Special bearing processing method and device and readable medium

Abstract

The invention provides a dedicated bearer processing method. The method comprises the following steps: receiving a deactivated user plane connection message sent by an AMF (Access and Mobility Management Function) entity; and notifying a policy control function (PCF), a user plane function (UPF) and the AMF to delete a dedicated bearer and a tunnel for transmitting data under the condition that a user plane connection activation message sent by the AMF is not received within a preset duration. In the idle state of the mobile terminal, the N3 tunnel and the voice dedicated bearer are deleted in a delayed manner, so that voice call drop can be prevented, the voice call continuity is improved, and the resource consumption of a core network is reduced. The invention further provides a special bearing processing device and a readable medium.

Description

Technical Field

[0001] The present disclosure relates to the field of communication technology, and in particular to a dedicated bearer processing method, device and readable medium. Background Art

[0002] Figure 1 It is a schematic diagram of the 5G system architecture, in which the NFs (Network Functions) related to SMF (Service Management Function) include: AMF (Access and Mobility Management Function), UDM (Unified Data Management), PCF (Policy Control Function), and UPF (User Plane Function).

[0003] At present, a common scenario in the existing network is that when a user makes a VONR (Voice over NR) voice call, when the connected UE enters an area without wireless signals, such as an elevator or tunnel, the RAN (Radio Access Network) will initiate a connection release request (AN Release), resulting in a short-term poor wireless environment and caused by dropped calls. For example: After the AMF receives the UE Context Release message sent by the RAN due to the poor wireless environment, it sends a deactivation user plane connection message to the SMF. After receiving the deactivation user plane connection message, the SMF deletes the N3 tunnel resources, resulting in dropped voice calls. At the same time, in the idle state, the dedicated voice bearer will always exist, resulting in excessive consumption of dedicated bearer resources in the core network. Summary of the invention

[0004] The present disclosure provides a dedicated bearer processing method, device and readable medium.

[0005] In a first aspect, an embodiment of the present disclosure provides a dedicated bearer processing method, the method comprising:

[0006] Receiving a deactivation user plane connection message sent by the access and mobility management function entity AMF;

[0007] If the activation user plane connection message sent by the AMF is not received within the preset time, the policy control function entity PCF, the user plane function entity UPF and the AMF are notified to delete the dedicated bearer and the tunnel used to transmit data.

[0008] On the other hand, an embodiment of the present disclosure also provides a dedicated bearer processing device, comprising: one or more processors; a storage device, on which one or more programs are stored; when the one or more programs are executed by the one or more processors, the one or more processors implement the dedicated bearer processing method as described above; one or more I / O interfaces, connected between the processor and the storage device, configured to implement information interaction between the processor and the storage device.

[0009] On the other hand, an embodiment of the present disclosure further provides a computer-readable medium having a computer program stored thereon, wherein the program, when executed, implements the dedicated bearer processing method as described above.

[0010] The dedicated bearer processing method provided by the embodiment of the present disclosure receives a deactivation user plane connection message sent by the access and mobility management function entity AMF; if the activation user plane connection message sent by the AMF is not received within a preset time, the policy control function entity PCF, the user plane function entity UPF and the AMF are notified to delete the dedicated bearer and the tunnel used to transmit data. In the idle state of the mobile terminal, the delayed deletion of the N3 tunnel and the voice dedicated bearer can prevent voice call drops, improve the continuity of voice calls, and reduce the consumption of core network resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the 5G system architecture in the public technology;

[0012] Figure 2 Schematic diagram of the dedicated bearer processing flow provided in the embodiment of the present disclosure Figure 1 ;

[0013] Figure 3 Schematic diagram of the dedicated bearer processing flow provided in the embodiment of the present disclosure Figure 2 ;

[0014] Figure 4 Schematic diagram of the dedicated bearer processing flow provided in the embodiment of the present disclosure Figure 3 ;

[0015] Figure 5 A flowchart of delayed deletion of voice dedicated bearer and N3 tunnel resources in a VONR scenario provided by a specific example of the present disclosure;

[0016] Figure 6 A flowchart of reserving voice dedicated bearer and N3 tunnel resources in a VONR scenario provided by a specific example of the present disclosure;

[0017] Figure 7 A schematic diagram of the structure of a dedicated load-bearing processing device provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] Example embodiments will be described more fully below with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, the purpose of providing these embodiments is to make the present disclosure thorough and complete and to enable those skilled in the art to fully understand the scope of the present disclosure.

[0019] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0020] The terms used herein are only used to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "made of" are used in this specification, the presence of the features, wholes, steps, operations, elements and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof is not excluded.

[0021] The embodiments described herein may be described with reference to plan views and / or cross-sectional views by means of idealized schematic diagrams of the present disclosure. Therefore, the example illustrations may be modified according to manufacturing techniques and / or tolerances. Therefore, the embodiments are not limited to the embodiments shown in the accompanying drawings, but include modifications of the configurations formed based on the manufacturing process. Therefore, the regions illustrated in the accompanying drawings have schematic properties, and the shapes of the regions shown in the figures illustrate the specific shapes of the regions of the elements, but are not intended to be limiting.

[0022] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted as having an idealized or overly formal meaning unless explicitly defined as such herein.

[0023] In order to solve the problem of dropped calls in idle state of user terminals and excessive consumption of dedicated voice bearer resources, the embodiments of the present disclosure propose a dedicated bearer processing method, which can improve voice continuity and optimize dedicated bearer resources in idle state. The embodiments of the present disclosure can be applied to VONR scenarios. In the implementation of the present disclosure, the dedicated bearer is a dedicated voice bearer as an example for explanation.

[0024] like Figure 2 As shown, the dedicated bearer processing method is applied to SMF, comprising the following steps:

[0025] Step S11, receiving the deactivation user plane connection message sent by AMF.

[0026] Due to the poor wireless environment, (R)AN sends a UE Context Release message to AMF, and AMF sends a deactivate user plane connection message to SMF. If SMF receives the deactivate user plane connection message sent by AMF, it means that the wireless connection between UE and (R)AN is disconnected at this time. For example, the UE enters an elevator, tunnel or other area without wireless signal.

[0027] Step S12, if the activation user plane connection message sent by AMF is not received within the preset time, notify PCF, UPF and AMF to delete the dedicated bearer and the tunnel used to transmit data.

[0028] In the disclosed embodiment, the tunnel used to transmit data is the N3 tunnel. A timer is set in the SMF, and the preset duration is the timing duration of the timer. When the SMF receives the deactivation user plane connection message sent by the AMF, the SMF starts the timer. If the activation user plane connection message sent by the AMF is not received before the timer expires, it means that the wireless connection between the current UE and the (R)AN is still disconnected, that is, it is in an idle state. Then, the SMF can notify the PCF, UPF and AMF to delete the voice dedicated bearer and the N3 tunnel, which can reduce the signaling interaction between the core network element and the UE, thereby saving the core network resource consumption.

[0029] The dedicated bearer processing method provided by the embodiment of the present disclosure receives a deactivation user plane connection message sent by the access and mobility management function entity AMF; if no activation user plane connection message sent by AMF is received within a preset time, the PCF, UPF and AMF are notified to delete the dedicated bearer and the tunnel used to transmit data. When the mobile terminal is in an idle state, the delayed deletion of the N3 tunnel and the voice dedicated bearer can prevent voice call drops, improve the continuity of voice calls, and reduce the consumption of core network resources.

[0030] In some embodiments, the notifying PCF, UPF and AMF to delete the dedicated bearer and the tunnel used to transmit data (i.e., step S12) includes the following steps: notifying PCF to delete the first dedicated bearer information of the dedicated bearer; notifying AMF to release the Evolved Packet System Bearer Identity (Evolved Packet System Bearer Identity) of the dedicated bearer; notifying UPF to delete the second dedicated bearer information of the dedicated bearer and the tunnel used to transmit data.

[0031] In some embodiments, the first dedicated bearer information is dedicated bearer policy information.

[0032] In some embodiments, the second dedicated bearer information is dedicated bearer service quality flow information (QosFlow), and the dedicated bearer service quality flow information (QosFlow) may include one or any combination of the following: packet detection rule information (Packet Detection Rule, PDR), forwarding action rule information (Forwarding Action Rule, FAR), and quality of service enforcement rule information (QoS Enforcement Rules, QER).

[0033] When the dedicated bearer is deleted in the idle state, the UE is in the IDLE state. When the N1 message is transmitted to the UE, it is very likely that the N1 message cannot be transmitted. The transmission of the N1 message depends on the AMF implementation. According to the 23.502 protocol description, when the AMF supports the ATC (Asynchronous Type Communication) function, the N1 message will be cached and sent to the UE when the AMF enters the connected state. However, not all AMF manufacturers currently support the ATC function, which brings compatibility issues to AMF devices.

[0034] In order to solve the above problems, in some embodiments, Figure 3 As shown, after receiving the deactivation user plane connection message sent by the AMF (ie, step S11), the dedicated bearer processing method may further include the following steps:

[0035] Step S21: When no activation user plane connection message sent by the AMF is received within a preset time period, cache the third dedicated bearer information of the dedicated bearer.

[0036] In some embodiments, the third dedicated bearer information may include quality of service flow policy information (QosRule).

[0037] Step S22, when the AMF enters the connected state, the third dedicated bearer information is sent to the AMF, so that the AMF notifies the user equipment to delete the third dedicated bearer information.

[0038] If the activation user plane connection message sent by AMF is not received before the timer expires, it means that the wireless connection between the current UE and (R)AN is still disconnected, that is, it is in an idle state, then SMF can also cache the QosRule of the voice dedicated bearer locally. When the wireless connection between the UE and (R)AN is established again, AMF enters the connected state, at which time SMF sends the locally cached QosRule of the voice dedicated bearer to AMF, and AMF notifies UE to delete the QosRule of the voice dedicated bearer. In this way, even if AMF does not support the ATC function, it can send N1 messages to UE, which can ensure good compatibility without relying on AMF, save the voice dedicated bearer resources of UE and core network, and also ensure the consistency of voice dedicated bearer resources on UE side and core network side.

[0039] It should be noted that the execution order of step S21 and step S12 is not limited.

[0040] In some embodiments, after sending the third dedicated bearer information to AMF (ie, step S22), the dedicated bearer processing method may further include the following steps: upon receiving a session update message returned by AMF, locally deleting the third dedicated bearer information of the dedicated bearer.

[0041] In some embodiments, when the AMF enters the connected state, the third dedicated bearer information is sent to the AMF (i.e., step S22), including the following steps: upon receiving the activation user plane connection message sent by the AMF, an information transfer message is sent to the AMF, and the information transfer message carries the third dedicated bearer information. In the case of a service request process initiated by the UE or a forward update process of activating a UP connection after paging, the AMF sends an activation user plane connection message to the SMF, at which time a connection has been established between the UE and the (R)AN.

[0042] In some embodiments, the information transfer message carries an N1 instruction (N1 ModComd), and the N1 instruction carries the third dedicated bearer information.

[0043] When the wireless environment improves and the UE re-establishes the connection with the (R)AN, the AMF sends an activation user plane connection message to the SMF. After the SMF receives the activation user plane connection message sent by the AMF, it carries the third dedicated bearer information of the dedicated bearer in the information transfer message and sends it to the AMF. In some embodiments, the information transfer message may be a Nammf_Communication_N1N2MessageTransfer message, which carries N1 ModComd, and N1 ModComd carries the third dedicated bearer information. After receiving the Nammf_Communication_N1N2MessageTransfer message, the AMF obtains the N1ModComd carried therein, and sends the N1 ModComd to the UE through the (R)AN, so that the UE deletes the third dedicated bearer information locally.

[0044] In some embodiments, after sending the third dedicated bearer information to the AMF (i.e., step S22), the dedicated bearer processing method may further include the following steps: upon receiving a session update message returned by the AMF, locally deleting the third dedicated bearer information. After the UE locally deletes the third dedicated bearer information, it returns an N1 response message (N1 ACK) to the AMF through the (R)AN. After receiving the N1 ACK message, the AMF sends a session update message to the SMF. After receiving the session update message, the SMF locally deletes the third dedicated bearer information.

[0045] In some embodiments, Figure 4 As shown, after receiving the deactivation user plane connection message sent by the AMF (ie, step S11), the dedicated bearer processing method may further include the following steps:

[0046] Step S12', when the activation user plane connection message sent by AMF is received within the preset time, the tunnel and dedicated bearer used to transmit data are reserved.

[0047] If SMF receives the activation user plane connection message sent by AMF before the timer expires, indicating that the wireless connection between the current UE and (R)AN has been restored to the connected state, the N3 tunnel and voice dedicated bearer are retained to ensure the continuity of the voice call.

[0048] To clearly illustrate the solution of the embodiment of the present disclosure, the following Figure 5 and Figure 6 , the dedicated bearer processing flow is described in detail through two specific examples. Figure 5The following is a flowchart of delaying the deletion of voice dedicated bearers and N3 tunnel resources in a VONR scenario (scenario 1) provided by a specific example of the present disclosure. Figure 5 As shown, the process of delaying the deletion of voice dedicated bearer and N3 tunnel resources includes the following steps:

[0049] Step 1: When the UE is in a connected state, the PCF establishes a GBR (Guaranteed Bit Rate) dedicated bearer QoS, and the dedicated bearer is established successfully.

[0050] Step 2a, (R)AN initiates a connection release request (AN Release), and AMF transparently transmits the connection release request to SMF;

[0051] Step 2b, AMF sends Nsmf_PDU_Session_UpdateSMContextRequest message to SMF;

[0052] Step 3, SMF and UPF interact with each other via N4 message;

[0053] Step 4a, SMF replies Nsmf_PDUSession_UpdateSMContextRsponse message to AMF, indicating that the AN Release process is successful;

[0054] Step 4b, SMF starts the timer for delaying the deletion of the dedicated bearer;

[0055] Steps 5a-5b, when the timer for delaying the deletion of the dedicated bearer times out, the SMF notifies the PCF to delete the dedicated bearer policy information;

[0056] Step 6: SMF notifies AMF to release the EBI under the dedicated bearer;

[0057] Step 7: SMF instructs UPF to delete QosFlow information and N3 tunnel resources. The second dedicated bearer information may include PDR, FAR, and QER.

[0058] Step 8, SMF stores the QosRule information that has been deleted but not notified to the UE;

[0059] Step 9: SMF receives the activation user plane connection message sent by AMF and enters the connection state;

[0060] Step 10a, SMF sends a Namf_Communication_N1N2MessageTransfer message to AMF, which carries the N1 command (N1 ModCmd), and the N1 ModCmd includes the QosRule information;

[0061] Steps 10b-10c, AMF transparently transmits N1 ModCmd to UE via (R)AN;

[0062] In steps 10d-10e, the UE transparently transmits the N1 Ack message to the AMF through the (R)AN.

[0063] Step 11, AMF sends Nsmf_PDUSession_UpdateSMContextRequest message to SMF.

[0064] Step 12: SMF clears the stored QosRule information.

[0065] It can be seen from the above steps 1-12 that in this scenario, when the user is making a VONR voice call, when the connected UE enters an area without a wireless signal (for example, an elevator or tunnel), the (R)AN initiates an AN Release connection release request, and the SMF starts a delayed deletion of the dedicated bearer timer. After the delayed deletion of the dedicated bearer timer expires, the original voice dedicated bearer and N3 tunnel resources are deleted.

[0066] Figure 6 The following is a flowchart of reserving voice dedicated bearer and N3 tunnel resources in a VONR scenario (scenario 2) provided in a specific example of the present disclosure. Figure 6 As shown, the process of the flowchart of reserving voice dedicated bearer and N3 tunnel resources includes the following steps:

[0067] Step 1: When the UE is in a connected state, the PCF establishes a GBR (Guaranteed Bit Rate) dedicated bearer QoS, and the dedicated bearer is established successfully.

[0068] Step 2a: RAN initiates a connection release request (AN Release), and AMF transparently transmits the connection release request to SMF;

[0069] Step 2b, AMF sends Nsmf_PDU_Session_UpdateSMContextRequest message to SMF;

[0070] Step 3, SMF and UPF interact with each other via N4 message;

[0071] Step 4a, SMF replies Nsmf_PDUSession_UpdateSMContextRsponse message to AMF, indicating that the AN Release process is successful;

[0072] Step 4b, SMF starts the timer for delaying the deletion of the dedicated bearer;

[0073] Step 5: Before the delayed deletion of the dedicated bearer timer expires, if SMF receives the activation user plane connection message sent by AMF, the delayed deletion of the dedicated bearer timer is cleared and the original voice dedicated bearer and N3 tunnel resources continue to be retained.

[0074] The difference between scenario 2 and scenario 1 is that SMF has received the activation user plane connection message sent by AMF before the delayed deletion of the dedicated bearer timer expires, and continues to retain the original voice dedicated bearer and N3 tunnel resources.

[0075] In order to solve the problem of dropped calls in idle state and excessive consumption of voice dedicated bearer resources, the embodiment of the present disclosure proposes a dedicated bearer processing method, which can improve voice continuity and optimize voice dedicated bearer resources in idle state. SMF supports delayed release of N3 tunnel resources after receiving a deactivation user plane connection message. In idle state, SMF also supports deletion of voice dedicated bearers to save voice dedicated bearer resources of UE and core network. SMF receives a deactivation user plane connection message sent by AMF and starts a delayed deletion dedicated bearer timer. If SMF receives an activation user plane connection message sent by AMF before the delayed deletion dedicated bearer timer times out, the delayed deletion dedicated bearer timer is closed, and the N3 tunnel resources and the original voice dedicated bearer are continued to be reserved, which can improve voice call continuity; if SMF does not receive an activation user plane connection message sent by AMF before the delayed deletion dedicated bearer timer times out, the N3 tunnel resources and the original voice dedicated bearer are deleted, saving voice dedicated bearer resources of UE and core network. In addition, in order to solve the problem that the N1 message cannot be delivered after deleting the dedicated voice bearer in the idle state, the SMF in the disclosed embodiment first caches the dedicated voice bearer information to be deleted. After the connection state is restored, the SMF delivers the N1 message to the AMF, and the AMF notifies the UE. This implementation does not rely on the AMF, ensuring good compatibility and consistency of the dedicated voice bearer resources on the core network side and the UE side.

[0076] The disclosed embodiment also provides a dedicated load processing device, such as Figure 7 As shown, including:

[0077] at least one processor 701;

[0078] A memory 702 storing at least one program, when the at least one program is executed by the at least one processor, the at least one processor implements the dedicated bearer processing method provided in the above embodiments;

[0079] At least one I / O interface 703 is connected between the processor and the memory and is configured to implement information exchange between the processor and the memory.

[0080] Among them, the processor 701 is a device with data processing capabilities, including but not limited to a central processing unit (CPU); the memory 702 is a device with data storage capabilities, including but not limited to random access memory (RAM, more specifically SDRAM, DDR, etc.), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory (FLASH); the I / O interface (read-write interface) 703 is connected between the processor 701 and the memory 702, and can realize information interaction between the processor 701 and the memory 602, including but not limited to a data bus (Bus), etc.

[0081] In some embodiments, the processor 701 , the memory 702 , and the I / O interface 703 are connected to each other through a bus, and further connected to other components of the computing device.

[0082] The embodiments of the present disclosure further provide a computer-readable medium on which a computer program is stored, wherein when the computer program is executed, the dedicated bearer processing method provided in the aforementioned embodiments is implemented.

[0083] It will be appreciated by those skilled in the art that all or some of the steps in the method disclosed above, the functional modules / units in the device may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0084] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for limiting purposes. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly stated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A dedicated bearer processing method, characterized in that: The method comprises: Receiving a deactivation user plane connection message sent by the access and mobility management function entity AMF; If the activation user plane connection message sent by the AMF is not received within the preset time, the policy control function entity PCF, the user plane function entity UPF and the AMF are notified to delete the dedicated bearer and the tunnel used to transmit data.

2. The method according to claim 1, characterized in that The notifying policy control function entity PCF, user plane function entity UPF and AMF to delete a dedicated bearer and a tunnel for transmitting data includes: Notify the PCF to delete the first dedicated bearer information of the dedicated bearer; Notify the AMF to release the evolved packet system bearer identifier of the dedicated bearer; Notify UPF to delete the second dedicated bearer information of the dedicated bearer and the tunnel used to transmit data.

3. The method according to claim 1, characterized in that After receiving the deactivation user plane connection message sent by the access and mobility management function entity AMF, the method further includes: If no activation user plane connection message sent by the AMF is received within a preset time period, cache the third dedicated bearer information of the dedicated bearer; When the AMF enters the connected state, the third dedicated bearer information is sent to the AMF, so that the AMF notifies the user equipment to delete the third dedicated bearer information.

4. The method according to claim 3, characterized in that The sending the third dedicated bearer information to the AMF when the AMF enters a connected state includes: Upon receiving the activation user plane connection message sent by the AMF, an information transfer message is sent to the AMF, wherein the information transfer message carries the third dedicated bearer information.

5. The method according to claim 4, characterized in that The information transfer message carries an N1 instruction, and the N1 instruction carries the third dedicated bearer information.

6. The method according to claim 3, characterized in that After sending the third dedicated bearer information to the AMF, the method further includes: Upon receiving the session update message returned by the AMF, the third dedicated bearer information is deleted locally.

7. The method according to claim 3, characterized in that The third dedicated bearer information includes quality of service flow strategy information.

8. The method according to any one of claims 1 to 7, characterized in that: After receiving the deactivation user plane connection message sent by the access and mobility management function entity AMF, the method further includes: When the activation user plane connection message sent by the AMF is received within the preset duration, the tunnel for transmitting data and the dedicated bearer are retained.

9. A dedicated load handling device, comprising: one or more processors; a storage device having one or more programs stored thereon; When the one or more programs are executed by the one or more processors, the one or more processors implement the dedicated bearer processing method according to any one of claims 1 to 8; One or more I / O interfaces are connected between the processor and the storage device and are configured to implement information interaction between the processor and the storage device.

10. A computer readable medium having a computer program stored thereon, wherein: When the program is executed, the dedicated bearer processing method according to any one of claims 1 to 8 is implemented.

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