Obtaining new satellite assistance information for satellite handover

Abstract

The invention relates to obtaining new satellite assistance information for satellite handover. A method is provided that includes scheduling transmission of a system information block (SIB) including an information element having auxiliary information for a first aerospace platform and a separate at least one information element having auxiliary information for a second aerospace platform. The first aerospace platform and the second aerospace platform are configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-earth fixed cells serving a geographic area for a limited period of time. The method further comprises causing the user equipment in the first NTN cell to obtain, during a period in which the geographic area is served by the first NTN cell, at least one separate information element having assistance information for the second aerospace platform before the geographic area is served by the second NTN cell.

Description

Technical Field

[0001] The present disclosure relates generally to telecommunications, and in particular, to satellite handover in a non-terrestrial network (NTN) of a telecommunications system. Background Art

[0002] A telecommunication system may be considered as a facility that enables communication sessions between two or more entities (e.g., user terminals, base stations, and / or other nodes) by providing carrier waves between the various entities involved in the communication path. A telecommunication system may be provided, for example, with the aid of a communication network and one or more compatible communication devices. A communication session may include, for example, communications for carrying data for communication (e.g., voice, video, email, text messaging, multimedia and / or content data, etc.). Non-limiting examples of services provided include two-way or multi-way calls, data communications or multimedia services, and access to data network systems (e.g., the Internet).

[0003] In a wireless telecommunication system, at least a portion of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems include public land mobile networks (PLMNs), satellite-based communication systems, and different wireless local networks, such as wireless local area networks (WLANs). Some wireless systems may be divided into cells, and are therefore often referred to as cellular systems.

[0004] A user can access a telecommunication system by means of an appropriate communication device or terminal. The user's communication device may be referred to as a user equipment (UE) or user device. The communication device is equipped with appropriate signal receiving and sending devices to achieve communication, such as access to a communication network or direct communication with other users. The communication device can access a carrier provided by a station (e.g., a base station of a cell) and send and / or receive communications on the carrier.

[0005] Telecommunication systems and associated equipment typically operate according to a given standard or specification, which sets out what the various entities associated with the system are allowed to do and how it should be achieved. Communication protocols and / or parameters that should be used for the connection are also typically defined. An example of a telecommunication system is the Universal Mobile Telecommunications System (UMTS). Other examples of telecommunication systems are Long Term Evolution (LTE), Advanced LTE, and so-called 5G or New Radio (NR) networks. NR is being standardized by the Third Generation Partnership Project (3GPP). Summary of the invention

[0006] Example implementations of the present disclosure relate to telecommunications, and in particular, to satellite handover in a non-terrestrial network (NTN) of a telecommunications system.In this regard, the present disclosure includes, but is not limited to, the following example implementations.

[0007] Some example implementations provide an apparatus comprising: at least one memory configured to store a computer-readable program code; and at least one processing circuit configured to access the at least one memory and execute the computer-readable program code so that the apparatus at least: schedules transmission of a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-geo-fixed cells serving a geographic area within a limited period of time; and causes a user equipment in the first NTN cell to obtain the separate at least one information element having the assistance information for the second aerospace platform before the geographic area is served by the second NTN cell and during the period of time when the geographic area is served by the first NTN cell.

[0008] Some example implementations provide an apparatus comprising: a component for scheduling transmission of a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-earth fixed cells serving a geographic area within a limited period of time; and a component for enabling a user equipment in the first NTN cell to obtain the separate at least one information element having the assistance information for the second aerospace platform before the geographic area is served by the second NTN cell and during the period when the geographic area is served by the first NTN cell.

[0009] Some example implementations provide an apparatus comprising: at least one memory configured to store a computer-readable program code; and at least one processing circuit configured to access the at least one memory and execute the computer-readable program code so that the apparatus at least: receives scheduling information for a system information block SIB at a user equipment, the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network NTN cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area within a limited period of time; and obtains the separate at least one information element having the assistance information for the second aerospace platform at the user equipment in the first NTN cell before the geographic area is served by the second NTN cell and during the period of time when the geographic area is served by the first NTN cell.

[0010] Some example implementations provide an apparatus comprising: a component for receiving, at a user equipment, scheduling information for a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-earth fixed cells serving a geographic area within a limited period of time; and a component for obtaining, at the user equipment in the first NTN cell, the separate at least one information element having the assistance information for the second aerospace platform, before the geographic area is served by the second NTN cell and during the period of time when the geographic area is served by the first NTN cell.

[0011] Some example implementations provide a method, including: scheduling transmission of a system information block (SIB), the SIB including an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-earth fixed cells serving a geographic area within a limited period of time; and enabling a user equipment in the first NTN cell to obtain the separate at least one information element having the assistance information for the second aerospace platform before the geographic area is served by the second NTN cell and during the period when the geographic area is served by the first NTN cell.

[0012] Some example implementations provide a method, comprising: receiving, at a user equipment, scheduling information for a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-earth fixed cells serving a geographic area within a limited period of time; and obtaining, at the user equipment in the first NTN cell, the separate at least one information element having the assistance information for the second aerospace platform, before the geographic area is served by the second NTN cell, during the period of time when the geographic area is served by the first NTN cell.

[0013] Some example implementations provide a computer-readable storage medium that is non-transitory and stores therein a computer-readable program code that, in response to being executed by at least one processing circuit, causes an apparatus to at least: schedule transmission of a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-earth fixed cells serving a geographic area within a limited period of time; and cause a user equipment in the first NTN cell to obtain the separate at least one information element having the assistance information for the second aerospace platform before the geographic area is served by the second NTN cell and during the period when the geographic area is served by the first NTN cell.

[0014] Some example implementations provide a computer-readable storage medium that is non-transitory and stores therein a computer-readable program code that, in response to being executed by at least one processing circuit, causes an apparatus to at least: receive scheduling information for a system information block (SIB) at a user equipment, the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells that serve a geographic area within a limited period of time; and obtain, at the user equipment in the first NTN cell, the separate at least one information element having the assistance information for the second aerospace platform, before the geographic area is served by the second NTN cell, during the period of time when the geographic area is served by the first NTN cell.

[0015] These and other features, aspects and advantages of the present disclosure will be apparent from reading the following detailed description and the accompanying drawings briefly described below. The present disclosure includes any combination of two, three, four or more features or elements set forth in the present disclosure, regardless of whether such features or elements are explicitly combined or otherwise detailed in the specific example implementations described herein. The present disclosure is intended to be read as a whole so that any separable features or elements in any aspect and example implementation of the present disclosure should be considered combinable, unless the context of the present disclosure explicitly indicates otherwise.

[0016] Therefore, it will be understood that this “Summary” is provided only to summarize some example implementations in order to provide a basic understanding of some aspects of the present disclosure. Therefore, it will be understood that the above-mentioned example implementations are only examples and should not be interpreted as narrowing the scope or spirit of the present disclosure in any way. Other example implementations, aspects and advantages will become apparent from the following detailed description in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of some of the described example implementations. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Having therefore described example implementations of the present disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0018] Figure 1 A telecommunications system including one or more public land mobile networks (PLMNs) coupled to one or more external data networks is shown according to some example implementations of the present disclosure;

[0019] Figure 2 illustrates a 5G deployment of a PLMN according to some example implementations;

[0020] Figure 3 Shown according to some examples of implementation Figure 2 Deployment of non-terrestrial networks (NTN) in 5G deployment;

[0021] Figure 4 An example of satellite switching in an NTN according to some example implementations is shown;

[0022] Figure 5 shows a timing diagram according to some example implementations;

[0023] Figure 6 is a flow chart showing various steps in a method according to some example implementations;

[0024] Fig. 7A , 7B , 7C, 7D and 7E are more descriptive flow charts showing various steps in the method from the perspective of a radio access node according to various example implementations;

[0025] Fig. 8A , 8B , 8C, 8D and 8E are more descriptive flow charts showing various steps in the method from the perspective of a user device according to various example implementations; and

[0026] Fig. 9 Apparatus according to some example implementations are shown. DETAILED DESCRIPTION

[0027] Some implementations of the present disclosure will now be described more fully below with reference to the accompanying drawings, in which some but not all implementations of the present disclosure are shown. In fact, various implementations of the present disclosure can be embodied in a variety of different forms and should not be construed as being limited to the implementations set forth herein. On the contrary, these example implementations are provided to make the present disclosure detailed and complete, and to fully convey the scope of the present disclosure to those skilled in the art. The same reference numerals always refer to the same elements.

[0028] Unless otherwise specified or clear from the context, references to first, second, etc. should not be construed as implying a particular order. A feature described as being above another feature (unless otherwise specified or clear from the context) may instead be below, and vice versa; and similarly, a feature described as being to the left of another feature may instead be to the right, and vice versa. Furthermore, although references may be made herein to quantitative measurements, values, geometric relationships, etc., unless otherwise specified, any one or more (if not all) of these may be absolute or approximate to take into account acceptable variations that may occur, such as variations due to engineering tolerances, etc.

[0029] As used herein, unless otherwise specified or clear from the context, an "or" of a set of operands is an "exclusive or" and is thus true if and only if one or more of the operands are true, whereas an exclusive or, in contrast, is false when all operands are true. Thus, for example, "[A] or [B]" is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. In addition, the articles "a" and "an" refer to "one or more" unless otherwise specified or clear from the context to refer to the singular. In addition, it should be understood that the terms "data," "content," "digital content," "information," and similar terms are sometimes used interchangeably unless otherwise specified. The term "network" may refer to a group of interconnected computers, including clients and servers; and within a network, these computers may be directly or indirectly interconnected by various means, including via one or more switches, routers, gateways, access points, etc.

[0030] Reference may be made herein to terminology specific to particular systems, architectures, etc., but it is understood that example implementations of the present disclosure may be equally applicable to any of a plurality of systems, architectures, etc. For example, reference may be made to 3GPP technologies such as Global System for Mobile Communications (GSM), UMTS, LTE, LTE-Advanced, and 5G NR; however, it is understood that example implementations of the present disclosure may be equally applicable to non-3GPP technologies such as IEEE 802, Bluetooth, and Bluetooth Low Energy.

[0031] In addition, as used in this application, the term "circuitry" may refer to one or more or all of the following: (a) a hardware circuit implementation only (e.g., an implementation in analog and / or digital circuits only); (b) a combination of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuits with software / firmware, and (ii) any portion of a hardware processor (including a digital signal processor) with software, software, and memory that work together to enable a device (e.g., a mobile phone or server) to perform various functions; or (c) a hardware circuit and / or processor, such as a microprocessor or a portion of a microprocessor, that requires software (e.g., firmware) to operate, but the software may not be present when the software is not required for operation.

[0032] The above definition of "circuitry" applies to all uses of the term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" also covers an implementation of only one hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its accompanying software and / or firmware. The term "circuitry" also covers (for example and if applicable to a particular claim element) a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0033] Figure 1 A telecommunications system 100 implemented according to various examples of the present disclosure is shown. A telecommunications system typically includes one or more telecommunications networks. As shown, for example, the system includes one or more public land mobile networks (PLMNs) 102, which are coupled to one or more other external data networks 104, particularly including a wide area network (WAN) such as the Internet. Each PLMN includes a core network (CN) 106 backbone, such as an evolved packet core (EPC) of LTE, a 5G core network (5GC), etc.; and each core network and the Internet are coupled to one or more radio access networks (RAN) 108, air interfaces, etc. that implement one or more radio access technologies (RATs). As used herein, "network equipment" refers to any suitable equipment on the network side of a telecommunications network. Examples of suitable network equipment are described in more detail below.

[0034] In addition, the system includes one or more radio units, which may be variously referred to as user equipment (UE) 110, terminal equipment, terminal preparation, mobile station, etc. A UE is generally a device configured to communicate with another UE in a network device or telecommunication network. A UE may be a portable computer (e.g., a laptop computer, a notebook computer, a tablet computer), a mobile phone (e.g., a cellular phone, a smart phone), a wearable computer (e.g., a smart watch), etc. In other examples, a UE may be an Internet of Things (IoT) device, an Industrial IoT (IIoT device), a vehicle equipped with vehicle-to-everything (V2X) communication technology, etc. In operation, these UEs may be configured to connect to one or more of the RAN 108 according to their specific radio access technology, thereby accessing a specific core network of the PLMN 102, or accessing one or more of the external data networks 104 (e.g., the Internet). The external data network may be configured to provide Internet access, operator services, third-party services, etc. For example, the International Telecommunication Union (ITU) has divided 5G mobile network services into three categories: enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and massive machine-type communications (mMTC) or massive Internet of Things (MIoT).

[0035] Examples of radio access technologies include 3GPP radio access technologies, such as GSM, UMTS, LTE, Advanced LTE, and 5G NR. Other examples of radio access technologies include IEEE 802 technologies, such as IEEE 802.11 (Wi-Fi), IEEE 802.15 (including 802.15.1 (WPAN / Bluetooth), 802.15.4 (Zigbee), and 802.15.6 (WBAN)), Bluetooth, Bluetooth Low Energy (BLE), Ultra-Wideband (UWB), etc. In general, radio access technology may refer to any 2G, 3G, 4G, 5G or higher generation mobile communication technology and different versions thereof, as well as any other wireless radio access technology that may be arranged to interwork with such mobile communication technology to provide access to the core network of a mobile network operator (MNO).

[0036] In various examples, the RAN 108 may be configured as one or more macro cells, micro cells, pico cells, femto cells, etc. The RAN may generally include one or more radio access nodes configured to interact with the UE 110. In various examples, the radio access node may be referred to as a base station (BS), an access point (AP), a base transceiver station (BTS), a node B (NB), an evolved NB (eNB), a macro BS, a NB (MNB) or an eNB (MeNB), a home BS, a NB (HNB) or an eNB (HeNB), a next generation NB (gNB), a next generation eNB (ng-eNB), etc. A certain type of network control / management entity is responsible for the control of the radio access node. The network control / management entity and the radio access node may be separate or integrated into a single device. The network control / management entity may include a processing circuit configured to perform various management functions, etc. The processing circuit may be associated with a computer-readable storage medium or a database for maintaining information required in the management function.

[0037] The RAN 108 may be centralized or distributed. In various examples, the components of the RAN may be interconnected by Ethernet, Gigabit Ethernet, Asynchronous Transfer Mode (ATM), fiber, dark fiber, passive wavelength division multiplexing (WDM), WDM-passive optical network (WDM-PON), optical transport network (OTN), time sensitive network (TSN), and / or any other data link layer network (possibly including radio links). The RAN may be connected to the CN 106 via one or more gateways, network functions, etc.

[0038] As will be appreciated, the PLMN 102 can be deployed in a number of different ways. In a 4G LTE deployment, the EPC is the CN 106, and the Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) is the RAN 108; and the E-UTRAN includes one or more eNBs (radio access nodes) configured to connect the UE 110 to the E-UTRAN and thereby access the EPC. Figure 2 As shown in , in 5G deployment 200, 5GC 202 is CN, and next generation (NG) radio access network (NG-RAN) 204 is RAN; and NG-RAN includes one or more gNBs 206 (radio access nodes) configured to connect UE 208 to NG-RAN, thereby accessing 5GC. The term "gNB" in 5G can correspond to eNB in ​​4G LTE.

[0039] Some 4G LTE and 5G deployments are considered standalone (SA) deployments. Other deployments combine 4G LTE and 5G technologies and are referred to as non-standalone (NSA) deployments. In some deployments, the E-UTRAN includes one or more ng-eNBs that are configured to communicate with the 5GC and may also be configured to communicate with one or more gNBs. Similarly, in another deployment, the NG-RAN may include one or more en-gNBs that are configured to communicate with the EPC and may also be configured to communicate with one or more eNBs.

[0040] In various instances, a single UE 110, 208 (dual mode or multi-mode UE) may support multiple (two or more) RANs and may be configured to connect to multiple RANs. For example, a particular UE may support both LTE and 5G NR radio access technologies. In this regard, various deployments support dual connectivity (DC) and in some specific examples support multi-radio dual connectivity (MR-DC), where the UE may be configured to connect to two different radio access nodes connected via a non-ideal backhaul, one radio access node providing NR access and the other radio access node providing E-UTRA or NR access.

[0041] In radio communications, node operations may be performed at least in part in a central / centralized unit (CU), such as a server, host, or node, which is operationally coupled to a distributed unit (DU) (e.g., a radio head / node). Node operations may also be distributed between multiple servers, hosts, or nodes. It should also be understood that the allocation of work between CN 106 operations and radio access node (RAN 108) operations may vary depending on the implementation. Therefore, the 5G network architecture may be based on so-called CU-DU separation. One gNB-CU (central node) may control one or more gNB-DUs. The gNB-CU may control multiple spatially separated gNB-DUs that act as at least transmit / receive (Tx / Rx) nodes. However, in some example implementations, a gNB-DU (also referred to as a DU) may include, for example, a radio link control (RLC), a media access control (MAC) layer, and a physical (PHY) layer, while a gNB-CU (also referred to as a CU) may include layers above the RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC), and an Internet Protocol (IP) layer. Other functional divisions are also possible. It is assumed that the skilled person is familiar with the OSI model and the functions within each layer.

[0042] In some example implementations, a server or CU may generate a virtual network through which the server communicates with the radio node. In general, a virtual network may involve the following process: combining hardware and software network resources and network functions into a single software-based management entity (virtual network). Such a virtual network may provide a flexible allocation of operations between the server and the radio head / node. In practice, any digital signal processing task may be performed in a CU or DU, and the boundaries for transferring responsibilities between the CU and DU may be selected based on the implementation.

[0043] Networks, including 5G, are now beginning to support non-terrestrial networks (NTNs). In an NTN system, a radio access node (e.g., gNB) or radio access node functionality can be deployed on a satellite or other aerospace platform in a regenerative deployment (or architecture), or relayed by a radio access node in a transparent deployment. As a result, NTNs can provide communication coverage over very large areas that may not be reachable via terrestrial radio access networks alone. This functionality can be used to connect IoT devices globally, as well as provide personal communications in remote areas and disaster relief.

[0044] Figure 3 Shown according to some examples of implementation Figure 2 300 of a deployment of an NTN 302 in a 5G deployment 200 of FIG. As shown, the NTN may include an aerospace platform (e.g., a satellite 304) connected to a UE 208 via a service link 306 (radio link) and connected to an NTN gateway 308 via a feeder link 310 (radio link). The NTN gateway may then be connected to a gNB. In some examples, the NTN gateway and the gNB may be co-located.

[0045] In various examples, the aerospace platform may be a satellite or airborne platform, an aircraft, etc. As shown, the aerospace platform may be a satellite 304. In other more specific examples, the aerospace platform may be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, a geostationary earth orbit (GEO) satellite, etc. Likewise, in more specific examples, the aerospace platform may be an unmanned aircraft system (UAS), such as a tethered UAS (TUA), a lighter-than-air UAS (LTA), a heavier-than-air UAS (HTA), a high altitude platform (HAP), etc. Some example implementations of the present disclosure may be described in the context of a satellite or a UAS, but it should be understood that these example implementations are equally applicable to other aerospace platforms.

[0046] In the specific example where the aerospace platform is a satellite 304 of the NTN 302 in a transparent deployment, the satellite can implement a transparent payload. That is, the satellite can implement radio frequency (RF) filtering, conversion, and amplification. Therefore, the waveform signal repeated by the payload can remain unchanged. The satellite can generate a radio coverage beam with a corresponding coverage area (footprint) 312 over a given service area defined by its field of view 314 and onboard antenna technology. The corresponding coverage area of ​​the radio beam is generally elliptical. The field of view of the satellite can depend on the onboard antenna diagram and / or the minimum elevation angle. One radio beam can carry the signal of one NR cell, and multiple satellite radio beams can carry the signals of a single NR cell or multiple NR cells.

[0047] In order to reduce the signaling overhead for the UE 208 and simplify the RRC procedures, the subject of an unchanging physical cell identifier (PCI) has been introduced. The working principle is that after the UE switches from one satellite to another, the serving gNB 206 (on the ground) does not change; and therefore, most of the cell configuration can be preserved without changing the PCI, frequency, and other cell configuration parameters. Then, the satellite handover can be almost transparent to the UE, without requiring the UE to perform Layer 3 (L3) mobility (i.e., handover procedures) or update its security keys.

[0048] Some conditions for enabling satellite handover without L3 mobility and with unchanged PCI or changed PCI may include: the NTN cell served by the satellite is deployed as a quasi-Earth Fixed Cell (EFC) serving a geographic area for a limited period of time. The network (e.g., gNB 206) may indicate to UE 208 how / when to perform downlink and uplink synchronization with the new satellite after the handover, or the network may accept an outage gap for the UE to detect and adapt the timing of the new satellite.

[0049] The recent focus is on transparent deployments (or architectures), including the case where NTN cells are provided by the same gNB 206. That is, the same cell with a fixed PCI can be provided by the same gNB, so only the satellite is changed. But in other cases, satellite handover without L3 mobility can be applicable to different gNBs and possibly even for regenerative deployments.

[0050] Figure 4An example of satellite switching without L3 mobility in an NTN in a transparent deployment is shown, where a first satellite 304A and a second satellite 304B provide a first NTN cell 402A and a second NTN cell 402B, respectively, the first NTN cell 402A and the second NTN cell 402B being quasi-Earth fixed cells (EFCs) serving a geographic area 410. In this regard, the first NTN cell and the second NTN cell may be the same cell, at least for a limited period of time in the geographic area served by the NTN cell. Prior to the satellite switching, the UE 208 may be stationary and served by the first NTN cell of the first satellite. As the first satellite moves away from the UE and the second satellite approaches the UE, the network (e.g., gNB 206) may indicate to the UE when the satellite switching will occur and how to perform resynchronization with the second NTN cell. The second satellite then takes over, and the UE performs downlink / uplink synchronization operations to reconnect.

[0051] exist Figure 4 , even if the UE 208 is being served by the second satellite 304B, the UE may not change the serving gNB 206, so the UE may maintain the cell configuration. The first satellite 304A and the second satellite may be configured with the same fixed PCI, the same UE context, and the same protocol stack, including synchronization signal (SS) block (SSB) generation, encoding / decoding, modulation / demodulation, the same control resource set (CORESET) configuration, handover routing, etc. However, according to the UE's reference, the first satellite and the second satellite may introduce different frequency (i.e., Doppler) and timing drifts.

[0052] Satellite handover can be divided into two additional scenarios, namely, soft satellite handover and hard satellite handover. In this regard, soft satellite handover considers a certain overlap between the first NTN cell 402A and the second NTN cell 402B, while hard satellite handover does not consider overlap between cells (although the UE 208 can consider a certain interruption time to pre-compensate the frequency and timing of the second NTN cell). For soft satellite handover, it can be assumed that the first satellite 304A and the second satellite 304B transmit their SSBs at the same time, and may have the same PCI but different time / frequency offsets, which can allow the UE to perfectly handover from the first satellite to the second satellite.

[0053] When UE 208 enters geographic area 410, the UE may perform a cell search and synchronization, during which the UE may obtain system information broadcast by gNB 206 via first satellite 304A, which provides a first NTN cell 402A serving the geographic area. Different types of system information may be sent in a system information block (SIB). For example, a block is referred to as a master information block (MIB). System information other than the MIB may be referred to as remaining minimum system information (RMSI). An example RMSI (labeled as SIB type 1 (SIB1)) includes information related to access restriction information for the UE, as well as scheduling information for other SIBs.

[0054] Other SIBs include SIB type 19 (SIB19) (SIB3 / 31 / 32 for IoT NTN), which includes information elements (IEs) with satellite assistance information for NTN access. The satellite assistance information may include, for example, configuration parameters for UEs to access the network via NTN access, such as ephemeris data, common timing advance (TA) parameters, Koffset, validity period of uplink synchronization information, and epochs. The satellite assistance information may also include, for example, a list of NTN neighbor cells, including their configuration parameters, a reference position of a serving cell provided by a satellite (e.g., a first NTN cell 402A provided by a first satellite 304A). The satellite assistance information may also include the time when the serving cell stops serving the geographic area it covers (e.g., geographic area 410), which may be provided in an IE called t-service (which indicates the period of time that the serving cell serves the geographic area).

[0055] In at least the case of a hard satellite handover (i.e., no overlap time between the old cell and the new cell), a very short interruption gap can be expected, wherein the UE 208 will switch from the first satellite 304A to the second satellite 304B in as seamless a manner as possible. In order to perform a seamless handover (where the UE detaches from the old cell and immediately starts uplink transmission in the new cell), the UE may require assistance information of the second satellite 304B (including the ephemeris data and common TA parameters of the satellite) to pre-compensate for frequency and timing drift.

[0056] One option for providing assistance information for the second satellite 304B may be to use the IE of the neighbor cells embedded in SIB19. However, this option may have disadvantages in the following case: the first and second NTN cells 402A, 402B share a fixed PCI, for example, in the case where the UE 208 stores satellite assistance information by PCI. This option may also lead to an overloaded SIB19, especially considering that the UE only needs the information of the neighbor cells close to the expiration of the t-service when the second satellite is close to the geographical area 410. One of the purposes of the unchanged PCI is to reduce the signaling overhead, and by reusing SIB19 in this way, the signaling may increase instead.

[0057] An example implementation of the present disclosure provides a mechanism for satellite switching without L3 mobility (with unchanged PCI or changed PCI), wherein the UE 208 is able to obtain assistance information of the new satellite in a timely manner without overloading the existing SIB and without increasing signaling overhead. According to an example implementation, the UE is able to obtain assistance information of the second satellite 304B in at least one information element other than the information element provided with SIB19 (e.g., in another type of separate SIB (referred to herein as SIBxx)) before the t-service of the first satellite 304A expires, without increasing signaling overhead or power consumption of the UE. In some examples, SIBxx may include one or more IEs having only system information related to satellite switching without L3 mobility, such as ephemeris data of the satellite, common TA parameters, switching gap duration, supported random access (RA) procedures, time / frequency offsets for searching for SSBs of the second NTN cell, etc.

[0058] As described in more detail below, in some examples, the gNB 206 may schedule SIBxx along with other SIBs for which SIB1 provides scheduling information. These other SIBs may be periodically transmitted, for example, via satellites 304A, 304B providing NTN cells 402A, 402B serving the geographic area 404. However, in various examples, SIBxx may or may not be transmitted along with the other SIBs. Instead, a triggering event may be defined for transmission of SIBxx or otherwise for UE 208 to obtain SIBxx. The triggering event may be defined to occur during a period in which the geographic area 404 is served by the first NTN cell 402A provided by the first satellite 304A (during the t-service of the first satellite), for example, during the last K modification periods before the expiration of the t-service.

[0059] At least until a triggering event is detected and before the t-service of the first satellite 304A expires, the UE 208 may not need to obtain SIBxx. The UE may then obtain SIBxx, apply the assistance information of the second satellite 304B to synchronize with the second satellite, and switch from the first NTN cell 402A provided by the first satellite to the second NTN cell 402B. However, in some examples, a UE in idle mode may skip obtaining SIBxx as long as the UE does not perform a random access channel (RACH) procedure before time T after the t-service of the first satellite expires. Because the UE can only obtain SIB1 once, the UE can predict the existence of SIBxx at a future point in time, but only obtain SIBxx when needed, which can significantly reduce the power consumption of the UE on SIB monitoring.

[0060] Thus, some example implementations provide a radio access node configured to schedule transmission of a SIB including an IE having assistance information for a first aerospace platform and a separate information element having assistance information for a second aerospace platform. In some examples described below, the radio access node may correspond to a gNB 206, and the first aerospace platform and the second aerospace platform may correspond to a first satellite 304A and a second satellite 304B, respectively. As described above, the first satellite and the second satellite may be configured to provide a first NTN cell 402A and a second NTN cell 402B, respectively, the first NTN cell 402A and the second NTN cell 402B being EFCs serving a geographic area 404 for a limited period of time. In some examples, the first satellite and the second satellite may share a fixed PCI.

[0061] The gNB 206 is also configured to cause the UE 208 in the first NTN cell 402A to obtain a separate IE with assistance information for the second satellite 304B before the geographic area is served by the second NTN cell 402B, during a period (t-service) in which the geographic area is served by the first NTN cell. In some more specific examples, the SIB includes: a type of SIB (e.g., SIB19) that includes an IE with assistance information for the first satellite 304A; and another type of separate SIB (e.g., SIBxx) that includes a separate IE with assistance information for the second satellite 304B. And in some of these examples, the gNB may cause the UE 208 to obtain a separate SIB including a separate IE. The UE may then apply the assistance information for the second satellite from the IE to handover the UE from the first NTN cell provided by the first satellite to the second NTN cell provided by the second satellite. In this regard, the UE may obtain the assistance information for the second satellite before the t-service of the first satellite expires, and apply the assistance information before / during any interruption gap to resynchronize to the second NTN cell.

[0062] In some more specific examples, the gNB 206 may broadcast a separate IE (e.g., in SIBxx) via the first satellite 304A for UE 208 to obtain during the period when the geographic area is served by the first NTN cell 402A, at or after the triggering event. In some examples, the triggering event may be marked by the last number of modification periods before the time when the first NTN cell stops serving the geographic area. The time when the first NTN cell stops serving the geographic area may be indicated in an IE with assistance information for the first satellite (e.g., in SIB19). Similarly, the number of modification periods may be indicated in an IE with assistance information for the first satellite. At this point, a parameter K indicating the number of modification periods may be provided to the UE as an explicit flag to command the UE to use a mechanism for satellite switching without L3 mobility. In particular, for example, if K is not empty, the UE may perform NTN cell switching without L3 mobility; otherwise, the UE may expect an RRC reconfiguration message before t-service.

[0063] In some examples, the gNB 206 can be configured to detect a triggering event and broadcast a separate IE (e.g., in SIBxx) only upon or after the triggering event is detected. In other examples, the gNB can broadcast the separate IE before and after the triggering event is detected, and the UE 208 need not obtain the separate IE at least until the triggering event is detected at the UE. In some of these other examples, the triggering event can be detected by the UE. In these and similar examples where the triggering event is marked by the last number of modification periods, the gNB can send a paging message to the UE so that the UE obtains the separate IE during one of the last number of modification periods (e.g., during a modification information procedure).

[0064] The example implementations of the present disclosure described above from the perspective of the gNB 206 (radio access node) are equally applicable to the UE 208. In this regard, information or messages sent to or received from the UE (from the perspective of the gNB) may instead be received from or sent to the gNB (from the perspective of the UE).

[0065] Thus, an example implementation of the present disclosure also provides a UE 208 configured to receive scheduling information for a SIB (from a gNB 206 via a first satellite 304A), the SIB including an IE with assistance information for the first satellite (e.g., in SIB19) and a separate IE with assistance information for the second satellite 304B (e.g., in SIBxx). The UE in the first NTN cell 402A may obtain a separate IE with assistance information for the second satellite before the geographic area 404 is served by the second NTN cell, during a period when the geographic area is served by the first NTN cell. The UE may then apply the assistance information for the second satellite to handover the UE from the first NTN cell provided by the first satellite to the second NTN cell 402B provided by the second satellite.

[0066] As described above, the gNB 206 of the network may include assistance information for the second satellite 304B in an IE (e.g., in SIBxx) that is separate from the IE (e.g., in SIB19) with assistance information for the first satellite 304A. In this regard, the IE with assistance information for the second satellite may be transparent to the IE with assistance information for the first satellite, and may also reduce the load in the SIB19 that may include these IEs. Scheduling information for a separate IE may be provided, but not actually used (saving resources on the physical layer) until strictly needed (close to satellite switching). This can allow the UE to significantly minimize the acquisition of resources for the second satellite.

[0067] Figure 5A timing diagram 500 is shown according to some example implementations. As shown, the first two scheduled transmissions 502 of SIBxx are not performed because these scheduled transmissions are before the triggering event, which is before the satellite switching time 504. However, on the third scheduled transmission 506, at or after the triggering event (before the satellite switching time), the network sends SIBxx with assistance information for the second satellite 304B. SIBs 508 sent via the second satellite after the satellite switching are also shown, and these SIBs may include SIB19 with assistance information for the second satellite. SIBs sent via the first satellite before the transmission of the scheduled transmissions / SIBxx are not shown. However, these SIBs may include a validity time that extends to the satellite switching so that the UE can still connect to the first satellite (the current serving satellite before the satellite switching).

[0068] Figure 6 6 is a flow chart illustrating various steps in a method 600 implemented according to some examples. The method may include a network (e.g., gNB 206) scheduling a SIB, as indicated by block 502. The network may monitor the remaining time of the t-service for the first satellite 304A and not send a SIBxx with assistance information for the second satellite 304B until the last K modification periods before the t-service, as indicated by blocks 504 and 506. When the network detects that the number of modification periods remaining is equal to or less than K, the network may broadcast or otherwise send the SIBxx for the UE to obtain, as indicated by block 508. The UE may then apply the assistance information for the second satellite, which may include reading and using parameters of the second satellite (e.g., ephemeris data, TA parameters, and / or Koffset), as indicated by block 510. When the UE pre-compensates for frequency and time drift and knows how to communicate with the second satellite, the UE may resynchronize the downlink and uplink flows so the connection with the gNB 206 continues. The UE does not need to repeatedly reacquire all SIBs, and the network does not need to page all UEs using the modification information procedure, which can save signaling load and UE power consumption.

[0069] Figures 7A-7E is a more descriptive flow chart illustrating various steps in a method 700 from the perspective of a radio access node (e.g., gNB 206) according to various example implementations. The method includes scheduling transmission of a system information block (SIB) including an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, such as Fig. 7AThe method further includes causing a user equipment in the first NTN cell to obtain a separate at least one information element having assistance information for the second aerospace platform before the geographic area is served by the second NTN cell and during the period when the geographic area is served by the first NTN cell, as shown in block 704.

[0070] In some examples, the SIB includes: a type of SIB including an information element having assistance information for a first aerospace platform; and another type of separate SIB including a separate at least one information element having assistance information for a second aerospace platform. In some of these examples, causing the user equipment to obtain the separate at least one information element at block 704 includes causing the user equipment to obtain the separate SIB including the separate at least one information element, such as Figure 7B As shown in box 706.

[0071] In some examples, causing the user equipment to obtain the single at least one information element at block 704 includes: broadcasting the single at least one information element for the user equipment to obtain during a period of time when the geographic area is served by the first NTN cell, upon or after the triggering event, such as Figure 7C In some of these examples, method 700 further includes: detecting a triggering event, such as Fig.7D Then, at block 708, the separate at least one information element is broadcast only when or after the triggering event is detected. In other of these examples, at block 708, the separate at least one information element is broadcast before and after the triggering event is detected, and the user equipment does not need to obtain the separate at least one information element at least until the triggering event is detected at the user equipment.

[0072] In some examples, the method 700 further includes: sending a paging message to the user equipment so that the user equipment obtains at least one separate information element in block 704, such as Fig. 7E As shown in box 712.

[0073] Figures 8A-8E 8 is a more descriptive flow chart showing various steps in method 800 from the perspective of UE 208 according to various example implementations. The method includes: receiving scheduling information for a system information block (SIB) at a user equipment, such as Fig. 8AAs shown in block 802 of . The SIB includes an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area for a limited period of time. The method also includes obtaining, at a user equipment in the first NTN cell, the separate at least one information element having assistance information for the second aerospace platform, before the geographic area is served by the second NTN cell, during the period when the geographic area is served by the first NTN cell, as shown in block 804.

[0074] In some examples, the method 800 further includes: applying the assistance information for the second aerospace platform to switch the user equipment from the first NTN cell provided by the first aerospace platform to the second NTN cell provided by the second aerospace platform, such as Figure 8B As shown in box 806.

[0075] In some examples, the SIB includes: a type of SIB including an information element having auxiliary information for a first aerospace platform; and another type of separate SIB including a separate at least one information element having auxiliary information for a second aerospace platform. In some of these examples, obtaining the separate at least one information element at block 804 includes obtaining a separate SIB including the separate at least one information element, such as Figure 8C As shown in box 808.

[0076] In some examples, the at least one separate information element is broadcast before and after the triggering event is detected. The method 800 also includes: detecting the triggering event at the user equipment, the user equipment need not obtain the at least one separate information element at least until the triggering event is detected at the user equipment, such as Fig.8D As shown in box 810.

[0077] In some examples, the method 800 further includes: receiving a paging message at the user equipment so that the user equipment obtains at block 804 at least one separate information element, such as Fig. 8E As shown in box 812.

[0078] According to example implementations of the present disclosure, the telecommunications system 100 or PLMN 102 and its components, such as UE 208, radio access nodes (e.g., gNB 206), aerospace platforms (e.g., satellites 304, 304A, 304B), and / or NTN gateway 308, may be implemented by various means. The means for implementing the system and its components may include hardware, which is implemented alone or under the guidance of one or more computer programs from a computer-readable storage medium (e.g., computer memory (or simply "memory")). In some examples, one or more devices may be configured to function as or otherwise implement the system and its components shown and described herein. In examples involving more than one device, the corresponding devices may be connected to each other or otherwise communicate with each other in a variety of different ways, such as directly or indirectly via a wired or wireless network, etc.

[0079] Fig. 9 An apparatus 900 according to some example implementations of the present disclosure is shown. In general, an apparatus of an exemplary implementation of the present disclosure may include, contain, or be embodied in one or more fixed or portable electronic devices. Examples of suitable electronic devices include wearable computers, mobile phones, portable computers, desktop computers, workstation computers, servers (server computers), etc. The apparatus may include one or more of each of a plurality of components, such as a processing circuit 902 connected to a computer-readable storage medium 904.

[0080] Processing circuitry 902 may include one or more processors alone, or in combination with one or more computer-readable storage media. Processing circuitry is typically any computer hardware capable of processing information (e.g., data, computer programs, and / or other suitable electronic information). Processing circuitry includes a collection of electronic circuits, some of which may be packaged as an integrated circuit or multiple interconnected integrated circuits (integrated circuits are sometimes more commonly referred to as "chips"). Processing circuitry may be configured to execute computer programs, which may be stored on the processing circuitry or otherwise stored in a computer-readable storage medium 904 (of the same or another device).

[0081] The processing circuit 902 may be a plurality of processors, a multi-core processor, or some other type of processor, depending on the particular implementation. In addition, the processing circuit may be implemented using a plurality of heterogeneous processor systems in which a main processor and one or more secondary processors are present on a single chip. As another illustrative example, the processing circuit may be a symmetric multiprocessor system comprising a plurality of processors of the same type. In yet another example, the processing circuit may be embodied as or otherwise include one or more ASICs, FPGAs, and the like. Thus, although the processing circuit is capable of executing a computer program to perform one or more functions, the processing circuits of various examples are capable of performing one or more functions without the aid of a computer program. In either case, the processing circuit may be appropriately programmed to perform functions or operations implemented according to the examples of the present disclosure.

[0082] Computer-readable storage media 904 is generally any computer hardware capable of temporarily and / or permanently storing information (e.g., data, computer programs (e.g., computer-readable program code 906), and / or other suitable information). Computer-readable storage media may include volatile and / or non-volatile memory and may be fixed or removable. Examples of suitable memory include random access memory (RAM), read-only memory (ROM), hard drive, flash memory, thumb drive, removable computer disk, optical disk, or some combination of the above. Computer-readable storage media are non-transitory devices capable of storing information and can be distinguished from computer-readable transmission media (such as electronic transient signals) that can carry information from one location to another. As used herein, the term "non-transitory" is a limitation on the medium itself (i.e., tangible, rather than a signal), rather than a limitation on the persistence of data storage (e.g., RAM vs. ROM). Computer-readable media as described herein may generally refer to computer-readable storage media or computer-readable transmission media.

[0083] In addition to the computer-readable storage medium 904, the processing circuit 902 can also be connected to one or more interfaces for displaying, sending and / or receiving information. These interfaces may include a communication interface 908 and / or one or more user interfaces. The communication interface can be configured to send information to other devices, networks, etc. and / or receive information therefrom. The communication interface can be configured to send and / or receive information via a physical (wired) and / or wireless communication link. The example of a suitable communication interface includes a network interface controller (NIC), a wireless NIC (WNIC), etc.

[0084] The user interface may include a display 910 and / or one or more user input interfaces 912. The display may be configured to present or otherwise display information to a user, and suitable examples of displays include liquid crystal displays (LCDs), light emitting diode (LED) displays, organic LED (OLED) displays, active matrix OLED (AMOLED), etc. The user input interface may be wired or wireless, and may be configured to receive information from a user into the device, such as for processing, storage, and / or display. Suitable examples of user input interfaces include microphones, image or video capture devices, keyboards or keypads, joysticks, touch-sensitive surfaces (separate from or integrated into a touch screen), biosensors, etc. The user interface may also include one or more interfaces for communicating with peripheral devices (e.g., printers, scanners, etc.).

[0085] As described above, program code instructions can be stored in a computer-readable storage medium and executed by a processing circuit, which is thereby programmed to implement the functions of the systems, subsystems, tools, and corresponding units described herein. As will be appreciated, any suitable program code instructions can be loaded from a computer-readable storage medium onto a computer or other programmable device to produce a specific machine, so that the specific machine becomes a device for implementing the functions specified herein. These program code instructions can also be stored in a computer-readable storage medium, which can guide a computer, a processing circuit, or other programmable device to run in a particular manner, thereby generating a specific machine or a specific product. Instructions stored in a computer-readable storage medium can produce products, wherein the products become devices for implementing the functions described herein. Program code instructions can be obtained from a computer-readable storage medium, and loaded into a computer, a processing circuit, or other programmable device, so that a computer, a processing circuit, or other programmable device is configured to perform operations to be performed on a computer, a processing circuit, or other programmable device, or performed by a computer, a processing circuit, or other programmable device.

[0086] The retrieval, loading, and execution of program code instructions may be performed sequentially such that one instruction is retrieved, loaded, and executed at a time. In some example implementations, the retrieval, loading, and / or execution may be performed in parallel such that multiple instructions are retrieved, loaded, and / or executed together. The execution of program code instructions may produce a computer-implemented process such that the instructions executed by a computer, processing circuit, or other programmable device provide operations for implementing the functions described herein.

[0087] The processing circuit executes the instructions or stores the instructions in the computer-readable storage medium to support a combination of operations for performing the specified functions. In this way, the device 900 may include a processing circuit 902 and a computer-readable storage medium 904 coupled to the processing circuit, wherein the processing circuit is configured to execute a computer-readable program code 906 stored in the computer-readable storage medium. It will also be understood that one or more functions and combinations of functions may be implemented by a dedicated hardware-based computer system and / or processing circuit that performs the specified functions, or by a combination of dedicated hardware and program code instructions.

[0088] As explained above and reiterated below, the present disclosure includes, but is not limited to, the following example implementations.

[0089] Clause 1. An apparatus comprising: at least one memory configured to store a computer-readable program code; and at least one processing circuit configured to access the at least one memory and execute the computer-readable program code so that the apparatus at least: schedules transmission of a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area within a limited period of time; and enables a user equipment in the first NTN cell to obtain, before the geographic area is served by the second NTN cell, the separate at least one information element having assistance information for the second aerospace platform during the period of time when the geographic area is served by the first NTN cell.

[0090] Clause 2. An apparatus according to clause 1, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein causing a user device to obtain the separate at least one information element comprises causing the user device to obtain a separate SIB comprising at least one separate information element.

[0091] Clause 3. An apparatus according to clause 1 or clause 2, wherein enabling the user equipment to obtain at least one separate information element comprises: broadcasting at least one separate information element for the user equipment to obtain during a period when the geographical area is served by the first NTN cell, at or after a triggering event.

[0092] Clause 4. The apparatus of clause 3, wherein the at least one processing circuit is configured to execute the computer readable program code such that the apparatus further detects a triggering event, and the individual at least one information element is broadcast only upon or after the triggering event is detected.

[0093] Clause 5. An apparatus according to clause 3 or clause 4, wherein the separate at least one information element is broadcast before and after the triggering event is detected, and the user equipment does not need to obtain the separate at least one information element at least until the triggering event is detected at the user equipment.

[0094] Clause 6. An apparatus as described in any of clauses 1 to 5, wherein the triggering event is marked by the last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

[0095] Clause 7. The apparatus of clause 6, wherein the time at which the first NTN cell stops serving the geographic area is indicated in an information element with assistance information for the first aerospace platform.

[0096] Clause 8. Apparatus according to clause 6 or clause 7, wherein the last number of modification periods is indicated in an information element with the auxiliary information for the first aerospace platform.

[0097] Clause 9. An apparatus according to any of clauses 1 to 8, wherein at least one processing circuit is configured to execute computer-readable program code to cause the apparatus to further send a paging message to the user equipment to cause the user equipment to obtain the separate at least one information element.

[0098] Clause 10. An apparatus comprising: a component for scheduling transmission of a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-geo-fixed cells serving a geographic area within a limited period of time; and a component for enabling a user equipment in the first NTN cell to obtain the separate at least one information element having assistance information for the second aerospace platform before the geographic area is served by the second NTN cell and during the period when the geographic area is served by the first NTN cell.

[0099] Clause 11. An apparatus according to clause 10, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein enabling a user device to obtain the separate at least one information element comprises a component for enabling the user device to obtain the separate SIB comprising the separate at least one information element.

[0100] Clause 12. An apparatus according to clause 10 or clause 11, wherein enabling the user equipment to obtain the separate at least one information element includes a component for broadcasting the separate at least one information element for the user equipment to obtain during a period when the geographical area is served by the first NTN cell, at or after a triggering event.

[0101] Clause 13. The apparatus of clause 12, wherein the apparatus further comprises means for detecting a triggering event, and the individual at least one information element is broadcast only upon or after the triggering event is detected.

[0102] Clause 14. An apparatus according to clause 12 or clause 13, wherein the separate at least one information element is broadcast before and after the triggering event is detected, and the user equipment does not need to obtain the separate at least one information element at least until the triggering event is detected at the user equipment.

[0103] Clause 15. An apparatus as described in any of clauses 10 to 14, wherein the triggering event is marked by a last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

[0104] Clause 16. The apparatus of clause 15, wherein the time at which the first NTN cell stops serving the geographic area is indicated in the information element with the assistance information for the first aerospace platform.

[0105] Clause 17. The apparatus of clause 15 or clause 16, wherein the last number of modification periods is indicated in an information element with the auxiliary information for the first aerospace platform.

[0106] Clause 18. An apparatus as described in any of clauses 10 to 17, wherein the apparatus further comprises means for sending a paging message to a user equipment so that the user equipment obtains the separate at least one information element.

[0107] Clause 19. An apparatus comprising: at least one memory configured to store a computer-readable program code; and at least one processing circuit configured to access the at least one memory and execute the computer-readable program code so that the apparatus at least: receives scheduling information for a system information block (SIB) at a user equipment, the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area within a limited period of time; and obtains, at a user equipment in the first NTN cell, during a period of time when the geographic area is served by the first NTN cell before the geographic area is served by the second NTN cell, the separate at least one information element having assistance information for the second aerospace platform.

[0108] Clause 20. An apparatus according to clause 19, wherein at least one processing circuit is configured to execute computer readable program code so that the apparatus also applies the assistance information for the second aerospace platform to switch the user equipment from the first NTN cell provided by the first aerospace platform to the second NTN cell provided by the second aerospace platform.

[0109] Clause 21. An apparatus according to clause 19 or clause 20, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein obtaining the separate at least one information element comprises: causing the apparatus to obtain the separate SIB comprising the separate at least one information element.

[0110] Clause 22. An apparatus as described in any of clauses 19 to 21, wherein at least one information element is broadcast for acquisition by user equipment upon or after a triggering event during a period in which the geographical area is served by the first NTN cell.

[0111] Clause 23. The apparatus of clause 22, wherein the individual at least one information element is broadcast only upon or after a triggering event is detected.

[0112] Clause 24. An apparatus according to clause 22 or clause 23, wherein the separate at least one information element is broadcast before and after a triggering event is detected, and at least one processing circuit is configured to execute a computer-readable program code so that the apparatus also detects a triggering event at a user device, and the user device does not need to obtain the separate at least one information element at least until the triggering event is detected at the user device.

[0113] Clause 25. An apparatus as described in any of clauses 19 to 24, wherein the triggering event is marked by the last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

[0114] Clause 26. The apparatus of clause 25, wherein the time at which the first NTN cell stops serving the geographic area is indicated in an information element with assistance information for the first aerospace platform.

[0115] Clause 27. The apparatus of clause 25 or clause 26, wherein the last number of modification periods is indicated in an information element with the auxiliary information for the first aerospace platform.

[0116] Clause 28. An apparatus as described in any of clauses 19 to 27, wherein at least one processing circuit is configured to execute computer-readable program code to cause the apparatus to also receive a paging message at the user equipment to cause the user equipment to obtain the separate at least one information element.

[0117] Clause 29. An apparatus comprising: means for receiving, at a user equipment, scheduling information for a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area for a limited period of time; and means for obtaining, at a user equipment in the first NTN cell, the separate at least one information element having assistance information for the second aerospace platform, before the geographic area is served by the second NTN cell, during a period of time when the geographic area is served by the first NTN cell.

[0118] Clause 30. The apparatus of clause 29, wherein the apparatus further comprises means for applying the assistance information for the second aerospace platform to handover the user equipment from the first NTN cell provided by the first aerospace platform to the second NTN cell provided by the second aerospace platform.

[0119] Clause 31. An apparatus according to clause 29 or clause 30, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein obtaining the separate at least one information element comprises a component for obtaining the separate SIB comprising the separate at least one information element.

[0120] Clause 32. An apparatus as described in any of clauses 29 to 31, wherein at least one information element is broadcast for acquisition by the user equipment upon or after a triggering event during a period in which the geographical area is served by the first NTN cell.

[0121] Clause 33. The apparatus of clause 32, wherein the individual at least one information element is broadcast only upon or after a triggering event is detected.

[0122] Clause 34. An apparatus according to clause 32 or clause 33, wherein at least one separate information element is broadcast before and after a triggering event is detected, and the apparatus further comprises a component for detecting a triggering event at a user device, the user device not needing to obtain the at least one separate information element at least until the triggering event is detected at the user device.

[0123] Clause 35. An apparatus as described in any of clauses 29 to 34, wherein the triggering event is marked by the last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

[0124] Clause 36. The apparatus of clause 35, wherein the time at which the first NTN cell stops serving the geographic area is indicated in the information element with the assistance information for the first aerospace platform.

[0125] Clause 37. The apparatus of clause 35 or clause 36, wherein the last number of modification periods is indicated in an information element with the auxiliary information for the first aerospace platform.

[0126] Clause 38. An apparatus as described in any of clauses 29 to 37, wherein the apparatus further comprises second means for receiving a paging message at a user equipment so that the user equipment obtains the separate at least one information element.

[0127] Clause 39. A method comprising: scheduling transmission of a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area within a limited period of time; and enabling a user equipment in the first NTN cell to obtain the separate at least one information element having assistance information for the second aerospace platform before the geographic area is served by the second NTN cell and during the period when the geographic area is served by the first NTN cell.

[0128] Clause 40. A method according to clause 39, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein causing a user device to obtain the separate at least one information element comprises causing the user device to obtain a separate SIB comprising the separate at least one information element.

[0129] Clause 41. A method according to clause 39 or clause 40, wherein enabling the user equipment to obtain at least one separate information element comprises: broadcasting at least one separate information element for the user equipment to obtain during a period when the geographical area is served by the first NTN cell, at or after a triggering event.

[0130] Clause 42. The method of clause 41, wherein the method further comprises: detecting a triggering event, and the individual at least one information element is broadcast only when or after the triggering event is detected.

[0131] Clause 43. A method according to clause 41 or clause 42, wherein the separate at least one information element is broadcast before and after the triggering event is detected, and the user equipment does not need to obtain the separate at least one information element at least until the triggering event is detected at the user equipment.

[0132] Clause 44. A method as described in any of clauses 39 to 43, wherein the triggering event is marked by the last number of modification periods before the time at which the first NTN cell ceased serving the geographical area.

[0133] Clause 45. The method of clause 44, wherein the time at which the first NTN cell stops serving the geographic area is indicated in an information element with assistance information for the first aerospace platform.

[0134] Clause 46. The method of clause 44 or clause 45, wherein the last number of modification periods is indicated in an information element with the auxiliary information for the first aerospace platform.

[0135] Clause 47. A method according to any one of clauses 39 to 46, wherein the method further comprises: sending a paging message to a user equipment so that the user equipment obtains the separate at least one information element.

[0136] Clause 48. A method comprising: receiving, at a user equipment, scheduling information for a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area for a limited period of time; and obtaining, at a user equipment in the first NTN cell, the separate at least one information element having assistance information for the second aerospace platform, before the geographic area is served by the second NTN cell, during the period when the geographic area is served by the first NTN cell.

[0137] Clause 49. The method of clause 48, wherein the method further comprises: applying the assistance information for the second aerospace platform to handover the user equipment from the first NTN cell provided by the first aerospace platform to the second NTN cell provided by the second aerospace platform.

[0138] Clause 50. A method according to clause 48 or clause 49, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein obtaining the separate at least one information element comprises: obtaining a separate SIB comprising the separate at least one information element.

[0139] Clause 51. A method as described in any of clauses 48 to 50, wherein at least one information element is broadcast for acquisition by the user equipment upon or after a triggering event during a period in which the geographical area is served by the first NTN cell.

[0140] Clause 52. The method of clause 51, wherein the individual at least one information element is broadcast only upon or after a triggering event is detected.

[0141] Clause 53. A method according to clause 51 or clause 52, wherein at least one separate information element is broadcast before and after a triggering event is detected, and the method further comprises: detecting a triggering event at a user device, the user device not needing to obtain at least one separate information element at least until the triggering event is detected at the user device.

[0142] Clause 54. A method as described in any of clauses 48 to 53, wherein the triggering event is marked by the last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

[0143] Clause 55. The method of clause 54, wherein the time at which the first NTN cell stops serving the geographic area is indicated in an information element with assistance information for the first aerospace platform.

[0144] Clause 56. The method of clause 54 or clause 55, wherein the last number of modification periods is indicated in an information element with the auxiliary information for the first aerospace platform.

[0145] Clause 57. A method as described in any of clauses 48 to 56, wherein the method further comprises: receiving a paging message at the user equipment so that the user equipment obtains the individual at least one information element.

[0146] Clause 58. A computer-readable storage medium that is non-transitory and has computer-readable program code stored therein, the computer-readable program code in response to being executed by at least one processing circuit causing the apparatus to at least: schedule transmission of a system information block (SIB), the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographic area within a limited period of time; and causing a user equipment in the first NTN cell to obtain, before the geographic area is served by the second NTN cell, the separate at least one information element having assistance information for the second aerospace platform during the period of time when the geographic area is served by the first NTN cell.

[0147] Clause 59. A computer-readable storage medium according to clause 58, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein causing a user device to obtain the separate at least one information element comprises causing the user device to obtain a separate SIB comprising the separate at least one information element.

[0148] Clause 60. A computer-readable storage medium according to clause 58 or clause 59, wherein causing the user equipment to obtain the separate at least one information element comprises: broadcasting the separate at least one information element for the user equipment to obtain during a period when the geographic area is served by the first NTN cell, at or after a triggering event.

[0149] Clause 61. A computer-readable storage medium according to clause 60, wherein the computer-readable storage medium also stores therein a computer-readable program code, the computer-readable program code being executed by at least one processing circuit in response to the device also detecting a trigger event, and at least one individual information element is broadcast only when or after the trigger event is detected.

[0150] Clause 62. A computer-readable storage medium according to clause 60 or clause 61, wherein the at least one separate information element is broadcast before and after the triggering event is detected, and the user device does not need to obtain the at least one separate information element at least until the triggering event is detected at the user device.

[0151] Clause 63. The computer-readable storage medium of any of clauses 58 to 62, wherein the triggering event is marked by a last number of modification periods before a time when the first NTN cell ceased serving the geographic area.

[0152] Clause 64. The computer-readable storage medium of clause 63, wherein the time at which the first NTN cell stops serving the geographic area is indicated in an information element with assistance information for the first aerospace platform.

[0153] Clause 65. The computer-readable storage medium of clause 63 or clause 64, wherein the last number of modification periods is indicated in an information element having the auxiliary information for the first aerospace platform.

[0154] Clause 66. A computer-readable storage medium according to any one of clauses 58 to 65, wherein the computer-readable storage medium also stores therein a computer-readable program code, and the computer-readable program code, in response to being executed by at least one processing circuit, causes the apparatus to also send a paging message to a user equipment so that the user equipment obtains at least one separate information element.

[0155] Clause 67. A computer-readable storage medium that is non-transitory and has computer-readable program code stored therein, the computer-readable program code being responsive to being executed by at least one processing circuit, causing the apparatus to at least: receive scheduling information for a system information block (SIB) at a user equipment, the SIB comprising an information element having assistance information for a first aerospace platform and a separate at least one information element having assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells that serve a geographic area within a limited period of time; and obtain, at a user equipment in the first NTN cell, during a period of time when the geographic area is served by the first NTN cell, before the geographic area is served by the second NTN cell, at least one separate information element having assistance information for the second aerospace platform.

[0156] Clause 68. A computer-readable storage medium according to clause 67, wherein the computer-readable storage medium also has computer-readable program code stored therein, the computer-readable program code being responsive to being executed by at least one processing circuit so that the apparatus also applies the assistance information for the second aerospace platform to switch the user equipment from the first NTN cell provided by the first aerospace platform to the second NTN cell provided by the second aerospace platform.

[0157] Clause 69. A computer-readable storage medium according to clause 67 or clause 68, wherein the SIB comprises: a type of SIB comprising an information element having auxiliary information for a first aerospace platform; and another type of separate SIB comprising at least one separate information element having auxiliary information for a second aerospace platform, and wherein obtaining the separate at least one information element comprises: causing the device to obtain the separate SIB comprising the separate at least one information element.

[0158] Clause 70. The computer-readable storage medium of any of clauses 67 to 69, wherein at least one information element is broadcast for acquisition by user equipment upon or after a triggering event during a period in which the geographic area is served by the first NTN cell.

[0159] Clause 71. The computer-readable storage medium of clause 70, wherein the individual at least one information element is broadcast only upon or after a triggering event is detected.

[0160] Clause 72. A computer-readable storage medium according to clause 70 or clause 71, wherein the separate at least one information element is broadcast before and after a triggering event is detected, and the computer-readable storage medium also stores therein a computer-readable program code, the computer-readable program code being executed by at least one processing circuit in response to the apparatus also detecting a triggering event at a user device, and the user device does not need to obtain the separate at least one information element at least until the triggering event is detected at the user device.

[0161] Clause 73. The computer-readable storage medium of any of clauses 67 to 72, wherein the triggering event is marked by a last number of modification periods before a time when the first NTN cell ceased serving the geographic area.

[0162] Clause 74. The computer-readable storage medium of clause 73, wherein the time at which the first NTN cell stops serving the geographic area is indicated in the information element with the assistance information for the first aerospace platform.

[0163] Clause 75. The computer-readable storage medium of clause 73 or clause 74, wherein the last number of modification periods is indicated in an information element having the auxiliary information for the first aerospace platform.

[0164] Clause 76. A computer-readable storage medium according to any one of clauses 67 to 75, wherein the computer-readable storage medium also stores therein a computer-readable program code, and the computer-readable program code, in response to being executed by at least one processing circuit, causes the device to also receive a paging message at a user equipment so that the user equipment obtains at least one separate information element.

[0165] Clause 77. An apparatus comprising means for performing the method of any of clauses 39 to 47.

[0166] Clause 78. A computer readable medium comprising computer readable program code, the computer readable program code in response to being executed by at least one processing circuit, causing an apparatus to perform the method of any of clauses 39 to 47.

[0167] Clause 79. A computer readable storage medium comprising computer readable program code, the computer readable program code in response to being executed by at least one processing circuit, causing an apparatus to perform the method of any of clauses 39 to 47.

[0168] Clause 80. A computer program comprising computer readable program code which, in response to being executed by at least one processing circuit, causes an apparatus to perform the method of any of clauses 39 to 47.

[0169] Clause 81. An apparatus comprising means for performing the method of any one of clauses 48 to 57.

[0170] Clause 82. A computer readable medium comprising computer readable program code, the computer readable program code in response to being executed by at least one processing circuit, causing an apparatus to perform the method of any of clauses 48 to 57.

[0171] Clause 83. A computer readable storage medium comprising computer readable program code, the computer readable program code in response to being executed by at least one processing circuit, causing an apparatus to perform the method of any of clauses 48 to 57.

[0172] Clause 84. A computer program comprising computer readable program code which, in response to being executed by at least one processing circuit, causes an apparatus to perform the method of any of clauses 48 to 57.

[0173] Benefiting from the teachings provided in the above description and the associated drawings, those skilled in the art to which the present disclosure belongs will think of many modifications and other implementations of the present disclosure set forth herein. Therefore, it will be understood that the present disclosure is not limited to the specific implementation disclosed, and modifications and other implementations are intended to be included within the scope of the appended claims. In addition, although the above description and the associated drawings describe example implementations in the context of specific example combinations of units and / or functions, it should be understood that alternative implementations can provide different unit and / or function combinations without departing from the scope of the appended claims. In this regard, for example, unit and / or function combinations different from those combinations explicitly described above can also be conceived, as can be set forth in some of the appended claims. Although specific terms are used herein, they are only used in a general and descriptive sense and not for limiting purposes.

Claims

1. A device comprising: at least one memory configured to store computer readable program code; as well as at least one processing circuit configured to access the at least one memory and execute the computer readable program code to cause the apparatus to at least: Scheduling transmission of a system information block (SIB), the SIB comprising an information element with assistance information for a first aerospace platform and a separate at least one information element with assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographical area for a limited period of time; as well as The user equipment in the first NTN cell is caused to obtain the separate at least one information element having the auxiliary information for the second aerospace platform during a period when the geographical area is served by the first NTN cell before the geographical area is served by the second NTN cell.

2. The device according to claim 1, wherein: The SIB comprises: a type of SIB comprising the information element having the auxiliary information for the first aerospace platform; and another type of separate SIB comprising the separate at least one information element having the auxiliary information for the second aerospace platform, and The enabling the user equipment to obtain the at least one separate information element includes: enabling the user equipment to obtain the separate SIB including the at least one separate information element.

3. The device according to claim 1, wherein: Enabling the user equipment to obtain the single at least one information element comprises: broadcasting the single at least one information element for the user equipment to obtain upon or after a triggering event during a period in which the geographical area is served by the first NTN cell.

4. The device according to claim 3, wherein: The at least one processing circuit is configured to execute the computer readable program code such that the apparatus further detects the triggering event, and the separate at least one information element is broadcast only upon or after the triggering event is detected.

5. The device according to claim 3, wherein: The separate at least one information element is broadcasted before and after the triggering event is detected, and the user equipment does not need to obtain the separate at least one information element at least until the triggering event is detected at the user equipment.

6. The device according to claim 1, wherein: The triggering event is marked by a last number of modification periods before the time at which the first NTN cell ceased serving the geographical area.

7. A device comprising: at least one memory configured to store computer readable program code; as well as at least one processing circuit configured to access the at least one memory and execute the computer readable program code to cause the apparatus to at least: receiving, at a user equipment, scheduling information for a system information block (SIB), the SIB comprising an information element with assistance information for a first aerospace platform and a separate at least one information element with assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographical area for a limited period of time; as well as The separate at least one information element with the assistance information for the second aerospace platform is obtained at the user equipment in the first NTN cell during a period when the geographical area is served by the first NTN cell before the geographical area is served by the second NTN cell.

8. The device according to claim 7, wherein: The SIB comprises: a type of SIB comprising the information element having the auxiliary information for the first aerospace platform; and another type of separate SIB comprising the separate at least one information element having the auxiliary information for the second aerospace platform, and The obtaining of the at least one separate information element comprises: enabling the device to obtain the separate SIB including the at least one separate information element.

9. The device according to claim 7, wherein: During a period in which the geographical area is served by the first NTN cell, upon or after a triggering event, the at least one information element is broadcast for acquisition by the user equipment.

10. The device according to claim 9, wherein: The separate at least one information element is broadcast only upon or after the triggering event is detected.

11. The device according to claim 9, wherein: The separate at least one information element is broadcast before and after the triggering event is detected, and the at least one processing circuit is configured to execute the computer-readable program code so that the apparatus also detects the triggering event at the user equipment, and the user equipment does not need to obtain the separate at least one information element at least until the triggering event is detected at the user equipment.

12. The device according to claim 7, wherein: The triggering event is marked by the last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

13. A method comprising: Scheduling transmission of a system information block (SIB), the SIB comprising an information element with assistance information for a first aerospace platform and a separate at least one information element with assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographical area for a limited period of time; as well as The user equipment in the first NTN cell is caused to obtain the separate at least one information element having the auxiliary information for the second aerospace platform during a period when the geographical area is served by the first NTN cell before the geographical area is served by the second NTN cell.

14. The method according to claim 13, wherein: The SIB comprises: a type of SIB comprising the information element having the auxiliary information for the first aerospace platform; and another type of separate SIB comprising the separate at least one information element having the auxiliary information for the second aerospace platform, and The enabling the user equipment to obtain the at least one separate information element includes: enabling the user equipment to obtain the separate SIB including the at least one separate information element.

15. The method according to claim 13, wherein: Enabling the user equipment to obtain the single at least one information element comprises: broadcasting the single at least one information element for the user equipment to obtain upon or after a triggering event during a period in which the geographical area is served by the first NTN cell.

16. The method according to claim 13, wherein: The triggering event is marked by the last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

17. A method comprising: receiving, at a user equipment, scheduling information for a system information block (SIB), the SIB comprising an information element with assistance information for a first aerospace platform and a separate at least one information element with assistance information for a second aerospace platform, the first aerospace platform and the second aerospace platform being configured to provide a first non-terrestrial network (NTN) cell and a second NTN cell, respectively, the first NTN cell and the second NTN cell being quasi-terrestrial fixed cells serving a geographical area for a limited period of time; as well as The separate at least one information element with the assistance information for the second aerospace platform is obtained at the user equipment in the first NTN cell during a period when the geographical area is served by the first NTN cell before the geographical area is served by the second NTN cell.

18. The method according to claim 17, wherein: The SIB comprises: a type of SIB comprising the information element having the auxiliary information for the first aerospace platform; and another type of separate SIB comprising the separate at least one information element having the auxiliary information for the second aerospace platform, and The obtaining of the at least one separate information element comprises: obtaining the separate SIB comprising the at least one separate information element.

19. The method according to claim 17, wherein: During a period in which the geographical area is served by the first NTN cell, upon or after a triggering event, the at least one information element is broadcast for acquisition by the user equipment.

20. The method according to claim 17, wherein: The triggering event is marked by the last number of modification periods before the time when the first NTN cell stopped serving the geographical area.

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