Patent Description:
With the development of the new radio (NR) access technologies (i.e., <NUM>), a broad range of use cases including enhanced mobile broadband, massive machine-type communications (MTC), critical MTC, etc., can be realized. To expand the utilization of NR access technologies, <NUM> connectivity via satellites is being considered as a promising application. In contrast to the terrestrial networks where all communication nodes (e.g., base stations) are located on the earth, a network incorporating satellites and/or airborne vehicles to perform some or all of the functions of terrestrial base stations is referred to as a non-terrestrial network.

Spaceborne vehicles include satellites such as Low Earth Orbiting (LEO) satellites, Medium Earth Orbiting (MEO) satellites, Geostationary Earth Orbiting (GEO) satellites, as well as Highly Elliptical Orbiting (HEO) satellites, collectively referred to as "satellites" herein. Airborne vehicles include Unmanned Aircraft Systems (UAS) including tethered UAS and Lighter than Air UAS (LTA), Heavier than Air UAS (HTA), and High Altitude Platforms UAS (HAPs), collectively referred to herein as "UAS platforms.

In some geographic areas, terrestrial networks are not deployed due to economic reasons (e.g., expectation for revenues does not meet a minimum threshold for profitability). Additionally, natural disasters (e.g. earthquakes, floods, etc.) can result in a temporary outage or total destruction of terrestrial network infrastructures, which then need to be repaired or replaced. With the deployment of non-terrestrial networks, service ubiquity and continuity can be achieved even in these "unserved" or "underserved" areas. Furthermore, due to the reduced vulnerability of spaceborne or airborne vehicles to physical attacks and natural disasters, the development of non-terrestrial networks is especially of interest to public safety or railway communication systems.

In non-terrestrial networks, a satellite may be in a Geostationary Earth orbit (GEO), referred to herein as a "GEO satellite," or a Non-GEO orbit (i.e., Low Earth Orbit and Medium Earth Orbit), referred to herein as "Non-GEO satellites. " A GEO satellite remains relatively fixed in location with respect to earth such that it appears to remain at a fixed position in the sky to observers on the ground. However, the Non-GEO satellite moves over the earth, such that it changes its position in the sky over time to observers on the ground. Since the Non-GEO satellite keeps moving/flying over the earth, it must eventually change its wireless connection to an earth station communicating with the satellite. Additionally, the movement of the Non-GEO satellite would cause user equipment devices (UEs), such as mobile terminals (MTs), served by the satellite to change their connections from one satellite to another from time to time. For instance, a Non-GEO satellite can fly over a particular area that is approximately <NUM> kilometers (km) in diameter in just <NUM> minutes. Thus, MTs in this particular area must be handed over from one satellite to a succeeding satellite that flies over the same area every <NUM> minutes.

In conventional terrestrial networks, the mechanism and techniques for handling UE associated information between Radio Access Network (RAN) nodes, or between a RAN node and Core Network (CN) are configured to accommodate and manage the mobility of moving MTs. UE associated information includes information which is specific for an individual UE, such as handover-related information, path switch information, UE context information, etc. However, in non-terrestrial networks with high-speed satellites, resulting in rapidly moving geographic cells, applying existing UE associated information handling techniques to the non-terrestrial networks would result in a number of challenges such as, for example, large signaling overhead, large UE associated information handling delays, etc. Thus, existing systems and methods for handling UE associated information are not entirely satisfactory.

The exemplary embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, exemplary method, device and non-transitory computer-readable medium are disclosed herein. It is understood, however, that these embodiments are presented by way of example and not limitation, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of the present disclosure, which is defined by the appended claims.

In one embodiment, a method performed by a satellite head station, includes: translating a first uplink (UL) tunnel address associated with a core network to a second UL tunnel address associated with the satellite head station, wherein the first and second UL tunnel addresses are each associated with a packet data unit (PDU) session established between the core network and a user equipment device (UE); transmitting the second UL tunnel address to a first satellite base station; and receiving UL data associated with the PDU session from the first satellite base station, wherein a UL tunnel address destination associated with the received UL data is set as the second UL tunnel address.

In a further embodiment, an aspect of the invention provides a non-transitory computer readable medium storing computer-executable instructions that when executed by a computer, cause the computer to perform the above method.

In yet further embodiments, a satellite head station includes: at least one processor configured to translate a first uplink (UL) tunnel address associated with a core network to a second UL tunnel address associated with the satellite head station, wherein the first and second UL tunnel addresses are each associated with a packet data unit (PDU) session established between the core network and a user equipment device (UE); and a transceiver, coupled to the at least one processor, and configured to transmit the second UL tunnel address to a first satellite base station, and receive UL data associated with the PDU session from the first satellite base station, wherein the received UL data has a UL tunnel address destination set as the second UL tunnel address.

Various exemplary embodiments of the present disclosure are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the present disclosure. As would be apparent to those of ordinary skill in the art, after reading the present disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the present disclosure , which is defined by the appended claims.

A typical terrestrial communication network includes one or more base stations (typically known as a "BS") that are located on earth (i.e., not airborne or spaceborne) that each provides geographical radio coverage, and one or more wireless user equipment devices (typically known as a "UE") that can transmit and receive data within the radio coverage. In the terrestrial communication network, a BS and a UE can communicate with each other via a communication link, e.g., via a downlink radio frame from the BS to the UE or via an uplink radio frame from the UE to the BS. The present disclosure provides systems and methods for replacing one or more terrestrial BSs with one or more satellites to provide a non-terrestrial network, in accordance with various embodiments.

<FIG> illustrates an exemplary scenario of a non-terrestrial (NT) network <NUM> in which the techniques, processes and methods described herein can be implemented, in accordance with various embodiments. As shown in <FIG>, the NT network <NUM> includes at least one satellite <NUM>, or alternatively a UAS platform <NUM>, that provides a plurality geographic cells <NUM> for serving user equipment devices (UEs) <NUM> and <NUM> located in one or more of the geographic cells <NUM>. In <FIG>, example UEs are a mobile terminal (MT) <NUM> and a very small aperture terminal (VSAT) <NUM>, which can wirelessly communicate with the satellite/UAS platform <NUM> via a communications link <NUM>, such as service link or radio link in accordance with a new radio (NR) access technology (e.g., a NR-Uu interface).

Satellites and UAS platforms are collectively referred to as "non-terrestrial communication nodes" or "NT communication nodes" herein. In the following description of exemplary embodiments, a satellite is described as the NT communication node. It is understood, however, that alternative embodiments can utilize a UAS platform as the NT communication node while remaining within the scope of the invention.

Referring still to <FIG>, the satellite <NUM> also communicates with a gateway or earth station <NUM> via a communication link <NUM>, which may be a feeder link or radio link in accordance with NR access technologies. The gateway or earth station <NUM> (e.g., a head station) is communicatively coupled to a data network <NUM> via a communication link <NUM>, which may be a physical link such as a fiber optic cable, for example. In accordance with various embodiments, the satellite <NUM> may be implemented with either a transparent or a regenerative payload. When the satellite carries a "transparent" payload (referred to herein as "transparent satellite"), it performs only radio frequency filtering, frequency conversion and/or amplification of signals on board. Hence, the waveform signal repeated by the payload is un-changed. When a satellite carries a regenerative payload (referred to herein as a "regenerative satellite"), in addition to performing radio frequency filtering, frequency conversion and amplification, it performs other signal processing functions such as demodulation/decoding, switching and/or routing, coding/decoding and modulation/demodulation on board as well. In other words, for a satellite with a regenerative payload (re, all or part of base station functions (e.g., a gNB, eNB, etc.) are implemented on board.

<FIG> illustrates a scenario in which a non-terrestrial network <NUM> is implemented with a regenerative satellite <NUM> (i.e., all functions of a base station are implemented on board), in accordance with one embodiment of the invention. In accordance with various embodiments, the satellite <NUM> hosts one or more complete gNBs, which terminate the NG interface(s) from the <NUM> core network <NUM> (<NUM> CN). As shown in <FIG>, the satellite <NUM> is communicatively coupled to a gateway or satellite head station <NUM> via an NG over satellite radio interface (SRI) communication link, which is in turn coupled to the <NUM> CN <NUM> via a NG communication link, in accordance with some embodiments. The gateway or satellite head station <NUM> encapsulates NG packets for transport over the SRI.

<FIG> illustrates a scenario in which a non-terrestrial network <NUM> is implemented with a split architecture, wherein the satellite <NUM> is a regenerative satellite that performs the functions of a distributed unit (DU) base station (gNB-DU) in a split architecture network. In this case, the functions of a base station are split into a base station distributed unit (gNB-DU) and a base station central unit <NUM> (gNB-CU). In accordance with various embodiments, the satellite <NUM> hosts one or more gNB-DUs; the gNB-CU <NUM> is on the ground. In some embodiments, an F1 interface between gNB-CU <NUM> and gNB-DU <NUM> is transported over a Satellite Radio Interface (SRI). As shown in <FIG>, the satellite <NUM> serves one or more UEs <NUM> located in one or cells provided by the satellite <NUM>. The gNB-CU <NUM> is communicatively coupled to a core network <NUM> via a NG interface protocol, in accordance with some embodiments.

<FIG> illustrates a user plane (UP) protocol architecture <NUM> defined in NR for a gNB CU-DU split architecture network. In the illustrated architecture, the SDAP (Service Data Adaptation Protocol) layer and PDCP (Packet Data Convergence Protocol) layer functions are performed by the gNB-CU <NUM> of Figure 2C. While the RLC (Radio Link Control), MAC (Medium Access Control) and PHY (Physical) layers functions are performed by the gNB-DU satellite <NUM> of Figure 2C. The gNB-CU <NUM> and gNB-DU <NUM> are connected via the F1 interface.

Typically, a satellite generates several beams over a given service area bounded by its field of view. The footprints of the beams are typically of elliptic shape each of which can be considered to be a geographic cell of the satellite. <FIG> illustrates an example field view <NUM> of a satellite and a plurality of geographic cells <NUM> formed by the beams (not shown). Different beams generated by a single satellite can operate with different frequencies and PCIs. In other words, from the perspective of the UE, each single elliptic beam shape radiated from the satellite can be regarded as an individual physical cell. That is, beams radiated from a single satellite can generates lots of physical cells. However, in the remaining figures of this disclosure, only a single beam or single cell from one satellite is illustrated in order to simplify the illustration for purposes of discussion.

As discussed above, non-GEO satellites are constantly flying over and moving with respect to the earth in a pre-determined orbit. Because of this constant motion of non-GEO satellites, unique UE associated information handling issues will arise. For example, due to the motion of the satellite, the UE's wireless connection will frequently change from one earth station to another in a predictable manner. Thus, UE associated information must be maintained and managed during a PDU session as the UE switches from one satellite to another.

<FIG> illustrates an exemplary scenario including a non-terrestrial (NT) network <NUM> in which UE handling methods disclosed herein can be implemented, in accordance with some embodiments. The NT network <NUM> includes a satellite head station <NUM> communicatively coupled to a core network <NUM> (e.g., a <NUM> CN) via a next generation (NG) communications link (e.g., a fiber optic line). The NT network <NUM> further includes a first satellite BS <NUM> and a second satellite BS <NUM>, which move to the left in <FIG>. At time T1, the first satellite BS <NUM> covers a particular geographic area <NUM> (i.e., provides cell coverage to the area). As the satellites <NUM> and <NUM> continue to travel, at time T2, the second satellite BS <NUM> takes over coverage of the geographic area <NUM>. Thus, any UE in the geographic area <NUM> desiring to maintain or resume service must execute a handover to the second satellite BS <NUM>. As shown in <FIG>, both first and second satellite BSs <NUM> and <NUM> connect to the same SHS <NUM> on earth.

<FIG> illustrates a possible scenario <NUM> in which the movement of satellites <NUM> and <NUM>, each of which provides geographic cell coverage on the ground, causes the handover of a relatively stationary UE from one satellite to another. As shown in <FIG>, the motion of the satellites <NUM> and <NUM> causes their respective geographic cells <NUM> and <NUM>, defined by the field of view of their respective satellites <NUM> and <NUM>, to move over time. At time T1, a UE <NUM> camped in geographic area <NUM> is contained completely in Cell1 <NUM> of Satellite <NUM>. However, at time T2, the coverage of Cell1 <NUM> has moved significantly to the left such that the UE <NUM> is now at an edge of Cell1 <NUM> and now contained in the coverage area of Cell2 <NUM>, which has also moved in similar fashion to Cell1 <NUM>. Then at time T3, the UE <NUM> is only in Cell2 <NUM> radiated from Satellite2 <NUM>. Thus, at time T3, a handoff from Cell1 <NUM> to Cell2 <NUM> is necessary, and may even be desirable at time T2 when the UE <NUM> is within both cell's geographic areas.

As illustrated in <FIG>, a UE <NUM> that is relatively stationary compared to the satellites <NUM> and <NUM> may require frequent handoffs or re-selection from one satellite/cell to another satellite/cell. Thus, UE associated information must be maintained and managed so that new satellites serving a UE can easily access the UE associated information and resume or continue service to the UE with minimal delays. In accordance with various embodiments, various methods for handling UE associated information in non-terrestrial networks are described below.

In some embodiments, the methods can be applied to NT networks employing regenerative satellites having on-board base stations (e.g., gNBs). <FIG> illustrates an NT network <NUM> having a satellite head station (SHS) <NUM> configured to translate UL and DL tunnel addresses for communications between a core network <NUM> (e.g., <NUM> core network) and a satellite base station <NUM> (e.g., Sat-gNB), as one aspect of handling UE associated information in the NT network, in accordance with some embodiments. For an end-to-end (E2E) packet data unit (PDU) session established between the core network <NUM> and the satellite base station <NUM>, the E2E PDU session spans from the core network <NUM> to the SHS <NUM>, and then from the SHS <NUM> to satellite BS <NUM>. For each E2E PDU session, a UL Transport Network Layer (TNL) Address is allocated by the user plane function (UPF) of the core network <NUM> for delivery of UL PDUs (denoted as "UL TNL Address (UPF)" in <FIG>). For DL PDUs, a DL TNL Address is allocated by the satellite BS <NUM> for delivery of the DL PDUs (denoted as "DL TNL Address (gNB)" in <FIG>).

In accordance with various embodiments, the SHS <NUM> translates the UL TNL Address (UPF) to a second UL TNL address (designated as "UL TNL Address (Sat-HeadSTA)" in <FIG>), which is allocated by the SHS <NUM>. The SHS <NUM> sends the UL TNL Address (Sat-HeadSTA) to the satellite BS <NUM>. For DL transmissions, the SHS <NUM> translates the DL TNL Address(gNB) to the DL TNL Address (Sat-HeadSTA) which is allocated by SHS <NUM> and sends the DL TNL Address (Sat-HeadSTA) to the UPF of the core network <NUM>. In this way, when DL data from the core network <NUM> is transmitted to the UE for a PDU session, the UPF of the core network <NUM> transmits the DL data to the Sat-HeadSTA with the DL TNL Address destination set as DL TNL Address (Sat-HeadSTA). Then the SHS <NUM> forwards the DL data to the satellite BS <NUM> with the DL TNL Address destination set as DL TNL Address (gNB). Similarly, for UL data for the PDU session from the UE to the core network <NUM>, after receiving the UL data from the UE, the satellite BS <NUM> transmits the UL data to the SHS <NUM> with the UL TNL Address destination set as UL TNL Address (Sat-HeadSTA). Then the SHS <NUM> forwards the UL data to the core network <NUM> with the UL TNL Address destination set as UL TNL Address (UPF).

In order to transmit DL and UL data associated with a PDU session, a communication link is established between the core network <NUM> and the satellite BS <NUM> currently serving a UE associated with the PDU session, wherein the communication link passes through or is relayed by the SHS <NUM>. As shown in <FIG>, in some embodiments, the communication link includes a first general packet radio service (GPRS) tunnel protocol for user plane data (GTP-U) tunnel <NUM> associated with a PDU session. A second GTP-U tunnel <NUM> is also established for another PDU session, which may be associated with the same UE or a different UE. Although only GTP-U tunnels are shown, in various embodiments, any number of GTP-U tunnels may be established between the core network <NUM> and the satellite BS <NUM> through the SHS <NUM>. Each GTP-U tunnel has a TNL Address that includes an Internet Protocol (IP) Address and a GTP Tunnel Endpoint Identifier (GTP-TEID).

The translation of TNL addresses by the SHS <NUM> and the GTP-U tunnels formed through the SHS <NUM> facilitates handling of UE associated information when a UE is handed off from one satellite BS to another in an efficient manner, as described in further detail below.

Referring again to <FIG> and <FIG>, as an example scenario, when the UE <NUM> stays within the same geographic area <NUM> during a time period when the first cell <NUM> radiated from the first satellite <NUM> moves out of the geographic area <NUM> and the second cell <NUM>, radiated from the second satellite <NUM>, moves into the geographic area <NUM>, a handoff from the first cell <NUM> to the second cell <NUM> must be performed (i.e., the UE <NUM> must switch its connection from the first satellite BS <NUM> to the second satellite BS <NUM>).

Typically, a single SHS <NUM> can feed multiple (e.g., tens or hundreds of) satellite BSs (e.g., Sat-gNBs), although only two satellite BS are illustrated in the figures for ease of illustration and discussion. When a satellite BS flies from one region to another, it may change its connection from the SHS <NUM> of the original region to a different SHS that provides service to the second region. Thus, the number and identity of satellite BSs served by the SHS <NUM> may change over time as satellite BSs leave its coverage region and new satellite BSs enter its coverage region. In this non-terrestrial environment, it is expected that a large proportion of handovers would occur between two satellites BSs (Sat-gNBs) that are connected to the same SHS <NUM>.

<FIG> illustrates a NT network <NUM> having a SHS <NUM> configured to perform handling of UE associated information after UE handoff, in accordance with an aspect of the invention. The NT network <NUM> further includes a first satellite BS <NUM> (Sat-gNB1), a second satellite BS <NUM> (Sat-gNB2) and a core network <NUM> (5GCN) communicatively coupled to the SHS <NUM>. As discussed above with respect to <FIG>, due to the movement of the satellite BSs <NUM> and <NUM>, although the UE remains in the same geographic area, the UE will perform a handover to switch its connection from the first satellite BS <NUM> to the second satellite BS <NUM>.

After the UE has successfully established a connection with the second satellite BS <NUM>, the second satellite BS <NUM> initiates a path switch procedure for the UE to switch a downlink path associated with the UE. As shown in <FIG>, the second satellite BS <NUM> sends a Path Switch Request (PSR) signal to the SHS <NUM>, wherein the PSR is associated with the UE. The PSR includes the new DL TNL Address (e.g., "DL TNL Addres (gNB) allocated by the second satellite BS <NUM> to switch the PDU session to the new DL TNL Address. With the reception of the PSR signal, the SHS <NUM> determines whether the UE handover is an intra-SHS handover (i.e., both the first and second satellite BSs <NUM> and <NUM> are served by the SHS <NUM>). In some embodiments, the SHS <NUM> can determine whether the handover is an intra-SHS handover via a RAN UE NGAP ID included in the PSR. The ID can uniquely identify the UE associated with the NG interface within the SHS <NUM>. If the RAN UE NGAP ID included in the PSR is recognized by the SHS <NUM>, then the SHS <NUM> determines that the UE handover from one satellite to another is an intra-SHS handover.

If it is determined that the handover is an intra-SHS handover, the SHS <NUM> terminates the path switch procedure (i.e., does not forward the PSR to the core network <NUM>. Instead, the SHS <NUM> responds with a Path Switch Request Acknowledge (PSRA) signal, and sends the PSRA signal directly to the second satellite BS <NUM>. In accordance with some embodiments, the PSRA signal includes a UL TNL Address (e.g., the "UL TNL Address (Sat-HeadSTA)" as described above with respect to <FIG>) for each PDU session. If it is determined that the handover is not an intra-SHS handover, the PATH SWITCH REQUEST is forwarded to the core network <NUM> to be handled in a conventional manner.

As discussed above, since the SHS <NUM> performs TNL address translation and offloads the path switch procedure for intra-SHS handovers from the core network <NUM>, the signaling overhead to the core network <NUM> can be significantly reduced. It should be noted that such intra-SHS handovers can be caused by moving satellites and/or moving UEs. Additionally, the signaling overhead for handling UE associated information as a result of intra-SHS handovers is significantly reduced because the PSR is terminated in the SHS <NUM> (as shown in <FIG>) instead of transferred to the core network every time due to handovers caused by moving satellites and/or moving UEs.

<FIG> illustrates a method of storing UE context information when a UE transitions to an inactive state, in accordance with further embodiments of the invention. To reduce UE power consumption and allow the UE to resume a connection with a BS as soon as possible after it returns to an active state to handle pending incoming data, for example, the radio resource control (RRC) inactive state (i.e., the RRC_INACTIVE state) was introduced in the NR protocols. In NR, when the UE enters into the RRC _INACTIVE state, the UE context is stored both in UE and in the base station serving the UE when it enters the RRC _INACTIVE state, wherein the BS typically determines to move the UE from an active (i.e., RRC_CONNECTED state) to the RRC _INACTIVE state.

In a NT network, when a first satellite BS <NUM> (Sat-gNB1) decides to move a UE <NUM> it is currently connected to from an RRC_CONNECTED state to an RRC _INACTIVE state, the first satellite BS <NUM> sends a RRCRelease message to the UE <NUM>, which instructs the UE <NUM> to enter into the RRC INACTIVE state. The first satellite BS <NUM> also transfers UE context information for the UE <NUM> to a SHS <NUM>, which stores the UE context information in a memory of the SHS <NUM>. In accordance with various embodiments, the UE context includes at least one of the following:.

It should be noted that the sending of the RRCRelease signal and the UE context information can be performed one after another or performed at the same time. The order is determined by the satellite BS <NUM> implementation.

When the UE <NUM> in an RRC INACTIVE state wants to resume its RRC connection (e.g., when there's UL data for transmission, or the UE needs to perform a tracking area update, or the UE needs to perform RAN area update, etc.), the UE initiates a RRC resume procedure. However, due to movement of the satellite BSs that cover a particular geographic area, as discussed above, even when the UE remains relatively stationary, the UE may initiate the RRC resume procedure with a new satellite BS (Sat-gNB2) that is different from the satellite BS (Sat-gNB <NUM>) it was connected to when it entered into an inactive state (e.g., RRC _INACTIVE state). In this scenario, as shown in <FIG>, the UE sends a RRCResumeRequest signal to a second satellite BS <NUM> (Sat-gNB2). Upon receiving the RRCResumeRequest, if the second satellite BS <NUM> decides to resume the RRC connection for the UE <NUM>, the second satellite BS <NUM> initiates a procedure to retrieve the UE context information associated with the UE <NUM> from SHS <NUM>. For example, the second satellite BS <NUM> may send a UE context request that identifies the UE <NUM> and, in response, the SHS <NUM> will transmit the requested UE context information to the second satellite BS <NUM>. After receiving the UE context information, the second satellite BS <NUM> can resume or initiate a PDU session for the UE.

<FIG> illustrates a method of paging one or more satellite BSs, in accordance with further aspects of the invention. As illustrated in <FIG>, when a core network <NUM> (5GCN) transmits DL data for the RRC_INACTIVE UE to the SHS <NUM>, the SHS <NUM> initiates a paging procedure, in accordance with some embodiments of the invention. In some embodiments, the SHS <NUM> sends a paging message to one or multiple satellite BSs (e.g., Sat-gNBs) identified based on one or more tracking areas (TAs) associated with the UE <NUM>. The SHS <NUM> sends a Paging message to the identified one or multiple satellite BSs (e.g. Sat-gNB1 and Sat-gNB2). In some embodiments, the UE context information is embedded in the Paging message. With the reception of Paging message from the SHS <NUM>, the second satellite BS <NUM> sends a paging message over the NR Uu interface to page the UE <NUM>. With the moving of the UE or satellites, the UE may receive the paging message from another satellite BS (e.g., Sat-gNB2) which is different from the satellite BS (e.g. Sat-gNB1) from which the UE entered into the RRC _INACTIVE state. In this way, when the second satellite BS <NUM> (Sat-gNB2) receives the RRCResumeRequest from UE as a response to the paging message, if the second satellite BS <NUM> decides to resume the RRC connection for the UE <NUM>, the UE context is already on board and the RRC connection can be resumed in a prompt and efficient manner.

<FIG> illustrates a block diagram of a satellite head station (SHS) <NUM> that can be configured to implement the various methods described herein. As shown in <FIG>, the SHS <NUM> includes a system clock <NUM>, a processor <NUM>, a memory <NUM>, a transceiver <NUM> comprising a transmitter <NUM> and receiver <NUM>, a power module <NUM>, and a UE Information handling module <NUM>.

In this embodiment, the system clock <NUM> provides the timing signals to the processor <NUM> for controlling the timing of all operations of the SHS <NUM>. The processor <NUM> controls the general operation of the SHS <NUM> and can include one or more processing circuits or modules such as a central processing unit (CPU) and/or any combination of general-purpose microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate array (FPGAs), programmable logic devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable circuits, devices and/or structures that can perform calculations or other manipulations of data.

The transceiver <NUM>, which includes the transmitter <NUM> and receiver <NUM>, allows the SHS <NUM> to transmit and receive data to and from a remote device (e.g., a Sat-gNB). An antenna <NUM> is electrically coupled to the transceiver <NUM>. In some embodiments, the antenna may be a phase-array antenna or other suitable antenna structure suitable for satellite communications. In various embodiments, the SHS <NUM> includes (not shown) multiple transmitters, multiple receivers, and multiple transceivers. In some embodiments, the antenna <NUM> can be a multi-antenna array that can form a plurality of beams each of which points in a distinct direction.

The UE Associated Information (AI) Handling module <NUM> may be implemented as part of the processor <NUM> programmed to perform the functions herein, or it may be a separate module implemented in hardware, firmware, software or a combination thereof. In accordance with various embodiments, the UE AI Handling module <NUM> is configured to perform one or more of the methods or techniques disclosed herein, such as translating UL and DL TNL addresses to facilitate communications between a core network and a satellite BS, handling Path Switch Requests associated with intra-SHS handovers, storing and providing UE context information to assist with intra-SHS handovers, and paging satellite BSs, wherein the paging message contains UE context information, to facilitate with DL communications to a UE with minimal delay. In some embodiments, the UE AI Handling module <NUM> can be implemented as software (i.e., computer executable instructions) stored in a non-transitory computer-readable medium that when executed by processor <NUM>, transform the processor <NUM> into a special-purpose computer to perform the methods and operations described herein.

The various components and modules discussed above are coupled together by a bus system <NUM>. The bus system <NUM> can include a data bus and, for example, a power bus, a control signal bus, and/or a status signal bus in addition to the data bus. It is understood that the modules of the SHS <NUM> can be operatively coupled to one another using any suitable techniques and mediums.

The term "configured to" or "configured for" as used herein with respect to a specified operation or function refers to a processor, device, component, circuit, structure, machine, module, signal, etc. that is physically constructed, programmed, arranged and/or formatted to perform the specified operation or function.

Furthermore, a person of ordinary skill in the art would understand that various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. A processor programmed to perform the functions herein will become a specially programmed, or special-purpose processor, and can be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein.

Claim 1:
A method performed by a satellite head station (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) the method comprising:
translating a first uplink, UL, tunnel address associated with a core network to a second UL tunnel address associated with the satellite head station, wherein the first and second UL tunnel addresses are each associated with a packet data unit, PDU, session established between the core network and a user equipment device, UE;
transmitting the second UL tunnel address to a first satellite base station; and
receiving UL data associated with the PDU session from the first satellite base station, wherein a UL tunnel address destination associated with the received UL data is set as the second UL tunnel address.