Reception device, reception method, control circuit, and storage medium

Abstract

A reception device (100) is characterized by comprising: a reception antenna (2) that receives a wireless signal including a known sequence transmitted by a plurality of different frequency sub-bands; a frequency response estimation unit (31) that estimates the frequency response of a carrier frequency by which the known sequence is received, among each of the plurality of frequency sub-bands; a phase change amount calculation unit (32) that calculates the phase change amount of the estimated value of the frequency response between a plurality of carrier frequencies within a frequency sub-band; an interpolation processing unit (34) that interpolates the phase change amount between different frequency sub-bands, on the basis of the calculated phase change amounts; and a channel coupling unit (35) that couples the frequency responses in a phase coherent manner on the basis of the interpolated phase change amount to obtain a coupled frequency response.

Description

Receiving device, receiving method, control circuit and storage medium

[0001] The present disclosure relates to a receiving device, a receiving method, a control circuit, and a storage medium for performing wireless communication.

[0002] In recent years, with the spread of IoT (Internet of Things) devices, there has been an increasing demand for location estimation technology in indoor environments using general-purpose wireless devices. Positioning accuracy in indoor environments is generally degraded by the effects of delayed waves caused by multipath interference. As one solution to mitigate this degradation in positioning accuracy, studies have been conducted to combine frequency responses from multiple different frequency subbands to obtain a wideband frequency response and estimate location based on an impulse response with higher delay time resolution. However, the frequency responses of the acquired frequency subbands contain different phase offsets for each synchronization using a phase-locked loop. Therefore, simply combining the estimated frequency responses does not result in a phase-coherent frequency response. The wideband frequency response obtained by combining frequency responses in a phase-coherent manner can be used not only for mobile station location estimation but also for obtaining a high-resolution delay profile between a transmitting station antenna and a receiving station antenna.

[0003] In order to obtain a phase-coherent frequency response, for example, Patent Document 1 discloses a method for a wireless communication system with resource allocation in which frequency subbands overlap, in which the phases of the estimated values ​​of the frequency responses of the carrier frequencies in the overlapping portions are compared to eliminate the phase offset and combine the frequency responses.

[0004] Patent No. 6959333

[0005] However, the above-described conventional technology is based on the assumption that frequency subbands overlap, and uses an estimated value of the frequency response of the carrier frequency of the overlapping portion. Therefore, there is a problem that the technology cannot be applied to cases where the bandwidths of frequency subbands that switch using a frequency hopping method are aligned without overlapping, such as in BLE (Bluetooth (registered trademark) Low Energy).

[0006] The present disclosure has been made in consideration of the above, and aims to provide a receiving device that can obtain a frequency response wider than that of a single frequency subband by combining frequency responses in a phase-coherent manner when the bandwidths of the frequency subbands are aligned without overlapping.

[0007] In order to solve the above-mentioned problems and achieve the object, the receiving device according to the present disclosure is characterized by comprising: a receiving antenna that receives a radio signal including a known sequence transmitted in a plurality of different frequency subbands; a frequency response estimation unit that estimates a frequency response of a carrier frequency that receives the known sequence in each of the plurality of frequency subbands; a phase change amount calculation unit that calculates a phase change amount of an estimated value of the frequency response between a plurality of carrier frequencies within the frequency subband; an interpolation processing unit that interpolates the phase change amount between different frequency subbands based on the calculated phase change amount; and a channel combining unit that phase-coherently combines the frequency responses based on the interpolated phase change amount to obtain a combined frequency response.

[0008] The receiving device according to the present disclosure has the advantage that, when the bandwidths of the frequency subbands are aligned without overlapping, it is possible to obtain a frequency response wider than that of a single frequency subband by combining the frequency responses in a phase-coherent manner.

[0009] FIG. 1 is a diagram showing an example of the arrangement of frequency subbands used in a communication system according to a first embodiment. FIG. 2 is a diagram showing an example of the functional configuration of a receiving device according to a first embodiment. FIG. 3 is a flowchart for explaining the operation of a receiving device according to a first embodiment. FIG. 4 is a diagram showing an example of the functional configuration of a receiving device according to a second embodiment. FIG. 5 is a diagram showing an example of the functional configuration of a receiving device according to a fifth embodiment. FIG. 6 is a diagram showing dedicated hardware for realizing the functions of the receiving devices according to the first to fifth embodiments. FIG. 7 is a diagram showing the configuration of a control circuit for realizing the functions of the receiving devices according to the first to fifth embodiments.

[0010] Hereinafter, a receiving device, a receiving method, a control circuit, and a storage medium according to embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0011] First Embodiment Fig. 1 is a diagram showing an example of the arrangement of frequency subbands used in a communication system according to a first embodiment. Each frequency subband is composed of two or more carrier frequencies. Here, the j-th carrier frequency of frequency subband #i is denoted by f i,j , f i,j The frequency response of H(f i,j ) where the carrier frequency of frequency subband #i is N i where j={1, 2, ..., N i 1 shows an example of an arrangement in which the frequency subbands are arranged without overlapping or gaps, but the arrangement is not limited to this, and the frequency subbands may be arranged with gaps between them.

[0012] 2 is a diagram illustrating an example of a functional configuration of a receiving apparatus 100 according to the first embodiment. The receiving apparatus 100 includes a radio parameter setting unit 1, a receiving antenna 2, and a frequency response combining unit 3. The frequency response combining unit 3 includes a frequency response estimating unit 31, a phase change amount calculating unit 32, a frequency order sorting unit 33, an interpolation processing unit 34, and a channel combining unit 35.

[0013] The radio parameter setting unit 1 holds parameters necessary for estimating the frequency response of the transmission path of each frequency subband. For example, the parameters held by the radio parameter setting unit 1 include resource allocation information on the time axis of each frequency subband, such as a frequency hopping pattern, radio resource allocation for estimating the frequency response of the transmission path in each frequency subband, the number of resources, and known sequences for estimating the frequency response of the transmission path.

[0014] The receiving antenna 2 receives a radio signal from a transmitting device (not shown) and outputs a received signal, which is the received radio signal, to the frequency response estimating section 31 of the frequency response combining section 3 .

[0015] The frequency response estimator 31 calculates an estimate of the frequency response of the transmission path by inversely modulating the received signal output from the receiving antenna 2 with a known sequence in accordance with the parameters held in the wireless parameter setting unit 1. The frequency response estimator 31 outputs the calculated estimate of the frequency response to the phase change calculator 32. For example, a known signal in the frequency domain of the j-th carrier frequency in the frequency subband i at a certain time t is expressed as S(f i,j , t), and the received signal is R(f i,j , t), the estimated value of the frequency response is expressed by the following mathematical formula (1). Note that in the following text, a symbol may be followed by a hat symbol "^" instead of a symbol with a hat symbol "^" above it. For example, the estimated value of the frequency response "H^(f i,j , t) has the same meaning as the left side of equation (1).

[0016]

[0017] The frequency response estimation unit 31 estimates the number of resources N for estimating the transmission path of each carrier frequency. p(i,j) For example, the frequency response estimator 31 may average the estimated value of the frequency response of each carrier frequency including the same phase offset in units of carrier frequency according to the averaged frequency response estimate H^ ave (f i,j ) can be calculated using the following equation (2):

[0018]

[0019] Furthermore, the frequency response estimator 31 may compensate the estimated value of the frequency response of each carrier frequency for the frequency response of an RF (Radio Frequency) circuit (not shown) of the receiver 100. In this case, it is conceivable to multiply the estimated value of the frequency response of the RF circuit by the complex conjugate of the frequency response measured in advance for each carrier frequency.

[0020] The phase change amount calculation unit 32 calculates the phase change amount of the frequency response estimate between adjacent carrier frequencies that have the same phase offset with respect to the frequency response estimate output by the frequency response estimation unit 31, and outputs the calculated phase change amount and the frequency response estimate received from the frequency response estimation unit 31 to the frequency order sorting unit 33. Note that the phase change amount calculation unit 32 may calculate the phase change amount by multiplying one complex value by the complex conjugate of the other frequency response estimate, and output the complex number as is, or may calculate and output the phase angle. For example, ave (f i,j ) and H^ ave (f i,j+1 ), the amount of phase change is expressed by the following equation (3).

[0021]

[0022] Here, "Arg{·}" means the phase angle of a complex number. "H*" means the complex conjugate of "H". Similarly, hereinafter, symbols with "*" will mean the complex conjugate of the symbol. Also, the phase change amount θ(f i,j+0.5 ) is not affected by the phase offset, so it may be averaged over the phase change amounts of the same frequency calculated in the same way for different frequency hopping.

[0023] The frequency order sorting unit 33 sorts the phase change amount and frequency response estimate values ​​output by the phase change amount calculation unit 32 in order of frequency, in accordance with the time domain resource allocation information for each frequency subband held in the radio parameter setting unit 1, and outputs them to the interpolation processing unit 34. Note that if a frequency response cannot be obtained for a frequency subband, the frequency order sorting unit 33 sorts the frequency response estimate value and phase change amount corresponding to that subband as null values, meaning no value, and outputs them.

[0024] The interpolation processing unit 34 interpolates the phase change amounts between frequency subbands for the phase change amounts of all frequency subbands or some adjacent frequency subbands output by the frequency order sorting unit 33, and outputs the interpolated phase change amounts to the channel combining unit 35. Furthermore, if there is a frequency with a null value, the interpolation processing unit 34 also interpolates the phase change amount of that frequency. There are no restrictions on the interpolation method, and the interpolation processing unit 34 can use linear interpolation, spline interpolation, Lagrange polynomial interpolation, etc., for example.

[0025] When there is a gap between adjacent frequency subbands, the interpolation processing unit 34 can determine an interpolation point on the frequency axis based on the number of carriers in the frequency subband, the carrier frequency interval, etc. For example, when the carrier frequencies in the frequency subbands are equally spaced, the interpolation processing unit 34 can set the interpolation point on the frequency axis between the frequency subbands at the carrier frequency interval. When there is a gap between adjacent frequency subbands, the amplitude value of the frequency response at the interpolation point cannot be obtained, so the interpolation processing unit 34 performs interpolation using estimated values ​​of the frequency responses of all or some of the adjacent frequency subbands. In this case, the interpolation processing unit 34 may interpolate based only on the amplitude value of the frequency response, or may calculate the amplitude value after interpolating using complex values ​​of the frequency response.

[0026] The channel combining unit 35 calculates the cumulative sum of the phase change amounts from an arbitrary carrier frequency to each carrier frequency for the phase change amounts after interpolation output from the interpolation processing unit 34, thereby combining the phases of the frequency responses in a phase-coherent manner. For example, for the m-th frequency f m and the m+1th frequency f m+1 The phase change amount θ^(f m+0.5 ), the starting frequency is f m0 Then, the frequency f m0±n The phase φ(f m0±n ) can be calculated using the following equation (4):

[0027]

[0028] Here, the order is the same for all frequencies, and n is a positive integer. The channel combining unit 35 then multiplies the combined phase by the amplitude of the frequency response for each frequency, thereby obtaining a phase-coherent frequency response. For example, for the mth frequency f m The amplitude of A(f m ), the channel combiner 35 calculates the combined frequency response H comb (f m ) can be calculated using the following equation (5):

[0029]

[0030] 3 is a flowchart for explaining the operation of the receiving apparatus 100 according to the first embodiment. The frequency response estimating unit 31 of the receiving apparatus 100 performs a transmission channel estimation process for calculating an estimated value of the frequency response of the transmission channel of each carrier frequency based on a known sequence for a received signal of one frequency subband (step S101).

[0031] The phase change amount calculation unit 32 calculates the amount of phase change between adjacent carrier frequencies in the target frequency subband (step S102).

[0032] The frequency order sorting unit 33 sorts the estimated values ​​of the phase change amount and the frequency response, which are the processing results, for the target frequency subband in frequency order (step S103). Specifically, the frequency order sorting unit 33 sorts the processing results in frequency order, for example, by arranging the processing results in an array or memory corresponding to the target frequency subband, or by associating the processing results with a symbol indicating the frequency order.

[0033] The frequency order sorting unit 33 determines whether collection of the processing results of the frequency subbands to be combined has been completed (step S104). If collection of the processing results has not been completed (step S104: No), the processing is repeated from step S101. The processing from step S101 to step S103 is repeated until collection of the estimated values ​​of the phase change amount and frequency response, which are the processing results of the frequency subbands to be combined, has been completed.

[0034] When the collection of the processing results of the frequency subbands to be combined is completed (step S104: Yes), the interpolation processing unit 34 then performs interpolation processing between the frequency subbands based on the processing results of the collected frequency subbands (step S105).

[0035] The channel combining unit 35 performs a channel combining process for combining the frequency responses in a phase-coherent manner based on the interpolation process result and the estimated value of the frequency response (step S106).

[0036] As described above, the receiving apparatus 100 according to the first embodiment includes a receiving antenna 2 that receives a radio signal containing a known sequence transmitted in a plurality of different frequency subbands; a frequency response estimator 31 that estimates a frequency response of a carrier frequency that receives the known sequence in each of the plurality of frequency subbands; a phase change calculator 32 that calculates a phase change amount of an estimated value of the frequency response between the plurality of carrier frequencies within the frequency subband; an interpolator 34 that interpolates the phase change amount between the different frequency subbands based on the calculated phase change amount; and a channel combiner 35 that phase-coherently combines the frequency responses based on the interpolated phase change amount to obtain a combined frequency response. With the above configuration, the phase change amount between the frequency subbands is interpolated based on the phase change amount within the frequency subband, and the frequency responses are combined based on the interpolated phase change amount to obtain a combined frequency response. Therefore, a phase-coherent frequency response can be obtained over a bandwidth wider than a single frequency subband. Obtaining such a frequency response makes it possible to obtain a frequency response with a bandwidth greater than the operating bandwidth using a baseband modem or measuring instrument with a limited operating bandwidth. As a result, for example, it becomes possible to acquire an impulse response or a delay profile with high delay time resolution at low cost. Note that the configuration of the present disclosure is suitable when the transmission path fluctuation is small or does not change with respect to the time required for transmission path estimation of all frequency subbands.

[0037] Specifically, the channel combining unit 35 combines the phases of multiple frequency responses in a phase-coherent manner based on the amount of phase change after interpolation, and multiplies the phase and amplitude of the combined frequency response for each frequency, thereby obtaining a combined frequency response that is wider than a single frequency subband.

[0038] Note that the first embodiment can also provide a receiving method executed by receiving apparatus 100. This receiving method includes the steps of receiving a radio signal including a known sequence transmitted in a plurality of different frequency subbands, estimating a frequency response of a carrier frequency in each of the plurality of frequency subbands at which the known sequence is received, calculating a phase change amount of the estimated value of the frequency response among the plurality of carrier frequencies within the frequency subband, interpolating the phase change amount among the different frequency subbands based on the calculated phase change amount, and phase-coherently combining the plurality of frequency responses based on the interpolated phase change amount to obtain a combined frequency response.

[0039] Furthermore, according to the first embodiment, it is also possible to provide a control circuit that controls receiving apparatus 100. This control circuit controls receiving apparatus 100 that receives a radio signal including a known sequence transmitted in a plurality of different frequency subbands, and causes receiving apparatus 100 to execute the steps of: estimating a frequency response of a carrier frequency that receives the known sequence in each of the plurality of frequency subbands; calculating a phase change amount of the estimated value of the frequency response among the plurality of carrier frequencies within the frequency subband; interpolating the phase change amount among the different frequency subbands based on the calculated phase change amount; and phase-coherently combining the plurality of frequency responses based on the interpolated phase change amount to obtain a combined frequency response.

[0040] Furthermore, according to the first embodiment, it is also possible to provide a storage medium storing a program for controlling receiving apparatus 100. This storage medium stores a program for controlling receiving apparatus 100 that receives a radio signal including a known sequence transmitted in a plurality of different frequency subbands, and the program causes receiving apparatus 100 to execute the following steps: estimating a frequency response of a carrier frequency that receives the known sequence in each of the plurality of frequency subbands, calculating a phase change amount of the estimated value of the frequency response among the plurality of carrier frequencies within the frequency subband, interpolating the phase change amount among the different frequency subbands based on the calculated phase change amount, and phase-coherently combining the plurality of frequency responses based on the interpolated phase change amount to obtain a combined frequency response.

[0041] Second Embodiment Fig. 4 is a diagram showing an example of the functional configuration of a receiving device 100A according to a second embodiment. The receiving device 100A has a wireless parameter setting unit 1, a receiving antenna 2, a frequency response combining unit 3, and a position estimation processing unit 4. That is, the receiving device 100A has the position estimation processing unit 4 in addition to the configuration of the receiving device 100 according to the first embodiment. Note that, in the following, detailed description of the same parts as in the first embodiment will be omitted, and the following will mainly describe the parts that are different from the first embodiment. The position estimation processing unit 4 has an impulse response calculation unit 41 and a distance estimation processing unit 42.

[0042] The impulse response calculation unit 41 obtains an impulse response by performing an inverse discrete Fourier transform (IDFT) on the combined frequency responses output by the frequency response combination unit 3. The impulse response calculation unit 41 outputs the calculated impulse response to the distance estimation processing unit 42. Note that the impulse response calculation unit 41 may calculate the impulse response using an average value of multiple frequency responses.

[0043] The distance estimation processing unit 42 estimates the distance to a transmitting device (not shown) that is the source of the wireless signal based on the impulse response output by the impulse response calculation unit 41. Specifically, the distance estimation processing unit 42 detects the rising edge of the impulse response, and calculates the distance d to the transmitting device using the following equation (6), where c is the high speed, assuming that the delay time until the rising edge is the propagation delay time τ of the direct wave.

[0044]

[0045] Alternatively, multiple receiving devices 100A may be used to collect distances obtained by each receiving device 100A, and the position of the transmitting device may be estimated based on the distances from the multiple receiving devices 100A to the transmitting device and the position information of each receiving device 100A. In this case, the process of estimating the position of the transmitting device may be executed by one of the multiple receiving devices 100A, or may be executed by a server different from the receiving device 100A.

[0046] As described above, the receiving device 100A according to the second embodiment can achieve the same effects as the receiving device 100 according to the first embodiment. Furthermore, the receiving device 100A further includes an impulse response calculation unit 41 that obtains an impulse response by performing an inverse Fourier transform based on the combined frequency response, and a distance estimation processing unit 42 that estimates the distance to the transmitting device, which is the source of the wireless signal, based on the impulse response. Here, as described above, the receiving device 100A estimates the distance to the transmitting device based on the impulse response obtained based on the combined frequency response, which has a bandwidth wider than that of a single frequency subband. Since the delay time resolution of the impulse response is determined by the reciprocal of the bandwidth of the frequency response, the receiving device 100A using the combined frequency response has an improved delay time resolution of the impulse response compared to distance estimation using a single frequency subband, and can acquire the rise time of the impulse response with higher accuracy, thereby improving the accuracy of distance estimation. Estimating the position of the transmitting device using such a distance can also improve the accuracy of position estimation.

[0047] 5 is a diagram showing an example of the functional configuration of a receiving device 100B according to a third embodiment. The receiving device 100B includes a wireless parameter setting unit 1, a plurality of receiving antennas 2-1 and 2-2, a frequency response combining unit 3B, a position estimation processing unit 4B, and a combining start frequency setting unit 5. Note that multiple components having similar functions are distinguished from one another by adding a different number following a hyphen after the common reference symbol.

[0048] Each of the receiving antennas 2-1 and 2-2 has the same function as the receiving antenna 2 of the receiving device 100. The frequency response combiner 3B obtains a plurality of combined frequency responses corresponding to each of the receiving antennas 2-1 and 2-2. Specifically, the frequency response combiner 3B has a first system 30-1 and a second system 30-2, which are a plurality of systems corresponding to each of the receiving antennas 2-1 and 2-2. The first system 30-1 is a signal processing system corresponding to the receiving antenna 2-1 and includes a frequency response estimator 31-1, a phase change amount calculator 32-1, a frequency order sorter 33-1, an interpolation processor 34-1, and a channel combiner 35-1. The second system 30-2 is a signal processing system corresponding to the receiving antenna 2-2 and includes a frequency response estimator 31-2, a phase change amount calculator 32-2, a frequency order sorter 33-2, an interpolation processor 34-2, and a channel combiner 35-2.

[0049] Each of the first system 30-1 and the second system 30-2, which are multiple signal processing systems included in the frequency response combiner 3B, has the same function as the frequency response combiner 3 according to the first embodiment. The first system 30-1 and the second system 30-2 process the received signals output from the corresponding receiving antennas 2-1 and 2-2 to obtain a combined frequency response. At this time, each of the first system 30-1 and the second system 30-2 phase-coherently combines the estimated values ​​of the frequency responses, starting from a common combination start frequency set by the combination start frequency setting unit 5. Each of the first system 30-1 and the second system 30-2 outputs the acquired combined frequency response to the position estimation processing unit 4B.

[0050] The position estimation processing unit 4B includes impulse response calculation units 41-1 and 41-2 and an arrival direction estimation unit 43. Each of the impulse response calculation units 41-1 and 41-2 has the same function as the impulse response calculation unit 41 according to the second embodiment. The impulse response calculation units 41-1 and 41-2 are provided corresponding to the receiving antennas 2-1 and 2-2, respectively. The impulse response calculation unit 41-1 obtains an impulse response based on the combined frequency response generated by the first system 30-1 of the frequency response combination unit 3B based on the received signal from the receiving antenna 2-1. The impulse response calculation unit 41-2 obtains an impulse response based on the combined frequency response generated by the second system 30-2 of the frequency response combination unit 3B based on the received signal from the receiving antenna 2-2. Each of the impulse response calculation units 41-1 and 41-2 outputs the obtained impulse response to the arrival direction estimation unit 43.

[0051] The direction of arrival estimation unit 43 estimates the direction of arrival of the radio signal received by the receiving antennas 2-1 and 2-2 based on the phase difference of the preceding wave of each impulse response for the multiple impulse responses corresponding to the receiving antennas 2-1 and 2-2 output by the impulse response calculation units 41-1 and 41-2, respectively. The direction of arrival of the radio signal can also be said to be the direction of the transmitting device that transmitted the radio signal, as seen from the receiving device 100B. The direction of arrival estimation unit 43 can select the impulse response with the largest amplitude or power value as the preceding wave. The phase difference ψ between the receiving antennas 2-1 and 2-2 with respect to the preceding wave 2-1 can be calculated using the following equation (7), where h1 is the first wave component of the impulse response corresponding to the receiving antenna 2-1 and h2 is the first wave component of the impulse response corresponding to the receiving antenna 2-2.

[0052]

[0053] The arrival direction estimator 43 also estimates the phase difference ψ between the receiving antennas 2-1 and 2-2 with respect to the preceding wave. 2-1 and the distance d between the receiving antennas 2-1 and 2-2 2-1 and the wavelength λ of the center frequency of the entire bandwidth after coupling cand the following equation (8), an estimated value φ of the direction of arrival of the wireless signal received by the receiving antennas 2-1 and 2-2 is calculated. 2-1 can be estimated.

[0054]

[0055] In order to reduce the influence of the frequency response of the receiving device 100B on the DOA estimation value, the DOA estimation unit 43 may compensate the DOA estimation value with a DOA compensation value obtained by pre-measurement. Alternatively, the channel combining unit 35-1 may compensate the frequency response by dividing the frequency response of the receiving device 100B obtained by pre-measurement by the frequency response after channel combining for each carrier frequency.

[0056] Although FIG. 5 illustrates the receiving device 100B having two receiving antennas 2-1 and 2-2, the number of receiving antennas 2 may be three or more.

[0057] Alternatively, a plurality of receiving devices 100B may be used to collect directions of arrival obtained by each receiving device 100B, and the position of the transmitting device may be estimated based on the directions of arrival seen from each of the plurality of receiving devices 100B and the position information of each receiving device 100B. In this case, the process of estimating the position of the transmitting device may be executed by one of the plurality of receiving devices 100B, or may be executed by a server different from the receiving devices 100B.

[0058] The combining start frequency setting unit 5 sets a combining start frequency that the frequency response combining unit 3B uses as a starting point when combining frequency responses. The combining start frequency setting unit 5 sets the combining start frequency so that the frequency response combining unit 3B uses a common combining start frequency when generating multiple combined frequency responses corresponding to each of the multiple receiving antennas 2-1 and 2-2. In the example of FIG. 5 , the combining start frequency setting unit 5 sets a common combining start frequency for each of the channel combining units 35-1 and 35-2. A phase offset that depends on the combining start frequency remains in the phase of the combined frequency response. Therefore, by using a common combining start frequency for each of the receiving antennas 2-1 and 2-2, the phase offset remaining in the phase of the combined frequency response corresponding to each of the receiving antennas 2-1 and 2-2 becomes the same. As a result, the phase offset of the entire impulse responses between the receiving antennas 2-1 and 2-2 becomes the same in the arrival direction estimation unit 43, making it possible to accurately obtain the phase difference between the receiving antennas 2-1 and 2-2 corresponding to the arrival direction.

[0059] As described above, the receiving apparatus 100B according to the third embodiment can achieve the same effects as the receiving apparatus 100 according to the first embodiment. Furthermore, the receiving apparatus 100B further includes a frequency response combining unit 3B that includes a plurality of receiving antennas 2-1 and 2-2, a frequency response estimating unit 31, a phase change amount calculating unit 32, an interpolation processing unit 34, and a channel combining unit 35, and that obtains a plurality of combined frequency responses corresponding to the plurality of receiving antennas 2-1 and 2-2, respectively, starting from a common combining start frequency.

[0060] More specifically, the frequency response combining unit 3B has a first system 30-1 and a second system 30-2, which are multiple signal processing systems corresponding to the multiple receiving antennas 2-1 and 2-2, respectively. Each of the first system 30-1 and the second system 30-2 includes a frequency response estimating unit 31-1, 31-2, a phase change amount calculating unit 32-1, 32-2, an interpolation processing unit 34-1, 34-2, and a channel combining unit 35-1, 35-2, and obtains a combined frequency response starting from a common combining start frequency.

[0061] The receiving device 100B further includes impulse response calculation units 41-1 and 41-2 that perform an inverse Fourier transform based on each of the multiple combined frequency responses to obtain an impulse response, and a direction-of-arrival estimation unit 43 that estimates the direction of arrival of the radio signal based on the multiple impulse responses. Here, as described above, the receiving device 100B estimates the direction of arrival of the radio signal based on the impulse response obtained based on the combined frequency responses, which are broader than a single frequency subband. Since the delay time resolution of the impulse response is determined by the reciprocal of the bandwidth of the frequency response, the receiving device 100B that uses the combined frequency responses has improved delay time resolution of the impulse response compared to direction-of-arrival estimation using a single frequency subband. This allows the direction of arrival of the advance wave to be estimated while separating the advance wave and the delayed wave more accurately, thereby improving the accuracy of the direction-of-arrival estimation. When the position of the transmitting device is estimated using such a direction of arrival, the accuracy of the position estimation can also be improved.

[0062] 6 is a diagram illustrating an example of a functional configuration of a receiving device 100C according to a fourth embodiment. The receiving device 100C includes a wireless parameter setting unit 1, receiving antennas 2-1 and 2-2, a frequency response coupling unit 3C, a position estimation processing unit 4C, a coupling start frequency setting unit 5C, and an antenna switching unit 6.

[0063] The receiving device 100C has two receiving antennas 2-1 and 2-2, similar to the receiving device 100B shown in Fig. 5. In the receiving device 100B, the frequency response combining unit 3B has two signal processing systems, but the receiving device 100C has an antenna switching unit 6 in order to process the signals received by the two receiving antennas 2-1 and 2-2 with a single signal processing system.

[0064] The antenna switching unit 6 switches, in a time-division manner, which of the multiple reception signals received by the multiple reception antennas 2-1 and 2-2 is to be output to the frequency response combining unit 3C. While Fig. 6 illustrates an example in which there are two reception antennas 2, the same applies when there are three or more reception antennas 2. The antenna switching unit 6 outputs one of the reception signals output by the two reception antennas 2-1 and 2-2 to the frequency response combining unit 3C depending on the time.

[0065] The basic operation of the frequency response combining unit 3C is the same as that of the frequency response combining unit 3, but because the received signals from the two receiving antennas 2-1 and 2-2 are input in a time-division manner, the same signal processing system performs the combining process of the frequency responses of the two receiving antennas 2-1 and 2-2. The frequency response combining unit 3C outputs the combined frequency responses corresponding to each of the multiple receiving antennas 2-1 and 2-2 to the position estimation processing unit 4C in a time-division manner.

[0066] Similar to the coupling start frequency setting unit 5, the coupling start frequency setting unit 5C sets a coupling start frequency so that a common coupling start frequency is used when the frequency response combining unit 3C generates multiple combined frequency responses corresponding to each of the multiple receiving antennas 2-1 and 2-2. The frequency response combining unit 3C has one signal processing system, and therefore the coupling start frequency setting unit 5C differs from the coupling start frequency setting unit 5 in that it outputs a coupling start frequency to one channel combining unit 35. The channel combining unit 35 combines the frequency response corresponding to the receiving antenna 2-1 and the frequency response corresponding to the receiving antenna 2-2 in a time-division manner, but uses a common coupling start frequency even if the receiving antenna 2 to be processed changes.

[0067] The position estimation processing unit 4C has an impulse response calculation unit 41 and an arrival direction estimation unit 43. The impulse response calculation unit 41 has the same function as the impulse response calculation units 41-1 and 41-2 shown in FIG. 5. The combined frequency response corresponding to the receiving antenna 2-1 and the combined frequency response corresponding to the receiving antenna 2-2 are input to the position estimation processing unit 4C in a time-division manner. Therefore, the impulse response calculation unit 41 calculates the impulse response corresponding to the receiving antenna 2-1 and the impulse response corresponding to the receiving antenna 2-2 in a time-division manner, and outputs the calculated impulse responses to the arrival direction estimation unit 43. The arrival direction estimation unit 43 has the same function as the arrival direction estimation unit 43 of the position estimation processing unit 4B in FIG. 5.

[0068] As described above, the receiving apparatus 100C according to the fourth embodiment can achieve the same effects as those of the first embodiment. The receiving apparatus 100C further includes a plurality of receiving antennas 2-1 and 2-2, and a frequency response combining unit 3C including a frequency response estimating unit 31, a phase change amount calculating unit 32, an interpolation processing unit 34, and a channel combining unit 35, which obtains a plurality of combined frequency responses corresponding to the plurality of receiving antennas 2-1 and 2-2, starting from a common combining start frequency. More specifically, the frequency response combining unit 3C has a single signal processing system including the frequency response estimating unit 31, the phase change amount calculating unit 32, the interpolation processing unit 34, and the channel combining unit 35, and further includes an antenna switching unit 6 which switches, in a time-division manner, a received signal to be output to the frequency response combining unit 3C from a plurality of received signals received by the plurality of receiving antennas 2-1 and 2-2. The receiving device 100C further includes an impulse response calculation unit 41 that obtains an impulse response by performing an inverse Fourier transform based on each of the multiple combined frequency responses, and an arrival direction estimation unit 43 that estimates the arrival direction of the wireless signal based on the multiple impulse responses. Even with this configuration, the same effects as those of the third embodiment can be achieved. Furthermore, compared to the configuration of the third embodiment, it is possible to reduce the circuit scale.

[0069] In the fourth embodiment, the receiving device 100C is described as having two receiving antennas 2, but the same applies to a case where three or more receiving antennas 2 are included. For example, the antenna switching unit 6 may output the received signal of one of the three receiving antennas 2-1 to 2-3 (not shown) to the frequency response combining unit 3C in a time-division manner. In a case where three or more receiving antennas are included, the frequency response combining unit 3C may include multiple signal processing systems, and the receiving device 100C may include the same number of antenna switching units as the number of signal processing systems. For example, the receiving device 100C may include four receiving antennas 2-1 to 2-4 (not shown), and the frequency response combining unit 3C may include two signal processing systems, a first system 30-1 and a second system 30-2. In this case, the receiving device 100C may include an antenna switching unit 6-1 (not shown) that outputs a signal received from one of the receiving antennas 2-1 and 2-2 to the first system 30-1, and an antenna switching unit 6-2 (not shown) that outputs a signal received from one of the receiving antennas 2-3 and 2-4 to the second system 30-2. In this case, the position estimation processing unit 4C may include impulse response calculation units 41-1 and 41-2 corresponding to the first system 30-1 and the second system 30-2, respectively.

[0070] Fifth Embodiment Fig. 7 is a diagram showing an example of the functional configuration of a receiving device 100D according to a fifth embodiment. The receiving device 100D has a wireless parameter setting unit 1, a plurality of receiving antennas 2-1 and 2-2, a frequency response combining unit 3B, a position estimation processing unit 4D, and a combining start frequency setting unit 5. In other words, the configuration of the receiving device 100D is the same as that of the receiving device 100B according to the third embodiment shown in Fig. 5 except for the position estimation processing unit 4D, and therefore, only the parts that differ from the third embodiment will be described below.

[0071] The position estimation processing unit 4D has impulse response calculation units 41-1 and 41-2, a distance estimation processing unit 42, an arrival direction estimation unit 43, and a position estimation unit 44. The impulse response calculation units 41-1 and 41-2 and the arrival direction estimation unit 43 are the same as those in the third embodiment, and therefore detailed description thereof will be omitted here. The distance estimation processing unit 42 is the same as that in the second embodiment.

[0072] The position estimation unit 44 estimates the relative position of the transmitting device with respect to the position of the receiving device 100D based on the estimated distance to the transmitting device output by the distance estimation processing unit 42 and the estimated arrival direction of the wireless signal output by the arrival direction estimation unit 43. For example, the position estimation unit 44 estimates the relative position of the transmitting device with respect to the position of the receiving device 100D based on the estimated arrival direction φ est , estimated distance d est , the relative position of the transmitting device (x tx , y tx ) can be calculated using the following equations (9) and (10).

[0073]

[0074]

[0075] If the absolute position of the receiving device 100D is known, the position estimation unit 44 may calculate the absolute position of the transmitting device using the absolute position of the receiving device 100D and the estimated relative position.

[0076] As described above, according to the fifth embodiment, the same effects as those of the first to fourth embodiments can be achieved. Furthermore, according to the fifth embodiment, the receiving device 100D further includes impulse response calculation units 41-1 and 41-2 that obtain impulse responses by performing an inverse Fourier transform based on each of a plurality of combined frequency responses, a direction-of-arrival estimation unit 43 that estimates the direction of arrival of the radio signal based on the plurality of impulse responses, a distance estimation processing unit 42 that estimates the distance to the transmitting device that is the source of the radio signal based on the plurality of impulse responses, and a position estimation unit 44 that estimates the position of the transmitting device based on the distance estimation result and the direction-of-arrival estimation result. The receiving device 100D estimates the distance to the transmitting device and the direction of arrival of the radio signal based on the impulse response obtained based on the combined frequency responses that are broader than a single frequency subband. Therefore, the accuracy of the distance estimation can be improved, as in the second embodiment described above. Furthermore, the accuracy of the direction-of-arrival estimation can be improved, as in the third and fourth embodiments described above. Because the position of the transmitting device is estimated based on such highly accurate distance and direction of arrival estimation results, the receiving device 100D can improve the accuracy of position estimation compared to when it is based on a single frequency subband.

[0077] Next, the hardware configuration of the receiving devices 100, 100A, 100B, 100C, and 100D according to the first to fifth embodiments will be described. Each functional unit of the receiving devices 100, 100A, 100B, 100C, and 100D is realized by a processing circuit. These processing circuits may be realized by dedicated hardware or may be control circuits using a CPU (Central Processing Unit).

[0078] When the above processing circuits are realized by dedicated hardware, they are realized by a processing circuit 90 shown in Fig. 8. Fig. 8 is a diagram showing dedicated hardware for realizing the functions of the receiving devices 100, 100A, 100B, 100C, and 100D according to the first to fifth embodiments. The processing circuit 90 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0079] When the processing circuit is realized by a control circuit using a CPU, the control circuit is, for example, a control circuit 91 having a configuration shown in FIG. 9 . FIG. 9 is a diagram showing the configuration of the control circuit 91 for realizing the functions of the receiving devices 100, 100A, 100B, 100C, and 100D according to the first to fifth embodiments. As shown in FIG. 9 , the control circuit 91 includes a CPU 92 and a memory 93. The CPU 92 is also called an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), etc. The memory 93 is, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM), an EEPROM (registered trademark) (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disk).

[0080] When the above processing circuit is realized by the control circuit 91, it is realized by the CPU 92 reading and executing a program stored in the memory 93 and corresponding to the processing of each component. The memory 93 is also used as a temporary memory for each process executed by the CPU 92. The program executed by the CPU 92 may be provided in a state stored in a storage medium, or may be provided via a communication path such as the Internet. Note that some of the above functional units may be realized by dedicated hardware, and the remaining parts may be realized using programs.

[0081] The division of functional units shown above is an example. Multiple functional units may be realized by a single processing circuit, or the functions shown as a single functional unit may be divided and realized by multiple processing circuits.

[0082] The configurations described in the above embodiments are merely examples, and may be combined with other known technologies, or may be combined with other embodiments, or may include some parts of the configuration omitted or modified without departing from the spirit of the invention. For example, in the fifth embodiment, a configuration was described in which the distance estimation processing unit 42 and the position estimation unit 44 were added to the configuration of the position estimation processing unit 4B of the receiving device 100B of the third embodiment, but the distance estimation processing unit 42 and the position estimation unit 44 may be added to the configuration of the position estimation processing unit 4C of the receiving device 100C of the fourth embodiment.

[0083] 1 Radio parameter setting unit, 2, 2-1 to 2-4 Receiving antennas, 3, 3B, 3C Frequency response combining unit, 4, 4B, 4C, 4D Position estimation processing unit, 5, 5C Combined start frequency setting unit, 6, 6-1, 6-2 Antenna switching unit, 30-1 First system, 30-2 Second system, 31, 31-1, 31-2 Frequency response estimating unit, 32, 32-1, 32-2 Phase change amount calculating unit, 33, 33-1, 33-2 Frequency order sorting unit, 34, 34-1, 34-2 Interpolation processing unit, 35, 35-1, 35-2 Channel combining unit, 41, 41-1, 41-2 Impulse response calculating unit, 42 Distance estimation processing unit, 43 Arrival direction estimating unit, 44 Position estimating unit, 90 Processing circuit, 91 Control circuit, 92 CPU, 93 Memory, 100, 100A, 100B, 100C, 100D receiving device.

Claims

1. a receiving antenna for receiving a wireless signal including a known sequence transmitted in a plurality of different frequency subbands; a frequency response estimator configured to estimate a frequency response of a carrier frequency at which the known sequence is received in each of the plurality of frequency subbands; a phase change amount calculation unit that calculates a phase change amount of the estimated value of the frequency response between a plurality of the carrier frequencies in the frequency subband; an interpolation processing unit that interpolates phase change amounts between different frequency subbands based on the calculated phase change amounts; a channel combiner for phase-coherently combining the frequency responses based on the interpolated phase change amount to obtain a combined frequency response; A receiving device comprising:

2. The receiving device described in claim 1, characterized in that the channel combining unit combines the phases of the multiple frequency responses in a phase-coherent manner based on the phase change amount after interpolation, and multiplies the phase and amplitude of the combined frequency response for each frequency to obtain the combined frequency response having a bandwidth wider than that of one of the frequency subbands.

3. an impulse response calculation unit that obtains an impulse response by performing an inverse Fourier transform on the basis of the combined frequency response; a distance estimation processing unit that estimates a distance to a transmitting device that is a source of the wireless signal based on the impulse response; 3. The receiving device according to claim 1, further comprising:

4. A plurality of the receiving antennas; a frequency response combining unit including the frequency response estimating unit, the phase change amount calculating unit, the interpolation processing unit, and the channel combining unit, the frequency response combining unit obtaining a plurality of combined frequency responses corresponding to each of the plurality of receiving antennas, starting from a common combining start frequency; 3. The receiving device according to claim 1, further comprising:

5. the frequency response combiner has a plurality of signal processing systems corresponding to the plurality of receiving antennas, The receiving device according to claim 4, characterized in that each of the plurality of signal processing systems includes the frequency response estimation unit, the phase change amount calculation unit, the interpolation processing unit, and the channel combining unit, and obtains the combined frequency response starting from a common combining start frequency.

6. the frequency response combining unit has one signal processing system including the frequency response estimating unit, the phase change amount calculating unit, the interpolation processing unit, and the channel combining unit; an antenna switching unit that switches, in a time division manner, a reception signal to be output to the frequency response combining unit among a plurality of reception signals received by the plurality of reception antennas; The receiving device according to claim 4, further comprising:

7. an impulse response calculation unit that obtains an impulse response by performing an inverse Fourier transform based on each of the plurality of combined frequency responses; an arrival direction estimating unit that estimates an arrival direction of the wireless signal based on a plurality of the impulse responses; The receiving device according to claim 4, further comprising:

8. a distance estimation processing unit that estimates a distance to a transmitting device that is a source of the wireless signal based on a plurality of the impulse responses; a position estimation unit that estimates a position of the transmitting device based on the distance estimation result and the arrival direction estimation result; The receiving device according to claim 7, further comprising:

9. A receiving method executed by a receiving device, comprising: receiving a wireless signal including a known sequence transmitted in a plurality of different frequency subbands; estimating a frequency response of a carrier frequency at which the known sequence is received within each of a plurality of the frequency subbands; calculating a phase shift of the frequency response estimate between a plurality of the carrier frequencies within the frequency subband; interpolating phase changes between different frequency subbands based on the calculated phase changes; phase-coherently combining the plurality of frequency responses based on the interpolated phase change amount to obtain a combined frequency response; A receiving method comprising:

10. A control circuit for controlling a receiving device that receives a radio signal including a known sequence transmitted in a plurality of different frequency subbands, comprising: estimating a frequency response of a carrier frequency at which the known sequence is received within each of a plurality of the frequency subbands; calculating a phase shift of the frequency response estimate between a plurality of the carrier frequencies within the frequency subband; interpolating phase changes between different frequency subbands based on the calculated phase changes; phase-coherently combining the plurality of frequency responses based on the interpolated phase change amount to obtain a combined frequency response; A control circuit that causes the receiving device to execute the above.

11. A storage medium storing a program for controlling a receiving device for receiving a radio signal including a known sequence transmitted in a plurality of different frequency subbands, the program comprising: estimating a frequency response of a carrier frequency at which the known sequence is received within each of a plurality of the frequency subbands; calculating a phase shift of the frequency response estimate between a plurality of the carrier frequencies within the frequency subband; interpolating phase changes between different frequency subbands based on the calculated phase changes; phase-coherently combining the plurality of frequency responses based on the interpolated phase change amount to obtain a combined frequency response; A storage medium that causes the receiving device to execute the above.