Patent ID: 12256453

DETAILED DESCRIPTION

Using an enhanced version of the RRCReconfiguration to configure CHO may mean that a field/IE (information element) is included with an AddMod/Release structure for CHO. However, the same message could also be used by the network to trigger a handover, where one needs to include a reconfiguration with sync with information associated to the target cell. A use case that was not foreseen by existing considerations is if a target cell in a handover wants to prepare CHO configurations. If the state-of-the-art specifications are followed, and an implementation of current agreements is assumed this may be performed as shown for example inFIG.3, which is summarized below:1. WD sends measurement report to source NN;2. Source network node processes measurement reports and decides to HO the WD to a target cell supported by the target network node;3. 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;4. Target network node prepares and sends a first RRC reconfiguration in a container for the WD, to be transmitted via source network node;5. WD receives the RRC reconfiguration with reconfiguration with sync from the source network node;6. WD accesses the target cell and sends an RRC reconfiguration complete message to the target network node;7. After accessing the target cell, the target network node can now send another, second RRC reconfiguration to the WD including the CHO configurations prepared by/corresponding to the target network node, and possibly associated measurement configurations; and8. WD can now start performing monitoring of the CHO trigger conditions; and9. WD then sends another, second RRC reconfiguration complete message to the target network node.

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, such as a 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 configurations in a new message to that WD, which increases signaling. Also, that new message may need to include measurement configurations associated to the CHO, which postpones the timing for the WD start to perform measurements for the CHO.

Some embodiments of the present disclosure include a method performed by a wireless device (also called a User Equipment—UE) for a reconfiguration procedure, the method including one or more of:Receiving a message (e.g., a RRCReconfiguration) that includes:conditional reconfigurations (e.g., CHO configurations) associated with corresponding target candidate cells, the conditional reconfigurations being prepared by a target cell/target network node (each conditional reconfiguration may include a triggering condition, an associated RRC reconfiguration to be used by the wireless device upon the triggering condition and a target candidate cell identifier identifying the target candidate cell);indication that the WD may perform a mobility procedure (e.g., a reconfiguration with sync in the RRCReconfiguration message indicating to the WD to perform a handover of the WD from the source cell to the target cell). That indication may be the presence of a reconfiguration with sync field within the CellGroupConfig;Upon receiving the message,The WD first executes the mobility procedure i.e., the WD accesses the target cell indicated in the mobility procedure indication (e.g., HO command/request, such as reconfiguration with sync), instead of the conditional reconfiguration (e.g., CHO configuration) procedure;Only after accessing the target cell does the WD perform the conditional reconfiguration (e.g., CHO configuration) according to the configuration (e.g., RRC reconfiguration) provided in the received message, and starts the actions upon the conditional reconfiguration (e.g., evaluating/monitoring the triggering condition(s) and/or performing a conditional handover of the WD to the target candidate cell upon the triggering condition(s) being met); and/orIn case of failure in performing the mobility procedure (e.g., failure in executing the reconfiguration with Sync):Use any of the configured CHO cells as a chosen/selected cell in the following re-establishment procedure, either the earlier configured CHO target cells (e.g., prepared or determined by a source NN supporting the source cell) or the CHO target candidate cells received in the message (e.g., Reconfiguration with Sync message), and perform a handover of the wireless device to the selected cell instead of a re-establishment.

Some embodiments of the present disclosure include a method performed by a target network node (also called a target gNodeB) for a reconfiguration procedure including conditional reconfigurations (e.g., CHO configurations), the method including one or more of:Receiving from a source network node (e.g. in a handover preparation procedure) the WD's current configuration (i.e., configuration being used in the source cell) in a handover/reconfiguration with sync/PSCell change request message; that message may include measurements performed and reported by the WD e.g., in the inter-node RRM container;Determining to prepare one or more conditional reconfigurations (e.g., configure CHO) for that incoming WD; hence, including the conditional reconfigurations in the WD's target configuration according to the target NN to be provided to the WD by the source NN; this is what is may be included in an RRC container from sent from the target NN to the source NN in the HO preparation procedure;That decision to include conditional reconfigurations corresponding to (i.e., prepared by) the target network node may possibly be determined by the target network node based on e.g., measurements from the WD included in the inter-node message from the source network node in the HO command/request, as described above.If the target candidate cells for the conditional reconfigurations (e.g., CHO configurations) 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 a conditional reconfiguration preparation procedure (which may be a HO preparation procedure with an indication that this is for CHO) with the NNs supporting the target candidate cells by sending e.g., a target WD configuration i.e., the WD configuration that is going to be used in the target cell after the WD accesses it. For that purpose, the target network node (e.g., target gNodeB) may create a WD's full configuration, based on the WD's current configuration in the source cell and what the target network node wants to modify, so that each NN supporting a target candidate cell understands what kind of reconfiguration is requested to prepare for these conditional reconfigurations.In another alternative, only full-configuration is allowed to be prepared by the NNs supporting the target candidate cells in HO.Transmitting to the source network node (e.g., in a handover preparation procedure acknowledgment (ACK) message) the WD's configuration (e.g., container with an RRCReconfiguration containing a reconfiguration with sync and the conditional reconfiguration) to be used in the target cell upon handover execution, including the conditional reconfigurations. Each conditional reconfiguration is per target candidate cell and may include a trigger condition configuration (which may be one or multiple measurement identities associated to a measurement configuration) and a configuration associated with the target candidate cell (which may be an RRCReconfiguration, either full-configuration or delta-configuration having as a baseline the WD's target configuration to be used after the WD accesses the target cell).Receiving an RRCReconfigurationComplete message from that incoming WD (where the WD uses the configuration associated with the target candidate cell) and understanding that the incoming WD is performing actions according to the provided conditional reconfiguration such as the monitoring of triggering conditions that have been configured.

Some embodiments advantageously provide that, by adding conditional reconfiguration (e.g., CHO configuration) in an RRCReconfiguration including a HO command to a given target cell (i.e., also including in the RRCReconfiguration a reconfiguration with sync/HO command/PSCell change command), the amount of signaling used to configure a CHO may be reduced e.g., in the case that the target cell for an incoming WD is capable of conditional reconfiguration (e.g., CHO) and wants to configure CHO for its WDs. In addition to signaling benefits some embodiments also reduce the delay to make the conditional reconfigurations available to WDs, which may reduce the chances of mobility failures.

Some embodiments may also solve ambiguities if both configurations (i.e., both the conditional reconfiguration associated with the target cell/target network node and the RRC reconfiguration associated with the mobility procedure from the source to target cell) (e.g., CHO related fields/information elements (IEs) and HO/Reconfiguration with sync/PSCell change/addition related fields/IEs) are signaled in the same message e.g., an RRCReconfiguration message. For example, in some embodiments, when both configurations are included, the WD may be aware that the RRCReconfigurationmessage is an HO command that includes conditional (e.g., CHO) reconfigurations prepared by the target network node, i.e., the WD may access the target cell and then operate according to the conditional reconfigurations (e.g., configure CHO), instead of the other way around, which could create issues in cases where, for example, the WD first applies CHO configuration and having available measurements CHO execution is triggered and it becomes unclear which HO the WD executes).

In some embodiments, there may be an explicit indication so that the WD does not start to apply the conditional reconfigurations (i.e., start monitoring conditions) upon reception of the RRCReconfiguration message, but only upon accessing the target cell indicated in the RRCReconfiguration message. In some embodiments, this behavior may be predefined in e.g., a standards document.

Another benefit of some embodiments may be the fact that the method works regardless of if the source network node is capable or not of conditional reconfiguration. In other words, the WD may be capable of conditional reconfiguration, the target network node may be capable of conditional reconfiguration, and upon HO configure the WD with the conditional reconfiguration. In some embodiments, this may be transparent to the source NN. Alternatively, if the WD has conditional reconfigurations in the source cell, delta signaling from target NN to source NN for the conditional reconfiguration may be supported to further reduce conditional reconfigurations.

Another benefit of some embodiments is that in case the mobility procedure, such as handover (reconfiguration with sync) fails, the WD has more cells that it can choose from in the following re-configuration procedure and possibly perform a handover instead of a re-establishment. There may also be an explicit indication if the WD is allowed to use only the target cells received from source, only the target cells received from target, or both.

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to conditional handover in handover command. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may 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.

In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections.

The term “network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (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), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The WD herein can be any type of wireless device capable of communicating with a network node or another WD over radio signals, such as wireless device (WD). The WD may 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, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device etc.

Also, in some embodiments the generic term “radio network node” is used. It can be any kind of a radio network node which may comprise any of 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).

In some embodiments, the terms “conditional reconfiguration,” “CHO configuration,” “conditional handover related configuration,” “configuration of a conditional handover,” “conditional reconfiguration with sync,” “RRC connection reconfiguration with mobility control information”, “conditional reconfiguration,” and “conditional RRC Reconfiguration” may be used herein interchangeably.

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

Similarly, in some embodiments, the terms “source” or “target” or “candidate” are used and may be a shortened form of the terms “source node/cell”, “target network node/cell” or “candidate node/cell”, respectively.

In some embodiments, the terms “target node” and “target network node” are used interchangeably.

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

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

It may be considered for cellular communication there is provided 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, e.g., via and/or defining a cell, which may be provided by a network node, in particular a base station or eNodeB or gNB. An uplink direction may refer to a data transfer direction from a terminal to a network node, e.g., base station and/or relay station. A downlink direction may refer to a data transfer direction from a network node, e.g., base station and/or relay node, to a terminal. UL and DL may be associated to different frequency resources, e.g., carriers and/or spectral bands. A cell may comprise at least one uplink carrier and at least one downlink carrier, which may have different frequency bands. A network node, e.g., a base station or eNodeB or gNB, may be adapted to provide and/or define and/or control one or more cells, e.g., a PCell and/or a LA cell.

Any two or more embodiments described in this disclosure may be combined in any way with each other.

The term “signaling” used herein may comprise any of: high-layer signaling (e.g., via Radio Resource Control (RRC) or a like), lower-layer signaling (e.g., via a physical control channel or a broadcast channel), or a combination thereof. The signaling may be implicit or explicit. The signaling may further be unicast, multicast or broadcast. The signaling may also be directly to another node or via a third node.

The term “radio measurement” used herein may refer to any measurement performed on radio signals. Radio measurements can be absolute or relative. Radio measurement may be called as signal level which may be signal quality and/or signal strength. Radio measurements can be e.g. intra-frequency, inter-frequency, inter-RAT measurements, CA measurements, etc. Radio measurements can be unidirectional (e.g., DL or UL) or bidirectional (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 Signals Received Power (RSRP), received signal quality, Reference Signals Received Quality (RSRQ), Signal-to-interference-plus-noise Ratio (SINR), Signal Noise Ratio (SNR), interference power, total interference plus noise, Received Signal Strength Indicator (RSSI), noise power, etc.), cell detection or cell identification, radio link monitoring (RLM), system information (SI) reading, etc. The inter-frequency and inter-RAT measurements are carried out by the WD in measurement gaps unless the WD is capable of doing such measurement without gaps. Examples of measurement gaps are measurement gap id #0 (each gap of 6 ms occurring every 40 ms), measurement gap id #1 (each gap of 6 ms occurring every 80 ms), etc. The measurement gaps are configured at the WD by the network node.

In some embodiments, information on one or more resources may be considered to be transmitted in a message having a specific format. A message may comprise or represent bits representing payload information and coding bits, e.g., for error coding.

Receiving (or obtaining) information may comprise receiving one or more information messages (e.g., RRC reconfiguration). It may be considered that receiving control signaling comprises demodulating and/or decoding and/or detecting, e.g. blind detection of, one or more messages, in particular a message carried by the signaling, e.g. based on an assumed set of resources, which may be searched and/or listened for the information. It may be assumed that both sides of the communication are aware of the configurations, and may determine the set of resources, e.g. based on the reference size.

Signaling may generally comprise one or more symbols and/or signals and/or messages. A signal may comprise or represent one or more bits. An indication may represent signaling, and/or be implemented as a signal, or as a plurality of signals. One or more signals may be included in and/or represented by a message. Signaling, in particular control signaling, may comprise a plurality of signals and/or messages, which may be transmitted on different carriers and/or be associated to different signaling processes, e.g. representing and/or pertaining to one or more such processes and/or corresponding information. An indication may comprise signaling, and/or a plurality of signals and/or messages and/or may be comprised therein, which may be transmitted on different carriers and/or be associated to different acknowledgement signaling processes, e.g. representing and/or pertaining to one or more such processes. Signaling associated to a channel may be transmitted such that represents signaling and/or information for that channel, and/or that the signaling is interpreted by the transmitter and/or receiver to belong to that channel. Such signaling may generally comply with transmission parameters and/or format/s for the channel.

An indication generally may explicitly and/or implicitly indicate the information it represents and/or indicates. Implicit indication may for example be based on position and/or resource used for transmission. Explicit indication may for example be based on a parametrization with one or more parameters, and/or one or more index or indices corresponding to a table, and/or one or more bit patterns representing the information.

Configuring a Radio Node

Configuring a radio node, in particular a terminal or user equipment or the WD, may refer to the radio node being adapted or caused or set and/or instructed to operate according to the configuration. Configuring may be done by another device, e.g., a network node (for example, a radio node of the network like a base station or eNodeB) or network, in which case it may comprise transmitting configuration data to the radio node to be configured. Such configuration data may represent the configuration to be configured and/or comprise one or more instruction pertaining to a configuration, e.g. a configuration for transmitting and/or receiving on allocated resources, in particular frequency resources, or e.g., configuration for performing certain measurements on certain subframes or radio resources. A radio node may configure itself, e.g., based on configuration data received from a network or network node. A network node may use, and/or be adapted to use, its circuitry/ies for configuring. Allocation information may be considered a form of configuration data. Configuration data may comprise and/or be represented by configuration information, and/or one or more corresponding indications and/or message/s.

Configuring in General

Generally, configuring may include determining configuration data representing the configuration and providing, e.g. transmitting, it to one or more other nodes (parallel and/or sequentially), which may transmit it further to the radio node (or another node, which may be repeated until it reaches the wireless device). Alternatively, or additionally, configuring a radio node, e.g., by a network node or other device, may include receiving configuration data and/or data pertaining to configuration data, e.g., from another node like a network node, which may be a higher-level node of the network, and/or transmitting received configuration data to the radio node. Accordingly, determining a configuration and transmitting the configuration data to the radio node may be performed by different network nodes or entities, which may be able to communicate via a suitable interface, e.g., an X2 interface in the case of LTE or a corresponding interface for NR. Configuring a terminal (e.g. WD) may 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 a resource pool therefor. In particular, configuring a terminal (e.g. WD) may comprise configuring the WD to perform certain measurements on certain subframes or radio resources and reporting such measurements according to embodiments of the present disclosure.

Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR), may 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 without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure.

Note further, that functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and/or network nodes. In other words, it is contemplated that the functions of the network node and wireless device described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

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.

Some embodiments provide arrangements for conditional handover in handover command.

Referring again to the drawing figures, in which like elements are referred to by like reference numerals, there is shown inFIG.4a schematic diagram of a communication system10, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and/or NR (5G), which comprises an access network12, such as a radio access network, and a core network14. The access network12comprises a plurality of network nodes16a,16b,16c(referred to collectively as network nodes16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area18a,18b,18c(referred to collectively as coverage areas18). Each network node16a,16b,16cis connectable to the core network14over a wired or wireless connection20. A first wireless device (WD)22alocated in coverage area18ais configured to wirelessly connect to, or be paged by, the corresponding network node16a. A second WD22bin coverage area18bis wirelessly connectable to the corresponding network node16b. While a plurality of WDs22a,22b(collectively referred to as wireless devices22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node16. Note that although only two WDs22and three network nodes16are shown for convenience, the communication system may include many more WDs22and network nodes16.

Also, it is contemplated that a WD22can be in simultaneous communication and/or configured to separately communicate with more than one network node16and more than one type of network node16. For example, a WD22can have dual connectivity with a network node16that supports LTE and the same or a different network node16that supports NR. As an example, WD22can be in communication with an eNB for LTE/E-UTRAN and a gNB for NR/NG-RAN.

The communication system10may itself be connected to a host computer24, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer24may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections26,28between the communication system10and the host computer24may extend directly from the core network14to the host computer24or may extend via an optional intermediate network30. The intermediate network30may be one of, or a combination of more than one of, a public, private or hosted network. The intermediate network30, if any, may be a backbone network or the Internet. In some embodiments, the intermediate network30may comprise two or more sub-networks (not shown).

The communication system ofFIG.4as a whole enables connectivity between one of the connected WDs22a,22band the host computer24. The connectivity may be described as an over-the-top (OTT) connection. The host computer24and the connected WDs22a,22bare configured to communicate data and/or signaling via the OTT connection, using the access network12, the core network14, any intermediate network30and possible further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that at least some of the participating communication devices through which the OTT connection passes are unaware of routing of uplink and downlink communications. For example, a network node16may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer24to be forwarded (e.g., handed over) to a connected WD22a. Similarly, the network node16need not be aware of the future routing of an outgoing uplink communication originating from the WD22atowards the host computer24.

A network node16is configured to include a configuration unit32which is configured to cause the network node16to 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 for the wireless device in the source cell; upon receiving the request, determine to prepare 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 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. In some embodiments, the configuration unit32may be configured to cause the network node16to one or more of: receive a handover (HO) preparation message from a source network node in an HO procedure, the HO preparation message including a current configuration of the WD in a source cell; determine to configure a conditional handover (CHO) for the WD; and transmit a message to the source node, the message including the determined CHO configuration.

A wireless device22is configured to include a handover unit34which is configured to cause the wireless device22to 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 is to perform a mobility procedure, the indication to perform the mobility procedure indicating to perform the mobility procedure from a source cell supported by the 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 handover unit34is configured to cause the wireless device22to receive a message, the message being a radio resource control (RRC) reconfiguration message that includes 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 node; responsive 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 the CHO according to the CHO configuration in the received message.

Example implementations, in accordance with an embodiment, of the WD22, network node16and host computer24discussed in the preceding paragraphs will now be described with reference toFIG.2. In a communication system10, a host computer24comprises hardware (HW)38including a communication interface40configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system10. The host computer24further comprises processing circuitry42, which may have storage and/or processing capabilities. The processing circuitry42may include a processor44and memory46. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry42may comprise integrated circuitry for processing and/or control, e.g., 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. The processor44may be configured to access (e.g., write to and/or read from) memory46, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Processing circuitry42may 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 host computer24. Processor44corresponds to one or more processors44for performing host computer24functions described herein. The host computer24includes memory46that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software48and/or the host application50may include instructions that, when executed by the processor44and/or processing circuitry42, causes the processor44and/or processing circuitry42to perform the processes described herein with respect to host computer24. The instructions may be software associated with the host computer24.

The software48may be executable by the processing circuitry42. The software48includes a host application50. The host application50may be operable to provide a service to a remote user, such as a WD22connecting via an OTT connection52terminating at the WD22and the host computer24. In providing the service to the remote user, the host application50may provide user data which is transmitted using the OTT connection52. The “user data” may be data and information described herein as implementing the described functionality. In one embodiment, the host computer24may be configured for providing control and functionality to a service provider and may be operated by the service provider or on behalf of the service provider. The processing circuitry42of the host computer24may enable the host computer24to observe, monitor, control, transmit to and/or receive from the network node16and/or the wireless device22. The processing circuitry42of the host computer24may include a monitor unit54configured to enable the service provider to observe, monitor, control, transmit to and/or receive from the network node16and/or the wireless device22.

The communication system10further includes a network node16provided in a communication system10and including hardware58enabling it to communicate with the host computer24and with the WD22. The hardware58may include a communication interface60for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system10, as well as a radio interface62for setting up and maintaining at least a wireless connection64with a WD22located in a coverage area18served by the network node16. The radio interface62may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The communication interface60may be configured to facilitate a connection66to the host computer24. The connection66may be direct or it may pass through a core network14of the communication system10and/or through one or more intermediate networks30outside the communication system10.

In the embodiment shown, the hardware58of the network node16further includes processing circuitry68. The processing circuitry68may include a processor70and a memory72. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry68may comprise integrated circuitry for processing and/or control, e.g., 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. The processor70may be configured to access (e.g., write to and/or read from) the memory72, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the network node16further has software74stored internally in, for example, memory72, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node16via an external connection. The software74may be executable by the processing circuitry68. The processing circuitry68may 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 network node16. Processor70corresponds to one or more processors70for performing network node16functions described herein. The memory72is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software74may include instructions that, when executed by the processor70and/or processing circuitry68, causes the processor70and/or processing circuitry68to perform the processes described herein with respect to network node16. For example, processing circuitry68of the network node16may include configuration unit32configured to perform network node methods discussed herein, such as the methods discussed with reference toFIG.10as well as other figures.

The communication system10further includes the WD22already referred to. The WD22may have hardware80that may include a radio interface82configured to set up and maintain a wireless connection64with a network node16serving a coverage area18in which the WD22is currently located. The radio interface82may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers.

The hardware80of the WD22further includes processing circuitry84. The processing circuitry84may include a processor86and memory88. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry84may comprise integrated circuitry for processing and/or control, e.g., 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. The processor86may be configured to access (e.g., write to and/or read from) memory88, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the WD22may further comprise software90, which is stored in, for example, memory88at the WD22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the WD22. The software90may be executable by the processing circuitry84. The software90may include a client application92. The client application92may be operable to provide a service to a human or non-human user via the WD22, with the support of the host computer24. In the host computer24, an executing host application50may communicate with the executing client application92via the OTT connection52terminating at the WD22and the host computer24. In providing the service to the user, the client application92may receive request data from the host application50and provide user data in response to the request data. The OTT connection52may transfer both the request data and the user data. The client application92may interact with the user to generate the user data that it provides.

The processing circuitry84may 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 WD22. The processor86corresponds to one or more processors86for performing WD22functions described herein. The WD22includes memory88that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software90and/or the client application92may include instructions that, when executed by the processor86and/or processing circuitry84, causes the processor86and/or processing circuitry84to perform the processes described herein with respect to WD22. For example, the processing circuitry84of the wireless device22may include a handover unit34configured to perform WD methods discussed herein, such as the methods discussed with reference toFIG.11as well as other figures.

In some embodiments, the inner workings of the network node16, WD22, and host computer24may be as shown inFIG.5and independently, the surrounding network topology may be that ofFIG.4.

InFIG.5, the OTT connection52has been drawn abstractly to illustrate the communication between the host computer24and the wireless device22via the network node16, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the WD22or from the service provider operating the host computer24, or both. While the OTT connection52is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

The wireless connection64between the WD22and the network node16is 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 WD22using the OTT connection52, in which the wireless connection64may form the last segment. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc.

In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection52between the host computer24and WD22, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection52may be implemented in the software48of the host computer24or in the software90of the WD22, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection52passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software48,90may compute or estimate the monitored quantities. The reconfiguring of the OTT connection52may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the network node16, and it may be unknown or imperceptible to the network node16. Some such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary WD signaling facilitating the host computer's24measurements of throughput, propagation times, latency and the like. In some embodiments, the measurements may be implemented in that the software48,90causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection52while it monitors propagation times, errors etc.

Thus, in some embodiments, the host computer24includes processing circuitry42configured to provide user data and a communication interface40that is configured to forward the user data to a cellular network for transmission to the WD22. In some embodiments, the cellular network also includes the network node16with a radio interface62. In some embodiments, the network node16is configured to, and/or the network node's16processing circuitry68is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the WD22, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the WD22.

In some embodiments, the host computer24includes processing circuitry42and a communication interface40that is configured to a communication interface40configured to receive user data originating from a transmission from a WD22to a network node16. In some embodiments, the WD22is configured to, and/or comprises a radio interface82and/or processing circuitry84configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the network node16, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the network node16.

AlthoughFIGS.4and5show various “units” such as configuration unit32, and handover unit34as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

FIG.6is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system ofFIGS.4and5, in accordance with one embodiment. The communication system may include a host computer24, a network node16and a WD22, which may be those described with reference toFIG.5. In a first step of the method, the host computer24provides user data (Block S100). In an optional substep of the first step, the host computer24provides the user data by executing a host application, such as, for example, the host application50(Block S102). In a second step, the host computer24initiates a transmission carrying the user data to the WD22(Block S104). In an optional third step, the network node16transmits to the WD22the user data which was carried in the transmission that the host computer24initiated, in accordance with the teachings of the embodiments described throughout this disclosure (Block S106). In an optional fourth step, the WD22executes a client application, such as, for example, the client application92, associated with the host application50executed by the host computer24(Block S108).

FIG.7is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system ofFIG.4, in accordance with one embodiment. The communication system may include a host computer24, a network node16and a WD22, which may be those described with reference toFIGS.4and5. In a first step of the method, the host computer24provides user data (Block S110). In an optional substep (not shown) the host computer24provides the user data by executing a host application, such as, for example, the host application50. In a second step, the host computer24initiates a transmission carrying the user data to the WD22(Block S112). The transmission may pass via the network node16, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD22receives the user data carried in the transmission (Block S114).

FIG.8is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system ofFIG.4, in accordance with one embodiment. The communication system may include a host computer24, a network node16and a WD22, which may be those described with reference toFIGS.4and5. In an optional first step of the method, the WD22receives input data provided by the host computer24(Block S116). In an optional substep of the first step, the WD22executes the client application92, which provides the user data in reaction to the received input data provided by the host computer24(Block S118). Additionally or alternatively, in an optional second step, the WD22provides 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, client application92(Block S122). In providing the user data, the executed client application92may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the WD22may initiate, in an optional third substep, transmission of the user data to the host computer24(Block S124). In a fourth step of the method, the host computer24receives the user data transmitted from the WD22, in accordance with the teachings of the embodiments described throughout this disclosure (Block S126).

FIG.9is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system ofFIG.4, in accordance with one embodiment. The communication system may include a host computer24, a network node16and a WD22, which may be those described with reference toFIGS.4and5. In an optional first step of the method, in accordance with the teachings of the embodiments described throughout this disclosure, the network node16receives user data from the WD22(Block S128). In an optional second step, the network node16initiates transmission of the received user data to the host computer24(Block S130). In a third step, the host computer24receives the user data carried in the transmission initiated by the network node16(Block S132).

FIG.10is a flowchart of an exemplary process in a network node16for conditional handover in handover command according to some embodiments of the present disclosure. One or more Blocks and/or functions and/or methods performed by the network node16may be performed by one or more elements of network node16such as by configuration unit32in processing circuitry68, processor70, communication interface60, radio interface62, etc. according to the example method. The example method includes receiving (Block S134), such as via configuration unit32, processing circuitry68, processor70, communication interface60and/or radio interface62, 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 upon receiving the request, determining (Block S136), such as via configuration unit32, processing circuitry68, processor70, communication interface60and/or radio interface62, to prepare a conditional reconfiguration for the wireless device. The method includes transmitting (Block S138), such as via configuration unit32, processing circuitry68, processor70, communication interface60and/or radio interface62, 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.

In some embodiments, the conditional reconfiguration is to be used by the wireless device after 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 a handover of the wireless device to the target candidate cell upon a failure to access 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 a handover of the wireless device to the target candidate cell upon a failure to access the target cell indicated in the requested mobility procedure.

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 request to at least one of add and change a primary secondary cell, PScell, for the wireless device. In some embodiments, the determining to prepare the conditional reconfiguration for the wireless device is based at least in part on a measurement 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 comprises transmitting, such as via configuration unit32, processing circuitry68, processor70, communication interface60and/or radio interface62, the RRC reconfiguration for the wireless device to a target candidate network node supporting the target candidate cell. The method includes obtaining, such as via configuration unit32, processing circuitry68, processor70, communication interface60and/or radio interface62, the conditional reconfiguration from the target candidate network node, the conditional reconfiguration being based at least in part on the transmitted RRC reconfiguration.

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 the received current configuration for the wireless device in the source cell. In some embodiments, the method further includes receiving, such as via configuration unit32, processing circuitry68, processor70, communication interface60and/or radio interface62, an RRC reconfiguration complete message; and as a result of the received RRC reconfiguration complete message, communicating, such as via radio interface62, with the wireless device based on an assumption that the wireless device is operating according to the conditional reconfiguration.

In some embodiments, the method includes receiving, such as via configuration unit32, processing circuitry68, processor70and/or radio interface62, a handover (HO) preparation message from a source network node in a HO procedure, the HO preparation message including a current configuration of the WD in a source cell. The method includes determining, such as via configuration unit32, processing circuitry68, processor70and/or radio interface62, to configure a conditional handover (CHO) for the WD. The method includes transmitting, such as via configuration unit32, processing circuitry68, processor70and/or radio interface62, 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 WD22; and/or as a result of the received RRC reconfiguration complete message, communicating with the WD22based on an assumption that the WD i22s operating according to the CHO configuration.

FIG.11is a flowchart of an exemplary process in a wireless device22for conditional handover in handover command according to some embodiments of the present disclosure. One or more Blocks and/or functions and/or methods performed by WD22may be performed by one or more elements of WD22such as by HO unit34in processing circuitry84, processor86, radio interface82, etc. The example method includes receiving (Block S140), such as via HO unit34, processing circuitry84, processor86and/or radio interface82, 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 the 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.

In some embodiments, the method further includes upon receiving the at least one RRC reconfiguration message, performing, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, the mobility procedure indicated in the received at least one RRC reconfiguration by attempting to access the target cell. In some embodiments, the method includes as a result of accessing the target cell, performing, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, at least one action according to the conditional reconfiguration comprised in the received at least one RRC reconfiguration. In some embodiments, the method further includes as a result of a failure in the 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, selecting the candidate cell associated with the conditional handover comprises as the result of the failure in the attempt to access the target cell, selecting, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, 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. In some embodiments, selecting the candidate cell associated with the conditional handover comprises as the result of the failure in the attempt to access the target cell, selecting, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, the candidate cell from among at least a plurality of candidate cells, each candidate cell being associated with a respective conditional handover and the network node supporting the source cell.

In some embodiments, an explicit indication indicates to the wireless device to select the candidate cell from among 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 the result of the failure in the attempt to access the target cell. In some embodiments, the conditional reconfiguration and the indication to perform the mobility procedure are both included in a same RRC reconfiguration message. In some embodiments, an explicit indication indicates to the wireless device to perform the conditional reconfiguration comprised in the same RRC reconfiguration message only after accessing the target cell according to the mobility procedure indicated in the same RRC reconfiguration message.

In some embodiments, the conditional reconfiguration and the indication to perform the mobility procedure are prohibited from being in a same RRC reconfiguration message. In some embodiments, the method further includes when the conditional reconfiguration and the indication to perform the mobility procedure are included in a same RRC reconfiguration message, performing, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, an RRC re-establishment procedure, instead of the indicated mobility procedure and the conditional reconfiguration. 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 request to at least one of add and change a primary secondary cell, PScell, for the wireless device. In some embodiments, the indication to perform the mobility procedure includes one of a reconfiguration with sync field and a mobility control information field comprised in the at least one RRC reconfiguration message.

In some embodiments, the method further includes receiving, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, signaling indicating to one of add, modify and release the conditional reconfiguration of the target candidate cell prepared by the target network node. In some embodiments, the conditional reconfiguration associated with the target candidate cell includes a trigger condition configuration, the 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. In some embodiments, the method further includes determining, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, to not transmit a 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.

In some embodiments, the method includes receiving, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, a message. The message may be a radio resource control (RRC) reconfiguration message that includes 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, responsive to the received message, attempting, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, to access the target network node indicated in the HO command. The method includes, as a result of accessing the target network node, performing, such as via HO unit34, processing circuitry84, processor86and/or radio interface82, the CHO according to the CHO configuration in the received message. In some embodiments, the method includes responsive to a HO failure while attempting to access the target network node, selecting a candidate cell indicated in the CHO configuration and perform a handover of the WD to the selected candidate cell.

Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for conditional handover in handover command, which may be implemented by the network node16, wireless device22and/or host computer24.

Introduction

In some embodiments, a WD22configured with a set of conditional reconfigurations (e.g., RRCReconfiguration(s)), for example, as via configuration of CHO may execute a handover (or conditional handover, depending how the procedure will be called in NR RRC specifications) when the condition for the handover is fulfilled. In the context of this disclosure, the disclosure may refer to conditional reconfiguration, CHO configuration, or conditional handover related configuration interchangeably and which may be for a cell, list of cell(s), measurement object(s) or frequencies. In the case of the cell association, they may be for the same radio access technology (RAT), or for a different RAT.

In the context of the method, the “conditional handover related configuration(s)”, also called conditional reconfiguration(s) for a cell may include one or more of at least the following:An RRCReconfiguration-like message (or any message with equivalent content and/or purpose), possibly containing a reconfigurationWithSync IE using NR terminology (defined in 3GPP Technical Specification (TS) 38.331) and prepared by a target network node16. Or, using the E-UTRA terminology, an RRCConnectionReconfiguration with a mobilityControlInfo IE (defined in 3GPP Technical Specification (TS) 36.331);Triggering condition(s) configuration e.g., such as A1-A6 triggering events or B1-B2 inter-RAT triggering events (as defined in 3GPP TS 38.331/3GPP TSA 36.331 in the reportConfig IE) where instead of triggering a measurement report it would trigger a conditional handover. That may be a pointer to a measurement configuration such as a measurement identifier or a list of measurement identifiers. Other conditional handover controlling parameters e.g., timer defining the validity of target candidate resources, etc.

Throughout the disclosure the term “handover” or “reconfiguration with sync” is used herein e.g., with a similar meaning. Hence, a conditional handover may also be called a conditional reconfiguration with sync. In NR terminology, the handovers are typically called an RRCReconfiguration with a reconfigurationWithSync (field containing configuration necessary to execute a handover, such as target information such as frequency, cell identifier, random access configuration, etc.). In E-UTRA terminology, the handovers are typically called an RRCConnectionReconfiguration with a mobilityControlInfo (field containing configuration necessary to execute a handover). Fundamentally, the disclosure is also applicable for other forms of mobility procedure such as a PSCell change, PSCell addition, etc.

In some embodiments, most of the WD22(and network node16) actions defined in the disclosure and network node16configurations are described as being performed in NR or E-UTRA; in other words, the conditional reconfiguration (e.g., configuration of a conditional HO) received in NR for NR cells. However, the techniques, methods and/or principles are also applicable when any of these steps occurs in different RATs, for example:WD22has NR as source and NR as target; target candidates associated to the NR target may be LTE cells or NR cells;WD22has NR as source and LTE as target; target candidates associated to the NR target may be LTE cells or NR cells;WD22has LTE as source and LTE as target; target candidates associated to the NR target may be LTE cells or NR cells; and/orWD22has LTE as source and NR as target; target candidates associated to the NR target may be LTE cells or NR cells.

Further Example Details and Example Signaling Flows of Some Embodiments

The disclosure describes a method performed by a wireless device22(also called a User Equipment—UE) for a reconfiguration procedure. In some embodiments, the method includes:Receiving a message (e.g. a RRCReconfiguration) that includes:conditional reconfigurations (e.g., CHO configurations) prepared by a target network node16supporting a target cell;indication that the WD22may perform a mobility procedure (e.g., Reconfiguration with Sync indicating a handover of the WD22from the source cell to a target cell). That indication may be the presence of a reconfiguration with sync field within the CellGroupConfig.

The following sections may provide examples of how the RRC specification may be modified or specified to provide for one or more of the arrangements proposed in the present disclosure, such as the WD22receiving the message above.

RRC Reconfiguration (Both Conditional Reconfiguration and Reconfiguration with Sync Allowed in a Same RRC Reconfiguration Message)

One example of how that could be implemented in ASN.1 in the RRC specifications is shown below, where the possibility to signal both of these: conditional reconfigurations (e.g., CHO configurations) and a mobility procedure request (e.g., a HO command), is considered.

The RRCReconfiguration message is the command to modify an RRC connection e.g., to a particular cell (e.g., a source cell). It may 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 may also convey a conditional reconfiguration in a container having an RRCReconfiguration to only be applied upon the fulfilment of a trigger condition.Signalling radio bearer: SRB1 or SRB3Radio Link Control—Service Access Point (RLC-SAP): Acknowledgement Mode (AM)Logical channel: dedicated control channel (DCCH)Direction: Network node16to WD22(e.g., UE)

RRCReconfiguration Message

-- ASN1START-- TAG-RRCRECONFIGURATION-STARTRRCReconfiguration ::=SEQUENCE {rrc-TransactionIdentifierRRC-TransactionIdentifier,criticalExtensionsCHOICE {rrcReconfigurationRRCReconfiguration-IEs,criticalExtensionsFutureSEQUENCE { }}}RRCReconfiguration-IEs ::=SEQUENCE {radioBearerConfigRadioBearerConfigOPTIONAL, -- Need MsecondaryCellGroupOCTET STRING (CONTAININGCellGroupConfig)OPTIONAL, -- Need MmeasConfigMeasConfigOPTIONAL, -- Need MlateNonCriticalExtensionOCTET STRINGOPTIONAL,nonCriticalExtensionRRCReconfiguration-v1530-IEsOPTIONAL}RRCReconfiguration-v1530-IEs ::=SEQUENCE {masterCellGroupOCTET STRING (CONTAININGCellGroupConfig)OPTIONAL, -- Need MfullConfigENUMERATED {true}OPTIONAL, -- Cond FullConfigdedicatedNAS-MessageListSEQUENCE (SIZE(1..maxDRB)) OFDedicatedNAS-MessageOPTIONAL, -- Cond nonHOmasterKeyUpdateMasterKeyUpdateOPTIONAL, -- Cond MasterKeyChangededicatedSIB1-DeliveryOCTET STRING (CONTAINING SIB1)OPTIONAL, -- Need NdedicatedSystemInformationDeliveryOCTET STRING (CONTAININGSystemInformation)OPTIONAL, -- Need NotherConfigOtherConfigOPTIONAL, -- Need MnonCriticalExtensionRRCReconfiguration-v1540-IEsOPTIONAL}RRCReconfiguration-v1540-IEs ::=SEQUENCE {otherConfig-v1540OtherConfig-v1540OPTIONAL, -- Need MnonCriticalExtensionRRCReconfiguration-v1560-IEsOPTIONAL}RRCReconfiguration-v1560-IEs ::=SEQUENCE {mrdc-SecondaryCellGroupConfigSetupRelease { MRDC-SecondaryCellGroupConfig }OPTIONAL, -- Need MradioBearerConfig2OCTET STRING (CONTAININGRadioBearerConfig)OPTIONAL, -- Need Msk-CounterSK-CounterOPTIONAL, -- Need NnonCriticalExtensionRRCReconfiguration-v16-IEsOPTIONAL}RRCReconfiguration-v16-IEs ::=SEQUENCE {conditionalReconfigurationConditionalReconfigurationOPTIONAL, -- Need MnonCriticalExtensionSEQUENCE { } OPTIONAL}MasterKeyUpdate ::=SEQUENCE {keySetChangeIndicatorBOOLEAN,nextHopChainingCountNextHopChainingCount,nas-ContainerOCTET STRINGOPTIONAL, -- Cond securityNASC...}MRDC-SecondaryCellGroupConfig ::=SEQUENCE {mrdc-ReleaseAndAddENUMERATED {true}OPTIONAL, -- Need Nmrdc-SecondaryCellGroupCHOICE {nr-SCGOCTET STRING (CONTAININGRRCReconfiguration),eutra-SCGOCTET STRING}}-- TAG-RRCRECONFIGURATION-STOP-- ASN1STOP

RRCReconfiguration-IEs field descriptionsconditionalReconfigurationConfiguration of conditional handover i.e., for each target candidate it contains a triggercondition associated to an RRCReconfiguration in an OCTET STRING to be appliedupon the fulfilment of the condition. If the message also includes a reconfiguration withsync in CellGroupConfig (e.g. in masterCellGroup and/or secondaryCellGroup) the WD22 performs the reconfiguration with sync and assumes that theconditionalReconfiguration as a target's configuration i.e. to be used in target.dedicatedNAS-MessageListThis field is used to transfer WD specific NAS layer information between the network and theWD 22. The RRC layer is transparent for each PDU in the list.dedicatedSIB1-DeliveryThis field is used to transfer SIB1 to the WD 22. The field has the same values as thecorresponding configuration in servingCellConfigCommon.dedicatedSystemInformationDeliveryThis field is used to transfer SIB6, SIB7, SIB8 to the WD 22.fullConfigIndicates that the full configuration option is applicable for the RRCReconfiguration messagefor intra-system intra-RAT HO. For inter-RAT HO from E-UTRA to NR, fullConfig indicateswhether or not delta signalling of SDAP/PDCP from source RAT is applicable.keySetChangeIndicatorIndicates whether WD 22 may derive a new KgNB. If reconfigurationWithSync is included,value true indicates that a KgNB key is derived from a KAMF key taken into use through thelatest successful NAS SMC procedure, or N2 handover procedure with KAMF change, asdescribed in 3GPP TS 33.501 for KgNB re-keying. Value false indicates that the new KgNBkey is obtained from the current KgNB key or from the NH as described in TS 33.501.masterCellGroupConfiguration of master cell group.mrdc-ReleaseAndAddThis field indicates that the current SCG configuration is released and a new SCG is added atthe same time.mrdc-SecondaryCellGroupIncludes an RRC message for SCG configuration in NR-DC or NE-DC.For NR-DC (nr-SCG), mrdc-SecondaryCellGroup contains the RRCReconfiguration messageas generated (entirely) by SN gNB. In this version of the specification, the RRC message canonly include fields secondaryCellGroup and measConfig.For NE-DC (eutra-SCG), mrdc-SecondaryCellGroup includes the E-UTRARRCConnectionReconfiguration message as specified in TS 36.331. In this version of thespecification, the E-UTRA RRC message can only include the field scg-Configuration.nas-ContainerThis field is used to transfer WD specific NAS layer information between the network and theUE. The RRC layer is transparent for this field, although it affects activation of AS securityafter inter-system handover to NR. The content is defined in 3GPP TS 24.501.nextHopChainingCountParameter NCC: See TS 33.501otherConfigContains configuration related to other configurations.radioBearerConfigConfiguration of Radio Bearers (DRBs, SRBs) including SDAP/PDCP. In EN-DC this fieldmay only be present if the RRCReconfiguration is transmitted over SRB3.radioBearerConfig2Configuration of Radio Bearers (DRBs, SRBs) including SDAP/PDCP. This field can only beused if the UE supports NR-DC or NE-DC.secondaryCellGroupConfiguration of secondary cell group ((NG)EN-DC or NR-DC). This field is absent when theRRCReconfiguration message is directly transmitted via MCG SRB1 and not within mrdc-secondaryCellGroup.sk-CounterA counter used upon initial configuration of S-KgNB or S-KeNB, as well as upon refresh of S-KgNB or S-KeNB. This field is always included upon initial configuration of an NR SCG orupon configuration of the first RB with keyToUse set to secondary. This field is absent if thereis neither any NR SCG nor any RB with keyToUse set to secondary.Conditional PresenceExplanationnonHOThe field is absent in case of reconfiguration with sync withinNR or to NR; otherwise it is optionally present, need N.securityNASCThis field is mandatory present in case of inter system handover.Otherwise the field is optionally present, need N.MasterKeyChangeThis field is mandatory present in case masterCellGroupincludes ReconfigurationWithSync and RadioBearerConfigincludes SecurityConfig with SecurityAlgorithmConfig,indicating a change of the AS security algorithms associated tothe master key. If ReconfigurationWithSync is included for othercases, this field is optionally present, need N. Otherwise thefield is absent.FullConfigThe field is mandatory present in case of inter-system handoverfrom E-UTRA/EPC to NR. It is optionally present, Need N,during reconfiguration with sync and also in firstreconfiguration after reestablishment; or for intra-systemhandover from E-UTRA/5GC to NR. It is absent otherwise.

In an alternative or additional embodiment, only one of the two fields (e.g., conditional reconfiguration and reconfiguration with sync) can be included in the same message at time e.g., in the RRCReconfiguration. The benefit in this embodiment, at least compared to existing techniques, is that it avoids WD22misbehavior due to ambiguities that could exist if both configurations are included without further specification i.e., that includes the addition of a condition so that it is clear that the CHO cannot be signaled when HO/PSCell change/PScell addition is/are being signaled to the WD22, i.e., when masterCellGroupConfig and/or secondaryCellGroupConfig include reconfiguration with sync. In other words, if both fields are included, the WD22does not apply the message and considers that it is not able to comply with it and perform actions upon e.g., re-establishment. An example of such alternative is shown below:

RRC Reconfiguration (Conditional Reconfiguration and Reconfiguration with Sync Prohibited in a Same RRC Reconfiguration Message)

One example of how that could be implemented in ASN.1 in the RRC specifications is shown below, where the possibility to signal only one of these: conditional reconfigurations (e.g., CHO configurations) and a mobility procedure request (e.g., a HO command), is considered.

The RRC Reconfiguration message is the command to modify an RRC connection. It may convey information for measurement configuration, mobility control, radio resource configuration (including RBs, MAC main configuration and physical channel configuration) and AS security configuration. It may also convey a conditional reconfiguration with a container with an RRCReconfiguration to only be applied upon the fulfilment of a trigger condition.Signalling radio bearer: SRB1 or SRB3RLC-SAP: AMLogical channel: DCCHDirection: Network node16to WD22(e.g., UE)

RRCReconfiguration Message

-- ASN1START-- TAG-RRCRECONFIGURATION-STARTRRCReconfiguration ::=SEQUENCE {rrc-TransactionIdentifierRRC-TransactionIdentifier,criticalExtensionsCHOICE {rrcReconfigurationRRCReconfiguration-IEs,criticalExtensionsFutureSEQUENCE { }}}RRCReconfiguration-IEs ::=SEQUENCE {radioBearerConfigRadioBearerConfigOPTIONAL, -- Need MsecondaryCellGroupOCTET STRING (CONTAININGCellGroupConfig)OPTIONAL, -- Need MmeasConfigMeasConfigOPTIONAL, -- Need MlateNonCriticalExtensionOCTET STRINGOPTIONAL,nonCriticalExtensionRRCReconfiguration-v1530-IEsOPTIONAL}RRCReconfiguration-v1530-IEs ::=SEQUENCE {masterCellGroupOCTET STRING (CONTAININGCellGroupConfig)OPTIONAL, -- Need MfullConfigENUMERATED {true}OPTIONAL, -- Cond FullConfigdedicatedNAS-MessageListSEQUENCE (SIZE(1..maxDRB)) OFDedicatedNAS-MessageOPTIONAL, -- Cond nonHOmasterKeyUpdateMasterKeyUpdateOPTIONAL, -- Cond MasterKeyChangededicatedSIB1-DeliveryOCTET STRING (CONTAINING SIB1)OPTIONAL, -- Need NdedicatedSystemInformationDeliveryOCTET STRING (CONTAININGSystemInformation)OPTIONAL, -- Need NotherConfigOtherConfigOPTIONAL, -- Need MnonCriticalExtensionRRCReconfiguration-v1540-IEsOPTIONAL}RRCReconfiguration-v1540-IEs ::=SEQUENCE {otherConfig-v1540OtherConfig-v1540OPTIONAL, -- Need MnonCriticalExtensionRRCReconfiguration-v1560-IEsOPTIONAL}RRCReconfiguration-v1560-IEs ::=SEQUENCE {mrdc-SecondaryCellGroupConfigSetupRelease { MRDC-SecondaryCellGroupConfig }OPTIONAL, -- Need MradioBearerConfig2OCTET STRING (CONTAININGRadioBearerConfig)OPTIONAL, -- Need Msk-CounterSK-CounterOPTIONAL, -- Need NnonCriticalExtensionRRCReconfiguration-v16-IEsOPTIONAL}RRCReconfiguration-v16-IEs ::=SEQUENCE {conditionalReconfigurationConditionalReconfigurationOPTIONAL, -- Cond nonHO-CHOnonCriticalExtensionSEQUENCE { } OPTIONAL}MasterKeyUpdate ::=SEQUENCE {keySetChangeIndicatorBOOLEAN,nextHopChainingCountNextHopChainingCount,nas-ContainerOCTET STRINGOPTIONAL, -- Cond securityNASC...}MRDC-SecondaryCellGroupConfig ::=SEQUENCE {mrdc-ReleaseAndAddENUMERATED {true}OPTIONAL, -- Need Nmrdc-SecondaryCellGroupCHOICE {nr-SCGOCTET STRING (CONTAININGRRCReconfiguration),eutra-SCGOCTET STRING}}-- TAG-RRCRECONFIGURATION-STOP-- ASN1STOP

RRCReconfiguration-IEs field descriptionsconditionalReconfigurationConfiguration of conditional handover i.e., for each target candidate it contains a triggercondition associated to an RRCReconfiguration in an OCTET STRING to be appliedupon the fulfilment of the condition. This is not configured in case the message carries areconfiguration with sync.dedicatedNAS-MessageListThis field is used to transfer WD specific NAS layer information between the network and theWD 22. The RRC layer is transparent for each PDU in the list.dedicatedSIB1-DeliveryThis field is used to transfer SIB1 to the WD 22. The field has the same values as thecorresponding configuration in servingCellConfigCommon.dedicatedSystemInformationDeliveryThis field is used to transfer SIB6, SIB7, SIB8 to the WD 22.fullConfigIndicates that the full configuration option is applicable for the RRCReconfiguration messagefor intra-system intra-RAT HO. For inter-RAT HO from E-UTRA to NR, fullConfig indicateswhether or not delta signalling of SDAP/PDCP from source RAT is applicable.keySetChangeIndicatorIndicates whether WD 22 may derive a new KgNB. If reconfigurationWithSync is included,value true indicates that a KgNBkey is derived from a KAMFkey taken into use through thelatest successful NAS SMC procedure, or N2 handover procedure with KAMFchange, asdescribed in TS 33.501 for KgNBre-keying. Value false indicates that the new KgNBkey isobtained from the current KgNBkey or from the NH as described in TS 33.501.masterCellGroupConfiguration of master cell group.mrdc-ReleaseAndAddThis field indicates that the current SCG configuration is released and a new SCG is added atthe same time.mrdc-SecondaryCellGroupIncludes an RRC message for SCG configuration in NR-DC or NE-DC.For NR-DC (nr-SCG), mrdc-SecondaryCellGroup contains the RRCReconfiguration messageas generated (entirely) by SN gNB. In this version of the specification, the RRC message canonly include fields secondaryCellGroup and measConfig.For NE-DC (eutra-SCG), mrdc-SecondaryCellGroup includes the E-UTRARRCConnectionReconfiguration message as specified in TS 36.331. In this version of thespecification, the E-UTRA RRC message can only include the field scg-Configuration.nas-ContainerThis field is used to transfer WD specific NAS layer information between the network and theWD 22. The RRC layer is transparent for this field, although it affects activation of ASsecurity after inter-system handover to NR. The content is defined in TS 24.501.nextHopChainingCountParameter NCC: See TS 33.501otherConfigContains configuration related to other configurations.radioBearerConfigConfiguration of Radio Bearers (DRBs, SRBs) including SDAP/PDCP. In EN-DC this fieldmay only be present if the RRCReconfiguration is transmitted over SRB3.radioBearerConfig2Configuration of Radio Bearers (DRBs, SRBs) including SDAP/PDCP. This field can only beused if the WD 22 supports NR-DC or NE-DC.secondaryCellGroupConfiguration of secondary cell group ((NG)EN-DC or NR-DC). This field is absent when theRRCReconfiguration message is directly transmitted via MCG SRB1 and not within mrdc-secondaryCellGroup.sk-CounterA counter used upon initial configuration of S-KgNBor S-KeNB, as well as upon refresh of S-KgNBor S-KeNB. This field is always included upon initial configuration of an NR SCG or uponconfiguration of the first RB with keyToUse set to secondary. This field is absent if there isneither any NR SCG nor any RB with keyToUse set to secondary.Conditional PresenceExplanationnonHOThe field is absent in case of reconfiguration with sync withinNR or to NR; otherwise it is optionally present, need N.securityNASCThis field is mandatory present in case of inter system handover.Otherwise the field is optionally present, need N.MasterKeyChangeThis field is mandatory present in case masterCellGroupincludes ReconfigurationWithSync and RadioBearerConfigincludes SecurityConfig with SecurityAlgorithmConfig,indicating a change of the AS security algorithms associated tothe master key. If ReconfigurationWithSync is included for othercases, this field is optionally present, need N. Otherwise thefield is absent.Cond nonHO-CHOThe field is absent in case of reconfiguration with syncwithin NR or to NR; otherwise it is optionally present, needM.FullConfigThe field is mandatory present in case of inter-system handoverfrom E-UTRA/EPC to NR. It is optionally present, Need N,during reconfiguration with sync and also in firstreconfiguration after reestablishment; or for intra-systemhandover from E-UTRA/5GC to NR. It is absent otherwise.

Having described arrangements for the WD22to receive the message above, in some embodiments, the method implemented in a WD22may include, upon receiving the message, one or more of:WD22first executes the mobility procedure i.e., WD22accesses the target cell indicated in e.g., the HO command/reconfiguration with sync (instead of the conditional reconfiguration, e.g., CHO configuration, procedure); and/orOnly after accessing the target cell does the WD22performs the conditional reconfiguration according to the configuration provided in the message, and start the actions upon conditional reconfiguration.

As an example, in the context of the disclosure, the following ASN.1 structure may be assumed for the conditional reconfiguration (e.g., CHO configuration) within the RRC Reconfiguration message, as shown in the previous step:

Conditional Reconfiguration

The IE ConditionalReconfiguration is used to add, modify or release a conditional handover configuration per target candidate cell.

ConditionalReconfiguration Information Element

-- ASN1START-- TAG-CONDITIONAL-RECONFIG-STARTConditionalReconfiguration ::=SEQUENCE {condReconfigurationToRemoveListCondReconfigurationToRemoveListOPTIONAL, -- Need NcondReconfigurationToAddModListCondReconfigurationToAddModListOPTIONAL, -- Need N...}CondReconfigurationToRemoveList ::=SEQUENCE (SIZE(1..maxNrofCondReconf)) OF CondReconfigurationId-- TAG-CONDITIONAL-RECONFIG-STOP-- ASN1STOP

ConditionalReconfiguration field descriptionscondReconfigurationToAddModListList of conditional reconfigurations to add and/or modify.condReconfigurationToRemoveListList of conditional reconfigurations to remove.
ConditionalReconfigurationId

The IE ConditionalReconfigurationId is used to identify a conditional reconfiguration i.e., linking of trigger conditions and an RRCReconfiguration to be applied upon the fulfilment of the conditions.

ConditionalReconfigurationId Information Element

-- ASN1START-- TAG-CONDRECONFIGURATIONID-STARTCondReconfigurationId ::=INTEGER (1..maxNrofCondReconf)-- TAG-CONDRECONFIGURATIONID-STOP-- ASN1STOPCondReconfigurationToAddModListThe IE CondReconfigurationToAddModList concerns a list of conditionalhandover configurations to add or modify, with for each entry the measId (associatedto the triggering condition configuration) and the associated RRCReconfiguration.CondReconfigurationToAddModList information element-- ASN1START-- TAG-CONDRECONFIGURATIONTOADDMODLIST-STARTCondReconfigurationToAddModList ::=SEQUENCE (SIZE (1..maxNrofCondReconf)) OF CondReconfigurationAddModCondReconfigurationAddMod ::=SEQUENCE {condReconfigurationIdCondReconfigurationId,condReconfigurationPerTargetCandidateCondReconfigurationPerTargetCandidate...}-- TAG-CONDRECONFIGURATIONTOADDMODLIST-START-- ASN1STOP
CondReconfigurationPerTargetCandidate

The IE CondReconfigurationPerTargetCandidate contains a conditional reconfiguration for a target candidate cell including a trigger condition configuration which is a set of pointers to measurement identifiers, each measId with its trigger condition, and an associated RRCReconfiguration in an OCTET STRING to be applied when all conditions associated to the measurement identifiers are fulfilled.

CondReconfigurationPerTargetCandidate Information Element

-- ASN1START-- TAG-CONDRECONFIGURATIONPERTARGETCANDIDATE-STARTCondReconfigurationPerTargetCandidate ::=SEQUENCE {rrcReconfigurationToApplyOCTET STRING(CONTAINING RRCReconfiguration)triggerConditionMeasId,...}-- TAG- CONDRECONFIGURATIONPERTARGETCANDIDATE-STOP-- ASN1STOPNote: For further study (FFS): whether the triggerCondition may refer to a list of measurement identifiers e.g. SEQUENCE (SIZE (1 . . . K)) OF MeasId.

Then, in some embodiments, these previous steps could be modeled in the RRC specifications by moving the conditional reconfigurations (e.g., CHO configurations) to after the execution of a possibly received HO command. Thus, it becomes clear that conditional reconfigurations (e.g., CHO configurations) are associated to (e.g., prepared by) the target cell for which the WD22is performing the handover, as shown below (note particularly the bolded sections below).

5.3.5.3 Reception of an RRCReconfiguration by the WD22

The WD22may perform the following actions upon reception of the RRCReconfiguration or upon applying a stored RRCReconfiguration message upon conditional reconfiguration execution:1>if the RRCReconfiguration is received via other RAT (i.e., inter-RAT handover to NR):2>if the RRCReconfiguration does not include the fullConfig and the WD22is connected to 5GC (i.e., delta signalling during intra 5GC handover):3>re-use the source RAT SDAP and PDCP configurations if available (i.e., current SDAP/PDCP configurations for all RBs from source E-UTRA RAT prior to the reception of the inter-RAT HO RRCReconfiguration message);1>else:2>if the RRCReconfiguration includes the fullConfig:3>perform the full configuration procedure as specified in 5.3.5.11;1>if the RRCReconfiguration includes the masterCellGroup:2>perform the cell group configuration for the received masterCellGroup according to 5.3.5.5;1>if the RRCReconfiguration includes the masterKeyUpdate:2>perform AS security key update procedure as specified in 5.3.5.7;1>if the RRCReconfiguration includes the sk-Counter:2>perform security key update procedure as specified in 5.3.5.7;1>if the RRCReconfiguration includes the secondaryCellGroup:2>perform the cell group configuration for the SCG according to 5.3.5.5;1>if the RRCReconfiguration includes the mrdc-SecondaryCellGroupConfig:2>if the mrdc-SecondaryCellGroupConfig is set to setup:3>if the mrdc-SecondaryCellGroupConfig includes mrdc-ReleaseAndAdd:4>perform MR-DC release as specified in section 5.3.5.10;3>if the received mrdc-SecondaryCellGroup is set to nr-SCG:4>perform the RRC reconfiguration according to 5.3.5.3 for the RRCReconfiguration message included in nr-SCG;3>if the received mrdc-SecondaryCellGroup is set to eutra-SCG:4>perform the RRC connection reconfiguration as specified in TS 36.331, clause 5.3.5.3 for the RRCConnectionReconfiguration message included in eutra-SCG;2>else (mrdc-SecondaryCellGroupConfig is set to release):3>perform MR-DC release as specified in section 5.3.5.10;1>if the RRCReconfiguration message includes the radioBearerConfig:2>perform the radio bearer configuration according to 5.3.5.6;1>if the RRCReconfiguration message includes the radioBearerConfig2:2>perform the radio bearer configuration according to 5.3.5.6;1>if the RRCReconfiguration message includes the measConfig:2>perform the measurement configuration procedure as specified in 5.5.2;1>if the RRCReconfiguration message includes the dedicatedNAS-MessageList:2>forward each element of the dedicatedNAS-MessageList to upper layers in the same order as listed;1>if the RRCReconfiguration message includes the dedicatedSIB1-Delivery:2>perform the action upon reception of SIB1 as specified in 5.2.2.4.2;1>if the RRCReconfiguration message includes the dedicatedSystemInformationDelivery:2>perform the action upon reception of System Information as specified in 5.2.2.4;1>if the RRCReconfiguration message includes the otherConfig:2>perform the other configuration procedure as specified in 5.3.5.9;1>if the RRCReconfiguration message includes the conditionalReconfiguration:2>perform conditional reconfiguration as specified in 5.3.5.x;Note: FFS Confirm the usage of an enhanced version of the RRCReconfiguration message to configure conditional handover.1>set the content of RRCReconfigurationComplete message as follows:Note: FFS Whether to provide an exception to the transmission of the RRCReconfigurationComplete message i.e. not transmit if only conditional reconfiguration is included in the message.Note: FFS Whether to provide an exception to the transmission of the RRCReconfigurationComplete message i.e. not transmit in case the message contains CHO configuration and upon reception a trigger condition is fulfilled.2>if the RRCReconfiguration includes the masterCellGroup containing the reportUplinkTxDirectCurrent; or2>if the RRCReconfiguration includes the secondaryCellGroup containing the reportUplinkTxDirectCurrent:3>include the uplinkTxDirectCurrentList for each serving cell with UL;3>if WD22is configured with SUL carrier:4>include uplinkDirectCurrentBWP-SUL for each serving cell with SUL within the uplinkTxDirectCurrentList;2>if the received RRCReconfiguration message includes the mrdc-SecondaryCellGroupConfig with mrdc-SecondaryCellGroup set to eutra-SCG:3>include eutra-SCG-Response within scg-Response in accordance with TS 36.331 clause 5.3.5.3;2>if the received RRCReconfiguration message includes the mrdc-SecondaryCellGroupConfig with mrdc-SecondaryCellGroup set to nr-SCG:3>include nr-SCG-Response within scg-Response;1>if the WD22is configured with E-UTRA nr-SecondaryCellGroupConfig (MCG is E-UTRA):2>ifRRCReconfiguration was received via SRB1:3>submit the RRCReconfigurationComplete via the E-UTRA MCG embedded in E-UTRA RRC message RRCConnectionReconfigurationComplete as specified in TS 36.331;3>if reconfigurationWithSync was included in spCellConfig of an SCG:4>initiate the Random Access procedure on the SpCell, as specified in TS 38.321;3>else:4>the procedure ends;NOTE 1: The order the WD22sends the RRCConnectionReconfigurationComplete message and performs the Random Access procedure towards the SCG is left to WD implementation.2>else (RRCReconfiguration was received via SRB3):3>submit the RRCReconfigurationComplete message via SRB3 to lower layers for transmission using the new configuration;NOTE 2: In (NG)EN-DC and NR-DC, in the case RRCReconfiguration is received via SRB1, the random access is triggered by RRC layer itself as there is not necessarily other UL transmission. In the case RRCReconfiguration is received via SRB3, the random access is triggered by the MAC layer due to arrival of RRCReconfigurationComplete.1>else if RRCReconfiguration message was received within the nr-SCG within mrdc-SecondaryCellGroup (NR SCG RRC Reconfiguration):2>if reconfigurationWithSync was included in spCellConfig in nr-SCG:3>initiate the Random Access procedure on the PSCell, as specified in TS 38.321;2>else3>the procedure ends;1>else if RRCReconfiguration was received via SRB3:2>submit the RRCReconfigurationComplete message via SRB3 to lower layers for transmission using the new configuration;1>else (MCG RRCReconfiguration):2>submit the RRCReconfigurationComplete message via SRB1 to lower layers for transmission using the new configuration;2>if this is the first RRCReconfiguration message after successful completion of the RRC re-establishment procedure:3>resume SRB2 and DRBs that are suspended;1>if reconfigurationWithSync was included in spCellConfig of an MCG or SCG, and when MAC of an NR cell group successfully completes a Random Access procedure triggered above;2>stop timer T304 for that cell group;2>apply the parts of the CQI reporting configuration, the scheduling request configuration and the sounding RS configuration that do not require the WD22 to know the SFN of the respective target SpCell, if any;2>apply the parts of the measurement and the radio resource configuration that require the WD22to know the SFN of the respective target SpCell (e.g. measurement gaps, periodic CQI reporting, scheduling request configuration, sounding RS configuration), if any, upon acquiring the SFN of that target SpCell;2>if the reconfigurationWithSync was included in spCellConfig of an MCG:3>if T390 is running:4>stop timer T390 for all access categories;4>perform the actions as specified in 5.3.14.4.3>ifRRCReconfiguration does not include dedicatedSIB1-Delivery and3>if the active downlink BWP, which is indicated by the firstActiveDownlinkBWP-Id for the target SpCell of the MCG, has a common search space configured by searchSpaceSlB1:4>acquire the SIB1, which is scheduled as specified in TS 38.213, of the target SpCell of the MCG;4>upon acquiring SIB1, perform the actions specified in clause 5.2.2.4.2;2>remove all the entries within VarConditionalReconfiguration, if any;Note: FFS Whether we need to specify any WD autonomous actions regarding VarMeasConfig associated to conditional handover.Note: FFS Confirm the use of a WD variable to handle CHO configurations e.g. VarConditionalReconfiguration.2>the procedure ends.NOTE 3: The WD22is only required to acquire broadcasted SIB1 if the WD22can acquire it without disrupting unicast data reception, i.e. the broadcast and unicast beams are quasi co-located.
5.3.5.x Conditional Reconfiguration
5.3.5.x.1 General

In some embodiments, the network node16configures the WD22with conditional reconfiguration including per target cell candidate an RRCReconfiguration to only be applied upon the fulfilment of an associated trigger condition configuration. The network node16provides the configuration parameters in the ConditionalReconfiguration IE.

In some embodiments, the WD22performs one or more of the following actions based on a received ConditionalReconfiguration IE:1>if the received condReconfiguration includes the condReconfigurationToRemoveList:2>perform the conditional reconfiguration removal procedure as specified in 5.3.5.x.2;1>if the received condReconfiguration includes the condReconfigurationToAddModList:2>perform the conditional reconfiguration removal addition/modification procedure as specified in 5.3.5.x.3.
5.3.5.x.2 Conditional Reconfiguration Removal

The WD22may:1>for each condReconfigurationId included in the received condReconfigurationToRemoveList that is part of the current WD22configuration in VarConditionalReconfiguration:2>stop the monitoring of triggering conditions linked by the measurement identities;2>remove the entry with the matching condReconfigurationId from the condReconfigurationList within the VarConditionalReconfiguration;NOTE: The WD22does not consider the message as erroneous if the condReconfigurationToRemoveList includes any condReconfigurationId value that is not part of the current WD22configuration.Note: FFS Whether to define any WD autonomous removal of measurement configurations upon the removal of a CHO configuration.
5.3.5.x.3 Conditional Reconfiguration Addition/Modification

The WD22may:1>for each condReconfigurationId included in the received condReconfigurationToAddModList:2>if an entry with the matching condReconfigurationId exists in the condReconfigurationList within the VarConditionalReconfiguration:3>stop the monitoring of triggering conditions linked by the measurement identities;3>replace the entry with the values received for this condReconfigurationId;Note: FFS Confirm that the RRCReconfiguration is also replaced, and handling if that is absent.2>else:3>add a new entry for this condReconfigurationId within the VarConditionalReconfiguration;3>store the associated RRCReconfiguration in VarConditionalReconfiguration;2>monitor the triggering conditions associated to the measurement identities of that condReconfigurationId, as specified in 5.5.4
5.3.5.x.4 Conditional Reconfiguration Execution

For the measId for which the trigger condition for conditional reconfiguration was fulfilled, the WD22may:1>for each condReconfigurationId within the VarConditionalReconfiguration that has that measId associated to its stored RRCReconfiguration:2>if all trigger conditions are fulfilled for that condReconfigurationId:3>consider the target cell candidate within the stored RRCReconfiguration, associated to that condReconfigurationId, as a triggered cell;1>if there are more than one triggered cell:2>FFS;Note: FFS Cell selection in case multiple cells fulfil the triggering conditions for conditional reconfiguration.1>else:2>consider that cell as the selected cell for conditional reconfiguration;1>upon selecting one target candidate cell for conditional reconfiguration:2>if the WD22is able to comply with the stored RRCReconfiguration for the selected cell:3>apply the stored RRCReconfiguration as specified in 5.3.5.3;2>else:3>perform the reconfiguration failure procedure, as specified in 5.3.5.8;Note: FFS Whether the compliance of the target candidates RRCReconfiguration is performed upon reception of the conditional reconfiguration(s).

In some embodiments, a signaling flow focusing on the WD22aspects is shown, for example, inFIG.12. Although the example is described in terms of a HO procedure, the principles may also be applicable to other types of mobility procedures.

FIG.12shows the WD22transmitting an RRC measurement report to the source network node16ain step S142. The source network node16amay then transmit a request to perform a mobility procedure for the WD22, such as by transmitting a HO preparation message including the current WD's22configuration information to the target network node16bin step S144. The target network node16bis capable of CHO and may determine to configure that to the WD22in step S146. The target network node16bmay then send an acknowledgement (ACK) message to the source network node16ain step S148. The ACK message may include a configuration e.g., RRC reconfiguration to be used in a target cell supported by the target network node16b, as well as, the conditional reconfigurations (e.g., CHO configurations) e.g., associated with a target candidate cell corresponding to/prepared by the target network node16b. The source network node16amay transmit the RRC reconfiguration to the WD22in step S150. The RRC reconfiguration may include an indication to perform the mobility procedure (e.g., reconfiguration with synch) as well as the conditional reconfiguration. In some embodiments, the reconfiguration with synch may be considered a HO command and the CHO configuration may be comprised in the conditional reconfiguration. The WD22may then transmit an RRC reconfiguration complete message to the target network node16bin step S152. The WD22may begin performing at least one action according to the conditional reconfiguration, such monitoring of CHO trigger conditions in step S154, as shown for example inFIG.12.

In some embodiments, the disclosure provides for a method performed by a target network node16b(also called a source gNodeB) for reconfiguration procedure including conditional reconfigurations (e.g., CHO configurations), the method including one or more of the following:Receiving from a source node16a(e.g., in a handover preparation procedure) the WD's22current configuration (i.e., configuration being used in a source cell supported by the source network node16a) in a handover/reconfiguration with sync/PSCell change request message; the request message may include measurements performed and reported by the WD22e.g. in the inter-node RRM container;Determining to prepare a conditional reconfiguration for the WD22, such as by configuring CHO for that incoming WD22; hence, including CHO configurations in the WD's22target configuration according to the target network node16b, to be provided to the WD22by the source network node16a; the conditional reconfiguration (e.g., associated with a target candidate cell) and the WD's22target configuration (e.g., RRC reconfiguration to be used by the WD22after accessing the target cell supported by the target network node16b) included in an RRC container from target network node16bto source network node16ain the HO preparation procedure;That decision to include the conditional reconfigurations by target network node16bmay possibly be determined based on measurements from the WD22included in the inter-node message from the source network node16ain the HO request, as described above.If target candidate cells associated with the conditional reconfigurations to be given to the WD22are not supported by the same target network node16b(e.g., cells supported by other neighbor network nodes), the target network node16bmay initiate a CHO preparation procedure (which may be a HO preparation procedure with an indication that this is for CHO) with target candidate network nodes by sending a target WD22configuration i.e., the WD22configuration that is going to be used in the target cell after the WD22accesses it. For that purpose, the target network node16bmay create a WD's22full configuration, based on the WD's22current configuration in the source cell and what the target network node (e.g., network node16b) wants to modify, so that each target candidate network node understands what kind of reconfiguration may be used to prepare for these conditional reconfigurations. In another alternative, only full-configuration is allowed to be prepared by target candidate network nodes associated to a target candidate cell in HO.Transmitting to the source node (e.g., network node16a) (e.g. in a handover preparation procedure, ACK) the WD's22configuration (e.g. container with an RRC reconfiguration containing a reconfiguration with sync and conditional reconfiguration) to be used in the target upon handover execution, including CHO configurations. Each conditional reconfiguration is per target candidate cell and includes a trigger condition configuration (which may be one or multiple measurement identities associated to measurement configuration) and a target candidate cell configuration (which may be an RRC reconfiguration, either full-config or delta configuration having as baseline the WD's22target configuration to be used after the WD22accesses the target cell).Receiving an RRC reconfiguration complete message from that incoming WD22(where WD22uses the WD's22target configuration) and understanding that the incoming WD22is performing actions according to the provided conditional reconfiguration such as the monitoring of triggering conditions that have been configured.

In some embodiments, a signaling flow focusing on an example of the network node16aspects (signaling between source NN16a, target NN16band target candidate NN16cfor CHO) is shown inFIG.13, as an example.FIG.13shows the WD22transmitting an RRC measurement report to the source network node16ain step S156. The source network node16athen transmits an HO preparation message including the current WD's22configuration information to the target network node16bin step S158. The target network node16bis capable of CHO and may determine to prepare a conditional reconfiguration for the WD22, e.g., configure CHO to the WD22in step S160. The target network node16bmay transmit a CHO preparation message to a target candidate network node16cin step S162. The CHO preparation may include the WD's22configuration to be used in the target cell. In step S164, the target candidate network node16cmay send an ACK including a configuration to be eventually used in the target candidate cell, e.g., CHO configurations associated with the target candidate cell.

In step S166, the target network node16bmay then send an acknowledgement (ACK) message to the source network node16a. The ACK message may include a configuration to be used in the target cell, e.g., RRC reconfiguration, in addition to the conditional reconfiguration associated with the target candidate cell from the target candidate network node16c. In step S168, the source network node16amay transmit the RRC reconfiguration to the WD22. The RRC reconfiguration may include a reconfiguration with synch (HO command) as well as the conditional reconfiguration from the target candidate network node16c. In step S170, the WD22may then transmit an RRC reconfiguration complete message to the target network node16b. In step S172, the WD22may begin performing the monitoring of CHO trigger conditions as shown for example inFIG.13.

Generally, in a case where the handover (reconfiguration with synch) fails a re-establishment will occur. It is a working assumption in RAN2 that in case of re-establishment and the WD22chooses a cell which has CHO configured, the WD22is allowed to perform a handover to that cell instead of a re-establishment. In this disclosure, the WD22will possibly be configured both with CHO target cells from the source network node (e.g., network node16a) and CHO target cells from the target network node (e.g., network node16b). Some embodiments of the disclosure describe which cells (e.g., candidate cells) the WD22is allowed to perform handover to. That could be performed either in procedure text, or as an explicit indication where it is indicated that the WD22is allowed to use the CHO target cells from the source network node16a, or the CHO target cells from the target network node16bor both. See below an example of implementation in a procedure text in TS 38.331 marked with bold and underline in the section below:

5.3.5.5 Reception of an RRCReconfiguration by the WD22

The WD22(e.g., UE) may perform the following actions upon reception of the RRCReconfiguration or upon applying a stored RRCReconfiguration message upon conditional reconfiguration execution:1>if the RRCReconfiguration is received via other RAT (i.e., inter-RAT handover to NR):2>if the RRCReconfiguration does not include the fullConfig and the WD22is connected to 5GC (i.e., delta signalling during intra 5GC handover):3>re-use the source RAT SDAP and PDCP configurations if available (i.e., current SDAP/PDCP configurations for all RBs from source E-UTRA RAT prior to the reception of the inter-RAT HO RRCReconfiguration message);1>else:2>if the RRCReconfiguration includes the fullConfig:3>perform the full configuration procedure as specified in 5.3.5.11;1>if the RRCReconfiguration includes the masterCellGroup:2>perform the cell group configuration for the received masterCellGroup according to 5.3.5.5;1>if the RRCReconfiguration includes the masterKeyUpdate:2>perform AS security key update procedure as specified in 5.3.5.7;1>if the RRCReconfiguration includes the sk-Counter:2>perform security key update procedure as specified in 5.3.5.7;1>if the RRCReconfiguration includes the secondaryCellGroup:2>perform the cell group configuration for the SCG according to 5.3.5.5;1>if the RRCReconfiguration includes the mrdc-SecondaryCellGroupConfig:2>if the mrdc-SecondaryCellGroupConfig is set to setup:3>if the mrdc-SecondaryCellGroupConfig includes mrdc-ReleaseAndAdd:4>perform MR-DC release as specified in section 5.3.5.10;3>if the received mrdc-SecondaryCellGroup is set to nr-SCG:4>perform the RRC reconfiguration according to 5.3.5.3 for the RRCReconfiguration message included in nr-SCG;3>if the received mrdc-SecondaryCellGroup is set to eutra-SCG:4>perform the RRC connection reconfiguration as specified in TS 36.331, clause 5.3.5.3 for the RRCConnectionReconfiguration message included in eutra-SCG;2>else (mrdc-SecondaryCellGroupConfig is set to release):3>perform MR-DC release as specified in section 5.3.5.10;1>if the RRCReconfiguration message includes the radioBearerConfig:2>perform the radio bearer configuration according to 5.3.5.6;1>if the RRCReconfiguration message includes the radioBearerConfig2:2>perform the radio bearer configuration according to 5.3.5.6;1>if the RRCReconfiguration message includes the measConfig:2>perform the measurement configuration procedure as specified in 5.5.2;1>if the RRCReconfiguration message includes the dedicatedNAS-MessageList:2>forward each element of the dedicatedNAS-MessageList to upper layers in the same order as listed;1>if the RRCReconfiguration message includes the dedicatedSIB1-Delivery:2>perform the action upon reception of SIB1 as specified in 5.2.2.4.2;1>if the RRCReconfiguration message includes the dedicatedSystemInformationDelivery:2>perform the action upon reception of System Information as specified in 5.2.2.4;1>if the RRCReconfiguration message includes the otherConfig:2>perform the other configuration procedure as specified in 5.3.5.9;1>if the RRCReconfiguration message includes the conditionalReconfiguration:2>perform conditional reconfiguration as specified in 5.3.5.x;Note: FFS Confirm the usage of an enhanced version of the RRCReconfiguration message to configure conditional handover.NOTE: If the RRCReconfigguration message includes both reconfiggurationwithSvnc and conditionalReconfigguration, the WD22may consider all conditional handover target cells in case of failure in the reconfiggurationwithSvnc procedure.1>set the content of RRCReconfigurationComplete message as follows:Note: FFS Whether we need an exception to the transmission of the RRCReconfigurationComplete message i.e. not transmit if only conditional reconfiguration is included in the message.Note: FFS Whether we need an exception to the transmission of the RRCReconfigurationComplete message i.e. not transmit in case the message contains CHO configuration and upon reception a trigger condition is fulfilled.2>if the RRCReconfiguration includes the masterCellGroup containing the reportUplinkTxDirectCurrent; or2>if the RRCReconfiguration includes the secondaryCellGroup containing the reportUplinkTxDirectCurrent:3>include the uplinkTxDirectCurrentList for each serving cell with UL;3>if WD22is configured with SUL carrier:4>include uplinkDirectCurrentBWP-SUL for each serving cell with SUL within the uplinkTxDirectCurrentList;2>if the received RRCReconfiguration message includes the mrdc-SecondaryCellGroupConfig with mrdc-SecondaryCellGroup set to eutra-SCG:3>include eutra-SCG-Response within scg-Response in accordance with TS 36.331 clause 5.3.5.3;2>if the received RRCReconfiguration message includes the mrdc-SecondaryCellGroupConfig with mrdc-SecondaryCellGroup set to nr-SCG:3>include nr-SCG-Response within scg-Response;1>if the WD22is configured with E-UTRA nr-SecondaryCellGroupConfig (MCG is E-UTRA):2>if RRCReconfiguration was received via SRB1:3>submit the RRCReconfigurationComplete via the E-UTRA MCG embedded in E-UTRA RRC message RRCConnectionReconfigurationComplete as specified in TS 36.331;3>if reconfigurationWithSync was included in spCellConfig of an SCG:4>initiate the Random Access procedure on the SpCell, as specified in TS 38.321;3>else:4>the procedure ends;NOTE 1: The order the WD22sends the RRCConnectionReconfigurationComplete message and performs the Random Access procedure towards the SCG is left to WD22implementation.2>else (RRCReconfiguration was received via SRB3):3>submit the RRCReconfigurationComplete message via SRB3 to lower layers for transmission using the new configuration;NOTE 2: In (NG)EN-DC and NR-DC, in the case RRCReconfiguration is received via SRB1, the random access is triggered by RRC layer itself as there is not necessarily other UL transmission. In the case RRCReconfiguration is received via SRB3, the random access is triggered by the MAC layer due to arrival of RRCReconfigurationComplete.1>else if RRCReconfiguration message was received within the nr-SCG within mrdc-SecondaryCellGroup (NR SCG RRC Reconfiguration):2>if reconfigurationWithSync was included in spCellConfig in nr-SCG:3>initiate the Random Access procedure on the PSCell, as specified in TS 38.321;2>else3>the procedure ends;1>else if RRCReconfiguration was received via SRB3:2>submit the RRCReconfigurationComplete message via SRB3 to lower layers for transmission using the new configuration;1>else (MCG RRCReconfiguration):2>submit the RRCReconfigurationComplete message via SRB1 to lower layers for transmission using the new configuration;2>if this is the first RRCReconfiguration message after successful completion of the RRC re-establishment procedure:3>resume SRB2 and DRBs that are suspended;1>if reconfigurationWithSync was included in spCellConfig of an MCG or SCG, and when MAC of an NR cell group successfully completes a Random Access procedure triggered above;2>stop timer T304 for that cell group;2>apply the parts of the CQI reporting configuration, the scheduling request configuration and the sounding RS configuration that do not require the WD22to know the SFN of the respective target SpCell, if any;2>apply the parts of the measurement and the radio resource configuration that require the WD22to know the SFN of the respective target SpCell (e.g. measurement gaps, periodic CQI reporting, scheduling request configuration, sounding RS configuration), if any, upon acquiring the SFN of that target SpCell;2>if the reconfigurationWithSync was included in spCellConfig of an MCG:3>if T390 is running:4>stop timer T390 for all access categories;4>perform the actions as specified in 5.3.14.4.3>ifRRCReconfiguration does not include dedicatedSIB1-Delivery and3>if the active downlink BWP, which is indicated by the firstActiveDownlinkBWP-Id for the target SpCell of the MCG, has a common search space configured by searchSpaceSIB1:4>acquire the SIB1, which is scheduled as specified in TS 38.213, of the target SpCell of the MCG;4>upon acquiring SIB1, perform the actions specified in clause 5.2.2.4.2;2>remove all the entries within VarConditionalReconfiguration, if any;Note: FFS Whether we need to specify any WD autonomous actions regarding VarMeasConfig associated to conditional handover.Note: FFS Confirm the use of a WD variable to handle CHO configurations e.g. VarConditionalReconfiguration.2>the procedure ends.NOTE 3: The WD22may only be required to acquire broadcasted SIB1 if the WD22can acquire it without disrupting unicast data reception, i.e., the broadcast and unicast beams are quasi co-located.

In addition, some embodiments may include one or more of the following:

Embodiment A1. A network node configured to communicate with a wireless device (WD), the network node configured to, and/or comprising a radio interface and/or comprising processing circuitry configured to one or more of:receive a handover (HO) preparation message from a source network node in a HO procedure, the HO preparation message including a current configuration of the WD in a source cell;determine to configure a conditional handover (CHO) for the WD; andtransmit a message to the source network node, the message including the determined CHO configuration.

Embodiment A2. The network node of Embodiment A1, wherein the network node and/or the radio interface and/or the processing circuitry is further configured to:receive a radio resource control (RRC) reconfiguration complete message from the WD; andas a result of the received RRC reconfiguration complete message, communicate with the WD based on an assumption that the WD is operating according to the CHO configuration.

Embodiment B1. A method implemented in a network node, the method comprising one or more of:receiving a handover (HO) preparation message from a source network node in a HO procedure, the HO preparation message including a current configuration of the WD in a source cell;determining to configure a conditional handover (CHO) for the WD; andtransmitting a message to the source network node, the message including the determined CHO configuration.

Embodiment B2. The method of Embodiment B1, further comprising: receiving a radio resource control (RRC) reconfiguration complete message from the WD; andas a result of the received RRC reconfiguration complete message, communicating with the WD based on an assumption that the WD is operating according to the CHO configuration.

Embodiment C1. A wireless device (WD) configured to communicate with a network node, the WD configured to, and/or comprising a radio interface and/or processing circuitry configured to one or more of:receive a message, the message being a radio resource control (RRC) reconfiguration message that includes 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;responsive to the received message, attempt to access the target network node indicated in the HO command; and/oras a result of accessing the target network node, perform the CHO according to the CHO configuration in the received message.

Embodiment C2. The WD of Embodiment C1, wherein the WD and/or the radio interface and/or the processing circuitry is further configured to:responsive to a HO failure while attempting to access the target network node, select a candidate cell indicated in the CHO configuration and perform a handover of the WD to the selected candidate cell.

Embodiment D1. A method implemented in a wireless device (WD), the method comprising one or more of:receiving a message, the message being a radio resource control (RRC) reconfiguration message that includes 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;responsive to the received message, attempting to access the target network node indicated in the HO command; and/oras a result of accessing the target network node, performing the CHO according to the CHO configuration in the received message.

Embodiment D2. The method of Embodiment D1, further comprising:responsive to a HO failure while attempting to access the target network node, selecting a candidate cell indicated in the CHO configuration and perform a handover of the WD to the selected candidate cell.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and/or computer storage media storing an executable computer program. Accordingly, the concepts described herein may 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 may be performed by, and/or associated to, a corresponding module, which may be implemented in software and/or firmware and/or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

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 may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), 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.

These computer program instructions may 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 instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may 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.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Computer program code for carrying out operations of the concepts described herein may 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 may also be written in conventional procedural programming languages, such as the “C” programming language. The program code may 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 may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, may be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and may support claims to any such combination or subcombination.

It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it may be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.