Method, apparatus and system for non-terrestrial networks

Abstract

Described herein is a user equipment (UE) served by a serving cell of a network node and configured for supporting communications over a non-terrestrial network (NTN), the UE comprising: at least one processor; and at least one memory storing instructions that cause, when executed by the at least one processor, the UE to perform at least the following: receive, from a network node, information indicative of availability of a target cell related to a timing at which a serving cell will stop serving an area whose current service is; determining, based on the received information, an availability of the target cell related to a timing at which the serving cell stops serving the area at which it currently serves; determining a measurement-related behavior of the UE corresponding to the target cell based on the determined availability of the target cell; and performing measurement on the target cell according to the determined measurement-related behavior.

Description

Technical Field

[0001] The present disclosure relates to non-terrestrial networks (NTNs), and more particularly to methods, devices, and systems for supporting communications over NTNs. Background Art

[0002] Throughout the specification, any discussion of the background art should not be considered as an admission that this art is widely known or forms part of the common general knowledge in the field.

[0003] Recently, for example, the 3rd Generation Partnership Project (3GPP) has discussed supporting New Radio (NR) and the Internet of Things (IoT) over non-terrestrial networks (NTN). Broadly speaking, three types of service links have been defined that need to be supported, namely: • Geofixed: provided by beams that continuously cover the same geographical area (e.g., the case of geosynchronous orbit (GSO) satellites); • Quasi-Geo-fixed: provided by a beam covering one geographical area during a limited period of time and a different geographical area during another period of time (e.g. the case of non-GSO / NGSO satellites generating steerable beams); and • Geomobile: provided by beams whose coverage area slides over the Earth's surface (e.g., the case of NGSO satellites generating fixed or non-steerable beams).

[0004] In general, recent discussions seem to be focused on the use of (quasi-)geo-fixed or geo-mobile cells for targeted transparent payloads (typically referring to scenarios where Earth-based gNBs / eNBs relay to NTN-enabled UEs via satellite). Specifically, 3GPP Release 17 specifies that quasi-geo-fixed cells will broadcast the parameter t-service (e.g., in SIB19 for NR and SIB3 for IoT), which generally defines when the cell will stop serving the area it is currently serving. The t-service parameter is defined using TimeOffsetUTC, which is the time offset (in seconds) from Monday 00:00:00 UTC. Similarly, for IoT NTN, SIB32 specifies the related parameter t-serviceStart, which generally defines when the next cell will start serving the same area. It is important to note that this SIB32 applies only to discontinuous coverage scenarios, i.e., deployments where the number of satellites is insufficient to provide continuous coverage.

[0005] In recent meetings, the following potential issues have been identified and discussed: • If the UE is configured with "t-service-r17" and eDRX_cycle in the serving cell, the UE shall meet the requirements defined for a DRX cycle length of [2.56] seconds starting at least [K] seconds before "t-service-r17".

[0006] This is typically defined as follows: in order to be able to detect a new target cell serving the area of ​​the current serving cell (e.g., geofixed cell / EFC), a UE configured with an (extended) discontinuous reception (eDRX) cycle should comply with the 2.56-second DRX cycle requirement for at least K seconds (to be specified or determined) before tServiceStart. On the other hand, current specifications / standards of 2.56 seconds (DRX cycle) typically indicate that the UE should be able to detect a new cell (e.g., a cell from an incoming satellite) within time T = 58.88 seconds (or in other words, within 23 DRX cycles). In practice, this can result in a value for "K" being defined such that the UE is incentivized to wake up 58.88 seconds before tServiceStart, or even longer for enhanced coverage scenarios. It is worth noting that the above requirement / protocol (of K) seems to assume that the target cell will overlap with the current serving cell (in terms of radio coverage) for at least K seconds (i.e. close to 1 minute in some use cases), which is considered a significant limitation as the current specification does not even define that the target cell must be available before the serving cell disappears, i.e. the target cell may not even appear before t serving . Therefore, if the UE attempts to measure the target cell before t serving (i.e. before the target cell is available), the UE will most likely fail to detect the target cell and waste energy.

[0007] Therefore, in view of at least some or all of the above issues, it seems necessary to propose new mechanisms / techniques for supporting communications (e.g., NR and / or IoT communications) over NTNs, especially in an efficient, flexible and reliable manner. Summary of the Invention

[0008] According to one aspect of the present disclosure, there is provided a user equipment (UE) served by a serving cell of a network node and configured to support communications on a non-terrestrial network (NTN), the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least perform the following operations: receiving, from the network node, information indicating availability of a target cell related to a timing at which the serving cell will stop serving an area that it is currently serving; determining, based on the received information, availability of the target cell in relation to the timing at which the serving cell stops serving the area currently served by the serving cell; determining, based on the determined availability of the target cell, a measurement-related behavior of the UE corresponding to the target cell; and Perform measurement on the target cell according to the determined measurement-related behavior.

[0009] In some examples, based on determining that the target cell will be unavailable before the timing at which the serving cell will stop serving the area it is currently serving, determining the measurement-related behavior of the UE corresponding to the target cell involves at least one of the following: deferring the execution of the measurement on the target cell until the timing at which the serving cell will stop serving the area currently served by the serving cell; or A discontinuous reception (DRX) related configuration is applied, wherein the DRX cycle is shorter than the cycle currently configured on the UE.

[0010] In some examples, the information indicating the availability of the target cell includes flag information, where the flag information indicates at least one of the following: whether the target cell will be available before the serving cell stops serving the area it currently serves; whether the target cell will be available at least K seconds before the serving cell stops serving the area it is currently serving, where K is a preconfigured value greater than 0; whether to apply a DRX-related configuration that meets the predefined measurement requirements of the UE; whether to apply the low power consumption mode configuration of the UE; or Whether to apply the relaxed measurement configuration of the UE.

[0011] In some examples, the information indicating the availability of the target cell includes time information indicating when the target cell will be available.

[0012] In some examples, based on a determination that the target cell will be available before the serving cell stops serving the area it currently serves, determining the measurement-related behavior of the UE corresponding to the target cell involves: The execution of the measurement on the target cell is postponed until a timing when the target cell will be available.

[0013] In some examples, determining the availability of the target cell in relation to the timing at which the serving cell stops serving the area that it currently serves includes: determining, based on the received time information, whether the target cell will be available at least K seconds before the serving cell stops serving the area currently served, where K is a preconfigured value greater than or equal to 0; Wherein, based on a determination that the target cell will be available at least K seconds before the serving cell stops serving the area currently served, determining the measurement-related behavior of the UE corresponding to the target cell involves: applying a DRX-related configuration that meets predefined measurement requirements of the UE; and Wherein, based on the determination that the target cell will be unavailable at least K seconds before the serving cell stops serving the area currently served, determining the measurement-related behavior of the UE corresponding to the target cell involves at least one of the following: maintaining the current measurement-related configuration of the UE, or The DRX-related configuration of the UE is adjusted during K seconds before the serving cell stops serving the area it currently serves to enable the UE to monitor at least a preconfigured amount of measurements from neighboring cells.

[0014] In some examples, the information indicating the availability of the target cell is received in at least one of: a broadcast message, a higher layer message, or information of an assisted DRX configuration configured for the UE.

[0015] In some examples, the timing at which the serving cell will stop serving the area it currently serves is determined based on pre-configured parameters received by the UE from the network node.

[0016] According to another aspect of the present disclosure, there is provided a network node configured to support communication with a user equipment (UE) served by a serving cell of the network node over a non-terrestrial network (NTN), the network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network node to at least: determining the availability of a target cell relative to a timing at which the serving cell will stop serving an area it currently serves; and Information indicating availability of the target cell is sent to the UE.

[0017] In some examples, the information indicating the availability of the target cell includes flag information, where the flag information indicates at least one of the following: Flag information indicating at least one of the following: whether the target cell will be available before the serving cell stops serving the area it currently serves; whether the target cell will be available at least K seconds before the serving cell stops serving the area it is currently serving, where K is a preconfigured value greater than 0; whether to apply a DRX-related configuration that meets the predefined measurement requirements of the UE; whether to apply the low power consumption mode configuration of the UE; or whether to apply the relaxed measurement configuration of the UE; and / or Time information indicating when the target cell will be available.

[0018] In some examples, the information indicating the availability of the target cell is sent to the UE via at least one of: a broadcast message, a higher layer message, or a secondary DRX configuration of the UE.

[0019] According to yet another aspect of the present disclosure, there is provided a method for a user equipment (UE) served by a serving cell of a network node and configured to support communication over a non-terrestrial network (NTN), the method comprising: receiving, from the network node, information indicating availability of a target cell related to a timing at which the serving cell will stop serving an area that it is currently serving; determining, based on the received information, availability of the target cell in relation to the timing at which the serving cell stops serving the area currently served by the serving cell; determining, based on the determined availability of the target cell, a measurement-related behavior of the UE corresponding to the target cell; and Perform measurement on the target cell according to the determined measurement-related behavior.

[0020] According to yet another aspect of the present disclosure, there is provided a method of a network node configured to support communication with a user equipment (UE) served by a serving cell of the network node over a non-terrestrial network (NTN), the method comprising: determining the availability of a target cell relative to a timing at which the serving cell will stop serving an area it currently serves; and Information indicating availability of the target cell is sent to the UE.

[0021] According to yet another aspect of the present disclosure, a computer program is provided, comprising instructions for causing a device to execute the method disclosed in the present disclosure.

[0022] According to yet another aspect of the present disclosure, a memory is provided, wherein the memory stores computer-readable instructions for causing a device to execute the method disclosed in the present disclosure.

[0023] Furthermore, according to some example embodiments, a user equipment (UE) served by a serving cell of a network node and configured to support communications over a non-terrestrial network (NTN) is provided, the UE comprising corresponding appropriate means configured to perform the corresponding steps disclosed in the present disclosure.

[0024] Similarly, according to some example embodiments, there is also provided a network node configured to support communication with a user equipment (UE) served by a serving cell of the network node over a non-terrestrial network (NTN), the network node comprising corresponding appropriate components configured to perform the corresponding steps disclosed in the present disclosure.

[0025] In addition, according to some other example embodiments, for example, a computer program product for a wireless communication device is provided, the wireless communication device including at least one processor, the processor including software code portions for executing the corresponding steps disclosed in the present disclosure when the product is executed on the device. The computer program product may include a computer-readable medium storing the software code portions. Furthermore, the computer program product may be directly loaded into the internal memory of the computer and / or transmitted via a network by at least one of uploading, downloading, and pushing a program.

[0026] Although some example embodiments will be described herein with particular reference to the aforementioned applications, it will be understood that the present disclosure is not limited to such fields of use and may be applied in a wider context.

[0027] It is worth noting that it should be understood that the methods according to the present disclosure relate to methods of operating the apparatus (or system) according to the above-described example embodiments and their variations, and that corresponding statements regarding the apparatus (or system) also apply to the corresponding methods, and vice versa. Therefore, similar descriptions may be omitted for the sake of brevity. In addition, even if not explicitly disclosed, the above-described aspects may be combined in various ways. Those skilled in the art will understand that combinations of these aspects and features / steps are possible unless expressly excluded contradictions arise.

[0028] Implementations of the disclosed apparatus may include the use of, but are not limited to, one or more processors, one or more application-specific integrated circuits (ASICs), and / or one or more field-programmable gate arrays (FPGAs). Implementations of the apparatus may also include the use of other conventional and / or custom hardware, such as software-programmable processors, such as graphics processing unit (GPU) processors.

[0029] Other and further example embodiments of the present disclosure will become apparent during the course of the following discussion and with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Example embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0031] Figure 1A and 1B Two possible example use cases are schematically illustrated, which respectively illustrate the temporal relationship between an old (serving) cell and a new (target) cell according to some example embodiments of the present disclosure;

[0032] Figure 2A and 2B Schematically illustrates some example embodiments of the present disclosure. Figure 1A and 1B Two example signaling / messaging flow diagrams for the use case of

[0033] Figure 3 An example flow chart schematically illustrating UE behavior according to some example embodiments of the present disclosure; and

[0034] Figure 4 Examples of implementation of apparatus according to some example embodiments of the present disclosure are schematically illustrated. DETAILED DESCRIPTION

[0035] It should be noted that, unless otherwise specified, the same or similar reference numerals used in the drawings of the present disclosure may denote the same or similar elements. Similarly, unless otherwise specified, the same or similar messages (and the contents included therein) used in the drawings of the present disclosure may denote the same or similar messages (and the contents thereof), so that their repeated description may be omitted for the sake of brevity.

[0036] Various exemplary embodiments will be described below using a communication network architecture based on 3GPP communication network standards (e.g., 5G / NR / IoT) as an example of a communication network to which the embodiments are applicable. However, the embodiments are not limited to such architectures. It will be apparent to those skilled in the art that these embodiments may also be applied to other types of communication networks, such as Wi-Fi, Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth®, Personal Communications Service (PCS), ZigBee®, Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, Mobile Ad Hoc Networks (MANETs), wired access, and the like, in which mobile communication principles are integrated with D2D (Device-to-Device) or V2X (Vehicle-to-Everything) configurations (e.g., SL (Sidelink)). Furthermore, without loss of generality, some examples of the embodiments are described with respect to mobile communication networks, but the principles of the present disclosure can be extended to and applied to any other type of communication network, such as wired communication networks.

[0037] The following examples and embodiments should be understood as illustrative examples only. Although this specification may refer to "one," "an," or "some" examples or embodiments in multiple places, this does not necessarily mean that each such reference relates to the same example or embodiment, nor does it mean that the feature applies only to a single example or embodiment. Individual features of different embodiments may also be combined to provide other embodiments. In addition, terms such as "including" and "comprising" should be understood as not limiting the embodiments to consisting only of the features mentioned; such examples and embodiments may also include features, structures, units, modules, etc. that are not specifically mentioned.

[0038] A basic system architecture of a (telecommunication) communication network, including a mobile communication system, in which certain example embodiments apply, may include an architecture of one or more communication networks, including one or more radio access network subsystems and a core network. Such an architecture may include one or more communication network control units or functions, access network units, radio access network units, access service network gateways, or base transceiver stations, such as base stations (BSs), access points (APs), NodeBs (NBs), eNBs or gNBs, distributed units (DUs), or central units (CUs), for controlling a corresponding coverage area or cell, and one or more communication stations (e.g., communication units or functions) capable of communicating via one or more communication beams via one or more channels for transmitting several types of data in multiple access domains, such as user equipment or terminal equipment (e.g., UEs) or another device with similar functionality (e.g., modem chipsets, chips, modules, etc.), which may also be part of a station, unit, function, or application capable of performing communication, such as a UE, a unit or function capable of machine-to-machine communication architecture, or as a separate unit attached to such a unit, function, or application capable of performing communication. In addition, core network elements or network functions may also be included, such as gateway network elements / functions, mobility management entities, mobile switching centers, servers, databases, etc.

[0039] The following description may provide further details of alternatives, modifications and variants: The gNB includes, for example, a node that provides NR user plane and control plane protocol terminations to the UE and is connected to the 5GC via an NG interface, for example in accordance with 3GPP TS 38.300 V16.6.0 (2021-06) section 3.2 (incorporated by reference).

[0040] The gNB Central Unit (gNB-CU) includes, for example, a logical node that hosts, for example, the RRC, SDAP, and PDCP protocols for the gNB or the RRC and PDCP protocols for the en-gNB, and controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface with the gNB-DU.

[0041] The gNB distributed unit (gNB-DU) includes, for example, a logical node that hosts the RLC, MAC, and PHY layers of a gNB or en-gNB, and whose operation is partially controlled by the gNB-CU. A gNB-DU supports one or more cells. A cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface with the gNB-CU.

[0042] The gNB-CU control plane (gNB-CU-CP) comprises, for example, a logical node that hosts the control plane portion of the PDCP protocol and RRC for an en-gNB or gNB-CU of a gNB. The gNB-CU-CP terminates the E1 interface with the gNB-CU-UP and the F1-C interface with the gNB-DU.

[0043] The gNB-CU user plane (gNB-CU-UP) includes, for example, a logical node that hosts the user plane portion of the PDCP protocol for the gNB-CU of the en-gNB, and the user plane portions of the SDAP protocol and the PDCP protocol for the gNB-CU of the gNB. The gNB-CU-UP terminates, for example, the E1 interface with the gNB-CU-CP and the F1-U interface with the gNB-DU in accordance with 3GPP TS 38.401 V16.6.0 (2021-07), section 3.1 (incorporated by reference).

[0044] Different divisions of functionality between central and distributed units are possible, for example, called options:

[0045] Option 1 (similar to 1A): oThe functional division in this option is similar to the 1A architecture in DC. RRC is located in the central unit. PDCP, RLC, MAC, physical layer, and RF are located in the distributed unit.

[0046] Option 2 (similar to the 3C division): oThe functional division in this option is similar to the 3C architecture in DC. RRC and PDCP are located in the central unit. RLC, MAC, physical layer, and RF are located in the distributed unit.

[0047] Option 3 (partitioning within RLC): o The lower RLC layer (part of the RLC functionality), MAC, physical layer, and RF are located in the distributed unit. PDCP and upper RLC layers (other parts of the RLC functionality) are located in the central unit.

[0048] Option 4 (RLC-MAC partition): The oMAC, physical layer, and RF are located in the distributed unit, while the PDCP and RLC are located in the central unit.

[0049] Or, for example, operate in accordance with 3GPP TR 38.801 V14.0.0 (2017-03) section 11 (incorporated by reference).

[0050] gNB supports different protocol layers, such as Layer 1 (L1) - the physical layer.

[0051] NR's Layer 2 (L2) is divided into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), among which, for example: oThe physical layer provides transport channels to the MAC sublayer; oMAC sublayer provides logical channels to RLC sublayer; oRLC sublayer provides RLC channels to PDCP sublayer; The oPDCP sublayer provides radio bearers to the SDAP sublayer; The oSDAP sublayer provides 5GC QoS flows; oComp. refers to header compression, Segm. refers to segmentation; oControl channels include (BCCH, PCCH).

[0052] Layer 3 (L3) includes, for example, Radio Resource Control (RRC), for example according to 3GPP TS 38.300 V16.6.0 (2021-06) Section 6 (incorporated by reference).

[0053] A RAN (Radio Access Network) node or network node, such as a gNB, base station, gNB CU or gNB DU or part thereof, may be implemented using, for example, a device having at least one processor and / or at least one memory with computer-readable instructions (computer program), the device being configured to support and / or provide and / or process CU and / or DU related functions and / or features, and / or at least one protocol (sub) layer of a RAN (Radio Access Network), such as Layer 2 and / or Layer 3.

[0054] The gNB CU and gNB DU components can be, for example, co-located or physically separated. The gNB DU can be further divided, for example, into two parts, one containing processing equipment and the other containing antennas. The central unit (CU) may also be referred to as the BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or a portion thereof. The distributed unit (DU) may also be referred to as the RRH / RRU / RE / RU, or a portion thereof. Hereinafter, in various exemplary embodiments of the present disclosure, the CU-CP (or more generally, the CU) may also be referred to as a (first) network node supporting at least one of the central unit control plane functions or the radio access network Layer 3 protocols; similarly, the DU may also be referred to as a (second) network node supporting at least one of the distributed unit functions or the radio access network Layer 2 protocols.

[0055] A gNB-DU supports one or more cells and can therefore serve as, for example, a serving cell for a user equipment (UE).

[0056] User equipment (UE) may include a wireless or mobile device, an apparatus having a radio interface for interacting with a RAN (Radio Access Network), a smartphone, an in-vehicle device, an IoT device, an M2M device, or other device. Such a UE or apparatus may include: at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to perform at least certain operations, such as establishing an RRC connection with the RAN. For example, the UE is configured to generate a message (e.g., including a cell ID) to be sent over the air to the RAN (e.g., to reach and communicate with a serving cell). The UE may generate, send, and receive RRC messages containing one or more RRC PDUs (Packet Data Units).

[0057] The UE may have different states (e.g., according to 3GPP TS 38.331 V16.5.0 (2021-06) sections 42.1 and 4.4 (incorporated by reference)).

[0058] For example, when an RRC connection is established, the UE is in an RRC_CONNECTED state or an RRC_INACTIVE state.

[0059] In the RRC_CONNECTED state, the UE can: oStore AS context; o Transmit unicast data to / from UE; o monitor a control channel associated with a shared data channel to determine whether data is scheduled for the data channel; oProvide channel quality and feedback information; oPerform neighbor cell measurements and measurement reporting.

[0060] The RRC protocol includes the following main functions: oRRC connection control; oMeasurement configuration and reporting; o Establishment / modification / release of measurement configurations (e.g., intra-frequency, inter-frequency, and inter-RAT measurements); oMeasurement of gap creation and release; oMeasurement report.

[0061] The general functionality and interconnection of the units and functions (which also depends on the actual network type) are known to those skilled in the art and are described in the corresponding specifications, so for the sake of brevity, their detailed description may be omitted herein. However, it should be noted that in addition to the units, functions or applications described in detail below, a number of additional network units and signaling links may be used to communicate with the units, functions or applications, such as communication endpoints, communication network control units (e.g., servers, gateways, radio network controllers), and other units of the same or other communication networks.

[0062] The communication network architecture considered in the examples of the embodiments can also communicate with other networks (e.g., the public switched telephone network or the internet). The communication network can also support the use of cloud services for virtualized network elements or their functions. It should be noted that the virtualized network portion of the telecommunications network can also be provided by non-cloud resources (e.g., an on-premises network). It should be understood that network elements and / or corresponding functions of access systems, core networks, etc. can be implemented using any node, host, server, access node, or entity suitable for such purpose. Generally, network functions can be implemented as network elements on dedicated hardware, as software instances running on dedicated hardware, or as virtualized functions instantiated on a suitable platform (e.g., a cloud infrastructure).

[0063] Furthermore, network units (e.g., communication units, such as UEs, terminal devices), control units or functions (e.g., access network units, such as base stations / BSs, gNBs, radio network controllers), core network control units or functions (e.g., gateway units), or other network units or functions (as described herein), as well as any other units, functions, or applications, may be implemented using software (e.g., a computer program product for a computer) and / or hardware. To perform their corresponding processing, the corresponding device, node, function, or network unit may include several components, modules, units, and components (not shown) required for control, processing, and / or communication / signaling functions. Such components, modules, units, and assemblies may include, for example, one or more processors or processor units, including one or more processing sections for executing instructions and / or programs and / or for processing data; storage units or memory units for storing instructions, programs, and / or data, serving as workspaces for the processors or processing sections, etc. (e.g., ROM, RAM, EEPROM, etc.); input or interface components for inputting data and instructions via software (e.g., floppy disks, CD-ROMs, EEPROM, etc.); user interfaces for providing monitoring and operational usability to a user (e.g., screens, keyboards, etc.); other interfaces or components for establishing links and / or connections under the control of the processor units or sections (e.g., wired and wireless interface components, radio interface components including, for example, antenna units, components for forming a radio communication section, etc.), etc., wherein the corresponding components forming the interfaces (e.g., the radio communication section) may also be located at a remote site (e.g., a radio head or radio station, etc.). It should be noted that, in this specification, a processing section should not be considered merely to represent a physical portion of one or more processors, but may also be considered to represent a logical division of processing tasks performed by one or more processors. It should be understood that, according to some examples, a so-called "fluid" or flexible network concept can be employed, wherein the operations and functional operations of a network element, network function, or another entity in the network can be flexibly performed in different entities or functions, such as nodes, hosts, or servers. In other words, the "division of labor" between the involved network elements, functions, or entities can vary depending on the situation.

[0064] Furthermore, broadly speaking, NTN can refer to user equipment (UE) or user nodes communicating with a network (and potentially the internet) via satellite or high-altitude platforms. In some possible implementations, the NTN can be considered to include one or more base stations, denoted as gNBs or similar. The gNBs can be installed on airborne vehicles, spaceborne vehicles, or similar. Spaceborne vehicles can include satellites in low Earth orbit (LEO), medium Earth orbit (MEO), geostationary orbit (GEO), or highly elliptical orbit (HEO). For example, a satellite containing a base station can also be referred to as a communication satellite. A communication satellite can be implemented as a regenerative payload (with gNBs performing onboard processing). The gNBs onboard a satellite can be configured to generate multiple beams within a given service area within its field of view. The beam footprint can refer to the land area over which the communication satellite's transponders provide cell coverage. Cell coverage can refer to the geographic area covered by the network. The satellite's field of view can be determined by the onboard antenna pattern and minimum elevation angle. The NTN can also include other base stations, such as one or more gNBs located at the ground level. In this context, the satellites can be understood as operating in some sort of amplify-and-forward / relay mode. The NTN can also include one or more client nodes, also known as user nodes (UEs). For example, the network can include a UE. This UE can be a terrestrial UE located at the ground level. The UE can include, for example, a mobile phone or IoT device.

[0065] Before describing example embodiments of the present disclosure in detail, it is necessary to briefly introduce some example general aspects of discontinuous reception (DRX) or extended DRX (eDRX) related behaviors, which may be helpful for understanding the present disclosure.

[0066] Broadly speaking (e.g., in some previous 3GPP releases), a UE configured with eDRX settings may be allowed to enter sleep mode for a longer period of time (e.g., compared to a regular DRX configuration). When such a UE wakes up and monitors a paging time window (PTW), it must typically monitor consecutive paging occasions based on the DRX settings. This means that the UE is configured with both eDRX and DRX settings, where the DRX settings are used when the UE wakes up from eDRX, as will be understood and appreciated by those skilled in the art.

[0067] Taking this behavior into account, 3GPP TS 38.133 then establishes, for example, how many measurements a UE must collect from the serving cell during one PTW in order to assess the suitability of the cell the UE is camped on (sometimes also referred to as the so-called "S criterion"), as follows:

[0068] The potential issues briefly described above roughly indicate that similar behavior must be applied when waking up earlier, K seconds before the start of the t-service, rather than waiting for the eDRX cycle to complete. However, as mentioned above, the incoming cell (target cell) may not be available K seconds before the start of the t-service, making this early wake-up both ineffective and inefficient.

[0069] For ease of understanding, please refer to Figure 1A 、 1B , 2A and 2B. Among them, Figure 1A and 1B Two exemplary (non-limiting) scenarios 1A and 1B are schematically shown, respectively, to illustrate possible temporal relationships between an old (current serving) cell and a new (incoming target) cell. Figure 2A and 2B Schematically shows the Figure 1A and 1B 1A and 1B for two exemplary signaling / messaging flow diagrams 100 and 200 for two exemplary scenarios 1A and 1B.

[0070] Generally speaking, Figure 1A (Case 1A) schematically illustrates a scenario where the time at which the current serving cell (e.g., a quasi-Earth-fixed cell associated with a corresponding satellite) will stop serving the current area (e.g., due to satellite movement) is (substantially) the same as, or earlier than, the time at which the new / target cell (associated with an incoming satellite) will become available (start serving the current area). Figure 1A That is, in some possible cases (although Figure 1A Not explicitly shown in the example), the new cell will also only be available sometime after t-service, or in other words, there may be a (time) gap between the respective services of the old and new cells. Figure 1B (Case 1B) schematically illustrates a scenario where the serving cell and the target cell have a certain cell overlap period (before the current serving cell will stop serving the current area as indicated by t-service). Broadly speaking, according to example embodiments of the present disclosure (as described in more detail below), in Figure 1A and 1B In either case, the UE will be configured to defer measurements on the target cell for a certain amount of time / period, thereby helping the UE save energy by avoiding useless measurements when the target cell is not yet available in the UE's area. This can greatly improve the efficiency of the entire communication system.

[0071] More specifically, if Figure 2AAs shown in step S101 of FIG, the UE may receive a suitable message from the serving cell, which includes information indicating the availability of the target cell (e.g., information about or related to the t-service of the serving cell). As shown in step S104, the serving cell (satellite) will stop providing service to the UE (S103) in its current serving area at the time indicated by t-service. The time indicated by t-service is Figure 2A In this example (which is the same as Figure 1A is slightly different from what is shown in , as mentioned above, Figure 1A The current serving cell in the target area stops serving the current area at (more or less) the same time as the new / target cell becomes available) earlier than the time at which the target cell (satellite) will become available (e.g. by broadcasting the necessary reference signals, as exemplarily shown in step S105). Therefore, the UE may be configured to determine a measurement-related behavior of the UE corresponding to the target cell (or in simple terms, target cell measurement behavior), which may in particular involve postponing measurements on the target (S102), adjusting measurement-related configurations (e.g., DRX-related configurations, or more specifically, DRX cycle configurations), and starting measurements (S106). It is worth noting that possible implementations related to such target cell availability indication (S101) and such UE behavior (S102 and S106) will be described in more detail below. On the other hand, in Figure 2B In the example scenario 2B shown, the target cell becomes available (using S203 and S204 as an example) before the t-service (S206) of the serving cell ends. In this case, the UE can be configured to adjust measurement-related behavior or be configured (e.g., DRX-related configuration) and start measurement (S205) before the serving cell stops serving (e.g., due to satellite movement).

[0072] It is worth noting that among other possible cases, so-called secondary DRX groups can be configured, which in general may allow different DRX settings (e.g. in terms of DRX on duration and inactivity timer) to be set for different serving cells (e.g. for carrier aggregation).

[0073] However, it remains to be noted that since the secondary DRX group typically shares the DRX cycle configuration with the primary DRX group, simply switching to a secondary DRX group configuration typically does not change the UE's measurement requirements, which only depend on the configured DRX cycle.

[0074] Given this, as previously mentioned, the present disclosure generally addresses the issue of target cell measurements in EFC scenarios when the target cell is available only shortly before or after the t-service of the current serving cell. Notably, this deployment can reduce the number of satellites required and, in principle, also cover discontinuous coverage. Broadly speaking, as will be clarified in the following description, the present disclosure generally encompasses two new aspects: a network indication of target cell availability and a corresponding change in UE measurement behavior.

[0075] Now refer to Figure 3 , which schematically illustrates a high-level example flow chart 300 of UE behavior according to some example embodiments of the present disclosure. It is noteworthy that the expression "conservative neighbor / target cell measurement requirement" used throughout the present disclosure (and in the accompanying figures) can be understood to generally refer to the required UE behavior as described above, namely, that a UE configured with eDRX settings must meet the DRX setting requirement (at least) K seconds before t-service. On the other hand, when the "conservative requirement" is not applied, an eDRX setting or a DRX setting with a longer DRX cycle than the "conservative measurement requirement" may still be considered applicable during the time interval [t-service-K, t-service]. It is noteworthy that, in some possible implementations, such eDRX or DRX (with a longer DRX cycle) setting may even be applied after t-service, for example, until the UE determines (e.g., selects) a target cell (e.g., after performing measurements).

[0076] Specific as Figure 3 As shown, a UE may receive (block 301) information from a network node (e.g., a gNB, etc.) indicating the availability of a target cell related to the timing at which a serving cell will stop serving its currently serving area. The timing at which a serving cell will stop serving its currently serving area may be indicated or determined by any suitable means (e.g., a preconfigured or predefined parameter), such as the t-service of the serving cell described above. Those skilled in the art will understand and appreciate that such indication information may be sent from the network node and received by the UE in any suitable message format. For example (but not limitation), such indication information may be received (or obtained) in a broadcast message, a higher layer (e.g., Radio Resource Control (RRC)) message, a UE-assisted DRX configuration (e.g., as part of a Medium Access Control (MAC) message), or even a combination thereof. In some possible implementations, the UE may also receive corresponding configuration (e.g., measurement-related configuration, such as DRX-related configuration) from the network node in the same message as the indication information or as a separate message, as will be understood and appreciated by those skilled in the art.

[0077] The information indicating the target cell's availability (related to the timing at which the serving cell will stop serving the area it currently serves, e.g., indicated by t-service) can be implemented in any suitable manner depending on various circumstances and / or requirements. Two possible example implementations will be discussed below for illustrative purposes only (and should not be construed as limiting in any way).

[0078] Option 1: Signage.

[0079] In this scenario, the network can be configured to provide a simple flag-like indication to indicate the applicability / availability of neighbor (incoming target) cell measurements. Those skilled in the art will appreciate that such flag indication can be implemented in any suitable form, such as a Boolean flag (e.g., "true" or "false"), a binary flag (e.g., "0" or "1"), a bit flag, or a bitmap.

[0080] Specifically, according to various implementations and / or requirements, the suitability / availability of the target cell (satellite) may be indicated in an explicit or implicit manner through such flag indication.

[0081] For example, in some possible implementations, the flag indication may be implemented as a simple availability bit (flag) indication, such that, for example, a true / false flag (or a similar flag as described above) configured at the SIB / RRC level may be understood as informing the UE of the target cell availability coverage K seconds (here, K may be understood as being greater than (or equal to) 0 in some possible cases) or longer before the start of the t-service.

[0082] In some other possible implementations, the flag indication can be implemented as a requirement bit / flag indication. This implementation is more or less the same as the above implementation, but instead of (explicitly) notifying the UE of target cell availability, the network can use this requirement indication flag to instruct (inform) the UE whether to apply a DRX-related configuration that meets the UE's predefined measurement requirements (e.g., the "conservative neighbor cell measurement requirement" described above). For example, in some possible implementations, this requirement indication flag can indicate that the conservative neighbor cell measurement requirement does not apply.

[0083] In some further possible implementations, an indication of the application of a low-power mode (sometimes also referred to as a power-saving mode) may be implemented. Typically, some UEs (e.g., deployed in IoT networks) may be configured with a power-saving mode (e.g., to extend battery life). In such cases, such an implementation may be considered applicable or appropriate, such that conservative neighbor cell measurements may be disabled for a UE (upon receipt of such a low-power mode flag indication) when the UE is configured to maximize power conservation. Optionally, particularly in such a low-power mode / configuration, some other possible UE features may also be disabled, thereby further extending the UE's usefulness in certain deployment scenarios.

[0084] In some possible implementations similar to the low-power mode implementation described above, such a flag indication may be used to indicate a so-called "relaxed measurement" configuration or requirement. Specifically, those skilled in the art will appreciate that, according to certain specifications / standards (e.g., 3GPP TS 38.133, etc.), relaxed measurements may be configured for UEs in idle / inactive mode. The conditions for triggering relaxed measurements may be based on the UE meeting at least one of the criteria of being considered "not at the cell edge" or "stationary." Therefore, upon receiving such a (relaxed measurement) indication flag, the UE may utilize the corresponding relaxed measurement configuration, which in turn may implicitly indicate that conservative neighbor cell measurement requirements are disabled (similar to the case of the power saving mode indication described above). For the sake of completeness, it is worth noting that, in some possible implementations, applying a low-power mode or relaxed measurement requirement / configuration may correspond to a different DRX configuration (e.g., a longer DRX cycle) and / or fewer measurement samples within a certain time window, depending on various circumstances and / or requirements.

[0085] On the other hand, generally speaking, a UE that receives such a flag indicating that the requirement is not applicable (e.g., according to any of the embodiments shown above) can be configured to maintain the (current) eDRX settings (e.g., the currently configured DRX cycle) and requirements for the time interval before t-service. In addition, in the case that the target cell will be available after t-service, this flag indication can also trigger the UE to apply conservative neighbor cell measurement requirements after t-service.

[0086] Option 2: Time indication.

[0087] In this scenario, compared to the flag indication in Option 1, the network can be configured to (explicitly or implicitly) inform the UE of the timing of the coverage availability of the incoming target cell (satellite). According to various embodiments, this timing can be indicated in any suitable manner, for example, in the form of (absolute or relative) seconds with reference to a predefined timing reference (e.g., t-service), the number of DRX cycles relative to t-service, in the form of frame and / or time slot numbers, etc., which can be understood and appreciated by those skilled in the art.

[0088] In some possible implementations, upon receiving such a time indication of the coverage availability of the target cell, the UE may be configured to evaluate (e.g., determine by calculation) whether the coverage availability of the incoming target cell / satellite occurs before or after the triggering time of t-service-K (where K may be a value greater than 0 (or equal to 0 in some possible cases). If it is determined that the target cell will be available before that point in time (t-service-K), the conservative requirement as described above may be applied to the UE. Depending on various implementations and / or requirements, the conservative requirement may, for example, be applied immediately, applied at time K, or deferred until the target cell becomes available. On the other hand, if it is determined that the coverage availability of the target cell will occur after this point in time, the following possible cases may be applied depending on various situations and / or requirements.

[0089] For example, in certain possible cases, the UE may be configured to simply not apply the conservative neighbor cell measurement requirement if the coverage availability of the incoming satellite occurs after t-service-K.

[0090] Additionally or alternatively, the UE may be configured to dynamically adjust DRX-related configurations (e.g., DRX cycle settings) during the time interval from t-service-K to t-service, such that the UE is able to monitor (or at least attempt to measure) at least a minimum number of measurements (e.g., defined by the specification / standard) from neighboring cells before t-service.

[0091] For ease of understanding, as an illustrative (non-limiting) example, a DRX cycle length of 2.56 seconds can be assumed for conservative measurement requirements. Therefore, such a DRX cycle could mean (according to the specification / standard) that the UE must be able to detect a (neighboring) cell within 23 measurements (e.g., a maximum of 58.88 seconds). However, in this example scenario, it can be assumed that the network has indicated (according to a time indication implementation) that an incoming neighbor cell is only available 35 seconds before the t-service of the current serving cell. Therefore, to avoid situations where these requirements do not apply, the UE must be able to be configured to (at least temporarily) select or determine one of the other (e.g., shorter) DRX cycle lengths in order to detect incoming neighbor cell measurements (e.g., by waking up more frequently). For example, based on the above assumptions, the UE could be specifically configured with a shorter DRX cycle that enables it to obtain at least 23 measurements within 35 seconds (instead of 58.88 seconds). Depending on various implementations and / or requirements, the selection or determination of such alternative DRX-related configurations may be left to the UE implementation, or guided by specifications / standards (e.g., by specifying that "a maximum [minimum] DRX cycle length must be selected that still allows the UE to detect the target cell."). Alternatively, in some other possible implementations, the network (or specification) may define the minimum number of samples that the UE must obtain for the target cell. Of course, those skilled in the art will understand and appreciate that any other suitable approach may also be implemented.

[0092] Note that it is worth mentioning that in some possible cases the UE may be configured to determine (e.g. based on a received timing indication) that the coverage availability of the incoming satellite will occur after t-service (this can also be seen as the case where K is equal to 0).

[0093] In this scenario, for example, the UE can be configured to adopt a shorter DRX cycle configuration so that it can measure the target cell more quickly after t-service, as the serving cell will have disappeared by then. Depending on various implementations and / or requirements, the UE can be configured to fall back to a certain (e.g., preconfigured or predefined) DRX cycle, for example, based on conservative requirements; or the network can be configured to set (or define) an absolute upper limit on the time for detection and evaluation after t-service (e.g., without explicitly defining a DRX cycle). Of course, those skilled in the art will understand and appreciate that any other suitable approach may also be implemented.

[0094] It is also worth noting that Options 1 and 2 above are not necessarily mutually exclusive, and in certain possible implementations, they may be used in conjunction. For example, the time indication of Option 2 may be used to convey timing information regarding the availability of the target cell, while the flag indication of Option 1 may be used to convey other information, such as a requirement indication, a low power mode, or a relaxed measurement mode indication, etc. Of course, those skilled in the art will also understand and appreciate that, depending on various circumstances and / or requirements, any other suitable means for indicating the availability of the target cell regarding the timing at which the serving cell will stop serving the area it currently serves (e.g., indicated by t-service) may also be implemented.

[0095] Considering the possible implementation of the target cell availability indication above, and returning to Figure 3 Upon receiving such an availability indication, the UE may be configured to determine (block 302) whether the target cell will be available before the service of the current serving cell ends (indicated by t-service). If it is determined that the target cell will not be available before t-service, the UE may be configured to defer target cell measurement until the target cell becomes available (block 304). In some possible implementations, as exemplified in block 304, the UE may also be configured to adjust a DRX-related configuration or a portion thereof (e.g., the DRX cycle configuration) and / or the number / amount of samples to be monitored or collected for target cell measurement (e.g., the minimum number / amount of samples) so that the UE can monitor or at least attempt to measure a reasonable number of samples within a short period of time. The reason behind this adjustment can be understood as follows: since the current serving cell will be out of service (at t-service), but the new cell will not be available at that time (block 302: "No"), the UE urgently needs to find the target cell to maintain service continuity (i.e., to be able to continue communication). Those skilled in the art will understand and appreciate that the longer the UE is deferred for target cell measurement, the more quickly (and more efficiently) the UE needs to be able to find the new incoming cell to camp on. The DRX related configuration or parts thereof (eg, DRX cycle configuration) and / or the number / amount of samples to be monitored or collected for target cell measurements must be adjusted accordingly (eg, shorter DRX cycle length, more measurement samples, etc.).

[0096] On the other hand, if it is determined that the target cell will be available before t-service ("yes" in block 302), the UE may also be configured to determine (block 305) whether the timing at which the target cell will be available is also known (e.g., depending on whether the network node sends a time indication, as shown in option 2 above).

[0097] If the answer is "yes", the UE may be configured to defer measurements until the target cell is available (block 306), similar to that shown with reference to block 303. Furthermore, in this case, in some possible implementations, the UE is additionally configured to determine (block 307) whether the target cell will be available before "t-service-K" (corresponding to the conservative measurement requirement as shown above). If it is determined that the target cell will indeed be available before the time indicated by t-service-K ("yes" in block 307), the UE may be configured to perform measurements based on the DRX-related configuration (e.g., the specified / configured DRX cycle length) according to the conservative neighbor cell measurement requirement (block 308), for example, immediately, at time K, or deferred until the target cell is available, depending on various implementations and / or requirements. On the other hand, if it is determined that the target cell will not be available before the time point indicated by t-service–K (“No” in block 307 , but still before t-service in this example), the UE may be configured (similar to block 304 ) to determine (e.g., adjust) a DRX-related configuration or part thereof (e.g., a DRX cycle configuration) and / or a number / amount of samples to be monitored or collected for target cell measurements (e.g., a minimum number / amount of samples) (block 309 ).

[0098] Furthermore, in the event that the timing of target cell availability is unknown ("No" in block 305), for example because the network node has not communicated a time indication, the UE may be configured to start measurements (block 310). It is worth noting that in some possible alternative implementations, it is still possible that the UE may receive (block 311) information from the network, for example, at any appropriate time during the process, that explicitly indicates whether such conservative neighbor cell measurement requirements should be applied. Upon receiving such direct / explicit indication or instruction, the UE will proceed accordingly, as exemplified in blocks 312 (apply conservative neighbor cell measurement requirements) and 313 (apply current (e)DRX cycle configuration), respectively.

[0099] It is worth noting that in some other possible implementations (although not explicitly shown in the figure), the network can be configured to instruct / command the UE to activate the secondary DRX configuration, for example, by transmitting appropriate indication information (e.g., a flag indication as shown above). In this case, the secondary DRX configuration can be configured (by the network node) to have a different DRX-related configuration (e.g., a shorter DRX cycle), thereby causing the UE to perform more frequent measurements on potential neighboring target cells. In some possible implementations, the secondary DRX configuration can also be used to convey or define the time when the target cell is available (similar to the time indication described above), or any other suitable information that will be understood and appreciated by those skilled in the art.

[0100] In some further possible implementations, the UE may be configured to allow adjustment (e.g., relaxation) of target cell measurements only when the UE is not at a cell edge or in a low mobility state, in conjunction with receiving a recommended network indication (e.g., a flag and / or time indication as described above) (e.g., a state specified in a specification / standard).

[0101] In summary, the present disclosure generally addresses the issue of target cell measurement in EFC scenarios when the target cell is available only shortly before or after the t-service of the current serving cell. Specifically, as detailed above, it is generally proposed that the network be configured to provide an indication of the target cell's availability relative to the t-service of the current serving cell. Depending on the implementation and / or requirements, this indication may be a flag / bit that explicitly or implicitly indicates or conveys (explicitly or implicitly) that the target cell will be available before / after the t-service (or any other suitable information as described above); or it may be a value indicating the time before / after the target cell will be available. As will be understood and appreciated by those skilled in the art, this time may be an absolute time, a relative value relative to the t-service, a DRX cycle number relative to the t-service, or the like. As will be understood and appreciated by those skilled in the art, such an indication may be provided by the network to the UE via any of a system information broadcast (SIB) message, a higher-layer message (e.g., an RRC message), a medium access control (MAC) message (e.g., including a secondary DRX configuration), an application message, or the like.

[0102] Based on this indication, the UE can be configured to determine (e.g., adjust) its target cell measurement behavior accordingly. For example, in some of the possible (non-limiting) scenarios described above, if the indication indicates that the target cell is not available in advance, the UE can be configured to defer target cell measurements until t-service. In other possible (non-limiting) scenarios, the UE can be configured to adjust measurements only for cells with the same satellite ephemeris as the target cell, any cells with different satellite ephemeris than the serving cell, or measurements related to a specific cell (i.e., a target cell that replaces the current cell). Furthermore, the UE can be configured to adhere to different measurement requirements based on this indication. For example, requirements for a specific frequency (corresponding to the frequency of the target cell) can be adjusted with respect to required measurement delay and accuracy. Additionally or alternatively, the UE can be configured to adhere to requirements corresponding to a different (e.g., network-configured) DRX cycle, which can be the same as or different from the UE's currently applied DRX cycle.

[0103] According to the configurations suggested in the exemplary embodiments of the present disclosure, the UE's target cell measurement behavior can be efficiently and flexibly controlled, thereby helping the UE save energy, particularly by avoiding performing invalid measurements (e.g., when the target cell is unavailable in the UE's area). It is also worth noting that, when the (flag / time) indication is conveyed via SIB messaging, the need to reconfigure the DRX cycle for all RRC Idle / Inactive UEs in the cell at each cell handover can be avoided, thereby improving the efficiency of the entire communication system.

[0104] For the sake of completeness, it is still necessary to note that although in the above-mentioned example embodiments (with reference to the accompanying drawings), the messages communicated / exchanged between the network node and the UE may appear to have specific / clear names and / or contents included therein, according to various implementations (e.g., the emphasized techniques), these messages may have different names, contents and / or be communicated / exchanged in different forms / formats, as can be understood and appreciated by those skilled in the art.

[0105] According to some example embodiments, corresponding methods are also provided, which are suitable for being performed by an apparatus (network element / component) as described above (e.g., a UE, a serving and / or target network node (e.g., a gNB, etc.)).

[0106] It should also be noted that the above-mentioned apparatus (or system) features correspond to corresponding method features, however, for the sake of brevity, these method features may not be explicitly described. The disclosure of this application is also considered to extend to such method features. Specifically, the disclosure should be understood to relate to methods of operating the above-mentioned apparatus, and / or to providing and / or arranging the various units of these apparatuses.

[0107] In addition, according to some further example embodiments, a corresponding apparatus (for example, implementing the UE, (serving) network node, etc. as described above) is also provided, which includes at least one processing circuit and at least one memory for storing instructions executed by the processing circuit, wherein the at least one memory and the instructions are configured to, together with the at least one processing circuit, enable the corresponding apparatus to at least perform the corresponding steps described above.

[0108] Figure 4An exemplary (non-limiting) example of such an apparatus 400 is schematically shown. The apparatus 400 can be configured to implement the UE or serving network node (cell) proposed in this disclosure. In some possible scenarios, the apparatus 400 can also be implemented as any network node / component / unit suitable for a communications system, for example, a station coupled to and / or used to control an access system, such as a RAN node (e.g., a base station, eNB, or gNB), a relay node or core network node (e.g., an MME, S-GW, or P-GW), a core network function (e.g., an AMF / SMF), a server or host, or, in some possible embodiments, a UE. According to various embodiments, the methods described in this disclosure can be implemented in a single apparatus or across multiple apparatuses. The apparatus can be integrated with a node or module of a core network, RAN, or the like, or located externally thereto. Specifically, the apparatus 400 can be used to control communications within a service area of ​​the system. The apparatus 400 may include at least one memory 401, at least one data processing unit (or circuit) 402, 403, and an input / output interface 404. The apparatus 400 may be coupled to any other suitable components of the apparatus 400 (e.g., a receiver and / or transmitter), or to any other suitable apparatus, via the interface 404. In some possible examples, the receiver and / or transmitter may be implemented as a radio front end or a remote radio head, depending on various implementations and / or circumstances.

[0109] In some other example embodiments, a corresponding apparatus (eg, a UE or a network node implementing the above-described apparatus, etc.) is provided, which includes corresponding components configured to at least perform the above-described corresponding steps.

[0110] It should be noted that the examples of the embodiments of the present disclosure are applicable to a variety of different network configurations. In other words, the examples shown in the above figures (which serve as the basis for the above examples) are merely illustrative and do not limit the present disclosure in any way. That is, based on the defined principles, additional, further existing and proposed new functionality available in the corresponding operating environment can be used in conjunction with the examples of the embodiments of the present disclosure.

[0111] It should also be noted that the disclosed example embodiments can be implemented in a variety of ways using hardware and / or software configurations. For example, the disclosed embodiments can be implemented using dedicated hardware and / or hardware in combination with software executable thereon. The components and / or units shown in the figures are merely examples and do not limit the scope of use or functionality of any hardware, combination of software and hardware, firmware, embedded logic components, or combination of two or more such components to implement specific embodiments of the present disclosure.

[0112] It should also be noted that the description and drawings illustrate only the principles of the present disclosure. Those skilled in the art will be able to implement various arrangements that, although not explicitly described or shown herein, embody the principles of the present disclosure and are within its spirit and scope. In addition, all examples and embodiments summarized in this disclosure are primarily for illustrative purposes only to help the reader understand the principles of the proposed methods. Moreover, all statements herein providing principles, aspects, and embodiments of the present disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof.

Claims

1. A user equipment (UE), served by a serving cell of a network node and configured to support communications over a non-terrestrial network (NTN), the UE comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least perform the following operations: receiving, from the network node, information indicating availability of a target cell related to a timing at which the serving cell will stop serving an area that it is currently serving; determining, based on the received information, availability of the target cell in relation to the timing at which the serving cell stops serving the area currently served by the serving cell; determining, based on the determined availability of the target cell, a measurement-related behavior of the UE corresponding to the target cell; as well as Perform measurement on the target cell according to the determined measurement-related behavior.

2. The UE according to claim 1, wherein: Based on determining that the target cell will be unavailable before the timing at which the serving cell will stop serving the area currently served, determining the measurement-related behavior of the UE corresponding to the target cell involves at least one of the following: deferring the execution of the measurement on the target cell until the timing at which the serving cell will stop serving the area currently served by the serving cell; and A discontinuous reception, DRX, related configuration is applied, wherein the DRX cycle is shorter than the cycle currently configured on the UE.

3. The UE according to claim 1 or 2, wherein: The information indicating the availability of the target cell includes flag information, where the flag information indicates at least one of the following: whether the target cell will be available before the serving cell stops serving the area it currently serves; whether the target cell will be available at least K seconds before the serving cell stops serving the area it currently serves, where K is a preconfigured value greater than 0; whether to apply a DRX-related configuration that meets the predefined measurement requirements of the UE; whether to apply the low power consumption mode configuration of the UE; or Whether to apply the relaxed measurement configuration of the UE.

4. The UE according to any one of the preceding claims, wherein: The information indicating the availability of the target cell includes time information indicating when the target cell will be available. The UE according to claim 4 , wherein: Based on a determination that the target cell is available before the serving cell will stop serving the area currently served by the serving cell, determining the measurement-related behavior of the UE corresponding to the target cell involves: The execution of the measurement on the target cell is postponed until a timing when the target cell will be available.

6. The UE according to claim 4 or 5, wherein: Determining the availability of the target cell in relation to the timing at which the serving cell stops serving the area currently served includes: determining, based on the received time information, whether the target cell will be available at least K seconds before the serving cell stops serving the area currently served, where K is a preconfigured value greater than or equal to 0; Wherein, based on a determination that the target cell will be available at least K seconds before the serving cell stops serving the area currently served, determining the measurement-related behavior of the UE corresponding to the target cell involves: applying a DRX-related configuration that meets predefined measurement requirements of the UE; and Wherein, based on the determination that the target cell will be unavailable at least K seconds before the serving cell stops serving the area currently served, determining the measurement-related behavior of the UE corresponding to the target cell involves at least one of the following: maintaining the current measurement-related configuration of the UE, or The DRX-related configuration of the UE is adjusted during the K seconds before the serving cell stops serving the area it currently serves to enable the UE to monitor at least a preconfigured amount of measurements from neighboring cells.

7. A UE according to any one of the preceding claims, wherein: The information indicating the availability of the target cell is received in at least one of the following: a broadcast message, a higher layer message, or information of a assisted DRX configuration configured for the UE.

8. A UE according to any one of the preceding claims, wherein: The timing at which the serving cell will stop serving the area it is currently serving is determined based on pre-configured parameters received by the UE from the network node.

9. A network node configured to support communication with a user equipment (UE) served by a serving cell of the network node over a non-terrestrial network (NTN), the network node comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the network node to at least: determining the availability of a target cell relative to a timing at which the serving cell will stop serving an area it currently serves; and Information indicating availability of the target cell is sent to the UE.

10. The network node according to claim 9, wherein: The information indicating the availability of the target cell includes: Flag information indicating at least one of the following: whether the target cell will be available before the serving cell stops serving the area it currently serves, whether the target cell will be available at least K seconds before the serving cell stops serving the area it is currently serving, where K is a preconfigured value greater than 0, whether to apply DRX-related configurations that meet the predefined measurement requirements of the UE, Whether to apply the low power mode configuration of the UE, or whether to apply the relaxed measurement configuration of the UE; and / or Time information indicating when the target cell will be available.

11. The network node according to claim 9 or 10, wherein: The information indicating the availability of the target cell is sent to the UE via at least one of: a broadcast message, a higher layer message, or a assisted DRX configuration of the UE.

12. A method for a user equipment (UE), wherein the UE is served by a serving cell of a network node and is configured to support non-terrestrial network (NTN) communications, the method comprising: receiving, from the network node, information indicating availability of a target cell related to a timing at which the serving cell will stop serving an area that it is currently serving; determining, based on the received information, availability of the target cell in relation to the timing at which the serving cell stops serving the area currently served by the serving cell; determining, based on the determined availability of the target cell, a measurement-related behavior of the UE corresponding to the target cell; as well as Perform measurement on the target cell according to the determined measurement-related behavior.

13. A method of a network node configured to support communication with a user equipment (UE) served by a serving cell of the network node over a non-terrestrial network (NTN), the method comprising: determining availability of a target cell in relation to a timing at which the serving cell will stop serving an area currently served by the serving cell; as well as Information indicating availability of the target cell is sent to the UE.

14. A computer program comprising instructions for causing an apparatus to perform the method according to claim 12.

15. A computer program comprising instructions for causing an apparatus to perform the method according to claim 13.

16. A memory storing computer-readable instructions for causing a device to execute the method according to claim 12.

17. A memory storing computer-readable instructions for causing a device to execute the method according to claim 13.

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