Sharing RRC layer cells

Abstract

A method is disclosed, comprising: sending at least one measurement report to a network entity, the network entity providing a serving cell and a target cell for an apparatus, where the serving cell and the target cell share at least a protocol configuration of a radio resource control layer; receiving, from the network entity, an indication of a handover configuration for a handover of the device to the target cell; a handover is performed according to the handover configuration based on receiving the indication of the handover configuration. Further, a corresponding apparatus is disclosed, as well as a network entity and a core network entity and corresponding methods performed by the network entity and the core network entity.

Description

Technical Field

[0001] The following disclosure relates to the field of communication technology, in particular to communication networks, and in particular to wireless communication networks. The present disclosure may, for example, relate to a device and a network entity that can be used for mobility of distributed unit control. Background Art

[0002] In 5G systems and modern communication technologies, a cell-specific vertical protocol stack structure with Layer 3 (RRC), Layer 2 (PDCP, RLC, MAC) and Layer 1 is generally used. The RRC layer provides all information about the parameters used to configure the other layers (Layer 1, Layer 2). On the UE side, a (same) dual version of the RRC layer is created from the RRC message received by the UE from the network entity. The same protocol stack on the network side and the UE side enables perfect recovery of IP packets. Therefore, when the UE moves to another cell, the RRC layer initiates reconfiguration of different (sub) layers in the entire protocol stack on the network side (for example, the RRC entity migrates to the new cell). The corresponding configuration can be sent to the UE, and the UE must decode each of the configurations for all layers in order to perform the switch.

[0003] Overview of Some Example Embodiments

[0004] Example aspects and embodiments may enable the use of a protocol stack architecture that defines cells at the media access control (MAC) layer rather than the RRC layer, which may enable a cell-free architecture for the PDCP and RLC layers. This may enhance deployments in cloud-native environments, where a central unit is located in the cloud and a distributed unit (DU) is located at the edge of the cloud. Example aspects and embodiments may enable the ability to hide mobility from higher layers (RRC). Example aspects and embodiments may allow the protocol structure relative to the PDCP and RLC layers to be independent of intra-DU cell changes during intra-DU handover (serving cell and target cell provided by the same DU) (so the cell concept may be considered transparent to the PDCP layer). Example aspects and embodiments may allow the ability to not require data radio bearers (DRBs) and / or signaling radio bearers (SRBs) to be rebuilt when a cell changes within a DU, and not require security updates when a cell changes within a DU. Example aspects and embodiments may enable security key updates or re-establishment of upper layers such as the PDCP and RLC layers to be triggered independently of the handover process. For example, after the CU receives an update of the cell ID, the CU may initiate a security key update, or a re-establishment when it deems it necessary.

[0005] According to a first example aspect, there is disclosed an apparatus comprising:

[0006] means for sending at least one measurement report (e.g., a layer 1 measurement report about a target cell) to a network entity (e.g., a distributed unit of the network entity), the network entity providing a serving cell and a target cell for the apparatus, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer (e.g., the serving cell and the target cell share at least a portion of the radio resource control layer and / or have a common RRC entity);

[0007] means for receiving (e.g., at layer 2) from a network entity an indication of a handover configuration for handover of the apparatus to a target cell;

[0008] Means for performing handover in accordance with the handover configuration based on (eg, in response to) receiving (or triggered by) an indication of the handover configuration.

[0009] The apparatus may for example be or be comprised in a mobile entity such as a mobile telecommunication device or mobile phone or user equipment (UE) or terminal equipment.

[0010] According to a second exemplary aspect, a distributed unit of a network entity is disclosed, comprising:

[0011] - means for providing a serving cell and a target cell for an apparatus, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0012] - means for receiving at least one measurement report (e.g., a layer 1 measurement report regarding a target cell) from the apparatus;

[0013] means for determining whether the apparatus is to perform a handover to a target cell based on (e.g., in response to) at least one measurement report;

[0014] - means for sending to the apparatus (eg at layer 2 or MAC layer) an indication of a handover configuration for handing over the apparatus to a target cell based on determining that the apparatus is to perform the handover.

[0015] According to a third exemplary aspect, a central unit of a network entity is disclosed, comprising:

[0016] - a means for receiving a cell indicator indicating a target cell from a distributed unit or device of a network entity (e.g. receiving an indicator of a target cell, such as a CellID), the target cell and the serving cell being provided to the device by a distributed unit of the network entity, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0017] - means for determining to perform a cell action based on the cell indicator.

[0018] A network entity, in particular a network entity according to the second and / or third exemplary aspects, may for example be a base station, a radio access network (RAN) node (such as a gNB) or a part thereof or be included therein. The network entity may for example include a central unit and at least one distributed unit. The network entity may for example provide a cell of a cellular network, for example a serving or candidate / target cell, for the device via the distributed unit. The central unit according to the third exemplary aspect may for example be or be included in a server, a server cloud, a server system or a part thereof.

[0019] The apparatus, network entity, distributed unit or central unit according to any aspect may include: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to perform at least the specified steps.

[0020] The means of the device, network entity, distributed unit or central unit may be implemented in hardware and / or software. They may include, for example, at least one processor for executing processor instructions for performing the desired functions, at least one memory for storing instructions, or both. Alternatively, they may include, for example, circuits designed or configured to implement the desired functions, for example implemented in a chipset or chip (such as an integrated circuit). Typically, the device may include, for example, one or more processing devices or processors.

[0021] The device, network entity, distributed unit or central unit according to any aspect may include at least one processor; and at least one memory storing instructions, which, when executed by at least one processor, causes the device, network entity, distributed unit or central unit to at least perform the specified steps or steps of the method according to any example aspect. For example, the device according to the first example aspect may be a device including at least one processor and at least one memory storing instructions, which, when executed by at least one processor, causes the device to at least perform:

[0022] sending at least one measurement report to a network entity that provides a serving cell and a target cell for the apparatus, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0023] - receiving an indication of a handover configuration for handover of the apparatus to a target cell from a network entity;

[0024] - based on receiving an indication of the handover configuration, performing the handover according to the handover configuration.

[0025] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0026] (a) hardware circuit implementations only (e.g., implementations in analog and / or digital circuits), and

[0027] (b) a combination of hardware circuitry and software such as (where applicable):

[0028] (i) a combination of analog and / or digital hardware circuitry and software / firmware, and

[0029] (ii) any portion of a hardware processor having software (including a digital signal processor), software, and memory that work together to enable a mobile

[0030] The device of the phone or server performs various functions; and

[0031] (c) A hardware circuit and / or processor, such as a microprocessor or portion of a microprocessor, that requires software (e.g., firmware) for operation, but the software may not be present when not needed for operation.

[0032] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or a processor (or multiple processors) or a portion of a hardware circuit or a processor and its (or its) accompanying software and / or firmware. For example and if applicable to the particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0033] According to a fourth example aspect, there is disclosed a method, the method comprising:

[0034] sending at least one measurement report to a network entity, the network entity providing a serving cell and a target cell for the apparatus, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0035] - receiving an indication of a handover configuration for handover of the apparatus to a target cell from a network entity;

[0036] - Based on receiving the indication of the handover configuration, performing the handover according to the handover configuration.

[0037] The method according to the fourth example aspect may include the steps that the apparatus of the first example aspect is configured to perform or has components for performing. The method may be, for example, run, executed and / or controlled by an apparatus (according to the first example aspect) of, for example, a mobile entity (e.g., a mobile telecommunications device or a mobile phone or a user equipment or a terminal device).

[0038] According to a fifth example aspect, there is disclosed a method, the method comprising:

[0039] - providing a serving cell and a target cell for the device, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0040] - receiving at least one measurement report from the device;

[0041] - based on the at least one measurement report, determining whether the device is to perform a handover to a target cell;

[0042] - Based on determining that the apparatus is to perform a handover, sending to the apparatus an indication of a handover configuration for a handover of the apparatus to a target cell.

[0043] The method according to the fifth example aspect may comprise the steps that the distributed unit of the second example aspect is configured to perform or has components for performing the steps. The method may be run, performed and / or controlled by a distributed unit of a network entity such as a gNB, a RAN node, a base station or a part thereof (according to the second example aspect).

[0044] According to a sixth example aspect, a method is disclosed, the method comprising:

[0045] - receiving a cell indicator indicating a target cell from a distributed unit or device of a network entity, the target cell and the serving cell being provided to the device by a distributed unit of the network entity, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0046] - Performing a cell action based on the cell indicator determination.

[0047] The method according to the sixth example aspect may include the steps that the central unit of the third example aspect is configured to perform or has components for performing. The method may be run, executed and / or controlled by a central unit of a network entity such as a server, a server system, a server cloud, or a part thereof (according to the third example aspect).

[0048] According to another example aspect, a system is disclosed, comprising at least one device according to the first aspect (e.g., a mobile entity or a user equipment), at least one distributed unit of a network entity according to the second aspect (e.g., providing a service cell for the device), and a central unit according to the third aspect. The system can run, execute and / or be configured to perform any, some or all of the methods in the fourth, fifth, or sixth example aspects.

[0049] According to another example aspect, a computer program product is disclosed which, when executed by a processor of an apparatus, causes the apparatus to perform a method according to any example aspect, such as at least one of the fourth, fifth or sixth example aspects.

[0050] According to another example aspect, a device is disclosed, which is configured to run, execute and / or control the method according to the first example aspect or includes corresponding components for executing and / or controlling the method according to the first example aspect. According to another example aspect, a device is disclosed, including: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, causes the device to at least execute the method according to the first example aspect.

[0051] According to another example aspect, a network entity or a distributed unit of a network entity is disclosed, which is configured to run, execute and / or control a method according to a second example aspect or includes corresponding components for executing and / or controlling a method according to a second example aspect. According to another example aspect, a network entity or a distributed unit of a network entity is disclosed, comprising: at least one processor; and at least one memory storing instructions, which, when executed by at least one processor, causes the network entity or the distributed unit of the network entity to at least execute the method according to the second example aspect.

[0052] According to another exemplary aspect, a network entity or a central unit of a network entity is disclosed, which is configured to run, execute and / or control the method according to the third exemplary aspect or includes corresponding components for executing and / or controlling the method according to the third exemplary aspect. According to another exemplary aspect, a network entity or a central unit of a network entity is disclosed, comprising at least one processor; and at least one memory storing instructions, which, when executed by at least one processor, causes the network entity or the central unit of the network entity to at least execute the method according to the third exemplary aspect.

[0053] The disclosed apparatus, network entity, distributed unit or central unit according to any aspect may include only the disclosed components, such as apparatus, processor, memory, or may also include one or more additional components.

[0054] According to another example aspect, a computer program is disclosed which, when executed by a processor, causes a device (e.g., a server) to perform and / or control actions of a method according to any example aspect, such as at least one of the fourth, fifth, or sixth example aspects.

[0055] According to another example aspect, a computer-readable storage medium (eg, tangible and / or non-transitory) is disclosed, the computer-readable storage medium including at least one of the disclosed computer program product or computer program.

[0056] Any disclosure herein involving any example aspect, such as an apparatus, method, computer program, and computer-readable medium, should be understood to be equally disclosed relative to any subject matter according to the corresponding example aspect. Thus, for example, the disclosure of a method step should also be considered as a disclosure of a component for performing and / or causing the corresponding method step to be performed. Similarly, the disclosure of a component for performing and / or causing the method step to be performed should also be considered as a disclosure of the method step itself. The same applies to any paragraph describing at least one processor and at least one memory including instructions, the at least one memory and instructions being configured to cause the apparatus, network device, or core network device to perform at least steps together with the at least one processor.

[0057] In the following, example features and example embodiments of all aspects will be described in further detail.

[0058] The network entities can be divided into distributed units (DU) and central units (CU). The CU can be understood as a logical entity that includes network node functions, such as gNB functions, such as transmission of user data, mobility control, radio access network sharing, positioning, session management, etc., except for those functions specifically assigned to the DU. The DU can be understood as a logical entity that includes a subset of gNB functions. Its operation can be controlled by the CU. The gNB can consist of a gNB-CU and multiple gNB-DUs, each of which can provide multiple cells.

[0059] A cell that shares a layer (e.g., a packet data convergence protocol (PDCP) layer or a radio link control (RLC) layer) or a configuration of a layer with another cell can be understood as the cell (e.g., a serving cell) and the other cell (e.g., a candidate cell or a target cell) having at least one common configuration for the layer (e.g., the configuration is independent of the cell).

[0060] For example, a cell that shares (at least one) protocol configuration of a radio resource control layer with another cell can be understood as the cell (e.g., a serving cell) and another cell (e.g., a candidate cell or a target cell) having at least one common RRC entity. Therefore, at least the serving cell and the target cell that share the protocol configuration of the radio resource control layer can be or include a serving cell and a target cell having at least one common RRC entity. For example, the radio resource control layer for the serving cell and the target cell can be based on the same protocol configuration. For example, the serving cell and the target cell have a shared protocol stack, for example, up to the radio resource control layer. This can allow the shared layer to be not cell-specific or transparent to the cell concept. For example, a cell can be defined or managed (e.g., only) at layer 2, such as a medium access control layer, so that, for example, only layer 2 and layer 1 may need to be reconfigured after switching to another cell. For example, a handover configuration or a handover parameter included in the handover configuration can be used to perform the reconfiguration. The handover can be referred to as a cell handover. The handover configuration can be an incremental configuration. In the incremental configuration, the difference or increment between the current configuration and the new configuration is signaled instead of the entire new configuration being signaled. For example, incremental configuration may be used to update the configuration of a UE with new parameters by signaling only the parameters that have changed.

[0061] For example, the serving cell and the target cell may share the entire layer, for example by using a common configuration of all functions of the layer, or the serving cell and the target cell may share only a subset of the functions of the layer. For example, the shared protocol configuration may include only (radio resource control) parameters not related to mobility, which may be used to configure the functions of the layer other than the functions related to mobility. For example, although the radio resource control layer (e.g., with complete RRC functions) may be shared between the serving cell and the target cell, the distributed unit may be an entity configured with a mobility radio resource control layer, i.e., an additional radio resource control layer specifically configured to be able to perform (substantially) all necessary device mobility operations, e.g., without the involvement of the radio resource control layer of the central unit. This concept of splitting the RRC layer into a shared RRC layer (which may be labeled RRC-H) and a mobility radio resource control layer (which may be labeled RRC-L) may be referred to as dual RRC. The RRC-H may or may not be aware of the concept of cells, e.g., the concept of the serving cell and the target cell. In the case where the RRC-H knows the cell, the intra-DU switching can be determined by the DU, where the DU sends a cell indicator indicating the target cell to the RRC-H used by the CU via RRC-L, for example indicating that the target cell is associated with the device. In the case where the RRC-H is unaware of the cell, the DU can manage all functions related to the mobility of the device, so that, for example, an interface between the RRC-H and the RRC-L may not be required. Therefore, the mobility radio resource control layer RRC-L can be dedicated to the cell, while the radio resource control layer RRC-H can be shared between different cells (for example, one cell shares (at least one) protocol configuration of the radio resource control layer with another cell). RRC-L can be understood as a distributed part of the radio resource control layer, or as an additional (separate) radio resource control layer for handling mobility.

[0062] Reconstructing a layer may be understood as reconfiguring the layer, for example, based on configuration parameters of the layer included in the reconstruction indication.

[0063] The network entity may, for example, identify a set of candidate (target) cells for the device based on the received measurement reports, wherein the candidate (target) cells may be provided by the first network entity or the second network entity, and configure the network entity to provide the candidate (target) cells for use by the device (e.g., UE).

[0064] For example, the device may perform a handover to a target cell (e.g., in a set of candidate target cells), for example, based on receiving an indication of a handover configuration. The indication of the handover configuration may be referred to as a handover trigger. In the handover, the serving cell of the device changes from the (original) serving cell to the target cell. The handover may be, for example, a conditional handover (CHO) to a target cell (e.g., a set of target candidate cells), or a conditional primary serving cell (PCell) change (CPAC) to a target PCell of a set of candidate target cells. In CHO or CPAC, a set of potential target cells may be prepared in advance for the device by the current serving network entity (i.e., a network entity that provides a cell through which the device is connected to the network). The device may receive and save a set of handover commands for each candidate target cell or cell group. The device may determine whether a predefined condition (such as a measured signal quality exceeding a predefined quality threshold) is met, and perform a handover (CHO or CPAC) when it is determined that the condition is met.

[0065] A configuration group may indicate a group of cells, for example, including a serving cell and a target cell that share at least a protocol configuration of a radio resource control layer, wherein the cells share at least a protocol configuration of the radio resource control layer, for example, at least a portion of the radio resource control layer of the cells in the cell group is based on the same protocol configuration. A configuration index may indicate a configuration of a specific cell (e.g., a target cell) within the cell group. A configuration index may be associated with a cell group, i.e., it may be combined with an indication of a configuration group to identify a specific cell.

[0066] The indication of the handover may be or may be included in a media access control control element (MACCE) or a radio resource control (RRC) message. The indication may be, for example, a handover trigger for triggering the handover according to the handover configuration. For example, the indication may be or may be included in a MAC-CE cell change trigger with or without a CHO condition, an RRC message or command "RRCReconfigurationWithSync", or an RRC message or command "RRCReconfigurationWithuoRACH" with or without a CHO condition. Execution of the handover may be based on receiving an indication of the handover configuration. For example, the handover is performed in response to receiving an indicator of the handover or the handover is triggered by receiving an indicator of the handover.

[0067] The serving cell and target cell managed at Layer 2 (e.g., MAC layer) may be understood as cell concepts defined at Layer 2 (e.g., rather than Layer 3), so that (basically) all cell-related operations (e.g., switching to another cell) are managed or performed at Layer 2, and, for example, Layer 3 is not involved in such cell-related operations.

[0068] For example, the completion of the handover and / or the new cell identity may be indicated from the RRC-L to the RRC-H according to a condition (e.g., a reporting condition). The reporting condition may be, for example, that the target cell is part of a cell group, which may have been preconfigured. The cell group may be or include a cell at the border of the cell coverage area of ​​the distributed unit currently providing the serving cell for the device.

[0069] When the UE is located in a cell group at the border of the cell coverage area of ​​the DU, the central unit (CU) may be aware, for example by receiving a corresponding indication from the DU, that it needs to configure the UE with mobility measurements, such as layer 3 measurements, to be handled by the CU. Alternatively, the cell group may, for example, be or include mobility tracking areas (which may, for example, be cells covering a route along a highway and / or cells covering a pedestrian area) and / or cells with the same or different frequency layers. For example, such a cell group may enhance the configuration of the device as needed (e.g., by a higher layer).

[0070] The reporting condition may include or may be a cell change count threshold (e.g., the number of handovers within a specific time interval or the frequency at which a device switches to a target cell), which may allow, for example, a higher layer (e.g., a central unit) to update security based on handover frequency rather than time. Updating security may include, for example, sending a key indication of a security key so that the device can generate a new security key based on the key indication. The reporting condition may include or may be a traversal condition, for example, a condition that is satisfied when the device has traversed certain cells or cell groups (e.g., performed a handover to certain cells or cells in a cell group). By reporting the condition, a security update may be triggered in the MAC layer (in the PDCP layer).

[0071] The reporting conditions (e.g., cell groups, or cell handover counts) may be configured to a layer in the network that handles cell handovers, which may be a distributed unit and / or a medium access control layer or a mobility radio resource control layer (e.g., RRC-L). Additionally or alternatively, the reporting conditions may be configured or pre-configured to a device (e.g., UE).

[0072] The cell indicator indicating the target cell may be an identifier of the target cell, such as CellID.

[0073] Determining whether the device is located at the border of the area of ​​cell coverage provided by the distributed unit can be performed by a network entity (e.g., a DU of the network entity), and the network entity identifies the serving and / or target cell as a cell on the edge of the area of ​​cell coverage provided by the network entity. The cell at the border can, for example, be included in a dedicated cell group known to the network entity.

[0074] The security key may be a (master) key used to establish a security context with a network entity via a target cell or a cell group provided by a network entity including the target cell. For example, the security key may be used to establish a security context with a network entity via any cell in the cell group.

[0075] The security key (e.g., KgNB) may be generated by a network entity or a device, wherein the same security key may be derived by the device and the network entity when generated relative to the same method using the same parameters. For example, the security key may be generated based on at least one of the following: a physical cell identifier of the cell (e.g., CellID), a frequency of the cell, a next hop chain count value not used by the network entity, a security key for establishing a security context with the network entity via a (previous) serving cell. The security key may be generated based on a non-access stratum (NAS) level key.

[0076] The key indication may include information about which parameters and / or methods to use or the parameters and methods may be predefined by the network, so that, for example, a device receiving the key indication may generate a security key based on the key indication.

[0077] According to an example of the first, second, fourth or fifth example aspect, the indication of the switch indicates at least one of a configuration group or a configuration index.

[0078] According to an example of the first, second, fourth or fifth example aspect, the handover configuration includes handover parameters for layers that are not shared between the serving cell and the target cell, and wherein performing the handover according to the handover configuration includes reconfiguring the layers (or portions of the layers) that are not shared between the serving cell and the target cell based on the handover parameters. (And, for example, without reconfiguring the layers that are shared between the serving cell and the target cell).

[0079] According to an example of the first, second, fourth or fifth example aspects, the switching configuration includes switching parameters only for layer 2 (e.g., MAC layer) and switching parameters for layer 1 (e.g., PHY layer) (but, for example, does not include switching parameters for layer 3), and wherein performing switching according to the switching configuration includes reconfiguring layer 1 and layer 2 based on the switching configuration.

[0080] According to an example of the first, second, fourth or fifth example aspect, the serving cell and the target cell are managed at layer 2. For example, the distributed unit may provide a serving cell and a set of candidate (target) cells configured by a protocol sharing a common RRC entity or radio resource control layer, wherein the target cell is a cell in the set of candidate (target) cells to perform handover. Then, for example, all actions related to handover are performed or managed (substantially) at layer 2.

[0081] According to an example of the first, second, fourth or fifth exemplary aspect, the serving cell and the target cell also share at least one of a packet data convergence protocol (PDCP) layer or a radio link control (RLC) layer (e.g., a PDCP layer) (e.g., the packet data convergence protocol or the radio link control layer can be based on the same configuration in the serving cell and the target cell, i.e., the corresponding layer does not need to be reestablished or reconfigured after switching). For example, the packet data convergence protocol layer or the radio link control layer can be configured according to the same configuration / configuration parameters for the serving cell and the target cell (or a set of candidate cells) in the device and the network entity. The sharing of the corresponding layer may involve only a certain set of functions of the layer, so that only a part of the layer is shared (i.e., the remaining part will be the unshared PDCP or RLC layer).

[0082] According to an example of the first example aspect, the apparatus further includes:

[0083] - Means for sending a completion indicator (eg, ACK) indicating handover completion to a network entity upon completion of the handover (eg, after applying the handover configuration).

[0084] According to an example of the first example aspect, the apparatus further includes:

[0085] means for receiving a key indication indicating a security key from a network entity after performing a handover;

[0086] Means for generating a security key based on a key indication.

[0087] According to an example of the first example aspect, the apparatus further includes:

[0088] means for receiving, after performing a handover, from a network entity a reestablishment indication including an indication of configuration parameters for a layer (e.g., a PDCP layer);

[0089] Means for reconstructing the layer based on the reconstruction indication.

[0090] According to an example of the first example aspect, the apparatus further includes:

[0091] means for receiving a handover configuration from the network entity after performing the handover, the handover configuration being for a layer 3 handover to a cell provided by another network entity or to a layer 3 handover to a cell provided by a distributed unit not providing the serving cell;

[0092] Means for performing a layer 3 handover based on receiving a handover configuration for the layer 3 handover.

[0093] According to an example of the first example aspect, the apparatus further includes:

[0094] - means for determining whether the handover is complete;

[0095] Means for sending a cell indicator indicating a target cell (eg, sending an identifier of the target cell, such as CellID) to a central unit of a network entity based on determining that the handover is completed.

[0096] According to an example of the first example aspect, the apparatus further includes:

[0097] - Means for receiving a reporting condition from a network entity, wherein sending the cell indicator is performed based on determining that a reporting condition is met (the reporting condition is, for example, that the target cell is or is not part of a preconfigured set of cells).

[0098] According to an example of the second or fifth example aspect, determining whether the device is to perform a handover is performed in layer 2, specifically a medium access control layer.

[0099] According to an example of the second or fifth example aspect, determining whether the apparatus is to perform the handover is performed in a mobility radio resource control layer (e.g., RRC-L), wherein the mobility radio resource control layer is a radio resource control layer used by a distributed unit;

[0100] According to an example of the second example aspect, the distributed unit further comprises:

[0101] -Components for determining whether the handover is complete;

[0102] Means for sending a cell indicator indicating the target cell (eg, sending an identifier of the target cell) to a central unit of a network entity based on determining that the handover is completed.

[0103] According to an example of the second or fifth example aspect, the sending of the cell indicator is performed based on determining that a reporting condition is met (the reporting condition is, for example, that the target cell is not part of a preconfigured set of cells).

[0104] According to an example of the second example aspect, the distributed unit further comprises:

[0105] Means for receiving, from the apparatus, a completion indicator indicating completion of the handover based on sending the indication of the handover, wherein sending the cell indicator is based on receiving the completion indicator.

[0106] According to an example of the second example aspect, the distributed unit further comprises:

[0107] - means for determining whether a device is located at a border of an area covered by a cell provided by said distributed unit;

[0108] Means for sending a boundary indication (eg, "DU Boundary: TRUE") to a central unit of a network entity based on determining that the device is located at said boundary, the boundary indication indicating that the device is located at a boundary of an area of ​​unit coverage provided by a distributed unit.

[0109] According to an example of the third example aspect, the cell action comprises a security key update, the central unit further comprising:

[0110] - means for sending a key indication indicating a security key (e.g., a key) to the device based on determining to perform the security key update. Means for generating a security key by the device).

[0111] According to an example of the third example aspect, the cell action comprises a layer reconstruction of a layer, the central unit further comprising:

[0112] means for performing layer reconstruction based on the determination, the apparatus sending a reconstruction indication including an indication of configuration parameters for the layer;

[0113] - Means for rebuilding the layer based on configuration parameters of the layer (eg, by applying the configuration parameters).

[0114] According to an example of the third example aspect, the cell action comprises determining a handover configuration for a layer 3 handover to a cell provided by another network entity or a cell provided by another distributed unit of the network entity, the central unit further comprising:

[0115] means for determining a handover configuration for a layer 3 handover based on determining to perform a cell action based on the cell indicator;

[0116] - Means for transmitting a handover configuration for layer 3 handover to the device.

[0117] According to an example of the third example aspect, a handover configuration for layer 3 handover is determined based on the apparatus being located at a boundary of an area covered by a cell provided by a distributed unit.

[0118] According to an example of the third example aspect, the central unit further comprises:

[0119] - means for receiving a boundary indication from a distributed unit indicating that a device is located at a boundary of an area covered by a cell provided by said distributed unit; wherein a handover configuration for a layer 3 handover is determined based on the boundary indication.

[0120] According to an example of the third example aspect, the cell action includes determining a reporting condition (e.g., the device sends a cell indicator based on determining that the reporting condition is met), and the central unit further includes:

[0121] - means for determining a reporting condition based on determining to perform a cell action based on a cell indicator;

[0122] - Means for sending a report condition to a device or a distributed unit.

[0123] According to an example of the third example aspect, the central unit further comprises:

[0124] Means for maintaining a configuration of at least one of a packet data convergence protocol layer or a radio link control layer.

[0125] According to an example of the third or sixth exemplary aspect, the serving cell and the target cell are managed at layer 2.

[0126] According to an example of the fourth example aspect, the method further comprises:

[0127] Based on completing the handover, a completion indicator is sent to the network entity indicating that the handover is complete.

[0128] According to an example of the fourth example aspect, the method further comprises:

[0129] After performing the handover, receiving a key indication from the network entity indicating a security key;

[0130] According to an example of the fourth example aspect, the method further comprises:

[0131] After performing the handover, receiving a reestablishment indication from the network entity including an indication of a configuration parameter of the layer;

[0132] The layer is reconstructed based on the reconstruction indication.

[0133] According to an example of the fourth example aspect, the method further comprises:

[0134] After performing the handover, receiving from the network entity a handover configuration for performing a layer 3 handover to a cell provided by another network entity or performing a layer 3 handover to a cell provided by a distributed unit that does not serve the cell;

[0135] Based on receiving the handover configuration of the layer 3 handover, a layer 3 handover is performed.

[0136] According to an example of the fourth example aspect, the method further comprises:

[0137] - Determine whether the switch is completed;

[0138] Based on determining that the handover is completed, a cell indicator indicating a target cell is sent to a central unit of the network entity.

[0139] According to an example of the fourth example aspect, the method further comprises:

[0140] - Receiving a reporting condition from a network entity, wherein sending the cell indicator is performed based on determining that the reporting condition is met.

[0141] According to an example of the fifth example aspect, the method further comprises:

[0142] - Determine whether the switch is completed;

[0143] Based on determining that the handover is completed, a cell indicator indicating a target cell is sent to a central unit of the network entity.

[0144] According to an example of the fifth example aspect, the method further comprises:

[0145] Based on transmitting the indication of the handover, a completion indicator is received from the device indicating completion of the handover, wherein transmitting the cell indicator is based on receiving the completion indicator.

[0146] According to an example of the fifth example aspect, the method further comprises:

[0147] - determining whether the device is located at the border of the area of ​​cell coverage provided by the distributed unit;

[0148] Based on determining that the device is located at the border, a border indication is sent to the central unit of the network entity, the border indication indicating that the device is located at the border of the area of ​​cell coverage provided by the distributed unit.

[0149] According to an example of the sixth example aspect, the cell action comprises a security key update, and the method further comprises:

[0150] Based on determining to perform a security key update, a key indication indicating a security key is sent to the device.

[0151] According to an example of the sixth example aspect, the cell action includes layer reconstruction of a layer, and the method further includes:

[0152] Based on determining to perform a reconstruction of the layer, sending a reconstruction indication to the device, the reconstruction indication including an indication of a configuration parameter of the layer;

[0153] Rebuilds a layer based on its configuration parameters.

[0154] According to an example of the sixth example aspect, the cell action comprises determining a handover configuration for a layer 3 handover to a cell provided by another network entity or a cell provided by another distributed unit of the network entity, the method further comprising:

[0155] determining a handover configuration for a layer 3 handover based on determining to perform a cell action based on the cell indicator;

[0156] - Send handover configuration for layer 3 handover to the device.

[0157] According to an example of the sixth example aspect, the method further includes:

[0158] - receiving a boundary indication from a distributed unit, the boundary indication indicating that the device is located at a boundary of an area of ​​cell coverage provided by the distributed unit; wherein a handover configuration for a layer 3 handover is determined based on the boundary indication.

[0159] According to an example of the sixth example aspect, the cell action includes determining a reporting condition, and the method further includes:

[0160] - based on determining to perform a cell action based on the cell indicator, determining a reporting condition;

[0161] Send a report condition to a device or distributed unit.

[0162] According to an example of the sixth example aspect, the method further includes:

[0163] A configuration of at least one of a packet data convergence protocol layer or a radio link control layer is maintained.

[0164] The features and exemplary embodiments described above may equally relate to different aspects, for example, components for performing method steps may equally disclose the method steps, and vice versa, for example, the method steps described in connection with the fourth example aspect may equally disclose the corresponding components for performing the method steps by a device according to the first example aspect, and vice versa; the method steps described in connection with the fifth example aspect may equally disclose the corresponding components for performing the method steps by a network entity according to the second example aspect, and vice versa; the method steps described in connection with the sixth example aspect may equally disclose the corresponding components for performing the method steps by a core network entity according to the third example aspect, and vice versa.

[0165] It should be understood that the presentation in this section is by way of example only and is not restrictive.

[0166] Other features will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It should be understood, however, that the drawings are designed for illustrative purposes only and not as a definition of limitation, reference being made to the appended claims. It should be further understood that the drawings are not drawn to scale and that they are merely intended to conceptually illustrate the structures and procedures described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0167] The accompanying drawings show:

[0168] Figure 1 is a schematic diagram illustrating an example system;

[0169] Figure 2 A flowchart showing an example implementation of a method according to a fourth example aspect;

[0170] Figure 3 A flowchart showing an example of a method according to a fifth example aspect;

[0171] Figure 4 A flowchart showing an example of a method according to a sixth example aspect;

[0172] Figure 5 is an example of a protocol stack architecture;

[0173] Figure 6 is an example of a protocol stack architecture;

[0174] Figure 7 An example message sequence chart showing examples of methods according to the fourth, fifth and sixth example aspects;

[0175] Figure 8 An example message sequence chart showing examples of methods according to the fourth, fifth and sixth example aspects;

[0176] Fig. 9 An example message sequence chart showing examples of methods according to the fourth, fifth and sixth example aspects;

[0177] Fig.10 An example message sequence chart showing examples of methods according to the fourth, fifth and sixth example aspects;

[0178] Fig.11 An example message sequence chart showing examples of methods according to the fourth, fifth and sixth example aspects;

[0179] Fig.12 An example message sequence chart showing examples of methods according to the fourth, fifth and sixth example aspects;

[0180] Fig.13 is a schematic block diagram of an example of an apparatus according to the first aspect and / or an example embodiment of a network unit according to the second and / or third example aspects;

[0181] Fig.14 is a schematic diagram of an example of a (tangible and / or non-transitory) computer-readable storage medium. DETAILED DESCRIPTION

[0182] The following description is used to deepen understanding and should be understood to supplement the description provided in the above overview section of this specification and read together with it. Some aspects may have different terms than, for example, the terms provided in the above description. For example, switching may be described as a cell change or a cell handover. However, the skilled person will understand that those terms refer to the same subject matter, for example, more specific.

[0183] Figure 1A schematic diagram of an example system is shown, for example, a system according to the example aspects disclosed above. A network entity (or a distributed unit of a network entity) 101 provides a (current) serving cell 103 and a (candidate) target cell 104 to an apparatus 102. When the apparatus moves 105 and sends measurement reports on, for example, the serving cell 103 and the target cell 104, the network entity or the distributed unit 101 may send an indication of a handover configuration for a handover of the apparatus 102 to the target cell 104 (e.g., included in a handover trigger, such as a MACCE trigger). Subsequently, the apparatus may perform a handover to the target cell 104. The apparatus 102 may be a user equipment UE.

[0184] The described example embodiments may be implemented in a radio system. Some examples of suitable communication networks include 5G networks and / or 6G networks. The 3GPP solution for 5G is called New Radio (NR). 6G is envisioned as a further development of 5G. NR has been envisioned to use multiple-input multiple-output (MIMO) multi-antenna transmission technology, deploy more base stations or nodes (the so-called small cell concept) than the current network of LTE, including macro sites, which operate in conjunction with smaller local access nodes and may also adopt multiple radio technologies for better coverage and enhanced data rates. 5G will likely consist of more than one radio access technology / radio access network (RAT / RAN), each optimized for certain use cases and / or spectrum. 5G mobile communications may have a wider range of use cases and related applications, including video streaming, augmented reality, different data sharing methods, and various forms of machine-type applications, including vehicle safety, different sensors, and real-time control. 5G is expected to have multiple wireless interfaces, namely below 6GHz, cmWave, and mmWave, and can be integrated with existing traditional wireless access technologies, such as LTE.

[0185] The current architecture in LTE networks is distributed in the radio and concentrated in the core network. Low-latency applications and services in 5G may need to bring content close to the radio, which leads to local interruptions and multi-access edge computing (MEC). 5G may enable analysis and knowledge generation to occur at the data source. This method may need to utilize resources that may not be continuously connected to the network, such as laptops, smart phones, tablet computers and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content near cellular subscribers to obtain faster response times. Edge computing covers a wide variety of technologies, such as wireless sensor networks, mobile data collection, mobile signature analysis, collaborative distributed peer-to-peer self-organizing networking and processing, which can also be classified as local cloud / fog computing and grid / grid computing, dew computing, mobile edge computing, cloud gathering, distributed data storage and retrieval, autonomous self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (large-scale connectivity and / or latency-critical), critical communications (autonomous vehicles, traffic safety, real-time analysis, time-critical control, medical applications). Network function virtualization (NVF) and software-defined networking (SDN) can be used to bring edge clouds into RAN. Using edge cloud can mean that access node operations are performed at least partially in a server, host or node operatively coupled to a remote radio head or base station including a radio portion. Network slicing allows multiple virtual networks to be created on top of a common shared physical infrastructure. The virtual networks are then customized to meet the specific needs of an application, service, device, customer or operator.

[0186] In wireless communications, node operations may be performed at least partially in a central / centralized unit CU (e.g., a server, host, or node) operatively coupled to a distributed unit DU (e.g., a radio head / node). Node operations may also be distributed between multiple servers, nodes, or hosts. It should also be understood that the distribution of work between core network operations and base station operations may vary depending on the implementation. Therefore, the 5G network architecture may be based on the so-called CU-DU split. One gNB-CU controls several gNB-DUs. The term 'gNB' in 5G may correspond to an eNB in ​​LTE. A gNB (one or more) may communicate with one or more UEs. A gNB-CU (central node) may control multiple spatially separated gNB-DUs, at least used as transmit / receive (Tx / Rx) nodes. However, in some embodiments, the gNB-DU (also referred to as DU) may include, for example, a radio link control (RLC), a medium access control (MAC) layer, and a physical (PHY) layer, and the gNB-CU (also referred to as CU) may include layers above the RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC), and an Internet Protocol (IP) layer.

[0187] A plurality of network entities 101 (e.g., gNBs (access points / nodes)), each of which includes a CU and one or more DUs, may be connected to each other via an Xn interface that the gNBs may negotiate. The gNBs may also be connected to a 5G core network (5GC) via a next generation (NG) interface, which may be the 5G equivalent of an LTE core network. Such a 5G CU-DU split architecture may be implemented using a cloud / server, such that the CU with higher layers is located in the cloud, and the DU is closer to or includes the actual radio and antenna units.

[0188] Figure 2 2 is a flowchart illustrating an example of a method 200 according to a fourth example aspect. The example method may be performed or implemented by an apparatus (eg, a user device or a user apparatus) and includes:

[0189] sending 201 at least one measurement report to a network entity, the network entity providing a serving cell and a target cell for the device, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0190] - receiving 202 from a network entity an indication of a handover configuration for handover of the device to a target cell;

[0191] Based on receiving the indication of the handover configuration, the handover is performed 203 according to the handover configuration.

[0192] Figure 3 is a flow chart illustrating an example of a method 300 according to a fifth example aspect. The example method may be performed or implemented by a distributed unit of a network entity (e.g., a RAN node or a gNB), and comprises:

[0193] - providing 301 a serving cell and a target cell for the apparatus, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0194] - receiving 302 at least one measurement report from a device;

[0195] Based on the at least one measurement report, determining 303 whether the device is to perform a handover to a target cell;

[0196] Based on determining that the apparatus is to perform a handover, sending 304 to the apparatus an indication of a handover configuration for a handover of the apparatus to a target cell; and

[0197] - Sending 305 a cell indicator indicating the target cell to a central unit of the network entity.

[0198] Figure 44 is a flow chart showing an example implementation of a method 400 according to the sixth example aspect. The example method may be performed or implemented by a central unit of a network entity, the central unit being located on a server, for example, and comprising:

[0199] - receiving 401 a cell indicator indicating a target cell from a distributed unit or device of a network entity, the target cell and the serving cell being provided to the device by a distributed unit of the network entity, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer;

[0200] - Determine 402 to perform a cell action based on the cell indicator.

[0201] For example, to enhance signaling, for example, the UE does not have to decode the configuration of all layers to perform a handover, a protocol stack architecture (e.g., according to any aspect; the serving cell and the target cell share at least one protocol configuration of the radio resource control layer) is disclosed, which defines the cell at the MAC, which can achieve a cell-free architecture for the PDCP and RLC layers. This can facilitate deployment in a cloud-native environment, where the CU is located in the cloud and the DU is located at the edge of the cloud. The concept of the cell can be used for network optimization purposes. For example, when performing RACH during handover, and how to reuse resources across cells. According to the disclosed architecture (e.g., according to any aspect), the concept of the cell can be separated in a higher layer, which can simplify the handover process by moving the concept of the cell to the MAC (sub) layer that defines and manages the cell. CU-DU interaction can be minimized. For example, the DU can be reconfigured only when necessary. For example, this can allow hiding mobility from higher layers (e.g., Layer 3, RRC, PDCP, RLC). Different examples and example aspects may involve a single RRC or a dual RRC. Examples and example aspects may allow handover to be performed without RRC reconfiguration. Defining cells at the MAC may focus on intra-DU handover.

[0202] The following provides an example of hiding mobility from higher layers:

[0203] PDCP, RLC reestablishment may not be required during handover. DRB and SRB reestablishment is not required during handover, which may enable LTM. Using the disclosed protocol architecture, since cells may be defined and managed at the MAC layer, RRC reconfiguration commands may not be required to activate LTM. Cell handover or handover may be performed from lower layer measurements. In addition, the reestablishment of the PDCP, RLC, RRC layers may be separated from the handover. For example, security key updates may be separated. For example, the separation may be extended to the reestablishment separation of the PDCP, RLC, RRC layers.

[0204] When a new cell ID is received from the MAC in the CU, the CU may decide to perform a security key update, or trigger a PDCP reestablishment. The disclosed architecture may allow the reestablishment of the PDCP, RLC, and RRC layers to be separated from the handover process. Not just triggered by handover. The network may implement an algorithm to determine the security of the environment, and, for example, trigger a security update when it deems it necessary.

[0205] For example (according to any aspect):

[0206] 1. After the handover is completed, the MAC may inform the CU of the new cell ID, for example, by sending a cell indicator indicating the target cell to the CU.

[0207] 2. Upon receiving the new cell ID in the CU from the MAC, the CU may make a decision, for example, by receiving a cell indicator indicating the target cell from a distributed unit of a network entity or device. The CU may determine to perform a cell action

[0208] a. Trigger PDCP reestablishment (e.g., determine the reestablishment (PDCP) layer)

[0209] b. Update security keys (eg, determine to perform security key update).

[0210] c. If the UE is at a DU boundary, configure L3 handover (e.g., determine the handover configuration for layer 3 handover based on the device being at the boundary of an area covered by a cell provided by a distributed unit)

[0211] Examples of any aspect may involve single RRC, dual RRC, UE driven. In a single RRC, the reconstruction of PDCP, RLC and even RRC layers may be separated. Security key updates, for example, may not be triggered by switching. In dual RRC, there may also be a PDCP layer in RRC-L, so the separation can be understood as separating the reconstruction of PDCP-H in the CU from the PDCP-L in the DU. In other words, security updates can be performed at different times between the CU and the DU.

[0212] Examples of any aspect may involve intra-DU handover.

[0213] The cells in the MAC protocol stack architecture as disclosed above can hide mobility from higher layers (i.e., RLC, PDCP, and RRC layers). For example, (according to examples of any aspect) security keys may not need to be changed because the PDCP entity has not changed. However, for security reasons, the security keys can at least be updated periodically. For example: if the keys are static for a long time, a malicious attacker may have more time to crack / decipher / decode them. As disclosed, cells are defined and managed at the MAC layer, which then allows the MAC to manage mobility. Separating the re-establishment of the PDCP, RLC, or even RRC layers (for example, according to examples of any aspect) can enable the MAC to link periodic security updates to the frequency of cell changes or the traversal of cell groups by notifying higher layers of the traversed cells. The interface between the MAC and CU disclosed herein can allow the MAC layer to trigger security updates in the PDCP sublayer.

[0214] 1. Single RRC (e.g., in 5G framework)

[0215] The MAC layer at the DU may inform the RRC layer at the CU of the new cell ID. This new cell ID information may be required at the CU, as the CU may need to at least know where the UE is for sending paging control information, and the possibility of updating security keys. In addition, the core network may also require cell ID information from the CU.

[0216] 2. Dual RRC (e.g. one (full-function) RRC denoted as RRC-H, a separate RRC at the DU may be responsible for mobility at the MAC, denoted as RRC-L)

[0217] RRC-H may know the entity of the cell. Intra-DU mobility may occur at the DU. RRC-L may send an indication to RRC-H that a new cell ID is associated with a specific UE. This example may also allow extension to an AI / ML framework. Optimization based on updates from mobility may allow prediction of future mobility.

[0218] The RRC-H may not know the entity of the cell. As a result, the RRC-L may fully handle the mobility. An interface for mobility may not be required between the RRC-H and the RRC-L.

[0219] exist Figure 5 and 6 The architecture and instructions between DU and CU are described in.

[0220] Figure 5Examples of protocol stack architectures 501, 502 that can be used in examples according to any aspect are shown. In the example protocol stack architecture 501, for example, a serving cell (cell 1) and a target cell (cell 2) provided for a device (UE1) share a protocol configuration of a radio resource control layer, for example. They share a radio resource control layer (RRC). In this example, the serving cell and the target cell further share a packet data convergence protocol layer and a radio link control layer (e.g., a packet data convergence protocol layer and a radio link control layer). The packet data convergence protocol (PDCP) layer and the radio link control (RLC) layer are based on a common configuration for the serving cell and the target cell. The RRC, PDCP, and RLC layers are transparent to the concept of cells. The serving cell and the target cell are managed 507 in the MAC layer (e.g., scheduling, priority processing). The RRC and PDCP layers are used by the CU 505, and the RLC and MAC layers are used by the DU 506. After the device UE1 performs handover 508, the DU 506 sends 503 a cell indicator indicating the target cell to the CU 505 via the MAC layer 507 (or UE1). Similarly, after the UE2 performs handover 509 from the serving cell (cell 3) to the target cell (cell 4), the DU 506 sends 504 a cell indicator indicating the target cell (cell 4) to the CU 505 via the MAC layer 507 (or UE2).

[0221] Figure 5 An architecture for a single RRC may be involved. For each UE (UE1, UE2), an RRC connection may be created and anchored in the current serving cell, which sets all parameters for PDCP, RLC, MAC, and PHY in idle mode, inactive mode, and connected mode. In idle and inactive modes, RRC messages may bypass the PDCP sublayer and the RLC sublayer and reach the MAC sublayer. In connected mode, RRC messages may be integrated and encrypted in the PDCP sublayer and segmented in the RLC layer. When the UE moves across cells within the DU under the disclosed architecture, the change of the serving cell may be activated by the MAC-CE based on the reception of the measurement report DU. Unlike an RRC reconfiguration command that may trigger an L3 HO or trigger preparation for an LTM, the trigger may be a MAC-CE that may contain updated parameters related to the MAC and PHY layers (e.g., which may enhance the mobility of 6G). Once the handover is complete (which may be marked by the UE sending back a response), the DU may send an indication of the new cell ID to which the UE is switched to the RRC layer. The RRC may then decide whether it will trigger an upper layer PDCP re-establishment so that new security keys may be generated. The interface between the MAC and the RRC may contain at least the new cell ID. Other fields may be open for configuration.

[0222] Figure 6 An example of a protocol stack architecture 601, 602 that can be used in an example according to any aspect is shown. In the example protocol stack architecture 601, for example, a serving cell (cell 1) and a target cell (cell 2) provided for a device (UE1) share a protocol configuration of a radio resource control layer, for example. They share (split) a radio resource control layer (RRC-H), which can correspond to a dual RRC. In this example, the distributed unit also uses a mobility radio resource control layer 607-1 (labeled as RRC-L) to determine whether the device UE1 is to perform a handover 608. The mobility radio resource control layer 607-1 is also used to send 603 a cell indicator indicating the target cell (cell 2) to the CU 605. Further, the serving cell and the target cell share a packet data convergence protocol layer and a radio link control layer (e.g., a packet data convergence protocol layer and a radio link control layer). The packet data convergence protocol (PDCP) layer and the radio link control (RLC) layer are based on a common configuration for the serving cell and the target cell. The RRC, PDCP and RLC layers are transparent to the concept of cells. The serving cell and the target cell are managed (e.g., scheduling, priority handling) 607 in the MAC layer. The RRC and PDCP layers are used by the CU 605, and the RLC, mobility radio control layer, and MAC layer are used by the DU 606. Likewise, after the UE2 performs a handover 609 from the serving cell (cell 3) to the target cell (cell 4), the DU 506 sends 604 a cell indicator indicating the target cell (cell 4) to the CU 605 via the mobility radio control layer 607-2.

[0223] Figure 6An architecture for dual RRC may be involved. For each UE, an RRC connection may be created and anchored in the current serving cell, which sets all parameters for PDCP, RLC, MAC, and PHY in idle mode, inactive mode, and connected mode. In the case of dual RRC, there may be two RRC units (e.g., RRC entities), but they may belong to the same serving cell. One may be an RRC-H located in the CU, and one may be an RRC-L located in the DU. In idle and inactive modes, RRC messages from the RRC-H may bypass the PDCP sublayer and the RLC sublayer and reach the MAC sublayer. In connected mode, RRC messages may be integrated and encrypted in the PDCP sublayer and segmented in the RLC layer. When the UE is moving across cells within a DU under the disclosed architecture, the change of the serving cell may be activated by an RRC reconfiguration command based on the measurement report received by the DU, because there may be an RRC unit in the DU. The RRC reconfiguration command (RRCReconfiguration) may contain updated parameters related to the MAC and PHY layers and may be managed by RRC-L (for example, 6G mobility may be enhanced). After the handover is complete, it may be marked by the UE sending back a confirmation RRC reconfiguration complete (RRCreconfigurationComplete). RRC-L may send an indication of the new cell ID to which the UE has switched to the RRC-H layer. RRC-H may then decide whether the upper layer PDCP reconstruction should be triggered so that new security keys may be generated.

[0224] As another option in dual RRC, the interface between RRC-H and RRC-L may not exist. Therefore, the access and mobility management function (AMF) can directly contact RRC-H and RRC-L.

[0225] The following may apply to both single and dual RRC: In a variant, the completion of the handover and the new cell ID from the RRC-L may be indicated to the RRC-H based on a condition (e.g., a reporting condition). The condition may be, for example, that the new cell (target cell) is part of a cell group (already configured earlier by a higher layer). The cell group may be, for example, a cell located at the border of a DU area, or a mobility tracking area (a cell along a highway versus a cell in a pedestrian area, or a cell group with different frequency layers), thereby helping the higher layer to configure the UE as needed. Similarly, a condition may be that the UE has been handed over to a cell that is not a cell group that has been configured earlier by a higher layer. This alternative may be advantageous if the pre-configured cell group is small.

[0226] The condition can also be a cell change count threshold, helping higher layers to update security based on switching frequency rather than time. The condition (cell group, or cell switching count) can be configured to the layer in the network that handles cell switching, which can be the DU or MAC layer or RRC-L. In another example, the condition is configured to the UE using RRC, and the UE can notify the higher layer after completing the handover.

[0227] The architecture disclosed above (single RRC and dual RRC) can be applicable to all PHY layer deployments including dMMO, CA and inter-cell beam management, ICBM, etc. And, handover procedures such as CHO, DAPS and LTM can be applied together with the disclosed architecture.

[0228] Cell-free communication via dMMO can allow the removal of the sense of boundaries on the PHY layer via dMMO technology. In the cell-free concept of dMMO, the UE can be served by multiple cells. Before the handover occurs, the UE may have established some data connection with another cell other than the serving cell. dMMO can realize the cell-free concept because the cell may no longer be the criterion for deciding the handover.

[0229] In the following, it may be shown how the baseline may be used for the concept of a cell at the MAC, for example, for LTM and CHO.

[0230] Figure 7 An example message sequence chart showing an example of a method according to the fourth, fifth and sixth example aspects is shown. In this example, at step 712, UE 110 may send at least one measurement report (e.g., a layer 1 measurement report) to DU 140, which provides a serving cell 120 and a target cell 130 for UE 110, wherein the serving cell 120 and the target cell 130 share at least a protocol configuration of a radio resource control layer. In step 713, DU 140 determines whether UE 110 is to perform a handover to target cell 130 based on the at least one measurement report. In step 714, DU 140 sends an indication of a handover configuration for a handover of UE 110 to target cell 130 to UE 110 based on determining that UE 110 is to perform a handover, the indication of the handover being included in a MAC CE trigger for a cell change / activation with or without a CHO condition to UE 110. UE 110 may perform a handover according to the handover configuration based on receiving the indication of the handover configuration. In step 715, UE 110 transmits a completion indicator indicating completion of the handover. In step 717, DU 140 transmits a cell indicator indicating target cell 130 to CU 150 based on receiving the completion indicator. In step 718, CU 150 determines to perform a cell action (e.g., security key update or determining a handover configuration for layer 3 handover) based on the cell indicator.

[0231] Figure 7 The example may involve baseline mobility of a single RRC and may illustrate mobility within a DU using the disclosed architecture. For example:

[0232] For example, step 711: UE 110 connects to cell 1 (eg, serving cell).

[0233] For example, step 712: any measurement that may be sent to the DU MAC sublayer may be defined as an L1 measurement that is sent (e.g., at least one measurement report is sent). The UE beam used for the measurement may be indicated in the report. These measurement reports may be sent from the UE to the DU MAC sublayer.

[0234] For example, step 713: upon receiving the measurement report, the DU MAC sublayer may make a decision to switch cells.

[0235] For example, step 714: the DU may send a MAC-CE cell change trigger to the UE with or without a CHO condition. In the MAC-CE cell trigger, there may be an RRC parameter (e.g., handover parameter) containing all information for the PHY and MAC of the target cell. To simplify the interface, the MAC-CE command may contain a pre-configured "config-group ID" (e.g., an indication of a configuration group) and a config index (e.g., a configuration index), which may point to an RRC parameter containing all information for the PHY and MAC of the target cell.

[0236] For example, step 715: After applying all configurations on the UE side, the UE may send an ACK to the DU to signal the completion of the activation.

[0237] For example, step 716: the UE switches to cell 2 (eg, target cell).

[0238] For example, step 717: the DU notifies the CU of a new cell ID.

[0239] For example, step 718: The CU may use the new cell ID for statistical network optimization. Upon receiving the cell ID, it may trigger a security key update. If the UE is at a DU boundary, it may trigger an L3 HO. According to the example, the DU may detect (or determine) whether the UE is at a DU boundary and enable an indication [DU boundary: true] (e.g., boundary indication) to the RRC layer. If the measurement satisfies the conditions, the L3 HO may be triggered, an L3 report may be sent to the CU, and the CU may trigger the L3 HO. Upon receiving the cell ID and [DU boundary: true] from the DU, the CU may trigger an L3 HO to the UE based on the L3 measurement report. Knowing that the UE is at a cell boundary may help the CU prioritize L3 switching over cell switching during MAC switching.

[0240] Figure 8 An example message sequence chart of an example of a method according to the fourth, fifth and sixth example aspects is shown. In this example, in step 812, UE 110 may send at least one measurement report (e.g., a layer 1 measurement report) to DU 180, DU 180 providing a serving cell 160 and a target cell 170 for UE 110, wherein the serving cell 160 and the target cell 170 share at least a protocol configuration of a radio resource control (denoted as RRC-H) layer, for example, the serving cell 160 and the target cell 170 share RRC-H. DU 180 is a DU configured with a mobility radio resource control (labeled as RRC-L) layer. In step 813, DU 180 determines whether UE 110 is to perform a handover to the target cell 170 based on the at least one measurement report. In step 814, DU 180 sends an indication of a handover configuration for handover of UE 110 to target cell 170 to UE 110 based on determining that UE 110 is to perform handover, the indication of the handover being included in an RRC reconfiguration message (RRCreconfiguration) without using RACH and with or without a CHO condition. UE 110 may perform handover according to the handover configuration based on receiving the indication of the handover configuration. In step 815, UE 110 sends a completion indicator indicating completion of the handover. In step 817, DU 180 transmits a cell indicator indicating the target cell 170 to CU 190 based on receiving the completion indicator. In step 818, CU 190 determines to perform a cell action (e.g., security key update or determination of a handover configuration for layer 3 handover) based on the cell indicator.

[0241] Figure 8 An example may involve dual RRC baseline mobility. For example:

[0242] For example, step 811: UE 110 connects to cell 1 (eg, serving cell).

[0243] For example, step 812: Any measurement that may be sent (e.g., at least one measurement report is sent) to the DU RRC-L may be defined as an L1 measurement. The UE beam used for the measurement may be indicated in the report. These measurement reports may be sent from the UE to the RRC-L sublayer.

[0244] For example, step 813: upon receiving the measurement report, the RRC-L sublayer may decide to switch cells.

[0245] For example, step 814: with or without CHO conditions, RRC-L may send an RRC command "RRCReconfigurationWithoutRACH" to the UE. In the cell handover trigger, there may be an RRC parameter (e.g., handover parameter) containing all information for the PHY and MAC of the target cell. To simplify the interface, the RRC command "RRCReconfigurationWithoutRACH" may contain a pre-configured "config-group ID" (e.g., an indication of a configuration group) and a config index (e.g., a configuration index), which may point to an RRC parameter containing all information for the PHY and MAC of the target cell.

[0246] For example, step 815: when all configurations on the UE side are applied, the UE sends

[0247] RRC reconfiguration is completed (RRCReconfigComplete) to DU / RRC-L.

[0248] For example, step 816: the UE is connected to cell 2.

[0249] For example, step 817: RRC-L notifies RRC-H of the new cell ID (eg, the cell indicator of the target cell).

[0250] For example, step 818: RRC-H may use the new cell ID for statistical network optimization. Upon receiving the new cell ID, it may trigger a security key update. If the UE is at a DU boundary, it may trigger an L3HO. If the measurement satisfies the conditions, the L3HO may be event triggered, the L3 report may be current for the RRC-H, and the RRC-H may trigger the L3 HO. The DU may detect (or determine) whether the UE is at a DU boundary, and the RRC-L may enable an indication [DU boundary: true] (e.g., boundary indication) to the RRC-H. After receiving the new cell ID and [DU boundary: true] from the RRC-L, the RRC-H may trigger an L3 HO for the UE based on the L3 measurement report. Knowing that the UE is at a cell boundary may help the RRC-H to prioritize L3 handover over cell handover during MAC handover.

[0251] Fig. 9 An example message sequence chart showing an example of a method according to the fourth, fifth and sixth example aspects is shown. In this example, at step 912, UE 110 may send at least one measurement report (e.g., a layer 1 measurement report) to DU 180, which provides a serving cell 160 and a target cell 170 for UE 110, wherein the serving cell 160 and the target cell 170 share a protocol configuration of at least a radio resource control (labeled as RRC-H) layer. DU 180 is a DU configured with a mobility radio resource control (labeled as RRC-L) layer. In step 913, DU 180 determines whether UE 110 is to perform a handover to the target cell 170 based on the at least one measurement report. In step 914, DU 180 sends an indication of a handover configuration for a handover of UE 110 to the target cell 170 to UE 110 based on determining that UE 110 is to perform a handover, the indication of the handover being included in an RRC reconfiguration message (RRCReconfiguration) without using RACH and with or without a CHO condition. UE 110 may perform handover according to the handover configuration based on the received indication of the handover configuration. In step 915, UE 110 sends a completion indicator indicating completion of the handover, such as RRCReconfigurationComplete.

[0252] Fig. 9 An example may involve dual RRC baseline mobility. For example:

[0253] For example, step 911: UE connects to cell 1.

[0254] For example, step 912: Any measurement that may be sent to DU RRC-L may be defined as L1 measurement. The UE beam used for the measurement may be indicated in the report. These measurement reports may be sent from the UE to the RRC-L sublayer.

[0255] For example, step 913: upon receiving the measurement report, the RRC-L sublayer may make a decision to switch cells (eg, determine whether the device is to perform a handover to a target cell).

[0256] For example, step 914: with or without CHO conditions, RRC-L may send an RRC command "RRCReconfigurationWithoutRACH" to the UE. In this cell switching trigger, there may be an RRC parameter containing all information for the PHY and MAC of the target cell. To simplify the interface, the command may contain a pre-configured "config-group ID" and a configuration index, which may point to an RRC parameter containing all information for the PHY and MAC of the target cell.

[0257] For example, step 915: after applying all configurations on the UE side, the UE may send an RRC reconfiguration complete (RRCReconfigComplete) to the DU / RRC-L.

[0258] For example, step 916: the UE is connected to cell 2.

[0259] Fig.10An example message sequence chart showing an example of a method according to the fourth, fifth and sixth example aspects is shown. In this example, in step 1012, UE 110 may send at least one measurement report (e.g., a layer 1 measurement report) to DU 140, which provides a serving cell 120 and a target cell 130 for UE 110, wherein the serving cell 120 and the target cell 130 share a protocol configuration of at least a radio resource control layer. In step 1013, DU 140 determines whether UE 110 is to perform a handover to the target cell 130 based on the at least one measurement report. In step 1014, DU 140 sends an indication of a handover configuration for a handover of UE 110 to the target cell 130 to UE 110 based on determining that UE 110 is to perform a handover, the indication of the handover being included in a MAC CE trigger for a cell change / activation with or without a CHO condition to UE 110. UE 110 may perform a handover according to the handover configuration based on receiving the indication of the handover configuration. In step 1015, UE 110 sends a completion indicator indicating completion of the handover. In step 1017, UE 110 sends a cell indicator indicating target cell 130 to CU 150. In step 1018, CU 150 determines to perform a cell action (such as security key update or determining a handover configuration for layer 3 handover) based on the cell indicator.

[0260] Fig.10 The example may involve baseline mobility of a single RRC and may illustrate mobility within a DU using the disclosed architecture. For example:

[0261] For example, step 1011: the UE first connects to cell 1 (eg, serving cell).

[0262] For example, step 1012: any measurement that may be sent to the DU MAC sublayer may be defined as an L1 measurement that is sent (e.g., at least one measurement report is sent). The UE beam used for the measurement may be indicated in the report. These measurement reports may be sent from the UE to the DU MAC sublayer.

[0263] For example, step 1013: upon receiving the measurement report, the DU MAC sublayer may make a decision to switch cells.

[0264] For example, step 1014: For example, in a single RRC, the DU may send a MAC-CE cell handover command. In this cell handover trigger, there may be RRC parameters (e.g., handover parameters) containing all necessary information for the PHY and MAC of the target cell. To simplify the interface, this command may contain a pre-configured "config-group ID" (e.g., an indication of a configuration group) and a config index (e.g., a configuration index), which may point to an RRC parameter containing all necessary information for the PHY and MAC of the target cell.

[0265] For example, step 1015: When all necessary configurations are applied on the UE side, the UE may send an optional confirmation, such as in a single RRC case.

[0266] For example, step 1016: the UE is now connected to cell 2.

[0267] For example, step 1017: UE notifies CU of the new cell ID. Fig.10 In the example of , the UE may be configured to notify higher layers of the new cell ID.

[0268] For example, in step 1018 the CU may use the new cell ID for statistical network optimization. Upon receiving the cell ID, it may trigger a security key update. If the UE is at a DU boundary, it may trigger an L3 HO. According to the example, the DU may detect (or determine) whether the UE is at a DU boundary and enable an indication to the RRC layer [DU boundary: true] (e.g., a boundary indication). If the measurement satisfies the conditions, the L3HO may be triggered, the L3 report may be sent to the CU, and then the CU may trigger the L3 HO. After receiving the cell ID and [DU boundary: true] from the DU, the CU may trigger an L3HO for the UE based on the L3 measurement report. Knowing that the UE is at a cell boundary may help the CU prioritize L3 switching over cell switching during MAC switching.

[0269] Fig.11An example message sequence chart showing an example of a method according to the fourth, fifth and sixth example aspects is shown. In this example, in step 1112, UE 110 may send at least one measurement report (e.g., a layer 1 measurement report) to DU 180, DU 180 providing a serving cell 160 and a target cell 170 for UE 110, wherein the serving cell 160 and the target cell 170 share at least a protocol configuration of a radio resource control (denoted as RRC-H) layer, for example, the serving cell 160 and the target cell 170 share RRC-H. DU 180 is a DU configured with a mobility radio resource control (labeled as RRC-L) layer. In step 1113, DU 180 determines whether UE 110 is to perform a handover to the target cell 170 based on the at least one measurement report. In step 1114, DU 180 sends an indication of a handover configuration for handover of UE 110 to target cell 170 to UE 110 based on determining that UE 110 is to perform handover, the indication of the handover being included in an RRC reconfiguration message (RRCReconfiguration) without using RACH and with or without a CHO condition. UE 110 may perform handover according to the handover configuration based on receiving the indication of the handover configuration. In step 1115, UE 110 sends a completion indicator indicating completion of the handover, for example, RRC reconfiguration completion (RRCReconfigurationComplete). In step 1117, UE 110 sends a cell indicator indicating target cell 170 to CU 190. In step 1118, CU 190 determines to perform a cell action (such as security key update or determination of handover configuration for layer 3 handover) based on the cell indicator.

[0270] Fig.11 An example may involve dual RRC baseline mobility. For example:

[0271] For example, step 1111: the UE first connects to cell 1.

[0272] For example, step 1112: Any measurement that may be sent to DU RRC-L may be defined as L1 measurement. The UE beam used for the measurement may be indicated in the report. These measurement reports may be sent from the UE to the RRC-L sublayer.

[0273] For example, step 1113: upon receiving the measurement report, the RRC-L sublayer may make a decision to switch cells.

[0274] For example, step 1114: For example, in the dual RRC case, RRC-L may send an RRC command "RRCReconfigurationWithoutRACH" to the UE with or without a CHO condition. In the cell switching trigger, there may be RRC parameters (e.g., switching parameters) that contain all necessary information for the PHY and MAC of the new target cell. To simplify the interface, the command may contain a pre-configured "config-group ID" and a configuration index that may point to the RRC parameters containing all necessary information for the PHY and MAC of the new target cell.

[0275] For example, step 1115: When all necessary configurations are applied on the UE side, the UE may send an RRC Reconfiguration Complete to the DU / RRC-L in the dual RRC case.

[0276] For example, step 1116: the UE is now connected to cell 2.

[0277] For example, step 1117: the UE may notify the RRC-H of the new cell ID. Fig.11 In the example of , the UE may be configured to notify higher layers of the new cell ID.

[0278] For example, in step 1118, the RRC-H may use the new cell ID for statistical network optimization. Upon receiving the new cell ID, it may trigger a security key update. If the UE is at a DU boundary, it may trigger an L3 HO. If the measurement satisfies the conditions, the L3 HO may be event triggered, an L3 report may be sent to the RRC-H, and the RRC-H may trigger the L3 HO. The DU may detect (or determine) whether the UE is at a DU boundary, and the RRC-L may enable an indication [DU boundary: true] (e.g., boundary indication) to the RRC-H. After receiving the new cell ID and [DU boundary: true] from the RRC-L, the RRC-H may trigger an L3 HO for the UE based on the L3 measurement report. Knowing that the UE is at a cell boundary may help the RRC-H prioritize L3 switching over cell switching during MAC switching.

[0279] Fig.12An example message sequence chart of an example of a method according to the fourth, fifth and sixth example aspects is shown. In this example, in step 1212, UE 110 may send at least one measurement report (e.g., a layer 1 measurement report) to DU 180, which provides a serving cell 160 and a target cell 170 for UE 110, wherein the serving cell 160 and the target cell 170 share at least a protocol configuration of a radio resource control (denoted as RRC-H) layer, for example. The serving cell 160 and the target cell 170 share RRC-H. DU 180 is a DU configured with a mobility radio resource control (labeled as RRC-L) layer. In step 1213, DU 180 determines whether UE 110 is to perform a handover to the target cell 170 based on the at least one measurement report. In step 1214, DU 180 transmits an indication of a handover configuration for a handover of UE 110 to the target cell 170 based on determining that UE 110 is to perform a handover. The indication of the handover may be included in an RRC reconfiguration message (RRCReconfiguration). The RRC reconfiguration may be, for example, an RRC reconfiguration with synchronization and with or without a CHO condition. In step 1215, the UE 110 may perform a random access channel (RACH) process with the target cell 170 based on receiving a synchronized RRC reconfiguration message including an indication of the handover configuration to perform the handover according to the handover configuration. In step 1216, the UE 110 sends a completion indicator indicating the completion of the RACH process or handover, the completion indicator being, for example. RRC reconfiguration is complete. In step 1219, the UE 110 may, for example, send a cell indicator indicating the target cell to the DU / RRC-H. Alternatively or additionally, in step 1222, the DU 180 may, for example, send a cell indicator indicating the target cell to the DU / RRC-H. In step 1220 , or alternatively / additionally ( 1218 , 1221 ), in step 1223 , the CU 190 determines to perform a cell action (such as a security key update or determining a handover configuration for a layer 3 handover) based on the cell indicator.

[0280] Fig.12 Examples may involve baseline mobility of dual RRC. For example, the illustrated RRC-L may also trigger RACH for handover, and the disclosed architecture may allow updating of the cell ID from the DU or UE to the CU, which may enable separate security key update or separate reestablishment of the PDCP and RLC layers.

[0281] The following examples are also disclosed (particularly with respect to methods according to any aspect):

[0282] The serving DU triggers a cell change via a new MAC CE containing updated parameters involving only PHY and MAC. With single and dual RRC options, the serving DU forwards the new Cell ID IE to the CU. With the UE option, the Cell ID is forwarded by the UE to higher layers. The serving CU decides to trigger PDCP re-establishment, update security keys or configure L3 handover.

[0283] The following examples are also disclosed (particularly with respect to methods according to any aspect):

[0284] For each UE, one RRC entity is created for the current serving cell to set all parameters for PDPC, RLC, MAC and PHY.

[0285] When the UE moves across cells within a DU, the change of serving cell is activated by the MAC-CE based on measurement report DU reception.

[0286] Instead of reconfiguring the entire set, such a trigger may include (e.g., only) updated parameters related to PHY and MAC. (Incremental reconfiguration)

[0287] When the HO is completed, the DU sends an indication of the new cell ID to which the UE is handed over to the RRC layer.

[0288] This indication causes PDCP to re-establish, thereby generating new security keys.

[0289] This example may involve single RRC, dual RRC or UE driven.

[0290] Example 1. Single RRC at CU:

[0291] When the UE moves across cells within a DU, based on the reception of measurement reports at the DU, a change of serving cell may be activated by a MAC-CE containing updated parameters related to the MAC and PHY layers.

[0292] Once the handover is complete (which can be marked by the UE sending back an acknowledgement), the MAC layer at the DU can inform the RRC layer at the CU of the new cell ID. The RRC can then decide whether to trigger an upper layer PDCP re-establishment to generate new security keys.

[0293] Example 2. Dual RRC (RRC split: RRC-H at CU, RRC-L at DU):

[0294] When the UE moves across cells within a DU, based on the measurement reports received at the DU RRC-L, the change of serving cell may be activated by an RRC reconfiguration command containing updated parameters related to the MAC and PHY layers and may be managed by the RRC-L.

[0295] Once the handover is complete (which can be confirmed by the UE sending back an RRC reconfiguration complete flag (RRCReconfigurationComplete)), RRC-L can inform the RRC-H of the new cell ID. RRC-H can then decide whether to trigger an upper layer PDCP reestablishment to generate new security keys.

[0296] Furthermore, the described steps may, for example, be based on a condition (eg, a reporting condition), such as the new cell being part of a cell group.

[0297] Example 3. UE notifies higher layers:

[0298] In both single RRC and dual RRC cases, the UE may inform the CU of the new cell ID.

[0299] Fig.13 is a schematic block diagram of an example embodiment of an apparatus according to the first aspect and / or an example embodiment of a distributed unit of a network entity according to the second aspect and / or an example embodiment of a central unit of a network entity according to the third example aspect.

[0300] The device, distributed unit or central unit 900 comprises a processor 901 , a program memory 902 , a working or main memory 903 , a data memory, a communication interface 904 and an optional user interface 905 .

[0301] The device, distributed unit or central unit 900 may be configured to perform and / or control or include corresponding components (at least one of 901 to 905) for performing and / or controlling the method according to the fourth, fifth and / or sixth exemplary aspects. The device, distributed unit or central unit 900 may also constitute a device, distributed unit or central unit comprising at least one processor (901) and at least one memory (902) storing instructions, which when executed by the at least one processor causes the device or network entity, for example. The device, distributed unit or central unit 900 performs and / or controls the method according to at least all (corresponding) exemplary aspects.

[0302] The processor 901 may, for example, further control memories 902 to 903 , communication interface(s) 904 , an optional user interface 905 .

[0303] The processor 901 may for example execute program code stored in a program memory 902 , which may for example represent a readable storage medium comprising program code which, when executed by the processor 901 , causes the processor 901 to perform a method according to the fourth, fifth or sixth example aspect.

[0304] Processor 901 (and any other processors mentioned in this specification) can be any suitable type of processor. Processor 901 may include, but is not limited to, one or more microprocessors, one or more processors with one or more digital signal processors, one or more processors without digital signal processors, one or more special-purpose computer chips, one or more field programmable gate arrays (FPGAs), one or more controllers, one or more application-specific integrated circuits (ASICs), or one or more computers / servers. The relevant structure / hardware has been programmed to perform the described functions. Processor 1001 may, for example, be an application processor running an operating system.

[0305] A program memory 902 may also be included in the processor 901. The memory may, for example, be fixedly connected to the processor 901 or at least partially removable from the processor 901, for example in the form of a memory card or stick. The program memory 902 may, for example, be a non-volatile memory. For example, it may be any of a FLASH memory (or a portion thereof), a ROM, a PROM, an EPROM and an EEPROM memory (or a portion thereof) or a hard disk (or a portion thereof), to name just a few examples. The program memory 902 may also include an operating system for the processor 901. The program memory 902 may also include firmware for the device or network entity 900.

[0306] The communication interface 904 enables the device or network entity 900 to communicate with other entities, for example, another device or network entity. The communication interface 904 may include, for example, a wireless interface, such as a cellular radio communication interface and / or a WLAN interface) and / or a wired interface interface, an IP-based interface, such as for communicating with an entity via the Internet. The communication interface may enable the device or network entity 900 to communicate with other entities, such as one or more entities included in a mobile communication network.

[0307] User interface 905 is optional and may include a display for displaying information to a user and / or an input device (eg, a keyboard, keypad, touch pad, mouse, etc.) for receiving information from a user.

[0308] Some or all of the components of the device or network entity 900 may be connected, for example, via a bus. Some or all of the components of the device or network entity 900 may be combined into one or more modules, for example.

[0309] The device 900 may also include at least one of the following: a receiver, for example, for receiving an indication of a switching configuration for switching the device to the target cell; a transmitter, for example, for sending at least one measurement report; a determiner, for example, for determining whether the switching is completed; a reconstructor; or an executor.

[0310] The distributed unit 900 may also include at least one of the following: a provider, for example, providing a service cell and a target cell for the device; a transmitter, for example, sending an indication of a switching configuration for switching the device to the target cell; a determiner, for example, for determining whether the device is to perform a switch to the target cell; or a receiver, for example, for receiving at least one measurement report.

[0311] The central unit 900 may further include at least one of the following: a receiver, for example, for receiving a cell indicator indicating a target cell; a determiner, for example, for determining to perform a cell action; and a transmitter, for example, for sending a key indication.

[0312] Fig.14 For example, it can be used to implement Fig.13 902 or memory 903 of the present disclosure according to an example of a (tangible and / or non-transitory) computer-readable storage medium. To this end, Fig.14 Shown is a flash memory 1000 which may be, for example, soldered or glued to a printed circuit board, a solid-state drive 1001 comprising a plurality of memory chips (e.g., flash memory chips), a magnetic hard disk drive 1002, a secure digital (SD) card 1003, a universal serial bus (USB) memory stick 1004, an optical storage medium 1005 (e.g., a CD-ROM or DVD), and a magnetic storage medium 1006.

[0313] In this specification, any connection presented in the described embodiments will be understood as the components involved being operatively coupled. Therefore, the connection may be direct or indirect with any number of intermediate elements or combinations of intermediate elements, and there may only be a functional relationship between the components.

[0314] In addition, any of the methods, processes, and actions described or illustrated herein may be implemented using executable instructions in a general or special purpose processor and stored on a computer-readable storage medium (e.g., disk, memory, etc.) for execution by such a processor. References to 'computer-readable storage medium' should be understood to include special purpose circuits such as FPGAs, ASICs, signal processing devices, and other devices.

[0315] The expression "A and / or B" is considered to include any of the following three situations: (i) A, (ii) B, (iii) A and B. In addition, the article "a" should not be understood as "one", that is, the use of the expression "element" does not exclude the presence of additional elements. The term "comprising" should be understood as an open-ended meaning, that is, an object "comprising element A" may include other elements in addition to element A. In addition, the term "comprising" may be limited to "consisting of", that is, consisting of only the specified elements.

[0316] The expressions “at least one of: ” and “” and similar expressions (wherein a list of two or more elements is connected by “and” or “or”) refer to at least any one of these elements, or at least any two or more of these elements, or at least all of these elements.

[0317] It will be understood that all presented embodiments are examples only, and any feature presented for a particular example embodiment may be used with any aspect alone or in combination with any feature presented for the same or another particular example embodiment and / or in combination with any other feature not mentioned. Specifically, the example embodiments given in this specification should also be understood to be disclosed in all possible combinations with each other, as long as they are technically reasonable and the example embodiments are not substitutes for each other. It should also be understood that any feature given for example embodiments in a particular category (method / device / computer program / system) may also be used in a corresponding manner in example embodiments of any other category. It should also be understood that the presence of a feature in a given example embodiment does not necessarily mean that the feature forms a necessary feature and cannot be omitted or replaced.

[0318] The statement that a feature comprises at least one subsequently listed feature does not necessarily require that the feature comprises all subsequently listed features or comprises at least one feature of a plurality of subsequently listed features. Furthermore, the listed features may be selected in any combination or only one of the listed features may be selected. Specific combinations of all subsequently listed features are also conceivable. Furthermore, a plurality of listed features may be present or only one listed feature may be present.

[0319] The sequence of all method steps presented above is not mandatory, and alternative sequences are also possible. However, the specific sequence of method steps shown by way of example in the drawings should be considered as one possible sequence of method steps for the respective embodiments described by the respective drawings.

[0320] The present subject matter has been described above by way of example. It should be noted that there are alternatives and variations that are obvious to those skilled in the art and that can be implemented without departing from the scope of the appended claims.

[0321] This disclosure provides the following examples.

[0322] Example 1. A device, comprising: a component for sending at least one measurement report to a network entity, the network entity providing a service cell and a target cell for the device, wherein the service cell and the target cell at least share a protocol configuration of a radio resource control layer; a component for receiving an indication of a switching configuration for switching the device to the target cell from the network entity; and a component for performing the switching according to the switching configuration based on the received indication of the switching configuration.

[0323] Example 2. The apparatus of Example 1, wherein the indication of the switch indicates at least one of: a configuration group or a configuration index.

[0324] Example 3. An apparatus according to Example 1 or 2, wherein the switching configuration includes switching parameters for layers that are not shared between the serving cell and the target cell, and wherein performing the switching according to the switching configuration includes reconfiguring the layers that are not shared between the serving cell and the target cell based on the switching parameters.

[0325] Example 4. An apparatus according to any one of Examples 1 to 3, wherein the switching configuration includes switching parameters only for layer 2 and layer 1, and wherein performing the switching according to the switching configuration includes reconfiguring layer 1 and layer 2 based on the switching configuration.

[0326] Example 5. An apparatus according to any one of Examples 1 to 4, wherein the serving cell and the target cell are managed at layer 2.

[0327] Example 6. An apparatus according to any one of Examples 1 to 5, wherein the serving cell and the target cell further share at least one of a packet data convergence protocol layer or a radio link control layer.

[0328] Example 7. The apparatus according to any one of Examples 1 to 6 further includes: a component for sending a completion indicator indicating completion of the handover to the network entity based on completion of the handover.

[0329] Example 8. The apparatus according to any one of Examples 1 to 7 further includes: a component for receiving a key indication indicating a security key from the network entity after performing the switching; and a component for generating the security key based on the key indication.

[0330] Example 9. The apparatus according to any one of Examples 1 to 8 further includes: a component for receiving a reconstruction indication including an indication of configuration parameters for a layer from the network entity after performing the switching; and a component for reconstructing the layer based on the reconstruction indication.

[0331] Example 10. The apparatus according to any one of Examples 1 to 9 further includes: a component for receiving a switching configuration from the network entity after performing the switching, the switching configuration being for a layer 3 switching to a cell provided by another network entity or a layer 3 switching to a cell provided by a distributed unit that does not provide the service cell; and a component for performing the layer 3 switching based on receiving the switching configuration for the layer 3 switching.

[0332] Example 11. The apparatus according to any one of Examples 1 to 10 further includes: a component for determining whether the handover is completed; and a component for sending a cell indicator indicating the target cell to a central unit of the network entity based on determining that the handover is completed.

[0333] Example 12. The apparatus of Example 11, further comprising: means for receiving a reporting condition from the network entity, wherein the sending the cell indicator is performed based on determining that the reporting condition is met.

[0334] Example 13. A distributed unit of a network entity, comprising: a component for providing a service cell and a target cell for a device, wherein the service cell and the target cell at least share a protocol configuration of a radio resource control layer; a component for receiving at least one measurement report from the device; a component for determining whether the device is to perform a handover to the target cell based on the at least one measurement report; and a component for sending an indication of a handover configuration for the handover of the device to the target cell to the device based on determining that the device is to perform the handover.

[0335] Example 14. A distributed unit according to Example 13, wherein the determining whether the device is to perform the handover is performed in layer 2, specifically in a media access control layer.

[0336] Example 15. The distributed unit of Example 13, wherein the determining whether the device is to perform the handover is performed in a mobility radio resource control layer, wherein the mobility radio resource control layer is a radio resource control layer utilized by the distributed unit.

[0337] Example 16. The distributed unit according to any one of Examples 13 to 15 further includes: a component for determining whether the switching is completed; and a component for sending a cell indicator indicating the target cell to the central unit of the network entity based on determining that the switching is completed.

[0338] Example 17. The distributed unit of Example 16, wherein the sending the cell indicator is performed based on determining that a reporting condition is met.

[0339] Example 18. A distributed unit according to Example 16 or 17, comprising means for receiving a completion indicator from the device indicating completion of the handover based on sending the indication of the handover, wherein the sending the cell indicator is based on receiving the completion indicator.

[0340] Example 19. A distributed unit according to any one of Examples 13 to 18, wherein the indication of the switching indicates at least one of the following: a configuration group or a configuration index.

[0341] Example 20. A distributed unit according to any one of Examples 13 to 19, wherein the handover configuration includes handover parameters for layers that are not shared between the serving cell and the target cell.

[0342] Example 21. A distributed unit according to any one of Examples 13 to 20, wherein the switching configuration includes switching parameters for layer 2 and layer 1 only.

[0343] Example 22. A distributed unit according to any one of Examples 13 to 21, further comprising: a component for determining whether the device is located at a boundary of an area covered by a cell provided by the distributed unit; and a component for sending a boundary indication to a central unit of the network entity based on determining that the device is located at the boundary, wherein the boundary indication indicates that the device is located at the boundary of the area covered by the cell provided by the distributed unit.

[0344] Example 23. A distributed unit according to any one of Examples 13 to 22, wherein the serving cell and the target cell are managed on layer 2.

[0345] Example 24. A central unit of a network entity, comprising: a component for receiving a cell indicator indicating a target cell from a distributed unit or device of the network entity, the target cell and the serving cell being provided to the device by the distributed unit of the network entity, wherein the serving cell and the target cell at least share a protocol configuration of a radio resource control layer; and a component for determining to perform a cell action based on the cell indicator.

[0346] Example 25. The central unit of Example 24, wherein the cell action comprises a security key update, the central unit further comprising means for sending a key indication indicating a security key to the device based on determining to perform the security key update.

[0347] Example 26. A central unit according to Example 24 or 25, wherein the cell action includes layer reconstruction of a layer, and the central unit further includes: a component for sending a reconstruction indication to the device based on determining to perform the layer reconstruction, the reconstruction indication including an indication of configuration parameters for the layer; and a component for reconstructing the layer based on the configuration parameters of the layer.

[0348] Example 27. A central unit according to any one of Examples 24 to 26, wherein the cell action includes determining a switching configuration, the switching configuration being for a layer 3 switching to a cell provided by another network entity or to a cell provided by another distributed unit of the network entity, the central unit further comprising: a component for determining the switching configuration for the layer 3 switching based on determining to perform the cell action based on the cell indicator; and a component for sending the switching configuration for the layer 3 switching to the device.

[0349] Example 28. The central unit of Example 27, wherein determining the handover configuration for the layer 3 handover is based on the device being located at a boundary of an area covered by the cell provided by the distributed unit.

[0350] Example 29. The central unit according to Example 27 or 28 further includes: a component for receiving a boundary indication from the distributed unit, wherein the boundary indication indicates that the device is located at the boundary of the area covered by the cell provided by the distributed unit; wherein the determination of the switching configuration for the layer 3 switching is based on the boundary indication.

[0351] Example 30. A central unit according to any one of Examples 24 to 29, wherein the cell action includes determining a reporting condition, and the central unit further includes: a component for determining the reporting condition based on determining that the cell action is performed based on the cell indicator; and a component for sending the reporting condition to the device or the distributed unit.

[0352] Example 31. The central unit of any one of Examples 24 to 30, further comprising: means for maintaining a configuration of at least one of a packet data convergence protocol layer or a radio link control layer.

[0353] Example 32. The central unit of any one of Examples 24 to 31, wherein the serving cell and the target cell are managed at layer 2.

[0354] Example 33. An apparatus according to any one of Examples 1 to 12, a distributed unit according to any one of Examples 13 to 23, or a central unit according to any one of Examples 24 to 32, wherein the apparatus is a user device or is included in a user device.

[0355] Example 34. A method performed by a device, comprising: sending at least one measurement report to a network entity, the network entity providing a service cell and a target cell for the device, wherein the service cell and the target cell at least share a protocol configuration of a radio resource control layer; receiving from the network entity an indication of a switching configuration for switching the device to the target cell; and based on the received indication of the switching configuration, performing the switching according to the switching configuration.

[0356] Example 35. The method of Example 34, wherein the indication of the switching indicates at least one of: a configuration group or a configuration index.

[0357] Example 36. A method according to Example 34 or 35, wherein the handover configuration includes handover parameters for layers that are not shared between the serving cell and the target cell, and wherein performing the handover according to the handover configuration includes reconfiguring the layers that are not shared between the serving cell and the target cell based on the handover parameters.

[0358] Example 37. A method according to any one of Examples 34 to 36, wherein the switching configuration includes switching parameters only for layer 2 and layer 1, and wherein performing the switching according to the switching configuration includes reconfiguring layer 1 and layer 2 based on the switching configuration.

[0359] Example 38. A method according to any one of Examples 34 to 37, wherein the serving cell and the target cell are managed at layer 2.

[0360] Example 39. A method according to any one of Examples 34 to 38, wherein the serving cell and the target cell also share at least one of a packet data convergence protocol layer or a radio link control layer.

[0361] Example 40. The method according to any one of Examples 34 to 39 further includes: based on completing the switching, sending a completion indicator indicating the completion of the switching to the network entity.

[0362] Example 41. The method according to any one of Examples 34 to 40 further includes: after performing the switching, receiving a key indication indicating a security key from the network entity; and generating the security key based on the key indication.

[0363] Example 42. The method according to any one of Examples 34 to 41 further includes: after performing the switching, receiving a reconstruction indication including an indication of configuration parameters for a layer from the network entity; and reconstructing the layer based on the reconstruction indication.

[0364] Example 43. The method according to any one of Examples 34 to 42 further includes: after performing the switching, receiving a switching configuration from the network entity, the switching configuration being for a layer 3 switching to a cell provided by another network entity or a layer 3 switching to a cell provided by a distributed unit that does not provide the service cell; and performing the layer 3 switching based on receiving the switching configuration for the layer 3 switching.

[0365] Example 44. The method according to any one of Examples 34 to 43 further includes: determining whether the handover is completed; and based on determining that the handover is completed, sending a cell indicator indicating the target cell to a central unit of the network entity.

[0366] Example 45. The method of Example 44, further comprising: receiving a reporting condition from the network entity, wherein sending the cell indicator is performed based on determining that the reporting condition is met.

[0367] Example 46. A method performed by a distributed unit of a network entity, comprising: providing a service cell and a target cell for a device, wherein the service cell and the target cell share at least a protocol configuration of a radio resource control layer; receiving at least one measurement report from the device; determining whether the device is to perform a handover to the target cell based on the at least one measurement report; and sending an indication of a handover configuration for the handover of the device to the target cell to the device based on determining that the device will perform the handover.

[0368] Example 47. The method of Example 46, wherein the determining whether the device is to perform the handover is performed in layer 2, specifically in a media access control layer.

[0369] Example 48. The method of Example 46, wherein the determining whether the device is to perform the handover is performed in a mobility radio resource control layer, wherein the mobility radio resource control layer is a radio resource control layer utilized by the distributed unit.

[0370] Example 49. The method according to any one of Examples 46 to 48 further includes: determining whether the handover is completed; and based on determining that the handover is completed, sending a cell indicator indicating the target cell to a central unit of the network entity.

[0371] Example 50. The method of Example 49, wherein the sending the cell indicator is performed based on determining that a reporting condition is satisfied.

[0372] Example 51. The method of Example 49 or 50, based on transmitting the indication of the handover, receiving a completion indicator from the device indicating completion of the handover, wherein the sending the cell indicator is based on receiving the completion indicator.

[0373] Example 52. A method according to any one of Examples 46 to 51, wherein the indication of the switching indicates at least one of: a configuration group or a configuration index.

[0374] Example 53. A method according to any one of Examples 46 to 52, wherein the handover configuration includes handover parameters for layers that are not shared between the serving cell and the target cell.

[0375] Example 54. A method according to any one of Examples 46 to 53, wherein the handover configuration includes handover parameters only for layer 2 and layer 1.

[0376] Example 55. The method according to any one of Examples 46 to 54 further includes: determining whether the device is located at the boundary of the area covered by the cell provided by the distributed unit; based on determining that the device is located at the boundary, sending a boundary indication to the central unit of the network entity, wherein the boundary indication indicates that the device is located at the boundary of the area covered by the cell provided by the distributed unit.

[0377] Example 56. A method according to any one of Examples 46 to 55, wherein the serving cell and the target cell are managed at Layer 2.

[0378] Example 57. A method performed by a central unit of a network entity, comprising: receiving a cell indicator indicating a target cell from a distributed unit or device of the network entity, the target cell and the serving cell being provided to the device by the distributed unit of the network entity, wherein the serving cell and the target cell at least share a protocol configuration of a radio resource control layer; and determining to perform a cell action based on the cell indicator.

[0379] Example 58. The method of Example 57, wherein the cell action comprises a security key update, the method further comprising: based on determining to perform the security key update, sending a key indication indicating a security key to the device.

[0380] Example 59. A method according to Example 57 or 58, wherein the cell action includes layer reconstruction of a layer, the method further comprising: based on determining to perform the layer reconstruction, sending a reconstruction to the device, the reconstruction indication including an indication of configuration parameters for the layer; and reconstructing the layer based on the configuration parameters of the layer.

[0381] Example 60. A method according to any one of Examples 57 to 59, wherein the cell action includes determining a switching configuration, the switching configuration being for a layer 3 switching to a cell provided by another network entity or to a cell provided by another distributed unit of the network entity, the method further comprising: determining the switching configuration for the layer 3 switching based on determining that the cell action is performed based on the cell indicator; and sending the switching configuration for the layer 3 switching to the device.

[0382] Example 61. The method of Example 60, wherein determining the handover configuration for the layer 3 handover is based on the device being located at a boundary of an area covered by the cell provided by the distributed unit.

[0383] Example 62. The method according to Example 60 or 61 further includes: receiving a boundary indication from the distributed unit, the boundary indication indicating that the device is located at the boundary of the area covered by the cell provided by the distributed unit; wherein the determination of the switching configuration for the layer 3 switching is based on the boundary indication.

[0384] Example 63. A method according to any one of Examples 57 to 62, wherein the cell action includes determining a reporting condition, and the method further includes: determining the reporting condition based on determining that the cell action is performed based on the cell indicator; and sending the reporting condition to the device or the distributed unit.

[0385] Example 64. The method of any one of Examples 57 to 63 further includes maintaining a configuration of at least one of a packet data convergence protocol layer or a radio link control layer.

[0386] Example 65. A method according to any one of Examples 57 to 64, wherein the serving cell and the target cell are managed on Layer 2.

[0387] Example 66. A method according to any one of Examples 34 to 64, wherein the device is a user equipment or is included in a user equipment.

[0388] Example 67. A system comprising an apparatus according to any one of Examples 1 to 12, wherein the apparatus is a user equipment or a mobile entity, at least one distributed unit of a network entity according to any one of Examples 13 to 23, and a central unit according to any one of Examples 24 to 33, jointly performing a method according to any one of Examples 34 to 64.

[0389] Example 68. A computer program product which, when executed by a processor of an apparatus, causes the apparatus to perform a method according to any one of Examples 34 to 64.

[0390] Example 69. A computer program which, when executed by a processor, causes a device to perform or control the actions of a method according to any one of Examples 34 to 64.

[0391] Example 70. A tangible and non-transitory storage medium comprising a computer program product according to Example 68 or a computer program according to Example 69.

[0392] List of abbreviations:

[0393] 3GPP Third Generation Partnership Project

[0394] 5G 5th Generation

[0395] AM Confirmation Mode

[0396] BS Base Station

[0397] CA Carrier Aggregation

[0398] CU Central Unit

[0399] DL Downlink

[0400] dMMO distributed multiple input multiple output

[0401] DU Distributed Unit

[0402] DRB Data Radio Bearer EHC Ethernet Header Compression gNB Next Generation Base Station

[0403] ICBM Inter-cell Beam Management IP Internet Protocol

[0404] L1 Layer 1 L2 Layer 2 L3 Layer 3 MAC Media / MAC MIMO MIMO NR New Radio

[0405] PDCP Packet Data Convergence Protocol PDSCH Physical Downlink Shared Data Channel PUSCH Physical Uplink Shared Data Channel RACH Random Access Channel RAN Radio Access Network RF Radio Frequency

[0406] ROHC RObust Header Compression RLC Radio Link Control RRC Radio Resource Control SDAP Service Data Adaptation Protocol SDU Service Data Unit SRB Signaling Radio Bearer UDC Uplink Data Compression UE User Equipment

[0407] UL Uplink

[0408] UM Unconfirmed Mode

Claims

1. A device comprising: means for sending at least one measurement report to a network entity providing a serving cell and a target cell for the apparatus, wherein the serving cell and the target cell share at least a protocol configuration of a radio resource control layer; means for receiving, from the network entity, an indication of a handover configuration for handover of the apparatus to the target cell; Means for performing the handover in accordance with the handover configuration based on receiving the indication of the handover configuration. 2 . The apparatus of claim 1 , wherein the indication of the switching indicates at least one of: a configuration group or a configuration index.

3. An apparatus according to claim 1 or 2, wherein the switching configuration includes switching parameters for layers that are not shared between the serving cell and the target cell, and wherein performing the switching according to the switching configuration includes reconfiguring the layers that are not shared between the serving cell and the target cell based on the switching parameters. 4 . The apparatus according to claim 1 , wherein the handover configuration comprises handover parameters only for layer 2 and layer 1 , and wherein performing the handover according to the handover configuration comprises reconfiguring layer 1 and layer 2 based on the handover configuration. 5 . The apparatus according to claim 1 , wherein the serving cell and the target cell are managed at layer 2. 6 . 6 . The apparatus according to claim 1 , wherein the serving cell and the target cell further share at least one of a packet data convergence protocol layer or a radio link control layer.

7. The device according to claim 1 or 2, further comprising: means for sending a completion indicator to the network entity indicating completion of the handover based on completing the handover.

8. The device according to claim 1 or 2, further comprising: means for receiving a key indication indicating a security key from the network entity after performing the handover; Means for generating the security key based on the key indication.

9. The device according to claim 1 or 2, further comprising: means for receiving, from said network entity, a reestablishment indication including an indication of configuration parameters for a layer after performing said handover; Means for reconstructing the layer based on the reconstruction indication.

10. The device according to claim 1 or 2, further comprising: means for receiving a handover configuration from the network entity after performing the handover, the handover configuration being for a layer 3 handover to a cell provided by another network entity or to a layer 3 handover to a cell provided by a distributed unit that does not provide the serving cell; Means for performing the layer 3 handover based on receiving the handover configuration for the layer 3 handover.

Images