Conditional handover in handover command

Abstract

Methods and apparatuses for conditional handover in handover commands are disclosed. In one embodiment, a wireless device, WD, is configured to receive a request to perform a mobility procedure for the wireless device from a source cell supported by a source network node to a target cell supported by a network node, the request comprising a current configuration for the wireless device in the source cell; upon receiving the request, determine a conditional reconfiguration for the wireless device; and send the conditional reconfiguration and a radio resource control, RRC, reconfiguration for the wireless device, the RRC reconfiguration being associated with the requested mobility procedure from the source cell to the target cell supported by the network node, and the conditional reconfiguration being associated with a target candidate cell determined by the network node.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to wireless communications, and more specifically to conditional handover. BACKGROUND

[0002] Mobility in RRC CONNECTED in LTE and NR

[0003] An RRC CONNECTED wireless device (WD), e.g., a user equipment (UE) in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (also known as Evolved Universal Terrestrial Radio Access (EUTRA)), can be configured by a network node to perform measurements, and upon triggering of a measurement report, the network node can send a handover (HO) command to the WD (RRConnectionReconfiguration in LTE with a field named mobilityControlInfo, and RRCReconfiguration in 3GPP New Radio (NR) (also known as “5G”) with a reconfigurationWithSync field).

[0004] These reconfigurations are actually prepared by the target cell (or more specifically the network node supporting the target cell) upon request from the source node (over the X2 interface in case of EUTRA-EPC or over the Xn interface in case of EUTRA-5th Generation (5GC) or NR) and taking into account the existing / current Radio Resource Control (RRC) configuration the WD has with the source cell, which is provided in the inter-node request. This reconfiguration provided by the target network node contains, among other parameters, all the information the WD needs to access the target cell, e.g., random access configuration, a new C-RNTI (Cell Radio Network Temporary Identifier) assigned by the target cell and security parameters enabling the WD to compute new security keys associated with the target cell, so that the WD can send a handover complete message upon accessing the target cell over Signaling Radio Bearer 1 (SRB1 (encrypted and integrity protected) based on the new security keys.

[0005] Figure 1 is an example diagram outlining an example of flow signaling between a WD, a source network node (NN) and a target network node (NN) during a handover procedure. For example, the flow signaling can include the following:

[0006] 1. The WD sends a measurement report;

[0007] 2. The source NN makes a handover (HO) decision;

[0008] 3. The source NN sends the HO request to the target NN;

[0009] 4. The target NN performs admission control;

[0010] 5. The target NN sends the HO request acknowledgement;

[0011] 6. The Uu handover trigger is performed between the WD and the source NN;

[0012] 7. The source NN sends the sequence number (SN) status transfer to the target NN;

[0013] 8. The WD detaches from the old cell and synchronizes to the new cell;

[0014] 9. The source NN transfers buffered and ongoing users to the target NN;

[0015] 10. The source NN forwards user data to the target NN;

[0016] 11. The target NN buffers user data from the source NN; and

[0017] 12. The WD synchronizes to the new cell and completes the RRC handover procedure.

[0018] In both LTE and NR, there are some principles for handover (or more general term, mobility in RRC CONNECTED). Examples of these principles include:

[0019] a) Mobility in RRC CONNECTED is network-based, as the network node has the best information about the current situation (e.g. load conditions, resources in different nodes, available frequencies, etc.). The network can also consider the situation of many WDs in the network for resource allocation perspective.

[0020] b) The network prepares the target cell before the WD accesses it. The source network node (NN) provides the WD with the RRC configuration to be used in the target cell, including the signaling radio bearer 1 (SRB1) configuration to send the HO complete message.

[0021] c) The WD is identified by the target NN on the medium access control (MAC level) from message 3 (MSG.3) with a target C-RNTI, i.e. the target, for the HO complete message. Thus, there is no context fetching unless a failure occurs.

[0022] d) To speed up the handover, the network node provides information about how to access the target, e.g. random access channel (RACH) configuration, so the WD does not have to acquire system information (SI) before the handover.

[0023] e) The WD can be provided with contention-free random access (CFRA) resources, i.e. in this case the target NN identifies the WD from the preamble (MSG.1). The principle behind this is that the procedure can always be optimized by dedicated resources. It can be a bit tricky in conditional HO (CHO) since there is uncertainty about the final target cell / NN as well as timing.

[0024] f) Prepare security before the WD accesses the target cell, e.g. refresh keys before sending the RRC Connection Reconfiguration Complete message, based on new keys and encryption and integrity protection to enable verification of the WD in the target cell.

[0025] g) Support both full and delta reconfiguration to enable minimization of the HO command.

[0026] Mobility robustness work item and conditional HO in Rel-16 for LTE and NR

[0027] Two new work items for mobility enhancements in LTE and NR started in 3rd Generation Partnership Project (3GPP) Release 16 (Rel-16). One of the goals of the work items is to improve the robustness at handover, i.e. the quality of the handover, and to reduce the interruption time at handover.

[0028] One problem related to the robustness at handover is that the HO command (RRCConnectionReconfiguration with MobilityControlInfo, and RRCReconfiguration with reconfigurationWithSync field) is typically sent when the radio conditions for the WD are already quite bad. If the message is segmented or there are retransmissions, it can result in that the HO command does not reach the WD in time.

[0029] Different solutions to increase the mobility robustness have been discussed in the past in LTE and NR. One solution discussed in NR is called “conditional handover” or “early handover command”. To avoid the undesired dependency on the serving radio link at the time (and radio conditions) when the WD can implement / execute the handover, the possibility to provide the WD with RRC signaling for handover earlier can be provided. To achieve this, the HO command can be associated with a condition, e.g. based on radio conditions that can be similar to the radio conditions associated with an A3 event, where a given neighbor becomes X decibels (dB) better than the target cell. Once the condition is met, the WD can execute the handover according to the provided handover command.

[0030] Such condition can for example be that the quality of the target cell or beam becomes X dB stronger than the serving / source cell. The threshold Y used in the previous measurement reporting event can then be chosen to be lower than the X threshold in the handover execution condition. This allows the NN supporting the serving / source cell to prepare for handover already upon receiving the early measurement report and provide the RRCConnectionReconfiguration with mobilityControlInfo while the radio link between the source cell and the WD is still stable. The execution of the handover is performed at a later point in time (and threshold) which is considered to be optimal for the execution of the handover.

[0031] Figure 2 An example signaling flow for conditional handover involving only the WD supporting the source NN of the serving / source cell and the target NN supporting the target cell is depicted. For example, the flow signaling can include the following:

[0032] 1. The WD sends a measurement report with a low threshold Y compared to the X threshold;

[0033] 2. The source NN makes a HO decision based on the early measurement report;

[0034] 3. The source NN sends an early HO request to the target NN;

[0035] 4. The target NN accepts the HO request and builds an RRC configuration for the WD;

[0036] 5. The target NN sends a HO acknowledgement including the RRC configuration to the source NN;

[0037] 6. The source NN sends a conditional HO command with the high threshold X to the WD;

[0038] 7. The WD triggers the pending conditional HO when the measurements satisfy the HO condition;

[0039] 8. The WD synchronizes to the target cell and performs a random access to the target cell;

[0040] 9. The WD sends a HO acknowledgement to the target NN;

[0041] 10. The target NN sends a HO completed message to the source NN; and

[0042] 11. The target NN can send user plane (UP) data to the WD in the target cell.

[0043] In practice, there can typically be many cells or beams that the WD has as possible candidate cells based on its previous radio resource management (RRM) measurement reports. The network node can then have the freedom to issue conditional handover commands to some of these candidates. The RRCConnectionReconfiguration of each of those candidates can differ, e.g., in terms of HO execution conditions (reference signals (RSs) to be measured and thresholds to be exceeded) and in terms of random access (RA) preambles to be transmitted when the conditions are fulfilled.

[0044] When the WD evaluates the conditions associated with the conditional HO command, the WD can continue to operate in the source cell according to its current RRC configuration, i.e., the conditional HO command is not applied. When the WD determines that the conditions are fulfilled, the WD disconnects from the serving / source cell, applies the conditional HO command and connects to the target cell. At least some of these conditional HO steps (e.g., disconnecting from the serving cell, applying the HO and connecting to the target cell) can be considered equivalent or similar to current instantaneous handover execution.

[0045] For conditional handover, the following has been considered:

[0046] Considerations:

[0047] - The source cell (such as, e.g., the source network node) decides the conditions for execution / implementation of CHO.

[0048] - The source cell (such as, e.g., the source network node) adds the conditions for execution of CHO to an RRC message sent to the WD.

[0049] - Multiple CHO candidate cells can be sent in one or more RRC messages. Further study (FFS) signaling details. FFS how CHO execution is handled.

[0050] - CHO execution does not trigger measurement reporting.

[0051] - Cell level CHO execution conditions can be specified (A3 / A5, if no explicit reason, other events will not be specified).

[0052] Other considerations:

[0053] - Separate CHO execution conditions can be configured for each individual candidate cell.

[0054] - CHO execution conditions are defined by measurement identities that identify measurement configurations. (FFS in stage 3, which parts of the measurement configuration are used for CHO triggering).

[0055] - As a baseline CHO can be triggered based on a condition containing a single event, a single RS type, a single quantity.

[0056] - The number of individual triggers can be configured as RSRP, RSRQ or RS-SINR

[0057] - The single RS type can be configured as SSB or CSI-RS

[0058] FFS if multiple triggering conditions are needed.

[0059] There are other considerations:

[0060] - Deconfiguration of CHO candidates by RRC signaling (we do not introduce timer-based mechanisms for WD to deconfigure CHO candidates)

[0061] - Baseline, release the configuration of all CHO candidates upon successful (any) handover completion (sending completion message to target cell).

[0062] FFS if it is possible to keep CHO candidates after HO.

[0063] Further considerations:

[0064] - Upon reception of the configuration of CHO candidates, the WD can not stop T310 and can not start T304

[0065] - When the WD starts to perform conditional handover towards the target cell, it will stop timer T310 and start a similar timer T304. (Phase 3 details if we reuse T304 or define a new timer)

[0066] Working assumptions based on the above further considerations:

[0067] - At RLF, the WD performs cell selection and if the selected cell is a CHO candidate, the WD attempts CHO execution, otherwise it implements re-establishment

[0068] - Upon legacy handover failure (T304 expiry) or failure to access a CHO candidate cell (similar T304 expiry), the WD performs cell selection and if the selected cell is a CHO candidate, the WD attempts CHO execution, otherwise it implements re-establishment.

[0069] Consider that an RRC container can be used to carry the target cell configuration as part of the CHO configuration to be sent to the WD and the source cell is not allowed to change anything from the configuration of the target cell. In addition to this, consider enhancing the existing RRCReconfiguration message to include the conditional handover configuration. SUMMARY

[0070] Some embodiments advantageously provide methods, systems, and devices for conditional handover in handover commands.

[0071] In one embodiment, a method implemented in a network node includes one or more of the following: receiving, from a source network node in a handover, HO, procedure, an HO preparation message, the HO preparation message including a current configuration of a WD in a source cell; determining a conditional handover, CHO, configuration for the WD; and / or sending, to the source network node, a message including the determined CHO configuration.

[0072] In one embodiment, a method implemented in a wireless device, WD, includes one or more of the following: receiving a message, the message being a radio resource control, RRC, reconfiguration message including a conditional handover, CHO, configuration and an indication of a handover, HO, command, the CHO being prepared by a target network node, the HO command being prepared by a source network node; in response to the received message, attempting to access the target network node indicated in the HO command; and / or after accessing the target network node, performing a CHO according to the CHO configuration in the received message.

[0073] According to one aspect of the disclosure, a method implemented at a wireless device, WD, configured to communicate with a network node is provided. The method includes receiving at least one radio resource control, RRC, reconfiguration message, the at least one RRC reconfiguration message including a conditional reconfiguration and an indication that the wireless device is to perform a mobility procedure. The indication that the wireless device is to perform the mobility procedure indicates to perform a mobility procedure from a source cell supported by the network node to a target cell supported by a target network node. The conditional reconfiguration is associated with a target candidate cell corresponding to the target network node.

[0074] In some embodiments of this aspect, the method includes, upon receiving the at least one RRC reconfiguration message, performing the mobility procedure indicated in the received at least one RRC reconfiguration by attempting to access the target cell. In some embodiments of this aspect, the method includes, as a result of accessing the target cell, performing at least one action according to the conditional reconfiguration included in the received at least one RRC reconfiguration. In some embodiments of this aspect, the method includes, as a result of a failure to attempt to access the target cell, selecting a candidate cell associated with a conditional handover and performing a handover of the wireless device to the selected candidate cell. In some embodiments of this aspect, selecting the candidate cell associated with the conditional handover includes, as a result of the failure to attempt to access the target cell, selecting the candidate cell from among at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and the target network node.

[0075] In some embodiments of this aspect, selecting the candidate cell associated with the conditional handover comprises selecting the candidate cell from at least a plurality of candidate cells as a result of a failure to access a target cell, each candidate cell being associated with a respective conditional handover and a network node supporting the source cell. In some embodiments of this aspect, the explicit indication indicates to the wireless device to select the candidate cell from at least one of a first plurality of candidate cells associated with the network node supporting the source cell and a second plurality of candidate cells associated with the target network node as a result of the failure to access the target cell.

[0076] In some embodiments of this aspect, the conditional reconfiguration and the indication to perform the mobility procedure are both included in the same RRC reconfiguration message. In some embodiments of this aspect, the explicit indication indicates to the wireless device to perform the conditional reconfiguration included in the same RRC reconfiguration message only after accessing the target cell according to the indicated mobility procedure in the same RRC reconfiguration message. In some embodiments of this aspect, the conditional reconfiguration and the indication to perform the mobility procedure are prohibited in the same RRC reconfiguration message. In some embodiments of this aspect, the method comprises performing an RRC reestablishment procedure instead of the indicated mobility procedure and the conditional reconfiguration when the conditional reconfiguration and the indication to perform the mobility procedure are both included in the same RRC reconfiguration message.

[0077] In some embodiments of this aspect, the mobility procedure is a handover of the wireless device from the source cell to the target cell. In some embodiments of this aspect, the mobility procedure corresponds to at least one of a request to the wireless device to add and change a primary secondary cell, PSCell. In some embodiments of this aspect, the indication to perform the mobility procedure comprises one of a synchronization reconfiguration field and a mobility control information field included in the at least one RRC reconfiguration message. In some embodiments of this aspect, the method further comprises receiving signaling indicating one of an addition, a modification, and a release of the conditional reconfiguration of the target candidate cell prepared by the target network node.

[0078] In some embodiments of this aspect, the conditional reconfiguration associated with the target candidate cell comprises a trigger condition configuration comprising a set of pointers to at least one measurement identifier, and each measurement identifier of the at least one measurement identifier is associated with at least one trigger condition and an RRC reconfiguration. In some embodiments of this aspect, the method further comprises determining not to send an RRC reconfiguration complete message based at least in part on a presence of the conditional reconfiguration associated with the target candidate cell in the at least one RRC reconfiguration message.

[0079] In another aspect of the disclosure, a method implemented in a network node is provided. The method includes receiving a request to perform a mobility procedure from a source cell supported by a source network node to a target cell supported by the network node, the request including a current configuration of a wireless device in the source cell. The method includes determining, upon receiving the request, to prepare a conditional reconfiguration for the wireless device. The method includes sending the conditional reconfiguration for the wireless device and a radio resource control (RRC) reconfiguration associated with the requested mobility procedure from the source cell to the target cell supported by the network node and the conditional reconfiguration is associated with a target candidate cell determined by the network node.

[0080] In some embodiments of this aspect, the wireless device is to use the conditional reconfiguration upon failing to access the target cell indicated in the requested mobility procedure. In some embodiments of this aspect, the target candidate cell associated with the conditional reconfiguration is selectable by the wireless device for switching the wireless device to the target candidate cell upon failing to access the target cell indicated in the requested mobility procedure. In some embodiments of this aspect, the target candidate cell associated with the conditional reconfiguration is not selectable by the wireless device for switching the wireless device to the target candidate cell upon failing to access the target cell indicated in the requested mobility procedure.

[0081] In some embodiments of this aspect, the mobility procedure is a handover of the wireless device from the source cell to the target cell. In some embodiments of this aspect, the mobility procedure corresponds to at least one of a request to the wireless device to add and change a primary secondary cell (PSCell). In some embodiments of this aspect, determining to prepare the conditional reconfiguration for the wireless device is based at least in part on measurements from the wireless device included in the received request to perform the mobility procedure. In some embodiments of this aspect, preparing the conditional reconfiguration for the wireless device includes sending an RRC reconfiguration for the wireless device to a target candidate network node supporting the target candidate cell and obtaining the conditional reconfiguration from the target candidate network node based at least in part on the sent RRC reconfiguration.

[0082] In some embodiments of this aspect, at least one of the conditional reconfiguration associated with the target candidate cell and the RRC reconfiguration associated with the target cell of the mobility procedure is based at least in part on the received current configuration of the wireless device in the source cell. In some embodiments of this aspect, the method further includes receiving an RRC reconfiguration complete message and, as a result of the received RRC reconfiguration complete message, communicating with the wireless device based on an assumption that the wireless device is operating according to the conditional reconfiguration.

[0083] According to yet another aspect of the disclosure, a wireless device, WD, configured to communicate with a network node is provided. The wireless device comprises processing circuitry. The processing circuitry is configured to cause the wireless device to receive at least one radio resource control, RRC, reconfiguration message comprising a conditional reconfiguration and an indication that the wireless device is to perform a mobility procedure. The indication that the wireless device is to perform the mobility procedure indicates to perform a mobility procedure from a source cell supported by the network node to a target cell supported by a target network node. The conditional reconfiguration is associated with a target candidate cell corresponding to the target network node

[0084] In some embodiments of this aspect, the processing circuitry is further configured to cause the wireless device to perform the mobility procedure indicated in the received at least one RRC reconfiguration by attempting to access the target cell upon receiving the at least one RRC reconfiguration message. In some embodiments of this aspect, the processing circuitry is further configured to cause the wireless device to perform at least one action in accordance with the conditional reconfiguration included in the received at least one RRC reconfiguration as a result of accessing the target cell. In some embodiments of this aspect, the processing circuitry is further configured to cause the wireless device to select a candidate cell associated with a conditional handover and perform a handover of the wireless device to the selected candidate cell as a result of failing to attempt to access the target cell.

[0085] In some embodiments of this aspect, the processing circuitry is configured to cause the wireless device to select the candidate cell associated with the conditional handover by being configured to cause the wireless device to select the candidate cell from at least a plurality of candidate cells as a result of failing to attempt to access the target cell, each candidate cell being associated with a respective conditional handover and the target network node. In some embodiments of this aspect, the processing circuitry is configured to cause the wireless device to select the candidate cell associated with the conditional handover by being configured to cause the wireless device to select the candidate cell from at least a plurality of candidate cells as a result of failing to attempt to access the target cell, each candidate cell being associated with a respective conditional handover and a network node supporting the source cell.

[0086] In some embodiments of this aspect, the explicit indication indicates to the wireless device to select the candidate cell from at least one of a first plurality of candidate cells associated with a network node supporting the source cell and a second plurality of candidate cells associated with the target network node as a result of failing to attempt to access the target cell. In some embodiments of this aspect, the conditional reconfiguration and the indication to perform the mobility procedure are both included in a same RRC reconfiguration message. In some embodiments of this aspect, the explicit indication indicates to the wireless device to perform the conditional reconfiguration included in the same RRC reconfiguration message only after accessing the target cell in accordance with the mobility procedure indicated in the same RRC reconfiguration message.

[0087] In some embodiments of this aspect, the indication to prohibit the conditional reconfiguration and the execution of the mobility procedure are in the same RRC reconfiguration message. In some embodiments of this aspect, the processing circuitry is further configured to cause the wireless device to perform an RRC re-establishment procedure instead of the indicated mobility procedure and the conditional reconfiguration when both the indication to prohibit the conditional reconfiguration and the execution of the mobility procedure are included in the same RRC reconfiguration message. In some embodiments of this aspect, the mobility procedure is a handover of the wireless device from a source cell to a target cell. In some embodiments of this aspect, the mobility procedure corresponds to a request to add and change at least one primary secondary cell, PSCell, for the wireless device.

[0088] In some embodiments of this aspect, the indication to perform the mobility procedure is included in one of a synchronization reconfiguration field and a mobility control information field included in the at least one RRC reconfiguration message. In some embodiments of this aspect, the processing circuitry is further configured to cause the wireless device to receive signaling indicating one of a conditional reconfiguration for adding, modifying, and releasing a target candidate cell prepared by the target network node. In some embodiments of this aspect, the conditional reconfiguration associated with the target candidate cell includes a trigger condition configuration including a set of pointers to at least one measurement identifier, and each measurement identifier of the at least one measurement identifier is associated with at least one trigger condition and an RRC reconfiguration.

[0089] In some embodiments of this aspect, the processing circuitry is further configured to cause the wireless device to determine not to send an RRC reconfiguration complete message based at least in part on a presence of the conditional reconfiguration associated with the target candidate cell in the at least one RRC reconfiguration message.

[0090] According to another aspect of the disclosure, a network node is provided. The network node includes processing circuitry. The processing circuitry is configured to cause the network node to receive a request to perform a mobility procedure for a wireless device from a source cell supported by a source network node to a target cell supported by the network node, the request including a current configuration of the wireless device in the source cell. The processing circuitry is configured to cause the network node to determine, upon receiving the request, to prepare a conditional reconfiguration for the wireless device. The processing circuitry is configured to cause the network node to send the conditional reconfiguration and a radio resource control, RRC, reconfiguration for the wireless device, the RRC reconfiguration being associated with the requested mobility procedure from the source cell to the target cell supported by the network node, and the conditional reconfiguration being associated with a target candidate cell determined by the network node.

[0091] In some embodiments of this aspect, the wireless device will use the conditional reconfiguration after the target cell indicated in the access requested mobility procedure. In some embodiments of this aspect, the target candidate cell associated with the conditional reconfiguration is selectable by the wireless device for switching the wireless device to the target candidate cell upon failure of the target cell indicated in the access requested mobility procedure. In some embodiments of this aspect, the target candidate cell associated with the conditional reconfiguration is not selectable by the wireless device for switching the wireless device to the target candidate cell upon failure of the target cell indicated in the access requested mobility procedure. In some embodiments of this aspect, the mobility procedure is a handover of the wireless device from a source cell to a target cell. In some embodiments of this aspect, the mobility procedure corresponds to at least one of a request to add and change a primary secondary cell, PSCell, for the wireless device.

[0092] In some embodiments of this aspect, the processing circuitry is configured to cause the network node to determine the conditional reconfiguration for the wireless device based at least in part on measurements from the wireless device included in the received request to perform the mobility procedure. In some embodiments of this aspect, the processing circuitry is configured to cause the network node to send an RRC reconfiguration for the wireless device to a target candidate network node supporting a target candidate cell; and obtain a conditional reconfiguration from the target candidate network node, the conditional reconfiguration based at least in part on the sent RRC reconfiguration, by being configured to cause the network node to prepare the conditional reconfiguration for the wireless device.

[0093] In some embodiments of this aspect, at least one of the conditional reconfiguration associated with the target candidate cell and the RRC reconfiguration associated with the target cell of the mobility procedure is based at least in part on a received current configuration for the wireless device in the source cell. In some embodiments of this aspect, the processing circuitry is further configured to cause the network node to receive an RRC reconfiguration complete message; and as a result of the received RRC reconfiguration complete message, communicate with the wireless device based on an assumption that the wireless device is operating according to the conditional reconfiguration. BRIEF DESCRIPTION OF DRAWINGS

[0094] The present embodiments, together with its attendant advantages, will be understood by reference to the following detailed description, taken in connection with the accompanying drawings, wherein:

[0095] Figure 1 is a flowchart illustrating an example handover execution;

[0096] Figure 2 is a flowchart illustrating an example conditional handover execution;

[0097] Figure 3 is a flowchart illustrating another example handover execution;

[0098] Figure 4 is a schematic diagram illustrating an exemplary network architecture of a communication system connected to a host computer via an intermediate network, in accordance with the principles of the present disclosure;

[0099] Figure 5 is a block diagram of a host computer communicating via a network node with a wireless device over a partially wireless connection, in accordance with some embodiments of the present disclosure;

[0100] Figure 6 is a flowchart illustrating an exemplary method for executing a client application at a wireless device in a communication system including a host computer, a network node, and a wireless device, in accordance with some embodiments of the present disclosure;

[0101] Figure 7 is a flowchart illustrating an exemplary method for receiving user data at a wireless device in a communication system including a host computer, a network node, and a wireless device, in accordance with some embodiments of the present disclosure;

[0102] Figure 8 is a flowchart illustrating an exemplary method for receiving user data at a host computer from a wireless device in a communication system including the host computer, a network node, and the wireless device, in accordance with some embodiments of the present disclosure;

[0103] Figure 9 is a flowchart illustrating an exemplary method for receiving user data at a host computer in a communication system including the host computer, a network node, and a wireless device, in accordance with some embodiments of the present disclosure;

[0104] Figure 10 is a flowchart of an exemplary procedure in a network node for configuring a unit, in accordance with some embodiments of the present disclosure;

[0105] Figure 11 is a flowchart of an exemplary procedure in a wireless device for switching a unit, in accordance with some embodiments of the present disclosure;

[0106] Figure 12 is a flowchart of an exemplary handover procedure, in accordance with some embodiments of the present disclosure; and

[0107] Figure 13 is a flowchart of yet another exemplary handover procedure, in accordance with some embodiments of the present disclosure. DETAILED DESCRIPTION

[0108] Using the enhanced RRCReconfiguration for configuring CHO can mean that fields / IEs (information elements) are included with AddMod / Release structure for CHO. However, the network can also use the same message to trigger a handover, where one needs to include a synchronous reconfiguration with information associated to the target cell. The use case not foreseen by existing considerations is whether the target cell in handover wants to prepare a CHO configuration. If following the state-of-the-art specification and assuming implementation of the current protocol, it can be performed as shown in Figure 3 and summarized as follows:

[0109] 1. The WD sends a measurement report to the source NN;

[0110] 2. The source network node processes the measurement report and decides to HO the WD to a target cell supported by the target network node;

[0111] 3. The target network node is capable of CHO and wants to configure CHO to the WD but needs to wait until the WD accesses the target cell;

[0112] 4. The target network node prepares and sends a first RRC reconfiguration in a container for the WD, to be transmitted by the source network node;

[0113] 5. The WD receives the RRC reconfiguration with synchronous reconfiguration from the source network node;

[0114] 6. The WD accesses the target cell and sends an RRC reconfiguration complete message to the target network node;

[0115] 7. After accessing the target cell, the target network node can now send another second RRC reconfiguration to the WD including the CHO configuration prepared by / corresponding to the target network node and possibly associated measurement configuration; and

[0116] 8. The WD can now start performing monitoring of CHO triggering conditions; and

[0117] 9. The WD then sends another second RRC reconfiguration complete message to the target network node.

[0118] Hence, if the target network node is capable of configuring CHO and wants to do so for an incoming WD in a handover procedure (or any other mobility procedure, e.g. primary secondary cell (PSCell) change), the target network node first waits for the WD to access the target cell to then provide a new second reconfiguration containing the CHO configuration in a new message to the WD, which adds signaling. And, the new message can need to include measurement configuration associated to CHO, which would postpone the timing for the WD to start performing measurements for CHO.

[0119] Some embodiments of the present disclosure comprise a method performed by a wireless device (also referred to as a user equipment (UE)) for a reconfiguration procedure, the method comprising one or more of:

[0120] - receiving a message (e.g., RRCReconfiguration) comprising:

[0121] o a conditional reconfiguration (e.g., CHO configuration) associated with a corresponding target candidate cell, the conditional reconfiguration being prepared by a target cell / target network node (each conditional reconfiguration can comprise a triggering condition, an associated RRC reconfiguration to be used by the wireless device upon triggering, and a target candidate cell identifier identifying the target candidate cell);

[0122] o an indication that the WD can perform a mobility procedure (e.g., a synchronization reconfiguration in an RRCReconfiguration message indicating to the WD to perform a handover of the WD from a source cell to a target cell). The indication can be the presence of a synchronization reconfiguration field within a CellGroupConfig;

[0123] - upon reception of the message:

[0124] o the WD first performs the mobility procedure, i.e., the WD accesses the target cell indicated in the mobility procedure indication (e.g., HO command / request, e.g., synchronization reconfiguration) instead of the conditional reconfiguration (e.g., CHO configuration) procedure;

[0125] o only after accessing the target cell, the WD performs the conditional reconfiguration (e.g., CHO configuration) according to the configuration (e.g., RRC reconfiguration) provided in the received message and starts actions upon conditional reconfiguration (e.g., evaluating / monitoring the triggering condition and / or performing a conditional handover of the WD to the target candidate cell upon satisfying the triggering condition); and / or

[0126] - in case of failure of performing the mobility procedure (e.g., failure of performing the synchronization reconfiguration):

[0127] o using any of the configured CHO cells as the selected / selected cell in a later re-establishment procedure, either the previously configured CHO target cell (e.g., prepared or determined by a source NN supporting the source cell) or the CHO target candidate cell received in the message (e.g., synchronization reconfiguration message), and performing a handover of the wireless device to the selected cell instead of re-establishment.

[0128] Some embodiments of the present disclosure comprise a method performed by a target network node (also referred to as target gNodeB) for a reconfiguration procedure including conditional reconfigurations (e.g. CHO configuration), the method comprising one or more of the following:

[0129] - receiving from the source network node (e.g. in the handover preparation procedure) the current configuration of the WD (i.e. the configuration used in the source cell) in a handover / synchronization reconfiguration / PSCell change request message that can include measurements performed and reported by the WD e.g. in an inter-node RRM container;

[0130] - determining one or more conditional reconfigurations (e.g. configuring CHO) for this incoming WD; thus, including in the target configuration of the WD the conditional reconfigurations according to the target NN to be provided to the WD by the source NN; this is what is included in the RRC container sent from the target NN to the source NN in the HO preparation procedure;

[0131] o This decision to include the conditional reconfigurations corresponding to the target network node (i.e. prepared by it) can be based on measurements from the WD included in the inter-node message from the source network node in the HO command / request, determined by the target network node, as mentioned above.

[0132] - If the target candidate cells for the conditional reconfigurations (e.g. CHO configuration) to be given to the WD are not within / supported by the same target network node (e.g. target candidate cells in / supported by other neighbor network nodes), the target network node initiates and supports the conditional reconfiguration preparation procedure of the NNs of the target candidate cells (which can be a HO preparation procedure with the indication that this is for CHO) by sending e.g. target WD configuration (i.e. the WD configuration to be used in the target cells after the WD accesses it). For this purpose, the target network node (e.g. target gNodeB) can create the complete configuration of the WD based on the current configuration of the WD in the source cell and what the target network node wants to modify, thus supporting each NN of the target candidate cells to understand which reconfiguration is requested to be prepared for these conditional reconfigurations.

[0133] - In another alternative, only the complete configuration is allowed to be prepared by the NNs supporting the target candidate cells in the HO.

[0134] - sending to the source network node (e.g., in a handover preparation procedure acknowledgement (ACK) message) a configuration of the WD to use in the target cell after handover execution (e.g., a container with RRCReconfiguration containing a synchronization reconfiguration and a conditional reconfiguration), which includes the conditional reconfiguration. Each conditional reconfiguration is per target candidate cell and can include a trigger condition configuration (which can be one or more measurement identities associated with a measurement configuration) and a configuration associated with the target candidate cell (which can be an RRCReconfiguration, either a full configuration or an incremental configuration, as a baseline with a target configuration of the WD to use after accessing the target cell).

[0135] - receiving from the incoming WD (where the WD uses the configuration associated with the target candidate cell) an RRCReconfigurationComplete message and understanding that the incoming WD is performing an action according to the provided conditional reconfiguration, e.g., monitoring the configured trigger condition.

[0136] Some embodiments advantageously provide that by adding a conditional reconfiguration (e.g., CHO configuration) in the RRCReconfiguration including the HO command to a given target cell (i.e., also including a synchronization reconfiguration / HO command / PSCell change command in the RRCReconfiguration), the amount of signaling for configuring CHO can be reduced, e.g., in cases where the target cell for the incoming WD is capable of conditional reconfiguration (e.g., CHO) and wants to configure CHO for its WD. In addition to the signaling benefit, some embodiments also reduce the delay in making the conditional reconfiguration available to the WD, which can reduce the chance of mobility failure.

[0137] If both configurations (i.e., the conditional reconfiguration associated with the target cell / target network node and the RRCReconfiguration associated with the mobility procedure from source to target cell) are signaled in the same message, e.g., RRCReconfiguration message, some embodiments can also resolve ambiguity. For example, in some embodiments, when including both configurations, the WD can realize that RRCReconfiguration The message is a HO command, which includes a conditional (e.g., CHO) reconfiguration prepared by the target network node, i.e., the WD can access the target cell and then operate according to the conditional reconfiguration (e.g., configured CHO), instead of another way which can create problems in cases where, for example, the WD first applies the CHO configuration and has available measurements, triggering CHO execution, which becomes unclear which HO the WD executes.

[0138] In some embodiments, there can be an explicit indication so that the WD does not start applying the conditional reconfiguration (i.e. start monitoring the conditions) upon reception of the RRCReconfiguration message, but only upon accessing the target cell indicated in the RRCReconfiguration message. In some embodiments, this behavior can be pre-defined in e.g. standard documentation.

[0139] Another benefit of some embodiments can be the fact that the method applies regardless of whether the source network node is capable of conditional reconfiguration or not. In other words, the WD can be capable of conditional reconfiguration, the target network node can be capable of conditional reconfiguration, and the WD is configured with a conditional reconfiguration already upon the HO. In some embodiments, this can be transparent to the source NN. Alternatively, if the WD has a conditional reconfiguration in the source cell, incremental signaling for the conditional reconfiguration from the target NN to the source NN can be supported to further reduce the conditional reconfiguration.

[0140] Another benefit of some embodiments is that in case of a mobility procedure (e.g. handover (synchronous reconfiguration)) failure, the WD has more cells to choose from in a subsequent reconfiguration procedure and can perform a handover instead of re-establishment. There can be an explicit indication whether the WD is allowed to use only target cells received from the source, only target cells received from the target, or both.

[0141] Before describing in detail the exemplary embodiments, notice that the embodiments reside primarily in combinations of apparatus components and processing steps related to conditional handover in handover commands. As such, the conventional

[0142] As used herein, relational terms such as“first” and“second,”“top” and “bottom,” and the like can be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms“a,”“an” and“the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms“comprises,”“comprising,”“includes” and / or“including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0143] In embodiments described herein, the joining term“in communication with” and the like can be used to indicate electrical or data communication, which can be accomplished by, for example, physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling. Persons skilled in the art will understand that multiple components can interoperate and modifications and variations are possible for implementing electrical and data communication.

[0144] In some embodiments described herein, the terms“coupled,”“connected,” and“in communication with” and the like, can be used herein to indicate a connection, although not necessarily directly, and can include wired and / or wireless connection.

[0145] The term“network node” used herein can be any kind of network node included in a radio network, which can further include any base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g-NodeB (gNB), evolved Node B (eNB or eNodeB), Node B, multi-standard radio (MSR) radio node such as MSR BS, multi-cell / multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, remote radio unit (RRU) remote radio head (RRH), core network nodes (e.g., mobile management entity (MME), self-organizing network (SON) node, coordinating node, positioning node, MDT node, etc.), external nodes (e.g., third party nodes, nodes external to the present network), nodes in distributed antenna system (DAS), spectrum access system (SAS) node, element management system (EMS), etc. A network node can also include test equipment. The term“radio node” used herein can also be used to denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

[0146] In some embodiments, the non-limiting terms wireless device (WD) or user equipment (UE) are used interchangeably. A WD here can be any type of wireless device capable of communicating with a network node or another WD over radio signals, such as a wireless device (WD). The WD can also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and / or low-complexity WD, sensor equipped WD, tablet, mobile terminal, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongle, customer premises equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device, etc.

[0147] Also in some embodiments, the general term“radio network node” is used. It can be any kind of radio network node, which can include any of a base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, multi-cell / multicast coordination entity (MCE), IAB node, relay node, access point, radio access point, remote radio unit (RRU) remote radio head (RRH).

[0148] In some embodiments, the terms “conditional reconfiguration”, “CHO configuration”, “conditional handover related configuration”, “configuration for conditional handover”, “conditional synchronization reconfiguration”, “RRC connection reconfiguration with mobility control information”, “conditional reconfiguration”, and “conditional RRC reconfiguration” can be used interchangeably.

[0149] In some embodiments, the terms “node”, “network node”, and “cell” can be used interchangeably and can be used to indicate a network node providing one or more cells and / or a cell provided by such node / network node (e.g., a source cell, a target cell, a candidate cell, etc.).

[0150] Similarly, in some embodiments, the terms “source” or “target” or “candidate” can be used and can be a short form of the terms “source node / cell”, “target network node / cell”, or “candidate node / cell”, respectively.

[0151] In some embodiments, the terms “target node” and “target network node” can be used interchangeably.

[0152] In some embodiments, the term “target cell” can be considered as a cell which is a target of a handover command / request and can be supported by a target network node. In some embodiments, the term “target candidate cell” can be considered as a cell which is a candidate for a conditional reconfiguration determined and / or obtained by a target network node, e.g., in a handover preparation procedure from a source cell to a target cell.

[0153] A cell can generally be a communication cell of a cellular or mobile communication network provided by a node; a serving cell can be a cell on or via which a network node (the node providing or associated with the cell, e.g., a base station or eNodeB or gNB) transmits and / or can transmit data (which can be data other than broadcast data), in particular control and / or user or payload data, to a user equipment and / or a user equipment transmits and / or can transmit data to the node via or on; a serving cell can be a cell for or on which a user equipment is configured and / or it is synchronized to and / or has performed an access procedure, e.g., a random access procedure, and / or it is related to in case the node and / or the user equipment and / or the network follows a standard, e.g., an NR and / or LTE standard, in an RRC_connected or RRC_idle state. One or more carriers (e.g., uplink and / or downlink carriers and / or carriers for both uplink and downlink) can be associated with a cell.

[0154] It can be considered to provide for cellular communication, e.g. via and / or defining a cell which can be provided by a network node, in particular a base station or eNodeB or gNB, at least one uplink (UL) connection and / or channel and / or carrier and at least one downlink (DL) connection and / or channel and / or carrier. The uplink direction can refer to a data transfer direction from a terminal to a network node, e.g. a base station and / or a relay station. The downlink direction can refer to a data transfer direction from a network node, e.g. a base station and / or a relay node, to a terminal. UL and DL can be associated with different frequency resources, e.g. carriers and / or spectrum bands. A cell can comprise at least one uplink carrier and at least one downlink carrier, which can have different frequency bands. A network node, e.g. a base station or eNodeB or gNB, can be adapted to provide and / or define and / or control one or more cells, e.g. a PCell and / or a LA cell.

[0155] Any two or more embodiments described in this disclosure can be combined in any way.

[0156] The term “signaling” as used herein can include any of the following: higher layer signaling (e.g., via radio resource control (RRC) or similar), lower layer signaling (e.g., via a physical control channel or broadcast channel), or a combination thereof. The signaling can be implicit or explicit. The signaling can also be unicast, multicast, or broadcast. The signaling can also be directly to another node or via a third node.

[0157] The term “radio measurement” (also referred to as measurement) as used herein can refer to any measurement performed on a radio signal. The radio measurement can be absolute or relative. The radio measurement can be referred to as a signal level, which can be a signal quality and / or a signal strength. The radio measurement can be, for example, an intra-frequency, inter-frequency, inter-RAT measurement, CA measurement, etc. The radio measurement can be one-way (e.g. DL or UL) or two-way (e.g. round trip time (RTT), receive-transmit (Rx-Tx), etc.). Some examples of radio measurements: timing measurements (e.g. time of arrival (TOA), timing advance, RTT, reference signal time difference (RSTD), Rx-Tx, propagation delay, etc.), angle measurements (e.g. angle of arrival), power-based measurements (e.g. received signal power, reference signal received power (RSRP), received signal quality, reference signal quality (RSRQ), signal to interference plus noise ratio (SINR), signal to noise ratio (SNR), interference power, total interference plus noise, received signal strength indication (RSSI), noise power, etc.), cell detection or cell identification, radio link monitoring (RLM), system information (SI) reading, etc. The WD performs inter-frequency and inter-RAT measurements in measurement gaps, unless the WD is able to do such measurements without gaps. Examples of measurement gaps are measurement gap id #0 (every 6 ms of every 40 ms), measurement gap id #1 (every 6 ms of every 80 ms), etc. The measurement gaps are configured at the WD by the network node.

[0158] In some embodiments, the information about the one or more resources can be considered to be sent in a message having a particular format. The message can comprise or represent bits representing payload information and coded bits (e.g. for error coding).

[0159] Receiving (or obtaining) the information can comprise receiving one or more information messages (e.g. RRC reconfiguration). Receiving the control signaling can be considered to comprise demodulating and / or decoding and / or detecting (e.g. blind detection) one or more messages, in particular messages carried by the signaling, e.g. based on a hypothesized resource set (which can be searched and / or listened to for the information). It can be assumed that both sides of the communication are aware of the configuration, and the resource set can be determined, e.g. based on a reference size.

[0160] Signaling can generally comprise one or more symbols and / or signals and / or messages. A signal can comprise one or more bits. An indication can represent signaling, and / or can be implemented as one signal or multiple signals. One or more signals can be comprised in and / or represented by a message. Signaling, in particular control signaling, can comprise multiple signals and / or messages, which can be transmitted on different carriers and / or associated with different signaling procedures, e.g. representing and / or relating to one or more such procedures and / or corresponding information. An indication can comprise and / or be comprised in signaling and / or multiple signals and / or messages, which can be transmitted on different carriers and / or associated with different confirmation signaling procedures, e.g. representing and / or relating to one or more such procedures. Signaling associated with a channel can be transmitted such that signaling and / or information representing the channel, and / or the signaling is interpreted by a transmitter and / or receiver as belonging to the channel. Such signaling can generally conform to transmission parameters and / or formats for the channel.

[0161] An indication can generally explicitly and / or implicitly indicate the information it represents and / or indicates. Implicit indication can e.g. be based on a location and / or resource used for transmission. Explicit indication can e.g. be based on parameterization with one or more parameters, and / or one or more indices corresponding to a table, and / or one or more bit patterns representing the information.

[0162] Configuring a radio node

[0163] Configuring a radio node, in particular a terminal or user equipment or WD, can refer to adapting or causing or setting or instructing the radio node to operate in accordance with the configuration. The configuration can be done by another device, e.g. a network node, e.g. a radio node of a network such as a base station or eNodeB, or the network, in which case it can comprise transmitting configuration data to the radio node to be configured. Such configuration data can represent the configuration to be configured and / or comprise one or more instructions relating to the configuration, e.g. a configuration for transmitting and / or receiving on allocated resources, in particular frequency resources, or, e.g., a configuration for performing a specific measurement on a specific subframe or radio resource. The radio node can configure itself, e.g. based on configuration data received from the network or network node. The network node can utilize and / or be adapted to utilize its circuitry for configuring. Allocation information can be considered a form of configuration data. Configuration data can comprise and / or be represented by configuration information and / or one or more corresponding indications and / or messages.

[0164] General configuration

[0165] Generally, configuring can comprise determining configuration data representing the configuration and providing (e.g., transmitting) it to one or more other nodes (in parallel and / or sequentially), which can further transmit it to the radio node (or another node, which can be repeated until it reaches the wireless device). Alternatively or additionally, configuring the radio node, e.g., via a network node or other device, can comprise receiving configuration data and / or data relating to configuration data, e.g., from another node such as a network node (which can be a higher layer node of the network), and / or transmitting the received configuration data to the radio node. Thus, determining the configuration and transmitting the configuration data to the radio node can be performed by different network nodes or entities, which can be able to communicate via appropriate interfaces, e.g., an X2 interface or a corresponding interface for NR in case of LTE. Configuring a terminal (e.g., WD) can comprise scheduling downlink and / or uplink transmissions for the terminal (e.g., downlink data and / or downlink control signaling and / or DCI and / or uplink control or data or communication signaling, in particular acknowledgement signaling) and / or configuring resources and / or resource pools for it. In particular, configuring a terminal (e.g., WD) can comprise configuring the WD to perform certain measurements on certain subframes or radio resources according to embodiments of the disclosure, and reporting such measurements.

[0166] It is noted that while terms from one particular wireless system, such as, for example, 3GPP LTE and / or New Radio (NR), can be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including but not limited to Wideband Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), can also benefit from exploiting ideas covered within this disclosure.

[0167] It is further noted that functions described herein as being performed by a wireless device or a network node can be distributed in a number of wireless devices and / or network nodes. In other words, it is contemplated that functions of the network nodes and wireless devices described herein can be performed by a plurality of physical devices working in concert. It is further noted that functions described herein as being performed by a network node can be performed by a plurality of network nodes.

[0168] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0169] Some embodiments provide arrangements for conditional handover in handover commands.

[0170] Reference is made again to the drawings, wherein like reference numerals are used to denote identical elements throughout the various figures, Figure 4 A schematic diagram of a communication system 10 according to an embodiment is shown in Figure 1 and can for example represent a 3GPP-type cellular network that can support standards such as LTE and / or NR (5G), and includes access network 12, such as a radio access network, and core network 14. Access network 12 comprises a plurality of network nodes 16a, 16b, 16c (collectively referred to as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (collectively referred to as coverage areas 18). Each network node 16a, 16b, 16c is connectable to core network 14 over a wired or wireless connection 20. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices 22) are illustrated in this example, the

[0171] Furthermore, it is contemplated that a WD 22 can be in communication with more than one network node 16 and more than one type of network node 16 at the same time and / or be configured to individually communicate with more than one network node 16 and more than one type of network node 16. For example, a WD 22 can have dual connectivity with an LTE-enabled network node 16 and an NR-enabled network node 16, which can be the same or a different type of network node 16. As an example, WD 22 can be in 5G / NR mmWave communication with an eNB of an LTE / LTE-A network and with a gNB of a 5G / NR network.

[0172] Communication system 10 can be in communication with a host computer 24, which can embody a stand-alone server, a cloud-implemented server, distributed servers, or a combination thereof, or as processing resources in a server farm. Host computer 24 can be owned or controlled by a service provider or be operated on behalf of the service provider. Connections 26, 28 between communication system 10 and host computer 24 can extend directly from core network 14 to host computer 24 or can extend via an optional intermediate network 30. Intermediate network 30 can be a combination of one or more of the following: a public, private, or hosted network; an Internet Protocol (IP) network; a local area network (LAN); a metropolitan area network (MAN); and a wide area network (WAN). Intermediate network 30 can include a public network, a private network, or a combination of both. Intermediate network 30 can include the Internet. In some embodiments, intermediate network 30 can include two or more sub-networks.

[0173] Figure 4The communication system as a whole enables connectivity between the connected WDs 22a, 22b and the host computer 24. The connectivity can be described as an Over-the-Top (OTT) connection. The host computer 24 and the connected WDs 22a, 22b are configured to communicate data and / or signaling via the OTT connection using the access network 12, the core network 14, any intermediate network 30 and possible further infrastructure (not shown) as intermediaries. The OTT connection can be transparent in the sense that at least some of the participating devices - e.g. the network nodes 16 - do not know or are not aware of the source and / or the destination of the data packets and / or signaling messages they are relaying. For example, the network nodes 16 can not know that an incoming downlink communication has originated from the host computer 24 or that an outgoing uplink communication is destined to the host computer 24. The network nodes 16 can also not know that an incoming downlink communication has been previously transmitted by the WD 22a or that an outgoing uplink communication has been previously received by the WD 22a from.

[0174] The network node 16 is configured to comprise a configuration unit 32 configured to cause the network node 16 to: receive a request to perform a mobility procedure for a wireless device from a source cell supported by a source network node to a target cell supported by the network node, the request comprising a current configuration of the wireless device in the source cell; determine, upon receiving the request, a conditional reconfiguration for the wireless device; and transmit the conditional reconfiguration and a radio resource control (RRC) reconfiguration for the wireless device, the RRC reconfiguration associated with the requested mobility procedure from the source cell to the target cell supported by the network node and the conditional reconfiguration associated with a target candidate cell determined by the network node. In some embodiments, the configuration unit 32 can be configured to cause the network node 16 to perform one or more of the following operations: receive a handover (HO) preparation message from the source network node in a HO procedure, the HO preparation message comprising a current configuration of the WD in the source cell; determine a conditional handover (CHO) configuration for the WD; and transmit a message to the source node, the message comprising the determined CHO configuration.

[0175] The wireless device 22 is configured to comprise a switching unit 34 configured to cause the wireless device 22 to: receive at least one radio resource control (RRC) reconfiguration message, the at least one RRC reconfiguration message comprising a conditional reconfiguration and an indication that the wireless device is to perform a mobility procedure, the indication that the wireless device is to perform a mobility procedure indicating to perform a mobility procedure from a source cell supported by a network node to a target cell supported by a target network node, and the conditional reconfiguration being associated with a target candidate cell corresponding to the target network node. In some embodiments, the switching unit 34 is configured to cause the wireless device 22 to: receive a message, the message being a radio resource control (RRC) reconfiguration message comprising a conditional handover (CHO) configuration and an indication of a handover (HO) command, the CHO being prepared by a target network node, the HO command being prepared by a source network node; in response to the received message, attempt to access the target network node indicated in the HO command; and / or as a result of accessing the target network node, perform a CHO according to the CHO configuration in the received message.

[0176] Example implementations, in accordance with an embodiment, of the WD 22, network node 16 and host computer 24 discussed in the previous paragraphs will now be described. Figure 2 In the communications system 10, the host computer 24 includes hardware 38 that includes a communication interface 40 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communications system 10. The host computer 24 further comprises processing circuitry 42, which can have storage and / or processing capabilities. The processing circuitry 42 can comprise a processor 44 and memory 46. In particular, in addition to or instead of a processor and memory, such as a central processing unit, the processing circuitry 42 can comprise integrated circuitry for

[0177] The processing circuitry 42 can be configured to control any of the methods and / or processes described herein and / or to cause such methods and / or processes to be performed, e.g., by the host computer 24. The processor 44 corresponds to one or more processors 44 for performing the functions of the host computer 24 described herein. The host computer 24 includes memory 46 that is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 48 and / or the host application 50 can include instructions that, when executed by the processor 44 and / or processing circuitry 42, enable the processor 44 and / or processing circuitry 42 to perform the processes described herein with respect to the host computer 24. The instructions can be software associated with the host computer 24.

[0178] The software 48 can be executable by the processing circuitry 42. The software 48 includes a host application 50. The host application 50 can be operable to provide a service to a remote user, such as a WD 22 connecting via OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the remote user, the host application 50 can provide user data which is transmitted using the OTT connection 52. The “user data” can be data and information described herein as implementing the described functionality. In one embodiment, the host computer 24 can be configured for providing control and functionality to a service provider and can be operated by the service provider or on behalf of the service provider. The processing circuitry 42 of the host computer 24 can enable the host computer 24 to observe, monitor, control, send to, and / or receive from the network node 16 and / or the wireless device 22. The processing circuitry 42 of the host computer 24 can include a monitoring unit 54 configured to enable the service provider to observe, monitor, control, send to, and / or receive from the network node 16 and / or the wireless device 22.

[0179] The communication system 10 further includes the network node 16 providing a

[0180] In the illustrated embodiment, the hardware 58 of the network node 16 further includes processing circuitry 68. The processing circuitry 68 can include a processor 70 and a memory 72. In particular, in addition to or instead of a processor such as a central processing unit(s) and a memory, the processing circuitry 68 can comprise integrated circuitry configured to process and / or control the

[0181] Thus, the network node 16 also has software 74 stored internally in, for example, memory 72 or stored external to the network node 16 and accessible by the network node 16 by way of an external connection (e.g., a database, a memory array, a network storage device, or the like). The software 74 can be executable by the processing circuitry 68. The processing circuitry 68 can be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, for example, by the network node 16. The processor 70 corresponds to one or more processors 70 for performing network node 16 functions described herein. The memory 72 is configured to store data, programmatic software code, and / or other information used by the network node 16 described herein. In some embodiments, the software 74 can include instructions that, when executed by the processor 70 and / or processing circuitry 68, cause the processor 70 and / or processing circuitry 68 to perform the processes described herein with respect to the network node 16. For example, the processing circuitry 68 of the network node 16 can include a configuration unit 32 configured to perform the network node methods discussed herein, e.g., with reference to the methods discussed in relation to Figure 10 and other figures.

[0182] The communication system 10 also includes the WD 22 already referred to. The WD 22 can have hardware 80, which can include a radio interface 82 configured to set up and maintain a wireless connection 64 with a network node 16 serving a coverage area in which the WD 22 is currently located. The radio interface 82 can be formed as or can include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers.

[0183] The hardware 80 of WD 22 further includes processing circuitry 84. The processing circuitry 84 can include a processor 86 and memory 88. In particular, in addition to or instead of a processor and memory, the processing circuitry 84 can comprise integrated circuitry for processing and / or control, such as one or more processors and / or processor cores and / or FPGAs (Field Programmable Gate Array) and / or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions.

[0184] Thus, the WD 22 can further comprise software 90, which is stored in, for example, memory 88 at the WD 22, or in an external memory accessible by the WD 22 (e.g., a database, a storage array, a network storage device, etc.). The software 90 can be executable by the processing circuitry 84. The software 90 can include a client application 92. The client application 92 can be operable to provide a service to a human or non-human user via the WD 22, with support from the host computer 24. In the host computer 24, an executing host application 50 can communicate with the executing client application 92 via the OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the user, the client application 92 can receive request data from the host application 50 and provide user data in response to the request data. The OTT connection 52 can transfer both the request data and the user data. The client application 92 can interact with the user to generate the user data that it provides.

[0185] The processing circuitry 84 can be configured to control any of the methods and / or processes described herein and / or to cause such methods, and / or processes to be performed, e.g., by the WD 22. The processor 86 corresponds to one or more processors 86 for performing WD 22 functions described herein. The WD 22 includes memory 88 that is configured to store data, programmatic software code and / or other information described herein. In some embodiments, the software 90 and / or the host application 92 can include instructions that, when executed by the processor 86 and / or processing circuitry 84, cause the processor 86 and / or processing circuitry 84 to perform the processes described herein with respect to the WD 22. For example, the processing circuitry 84 of the wireless device 22 can include a switching unit 34 configured to perform the WD methods discussed herein, e.g., with respect to the methods discussed with reference to Figure 11 and other drawings.

[0186] In some embodiments, the inner workings of the network node 16, WD 22, and host computer 24 can be as shown in and described in connection with Figure 1.Figure 5 The surrounding network topology can be Figure 4 of the network topology.

[0187] In Figure 5 The OTT connection 52 has been drawn abstractly to show the passage of messages between the host computer 24 and wireless device 22 via the network nodes 16 without any reference to any intermediary devices and the precise routing of messages via these devices. The network infrastructure can determine the routing, which it can be configured to hide from the WD 22 or from the service provider operating the host computer 24, or both. While the OTT connection 52 is active, the network infrastructure can further take decisions that it dynamically changes the routing (e.g., based on load balancing consideration or reconfiguration of the network).

[0188] The wireless connection 64 between the WD 22 and the network nodes 16 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the WD 22 using the OTT connection 52 in which the wireless connection 64 forms the last segment. More precisely, the teachings of these embodiments can improve the data rate, latency, and / or power consumption, thereby providing benefits such as reduced user waiting time, relaxed restrictions on file size, better responsiveness, extended battery lifetime, etc.

[0189] In some embodiments, a measurement procedure can be provided for the purpose of monitoring the data rate, latency, and other factors on which one or more of the embodiments improve. There can further be an optional network functionality for reconfiguring the OTT connection 52 between the host computer 24 and the WD 22, in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection 52 can be implemented in the software 48 of the host computer 24 or in the software 90 of the WD 22, or both. In embodiments, sensors (not shown) can be deployed in or in association with the communication devices through which the OTT connection 52 passes; the sensors can participate in the measurement procedure by providing values of the monitored quantities exemplified above, or physical quantities from which the software 48, 90 can compute or estimate the monitored quantities. The reconfiguring of the OTT connection 52 can include message format, retransmission settings, preferred routing etc.; the reconfiguring need not necessarily affect the network nodes 16, and it can be unknown or imperceptible to the network nodes 16. Such procedures and functionalities are known in the art and practiced in the art. In certain embodiments, the measurement can involve proprietary WD signaling facilitating the host computer’s 24 measurements of throughput, propagation times, latency and the like. In some embodiments, the measurement can be implemented in a way that is transparent to the WD 22, e.g. by offloading the WD 22 to use specific network resources for the purpose of the measurement.

[0190] Thus, in some embodiments, the host computer 24 includes processing circuitry 42 configured to provide user data and a communication interface 40 configured to forward the user data to a cellular network for transmission to the WD 22. In some embodiments, the cellular network further includes the network node 16 with a radio interface 62. In some embodiments, the network node 16 is configured to, and / or the network node’s 16 processing circuitry 68 is configured to perform the functions and / or methods described herein for preparing / initiating / maintaining / supporting / ending transmissions to the WD 22, and / or preparing / terminating / maintaining / supporting / ending reception of transmissions from the WD 22.

[0191] In some embodiments, the host computer 24 includes processing circuitry 42 and a communication interface 40 configured to receive user data that originated from a transmission from the WD 22 to the network node 16. In some embodiments, the WD 22 is configured to perform the functions and / or methods described herein for preparing / initiating / maintaining / supporting / ending transmissions to the network node 16, and / or preparing / terminating / maintaining / supporting / ending reception of transmissions from the network node 16, and / or includes radio interface 82 and / or processing circuitry 84 configured to perform the functions and / or methods described herein for preparing / initiating / maintaining / supporting / ending transmissions to the network node 16, and / or preparing / terminating / maintaining / supporting / ending reception of transmissions from the network node 16.

[0192] Although Figure 4 and 5 Various “units” such as the configuration unit 32 and the switching unit 34 are shown within the respective processors, but it is contemplated that these units can be implemented such that parts of the units are stored in the corresponding memory in the processing circuitry. In other words, these units can be implemented in hardware or a combination of hardware and software within the processing circuitry.

[0193] Figure 6 is a flowchart illustrating an exemplary method implemented in a communication system including a host computer, a network node and a WD, in accordance with one embodiment. The communication system can implement a radio access technology such as, for example, LTE or 5G / NR. Figure 4 and 5 is a flowchart illustrating an exemplary method implemented in a communication system including a host computer, a network node and a WD, in accordance with one embodiment. The communication system can implement a radio access technology such as, for example, LTE or 5G / NR. Figure 5Those described with reference to the example of Fig. 2. In a first step of the method, the host computer 24 provides user data (Block S100). In an optional substep of the first step, the host computer 24 provides the user data by executing a host application, such as e.g. the host application 50 (Block S102). In a second step, the host computer 24 initiates a transmission of the user data to the WD 22 (Block S104). In an optional third step, the network node 16 transmits to the WD 22 the user data carried in the transmission initiated by the host computer 24, according to the teachings of the embodiments described throughout this disclosure (Block S106). In an optional fourth step, the WD 22 executes a client application, such as e.g. a client application associated with the host application 50 executed by the host computer 24 (e.g., the client application 92) (Block S108).

[0194] Figure 7 is a flow chart illustrating an exemplary method implemented in a communication system such as, for example, the Figure 4 communication system of Fig. 2, in accordance with one embodiment. The communication system includes a host computer 24, a network node 16 and a WD 22, which can be those described Figure 4 and Figure 5 with reference to Figs. 1 and 2. In a first step of the method, the host computer 24 provides user data (Block S110). In an optional substep (not shown), the host computer 24 provides the user data by executing a host application, such as e.g. the host application 50. In a second step, the host computer 24 initiates a transmission of the user data to the WD 22 (Block S112). The transmission can pass via the network node 16, according to the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD 22 receives the user data carried in the transmission (Block S114).

[0195] Figure 8 is a flow chart illustrating an exemplary method implemented in a communication system such as, for example, the Figure 4 communication system of Fig. 2, in accordance with one embodiment. The communication system includes a host computer 24, a network node 16 and a WD 22, which can be those described Figure 4 and Figure 5The ones described with reference to the preceding figures. In an optional first step of the method, the WD 22 receives input provided by the host computer 24 (Block S116). In an optional substep of the first step, the WD 22 executes the client application 92, which provides the user data in reaction to the received input provided by the host computer 24 (Block S118). Additionally or alternatively, in an optional second step, the WD 22 provides user data (Block S120). In an optional substep of the second step, the WD provides the user data by executing a client application, such as, for example, the client application 92 (Block S122). In providing the user data, the executed client application 92 can further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the WD 22 can, in an optional third substep, initiate transmission of the user data to the host computer 24 (Block S124). In a fourth step of the method, the host computer 24 receives the user data transmitted from the WD 22, according to the teachings of the embodiments described throughout this disclosure (Block S126).

[0196] Figure 9 is a flow chart illustrating an exemplary method implemented in a communication system Figure 4 such as, for example, the one shown in Fig. 1, in accordance with one embodiment. The communication system includes a host computer 24, a network node 16, and a WD 22, which can be those described Figure 4 and Figure 5 with reference to the preceding figures. In an optional first step of the method, the network node 16 receives user data from the WD 22, according to the teachings of the embodiments described throughout this disclosure (Block S128). In an optional second step, the network node 16 initiates a transmission of the received user data to the host computer 24 (Block S130). In a third step, the host computer 24 receives the user data carried in the transmission initiated by the network node 16 (Block S132).

[0197] Figure 10is a flowchart of an exemplary procedure in a network node 16 for conditional handover in a handover command according to some embodiments of the present disclosure. One or more blocks and / or functions and / or methods performed by the network node 16 according to the example method can be performed by one or more elements of the network node 16, e.g., via the configuration unit 32, processor 70, communication interface 60, radio interface 62, etc., in the processing circuitry 68. The example method includes receiving (block S134), e.g., via the configuration unit 32, processing circuitry 68, processor 70, communication interface 60, and / or radio interface 62, a request to perform a mobility procedure for a wireless device from a source cell supported by a source network node to a target cell supported by the network node, the request including a current configuration for the wireless device in the source cell. The method includes determining (block S136), e.g., via the configuration unit 32, processing circuitry 68, processor 70, communication interface 60, and / or radio interface 62, a conditional reconfiguration for the wireless device upon receiving the request. The method includes sending (block S138), e.g., via the configuration unit 32, processing circuitry 68, processor 70, communication interface 60, and / or radio interface 62, the conditional reconfiguration and a radio resource control (RRC) reconfiguration for the wireless device, the RRC reconfiguration being associated with the requested mobility procedure from the source cell to the target cell supported by the network node and the conditional reconfiguration being associated with a target candidate cell determined by the network node.

[0198] In some embodiments, the wireless device is to use the conditional reconfiguration upon accessing the target cell indicated in the requested mobility procedure. In some embodiments, the target candidate cell associated with the conditional reconfiguration is selectable by the wireless device for handover of the wireless device to the target candidate cell upon failure of accessing the target cell indicated in the requested mobility procedure. In some embodiments, the target candidate cell associated with the conditional reconfiguration is not selectable by the wireless device for handover of the wireless device to the target candidate cell upon failure of accessing the target cell indicated in the requested mobility procedure.

[0199] In some embodiments, the mobility procedure is a handover of the wireless device from a source cell to a target cell. In some embodiments, the mobility procedure corresponds to requesting at least one of an addition and a change of a primary secondary cell (PSCell) for the wireless device. In some embodiments, determining to prepare a conditional reconfiguration for the wireless device is based at least in part on measurements from the wireless device included in the received request to perform the mobility procedure. In some embodiments, preparing the conditional reconfiguration for the wireless device includes transmitting, such as via configuration unit 32, processing circuitry 68, processor 70, communication interface 60, and / or radio interface 62, an RRC reconfiguration for the wireless device to a target candidate network node supporting a target candidate cell. The method includes obtaining, such as via configuration unit 32, processing circuitry 68, processor 70, communication interface 60, and / or radio interface 62, from the target candidate network node, a conditional reconfiguration based at least in part on the transmitted RRC reconfiguration.

[0200] In some embodiments, at least one of the conditional reconfiguration associated with the target candidate cell and the RRC reconfiguration associated with the target cell of the mobility procedure is based at least in part on a received current configuration for the wireless device in the source cell. In some embodiments, the method further includes receiving, such as via configuration unit 32, processing circuitry 68, processor 70, communication interface 60, and / or radio interface 62, an RRC reconfiguration complete message; and as a result of the received RRC reconfiguration complete message, communicating, such as via radio interface 62, with the wireless device based on an assumption that the wireless device is operating according to the conditional reconfiguration.

[0201] In some embodiments, the method includes receiving, such as via configuration unit 32, processing circuitry 68, processor 70, and / or radio interface 62, a handover (HO) preparation message from a source network node in a HO procedure, the HO preparation message including a current configuration of a WD in a source cell. The method includes determining, such as via configuration unit 32, processing circuitry 68, processor 70, and / or radio interface 62, a conditional handover (CHO) configuration for the WD. The method includes transmitting, such as via configuration unit 32, processing circuitry 68, processor 70, and / or radio interface 62, a message to the source node, the message including the determined CHO configuration. In some embodiments, the method includes receiving a radio resource control (RRC) reconfiguration complete message from the WD 22; and / or as a result of the received RRC reconfiguration complete message, communicating with the WD 22 based on an assumption that the WD 22 is operating according to the CHO configuration.

[0202] Figure 11is a flowchart of an exemplary procedure in a wireless device 22 for conditional handover in a handover command according to some embodiments of the present disclosure. One or more blocks and / or functions and / or methods performed by the WD 22 can be performed by one or more elements of the WD 22, e.g., by the HO unit 34, the processor 86, the radio interface 82, etc., in the processing circuitry 84. The example method includes, e.g., receiving (block S140), via the HO unit 34, the processing circuitry 84, the processor 86, and / or the radio interface 82, at least one radio resource control (RRC) reconfiguration message, the at least one RRC reconfiguration message including a conditional reconfiguration and an indication that the wireless device is to perform a mobility procedure. The indication to perform the mobility procedure indicates to perform a mobility procedure from a source cell supported by a network node to a target cell supported by a target network node. The conditional reconfiguration is associated with a target candidate cell corresponding to the target network node.

[0203] In some embodiments, the method further includes, upon receiving the at least one RRC reconfiguration message, performing the mobility procedure indicated in the received at least one RRC reconfiguration by attempting to access the target cell, e.g., via the HO unit 34, the processing circuitry 84, the processor 86, and / or the radio interface 82. In some embodiments, the method includes, as a result of accessing the target cell, performing at least one action in accordance with the conditional reconfiguration included in the received at least one RRC reconfiguration, e.g., via the HO unit 34, the processing circuitry 84, the processor 86, and / or the radio interface 82. In some embodiments, the method further includes, as a result of the attempt to access the target cell failing, selecting a candidate cell associated with the conditional handover and performing a handover of the wireless device to the selected candidate cell.

[0204] In some embodiments, selecting the candidate cell associated with the conditional handover includes, as a result of the attempt to access the target cell failing, selecting the candidate cell from among at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and the target network node, e.g., via the HO unit 34, the processing circuitry 84, the processor 86, and / or the radio interface 82. In some embodiments, selecting the candidate cell associated with the conditional handover includes, as a result of the attempt to access the target cell failing, selecting the candidate cell from among at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and a network node supporting the source cell, e.g., via the HO unit 34, the processing circuitry 84, the processor 86, and / or the radio interface 82.

[0205] In some embodiments, the explicit indication indicates to the wireless device to select the candidate cell from at least one of a first plurality of candidate cells associated with a network node supporting the source cell and a second plurality of candidate cells associated with the target network node as a result of a failure to attempt access to the target cell. In some embodiments, the indication to conditionally reconfigure and perform the mobility procedure are both included in the same RRC reconfiguration message. In some embodiments, the explicit indication indicates to the wireless device to perform the conditional reconfiguration included in the same RRC reconfiguration message only after accessing the target cell according to the mobility procedure indicated in the same RRC reconfiguration message.

[0206] In some embodiments, the indication to conditionally reconfigure and perform the mobility procedure are in the same RRC reconfiguration message. In some embodiments, the method further comprises performing, e.g., via the HO unit 34, processing circuitry 84, processor 86, and / or radio interface 82, an RRC reestablishment procedure instead of the indicated mobility procedure and the conditional reconfiguration when the indication to conditionally reconfigure and perform the mobility procedure are both included in the same RRC reconfiguration message. In some embodiments, the mobility procedure is a handover of the wireless device from the source cell to the target cell. In some embodiments, the mobility procedure corresponds to a request to add and change at least one of a primary secondary cell, PSCell, to the wireless device. In some embodiments, the indication to perform the mobility procedure comprises one of a synchronization reconfiguration field and a mobility control information field included in the at least one RRC reconfiguration message.

[0207] In some embodiments, the method further comprises receiving, e.g., via the HO unit 34, processing circuitry 84, processor 86, and / or radio interface 82, signaling indicating one of the conditional reconfiguration of the target candidate cell prepared by the target network node to be added, modified, and released. In some embodiments, the conditional reconfiguration associated with the target candidate cell comprises a trigger condition configuration comprising a set of pointers pointing to at least one measurement identifier, and each measurement identifier of the at least one measurement identifier is associated with at least one trigger condition and an RRC reconfiguration. In some embodiments, the method further comprises determining, e.g., via the HO unit 34, processing circuitry 84, processor 86, and / or radio interface 82, not to send an RRC reconfiguration complete message based at least in part on a presence of the conditional reconfiguration associated with the target candidate cell in the at least one RRC reconfiguration message.

[0208] In some embodiments, the method includes receiving, e.g., via HO unit 34, processing circuitry 84, processor 86, and / or radio interface 82, a message. The message can be a radio resource control (RRC) reconfiguration message including a conditional handover (CHO) configuration and an indication of a handover (HO) command, the CHO prepared by a target network node and the HO command prepared by a source network node. The method includes attempting, e.g., via HO unit 34, processing circuitry 84, processor 86, and / or radio interface 82, to access the target network node indicated in the HO command in response to the received message. The method includes performing, e.g., via HO unit 34, processing circuitry 84, processor 86, and / or radio interface 82, a CHO according to the CHO configuration in the received message as a result of accessing the target network node. In some embodiments, the method includes selecting a candidate cell indicated in the CHO configuration and performing a handover of the WD to the selected candidate cell in response to a failure of the attempt to access the target network node.

[0209] Having described the general process flow of the arrangements of the present disclosure and provided examples of hardware and software arrangements for implementing the processes and functions of the present disclosure, the following sections provide details and examples of arrangements for conditional handover in handover commands, which can be implemented by network node 16, wireless device 22, and / or host computer 24.

[0210] Introduction

[0211] In some embodiments, a set of conditional reconfigurations (e.g., RRCReconfiguration(s)) are configured, e.g., as a configuration via CHO, which the WD 22 can perform a handover (or conditional handover, depending on how the procedure is named in the NR RRC specification) when the conditions for the handover are met. In the context of the present disclosure, the present disclosure can interchangeably refer to conditional reconfigurations, CHO configurations, or conditional handover related configurations, and can be for a cell, a list of cells, a measurement object, or a frequency. In the case of cell association, they can be for the same radio access technology (RAT), or for different RATs.

[0212] In the context of the method, the “conditional handover related configuration”, also referred to as conditional reconfiguration for a cell, can include at least one or more of the following:

[0213] - a message like RRCReconfiguration (or any message with equivalent content and / or purpose) can contain a reconfigurationWithSync IE (using NR terminology defined in 3GPP Technical Specification (TS) 38.311) and be prepared by the target network node 16. Alternatively, using E-UTRA terminology, RRCConnectionReconfiguration (defined in 3GPP Technical Specification (TS) 36.331) with a mobilityControlInfo IE;

[0214] - a trigger condition configuration, e.g. A1-A6 trigger events or B1-B2 inter-RAT trigger events (as defined in the reportConfig IE in 3GPP TS 38.331 / 3GPP TS A 36.331), where instead of triggering a measurement report, a conditional handover is triggered. This can be a pointer to a measurement configuration, e.g. a measurement identifier, or a list of measurement identifiers. Other conditional handover control parameters, e.g. a timer defining the validity of a target candidate resource, etc.

[0215] Throughout the disclosure, the term “handover” or “synchronous reconfiguration” is used herein, e.g. with similar meaning. Thus, a conditional handover can also be referred to as a conditional synchronous reconfiguration. In NR terminology, a handover is typically referred to as RRCReconfiguration with reconfigurationWithSync (containing fields necessary to perform a handover, such as target information, such as frequency, cell identifier, random access configuration, etc.). In E-UTRA terminology, a handover is typically referred to as RRCConnectionReconfiguration with mobilityControlInfo (containing fields necessary to perform a handover). Fundamentally, the disclosure is also applicable to other forms of mobility procedures, e.g. PSCell change, PSCell addition, etc.

[0216] In some embodiments, most of the WD 22 (and network node 16) actions and network node 16 configurations defined in the disclosure are described as being performed in NR or E-UTRA; in other words, conditional reconfiguration for NR cells (e.g. configuration of conditional HO) is received in NR. However, these techniques, methods and / or principles are also applicable when any of these steps occur in a different RAT, e.g.:

[0217] - the WD 22 has NR as source and NR as target; the target candidate associated with the NR target can be a LTE cell or a NR cell;

[0218] - WD 22 has NR as source and LTE as target; target candidates associated with the NR target can be LTE cells or NR cells;

[0219] - WD 22 has LTE as source and LTE as target; target candidates associated with the NR target can be LTE cells or NR cells; and / or

[0220] - WD 22 has LTE as source and NR as target; target candidates associated with the NR target can be LTE cells or NR cells.

[0221] Further example details and example signaling flows of some embodiments

[0222] The present disclosure describes a method performed by a wireless device 22 (also referred to as a user equipment (UE)) for a reconfiguration procedure. In some embodiments, the method comprises:

[0223] - receiving a message (e.g., RRCReconfiguration) comprising:

[0224] o a conditional reconfiguration (e.g., CHO configuration) prepared by a target network node 16 supporting a target cell;

[0225] o an indication that the WD can perform a mobility procedure (e.g., a synchronous reconfiguration indicating a handover of the WD from a source cell to a target cell). The indication can be the presence of a synchronousReconfiguration field within CellGroupConfig;

[0226] The following sections can provide examples of how to modify or specify the RRC specification to provide one or more arrangements proposed in the present disclosure (e.g., a WD 22 receiving the message above).

[0227] RRC reconfiguration (both conditional reconfiguration and synchronous reconfiguration allowed in the same RRC reconfiguration message)

[0228] One example of how it can be implemented in ASN.1 in the RRC specification is shown below, where the possibility to signal both a conditional reconfiguration (e.g., CHO configuration) and a mobility procedure request (e.g., HO command) is considered.

[0229] The RRCReconfiguration message is a command to modify an RRC connection, e.g., to a specific cell (e.g., source cell). It can convey information for measurement configuration, mobility control, radio resource configuration (including resource block (RB), MAC main configuration, and physical channel configuration, etc.), and AS security configuration. It can also convey a conditional reconfiguration in a container with RRCReconfiguration to be applied only upon fulfillment of a trigger condition.

[0230] - Signaling radio bearers: SRB1 or SRB3

[0231] - Radio link control - service access point (RLC-SAP): Acknowledged mode (AM)

[0232] - Logical channel: Dedicated control channel (DCCH)

[0233] - Direction: network node 16 to WD 22 (e.g., UE)

[0234] RRCReconfiguration message

[0235]

[0236]

[0237]

[0238]

[0239]

[0240]

[0241]

[0242] In alternative or additional embodiments, only one of the two fields (e.g. conditional reconfiguration and synchronization reconfiguration) can be included in the same message at a time, e.g. in the RRCReconfiguration. At least compared to the prior art, the benefit in this embodiment is that it avoids WD 22 misbehavior due to ambiguities that can exist when including both configurations without further specification, i.e. including additional conditions to make it clear that CHO cannot be signaled when HO / PSCell change / PSCell addition is signaled to the WD 22, i.e. when masterCellGroupConfig and / or secondaryCellGroupConfig includes a synchronization reconfiguration. In other words, if both fields are included, the WD 22 does not apply the message and considers that it cannot comply with it and performs actions after e.g. re-establishment. An example of such an alternative is shown below:

[0243] RRC Reconfiguration (prohibition of conditional reconfiguration and synchronization reconfiguration in the same RRC Reconfiguration message)

[0244] Below is shown one example of how it can be implemented in ASN.1 in the RRC specification, where the possibility of signaling only one of the following is considered: conditional reconfiguration (e.g. CHO configuration) and mobility procedure request (e.g. HO command).

[0245] The RRCReconfiguration message is a command to modify an RRC connection. It can convey information for measurement configuration, mobility control, radio resource configuration (including resource blocks (RBs), MAC main configuration, and physical channel configuration, etc.), and AS security configuration. It can also convey a conditional reconfiguration using a container with RRCReconfiguration to be applied only after a trigger condition is met.

[0246] - Signaling Radio Bearers: SRB1 or SRB3

[0247] - RLC-SAP: AM

[0248] - Logical Channel: DCCH

[0249] - Direction: network node 16 to WD 22 (e.g. UE)

[0250] RRCReconfiguration message

[0251]

[0252]

[0253]

[0254]

[0255]

[0256]

[0257]

[0258] The arrangement for the WD 22 to receive the above messages has been described. In some embodiments, the method implemented in the WD 22 may include one or more of the following after receiving the message:

[0259] WD 22 first performs a mobility procedure, that is, WD 22 accesses the target cell indicated in, for example, a HO command / synchronization reconfiguration (rather than conditional reconfiguration, such as CHO configuration or procedure); and / or

[0260] Only after accessing the target cell, WD 22 performs conditional reconfiguration based on the configuration provided in the message, and initiates actions during conditional reconfiguration.

[0261] As an example, in the context of this disclosure, the following ASN.1 structure can be assumed for conditional reconfigurations (e.g., CHO configurations) within an RRC Reconfiguration message, as shown in the previous step:

[0262] Conditional Reconfiguration

[0263] The IE Conditional Reconfiguration is used to add, modify, or release conditional handover configurations for each target candidate cell.

[0264] Conditional Reconfiguration information element

[0265]

[0266]

[0267] ConditionalReconfigurationId

[0268] The IE ConditionalReconfigurationId is used to identify the link between a trigger condition and an RRCReconfiguration that is to be applied upon fulfilment of the condition.

[0269] ConditionalReconfigurationId information element

[0270] -- ASN1START

[0271] -- TAG-CONDRECONFIGURATIONID-START

[0272] CondReconfigurationId ::= INTEGER (1..maxNrofCondReconf)

[0273] -- TAG-CONDRECONFIGURATIONID-STOP

[0274] -- ASN1STOP

[0275] CondReconfigurationToAddModList

[0276] The IE CondReconfigurationToAddModList concerns a list of conditional handover configurations to be added or modified, each entry having a measId (associated with a trigger condition configuration) and an associated RRCReconfiguration.

[0277] CondReconfigurationToAddModList information element

[0278]

[0279] CondReconfigurationPerTargetCandidate

[0280] The IE CondReconfigurationPerTargetCandidate contains a conditional reconfiguration for a target candidate cell, which includes a trigger condition configuration, which is a set of pointers to measurement identifiers, each measId having its own trigger condition, and an associated RRCReconfiguration in an octet string to be applied upon fulfilment of all conditions associated with the measurement identifiers.

[0281] CondReconfigurationPerTargetCandidate information element

[0282]

[0283] NOTE: For further study (FFS): Can the trigger condition refer to a list of measurement identifiers, e.g., SEQUENCE (SIZE (1..K)) OF Measld?

[0284] Then, in some embodiments, these previous steps can be patterned in the RRC specification by moving the conditional reconfiguration (e.g., CHO configuration) to be performed after the HO command that can be received. Thus, it is clear that the conditional reconfiguration (e.g., CHO configuration) is associated with (e.g., prepared by) the target cell that the WD 22 performs the handover to, as shown below (pay particular attention to the following bolded parts).

[0285] 5.3.5.3 Reception of RRCReconfiguration by the WD 22

[0286] The WD 22 can perform the following actions upon reception of the RRCReconfiguration or upon applying the stored RRCReconfiguration message to the conditional reconfiguration execution:

[0287] 1> if the RRCReconfiguration is received over other RAT (i.e., inter-RAT handover to NR):

[0288] 2> if the RRCReconfiguration does not include fullConfig and the WD 22 is connected to 5GC (i.e., incremental signaling during intra-5GC handover):

[0289] 3> re-use the source RAT SDAP and PDCP configurations if available (i.e., current SDAP / PDCP configurations for all RBs from the source E-UTRA RAT prior to reception of the inter-RAT HO RRCReconfiguration message).

[0290] 1> else:

[0291] 2> if the RRCReconfiguration includes fullConfig:

[0292] 3> perform the full configuration procedure as specified in 5.3.5.11;

[0293] 1> if the RRCReconfiguration includes masterCellGroup:

[0294] 2> perform cell group configuration for reception of the masterCellGroup according to 5.3.5.5;

[0295] 1> if the RRCReconfiguration includes masterKeyUpdate:

[0296] 2> perform the AS security key update procedure specified in 5.3.5.7;

[0297] 1> if the RRCReconfiguration includes sk-Counter:

[0298] 2> perform the security key update procedure specified in 5.3.5.7;

[0299] 1> if the RRCReconfiguration includes secondaryCellGroup:

[0300] 2> perform cell group configuration for the SCG according to 5.3.5.5;

[0301] 1> if the RRCReconfiguration includes mrdc-SecondaryCellGroupConfig:

[0302] 2> if the mrdc-SecondaryCellGroupConfig is set to setup:

[0303] 3> if the mrdc-SecondaryCellGroupConfig includes mrdc-ReleaseAndAdd:

[0304] 4> perform MR-DC release as specified in section 5.3.5.10;

[0305] 3> if the received mrdc-SecondaryCellGroup is set to nr-SCG:

[0306] 4> perform RRC reconfiguration according to 5.3.5.3 for the RRCReconfiguration message included in the nr-SCG;

[0307] 3> if the received mrdc-SecondaryCellGroup is set to eutra-SCG:

[0308] 4> perform RRC connection reconfiguration according to the provisions in subclause 5.3.5.3 of TS 36.331 for the RRCConnectionReconfiguration message included in eutra-SCG;

[0309] 2> else (mrdc-SecondaryCellGroupConfig is set to release):

[0310] 3> perform MR-DC release according to the provisions in subclause 5.3.5.10;

[0311] 1> if the RRCReconfiguration message includes radioBearerConfig:

[0312] 2> perform radio bearer configuration according to 5.3.5.6;

[0313] 1> if the RRCReconfiguration message includes radioBearerConfig2:

[0314] 2> perform radio bearer configuration according to 5.3.5.6;

[0315] 1> if the RRCReconfiguration message includes measConfig:

[0316] 2> perform the measurement configuration procedure according to the provisions in 5.5.2;

[0317] 1> if the RRCReconfiguration message includes dedicatedNAS-MessageList:

[0318] 2> forward each element of dedicatedNAS-MessageList to upper layers in the same order as listed;

[0319] 1> if the RRCReconfiguration message includes dedicatedSIB1-Delivery:

[0320] 2> perform actions upon reception of SIB1 according to the provisions in 5.2.2.4.2;

[0321] 1> if the RRCReconfiguration message includes dedicatedSystemInformationDelivery:

[0322] 2> perform actions upon reception of system information according to the provisions in 5.2.2.4;

[0323] 1> if the RRCReconfiguration message includes otherConfig:

[0324] 2> perform the other configuration procedures as specified in 5.3.5.9;

[0325] 1> if the RRCReconfiguration message includes conditionalReconfiguration:

[0326] 2> perform conditional reconfiguration as specified in 5.3.5.x;

[0327] NOTE: FFS confirmation of usage of enhanced version of RRCReconfiguration message to configure conditional handover.

[0328] 1> set the content of the RRCReconfigurationComplete message as follows:

[0329] NOTE: FFS whether to provide an exception to transmission of the RRCReconfigurationComplete message, i.e. not to be transmitted if only conditional reconfiguration is included in this message.

[0330] NOTE: FFS whether to provide an exception to transmission of the RRCReconfigurationComplete message, i.e. not to be transmitted in case this message contains CHO configuration and the reception fulfils the triggering condition.

[0331] 2> if the RRCReconfiguration includes masterCellGroup including reportUplinkTxDirectCurrent; or

[0332] 2> if the RRCReconfiguration includes secondaryCellGroup including reportUplinkTxDirectCurrent:

[0333] 3> include uplinkTxDirectCurrentList for each serving cell with UL;

[0334] 3> if the WD 22 is configured with a SUL carrier:

[0335] 4> include uplinkDirectCurrentBWP-SUL for each serving cell with SUL within uplinkTxDirectCurrentList;

[0336] 2> if the received RRCReconfiguration message includes mrdc-SecondaryCellGroupConfig with mrdc-SecondaryCellGroup set to eutra-SCG:

[0337] 3> include eutra-SCG-Response within scg-Response in accordance with TS 36.331 section 5.3.5.3;

[0338] 2> if the received RRCReconfiguration message includes mrdc-SecondaryCellGroupConfig with mrdc-SecondaryCellGroup set to nr-SCG:

[0339] 3> include nr-SCG-Response within scg-Response;

[0340] 1> if the WD 22 is configured with E-UTRA nr-SecondaryCellGroupConfig (MCG is E-UTRA):

[0341] 2> if the RRCReconfiguration is received via SRB1:

[0342] 3> submit the RRCReconfigurationComplete via E-UTRA RRC message embedded in E-UTRA MCG as specified in TS 36.331;

[0343] 3> if reconfigurationWithSync is included in spCellConfig of the SCG:

[0344] 4> initiate the random access procedure on the SpCell as specified in TS 38.321;

[0345] 3> otherwise:

[0346] 4> the procedure ends;

[0347] NOTE 1: The order in which the WD 22 sends the RRCConnectionReconfigurationComplete message and performs the random access procedure towards the SCG is left to WD implementation.

[0348] 2> other (RRCReconfiguration received via SRB3):

[0349] 3> submit the RRCReconfigurationComplete message to lower layers via SRB3 for transmission using the new configuration;

[0350] NOTE 2: In (NG)EN-DC and NR-DC, in case of RRCReconfiguration received over SRB1, random access is triggered by the RRC layer itself as there is not necessarily other UL transmission. In case of RRCReconfiguration received over SRB3, random access is triggered by the MAC layer as a result of the arrival of the RRCReconfigurationComplete.

[0351] 1> else if the RRCReconfiguration message is received within nr-SCG in mrdc-SecondaryCellGroup (NR SCG RRC reconfiguration),

[0352] 2> if reconfigurationWithSync is included in spCellConfig in nr-SCG:

[0353] 3> initiate the random access procedure on PSCell as specified in TS 38.321;

[0354] 2> else.

[0355] 3> the procedure ends;

[0356] 1> else if RRCReconfiguration is received over SRB3,

[0357] 2> submit the RRCReconfigurationComplete message to lower layers via SRB3 for transmission using the new configuration;

[0358] 1> else (mcg RRCReconfiguration):

[0359] 2> submit the RRCReconfigurationComplete message to lower layers via SRB1 for transmission using the new configuration;

[0360] 2> if this is the first RRCReconfiguration message after successfully completing the RRC re-establishment procedure:

[0361] 3> resume the suspended SRB2 and DRBs;

[0362] 1> if reconfigurationWithSync is included in spCellConfig of the MCG or SCG and when the MAC of the NR cell group successfully completes the random access procedure triggered above;

[0363] 2> stop timer T304 for this cell group;

[0364] 2> apply the parts of CQI reporting configuration, scheduling request configuration and Sounding RS configuration that do not require the WD 22 to know the SFN of the respective target SpCell (if any);

[0365] 2> apply the parts of measurement and radio resource configuration (e.g. measurement gaps, periodic CQI reporting, scheduling request configuration, Sounding RS configuration) that require the WD 22 to know the SFN of the respective target SpCell (if any) after acquiring the SFN of the target SpCell;

[0366] 2> if reconfigurationWithSync is included in spCellConfig of the MCG:

[0367] 3> if T390 is running:

[0368] 4> stop timer T390 for all access categories;

[0369] 4> perform the actions specified in 5.3.14.4.

[0370] 3> if RRCReconfiguration does not include dedicatedSIB1-Delivery and

[0371] 3> if the active downlink BWP indicated by firstActiveDownlinkBWP-Id for the target SpCell of the MCG has common search space configured by

[0372] searchSpaceSIB1:

[0373] 4> acquire SIB1 of the target SpCell of the MCG scheduled according to the provisions in TS 38.213;

[0374] 4> upon acquiring SIB1, perform the actions specified in clause 5.2.2.4.2;

[0375] 2> delete all entries within VarConditionalReconfiguration (if any);

[0376] NOTE: FFS if any WD autonomous actions related to VarMeasConfig associated with conditional handover need to be specified.

[0377] NOTE: FFS to confirm that CHO configuration is handled using WD variables, e.g. VarConditionalReconfiguration.

[0378] 2> the procedure ends.

[0379] NOTE 3: If the WD 22 can acquire the broadcasted SIB1 without disturbing unicast data reception, i.e. broadcast and unicast beams are quasi co-located, then only the WD 22 needs to acquire the broadcasted SIB1.

[0380] 5.3.5.x Conditional reconfiguration

[0381] 5.3.5.x.1 Overview

[0382] In some embodiments, the network node 16 configures the WD 22 with a conditional reconfiguration RRCReconfiguration per target cell candidate that is only applied upon meeting the associated trigger condition configuration. The network node 16 provides the configuration parameters in the ConditionalReconfiguration IE.

[0383] In some embodiments, the WD 22 performs one or more of the following actions based on the received ConditionalReconfiguration IE:

[0384] 1> if the received condReconfiguration includes condReconfigurationToRemoveList:

[0385] 2> perform the conditional reconfiguration removal procedure as specified in 5.3.5.x.2;

[0386] 1> if the received condReconfiguration includes condReconfigurationToAddModList:

[0387] 2> perform the conditional reconfiguration addition / modification procedure as specified in 5.3.5.x.3.

[0388] 5.3.5.x.2 Conditional reconfiguration removal

[0389] The WD 22 can:

[0390] 1> for each condReconfigurationId included in the condReconfigurationToRemoveList (conditional reconfiguration remove list) that is part of the current WD 22 configuration in the received VarConditionalReconfiguration:

[0391] 2> stop monitoring the trigger condition linked to the measurement identification;

[0392] 2> remove the entry with matching condReconfigurationId from the condReconfigurationList (conditional reconfiguration list) within the VarConditionalReconfiguration;

[0393] NOTE: If the condReconfigurationToRemoveList includes any condReconfigurationId values that are not part of the current WD 22 configuration, the WD 22 does not consider the message as an error.

[0394] NOTE: FFS if any WD autonomous removal of measurement configuration after CHO configuration removal is defined.

[0395] 5.3.5.x.3 Conditional reconfiguration addition / modification

[0396] The WD 22 can:

[0397] 1> for each condReconfigurationId included in the condReconfigurationToAddModList (conditional reconfiguration addition modification list) received:

[0398] 2> if there is an entry with matching condReconfigurationId in the condReconfigurationList in the VarConditionalReconfiguration:

[0399] 3> stop monitoring the trigger condition linked to the measurement identification;

[0400] 3> replace the entry with the received values for this condReconfigurationId;

[0401] NOTE: FFS confirmation that RRCReconfiguration is also replaced, and handling if not present.

[0402] 2> else:

[0403] 3> add a new entry for this condReconfigurationId within VarConditionalReconfiguration;

[0404] 3> store the associated RRCReconfiguration in VarConditionalReconfiguration;

[0405] 2> monitor the triggering condition associated with the measurement identity of this condReconfigurationId as specified in 5.5.4

[0406] 5.3.5.x.4 Conditional reconfiguration execution

[0407] For measld(s) for which the triggering condition(s) of the conditional reconfiguration(s) are satisfied, the WD 22 can:

[0408] 1> for each condReconfigurationId within VarConditionalReconfiguration that has a measld associated with the stored RRCReconfiguration:

[0409] 2> if all the triggering conditions of this condReconfigurationId are satisfied:

[0410] 3> consider the target cell candidate associated with this condReconfigurationId within the stored RRCReconfiguration as a triggered cell;

[0411] 1> if there is more than one triggered cell:

[0412] 2> FFS;

[0413] NOTE: FFS on cell selection in case multiple cells satisfy the triggering condition of the conditional reconfiguration.

[0414] 1> else:

[0415] 2> consider this cell as the selected cell for the conditional reconfiguration;

[0416] 1> upon selecting one target candidate cell for conditional reconfiguration, proceed with:

[0417] 2> if the WD 22 is able to comply with the stored RRCReconfiguration for the selected cell:

[0418] 3> Apply the RRCReconfiguration of the application storage as specified in 5.3.5.3;

[0419] 2> Otherwise:

[0420] 3> As specified in 5.3.5.8, the reconfiguration failure process should be executed;

[0421] Note: Whether FFS performs the target candidate RRCReconfiguration conformance after receiving a conditional reconfiguration.

[0422] In some embodiments, for example, in Figure 12 The diagram illustrates the signaling flow focusing on WD 22. Although this example is described in relation to the HO process, the principles can also be applied to other types of mobility processes.

[0423] Figure 12 The diagram illustrates that in step S142, WD 22 sends an RRC measurement report to source network node 16a. Then, in step S144, source network node 16a can then send a request to WD 22 to perform a mobility procedure, for example, by sending a HO preparation message including the current configuration information of WD 22 to target network node 16b. In step S146, target network node 16b is able to perform a CHO and can determine that it is configured for WD 22. Then, in step S148, target network node 16b can then send an acknowledgment (ACK) message to source network node 16a. The ACK message may include, for example, a configuration for RRC reconfiguration to be used in a target cell supported by target network node 16b, and, for example, a conditional reconfiguration (e.g., CHO configuration) associated with a target candidate cell corresponding to / prepared by target network node 16b. In step S150, source network node 16a may send an RRC reconfiguration to WD 22. The RRC reconfiguration may include an indication to perform a mobility procedure (e.g., synchronous reconfiguration) and a conditional reconfiguration. In some embodiments, synchronous reconfiguration can be considered a HO command, and CHO configuration can be included in conditional reconfiguration. Then, in step S152, WD 22 can send an RRC reconfiguration complete message to the target network node 16b. In step S154, WD 22 can begin executing at least one action based on conditional reconfiguration, such as monitoring CHO triggering conditions, like... Figure 12 As shown in the image.

[0424] In some embodiments, this disclosure provides a method for a reconfiguration process, performed by a target network node 16b (also referred to as the source gNodeB), including a conditional configuration (e.g., CHO configuration), the method comprising one or more of the following:

[0425] - receiving the current configuration of the WD 22 (i.e. the configuration used in the source cell supported by the source network node 16a) from the source node 16a (e.g. in the handover preparation procedure) in the handover / synchronization reconfiguration / PSCell change request message; the request message can include the measurements performed by the WD 22 and reported e.g. in the inter-node RRM container;

[0426] - preparing conditional reconfigurations for the WD 22, e.g. by configuring CHO for this incoming WD 22; thus, including CHO configuration in the WD 22 target configuration according to the target network node 16b, to be provided to the WD 22 by the source network node 16a; including the conditional reconfigurations (e.g. associated with target candidate cells) and the target configuration of the WD 22 (e.g. the RRC reconfiguration to be used by the WD 22 after accessing the target cell supported by the target network node 16b) in the inter-node message from the target network node 16b to the source network node 16a included in the HO preparation procedure;

[0427] o this decision by the target network node 16b to include conditional reconfigurations can possibly be determined based on the measurements from the WD 22 included in the inter-node message from the source network node 16a in the HO request, as described above.

[0428] - if a target candidate cell associated with a conditional reconfiguration to be given to the WD 22 is not supported by the same target network node 16b (e.g. a cell supported by another neighbour network node), the target network node 16b can initiate a CHO preparation procedure with the target candidate network node (which can be a HO preparation procedure with an indication that this is for CHO) by sending the target WD 22 configuration (i.e. the WD 22 configuration to be used in the target cell after the WD 22 accesses the target cell). To this end, the target network node 16b can create a WD 22 complete configuration based on the current configuration of the WD 22 in the source cell and on what the target network node (e.g. the network node 16b) wants to modify, so that each target candidate network node is aware of the types of reconfigurations available for preparing these conditional reconfigurations. In another alternative, only complete configurations are allowed to be prepared through the target candidate network nodes associated with the target candidate cells in the HO.

[0429] - sends the configuration of the WD 22 (e.g. with a container containing the RRC reconfiguration with sync reconfiguration and conditional reconfigurations) to the source node (e.g. network node 16a) (e.g. ACK in handover preparation procedure) to be used in the target upon handover execution, including CHO configuration. Each conditional reconfiguration is per target candidate cell and includes a trigger condition configuration (which can be one or more measurement identities associated with a measurement configuration) and a target candidate cell configuration (which can be an RRC reconfiguration, either a full configuration or a delta configuration with a target configuration of the WD 22 to be used after the WD 22 accesses the target cell as a baseline).

[0430] - receives the RRC reconfiguration complete message from the incoming WD 22 (where the WD 22 uses the target configuration of the WD 22) and understands that the incoming WD 22 performs actions according to the provided conditional reconfigurations, e.g. monitors the configured trigger conditions.

[0431] In some embodiments, as an example, Figure 13 A signaling flow focusing on examples on network node 16 aspects (signaling between source NN 16a, target NN 16b and target candidate NN 16c for CHO) is shown in FIG. 15. Figure 13 It is shown that in step S156 the WD 22 sends the RRC measurement report to the source network node 16a. Then, in step S158, the source network node 16a sends the HO preparation message including the configuration information of the current WD 22 to the target network node 16b. In step S160, the target network node 16b can perform CHO and can determine to prepare conditional reconfigurations for the WD 22, e.g. to give the WD 22 CHO configuration. In step S162, the target network node 16b can send the CHO preparation message to the target candidate network node 16c. The CHO preparation can include the configuration of the WD 22 to be used in the target cell. In step S164, the target candidate network node 16c can send the ACK including the configuration to be finally used for the target candidate cell, e.g. the CHO configuration associated with the target candidate cell.

[0432] In step S166, the target network node 16b can then send an acknowledgement (ACK) message to the source network node 16a. The ACK message can include the configuration for use in the target cell, e.g., RRCReconfiguration, in addition to the conditional reconfiguration associated with the target candidate cell from the target candidate network node 16c. In step S168, the source network node 16a can send the RRCReconfiguration to the WD 22. The RRCReconfiguration can include the synchronization reconfiguration (HO command) as well as the conditional reconfiguration from the target candidate network node 16c. In step S170, the WD 22 can then send an RRCReconfigurationComplete message to the target network node 16b. In step S172, the WD 22 can start performing monitoring of the CHO trigger condition, e.g. Figure 13 as shown in FIG. 13.

[0433] In general, in case of handover (synchronization reconfiguration) failure, a reestablishment will occur. It is a working assumption in RAN2 that when reestablishing and the WD 22 selects a cell with configured CHO, the WD 22 is allowed to perform handover to that cell instead of reestablishment. In the present disclosure, the WD 22 will be possibly configured with both CHO target cells from the source network node (e.g., network node 16a) and CHO target cells from the target network node (e.g., network node 16b). Some embodiments of the present disclosure describe allowing the WD 22 to perform handover to a cell (e.g., candidate cell). This can be performed in the procedure text or as an explicit indication that the WD 22 is allowed to use the CHO target cell from the source network node 16a or the CHO target cell from the target network node 16b or both. See the example of implementation in the procedure text in bold and underlined in the following sections in TS 38.331:

[0434] 5.3.5.5 Reception of RRCReconfiguration by the WD 22

[0435] The WD 22 (e.g., UE) can perform the following actions upon reception of the RRCReconfiguration or upon applying the stored RRCReconfiguration message via conditional reconfiguration execution:

[0436] 1> if the RRCReconfiguration is received via other RAT (i.e., inter-RAT handover to NR):

[0437] 2> if the RRCReconfiguration does not include fullConfig and the WD 22 is connected to 5GC (i.e., incremental signaling during intra-5GC handover):

[0438] 3> if available, re-use the source SDAP and PDCP configuration (i.e. the current SDAP / PDCP configuration for all RBs from source E-UTRA RAT prior to receiving the inter-RAT HO RRCReconfiguration message);

[0439] 1> else:

[0440] 2> if the RRCReconfiguration includes fullConfig:

[0441] 3> perform the full configuration procedure as specified in 5.3.5.11;

[0442] 1> if the RRCReconfiguration includes masterCellGroup:

[0443] 2> perform the cell group configuration for the masterCellGroup for reception according to 5.3.5.5;

[0444] 1> if the RRCReconfiguration includes masterKeyUpdate:

[0445] 2> perform the AS security key update procedure as specified in 5.3.5.7;

[0446] 1> if the RRCReconfiguration includes sk-Counter:

[0447] 2> perform the security key update procedure as specified in 5.3.5.7;

[0448] 1> if the RRCReconfiguration includes secondaryCellGroup:

[0449] 2> perform the cell group configuration for the SCG according to 5.3.5.5;

[0450] 1> if the RRCReconfiguration includes mrdc-SecondaryCellGroupConfig:

[0451] 2> if the mrdc-SecondaryCellGroupConfig is set to setup:

[0452] 3> if the mrdc-SecondaryCellGroupConfig includes mrdc-ReleaseAndAdd:

[0453] 4> perform the MR-DC release as specified in section 5.3.5.10;

[0454] 3> if the received mrdc-SecondaryCellGroup is set to nr-SCG:

[0455] 4> perform RRC reconfiguration according to 5.3.5.3 for the RRCReconfiguration message included in the nr-SCG;

[0456] 3> if the received mrdc-SecondaryCellGroup is set to eutra-SCG:

[0457] 4> perform RRC connection reconfiguration according to the provisions in clause 5.3.5.3 of TS 36.331 for the RRCConnectionReconfiguration message included in the eutra-SCG;

[0458] 2> else (mrdc-SecondaryCellGroupConfig is set to release):

[0459] 3> perform MR-DC release according to the provisions in clause 5.3.5.10;

[0460] 1> if the RRCReconfiguration message includes radioBearerConfig:

[0461] 2> perform radio bearer configuration according to 5.3.5.6;

[0462] 1> if the RRCReconfiguration message includes radioBearerConfig2:

[0463] 2> perform radio bearer configuration according to 5.3.5.6;

[0464] 1> if the RRCReconfiguration message includes measConfig:

[0465] 2> perform the measurement configuration procedure as specified in 5.5.2;

[0466] 1> if the RRCReconfiguration message includes dedicatedNAS-MessageList:

[0467] 2> forward each element of dedicatedNAS-MessageList to upper layers in the order listed;

[0468] 1> if the RRCReconfiguration message includes dedicatedSIB1-Delivery:

[0469] 2> perform the action upon reception of SIB1 reception as specified in 5.2.2.4.2;

[0470] 1> if the RRCReconfiguration message includes dedicatedSystemInformationDelivery:

[0471] 2> perform the action upon reception of system information as specified in 5.2.2.4;

[0472] 1> if the RRCReconfiguration message includes otherConfig:

[0473] 2> perform the other configuration procedures as specified in 5.3.5.9;

[0474] 1> if the RRCReconfiguration message includes conditionalReconfiguration:

[0475] 2> perform conditional reconfiguration as specified in 5.3.5.x;

[0476] NOTE: FFS confirmation of the use of an enhanced version of the RRCReconfiguration message for configuration of conditional handover.

[0477] NOTE: If the RRCReconfiguration message includes both reconfigurationwithSync and conditionalReconfiguration, the WD 22 can consider all conditional handover target cells when the reconfigurationwithSync procedure fails. ​ ​

[0478] 1> set the content of the RRCReconfigurationComplete message as follows:

[0479] NOTE: FFS whether we need an exception for the transmission of the RRCReconfigurationComplete message, i.e. if only conditional reconfiguration is included in this message, it is not transmitted.

[0480] NOTE: FFS whether we need an exception for the transmission of the RRCReconfigurationComplete message, i.e. in case this message contains CHO configuration and the reception fulfils the triggering condition, it is not transmitted.

[0481] 2> if the RRCReconfiguration includes a masterCellGroup that contains reportUplinkTxDirectCurrent; or

[0482] 2> if the RRCReconfiguration includes a secondaryCellGroup that contains reportUplinkTxDirectCurrent:

[0483] 3> include uplinkTxDirectCurrentList for each serving cell with UL;

[0484] 3> if the WD 22 is configured with a SUL carrier:

[0485] 4> include uplinkDirectCurrentBWP-SUL for each serving cell with SUL within uplinkTxDirectCurrentList;

[0486] 2> if the received RRCReconfiguration message includes a mrdc-SecondaryCellGroupConfig with a mrdc-SecondaryCellGroup set to eutra-SCG:

[0487] 3> include eutra-SCG-Response within scg-Response according to TS 36.331 subclause 5.3.5.3;

[0488] 2> if the received RRCReconfiguration message includes a mrdc-SecondaryCellGroupConfig with a mrdc-SecondaryCellGroup set to nr-SCG:

[0489] 3> include nr-SCG-Response within scg-Response;

[0490] 1> if the WD 22 is configured with E-UTRA nr-SecondaryCellGroupConfig (MCG is E-UTRA):

[0491] 2> if the RRCReconfiguration is received via SRB1:

[0492] 3> submit RRCReconfigurationComplete via E-UTRA MCG embedded in E-UTRA RRC message RRCConnectionReconfigurationComplete as specified in TS 36.331;

[0493] 3> if reconfigurationWithSync is included in spCellConfig of SCG:

[0494] 4> initiate random access procedure on SpCell as specified in TS 38.321;

[0495] 3> otherwise:

[0496] 4> procedure ends;

[0497] NOTE 1: The order in which the WD 22 sends the RRCConnectionReconfigurationComplete message and performs the random access procedure towards the SCG is left to WD implementation.

[0498] 2> otherwise (RRCReconfiguration received via SRB3):

[0499] 3> submit RRCReconfigurationComplete message to lower layers via SRB3 for transmission using the new configuration;

[0500] NOTE 2: In (NG)EN-DC and NR-DC, in case of RRCReconfiguration received over SRB1, the random access is triggered by the RRC layer itself as there is not necessarily other UL transmission. In case of RRCReconfiguration received over SRB3, the random access is triggered by the MAC layer as a result of the arrival of the RRCReconfigurationComplete.

[0501] 1> else if the RRCReconfiguration message is received in nr-SCG in mrdc-SecondaryCellGroup (NR SCG RRC reconfiguration),

[0502] 2> if reconfigurationWithSync is included in spCellConfig in nr-SCG:

[0503] 3> initiate random access procedure on PSCell as specified in TS 38.321;

[0504] 2> else.

[0505] 3> procedure ends;

[0506] 1> else if RRCReconfiguration is received over SRB3:

[0507] 2> submit the RRCReconfigurationComplete message to lower layers over SRB3 for transmission using the new configuration;

[0508] 1> else (mcg RRCReconfiguration):

[0509] 2> submit the RRCReconfigurationComplete message to lower layers over SRB1 for transmission using the new configuration;

[0510] 2> if this is the first RRCReconfiguration message after successfully completing the RRC re-establishment procedure:

[0511] 3> resume the suspended SRB2 and DRBs;

[0512] 1> if reconfigurationWithSync is included in spCellConfig of MCG or SCG and when the MAC of the NR cell group successfully completes the random access procedure triggered above;

[0513] 2> stop timer T304 for that cell group;

[0514] 2> apply the parts of CQI reporting configuration, scheduling request configuration and Sounding RS configuration that do not require the WD 22 to know the SFN of the respective target SpCell (if any);

[0515] 2> apply the parts of measurement and radio resource configuration (e.g. measurement gaps, periodic CQI reporting, scheduling request configuration, Sounding RS configuration) that require the WD 22 to know the SFN of the respective target SpCell (if any) after acquiring the SFN of that target SpCell;

[0516] 2> if reconfigurationWithSync is included in spCellConfig of MCG:

[0517] 3> if T390 is running:

[0518] 4> stop timer T390 for all access categories;

[0519] 4> perform the actions as specified in 5.3.14.4.

[0520] 3> if the RRCReconfiguration does not include dedicatedSIB1-Delivery and

[0521] 3> if the active downlink BWP indicated by firstActiveDownlinkBWP-Id of the target SpCell for MCG has common search space configured by searchSpaceSIB1:

[0522] 4> acquire SIB1 of the target SpCell of MCG scheduled as specified in TS 38.213;

[0523] 4> upon acquiring SIB1, perform the actions specified in section 5.2.2.4.2;

[0524] 2> remove all entries within VarConditionalReconfiguration, if any;

[0525] NOTE: FFS whether we need to specify any WD autonomous actions regarding VarMeasConfig associated with conditional handover.

[0526] NOTE: FFS to confirm the use of WD variables to handle CHO configuration, e.g. VarConditionalReconfiguration.

[0527] 2> the procedure ends.

[0528] NOTE 3: If the WD 22 can acquire the broadcasted SIB1 without interruption of unicast data reception, i.e. broadcast and unicast beams are quasi-colocated, then the WD 22 only needs to acquire the broadcasted SIB1.

[0529] Additionally, some embodiments can include one or more of the following:

[0530] Embodiment A1. A network node configured to communicate with a wireless device (WD), the network node configured to perform one or more of the following, and / or comprising a radio interface and / or comprising processing circuitry configured to perform one or more of the following:

[0531] receive, from a source network node, a handover (HO) preparation message in a HO procedure, the HO preparation message comprising a current configuration of the WD in a source cell;

[0532] determine a conditional handover (CHO) configuration for the WD; and

[0533] send, to the source network node, a message comprising the determined CHO configuration.

[0534] Embodiment A2. The network node of Embodiment A1, wherein the network node and / or radio interface and / or processing circuitry is further configured to:

[0535] receive a radio resource control (RRC) reconfiguration complete message from the WD; and

[0536] as a result of receiving the RRC reconfiguration complete message, communicate with the WD based on an assumption that the WD is operating according to the CHO configuration.

[0537] Embodiment B1. A method implemented in a network node, the method comprising one or more of:

[0538] receiving, from a source network node, a handover (HO) preparation message in a handover (HO) procedure, the HO preparation message comprising a current configuration of a WD in a source cell;

[0539] determining a conditional handover (CHO) configuration for the WD; and

[0540] sending a message to the source network node, the message comprising the determined CHO configuration.

[0541] Embodiment B2. The method of Embodiment B1, further comprising:

[0542] receiving a radio resource control (RRC) reconfiguration complete message from the WD; and

[0543] as a result of receiving the RRC reconfiguration complete message, communicating with the WD based on an assumption that the WD is operating according to the CHO configuration.

[0544] Embodiment C1. A wireless device (WD) configured to communicate with a network node, the WD configured to perform one or more of the following, and / or comprising a radio interface and / or processing circuitry configured to perform one or more of the following:

[0545] receiving a message, the message being a radio resource control (RRC) reconfiguration message comprising a conditional handover (CHO) configuration and an indication of a handover (HO) command, the CHO prepared by a target network node and the HO command prepared by a source network node;

[0546] in response to the received message, attempting to access the target network node indicated in the HO command; and / or

[0547] as a result of accessing the target network node, performing a CHO according to the CHO configuration in the received message.

[0548] Embodiment C2. The WD of Embodiment C1, wherein the WD and / or radio interface and / or processing circuitry is further configured to:

[0549] in response to a HO failure when attempting to access the target network node, selecting a candidate cell indicated in the CHO configuration and performing a handover of the WD to the selected candidate cell.

[0550] Embodiment D1. A method implemented in a wireless device (WD), the method comprising one or more of the following operations:

[0551] receiving a message, the message being a radio resource control (RRC) reconfiguration message comprising a conditional handover (CHO) configuration and an indication of a handover (HO) command, the CHO being prepared by a target network node and the HO command being prepared by a source network node;

[0552] in response to the received message, attempting to access the target network node indicated in the HO command; and / or

[0553] as a result of the accessing of the target network node, performing a CHO according to the CHO configuration in the received message.

[0554] Embodiment D2. The method according to embodiment D1, further comprising:

[0555] in response to a HO failure when attempting to access the target network node, selecting a candidate cell indicated in the CHO configuration and performing a handover of the WD to the selected candidate cell.

[0556] As those skilled in the art will appreciate, the concepts described herein can be embodied as a method, data processing system, computer program product, and / or computer storage media storing executable computer program. Accordingly, the concepts described herein can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module”. Any process, step, action and / or functionality described herein can be performed by, and / or associated with, a corresponding module which can be implemented in software and / or firmware and / or hardware. Furthermore, the disclosure can take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in it. Any suitable tangible computer readable medium can be utilized including a hard disk, CD-ROM, electronic storage, optical storage or magnetic storage.

[0557] Some embodiments are described herein with reference to flowchart illustrations and / or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer (with the processor thus being special purpose machinery), a special purpose computer or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0558] These computer program instructions can also be stored in a computer-readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions means which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0559] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0560] It will be understood that the functions / acts marked with parentheses can occur in different orders than those described in the operational illustrations. For example, two blocks connected in series can in fact be executed substantially concurrently, or the blocks can sometimes be executed in reverse order, depending upon the functionality / acts involved. Although some diagrams include arrows on communication paths to show the primary flow of communication, it is to be understood that communication can occur in reverse order to that depicted by the arrows.

[0561] Computer program code for carrying out operations of the concepts described herein can be written in an object oriented programming language such as Java® or C++. However, the computer program code for carrying out operations of the disclosure can also be written in a conventional procedural programming languages, such as the "C" programming language. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer can be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0562] In light of the above description and drawings, numerous different embodiments have been disclosed herein. It will be understood that describing and illustrating every combination and subcombination of the embodiments would be an inappropriate repetition of the specification and would cause confusion. Thus, all the embodiments can be combined in any way and / or combination, and the specification, including the drawings, should be construed to cover all such combinations and subcombinations and the ways and means of making and using them, and to support the obtaining of any such patent claims therefor.

[0563] Those skilled in the art will understand that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mentioned contrary, all drawings are not to scale. Modifications and changes can be made in the above teachings without departing from the scope of the appended claims.

Claims

1. A method implemented at a wireless device, WD, (22) configured to communicate with a network node (16a), the method comprising: receiving (S140) at least one radio resource control, RRC, reconfiguration message, the at least one RRC reconfiguration message comprising a conditional reconfiguration and an indication that the wireless device (22) is to perform a mobility procedure, the indication of the mobility procedure being indicative of performing the mobility procedure from a source cell supported by the network node (16a) to a target cell supported by a target network node (16b), the conditional reconfiguration being associated with a target candidate cell corresponding to the target network node (16b), and as a result of a failure to attempt access to the target cell, selecting a candidate cell associated with a conditional handover and performing a handover of the wireless device (22) to the selected candidate cell; wherein an explicit indication to the wireless device (22) indicates that, as a result of a failure to attempt access to the target cell, the candidate cell is selected from a first plurality of candidate cells associated with the network node (16a) supporting the source cell or from the first plurality of candidate cells associated with the network node (16a) supporting the source cell and a second plurality of candidate cells associated with the target network node (16b).

2. The method of claim 1, further comprising: upon receiving the at least one RRC reconfiguration message, performing the mobility procedure indicated in the received at least one RRC reconfiguration by attempting access to the target cell.

3. The method of claim 2, further comprising: as a result of accessing the target cell, performing at least one action in accordance with the conditional reconfiguration included in the received at least one RRC reconfiguration.

4. The method of claim 1, wherein, selecting the candidate cell associated with the conditional handover comprises: as a result of a failure to attempt access to the target cell, selecting the candidate cell from at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and the target network node (16b).

5. The method of any one of claims 1 to 4, wherein, selecting the candidate cell associated with the conditional handover comprises: as a result of a failure to attempt access to the target cell, selecting the candidate cell from at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and the network node (16a) supporting the source cell.

6. The method of any one of claims 1-4, wherein, the conditional reconfiguration and the indication to perform the mobility procedure are both included in a same RRC reconfiguration message.

7. The method of claim 6, wherein, the explicit indication to the wireless device (22) indicates that the conditional reconfiguration included in the same RRC reconfiguration message is performed only after accessing the target cell in accordance with the mobility procedure indicated in the same RRC reconfiguration message.

8. The method of claim 1, wherein, the conditional reconfiguration and the indication to perform the mobility procedure are prohibited in a same RRC reconfiguration message.

9. The method of claim 1, further comprising: when the indication of the conditional reconfiguration and the execution of the mobility procedure are comprised in a same RRC reconfiguration message, performing an RRC re-establishment procedure instead of the indicated mobility procedure and the conditional reconfiguration.

10. The method of any one of claims 1-4, wherein, the mobility procedure is a handover of the wireless device (22) from the source cell to the target cell.

11. The method of any one of claims 1-4, wherein, the mobility procedure corresponds to at least one of a request to add and change a primary secondary cell, PSCell, for the wireless device (22).

12. The method of any one of claims 1-4, wherein, the indication of the execution of the mobility procedure is comprised in one of a synchronization reconfiguration field and a mobility control information field comprised in the at least one RRC reconfiguration message.

13. The method of any one of claims 1-4, further comprising: receiving signaling indicating one of an addition, a modification, and a release of the conditional reconfiguration of the target candidate cell prepared by the target network node (16b).

14. The method of any one of claims 1-4, wherein, the conditional reconfiguration associated with the target candidate cell comprises a trigger condition configuration comprising a set of pointers to at least one measurement identifier, and each measurement identifier of the at least one measurement identifier is associated with at least one trigger condition and an RRC reconfiguration.

15. The method of any of claims 1-4, further comprising: determining not to send an RRC reconfiguration complete message based at least in part on a presence of the conditional reconfiguration associated with the target candidate cell in the at least one RRC reconfiguration message.

16. A method implemented in a network node (16b), the method comprising: receiving (S134) a request to perform a mobility procedure for a wireless device (22) from a source cell supported by a source network node (16a) to a target cell supported by the network node (16b), the request comprising a current configuration for the wireless device (22) in the source cell; upon receiving the request, determining (S136) to prepare a conditional reconfiguration for the wireless device (22); and sending (S138) the conditional reconfiguration for the wireless device (22) and a radio resource control, RRC, reconfiguration, the RRC reconfiguration being associated with the requested mobility procedure from the source cell to the target cell supported by the network node (16b), and the conditional reconfiguration being associated with a target candidate cell determined by the network node (16b); wherein the target candidate cell associated with the conditional reconfiguration is selectable by the wireless device (22) for a handover of the wireless device (22) to the target candidate cell upon a failure to access the target cell indicated in the requested mobility procedure; wherein the explicit indication indicates to the wireless device (22) that the candidate cell is selected from a first plurality of candidate cells associated with the source network node (16a) supporting the source cell as a result of a failure to attempt access to the target cell, or from a first plurality of candidate cells associated with the network node (16a) supporting the source cell and a second plurality of candidate cells associated with the network node (16b).

17. The method of claim 16, wherein, The wireless device (22) is to use the conditional reconfiguration after accessing the target cell indicated in the requested mobility procedure.

18. The method of claim 16, wherein, The target candidate cell associated with the conditional reconfiguration is not selectable by the wireless device (22) for handover of the wireless device (22) to the target candidate cell after a failure to access the target cell indicated in the requested mobility procedure.

19. The method of any one of claims 16-18, wherein, The mobility procedure is a handover of the wireless device (22) from the source cell to the target cell.

20. The method of any one of claims 16-18, wherein, The mobility procedure corresponds to at least one of a request to add and change a primary secondary cell, PSCell, for the wireless device (22).

21. The method of any one of claims 16-18, wherein, Determining the conditional reconfiguration to prepare for the wireless device (22) is based at least in part on measurements from the wireless device (22) included in the received request to perform the mobility procedure.

22. The method of any one of claims 16-18, wherein, Preparing the conditional reconfiguration for the wireless device (22) includes: sending the RRC reconfiguration for the wireless device (22) to a target candidate network node (16c) supporting the target candidate cell; and obtaining the conditional reconfiguration from the target candidate network node (16c), the conditional reconfiguration being based at least in part on the sent RRC reconfiguration.

23. The method of any one of claims 16-18, wherein, At least one of the conditional reconfiguration associated with the target candidate cell and the RRC reconfiguration associated with the target cell of the mobility procedure is based at least in part on a received current configuration for the wireless device (22) in the source cell.

24. The method of any of claims 16-18, further comprising: receiving an RRC reconfiguration complete message; and communicating with the wireless device (22) based on an assumption that the wireless device (22) is operating according to the conditional reconfiguration as a result of the received RRC reconfiguration complete message.

25. A wireless device, WD, (22) configured to communicate with a network node (16a), the wireless device (22) comprising processing circuitry (84), the processing circuitry (84) configured to cause the wireless device (22) to: receive at least one radio resource control, RRC, reconfiguration message, the at least one RRC reconfiguration message including a conditional reconfiguration and an indication that the wireless device (22) is to perform a mobility procedure, the indication that the mobility procedure is to be performed indicates performance of the mobility procedure from a source cell supported by the network node (16a) to a target cell supported by a target network node (16b), The wireless device (22) is to use the conditional reconfiguration after accessing the target cell indicated in the requested mobility procedure. The target candidate cell associated with the conditional reconfiguration is not selectable by the wireless device (22) for handover of the wireless device (22) to the target candidate cell after a failure to access the target cell indicated in the requested mobility procedure. The mobility procedure is a handover of the wireless device (22) from the source cell to the target cell. The mobility procedure corresponds to at least one of a request to add and change a primary secondary cell, PSCell, for the wireless device (22). Determining the conditional reconfiguration to prepare for the wireless device (22) is based at least in part on measurements from the wireless device (22) included in the received request to perform the mobility procedure. Preparing the conditional reconfiguration for the wireless device (22) includes: sending the RRC reconfiguration for the wireless device (22) to a target candidate network node (16c) supporting the target candidate cell; and obtaining the conditional reconfiguration from the target candidate network node (16c), the conditional reconfiguration being based at least in part on the sent RRC reconfiguration. At least one of the conditional reconfiguration associated with the target candidate cell and the RRC reconfiguration associated with the target cell of the mobility procedure is based at least in part on a received current configuration for the wireless device (22) in the source cell.

24. The method of any of claims 16-18, further comprising: receiving an RRC reconfiguration complete message; and communicating with the wireless device (22) based on an assumption that the wireless device (22) is operating according to the conditional reconfiguration as a result of the received RRC reconfiguration complete message.

25. A wireless device, WD, (22) configured to communicate with a network node (16a), the wireless device (22) comprising processing circuitry (84), the processing circuitry (84) configured to cause the wireless device (22) to: receive at least one radio resource control, RRC, reconfiguration message, the at least one RRC reconfiguration message including a conditional reconfiguration and an indication that the wireless device (22) is to perform a mobility procedure, the indication that the mobility procedure is to be performed indicates performance of the mobility procedure from a source cell supported by the network node (16a) to a target cell supported by a target network node (16b), the conditional reconfiguration is associated with a target candidate cell corresponding to the target network node (16b), and selecting the candidate cell associated with the conditional handover as a result of a failure to access the target cell, and performing a handover of the wireless device (22) to the selected candidate cell; wherein, the explicit indication indicates to the wireless device (22) that the candidate cell is selected from a first plurality of candidate cells associated with the network node (16a) supporting the source cell, or from a first plurality of candidate cells associated with the network node (16a) supporting the source cell and a second plurality of candidate cells associated with the target network node (16b), as a result of a failure to access the target cell.

26. The wireless device (22) of claim 25, wherein, the processing circuitry (84) is further configured to cause the wireless device (22) to: perform the mobility procedure indicated in the received at least one RRC reconfiguration by attempting to access the target cell upon receiving the at least one RRC reconfiguration message.

27. The wireless device (22) of claim 26, wherein, the processing circuitry (84) is further configured to cause the wireless device (22) to: perform at least one action in accordance with the conditional reconfiguration contained in the received at least one RRC reconfiguration as a result of accessing the target cell.

28. The wireless device (22) of claim 25, wherein, the processing circuitry (84) is configured to cause the wireless device (22) to select the candidate cell associated with the conditional handover by being configured to cause the wireless device (22) to: select the candidate cell from at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and the target network node (16b), as a result of a failure to access the target cell.

29. The wireless device (22) of any one of claims 25-28, wherein, the processing circuitry (84) is configured to cause the wireless device (22) to select the candidate cell associated with the conditional handover by being configured to cause the wireless device (22) to: select the candidate cell from at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and the network node (16a) supporting the source cell, as a result of a failure to access the target cell.

30. The wireless device (22) of any one of claims 25-28, wherein, the conditional reconfiguration and the indication to perform the mobility procedure are comprised in the same RRC reconfiguration message.

31. The wireless device (22) of claim 30, wherein, the explicit indication indicates to the wireless device (22) that the conditional reconfiguration comprised in the same RRC reconfiguration message is performed only after accessing the target cell according to the mobility procedure indicated in the same RRC reconfiguration message.

32. The wireless device (22) of claim 25, wherein, the conditional reconfiguration and the indication to perform the mobility procedure are comprised in the same RRC reconfiguration message.

33. The wireless device (22) of claim 25, wherein, the processing circuitry (84) is further configured to cause the wireless device (22) to: perform an RRC re-establishment procedure instead of the indicated mobility procedure and the conditional reconfiguration when the conditional reconfiguration and the indication to perform the mobility procedure are comprised in the same RRC reconfiguration message.

34. The wireless device (22) of any one of claims 25-28, wherein, The mobility procedure is a handover of the wireless device (22) from the source cell to the target cell.

35. The wireless device (22) of any one of claims 25-28, wherein, The mobility procedure corresponds to at least one of a request to add and change a primary secondary cell, PSCell, for the wireless device (22).

36. The wireless device (22) of any one of claims 25-28, wherein, The indication to perform the mobility procedure includes one of a synchronization reconfiguration field and a mobility control information field included in the at least one RRC reconfiguration message.

37. The wireless device (22) of any one of claims 25-28, wherein, The processing circuitry (84) is further configured to cause the wireless device (22) to: receive signaling indicating one of an addition, a modification, and a release of the conditional reconfiguration of the target candidate cell prepared by the target network node (16b).

38. The wireless device (22) of any one of claims 25-28, wherein, The conditional reconfiguration associated with the target candidate cell includes a trigger condition configuration including a set of pointers to at least one measurement identifier, and each measurement identifier of the at least one measurement identifier is associated with at least one trigger condition and an RRC reconfiguration.

39. The wireless device (22) of any one of claims 25-28, wherein, The processing circuitry (84) is further configured to cause the wireless device (22) to: determine not to send an RRC reconfiguration complete message based at least in part on the presence of the conditional reconfiguration associated with the target candidate cell in the at least one RRC reconfiguration message.

40. A network node (16b) comprising processing circuitry (68) configured to cause the network node (16b) to: receive a request to perform a mobility procedure for a wireless device (22) from a source cell supported by a source network node (16a) to a target cell supported by the network node (16b), the request including a current configuration for the wireless device (22) in the source cell; determine, upon receiving the request, to prepare a conditional reconfiguration for the wireless device (22); and send the conditional reconfiguration for the wireless device (22) and a radio resource control, RRC, reconfiguration, the RRC reconfiguration associated with the requested mobility procedure from the source cell to the target cell supported by the network node (16b), and the conditional reconfiguration associated with a target candidate cell determined by the network node (16b); wherein, the target candidate cell associated with the conditional reconfiguration is selectable by the wireless device (22) for a handover of the wireless device (22) to the target candidate cell upon a failure to access the target cell indicated in the requested mobility procedure; wherein an explicit indication indicates to the wireless device (22) that the candidate cell is selected from a first plurality of candidate cells associated with the source network node (16a) supporting the source cell as a result of a failure to attempt to access the target cell, or the candidate cell is selected from the first plurality of candidate cells associated with the network node (16a) supporting the source cell and a second plurality of candidate cells associated with the network node (16b).

41. The network node (16b) of claim 40, wherein, Upon accessing the target cell indicated in the requested mobility procedure, the wireless device (22) is to use the conditional reconfiguration.

42. The network node (16b) of claim 40, wherein, The target candidate cell associated with the conditional reconfiguration is not selectable by the wireless device (22) for handover of the wireless device (22) to the target candidate cell upon failure to access the target cell indicated in the requested mobility procedure.

43. The network node (16b) of any of claims 40-42, wherein, The mobility procedure is a handover of the wireless device (22) from the source cell to the target cell.

44. The network node (16b) of any of claims 40-42, wherein, The mobility procedure corresponds to at least one of a request to add and change a primary secondary cell, PSCell, for the wireless device (22).

45. The network node (16b) of any of claims 40-42, wherein, The processing circuitry (68) is configured to cause the network node (16b) to determine the conditional reconfiguration for the wireless device (22) based at least in part on measurements from the wireless device (22) included in the received request to perform the mobility procedure.

46. The network node (16b) of any of Claims 40-42, wherein, The processing circuitry (68) is configured to cause the network node (16b) to prepare the conditional reconfiguration for the wireless device (22) by being configured to cause the network node (16b) to: send the RRC reconfiguration for the wireless device (22) to a target candidate network node (16c) supporting the target candidate cell; and obtain the conditional reconfiguration from the target candidate network node (16c), the conditional reconfiguration being based at least in part on the sent RRC reconfiguration.

47. The network node (16b) of any of Claims 40-42, wherein, At least one of the conditional reconfiguration associated with the target candidate cell and the RRC reconfiguration associated with the target cell of the mobility procedure is based at least in part on the received current configuration for the wireless device (22) in the source cell.

48. The network node (16b) of any of Claims 40-42, wherein, The processing circuitry (68) is further configured to cause the network node (16b) to: receive an RRC reconfiguration complete message; and as a result of the received RRC reconfiguration complete message, communicate with the wireless device (22) based on an assumption that the wireless device (22) is operating according to the conditional reconfiguration.

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