VLOS separation based radio and core / base station network controlled NTN

Abstract

Systems and methods for communication include a user equipment "UE"; a first satellite having a first orbit defined by a first radius; a plurality of second satellites each having a second orbit, each second orbit defined by a second radius, where each second radius is smaller than the first radius; and a terrestrial-located core network element, the first satellite being adapted to send a setup request to the terrestrial-located core network element and to configure a second satellite sequence of the plurality of second satellites according to a coverage area, wherein the second satellite sequence is adapted to provide a first user data connection between the UE and the terrestrial positioned core network element, and wherein the first satellite is further adapted to iteratively update the second satellite sequence based on a changed coverage area.

Description

Technical Field

[0001] The present invention relates generally to non-terrestrial networks (NTNs), and more particularly to control and user plane separation in NTNs comprising satellites in different orbits. Background Art

[0002] The further evolution of non-terrestrial networks (NTN) in 5G and / or 6G has been announced by many companies. Several verticals including automotive, drone, track and rail industries request higher throughput for their several scenarios so that they can be reliably served by NTN. Current NTN network / cell capabilities are in the range of several Mbits for LEO (low earth orbit) with VSAT (very small aperture terminal). In order to increase throughput, the concept of VLOS (very low orbit satellite) is considered.

[0003] Embodiments of the present invention are intended to address the expected challenges in VLOS satellite constellations, particularly for 3GPP and 6G evolution. Summary of the invention

[0004] According to one or more embodiments of the present invention, a method for communication is provided, the method comprising: sending, by a first satellite, a setting request from a user equipment "UE" to a core network element located on land; configuring, by the first satellite and based on the setting configuration received from the core network element located on land, a second satellite sequence among a plurality of second satellites according to a coverage area of ​​a second satellite sequence and positions of the UE and the core network element located on land relative to the coverage area, the second satellite sequence comprising a service satellite to serve the UE; providing, by the second satellite sequence, a first user data connection between the UE and the core network element located on land; and changing, by the first satellite, the coverage area of ​​the second satellite sequence based on the change of the second satellite sequence. The invention further comprises configuring a second satellite of the plurality of second satellites to become a new serving satellite included in the sequence when the coverage area of ​​the existing serving satellite no longer includes the UE; and configuring a second satellite of the plurality of second satellites having a coverage area including the terrestrially positioned core network element to be included in the sequence if no second satellite in the sequence currently has a coverage area including the terrestrially positioned core network element, wherein the first satellite has a first orbit defined by a first radius, and wherein each satellite of the plurality of second satellites has a second orbit, each second orbit being defined by a second radius, wherein each second radius is smaller than the first radius.

[0005] According to some embodiments, the plurality of second satellites are Very Low Earth Orbit "VLEO" satellites.

[0006] According to some embodiments, the first satellite is one of: a Low Earth Orbit "LEO" satellite; or a Geosynchronous Equatorial Orbit "GEO" satellite.

[0007] According to some embodiments, the method further comprises: maintaining, by the first satellite, a further user data connection with the UE; and sending data via the further user data connection if the first user data connection is lost.

[0008] According to some embodiments, the first user data connection has a functionality of a secondary user plane and the further user data connection has a functionality of a primary user plane.

[0009] According to some embodiments, the method further comprises preventing camping of the UE on the second satellite sequence.

[0010] According to some embodiments, the first satellite is an anchor cell for the UE.

[0011] According to some embodiments, at least one second satellite of the plurality of second satellites is a non-anchor cell for the UE.

[0012] According to some embodiments, the method further comprises performing, by the first satellite, Non-Access Stratum Signaling "NAS" with the UE.

[0013] According to some embodiments, providing a first user data connection between the UE and the terrestrially located core network element comprises communication via an inter-satellite link "ISL" between satellites included in the sequence.

[0014] According to some embodiments, the method further includes: performing an inter-satellite hybrid automatic repeat request "HARQ" process, wherein the inter-satellite HARQ process includes: sending user data and information related to generating a HARQ redundancy version by the serving satellite to an adjacent second satellite of the sequence before the coverage area of ​​the serving satellite no longer includes the UE.

[0015] According to some embodiments, the method comprises monitoring, by the UE, the first satellite when the UE is in idle mode.

[0016] According to some embodiments, at least two of the plurality of second satellites are operated by different Mobile Network Providers "MNO".

[0017] According to one or more embodiments of the present invention, a system for communication is provided, the system comprising: User Equipment “UE”; a first satellite having a first orbit defined by a first radius; a plurality of second satellites each having a second orbit, each second orbit being defined by a second radius, wherein each second radius is smaller than the first radius; and a terrestrially located core network element, wherein the first satellite is adapted to, in response to a setup request from the UE: · sending the setup request to the terrestrially located core network element; and configuring the second satellite sequence of the plurality of second satellites according to a coverage area of ​​the second satellite sequence and a location of the UE and the terrestrially located core network element relative to the coverage area based on a setup configuration received from the terrestrially located core network element, the second satellite sequence comprising a serving satellite to serve the UE, The second satellite sequence is adapted to provide a first user data connection between the UE and the terrestrially located core network element, and the first satellite is further adapted to: iteratively update the second satellite sequence based on the changed coverage area of ​​the second satellite sequence by: configuring a second satellite of the plurality of second satellites to become a new serving satellite included in the sequence when the coverage area of ​​an existing serving satellite no longer includes the UE; and configuring a second satellite of the plurality of second satellites having a coverage area including the terrestrially located core network element to be included in the sequence if no second satellite in the sequence currently has a coverage area including the terrestrially located core network element.

[0018] According to one or more embodiments, there is provided a satellite adapted to perform the role of the first satellite in the method described above.

[0019] According to one or more embodiments, there is provided a satellite adapted to perform the role of a second satellite in the method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Non-limiting examples of embodiments of the present disclosure are described below with reference to the accompanying drawings. The dimensions of the features shown in the drawings are selected for convenience and clarity of presentation and are not necessarily shown to scale. The subject matter regarded as the present invention is particularly pointed out and explicitly claimed in the concluding portion of the specification. However, the present invention, both as to organization and method of operation, together with its objects, features and advantages, may be understood by reference to the following detailed description when read with the accompanying drawings. Embodiments are illustrated in the figures without limitation, in which like reference numerals indicate corresponding, similar or analogous elements, and in the drawings: Figure 1 An example of visibility duration for a single LEO satellite orbiting at 600 km is shown; Figure 2A and 2BAn example movement of a very low orbit satellite is shown; Figure 3A and 3B A system for communication according to some embodiments of the present invention is shown; Figure 3C An example representation of a first and second radius is shown; Figure 4 An example schematic diagram showing the setting of a connection request according to some embodiments of the present invention; Figure 5 A flowchart showing a method for communication according to some embodiments of the present invention; and Figure 6 A block diagram of an exemplary computing device that may be used with some embodiments of the present invention is shown.

[0021] It should be appreciated that, for simplicity and clarity of illustration, the elements shown in the various figures are not necessarily drawn to scale. For example, for clarity, the size of some of the elements may be exaggerated relative to other elements. Further, reference numerals may be repeated in the various figures to indicate corresponding or similar elements where deemed appropriate. DETAILED DESCRIPTION

[0022] In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be appreciated by those skilled in the art that the present invention may be practiced without these specific details. In other examples, known methods, processes, components, modules, units and / or circuits are not described in detail in order not to obscure the present invention.

[0023] Embodiments of the present invention use different satellites in different orbits. Very low earth orbit (VLEO) satellites, also referred to herein as very low orbit satellites (VLOS satellites), typically orbit at altitudes below 400-450 km (such as at an altitude of 350 km above the surface of a planet). In contrast, low earth orbit (LEO) satellites typically orbit at altitudes of 600-1400 km.

[0024] Another type of satellite that may be used by embodiments of the present invention is a geostationary / geosynchronous satellite, having a geosynchronous orbit (sometimes referred to as a geosynchronous equatorial orbit) and may be referred to as a GEO satellite. A GEO satellite typically orbits at an altitude of 35,786 km above the Earth's equator and has an orbital period equal to the Earth's rotation period, thereby appearing to be in a stationary, fixed position to a ground-based observer.

[0025] As used herein, LEO and / or GEO satellites may be referred to as having a “higher” orbit (e.g., than VLEO / VLOS satellites), and VLEO / VLOS satellites may be referred to as having a “lower” orbit (e.g., than LEO and / or GEO satellites), for example because the LEO and / or GEO satellites orbit at a greater distance from the center of the Earth than the VLEO / VLOS satellites.

[0026] Figure 1 An example of the visibility duration for a single LEO satellite orbiting at 600 km is shown. As can be seen, the satellite's flyby has a peak visibility duration of approximately 4 minutes, decreasing to a minimum visibility duration of approximately 1.5 minutes.

[0027] VLEO satellites typically have smaller cell diameters than LEO satellites, and the smaller distances on the surface of the planet between VLEO satellites and user equipment (UE) (such as a cellular phone) can allow data throughput in the 100 Mbit region, compared to 0.1-1.5 Mbit throughput for user equipment communicating with LEO satellites (depending on antenna and scenario). However, a disadvantage of VLEO satellites is their increased speed due to their lower altitude, and therefore, VLEO satellites do not remain visible (e.g., for communication with user equipment) as long as LEO satellites.

[0028] LEO satellites already play an important role in idle mode procedures for user equipment (e.g., in 3GPP, TR38.821, TS38.101-4, TS38.304 Rel.-17), where LEO satellites move at speeds relative to users on high-speed trains and remain visible for only 2-5 minutes every 12 hours. Connectivity maintenance has been a recognized challenge for LEO NTN-NR connectivity to date, see, e.g., TR38.821: 7.3.2.1.4 Frequent and unavoidable switching Satellites in non-GEO orbits move at high speeds relative to a fixed position on the Earth, resulting in frequent and unavoidable handovers for both stationary and mobile UEs. This can result in significant signaling overhead and impact power consumption, as well as exacerbating other potential challenges related to mobility, such as service interruptions due to signaling latency… From the above analysis, it is concluded that the HO frequencies in LEO NTNs can be similar to the HO frequencies experienced by terrestrial UEs on high-speed trains, however, this represents a worst-case scenario and is not indicative of typical terrestrial networks. Unexpectedly, frequent HO will occur in GEO due to the impact of large cell sizes limiting UE speed. It is further assumed in the LEO scenario that UE speed is a negligible factor in the HO frequency taking into account the relative speed of the satellites, and this will be primarily a problem for LEOs with moving beams.

[0029] The inventors have recognized that the situation will be further exacerbated by the typically much higher speeds of VLEO satellites and their smaller cell diameters (compared to LEO satellites), and therefore, existing idle mode / architecture procedures will fail to take into account the different speeds and visibility of VLEO satellites.

[0030] For example, if you can Figure 2A As can be seen, very low orbit satellites 230_-1, 230_0, 230_1, 230_2 and 230_3, 230_4 and 230_5 (which may be referred to as satellites 230_n, n being an index, or just satellite 230) orbit above a land surface 200, which may be, for example, the surface of the earth.

[0031] The satellite 230_0 has a coverage area 210_0 including the user equipment 201 , and the satellite 230_0 may transmit signals to the user equipment 201 and receive signals from the user equipment 201 .

[0032] Satellites 230_3, 230_4, and 230_5 are within range of the terrestrially located core network element 202 (e.g., have a coverage area, not shown, that includes the terrestrially located core network element 202) and can send signals to and receive signals from the core network element 202. For example, satellite 230_3 can send signal 220_3 to and receive signal 220_3 from core network element 202, satellite 230_4 can send signal 220_4 to and receive signal 220_4 from core network element 202, and satellite 230_5 can send signal 220_5 to and receive signal 220_5 from core network element 202.

[0033] Satellites 230_0, 230_1, 230_2, and 230_3 form a sequence 235 of satellite hops (e.g., the satellites form a connected chain) from user equipment 201 to terrestrially located core network element 202. Sequence 235 is shown as a minimum sequence because satellites 230_4 and 230_5 are also within range of core network element 202, but are not shown as being included in sequence 235.

[0034] Figure 2B 230_0, 230_1, 230_2, 230_3, 230_4, and 230_5 are shown at a later point in time where VLOS satellites 230_-1, 230_0, 230_1, 230_2, 230_3, 230_4, and 230_5 have moved above the land surface 200 (in the figure, the satellite movement direction is shown as moving from left to right). Satellite 230_-2 has "moved in" from the left and represents the cyclic visibility of the satellite, which is due to the satellite being Figure 2A ) is not “visible” at the point in time shown in (eg, to an observer / user equipment near the location shown).

[0035] exist Figure 2A At the time point shown in FIG. 2 , the coverage area 210_0 from the satellite 230_0 including the user equipment 201 has been connected to the satellite 230_0 (at Figure 2B not shown) so that Figure 2B The user equipment 201 is no longer included at the point in time shown in . The satellite 230_-1 has moved so that its coverage area 210_-1 now does include the user equipment 201.

[0036] Similarly, satellite 230_2 has come within range of core network element 202 and can send and receive signals 220_2 to and from core network element 202. Satellite 230_5 has moved out of range of core network element 202 and can no longer send and receive signals to and from core network element 202.

[0037] The (minimum) sequence 235 of satellite hops connecting the user equipment 201 and the core network element 202 now includes satellites 230_- 1 , 230_0 , 230_1 , and 230_2 .

[0038] Therefore, for any satellite network in lower orbit with cells having smaller diameters and satellites moving faster (also increasing Doppler), handover and connection stability become more problematic. Figure 2A and 2BAs shown, satellite 230_0 has already had to handover the connection to user equipment 201 to satellite 230_-1. Subsequent handovers will be required, for example from satellite 230_-1 to satellite 230_-2 as the satellite orbits, which as a very low earth orbit satellite will occur more frequently than LEO satellites due to the increased orbital velocity.

[0039] If the handover density in LEO is comparable to high-speed train handovers, the handover speed for the VLOS constellation is instead in the range of jet aircraft speeds ignoring the movement of the UE itself.

[0040] However, as discussed, many satellites flying in lower orbits have the potential to increase throughput and spectral efficiency. Therefore, in order to grow capacity and address the problems recognized above, a multi-orbit constellation diagram including interworking with existing LEO or GEO satellites is proposed by embodiments of the present invention, which can use a new 3D (e.g., multi-orbit) network architecture to increase capacity and throughput and can be natively part of a 6G system.

[0041] Embodiments of the present invention address link maintenance, i.e., keeping connectivity alive, even at a lower rate. Figure 2A and 2B The problem described in Figure 3A and 3B A solution according to an embodiment of the present invention is presented in FIG.

[0042] Accordingly, the problem that the present invention can solve can be stated as how to balance the increased data throughput using VLEO / VLOS satellites with the increased switching frequency.

[0043] Embodiments of the present invention solve the problem by locating the core network functionality in a satellite in a higher orbit (e.g., GEO or LEO), which has the advantage of stability but the disadvantage of not having such a high throughput. Therefore, embodiments of the present invention further include a constellation diagram of VLOS orbit satellites (e.g., a 3D network) to provide connections arranged by higher orbit satellites that cover the area instantly. Lower orbit satellites provide data user plane functionality arranged by higher orbit control functions, thereby achieving control and user plane separation (CUPS). For example, higher orbit satellites handle core functionality and know which is the next satellite for providing services and which satellites are needed in the connection for the reverse link to the earth, and thus can provide corresponding information to the satellite. Lower orbit satellites effectively operate only as data pumps, while higher orbit satellites handle connection control and configuration, and thus, lower orbit satellites can be used only when the UE is operating in a connected mode (including discontinuous transmission "DTX" and pause situations). Accordingly, when the UE is in idle mode, the lower orbit satellite does not need to perform non-access layer signaling (NAS) processes, such as paging. This also means that the specification of whether there are any SIBs (System Information Blocks) beyond SSBs (Synchronization Signal Blocks) or CD-SSBs (Cell Definition SSBs) is done to a limited level. For example, lower orbiting satellites may only provide SSB-CDs so that the satellite can be identified, where the use is clarified via ISLs (Inter-Satellite Links) during satellite chain initialization (e.g., configuration from the first satellite).

[0044] Thus, because LEO satellites (or even satellites in higher orbits, such as GEO satellites) move less frequently relative to UEs, they can form a constant service basis suitable for less time-critical core network signaling and for keeping general UE connectivity alive.

[0045] Embodiments of the present invention may improve upon existing networks used for vertical deployments such as automobiles, vehicles, and / or first responders (see, e.g., NTN 4V2X in 5GAA; 5G Automotive Association), and may provide a robust architecture to maintain connectivity for use cases such as remotely operated driving, drone control, etc.

[0046] Figure 3A and 3B A system for communication according to some embodiments of the present invention is shown. The system for communication includes user equipment 301, a core network element 302 (such as AMF (Access and Mobility Management Function)) positioned on land, a first satellite 303, and a plurality of second satellites ..., 330_-2, 330_-1, 330_0, 330_1, 330_2, 330_3, 330_4, 330_5, .... The second satellites may be collectively referred to as 330 or 330_n (where n is an index).

[0047] The first satellite 303 can be a GEO or LEO satellite and can be characterized as having a first orbit defined by a first radius R1. For example, in one embodiment, the first satellite can be a LEO satellite having a first radius, e.g., greater than 600 km. The radius R1 can be measured from the center of the planet (e.g., the Earth) above which the first satellite orbits. The radius R1 can be measured from the surface 300 of the planet (e.g., assuming a uniform surface). Figure 3C An example representation of the first radius R1 is shown.

[0048] The plurality of second satellites 330_n can be VLEO / VLOS satellites and can be characterized as each having a second orbit, each second orbit defined by a radius R2_n (where n is the index of the corresponding second satellite). Each second radius R2_n is less than the first radius R1 such that the first satellite 303 is in an "higher" orbit than each of the plurality of second satellites, as Figure 3C shown. The plurality of second satellites can all share a common second radius (e.g., represented only as R2), e.g., the plurality of second satellites can orbit in the same orbital plane. Figure 3C An example representation of the second radius R2_n for satellite 330_-2 (having radius R2_-2) and satellite 330_4 (having radius R2_4) is shown. As Figure 3C shown, R2_-2 < R1 and R2_4 < R1. In some embodiments, R2_-2 can be equal to R2_4 (e.g., some or all of the R2_n can be equal).

[0049] At least two of the plurality of second satellites can be operated by different mobile network providers "MNO". For example, satellites from multiple MNOs can be commandeered (e.g., subject to an agreement) to provide greater potential coverage.

[0050] As Figure 3A shown, the first satellite 303 communicates with each of the UE 301 and the core network element 302 (e.g., is capable of sending / receiving signals to and from it). For example, the first satellite 303 can send and receive signals 350 to and from the user equipment 301 and can send and receive signals 355 to and from the core network element 302. The first satellite 303 also communicates with at least some of the second satellites 330_n (e.g., those second satellites within the range of the first satellite 303).

[0051] The first satellite 303 is adapted to perform several steps in response to a setup request received from the UE 301. For example, the UE 301 may send an SRB1 setup request to the first satellite 303 as a primary cell. In particular, the first satellite 303 sends the setup request to the core network element 302 located on land. The UE performs access to the satellite 303, since the satellite performs all necessary routines and transmissions (SIB signaling) for being an anchor cell, i.e., the UE can camp on it and perform all authentication requests via the core network via the satellite. The VLOS satellite, also referred to herein as the second satellite, may be a non-anchor satellite, i.e., does not provide the necessary system information (SIB for camping and accessing the core network via the satellite). The first satellite 303 may also handle the initial UE P-RACH (physical random access channel) process, since the second satellite 330_n may not be suitable for P-RACH setup, and the purpose of the present invention is to locate the NAS (non-access layer signaling) handling and core functionality in a more stable higher orbit satellite (e.g., the first satellite 303).

[0052] The first satellite 303 configures the second satellite sequence 335 in the plurality of second satellites according to the coverage area of ​​the second satellite sequence 335 and the position of the UE 301 and the core network element 302 relative to the coverage area based on the setting configuration received from the core network element 302. For example, the first satellite 303 can configure (e.g., through signal 360, not all shown) the second satellites 330_0, 330_1, 330_2 and 330_3 to form a second satellite sequence 335. The second satellite sequence 335 includes a service satellite (e.g., 330_0) to serve the UE 301. The sequence 335 can optionally include a second satellite 330_4 (e.g., configured by the first satellite 303 using signal 365), because the satellite is within the range of the core network element 302 and can provide a backup connection 370 to the core network element 302, but embodiments of the present invention can strive to maintain a minimum sequence 335 (e.g., including as few second satellites as possible) to save satellite-to-satellite resources and extend the operational life of the satellite.

[0053] The second satellite sequence 335 is adapted to provide a first user data connection between the UE 301 and the core network element 302. For example, via multiple satellite hops (e.g., connection chains) between the second satellites in the sequence 335, a secondary user data plane in the 3GPP sense is created between the UE 301 and the core network element 302. In the event of a connection failure between the UE 301 and the serving satellite, the UE 301 may indicate to the first satellite 303 (e.g., via SRB1) that the secondary cell (e.g., the second satellite 330_0) is gone. The first satellite 303 may then compose a new sequence for the UE 301 and indicate to the UE 301 which one or more of the second satellites to use for the connection.

[0054] In some embodiments, providing a first user data connection between the UE 301 and the terrestrially located core network element 302 comprises communication between satellites included in the sequence via an inter-satellite link "ISL" 340. For example, in Figure 3A , satellites 330_0, 330_1, 330_2, and 330_3 may communicate via ISLs (e.g., communication between 330_0 and 330_1, communication between 330_1 and 330_2, etc.) to provide a first user data connection between UE 301 and core network element 302. Satellite 330_3 is shown as the last link in the sequence, communicating with core network element 302 via signal 312.

[0055] It should be appreciated that, depending on the distance between UE 301 and core network element 302, a greater or lesser number of intervening second satellites in sequence 335 may be required or sufficient to establish a “reverse link” to a terrestrially located core network element 302.

[0056] In some embodiments, at least one of the plurality of second satellites (e.g., the second satellite in sequence 335) may be a non-anchor cell for UE 301. A non-anchor cell according to 3GPP is a cell that is not suitable for camping or initial access to be performed by the UE towards the core network, since it does not provide necessary system information (SIB) and is thus only used in conjunction with a dedicated mode, i.e., included when the UE has an active data session. In some embodiments, the first satellite 303 is an anchor cell for UE 301. For example, UE 301 may consider a lower orbit VLOS satellite as a secondary cell (i.e., a non-anchor cell), while the UE anchor cell is in a higher orbit. An anchor cell is a cell in which the UE assumes that SSB system information and paging are transmitted. The concepts of anchor and non-anchor cells exist so far, in particular for NB-IoT operators, however, in the present context, these terms are generally applied to cells, e.g., a VLOS satellite is a non-anchor cell. The second satellite may be provided as a non-anchor cell avoiding the UE to camp on the second satellite, which avoids battery drain of the UE due to frequent idle mode mobility and SIB readings due to the frequency of switching between VLOS satellites due to their orbits.

[0057] The second satellite may only provide PSS blocks (packet switched streams) for measurements of connection maintenance, identification and inhibit indication. General SIBs for neighboring cells / frequencies or service configuration may not be provided. This information may be provided by the (e.g. LEO / GEO) first satellite and depending on the UE request and control considerations for service, the so-called "drift" second drift satellite is configured accordingly for handling the user plane via the first satellite through the control network.

[0058] In some embodiments, the UE 301 is prevented from camping on the second satellite sequence 335 (e.g., the UE 301 is prevented from camping on any of the satellites included in the sequence). For example, a VLOS satellite does not provide the necessary system information, i.e., MIB master information, that would allow camping or directly indicate a non-anchor / non-resident cell in its PBCH (Physical Broadcast Channel).

[0059] The first satellite 303 is further adapted to iteratively update the second satellite sequence 335 based on the changed coverage area of ​​the second satellite sequence. The first satellite 303 accomplishes this by being adapted to configure a second satellite of the plurality of second satellites to become a new serving satellite included in the sequence when the coverage area of ​​the existing serving satellite no longer includes the UE 301. The first satellite 303 may also configure a second satellite of the plurality of second satellites having a coverage area including a terrestrially located core network element to be included in the sequence if no second satellite in the sequence currently has a coverage area including a terrestrially located core network element.

[0060] For example, Figure 3A As shown in FIG. 3 , the second satellite sequence 335 includes satellites 330_0, 330_1, 330_2, and 330_3, wherein satellite 330_0 serves as a serving satellite for UE 301. As the satellite moves on the surface of the earth 300, Figure 3B In the case of Figure 2B 301). However, satellite 330_-1 has moved (e.g., drifted) to have coverage area 310_-1 that includes UE 301. The first satellite 303 may configure satellite 330_-1 to become a new serving satellite serving UE 301. The first satellite 303 may do this prior to the change in the serving satellite (e.g., during a predetermined time before the change), for example, the first satellite 303 may prepare satellite 330_-1 (e.g., through configuration 362) to take over as the serving satellite. Satellite 303_0 may have its status as a removed serving satellite (e.g., through reconfiguration from the first satellite 303), and satellite 330_-1 will be considered part of a second satellite sequence 335. Satellite 330_0 may remain in the sequence 335 as an intermediate satellite. This update of the sequence reflects the switch from satellite 330_0 to satellite 330_-1 as the serving satellite.

[0061] At the other "end" of the sequence, satellite 303_4 has moved far enough to have a coverage area that no longer includes core network element 302 (e.g., it is no longer within range), and satellite 303_2 has moved far enough to have a coverage area that now includes core network element 302. Satellite 330_2 may be configured by first satellite 303 to communicate with core network element 302 (e.g., via signal 312). Alternatively, since satellite 330_2 is already included in sequence 335, no further configuration by first satellite 303 may be required. If satellite 303_4 is included, it may be removed from sequence 335 (e.g., by reconfiguration from first satellite 303). Satellite 303_3 still has a coverage area that includes core network element 302, and thus may optionally remain in sequence 335, for example as a backup, redundant, or fail-safe connection 370 to core network element 202 in the event of a connectivity issue with second satellite 330_2. For example, satellite 330_3 may be configured / reconfigured by first satellite 303 using signal 365. Accordingly, updated sequence 335 includes second satellites 330_-1, 330_0, 330_1, 330_2, and optionally 330_3. Once satellite 330_-1 moves out of range of UE 301, first satellite 303 may prepare (e.g., using configuration 362) second satellite 330_-2 to be included in sequence 335 after the next update to the sequence.

[0062] As an example, the sequence 335 may be viewed as being updated by a cyclic shift of the second satellite index, where 330_-1→330_0, 330_0→330_1, ..., and so on, where 330_0 represents a serving satellite (eg, index n=0 represents a serving satellite).

[0063] It should be understood that although Figure 3A and 3B The second satellite of is shown as moving from left to right, but embodiments of the present invention are equally applicable to other movements of satellites in 3D space, such as from right to left in the 2D figure or into or out of the plane of the page. Further, although UE 301 is shown to the left of core network element 302 in 2D space, other arrangements in 3D space are possible.

[0064] In some embodiments, the first satellite 303 may configure a second satellite of the plurality of second satellites having a coverage area including the terrestrially located core network element 302 to be included in the sequence. Figure 3B and 3A If the satellites move from right to left (eg, a reversal of the direction shown), then first satellite 303 may configure “incoming” satellite 330_4 to be included in sequence 335 .

[0065] In some embodiments, the first satellite 303 may maintain a further user data connection with the UE 301. The further user data connection may be a "backup" data connection, e.g., if the first user data connection (e.g., as provided by the second satellite sequence 335) is lost, the first satellite 303 may send and receive data to and from the UE 301 via this further user data connection. For example, signals 350 between the UE 301 and the first satellite 303 and signals 355 between the first satellite 303 and the core network element 302 may represent this further user data plane.

[0066] As discussed, the first user data connection may have the functionality of a secondary user plane, and a further user data connection (between the first satellite and the UE) may have the functionality of a primary user plane.

[0067] In some embodiments, the first satellite 330 performs non-access stratum (NAS) signaling with the UE 301 .

[0068] In some embodiments, the UE 301 monitors the first satellite 303 when the UE is in idle mode.

[0069] In some embodiments of the present invention, the serving satellite may be adapted to perform an inter-satellite hybrid automatic repeat request "HARQ" process. For example, the inter-satellite HARQ process may include sending user data and information related to generating a HARQ redundancy version by the serving satellite to a second adjacent satellite in the sequence before the coverage area of ​​the serving satellite no longer includes the UE. HARQ redundancy versions are a known feature in 3GPP, where each transmission is self-decodable, but also decodable in the event of reception errors in their combination. Therefore, some embodiments of the present invention are related to HARQ processes performed between two satellites, because switching can occur so frequently and avoids having to restart the HARQ process of the ongoing transmission from the beginning at each switch. If the new serving satellite knows the ongoing HARQ process and the redundancy version to be received or generated, it can maintain and finalize the HARQ process in conjunction with the data received from the previous serving satellite.

[0070] like Figure 3A and 3BAs shown in , the serving satellite 330_0 can send data 342 related to generating a HARQ redundancy version when the satellite 330_0 still has a coverage area 310_0 including the UE 301 and before the satellite 330_0 moves so that the coverage area 310_0 no longer includes the UE 301. The serving satellite 330_0 can send such data 342 to the satellite 330_-1 because the satellite 330_-1 is a neighboring satellite that is expected to become a new serving satellite. Therefore, the serving satellite can not only provide data to the user plane, but also forward a portion of the user data to the next serving satellite according to the remaining coverage time to finalize the supply in the event of an error (e.g., a retransmission for the user).

[0071] The latency is reduced to 10ms, but handovers and service satellite changes will occur very frequently, i.e., with less than a minute or only double-digit seconds for service, requiring seamless provision of HARQ processes and data across base stations / satellites. The HARQ process may include several retransmissions of different redundancy versions and thus consume several double-digit milliseconds. As a result, the number of undecided HARQ processes due to subsequent handovers may increase. Therefore, restarting each interrupted process may cause delays, and therefore, the inter-satellite HARQ process according to an embodiment of the present invention may have advantages. For such a process, the provision of relevant information related to the data and the HARQ process may allow for improved throughput and more efficient data sessions.

[0072] Due to the high density of HARQ process interruptions, some embodiments of the present invention provide new functionality within the handover process that provides all necessary information for maintaining and finalizing ongoing HARQ processes during handover.

[0073] Satellites 330_3 and 330_4 may also perform HARQ processes, wherein satellite 330_3 shares data 345 related to generating a HARQ redundancy version for communication with core network element 302 .

[0074] Accordingly, embodiments of the present invention address fast switching speeds by avoiding switching interruptions and maintaining ongoing HARQ processes, utilizing a modified HARQ process including data forwarding that makes switching more robust, and in the event of a failure, the UE still maintains a smaller connection via a higher satellite for connectivity maintenance and avoids an entire radio link failure (RLF).

[0075] One embodiment of the present invention relates to a satellite adapted to perform the role of a first satellite as described herein, such as the first satellite 303. It should be understood that multiple satellites adapted to perform the role of a first satellite may be deployed to give a large coverage area on the earth.

[0076] Another embodiment of the present invention relates to a satellite adapted to perform the role of a second satellite (such as one of a plurality of second satellites 330_n) as described herein. Such a satellite may be part of a constellation of similar satellites.

[0077] Figure 4 An example schematic diagram of setting a connection request according to some embodiments of the present invention is shown. Figure 4 In FIG, the first satellite is a GEO / LEO satellite, and the plurality of second satellites are VLOS satellites. Ground 402 represents a core network element for terrestrial positioning. Figure 4 In , time can be viewed as progressing "downwards".

[0078] exist Figure 4 In the example, UE 401 sends a setup request to GEO / LEO satellite 403 (step 451). In addition to UE capabilities (such as the frequency band used), the setup request may also include UE authentication data and thus drive the rates or services that the UE is allowed to receive.

[0079] The GEO / LEO satellite 403 sends the setup request forward to the ground 402 (step 452). The ground 402 sends the setup configuration to the GEO / LEO satellite 403 (step 453).

[0080] GEO / LEO satellite 403 configures the service VLOS of VLOS satellite 430 (step 454), and configures the drift VLOS (e.g., updates the service VLOS when required) (step 455). Figure 3A As shown in , the first satellite 303 configures the second satellite 330_0 as a service satellite, and the second satellite 330_-1 may be configured as a drift satellite that will take over as a service satellite from the second satellite 330_0 at a future point in time.

[0081] The VLOS satellites 430 establish inter-satellite links (ISLs) between themselves (step 456). Figure 3A As shown in FIG. 4 , inter-satellite link 340 allows a second satellite in sequence 335 to form a connection from the user equipment to core network element 302. Configured VLOS satellite 430 sends a setup request to ground 402 using the configuration from the VLOS configuration (step 457).

[0082] The ground 402 sends a positive acknowledgement that the reverse link has been established to the VLOS satellite 430 (step 458). The GEO / LEO satellite 403 sends a setup positive acknowledgement including the VLOS configuration to the UE 401 (step 459). The UE 401 sends a connection request to the serving VLOS 430 using the VLOS configuration (step 460). The serving VLOS sends a setup positive acknowledgement to the UE 401 (step 461). The UE 401 and the ground 402 are then connected via a user data plane that does not include the GEO / LEO satellite 403 (step 462).

[0083] Figure 5 1 is a flow chart of a method 500 for communication according to some embodiments of the present invention. The method 500 may be performed as follows: Figure 3A and 3B The system shown in is implemented.

[0084] The method 500 includes sending a setup request from a user equipment "UE" to a terrestrially located core network element by a first satellite (step 510). For example, a UE (such as UE 301) may send a setup request (such as for setting up SRB1) to a first satellite (which may be a higher orbit satellite, such as a LEO or GEO satellite, such as first satellite 303). The first satellite has a radius of 1000 m (such as 1000 m). Figure 3C The first satellite may be adapted to relay the setup request to a terrestrially located core network element (such as the terrestrially located core network element 303).

[0085] The method 500 includes configuring, by the first satellite, a second satellite sequence in a plurality of second satellites (step 520).

[0086] For example, the plurality of second satellites may be a set of VLEO / VLOS satellites (such as a constellation diagram), and the second satellite sequence may be a subset of satellites of the set of VLEO / VLOS satellites. Figures 3A-3C Each satellite 330_n in the plurality of second satellites has a second orbit, wherein each second orbit is defined by a second radius (such as, Figure 3C, and each second radius is less than the first radius. For example, the first satellite may be a low earth orbit (LEO) satellite or a geosynchronous equatorial orbit (GEO) satellite in an orbit higher than each of the plurality of second satellites. The plurality of second satellites may be very low earth orbit (VLEO / VLOS) satellites in an orbit lower than the first satellite. The orbits of the second satellites may be the same or may be different, for example, several second satellites may orbit in a first orbital plane and several other second satellites may orbit in a second orbital plane. At least two of the plurality of second satellites may be operated by different mobile network providers "MNOs" so that the plurality of second satellites do not all have to be of the same design.

[0087] The sequence of the configured second satellites may be such as Figure 3A In particular, the configuration performed by the first satellite is based on a setup configuration received from a terrestrially located core network element. The second satellite sequence in the plurality of second satellites is configured based on a coverage area of ​​the second satellite sequence and a location of the UE and / or the terrestrially located core network element relative to the coverage area.

[0088] For example, Figure 3A As shown in FIG. 1 , the second satellites 330_0, 330_1, 330_2, and 330_3 have a coverage area that includes the UE 301 and the core network element 302 and allows the connection of the UE 301 to the core network element 302 (e.g., the total coverage area composed of the individual coverage area 310_0 of the satellite 330_0 combined with the ISL 340 between the intermediate satellites 330_1 to 330_3 and the connection 312 between the satellite 330_3 and the core network element 302). These satellites can be configured as a second satellite sequence 335, which spans multiple satellite hops connecting the UE 301 and the core network element 302. The second satellite sequence includes a serving satellite to serve the UE, for example, the second satellite 330_0 is Figure 3A , has an individual coverage area 310_0 including UE 301, and a second satellite 330_-1 is Figure 3B The serving satellite in has an individual coverage area 310_-1 including UE 301.

[0089] In some embodiments, the second satellite sequence includes neighboring members of the plurality of second satellites, e.g. Figure 3A The satellites 330_0 to 330_3 shown in FIG. Figure 3B Configuring the second satellite sequence by the first satellite may include including or releasing additional satellites for the ISL to reach the ground station, or adjusting their configuration.

[0090] Method 500 may include providing, by the second satellite sequence, a user data connection between the UE and a terrestrially located core network element (step 530). For example, the second satellite sequence may provide a user data connection having the functionality of a primary user plane connection. Figure 3A , the user data connection / primary user plane connection includes: the UE 301 sends / receives a signal 311 to / from the second satellite 330_0; the second satellite 330_0 communicates with the second satellite 330_1, for example via an inter-satellite link 340; the second satellite 330_1 communicates with the second satellite 330_2, for example via an inter-satellite link 340; the second satellite 330_2 communicates with the second satellite 330_3, for example via an inter-satellite link 340; and the second satellite 330_3 sends / receives a signal 312 to / from the core network element 302.

[0091] The method 500 may include: iteratively updating the second satellite sequence based on the changed coverage area of ​​the second satellite sequence by the first satellite (step 540). The updating includes: when the coverage area of ​​the existing serving satellite no longer includes the UE, configuring the second satellite included in the sequence to become a new serving satellite. For example, Figure 3A and 3B As shown in FIG. 1 , the second satellite sequence 335 is updated to account for the changed service area of ​​the second satellite 330_0, which is Figure 3A Service satellite in. Figure 3A The sequence 335 in FIG. 3 includes satellites 330_0, 330_1, 330_2, and 330_3. As satellite 330_0 orbits away from UE 301, satellite 330_-1 may be configured by a higher orbiting first satellite 303 to take over as a serving satellite, and thus, in Figure 3B , sequence 335 has been updated by first satellite 303 to include satellite 330_-1 (new service satellite), satellites 330_0, 330_1, and 330_2. Satellite 330_3 may be removed from the updated sequence to maintain a minimum sequence (and thereby save satellite resources and extend operational life), or may be retained to provide a backup connection to core network element 302.

[0092] The updating may further include configuring a second satellite of the plurality of second satellites having a coverage area including a terrestrially located core network element to be included in the sequence. For example, at the "tail end" of the sequence, as satellite 330_4 orbits away from the terrestrially located core network element, a higher orbiting first satellite may configure satellite 330_1 to communicate with core network element 302, as satellite 330_1 orbits toward the terrestrially located core network element. The term "drift satellite" may be used to refer to a satellite that is not a serving satellite, but is the next in the sequence and is expected to have its corresponding coverage area "drift" into the coverage area for the UE or core network element.

[0093] exist Figure 3A and 3B In the example shown in FIG. 1 , since the satellite moves from left to right, the satellite 330_1 is already in Figure 3A The sequence shown in 335 and Figure 3B However, it should be understood that if Figure 3A and 3B The direction of satellite movement shown in Figure 3A In Figure 3B If the UE is at a later point in time), then as satellite 330_3 moves out of range of core network element 302 and as satellite 330_4 moves into range of core network element 302, first satellite 303 will need to update sequence 335 so that satellite 330_4 is added to sequence 335. A similar process occurs at the other end of the sequence, where satellite 330_-1 leaves as a serving satellite and satellite 330_0 takes over as a serving satellite due to the location of the UE relative to the respective coverage areas 310_-1 and 310_0 of satellites 330_-1 and 330_0.

[0094] Figure 6 A block diagram of an exemplary computing device 100 that may be used with some embodiments of the present invention is shown. For example, one or more of the first or second satellites 303, 330_n as described herein may include a Figure 6 The computing device 100 may include a controller or computer processor 105, which may be, for example, a central processing unit processor (CPU), a chip or any suitable computing device, an operating system 115, a memory 120, a storage 130, an input device 135, and an output device 140, such as a computer display or monitor that displays, for example, a computer desktop system.

[0095] The operating system 115 may be or may include code for performing tasks involving coordination, scheduling, arbitration, or management operations of the computing device 100, such as the execution of a scheduler. The memory 120 may be or may include, for example, a random access memory (RAM), a read-only memory (ROM), a flash memory, a volatile or non-volatile memory, or other suitable memory unit or storage unit. At least a portion of the memory 120 may include a data storage hosted online on the cloud. The memory 120 may be or may include a plurality of different memory units. The memory 120 may store, for example, instructions (e.g., code 125) for implementing the methods disclosed herein. The memory 120 may use a data storage, such as a database.

[0096] Executable code 125 may be any application, program, process, task, or script. Executable code 125 may be executed by controller 105, possibly under the control of operating system 115. For example, executable code 125 may be or may execute one or more applications that perform methods as disclosed herein, such as, Figure 5 . In some embodiments, more than one computing device 100 or components of a device 100 may be used. One or more processors 105 may be configured to implement embodiments of the present invention by, for example, executing software or code.

[0097] Storage 130 may be or include, for example, a hard drive, a floppy drive, a compact disk (CD) drive, a universal serial bus (USB) device, or other suitable removable and / or fixed storage unit. The data described herein may be stored in storage 130 and may be loaded from storage 130 into memory 120 where it may be processed by controller 105. Storage 130 may include cloud storage. Storage 130 may include storing data in a database.

[0098] Input device 135 may be or may include a mouse, keyboard, touch screen or board, or any suitable input device or device combination. Input device 135 may include a receiver, such as an antenna receiver. Output device 140 may include one or more displays, speakers, and / or any other suitable output device or output device combination. Output device 140 may include a transmitter, such as an antenna transmitter. Any applicable input / output (I / O) device may be connected to computing device 100, for example, a wired or wireless network interface card (NIC), a modem, a printer, a universal serial bus (USB) device, or an external hard drive that may be included in input device 135 and / or output device 140.

[0099] Embodiments of the invention may include one or more items (e.g., memory 120 or storage 130) such as a computer or processor non-transitory readable medium or a computer or processor non-transitory storage medium such as, for example, a memory, a disk drive, or a USB flash memory that encodes, includes, or stores instructions (e.g., computer executable instructions) that implement the methods disclosed herein when executed by a processor or controller.

[0100] It is expected that embodiments of the present invention may have an impact on existing or future non-terrestrial network telecommunication architectures and associated standards. For example, embodiments of the present invention may be employed in beyond 5G, 6G, and future NTN architectures. The ongoing development of these standards and the conceptualization and implementation of future standards may rely on the systems and / or methods of the present invention.

[0101] For example, embodiments of the present invention may extend the capabilities of 3GPP and / or 6G standards because sequences of satellites in higher orbits and lower orbits provide control and user plane separation that balances high data throughput with connection stability. The higher orbit satellites provide core functionality and orchestrate the lower orbit satellites used to provide a user data plane between user equipment and core network elements. The lower orbit satellites effectively operate only as data pumps, while the higher orbit satellites handle connection control and configuration, and thus, the lower orbit satellites may be used only when the UE is operating in connected mode. Accordingly, the lower orbit satellites do not need to perform non-access stratum signaling procedures, such as paging, when the UE is in idle mode.

[0102] Unless specifically stated otherwise, as is apparent from the above discussion, it should be appreciated that throughout the specification, discussions utilizing terms such as "process," "compute," "calculate," "determine," and the like refer to the actions and / or processes of a computer or computing system or similar electronic computing device that manipulates and / or transforms data represented as physical (e.g., electronic) quantities within the computing system's registers and / or memories into other data similarly represented as physical quantities within the computing system's memories, registers, or other such information storage, transmission, or display devices.

[0103] Embodiments of the invention may include articles such as computer or processor readable non-transitory storage media, such as, for example, a memory, disk drive, or USB flash memory that encodes, includes, or stores instructions (e.g., computer executable instructions) that, when executed by a processor or controller, cause the processor or controller to implement the methods disclosed herein.

[0104] It should be appreciated that embodiments of the present invention can address one or more of the purposes and / or challenges described in the background technology, and embodiments of the present invention do not have to meet each of the above purposes and / or challenges to fall within the scope of the present invention. Although certain features of the present invention have been particularly illustrated and described herein, many modifications, substitutions, changes and equivalents may be conceived by those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the present invention in form and detail.

[0105] In the above description, an embodiment is an example or implementation of the invention. The various appearances of "one embodiment", "an embodiment" or "some embodiments" do not necessarily all refer to the same embodiments.

[0106] Although various features of the present invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the present invention may be described in the context of separate embodiments for clarity herein, the present invention may also be implemented in a single embodiment. Although the present invention has been described with respect to a limited number of embodiments, it will be appreciated by those skilled in the art that one or more features from a particular embodiment or group of embodiments may be combined with features of another embodiment or group of embodiments.

[0107] Reference in the specification to "some embodiments," "an embodiment," "one embodiment," or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least some but not necessarily all embodiments of the invention.

[0108] It is to be understood that the phraseology and terminology employed herein should not be regarded as limiting but for descriptive purpose only.

[0109] It is to be understood that the details set forth herein are not to be construed as limitations on the application of the invention.

[0110] It should be understood that the terms "comprises", "comprising", "consisting of" and their grammatical variations do not exclude the addition of one or more components, features, steps or integers or groups thereof, and the terms should be understood to specify the components, features, steps or integers.

[0111] If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0112] It should be understood that where the claims or specification refer to "a" or "an" element, such reference should not be construed as meaning that there is only one of the element.

[0113] It should be understood that where the specification states that a component, feature, structure, or characteristic "may," "might," "could," or "could" be included, that particular component, feature, structure, or characteristic is not necessarily included.

[0114] Where applicable, although state diagrams, flow charts, or both may be used to describe embodiments, the invention is not limited to those diagrams or corresponding descriptions. For example, flow need not move through each illustrated box or state or in exactly the same order as illustrated and described.

Claims

1. A method for communication, the method comprising: Sending a setup request from a user equipment "UE" (301) to a terrestrially located core network element (302) by a first satellite (303); configuring, by the first satellite and based on the configuration received from the terrestrially located core network element, a second satellite sequence (335) of a plurality of second satellites (330_n) according to a coverage area of ​​the second satellite sequence (335) and positions of the UE and the terrestrially located core network element relative to the coverage area, the second satellite sequence including a serving satellite to serve the UE; providing a first user data connection between the UE and the terrestrially located core network element by the second satellite sequence; as well as iteratively updating, by the first satellite, the second satellite sequence based on the changed coverage area of ​​the second satellite sequence, wherein the updating comprises: configuring a second satellite of the plurality of second satellites to become a new serving satellite included in the sequence when the coverage area of ​​the existing serving satellite no longer includes the UE; and configuring a second satellite of the plurality of second satellites having a coverage area including the terrestrially located core network element to be included in the sequence if no second satellite in the sequence currently has a coverage area including the terrestrially located core network element, wherein the first satellite has a first orbit defined by a first radius (R1), and Each satellite (330_n) of the plurality of second satellites has a second orbit, each second orbit is defined by a second radius (R2_n), wherein each second radius is smaller than the first radius.

2. The method of claim 1, wherein the plurality of second satellites are Very Low Earth Orbit (VLEO) satellites.

3. A method as claimed in any preceding claim, wherein the first satellite is one of: a low earth orbit (LEO) satellite; or a geosynchronous equatorial orbit (GEO) satellite.

4. A method as claimed in any preceding claim, comprising: maintaining, by the first satellite, a further user data connection with the UE; and sending data via the further user data connection if the first user data connection is lost.

5. The method of claim 4, wherein the first user data connection has a secondary user plane functionality and the further user data connection has a primary user plane functionality.

6. A method as claimed in any preceding claim, comprising: Preventing the UE from camping on the second satellite sequence.

7. The method of any preceding claim, wherein the first satellite is an anchor cell for the UE.

8. The method of any preceding claim, wherein at least one second satellite of the plurality of second satellites is a non-anchor cell for the UE.

9. A method as claimed in any preceding claim, comprising: Non-access stratum signaling (NAS) with the UE is performed by the first satellite.

10. A method as claimed in any preceding claim, wherein providing a first user data connection between the UE and the terrestrially located core network element comprises communication between satellites included in the sequence via an inter-satellite link (ISL).

11. The method of claim 10, comprising: An inter-satellite hybrid automatic repeat request (HARQ) process is performed, the inter-satellite HARQ process comprising: sending user data and information related to generating a HARQ redundancy version by the serving satellite to an adjacent second satellite of the sequence before the coverage area of ​​the serving satellite no longer includes the UE.

12. A method as claimed in any preceding claim, comprising: The first satellite is monitored by the UE when the UE is in idle mode.

13. A method as claimed in any preceding claim, wherein at least two of the plurality of second satellites are operated by different Mobile Network Providers (MNOs).

14. A system for communication, the system comprising: User equipment "UE" (301); A first satellite (303) having a first orbit defined by a first radius (R1); a plurality of second satellites (330_n), each having a second orbit, each second orbit being defined by a second radius (R2_n), wherein each second radius is smaller than the first radius; as well as A core network element (302) for terrestrial positioning, wherein the first satellite is adapted to, in response to a setup request from the UE: Sending the setup request to the terrestrially located core network element; as well as configuring a second satellite sequence (335) of the plurality of second satellites according to a coverage area of ​​the second satellite sequence (335) and a location of the UE and the terrestrially located core network element relative to the coverage area based on a setup configuration received from the terrestrially located core network element, the second satellite sequence comprising a serving satellite to serve the UE, wherein the second satellite sequence is adapted to provide a first user data connection between the UE and the terrestrially located core network element, and The first satellite is further adapted to: The second satellite sequence is iteratively updated based on the changed coverage area of ​​the second satellite sequence by: when the coverage area of ​​the existing serving satellite no longer includes the UE, configuring a second satellite among the plurality of second satellites to become a new serving satellite included in the sequence; and if no second satellite in the sequence currently has a coverage area including the terrestrially located core network element, configuring a second satellite among the plurality of second satellites having a coverage area including the terrestrially located core network element to be included in the sequence.

15. A satellite adapted to perform the role of a first satellite in the method of any of claims 1-13.

16. A satellite adapted to perform the role of a second satellite in the method of any of claims 1-13.

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