Method and apparatus for attaching UE to non-terrestrial networks by pre fetching subscription data in a wireless communication system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Embodiments herein disclose methods to perform an attach procedure in a satellite communication by the MME (900). The method includes receiving a request message from a User Equipment (UE) (1000). Further, the method includes identifying that the UE (1000) has not been authenticated upon receiving the requested message as at least one UE detail is not available onboard the satellite (104).

Description

METHOD AND APPARATUS FOR ATTACHING UE TO NON-TERRESTRIAL NETWORKS BY PRE FETCHING SUBSCRIPTION DATA IN A WIRELESS COMMUNICATION SYSTEM

[0001] Embodiments disclosed herein relate to integrating a satellite component into a 3rdGeneration Partnership Project　(3GPP) architecture, and more particularly to systems and methods for adjusting user-to-network communication procedures in a fifth generation (5G) system to cater to a discontinuous nature of coverage provided by satellites.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in “Sub 6GHz” bands such as 3.5GHz, but also in “Above 6GHz” bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz (THz) bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] This disclosure relates to wireless communication networks, and more particularly to a terminal and a communication method thereof in a wireless communication system.

[0009] In accordance with an aspect of the disclosure,

[0010] The embodiments herein is to disclose methods and systems for adjusting user-to-network communication procedures in EPS and 5G systems to cater to the discontinuous nature of coverage provided by satellites.

[0011] An object of the embodiments herein is to perform an attach procedure in a satellite communication in a single operation.

[0012] An object of embodiments herein is to expedite a process of a user equipment's attachment to the network, when the network includes non-terrestrial radio access network.

[0013] An object of embodiments herein is to cater to the discontinuous nature of coverage provided by satellites and complete the same in fewer revolutions of a satellite around earth.

[0014] Another object of embodiments herein is to attach the UE to a Non-Terrestrial Network by sending a request message to an onboard satellite entity.

[0015] Another object of the embodiment herein is to attach the UE to the Non-Terrestrial Network, for a faster and reliable network when the feeder-link connectivity is restored, the satellite requests authentication and subscription data from an on-ground entity, using a pre-fetch flag to optimize data retrieval.

[0016] Another object of embodiments herein is to attach the UE to the Non-Terrestrial Network by initiating on-ground AMF authentication by contacting an Authentication Server Function (AUSF) with a store-and-forward indication, receiving necessary authentication data and registering with the Unified Data Management (UDM) and retrieving the UE's subscription data, to complete the attachment process efficiently in a non-terrestrial environment.

[0017] Another object of embodiments herein is to attach the UE to the Non-Terrestrial Network where the AMF and / or MME functionality is split into two network functions-partial hosted on the Satellite and partial hosted on ground, wherein the AMF and / or MME on-ground is responsible for communicating with the HSS and / or UDM, and for performing actions of attaching UE to the network.

[0018] An object of embodiments herein is to attach the UE to the Non-Terrestrial Network where the MME on-board satellite retrieves the authentication vectors and the subscription data of the UE in the single operation from the HSS on-ground, wherein the MME on-board satellite retrieves the subscription data of the UE immediately, before performing authentication with the UE.

[0019] An object of embodiments herein is to attach the UE to the Non-Terrestrial Network where the MME updates the HSS that the UE is authenticated and it holds valid context of the UE after receiving the 'attach complete' message in the scenario that an authentication vector and a subscription data are retrieved simultaneously.

[0020] An object of embodiments herein is to attach the UE to the Non-Terrestrial Network where the AMF (or partial functionality) on-board satellite retrieves the authentication vectors, from the AUSF on-ground, it immediately goes on to execute the AMF's registration into the UDM and retrieval of subscription data from the UDM, even before AMF on-board performs authentication with the UE.

[0021] Another object of the embodiments herein is to attach the UE to the Non-Terrestrial Network wherein the AMF updates the UDM / AUSF that the UE is authenticated in the serving network and it holds valid context of the UE after receiving the 'Registration Complete message', in the scenario that the authentication vectors and the subscription data are retrieved simultaneously.

[0022] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating at least one embodiment and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

[0023] Aspects of the disclosure are to address at least the above-mentioned problems and / or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide a terminal and a communication method thereof in a wireless communication system.

[0024] Embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the following illustratory drawings. Embodiments herein are illustrated by way of examples in the accompanying drawings, and in which:

[0025] FIG. 1 is a representation of simultaneous unavailability of Service and Feeder Links resulting in the problems described herein, according to existing arts;

[0026] FIG. 2 depicts a sequence representation of delayed attach procedure due to satellite movement & simultaneous unavailability of Service and Feeder Links in EPS system, according to existing arts;

[0027] FIG. 3 depicts a sequence representation of delayed registration procedure due to satellite movement & simultaneous unavailability of Service and Feeder Links in 5G system, according to existing arts;

[0028] FIG. 4 depicts a sequence representation of an example of an improved attach procedure in an EPS system, according to the embodiments as disclosed herein;

[0029] FIG. 5 depicts a flow-chart representation of a method for attaching a User Equipment to a Non-Terrestrial Network by a MME, according to the embodiments as disclosed herein;

[0030] FIG. 6 depicts a sequence representation of an example of improved registration procedure in 5G system, according to embodiments as disclosed herein;

[0031] FIG. 7 depicts an example scenario to perform an attach procedure of UE in a satellite communication of simultaneous unavailability of Service and Feeder Links, according to the embodiments as disclosed herein; and

[0032] FIG. 8 depicts various hardware components of the MME, according to the embodiments as disclosed herein.

[0033] FIG. 9 illustrates various hardware components of a base station, according to the embodiments as disclosed herein; and

[0034] FIG. 10 illustrates various hardware components of a UE according to the embodiments as disclosed herein.

[0035] Accordingly, the embodiments herein provide a method to perform an attach procedure in a satellite communication. The method includes receiving, by a Mobility Management Entity (MME), a request message from a User Equipment (UE). Further, the method includes identifying, by the MME, that the UE has not been authenticated upon receiving the requested message as at least one UE detail is not available onboard a satellite. Further, the method includes storing, by the MME, the request message. Further, the method includes triggering, by the MME, to perform Store and Forward (S&F) operation. Further, the method includes completing, by the MME, a Non-access stratum (NAS) procedure in a single operation.

[0036] In an embodiment, triggering, by the MME, to perform the S&F operation includes detecting, by the MME, when a feeder link is available, fetching, by the MME, at least one UE authentication detail from a Home Subscriber Server (HSS), pre fetching, by the MME, at least one UE subscription detail from HSS, and storing, by the MME, the at least one UE authentication detail and the at least one pre fetched UE subscription detail.

[0037] In an embodiment, the MME pre-fetches the at least one UE subscription detail from the HSS before executing an authentication procedure with the UE.

[0038] In an embodiment, completing the NAS procedure in the single operation includes detecting, by the MME, when a service link is available, performing, by the MME, an authentication procedure with the UE, executing, by the MME, remaining steps (defined in 5.3.2 3GPP TS 23.410) of the attach procedure with the at least one pre fetched UE subscription detail from the HSS, detecting, by the MME, when a feeder link is available, and indicating, by the MME, to the HSS whether the authentication procedure is successful.

[0039] In an embodiment, when the at least one UE detail is not available onboard the satellite, the MME does not complete the NAS procedure with an information currently available on the satellite due to: the MME does not have at least one of: a UE security context, a UE specific authentication vector, and a subscription information.

[0040] In an embodiment, the at least one UE authentication detail is at least one of: at least one of authentication vector and a key use to execute an authentication procedure.

[0041] In an embodiment, the at least one UE subscription detail is a UE subscription information stored at an HSS.

[0042] In an embodiment, the MME is at least one of: an onboard MME and a ground MME.

[0043] Accordingly, the embodiments herein provide an MME including a UE attaching procedure handling controller coupled with a processor and a memory. The UE attaching procedure handling controller is configured to receive a request message from a UE. Further, the UE attaching procedure handling controller is configured to identify that the UE has not been authenticated as at least one UE detail is not available onboard a satellite. Further, the UE attaching procedure handling controller is configured to store the request message. Further, the UE attaching procedure handling controller is configured to trigger to perform S&F operation. Further, the UE attaching procedure handling controller is configured to complete a NAS procedure in a single operation.

[0044] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating at least one embodiment and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

[0045] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0046] For the purposes of interpreting this specification, the definitions (as defined herein) will apply and whenever appropriate the terms used in singular will also include the plural and vice versa. It is to be understood that the terminology used herein is for the purposes of describing particular embodiments only and is not intended to be limiting. The terms "comprising", "having" and "including" are to be construed as open-ended terms unless otherwise noted.

[0047] The words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.," , "i.e.," are merely used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein using the words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.," , "i.e.," is not necessarily to be construed as preferred or advantageous over other embodiments.

[0048] Embodiments herein may be described and illustrated in terms of blocks which carry out a described function or functions.　These blocks, which may be referred to herein as managers, units, modules, hardware components or the like, are physically implemented by analog and / or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits and the like, and may optionally be driven by a firmware. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like.　The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block.　Each block of the embodiments may be physically separated into two or more interacting and discrete blocks without departing from the scope of the disclosure.　Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the disclosure.

[0049] It should be noted that elements in the drawings are illustrated for the purposes of this description and ease of understanding and may not have necessarily been drawn to scale. For example, the flowcharts / sequence diagrams illustrate the method in terms of the steps required for understanding aspects of the embodiments as disclosed herein. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Furthermore, in terms of the system, one or more components / modules which comprise the system may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0050] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any modifications, equivalents, and substitutes in addition to those which are particularly set out in the accompanying drawings and the corresponding description. Usage of words such as first, second, third etc., to describe components / elements / steps is for the purposes of this description and should not be construed as sequential ordering / placement / occurrence unless specified otherwise.

[0051] The embodiments herein disclose a method to perform an attach procedure in a satellite communication. The method includes receiving, by a MME, a request message from a User Equipment (UE). Further, the method includes identifying, by the MME, that the UE has not been authenticated upon receiving the requested message as at least one UE detail is not available onboard a satellite. Further, the method includes storing, by the MME, the request message. Further, the method includes triggering, by the MME, to perform Store and Forward (S&F) operation. Further, the method includes completing, by the MME, a Non-access stratum (NAS) procedure in a single operation.

[0052] Referring now to the drawings, and more particularly to FIGS. 4 through 8, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0053] The present disclosure provides techniques to expedite the process of a user equipment's attachment to the network, when the network includes non-terrestrial radio access network. The method discloses prefetching subscription data for the UE registration process to reduce the registration time. The methods further disclosed herein provide techniques to modify the standard attach procedure to cater to the discontinuous nature of coverage provided by satellites and completed in fewer revolutions of the satellite around earth. Hence, the present disclosure provides a method and system to adjust user-to-network communication procedures in 4G and 5G systems to cater to the discontinuous nature of coverage provided by satellites.

[0054] The following abbreviations and definitions have been referred to herein:

[0055] MME: Mobility Management Entity

[0056] AMF: Access and Mobility Function

[0057] AUSF: Authentication Server Function

[0058] UDM: Unified Data Management

[0059] UE: User Equipment

[0060] HSS: Home Subscriber Service

[0061] 3gpp: 3rd Generation Partnership Project

[0062] SUCI: Subscriber Concealed Identifier

[0063] PLMN: Public Land Mobile Network

[0064] EPS: Evolved Packet System

[0065] 5GS: 5G System

[0066] GUTI: Globally Unique Temporary Identity

[0067] gNB: Next generation Node-B

[0068] SAT: Satellite

[0069] SIM: Subscriber Identity Module.

[0070] Satellite: An artificial body placed in orbit round the earth or moon or another planet in order to collect information or for communication.

[0071] Satellite Constellation: Group of satellites, placed in orbit round the earth or moon or another planet in order to collect information or for communication.

[0072] Service User: An individual who has received a priority level assignment from a regional / national authority (i.e., an agency authorized to issue priority assignments) and has a subscription to a mobile network operator

[0073] The 3GPP is studying control and user plane enhancements required to support a Store-and-Forward operation for delay-tolerant services, for Internet of thing (IoT) devices connected via satellite, when the satellite provides a discontinuous coverage and is not connected to a User Equipment (UE) and a packet core network (partial or full) simultaneously. The study encompasses both Evolved Packet System　(EPS) and fifth generation system (5GS).

[0074] FIG. 1 is an example representation of simultaneous unavailability of Service and Feeder Links resulting in the problems described herein. FIG. 1 shows an IoT device on a remote location 'A' (e.g. a ship) (106), which is connected to a satellite (104) via a service link. When the satellite (104) is serving the location 'A' (106), it has no connectivity to a ground station and hence any signalling or data message(s) received from the IoT device cannot be delivered to the application functions and / or 3gpp network functions connected via the ground station. The satellite (104) will have to "store" one or more message(s) for some time. Later, when the satellite (104) moves and covers a location 'B' (108), and has connectivity with the ground station (110) via a feeder link, it can then "forward" the one or more messages from the location (104) it stored earlier. However, for the messages received from network (e.g. 3GPP NFs) (112) to be sent to UE (1000), the satellite (104) will again have to store those and forward when it regains connectivity with the mobile (1000). Such lack of simultaneous availability of the service link and the feeder link to the UE gives rise to use of store-and-forward delivery mechanism for delay-tolerant services.

[0075] As defined in 3GPP technical specification (TS) 23.502 Clause 4.2.2 for 5GS, and in 3GPP TS 23.401 Clause 5.3.2 for EPS, before the UE can avail services provided by the network, it needs to register with the network. The procedure of registration involves back-and-forth exchange of the message between the UE and the network, which starts with the sending of a Registration Request (5GS), or an Attach Request (EPS) by the UE (1000), followed by authentication of the UE (1000), and then subscription validation by the network.

[0076] However, with the discontinuous coverage and unavailability of simultaneous service and feeder links (as described in FIG. 1), such back-and-forth exchange of messages is not possible. Hence, before the UE can start using store-and-forward mechanism to send a data (for example, sensor data) to the network, the UE needs to wait a long time to even register to the network. If the satellite (104) is available in location 'A' (106) every two hours, the registration procedure itself may require 6-8 hours (for example) to complete. A similar issue will be seen upon every signalling message that the UE (1000) needs to send.

[0077] Hence, there is a need to reduce the time it takes to register to the network so that the UE can start consuming services sooner.

[0078] Consider that at-least the radio resource management is performed on the satellite, and hence any or all RAN nodes (such as, but not limited to, gNB, eNB, ng-eNB, and so on) are on-board the satellite. Some of the packet core nodes (such as, but not limited to, Access and Mobility Management Function　(AMF), Session Management Function　(SMF), user plane function (UPF), Authentication Server Function　(AUSF), Unified data management　(UDM), Mobility Management　Entity　(MME), Serving Gateway (SGW), primary Gateway (PGW), or partial functionality of these nodes) may also be present on-board the satellite, otherwise those will be present on-ground.

[0079] FIG. 2 depicts a representation of delayed attach procedure due to satellite movement & simultaneous unavailability of Service and Feeder Links in the EPS system. The procedure depicted in FIG. 2 is a simplified version of the Attach procedure defined in 3GPP TS 23.401 Clause 5.3.2.1 and some messages are not necessary to illustrate the problem / solution in the patent disclosure have been omitted. Similarly, the authentication procedure is a simplified version of the full procedure as defined in 3GPP TS 33.401 Clause 6.1. Additionally, for the purpose of illustration, it is assumed that the MME, or partial functionality of the MME is implemented on-board the satellite along with eNB. The Home Subscriber Service (HSS) (1300) is on-ground in this illustration.

[0080] In step 1, UE (1000) sends an Attach Request to the eNB on-board the satellite, which forwards the attach request to the MME on-board. The attach request contains UE-Identity (old- Globally Unique Temporary Identity (GUTI) or International Mobile Subscriber Identity (IMSI)) together with other parameters defined in 3GPP TS 23.401 Clause 5.3.2.1. If the MME on-board does not identify the old-GUTI due for any reason, the MME on-board may retrieve UE Identity (e.g. IMSI) from the UE before proceeding to the next step. Since the MME on-board is not connected to the HSS on-ground due to feeder-link unavailability at this point of time, the MME on-board awaits for availability of feeder-link before executing next step.

[0081] In step 2, when the MME regains feeder-link connectivity, the MME sends Authentication Data / Information Request to the HSS (1300) to retrieve Authentication Vectors as defined in Clause 6.1.2 of 3GPP TS 33.401. In step 3, the HSS entity (1300) responds with requested information in Authentication Data / Information Response. Since the MME on-board is not connected to the UE on-ground due to service-link unavailability at this point of time, it awaits for availability of service-link before executing next step.

[0082] In step 4, when the MME regains service-link connectivity, the MME sends User Authentication Request to the UE (1000) with an authentication challenge as defined in Clause 6.1.1 of 3GPP TS 33.401. In step 5, the UE (1000) generates user authentication response and provides the same to the MME in a User Authentication Response message. In step 6, the MME validates the authentication response and determines if the authentication is successful. If the authentication is successful, the MME proceeds with the next steps. If the authentication is not successful the MME may send an authentication reject message to the UE (1000) and terminates the Attach procedure. Since the MME on-board is not connected to the HSS on-ground (1300) due to feeder-link unavailability at this point of time, the MME on-board awaits for availability of feeder-link before executing next step.

[0083] In step 7, when the MME regains feeder-link connectivity, the MME sends an Update Location Request to the HSS (1300) to indicate it has an authenticated UE and request subscription data of the UE. In step 8, the HSS (1300) responds with Update Location Acknowledgement / Answer including UE subscription data. This is followed by validation of UE attach request in the serving network against subscription data. Since the MME on-board is not connected to the UE on-ground due to service-link unavailability at this point of time, the MME on-board awaits for the availability of service-link before executing the next step. In step 9, when the MME regains service-link connectivity, the MME on-board sends the Attach Accept to the UE (1000) containing GUTI. In Step 10, the UE (1000) responds with Attach Complete message.

[0084] FIG. 3 depicts a representation of delayed registration procedure due to satellite movement & simultaneous unavailability of Service and Feeder Links in 5G system. Consider the case of 5GS as described in FIG. 3. The procedure depicted in FIG. 3 is a simplified version of the Registration procedure defined in 3GPP TS 23.502 Clause 4.2.2.2 and some messages not necessary to illustrate the problem / solution in the patent document have been omitted. Similarly, the authentication procedure is a simplified version of the full procedure as defined in 3GPP TS 33.501 Clause 6.1. Additionally, for the purpose of illustration, it is assumed that the AMF (1100), or partial functionality of the AMF (1100) is implemented on-board the satellite along with an gNB Unified Data Repository　(UDR) and the AUSF (1200) are on-ground in this illustration.

[0085] In step 1, the UE (1000) sends a Registration Request to the gNB on-board the satellite, which forwards the Registration Request to the AMF on-board (1100). The request contains UE-Identity (old 5G-GUTI or SUCI) together with other parameters as defined in 3GPP TS 23.502 Clause 4.2.2.2. If the AMF on-board (1100) does not identify the 5G-GUTI due to any reason, the AMF on-board (1100) may retrieve the UE Identity (e.g. SUCI) from the UE (1100) before proceeding to next step. Since the AMF on-board is not connected to the AUSF (1200) / UDM on-ground due to feeder-link unavailability at this point of time, it waits for availability of feeder-link before executing step 2.

[0086] In step 2, when the AMF (1100) regains feeder-link connectivity, the AMF (1100) sends the Nausf_UEAuthentication_Authenticate Request message to the AUSF (1200) to start authentication procedure as defined in Clause 6.1.2 of 3GPP TS 33.501. In step 3, the AUSF (1200) validates if the AMF (1100) is allowed to use the serving network name included in incoming request and sends a Nudm_UEAuthentication_Get Request to the UDM (1400) to retrieve authentication vectors. In step 4, the UDM (1400) responds with requested information by sending Nudm_UEAuthentication_Get Response. In step 5, the AUSF (1200) sends a Nausf_UEAuthentication_Authenticate Response message to the AMF (1100) with authentication data as defined in Clause 6.1.3 of 3GPP TS 33.501. Since the AMF on-board is not connected to the UE on-ground due to service-link unavailability at this point of time, it waits for availability of service-link before executing the next step.

[0087] In step 6, when the AMF regains service-link connectivity, the AMF sends User Authentication Request to the UE. In step 7, the UE (1000) generates an authentication response and provides the same to the AMF (1100) in a User Authentication Response message. Since the AMF on-board is not connected to the AUSF on-ground due to feeder-link unavailability at this point of time, it waits for availability of feeder-link before executing next step. In step 8, when the AMF (1100) regains feeder-link connectivity, AMF (1100) sends Nausf_UEAuthentication_Authenticate Request message to the AUSF containing authentication response generated by the UE. In step 9, the AUSF (1200) validates the authentication response and determines if the authentication is successful.

[0088] In step 10, the AUSF (1200) sends a Nausf_UEAuthentication_Authenticate Response message to the AMF (1100) indicating result of authentication. If the authentication is successful, the AMF (1100) proceeds with the next steps. If the authentication is not successful it may send an authentication reject message to the UE upon next availability of Service Link, and terminate Registration procedure.

[0089] In step 11, the AMF (1100) now sends a Nudm_UECM_Registration request to the UDM (1400) to indicate that it has an authenticated UE and registers itself in the UDM (1400). The UDM (1400) acknowledges the requests. In step 12, the AMF (1100) now requests a subscription data from the UDM (1400) by sending Nudm_SDM_Get request and UDM (1400) responds with subscription data. This is followed by validation of UE Registration request in the serving network against subscription data by the AMF (1100). Since the AMF on-board is not connected to the UE on-ground due to the service-link unavailability at this point of time, it waits for availability of service-link before executing next step. In step 13, when the AMF (1100) regains service-link connectivity, AMF (1100)sends the registration accept to the UE containing 5G-GUTI. In step 14, the UE (1000) responds with a Registration Complete message.

[0090] However, the procedures described above show that Registration procedure takes too long to complete as eNB / MME on-board or gNB / AMF on-board need to wait for either feeder-link or service-link availability before executing the next steps. In order to shorten the time, it takes the UE (1000) to register. For e.g. consider, the service link is available (i.e. satellite is in the UE's availability area) at 1O clock at which the UE sends Attach request message to the MME-onboard satellite. Now, the feeder link is established (i.e. an area where the satellite is able to connect to the ground station / ground network) after 8 hours' time at 9 O clock, as per traditional mechanism the MME should just fetch the authentication data and trigger authentication procedure with the UE - but the UE is not available now as there is no service link yet. The Service link is established after another 8 hours (at 17:00 hours) when satellite reaches the location where the UE is available, the MME performs authentication procedure with the UE - but the MME cannot perform rest of the steps of attach procedure because it does not have the subscription data of the UE. Thus the MME has to wait another 8 hours for the feeder link to be available i.e. at next day 1 O clock, the MME will fetch the subscription data from the HSS, but now the UE is again not available. The MME waits for the service link to be available and after another 8 hours i.e. at 9 O clock the MME executes the rest of the steps of attach procedure to complete the attach / registration procedure. i.e. it took 32 hours to complete attach procedure after the UE sends the attach / registration request to core network. This is a long time and not desirable.

[0091] Hence, there is a need in the art for solutions which will overcome the above-mentioned drawback(s), among others.

[0092] In an embodiment, FIG. 4 depicts a sequence representation of an example of improved attach procedure in EPS system, describing the benefits of the proposed solutions in detail for EPS especially against the problem defined in FIG. 2. In Step 1, the UE (1000) sends the Attach Request to the eNB on-board the satellite, which forwards it to the MME on-board. The attach request contains UE-Identity (old-GUTI or IMSI) together with other parameters defined in 3GPP TS 23.401 Clause 5.3.2.1. If the MME on-board (900) does not identify the old-GUTI due to any reason, the MME on-board (900) may retrieve a UE Identity (e.g., IMSI) from the UE (1000) before proceeding to next step. Since the MME on-board (900) is not connected to the HSS on-ground (1300) due to feeder-link unavailability at this point of time, it awaits for availability of feeder-link before executing next step.

[0093] In Step 2, when the MME (900) regains feeder-link connectivity, the MME (900) sends the authentication & subscription data request to the HSS (1300) to retrieve the authentication vectors and subscription data according to embodiments enclosed herein. As mentioned above, this could be implemented by modifying, e.g., the Authentication Information Request as defined in Clause 5.2.3.1.1 of 3GPP TS 29.272 as below:

[0094]

[0095]

[0096] In Step 3, the HSS (1300) responds with requested information in Authentication & Subscription Data Response. This could be implemented by modifying, e.g., the Authentication Information Response as defined in Clause 5.2.3.1.1 of 3GPP TS 29.272 as below:

[0097]

[0098]

[0099] Some of the subscription data provided by the HSS (1300) to the MME (900) may be filtered based on the information presented in Update Location Request by the MME (900). Such information may not be available to the MME (900) before completion of authentication. The delivery of such subscription information can be delayed to the Step 10, as applicable. Since the MME on-board (900) is not connected to the UE on-ground due to service-link unavailability at this point of time, it awaits for availability of service-link before executing next step. In Step 4, when the MME (900) regains service-link connectivity, the MME (900) sends the user authentication request to the UE (1000) with an authentication challenge as defined in Clause 6.1.1 of 3GPP TS 33.401. In Step 5, the UE (1000) generates authentication response and provides the same to MME (900) in a User Authentication Response message.

[0100] In Step 6 the MME (900) validates the authentication response and determines if the authentication is successful. If the authentication is successful, the MME (900) proceeds with next steps. If the authentication is not successful, the MME (900) may send an authentication reject message to the UE (1000) and terminate Attach procedure. In Step 7, Since the MME (900) already has subscription data available, validation of UE attach request against subscription data follows. In Step 8, the MME (900) sends the Attach Accept to the UE containing GUTI. In Step 9, the UE (1000) responds with Attach Complete message. In Step 10, and 11, This is followed by the Updated Location Request / Response upon next Feeder Link availability, to update the HSS and the MME has authenticated UE in the given serving-network, and retrieve remaining subscription data, if applicable. Thus, the attach procedure can be completed in single round of the satellite rotation around the earth. The various actions in method may be performed in the order presented, in a different order or simultaneously.

[0101] FIG. 5 depicts a representation of a method (500) for attaching the UE (1000) to the Non-Terrestrial Network with respect to an on-board entity by the MME (900), according to the embodiments as disclosed herein.

[0102] At 502, the method includes receiving the request message from the UE (1000). At 504, the method includes identifying that the UE (1000) has not been authenticated upon receiving the requested message as at least one UE detail is not available onboard a satellite. At 506, the method includes storing the request message. At 508, the method includes triggering to perform a S&F operation. At 510, the method includes completing the NAS procedure in a single operation.

[0103] FIG. 6 depicts a sequence representation of an example of improved registration procedure in 5G system, according to embodiments as disclosed herein. Moreover, FIG. 6 describing the benefits of the proposed solutions in detail for 5GS especially against the problem defined in FIG. 3. The UE begins registration by sending its identity (e.g., 5G-GUTI or SUCI) to the gNB on a satellite, which forwards it to the AMF on-board. If 5G-GUTI is not recognized, the AMF retrieves SUCI directly from the UE. Due to temporary feeder-link unavailability, the AMF on-board waits for connectivity to resume before sending the request to the ground AMF. Once connected, the ground AMF authenticates the UE through the AUSF and registers it with the UDM, retrieving necessary data. The AMF on-board completes registration with the UE when service-link is available, finalizing with Registration Complete.

[0104] In step 1, the UE sends a Registration Request to the gNB on-board the satellite, which forwards it to the AMF on-board. The request contains UE-Identity (old 5G-GUTI or SUCI) together with other parameters as defined in 3GPP TS 23.502 Clause 4.2.2.2. If the AMF on-board does not identify the 5G-GUTI due to any reason, it may retrieve the UE Identity (e.g., SUCI) from the UE before proceeding to next step. Since the AMF on-board is not connected to the AUSF / UDM on-ground due to feeder-link unavailability at this point of time, it waits for availability of feeder-link before executing step 2.

[0105] In step 2, when the satellite regains feeder-link connectivity, the AMF on-board sends a Registration Request to the AMF on-ground. The communication between the AMF on-board satellite and the AMF on-ground may use implementation specific protocol and may include additional information, for example, last-known location of the UE. In step 3, the AMF on-ground sends the Nausf_UEAuthentication_Authenticate Request message to the AUSF to start authentication procedure as defined in Clause 6.1.2 of 3GPP TS 33.501. The request may include an indication that the UE is working in store-and-forward mode. In step 4, the AUSF validates if the AMF on-ground is allowed to use the serving network name included in the incoming request and retrieves the UE authentication information using Nudm_UEAuthentication_Get service operation. The request may include an indication that the UE is working in store-and-forward mode. The UDM may use this indication to prefer, for example, 5G to authenticate the UE.

[0106] In step 5, the AUSF sends a Nausf_UEAuthentication_Authenticate Response message (for example, Nausf_UEAuthentication_Authenticate_Response) to the AMF on-ground with authentication data as defined in Clause 6.1.3 of 3GPP TS 33.501. The response may include authentication vectors and the KSEAF. In step 6, the AMF on-ground sends a Nudm_UECM_Registration request to the UDM to indicate that the AMF on-ground wants to register in the UDM for a given UE. The request may include an indication that the UE is working in store-and-forward mode. Alternatively, the UDM may use the indication provided by the AUSF in Step 4 and / or UE's subscription data and / or local configuration to check if the Nudm_UECM_Registration request can be accepted before completion of authentication procedure. The UDM subsequently acknowledges the requests.

[0107] In step 7, if the Nudm_UECM request was accepted, the AMF on-ground now requests subscription data from the UDM by sending Nudm_SDM_Get request and the UDM responds with subscription data (for example, Nudm_SDM_Get). This is followed by validation of UE Registration request in the serving network against subscription data by the AMF. In step 8, the AMF on-ground uploads the UE's authentication data and subscription data into the AMF on-board. Since the AMF on-board is not connected to the UE on-ground due to service-link unavailability at this point of time, it waits for availability of service-link before executing next step.

[0108] In step 9, when the AMF regains service-link connectivity, it performs UE authentication procedure and validates, for example, UE in the serving-network. This is followed by Security Mode Command / Complete procedure. In step 10, the AMF on-board sends a Registration Accept message to the UE. In step 11, the UE sends a Registration Complete. Since the AMF on-board is not connected to the AUSF / UDM on-ground due to feeder-link unavailability at this point of time, it waits for availability of feeder-link before executing next step. In step 12, regaining feeder link connectivity, the AMF on-board sends Authentication Result (e.g., RES*) and UE-Context to the AMF on-ground. In step 13, the AMF on-ground sends authentication result to the AUSF using a Nausf_UEAuthentication_Authenticate procedure. In step 14, the AMF on-ground informs the UDM about successful completion of the UE's registration using Nudm_UECM_Registration procedure (for example, Nudm_UECM_Registration). Thus, the attach procedure can be completed in single round of the satellite rotation around the earth.

[0109] In an embodiment herein, the Nausf_UEAuthentication_Authenticate Request message can be sent to an Authentication Server Function (AUSF) to authenticate by an Evolved Packet System (EPS) or a Next Generation Node B (gNB) 5G system, wherein the request includes an indication that the UE is working in store-and-forward mode.

[0110] In an embodiment herein, the method discloses sending a Nudm_UECM_Registration request, by the Evolved Packet System (EPS) or a Next Generation Node B (gNB) 5G system, to the UDM to indicate the Mobility Management Entity (MME) or Access and Mobility Management Function (AMF) on-ground wants to register itself in the UDM for a given UE, wherein the UE is working in store-and-forward mode, if the Nudm_UECM request is accepted, the AMF on-ground now requests subscription data from the UDM by sending Nudm_SDM_Get request and the UDM responds with subscription data, validate the UE Registration request in the serving network against subscription data, upload the UE's authentication data and subscription data into the AMF on-board, wherein the AMF on-board is not connected to the UE on-ground due to service-link unavailability at this point of time, it waits for availability of service-link before executing next step, and regain the feeder-link connectivity by the Mobility Management Entity (MME) or Access and Mobility Management Function (AMF) on-ground, wherein the AMF on-board sends Authentication Result and UE to the AMF on-ground.

[0111] In an embodiment herein, the method validates Evolved Packet System (EPS) or a Next Generation Node B (gNB) 5G system on-ground by the AUSF and can be allowed to use the serving network name included in the incoming request and retrieves the UE authentication information using Nudm_UEAuthentication_Get service operation.

[0112] FIG. 7 is a schematic example scenario (700) to perform an attach procedure of UE in a satellite communication to the network to shorten the registration time, according to embodiments as disclosed herein. As the illustration depicts, the UE is on a remote location and is connected to the satellite via the service link. When the satellite is serving at time T1 at a location (for example location: A) (800a) (1 it has no connection to ground station and hence any signal / data received from UE cannot be delivered to the application functions and / or 3gpp network functions connected via the ground station. The UE initiates registration request / attach request to the satellite and identifies that the UE has not been authenticated upon receiving the requested message as the UE details is not available on the satellite. The satellite will "store" the message(s) for some time. Later, when the satellite approaches a new location (for example, location B) (800b) at time say T2 and has connectivity with the ground station via a feeder link, it can then "forward" the messages from the mobile it stored earlier. The UE (1000) stores and forwards the signal / data received by the MME by detecting when a feeder link is available, fetching at least one UE authentication detail from an HSS, prefetching at least one UE subscription details from HSS, storing the at least one UE authentication detail and the at least one pre fetched UE subscription detail. For example consider the service link is available (i.e. satellite is in the UE's availability area) at 1 O clock at which the UE sends the Attach request message to the MME-onboard satellite. Now, the feeder link is established (i.e. an area where the satellite is able to connect to ground station / ground network) after 8 hours' time at 9 O clock, as per traditional mechanism the MME should fetch the authentication data and trigger authentication procedure with the UE - but the UE is not available now as there is no service link yet. The MME also pre-fetches the subscription data of the UE by triggering example update location procedure. The Service link is established after another 8 hours (at 17:00 hours) when satellite reaches the location where the UE is available, the MME performs authentication procedure with the UE and also perform rest of the steps of attach procedure because it has pre-fetched the subscription data of the UE too. i.e. it took only 16 hours to complete the attach procedure after the UE sends the attach / registration request to the core network. This will considerably reduce the time required to perform attach / registration procedure with the network. Given subscription data was fetched before authenticating the UE, the success / failure status of the UE authentication / registration / attach procedure is indicated back to the HSS.

[0113] FIG. 8 depicts various hardware components of the MME (900), according to the embodiments as disclosed herein. The MME is at least one of: an onboard MME and a ground MME. The MME (900) comprises a transceiver (810), a processor (830), and a memory (820). The MME(900) further includes a UE attaching procedure handling controller.

[0114] The transceiver (810) collectively refers to a network entity receiver and a network entity transmitter, and may transmit / receive a signal to / from a base station or a UE. The signal transmitted or received to or from the base station or the UE may include control information and data. In this regard, the transceiver (810) may include an RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and an RF receiver for amplifying low-noise and down-converting a frequency of a received signal. However, this is only an example of the transceiver (810) and components of the transceiver (810) are not limited to the RF transmitter and the RF receiver.

[0115] The transceiver (810) may receive and output, to the processor (830), a signal through a wireless channel, and transmit a signal output from the processor (830) through the wireless channel.

[0116] The UE attaching procedure handling controller receives the request message from the UE (1000). Further, the UE attaching procedure handling controller identifies that the UE (1000) has not been authenticated as at least one UE detail is not available onboard a satellite. Further, the UE attaching procedure handling controller stores the request message.

[0117] Further, the UE attaching procedure handling controller triggers to perform S&F operation. In an embodiment, the UE attaching procedure handling controller detects when the feeder link is available. Further, the UE attaching procedure handling controller fetches the UE authentication detail from the HSS. In an embodiment, the at least one UE authentication detail is at least one of: at least one of authentication vector and a key use to execute an authentication procedure. Further, the UE attaching procedure handling controller pre fetches the UE subscription detail from HSS i.e. even before the authentication procedure is executed with the UEto achieve this the MME triggers the Update Location procedure with the HSS along with the authentication procedure to fetch subscription information from the HSS, In an embodiment, the MME may execute the authentication procedure with the HSS first or the update location procedure with the HSS first. In an embodiment, the at least one UE subscription detail is a UE subscription information stored at an HSS. Further, the UE attaching procedure handling controller stores the UE authentication detail and the pre fetched UE subscription detail. The MME pre-fetches the UE subscription detail from the HSS before executing an authentication procedure with the UE.

[0118] Further, the UE attaching procedure handling controller completes a NAS procedure in a single operation. In an embodiment, the UE attaching procedure handling controller detects when the service link is available. Further, the UE attaching procedure handling controller performs the authentication procedure with the UE. Further, the UE attaching procedure handling controller executes remaining steps of the attach procedure with the at least one pre fetched UE subscription detail from the HSS. Further, the UE attaching procedure handling controller detects when a feeder link is available. Further, the UE attaching procedure handling controller indicates to the HSS whether the authentication procedure is successful.

[0119] In an embodiment, when the at least one UE detail is not available onboard the satellite, the MME does not complete the NAS procedure with an information currently available on the satellite due to: the MME does not have at least one of: a UE security context, a UE specific authentication vector, and a subscription information.

[0120] The UE attaching procedure handling controller is implemented by analog and / or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits and the like, and may optionally be driven by firmware.

[0121] The processor (830) may include one or a plurality of processors. The one or the plurality of processors may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an AI-dedicated processor such as a neural processing unit (NPU). The processor (830) may include multiple cores and is configured to execute the instructions stored in the memory (820).

[0122] Further, the processor (830) is configured to execute instructions stored in the memory (820) and to perform various processes. A communicator (not shown) is configured for communicating internally between internal hardware components and with external devices via one or more networks. The memory (820) also stores instructions to be executed by the processor (830). The memory (820) may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories. In addition, the memory (820) may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term "non-transitory" should not be interpreted that the memory (820) is non-movable. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

[0123] FIG. 9 illustrates a structure of a base station according to an embodiment of the disclosure.

[0124] As shown in FIG. 9, the base station according to an embodiment may include a transceiver (910), a memory (920), and a processor (930). The transceiver (910), the memory (920), and the processor (930) of the base station may operate according to a communication method of the base station described above. However, the components of the base station are not limited thereto. For example, the base station may include more or fewer components than those described above. In addition, the processor (930), the transceiver (910), and the memory (920) may be implemented as a single chip. Also, the processor (930) may include at least one processor. Furthermore, the base station of FIG. 9 corresponds to the gNB above.

[0125] The transceiver (910) collectively refers to a base station receiver and a base station transmitter, and may transmit / receive a signal to / from a terminal(UE) or a network entity. The signal transmitted or received to or from the terminal or a network entity may include control information and data. The transceiver (910) may include a RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and a RF receiver for amplifying low-noise and down-converting a frequency of a received signal. However, this is only an example of the transceiver (910) and components of the transceiver (910) are not limited to the RF transmitter and the RF receiver.

[0126] Also, the transceiver (910) may receive and output, to the processor (930), a signal through a wireless channel, and transmit a signal output from the processor (930) through the wireless channel.

[0127] The memory (920) may store a program and data required for operations of the base station. Also, the memory (920) may store control information or data included in a signal obtained by the base station. The memory (920) may be a storage medium, such as read-only memory (ROM), random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0128] The processor (930) may control a series of processes such that the base station operates as described above. For example, the transceiver (910) may receive a data signal including a control signal transmitted by the terminal, and the processor (930) may determine a result of receiving the control signal and the data signal transmitted by the terminal.

[0129] FIG. 10 illustrates a structure of a UE according to an embodiment of the disclosure.

[0130] As shown in FIG. 10, the UE according to an embodiment may include a transceiver (1010), a memory (1020), and a processor (1030). The transceiver (1010), the memory (1020), and the processor (1030) of the UE may operate according to a communication method of the UE described above. However, the components of the UE are not limited thereto. For example, the UE may include more or fewer components than those described above. In addition, the processor (1030), the transceiver (1010), and the memory (1020) may be implemented as a single chip. Also, the processor (1030) may include at least one processor. Furthermore, the UE of FIG. 10 corresponds to the UE (1000).

[0131] The transceiver (1010) collectively refers to a UE receiver and a UE transmitter, and may transmit / receive a signal to / from a base station or a network entity. The signal transmitted or received to or from the base station or a network entity may include control information and data. The transceiver (1010) may include a RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and a RF receiver for amplifying low-noise and down-converting a frequency of a received signal. However, this is only an example of the transceiver (1010) and components of the transceiver (1010) are not limited to the RF transmitter and the RF receiver.

[0132] Also, the transceiver (1010) may receive and output, to the processor (1030), a signal through a wireless channel, and transmit a signal output from the processor (1030) through the wireless channel.

[0133] The memory (1020) may store a program and data required for operations of the UE. Also, the memory (1020) may store control information or data included in a signal obtained by the UE. The memory (1020) may be a storage medium, such as read-only memory (ROM), random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0134] The processor (1030) may control a series of processes such that the UE operates as described above. For example, the transceiver (1010) may receive a data signal including a control signal transmitted by the base station or the network entity, and the processor (1030) may determine a result of receiving the control signal and the data signal transmitted by the base station or the network entity.

[0135] Those skilled in the art will understand that the various illustrative logical blocks, modules, circuits, and steps described in this application may be implemented as hardware, software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in the form of their functional sets. Whether such function sets are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Technicians may implement the described functional sets in different ways for each specific application, but such design decisions should not be interpreted as causing a departure from the scope of this application.

[0136] In the above-described embodiments of the disclosure, all operations and messages may be selectively performed or may be omitted. In addition, the operations in each embodiment do not need to be performed sequentially, and the order of operations may vary. Messages do not need to be transmitted in order, and the transmission order of messages may change. Each operation and transfer of each message can be performed independently.

[0137] Although the figures illustrate different examples of user equipment, various changes may be made to the figures. For example, the user equipment can include any number of each component in any suitable arrangement. In general, the figures do not limit the scope of this disclosure to any particular configuration(s). Moreover, while figures illustrate operational environments in which various user equipment features disclosed in this patent document can be used, these features can be used in any other suitable system.

[0138] The various illustrative logic blocks, modules, and circuits described in this application may be implemented or performed by a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic devices, discrete gates or transistor logics, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0139] The steps of the method or algorithm described in this application may be embodied directly in hardware, in a software module executed by a processor, or in a combination thereof. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, register, hard disk, removable disk, or any other form of storage medium known in the art. A storage medium is coupled to a processor to enable the processor to read and write information from / to the storage media. In an alternative, the storage medium may be integrated into the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in the user terminal as discrete components.

[0140] In one or more designs, the functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, each function may be stored as one or more pieces of instructions or codes on a computer-readable medium or delivered through it. The computer-readable medium includes both a computer storage medium and a communication medium, the latter including any medium that facilitates the transfer of computer programs from one place to another. The storage medium may be any available medium that can be accessed by a general purpose or special purpose computer.

[0141] While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.

Claims

1.A method performed by a mobility management entity (MME) in a wireless communication system, the method comprising:receiving, from a home subscriber server (HSS) entity, an authentication vector and data for a user equipment (UE); andretrieving subscription data among the data for the UE based on an acknowledgment (ACK) for an update location request.2.The method of claim 1, further comprising,transmitting, to the HSS entity, the update location request,wherein the update location request indicates a pre-fetching to receive the subscription data without an authentication for the UE.3.The method of claim 1,wherein, in case that the update location request includes a result of an authentication for the UE, the update location request indicates that the subscription data is not required.4.The method of claim 1,wherein the MME includes a first MME which is onboard a satellite and a second MME which is on a ground network.5.A method performed by a home subscriber server (HSS) entity in a wireless communication system, the method comprising:transmitting, to a mobility management entity (MME), an authentication vector and data for a user equipment (UE),wherein subscription data among the data for the UE is based on an acknowledgment (ACK) for an update location request.6.The method of claim 5, further comprising,receiving, from the MME, the update location request; andidentifying a pre-fetching to transmit the subscription data without an authentication for the UE, based on the update location request.7.The method of claim 5,wherein, in case that the update location request includes a result of an authentication for the UE, the update location request indicates that the subscription data is not required.8.The method of claim 5,wherein the MME includes a first MME which is onboard a satellite and a second MME which is on a ground network.9.A mobility management entity (MME) in a wireless communication system, the MME comprising:a transceiver; andat least one processor coupled with the transceiver and configured to:receive, from a home subscriber server (HSS) entity, an authentication vector and data for a user equipment (UE), andretrieve subscription data among the data for the UE based on an acknowledgment (ACK) for an update location request.10.The MME of claim 9, at least one processor is further configured to:transmit, to the HSS entity, the update location request,wherein the update location request indicates a pre-fetching to receive the subscription data without an authentication for the UE.11.The MME of claim 9,wherein, in case that the update location request includes a result of an authentication for the UE, the update location request indicates that the subscription data is not required.12.The MME of claim 9,wherein the MME includes a first MME which is onboard a satellite and a second MME which is on a ground network.13.A home subscriber server (HSS) entity in a wireless communication system, the HSS entity comprising:a transceiver; andat least one processor coupled with the transceiver and configured to:transmit, to a mobility management entity (MME), an authentication vector and data for a user equipment (UE),wherein subscription data among the data for the UE is based on an acknowledgment (ACK) for an update location request.14.The HSS entity of claim 13, at least one processor is further configured to:receive, from the MME, the update location request, andidentify a pre-fetching to transmit the subscription data without an authentication for the UE, based on the update location request.15.The HSS entity of claim 13,wherein, in case that the update location request includes a result of an authentication for the UE, the update location request indicates that the subscription data is not required.

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