Mobile device, network node, method in mobile device, and method in network node

Abstract

To provide a method and an apparatus for solving or alleviating the problem in which, due to the intermittent availability of a non-terrestrial network (NTN) cell, some user equipment (UE) remain out of coverage for a considerable period of time.SOLUTION: A method performed by UE for communication via an NTN includes means for determining whether the UE is inside or outside the coverage of the non-terrestrial network, and means for, based on the determination, transmitting, to a network node, assistance information for setting an unavailability period of the non-terrestrial network caused by coverage loss of the non-terrestrial network.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to wireless communication systems and devices thereof that operate in accordance with 3rd Generation Partnership Project (3GPP) standards or equivalents or derivatives thereof. This disclosure is particularly, but not exclusively, related to improvements related to enhanced power savings for Internet of Things (IoT) devices in so-called Long Term Evolution (LTE) systems ("4G") or "next generation" ("5G") systems that use non-terrestrial portions, including airborne or space-based network nodes. [Background technology]

[0002] In 3GPP standards, a NodeB (or "eNB" in LTE, "gNB" in 5G) is a base station through which communication devices connect to the core network and communicate with other communication devices or remote servers. A communication device may be, for example, a mobile communication device such as a mobile phone, smartphone, smartwatch, personal digital assistant, laptop / tablet computer, web browser, e-reader, etc. End-user communication devices are commonly called User Equipment (UE) and may be operated by a human or consist of automated devices. Such mobile (or generally fixed) devices are typically operated by a user (and therefore are often referred to collectively as User Equipment, "UE"), but may also be connected to IoT devices and similar Machine Type Communication (MTC) devices to connect to the network. For simplicity, this application will use the term base station to refer to such base stations and the term mobile device or UE to refer to such communication devices.

[0003] The latest developments in 3GPP standards cover evolving communication technologies that are expected to support a variety of applications and services, such as MTC, IoT / Industrial IoT (IIoT) communications, vehicular communications and autonomous vehicles, high-definition video streaming, smart city services and / or the like.

[0004] To provide enhanced support for MTC devices, 3GPP introduced the "eMTC" (enhanced MTC) UE category in Release 12 and specified the first low-complexity UE Category 0 (Cat-0), which supports a reduced peak data rate of 1 Mbps, a single antenna, and Half Duplex Frequency Division Duplex (HD FDD) operation. 3GPP Release 13 introduced support for so-called "Cat-M1" UE, which allows for further cost reductions by reducing the transmit and receive bandwidth to 1.08 MHz and introducing lower UE power classes of 20 dBm in addition to 23 dBm. Cat-M1 UE operates in narrowband (NB) and may also support Coverage Enhanced (CE) operation. In LTE Releases 14 and 15, a new UE category, Cat-M2, was specified with a 5 MHz transmit and receive bandwidth.

[0005] In Release 13, 3GPP introduced Narrowband Internet of Things (NB-IoT) UE operation with a total baseband bandwidth of 180 kHz. NB-IoT supports operation on anchor carriers (where the UE expects certain signals and channels to be transmitted) and non-anchor carriers (where such signals and channels are not expected to be transmitted). Like eMTC, NB-IoT utilizes increased acquisition time and time repetition to extend system coverage. However, unlike MTC, NB-IoT does not support measurement reporting and handover in connected mode.

[0006] 3GPP is also working on specifying integrated satellite and terrestrial network infrastructure. For example, 3GPP Technical Report (TR) 36.763 V17.0.0 is a study on Narrowband Internet of Things (NB-IoT) / Extended Machine Type Communication (eMTC) Support for Non-Terrestrial Networks in Release 17. The term non-terrestrial network (NTN) refers to a network or segment of a network that uses aircraft or spacecraft for transmission. A satellite refers to a spacecraft in a geostationary Earth orbit (GEO) or non-geostationary Earth orbit (NGEO), such as a low Earth orbit (LEO), medium Earth orbit (MEO), or highly elliptical orbit (HEO). An aircraft refers to a high altitude platform (HAP), including an unmanned aircraft system (UAS). This includes tethered UAS, lighter-than-air UAS, and heavier-than-air UAS, all of which operate quasi-stationary, typically at altitudes between 8 and 50 km.

[0007] 3GPP TR38.811 V15.4.0 is a study on new radios supporting such non-terrestrial networks. This study includes, among other things, a description of NTN deployment scenarios and related system parameters (architecture, altitude, orbit, etc.), and adaptation of 3GPP channel models for non-terrestrial networks (propagation conditions, mobility, etc.). 3GPP TR38.821 V16.1.0 provides more details on NTNs.

[0008] NTN Access typically includes (among other things): NTN Terminal: May refer to a 3GPP UE or a terminal specific to the satellite system if the satellite does not provide direct service to the 3GPP UE. -Service link refers to the radio link between user equipment and a space / air platform (sometimes in addition to the radio link with a ground-based Radio Access Network (RAN)). -Space or airborne platforms. - A gateway connecting the satellite or aeronautical access network to the core network ("NTN Gateway"). It will be understood that the Gateway will likely be co-located with the base station. - Feeder link refers to the radio link between the gateway and the space / air platform.

[0009] A satellite or aircraft may generate multiple beams over a given area to serve each NTN cell, with the beams having a typically elliptical footprint on the Earth's surface.

[0010] 3GPP plans to support three types of NTN beams or cells: - Fixed Earth cells characterized by beams that always cover the same geographic area (e.g. GEO satellites or High Altitude Platform Stations (HAPS)). -Quasi-Earth fixed cells characterized by beams that cover one geographic area during a finite period and a different geographic area during another period (e.g., NGEO satellites that generate steerable beams). -Earth moving cells characterized by beams that cover one geographic area at one moment and a different geographic area at another moment (e.g., NGEO satellites that generate fixed or non-steerable beams).

[0011] For example, if a satellite or aircraft is fixed in altitude / azimuth relative to a specific point on the Earth, such as GEO and UAS, then the beam footprint is fixed on the Earth.

[0012] If the satellite is orbiting the Earth (e.g., LEO) or in an elliptical orbit around the Earth (e.g., HEO), the beam footprint may move around the Earth as the satellite or aircraft moves in its orbit. Alternatively, the beam footprint may be temporarily Earth-fixed (or quasi-Earth-fixed), in which case an appropriate beam-pointing mechanism (mechanical or electronic steering) can be used to compensate for the satellite or aircraft motion.

[0013] LEO satellites may have steerable beams, in which case the beams are temporarily directed to a substantially fixed footprint on Earth. In other words, the beam footprint (representing a NTN cell) remains stationary on the ground for a period of time before changing its focal area to another NTN cell (due to the satellite's orbital movement). From a cell coverage / UE perspective, cell changes occur periodically at discrete intervals, even when these beams serve the same land area (have the same footprint), because different physical cell identities (PCIs) and / or synchronization signal / physical broadcast channel (PBCH) blocks (SSBs) must be assigned for each service link change. In LEO satellites without steerable beams, the beams (cells) constantly move across the Earth in a sweeping motion as the satellite moves along its orbit. Also, as with steerable beams, service link changes and resulting cell changes occur periodically at discrete intervals. Similar to service link changes, feeder link changes also occur periodically due to the satellite's orbital movement.

[0014] As stated in 3GPP TR36.763, 3GPP's current approach is that existing cellular IoT features specified up to Release 16 (such as 4G / 5G core network, Early Data Transmission (EDT), Preconfigured Uplink Resources (PUR), and Self-Organizing Network (SON) features) can be enabled in NTN deployments, as long as they do not require significant modifications to adapt to NTN.

[0015] However, there are many features of NB-IoT operation that are yet to be specified, including support for a 5G core, adaptation of existing mobility mechanisms (new parameter values, timing, etc.) to adapt the functionality to NTN, support for discontinuous coverage without excessive UE power consumption or excessive failure / recovery actions, and enhancements to existing power saving mechanisms such as discontinuous reception (DRX), enhanced DRX (eDRX), power saving mode (PSM), mitigated monitoring, and wake-up signals (WUS).

[0016] The inventors have realized that satellite / aircraft movement or beam hopping (i.e., intermittent availability of NTN cells) can cause some UEs to be out of coverage for significant periods of time. In the worst case scenario, a UE may be in communication coverage only for a short period while a satellite passes. The UE can be configured to use (e)DRX / PSM and wake up for paging monitoring and data transfer. In this case, the network can page the UE only when it is in coverage and enters an active period according to idle state using the (e)DRX / PSM configuration. If the UE's wake-up window (determined by eDRX or PSM) does not match the coverage window of the NTN portion of the network (determined by the UE's location and / or satellite orbits and may not be recognized by the network), the paging may not reach the UE, leading to unnecessary delays and wasted system resources (because the UE must wake up during the overlapping portion of the paging window and coverage window). This potential problem is illustrated in Figure 5, where the UE is unable to receive the page in scenario B (when the paging window and the UE's coverage window do not overlap).

[0017] In legacy systems, power saving mode is set up in Radio Resource Control (RRC) connected mode using appropriate Non-Access Stratum (NAS) signaling. Figure 6 shows an example of the procedure for setting PSM (P1) and releasing PSM (P2) for a UE. PSM operation relies on two timers (T3324 and T3412), whose values ​​are set by the core network and indicated to the UE by a core network node (e.g., Mobility Management Entity (MME), Access and Mobility Management Function (AMF), or other named entity). After obtaining permission to use PSM, the UE enters power saving mode upon expiration of T3324 (which is (re)initiated as soon as the UE enters idle mode). The UE exits power saving mode upon initiating mobile-originated data or signaling. The network can adjust the PSM timer values ​​associated with each UE with certain restrictions, but the network must take into account the UE's potentially discontinuous coverage. If multiple UEs (e.g., UEs served by the same satellite) have similar coverage windows and similar PSM configurations, it is likely that cell switches and associated TAU signaling will occur substantially simultaneously for these UEs, causing peak loads.

[0018] If a UE is configured for eDRX, it monitors paging occasions only during the associated Paging Transmission Window (PTW). The specific PTW used is determined based on the UE's identifier (UE-ID). While the PTW length and eDRX cycle are configurable per UE, the PTW positions of different UEs are evenly distributed in time based on their associated UE-IDs. Figure 10 illustrates a scenario in which two UEs ("UEx" and "UEy") have the same (or substantially the same) eDRX configuration but different PTWs determined by their associated UE-IDs. This method works well when all UEs are always (or nearly always) in coverage, but may not work well in discontinuous coverage scenarios that can occur in NTNs.

[0019] If the UE is out of coverage for a relatively short amount / part of time, this issue may be negligible. However, if the UE is out of coverage for a relatively long amount / part of time, current eDRX techniques may not be able to properly match the UE's PTW with its coverage window, and may not be able to adapt the PTW to a coverage window that may change over time due to UE movement. [Prior art documents] [Non-patent literature]

[0020] [Non-Patent Document 1] 3GPP Technical Report (TR) 36.763 V17.0.0 [Non-patent document 2] 3GPP TR 38.811 V15.4.0 [Non-patent document 3] 3GPP TR 38.821 V16.1.0 [Non-patent document 4] 3GPP Technical Specifications (TS) 38.300 (V16.6.0) [Non-Patent Document 5] 3GPP TS 37.340 (V16.6.0) Summary of the Invention [Problem to be solved by the invention]

[0021] It is therefore an object of the present invention to provide a method and associated apparatus that addresses or at least alleviates (at least some of) the above-mentioned problems. To facilitate understanding by those skilled in the art, the present invention will be described in detail in the context of 3GPP systems (LTE / 5G networks, including NTN), but the principles of the present invention can be applied to other systems as well. [Means for solving the problem]

[0022] In one aspect, the present disclosure provides a method for a user equipment (UE) to communicate over a non-terrestrial network, the method comprising: determining whether the UE is within coverage of the non-terrestrial network or is out of coverage of the non-terrestrial network; and initiating a power saving procedure for the UE based on the determination.

[0023] In one aspect, the present disclosure provides a method of a network node for communicating with a user equipment (UE) over a non-terrestrial network, the method comprising: transmitting information to the UE for controlling power saving based on a determination of whether the UE is in-coverage or out-of-coverage based on a value; and initiating the power saving procedure of the UE based on the determination.

[0024] In one aspect, the present disclosure provides a user equipment (UE) for communicating over a non-terrestrial network, the UE comprising: means for determining whether the UE is within coverage of the non-terrestrial network or out of coverage of the non-terrestrial network; and means for initiating a power saving procedure for the UE based on the determination.

[0025] In one aspect, the present disclosure provides a network node for communicating with a user equipment (UE) over a non-terrestrial network, the network node comprising: means for transmitting information to the UE for controlling power saving based on a determination of whether the UE is in-coverage or out-of-coverage based on a value, and initiating the power saving procedure of the UE based on the determination. [Effects of the Invention]

[0026] Aspects of the present invention extend to corresponding systems and computer program products, such as a computer-readable storage medium having stored thereon instructions operable to program a programmable processor to perform the methods described in the above aspects and possibilities or as claimed, and / or to programming a computer suitably adapted to provide an apparatus as claimed in any of the claims.

[0027] Each feature disclosed in this specification (which term includes claims) and / or shown in the drawings may be incorporated into the present invention independently (or in combination with) other disclosed and / or shown features. In particular, but without limitation, any feature of a claim depending from a particular independent claim may be introduced into that independent claim in any combination or individually. [Brief explanation of the drawings]

[0028] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0029] [Figure 1] FIG. 1 illustrates schematically a mobile (cellular or wireless) telecommunications system in which embodiments of the present disclosure may be applied.

[0030] [Figure 2] FIG. 2 is a schematic block diagram of a mobile device forming part of the system shown in FIG.

[0031] [Figure 3] FIG. 3 is a schematic block diagram of an access network node (e.g., a base station) or NTN node (e.g., a satellite / UAS platform) forming part of the system shown in FIG.

[0032] [Figure 4] FIG. 4 is a schematic block diagram of a core network node (e.g., MME, AMF, etc.) forming part of the system shown in FIG.

[0033] [Figure 5] FIG. 5 illustrates schematically two possible scenarios during power save mode operation in a non-terrestrial network.

[0034] [Figure 6] FIG. 6 shows a schematic diagram of the procedure for setting and canceling the power saving mode.

[0035] [Figure 7] FIG. 7 illustrates several example ways in which the present disclosure may be implemented by the UE illustrated in FIG.

[0036] [Figure 8] FIG. 8 illustrates several example ways in which the present disclosure may be implemented by the UE illustrated in FIG.

[0037] [Figure 9] FIG. 9 schematically illustrates several example ways in which the present disclosure may be implemented by the UE shown in FIG.

[0038] [Figure 10] FIG. 10 schematically illustrates several example ways in which the present disclosure may be implemented by the UE shown in FIG.

[0039] [Figure 11] FIG. 11 schematically illustrates several example ways in which the present disclosure may be implemented by the UE shown in FIG.

[0040] [Figure 12] FIG. 12 illustrates, in schematic form, some exemplary architectural options for providing NTN functionality in the system of the present disclosure shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0041] <Summary>

[0042] FIG. 1 illustrates schematically a mobile (cellular or wireless) telecommunications system 1 in which embodiments of the present disclosure may be applied.

[0043] In this system 1, users of mobile devices 3 (UEs) can communicate with each other and with other users via access network nodes, respective satellites 5 and / or base stations 6, and data network 7 using an appropriate 3GPP Radio Access Technology (RAT), e.g., E-UTRA (4G) and / or NR (5G) RAT. In the case of the E-UTRA RAT, the base stations 6 may be referred to as “eNBs” or “ng-eNBs,” and in the case of the NR RAT, the base stations 6 may be referred to as “gNBs.” The UEs 3 may include NB-IoT or MTC UEs or may include appropriate NB-IoT or MTC functionality. Those skilled in the art will appreciate that while FIG. 1 shows three UEs 3, one satellite 5, and one base station 6 for illustrative purposes, a system, when implemented, would typically include other satellite / UAS platforms, base stations / RAN nodes, and mobile devices (UEs).

[0044] It will be understood that a number of base stations 6 form a (Radio) Access Network or (R)AN, and a number of NTN nodes 5 (satellite and / or UAS platforms) form a non-terrestrial network (NTN). Each NTN node 5 is connected to an appropriate gateway (co-located with the base station 6 in this case) using a so-called feeder link, and is connected to a respective UE 3 via a corresponding service link. Thus, when served by an NTN node 5, a mobile device 3 communicates data to and from a base station 6 via the NTN node 5 using the appropriate service link (between the mobile device 3 and the NTN node 5) and the feeder link (between the NTN node 5 and the gateway / base station 6). In other words, the NTN forms part of the (R)AN, but may also provide satellite communication services independently of E-UTRA and / or 5G communication services.

[0045] Although not shown in Figure 1, adjacent base stations 6 are connected to each other via appropriate inter-base station interfaces (such as the so-called "X2" interface, "Xn" interface, etc.) The base stations 6 are also connected to data network nodes via appropriate interfaces (such as the so-called "S1", "NG-C", "NG-U" interfaces, etc.).

[0046] The data (or core) network 7 (e.g., EPC for LTE, NGC for NR / 5G) typically supports communications in the telecommunications system 1 and includes logical nodes (or “functions”) for subscriber management, mobility management, charging, security, and call / session management (among other things). The data network 7 typically includes user plane entities and control plane entities. The so-called Mobility Management Entity (MME) 9 in 4G, or Access and Mobility Management Function (AMF) in 5G, is responsible for handling connection and mobility management tasks for mobile devices 3, including configuration of power saving mechanisms. The data network 7 may also be coupled to other data networks, such as the Internet or similar Internet Protocol (IP)-based networks (not shown in FIG. 1).

[0047] Each NTN node 5 controls multiple directional beams in which associated NTN cells may be provided. Specifically, each beam has an associated footprint on the Earth's surface that corresponds to the NTN cell. Each NTN cell (beam) has an associated Physical Cell ID (PCI) and / or Beam ID. The beam footprint may be moving as the NTN node 5 moves along its orbit. Alternatively, the beam footprint may be fixed to the Earth, in which case an appropriate beam pointing mechanism (mechanical or electronic steering) may be used to compensate for the movement of the NTN node 5.

[0048] The network and mobile device 3 may also support one or more power saving mechanisms such as discontinuous reception (DRX) and enhanced DRX (eDRX), power saving mode (PSM), relaxed monitoring, and wake-up signals (WUS).

[0049] The PSM may be configured for a compatible mobile device 3 in a radio resource control (RRC) connected mode as generally shown in the procedure designated "P1" in FIG.

[0050] To configure a PSM for a mobile device 3, the network (in this case, core network node 9) provides values ​​for two timers related to power save mode operation (applicable to that mobile device 3). The first timer (also known as "T3324") controls how long the mobile device 3 must remain in RRC idle mode before activating a PSM. The second timer (also known as "T3412") controls how often the mobile device 3 must perform periodic Tracking Area Updates (TAUs). Effectively, the second timer controls the maximum length of each power save mode activation, because upon expiration of the second timer, the mobile device 3 must enter RRC connected mode to send a TAU message (to inform the network / core network node about the mobile device 3's current location). Alternatively, the mobile device 3 may enter RRC connected mode (and cancel the PSM) before the second timer expires, for example, if it has uplink data to send (which cannot be delayed) or if it moves to a different tracking area.

[0051] In this system, when the mobile device 3 enters RRC idle mode, it starts a first timer (T3324) and begins monitoring whether the mobile device 3 is in-coverage or out-of-coverage to control (start and end) power saving mode operation. Specifically, the mobile device 3 activates a PSM if it moves out of coverage while the first timer is running. If the mobile device 3 remains in coverage while the timer is running, it activates a PSM when the timer expires.

[0052] The network may provide satellite information to the mobile device 3 via broadcast information or dedicated signaling (e.g., access stratum signaling or non-access stratum signaling). Based on the satellite information and (if available) the UE location, the mobile device 3 may predict or estimate a future in-coverage window (or windows). The mobile device 3 may suspend monitoring whether the mobile device 3 is in-coverage or out-of-coverage until the predicted in-coverage window.

[0053] When the second timer (T3412) expires, the mobile device 3 remains in PSM as long as it is determined to be out of coverage (based on monitoring) or is predicted to be out of coverage (based on prediction). Similarly, if uplink data arrives (e.g., before the second timer expires), the mobile device 3 remains in PSM as long as it is out of coverage. Thus, the mobile device 3 can effectively extend PSM activation and achieve further power savings depending on the available coverage.

[0054] Optionally, the RRC idle mode mobile device 3 may be configured to run the first timer only when it is in coverage (based on monitoring or prediction) and to pause the timer whenever the mobile device 3 moves out of coverage (or is predicted to be out of coverage). In this case, however, the mobile device 3 restarts the timer as soon as it (re)enters idle mode (from out of coverage). Effectively, this approach keeps the mobile device 3 in RRC idle mode longer, delaying PSM activation.

[0055] In the case of an NTN, there may be a relatively large number of UEs 3 with similar in-coverage windows. Therefore, if multiple UEs 3 enter the coverage of an NTN cell at substantially the same time, they may trigger (delay) uplink data and / or TAU transmissions at substantially the same time, which may cause excessive load on the network and data loss. To avoid such excessive load and data loss, the UEs 3 may be configured to use an appropriate backoff timer when entering coverage (after expiration of the associated second PSM timer). In other words, a mobile device with such a backoff timer configured delays initiating a transition to RRC connected mode and / or transmitting uplink data / TAU signaling until the backoff timer expires. This backoff value may be a PSM-specific backoff value, an NTN-specific backoff value, an eMTC / IoT-specific backoff value, and / or a TAU-specific backoff value, as appropriate, and may be transmitted to the UEs 3 via broadcast or dedicated signaling. The backoff timer may be different for each UE to allow for load balancing over time. A specific back-off timer value may be configured for each UE 3 by the network (e.g., base station 6 / core network node 9). Alternatively, the back-off timer value may be randomly derived (e.g., selected between "0" and a maximum back-off timer value configured by the network). If no such back-off timer is configured by the network (or is set to "0"), the mobile device 3 may transmit any uplink data / TAU signaling as soon as it enters coverage.

[0056] When a compatible mobile device 3 is configured for eDRX, the mobile device 3 monitors for paging opportunities only during a specific paging transmission window (PTW). In this system, the PTW is configured based on information provided by the network, such as information identifying the starting point of the PTW, a PTW offset, and / or a Hyper-System Frame Number (H-SFN) pair and a System Frame Number (SFN) value associated with the PTW. This approach may be beneficial when the mobile device 3 receives service over the NTN portion of the network, but may be applicable to other UEs as well.

[0057] To facilitate configuration of an appropriate PTW for the mobile device 3, the mobile device 3 may transmit appropriate assistance information to the network (e.g., core network node 9) that can be used to configure the PTW for the mobile device 3. The assistance information may identify a recommended or preferred PTW starting point (e.g., H-SFN, SFN pair), a recommended or preferred PTW length, any in-coverage time predictions, and / or a current or predicted UE location.

[0058] Beneficially, this approach allows the PTW to match / adapt to the coverage window of the mobile device 3 even if the mobile device 3 is moving and the mobile device 3 is out of coverage for a relatively long amount / portion of time.

[0059] <User Equipment (UE)> FIG. 2 is a block diagram illustrating the main components of the mobile device (UE) 3 shown in FIG. 1. As shown, the UE 3 includes transceiver circuitry 31 operable to transmit signals to and receive signals from connected nodes via one or more antennas 33. While not necessarily shown in FIG. 2, the UE 3 will, of course, have all the usual functionality of a conventional mobile device (such as a user interface 35 and a universal subscriber identity module (USIM) 36), which may be provided by any one or any combination of hardware, software, and firmware, as appropriate. A controller 37 controls the operation of the UE 3 in accordance with software stored in memory 39. The software may be pre-installed in memory 39 and / or downloaded via the communications network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 41, a communications control module 43, and a positioning module 45 (optional for some UEs).

[0060] The communications control module 43 is responsible for processing (generating / sending / receiving) signaling messages and uplink / downlink data packets between the UE 3 and other nodes, including NTN nodes 5, (R)AN nodes 6, and core network nodes. The signaling may include control signaling related to power saving mode operation or DRX / eDRX operation of the UE 3. If the UE 3 is configured to operate in eMTC / IoT / NB-IoT / IoT-NTN mode, the operation of the communications control module 43 is adapted accordingly.

[0061] If present, the positioning module 45 is responsible for determining the location of the UE 3, for example based on Global Navigation Satellite System (GNSS) signals.

[0062] <Access network nodes (base stations / gateways) and NTN nodes> FIG. 3 is a block diagram illustrating the main components of the access network node 6 (e.g., a base station (gNB) or gateway) shown in FIG. 1. FIG. 3 is also applicable to an NTN node 5 (a satellite or UAS platform). As shown, the access network node 6 / NTN node 5 includes transceiver circuitry 51 operable to transmit signals to and receive signals from connected UEs 3 via one or more antennas 53, and also to transmit signals to and receive signals from other network nodes (directly or indirectly) via a network interface 55. Signals may be transmitted to and received from the UEs 3 directly and / or via one or more NTN nodes 5, as appropriate. The network interface 55 typically includes an appropriate base station-to-base station interface (e.g., X2 / Xn) and an appropriate base station-to-core network interface (e.g., S1 / NG-C / NG-U), although some of these may be optional for an NTN node 5. A controller 57 controls the operation of the access network node 6 / NTN node 5 according to software stored in memory 59. The software may be pre-installed in memory 59 and / or downloaded via communication network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 61 and a communication control module 63.

[0063] The communication control module 63 is responsible for handling (generating / sending / receiving) signaling between the access network node 6 / NTN node 5 and other nodes such as the UE 3, other NTN nodes 5 / base stations 6, and core network nodes 9 (e.g. MME). The signaling may include control signaling related to power save mode operation or DRX / eDRX operation of the UE 3.

[0064] <Core network node> FIG. 4 is a block diagram illustrating the main components of the core network node 9 shown in FIG. 1, such as the MME and AMF. As shown, the core network node 9 includes a transceiver circuit 71 operable to transmit and receive signals (directly or indirectly) to and from other network nodes via a network interface 75. The network interface 75 typically includes an appropriate core network-base station interface (S1 / NG-C / NG-U, etc.). A controller 77 controls the operation of the core network node 9 in accordance with software stored in a memory 79. The software may be pre-installed in the memory 79 and / or downloaded via the communication network 1 or from a removable data storage device (RMD). The software includes, among other things, an operating system 81 and a communication control module 83.

[0065] The communication control module 83 is responsible for handling (generating / sending / receiving) signaling between the core network node 9 and the UE 3, access network nodes, and other core network nodes. The signaling may include control signaling related to power save mode operation or DRX / eDRX operation of the UE 3.

[0066] <Detailed explanation> Below is a description of some exemplary procedures (called Solutions 1 to 3) performed by the nodes of the system shown in FIG.

[0067] <Solution 1> PSM may be configured in compatible UEs 3 in Radio Resource Control (RRC) connected mode. In particular, PSM may be beneficial for eMTC / NB-IoT devices served by the NTN part of the network, although other types of UEs may also be configured to use PSM if desired.

[0068] As generally shown in the procedure designated "P1" in Figure 6, the network (in this case, the core network node 9) configures PSM for the UE 3 by providing values ​​for two timers associated with power saving mode operation (applicable to that mobile device 3). The network / core network node 9 can instruct the UE 3 to turn off PSM operation if the UE 3 does not provide values ​​for these timers, as generally shown in the procedure designated "P2".

[0069] When provided to the UE 3, the first timer ("T3324") controls how long the UE 3 remains in RRC idle mode before activating a PSM. The second timer ("T3412") controls how often the UE 3 needs to perform periodic tracking area updates (TAUs), unless the UE 3 moves to another tracking area. In effect, the second timer controls the maximum length of activation of each power saving mode, because upon expiration of the second timer, the UE 3 needs to enter RRC connected mode to send a TAU message (to inform the network / core network node about the current location of the mobile device 3). The UE 3 may cancel the PSM and enter RRC connected mode for reasons other than TAU signaling, such as if it has uplink data to send (which cannot be delayed).

[0070] Now, referring to Figures 7 to 9, when UE3 enters RRC idle mode, it starts a first timer (T3324) and starts monitoring whether UE3 is in coverage or out of coverage in order to control (start and end) power saving mode operation.

[0071] There are three ways to activate PSM depending on the coverage situation of the UE:

[0072] As shown in Figure 7, if UE3 remains in coverage while the timer is running, UE3 activates PSM upon expiration of the timer. In another case, shown in Figure 8, UE3 activates PSM if it moves out of coverage while the first timer is running. The third case (shown in Figure 9) is similar to the first case. However, in this case, UE3 does not take into account the period spent out of coverage of the first timer. As can be seen, whenever UE3 loses coverage, it pauses the first timer (T3324) and only resumes it when UE3 actually goes into RRC idle mode (returns to coverage).

[0073] To facilitate determining whether a UE 3 is in-coverage or out-of-coverage at a particular time and / or location, the network may provide satellite information to the UE 3 via broadcast information or dedicated signaling (e.g., access stratum or non-access stratum signaling). Based on such satellite information and the UE location (if available), the UE 3 can predict or estimate a future in-coverage window and control the timer accordingly. Furthermore, the mobile device 3 can suspend monitoring whether the mobile device 3 is in-coverage or out-of-coverage until the predicted in-coverage window to conserve battery.

[0074] In either case, the UE 3 remains in the PSM at least until the second timer (T3412) expires or until uplink data arrives (including TAU signaling if the UE 3 has moved to a new tracking area). However, in one possibility shown in FIG. 8, UE3 may remain in the PSM until it determines (based on monitoring) that it is back in coverage or is expected (based on prediction) to be back in coverage, upon expiration of the second timer (T3412) or upon arrival of uplink data.

[0075] In a particularly useful option, the cancellation / deactivation of PSM is based on a back-off timer, which can be started (later) upon expiry of a second timer or upon entering network coverage. Such a back-off timer reduces or distributes the network load caused by a relatively large number of UEs 3 with similar coverage windows and similar timing of their respective (delayed) uplink data and / or TAU transmissions upon entering the coverage of an NTN cell.

[0076] More specifically, the UEs 3 may be configured to start an appropriate back-off timer upon entering coverage (after expiration of the associated second PSM timer). The back-off timer causes each UE 3 to delay transmitting uplink data / TAU signaling until the back-off timer expires. The back-off timer may also delay the UE 3 from transitioning to RRC connected mode, effectively extending the time spent in PSM.

[0077] The back-off value may be transmitted to the UE 3 via broadcast or dedicated signaling. The back-off timer may be different for each UE. This may be achieved by configuring a specific back-off timer value for each UE 3. Alternatively, the value of the back-off timer may be randomly derived (e.g., chosen between "0" and the maximum back-off timer value set by the network).

[0078] Below are descriptions of some example scenarios related to Figures 8 and 9, with the following assumptions: -UE3 is within the satellite's coverage from 8:00 (8:00 AM) to 12:00 (12:00 PM) every 24 hours. UE3 is configured with timers T3324 and T3412 (PSM time = T3412 - T3324). -T3324=15 minutes. -T3412=100 days.

[0079] Using the above assumptions, if UE 3 is experiencing discontinuous coverage (as in Figures 8 or 9), UE 3 needs to check whether there is network coverage when it needs to transmit uplink data or TAUs. In other words, when UE 3 wakes up from PSM (because it has uplink data or TAUs to send), it first needs to check whether there is actually network coverage at this time. This may be based on predictions based on satellite ephemeris data, UE location information, etc.

[0080] 1) The UE wants to wake up at 10:00 AM to transmit uplink data. If UE3 wants to wake up from PSM because it has uplink data / TAUs to send, it can predict that it has network coverage (because the current time is between 8:00 and 12:00). Therefore, rather than immediately waking up from PSM to initiate an RRC procedure / Scheduling Request (SR) to send uplink data, UE3 checks whether it can expect network coverage at this time. If UE3 determines that it has (or predicts to have) network coverage, it wakes up (releases PSM), synchronizes with the network, and transmits the uplink data / SR. The data transmission causes UE3 to transition to connected mode and then back to idle mode. Once in idle mode again, UE3 starts timer T3324 (which runs for 15 minutes) before transitioning back to power saving mode.

[0081] 2) The UE wants to wake up at 11:55 AM to transmit uplink data. In this scenario, UE3 also does not immediately initiate an RRC procedure / SR to send uplink data, but first checks whether it can expect network coverage at this time. At 11:55 AM, UE3 can predict that it has network coverage. Therefore, UE3 wakes up (releases PSM), synchronizes with the network, and sends uplink data / SR.

[0082] In this case, the UE's behavior will differ depending on whether it follows the approach shown in Figure 8 or the approach shown in Figure 9. In the case of Figure 8, UE3 returns to idle mode around 11:56 AM and starts timer T3324, which runs for 15 minutes, or until 12:11 PM. However, because UE3 is out of coverage, it transitions to power save mode at 12:00 PM.

[0083] As in the alternative example shown in FIG. 9, UE3 may be configured to stop / suspend the timer as soon as UE3 goes out of coverage and resume the timer when UE3 returns to coverage. Thus, when UE3 enters idle mode again at 11:56 AM, UE3 starts the T3324 timer (for a total of 15 minutes). However, in this case, the timer only runs for 4 minutes until 12:00, when the timer is paused because UE3 is out of coverage. The timer remains paused until 8:00 AM, when UE3 comes back into coverage, at which point the timer is resumed (11 minutes remaining in this example). As can be seen, UE3 only enters PSM at 8:11 AM (the expiry of the T3324 timer). Thus, while UE3 is not in PSM while it is out of coverage, it does not waste power (even though it has uplink data to transmit). This is because the UE 3 can determine the expected time when it will be back in coverage and delay data transmission accordingly.

[0084] 3) The UE wants to wake up at 13:00 (1:00 PM) to transmit uplink data. Instead of immediately waking up from PSM to initiate an RRC procedure / SR to transmit uplink data, UE3 checks and determines that it does not have (or is not expected to have) network coverage at this time. Therefore, UE3 remains in power save mode and begins buffering data until UE3 is again in coverage. At 8:00 AM, UE3 again enters network coverage, wakes up from PSM, and transmits the data (optionally with a backoff value) that was buffered while it was in network coverage. In this scenario, the same behavior occurs in both Figures 8 and 9.

[0085] <Solution 2> When a compatible mobile device 3 is configured with eDRX, the mobile device 3 monitors paging occasions only during a specific paging transmission window (PTW). As generally shown in Figure 10, different UEs 3 (in this case, "UEx" and "UEy") can be configured to use their own network-assigned PTWs. The overall procedure is shown in Figure 11, and the overall procedure is based on existing eDRX-based paging procedures.

[0086] However, in this case, the network (core network node 9) provides information of the PTW appropriate for the particular UE 3. Specifically, such UE-specific PTW information may include information identifying the start of the PTW for that UE 3, a PTW offset, and / or the Hyper-System Frame Number (H-SFN) and System Frame Number (SFN) pair associated with the PTW. The core network node 9 may transmit this information to the UE 3 in an appropriate NAS message (see step S2), such as an Attach Accept message or a Tracking Area Update Accept message. In this case, the UE-specific information may be included in a so-called "Extended DRX parameter" information element (or other appropriate information element), in addition to other information elements such as the PTW length and eDRX cycle length (which may be common for all UEs).

[0087] The UE 3 stores this information, determines the assigned PTW, and monitors for paging occasions only during the appropriate paging transmission window.

[0088] The UE-specific PTW information may also be included in paging messages from the core network node 9 to the base station 6 to help the base station 6 page each UE 3 at the appropriate time (see step S6). In this case, the UE-specific information may be included in addition to the PTW length / eDRX cycle length in a so-called "Paging eDRX Information" information element (or any other suitable information element).

[0089] To facilitate configuration of an appropriate PTW for the mobile device 3, the mobile device 3 may transmit appropriate assistance information to the network (e.g., core network node 9) that can be used to configure the PTW for the mobile device 3. The assistance information may identify a recommended or preferred PTW starting point (e.g., H-SFN, SFN pair), a recommended or preferred PTW length, any in-coverage time predictions, and / or a current or predicted UE location.

[0090] It will be appreciated that the UE 3 may be configured to use appropriate TAU and / or NAS signaling to provide updates of eDRX assistance information to the core network node 9. For example, the UE 3 may indicate whether the configured eDRX is not (or no longer is) consistent with its in-coverage window, or indicate that the UE's location has changed (e.g. beyond a relevant threshold or distance from a reference point) such that an update of the paging window is required. A TAU / NAS message may contain one or more of the following: -eDRX support information (extended paging cycle, PTW length and location). - Information about the location of the UE (e.g. location updates). - Information about the UE mobility state (e.g., high, low, or stationary mobility).

[0091] <Solution 3> In existing systems, the PTW is specific to a UE and is determined by the paging hyperframe (PH), the start position (PTW_start) within the PH, and the end position (PTW_end). The values ​​of PH, PTW_start, and PTW_end are calculated using the following formula: PH is an H-SFN that satisfies the following formula: H-SFN mod T eDRX,H = (UE_ID_H mod T eDRX,H ) where UE_ID_H is an identifier associated with UE 3 (UE_ID_H will be either the most significant 10 or 12 bits of the UE's hash ID depending on the channel used for paging). T eDRX,H is the number of hyperframes (T eDRX,H = 1, 2, ..., 256 hyperframes).

[0092] The parameter PTW_start is part of the PTW and indicates the first radio frame of the PH having an SFN that satisfies the following equation: SFN = 256*i eDRX where: i eDRX = floor(UE_ID_H / T eDRX,H ) mod 4 The parameter PTW_end indicates the last radio frame of the PTW and has an SFN that satisfies the following formula: SFN = (PTW_start+L*100-1) mod 1024 where L = length of paging time window (in seconds) set by higher layers.

[0093] In this system, to provide an appropriate PTW for a UE3 that is expected to be out of coverage for some time (while being served by the NTN portion of the network), the values ​​of PH, PTW_start, and PTW_end are re-defined using the following approach:

[0094] 1. The lower layers of the UE 3 (and the lower layers of the base station 6) may be configured to discard POs outside the coverage window of the UE. If the paging window partially overlaps with the coverage window, only the part within the coverage window is retained for paging transmission. In other words, only paging occasions (or parts thereof) that are within the coverage window of the UE are used.

[0095] 2. If the paging windows of different UEs need to be evenly distributed across the timeline, an example can remain proportional to the in-coverage periods after discarding the out-of-coverage periods.

[0096] 3. UE IDs in the same satellite service area may share the same coverage window (due to satellite movement). If the system frame number (i.e., SFN) is counted continuously only within the coverage window, the resulting paging window for each UE will also fall within its respective coverage window.

[0097] Assume that a cell's operating time (with a granularity of 10 ms) is available to the UE 3 and the network. In this case, the term operating time refers to the total time (within a 24-hour period) that a particular UE can be served by that cell. Of course, operating times can be location-specific, although common operating time values ​​can be applied if desired.

[0098] Based on the applicable operating time, the actual system frame number and hyper system frame number available to a particular UE3 are denoted by SFN and H-SFN, respectively, using the following approach: SFN and H-SFN only count the coverage period / cell operating time, stop incrementing if they are (partially) outside the coverage window, and resume incrementing continuously in the next coverage window. -SFN wraps around every 1024. When the -SFN wraps around, the H-SFN is incremented by one. -When H-SFN wraps around, H-SFN also wraps around.

[0099] The network calculates the values ​​of SFN and H-SFN (or the values ​​deltaSFN=SFN-SFN and deltaH-SFN=H-SFN-HSFN) and broadcasts these values ​​to UE3 in the system information. If UE3 can obtain information about the cell operation time, UE3 can derive the values ​​of SFN and H-SFN on its own. Advantageously, UE3 can derive the applicable values ​​of PH, PTW_start, and PTW_end using the same formulas but using SFN instead of SFN and H-SFN instead of H-SFN.

[0100] Therefore, in this system, the PH of the UE is the H-SFN that satisfies the following equation: H-SFN mod T eDRX,H =(UE_ID_H mod T eDRX,H ) where UE_ID_H is the identifier associated with UE3 (10 or 12 most significant bits), T eDRX,H is the number of hyperframes (T eDRX,H = 1, 2, ..., 256 hyperframes).

[0101] The parameter PTW_start is part of the PTW and indicates the first radio frame of the PH having an SFN that satisfies the following equation: SFN=256*i eDRX where: i eDRX =floor(UE_ID_H / T eDRX,H ) mod 4 The parameter PTW_end indicates the last radio frame of the PTW within the coverage window and has an SFN that satisfies the following equation: SFN=(PTW_start+L*100-1) mod 1024 where L = length of paging time window (in seconds) set by higher layers.

[0102] It will be appreciated that UE3 (and base station 6) may be configured to switch between an SFN-using formula and an SFN-using formula depending on whether UE3 is served by an NTN cell and / or the availability of cell operating time information. For example, UE 3 may be configured to initially determine its PTW based on a formula that uses SFN, and then switch to a formula that uses SFN when it goes out of coverage (for the first time).

[0103] Advantageously, if the relevant PTW is derived based on the SFN instead of the SFN, the network can avoid paging the UE 3, and the UE 3 does not need to monitor for paging messages during periods when the UE 3 is out of coverage (or when the UE's cell is not operational).

[0104] <Fixes and alternatives> Detailed embodiments have been described above. As will be appreciated by those skilled in the art, many modifications and alternatives can be made to the above embodiments while still enjoying the benefits of the invention embodied therein. By way of example, some of these alternatives and modifications are now described.

[0105] It will be understood that base stations in 5G / NR communication systems are commonly referred to as New Radio Base Stations ("NR-BS") or "gNBs," and that these may also be referred to using the term "eNB" (or 5G / NR eNB), which is more commonly associated with Long Term Evolution (LTE) base stations (also commonly referred to as "4G" base stations). The term base station may refer to any of the following nodes as defined in 3GPP Technical Specifications 38.300 (V16.6.0) and 37.340 (V16.6.0):

[0106] gNB: A node that provides NR user plane and control plane protocol termination for the UE and is connected to the 5G Core Network (5GC) via the NG interface.

[0107] ng-eNB: A node that provides Evolved Universal Terrestrial Radio Access (E-UTRA) user plane and control plane protocol termination to the UE and is connected to the 5GC via the NG interface.

[0108] En-gNB: A node that provides NR user plane and control plane protocol termination for the UE and acts as a secondary node for E-UTRA-NR dual connectivity (EN-DC).

[0109] NG-RAN node: A node that is either a gNB or ng-eNB.

[0110] It will be understood that the above embodiments are applicable to both the 5G new radio system and the LTE system (E-UTRAN). A base station (gateway) supporting the E-UTRA / 4G protocol may be referred to as an "eNB," and a base station supporting the Next Generation / 5G protocol may be referred to as a "gNB." It will be understood that some base stations may be configured to support both the 4G protocol and the 5G protocol, and / or other 3GPP or non-3GPP communication protocols.

[0111] Table 1 - Types of Satellites and UAS Platforms [Table 1]

[0112] It will be appreciated that there are various architectural options for implementing an NTN in a 4G system, some of which are illustrated schematically in FIG. 12. The first option shown is an NTN featuring an access network based on satellites / antennas with bent pipe payloads and terrestrial eNBs (at the satellite hub or gateway level) serving UEs. The second option is an NTN featuring an access network based on satellites / antennas with eNBs serving UEs. The third option is an NTN featuring an access network based on satellites / antennas with bent pipe payloads serving relay nodes. The fourth option is an NTN featuring an access network based on satellites / antennas with eNBs serving relay nodes. It will be appreciated that other architectural options, such as a combination of two or more of the above-mentioned options, can also be used. Alternatively, the relay node may comprise a satellite / UAS. It will be appreciated that similar architectural options can be used in a 5G / NR system as well, but with a gNB instead of an eNB and an NGC instead of an EPC.

[0113] For ease of understanding, the above description has been presented with the UE, NTN node (satellite / UAS platform), and access network node (base station) as having a number of separate modules (e.g., communications control module). While these modules may be provided in this manner for certain applications, such as when an existing system is modified to implement the present invention, and for other applications, such as systems designed from the beginning with the features of the present invention in mind, these modules may not be recognizable as separate entities because they may be incorporated into the overall operating system or code. These modules may also be implemented in software, hardware, firmware, or a combination thereof.

[0114] Each controller may comprise any suitable form of processing circuitry including, but not limited to, for example, one or more hardware-implemented computer processors, microprocessors, central processing units (CPUs), arithmetic logic units (ALUs), input / output (IO) circuitry, internal memory / cache (program and / or data), processing registers, communication buses (such as a control bus, data bus, address bus), direct memory access (DMA) functions, hardware or software implemented counters, pointers, and / or timers, and / or the like.

[0115] In the above embodiments, a number of software modules have been described. As will be appreciated by those skilled in the art, the software modules may be provided in compiled or uncompiled form and may be provided to the UE, NTN node, and access network node (base station) as signals via a computer network or a recording medium. Furthermore, the functions performed by some or all of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred because they facilitate updates to update the functionality of the UE, NTN node, and access network node (base station).

[0116] The above embodiments are also applicable to "non-mobile" or generally fixed user equipment.

[0117] The method performed by the UE may further include pausing the timer when the UE moves out of coverage while the timer is running.

[0118] The method performed by the UE may further include restarting the paused timer when the UE moves into coverage and enters RRC idle mode.

[0119] The method performed by the UE may further include activating the power saving mode upon expiration of a timer.

[0120] The method performed by the UE may further include deactivating the power saving mode when the UE moves in-coverage. For example, the UE may deactivate the power saving mode when moving in-coverage and when the UE needs to initiate mobile-originated data transmission or signaling (such as a tracking area update).

[0121] The method performed by the UE may further include, after deactivating the power saving mode, entering an RRC connected mode and initiating data transmission if the UE has data to transmit. In this case, the method may further include delaying the transmission after moving in coverage (e.g., based on an associated backoff value). The transmission may include a tracking area update (TAU).

[0122] The method performed by the UE may further include determining whether the UE is in-coverage or out-of-coverage based on at least one of information about nodes of the non-terrestrial network (such as satellite ephemeris information), information about the location of the UE (e.g., Global Navigation Satellite System (GNSS) signaling), and monitoring wireless signals.

[0123] The method performed by the UE may further comprise receiving, using at least one information element in a Non-Access Stratum (NAS) message (e.g., an “Attach Accepted” message, a “TAU Accepted” message, or a “Paging” message), information identifying a paging transmission window. The information identifying the paging transmission window may identify at least one of a start of the paging transmission window, a PTW offset, and a pair of Hyper-System Frame Number (H-SFN) and System Frame Number (SFN) values.

[0124] The method performed by the UE may include transmitting the assistance information using at least one information element (e.g., using a Tracking Area Update (TAU) and / or Non-Access Stratum (NAS) signaling). The assistance information may identify at least one of a recommended or preferred PTW starting point (e.g., H-SFN, SFN pair), a recommended or suggested PTW length, a predicted in-coverage time, and a current or predicted UE location.

[0125] The method performed by the UE may include transmitting assistance information to a network node if the UE's current PTW does not match its in-coverage window and / or if the UE's location has changed (e.g., exceeding an associated threshold or distance from a reference point).

[0126] The method performed by the UE may include entering a radio resource control (RRC) connected mode to initiate data transmission upon expiration of a back-off timer. The method performed by the UE may include receiving information for determining a value of the back-off timer via broadcast or dedicated signaling. The information for determining the value of the back-off timer may identify either a specific value of the back-off timer and a maximum value of the back-off timer to be used in selecting a random value of the back-off timer.

[0127] Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

[0128] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above embodiments.

[0129] Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the disclosure.

[0130] The program can be stored and provided to a computer device using any type of non-transitory computer-readable medium. Non-transitory computer-readable media include any type of tangible storage medium. Examples of non-transitory computer-readable media include magnetic storage media (such as floppy disks, magnetic tapes, and hard disk drives), magneto-optical storage media (such as magneto-optical disks), CD-ROMs (read-only memories), CD-Rs, CD-R / Ws, and semiconductor memories (such as mask ROMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, and random access memories (RAMs)). The program can be provided to a computer device using any type of non-transitory computer-readable medium. Examples of non-transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The non-transitory computer-readable medium can provide the program to a computer device via wired communication lines such as electric wires and optical fibers, or wireless communication lines.

[0131] For example, all or part of the embodiments disclosed above can be described as follows, but are not limited to these. (Appendix 1) 1. A method for a User Equipment (UE) for communicating over a non-terrestrial network, comprising: determining whether the UE is within coverage of the non-terrestrial network or is out of coverage of the non-terrestrial network; initiating a power saving procedure for the UE based on the determination; and A method for a UE comprising: (Appendix 2) receiving satellite information in a system information block; the determination is based on the satellite information; The method described in Appendix 1. (Appendix 3) The power saving procedure is a procedure for entering a power saving mode of the UE. 1. The method according to claim 1 or 2. (Appendix 4) maintaining the power saving mode until the UE is within coverage of the non-terrestrial network. The method described in Appendix 3. (Appendix 5) and estimating a next reception coverage window of the non-terrestrial network based on information transmitted from the non-terrestrial network. The method described in Appendix 4. (Appendix 6) receiving information identifying a value of a timer associated with the power saving mode; Entering Radio Resource Control (RRC) idle mode; starting the timer upon entering the RRC idle mode; Furthermore, when the UE moves out of coverage of the non-terrestrial network while the timer is running based on the value; or If the UE remains within the coverage of the non-terrestrial network while the timer is running based on the value, when the timer expires according to the value, entering the power saving mode is performed. 6. The method of any one of appendices 3 to 5. (Appendix 7) and pausing the timer if the UE moves out of coverage of the non-terrestrial network while the timer is running based on the value. The method described in Appendix 6. (Appendix 8) restarting the timer when the UE moves into coverage of the non-terrestrial network and enters the RRC idle mode. The method described in Appendix 7. (Appendix 9) and canceling the power saving mode when the UE moves into coverage. 9. The method of any one of appendices 3 to 8. (Appendix 10) and, after exiting the power saving mode, if the UE has data to transmit, entering an RRC connected mode to start data transmission. The method described in Appendix 9. (Appendix 11) delaying the data transmission after moving into coverage. 11. The method described in Appendix 10. (Appendix 12) information about nodes of the non-terrestrial network; information regarding the location of the UE; and Monitoring radio signals; The determination is made based on at least one of the following: 12. The method of any one of appendices 1 to 11. (Appendix 13) the power saving procedure is a procedure for discarding at least one paging occasion outside a period in which the UE is in coverage. 1. The method according to claim 1 or 2. (Appendix 14) the discarding is performed such that a paging window of each of the UEs remains proportional to a respective coverage window of each of the UEs. The method described in Appendix 13. (Appendix 15) performing an enhanced Discontinuous Reception (eDRX) operation based on a Paging Transmission Window (PTW); The PTW is determined by stopping the increase of at least one of a Hyper-System Frame Number (H-SFN) and a System Frame Number (SFN) when the PTW is outside the coverage window of the UE. 15. The method of claim 13 or 14. (Appendix 16) receiving information identifying a location of the PTW associated with the UE for the eDRX operation; performing the eDRX operation based on the information; and Further provided with The method described in Appendix 15. (Appendix 17) the information being included in at least one information element in a Non-Access Stratum (NAS) message; The method described in Appendix 16. (Appendix 18) The information is the start point of the PTW; PTW offset, and a pair of values ​​for the Hyper-System Frame Number (H-SFN) and the System Frame Number (SFN); Identifying at least one of 18. The method of claim 16 or 17. (Appendix 19) The power saving procedure is a procedure for transmitting assistance information to a network node to be used in configuring a paging transmission window (PTW) of the UE for enhanced discontinuous reception (eDRX) operation. 1. The method according to claim 1 or 2. (Appendix 20) The support information is included in at least one information element. 19. The method described in Appendix 19. (Appendix 21) The support information is a recommended or preferred PTW starting point for said PTW; Recommended or preferred PTW length, Predicting in-coverage time, and the current or predicted location of the UE; Identifying at least one of 21. The method of claim 19 or 20. (Appendix 22) The transmission is performed if the UE's current PTW does not match its coverage window and / or if the UE's location has changed. 22. The method of any one of appendices 19 to 21. (Appendix 23) the power saving procedure is a procedure for starting a back-off timer transmitted from the non-terrestrial network when the mobile station enters coverage of the non-terrestrial network; The method further comprises commencing data transmission upon expiration of the backoff timer. 1. The method according to claim 1 or 2. (Appendix 24) and, upon expiration of the back-off timer, entering a Radio Resource Control (RRC) connected mode to initiate the data transmission. 24. The method described in Appendix 23. (Appendix 25) a particular value of the back-off timer; and a maximum back-off timer used in selecting the random value of the back-off timer; receiving information identifying one of the 25. The method of claim 23 or 24. (Appendix 26) The information is transmitted via broadcast or dedicated signaling. The method described in Appendix 24. (Appendix 27) 1. A method of a network node for communicating with User Equipment (UE) over a non-terrestrial network, comprising: transmitting information to the UE for controlling power saving based on a determination of whether the UE is in-coverage or out-of-coverage based on the value, and initiating the power saving procedure of the UE based on the determination. Network node method. (Appendix 28) the information includes a timer value; The power saving procedure is a procedure for entering a power saving mode of the UE, when the UE moves out of coverage of the non-terrestrial network while the timer is running based on the value; or If the UE remains within the coverage of the non-terrestrial network while the timer is running based on the value, when the timer expires according to the value, entering the power saving mode is performed. 27. The method described in Appendix 27. (Appendix 29) the power saving procedure is a procedure for discarding at least one paging occasion outside a period in which the UE is in coverage; The information includes information indicating a Paging Transmission Window (PTW) position associated with the UE for enhanced Discontinuous Reception (eDRX) operation; At least one of a Hyper-System Frame Number (H-SFN) and a System Frame Number (SFN), which is outside the coverage window of the UE, is skipped at the PTW position, and the method includes: performing the eDRX operation based on the information indicating the PTW position. 27. The method described in Appendix 27. (Appendix 30) the power saving procedure is a procedure for discarding at least one paging occasion outside a period in which the UE is in coverage; The information includes information indicating a Paging Transmission Window (PTW) position associated with the UE for enhanced Discontinuous Reception (eDRX) operation; If at least one of a Hyper-System Frame Number (H-SFN) and a System Frame Number (SFN) is outside the coverage window of the UE, the PTW position is skipped, and the method includes: receiving the information indicating the PTW location in a paging message; paging the UE based on the information indicating the PTW location; Further provided with 27. The method described in Appendix 27. (Appendix 31) the power saving procedure is a procedure for starting a back-off timer transmitted from the non-terrestrial network when the mobile station enters coverage of the non-terrestrial network; When the backoff timer expires, the UE starts data transmission. 27. The method described in Appendix 27. (Appendix 32) 1. A user equipment (UE) for communicating over a non-terrestrial network, comprising: means for determining whether the UE is within coverage of the non-terrestrial network or is out of coverage of the non-terrestrial network; means for initiating a power saving procedure for the UE based on the determination; A UE equipped with: (Appendix 33) The power saving procedure is a procedure for entering a power saving mode of the UE, and the UE further means for receiving information identifying a value of a timer associated with said power saving mode; means for entering a Radio Resource Control (RRC) idle mode; means for starting the timer upon entering the RRC idle mode; Equipped with when the UE moves out of coverage of the non-terrestrial network while the timer is running based on the value; or If the UE remains within the coverage of the non-terrestrial network while the timer is running based on the value, when the timer expires according to the value, entering the power saving mode is performed. UE as described in Appendix 32. (Appendix 34) The power saving procedure is a procedure for discarding at least one paging occasion outside a period in which the UE is in coverage, and the UE: means for receiving information indicating a Paging Transmission Window (PTW) position associated with the UE for enhanced Discontinuous Reception (eDRX) operation; and means for performing the eDRX operation based on the information; The PTW is determined by stopping the increase of at least one of a Hyper-System Frame Number (H-SFN) and a System Frame Number (SFN) when the PTW is outside the coverage window of the UE. 32. The method described in Appendix 32. (Appendix 35) The power saving procedure is a procedure for transmitting assistance information to a network node to be used in configuring a paging transmission window (PTW) of the UE for enhanced discontinuous reception (eDRX) operation. UE as described in Appendix 32. (Appendix 36) The power saving procedure is a procedure for starting a back-off timer transmitted from the non-terrestrial network when the UE enters a coverage area of ​​the non-terrestrial network, and the UE means for initiating data transmission upon expiration of the back-off timer; UE as described in Appendix 32. (Appendix 37) 1. A network node for communicating with User Equipment (UE) over a non-terrestrial network, comprising: and means for transmitting information to the UE for controlling power saving based on a determination of whether the UE is in-coverage or out-of-coverage based on the value, and initiating the power saving procedure of the UE based on the determination. Network node. (Appendix 38) the information includes a timer value; The power saving procedure is a procedure for entering a power saving mode of the UE, when the UE moves out of coverage of the non-terrestrial network while the timer is running based on the value; or If the UE remains within the coverage of the non-terrestrial network while the timer is running based on the value, when the timer expires according to the value, entering the power saving mode is performed. 38. The network node of claim 37. (Appendix 39) the power saving procedure is a procedure for discarding at least one paging occasion outside a period in which the UE is in coverage; The information includes information indicating a Paging Transmission Window (PTW) position associated with the UE for enhanced Discontinuous Reception (eDRX) operation; At least one of a Hyper-System Frame Number (H-SFN) and a System Frame Number (SFN), which is outside the coverage window of the UE, is skipped at the PTW position, and the network node: means for performing the eDRX operation based on the information indicating the PTW position. 38. The network node of claim 37. (Appendix 40) the power saving procedure is a procedure for discarding at least one paging occasion outside a period in which the UE is in coverage; The information includes information indicating a Paging Transmission Window (PTW) position associated with the UE for enhanced Discontinuous Reception (eDRX) operation; If at least one of a Hyper-System Frame Number (H-SFN) and a System Frame Number (SFN) is outside the coverage window of the UE, the PTW position is skipped, and the network node: means for receiving the information indicating the PTW location in a paging message; means for paging the UE based on the information indicating the PTW location; Further provided with 38. The network node of claim 37. (Appendix 41) the power saving procedure is a procedure for starting a back-off timer transmitted from the non-terrestrial network when the mobile station enters coverage of the non-terrestrial network; When the backoff timer expires, the UE starts data transmission. 38. The network node of claim 37.

[0132] This application claims the benefit of priority to UK Patent Application No. 2111281.8, filed August 4, 2021, the entire disclosure of which is incorporated herein by reference. [Explanation of symbols]

[0133] 1. Communication Systems 3 User Equipment (UE) 5 satellites 6 Gateway 7. Data Network 9 Mobility Management Entity (MME) 31, 51, 71 Transceiver circuits 33, 53 antenna 35 User Interface 55, 75 network interface 36 USIM 37, 57, 77 Controller 39, 59, 79 memory 41, 61, 81 Operating Systems 43, 63, 83 Communication control module 45 Positioning Module

Claims

1. A mobile device, means for determining whether the mobile device is in or out of coverage of a non-terrestrial network; means for transmitting, to a network node, assistance information for setting an unavailability period of the non-terrestrial network due to a loss of coverage of the non-terrestrial network based on the determination; A mobile device comprising:

2. the assistance information includes information indicating a period corresponding to coverage of the non-terrestrial network; The mobile device of claim 1 .

3. The assistance information is transmitted in a Non-Access Stratum (NAS) message.

3. The mobile device according to claim 1 or 2.

4. means for receiving, from said network node, information indicative of a timer value specific to said non-terrestrial network; means for controlling data communication using said timer value; 3. The mobile device according to claim 1 or 2, comprising:

5. means for transmitting a message in response to the expiration of the timer value; The mobile device according to claim 4 .

6. a network node, means for receiving, from a mobile device, assistance information for setting a non-terrestrial network unavailability period due to loss of coverage of the non-terrestrial network based on a determination of whether the mobile device is in or out of coverage of the non-terrestrial network; a means for setting a period during which the non-terrestrial network is unavailable based on the support information; A network node comprising:

7. 1. A method in a mobile device, comprising: determining whether the mobile device is in or out of coverage of a non-terrestrial network; sending, to a network node, assistance information for setting an unavailability period of the non-terrestrial network due to a loss of coverage of the non-terrestrial network based on the determination; A method in a mobile device, comprising:

8. 1. A method in a network node, comprising: receiving, from the mobile device, assistance information for setting a non-terrestrial network unavailability period due to loss of coverage of the non-terrestrial network based on a determination of whether the mobile device is in or out of coverage of the non-terrestrial network; setting a period during which the non-terrestrial network is unavailable based on the support information; and 10. A method in a network node, comprising:

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