Data transmission using data radio bearers

Abstract

A user equipment (UE) comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least perform: receiving downlink signaling, the downlink signaling providing a first data radio bearer (DRB) configuration for a cell, and a second data radio bearer (DRB) configuration for the cell; storing a first data radio bearer configuration for performing data transmission via the cell using the first data radio bearer, and storing a second data radio bearer configuration for performing data transmission via the cell using the second data radio bearer; receiving a trigger; and in response to the received trigger, performing data transmission between the user equipment and the cell using the first data radio bearer configuration if the trigger indicates use of the first data radio bearer configuration, and performing data transmission between the user equipment and the cell using the second data radio bearer configuration if the trigger indicates use of the second data radio bearer configuration. If so, data transmission is performed between the user equipment and the cell using the second data radio bearer configuration.

Description

Technical Field

[0001] Examples of the present disclosure relate to data transmission using data radio bearers.

[0002] Examples of the present disclosure relate to data transmission using data radio bearers of a third generation partnership cellular radio telecommunication network. Background Art

[0003] A data radio bearer represents a transport channel for data. For example, a data radio bearer is used to transmit data via a radio interface in a radio telecommunication network. The radio interface is the interface between a user equipment and a base station serving one or more cells of a cellular radio telecommunication network.

[0004] Cellular radio telecommunication networks require that user equipment be able to handover from one cell to another.

[0005] Configuration of data radio bearers requires signaling and takes time. Summary of the Invention

[0006] The inventors have recognized that, depending on the implementation, configuration of data radio bearers in existing systems may use up time and resources in anticipation of, during, and / or after a handover.

[0007] According to various, but not necessarily exhaustive, examples are provided as claimed in the independent claims, for example:

[0008] A user equipment UE includes:

[0009] at least one processor; and

[0010] At least one memory storing instructions, which, when executed by the at least one processor, cause the UE to at least perform:

[0011] receiving downlink signaling providing a first data radio bearer (DRB) configuration for the cell and a second data radio bearer (DRB) configuration for the cell;

[0012] storing a first data radio bearer configuration for performing data transmission via the cell using the first data radio bearer, and storing a second data radio bearer configuration for performing data transmission via the cell using the second data radio bearer;

[0013] receiving a trigger; and

[0014] In response to the received trigger,

[0015] If the trigger indicates use of the first data radio bearer configuration, performing data transmission between the user equipment and the cell using the first data radio bearer configuration, and

[0016] If the trigger indicates use of the second data radio bearer configuration, data transmission is performed between the user equipment and the cell using the second data radio bearer configuration.

[0017] and / or, a method comprising:

[0018] receiving downlink signaling providing a first data radio bearer (DRB) configuration for the cell and a second data radio bearer (DRB) configuration for the cell;

[0019] storing a first data radio bearer configuration for performing data transmission via the cell using the first data radio bearer, and storing a second data radio bearer configuration for performing data transmission via the cell using the second data radio bearer;

[0020] Receive trigger;

[0021] If the trigger indicates use of the first data radio bearer configuration, performing data transmission between the user equipment and the cell using the first data radio bearer configuration, and

[0022] If the trigger indicates use of the second data radio bearer configuration, data transmission is performed between the user equipment and the cell using the second data radio bearer configuration.

[0023] and / or, a computer program for a user equipment, comprising instructions, which when executed on a computer, execute: conditionally performing data transmission between the user equipment and a cell, wherein

[0024] if the trigger indicates use of a previously received and stored first data radio bearer configuration, causing data transmission to be performed between the user equipment and the cell using the first data radio bearer configuration, and

[0025] If the trigger indicates use of a previously received and stored second data radio bearer configuration, data transmission is caused to be performed between the user equipment and the cell using the second data radio bearer configuration.

[0026] And / or, an apparatus for a radio access network, comprising:

[0027] at least one processor; and

[0028] at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least:

[0029] causing transmission of downlink signaling to a user equipment, the downlink signaling providing a first data radio bearer configuration for the cell and a second data radio bearer configuration for the cell;

[0030] Causes a trigger to be transmitted to the user equipment, the trigger

[0031] configured to indicate use of a first data radio bearer configuration to enable data transmission between the user equipment and the cell using the first data radio bearer,

[0032] is configured to indicate use of a second data radio bearer configuration to enable data transmission between the user equipment and the cell using the second data radio bearer.

[0033] According to various, but not necessarily exhaustive, examples are provided as claimed in the appended claims, for example:

[0034] An apparatus (user equipment) wherein the control circuitry is configured to switch a data transmission session between transmission using a first data radio bearer configuration or transmission using a second data radio bearer configuration based on a trigger, or

[0035] Wherein the control circuitry is configured to open or close the data transfer session based on a trigger.

[0036] An apparatus wherein a trigger is received as a medium access control (MAC) message.

[0037] An apparatus wherein a trigger indicates a mapping between data radio bearers and data transmission sessions for a cell, the mapping to be used in a received first configuration or a second configuration of the cell.

[0038] An apparatus wherein the first data radio bearer configuration or the second data radio bearer configuration comprises at least one mapping between available data transmission sessions to provide data for transmission and available data radio bearers to provide a transmission channel for the data.

[0039] An apparatus wherein at least one mapping maps a data transmission session to a subset of a set of a plurality of preconfigured data radio bearers, wherein the subset is indicated by a trigger.

[0040] An apparatus wherein the data transfer session is a pre-existing data transfer session.

[0041] A device, wherein

[0042] The first data radio bearer configuration and the second data radio bearer configuration configure data radio bearers for the first data transfer session and the second data transfer session,

[0043] in

[0044] If the trigger indicates use of the first data radio bearer configuration, performing data transmission with the user equipment via the cell using the first data radio bearer configuration comprises: performing a second data transmission session with the first data radio bearer configuration, and

[0045] Performing data transmission with the user equipment via the cell using the second data radio bearer configuration if the trigger indicates use of the second data radio bearer configuration includes performing a second data transmission session with the second data radio bearer configuration.

[0046] A device, wherein

[0047] There are states in which the data transfer session is mapped to a subset of the set of multiple preconfigured data radio bearers, and states in which the data transfer session is not mapped to any preconfigured data radio bearer, wherein the states are indicated by the trigger.

[0048] An apparatus wherein a first data radio bearer configuration and a second data radio bearer configuration are configured as data radio bearers for at least a first data transmission session, and optionally a second data transmission session,

[0049] in

[0050] If the trigger indicates use of the first data radio bearer configuration, performing a second data transmission between the user equipment and the cell using the first data radio bearer configuration comprises: performing a second data transmission session with the first data radio bearer configuration,

[0051] Performing a second data transmission between the user equipment and the cell using the second data radio bearer configuration if the trigger indicates use of the second data radio bearer configuration includes performing a second data transmission session with the second data radio bearer configuration.

[0052] A method in which the performance of data transmission between a cell and a user equipment requires a mapping between available data transmission sessions for providing the transmitted data and available data radio bearers for providing a transport channel for the data.

[0053] A method wherein at a time when data transmission between a user equipment and a cell is triggered using a data radio bearer for the cell as a result of a received trigger, there exists a mapping between the data radio bearer for the cell and a data transmission session for the cell.

[0054] A method wherein data transmission between a user equipment and a cell requires

[0055] - available data transfer sessions to provide data for transmission,

[0056] - available data radio bearers, used to provide a transport channel for data,

[0057] in

[0058] At the time of triggering, a data radio bearer for the cell is available for the cell,

[0059] and

[0060] At the time of downlink signalling, the data radio bearer for the cell is not available for the cell,

[0061] and / or

[0062] in

[0063] At the time of triggering, a data transfer session is available for the cell, and

[0064] At the time of signaling, the data transmission session is not available for the cell.

[0065] A method in which

[0066] At the time of the trigger, a data transfer session is available for the cell and a data radio bearer is available for the cell; and

[0067] At the time of downlink signaling,

[0068] A data transmission session is available for the cell, but a data radio bearer is not available for the cell, or

[0069] A data transmission session is not available for the cell, whereas a data radio bearer is available for the cell.

[0070] A device (a network node, such as a gNB and / or a network node supporting central unit and / or distributed unit functions and / or layer 2 protocol and / or layer 3 protocol processing of a radio access network such as LTE, 5G, NR, etc.) is configured to receive and use a configuration of a first data radio bearer configuration for a cell and a configuration of a second data radio bearer configuration for the cell to enable downlink signaling of the first data radio bearer configuration for the cell and the second data radio bearer configuration for the cell.

[0071] An apparatus is configured to receive and use at least one decision criterion for causing a transmission of a trigger to a user equipment and / or setting a mapping parameter in the trigger.

[0072] An apparatus wherein the decision criteria specifies at least one of the following:

[0073] a. Availability of data radio bearers at the current cell,

[0074] b. Availability of data radio bearers at future cells,

[0075] c. New data transfer session.

[0076] An apparatus is configured to receive and use a report comprising information for enabling transmission of a trigger to a user equipment and / or setting a decision criterion for a mapping parameter in the trigger.

[0077] An apparatus is configured to receive and use a report comprising information indicating availability of data radio bearers at a cell for enabling a trigger for transmission to a user equipment and / or setting decision criteria for mapping parameters in the trigger.

[0078] An apparatus wherein the reporting is periodic reporting or event-based reporting.

[0079] An apparatus wherein a report indicates a lack of resources or a presence of resources for one or more data radio bearer configurations.

[0080] An apparatus wherein the trigger is a medium access control (MAC) layer message.

[0081] An apparatus, wherein the apparatus determines cell switching according to a Low Layer Triggered Mobility procedure (LTM).

[0082] A device is configured as a distributed unit of a centralized unit distributed unit network architecture.

[0083] An apparatus, wherein the apparatus is configured to receive and process an indication of a newly established data radio bearer from a centralized unit.

[0084] An apparatus wherein a centralized unit determines a cell handover according to a Low Layer Triggered Mobility procedure (LTM) and notifies the apparatus.

[0085] An apparatus is configured to receive and process an indication from a centralized unit that a first data radio bearer configuration and a second data radio bearer configuration have been sent to a user equipment.

[0086] An apparatus is configured to receive and process decision criteria for causing a triggering of a transmission to a user equipment.

[0087] An apparatus wherein the decision criteria specifies at least one of the following:

[0088] a. Availability of data radio bearers at the current cell,

[0089] b. Availability of data radio bearers at the cell,

[0090] c. New data transfer session.

[0091] An apparatus is configured for receiving and using a report comprising information indicating the availability of data radio bearers at a cell for comparison with a decision criterion for causing a transmission to a triggered user equipment.

[0092] An apparatus wherein the reporting is periodic reporting, or event-based reporting, and / or

[0093] The report indicates a lack of resources or an existence of resources for one or more data radio bearer configurations.

[0094] In some, but not necessarily all, examples, a user equipment is configured to: receive first downlink signaling (from a first source) providing a first data radio bearer configuration, and separately receive second downlink signaling (from the first source) providing a second data radio bearer configuration. The downlink signaling includes the first downlink signaling and the second downlink signaling. The downlink signaling may be sent using a downlink control channel, such as a PDCCH. The downlink signaling content may be sent using, for example, a downlink control message (e.g., layer 3 RRC reconfiguration message(s) and / or layer 2 MAAC CE message(s).

[0095] In some, but not necessarily all, examples, the user equipment is configured to receive first downlink signaling (from a first source) providing a first data radio bearer configuration, and separately receive second downlink signaling (from a second source different from the first source) providing a second data radio bearer configuration. The downlink signaling includes the first downlink signaling and the second downlink signaling.

[0096] In some, but not necessarily all, examples, the user equipment is configured to receive downlink signaling via the first cell and / or the user equipment is configured to receive a trigger via the first cell.

[0097] In some but not necessarily all examples, the apparatus is configured to send downlink signaling via the first cell and / or the apparatus is configured to send a trigger via the first cell.

[0098] In some examples, the first cell and the second cell are different cells. In other examples, the first cell and the second cell are the same cell.

[0099] In some examples, the first cell is a source cell for the UE, and the second cell is a target cell for the UE, such as a handover target cell for the UE.

[0100] Although the above examples and optional features of the present disclosure are described separately, it should be understood that they are provided in all possible combinations and arrangements and are included in the present disclosure. It should be understood that various examples of the present disclosure may include any or all features described with respect to other examples of the present disclosure, and vice versa. In addition, it should be understood that any one or more or all features (in any combination) may be implemented / included in / executable by devices, methods and / or computer program instructions as needed and where appropriate. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Some examples will now be described with reference to the accompanying drawings, in which:

[0102] Figure 1 An example of triggering the use of pre-configured data radio bearer configuration is shown;

[0103] Figure 2 and Figure 3 Examples of different uses of triggering pre-configured data radio bearer configuration are shown;

[0104] Figure 4 and Figure 5 Examples of different uses of triggering pre-configured data radio bearer configuration are shown;

[0105] Figure 6 An example of low-layer triggered mobility and handover is shown;

[0106] Figure 7A and Figure 7B shows the Centralized Unit (CU) Distributed Unit (DU) architecture;

[0107] Figure 8 An example of triggering data transmission in different cells is illustrated;

[0108] Figure 9 An example of event-based triggering is illustrated;

[0109] Figure 10A illustrates an operational map of the first embodiment created by triggering the use of pre-configured data radio bearer configuration;

[0110] Figure 10B illustrates an operational map of the second embodiment created by triggering the use of pre-configured data radio bearer configuration;

[0111] Figure 11A 、 Figure 11B 、 Figure 11C An example of the first embodiment is illustrated.

[0112] Figure 12A 、 Figure 12B 、 Figure 12CAn example of the second embodiment is illustrated.

[0113] Figure 13A An example of a controller is illustrated;

[0114] Figure 13B An example of a computer program is illustrated;

[0115] Figure 14 A cellular telecommunications network is illustrated;

[0116] Figure 15 A method is illustrated;

[0117] FIG16 illustrates an example of the third embodiment.

[0118] The drawings are not necessarily to scale. For clarity and conciseness, certain features and views of the drawings may be shown schematically or exaggerated in scale. For example, the dimensions of some elements in the drawings may be exaggerated relative to other elements to facilitate explanation. Similar reference numerals are used in the drawings to indicate similar features. For clarity, not all reference numerals are necessarily shown in all drawings.

[0119] In the following description, reference numerals without subscript indices (e.g., 10) may be used to refer to a class (or collection), reference numerals with numeric subscript indices (e.g., 10_1) may be used to refer to a specific instance of a class (member of a collection), and reference numerals with variable subscript indices (e.g., 10_i) may be used to refer to a non-specific instance of a class. DETAILED DESCRIPTION

[0120] The following description describes various examples. For the same or similar features, the same reference numerals are used in the drawings.

[0121] The figures and description relate to an example of a user equipment (UE) 110 that includes:

[0122] means for receiving 2 signalling 11 providing a first data radio bearer configuration 10_1 (DRB_1) for a cell 120_2 and a second data radio bearer configuration 10_2 for the cell 120_2;

[0123] means for storing 4 a first data radio bearer configuration 10_1 for performing a data transmission 15 via the cell 120_2 using a first data radio bearer (DRB_1) and for storing 4 a second data radio bearer configuration 10_2 for performing a data transmission 15 via the cell 120_2 using a second data radio bearer (DRB_2);

[0124] Component for receiving 6 120_1 and triggering 13; and

[0125] Means for, in response to a received trigger 13:

[0126] If the trigger 13 indicates the use of the first data radio bearer configuration 10_1, performing a data transmission 15 between the user equipment (UE) 110 and the cell 120_2 using the first data radio bearer configuration 10_1, and

[0127] If the trigger 13 indicates the use of the second data radio bearer configuration 10_2, data transmission 15 is performed between the user equipment (UE) 110 and the cell 120_2 using the second data radio bearer configuration 10_2.

[0128] The figures and description relate to an example of an apparatus 120 (132) for a cellular telecommunications network (such as a radio access network), the apparatus comprising:

[0129] means for causing transmission of signaling 11 to a user equipment (UE) 110, the signaling providing a first data radio bearer configuration 10_1 (DRB_1) for a cell 120_2 and a second data radio bearer configuration 10_2 (DRB_2) for the cell 120_2; means for causing transmission of a trigger 13 to the user equipment (UE) 110, the trigger being configured to indicate use of the first data radio bearer configuration 10_1 to enable data transmission 15 between the user equipment (UE) 110 and the cell 120_2 using the first data radio bearer (DRB_1),

[0130] is configured to indicate use of a second data radio bearer configuration 10_2 to enable data transmission 15 between a user equipment (UE) 110 and a cell 120_2 using a second data radio bearer (DRB_2).

[0131] In some, but not necessarily all, examples, the user equipment 110 is configured to receive first signaling (from a first source) providing a first data radio bearer configuration 10_1 and separately receive second signaling (from the first source) providing a second data radio bearer configuration 10_2. The signaling 11 includes the first signaling and the second signaling.

[0132] In some, but not necessarily all, examples, the user equipment 110 is configured to receive first signaling (from a first source) providing a first data radio bearer configuration 10_1, and separately receive second signaling (from a second source different from the first source) providing a second data radio bearer configuration 10_2. The signaling 11 includes the first signaling and the second signaling.

[0133] In at least some examples, the apparatus 120 is configured to send signaling 11 via the first cell, and / or the apparatus 120 is configured to send trigger 13 via the first cell (the first cell mentioned above). The signaling 11 may be, for example, downlink signaling.

[0134] In at least some examples, the user equipment 110 is configured to receive signaling 11 via the first cell, and / or the user equipment is configured to receive trigger 13 via the first cell (the first cell mentioned above). The signaling 11 may be, for example, downlink signaling.

[0135] In at least some examples, the apparatus 120 is configured to send signaling 11 via the first cell, and / or the apparatus 120 is configured to send trigger 13 via the first cell (the first cell mentioned above). The signaling 11 may be, for example, downlink signaling.

[0136] In some examples, the first cell and the second cell are different cells. In other examples, the first cell and the second cell are the same cell.

[0137] In some examples, the first cell is a source cell for the UE, and the second cell is a target cell for the UE, such as a handover target cell for the UE.

[0138] The drawings and description relate to some examples.

[0139] Figure 1 The diagram shows part of a cellular telecommunication network comprising a cell served by an apparatus 120. The apparatus 120 is a radio access device that communicates with a user equipment 110 using radio waves. Figure 1 In the example, the first cell (Cell_1) is served by the first device 120_1, and the second cell (Cell_2) is served by the second device 120_2.

[0140] A user equipment (UE) is initially located in a first cell (cell_1) and is initially served by a first device 120_1.

[0141] In the following description, a first cell may be referenced using a textual reference 'Cell_1' or a numerical reference '120_1', which is a reference to a first device 120_1 serving the first cell. In the following description, a second cell may be referenced using a textual reference 'Cell_2' or a numerical reference '120_2', which is a reference to a second device 120_2 serving the second cell.

[0142] As will be described later, user equipment 110 includes circuitry or other components for receiving 2 downlink signaling 11, circuitry or other components for storing 4 information including data radio bearer configurations 10, circuitry or other components for receiving 6 a trigger 13, and circuitry or other components for conditionally performing data transmission 15 between user equipment (UE) 110 and second cell 120_2 using one or more data radio bearer configurations 10 based on the received trigger 13. The described circuitry may be configured for the described purposes.

[0143] The user equipment 110 comprises means for receiving 2 downlink signalling 11 via the first cell 120_1 , the downlink signalling providing a first data radio bearer configuration 10_1 for the second cell 120_2 and a second data radio bearer configuration 10_2 for the second cell 120_2 .

[0144] The user equipment 110 comprises means for storing 4 a first data radio bearer configuration 10_1 for performing a data transmission 15 via the second cell 120_2 using a first data radio bearer (DRB_1), and for storing 4 a second data radio bearer configuration 10_2 for performing a data transmission 15 via the second cell 120_2 using a second data radio bearer (DRB_2).

[0145] The user equipment 110 comprises means for receiving 6 a trigger 13 via the first cell 120_1 .

[0146] The user equipment 110 comprises means for, in response to a received trigger 13:

[0147] i) if the trigger 13 indicates use of the first data radio bearer configuration 10_1, performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1, and

[0148] ii) If the trigger 13 indicates the use of the second data radio bearer configuration 10_2, data transmission 15 is performed between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2.

[0149] Downlink signaling 11 is sent by the first device 120_1 of the first cell (Cell_1) and received 2 by the user equipment 110. A trigger 13 is sent by the first device 120_1 of the first cell (Cell_1) and received 2 by the user equipment 110.

[0150] The data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 can be an uplink transmission, i.e., a transmission from the user equipment 110 to the first device 120_1 of the first cell (Cell_1), and / or can be a downlink transmission, i.e., a transmission received at the user equipment 110 from the first device 120_1 of the first cell (Cell_1).

[0151] A data radio bearer configuration 10 is a set of information that can be used to establish and use one or more data radio bearers (DRBs). A data radio bearer (DRB) is a transport channel for data. A first data radio bearer configuration 10_1 may relate to a first set of data radio bearers (DRB_1) that may include one or more data radio bearers. A second data radio bearer configuration 10_2 may relate to a second set of data radio bearers (DRB_2) that may include one or more data radio bearers.

[0152] In at least some examples, user equipment 110 includes means for, in response to receiving a trigger 13, determining at least whether the received trigger 13 indicates use of a first data radio bearer configuration 10_1, or whether the received trigger 13 indicates use of a second data radio bearer configuration 10_2 for a QoS flow. Indicating that the radio bearer is not associated with a QoS flow, the radio bearer is not used at all by the user equipment (UE). In this example, as a result of determining that the received trigger 13 indicates use of the first data radio bearer configuration 10_1, the user equipment further includes means for performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1. As a result of determining that the received trigger 13 indicates use of the second data radio bearer configuration 10_2, the user equipment further includes means for performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2.

[0153] The downlink signalling 11 and the trigger 13 are different messages sent independently. The reason for sending the downlink signalling 11 to establish an appropriate data radio bearer (DRB) is separate and distinct from the reason for sending the trigger 13 to perform the use of one or more previously established data radio bearers.

[0154] In some, but not necessarily all, examples, trigger 13 is sent as a result of an event, and the trigger includes at least an indication of the event.

[0155] The downlink signaling 11 enables future performance of the data transmission 15 (in response to the trigger 13) without the need for additional downlink signaling to provide configuration information for the data radio bearer.

[0156] The downlink signalling 11 is received 2 via the first cell and the trigger 13 is received via the first cell. However, the data transmission performed in response to the trigger 13 (or independently of the trigger 13) is received via the second cell.

[0157] In at least some examples, trigger 13 can be used to trigger configuration of a pre-configuration, which can occur before the trigger is sent to the UE.

[0158] In some, but not necessarily all, examples, trigger 13 is not a data radio bearer configuration message and does not enable transmission of a data radio bearer configuration message. Thus, in some, but not necessarily all, examples, messaging for configuring a data radio bearer at user equipment 110 may be avoided in the period between trigger 13 and initiation of data transmission 15. Trigger 13 triggers a pre-stored data radio bearer configuration 10.

[0159] In at least some examples, user equipment 110 does not send a message acknowledging receipt of trigger 13, although there may be a report of the results of trigger 13.

[0160] Therefore, the separation of downlink signaling 11 and triggering 13 may increase the speed of operation and reduce radio signaling.The speed of operation may be increased because the trigger is a small message that may only indicate the use of a pre-configured UE's data radio bearer.

[0161] The trigger 13 enables a future execution of a data radio bearer (DRB) for data transmission 15 in the second cell 120_2 , regardless of whether the future represents a time separation from the downlink signaling 11 .

[0162] In some examples, the trigger 13 explicitly indicates the use of the first data radio bearer configuration 10_1, for example using a predetermined flag. In some examples, the trigger 13 implicitly indicates the use of the first data radio bearer configuration 10_1, for example by providing information that is interpreted by the user equipment 110 as an indication to use the first data radio bearer configuration 10_1 due to the shared context.

[0163] In some, but not necessarily all, examples, the trigger 13 indicates the first data radio bearer configuration 10_1. In some examples, the trigger 13 explicitly indicates the first data radio bearer configuration 10_1, for example, using a predetermined flag. In some examples, the trigger 13 implicitly indicates the first data radio bearer configuration 10_1, for example, by providing information that is interpreted by the user equipment 110 as an indication of the first data radio bearer configuration 10_1 due to the shared context.

[0164] In some, but not necessarily all, examples, the trigger indicates which part of the optional RRC configuration the user equipment should use.

[0165] In at least some examples, the execution 8 of data transmission 15 between user equipment 110 and second cell 120_2 requires an operational mapping 14 between available data transmission sessions (DTS) 12 and available data radio bearers (DRBs). Available data transmission sessions (DTS) 12 route data for transmission. Available data radio bearers (DRBs) provide a transmission channel for the data.

[0166] Figure 2 The diagram illustrates an assumed mapping between a data transmission session (DTS) 12 and a data radio bearer (DRB). When at least some of the mapping is available, data transmission 15 becomes possible. An assumed mapping exists between a first data transmission session (DTS_1) 12_1 and a first data radio bearer (DRB_1) defined by a first data radio bearer configuration 10_1 or a second data radio bearer (DRB_2) defined by a second data radio bearer configuration 10_2. An assumed mapping exists between a second data transmission session (DTS_2) 12_2 and a third data radio bearer (DRB_3) defined by a third data radio bearer configuration 10_3.

[0167] As will be explained later, mapping is assumed but not operational at a specific cell because, before trigger 13 is received, one or both of the data radio bearer and the data transfer session may have different data radio bearers at the specific cell. A different radio bearer may also be a non-data radio bearer. The UE may use the data transfer session at the target and the mapping to the data radio bearer. The mapping is indicated by the trigger. However, if the trigger does not indicate a mapping, the multiple configurations of the mapping may include a default mapping, which is used in the absence of an explicit mapping of the data transfer session to the data radio bearer.

[0168] Data may be routed for transmission via an available Data Transport Session (DTS) 12. Available Data Radio Bearers (DRBs) 10 provide an operating transport channel for the data.

[0169] Figure 3 The diagram shows how trigger 13 makes Figure 2 The assumed mapping becomes the operation mapping 14.

[0170] In one scenario (illustrated on the left), a trigger 13 indicates the use of a first data radio bearer configuration 10_1 and causes the creation of an operational mapping 14_1 between a first data transmission session (DTS_1) 12_1 and a first data radio bearer (DRB_1) defined by the first data radio bearer configuration 10_1. Optionally, an operational mapping 14_2 also exists between a second data transmission session (DTS_2) 12_2 and a third data radio bearer (DRB_3) defined by a third data radio bearer configuration 10_3.

[0171] The operational mapping 14_1 is between the first data transmission session (DTS_1) 12_1 and the first data radio bearer (DRB_1), but not between the first data transmission session (DTS_1) 12_1 and the second data radio bearer (DRB_2). In this example, but not necessarily all examples, the operational mapping 14_1 is between the first data transmission session (DTS_1) 12_1 and only the first data radio bearer (DRB_1).

[0172] The operation mapping 14_1 is used to perform data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using a first data radio bearer configuration 10_1.

[0173] In another scenario (illustrated on the right), trigger 13 indicates the use of a second data radio bearer configuration 10_2 and causes the creation of an operational mapping 14_3 between a first data transmission session (DTS_1) 12_1 and a second data radio bearer (DRB_2) defined by the second data radio bearer configuration 10_2. Optionally, an operational mapping 14_4 also exists between the second data transmission session (DTS_2) 12_2 and a third data radio bearer (DRB_3) defined by the third data radio bearer configuration 10_3.

[0174] The operation mapping 14_3 is between the first data transmission session (DTS_1) 12_1 and the second data radio bearer (DRB_2), but not between the first data transmission session (DTS_1) 12_1 and the first data radio bearer (DRB_1). In this example, but not necessarily all examples, the operation mapping 14_3 is between the first data transmission session (DTS_1) 12_1 and only the second data radio bearer (DRB_2).

[0175] The operation mapping 14_3 is used to perform data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using a second data radio bearer configuration 10_2.

[0176] In some, but not necessarily all, examples, the first data radio bearer and the second data radio bearer have different characteristics, such as bandwidth, latency, reliability, and / or quality of service.

[0177] In some examples, the first data radio bearer has lower bandwidth, greater latency, worse reliability, and / or lower quality of service than the second data radio bearer.

[0178] In some, but not necessarily all, examples, the first data radio bearer is a default data radio bearer.

[0179] Therefore, the user equipment 110 includes:

[0180] means for receiving 2 downlink signalling 11 via the first cell 120_1 , the downlink signalling providing a first data radio bearer configuration 10_1 for the second cell 120_2 and a second data radio bearer configuration 10_2 for the second cell 120_2 ;

[0181] means for storing 4 a first data radio bearer configuration 10_1 for performing a data transmission 15 via the second cell 120_2 using a first data radio bearer (DRB_1), and for storing 4 a second data radio bearer configuration 10_2 for performing a data transmission 15 via the second cell 120_2 using a second data radio bearer (DRB_2);

[0182] means for receiving 6 triggering 13 via the first cell 120_1;

[0183] Means for, in response to a received trigger 13:

[0184] i) if the trigger 13 indicates use of the first data radio bearer configuration (DRB_1) 10_1, performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer (DRB_1) defined by the first data radio bearer configuration 10_1, and

[0185] ii) If the trigger 13 indicates usage of the second data radio bearer configuration (DRB_2) 10_2, data transmission 15 is performed between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer (DRB_2) defined by the second data radio bearer configuration 10_2.

[0186] Figure 4 Illustrated is a hypothetical mapping between Data Transfer Sessions (DTS) 12 and Data Radio Bearers (DRBs).When at least some mapping is available, the performance of a data transfer 15 becomes possible.

[0187] There is an assumed mapping between a first data transmission session (DTS_1) 12_1 and a first data radio bearer (DRB_1) defined by a first data radio bearer configuration 10_1, or there is no mapping. There is an assumed mapping between a second data transmission session (DTS_2) 12_2 and a second data radio bearer (DRB_2) defined by a second data radio bearer configuration 10_2.

[0188] As will be explained later, the mapping is assumed but not operational because one or both of the data radio bearer or the data transmission session are not available before the trigger 13 is received.

[0189] Data may be routed for transmission via an available Data Transport Session (DTS) 12. Available Data Radio Bearers (DRBs) 10 provide an operating transport channel for the data.

[0190] Figure 5 The diagram shows how trigger 13 makes Figure 4 The assumed mapping becomes the operational mapping 14.

[0191] In one scenario (illustrated on the left), a trigger 13 indicates the use of a first data radio bearer configuration 10_1 and causes the creation of an operational mapping 14_1 between a first data transmission session (DTS_1) 12_1 and a first data radio bearer (DRB_1) defined by the first data radio bearer configuration 10_1. Optionally, an operational mapping 14_2 also exists between a second data transmission session (DTS_2) 12_2 and a second data radio bearer (DRB_2) defined by the second data radio bearer configuration 10_2.

[0192] The operational mapping 14_1 is between the first data transmission session (DTS_1) 12_1 and the first data radio bearer (DRB_1), but not between the first data transmission session (DTS_1) 12_1 and the second data radio bearer (DRB_2). In this example, but not necessarily all examples, the operational mapping 14_1 is between the first data transmission session (DTS_1) 12_1 and only the first data radio bearer (DRB_1).

[0193] The operation mapping 14_1 is used to perform data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using a first data radio bearer configuration 10_1.

[0194] In another scenario (illustrated on the right), a trigger 13 indicates the use of a second data radio bearer configuration 10_2 and causes the creation of an operational mapping 14_3 between a second data transport session (DTS_2) 12_2 and a second data radio bearer (DRB_2) defined by the second data radio bearer configuration 10_2.

[0195] The operation mapping 14_3 is between the second data transmission session (DTS_2) 12_2 and the second data radio bearer (DRB_2), but not between the second data transmission session (DTS_2) 12_2 and the first data radio bearer (DRB_1). In this example, but not necessarily all examples, the operation mapping 14_3 is between the second data transmission session (DTS_2) 12_2 and only the second data radio bearer (DRB_2).

[0196] The operation mapping 14_3 is used to perform data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using a second data radio bearer configuration 10_2.

[0197] In some but not necessarily all examples, the first data radio bearer DRB_1 and the second data radio bearer DRB_2 have different characteristics, such as bandwidth, latency, reliability, and / or quality of service.

[0198] Therefore, the user equipment 110 includes:

[0199] means for receiving 2 downlink signalling 11 via the first cell 120_1 , the downlink signalling providing a first data radio bearer configuration 10_1 for the second cell 120_2 and a second data radio bearer configuration 10_2 for the second cell 120_2 ;

[0200] means for storing 4 a first data radio bearer configuration 10_1 for performing a data transmission 15 via the second cell 120_2 using a first data radio bearer (DRB_1), and for storing 4 a second data radio bearer configuration 10_2 for performing a data transmission 15 via the second cell 120_2 using a second data radio bearer (DRB_2);

[0201] means for receiving 6 triggering 13 via the first cell 120_1;

[0202] Means for, in response to a received trigger 13:

[0203] i) if the trigger 13 indicates use of the first data radio bearer configuration (DRB_1) 10_1, performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer (DRB_1) defined by the first data radio bearer configuration 10_1, and

[0204] ii) If the trigger 13 indicates usage of the second data radio bearer configuration (DRB_2) 10_2, data transmission 15 is performed between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer (DRB_2) defined by the second data radio bearer configuration 10_2.

[0205] Therefore, in Figure 3 In the embodiment, if the trigger 13 indicates the use of the first data radio bearer configuration 10_1, the first data radio bearer configuration 10_1 is used for data transmission 15, or if the trigger 13 indicates the use of the second data radio bearer configuration 10_2, the second data radio bearer configuration 10_2 is used for data transmission 15.

[0206] Therefore, in Figure 5 In the embodiment, if the trigger 13 indicates the use of the second data radio bearer configuration 10_2, the second data radio bearer configuration 10_2 is used instead of the first data radio bearer configuration 10_1 for data transmission 15. Alternatively, if the trigger 13 indicates the use of the first data radio bearer configuration 10_1, the first data radio bearer configuration 10_1 is used instead of the second data radio bearer configuration 10_2 for data transmission 15.

[0207] Figure 6 An example of switching is illustrated.

[0208] In this example, before a handover (also referred to as hand-off), data communication exists between user equipment 110 and radio access device 120_1 of a first cell (Cell_1). After handover 26, data communication 20 exists between user equipment 110 and radio access device 120_2 of a second cell (Cell_2). The handover decision is based on a measurement report 22 provided by the user equipment.

[0209] Optionally, a low layer triggered mobility (LTM) may be established 24 prior to the handover 26 and the handover decision may then be made at a low layer (eg at the radio access device).

[0210] The decision to establish an LTM may be based on the measurement report 22 provided by the user equipment 110 .

[0211] Low Layer Triggered Mobility (LTM) results in a decision being made at a lower layer to perform a handover 26. The decision is made at Layer 2 or Layer 1 (eg, Medium Access Control) rather than Layer 3 (Radio Resource Control, RRC).

[0212] Thus, the handover decision may be made at the radio access device (eg, at the control plane of the radio access device). In some examples, this may occur at a distributed unit (DU).

[0213] For example, low layer triggered mobility (LTM) may be controlled by a low layer entity at the radio access device 120_1. In some, but not necessarily all, examples, low layer triggered mobility (LTM) may be controlled by a medium access control (MAC) entity at the radio access device 120_1. Trigger 13 originates from the MAC entity in the radio access control device 120 and may be, for example, a MAC message.

[0214] There are various different architectures that may be used for the radio access device 120 .

[0215] The radio access device 120 is a cellular base station. In some, but not necessarily all, examples, the base station may have a decentralized architecture. In this case, the base station includes a centralized unit (CU) and one or more distributed units (DUs).

[0216] The centralized unit (CU) and the distributed unit(s) (DU) divide the base station into different logical entities, and optionally into different physical entities.

[0217] A DU can support one or more cells. Each cell has one or more associated transmission reception points.

[0218] In a common architecture, DUs are physically separated from each other and located close to the transmission reception point(s) associated with the DUs.

[0219] In a common architecture, there is one CU per base station, and the CU controls one or more DUs.

[0220] CU provides a high-level interface to the core network (the upper layer of the protocol stack). DU provides a low-level interface to the UE (the lower layer of the protocol stack).

[0221] The 3GPP protocol stack includes:

[0222]

[0223] The MAC entity can be within the DU. In case of LTM operation, the handover decision can be made at the DU.

[0224] Figure 7AThe diagram illustrates an example in which a first cell (Cell_1) and a second cell (Cell_2) are controlled by a common CU 134. A first DU 132_1 controlled by the CU 134 provides a first radio access device 110_1. A second CU 132_2 controlled by the DU 134 provides a second radio access device 110_2.

[0225] Figure 7B The diagram shows an example in which a first cell (Cell_1) and a second cell (Cell_2) are controlled by different DUs 134. A first DU 132_1 controlled by a first CU 134_1 provides a first radio access device 110_1. A second DU 132_2 controlled by a second CU 134_2 provides a second radio access device 110_2.

[0226] The CUs 134 may communicate with each other directly or via the core network 129 .

[0227] The DU 132_1 may send downlink signaling 11 providing a first data radio bearer configuration 10_1 for the second cell 120_2 and a second data radio bearer configuration 10_2 for the second cell 120_2 , and may send a trigger 13 via the first cell 120_1 .

[0228] Figure 8 An example is illustrated in which the user equipment 110 includes the following items:

[0229] means for receiving, via the first cell 120_1, downlink signalling 11 providing at least a first configuration of a first data radio bearer (DRB_1) (DRB) for the first (serving) cell and a second configuration of a second data radio bearer (DRB_2) (DRB) for the second (non-serving) cell;

[0230] means for storing a first configuration 10_1 of a first data radio bearer (DRB_1) for the first cell 120_1 for performing a data transmission 15_2 via the first cell 120_1 using the first data radio bearer (DRB_2);

[0231] A second configuration 10_2 for storing a second data radio bearer (DRB_2) for the second cell 120_2 for future use of the first data radio bearer (DRB_2)

[0232] means for performing data transmission 15_2 via the first cell 120_1;

[0233] means for performing a data transmission 15_1 between a user equipment (UE) 110 and a first cell 120_1 using a first data radio bearer (DRB_1) in response to a trigger 13_1;

[0234] Means for performing data transmission 15_2 between the user equipment (UE) 110 and the second cell 120_2 using a second data radio bearer (DRB_2) in the future in response to the trigger 13_2.

[0235] In some examples, the first configuration 10_1 is performed on the first cell 120_1 for the first data transmission session 12_1, while the second configuration 10_2 is not performed on the first cell 120_1 for the data transmission session 12. After handover from the first cell 120_1 to the second cell 120_2, the second DRB configuration 10_2 is performed on the second cell 120_2 for the first data transmission session or the second data transmission session 12_2.

[0236] In some examples, the second data transfer session 12_2 is a continuation of the first data transfer session 12_1 .

[0237] In some other examples, the second data transmission session 12_2 is a different data transmission session 12 than the first data transmission session.

[0238] Figure 9 An example of a user equipment (UE) 110 is illustrated, the UE comprising:

[0239] means for receiving, via the first cell 120_1 , downlink signalling 11 , the downlink signalling 11 providing at least a configuration 10 of a data radio bearer (DRB) for the second cell 120_2 ;

[0240] means for storing at least a configuration 10 of a data radio bearer (DRB) for the second cell 120_2 for performing a data transmission 15 via the second cell 120_2 using the data radio bearer (DRB) in the future;

[0241] A component for storing an operation mapping 14 between a data radio bearer (DRB) and a data transmission session 12 in response to a trigger 13 for performing data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using the data radio bearer (DRB), and a component for performing data transmission 15 of the data transmission session 12 between the user equipment (UE) 110 and the second cell 120_2 using the data radio bearer (DRB) using the operation mapping 14.

[0242] In some, but not necessarily all, examples, the trigger 13 is sent as a result of the event 30, and the trigger 13 includes at least an indication of the event. For example, the event may relate to a data transmission session 12, a data radio bearer (DRB), a data radio bearer configuration 10, or a mapping between a data transmission session 12 and a data radio bearer (DRB) defined by the data radio bearer configuration 10.

[0243] In some but not necessarily all examples, the trigger 13 indicates a mapping 14 to be used to map the received first DRB configuration 10_1 for the second cell (Cell_2) or the received second DRB configuration 10_2 for the second cell (Cell_2) to a data transmission session 12.

[0244] The user equipment 110 may include: a component for storing an operation mapping 14 between a data radio bearer (DRB) and a data transmission session 12 in response to a trigger 13 for performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the data radio bearer (DRB), and a component for using the operation mapping 14 to perform data transmission 15 of the data transmission session 12 between the user equipment (UE) 110 and the second cell 120_2 using the data radio bearer (DRB).

[0245] Trigger 13 may complete an existing mapping and make it operational, or make an existing complete mapping operational.

[0246] The mapping may be stored as part of a DRB configuration. For example, a first DRB configuration 10_1 may include data defining a mapping or operational mapping 14 between available data transmission sessions 12 for providing data for transmission and available first data radio bearers (DRBs) for providing a transmission channel for the data.

[0247] For example, the second DRB configuration 10_2 may include data defining a mapping or operational mapping 14 between available data transmission sessions 12 for providing data for transmission and available second data radio bearers (DRBs) for providing a transmission channel for the data.

[0248] In some examples, no operational mapping 14 is possible between available data transmission sessions 12 to provide data for transmission and available data radio bearers (DRBs) to provide a transmission channel for the data.

[0249] like Figure 10A and Figure 10BAs shown in , execution of data transmission 15 between a user equipment (UE) 110 and a cell requires: available data transmission sessions 12 for providing data for transmission, available data radio bearers (DRBs) for providing a transmission channel for the data, and (at least in some examples) an operational mapping 14 between the available data transmission sessions 12 and the available data radio bearers (DRBs).

[0250] At time t_1 of the downlink signaling 11 , there is no operational mapping 14 of the second cell 120_2 between a data radio bearer (DRB) for the second cell 120_2 and the data transmission session 12 .

[0251] At time t2 of reception of a trigger 13 that triggers the execution of a data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using a data radio bearer (DRB) for the second cell 120_2 as a result of the received trigger 13, a mapping 14 of the second cell 120_2 exists between the data radio bearer (DRB) for the second cell 120_2 and the data transmission session 12.

[0252] refer to Figure 10A , at time t_1 of the downlink signaling 11, a data radio bearer (DRB) for the second cell 120_2 is not available for the second cell 120_2, and at time t2 of the triggering, a data radio bearer (DRB) for the second cell 120_2 is available for the second cell 120_2.

[0253] Additionally or alternatively, reference Figure 11B , at time t_1 of the downlink signaling 11 , the data transmission session 12 is not available for the second cell 120_2 , and at time t_2 of the triggering, the data transmission session 12 is available for the second cell 120_2 .

[0254] Therefore, at the time of triggering, the data transmission session 12 is available for the second cell 120_2 and the data radio bearer (DRB) for the second cell 120_2 is available for the second cell 120_2; and

[0255] At time t_1 of the downlink signaling 11, the data transmission session 12 is available for the second cell 120_2, while the data radio bearer (DRB) is not available for the second cell 120_2 ( Figure 10A )

[0256] or

[0257] At time t_1 of the downlink signaling 11, the data transmission session 12 is not available for the second cell 120_2, but a data radio bearer (DRB) is available for the second cell 120_2 ( Figure 10B ).

[0258] First embodiment

[0259] Figure 11A 、 Figure 11B 、 Figure 11C Different examples of the first embodiment are illustrated.

[0260] refer to Figure 11A , the process optionally includes the establishment of Low Layer Triggered Mobility (LTM) 24 as described above.

[0261] The procedure comprises a 'configuration phase' downlink signalling 11 which provides a first data radio bearer configuration 10_1 for the second cell 120_2 and a second data radio bearer configuration 10_2 for the second cell 120_2.

[0262] The process comprises an 'event phase', where an event causes a trigger 13 to be transmitted to the user equipment 110. In this example, the event is a change in the availability status of a data radio bearer (DRB), for example, a data radio bearer becomes available or becomes unavailable.

[0263] The process comprises a 'triggering phase', wherein a trigger is sent by the apparatus 120_1 of the first cell (Cell_1) to the user equipment 110.

[0264] exist Figure 11A , the procedure includes a handover phase 26 followed by data transmission 15. As previously described, this includes performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1 if the trigger 13 indicates the use of the first data radio bearer configuration 10_1 (the first data radio bearer is available), or performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2 if the trigger 13 indicates the use of the second data radio bearer configuration 10_2 (the first data radio bearer is not available).

[0265] In some, but not necessarily all, examples, the first data radio bearer and the second data radio bearer have different characteristics, such as bandwidth, latency, reliability, and / or quality of service.

[0266] In some examples, the first data radio bearer has lower bandwidth, greater latency, worse reliability, and / or lower quality of service than the second data radio bearer.

[0267] In some, but not necessarily all, examples, the first data radio bearer is a default data radio bearer.

[0268] In at least some examples, trigger 13 enables the user device to create an operational map 14, as previously described.

[0269] The data transfer session 12 is mapped to a subset of a set of a plurality of pre-configured data radio bearers (DRBs) by an operational mapping 14 for data transfer, wherein the subset is selected by a trigger 13 .

[0270] If the trigger 13 indicates usage of the first data radio bearer configuration 10_1 (eg indicates a first data radio bearer), the selected subset is the first data radio bearer.

[0271] If the trigger 13 indicates usage of the second data radio bearer configuration 10_2 (eg indicates that the first data radio bearer is unavailable or does not indicate availability of the first data radio bearer), the selected subset is the second data radio bearer.

[0272] In at least some examples, the data transfer session 12 is a pre-existing data transfer session 12 .

[0273] exist Figure 11B In , the LTM establishment phase and configuration phase are merged.

[0274] The user equipment sends a measurement report 41 to the apparatus 120_1 of the first cell (Cell_1).

[0275] The device 120_1 of the first serving cell (Cell_1) communicates 51 directly or indirectly with the device 120_2 of the second non-serving cell (Cell_2) to establish LTM with 'persistence' of DRB.

[0276] The device 120_2 of the second non-serving cell (Cell_2) communicates 53 directly or indirectly with the device 120_1 of the first serving cell (Cell_1) to identify available DRBs at the second non-serving cell.

[0277] The apparatus 120_1 sends a configuration message 11 to the user equipment 110, which configures the persistence of the DRB configuration at the UE 110. This enables the storage of the first DRB configuration 10_1 and the second DRB configuration 10_2, as previously described.

[0278] At least one of the DRBs (e.g., the first DRB_1 or the second DRB_2) is currently unavailable and cannot be used for data transmission, but is still stored for future use in response to the received trigger 13. This storage for future use is 'persistent' when it is currently unavailable. At least one of the DRBs (e.g., the second DRB_2) is currently available and can be used for data transmission. For example, the second DRB_2 may be a fallback default DRB.

[0279] The user equipment 110 sends an acknowledgement 43 to the configuration message 11 .

[0280] The device 120_2 of the second non-serving cell (Cell_2) directly or indirectly notifies 55 the device 120_1 of the first serving cell (Cell_1) of the availability of the DRB at the second non-serving cell.

[0281] Such notification may occur due to events such as expiration of a periodic timer and / or a change in availability of DRBs at the second non-serving cell (Cell_2).

[0282] The user equipment 110 sends a measurement report 45 to the apparatus 120_1 of the first cell (Cell_1) in order to inform it, among other things, of the current availability of the DRB at the second non-serving cell.

[0283] The apparatus 120_1 of the first cell (Cell_1) determines 60 based on the measurement report 45 that LTM is to be triggered for the second non-serving cell, for example because a handover to the non-serving cell (cell_2) is becoming increasingly probable or possible, or for other reasons.

[0284] The apparatus 120_1 of the first cell (Cell_1), which has determined 60 to trigger LTM for the second non-serving cell, sends a trigger 13 to the user equipment 110. The trigger is used to select a specific DRB for data transmission.

[0285] The device 120_1 of the first serving cell (Cell_1) notifies 57 the device 120_2 of the second non-serving cell (Cell_2) directly or indirectly that a specific DRB has been triggered for the data transmission.

[0286] Alternatively, in some examples, user equipment 110 may inform apparatus 120_2 of a second non-serving cell (Cell_2) that a specific DRB has been triggered for the data transmission.

[0287] Figure 11C Further details of example implementations are illustrated in Reference numerals from previous figures are reused to indicate the same or similar features.

[0288] exist Figure 11C In , the LTM establishment phase and configuration phase are merged.

[0289] The device 120_1 of the first cell is a first DU 132_1 communicating with the CU 134 .

[0290] The device 120_2 of the second cell is a second DU 132_2 in communication with the CU 134 .

[0291] The user equipment sends a measurement report 41 to the first DU 132_1 of the first cell (Cell_1).

[0292] A first DU 132_1 of a first serving cell (Cell_1) indirectly communicates 51 with a second DU 132_2 of a second non-serving cell (Cell_2) via a CU 134 to establish LTM with 'persistence' of the DRBs. In this example, the communication 51 includes sending 71 a measurement report from the first DU 132_1 to the CU 134. The CU 134 determines 64 that LTM is to be triggered. The CU 134 sends a UE content modification request 73 related to LTM for cell 2 to the DU 132_2 of the second cell (cell_2). This notifies the DU 132_2 of the DRBs for cell 2 (e.g., first data radio bearer DRB_1, second data radio bearer DRB_2). The request 73 has a special format that indicates that it is requesting LTM with maintenance (persistence) of the DRB configuration.

[0293] DU 132_2 of the second non-serving cell Cell_2 indirectly communicates 53 with DU 132_1 of the first serving cell (Cell_1) to identify the available DRBs at the second non-serving cell Cell_2. DU 132_2 determines 62 the resources for the DRB specified in the request 73. In this example, the resources for the first DRB_1 are not available, while the resources for the second DRB_2 are available. Even though the resources are not available, the first DRB (DRB_1) will be added / granted (persistence). The second DRB (DRB_2) will be added as an available default DRB for fallback. DU 132_2 sends a UE establishment context setup confirmation 81 regarding the LTM for the second cell (Cell_2) and the specification of the default DRB.

[0294] CU 134 sends an RRC reconfiguration message 11 to DU 132_1 of the first serving cell (Cell_1) for LTM of the second cell (Cell_2). This indicates that the first data radio bearer DRB_1 will be added / permitted but is unavailable, and that the second data radio bearer DRB_2 is a fallback default DRB and is available. RRC reconfiguration message 11 includes a first DRB configuration 10_1 for the first DRB (DRB_1) and a second DRB configuration 10_2 for the second DRB (DRB_2).

[0295] The RRC reconfiguration message 11 is an implicit or explicit instruction to use the default DRB unless an available alternative DRB is subsequently indicated in a trigger 13 .

[0296] DU 132_1 sends a configuration message 11 (RRC reconfiguration message 11) to the user equipment 110. This configures the persistence of the DRB configuration at the UE 110. This enables the storage of the first DRB configuration 10_1 and the second DRB configuration 10_2, as previously described. At least one of the DRBs (e.g., the first DRB_1) is currently unavailable and cannot be used for data transmission, but is still stored for future use in response to the received trigger 13. This storage for future use is 'persistent' when it is currently unavailable. At least one of the DRBs (e.g., the second DRB_2) is currently available and can be used for data transmission. For example, the second DRB_2 can be a fallback default DRB.

[0297] The user equipment 110 sends an acknowledgement 43 to the configuration message 11 .

[0298] DU 132_2 of the second non-serving cell (Cell_2) indirectly notifies 55 DU 132_1 of the first serving cell (Cell_1) of the availability of the DRB of the second non-serving cell. Such notification may occur due to events such as the expiration of a periodic timer and / or a change in the availability of the DRB at the second non-serving cell. In this example, DU 132_2 sends a load status report 83 of the first DRB (DRB_1) and / or the second DRB (DRB_2) to CU 134, e.g., DRB_1 is currently unavailable or DRB_1 is currently available. Then, CU 134 sends a load status report 85 of the first DRB (DRB_1) and / or the second DRB (DRB_2) to DU 132_1, e.g., DRB_1 is currently unavailable or DRB_1 is currently available.

[0299] The user equipment sends a measurement report 45 to the apparatus 120_1 of the first cell (Cell_1) to inform it of the current availability of DRBs at the second non-serving cell. The measurement report is a report of layer 1 (L1) measurements made by the user equipment 110.

[0300] The DU 132_1 of the first cell (Cell_1) determines 60 based on the measurement report 45 that LTM is to be triggered for the second non-serving cell (Cell_2), for example, because a handover to the non-serving cell (cell_2) is becoming increasingly probable or possible, or for other reasons.

[0301] DU 132_1 of the first cell (Cell_1), which has determined 60 to trigger LTM for the second non-serving cell (Cell_2), sends a trigger 13 to the user equipment 110. This trigger is used to select a specific DRB for data transmission. Trigger 13 is a MAC control element for LTM of the second cell (Cell_2).

[0302] DU 132_1 of the first serving cell (Cell_1) directly or indirectly notifies 57 DU 132_2 of the second non-serving cell (Cell_2) that a specific DRB has been triggered for the data transmission. In this example, DU 132_1 of the first serving cell (Cell_1) notifies 75 CU 134, and CU 134 notifies 77 DU 132_2.

[0303] Alternatively, in some examples, user equipment 110 may inform DU 132_2 of the second non-serving cell (Cell_2) that a specific DRB has been triggered for the data transmission.

[0304] exist Figure 12C In FIG, two different scenarios are illustrated. In scenario 90_1, a first data radio bearer (DRB_1) is unavailable. A trigger 13 enables data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using a second data radio bearer configuration 10_2.

[0305] In scenario 90_2, a first data radio bearer (DRB_1) is available. A trigger 13 enables data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using the first data radio bearer configuration 10_1.

[0306] Second embodiment

[0307] Figure 12A 、 Figure 12B 、 Figure 12C Different examples of the second embodiment are illustrated.

[0308] refer to Figure 12A , the process optionally includes the establishment of Low Layer Triggered Mobility (LTM) 24 as described above.

[0309] The procedure comprises a 'configuration phase' downlink signalling 11 which provides a first data radio bearer configuration 10_1 for the second cell 120_2 and a second data radio bearer configuration 10_2 for the second cell 120_2.

[0310] The process includes an 'event phase', where an event causes a trigger 13 to be transmitted to the user equipment 110. In this example, the event is a change in the availability state of a data transfer session (DTS), for example, the data transfer session becomes available or becomes unavailable.

[0311] The process comprises a 'triggering phase', wherein a trigger is sent by the apparatus 120_1 of the first cell (Cell_1) to the user equipment 110.

[0312] exist Figure 11A , the process comprises a handover phase 26 followed by data transmission 15. As previously described, this comprises performing data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using the first data radio bearer configuration 10_1 if the trigger 13 indicates the use of the first data radio bearer configuration 10_1, or performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2 if the trigger 13 indicates the use of the second data radio bearer configuration 10_2.

[0313] In some, but not necessarily all, examples, the first data radio bearer and the second data radio bearer have different characteristics, such as bandwidth, latency, reliability, and / or quality of service.

[0314] In at least some examples, trigger 13 enables the user device to create an operational map 14, as previously described.

[0315] The data transfer session 12 is mapped to a subset of the set of a plurality of pre-configured data radio bearers (DRBs) by an operational mapping 14 for data transfer.

[0316] exist Figure 12B In , the LTM establishment phase and configuration phase are merged.

[0317] The user equipment sends a measurement report 41 to the apparatus 120_1 of the first cell (Cell_1).

[0318] The device 120_1 of the first serving cell (Cell_1) communicates 51 directly or indirectly with the device 120_2 of the second non-serving cell (Cell_2) to establish LTM with 'persistence' of DRB.

[0319] The apparatus 120_2 of the second non-serving cell (Cell_2) communicates 53 directly or indirectly with the apparatus 120_1 of the first serving cell (Cell_1) to identify low-layer resources for pre-activation DRB provision.

[0320] The apparatus 120_1 sends a configuration message 11 to the user equipment 110, which configures the persistence of the DRB configuration at the UE 110. This enables the storage of the first DRB configuration 10_1 and the second DRB configuration 10_2, as previously described.

[0321] There is currently no available data transfer session mapped to at least one of the DRBs (e.g., the first DRB_1). This DRB is not currently part of the available mapping for data transfer and cannot be used for data transfer, but is still stored for future use in response to the received trigger 13. This storage for future use when currently unusable is 'persistent'.

[0322] The user equipment 110 sends an acknowledgement 43 to the configuration message 11 .

[0323] There is communication 141, 142 for establishing a data transfer session (DTS). The UE sends a message 141 requesting establishment of a data transfer session and may indicate a predicted service. If available, a second data radio bearer (DRB_2) is established for the new data transfer session (DTS).

[0324] The user equipment sends a measurement report 45 to the apparatus 120_1 of the first cell (Cell_1).

[0325] The apparatus 120_1 of the first cell (Cell_1) determines 60 based on the measurement report 45 that LTM is to be triggered for the second non-serving cell, for example, because a handover to the non-serving cell (cell_2) is becoming increasingly probable or possible, or for other reasons. It also determines to use proactive low layer provisioning (second DRB configuration) for the new data transmission session in cell 2.

[0326] The apparatus 120_1 of the first cell (Cell_1) has determined 60 that an LTM is to be triggered for the second non-serving cell and sends a trigger 13 to the user equipment 110. The trigger is used to determine whether a new data transmission session is supported.

[0327] The device 120_1 of the first serving cell (Cell_1) notifies 57 the device 120_2 of the second non-serving cell (Cell_2) directly or indirectly that a specific DRB (DRB_2) has been triggered for a new data transmission session.

[0328] Alternatively, in some examples, user equipment 110 may inform apparatus 120_2 of a second non-serving cell (Cell_2) that a specific DRB (DRB_2) has been triggered for a new data transmission session.

[0329] Figure 12C Further details of example implementations are illustrated in Reference numerals from previous figures are reused to indicate the same or similar features.

[0330] exist Figure 12C In , the LTM establishment phase and configuration phase are merged.

[0331] The device 120_1 of the first cell is a first DU 132_1 in communication with the CU 134. The device 120_2 of the second cell is a second DU 132_2 in communication with the CU 134.

[0332] The user equipment sends a measurement report 41 to the first DU 132_1 of the first cell (Cell_1).

[0333] A first DU 132_1 of a first serving cell (Cell_1) indirectly communicates 51 with a second DU 132_2 of a second non-serving cell (Cell_2) via a CU 134 to establish LTM with 'persistence' of the DRBs. In this example, the communication 51 includes sending 71 a measurement report from the first DU 132_1 to the CU 134. The CU 134 determines 64 that LTM is to be triggered. The CU 134 sends a UE content modification request 73 related to LTM for cell 2 to the DU 132_2 of the second cell (cell_2). This notifies the DU 132_2 of the DRBs for cell 2 (e.g., first data radio bearer DRB_1, second data radio bearer DRB_2). The request 73 has a special format that indicates that it is requesting LTM with maintenance (persistence) of the DRB configuration.

[0334] DU 132_2 of the second non-serving cell (Cell_2) indirectly communicates 53 with DU 132_1 of the first serving cell (Cell_1) to identify low-layer resources for pre-activation DRB provisioning. DU 132_2 determines 62 the resources for the DRB specified by request 73. In this example, data radio resources are added / granted even though there is no mapped data transmission session. DU 132_2 sends a UE context setup confirmation 81 to CU 134 regarding the LTM for the second cell (Cell_2).

[0335] CU 134 sends an RRC reconfiguration message 11 to DU 132_1 of the first serving cell (Cell_1) for LTM of the second cell (Cell_2). This message indicates that the first data radio bearer DRB_1 will be added / permitted, and the second data radio bearer DRB_2 will be added / permitted. It also indicates whether they are currently mapped to available data transmission sessions. RRC reconfiguration message 11 includes a first DRB configuration 10_1 for the first DRB (DRB_1) and a second DRB configuration 10_2 for the second DRB (DRB_2).

[0336] DU 132_1 sends a configuration message 11 (RRC reconfiguration message 11) to the user equipment 110. This configures the persistence of the DRB configuration at the UE 110. This enables storage of the first DRB configuration 10_1 and the second DRB configuration 10_2 as previously described.

[0337] There is currently no available data transfer session mapped to at least one of the DRBs (e.g., the second DRB_2). This DRB is not currently part of the available mapping for data transfer and cannot be used for data transfer, but is still stored for future use in response to the received trigger 13. This storage for future use is 'persistent' when it is currently unusable.

[0338] The user equipment 110 sends an acknowledgement 43 to the configuration message 11 .

[0339] The following is the communication for establishing a data transfer session (DTS). The UE sends a message 141 requesting establishment of a data transfer session and may indicate a predicted service. If available, a second data radio bearer (DRB_2) is established for the new data transfer session (DTS).

[0340] DU 132_1 sends message 141 to CU 132 as message 151. CU 134 establishes 66 a second data radio bearer configuration 10_2 for a second data radio bearer (DRB_2) for the new data transmission session. CU 134 sends a UE context modification request 153 to DU 132_1 of the serving cell (Cell_1). Request 153 requests the use of the active DRB (DRB_2) for the new data transmission session after handover to the second cell.

[0341] The DU 132_1 of the serving cell (Cell_1) determines 62 whether the requested resource (DRB_2) is available. The DU 132_1 of the serving cell (Cell_1) sends a UE context modification response message 155 for DRB_2 to the CU 134.

[0342] CU 134 transmits RRC reconfiguration message 143 related to LTM for second cell (Cell_2) to DU 132_1 of serving cell (Cell_1). DU 132_1 of serving cell (Cell_1) transmits received RRC reconfiguration message 143 related to LTM for second cell (Cell_2) to UE 110.

[0343] The UE transmits an RRC reconfiguration complete message 157 to the DU 132_1 of the serving cell (Cell_1). The DU 132_1 of the serving cell (Cell_1) transmits the received RRC reconfiguration complete message 157 to the CU 134.

[0344] The user equipment sends a measurement report 45 to the apparatus 120_1 of the first cell (Cell_1). The measurement report is a report of layer 1 (L1) measurements performed by the user equipment 110.

[0345] The DU 132_1 of the first cell (Cell_1) determines 60 based on the measurement report 45 that LTM is to be triggered for the second non-serving cell (Cell_2), for example, because a handover to the non-serving cell (cell_2) is becoming increasingly probable or possible, or for other reasons. It also determines to use proactive low layer provisioning (second DRB configuration) for the new data transmission session in cell 2.

[0346] DU 132_1 of the first cell (Cell_1), which has determined 60 to trigger LTM for the second non-serving cell (Cell_2), sends a trigger 13 to the user equipment 110, which may provide (or not prove) an available mapping 14 for data transmission related to the new data transmission session. Trigger 13 is a MAC control element for LTM of the second cell (Cell_2).

[0347] DU 132_1 of the first serving cell (Cell_1) directly or indirectly notifies 57 DU 132_2 of the second non-serving cell (Cell_2) that the available mapping 14 has been triggered for a new data transmission session. In this example, DU 132_1 of the first serving cell (Cell_1) notifies 75 CU 134, and CU 134 notifies 77 DU 132_2. Alternatively, in some examples, user equipment 110 can notify DU 132_2 of the second non-serving cell (Cell_2).

[0348] Reference again Figure 5 There are states in which the data transmission session 12_1 is mapped to a subset (DRB_1) of a set of a plurality of pre-configured data radio bearers (DRBs), and states in which the data transmission session 12_1 is not mapped to any pre-configured data radio bearer (DRB). The states are selected by trigger 13.

[0349] As a result of the trigger 13, for the data transfer session 12_1, a DRB to data transfer session mapping 14 exists (or does not exist).

[0350] The data transmission session 12_1 is a new data transmission session 12 . Before triggering 13 , the new data transmission session has not been used for data transmission between the UE and the first cell 120_1 or the second cell 120_2 .

[0351] The first data radio bearer configuration 10 and the second data radio bearer configuration 10 are for at least a first data transmission session 12_1 and Optional The second data transmission session 12_2 configures a data radio bearer (DRB). If the trigger 13 indicates the use of the first data radio bearer configuration 10_1, performing data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1 includes: not using the first data radio bearer configuration 10_1 implement a second data transmission session 12_2, and

[0352] Performing a data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2 if the trigger 13 indicates usage of the second data radio bearer configuration 10_2 includes performing a second data transmission session 12_2 with the second data radio bearer configuration 10_2.

[0353] The described examples include an example of an apparatus 120 (132) for a cellular telecommunications network, the apparatus comprising:

[0354] For transmitting downlink signaling 11 to a user equipment (UE) via the first cell 120_1

[0355] The transmission component of 110 , the downlink signaling provides a first data radio bearer configuration 10_1 (DRB_1) for the second cell 120_2 and a second data radio bearer configuration 10_2 (DRB_2) for the second cell 120_2 ;

[0356] Components for causing a trigger 13 to be transmitted to a user equipment (UE) 110 via the first cell 120_1, the trigger being configured to indicate use of a first data radio bearer configuration 10_1 to enable data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer (DRB_1), or being configured to indicate use of a second data radio bearer configuration 10_2 to enable data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer (DRB_2).

[0357] In some but not necessarily all examples, the apparatus 120 (132) is configured to receive 53 a configuration of a first data radio bearer configuration 10_1 for the second cell 120_2 and a configuration of a second data radio bearer configuration 10_2 for the second cell 120_2 to enable downlink signaling 11 of the first data radio bearer configuration 10_1 (DRB_1) for the second cell 120_2 and the second data radio bearer configuration 10_2 (DRB_2) for the second cell 120_2.

[0358] In some but not necessarily all examples, the apparatus 120 (132) is configured to receive 53 a decision criterion (for a decision process 60) for causing a trigger 13 to be transmitted to a user equipment (UE) 110 via the first cell 120_1 and / or setting a mapping parameter in the trigger.

[0359] The decision criteria for using the first DRB configuration 10_1 or the second DRB configuration 10_2 may include at least one of the following:

[0360] a. Availability of Data Radio Bearers (DRBs) at the first cell 120_1

[0361] b. Availability of Data Radio Bearers (DRBs) at the second cell 120_2

[0362] c. New data transfer session

[0363] In some but not necessarily all examples, the apparatus 120 (132) is configured to receive and use a report 45 comprising information for comparison with decision criteria in the decision process 60 for causing the transmission of the trigger 13 to the user equipment (UE) 110 via the first cell 120_1 and / or setting mapping parameters in the trigger.

[0364] In some, but not necessarily all, examples, the apparatus 120 (132) is configured to receive and use a report 55 from the second cell 120_2 indicating the availability of DRBs at the second cell 120_2 for comparison with the decision criteria. The report 55 may be a periodic report or an event-based report indicating a load status of DRB allocations for the UE.

[0365] Report 55 may indicate the lack of resources or the presence of resources for DRB configuration.

[0366] Figure 13AAn example of a controller 400 suitable for use with devices 110, 120 (132) is shown. Controller 400 may be implemented as controller circuitry. Controller 400 may be implemented solely in hardware, have certain aspects in software including only firmware, or may be a combination of hardware and software (including firmware).

[0367] like Figure 13A As shown in , the controller 400 can be implemented using instructions that enable hardware functions, for example, by using executable instructions of a computer program 406 in a general or special purpose processor 402, which executable instructions can be stored on a computer-readable storage medium (disk, memory, etc.) for execution by such processor 402.

[0368] The processor 402 is configured to read from and write to the memory 404. The processor 402 may also include an output interface via which data and / or commands are output by the processor 402 and an input interface via which data and / or commands are input to the processor 402.

[0369] The memory 404 stores a computer program 406, which includes computer program instructions (computer program code) that control the operation of the apparatus 110, 120 (132) when loaded into the processor 402. The computer program instructions of the computer program 406 provide the logic and routines that enable the apparatus to perform the methods shown in the accompanying drawings. The processor 402 can load and execute the computer program 406 by reading the memory 404.

[0370] The device 110, 120 (132) includes:

[0371] at least one processor 402; and

[0372] at least one memory 404 comprising computer program code,

[0373] The at least one memory 404 and the computer program code are configured to, together with the at least one processor 402, cause the apparatus 110, 120 (132) to at least perform:

[0374] Data transmission 15 is conditionally performed between a user equipment (UE) 110 and a second cell 120_2, wherein

[0375] if the trigger 13 received from the first cell 120_1 indicates use of the previously received and stored first data radio bearer configuration 10_1, causing data transmission 15 to be performed between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1, and

[0376] If the trigger 13 received from the first cell 120_1 indicates the use of the previously received and stored second data radio bearer configuration 10_2, data transmission 15 is caused to be performed between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2.

[0377] The device 110, 120 (132) includes:

[0378] at least one processor 402; and

[0379] at least one memory 404 comprising computer program code,

[0380] The at least one memory stores instructions that, when executed by the at least one processor 402, cause the apparatus to at least:

[0381] Data transmission 15 is conditionally performed between a user equipment (UE) 110 and a second cell 120_2, wherein

[0382] if the trigger 13 received from the first cell 120_1 indicates use of the previously received and stored first data radio bearer configuration 10_1, causing data transmission 15 to be performed between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1, and

[0383] If the trigger 13 received from the first cell 120_1 indicates the use of the previously received and stored second data radio bearer configuration 10_2, data transmission 15 is caused to be performed between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2.

[0384] like Figure 13B As shown in , the computer program 406 may arrive at the apparatus 110, 120 (132) via any suitable delivery mechanism 408. The delivery mechanism 408 may be, for example, a machine-readable medium, a computer-readable medium, a non-transitory computer-readable storage medium, a computer program product, a memory device, a recording medium (such as a compact disc read-only memory (CD-ROM) or a digital versatile disc (DVD) or a solid-state memory), an article of manufacture including or tangibly embodying the computer program 406. The delivery mechanism may be a signal configured to reliably transmit the computer program 406. The apparatus 110, 120 (132) may propagate or transmit the computer program 406 as a computer data signal.

[0385] Computer program instructions for causing an apparatus to at least perform the following operations or for performing the following operations:

[0386] Data transmission 15 is conditionally performed between a user equipment (UE) 110 and a second cell 120_2, wherein

[0387] if the trigger 13 received from the first cell 120_1 indicates use of the previously received and stored first data radio bearer configuration 10_1, causing data transmission 15 to be performed between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1, and

[0388] If the trigger 13 received from the first cell 120_1 indicates the use of the previously received and stored second data radio bearer configuration 10_2, data transmission 15 is caused to be performed between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2.

[0389] The computer program instructions may be included in a computer program, a non-transitory computer readable medium, a computer program product, a machine readable medium. In some, but not necessarily all, examples, the computer program instructions may be distributed across more than one computer program.

[0390] Although memory 404 is illustrated as a single component / circuitry, it may be implemented as one or more separate components / circuitry, some or all of which may be integrated / removable and / or may provide persistent / semi-persistent / dynamic / cache storage.

[0391] The memory may include, for example, ROM and / or RAM and / or EEPROM and / or DRAM and / or SRAM and the like.

[0392] Memory can be computer memory, a device used to temporarily or permanently store data or programs (sequences of instructions) for use by electronic digital computers. Computers represent information using binary code (written as sequences of 0s and 1s). Each binary digit (or "bit") can be stored by any physical system that can be in one of two stable states (representing 0 and 1).

[0393] Computer memory is divided into primary (or main) memory and secondary (or auxiliary) memory. Primary memory holds instructions and data while programs are being executed, while secondary memory holds data and programs that are not currently in use and provides long-term storage.

[0394] While the primary / secondary memory distinction is very useful, memory organization in computers forms a hierarchy, from very small, fast, and expensive registers in the CPU to small, fast cache memory; larger DRAM; very large hard disks; and slow and inexpensive nonvolatile backup storage. Modern computer operating systems' memory usage spans these levels with virtual memory, a system that provides programs with a large address space (addressable memory) that can exceed the actual RAM in the computer. Virtual memory provides each program with a portion of primary memory and stores the rest of the code and data on the hard disk, automatically copying blocks of addresses to and from primary memory as needed. Virtual memory is made possible by the speed of modern hard disks and the same locality of reference property that makes caches work.

[0395] Although processor 402 is illustrated as a single component / circuitry, it may be implemented as one or more separate components / circuitry, some or all of which may be integrated / removable.Processor 402 may be a single-core or multi-core processor.

[0396] Figure 14 An example of a network 100 is shown that includes multiple network nodes, including terminal nodes 110, access nodes 120, and one or more core nodes 129. Terminal nodes 110 and access nodes 120 communicate with each other. One or more core nodes 129 communicate with access nodes 120.

[0397] In this example, the network 100 is a wireless telecommunications network in which at least some of the terminal nodes 110 and access nodes 120 communicate with each other using reception / reception of radio waves.

[0398] In some examples, one or more core nodes 129 can communicate with each other. In some examples, one or more access nodes 120 can communicate with each other.

[0399] The network 100 may be a cellular network comprising a plurality of cells 122, each served by an access node 120. In this example, the interface between the terminal node 110 and the access nodes 120 defining the cells 122 is a wireless interface 124.

[0400] The access node 120 is a cellular radio transceiver. The terminal node 110 is a cellular radio transceiver.

[0401] In the example shown, the cellular network 100 is a Third Generation Partnership Project (3GPP) network, where the terminal nodes 110 are user equipments (UEs) and the access nodes 120 are base stations.

[0402] In the particular example shown, network 100 is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). E-UTRAN consists of E-UTRAN NodeBs (eNBs) 120 that provide E-UTRA user plane and control plane (RRC) protocol terminations towards UE 110. The eNBs 120 are interconnected via an X2 interface 126. The eNBs are also connected to a Mobility Management Entity (MME) 129 via an S1 interface 128.

[0403] In another example, network 100 is a next generation (or new radio NR) radio access network (NG-RAN). NG-RAN consists of gNodeBs (gNBs) 120 to provide user plane and control plane (RRC) protocol terminations towards UE 110. gNBs 120 are interconnected with each other via X2 / Xn interfaces 126. The gNBs are also connected to an access and mobility management function (AMF) via an N2 interface 128.

[0404] User equipment includes mobile devices. Where reference is made to user equipment, whenever possible, the reference includes and encompasses reference to mobile devices.

[0405] Figure 15 An example of a method 500 is illustrated. The method 500 may be performed by the user equipment 110.

[0406] The method includes, at block 502 , receiving downlink signaling 11 via the first cell 120_1 , the downlink signaling providing a first data radio bearer configuration 10_1 (DRB_1) for the second cell 120_2 and a second data radio bearer configuration 10_2 (DRB_2) for the second cell 120_2 .

[0407] The method includes, at block 504 , storing a first data radio bearer configuration 10_1 for performing data transmission 15 via the second cell 120_2 using a first data radio bearer (DRB_1), and storing a second data radio bearer configuration 10_2 for performing data transmission 15 via the second cell 120_2 using a second data radio bearer (DRB_2).

[0408] The method includes: at block 506 , receiving a trigger 13 via the first cell 120_1 ;

[0409] The method includes, at block 502 , conditionally performing data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using a data radio bearer configuration 10 .

[0410] If the trigger 13 indicates the use of the first data radio bearer configuration 10_1 , the method 500 performs data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1 .

[0411] If the trigger 13 indicates use of the second data radio bearer configuration 10_2, the method 500 includes performing a data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10-2.

[0412] In some, but not necessarily all, examples, performance of data transmission 15 between a user equipment (UE) 110 and a second cell requires operational mapping 14 between available data transmission sessions 12 to provide data for transmission and available data radio bearers (DRBs) to provide a transmission channel for the data.

[0413] At the time of downlink signaling 11, there is no mapping 14 of the second cell 120_2 between a data radio bearer (DRB) for the second cell 120_2 and a data transmission session 12. At the time of triggering the execution of a data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the data radio bearer (DRB) for the second cell 120_2 as a result of the received trigger 13, there is an operational mapping 14 of the second cell 120_2 between the data radio bearer (DRB) for the second cell 120_2 and the data transmission session 12.

[0414] In some examples, at the time of downlink signaling 11, a data radio bearer (DRB) for second cell 120_2 is not available for second cell 120_2, while at the time of triggering, a data radio bearer (DRB) for second cell 120_2 is available for second cell 120_2, for example, a data transmission session 12 is available for second cell 120_2 and a data radio bearer (DRB) is not available for second cell 120_2.

[0415] In some examples, at the time of triggering, the data transmission session 12 is available for the second cell 120_2, while at the time of signaling, the data transmission session 12 is not available for the second cell 120_2, e.g., the data transmission session 12 is not available for the second cell 120_2 and a data radio bearer (DRB) is not available for the second cell 120_2.

[0416] The preceding paragraphs describe a user equipment (UE) 110, which includes:

[0417] at least one processor 402; and

[0418] at least one memory 404 comprising computer program code,

[0419] The at least one memory stores instructions that, when executed by the at least one processor 402, cause the apparatus to at least:

[0420] If the trigger 13 received from the first cell 120_1 indicates the previously received and stored first data radio bearer configuration 10_1 use , then data transmission 15 is performed between the user equipment (UE) 110 and the second cell 120_2 using the first data radio bearer configuration 10_1, and

[0421] If the trigger 13 received from the first cell 120_1 indicates the previously received and stored second data radio bearer configuration 10_2 use , then data transmission 15 is performed between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2.

[0422] The preceding paragraphs describe a user equipment (UE) 110, which includes:

[0423] The receiver circuitry is configured to receive, via the first cell 120_1, solely:

[0424] downlink signaling 11, the downlink signaling providing a first data radio bearer configuration 10_1 (DRB_1) for the second cell 120_2 and a second data radio bearer configuration 10_2 (DRB_2) for the second cell 120_2,

[0425] Trigger 13;

[0426] a memory circuitry configured to store a first data radio bearer configuration 10_1 for performing a data transmission 15 via the second cell 120_2 using a first data radio bearer (DRB_1), and to store a second data radio bearer configuration 10_2 for performing a data transmission 15 via the second cell 120_2 using a second data radio bearer (DRB_2);

[0427] The control circuit system is configured to trigger 13 in the user equipment (UE) according to the received

[0428] 110 performs data transmission 15 with the second cell 120_2,

[0429] wherein the control circuitry is configured to: if a trigger 13 indicates use of the first data radio bearer configuration 10_1, perform data transmission 15 between a user equipment (UE) 110 and a second cell 120_2 using the first data radio bearer configuration 10_1, and

[0430] The control circuitry is configured to, if the trigger 13 indicates use of the second data radio bearer configuration 10_2 , perform data transmission 15 between the user equipment (UE) 110 and the second cell 120_2 using the second data radio bearer configuration 10_2 .

[0431] Low Layer Triggered Mobility (LTM) (also known as L1 / 2 inter-cell mobility) is one of the targets for mobility enhancement in 3GPP Rel. 18. In LTM, decisions on cell changes are based on L1 measurements and are made in the MAC layer of a distributed unit (DU).

[0432] In LTM, the target node can generate a full or incremental configuration for a candidate target PCell or PSCell, respectively. In the case of an incremental configuration, the configuration of the candidate target cell only contains the parameters that need to be modified (affected by the change) compared to the current source cell. Therefore, the size of the incremental configuration can be much smaller than the size of the full configuration, which significantly reduces the overhead on the radio interface.

[0433] In case the radio bearer configuration is provided as a delta configuration, any update to the UE's radio bearer configuration needs to be propagated to all prepared target cells to provide updated delta configurations of their corresponding radio bearer configurations.

[0434] When a new bearer is configured for an RRC connection or a QoS flow (data transfer session) is created, an RRC reconfiguration message containing the modified DRB configuration is provided to the UE. The delay for activating the new bearer depends on the time required to reconfigure the UE. In an LTM scenario, if the DRB configuration of the serving cell is updated, the LTM configuration of the target cell (stored by the UE) also needs to be modified to reflect the change in the radio bearer configuration. This is necessary so that after LTM is performed, these configurations are consistent between the UE and the target node.

[0435] In the case of overload, DRB may be rejected during LTM preparation. The above example (embodiment 1) mitigates its adverse consequences.

[0436] Problem 2: The above example (Embodiment 2) reduces the signaling delay and internal signaling overhead generated when creating a new data transmission session.

[0437] The provided examples enhance low-layer resource provisioning on the target DU (non-serving cell) side during LTM preparation.

[0438] Example 1:In the event of an overload condition during LTM preparation, the target DU provides lower-layer resources for DRBs that were not available at the time of LTM preparation. As a fallback, it also allocates a default DRB. The load condition at the target DU is indicated to the source DU to inform the source DU whether it can provide proactive lower-layer resources during LTM execution. If the overload condition is remedied at the target DU, the source DU instructs the UE to use lower-layer resources for DRBs. Otherwise, the source DU instructs the UE to use the default DRB for the QoS flow (data transmission session).

[0439] exist Figure 11C In Figure 1, the UE is initially in an RRC connected state with the source DU in Cell_1, where three DRBs are mapped to different QoS flows (data transfer sessions). UE 110 is configured with measurement reports, which are used to report potential target cells to the CU 134. CU 134 is aware of the QoS requirements of the QoS flows. The QoS requirements indicate that a minimum interruption time for each QoS flow should be maintained. CU 134 can determine, if possible, that interruption of the DRBs mapped to these QoS flows (data transfer sessions) should be minimized or avoided altogether.

[0440] CU 134 determines 64 that LTM should be prepared for UE 110 in Cell_1. CU 134 indicates 73 LTM preparation to target DU 1 for Cell_2, and also indicates that it wishes to use the "maintain RB configuration" feature. This indication triggers the maintenance of the DRB configuration even in the event of an overload at target DU 132_2. (The target DU and source DU can be the same node.) The target DU also includes the default DRB in the configuration.

[0441] The UE 110 is configured with LTM configuration 11 and reports target cell L1 measurements. The source DU 132_1 monitors 60 the L1 measurements and triggers a cell change to Cell_2 with a MAC CE command (trigger 13).

[0442] In option 1 (90_1): If there are no available radio resources to grant DRB2 and DRB3, the source cell (Cell_1) will instruct UE 110 to use the default DRB instead of DRB2 or DRB3 - this will update the DRB to QoS flow mapping on the UE side. In other words, the QoS flows mapped to DRB2 and DRB3 will be mapped to the default DRB.

[0443] In option 2 (90_2): If there are available radio resources, the source cell will instruct the UE to use DRB2 and DRB3. Available radio resources may occur due to UE 110 completing the session and releasing the use of existing radio resources. At this time, target DU 132_2 may prioritize the allocation and reservation of radio resources for UE 110 with LTM configuration and indicate the resource status to the CU.

[0444] Radio resource availability indications 83, 85 may be sent on a periodic or event-triggered basis, such as a UE disappearing from a cell enabling the availability of new radio resources. Similarly, high priority UEs may preempt radio resource reservations for LTM UEs, which may result in an indication of unavailable radio resources to the CU 134.

[0445] After either option, the source DU 132_1 will indicate 75 the selected DRB to QoS flow mapping to the CU 134, which in turn will inform 77 the target DU about the final UE configuration.

[0446] As an alternative to these steps, UE 110 may also report the latest DRB configuration to target node 132_2.

[0447] As an alternative to the above, UE 110 may also report the latest DRB configuration to CU 134, which may then inform target DU 132_2 about the final UE configuration.

[0448] In another alternative, messages 8 and 9 or 15 and 16 specify the serving DU behavior, i.e., if it cannot be reported, the serving DU must map the QoS flow to the default DRB. In this case, the target DU can use the last sent DRB load status to infer the UE's DRB configuration. However, this situation may cause a race condition, which the above alternative can avoid.

[0449] Example 2: At the time of LTM preparation, the target DU can provide active lower layer resources for DRBs that are not mapped to any specific QoS flow at that time. The LTM configuration is configured for the UE with active lower layer resources for DRBs that are not mapped to any specific QoS flow. The UE can add new QoS flows while the LTM configuration is maintained on the UE side. The new QoS flow generates a new DRB at the serving cell, but the candidate LTM configuration remains unchanged. If there is a new LTM configuration, the LTM configuration will not be updated. At the time of LTM execution, the source DU instructs the UE to map the new QoS flow to the active DRB at the target cell.

[0450] exist Figure 12CIn Figure 1, the UE is in an RRC connected state with a source DU in Cell_1, where one DRB is mapped to a QoS flow. UE 110 is configured with measurement reports that report potential target cells to CU 134. UE 110's service requirements and associated QoS requirements are known to CU 134. The QoS requirements indicate that a minimum interruption time for each QoS flow should be maintained. CU 134 can determine that interruption of DRBs mapped to these QoS flows should be minimized or avoided entirely, if possible.

[0451] CU 134 determines 64 that LTM should be prepared for the UE in Cell_1. CU 134 indicates LTM preparation to target DU2 for Cell_2, and also indicates that it wishes to use the "active RB configuration" feature. Target DU_2 adds a DRB configuration that is not mapped to any QoS flow. This indication triggers the addition of lower layer resources for the active DRB configuration at the target DU. Source DU 132_1 is aware that these DRBs should not be used by UE 110 unless a QoS flow is later added to attach to them.

[0452] The UE 110 is configured 11 with LTM configuration and reports 45 target cell L1 measurements. The source DU 132_1 monitors 60 the L1 measurements 45.

[0453] At the same time, UE 110 requests 141, 151 to establish a new PDU session (data transfer session), and the network establishes 66 a DRB configuration for QoS flow 1 (the QoS flow associated with the newly established PDU session); PDU = Packet Data Unit. CU 134 indicates to source DU 132_1 that, in the event of a handover to Cell_2, the new QoS flow should be mapped to the DRB configuration provided for UE 110 by target DU 132_2 (in the example of DRB2 and DRB3). However, the LTM configuration is not updated.

[0454] Later, UE measurements 45 are used to trigger 13 a cell change with a MAC CE command 13 towards UE 110. By means of the MAC CE command 13, the source cell (Cell_1) will instruct UE 110 to update the DRB to QoS flow mapping 14 on the UE side, i.e. map QoS flow 1 to the active DRB.

[0455] Source DU 132_1 will indicate 75 the selected DRB to QoS flow mapping to CU 134, which in turn will notify 77 the target DU of the final UE configuration. As an alternative to these steps, UE 110 can also report the latest DRB configuration to target node 132_2. As an alternative to the above, UE 110 can also report the latest DRB configuration to CU 134, which can then notify target DU 132_2 of the final UE configuration.

[0456] In another alternative, after the addition of the new DRB for the UE (after 153), CU 134 indicates the DRB to QoS flow mapping 14 to the target DU, but UE 110 is not updated with the new LTM configuration. Therefore, there is no need to indicate the latest DRB configuration to the target DU.

[0457] These examples avoid modification of the conditional configuration if the configuration of the UE 110 in the serving cell is changed.

[0458] These examples are expected to result in specification changes to TS 38.331 and TS 38.423.

[0459] The above embodiments have been described as exemplary embodiments. Their features have broad applicability, as will become apparent from, for example, the description of another exemplary embodiment. Specific features of one embodiment may also be used in another embodiment.

[0460] FIG. 16 generally illustrates an exemplary embodiment relating to the configuration and use of DRBs in a radio access network.

[0461] The present invention also relates to a user equipment (UE), the UE being configured to be connected to a first cell of a first network node supporting a distributed unit (DU) functionality and / or layer 2 protocol processing of a radio access network (RAN), the UE comprising:

[0462] at least one processor; and

[0463] at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least:

[0464] Establishing a connection with the first cell,

[0465] sending data to the first cell using at least a first data radio bearer,

[0466] performing L3 measurements on at least one candidate target cell of a plurality of candidate target cells to potentially hand over to,

[0467] sending an L3 measurement report relating to the performed measurements to a second network node, the second network node supporting a Central Unit CU functionality and / or a layer 3 protocol processing of a Radio Access Network RAN and being connected to the first node,

[0468] receiving an L3 configuration message, the L3 configuration message including configuration information related to at least one candidate target cell among the plurality of candidate target cells for L1L2 triggered mobility LTM, wherein the configuration information includes a pre-configuration for potentially using a second data radio bearer different from the first data radio bearer to send data to the target cell to be handed over; and

[0469] receiving an L2 message including a trigger for handover from a first cell to a target cell and an implicit or explicit indication of whether a preconfigured data radio bearer is to be used to send data to the target cell and / or whether a currently used first data radio bearer is to be retained and used to send data to the target cell,

[0470] Establish a connection with the indicated target cell,

[0471] Data is sent to the target cell using at least the indicated data radio bearer.

[0472] Such a user equipment may also cover one or more features of the other embodiments described so far.

[0473] Returning to FIG. 16 , the user equipment UE may be configured to connect to the radio access network, wherein the indicated target cell is a cell of a third network node supporting distributed unit DU functionality and / or layer 2 protocol processing of the radio access network RAN.

[0474] The user equipment UE may further be configured to connect to the radio access network, wherein the third network node is connected to the second network node.

[0475] The user equipment UE may also be configured to connect to the radio access network, wherein the L3 configuration message is an RRCConfiguration message or an RRCReconfiguration message.

[0476] The user equipment UE may also be configured to connect to the radio access network, wherein the L2 message is a MAC CE message.

[0477] The user equipment UE may also be configured to:

[0478] sending data to the first cell using a third data radio bearer, and

[0479] The configuration information includes: a configuration for maintaining the use of the third data radio bearer to send data to the target cell to be handed over.

[0480] The user equipment UE may also be configured to connect to a radio access network, wherein

[0481] An implicit or explicit indication of whether the pre-configured data radio bearer is to be used is received as part of the received L2 message.

[0482] The user equipment UE may also be configured to connect to a radio access network, wherein

[0483] Whether the preconfigured data radio bearer is to be used is implicitly or explicitly indicated by

[0484] At least one of the following ways:

[0485] - there is no indication that a preconfigured data radio bearer is to be used,

[0486] - a flag or specific instruction to use a preconfigured data radio bearer,

[0487] - a flag or specific instruction to reserve the first data radio bearer,

[0488] - A flag or specific instruction to use the preconfigured data radio bearer and reserve the first data radio bearer.

[0489] The user equipment UE may also be configured to connect to a radio access network, wherein

[0490] The configuration information further includes an instruction for sending data to the target cell to be handed over using a preconfigured second data radio bearer instead of the first data radio bearer if no further instruction for reserving the first data radio bearer for sending data to the target cell to be handed over is received.

[0491] The user equipment UE may also be configured to connect to a radio access network, wherein

[0492] The configuration information includes a preconfiguration for potentially using a second data radio bearer with a specific QoS level, and an implicit or explicit indication that the preconfigured data radio bearer with its specific QoS level is to be used to send data to the target cell, and the first data radio bearer and its assigned QoS are to be retained for sending data to the target cell.

[0493] The user equipment UE may also be configured to connect to a radio access network, wherein

[0494] There is a difference between a specific QoS level and an assigned QoS level.

[0495] The user equipment UE may also be configured to connect to a radio access network, wherein

[0496] The implicit or explicit indication indicates that data is sent to the target cell using a preconfigured data radio bearer in the first PDU session and the first data radio bearer is reserved, and is a QoS mapping for the second PDU session, wherein the first PDU session and the second PDU session are different sessions.

[0497] An illustrative example of a user equipment and a radio access network is further shown in Figure 16. For example, the radio access network may be an LTE, 5G, NR (New Radio) network or portions thereof, or a hybrid network, sometimes also referred to as multi-RAT.

[0498] The radio access network may include at least one gNB supporting, for example, L2 and L3 protocol functionalities, or a split architecture with separate network nodes, for example, at least one network node supporting distributed unit (DU) and / or in particular layer 2 (L2) protocol functionalities, and at least one other network node supporting central unit (CU) functionalities and / or in particular layer 3 (L3) protocol functionalities.

[0499] The UE of FIG16 has been connected to serving cell 1 controlled / supported by serving DU0.

[0500] To be in this mode of operation, the UE first (not shown in step 0) establishes a connection with a first cell 1. This cell then becomes the source cell and / or serving cell, which transmits and receives data and control signals to and from the UE.

[0501] When connected to cell 1, the UE sends data to the first cell using, for example, at least the first data radio bearer (e.g., DRB1, DRB2, and DRB3); DRB = Data Radio Bearer. Which DRBs are being used is configured during connection establishment or updated after the connection is established based on the UE's needs, such as which services are requested, which quality of service, etc. For example, a UE wishing to make a phone call may require additional DRBs than a UE wishing to send, for example, gaming signals, video calls, internet access, SMS, MMS, etc.

[0502] The UE may also be configured to send and / or receive control / signaling signals, eg using at least one SRB; SRB = Signaling Radio Bearer.

[0503] The UE typically performs L3 measurements on at least one candidate target cell of a plurality of candidate target cells to which it is potentially handed over. Such measurements are performed, for example, on a regular / periodic basis, or are event-driven, for example. In particular, when the connection conditions of the serving cell deteriorate, these measurements help to prepare and support handover to another cell with expected better connection conditions. The UE measurements are, for example, related to the reference signals of the cell (e.g., neighboring cell, target cell). In LTE, those reference signals used for measurement are, for example, synchronization signals and / or CRS (cell-specific reference signals). In NR, the types of reference signals are, for example, synchronization signals / PBCH reference signals and CSI-RS.

[0504] The UE generates a measurement report indicating, for example, a cell ID and relevant measurement results, and in step 1, sends an L3 measurement report related to the performed measurements to a second network node supporting a Central Unit (CU) functionality and / or layer 3 protocol processing of a radio access network (RAN) and connected to the first node (e.g., a serving CU).

[0505] The measurement report may be sent using an RRC message.

[0506] The serving CU receives and analyzes the measurement report. This analysis may result in different actions, for example, no action is taken regarding potential handover or potential handover preparation of the UE because the connection conditions to cell 1 are still good. And for example, waiting for the next measurement report. If the conditions to cell 2 are, for example, (much) better than the conditions to cell 1, the serving CU may decide to prepare for handover or conditional handover. This may be an L3 handover or an L2 handover. In step 2, the serving CU exemplarily determines to initiate preparation for L2 handover, for example to trigger LTM (L1L2 Triggered Mobility).

[0507] In step 3, the serving CU sends a UE context modification request to the target DU1 supporting cell 2. Cell 2 is a potential target cell to be handed over to, for example, for a UE performing a handover from cell 1 to cell 2. Cell 2 has been identified by the received L3 measurements. The serving CU is connected to and controls the target DU1 and therefore knows that DU1 supports cell 2. The measurement report can identify not only one potential cell to be handed over to, but also multiple cells, such as cell 3 (not shown) also supported by DU1 and / or cell 4 (not shown) supported by DU2 (not shown). The serving CU can then send (multiple) corresponding UE context modification requests to, for example, DU2 and / or DU1 (including cell 1 and cell 2).

[0508] The UE context modification request of step 3 may include: a request or instruction to establish or configure LTM for cell 2 (and the UE), an indication of which DRBs (e.g., DRB1, DRB2, DRB3) are currently used by the UE (connected to cell 1), and an instruction to allocate the same DRB (if available). Allocating the same DRB for both the UE-cell 1 connection and the UE-cell 2 connection has several advantages in terms of UE configuration, handover procedures, etc., and is therefore preferred.

[0509] The UE context modification request in step 3 may also include a request or instruction not to reject the request. This is different from the situation where the DU can always reject the request when the CU requests the UE context, for example, if there are no resources available for the DRB, then it will usually be rejected. Therefore, this is what has changed: not rejecting, but providing some alternative DRB, such as a DRB that does not meet QoS, will be a new behavior to be triggered by the CU.

[0510] In other words, the request or instruction for not rejecting the request may be an instruction for DU1 to check whether the requested DRB is currently available, and if so, allocate the same DRB, and if not, temporarily (pre)allocate other DRBs, but continue to monitor whether the requested DRB becomes available at a later point in time.

[0511] Therefore, different cases can be distinguished: for example, DU1 is requested to allocate DRB1, DRB2, DRB3 to potential cell 2-UE connection, DU1 determines:

[0512] a) All DRBs are available and can be allocated and assigned and the serving CU is informed of the allocation which can then configure the UEs respectively and in case of LTM the UEs are handed over to cell 2 which uses the allocated DRBs, or

[0513] b) For example, due to load conditions, potential interference or other reasons, none of the requested DRBs are available, and therefore DU1 is allocated at least one other DRB, such as DRB4

[0514] (not shown) to enable / support / maintain minimum connections, or preferably 3 other DRBs.

[0515] The serving CU can then configure the UE separately and in case of LTM the UE switches to cell 2 which uses the other allocated DRBs, or

[0516] c) Some of the requested DRBs (e.g., DRB1) are available, while others (such as DRB2 and DRB3) are not available, and therefore DU1 is allocated DRB1 and potentially at least one other DRB, such as DRBm and DRBn. The serving CU can then configure the UE separately, and in the case of LTM, the UE is handed over to cell 2 using the allocated DRBs.

[0517] When DU1 is enabled to continue monitoring whether the requested DRB becomes available at a later point in time, it may indicate this to the serving cell, thereby enabling the serving CU to update the newly available DRB to the serving DU.

[0518] For different cases a), b), and c), this may have different effects:

[0519] a) No impact, because the same DRB has already been allocated,

[0520] b) Depending on when and how many DRBs become available, this may have different effects: for example, before LLM is performed, DRB1 and DRB2 become available, but DRB3 is not, resulting in the LTM UE also maintaining DRB1 and DRB2 for the connection to cell 2, and using another DRB (if allocated) as a replacement for DRB3. This is beneficial because at least 2 DRBs can be preserved and only 1 DRB needs to be reallocated.

[0521] c) Depending on when and how many DRBs become available, this may have different effects:

[0522] For example, before LLM is executed, DRB2 and DRB3 become available, resulting in LTM UE also maintaining DRB1, DRB2 and DRB3 for the connection with cell 2, and

[0523] It is not necessary to use DRBm as a replacement for DRB2, nor is it necessary to use DRBn as a replacement for DRB3. This is beneficial because all three DRBs can be preserved.

[0524] Therefore, it may be beneficial to configure or enable DU1 to continue monitoring whether the requested DRB that could not be allocated becomes available at a later point in time.

[0525] Returning to the example of Figure 16, in step 4, DU1 determines which of the requested DRBs are available and determines that DRB1 is available, and DRB2 and DRB3 are not available. It then allocates DRB1 and DRBm (as replacements for DRB2) and DRB3 (as replacements for DRB3), and configures LTM for cell 2 (for the UE).

[0526] In step 5, the LTM configuration and the allocated DRBs are notified to the serving CU using a UE context setup confirm message. The figure shows the default DRB as an abbreviation for the allocated DRBs. In this example, the default DRBs include DRB1, DRBm, and DRBn.

[0527] DU1 further starts to monitor the availability of DRB2 and DRB3.

[0528] In step 6, the serving CU generates an RRCReconfiguration message and sends it to the UE. The RRCReconfiguration message includes the LTM configuration for cell 2 and default DRB information (for handover to cell 2, if such a handover is triggered). The RRCReconfiguration message also includes a measurement configuration for performing L1 measurements on cell 2 and reporting these measurements to the serving DU0. Based on the L1 measurements, DU0 can decide to trigger a handover.

[0529] The step 6 message may include LTM configurations for more than one cell potentially supported by more than one target DU. Therefore, the corresponding UE context modification request and establishment confirmation processing may be performed in advance.

[0530] Typically, the UE receives an L3 configuration message in step 6, the L3 configuration message including: configuration information related to at least one candidate target cell among the multiple candidate target cells for L1L2 triggered mobility LTM, wherein the configuration information includes: a pre-configuration for potentially using a second data radio bearer different from the first data radio bearer to send data to the target cell to be handed over.

[0531] The candidate target cell may be cell 2. The second DRB may be DRBm, which is different from DRB2, and may be used to replace DRB2 in case of handover.

[0532] The L3 configuration message (e.g., RRCReconfiguration message) may also include an indication to use at least the second DRB for handover, unless the report / message / trigger indicates the use of a different DRB. For example, if the second DRB = DRBm, then DRBm is used when handing over to cell 2; or if the use of DRB2 is indicated at a later point in time, then DRB2 is used.

[0533] The UE may need to be configured / enabled to support monitoring, detection and handling of such further unless indications and related operations, for example, when receiving an RRCReconfiguration message with LLM configuration, checking whether it also includes an unless trigger and taking action accordingly if a trigger is received. A UE supporting such functionality may store it in its UE capability information and send it to the serving CU during connection establishment or at a later point in time. Alternatively, such support may be mandatory for UEs supporting the latest versions of 3GPP standards (e.g., 3GPP TS38.300 and related specifications, Release 18 and above). Thus, the indication of Rel.18 support during connection establishment may already implicitly indicate to the serving CU support for handling of such further unless indications. Such support may also be implemented as an optional feature. In any case, this may only require minor modifications to 3GPP, as regular UEs may continue as usual (without checking for further unless indications), while more advanced UEs may do so.

[0534] In step 7, the UE confirms that the requested configuration has been successfully applied by sending a corresponding RRCReconfigurationComplete message to the serving CU.

[0535] Two options are described below to illustrate two case scenarios.

[0536] Option 1: No radio resources available

[0537] DU1 continues to monitor whether DRB2 and DRB3 become available. Meanwhile, the UE performs L1 measurement and sends corresponding L1 measurement report to the serving DU (step 10).

[0538] Each target DU (e.g., DU1) may send a status update (step 8) to the serving CU regarding the DRB load of DRB2 and DRB3 from time to time or on a regular or periodic basis, e.g., DRB2 and DRB3 are still unavailable. The serving DU may send a status (step 9) to the serving DU0 to inform DU0 that there is no change, e.g., DRB2 and DRB3 are still unavailable, please use the default DRB in the case of LLM to cell 2. Since there is no change, steps 8 and / or 9 may be optionally implemented.

[0539] Regarding timing: The UE is configured with DRBn and DRBm and an available DRB1. Target DU1 continues to monitor the availability of DRB2 and DRB3, for example, until it receives a RACH from the UE or receives a no-RACH connection request, or until the corresponding timer expires. This timing requirement can be implemented as an optional feature in 3GPP Rel. 18 and later versions.

[0540] Option 1: DRB2 and DRB3 are still unavailable

[0541] In step 11, DU0 determines based on the received L1 measurements that LTM is to be triggered, e.g. LLM towards cell 2 or another potential target cell / DU that has been preconfigured, and if that cell becomes the best cell to switch to due to degradation of the connectivity conditions of cell 1 and better conditions of the new target cell, the UE should switch to that cell. If cell 2 has good conditions for handover, a selection has to be made. The selection can be based on available resources / DRBs, e.g. if cell 2 has DRB1 available, while DRB2 and DRB3 are not available, but another potential target cell has DRB1, DRB2, DRB3 available, the decision can be to use the other potential target cell for LLM handover, even if the conditions of cell 2 are better than the other cell. The reason behind this is that sustainable handover can be performed and it is easier to handle since more DRBs are equal (compared to cell 1 connectivity).

[0542] In step 11, DU0 determines that cell 2 is the cell to be handed over to, and further determines that DRB2 and DRB3 are still unavailable, and therefore triggers LTM to cell 2 in step 12. This trigger may be included in a MAC CE message.

[0543] The MAC CE message may also include an indication for using the target configuration, such as "use default DRB" or "use DRB1, DRBm, and DRBn." Since there is no change, this indication may not be sent. When the LTM trigger is received, the UE uses the pre-configured configuration and establishes a connection with cell 2, for example, using RACH, RACH-free connection, sending a random access request message, etc. (not shown).

[0544] DU0 sends a message to the target DU1, which notifies that LTM to cell 2 has been triggered and may include information on which DRBs to be used, such as DRB1, DRBm and DRBn. The message may be sent directly to DU1 (if the interface is available) or indirectly via the serving DU, which forwards the message to DU1 (steps 13, 14). Receiving the message in DU1 may be another trigger for stopping monitoring the availability of DRB2 and DRB3. Alternatively, the forwarding may not be performed or may not trigger the stopping, and then, or in parallel, DU1 stops monitoring after a connection request (e.g., a random access request) is received from the UE.

[0545] Option 2: Available radio resource(s) (e.g., DRB2 and DRB3) become available before LTM triggers (no RACH is received at DU1 or RACH from UE)

[0546] DU1 continues to monitor whether DRB2 and DRB3 become available. Meanwhile, the UE performs L1 measurement and sends a corresponding L1 measurement report to the serving DU (step 17).

[0547] Each target DU (e.g., DU1) may send a status update (step 15) to the serving CU regarding the DRB load of DRB2 and DRB3 from time to time, either on a regular or periodic basis, or based on an event, such as DRB2 and DRB3 becoming available. The event-based may be configured such that the corresponding status update is sent after one of the monitored unavailable DRBs becomes available. The serving DU may send a status to the serving DU0 (step 16) to notify DU0 that DRB2 and DRB3 have become available, potentially along with an indication or instruction to use the available DRBs in the case of an LLM to cell 2. The serving CU or serving DU may be configured to determine whether the available resources can be used, such as whether the UE is reconfigured.

[0548] Regarding timing: The UE is configured with DRBn and DRBm, and DRB1 is available. Target DU1 continues to monitor the availability of DRB2 and DRB3, for example, until it receives a RACH or a no-RACH connection request from the UE, or until the corresponding timer expires. This timing requirement may be implemented as an optional feature in 3GPP Rel. 18 and later versions.

[0549] In step 18, DU0 determines that cell 2 is the cell to be handed over to, and further determines that DRB2 and DRB3 are now available and should be used, and therefore triggers LTM to cell 2 in step 19. This trigger may be included in a MAC CE message.

[0550] The MAC CE message also includes an indication for using the source configuration, such as DRB1, DRB2, and DRB3. When the corresponding LTM trigger is received, the UE cancels the pre-configured configuration and uses the source configuration instead, and establishes a connection with cell 2, such as using RACH, connecting without RACH, sending a random access request message, etc. (not shown).

[0551] DU0 sends a message to the target DU1, which notifies that LTM to cell 2 has been triggered and may include information about which DRBs to use, such as DRB1, DRB2, and DRB3. The message can be sent directly to DU1 (if the interface is available) or indirectly via the serving DU, which forwards the message to DU1 (steps 20, 21).

[0552] If DU0 decides to keep the preconfiguration and not use DRB2 and DRB3, DU0 sends a message to the target DU1, which notifies that LTM to cell 2 has been triggered and may include information which DRBs will be used, such as DRB1, DRBm and DRBn, or alternatively DRB1, DRB2, DRBn (if, for example, partially accepted).

[0553] In step 12 and / or step 19, the MAC trigger may acquire a new optional flag / indication field (e.g., in 3GPP Rel.18 and later versions) that indicates that the RB configuration is maintained, and / or that DRB2 and DRB3 are available and should therefore be used by the UE when connecting to the target DU (in addition to DRB1), and the UE already knows and uses DRB2 and DRB3 and is therefore able to maintain the RB configuration.

[0554] A similar procedure can be applied to, for example, option 3: DRB2 becomes available (but DRB3 is not available) before the LTM is triggered, e.g., step 12, the MAC trigger in Rel.18 obtains a new optional flag / indication field that indicates that DRB2 is available and should therefore be used by the UE when connecting to the target DU (in addition to DRB1 and DRBm), the UE already knows and uses DRB2 and is therefore able to maintain the RB configuration (for DRB1 and DRB2).

[0555] This can also be beneficial for all UEs, such as "old / regular" UEs: UE Rel.17 and newer UEs: from UE Rel.18 onwards, e.g.

[0556] UE Rel.17 can operate as in the prior art

[0557] UE Rel.18 will also operate as in the prior art, but in addition, monitor and check whether the MAC trigger has an additional field (a new optional flag / indication field indicating that DRB2 / DRB3 is available), and if so, adapt access to the target DU; the serving DU knows whether the UE supports Rel.17 or Rel.18, for example based on the UE capabilities, and therefore only adds the new optional field for Rel.18 UEs; the CU can / will inform the target DU whether the UE is Rel.17 or Rel.18 so that the target DU knows whether to operate according to the new procedure, for example, whether to continue monitoring the availability of DRB2 and DRB3 for UE Rel.18 (UE Rel.17) (for example, until it receives RACH from the UE).

[0558] Typically, the UE receives an L2 message that includes a trigger for switching from the first cell to the target cell (step 12, step 19), and an implicit or explicit indication indicating whether a preconfigured data radio bearer (e.g., DRBm) is to be used to send data to the target cell, and / or whether the currently used first data radio bearer (e.g., DRB2) is to be retained and used to send data to the target cell.

[0559] For example, the 'or' combination is used as described above, for example, DRBm replaces DRB2 in the case where DRB2 is not available. For example, the 'and' combination is used when the UE requires and / or requests additional resources at the same time, or when determined, for example, by the serving CU for downlink traffic. Since the UE knows both the source DRB configuration (e.g., DRB1, DRB2, DRB3) and the target DRB configuration (e.g., DRB1, DRBm, DRBn), there is no need to reconfigure the DRBs because the UE knows that there are enough DRBs (e.g., DRB1, DRB2, DRB3, DRBm, DRBn) from which it can select to use as additional resources when needed. The 'and' combination can also refer to the second embodiment described above. A mixture of the second and third embodiments is also possible. For example, in the third embodiment, different qualities of service can also be assigned to DRBs.

[0560] The UE then establishes a connection to the indicated target cell, and

[0561] Data is sent to the target cell using at least the indicated data radio bearer(s).

[0562] Such a user equipment may also cover one or more features of the other embodiments described so far.

[0563] Returning to Figure 16 , the user equipment UE can be configured to connect to a radio access network, where the indicated target cell is a cell of a third network node supporting distributed unit DU1 functionality and / or layer 2 protocol processing of the radio access network RAN. DU0, DU1, and CU can be physically collocated or separated using one or more hardware devices, such as processor 1 and memory 1 of the CU at location X, processor 2 and memory 2 of DU0 at location Y, and processor 3 and memory 3 of DU1 at location Z.

[0564] The user equipment UE may also be configured to be connected to a radio access network, wherein the third network node is connected to the second network node. Du1 may be connected to the serving CU, or may be connected to another CU, such as CU1. The serving CU and Du1 then communicate via CU1, and corresponding messages are added.

[0565] The user equipment UE may also be configured to be connected to the radio access network, wherein the L3 configuration message is an RRCConfiguration message, or an RRCReconfiguration message.One or more messages may be used to transmit one or more different information; RRC=Radio Resource Control.

[0566] The user equipment UE may also be configured to be connected to the radio access network, where the L2 message is a MAC CE message; MAC = Medium Access Control Element. Using MAC CE is advantageous because small changes are required (indication of the radio resources to be used, such as DRBs) to enable fast handover, for example based on L1 measurements, without the need to reconfigure DRBs when they become available, thereby, for example, reducing signaling effort, enabling more efficient communication and saving power. Release signaling can be used for other purposes, such as serving other UEs, etc.

[0567] The user equipment UE may also be configured to:

[0568] sending data to the first cell using a third data radio bearer, and

[0569] The configuration information includes: a configuration for maintaining the use of the third data radio bearer to send data to the target cell to be handed over.

[0570] The solution provides flexibility for adapting to different situations, which can help to better allocate resources between UEs or within a DU as soon as resources become available, and then resources can be easily reallocated. For example, if the source resources actually used are not currently available, the UE will be pre-configured (target configuration) with other available resources; but when the UE knows and uses the actual source configuration and the associated resources, it is somewhat dual-configured, and using one configuration or the other or a mixture of the two can easily be an option, for example, in the case where one or more source DRBs are available, they can be used for fast LLM switching. As long as the source connection remains stable, the DU can be configured to wait for the source configuration to become available, and then the LLM is triggered. In this way, an additional criterion for the triggering can be which resources are available. In addition, the DU can be configured to reallocate the DRBs that the DU is monitoring to become available, for example with a higher priority, thereby achieving smoother switching, for example making DRBs available where needed to enable efficient allocation and use of resources in the UE in the case of switching.

[0571] The user equipment UE may also be configured to be connected to a radio access network in which an implicit or explicit indication of whether a preconfigured data radio bearer is to be used is received as part of a received L2 message. As previously mentioned, depending on the circumstances, sending an L2 message with an LTM trigger may be sufficient to indicate which resources / DRBs to use, as they have been preconfigured and known in the UE. This may be considered an implicit indication. Alternatively, a code may be used to implement such an implicit indication using a preconfigured DRB or source DRB. The explicit indication may be implemented by indicating which DRB to use, for example DRB1, DBR2, DRBn.

[0572] The user equipment UE may also be configured to connect to the radio access network, wherein the implicit or explicit indication indicating whether the preconfigured data radio bearer is to be used is indicated in at least one of the following ways:

[0573] - there is no indication that a preconfigured data radio bearer is to be used,

[0574] - a flag or specific instruction to use a preconfigured data radio bearer,

[0575] - a flag or specific instruction to reserve the first data radio bearer,

[0576] - A flag or specific instruction to use the preconfigured data radio bearer and reserve the first data radio bearer.

[0577] The user equipment UE may also be configured to connect to the radio access network, wherein the configuration information further includes: an instruction for sending data to the target cell to be handed over using a preconfigured second data radio bearer instead of the first data radio bearer if no further instruction for reserving the first data radio bearer for sending data to the target cell to be handed over is received.

[0578] The user equipment UE may also be configured to connect to the radio access network, wherein the configuration information includes: a pre-configuration for potentially using a second data radio bearer with a specific QoS level, and an implicit or explicit indication indicating: using the pre-configured data radio bearer with its specific QoS level to send data to the target cell, and retaining the first data radio bearer and its assigned QoS to send data to the target cell.

[0579] The user equipment UE may also be configured to connect to a radio access network wherein the specific QoS level and the allocated QoS level are different.

[0580] The user equipment UE may also be configured to connect to the radio access network, wherein the implicit or explicit indication indicates that data is sent to the target cell using a preconfigured data radio bearer in the first PDU session, and the first data radio bearer is reserved, and is a QoS mapping for a second PDU session, wherein the first PDU session and the second PDU session are different sessions.

[0581] References to 'computer-readable storage medium', 'computer program product', 'tangibly embodied computer program', etc., or 'controller', 'computer', 'processor', etc. should be understood to encompass not only computers having different architectures, such as single / multi-processor architectures and sequential (von Neumann) / parallel architectures, but also special purpose circuits, such as field programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices, and other processing circuit systems. References to computer programs, instructions, code, etc. should be understood to encompass software for a programmable processor, or firmware, such as the programmable content of a hardware device, whether instructions for a processor or configuration settings for a fixed function device, gate array, or programmable logic device, etc.

[0582] As used in this application, the terms 'circuitry' and / or 'component' and / or 'processor' may refer to one or more or all of the following:

[0583] (a) Hardware circuit implementation only (such as implementation in analog and / or digital circuitry only)

[0584] as well as

[0585] (b) a combination of hardware circuitry and software such as (as applicable):

[0586] (i) a combination of analog and / or digital hardware circuits and software / firmware, and

[0587] (ii) any portion of hardware processor(s) (including digital signal processor(s)) with software, software and memory that work together to enable a device such as a mobile phone or server to perform various functions, and

[0588] (c) Hardware circuit(s) and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware)

[0589] But when software is not needed to operate, the software may not exist.

[0590] This definition of circuitry applies to all uses of this term in this application, including in any claims. As another example, as used in this application, the terms circuitry and / or 'component' and / or 'processor' also encompass an implementation of merely a hardware circuit or processor and its accompanying software and / or firmware. For example, if applicable to a particular claim element, the terms circuitry and / or 'component' and / or 'processor' also encompass a baseband integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or networking device.

[0591] The blocks shown in the figures may represent steps in a method and / or code segments in a computer program 406. The illustration of a particular order of blocks does not necessarily indicate that the blocks have a required or preferred order, and the order and arrangement of the blocks may vary. In addition, some blocks may be omitted.

[0592] There may be any number or combination of intervening elements (including no intervening elements) that are operatively coupled.

[0593] Specific components such as the receiving component may be programmed to support specific applications and / or operations such as receiving radio signals and / or processing received radio signals. The storage component may include a memory having specific data and / or configurations and / or instructions stored thereon to support specific operations and / or processing tasks.

[0594] application

[0595] The above examples apply to the following components:

[0596] Automotive systems; telecommunications systems; electronic systems, including consumer electronics; distributed computing systems; media systems for generating or writing media content, including audio, video and audiovisual content and mixed, mediated, virtual and / or augmented reality; personal systems, including personal health systems or personal fitness systems; navigation systems; user interfaces, also known as human-machine interfaces; networks, including cellular, non-cellular and optical networks; ad-hoc networks; the Internet; the Internet of Things; virtualized networks; and related software and services.

[0597] According to examples of the present disclosure, the device can be set in an electronic device, for example, a mobile terminal. However, it should be understood that the mobile terminal is merely an example of an electronic device that will benefit from the implementation of the present disclosure, and therefore, it should not be considered to limit the scope of the present disclosure to this. Although in some implementation examples, the device can be set in a mobile terminal such as a smart phone, other types of electronic devices, such as but not limited to: devices that support and / or prepare the transmission of radio signals or parts thereof and / or support the reception and / or processing of radio signals or parts thereof, mobile communication devices, portable electronic devices, wearable computing devices, portable digital assistants (PDAs), pagers, mobile computers, desktop computers, televisions, gaming devices, laptop computers, cameras, video recorders, GPS devices, and other types of electronic systems can easily adopt the examples of the present disclosure. In addition, devices can easily adopt the examples of the present disclosure regardless of their intention to provide mobility.

[0598] The following description may provide further details of alternatives, modifications and variations: The gNB includes, for example, a node that provides NR user plane and control plane protocol termination towards the UE and is connected to the 5GC via an NG interface, for example, in accordance with section 3.2 of 3GPP TS 38.300 V16.6.0 (2021-06) incorporated by reference.

[0599] The gNB Central Unit (gNB-CU) includes, for example, a logical node that hosts, for example, the RRC, SDAP, and PDCP protocols for the gNB, or the RRC and PDCP protocols for the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface with the gNB-DUs.

[0600] The gNB distributed unit (gNB-DU) includes logical nodes such as those hosting the RLC, MAC, and PHY layers of a gNB or en-gNB, and its operation is partially controlled by the gNB-CU. A gNB-DU supports one or more cells. A cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface with the gNB-CU.

[0601] The gNB-CU control plane (gNB-CU-CP) comprises, for example, a logical node that hosts the control plane portion of protocols such as RRC and PDCP for an en-gNB or gNB-CU of a gNB. The gNB-CU-CP terminates the E1 interface with the gNB-CU-UP and the F1-C interface with the gNB-DU.

[0602] The gNB-CU user plane (gNB-CU-UP) includes, for example, a logical node that hosts, for example, the user plane portion of the PDCP protocol for the gNB-CU of the en-gNB, and the user plane portions of the PDCP protocol and the SDAP protocol for the gNB-CU of the gNB. The gNB-CU-UP terminates the E1 interface with the gNB-CU-CP and the F1-U interface with the gNB-DU, for example, according to section 3.1 of 3GPP TS 38.401 V16.6.0 (2021-07), incorporated by reference.

[0603] There can be different functional splits between central and distributed units, called options for example:

[0604] Option 1 (Class 1A Split):

[0605] - The functional split in this option is similar to the 1A architecture in DC. RRC is located in the central unit. PDCP, RLC, MAC, physical layer, and RF are located in the distributed unit.

[0606] Option 2 (Class 3C Split):

[0607] - The functional split in this option is similar to the 3C architecture in DC. RRC and PDCP are located in the central unit. RLC, MAC, physical layer, and RF are located in the distributed unit.

[0608] Option 3 (split within RLC):

[0609] - Low RLC (part of the RLC functionality), MAC, physical layer, and RF are located in the distributed unit. PDCP and High RLC (another part of the RLC functionality) are located in the central unit.

[0610] Option 4 (RLC-MAC Split):

[0611] -MAC, physical layer and RF are located in the distributed unit. PDCP and RLC are located in the central unit.

[0612] Otherwise, for example, according to 3GPP TR 38.801 V14.0.0 incorporated by reference

[0613] (2017-03) Section 11.

[0614] The gNB supports different protocol layers, such as Layer 1 (L1) - the physical layer.

[0615] NR's Layer 2 (L2) is split into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), where for example:

[0616] -The physical layer provides transport channels to the MAC sublayer;

[0617] -The MAC sublayer provides logical channels to the RLC sublayer;

[0618] -The RLC sublayer provides RLC channels to the PDCP sublayer;

[0619] -The PDCP sublayer provides radio bearers to the SDAP sublayer;

[0620] -SDAP sublayer provides QoS flow to 5GC;

[0621] -Comp. refers to header compression and Segm. refers to segmentation;

[0622] -Control channels include (BCCH, PCCH).

[0623] Layer 3 (L3) includes, for example, Radio Resource Control (RRC), e.g., according to 3GPP TS 38.300 V16.6.0 (2021-06) section 6, incorporated by reference.

[0624] A RAN (Radio Access Network) node or network node (such as a gNB, base station, gNB CU or gNB DU or part thereof) can be implemented using, for example, a device having at least one processor and / or at least one memory (with computer-readable instructions (computer program)), which is configured to support and / or provide and / or process CU and / or DU related functions and / or features, and / or at least one protocol (sub) layer of the RAN (Radio Access Network), such as Layer 2 and / or Layer 3.

[0625] The gNB CU and gNB DU parts can be, for example, collocated or physically separated. The gNB DU can be even further split into two parts, for example, one part including processing equipment and the other part including antennas. The central unit (CU) can also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN or parts thereof. The distributed unit (DU) can also be referred to as RRH / RRU / RE / RU or parts thereof. Hereinafter, in various example embodiments of the present disclosure, the CU-CP (or more generally, CU) can also be referred to as a (first) network node that supports at least one of the central unit control plane functions or layer 3 protocols of the radio access network; and similarly, the DU can be referred to as a (second) network node that supports at least one of the distributed unit functions or layer 2 protocols of the radio access network.

[0626] A gNB-DU supports one or more cells and can therefore serve as a serving cell for, for example, a user equipment (UE).

[0627] The term 'comprising' is used in this document in an inclusive, rather than exclusive, sense. That is, any reference to X including Y indicates that X may include only one Y or may include more than one Y. If the exclusive meaning of 'comprising' is intended, this will be made clear in the context by reference to "including only one" or by the use of "consisting of."

[0628] Throughout this specification, the terms "connected," "coupled," and "in communication with" and their derivatives refer to being operationally connected / coupled / in communication with one another. It should be understood that any number or combination of intermediary components (including no intermediary components) may be present, i.e., to provide direct or indirect connections / couplings / in communication with one another. Any such intermediary components may include hardware and / or software components.

[0629] As used herein, the term "determine" / "determining" (and grammatical variations thereof) may include at least: calculating, computing, processing, deriving, measuring, investigating, identifying, searching (e.g., searching in a table, a database, or another data structure), confirming, etc. Furthermore, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), obtaining, etc. Furthermore, "determine" / "determining" may include resolving, selecting, choosing, establishing, etc.

[0630] In this specification, reference is made to various examples. The description of features or functionality associated with an example indicates that those features or functionality are present in that example. The use of the term 'example' or 'for example' or 'may' or 'could' in the text indicates (whether or not explicitly stated) that such features or functionality are present in at least the example being described, whether or not described as an example, and that they may, but need not, be present in some or all other examples. Thus, 'example' or 'for example' or 'may' or 'could' refers to a particular instance within a class of examples. Attributes of an instance may be attributes of only that instance or attributes of a class or a subclass of a class that includes some but not all instances of the class. Thus, it is implicitly disclosed that features described with reference to one example but not with reference to another example may, where possible, be used as part of a working combination in that other example, but need not necessarily be used in that other example.

[0631] Although the examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims.

[0632] Features described in the preceding description may be used in other combinations than the combinations explicitly described above.

[0633] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0634] Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not.

[0635] As used in this document, the terms 'a,' 'an,' or 'the' are inclusive, not exclusive. That is, any reference to X that includes a / an / the Y indicates that X may include only one Y or may include more than one Y, unless the context clearly indicates otherwise. If the use of 'a,' 'an,' or 'the' in an exclusive sense is intended, this will be made clear in the context. In some cases, 'at least one' or 'one or more' may be used to emphasize an inclusive meaning, but the absence of these terms should not be construed as inferring any exclusive meaning.

[0636] The presence of a feature (or combination of features) in a claim is a reference to that feature (or combination of features) itself, as well as to features that achieve substantially the same technical effect (equivalent features). Equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. Equivalent features include, for example, features that perform substantially the same function in substantially the same way to achieve substantially the same result.

[0637] In this specification, reference is made to various examples using adjectives or adjective phrases to describe features of the examples. Such description of a characteristic associated with an example indicates that the characteristic exists in some examples exactly as described and in other examples substantially as described.

[0638] The above description describes some examples of the present disclosure, however, those skilled in the art will be aware of possible alternative structures and method features that provide equivalent functionality to the specific examples of such structures and features described above, and for the sake of brevity and clarity, such alternative structures and features have been omitted from the above description. Nevertheless, the above description should be understood to implicitly include reference to such alternative structures and method features that provide equivalent functionality, unless such alternative structures or method features are explicitly excluded in the above description of examples of the present disclosure.

[0639] While efforts have been made in the foregoing description to draw attention to those features regarded as of significance, it will be understood that the applicant may seek protection by way of claims for any patentable feature or combination of features mentioned above and / or shown in the drawings, whether or not emphasized.

Claims

1. A user equipment (UE), comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the at least one processor, cause the UE to at least perform: receiving downlink signaling providing a first data radio bearer (DRB) configuration for a cell and a second data radio bearer (DRB) configuration for the cell; storing the first data radio bearer configuration for performing data transmission via the cell using the first data radio bearer, and storing the second data radio bearer configuration for performing data transmission via the cell using the second data radio bearer; Receive trigger; as well as In response to receiving the trigger, If the trigger indicates use of the first data radio bearer configuration, performing data transmission between the user equipment and the cell using the first data radio bearer configuration, and If the trigger indicates use of the second data radio bearer configuration, data transmission is performed between the user equipment and the cell using the second data radio bearer configuration.

2. The apparatus of claim 1 , wherein the control circuitry is configured to switch a data transmission session between transmission using the first data radio bearer configuration or transmission using the second data radio bearer configuration based on the trigger, or Wherein the control circuitry is configured to open or close a data transfer session based on the trigger.

3. The apparatus of claim 1 or 2, wherein the trigger is received as a medium access control (MAC) message.

4. The apparatus according to claim 1 , wherein the trigger indicates that a mapping between data radio bearers and data transmission sessions for the cell is to be used in the received first configuration or the second configuration for the cell.

5. The apparatus according to any one of the preceding claims, wherein the first data radio bearer configuration or the second data radio bearer configuration comprises: At least one mapping between available data transmission sessions to provide data for transmission and available data radio bearers to provide a transmission channel for the data.

6. The apparatus of claim 5, wherein the at least one mapping maps a data transfer session to a subset of a set of a plurality of preconfigured data radio bearers, wherein the subset is indicated by the trigger.

7. The apparatus of claim 6, wherein the data transmission session is a pre-existing data transmission session 8. A device according to any one of the preceding claims, wherein The first data radio bearer configuration and the second data radio bearer configuration configure data radio bearers for a first data transmission session and a second data transmission session, wherein If the trigger indicates use of the first data radio bearer configuration, performing data transmission with a user equipment via the cell using the first data radio bearer configuration comprises: performing the second data transfer session using the first data radio bearer configuration, and If the trigger indicates use of the second data radio bearer configuration, performing data transmission with the user equipment via the cell using the second data radio bearer configuration comprises: performing the second data transmission session using the second data radio bearer configuration 9. The device according to any one of the preceding claims, wherein There are states in which the data transfer session is mapped to a subset of the set of a plurality of preconfigured data radio bearers, and states in which the data transfer session is not mapped to any preconfigured data radio bearer, wherein the states are indicated by the trigger.

10. The apparatus according to any of the preceding claims, wherein the first data radio bearer configuration and the second data radio bearer configuration are at least a first data transfer session, and optionally a second data transfer session configuration data radio bearers, in If the trigger indicates use of the first data radio bearer configuration, performing the second data transmission between the user equipment and the cell using the first data radio bearer configuration includes: performing the second data transmission session using the first data radio bearer configuration, Performing the second data transmission between the user equipment and the cell using the second data radio bearer configuration if the trigger indicates use of the second data radio bearer configuration includes performing the second data transmission session with the second data radio bearer configuration.

11. A method comprising: receiving downlink signaling providing a first data radio bearer (DRB) configuration for a cell and a second data radio bearer (DRB) configuration for the cell; storing the first data radio bearer configuration for performing data transmission via the cell using the first data radio bearer, and storing the second data radio bearer configuration for performing data transmission via the cell using the second data radio bearer; Receive trigger; If the trigger indicates use of the first data radio bearer configuration, performing data transmission between the user equipment and the cell using the first data radio bearer configuration, and If the trigger indicates use of the second data radio bearer configuration, data transmission is performed between the user equipment and the cell using the second data radio bearer configuration.

12. The method according to claim 11, wherein the execution of data transmission between the cell and the user equipment requires mapping between available data transmission sessions for providing the transmitted data and available data radio bearers for providing a transmission channel for the data.

13. The method according to claim 12 , wherein at a time when data transmission between the user equipment and the cell is triggered using the data radio bearer for the cell as a result of the received trigger, there is a mapping for the cell between the data radio bearer for the cell and a data transmission session.

14. The method according to any one of claims 11 to 13, wherein performing data transmission between the user equipment and the cell requires: - available data transfer sessions to provide data for transmission, - available data radio bearers, used to provide a transport channel for data, in At the time of triggering, a data radio bearer for the cell is available for the cell, and At the time of the downlink signaling, the data radio bearer for the cell is not available for the cell, and / or in At said time of triggering, a data transfer session is available for said cell, and At the time of the signaling, the data transfer session is not available for the cell.

15. The method according to claim 14, wherein At the time of triggering, a data transfer session is available for the cell and the data radio bearer of the cell is available for the cell; and At the time of said downlink signaling, The data transmission session is available for the cell, whereas the data radio bearer is not available for the cell, or The data transmission session is unavailable for the cell, while the data radio bearer is available for the cell.

16. A computer program for a user equipment, comprising instructions which, when executed on a computer, perform: conditionally performing data transmission between the user equipment and a cell, wherein if the trigger indicates use of a previously received and stored first data radio bearer configuration, causing data transmission to be performed between the user equipment and the cell using the first data radio bearer configuration, and If the trigger indicates use of a previously received and stored second data radio bearer configuration, causing data transmission to be performed between the user equipment and the cell using the second data radio bearer configuration.

17. An apparatus for a radio access network, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: causing transmission of downlink signaling to a user equipment, the downlink signaling providing a first data radio bearer configuration for a cell and a second data radio bearer configuration for the cell; causing transmission of a trigger to the user equipment, the trigger being configured to indicate use of the first data radio bearer configuration to enable data transmission between the user equipment and the cell using the first data radio bearer, or The method is configured to indicate use of the second data radio bearer configuration to enable data transmission between the user equipment and the cell using the second data radio bearer.

18. The apparatus of claim 17 , configured to receive and use a configuration of the first data radio bearer configuration for the cell and a configuration of the second data radio bearer configuration for the cell to enable providing the downlink signaling of the first data radio bearer configuration for the cell and the second data radio bearer configuration for the cell.

19. The apparatus according to any one of claims 17 to 18, configured to receive and use at least one decision criterion for causing the transmission of the trigger to the user equipment and / or setting a mapping parameter in the trigger.

20. The apparatus of claim 19, wherein the decision criteria specifies at least one of the following: d. Availability of data radio bearers at the current cell, e. Availability of data radio bearers at future cells, f. New data transfer session 21. An apparatus according to any one of claims 17 to 20, configured to receive and use a report, the report comprising: Information of the decision criteria for causing the transmission of the trigger to the user equipment and / or setting a mapping parameter in the trigger.

22. The apparatus of claim 21, configured to receive and use a report, the report comprising: Information indicating availability of a data radio bearer at the cell is used for enabling transmission of the trigger to the user equipment and / or setting the decision criterion for a mapping parameter in the trigger.

23. The apparatus according to any one of claims 21 or 22, wherein the report is a periodic report or an event-based report.

24. The apparatus according to any one of claims 21 to 23, wherein the report indicates a lack of resources or the presence of resources for one or more data radio bearer configurations.

25. The apparatus of any one of claims 17 to 24, wherein the trigger is a medium access control (MAC) layer message.

26. The apparatus according to any one of claims 25, wherein the apparatus determines cell switching according to a Low Layer Triggered Mobility procedure (LTM).

27. The apparatus according to any one of claims 17 to 25, configured as a distributed unit of a centralized unit distributed unit network architecture.

28. The apparatus of claim 27, wherein the apparatus is configured to receive and process an indication of a newly established data radio bearer from the centralized unit.

29. The apparatus according to claim 27 or 28, wherein the centralized unit determines cell switching according to a Low Layer Triggered Mobility (LTM) procedure and notifies the apparatus.

30. The apparatus according to any one of claims 27 to 29, configured to receive and process an indication from the centralized unit, the indication indicating that the first data radio bearer configuration and the second data radio bearer configuration have been sent to the user equipment.

31. An apparatus according to any one of claims 27 to 29, configured to receive and process decision criteria for causing the transmission of the trigger to the user equipment.

32. The apparatus of claim 31 , wherein the decision criteria specifies at least one of the following: d. Availability of data radio bearers at the current cell, e. the availability of data radio bearers at the cell, f. New data transfer session 33. The apparatus according to any one of claims 21 or 22, wherein the report is a periodic report, or an event-based report, and / or The report indicates a lack of resources or an existence of resources for one or more data radio bearer configurations.

34. A user equipment (UE) configured to connect to a first cell of a first network node supporting a distributed unit (DU) functionality and / or layer 2 protocol processing of a radio access network (RAN), the UE comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least: establishing a connection with the first cell, sending data to said first cell using at least a first data radio bearer, performing L3 measurements on at least one candidate target cell of a plurality of candidate target cells to potentially hand over to, sending an L3 measurement report relating to the performed measurements to a second network node, the second network node supporting a Central Unit (CU) functionality and / or a layer 3 protocol processing of the radio access network RAN and being connected to the first node, receiving an L3 configuration message, the L3 configuration message including configuration information related to at least one candidate target cell among the plurality of candidate target cells for L1L2 triggered mobility LTM, wherein the configuration information includes a pre-configuration for potentially using a second data radio bearer different from the first data radio bearer to send data to the target cell to be handed over; and receiving an L2 message, the L2 message including a trigger for handover from the first cell to a target cell, and an implicit or explicit indication indicating whether the preconfigured data radio bearer is to be used to send data to the target cell and / or whether a currently used first data radio bearer is to be retained and used to send data to the target cell, Establishing a connection with the indicated target cell, Data is sent to the target cell using at least the indicated data radio bearer.

35. The user equipment (UE) according to claim 34, wherein the indicated target cell is a cell of a third network node supporting a distributed unit (DU) function and / or layer 2 protocol processing of the radio access network (RAN).

36. The user equipment (UE) according to claim 35, wherein the third network node is connected to the second network node.

37. The user equipment (UE) according to claim 34, wherein the L3 configuration message is an RRCConfiguration message or an RRCReconfiguration message.

38. The user equipment (UE) according to claim 34, wherein the L2 message is a MAC CE message.

39. The user equipment (UE) according to claim 34, wherein the UE is further configured to: sending data to the first cell using a third data radio bearer, and The configuration information includes: and maintaining a configuration for sending data to the target cell to be handed over using the third data radio bearer.

40. The user equipment (UE) according to claim 34, wherein The implicit or explicit indication of whether the preconfigured data radio bearer is to be used is received as part of the received L2 message.

41. The user equipment (UE) according to claim 34, wherein The implicit or explicit indication of whether the preconfigured data radio bearer is to be used is indicated in at least one of the following ways: - there is no indication that the preconfigured data radio bearer is to be used, - a flag or specific instruction to use the preconfigured data radio bearer, - a flag or a specific instruction for reserving the first data radio bearer, - a flag or specific instruction to use the preconfigured data radio bearer and reserve the first data radio bearer.

42. The user equipment (UE) according to claim 34, wherein The configuration information also includes: Instructions for sending data to the target cell to be handed over using the preconfigured second data radio bearer instead of the first data radio bearer if no further instructions for reserving the first data radio bearer for sending data to the target cell to be handed over are received.

43. The user equipment (UE) according to claim 34, wherein The configuration information includes: A preconfiguration for potentially using a second data radio bearer having a specific QoS level, and the implicit or explicit indication specifies: using the preconfigured data radio bearer with its specific QoS level to send data to the target cell, and retaining the first data radio bearer and its assigned QoS for sending data to the target cell.

44. The user equipment (UE) according to claim 34, wherein The specific QoS level and the allocated QoS level are different.

45. The user equipment (UE) according to claim 34, wherein The implicit or explicit indication indicates that data is sent to the target cell using the preconfigured data radio bearer in a first PDU session and the first data radio bearer is reserved, and is a QoS mapping for a second PDU session, wherein the first PDU session and the second PDU session are different sessions.

Images