Communication terminal, distance measurement method and program

Abstract

To measure a distance between a communication terminal that communicates with a base station via a relay device and the relay device.SOLUTION: A communication terminal includes: a loss identification unit 143 that identifies a relay propagation loss of a relay reference signal received from a base station through a relay device on the basis of relay reception power of the relay reference signal received from the base station through the relay device, and identifies a direct propagation loss of a direct reference signal received from the base station without going through the relay device on the basis of direct reception power of the direct reference signal received from the base station without going through the relay device; and an estimation unit 144 that estimates a relayed propagation loss as a propagation loss from the relay device to the communication terminal on the basis of a gain, a relay propagation loss and a direct propagation loss when the relay device receives the relay reference signal from the base station and transmits the relay reference signal to the communication terminal, and estimates a first distance from the communication terminal to the relay device on the basis of the relayed propagation loss.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a communication terminal, a distance measuring method, and a program. [Background technology]

[0002] Methods for measuring the distance from a wireless terminal to a base station have been proposed. For example, Patent Document 1 describes measuring the distance between a wireless terminal and a base station by observing the reception timing of a pilot signal that arrives from the base station to the wireless terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-108903 A Summary of the Invention [Problem to be solved by the invention]

[0004] A wireless terminal may communicate with a base station via a relay device. The relay device relays a pilot signal transmitted from a base station and transmits the pilot signal to the wireless terminal, but the relay device itself cannot transmit a pilot signal to the wireless terminal. For this reason, the technology described in Patent Document 1 has a problem in that it is not possible to measure the distance between the wireless terminal and the relay device.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to make it possible to measure the distance between a communication terminal that communicates with a base station via a relay device and the relay device. [Means for solving the problem]

[0006] A first aspect of the present invention is a communication terminal that communicates with a base station via a relay device, and includes a power identifying unit that identifies a relay reception power, which is the power of a relay reference signal received from the base station via the relay device, and identifies a direct reception power, which is the power of a direct reference signal received from the base station without passing through the relay device; a loss identifying unit that identifies a relay propagation loss of the relay reference signal received from the base station via the relay device based on the relay reception power identified by the power identifying unit, and identifies a direct propagation loss of the direct reference signal received from the base station without passing through the relay device based on the direct reception power identified by the power identifying unit; and an estimation unit that estimates a post-relay propagation loss, which is the propagation loss from the relay device to the communication terminal, based on a gain when the relay device receives the relay reference signal from the base station and transmits the relay reference signal to the communication terminal, the relay propagation loss, and the direct propagation loss, and estimates a first distance from the communication terminal to the relay device based on the post-relay propagation loss.

[0007] The estimation unit may estimate the post-relay path loss by subtracting the direct path loss from the relay path loss and adding the gain. The communication terminal may further include a speed determination unit that determines a relative speed between the communication terminal and the relay device and a direction in which the relay device moves as seen from the communication terminal, and a determination unit that determines an angular velocity at which the relay device moves as seen from the communication terminal based on the relative speed, the first distance, and the direction in which the relay device moves as seen from the communication terminal, and determines a frequency at which the relay device sweeps a beam for communication with the communication terminal based on the determined angular velocity.

[0008] The determination unit may determine a higher frequency as the angular velocity increases. The communication terminal may further include a transmission control unit configured to transmit information indicating the frequency determined by the determination unit to the base station. The relay device may receive the relay reference signal from the base station in a millimeter wave band, and the power specifying unit may receive the relay reference signal from the relay device in a terahertz wave band.

[0009] A distance measurement method of a second aspect of the present invention includes the steps of: executing, by a communication terminal, identifying a relayed received power, which is the power of a relayed reference signal received from a base station via a relay device, and identifying a direct received power, which is the power of a direct reference signal received from the base station without passing through the relay device; identifying a relay propagation loss of the relayed reference signal received from the base station via the relay device based on the identified relayed received power, and identifying a direct propagation loss of the direct reference signal received from the base station without passing through the relay device based on the identified direct received power; estimating a post-relay propagation loss, which is the propagation loss from the relay device to the communication terminal, based on a gain when the relay device receives the relay reference signal from the base station and transmits the relayed reference signal to the communication terminal, the relay propagation loss, and the direct propagation loss, and estimating a first distance from the communication terminal to the relay device based on the post-relay propagation loss.

[0010] A third aspect of the program of the present invention causes a communication terminal to execute the steps of: identifying a relayed reception power, which is the power of a relayed reference signal received from a base station via a relay device, and identifying a direct reception power, which is the power of a direct reference signal received from the base station without passing through the relay device; identifying a relay propagation loss of the relayed reference signal received from the base station via the relay device based on the identified relay reception power, and identifying a direct propagation loss of the direct reference signal received from the base station without passing through the relay device based on the identified direct reception power; estimating a post-relay propagation loss, which is the propagation loss from the relay device to the communication terminal, based on a gain when the relay device receives the relay reference signal from the base station and transmits the relay reference signal to the communication terminal, the relay propagation loss, and the direct propagation loss, and estimating a first distance from the communication terminal to the relay device based on the post-relay propagation loss. Effect of the Invention

[0011] According to the present invention, it is possible to measure the distance between a communication terminal that communicates with a base station via a relay device and the relay device. [Brief description of the drawings]

[0012] [Figure 1] 1 shows an overview of a distance estimation system according to an embodiment. [Diagram 2] 1 shows the configuration of a relay device. [Diagram 3] This shows how the first communication control unit sweeps the beam. [Figure 4] 2 shows the configuration of a communication terminal. [Diagram 5] 10 is a flowchart showing a processing procedure in which a communication terminal determines a frequency at which a relay device sweeps a beam for communicating with the communication terminal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Outline of distance estimation system] 1 shows an overview of a distance estimation system S according to the present embodiment. The distance estimation system S includes a communication terminal 100, a base station 200, and a relay device 300. The communication terminal 100 is, for example, a smartphone. The communication terminal 100 communicates with the base station 200 through a relay communication path R1 that passes through the relay device 300. The relay communication path R1 includes an intermediate communication path R1a from the base station 200 to the relay device 300, and a post-relay communication path R1b from the relay device 300 to the communication terminal 100. The communication terminal 100 also communicates with the base station 200 through a direct communication path R2 that does not pass through the relay device 300.

[0014] The base station 200 communicates with the communication terminal 100 via a relay communication path R1 or a direct communication path R2. The distance between the base station 200 and the relay device 300 is, for example, several hundred meters. The communication terminal 100 is in the vicinity of the relay device 300, and the distance between the base station 200 and the communication terminal 100 is approximately the same as the distance between the base station 200 and the relay device 300, for example, several hundred meters. The base station 200 communicates with the relay device 300 in the millimeter wave band. The wavelength of the millimeter wave is 1 millimeter to 10 millimeters. The base station 200 communicates with the communication terminal 100 in the terahertz wave band or the millimeter wave band. The wavelength of the terahertz wave is 100 microns to 1 millimeter.

[0015] The relay device 300 relays communication between the communication terminal 100 and the base station 200. The relay device 300 relays communication between the communication terminal 100 and the base station 200, for example, when worn by a user. A plurality of relay devices 300 may relay communication between the communication terminal 100 and the base station 200, respectively. The relay device 300 communicates with the base station 200 in the millimeter wave band. For example, the relay device 300 receives a relay reference signal from the base station 200 in the millimeter wave band. The relay reference signal is a signal that the relay device 300 receives from the base station 200 in order to measure communication quality such as a propagation loss when receiving a signal from the base station 200, and is, for example, an SSB (Synchronization Signal Block) transmitted from the base station 200. The relay device 300 communicates with the communication terminal 100 in the terahertz wave band. The distance between the relay device 300 and the communication terminal 100 is, for example, several tens of centimeters.

[0016] A method for the communication terminal 100 to estimate the distance to the relay device 300 will be described below. The distance between the communication terminal 100 and the relay device 300 is estimated in order to determine a parameter (e.g., a sweep frequency) for the relay device 300 to sweep a beam for communication with the communication terminal 100. The communication terminal 100 specifies the power of a relay reference signal received from the base station 200 via the relay device 300 (hereinafter also referred to as relay reception power). Based on the specified relay reception power, the communication terminal 100 determines the propagation loss (hereinafter also referred to as relay propagation loss) PL (R1) Identify.

[0017] The communication terminal 100 identifies the power of a direct reference signal received from the base station 200 without passing through the relay device 300 (hereinafter also referred to as direct reception power). The direct reference signal is a signal that the communication terminal 100 receives from the base station 200 in order to measure communication quality such as a propagation loss when receiving a signal from the base station 200, and is, for example, an SSB. The communication terminal 100 determines the propagation loss (hereinafter also referred to as direct propagation loss) PL (R2) Identify.

[0018] The communication terminal 100 is configured to receive a gain G Rep is stored in advance in the storage unit. Rep is a constant indicating the relationship between the reception power at which the relay device 300 receives the relay reference signal transmitted by the base station 200 and the transmission power at which the relay device 300 transmits this relay reference signal to the communication terminal 100.

[0019] The communication terminal 100 determines the determined relay propagation loss PL (R1) and the direct path loss PL (R2) and the obtained gain G Rep Based on this, the propagation loss in the post-relay communication path R1b from the relay device 300 to the communication terminal 100 (hereinafter also referred to as the post-relay propagation loss) PL (R1b) The communication terminal 100 estimates the estimated post-relay path loss PL (R1b) Based on this, the first distance d from the communication terminal 100 to the relay device 300 is calculated. (R1b) In this manner, the communication terminal 100 estimates the first distance d between the communication terminal 100 and the relay device 300 without having to newly install a sensor for measuring the distance in the communication terminal 100. (R1b) can be estimated.

[0020] [Configuration of relay device 300] 2 shows a configuration of the relay device 300. The relay device 300 includes an acceleration sensor 31, a first communication unit 32, a second communication unit 33, a storage unit 34, and a control unit 35. The control unit 35 includes a measurement unit 351, a first communication control unit 352, and a second communication control unit 353.

[0021] The acceleration sensor 31 measures the acceleration and the direction of acceleration of the relay device 300. The acceleration sensor 31 inputs the measured acceleration and the direction of acceleration to the measurement unit 351.

[0022] The first communication unit 32 is a wireless communication module for communicating with the communication terminal 100. The first communication unit 32 communicates with the communication terminal 100 in the terahertz wave band. The second communication unit 33 is a wireless communication module for communicating with the base station 200. The second communication unit 33 communicates with the base station 200 in the millimeter wave band.

[0023] The storage unit 34 is a storage medium including a read only memory (ROM) and a random access memory (RAM), etc. The storage unit 34 stores a program that the control unit 35 executes.

[0024] The control unit 35 is, for example, a CPU (Central Processing Unit). The control unit 35 executes a program stored in the storage unit 34 to function as a measurement unit 351, a first communication control unit 352, and a second communication control unit 353.

[0025] The measurement unit 351 determines the moving speed and the moving direction of the relaying device 300 based on the acceleration and the direction of acceleration of the relaying device 300. The measurement unit 351 outputs information indicating the determined moving speed and the moving direction of the relaying device 300 to the first communication control unit 352.

[0026] The first communication control unit 352 communicates with the communication terminal 100 via the first communication unit 32. The first communication control unit 352 receives various information from the communication terminal 100. For example, the first communication control unit 352 receives information from the communication terminal 100 instructing the frequency of sweeping a beam for communicating with the communication terminal 100.

[0027] The first communication control unit 352 transmits information that the second communication control unit 353 receives from the base station 200 to the communication terminal 100. For example, when the second communication control unit 353 receives a relay reference signal, the first communication control unit 352 transmits the relay reference signal to the communication terminal 100. The relay reference signal is transmitted from the base station 200 to the communication terminal 100 in order to measure a relay propagation loss when the communication terminal 100 receives a signal from the base station 200 via the relay device 300.

[0028] The first communication control unit 352 transmits information indicating the state of the relay device 300 to the communication terminal 100. For example, the first communication control unit 352 transmits information indicating the moving speed identified by the measurement unit 351 and the moving direction of the relay device 300 to the communication terminal 100.

[0029] The first communication control unit 352 controls the first communication unit 32 to sweep a beam for communicating with the communication terminal 100. Since the communication terminal 100 and the relay device 300 each move, their relative positional relationship changes successively. The first communication control unit 352 sweeps a beam for communicating with the communication terminal 100, so that the communication between the communication terminal 100 and the relay device 300 is not interrupted even if the relative position of the communication terminal 100 changes.

[0030] Fig. 3 shows how the first communication control unit 352 sweeps the beam. The multiple dashed lines in Fig. 3 indicate the directions of the beam at multiple timings. The first communication control unit 352 sweeps the beam in a predetermined range around the communication terminal 100, so that the communication terminal 100 does not move out of the beam sweep range even if the relative position of the communication terminal 100 changes. The predetermined range is, for example, the maximum range within which the communication terminal 100 is expected to move while being held by a user.

[0031] In the example of this specification, the first communication control unit 352 receives information instructing the frequency at which the beam is swept from the communication terminal 100. The first communication control unit 352 sweeps the beam at the received frequency. The first communication control unit 352 may acquire from the communication terminal 100 the angular velocity at which the relay device 300 moves as viewed from the communication terminal 100, and determine the frequency at which the beam is swept based on the acquired angular velocity. The first communication control unit 352 may sweep the beam at the determined frequency.

[0032] 2 communicates with the base station 200 via the second communication unit 33. The second communication control unit 353 receives various information from the base station 200. For example, the second communication control unit 353 receives a relay reference signal from the base station 200. The second communication control unit 353 outputs the received information to the first communication control unit 352.

[0033] [Configuration of communication terminal 100] 4 shows the configuration of the communication terminal 100. The communication terminal 100 includes an acceleration sensor 11, a communication unit 12, a storage unit 13, and a control unit 14. The control unit 14 includes a speed specifying unit 141, a power specifying unit 142, a loss specifying unit 143, an estimation unit 144, a determination unit 145, and a transmission control unit 146.

[0034] Acceleration sensor 11 measures the acceleration and the direction of acceleration of communication terminal 100. Acceleration sensor 11 inputs the measured acceleration and the direction of acceleration to speed identification unit 141.

[0035] The communication unit 12 is a wireless communication module for communicating with the base station 200 or the relay device 300. For example, the communication unit 12 communicates with the base station 200 in the millimeter wave band. The communication unit 12 communicates with the relay device 300 in the terahertz wave band. For example, the communication unit 12 receives a relay reference signal from the relay device 300 in the terahertz wave band.

[0036] The storage unit 13 is a storage medium including a ROM, a RAM, and the like. The storage unit 13 stores a program executed by the control unit 14. For example, the storage unit 13 stores a gain G Rep The gain G Rep is a constant indicating the relationship between the received power at which the relay device 300 receives the relay reference signal transmitted by the base station 200 and the transmission power at which the relay device 300 transmits the relay reference signal to the communication terminal 100. The storage unit 13 stores in advance the transmission power at which the base station 200 transmits the relay reference signal to the communication terminal 100 via the relay device 300. The storage unit 13 stores in advance the transmission power at which the base station 200 transmits the direct reference signal to the communication terminal 100.

[0037] The control unit 14 is, for example, a CPU. The control unit 14 executes a program stored in the storage unit 13 to function as a speed specifying unit 141, a power specifying unit 142, a loss specifying unit 143, an estimation unit 144, a determination unit 145, and a transmission control unit 146.

[0038] The speed identifying unit 141 identifies the relative speed between the communication terminal 100 and the relay device 300, and the direction in which the relay device 300 moves as viewed from the communication terminal 100. The speed identifying unit 141 acquires the acceleration and the direction in which the communication terminal 100 accelerates from the acceleration sensor 11. The speed identifying unit 141 identifies the moving speed and the moving direction of the communication terminal 100 based on the acceleration and the direction in which the communication terminal 100 accelerates.

[0039] The speed specifying unit 141 communicates with the relay device 300 via the communication unit 12. The speed specifying unit 141 acquires the moving speed and the direction of the relay device 300 from the relay device 300. The speed specifying unit 141 specifies the relative speed between the communication terminal 100 and the relay device 300 based on the moving speed and the direction of the communication terminal 100, the moving speed and the direction of the relay device 300. At this time, the speed specifying unit 141 specifies not only the relative speed but also the direction of the relay device 300 moving relatively as seen from the communication terminal 100. The speed specifying unit 141 outputs information indicating the specified relative speed and the direction of the relay device 300 moving relatively as seen from the communication terminal 100 to the determination unit 145.

[0040] [Determining received power] The power specifying unit 142 communicates with the base station 200 and the relay device 300 via the communication unit 12. The power specifying unit 142 receives a relay reference signal from the base station 200 on a relay communication path R1 that passes through the relay device 300. The power specifying unit 142 specifies relay reception power, which is the power of the received relay reference signal. The power specifying unit 142 receives a direct reference signal from the base station 200 on a direct communication path R2 that does not pass through the relay device 300. The direct reference signal is transmitted from the base station 200 to measure a propagation loss when a signal is transmitted from the base station 200 to the communication terminal 100 on the direct communication path R2 that does not pass through the relay device 300. The power specifying unit 142 specifies direct reception power, which is the power of the received direct reference signal. The power specifying unit 142 outputs information indicating the specified relay reception power and direct reception power to the loss specifying unit 143.

[0041] [Determining propagation loss] The loss specifying unit 143 calculates the relay propagation loss PL of the relay reference signal received from the base station 200 via the relay device 300 based on the relay reception power specified by the power specifying unit 142. (R1)First, the loss identifying unit 143 reads out the transmission power of the relay reference signal transmitted by the base station 200 from the storage unit 13. The loss identifying unit 143 calculates the ratio between the relay reception power identified by the power identifying unit 142 and the transmission power of the relay reference signal, thereby determining the relay propagation loss PL (R1) Identify.

[0042] The loss specifying unit 143 calculates a direct path loss PL of the direct reference signal received from the base station 200 without passing through the relay device 300 based on the direct reception power specified by the power specifying unit 142. (R2) First, the loss identifying unit 143 reads out the transmission power of the direct reference signal transmitted by the base station 200 from the storage unit 13. The loss identifying unit 143 calculates the ratio between the direct reception power identified by the power identifying unit 142 and the transmission power of the direct reference signal, thereby determining the direct path loss PL (R2) The loss determination unit 143 determines the determined relay propagation loss PL (R1) and direct propagation loss PL (R2) The estimation unit 144 outputs information indicating this.

[0043] [First distance d (R1b) Estimates of The estimation unit 144 estimates the gain G Rep and the relay propagation loss PL (R1) and the direct path loss PL (R2) Based on this, a post-relay path loss PL (R1b) For example, the estimation unit 144 estimates the relay path loss PL (R1) Direct propagation loss PL (R2) and the gain G Rep By adding (R1b) Estimate.

[0044] First, the estimation unit 144 estimates the gain G Rep The post-relay path loss PL on the post-relay communication path R1b from the relay device 300 to the communication terminal 100 is read.(R1b) is represented by the following formula: PL (R1b) =PL (R1) -PL (R1a) +G Rep ...(1). In formula (1), PL (R1a) is the propagation loss of the relay reference signal on the intermediate communication path R1a from the base station 200 to the relay device 300 (hereinafter, also referred to as intermediate propagation loss).

[0045] Since the distance of the direct communication route R2 is sufficiently larger than the distance of the relayed communication route R1b, PL (R2) ≒ PL (R1a) ...(2) can be approximated. Applying equation (2) to equation (1), PL (R1b) ≒ PL (R1) -PL (R2) +G Rep ...(3). The estimation unit 144 calculates the post-relay path loss PL (R1b) Estimate.

[0046] The estimation unit 144 estimates the post-relay path loss PL (R1b) Based on this, the first distance d from the communication terminal 100 to the relay device 300 is calculated. (R1b) The first distance d (R1b) is the following formula: (R1b) =FSPL -1 (PL (R1b) )...(4). In equation (4), FSPL is a function for calculating the free space propagation loss. The estimation unit 144 calculates the first distance d (R1b) The estimation unit 144 estimates the estimated first distance d (R1b) The determination unit 145 outputs information indicating this.

[0047] [Determining the frequency at which the beam is swept] The determination unit 145 determines the frequency at which the relay device 300 sweeps a beam for communication with the communication terminal 100. More specifically, the determination unit 145 determines the frequency at which the relay device 300 sweeps a beam for communication with the communication terminal 100 based on the relative speed identified by the speed identification unit 141, the direction in which the relay device 300 moves as seen from the communication terminal 100, and the first distance d (R1b)と、Based on this, the angular velocity φ at which the relay device 300 moves as seen from the communication terminal 100 is identified. Based on the identified angular velocity φ, the determination unit 145 determines the frequency at which the relay device 300 sweeps a beam for communicating with the communication terminal 100. At this time, the determination unit 145 determines the frequency at which the beam is swept to be higher as the angular velocity φ is larger.

[0048] The determination unit 145 determines whether the estimation unit 144 determines the first distance d (R1b) For example, the determination unit 145 may determine the frequency of sweeping the beam every time the estimation unit 144 estimates a plurality of first distances d (R1b) After estimating, multiple first distances d (R1b) The statistic may be, for example, an average value. The determining unit 145 may calculate the statistic of the calculated first distance d (R1b) The frequency of sweeping the beam may be determined based on the statistics of the above. The determination unit 145 outputs information indicating the determined frequency to the transmission control unit 146.

[0049] [Transmission of information to base station 200] The transmission control unit 146 transmits various information to the base station 200 via the communication unit 12. For example, the transmission control unit 146 transmits information indicating the frequency determined by the determination unit 145 to the relay device 300. The transmission control unit 146 transmits information indicating the frequency determined by the determination unit 145 to the base station 200 in addition to the relay device 300. In this manner, the transmission control unit 146 notifies the base station 200 of the frequency at which the relay device 300 sweeps a beam for communicating with the communication terminal 100, thereby suppressing the occurrence of overhead caused by the timing at which the base station 200 transmits various information to the relay device 300 overlapping with the timing at which the relay device 300 sweeps a beam.

[0050] [Procedure for determining the frequency at which the beam is swept] 5 is a flowchart showing a processing procedure in which the communication terminal 100 determines a frequency at which the relay device 300 sweeps a beam for communicating with the communication terminal 100. This processing procedure is started during communication between the communication terminal 100 and the relay device 300, for example.

[0051] First, the speed identifying unit 141 identifies the relative speed between the communication terminal 100 and the relay device 300 (S101). The power identifying unit 142 receives a relay reference signal from the base station 200 via the relay device 300, and identifies the relay received power, which is the power of the received relay reference signal. The power identifying unit 142 receives a direct reference signal from the base station 200 via a direct communication path R2 that does not pass through the relay device 300, and identifies the direct received power, which is the power of the received direct reference signal (S102).

[0052] The loss specifying unit 143 calculates the relay propagation loss PL of the relay reference signal received from the base station 200 via the relay device 300 based on the relay reception power specified by the power specifying unit 142. (R1) Based on the direct reception power specified by the power specifying unit 142, the loss specifying unit 143 specifies the direct path loss PL (R2) (S103).

[0053] The estimation unit 144 estimates the gain G Rep The estimation unit 144 reads out the relay path loss PL (R1) Direct propagation loss PL (R2) and the gain G Rep By adding (R1b) is estimated (S104).

[0054] The estimation unit 144 estimates the post-relay path loss PL (R1b) Based on this, the first distance d from the communication terminal 100 to the relay device 300 is calculated. (R1b)The determination unit 145 estimates the first distance d (R1b) Based on this, the angular velocity φ at which the relay device 300 moves as viewed from the communication terminal 100 is determined (S106).

[0055] The determination unit 145 determines the frequency at which the relay device 300 sweeps the beam for communicating with the communication terminal 100 based on the identified angular velocity φ (S107). The transmission control unit 146 transmits information indicating the frequency determined by the determination unit 145 to the relay device 300 and the base station 200 (S108), and ends the process.

[0056] [Effects of the communication terminal 100 of this embodiment] In the communication terminal 100 of the present embodiment, the estimation unit 144 estimates the first distance d between the communication terminal 100 and the relay device 300 without newly installing a sensor for measuring the distance to the relay device 300 in the communication terminal 100. (R1b) The estimation unit 144 can estimate the first distance d (R1b) Therefore, the first distance d (R1b) By repeating the estimation of this first distance d (R1b) The frequency of beam sweeping can be adjusted at an appropriate timing according to changes in the light intensity.

[0057] Furthermore, this invention will make it possible to contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote industry, innovation and infrastructure."

[0058] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0059] 11 Acceleration Sensor 12 Communications Department 13 Storage section 14 Control section 31 Acceleration Sensor 32 First Communications Department 33 2nd Communications Department 34 Storage section 35 Control section 100 Communication terminal 141 Speed ​​identification part 142 Electricity Specification Department 143 Loss Identification Department 144 Estimation Department 145 Decision Section 146 Transmission control section 200 base stations 300 Intermediate Devices 351 Measuring section 352 First communication control unit 353 Second Communication Control Unit

Claims

1. A communication terminal that communicates with a base station via a relay device, a power determination unit that determines a relayed received power, which is the power of a relayed reference signal received from the base station via the relay device, and determines a direct received power, which is the power of a direct reference signal received from the base station without passing through the relay device; a loss identifying unit that identifies a relay path loss of the relay reference signal received from the base station via the relay device based on the relay reception power identified by the power identifying unit, and identifies a direct path loss of the direct reference signal received from the base station without passing through the relay device based on the direct reception power identified by the power identifying unit; an estimation unit that estimates a post-relay path loss, which is a path loss from the relay device to the communication terminal, based on a gain when the relay device receives the relay reference signal from the base station and transmits the relay reference signal to the communication terminal, the relay path loss, and the direct path loss, and estimates a first distance from the communication terminal to the relay device based on the post-relay path loss; A communication terminal comprising:

2. The estimation unit estimates the post-relay path loss by subtracting the direct path loss from the relay path loss and adding the gain. The communication terminal according to claim 1.

3. a speed determination unit that determines a relative speed between the communication terminal and the relay device and a direction in which the relay device moves as viewed from the communication terminal; a determination unit that determines an angular velocity at which the relay device moves as viewed from the communication terminal, based on the relative velocity, the first distance, and a direction in which the relay device moves as viewed from the communication terminal, and determines a frequency at which the relay device sweeps a beam for communication with the communication terminal, based on the determined angular velocity; The communication terminal according to claim 1 or 2, further comprising:

4. The determination unit determines a higher frequency as the angular velocity increases. The communication terminal according to claim 3.

5. a transmission control unit that transmits information indicating the frequency determined by the determination unit to the base station, The communication terminal according to claim 3.

6. the relay device receives the relay reference signal from the base station in a millimeter wave band; The power identifying unit receives the relay reference signal from the relay device in a terahertz wave band.

3. A communication terminal according to claim 1 or 2.

7. The communication terminal executes determining a relayed received power, which is the power of a relayed reference signal received from a base station via a relay device, and determining a direct received power, which is the power of a direct reference signal received from the base station without passing through the relay device; determining a relay path loss of the relay reference signal received from the base station via the relay device based on the determined relay reception power, and determining a direct path loss of the direct reference signal received from the base station without passing through the relay device based on the determined direct reception power; estimating a post-relay path loss, which is a path loss from the relay device to the communication terminal, based on a gain when the relay device receives the relay reference signal from the base station and transmits the relay reference signal to the communication terminal, the relay path loss, and the direct path loss, and estimating a first distance from the communication terminal to the relay device based on the post-relay path loss; A distance measuring method comprising:

8. In the communication terminal, determining a relayed received power, which is the power of a relayed reference signal received from a base station via a relay device, and determining a direct received power, which is the power of a direct reference signal received from the base station without passing through the relay device; determining a relay path loss of the relay reference signal received from the base station via the relay device based on the determined relay reception power, and determining a direct path loss of the direct reference signal received from the base station without passing through the relay device based on the determined direct reception power; estimating a post-relay path loss, which is a path loss from the relay device to the communication terminal, based on a gain when the relay device receives the relay reference signal from the base station and transmits the relay reference signal to the communication terminal, the relay path loss, and the direct path loss, and estimating a first distance from the communication terminal to the relay device based on the post-relay path loss; A program that executes the following.

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