Communication control method and user device

Abstract

A communication control method according to one aspect of the present invention is a communication control method in a mobile communication system. The communication control method comprises a step of transmitting to a network node, by a user device positioned at an altitude higher than or equal to a predetermined threshold value, a measurement report according to a travel distance of the user device.

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 is defined (for example, Non-Patent Document 1 and Non-Patent Document 2). For example, the Aerial UE is capable of reporting altitude and reporting position information including vertical velocity and horizontal velocity. 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 equipment located at an altitude equal to or higher than a predetermined threshold transmits a measurement report to a network node (or a network apparatus) in accordance with a movement distance of the user equipment.

[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: the user device determining a timer value according to the user device's movement speed; and the user device transmitting a measurement report to a network node when the count value counted by the timer reaches the timer value. [Brief explanation of the drawing]

[0006] [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 another example of operation according to the first embodiment. [Figure 9] Figure 9 is a diagram illustrating another example of operation according to the first embodiment. [Figure 10] Figure 10 is a diagram illustrating an example of operation according to the second embodiment. [Modes for carrying out the invention]

[0007] 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.

[0008] [First Embodiment]

[0009] (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.

[0010] 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.

[0011] 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).

[0012] 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").

[0013] 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.

[0014] 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.

[0015] 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.

[0016] The receiving unit 110 performs various types of reception 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.

[0017] The transmitting unit 120 performs various types of transmission 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 the radio signal from the antenna.

[0018] The control unit 130 performs various types of control and processing in the UE 100. Such processing includes processing 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 processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation, encoding / decoding, and the like of the baseband signal. The CPU executes programs stored in the memory to perform various types of processing. Note that the control unit 130 may perform each process or each operation in the UE 100 in each embodiment described below.

[0019] FIG. 3 is a diagram illustrating a configuration of a gNB 200 (base station) according to the first embodiment. The gNB 200 includes a transmitting unit 210, 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 performs communication with the CN 20.

[0020] The transmitting unit 210 performs various types of transmission 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 the radio signal from the antenna.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Figure 4 shows the configuration of the protocol stack for the user plane's wireless interface that handles data.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0030] 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.

[0031] Figure 5 shows the configuration of the protocol stack of the wireless interface of the control plane that handles signaling (control signals).

[0032] 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.

[0033] 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.

[0034] 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).

[0035] (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.

[0036] 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.

[0037] 3GPP has established the following provisions to support aerial UE (Aircraft Unification) functionality:

[0038] 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.

[0039] 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.

[0040] Thirdly, whether or not a flying UE is supported (or whether or not it is permitted to function 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 the UE is permitted to function as a flying UE.

[0041] 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.

[0042] The 3GPP regulations in this way assume that flight UEs (i.e., UAVs) will be used with LTE systems.

[0043] 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.

[0044] (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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] (Communication control method according to the first embodiment) The first embodiment is an embodiment relating to a measurement report.

[0050] The measurement report is information that is sent, for example, when UE100 meets predetermined conditions related to event triggers. Upon receiving the measurement report, gNB200 (or eNB) can hand over UE100 to an adjacent cell based on the measurement report.

[0051] Here, let's assume that in an LTE system, event H1 is set as an event condition for a flying UE. In such a case, the flying UE will satisfy the event condition for event H1 as long as its altitude exceeds the threshold. Therefore, the flying UE may continue to send measurement reports at the report interval (the periodic interval at which measurement reports are sent). In other words, the flying UE sends measurement reports more often than a ground UE, resulting in a problem of increased overhead. It is expected that a similar problem will arise when specific event conditions (e.g., event H1 or event H2) are introduced in NR.

[0052] On the other hand, regarding measurement reports, it is also possible to solve the overhead issue of measurement reporting by setting a prohibit timer and not sending measurement reports during that time. A prohibit timer is, for example, a period during which no processing is performed.

[0053] However, even if a no-go time is set for the UAV150, the distance traveled during that time will vary depending on the UAV150's speed, and the wireless conditions may change significantly. If the UAV150 moves too far, a certain number of radio link failures (RLF) or handover failures (HOF) may occur. Therefore, it may not be possible for the mobile communication system 1 to perform avoidance processing for RLF or HOF.

[0054] Therefore, the objective of the first embodiment is to appropriately suppress the number of measurement reports for the UAV150.

[0055] Therefore, in the first embodiment, a user device (e.g., UAV150) located at an altitude above a predetermined threshold transmits a measurement report to a base station (e.g., gNB200) according to the distance traveled by the user device.

[0056] Since the UAV150 can transmit measurement reports according to the distance traveled, for example, the number of measurement reports from the UAV150 can be reduced compared to when the prohibited time is less than a predetermined time. Also, since the UAV150 can transmit measurement reports according to the distance traveled, for example, measurement reports can be transmitted appropriately according to the wireless conditions compared to when the prohibited time is longer than a predetermined time. Therefore, in the first embodiment, it is possible to appropriately reduce the number of measurement reports.

[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, the gNB200 sets a distance threshold for the UAV150. The distance threshold is, for example, a threshold used by the UAV150 to determine whether or not to send a measurement report based on its own travel distance. The distance threshold may be expressed in units of length (meters, centimeters, or yards, etc.). The distance threshold may also be expressed in latitude and longitude. Hereinafter, the distance threshold will be described assuming it is expressed in units of length (e.g., meters). The gNB200 may set the distance threshold by sending an RRCSetup message containing the distance threshold to the UAV150. Alternatively, the gNB200 may set the distance threshold by broadcasting System Information (SIB) containing the distance threshold. Alternatively, the gNB200 may set the distance threshold for the UAV150 by sending a measurement configuration containing the distance threshold to the UAV150 using an RRC message (e.g., an RRCReconfiguration message or an RRCResume message).

[0059] In step S11, the UAV150 measures the distance traveled. The UAV150 may measure the distance traveled by measuring the speed per unit time using a speed sensor and multiplying (or integrating) the speed by the time measured by a timer. The UAV150 may also measure the distance traveled using a GNSS (Global Navigation Satellite System) receiver. The distance traveled may be expressed in a planar direction (longitudinal and / or horizontal direction, or latitude and longitude direction). The distance traveled may also be expressed in a three-dimensional direction (height direction). The distance threshold may also be expressed in the same direction as the distance traveled.

[0060] In step S12, the UAV150 determines whether the travel distance exceeds the distance threshold (or whether the travel distance is greater than or equal to the distance threshold). If the travel distance exceeds the distance threshold in step S12 (Yes in step S12), the process proceeds to step S13. On the other hand, if the travel distance does not exceed the distance threshold in step S12 (No in step S12), step S12 is repeated until the travel distance exceeds the distance threshold.

[0061] In addition, the conditions for sending measurement reports according to the distance traveled (specifically, step S12) may be referred to as the "distance traveled conditions" below.

[0062] In step S13, the UAV150 sends a measurement report to the gNB200. However, the UAV150 may use either a prohibit timer or a report interval in conjunction with the travel distance condition when sending the measurement report. That is, the UAV150 may send a measurement report even if the prohibit timer (or time interval) has not expired, if the travel distance exceeds the distance threshold. The UAV150 may reset the timer count value that counts the prohibit timer (or time interval) when it sends a measurement report. When the UAV150 sends a measurement report, it resets the measured travel distance and resumes measuring the travel distance.

[0063] Furthermore, even if the distance traveled by the UAV150 does not exceed the distance threshold (or the distance traveled is less than or equal to the distance threshold) (No in step S12), the UAV150 may still transmit a measurement report once the prohibited time (or time interval) has expired. For example, if the UAV150 is hovering in the air, the UAV150 does not move, so the distance traveled will not exceed the distance threshold. Even in such cases, the prohibited time (or time interval) may be used to ensure that the UAV150 transmits a measurement report at predetermined intervals (i.e., each time the prohibited time or time interval expires).

[0064] (Another example of the first embodiment 1) Next, we will describe another example 1 of the first embodiment. This description of another example 1 of the first embodiment will focus on the differences from the first embodiment.

[0065] Another example of the first embodiment is one in which the measurement of the travel distance (step S11 in Figure 7) described in the first embodiment is started when an event condition is met. Specifically, the user device (e.g., UAV150) starts measuring the travel distance when it determines that the event condition is met. This makes it possible for the UAV150, for example, to transmit a measurement report using both the event condition and the travel distance condition.

[0066] Figure 8 is a diagram illustrating an example of operation in another example 1 of the first embodiment. In Figure 8, the same processing parts as in the first embodiment are denoted by the same reference numerals.

[0067] As shown in Figure 8, once the distance threshold is set (step S10), the UAV150 determines in step S20 whether or not the event condition is met. If the UAV150 determines that the event condition is met (Yes in step S20), it starts measuring the distance traveled (step S11). On the other hand, if the UAV150 determines that the event condition is not met (No in step S20), it repeats the process until the event condition is met.

[0068] The event used in the event condition can be any event, including events defined by 3GPP. For example, such events may be Event H1 or Event H2 as described above. Another example of such an event is Event A3. Event A3 is an event that indicates that the radio quality of an adjacent cell is higher than the radio quality of the primary cell.

[0069] The gNB200 may configure the UAV150 to measure the distance traveled when event conditions are met. In this case, the gNB200 may configure this by sending a measurement configuration to the UAV150 that includes the event conditions and the distance threshold. Alternatively, the gNB200 may configure this by sending a measurement configuration to the UAV150 that includes information indicating that the distance traveled should be measured when event conditions are met.

[0070] Furthermore, the UAV150 may submit a measurement report when the event condition is met (Yes in step S20). The UAV150 may then start measuring the distance traveled, using the submission of the measurement report as an event condition. Since the event condition is met when the UAV150 submits a measurement report in step S13, it may restart measuring the distance traveled. In this case, the UAV150 will repeatedly submit a measurement report and then measure the distance traveled.

[0071] (Another example of the first embodiment 2) Next, we will describe another example 2 of the first embodiment. The description of this other example 2 of the first embodiment will focus on the differences from the first embodiment.

[0072] Another example 2 of the first embodiment is an example in which the UAV150 transmits a measurement report when both the event condition and the travel distance condition are met. Specifically, the user device (e.g., UAV150) transmits a measurement report to the base station (e.g., gNB200) based on the travel distance (e.g., travel distance condition) and the event condition. This makes it possible for the UAV150 to transmit a measurement report using both the event condition and the travel distance condition in combination, even in another example 2 of the first embodiment.

[0073] Figure 9 is a diagram illustrating an example of operation in another example 2 of the first embodiment.

[0074] As shown in Figure 9, in step S30, gNB200 sets UE100 to use both the travel distance condition and the event condition. This setting may be done by gNB200 sending a measurement configuration, including information indicating that the travel distance condition and the event condition will be used together, to UAV150 using an RRC message. Alternatively, gNB200 may send a measurement configuration, including the distance threshold and applicable events, to UAV150 using an RRC message. The events used in the event condition may be events defined by 3GPP (for example, event A3, event A5, event H1, or event H2, etc.), as in other examples 1 of the first embodiment.

[0075] In step S31, UAV150 evaluates the event conditions. If the event conditions are met, UAV150 enters the start (enter) state. On the other hand, if the event conditions are not met, UAV150 leaves the state.

[0076] In step S32, the UAV150 evaluates the travel distance condition. If the travel distance of the UAV150 is greater than or equal to the distance threshold (or if the UAV150 exceeds the distance threshold), the UAV150 enters the start (enter) state. On the other hand, if the travel distance of the UAV150 is less than the distance threshold (or if the travel distance is less than or equal to the distance threshold), the UAV150 leaves the end (leave) state. The measurement of the travel distance may be the same as in the first embodiment (step S11). The order of steps S31 and S32 may be reversed.

[0077] In step S33, the UAV150 determines whether both the event condition and the travel distance condition are in an initiated state. If both conditions are in an initiated state (Yes in step S33), the UAV150 sends a measurement report to the gNB200 (step S34). In other words, the UAV150 sends a measurement report to the gNB200 if the travel distance exceeds the distance threshold and the event condition is met. On the other hand, if neither of the two conditions are in an initiated state (No in step S33), the UAV150 returns to step S31 and repeats the process described above. In other words, the UAV150 does not send a measurement report if the travel distance is less than or equal to the distance threshold, or if the event condition is not met.

[0078] [Second Embodiment] Next, a second embodiment will be described. The second embodiment will also be described focusing on the differences from the first embodiment.

[0079] In the second embodiment, an example is described in which the prohibited time (or time interval) is changed according to the movement speed of the UAV150 (hereinafter, such a change may be referred to as "scaling"). Prohibited time teeth This refers to the prohibit timer described in the first embodiment. The time interval refers to the report interval for reporting measurement reports, as described in the first embodiment.

[0080] Specifically, firstly, the user device (e.g., UAV150) determines a timer value (e.g., a forbidden time or time interval) according to the user device's movement speed. Secondly, the user device transmits a measurement report to the base station (e.g., gNB200) when the count value counted by the timer reaches the timer value.

[0081] As a result, for example, the UAV150 can transmit measurement reports according to its speed, making it possible to control the number of measurement reports transmitted compared to when the timer value is constant. Therefore, the mobile communication system 1 according to the second embodiment can appropriately suppress the number of measurement reports.

[0082] The prohibited time (or time interval) can be scaled as follows, for example: When the UAV150's movement speed is above the speed threshold (i.e., when the UAV150 is moving at high speed), the UAV150 sets the timer value to be below the time threshold. Also, when the UAV150's movement speed is below the speed threshold (i.e., when the UAV150 is moving at low speed), the UAV150 sets the timer value to be above the time threshold. This scaling allows for an appropriate reduction in the number of measurement reports compared to when the prohibited time or time interval is constant, because the timer value is below the time threshold when the UAV150's movement speed is above the speed threshold (i.e., when the UAV150 is moving at high speed). Furthermore, this scaling allows the UAV150 to appropriately transmit measurement reports even when hovering, because the timer value is above the time threshold when the UAV150's movement speed is below the speed threshold (i.e., when the UAV150 is moving at low speed).

[0083] (Example of operation according to the second embodiment) Figure 10 is a diagram illustrating an example of operation according to the second embodiment.

[0084] As shown in Figure 10, in step S40, the gNB200 sets the timer value to the UAV150. The timer value is represented by either a prohibit timer or a report interval for reporting measurement reports. The gNB200 may also set the timer value by sending the measurement configuration, including the timer value, to the UAV150 using an RRC message.

[0085] In step S41, the gNB200 sets the scaling value to UAV 150 Set to this value. The gNB200 may also set the scaling value by sending the measurement settings, including the scaling value, to the UAV150 using an RRC message.

[0086] Note that the order of steps S40 and S41 may be reversed. Steps S40 and S41 may be combined into one setting. If the two settings are combined into one, the gNB200 may send a single measurement setting, including the timer value and scaling value, to the UAV150 using a single RRC message.

[0087] In step S42, the UAV150 determines the timer value. The UAV150 determines the timer value by scaling the set timer value with a scaling value corresponding to the travel speed, for example. Specifically, the UAV150 may determine the timer value as follows.

[0088] Firstly, the UAV150 may determine the timer value by multiplying the scaling value by the UAV150's movement speed and dividing the set timer value by the multiplier ([Set Timer Value] ÷ {[Scaling Value] × [UAV150's Movement Speed]}). The faster the UAV150's movement speed, the smaller the timer value becomes. The timer value is determined according to the movement speed. The UAV150 may also determine the timer value by measuring its own movement speed and substituting each value into the above formula. The method for measuring the movement speed may be the same as in the first embodiment.

[0089] Secondly, the UAV150 may determine the timer value by multiplying the set timer value by the scaling value for each movement state of the UAV150 ([Set Timer Value] × [Scaling Value for Each Movement State of the UAV150]). The movement state of the UAV150 refers to a state classified according to the movement speed of the UAV150. For example, the movement state of the UAV150 may be "stationary" when the movement speed of the UAV150 is "0" or less than the first velocity threshold, "slow movement" when the movement speed of the UAV150 is greater than or equal to the first velocity threshold and less than or equal to the second velocity threshold (first velocity threshold < second velocity threshold), and "high-speed movement" when the movement speed of the UAV150 exceeds the second velocity threshold. Also, for example, the scaling value set by the gNB200 may be "1" when "stationary", "0.5" when "slow movement", and "0.2" when "high-speed movement". The UAV150 measures its own speed, checks its movement status according to the speed, and determines the timer value using a scaling value corresponding to the movement status. The method for measuring the speed may be the same as in the first embodiment.

[0090] In step S43, the UAV150 starts counting using a timer in response to the transmission of the measurement report. The UAV150 may start counting using a timer at a predetermined timing.

[0091] In step S44, the UAV150 determines whether the timer count value has reached the timer value (i.e., whether the timer value has expired).

[0092] If the count value reaches the timer value (Yes in step S45), the UAV150 sends a measurement report to the gNB200 in step S46. In other words, the UAV150 sends a measurement report in response to the timer expiring.

[0093] On the other hand, if the count value does not reach the timer value (No in step S45), the UAV150 waits until the count value reaches the timer value (No in step S45). In other words, the UAV150 waits to send the measurement report until the timer expires.

[0094] In addition, Timer If the movement state of the UAV150 changes while the timer is running (i.e., while the timer is operating), the UAV150 may change the timer value. If the timer value is changed, the timer count may be restarted without being reset. Alternatively, if the timer value is changed, the timer may be reset, indicating that the timer has expired (or the count value has reached the timer value).

[0095] [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. 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.

[0096] 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).

[0097] 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).

[0098] The phrases “based on” and “depending on / in response to” 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.” The terms “include,” “comprise,” and variations thereof do not mean that only the listed items are included; they mean that only the listed items may be included, or that additional items may be included in addition to the listed items. Furthermore, the term “or” used in this disclosure is not intended to mean exclusive OR. Additionally, 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.

[0099] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the gist of the work. 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.

[0100] This application claims priority to U.S. Provisional Application No. 63 / 410362 (filed September 27, 2022), the entirety of which is incorporated into the specification of this application.

[0101] (Note) (Note 1) A communication control method in a mobile communication system, The process includes the step of a user device located at an altitude above a predetermined threshold transmitting a measurement report to a network node according to the distance traveled by the user device. Communication control method.

[0102] (Note 2) The transmission step includes the user device transmitting the measurement report to the network node when the travel distance exceeds a distance threshold. The communication control method described in Appendix 1.

[0103] (Note 3) The step of transmitting the measurement report to the network node when the travel distance exceeds the distance threshold includes the step of the user device transmitting the measurement report to the network node at predetermined intervals when the travel distance is less than or equal to the distance threshold. The communication control method described in Appendix 1 or Appendix 2.

[0104] (Note 4) The aforementioned predetermined time is either the prohibition period or the time interval for reporting the measurement report. A communication control method as described in any of Appendix 1 to Appendix 3.

[0105] (Note 5) The network node further comprises the step of setting the distance threshold to the user device. A communication control method as described in any of Appendix 1 to Appendix 4.

[0106] (Note 6) The transmission step includes a step in which the user device determines that the event condition is met and starts measuring the travel distance. A communication control method as described in any of Appendix 1 to Appendix 5.

[0107] (Note 7) The transmission step includes the user device transmitting the measurement report to the network node based on the travel distance and event conditions. A communication control method as described in any of Appendix 1 to Appendix 6.

[0108] (Note 8) The step of transmitting the measurement report to the network node based on the travel distance and the event conditions includes the step of transmitting the measurement report to the network node if the user device has traveled more than the distance threshold and the event conditions are met. A communication control method as described in any of Appendix 1 to Appendix 7.

[0109] (Note 9) The network node further includes the step of setting the user device to use the travel distance and the event conditions in combination. A communication control method as described in any of Appendix 1 to Appendix 8.

[0110] (Note 10) A communication control method in a mobile communication system, The user device determines a timer value according to the movement speed of the user device, The user device includes the step of sending a measurement report to a network node when the count value counted by the timer reaches the timer value. Communication control method.

[0111] (Note 11) The aforementioned determination step includes the step of setting the timer value to less than the time threshold when the moving speed of the user device is greater than or equal to the speed threshold, and setting the timer value to greater than or equal to the time threshold when the moving speed is less than the speed threshold. The communication control method described in Appendix 10.

[0112] (Note 12) The network node further includes the step of setting a set timer value and a scaling value on the user device. The aforementioned determination step includes the user device determining the timer value as a value obtained by scaling the set timer value by the scaling value corresponding to the movement speed. The communication control method described in Appendix 10 or Appendix 11.

Claims

1. A communication control method in a mobile communication system, When it is determined that a user device located at an altitude above a predetermined threshold satisfies the event conditions related to wireless quality, the measurement of the distance traveled is initiated. The user device transmits a measurement report to a network node according to the measured distance traveled. Communication control method.

2. The aforementioned transmission includes the user device transmitting the measurement report to the network node when the travel distance exceeds a distance threshold. The communication control method according to claim 1.

3. Sending the measurement report to the network node when the travel distance exceeds the distance threshold includes the user device sending the measurement report to the network node at predetermined intervals when the travel distance is less than or equal to the distance threshold. The communication control method according to claim 2.

4. The aforementioned predetermined time is either the prohibition period or the time interval for reporting the measurement report. The communication control method according to claim 3.

5. The network node further includes setting the distance threshold to the user device. The communication control method according to claim 2.

6. The aforementioned transmission includes the user device transmitting the measurement report to the network node based on the travel distance and event conditions. The communication control method according to claim 1.

7. Transmitting the measurement report to the network node based on the travel distance and the event conditions includes the user device transmitting the measurement report to the network node if the travel distance exceeds a distance threshold and the event conditions are met. The communication control method according to claim 6.

8. The network node further includes setting the user device to use the travel distance and the event conditions in combination. The communication control method according to claim 6.

9. A communication control method in a mobile communication system, The user device determines the timer value that defines the transmission time of the measurement report by multiplying the set timer value by a scaling value of the movement state determined according to the movement speed of the user device, The user device transmits the measurement report to the network node when the count value counted by the timer reaches the timer value. Communication control method.

10. A user device in a mobile communication system, The device has a transmitting unit that, when located at an altitude above a predetermined threshold, determines that the event conditions related to wireless quality are met, starts measuring the distance traveled, and transmits a measurement report to a network node according to the measured distance traveled. User device.

11. A user device in a mobile communication system, A control unit determines a timer value that specifies the transmission time of the measurement report as a value obtained by multiplying the set timer value by a scaling value of the movement state determined according to the movement speed of the user device, The system includes a transmission unit that transmits the measurement report to a network node when the count value counted by the timer reaches the timer value. User device.

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