Method and apparatus for handling estimated delivery time in store and forward mode in a wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). The present invention relates to a method and system for managing estimated delivery time (EDT) values in a store-and-forward (S&F) satellite communication network. The method includes receiving by the UE a first Non-Access Stratum (NAS) message from a first satellite. The method includes storing by the UE (102) the first EDT value associated with the first satellite (101) in a memory of the UE (102). The method includes receiving by the UE (102) the second NAS message from a second satellite. Further, the method includes storing by the UE (102) the second EDT value while maintaining the first EDT value stored in the memory of the UE (102). The method includes receiving the third NAS message from the first satellite. The method includes storing the third EDT value by replacing the first EDT value with the third EDT value while maintaining the second EDT value associated with the second satellite.

Description

METHOD AND APPARATUS FOR HANDLING ESTIMATED DELIVERY TIME IN STORE AND FORWARD MODE IN A WIRELESS COMMUNICATION SYSTEM

[0001] The present disclosure pertains to the field of a wireless communication system. More particularly, the present disclosure relates to systems and methods for managing estimated delivery times in Store-and-Forward (S&F) mode.

[0002] Considering the development of wireless communication from generation to generation, the technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th generation) communication systems, it is expected that the number of connected devices will exponentially grow. Increasingly, these will be connected to communication networks. Examples of connected things may include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machines, and factory equipment. Mobile devices are expected to evolve in various form-factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond-5G systems.

[0003] 6G communication systems, which are expected to be commercialized around 2030, will have a peak data rate of tera (1,000 giga)-level bit per second (bps) and a radio latency less than 100μsec, and thus will be 50 times as fast as 5G communication systems and have the 1 / 10 radio latency thereof.

[0004] In order to accomplish such a high data rate and an ultra-low latency, it has been considered to implement 6G communication systems in a terahertz (THz) band (for example, 95 gigahertz (GHz) to 3THz bands). It is expected that, due to severer path loss and atmospheric absorption in the terahertz bands than those in mmWave bands introduced in 5G, technologies capable of securing the signal transmission distance (that is, coverage) will become more crucial. It is necessary to develop, as major technologies for securing the coverage, Radio Frequency (RF) elements, antennas, novel waveforms having a better coverage than Orthogonal Frequency Division Multiplexing (OFDM), beamforming and massive Multiple-input Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and multiantenna transmission technologies such as large-scale antennas. In addition, there has been ongoing discussion on new technologies for improving the coverage of terahertz-band signals, such as metamaterial-based lenses and antennas, Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS).

[0005] Moreover, in order to improve the spectral efficiency and the overall network performances, the following technologies have been developed for 6G communication systems: a full-duplex technology for enabling an uplink transmission and a downlink transmission to simultaneously use the same frequency resource at the same time; a network technology for utilizing satellites, High-Altitude Platform Stations (HAPS), and the like in an integrated manner; an improved network structure for supporting mobile base stations and the like and enabling network operation optimization and automation and the like; a dynamic spectrum sharing technology via collision avoidance based on a prediction of spectrum usage; an use of Artificial Intelligence (AI) in wireless communication for improvement of overall network operation by utilizing AI from a designing phase for developing 6G and internalizing end-to-end AI support functions; and a next-generation distributed computing technology for overcoming the limit of UE computing ability through reachable super-high-performance communication and computing resources (such as Mobile Edge Computing (MEC), clouds, and the like) over the network. In addition, through designing new protocols to be used in 6G communication systems, developing mechanisms for implementing a hardware-based security environment and safe use of data, and developing technologies for maintaining privacy, attempts to strengthen the connectivity between devices, optimize the network, promote softwarization of network entities, and increase the openness of wireless communications are continuing.

[0006] It is expected that research and development of 6G communication systems in hyper-connectivity, including person to machine (P2M) as well as machine to machine (M2M), will allow the next hyper-connected experience. Particularly, it is expected that services such as truly immersive eXtended Reality (XR), high-fidelity mobile hologram, and digital replica could be provided through 6G communication systems. In addition, services such as remote surgery for security and reliability enhancement, industrial automation, and emergency response will be provided through the 6G communication system such that the technologies could be applied in various fields such as industry, medical care, automobiles, and home appliances.

[0007] The present disclosure provides method and apparatus for handling estimated delivery times in Store-and-Forward (S&F) mode in wireless communication system.

[0008] According to an aspect of an exemplary embodiment, there is provided method and apparatus for handling estimated delivery times in Store-and-Forward (S&F) mode in wireless communication system.

[0009] Aspects of the present disclosure provide efficient communication methods in a wireless communication system.

[0010] These and other features, aspects, and advantages of the presentinventionare 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 drawings, in which:

[0011] FIG 1A is a schematic diagram that illustrates a normal / default satellite operation mode according to prior art.

[0012] FIG 1B is a schematic diagram that illustrates a S&F Satellite operation mode according to prior art.

[0013] FIG 2 is a schematic representation that illustrates operations performed by the UE when operating in the S&F satellite operation mode according to the prior art.

[0014] FIG 3 illustrates a sequence diagram that illustrates issues related to handling of uplink and downlink S&F estimated delivery time according to prior art.

[0015] FIG 4A is a block diagram of the UE for managing EDT values in the S&F satellite communication network according to embodiments as disclosed herein.

[0016] FIG 4B is a block diagram that illustrates a ground network apparatus for managing EDT values in the S&F satellite communication network according to embodiments disclosed herein.

[0017] FIG 4C is a block diagram that illustrates the satellite for managing EDT values in the S&F satellite communication network according to embodiments as disclosed herein.

[0018] FIG 5A is a flowchart that illustrates a method for managing EDT values in the S&F satellite communication network by UE according to embodiments disclosed herein.

[0019] FIG 5B is a flowchart that illustrates a method for managing EDT values in the S&F satellite communication network by the ground network apparatus according to embodiments disclosed herein.

[0020] FIG 5C is a flowchart that illustrates a method for managing EDT values in the S&F satellite communication network by the satellite according to embodiments disclosed herein.

[0021] FIG 6 is a sequence diagram that illustrates handling of downlink S&F estimated delivery time according to embodiments as disclosed herein.

[0022] FIG. 7 is a block diagram of a terminal or user equipment (UE) according to an embodiment of the disclosure.

[0023] FIG. 8 is a block diagram of a base station (BS) according to an embodiment of the disclosure.

[0024] FIG. 9 is a block diagram of a network entity according to an embodiment of the disclosure.

[0025] This application is based on and derives the benefit of Indian Provisional Applications202541010813filed on9th February 2025, and202541026243filed on21thMarch 2025the contents of which are incorporated herein by reference.

[0026] Recent advancements in satellite communication systems have significantly expanded the availability of wireless connectivity, thereby enabling communication services in remote, rural, and otherwise underserved regions. The integration of satellite access into Fifth Generation (5G) communication networks further extends these advantages by supporting universal service coverage and facilitating the delivery of diverse communication services. Among various satellite operational models supported in such systems, a S&F satellite operation mode is particularly suitable for communication services that are tolerant to transmission delay. In the S&F satellite operation mode, communication services associated with a User Equipment (UE) located within satellite coverage may be maintained even during intermittent or temporary unavailability of satellite connectivity.

[0027] Under a normal or default satellite operation mode in a 5G system, a continuous end-to-end connectivity path is required between the UE, a satellite, and a ground network. Such connectivity requires simultaneous availability of both a service link between the UE and the satellite and a feeder link between the satellite and the ground network, thereby enabling real-time exchange of signaling information and user data. However, this requirement presents substantial challenges in scenarios where continuous connectivity cannot be ensured, such as in systems employing Non-Geostationary Satellite Orbit (NGSO) satellites, which inherently experience periodic service interruptions due to orbital movement.

[0028] The S&F satellite operation mode is designed to address these challenges by decoupling the end-to-end transmission of signaling and data traffic into at least two temporally separated stages. In a first stage, the UE communicates with the satellite while the satellite is not connected to the ground network, wherein uplink signaling and data are stored at the satellite. In a second stage, the satellite subsequently establishes connectivity with the ground network and forwards the stored signaling and data thereto. This operational approach is particularly advantageous for delay-tolerant and non-real-time services, including Internet of Things (IoT) applications for which immediate delivery of data is not required.

[0029] Notwithstanding the foregoing advantages, implementation of the S&F satellite operation mode introduces several technical challenges that adversely impact communication efficiency and reliability. One such challenge relates to the management of an Uplink Store-and-Forward (UL-S&F) estimated delivery time. Although the UE may receive the UL-S&F estimated delivery time via Non-Access Stratum (NAS) signaling messages, such as an attach accept message, a Tracking Area Update (TAU) accept message, or a service accept message, existing specifications do not clearly define the scope, applicability, or validity duration of the received estimated delivery time information. Most importantly the current specifications assume the orbit of all the satellites is same thus the time taken to reach near the ground station will be same, but this does not seems to be correct assumption, satellites are deployed in different orbits thus it may take different time interval for each satellite to reach the ground station depending the orbit(route) it takes, existing features of S&F does not take this into account. As a result, inconsistent interpretation of the UL-S&F estimated delivery time may lead to inefficient resource utilization and unpredictable service behavior.

[0030] In addition, current specifications fail to define any mechanism for estimating a Downlink Store-and-Forward (DL-S&F) delivery time. In the absence of DL-S&F estimated delivery time information, the UE is unable to accurately determine when downlink data or signaling may be delivered. This limitation may result in missed communications, inefficient monitoring behavior, or sub-optimal power consumption. Moreover, without a standardized framework for jointly utilizing both UL-S&F and DL-S&F estimated delivery times, the UE is unable to effectively transition into low-power or idle states during predicted communication unavailability intervals, thereby reducing battery efficiency and overall system performance.

[0031] Thus, it is desired to address the above-mentioned disadvantages, issues, or other shortcomings, or at least provide a useful alternative.

[0032] The principal object of the invention herein is to handle estimated delivery time in the S&F mode.

[0033] Yet another object of the invention is to enable the UE to receive, store, maintain, and update multiple EDT values associated with different satellites in the S&F satellite communication network using satellite identifiers to distinguish and manage the EDT values.

[0034] Yet another object of the invention is to provide a mechanism for generating, encoding, and signaling estimated uplink delivery time duration information along with an associated satellite identifier via NAS messages, thereby enabling accurate estimation of data delivery timelines between the UE and a ground network apparatus.

[0035] In an aspect, the objectives are achieved by providing a method for managing EDT values in a S&F satellite communication network. Further, the method includes receiving by a UE a first NAS message from a first satellite. The first NAS message includes a first EDT value associated with the first satellite. The EDT value represents an estimated time required to deliver data to a ground network apparatus from the time the data is sent by the UE through the serving satellite from which the EDT value is received in the NAS message . Further, the method includes storing by the UE the first EDT value associated with the first satellite in a memory of the UE. Further, the method includes receiving by the UE a second NAS message from a second satellite. The second NAS message comprises a second EDT value associated with the second satellite. Further, the method includes storing by the UE the second EDT value in the memory while maintaining the first EDT value associated with the first satellite stored in the memory of the UE. Further, the method includes receiving by the UE a third NAS message from the first satellite. The third NAS message comprises a third EDT value associated with the first satellite. Further, the method includes storing by the UE the third EDT value by replacing the first EDT value with the third EDT value while maintaining the second EDT value associated with the second satellite.

[0036] In another aspect, the objectives are achieved by a method for managing EDT values in the S&F satellite communication network. Further, the method includes receiving by a ground network apparatus data from a UE. Further, the method includes determining by the ground network apparatus an estimated uplink delivery time duration. The estimated uplink delivery time duration indicates an estimated time required to deliver the data to the ground network element from the time the data is sent by the UE. Further, the method includes encoding by the ground network apparatus the estimated uplink delivery time duration as bytes of a time duration information element. Further, the method includes identifying by the ground network apparatus a satellite ID of a satellite serving the UE. Further, the method includes referencing by the ground network apparatus the satellite ID of the satellite serving the UE for communication with the satellite.

[0037] In yet another aspect, the objectives are achieved by providing a method for managing estimated delivery time information in the S&F satellite communication mode. Furthermore, the method may include determining by a satellite an EDT value for the UE. The EDT value represents an estimated time required to deliver data to a ground network apparatus from the time the data is sent by the UE. Further, the method includes generating by the satellite a NAS message that includes the EDT value and the satellite identifier associated with the satellite. Furthermore, the method may include transmitting by the satellite the NAS message to the UE.

[0038] In yet another aspect, the objectives are achieved by providing the UE for managing EDT values in the S&F satellite communication network. Further, the UE includes a memory, a processor, and an EDT management controller. Further, the EDT management controller may be coupled to the memory and the processor. Further, the EDT management controller receives by the UE a first NAS message from a first satellite. The first NAS message comprises a first EDT value associated with the first satellite. The EDT value represents an estimated time required to deliver data to a ground network apparatus from the time the data is sent by the UE. Further, the EDT management controller stores the first EDT value associated with the first satellite in a memory of the UE. Further, the EDT management controller receives a second NAS message from a second satellite. The second NAS message includes a second EDT value associated with the second satellite. Further, the EDT management controller stores the second EDT value associated with the second satellite in the memory while maintaining the first EDT value value associated with the first satellite stored in the memory of the UE. Further, the EDT management controller receives a third NAS message from the first satellite. The third NAS message includes a third EDT value associated with the first satellite. Further, the EDT management controller stores the third EDT value by replacing the first EDT value with the third EDT value while maintaining the second EDT value associated with the second satellite.

[0039] In yet another aspect, the objectives are achieved by providing a ground network apparatus for managing EDT values in a S&F satellite communication network. Further, a ground network apparatus may include memory, a processor, and an estimated uplink delivery time duration controller. Further, the estimated uplink delivery time duration controller is coupled to the memory and the processor. The estimated uplink delivery time duration controller receives data from the UE. Furthermore, the estimated uplink delivery time duration controller determines an estimated uplink delivery time duration. The estimated uplink delivery time duration indicates an estimated time required to deliver the data to the ground network element from the time the data is sent by the UE. Further, the estimated uplink delivery time duration controller encodes the estimated uplink delivery time duration as bytes of a time duration information element. Furthermore, the estimated uplink delivery time duration controller identifies a satellite ID of a satellite serving the UE. In addition, the estimated uplink delivery time duration controller references the satellite ID of the satellite serving the UE for communication with the satellite.

[0040] In yet another aspect, the objectives are achieved by providing a satellite for managing EDT values in a S&F satellite communication network. Further, the satellite includes a memory, a processor, and an EDT value controller. Further, the EDT value controller is coupled to the memory and the processor. The EDT value controller determines an EDT value for the UE. The EDT value represents an estimated time required to deliver data to a ground network apparatus from the time the data is sent by the UE. Further, the EDT value controller generates a NAS message including the EDT value and the satellite identifier associated with the satellite. Further, the EDT value controller transmits the NAS message to the UE.

[0041] 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 preferred embodiments 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, and the embodiments herein include all such modifications.

[0042] Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

[0043] In describing the embodiments, descriptions related to technical contents well-known in the art and not associated directly with the disclosure will be omitted. Such an omission of unnecessary descriptions is intended to prevent obscuring of the main idea of the disclosure and more clearly transfer the main idea.

[0044] For the same reason, in the accompanying drawings, some elements may be exaggerated, omitted, or schematically illustrated. Further, the size of each element does not completely reflect the actual size. In the drawings, identical or corresponding elements are provided with identical reference numerals or different reference numerals.

[0045] The advantages and features of the disclosure and ways to achieve them will be apparent by making reference to embodiments as described below in detail in conjunction with the accompanying drawings. However, the disclosure is not limited to the embodiments set forth below, but may be implemented in various different forms. The following embodiments are provided only to completely disclose the disclosure and inform those skilled in the art of the scope of the disclosure, and the disclosure is defined only by the scope of the appended claims. Throughout the specification, the same or like reference numerals designate the same or like elements. Furthermore, in describing the disclosure, a detailed description of known functions or constitution incorporated herein will be omitted in the case that it is determined that the description may make the subject matter of the disclosure unnecessarily unclear. The terms which will be described below are terms defined in consideration of the functions in the disclosure, and may be different according to users, intentions of the operators, or customs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

[0046] Herein, it will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, may be performed based on computer program instructions. These computer program instructions may be loaded collectively onto at least one processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which perform through any one of, or in any combination of, the at least one processor of the computer or other programmable data processing apparatus, create means for performing the functions specified in the flowchart block(s). These computer program instructions may also be stored in a non-transitory computer usable or computer-readable memory that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that perform the function specified in the flowchart block(s). The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable data processing apparatus to produce a computer executed process such that the instructions that perform on the computer or other programmable data processing apparatus provide steps for executing the functions specified in the flowchart block(s).

[0047] Further, each block may represent a module, segment, or portion of code, which includes one or more executable instructions for executing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order. For example, two blocks(or functions) shown in succession may in fact be performed substantially concurrently or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved.

[0048] As used in embodiments of the disclosure, a “~unit” may refer to a software element or a hardware element, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), which performs a predetermined function. However, the term including the word “~unit” does not always have a meaning limited to software or hardware. The “~unit” may be constructed either to be stored in an addressable storage medium or to execute one or more processors. Therefore, the “~unit” includes, for example, software elements, object-oriented software elements, components such as class elements and task elements, processes, functions, properties, procedures, sub-routines, segments of a program code, drivers, firmware, micro-codes, circuits, data, database, data structures, tables, arrays, and parameters. The components and functions provided by the “~unit” may be either combined into a smaller number of components and a “~unit,” or divided into additional components and a “~unit.” Moreover, the components and “~units” may be implemented to reproduce one or more central processing units (CPUs) within a device or a security multimedia card. Further, in the embodiments, the “~unit” may include one or more processors.

[0049] It should be appreciated that the blocks in each flowchart and combinations of the flowcharts may be performed by one or more computer programs which include instructions. The entirety of the one or more computer programs may be stored in a single memory device or the one or more computer programs may be divided with different portions stored in different multiple memory devices.

[0050] Any of the functions or operations described herein can be processed by one processor or a combination of processors. The one processor or the combination of processors is circuitry performing processing and includes circuitry like an application processor (AP, e.g. a CPU), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a Wi-Fi chip, a Bluetooth® chip, a global positioning system (GPS) chip, a near field communication (NFC) chip, connectivity chips, a sensor controller, a touch controller, a finger-print sensor controller, a display driver integrated circuit (IC), an audio CODEC chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system on chip (SoC), an IC, or the like.

[0051] It will be appreciated that various embodiments of the disclosure according to the claims and description in the specification can be realized in the form of hardware, software or a combination of hardware and software.

[0052] Any such software may be stored in non-transitory computer readable storage media. The non-transitory computer readable storage media store one or more computer programs (software modules), the one or more computer programs include computer-executable instructions that, when executed by one or more processors of an electronic device individually or collectively, cause the electronic device to perform a method of the disclosure.

[0053] Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like read only memory (ROM), whether erasable or rewritable or not, or in the form of memory such as, for example, random access memory (RAM), memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a compact disk (CD), digital versatile disc (DVD), magnetic disk or magnetic tape or the like. It will be appreciated that the storage devices and storage media are various embodiments of non-transitory machine-readable storage that are suitable for storing a computer program or computer programs comprising instructions that, when executed, implement various embodiments of the disclosure. Accordingly, various embodiments of the present disclosure may provide a program comprising code for implementing apparatus or a method as claimed in any one of the claims of this specification and a non-transitory machine-readable storage storing such a program.

[0054] Hereinafter, the determination of priority between A and B in the present disclosure may refer to various actions such as selecting the one having a higher priority based on a predefined priority rule and performing an operation corresponding thereto, or omitting or dropping an operation corresponding to the one having a lower priority.

[0055] Hereinafter, "A or B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0056] In addition, "at least one of A, B, and C" as described in the present disclosure may be understood to include A, or B, or C, or any combination of A, B, and C.

[0057] In addition, "at least one of A, B, or C" as described in the present disclosure may be understood to include A, or B, or C, or any combination of A, B, and C.

[0058] Furthermore, "A / B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0059] Furthermore, "A, B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0060] Furthermore, "A and B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0061] Furthermore, “if condition A and condition B are satisfied,” as described in the present disclosure, may not be limited to a case where both condition A and condition B are satisfied, but may be understood to include a case where either condition A or condition B is individually satisfied, both condition A and condition B are satisfied, or one or more additional conditions are satisfied in combination.

[0062] Furthermore, throughout this disclosure, ordinal terms such as "first," "second," "third," etc., (and similar qualifiers) are used merely to distinguish between different instances, occurrences, configurations, messages, stages, or aspects of elements, operations, or information as described herein. Unless the context clearly dictates otherwise, the use of such ordinal terms does not itself require that the elements, operations, or information distinguished by these terms be structurally different, numerically distinct, or substantively dissimilar. For example, a "first signal" and a "second signal" may refer to instances of the same signal transmitted at different times or containing the same core information despite minor variations, or they may refer to signals with different content or characteristics, depending on the specific context. Similarly, a "first value" and a "second value" may represent the same magnitude but measured or applied in different circumstances, or they may represent different magnitudes. The interpretation should be guided by the specific technical context, function, and relationship described in the relevant portion of the specification and claims.

[0063] Furthermore, the terms “first ~”, “second ~”, etc., as described in the present disclosure with respect to various elements (e.g., information, objects, operation, sequences, or the like), should not limit those elements. These terms may only be intended to distinguish one element from another, and may not be intended to indicate a specific order. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element.

[0064] Furthermore, even if “first ~” and “second ~” are described in the present disclosure, it may be understood that element(s) referred to by “first ~” and “second ~” may be the same or different. For example, in case of element(s) being information, first information and second information may both be same information and, in some cases, are separate and different information.

[0065] In addition, the terms “if ~” and “in case that ~” as used in the disclosure or claims may be interpreted to include the meanings of “when (or upon) ~,” “in response to ~,” “based on ~,” or “according to ~,” and may be used interchangeably with these expressions. In addition, expressions other than those exemplified herein may also be used, as long as they have substantially the same meaning and do not impair the technical features of the present disclosure.

[0066] For example, the physical layer signaling may be referred to as Layer 1 (L1) signaling and may include downlink control information (DCI). In addition, the higher layer signaling may include a medium access control (MAC) control message, a radio resource control (RRC) signaling message, a non-access stratum (NAS) signaling message, or an application layer message. The RRC signaling message may be referred to as L3 (layer 3) signaling. It should be noted, however, that the higher layer signaling is not limited to the aforementioned examples.

[0067] In addition, the term "not perform" as used in the present disclosure or claims may, in context, be understood to mean that the corresponding step is omitted or skipped. Such a term may be replaced with other terms having the same or substantially equivalent meaning.

[0068] In addition, "transmitting a message including A and B" as described in the present disclosure, may be understood as encompassing both (i) transmitting A and B in a single message, and (ii) transmitting A and B separately via multiple messages (e.g., transmitting a first message including A and a second message including B). This interpretation may also apply to messages that include two or more items (e.g., A, B, C), transmitted either together or separately.

[0069] In addition, "transmitting a message including A and transmitting a message including B" may also be interpreted as transmitting a message including A and B in a single message.

[0070] In the specific embodiments of the present disclosure described below, terms or components included in the disclosure may be expressed in singular or plural form depending on the specific embodiments presented. However, such singular or plural expressions are selected appropriately for convenience of description, and the present disclosure is not limited to a singular or plural number of components. A component expressed in the plural form may be implemented as a single component, and a component expressed in the singular form may be implemented as multiple components.

[0071] The drawings or flowcharts described below illustrate exemplary methods that may be implemented according to the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of the present disclosure. For example, although illustrated as a series of steps, various steps in each drawing or flowchart may overlap, occur in parallel, occur in a different order, or be repeated. In other examples, any step may be omitted or replaced with another step.

[0072] The methods and apparatuses proposed in the embodiments of the present disclosure are not limited to each embodiment individually, but may also be applied in combination of all or some of the embodiments proposed in the disclosure. Therefore, the embodiments of the present disclosure may be modified and applied without significantly departing from the scope of the present disclosure, as would be understood by those skilled in the art.

[0073] In this case, even if certain wordings are described differently across embodiments, they may be used interchangeably or in substitution or in combination if their underlying concepts are equivalent. For example, for the same or equivalent concept, even if one embodiment uses the expression "A" and another embodiment uses the expression "B", such expressions may be understood interchangeably, in substitution, or in combination.

[0074] The terms used in the following description to refer to access nodes, network entities, messages, interfaces between network entities, various types of identification information, and the like, are provided merely for the convenience of explanation by way of example. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may also be used. Such terms may also be interchangeable with terms defined in any 3rd generation partnership project　(3GPP) technical specifications (TS) where appropriate.

[0075] Hereinafter, a base station is an entity that allocates resources to terminals, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a wireless access unit, a BS controller, or a node on a network.

[0076] Furthermore, the base station of the present disclosure may include a split architecture comprising a central unit (CU) and a distributed unit (DU). In this structure, the CU is configured to process the higher layers of the control and user planes, while the DU is configured to process lower-layer radio resource functions. The embodiments of the present disclosure may be equally applicable to 5G base station architectures in which such CU and DU functional splits are implemented.

[0077] A terminal may include a UE, a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions.

[0078] In the disclosure, a downlink (DL) refers to a radio link through which a BS transmits a signal to a UE, and an uplink (UL) refers to a radio link through which a UE transmits a signal to a BS.

[0079] Furthermore, hereinafter, 5th generation (5G) mobile communication technologies (e.g., 5G new radio (NR)), 6th generation (6G) mobile communication technologies may be described by way of example, but the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, newly evolved mobile communication systems developed after 5G and 6G may be included. Furthermore, based on determinations by those skilled in the art, the embodiments of the present disclosure may also be applied to other communication systems (e.g., Wi-Fi systems) through some modifications without significantly departing from the scope of the present disclosure

[0080] In the following description, the terms physical channel and signal may be used interchangeably with data or control signal. For example, the term physical downlink shared channel (PDSCH) refers to a physical channel through which data is transmitted, but the term PDSCH may also be used to refer to the data itself. That is, in the present disclosure, the expression "transmit a physical channel" may be interpreted as being equivalent to the expression "transmit data or a signal via a physical channel."

[0081] Hereinafter, in the context of the present disclosure, higher layer signaling may refer to signaling corresponding to at least one or any combination of the following: master information block (MIB), system information block (SIB) or SIB M (M = 1, 2, ...), radio resource control (RRC), or medium access control (MAC) control element (CE), or a non-access stratum (NAS) signaling message, or an application layer message. The RRC signaling message may be referred to as L3 (layer 3) signaling.

[0082] In addition, L1 signaling may refer to signaling corresponding to at least one or any combination of signaling techniques using the at least one or any combination of the following physical layer channels or signaling: physical downlink control channel (PDCCH), downlink control information (DCI), user equipment (UE)-specific DCI, group-common DCI, common DCI, scheduling DCI (e.g., DCI used for scheduling downlink or uplink data), non-scheduling DCI (e.g., DCI not used for scheduling downlink or uplink data) physical uplink control channel (PUCCH), or uplink control information (UCI). The L1 signaling message may be referred to as a physical layer signaling.

[0083] Hereinafter, the expression that information is configured by the BS, as used in the present disclosure or claims, may, in context, be understood to mean that the terminal receives the corresponding information from the BS via a physical layer signaling or a higher layer signaling. Such an expression may be replaced with other terms having the same or substantially equivalent meaning.

[0084] Hereinafter, the operational principle of the present disclosure will be described in detail with reference to the accompanying drawings.

[0085] 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. Also, the various embodiments described herein are notnecessarilymutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term “or” as used herein, refers to a non-exclusiveor, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples are not be construed as limiting the scope of the embodiments herein.

[0086] As is traditional in the field, embodiments are described and illustrated in terms of blocks that carry out a described function or functions.　These blocks, which 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 optionally be driven by firmware and software. The circuits, 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 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 be physically separated into two or more interacting and discrete blocks without departing from the scope of the proposed method.　Likewise, the blocks of the embodiments be physically combined into more complex blocks without departing from the scope of the proposed method.

[0087] The accompanying drawings facilitate understanding of various technical features. The embodiments are not limited by these drawings and extend to any alterations, equivalents, and substitutes. Terms like first, second, etc., are used for distinction and do not limit the elements.

[0088] Various definitions used in the present invention are as follows. The term Visited Public Land Mobile Network (VPLMN) refers to a Public Land Mobile Network (PLMN) that is different from a Home Public Land Mobile Network (HPLMN) when an Equivalent Home Public Land Mobile Network (EHPLMN) list is not present or is empty, or, when the EHPLMN list is present, a PLMN that is different from any PLMN included in the EHPLMN list. The term “allowable PLMN” refers, in a case of a Mobile Station (MS) operating in MS operation mode A or MS operation mode B, to a PLMN that is not included in a list of forbidden PLMNs stored in the MS, and, in a case of an MS operating in MS operation mode C or an MS not supporting A / Gb mode and not supporting Iu mode, to a PLMN that is not included in the list of forbidden PLMNs and not included in a list of forbidden PLMNs for GPRS service stored in the MS. The term “available PLMN” refers to one or more PLMNs in a given area that are identifiable based on broadcast information from one or more cells (e.g., broadcast system information including PLMN identity information) from which the UE can attempt to obtain wireless communication service.

[0089] The term “camped on a cell” refers to a state in which the MS, or Mobile Equipment (ME) when no Subscriber Identity Module (SIM) is present, has completed a cell selection or reselection process and has selected a cell from which the MS or ME intends to receive available services. The available services may be limited, and the PLMN or a Standalone Non-Public Network (SNPN) may not be aware of the existence of the MS or ME within the selected cell. The term Equivalent Home Public Land Mobile Network (EHPLMN) refers to any PLMN entry contained in an Equivalent Home Public Land Mobile Network list. The term “Equivalent Home Public Land Mobile Network list” refers to a list of PLMN codes stored on a Universal Subscriber Identification Module (USIM), the PLMN codes in the list being configured to replace an HPLMN code derived from an International Mobile Subscriber Identity (IMSI) for PLMN selection purposes. The Equivalent HPLMN list may include the HPLMN code derived from the IMSI. When the HPLMN code derived from the IMSI is not included in the Equivalent HPLMN list, the HPLMN code derived from the IMSI is treated as a VPLMN for PLMN selection purposes. The term “Home Public Land Mobile Network (HPLMN)” refers to a PLMN for which a Mobile Country Code (MCC) and a Mobile Network Code (MNC) of a PLMN identity match the MCC and MNC of the IMSI.

[0090] The term Registered Public Land Mobile Network (RPLMN) refers to the PLMN on which one or more location registration outcomes, also referred to as registration procedure outcomes, have occurred. In a shared network, the Registered PLMN is defined by a PLMN identity of a core network (CN) operator that has accepted the location registration. The term “registration” refers to a process of camping on the cell of the PLMN or an SNPN and performing one or more required location registration procedures and / or NAS registration signaling as applicable. The term User Controlled Public Land Mobile Network (UPLMN) refers to the PLMN and access technology combination listed, in priority order, in a User Controlled PLMN Selector with Access Technology data file stored in the SIM. The term Operator Controlled Public Land Mobile Network (OPLMN) refers to the PLMN and access technology combination listed, in priority order, in an Operator Controlled PLMN Selector with Access Technology data file stored in the SIM, or stored, in priority order, in the ME.

[0091] The term “serving satellite” refers to the satellite that provides satellite access to the UE. In a case of a Non-Geostationary Orbit (NGSO) satellite system, the serving satellite changes over time due to the nature of a satellite constellation. The term “S&F Satellite operation” refers to an operation mode of a 5G system with satellite access in which the 5G system is configured to provide a level of service by storing and forwarding data when satellite connectivity to a ground segment is intermittently or temporarily unavailable, for example, to provide communication service to UEs under satellite coverage without a simultaneous active feeder link connection to a ground segment. The term “S&F data retention period” refers to a data storage validity period for the 5G system with satellite access supporting S&F operation, after which undelivered stored data is discarded. The term UE-Satellite-UE Communication refers to communication, in a 5G system with satellite access, between UEs under coverage of one or more serving satellites using satellite access without routing through a ground segment. The term “S&F mode” refers to a mode in which the UE, radio access network (RAN), and core network entities perform S&F Satellite operation.

[0092] The NAS messages described herein may include, but are not limited to, Registration Request, Deregistration Request, Service Request, 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, and UE Parameters Update.

[0093] As used herein, the term Radio Access Technology (RAT) refers to one of: Next Generation Radio Access Network (NG-RAN), 5G, 4G, 3G, 2G, Evolved Packet System (EPS), 5G System (5GS), New Radio (NR), NR in unlicensed bands, NR with Low Earth Orbit (LEO) satellite access, NR with Medium Earth Orbit (MEO) satellite access, NR with Geostationary Earth Orbit (GEO) satellite access, NR with other satellite (OTHERSAT) access, NR RedCap, Evolved Universal Terrestrial Radio Access (E-UTRA), E-UTRA in unlicensed bands, Narrowband Internet of Things (NB-IoT), Wideband Internet of Things (WB-IoT), and LTE-M. The term “5GS registration type” refers to a registration type in the 5GS, which can be one of: an initial registration, a mobility registration updating, a periodic registration updating, an emergency registration, SNPN onboarding registration, a disaster roaming initial registration, or a disaster roaming mobility registration updating. Setting a 5GS registration type to a value other than disaster roaming initial registration or disaster roaming mobility registration updating means that the 5GS registration type is set to at least one of initial registration, mobility registration updating, periodic registration updating, emergency registration, or SNPN onboarding registration.

[0094] In an embodiment, PLMN selection without RPLMN, as per 3GPP TS 23.122, includes the MS selecting and attempting registration on available and allowable PLMN / access technology combinations by first selecting either the HPLMN (if the EHPLMN list is not present or is empty) or the highest-priority available EHPLMN (if the EHPLMN list is present), followed by selecting each PLMN / access technology combination in the User Controlled PLMN Selector with Access Technology data file in the SIM in priority order, followed by each PLMN / access technology combination in the Operator Controlled PLMN Selector with Access Technology data file in the SIM or stored in the ME in priority order, and thereafter selecting other PLMN / access technology combinations based on received signal quality.

[0095] In an embodiment, PLMN selection with RPLMN, as per 3GPP TS 23.122, includes the MS selecting and attempting registration on available and allowable PLMN / access technology combinations by first selecting the RPLMN or last registered PLMN, followed by either the HPLMN (if the EHPLMN list is not present or is empty) or the highest-priority available EHPLMN (if the EHPLMN list is present), followed by selecting each PLMN / access technology combination in the User Controlled PLMN Selector with Access Technology data file in the SIM in priority order, followed by each PLMN / access technology combination in the Operator Controlled PLMN Selector with Access Technology data file in the SIM or stored in the ME in priority order, and thereafter selecting other PLMN / access technology combinations based on received signal quality.

[0096] For a 5G system with satellite access, service continuity may be supported between NR terrestrial access networks and NR satellite access networks, whether owned by the same operator or by different operators having an agreement. The NTN and TN may operate in different frequency bands (e.g., FR1 versus FR2) or in the same frequency band. The terms Satellite 3GPP access, Satellite access, Satellite Access Network, NR Satellite Access Network, Satellite NG-RAN Access Technology, and NR Satellite access are used interchangeably. The embodiments explain methods, issues, and solutions using NR satellite access or Satellite NG-RAN Access Technology as examples, without limiting the disclosure to NR satellite access, and the principles described herein may be applied, where applicable, to Satellite E-UTRAN Access Technology in NB-S1 mode or WB-S1 mode and to NB-IoT or WB-IoT satellite access or architecture.

[0097] Unless expressly limited, solutions described using NR and a 5G core (5GC) are also applicable to legacy RATs such as E-UTRA / LTE by replacing corresponding core network entities (for example, replacing AMF with MME, gNB with eNB, and UDM with HSS), and solutions described using LTE / EPC are similarly applicable to 5G / 5GC, with the underlying principles remaining the same. The network used in the embodiments is described using a 5G core network function (e.g., AMF) as an example; however, the network may include any 5G or E-UTRAN core network entities (e.g., AMF, SMF, MME, UPF) and any 5G or E-UTRAN RAN entities (e.g., eNB, gNB, NG-RAN). The messages illustrated in the embodiments are examples and may include other signaling messages exchanged between the UE and network entities or between different network entities.

[0098] As used herein, the terms wait timer, DisCo wait timer, Discontinuous Coverage wait timer, Random timer, Random wait timer, and DCW timer are used interchangeably, and the terms wait range, DisCo wait range, Discontinuous Coverage wait range, and DCW range are used interchangeably. As used herein, an “area” may refer to a cell or cell ID, a Tracking Area Code (TAC) or Tracking Area Identity (TAI), a PLMN, an MCC or MNC, latitude / longitude coordinates, a Closed Access Group (CAG) cell, or any other geographical location or coordinate.

[0099] For non-limiting reference, lists of NAS messages may be found in 3GPP TS 24.501 and 3GPP TS 24.301, and lists of access stratum (AS) messages may be found in 3GPP TS 38.331 and 3GPP TS 36.331. The NAS and AS messages described in the embodiments are provided for illustration only and may include any NAS or AS messages as defined by the applicable protocol between the UE and AMF / MME and between the UE and gNB / eNB. Further, as used herein, the term “satellite” may represent any satellite, constellation of satellites, or aerial body in any satellite orbit, including Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geostationary Orbit (GEO), or High Earth Orbit (HEO), and may represent any RAN entity, core network entity, or network function associated with satellite access.

[0100] FIG. 1A is a schematic diagram that illustrates a normal / default satellite operation mode according to prior art. The normal / default satellite operation mode is depicted in FIG. 1A, where the S&F satellite operation in a 5G system with satellite access is configured to provide communication service to UEs (102) under satellite coverage. This configuration supports delay-tolerant communication even when satellite connectivity is intermittent or temporarily unavailable, such as when the satellite (101) is not connected to the external network or IoT service endpoint (104) via a feeder link or inter-satellite link.

[0101] In the normal / default satellite operation mode, as illustrated in FIG. 1A, the UE (102) communicates with the satellite (101) over a service link while the satellite (101) maintains simultaneous connectivity with the ground network (103) via a feeder link. In this mode, signaling and data traffic exchanged between the UE (102) and the network occur in real-time, ensuring a continuous end-to-end connectivity path between the UE (102), the satellite (101), and the ground network (103). Both the service link and the feeder link are active concurrently, with no storage or delay-tolerant handling of data performed. Communication is only possible when the satellite (101) is connected to both the UE (102) and the external network / IoT service endpoint (104), ensuring uninterrupted end-to-end data exchange.

[0102] FIG. 1B is a schematic diagram that illustrates a Store & Forward (S&F) satellite operation mode according to prior art. Under the S&F satellite operation mode, as illustrated in FIG. 1B, the end-to-end exchange of signaling and data traffic is performed in a combination of two steps that are not concurrent in time (step A (101a) and step B (101b) in FIG. 1B). In step A, signaling and / or data exchange between the UE (102) and the satellite (101) occurs without the satellite (101) being simultaneously connected to the ground network (103), meaning the satellite (101) operates the service link without an active feeder link connection. In step B, connectivity between the satellite (101) and the ground network (103) is established to enable the satellite to forward the stored signaling and / or data to the ground network. Consequently, the satellite transitions from being connected to the UE (102) in step A to being connected to the ground network in step B.

[0103] The concept of S&F service is widely used in delay-tolerant networking and disruption-tolerant networking. In a 3GPP context, a service equivalent to the S&F service is SMS, where end-to-end connectivity between end-points is not required; instead, connectivity is only required between each end-point and the SMSC, which stores and relays the messages. The support of S&F satellite operation is particularly suitable for delivering delay-tolerant and non-real-time IoT satellite services using NGSO satellites.

[0104] The MME functionality is split into two parts: MME-onboard, which is the MME part onboard the satellite, and MME-ground. When the UE (102) initiates an Attach or TAU procedure, it indicates support for S&F mode to the MME in accordance with existing NAS capability. If the procedure cannot be completed due to S&F operation, the MME sends an Attach or TAU Reject message to the UE (102). This message includes: a) information indicating that the attach or TAU procedure cannot be completed due to S&F operation and that the UE (102) may re-attempt the attach or TAU in this PLMN in the next satellite pass, thereby indicating that the information contained in the Attach or TAU Request message is stored by the MME and the network will be available after interaction with the ground network; b) a wait timer indicating the time the UE (102) should wait before re-attempting the Attach or TAU procedure in the current or another satellite of the same PLMN; and c) optionally, a list of Satellite IDs over which the UE (102) may re-attempt the Attach or TAU procedure after the wait timer expires, wherein the Satellite IDs are based on SIB information broadcasted by the eNB.

[0105] During the wait timer, the UE (102) may search for another terrestrial or satellite PLMN to obtain normal service. If the UE (102) receives a non-integrity protected reject message from the network and is not configured to use T3245, the UE (102) shall start a timer T3247 with a value randomly drawn between 30 minutes to 40 minutes and maintain a counter for SIM / USIM considered invalid for non-GPRS services or SIM / USIM considered invalid for GPRS services with an MS implementation-specific maximum value.

[0106] Further, upon expiry of timer T3247, the MS shall:

[0107] - erase the list of "forbidden location areas for regional provision of service" and the list of "forbidden location areas for roaming";

[0108] - set the SIM / USIM to valid for non-GPRS services, if

[0109] - the MS does not maintain a counter for "SIM / USIM considered invalid for non-GPRS services" events; or

[0110] - the MS maintains a counter for "SIM / USIM considered invalid for non-GPRS services" events and this counter has a value less than an MS implementation-specific maximum value.

[0111] - set the SIM / USIM to valid for GPRS services, if

[0112] - the MS does not maintain a counter for "SIM / USIM considered invalid for GPRS services" events; or

[0113] - the MS maintains a counter for "SIM / USIM considered invalid for GPRS services" events and this counter has a value less than an MS implementation-specific maximum value.

[0114] - erase the list of "forbidden location areas for non-GPRS services" and the list of "forbidden location areas for GPRS services", if the MS maintains these lists;

[0115] - if the MS maintains a list of PLMN-specific attempt counters, for each PLMN-specific attempt counter that has a value greater than zero and less than an MS implementation-specific maximum value, remove the respective PLMN from the extension of the "forbidden PLMNs" list; and

[0116] - if the MS maintains a list of PLMN-specific PS-attempt counters, for each PLMN-specific PS-attempt counter that has a value greater than zero and less than an MS implementation-specific maximum value, remove the respective PLMN from the "forbidden PLMNs for GPRS service" list. If the resulting "forbidden PLMNs for GPRS service" list is empty and the MS is supporting S1 mode, the MS re-enables the E-UTRA capability as specified in 3GPP TS 24.301

[0120] for the case when timer T3247 expires.

[0117] FIG. 2 is a schematic representation illustrating operations performed by the UE (102) when operating in the S&F satellite operation mode according to the prior art. Signaling and data exchanges between the satellite (101) at different locations, the UE (102), and the ground network apparatus (103) during execution of the S&F operation mode are disclosed in FIG. 2.

[0118] In an embodiment, within a Non-Geostationary Satellite Orbit (NGSO) system, the UE (102) may be served by different satellites at different times. For instance, the UE (102) may initially be served by a first satellite having a first satellite ID, then move to coverage of a second satellite having a second satellite ID, and later return to coverage of the first satellite. Each satellite provides its own EDT value associated with its satellite ID.

[0119] The sequence diagram illustrates signaling and data exchanges between the satellite (101), the UE (102), and the ground network (103) during execution of the S&F operation mode. As depicted in FIG. 2, the satellite (101) may be at a first satellite location (201) where the feeder link is unavailable or at a second satellite location (202) where the feeder link is available. Core network functionality and radio access functionality are deployed onboard the satellite (101). The UE (102) communicates with the satellite (101) using access and mobility management procedures corresponding to the selected PLMN. The satellite (101) obtains location information associated with the UE (102) and verifies whether the UE (102) is authorized to access the selected PLMN. In certain scenarios, such as prior to a loss of satellite coverage, the satellite (101) initiates a detach procedure for the UE (102).

[0120] In the existing architecture illustrated in FIG. 2, core network functionality and radio access functionality are assumed to be deployed onboard the satellite (101). Consequently, the UE (102) communicates with the satellite (101) using access and mobility management procedures corresponding to a selected PLMN. The satellite (101) may obtain location information associated with the UE (102) and may verify whether the UE (102) is authorized to access the selected PLMN. In certain situations, such as prior to a loss of satellite coverage, the satellite (101) may initiate a detach procedure for the UE (102).

[0121] Further, after the UE (102) loses coverage when the satellite (101) is at the first satellite location (201) and subsequently moves to the second satellite location (202) and establishes a feeder link with the ground network apparatus (103) corresponding to the PLMN selected by the UE (102), the satellite (101) or an onboard endpoint proxy (204, 205) transfers UE-related information and stored data to an S&F function (206) associated with the ground network apparatus (103). The endpoint proxy (204) handles mobile-originated (MO) data and mobile-terminated (MT) data when the satellite (101) is at the first satellite location (201), and the endpoint proxy (205) handles MO data and MT data when the satellite (101) is at the second satellite location (202). The transferred information includes at least one of an International Mobile Subscriber Identity (IMSI), last known location information of the UE (102), and stored signaling and user data corresponding to mobile-originated (MO) transactions. The S&F function (206) acts as a proxy for MO data and MT data communication with one or more remote endpoints (207).

[0122]

[0123] TABLE-1

[0124] In an embodiment, user location information associated with the UE (102) is illustrated in Table 1. As described in 3GPP Technical Specification (TS) 36314, User Location Information (ULI) of the UE (102) is provided by a Radio Access Network node to a mobility management entity as part of an S1 Application Protocol (S1AP) message. In an embodiment, mobility management functionality is split between an onboard mobility management entity deployed on the satellite (101) and a ground-based mobility management entity deployed in the ground network apparatus (103). When the UE (102) initiates an attach procedure or a TAU procedure, the UE (102) indicates support for the S&F operation mode using NAS capability signaling. If completion of the attach procedure or the TAU procedure is not feasible due to S&F operation, a reject message is transmitted to the UE (102).

[0125] Further, the reject message may include information indicating to the UE (102) that an attach procedure or the TAU procedure cannot be completed due to operation in the S&F mode and that the UE (102) may re-attempt the attach procedure or the TAU procedure with the same PLMN during a subsequent satellite pass of a satellite (101), thereby indicating that information contained in a corresponding request message is stored and that network access may become available following interaction between the satellite (101) and a ground network (103). The reject message may further include a wait timer value indicating a duration for which the UE (102) is to wait before re-attempting the attach procedure or the TAU procedure via the satellite (101) or via another satellite associated with the same PLMN.

[0126] Further, the reject message includes information indicating to the UE (102) that an attach procedure or the TAU procedure cannot be completed due to operation in the S&F mode and that the UE (102) may re-attempt the attach procedure or the TAU procedure with the same PLMN during a subsequent satellite pass of the satellite (101), thereby indicating that information contained in a corresponding request message is stored and that network access may become available following interaction between the satellite (101) and the ground network apparatus (103). The reject message further includes a wait timer value indicating a duration for which the UE (102) is to wait before re-attempting the attach procedure or the TAU procedure via the satellite (101) or via another satellite associated with the same PLMN.

[0127] Further, the mobility management entity indicates to the UE (102) an UL-S&F estimated delivery time in one or more NAS accept messages. The NAS accept messages include at least one of attach accept message, a TAU accept message, or a service accept message. The UL-S&F estimated delivery time represents an estimated time duration required to deliver uplink data from the UE (102) to the ground network apparatus (103) measured from a time at which the uplink data is transmitted by the UE (102).

[0128] FIG. 3 illustrates a sequence diagram that highlights issues related to the handling of uplink and downlink S&F estimated delivery times according to prior art. In the S&F mode of operation, when the UE (102) transmits uplink data to the ground network apparatus (103), the data from the UE (102) is stored on the satellite (101), which has an onboard mobility management entity (MME), until a feeder link to the ground network apparatus (103) becomes available. An UL-EDT enables the UE (102) to determine when the uplink data might be delivered to the ground network apparatus (103).

[0129] In the prior art, the uplink S&F estimated delivery time is received by the UE (102) in an attach accept message, a TAU accept message, or a service accept message. However, the scope and validity of the uplink S&F estimated delivery time information element (IE) are not clearly defined. Further, the duration for which the uplink S&F estimated delivery time information should be stored by the UE (102) is not specified.

[0130] For downlink transmission, the ground network apparatus (103) transmits data to the UE (102) via the satellite (101). When the satellite (101) operates in S&F mode, the downlink data is stored on the satellite (101) until a service link to the UE (102) becomes available. Current specifications in prior art do not provide any downlink S&F estimated delivery time. Consequently, the UE (102) cannot accurately anticipate when to expect incoming data from the ground network apparatus (103). A standardized approach for utilizing estimated delivery time is required for both uplink and downlink transmission in the S&F mode of operation. With bidirectional EDT including UL-EDT and DL-EDT, the UE (102) can enter low-power states during predicted downtime periods, thereby extending the battery life of the UE (102).

[0131] At step S1, the UE (102) initiates the NAS procedure including at least one of an initial attach procedure, a TAU procedure, or a service request procedure, and transmits an attach request message, a tracking area update request message, a service request message, an Evolved Packet System (EPS) Session Management (ESM) data transport message, or any other NAS message to the onboard MME on the satellite (101) via an available service link. The UE (102) includes S&F capability information in the transmitted NAS message.

[0132] At step S2, in the absence of a feeder link between the satellite (101) and the ground network apparatus (103), the onboard MME on the satellite (101) cannot forward the NAS signaling message from the UE (102) to a ground-based MME on the ground network apparatus (103). The onboard MME on the satellite (101) determines and includes an uplink estimated S&F delivery time IE in a downlink NAS message transmitted to the UE (102), wherein the downlink NAS message includes at least one of the attach accept message, a tracking area update accept message, or a service accept message.

[0133] At steps 3A and 3B, according to current specifications in prior art, no method is defined to handle the uplink S&F estimated delivery time, and the ground network apparatus (103) does not provide any downlink S&F estimated delivery time. In the prior art, the uplink S&F estimated delivery time is received by the UE (102) in the attach accept message, the TAU accept message, or the service accept message, but no method is defined to handle the scope and validity of the uplink S&F estimated delivery time or the downlink S&F estimated delivery time.

[0134] For downlink transmission, the ground network apparatus (103) transmits data to the UE (102) via the satellite (101). When the satellite (101) operates in S&F mode, the downlink data is stored on the satellite (101) until a service link to the UE (102) becomes available. However, current specifications in prior art do not provide any downlink S&F estimated delivery time to the UE (102).

[0135] To overcome the disadvantages of the prior art, there is a need for handling estimated delivery time in S&F mode. The present invention addresses the scope and validity of uplink and downlink S&F estimated delivery time, managing multiple estimated delivery time values on a per-satellite basis, and defining storage duration for the estimated delivery time information at the UE (102).

[0136] FIG. 4A is a block diagram of the UE (102) for managing EDT values in an S&F satellite communication network, according to embodiments as disclosed herein. Examples of the UE (102) include, but are not limited to, mobile phones, smartphones, tablets, wearable devices, televisions, computing devices, IoT devices, automotive systems (including V2X devices), enterprise devices (including robotics), specialized equipment (including medical and public safety devices), and media devices (including gaming and streaming devices).

[0137] Examples of the wireless communication network system include, but are not limited to, cellular networks (such as 2G, 3G, 4G, 5G, and beyond-5G / 6G) and non-terrestrial networks (NTN) including satellite access networks supporting S&F operation. In the context of the present disclosure, the S&F satellite communication network refers to a satellite-access system in which data and / or control signaling may be buffered and forwarded when a feeder link to a ground segment is intermittently unavailable.

[0138] The UE (102) includes a processor (401), a memory (403), an I / O interface (402), and an EDT management controller (404). The processor (401) is operatively coupled to the memory (403), the I / O interface (402), and the EDT management controller (404) and is configured to execute instructions for UE operations.

[0139] The memory (403) stores EDT-related information including one or more EDT values associated with respective satellite identifiers and / or network contexts, and may further store validity information that defines applicability of an EDT value, including association with a TAI list, registration area, PLMN, and / or serving satellite context. The memory (403) may also store other UE context information required for operation in S&F mode.

[0140] The I / O interface (402) provides communication between internal components of the UE (102) and one or more external entities, and in one embodiment includes an interface to radio / modem circuitry configured to exchange control-plane signaling, including NAS messages carrying EDT information, via satellite access.

[0141] In an embodiment, the EDT management controller (404) is coupled to the memory (403) and the processor (401). This coupling allows for efficient data transfer and communication between the components, ensuring that the EDT management controller (404) accesses and processes EDT data in real time. The EDT management controller (404) is an innovative integrated circuit that is implemented in the UE (102). In an embodiment, the structure of such innovative integrated circuit includes a microcontroller-based hardware circuit that enables dynamic management and processing of EDT values for S&F operations in a non-terrestrial network. The EDT management controller (404) is configured to receive, via NAS signaling, EDT information and an associated satellite identifier (and / or an associated scope such as a TAI list or registration area), to store a plurality of EDT values associated with respective satellite identifiers, to select an EDT value based on the satellite identifier of a serving satellite, and to maintain multiple EDT values simultaneously for different satellites. The EDT management controller (404) is further configured to replace an EDT value when a new EDT value is received from the same satellite while maintaining EDT values associated with other satellites, and to provide the stored EDT value(s) to upper layers and / or an application interface (including via AT command reporting where supported). The EDT management controller (404) is further configured to delete or invalidate one or more stored EDT values upon detecting at least one of: deregistration, USIM change, expiry of an EDT validity condition, change of registration area / TAI scope, or a satellite change event that renders a stored EDT value not applicable. In this manner, the EDT management controller (404) provides hardware-assisted, per-satellite management of EDT information in S&F operation while maintaining consistency of EDT applicability across mobility and connectivity changes.

[0142] Further, the EDT management controller (404) receives the first Non-Access Stratum (NAS) message from the first satellite. The first NAS message includes a first EDT value associated with the first satellite. The EDT value represents the estimated time required to deliver data to the ground network apparatus (103) from the time the data is sent by the UE (102). Further, the EDT management controller (404) stores the first EDT value associated with the first satellite (101) in a memory of the UE (102). Further, the EDT management controller (404) receives the second NAS message from the second satellite. The second NAS message includes the second EDT value associated with the second satellite. Further, the EDT management controller (404) stores the second EDT value associated with the second satellite in the memory while maintaining the first EDT value associated with the first satellite stored in the memory of the UE (102). Further, the EDT management controller (404) receives a third NAS message from the first satellite. The third NAS message includes the third EDT value associated with the first satellite. Further, the EDT management controller (404) stores the third EDT value by replacing the first EDT value with the third EDT value while maintaining the second EDT value associated with the second satellite.

[0143] Further, the EDT management controller (404) transmits each of the stored EDT values associated with the satellite ID and the associated satellite ID stored in the memory of the UE (102) from a NAS layer of the UE (102) to one or more upper layers of the UE (102). The UE (102) transmits each of the stored EDT values using an AT command to inform the upper layers that the UE (102) is in an S&F mode of operation. Further, the EDT management controller (404) determines the time required to send or receive the data to the ground network apparatus (103) through the serving satellite from which the EDT value is received in the NAS message through the serving satellite from which the EDT value is received in the NAS message. Further, the UE determines the satellite from the satellite ID information broadcasted by the eNB. In addition, the ground station or the target application server or node is identified by at least one of a Public Land Mobile Network (PLMN) and a satellite (101) ID.

[0144] Further, the UE (102) in the EDT management controller (404) replaces the first EDT value with the third EDT value by deleting the first EDT value from the memory of the UE (102) and adding the third EDT value without impacting the stored EDT-2 associated with the second satellite. Further, each of the EDT values is included in a S&F satellite (101) operation parameters IE of the corresponding NAS message.

[0145] Further, the NAS message is a registration accept message or a tracking area update accept message. Further, the EDT timer value is valid within at least one of a TAI list, registration area, area cell, or cell list, wherein the cell list includes cells belonging to the same satellite (101) identifier in which the EDT value is received. Furthermore, each of the EDT values is stored in the memory of the UE (102) per satellite (101) using the satellite (101) identifier corresponding to the satellite (101) from where the EDT value is received. Further, the EDT management controller (404) determines an expected time for receiving an acknowledgment corresponding to data transmitted via the satellite (101) identified by the associated satellite (101) identifier. Further, the EDT management controller (404) deletes all stored EDT values in response to the UE (102) transitioning to a deregistered state.

[0146] Further, the UE (102) determines the satellite from the satellite ID information broadcasted by the eNB.

[0147] In an embodiment, the UE (102) operating in S&F satellite communication mode is configured to manage EDT values on a per-satellite basis. When the UE (102) receives a first estimated delivery time value from a first satellite identified by a first satellite identifier, the UE (102) stores the first estimated delivery time value in a memory (403) of the UE (102) in association with the first satellite identifier. Further, when the UE (102) receives a second estimated delivery time value from a second satellite identified by a second satellite identifier, the UE (102) stores the second estimated delivery time value in the memory (403) while maintaining the previously stored first estimated delivery time value such that multiple estimated delivery time values corresponding to different satellite identifiers are concurrently maintained by the UE (102).

[0148] In an embodiment, when the UE (102) subsequently receives an updated estimated delivery time value from the same first satellite identified by the first satellite identifier (SAT-1), the UE (102) deletes the previously stored estimated delivery time value associated with the first satellite identifier and stores the updated estimated delivery time value in association with the first satellite identifier. The deletion or replacement of the estimated delivery time value associated with the first satellite identifier does not impact the estimated delivery time value associated with the second satellite identifier.

[0149] In an embodiment, the NAS layer of the UE (102) provides the estimated delivery time value together with the associated satellite identifier to one or more upper layers of the UE (102). The one or more upper layers utilize the estimated delivery time value to determine the estimated time required to deliver data to a ground network apparatus (103) from the time at which the data is transmitted by the UE (102) and to control at least one of data transmission timing, power consumption behavior, or service handling of the UE (102) during S&F satellite operation.

[0150] FIG. 4B is a block diagram that illustrates a ground network apparatus (103) for managing EDT values in an S&F satellite (101) communication network, according to embodiments disclosed herein.

[0151] Examples of the ground network apparatus (103) include, but are not limited to, core network nodes and / or network functions (e.g., MME / AMF, SMF, UPF, HSS / UDM), satellite gateway systems, feeder link controllers, ground station equipment, S&F function servers, network management systems, edge computing servers, and data centers connected to satellite communication infrastructure.

[0152] The ground network apparatus (103) includes a processor (405), a memory (407), an I / O interface (406), and an estimated uplink delivery time duration controller (408). The processor (405) of the ground network apparatus (103) communicates with the memory (407), the I / O interface (406), and the estimated uplink delivery time duration controller (408), and is configured to execute instructions to perform ground-segment operations for S&F satellite communication.

[0153] The memory (407) stores information usable for EDT processing, including at least per-satellite and / or per-UE parameters, and may further store configuration data for encoding and / or signaling EDT-related information in control-plane messages.

[0154] The I / O interface (406) provides communication between internal components of the ground network apparatus (103) and one or more external entities. In one embodiment, the I / O interface (406) includes one or more network interface controllers and protocol interface modules configured to exchange signaling and data with a satellite gateway and / or a satellite (101), and to exchange NAS-related information with core network entities.

[0155] In an embodiment, the estimated uplink delivery time duration controller (408) is coupled to the memory (407) and the processor (405). This coupling allows for efficient data transfer and communication between the components, ensuring that the estimated uplink delivery time duration controller (408) accesses and processes estimated uplink delivery time duration data in real time. The estimated uplink delivery time duration controller (408) is an innovative integrated circuit that is implemented in the ground network apparatus (103). In an embodiment, the structure of such innovative integrated circuit includes a microcontroller-based hardware circuit that enables dynamic determination and processing of estimated uplink delivery time duration for S&F operations in a non-terrestrial network. The estimated uplink delivery time duration controller (408) is configured to receive data and / or uplink delivery status information associated with the UE (102), determine an estimated uplink delivery time duration indicating an estimated time required to deliver the data to a ground network element from a time the data is sent by the UE (102), associate the estimated uplink delivery time duration with a satellite identifier of the satellite (101) serving the UE (102) and, where applicable, with a UE identifier and / or scope information, encode the estimated uplink delivery time duration in a standardized format as three bytes including octets 3 to 5 of a Time Duration information element, and transmit the encoded estimated uplink delivery time duration towards the satellite gateway and / or the satellite (101) for inclusion in downlink NAS messages to the UE (102). The estimated uplink delivery time duration controller (408) is further configured to update the estimated uplink delivery time duration responsive to changing feeder link availability, satellite scheduling, and / or ground segment loading conditions, thereby enabling delivery-time indication that reflects S&F behavior. Any references to “analog components” are optional and non-limiting; in one embodiment the controller (408) is implemented predominantly using digital circuitry including a microcontroller (MCU) and associated timer / counter circuitry for duration computation and message-format encoding.

[0156] Further, the estimated uplink delivery time duration controller (408) receives data from the UE (102). Further, the estimated uplink delivery time duration controller (408) determines an estimated uplink delivery time duration. The estimated uplink delivery time duration indicates an estimated time required to deliver the data to the ground network element from the time the data is sent by the UE (102). Further, the estimated uplink delivery time duration controller (408) encodes the estimated uplink delivery time duration as bytes of a Time duration information element. Further, the estimated uplink delivery time duration controller (408) identifies the satellite ID of the satellite (101) serving the UE (102). Further, the estimated uplink delivery time duration controller (408) references the satellite ID of the satellite (101) serving the UE (102) for communication with the satellite.

[0157] Further, the estimated uplink delivery time duration controller (408) receives the satellite identifier. The satellite identifier is of an integer type and indicates the identifier of the serving satellite (101) that provides an estimated uplink delivery time duration. Further, the estimated uplink delivery time duration is encoded by the estimated uplink delivery time duration controller (408) as three bytes corresponding to octets 3 to 5 of a Time Duration information element.

[0158] FIG. 4C is a block diagram that illustrates the satellite (101) for managing EDT values in an S&F satellite communication network, according to embodiments as disclosed herein. Examples of the satellite (101) include, but are not limited to, Low Earth Orbit (LEO) satellites, Medium Earth Orbit (MEO) satellites, Geostationary Earth Orbit (GEO) satellites, and non-geostationary orbit (NGSO) satellites configured to support S&F communication. The satellite (101) may include satellite payload equipment such as onboard radio access network components (e.g., satellite-based eNB or gNB), onboard processing units, satellite communication transceivers, feeder link interfaces, service link interfaces, onboard memory units for temporary data storage, routing and forwarding modules, protocol handling modules, and satellite control and management subsystems. The satellite (101) may further include onboard network functionality, including S&F buffering and forwarding functions, NAS message relay and / or generation functions, EDT value determination and / or handling functions, timing and scheduling functions, and satellite identifier handling functions, for supporting delay-tolerant communication services in an S&F satellite communication network.

[0159] The satellite (101) includes the processor (409), the memory (411), an I / O interface (410), and an EDT value controller (412). The processor (409) of the satellite (101) communicates with the memory (411), the I / O interface (410), and the EDT value controller (412). The processor (409) is configured to execute instructions stored in the memory (411) and to perform satellite payload processing for S&F operation.

[0160] The memory (411) stores uplink and downlink data, signaling information, EDT values, satellite identifier information, and buffering data required for S&F communication between the UE (102) and the ground network apparatus (103), including temporary storage of undelivered data and / or control information during feeder-link unavailability.

[0161] The I / O interface (410) provides communication between internal components of the satellite (101) and external entities. In one embodiment, the I / O interface (410) includes one or more transceiver interfaces and protocol interface modules for service links to UEs and feeder links to the ground segment, and is configured to exchange signaling and data relevant to EDT transmission and S&F operation.

[0162] Further, the EDT value controller (412) is coupled to the memory (411) and the processor (409). This coupling allows for efficient data transfer and communication between the components, ensuring that the EDT value controller (412) accesses and processes EDT value data in real time. The EDT value controller (412) is an innovative integrated circuit that is implemented in the satellite (101). In an embodiment, the structure of such innovative integrated circuit includes a microcontroller-based hardware circuit that enables dynamic determination and processing of EDT values for the S&F operations in a non-terrestrial network. The EDT value controller (412) is configured to determine an EDT value for the UE (102), wherein the EDT value represents an estimated time required to deliver data to the ground network apparatus (103) from a time the data is sent by the UE (102), and to provide the EDT value for inclusion in a downlink NAS message together with the satellite identifier associated with the satellite (101). The EDT value controller (412) is further configured to include or cause inclusion of the EDT value in a S&F satellite operation parameters IE within the downlink NAS message, and to define and / or signal an applicability scope for the EDT value within at least one of a TAI list, registration area, area, cell, or cell list including cells belonging to the same satellite identifier. The EDT value controller (412) may determine the EDT value based on at least one of orbital characteristics of the satellite (101), a feeder link configuration to the ground network apparatus (103), and feeder link availability conditions, and may update the EDT value responsive to changes in satellite scheduling and / or feeder link availability windows. Any references to “analog components” are optional and non-limiting; in one embodiment, the EDT value controller (412) is implemented predominantly using digital circuitry including an MCU and associated timer / counter circuitry for EDT computation and message-format preparation.

[0163] Further, the EDT value controller (412) determines the EDT value for the UE (102). The EDT value represents an estimated time required to deliver data to the ground network apparatus (103) from the time the data is sent by the UE (102). The EDT value controller (412) generates the NAS message including the EDT value and the satellite (101) identifier associated with the satellite. The EDT value controller (412) transmits the NAS message to the UE (102).

[0164] Furthermore, the EDT value in the EDT value controller (412) is determined based on at least one of the orbital characteristics of the satellite (101) and a feeder link configuration to the ground network apparatus (103). Furthermore, the EDT timer value is valid within at least one of a TAI list, registration area, area cell, or cell list, wherein the cell list includes cells belonging to the same satellite (101) identifier in which the EDT value is received.

[0165] FIG. 5A is a flowchart illustrating a method for managing EDT values in the S&F satellite communication network by a UE (102) according to embodiments disclosed herein. At step 501, the method includes receiving the first NAS message from a first satellite by the UE (102), the UE determines the first satellite e.g. SAT-1 from the broadcast information of the RAN node e.g. eNB or gNB. The first NAS message includes the first EDT value associated with the first satellite. This EDT value represents the estimated time required to deliver data to a ground network apparatus (103) from the time the data is sent by the UE (102) using the first satellite i.e. through the serving satellite from which the EDT value is received in the NAS message for example if the cell broadcasts the SAT-1 as the satellite ID and the NAS message carrying the EDT-1 values is received from this satellite, then EDT-1 value indicate the time it will take to send the data from the UE to ground network through SAT-1 i.e. when cell of SAT-1 is serving the UE. At step 502, the method includes storing the first EDT value associated with the first satellite in a memory of the UE (102) i.e. combination / mapping of SAT-1 and first EDT is stored in the UE. At step 503, the method includes receiving the second NAS message from a second satellite by the UE (102). The second NAS message includes the second EDT value associated with the second satellite), the UE determines the second satellite e.g. SAT-2 from the broadcast information of the RAN node e.g. eNB or gNB. At step 504, the method includes storing the second EDT value associated with second satellite in the memory while maintaining the first EDT value associated with the second satellite stored in the memory of the UE (102). At step 505, the method includes receiving the third NAS message from the first satellite. The third NAS message includes the third EDT value associated with the first satellite. At step 506, the method includes storing the third EDT value by replacing the first EDT value with the third EDT value while maintaining the second EDT value associated with the second satellite.

[0166] FIG. 5B is a flowchart illustrating a method for managing EDT values in the S&F satellite communication network by the ground network apparatus (103) according to embodiments disclosed herein. At step 507, the method includes receiving data from the UE (102) by the ground network apparatus. At step 508, the method includes determining the estimated uplink delivery time duration by the ground network apparatus (103). This estimated uplink delivery time duration indicates the estimated time required to deliver the data to the ground network element from the time the data is sent by the UE (102). At step 509, the method includes encoding the estimated uplink delivery time duration as bytes of a Time Duration Information. At step 510, the method includes identifying a satellite ID of a satellite (101) serving the UE (102) by the ground network apparatus (103). At step 511, the method includes determining the estimated uplink delivery time duration by the ground network apparatus (103). This estimated uplink delivery time duration indicates the estimated time required to deliver the data to the ground network element from the time the data is sent by the UE (102). At step 512, the method includes referencing the satellite ID of the satellite (101) serving the UE (102) for communication with the satellite by the ground network apparatus (103).

[0167] FIG. 5C is a flowchart illustrating a method for managing EDT values in the S&F satellite communication network by the satellite (101) according to embodiments disclosed herein. At step 513, the method includes determining the EDT value for the UE by the satellite (101). This EDT value represents the estimated time required to deliver data to a ground network apparatus (103) from the time the data is sent by the UE (102). At step 514, the method includes generating the NAS message including the EDT value and the satellite identifier associated with the satellite. At step 515, the method includes transmitting the NAS message to the UE (102) by the satellite.

[0168] FIG. 6 is a sequence diagram illustrating the handling of downlink S&F estimated delivery time according to embodiments disclosed herein. At step S1, the UE (102) initiates the NAS procedure, for example, an initial attach procedure, the TAU procedure, or the service request procedure, and transmits the attach request message, the tracking area update request message, or the service request message to the MME on-board the satellite (101) via the available service link. The UE (102) includes S&F capability information in the transmitted message.

[0169] At step S2, in the absence of a feeder link between the MME on-board the satellite (101) and the ground network apparatus (103), the MME on-board the satellite (101) cannot forward the NAS signaling message from the UE (102) to the MME on-ground at the ground network apparatus (103). The MME on-board the satellite (101) computes and includes an uplink S&F estimated delivery time IE in a downlink NAS message, for example, an attach accept message, a tracking area update accept message, or a service accept message transmitted to the UE (102).

[0170] In an embodiment, in addition to the uplink S&F estimated delivery time, the MME on-board the satellite (101) computes and includes a downlink S&F estimated delivery time IE and provides the downlink S&F estimated delivery time IE to the UE (102) in the downlink NAS message. The UE (102) stores the uplink S&F estimated delivery time and the downlink S&F estimated delivery time in a non-volatile memory present at the UE (102).

[0171] Further, the UE (102) stores the uplink S&F estimated delivery time and the downlink S&F estimated delivery time on a per satellite ID basis. The satellite ID is broadcasted by an eNB or a gNB the UE determines the satellited ID from this broadcast information of the RAN node. The UE (102) stores the uplink S&F estimated delivery time and the downlink S&F estimated delivery time separately for each satellite from which the UE (102) has received the respective information as part of the NAS message in step S2.

[0172] At step S3, the UE (102) performs actions to define the scope and validity of the IEs including the uplink S&F estimated delivery time and the downlink S&F estimated delivery time. The EDT is either one of the uplink S&F estimated delivery time or the downlink S&F estimated delivery time, and the present embodiment provides handling of the EDT at the UE (102).

[0173] Further, the UE (102) may perform at least one below actions in any order of combinations:

[0174] a) If the EDT IE coded in the downlink NAS message received at step S2 has a zero value or a specific coding (e.g., with a specific value of 111 or some other value) to deactivate / stop / delete the timer, the UE (102) stops the EDT timer if running and deletes the EDT timer optionally associated with the serving PLMN. The UE (102) may store the EDT values per PLMN and / or per satellite ID and use it when the UE (102) is served by the respective PLMN and / or satellite ID, and when the delete indication is received with a specific coding scheme then that value is deleted for the respective PLMN and / or satellite ID.

[0175] b) If the EDT IE is not included in the downlink NAS message received at step S2, the UE (102) deactivates / stops / deletes the EDT timer if it is running and deletes the previously stored EDT timer value optionally associated with the serving PLMN and / or satellite ID. In an embodiment, the UE (102) may also retain the previously stored EDT timer value and reset the EDT timer values with previously stored EDT timer value optionally associated with the serving PLMN and / or satellite ID.

[0176] c) An AT command can be used to inform upper protocol layers that the UE (102) is in S&F mode of operation and update the uplink or downlink EDT for data delivery, to modify the existing EDT value or to delete the existing EDT timer optionally associated with the serving PLMN and / or satellite ID.

[0177] d) If the UE (102) has a stored / running EDT timer and during NAS signaling, EDT IE is not included in the NAS message, the UE (102) retains the previously stored EDT value. If the value is included, the UE (102) updates the current EDT timer value with the received value in EDT IE and restarts the EDT timer. The UE (102) indicates to the upper layers.

[0178] e) EDT timer value is only valid in a TAI list / registration area / area / cell / cell list, for example, the cell list is the one belonging to same satellite ID in which it was received. The UE (102) determines EDT on a given cell (depending on the satellite ID broadcasted) as the UE (102) stores it per PLMN and / or satellite (i.e., using the satellite ID). In an embodiment, if the UE (102) moves out of the TAI list / registration area / area / cell / cell list, for example, belonging to same satellite ID, the UE (102) deletes the stored EDT value or stops the EDT timer.

[0179] f) If the UE (102) is switched OFF and switched ON and optionally USIM remains same, the UE (102) can:

[0180] i. Store the EDT timer value persistently across power cycle and keep it running after switch ON, or

[0181] ii. Choose to reset the EDT timer value to the stored value, or

[0182] iii. Delete the EDT timer value.

[0183] g) If the UE (102) detects a USIM change or USIM removal / inserting, the UE (102) deletes the stored EDT value and stops the EDT timer.

[0184] h) The UE (102) stores EDT value separately per PLMN and / or per satellite ID. If the UE (102) serving PLMN and / or satellite changes, the UE (102) deletes the previous PLMN's and / or satellite's EDT value and stops the timer. The UE (102) may also maintain a list consisting of EDT values per PLMN and / or per satellite ID and uses / modifies corresponding value from the list when changing PLMNs and / or serving satellite (determined using satellite ID). When a NAS message or the ESM data transport message carrying the user data is sent, the UE (102) determines the time it may take for the data to reach the ground network apparatus (103) based on EDT values stored per PLMN's and / or satellite's EDT value, i.e. from the value received in NAS message when the UE (102) was camped on a given satellite ID.

[0185] For example, the UE (102) is camped on a cell which is broadcasting the SAT-1 and / or PLMN-1. The UE (102) receives EDT-1 as the value of EDT in NAS message. The UE (102) stores it along with SAT-1 and / or PLMN-1.

[0186] Similarly, when the UE (102) is camped on a cell which is broadcasting the SAT-2 and / or PLMN-1, the UE (102) receives EDT-2 as the value of EDT in NAS message. The UE (102) stores it along with SAT-2 and / or PLMN-1.

[0187] Now if the UE (102) sends a NAS message carrying user data or SMS, the UE (102) determines that it will take EDT-1 time to send the data to the ground network apparatus (103) if the UE (102) is camped on a cell which is broadcasting the SAT-1 and / or PLMN-1. Similarly, if the UE (102) sends a NAS message carrying user data or SMS, the UE (102) determines that it will take EDT-2 time to send the data to the ground network apparatus (103) if the UE (102) is camped on a cell which is broadcasting the SAT-2 and / or PLMN-1. The illustration is taking uplink as an example; the same mechanism is applied for the downlink data.

[0188] i) If the UE (102) receives a new value of EDT in the NAS message, for example, an attach accept message or a TAU accept message, then the UE (102) replaces the stored EDT value of the satellite ID and / or PLMN which is broadcasted on the current camped cell.

[0189] For example, if the UE (102) has stored EDT-1 along with SAT-1 and / or PLMN-1, and EDT-2 along with SAT-2 and / or PLMN-1. Now if the UE (102) receives the new EDT value as EDT-3 in a NAS message from the cell which is broadcasting SAT-1 and / or PLMN-1, then the UE (102) should replace the EDT values stored along with SAT-1 and / or PLMN-1 and there is no impact to the EDT values stored along (also can be called as mapped to) with SAT-2 and / or PLMN-1.

[0190] j) If the UE (102) receives a reject cause related to S&F mode of operation or any reject cause, the UE (102) deletes the EDT value optionally stored along with SAT-1 and / or PLMN-1 and stops the timer.

[0191] k) If the UE (102) gets deregistered, for example, moves to the EMM DEREGISTERED STATE, the UE (102) invalidates / deletes any stored EDT value and stops EDT timer.

[0192] In an embodiment, when the EDT value is received, the NAS layer of the UE (102) indicates to upper layers, for example, an application layer, that a new or updated timer value is received by the UE (102), for example, using an AT Command. Using the AT Command, the upper layers in the UE (102) determine the time required to send or receive the data to the ground network apparatus (103) or a target application server or node on a given PLMN and / or satellite ID.

[0193] In an embodiment, the terms deactivate, invalidate, stop, and delete are used interchangeably. This implies the EDT time given to the UE (102) is no longer applicable. If the timer is running, then it has to be stopped. The NAS layer of the UE (102) indicates to upper layers, for example, an application layer, that the timer value indicated in the past is no longer applicable, for example, using an AT Command. Using the AT Command, the upper layers in the UE (102) determine the time required to send or receive data to the ground network apparatus (103) or a target application server or node which is independent of the value received of EDT.

[0194] In an embodiment, when the UE (102) sends data to the ground network apparatus (103), the UE (102) is not aware accurately when the data is delivered in the S&F mode. When the UE (102) receives acknowledgment data from the ground network apparatus (103), the UE (102) is not aware accurately when the data will be delivered to the UE (102) in the S&F mode.

[0195] In an embodiment, the present disclosure relates to the management of estimated delivery times in the UE (102) within a communication network. The scope and validity of IE received in attach accept messages, TAU accept messages, and service accept messages are not clearly defined in the prior art.

[0196] In an embodiment, downlink estimated delivery time refers to the time required to deliver data to the UE (102) from the ground network apparatus (103). The downlink estimated delivery time is indicated to the UE (102). The estimated delivery time can be for either uplink or downlink transmissions or both or round-trip time.

[0197] In an embodiment, a coding mechanism includes an indication with a value of zero or a specific value like 111 which can deactivate the timer. Consequently, the timer is either deleted, deactivated, discarded, or stopped if it is running. If the IE is not included in attach accept messages, TAU accept messages, or service accept messages, the uplink estimated delivery time is deleted except for periodic updates and emergency registrations. Optionally, the estimated delivery time may not be available only for that specific transaction.

[0198] In an embodiment, the EDT value can be per transaction. When the UE (102) sends a service request piggybacked with ESM data transport or uplink user data, in response, a NAS message, for example, a service accept message, can indicate to the UE (102) the EDT.

[0199] In an embodiment, an AT command indicates to upper layers that the UE (102) is in S&F mode and provides the time to deliver data to the UE (102). When an updated value is first received, the previous value is deleted. If the IE is not included, the old value is used.

[0200] In an embodiment, the registration area is applicable only when the UE (102) is within the registration area. If the UE (102) moves out of the registration area, the estimated delivery time is deleted. Both storing and deleting options are available when the UE (102) is switched off and switched on. A change in the USIM results in the deletion of the estimated delivery time. Storage per Public Land Mobile Network (PLMN) is also considered wherein the EDT value is stored per PLMN and the value is updated only when the respective PLMN provides the new value.

[0201] In an embodiment, in cases of rejection when the UE (102) enters a deregistered state, the UE (102) does not consider the previously stored estimated delivery time as valid. The value is considered to be deleted.

[0202] Further, the present invention provides the method to handle estimated delivery time in the S&F mode in the communication system.

[0203] Furthermore, the present invention provides the MME that computes, in addition to uplink S&F estimated delivery time, the IE downlink S&F estimated delivery time and provides the IE downlink S&F estimated delivery time to the UE (102) in the downlink NAS message.

[0204] Furthermore, the present invention provides the UE (102) that stores the uplink S&F estimated delivery time and the downlink S&F estimated delivery time in a non-volatile memory present at the UE (102).

[0205] In an embodiment, the method includes the UE (102) initiating a NAS procedure such as an initial attach procedure, a TAU procedure, or a service request procedure and transmitting the corresponding request message to the MME on-board the satellite (101) via an available service link. The UE (102) includes S&F capability in the message. In the absence of a feeder link between the satellite (101) and the ground network apparatus (103), the on-board MME on the satellite (101) cannot forward the NAS signaling message from the UE (102) to the MME on-ground at the ground network apparatus (103). Consequently, the on-board MME on the satellite (101) computes and includes an IE for uplink S&F estimated delivery time in the downlink NAS message such as an attach accept message, a TAU accept message, or a service accept message transmitted to the UE (102). Further, the on-board MME on the satellite (101) computes and includes an IE for downlink S&F estimated delivery time in the downlink NAS message. The UE (102) stores the uplink and downlink S&F estimated delivery times in non-volatile memory. The present invention provides a method for the UE (102) to handle the EDT, which is either the uplink S&F estimated delivery time or the downlink S&F estimated delivery time. This approach ensures efficient communication and handling of messages in scenarios where direct communication links are unavailable.

[0206] In an embodiment, the UE (102) performs various actions based on the coding of the EDT IE received in downlink NAS messages. If the EDT IE has a zero value or a specific coding (e.g., 111), the UE (102) stops and deletes the running EDT timer optionally associated with the serving PLMN. If the EDT IE is not included in the downlink NAS message, the UE (102) deactivates, stops, or deletes the running EDT timer and optionally deletes the stored EDT timer value associated with the serving PLMN. Alternatively, the UE (102) may retain the previously stored EDT timer value and reset the EDT timer. An AT command informs upper protocol layers of the S&F mode of the UE (102) and updates the EDT for data delivery. The UE (102) retains or updates the EDT timer value based on the presence of the EDT IE in NAS signaling. The EDT timer value is valid only within the TAI list or registration area where it was received. The UE (102) deletes the EDT value or stops the timer if the UE (102) moves out of the TAI list or registration area, is switched off and on, detects a USIM change, or receives a reject cause related to S&F mode. The UE (102) maintains separate EDT values for each PLMN and deletes the previous PLMN's EDT value when the serving PLMN changes. The present invention ensures efficient management of EDT timers, thereby enhancing the performance and reliability of the UE (102) in various network scenarios.

[0207] FIG. 7 is a block diagram of a terminal or user equipment (UE) 700 according to an embodiment of the disclosure.

[0208] The terminal is an electronic device capable of wireless communication, may include a User Equipment (UE), a portable phone, a smartphone, a tablet, an Internet of things (IoT) device, etc., having various form factors, and may perform wireless communication with a base station (BS) through a wireless channel.

[0209] Referring to FIG. 7, the UE 700 may include at least one transceiver (hereinafter, referred to as simply “transceiver”) 701, at least one processor (hereinafter, referred to as simply “processor”) 702, and at least one memory (hereinafter, referred to as simply “memory”) 703. According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the transceiver 701, the processor 702, and the memory 703 of the UE 700 may operate. However, components of the UE 700 are not limited to the exemplary components illustrated in FIG. 7. In another embodiment, the UE 700 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in some embodiments, any combination of the transceiver 701, the processor 702, or the memory 703 may be integrated in the form of one component.

[0210] The transceiver 701 may be a communication circuit or communication circuitry that enables the UE 700 to perform wireless communication with a node or an entity of a network. For example, the transceiver 701 may enable the UE 700 to transmit or receive a signal to or from a BS through cellular communication, or to transmit or receive a signal to or from another UE through cellular communication. For example, the transceiver 701 may support at least one of various cellular communication technologies including 3rd generation (3G), 4th generation (4G), long term evolution (LTE), 5th generation (5G) NR, 6th generation (6G), and various cellular wireless communication technologies supported by the transceiver (701) may include all subsequent generations of evolved wireless communications.

[0211] According to an embodiment, the UE 700 may include a plurality of transceivers. For example, in the case of supporting evolved-universal terrestrial radio access-new radio (E-UTRA-NR) sual connectivity (EN-DC), the UE 700 may include a first transceiver supporting the 4G LTE wireless communication and a second transceiver supporting the 5G NR wireless communication. According to another embodiment, in the case of supporting NR-dual connectivity (NR-DC), the UE 700 may include a plurality of transceivers supporting the 5G NR wireless communication. According to still another embodiment, in the case of supporting near field wireless communication, the UE 700 may separately include a transceiver supporting at least one standard in the group of wireless communication protocol standards as defined in the protocol standards for Bluetooth®, wireless local area network (WLAN) network (including institute of electrical and electronics engineers (IEEE) 802.11-2016 standard or its amendments, e.g., 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be, without being limited thereto).

[0212] According to an embodiment, the transceiver 701 may include various circuit structures used to transmit or receive signals to or from a BS through a wireless channel. The signals may include control information and data. For example, the transceiver 701 may include a radio frequency (RF) transmitter for up-converting and amplifying the frequency of a transmitted signal and an RF receiver for low-noise-amplifying a received signal and down-converting the frequency thereof. The transceiver 701 may output a signal received through a wireless channel to the processor 702 and may transmit, through a wireless channel, a signal output from the processor 702.

[0213] The processor 702 may control general operations of the UE 700 according to embodiments of the disclosure. The processor 702 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processings. The processor 702 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 703, individually, collectively or in any combination thereof. Further, the processor 702 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme.

[0214] The processor 702 may be electrically, operatively, or communicatively coupled to the transceiver 701 to control the transceiver 701.

[0215] The processor 702 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. For example, the processor 702 may include a communication processor (CP) configured to control communication operations and an application processor (AP) configured to control execution of an upper layer (for example, an application layer) . In a specific embodiment, at least a part of the processor 702 may be included in one chip and the other part of the processor 702 may be included in another chip. Otherwise, at least one processor may be included in another component, for example, the transceiver 701 or the memory 703.

[0216] The processor 702 may perform or control or cause an operation of the UE 700 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 702 may control operations of the UE 700 for processing a downlink signal received from a BS or generating and transmitting an uplink signal to a BS. To this end, the processor 702 may execute a computer program, codes, or instructions stored in the memory 703, so as to control other components of the UE 700 to enable execution of various operations.

[0217] The memory 703 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 703 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0218] The memory 703 may be electrically, operatively, or communicatively coupled to the processor 702 and may be accessed by the processor 702.

[0219] The memory 703 may store a computer program, codes, or instructions executable by the processor 702. According to an embodiment, a computer program, codes, or instructions executable by the processor 702 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 703, the processor 702 may perform various functions according to an embodiment of the disclosure.

[0220] According to an embodiment of the disclosure, operations of the UE 700 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 703 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0221] FIG. 8 is a block diagram of a base station (BS) 800 according to an embodiment of the disclosure.

[0222] The BS 800 may perform wireless communication with at least one user equipment (UE) located within the area of the BS 800 through a wireless channel.

[0223] Referring to FIG. 8, the BS 800 may include at least one transceiver (hereinafter, referred to as simply “transceiver”) 801, at least one processor (hereinafter, referred to as simply “processor”) 802, and at least one memory (hereinafter, referred to as simply “memory”) 803. According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the transceiver 801, the processor 802, and the memory 803 of the BS 800 may operate. However, components of the BS 800 are not limited to the exemplary components illustrated in FIG. 8. In another embodiment, the BS 800 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in some embodiments, any combination of the transceiver 801, the processor 802, or the memory 803 may be integrated in the form of one component.

[0224] The transceiver 801 may be a communication circuit or communication circuitry that enables the BS 800 to perform wireless communication with a node or an entity of a network. For example, the transceiver 801 may enable the BS 800 to transmit or receive a signal to or from the UE X00 through cellular communication, or to transmit or receive a signal to or from another network entity through wireless communication. For example, the transceiver 801 may support various cellular communication technologies including 3rd generation (3G), 4thgeneration (4G), long term evolution (LTE), 5th generation (5G) NR, 6thgeneration (6G), and various cellular wireless communication technologies supported by the transceiver (801) may include all subsequent generations of evolved wireless communications.. According to an embodiment, the transceiver 801 may include various circuit structures used to transmit or receive signals to or from a UE through a wireless channel. The signals may include control information and data. For example, the transceiver 801 may include a radio frequency (RF) transmitter for up-converting and amplifying the frequency of a transmitted signal and an RF receiver for low-noise-amplifying a received signal and down-converting the frequency thereof. The transceiver 801 may output a signal received through a wireless channel to the processor 802 and may transmit, through a wireless channel, a signal output from the processor 802.

[0225] Meanwhile, according to an embodiment of the present disclosure, the BS 800 may perform communication with a node or an entity of a network through wired or wireless communication. For example, the BS 800 may perform wired or wireless communication with an adjacent BS, or a node or an entity of a core network through a backhaul network. Although not illustrated in FIG. 8, when the BS 800 performs wired communication, the BS 800 may further include a separate network interface for wired communication in addition to the transceiver 801. The network interface may be referred to as network interface circuitry or communication interface circuitry.

[0226] The processor 802 may control general operations of the BS 800 according to embodiments of the disclosure. The processor 802 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processings. The processor 802 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 803, individually, collectively or in any combination thereof. Further, the processor 802 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme.

[0227] The processor 802 may be electrically, operatively, or communicatively coupled to the transceiver 801 to control the transceiver 801.

[0228] The processor 802 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. In a specific embodiment, at least a part of the processor 802 may be included in one chip and the other part of the processor 802 may be included in another chip. Otherwise, at least one processor may be included in another component, for example, the transceiver 801 or the memory 803.

[0229] The processor 802 may perform or control or cause an operation of the BS 800 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 802 may control operations of the BS 800 for generating and transmitting a downlink signal to a UE or processing an uplink signal received from a UE. Otherwise, the BS 800 may transmit or receive a signal to or from a neighboring BS, transfer a signal received from a UE to an upper node of the network, or transmit a signal transferred from an upper node of the network to a UE. To this end, the processor 802 may execute a computer program, codes, or instructions stored in the memory 803, so as to control other components of the BS 800 to enable execution of various operations.

[0230] The memory 803 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 803 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0231] The memory 803 may be electrically, operatively, or communicatively coupled to the processor 802 and may be accessed by the processor 802.

[0232] The memory 803 may store a computer program, codes, or instructions executable by the processor 802. According to an embodiment, a computer program, codes, or instructions executable by the processor 802 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 803, the processor 802 may perform various functions according to an embodiment of the disclosure.

[0233] According to an embodiment of the disclosure, operations of the BS 800 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 803 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0234] The UE or the base station may perform various communication procedures related to the control plane or the user plane by cooperating with one or more network entities based on wireless communication. For example, the UE may communicate with network entity such as an Access and Mobility Management Function (AMF) or a Session Management Function (SMF) via the base station, or the base station may perform at least one communication procedure by directly transmitting and receiving signals to / from, or relaying signals between, the network entities.

[0235] The structure of the above-described network entity will be described in more detail with reference to the drawings.

[0236] FIG. 9 is a block diagram of a network entity 900 according to an embodiment of the disclosure.

[0237] The network entity 900 may include an entity (apparatus, device, or server, etc.) that performs one or more network functions (NFs) or a part of a network function constituting a core network (e.g., a 5th generation (5G) core (5GC)) in a communication system. In this case, multiple NFs may be implemented within a single network entity, or a single NF may be distributed and implemented across a plurality of network entities. In addition, when an NF is implemented within the network entity, the NF may be implemented in the form of software, and in such a case, a program for operating the NF may be stored in memory of the network entity 900.

[0238] A single NF may be implemented by one or more instances, which may be deployed on the same network entity or distributed across multiple network entities to operate. The instance may be a software unit that logically executes a specific network function, and may be implemented in a form that is decoupled from physical hardware resources. Further, one or more NFs may be implemented in the form of one network slice to operate to satisfy specifications required by a particular service.

[0239] The NF may include at least one of an access and mobility management function (AMF), a session management function (SMF), a local session management function (L-SMF), a user plane function (UPF), a local user plane function (L-UPF), a policy control function (PCF), a unified data management (UDM), a unified data repository (UDR), a network exposure function (NEF), a network repository function (NRF), an application function (AF), a network slice selection function (NSSF), a network data analytics function (NWDAF), a network slice admission control function (NSACF), an authentication server function (AUSF), or a data network (DN).

[0240] Referring to FIG. 9, the network entity 900 may include at least one network interface 901, at least one processor 902 (hereinafter, “processor”), and at least one memory 903 (hereinafter, “memory”). As described above, a NF may be implemented in the form of a physical device such as the network entity 900, or may be virtualized and executed in the form of an instance. When implemented as an instance, the NF need not necessarily include physical components as illustrated in FIG. 9. In such a case, the instance may be logically represented as comprising one or more logical functional elements.

[0241] According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the network interface 901, the processor 902, and the memory 903 of the network entity 900 may operate. However, components of the network entity 900 are not limited to the exemplary components illustrated in FIG. 9. In another embodiment, the network entity 900 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in an embodiment, the network interface 901, the processor 902, or the memory 903 may be integrated in the form of one component.

[0242] The network interface 901 is a collective term for a transmitter part of the network entity 900 and a receiver part of the network entity 900, and may be a communication circuit for transmitting or receiving a signal to or from a user equipment (UE), a base station (BS), or another network entity. Here, the communication circuit may include both a communication circuit for wireless communication and a communication circuit for a wired communication. For example, the network interface 901 may include a circuit, logic, hardware, etc., configured to exchange a control plane message or a user plane message with a UE, a BS, or other core network entities through wireless communication or wired communication. The network interface 901 may operate using various protocols (e.g., non-access stratum (NAS) protocol). The network interface 901 may also be referred to, for convenience of description or depending on implementation, as communication circuitry, network interface circuitry, or a communication interface circuitry.

[0243] The processor 902 may control general operations of the network entity 900 according to embodiments of the disclosure. The processor 902 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processings. The processor 902 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 903, individually, collectively or in any combination thereof. Further, the processor 902 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme. Further, it should be noted that, according to another embodiment, in a case where NF is implemented in the form of an instance, the network function may be not necessarily configured by physical hardware.

[0244] According to an embodiment, the processor 902 may be electrically, operatively, or communicatively coupled to the network interface 901 to control the network interface 901.

[0245] The processor 902 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. In a specific embodiment, at least a part of the processor 902 may be included in one chip and the other part of the processor 902 may be included in another chip. Otherwise, at least one processor may be included in another component, for example, the network interface 901 or the memory 903.

[0246] The processor 902 may perform or control or cause an operation of the network entity 900 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 902 may control operations of the network entity 900 for exchanging a control plane message or a user plane message with a UE, a BS, or other core network entities through wireless or wired communication, using various protocols (e.g., NAS protocol). To this end, the processor 902 may execute a computer program, codes, or instructions stored in the memory 903, so as to control other components of the network entity 900 to enable execution of various operations.

[0247] The memory 903 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 903 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0248] The memory 903 may be electrically, operatively, or communicatively coupled to the processor 902 and may be accessed by the processor 902.

[0249] The memory 903 may store a computer program, codes, or instructions executable by the processor 902. According to an embodiment, a computer program, codes, or instructions executable by the processor 902 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 903, the processor 902 may perform various functions according to an embodiment of the disclosure.

[0250] According to an embodiment of the disclosure, operations of the network entity 900 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 903 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0251] In an aspect, a method for managing estimated delivery time (EDT) values in a store-and-forward (S&F) satellite communication network is provided. The method comprising: receiving, by a User Equipment (UE) (102), a first Non-Access Stratum ( NAS) message from a first satellite, wherein the first NAS message comprises a first EDT value associated with the first satellite, wherein the EDT value represents an estimated time required to deliver data to a ground network apparatus (103) from the time the data is sent by the UE (102) through the serving satellite from which the EDT value is received in the NAS message; storing, by the UE (102), the first EDT value associated with the first satellite (101) in a memory of the UE (102); receiving, by the UE (102), a second NAS message from a second satellite, wherein the second NAS message comprises a second EDT value associated with the second satellite; storing, by the UE (102), the second EDT value associated with the second satellite in the memory while maintaining the first EDT value associated with the first satellite (101) stored at the memory of the UE (102); receiving, by the UE (102), a third NAS message from the first satellite, wherein the third NAS message comprises a third EDT value associated the first satellite; and storing, by the UE (102), the third EDT value by replacing the first EDT value with the third EDT value while maintaining the second EDT value associated with the second satellite.

[0252] In another aspect, the method is provided. The method comprises: transmitting, by the UE (102), each of the stored EDT values associated with the satellite ID and the associated satellite ID stored at the memory of the UE (102) from a NAS layer of the UE (102) to one or more upper layers of the UE (102), wherein the UE (102) transmits each of the stored EDT values using an AT command to inform the upper layers that the UE (102) is in an S&F mode of operation; and determining, by the one or more upper layers in the UE (102), a time required to send or receive the data to the ground network apparatus (103) based on the received EDT value and the satellite currently serving the UE, wherein the UE determines the satellite from the satellite ID information broadcasted by the eNB.

[0253] In another aspect, the method is provided. wherein the UE (102) replaces the first EDT value with the third EDT value by deleting the first EDT value from the memory of the UE (102) and adding the third EDT value without impacting the stored EDT-2 associated with the second satellite.

[0254] In another aspect, the method is provided. each of the EDT values are included in a S&F satellite operation parameters information element (IE) of the corresponding NAS message.

[0255] In another aspect, the method is provided. wherein the NAS message is a registration accept message or a tracking area update accept message.

[0256] In another aspect, the method is provided. wherein the EDT timer value is valid within at least one of a Tracking Area Identifier (TAI) list, registration area, area, cell, or cell list, wherein the cell list comprises cells belonging to same satellite (101) identifier in which the EDT value is received.

[0257] In another aspect, the method is provided. wherein each of the EDT values are stored in the memory of the UE (102) per satellite using a satellite (101) identifier corresponding satellite from where the EDT value is received.

[0258] In another aspect, the method is provided. wherein, determining, by the UE (102) based on the EDT value and the associated satellite identifier, an expected time for receiving an acknowledgment corresponding to data transmitted via the satellite (101) identified by the associated satellite identifier.

[0259] In another aspect, the method is provided. The method comprises: deleting, by the UE (102), all stored EDT values in response to the UE (102) transitioning to a deregistered state.

[0260] In another aspect, the method is provided. In the method, the UE (102) determines the satellite from the satellite ID information broadcasted by the eNB.

[0261] In an aspect, a method for managing estimated delivery time (EDT) values in a store-and-forward (S&F) satellite communication network is provided. the method comprises: receiving, by a ground network apparatus (103), data from a user equipment (UE); determining, by the ground network apparatus (103), an estimated uplink delivery time duration, wherein the estimated uplink delivery time duration indicates an estimated time required to deliver the data to the ground network element from the time the data is sent by the UE (102); encoding, by the ground network apparatus (103), the estimated uplink delivery time duration as bytes of a Time duration information element; identifying, by the ground network apparatus, a satellite ID of a satellite (101) serving the UE (102); and referencing, by the ground network apparatus (103), the satellite ID of the satellite (101) serving the UE (102) for communication with the satellite.

[0262] In another aspect, the method is provided. wherein the satellite ID is an integer type indicating the satellite ID of the serving satellite that provides the estimated uplink delivery time duration.

[0263] In another aspect, the method is provided. wherein the estimated uplink delivery time duration is encoded as three bytes comprising octets 3 to 5 of the Time duration information element.

[0264] In an aspect, a method for managing estimated delivery time information in a store-and-forward (S&F) satellite communication mode is provided. the method comprises: determining, by a satellite, an estimated delivery time (EDT), value for a User Equipment (UE), wherein the EDT value represents an estimated time required to deliver data to a ground network apparatus (103) from the time the data is sent by the UE (102); generating, by the satellite, a Non-Access Stratum (NAS) message comprising the EDT value and the satellite identifier associated with the satellite; and transmitting, by the satellite, the NAS message to the UE (102).

[0265] In another aspect, the method is provided. wherein the EDT value is included in a S&F satellite operation parameters information element (IE) within the downlink NAS message.

[0266] In another aspect, the method is provided. wherein the EDT value is determined based at least one of on orbital characteristics of the satellite (101) and a feeder link configuration to the ground network apparatus.

[0267] In another aspect, the method is provided. wherein the EDT timer value is valid within at least one of a Tracking Area Identifier (TAI) list, registration area, area, cell, or cell list, wherein the cell list comprises cells belonging to same satellite (101) identifier in which the EDT value is received.

[0268] In an aspect, a User Equipment (UE) for managing estimated delivery time (EDT) values in a store-and-forward (S&F) satellite communication network is provided. the UE comprises: a memory (403); a processor (401); and an estimated delivery time (EDT) management controller (404), coupled to the memory and the processor. wherein the EDT management controller (404): receive, by a User Equipment (UE), a first Non-Access Stratum ( NAS) message from a first satellite, wherein the first NAS message comprises a first EDT value associated with the first satellite, wherein the EDT value represents an estimated time required to deliver data to a ground network apparatus (103) from the time the data is sent by the UE (102) through the serving satellite from which the EDT value is received in the NAS message; store the first EDT value associated with the first satellite (101) in a memory of the UE (102); receive a second NAS message from a second satellite, wherein the second NAS message comprises a second EDT value associated with the second satellite; store the second EDT value associated with the second satellite in the memory while maintaining the first EDT value associated with the first satellite (101) stored at the memory of the UE (102); receive a third NAS message from the first satellite, wherein the third NAS message comprises a third EDT value associated the first satellite; and store the third EDT value by replacing the first EDT value with the third EDT value while maintaining the second EDT value associated with the second satellite.

[0269] In an aspect, a ground network apparatus (103) for managing estimated delivery time (EDT) values in a store-and-forward (S&F) satellite communication network is provided. The ground network apparatus comprises: a memory (407); a processor (405); and an estimated uplink delivery time duration Controller (408), coupled to the memory (407) and the processor (405). wherein the estimated uplink delivery time duration controller (408): receive data from a user equipment (UE); determine an estimated uplink delivery time duration, wherein the estimated uplink delivery time duration indicates an estimated time required to deliver the data to the ground network element from the time the data is sent by the UE (102); encode the estimated uplink delivery time duration as bytes of a Time duration information element; identify a satellite ID of a satellite (101) serving the UE (102); and reference satellite ID of the satellite (101) serving the UE (102) for communication with the satellite.

[0270] In an aspect, a satellite (101) for managing estimated delivery time (EDT) values in a store-and-forward (S&F) satellite communication network is provided. The satellite comprises: a memory (409); a processor (411); and an EDT value Controller (412), coupled to the memory (409) and the processor (411). wherein the EDT value controller (412): determine an estimated delivery time (EDT), value for a User Equipment (UE), wherein the EDT value represents an estimated time required to deliver data to a ground network apparatus (103) from the time the data is sent by the UE (102); generate a Non-Access Stratum (NAS) message comprising the EDT value and the satellite identifier associated with the satellite; and transmit the NAS message to the UE (102).

[0271] Meanwhile, although specific embodiments of the present disclosure have been described in detail, various modifications may be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be defined by the claims and equivalents thereof.

[0272] 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 modificationsshouldand 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 preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.

Claims

1.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:transmitting, to a network entity, an uplink non-access stratum (UL NAS) message;receiving, from the network entity, a downlink non-access stratum (DL NAS) message comprising store and forward (S&F) satellite operation parameter information, wherein the S&F satellite operation parameter information comprises information on an estimated S&F uplink delivery time duration; andstoring the estimated S&F uplink delivery time duration provided in the S&F satellite operation parameter information.2.The method of claim 1, further comprising:deleting a previous stored estimated S&F uplink delivery time duration, based on the information on the estimated S&F uplink delivery time duration.3.The method of claim 1, further comprising:providing, to an upper protocol layer, an attention (AT) command comprising the estimated S&F uplink delivery time duration,wherein the estimated S&F uplink delivery time duration indicates an estimated time required to deliver a data to a ground network entity from a time the data is sent by the UE.4.The method of claim 3,wherein the AT command further comprising an identifier (ID) of the network entity.5.The method of claim 1,wherein the S&F satellite operation parameter information further comprises information on a satellite identity (ID), and the estimated S&F uplink delivery time duration is associated with the satellite ID.6.A method performed by a network entity in a wireless communication system, the method comprising:receiving, from a user equipment (UE), an uplink non-access stratum (UL NAS) message; andtransmitting, to the UE, a downlink non-access stratum (DL NAS) message comprising store and forward (S&F) satellite operation parameter information, wherein the S&F satellite operation parameter information comprises information on an estimated S&F uplink delivery time duration,wherein the estimated S&F uplink delivery time duration is stored in the UE.7.The method of claim 6,wherein a previous stored estimated S&F uplink delivery time duration is deleted based on the information on the estimated S&F uplink delivery time duration.8.The method of claim 6,wherein the S&F satellite operation parameter information further comprises information on a satellite identity (ID), and the estimated S&F uplink delivery time duration is associated with the satellite ID.9.A user equipment (UE) comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the UE to:transmit, to a network entity, an uplink non-access stratum (UL NAS) message;receive, from the network entity, a downlink non-access stratum (DL NAS) message comprising store and forward (S&F) satellite operation parameter information, wherein the S&F satellite operation parameter information comprises information on an estimated S&F uplink delivery time duration; andstore the estimated S&F uplink delivery time duration provided in the S&F satellite operation parameter information.10.The UE of claim 9, wherein the instructions further cause the UE to:delete a previous stored estimated S&F uplink delivery time duration, based on the information on the estimated S&F uplink delivery time duration.11.The UE of claim 9, wherein the instructions further cause the UE to:provide, to an upper protocol layer, an attention (AT) command comprising the estimated S&F uplink delivery time duration,wherein the estimated S&F uplink delivery time duration indicates an estimated time required to deliver a data to a ground network entity from a time the data is sent by the UE.12.The UE of claim 11,wherein the AT command further comprising an identifier (ID) of the network entity.13.The UE of claim 9,wherein the S&F satellite operation parameter information further comprises information on a satellite identity (ID), and the estimated S&F uplink delivery time duration is associated with the satellite ID.14.A network entity comprising:at least one processor; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the network entity to:receive, from a user equipment (UE), an uplink non-access stratum (UL NAS) message; andtransmit, to the UE, a downlink non-access stratum (DL NAS) message comprising store and forward (S&F) satellite operation parameter information, wherein the S&F satellite operation parameter information comprises information on an estimated S&F uplink delivery time duration,wherein the estimated S&F uplink delivery time duration is stored in the UE.15.The network entity of claim 14,wherein a previous stored estimated S&F uplink delivery time duration is deleted based on the information on the estimated S&F uplink delivery time duration.

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