Methods and systems for handling periodic registration for store and forward services

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. In an embodiment of the disclosure, a method performed by a first network entity on a ground network in a wireless communication system, may comprise receiving, from a second network entity onboard a satellite, information for a UE indicating that the UE gets in a connected mode with the second network entity and starting a MRT associated with the UE based on the information for the UE.

Description

METHODS AND SYSTEMS FOR HANDLING PERIODIC REGISTRATION FOR STORE AND FORWARD SERVICES

[0001] Embodiments disclosed herein relate to wireless communication networks, and more particularly to handling periodic registration for Store & Forward (S&F) operations in wireless communication networks.

[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 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] In an embodiment of the disclosure, a method performed by a first network entity on a ground network in a wireless communication system may comprise receiving, from a second network entity onboard a satellite, information for a User Equipment (UE) indicating that the UE gets in a connected mode with the second network entity. In an embodiment of the disclosure, the method performed by the first network entity may comprise starting a Mobile Reachable Timer (MRT) associated with the UE based on the information for the UE.

[0009] In an embodiment of the disclosure, a method performed by a second network entity onboard a satellite in a wireless communication system may comprise identifying that a UE gets in a connected mode with the second network entity. In an embodiment of the disclosure, the method performed by the second network entity may comprise transmitting, to a first network entity on the ground network, information for the UE indicating that the UE gets in the connected mode with the second network entity. In an embodiment of the disclosure, the information for the UE may be a basis for starting a MRT associated with the UE at the first network entity.

[0010] In an embodiment of the disclosure, a first network entity on a ground network in a wireless communication system may comprise a transceiver and at least one processor coupled to the transceiver. In an embodiment of the disclosure, the at least one processor may be configured to receive, from a second network entity onboard a satellite, information for a UE indicating that the UE gets in a connected mode with the second network entity. In an embodiment of the disclosure, the at least one processor may be configured to start a MRT associated with the UE based on the information for the UE.

[0011] In an embodiment of the disclosure, a second network entity onboard a satellite in a wireless communication system may comprise a transceiver and at least one processor coupled to the transceiver. In an embodiment of the disclosure, the at least one processor may be configured to identify that a UE gets in a connected mode with the second network entity. In an embodiment of the disclosure, the at least one processor may be configured to transmit, to a first network entity on the ground network, information for the UE indicating that the UE gets in the connected mode with the second network entity. In an embodiment of the disclosure, the information for the UE may be a basis for starting a MRT associated with the UE at the first network entity.

[0012] 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.

[0013] 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:

[0014] FIG 1A depicts the normal / default Satellite operation mode, according to an embodiment of the disclosure;

[0015] FIG 1B depicts the Store & Forward (S&F) Satellite operation mode, according to an embodiment of the disclosure;

[0016] FIG. 2 depicts a scenario, wherein the feeder link is not available in a satellite communication network, according to an embodiment of the disclosure;

[0017] FIG. 3 depicts the architecture of the satellite communication network, according to an embodiment of the disclosure;

[0018] FIG. 4A depicts the satellite network architecture at time T0, according to an embodiment of the disclosure;

[0019] FIG 4B depicts the satellite network architecture at time T1, according to an embodiment of the disclosure;

[0020] FIG 4C depicts the satellite network architecture at time T2, according to an embodiment of the disclosure;

[0021] FIG. 5 depicts an example scenario, wherein the Tracking Area Update flow is successful with MME / AMF on ground running MRT+IDT timers, according to an embodiment of the disclosure;

[0022] FIG. 6 depicts an example scenario, wherein the Tracking Area Update flow is successful with MME / AMF onboard all satellites running MRT+IDT timers, according to an embodiment of the disclosure;

[0023] FIG. 7 depicts the modified NAS and AS procedures between UE and CN entities / Network Functions, according to an embodiment of the disclosure;

[0024] FIG. 8 is a flowchart depicting a process for handling periodic registration for Store & Forward (S&F) services, according to an embodiment of the disclosure;

[0025] FIG. 9 illustrates a network entity according to an embodiment of the disclosure;

[0026] FIG. 10 illustrates an UE according to an embodiment of the disclosure;

[0027] FIG. 11 is a flowchart illustrating a method performed by a first network entity on a ground network in a wireless communication system according to an embodiment of the disclosure; and

[0028] FIG. 12 is a flowchart illustrating a method performed by a second network entity onboard a satellite in a wireless communication system according to an embodiment of the disclosure.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 of 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.

[0034] 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.

[0035] An object of an embodiment of the disclosure is to disclose methods and systems for handling EPS / 5GC Mobility Management timers (for example, UE or Network side) (in an example, MRT (Mobile Reachable Timer), PTAU (Periodic Tracking Area Update) timer or Timer 3412 or Periodic Registration Timer or T3512 and / or IDT (Implicit De-registration / Detach timer) be handled at MME / AMF onboard or MME / AMF on ground, when the architectural option with MME / AMF onboard (for example, MME lighter) is used along with MME / AMF on ground (full MME / AMF).

[0036] An object of an embodiment of the disclosure is to disclose methods and systems for syncing EPS / 5GC Mobility Management timers (for example, UE or Network side) (In an example, MRT, PTAU timer or Timer 3412 or Periodic Registration Timer or T3512 and / or IDT values between the ground MME / AMF and the MME / AMF onboard the satellites.

[0037] An object of an embodiment of the disclosure is to disclose modified Non-Access Stratum (NAS) and Access Stratum (AS) procedures between the UE and RAN / CN entities / Network Functions, considering the delay introduced between the UE + on-board network functions and network functions onground, wherein the procedures need to be separated considering that if they require to communicate with the ground station (network functions onground) or not.

[0038] An object of an embodiment of the disclosure is to disclose methods and systems for maintaining and syncing the UE context and / or parameters between the MME-onboard / AMF-onboard and the MME-onground / AMF-onground.

[0039] Accordingly, the embodiments herein provide a method for handling periodic registration for Store & Forward (S&F) services. The method comprises starting, by a Mobility Management Entity (MME), a Mobile Reachable Timer (MRT), and an Implicitly Detach Timer (IDT) for a User Equipment (UE) using a first value, wherein the first value of a periodic registration update timer is assigned to the UE, when the UE is registered in S&F mode. The method further comprises starting, by the MME, a MRT, and an IDT for the UE using a second value, wherein the second value of the periodic registration update timer is assigned to the UE, when the UE is not registered in S&F mode.

[0040] Accordingly, the embodiments herein provide a method for handling periodic registration for Store & Forward (S&F) services. The method comprises determining, by a Mobility Management Entity (MME)-onboard in a satellite, that a User Equipment (UE) has gotten in connected mode with the MME-onboard; and informing, by the MME-onboard, that the UE has gotten in connected mode with the MME-onboard to a MME-ground in a ground station.

[0041] Accordingly, the embodiments herein provide a Mobility Management Entity (MME), the MME comprising a processing module; a memory; and a transceiver. The processing module is coupled with the memory, and the transceiver, and configured to start a Mobile Reachable Timer (MRT), and an Implicitly Detach Timer (IDT) for a User Equipment (UE) using a first value, wherein the first value of a periodic registration update timer is assigned to the UE, when the UE is registered in S&F mode. The processing module is further configured to start an MRT, and an IDT for the UE using a second value, wherein the second value of the periodic registration update timer is assigned to the UE, when the UE is not registered in S&F mode.

[0042] Accordingly, the embodiments herein provide a Mobility Management Entity (MME) in a satellite, the MME comprising a processing module; a memory; and a transceiver. The processing module is coupled with the memory, and the transceiver, and configured to determine that a User Equipment (UE) has gotten in connected mode with the MME; and inform that the UE has gotten in connected mode with the MME to a MME-ground in a ground station.

[0043] For a Fifth Generation (5G) system with satellite access, the following requirements apply:

[0044] - The 5G system shall support service continuity between New Radio (NR) terrestrial access network and NR satellite access networks owned by the same operator or owned by 2 different operators having an agreement.

[0045] The Non-Terrestrial Network (NTN) and Terrestrial Network (TN) could either operate in two different frequency bands (e.g. FR1 vs FR2), or in the same frequency band (e.g. FR1 or FR2).

[0046] The Store and Forward (S&F) Satellite operation in a 5G system with satellite access is intended to provide some level of communication service for User Equipments (UEs) under satellite coverage with intermittent / temporary satellite connectivity (e.g., when the satellite is not connected via a feeder link or via Inter Satellite Link (ISL) to the ground network) for delay-tolerant communication service.

[0047] FIGs. 1A and 1B illustrate an example of "S&F Satellite operation" in contrast to what could be considered the current assumption for the "normal / default Satellite operation" of a 5G system with satellite access. FIG. 1A depicts the normal / default Satellite operation mode, according to an embodiment of the disclosure. FIG. 1B depicts the S&F Satellite operation mode, according to an embodiment of the disclosure. As shown in FIG. 1A, under "normal / default Satellite operation" mode, signalling and data traffic exchange between a UE with satellite access and the remote ground network requires the service and feeder links to be active simultaneously, so that, at the time that the UE interacts over the service link with the satellite, there is a continuous end-to-end connectivity path between the UE, the satellite and the ground network. In contrast, under "S&F Satellite operation" mode, the end-to-end exchange of signalling / data traffic is now handled as a combination of two steps not concurrent in time (steps A & B in FIG. 1B). In step A, signalling / data exchange between the UE and the satellite takes place, without the satellite being simultaneously connected to the ground network (i.e., the satellite can operate the service link without an active feeder link connection). In step B, connectivity between the satellite and the ground network is established so that communication between the satellite and the ground network can take place. So, the satellite moves from being connected to the UE in step A to being connected to the ground network in step B.

[0048] The concept of "S&F" service is widely used in the fields of delay-tolerant networking and disruption-tolerant networking. In an example 3GPP context, a service that could be assimilated to an S&F service is SMS, for which there is no need to have end-to-end connectivity between the endpoints (for example, an endpoint can be a UE and the other an application server), but only between the endpoints and the SMSC which acts as an intermediate node in charge of storing and relying. The support of S&F operation is especially suited for the delivery of delay-tolerant / non-real-time IoT satellite services with Non-Geostationary Orbit (NGSO) satellites.

[0049] The network supervises the periodic tracking area updating procedure of the UE by means of a mobile reachable timer (MRT). If the UE is not attached for emergency bearer services, the MRT shall be longer than T3412. In this case, by default, the MRT is 4 minutes greater than T3412. If Idle mode Signalling Reduction (ISR) is not activated, the network behaviour upon expiry of the MRT is network dependent, but typically the network stops sending paging messages to the UE on the first expiry, and may take other appropriate actions. If the UE is attached for emergency bearer services, the Mobility Management Entity (MME) shall set the mobile reachable timer with a value equal to T3412. When the MRT expires, the MME shall locally detach the UE. On the MME releasing the NAS signalling connection for the UE, the MRT shall be reset and started with its initial value. The MRT shall be stopped when a NAS signalling connection is established for the UE.

[0050] Upon expiry of the MRT, the network shall start the implicit detach timer (IDT). The value of the IDT is network dependent. If ISR is activated, the default value of the IDT is 4 minutes greater than T3423. If the IDT expires before the UE contacts the network, the network shall implicitly detach the UE. The IDT shall be stopped when a NAS signalling connection is established for the UE.

[0051] FIG. 2 depicts a scenario, wherein the feeder link is not available in a satellite communication network, according to an embodiment of the disclosure.

[0052] Table 1 depicts the 5GC mobility management timers - UE side.

[0053] TIMER NUM.TIMER VALUESTATECAUSE OF STARTNORMAL STOPONEXPIRYT3512Default 54 minNOTE 1NOTE 25GMM-REGISTEREDIn 5GMM-REGISTERED, when 5GMM-CONNECTED mode is left and if the NW does not indicate support for strictly periodic registration timer as specified in subclause 5.3.7.If the network indicates support for strictly periodic registration timer, T3512 is started after the successful completion of registration update procedure. T3512 is restarted if it expires in 5GMM-CONNECTED mode as specified in subclause 5.3.7.When entering state 5GMM-DEREGISTEREDWhen entering 5GMM-CONNECTED mode if the NW does not indicate support for strictly periodic registration timer as specified in subclause 5.3.7.In 5GMM-IDLE mode, Initiation of the periodic registration procedure if the UE is not registered for emergency services.In 5GMM-CONNECTED mode, restart the timer T3512.Locally deregister if the UE is registered for emergency services

[0054] NOTE 1: The value of this timer is provided by the network operator during the registration procedure.

[0055] NOTE 2: The default value of this timer is used if the network does not indicate a value in the REGISTRATION ACCEPT message and the UE does not have a stored value for this timer.

[0056] Table 2 depicts the 5GC Mobility Management Timers, AMF side.

[0057] Timer Num.Timer valueStateCause of startNormal stopOn ExpiryImplicit de-registration timerNOTE 2All except 5GMM-DEREGISTEREDThe mobile reachable timer expires while the network is in 5GMM-IDLE mode.Entering 5GMM-IDLE mode over 3GPP access if the MICO mode is activated and strictly periodic monitoring timer is not running.The strictly periodic monitoring timer expires while the network is in 5GMM-IDLE modeN1 NAS signalling connection establishedImplicitly de-register the UE on 1stexpiryMobile reachable timerNOTE 1All except 5GMM-DEREGISTEREDEntering 5GMM-IDLE modeN1 NAS signalling connection establishedNetwork dependent, but typically paging is halted on 1stexpiry, and start implicit de-registration timer, if the UE is not registered for emergency services.Implicitly de-register the UE which is registered for emergency services

[0058] NOTE 1: The default value of this timer is 4 minutes greater than the value of timer T3512. If the UE is registered for emergency services, the value of this timer is set equal to the value of timer T3512. If the T3346 value provided in the mobility management messages is greater than the value of the timer T3512, the AMF sets the mobile reachable timer and the implicit de-registration timer such that the sum of the timer values is greater than the value of timer T3346.

[0059] NOTE 2: The value of this timer is network dependent. If MICO is activated, the default value of this timer is 4 minutes greater than the value of timer T3512.

[0060] Table 3 depicts the EPS mobility management timers, UE side.

[0061] Timer Num.Timer valueStateCause of startNormal stopOn ExpiryT3412Default 54 min.NOTE 2NOTE 5EMM-REGISTEREDIn EMM-REGISTERED, when EMM-CONNECTED mode is left.When entering state EMM-DEREGISTERED or when entering EMM-CONNECTED mode.Initiation of the periodic tracking area updating procedure if the UE is not attached for emergency bearer services or T3423 started under the conditions as specified in clause 5.3.5.Implicit detach from network if the UE is attached for emergency bearer services.

[0062] NOTE 2: The value of this timer is provided by the network operator during the attach and tracking area updating procedures.

[0063] NOTE 3: The value of this timer may be provided by the network in the ATTACH ACCEPT message and TRACKING AREA UPDATE ACCEPT message. The default value of this timer is identical to the value of T3412.

[0064] NOTE 5: The default value of this timer is used if the network does not indicate a value in the TRACKING AREA UPDATE ACCEPT message and the UE does not have a stored value for this timer.

[0065] Table 4 depicts the EPS mobility management timers, network side.

[0066] Timer Num.Timer valueStateCause of startNormal stopON THE1st, 2nd, 3rd, 4th EXPIRY (NOTE 1)Mobile reachableNOTE 4All except EMM-DEREGISTEREDEntering EMM-IDLE modeNAS signalling connection establishedNetwork dependent, but typically paging is halted on 1st expiry if the UE is not attached for emergency bearer services.Implicitly detach the UE which is attached for emergency bearer services.Implicit detach timerNOTE 3All except EMM-DEREGISTEREDThe mobile reachable timer expires while the network is in EMM-IDLE modeNAS signalling connection establishedImplicitly detach the UE on 1st expiry

[0067] NOTE 3: The value of this timer is network dependent. If ISR is activated, the default value of this timer is 4 minutes greater than T3423.

[0068] NOTE 4: The default value of this timer is 4 minutes greater than T3412. If T3346 is larger than T3412 and the MME includes timer T3346 in the TRACKING AREA UPDATE REJECT message or SERVICE REJECT message, the value of the mobile reachable timer and implicit detach timer is set such that the sum of the timer values is greater than T3346. If the UE is attached for emergency bearer services, the value of this timer is set equal to T3412.

[0069] When the architectural option with MME / AMF onboard (MME lighter) (i.e., MME on the satellite) is used along with MME / AMF on ground (full MME / AMF), it is not clear as to how the EPS / 5GC Mobility Management timers at the UE or Network side (for example, MRT, PTAU (Periodic Tracking Area Update) timer or Timer 3412 or Periodic Registration Timer or T3512 and / or Implicit De-registration / Detach timer (IDT)) should be handled at the MME / AMF onboard or the MME / AMF on ground.

[0070] Further, it is not clear as to how the EPS / 5GC Mobility Management timers at the UE or Network side (for example, MRT, PTAU timer or Timer 3412 or Periodic Registration Timer or T3512 and / or IDT values are synced between the ground MME / AMF and the MME / AMF onboard different satellites.

[0071] Further, it is not clear as to how the UE context / parameters is maintained / synced between the MME-onboard / AMF-onboard and the MME-onground / AMF-onground.

[0072] Hence, there is a need in the art for solutions which will overcome the above mentioned drawback(s), among others.

[0073] The embodiments herein achieve disclose methods and systems for handling EPS / 5GC Mobility Management timers (for example, UE or Network side) (in an example, MRT (Mobile Reachable Timer), PTAU (Periodic Tracking Area Update) timer or Timer 3412 or Periodic Registration Timer or T3512 and / or IDT (Implicit De-registration / Detach timer) be handled at MME / AMF onboard or MME / AMF on ground, when the architectural option with MME / AMF onboard (for example, MME lighter) is used along with MME / AMF on ground (full MME / AMF). Referring now to the drawings, and more particularly to FIGS. 3 through 9, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0074] The following definitions and abbreviations have been referred to herein:

[0075] 3GPP: Third Generation Partnership Project

[0076] 4G-GUTI: 4G-Globally Unique Temporary Identifier

[0077] 5G-BRG: 5G Broadband Residential Gateway

[0078] 5GC: 5G Core

[0079] 5GCN: 5G Core Network

[0080] 5G-CRG: 5G Cable Residential Gateway

[0081] 5G-GUTI: 5G-Globally Unique Temporary Identifier

[0082] 5GMM: 5G Mobility Management

[0083] 5G-RG: 5G Residential Gateway

[0084] 5GS: 5G System

[0085] 5GSM: 5GS Session Management

[0086] 5G-S-TMSI: 5G S-Temporary Mobile Subscription Identifier

[0087] 5G-TMSI: 5G Temporary Mobile Subscription Identifier

[0088] 5QI: 5G QoS Identifier

[0089] ACS: Auto-Configuration Server

[0090] AKA: Authentication and Key Agreement

[0091] A-KID: AKMA Key Identifier

[0092] AKMA: Authentication and Key Management for Applications

[0093] AMBR: Aggregate Maximum Bit Rate

[0094] AMF: Access and Mobility Management Function

[0095] APN: Access Point Name

[0096] ARP: Allocation and Retention Policy

[0097] AS: Access Stratum

[0098] A-TID: AKMA Temporary Identifier

[0099] ATSSS: Access Traffic Steering, Switching and Splitting

[0100] AUSF: Authentication Server Function

[0101] CAG: Closed access group

[0102] CAG ID: Closed Access Group Identifier

[0103] CHAP: Challenge Handshake Authentication Protocol

[0104] CU: Centralized Unit

[0105] DC: Discontinuous Coverage

[0106] DisCo: Discontinuous Coverage

[0107] DL: Downlink

[0108] DND: Do not Disturb

[0109] DRX: Discontinuous Reception

[0110] DU: Distributed Unit

[0111] eDRX: Extended Discontinuous Reception

[0112] EHPLMN: Equivalent Home Public Land Mobile Network

[0113] EMM: EUTRA Mobility Management

[0114] eNB: Evolved Node-B

[0115] eNPN: Enhanced Non-Public Networks

[0116] EPC: Evolved Packet Core

[0117] EPLMN: Equivalent Public Land Mobile Network

[0118] EPS: Evolved Packet System

[0119] eSIM: embedded Subscriber Identity Module

[0120] E-UTRA: Evolved Universal Mobile Telecommunication Access

[0121] EUTRAN: Evolved Universal Mobile Telecommunication Access Network

[0122] FPLMN: Forbidden Public Land Mobile Network

[0123] FR: Frequency Range

[0124] GEO: Geostationary Orbit

[0125] GERAN: GSM Edge Radio Access Network

[0126] GERAN EC-GSM-IoT: GSM Edge Radio Access Network Extended Coverage -GSM-Internet of Things

[0127] gNB: Next generation Node-B

[0128] gNB - CU: Next generation Node-B Control Unit

[0129] gNB - DU: Next generation Node-B Distributive Unit

[0130] GPRS: General Packet Radio Service

[0131] GPS: Global Positioning System

[0132] GSM: Global System for Mobile Communication

[0133] HPLMN: Home Public Land Mobile Network

[0134] IAB: Integrated access and backhaul

[0135] IAB-UE: The part of the IAB node that supports the Uu interface towards the IAB-donor or another parent IAB-node (and thus manages the backhaul connectivity with either PLMN or SNPN it is registered with) is referred to as an IAB-UE.

[0136] LADN: Local Area Data Network

[0137] LCS: Location services

[0138] LEO: Low Earth Orbit

[0139] MBSR: Mobile Base Station Relay

[0140] MCC: Mobile Country Code

[0141] MCS: Mission Critical Service

[0142] ME: Mobile Equipment

[0143] MEC: Multi-Access Edge Computing

[0144] MEO: Medium Earth Orbit

[0145] MICO: Mobile Initiated Communication Only

[0146] MINT: Minimization of service interruption

[0147] MME: Mobility Management Entity

[0148] MNC: Mobile Network Code

[0149] MPS: Multimedia Priority Service

[0150] MS: Mobile Station. The present document makes no distinction between MS and UE.

[0151] NAS: Non-Access Stratum

[0152] NB-S1 Mode: Narrow Band with S1 Interface

[0153] NGAP: Next Generation Application Protocol

[0154] NG-RAN: Next Generation Radio Access Network

[0155] NPN: Non-Public Networks

[0156] NR: New Radio

[0157] NTN: Non Terrestrial Networks

[0158] NW: Network

[0159] OOS: Out of Service

[0160] OS Upgrade: Operating System Upgrade

[0161] PDN: Packet Data Network

[0162] PDU: Packet Data Unit

[0163] PLMN ID: Public Land Mobile Network Identity

[0164] PSM: Power Saving Mode

[0165] QoS: Quality Of Service

[0166] RAT: Radio Access Technology

[0167] RPLMN: Registered Public Land Mobile Network

[0168] RRC: Radio Resource Control

[0169] RU: Registration Update

[0170] SAT: Satellite

[0171] Satellite: An artificial body placed in orbit round the earth or moon or another planet in order to collect information or for communication.

[0172] Satellite Constellation: Group of satellites, placed in orbit round the earth or moon or another planet in order to collect information or for communication.

[0173] 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.

[0174] SIM: Subscriber Identity Module

[0175] SNPN: Standalone Non-Public Networks

[0176] SUCI: Subscription Concealed Identifier

[0177] SW: Software

[0178] TAC: Tracking Area Code

[0179] TAI: Tracking Area Identity

[0180] TAU: Tracking Area Update

[0181] TER: Terrestrial

[0182] TN: Terrestrial Networks

[0183] UCU: UE Configuration Update

[0184] UDM: Unified Data Management Function

[0185] UE: User Equipment

[0186] UL: Uplink

[0187] ULI: User Location Information

[0188] UPU: UE Parameters Update

[0189] USIM: Universal Subscriber Identification Module

[0190] Uu: The radio interface between the UE and the Node B

[0191] VMR: Vehicle Mounted Relay

[0192] VPLMN: Visited Public Land Mobile Network

[0193] WB-S1 Mode : Wide Band with S1 Interface

[0194] Visited PLMN (VPLMN): This is a PLMN different from the HPLMN (if the EHPLMN list is not present or is empty) or different from an EHPLMN (if the EHPLMN list is present).

[0195] Allowable PLMN: In the case of an MS operating in MS operation mode A or B, this is a PLMN which is not in the list of "forbidden PLMNs" in the MS. In the case of an MS operating in MS operation mode C or an MS not supporting A / Gb mode and not supporting Iu mode, this is a PLMN which is not in the list of "forbidden PLMNs" and not in the list of "forbidden PLMNs for GPRS service" in the MS.

[0196] Available PLMN: PLMN(s) in the given area which is / are broadcasting capability to provide wireless communication services to the UE.

[0197] Camped on a cell: The MS (ME if there is no SIM) has completed the cell selection / reselection process and has chosen a cell from which it plans to receive all available services. Note that the services may be limited, and that the PLMN or the SNPN may not be aware of the existence of the MS (ME) within the chosen cell.

[0198] EHPLMN: Any of the PLMN entries contained in the Equivalent HPLMN list.

[0199] Equivalent HPLMN list: To allow provision for multiple HPLMN codes, PLMN codes that are present within this list shall replace the HPLMN code derived from the IMSI for PLMN selection purposes. This list is stored on the USIM and is known as the EHPLMN list. The EHPLMN list may also contain the HPLMN code derived from the IMSI. If the HPLMN code derived from the IMSI is not present in the EHPLMN list then it shall be treated as a Visited PLMN for PLMN selection purposes.

[0200] Home PLMN: This is a PLMN where the MCC and MNC of the PLMN identity match the MCC and MNC of the IMSI.

[0201] Registered PLMN (RPLMN): This is the PLMN on which certain LR(location registration which is also called as registration procedure) outcomes have occurred. In a shared network the RPLMN is the PLMN defined by the PLMN identity of the CN operator that has accepted the LR.

[0202] Registration: This is the process of camping on a cell of the PLMN or the SNPN and doing any necessary LRs.

[0203] UPLMN : PLMN / access technology combination in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);

[0204] OPLMN : PLMN / access technology combination in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order)

[0205] Feeder Link: Feeder link can be defined as a wireless link between the NTN Gateway and the satellite.

[0206] Service Link: Service link is the radio link between a user equipment (UE) and a Satellite.

[0207] Examples of the NAS messages can be, but not limited to, REGISTRATION REQUEST message; DEREGISTRATION REQUEST message; SERVICE REQUEST message; CONTROL PLANE SERVICE REQUEST; IDENTITY REQUEST; AUTHENTICATION REQUEST; AUTHENTICATION RESULT; AUTHENTICATION REJECT; REGISTRATION REJECT; REGISTRATION ACCEPT; DEREGISTRATION ACCEPT; SERVICE REJECT; SERVICE ACCEPT; UE CONFIGURATION UPDATE command, UE PARAMETERS UPDATE command, and so on.

[0208] The term 5GMM sublayer states in this embodiment are at least one of the below:

[0209] 1) 5GMM-NULL

[0210] 2) 5GMM-DEREGISTERED

[0211] - a) 5GMM-DEREGISTERED.NORMAL-SERVICE

[0212] - b) 5GMM-DEREGISTERED.LIMITED-SERVICE

[0213] - c) 5GMM-DEREGISTERED.ATTEMPTING-REGISTRATION

[0214] - d) 5GMM-DEREGISTERED.PLMN-SEARCH

[0215] - e) 5GMM-DEREGISTERED.NO-SUPI

[0216] - f) 5GMM-DEREGISTERED.NO-CELL-AVAILABLE

[0217] - g) 5GMM-DEREGISTERED.eCALL-INACTIVE

[0218] - h) 5GMM-DEREGISTERED.INITIAL-REGISTRATION-NEEDED

[0219] 3) 5GMM-REGISTERED-INITIATED

[0220] 4) 5GMM-REGISTERED

[0221] - a) 5GMM-REGISTERED.NORMAL-SERVICE

[0222] - b) 5GMM-REGISTERED.NON-ALLOWED-SERVICE

[0223] - c) 5GMM-REGISTERED.ATTEMPTING-REGISTRATION-UPDATE

[0224] - d) 5GMM-REGISTERED.LIMITED-SERVICE

[0225] - e) 5GMM-REGISTERED.PLMN-SEARCH

[0226] - f) 5GMM-REGISTERED.NO-CELL-AVAILABLE

[0227] - g) 5GMM-REGISTERED.UPDATE-NEEDED

[0228] 5) 5GMM-DEREGISTERED-INITIATED

[0229] 6) 5GMM-SERVICE-REQUEST-INITIATED

[0230] In this embodiment, the term EMM sublayer states are at least one of the below:

[0231] 1) EMM-NULL

[0232] 2) EMM-DEREGISTERED

[0233] - a) EMM-DEREGISTERED.NORMAL-SERVICE

[0234] - b) EMM-DEREGISTERED.LIMITED-SERVICE

[0235] - c) EMM-DEREGISTERED.ATTEMPTING-TO-ATTACH

[0236] - d) EMM-DEREGISTERED.PLMN-SEARCH

[0237] - e) EMM-DEREGISTERED.NO-IMSI

[0238] - f) EMM-DEREGISTERED.ATTACH-NEEDED

[0239] - g) EMM-DEREGISTERED.NO-CELL-AVAILABLE

[0240] - h) EMM-DEREGISTERED.eCALL-INACTIVE

[0241] 3) EMM-REGISTERED-INITIATED

[0242] 4) EMM-REGISTERED

[0243] - a) EMM-REGISTERED.NORMAL-SERVICE

[0244] - b) EMM-REGISTERED.ATTEMPTING-TO-UPDATE

[0245] - c) EMM-REGISTERED.LIMITED-SERVICE

[0246] - d) EMM-REGISTERED.PLMN-SEARCH

[0247] - e) EMM-REGISTERED.UPDATE-NEEDED

[0248] - f) EMM-REGISTERED.NO-CELL-AVAILABLE

[0249] - g) EMM-REGISTERED.ATTEMPTING-TO-UPDATE-MM

[0250] - h) EMM-REGISTERED.IMSI-DETACH-INITIATED

[0251] 5) EMM-DEREGISTERED-INITIATED

[0252] 6) EMM-TRACKING-AREA-UPDATING-INITIATED

[0253] 7) EMM-SERVICE-REQUEST-INITIATED

[0254] The term RAT as defined in this embodiment can be one of the following: NG-RAN, 5G, 4G, 3G, 2G, EPS, 5GS, NR, NR in unlicensed bands, NR (LEO) satellite access, NR (MEO) satellite access, NR (GEO) satellite access, NR (OTHERSAT) satellite access, NR RedCap, E-UTRA, E-UTRA in unlicensed bands, NB-IoT, WB-IoT, LTE-M, and so on.

[0255] 5GS registration type can be initial registration, mobility registration updating, periodic registration updating, emergency registration, SNPN onboarding registration, disaster roaming initial registration; disaster roaming mobility registration updating, and so on.

[0256] not set the registration type to disaster roaming initial registration or disaster roaming mobility registration updating means 5GS registration type is set to value other than "disaster roaming initial registration" or ""disaster roaming mobility registration updating" at least one of initial registration, mobility registration updating, periodic registration updating, emergency registration, SNPN onboarding registration, and so on.

[0257] PLMN selection as per 23.122 without RPLMN:

[0258] The MS selects and attempts registration on any PLMN / access technology combinations, if available and allowable, in the following order:

[0259] - either the HPLMN (if the EHPLMN list is not present or is empty) or the highest priority EHPLMN that is available (if the EHPLMN list is present);

[0260] - each PLMN / access technology combination in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);

[0261] - each PLMN / access technology combination in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order);

[0262] - other PLMN / access technology combinations with received high quality signals in random order; and

[0263] - other PLMN / access technology combinations in order of decreasing signal quality.

[0264] PLMN selection as per 23.122 with RPLMN:

[0265] The MS selects and attempts registration on any PLMN / access technology combinations, if available and allowable, in the following order:

[0266] - either the RPLMN or the Last registered PLMN;

[0267] - either the HPLMN (if the EHPLMN list is not present or is empty) or the highest priority EHPLMN that is available (if the EHPLMN list is present);

[0268] - each PLMN / access technology combination in the "User Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order);

[0269] - each PLMN / access technology combination in the "Operator Controlled PLMN Selector with Access Technology" data file in the SIM (in priority order) or stored in the ME (in priority order);

[0270] - other PLMN / access technology combinations with received high quality signals in random order; and

[0271] - other PLMN / access technology combinations in order of decreasing signal quality.

[0272] The Satellite System or Satellite Access as used or defined in this embodiment is applicable for both 5G system with satellite access and / or 4G system with satellite access or any RAT with satellite access. The terms Satellite 3GPP access, Satellite access, Satellite Access Network, NR Satellite Access Network, Satellite NG-RAN Access Technology and NR Satellite access have been interchangeably used and have the same meaning. The methods, issues or solutions disclosed in this embodiment are explained using NR satellite access or Satellite NG-RAN Access Technology as an example and are not restricted or limited to NR Satellite access only. However, the solutions proposed in this embodiment are also applicable for Satellite E-UTRAN access Technology, NB (Narrow Band)-S1 mode or WB (Wide Band)-S1 mode via satellite E-UTRAN access and / or NB-IOT (NarrowBand Internet Of Things), or WB-IOT (WideBand Internet Of Things) Satellite Access / Architecture.

[0273] The solutions which are defined for NR (5GC) are also applicable to legacy RATs like E-UTRA / LTE, the corresponding CN entities need to be replaced by LTE entities; for example, AMF with MME, g-nodeB with e-nodeB, UDM with HSS, and so on; but principles of the solution remain the same.

[0274] The solutions which are defined for LTE (EPC / EPS / 4G) are also applicable for other RATs as defined in this embodiment (for example, NR / 5GS / 5GC / 5G), the corresponding CN entities needs to be replaced by NR entities; for example, MME with AMF, e-nodeB with g-nodeB, HSS with UDM, and so on; but principles of the solution remains same.

[0275] An example list of NAS messages can be, but not limited to, REGISTRATION REQUEST message; DEREGISTRATION REQUEST message; SERVICE REQUEST message; CONTROL PLANE SERVICE REQUEST; IDENTITY REQUEST; AUTHENTICATION REQUEST; AUTHENTICATION RESULT; AUTHENTICATION REJECT; REGISTRATION REJECT; DEREGISTRATION ACCEPT; SERVICE REJECT; SERVICE ACCEPT, and so on.

[0276] The network as referred to herein can be explained using any 5G Core Network Function (for example, AMF). However, the network could be any 5G / EUTRAN Core Network Entity like AMF / SMF / MME / UPF or the Network could be any 5G / EUTRAN RAN Entity like eNodeB (eNB) or gNodeB (gNB) or NG-RAN, and so on.

[0277] The messages used or indicated in this embodiment are shown as an example. The messages could be any signalling messages between the UE and the network functions / entities or between different network functions / entities.

[0278] The term area / location / geographical area are used in this embodiment may refer to any of cell / cell ID, TAC / TAI, PLMN ,MCC / MNC, Latitude / longitude, CAG cell or any geographical location / coordinate.

[0279] The methods, issues or solutions disclosed in this embodiment are explained using NR access or NG-RAN Access Technology as an example and is not restricted or limited to NR access only. However, the solutions proposed in this embodiment are also applicable for E-UTRAN access Technology, NB (Narrow Band)-S1 mode or WB (Wide Band)-S1 mode via E-UTRAN access and / or NB-IOT (NarrowBand Internet Of Things) or WB-IOT (WideBand Internet Of Things) Access / Architecture.

[0280] The solutions which are defined for NR (5GC) are also applicable to legacy RATs (such as, but not limited to, E-UTRA / LTE), the corresponding CN entities need to be replaced by LTE entities (for example, AMF with MME, g-nodeB with e-nodeB, UDM with HSS, and so on); however, principles of the solution remain the same.

[0281] The Network used in this embodiment is explained using any 5G Core Network Function (for example, AMF). However, the network could be any 5G / EUTRAN Core Network Entity (such as, but not limited to, AMF / SMF / MME / UPF) or the Network could be any 5G / EUTRAN RAN Entity (such as, but not limited to, eNodeB (eNB) or gNodeB (gNB) or NG-RAN, and so on).

[0282] The messages used or indicated in this embodiment are shown as an example. The messages could be any signalling message between the UE and the Network Functions / Entities or between different Network functions / entities.

[0283] The terms 'camp' and 'register' are used interchangeably and have the same meaning.

[0284] The terms wait timer, DisCo wait timer, Discontinuous Coverage wait timer, Random timer, Random wait timer, DCW Timer are all used interchangeably and have the same meaning.

[0285] The terms wait range, Disco Wait Range, Discontinuous Coverage Wait Range, and DCW Range are all used interchangeably and have the same meaning.

[0286] The term area as used in this embodiment may refer to any one or more of cell / cell ID, TAC / TAI, PLMN, MCC / MNC, Latitude / longitude, any CAG / CAG identifier or any geographical location / coordinate.

[0287] The UE location or UE area as used in this embodiment may refer to any one or more of cell / cell ID, TAC / TAI, PLMN, MCC / MNC, Latitude / longitude, any CAG / CAG identifier, or any geographical location / coordinate.

[0288] 3GPP TS 24.501 or 3GPP TS 24.301 provides a list of possible NAS messages. 3GPP TS 38.331 or 3GPP TS 36.331 provides a list of possible AS messages.

[0289] The cause names in this embodiment are for illustration purposes and it can have any name. The NAS and AS messages described herein are only for illustration purposes, the NAS and AS message can be any NAS or AS messages as per the protocol between the UE and the AMF / MME, or the UE and the gNB (NG-RAN / any RAN node) / eNB.

[0290] In this embodiment, the term 'satellite' is used herein interchangeably with 5G or 4G system with satellite access and is used to represent any Satellite(s) or constellation of Satellites(s) or any aerial body / satellite in any of the Satellite orbits (for example, LEO / MEO / GEO / HEO, and so on) or any 5G system with Satellite Access or 4G System with Satellite Access or any RAN Entity or Core Network Entity or any Network Function(s) associated with the Satellite Access / RAT / PLMN / Network.

[0291] The terms 'MME / AMF On-board', 'MME-onboard', 'MME-onboard / AMF-onboard' and 'MME / AMF-lighter; are used interchangeably herein, and have the same meaning.

[0292] The terms 'MME-Onground / AMF-onground', 'MME-onground' and 'MME / AMF-onground' are used interchangeably herein, and have the same meaning.

[0293] The terms 'SAT', and 'Satellite' are used interchangeably herein, and have the same meaning.

[0294] Serving satellite: a satellite providing the satellite access to a UE. In the case of NGSO (Non-Geostationary Satellite Orbit), the serving satellite is always changing due to the nature of the constellation.

[0295] Store and Forward Satellite operation: An operation mode that provides a communication service to the UE, when the serving satellite has a discontinuous connection to the ground network and such connection is not available when the satellite is interacting with the UE; i.e., it is an operation mode of a 5G system with satellite access where the 5G system can provide some level of service (in storing and forwarding the data) when satellite connectivity is intermittently / temporarily unavailable; for example, to provide communication service for UEs under satellite coverage without a simultaneous active feeder link connection to the ground segment.

[0296] S&F Mode: The mode in which the UE, RAN and core network entities perform Store and Forward Satellite operation.

[0297] IDT: Implicit Detach Timer / Implicit Deregistration timer.

[0298] MRT: Mobile Reachable Timer.

[0299] In an embodiment herein, the term satellite may refer to any of the LEO, MEO, GEO, and HEO Satellites.

[0300] In an embodiment herein, MME / AMF onboard is used as an example. It can be any other 5GC network function (NF) or EPC CN Node or any new function. It may be with full functionality or limited functionality, to fulfil the requirement of S / F operation.

[0301] The term 'satellite' as referred to herein can refer to the satellite and the NF onboard the satellite.

[0302] In an embodiment herein, the ground MME or AMF are shown as example core network elements or network functions, however, this can be any other core network element or network function.

[0303] FIG. 3 depicts the architecture of the satellite communication network, according to an embodiment of the disclosure. At time T0, consider that the Satellite 101 has MME-onboard (MME-light or MME-Lighter) or AMF-onboard or any other network entity 101A. an MME onground / AMF onground 102, the S-GW / P-GW 103, and the HSS / UDM 104 are present near the ground station. Other Network entities may or may not be onboard. FIGs. 4A, 4B, and 4C depict the satellite network architecture at times T0, T1, and T2 respectively. FIG. 4A depicts the satellite network architecture at time T0, according to an embodiment of the disclosure. FIG 4B depicts the satellite network architecture at time T1, according to an embodiment of the disclosure. FIG 4C depicts the satellite network architecture at time T2, according to an embodiment of the disclosure. The Satellite has MME-onboard or AMF-onboard or any other network entity to support S&F registration / attach procedure.

[0304] FIG. 5 depicts an example scenario, wherein the Tracking Area Update (or Mobility / Periodic Registration Update procedure / flow) flow is successful with MME / AMF on ground running MRT+IDT timers, according to an embodiment of the disclosure. Consider that the UE 105 is registered via satellite access with EPC / 5GC. The ground MME / AMF 102 runs the timers MRT, IDT for the UE 105. On expiry of the PTAU / Periodic Registration Update timer, the UE 105 sends a Periodic Tracking Area Update Request message / Periodic registration update message to the network (satellite cell). The satellite 101 stores and / or processes the message received from the UE 105, and in step 503, sends a local acknowledgement (for example, any AS / NAS signalling message / indication to indicate that the message is successfully received) to the UE 105. The UE 105 runs a first timer (say, tm1) to receive local ack from the network / satellite / AMF or MME onboard 101 / 101A. If the UE 105 does not receive the local ack within the first timer (for example, if the timer expires), the UE 105 attempts to send the TAU request message again. In an embodiment of the disclosure, the UE 105 may attempt the aforementioned procedure (or any AS / NAS signalling procedure) for a maximum pre-defined number for attempts (for example, five attempts) and assume / declare the procedure to be a failure if the attempt / re-attempt counter reaches the pre-defined maximum value. Optionally, the UE 105 may start a new AS / NAS signalling procedure (for example, Attach / Registration procedure) at the end of this procedure. In an embodiment of the disclosure, the satellite network function / core network entity (for example, the onboard MME / AMF 101A) sends a TAU accept / Periodic registration accept / reject or any valid response (for example, Accept / Reject) for the procedure to the UE 105 without going to the ground station (MME / AMF onground 102). The MME / AMF onboard 101A may run a copy of the MRT+IDT timer with the same values as ground MME / AMF 102, and use the MRT+IDT timer to decide whether to accept or reject the TAU.

[0305] In an embodiment of the disclosure, when it reaches the ground station location after x time (i.e., the feeder link is established between satellite and ground station), the satellite 101 sends the Periodic Tracking Area Update Request message / Periodic registration update message to the ground MME / AMF 102. The ground MME / AMF 102 processes the request received from the AMF / MME on-board 101A. The ground MME / AMF 102 accepts the TAU / PRU request, if the TAU / PRU request is received before the expiry of MRT+IDT at the ground MME / AMF 102. In an embodiment of the disclosure, the MME / AMF-onground 102 may reject the TAU / PRU request, if the TAU / PRU request has not been received before the expiry of MRT+IDT at the ground MME / AMF 102, or the MRT+IDT timer being run at the MME / AMF-onground 102 has expired. The MRT+IDT timer at the MME / AMF onground 102 is set / adjusted such that it is greater than the SUM of PTAU / PRU timer assigned to the UE 105, and the time taken by the satellite 101 for getting feeder link with the ground station again after the UE 105 sends the PTAU / PRU message to the MME / AMF on-board 101A (i.e., the time taken between TAU received from the UE 105 and the time when the satellite reaches the location where the feeder link becomes available again to connect with the ground station).

[0306] In an embodiment of the disclosure, the MRT+IDT timer at the MME / AMF onground 102 is set / adjusted such that it is greater than the SUM of PTAU / PRU timer assigned to the UE 105 and the sum / greater of the time taken for the UE 105 to get / find a satellite coverage after the Periodic TAU / MRU / PRU timer has expired or service link is not available (for example, the UE 105 is in discontinuous coverage) and the time taken by the satellite for getting feeder link with ground station again after the UE 105 sends the PTAU / PRU message to the MME / AMF on-board 101A (i.e., the time taken between TAU received from the UE 105 and the time when the satellite 101 reaches the location where the feeder link becomes available again to connect with the ground station). The satellite 101 delivers the TAU / periodic registration accept / reject to the UE 105 once the service link has been established again. The TAU / periodic registration accept / reject may be delivered by the same satellite, or a different satellite. The UE 105 runs a second timer (tm2) to receive the TAU accept or reject / Registration accept or reject from the AMF / MME onboard 101A.

[0307] In an example, the UE 105 registers with 5GC / EPC CN using satellite access at 10 AM. The satellite reaches the ground station; i.e., feeder link is established at 10:10 AM (10 minutes delay due to feeder link non-availability). The AMF / MME on ground 102 accepts the attach request / registration request, and sends the attach accept / registration accept with PTAU / PRU timer of 60 minutes to the UE 105. The UE 105 receives Registration / attach accept at 10:30 AM from satellite (20 minutes delay due to the service link not established with the UE 105 again, total 30 minutes delay). The UE 105 is assigned a PTAU timer value of 60 minutes. At 11:30 AM, the UE 105 gets into connected mode, and sends a PTAU message to the satellite MME / AMF 101A. The satellite 101 sends a local acknowledgement to the UE 105, and the UE 105 gets into IDLE mode. The satellite 101 delivers to the ground MME 102 at 11.40; i.e., PTAU + 10 minutes (delay due to no feeder link availability) + 20 minutes (delay due to service link not established with the UE again) from registration accept sent by the AMF / MME onground 102. If the AMF / MME onground 102 does not receive PTAU / PRU before 11:40, then the AMF onground 102 can start the IDT. The PTAU timer is started, on the UE 105 entering the IDLE state.

[0308] In summary, the MME / AMF-onground 102 should run the MRT value of at least one of sum of the periodic timer given to the UE 105, maximum expected service link availability time (i.e., the time when the service link will be available from the current not available status), and expected maximum feeder link availability time (i.e., the time when the feeder link available from current not available status).

[0309] The maximum expected service link availability time (for example, from the UE 105 and / or Network / Satellite or from both) and the expected maximum feeder link availability time can also be added to the IDT, or the MRT, or both.

[0310] Overall, this expected maximum feeder link availability time and maximum expected service link availability time are considered by the MME / AMF before deregistering the UE (i.e. either as part of MRT or as part of IDT or it can be an independent timer(s)) and continue to hold the context of the UE 105 assuming there will be delay in the UE 105 connecting to the network due to expected maximum feeder link availability time and maximum expected service link availability time; i.e., in general, if PTAU is given to the UE 105, then the network runs MRT + IDT. Now, the network (if it has given PTAU timer to the UE) runs MRT + IDT + expected maximum feeder link availability time + maximum expected service link availability time. Optionally, the network may decide to not consider one of the expected maximum feeder link availability time and maximum expected service link availability time values; for example, the network may set the values to zero or not take one of them into consideration.

[0311] FIG. 6 depicts an example scenario, wherein the Tracking Area Update flow is successful with MME / AMF onboard all satellites running MRT+IDT timers, according to an embodiment of the disclosure. Consider that the UE 105 is registered via satellite access with the EPC / 5GC. The MME / AMF onboard 101A runs the timers MRT, IDT for the UE 105. On expiry of the PTAU / periodic Registration Update timer, the UE 105 sends a Periodic Tracking Area Update Request message / periodic registration update message to the network (satellite cell) 101. The satellite 101 processes the PTAU / periodic Registration Update request from the UE 105 and sends the PTAU accept / PRU accept / reject or any valid response (for example, Accept / Reject) for the procedure to the UE 105. The satellite 101 provides the PTAU timer to the UE 105 in a registration accept and sets the timer MRT+IDT values, wherein the timer MRT+IDT value is greater than the sum of the PTAU timer and the round trip time between the UE 105 and the ground station.

[0312] In an embodiment of the disclosure, the MME / AMF-onground 102 may reject the TAU / PRU request, if the TAU / PRU request has not been received before the expiry of MRT+IDT at the ground MME / AMF 102 or the MRT+IDT timer being run at the MME / AMF-onground 102 has expired. On the satellite 101 reaching the ground station location after x time (i.e., the feeder link is established between the satellite and the ground station), the satellite 102 updates the MRT+IDT timer with the ground station or indicates that the UE 105 came into connected mode (optionally, the last time that the UE 105 came into connected mode or when the UE 105 entered IDLE state) at (current time - x) duration or just indicate to the ground AMF / MME 102 that the UE 105 had come into the connected state and then entered the IDLE state or indicate new updated timers like MRT and IDT values. The MRT and IDT values are calculated as discussed in this embodiment as part of other solutions. The ground MME / AMF 102 stores the MRT+IDT timer values received from the AMF / MME onboard 101A. The ground MME / AMF 102 updates the timer values with all other satellites for the UE 105, as and when the feeder link is established with the respective satellite, or the ground MME / AMF 102 restarts the respective MRT and IDT timers based on the indication. The ground MME / AMF 102 may provide new updated MRT and IDT timer values to the MME / AMF onboard 101A.

[0313] In an example, the UE 105 sends a registration request / attach request with 5GC / EPC CN using satellite access at 10 AM. The satellite 101 processes the registration request / attach request received from the UE 105, and sends the Registration accept / attach accept to the UE 105 along with the PTAU timer (60 mins). The MME / AMF onboard 101A sets the MRT+IDT timer as 90 mins (PTAU 60 mins + feeder link delay+ service link delay). The satellite 101 moves and a feeder link is established at 10:10 AM (10 mins delay due to feeder link non-availability). The AMF / MME onboard 101A informs the AMF / MME on ground 102 about MRT+IDT timer values for the UE 105. When other satellites establish feeder link availability with the ground station, the MRT+IDT value is synced in the MME / AMF onboard the satellite. By 10:30 AM, all satellites have synced the MRT+IDT timer values.

[0314] In an example, the onboard MME / AMF 101A informs the ground MME / AMF 102 that the UE 105 has entered IDLE state after being in connected state. Due to this, the ground MME / AMF 102 restarts the MRT and IDT timers.

[0315] FIG. 7 depicts the modified NAS and AS procedures between UE and CN entities / Network Functions, according to an embodiment of the disclosure. All procedures which do not need to interact with the HSS / UDM 104 (or any other core network entity present on ground) can be executed by the MME / AMF on board the satellite 101A. The timers for such procedures will not be affected. Examples of such procedures are, but not limited to,

[0316] a) Periodic Tracking Area Update procedure or Periodic Registration Update procedure.

[0317] b) Mobility related aspects like eDRX, Active timer etc.

[0318] c) Paging, Service request, extended service request, CPSR etc.

[0319] d) UE capability update procedure.

[0320] e) UE configuration Update procedure.

[0321] f) UE Parameters Update.

[0322] All procedures which need to interact with the HSS / UDM 104 (or any other core network entity present on ground) can be executed between the MME / AMF on board the satellite. The timers for such procedures will be affected considering the round trip time / feeder link availability (delay) time.

[0323] The examples of such procedures are:

[0324] a) Attach or Registration

[0325] b) Detach or De-Registration

[0326] In an embodiment of the disclosure, the MME / AMF-onground 102 may configure the Satellite 101 or the MME / AMF-Onboard 101A with a UE context timer. The MME / AMF-onground 102 may configure the UE context timer on the only satellite 101 or MME / AMF-Onboard 101A serving the UE (for example, Single Satellite case) or the UE context timer can be configured for all the satellites or MME / AMF-onboard serving the UE (i.e., the satellites or MME / AMF-onboard which may serve the UE at any point of time); for example, for a case where multiple satellites are serving the UE 105 and the UE context / parameters need to be maintained at different satellites or AMF / MME-onboard. The UE context timer can be configured on a per Satellite or per AMF / MME-onboard basis. The UE context timer can be configured on a per UE basis.

[0327] In an embodiment of the disclosure, the MME / AMF-ground 102 can configure the UE context timer on a satellite 101 or MME / AMF-board 101A for a set of UE(s) being served by that Satellite 101 or MME / AMF-onboard 101A. The value of UE context timer can be any predefined value (for example, the value of UE context timer can be a value lesser than the value of the periodic update timer or a value lesser than the sum of the MRT, and the IDT). The Satellite 101 or MME / AMF-onboard 101A may start / restart the UE context timer, optionally per UE, on the MME / AMF-onboard 101A syncing the UE context / parameter with the MME / AMF-onground 102.

[0328] In an embodiment of the disclosure, the MME / AMF-onboard 101A may start the UE context timer, if not running, whenever there is a change in the UE context / parameters from the UE side or the satellite. In an embodiment of the disclosure, the MME / AMF-onboard 101A may remember or maintain a flag / indication that the UE context / parameters have changed and has to be synced with the MME / AMF-onground 102. If the UE context timer is running and there is a change in the UE context / parameters, the satellite 101 or the MME / AMF-onboard 101A may sync the UE context / parameters with the MME / AMF-onground 102, and may re-start the UE context timer. If the UE context timer has expired, the MME / AMF-onboard 101A may sync the UE context / parameters with the MME / AMF-onground 102, optionally whenever feeder link is available, and may restart the UE context timer. In an embodiment of the disclosure, on expiry of the UE context timer, and if the MME / AMF-onboard is not able to or fails to sync UE context / parameter with the MME / AMF-onground, (for example, within some additional time till it gets feeder link availability), the MME / AMF-onboard 101A may delete the UE context / parameters and may optionally detach / deregister the UE.

[0329] Optionally, For single satellite case: Periodic timer and mobile reachable timer:

[0330] The mobile reachable timer value has to be increased at the network so that it takes into account delay(s) in serving the UE after the PTAU timer has expired at the UE; for example, MRT = PTAU timer given to UE + Maximum potential delay for MME-onboard to again serve the UE.

[0331] For multiple satellite case:

[0332] The MRT and IDT is run only at the MME-ground; i.e., MME-onboard the satellite does not run these timers. Each time that the UE 105 gets in connected mode with at least one of the onboard MME 101A, the onboard MME 101A informs the ground-MME 102, and then the ground MME 102 restarts the MRT. The MRT value has to be increased at the network, so that it takes into account the delay in receiving information from the onboard-MME 101A after the UE 101 has come to connected mode (including a case of PTAU procedure). For example, MRT = PTAU timer given to UE + Maximum potential delay for MME-onboard to connect with MME-ground after UE has come to connected mode (including a case of PTAU procedure). Each MME-onboard 101A also runs a MME-UE-context onboard timer, and on expiry of the MME-UE-context onboard timer, the MME-onboard 101A synchronizes the UE context with the MME-ground 102; i.e., the MME-onboard 101A fetches the latest context available with MME-ground 102.

[0333] FIG. 8 is a flowchart depicting a process for handling periodic registration for Store & Forward (S&F) services, according to an embodiment of the disclosure. In an operation 810, the MME 101A / 102 (which can be one of the MME-ongound 102, or the MME-onboard 101A) starts the MRT, and the IDT for a UE 105 using a first value. When the UE 105 is registered in S&F mode, the first value of a periodic registration update timer can be assigned to the UE 105. The MME 101A / 102 starts at least one of the MRT, the IDT, and the PTAU timer. The first value of the MRT for the UE 105 is a sum of the PTAU timer given to the UE 105, and a maximum potential delay for the MME-onboard to connect with the MME-ground after the UE 105 has come to connected mode. The first value of the MRT takes into account a delay in receiving information from the MME-onboard over the first value of MRT after the UE 105 has come to the connected mode. The sum of the first value of the MRT, and the IDT is greater than a sum of the PTAU timer given to the UE 105, and taking into account the time taken by the MME-onboard for getting a feeder link with the MME-ground again after the UE 105 sends a PTAU message to the MME-onboard. In an operation 820, the MME 101A / 102 (which can be one of the MME-ongound 102, or the MME-onboard 101A) starts the MRT, and the IDT for a UE 105 using a second value. When the UE 105 is not registered in S&F mode, the second value of a periodic registration update timer can be assigned to the UE 105. On the UE 105 coming into connected mode to the MME-onboard 101A (in an operation 830), in an operation 840, the MME-onboard 101A provides an indication to the MME-ground 102. On receiving an indication from the MME-onboard 101A, in an operation 850, the MME-ground 102 restarts the MRT for the UE 105. The MME-onboard 101A further runs a MME-UE-context onboard timer. The MME-onboard 101A further synchronizes a UE context with the MME-ground, on expiry of the MME-UE-context onboard timer. The various actions in method 800 may be performed in the order presented, in a different order or simultaneously. Further, in an embodiment of the disclosure, some actions listed in FIG. 8 may be omitted.

[0334] FIG. 9 illustrates a network entity according to an embodiment of the disclosure. In an embodiment of the disclosure, the network entity 900 may be the MME 110A / 102. The MME 110A / 102 may be one of the MME-onboard 101A, and the MME-onground 102. The network entity 900 (e.g., MME 101A / 102), as depicted, may comprise a processor 910, at least one memory 920, and at least one transceiver 930. However, all of the illustrated components are not essential. The network entity 900 may be implemented by more or less components than those illustrated in FIG. 9. In addition, the processor 910 and the transceiver 930 and the memory 920 may be implemented as a single chip according to an embodiment of the disclosure.

[0335] The processor 910 may include one or more processors or other processing devices that control the proposed function, process, and / or method. Operation of the network entity 900 may be implemented by the processor 910. The processor 910 can be at least one of a single processor, a plurality of processors, multiple homogeneous or heterogeneous cores, multiple Central Processing Units (CPUs) of different kinds, microcontrollers, special media, and other accelerators. The processor 910 may be an Application Processor (AP), a graphics-only processing unit such as a Graphics Processing Unit (GPU), a Visual Processing Unit (VPU), and / or an Artificial Intelligence (AI)-dedicated processor such as a Neural Processing Unit (NPU).

[0336] The transceiver 930 may include a RF transmitter for up-converting and amplifying a transmitted signal, and a RF receiver for down-converting a frequency of a received signal. However, according to an embodiment of the disclosure, the transceiver 930 may be implemented by more or less components than those illustrated in components.

[0337] The transceiver 930 may be connected to the processor 910 and transmit and / or receive a signal. The signal may include control information and data. In addition, the transceiver 930 may receive the signal through a wireless channel and output the signal to the processor 910. The transceiver 930 may transmit a signal output from the processor 910 through the wireless channel.

[0338] In an embodiment herein, the at least one transceiver 930 is configured to enable communication between the network entity 900 (e.g., MME 101A / 102), and at least one external entity (such as, but not limited to, another MME 101A / 102, one or more UEs 105, a ground station, and so on) through a network or cloud. The transceiver 930 through which the network entity 900 (e.g., MME 101A / 102) and the at least one external entity communicate may include wired and / or wireless communication medium compatible with one or more different communication protocols. The transceiver 930 may be configured for communication through a network. The network may comprise, but are not limited to, Global Positioning System (GPS), Global System for Mobile Communications (GSM), Local Area Network (LAN), Wireless Fidelity (Wi-Fi) compatibility, Bluetooth Low Energy (BLE), Near-field Communication (NFC), and so on. The wireless communication may further comprise one or more of Bluetooth, Zonal Intercommunication Global Standard (ZigBee), short-range wireless communication such as Ultra-wideband (UWB), medium-range wireless communication such as Wi-Fi, or long-range wireless communication such as Third Generation (3G), Fourth Generation (4G), or Worldwide Interoperability for Microwave Access (WiMAX), according to the usage environment.

[0339] The memory 920 may store the control information or the data included in a signal obtained by the network entity 900. The memory 920 may be connected to the processor 910 and store at least one instruction or a protocol or a parameter for the proposed function, process, and / or method. The memory 920 may include read-only memory (ROM) and / or random access memory (RAM) and / or hard disk and / or CD-ROM and / or DVD and / or other storage devices.

[0340] In the embodiment shown herein, the at least one memory 920 may comprise one or more volatile and non-volatile memory components that are capable of storing data and instructions to be executed. Examples of the at least one memory 920 can be, but are not limited to, NAND, embedded Multimedia Card (eMMC), Secure Digital (SD) cards, Universal Serial Bus (USB), Serial Advanced Technology Attachment (SATA), solid-state drive (SSD), and so on. The at least one memory 920 may also include one or more computer-readable storage media. Examples of 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 at least one memory 920 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 to mean that the at least one memory 920 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).

[0341] The processor 910 can start the MRT, and the IDT for the UE 105 using a first value. When the UE 105 is registered in S&F mode, the processor 910 can assign the first value of the periodic registration update timer to the UE 105. The processor 910 can start at least one of the MRT, the IDT, and the PTAU timer. The first value of the MRT for the UE 105 is a sum of the PTAU timer given to the UE 105, and a maximum potential delay for the MME-onboard to connect with the MME-ground after the UE 105 has come to connected mode. The first value of the MRT takes into account a delay in receiving information from the MME-onboard over the first value of MRT after the UE 105 has come to the connected mode. The sum of the first value of the MRT, and the IDT is greater than a sum of the PTAU timer given to the UE 105, and taking into account the time taken by the MME-onboard for getting a feeder link with the MME-ground again after the UE 105 sends a PTAU message to the MME-onboard. The first value used for MRT or IDT can have different values. For example, at the MME 101A, 102 the MRT can be 360 minutes, and IDT can be 10 minutes, and similarly the first value of the periodic registration update timer can be 60 minutes. In this example, the MME 101A, 102 is considering delaying in the information reaching till the ground network; for example, of 300 minutes.

[0342] The processor 910 can start the MRT, and the IDT for a UE 105 using a second value. The second value for the MRT or the IDT can be different value. For example, at the MME, the MRT can be 64 minutes, and the IDT can be 10 minutes, and similarly, the second value of the periodic registration update timer can be 60 minutes. In this example, the MME 101A, 102 is not considering the delay in reaching the information, because the message from the UE 105 will instantly reach the MME 101A, 102.

[0343] When the UE 105 is not registered in S&F mode, the processor 910 can assign the second value of a periodic registration update timer to the UE 105. On the UE 105 coming into connected mode to the MME-onboard 101A, the processor 910 of the MME-onboard 101A can provide an indication to the MME-ground 102 via the transceiver 930 of the MME-onboard 101A.

[0344] The first value and second value as referred to herein are used to indicate the values assigned to MRT, IDT or Periodic registration update timer and can be different when the UE 105 is registered in S&F mode and the UE is not registered in S&F mode.

[0345] On receiving an indication from the MME-onboard 101A via the transceiver 930 of the MME-onground 102, the processor 910 of the MME-onground 102can restart the MRT for the UE 105.

[0346] The processor 910 of the MME-onboard 101A can further run the MME-UE-context onboard timer. The processor 910 of the MME-onboard 101A can further a UE context with the MME-ground, on expiry of the MME-UE-context onboard timer.

[0347] FIG. 10 illustrates an UE according to an embodiment of the disclosure.

[0348] Referring to the FIG. 10, the UE 105 may include a processor 1010, a transceiver 1020 and a memory 1030. However, all of the illustrated components are not essential. The UE 105 may be implemented by more or less components than those illustrated in FIG. 10. In addition, the processor 1010 and the transceiver 1020 and the memory 1030 may be implemented as a single chip according to an embodiment of the disclosure.

[0349] The aforementioned components will now be described in detail.

[0350] The processor 1010 may include one or more processors or other processing devices that control the proposed function, process, and / or method. Operation of the UE 105 may be implemented by the processor 1010.

[0351] The transceiver 1020 may include a RF transmitter for up-converting and amplifying a transmitted signal, and a RF receiver for down-converting a frequency of a received signal. However, according to an embodiment of the disclosure, the transceiver 1020 may be implemented by more or less components than those illustrated in components.

[0352] The transceiver 1020 may be connected to the processor 1010 and transmit and / or receive a signal. The signal may include control information and data. In addition, the transceiver 1020 may receive the signal through a wireless channel and output the signal to the processor 1010. The transceiver 1020 may transmit a signal output from the processor 1010 through the wireless channel.

[0353] The memory 1030 may store the control information or the data included in a signal obtained by the UE 105. The memory 1030 may be connected to the processor 1010 and store at least one instruction or a protocol or a parameter for the proposed function, process, and / or method. The memory 1030 may include read-only memory (ROM) and / or random access memory (RAM) and / or hard disk and / or CD-ROM and / or DVD and / or other storage devices.

[0354] FIG. 11 is a flowchart illustrating a method performed by a first network entity on a ground network in a wireless communication system according to an embodiment of the disclosure.

[0355] In an embodiment of the disclosure, the first network entity performing the method 1100 may be a MME-ground 102. In operation 1110, the first network entity may receive, from the second network entity onboard a satellite, information for a UE indicating that the UE gets in a connected mode with the second network entity. In an embodiment of the disclosure, the second network entity may be a MME-onboard 101A.

[0356] In operation 1120, the first network entity may start a MRT associated with the UE based on the information for the UE. In an embodiment of the disclosure, a duration of the MRT may be equal to or larger than a duration of a periodic tracking area update timer for the UE. In an embodiment of the disclosure, the duration of the MRT may be determined based on a potential delay for the first network entity to communicate with the second network entity after the UE comes to the connected mode. In an embodiment of the disclosure, the duration of the MRT may be determined based on a sum operation of a maximum duration of the potential delay and a duration of a periodic tracking area update timer for the UE.

[0357] In an embodiment of the disclosure, the first network entity may receive, from the second network entity, information for at least one UE context based on an expiry of a MME-UE-context onboard timer at the second network entity.

[0358] FIG. 12 is a flowchart illustrating a method performed by a second network entity onboard a satellite in a wireless communication system according to an embodiment of the disclosure.

[0359] In an embodiment of the disclosure, the second network entity performing the method 1200 may be a MME-onboard 101A. In operation 1210, the second network entity may identify that a UE gets in a connected mode with the second network entity.

[0360] In operation 1220, the second network entity may transmit, to the first network entity on the ground network, information for the UE indicating that the UE gets in the connected mode with the second network entity. In an embodiment of the disclosure, the first network entity may be a MME-ground 102.

[0361] In an embodiment of the disclosure, the information for the UE may be a basis for starting a MRT associated with the UE at the first network entity. In an embodiment of the disclosure, a duration of the MRT may be equal to or larger than a duration of a periodic tracking area update timer for the UE. In an embodiment of the disclosure, the duration of the MRT may be determined based on a potential delay for the first network entity to communicate with the second network entity after the UE comes to the connected mode. In an embodiment of the disclosure, the duration of the MRT may be determined based on a sum operation of a maximum duration of the potential delay and a duration of a periodic tracking area update timer for the UE.

[0362] In an embodiment of the disclosure, the second network entity may start a MME-UE-context onboard timer. In an embodiment of the disclosure, the second network entity may transmit, to the first network entity, information for at least one UE context based on an expiry of the MME-UE-context onboard timer.

[0363] The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The elements include blocks which can be at least one of a hardware device, or a combination of hardware device and software module.

[0364] The embodiments disclosed herein describe methods and systems for handling EPS / 5GC Mobility Management timers (for example, UE or Network side) (in an example, MRT (Mobile Reachable Timer), PTAU (Periodic Tracking Area Update) timer or Timer 3412 or Periodic Registration Timer or T3512 and / or IDT (Implicit De-registration / Detach timer) be handled at MME / AMF onboard or MME / AMF on ground, when the architectural option with MME / AMF onboard (for example, MME lighter) is used along with MME / AMF on ground (full MME / AMF). Therefore, it is understood that the scope of the protection is extended to such a program and in addition to a computer readable means having a message therein, such computer readable storage means contain program code means for implementation of one or more steps of the method, when the program runs on a server or mobile deviceor any suitable programmable device. The method is implemented in at least one embodiment through or together with a software program written in e.g., Very high speed integrated circuit Hardware Description Language (VHDL) another programming language, or implemented by one or more VHDL or several software modules being executed on at least one hardware device. The hardware device can be any kind of portable device that can be programmed. The device may also include means which could be e.g., hardware means like e.g., an ASIC, or a combination of hardware and software means, e.g., an ASIC and an FPGA, or at least one microprocessor and at least one memory with software modules located therein. The method embodiments described herein could be implemented partly in hardware and partly in software. Alternatively, the disclosure may be implemented on different hardware devices, e.g., using a plurality of CPUs.

[0365] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments and examples, those skilled in the art will recognize that the embodiments and examples disclosed herein can be practised with modification within the scope of the embodiments as described herein.

Claims

1.A method performed by a first network entity on a ground network in a wireless communication system, the method comprising:receiving, from a second network entity onboard a satellite, information for a User Equipment (UE) indicating that the UE gets in a connected mode with the second network entity; andstarting a Mobile Reachable Timer (MRT) associated with the UE based on the information for the UE.2.The method of claim 1, wherein a duration of the MRT is equal to or larger than a duration of a periodic tracking area update timer for the UE.3.The method of claim 1, wherein a duration of the MRT is determined based on a potential delay for the first network entity to communicate with the second network entity after the UE comes to the connected mode.4.The method of claim 3, wherein the duration of the MRT is determined based on a sum operation of a maximum duration of the potential delay and a duration of a periodic tracking area update timer for the UE.5.The method of claim 1, further comprising:receiving, from the second network entity, information for at least one UE context based on an expiry of a Mobility Management Entity (MME)-UE-context onboard timer at the second network entity.6.A method performed by a second network entity onboard a satellite in a wireless communication system, the method comprising:identifying that a User Equipment (UE) gets in a connected mode with the second network entity; andtransmitting, to a first network entity on a ground network, information for the UE indicating that the UE gets in the connected mode with the second network entity,wherein the information for the UE is a basis for starting a Mobile Reachable Timer (MRT) associated with the UE at the first network entity.7.The method of claim 6, wherein a duration of the MRT is equal to or larger than a duration of a periodic tracking area update timer for the UE.8.The method of claim 6, wherein a duration of the MRT is determined based on a potential delay for the first network entity to communicate with the second network entity after the UE comes to the connected mode.9.The method of claim 8, wherein the duration of the MRT is determined based on a sum operation of a maximum duration of the potential delay and a duration of a periodic tracking area update timer for the UE.10.The method of claim 6, further comprising:starting a Mobility Management Entity (MME)-UE-context onboard timer; andtransmitting, to the first network entity, information for at least one UE context based on an expiry of the MME-UE-context onboard timer.11.A first network entity on a ground network in a wireless communication system, comprising:a transceiver; andat least one processor coupled to the transceiver and configured to:receive, from a second network entity onboard a satellite, information for a User Equipment (UE) indicating that the UE gets in a connected mode with the second network entity; andstart a Mobile Reachable Timer (MRT) associated with the UE based on the information for the UE.12.The first network entity of claim 11, wherein a duration of the MRT is equal to or larger than a duration of a periodic tracking area update timer for the UE.13.The first network entity of claim 11, wherein a duration of the MRT is determined based on a potential delay for the first network entity to communicate with the second network entity after the UE comes to the connected mode.14.The first network entity of claim 11, wherein the at least one processor is further configured to receive, from the second network entity, information for at least one UE context based on an expiry of a Mobility Management Entity (MME)-UE-context onboard timer at the second network entity.15.A second network entity onboard a satellite in a wireless communication system, comprising:a transceiver; andat least one processor coupled to the transceiver and configured to:identify that a User Equipment (UE) gets in a connected mode with the second network entity; andtransmit, to a first network entity on a ground network, information for the UE indicating that the UE gets in the connected mode with the second network entity, wherein the information for the UE is a basis for starting a Mobile Reachable Timer (MRT) associated with the UE at the first network entity.

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