Distance estimation system, information processing device, distance estimation method

Abstract

To improve the accuracy of distance estimation. [Solution] The distance estimation system 1 comprises a reference communication terminal 100 and a target communication terminal 10, each performing multi-carrier transmission, and an information processing device 500 that estimates the distance between the reference communication terminal and the target communication terminal according to the communication results between the reference communication terminal and the target communication terminal. The information processing device identifies a provisional distance estimate based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, removes the long-time delayed wave component from the received wave of the received signal based on the received signal from which the long-time delayed wave component has been removed, and estimates the distance based on the intensity of the distance spectrum within a predetermined search range of the distance including the provisional estimate.

Description

[Technical Field]

[0001] The present invention relates to a distance estimation system, an information processing device, and a distance estimation method. [Background technology]

[0002] A technique for estimating the distance to a target is known, which includes a transmitting means for transmitting a transmission signal and a receiving means for receiving the reflected wave of the transmission signal as a received signal, and then processes the received signal to detect the target (see Patent Document 1).

[0003] In the above technology, the radar device includes an FFT transformation means for Fourier transforming a received signal into frequency spectrum data, a peak frequency detection means for detecting the peak frequency of the frequency spectrum data, a data extraction means for extracting data near the peak frequency from the frequency spectrum data, an inverse FFT transformation means for inversely transforming the data near the peak frequency into time-axis data, and a target detection means for detecting a target by performing high-resolution processing on the time-axis data. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-132250 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, round-trip based channel sounding is known as a distance estimation method between two communication terminals. In round-trip, distance is measured by the two communication terminals coordinating to alternately send and receive signals. As for channel sounding, for example, specifically, multi-carrier phase-based distance estimation is known, which estimates distance by comparing the received phases of unmodulated carrier transmissions across multiple frequencies.

[0006] On the one hand, in channel sounding, it is necessary to remove the influence of reflected waves and delayed waves that are factors causing estimation degradation. For this purpose, in channel sounding, for example, high-resolution multipath separation techniques such as the MUSIC (MUltiple SIgnal Classification) algorithm, or round-trip signal transmission that removes the phase of the local oscillator by multiplying the signal reaching the target communication terminal (target) from the reference communication terminal (anchor node) and the signal reaching the anchor node from the target are used.

[0007] However, when each propagation path between the anchor node and the target is composed of, for example, L paths (propagation paths), when considering the duplication with the same delay time as one path by multiplying the bidirectional signals, L(L + 1) / 2 paths are generated and the number of paths increases. When the number of paths increases, there is a problem that the accuracy of distance estimation decreases when it exceeds the resolution of the multipath separation technique.

[0008] The present invention takes the above problems as an example and aims to provide a technique for improving the estimation accuracy of distance.

Means for Solving the Problems

[0009] To achieve the above object, a distance estimation system according to the present invention includes a reference communication terminal and a target communication terminal that each perform multi-carrier transmission, and an information processing unit that estimates the distance between the reference communication terminal and the target communication terminal according to the communication result between the reference communication terminal and the target communication terminal. The distance estimation system comprises an information processing device, wherein the information processing device identifies a provisional estimate of the distance based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, removes the long-time delayed wave component from the received wave of the received signal based on the provisional estimate, calculates the distance spectrum of the received signal based on the received signal from which the long-time delayed wave component has been removed, and estimates the distance based on the intensity of the distance spectrum within a predetermined search range of the distance including the provisional estimate. [Effects of the Invention]

[0010] The distance estimation system according to the present invention can improve the accuracy of distance estimation. [Brief explanation of the drawing]

[0011] [Figure 1] This is a functional block diagram schematically showing the configuration of a distance estimation system according to an embodiment of the present invention. [Figure 2] This flowchart shows an example of the distance estimation process in the distance estimation system according to this embodiment. [Figure 3] This is a schematic diagram illustrating the round-trip transmission performed between a reference communication terminal and a target communication terminal in the distance estimation system according to this embodiment. [Figure 4] This figure illustrates the process of identifying a provisional distance estimate based on a received signal in the distance estimation system according to this embodiment. [Figure 5] This figure illustrates the process of removing long-time delayed wave components from the received wave of a received signal in the distance estimation system according to this embodiment. [Figure 6] This figure shows an example of the distance spectrum of a received signal calculated based on the received signal from which the long-time delayed wave component has been removed in the distance estimation system according to this embodiment. [Figure 7] This figure shows an enlarged view of region A in Figure 6. [Figure 8]This figure shows an example of distance estimation results between the distance estimation system according to this embodiment and the distance estimation system in the reference example. [Modes for carrying out the invention]

[0012] 1. Overview of the Embodiment First, a general overview of a typical embodiment of the invention disclosed in this application will be provided. In the following description, reference numerals in the drawings corresponding to the components of the invention are indicated in parentheses as an example.

[0013] [1] A distance estimation system (1) comprising a reference communication terminal (100) and a target communication terminal (10) that each perform multi-carrier transmission, and an information processing device (500) that estimates the distance between the reference communication terminal and the target communication terminal according to the communication result between the reference communication terminal and the target communication terminal, wherein the information processing device identifies a provisional estimate of the distance based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, removes the long-time delayed wave component from the received wave of the received signal based on the received signal from which the long-time delayed wave component has been removed, and estimates the distance based on the intensity of the distance spectrum within a predetermined search range of the distance including the provisional estimate.

[0014] [2] The distance estimation system according to [1], wherein the provisional estimate is the smallest index among the indices that exceed a threshold determined based on the maximum peak in the waveform converted to the time response of the received signal.

[0015] [3] A distance estimation system according to [1] or [2], which estimates the distance based on the maximum intensity of the distance spectrum within the search range.

[0016] [4] The distance estimation system according to any one of [1] to [3], wherein the distance spectrum is calculated by converting the received signal from which the long-time delayed wave component has been removed into a frequency domain signal, and separating the multipath included in the frequency domain signal.

[0017] [5] An information processing device (500) that estimates the distance between a reference communication terminal (100) and a target communication terminal (10) according to the communication results of the reference communication terminal and the target communication terminal, respectively, the information processing device identifies a provisional estimate of the distance based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, removes a long-time delayed wave component from the received wave of the received signal based on the provisional estimate, calculates the distance spectrum of the received signal based on the received signal from which the long-time delayed wave component has been removed, and estimates the distance based on the intensity of the distance spectrum within a predetermined search range of the distance including the provisional estimate.

[0018] [6] A distance estimation method for estimating the distance between a reference communication terminal (100) and a target communication terminal (10) according to the communication results of the reference communication terminal and the target communication terminal, wherein an information processing device (500) identifies a provisional estimate of the distance based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, removes the long-time delayed wave component from the received wave of the received signal based on the provisional estimate, calculates the distance spectrum of the received signal based on the received signal from which the long-time delayed wave component has been removed, and estimates the distance based on the intensity of the distance spectrum within a predetermined search range of the distance including the provisional estimate.

[0019] 2. Specific Examples of Embodiments Hereinafter, a distance estimation system, information processing device, and distance estimation method according to embodiments of the present invention will be described with reference to the drawings.

[0020] Figure 1 is a functional block diagram schematically showing the configuration of a distance estimation system according to an embodiment of the present invention. As shown in Figure 1, the distance estimation system 1 consists of a target communication terminal 10, a reference communication terminal 100, and a server 500. In the distance estimation system 1, the target communication terminal 10 is a terminal that moves together with the target object whose position is to be estimated. In the distance estimation system 1, the reference communication terminal 100 is a terminal that communicates wirelessly with the target communication terminal 10 and acquires the information necessary for estimating the distance to the target communication terminal 10, which is required for the distance estimation method.

[0021] The reference communication terminal 100 is an electronic device capable of multi-carrier transmission. The reference communication terminal 100 may be a device used to estimate the position coordinates of the target communication terminal 10 by wireless communication such as a radio beacon, or it may be an electronic device such as a smartphone, tablet terminal, or various types of computers.

[0022] In the distance estimation system 1, in order for the reference communication terminal 100 to estimate the distance to the target communication terminal 10, it is required that the reference communication terminal 100 is in a state where it can communicate with the target communication terminal 10. However, as long as the reference communication terminal 100 and the target communication terminal 10 can communicate, there is no particular limit to the number of target communication terminals 10 and reference communication terminals 100 within the distance estimation system 1.

[0023] The target communication terminal 10 is an electronic device capable of multi-carrier transmission, similar to the reference communication terminal 100. The target communication terminal 10 can be any electronic device capable of communicating with the reference communication terminal 100 via wireless communication; for example, it could be a smartphone, tablet, or various types of computers. The target communication terminal 10 and the reference communication terminal 100 may be the same electronic device, or they may be different electronic devices capable of communicating with each other. .

[0024] Both the target communication terminal 10 and the reference communication terminal 100 have control units 11, 110, storage units 12, 120, and communication units 13, 130.

[0025] The control units 11 and 110 are implemented by a computer such as a microcomputer, which is comprised of a processor such as an MCU (Micro Control Unit) (not shown) and a memory for calculations such as RAM (Random Access Memory). The MCU is a computing device that realizes various functions as the target communication terminal 10 or reference communication terminal 100 by executing the calculation processing of a program. The memory is a volatile memory in which the program processed by the MCU is stored. The control units 11 and 110 store the functional programs stored in the storage units 12 and 120 into the memory. The functional programs stored in the storage units are programs for realizing various functions of the target communication terminal 10 or reference communication terminal 100 in this embodiment. Programs corresponding to the functions to be realized are sequentially stored in the memory and executed sequentially by the MCU. The program is composed of functions and fixed values ​​corresponding to the function. When the program is executed, not only functions but also data, which are fixed values, are required.

[0026] The memory units 12 and 120 store identification information that can uniquely identify each target communication terminal 10 or reference communication terminal 100 within the distance estimation system 1, the position coordinates of the reference communication terminal 100 itself, and programs that can be executed by the control units 11 and 110 described above.

[0027] Communication units 13 and 130 both transmit and receive multiple carriers and perform multi-carrier transmission, where each carrier has a different wavelength. Through multi-carrier transmission, communication units 13 and 130 enable either the reference communication terminal 100 or the target communication terminal 10 to communicate with the other of the target communication terminal 10 or the reference communication terminal 100. The multi-carrier transmission used by the target communication terminal 10 and the reference communication terminal 100 includes, for example, OFDM (Orthogonal Frequency-Division Multiplexing) such as Wi-Fi and LTE, and frequency-hopping spread spectrum such as Bluetooth®.

[0028] Server 500 is an example of an information processing device. Server 500 can, for example, communicate the communication results between a reference communication terminal 100 and a target communication terminal 10 via wireless or wired communication. Server 500 is an example of a computer, such as a PC or server device, realized by a processor (such as an MCU, not shown), a memory for calculations (such as RAM, or Random Access Memory), and a memory unit for storing programs and processing data. The MCU is a calculation unit that realizes various functions of Server 500, as described below, by executing the calculations of a program. The memory is a volatile memory in which programs processed by the MCU are stored. Server 500 stores the functional programs stored in the memory. The functional programs stored in the memory are programs for realizing various functions of Server 500 in this embodiment. The memory sequentially stores programs corresponding to the functions to be realized and is executed sequentially by the MCU. The programs consist of functions and fixed values ​​corresponding to the functions. When a program is executed, not only functions but also fixed value data are required.

[0029] The server 500, with the hardware configuration and programs described above, comprises functional blocks such as a control unit 510, a storage unit 520, and a communication unit 530.

[0030] The control unit 510, in cooperation with the MCU and memory, executes a program stored in the storage unit 520, thereby enabling the distance estimation system by the server 500 to perform the following processing. The system implements the functions of an information processing device in M1 and performs a distance estimation method for the target communication terminal 10.

[0031] The memory unit 520 is implemented using non-volatile memory such as EEPROM (Electrically Erasable Programmable Read-Only Memory). The memory unit 520 stores functional programs for implementing various functions. The memory unit 520 also stores various processing data used by the server 500, such as information used when estimating the distance between the target communication terminal 10 and the reference communication terminal 100, specifically numerical values ​​used for distance estimation and information on calculation formulas described later.

[0032] The communication unit 530 can communicate with external devices, i.e., the reference communication terminal 100, for example, by wireless or wired communication via a communication interface (not shown). The communication unit 530 may also be able to communicate with the target communication terminal 10.

[0033] The server 500 may also be equipped with an operation unit and a display unit, which are input interfaces for the user to operate the server 500 and output interfaces for the user to perceive the operating status of the server 500.

[0034] Examples of hardware configurations for implementing the control unit include various touch panels, keyboards, numeric keypads, buttons, etc. However, the hardware configuration for implementing the control unit is not limited to the examples described above; it only needs to have the functionality to receive input from the user to operate the server 500. The control unit may, for example, accept operations via commands from various communication interfaces via the communication unit 530, or it may accept operations via voice command input.

[0035] The hardware configuration for the display unit is a display device equipped with a functional unit for the user to perceive the operating status of the server 500, such as an LCD (Liquid Crystal Display) or an organic EL. If the operation unit and display unit are, for example, a touch panel, then the operation unit function and the display unit function are integrated. Furthermore, the server 500 may not have some of the functions of an operation unit or display unit. Also, the server 500 is not limited to having an operation unit and display unit; for example, the operation unit and display unit functions of the server 500 may be realized from other information processing terminals such as a reference communication terminal 100, a smartphone, or a tablet terminal.

[0036] Next, we will describe the specific processing of the distance estimation method for the target communication terminal 10, which is performed by the server 500 in the distance estimation system 1.

[0037] Figure 3 is a schematic diagram showing round-trip transmission between a reference communication terminal 100 and a target communication terminal 10 in the distance estimation system according to this embodiment.

[0038] Let n be the subcarrier index at the anchor node, the reference communication terminal 100, and f be the subcarrier frequency. n , the phase of the local oscillator is θ A (n) Then the complex band signal u of the transmitted tone signal A (n) is given by the following equation (1).

[0039] TIFF2026092904000002.tif7170

[0040] Let H(n) be the channel in the propagation path, and at the target communication terminal 10, the received downwave signal is converted to a baseband signal by a downconverter carrier. Convert signal u T (n) is given by the following equation (2).

[0041] TIFF2026092904000003.tif7170

[0042] Here, assuming that the propagation path is in a one-wave environment in a line-of-sight (LOS) space, H(n) is given by the following equation (3).

[0043] TIFF2026092904000004.tif7170

[0044] Here, a0 is the channel gain and τ0 is the time delay. Assuming the distance is d and the speed of light is c, then τ0 = d / c. Therefore, the received down-converted signal u T (n) on the target side shown in Equation (2) is given by the following equation (4).

[0045] TIFF2026092904000005.tif7170

[0046] Similarly, the complex band signal v T (n) of the transmission tone signal from the target communication terminal 10 to the reference communication terminal 100 is given by the following equation (5).

[0047] TIFF2026092904000006.tif7170

[0048] On the other hand, the down-converted signal v A (n) of the signal reaching the reference communication terminal 100 is given by the following equation (6).

[0049] TIFF2026092904000007.tif17170

[0050] The received down-converted signal u T (n) on the target side fed back from the target communication terminal 10 to the reference communication terminal 100 and the down-converted signal v A (n) held by the reference communication terminal 100 are used to multiply the received down-converted signal u T (n) on the target side and the down-converted signal v A (n) on the anchor node side to obtain a signal s(n) (n = 1, 2,..., N C) can be expressed by the following equation (7).

[0051] TIFF2026092904000008.tif26170

[0052] As shown in equation (7), in server 500, the local oscillator phases on the anchor node side and the target side are canceled out by the product operation represented by equation (7), and a signal s(n) with a phase displacement amount proportional to the propagation path distance d = c·τ0 is obtained.

[0053] Figure 2 is a flowchart illustrating an example of distance estimation processing in the distance estimation system 1 according to this embodiment. Figure 2 shows the processing related to the distance estimation method performed by the server 500 in the distance estimation system 1. As shown in Figure 2, the server 500, through the cooperation of the MCU and memory of the control unit 510, executes a program stored in the storage unit 520, thereby realizing its function as an information processing device in the distance estimation system 1 and executing the distance estimation method for the target communication terminal 10.

[0054] In the reference communication terminal 100 and the target communication terminal 10, the signal s(n) shown in equation (7) can be considered as a frequency response. Therefore, the server 500 converts the signal s(n) into a time-response signal using an inverse fast Fourier transform (IFFT) (step S101). At this time, the number of points in the IFFT is N. IFFT is, N C Set it to a larger value than that.

[0055] Figure 4 is a diagram illustrating the process of identifying a provisional distance estimate based on a received signal in the distance estimation system 1 according to this embodiment. The waveform shown in Figure 4 is obtained by converting the signal s(n) into a time-response signal using IFFT in step S101.

[0056] Server 500 determines the maximum peak A of the amplitude in a predetermined search range for the signal s(n) shown in Figure 4, which has been converted. P Detect (step S102). The maximum amplitude peak A shown in Figure 4.P The search range SR is the range of the index corresponding to the range between the assumed minimum and maximum distance d between the reference communication terminal 100 and the target communication terminal 10.

[0057] Server 500 exhibits the maximum amplitude peak A shown in Figure 4. P Based on this, the maximum peak A P Peak A of the leading wave is a peak that occurred prior to the preceding peak. f Threshold A for detection B Set it as shown in equation (8) below (step S103). Peak A of the leading wave f is threshold A B Among the signal peaks exceeding a certain value, this is the peak with the smallest distance, i.e., the peak with the smallest index value. This is the leading wave peak A. f The index of I f Let's assume that in equation (8), A SL The index of the signal converted to a time response ranges from 0 to I. f This is the side lobe level, which is the average amplitude between the two points. Also, η is the threshold A. B These are parameters for setting [something].

[0058] A B =η·(A P -A SL )+A SL ...(8)

[0059] Server 500 is Peak A f Index I f Detect this index I f This is used as a provisional distance estimate (step S104).

[0060] Figure 5 is a diagram illustrating the process of removing long-time delayed wave components from the received wave of the received signal in the distance estimation system 1 according to this embodiment.

[0061] As shown in Figure 5, the server 500 uses the waveform obtained by converting s(n) into a time response to the index I detected in step S104. fShift the window function so that the gain of the window function is maximized. The server 500 weights the output of the waveform obtained by converting s(n) into the time response based on the window function. By weighting the output of the waveform converted into the time response, the server 500 performs filtering processing to remove the peak of the waveform with a large index value in the signal converted into the time response, that is, the long-delay wave (step S105).

[0062] The server 500 converts the signal obtained by converting s(n) into the time response into a frequency-domain signal by performing a fast Fourier transform (FFT) on the signal from which the long-delay wave has been removed (step S106).

[0063] The server 500 calculates a correlation matrix while shifting the subchannel corresponding to the subarray for the signal converted into the frequency-domain signal in step S106 (step S107). Specifically, in step S107, the received I / Q signals with a predetermined subchannel length NS (< NC) with respect to the channel length NC are used as vectors, and multiplied by their complex conjugate transpose vectors. This operation is performed while shifting the subchannel, and by adding them, a correlation matrix of NS rows and NS columns is calculated. Further, in order to improve the separation degree of the arrival paths, a random matrix of NS rows and NT (> NS) columns may be multiplied by the subchannel vector to calculate a compressed subchannel vector as a preprocessing, and a correlation matrix of NS rows and NS columns may be calculated in the same manner. Furthermore, the path separation characteristic of the correlation matrix may be improved by adding the forward correlation matrix calculated while shifting from the lower frequency to the higher frequency and the backward correlation matrix calculated while shifting from the higher frequency to the lower frequency.

[0064] Figure 6 shows an example of a distance spectrum calculated by removing the long-time delayed wave component from the received signal in the distance estimation system 1 according to this embodiment. Figure 7 is an enlarged view of region A in Figure 6. In Figures 6 and 7, the vertical axis represents the intensity of the frequency domain signal (arriving signal), and the horizontal axis represents the round-trip distance. Figures 6 and 7 show the distance spectrum ds1 from the distance estimation system 1 and the distance spectrum ds2 from the reference example distance estimation system. The reference example distance estimation system is a system that estimates distance without performing the processing of step S105 in the distance estimation system 1.

[0065] Server 500 corresponds to index I, which is the provisional distance estimate identified in step S104. f The search range SR2 before and after (see Figures 6 and 7) is set as the search range for distance d (step S108).

[0066] Server 500 performs eigenvector decomposition on the correlation matrix calculated in step S107 and calculates the distance spectrum (step S109).

[0067] Server 500 uses peak A, which is the peak with the maximum intensity of the distance spectrum ds1 within the search range SR2, to estimate the distance d. ds1 It is detected as such (step S110).

[0068] Server 500 detects peak A in step S110. ds1 The index is converted and estimated as distance d (step S111). In Figures 6 and 7, the shortest distance peak A of the distance spectrum ds1 by the distance estimation system 1 is shown. ds1 The distance d estimated from this is 11.0m / 2 = 5.5m. On the other hand, the shortest distance peak A in the distance spectrum ds2 obtained by the distance estimation system in the reference example is ds2 The estimated distance d is 11.7m / 2 = 5.85m.

[0069] As described above, when comparing the distance spectrum ds1 obtained by distance estimation system 1 with the distance spectrum ds2 obtained by the reference example distance estimation system, the shortest distance peak A in distance spectrum ds1 ds1 The shortest distance peak A in the distance spectrum ds2 is ds2 This shows that the error between the calculated distance and the actual distance is smaller.

[0070] Figure 8 shows an example of distance estimation results between the distance estimation system 1 according to this embodiment and the distance estimation system of the reference example.

[0071] In Figure 8, the vertical axis shows the cumulative distribution function (CDF), and the horizontal axis shows the distance. In Figure 8, the distance d Figure 8 shows the distance estimation results from distance estimation system 1 and the reference example distance estimation system at distances of 2.0m, 5.0m, 8.0m, and 11.0m, respectively. In Figure 8, the cumulative distribution function of the distance estimation results from distance estimation system 1 is shown by a solid line, and the cumulative distribution function of the distance estimation results from the reference example distance estimation system is shown by a dashed line.

[0072] As shown in Figure 8, compared to the distance estimation results from the reference example distance estimation system, the difference between the set distance d and the estimated result is smaller for distance estimation system 1. The median estimation error for distance estimation results from the reference example distance estimation system is 0.5m or more, while the median estimation error for distance estimation results from distance estimation system 1 is 0.5m or less.

[0073] As explained above, in the distance estimation system 1, the server 500 uses the received signals of the reference communication terminal 100 transmitted and received between the reference communication terminal 100 and the target communication terminal 10, which each perform multi-carrier transmission, to determine the index I as a provisional estimate of distance d. f Identify it. Server 500 is index I fBased on this, the long-time delayed wave component is removed from the received waveform of the received signal, specifically the waveform obtained by converting s(n) into a time response. Server 500 calculates the distance spectrum ds1 of the received signal based on the received signal from which the long-time delayed wave component has been removed, and index I f Within a predetermined search range SR2 that includes [the specified location], the distance d is estimated based on the intensity of the distance spectrum ds1.

[0074] Specifically, in the distance estimation method performed by server 500 in distance estimation system 1, the provisional estimate is the maximum peak A of the amplitude in the time response of signal S(n). P Threshold A based on this B The smallest index I among signals exceeding this value f That's fine.

[0075] Furthermore, in the distance estimation method executed by the server 500 in the distance estimation system 1, the maximum value of the intensity of the distance spectrum ds1 in the distance search range SR2, i.e., peak A ds1 The distance d may be estimated based on this.

[0076] Furthermore, in the distance estimation method performed by the server 500 in the distance estimation system 1, the distance spectrum ds1 may be calculated using a multipath separation technique that converts the received signal, from which the long-time delayed wave component has been removed, into a frequency domain signal and separates the multipath components contained in the frequency domain signal.

[0077] To eliminate the effects of reflected and delayed waves, which degrade estimation, channel sounding employs high-resolution multipath separation techniques such as the MUSIC algorithm and round-trip signal transmission, as described above. If the number of paths increases due to the product of the bidirectional signals in the round-trip propagation paths between the reference communication terminal 100 and the target communication terminal 10, the accuracy of distance estimation may decrease if the resolution of the multipath separation technique is exceeded.

[0078] Here, according to the distance estimation method performed by server 500 in distance estimation system 1, server 500 uses index I f Based on this, by removing the long-time delayed wave component from the waveform obtained by converting s(n) into a time response, the influence of long-distance paths can be suppressed from the increasing number of paths. As a result, the resolution of the multipath separation technique can be effectively utilized according to the distance estimation method performed by server 500, thereby improving the accuracy of distance estimation while suppressing the degradation of distance estimation accuracy.

[0079] Furthermore, those skilled in the art may modify the present invention as appropriate in accordance with prior art knowledge. Such modifications, insofar as they still possess the configuration of the present invention, are of course included within the scope of the present invention. That is the case.

[0080] For example, in distance estimation system 1, an example was described in which the information processing device that performs the distance estimation method is a server 500, but the present invention is not limited to this. The information processing device that performs the distance estimation method may be an information processing device other than the server 500. Also, the information processing device that performs the distance estimation method and the reference communication terminal 100 may be a single device, that is, the reference communication terminal 100 may be the device that performs the distance estimation method.

[0081] For example, in distance estimation system 1, the high-resolution multipath separation technique is not limited to the MUSIC method, but may be performed by other methods. [Explanation of symbols]

[0082] 1... Distance estimation system, 10... Target communication terminal, 11, 110, 510... Control unit, 12, 120, 520... Memory unit, 13, 130, 530... Communication unit, 100... Reference communication terminal, 500... Server (information processing device), A B ...Peak threshold, A d ,A ds1 ,A ds2 ...peak, A f ...Peak of the leading wave, A P...Maximum peak, d...distance, ds1...distance spectrum, ds2...distance spectrum, SR, SR2...search range, I f ...index

Claims

1. Each of the following is a reference communication terminal and a target communication terminal that perform multi-carrier transmission, An information processing device that estimates the distance between the reference communication terminal and the target communication terminal according to the communication result between the reference communication terminal and the target communication terminal, It is a distance estimation system equipped with, The aforementioned information processing device is Based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, a provisional estimate of the distance is determined. Based on the aforementioned provisional estimate, the long-time delayed wave component is removed from the received wave of the received signal. Based on the received signal from which the long-time delayed wave component has been removed, the distance spectrum of the received signal is calculated. The distance is estimated based on the intensity of the distance spectrum within a predetermined search range of the distance, including the provisional estimate. Distance estimation system.

2. The aforementioned provisional estimate is the index with the smallest value among the indices that exceed a threshold determined based on the maximum peak in the waveform converted to the time response of the received signal. The distance estimation system according to claim 1.

3. The distance is estimated based on the maximum intensity of the distance spectrum within the search range. The distance estimation system according to claim 1.

4. The distance spectrum is calculated by converting the received signal, from which the long-time delayed wave component has been removed, into a frequency domain signal, and separating the multipath components included in the frequency domain signal. A distance estimation system according to any one of claims 1 to 3.

5. This is an information processing device that estimates the distance between a reference communication terminal and a target communication terminal according to the communication results of a reference communication terminal and a target communication terminal that perform multi-carrier transmission, respectively. Based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, a provisional estimate of the distance is determined. Based on the aforementioned provisional estimate, the long-time delayed wave component is removed from the received wave of the received signal. Based on the received signal from which the long-time delayed wave component has been removed, the distance spectrum of the received signal is calculated. The distance is estimated based on the intensity of the distance spectrum within a predetermined search range of the distance, including the provisional estimate. Information processing device.

6. This distance estimation method estimates the distance between a reference communication terminal and a target communication terminal according to the communication results of the reference communication terminal and the target communication terminal, respectively, which perform multi-carrier transmission. Information processing device, Based on the received signal of the reference communication terminal transmitted and received between the reference communication terminal and the target communication terminal, a provisional estimate of the distance is determined. Based on the aforementioned provisional estimate, the long-time delayed wave component is removed from the received wave of the received signal. Based on the received signal from which the long-time delayed wave component has been removed, the distance spectrum of the received signal is calculated. The distance is estimated based on the intensity of the distance spectrum within a predetermined search range of the distance, including the provisional estimate. Distance estimation method.

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