Support for roaming ues under disaster conditions

Abstract

An apparatus configured to process, based on signaling from a network, parameters related to roaming to an Evolved Packet System (EPS) when a Fifth Generation System (5GS) is in a disaster condition, wherein a subscriber to a Public Land Mobile Network (PLMN) provider operating the 5GS has a 5G only roaming agreement with a PLMN operating the EPS, determine the 5GS is in the disaster condition and generate, for transmission to the EPS, an attach request to attach to the EPS during the disaster condition.

Description

Support for Roaming UEs under Disaster ConditionsInventors: Vivek G Gupta, Haijing Hu and Sridhar PrakasamBackground

[0001] A user equipment (UE) may connect to a network that supports minimization of service interruption (MINT) . MINT provides a framework that enables the UE of a given Public Land Mobile Network (PLMN) to obtain disaster roaming services from another PLMN during a disaster condition. This provides the UEs with an opportunity to mitigate service interruptions and failures in the event of a disaster.Summary

[0002] Some example embodiments are related to an apparatus having processing circuitry configured to process, based on signaling from a network, parameters related to roaming to an Evolved Packet System (EPS) when a Fifth Generation System (5GS) is in a disaster condition, wherein a subscriber to a Public Land Mobile Network (PLMN) provider operating the 5GS has a 5G only roaming agreement with a PLMN operating the EPS, determine the 5GS is in the disaster condition and generate, for transmission to the EPS, an attach request to attach to the EPS during the disaster condition.

[0003] Other example embodiments are related to a Mobility Management Entity (MME) of an Evolved Packet System (EPS) configured to determine a Fifth Generation System (5GS) is in a disaster condition, determine the EPS provides support for roaming for a subscriber of the 5GS in the disaster condition, wherein the EPS does not support roaming for the subscriber in non-disaster conditions and generate, for broadcast by the EPS,an indication of the disaster condition and support of roaming for the 5GS in the disaster condition.Brief Description of the Drawings

[0004] Fig. 1 shows an example network arrangement according to various example embodiments.

[0005] Fig. 2 shows an example user equipment (UE) according to various example embodiments.

[0006] Fig. 3 shows an example base station according to various example embodiments.

[0007] Fig. 4 shows an example call flow for a UE in a disaster condition according to various example embodiments.

[0008] Fig. 5 shows an example of an Evolved Packet System (EPS) attach request message contents according to various example embodiments.

[0009] Fig. 6 shows an example of an EPS attach type information element (IE) according to various example embodiments .

[0010] Fig. 7 shows an example of a UE network capability IE according to various example embodiments.

[0011] Fig. 8 shows an example of an EPS attach accept message contents according to various example embodiments.

[0012] Fig. 9 shows an example of an EPS attach result IE according to various example embodiments.

[0013] Fig. 10 shows an example of an EPS Tracking AreaUpdate (TAU) request message contents according to various example embodiments.

[0014] Fig. 11 shows an example of an EPS update type IE according to various example embodiments.

[0015] Fig. 12 shows an example of an EPS TAU accept message contents according to various example embodiments.

[0016] Fig. 13 shows an example of an EPS update result IE according to various example embodiments.Detailed Description

[0017] The example embodiments may be further understood with reference to the following description and the related appended drawings, wherein like elements are provided with the same reference numerals. The example embodiments relate to a 5G-only roaming UE registering for a disaster roaming service in an Evolved Packet System (EPS) of a Visited Public Land Mobile Network (VPLMN) .

[0018] The example embodiments are described with regard to a UE . However, reference to a UE is merely provided for illustrative purposes. The example embodiments may be utilized with any electronic component that may establish a connection to an accessory device and is configured with the hardware, software, and / or firmware to exchange information and data withaccessory devices. Therefore, the UE as described herein is used to represent any electronic component.

[0019] The example embodiments are described with reference to various message contents and information elements (IES) , e.g., Figs. 5-13. When describing these message contents and IEs, the description is limited to the content or fields that are relevant to the roaming UE registering for a disaster roaming service in an EPS, e.g., those contents or fields that are new or have new values for registering for a disaster roaming service in an EPS. The other contents or fields may be considered to be the standard contents or fields defined in 3GPP Technical Specifications (TS) .

[0020] The exemplary embodiments are also described with regard to a fifth generation (5G) network that supports MINT. Generally, MINT refers to a framework that enables UEs to obtain disaster roaming services from a public land mobile network (PLMN) during a disaster condition. For instance, a PLMN may be unable to provide service in the event of a disaster, e.g. , natural disasters, fires, explosions, transportation accidents, etc. MINT may enable UEs of a given PLMN to obtain connectivity service (e.g. , voice call, mobile data service, etc. ) from another PLMN when the disaster condition applies. Thus, UEs may have the opportunity to mitigate service interruptions and failures in the event of a disaster. Throughout this description, a UE that cannot get service from a PLMN that it would normally be served by due to failure of service during a disaster condition and that is able to register with other PLMNs may be referred to as a "disaster inbound roamer." However, the example embodiments may also be implemented in other types ofnetworks, including but not limited to LTE networks, future evolutions of the cellular protocol (e.g., 5G-advanced networks, 6G networks, etc.) , or any other type of network.

[0021] A disaster condition may be initiated and terminated by a government or any other appropriate entity. The disaster condition may be applicable to a particular geographical region for a particular duration of time. Throughout this description, the disaster condition may be characterized as applying to a UE, a particular geographical region and / or PLMN. To differentiate between different types of PLMNs, reference is made to a PLMN with disaster condition and a PLMN without disaster condition. The term "PLMN with disaster condition" identifies a PLMN to which a disaster condition applies and the term "PLMN without disaster condition" identifies a PLMN that is not subject to a disaster condition. The PLMN without disaster condition may offer disaster roaming services to UEs of a PLMN with disaster condition, e.g., disaster inbound roamers. However, a PLMN without disaster condition is not required to offer disaster roaming services.

[0022] As indicated above, when the disaster condition applies, UEs may have the opportunity to mitigate service interruptions and failures. To provide an example, the UE may have no coverage of its home PLMN (HPLMN) and obtain information that a disaster conditions applies to the HPLMN. The UE may then register with another PLMN offering disaster roaming services within the region where the disaster condition applies. When the disaster condition ends and is no longer applicable to the HPLMN, the currently camped PLMN may stop offering disaster roaming services. The UE may then perform network re-selection / re-registration to return to its HPLMN. This example is merely provided for illustrative purposes. The exemplary embodiments do not require a HPLMN to be subject to a disaster condition and may be used with any appropriate type of PLMN with disaster condition.

[0023] Disaster roaming generally refers to a third generation partnership program (3GPP) roaming policy that applies during a disaster condition. MINT provides a framework to facilitate disaster roaming which may include operations on the UE side and / or network side that may not be permitted when a disaster condition is not present. To provide an example, a 5G- only national roaming UE may not normally access a roaming EPS (e.g., 4G system) . However, the example embodiments allow such a UE to register for a Disaster Roaming service in a roaming EPS when the 5G network of an HPLMN or VPLMN is in a disaster condition .

[0024] Since a 5G only roaming UE is not normally allowed to register with an EPS of the VPLMN, the example embodiments address various issues associated with a 5G only roaming UE registering with an EPS. Some example embodiments provide operations for network selection to support disaster roaming with EPS, SI non-access stratum (NAS) signaling to support disaster roaming with EPS, the behavior of 5G-only national roaming UEs regarding how to register with the Evolved Packet Core (EPC) of the VPLMN to resume 4G connectivity service when the disaster condition applies to the 5G VPLMN and the network behavior regarding how to enable the support of providing disaster roaming service in EPS. Each of these example embodiments will be described in greater detail below.

[0025] Fig. 1 shows an example network arrangement 100 according to various example embodiments. The example network arrangement 100 includes a UE 110. The UE 110 may be any type of electronic component that is configured to communicate via a network, e.g. , mobile phones, tablet computers, desktop computers, smartphones, embedded devices, wearables, Internet of Things (loT) devices, etc. An actual network arrangement may include any number of UEs being used by any number of users. Thus, the example of one UE 110 is merely provided for illustrative purposes.

[0026] The UE 110 may be configured to communicate with one or more networks. In the example of the network arrangement 100, the networks with which the UE 110 may wirelessly communicate are a 5G NR radio access network (RAN) 120 and a Long Term Evolution (LTE) RAN 122. The UE 110 may also communicate with other types of networks (e.g. , 5G cloud RAN, a next generation RAN (NG-RAN) , a legacy cellular network, etc. ) and the UE 110 may also communicate with networks over a wired connection. With regard to the example embodiments, the UE 110 may establish a connection with the 5G NR RAN 120 and the LTE RAN 122. Therefore, the UE 110 may have a 5G NR chipset to communicate with the NR RAN 120 and an LTE chipset to communicate with the LTE RAN 122.

[0027] The 5G NR RAN 120 and the LTE RAN 122 may be portions of a cellular network that may be deployed by a network carrier (e.g., Verizon, AT&T, T-Mobile, etc. ) . The 5G NR RAN 120 and the LTE RAN 122 may include cells or base stations that are configured to send and receive traffic from UEs that areequipped with the appropriate cellular chip set. In this example, the 5G NR RAN 120 includes the gNB 120A and the LTE RAN 122 includes the eNB 122A. However, reference to a gNB and eNB is merely provided for illustrative purposes, any appropriate base station or cell may be deployed (e.g. , Node Bs, eNodeBs, HeNBs, eNBs, gNBs, gNodeBs, macrocells, microcells, small cells, femtocells, etc. ) .

[0028] Any association (or registration) procedure may be performed for the UE 110 to connect to the 5G NR RAN 120 or LTE RAN 122. For example, as discussed above, the 5G NR RAN 120 may be associated with a particular network carrier where the UE 110 and / or the user thereof has a contract and credential information (e.g. , stored on a SIM card) . Upon detecting the presence of the 5G NR RAN 120, the UE 110 may transmit the corresponding credential information to associate with the 5G NR RAN 120. More specifically, the UE 110 may associate with a specific cell (e.g. , gNB 120A) .

[0029] In the example embodiments, the 5G NR RAN 120 may be operated by the Public Land Mobile Network (PLMN) provider with which the user has a subscription, e.g., the home PLMN (HPLMN) . In some example embodiments, the 5G NR RAN 120 may also be a visited PLMN (VPLMN) where the provider of the HPLMN has a roaming agreement with the provider of the VPLMN allowing the UE 110 to access 5G services from the VPLMN. The LTE RAN 122 is provided by a VPLMN provider that may be the same VPLMN provider as providing the 5G NR RAN 120 or a different VPLMN provider. In the example embodiments, the HPLMN provider does not have an LTE (e.g., EPS) roaming agreement with the VPLMN provider of the LTERAN 122.

[0030] The network arrangement 100 also includes a cellular core network 130, the Internet 140, an IP Multimedia Subsystem (IMS) 150, and a network services backbone 160. The cellular core network 130 manages the traffic that flows between the cellular network and the Internet 140. The IMS 150 may be generally described as an architecture for delivering multimedia services to the UE 110 using the IP protocol. The IMS 150 may communicate with the cellular core network 130 and the Internet 140 to provide the multimedia services to the UE 110. The network services backbone 160 is in communication either directly or indirectly with the Internet 140 and the cellular core network 130. The network services backbone 160 may be generally described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that may be used to extend the functionalities of the UE 110 in communication with the various networks.

[0031] Fig. 2 shows an example UE 110 according to various example embodiments. The UE 110 will be described with regard to the network arrangement 100 of Fig. 1. The UE 110 may represent any electronic device and may include a processor 205, a memory arrangement 210, a display device 215, an input / output (I / O) device 220, a transceiver 225, and other components 230. The other components 230 may include, for example, an audio input device, an audio output device, a battery that provides a limited power supply, a data acquisition device, ports to electrically connect the UE 110 to other electronic devices, sensors to detect conditions of the UE 110, etc.

[0032] The processor 205 may be configured to execute a plurality of engines for the UE 110 . For example , the engines may include an EPS roaming engine 235 for performing operations related to roaming to an EPS when a 5GS is in a disaster condition . The operations include, but are not limited to , determining parameters related to the EPS roaming, determining the 5GS is in a disaster condition and sending attach request ( s ) and / or tracking area update ( TAU) request messages to the EPS when the 5GS is in a disaster condition . Each of these example operations will be described in more detail below .

[0033] The above referenced engine being an application ( e . g . , a program) executed by the processor 205 is only an example . The functionality associated with the engines may also be represented as a separate incorporated component of the UE 110 or may be a modular component coupled to the UE 110 , e . g . , an integrated circuit with or without firmware . For example , the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information . The engines may also be embodied as one application or separate applications . In addition, in some UEs , the functionality described for the processor 205 is split among two or more processors such as a baseband processor and an applications processor . The example embodiments may be implemented in any of these or other configurations of a UE .

[0034] The memory arrangement 210 may be a hardware component configured to store data related to operations performed by the UE 110 . The display device 215 may be a hardware component configured to show data to a user while the I / O device 220 may be a hardware component that enables the user to enter inputs .The display device 215 and the I / O device 220 may be separate components or integrated together such as a touchscreen.

[0035] The transceiver 225 may be a hardware component configured to establish a connection with the 5G NR-RAN 120, an LTE-RAN (not pictured) , a legacy RAN (not pictured) , a WLAN (not pictured) , etc. Accordingly, the transceiver 225 may operate on a variety of different frequencies or channels (e.g. , set of consecutive frequencies) . The transceiver 225 includes circuitry configured to transmit and / or receive signals (e.g. , control signals, data signals) . Such signals may be encoded with information implementing any one of the methods described herein. The processor 205 may be operably coupled to the transceiver 225 and configured to receive from and / or transmit signals to the transceiver 225. The processor 205 may be configured to encode and / or decode signals (e.g., signaling from a base station of a network) for implementing any one of the methods described herein.

[0036] Fig. 3 shows an example base station 300 according to various example embodiments. The base station 300 may represent the gNB 120A, the eNB 122A or any other access node through which the UE 110 may establish a connection and manage network operations .

[0037] The base station 300 may include a processor 305, a memory arrangement 310, an input / output (I / O) device 315, a transceiver 320, and other components 325. The other components 325 may include, for example, an audio input device, an audio output device, a battery, a data acquisition device, ports toelectrically connect the base station 300 to other electronic devices and / or power sources, etc.

[0038] The processor 305 may be configured to execute a plurality of engines for the UE 110. For example, the engines may include an EPS roaming engine 330 for performing operations related to configuring a UE with operations related to EPS roaming when a 5GS is in a disaster condition. When the base station 300 is a base station of a 5GS, the operations include, but are not limited to, configuring the UE 110 with parameters related to EPS roaming when the 5GS is in a disaster condition and indicating to the UE 110 when the 5GS is available and no longer in the disaster condition. When the base station 300 is a base station of an EPS, the operations include, but are not limited to, configuring the UE 110 with parameters related to EPS roaming when the 5GS is in a disaster condition, receiving attach requests from the EPS, forwarding attach accept messages to the UE, receiving TAU requests, forwarding TAU accept messages to the UE and indicating to the UE 110 when the 5GS is available and no longer in the disaster condition. Each of these example operations will be described in more detail below.

[0039] The memory arrangement 310 may be a hardware component configured to store data related to operations performed by the base station 300. The I / O device 315 may be a hardware component or ports that enable a user to interact with the base station 300. The transceiver 320 may be a hardware component configured to exchange data with the UE 110 and any other UE in the network arrangement 100.

[0040] The transceiver 320 may be a hardware component configured to exchange data with the UE 110 and any other UE in the network arrangement 100. The transceiver 320 may operate on a variety of different frequencies or channels (e.g. , set of consecutive frequencies) . The transceiver 320 includes circuitry configured to transmit and / or receive signals (e.g. , control signals, data signals) . Such signals may be encoded with information implementing any one of the methods described herein. The processor 305 may be operably coupled to the transceiver 320 and configured to receive from and / or transmit signals to the transceiver 320. The processor 305 may be configured to encode and / or decode signals (e.g., signaling from a UE) for implementing any one of the methods described herein.

[0041] As described above, the example embodiments relate to a scenario where a UE that has 5G-only national roaming may register for a Disaster Roaming service in an Evolved Packet System (EPS) of the same Visited Public Land Mobile Network (VPLMN) . Thus, the EPS (e.g. , 4G system) may provide the Disaster Roaming service. To minimize the impact to the Evolved Packet Core (EPC) , the configuration and provisioning of the UE for Disaster Roaming may be performed by its 5G Home PLMN (HPLMN) or a 5G VPLMN while roaming. This ensures that a 4G only UE does not support MINT. From the perspective of the 5G System (5GS) , a UE currently registered with Disaster Roaming on the 5GS, interworking with the EPC is forbidden.

[0042] Prior to describing further operations of the example embodiments, some example scenarios to which the example embodiments may be applied are described. The example scenarios are not the only scenarios to which the example embodimentsapply but are merely described to provide context for the example embodiments. In a first example scenario, a UE may be registered with its 5G HPLMN. The 5G HPLMN may experience a disaster condition such that the UE is de-registered from the 5G HPLMN. The HPLMN may have a roaming agreement with a VPLMN but that roaming agreement may be for 5G only service, meaning that EPS roaming to the VPLMN is forbidden. However, according to the example embodiments, when a disaster condition applies to the 5G HPLMN, the UE may be allowed to register with the EPC of the VPLMN to resume 4G connectivity service.

[0043] In a second example scenario, a UE may roam into a 5G VPLMN which has a roaming agreement with the 5G HPLMN of the UE . In the example scenario, the UE may be an international roamer that has a 5G-only roaming access to the 5G VPLMN. Subject to the roaming agreement, national roaming may be forbidden in EPS (e.g., a UE can register with a 5G VPLMN but it cannot register with the EPC of this VPLMN) . The legacy 4G network which is not virtualized and isolated from 5G may function well when the 5G network fails. Such a legacy 4G deployment is particularly common in the areas where 5G national roaming is allowed (e.g. , rural areas) . When a disaster condition applies to the 5G VPLMN, the UE may be allowed to register with the EPC of the VPLMN to resume 4G connectivity service.

[0044] Fig. 4 shows an example call flow 400 for a UE in a disaster condition according to various example embodiments. The example call flow 400 is performed by a UE 110 that is initially operating on a 5G HPLMN 402. The 5G HPLMN 402 may include a base station (e.g. , gNB 120A) described above. In addition, the 5G HPLMN 402 may also include an Access and Mobility ManagementFunction (AMF) 404. The AMF 404 may be a control plane network function of a 5GC. The AMF 404 may handle registration, authentication and authorization of the UE to the 5G HPLMN 402.

[0045] The call flow 400 also includes a 4G VPLMN 410 that includes a base station (e.g., eNB 412) and a Mobility Management Entity (MME) 414. The MME 414 may handle security, connectivity, mobility, and inter-network communication for the 4G VPLMN 410. In the call flow 400, the 5G HPLMN 402 may be the PLMN with disaster condition and the 4G VPLMN 410 may be the PLMN without disaster condition. The operations associated with each of the elements in the call flow 400 are described in greater detail below.

[0046] In 420, the UE 110 may be pre-configured by the 5G HPLMN 402 with information related to disaster roaming to EPS. This pre-conf iguration information may be stored in the UE 110 in for example, a universal integrated circuit card (UICC) , an embedded UICC (eUICC) , Universal Subscriber Identity Module (USIM) , etc. The pre-configured information may include an indication that disaster roaming to EPS is enabled in the UE 110. The pre-conf iguration may also include a list of PLMN(s) that may be used in a disaster condition. This list may include the 4G VPLMN 410. The list may be in an order of decreasing priority. If the UE 110 were currently roaming, the VPLMN to which the UE is roaming (e.g., Registered PLMN) may provide a similar list of PLMN(s) to be used in a disaster condition in an order of decreasing priority. This list may be provided after a successful registration procedure with the VPLMN.

[0047] The pre-conf iguration may also include a disaster roaming wait range that includes a minimum wait time and a maximum wait time and a disaster return wait range that includes a minimum wait time and a maximum wait time . The disaster roaming wait range may be used to prevent signaling overload in the PLMN providing disaster roaming ( e . g . , the 4G VPLMN 410 ) . For example , the 5G HPLMN 402 ( or the registered PLMN) may provide restrictions on the time when the UE 110 may initiate the attach request for disaster roaming service upon arriving in the PLMN providing disaster roaming service . For example, upon selecting a PLMN for disaster roaming if the UE 110 has a stored disaster roaming wait range, the UE 110 may generate a random number within the disaster roaming wait range and start a timer with the generated random number . While the timer is running, the UE 110 may not initiate an attach request on the selected PLMN . When the timer expires , the UE 110 may perform an attach request i f still camped on the selected PLMN .

[0048] The disaster return wait range may provide the same functionality as the disaster roaming wait range , except it provides the UE 110 with a range of times to wait to re-attach to the PLMN that was under disaster condition, e . g . , the 5G HPLMN 402 . This may prevent the 5G HPLMN from signaling overload as it comes out of the disaster condition .

[0049] The NAS protocol may enable the network to update the provisioned information in the UE 110 for example, during registration or a configuration update procedure in 5GS . The provisioned information can be used by the UE 110 under disaster conditions when roaming in EPS . In some example embodiments , some of this information may be provided in EPS if the UE 110supports MINT. In these example embodiments, when the UE 110 supports MINT and the UE 110 performs an EPS attach or disaster roaming attach, some of the information may be provided to the UE 110. In some example embodiments, a new access identity may be defined to differentiate inbound roamers for disaster roaming services .

[0050] In some example embodiments, extensions to Access Barring, Access Class Barring, Extended Access Barring or Application specific Congestion control for Data Communication (ACDC) when the UE is registering or registered for disaster roaming services so as to disable access class control, e.g., TS 24.301, Section 5.3.10. These extensions may be used to mitigate overload due to disaster inbound roamers to the PLMN providing disaster roaming.

[0051] In 425, the UE 110 sends a registration request to the AMF 404 via the gNB 120A. The registration request may include, for example, a 5GS registration type. In this example, the registration type may be an initial registration request. However, there are other types of registration requests, e.g., disaster roaming initial request, mobility registration updating, periodic registration updating, emergency registration, etc. However, for the purposes of this call flow 400, it is considered that the registration type may be an initial registration request. The registration request may also include other information such as a 5G Mobility Management (5GMM) capability, etc.

[0052] In the example of call flow 400, it may be considered that the registration request is accepted by the network. Thus,in 430, the UE 110 may receive a registration accept from the AMF 404 via the gNB 120A. The registration accept may include information related to disaster conditions. For example, the registration accept may include a disaster roaming wait range, a disaster return wait range and a list of PLMNs to be used in disaster conditions. These parameters were described above with respect to the pre-conf iguration by the HPLMN in 420. As described above, the parameters related to disaster roaming may also be provided or updated for the UE 110 during a registration (or configuration update) . Thus, in this example, parameters related to disaster roaming may be included in the registration accept message.

[0053] In this example call flow 400, the UE 110 has successfully registered with the 5G HPLMN 402. However, in 435, the UE 110 suffers a loss of connectivity with the 5G HPLMN 402 and is de-registered, e.g., because of a disaster condition in the 5G HPLMN 402. In 440, the eNB 412 of the VPLMN 410 may broadcast a system information block (SIB) indicating there is a disaster condition, the 4G VPLMN 410 is available for roaming and the 5G HPLMN 402 is a roaming partner with the 4G PLMN 410. For example, the SIB may include a list of one or more PLMN(s) with disaster condition for which disaster roaming service is offered by the available 4G VPLMN.

[0054] Based on the SIB, the UE 110 may determine the disaster condition (e.g. , the 5G HPLMN 402 is under a disaster condition) and that the 4G VPLMN 410 is a disaster condition roaming partner of the 5G HPLMN 402. Based on this determination, the UE 110 may perform network selection and access control for disaster roaming. For example, in 445, the UE110 may send an EPS attach request to the MME 414 of the 4G VPLMN 410 via the eNB 412.

[0055] Fig. 5 shows an example of an EPS attach request message contents 500 according to various example embodiments. The attach request is sent by the UE 110 to the 4G VPLMN 410 to perform an attach procedure. The EPS attach request message contents 500 may be for the attach request sent to the MME 414 of the 4G VPLMN 410 in 445. A first example field may be an EPS attach type 510. The UE 110 may set the EPS attach type to Disaster roaming attach when attaching to the 4G VPLMN 410.

[0056] Fig. 6 shows an example of an EPS attach type information element (IE) 600 according to various example embodiments. The EPS attach type IE 600 may be the IE provided in the EPS attach type 510 of the attach request message contents 500. The purpose of the EPS attach type IE 600 is to indicate the type of the requested attach. In this example, the EPS attach type IE 600 may be set to a disaster roaming attach as indicated by the field 610 in the EPS attach type IE 600.

[0057] Returning to Fig. 5, a second example field in the EPS attach request message contents 500 may be a UE network capability IE 520. The UE 110 may indicate its capability to support MINT. Fig. 7 shows an example of a UE network capability IE 700 according to various example embodiments. The purpose of the UE network capability IE 700 is to provide the network with information concerning aspects of the UE 110 related to EPS or interworking with general packet radio service (GPRS) and 5GS . The contents may affect the manner in which the network handles the operation of the UE 110. The UE networkcapability IE 700 indicates general UE characteristics and, except for fields explicitly indicated, is independent of the frequency band of the channel on which it is sent. In this example, the UE 110 may indicate support of MINT by setting the minimization of service interruption bit 710 in the UE network capability IE 700 to MINT supported in EPS, e.g., bit 710 set to 0 indicates MINT is not supported in EPS, while bit 710 set to 1 indicates MINT is supported in EPS.

[0058] Returning to Fig. 5, a third example field of the EPS attach request message contents 500 may be an MS determined PLMN with disaster condition IE 530. The UE 110 may include this IE 530 when the UE is indicating the MS determined PLMN with disaster condition, e.g. , as determined as specified in 3GPP Technical Specification (TS) 23.122. If the UE 110 is attaching under disaster conditions in the scenario described with regard to the call flow 400, the UE 110 may include the MS determined PLMN with disaster condition IE 530 set to the 5G HPLMN 402 to indicate the PLMN with disaster condition determined by the UE 110.

[0059] While not shown in the call flow 400, the MME 414 may provide the disaster roaming service indication received from the UE 110 to a Home Subscriber Server (HSS) and / or a Signaling Gateway (S-GW) of the 4G VPLMN 410 to verify the subscription of the UE 110 (or the user of the UE 110) and verify the roaming agreements associated with the subscription. In this example scenario, it is considered that the UE 110 is allowed to disaster roam to the 4G VPLMN 410, e.g., the verifications of the MME 414 are successful.

[0060] Returning to Fig. 4, in 450, the MME 414 of the 4G VPLMN 410 may provide an attach accept message to the UE 110 via the eNB 412. The attach accept message may be sent by the network (e.g. , 4G VPLMN 410) to the UE 110 to indicate that the corresponding attach request has been accepted.

[0061] Fig. 8 shows an example of an EPS attach accept message contents 800 according to various example embodiments. A first example field may be an EPS attach result IE 810. The purpose of the EPS attach result IE 810 is to specify the result of the attach procedure.

[0062] Fig. 9 shows an example of an EPS attach result IE 900 according to various example embodiments. The EPS attach result IE 900 may be a type 1 information element. If the UE 110 has set the EPS attach type to disaster roaming attach in the attach request of 445, but the MME 414 of the 4G VPLMN 410 cannot attach the UE 110 for disaster conditions, the MME 410 may set the EPS attach result 810 in the EPS attach accept message 800 to request for attach for disaster roaming service accepted as registration not for disaster roaming service as shown in the field 910 of Fig. 9. Otherwise, if the UE 110 is registered for disaster conditions by the MME 414, the EPS attach result 810 may be set to one of the other values shown in Fig. 9.

[0063] Returning to Fig. 8, other example fields related to disaster roaming may be a disaster roaming wait range IE 820, a disaster return wait range IE 830 and a list of PLMNs to be used in disaster IE 840. These parameters were described above with respect to the pre-conf iguration by the HPLMN in 420. As described above, in some example embodiments, some of theparameters related to disaster roaming may be provided in EPS if the UE 110 supports MINT. In these example embodiments, when the UE 110 supports MINT and the UE 110 performs an EPS attach or disaster roaming attach, some of the information may be provided to the UE 110 as shown in the example of Fig. 8. There is no requirement that the EPS provide this information, only that in some example embodiments the EPS is allowed to provide this information .

[0064] In 455, the UE 110 may send a tracking area update (TAU) request to the MME 414 of the 4G VPLMN 410 via the eNB 412. Under normal conditions the UE 110 sends a TAU request message to the MME 414 with an EPS update type set to TA updating. Under disaster conditions, the UE 110 may send a TAU request with the EPS update type set to disaster roaming update.

[0065] Fig. 10 shows an example of an EPS Tracking Area Update (TAU) request message contents 1000 according to various example embodiments. A first example field of the EPS TAU request message 1000 may be an EPS update type 1010. The purpose of the EPS update type IE 1010 is to specify the area with which the updating procedure is associated. The EPS update type IE 1010 is a type 1 information element.

[0066] Fig. 11 shows an example of an EPS update type IE 1100 according to various example embodiments. As shown in Fig. 11, when the TAU update request is sent under disaster conditions, the EPS update type may be set to disaster roaming updating as shown in the field 1110.

[0067] Returning to Fig. 10, the EPS TAU request message 1000 may also include a UE network capability field 1020. This field allows the UE 110 to indicate its capability to support MINT. An example of an EPS UE network capability IE 700 was provided above with respect to Fig. 7. To indicate support of MINT, the UE 110 may set the MINT bit 710 to MINT supported in EPS.

[0068] A third example field of the EPS TAU request message 1000 may be an MS determined PLMN with disaster condition IE 1030. The UE 110 may include this IE 1030 when the UE is requesting a TAU under disaster conditions to indicate the MS determined PLMN with disaster condition, e.g., as determined as specified in 3GPP Technical Specification (TS) 23.122. If the UE 110 is requesting a TAU update under disaster conditions in the scenario described with regard to the call flow 400, the UE 110 may include the MS determined PLMN with disaster condition IE 1030 set to the 5G HPLMN 402 to indicate the PLMN with disaster condition determined by the UE 110.

[0069] Returning to Fig. 4, in 460, the MME 414 of the 4G VPLMN 410 may provide a TAU accept message to the UE 110 via the eNB 412. The TAU accept message may be sent by the network (e.g., 4G VPLMN 410) to the UE 110 to indicate that the corresponding update request has been accepted.

[0070] Fig. 12 shows an example of an EPS TAU accept message contents 1200 according to various example embodiments. A first example field may be an EPS update result IE 1210. The purpose of the EPS attach result IE 810 is to specify the result of the associated update procedure.

[0071] Fig. 13 shows an example of an EPS update result IE 1300 according to various example embodiments. The EPS update result IE 1300 may be a type 1 information element. If the UE 110 has set the EPS update type to disaster roaming updating in the TAU request of 455, but the MME 414 of the 4G VPLMN 410 cannot attach the UE 110 for disaster conditions, the MME 410 may set the EPS attach result 1210 in the EPS TAU accept message 1200 to request for attach for disaster roaming service accepted as registration not for disaster roaming service as shown in the field 1310 of Fig. 13. Otherwise, if the UE 110 is registered for disaster conditions by the MME 414, the EPS TAU result 1210 may be set to one of the other values shown in Fig. 13.

[0072] Returning to Fig. 12, other example fields related to disaster roaming may be a disaster roaming wait range IE 1220, a disaster return wait range IE 1230 and a list of PLMNs to be used in disaster IE 1240. These parameters were described above with respect to the pre-conf iguration by the HPLMN in 420. As described above, in some example embodiments, some of the parameters related to disaster roaming may be provided in EPS if the UE 110 supports MINT. In these example embodiments, when the UE 110 supports MINT and the UE 110 performs a TAU update or TAU disaster roaming update, some of the information may be provided to the UE 110 as shown in the example of Fig. 12. There is no requirement that the EPS provide this information, only that in some example embodiments the EPS is allowed to provide this information .

[0073] Returning to Fig. 4, in 465, the 5G HPLMN 402 that was affected by the disaster condition, may broadcast (e.g., via a SIB) an indication of the end of the disaster condition and theavailability of normal service in the impacted area. In the example of call flow 400, the gNB 120A may be the component that broadcasts the SIB. However, all gNBs in the impacted area may transmit the SIB.

[0074] In other example embodiments, the E-UTRAN in the VPLMN that provides the disaster roaming service (e.g., the 4G VPLMN 410) may also provide such an indication to the UE 110. This indication may be a message sent directly to the UE 110 or may also be a broadcast (e.g., SIB) .

[0075] In 470, the UE 110 may de-register from the 4G VPLMN 410 based on the disaster condition with the 5G HPLMN 402 being finished. In 475 and 480, the UE 110 may re-register with the 5G HPLMN 402. The operations 475 and 480 are similar to the operations 425 and 430, respectively, described above. Thus, when the disaster condition is over, the UE 110 may again register with the 5G HPLMN 402.Examples

[0076] In a first example, a method, comprising processing, based on signaling from a network, parameters related to roaming to an Evolved Packet System (EPS) when a Fifth Generation System (5GS) is in a disaster condition, wherein a subscriber to a Public Land Mobile Network (PLMN) provider operating the 5GS has a 5G only roaming agreement with a PLMN operating the EPS, determining the 5GS is in the disaster condition and generating, for transmission to the EPS, an attach reguest to attach to theEPS during the disaster condition.

[0077] In a second example, the method of the first example, wherein the parameters related to roaming to the EPS when the 5GS is in the disaster condition comprise one of an indication of whether disaster roaming is enabled, a list of PLMNs to be used in the disaster condition comprising the EPS, a disaster roaming wait range comprising a minimum wait time and a maximum wait time or a disaster return wait range comprising a minimum wait time or a maximum wait time.

[0078] In a third example, the method of the second example, wherein the signaling from the network comprises a preconfiguration from the 5GS .

[0079] In a fourth example, the method of the first example, further comprising generating, for transmission to the 5GS, a registration request, wherein the signaling from the network comprises a registration accept message in response to the registration request.

[0080] In a fifth example, the method of the first example, wherein determining the 5GS is in the disaster condition is based on processing, based on a system information block (SIB) broadcast by the EPS, an indication that the 5GS is in a disaster condition.

[0081] In a sixth example, the method of the fifth example, wherein the SIB further comprises an indication that the EPS is providing disaster roaming for the 5GS .

[0082] In a seventh example, the method of the first example, wherein the signaling from the network comprises an attach accept message in response to the attach request.

[0083] In an eighth example, the method of the seventh example, wherein the attach request comprises an indication that the attach request is for a disaster roaming attach type.

[0084] In a ninth example, the method of the seventh example, wherein the attach request comprises an indication that a minimization of service interruption (MINT) is supported.

[0085] In a tenth example, the method of the seventh example, wherein the attach request comprises an indication of a mobile subscriber (MS) determined PLMN with the disaster condition identifying the 5GS as the PLMN with the disaster condition.

[0086] In an eleventh example, the method of the seventh example, wherein the attach accept message comprises an indication that the attach request is accepted as registration not for disaster roaming service when the EPS does not accept the attach request for disaster roaming.

[0087] In a twelfth example, the method of the seventh example, further comprising generating, for transmission to the EPS, a tracking area update (TAU) request, wherein the signaling from the network comprises a TAU accept message in response to the TAU request.

[0088] In a thirteenth example, the method of the twelfth example, wherein the TAU request comprises an indication that the TAU request is for a disaster roaming updating type.

[0089] In a fourteenth example, the method of the twelfth example, wherein the TAU request comprises an indication that a minimization of service interruption (MINT) is supported.

[0090] In a fifteenth example, the method of the twelfth example, wherein the TAU request comprises an indication of a mobile subscriber (MS) determined PLMN with the disaster condition identifying the 5GS as the PLMN with the disaster condition .

[0091] In a sixteenth example, the method of the twelfth example, wherein the TAU accept message comprises an indication that the TAU request is accepted as registration not for disaster roaming service when the EPS does not accept the TAU request for disaster roaming.

[0092] In a seventeenth example, the method of the first example, further comprising determining the 5GS is available and not in the disaster condition, detaching from the EPS and generating, for transmission to the 5GS, a registration request, wherein the signaling from the network comprises a registration accept message in response to the registration request.

[0093] In an eighteenth example, the method of the seventeenth example, wherein the determining the 5GS is available and not in the disaster condition is based on processing, based on a system information block (SIB) broadcast by the 5GS, an indication that the 5GS is available and not in the disaster condition.

[0094] In a nineteenth example, the method of the seventeenth example, wherein the determining the 5GS is available and not in the disaster condition is based on processing, based on signaling from the EPS, an indication that the 5GS is available and not in the disaster condition.

[0095] In a twentieth example, the method of the first example, wherein the PLMN provider operating the 5GS is a home PLMN (HPLMN) of the subscriber.

[0096] In a twenty first example, the method of the first example, wherein the PLMN provider operating the 5GS is a visited PLMN (VPLMN) .

[0097] In a twenty second example, a processor configured to perform any of the methods of the first through twenty first examples .

[0098] In a twenty third example, a user equipment (UE) configured to perform any of the methods of the first through twenty first examples.

[0099] In a twenty fourth example, a method, comprising determining a Fifth Generation System (5GS) is in a disaster condition, determining the EPS provides support for roaming for a subscriber of the 5GS in the disaster condition, wherein the EPS does not support roaming for the subscriber in non-disaster conditions and generating, for broadcast by the EPS, an indication of the disaster condition and support of roaming for the 5GS in the disaster condition.

[0100] In a twenty fifth example, the method of the twenty fourth example, further comprising processing, based on signaling from a user equipment (UE) , an attach request for the UE to attach to the EPS, wherein the attach request comprises an indication that the attach request is for a disaster roaming attach type.

[0101] In a twenty sixth example, the method of the twenty fifth example, wherein the attach request further comprises an indication that the UE supports a minimization of service interruption (MINT) .

[0102] In a twenty seventh example, the method of the twenty fifth example, wherein the attach request further comprises an indication of a mobile subscriber (MS) determined PLMN with the disaster condition identifying the 5GS as a Public Land Mobile Network (PLMN) with the disaster condition.

[0103] In a twenty eighth example, the method of the twenty sixth example, further comprising determining, based on the attach request, whether the UE is allowed to roam to the EPS when the 5GS is in the disaster condition.

[0104] In a twenty ninth example, the method of the twenty sixth example, further comprising generating, for transmission to the UE, an attach accept message.

[0105] In a thirtieth example, the method of the twenty ninth example, wherein the attach accept message indicates the UE has successfully attached to the EPS.

[0106] In a thirty first example , the method of the twenty ninth example , wherein the attach accept message comprises an indication that the attach request is accepted as registration not for disaster roaming service when the EPS does not accept the attach request for disaster roaming .

[0107] In a thirty second example , the method of the twenty ninth example , wherein the attach accept message comprises parameters related to roaming to the EPS when the 5GS is in the disaster condition .

[0108] In a thirty third example , the method of the thirty second example , wherein the parameters related to roaming to the EPS when the 5GS is in the disaster condition comprise one of an indication of whether disaster roaming is enabled, a list of PLMNs to be used in the disaster condition comprising the EPS , a disaster roaming wait range comprising a minimum wait time and a maximum wait time or a disaster return wait range comprising a minimum wait time or a maximum wait time .

[0109] In a thirty fourth example , the method of the twenty fi fth example , further comprising processing, based on signaling from the UE , a tracking area update ( TAU) request, wherein the TAU request comprises an indication that the TAU request is for a disaster roaming updating type .

[0110] In a thirty fi fth example , the method of the thirty fourth example , wherein the TAU request comprises an indication that the UE supports a minimi zation of service interruption (MINT ) .

[0111] In a thirty sixth example, the method of the thirty fourth example, wherein the TAU request further comprises an indication of a mobile subscriber (MS) determined PLMN with the disaster condition identifying the 5GS as a Public Land Mobile Network (PLMN) with the disaster condition.

[0112] In a thirty seventh example, the method of the thirty sixth example, further comprising determining, based on the TAU request, whether the UE is allowed to roam to the EPS when the 5GS is in the disaster condition.

[0113] In a thirty eighth example, the method of the thirty seventh example, further comprising generating, for transmission to the UE, a TAU accept message.

[0114] In a thirty ninth example, the method of the thirty eighth example, wherein the TAU accept message indicates the TAU was successful.

[0115] In a fortieth example, the method of the thirty eighth example, wherein the TAU accept message comprises an indication that the TAU request is accepted as an update not for disaster roaming service when the EPS does not accept the attach request for disaster roaming.

[0116] In a forty first example, the method of the thirty eighth example, wherein the TAU accept message comprises parameters related to roaming to the EPS when the 5GS is in the disaster condition.

[0117] In a forty second example, the method of the forty first example, wherein the parameters related to roaming to the EPS when the 5GS is in the disaster condition comprise one of an indication of whether disaster roaming is enabled, a list of PLMNs to be used in the disaster condition comprising the EPS, a disaster roaming wait range comprising a minimum wait time and a maximum wait time or a disaster return wait range comprising a minimum wait time or a maximum wait time.

[0118] In a forty third example, a Mobility Management Entity (MME) of an Evolved Packet System (EPS) configured to perform any of the methods of the twenty fourth through forty second examples .

[0119] In a forty fourth example, one or more processors configured to perform any of the methods of the twenty fourth through forty second examples.

[0120] Those skilled in the art will understand that the above-described example embodiments may be implemented in any suitable software or hardware configuration or combination thereof. An example hardware platform for implementing the example embodiments may include, for example, an Intel x86 based platform with compatible operating system, a Windows OS, a Mac platform and MAC OS, a mobile device having an operating system such as iOS, Android, etc. The example embodiments of the above described method may be embodied as a program containing lines of code stored on a non-transitory computer readable storage medium that, when compiled, may be executed on a processor or microprocessor .

[0121] Although this application described various embodiments each having different features in various combinations , those skilled in the art will understand that any of the features of one embodiment may be combined with the features of the other embodiments in any manner not speci fically disclaimed or which is not functionally or logically inconsistent with the operation of the device or the stated functions of the disclosed embodiments .

[0122] It is well understood that the use of personally identi fiable information should follow privacy policies and practices that are generally recogni zed as meeting or exceeding industry or governmental requirements for maintaining the privacy of users . In particular, personally identifiable information data should be managed and handled so as to minimi ze risks of unintentional or unauthori zed access or use , and the nature of authori zed use should be clearly indicated to users .

[0123] It will be apparent to those skilled in the art that various modi fications may be made in the present disclosure , without departing from the spirit or the scope of the disclosure . Thus , it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalent .

Claims

What is claimed:

1. An apparatus comprising processing circuitry configured to: process, based on signaling from a network, parameters related to roaming to an Evolved Packet System (EPS) when a Fifth Generation System (5GS) is in a disaster condition, wherein a subscriber to a Public Land Mobile Network (PLMN) provider operating the 5GS has a 5G only roaming agreement with a PLMN operating the EPS; determine the 5GS is in the disaster condition; and generate, for transmission to the EPS, an attach request to attach to the EPS during the disaster condition.

2. The apparatus of claim 1, wherein the parameters related to roaming to the EPS when the 5GS is in the disaster condition comprise one of an indication of whether disaster roaming is enabled, a list of PLMNs to be used in the disaster condition comprising the EPS, a disaster roaming wait range comprising a minimum wait time and a maximum wait time or a disaster return wait range comprising a minimum wait time or a maximum wait time .

3. The apparatus of claim 1, wherein the processing circuitry is further configured to: generate, for transmission to the 5GS, a registration request, wherein the signaling from the network comprises a registration accept message in response to the registration request .

4. The apparatus of claim 1, wherein determining the 5GS is in the disaster condition is based on the processing circuitry being configured to:process, based on a system information block (SIB) broadcast by the EPS, an indication that the 5GS is in a disaster condition.

5. The apparatus of claim 4, wherein the SIB further comprises an indication that the EPS is providing disaster roaming for the 5GS .

6. The apparatus of claim 1, wherein the signaling from the network comprises an attach accept message in response to the attach request.

8. The apparatus of claim 6, wherein the processing circuitry is further configured to: generate, for transmission to the EPS, a tracking area update (TAU) request, wherein the signaling from the network comprises a TAU accept message in response to the TAU request.

9. The apparatus of claim 1, wherein the processing circuitry is further configured to: determine the 5GS is available and not in the disaster condition; detach from the EPS; and generate, for transmission to the 5GS, a registration request, wherein the signaling from the network comprises a registration accept message in response to the registration request .

10. The apparatus of claim 9, wherein the determining the 5GS is available and not in the disaster condition is based on the processing circuitry being configured to:process, based on a system information block (SIB) broadcast by the 5GS, an indication that the 5GS is available and not in the disaster condition.

11. The apparatus of claim 9, wherein the determining the 5GS is available and not in the disaster condition is based on the processing circuitry being configured to: process, based on signaling from the EPS, an indication that the 5GS is available and not in the disaster condition.

12. A Mobility Management Entity (MME) of an Evolved Packet System (EPS) configured to: determine a Fifth Generation System (5GS) is in a disaster condition; determine the EPS provides support for roaming for a subscriber of the 5GS in the disaster condition, wherein the EPS does not support roaming for the subscriber in non-disaster conditions; and generate, for broadcast by the EPS, an indication of the disaster condition and support of roaming for the 5GS in the disaster condition.

13. The MME of claim 12, further configured to: process, based on signaling from a user equipment (UE) , an attach request for the UE to attach to the EPS, wherein the attach request comprises an indication that the attach request is for a disaster roaming attach type.

14. The MME of claim 13, wherein the attach request further comprises an indication that the UE supports a minimization of service interruption (MINT) .

15. The MME of claim 14, further configured to: determine, based on the attach request, whether the UE is allowed to roam to the EPS when the 5GS is in the disaster condition .

16. The MME of claim 14, further configured to: generate, for transmission to the UE, an attach accept message .

17. The MME of claim 16, wherein the attach accept message comprises an indication that the attach request is accepted as registration not for disaster roaming service when the EPS does not accept the attach request for disaster roaming.

18. The MME of claim 16, wherein the attach accept message comprises parameters related to roaming to the EPS when the 5GS is in the disaster condition.

19. The MME of claim 18, wherein the parameters related to roaming to the EPS when the 5GS is in the disaster condition comprise one of an indication of whether disaster roaming is enabled, a list of PLMNs to be used in the disaster condition comprising the EPS, a disaster roaming wait range comprising a minimum wait time and a maximum wait time or a disaster return wait range comprising a minimum wait time or a maximum wait time .

20. The MME of claim 13, wherein the processing circuitry is further configured to:process, based on signaling from the UE, a tracking area update (TAU) request, wherein the TAU request comprises an indication that the TAU request is for a disaster roaming updating type.

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