Method and apparatus in a wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). Disclosed is a method of operating a User Equipment, operably connected to a terrestrial telecommunication network, for mobility to an Air to Ground, ATG, telecommunication network, comprising the steps of: receiving ATG assistance information for performing measurements of an ATG cell in the ATG telecommunication network; performing measurement of the ATG cell; and performing mobility to the ATG cell.

Description

METHOD AND APPARATUS IN A WIRELESS COMMUNICATION SYSTEM

[0001] The present disclosure relates to a communication system, and more particularly, and more particularly, to a method and device for efficiently performing a wireless network function. Furthermore, the present disclosure relates to improvement in managing mobility between a terrestrial telecommunication network and an Air to Ground, ATG, network.

[0002] Considering the development of wireless communication from generation to generation, the technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th-generation) communication systems, it is expected that the number of connected devices will exponentially grow. Increasingly, these will be connected to communication networks.

[0003] Examples of connected things may include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machines, and factory equipment. Mobile devices are expected to evolve in various form-factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th-generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond-5G systems.

[0004] 6G communication systems, which are expected to be commercialized around 2030, will have a peak data rate of tera (1,000 giga)-level bps and a radio latency less than 100μsec, and thus will be 50 times as fast as 5G communication systems and have the 1 / 10 radio latency thereof.

[0005] In order to accomplish such a high data rate and an ultra-low latency, it has been considered to implement 6G communication systems in a terahertz band (for example, 95GHz to 3THz bands). It is expected that, due to severer path loss and atmospheric absorption in the terahertz bands than those in mmWave bands introduced in 5G, technologies capable of securing the signal transmission distance (that is, coverage) will become more crucial. It is necessary to develop, as major technologies for securing the coverage, radio frequency (RF) elements, antennas, novel waveforms having a better coverage than orthogonal frequency division multiplexing (OFDM), beamforming and massive multiple input multiple output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, and multiantenna transmission technologies such as large-scale antennas. In addition, there has been ongoing discussion on new technologies for improving the coverage of terahertz-band signals, such as metamaterial-based lenses and antennas, orbital angular momentum (OAM), and reconfigurable intelligent surface (RIS).

[0006] Moreover, in order to improve the spectral efficiency and the overall network performances, the following technologies have been developed for 6G communication systems: a full-duplex technology for enabling an uplink transmission and a downlink transmission to simultaneously use the same frequency resource at the same time; a network technology for utilizing satellites, high-altitude platform stations (HAPS), and the like in an integrated manner; an improved network structure for supporting mobile base stations and the like and enabling network operation optimization and automation and the like; a dynamic spectrum sharing technology via collison avoidance based on a prediction of spectrum usage; an use of artificial intelligence (AI) in wireless communication for improvement of overall network operation by utilizing AI from a designing phase for developing 6G and internalizing end-to-end AI support functions; and a next-generation distributed computing technology for overcoming the limit of UE computing ability through reachable super-high-performance communication and computing resources (such as mobile edge computing (MEC), clouds, and the like) over the network. In addition, through designing new protocols to be used in 6G communication systems, developing mecahnisms for implementing a hardware-based security environment and safe use of data, and developing technologies for maintaining privacy, attempts to strengthen the connectivity between devices, optimize the network, promote softwarization of network entities, and increase the openness of wireless communications are continuing.

[0007] It is expected that research and development of 6G communication systems in hyper-connectivity, including person to machine (P2M) as well as machine to machine (M2M), will allow the next hyper-connected experience. Particularly, it is expected that services such as truly immersive extended reality (XR), high-fidelity mobile hologram, and digital replica could be provided through 6G communication systems. In addition, services such as remote surgery for security and reliability enhancement, industrial automation, and emergency response will be provided through the 6G communication system such that the technologies could be applied in various fields such as industry, medical care, automobiles, and home appliances.

[0008] According to an aspect of the disclosure, a method of operating a User Equipment, operably connected to a terrestrial telecommunication network, for mobility to an Air to Ground (ATG) telecommunication network is provided. The method may comprise receiving ATG assistance information for performing measurements of an ATG cell in the ATG telecommunication network; performing measurement of the ATG cell; and performing mobility to the ATG cell.

[0009] According to an aspect of the disclosure, a user equipment (UE) operably connected to a terrestrial telecommunication network, for mobility to an air to ground (ATG) telecommunication network is provided. The UE may comprise a transceiver; and at least one processor coupled to the transceiver. The processor is configured to: receive ATG assistance information for performing measurements of an ATG cell in the ATG telecommunication network; perform measurement of the ATG cell; and perform mobility to the ATG cell.

[0010] Although a few embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

[0011] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which:

[0012] Figure 1 illustrates a Non-Terrestrial Network (NTN), according to an embodiment of the disclosure;

[0013] Figure 2 illustrates an Air to Ground (ATG) Network, according to an embodiment of the disclosure;

[0014] Figure 3 illustrates a handover procedure, according to an embodiment of the disclosure ;

[0015] Figure 4 illustrates a mobility from a terrestrial network to an ATG network, according to an embodiment of the disclosure;

[0016] Figure 5 illustrates a call flow for broadcasted configuration providing ATG neighbour cell assistance information for connected mode handovers according to an embodiment of the disclosure;

[0017] Figure 6 illustrates a call flow for dedicated configuration of ATG assistance information in a measurement configuration for connected mode handovers according to an embodiment of the disclosure;

[0018] Figure 7 illustrates a call flow for redirecting to ATG by configuring ATG assistance information in a RRCRelease message according to an embodiment of the disclosure; and

[0019] Figure 8 illustrates a call flow for indicating capability to perform mobility from a TN cell to an ATG cell according to an embodiment of the disclosure.

[0020] Figure 9 illustrates a structure of a BS, according to an embodiment of the disclosure.

[0021] Figure 10 illustrates a structure of a UE, according to an embodiment of the disclosure.

[0022] Throughout the disclosure, the expression "at least one of a, b or c" indicates only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.

[0023] Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings. As the present description allows for various changes and numerous embodiments of the disclosure, certain embodiments of the disclosure will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the embodiments of the disclosure, and it will be understood that the disclosure includes all modifications, equivalents, and substitutes falling within the spirit and scope of various embodiments of the disclosure. In this disclosure, "examples" and "embodiments" may be used interchangeably. "telecommunication network" and "wireless communication system" may be used interchangeably.

[0024] In describing embodiments of the disclosure, when the detailed description of the relevant known functions or configurations is determined to unnecessarily obscure the gist of the disclosure, the detailed description thereof may be omitted herein. Furthermore, numbers (e.g., first, second, etc.) used in the description of the specification are merely identification symbols for distinguishing one element from another.

[0025] As for the terms as used in embodiments of the disclosure, common terms that are currently widely used are selected as much as possible while taking into account the functions of the disclosure. However, the terms may vary depending on the intention of those of ordinary skill in the art, precedents, the emergence of new technology, and the like. Also, in a specific case, there are also terms arbitrarily selected by the applicant. In this case, the meaning of the terms will be described in detail in the description of embodiments of the disclosure. Therefore, the terms as used herein should be defined based on the meaning of the terms and the description throughout the disclosure rather than simply the names of the terms.

[0026] The scope of the disclosure may be defined by the appended claims rather than the detailed description. Various features stated in one claim category (e.g., a method claim) of the disclosure may also be claimed in other claim categories (e.g., a system claim). In addition, an embodiment of the disclosure may include various combinations of individual features within the claims as well as combinations of features specified in the appended claims. All changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as falling within the scope of the disclosure.

[0027] Also, when one element is referred to as being "connected" or "coupled" to another element, the one element may be directly connected or coupled to the other element, but it will be understood that the elements may be connected or coupled to each other via an intervening element therebetween unless otherwise stated. Also, when one element is referred to as being "directly connected" or "physically connected" to another element, it will be understood that the one element may be "electrically connected to" the other element with an intervening element there between. Throughout the disclosure, the terms "transmit," "receive," and "communicate" may include both direct communication and indirect communication. Throughout the disclosure, the expression "a portion includes a certain element" means that a portion further includes other elements rather than excludes other elements unless otherwise stated.

[0028] Also, an element represented by "unit," "module," etc. in the disclosure may be one element in which two or more elements are combined, or may be divided into two or more element for each more subdivided function. These functions may be implemented as hardware or software, or may be implemented as a combination of hardware and software. Also, each of the elements to be described below may additionally perform, in addition to the main function thereof, some or all of the functions that other elements are responsible for, and some of the main functions that the respective elements are responsible for may be dedicated by other elements.

[0029] The singular forms as used herein are intended to include the plural forms as well unless the context clearly indicates otherwise. All terms including technical or scientific terms as used herein have the same meaning as commonly understood by those of ordinary skill in the art.

[0030] Throughout the disclosure, the term "or" is inclusive and not exclusive unless otherwise stated. Therefore, the expression "A or B" may indicate "A," "B," or "both A and B" unless the context clearly indicates otherwise. Throughout the disclosure, the expression "at least one of" or "one or more of" refer to a case where different combinations of one or more of the listed items may be used, or only one of the listed items is required. For example, the expression "at least one of A, B, and C" may include only A, only B, only C, A and B, A and C, B and C, or all of A, B, and C.

[0031] It will be understood that the respective blocks of flowcharts and combinations of the flowcharts may be performed by computer program instructions. Because these computer program instructions may be embedded in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatuses, the instructions to be executed through the processor of the computer or other programmable data processing apparatus generate modules for performing the functions described in the flowchart block(s). Because these computer program instructions may also be stored in a computer-executable or computer-readable memory that may direct the computer or other programmable data processing apparatus so as to implement functions in a particular manner, the instructions stored in the computer-executable or computer-readable memory are also capable of producing an article of manufacture containing instruction modules for performing the functions described in the flowchart block(s). Because the computer program instructions may also be embedded in the computer or other programmable data processing apparatus, the instructions for executing the computer or other programmable data processing apparatuses by generating a computer-implemented process by performing a series of operations on the computer or other programmable data processing apparatuses may provide operations for executing the functions described in the flowchart block(s).

[0032] Also, each block may represent part of a module, segment, or code that includes one or more executable instructions for executing a specified logical function(s). It should also be noted that, in some alternative implementations, the functions described in the blocks may occur out of the order noted in the drawings. For example, two blocks illustrated in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in a reverse order, depending on the functions involved therein.

[0033] Hereinafter, embodiments of the disclosure will be described with reference to the accompanying drawings, so that those of ordinary skill in the art may easily carry out the disclosure. However, the disclosure may be implemented in various different forms and is not limited to the embodiments described herein. In order to clearly explain the disclosure, parts irrelevant to the description are omitted in the drawings, and similar reference numerals are assigned to similar parts throughout the specification.

[0034] Also, although a long-term evolution (LTE), LTE-A, LTE Pro, or 5th generation (5G) system is described below as an example, the embodiments of the disclosure may also be applied to other communication systems having technical backgrounds or channel forms similar thereto. For example, 5G-Advance or 6th generation (6G) (beyond 5G), which has been developed after 5G mobile communication technology (NR), may be included, and the 5G may be a concept including the existing LTE, LTE-A, and other similar services. Also, the disclosure may also be applied to other communication systems through some modifications without departing from the scope of the disclosure.

[0035] Terms as used herein are briefly described, and an embodiment of the disclosure are described in detail.

[0036] Terms as used herein are those defined by taking into account the functions in the disclosure, but the terms may vary depending on the intention of users or those of ordinary skill in the art, precedents, or the like. Therefore, the definitions should be made based on the contents throughout the specification.

[0037] In the disclosure, a base station is configured to perform resource allocation of a user equipment (UE), and may be at least one of a gNode B, an eNode B, a Node B (or xNode B (x is an alphabet including g and e)), a base station (BS), non-terrestrial network (NTN) gNB, terrestrial network gNB, air to ground (ATG) newtork gNB, ground base station, a radio access unit, a base station controller, a satellite, an airborn, RAN node, access point, wireless point, transmission / reception point, central unit, distributed unit, radio unit, remote radio head or a node on a network, but the disclosure is not limited thereto. The base station in the disclosure may refer to a base station itself, a cell, or a radio unit (RU) according to interpretation, and a target for exchanging messages with the UE may be a distributed unit (DU) or a central unit (CU) according to a structure.

[0038] Also, in the disclosure, the UE may include a mobile station (MS), a cellular phone, a smartphone, a computer, a vehicle, a satellite, IAB-MT, mIAB-MT, NCR-MT, electronic device, user device, mobile station, subscriber station, customer premises equipment, terminal, remote terminal, wireless terminal, vehicle terminal, aircraft or a multimedia system capable of performing a communication function.

[0039] Also, in the disclosure, the cell may represent an area covered by one base station in wireless communication. Cells may be classified into mega cells, macro cells, micro cells, and pico cells according to sizes thereof, but this is only an example, and the types of cells are not limited thereto.

[0040] Also, in the disclosure, the DU may be connected to the RU and the CU and execute some of radio link control (RLC), medium access control (MAC), and physical (PHY) layers. In an embodiment of the disclosure, a virtualized DU may be included.

[0041] Also, in the disclosure, the CU may include radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) layers. One CU may manage one or more DUs, and may be connected to the one or more DUs through an F1 interface. In an embodiment of the disclosure, a virtualized CU may be included.

[0042] Also, in the disclosure, the RU may convert a radio signal into a digital signal for the purpose of transmission through a packet network.

[0043] In addition, in the disclosure, a downlink (DL) is a radio transmission path through which the base station transmits data or a control signal to the UE. For example, in the LTE system, the DL may employ an orthogonal frequency division multiplexing (OFDM) scheme.

[0044] In addition, in the disclosure, an uplink (UL) refers to a radio transmission path through which the UE transmits data or a control signal to the base station. For example, in the LTE system, the UL may employ a single carrier frequency division multiplexing access (SC-FDMA) scheme.

[0045] For convenience of description, the terms and names defined in the 3rd generation partnership project long term evolution (3GPP) standard or the terms and names modified based thereon are used herein.

[0046] However, the disclosure is not limited by the terms and names and may be equally applied to wireless communication systems conforming to other standards. Although an embodiment of the disclosure will be described below with reference to a 5G wireless communication technology as an example, an embodiment of the disclosure may also be applied to other wireless communication systems having technical backgrounds or channel forms similar thereto. As another example, the embodiments of the disclosure may be applied to LTE or LTE-A, which is a wireless communication system prior to NR, and may also be applied to a wireless communication system developed after NR. Furthermore, it will be understood by those of ordinary skill in the art that the embodiments of the disclosure may also be applied to other wireless communication systems through partial modifications without departing from the scope of the disclosure.

[0047] The embodiments of the disclosure may also be applied to other wireless communication systems through modifications.

[0048] New Radio Non-Terrestrial Networks, NR NTN, (NR_NTN_solutions-Core) [defined in 3GPP document RP-211557] was a 3GPP Work Item in 3GPP Release 17 to define solutions to enable New Radio (NR) and Next Generation Radio Access Network, NG-RAN, to support Non-Terrestrial Networks. It addressed solutions for Transparent payload for both Geostationary and non-Geostationary network scenarios, with the User Equipment, UE, having Global Navigation Satellite System, GNSS, capability and the satellite beams being both earth-fixed or earth-moving.

[0049] Internet of Things, IoT NTN, was a 3GPP study and work item in 3GPP release 17 to provide Non-Terrestrial Network access for E-UTRAN IoT devices (NB-IoT and LTE-M / eMTC) [3GPP document RP-202689]. NR NTN was a work item in Rel-17 to specify adaptation to allow NR to function over NTN [3GPP document RP-211557]. Non-Terrestrial Network access may be through Lower Earth Orbit (LEO), Medium Earth Orbit (MEO) and Geostationary Orbit (GEO), as well as through High-Altitude Platform Systems (HAPS).

[0050] Following the Work items in Release 17 there were work items to enhance NR NTN and IoT NTN in Release 18 of the standard specification.

[0051] According to embodiments of the disclosure, NR NTN enhancements in 3GPP Release 18 may be achieved by enhancing NR NTN with the following topics:

[0052] > Coverage enhancements

[0053] >>Identifying and specifying potential issues and enhancements considering NTN characteristics

[0054] > NR NTN deployment in above 10 GHz bands

[0055] >>NR NTN Release 17 did not have support for Frequency Range 2, FR2, due to there being no Physical Radio Access Channel, PRACH, format in FR2 for Frequency Division Duplexing, FDD.

[0056] > Network verified UE location

[0057] > NTN-TN and NTN-NTN mobility and service continuity enhancements

[0058] >>Considers NTN-TN and NTN-NTN measurement / mobility and service continuity enhancements

[0059] Synchronization in NR NTN is partly achieved by the UE computing the distance between the UE and the NTN node. To do this the UE needs to know its own position as well as the position of the satellite. UE acquires its own position through GNSS and the satellite position through what is known as the satellite ephemeris element, broadcast in System Information, SI. As both UE and satellite may move, this is maintained in two ways, through 1) maintaining an accurate GNSS position, 2) maintaining a recent ephemeris element of the serving satellite.

[0060] In NR NTN, the satellite ephemeris is broadcast in system information block SIB19. This element needs to be acquired every time the UE attempts to connect to an NTN cell. SIB19 also contains neighbour cell assistance information.

[0061] In IoT NTN the serving cell ephemeris element is sent in system information in an element known as SIB31 and, in order to make sure that the UE is correctly synchronized, this element needs to be read every time it connects to an IoT NTN e-Node B, eNB.

[0062] Figure 1 illustrates a Non-Terrestrial Network (NTN), according to an embodiment of the disclosure.

[0063] Figure 1 shows an NTN cell 10, which is comparatively larger than a terrestrial cell. A UE 20 in the NTN cell is able to communicate with a satellite 30, which in turn communicates with a ground station 40, which forms part of a g-Node B 50 and thence onto the Core Network 60

[0064] An Air-To-Ground (abbreviated as ATG or A2G) network is a cellular network that provides connectivity in the air via base stations on the ground. It is different from a Non-Terrestrial Network, as the access link is from the ground to the UE in the sky (e.g on an aircraft), as seen in Figure 2. In contract, in NTN, the access link is from space / sky to the ground.

[0065] Figure 2 illustrates an Air to Ground (ATG) Network, according to an embodiment of the disclosure.

[0066] Figure 2 shows two ATG cells 100, 101, each connected to a ground base station 110, 111 respectively. Each of these is connected to the Core Network 120. In ATG cell 101, there is a UE 130

[0067] One of the main the use cases of A2G network is to provide backhaul connectivity to access points in aircraft.

[0068] Work has been ongoing to define requirements for coexistence between ATG and International Mobile Telecommunications, IMT, terrestrial networks. Furthermore, work is ongoing to define Radio resource management, RRM, performance requirements for ATG UEs, demodulation performance requirements for ATG BS / UE, and test procedures for ATG BS conformance testing.

[0069] The Air-To-Ground network is similar to a Non-terrestrial network in the sense that the cells can be very large, synchronization will have to be different to terrestrial cases and that there are network elements that may move very quickly.

[0070] Some of the characteristics, from an RF point of view, of an ATG network include:

[0071] 1. Extremely large inter-site distances and large coverage range

[0072] 2. Utilizing non-disjoint frequency for deploying both ATG and terrestrial networks

[0073] 3. Much more powerful on-board ATG terminal capacity

[0074] In order to allow for an ATG-capable UE to connect to an ATG cell, the UE needs certain information, similar to NR NTN.

[0075] In ATG, the UE is provided via system information in SIB22 with the following information:

[0076] > ATG-Config, which contains the following information:

[0077] >> atg-gNB-Location and heightgNB, which is required in order for a UE to synchronize with the ATG cell. Atg-gNB-Location is a refence location that defines a coordinate on the surface of the earth, while the height is a number having a granularity of 1 metre. Both elements may be purposefully obscured, i.e not showing the true position, in order to not give up the precise location of the gNB, which can be sensitive information for a network operator.

[0078] >> Cell specific Koffset

[0079] >Ta-ReportATG - This indicates whether a Timing Advance Report Media Access Control, Control Element, MAC CE, should be triggered, compiled and sent to the network under certain conditions such as during random access procedures, handovers and Radio Resource Control, RRC, connection establishment, RRC Resume or RRC Connection re-establishment.

[0080] The above set of parameters may be referred to as "ATG assistance information". However, it is expected that any future parameters that are included in ATG-Config would also be characterized as ATG assistance information.

[0081] The 5G NR connected mode mobility functions similar to other cellular standards. A standard connected mode handover is performed only when triggered by the gNB.

[0082] Figure 3 illustrates a handover procedure, according to an embodiment of the disclosure

[0083] The full usual procedure is as follows and as illustrated in Figure 3:

[0084] S1) A UE 200 is configured with measurement configuration via RRCReconfiguration, which includes a MeasReportNR which instructs when a UE shall report measurements and also includes the MeasObjectNR which gives details on how to perform the measurement.

[0085] S2) UE 200 performs neighbour cell measurements according to the measurement configuration, which are configured by the network.

[0086] S3a) A measurement report (of a neighbour cell) is triggered and,

[0087] S3b) The measurement report is sent to the gNB 210.

[0088] S4) Inter-node procedures whereby the Source gNB 210 sends a Handover Request to Target gNB 220 after having decided whether to trigger a handover and the target gNB 220 sends a Handover Request Acknowledge to Source gNB 210.

[0089] S5) The Source gNB 210 triggers a handover command which is sent to the UE 200. This handover command consists of the RRC message RRCConnectionReconfiguration, containing the mobilityControlInfo field.

[0090] S6) UE 200 prepares for handover to the target gNB 220 and performs a handover via the random access procedure.

[0091] A measurement configuration consists of a set of measurement objects and measurement reporting configuration for RRM purposes. These measurement objects define the configurations of the measurements that a UE shall perform in RRC connected mode.

[0092] A measurement object is related to either a frequency or a Radio Access Technology, RAT. There is, for instance, an intra-RAT NRMeasurement object (MeasObjectNR), which may configure intra or inter-frequency measurements. The MeasObjectNR contains configurations such as the carrier frequency, measurement bandwidth, SSB configurations, neighbour cell configurations, specific cells to measure, cells not to measure and report and many more configurations. There are also Inter-RAT measurement object that contains all of the necessary configurations to perform connected mode measurements of E-UTRAN (MeasObjectEUTRA), UTRA (MeasObjectUTRA), GERAN (MeasObjectGERAN), CDMA2000 (MeasObjectCDMA2000), or WLAN (MeasObjectWLAN).

[0093] The measurement reporting configuration contains rules that define when a measurement report containing measurements shall be sent. These are typically defined by measurement reporting triggering conditions (also called measurement events), thresholds, and configuring what measure shall be reported.

[0094] Idle and inactive mode mobility is based on a UE autonomously performing measurements and deciding, according to some rules, whether a UE shall re-select to another cell or not to camp on.

[0095] During cell selection, the UE identifies suitable cells, which is done according to a cell suitability criteria based on signal strength and signal quality measurements. After identifying one or several suitable cells, the UE can choose any of them.

[0096] During cell re-selection, the UE searches intra-frequency cells, inter-frequencies cells and inter-RAT cells. Each frequency will have a specific cell reselection priority, and the UE shall always choose a cell of highest priority, provided that it is not barred or not allowed to camp on. If cells of equal priority are detected, then the UE shall rank all of the cells, where the ranking metric is based on signal strength and signal quality measurements and then choose the best candidate. The UE then camps on the newly re-selected cell.

[0097] The distances in an ATG network are considerably larger than those experiences in a terrestrial network, where the vertical distance may be more than 10km and the horizontal distance is a maximum of 100km. This means that the propagation delay is larger than a terrestrial network is designed to handle. To mitigate this issue, and avoid re-designing the 5G NR air interface to handle this, the ability of the UE to self-compensate was introduced. This self-compensation is done by the UE calculating the distance between the UE and an ATG cell and then compensating the timing and the considerable doppler shift (created by the rapid movement of an aircraft). This requires the UE to acquire its own UE position, for instance via GNSS, and also to acquire the position of the ATG gNB. This is provided for both serving cell, which is used for accessing a cell, and also for neighbouring cells, which is used for neighbour cell measurements. In the related art, the already described ATG assistance information has only been introduced in an ATG cell.

[0098] However, in many use cases, such as in aviation, the aircraft also requires connectivity on the ground, when it is not connected to an ATG cell. This is used, for instance, for uploading aircraft maintenance and analytics data etc. This means that some form of service continuity is needed between a terrestrial and an ATG network, as seen in Figure 4.

[0099] Figure 4 illustrates a mobility from a terrestrial network to an ATG network, according to an embodiment of the disclosure

[0100] However, for the service continuity to function, there needs to be a means to allow for assistance information to be configured. This is because without assistance information being provided, the mobility between a Terrestrial Network, TN, and an ATG will face severe difficulties. For instance, the UE may not be able to measure an ATG cell while in RRC_CONNECTED mode. Further, in idle or inactive mode the UE may have difficulty detecting an ATG cell, potentially also leading to measurements failing.

[0101] According to the present disclosure there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

[0102] According to an aspect of the present disclosure there is provided a method of operating a User Equipment, operably connected to a terrestrial telecommunication network, for mobility to an Air to Ground, ATG, telecommunication network, comprising the steps of: receiving ATG assistance information for performing measurements of an ATG cell in the ATG telecommunication network; performing measurement of the ATG cell; and performing mobility to the ATG cell.

[0103] In an embodiment of the disclosure, the ATG assistance information is received in broadcasted information from the terrestrial telecommunication network.

[0104] In an embodiment of the disclosure, the ATG assistance information is received in a measurement configuration, transmitted from the terrestrial telecommunication network.

[0105] In an embodiment of the disclosure, the ATG assistance information is received, from the terrestrial telecommunication network, in an RRC release message.

[0106] In an embodiment of the disclosure, the UE performs mobility to the ATG cell based on receiving an RRC release with redirection from the terrestrial network.

[0107] In an embodiment of the disclosure, the UE additionally performs at least one neighbour cell measurement.

[0108] In an embodiment of the disclosure, the UE sends a measurement report based on measuring an ATG cell using the ATG assistance information.

[0109] In an embodiment of the disclosure, the UE performs mobility to the ATG cell based on receiving a handover command from the terrestrial network.

[0110] According to an aspect of the present disclosure there is provided apparatus arranged to perform the method of the first aspect.

[0111] Embodiments of the disclosure provide a method for configuring a UE with ATG assistance information in order to perform TN to ATG mobility.

[0112] Herein, the notion of ATG network and network may be used interchangeably. In other words a "network" should not be taken to necessarily mean a non-ATG network.

[0113] In terms of base stations, the term "gNB" may be interchanged with a BS / eNB / NG-RAN / NG-eNB or similar. This further means that methods according to the disclosure are not limited to 5G NR, but also 4G E-UTRAN including IoT technologies such as eMTC or NB-IoT. It is applicable to IoT NTN, which is based on 4G E-UTRAN as well.

[0114] In terms on the wireless device, ATG UE and UE may refer to the same type of wireless device. In other words a "UE" should not be interpreted to mean a "non-ATG UE". ATG UE may also be considered a "ATG-capable UE". It should be noted that in some parts of this application, the ATG UE may be referred to as "UE".

[0115] Herein, the term "terrestrial network" is used to refer to a network that is not an ATG network, but terms may for instance be "non-ATG network". While the methods herein refer to "terrestrial network" as a "non-ATG network", the network may also be a "non-terrestrial network". In other words, methods for performing mobility from a network located on the ground for the purpose of serving terrestrial UEs to an ATG network may also be applicable for the mobility from a network where one or several network elements are non-terrestrial for the purpose of serving terrestrial UEs or UEs in the air to an ATG network. This may be particularly useful in providing service to aircraft, where when the ATG UE flies over land, the service would be provided by an ATG network, and when the ATG UE flies over sea, the service is provided by NTN.

[0116] To allow for a UE to monitor ATG cell(s) while not connected to the ATG network, there is a need for a UE to synchronize to these cells in order to measure them.

[0117] In an embodiment of the disclosure, the terrestrial network provides ATG assistance information for ATG cells or ATG frequencies, to allow for the UE to synchronize to measure the ATG cells.

[0118] This can for instance be used during mobility events where for instance an airplane takes off and is connected to a ground network.

[0119] In an embodiment of the disclosure, the ATG assistance information is provided in a broadcast fashion, i.e via System Information. This method is beneficial as it allows UEs both in connected mode as well as in idle and inactive mode to synchronize and measure ATG cells.

[0120] In an embodiment of the disclosure, the ATG assistance information is provided in ATG SIB22. This system information is used in an ATG cell to provide ATG serving cell and ATG neighbouring cell information.

[0121] Further, when a terrestrial network broadcasts the ATG SIB22, the network does not provide a serving cell ATG configuration (atg-Config). This may indicate to an ATG UE that the cell in question is not an ATG cell, but rather a terrestrial cell that is providing ATG assistance information for neighbouring ATG cells. Another condition to identify that the terrestrial cell is not an ATG network is that neighbour cell ATG assistance information is configured (atg-NeighCellConfigList), but not the serving cell ATG assistance information (atg-Config).

[0122] The broadcasted ATG assistance information may be stored in ATG UE memory even if the UE is no longer connected or camping on the ATG cell. This is useful in case the signal connection is no longer sufficient when the ATG-capable UE is in the air and the connection breaks.

[0123] Figure 5 illustrates a call flow for broadcasted configuration providing ATG neighbour cell assistance information for connected mode handovers according to an embodiment of the disclosure

[0124] The broadcast ATG assistance information can be used in both connected mode as well as in idle and inactive mode. An example of how it can be used in connected mode can be seen in Figure 5, which shows messages exchanged between a UE 300, a source TN gNB 310 and a Target ATG gNB 320.

[0125] In this case for connected mode at least one of the following steps are performed:

[0126] S11. The terrestrial source cell or TN gNB 310 signals the ATG neighbour cell assistance information in a SIB22, which the UE 300 acquires.

[0127] S12. Configure the measurement of ATG neighbouring cells. In this case the UE 300 can identify which cells or frequencies belong to which ATG assistance information by using the signalled frequency or the Cell ID.

[0128] S13. Using the measurement configuration as well as the broadcasted ATG neighbour cell assistance information, the UE 300 performs measurements on the configured ATG cells.

[0129] S14. If the measurement is performed and evaluated to satisfy a configured condition in a reporting configuration (ReportConfigNR), the UE 300 reports the measurements to the source TN gNB 310.

[0130] S15. Handover command sent to the UE300 to perform a handover towards an ATG cell, which is performed if the source TN gNB 310 has decided that it would be suitable to perform the handover. This would also include network inter-node signalling between gNBs. This handover command may consist of the RRC message RRCConnectionReconfiguration, containing the mobilityControlInfo field

[0131] S16. Handover is performed to the target ATG gNB 320.

[0132] In the foregoing, mobility from a terrestrial NR cell to an NR ATG cell has been described. It may also be possible to perform mobility from a terrestrial E-UTRAN cell to an NR ATG cell. This can, for instance, be done by configuring the ATG assistance information in a SIB that is used for Inter-RAT mobility for NR, which would be SIB24 (SystemInformationBlockType24). Alternatively a new SIB specifically for ATG assistance information may be introduced.

[0133] In an embodiment of the disclosure, the ATG assistance information can be configured in a dedicated fashion to allow for a UE to synchronize and measure an ATG cell.

[0134] This can be configured in a measurement configuration, such as MeasObjectNR in MeasConfig, and be configured per cell or per frequency. If it is configured per cell, then there may be a single ATG assistance information element per cell, and if it is configured per frequency, then there may be a list of ATG assistance information elements.

[0135] In an embodiment of the disclosure, a UE that is connected to an E-UTRAN cell may be provided with ATG assistance information. This may be configured in a MeasObjectNR in the E-UTRAN NR inter-RAT measurement configuration

[0136] Dedicated configuration is usually associated with connected mode mobility, but there may also be the possibility of configuring dedicated configurations to be used in inactive mode.

[0137] In an embodiment of the disclosure, the UE can be configured with dedicated ATG assistance information to be used in RRC inactive. This can be configured as part of suspendConfig as part of RRCRelease. The messages S21 - S25 exchanged in this embodiment are as shown in Figure 6.

[0138] Figure 6 illustrates a call flow for dedicated configuration of ATG assistance information in a measurement configuration for connected mode handovers according to an embodiment of the disclosure. For ease of explanation, some content corresponding to Figure 5 may be omitted.

[0139] In this case at least one of the following steps are performed:

[0140] S21.The terrestrial source cell or source TN gNB 410 configures measurement of ATG neighbor cells by signaling the ATG neighbour cell assistance information, which the UE 400 acquires. The ATG neighbour cell assistance information may be included in suspendConfig as part of RRCRelease.

[0141] S22. The UE 300 performs neighbor cell measurements of ATG cells using ATG neighbor cell assistance information.

[0142] S23. The measurement report of ATG cell (MeasurementReport) is sent from the UE 400 to the source TN gNB 410. If the measurement is performed and evaluated to satisfy a configured condition in a reporting configuration (ReportConfigNR), the UE 400 may report the measurements to the source TN gNB 410.

[0143] Inter-node procedures whereby the Source TN gNB 410 sends a Handover Request to Target ATG gNB 420 after having decided whether to trigger a handover and the target ATG gNB 420 sends a Handover Request Acknowledge to Source TN gNB 410.

[0144] S24. Handover command sent from Source TN gNB 410 to the UE 400 to perform a handover towards an ATG cell, which is performed if the source TN gNB 410 has decided that it would be suitable to perform the handover. This may also include network inter-node signalling between gNBs. This handover command may consist of the RRC message RRCConnectionReconfiguration, containing the mobilityControlInfo field

[0145] S25. Handover is performed to the target ATG gNB 420. UE 400 may prepare for handover to the target gNB 220 and performs a handover via the random access procedure. Figure 7 illustrates a call flow for redirecting to ATG by configuring ATG assistance information in a RRCRelease message according to an embodiment of the disclosure

[0146] Re-direction is a type of idle mode mobility where the UE is told to move to a certain frequency and perform cell selection. This does not require the UE to first measure on the frequency and, therefore, it requires less configuration and setup compared to a network-directed or network-controlled mobility procedure.

[0147] In an embodiment of the disclosure, a network may re-direct an ATG UE from a terrestrial network to an ATG network.

[0148] As part of this re-direction, the UE may be configured with ATG assistance information to better allow a UE to synchronize to a cell on the frequency. This ATG assistance information may be a set of ATG assistance information for a number of cells, base stations or gNBs, or may also only be a single ATG assistance information element for a single cell, a single base station or a single gNB.

[0149] When the UE receives an ATG RRCRelease message indicating redirection with ATG assistance information, the UE will tune over to the new indicated frequency, perform cell selection and then select an ATG cell. The full procedures can be seen in Figure 7, which shows message S31 to S35.

[0150] In this case at least one of the following steps are performed:

[0151] S31. Network or TN gNB 510 decides to release an ATG-capable UE to an ATG gNB, ATG cell or ATG frequency.

[0152] S32. TN gNB 510 send RRCRelease with redirectionInfo containing ATG assistance information.

[0153] S33 The UE 500 perform cell selection using on the ATG frequency using the ATG assistance information.

[0154] S34. The UE 500 select and camp on the ATG gNB.

[0155] S35. Connection to ATG gNB is established.

[0156] Figure 8 illustrates a call flow for indicating capability to perform mobility from a TN cell to an ATG cell according to an embodiment of the disclosure

[0157] In order to allow for a UE to perform mobility from a TN to an ATG network, the ATG cell needs to have knowledge of the capabilities of the ATG-capable UE for performing mobility. Figure 8 shows a message flow diagram related to a UE indicating capability to perform mobility from a TN cell to an ATG cell. Message S41 is sent from UE 500 to Source TN gNB 510 indicating TN to ATG capabilities. Information indicating ATG capabilities may be included in the message S41

[0158] ATG measurement and handover is performed. For ease of explanation, some content corresponding to Figure 5 or Figure 6 may be omitted.

[0159] In an embodiment of the disclosure, the UE reports to a terrestrial network its capabilities to perform mobility from a terrestrial to an ATG network. The capabilities may have the following options:

[0160] > Reporting that the ATG-capable UE is capable of performing idle and inactive mode mobility from a terrestrial cell to an ATG cell

[0161] >> As part of this capability, the UE may report that it is capable of reading, processing and utilizing the ATG assistance information for measurement purposes.

[0162] > Reporting that the ATG-capable UE is capable of performing connected mode measurements and connected mode handovers to an ATG cell

[0163] >> Whether UE is capable of reading, processing and utilizing ATG dedicated assistance information for measurement purposes

[0164] >> Whether UE is capable of reading, processing and utilizing ATG broadcasted (for instance in a SIB22 broadcasted by a terrestrial cell) assistance information for measurement purposes

[0165] > Reporting that the ATG-capable UE is capable of performing re-direction from a terrestrial to an ATG network

[0166] >> Whether UE is capable of reading, processing and utilizing ATG assistance information provided in an RRCRelease message.

[0167] Furthermore, if there is a significant change in frequency from the terrestrial network to the ATG network, the capabilities of the UE to perform a handover also involving a significant change in carrier frequency may be reported. Some options include:

[0168] > Whether the UE is capable of measuring inter-frequencies and performing inter-frequency handover

[0169] >> Whether the UE can perform measurements and handover from a terrestrial Frequency Range 1 (FR1) cell to ATG FR1 cell

[0170] As the ATG network is a network that operates from 3000 metres up to altitudes of above 10000 metres, the UE should not be connected to an ATG before reaching the 3000 metre altitude.

[0171] As the network may not know the exact height of the aircraft in order to configure a UE to measure once the UE is above 3000 metres, it may instead be useful for the UE to autonomously start measuring once the UE is above 3000 metres.

[0172] Therefore, in an embodiment of the disclosure, if the UE is configured in connected mode to measure ATG cells, the UE does not start measuring any of the cells before the UE is above 3000 metres. This can be done without any explicit configuration but would rather be a default action. In an alternative, it can be explicitly configured, i.e that a field indicates whether a UE should measure only after or before the ATG-capable UE has reached 3000 metres. This can be a dedicated configuration or a broadcast configuration.

[0173] Similarly, for idle and inactive mode mobility, the UE may not initiate measurement of ATG neighbouring cells before the UE has reached 3000 metres. This can be specified in one of the following ways:

[0174] > When the UE is below the height threshold, the UE considers the cell to be barred and thus not allowed to be accessed and shall not be considered in cell reselection and cell selection procedures.

[0175] > The UE may consider ATG cells to be part of exclude list and not part of allowed list when the UE is below the height threshold

[0176] > Only higher priority or equal priority frequencies with ATG cells may be measured when the UE is below the height threshold, and the ATG cells that are lower priority frequencies are not required to be measured.

[0177] The height for the above configuration may be configurable, i.e while the UE may not be allowed to connect to an ATG cell before 3000 metres, the UE may be configured to be allowed to measure the ATG cell before 3000 metres. As an example, the UE may be allowed to start measuring at 2000 metre altitude in order for timely mobility.

[0178] The following illustrates ways in which the relevant 3GPP specification may be amended to reflect the developments introduced herein.

[0179] 38.331 V18.0.0 EXAMPLE

[0180] -SIB22

[0181] SIB22contains ATG assistant information.

[0182] SIB22information element

[0183] -- ASN1START

[0184] -- TAG-SIB22-START

[0185] SIB22-r18 ::= SEQUENCE {

[0186] atg-Config-r18 ATG-Config-r18 OPTIONAL, -- Need R

[0187] hs-ATG-cellReselectionSet-r18 ENUMERATED {true} OPTIONAL, -- Need R

[0188] atg-NeighCellConfigList-r18 ATG-NeighCellConfigList-r18 OPTIONAL, -- Need R

[0189] lateNonCriticalExtension OCTET STRING OPTIONAL,

[0190] ...

[0191] }

[0192] ATG-NeighCellConfigList-r18 ::= SEQUENCE (SIZE(1..maxCellATG-r18)) OF ATG-NeighCellConfig-r18

[0193] ATG-NeighCellConfig-r18 ::= SEQUENCE {

[0194] atg-gNB-Location-r18 ReferenceLocation-r17 OPTIONAL, -- Need R

[0195] heightgNB-r18 INTEGER (-16384..16383) OPTIONAL, -- Need R

[0196] carrierFreq-r18 ARFCN-ValueNR OPTIONAL, -- Need R

[0197] physCellId-r18 PhysCellId OPTIONAL, -- Need R

[0198] ...

[0199] }

[0200] -- TAG-SIB22-STOP

[0201] -- ASN1STOP

[0202]

[0203] 38.331 V18.0.0 EXAMPLE

[0204] -MeasObjectNR

[0205] The IEMeasObjectNRspecifies information applicable for SS / PBCH block(s) intra / inter-frequency measurements and / or CSI-RS intra / inter-frequency measurements.

[0206] MeasObjectNRinformation element

[0207] -- ASN1START

[0208] -- TAG-MEASOBJECTNR-START

[0209] MeasObjectNR ::= SEQUENCE {

[0210] ssbFrequency ARFCN-ValueNR OPTIONAL, -- Cond SSBorAssociatedSSB

[0211] ssbSubcarrierSpacing SubcarrierSpacing OPTIONAL, -- Cond SSBorAssociatedSSB

[0212] smtc1 SSB-MTC OPTIONAL, -- Cond SSBorAssociatedSSB

[0213] smtc2 SSB-MTC2 OPTIONAL, -- Cond IntraFreqConnected

[0214] refFreqCSI-RS ARFCN-ValueNR OPTIONAL, -- Cond CSI-RS

[0215] referenceSignalConfig ReferenceSignalConfig,

[0216] absThreshSS-BlocksConsolidation ThresholdNR OPTIONAL, -- Need R

[0217] absThreshCSI-RS-Consolidation ThresholdNR OPTIONAL, -- Need R

[0218] nrofSS-BlocksToAverage INTEGER (2..maxNrofSS-BlocksToAverage) OPTIONAL, -- Need R

[0219] nrofCSI-RS-ResourcesToAverage INTEGER (2..maxNrofCSI-RS-ResourcesToAverage) OPTIONAL, -- Need R

[0220] quantityConfigIndex INTEGER (1..maxNrofQuantityConfig),

[0221] offsetMO Q-OffsetRangeList,

[0222] cellsToRemoveList PCI-List OPTIONAL, -- Need N

[0223] cellsToAddModList CellsToAddModList OPTIONAL, -- Need N

[0224] excludedCellsToRemoveList PCI-RangeIndexList OPTIONAL, -- Need N

[0225] excludedCellsToAddModList SEQUENCE (SIZE (1..maxNrofPCI-Ranges)) OF PCI-RangeElement OPTIONAL, -- Need N

[0226] allowedCellsToRemoveList PCI-RangeIndexList OPTIONAL, -- Need N

[0227] allowedCellsToAddModList SEQUENCE (SIZE (1..maxNrofPCI-Ranges)) OF PCI-RangeElement OPTIONAL, -- Need N

[0228] ...,

[0229] [[

[0230] freqBandIndicatorNR FreqBandIndicatorNR OPTIONAL, -- Need R

[0231] measCycleSCell ENUMERATED {sf160, sf256, sf320, sf512, sf640, sf1024, sf1280} OPTIONAL -- Need R

[0232] ]],

[0233] [[

[0234] smtc3list-r16 SSB-MTC3List-r16 OPTIONAL, -- Need R

[0235] rmtc-Config-r16 SetupRelease {RMTC-Config-r16} OPTIONAL, -- Need M

[0236] t312-r16 SetupRelease { T312-r16 } OPTIONAL -- Need M

[0237] ]],

[0238] [[

[0239] associatedMeasGapSSB-r17 MeasGapId-r17 OPTIONAL, -- Need R

[0240] associatedMeasGapCSIRS-r17 MeasGapId-r17 OPTIONAL, -- Need R

[0241] smtc4list-r17 SSB-MTC4List-r17 OPTIONAL, -- Need R

[0242] measCyclePSCell-r17 ENUMERATED {ms160, ms256, ms320, ms512, ms640, ms1024, ms1280, spare1} OPTIONAL, -- Cond SCG

[0243] cellsToAddModListExt-v1710 CellsToAddModListExt-v1710 OPTIONAL -- Need N

[0244] ]],

[0245] [[

[0246] associatedMeasGapSSB2-v1720 MeasGapId-r17 OPTIONAL, -- Cond AssociatedGapSSB

[0247] associatedMeasGapCSIRS2-v1720 MeasGapId-r17 OPTIONAL -- Cond AssociatedGapCSIRS

[0248] ]],

[0249] [[

[0250] measSequence-r18 MeasSequence-r18 OPTIONAL, -- Need R

[0251] cellsToAddModListExt-v1800 CellsToAddModListExt-v1800 OPTIONAL -- Cond ServingCell

[0252] ]],

[0253] [[

[0254] cellsToAddModListExt-v18xy CellsToAddModListExt-v18xy OPTIONAL -- Need N

[0255] ]]

[0256] }

[0257] . . . OMITTED . . .

[0258] CellsToAddModList ::= SEQUENCE (SIZE (1..maxNrofCellMeas)) OF CellsToAddMod

[0259] CellsToAddModListExt-v1710 ::= SEQUENCE (SIZE (1..maxNrofCellMeas)) OF CellsToAddModExt-v1710

[0260] CellsToAddModListExt-v1800 ::= SEQUENCE (SIZE (1..maxNrofCellMeas)) OF CellsToAddModExt-v1800

[0261] CellsToAddModListExt-v18xy ::= SEQUENCE (SIZE (1..maxNrofCellMeas)) OF CellsToAddModExt-v18xy

[0262] CellsToAddMod ::= SEQUENCE {

[0263] physCellId PhysCellId,

[0264] cellIndividualOffset Q-OffsetRangeList

[0265] }

[0266] CellsToAddModExt-v1710 ::= SEQUENCE {

[0267] ntn-PolarizationDL-r17 ENUMERATED {rhcp,lhcp,linear} OPTIONAL, -- Need R

[0268] ntn-PolarizationUL-r17 ENUMERATED {rhcp,lhcp,linear} OPTIONAL -- Need R

[0269] }

[0270] CellsToAddModExt-v1800 ::= SEQUENCE {

[0271] ntn-NeighbourCellInfo-r18 NTN-NeighbourCellInfo-r18 OPTIONAL -- Need R

[0272] }

[0273] CellsToAddModExt-v18xy ::= SEQUENCE {

[0274] atg-NeighbourCellInfo-r18 ATG-Config-r18 OPTIONAL -- Need R

[0275] }

[0276] -- TAG-MEASOBJECTNR-STOP

[0277] -- ASN1STOP

[0278] 38.331 V18.0.0 EXAMPLE

[0279] -RRCRelease

[0280] TheRRCReleasemessage is used to command the release of an RRC connection or the suspension of the RRC connection.

[0281] Signalling radio bearer: SRB1

[0282] RLC-SAP: AM

[0283] Logical channel: DCCH

[0284] Direction: Network to UE

[0285] RRCReleasemessage

[0286] -- ASN1START

[0287] -- TAG-RRCRELEASE-START

[0288] RRCRelease ::= SEQUENCE {

[0289] rrc-TransactionIdentifier RRC-TransactionIdentifier,

[0290] criticalExtensions CHOICE {

[0291] rrcRelease RRCRelease-IEs,

[0292] criticalExtensionsFuture SEQUENCE {}

[0293] }

[0294] }

[0295] RRCRelease-IEs ::= SEQUENCE {

[0296] redirectedCarrierInfo RedirectedCarrierInfo OPTIONAL, -- Need N

[0297] cellReselectionPriorities CellReselectionPriorities OPTIONAL, -- Need R

[0298] suspendConfig SuspendConfig OPTIONAL, -- Need R

[0299] deprioritisationReq SEQUENCE {

[0300] deprioritisationType ENUMERATED {frequency, nr},

[0301] deprioritisationTimer ENUMERATED {min5, min10, min15, min30}

[0302] } OPTIONAL, -- Need N

[0303] lateNonCriticalExtension OCTET STRING OPTIONAL,

[0304] nonCriticalExtension RRCRelease-v1540-IEs OPTIONAL

[0305] }

[0306] . . . OMITTED . . .

[0307] RedirectedCarrierInfo ::= CHOICE {

[0308] nr CarrierInfoNR,

[0309] eutra RedirectedCarrierInfo-EUTRA,

[0310] ...

[0311] }

[0312] . . . OMITTED . . .

[0313] CarrierInfoNR ::= SEQUENCE {

[0314] carrierFreq ARFCN-ValueNR,

[0315] ssbSubcarrierSpacing SubcarrierSpacing,

[0316] smtc SSB-MTC OPTIONAL, -- Need S

[0317] ...,

[0318] [[

[0319] atg-Assistance-r18 SEQUENCE (SIZE (0..maxCellATG-r18)) OF ATG-Config-r18 OPTIONAL -- Need N

[0320] ]]

[0321] }

[0322] . . . OMITTED . . .

[0323] -- TAG-RRCRELEASE-STOP

[0324] -- ASN1STOP

[0325]

[0326] Figure 9 illustrates a structure of a BS, according to an embodiment of the disclosure.

[0327] Referring to FIG. 9, the BS 900 may include a transceiver 910, a processor 920, and a memory 930, which may collectively operate according to a communication method of the BS 900. However, elements of the BS 900 are not limited thereto. For example, the BS 900 may include more or fewer elements than those described above. The transceiver 910, the processor 920, and the memory 930 may be implemented as a single chip and the processor 920 may include one or more processors.

[0328] A receiver and a transmitter of the BS 900 are collectively referred to as the transceiver 910, which may transmit or receive signals (i.e., control information and data) to or from a UE or a network entity. To this end, the transceiver 910 may include an RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and an RF receiver for low-noise amplifying and down-converting a frequency of a received signal. However, this is merely an example of the transceiver 910, and elements of the transceiver 910 are not limited to the RF transmitter and the RF receiver.

[0329] The transceiver 910 may perform functions for transmitting and receiving signals via a wireless channel. For example, the transceiver 910 may receive signals through wireless channels and output the signals to the processor 920, and may transmit signals output from the processor 920 through wireless channels.

[0330] The memory 930 may store a program and data required to operate the BS 900 and may store control information or data included in a signal obtained by the BS. The memory 930 may include a storage medium such as a read-only memory (ROM), a random-access memory (RAM), a hard disk, a compact disc (CD)-ROM, or a digital versatile disc (DVD), or a combination thereof. The memory 930 may not be separately provided but may be included in the processor 920. The memory 930 may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory, and may provide stored data according to a request of the processor 920.

[0331] The processor 920 may control a series of processes so that the BS 900 operates according to an embodiment. For example, the processor 920 may receive a control signal and a data signal through the transceiver 910 and process the received control signal and data signal. The processor 920 may transmit the processed control signal and data signal through the transceiver 910, may write data to and read data from the memory 930, and may perform functions of a protocol stack required by communication standards. To this end, the processor 920 may include at least one processor or microprocessor. A part of the transceiver 910 or the processor 920 may be referred to as a communication processor (CP).

[0332] The processor 920 may include one or more processors such as a central processing unit (CPU), an application processor (AP), a digital signal processor (DSP), a graphics processor such as a graphics processing unit (GPU) or a vision processing unit (VPU), or an AI processor such as a neural processing unit (NPU). For example, when the one or more processors are AI processors, they may be designed as a hardware structure specialized in processing a particular AI model.

[0333] The BS 900 can perform operations of gNB, eNB or base station of Figure 1 to Figure 8.

[0334] Figure 10 illustrates a structure of a UE, according to an embodiment of the disclosure.

[0335] Referring to FIG. 10, the UE 1000 may include a processor 1020, a memory 1030, and a transceiver 1010. However, elements of the UE 1000 are not limited thereto. For example, the UE 1000 may include more or fewer elements than those described above. The processor 1020, the memory 1030, and the transceiver 1010 may be implemented as a single chip.

[0336] The processor 1020 may include one or more processors. In this case, the one or more processors may include a general-purpose processor such as a CPU, an AP, or a DSP, a graphics processor such as a GPU or a VPU, or an AI processor such as an NPU. For example, when the one or more processors are AI processors, they may be designed as a hardware structure specialized in processing a particular AI model.

[0337] The processor 1020 may control a series of processes so that the UE 1000 operates according to an embodiment. For example, the processor 1020 may receive a control signal and a data signal through the transceiver 1010 and process the received control signal and data signal. The processor 1020 may transmit the processed control signal and data signal through the transceiver 1010. Furthermore, the processor 1020 may control input data derived from the received control signal and data signal to be processed according to a predefined operation rule or AI model stored in the memory 1030. The processor 1020 may write data to and read data from the memory 1030, may perform functions of a protocol stack required by communication standards, and may include at least one processor. A part of the transceiver 1010 or the processor 1020 may be referred to as a CP.

[0338] The memory 1030 may store a program and data required to operate the UE 1000, may store control information or data included in a signal obtained by the UE 1000, and may store control information or data included in a signal obtained by the UE800. The memory 1030 may include a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination thereof. The memory 1030 may not be separately provided but may be included in the processor 1020. The memory 1030 may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory and may provide stored data according to a request of the processor 1020.

[0339] The transceiver 1010 may refer to a transmitter and a receiver, and the transceiver 1010 of the UE 1000 may transmit or receive signals to or from a BS or a network entity. The transmitted or received signals may include control information and data. To this end, the transceiver 1010 may include an RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and an RF receiver for low-noise amplifying and down-converting a frequency of a received signal. However, this is merely an example of the transceiver 1010, and elements of the transceiver 1010 are not limited to the RF transmitter and the RF receiver. The transceiver 1010 may receive signals through wireless channels and output the signals to the processor 1020, and may transmit signals output from the processor 1020 through wireless channels.

[0340] The processor 1020 may be configured to perform multicast reception in a radio resource control (RRC) inactive state, on a first cell; in case that cell selection criteria is met, selecting a second cell for the multicast reception; identify whether the selected second cell supports the multicast reception in the RRC inactive state; and perform continuously the multicast reception in the RRC inactive state on the selected second cell based on that the selected second cell supports the multicast reception in the RRC inactive state. The UE 1000 can perform operations of UE of Figure 1 to Figure 8.

[0341] According to an aspect of the present disclosure there is provided a method of operating a User Equipment, operably connected to a terrestrial telecommunication network, for mobility to an Air to Ground, ATG, telecommunication network, comprising the steps of: receiving ATG assistance information for performing measurements of an ATG cell in the ATG telecommunication network; performing measurement of the ATG cell; and performing mobility to the ATG cell.

[0342] In an embodiment of the disclosure, the ATG assistance information is received in broadcasted information from the terrestrial telecommunication network.

[0343] In an embodiment of the disclosure, the ATG assistance information is received in a measurement configuration, transmitted from the terrestrial telecommunication network.

[0344] In an embodiment of the disclosure, the ATG assistance information is received, from the terrestrial telecommunication network, in an RRC release message.

[0345] In an embodiment of the disclosure, the UE performs mobility to the ATG cell based on receiving an RRC release with redirection from the terrestrial network.

[0346] In an embodiment of the disclosure, the UE additionally performs at least one neighbour cell measurement.

[0347] In an embodiment of the disclosure, the UE sends a measurement report based on measuring an ATG cell using the ATG assistance information.

[0348] In an embodiment of the disclosure, the terrestrial network provides ATG assistance information for ATG cells or ATG frequencies, to allow for the UE to synchronize to measure the ATG cells.

[0349] In an embodiment of the disclosure, the ATG assistance information is provided in a broadcast fashion, i.e via System Information. In an embodiment of the disclosure, the ATG assistance information is provided in ATG SIB22.

[0350] In an embodiment of the disclosure, the ATG assistance information can be configured in a dedicated fashion to allow for a UE to synchronize and measure an ATG cell. This can be configured in a measurement configuration, such as MeasObjectNR in MeasConfig, and be configured per cell or per frequency. If it is configured per cell, then there may be a single ATG assistance information element per cell, and if it is configured per frequency, then there may be a list of ATG assistance information elements.

[0351] In an embodiment of the disclosure, a UE that is connected to an E-UTRAN cell may be provided with ATG assistance information. This may be configured in a MeasObjectNR in the E-UTRAN NR inter-RAT measurement configuration

[0352] In an embodiment of the disclosure, the UE can be configured with dedicated ATG assistance information to be used in RRC inactive.

[0353] In an embodiment of the disclosure, the UE performs mobility to the ATG cell based on receiving a handover command from the terrestrial network.

[0354] In an embodiment of the disclosure, the UE reports to a terrestrial network its capabilities to perform mobility from a terrestrial to an ATG network.

[0355] According to an aspect of the present disclosure there is provided apparatus arranged to perform the method of the first aspect.

[0356] Embodiments of the disclosure provide a method for configuring a UE with ATG assistance information in order to perform TN to ATG mobility.

[0357] In an embodiment of the disclosure, a network may re-direct an ATG UE from a terrestrial network to an ATG network.

[0358] At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as 'component', 'module' or 'unit' used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term "comprising" or "comprises" means including the component(s) specified but not to the exclusion of the presence of others.

[0359] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0360] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0361] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0362] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0363] It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should be considered as available for other similar features or aspects in other embodiments. The afore-described embodiments may operate in combination when required. For example, a base station and a UE may operate according to a combination of parts of the embodiments of the disclosure.

Claims

1.A method of operating a User Equipment, operably connected to a terrestrial telecommunication network, for mobility to an Air to Ground (ATG) telecommunication network, comprising the steps of:receiving ATG assistance information for performing measurements of an ATG cell in the ATG telecommunication network;performing measurement of the ATG cell; andperforming mobility to the ATG cell.2.The method of claim 1, wherein the ATG assistance information is received in broadcasted information from the terrestrial telecommunication network.3.The method of claim 1, wherein the ATG assistance information is received in a measurement configuration, transmitted from the terrestrial telecommunication network.4.The method of claim 3, where the ATG assistance information is received, from the terrestrial telecommunication network, in an RRC release message.5.The method of claim 4 wherein the UE performs mobility to the ATG cell based on receiving an RRC release with redirection from the terrestrial network.6.The method in any one of claims 1 to 3 wherein the UE additionally performs at least one neighbour cell measurement.7.The method in any one of claims 1 to 3 or 6 where the UE sends a measurement report based on measuring an ATG cell using the ATG assistance information.8.The method in any one of claims 1 to 3 or 5 to 6 wherein the UE performs mobility to the ATG cell based on receiving a handover command from the terrestrial network.9.A user equipment (UE) operably connected to a terrestrial telecommunication network, for mobility to an air to ground (ATG) telecommunication network, the UE comprising:a transceiver; andat least one processor coupled to the transceiver and configured to:receive ATG assistance information for performing measurements of an ATG cell in the ATG telecommunication network;perform measurement of the ATG cell; andperform mobility to the ATG cell.

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