 .

[0136] Figure 3 The UE 110 is configured to receive configuration data 1110 from cell 1. The configuration data 1100 includes a plurality of sequential CHO trigger conditions and corresponding CHO configuration information or data for conditional handovers from cell 1 to cell 2, from cell 2 to cell 3, and from cell 3 to cell 4. The CHO configuration data 1110 includes not only the trigger conditions and configuration information or data for handovers from a current serving cell to a next potential target cell, but also the trigger conditions and configuration data for handovers in which the current serving cell is not involved.

[0137] When UE 110 is moving on a moving path or route from cell 1 to cell 4, UE 110 monitors or checks the conditions or trigger conditions of configuration data 1100 and checks whether the trigger conditions are met, or if the conditions are applicable, UE 110 performs CHO with the help of CHO configuration data, or at least UE 110 triggers CHO.

[0138] When the UE 110 arrives at cell 3, the configuration data 1100 of the UE 110 is updated 320 and the UE 110 receives CHO update data 325 from cell 3. The CHO update data or CHO configuration update data 325 includes further triggering conditions and configuration information or data for handovers from cell 3 to cell 4, from cell 4 to cell 5, and from cell 5 to cell 6. For example, the communication of the moving UE 110 is made more reliable by the UE 110 receiving the CHO configuration update 320 before reaching the last cell of the configuration data 1100 provided by the last update or by cell 1, for example.

[0139] When UE 110 is moving on a moving path or route from cell 3 to cell 6, UE 110 monitors the triggering condition of configuration data 1100. Whenever the triggering condition is met, UE 110 performs or completes CHO according to the CHO configuration data.

[0140] When UE 110 arrives at cell 5, CHO configuration update data 325 is updated 320 to UE 110 by cell 5, and CHO configuration update data 325 includes further triggering conditions and configuration data for handover from cell 5 to cell 6 and from cell 6 to cell 7. Configuration update data 325 may include a new version of configuration data 1100 or only a changed or incremental portion of configuration data 1100.

[0141] In an embodiment, multiple sequential CHO configurations, ie multiple configurations for sequential cell change, are provided, for example, by using a single CHO configuration or using a single CHO configuration data 1100. For example, an explicit indication in the signaling may indicate, for example, that sequential CHO configurations are provided.

[0142] The configuration may or may not be active in the initial state. This behavior may be hard-coded in the specification or may be configurable through signaling. In the latter case, there may be bits in the RRC message to inform the UE: for example, whether CHO has been activated after configuration and / or for example, whether CHO still needs to be activated after configuration.

[0143] In an alternative embodiment, for example, the CHO configuration or CHO configuration data is deleted only when the mobility pattern deviates from the expected mobility pattern or expected future route. For example, the CHO configuration is either removed after a certain timer expires (e.g., the handover is too late) or after some configured event, such as an unexpected handover to a different cell or a handover to a target cell not included in the CHO configuration data 1100. For example, if such an event occurs on the UE side, the UE can contact the network or cellular network to notify the network of this situation, or if the event occurs on the network side, the network can configure the UE with new handover settings or new CHO configuration data 1100.

[0144] In this case, for example, three sequential CHOs. In other words, the UE receives CHO configuration data having CHO conditions and CHO configuration information for three sequential CHOs. In an embodiment, for example, the UE performs or completes the first CHO from cell 1 to cell 2, and it keeps the subsequent CHOs, or keeps checking the applicability of the triggering conditions to cell 3 and cell 4. In this case, multiple CHOs can be performed with, for example, a single configuration or CHO configuration data, and, for example, the UE even configures the CHO or the CHO configuration data for the next CHO immediately after the CHO is performed or completed. Doing so can improve reliability and can reduce overall signaling overhead.

[0145] In another embodiment of the apparatus of the present invention, different thresholds and signal levels may be assigned to each configured CHO handover, for example as a CHO trigger condition, e.g., CHO of cell 1→cell 2 may occur with different thresholds and / or signal levels compared to CHO of cell 2→cell 3.

[0146] For example, by configuring the next CHO sequence, or by updating the CHO configuration data before reaching the last CHO, the entire mobile process can be made quite reliable. For example, a CHO update is received in cell 3, although CHO has been configured or the CHO configuration data includes trigger conditions and CHO configuration information up to cell 4. Even if the CHO configuration or the update of the CHO configuration data in cell 3 fails, the network can still provide the CHO configuration or the update of the CHO configuration data, for example, in cell 4, and thereby have, for example, a certain reliability margin.

[0147] This marking or feature also enables the UE and / or the network to react, for example, if a new CHO configuration or CHO configuration data (e.g., in cell 3) cannot be successfully configured or updated. For example, the UE can notify the application to react, for example, a message can be given to the upper layer, and / or a user in a car that is driving autonomously can be notified that he / she should take over the steering wheel.

[0148] For example, in the case of Cloud RAN, the cell or potential target cell for which sequential CHO is configured may belong to Cloud RAN where the control plane functions (RRC+RRM) are, for example, centralized. This may avoid, for example, sending a lot of inter-gNB signaling to a set of target gNBs before CHO can be configured.

[0149] For example, the CHO configuration parameters provided to the UE for each consecutive cell change may include:

[0150] Physical cell identity, and / or

[0151] Trigger threshold or trigger condition (e.g., a certain RSRP, RSRQ, SINR, RSSI), and / or

[0152] The reference signal to be measured (SSB, CSI-RS or both, DMRS), and / or

[0153] Beam information, and / or

[0154] Average calculation information, and / or

[0155] Target cell configuration, and / or

[0156] Resource pool configuration or usage / utilization for V2X.

[0157] After the CHO is successfully executed, the new cell or the new serving cell and / or the new target cell may, for example, add some criteria, for example, extend the path or route, modify or release the CHO configuration from the sequence list or from the CHO configuration data. For example, in order to save signaling, incremental partial signaling or change partial signaling may be provided, and only the changed configuration items are signaled.

[0158] Figure 4 A schematic diagram showing an embodiment of a CHO configuration preparation in a sequential conditional handover, which includes a Figure 3 The first four cells, namely, cell 1 to cell 4, of which cell 1 is the serving cell or source cell 310 or the serving source cell, and the other cells (cell 2 to cell 4) are potential target cells 120.

[0159] and Figure 2 The first two steps of the prior art CHO are similar, Figure 4 1 , the serving cell 310 in the mobile path or route of the UE 110 sends a CHO configuration request 240, but not only to the neighboring cell (cell 2), but also to a cell farther away (e.g., to cell 3 or to cell 4) in the mobile path or route of the UE 110. That is, the serving cell 310 sends the CHO configuration request 240 for a conditional handover, in which the serving cell 310 is not even involved, such as the CHO between cell 3 and cell 4.

[0160] The potential target cell 120 may review the possibility of a potential CHO, for example, perform admission control, and / or reserve resources and prepare for CHO. If CHO is possible, the potential target cell 120 (e.g., cell 2, cell 3, and / or cell 4) acknowledges the CHO configuration request 240 with a CHO configuration acknowledgement message 250. The CHO configuration acknowledgement message 250 may include other information, such as CHO configuration information or data.

[0161] After receiving the CHO configuration acknowledgement message 250 , multiple sequential CHO configuration data 1100 are sent 140 from the serving cell 310 to the UE 110 .

[0162] In other words, the source gNB or serving cell may request CHO to the target gNB or target cell, e.g. before CHO is configured to the UE or before the UE receives CHO configuration data, e.g. to allow the target gNB or target cell, e.g. to perform admission control, reserve resources and prepare for CHO. The target gNB may confirm the CHO request to the source or serving cell and may provide certain parameters back to the source or serving cell, i.e., e.g. to the UE during CHO configuration. These parameters may be provided to the UE within the CHO configuration.

[0163] For example, in the CHO configuration request 240, the source cell 310 or serving source cell 310 may also request CHO not only for itself as a serving cell (e.g., requesting CHO of cell 1→cell 2 from cell 1), but also for other cells that may become serving cells and may trigger CHO within their coverage (e.g., requesting CHO of cell 2→cell 3 from cell 2). To this end, a list of cell changes may be provided to the target cell 120, so that, for example, the target gNB or target cell can know which source gNB or cell the CHO is expected to come from.

[0164] For example, in the configuration request message 240 , the serving source cell 310 may provide a complete list of sequential CHOs and / or may only provide relevant CHO information to each target cell 120 .

[0165] For example, because the mobility path or route is known, the expected timing for the predicted execution or completion of the UE arrival and / or CHO may also be provided to the target cell 120. This information may support the target gNB, for example, in accurate admission control, reserving resources and preparing for CHO, and may limit resource reservations to the time when the UE is actually expected, rather than, for example, permanent resource reservations. The corresponding cell may track, for example, the load of all UEs within the cell and / or UEs expected to arrive at its cell.

[0166] For example, inter-gNB signaling is exchanged in LTE connected to the Evolved Packet Core via X2 and / or S1-MME interfaces and in LTE / NR connected to the 5G Core via Xn and NG-C interfaces.

[0167] and Figure 4 similar, Figure 5 A schematic diagram showing an embodiment of a CHO configuration preparation in a sequential conditional handover, which includes a Figure 3 The first four cells, namely, cell 1 to cell 4, of which cell 1 is the serving or source cell 310 and the other cells (cell 2 to cell 4) are potential target cells 120.

[0168] Similar to Figure 4 , a CHO configuration request 240 is sent from the serving cell 310 to the potential target cells 120, such as cell 2-cell 4. The potential target cells review the possibility of CHO and / or prepare for CHO. If CHO is possible, the serving cell 310 receives a CHO configuration acknowledgement message 250 from the potential target cell 120.

[0169] As a next step, sequential CHO configuration data is sent by the serving cell 310 to the UE 110. In parallel with sending the sequential CHO configuration data to the UE 110, the serving cell 310 confirms the decision requested in the CHO configuration request by sending a CHO confirmation message 510. The CHO confirmation message may contain other information about CHO, such as a cell identity, time information about the time when the UE 110 is expected to be in a certain cell, and / or which service the UE 110 is using for each slice.

[0170] exist Figure 5 In the illustrated embodiment, the serving cell 310 confirms the requested CHO configuration to potential target cells 120 such as cell 2-cell 4 and may provide additional information regarding, for example, cell identity, time information when the UE is expected to arrive, and / or the service / slice that the UE 110 is using.

[0171] In other words, once the CHO configuration is determined (e.g., based on feedback from all target candidates or target cells 120), the serving cell 310 may provide, for example, the CHO configuration or CHO configuration data to the UE. At the same time, information about, for example, the CHO switching sequence may also be provided to all target gNBs or target cells.

[0172] For example, the CHO configuration confirmation message 510 confirms the decision requested in the CHO configuration request 240 and / or may provide a final result for the sequential CHO configuration sent to the UE, e.g.

[0173] A cell identity, which is a physical cell identity and / or a global cell identity, and / or

[0174] The time and / or time window during which the UE is expected to be in a cell or target cell, and / or

[0175] The services / slices used and / or expected by the UE in the new cell.

[0176] The target base station or target cell 120 may be unavailable and / or after reviewing the possibility of CHO, the potential target cell 120 may decide that it will not be available for CHO. Figure 6 This scenario is illustrated.

[0177] Figure 6 A schematic diagram showing an embodiment of a scenario in which a given switch in a sequential conditional switch is not possible. Figure 4 similar, Figure 6 shows a moving path along the moving UE 110 Figure 3The first four cells, namely, cell 1 to cell 4, of which cell 1 is the serving or source cell 310, and the other cells (cell 2 to cell 4) are potential target cells 120. Figure 4 In contrast, among the possible three target cells (cell 2 - cell 4 ), cell 3 cannot reserve resources and / or it is temporarily unavailable and / or it may not be able to support UE 110 .

[0178] like Figure 4 As discussed in the above, a CHO configuration request 240 is sent from the serving cell 310 to potential target cells 120, such as cells 2-4. The potential target cells review the possibility of CHO and / or prepare for CHO. In the case where CHO is possible, the serving cell 310 receives a CHO configuration acknowledgement message 250 from the potential target cells 120 (e.g., from cells 2 and 4).

[0179] Unlike the above scenario, the serving cell does not receive the CHO configuration positive acknowledgement message 250 from cell 3. For example, in the case where cell 3 is temporarily unavailable, cell 3 does not send any message to the serving source cell 310. It is also possible that the target cell 120 (such as cell 3) cannot reserve resources or cannot support the UE, or for other reasons, it cannot positively acknowledge the CHO configuration request 240. In this case, the target cell 120 (such as cell 3) sends a CHO configuration negative acknowledgement (NACK) message 610 to the serving source cell 310.

[0180] After receiving the CHO configuration negative acknowledgement message 610, the serving cell 310 may seek alternatives in the given cellular network, such as a different possible base station 120 or a different frequency layer.

[0181] If it is recognized and / or determined that sequential CHO is not possible, the serving source cell 310 notifies 620 the UE 110 that reliable handover may not be guaranteed. The message may include other information, such as the last cell in which sequential CHO is possible, time information (e.g., time until reliable handover can be guaranteed), and / or service restriction and / or quality of service (QoS) restriction parameters. The serving cell 310 may also notify the core network and / or the AMF in the core network or in the cellular network to resolve situations such as base station overload by, for example, releasing certain users of a given base station.

[0182] In other words, for example, sequential CHO may not always be possible. The target gNB or target cell 120 may decide, for example, that it cannot reserve resources (e.g., overload situation and / or the cell is temporarily unavailable for some reason), or may not be able to support certain UEs, e.g., may not provide slices for this service. In this case, the target gNB may not respond with a CHOConfig ACK message, but instead may respond with, for example, a CHO Config NACK message. For example, the target gNB or target cell may not inform the source gNB or source cell of the reason why it does not support sequential CHO configuration or the requested CHO configuration.

[0183] For example, the source gNB or serving source cell or serving cell may seek alternatives based on the feedback, such as using different cells or target cells on different frequency layers, and / or may ultimately decide that sequential CHO is not possible. It may inform the UE that a reliable handover may not be guaranteed. This signaling to the UE may contain information such as:

[0184] The time at which reliable switching or communication can usually be provided, or the time at which reliability cannot be guaranteed, and / or

[0185] The last cell configured with sequential CHO, and / or

[0186] which services are still supported by, for example, autonomous driving, and which services are no longer supported by autonomous driving, and / or

[0187] Which QoS parameters may still be supported and which may no longer be supported, such as reliability, BLER rate, certain outage time, delay.

[0188] For example, the source gNB or serving cell may also notify the AMF in the 5G core network (5GC) or in the cellular network of this event, and / or may provide similar information to the 5GC. The 5GC may forward such information to, for example, an application server, and / or may trigger the release of certain users or services, and / or may renegotiate QoS settings with the radio network and / or the corresponding application server, for example.

[0189] Figure 7 FIG. 1 is a schematic diagram of an embodiment of a scenario after a random access CHO from cell 1 to cell 2 is successful. Figure 4 similar, Figure 7 shows a moving path along the moving UE 110 Figure 3 The first four cells of the target cell are cell 1 to cell 4. The scenario includes cell 1 as the previous serving cell 710, cell 2 as the new serving source cell 720, and other potential target cells 120 (cell 3 to cell 4).

[0190] The first step of this scenario includes UE 110 completing 350 a random access CHO from cell 1 to cell 2. Cell 1 becomes the previous serving cell 710, while cell 2 becomes the new serving cell 720.

[0191] As a next step, the new serving cell 720 notifies 730 the previous serving source cell 710 of the successful CHO, which causes the previous serving cell 710 to release the UE 110 context.

[0192] New serving source cell 720 also informs potential target cell 120 of the successful CHO via CHO status update 740. Status update 740 may contain other information important for resource reservation of potential target cell 120 and / or for expected arrival time of UE 110, which may enable better prediction for UE 110.

[0193] In other words, after the UE and the target gNB successfully complete the CHO execution (such as Figure 2 4), the target gNB or target cell 720 may notify the source gNB 710 of the successful CHO execution for UE context release (e.g. Figure 2 It may also notify the core network, for example, to perform a path switch. According to an embodiment, a new CHO state update message may also be sent, for example, to the future cell 120, to the CHO candidate or the target cell 120.

[0194] For example, through this message, future cells or potential target cells may update their resource reservations and / or the expected arrival time of the UE.

[0195] For example, the signaling to the future gNB or target cell may contain information such as:

[0196] The time when the UE arrives at the new serving cell, and / or

[0197] The time at which the UE can be expected to arrive in the future cell, and / or

[0198] The services and / or slices that the UE is currently using or expects in future cells, and / or

[0199] The speed at which the UE is moving, and / or

[0200] Motion vectors of moving UEs, and / or

[0201] The precise GPS coordinates of the UE in 2D or 3D format, and / or

[0202] UE's motion vector, and / or

[0203] · Past neighborhood change history, and / or

[0204] · statistical data about business activities, and / or

[0205] • Updated UE identity (eg C-RNTI), and / or mapping with the UE identity in the previous cell.

[0206] In the case where the UE context is exchanged, for example between network nodes or cells (e.g. between gNBs and / or between a gNB and an AMF), the CHO configuration of the UE may be included in the UE context signaling.

[0207] Various embodiments rely on predicting the UE's moving path or expected future route. Predicting the moving path is highly probable, but sometimes it is still just a prediction, such as Figure 8 shown. Figure 8 A schematic representation of an embodiment of an incorrect prediction scenario is shown, wherein the prediction fails for some reason and the CHO switch is not performed as predicted or as expected.

[0208] Figure 8 The scenario includes a predicted moving path or an expected future route of the moving UE 110. Figure 3 According to the prediction, UE 110 moves on the predicted moving path and performs CHO with each cell (cell 1-cell 4) along the predicted moving path or the expected future route. Figure 8 In the example, the potential target cell (cell 2) cannot reserve resources and / or it is temporarily unavailable and / or may not be able to support CHO with UE 110. Cell 2 becomes a failed predicted serving cell 725.

[0209] Due to the predicted or expected CHO failure with cell 2, the UE searches for a new cell and connects 810 to the new cell, i.e., cell 8. That is, cell 1 becomes the previous serving cell 710, and cell 8 becomes the new serving cell 720. Cell 2 may be the preferred target cell, and cell 8 may be the backup target cell.

[0210] After successfully switching from previous serving cell 710 to new serving cell 720, if UE 110 is still connected to previous cell 710, UE 110 sends a message with CHO failure indication 820 to new serving cell 720 and / or previous cell 710. The message with CHO failure indication 820 may contain other information, such as information in the form of a measurement report.

[0211] The new serving cell 720 may query 830 the UE 110 for other UE and / or CHO context information. Based on the received context information, the new serving cell 720 may contact the previous cell 710 and / or forward information to the previous cell 710.

[0212] Since the previous prediction or anticipation failed, the CHO configuration data 1100 of the UE 110 needs to be updated 320 by the new serving cell 720. The new serving cell 720 also notifies the potential target cell 320, for example, in the form of a status update 740. Notifying the potential target cell 120 may allow the potential target cell 120 (cell 3-cell 4) to release the resources reserved for the UE 110.

[0213] In other words, the present invention relies on a determined UE mobility, such as predicted, or on an expected future route. In case, for example, such a CHO handover is not performed as expected, such as a certain CHO within a certain time window, it may be necessary to define the UE behavior to maintain the radio link and / or update the CHO configuration or CHO configuration data.

[0214] For example, the UE may be configured to perform CHO to a specific target gNB or target cell at a specific or expected location and / or within a specified or expected time window. For example, in the case where the UE passes the corresponding location and / or corresponding time window and does not see the expected target cell or a different cell (e.g., cell 8), it may, for example, tell the source gNB whether it is still connected using a report or measurement report and / or a CHO failure message, and / or may tell a new target gNB or new serving cell that it has connected to, for example after a RACH / connection setup procedure, that the CHO configuration was incorrectly predicted or expected, and / or that the CHO configuration or CHO configuration data may need to be updated.

[0215] For example, a message or report from the UE to the gNB or serving cell may include,

[0216] CHO failure indication, and / or

[0217] UE positioning information (2D or 3D), and / or

[0218] Timestamp information, and / or

[0219] Some signal strength measurements associated with the UE location and time, and / or

[0220] Its CHO configuration, and / or the cell in which the context of the CHO configuration is stored, and / or

[0221] Information about the last cell to which the UE was connected (e.g., physical cell identity or global cell identity) and its UE identity in that last cell (e.g., C-RNTI), and / or

[0222] • Information about cells where CHO is expected.

[0223] For example, based on the UE failure indication, the newly connected gNB or new serving cell may forward some information to the last connected cell or previous serving cell. For example, it may also query the UE and / or CHO context information. Once it receives the UE and / or CHO context, the new cell or new serving cell may update the CHO configuration or CHO configuration data to the UE.

[0224] For example, the new cell may also notify the previously expected cell or potential target cell respectively that the CHO configuration and / or reservation for this UE will be deleted, and / or the CHO status will be updated.

[0225] Alternatively, the UE may, for example, send only a failure indication or report to the gNB or new serving cell and provide a more detailed report to the gNB if requested. Once the gNB or new serving cell requests a full report and / or measurement data, the UE may send it to the gNB or the new serving cell.

[0226] As an alternative to the UE providing a failure message, the source gNB or previous serving cell may also see that the UE did not perform CHO as expected and may, for example, ask the UE to provide some measurements or measurement data.

[0227] Fig. 9 A schematic diagram of an embodiment of communication between a UE 110 and several cells (Cell 1 -Cell 5) of a cellular network is shown.

[0228] As Fig. 9 In the first step, UE 110 sends a configuration request 380 to the serving cell, in particular to cell 1. UE 110 receives 140 configuration data 1100 from cell 1. The received configuration data 1100 is sequential configuration data, which includes multiple trigger conditions and CHO configuration data, in particular for conditional handover from cell 1 to cell 2, from cell 2 to cell 3, from cell 3 to cell 4, and from cell 4 to cell 5.

[0229] Alternatively, before sending 140 the configuration data 1100 to the UE 110, the cell 1 sends a CHO configuration request to the potential target cells (cell 2-cell 5) and receives a CHO configuration acknowledgement message 250 from the cells 2-cell 5. After receiving the CHO acknowledgement message 250, the configuration data 1100 is sent 140 to the UE 110.

[0230] When the triggering condition is met, UE 110 sends 160 a CHO request to cell 2. Cell 2 acknowledges the request with a CHO confirm message 170 sent to UE 110. UE 110 completes or triggers the conditional handover and notifies cell 2 that the conditional handover is completed.

[0231] After completing the conditional handover, the UE 110 modifies the sequential CHO configuration data, for example by deleting 210 the completed conditional handover from cell 1 to cell 2 and retaining or keeping the second part of the conditional data.

[0232] At the same time, cell 2 sends 730 a status update to the previous serving cell (cell 1) and issues 740 a CHO status update to potential target cells (cells 3-5).

[0233] It is also possible that one of the potential target cells 120 (eg Fig. 9 Cell 4 in the conditional handover cannot be used as a conditional handover partner. Cell 4 negatively acknowledges the conditional handover by sending a CHO negative acknowledgement (NACK) message to the current serving cell (cell 2). The current serving cell (cell 2) forwards the CHO negative acknowledgement message to UE 110.

[0234] In addition, cell 2 is searching for an alternative cell, i.e., an alternative to cell 4. Since cell 5 appears to be a good alternative, cell 2 sends a CHO request to cell 5. The alternative serving cell (cell 5) acknowledges the CHO request by sending a CHO acknowledgement (ACK) message to the current serving cell (cell 2). The current serving cell (cell 2) sends a configuration update 320 to UE 110 to modify the configuration data 1100 of UE 110. The new configuration data 1100 includes triggering conditions and configuration data for handover from cell 2 to cell 3 and from cell 3 to cell 5.

[0235] To give a better overview of some of the scenarios explained above, Fig. 9 Including, for example: UE 110 requests and receives multiple sequential configuration data; the completed CHO process includes the serving cell sending a CHO request to the potential target cell, receiving a CHO positive response and / or configuration data from the potential target cell, forwarding the CHO configuration data to the UE, performing or triggering CHO, and the new serving cell notifying the former serving cell and the potential target cell of the completed CHO. Other examples may include: the potential target cell negatively responds to the CHO, the new serving cell notifies the UE of a NACK message, searches and finds an alternative target cell, and notifies the UE with configuration update data.

[0236] Fig.10A schematic diagram of an embodiment including general communications between UE 110 and cellular network 130 is shown.

[0237] UE 110 receives configuration data or a configuration update from cellular network 140. The configuration data includes a plurality of trigger conditions and handover configuration data. When one or more trigger conditions are met, UE 110 is performing an i-th CHO with an i-th target cell. After completing the CHO, UE 110 may modify 210 its configuration data, which may include deleting data related to the i-th CHO that has been performed. Cellular network 130 may act synchronously, i.e., modify 220 its configuration data, which may include deleting data related to the i-th CHO that has been performed.

[0238] When the triggering condition is met, UE 110 is triggered to perform the next (jth) CHO with target cell number j. After performing the CHO, modifications to the configuration data may occur on the UE and / or on the cellular network side.

[0239] When further trigger conditions are met, the execution of the CHO is triggered, followed by optional modification of the configuration data.

[0240] At some point in this cycle, new configuration data is required by the UE 110. The UE 110 requests and / or receives a configuration data update 320, thereby allowing further conditional handover to be performed, provided that the triggering condition is met or where the triggering condition is applicable.

[0241] In some cases, the signaling overhead can be further reduced when more than one UE moves on the same mobile path or the same expected future route. For the described scenario, the mobile path of the gNB and / or a group of UEs may be well known. As an alternative to individual configuration for all UEs, for example, the CHO configuration or CHO configuration data or a portion thereof (such as the first part of the CHO configuration data) may be provided by RRC broadcast signaling (via a system information block (SIB)) or multicast signaling. The SIB may be dedicated to mobility or not. For example, each active UE must read the SIB and therefore also read and be aware of the CHO configuration or the broadcasted first part of the CHO configuration data.

[0242] Fig.11 Configuration data 1100 for a group of UEs with known moving paths is shown. The configuration data 1100 comprises a first part 1130 with a set of common parameters 1130 and a second part 1150 with a set of individual parameters.

[0243] The common parameters 1130 of the configuration data 1100 include group-specific common parameters and are configured to be transmitted via broadcast, groupcast, or multicast transmission.

[0244] Individual parameters 1150 of configuration data 1100 include user-specific parameters, such as identification information, and are configured to be transmitted via unicast transmission.

[0245] Some configuration data may be more static, such as based on cell deployment and / or street layout or LEO satellite routes, while other configuration parameters may be more dynamic, such as based on the target gNB or target cell’s response to the CHO request (e.g. Figure 2 In one embodiment of the apparatus of the present invention, the common and / or static parameters are signaled, for example, via RRC broadcast signaling, while the dynamic and / or individual parameters (such as the second part of the CHO configuration data) are signaled, for example, via UE-specific RRC signaling.

[0246] For example, in the case of a mobile LEO satellite, the HO of all UEs is expected to be performed at a predefined time. In addition, the next LEO satellite may be known and fixed. Therefore, all information for handover may be jointly provided to, for example, all UEs, instead of being signaled specifically.

[0247] For example, the broadcast information may broadcast a configuration of multiple movement paths or routes, such as directions by street. The path it is traveling may be detected by the UE, and / or the network may signal to the UE which path the UE may apply in its configuration.

[0248] The configuration may or may not be active in the initial state. For example, the first part and / or the second part of the configuration data may include separate activation information. This behavior may be hard-coded in the specification or may be configurable through signaling. In the latter case, there may be bits in the RRC message to inform the UE: for example, whether CHO has been activated after configuration, and / or for example, whether CHO still needs to be activated after configuration.

[0249] With this technique, CHO within a cell can be limited to some UEs and / or a group of UEs, for example riding a train or driving on a street. If it is inactive, the network can activate an already configured CHO execution trigger, for example via a Radio Resource Control (RRC) reconfiguration message after connecting to that gNB or cell, or for example via a Medium Access Control (MAC) control element that can be included in the header of a packet.

[0250] Other embodiments

[0251] Embodiments of the user equipment 110 support conditional handover to one or more cells 120 of the cellular network 130 .

[0252] The user equipment 110 is configured to receive configuration data 1100 from the cellular network 120. The configuration data 1100 indicates conditions for triggering a conditional handover to any of the target cells 120 of the cellular network 130.

[0253] The user equipment 110 is further configured to check 150 the conditions for suitability and, if applicable, trigger 160 a conditional handover. In other words, the configuration data 1100 relates to a plurality of target cells 120 of the cellular network 130, which are arranged, for example (but necessarily) along an estimated future route of the UE 110, and for each of the plurality of target cells 120, the configuration data 1100 may indicate one or more associated conditions, the suitability of which should be continuously determined by the UE 110, and if any one of them (or a combination of them, such as all of them) is met, then this situation should trigger the UE 110 to start a CHO to the respective target cell. Thus, the configuration data 1100 may be structured into parts, each part relating to a certain target cell and comprising one or more conditions associated with the respective target cell.

[0254] In a preferred embodiment, the user equipment is configured to: after completing 230, 350 conditional handover (or in other words, in response to having completed handover to a certain target cell), delete 210 the first part of the configuration data 1100 and retain the second part of the configuration data 1100, for example, delete the first part related to the conditional handover that has been completed 230, 350 (or respectively related to the corresponding target cell). As a result, the network does not need to update the configuration data of the UE after any CHO has been performed, and the UE is then exempted from checking the conditions related to the target cell that has completed CHO. In addition, it may not be desirable for the UE to switch back to the target cell in which CHO has occurred once among the multiple target cells through CHO.

[0255] The cellular network 130 may act 220 synchronously, i.e. it may modify the configuration data 220 synchronously, such that the configuration data remain equal on both sides (at the UE and at the network side). More precisely, the network may retain only those target cells prepared for CHO, for example by assigning corresponding CHO details to the UE 110, wherein the updated / synchronized configuration data still relates to these target cells.

[0256] In a preferred embodiment, a first portion of the configuration data 1100 relates to completed and / or concluded handovers, while a second portion of the configuration data relates to incomplete or incomplete handovers.

[0257] According to an embodiment, the user equipment 110 is therefore configured to continue checking 150 after the first triggering of the conditional handover. In other words, the configuration data 1100 relates to a plurality of target cells 120 of the cellular network 130, which are considered to form useful target cells to perform CHO even sequentially, one after another, rather than purely alternately with each other, whereby the UE continues to check the conditions of the configuration data after the first CHO triggered based on these conditions.

[0258] In a preferred embodiment, the user equipment is configured to trigger 160 the conditional handover by sending a signal 160 to the target cell and to complete 230, 350 the conditional handover by receiving a signal from the target cell.

[0259] According to an embodiment, the first trigger 160 involves a conditional handover from the first cell 120 to the second cell 120, and the continued checking includes checking 150 conditions for a conditional handover from the second cell 120 to the first cell 120 (i.e. back to the first cell, which is then also one of the target cells to which the configuration data relates) and / or any other cell outside the target cell. It should be noted that, for example, the conditions from the first cell 120 to the second cell 120 may be different from the conditions from the second cell 120 to the first cell 120. In this way, a handover may be made possible, for example, for the case where the UE makes a U-turn and traverses the estimated future route in reverse.

[0260] In addition to checking trigger conditions related to conditional switching, for example, the UE may also check unconfigured target cells, i.e., the usefulness of switching to any target cell that does not belong to the multiple target cells involved in the configuration data 1100 may be checked, and in the case where the unconfigured target cell is a suitable candidate (e.g., detected by triggering a measurement report or a different kind of configured / preconfigured trigger), the source cell is notified of the suitable switching candidate (e.g., using a measurement report or a report requiring reconfiguration of the conditional switching configuration). In this way, a switch to a suitable cell may be initiated. In the case of a conditional switch requiring addition to the target cell involved in the configuration data, the network or the current serving cell may send new configuration data or an update to the existing configuration to the UE. It is also possible to initiate a normal switch, in which the serving cell prepares for a switch to a target cell that has not yet been foreseen.

[0261] According to an embodiment, the user equipment 110 is configured to trigger 160 a conditional handover available to the user equipment 110 only within a limited time interval indicated in the configuration data. In other words, the conditional handover to a certain target cell may be regulated by the configuration data at least in part according to a time interval, during which the conditional handover is only allowed. Therefore, the UE 110 will have to check whether the current time falls within the time interval, and thus check whether the CHO to the corresponding target cell is available. For more than one target cell or all target cells involved in the configuration data, such a time interval may be given in the configuration data.

[0262] Depending on the embodiment, the limited time interval may be periodic, or limited to a single time or one time.

[0263] According to an embodiment, the configuration data 1100 comprises a start time and an expiration time of the finite time interval. The finite time interval may be defined by an interval and / or by a start time and an expiration time.

[0264] According to an embodiment, the configuration data 1100 comprises one or more finite time intervals and / or periodic time intervals assigned to different target cells 120. For example, when satellite target cells are used, periodic time intervals (e.g., a cyclic sequence of time intervals) may be defined, wherein the periodicity of the time intervals is related to the orbital periodicity of the satellite target cells.

[0265] According to an embodiment, the conditions for triggering (or triggering conditions) may include service-dependent triggers, such as URLLC deletion, ignoring common configurations or cells that do not support URLLC services, or lowering the priority of common configurations or cells that do not support URLLC services.

[0266] The trigger may also be a policy-dependent trigger, such as based on a charging model, where a specific UE may not be allowed to access a certain technology, such as a cheaper modem cannot access a multi-RAT eNB / gNB. That is, for example, based on the policy, a UE of a higher paying customer may have access to a certain technology.

[0267] The trigger may also be a handover failure trigger, where the UE may track the history of past unsuccessful handovers and may reduce the priority of handovers to target cells that have failed in the past and / or are overloaded and / or have rejected handovers in the past. This may also be a trigger signaled by the cellular network 120, such as a base station and / or cell sending a trigger and attaching a success probability based on past analysis. This may also be included in configuration data signaled by the cellular network, such as a base station and / or cell sending configuration data, where the success probability based on past analysis is attached to the trigger condition.

[0268] In a preferred embodiment, the configuration data 1100 includes preferred target cell configuration data and / or backup target cell configuration data, or indicates a preference regarding a conditional handover to a target cell.

[0269] In a preferred embodiment, configuration data 1100 includes target cell configuration data ranked and / or ordered by preference.

[0270] In a preferred embodiment, the configuration data regarding the preferred target cell and / or regarding the target cell 120 with the first (primary) preference comprises different trigger conditions than the configuration data regarding the backup target cell and / or regarding the target cell with the second (secondary) preference.

[0271] In addition, the triggering conditions of the backup target cell configuration data and / or the configuration data of the target cell 120 with the second preference include an initial triggering condition, according to which the handover to the preferred target cell and / or the target cell with the first preference has failed, that is, one or more conditions for CHO to the preferred target cell have been applied, but the handover ultimately failed.

[0272] For example, this grouping or ranking can be done so that

[0273] ·Prefer cells that ensure service continuity, and / or

[0274] Prioritize cells with more bandwidth, and / or

[0275] Prefer 5G / LTE over 3G, GSM or another RAT, and / or

[0276] ·Prefer cells with less occupancy or less communication resource pressure, and / or

[0277] Prefer small cells or cells operating at mmWave to macro cells with wider coverage that may operate at lower frequencies, and / or

[0278] • Prefer unlicensed cells to licensed cells.

[0279] These preferences may also be reversed, depending on, for example, policy, charging model, modem type, or the service being run.

[0280] In a preferred embodiment, the configuration data 1100 includes information about the order of target cells 120 on which the user equipment 110 intends to perform 230, 350 conditional handover. For example, the UE may check whether CHO to a certain target cell will result in the condition that the target cell becomes the nth target cell among the multiple target cells involved in the configuration data (where CHO is initiated for the target cell). If not, the target cell is not available for CHO.

[0281] In a preferred embodiment, the user equipment 110 is configured to update 320 the configuration data according to the configuration update 325 received from the cellular network 120. That is, the new configuration data is not sent to the UE in a standalone manner (i.e. completely new) but as a difference to the current version of the configuration data at the UE. In a preferred embodiment, or in other words, the configuration update or update message 325 may include a new version of the configuration data 1100 and / or only the changed parts of the configuration data 1100.

[0282] In a preferred embodiment, the configuration update or update message 325 changes the plurality of target cells 120 from a first set of cells to a second set of cells in such a way that the intersection of the first set and the second set includes the plurality of target cells.

[0283] In a preferred embodiment, the user equipment is configured to receive the first part 1130 of the configuration data 1100 via a broadcast or groupcast or multicast transmission and to receive the second part 1150 of the configuration data via a unicast transmission.

[0284] In a preferred embodiment, the first portion 1130 of the configuration data comprises group-specific parameters or common parameters and the second portion 1150 of the configuration data comprises user-specific parameters or individual parameters.

[0285] In a preferred embodiment, a first part of the configuration data can be overwritten by a second part of the configuration data, which means that common parameters can be overwritten by individual parameters.

[0286] In a preferred embodiment, the second part 1150 of the configuration data 1100 relates to the handover details of the UE. It may include identification information related to the identity of the user equipment and / or the RACH preamble code identity and / or the physical resource reservation in the target cell. For example, the identification information may include a user ID, RNTI, RACH preamble code, etc.

[0287] According to an embodiment, the user equipment is configured to check whether the second part 1150 of the configuration data 1100 includes identification information related to the identification of the user equipment and / or the RACH preamble identification and / or the physical resource reservation in the target cell, and if not, the current identification information of the user equipment is used for the identification and / or the default RACH resource pool and / or the random or default RACH preamble identification and / or the default physical resource reservation. For example, the identification information may include a user ID, an RNTI, a RACH preamble, etc.

[0288] According to an embodiment, the second part 1150 of the configuration data comprises separate activation information indicating to the user equipment 110 that the configuration data 1100 is active for the user equipment 110. The activation information and / or activation signal indicates activation and / or deactivation of the configuration, e.g. via a physical downlink control channel (PDCCH).

[0289] According to an embodiment, the first part 1130 and / or the second part 1150 of the configuration data 1100 comprises target cell configuration information indicating to the user equipment 110 a subsequent target cell configuration to be applied after handover to the target cell 120 .

[0290] According to an embodiment, the user equipment 110 is configured to check whether the first part 1130 and / or the second part 1150 of the configuration data 1100 includes target cell configuration information indicating to the user equipment 110 the subsequent target cell configuration to be applied after switching to the target cell, and if not, take over the source cell configuration or configuration information of the serving source cell 310 when the handover is triggered.

[0291] According to an embodiment, the first portion 1130 of the configuration data 1100 may include:

[0292] Physical cell identities associated with candidate target cells, and / or

[0293] Target cell configuration parameters, such as frequency or carrier bandwidth, and / or

[0294] RACH preamble, and / or

[0295] RACH opportunity for initial connection, and / or

[0296] A fallback process if the initial connection fails, and / or

[0297] · triggering thresholds, quantities and events indicating conditions for conditional switching to be performed, and / or

[0298] Reference signal to measure specifies the signal to be measured, and / or

[0299] Beam information, and / or

[0300] Average calculation information, and / or

[0301] The physical location of the target cell.

[0302] The user equipment 110 may derive, for example, its timing advance and / or power control value based on the distance to the target cell 120 .

[0303] According to an embodiment, the user equipment 110 is configured to check whether the first part 1130 of the configuration data 1100 comprises:

[0304] Physical cell identities associated with candidate target cells, and / or

[0305] Target cell configuration parameters, such as frequency or carrier bandwidth, and / or

[0306] RACH preamble, and / or

[0307] RACH opportunity for initial connection, and / or

[0308] A fallback process if the initial connection fails, and / or

[0309] · triggering thresholds, quantities and events indicating conditions for conditional switching to be performed, and / or

[0310] Reference signal to measure specifies the signal to be measured, and / or

[0311] Beam information, and / or

[0312] Average calculation information, and / or

[0313] The physical location of the target cell.

[0314] If not, the corresponding information of the current and / or default first part 1130 of the configuration data is taken over in the event of a triggering switch. That is, if the first part 1130 of the newly updated configuration data 1100 does not include any information about the above list elements, the UE will use the previously updated information or default information available instead.

[0315] According to an embodiment, the user equipment 110 is configured to receive configuration data 1100, wherein the configuration data comprises:

[0316] Physical cell identity, and / or

[0317] RACH preamble, and / or

[0318] RACH opportunity for initial connection, and / or

[0319] A fallback process if the initial connection fails, and / or

[0320] User ID (e.g., RNTI), and / or

[0321] Trigger thresholds, and / or

[0322] The reference signal to be measured, and / or

[0323] Beam information, and / or

[0324] Average calculation information, and / or

[0325] Target cell configuration, and / or

[0326] · Resource pool configuration or usage / utilization for V2X, and / or

[0327] The physical location of the target cell.

[0328] According to an embodiment, the user equipment 110 is configured to receive configuration data 1100, which may or may not include information about:

[0329] The expected time of the conditional switching interrupt, and / or

[0330] · Predetermined target cell, and / or

[0331] a statement that a certain service and / or QoS flow and / or logical channel and / or radio bearer is not supported in the target cell, and / or

[0332] Network slicing is not supported.

[0333] The continuity of the above information indicating the preparation of conditional switching to the network based on the predetermined target cell 120 is unreliable, wherein the predetermined target cell 120 is adjacent to one or more first target cells 120 adjacent to each other and one or more second target cells 120 adjacent to each other but not to the first target cell.

[0334] According to an embodiment, the user equipment is configured to trigger an update 380 of the configuration data from the serving cell 310 by sending a report (eg a measurement report) to the actual serving cell 310 and / or to the new serving cell.

[0335] If the user equipment is still connected to the serving cell 310 , sending a report to the serving cell 310 may inform the serving cell when the user equipment 110 is unable to perform a handover to one or more target cells 120 .

[0336] After the user equipment loses and reconnects to the cellular network, sending a report to the new serving cell 310 may inform the new serving cell 310 of the erroneous handover configuration.

[0337] According to an embodiment, the report includes

[0338] Handover failure indication, and / or

[0339] Location information of the user's device, and / or

[0340] Route information, and / or

[0341] Timestamp information, and / or

[0342] Signal strength measurement data associated with a physical cell identity, and / or

[0343] a handover configuration and / or a handover context configuration and / or information about a target cell in which the handover context configuration is stored, and / or

[0344] information about the last cell to which the user equipment was connected and the identity of the user equipment in that last cell, and / or

[0345] • Information about the target cell to which the user equipment is expected to perform a handover.

[0346] The route information may be, for example, a future route and / or a portion of a future route, or a list of possible routes for the user device 110. The route information may be, for example, waypoints as a list of GPS coordinates or motion vectors, which may contain, for example, the speed and direction of the user device 110.

[0347] According to an embodiment, the user equipment 110 is configured to notify the serving cell 310 only with a failure indication in case of an erroneous handover configuration and to provide a detailed report only upon request by the serving cell 310 .

[0348] According to an embodiment, the user equipment 110 may be configured to be triggered by the serving cell 310 to provide measurement data.

[0349] According to an embodiment, the user equipment 110 is configured to be triggered by the serving cell 310 to provide measurement reports and / or measurement data, thereby giving information about which triggers led to one or more previous handovers.

[0350] According to an embodiment, the configuration data 1100 has an expiration time, after which another configuration and / or a preconfiguration or a default configuration is used.

[0351] The contention-free RACH preamble is only reserved for a certain time. Then, a different preamble is used and / or a default contention-based RACH procedure is used.

[0352] According to an embodiment, the user equipment 110 is configured to exchange context information with other nodes of the cellular network.

[0353] Other nodes of the cellular network may be described as any one of the following embodiments.

[0354] The embodiments described herein may relate to a transceiver and may be particularly explained in conjunction with a user equipment (UE). The embodiments are not limited to UEs, but relate to, but are not limited to, other types of transmitters or transceivers, such as a transceiver including at least one of the following:

[0355] User equipment;

[0356] Mobile or fixed base stations,

[0357] Mobile terminals,

[0358] Fixed terminal,

[0359] Cellular IoT-UE,

[0360] ·In-vehicle UE,

[0361] Group Leader UE (GL),

[0362] IoT or narrowband IoT (NB-IoT) devices,

[0363] Ground vehicles,

[0364] Aircraft,

[0365] Drones,

[0366] Mobile base stations,

[0367] Roadside Unit (RSU),

[0368] Buildings, and

[0369] • Any other item and / or device (such as a sensor or actuator) having a network connection that enables the item and / or device to communicate using a wireless communication network.

[0370] For example, a mobile or fixed base station may include one or more of the following:

[0371] Macro cell base stations,

[0372] Small cell base stations,

[0373] The central unit of the base station,

[0374] Distributed units of base stations,

[0375] Roadside units,

[0376] UE,

[0377] Group Leader (GL),

[0378] ·relay,

[0379] Remote radio head,

[0380] AMF,

[0381] ·SMF,

[0382] Core network entities,

[0383] Mobile edge computing entities,

[0384] Network slicing in NR or 5G core environments, and

[0385] Any transmit / receive point TRP that enables an item or device to communicate using a wireless communication network, the item or device having a network connection for communicating using the wireless communication network.

[0386] Another embodiment of the cellular network 130 supports conditional switching and is configured to: for one or more predetermined user equipments 110, preemptively prepare for conditional switching of the user equipment 110 to one or more corresponding target cells 120 identified by the cell identifier for each of the one or more target cells 120 of the cellular network 130 of the one or more predetermined user equipments 110.

[0387] The cellular network 130 is further configured to send configuration data to the user equipment 110, the configuration data describing, for each cell, the conditions for triggering a handover to the respective cell.

[0388] The cellular network 130 proactively prepares the user equipment 110 of the present invention for handover to the corresponding cell, or only prepares for future handover to the corresponding cell that may be performed by the user equipment. The proactive preparation may involve assigning one of the available IDs to the user equipment. For example, the ID is included in the user equipment separate part 1150 of the configuration data 1100.

[0389] For example, preemptive preparation can include

[0390] Transfer and storage of user context, such as RRC context, and / or

[0391] A reserved user ID, such as RNTI, and / or

[0392] · Reserve RACH preamble, and / or

[0393] Reserve resources, and / or

[0394] · routing and / or copying packets to one or more prepared target cells, and / or

[0395] Prepare edge cloud capabilities, and / or

[0396] Check and / or prepare for QoS of service operation.

[0397] According to an embodiment, the cellular network is configured to notify the serving cell of the expiry time of the conditional handover from the target cell.

[0398] According to an embodiment, the cellular network is configured to include into the configuration data information about trigger conditions based on which the user equipment should perform a conditional handover to the one or more cells.

[0399] According to an embodiment, the cellular network is configured to include common configuration data into the configuration data that may be covered by the triggering conditions.

[0400] According to an embodiment, the preferred target cell configuration data and / or the configuration data about the target cell with the first preference include different trigger conditions compared to the backup target cell configuration data and / or the configuration data about the target cell with the second preference. The trigger conditions of the backup target cell configuration data and / or the configuration data about the target cell with the second preference include the following initial trigger conditions: handover failure with the preferred target cell and / or the target cell with the first preference.

[0401] According to an embodiment, the cellular network is configured to notify the UE of a successful handover from a target cell that has performed conditional handover or from a serving cell to a previous target cell to a next target cell so that the next target cell can prepare for handover.

[0402] According to an embodiment, the cellular network is configured to send configuration data to the user equipment, wherein the configuration data may include:

[0403] Physical cell identity, and / or

[0404] RACH preamble, and / or

[0405] RACH opportunity for initial connection, and / or

[0406] A fallback process if the initial connection fails, and / or

[0407] User ID and / or RNTI, and / or

[0408] Trigger thresholds, and / or

[0409] The reference signal to be measured, and / or

[0410] Beam information, and / or

[0411] Average calculation information, and / or

[0412] Target cell configuration, and / or

[0413] · Resource pool configuration or usage / utilization for V2X, and / or

[0414] The physical location of the target cell.

[0415] According to an embodiment, the cellular network is configured to send a request to prepare a handover from a serving cell currently serving the user equipment to target cells, wherein at least one of the target cells is not directly adjacent to the serving cell.

[0416] According to an embodiment, the cellular network is configured to send an answer from the target cell to the serving cell.

[0417] According to an embodiment, the cellular network is configured to: enable the user equipment to trigger an update of configuration data from the serving cell by sending a report, if the user equipment is still connected to the serving cell, the report notifying the serving cell from the user equipment when the user equipment cannot perform a handover to one or more cells, and after the user equipment loses and reconnects to the cellular network, the report notifying the new serving cell from the user equipment of an erroneous handover configuration.

[0418] According to an embodiment, the cellular network is configured to enable the user equipment to trigger the update of the configuration data from the serving cell by sending a report, which may include

[0419] Handover failure indication, and / or

[0420] Location information of the user's device, and / or

[0421] Route information, and / or

[0422] Timestamp information, and / or

[0423] Signal strength measurement data associated with user equipment with location and time information, and / or

[0424] a handover configuration and / or a handover context configuration and / or information about a cell in which the handover context configuration is stored, and / or

[0425] information about the last cell to which the user equipment was connected and the identity of the user equipment in that last cell, and / or

[0426] • Information about the cell to which the user equipment is expected to perform a handover.

[0427] According to an embodiment, after the user equipment loses and reconnects to the cellular network, the cellular network is configured to notify the previous serving cell of the reconnection and / or notify new handover and / or new context information from the new serving cell, and / or notify the previous one or more cells of the intended user equipment of the reconnection to release resources reserved for the user equipment.

[0428] According to an embodiment, the cellular network is configured to inform the serving cell only by a failure indication from the user equipment in case of an erroneous handover configuration and to provide a detailed report only upon request by the serving cell.

[0429] According to an embodiment, the cellular network is configured to trigger the user equipment to provide measurement data and / or measurement data from a serving cell.

[0430] According to an embodiment, the cellular network is configured to check: checking a trigger condition related to conditional handover for an unconfigured target cell from a user equipment, and if the unconfigured target cell is a suitable handover candidate, notifying the cellular network of the suitable handover candidate from the user equipment through the source cell.

[0431] According to an embodiment, the cellular network is configured to initiate a handover from the user equipment to an unconfigured cell if a triggering condition for the conditional handover is applicable to the unconfigured cell.

[0432] Implementing an alternative

[0433] Depending on certain implementation requirements, embodiments of the present invention may be implemented in hardware or software. The implementation may be performed using a digital storage medium, such as a floppy disk, DVD, Blu-ray, CD, ROM, PROM, EPROM, EEPROM, or flash memory, having electronically readable control signals stored thereon that cooperate (or are capable of cooperating) with a programmable computer. Thus, the digital storage medium may be computer readable.

[0434] Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system.

[0435] The devices described herein may be implemented using hardware devices, or using computers, or using a combination of hardware devices and computers.

[0436] The apparatus described herein or any component of an apparatus described herein may be implemented at least partially in hardware and / or software.

[0437] The embodiments described herein are only used to illustrate the principles of the present invention. It should be understood that modifications and variations of the arrangements and details described herein will be apparent to other persons skilled in the art. Therefore, it is intended to be limited only by the scope of the appended patent claims, rather than by the specific details presented by the description and explanation of the embodiments herein.

Claims

1. A user equipment (110) supporting conditional handover to a cell (120) of a cellular network (130), the user equipment (110) being configured to: receiving (140) configuration data (110) for configuring a plurality of conditional handovers as a sequence from the cellular network, the configuration data indicating conditions for triggering (160) a conditional handover to any of a plurality of target cells (120) of the cellular network, and checking (150) the condition for applicability and triggering the conditional switching if applicable, in, The user equipment is configured to trigger a conditional handover available to the user equipment within a limited time interval indicated in the configuration data.

2. The user equipment according to claim 1, configured to: after completing (230, 350) the conditional handover, delete (210) the first part of the configuration data and retain the second part of the configuration data.

3. The user equipment according to claim 2, in, said first portion of said configuration data relates to a completed handover, and Therein, the second part of the configuration data relates to a handover that has not yet been completed. The user equipment according to claim 1 , configured to continue the checking after a first triggering of the conditional switching.

5. The user equipment according to claim 1, configured to: triggering the conditional handover by sending a signal (160) to the target cell, and The conditional handover is accomplished (230, 350) by receiving a signal (170) from the target cell.

6. The user equipment according to claim 1, in, The first trigger relates to a conditional handover from a first cell to a second cell, and continuing the checking comprises checking conditions regarding a conditional handover from the second cell to any other cell other than the first cell and / or the target cell.

7. The user equipment according to claim 1, wherein: The configuration data includes a start time and an expiration time of the limited time interval.

8. The user equipment according to claim 7, wherein: The limited time interval may be periodic or limited to a single time.

9. The user equipment according to claim 6, wherein: The configuration data includes more than one periodic time interval and / or limited time interval allocated to different target cells.

10. The user equipment according to claim 1, wherein: The configuration data includes preferred target cell configuration data and / or backup target cell configuration data, or indicates a preference regarding conditional handover to the target cell.

11. The user equipment according to claim 1, wherein: The configuration data includes configuration data of target cells ranked by preference.

12. The user equipment according to claim 10, wherein: the configuration data regarding the preferred target cell and / or regarding the target cell with the first preference comprises different conditions than the configuration data regarding the backup target cell and / or regarding the target cell with the second preference, The conditions of the backup target cell configuration data and / or the configuration data of the target cell having the second preference include the following initial conditions: the handover with the preferred target cell and / or the target cell having the first preference fails.

13. The user equipment according to claim 1, wherein: The configuration data includes information on an order of target cells according to which the user equipment intends to perform the conditional handover.

14. The user equipment of claim 1, configured to update (320) the configuration data according to a configuration update (325) received from the cellular network.

15. The user equipment according to claim 14, wherein: The configuration update comprises a new version of the configuration data and / or comprises only changed portions of the configuration data.

16. The user equipment according to claim 14, wherein: The configuration update changes the plurality of target cells from a first set of cells to a second set of cells in such a manner that an intersection of the first set and the second set includes the plurality of target cells.

17. The user equipment according to claim 1, configured to: A first portion of the configuration data is received via a broadcast or groupcast or multicast transmission (1130), and a second portion of the configuration data is received via a unicast transmission (1150).

18. The user equipment according to claim 1, wherein The first part of the configuration data includes group-specific parameters or common parameters (1130), and The second portion of the configuration data includes user specific parameters or individual parameters (1150).

19. The user equipment according to claim 18, wherein: The first portion of the configuration data is overwritten by the second portion of the configuration data.

20. The user equipment according to claim 17, wherein The second part of the configuration data comprises: Identification information related to the identifier of the user equipment and / or the RACH preamble code identifier and / or the physical resource reservation in the target cell.

21. The user equipment according to claim 17, configured to: Checking whether the second part of the configuration data comprises: identification information related to the identification of the user equipment and / or the RACH preamble code identification and / or the physical resource reservation in the target cell, and If not included, the current identification information of the user equipment is used for the identification of the user equipment and / or the default RACH resource pool and / or the random or default RACH preamble code identification and / or the default physical resource reservation.

22. The user equipment according to claim 17, wherein The first part and / or the second part of the configuration data include: A separate activation message indicates to the user equipment that the configuration data is active for the user equipment.

23. The user equipment according to claim 17, wherein The first part and / or the second part of the configuration data comprises: The target cell configuration information indicates to the user equipment a subsequent target cell configuration to be applied after switching to the target cell.

24. The user equipment according to claim 17, configured to: Checking whether the first part and / or the second part of the configuration data comprises: target cell configuration information, indicating to the user equipment a subsequent target cell configuration to be applied after switching to the target cell, and If not included, the serving source cell (310) configuration information is taken over when the handover is triggered.

25. The user equipment of claim 17, wherein The first portion of the configuration data comprises: • The physical cell identity associated with the target cell, and / or • Target cell configuration parameters, and / or • RACH preamble, and / or • RACH opportunities for initial connection, and / or • a fallback process if the initial connection fails, and / or • The triggering threshold, number and event of the condition indicating the conditional switch to be executed, and / or • the reference signal to be measured, and / or • Beam information, and / or • The physical location of the target cell.

26. The user equipment according to claim 17, configured to: Checking whether the update of the first portion of the configuration data includes information about: • The physical cell identity associated with the target cell, and / or • Target cell configuration parameters, and / or • RACH preamble, and / or • RACH opportunities for initial connection, and / or • a fallback process if the initial connection fails, and / or • The triggering threshold, number and event of the condition indicating the conditional switch to be executed, and / or • the reference signal to be measured, and / or • Beam information, and / or • the physical location of the target cell, If not included, the corresponding information in the current version of the first part is taken over and / or the corresponding default information is taken over.

27. The user equipment according to claim 25 or 26, wherein: The target cell configuration parameters include frequency or carrier bandwidth.

28. The user equipment according to claim 1, configured to: receive configuration data, wherein the configuration data comprises: • Physical cell identity, and / or • RACH preamble, and / or • RACH opportunities for initial connection, and / or • a fallback process if the initial connection fails, and / or • User ID and / or RNTI, and / or • The triggering threshold, number and event of the condition indicating the conditional switch to be executed, and / or • the reference signal to be measured, and / or • Beam information, and / or • Target cell configuration information, and / or • Resource pool configuration or usage for V2X, and / or • The physical location of the target cell.

29. The user equipment according to claim 1, configured to: receive configuration data, if the predetermined target cell indicates to the cellular network that continuity of the preparation of the conditional handover is unreliable, wherein, If the predetermined target cell is adjacent to one or more first target cells adjacent to each other and adjacent to one or more second target cells adjacent to each other but not adjacent to the first target cell, the configuration data may or may not include information about: • The expected time of a conditional switch interrupt, and / or • Predetermined target cell, and / or • a statement that a certain service and / or QoS flow and / or logical channel and / or radio bearer is not supported in the target cell, and / or • Network slicing is not supported.

30. The user equipment according to claim 1, configured to trigger an update (380) of configuration data from a serving source cell (310) by sending a report, If the user equipment is still connected to the serving source cell, the report informs the serving source cell when the user equipment cannot perform a handover to one or more target cells, or After the user equipment loses and reconnects to the cellular network, the report informs a new serving source cell of an erroneous handover configuration.

31. The user equipment according to claim 30, wherein: The report includes: • Handover failure indication, and / or • Location information of the user equipment, and / or • Route information, and / or • Timestamp information, and / or • Signal strength measurements associated with physical cell identities, and / or • a handover configuration and / or a handover context configuration and / or information about a target cell in which the handover context configuration is stored, and / or • information about the last cell to which the user equipment was connected and the identity of the user equipment in the last cell, and / or • Information about the target cell to which the user equipment is expected to perform a handover.

32. The user equipment according to claim 1, configured to: In case of erroneous handover configuration, only the serving cell is notified by a failure indication, and Detailed reports are provided only upon request by the serving source cell.

33. The user equipment according to claim 1, configured to: The provision of measurement data is triggered by the serving source cell.

34. The user equipment according to claim 1, configured to: The provision of measurement reports and / or measurement data is triggered by the serving source cell, giving information about which conditions led to one or more previous handovers.

35. The user equipment according to claim 1, configured to: checking conditions related to conditional handover to an unconfigured target cell, and In the case where an unconfigured target cell is a suitable handover candidate, Notifying the cellular network of the suitable handover candidate via the serving source cell, in, The user equipment is configured to initiate a handover to an unconfigured cell if a condition of the conditional handover is applicable to the unconfigured cell.

36. The user equipment according to claim 1, wherein: The configuration data has an expiration time after which another configuration and / or a preconfiguration or a default configuration is used.

37. The user equipment according to claim 36, wherein: The expiry time exceeds the radio link failure, or the expiry time starts after the radio link failure.

38. The user equipment of claim 1, configured to exchange context information with other nodes of a cellular network.

39. A cellular network (130) supporting conditional handover, configured to: for one or more predetermined user equipment (110), for each of one or more target cells (120) of the cellular network for the one or more predetermined user equipment, preemptively preparing a conditional handover of the user equipment to the one or more corresponding target cells, and Sending configuration data for configuring a plurality of conditional handovers as a sequence to the user equipment, the configuration data describing, for each cell, a condition for triggering handover to the corresponding cell, in, The cellular network is configured to proactively prepare a predetermined user equipment and / or a predetermined target cell for the conditional handover within a limited time interval.

40. The cellular network of claim 39, configured to: After completing the conditional switch deleting a first portion of the configuration data sent to the user equipment while retaining a second portion of the configuration data sent to the user equipment for continuous conditional switching, and Predetermined cells other than the predetermined cell to which the user equipment has performed handover are retained among the predetermined cells preemptively prepared for handover of the user equipment.

41. A cellular network according to claim 40, wherein said first portion of said configuration data relates to a completed handover, and The second portion of the configuration data relates to a handover that has not yet been completed.

42. The cellular network of claim 39, wherein: The cellular network is configured to reserve predetermined cells other than the predetermined cell in which the user equipment actually performs handover, among the predetermined cells prepared in advance for handover of the user equipment.

43. The cellular network of claim 39, configured to: triggering the conditional handover from the user equipment by sending a signal from the user equipment to a target cell, and sending a signal from the target cell to the user equipment, and The conditional handover is completed by the user equipment after receiving the signal from the target cell.

44. The cellular network of claim 39, wherein: The limited time interval may be periodic or limited to a single time.

45. The cellular network of claim 39, configured to notify a serving source cell from the target cell of an expiry time of the conditional handover.

46. ​​A cellular network according to claim 39, configured to determine the end of the limited time interval by an expiry time at or before the time the configuration data is sent.

47. A cellular network according to claim 46, configured to: After said expiry time of said configuration data another configuration and / or a preconfiguration or a default configuration is used.

48. A cellular network according to claim 46, wherein: The expiry time exceeds the radio link failure, or the expiry time starts after the radio link failure.

49. A cellular network according to claim 39, configured to include information about a start time and about an expiry time into the configuration data.

50. The cellular network of claim 39, configured to: upon detecting that the route of the user equipment deviates from the expected future route, ending the limited time interval, and / or The limited time interval is adjusted according to the actual execution of the handover.

51. The cellular network of claim 50, configured to: receiving information about the expected future route of the user equipment from: User entity, or the cellular network and a device other than the user equipment, Alternatively, the expected future route of the user equipment is determined.

52. The cellular network of claim 50, configured to: selecting one or more target cells along the expected future route of the user equipment; and The one or more target cells are preconfigured in a manner corresponding to the configuration data.

53. A cellular network according to claim 39, configured to include in the configuration data information about conditions based on which the user equipment should perform a conditional handover to the one or more target cells.

54. A cellular network according to claim 39, configured to include common configuration data that may be covered by the condition into the configuration data.

55. A cellular network according to claim 39, configured to include preferred target cell configuration data and / or backup target cell configuration data into the configuration data.

56. A cellular network according to claim 39, configured to include preference ranked target cell configuration data into the configuration data.

57. A cellular network according to claim 55, wherein the preferred target cell configuration data and / or the configuration data regarding the target cell having the first preference comprises different conditions than the alternate target cell configuration data and / or the configuration data regarding the target cell having the second preference, in, The conditions of the backup target cell configuration data and / or the configuration data of the target cell with the second preference include the following initial conditions: handover with the preferred target cell and / or the target cell with the first preference fails.

58. The cellular network of claim 39, configured to include information about an order of target cells according to which the user equipment performs the conditional handover into the configuration data.

59. The cellular network of claim 39, configured to: The user equipment is notified of a successful handover to a previous target cell from a target cell to which a conditional handover has been performed or from a serving source cell to a next target cell so that the next target cell can prepare for the handover.

60. The cellular network of claim 39, configured to: Updates of the configuration data are sent to the user equipment at an update rate that is less than a handover rate at which the user equipment performs handovers to the one or more target cells.

61. A cellular network according to claim 60, wherein: The update comprises a new version of the configuration data and / or comprises only changed parts of the configuration data.

62. The cellular network of claim 60, configured to cause the updating to change the one or more target cells from a first set of cells to a second set of cells in such a way that an intersection of the first set and the second set includes the one or more target cells.

63. A cellular network according to claim 39, configured such that the one or more target cells comprise a sequence of cells in which consecutive cells are exclusively adjacent to each other.

64. The cellular network of claim 39, configured to: sending the first part of the configuration data via a broadcast or groupcast or multicast transmission, and The second portion of the configuration data is sent via a unicast transmission.

65. A cellular network according to claim 64, wherein said first part of said configuration data sent via broadcast or groupcast or multicast transmission comprises group specific parameters or common parameters, and The second portion of the configuration data sent via unicast transmission comprises user specific parameters or individual parameters.

66. The cellular network of claim 39, configured to send configuration data to the user equipment, wherein the configuration data comprises • Physical cell identity, and / or • RACH preamble, and / or • RACH opportunities for initial connection, and / or • a fallback process if the initial connection fails, and / or • User ID and / or RNTI, and / or • Trigger thresholds, and / or • the reference signal to be measured, and / or • Beam information, and / or • Target cell configuration information, and / or • Resource pool configuration or usage for V2X, and / or • The physical location of the target cell.

67. The cellular network of claim 39, configured to: sending a request for preparing a handover from a serving source cell currently serving the user equipment to a target cell, in, At least one of the target cells is not directly adjacent to the serving source cell.

68. The cellular network of claim 67, configured to: A reply is sent from the target cell to the serving source cell.

69. A cellular network according to claim 68, wherein: The reply includes configuration parameters, and the cellular network is configured to: Information about the configuration parameters is included in the configuration data.

70. The cellular network of claim 68, configured to: The one or more target cells are selected from the target cells based on the reply.

71. The cellular network of claim 68, configured to: Sending a confirmation message to the one or more target cells, the confirmation message including: Confirmation of the conditional switching, and / or Information about the expected time of arrival of the user's equipment.

72. A cellular network according to claim 71, wherein The confirmation message also includes • the identity of the one or more target cells, and / or • The services and / or slices that the intended user equipment is currently using and / or is expected to use in the new cell.

73. The cellular network of claim 39, configured to: Information about the expected time of arrival of the user equipment and a request to prepare for the handover is provided to the target cell.

74. The cellular network of claim 39, configured to: If the confirmation message from the predetermined target cell is negative, and the predetermined target cell is adjacent to one or more first target cells that are adjacent to each other and to one or more second target cells that are adjacent to each other but not to the first target cell, then including an indication of unreliable continuity of conditional handover preparation into the configuration data, the configuration data including or excluding information about: • The expected time of a conditional switch interrupt, and / or • the predetermined target cell, and / or • a statement that a certain service and / or QoS flow and / or logical channel and / or radio bearer is not supported in the target cell, and / or • Network slicing is not supported.

75. The cellular network of claim 39, configured to send information related to actual execution of a handover between two of the one or more target cells to other cells of the one or more target cells other than the two cells, in, The information includes: • the time at which the switch was actually performed, and / or • the time at which the user equipment is expected to be in any of the other cells, and / or • The services and / or slices that the user equipment is currently using or is expected to use in the future cell, and / or • the speed at which the user equipment is moving, and / or • Past neighborhood change history, and / or • statistical data on business activities, and / or • The updated identity of the user equipment and / or a mapping with the identity of the user equipment in the previous cell.

76. The cellular network of claim 39, configured to cause the user equipment to trigger an update of configuration data from a serving source cell by sending a report, If the user equipment is still connected to the serving source cell, the report notifies the serving source cell from the user equipment when the user equipment is unable to perform a handover to one or more cells, or The report informs a new serving source cell of an erroneous handover configuration from the user equipment after the user equipment loses and reconnects to the cellular network.

77. The cellular network of claim 76, configured to cause the user equipment to trigger an update of configuration data from the serving source cell by sending a report, the report comprising: • Handover failure indication, and / or • Location information of the user equipment, and / or • Route information, and / or • Timestamp information, and / or • Signal strength measurement data associated with said user equipment with location and time information, and / or • a handover configuration and / or a handover context configuration and / or information about a cell in which the handover context configuration is stored, and / or • information about the last cell to which the user equipment was connected and the identity of the user equipment in the last cell, and / or • Information about the cell to which the user equipment is expected to perform a handover.

78. The cellular network of claim 76, configured to: After the user equipment loses and reconnects to the cellular network: Notifying the previous serving cell of the reconnection and / or notifying the new handover and / or new context information from the new serving source cell, and / or The previous one or more cells where the user equipment was expected are notified of the reconnection to release resources reserved for the user equipment.

79. The cellular network of claim 76, configured to: in case of an erroneous handover configuration, notifying the serving source cell from the user equipment only by a failure indication, and Detailed reports are provided only upon request by the serving source cell.

80. The cellular network of claim 76, configured to trigger the user equipment to provide measurement reports and / or measurement data from the serving source cell.

81. The cellular network of claim 39, configured to: checking, from the user equipment, conditions related to conditional handover to an unconfigured target cell, and In the case where an unconfigured target cell is a suitable handover candidate, Notifying the cellular network of the suitable handover candidate from the user equipment via a serving source cell, in, The cellular network is configured to initiate a handover from the user equipment to the unconfigured cell if a condition of the conditional handover is applicable to the unconfigured cell.

82. The cellular network of claim 39, configured to exchange context information of the user equipment between cellular network nodes.

83. The cellular network of claim 39, wherein the cellular network is a cloud radio access network, wherein: Control plane functions are centralized.

84. The cellular network of claim 39, comprising: An LTE network connected to the Evolved Packet Core via an X2 and / or S1 interface, and / or LTE / NR network connected to the 5G Core via Xn and / or NG-C interfaces.

85. A method for supporting conditional switching, comprising: The user equipment receives (140) configuration data (1100) for configuring a plurality of conditional handovers in a sequence from a cellular network, the configuration data indicating conditions for triggering (160) a conditional handover to any of a plurality of target cells (120) of the cellular network, and the user equipment checks (150) the condition via the user equipment for applicability and triggers the conditional switching if applicable, Wherein, triggering the conditional switching is available to the user equipment within a limited time interval indicated in the configuration data.

86. A method for supporting conditional switching, comprising: for one or more predetermined user equipments (110), preemptively preparing, for each of one or more target cells (120) of a cellular network of the one or more predetermined user equipments, a conditional handover of the user equipment to the one or more corresponding target cells, and Sending configuration data for configuring a plurality of conditional handovers as a sequence to the user equipment, the configuration data describing, for each cell, a condition for triggering a handover to the corresponding cell, The conditional switching in the step of preemptively preparing the reserved user equipment and / or the reserved target cell is for a limited time interval.

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