Patent Application
20220225074
The present disclosure relates to mobile communication network arrangements and methods for operating a mobile communication network arrangement to support inter-core network roaming.
Many network operators have begun planning to deploy Fifth Generation (5G) mobile networks. As with their Fourth Generation (4G) Long Term Evolution (LTE) technology, the 3rd Generation Partnership Project (3GPP) has proposed their own 5G technology. The 3GPP is currently defining both a 5G core network—5GC—and a 5G radio access technology—5G New Radio (NR).
The 3GPP has proposed various options for mobile network operators to deploy their 3GPP 5G technologies, many of which integrate both 4G and 5G components to provide radio access to users. It is expected that mobile network operators will select between the various available 3GPP options as they gradually deploy more 5G technologies across their respective networks.
While different 4G and 5G integration options may help expedite 5G deployment, the interworking between 4G and 5G networks may complicate certain operations. One such operation is roaming. Traditionally, a user equipment (UE) uses roaming to operate on a mobile network that is not its home network. Because the UE is not on its home network (Home Public Land Mobile Network (HPLMN)), the visited mobile network (Visited Public Land Mobile Network (VPLMN), also called the serving network) needs to interface with the home mobile network to verify the UE's subscriber information and, if applicable, set up a data connection via the HPLMN.
This roaming procedure has been fully developed for legacy networks as well as some configurations for 5G. The 3GPP, however, has not provided solutions for all 5G deployment options. Thus, mobile network operators may desire new solutions that can support roaming even for complex 5G deployment configurations.
According to one embodiment, a server device includes one or more processors. The one or more processors are configured to identify a home mobile network of a user equipment that attempts to roam in a visited mobile network including the server device, send, to a network function repository function, a service request that identifies the home mobile network, receive, from the network function repository function, a service request response that identifies a home subscriber service in the home mobile network and that identifies the home mobile network as a legacy network of the visited mobile network, retrieve, from the home subscriber service, subscriber information for the user equipment, and configure a roaming connection for the user equipment in the visiting mobile network.
In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various aspects are described with reference to the following drawings, in which:
The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and aspects of this disclosure in which the invention may be practiced. Other aspects may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various aspects of this disclosure are not necessarily mutually exclusive, as some aspects of this disclosure can be combined with one or more other aspects of this disclosure to form new aspects.
Various examples corresponding to aspects of this disclosure are described below:
Example 1 is a server device including one or more processors configured to: identify a home mobile network of a user equipment that attempts to roam in a visited mobile network comprising the server device, send, to a network function repository function, a service request that identifies the home mobile network, receive, from the network function repository function, a service request response that identifies a home subscriber service in the home mobile network and that identifies the home mobile network as a legacy network of the visited mobile network, retrieve, from the home subscriber service, subscriber information for the user equipment, and configure a roaming connection for the user equipment in the visiting mobile network.
In Example 2, the subject matter of Example 1 can optionally include that the one or more processors are configured to retrieve the subscriber information by: sending, on a legacy interface, a subscriber information request to the home subscriber service, and receiving, on the legacy interface, the subscriber information.
In Example 3, the subject matter of Example 2 can optionally include that the legacy interface is an S6a interface that uses a Diameter protocol.
In Example 4, the subject matter of any one of Examples 1 to 3 can optionally include that the one or more processors are configured to configure the roaming connection for the user equipment by establishing a home routing roaming connection for the user equipment with a packet gateway of the home mobile network, a radio access network of the visited mobile network, and a user-plane function of the visited mobile network.
In Example 5, the subject matter of any one of Examples 1 to 3 can optionally include that the one or more processors are configured to configure the roaming connection for the user equipment by establishing a local breakout roaming connection for the user equipment with a radio access network of the visited mobile network and a user-plane function of the visited mobile network.
In Example 6, the subject matter of any one of Examples 4 or 5 can optionally include that the one or more processors are configured to send control signaling to establish the home routing or local breakout roaming connection.
In Example 7, the subject matter of any one of Examples 1 to 6 can optionally include that the one or more processors are further configured to determine, based on the subscriber information, whether the home mobile network permits the user equipment to roam on the visited mobile network.
In Example 8, the subject matter of any one of Examples 1 to 6 can optionally include that the one or more processors are further configured to determine, based on a preconfigured operator policy, whether the visited mobile network permits the user equipment to roam on the visited mobile network.
In Example 9, the subject matter of any one of Examples 1 to 8 can optionally include that the home mobile network is a Fourth Generation, 4G, Evolved Packet Core, EPC, and that the visited mobile network is a Fifth Generation Core, 5GC.
Example 10 is a server device including one or more processors configured to: identify a home mobile network of a user equipment that attempts to roam in a visited mobile network comprising the server device, determine, based on preconfigured information in the server device, that the home mobile network is a legacy network of the visited mobile network, retrieve, from a home subscriber service in the home mobile network, subscriber information for the user equipment, and configure a roaming connection for the user equipment in the visiting mobile network.
In Example 11, the subject matter of Example 10 can optionally include that the one or more processors are configured to retrieve the subscriber information from the home subscriber service by: sending, on a legacy interface, a subscriber information request to the home subscriber service, and receiving, on the legacy interface, the subscriber information.
In Example 12, the subject matter of any one of Examples 10 or 11 can optionally include that the one or more processors are configured to configure the roaming connection for the user equipment by establishing a home routing roaming connection for the user equipment with a packet gateway of the home mobile network, a radio access network of the visited mobile network, and a user-plane function of the visited mobile network.
In Example 13, the subject matter of any one of Examples 10 or 11 can optionally include that the one or more processors are configured to configure the roaming connection for the user equipment by establishing a local breakout roaming connection for the user equipment with a radio access network of the visited mobile network, and a user-plane function of the visited mobile network.
In Example 14, the subject matter of any one of Examples 12 or 13 can optionally include that the one or more processors are configured to send control signaling to establish the home routing or local breakout roaming connection.
In Example 15, the subject matter of any one of Examples 10 to 14 can optionally include that the home mobile network is a Fourth Generation, 4G, Evolved Packet Core, EPC, and that the visited mobile network is a Fifth Generation Core, 5GC.
In Example 16, the subject matter of any one of Examples 10 to 15 can optionally include that the one or more processors are further configured to: send, to a network function repository function, a service discovery request that identifies the home mobile network and that indicates the home mobile network is a legacy network, receive, from the network function repository function, a service discovery response that identifies the home subscriber service.
Example 17 is a server device including one or more processors configured to: identify a home mobile network of a user equipment that attempts to roam in a visited mobile network comprising the server device, identify a home subscriber service in the home mobile network and determine that the home mobile network is a legacy network of the visited mobile network, determine that the server device does not support a legacy interface with the home subscriber service, and redirect the user equipment to a second server device in the visited mobile network or to a legacy core network of the visited mobile network.
In Example 18, the subject matter of Example 17 can optionally include that the server device is an access and mobility management function of the visited mobile network and that the second server device is a second access and mobility management function of the visited mobile network that supports a legacy interface with the home subscriber service.
In Example 19, the subject matter of any one of Examples 17 or 18 can optionally include that the one or more processors are configured to identify the home subscriber service in the home mobile network by referencing preconfigured information in the server device that identifies the home subscriber service as a component of the home mobile network.
In Example 20, the subject matter of any one of Examples 17 or 18 can optionally include that the one or more processors are configured to identify the home subscriber service in the home mobile network by sending, to a network function repository function, a service request that identifies the home mobile network, and receiving, from the network function repository function, a service request response that identifies a home subscriber service in the home mobile network and that identifies the home mobile network as a legacy network of the visited mobile network.
In Example 21, the subject matter of any one of Examples 17 to 20 can optionally include that the one or more processors are configured to redirect the user equipment to the second server device in the visited mobile network by sending, to a network function repository function or to a network slice selection function, a service request that requests information of an access and mobility management function that supports a legacy interface with the home subscriber service, receiving a service request response that identifies the second server device, and redirecting the user equipment to the second server device.
Example 22 is a method of handling roaming requests at a server device. The method may include: identifying a home mobile network of a user equipment that attempts to roam in a visited mobile network comprising the server device, sending, to a network function repository function, a service request that identifies the home mobile network, receiving, from the network function repository function, a service request response that identifies a home subscriber service in the home mobile network and that identifies the home mobile network as a legacy network of the visited mobile network, retrieving, from the home subscriber service, subscriber information for the user equipment, and configuring a roaming connection for the user equipment in the visiting mobile network.
In Example 23, the subject matter of Example 22 can optionally include that retrieving the subscriber information includes sending, on a legacy interface, a subscriber information request to the home subscriber service, and receiving, on the legacy interface, the subscriber information.
In Example 24, the subject matter of Example 23 can optionally include that the legacy interface is an S6a interface that uses a Diameter protocol.
In Example 25, the subject matter of any one of Examples 22 to 24 can optionally include that configuring the roaming connection for the user equipment includes: establishing a home routing roaming connection for the user equipment with a packet gateway of the home mobile network, a radio access network of the visited mobile network, and a user-plane function of the visited mobile network.
In Example 26, the subject matter of any one of Examples 22 to 24 can optionally include that configuring the roaming connection for the user equipment includes establishing a local breakout roaming connection for the user equipment with a radio access network of the visited mobile network and a user-plane function of the visited mobile network.
In Example 27, the subject matter of any one of Examples 25 or 26 can optionally include that configuring the roaming connection for the user equipment includes sending control signaling to establish the home routing or local breakout roaming connection.
In Example 28, the subject matter of any one of Examples 22 to 27 can optionally include that the method further includes determining, based on the subscriber information, whether the home mobile network permits the user equipment to roam on the visited mobile network.
In Example 29, the subject matter of any one of Examples 22 to 27 can optionally include that the method further includes determining, based on a preconfigured operator policy, whether the visited mobile network permits the user equipment to roam on the visited mobile network.
In Example 30, the subject matter of any one of Examples 22 to 29 can optionally include that the home mobile network is a Fourth Generation, 4G, Evolved Packet Core, EPC, and that the visited mobile network is a Fifth Generation Core, 5GC.
Example 31 is a method of handling roaming requests at a server device. The method may include: identifying a home mobile network of a user equipment that attempts to roam in a visited mobile network comprising the server device, determining, based on preconfigured information in the server device, that the home mobile network is a legacy network of the visited mobile network, retrieving, from a home subscriber service in the home mobile network, subscriber information for the user equipment, and configuring a roaming connection for the user equipment in the visiting mobile network.
In Example 32, the subject matter of Example 31 can optionally include that retrieving the subscriber information from the home subscriber service includes: sending, on a legacy interface, a subscriber information request to the home subscriber service, and receiving, on the legacy interface, the subscriber information.
In Example 33, the subject matter of any one of Examples 31 or 32 can optionally include that configuring the roaming connection for the user equipment includes establishing a home routing roaming connection for the user equipment with a packet gateway of the home mobile network, a radio access network of the visited mobile network, and a user-plane function of the visited mobile network.
In Example 34, the subject matter of any one of Examples 31 or 32 can optionally include that configuring the roaming connection for the user equipment includes establishing a local breakout roaming connection for the user equipment with a radio access network of the visited mobile network and a user-plane function of the visited mobile network.
In Example 35, the subject matter of any one of Examples 33 or 34 can optionally include that configuring the roaming connection for the user equipment includes sending control signaling to establish the home routing or local breakout roaming connection.
In Example 36, the subject matter of any one of Examples 31 to 35 can optionally include that the home mobile network is a Fourth Generation, 4G, Evolved Packet Core, EPC, and that the visited mobile network is a Fifth Generation Core, 5GC.
In Example 37, the subject matter of any one of Examples 31 to 35 can optionally include that the method further includes sending, to a network function repository function, a service request that identifies the home mobile network and that indicates the home mobile network is a legacy network, and receiving, from the network function repository function, a service response that identifies the home subscriber service.
Example 38 is a method of handling roaming requests at a server device. The method may include: identifying a home mobile network of a user equipment that attempts to roam in a visited mobile network comprising the server device, identifying a home subscriber service in the home mobile network and determine that the home mobile network is a legacy network of the visited mobile network, determine that the server device does not support a legacy interface with the home subscriber service, and redirecting the user equipment to a second server device in the visited mobile network or to a legacy core network of the visited mobile network.
In Example 39, the subject matter of Example 38 can optionally include that the server device is an access and mobility management function of the visited mobile network and wherein the second server device is a second access and mobility management function of the visited mobile network that supports a legacy interface with the home subscriber service.
In Example 40, the subject matter of any one of Examples 38 or 39 can optionally include that identifying the home subscriber service in the home mobile network includes referencing preconfigured information in the server device that identifies the home subscriber service as a component of the home mobile network.
In Example 41, the subject matter of any one of Examples 38 or 39 can optionally include that identifying the home subscriber service in the home mobile network includes sending, to a network function repository function, a service request that identifies the home mobile network, and receiving, from the network function repository function, a service request response that identifies a home subscriber service in the home mobile network and that identifies the home mobile network as a legacy network of the visited mobile network.
In Example 42, the subject matter of any one of Examples 38 to 41 can optionally include that redirecting the user equipment to the second server device in the visited mobile network includes sending, to a network function repository function or to a network slice selection function, a service request that requests information of an access and mobility management function that supports a legacy interface with the home subscriber service, receiving a service request response that identifies the second server device, and redirecting the user equipment to the second server device.
Example 43 is a computer readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to perform the method of any one of Examples 22 to 42.
It should be noted that one or more of the features of any of the examples above may be combined with any one of the other examples.
In the following, various examples will be described in more detail.
The 3GPP has proposed several options for mobile network operators to deploy 5G technologies. Because many such operators have existing 3GPP 4G networks, they have already deployed 4G core networks (Evolved Packet Core (EPC)) and 4G radio access network (e.g., LTE) components. Thus, several of the 3GPP's options deploy a 5G NR radio access network by integrating it with 4G technology. Since these options integrate 5G NR and 4G, they are known as ‘non-standalone’ options.
Mobile network operators may therefore have several options for deploying NR radio access networks alongside their existing LTE infrastructure as they transition from 4G to 5G. In addition to these non-standalone deployment options, the 3GPP has also proposed a standalone 5G deployment option.
Though these different deployment options provide flexibility to mobile network operators, they may also lead to complications. For example, some deployment options may lead to problems for procedures like roaming. In traditional roaming, a UE with a certain home mobile network (termed home public land mobile network (HPLMN)) may connect to a visited mobile network (termed visited public land mobile network (VPLMN)). The visited mobile network may then query the HPLMN network for the UE's subscriber information and, after authenticating the UE, provide the UE with a network connection. With roaming, UEs may still have connectivity even when their home mobile networks are not available.
In 3GPP 4G roaming, the EPC of the visited mobile network may query the EPC of the home mobile network to retrieve the UE's subscriber information. This query uses the legacy 4G EPC interfaces, many of which use Diameter messaging protocol. For example, the mobility management entity (MME) in the visited mobile network may request the UE's subscriber information from the home subscriber service (HSS) in the home mobile network using the S6a interface. That S6a interface is one of several Diameter interfaces that the 3GPP has defined for EPC nodes to communicate with each other.
The 3GPP has also provided support for roaming between 5GC home and visited mobile networks. That support, however, is limited. For example, the 3GPP Release 15 and Release 16 standards only support roaming for 5GC inbound roaming users, meaning that a 5G UE with a 5GC home mobile network can roam on a 5GC visited mobile network.
While the 3GPP has provided a mechanism for UEs with 5GC home mobile networks to roam on 5GC visited mobile networks, the 3GPP standard has not specified an architecture for UEs with home EPC core networks to roam on visited 5GC core networks. For example, referring back to the 5G deployment options in
This disclosure therefore provides mechanisms for inter-core network roaming. These mechanisms include an inter-core interfere architecture as well as procedures for the visited core network to identify a visiting UE's home mobile network, retrieve its subscriber information, and configure an appropriate roaming connection for the visiting UE. With this mechanism, UEs with home EPC core networks (e.g., EPC-only) may be able to roam on visited 5GC core networks. Users may therefore be able to enjoy 5G's superior bandwidth and flexibility even when roaming outside of their own home mobile networks.
Access and management function (AMF) 408 may provide mobility management and access control for the 5GC core network. This may include registering an authenticating attached UEs, handling non-access stratum (NAS) signalling, and performing mobility management mobility management.
Session management function (SMF) 410 may handle session management for UEs connected to the 5GC core network. This may include managing protocol data unit (PDU) sessions and overseeing sessions with user plane function (UPF) 412.
UPF 412 may manage user-plane traffic flow between UEs and data networks (DNs). This may include packet routing and forwarding and Quality of Service (QoS) control.
Visiting UE 416 may have a home mobile network that uses an EPC core network (home EPC core network). As shown in
Because the home mobile network only deploys an EPC core network (e.g., as in deployment option 100 from
AMF 408 may initially start with a target NF that it wants to discover and communicate with. In this example, AMF 408 may not initially know whether the target NF is an EPC NF (e.g., any node in the EPC of another mobile network). As shown in
After identifying the HPLMN ID, AMF 408 may generate and send an NF service discovery request to NRF 406 in stage 504. With that NF service discovery request, AMF 408 may request information on the NF service, e.g., request information on the target NF. AMF 408 may include in the NF service discovery request the HPLMN ID and details on the target NF.
NRF 406 may receive and process the NF Service discovery request, thus identifying the HPLMN ID and NF details. NRF 406 may then, in stage 506, identify the address of the target NF and determine whether the target NF is an EPC component (an EPC indication). In some aspects, the address of the target NF may be a fully qualified domain name (FQDN). In some aspects, the operations and maintenance (O&M) system may have previously configured the FQDN and the EPC indication, and NRF 406 may perform stage 506 by referencing this preconfigured information. The EPC indication can be an explicit indication or implicit. For example, NRF 406 may provide the EPC indication in the form of an NF address (e.g., one or more bit(s) reserved in the NF address which identifies it is an EPC function or dedicated address(es) are reserved for the EPC function(s), which can identify the EPC function).
NRF 406 may then generate and send an NF Service discovery response in stage 508. NRF 406 may include the NF address (e.g., FQDN) and the EPC indication in the NF Service discovery response.
AMF 408 may receive and process the NF Service discovery response to identify the NF address with an EPC indication. Based on the EPC indication, AMF 408 may determine that the target NF is an EPC NF.
Alternatively, the AMF 408 may first identify the HPMLN ID (ID for the home mobile network) of the target NF in stage 502. Based on configuration in the AMF (e.g. local policy configured in the AMF), the AMF 408 determine that UE's home mobile network is an EPC network. For example, operations and maintenance (O&M) system may have previously configured the PLMN ID and the EPC indication in tAMF 408, e.g., preconfigured information specifying that HPLMN ID #1 is an EPC network and HPLMN ID #2 is an 5GC network, etc. Based on options, it is also possible that even if AMF 408 determines the home mobile network is an EPC network, AMF 408 will still
AMF 408 may have several different options once it identifies the target NF is an EPC NF. For example, if the AMF 408 supports an EPC interface with the target NF in its EPC core network, AMF 408 may use the EPC interface to communicate with the target NF. In one example, AMF 408 may use the EPC interface to retrieve subscriber information from a target HSS in a visiting UE's home mobile network.
In other examples, such as where AMF 408 does not support an EPC interface with the target NF, AMF 408 may redirect the visiting UE to use the visited mobile network's EPC. For instance, the visited mobile network may include both a 5GC and an EPC, an the visiting UE may be able to use the visited mobile network's EPC.
Since the home mobile network is a legacy network, the visited mobile network may use various aspects of this disclosure to provide inter-core network roaming to visiting UE 416. Starting with
After receiving the HPLMN ID, AMF 408 may attempt to retrieve the subscriber information for visiting UE 408. Like described for the general EPC NF communication procedure in
NRF 406 may receive the NF Service discovery request and identify the address (e.g., FQDN) of the target NF. NRF 406 may also determine, based on the HPLMN ID and the NF details, that the target NF is an EPC NF. For example, NRF 406 may determine that the target NF is HSS 402 in the EPC of the home mobile network. This information may be preconfigured in NRF 406 by O&M.
NRF 406 may then generate and send an NF service discovery response to AMF 408 in stage 608. The NF service discovery response may include the target NF's address and an EPC indication specifying that the target NF is an HSS.
Based on the NF service discovery response, AMF 408 may determine that the target NF is an EPC NF, and that it is an HSS, i.e., HSS 402. In this example, AMF 408 may be configured to use a legacy interface to communicate with HSS 402. For example, AMF 408 may be configured to communicate with HSS(s) with an S6a interface (e.g., Diameter). AMF 408 may thus determine to use the S6a interface in stage 610 of this example.
AMF 608 may then use the S6a interface to request visiting UE 416's subscriber information from HSS 402. As
HSS 402 may receive the subscriber information request and retrieve the subscriber information for visiting UE 416. HSS 402 may then generate and send a subscriber information response in stage 616. The subscriber information response may include visiting UE 416's subscriber information.
AMF 408 may receive the subscriber information request and then perform an attach procedure for visiting UE 416 in stage 416. For example, AMF 408 may act as an MME and perform 3GPP the attach procedure specified in 3GPP TS 23.401, clause 5.3.2.1, step 5a. AMF 408 may then configure the inter-core network roaming connection for visiting UE 416, described in detail later.
As message sequence chart 700 shows, AMF 408 and NRF 406 may perform stages 702-708 in the same manner as stages 602-608 from message sequence chart 600 in
Accordingly, in stage 712 AMF 408 may decide to identify an AMF that can support the EPC interface. In the example shown in
In any case, AMF 408 may identify another AMF that supports an S6a interface with HSS 402. AMF 408 may then redirect visiting UE 416 to that AMF in stage 716. For example, AMF 408 may send to visiting UE 416 control signalling that redirects visiting UE 416 to the other AMF. Alternatively, AMF 408 may redirect visiting UE 416 within the network (e.g., via signalling with NG-RAN 414 or communication signalling between AMFs) without visiting UE 416 knowing that it has been redirected to the other AMF.
The other AMF may then, for example, either obtain visiting UE 416's subscription information from HSS 402 or reject visiting UE 416's registration request. In an example where the other AMF obtains the subscription information from HSS 402, the other AMF may perform stages 602-616 of message sequence chart 600 in
In the case where the other AMF rejects visiting UE 416's registration request, the other AMF may redirect the visiting UE to the visiting mobile network's EPC. That procedure is described below in stage 812 of message sequence chart 800 of
As
In some aspects, AMF 408 may be configured either to accept visiting UE 416's registration request or to redirect it based on operator policy. For example, AMF 408 may be preconfigured with operator policy that allows inter-core network roaming (where AMF 408 would use the procedure of message sequence chart 600 or 700) or with operator policy that forbids inter-core network roaming (where AMF 408 would use the procedure of message sequence chart 800). Thus, after receiving the NF service response from NRF 406 and/or determining that the target NF is an EPC NF, AMF 408 may determine whether to accept visiting UE 416's registration request based on the preconfigured operator policy.
In some aspects, visiting UE 416's home mobile network may allow or forbid UEs from performing inter-core network roaming. For example, HSS 402 may be preconfigured with these permissions. When AMF 408 (or another AMF, like in
In some aspects, once AMF 408 determines that a particular home mobile network (by HPLMN ID) supports EPC, AMF 408 may specify that information in later NF Service discovery requests. For example, AMF 408 may send an NF Service discovery request for the HPLMN ID of visiting UE 416's home mobile network, and the response from NRF 406 may specify that the home mobile network supports EPC. Then, if AMF 408 requests from NRF 406 an NF for that same HPLMN ID (e.g., for SGW or PGW selection in that home mobile network), AMF 408 may send an explicit request saying that it wants to discover an NF in the home mobile network and an express indication that it is requesting an EPC NF.
Accordingly, some examples in
This disclosure will use
In one HR roaming example using
In another HR roaming example using
AMF 408 may alternatively configure an LBO roaming connection for visiting UE 416. For LBO roaming, the visited mobile network may directly provide an external data connection to visiting UE 416 (e.g., without routing user-plane packets first to visiting UE 416's home mobile network). For example, UPF 412 may provide a connection to external data networks for visiting UE 416, and may route user-plane packets to and from visiting UE 416 on the path between (NG-RAN 414)-(UPF 412). AMF 408 may configure this LBO roaming connection by setting up NG-RAN 414 and UPF 412 to do this user-plane packet routing. The user-plane routing will be between NG-RAN 414 to UPF 412 to the internet, and the control plane routing will be between NG-RAN 414, AMF 408, SMF 410, and UPF 412.
In the examples of
In another example, AMF 408 may still use NRF 406 to determine that the target NF is an EPC NF and that AMF 408 should use the S6a interface. However, instead of sending Diameter messages directly to HSS 402, AMF 408 may send the Diameter messages to a Service Communication Proxy (SCP; also known as the Delegated Discovery function). The SCP may then forward the message to HSS 402 on behalf of AMF 408 (e.g., forward a subscriber information request). The SCP may similarly forward messages from HSS 402 to AMF 408 (e.g., forward a subscriber information response). The general procedure for stages 610-616 in message sequence chart 600 will remain the same except for the SCP sitting between AMF 408 and HSS 402.
The SCP may then determine that the target NF is an EPC NF (specifically, HSS) in stage 904. In some aspects, the SCP may be preconfigured (via O&M) with information identifying the HPLMN ID as an EPC. In other aspects, the SCP may query NRF 406 with an NF Service discovery request that requests information about the target NF (e.g., as in stages 504-508). The NF Service discovery response may then identify that the target NF is an HSS.
In the first option (“Option 1”), the SCP may translate the HTTP message to Diameter in stage 906. The SCP may then send a subscription information request (Diameter) to HSS 402 in stage 908 and response received from HSS 402 (in Diameter) is sent to AMF 408 (in HTTP messages). For example, in this case, the SCP seen by HSS 402 as a MME function and UDM as an AMF function. The protocol translation component (e.g., translation Diameter to HTTP (vice versa) or GTP to HTTP (vice versa) can be part of the SCP or can be outside of the SCP. If it is outside the SCP, then sends all the HTTP message to this component and this component translate to respective protocol and sends to the target NF directly or indirectly (via SCP).
In the second option (“Option 2”), the SCP may reject AMF 408's request in stage 910 (Nudm_UECM_Registration_Reject). Along with that rejection, the SCP may include HSS 402's address (e.g., FQDN) and an EPC indication specifying that the target NF is an EPC NF).
AMF 408 may thus determine that the target NF is an EPC NF based on the information in the rejection. AMF 408 may therefore decide to use Diameter messages to request and receive the subscription information for visiting UE 418. AMF 408 may generate and send a subscription information request (Diameter) in stage 912. In some aspects, AMF 408 may send the subscription information request directly to HSS 402. In other aspects, AMF 408 may send the subscription information to the SCP, which may forward the subscription information request to HSS 402. HSS 402 may respond by sending back the subscription information for visiting UE 418, either directly to AMF 408 or by routing it via the SCP.
With the aspects described above, a 5GC core network may support inter-core network roaming for visiting UEs whose home mobile networks only support EPC. Visiting UEs may therefore be able to use the visited mobile network's NR radio access network, thus enjoying higher data speeds and more flexibility.
In some aspects, the network functions (e.g., EPC and 5GC NFs/Services) described in this disclosure may be structurally configured like servers. For example, one or more of network functions 402-412 may include one or more processors configured to execute program code that defines its respective operations as described above. These one or more processors may retrieve that program code from a memory. In some aspects, one or more of network functions 402-412 may be implemented on a single processor or a co-located set of processors. In other aspects, one or more of network functions 402-412 may be implemented virtually, and may be executed across multiple separate processors using network function virtualization. From future perspective and could native design, some NFs may have one or more services. These services can run and manage independently in virtual or physical networks. It is therefore possible that there will no longer be NF concepts, but only network services (e.g., like IT companies). Aspects of this disclosure may also be implemented as software this manner. In some aspects, network functions 402-412 may include, or be executed on, one or more processors that work together with hardware logic circuitry (e.g., any type of specialized hardware, such as an application specific integrated circuit (ASIC)) to perform processing functions.
While this disclosure has described specific aspects, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the aspects of this disclosure as defined by the appended claims. The scope is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19173865.7 | May 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/062400 | 5/5/2020 | WO | 00 |
