Managing discontinuous coverage and power saving modes in NTN using distance thresholds

Abstract

A user equipment, UE, (102) connected to a core network (110) via a non-terrestrial network, NTN, while in a first location receives (1402) a distance threshold (1402) before the UE enters a power saving mode, PSM. While in the PSM, the UE initiates (1406) a procedure for reporting current UE location information when the current UE location has exceeded a distance threshold relative to the first location.

Description

Technical Field

[0001] The present disclosure relates generally to methods, apparatus, and articles of manufacture in wireless communication systems, such as 3GPP communication systems. Background Art

[0002] This background description is provided for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors, to the extent that it is described in this background section, and aspects of the specification that otherwise may not be considered prior art at the time of filing, are neither explicitly nor implicitly admitted to be prior art to the present disclosure.

[0003] The goals behind developing fifth-generation (5G) technology include providing a unified framework for communication types such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC).

[0004] 5G technology mainly relies on the old terrestrial network. However, the Third Generation Partnership Project (3GPP) organization has proposed to extend 5G communications to non-terrestrial networks (NTN) using 5G New Radio (NR) technology or using Long Term Evolution (LTE) technology customized for narrowband Internet of Things (NB-IoT) or enhanced machine type communication (eMTC) scenarios. In NTN, radio frequency RF transceivers are installed on satellites, unmanned aerial vehicle systems (UAS) (also known as drones, balloons, airplanes), or other suitable devices. For simplicity, the following discussion refers to all such devices as satellites. In addition to satellites, NTNs may also include satellites or NTN gateways (satellite gateways) that connect non-terrestrial networks to public data networks, feeder links between satellite gateways and satellites, service links between satellites, and inter-satellite links (ISLs) when satellites form a constellation.

[0005] Satellites may belong to one of several types based on altitude, orbit, and beam footprint size. The types include low earth orbit (LEO) satellites, medium earth orbit (MEO) satellites, geostationary orbit (GEO) satellites, UAS platforms (including high altitude platform stations (HAPS)), and highly elliptical orbit (HEO) satellites. GEO satellites are also known as geosynchronous orbit (GSO) satellites, and LEO / MEO satellites are also known as non-GSO (NGSO) satellites.

[0006] GSO satellites can communicate with one or several satellite gateways deployed over the satellite's target coverage area (e.g., a geographic area or even a continent). Non-GSO satellites can communicate with one or several serving satellite gateways at different times. NTN is designed to ensure service and feeder link continuity between successive serving satellite gateways, with sufficient duration for mobile anchoring and handover.

[0007] Satellites can support transparent or regenerative (with onboard processing) payloads and typically generate several beams for a given service area defined by the field of view. The coverage area of ​​the beam typically has an elliptical shape and depends on the onboard antenna configuration and elevation angle. For transparent payload implementations, the satellite can apply RF filtering as well as frequency conversion and amplification without changing the waveform signal. For regenerative payload implementations, the satellite can apply RF filtering, frequency conversion and amplification, demodulation and decoding, routing, and encoding / modulation. This approach is actually equivalent to implementing most of the functions of a base station (e.g., gNB).

[0008] NB-IoT and eMTC technologies are expected to be particularly useful for IoT devices operating in remote areas with limited or no terrestrial connectivity. Such IoT devices can be used in a variety of industries, including, for example, transportation (marine, road, rail, aviation) and logistics; solar energy, oil and gas extraction; utilities; agriculture; environmental monitoring; and mining. However, to ensure the required IoT connectivity, the deployment of these technologies requires satellite connectivity to provide coverage beyond terrestrial deployments. Satellite NB-IoT or eMTC is defined in a complementary manner to terrestrial deployments.

[0009] In these and other applications, the UE may experience discontinuous coverage in time, as well as coverage only occasionally. Moreover, because UEs in such applications typically have limited power, the UE may operate in a power saving mode (PSM) for hours or days without a radio resource control (RRC) protocol relationship between the UE and the network. The UE may then wake up in short periods of time to notify the network of its presence and perform DL / UL transmissions for buffered communications accumulated during the PSM. Therefore, when the time periods when the UE wakes up are not well aligned with the time periods of NTN coverage, the UE may miss relatively infrequent opportunities to communicate with the network, and thus cause the network to prematurely log off or disconnect the UE. Summary of the invention

[0010] In general, the techniques of the present disclosure allow UEs to more efficiently utilize power saving mode (PSM). In PSM, the UE has no connectivity with the network according to the protocol for controlling radio resources. The UE and the network use these techniques to align UE activity times with periods of satellite coverage in order to reduce the probability of the network prematurely deregistering or disconnecting the UE. In addition, these techniques improve the accuracy of UE location information stored at the network by triggering the UE to report its location information when the UE travels beyond a given distance.

[0011] An example embodiment provides a method for initiating a process for reporting location information, which is implemented in a UE and includes: when in a first position, receiving a distance threshold from a base station connected to a core network by one or more processors; and in response to determining that the current UE position has exceeded the distance threshold relative to the first position, initiating a process for reporting the current UE location information to the core network.

[0012] In some example embodiments, determining that the distance threshold has been exceeded includes determining that the UE has traveled at least the distance threshold from a first location in a cell of the base station. Additionally, in some example embodiments, the method further includes, prior to receiving the distance threshold, transmitting, by the one or more processors to the base station, an indication of the current location of the UE.

[0013] Additionally, in some example embodiments, initiating a process for reporting current location information of the UE after the UE has exceeded the distance threshold includes transmitting, by one or more processors, a Tracking Area Update (TAU) request message to the core network. In some example embodiments, the method further includes receiving, by one or more processors, a TAU accept message including a new distance threshold in response to the TAU request message. Moreover, in some example embodiments, the method further includes delaying transmission of the TAU request until the UE has entered a coverage area of ​​a radio access network (RAN) connected to the core network.

[0014] Furthermore, in some example embodiments, the determining occurs when the UE is operating in a power saving mode (PSM).

[0015] Additionally, in some example embodiments, the base station is associated with a non-terrestrial network (NTN).

[0016] Yet another example embodiment of the techniques is a UE including one or more processors and configured to implement the above methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a block diagram of an example wireless communication system in which user devices and base stations of the present disclosure may implement the location updating and power saving techniques of the present disclosure;

[0018] Figure 2 The centralized unit (CU) and the distributed unit (DU) can be Figure 1 A block diagram of an example base station operating in the system of A;

[0019] Figure 3A is a block diagram of an example NTN node with a transparent payload implementation;

[0020] Figure 3B is a block diagram of an example NTN node with a transparent payload implementation in which a base station is connected to multiple satellites via the same satellite gateway;

[0021] Figure 4A Shown is the supply Figure 3A An exemplary user plane protocol stack for use with an architecture of

[0022] Figure 4B Shown with Figure 3A An exemplary control plane protocol stack for use with an architecture;

[0023] Figure 5 shows an example configuration according to which a UE implements enhanced discontinuous reception (eDRX);

[0024] Figure 6 shows an example configuration according to which a UE implements a power saving mode (PSM);

[0025] Figure 7 An example scenario is shown where the UE has satellite coverage during certain time periods separated by non-coverage intervals;

[0026] Fig. 8A shows an example scenario in which the network deregisters a UE operating in PSM due to misalignment between UE activity time and satellite coverage;

[0027] Figure 8B An example scenario is shown in which a UE operating in PSM remains active even after leaving an area of ​​satellite coverage;

[0028] Fig.9A and Fig. 9B is a messaging diagram for an example scenario in which the UE provides the network with latest location information during an Attach or Tracking Area Update procedure for aligning the PSM configuration with the period of satellite coverage;

[0029] Fig.10is a messaging diagram for an example scenario in which the UE has the capability to estimate satellite coverage to align the PSM configuration with the period of satellite coverage, and provides suggested timer values ​​to the network in the Attach or Tracking Area Update procedure;

[0030] Fig.11 and Fig.12 is a flow chart of an example method for determining how to apply a PSM configuration and when to perform a TAU in a PSM, the example method being implemented by a user equipment capable of obtaining its location information;

[0031] Fig.13A and Fig. 13B is a flow chart of an example method for determining how to apply a PSM configuration and when to perform a TAU in a PSM, which example method may be implemented by a user equipment capable of estimating / predicting satellite coverage of the present disclosure;

[0032] Fig.14 is a flow chart of an example method for initiating a process for reporting location information, which example method may be implemented in a UE of the present disclosure; and

[0033] Fig.15 is a flow chart of an example method for configuring a UE to report location information, which example method may be implemented in a network device of the present disclosure. DETAILED DESCRIPTION

[0034] As discussed in more detail below, a user equipment (UE) and / or a network node of a radio access network (RAN) may use the techniques of this disclosure to manage early data communications and to transition the UE between states of a protocol for controlling radio resources between the UE and the RAN.

[0035] First reference Figure 1 , the example wireless communication system 100 includes a UE 102, a base station (BS) 104, a base station 106, and a core network (CN) 110. The base stations 104 and 106 may operate in a RAN 105 connected to the core network (CN) 110 and other base station components such as a satellite, as will be described with reference to Figure 3A and Figure 3B CN 110 may be implemented as, for example, an evolved packet core (EPC) 111 or a fifth generation (5G) core (5GC) 160. CN 110 may also be implemented as a sixth generation (6G) core and future evolutions.

[0036] Base station 104 covers cell 124, and base station 106 covers cell 126. If base station 104 is a gNB, cell 124 is an NR cell. If base station 104 is an ng-eNB or an eNB, cell 124 is an Evolved Universal Terrestrial Radio Access (E-UTRA) cell. Similarly, if base station 106 is a gNB, cell 126 is an NR cell, and if base station 106 is an ng-eNB or an eNB, cell 126 is an E-UTRA cell. Cells 124 and 126 may be located in the same radio access network notification area (RNA) or in different RNAs. In general, RAN 105 may include any number of ground base stations and non-ground base stations, and each of the base stations may cover one, two, three, or any other suitable number of cells. UE 102 may support at least 5G NR (or simply "NR") or E-UTRA air interface to communicate with base stations 104 and 106. Each of the base stations 104, 106 may be connected to the CN 110 via an interface (eg, an S1 or NG interface). The base stations 104 and 106 may also be interconnected via an interface for interconnecting NG RAN nodes (eg, an X2 or Xn interface).

[0037] Among other components, the EPC 111 may include a serving gateway (SGW) 112, a mobility management entity (MME) 114, and a packet data network gateway (PGW) 116. In general, the SGW 112 is configured to transmit user plane packets related to audio calls, video calls, Internet traffic, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides connectivity from the UE to one or more external packet data networks (e.g., an Internet network and / or an Internet Protocol (IP) Multimedia Subsystem (IMS) network). The 5GC 160 includes a user plane function (UPF) 162 and an access and mobility management function (AMF) 164 and / or a session management function (SMF) 166. Generally speaking, UPF 162 is configured to pass user plane packets associated with audio calls, video calls, Internet traffic, etc., AMF 164 is configured to manage authentication, registration, paging and other related functions, and SMF 166 is configured to manage PDU sessions.

[0038] like Figure 1 As shown, base station 104 supports cell 124, and base station 106 supports cell 126. Cells 124 and 126 may partially overlap, such that UE 102 may select, reselect, or switch from one of cells 124 and 126 to the other. Satellite base stations may provide additional RAN 105 coverage, as shown in FIG. Figure 7In order to directly exchange messages or information, base station 104 and base station 106 may support an X2 or Xn interface. In general, CN 110 may be connected to any suitable number of ground base stations and non-ground base stations that support NR cells and / or EUTRA cells.

[0039] As discussed in detail below, the UE 102 and / or RAN 105 can utilize the techniques of the present disclosure when the radio connection between the UE 102 and the RAN 105 is suspended, for example, when the UE 102 operates in an inactive or idle state of a protocol for controlling radio resources between the UE 102 and the RAN 105. For clarity, the following examples refer to the RRC_INACTIVE or RRC_IDLE states of the RRC protocol. The UE 102 can further utilize the techniques of the present disclosure when the radio connection between the UE 102 and the RAN 105 is disconnected and operates in PSM where there is no radio resource control (RRC) protocol relationship between the UE and the network.

[0040] The base station 104 is equipped with processing hardware 130, which may include one or more general-purpose processors (e.g., CPUs) and non-transitory computer-readable memory storing instructions executed by the one or more general-purpose processors. In addition or alternatively, the processing hardware 130 may include a dedicated processing unit. In an example implementation, the processing hardware 130 includes a processor 132 to process data to be transmitted by the base station 104 in the downlink direction, or to process data received by the base station 104 in the uplink direction. The processing hardware 130 may also include a transmitter 136, which is configured to transmit data in the downlink direction. The processing hardware may further include a receiver 134, which is configured to receive data in the uplink direction. The base station 106 may include substantially similar components. The core network 110 includes at least one network device 140 having components 142, 144, and 146 that are similar to components 132, 134, and 136, respectively.

[0041] UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors such as CPUs, and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors, and / or a dedicated processing unit. In an example implementation, the processing hardware 150 includes a processor 152 to process data to be transmitted by UE 102 in the uplink direction, or to process data received by UE 102 in the downlink direction. The processing hardware 150 may also include a transmitter 156 configured to transmit data in the downlink direction. The processing hardware may also include a receiver 154 configured to receive data in the uplink direction.

[0042] In some embodiments, the RAN 105 supports integrated access and backhaul (IAB) functionality. In some implementations, the DU 174 operates as an IAB node and the CU 172 operates as an IAB donor. In some embodiments, the RAN 105 supports non-terrestrial network (NTN) functionality.

[0043] Figure 2 An example distributed or decentralized implementation of any of the base stations 104, 106 is depicted. In this implementation, the base station 204 includes a central unit (CU) 172 and a distributed unit (DU) 174 (but the base station may include more than one DU). The CU 172 includes processing hardware such as one or more general-purpose processors (e.g., CPUs) and a computer-readable memory storing machine-readable instructions that can be executed on the general-purpose processors, and / or a dedicated processing unit. For example, the CU 172 may include a PDCP controller, an RRC controller, and / or an RRC inactivity controller. In some implementations, the CU 172 may include a radio link control (RLC) controller that is configured to manage or control one or more RLC operations or processes. In other implementations, the CU 172 does not include an RLC controller.

[0044] Similarly, DU 174 also includes processing hardware such as one or more general purpose processors (e.g., CPUs) and computer readable memory storing machine readable instructions executable on one or more general purpose processors, and / or dedicated processing units. For example, the processing hardware may include: a MAC controller configured to manage or control one or more MAC operations or processes (e.g., random access processes); and / or an RLC controller configured to manage or control one or more RLC operations or processes. The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or processes.

[0045] In some implementations, the CU 172 may include a logical node CU-CP 172A that hosts a control plane portion of a PDCP protocol of the CU 172. The CU 172 may also include a logical node CU-UP 172B that hosts a user plane portion of a PDCP protocol and / or a Service Data Adaptation Protocol (SDAP) protocol of the CU 172. The CU-CP 172A may transmit control information (e.g., RRC messages, F1 application protocol messages), and the CU-UP 172B may transmit data packets (e.g., SDAP PDUs or Internet Protocol packets).

[0046] CU-CP 172A may be connected to multiple CU-UPs 172B via an E1 interface. CU-CP 172A selects an appropriate CU-UP 172B for the requested service of UE 102. In some implementations, a single CU-UP 172B may be connected to multiple CU-CPs 172A via an E1 interface. CU-CP 172A may be connected to one or more DUs 174 via an F1-C interface. CU-UP 172B may be connected to one or more DUs 174 via an F1-U interface under the control of the same CU-CP 172A. In some implementations, one DU 174 may be connected to multiple CU-UPs 172B under the control of the same CU-CP 172A. In such implementations, connectivity between CU-UP 172B and DU 174 is established by CU-CP 172A using a bearer context management function.

[0047] Figure 3A A certain type of NTN deployment, referred to as a transparent payload architecture, is shown, involving a satellite gateway 302 and a "transparent" satellite 304 for extending the range of the Uu interface. The NTN deployment may be incorporated as an extension of another base station or BS 104 (or BS 106). Figure 1 The satellite 304 implements frequency conversion and radio frequency (RF) amplifiers in both the uplink and downlink directions. The satellite function is similar to that of an analog RF repeater. Therefore, the satellite 304 relays the Uu radio interface from the feeder link (between the NTN gateway and the satellite) to the service link (between the satellite and the UE) in the downlink direction, and vice versa in the uplink direction. The satellite radio interface (SRI) on the feeder link is Uu, and the NTN gateway 302 supports all functions necessary to forward the signals of the Uu interface. The NTN gateway 302 can be placed at the same site as the base station (e.g., eNB, gNB) 104, or connected to the base station 104 at a certain distance via a wired link. More than one NTN gateway can also be connected to the base station. Different transparent satellites can be connected to the same base station on the ground via the same NTN gateway or via different NTN gateways. Figure 3B A situation is shown where two different satellites (304 and 306) are connected to the same base station 104 via the same NTN gateway 302 and the two satellites (304 and 306) cover the earth's surface using two different physical cell IDs (PCIs).

[0048] exist Figure 4AFIG. 1 shows an NTN user plane protocol stack involving UE 102, satellite 304, NTN gateway 302, BS 104 and EPC S-GW 112 (or 5G CSMF 166). The diagram of the NTN user plane protocol stack is similar to FIG. Figure 2 A is a diagram of a terrestrial network (TN) with the addition of two new nodes placed in the middle of the Uu interface, namely the satellite 304 and the NTN gateway 302. Similarly, Figure 4B The NTN control plane protocol stack shown in is also similar to Figure 2 The protocol stack of the terrestrial network counterpart is shown in B.

[0049] In terms of satellite mobility patterns, there are three types of service links supported in NTN: ● Geofixed: configured by a beam that always continuously covers the same geographical area (e.g. the case of GEO / GSO satellites) ● Quasi-geo-fixed: configured by beams that cover one geographical area during a limited period of time and a different geographical area during another period of time (e.g. the case of LEO / MEO satellites that can use steerable beams) • Geomobile: A beam configuration whereby its coverage area slides above the Earth's surface (eg, the case of LEO / MEO satellites using fixed or unsteerable beams).

[0050] Using LEO / MEO satellites, eNB can provide quasi-Earth fixed cell coverage or Earth mobile cell coverage. Using GEO satellites, eNB can provide Earth fixed cell coverage.

[0051] although Figure 3A / Figure 3B The transparent payload architecture shown is the current focus of 3GPP development, but a regenerative payload architecture that places some of the BS functionality on the satellite is also a possible future NTN deployment. In such an architecture, the Uu exists only between the satellite and the UE. For example, the satellite can implement Figure 2 The functionality of DU 174. In general, the techniques of the present disclosure may be applied to transparent payload architectures as well as regenerative payload architectures.

[0052] Extended discontinuous reception (eDRX) is an extension of the DRX feature used by IoT or MTC devices to further reduce power consumption when the UE is in RRC_IDLE mode. Using the DRX mechanism, the user device can enter sleep mode in RRC_IDLE mode for a specific period of time, and then wake up after the sleep period to monitor DL ​​signals from the base station. The DRX cycle defines the time interval between two consecutive time periods when the UE wakes up. eDRX enhancement will extend the DRX cycle to allow the device to remain in sleep mode for a longer period of time. Relative to DRX mode, eDRX enhancement can be used to achieve additional power savings.

[0053] In one example, an LTE device is configured with a paging cycle (i.e., DRX cycle) of up to 2.56 seconds. With this configuration, the UE wakes up every 2.56 seconds during the paging opportunity (PO) in the paging frame (PF) and monitors for paging from the network. On the other hand, an LTE device supporting eDRX can be configured with an eDRX cycle of up to 2621.44 seconds, which allows the device to wake up once every 2621.44 seconds for a paging time window (PTW). Therefore, LTE devices supporting the eDRX feature can consume much less power than devices that do not support this feature. In addition, NB-IoT devices (which support eDRX by default) can be configured with an eDRX cycle of up to 10485.76 seconds, which allows the device to wake up once every 2.9 hours, and therefore, NB-IoT devices can save even more power than LTE devices supporting eDRX. Devices supporting the eDRX feature do not need to wake up for the entire PTW (ranging from 1.28 seconds to 20.48 seconds), but only wake up at the paging occasions within the PTW determined by the legacy DRX configuration / parameters.

[0054] The UE and the network (e.g., MME or AMF) negotiate DRX and eDRX parameters using the following messages: Attach Request, Attach Accept, Tracking Area Update Request, and Tracking Area Update Accept. During the attach process, the UE provides preferred values ​​for DRX and eDRX parameters in the Attach Request message, and the network provides the final values ​​of these parameters in the Attach Accept message. The UE may transmit an Attach Complete message to the network in response to the Attach Accept message. Similarly, during the Tracking Area Update (TAU) process, the preferred values ​​for DRX and eDRX parameters are provided by the UE in the Tracking Area Update Request message, and the final values ​​of these parameters are provided by the network in the Tracking Area Update Accept message. The UE may transmit a TAU Complete message to the network in response to the TAU Accept message. In the case of DRX configuration for non-NB-IoT devices, the network will only accept or reject the preferred DRX configuration set by the UE in the Attach Request / Tracking Area Update Request, and will not provide the revised configuration in the Attach Accept / Tracking Area Update Accept message.

[0055] The DRX cycle length may be configured using the following example values: {320ms, 640ms, 1280ms, 2560ms}. For NB-IoT devices, the PTW length can be configured from the following values: {2.56s, 5.12s, 7.68s, 10.24s, 12.8s,15.36s, 17.92s, 20.48s, 23.04s, 25.6s, 28.16s, 30.72s, 33.28s, 35.84s, 38.4s,40.96s} and the eDRX cycle length can be configured from the following values: {5.12s, 10.24s, 20.48s, 40.96s,61.44s, 81.92s, 102.4s, 122.88s, 143.36s, 163.84s, 327.68s, It should be noted that if the eDRX cycle length is configured as 5.12s, the UE will not have a PTW, and the UE will only perform the legacy DRX operation in which the DRX cycle length is equal to 5.12s.

[0056] Figure 5 An example is shown in which a UE is configured with an eDRX cycle equal to 20.48 seconds, a PTW equal to 5.12 seconds, and a DRX cycle equal to 1.28 seconds. In this example, the UE is configured to wake up 4 times (one paging occasion (PO) each) during the PTW in order to monitor paging messages. In addition to the PTW, the UE can completely shut down its radio module for about 15.36 seconds per eDRX cycle and thus save a lot of power.

[0057] Power saving mode (PSM) generally reduces (sometimes significantly) the power consumption of IoT devices. UEs that support PSM have more control over power management that is appropriate for their applications, which can be very advantageous because there is a wide range of IoT applications. PSM mode is generally similar to a power outage, but the UE remains registered to the network while in PSM. Although the UE remains registered to the network during PSM, the UE does not have a radio resource control (RRC) protocol relationship with the network during PSM. Similar to the eDRX mechanism, the UE controls PSM using two timers configured through the Attach or TAU process. The first timer is T3324, which defines the time period during which the UE must remain in idle mode (and monitor paging) when transitioning from RRC_CONNECTED to RRC_IDLE. The second timer is an extended T3412 timer, which controls the periodicity (i.e., time interval) at which the UE performs periodic TAUs.

[0058] The UE may first include a T3324 value in an Attach Request message or a TAU Request message, and then the network (e.g., MME 114 or AMF 164 in another implementation) may respond to the UE with a confirmed T3324 value in an Attach Accept message or a TAU Accept message. When transitioning from a CONNECTED state to an IDLE state, the UE starts a timer T3324. When the T3324 timer expires, the UE transitions to a power saving mode. The T3324 timer defines a time period during which the device remains reachable for a mobile terminated (MT) event when transitioning from a connected state to an idle state. When the network receives T3324 in an Attach Request or in a TAU Request message, the network considers its local configuration when determining the final T3324 value. In some implementations, if the T3324 value is not included in the Attach Request or TAU Request message, the MME does not include the T3324 value in the Attach Accept or TAU Accept message. When T3324 is still running, UEs supporting the PSM feature can be used for paging. In some implementations, the network may configure T3324 with a value of "0" in the Attach Accept message or the TAU Accept message. In such implementations, the UE enters power saving mode immediately after transitioning to the RRC_IDLE state. T3324 values ​​range from 0 to 31, and the time unit is one of the following: {2 seconds, 1 minute, one tenth of an hour}.

[0059] Because T3324 is a timer running on the UE, the network starts a counterpart timer (called an "activity timer") upon determining that the UE has transitioned from CONNECTED to IDLE state. The activity timer has the same value as T3324. While the activity timer is still running, the network assumes that the UE is still available for paging and accordingly pages the UE upon detecting any pending MT events. When the activity timer expires, the network assumes that the UE has transitioned to PSM and therefore paging messaging directed to the UE may be suspended even when there are pending MT events.

[0060] The T3412 timer is also called a periodic TAU timer. The UE performs a periodic TAU when the T3412 timer expires to periodically notify the network of the UE's availability. The UE may first include a T3412 value during the Attach or TAU process, and then the network responds to the UE with the T3412 value in the Attach Accept or Tracking Area Update Accept message. When the UE operates in all tracking areas assigned to the UE, the UE applies this value until the UE receives a new value. When transitioning to the IDLE state, the UE starts the timer T3412, and when determining that the UE has transitioned to the IDLE state, the network (e.g., MME 114, or AMF 164 in another implementation) also starts the counterpart timer "Mobile Reachable Timer". The Mobile Reachable Timer has a dependency on the T3412 timer and is 4 minutes longer than the T3412 timer by default. When the network and the UE establish a NAS connection, the network stops the Mobile Reachable Timer. When the Mobile Reachable Timer expires, the network starts another timer called the "Implicit Disconnect Timer". If the implicit detach timer expires before the UE contacts the network, the network implicitly detaches from the UE.

[0061] To support the PSM feature, the UE must be configured with a longer version of T3412 using the T3412 Extended Value IE. If the UE indicates support for extended periodic timer values ​​in the Attach Request or TAU Request message (e.g., via a standardized mobile station MS, network feature support information element IE), the network may also include the T3412 Extended Value IE in the Attach Accept or TAU Accept message. In addition to the T3412 extended value recommended by the UE, the network considers local configuration when determining the final value of the T3412 extended value. If the network includes the T3412 Extended Value IE in the Attach Accept or TAU Accept message, the UE uses the value indicated in the T3412 Extended Value IE as the value of the timer T3412. The T3412 Extended Value IE contains values ​​ranging from 0 to 31, where the time unit is selected from the following set: {10 minutes, 1 hour, 10 hours, 2 seconds, 30 seconds, 1 minute, 320 hours}.

[0062] Figure 6An example is shown in which the UE is configured with a T3324 timer equal to 10 minutes and a T3412 timer equal to 1 hour. In this example, the UE performs a periodic TAU every 1 hour and remains in the connected state for the duration defined by the inactivity timer after performing the TAU. After the inactivity timer expires, the UE transitions to the IDLE state and monitors for paging for the duration defined by the T3324 timer, which is 10 minutes in this example. At the expiration of the T3324 timer, the device enters PSM and begins to consume almost no power. The device wakes up again at the expiration of T3412 to transition to RRC_IDLE and then performs a TAU in RRC_CONNECTED mode.

[0063] Table 1 below shows the UE timers and network timers related to the PSM feature, and the corresponding actions performed by the UE / network when these timers expire:

[0064] Figure 7 An example scenario is shown in which a LEO satellite 304 (whose position is shown at different times t1, t2, t3, t4) serves a UE (such as, for example, UE 102) between t1 and t2, and another LEO satellite 306 306 (whose position is also shown at different times t1, t2, t3, t4) serves the UE between t3 and t4. During the time period between t2 and t3, UE 102 is not served by any satellite or any ground base station and is therefore out of coverage. Typically, when a UE loses coverage of a serving cell, the UE begins searching for other cells and then camps on a suitable cell. However, in the Figure 7 In the example shown in , even if UE 102 starts searching for other cells immediately after t2, the UE cannot find the cell, and thus searching for other cells causes the UE to only expend power. Figure 7 To optimize power consumption at the UE in a specific NTN scenario of the scenario depicted in , the UE may not be required to perform a cell search, and the UE may deactivate the access stratum (AS) functionality during the period when the UE is not within the coverage area of ​​the satellite. However, doing so would require the UE to know when the UE will be outside the coverage area, and when the UE will be within the coverage area again, in order to reactivate its cell search or AS functionality before the UE falls into the coverage of another NTN cell. Note that Figure 7 There is no assumption that UE 102 is stationary.

[0065] Fig. 8AAn example scenario is shown in which a UE receives a PSM configuration that is not aligned with satellite coverage. In this example, the UE initially operates in RRC_CONNECTED state 802A and receives a PSM configuration that includes a T3412 value and a T3324 value. Upon receiving an RRC Connection Release message or at Figure 6 10A, 10B, 10C, 10B, 10A, 10B ... In this example, due to discontinuous satellite coverage, the UE cannot contact the network within a short time after the expiration of the mobile reachable timer (e.g., approximately 4 minutes after the expiration of T3412 at the UE), and therefore the network determines to disconnect the UE at t4. Later at t5, the UE detects that it is within satellite coverage 814A and initiates a radio resource control RRC connection establishment procedure to send a TAU request to the network. However, since the network has disconnected the UE at t4 and the UE is unaware of this event, the UE unsuccessfully expends power at t5 in an attempt to perform a TAU procedure 808A with the network.

[0066] Figure 8BAnother example is shown in which the UE receives a PSM configuration that is not aligned with satellite coverage. In this example, the UE initially operates in the RRC_CONNECTED state 802B and receives a PSM configuration including a T3412 value and a T3324 value. The UE transitions to the IDLE state 804B and initiates T3412 and T3324 at t1, and then further enters PSM 806B at t2 when T3324 expires. In this example, the UE is able to perform a TAU 808B and contact the network at t3, which occurs after T3412 expires and before the network disconnects the UE because the UE is within satellite coverage 814B at t3. However, since the UE is not within satellite coverage 814B during the entire time that timer T3324 runs, the network can attempt to reach the UE by sending one or more paging messages to the UE after t4, which will most likely fail to reach the UE. Such paging messages unnecessarily consume radio resources and otherwise burden the network. In this example, the UE may also need to wake up for an additional duration after t4, which consumes power of the UE unnecessarily. In addition, because the UE will remain in the CONNECTED state (e.g., 802B, 808B) for a duration that depends on the actual traffic situation (i.e., the duration is unpredictable), it is difficult for the network to configure and the UE to recommend an appropriate T3324 value that aligns the total UE active time with satellite coverage.

[0067] Additionally, in order to configure the UE with PSM aligned with the occurrence of satellite coverage, the network may need to obtain UE positioning / location information before determining the configuration. However, obtaining location information from the UE when the UE is in PSM is challenging because the network has no control over the UE, and therefore, the present disclosure proposes that the UE should trigger a location report.

[0068] Fig.9A900 is a message passing diagram of an example scenario in which a UE provides its latest location information to the network in an Attach or Tracking Area Update procedure for aligning a PSM configuration with a period of satellite coverage. Although the BSs 104, 106 are shown as eNB radio access technology satellites, the BSs 104, 106 may be implemented as any type of satellite 304, 306 compliant with 4G, 5G, 6G or future standards. The UE 102 is initially connected to the eNB 104 via a serving link provided by the satellite 304 and operates in an RRC_CONNECTED state 901. Initially, the UE 102 transmits 902 a NAS message such as an ATTACH REQUEST or TAU REQUEST message to the eNB 104, which then encapsulates the ATTACH REQUEST or TAU REQUEST message in an S1-AP message (i.e., a control plane message between the RAN and the core, such as an Initial UE message) and forwards it 904 to the MME 114. When sending the ATTACH REQUEST or TAU REQUEST message, the UE 102 may indicate that it supports extended periodic timer values ​​(e.g., via the MS Network Feature Support IE) and include the T3324 value and the T3412 Extended Value IE in the message. The UE 102 also provides its location information (e.g., its GNSS coordinates) in the ATTACH REQUEST or TAU REQUEST message. After receiving the ATTACH REQUEST or TAU REQUEST message, the MME 114 determines / calculates the period during which the UE 102 will be covered by at least one NTN cell and the period during which the UE 102 will not be covered by any NTN cell based on the satellite ephemeris information (i.e., satellite constellation information) pre-provided to the MME 114 or pre-installed in the MME, the UE location information given by the UE 102 during the ATTACH or TAU process, and some other auxiliary information (such as cell / beam coverage area size and / or antenna panel tilt). The MME 114 then determines a PSM configuration for the UE 102 that matches the period of satellite coverage determined / calculated by the MME 114 .

[0069] In response to the ATTACH REQUEST or TAU REQUEST message, the MME 114 encapsulates the ATTACH ACCEPT or TAU ACCEPT message in an initial UE message and sends it 906 to the eNB 104, which then forwards 908 the ATTACH ACCEPT or TAU ACCEPT message to the UE 102. The MME 114 provides the determined PSM configuration of the UE 102 that matches the period of satellite coverage in the ATTACH ACCEPT or TAU ACCEPT message. In one implementation, the determined PSM configuration includes a T3412 extension value IE and a UE activity timer for determining when the UE 102 should transition to PSM. The UE transitions to PSM when the UE activity timer expires, which starts immediately when the UE receives the PSM configuration from the network. Because the UE behavior with respect to the UE activity timer is generally similar to the behavior of T3324, for the remainder of this disclosure, the UE activity timer may be referred to as T3324'.

[0070] In one implementation, the MME 114 may include the original T3324 value IE in the PSM configuration, rather than including an IE specifically defined to convey the T3324' value. In one implementation, in addition to the PSM configuration, the MME 114 also provides a distance threshold in the ATTACHACCEPT or TAU ACCEPT message, which the UE uses to determine whether it needs to perform a TAU based on the distance it has traveled. As an alternative to the above implementation, the above-mentioned distance threshold is broadcasted by the eNB 104 in the system information.

[0071] After receiving the ATTACH ACCEPT or TAU ACCEPT message, the UE 102 starts 909 a timer T3324'. Upon expiration of T3324', the UE 102 then enters 910 PSM and starts a timer T3412. In some implementations, the UE 102 also starts an inactivity timer after receiving the ATTACH ACCEPT or TAU ACCEPT message, and in response to the expiration of the inactivity timer, the UE 102 then transitions to the RRC_IDLE state before transitioning to the PSM. In other implementations, after receiving the ATTACH ACCEPT or TAU ACCEPT message, the UE also receives an RRC connection release message from the eNB 104 via the satellite 304, and in response to the RRC connection release message, transitions to the RRC_IDLE state before transitioning to the PSM. If the UE 102 transitions to the RRC_IDLE state before transitioning to the PSM, the UE 102 starts T3412 when transitioning to the RRC_IDLE state instead of when transitioning in the PSM.

[0072] At a later time, the UE 102 operating under PSM is no longer within the service area of ​​the satellite 304 because the satellite 304 has moved 912 to a new location such that the satellite 304 cannot provide coverage to the UE 102. Thereafter, the UE 102 detects 914 that it has traveled a distance greater than a distance threshold provided by the MME 114 or by the eNB 104. Even later, when the UE 102 detects that the satellite 306 has begun 916 serving the area (i.e., has begun covering the UE 102), the UE 102 performs an RRC connection establishment procedure with the eNB 106 and transmits 918 a TAU REQUEST message to the eNB 106 to inform the MME 114 of the updated UE location. The UE 102 includes its location information (e.g., its GNSS coordinates) in the TAU REQUEST message, and may also include the T3324 value and T3412 extension value IEs.

[0073] The eNB 106 forwards 920 the TAU REQUEST message from the UE 102 to the MME 114, and then receives 922 a TAU ACCEPT message from the MME 114 in response to the TAU REQUEST message. The TAU ACCEPT message may include an updated T3324' value, an updated T3412 extension value, and an updated distance threshold, wherein the MME 114 determines these updated values ​​based on the updated UE location. The UE 102, upon receiving 924 the TAU ACCEPT message forwarded by the eNB 106, replaces the stored T3324' value and T3412 extension value with the new values ​​provided in the TAU ACCEPT message, and then starts 925 the timer T3324'. When T3324' expires, the UE transitions 926 to PSM and starts the timer T3412. In some cases, the UE 102 may transition to the RRC_IDLE state before transitioning to PSM. In these cases, UE 102 will start T3412 earlier than the time at which UE 102 transitions to RRC_IDLE state. Shortly after UE 102 transitions to PSM, satellite 306 moves 928 to a new location such that satellite 306 cannot cover UE 102.

[0074] After a relatively long period of time since the UE transitioned to PSM, timer T3412 expires 930. The UE 102 now needs to initiate a periodic TAU with the MME 114. The UE 102 in this scenario waits until an upcoming satellite (e.g., satellite 304 connected to the eNB 104) begins 932 serving the area where the UE 102 is currently located, and then the UE 102 transmits 934 a TAU REQUEST message to the MME 114 via the eNB 104. When sending the TAU REQUEST message, the UE 102 may indicate that it supports extended periodic timer values ​​(e.g., via the MS Network Feature Support IE), and include the T3324 value, the T3412 extended value, and the UE location in the message. The eNB 104 then forwards 936 the TAU REQUEST message to the MME 114. In response to the TAU REQUEST message, the MME 114 transmits 938 a TAU ACCEPT message to the UE 102 via the eNB 104, which may include an updated PSM configuration including an updated T3324' value and an updated T3412 extension value. The TAU ACCEPT message may also include an updated distance threshold used by the UE to check whether it needs to perform a TAU based on the distance it has traveled. The UE 102, upon receiving 940 the TAU ACCEPT message, replaces the stored T3324' value and T3412 extension value with the new values ​​included in the TAU ACCEPT message, and then starts 941 timer T3324'.

[0075] In one implementation, the MME 114 may transmit another instance of T3412 in the ATTACH ACCEPT or TAU ACCEPT message instead of the T3412 Extension Value IE. Upon receiving the ATTACH ACCEPT or TAU ACCEPT message containing this T3412 instance, the UE 102 immediately starts T3412 instead of starting this timer when the UE transitions to the RRC_IDLE state or enters PSM. In one implementation, this T3412 instance has the same value or the same value range as the T3412 Extension Value IE.

[0076] Fig. 9B950 is a message transfer diagram of another example scenario 950 in which the UE provides its latest location information to the network in the Attach or Tracking Area Update procedure for aligning the PSM configuration with the period of satellite coverage. This scenario is generally similar to scenario 900, but here the UE 102 only receives the distance threshold and does not utilize timer T3324' (the network does not utilize a counterpart timer either). The differences between scenarios 900 and 950 are discussed below.

[0077] A UE 102 operating 901 in connected mode transmits 903 a NAS message, such as an ATTACH REQUEST or TAU REQUEST message, to an MME 114 via an eNB 104, which includes UE location information. In some cases, the UE 102 also includes an indication that the UE 102 supports distance threshold checking. Using the location information, the MME 114 determines a distance threshold based on the factors discussed above and transmits 907 the distance threshold to the UE 102 in an ATTACH ACCEPT or TAU ACCEPT message. The UE 102 then uses the distance threshold to determine whether the UE 102 should perform a TAU in view of the distance traveled. When the UE 102 has traveled beyond the distance threshold, the UE wakes up from the PSM and transmits 917 a TAU REQUEST message, even if the T3412 timer has not expired. The T3412 timer may be extended or non-extended in this scenario.

[0078] UE 102 may then receive 923 a TAU ACCEPT message with a new distance threshold, which may be the same value or a different value than that provided in event 907. MME 114 may determine the new distance threshold in view of the updated current position and the new satellite ephemeris information of UE 102. Similarly, UE 102 transmits 935 a TAUREQUEST message to MME 114 and provides the current position information, and receives 941 the new distance threshold in response.

[0079] Next, Fig.10 A message passing diagram of an example scenario 1000 is shown in which the UE informs the network of its ability to estimate satellite coverage in an Attach or Tracking Area Update procedure to align the PSM configuration with the period of satellite coverage. Although the BSs 104, 106 are shown as eNB radio access technology satellites, the BSs 104, 106 may be implemented as any type of satellite 304, 306 compliant with 4G, 5G, 6G or future standards.

[0080] The UE 102 is initially connected to the eNB 104 via a serving link provided by the satellite 304 and operates in an RRC_CONNECTED state 1001. In this scenario, the UE 102 is able to estimate the period of time when the UE 102 will be within the coverage of at least one satellite and the period of time when the UE 102 will not be covered by any satellite based on satellite ephemeris information (i.e., satellite constellation information) pre-provided to the UE 102 or pre-installed in the UE 102, UE location information, and some other auxiliary information provided by the network (such as cell / beam coverage area size and / or antenna panel tilt). Initially, the UE 102 transmits 1002 a NAS message such as an ATTACH REQUEST or TAU REQUEST message to the eNB 104, and the eNB 104 then encapsulates the ATTACH REQUEST or TAU REQUEST message in an S1-AP message such as an initial UE message and forwards 1004 it to the MME 114. When sending an ATTACH REQUEST or TAU REQUEST message, the UE 102 may indicate in the message that it supports extended periodic timer values ​​(e.g., via an IMS Network Feature Support IE), and include a T3324 value and a T3412 extension value that the UE 102 selects so that the UE 102 will be active (for monitoring pages, performing TAUs, etc.) only during periods when the UE 102 is within coverage of at least one satellite. In one implementation, the UE 102 delivers calibrated T3324 and T3412 values ​​in the ATTACH REQUEST or TAU REQUEST message using a dedicated IE specifically defined to convey T3324' and / or T3412' rather than using an IE defined to convey T3324 and T3412 extension values.

[0081] As an alternative to the above implementation, the UE 102 may include a T3324 value IE and a T3412 extension value IE in an ATTACH REQUEST or TAU REQUEST message to deliver calibrated T3324 and T3412 values, and indicate to the MME 114 via an additional IE (e.g., a one-bit flag) that the UE has determined the T3324 and T3412 values ​​by estimating the period of satellite coverage (i.e., the T3324 and T3412 values ​​have been calibrated).

[0082] In response to the ATTACH REQUEST or TAU REQUEST message, the MME 114 encapsulates the ATTACH ACCEPT or TAU ACCEPT message in an initial UE message and sends 1006 it to the eNB 104. The eNB 104 then forwards 1008 the ATTACH ACCEPT or TAU ACCEPT message to the UE 102. The MME 114 provides the determined PSM configuration of the UE 102 in the ATTACH ACCEPT or TAU ACCEPT message. In one implementation, the determined PSM configuration includes a T3412 extension value that "echoes" the T3412 / T3412' extension value contained in the ATTACH REQUEST or TAU REQUEST message and a T3324' value that repeats the T3324 / T3324' value contained in the ATTACH REQUEST or TAU REQUEST message. In other words, the MME 114 accepts the recommendation of the UE 102. The UE 102 then enters PSM upon expiration of T3324', which starts immediately when the UE 102 receives the PSM configuration from the network.

[0083] In some implementations, the MME 114 may include the original T3324 Value IE in the PSM configuration instead of the T3324' Value IE. In one implementation, in addition to the PSM configuration, the MME 114 also provides a distance threshold in the ATTACH ACCEPT or TAUACCEPT message, which the UE 102 uses to check whether it needs to perform a TAU based on the distance it has traveled. As an alternative to the above implementation, the eNB 104 broadcasts the above-mentioned distance threshold in the system information block.

[0084] After receiving the ATTACH ACCEPT or TAU ACCEPT message, the UE 102 starts 1009 a T3324' timer. When the T3324' timer expires, the UE 102 transitions 1010 to PSM and starts T3412. In some implementations, the UE 102 also starts an inactivity timer after receiving the ATTACH ACCEPT or TAU ACCEPT message, and when the inactivity timer expires, the UE 102 then transitions to the RRC_IDLE state before transitioning to PSM. In other implementations, after receiving the ATTACH ACCEPT or TAU ACCEPT message, the UE also receives an RRC connection release message from the eNB 104 via the satellite 304, and transitions to the RRC_IDLE state before transitioning to PSM in response to the RRC connection release message. If the UE 102 transitions to the RRC_IDLE state before transitioning to PSM, the UE 102 starts T3412 when transitioning to the RRC_IDLE state instead of when transitioning in PSM.

[0085] At a later time, the UE 102 in PSM is no longer within the service area of ​​the satellite 304 because the satellite 304 has moved 1012 to a new location such that the satellite 304 cannot cover the UE 102. Thereafter, the UE 102 detects 1014 that it has traveled a distance greater than a distance threshold provided by the MME 114 or by the eNB 104. When the UE 102 detects that the satellite 306 has begun 1016 serving the area (i.e., has begun covering the UE 102), the UE 102 performs an RRC connection establishment procedure with the eNB 106 and transmits 1018 a TAU REQUEST message to the eNB 106 to inform the MME 114 of the updated UE location. The UE 102 may include updated T3324 / T3324' values ​​and updated T3412 / T3412' extension values ​​in the TAU REQUEST message, wherein the updated T3324 / T3324' values ​​and the updated T3412 / T3412' extension values ​​are determined by the UE 102 based on the new UE location information and the satellite ephemeris information. In one implementation, the UE 102 also includes an additional flag IE or other indicator in the TAU REQUEST message to indicate whether the UE estimates the period of satellite coverage to generate the T3324 and T3412 values.

[0086] The eNB 106 forwards 1020 the TAU REQUEST message from the UE 102 to the MME 114, and then receives 1022 a TAU ACCEPT message from the MME 114 in response to the TAU REQUEST message. The TAU ACCEPT message may include a T3412 extension value that repeats the T3412 / T3412' extension value transmitted in the TAU REQUEST message, a T3324' value that repeats the T3324 / T3324' value transmitted in the TAU REQUEST message, and an updated distance threshold. The UE 102, upon receiving 1024 the TAU ACCEPT message, replaces the stored T3324' value and the T3412 extension value with the new value contained in the TAU ACCEPT message, and then starts 1025 the timer T3324'. At the expiration of T3324', the UE 102 enters 1026 PSM and starts T3412. In some cases, the UE 102 may transition to the RRC_IDLE state before entering PSM. In these cases, the UE 102 starts the T3412 timer earlier when the UE 102 transitions to the RRC_IDLE state. Shortly after the UE 102 transitions to PSM, the satellite 306 moves 1028 to a new location such that the satellite 306 cannot cover the UE 102.

[0087] After the timer T3412 expires 1030, the UE 102 needs to perform a periodic TAU with the MME 114. The UE 102 waits until an upcoming satellite (e.g., the satellite 304 connected to the eNB 104) starts 1032 serving the area where the UE 102 is located, and then the UE 102 transmits 1034 a TAU REQUEST to the MME 114 via the eNB 104. When sending the TAU REQUEST message, the UE 102 may indicate that it supports extended periodic timer values ​​(e.g., via the MS Network Feature Support IE), and includes a T3324 / T3324' value and a T3412 / T3412' extension value, wherein the T3324 / T3324' value and the T3412 / T3412' extension value are determined by the UE 102 based on the UE location information and the satellite ephemeris information. UE 102 may also include an additional indication in the TAU REQUEST message to indicate whether the included T3324 and T3412 values ​​are based on a period of estimated or predicted satellite coverage by the UE. eNB 104 then forwards 1036 the TAU REQUEST message to MME 114. In response to the TAU REQUEST message, MME 114 transmits 1038 a TAU ACCEPT message to UE 102 via eNB 104. The message may include a T3412 extension value that repeats the T3412 / T3412' extension value included in the TAU REQUEST message, a T3324' value that repeats the T3324 / T3324' value included in the TAU REQUEST message, and an updated distance threshold. The UE 102, upon receiving 1040 the TAU ACCEPT message, replaces the stored T3324' value and the T3412 extension value with the new values ​​contained in the TAU ACCEPT message, and then starts 1041 T3324'.

[0088] In one implementation, the MME 114 may transmit another instance of T3412 in the ATTACH ACCEPT or TAU ACCEPT message instead of the T3412 Extension Value IE. Upon receiving the ATTACH ACCEPT or TAU ACCEPT message containing this T3412 instance, the UE 102 starts T3412 immediately instead of when the UE transitions to the RRC_IDLE state or enters PSM. In one implementation, this T3412 instance has the same value or the same value range as the T3412 Extension Value IE.

[0089] Fig.11is a flow chart of an example method 1100 that can be implemented in a UE (eg, UE 102 in the present disclosure) that is capable of obtaining its location information (eg, GNSS coordinates). The method 1100 is for determining how to apply a PSM configuration and when to perform a TAU under PSM.

[0090] Initially, at block 1102, the UE has established an RRC connection with an eNB operating in the NTN, and sends an ATTACH REQUEST or TAU REQUEST message containing the UE's location information to the network (i.e., MME). The UE may also include a T3412 extension value and a T3324 value in the ATTACH REQUEST or TAU REQUEST message. At block 1104, the RRC_CONNECTED UE receives an ATTACH ACCEPT or TAU ACCEPT message containing the T3412 extension value and the distance threshold. The ATTACH ACCEPT or TAU ACCEPT message may also contain a T3324 value or a T3324' value. If, at block 1106, the UE determines that the ATTACH ACCEPT or TAU ACCEPT message contains a (legacy) T3324 value, the process proceeds to block 1116, where the UE waits until it receives an RRC connection release message from the network, or until its inactivity timer expires. Then at block 1118, the UE transitions to the RRC_IDLE state and monitors paging according to its DRX or eDRX configuration. At block 1118, upon transitioning to the RRC_IDLE state, the UE also starts timers T3324 and T3412. Upon expiration of T3324, at block 1120, the UE transitions to PSM, and the flow proceeds to block 1122.

[0091] On the other hand, if the UE determines at block 1106 that the ATTACH ACCEPT or TAU ACCEPT message contains a T3324' value, the flow proceeds to block 1108, where the UE immediately starts timer T3324' upon receiving the ATTACH ACCEPT or TAU ACCEPT message. The flow then proceeds to block 1210, and the UE checks which of the following events occurs earlier: a) the UE receives an RRC connection release message from the network, b) the inactivity timer expires, or c) the timer T3324' expires. If the UE receives an RRC connection release message or the inactivity timer expires before the timer T3324' expires, the flow proceeds to block 1112, where the UE starts timer T3412, transitions to RRC_IDLE state, and monitors paging according to its DRX or eDRX configuration. When T3324' expires, at block 1114, the UE transitions to PSM. If at block 1110, the UE determines that timer T3324' expires before the UE receives the RRC connection release message and before the inactivity timer expires, the flow proceeds to block 1114, where the UE directly transitions past the RRC_IDLE state, directly enters the PSM, and starts timer T3412. Depending on the implementation, the UE may transition from RRC_CONNECTED to the RRC_IDLE state and to the PSM, or directly from RRC_CONNECTED to the PSM.

[0092] After entering PSM, at blocks 1122 and 1126, the UE continuously or periodically checks whether it has traveled a distance greater than a distance threshold and also checks whether T3412 has expired. If either of the above is true, the flow proceeds to block 1124 where the UE waits until it is covered by the upcoming / next satellite and then establishes an RRC active connection with the satellite's eNB (transitions to RRC_CONNECTED mode) in order to perform periodic TAUs or update the network with the latest UE location information, i.e., such that the transmission of the TAU request is delayed until the UE has entered the coverage area of ​​the Radio Access Network (RAN) connected to the core network.

[0093] Fig.1212 is a flow chart of an example method 1250 that can be implemented by a UE (e.g., UE 102 in the present disclosure) that is capable of obtaining its location information (e.g., GNSS coordinates), the example method being used to determine how to apply a PSM configuration and when to perform a TAU under PSM. Initially, at block 1252, the UE has established an RRC connection with an eNB operating in an NTN, and sends an ATTACH REQUEST or TAU REQUEST message containing the UE's location information to the network (i.e., MME). Thereafter, at block 1254, the RRC_CONNECTED UE receives an ATTACH ACCEPT or TAU ACCEPT message containing a PSM configuration (e.g., a T3412 value and a T3324 value) and a distance threshold. The process proceeds to block 1260, and the UE checks whether the UE receives an RRC connection release message from the network. If the UE receives an RRC connection release message, the process proceeds to block 1262, at which the UE transitions to an RRC_IDLE state and monitors paging according to its DRX or eDRX configuration. At block 1264, the UE transitions to PSM.

[0094] After entering PSM, at block 1272, the UE continuously or periodically checks whether it has traveled a distance greater than a distance threshold. If at block 1272, the UE determines that it has exceeded the distance threshold, the flow proceeds to block 1274, where the UE waits until it is covered by the upcoming / next satellite and then establishes an RRC connection with the satellite's eNB in ​​order to perform a periodic TAU or update the network with the latest UE location information, i.e., such that the transmission of the TAU request is delayed until the UE has entered the coverage area of ​​the Radio Access Network (RAN) connected to the core network. If the UE has not traveled a distance greater than the distance threshold, then at block 1272, the UE continues to check whether it has traveled a distance greater than the distance threshold.

[0095] Fig.13A13 is a flow chart of an example method 1300 that can be implemented by a UE capable of estimating / predicting satellite coverage (e.g., UE 102 in the present disclosure) for determining how to apply a PSM configuration and when to perform a TAU under PSM. Initially, at box 1302, the UE has established an RRC connection with an eNB operating in an NTN and sends an ATTACH REQUEST or TAUREQUEST message to the network (i.e., MME) containing information that implies or indicates whether the UE is able to estimate / predict the period of satellite coverage. In one implementation, the UE includes an explicit indication in the ATTACH REQUEST or TAU REQUEST message to indicate whether the UE is able to estimate / predict the period of satellite coverage. In another implementation, the UE includes T3324' and / or T3412' instead of T3324 and / or T3412 in the ATTACH REQUEST or TAU REQUEST message to indicate the period of satellite coverage that the UE is able to estimate / predict. Thereafter, at box 1304, the RRC_CONNECTED UE receives an ATTACH ACCEPT or TAU ACCEPT message containing the T3412 extension value and the distance threshold. The ATTACH ACCEPT or TAU ACCEPT message may also contain a T3324 value or a T3324' value. If the UE determines at box 1306 that the ATTACH ACCEPT or TAU ACCEPT message contains the old T3324 value, the process proceeds to box 1316, where the UE waits until it receives an RRC connection release message from the network, or until its inactivity timer expires. Then, at box 1318, the UE transitions to the RRC_IDLE state and monitors paging according to its DRX or eDRX configuration. At box 1318, upon transitioning to the RRC_IDLE state, the UE also starts timers T3324 and T3412. When T3324 expires, at block 1320 , the UE transitions to PSM and the flow proceeds to block 1322 .

[0096] On the other hand, if the UE determines at block 1306 that the ATTACH ACCEPT or TAU ACCEPT message contains a T3324' value, the flow proceeds to block 1308, where the UE immediately starts timer T3324' upon receiving the ATTACH ACCEPT or TAU ACCEPT message. The flow then proceeds to block 1310, and the UE checks which of the following events occurs earlier: a) the UE receives an RRC connection release message from the network, b) the inactivity timer expires, and c) the timer T3324' expires. If the UE receives an RRC connection release message or the inactivity timer expires before the timer T3324' expires, the flow proceeds to block 1312, where the UE starts timer T3412, transitions to RRC_IDLE state, and monitors paging according to its DRX or eDRX configuration. When T3324' expires, at block 1314, the UE transitions to PSM. If at block 1310, timer T3324' expires before the UE receives the RRC connection release message and before the inactivity timer expires, flow proceeds to block 1314 where the UE skips the RRC_IDLE state, transitions directly to PSM, and starts timer T3412.

[0097] After entering PSM, the UE continuously or periodically checks whether it has traveled a distance greater than a distance threshold and also checks whether T3412 has expired at blocks 1322 and 1326. If either of the above is true, the flow proceeds to block 1324 where the UE waits until it is covered by the upcoming / next satellite and then establishes an RRC connection with the satellite's eNB in ​​order to perform periodic TAUs or update the network with the UE's latest location information.

[0098] Fig. 13B13 is a flow chart of an example method 1350 that can be implemented by a UE capable of estimating / predicting satellite coverage (e.g., UE 102 in the present disclosure) for determining how to apply a PSM configuration and when to perform a TAU under PSM. Initially, at box 1352, the UE has established an RRC connection with an eNB operating in an NTN and sends an ATTACH REQUEST or TAUREQUEST message to the network (i.e., MME) containing information that implies or indicates whether the UE is able to estimate / predict the period of satellite coverage. In one implementation, the UE includes an explicit indication in the ATTACH REQUEST or TAU REQUEST message to indicate whether the UE is able to estimate / predict the period of satellite coverage. Thereafter, at box 1354, the RRC_CONNECTED UE receives an ATTACH ACCEPT or TAU ACCEPT message containing a distance threshold. The process proceeds to box 1360, and the UE checks whether the UE receives an RRC connection release message from the network. If the UE receives an RRC connection release message, the flow proceeds to block 1362 where the UE transitions to the RRC_IDLE state and monitors paging according to its DRX or eDRX configuration. Then, at block 1364, the UE transitions to PSM. If, at block 1360, the UE does not receive an RRC connection release message, the UE skips the RRC_IDLE state and directly transitions 1364 to PSM.

[0099] After transitioning 1364 to PSM, at block 1372, the UE continuously checks whether it has traveled a distance greater than the distance threshold. If the UE has traveled a distance greater than the distance threshold, flow proceeds to block 1374 where the UE waits until it is covered by the upcoming / next satellite and then establishes an RRC connection with the satellite's eNB in ​​order to perform periodic TAUs or update the network with the UE's latest location information. If the UE has not traveled a distance greater than the distance threshold, at block 1372, the UE continues to check whether it has traveled a distance greater than the distance threshold.

[0100] According to any one of methods 1100, 1250, 1300, and 1350, before the UE determines that the UE is within the coverage of the upcoming / next satellite, the UE may turn off its radio frequency (RF) receiver or put the RF receiver into low power mode. After the UE determines that the UE is within the coverage of the upcoming / next satellite, the UE may turn on the RF receiver or transition the RF receiver to normal mode. When the RF receiver is turned on or the RF receiver is in normal mode, the UE receives and synchronizes the DL signal from the upcoming / next satellite and receives system information from the upcoming / next satellite using the RF receiver. After receiving the system information, the UE performs a random access procedure with the upcoming / next satellite to establish an RRC connection. In other implementations, before the UE determines that the UE is within the coverage of the upcoming / next satellite, the UE may put its NTN modem (i.e., RF receiver and baseband) into low power mode. After the UE determines that the UE is within the coverage of the upcoming / next satellite, the UE may transition the NTN modem to normal mode. When the NTN modem is entered into normal mode, the UE receives and synchronizes the DL signal from the upcoming / next satellite and receives system information from the upcoming / next satellite using the NTN modem. After receiving the system information, the UE performs a random access procedure with the upcoming / next satellite to establish an RRC connection.

[0101] Although the above examples mainly involve eNBs connected to satellites 304, 306, etc., these techniques can also be applied to other types of base stations, such as gNBs. Similarly, although the above examples mainly involve MMEs, these techniques can also be applied to other types of core network nodes, such as AMFs.

[0102] For further clarity, Fig.14 A flow chart of an example method 1400 that may be implemented in a UE of the present disclosure is depicted. At block 1402, the UE receives a distance threshold from a base station connected to a core network while in a first location (events 908, 907, and 1008; blocks 1104, 1254, 1304, 1354). At block 1404, the UE determines that the current UE location has exceeded the distance threshold relative to the first location (events 914 and 1014; blocks 1122, 1272, 1322, 1372). At block 1406, the UE initiates a process for reporting current UE location information to a core network, such as an MME (events 918, 917, and 1018; blocks 1124 / 1102, 1274 / 1252, 1324 / 1302, 1374 / 1352).

[0103] at last, Fig.15A flow chart of an example method 1500 that may be implemented in a network device such as a base station or MME of the present disclosure is depicted. At block 1502, the network device determines a distance threshold within which the UE may avoid reporting location information when operating under PSM. At block 1504, the network device transmits the distance threshold to the UE (events 908, 907, and 1008; blocks 1104, 1254, 1304, 1354). At block 1506, when the UE has exceeded the distance threshold (events 918, 917, and 1018), the network device receives location information from the UE.

[0104] The following description can be applied to the above description.

[0105] In general, the description of one of the above figures may apply to another of the above figures. Any of the above events or boxes may be optional. For example, an event or box with a dashed line may be optional. In some implementations, "message" is used, and "message" may be replaced with "information element (IE)", and vice versa. In some implementations, "IE" is used and "IE" may be replaced with "field", and vice versa. In some implementations, "configuration" or "configuration parameter" may be replaced with "configuration", and vice versa. "eNB" may be replaced with "base station", "gNB", "6G base station", "evolved gNB" or 6G gNB. "ATTACH REQUEST" message and "ATTACHACCEPT" message may be replaced with "REGISTRATION REQUEST" message and "REGISTRATION ACCEPT" message, respectively. "MME" may be replaced with AMF or evolved AMF or 6G AMF. "RRC connection release message" may be replaced with "RRC release message".

[0106] The user device (e.g., UE 102) in which the technology of the present disclosure can be implemented can be any suitable device capable of wireless communication, such as a smart phone, a tablet computer, a laptop computer, a mobile game console, a point of sale (POS) terminal, a health monitoring device, a drone, a camera, a media streaming dongle or another personal media device, a wearable device such as a smart watch, a wireless hotspot, a femtocell or a broadband router. Further, in some cases, the user device can be embedded in an electronic system, such as a head unit or an advanced driver assistance system (ADAS) of a vehicle. Still further, the user device can be operated as an Internet of Things (IoT) device or a mobile Internet device (MID). Depending on the type, the user device may include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

[0107] Certain embodiments are described in the present disclosure as including logic or multiple components or modules. A module may be a software module (e.g., a code or machine-readable instruction stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit that is capable of performing certain operations and may be configured or arranged in a particular manner. A hardware module may include dedicated circuitry or logic that is permanently configured to perform certain operations (e.g., as a dedicated processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.). A hardware module may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations (e.g., as contained in a general-purpose processor or other programmable processor). The decision to implement a hardware module with a dedicated and permanently configured circuit or with a temporarily configured circuit (e.g., configured by software) may be driven by cost and time considerations.

[0108] When implemented in software, the techniques may be provided as part of an operating system, a library used by multiple applications, a specific software application, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors.

[0109] According to a first example, a method for initiating a process for reporting location information is implemented in a UE. The method includes: (1) receiving a distance threshold from a base station connected to a core network when in a first location; and (2) in response to determining that the current UE location has exceeded the distance threshold relative to the first location, initiating a process for reporting the current UE location information to the core network.

[0110] A second example is a method according to the first example, wherein determining that the UE has exceeded a distance threshold comprises determining that the UE has travelled at least the distance threshold from a first location within a cell of the base station.

[0111] A third example is a method according to the second example, further comprising transmitting an indication of an initial location of the UE to the base station before receiving the distance threshold.

[0112] A fourth example is a method according to any one of the first to third examples, wherein initiating a process for reporting current UE location information includes transmitting a TAU request message to a core network.

[0113] The fifth example is a method according to the fourth example, further comprising receiving a TAU accept message including a new distance threshold in response to the TAU request message.

[0114] A sixth example is a method according to the fourth or fifth example, wherein the initiating procedure includes delaying transmission of the TAU request until the UE has entered a coverage area of ​​a radio access network (RAN) connected to the core network.

[0115] A seventh example is a method according to any one of the first to sixth examples, wherein receiving the distance threshold comprises receiving a system information block (SIB) broadcast in a cell, the SIB comprising the distance threshold.

[0116] An eighth example is a method according to any one of the first to sixth examples, wherein receiving the distance threshold comprises receiving a message addressed solely to the UE from the base station, the message comprising the distance threshold.

[0117] A ninth example is the method according to the eighth example, wherein the message is an ATTACH ACCEPT message.

[0118] The tenth example is the method according to the eighth example, wherein the message is a TAU ACCEPT message.

[0119] An eleventh example is a method according to any one of the first to tenth examples, wherein determining that a current UE position has exceeded a distance threshold relative to a first position occurs when the UE is operating in a power saving mode (PSM).

[0120] The twelfth example is a method according to the eleventh example, further comprising: (1) before entering PSM, transmitting a first value of a timer to a base station, which defines a time period during which the UE remains in an idle mode of a protocol for controlling radio resources; (2) receiving a second value different from the first value from the base station by one or more processors; and (3) entering PSM when the timer corresponding to the second value expires.

[0121] A thirteenth example is the method according to the twelfth example, wherein the timer is a T3324 timer.

[0122] A fourteenth example is a method according to any one of the first to thirteenth examples, wherein the base station is associated with a non-terrestrial network (NTN).

[0123] The fifteenth example is a UE comprising one or more processors and configured to implement a method as described in any one of the first to fourteenth examples.

[0124] The sixteenth example is a method for configuring a user equipment (UE) to report location information via a non-terrestrial network (NTN), the method being implemented in a network device. The method includes: (1) determining, by one or more processors, a distance threshold within which the UE can avoid reporting location information when operating in a power saving mode (PSM); (2) transmitting, by one or more processors, the distance threshold to the UE via a base station operating in the NTN; and (3) receiving, by one or more processors, location information from the UE when the UE has exceeded the distance threshold.

[0125] A seventeenth example is a method according to the sixteenth example, wherein receiving the location information is in response to the UE determining that the UE has traveled at least a distance threshold from the first location.

[0126] An eighteenth example is a method according to the sixteenth or seventeenth example, wherein determining the distance threshold is based on a current location of the UE, the current location corresponding to a set of geographic coordinates.

[0127] A nineteenth example is a method according to the sixteenth or seventeenth example, wherein determining the distance threshold is based on a current location of the UE, the current location corresponding to a geographical area in which the UE is currently operating.

[0128] The twentieth example is a method according to the sixteenth or seventeenth example, wherein determining the distance threshold is based on the current location of the UE, and the current location corresponds to a geographical area currently covered by one or more cells and in which the UE is currently operating.

[0129] The twenty-first example is a method according to any one of the eighteenth to twentieth examples, wherein determining the distance threshold is also based on a satellite constellation available to the UE at a current location and a current time.

[0130] The twenty-second example is a method according to any one of the eighteenth to twenty-first examples, further comprising, before the transmission distance threshold, receiving an indication of an initial position of the UE from the UE.

[0131] The twenty-third example is a method according to any one of the sixteenth to twenty-second examples, wherein receiving the location information includes receiving a TAU request message or an attach request message from the UE.

[0132] The twenty-fourth example is a method according to the twenty-third example, further comprising: (1) determining a new distance threshold in response to the TAU request message; and (2) transmitting a TAU accept message including the new distance threshold to the UE.

[0133] The twenty-fifth example is a method according to the sixteenth example, wherein transmitting the distance threshold to the UE includes broadcasting a system information block (SIB) including the distance threshold in a cell.

[0134] The twenty-sixth example is a method according to the sixteenth example, wherein transmitting the distance threshold to the UE includes transmitting a message individually addressed to the UE, the message including the distance threshold.

[0135] The twenty-seventh example is the method according to the twenty-sixth example, wherein the message is an ATTACH ACCEPT message.

[0136] The twenty-eighth example is the method according to the twenty-sixth example, wherein the message is a TAU ACCEPT message.

[0137] The twenty-ninth example is a method according to the sixteenth example, further including: (1) before entering PSM, receiving a first value of a timer from the UE, which defines a time period during which the UE remains in an idle mode of a protocol for controlling radio resources; (2) determining a second value of the timer; and (3) transmitting the second value of the timer to the UE, which second value is different from the first value.

[0138] The thirtieth example is a method according to any one of the first to twenty-ninth examples, which is implemented in a base station and also includes transmitting location information to a core network.

[0139] The thirty-first example is a network device operating in a non-terrestrial network (NTN) or a core network (CN), the network device comprising one or more processors and configured to implement a method as described in any one of the sixteenth to thirtieth examples.

Claims

1. A method (1400) for initiating a process for reporting UE location information, performed by a user equipment (102) UE connected to a core network (110) via a non-terrestrial network (105) NTN, the method comprising: When in the first position, before the UE enters (910) a power saving mode PSM, receiving (1402, 908) a distance threshold from the core network via the NTN; as well as While in the PSM, when the current UE location has exceeded the distance threshold relative to the first location, the process for reporting (918) the current UE location information is initiated (1406, 914).

2. The method of claim 1 , wherein receiving the distance threshold comprises: A timer value for determining a period during which the UE operates under the PSM is obtained, the period being related to NTN coverage for the UE.

3. The method according to any one of claims 1 or 2, further comprising: Before receiving the distance threshold, UE location information is transmitted to the core network via the NTN.

4. The method according to claims 1 to 3, wherein the initiating comprises: A tracking area update TAU request message or an attach request message including the current UE location information is transmitted to the core network via the NTN.

5. The method according to claim 4, further comprising: In response to the TAU request message or in response to the attach request message, a corresponding TAU accept or attach accept message is received, and the TAU accept or attach accept message updates the distance threshold.

6. The method according to claim 4 or 5, further comprising: The transmission of the TAU request or the attach request message is delayed until the UE has entered the coverage area of ​​the NTN.

7. The method according to any one of claims 1 to 6, wherein receiving the distance threshold comprises: A broadcasted system information block (SIB) including the distance threshold is received.

8. The method according to any one of claims 1 to 6, wherein the receiving the distance threshold comprises: A message addressed to the UE is received, the message including the distance threshold.

9. A user equipment UE (102), comprising: A transceiver (154, 156), a processor (152), and a computer-readable storage medium storing executable instructions for the processor to use the transceiver to perform any of the methods according to claims 1 to 9.

10. A method (1500) performed by a network device (110, 114, 164) for configuring a user equipment (102) UE to report current UE location information via a non-terrestrial network (NTN) (105), the method comprising: transmitting (1504) a distance threshold to the UE via the NTN, within which the UE avoids reporting the current UE location information when operating in a power saving mode (PSM); as well as The current UE location information indicating that the UE has exceeded the distance threshold is received (1506) from the UE via the NTN.

11. The method according to claim 10, further comprising: UE location information is received prior to the transmitting.

12. The method according to claim 11, further comprising: The distance threshold is determined using the UE location information and / or NTN coverage.

13. The method according to any one of claims 10 to 12, wherein the receiving the current UE location information comprises: receiving a tracking area update TAU request message or an attach request message from the UE, wherein the TAU request or the attach request message includes the current UE location information; Updating the distance threshold based on the current UE location information; as well as A TAU accept message including the updated distance threshold is transmitted.

14. The method according to any one of claims 10 to 13, wherein transmitting the distance threshold to the UE comprises: A system information block SIB including the distance threshold is broadcasted.

15. The method according to any one of claims 10 to 13, wherein transmitting the distance threshold to the UE comprises: A message addressed individually to the UE is transmitted, the message including the distance threshold.

16. The method according to any one of claims 10 to 15, further comprising: A timer value associated with a time period during which the UE operates under the PSM is transmitted to the UE.

17. The method according to any one of claims 10 to 16, wherein the transmitting the distance threshold adopts a first base station of the NTN, and the receiving the current UE location information adopts a second base station of the NTN.

18. A network device (110, 114, 116) connected to a user equipment (102) UE via a non-terrestrial network (105) NTN, the network device comprising a transceiver (144, 146), a processor (142) and a computer-readable storage medium storing executable instructions for the processor to use the transceiver to perform any of the methods according to claims 10 to 17.

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