Method and apparatus for signaling radio link failure

Abstract

A device includes: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least: operate the device in a dual connectivity mode, wherein the device communicates with a primary cell group including a primary cell and at least one secondary cell, and the device communicates with a secondary cell group including a primary cell and at least one secondary cell; detect a radio link failure between the device and a primary cell of the secondary cell group; and provide information based on the radio link failure to the primary cell of the primary cell group, the information being that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

Description

Technical Field

[0001] The present disclosure relates to an apparatus, method and computer program, and in particular, but not exclusively, to an apparatus, method and computer program for signaling radio link failure, in particular when primary cell group fast recovery is configured. Background Art

[0002] A communication system can be considered as a facility that enables communication sessions between two or more entities (such as communication devices, base stations / access points, and / or other nodes) by providing carrier waves between the various entities involved in the communication path. For example, a communication system can be provided by a communication network and one or more compatible communication devices.

[0003] Access to a communication system can be via an appropriate communication device or terminal. A communication device is provided with appropriate signal reception and transmission means to enable communications, such as access to a communication network or direct communication with other communication devices. A communication device can access a carrier provided by a station or access point and transmit and / or receive communications on that carrier.

[0004] Communication systems and associated devices typically operate according to a given standard or specification that specifies what the various entities associated with the system are allowed to do and how it should be implemented. Communication protocols and / or parameters for connections are also typically defined. One example of a communication system is UTRAN (3G radio). Another example of an architecture is called Long Term Evolution (LTE) or Universal Mobile Telecommunications System (UMTS) radio access technology. Another example communication system is the so-called 5G radio or New Radio (NR) access technology. Summary of the Invention

[0005] According to one aspect, a device is provided, comprising: at least one processor; and at least one memory comprising computer program code; the at least one memory and the computer program code being configured to, together with the at least one processor, cause the device to at least: operate the device in a dual connectivity mode, wherein the device communicates with a primary cell group comprising a primary cell and at least one secondary cell, and the device communicates with a secondary cell group comprising a primary cell and at least one secondary cell; detect a radio link failure between the device and a primary cell of the secondary cell group; and provide information based on the radio link failure to the primary cell of the primary cell group, the information being that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0006] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to transmit at least information configured by the primary cell of the secondary cell group via its radio link or a radio link of a primary cell of the primary cell group.

[0007] The information may also be configured to inform the primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration.

[0008] The information configured to notify a primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration may be a bitmap configured to indicate at least one candidate cell within a measured cell list.

[0009] The information may also be configured to notify the primary cell of the primary cell group of the conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of the primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

[0010] The information may also be configured to notify the primary cell of the primary cell group that the signal measurements of the primary cell of the secondary cell group and at least one candidate cell from the secondary cell group may be differences between the primary cell of the secondary cell group and the at least one candidate cell, and corresponding conditional change execution conditions of the conditional cell change associated with the cell.

[0011] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to at least: receive a radio resource control message from a primary cell of the primary cell group, the radio resource control message including a cell identity of a ready cell from the secondary cell group to be changed to; and perform a cell change from the primary cell of the secondary cell group to the ready cell from the secondary cell group based on the cell identity.

[0012] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to at least: receive a radio resource control reconfiguration message from a primary cell of the primary cell group, the radio resource control reconfiguration message including cell identities of other cells except the ready cell to be changed to from the secondary cell group; and perform a cell change from the primary cell of the secondary cell group to a not-ready cell from the secondary cell group based on the cell identities.

[0013] The apparatus may be user equipment.

[0014] According to a second aspect, a device is provided, comprising: at least one processor; and at least one memory comprising computer program code; the at least one memory and the computer program code being configured to, together with the at least one processor, cause the device to at least: communicate with at least one other device, wherein the other device is configured to operate in dual connectivity mode, communicate with a primary cell group, and communicate with a secondary cell group, the primary cell group comprising the device as a primary cell, and at least one secondary cell, the secondary cell group comprising the primary cell and at least one secondary cell; and receive, from the at least one other device, information based on a radio link failure between the at least one other device and a primary cell of the secondary cell group, the information being information that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0015] The information may also be configured to inform the apparatus of an identity value associated with at least one candidate cell from the secondary cell group for which the at least one further apparatus has a valid conditional change configuration.

[0016] The information configured to inform the apparatus of an identity value associated with at least one candidate cell from the secondary cell group for which at least one further apparatus has a valid conditional change configuration may be a bitmap configured to indicate the at least one candidate cell within a measured cell list.

[0017] The information may also be configured to inform the apparatus of a conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of a primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

[0018] The information may also be configured to inform the apparatus that signal measurements of the primary cell of the secondary cell group and at least one candidate cell from the secondary cell group are differences between the primary cell of the secondary cell group and the at least one candidate cell, and corresponding conditional change execution conditions of the conditional cell change associated with the cell.

[0019] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to at least: generate a radio resource control message based on the information, the radio resource control message including a cell identity of a ready cell from the secondary cell group to be changed to; and provide the radio resource control message to at least one further apparatus, such that the at least one further apparatus is configured to perform a cell change from a primary cell of the secondary cell group to a ready cell from the secondary cell group based on the cell identity.

[0020] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to at least: generate a radio resource control reconfiguration message based on the information, the radio resource control reconfiguration message including cell identities of other cells other than the ready cell to be changed to from the secondary cell group; and provide the radio resource control message to at least one further apparatus, so that the at least one further apparatus is configured to perform a cell change from a primary cell of the secondary cell group to a not ready cell from the secondary cell group based on the cell identity.

[0021] The device may be a master node.

[0022] According to a third aspect, a device is provided, comprising: at least one processor; and at least one memory comprising computer program code; the at least one memory and the computer program code being configured to, together with the at least one processor, cause the device to at least: communicate with at least one other device, wherein the other device is configured to operate in a dual connectivity mode, communicate with a primary cell group, and communicate with a secondary cell group, the primary cell group comprising a primary cell, and at least one secondary cell, the secondary cell group comprising the primary cell, and the device as a secondary cell; and receive information on a cell change from the primary cell of the secondary cell group from the at least one other device.

[0023] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to at least: receive a message from a primary cell of the primary cell group, the message including information based on a radio link failure between the primary cell of the secondary cell group and at least one further apparatus while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0024] According to a fourth aspect, a method for a device is provided, the method comprising: operating the device in a dual connectivity mode, wherein the device communicates with a primary cell group including a primary cell and at least one secondary cell, and the device communicates with a secondary cell group including a primary cell and at least one secondary cell; detecting a radio link failure between the device and a primary cell of the secondary cell group; and providing information based on the radio link failure to the primary cell of the primary cell group, the information being information that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0025] The method may further include transmitting information configured by the primary cell of the secondary cell group via its radio link or a radio link of the primary cell of the primary cell group.

[0026] The information may also be configured to inform the primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration.

[0027] The information configured to notify a primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration may be a bitmap configured to indicate at least one candidate cell within a measured cell list.

[0028] The information may also be configured to notify the primary cell of the primary cell group of the conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of the primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

[0029] The information may also be configured to notify the primary cell of the primary cell group that the signal measurements of the primary cell of the secondary cell group and at least one candidate cell from the secondary cell group may be differences between the primary cell of the secondary cell group and the at least one candidate cell, and corresponding conditional change execution conditions of the conditional cell change associated with the cell.

[0030] The method may include receiving a radio resource control message from a primary cell of the primary cell group, the radio resource control message including a cell identity of a ready cell from the secondary cell group to be changed to; and performing a cell change from the primary cell of the secondary cell group to the ready cell from the secondary cell group based on the cell identity.

[0031] The method may include: receiving a radio resource control reconfiguration message from a primary cell of a primary cell group, the radio resource control reconfiguration message including cell identities of other cells except a ready cell to be changed to from a secondary cell group; and performing a cell change from the primary cell of the secondary cell group to a not-ready cell from the secondary cell group based on the cell identities.

[0032] The apparatus may be user equipment.

[0033] According to a fifth aspect, a method for a device is provided, the method comprising: communicating with at least one other device, wherein the other device is configured to operate in a dual connectivity mode, communicating with a primary cell group, and communicating with a secondary cell group, the primary cell group including the device as a primary cell, and at least one secondary cell, the secondary cell group including the primary cell and at least one secondary cell; receiving, from the at least one other device, information based on a radio link failure between the at least one other device and the primary cell of the secondary cell group, the information being that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0034] The information may also be configured to inform the apparatus of an identity value associated with at least one candidate cell from the secondary cell group for which the at least one further apparatus has a valid conditional change configuration.

[0035] The information configured to inform the apparatus of an identity value associated with at least one candidate cell from the secondary cell group for which at least one further apparatus has a valid conditional change configuration may be a bitmap configured to indicate the at least one candidate cell within a measured cell list.

[0036] The information may also be configured to inform the apparatus of a conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of a primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

[0037] The information may also be configured to inform the apparatus that signal measurements of the primary cell of the secondary cell group and at least one candidate cell from the secondary cell group are differences between the primary cell of the secondary cell group and the at least one candidate cell, and corresponding conditional change execution conditions of the conditional cell change associated with the cell.

[0038] The method may include: generating a radio resource control message based on the information, the radio resource control message including a cell identity of a ready cell from the secondary cell group to which the change is to be made; and providing the radio resource control message to at least one further apparatus, so that the at least one further apparatus is configured to perform a cell change from a primary cell of the secondary cell group to a ready cell from the secondary cell group based on the cell identity.

[0039] The method may include: generating a radio resource control reconfiguration message based on the information, the radio resource control reconfiguration message including cell identities of other cells except the ready cell to be changed to from the secondary cell group; and providing the radio resource control message to at least one further apparatus, so that the at least one further apparatus is configured to perform a cell change from a primary cell of the secondary cell group to a not ready cell from the secondary cell group based on the cell identities.

[0040] The device may be a master node.

[0041] According to a sixth aspect, a method for a device is provided, the method comprising: communicating with at least one other device, wherein the other device is configured to operate in a dual connectivity mode, communicating with a primary cell group including a primary cell and at least one secondary cell, and communicating with a secondary cell group including the primary cell and the device as a secondary cell; and receiving, from at least one other device, information on a cell change from the primary cell of the secondary cell group.

[0042] The method may include receiving a message from a primary cell of the primary cell group, the message including information based on a radio link failure between the primary cell of the secondary cell group and at least one further device while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0043] According to a seventh aspect, a device is provided, comprising a component configured to: operate the device in a dual connectivity mode, wherein the device communicates with a primary cell group including a primary cell and at least one secondary cell, and the device communicates with a secondary cell group including a primary cell and at least one secondary cell; detect a radio link failure between the device and a primary cell of the secondary cell group; and provide information based on the radio link failure to the primary cell of the primary cell group, wherein the radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0044] The component may be configured to transmit information configured by the primary cell of the secondary cell group via its radio link or a radio link of a primary cell of the primary cell group.

[0045] The information may also be configured to inform the primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration.

[0046] The information configured to notify a primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration may be a bitmap configured to indicate at least one candidate cell within a measured cell list.

[0047] The information may also be configured to notify the primary cell of the primary cell group of the conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of the primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

[0048] The information may also be configured to notify the primary cell of the primary cell group that the signal measurements of the primary cell of the secondary cell group and at least one candidate cell from the secondary cell group may be differences between the primary cell of the secondary cell group and the at least one candidate cell, and corresponding conditional change execution conditions of the conditional cell change associated with the cell.

[0049] The component may be configured to: receive a radio resource control message from a primary cell of the primary cell group, the radio resource control message including a cell identity of a ready cell from the secondary cell group to be changed to; and perform a cell change from the primary cell of the secondary cell group to the ready cell from the secondary cell group based on the cell identity.

[0050] The component may be configured to: receive a radio resource control reconfiguration message from a primary cell of the primary cell group, the radio resource control reconfiguration message including cell identities of other cells except the ready cell to be changed to from the secondary cell group; and perform a cell change from the primary cell of the secondary cell group to the not-ready cell from the secondary cell group based on the cell identities.

[0051] The apparatus may be user equipment.

[0052] According to an eighth aspect, a device is provided, comprising a component configured to: communicate with at least one other device, wherein the other device is configured to operate in a dual connectivity mode, communicate with a primary cell group, and communicate with a secondary cell group, the primary cell group including the device as a primary cell, and at least one secondary cell, the secondary cell group including the primary cell and at least one secondary cell; and receive, from the at least one other device, information based on a radio link failure between the at least one other device and the primary cell of the secondary cell group, the information being that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0053] The information may also be configured to inform the apparatus of an identity value associated with at least one candidate cell from the secondary cell group for which the at least one further apparatus has a valid conditional change configuration.

[0054] The information configured to inform the apparatus of an identity value associated with at least one candidate cell from the secondary cell group for which at least one further apparatus has a valid conditional change configuration may be a bitmap configured to indicate the at least one candidate cell within a measured cell list.

[0055] The information may also be configured to inform the apparatus of a conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of a primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

[0056] The information may also be configured to inform the apparatus that signal measurements of the primary cell of the secondary cell group and at least one candidate cell from the secondary cell group are differences between the primary cell of the secondary cell group and the at least one candidate cell, and corresponding conditional change execution conditions of the conditional cell change associated with the cell.

[0057] The component may be configured to: generate a radio resource control message based on the information, the radio resource control message including a cell identity of the ready cell from the secondary cell group to which the change is to be made; and provide the radio resource control message to at least one further apparatus, such that the at least one further apparatus is configured to perform a cell change from the primary cell of the secondary cell group to the ready cell from the secondary cell group based on the cell identity.

[0058] The component may be configured to: generate a radio resource control reconfiguration message based on the information, the radio resource control reconfiguration message including cell identities of other cells except the ready cell to be changed to from the secondary cell group; and provide the radio resource control message to at least one further apparatus, so that the at least one further apparatus is configured to perform a cell change from the primary cell of the secondary cell group to the not ready cell from the secondary cell group based on the cell identities.

[0059] The device may be a master node.

[0060] According to a ninth aspect, a device is provided, comprising a component configured to: communicate with at least one other device, wherein the other device is configured to operate in a dual connectivity mode, communicate with a primary cell group including a primary cell and at least one secondary cell, and communicate with a secondary cell group including a primary cell and the device as a secondary cell; and receive information on a cell change from the primary cell of the secondary cell group from at least one other device.

[0061] The component may be configured to receive a message from a primary cell of the primary cell group, the message including information based on a radio link failure between the primary cell of the secondary cell group and at least one further apparatus while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0062] According to the tenth aspect, a non-transitory computer-readable storage medium comprising computer-readable instructions is provided, which, when executed by at least one processor, causes an apparatus to: operate the apparatus in a dual-connectivity mode, wherein the apparatus communicates with a primary cell group comprising a primary cell and at least one secondary cell, and the apparatus communicates with a secondary cell group comprising a primary cell and at least one secondary cell; detect a radio link failure between the apparatus and a primary cell of the secondary cell group; and provide information based on the radio link failure to the primary cell of the primary cell group, the information being that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0063] According to an eleventh aspect, a non-transitory computer-readable storage medium comprising computer-readable instructions is provided, which, when executed by at least one processor, causes a device to: communicate with at least one other device, wherein the other device is configured to operate in a dual-connectivity mode, communicate with a primary cell group, and communicate with a secondary cell group, the primary cell group including the device as a primary cell, and at least one secondary cell, the secondary cell group including the primary cell and at least one secondary cell; and receive, from at least one other device, information based on a radio link failure between the at least one other device and the primary cell of the secondary cell group, the information being information that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0064] According to the twelfth aspect, a non-transitory computer-readable storage medium comprising computer-readable instructions is provided, which, when executed by at least one processor, causes a device to: communicate with at least one other device, wherein the other device is configured to operate in a dual-connectivity mode, communicate with a primary cell group comprising a primary cell and at least one secondary cell, and communicate with a secondary cell group comprising a primary cell and the device as a secondary cell; and receive information on a cell change from the primary cell of the secondary cell group from at least one other device.

[0065] According to a thirteenth aspect, a computer program is provided, comprising instructions for causing an apparatus to perform at least the following operations: operate the apparatus in a dual connectivity mode, wherein the apparatus communicates with a primary cell group comprising a primary cell and at least one secondary cell, and the apparatus communicates with a secondary cell group comprising a primary cell and at least one secondary cell; detect a radio link failure between the apparatus and a primary cell of the secondary cell group; and provide information based on the radio link failure to the primary cell of the primary cell group, the information being information that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0066] According to the fourteenth aspect, a computer program is provided, which includes instructions for causing a device to perform at least the following operations: communicate with at least one other device, wherein the other device is configured to operate in dual connectivity mode, communicate with a primary cell group, and communicate with a secondary cell group, the primary cell group includes the device as a primary cell, and at least one secondary cell, and the secondary cell group includes the primary cell and at least one secondary cell; from the at least one other device, receive information based on a radio link failure between the at least one other device and the primary cell of the secondary cell group, the information being that a radio link failure occurs on the secondary cell group while waiting for completion of a ready conditional cell change from the primary cell of the secondary cell group.

[0067] According to a fifteenth aspect, a computer program is provided, the computer program including instructions for causing an apparatus to at least perform the following operations: communicate with at least one other apparatus, wherein the other apparatus is configured to operate in dual connectivity mode, communicate with a primary cell group including a primary cell and at least one secondary cell, and communicate with a secondary cell group including the primary cell and the apparatus as a secondary cell; and receive, from the at least one other apparatus, information regarding a cell change from the primary cell of the secondary cell group. Many different aspects have been described above. It should be understood that additional aspects may be provided by combining any two or more of the aforementioned aspects.

[0068] Various other aspects are also described in the following detailed description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Some example embodiments will now be described in more detail, by way of example only, with reference to the following examples and accompanying drawings, in which:

[0070] Figure 1 A schematic diagram of a 5G system (5GS) is shown;

[0071] Figure 2 shows a schematic diagram of the control device;

[0072] Figure 3 shows a schematic diagram of a terminal;

[0073] Figure 4 A signaling diagram illustrating a procedure for performing conditional handover;

[0074] Figure 5 shows a signaling diagram of a procedure for performing a conditional PS cell change triggered by an SN;

[0075] Figure 6 A signaling diagram illustrating a procedure for secondary cell group failure messaging according to some embodiments; and

[0076] Figure 7 A schematic diagram illustrating a non-volatile storage medium storing instructions that, when executed by a processor, allow the processor to perform Figures 4 to 6 Any one or more of the steps of a process or method. DETAILED DESCRIPTION

[0077] In the following, certain embodiments are explained with reference to a mobile communication device capable of communicating via a wireless cellular system and a mobile communication system serving such a mobile communication device. Figure 1 、 Figure 2 and Figure 3Certain general principles of wireless communication systems, their access systems and mobile communication devices are briefly explained to help understand the technology underlying the described examples.

[0078] Figure 1 A schematic diagram of a 5G system (5GS) is shown. The 5GS may include a terminal or user equipment (UE), a 5G radio access network (5GRAN) or next-generation radio access network (NG-RAN), a 5G core network (5GC), one or more application functions (AFs), and one or more data networks (DNs).

[0079] The 5G-RAN may include one or more gNodeBs (GNBs) or one or more gNodeB (GNB) distributed unit functions connected to one or more gNodeB (GNB) centralized unit functions.

[0080] The 5GC may include the following entities: network slice selection function (NSSF); network exposure function; network repository function (NRF); policy control function (PCF); unified data management (UDM); application function (AF); authentication server function (AUSF); access and mobility management function (AMF); and session management function (SMF).

[0081] Figure 2 shows the control Figure 1 An example of a control device 200 for a 5GRAN or 5GC function is shown. The control device may include at least one random access memory (RAM) 211a, at least one read-only memory (ROM) 211b, at least one processor 212, 213, and an input / output interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute appropriate software code 215. The software code 215 may, for example, enable execution of one or more steps to implement one or more aspects of the present invention. The software code 215 may be stored in the ROM 211b. The control device 200 may be interconnected with another control device 200 that controls another function of the 5GRAN or 5GC. In some embodiments, each function of the 5GRAN or 5GC includes a control device 200. In alternative embodiments, two or more functions of the 5GRAN or 5GC may share a control device.

[0082] Figure 3 An example of a terminal 300 is shown, such as Figure 1The terminal 300 can be provided by any device capable of sending and receiving radio signals. Non-limiting examples include user equipment, mobile stations (MS) or mobile devices, such as mobile phones or so-called "smart phones", computers equipped with wireless interface cards or other wireless interface facilities (e.g., USB dongles), personal data assistants (PDAs) or tablets equipped with wireless communication capabilities, machine-type communication (MTC) devices, Internet of Things (IoT) type communication devices, or any combination thereof. The terminal 300 can, for example, provide data communication for bearer communication. The communication can be one or more of voice, electronic mail (email), text messaging, multimedia, data, machine data, etc.

[0083] The terminal 300 may receive signals over the air or radio interface 307 via suitable means for reception and may transmit signals via suitable means for transmission of radio signals. Figure 3 In FIG, the transceiver arrangement is schematically designated by block 306. The transceiver arrangement 306 may be provided, for example, by means of a radio part and an associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

[0084] Terminal 300 may be provided with at least one processor 301, at least one memory (ROM) 302a, at least one RAM 302b, and possibly other components 303 for use in its software and hardware-assisted execution of tasks designed to perform, including controlling access to and communication with access systems and other communication devices. The at least one processor 301 is coupled to RAM 302b and ROM 302a. The at least one processor 301 may be configured to execute appropriate software code 308. Software code 308 may, for example, enable execution of one or more aspects of the present invention. Software code 308 may be stored in ROM 302a.

[0085] The processor, storage device and other related control devices can be provided on an appropriate circuit board and / or in a chipset. This feature is indicated by reference numeral 304. The device may optionally have a user interface such as a keypad 305, a touch-sensitive screen or pad, a combination thereof, or the like. Optionally, one or more of a display, a speaker and a microphone may be provided, depending on the type of device.

[0086] One or more of the following aspects relate to mobility in a cellular / mobile communication network (such as an LTE network or a NR network).

[0087] Conditional Handover (CHO) is a feature specified in two separate work items (WI) in Release 16 for mobility enhancements for both LTE and NR. Conditional Handover is similar to Baseline Handover (BHO) and examples are Figure 4 shown.

[0088] In this example, a system is shown that includes a UE 401, a source node (SN) 403, a target node (TN) 405, other potential target nodes 407, a serving gateway / user plane function (S-GW / UPF) 409, and a mobility management entity / access and mobility management function (MME / AMF) 411. In this example, the user equipment 401 is configured to be handed over from the source node 403 to the target node 405 as part of a conditional handover.

[0089] The first operation is to trigger UE 401 to send a measurement report from UE 401 to source node 403 (based on an event), such as Figure 4 As shown in step 400 in .

[0090] The source node receiving the measurement report may then be configured to perform a conditional handover decision, wherein the source node hands over to another node (target node 405 or other potential target node(s) 407) based on the measurement report, e.g. Figure 4 As shown in step 402 in .

[0091] The source node is then configured to prepare one or more potential target nodes. This preparation may be achieved by transmitting a CHO request to the potential target node, such as Figure 4 As shown in steps 404 (CHO request to the target node) and 406 (CHO request to (multiple) other potential target nodes).

[0092] Receive messages and perform admission control, such as Figure 4 As shown in steps 408 (admission control within the target node) and 410 (admission control within (multiple) other potential target nodes).

[0093] In addition, the potential target node may be configured to transmit a confirmation message back to the source node 403, such as Figure 4 As shown in steps 412 (CHO request confirmation from the target node) and 414 (CHO request confirmation from (multiple) other potential target nodes).

[0094] After receiving the confirmation message, the source node 403 is then configured to generate and transmit a radio resource control (RRC) reconfiguration message or handover command to the UE 401, such as Figure 4 As shown in step 416 in .

[0095] In contrast to baseline handover (BHO), in which the UE will immediately access the target cell to complete the handover, for conditional handover (CHO), the UE 401 is configured to access the target cell only when an additional CHO execution condition expires. In other words, the HO preparation and execution phases are separated. The condition is configured, for example, by the source node in the HO command. Thus, for example, the UE is configured to evaluate the CHO condition, such as Figure 4 As shown in step 418 in .

[0096] While the CHO condition is being evaluated by the UE, data can still be exchanged between the UE 401 and the source node 403, e.g. Figure 4 As shown in step 420 in .

[0097] When the CHO condition of the target node is satisfied, the transmission / reception of user data between UE 401 and source node 403 is stopped, e.g. Figure 4 As shown in step 422 in .

[0098] In addition, the UE 401 is configured to transmit a physical random access channel (PRACH) preamble to the target node 405, such as Figure 4 As shown in step 424 in .

[0099] Then, a random access channel (RACH) response from the target node 405 is transmitted back to the UE 401, as shown in FIG. Figure 4 As shown in step 426 in .

[0100] Then, a radio resource control (RRC) reconfiguration complete message is transmitted from UE 401 to target node 405, such as Figure 4 As shown in step 428 in .

[0101] The target node 405 transmits a handover success message to the source node 403, such as Figure 4 As shown in step 430 in .

[0102] The source node 403 is then configured to stop data transmission / reception to / from the UE 401 and initiate a data forwarding operation for any received data, such as Figure 4 As shown in step 432 in .

[0103] Then, the sequence number (SN) state transfer message is forwarded from the source node 403 to the target node 405, such as Figure 4 As shown in step 434 in .

[0104] In addition, data forwarding is performed between the source node 403 and the target node 405, as shown in FIG. Figure 4 As shown in step 436 in .

[0105] The source node 403 further releases (multiple) other potential target nodes 407CHO ready, such as Figure 4 As shown in step 438 in .

[0106] Then, the path switching information is transmitted to the core network, such as Figure 4 As shown in step 440 in .

[0107] In this way, CHO enables sending the HO command as early as possible while the UE is still safe in the source cell, without jeopardizing access in the target cell and the stability of its radio link. That is, conditional handover provides mobility robustness.

[0108] CHO can also be extended for dual connectivity. In this case, there is a master cell group (MCG) including a primary cell (PCell) and one or more secondary cells (SCells), and a secondary cell group (SCG) including a primary cell (PSCell) and one or more secondary cells (PSCells).

[0109] In these cases, conditional handover functionality can be extended for the primary cell in the secondary group (PSCell) addition / change process associated with Multi-RAT Dual Connectivity (MR-DC) (non-standalone) scenarios. This can be defined as Conditional PSCell Change (CPC).

[0110] The CPC functions similarly to the CHO in a standalone architecture, such as Figure 4 As shown, the difference is that conditional execution applies to PSCell changes based on measurements of the secondary cell group (SCG). The radio link between the UE and the master node (MN) will be available during the execution of the conditional PSCell change, in which case the UE can use it for radio resource control (RRC) signaling, while in the case of CHO in a standalone architecture, the radio link between the UE and the network is completely interrupted from the start of the CHO execution to its completion. In addition, in the event of a failure scenario during the conditional PSCell change, the failure can be communicated to the master node in this case.

[0111] For example, about Figure 5 , an example conditional PSCell change (CPC) triggered by a secondary node using signaling radio bearer 3 (SRB3).

[0112] Thus, for example, UE 501 is configured to send a measurement report to the source primary cell in the secondary group (S-PSCell) 505, such as Figure 5 As shown in step 500 in .

[0113] Then, an RRCConnection reconfiguration message is sent back from the S-PSCell 505 to the UE 501, such as Figure 5 As shown in step 502 in .

[0114] The UE is then configured to evaluate CPC conditions such as Figure 5 As shown in step 504 in FIG. While the evaluation is being performed, data can be transmitted between the UE 501 and the primary node 503. Data transmission via the source secondary node is also possible in this case.

[0115] The CPC conditions of T-PSCell 507 are met, such as Figure 5 As shown in step 506 in .

[0116] When the CPC condition is met, a random access procedure (similar to Figure 4 The CHO conditions shown are met), such as Figure 5 As shown in step 508 in FIG. 5 , during this process, data transmission between the UE and the master node is still possible.

[0117] Then, when completed, UE 501 is configured to send an RRC connection reconfiguration complete message to T-PSCell 507, such as Figure 5 As shown in step 510 in .

[0118] In a basic PSCell change scenario initiated by a secondary node (SN) without involving a master node (MN), when the UE experiences a secondary group radio link failure (S-RLF) due to various reasons including timer failure (T310 expiration), the steps of the signaling procedure are as follows:

[0119] The UE suspends the secondary cell group (SCG) radio bearers and resets the secondary cell group medium access control (SCG-MAC);

[0120] The UE sends SCG failure information to the master node (MN) in a radio resource control (RRC) message via the MN radio link. The message includes the failure cause and the latest measurement report according to the measurement configuration per source node (SN); and

[0121] The MN may forward the SCG failure information to the SN via the SN modification request message to notify the failure scenario so that the SN may stop scheduling to the UE.

[0122] When a Master Node (MN) receives an SCG Failure Indication message from a UE, two actions are possible at the MN:

[0123] If the measurement results include a cell served by the same secondary node (SN), the master node (MN) may be configured to send an SN modification request to notify the SN of the SCG failure and allow the SN to take further actions to be signaled via the MN; and

[0124] If the measurement results include cells served by other secondary nodes (SNs), the master node (MN) can initiate the SN cell change procedure by triggering the SN add procedure without forwarding the SCG failure information to the source SN. Here, the MN has already decided to take action to handle the failure.

[0125] If an SCG failure occurs after the UE receives a conditional PSCell change (CPC) command from the SN, the SCG failure information indication needs to be improved so that the MN can take appropriate action on the failure taking into account the status of the conditional PSCell change and the ready cell information. Even in the case where the MN decides to trigger a PSCell change to a ready cell immediately, it needs to know this additional information.

[0126] As described above, the SCG failure information for providing information about SCG failure does not contain any indication about a ready PSCell. In other words, there is no information about a PSCell that was prepared by the SN without the participation of the MN and for which the UE has received a conditional PSCell change configuration.

[0127] For example, the SCG fault information message for NR SCG fault is as follows, and similar messages also exist for LTE SCG fault

[0128] SCGFailureInformation message

[0129]

[0130]

[0131]

[0132] The concept discussed in some embodiments is a signaling procedure for secondary cell radio link failure (S-RLF) reporting when a UE has a conditional primary cell (PSCell) change in a secondary group that has been configured by a secondary node (SN) without the involvement of a primary node (MN).

[0133] Therefore, in some embodiments, when an S-RLF is detected while there is a valid conditional PSCell change execution command pending, the UE sends an SCG Failure Indication message to the MN with the following changes:

[0134] The SCG Failure Indication message includes additional information to inform the MN that a conditional PSCell change is in progress. In some embodiments, this information may be indicated by a parameter / flag designated as the Conditional-PSCell-Change-pending parameter / flag. In other words, the UE has received the conditional PSCell change configuration but has not yet executed the change (e.g., an S-RLF has occurred while waiting for the PSCell change execution conditions to be met).

[0135] The SCG Failure Indication message can also be configured to indicate the cell identities of ready candidate PSCells for which the UE has a valid conditional change configuration. In some embodiments, this can be provided as a bitmap used to indicate ready cells within a measurement cell list. In some embodiments, the MN uses this information to decide whether to trigger an SN change to a not-ready cell or perform a PSCell change to a ready cell. Here, the MN can also use the signal strength difference between the ready and not-ready cells.

[0136] The UE may also be configured to include additional information regarding the execution conditions for the conditional PSCell change for each ready PSCell, along with measurements of the source PSCell and the ready PSCell. Alternatively, in some embodiments, and to simplify signaling, the SCG failure information may include the difference between the measurement results and the execution conditions for each measured cell. This information may be used by the MN to select a new PSCell among the ready cells.

[0137] In some embodiments, upon receiving this information, the MN may be configured to decide to send an RRC message containing the cell identity of the ready cell to which the immediate PSCell change should be triggered, and also notifying the SN that a conditional cell change execution is triggered.

[0138] Furthermore, in some embodiments, the MN may initiate a PSCell change to a non-ready target cell and send a new RRC reconfiguration message. In this case, the MN notifies the SN to cancel the conditional PSCell preparation as part of an inter-node message carrying SCG failure information.

[0139] In some embodiments, the modified SCG failure indication reporting may be controlled by the SN via RRC signaling, which is only applicable if the MN is not aware of the conditional cell change. Otherwise, the old SCG failure indication may continue.

[0140] about Figure 6 The message sequence of the modified SCG Failure Indication procedure triggered on S-RLF when a conditional PSCell change is pending is shown.

[0141] Thus, for example, UE 601, Master Node (MN) 603 and Secondary Node (SN) 605 are configured to operate in dual connectivity mode, such as Figure 6 As shown in step 600 in .

[0142] Then, as part of the conditional PSCell change of the target cell within the SN, the secondary node 605 is configured to transmit an RRC reconfiguration message to the UE, such as Figure 6 As shown in step 602 in .

[0143] At some point, the UE is configured to detect a secondary cell radio link failure (S-RLF), such as Figure 6 As shown in step 604 in .

[0144] This causes UE 601 to generate and transmit a Secondary Cell Group Failure message (SCG Failure message) to master node 603, such as Figure 6 As shown in step 608 in the SCG fault message. The SCG fault message includes this information (and is implemented as the following parameters):

[0145] Information indicating whether a conditional PSCell change is pending (CPC Pending). In other words, information indicating whether the UE has a valid conditional PSCell change configuration (or the execution condition has not been met) when S-RLF is detected;

[0146] Information indicating the cell identity (physical or global cell identity, PCI) of the PSCell that has been prepared for conditional PSCell change execution (ready cell information);

[0147] Information indicating the conditional PSCell execution condition for each ready target cell at the UE (CpscCondition); and

[0148] The measurement information (measurement results) of the source PSCell and the ready target PSCell may be included.

[0149] In some embodiments (and may be implemented as an alternative to the parameter Cpsc-condition), the message may also include information (Cpsc-condition-diff) including the difference between the measurement result and the execution condition for each measured cell. For example, the UE may be configured to indicate whether the condition has been fully met (at least temporarily, not necessarily for the duration of the trigger time). In some embodiments, if an A3 event is configured for a conditional PSCell change (the A3 event is that the target PSCell becomes better than the source PSCell offset), the UE may include in the message information indicating the difference between the measurement of the source PSCell and the target PSCell. In addition, in some embodiments, if an A5 event is configured for a conditional PSCell change (the A5 event is that the source PSCell becomes worse than threshold 1, while the target PSCell becomes better than threshold 2), the UE may be configured to include in the message information indicating the difference between the measurement of the target PSCell and threshold 2.

[0150] After receiving the SCG Failure Information message, the MN is configured to determine the target cell based on the ready cells in the measurement results. In some embodiments, the MN is configured to use the ready cell information and Cpsc-condition-diff to select the target cell. This is done by Figure 6 Step 608 in FIG.

[0151] In some embodiments, the master node is configured to generate and transmit an RRC reconfiguration message to the UE 601. The RRC reconfiguration message may include control to perform an immediate PSCell change of the ready cell identity, such as Figure 6 In some other embodiments, the RRC reconfiguration message may include control of performing PSCell change on the unready inter-SN target cell, such as Figure 6 As shown in step 612 in .

[0152] In some embodiments where the RRC reconfiguration message may include control of performing a PSCell change on an unready inter-SN target cell, the master node (MN) 603 is further configured to generate and transmit an SN modification request message to the secondary node (SN) 605, such as Figure 6 In some embodiments, the SN modification request message includes an SCG failure indicator and a flag or parameter indicating that a PSCell change is triggered.

[0153] In such an embodiment, when an S-RLF is detected, the fault message can provide the MN with additional information about the ready target PSCell. Additionally, using the extended information in the SCG fault report, the MN can react immediately by triggering the execution of a conditional PSCell change without having to wait for the SN to respond using the MN radio link, which saves additional signaling over the Xn interface and reduces latency when handling S-RLF. Furthermore, in some embodiments, due to the extended SCG fault information, the NW can release pre-reserved resources in candidate PSCells that are no longer under consideration (e.g., based on reported measurements of the ready PSCell).

[0154] Figure 7 A schematic diagram of non-volatile storage media 1300a (e.g., a computer disk (CD) or digital versatile disk (DVD)) and 1300b (e.g., a universal serial bus (USB) memory stick) storing instructions and / or parameters 1302 that, when executed by a processor, allow the processor to perform Figures 4 to 6 One or more of the steps of a process or method.

[0155] It should be noted that embodiments of the present invention may be implemented as a circuit system, implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. In example embodiments, the application logic, software, or instruction set is maintained on any of various conventional computer-readable media. In the context of this document, a "computer-readable medium" can be any medium or device that can contain, store, communicate, propagate, or transport instructions for use by or in connection with an instruction execution system, apparatus, or device (such as a computer or smartphone or user device).

[0156] As used in this application, the term "circuitry" refers to all of the following: (a) hardware circuit implementations alone (such as implementations in analog and / or digital circuitry alone), and (b) combinations of circuitry and software (and / or firmware), such as, as applicable: (i) a combination of processor(s), or (ii) portions of processor(s) / software (including digital signal processor(s), software, and memory(s) that work together to cause a device (such as a mobile phone or server) to perform various functions, and (c) circuitry, such as microprocessor(s) or portions of microprocessor(s) that require software or firmware to function, even if the software or firmware is not actually present. This definition of "circuitry" applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term "circuitry" would also encompass an implementation of only a processor(s) or portion(s) of a processor and its / their accompanying software and / or firmware. For example, the term "circuitry" would also encompass a baseband integrated circuit or applications processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, cellular network device, or other network device, if applicable to the particular claim element.

[0157] The described features, advantages and characteristics of the present invention may be combined in any suitable manner in one or more embodiments. Those skilled in the relevant art will recognize that the present invention may be practiced without one or more specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the present invention. Those of ordinary skill in the art will readily appreciate that the present invention as discussed above may be practiced with steps in a different order and / or with hardware elements in a configuration different from the disclosed configuration. Therefore, although the present invention has been described based on these preferred embodiments, it will be clear to those skilled in the art that certain modifications, variations and alternative structures will be clear while remaining within the spirit and scope of the present invention.

Claims

1. A device for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least: operating the apparatus in a dual connectivity mode, wherein the apparatus communicates with a primary cell group including a primary cell and at least one secondary cell, and the apparatus communicates with a secondary cell group including a primary cell and at least one secondary cell; detecting a radio link failure between the device and the primary cell of the secondary cell group; and Providing information based on the radio link failure to the primary cell of the primary cell group, wherein, when there is a valid conditional primary cell PSCell change execution command pending for the secondary cell group, the information indicates that the radio link failure occurred on the secondary cell group while waiting for the primary cell PSCell change execution command of the conditional secondary cell group to be completed.

2. The apparatus of claim 1 , wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to at least: Information configured by the primary cell of the secondary cell group is transmitted via its radio link or a radio link of the primary cell of the primary cell group.

3. The apparatus according to any one of claims 1 or 2, wherein the information is further configured to notify the primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration.

4. The apparatus according to claim 3, wherein the information configured to notify the primary cell of the primary cell group of an identity value associated with at least one candidate cell from the secondary cell group for which the apparatus has a valid conditional change configuration is a bitmap, and the bitmap is configured to indicate the at least one candidate cell within a measurement cell list.

5. The apparatus according to any one of claims 1 to 2, wherein the information is further configured to notify the primary cell of the primary cell group of a conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of the primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

6. The apparatus according to claim 5, wherein the information is further configured to: notify the primary cell of the primary cell group of the signal measurement of the at least one candidate cell from the secondary cell group by providing a difference in signal strength between at least one candidate cell from the secondary cell group and a corresponding conditional change execution condition of the conditional cell change associated with the at least one candidate cell from the secondary cell group.

7. The apparatus according to any one of claims 1 to 2, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to at least: receiving a radio resource control message from the primary cell of the primary cell group, the radio resource control message including a cell identity of a ready cell from the secondary cell group to change to; and Based on the cell identity, a cell change is performed from the primary cell of the secondary cell group to the ready cell from the secondary cell group.

8. The apparatus according to any one of claims 1 to 2, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to at least: receiving a radio resource control reconfiguration message from the primary cell of the primary cell group, the radio resource control reconfiguration message including a cell identity of a cell from the secondary cell group to be changed to, excluding a ready cell; and Based on the cell identity, a cell change is performed from the primary cell of the secondary cell group to a not ready cell from the secondary cell group.

9. The apparatus according to any one of claims 1 to 2, wherein the apparatus is a user equipment.

10. An apparatus for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least: communicating with at least one other device, wherein the other device is configured to operate in a dual connectivity mode, communicate with a primary cell group, and communicate with a secondary cell group, the primary cell group including the device as a primary cell, and at least one secondary cell, and the secondary cell group including the primary cell and at least one secondary cell; Information based on a radio link failure between the at least one other device and the primary cell of the secondary cell group is received from the at least one other device, wherein, when there is a valid conditional primary cell PSCell change execution command of the secondary cell group pending, the information indicates that the radio link failure occurred on the secondary cell group while waiting for the primary cell PSCell change execution command of the conditional secondary cell group to be completed.

11. The apparatus according to claim 10, wherein the information is further configured to inform the apparatus of an identity value associated with at least one candidate cell from the secondary cell group for which the at least one further apparatus has a valid conditional change configuration.

12. The apparatus according to claim 11, wherein the information configured to notify the apparatus of the identity value associated with the at least one candidate cell from the secondary cell group for which the at least one further apparatus has a valid conditional change configuration is a bitmap, the bitmap being configured to indicate the at least one candidate cell within a measured cell list.

13. An apparatus according to any one of claims 10 to 12, wherein the information is further configured to notify the apparatus of a conditional change execution condition associated with at least one candidate cell from the secondary cell group, and signal measurements of the primary cell of the secondary cell group and the at least one candidate cell from the secondary cell group.

14. An apparatus according to claim 13, wherein the information is further configured to: notify the apparatus of the signal measurement of the at least one candidate cell from the secondary cell group by providing a difference in signal strength between the at least one candidate cell from the secondary cell group and the corresponding conditional change execution condition of the conditional cell change associated with the at least one candidate cell from the secondary cell group.

15. The apparatus according to any one of claims 10 to 12, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to at least: generating a radio resource control message based on the information, the radio resource control message including a cell identity of a ready cell from the secondary cell group to which to change; and The radio resource control message is provided to the at least one further apparatus such that the at least one further apparatus is configured to perform a cell change from the primary cell of the secondary cell group to the ready cell from the secondary cell group based on the cell identity.

16. The apparatus according to any one of claims 10 to 12, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to at least: generating a radio resource control reconfiguration message based on the information, the radio resource control reconfiguration message including a cell identity of a cell from the secondary cell group to be changed to, excluding the ready cell; and The radio resource control message is provided to the at least one further apparatus such that the at least one further apparatus is configured to perform a cell change from the primary cell of the secondary cell group to a not ready cell from the secondary cell group based on the cell identity.

17. The apparatus according to any one of claims 10 to 12, wherein the apparatus is a master node.

18. An apparatus for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to at least: communicating with at least one other device, wherein the other device is configured to operate in a dual connectivity mode, communicate with a primary cell group, and communicate with a secondary cell group, the primary cell group including a primary cell and at least one secondary cell, the secondary cell group including the primary cell and the device as a secondary cell; as well as Information for a cell change from the primary cell of the secondary cell group is received from the at least one additional device, wherein, when there is a valid conditional primary cell PSCell change execution command of the secondary cell group pending, the information indicates that a radio link failure is detected on the secondary cell group while waiting for completion of the conditional primary cell PSCell change execution command of the secondary cell group.

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