Wireless communication system and method for providing communication services to a mobile terminal - Patents.com

Abstract

A wireless communication system and method for providing communication services to a mobile terminal are provided. According to one embodiment, a method for providing communication services to a mobile terminal by a communication network includes the steps of: detecting, by the mobile terminal performing a predetermined data processing procedure, that the mobile terminal is temporarily unreachable in the communication network; responsive to the detection, transmitting an indication that the mobile terminal is temporarily unreachable in the communication network to a component for providing communication services; and responsive to receiving the indication, providing communication services to the mobile terminal taking into account that the mobile terminal is temporarily unreachable.

Description

[Technical field]

[0001] The present disclosure relates to a communication system and method for providing communication services to a mobile terminal. [Background technology]

[0002] In mobile radio communication systems, a mobile terminal may become unavailable for minutes, for example when performing an upgrade such as an operating system (OS) update, etc. In that case, the mobile terminal may become unavailable (and thus unreachable on the network side) if, for example, the application server or the core network is not aware of it.

[0003] Furthermore, when a mobile terminal becomes unavailable for minutes, e.g. due to an operating system update, the communication system typically performs a detach (deregistration) procedure and releases all sessions (e.g. Packet Data Unit (PDU) sessions) of the mobile terminal. This can be triggered by the mobile terminal or by the network side. This means that the mobile terminal and the network release (delete) the Mobility Management (MM) and Session Management (SM) contexts and the IP (Internet Protocol) connections. When the mobile terminal becomes available again (e.g. rebooted after an update), it has to perform corresponding procedures to re-establish the communication, such as re-registration and re-establishment of the sessions. This causes a lot of signaling in the communication system. Summary of the Invention

[0004] Therefore, an approach that allows for better handling of temporary unavailability of mobile terminals is desirable.

[0005] According to one embodiment, there is provided a method for a communications network providing communications services to a mobile terminal, the method comprising the steps of: detecting, by the mobile terminal performing a predetermined data processing procedure (e.g., an Operating System (OS) update, manual PLMN selection, etc.), that the mobile terminal is temporarily unreachable in the communications network; in response to the detection, transmitting an indication that the mobile terminal is temporarily unreachable in the communications network to a component for providing communications services; and in response to receiving the indication, providing the communications services to the mobile terminal taking into account that the mobile terminal is temporarily unreachable in the communications network. and providing information to an application function regarding periods during which the communications network is temporarily unreachable. and starting a backoff timer due to unreachability.

[0006] According to another embodiment, there is provided a (wireless) communication system according to the method described above. [Brief description of the drawings]

[0007] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the following description, various aspects are described with reference to the following drawings: [Figure 1] FIG. 1 illustrates a wireless communication system. [Diagram 2] FIG. 2 illustrates components involved in detaching a mobile terminal from a communication network. [Diagram 3] FIG. 2 is a message flow diagram illustrating soft detachment of a mobile terminal from a communications network. [Figure 4] 1 is a flow diagram illustrating a method in which a communications network provides communications services to a mobile terminal. [Diagram 5] FIG. 1 illustrates a wireless communication system according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following detailed description, reference is made to the accompanying drawings, which show by way of example certain details and aspects of the present disclosure in which the present invention may be practiced. Other aspects may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. Various aspects of the present disclosure are not necessarily mutually exclusive, as some aspects of the present disclosure may be combined with one or more other aspects of the present disclosure to form new aspects.

[0009] Various examples corresponding to aspects of the present disclosure are described below.

[0010] Example 1 is a method for a communications network to provide communications services to a mobile terminal as described above.

[0011] Example 2 is the method of example 1, wherein the indication is transmitted by the mobile terminal and the components providing the communication services include one or more core network components of the communication network.

[0012] Example 3 is the method of example 2, including sending an indication along with the unsubscribe message and / or the subscribe message.

[0013] Example 4 is the method of example 2 or example 3, wherein the core network component is an access and mobility management function and / or a session management function and / or an integrated data management function and / or a policy control function and / or a network publishing function and / or a network data analysis function.

[0014] Example 5 is the method of example 1, wherein the indication is sent by an access and mobility management function and / or a network data analysis function and / or a session management function and / or an integrated data management and / or a policy control function and / or a network publishing function of the communication network, and the component for providing the communication service is an application function.

[0015] Example 6 is the method of any one of examples 1-5, wherein the indication includes a specification of why the mobile terminal is temporarily unreachable from the communications network.

[0016] Example 7 is the method of any one of Examples 1 to 6, wherein the indication includes a specification of a maximum period of time that the mobile terminal is unreachable from the communication network, and communication services are provided to the mobile terminal taking into account the maximum period of time.

[0017] Example 8 is the method of example 7, including estimating the maximum duration by network analysis.

[0018] Example 9 is the method of any one of Examples 1-8, where the predetermined data processing procedure is software updating of the mobile terminal in the communication network and / or selection of a public land mobile network and / or re-registration of the mobile terminal.

[0019] Example 10 is the method of any one of Examples 1-9, where the communication service includes providing one or more communication sessions to the mobile terminal.

[0020] Example 11 is the method of example 10, in which providing communication services to the mobile terminal in response to the mobile terminal being temporarily unreachable in the communication network includes maintaining one or more communication sessions established before the mobile terminal became temporarily unreachable, and providing the maintained one or more communication sessions to the mobile terminal when the mobile terminal becomes reachable again.

[0021] Example 12 is the method of any one of Examples 1-11, wherein the communication services include providing downlink and uplink data to the mobile terminal.

[0022] Example 13 is the method of example 12, in which providing communication services to the mobile terminal considering that the mobile terminal is temporarily unreachable in the communication network includes initiating buffering of downlink data until the mobile terminal is reachable again; and initiating transmission of the buffered downlink data when the mobile terminal is reachable again.

[0023] Example 14 is any one of the methods of Examples 1 to 13, wherein the step of providing a communication service to the mobile terminal considering that the mobile terminal is temporarily unreachable in the communication network includes a step of maintaining a mobility management context, a session management context, or both of the mobile terminal.

[0024] Example 15 is the method of any one of Examples 1-14, further comprising transmitting the mobility management context, the session management context, or both, to the mobile terminal when the mobile terminal is again reachable from the communications network.

[0025] Example 16 provides a wireless communication system, the wireless communication system including a first communication system component configured to detect that the mobile terminal is temporarily unreachable in a communication network of the wireless communication system by the mobile terminal performing a predetermined data processing procedure, and a second communication system component, wherein in response to the detection, the first communication system component is configured to transmit an indication that the mobile terminal is temporarily unreachable in the communication network to the second communication system component, and in response to receiving the indication, the second communication system component is configured to provide communication services to the mobile terminal, taking into account that the mobile terminal is temporarily unreachable in the communication network.

[0026] Example 17 is the communication system of example 16, wherein the first communication system component is a mobile terminal and the second communication system component is a component of a core network of the communication system.

[0027] Example 18 is the communication system of example 17, wherein the core network component is an access and mobility management function.

[0028] Example 19 is the communication system of example 18, wherein the first communication system component is an access and mobility management function and the second communication system component is an application function.

[0029] It should be noted that one or more of the features of any of the above examples may be combined with any of the other examples, in particular the examples described in relation to a method are equally valid for a wireless communication system and vice versa.

[0030] According to further embodiments, a computer program and computer readable medium is provided that includes instructions which, when executed by a computer, cause the computer to perform the method of any one of the above examples.

[0031] Various examples are described in more detail below.

[0032] FIG. 1 illustrates a wireless communication system 100 configured in accordance with 5G (fifth generation), eg 5GS, as specified by 3GPP (3rd Generation Partnership Project).

[0033] The wireless communication system 100 includes mobile wireless terminals 102, such as User Equipment (UE) and Nano Equipment (NE). The mobile wireless terminals 102, also called subscriber terminals, form the terminal side, while the other components of the wireless communication system 100 described below are part of the mobile wireless communication network side, i.e. part of a mobile wireless communication network (e.g. Public Land Mobile Network, PLMN).

[0034] Furthermore, the wireless communication system 100 includes a radio access network 103 that may include a number of radio access network nodes, i.e., base stations configured to provide wireless access according to 5G (5th Generation) radio access technology (5G New Radio). It should be noted that the wireless communication system 100 may be configured according to LTE (Long Term Evolution) or other wireless communication standards, but 5G is used here as an example. Each radio access network node 103 is capable of providing wireless communication with a mobile wireless terminal device 102 over an air interface. It should be noted that the radio access network 103 may include any number of radio access network nodes.

[0035] The wireless communication system 100 further comprises a core network (5GC) 108 including an Access and Mobility Management Function (AMF) 101 connected to the RAN 103 and a Unified Data Management (UDM) 104. Here and in the following examples, the UDM may further comprise an actual UE subscription database, known for example as a Unified Data Repository (UDR). The core network 108 further comprises an Authentication Server Function (AUSF) 109 and one or more Policy Control Functions (PCFs), in this example a first PCF 106 and a second PCF 107.

[0036] The core network 108 further includes multiple Session Management Functions (SMFs), in this example a first Session Management Function (SMF) 110 and a second Session Management Function (SMF) 112, and multiple User Plane Functions (UPFs), in this example a first User Plane Function (UPF) 111 and a second User Plane Function (UPF) 113. The SMFs 110, 112 are for handling PDU (Protocol Data Unit) sessions, i.e. for creating, updating and deleting PDU sessions and for managing session contexts with the User Plane Functions (UPFs).

[0037] The core network 108 further includes an Application Function (AF) 105. Although the AF 105 is shown as being directly connected to the SMFs 110, 112 and the PCFs 106, 107, it may also be connected to those SMFs and PCMs via a Network Exposure Function (NEF), particularly if the AF 105 is maintained by a third party (i.e. a party other than the operator of the mobile radio communication system 100), in which case all communication between the core network functions and the AF (and vice versa) is via the NEF.

[0038] The AF 105 allows an application to request the 5G system 100 to support a specific QoS (Quality of Service) policy for a UE 102 that establishes a PDU session that provides communication services to the application.

[0039] The SMF 110, 112 is for handling PDU (Protocol Data Unit) sessions, i.e. creating, updating and deleting PDU sessions and managing the session context with the User Plane Function (UPF).

[0040] The RAN 103 and the core network 108 form the network side of the mobile radio communication system, i.e., a (mobile radio) communication network. The mobile radio communication network and a mobile terminal that accesses the mobile radio communication network together form the mobile radio communication system.

[0041] The UE 102 may perform an upgrade, such as an operating system (OS) update. For example, the UE 102 receives a binary update file and decides to perform an upgrade procedure at midnight. The UE 102 then starts the corresponding upgrade procedure at midnight and becomes unreachable from the network side, e.g., unreachable and unavailable for (e.g.) 5 minutes starting from midnight. In particular, the UE 102 is not reachable by the application functions 105.

[0042] Furthermore, this may result in the UE 102 being unavailable for detachment (and thus becoming unreachable) followed by re-registration and re-establishment of the communication session, resulting in a lot of signalling, affecting, for example, the UE 102, the AMF 101, the respective SMFs 110, 112, the respective UPFs 111, 113 and all applications running on the UE 102 that use the communication network for communication.

[0043] FIG. 2 shows the components involved in detaching a UE.

[0044] A UE 201, e.g. corresponding to the UE 102, executes an application 202 that uses communication over a communication network. An AMF 203, e.g. corresponding to the AMF 101, maintains a mobility management (MM) context 204 for the UE 201. An SMF 205, e.g. corresponding to one of the SMFs 110, 112, maintains a session management (SM) context 206 for the UE 201 to provide the UE 201 with one or more communication sessions (used by the application 202 to send and receive data).

[0045] Detaching the UE 201 includes resetting or deleting application sockets, deleting the MM context 204, deleting the SM context 206, and deleting the user plane context of the UPF 207 (e.g., corresponding to one of the UPFs 111, 113).

[0046] When the UE becomes available again, the corresponding context needs to be re-established, which results in a large amount of signalling, e.g. registration procedures need to be performed (MM signalling), PDU session establishment procedures need to be performed (SM signalling) and application signalling such as IMS (IP Multimedia Subsystem) registration needs to be performed.

[0047] According to various embodiments, an approach is provided that allows to avoid this signaling effort in cases where the signaling may be unnecessary because the UE is temporarily unavailable, i.e. for a short period of time such as a few minutes (e.g. less than 5 minutes or less than 10 minutes, for example in the case of an update).

[0048] It should be noted that the following approach can also be applied to the manual PLMN selection use case: while searching for a PLMN, some UEs need to release the RRC (Radio Resource Control) connection (and MM context) since they are not reachable. According to various embodiments, the UE can reselect the PLMN (i.e., hold it until the user selects another PLMN) while the SM context does not need to be released.

[0049] FIG. 3 shows a message flow diagram 300 illustrating soft detachment of a mobile terminal.

[0050] A UE 301 (e.g., corresponding to UE 102) and an AMF serving the UE 301 (e.g., corresponding to AMF 101) are involved in the flow.

[0051] At 303, the UE 301 detects that the UE is temporarily unavailable (i.e., unreachable from the network side) because it has to perform a data processing operation due to a reboot caused by an update of the UE's operating system.

[0052] Accordingly, at 304, the UE 301 sends a deregistration request to the AMF 302. The deregistration request includes an indication that the UE 301 is temporarily unavailable, such as an indication of a soft detach, an indication that the UE is performing an OS update, an indication of a temporary failure, an indication of manual PLMN selection, etc.

[0053] In response to a deregistration request containing such an indication, the AMF 302 informs the UE 301 that it is temporarily unavailable, but retains (i.e., continues to store) the UE's MM and SM contexts at 305. For example, the AMF 302 releases the Non-Access Stratum (NAS) with the UE 301, but the AMF 302 does not delete the UE 301's contexts.

[0054] The AMF 302 responds at 306 with an unregistration-accept message.

[0055] Next, UE301 and AMF302 stop exchanging signaling information at 307.

[0056] Next, the UE 301 performs a data processing procedure, such as a reboot, since the UE is temporarily unavailable.

[0057] At 309, after restart, UE301 sends a registration request to AMF302, and AMF302 reuses the MM context and SM context that it held at 310.

[0058] In 311, the AMF 302 sends a registration accept message to the UE 301 and sends the MM and / or SM context to the UE 301, for example in a dedicated container. Before sending the registration accept message, if the AMF 302 determines that a context is required from another network function (e.g., from the SMF 205), then the AMF 302 can obtain a context (e.g., an SM context) from the respective network function (e.g., an SMF).

[0059] Table 1 lists the MM and SM context parameters that the AMF 302 may retain during periods when the UE 301 is unreachable.

[0060] [Table 1] TIFF0007619579000002.tif212170TIFF0007619579000003.tif240170TIFF0007619579000004.tif250168TIFF00076195790 00005.tif243170TIFF0007619579000006.tif229170TIFF0007619579000007.tif232170TIFF0007619579000008.tif161170

[0061] It should be noted that if the registration request sent in 309 is rerouted to a new AMF (other than AMF 302), the new AMF can obtain details of the AMF that last provided the service from UDM 104, thereby enabling the new AMF to extract the SM context from the (old) AMF 302.

[0062] Based on the policy of the AMF 302, the AMF 302 decides to store or buffer the downlink and uplink traffic of the UE 301. The AMF 302 information is for releasing the N3 interface between the RAN 103 and the UPF 113, 111 (e.g., AN release procedure). In this case, the UPF 113, 111 stores or buffers the traffic / session of the UE 301 and sends it back to the UE 301 after the registration procedure. Alternatively, the AMF 302 can decide to store or buffer in the RAN 103, in which case the AMF 302 informs the RAN 103 by indicating to store or buffer the traffic / session of the UE 301, 102. This indication to the RAN 103 can be done during or after the deregistration procedure.

[0063] If (the UE) 301 does not send a deregistration request in 304, after the UE has performed a data processing procedure (e.g. binary installation and reboot) that caused it to become temporarily unavailable, the UE may send a registration request indicating that it has become temporarily unavailable due to an update, i.e., a "binary update indicator", for example.

[0064] The AMF then makes a decision about what action is required and performs the necessary action, e.g. updating the state of the MM, but may also retain the information it still has (i.e. there may be little need to be done).

[0065] According to one embodiment, if there is any change in the UE's MM and SM capabilities after the update, the UE 301 may send the updated MM / SM capabilities to the AMF 302 in a registration request 309 (irrespective of whether the UE has sent a deregistration request 309). Based on the change in capabilities, the AMF 302 may perform a decision on the required action and perform the required action, if any.

[0066] As mentioned above, in addition to the high signaling effort, temporary unavailability of the UE 102 may lead to cases where the application function 105 is attempting to reach the UE 102 during the period of unavailability, but the application function 105 does not know why the UE 102 is not reachable, nor does it know for how long it will be unavailable.

[0067] According to various embodiments, a mechanism is provided to inform the AF 105, and thus third parties, that the UE 102 is temporarily unavailable. This may include an indication of the duration or an estimate of the duration of unreachability. The AF 105 or third party application server can then react accordingly. For example, if the application is a messaging service, the application server may buffer messages that cannot be sent and resend them after an indicated time, i.e. schedule downlink or uplink transmission of data based on the reachability of the UE 102.

[0068] Such an indication that the UE is temporarily unavailable, which may include an indication of the duration, may for example be provided to the AF 105 by the AMF 101. In other words, in the example of Fig. 3, the UE 301 transmits an indication to the AMF 105 that the UE is temporarily unreachable to perform a certain data processing procedure, and such an indication may be transmitted between other components of the communication system such that the AMF 101 transmits the indication to the AF 105. In that case, the AMF 101 may also be the component that detects that the UE is temporarily available, for example because the AMF 101 knows that the UE 301 needs to perform a data processing procedure (in which the AMF 101 may be involved) that makes it unreachable. The AMF 101 may also have knowledge from the UE 301 that the UE becomes temporarily unreachable.

[0069] A data processing procedure, for example registration, may involve the UE 102 having to wait a certain back-off period before it can re-register (e.g. in case of an update or other cases). In that case, the AMF 101 may inform the AF 105 about the period corresponding to a (UE-based) back-off timer (which it typically knows because the back-off timer is configured on the network side). This allows, for example, a third-party application server to decide when to re-transmit application data.

[0070] The network side can determine the period based on the backoff time set by the network (in case of registration with backoff) or other mechanisms such as information from the NWDAF (Network Data Analysis Function).

[0071] For example, the NWDAF provides "UE unreachable" statistics to the AMF 101 and / or directly to the AF 105. The AMF 101 and / or AF 105 can subscribe to UE unreachability analysis at the NWDAF. For example, the NWDAF collects input data from NFs (e.g., AMF, SMF, AF), determines a prediction of the duration of UE unreachability (e.g., UE may be unavailable for 5 minutes at 00.00 hours), and provides the predicted duration to the consumer (e.g., AMF, AF). Alternatively, the NWDAF can provide statistical information to the AMF 101 and / or AF 105, and based on this information, the AMF 101 and / or AF 105 can determine the duration of UE unreachability.

[0072] In summary, according to various embodiments, a method is provided as shown in FIG.

[0073] FIG. 4 shows a flow diagram 400 illustrating a method by which a communication network provides communication services to a mobile terminal.

[0074] At 401, the mobile terminal detects that the mobile terminal is temporarily unreachable in the communication network by performing a predetermined data processing procedure.

[0075] At 402, in response to the detection, an indication that the mobile terminal is temporarily unreachable in the communications network is transmitted. The indication is transmitted to a component providing communications services.

[0076] At 403, in response to receiving the indication, communication services are provided to the mobile terminal, taking into account that the mobile terminal is temporarily unreachable from the communication network.

[0077] In other words, according to various embodiments, when a mobile terminal becomes temporarily available to perform certain data processing procedures, such as updating or re-registration (including waiting for a back-off period), components supporting the provision of communication services can be notified and react accordingly.

[0078] The indication may be sent by the mobile terminal itself or by a network side component, in particular a network function such as the AMF, SMF, PCF, UDM, NEF or NWDAF. The indication may for example be sent to an application function.

[0079] For example, if an indication is sent to the SMF and it is determined that the SM context needs to be stored, then the SMF notifies the AMF not to release the SM context of the mobile terminal. Based on the notification, the AMF keeps the context and performs further actions such as deregistration of the mobile terminal. Similarly, the same mechanism can be applied to other network functions such as PCF, UDM, NEF, i.e. based on the indication and the policy, the network function can decide not to release the UE context (e.g. SM or MM context or both) and notify the AMF and / or SMF not to release the context.

[0080] The components for providing communication services may also be informed of the period during which the mobile terminal is unable to reach the communication network and / or of the cause of the unavailability of the mobile terminal (why the mobile terminal is unable to reach the communication network).

[0081] For example, according to various embodiments, the application server may be informed as to why the mobile terminal is unreachable and / or for how long the mobile terminal will (likely) be unreachable.

[0082] When an indication is sent by the mobile terminal to a core network (e.g., AMF), the indication (e.g., in the form of a message such as a soft deregistration message) may be considered as an indication that the MM context and / or SM context (e.g., one or more sessions established for the mobile terminal) can be at least partially preserved to the core network.

[0083] To indicate the cause of unavailability, an indication (e.g., a message indicating that the mobile terminal is unreachable) may include a specification of a cause value. For example, a core network component (e.g., AMF) may send a cause value (e.g., instead of specifying the duration of the period during which the UE is unavailable) to the AF. The UE may send a cause value (e.g., specifying the cause or reason for the unavailability: e.g., "OS update", "temporary failure", "manual PLMN selection", etc.) to the network component. The network component may then forward the cause value to the AF to indicate that the UE is unreachable due to the cause indicated by the cause value. Based on the cause value, the AF may determine the local time and retry after expiration. The AF is also aware of the state of the mobile terminal. The core network component (e.g., AMF) may determine the cause value based on local policies and / or UE-provided information.

[0084] The indication that the mobile terminal is unable to reach the communications network may be an indication that the mobile terminal is unable to reach a core network of the wireless communications system.

[0085] FIG. 5 illustrates a wireless communication system 500 according to one embodiment.

[0086] The communication system 500 includes a first communication system component 501 and a second communication system component 502 configured to detect that the mobile terminal is temporarily (e.g., currently or in the near future) unreachable for a communication network of the wireless communication system by the mobile terminal executing a predetermined data processing procedure.

[0087] The first communications system component 501 is configured to, in response to the detection, transmit an indication 503 to the second communications system component 502 that the mobile terminal is temporarily unreachable in the communications network.

[0088] The second communications system component 502 is configured to, in response to receiving the indication, provide communications services to the mobile terminal, taking into account that the mobile terminal is temporarily unreachable from the communications network.

[0089] For example, according to various embodiments, one or more of the following are performed in a communication system:

[0090] The UE decides to perform a soft restart and sends a corresponding NAS or AS indicator to the AMF via the RAN.

[0091] The AMF does not release the UE context and does not inform the SMF to release one or more sessions of the UE based on an indication from the UE.

[0092] · The AMF determines an indication of the "unreachable time" based on the back-off timer (cause of UE becoming unreachable) and makes this indication available to the AF.

[0093] The NWDAF determines the analysis of the UE unavailability and delivers the output (e.g. unreachability prediction) to the consumers (AMF, AF).

[0094] The AF reschedules each downlink and / or uplink event involving data transmission to the UE based on the “unreachable time” metric.

[0095] The method can be performed and the components of the communication network configuration can be implemented, for example, by one or more circuits. A "circuit" can be understood as any kind of logic implementation entity, which can be a dedicated circuit or a processor that executes software stored in memory, firmware, or any combination thereof. Thus, a "circuit" can be a hardwired logic circuit or a programmable processor, for example a programmable logic circuit such as a microprocessor. A "circuit" can also be a processor that executes software, for example any kind of computer program. Other kinds of implementations of each of the above-mentioned functions can also be understood as a "circuit".

[0096] Although specific embodiments have been described, it should be understood by those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the disclosed embodiments as defined by the appended claims, the scope of which is thus indicated by the claims and is intended to include all modifications that come within the meaning and range of equivalence of the claims.

Claims

1. 1. A method of a communications network providing a communications service to a mobile terminal, the method comprising: detecting, by the mobile terminal performing a predetermined data processing procedure, that the mobile terminal is temporarily unreachable from the communications network; said mobile terminal, in response to said detection, transmitting an indication that said mobile terminal is temporarily unreachable in said communications network to a core network component of said communications network for providing communications services; in response to receiving the indication, providing said communications services to said mobile terminal taking into account that said mobile terminal is temporarily unreachable from said communications network and providing information to an application function regarding the period during which said communications network is temporarily unreachable; starting a back-off timer due to unreachability. method.

2. 2. The method of claim 1, wherein the core network component is an access and mobility management function and / or a session management function and / or an integrated data management function and / or a policy control function and / or a network publishing function and / or a network data analysis function.

3. The method of claim 1 , wherein the indication includes a description of why the mobile terminal is temporarily unreachable to the communications network.

4. The method of claim 1 , wherein the indication includes a specification of a maximum period during which the mobile terminal is unreachable from the communications network, and the communications service is provided to the mobile terminal taking into account the maximum period.

5. 2. The method of claim 1, wherein the predetermined data processing procedure is a software update of the mobile terminal in the communication network and / or a selection of a public land mobile network and / or a re-registration of the mobile terminal.

6. The method of claim 1 , wherein the communication service comprises the provision of one or more communication sessions to the mobile terminal.

7. Providing a communication service to the mobile terminal taking into consideration that the mobile terminal is temporarily unreachable from the communication network, maintaining one or more communication sessions established before the mobile terminal became temporarily unreachable; and providing said maintained communication session or sessions to said mobile terminal when said mobile terminal becomes reachable again.

8. Providing a communication service to the mobile terminal taking into consideration that the mobile terminal is temporarily unreachable from the communication network, commencing downlink buffering until the mobile terminal is reachable again; and c) commencing transmission of the buffered downlink when the mobile terminal becomes reachable again.

9. 2. The method of claim 1, wherein providing communication services to the mobile terminal considering that the mobile terminal is temporarily unreachable in the communication network comprises maintaining a mobility management context, a session management context, or both of the mobile terminal.

10. The method of claim 1 , further comprising the step of transmitting a mobility management context, a session management context, or both, to the mobile terminal when the mobile terminal is reachable again in the communications network.

11. A wireless communication system, comprising: a mobile terminal configured to detect that a communication network of the wireless communication system is temporarily unreachable by the mobile terminal executing a predetermined data processing procedure; a core network component of said communications network; the mobile terminal is configured to, in response to said detecting, transmit an indication to the core network component that the mobile terminal is temporarily unreachable in the communications network; the core network component is configured, in response to receiving the indication, to provide communication services to the mobile terminal, taking into account that the mobile terminal is temporarily unreachable in the communications network, to provide information to an application function regarding the period during which the communications network is temporarily unreachable, and to initiate a back-off timer due to unreachability. Wireless communication system.

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