Communication methods, user devices, and network nodes

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

Technical Field

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

Background Art

[0002] In the specifications of 3GPP (The Third Generation Partnership Project), which is a standardization project for mobile communication systems, Aerial UE (Aerial User Equipment) is defined (for example, Non-Patent Document 1 and Non-Patent Document 2). For example, an Aerial UE can report its altitude or report position information including vertical and horizontal speeds. Through such specifications, 3GPP appropriately supports communication with Aerial UEs flying in the sky.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

[0004] A communication control method according to one aspect is a communication control method in a mobile communication system. The communication control method includes a step in which a user device transmits altitude information regarding the altitude of the user device to a network node either when establishing an RRC connection with the network node (or network device) or after the RRC connection with the network node is established.

[0005] Furthermore, one embodiment of the communication control method is a communication control method in a mobile communication system. The communication control method includes the steps of: a user device receiving airborne cell information relating to an airborne cell reported from an adjacent cell; and the user device transmitting the airborne cell information to a serving cell.

[0006] Furthermore, one embodiment of the communication control method is a communication control method in a mobile communication system. The communication control method includes the step of a network node either transmitting aerial cell information relating to an aerial cell to an adjacent network node, or receiving aerial cell information from an adjacent network node. [Brief explanation of the drawing]

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

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

[0009] [First Embodiment]

[0010] (Configuration of mobile communication systems) Figure 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. In the following explanation, 5GS will be used as an example, but the mobile communication system may also have at least a portion of the LTE (Long Term Evolution) system applied to it. The mobile communication system may also have at least a portion of the 6th Generation (6G) system applied to it.

[0011] The mobile communication system 1 comprises User Equipment (UE) 100, a 5G radio access network (NG-RAN) 10, and a 5G core network (5GC) 20. Hereafter, NG-RAN 10 may be simply referred to as RAN 10, and 5GC 20 may be simply referred to as core network (CN) 20.

[0012] UE100 is a mobile wireless communication device. UE100 can be any device used by a user. For example, UE100 can be a mobile phone terminal (including smartphones) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or chipset), a sensor or device attached to a sensor, a vehicle or device attached to a vehicle (Vehicle UE), or an aircraft or device attached to an aircraft (Aerial UE).

[0013] NG-RAN10 includes base stations (referred to as "gNBs" in 5G systems) 200. The gNBs 200 are interconnected via the Xn interface, which is an inter-base station interface. Each gNB 200 manages one or more cells. The gNB 200 performs wireless communication with UEs 100 that have established a connection with its own cell. The gNB 200 has radio resource management (RRM) functions, user data routing functions (hereinafter simply referred to as "data"), measurement and control functions for mobility control and scheduling, etc. "Cell" is used as a term to indicate the smallest unit of a wireless communication area. "Cell" is also used as a term to indicate a function or resource that performs wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0014] Furthermore, the gNB200 can also connect to the EPC (Evolved Packet Core), which is the core network of LTE. LTE base stations (eNB: evolved Node B) can also connect to the 5GC20. LTE base stations and the gNB200 can also be connected via an inter-base station interface.

[0015] The 5GC20 includes the AMF (Access and Mobility Management Function) and the UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE100. The AMF manages the mobility of the UE100 by communicating with it using NAS (Non-Access Stratum) signaling. The UPF controls data transfer. The AMF and UPF are connected to the gNB200 via the NG interface, which is the base station-core network interface.

[0016] Figure 2 shows an example configuration of UE100 (user device) according to the first embodiment. UE100 comprises 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 gNB200.

[0017] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it 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 the 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 the processes of each layer described later. 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 for the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of the baseband signal, etc. The CPU executes the programs stored in the memory to perform various processes. Note that the control unit 130 may perform each process or each operation in the UE 100 in each of the embodiments shown below.

[0020] FIG. 3 is a diagram showing the configuration of the gNB 200 (base station) according to the first embodiment. The gNB 200 includes a transmitting unit 2, a receiving unit 220, a control unit 230, and a backhaul communication unit 240. The transmitting unit 210 and the receiving unit 220 constitute a radio communication unit that performs radio 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 the 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 the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 230.

[0023] The control unit 230 performs various control and processing in the gNB200. Such processing includes processing in each layer described later. 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 for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, decoding, etc., of the baseband signal. The CPU executes programs stored in memory and performs various processing. In each of the embodiments shown below, the control unit 230 may perform each processing or operation in the gNB200.

[0024] The backhaul communication unit 240 is connected to an adjacent base station via the Xn interface, which is an inter-base station interface. The backhaul communication unit 240 is connected to the AMF / UPF300 via the NG interface, which is an inter-base station-core network interface. The gNB200 may consist of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally separated), and the two units may be connected by the F1 interface, which is a fronthaul interface.

[0025] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0026] The user plane radio interface protocol consists of a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) 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 UE100's PHY layer and the gNB200's PHY layer via a physical channel. The UE100's PHY layer receives downlink control information (DCI) transmitted from the gNB200 over the physical downlink control channel (PDCCH). Specifically, the UE100 performs blind decoding of the PDCCH using a Radio Network Temporary Identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to its own UE. The DCI transmitted from the gNB200 has a CRC parity bit added, which is scrambled by the RNTI.

[0028] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat request (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of the UE100 and the MAC layer of the gNB200 via the transport channel. The MAC layer of the gNB200 includes a scheduler. The scheduler determines the transport format for the up and down links (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE100.

[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 UE100's RLC layer and the gNB200's RLC layer via a logical channel.

[0030] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

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

[0032] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0033] The control plane's wireless interface protocol stack includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer, instead of the SDAP layer shown in Figure 4.

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

[0035] The NAS, located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the UE100's NAS and the AMF300's NAS. The UE100 also has application layers in addition to the wireless interface protocol. Layers below the NAS are called AS (Access Stratum).

[0036] (UAV) Here, we will describe the 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.

[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 above (or exceeding) a predetermined threshold is called a UAV. A UAV may be a UE capable of wireless communication with the gNB200 while flying unmanned in the air like an unmanned aerial vehicle. Alternatively, a UAV may be installed on an unmanned aerial vehicle. Alternatively, a UAV may be installed on a manned aircraft. For example, a UE owned by a user on board an aircraft while the aircraft is flying at an altitude above a predetermined threshold may also be a UAV. A UAV may be a UAV UE. Alternatively, a UAV may be an aerial UE. A UAV may be used to distinguish it from a UE used on the ground. However, if no particular distinction is made, a UAV may be included in UE as an example of a UE. In this case, UAVs and UEs may be collectively referred to as UEs. The example configuration of UE100 shown in Figure 2 may represent an example configuration of a UAV.

[0038] 3GPP has established the following provisions to support aerial UE (Aircraft Unification) functionality:

[0039] Firstly, a flying UE can report its altitude. For example, a flying UE can report its altitude when it is above or below a certain threshold. At this time, the flying UE can also report its position information. This position information may include the horizontal and vertical velocity of the flying UE.

[0040] Secondly, the LTE system network (E-UTRAN) can request the flight UE to report flight path information. Flight path information represents waypoints (how-through point information or point information) along the flight UE's route. The flight path information may include a large number of waypoints. Waypoints are represented as three-dimensional positional information. The flight UE may report time information (timestamps) for each waypoint in the flight path information.

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

[0042] Fourth, Event H1 and Event H2 can be used as trigger conditions for the measurement report. Event H1 represents the event condition when the altitude of the flying UE exceeds a threshold. On the other hand, Event H2 represents the event condition when the altitude of the flying UE falls below a threshold. Whether or not these event conditions are met is determined using altitude, hysteresis value, offset value, and threshold.

[0043] The 3GPP regulations in this way assume that flight UEs (i.e., UAVs) will be used with LTE systems.

[0044] Meanwhile, 3GPP has begun discussions on introducing UAVs into NR (New Radio). Regarding UAVs, 3GPP has agreed on the use of the aforementioned Event H1 and Event H2, reporting of the UAV's altitude, position, and speed, and reporting of its flight path plan.

[0045] (Ground cells and aerial cells) For example, let's consider a case where ground-based cells and aerial cells coexist within the network. Figure 6 shows an example of a cell configuration illustrating this 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, the ground cells are formed by gNB200-T1 and gNB200-T2, and the air cell is formed by gNB200-U. In Figure 6, in the ground cell, UE100-1 to 100-4 communicate wirelessly with gNB200-T1 and 200-T2, and in the air cell, UAV150-1 and 150-2 communicate wirelessly with gNB200-U.

[0047] Here, in order for UE100-1 to 100-4 to properly conduct radio communication in ground cells and UAV150-1 and 150-2 to properly conduct radio communication in air cells, the following two scenarios are assumed.

[0048] The first scenario involves allocating a dedicated frequency to the airborne cell, with different frequencies being used for the ground cell and the airborne cell. In the first scenario, for example, radio communication by UAV150-1 and 150-2 and radio communication by UE100-1 to 100-4 are conducted on different frequencies, thus making it possible to avoid interference between the two radio communications.

[0049] On the other hand, the second scenario is one in which the same frequency (or the same frequency range) is used for both ground-based cells and aerial cells. In the second scenario, since the frequency is shared between ground-based cells and aerial cells, it is not necessary to increase frequency resources. Therefore, the second scenario allows for the efficient use of frequency resources.

[0050] (Communication control method according to the first embodiment) In the first embodiment, we focus on the second scenario. One problem when applying the second scenario to the mobile communication system 1 is interference. For example, when UAV150-1 and 150-2 (hereinafter, when UAV150-1 and UAV150-2 are not distinguished, they may be referred to as UAV150) perform uplink communication, there are cases where the radio signal reaches not only the serving cell and its adjacent cells, but also over a wider area. In such cases, if the UAV150 and the ground UE100 are using the same frequency, the signal from the UAV150 may cause interference. Wireless communication by the UAV150 has a problem specific to UAVs in that the impact of interference is greater than when the ground UE100 performs wireless communication.

[0051] Therefore, in order to avoid interference in the second scenario, it is necessary for the mobile communication system 1 to quickly make appropriate settings for the UAV150 flying overhead.

[0052] However, in the mobile communication system 1, there is a problem in how to identify the UAV150 flying in the air in order to quickly perform the appropriate configuration.

[0053] In an LTE system, it is possible to have the HSS send an information element (Aerial UE subscription information) indicating whether or not the UE is permitted to function as an aerial UE to the MME using an S6a message. Furthermore, it is possible for the MME to send this information element to the eNB using an S1AP message. Therefore, in an LTE system, the eNB can determine whether or not the UE is permitted to function as an aerial UE (or whether the UE has the capability to function as an aerial UE).

[0054] However, the eNB cannot determine whether the UE is actually flying or not. Therefore, the eNB may not be able to identify that the UE is a UAV. Currently, there is no provision in 3GPP for the gNB200 to determine whether UE100 is a UAV150 or not in the NR. Therefore, the gNB200 may not be able to identify whether UE100 is a UAV150 or not.

[0055] Therefore, the objective of the first embodiment is to enable appropriate identification of UE100 as UAV150. Specifically, in the first embodiment, UE100 is constant Below The purpose is to enable the gNB200 to determine whether or not it is flying at a higher altitude.

[0056] Therefore, in the first embodiment, the user device (e.g., UE100) transmits altitude information regarding the user device's altitude to the base station (e.g., gNB200) either when establishing an RRC connection with the base station or after the RRC connection has been established with the base station. As a result, the gNB200, based on the altitude information of the UE100, can determine that the UE100 is flying above it, i.e., that the UE100 is a UAV150, if it detects that the UE100 is flying at an altitude exceeding a predetermined threshold. By appropriately identifying the UE100 as a UAV150, the gNB200 can quickly take appropriate action regarding the UAV150, thereby avoiding interference problems in the second scenario.

[0057] (Example of operation according to the first embodiment) Figure 7 is a diagram illustrating an example of operation according to the first embodiment.

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

[0059] Firstly, there are several methods for transmitting altitude information. For example, a UE100 in an RRC idle or RRC inactive state may send a message (Msg1) containing altitude information to the gNB200 using a random access resource (or a PRACH (Physical Random Access Channel) resource) dedicated to UAVs. The random access resource dedicated to UAVs may be pre-configured by the gNB200. Alternatively, the UE may send a Msg3 (RRC Setup Request message) containing altitude information instead of Msg1. The UE may also send a Msg5 (RRC Setup Complete message) containing altitude information. Alternatively, a UE100 in an RRC connected state may send UE-Assisted Information (UAI) containing altitude information to the gNB200. In this way, the UE100 may transmit altitude information when establishing an RRC connection with the gNB200. UE100 may transmit altitude information after the RRC connection is established. However, it is preferable for UE100 to transmit altitude information as soon as possible after the RRC connection is established.

[0060] Secondly, the information included in altitude information may include, for example, the following: Altitude information may include information indicating that UE100 has the capability to fly. Alternatively, altitude information may include information regarding the current or past altitude of UE100. Information regarding past altitude may include time information (or timestamp). Alternatively, altitude information may include information representing the altitude of UE100 using regions divided according to altitude (this information may be referred to as "region information"). Region information may consist of three regions, for example, High altitude, Low altitude, and Terrestrial, depending on the altitude. Thus, altitude information may include region information corresponding to the altitude of UE100 itself. Altitude information may be represented by the altitude obtained by an altitude sensor (or distance sensor such as radar or lidar) installed on UE100. Altitude itself may be represented by sea level. Altitude itself may be represented by elevation. Altitude itself may be represented by height from the ground.

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

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

[0063] Firstly, as a prescribed process, the gNB200 may perform a measurement configuration specifically for the UAV on the UE100 (i.e., the UAV150). The measurement configuration specifically for the UAV makes it possible to set trigger conditions (e.g., H1 or H2) for the UAV150 to send a measurement report, and to set UAV-specific information (such as location information including altitude information) to be included in the measurement report. Alternatively, the gNB200 may perform this configuration by sending an RRC message (RRCReconfiguration message or RRCResume message) containing the measurement configuration specifically for the UAV to the UAV150.

[0064] Secondly, as a predetermined process, the gNB200 may hand over the UE100 to an appropriate frequency. For example, even in the second scenario, it is possible to use separate frequencies for UAVs and ground UEs within the range of shared frequencies. If the gNB200 determines that the UE100 is a UAV150, it may hand over the UAV150 to an airborne cell using a frequency dedicated to UAVs. Specifically, to facilitate the handover of the UAV150 to the cell, a measurement configuration may be set for the UAV150 that lowers the threshold used in the event condition than the usual case.

[0065] [Second Embodiment] Next, a second embodiment will be described. In the second embodiment, the differences from the first embodiment will be the main focus of the description.

[0066] The second embodiment is an example in which a UE100 connected to a serving cell 200-1 in an RRC-connected state obtains upper-air cell information from an adjacent cell (or adjacent gNB) 200-2, and then transmits the obtained upper-air cell information to the serving cell 200-1.

[0067] Specifically, firstly, the user device (e.g., UE100) receives aerial cell information regarding an aerial cell reported from an adjacent cell (e.g., adjacent cell 200-2). Secondly, the user device transmits the aerial cell information to a serving cell (e.g., serving cell 200-1).

[0068] This allows, for example, gNB200-1 (or serving cell) to understand the airborne cell information being used by the adjacent gNB200-2 (or adjacent cell). Based on this airborne cell information, gNB200-1 can then perform interference avoidance processing for the UAV150. Thus, gNB200-1 can implement a solution to the interference problem in the second scenario.

[0069] (Example of operation according to the second embodiment) Figure 8 is a diagram illustrating an example of operation according to the second embodiment.

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

[0071] In step S21, the adjacent cell (or adjacent gNB) 200-2 to the serving cell 200-1 broadcasts a System Information Block (SIB) containing information about the aerial cell. The aerial cell information may include the cell ID of the aerial cell. Alternatively, the aerial cell information may include information about the frequency (or aerial frequency) used by the aerial cell. Alternatively, the aerial cell information may be presented in a list format, with the cell ID and / or the frequency. The adjacent cell may also broadcast cell list information representing the cell list it manages. The cell list information may include an identifier for each entry in the cell list indicating that it is an aerial cell. The cell list entry that has been assigned an identifier indicating that it is an aerial cell may also be the aerial cell information. That is, the adjacent cell 200-2 may broadcast cell list information that includes aerial cell information.

[0072] In step S22, UE100 identifies an upper-air cell in response to receiving the SIB announced in step S21. For example, UE100 may store the cell ID of an upper-air cell in memory or elsewhere and identify the upper-air cell by comparing it with the cell ID included in the upper-air cell information received from the adjacent cell 200-2.

[0073] In step S23, UE100 transmits the airborne cell information received from the adjacent cell 200-2 to the serving cell 200-1. UE100 may also transmit the airborne cell information to the serving cell 200-1 when its altitude is higher than the second threshold (or when its altitude reaches or exceeds the second threshold). This allows the serving cell 200-1 to identify UE100 as a UAV150 flying overhead. UE100 may also transmit an RRC message containing the airborne cell information to the serving cell 200-1. The second threshold may be the same as the first threshold (the threshold for determining whether or not to transmit altitude information) described in the first embodiment, or it may be a different threshold. The second threshold may, for example, be broadcast from the serving cell 200-1 in the SIB.

[0074] In step S24, if the serving cell uses a frequency different from the upper-air frequency included in the upper-air cell information received from UE100, it may perform a predetermined process. For example, there are three predetermined processes:

[0075] Firstly, serving cell 200-1 performs transmit power control to UE100 as a predetermined process. For example, if serving cell 200-1 identifies UE100 as UAV150, it may use a Transmission Power Control (TPC) command to control the UAV150 to suppress its transmit power. This makes it possible to avoid interference from radio signals transmitted from UAV150.

[0076] Secondly, as a predetermined process, serving cell 200-1 may hand over UE100 to an appropriate frequency, similar to the first embodiment. For example, if serving cell 200-1 identifies UE100 as UAV150, it may control the handover of UAV150 to an airborne cell that supports an airborne frequency.

[0077] Thirdly, serving cell 200-1 may, as a predetermined process, release UE100 from the RRC connected state to the RRC idle state or the RRC inactive state. Serving cell 200-1 may release UE100 to the RRC idle state by sending an RRC release (RRCRelease) message to UE100 in the RRC connected state. Alternatively, serving cell 200-1 may release UE100 to the RRC inactive state by sending an RRC release (RRCRelease) message including a suspend config to UE100 in the RRC connected state.

[0078] (Another example of the second embodiment) Next, we will describe other examples of the second embodiment.

[0079] In the second embodiment, an example was described in which aerial cell information relating to an aerial cell is transmitted from an adjacent cell 200-2 to a serving cell 200-1 via UE100, but the embodiment is not limited to this. For example, it is also possible for gNB200-1 and an adjacent gNB200-2 to share aerial cell information by transmitting it directly to each other without going through UE100.

[0080] Specifically, a base station (e.g., gNB200-1) either transmits information about an upper-air cell to an adjacent base station (e.g., adjacent gNB200-2) or receives information about an upper-air cell from the adjacent base station.

[0081] This allows, for example, the adjacent gNB200-2 to obtain information about the upper-air cells used by gNB200-1 (such as the cell ID or frequency of the upper-air cells used in the upper-air cells). Based on this upper-air cell information, the adjacent gNB200-2 can then prepare for interference avoidance processing for the UAV150. Thus, the adjacent gNB200-2 can implement a solution to the interference problem in the second scenario.

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

[0083] As shown in Figure 9, in step S30, gNB200-1 transmits upper-air cell information to the adjacent gNB200-2 when establishing an Xn connection with the adjacent gNB200-2 or when making a setting change to the adjacent gNB200-2. The upper-air cell information may be the same as in the second embodiment. gNB200-1 may transmit cell list information including the upper-air cell information. Regarding the transmission of upper-air cell information, gNB200-1 may transmit an Xn connection establishment request (XN SETUP REQUEST) message including the upper-air cell information to the adjacent gNB200-2. Alternatively, gNB200-1 may transmit an NG-RAN including the upper-air cell information. node A configuration update message (NG-RAN NODE CONFIGURATION UPDATE) may be sent to the adjacent gNB200-2.

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

[0085] In step S32, gNB200-1 may perform a predetermined process. The predetermined process may be, as in the second embodiment, transmission power control in the suppression direction for the UAV150. Alternatively, the predetermined process may be, as in the second embodiment, handover of the UAV150 to an upper-air cell (or upper-air frequency). Alternatively, the predetermined process may be, as in the second embodiment, release the UAV150 from the RRC connected state to the RRC idle state or RRC inactive state.

[0086] In addition, while an example of operation in the second embodiment described an example in which gNB200-1 transmits aerial cell information to the adjacent gNB200-2, the embodiment is not limited to this. For example, the adjacent gNB200-2 may transmit aerial cell information to gNB200-1 regarding the aerial cells it manages. Whether gNB200-1 transmits the aerial cell information or the adjacent gNB200-2 transmits the aerial cell information, it is possible to share aerial cell information between gNB200-1 and the adjacent gNB200-2.

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

[0088] In the third embodiment, an example is described in which a UE100 (i.e., a UAV150) 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 high altitude).

[0089] As explained in the first embodiment, a problem specific to UAVs is that wireless communication using the UAV150 is more susceptible to interference than wireless communication using the ground-based UE100. In future discussions within 3GPP, it is expected that various interference avoidance measures will be taken for the RRC-connected UAV150.

[0090] On the other hand, if interference occurs when the UAV150 executes a random access procedure, there is currently no workaround.

[0091] Therefore, the third embodiment aims to avoid interference in random access procedures. Specifically, the third embodiment aims to avoid collisions in PRACH preamble transmission.

[0092] Therefore, in the third embodiment, firstly, the base station (e.g., gNB200) sets up a random access resource dedicated to unmanned aerial vehicles (UAVs) on the user device (e.g., UE100). Secondly, the user device located at an altitude above a predetermined threshold transmits a PRACH preamble to the base station using the random access resource dedicated to unmanned aerial vehicles (UAVs).

[0093] Thus, in the third embodiment, the UE100 (or UAV150) sends the PRACH preamble to the gNB200 using a random access resource dedicated to the UAV, thereby avoiding collisions with PRACH preambles sent using other resources. Therefore, interference in the random access procedure can be avoided in the third embodiment.

[0094] The three embodiments differ in that the primary objective is interference avoidance, while the primary objective of the first embodiment is for the gNB200 to determine whether the UE100 is located at an altitude above a first threshold. However, even in the first embodiment, UE100 Since the gNB200, once it recognizes that the object is a UAV150, can configure interference avoidance measures for that UAV150, the two embodiments can be said to share the common objective of interference avoidance.

[0095] In the first embodiment, we described sending a message (Msg1) containing advanced information using a random access resource dedicated to the UAV. Such transmission becomes possible by configuring the UAV-dedicated random access resource using the gNB200.

[0096] Furthermore, 3GPP's Rel-17 introduced a common framework for PRACH Partitioning. This framework allows for the configuration of PRACH resources for each function, such as RedCap (Radio Reduced Capability), SDT (Small Data Transmission), or RAN Slicing.

[0097] (Example of operation according to the third embodiment) Figure 10 is a diagram illustrating an example of operation according to the third embodiment.

[0098] As shown in Figure 10, in step S40, gNB200 sets a dedicated PRACH resource for the UAV in UE100.

[0099] Firstly, a dedicated PRACH resource for UAVs may be configured. For example, a dedicated PRACH resource for UAVs may be added to the PRACH resource for ground-based UE100s. Alternatively, a new information element (e.g., "Aerial vehicles") indicating that it is dedicated to UAVs may be added to the information element (FeatureCombination) that represents a function or set of functions related to the random access resource. Information regarding the dedicated PRACH resource for UAVs may be configured by an information element (RACH-ConfigCommon) that represents the PRACH resource.

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

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

[0102] In step S41, UE100 selects a PRACH resource corresponding to its altitude and transmits a PRACH preamble using the selected PRACH resource. If UE100 determines that it is located at an altitude below (or less than or equal to) a predetermined threshold (i.e., on the ground), it may transmit a PRACH preamble using a normal PRACH resource used as a ground UE. Alternatively, for example, if UE100 determines that it is located at an altitude above (or exceeding) a predetermined threshold, it may transmit a PRACH preamble using one of the UAV-specific PRACH resources, depending on the altitude.

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

[0104] [Other embodiments] Each of the above-described operation flows can be performed not only independently, but also in combination of two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow. It is not necessary to execute all steps in each flow; only some steps may be executed.

[0105] In the embodiments and examples described above, an example in which the base station is an NR base station (gNB) was described, but the base station may also be an LTE base station (eNB) or a 6G base station. Furthermore, 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 an IAB node. Furthermore, UE100 may be an MT (Mobile Termination) of an IAB node.

[0106] Furthermore, the term "network node" primarily refers to a base station, but may also refer to a core network device or a 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 UE100 or gNB200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM. Alternatively, the circuits that execute each process performed by the UE100 or gNB200 may be integrated, and at least a part of the UE100 or gNB200 may be configured as a semiconductor integrated circuit (chipset, SoC: System on a chip).

[0108] The terms "based on" and "depending on" used in this disclosure do not mean "based solely on" or "depending solely on" unless otherwise specified. "Based on" means both "based solely on" and "at least partially on." Similarly, "depending on" means both "at least partially on" and "at least partially on." Furthermore, the terms "include" and "comprise" do not mean to include only the listed items, but may include only the listed items or may include additional items in addition to the listed items. Also, the term "or" used in this disclosure is not intended to mean exclusive OR. Moreover, any reference to elements using designations such as "first," "second," etc., used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated by the context that they are not.

[0109] Please refer to the above drawing. And actually Although the implementation methods have been described in detail, the specific configuration is not limited to those described above, and various design changes can be made within the scope that does not deviate from the gist of the invention. Furthermore, it is possible to combine all or part of each embodiment, each operation, each process, and each step, as long as they do not contradict each other.

[0110] This application claims priority to U.S. Provisional Application No. 63 / 409868 (filed September 26, 2022), the entirety of which is incorporated into the specification of this application.

[0111] (Note) (Note 1) A communication control method in a mobile communication system, The user device has a step of transmitting altitude information regarding the user device 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. Communication control method.

[0112] (Note 2) The aforementioned transmission step includes the user device sending a message containing the altitude information to the network node using random access resources dedicated to unmanned aerial vehicles (UAVs). The communication control method described in Appendix 1.

[0113] (Note 3) The altitude information includes information indicating that the user device has flight capability. A communication control method as described in either Appendix 1 or Appendix 2.

[0114] (Note 4) The aforementioned advanced information includes information regarding the current or past advanced status of the user device. A communication control method as described in any of Appendix 1 to Appendix 3.

[0115] (Note 5) The aforementioned altitude information includes information that represents the altitude of the user device using regions divided according to that altitude. A communication control method as described in any of Appendix 1 to Appendix 4.

[0116] (Note 6) The aforementioned transmission step includes the step of transmitting the altitude information when the user device's altitude is equal to or greater than a first threshold. A communication control method as described in any of Appendix 1 to Appendix 5.

[0117] (Note 7) A communication control method in a mobile communication system, The user device receives upper-air cell information regarding an upper-air cell reported from an adjacent cell, The user device includes the step of transmitting the aerial cell information to the serving cell. Communication control method.

[0118] (Note 8) The aforementioned transmission step includes the step of the user device transmitting the above-air cell information when the altitude of the user device is higher than the second threshold. The communication control method described in Appendix 7.

[0119] (Note 9) A communication control method in a mobile communication system, The network node has the step of either transmitting aerial cell information relating to an aerial cell to an adjacent network node, or receiving the aerial cell information from the adjacent network node. Communication control method.

[0120] (Note 10) The transmission step includes the step of transmitting the airborne cell information to the adjacent network node when the network node establishes a connection with the adjacent network node and when it makes configuration changes to the adjacent network node. The communication control method described in Appendix 9.

[0121] (Note 11) The above-mentioned upper-air cell information includes the cell ID of the upper-air cell or the frequency used by the upper-air cell. A communication control method as described in any of Appendix 7 to Appendix 10.

[0122] (Note 12) A communication control method in a mobile communication system, The network node configures a random access resource dedicated to unmanned aerial vehicles (UAVs) on the user device, The user device, located at an altitude above a predetermined threshold, transmits a PRACH preamble to the network node using a random access resource dedicated to the unmanned aerial vehicle (UAV). Communication control method.

[0123] (Note 13) The random access resources dedicated to the aforementioned unmanned aerial vehicle (UAV) are different resources depending on the altitude of the user device. The communication control method described in Appendix 12.

Claims

1. A communication control method in a mobile communication system, The user device transmits altitude information regarding the user device to the network node either when establishing an RRC connection to the network node or after the RRC connection to the network node has been established. The aforementioned transmission includes the user device sending a message containing the altitude information to the network node using random access resources dedicated to unmanned aerial vehicles (UAVs). Communication control method.

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

3. The aforementioned advanced information includes information regarding the current or past advanced status of the user device. The communication control method according to claim 1.

4. The aforementioned altitude information includes information representing the altitude of the user device using regions divided according to altitude. The communication control method according to claim 1.

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

6. A user device in a mobile communication system, The system includes a transmitting unit that transmits altitude information relating to the user device to the network node either when establishing an RRC connection to the network node or after an RRC connection has been established to the network node. The transmitting unit transmits a message containing the altitude information to the network node using a random access resource dedicated to the unmanned aerial vehicle (UAV). User device.

Images