COMMUNICATION METHOD, USER EQUIPMENT AND NETWORK NODE

Abstract

A communication control method according to one aspect of the present invention is a communication control method for a mobile communication system. The communication control method comprises a step for a user equipment transmitting altitude information regarding the altitude of the user equipment to a network node, either when an RRC connection to the network node is established or after an RRC connection to the network node is established.

Description

Communication Control Method

[0001] The present disclosure relates to a communication control method in a mobile communication system.

[0002] The specifications of the Third Generation Partnership Project (3GPP), a standardization project for mobile communication systems, define an aerial UE (Aerial UE) (see, for example, Non-Patent Document 1 and Non-Patent Document 2). For example, an Aerial UE can report its altitude and its location information including its vertical and horizontal speeds. Through these specifications, 3GPP appropriately supports communication with an Aerial UE flying in the sky.

[0003] 3GPP TS 36.300 V17.1.0 (2022-6)3GPP TS 36.331 V17.1.0 (2022-6)

[0004] A communication control method according to one aspect is a communication control method in a mobile communication system, the communication control method including a step of transmitting altitude information regarding an altitude of the user equipment to a network node (or a network device) when the user equipment establishes an RRC connection with the network node or after the RRC connection with the network node is established.

[0005] According to one aspect, there is provided a communication control method in a mobile communication system, the communication control method including: receiving, by a user equipment, aerial-use cell information regarding an aerial-use cell broadcast from a neighboring cell; and transmitting, by the user equipment, the aerial-use cell information to a serving cell.

[0006] Furthermore, a communication control method according to one aspect is a communication control method in a mobile communication system, the communication control method including a step of transmitting, by a network node, aerial-use cell information relating to an aerial-use cell to an adjacent network node, or receiving, by a network node, the aerial-use cell information from the adjacent network node.

[0007] FIG. 1 is a diagram illustrating an example of the configuration of a mobile communication system according to the first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a UE (user equipment) according to the first embodiment. FIG. 3 is a diagram illustrating an example of the configuration of a gNB (base station) according to the first embodiment. FIG. 4 is a diagram illustrating an example of the configuration of a protocol stack related to a user plane according to the first embodiment. FIG. 5 is a diagram illustrating an example of the configuration of a protocol stack related to a control plane according to the first embodiment. FIG. 6 is a diagram illustrating an example of a cell configuration according to the first embodiment. FIG. 7 is a diagram illustrating an example of an operation according to the first embodiment. FIG. 8 is a diagram illustrating an example of an operation according to the second embodiment. FIG. 9 is a diagram illustrating another example of an operation according to the second embodiment. FIG. 10 is a diagram illustrating an example of an operation according to the third embodiment.

[0008] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0009] [First embodiment]

[0010] (Configuration of mobile communication system) Fig. 1 is a diagram showing the configuration of a mobile communication system according to the first embodiment. The mobile communication system 1 conforms to the 5th Generation System (5GS) of the 3GPP standard. Although the following description will be given using 5GS as an example, the mobile communication system may also be at least partially applied to an LTE (Long Term Evolution) system. The mobile communication system may also be at least partially applied to a 6th Generation (6G) system.

[0011] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. Furthermore, the 5GC 20 may be simply referred to as the core network (CN) 20.

[0012] The UE 100 is a mobile wireless communication device. The UE 100 may be any device that is used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0013] The NG-RAN 10 includes a base station (called a "gNB" in a 5G system) 200. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, and the like. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource for wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0014] In addition, the gNB 200 can also be connected to the EPC (Evolved Packet Core), which is the LTE core network. An LTE base station (eNB: evolved Node B) can also be connected to the 5GC 20. The LTE base station and the gNB 200 can also be connected via an inter-base station interface.

[0015] The 5GC20 includes an Access and Mobility Management Function (AMF) and a User Plane Function (UPF) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and the UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0016] 2 is a diagram illustrating an example of the configuration of a UE 100 (user equipment) according to the first embodiment. The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit that performs wireless communication with the gNB 200.

[0017] The receiving unit 110 performs various reception operations under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

[0018] The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0019] The control unit 130 performs various controls and processes in the UE 100. Such processes include processes of each layer described below. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processes by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. Note that the control unit 130 may perform each process or operation in the UE 100 in each of the embodiments described below.

[0020] 3 is a diagram showing the configuration of a gNB 200 (base station) according to the first embodiment. The gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240. The transmitter 210 and the receiver 220 constitute a wireless communication unit that performs wireless communication with the UE 100. The backhaul communication unit 240 constitutes a network communication unit that communicates with the CN 20.

[0021] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0022] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0023] The control unit 230 performs various controls and processes in the gNB 200. Such processes include processes for each layer described below. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processes by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. Note that the control unit 230 may perform each process or operation in the gNB 200 in each of the embodiments described below.

[0024] The backhaul communication unit 240 is connected to adjacent base stations via an Xn interface, which is an interface between base stations. The backhaul communication unit 240 is connected to the AMF / UPF 300 via an NG interface, which is an interface between a base station and a core network. Note that the gNB 200 is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and the two units may be connected by an F1 interface, which is a fronthaul interface.

[0025] FIG. 4 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0026] The user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0027] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on a physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires the successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from gNB200 has a CRC parity bit scrambled by the RNTI added.

[0028] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100.

[0029] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via a logical channel.

[0030] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0031] The SDAP layer maps IP flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0032] FIG. 5 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

[0033] The protocol stack of the radio interface of the control plane has a Radio Resource Control (RRC) layer and a Non-Access Stratum (NAS) instead of the SDAP layer shown in FIG.

[0034] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0035] The NAS, which is located above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS of the UE 100 and the NAS of the AMF 300. Note that the UE 100 has an application layer and the like in addition to the radio interface protocol. Also, the layer below the NAS is called an Access Stratum (AS).

[0036] (UAV) Here, an unmanned aerial vehicle (UAV: Unmanned Aerial Vehicle or Uncrewed Aerial Vehicle; hereinafter, "unmanned aerial vehicle" may be referred to as "UAV") according to the first embodiment will be described.

[0037] A UAV generally refers to an unmanned aerial vehicle such as a drone. However, in the first embodiment, a UE located at an altitude equal to or greater than a predetermined threshold (or exceeding the predetermined threshold) is referred to as a UAV. A UAV may be a UE capable of wireless communication with a gNB 200 while flying unmanned in the sky, like an unmanned aerial vehicle. Alternatively, a UAV may be provided on an unmanned aerial vehicle. Alternatively, a UAV may be provided on a manned aerial vehicle. For example, when an airplane is flying at an altitude equal to or greater than a predetermined threshold, a UE owned by a user on board the airplane may also be a UAV. A UAV may be a UAV UE. Alternatively, a UAV may be an aerial UE (aerial UE). A UAV may be used to distinguish it from a UE used on the ground. However, when there is no particular distinction between the UE and the UAV, a UAV may be included in the UE as an example of a UE. In this case, a UAV and a UE may be collectively referred to as a UE. The configuration example of UE 100 shown in Figure 2 may represent a configuration example of a UAV.

[0038] In 3GPP, the following specifications are provided as functions to support an aerial UE:

[0039] First, the flying UE can report its altitude. For example, the flying UE can report its altitude when its altitude is above or below a threshold. At this time, the flying UE can also report its location information. The location information can include the horizontal and vertical speed of the flying UE.

[0040] Second, the LTE system network (E-UTRAN) can request the flying UE to report flight route information. The flight route information represents waypoints (passing point information or point information) on the route of the flying UE. The flight route information may include multiple waypoints. The waypoints are represented as three-dimensional position information. The flying UE may report time information (timestamp) for each waypoint by including it in the flight route information.

[0041] Third, whether or not a flying UE is supported (or whether or not it can be used as a flying UE) is included in the subscription information for each user. The HSS (Home Subscriber Server) in the LTE system stores subscriber information for each user. Whether or not a flying UE is supported is included in the subscription information. The subscription information is transmitted from the HSS to the eNB, which is a base station in the LTE system, under the control of the MME (Mobility Management Entity). The eNB can determine whether or not to communicate wirelessly with the flying UE.

[0042] Fourth, the event H1 and the event H2 can be used as trigger conditions for a measurement report. The event H1 represents an event condition when the altitude of the flying UE exceeds a threshold. Meanwhile, the event H2 represents an event condition when the altitude of the flying UE falls below the threshold. These event conditions are determined to be satisfied using a hysteresis value, an offset value, and a threshold value in addition to the altitude.

[0043] The 3GPP specifications are based on the assumption that flying UEs (i.e., UAVs) will be used in the LTE system.

[0044] Meanwhile, 3GPP has begun discussions on introducing UAVs into NR (New Radio). Regarding UAVs, 3GPP has agreed to use the above-mentioned events H1 and H2, to report the altitude, position, and speed of the UAV, and to report the flight path plan.

[0045] (Terrestrial Cells and Aerial Cells) For example, assume that terrestrial cells and aerial cells coexist within a network. Fig. 6 is a diagram showing an example of a cell configuration in such a case.

[0046] As shown in Figure 6, the mobile communication system 1 includes a ground cell and an air cell. In the example shown in Figure 6, a ground cell is formed by gNB200-T1 and gNB200-T2, and an air cell is formed by gNB200-U. In Figure 6, in the ground cell, UE100-1 to 100-4 perform wireless communication with gNB200-T1 and 200-T2, and in the air cell, UAV150-1 and 150-2 perform wireless communication with gNB200-U.

[0047] Here, in order for the UEs 100-1 to 100-4 to perform appropriate wireless communication in the ground cell and for the UAVs 150-1 and 150-2 to perform appropriate wireless communication in the air cell, the following two scenarios are assumed.

[0048] In the first scenario, a dedicated frequency is assigned to the air cell, and different frequencies are used for the ground cell and the air cell. In the first scenario, for example, wireless communication by UAVs 150-1 and 150-2 and wireless communication by UEs 100-1 to 100-4 are performed using different frequencies, so that interference between the two wireless communications can be avoided.

[0049] On the other hand, the second scenario is a scenario in which the same frequency (or the same frequency range) is used in the terrestrial cell and the aerial cell. In the second scenario, since the terrestrial cell and the aerial cell share the same frequency, there is no need to increase frequency resources. Therefore, in the second scenario, frequency resources can be used more effectively.

[0050] (Communication Control Method According to First Embodiment) In the first embodiment, attention is focused on the second scenario. A problem that arises when applying the second scenario to the mobile communication system 1 is interference. For example, when UAVs 150-1 and 150-2 (hereinafter, when UAVs 150-1 and 150-2 are not distinguished from each other, they may be referred to as UAVs 150) perform uplink communication, there are cases in which wireless signals reach not only the serving cell and its adjacent cells but also a wider area. In such a case, if UAV 150 and UE 100 on the ground use the same frequency, signals from UAV 150 may cause interference. A problem specific to UAVs is that wireless communication by UAV 150 is more susceptible to interference than wireless communication by UE 100 on the ground.

[0051] Therefore, in order to avoid interference in the second scenario, the mobile communication system 1 needs to quickly make appropriate settings for the UAV 150 flying in the sky.

[0052] However, in the mobile communication system 1, there is a problem of how to identify the UAV 150 flying in the sky in order to quickly perform appropriate settings.

[0053] In an LTE system, an information element (Aerial UE subscription information) indicating whether a UE is authorized to function as an aerial UE can be sent from the HSS to the MME using an S6a message. The information element can then be sent from the MME to the eNB using an S1AP message. Thus, in an LTE system, the eNB can determine whether a UE is authorized to function as an aerial UE (or is capable of being an aerial UE).

[0054] However, the eNB cannot determine whether the UE is actually flying. Therefore, the eNB may not be able to identify that the UE is a UAV. In NR, there is currently no provision in 3GPP for the gNB 200 to determine whether the UE 100 is a UAV 150. Therefore, the gNB 200 may not be able to identify whether the UE 100 is a UAV 150.

[0055] Therefore, in the first embodiment, an object is to enable the UE 100 to appropriately identify that it is the UAV 150. Specifically, in the first embodiment, an object is to enable the gNB 200 to determine whether the UE 100 is flying at a certain altitude.

[0056] Therefore, in the first embodiment, when a user equipment (e.g., UE100) establishes an RRC connection with a base station (e.g., gNB200), or after the RRC connection is established with the base station, altitude information regarding the altitude of the user equipment is transmitted to the base station. As a result, when the gNB200 determines that the UE100 is flying at an altitude exceeding a predetermined threshold based on the altitude information of the UE100, it can identify that the UE100 is flying in the sky, that is, that the UE100 is a UAV150. By appropriately identifying that the UE100 is a UAV150, the gNB200 can quickly perform appropriate processing for the UAV150, making it possible to avoid interference problems in the second scenario.

[0057] (Example of Operation According to First Embodiment) FIG. 7 is a diagram showing an example of operation according to the first embodiment.

[0058] As shown in Figure 7, in step S10, UE100 transmits altitude information regarding its own altitude to gNB200.

[0059] First, there are, for example, the following methods for transmitting altitude information. That is, UE100 in an RRC idle state or an RRC inactive state may transmit a message (Msg1) including altitude information to gNB200 using a random access resource (or a PRACH (Physical Random Access Channel) resource) dedicated to UAVs (unmanned aerial devices). The random access resource dedicated to UAVs may be set in advance by gNB200. Alternatively, the UE may transmit Msg3 (RRC Setup Request (RRCSetupRequest) message) including altitude information instead of Msg1. The UE may also transmit Msg5 (RRC Setup Complete (RRCSetupComplete) message) including altitude information. Alternatively, UE100 in the RRC connected state may transmit UE-assisted information (UAI) including altitude information to gNB200. In this way, UE100 may transmit altitude information when establishing an RRC connection with gNB200. UE100 may transmit altitude information after RRC connection establishment. However, it is preferable that UE100 transmits altitude information as soon as possible after RRC connection establishment.

[0060] Second, the altitude information may include, for example, the following information. That is, the altitude information may include information indicating that the UE 100 has flight capability. Alternatively, the altitude information may include information regarding the current or past altitude of the UE 100. The information regarding the past altitude may include time information (or a timestamp). Alternatively, the altitude information may include information representing the altitude of the UE 100 using regions divided according to altitude (this information may be referred to as "region information"). The region information may be composed of, for example, three region information items: high altitude, low altitude, and terrestrial, depending on the altitude. In this way, the altitude information may include region information according to the altitude of the UE 100 itself. The altitude information may be represented by an altitude acquired by an altitude sensor (or a distance sensor such as radar or lidar) provided in the UE 100. The altitude itself may be represented by sea level. The altitude itself may be represented by altitude above sea level. The altitude itself may be expressed as height above ground level.

[0061] Thirdly, the trigger for UE100 to transmit altitude information is, for example, as follows. That is, UE100 may transmit altitude information when the current altitude is equal to or greater than the first threshold (or when the current altitude becomes higher than the first threshold). The first threshold may be included in the SIB and broadcast from gNB200.

[0062] In step S11, gNB200 performs predetermined processing in response to receiving altitude information.

[0063] First, as a predetermined process, the gNB 200 may perform a UAV-dedicated measurement configuration for the UE 100 (i.e., the UAV 150). The UAV-dedicated measurement configuration enables the UAV 150 to set a trigger condition (e.g., H1 or H2) for transmitting a measurement report, and to set UAV-specific information (such as location information including altitude information) to be included in the measurement report. Note that the gNB 200 may perform this configuration by transmitting an RRC message (an RRCReconfiguration message or an RRCResume message) including a UAV-dedicated measurement configuration to the UAV 150.

[0064] Second, as a predetermined process, the gNB 200 may hand over the UE 100 to an appropriate frequency. For example, even in the second scenario, it is possible to separate frequencies dedicated to UAVs and frequencies dedicated to ground UEs within the range of shared frequencies. When the gNB 200 determines that the UE 100 is a UAV 150, it may hand over the UAV 150 to an airborne cell that uses a frequency dedicated to UAVs. Specifically, to enable the UAV 150 to easily hand over to the cell, a measurement configuration may be set for the UAV 150 in which the threshold used in the event condition is lower than in a certain case.

[0065] Second Embodiment Next, a second embodiment will be described, focusing on the differences from the first embodiment.

[0066] The second embodiment is an example in which a UE 100 in an RRC connected state with a serving cell 200-1 acquires aerial cell information regarding aerial cell from a neighboring cell (or neighboring gNB) 200-2, and transmits the acquired aerial cell information to the serving cell 200-1.

[0067] Specifically, first, the user equipment (e.g., UE 100) receives aerial cell information regarding the aerial cell broadcast from a neighboring cell (e.g., neighboring cell 200-2). Second, the user equipment transmits the aerial cell information to a serving cell (e.g., serving cell 200-1).

[0068] As a result, for example, gNB200-1 (or serving cell) can grasp the aerial cell information used in adjacent gNB200-2 (or adjacent cell). And, gNB200-1 can also perform interference avoidance processing for UAV150 based on the aerial cell information. Therefore, gNB200-1 can take measures to solve the interference problem in the second scenario.

[0069] (Example of Operation According to Second Embodiment) FIG. 8 is a diagram showing an example of operation according to the second embodiment.

[0070] As shown in FIG. 8, in step S20, UE100 is in an RRC connected state with serving cell 200-1 (or gNB200-1).

[0071] In step S21, the neighboring cell (or neighboring gNB) 200-2 adjacent to the serving cell 200-1 broadcasts an SIB (System Information Block) including aerial cell information related to the aerial cell. The aerial cell information may include the cell ID of the aerial cell. Alternatively, the aerial cell information may include information on the frequency (or aerial frequency) used in the aerial cell. Alternatively, the aerial cell information may be expressed in the form of a list of cell IDs and / or the frequencies. The neighboring cell may broadcast cell list information representing a cell list managed by the neighboring cell. An identifier indicating that the cell is an aerial cell may be assigned to each entry in the cell list in the cell list information. The cell list entry to which an identifier indicating that the cell is an aerial cell is assigned may be the aerial cell information. That is, the neighboring cell 200-2 may broadcast cell list information including the aerial cell information.

[0072] In step S22, the UE 100 identifies the airspace cell in response to receiving the SIB broadcast in step S21. For example, the UE 100 may store the cell ID of the airspace cell in a memory or the like, and identify the airspace cell by comparing the cell ID with the cell ID included in the airspace cell information received from the neighboring cell 200-2.

[0073] In step S23, the UE 100 transmits the airspace cell information received from the neighboring cell 200-2 to the serving cell 200-1. When the UE 100's altitude is higher than the second threshold (or when the UE 100's altitude becomes equal to or greater than the second threshold), the UE 100 may transmit the airspace cell information to the serving cell 200-1. This enables the serving cell 200-1 to identify that the UE 100 is a UAV 150 flying in the airspace. The UE 100 may transmit an RRC message including the airspace cell information to the serving cell 200-1. Note that the second threshold and the first threshold (the threshold for determining whether to transmit altitude information) described in the first embodiment may be the same threshold or different thresholds. The second threshold may be included in an SIB and broadcast from the serving cell 200-1, for example.

[0074] In step S24, the serving cell may perform a predetermined process when the frequency used in the serving cell is different from the airspace frequency included in the airspace cell information received from the UE 100. The predetermined process includes, for example, the following three processes.

[0075] First, as a predetermined process, the serving cell 200-1 performs transmission power control for the UE 100. For example, when the serving cell 200-1 identifies that the UE 100 is the UAV 150, the serving cell 200-1 may use a transmission power control (TPC) command to control the UAV 150 to suppress its transmission power. This makes it possible to avoid interference caused by radio signals transmitted from the UAV 150.

[0076] Second, as a predetermined process, the serving cell 200-1 may hand over the UE 100 to an appropriate frequency, as in the first embodiment. For example, when the serving cell 200-1 identifies that the UE 100 is the UAV 150, the serving cell 200-1 may control the UAV 150 to hand over to an airspace cell that supports an airspace frequency.

[0077] Third, as a predetermined process, the serving cell 200-1 may release the UE 100 in the RRC connected state to an RRC idle state or an RRC inactive state. The serving cell 200-1 may release the UE 100 to the RRC idle state by transmitting an RRC release (RRCRelease) message to the UE 100 in the RRC connected state. Furthermore, the serving cell 200-1 may release the UE 100 to the RRC inactive state by transmitting an RRC release (RRCRelease) message including a suspend configuration (suspendconfig) to the UE 100 in the RRC connected state.

[0078] Another Example of the Second Embodiment Next, another example of the second embodiment will be described.

[0079] In the second embodiment, an example has been described in which the airspace cell information regarding the airspace cell is transmitted from the neighboring cell 200-2 to the serving cell 200-1 via the UE 100. However, this is not limiting. For example, the gNB 200-1 and the neighboring gNB 200-2 can share the airspace cell information by transmitting the information directly to each other without going through the UE 100.

[0080] Specifically, a base station (e.g., gNB200-1) either transmits aerial cell information regarding the aerial cell to a neighboring base station (e.g., neighboring gNB200-2), or receives aerial cell information from a neighboring base station.

[0081] As a result, for example, the neighboring gNB 200-2 can grasp the aerial cell information (for example, the cell ID or the aerial cell frequency used in the aerial cell) used in the gNB 200-1. Then, the neighboring gNB 200-2 can also prepare for interference avoidance processing for the UAV 150 based on the aerial cell information. Therefore, the neighboring gNB 200-2 can take measures to solve the interference problem in the second scenario.

[0082] FIG. 9 is a diagram illustrating another example of operation according to the second embodiment.

[0083] As shown in FIG. 9 , in step S30, the gNB 200-1 transmits aerial cell information to the neighboring gNB 200-2 either when establishing an Xn connection with the neighboring gNB 200-2 or when making a setting change to the neighboring gNB 200-2. The aerial cell information may be the same as that in the second embodiment. The gNB 200-1 may transmit cell list information including the aerial cell information. Regarding the transmission of the aerial cell information, the gNB 200-1 may transmit an Xn connection establishment request (XN SETUP REQUEST) message including the aerial cell information to the neighboring gNB 200-2. Alternatively, the gNB 200-1 may transmit an NG-RAN setting update (NG-RAN NODE CONFIGURATION UPDATE) message including the aerial cell information to the neighboring gNB 200-2.

[0084] In step S31, gNB200-1 detects the connection of UAV150. UAV150 enters an RRC connected state with gNB200-1.

[0085] In step S32, the gNB 200-1 may perform a predetermined process. The predetermined process may be transmission power control in a suppression direction for the UAV 150, as in the second embodiment. Alternatively, the predetermined process may be handing over the UAV 150 to an airspace cell (or an airspace frequency), as in the second embodiment. Alternatively, the predetermined process may be releasing the UAV 150 in the RRC connected state to an RRC idle state or an RRC inactive state, as in the second embodiment.

[0086] In another operation example of the second embodiment, an example in which the gNB 200-1 transmits the aerial cell information to the adjacent gNB 200-2 has been described, but the present invention is not limited to this. For example, the adjacent gNB 200-2 may transmit the aerial cell information related to the aerial cell that it manages to the gNB 200-1. Whether the gNB 200-1 transmits the aerial cell information or the adjacent gNB 200-2 transmits the aerial cell information, the aerial cell information can be shared between the gNB 200-1 and the adjacent gNB 200-2.

[0087] Third Embodiment Next, a third embodiment will be described.

[0088] In the third embodiment, an example is described in which UE 100 (i.e., UAV 150) located at an altitude above a predetermined threshold transmits a PRACH preamble using a random access resource dedicated to the UAV (or a random access resource for the sky).

[0089] As described in the first embodiment, a problem specific to UAVs is that wireless communication by the UAV 150 is more susceptible to interference than wireless communication by the ground UE 100. In future discussions in 3GPP, it is expected that various interference avoidance measures will be taken for the UAV 150 in the RRC connected state.

[0090] On the other hand, if interference occurs when UAV 150 performs a random access procedure, there is currently no workaround.

[0091] Therefore, the third embodiment aims to avoid interference in the random access procedure. Specifically, the third embodiment aims to avoid collision of PRACH preamble transmissions.

[0092] Therefore, in the third embodiment, first, a base station (e.g., gNB 200) sets a random access resource dedicated to the unmanned aerial vehicle (UAV) to a user equipment (e.g., UE 100). Second, a user equipment located at an altitude equal to or higher than a predetermined threshold transmits a PRACH preamble to the base station using a random access resource dedicated to the unmanned aerial vehicle (UAV).

[0093] Thus, in the third embodiment, the UE 100 (or the UAV 150) transmits the PRACH preamble to the gNB 200 using a random access resource dedicated to the UAV, thereby avoiding collision with the PRACH preamble transmitted using other resources. Therefore, in the third embodiment, interference in the random access procedure can be avoided.

[0094] The two embodiments differ in that the main purpose of the third embodiment is to avoid interference, while the main purpose of the first embodiment is for the gNB 200 to determine whether the UE 100 is located at an altitude equal to or greater than the first threshold. However, even in the first embodiment, the gNB 200 that has determined that the gNB 200 is a UAV 150 can set an interference avoidance measure for the UAV 150. Therefore, the two embodiments can be said to have in common the purpose of interference avoidance.

[0095] In the first embodiment, we described transmitting a message (Msg1) containing altitude information using random access resources dedicated to UAVs, but such transmission becomes possible by setting random access resources dedicated to UAVs by gNB200.

[0096] In addition, 3GPP Rel-17 introduced a common framework for PRACH Partitioning, which enables PRACH resource configuration for each function, such as RedCap (Radio Reduced Capability), SDT (Small Data Transmission), or RAN Slicing.

[0097] (Operation Example According to Third Embodiment) FIG. 10 is a diagram showing an operation example according to the third embodiment.

[0098] As shown in FIG. 10, in step S40, gNB200 configures UE100 with a PRACH resource dedicated to UAV.

[0099] First, a PRACH resource dedicated to a UAV may be configured. For example, a PRACH resource dedicated to a UAV may be added to the PRACH resource for the ground UE 100. Alternatively, a new information element (e.g., "Aerial vehicles") indicating that the resource is dedicated to a UAV may be added to an information element (FeatureCombination) indicating a function or a set of functions related to random access resources. Information regarding the PRACH resource dedicated to a UAV may be configured by an information element (RACH-ConfigCommon) indicating the PRACH resource.

[0100] Second, a PRACH resource dedicated to a UAV may be configured for each altitude. For example, a PRACH resource #1 dedicated to a UAV may be configured for a first range of altitudes, and a PRACH resource #2 dedicated to a UAV may be configured for a second range of altitudes. An information element (FeatureCombination) representing a function or a set of functions related to random access resources may include an information element (e.g., "Aerial vehicles list") shown in list format for each altitude. In this case, multiple information elements (RACH-ConfigCommon) representing PRACH resources may be configured for each altitude.

[0101] The PRACH resource may be indicated by a RACH common setting, a preamble number, and / or a radio resource number. The preamble number may be indicated as a range of preamble numbers available as PRACH resources (e.g., a start number and an end number). The radio resource number may also be indicated as a range of preamble numbers available as PRACH resources (e.g., a start number and an end number). The radio resource itself may be represented by frequency and / or time.

[0102] In step S41, UE 100 selects a PRACH resource according to its own altitude and transmits a PRACH preamble using the selected PRACH resource. When UE 100 determines that it is located at an altitude below a predetermined threshold (or equal to or less than the predetermined threshold) (i.e., located on the ground), UE 100 may transmit the PRACH preamble using a normal PRACH resource used as a terrestrial UE. Also, for example, when UE 100 determines that it is located at an altitude equal to or greater than the predetermined threshold (or exceeds the predetermined threshold), UE 100 may transmit the PRACH preamble using a PRACH resource dedicated to any UAV depending on the altitude.

[0103] The predetermined threshold value may be the same as the first threshold value described in the first embodiment, or may be the same as the second threshold value described in the second embodiment.

[0104] [Other Embodiments] The above-described operational flows are not limited to being implemented independently, but can be implemented by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow. In each flow, it is not necessary to execute all steps, and only some steps may be executed.

[0105] In the above-described embodiments and examples, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB) or a 6G base station. The base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU of the IAB node. The UE 100 may also be an MT (Mobile Termination) of the IAB node.

[0106] Also, the term "network node" primarily refers to a base station, but may also refer to a device in the core network or part of a base station (CU, DU, or RU).

[0107] A program may be provided that causes a computer to execute each process performed by the UE 100 or the gNB 200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by the UE 100 or the gNB 200 may be integrated, and at least a portion of the UE 100 or the gNB 200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0108] As used in this disclosure, the terms "based on" and "depending on" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "depending only on" and "depending at least in part on." Furthermore, the terms "include" and "comprise" do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Furthermore, the term "or" as used in this disclosure is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0109] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes can be made within the scope of the gist. Furthermore, it is also possible to combine all or part of each embodiment, each operation, each process, and each step within the scope of consistent combinations.

[0110] This application claims priority to U.S. Provisional Application No. 63 / 409,868 (filed September 26, 2022), the entire contents of which are incorporated herein by reference.

[0111] (Supplementary Note) (Supplementary Note 1) A communication control method in a mobile communication system, comprising a step of a user equipment transmitting altitude information regarding the altitude of the user equipment to the network node either when establishing an RRC connection with the network node or after the RRC connection with the network node has been established.

[0112] (Supplementary Note 2) The communication control method according to Supplementary Note 1, wherein the transmitting step includes a step in which the user equipment transmits a message including the altitude information to the network node using a random access resource dedicated to an unmanned aerial vehicle (UAV).

[0113] (Supplementary Note 3) The communication control method according to any one of Supplementary Note 1 and Supplementary Note 2, wherein the altitude information includes information indicating that the user device has flight capability.

[0114] (Supplementary Note 4) The communication control method according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the altitude information includes information about a current or past altitude of the user device.

[0115] (Supplementary Note 5) The communication control method according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the altitude information includes information representing the altitude of the user device using areas divided according to the altitude.

[0116] (Supplementary Note 6) The communication control method according to any one of Supplementary Note 1 to Supplementary Note 5, wherein the transmitting step includes a step of the user device transmitting the altitude information when an altitude of the user device is equal to or greater than a first threshold.

[0117] (Supplementary Note 7) A communication control method in a mobile communication system, comprising: a step of receiving, by a user equipment, aerial use cell information regarding an aerial use cell broadcast from a neighboring cell; and a step of transmitting, by the user equipment, the aerial use cell information to a serving cell.

[0118] (Supplementary Note 8) The communication control method according to Supplementary Note 7, wherein the transmitting step includes a step of the user equipment transmitting the sky cell information when an altitude of the user equipment is higher than a second threshold.

[0119] (Supplementary Note 9) A communication control method in a mobile communication system, comprising: a step in which a network node performs one of transmitting aerial-use cell information relating to aerial-use cell to an adjacent network node, and receiving the aerial-use cell information from the adjacent network node.

[0120] (Supplementary Note 10) The communication control method according to Supplementary Note 9, wherein the transmitting step includes a step of transmitting the aerial cell information to the adjacent network node when the network node establishes a connection with the adjacent network node or when a setting change is made to the adjacent network node.

[0121] (Supplementary Note 11) The communication control method according to any one of Supplementary Note 7 to Supplementary Note 10, wherein the aerial cell information includes a cell ID of the aerial cell or a frequency used in the aerial cell.

[0122] (Supplementary Note 12) A communication control method in a mobile communication system, comprising: a step in which a network node sets random access resources dedicated to an unmanned aerial vehicle (UAV) to a user equipment; and a step in which the user equipment, located at an altitude equal to or higher than a predetermined threshold, transmits a PRACH preamble to the network node using the random access resources dedicated to the unmanned aerial vehicle (UAV).

[0123] (Supplementary Note 13) The communication control method according to Supplementary Note 12, wherein the random access resource dedicated to the unmanned aerial vehicle (UAV) is a resource that differs depending on the altitude of the user device.

Claims

1. A communication control method in a mobile communication system, comprising: transmitting altitude information relating to an altitude of the user equipment to the network node either when establishing an RRC connection to the network node or after the RRC connection to the network node is established. Communications control method.

2. The transmitting step includes the user equipment transmitting a message including the altitude information to the network node using a random access resource dedicated to an unmanned aerial vehicle (UAV). The communication control method according to claim 1.

3. The altitude information includes information indicating that the user device has flight capability. The communication control method according to claim 1.

4. The altitude information includes information regarding the current or past altitude of the user device. The communication control method according to claim 1.

5. The altitude information includes information representing the altitude of the user device using areas divided according to altitude. The communication control method according to claim 1.

6. The transmitting includes transmitting the altitude information when an altitude of the user device is equal to or greater than a first threshold. The communication control method according to claim 1.

7. A communication control method in a mobile communication system, comprising: receiving, by a user equipment, aerial use cell information regarding an aerial use cell broadcast from a neighboring cell; The user equipment transmits the airspace cell information to a serving cell. Communications control method.

8. The transmitting step includes transmitting the sky cell information when an altitude of the user equipment is higher than a second threshold. The communication control method according to claim 7.

9. A communication control method in a mobile communication system, comprising: a network node transmitting aerial-use cell information relating to an aerial-use cell to a neighboring network node; and receiving the aerial-use cell information from the neighboring network node. Communications control method.

10. The transmitting step includes transmitting the airspace cell information to the neighboring network node when the network node establishes a connection with the neighboring network node or when the network node makes a setting change to the neighboring network node. The communication control method according to claim 9.

11. The sky-use cell information includes a cell ID of the sky-use cell or a frequency used in the sky-use cell. The communication control method according to claim 7 or 9.

12. A communication control method in a mobile communication system, comprising: A network node configures a user device with a random access resource dedicated to an unmanned aerial vehicle (UAV); The user equipment, located at an altitude equal to or higher than a predetermined threshold, transmits a PRACH preamble to the network node using a random access resource dedicated to the unmanned aerial vehicle (UAV). Communications control method.

13. The random access resource dedicated to the unmanned aerial vehicle (UAV) is a resource that varies depending on the altitude of the user device. The communication control method according to claim 12.

14. A user equipment in a mobile communication system, comprising: a transmitter configured to transmit altitude information regarding an altitude of the user equipment to the network node either when establishing an RRC connection to the network node or after the RRC connection to the network node is established; User equipment.

15. A user equipment in a mobile communication system, comprising: a receiving unit for receiving sky-use cell information regarding the sky-use cell broadcast from an adjacent cell; a transmitter for transmitting the sky cell information to a serving cell. User equipment.

16. A user equipment in a mobile communication system, comprising: A control unit for identifying resources for random access dedicated to an unmanned aerial vehicle (UAV), configured by a network node; A transmitter that transmits a PRACH preamble to the network node using a random access resource dedicated to the unmanned aerial vehicle (UAV) when the UAV is located at an altitude equal to or higher than a predetermined threshold. User equipment.

17. A network node in a mobile communication system, comprising: a transmitter for transmitting airspace-use cell information regarding the airspace-use cell to an adjacent network node; a receiving unit for receiving the sky cell information from the neighboring network node; Network node.

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