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

Communication Control Method

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

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

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

[0004] A communication control method according to one aspect is a communication control method in a mobile communication system, the communication control method comprising a step of transmitting a measurement report to a network node (or a network device) by a user equipment located at an altitude equal to or higher than a predetermined threshold, the measurement report corresponding to a movement distance of the user equipment.

[0005] According to one aspect, there is provided a communication control method in a mobile communication system, the communication control method including the steps of: determining, by a user equipment, a timer value according to a moving speed of the user equipment; and transmitting, by the user equipment, a measurement report to a network node when a count value counted by the timer reaches the timer value.

[0006] FIG. 1 is a diagram illustrating an example of the configuration of a mobile communication system according to the first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a UE (user equipment) according to the first embodiment. FIG. 3 is a diagram illustrating an example of the configuration of a gNB (base station) according to the first embodiment. FIG. 4 is a diagram illustrating an example of the configuration of a protocol stack related to a user plane according to the first embodiment. FIG. 5 is a diagram illustrating an example of the configuration of a protocol stack related to a control plane according to the first embodiment. FIG. 6 is a diagram illustrating an example of a cell configuration according to the first embodiment. FIG. 7 is a diagram illustrating an example of an operation according to the first embodiment. FIG. 8 is a diagram illustrating another example of an operation according to the first embodiment. FIG. 9 is a diagram illustrating another example of an operation according to the second embodiment. FIG. 10 is a diagram illustrating an example of an operation according to the second embodiment.

[0007] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0008] [First embodiment]

[0009] (Configuration of mobile communication system) Fig. 1 is a diagram showing the configuration of a mobile communication system according to the first embodiment. The mobile communication system 1 conforms to the 5th Generation System (5GS) of the 3GPP standard. Although the following description will be given using 5GS as an example, the mobile communication system may also be at least partially applied to an LTE (Long Term Evolution) system. The mobile communication system may also be at least partially applied to a 6th Generation (6G) system.

[0010] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. Furthermore, the 5GC 20 may be simply referred to as the core network (CN) 20.

[0011] The UE 100 is a mobile wireless communication device. The UE 100 may be any device that is used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone) and / or a tablet terminal, a notebook PC, a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0012] The NG-RAN 10 includes a base station (called a "gNB" in a 5G system) 200. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, and the like. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource for wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0013] In addition, the gNB 200 can also be connected to the EPC (Evolved Packet Core), which is the LTE core network. An LTE base station (eNB: evolved Node B) can also be connected to the 5GC 20. The LTE base station and the gNB 200 can also be connected via an inter-base station interface.

[0014] The 5GC20 includes an Access and Mobility Management Function (AMF) and a User Plane Function (UPF) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and the UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0015] 2 is a diagram illustrating an example of the configuration of a UE 100 (user equipment) according to the first embodiment. The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit that performs wireless communication with the gNB 200.

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

[0018] The control unit 130 performs various controls and processes in the UE 100. Such processes include processes of each layer described below. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processes by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. Note that the control unit 130 may perform each process or operation in the UE 100 in each of the embodiments described below.

[0019] 3 is a diagram showing the configuration of a gNB 200 (base station) according to the first embodiment. The gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240. The transmitter 210 and the receiver 220 constitute a wireless communication unit that performs wireless communication with the UE 100. The backhaul communication unit 240 constitutes a network communication unit that communicates with the CN 20.

[0020] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[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 a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0022] The control unit 230 performs various controls and processes in the gNB 200. Such processes include processes for each layer described below. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processes by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. Note that the control unit 230 may perform each process or operation in the gNB 200 in each of the embodiments described below.

[0023] The backhaul communication unit 240 is connected to adjacent base stations via an Xn interface, which is an interface between base stations. The backhaul communication unit 240 is connected to the AMF / UPF 300 via an NG interface, which is an interface between a base station and a core network. Note that the gNB 200 is composed of a CU (Central Unit) and a DU (Distributed Unit) (i.e., functionally divided), and the two units may be connected by an F1 interface, which is a fronthaul interface.

[0024] FIG. 4 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0025] The user plane radio interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0026] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on a physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires the successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from gNB200 has a CRC parity bit scrambled by the RNTI added.

[0027] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100.

[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 RLC layer of the UE 100 and the RLC layer of the gNB 200 via a logical channel.

[0029] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0030] The SDAP layer maps IP flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0031] FIG. 5 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

[0032] The protocol stack of the radio interface of the control plane has a Radio Resource Control (RRC) layer and a Non-Access Stratum (NAS) instead of the SDAP layer shown in FIG.

[0033] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0034] The NAS, which is located above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS of the UE 100 and the NAS of the AMF 300. Note that the UE 100 has an application layer and the like in addition to the radio interface protocol. Also, the layer below the NAS is called an Access Stratum (AS).

[0035] (UAV) Here, an unmanned aerial vehicle (UAV: Unmanned Aerial Vehicle or Uncrewed Aerial Vehicle; hereinafter, "unmanned aerial vehicle" may be referred to as "UAV") according to the first embodiment will be described.

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

[0037] In 3GPP, the following specifications are provided as functions to support an aerial UE:

[0038] First, the flying UE can report its altitude. For example, the flying UE can report its altitude when its altitude is above or below a threshold. At this time, the flying UE can also report its location information. The location information can include the horizontal and vertical speed of the flying UE.

[0039] Second, the LTE system network (E-UTRAN) can request the flying UE to report flight route information. The flight route information represents waypoints (passing point information or point information) on the route of the flying UE. The flight route information may include multiple waypoints. The waypoints are represented as three-dimensional position information. The flying UE may report time information (timestamp) for each waypoint by including it in the flight route information.

[0040] Third, 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 subscription information for each user. A Home Subscriber Server (HSS) in an LTE system stores subscriber information for each user. Whether or not a flying UE is supported is included in the subscription information. The subscription information is transmitted from the HSS to an eNB, which is a base station in the LTE system, under the control of a Mobility Management Entity (MME). The eNB can determine whether or not the UE is permitted to function as a flying UE.

[0041] Fourth, the event H1 and the event H2 can be used as trigger conditions for a measurement report. The event H1 represents an event condition when the altitude of the flying UE exceeds a threshold. Meanwhile, the event H2 represents an event condition when the altitude of the flying UE falls below the threshold. These event conditions are determined to be satisfied using a hysteresis value, an offset value, and a threshold value in addition to the altitude.

[0042] The 3GPP specifications are based on the assumption that flying UEs (i.e., UAVs) will be used in the LTE system.

[0043] Meanwhile, 3GPP has begun discussions on introducing UAVs into NR (New Radio). Regarding UAVs, 3GPP has agreed to use the above-mentioned events H1 and H2, to report the altitude, position, and speed of the UAV, and to report the flight path plan.

[0044] (Terrestrial Cells and Aerial Cells) For example, assume that terrestrial cells and aerial cells coexist within a network. Fig. 6 is a diagram showing an example of a cell configuration in such a case.

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

[0046] Here, in order for the UEs 100-1 to 100-4 to perform appropriate wireless communication in the ground cell and for the UAVs 150-1 and 150-2 to perform appropriate wireless communication in the air cell, the following two scenarios are assumed.

[0047] In the first scenario, a dedicated frequency is assigned to the air cell, and different frequencies are used for the ground cell and the air cell. In the first scenario, for example, wireless communication by UAVs 150-1 and 150-2 and wireless communication by UEs 100-1 to 100-4 are performed using different frequencies, so that interference between the two wireless communications can be avoided.

[0048] On the other hand, the second scenario is a scenario in which the same frequency (or the same frequency range) is used in the terrestrial cell and the aerial cell. In the second scenario, since the terrestrial cell and the aerial cell share the same frequency, there is no need to increase frequency resources. Therefore, in the second scenario, frequency resources can be used more effectively.

[0049] (Communication Control Method According to First Embodiment) The first embodiment is an embodiment related to a measurement report.

[0050] The measurement report is, for example, information transmitted when the UE 100 satisfies a predetermined condition related to an event trigger. The gNB 200 (or eNB) that receives the measurement report can hand over the UE 100 to a neighboring cell based on the measurement report.

[0051] Here, assume that an event H1 is set as an event condition for a flying UE in an LTE system. In such a case, the flying UE will satisfy the event condition of event H1 as long as the flying UE's altitude exceeds a threshold. Therefore, the flying UE may continue to transmit measurement reports at a report interval (report interval) (for example, a periodic interval for transmitting measurement reports). In other words, compared to ground UEs, flying UEs transmit measurement reports more frequently, resulting in a problem of increased overhead. It is expected that a similar problem will arise when a specific event condition (for example, event H1 or event H2) is introduced in NR.

[0052] On the other hand, it is also possible to solve the problem of overhead of measurement reports by providing a prohibition timer for measurement reports and not transmitting measurement reports during the prohibition timer. The prohibition timer is, for example, a time during which no processing is performed.

[0053] However, even if a prohibition time is set for the UAV 150, the distance traveled during the prohibition time may vary depending on the speed of the UAV 150, and the radio conditions may also change significantly. If the UAV 150 moves too much, a radio link failure (RLF) or a handover failure (HOF) may occur more than a certain number of times. Therefore, in the mobile communication system 1, it may not be possible to perform a process to avoid the RLF or the HOF.

[0054] Therefore, the first embodiment aims to appropriately suppress the number of measurement reports to UAV 150.

[0055] Therefore, in the first embodiment, a user device (e.g., UAV 150) located at an altitude above a predetermined threshold transmits a measurement report to a base station (e.g., gNB 200) according to the travel distance of the user device.

[0056] Since UAV 150 can transmit measurement reports according to the travel distance, the number of measurement reports from UAV 150 can be reduced compared to when, for example, the prohibition time is less than a predetermined time. Also, since UAV 150 can transmit measurement reports according to the travel distance, it can appropriately transmit measurement reports according to the radio conditions compared to when, for example, the prohibition time is equal to or greater than a predetermined time. Therefore, in the first embodiment, it is possible to appropriately reduce the number of measurement reports.

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

[0058] As shown in FIG. 7 , in step S10, the gNB 200 sets a distance threshold to the UAV 150. The distance threshold is, for example, a threshold used by the UAV 150 to determine whether or not to transmit a measurement report depending on its own moving distance. The distance threshold may be expressed in units of length (meters, centimeters, yards, etc.). The distance threshold may also be expressed in latitude and longitude. In the following, the description will be given assuming that the distance threshold is expressed in units of length (e.g., meters). The gNB 200 may set the distance threshold by transmitting an RRC establishment (RRCSetup) message including the distance threshold to the UAV 150. Alternatively, the gNB 200 may set the distance threshold by broadcasting system information (SIB) including the distance threshold. Alternatively, gNB200 may set the distance threshold to UAV150 by sending a measurement configuration including the distance threshold to UAV150 using an RRC message (e.g., an RRCReconfiguration message or an RRCResume message).

[0059] In step S11, the UAV 150 measures the traveled distance. The UAV 150 may measure the speed per unit time using a speed sensor and measure the traveled distance by multiplying (or integrating) the speed by the time measured by a timer. The UAV 150 may measure the traveled distance using a GNSS (Global Navigation Satellite System) receiver. The traveled distance may be expressed in a planar direction (vertical and / or horizontal directions, or latitude and longitude directions). The traveled distance may also be expressed in a three-dimensional direction (height direction). The distance threshold may also be expressed in the same direction as the traveled distance.

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

[0061] The condition for transmitting a measurement report depending on the travel distance (specifically, step S12) may be referred to as a "travel distance condition" below.

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

[0063] Note that UAV 150 may transmit a measurement report when the prohibition time (or time interval) expires, even if the travel distance does not exceed the distance threshold (or if the travel distance is equal to or less than the distance threshold) (No in step S12). For example, when UAV 150 is hovering in the sky, UAV 150 does not move, and therefore the travel distance does not exceed the distance threshold. Even in such a case, the prohibition time (or time interval) may be used to enable UAV 150 to transmit a measurement report at predetermined time intervals (i.e., each time either the prohibition time or the time interval expires).

[0064] (Alternative Example 1 of First Embodiment) Next, an alternative example 1 of the first embodiment will be described. The alternative example 1 of the first embodiment will be described mainly focusing on the differences from the first embodiment.

[0065] Another example 1 of the first embodiment is an example in which the measurement of the travel distance described in the first embodiment (step S11 in FIG. 7 ) is started when an event condition is satisfied. Specifically, the user device (e.g., UAV 150) starts measuring the travel distance when it determines that the event condition is satisfied. This enables, for example, UAV 150 to transmit a measurement report using both the event condition and the travel distance condition.

[0066] 8 is a diagram showing an example of operation in Alternative Example 1 of the first embodiment. In Fig. 8, the same processing parts as those in the first embodiment are denoted by the same reference numerals.

[0067] 8, when the distance threshold is set (step S10), the UAV 150 determines whether the event condition is satisfied in step S20. If the UAV 150 determines that the event condition is satisfied (Yes in step S20), the UAV 150 starts measuring the travel distance (step S11). On the other hand, if the UAV 150 determines that the event condition is not satisfied (No in step S20), the UAV 150 repeats the process until the event condition is satisfied.

[0068] The event used in the event condition may be any event, including an event defined by 3GPP. Such an event may be, for example, the above-described event H1 or event H2. Such an event may also be event A3. Event A3 is an event indicating that the wireless quality of the neighboring cell is higher than the wireless quality of the primary cell.

[0069] The gNB 200 may configure the UAV 150 to measure the travel distance when the event condition is satisfied. In this case, the gNB 200 may perform this configuration by transmitting a measurement configuration including the event condition and a distance threshold to the UAV 150. Alternatively, the gNB 200 may perform this configuration by transmitting a measurement configuration including information indicating that the travel distance is measured when the event condition is satisfied to the UAV 150.

[0070] Note that UAV 150 may make a measurement report when the event condition is satisfied (Yes in step S20). Then, UAV 150 may start measuring the travel distance, with the measurement report being made as the event condition. When UAV 150 makes the measurement report in step S13, the event condition is satisfied, so UAV 150 may start measuring the travel distance again. In this case, UAV 150 will repeatedly measure the travel distance after making the measurement report.

[0071] (Another Example 2 of the First Embodiment) Next, another example 2 of the first embodiment will be described. The description of another 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 UAV 150 transmits a measurement report when both the event condition and the travel distance condition are satisfied. Specifically, the user equipment (e.g., the UAV 150) transmits a measurement report to a base station (e.g., the gNB 200) based on the travel distance (e.g., the travel distance condition) and the event condition. As a result, for example, in another example 2 of the first embodiment, the UAV 150 can transmit a measurement report using both the event condition and the travel distance condition.

[0073] FIG. 9 is a diagram illustrating an example of operation in Alternative Example 2 of the first embodiment.

[0074] As shown in FIG. 9 , in step S30, the gNB 200 configures the UE 100 to use the travel distance condition and the event condition in combination. The gNB 200 may perform this configuration by transmitting a measurement configuration including information indicating that the travel distance condition and the event condition are used in combination to the UAV 150 using an RRC message. Alternatively, the gNB 200 may perform this configuration by transmitting a measurement configuration including a distance threshold and an applicable event to the UAV 150 using an RRC message. The event used in the event condition may be an event defined in 3GPP (for example, event A3, event A5, event H1, or event H2, etc.), as in other example 1 of the first embodiment.

[0075] In step S31, the UAV 150 evaluates the event condition. If the event condition is met, the UAV 150 enters the start (enter) state. On the other hand, if the event condition is not met, the UAV 150 enters the end (leave) state.

[0076] In step S32, the UAV 150 evaluates the travel distance condition. If the travel distance of the UAV 150 is equal to or greater than the distance threshold (or if the UAV 150 exceeds the distance threshold), the UAV 150 enters the start (enter) state. On the other hand, if the travel distance of the UAV 150 is less than the distance threshold (or if the travel distance is equal to or less than the distance threshold), the UAV 150 enters 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 UAV 150 determines whether the two conditions, the event condition and the travel distance condition, are both in the start state. Then, if the two conditions are both in the start state (Yes in step S33), the UAV 150 transmits a measurement report to the gNB 200 (step S34). That is, if the travel distance exceeds the distance threshold and the event condition is met, the UAV 150 transmits a measurement report to the gNB 200. On the other hand, if neither of the two conditions is in the start state (No in step S33), the UAV 150 again proceeds to step S31 and repeats the above-mentioned processing. That is, the UAV 150 will not transmit a measurement report if the travel distance is less than the distance threshold or if the event condition is not met.

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

[0079] In the second embodiment, an example will be described in which the prohibition time (or time interval) is changed (hereinafter, such a change may be referred to as "scaling") according to the movement speed of the UAV 150. The prohibition time refers to the prohibition time (prohibit timer) described in the first embodiment. The time interval refers to the time interval (report interval) for reporting the measurement report described in the first embodiment.

[0080] Specifically, first, the user equipment (e.g., UAV 150) determines a timer value (e.g., a prohibition time or a time interval) according to the moving speed of the user equipment. Second, the user equipment transmits a measurement report to the base station (e.g., gNB 200) when the count value counted by the timer reaches the timer value.

[0081] As a result, for example, the UAV 150 can transmit measurement reports according to the moving speed, and therefore the number of measurement reports to be transmitted can be controlled 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 prohibition time (or time interval) can be scaled, for example, as follows: That is, when the movement speed of the UAV 150 is equal to or greater than the speed threshold (i.e., when the UAV 150 is moving at high speed), the UAV 150 determines the timer value to be less than the time threshold. Also, for example, when the movement speed of the UAV 150 is less than the speed threshold (i.e., when the UAV 150 is moving at low speed), the UAV 150 determines the timer value to be equal to or greater than the time threshold. With such scaling, when the movement speed of the UAV 150 is equal to or greater than the speed threshold (i.e., when the UAV 150 is moving at high speed), the timer value becomes less than the time threshold, making it possible to appropriately suppress the number of measurement reports compared to when the prohibition time or time interval is constant. Furthermore, such scaling ensures that when the movement speed of UAV 150 is below the speed threshold (i.e., when UAV 150 is moving slowly), the timer value is greater than or equal to the time threshold, allowing UAV 150 to properly transmit measurement reports even when UAV 150 is hovering.

[0083] (Example of Operation According to Second Embodiment) FIG. 10 is a diagram showing an example of operation according to the second embodiment.

[0084] 10, in step S40, the gNB 200 sets a setting timer value to the UAV 150. The setting timer value is represented by either a prohibition time (prohibit timer) or a time interval for reporting a measurement report (report interval). The gNB 200 may set the setting timer value by transmitting a measurement configuration including the setting timer value to the UAV 150 using an RRC message.

[0085] In step S41, gNB200 sets a scaling value to UAV105. gNB200 may set the scaling value by transmitting a measurement configuration including the scaling value to UAV150 using an RRC message.

[0086] The order of steps S40 and S41 may be reversed. Steps S40 and S41 may be combined into one measurement configuration. When the two configurations are combined into one, the gNB 200 may transmit one measurement configuration including the timer value and the scaling value to the UAV 150 using one RRC message.

[0087] In step S42, the UAV 150 determines a timer value. For example, the UAV 150 determines the timer value by scaling the set timer value with a scaling value corresponding to the movement speed. Specifically, the UAV 150 may determine the timer value as follows.

[0088] First, UAV 150 may multiply the scaling value by the movement speed of UAV 150 and divide the set timer value by the multiplied value ([set timer value] ÷ {[scaling value] × [movement speed of UAV 150]}) to determine the timer value. The faster the movement speed of UAV 150, the smaller the timer value. The timer value is determined according to the movement speed. UAV 150 may determine the timer value by measuring its own movement speed and substituting each value into the above formula. The method of measuring the movement speed may be the same as in the first embodiment.

[0089] Second, the UAV 150 may determine the timer value as a value obtained by multiplying the set timer value by a scaling value for each movement state of the UAV 150 ([set timer value] x [scaling value for each movement state of the UAV 150]). The movement state of the UAV 150 represents a state classified according to the movement speed of the UAV 150. For example, the movement state of the UAV 150 may be a "stationary state" when the movement speed of the UAV 150 is between "0" and less than a first speed threshold, a "low-speed movement state" when the movement speed of the UAV 150 is equal to or greater than the first speed threshold and equal to or less than a second speed threshold (first speed threshold < second speed threshold), or a "high-speed movement state" when the movement speed of the UAV 150 exceeds the second speed threshold. Also, for example, the scaling value set by the gNB 200 may be "1" for a "stationary state", "0.5" for a "low-speed movement state", or "0.2" for a "high-speed movement state". The UAV 150 measures its own moving speed, checks the moving state according to the moving speed, and determines the timer value using a scaling value according to the moving state. The method of measuring the moving speed may be the same as that of the first embodiment.

[0090] In step S43, the UAV 150 starts counting by a timer in response to transmitting the measurement report. The UAV 150 may start counting by a timer at a predetermined timing.

[0091] In step S44, the UAV 150 determines whether the count value of the timer has reached the timer value (i.e., whether the timer value has expired).

[0092] When the count value reaches the timer value (Yes in step S45), in step S46, UAV150 transmits a measurement report to gNB200. That is, UAV150 transmits the measurement report in response to the expiration of the timer.

[0093] On the other hand, if the count value does not reach the timer value (No in step S45), the UAV 150 waits until the count value reaches the timer value (No in step S45). In other words, the UAV 150 waits to transmit the measurement report until the timer expires.

[0094] If the movement state of UAV 150 changes while the count value is being counted (i.e., while the timer is running), UAV 150 may change the timer value. If the timer value is changed, the count value of the timer may be restarted without being reset. Alternatively, if the timer value is changed, the count value may be reset, assuming that the timer has expired (or the count value has reached the timer value).

[0095] [Other Embodiments] The above-described operational flows are not limited to being implemented independently, but can be implemented by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow. In each flow, it is not necessary to execute all steps, and only some steps may be executed. In the above-described embodiments and examples, an example in which the base station is an NR base station (gNB) has been described, but the base station may also be an LTE base station (eNB) or a 6G base station. Furthermore, the base station may be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may be a DU of the IAB node. Furthermore, the UE 100 may be an MT (Mobile Termination) of the IAB node.

[0096] Also, the term "network node" primarily refers to a base station, but may also refer to a device in the core network or part of a base station (CU, DU, or RU).

[0097] A program may be provided that causes a computer to execute each process performed by the UE 100 or the gNB 200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. Furthermore, circuits that execute each process performed by the UE 100 or the gNB 200 may be integrated, and at least a portion of the UE 100 or the gNB 200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0098] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "depending only on" and "depending at least in part on." The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Additionally, the term "or," as used in this disclosure, is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0099] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes can be made within the scope of the gist. Furthermore, it is also possible to combine all or part of each embodiment, each operation, each process, and each step within the scope of consistent combinations.

[0100] This application claims priority to U.S. Provisional Application No. 63 / 410,362 (filed September 27, 2022), the entire contents of which are incorporated herein by reference.

[0101] (Supplementary Note) (Supplementary Note 1) A communication control method in a mobile communication system, comprising: 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 according to a moving distance of the user equipment.

[0102] (Supplementary Note 2) The communication control method according to Supplementary Note 1, wherein the transmitting step includes a step of the user equipment transmitting the measurement report to the network node when the movement distance exceeds a distance threshold.

[0103] (Supplementary Note 3) The communication control method according to Supplementary Note 1 or Supplementary Note 2, wherein the step of transmitting the measurement report to the network node when the moving distance exceeds the distance threshold includes a step of the user equipment transmitting the measurement report to the network node at predetermined time intervals when the moving distance is equal to or less than the distance threshold.

[0104] (Supplementary Note 4) The communication control method according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the predetermined time is either a prohibition time or a time interval for reporting the measurement report.

[0105] (Supplementary Note 5) The communication control method according to any one of Supplementary Notes 1 to 4, further comprising the step of the network node setting the distance threshold in the user equipment.

[0106] (Supplementary Note 6) The communication control method according to any one of Supplementary Notes 1 to 5, wherein the transmitting step includes a step of starting measurement of the travel distance when the user device determines that an event condition is satisfied.

[0107] (Supplementary Note 7) The communication control method according to any one of Supplementary Notes 1 to 6, wherein the transmitting step includes a step in which the user equipment transmits the measurement report to the network node based on the moving distance and an event condition.

[0108] (Supplementary Note 8) The communication control method according to any one of Supplementary Notes 1 to 7, wherein the step of transmitting the measurement report to the network node based on the moving distance and the event condition includes a step of the user equipment transmitting the measurement report to the network node when the moving distance exceeds a distance threshold and the event condition is satisfied.

[0109] (Supplementary Note 9) The communication control method according to any one of Supplementary Notes 1 to 8, further comprising the step of: the network node configuring the user equipment to use the travel distance and the event condition in combination.

[0110] (Supplementary Note 10) A communication control method in a mobile communication system, comprising: a step in which a user equipment determines a timer value according to a moving speed of the user equipment; and a step in which the user equipment transmits a measurement report to a network node when a count value counted by a timer reaches the timer value.

[0111] (Supplementary Note 11) The communication control method according to Supplementary Note 10, wherein the determining step includes a step in which the user device sets the timer value to be less than a time threshold when the moving speed is equal to or greater than a speed threshold, and sets the timer value to be equal to or greater than the time threshold when the moving speed is less than the speed threshold.

[0112] (Supplementary Note 12) The communication control method according to Supplementary Note 10 or Supplementary Note 11, further comprising a step in which the network node sets a set timer value and a scaling value in the user equipment, and the determining step includes a step in which the user equipment determines, as the timer value, a value obtained by scaling the set timer value by the scaling value according to the moving speed.

Claims

1. A communication control method in a mobile communication system, comprising: A user equipment located at an altitude equal to or higher than a predetermined threshold transmits a measurement report to a network node according to a moving distance of the user equipment. Communications control method.

2. The transmitting includes the user equipment transmitting the measurement report to the network node when the traveled distance exceeds a distance threshold. The communication control method according to claim 1.

3. Transmitting the measurement report to the network node when the moving distance exceeds the distance threshold includes transmitting the measurement report to the network node at predetermined time intervals when the moving distance is equal to or less than the distance threshold by the user equipment. The communication control method according to claim 2.

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

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

6. The transmitting step includes starting measurement of the travel distance when the user device determines that an event condition is satisfied. The communication control method according to claim 1.

7. The sending step includes the user equipment sending the measurement report to the network node based on the travel distance and an event condition. The communication control method according to claim 1.

8. Transmitting the measurement report to the network node based on the travel distance and the event condition includes the user equipment transmitting the measurement report to the network node when the travel distance exceeds a distance threshold and the event condition is satisfied. The communication control method according to claim 7.

9. The network node further includes setting the user device to use the travel distance and the event condition in combination. The communication control method according to claim 7.

10. A communication control method in a mobile communication system, comprising: A user device determines a timer value according to a moving speed of the user device; The user equipment transmits a measurement report to a network node in response to a count value counted by a timer reaching the timer value. Communications control method.

11. The determining step includes the user device setting the timer value to be less than a time threshold when the moving speed is equal to or greater than a speed threshold, and setting the timer value to be equal to or greater than the time threshold when the moving speed is less than the speed threshold. The communication control method according to claim 10.

12. The network node further comprises configuring timer values ​​and scaling values ​​in the user equipment; The determining step includes determining, by the user device, as the timer value, a value obtained by scaling the set timer value by the scaling value according to the moving speed. The communication control method according to claim 11.

13. A user equipment in a mobile communication system, comprising: A transmitter that transmits a measurement report to a network node according to a moving distance of the user equipment when the user equipment is located at an altitude equal to or higher than a predetermined threshold. User equipment.

14. A user equipment in a mobile communication system, comprising: A control unit that determines a timer value in accordance with a moving speed of the user device; a transmitter that transmits a measurement report to a network node when a count value counted by the timer reaches the timer value. User equipment.

Images