Disaster condition indication of a serving plmn

Abstract

The invention relates to a new mechanism involving a network node (100) and a client device (300) for indicating that a serving PLMN (610) is in a disaster situation. The network node informs the client device by control signaling (510) that the client device's serving PLMN is in a disaster situation. Thereby, the client device can take appropriate measures to avoid service interruption, e.g. by initiating a PLMN selection procedure to register at a visited PLMN (620) not in a disaster situation. Examples of control signaling that can be used in this context are SIB, NAS, RRC messages or paging messages. Furthermore, the invention also relates to corresponding methods and computer programs.

Description

Technical Field

[0001] Embodiments of the present invention relate to network nodes and client devices for disaster status indication in a Public Land Mobile Network (PLMN) communication system. Furthermore, the present invention also relates to corresponding methods and computer programs. Background Technology

[0002] During disasters, cellular networks often become overloaded or unavailable, potentially denying users service. Disasters can be man-made, such as a building fire, or natural disasters, such as an earthquake. When a disaster occurs, many people may try to call each other or emergency services. As multiple users simultaneously request service, network resources can become congested, and users may be unable to obtain the requested service. Network outages can also occur during disasters, rendering the network unavailable. Summary of the Invention

[0003] The purpose of the embodiments of the present invention is to provide a solution to reduce or solve the disadvantages and problems of conventional solutions.

[0004] Another objective of embodiments of the present invention is to provide a disaster status indication mechanism for communication systems.

[0005] The above and other objectives are achieved through the various embodiments of this application.

[0006] According to a first aspect of the invention, the above and other objectives are achieved by a network node for a communication system, the network node being associated with a serving public land mobile network (PLMN) of a first client device, wherein the network node is used for:

[0007] When it is determined that the service PLMN of the first client device is in a disaster state, a first control message is sent to the first client device, wherein the first control message indicates that the service PLMN of the first client device is in a disaster state.

[0008] The association of a network node with a PLMN can be understood as the network node being a part of the PLMN.

[0009] The status of a PLMN in a disaster state can be determined by government agencies and may be attributed to natural disasters.

[0010] In some cases, a serving PLMN can be a home PLMN.

[0011] The advantage of the network node according to the first aspect is that it notifies the client device of the disaster status of the service PLMN so that the client device can, for example, move to another PLMN that is not in a disaster status to obtain service.

[0012] In one implementation of the network node according to the first aspect, the network node is the Access and Mobility Management Function (AMF) of the core network, wherein the first control message is a registration rejection message, a deregistration request message, a configuration update command message, or a service rejection message.

[0013] The advantage of this implementation is that the client device will know that the network node is still able to communicate with it. Therefore, the client device can proactively move to another PLMN that is not in a disaster state to obtain service.

[0014] In one implementation of the network node according to the first aspect, the network node is a network access node of a Radio Access Network (RAN), wherein the first control message is a paging message.

[0015] The advantage of this implementation is that, since the paging channel is monitored by all client devices and the paging message is received by all client devices, the disaster status of the serving PLMN can be notified to multiple client devices simultaneously.

[0016] In one implementation of the network node according to the first aspect, the network node is a network access node of the RAN, wherein the first control message is a radio resource control (RRC) connection rejection message, an RRC connection release message, or an RRC service PLMN disaster status message.

[0017] The advantage of this implementation is that instructions using RRC signaling can be more robust than, for example, instructions using NAS signaling.

[0018] In one implementation of the network node according to the first aspect, the network node is a network access node of the RAN, wherein the first control message is a system information block (SIB).

[0019] The advantage of this implementation is that client devices continuously monitor the SIB, meaning they will be directly informed of the disaster situation. Furthermore, because the SIB is broadcast, all client devices in the serving cell will be notified of the disaster situation of the serving PLMN.

[0020] In one implementation of the network node according to the first aspect, the network node is also used for:

[0021] When it is determined that the service PLMN of the first client device is in a disaster state, the first client device is redirected from the service PLMN to the access PLMN of the first client device.

[0022] The advantage of this implementation is that it allows client devices to resume service even without any service interruption.

[0023] In one implementation of the network node according to the first aspect, access to the PLMN belongs to a 3GPP or non-3GPP system.

[0024] The advantage of this implementation is that non-3GPP systems can provide services to client devices because they do not use the RAN of the 3GPP system, which is the most likely entity in the network to become congested during disasters.

[0025] In one implementation of the network node according to the first aspect, the first control message further instructs at least one timer that defines the start registration time of the first client device at the access PLMN and / or the re-registration time of the first client device at the service PLMN.

[0026] A timer defining the start registration time can also be understood as a timer defining the minimum waiting time before registration begins. Similarly, a timer defining the re-registration time can be understood as a timer defining the minimum waiting time before re-registration begins.

[0027] The advantage of this implementation is that the network will not be overloaded by too many client devices simultaneously attempting to register. Instead, registration can be distributed over a longer period of time. This also applies to the re-registration process to the service PLMN.

[0028] In one implementation of the network node according to the first aspect, the network node is also used for:

[0029] When it is determined that the service PLMN of the second client device is in a disaster state, a second control message is sent to the second client device, wherein the second control message indicates that the service PLMN of the second client device is in a disaster state.

[0030] The advantage of this implementation is that if the service PLMN becomes unresponsive, the client device will be able to obtain information about the disaster situation from other PLMNs that are still in operation.

[0031] In one implementation of the network node according to the first aspect, the network node is a network access node of the RAN, wherein the second control message is an SIB.

[0032] The advantage of this implementation is that the client device can obtain SIB information of other available PLMNs during the PLMN scanning process.

[0033] In one implementation of the network node according to the first aspect, the network node is also used for:

[0034] Upon determining that the disaster situation of the service PLMN of the second client device has ended, a third control message is sent to the second client device, wherein the third control message indicates that the disaster situation of the service PLMN of the second client device has ended.

[0035] The advantage of this implementation is that when the disaster situation has ended, the second client device can re-register with the service PLMN of the second client device.

[0036] According to a second aspect of the invention, the above and other objectives are achieved by a client device for a communication system, the client device being configured to be served by a serving PLMN, and further configured to:

[0037] Receive a first control message from a first network node associated with the serving PLMN of the client device, wherein the first control message indicates that the serving PLMN is in a disaster state; and / or

[0038] A second control message is received from a second network node associated with the access PLMN of the client device, wherein the second control message indicates that the service PLMN is in a disaster state.

[0039] The advantage of the second aspect for client devices lies in notifying them of the disaster status of the serving PLMN. This means that client devices can initiate a PLMN selection process to find another PLMN that is not in a disaster state. This avoids or minimizes service interruptions for client devices.

[0040] In one implementation of the client device according to the second aspect, the client device is further used for:

[0041] Obtain a list of PLMNs that include one or more access PLMNs; and

[0042] Upon receiving the first or second control message, register at the access PLMN in the PLMN list.

[0043] The advantage of this implementation is that, in the event of a disaster, the client device will know which PLMNs to register with.

[0044] In one implementation of the client device according to the second aspect, the first control message and / or the second control message further indicate at least one timer that defines the start registration time of the client device at the access PLMN and / or the re-registration time of the client device at the service PLMN.

[0045] A timer defining the start registration time can also be understood as a timer defining the minimum waiting time before registration begins. Similarly, a timer defining the re-registration time can be understood as a timer defining the minimum waiting time before re-registration begins.

[0046] The advantage of this implementation is that the network can configure client devices based on the minimum waiting time required to complete registration. This allows the network to prioritize some client devices over others for faster and more efficient registration.

[0047] In one implementation of the client device according to the second aspect, the first network node is the AMF of the core network, wherein the first control message is a registration rejection message, a deregistration request message, a configuration update command message, or a service rejection message.

[0048] The advantage of this implementation is that client devices can obtain information from the core network via NAS signaling even before the network becomes unresponsive, which may occur when the PLMN is in a disaster state.

[0049] In one implementation of the client device according to the second aspect, the first network node is a network access node of the RAN, and the first control message is a paging message.

[0050] The advantage of this implementation is that, since the paging channel is monitored by all client devices and the paging message is received by all client devices, the disaster status of the serving PLMN can be notified to multiple client devices simultaneously.

[0051] In one implementation of the client device according to the second aspect, the first network node is a network access node of the RAN, wherein the first control message is an RRC connection rejection message, an RRC connection release message, or an RRC service PLMN disaster status message.

[0052] The advantage of this implementation is that instructions using RRC signaling can be more robust than, for example, instructions using NAS signaling.

[0053] In one implementation of the client device according to the second aspect, the first network node is a network access node of the RAN, wherein the first control message is an SIB.

[0054] The advantage of this implementation is that client devices continuously monitor the SIB, meaning they will be directly informed of the disaster situation. Furthermore, because the SIB is broadcast, all client devices in the serving cell will be notified of the disaster situation of the serving PLMN.

[0055] In one implementation of the client device according to the second aspect, the second network node is a network access node of the RAN, and the second control message is an SIB.

[0056] The advantage of this implementation is that the client device can obtain SIB information of other available PLMNs during the PLMN scanning process.

[0057] In one implementation of the client device according to the second aspect, the client device is further used for:

[0058] A third control message is received from a second network node associated with the client device's access to the PLMN, indicating that the disaster situation of the client device's service PLMN has ended.

[0059] The advantage of this implementation is that client devices can re-register with the service PLMN once the disaster situation has ended.

[0060] According to a third aspect of the invention, the above and other objectives are achieved by a method for a network node associated with a serving PLMN of a first client device, the method comprising:

[0061] When it is determined that the service PLMN of the first client device is in a disaster state, a first control message is sent to the first client device, wherein the first control message indicates that the service PLMN of the first client device is in a disaster state.

[0062] The method according to the third aspect can be extended to an implementation corresponding to the implementation of the network node according to the first aspect. Therefore, the implementation of this method includes one or more features of the corresponding implementation of the network node.

[0063] The advantages of the method based on the third aspect are the same as the advantages of the corresponding implementation method of the network nodes based on the first aspect.

[0064] According to a fourth aspect of the invention, the above and other objectives are achieved by a method for a client device configured to be served by a serving PLMN, the method comprising:

[0065] Receive a first control message from a first network node associated with the serving PLMN of the client device, wherein the first control message indicates that the serving PLMN is in a disaster state; and / or

[0066] A second control message is received from a second network node associated with the access PLMN of the client device, wherein the second control message indicates that the service PLMN is in a disaster state.

[0067] The method according to the fourth aspect can be extended to an implementation corresponding to the implementation of the client device according to the second aspect. Therefore, the implementation of this method includes one or more features of the corresponding implementation of the client device.

[0068] The advantages of the method based on the fourth aspect are the same as the advantages of the corresponding implementation method of the client device based on the second aspect.

[0069] The present invention also relates to a computer program comprising program code that, when run by at least one processor, causes the at least one processor to perform any of the methods provided in embodiments of the present invention. Furthermore, the present invention relates to a computer program product comprising a computer-readable medium and the computer program therein, wherein the computer program is contained in the computer-readable medium, and the computer-readable medium comprises one or more of the following: read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), flash memory, electrically EPROM (EEPROM), and hard disk drive.

[0070] Other applications and advantages of embodiments of the present invention will become apparent from the following detailed description. Attached Figure Description

[0071] The accompanying drawings are intended to illustrate and explain different embodiments of the invention, in which:

[0072] – Figure 1 A network node according to an embodiment of the present invention is shown;

[0073] – Figure 2 This illustrates the control signaling from the network node to the client device;

[0074] – Figure 3 A method for a network node according to an embodiment of the present invention is shown;

[0075] – Figure 4 A client device according to an embodiment of the present invention is shown;

[0076] – Figure 5 The control signaling from the first and second network nodes to the client device is shown;

[0077] – Figure 6 A method for a client device according to an embodiment of the present invention is shown;

[0078] – Figure 7An example is shown where instructions regarding a disaster situation are carried or included in the SIB;

[0079] – Figure 8 and Figure 9 An example is shown when providing instructions about a disaster situation in NAS signaling;

[0080] – Figure 10 and Figure 11 An example is shown when providing instructions about a disaster situation in an RRC message; and

[0081] – Figure 12 An example is shown when providing information about a disaster situation during paging. Detailed Implementation

[0082] When a public land mobile network (PLMN) is unable to provide services such as voice calls or mobile data services to user equipment (UE) due to a disaster, there are usually other available PLMNs in the area that can provide services to the UE. However, these PLMNs may be configured as disabled PLMNs in the UE, so the UE will never select one of these PLMNs.

[0083] To minimize service disruptions, it is advantageous to enable a UE in a given PLMN to obtain service from another PLMN in areas experiencing disaster situations, even if that other PLMN is normally a banned PLMN for the UE. PLMN selection is the process that allows the UE to select the most suitable PLMN at a specific point in time. Most of the time, when the UE is in its home country, the home PLMN will be the most suitable PLMN, and therefore the home PLMN will be the serving PLMN. To prevent the UE from switching from its home PLMN, roaming is typically disabled within the home country. For example, other PLMNs in the home country can be added to the banned PLMN list so that the UE does not unnecessarily roam to these PLMNs.

[0084] Embodiments of the present invention provide a disaster status indication mechanism for a communication system, thereby notifying client devices such as UEs that the serving PLMN is in a disaster status. Therefore, the client devices can take appropriate measures, such as initiating a PLMN selection process.

[0085] Figure 1 A network node 100 according to an embodiment of the present invention is shown. Figure 1In the illustrated embodiment, network node 100 includes a processor 102, a transceiver 104, and a memory 106. The processor 102 can be coupled to the transceiver 104 and the memory 106 via a communication device 108 known in the art. Network node 100 may also include an antenna or antenna array 110 coupled to the transceiver 104, meaning that network node 100 can be configured for wireless communication in a wireless communication system. Network node 100 can be used to perform certain actions, which can be understood in this disclosure as network node 100 including suitable means for performing said actions, such as the processor 102 and the transceiver 104.

[0086] The processor 102 of network node 100 may be referred to as one or more general-purpose central processing units (CPUs), one or more digital signal processors (DSPs), one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), one or more programmable logic devices, one or more discrete gates, one or more transistor logic devices, one or more discrete hardware components, and one or more chipsets. The memory 106 of network node 100 may be read-only memory, random access memory, or non-volatile random access memory (NVRAM).

[0087] The transceiver 104 of network node 100 may be a transceiver circuit, a power controller, an antenna, or an interface for communicating with other modules or devices. In some embodiments, the transceiver 104 of network node 100 may be a separate chipset or may be integrated into a chipset with processor 102. In some embodiments, the processor 102, transceiver 104, and memory 106 of network node 100 are integrated into a single chipset.

[0088] refer to Figure 1 and Figure 2 According to an embodiment of the present invention, network node 100 is associated with the service PLMN 610 of the first client device 300. Network node 100 is configured to: send a first control message 510 to the first client device 300 when it is determined that the service PLMN 610 of the first client device 300 is in a disaster state. The first control message 510 indicates that the service PLMN 610 of the first client device 300 is in a disaster state.

[0089] Figure 3This shows that it can be done in network node 100, for example in Figure 1 The flowchart illustrates the corresponding method 200 executed in the network node shown. Method 200 for a network node 100 associated with a service PLMN 610 of a first client device 300 includes: sending a first control message 510 to the first client device 300 when it is determined that the service PLMN 610 of the first client device 300 is in a disaster condition. The first control message 510 indicates that the service PLMN 610 of the first client device 300 is in a disaster condition.

[0090] In previous embodiments of the present invention, network node 100 is associated with the serving PLMN of the client device. This can be understood as network node 100 being part of the serving PLMN, such as a base station or core network function of the RAN. However, this solution can also address situations where network node 100 is not associated with the serving PLMN of the client device. Therefore, in embodiments of the present invention, network node 100 is further configured to: send a second control message 520 to the second client device when it is determined that the serving PLMN of the second client device is in a disaster state. The second control message 520 indicates that the serving PLMN of the second client device is in a disaster state. This also... Figure 5 As shown, network node 100 sends a second control message 520 to the client device. Therefore, even when the client device's serving PLMN stops, the client device can be notified of the disaster status of its serving PLMN. In this case, network node 100 can be a network access node of the RAN, and the second control message 520 can be an SIB. In embodiments of the invention, the second control message 520 can also indicate the identity (ID) of the serving PLMN so that the client device can easily identify the serving PLMN.

[0091] Figure 4 A client device 300 according to an embodiment of the present invention is shown. Figure 4 In the illustrated embodiment, client device 300 includes a processor 302, a transceiver 304, and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 via a communication means 308 known in the art. Client device 300 can be used for wireless and wired communication in both wireless and wired communication systems. Wireless communication capability is provided using an antenna or antenna array 310 coupled to transceiver 304, while wired communication capability is provided using a wired communication interface 312 coupled to transceiver 304. Client device 300 is used to perform certain actions, which can be understood in this disclosure as client device 300 including suitable means for performing said actions, such as the processor 302 and transceiver 304.

[0092] The processor 302 of the client device 300 may be referred to as one or more general-purpose CPUs, one or more DSPs, one or more ASICs, one or more FPGAs, one or more programmable logic devices, one or more discrete gates, one or more transistor logic devices, one or more discrete hardware components, and one or more chipsets. The memory 306 of the client device 300 may be read-only memory, random access memory, or NVRAM.

[0093] The transceiver 304 of the client device 300 may be a transceiver circuit, a power controller, an antenna, or an interface for communicating with other modules or devices. In some embodiments, the transceiver 304 of the client device 300 may be a separate chipset or may be integrated into a chipset with the processor 302. In some embodiments, the processor 302, transceiver 304, and memory 306 of the client device 300 are integrated into a single chipset.

[0094] refer to Figure 4 and Figure 5 According to an embodiment of the present invention, the client device 300 configured to be served by the service PLMN 610 is further configured to: receive a first control message 510 from a first network node 100 associated with the service PLMN 610 of the client device 300, wherein the first control message 510 indicates that the service PLMN 610 is in a disaster state; and / or receive a second control message 520 from a second network node 100' associated with the access PLMN 620 of the client device 300, wherein the second control message 520 indicates that the service PLMN 610 is in a disaster state.

[0095] In an embodiment of the present invention, the second network node 100' may be a network access node of the RAN, and the second control message 520 is an SIB broadcast by the second network node 100'.

[0096] It should be noted that the client device 300 may receive only the first control message 510, only the second control message 520, or both the first control message 510 and the second control message 520.

[0097] Figure 6 This shows that it can be implemented in client device 300, for example in Figure 4The flowchart illustrates the corresponding method 400 executed in the client device. The client device 300 is configured to be served by a serving PLMN 610. Method 400 includes: receiving a first control message 510 402 from a first network node 100 associated with the serving PLMN 610 of the client device 300, wherein the first control message 510 indicates that the serving PLMN 610 is in a disaster state; and / or receiving a second control message 520 404 from a second network node 100' associated with an access PLMN 620 of the client device 300, wherein the second control message 520 indicates that the serving PLMN 610 is in a disaster state.

[0098] When client device 300 is notified or learns that service PLMN 610 is in a disaster state, client device 300 can attempt to register with another PLMN that is not in a disaster state. This avoids or shortens service interruption for client device 300. Therefore, in embodiments of the present invention, client device 300 is used to obtain a list of PLMNs including one or more access PLMNs. Client device 300 is also used to: register with the access PLMN in the PLMN list upon receiving a first control message 510 from a first network node 100 or a second control message 520 from a second network node 100'.

[0099] Client device 300 has many different ways to obtain the list of PLMNs. A non-limiting example could be any of the following:

[0100] ● Obtain the PLMN list from the control message indicating the PLMN list sent by the network node. The control message may be part of a non-access stratum (NAS) protocol and may be, for example, a configuration update command message, a registration accept message, a registration reject message, a service accept message, a service reject message, and a deregistration request message;

[0101] ● Obtain the PLMN list from the subscriber identity module (SIM) configuration of the client device; and

[0102] ● Obtain the list of PLMNs from the mobile equipment (ME) configuration of the client device.

[0103] In embodiments of the present invention, the PLMN list includes the identity of each PLMN in the PLMN list so that the PLMN can be identified by the client device / UE.

[0104] For registration synchronization and resource control in communication system 500, the first control message 510 and / or the second control message 520 may also instruct at least one timer T, which defines the start registration time of the first client device 300 at the access PLMN 620 and / or the re-registration time of the first client device 300 at the service PLMN 610. The timer defining the start registration time can also be understood as a timer defining the minimum waiting time for starting registration at the access PLMN. The timer defining the re-registration time can also be understood as a timer defining the minimum waiting time for starting re-registration at a previous service PLMN that was in a disaster state in the past.

[0105] In the following disclosure, further exemplary implementations of this solution will be described. This mechanism for indicating a disaster situation can be implemented using different types of control signaling and involving one or more communication processes. These implementations are set entirely or partially within a 3GPP context, and therefore terminology and system architecture are used herein, but embodiments of the invention are not limited thereto. Furthermore, network nodes can determine that the serving PLMN is in a disaster situation in a variety of different ways, which is outside the scope of this disclosure. However, it may be mentioned that network node 100 or the network may be notified by government agencies, operators, etc.

[0106] Figure 7 This illustrates carrying or including an indication of a disaster situation in the system information of the serving PLMN. When a UE (corresponding to a client device) is served by a PLMN in a disaster situation and the serving PLMN enters a disaster situation, the serving PLMN in the disaster situation broadcasts an indication of its disaster situation in the system information. Therefore, the RAN's network access node 100 can broadcast the new indication in the SIB as a first control message 510 to one or more UEs (however, Figure 7 (Only one UE is shown). Network access node 100 can be, for example, a gNB serving the PLMN.

[0107] also, Figure 8 and Figure 9 This illustrates a scenario where an indication of a disaster situation is provided in Non-Access Stratum (NAS) signaling. In these embodiments, network node 100 may be the Access and Mobility Management Function (AMF) of the core network.

[0108] Regarding the service request process, Figure 8 In step I, the UE is served by a PLMN in a disaster state. The UE executes the service request by sending a service request message to the AMF associated with the UE's serving PLMN. Figure 8 In step II, because the service PLMN is already in a disaster state, the AMF rejects the service request; Figure 8In step III, the AMF rejects the service request by sending a service rejection message to the UE as a first control message 510 indicating that the serving PLMN is in a disastrous state. In this regard, the service rejection message may include a new cause value indicating that the serving PLMN is in a disastrous state. Figure 8 In step IV, the UE receives a service rejection message from the AMF and can, for example, perform a PLMN selection procedure to search for a PLMN that is not in a disaster state. In this regard, a list of PLMNs that includes one or more access PLMNs can be used.

[0109] Accordingly, for the registration request process, in Figure 8 In step I, the UE is served by the PLMN in a disaster state and performs a registration request by sending a registration request message to the AMF. Figure 8 In step II, the AMF rejects the registration request because the serving PLMN is in a disaster state; in step III, the AMF sends a registration rejection message to the UE as a first control message 510, rejecting the registration request. The registration rejection message may include a new reason value indicating that the serving PLMN is in a disaster state. Figure 8 In step IV, the UE can perform the PLMN selection process as described above when it receives a registration rejection message.

[0110] exist Figure 9 In this process, the AMF initiates the deregistration procedure by sending a deregistration request message with a new cause value to redirect the UE to another PLMN that is not in a disaster state. Therefore, in Figure 9 In step I, the serving PLMN in a disaster state sends a deregistration request message to the UE via the AMF as a first control message 510 to execute the deregistration request. The deregistration request message may include a new reason value indicating that the serving PLMN is in a disaster state.

[0111] The network can also initiate a configuration update command process by sending a configuration update command message to the UE with a new indication that the serving PLMN is in a disaster state and the UE needs to move to another PLMN that is not in a disaster state. Therefore, in Figure 9 In step I, the serving PLMN in a disaster state sends a configuration update command message to the UE via the AMF as the first control message 510 to execute the configuration update command process.

[0112] In both cases, Figure 9 In step II, the UE can initiate the PLMN selection process as described above when it receives a deregistration request message or a configuration update command message.

[0113] Under normal circumstances, the UE may perform a NAS signaling procedure and receive no response from the serving PLMN, for example, due to a lack of available radio resources. In this situation, the UE may perform a scan of neighboring PLMNs to see if their SIBs indicate that the serving PLMN is in a disaster state. This is more or less related to Figure 5 Consistent with the embodiments shown, in which accessing the PLMN uses a second control message 520 to notify the UE that their serving PLMN is in a disaster state.

[0114] also, Figure 10 and Figure 11 This illustrates, for example, when by a RAN node (in Figure 10 This is denoted as "RN" in the context of situations such as when gNB provides instructions about a disaster situation in an RRC message.

[0115] Figure 10 This illustrates two different scenarios where RRC messages are used to indicate a disaster situation. Establishing an RRC connection is the first step for the UE to enter connected mode. NAS messages can only be sent after the UE is in connected mode. Typically, during a disaster, RAN resources become congested, and the network may reject RRC connection establishment messages. Therefore, by adding a current indication to the RRC message, the network can be notified of the disaster situation of the serving PLMN even if the RRC connection fails. Thus, using RRC signaling generally provides more robust control signaling.

[0116] exist Figure 10 In the first scenario, an RRC rejection message with disaster indication and redirection information is used. When the UE attempts to establish or restore an RRC connection, the serving RAN node can reject the RRC connection and... Figure 10 In step I, an RRC connection rejection message is sent to the UE as the first control message 510. The RRC connection rejection message includes an indication that the serving PLMN is in a disaster state, and may also include redirection information to redirect the UE to a cell of another PLMN that is not in a disaster state.

[0117] Therefore, in embodiments of the present invention, network node 100 can be used to redirect client device 300 from service PLMN 610 to access PLMN 620 when it is determined that client device 300's service PLMN 610 is in a disaster state. In this regard, the aforementioned PLMN list can be used for disaster state PLMN selection. Furthermore, the aforementioned timer T can be used to inform the client device when to register or re-register.

[0118] Access to PLMN 620 can be to either a 3GPP or non-3GPP system. Generally, there may be two different access systems, meaning the UE has two ways to access the core network. One can be 3GPP, such as GSM, WCDMA, LTE, NR; the other can be non-3GPP, such as via WiFi. Therefore, a UE can move from a 3GPP system to a non-3GPP system, and vice versa.

[0119] exist Figure 10 In the second scenario, an RRC release message can be used instead. When the UE attempts to resume the RRC connection, the serving RAN node can release the RRC connection and... Figure 10 In step I, an RRC connection release message is sent to the UE as the first control message 510. The RRC connection release message indicates that the serving PLMN is in a disaster state and may also indicate redirection information.

[0120] for Figure 10 In either of the two scenarios described above, the UE can initiate the PLMN selection process as described above in step II upon receiving an RRC connection rejection message or an RRC connection release message.

[0121] Figure 11 An example is shown where a new RRC message type is alternatively used, which could be labeled, for example, as an RRC serving PLMN disaster condition message or any other suitable label. Therefore, when a UE attempts to establish or restore an RRC connection, the serving RAN node can use the new RRC message type as a response message, such as... Figure 11 As shown. In step I, the UE sends an RRC connection message to the serving RAN node. In step II, the serving RAN node rejects the RRC connection message, and in step III, the serving RAN node sends a new RRC message type to the UE as a response message. Upon receiving the new RRC message type, the UE can initiate a PLMN selection procedure in step IV. However, the new RRC message type can also be an independent message type, rather than... Figure 11 The response message type is shown. This means that the UE does not need to send a request message. Therefore, by using the new RRC message type, the UE is notified that the serving PLMN is in a disaster state, and the UE can be redirected to a cell belonging to one or more other PLMNs that are not in a disaster state.

[0122] at last, Figure 12This illustrates the provision of information about a disaster situation during paging. Typically, a UE performs a PLMN scan to find an available PLMN, meaning the UE must read the broadcast SIB. The serving PLMN or serving RAN node can page a UE to notify it of a disaster situation. Therefore, the serving RAN node can send a paging message as a first control message 510 indicating that the serving PLMN is in a disaster situation. The paging channel is monitored by all UEs, and the paging message is received by all UEs, thus multiple UEs can be reached through the paging message.

[0123] Furthermore, embodiments of the present invention also involve an additional mechanism for notifying client device 300 that the disaster status of its service PLMN has ended.

[0124] From the perspective of the network node, network node 100 can also be used to send a third control message 530 to client device 300 after determining that the disaster situation of the service PLMN of client device 300 has ended. Therefore, the third control message 530 indicates that the disaster situation of the service PLMN of client device 300 has ended. This is in Figure 5 As shown in the diagram, where the network node represented here as the second network node 100' sends the third control message 530 to the client device 300.

[0125] From the perspective of client device 300 and for further reference Figure 5 The client device 300 can also receive a third control message 530 from a second network node 100' associated with the access PLMN 620. The third control message 530 indicates that the disaster situation of the service PLMN 610 has ended. Therefore, after the disaster situation has ended, the client device 300 can attempt to re-register with the service PLMN 610.

[0126] The signaling of the third control message 530 can be executed using the same or corresponding method as the signaling used for the first control message 510. Therefore, the third control message 530 can be:

[0127] ● Registration rejection messages, deregistration request messages, configuration update command messages, or service rejection messages sent by AMF;

[0128] ● Paging messages sent by RAN nodes;

[0129] ● RRC connection rejection message, RRC connection release message, or RRC service PLMN disaster status message sent by the RAN node;

[0130] ● SIBs sent by the RAN node.

[0131] Embodiments of this invention can be implemented using different communication standards. For example, this approach may affect 3GPP TS24.501 and TS 23.122–NAS. The proposed changes may affect NR RRC specifications, such as 38.331. For example, the sections on "System information acquisition," "RRC Connection Reject," and "RRC Connection Release." Furthermore, new information elements (IEs) can be added to the "RRCReject" and "RRCRelease" messages. New 5G mobility management (5GMM) reason values ​​indicating disaster conditions can, for example, be added to Table 9.11.3.2.1 in 3GPP TS 24.501, exemplified here in bold underlined text as "Disaster Condition."

[0132] Table 9.11.3.2.1: 5GMM Cause Information Elements

[0133]

[0134]

[0135] The network node 100 disclosed herein includes, but is not limited to: NodeB in a wideband code division multiple access (WCDMA) system, an evolved NodeB (eNB) or an evolved NodeB (eNodeB) in an LTE system, or a relay node or access point, or vehicle-mounted equipment, wearable devices, or a gNB in ​​a fifth-generation (5G) network.

[0136] Furthermore, network node 100 here can be represented as a wireless network access node, access network access node, access point, or base station. For example, in some networks it may be referred to as a radio base station (RBS), "gNB," "gNodeB," "eNB," "eNodeB," "NodeB," or "B node," depending on the technology and terminology used. Based on transmission power and thus also on cell size, wireless network access nodes can have different categories, such as macro eNodeB, home eNodeB, or pico base station. A wireless network access node can be a station (STA), which is any device including MAC and PHY interfaces compliant with IEEE 802.11 connected to the wireless media. A wireless network access node can also be a base station corresponding to a 5G wireless system.

[0137] However, network node 100 can also be a core network node. Network node 100 can be, for example, an AMF as described above, but it can also be a session management function (SMF) or a policy control function (PCF).

[0138] The client device 300 in this disclosure includes, but is not limited to: UE, such as smartphones, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) sites, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to a wireless modem, in-vehicle devices, wearable devices, integrated access and backhaul (IAB) nodes such as mobile cars or devices installed in cars, drones, device-to-device (D2D) devices, wireless cameras, mobile sites, access terminals, user units, wireless communication devices, wireless local access network (WLAN) sites, wireless-enabled tablets, laptop embedded devices, universal serial bus (USB) adapters, customer-premises equipment (CPE) and / or chipsets. In the Internet of Things (IoT) scenario, client device 300 can represent a machine or other device or chipset that performs communication with another wireless device and / or network device.

[0139] The UE can also be referred to as a mobile phone, cellular phone, wirelessly-enabled computer tablet, or laptop. In this context, the UE can be, for example, a portable, pocket-sized, handheld, computer-configurable, or vehicle-mounted mobile device capable of transmitting voice and / or data with another entity (e.g., another receiver or server) via a radio access network. The UE can be a site (STA), which is any device including IEEE 802.11-compliant media access control (MAC) and physical layer (PHY) interfaces connected to wireless medium (WM). The UE can also be used for communication in 3GPP-related LTE and Advanced LTE, WiMAX and its evolutions, and fifth-generation wireless technologies such as NR.

[0140] Furthermore, any method according to embodiments of the present invention can be implemented in a computer program having code means, which, when run by a processing means, causes the processing means to perform the steps of the method. The computer program is included in a computer-readable medium of the computer program product. The computer-readable medium can substantially include any memory, such as read-only memory (ROM), programmable read-only memory (PROM), erasable PROM (EPROM), flash memory, electrically erasable PROM (EEPROM), or hard disk drive.

[0141] Furthermore, those skilled in the art will recognize that embodiments of network node 100 and client device 300 include the necessary communication capabilities in the form of functions, devices, units, elements, etc., for executing the scheme. Examples of other such devices, units, elements, and functions include: processors, memories, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selection units, switches, interleavers, deinterleavers, modulators, modems, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoders, TCM decoders, power supply units, power feeders, communication interfaces, communication protocols, etc., which are suitably arranged together to execute the scheme.

[0142] Specifically, the processors of network node 100 and client device 300 may include one or more instances of, for example, a central processing unit (CPU), processing unit, processing circuitry, processor, application-specific integrated circuit (ASIC), microprocessor, or other processing logic capable of interpreting and executing instructions. Therefore, the term "processor" can refer to a processing circuitry system that includes multiple processing circuits (such as any, some, or all of the processing circuits described above). The processing circuitry system can also perform data processing functions for inputting, outputting, and processing data, including data buffering and device control functions such as call processing control, user interface control, etc.

[0143] Finally, it should be understood that the present invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1. A network node (100) for a communication system (500), comprising a processor (102) and a transceiver (104), characterized in that, The network node (100) is part of the serving public land mobile network (610) of the first client device (300), wherein the processor (102) is used for: When it is determined that the service PLMN (610) of the first client device (300) is in a disaster state, the transceiver (104) is controlled to send a first control message (510) to the first client device (300), wherein the first control message (510) indicates that the service PLMN (610) of the first client device (300) is in the disaster state. The network node (100) is the access and mobility management function (AMF) of the core network, wherein the first control message (510) is a registration rejection message, a deregistration request message, a configuration update command message, or a service rejection message; The processor (102) is also used for: When it is determined that the service PLMN (610) of the first client device (300) is in a disaster state, the first client device (300) is redirected from the service PLMN (610) to the access PLMN (620) of the first client device (300). The first control message (510) further indicates at least one timer (T), which defines the start registration time of the first client device (300) at the access PLMN (620) and / or the re-registration time of the first client device (300) at the service PLMN (610).

2. The network node (100) according to claim 1, characterized in that, The access PLMN (620) belongs to a 3GPP or non-3GPP system.

3. The network node (100) according to claim 1 or 2, characterized in that, The processor (102) is also used for: When it is determined that the service PLMN (610') of the second client device (300') is in a disaster state, the transceiver (104) is controlled to send a second control message (520) to the second client device (300'), wherein the second control message (520) indicates that the service PLMN (610') of the second client device (300') is in the disaster state.

4. The network node (100) according to claim 3, characterized in that, The network node (100) is a network access node of the RAN, wherein the second control message (520) is an SIB.

5. The network node (100) according to claim 1 or 2, characterized in that, The processor (102) is also used for: Upon determining that the disaster condition of the service PLMN (610') of the second client device (300') has ended, the transceiver (104) is controlled to send a third control message (530) to the second client device (300'), wherein the third control message (530) indicates that the disaster condition of the service PLMN (610') of the second client device (300') has ended.

6. A client device (300) for a communication system (500), comprising a processor (302) and a transceiver (304), characterized in that, The client device (300) is configured to be served by a service PLMN (610), and the processor (302) is used for: The transceiver (304) is controlled to receive a first control message (510) from a first network node (100), wherein the first control message (510) indicates that the service PLMN (610) is in a disaster state; the first network node (100) is part of the service PLMN (610) of the client device (300); The first network node (100) is the access and mobility management function (AMF) of the core network, wherein the first control message (510) is a registration rejection message, a deregistration request message, a configuration update command message, or a service rejection message; The processor (302) is also used for: The transceiver (304) is controlled to obtain a list of PLMNs including one or more access PLMNs; and Upon receiving the first control message (510), register at the access PLMN (620) in the PLMN list; The first control message (510) also indicates at least one timer (T), which defines the start registration time of the client device (300) at the access PLMN (620) and / or the re-registration time of the client device (300) at the service PLMN (610).

7. The client device (300) according to claim 6, characterized in that, The processor (302) is also used for: The transceiver (304) is controlled to receive a second control message (520) from a second network node (100') associated with the access PLMN (620) of the client device (300), wherein the second control message (520) indicates that the service PLMN (610) is in the disaster state.

8. The client device (300) according to claim 7, characterized in that, The processor (302) is also used for: Upon receiving the second control message (520), registration is performed at the access PLMN in the PLMN list.

9. The client device (300) according to claim 8, characterized in that, The first control message (510) and / or the second control message (520) also indicate at least one timer (T) that defines the start registration time of the client device (300) at the access PLMN (620) and / or the re-registration time of the client device (300) at the service PLMN (610).

10. The client device (300) according to any one of claims 7-9, characterized in that, The second network node (100') is the network access node of the RAN, wherein the second control message (520) is an SIB.

11. The client device (300) according to any one of claims 7-9, characterized in that, The processor (302) is also used for: The transceiver (304) is controlled to receive a third control message (530) from a second network node (100') associated with the access PLMN (620) of the client device (300), wherein the third control message (530) indicates that the disaster condition of the service PLMN (610) of the client device (300) has ended.

12. A method for a network node (100), characterized in that, The network node (100) is part of the serving PLMN (610) of the first client device (300), and the method includes: When it is determined that the service PLMN (610) of the first client device (300) is in a disaster state, a first control message (510) is sent to the first client device (300), wherein the first control message (510) indicates that the service PLMN (610) of the first client device (300) is in the disaster state; The network node (100) is the access and mobility management function (AMF) of the core network, wherein the first control message (510) is a registration rejection message, a deregistration request message, a configuration update command message, or a service rejection message; The method further includes: When it is determined that the service PLMN (610) of the first client device (300) is in a disaster state, the first client device (300) is redirected from the service PLMN (610) to the access PLMN (620) of the first client device (300). The first control message (510) further indicates at least one timer (T), which defines the start registration time of the first client device (300) at the access PLMN (620) and / or the re-registration time of the first client device (300) at the service PLMN (610).

13. A method for a client device (300), characterized in that, The client device (300) is configured to be served by a service PLMN (610), and the method includes: A first control message (510) is received from a first network node (100), wherein the first control message (510) indicates that the service PLMN (610) is in a disaster state; the first network node (100) is part of the service PLMN (610) of the client device (300); The first network node (100) is the access and mobility management function (AMF) of the core network, wherein the first control message (510) is a registration rejection message, a deregistration request message, a configuration update command message, or a service rejection message; The method further includes: Obtain a list of PLMNs that include one or more access PLMNs; and Upon receiving the first control message (510), register at the access PLMN (620) in the PLMN list; The first control message (510) also indicates at least one timer (T), which defines the start registration time of the client device (300) at the access PLMN (620) and / or the re-registration time of the client device (300) at the service PLMN (610).

14. The method according to claim 13, characterized in that, The method further includes: A second control message (520) is received from a second network node (100') associated with the access PLMN (620) of the client device (300), wherein the second control message (520) indicates that the service PLMN (610) is in the disaster state.

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