Patent Description:
Currently core network architecture for the <NUM>th Generation System (5GS) such as new radio (NR) has been proposed. <FIG> shows a high level architecture of <NUM> core network. As shown in <FIG>, <NUM> core network (CN) may comprise a plurality of network functions (NF) such as AMF (Access and mobility Function), SMF (Session Management Function), AUSF (Authentication Service Function), UDM (Unified Data Management), PCF (Policy Control Function), AF (Application Function), NEF (Network Exposure Function), UPF (User plane Function) and NRF (NF Repository Function).

NF Repository Function (NRF) supports the following functionality:.

The NF service discovery is implemented by using the NRF. The NF selection consists in selecting one NF instance among the NF instance(s) discovered during the NF service discovery. The NF selection is implemented by the requester NF, e.g. the SMF selection is supported by the AMF.

For the NRF to properly maintain the information of available NF instances and their supported services, each NF instance informs the NRF of the list of NF services that it supports and other NF instance information, which is called NF profile. The typical information of NF profile could be, as per TS <NUM>:.

NF profiles comprises both static and dynamic information for NF, and NF profiles are stored in corresponding NRF.

Registration service enables NF service provider to register its NF profile e.g. supported NF services and other NF instance information in NRF and make it available to be discovered by other NF(s); Discovery service enable NF service consumer to discover the service provided by NF service provider by query the NRF; Depending on the requesting NF and the target NF, different input parameters is included in the discovery request then enable NRF to find a target NF that registered in NRF can serves the requesting NF best.

3GPP defines two types of NRF hierarchy:.

In the Network Slicing scenario, multiple NRFs can be deployed at different levels based on network implementation:.

In the context of roaming, multiple NRFs may be deployed in the different networks:.

It can be expected that NF(s) will make a discovery request including the discovery parameters - to find the target NF(s). In 3GPP TS29. <NUM> Release <NUM>, the specific discovery parameters are defined as follows.

<CIT> discloses a method and apparatus that uses network slicing. The apparatus receives a predetermined request from a UE, selects a single network slice instance to be allocated to the UE from among a plurality of network slice instances in the apparatus in response to the request, selects a single network function instance to be allocated to the UE from among a plurality of network function instances included in the selected network slice instance. The network slice instance is in an instantiated form of a network slice that includes at least one network function and resource for providing a network service having a predetermined capability and characteristic to the UE.

<CIT> A discloses a user equipment registration method for network slice selection, a network controller and a network communication system are provided. The method includes: receiving a registration request of a UE; in response to receiving the registration request including slice selection information, determining whether having a capability for serving the UE according to the slice selection information, so as to transmit a first network function discovery request including the slice selection information or transmit a second network function discovery request for searching a target AMF; and selecting a network function for serving the UE according to a network function discovery response to perform a registration setting operation after receiving the network function discovery response corresponding to the first network function discovery request, or transmitting an interface connection release message to an access node after receiving another network function discovery response corresponding to the second network function discovery request.

The non-patent literature document <NPL>, discloses that the NRF in serving PLMN identifies NRF based on the Remote PLMN ID, and it invokes "NF Discovery" service from the NRF of the remote PLMN according the procedure in Figure <NUM>. <NUM>-<NUM> to get the expected NF instance (s) or NF service deployed in the remote PLMN. As the NRF in the serving PLMN triggers the "NF Discovery" on behalf of the NF service consumer, the NRF in the serving PLMN sha/<NUM> not replace the information of the NF service consumer, i.e. NF service consumer ID, in the Discovery Request message it sends to the NRF in remote PLMN. Due to roaming agreements and operator policies, the NRF in the remote PLMN authorize the request and may provide information of the IP address or the FQDN of aset of the discovered NF instance(s) or of the specific NF service to the NRF in the serving PLMN. The NRF in serving PLMN provides the information e.g. FQDN and IP address, of a set of the discovered NF lnstance(s) or a specific NF service in NF Service Discovery Response message.

Various embodiments of the present disclosure mainly aim at providing methods, apparatuses for service discovery. Other features and advantages of embodiments of the present disclosure will also be understood from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the present disclosure.

In a first aspect of the disclosure, there is provided a method implemented at a primary Network-Function Repository Function, NRF, in a communication network, wherein the communication network comprising at least one primary NRF and at least one secondary NRFs, the method comprising: receiving a discovery request from a first secondary NRF, wherein the discovery request comprises a service query information for a target Network Function, NF, obtaining an target NF information, providing the target NF information to the first secondary NFR, wherein obtaining target NF information comprises: sending the discovery request to at least one of other secondary NRFs; and receiving a response from at least one of other secondary NRFs, wherein the response comprises an indication of whether the other secondary NRFs, contains the target NF information; and if the indication represents that the other secondary NRF contains the target NF information, the response further comprises the target NF information and/or the information of the other secondary NRF, the method further comprising: receiving registration information from one or more secondary NRFs; sending the discovery request to at least one of other secondary NRFs, and wherein the obtaining target NF information is based on the registration information; maintaining routing table information for mapping the information of the secondary NRFs; sending the discovery request to at least one of other secondary NRFs and the information of NFs which are registered in the corresponding NRF; and updating the routing table based on the registration information.

In a second aspect of the disclosure, there is provided a method implemented at a secondary Network-Function Repository Function, NRF, in a communication network, wherein the communication network comprising the primary NRF and at least one secondary NRFs, the method comprising: receiving a discovery request from a first Network Function, NF, wherein the discovery request comprises a service query information for a target NF; obtaining target NF information; providing the target NF information to the first NF, the method further comprising: determining if the secondary NRF contains the target NF based on the service query information, if the secondary NRF contains the target NF, sending the target NF information to the first NF, if the secondary NRF doesn't contain the target NF, forwarding the discovery request to the primary NRF, the method further comprising: receiving register request from the NF, wherein the register request comprises NF profile of the NF; updating NF profile of the secondary NRF; and sending registration information to the primary NRF, wherein the registration information comprises a record for mapping the information of the secondary NRF and the information of NF which is registered in the secondary NRF.

In a fourth aspect of the disclosure, there is provided an apparatus for a primary Network-Function Repository Function, NRF, comprising: a processor; and a memory coupled to the processor, said memory containing instructions executable by said processor, whereby said apparatus is is operative to perform method steps of the first aspect indicated above.

In a fifth aspect of the disclosure, there is provided an apparatus for a secondary Network-Function Repository Function, NRF, comprising: a processor; and a memory coupled to the processor, said memory containing instructions executable by said processor, whereby said apparatus is operative to perform the method steps of the second aspect indicated above.

Some embodiments of the disclosure may have the following advantage. The invention enables NF in <NUM> network to make service discovery across different regions. Even though some embodiments have been summarized above, the claimed subject matter is defined in the attached claims.

As used herein, the term "network" refers to a network following any suitable communication standards, such as LTE-Advanced (LTE-A), LTE, Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), NR and so on. Furthermore, the communications between a terminal device and a network device in a wireless communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the third generation (<NUM>), the fourth generation (<NUM>), <NUM>, the future fifth generation (<NUM>) communication protocols such as NR, wireless local area network (WLAN) standards, such as the IEEE <NUM> standards; and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax) and/or any other protocols either currently known or to be developed in the future.

The term "network function (NF)" refers to any suitable function which can be implemented in a network device of a wireless/wired communication network via which a terminal device can access the network and receives services therefrom. For example, in <NUM> network, the NF may comprise AMF, SMF, AUSF, UDM, PCF, AF, NEF, UPF and NRF. It is noted that the NF may comprise different NFs depending on a specific type of network.

The term "terminal device" refers to any end device that can access a wireless communication network and receive services therefrom. By way of example and not limitation, the terminal device refers to a mobile terminal, user equipment (UE), or other suitable devices. The UE may be, for example, a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a portable computer, an image capture terminal device such as a digital camera, a gaming terminal device, a music storage and a playback appliance, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet, a wearable device, a personal digital assistant (PDA), a portable computer, a desktop computer, a wearable terminal device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a USB dongle, a smart device, a wireless customer-premises equipment (CPE) and the like. In the following description, the terms "terminal device", "terminal", "user equipment" and "UE" may be used interchangeably. As one example, a terminal device may represent a UE configured for communication in accordance with one or more communication standards promulgated by the 3GPP (3rd Generation Partnership Project), such as 3GPP' LTE standard or NR standard. As used herein, a "user equipment" or "UE" may not necessarily have a "user" in the sense of a human user who owns and/or operates the relevant device. In some embodiments, a terminal device may be configured to transmit and/or receive information without direct human interaction. For instance, a terminal device may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the wireless communication network. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but that may not initially be associated with a specific human user.

As yet another example, in an Internet of Things (IOT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

Although the two types of the NRF hierarchy in 3GPP, another type of NRF hierarchy (as shown in <FIG>) is clearly needed by major operators who normally divided their large network into small subnetworks based on geography area for better management.

The network can be divided into several regions, for example, based on the province border. In <FIG>, the network is divided into <NUM> regions, region A-C. In every region, there is a corresponding NRF, and at least one NF, such as AMF, SMF, UPF, NSSF (Network Slice Selection Function), AUSF, UDM, UDR, etc. And the NRF maintains the NF profile of available NF instances and their supported services.

It can be expected that in the same region, NF(s) will discover and invoke service towards NF(s) though the NRF. But when the NF(s) in the same region can't support the service that the source target NF(s) request, then NF(s) need to discover and invoke service towards NF(s) in other regions, it is then expected that PLMN NRF (here also called central NRF) and/or the other region NRF will help on the service discovery. This kind of cross-region, service discovery can happen in the following scenario:.

Accordingly, the query parameters such as FQDN, URI, IP address, TAI, cell ID, node ID, UE IP address, UE identity e.g. SUPI (Subscription Permanent Identifier), GPSI (Generic Public Subscription Identifier), group ID, or routing ID can be specific per region.

NRF is important for setting up the signaling path in Control Plane, as every NF need query NRF to find a proper next hop NF (or NF service) instance per traffic context. However, in the scenario of network deployment based on geography area (or other similarly independent deployment realm, e.g. slice, domain) showed above, for cross region service discovery (or service discovery among other similar independent deployment realm, e.g. slice, domain), it is not clear, how the regional NRF can find the proper peer regional NRF to discover the target NF(s). In particular, it is hard for source NRF to determine the target NRF, when different input parameters are included in the discovery request.

To overcome or mitigate at least one of above mentioned problems or other problems or provide an alternative solution, the embodiments of the present disclosure propose a solution for service discovery.

Reference is now made to <FIG>, the communication system <NUM> comprises at least one central NRF <NUM> and at least one regional NRF (as Regional NRF #<NUM>, Regional NRF #<NUM>, Regional NRF #<NUM>,. , Regional NRF #n). In every area (as region A), there is a regional NRF (as Regional NRF #<NUM>) and at least one NF (as NF X in region A). The NF in the specific area register its NF profile to its own regional NRF, for example, NF X registers its NF profile to regional NRF #<NUM>. The regional NRF maintains the NF profile of available NF instances (as NF X) and the supported services.

Reference is now made to <FIG>, which shows flowcharts of methods according to embodiments of the present disclosure. The methods may be implemented at a primary NRF (the Central NRF shown in <FIG>) such as PLMN NRF.

As shown in <FIG>, the method <NUM> may comprise: receiving a discovery request from a first secondary NRF, wherein the discovery request comprises a service query information for a target Network Function, NF, at block <NUM>, and obtaining target NF information at block <NUM>, and providing the target NF information to the first secondary NRF at block <NUM>. Before block <NUM>, the regional NF (e.g. NF X) need a certain type of service, so it sends discovery request with service query parameters to regional NRF it registered (e.g. Regional NRF #<NUM>) to request the service. And then the regional NRF will check the information stored in itself to find out if there is any NF registered in it can provide this service. If there is a target NF can provide the service, then the regional NRF#<NUM> will send the target NF information to NF X. But if there is no NF registered in the NRF can provide such type of service, then the regional NRF#<NUM> will forward the discovery request with service query parameters to another NRF, e.g. the central NRF, and at block <NUM> the central NRF receives the discovery request.

In another alternative embodiment, the central NRF may receive the discovery request from a NF, e.g. NF X directly. And then the central NRF performs the following steps (step <NUM> and <NUM>).

At block <NUM>, the central NRF obtains the target NF information. The target NF information can be obtained in various ways.

In an embodiment, the primary NRF (central NRF) check the information stored in itself and determine if it contains the target NF information based on the service query information. If it contains the target NF information (NF Y) mapping, it will send the target NF information (NF Y) and/or the information of the NRF (regional NRF #<NUM>) in which the target NF is registered to the first secondary NRF (regional NRF #<NUM>). If there is no target NF information found, the central NRF may send the discovery request to at least one of other secondary NRFs (Regional NRF #<NUM>, Regional NRF #<NUM>,. , Regional NRF #n).

In another embodiment, the primary NRF (central NRF) may directly send the discovery request to at least one of other secondary NRFs (Regional NRF #<NUM>, Regional NRF #<NUM>,. , Regional NRF #n) without check in the information stored in itself; and receives a response from at least one of other secondary NRFs.

As the first embodiment of obtaining the target NF information, the central NRF sends the discovery request to the other regional NRFs (e.g. Regional NRF #<NUM>, Regional NRF #<NUM>,. , Regional NRF #n ), and then the regional NRFs will check the information stored in itself to find if it contains the NF (the target NF) that can provide the service to the NF X (here every NF in all regions has registered its NF profile in the corresponding NRF before). The discovery request can be sent to other reginal NRFs in different ways: broadcasting, polling, and multicasting, etc..

As the broadcasting, the central NRF broadcasts the discovery request to all regional NRFs, then the regional NRF will check if it contains the target NF, and make a response.

As the polling, the central NRF sends the discovery request to one regional NRF at first time, and then the regional NRF will check if it contains the target NF, and make a response, if the response indicates the regional NRF doesn't contain the target NF, then then central NRF will send the discovery request to another regional NRF,. , until the central NRF receives the response indicating that the regional NRF contains the target NF.

As the multicasting: in one example, the central NRF selects one or more NRFs from the other secondary NRFs based on the service query information, and then multicasts the discovery request to the regional NRFs selected (for example: the service query parameter can be linked to a certain scope of region areas, and the central NRF selects all NRFs which are serving those areas). In another example, the central NRF may maintain a routing table for mapping the service query information and the target NF information and/or the information of the regional NRF, the routing table is updated based on the response from the regional NRF; and the regional NRF can also register itself in the central NRF with its address, and the NRF property (e.g. region information: region ID, group ID etc). For example, when a regional NRF checks that it contains the target NF, it includes the target NF information and/or the information of itself (this regional NRF) into the response, and sends the response to the central NRF, after the central NRF receives the response, it will update the routing table, and then when the central NRF received a discovery request from the regional NRF, such as Regional NRF #<NUM>, it will select one or more regional NRFs based on the routing table and/or the service query information.

After the central NRF obtains the target NF information, the central may store information that mapping the service query parameters and the target NF information, and/or information of another NRF e.g. regional NRF #<NUM>. So that the central NRF can learn from the previous requests, then it can make a quick response when it receives the discovery request including the same service query parameters.

As the second embodiment of obtaining the target NF information, the central NRF receives registration information from one or more secondary NRFs, and the target NF information is obtained based on the registration information. In an embodiment, the central NRF maintains routing table information for mapping the information of NRFs and the information of NFs which are registered in the corresponding NRF. In one embodiment, a blank routing table is created, and one or more regional NRF register itself to the central NRF with its registration information, wherein the registration information comprises a record for mapping the information of the regional NRF and the information of NF which is registered in the regional NRF. After the central NRF receives the registration information from the regional NRFs, it will update the routing table based on the registration information.

In one embodiment, the registration information may comprise at least part of the NF profile of the regional NRF, wherein the NF profile of the regional NRF comprising: NRF's profile and NRF specific information; wherein the NRF's profile comprising at least part of following information of the NRF:
NF instance ID, NF type; service name, PLMN ID, FQDN, S-NSSAI, NSI, IP address, region ID, ECGi, NCGI, TAI; DNN, group ID, SUPI ranges, GPSI ranges, external Group Identifiers Ranges; Data Set ID; routing ID of SUCI;
The NRF specific information comprising at least part of the information of the NFs which are registered in the regional NRF. For example, one UDM and one UPF have registered in the NRF, then the NRF specific information comprises the NF file of the UDM and the NF file of the UDM.

The routing table may comprise one or more of the following information:.

And after receiving the discovery request from the regional NRF #<NUM>, in an embodiment, if the routing table contains the NF file (or part of NF file) of the NF registered in the NRF, the central NRF may determine the target NF based on the routing table, and then send the target information to regional NRF #<NUM>. In another embodiment, if the routing table doesn't contain the NF file of the NF registered in the NRF, the central NRF can't get the target NF information, the central NRF may select the one or more regional NRFs from the other regional NRFs (Regional NRF #<NUM>, Regional NRF #<NUM>,. , Regional NRF #n) based on the routing table information, and then sends the discovery request the regional NRFs selected. The regional NRFs will check the information stored in itself to find if it contains the NF (the target NF) that can provide the service to the NF X, and send response to central NRF.

In an embodiment, the central NRF may broadcast the routing table to the regional NRF (Regional NRF #<NUM>, Regional NRF #<NUM>, Regional NRF #<NUM>,. , Regional NRF #n), so that the regional NRF can make a quick response when the similar discovery request comes next time.

The response from the regional NRF (Regional NRF #<NUM>, Regional NRF #<NUM>,. , Regional NRF #n) to central NRF may comprise different information. For example, if the regional NRF find it contains the target NF, the response may comprise the target NF information, or may comprise the indication of whether it contains the target NF information (e.g.: OK), or may comprise the both information above. If the regional NRF find it doesn't contain the target NF, the response may comprise the indication of whether it contains the target NF information (e.g.: No found), or may not response to NRF. And the target NF information may comprise the NF profile of the target NF (NF Y).

After the central obtains the target information, it will send the response including the target NF (NF Y) information to the regional NRF (regional NRF #<NUM>). In another embodiment, the response may further comprise information of the corresponding regional NRF (regional NRF #<NUM>), such as the address of regional NRF #<NUM>.

<FIG> shows a flowchart of method <NUM> according to an embodiment of the present disclosure. As shown in <FIG>, The methods may be implemented at a first secondary NRF (source NRF as regional NRF #<NUM> shown in <FIG>).

As shown in <FIG>, the method <NUM> may comprise: receiving a discovery request from a first Network Function, NF, wherein the discovery request comprises a service query information for a target NF at block <NUM>; obtaining target NF information at block <NUM>; providing the target NF information to the first NF at block <NUM>.

Before block <NUM>, a source NF (NF X in region A) need a service from other NF, so NF X triggers a discovery request including the service query parameters.

As the discovery request, it refers to at least the requests of Nnrf_NFDiscovery and Nnrf_NFManagement, OAuth2 Authorization as defined in 3GPP <NUM>, and correspondingly, discovery response refers to at least, the response of the above-mentioned requests.

As the service query parameters, it refers the filtering criteria that is included in the discovery request; it shall at least include the URI query parameters of Nnrf_NFDiscovery service and subcriptionData of Nnrf_NFManagement service as defined in 3GPP <NUM>. The service query parameters may comprise at least one of the following: NFType, service Name, NF SetID, PLMN ID, FQDN, URI, IP address, NSSAI, NSI, DNN, TAI, cell ID (E-UTRAN Cell Global Identifier, ECGI, NR Cell Global Identifier, NCGI), NF instance ID, AMF region ID, AMF set ID, GUAMI, UE IP address, UE identity (e.g. SUPI, GPSI, group ID), or routing ID of SUCI etc..

NF X sends the discovery request including the service query parameters to the regional NRF #<NUM> (regional NRF #<NUM> and the NF X are in the same region A), and the regional NRF #<NUM> will receive the discovery request at the block <NUM>.

At block <NUM>, the regional NRF #<NUM> obtains target NF information. In an embodiment, the regional NRF #<NUM> may determine if it contains the target NF based on the service query parameters. The regional NRF #<NUM> will match the NF profile of the NF registered in it, and if one of the NF profile of the NF can match the service query parameters, then the regional NRF #<NUM> will send the target NF information to NF X, then the flow will stop. But if the regional NRF #<NUM> can't find the target NF, then it will forward the discovery request to another NRF, e.g. the central NRF. Then the central NRF will find the target with the above-mentioned method, if the central NRF find the target NF (NF Y), it will send the target information to the regional NRF #<NUM>, then the regional NRF #<NUM> will send the target NF information to NF X. The target information may be the NF file of the target NF, or the target information may be part of the NF file or other information that could make NF X reach NF Y directly or indirectly.

In an embodiment, the regional NRF #<NUM> may storing the record that mapping the service query parameters and the target NF information, and/or information of another NRF e.g. regional NRF #<NUM>. So that the regional NRF #<NUM> can learn from the previous requests, then it can make a quick response when it receives the discovery request including the same service query parameters.

In an embodiment, the regional NRF #<NUM> may have knowledge of the exact target regional NRF contain the target NF, it can forward the discovery request directly to the target regional NRF. For example, the regional NRF #<NUM> is pre-configured to store the information that the regional NRF #<NUM> contains the target NF (NF Y) which can provide service to NF X, then regional NRF #<NUM> will forward the discovery request directly to the target regional NRF #<NUM>. And then after the regional NRF #<NUM> confirm that it contains the target NF Y, it will send the NF Y information to regional NRF #<NUM>, and regional NRF #<NUM> will send the NF Y information to NF X. Therefore, a communication link can be established between NF X and NF Y, so that NF Y can provide the service to NF X.

In an embodiment, the regional NRF may receive register request from the NF, wherein the register request comprising NF profile of the NF, then update NF profile of the itself, and send registration information to the central NRF, wherein the registration information comprises the NF profile of the regional NRF, e.g. including the mapping information of the secondary NRF and the information of NF which is registered in the regional NRFs. Then the central NRF will know the NF file of all the regional NRF so that it can select the specific NRFs to multicast when it receives a discovery request.

<FIG> shows a flowchart of method <NUM> according to an embodiment of the present disclosure. As shown in <FIG>, The methods may be implemented at a secondary NRF (as regional NRF #<NUM>, #<NUM>,. , #n shown in <FIG>).

As shown in <FIG>, the method <NUM> may comprise: receiving a discovery request from a NRF (e.g. central NRF in <FIG> ) , wherein the discovery request comprises a service query information for a target NF at block <NUM>; determining if the secondary NRF contains the target NF based on the service query information at block <NUM>; sending response to the primary NRF at block <NUM>.

As mentioned-above, the regional NF (e.g. NF X) need a certain type of service, so it sends discovery request with service query parameters to regional NRF it registered (e.g. Regional NRF #<NUM>) to request the service. And then the regional NRF will check the information stored in itself to find out if there is any NF registered in it can provide this service. If there is no NF registered in the NRF can provide such type of service, then the regional NRF#<NUM> will forward the discovery request with service query parameters to the central NRF, and the central NRF receives the discovery request. And then central NRF will send the discovery request to the other regional NRF (one or more of regional NRF #<NUM>, #<NUM>,. And the regional NRF may receive a discovery request from a primary NRF (central NRF), wherein the discovery request comprises a service query information for a target NF at block <NUM>.

And in another embodiment, the communication network may do not contain the central NRF, and all the regional NRF may be equal. In this scenario, the regional NRF may receive the discovery request from another regional NRF (e.g. regional NRF #<NUM>), and correspondingly after the regional determine it contains the target NF shown below in block <NUM>, it will send response to regional NRF #<NUM>.

At block <NUM>, the regional NRF determine if it contains the target NF based on the service query information. The regional NRF determines if it contains the target NF by matching the service query information and NF profile of NFs registered in the secondary NRF. If there is no NF file in the regional NRF can match the service query information, the regional NRF may response including the indication of "No found" to the central NRF, or the regional NRF may don't make a response.

If the NF profile of the NF can match the service query information, determine that the NF is the target NF, and send response including the target NF information (NF Y) to the primary NF, and the response may further comprise the indication of finding the target NF (such as "OK"). The target information maybe the NF file of the target NF, maybe be part of the NF file or other information that could make NF X reach NF Y directly or indirectly.

Then the central may forward the target information to the regional NRF #<NUM>, and NRF #<NUM> forward the target information to NF X. Therefore, a communication link can be established between NF X and NF Y, so that NF Y can provide the service to NF X.

In an embodiment, the regional NRF may receive register request from the NF, wherein the register request comprising NF profile of the NF, then update NF profile of the itself, and send registration information to the central NRF, wherein the registration information comprises the NF profile of the regional NRF, e.g. including the mapping information of the secondary NRF and the information of NF which is registered in the regional NRF. Then the central NRF will know the NF file of all the regional NRF so that it can select the specific the NRFs to multicast when it receives a discovery request.

<FIG> shows a flowchart of one method according to an embodiment of the present disclosure. As shown in <FIG>, the method is implemented in the communication system. For some parts which have been described in the above embodiments, detailed description thereof is omitted here for brevity.

At 701a, the central NRF (PLMN NRF) may configure regions NRF list URL for forwarding the service request to the regional NRF(s), and at 701b, the regional NRF may register itself in the central NRF with its address, and the NRF property like region information region ID, group ID.

At <NUM>, the NF X (a service consumer, e.g. AMF) triggers discover "NF Y" (a service producer, e.g. UDM) with the service query parameters towards its own regional NRF, i.e. regional NRF #<NUM>; Within the discovery request, there are the service query parameters e.g. SUPI.

At <NUM>, The regional NRF #<NUM> can not find the NF profile of NF Y, as NF Y is not located and registered in this region.

At <NUM>, the regional NRF #<NUM> then forward the discovery request to the Central NRF with all the service query parameters. Optionally if regional NRF #<NUM> have knowledge of the exact target regional NRF matching the service query parameters, e.g. got from a previous request. The regional NRF #<NUM> can then forward the discovery request directly to the target regional NRF.

After receiving the discovery request, the central NRF may optionally check the information stored in itself and determine if it contains the target NF information based on the service query information. If it contains the target NF information (NF Y), it will send the target NF information (NF Y) and/or the information of the NRF (regional NRF #<NUM>) in which the target NF is registered to the first secondary NRF (regional NRF #<NUM>). If there is no target NF information found, goes to step <NUM>.

At <NUM>, the central NRF checks the input service query parameters and determines the next hop NRF(s) to be queried. Multiple regional NRFs can be selected. The selection can be based on the service query parameters and or the available routing table information. For example, the service query parameter can link to a certain scope of region areas. The PLMN NRF then selects all NRFs serving those areas.

At <NUM>, the central NRF forwards the discovery request to those regional NRF(s).

At <NUM>, the regional NRF(s) checks the service query parameters and determine whether it contains the requested NF. If the regional NRF does not contain NF profile of NF Y, it response not found back to the central NRF at 712a; If the regional NRF contains NF profile of NF Y, it response successfully back to the central NRF;
At <NUM>, the central NRF then forwards the successful result and NF profile of NF Y back to the regional NRF #<NUM>. Optionally the central NRF can also return the address of the target regional NRF #<NUM>, it will help to build a routing table in regional NRF #<NUM> and enable a direct query between regional NRF #<NUM> and #<NUM> when the next time similar request comes. Optionally the central NRF can create or update a routing table information, recording the mapping between, the input service query parameter, the target NF of query, and the target regional NRF. It will help to a fast response when the next time similar request comes. central NRF may also trigger a broadcast to distribute such routing table information to all regional NRF(s).

At <NUM>, the regional NRF #<NUM> then response the successful result and NF profile of NF Y back to NF X. Optionally, if the regional NRF triggers the multicast discovery, the regional NRF can create a local information, recording the mapping between, the input service query parameter, the target NF of query, and the target regional NRF. It will help to a fast response when the next time similar request comes.

At <NUM>, NF x then set up communication with NF Y.

<FIG> shows a flowchart of another method according to an embodiment of the present disclosure. As shown in <FIG>, the method is implemented in the communication system. For some parts which have been described in the above embodiments, detailed description thereof is omitted here for brevity.

At <NUM>, a NF, e.g. NF Y, registers itself in the its own region NRF, with its NF profile.

At <NUM>, The regional NRF, checks the NF profile and determine a routing information record for its own region. The routing information record is built upon, the NF Y's NF profile and its attributes (as defined in 3GPP TS <NUM>), the regional NRF identifier and address, and the region information e.g. region ID.

At <NUM>, The regional NRF registers itself in central NRF, with its NF profile and routing information record. For example, routing information record can be part of the NRF's NF profile. Similar procedure repeated for all regional NRFs to register themselves in central NRF.

At <NUM>, The central NRF then creates or updates a routing table information, based on the routing information record registered by regional NRFs.

At <NUM>, the central NRF may also trigger a broadcast to distribute such routing table information to all regional NRF(s).

At <NUM>, NF X (a service consumer, e.g. AMF), trigger discovery request to find NF Y (a service producer, e.g. UDM) towards its own region NRF, e.g. regional NRF #<NUM>. Within the discovery request, there are the service query parameters e.g. SUPI.

At <NUM>, the regional NRF #<NUM> cannot find the NF profile of NF Y, as NF Y is not located and registered in this region. Optionally if regional NRF #<NUM> have a routing table from previous request and have knowledge of the exact target regional NRF matching the service query parameters. The regional NRF #<NUM> can then forward the discovery request directly towards the target regional NRF.

At <NUM>, the regional NRF #<NUM> then forward the discovery request to the central NRF with the service query parameters.

At <NUM>, the central NRF checks the input service query parameters and determines the next hop NRF(s) to be queried. The selection can be based on the service query parameters and/or the available routing table information. For example, the service query parameter, SUPI, can link to SUPI range of a routing information record. The central NRF then selects the NRF associated with that routing information record.

At <NUM>, the central NRF forward the discovery request to the selected regional NRF.

At <NUM>, the regional NRF checks the service query parameters and determine whether it contains the requested NF. If the regional NRF does not contain NF profile of NF Y, it response not found back to the central NRF; if the regional NRF contains NF profile of NF Y, it response successfully back to the central NRF.

At <NUM>, the central NRF then sends the successful result and NF profile of NF Y back to it upstream, the regional NRF #<NUM>.

At <NUM>, the regional NRF #<NUM> then response the successful result and NF profile of NF Y back to NF x.

<FIG> illustrates a simplified block diagram of an apparatus <NUM> that may be embodied in/as central NRF according to an embodiment of the present disclosure. <FIG> illustrates an apparatus <NUM> that may be embodied in/as a first regional NRF according to an embodiment of the present disclosure. <FIG> illustrates an apparatus <NUM> that may be embodied in/as a regional NRF according to an embodiment of the present disclosure.

The apparatus <NUM> may comprise at least one processor <NUM>, such as a data processor (DP) and at least one memory (MEM) <NUM> coupled to the processor <NUM>. The apparatus <NUM> may further comprise a transmitter TX and receiver RX <NUM> coupled to the processor <NUM>. The MEM <NUM> stores a program (PROG) <NUM>. The PROG <NUM> may include instructions that, when executed on the associated processor <NUM>, enable the apparatus <NUM> to operate in accordance with the embodiments of the present disclosure, for example to perform the methods <NUM> and a part of methods <NUM>, <NUM>. A combination of the at least one processor <NUM> and the at least one MEM <NUM> may form processing means <NUM> adapted to implement various embodiments of the present disclosure.

The apparatus <NUM> comprises at least one processor <NUM>, such as a DP, and at least one MEM <NUM> coupled to the processor <NUM>. The apparatus <NUM> may further comprise a transmitter TX and receiver RX <NUM> coupled to the processor <NUM>. The MEM <NUM> stores a PROG <NUM>. The PROG <NUM> may include instructions that, when executed on the associated processor <NUM>, enable the apparatus <NUM> to operate in accordance with the embodiments of the present disclosure, for example to perform the methods <NUM> and a part of methods <NUM>, <NUM>. A combination of the at least one processor <NUM> and the at least one MEM <NUM> may form processing means <NUM> adapted to implement various embodiments of the present disclosure.

Various embodiments of the present disclosure may be implemented by computer program executable by one or more of the processors <NUM>, <NUM>, and <NUM>, software, firmware, hardware or in a combination thereof.

The MEMs <NUM>, <NUM> and <NUM> may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples.

The processors <NUM>, <NUM> and <NUM> may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors DSPs and processors based on multicore processor architecture, as non-limiting examples.

Although some embodiments are described in the context of an exemplary network shown in <FIG>, it should not be construed as limiting the spirit and scope of the present disclosure. The principle and concept of the present disclosure may be more generally applicable to other network architectures supporting Selective UP Activation and Deactivation.

Some embodiments may have the following advantage. All the sessions, the specified type of session(s), or the session(s) towards the specified data network name of the UE may be activated by the first NF based on corresponding, therefore the user experience and/or quality of service for these sessions may be improved.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of the corresponding apparatus described with the embodiment and it may comprise separate means for each separate function, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses), firmware (one or more apparatuses), software (one or more modules), or combinations thereof. For a firmware or software, implementation may be made through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the subject matter described herein, but rather as descriptions of features that may be specific to particular embodiments.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any implementation or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular implementations. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

Claim 1:
A method implemented at a primary Network-Function Repository Function, NRF (<NUM>), in a communication network, the method comprising:
receiving a discovery request from a first secondary NRF (NRF#<NUM>), wherein the discovery request comprises a service query information for a target Network Function, NF,
obtaining target NF information;
providing the target NF information to the first secondary NRF (NRF#<NUM>); wherein obtaining target NF information comprises:
sending the discovery request to at least one of other secondary NRFs (NRF#<NUM>); and
receiving a response from at least one of other secondary NRFs (NRF#<NUM>...n), wherein the response comprises an indication of whether the other secondary NRFs (NRF#<NUM>), contains the target NF information; and
if the indication represents that the other secondary NRF (NRF#<NUM>) contains the target NF information, the response further comprises the target NF information and/or the information of the other secondary NRF,
the method further comprising:
receiving registration information from one or more secondary NRFs;
sending the discovery request to at least one of other secondary NRFs (NRF#<NUM>...n), and wherein the obtaining target NF information is based on the registration information;
maintaining routing table information for mapping the information of the secondary NRFs (NRF#<NUM>...n);
sending the discovery request to at least one of other secondary NRFs (NRF#<NUM>... n) and the information of NFs which are registered in the corresponding NRF; and
updating the routing table based on the registration information.