JP7638460B2 - Radio wave arrival angle estimation device, radio wave arrival angle estimation method, control circuit, and storage medium - Google Patents

Description

The present disclosure relates to a radio wave arrival angle estimation device, a radio wave arrival angle estimation method, a control circuit, and a storage medium that use multiple frequency channels.

In recent years, a technology has been used to estimate the angle of arrival of radio waves at the receiving side. The estimated result of the angle of arrival of radio waves is used, for example, to estimate the position of a mobile station or to obtain a delay profile between a transmitting antenna and a receiving antenna. In Bluetooth (registered trademark), technologies such as AoA (Angle of Arrival) and AoD (Angle of Departure) that estimate the position from the angle of arrival of radio waves are sometimes used. When estimating the angle of arrival of radio waves, indoors, the radio waves are easily affected by multipath, where the radio waves are reflected off walls and reach the receiving side via multiple paths, and the accuracy of the estimation of the angle of arrival of radio waves may decrease. In addition, in an environment where interference from other systems occurs, the accuracy of the estimation of the angle of arrival of radio waves decreases.

As a countermeasure against multipath, Non-Patent Document 1 discloses a technique for transmitting known signals using multiple frequency channels, determining a channel impulse response from the received known signals, and separating direct wave components and delayed wave components from the channel impulse response. In this case, by frequency combining the known signals on the receiving side, it is possible to determine a channel impulse response with a frequency bandwidth wider than the frequency bandwidth of a single frequency channel. Since the time resolution of the channel impulse response is inversely proportional to the frequency bandwidth, a wider frequency bandwidth increases the time resolution of the channel impulse response, improving the accuracy of separation between the direct wave component and the delayed wave component, making it possible to suppress the delayed wave component.

As a countermeasure against interference, Patent Document 1 describes how the direction from which the interference is coming can be estimated, and beam pattern control using multiple receiving antennas can be used to direct a null in the beam pattern toward the estimated direction of arrival, thereby reducing the effects of interference.

Patent No. 6279206

R.Ayyalasomayajula, D.Vasisht, D.Bharadia, “BLoc:CSI-based Accurate Localization for BLE Tags”, In Proceedings of the 14th International Conference on emerging Networking EXperiments and Technologies, Heraklion/Crete, Greece, 4-7 December 2018; pp.126-138.

However, in an environment affected by both multipath and interference from other systems, there is a problem in that it can be difficult to estimate the angle of arrival of radio waves with high accuracy. For example, when there is a possibility that each frequency channel may be subject to interference from a different interference source, it is possible to perform interference suppression processing by applying an interference suppression weight to each frequency channel. However, the channel impulse response of frequency channels that have been subjected to interference suppression processing with different interference suppression weights depends on the interference suppression weight. As a result, frequency coupling cannot be performed across multiple frequency channels.

The present disclosure has been made in consideration of the above, and aims to provide a radio wave arrival angle estimation device that can estimate the arrival angle of radio waves with high accuracy even in an environment affected by both multipath and interference from other systems.

In order to solve the above-mentioned problems and achieve the objective, the radio wave arrival angle estimation device disclosed herein is a radio wave arrival angle estimation device that estimates the arrival direction of radio waves from a received signal that receives a signal transmitted using multiple frequency channels, and is characterized by comprising an interference measurement unit that measures the interference state for each frequency channel and generates interference information, a frequency channel group generation unit that groups the multiple frequency channels and generates frequency channel groups based on the interference information generated for each frequency channel, an interference suppression processing unit that generates interference suppression weights on a frequency channel group basis and performs interference suppression processing, a frequency channel combining unit that combines frequency channels on a frequency channel group basis for the signal after the interference suppression processing has been performed, a direct wave component extraction unit that extracts a direct wave component from the signal after the frequency channels have been combined, and a radio wave arrival angle estimation unit that estimates the arrival angle of radio waves from the direct wave component.

The radio wave arrival angle estimation device disclosed herein has the advantage of being able to estimate the arrival angle of radio waves with high accuracy even in an environment affected by both multipath and interference from other systems.

FIG. 1 is a diagram showing a configuration of a radio wave arrival angle estimation device according to a first embodiment; FIG. 1 is a diagram showing a configuration of a transmission device according to a first embodiment; FIG. 1 is a diagram showing a configuration of a receiving device according to a first embodiment; FIG. 4 is a diagram showing a detailed configuration example of an interference measurement unit shown in FIG. 3 ; FIG. 4 is a diagram showing a detailed configuration example of a frequency channel group generation unit shown in FIG. 3 ; FIG. 1 shows a known signal transmitted using 16 frequency channels. A diagram showing the communication slots shown in FIG. 6 as a frequency spectrum. FIG. 7 is a diagram showing an example of a frequency spectrum when the known signal shown in FIG. 6 is subjected to interference. FIG. 1 shows an example of a channel impulse response. 1 is a flowchart for explaining an operation of a receiving device according to a first embodiment. FIG. 13 is a diagram showing a configuration of a receiving device according to a second embodiment; 11 is a flowchart for explaining an operation of a receiving apparatus according to a second embodiment. FIG. 13 shows a known signal transmitted in the third embodiment. FIG. 1 is a diagram showing dedicated hardware for implementing the functions of a radio wave arrival angle estimation device according to first to third embodiments. FIG. 1 is a diagram showing the configuration of a control circuit for implementing the functions of a radio wave arrival angle estimation device according to first to third embodiments.

Below, the radio wave arrival angle estimation device, radio wave arrival angle estimation method, control circuit, and storage medium relating to the embodiments of the present disclosure are described in detail with reference to the drawings.

Embodiment 1.
1 is a diagram showing a configuration of a radio wave arrival angle estimation device 1 according to a first embodiment. The radio wave arrival angle estimation device 1 includes a transmission device 10 and a reception device 20. The radio wave arrival angle estimation device 1 can also be called a radio wave arrival angle estimation system. The radio wave arrival angle estimation device 1 performs communication using a plurality of frequency channels. In the radio wave arrival angle estimation device 1, the transmission device 10 transmits signals as radio waves using a plurality of frequency channels, and the reception device 20 receives the signals transmitted by the transmission device 10 and estimates the arrival angle of the radio waves from the received signals.

2 is a diagram showing the configuration of the transmitting device 10 according to the first embodiment. The transmitting device 10 has a known signal generating unit 100, a modulating unit 101, a transmitting filter unit 102, a frequency converting unit 103, and a transmitting antenna unit 104.

The known signal generating unit 100 generates a known signal used by the receiving device 20 to estimate a channel impulse response, and outputs the generated known signal to the modulating unit 101. The modulating unit 101 modulates the known signal output by the known signal generating unit 100, and outputs the modulated known signal to the transmitting filter unit 102. The transmitting filter unit 102 filters the modulated known signal output by the modulating unit 101 with a transmission filter, and outputs the filtered signal to the frequency converting unit 103. The frequency converting unit 103 converts the frequency of the filtered signal output by the transmitting filter unit 102 to match the frequency channel to be transmitted among multiple frequency channels, and outputs the frequency converted signal to the transmitting antenna unit 104. The transmitting antenna unit 104 transmits the frequency converted signal output by the frequency converting unit 103 as radio waves.

3 is a diagram showing the configuration of the receiving device 20 according to the first embodiment. The receiving device 20 has a receiving antenna unit 200, a frequency conversion unit 201, a receiving filter unit 202, a received signal storage memory unit 203, an interference measurement unit 204, a frequency channel group generation unit 205, an interference suppression processing unit 206, a frequency channel combination unit 207, a direct wave component extraction unit 208, a radio wave arrival angle estimation unit 209, and an arrival angle synthesis unit 210.

The receiving antenna unit 200 receives the signal transmitted as radio waves by the transmitting device 10 at one or more receiving antennas, and outputs the received signal to the frequency conversion unit 201. The frequency conversion unit 201 frequency converts the received signal output by the receiving antenna unit 200 to a baseband signal, and outputs the frequency-converted received signal to the receiving filter unit 202. The receiving filter unit 202 filters the frequency-converted received signal output by the frequency conversion unit 201 to a communication wave band using a receiving filter, and outputs the filtered received signal to each of the received signal storage memory unit 203 and the interference measurement unit 204.

The received signal storage memory unit 203 temporarily stores the filtered received signal output by the receiving filter unit 202. The interference measurement unit 204 measures the interference waves observed from the filtered received signal output by the receiving filter unit 202, generates interference information indicating the state of interference, and outputs the generated interference information to each of the frequency channel group generation unit 205 and the arrival angle synthesis unit 210.

The frequency channel group generation unit 205 groups the multiple frequency channels used by the radio wave arrival angle estimation device 1 based on the interference information generated by the interference measurement unit 204, and generates a frequency channel group consisting of one or multiple frequency channels. The frequency channel group generation unit 205 outputs information indicating the generated frequency channel group to the interference suppression processing unit 206.

The interference suppression processing unit 206 reads out the received signals stored in the received signal storage memory unit 203 based on information indicating the frequency channel groups generated by the frequency channel group generation unit 205, generates interference suppression weights from the received signals belonging to each frequency channel group, performs interference suppression processing, and outputs the signal after interference suppression processing to the frequency channel coupling unit 207.

The frequency channel combining unit 207 combines frequency channels for each frequency channel group on the signal after interference suppression processing output by the interference suppression processing unit 206, and outputs the combined signal to the direct wave component extraction unit 208.

The direct wave component extraction unit 208 calculates a channel impulse response for each frequency channel group for the combined signal output by the frequency channel combining unit 207, extracts the direct wave component based on the channel impulse response, and outputs the channel impulse response corresponding to the extracted direct wave component to the radio wave arrival angle estimation unit 209.

The radio wave arrival angle estimation unit 209 estimates the arrival angle of the radio waves from the channel impulse response corresponding to the direct wave component output by the direct wave component extraction unit 208, and outputs the arrival angle of the radio waves for each frequency channel group to the arrival angle synthesis unit 210.

The arrival angle synthesis unit 210 synthesizes the estimated results of the arrival angle of radio waves for each frequency channel group output by the radio wave arrival angle estimation unit 209 based on the interference information output by the interference measurement unit 204, and outputs the arrival angle estimation result.

Here, we will explain the detailed processing of the interference measurement unit 204.

Figure 4 is a diagram showing a detailed configuration example of the interference measurement unit 204 shown in Figure 3. The interference measurement unit 204 has an SINR (Signal Interference Noise Ratio) estimation unit 211, an interference power estimation unit 212, an interference arrival angle estimation unit 213, and an interference complex signal estimation unit 214. The received signal output by the reception filter unit 202 is input to each unit of the interference measurement unit 204.

The SINR estimation unit 211 estimates the SINR from the received signal and outputs the SINR estimation value as interference information. The SINR is also called the signal-to-interference-plus-noise power ratio, and represents the ratio of the total of the interference power and the noise power to the signal power. Hereinafter, the total of the interference power and the noise power is referred to as the interference plus noise power. For example, the SINR estimation unit 211 can estimate the signal power S _i,m by using a known signal as a reference sequence and calculating the correlation power of the reference sequence for the received signal. Here, i is a frequency channel index, and is an integer equal to or greater than 0 and less than N _f when N _f is the number of frequency channels. Also, m is a receiving antenna index, and is an integer equal to or greater than 0 and less than M when M is the number of receiving antennas. Regarding the interference plus noise power IN _i,m , if the modulation method used for the known signal is, for example, FSK (Frequency Shift Keying) modulation, the SINR estimation unit 211 can estimate the interference plus noise power IN _i,m by using a non-signal region, which is a frequency bin in the FSK modulation that does not transmit a signal. When the SINR estimator 211 estimates each of the signal power S _i,m and the interference noise power IN _i,m , it can estimate SINR _{i ,} which is the SINR for the i-th frequency channel, using the following equation (1).

Note that the method by which the SINR estimation unit 211 estimates the SINR is not limited to the above-mentioned method.

The interference power estimation unit 212 estimates the interference power included in the received signal and outputs the interference power estimation value as interference information. The interference power estimation unit 212 can estimate the interference power I _i from the interference noise power IN _i,m estimated by the same method as the SINR estimation unit 211. If the value of the interference noise power IN _i,m estimated by the SINR estimation unit 211 is already available, the interference power estimation unit 212 may obtain and use the interference noise power IN _i,m from the SINR estimation unit 211. The interference power estimation unit 212 can use the following formula (2) to determine the average of the interference noise power IN _i,m of the M antennas as the interference power I _i .

The interference arrival angle estimator 213 estimates an interference arrival angle, which is an arrival angle of an interference wave included in a received signal, and outputs an interference arrival angle estimate value as interference information. The interference arrival angle estimator 213 measures an interference complex signal for each receiving antenna by using a signal-free region for each receiving antenna, and can estimate an interference arrival angle using the measured interference complex signal. When there are two or more receiving antennas, the interference arrival angle θ i,m _{,l is expressed using the following formula (3) using the interval d m,l} between receiving antenna m and receiving antenna l, the phase difference φ _{i, m,l} in the interference between receiving antenna m and receiving antenna l, and the wavelength λ _i corresponding to the i-th frequency channel. The phase difference φ _i,m,l can be obtained from the interference complex signal C _i,m (n) of receiving antenna m and the interference complex signal C _i,l (n) of receiving antenna l using the following formula (4). Note that X ^* represents the complex conjugate of X. Here, n is a symbol index in a no-signal region, and is an integer equal to or greater than 0 and less than _Ns , where _Ns is the number of symbols in a no-signal region. Note that the method by which the interference arrival angle estimator 213 estimates the interference arrival angle θ _i,m,l is not limited to the above method.

The interference complex signal estimation unit 214 estimates the interference complex signal for each receiving antenna and outputs the interference complex signal estimate value as interference information. The interference complex signal estimation unit 214 can measure the interference complex signal in a manner similar to that of the interference arrival angle estimation unit 213. If the interference arrival angle estimation unit 213 has already measured the interference complex signal, the interference complex signal estimation unit 214 can acquire the interference complex signal from the interference arrival angle estimation unit 213 and output it as interference information.

The interference measurement unit 204 generates interference information including at least one of an SINR estimate, an interference power estimate, an interference arrival angle estimate, and an interference complex signal estimate, and outputs the interference information to each of the frequency channel group generation unit 205 and the arrival angle synthesis unit 210.

Next, we will explain the detailed configuration of the frequency channel group generation unit 205.

Figure 5 is a diagram showing a detailed configuration example of the frequency channel group generation unit 205 shown in Figure 3. The frequency channel group generation unit 205 has an interference clustering unit 215 and a frequency channel group determination unit 216. The frequency channel group generation unit 205 receives an SINR estimate value, an interference power estimate value, an interference arrival angle estimate value, and an interference complex signal estimate value as interference information output by the interference measurement unit 204. These interference information are input to the interference clustering unit 215. The SINR estimate value of the interference information is also input to the frequency channel group determination unit 216. The frequency channel group generation unit 205 generates a frequency channel group using one or more of the SINR estimate value, the interference power estimate value, the interference arrival angle estimate value, and the interference complex signal estimate value.

Here, we will explain the known signal transmitted by the transmitting device 10.

Figure 6 is a diagram showing a known signal transmitted using 16 frequency channels. The known signal is transmitted as a communication slot 300 using 16 frequency channels with frequency channel indexes #0 to #15. The horizontal axis of Figure 6 is frequency, and the vertical axis is time. In the case of a frequency hopping method, the order of the frequency channel indexes to be used is defined as a frequency hopping sequence, and the frequency channel to be used is changed for each packet during transmission. In the example shown in Figure 6, the frequency hopping sequence is #0, #4, #8, #12, #1, #5, #9, #13, #2, #6, #10, #14, #3, #7, #11, #15. Note that although an example of 16 frequency channels is shown here, for example, in the case of Bluetooth, the frequency channels are 40 channels from #0 to #39, and each channel has a frequency bandwidth of 2 MHz.

Figure 7 shows the communication slot 300 shown in Figure 6 as a frequency spectrum. Signal 301 is a spectrum obtained by frequency converting only the communication slot 300 portion of Figure 6, and a spectrum exists for the communication slot 300 for each frequency channel. The horizontal axis of Figure 7 is frequency, and the vertical axis is power. Note that since each communication slot 300 shown in Figure 6 is transmitted at a different time, the frequency spectrum shown in Figure 7 is a frequency spectrum of signals at different times.

Fig. 8 is a diagram showing an example of a frequency spectrum when the known signal shown in Fig. 6 is subjected to interference. The horizontal axis of Fig. 8 is frequency, and the vertical axis is power. An interference wave 302A interferes with communication slots of frequency channel indexes #1 to #7, and an interference wave 302B interferes with communication slots of frequency channel indexes #11 to #15. The other communication slots of frequency channel indexes #0, #8 to #10 are not affected by interference. Here, the interference wave 302A and the interference wave 302B are interference waves from different interference sources, and the interference wave 302A and the interference wave 302B do not have the same interference power, interference arrival angle, etc.

The method of determining the frequency channel group in the frequency channel group generation unit 205 will be explained using the example of the case where interference is present as shown in Figure 8.

The interference clustering unit 215 uses one or more of the SINR estimate, the interference power estimate, the interference angle estimate, and the interference complex signal estimate to group frequency channels based on the presence or absence of interference and the interference source. Specifically, the interference clustering unit 215 groups frequency channels that are interfered with and frequency channels that are not interfered with. Furthermore, the interference clustering unit 215 divides the frequency channels that are interfered with into groups for each interference source. The interference clustering unit 215 can perform grouping using, for example, clustering. Clustering is a method of grouping each data based on the similarity of the data, and corresponds to unsupervised learning in machine learning. Clustering includes hierarchical clustering and non-hierarchical clustering. Examples of hierarchical clustering include group average method and Ward's method. Examples of non-hierarchical clustering include k-means method. Here, the method used by the interference clustering unit 215 is not particularly limited.

8, if grouping is performed correctly, the frequency channels are divided into group #1 of frequency channel indexes #1 to #7, which is the group of interference wave 302A, group #2 of frequency channel indexes #11 to #15, which is the group of interference wave 302B, and group #3 of frequency channel indexes #0, #8 to #10, which is a group without interference. The interference clustering unit 215 outputs the grouping result to the frequency channel group determination unit 216.

The frequency channel group determination unit 216 determines a frequency channel group based on the grouping result by the interference clustering unit 215. Specifically, the frequency channel group determination unit 216 groups an interfered group and a non-interfered group into one group so that the frequency channels are adjacent to each other. If there are multiple patterns of grouping, the frequency channel group determination unit 216 selects a pattern that maximizes the number of frequency channels. Specifically, the frequency channel group determination unit 216 calculates the average value of the SINR estimate value of each group grouped by the interference clustering unit 215, and determines whether or not each group has interference based on the calculated average value. For example, if the average value of the SINR estimate value of the target group is equal to or less than a predetermined threshold value σ, the frequency channel group determination unit 216 determines that the target group is a group with "no interference", and if the average value of the SINR estimate value exceeds the threshold value σ, the frequency channel group determination unit 216 determines that the target group is a group with "interference". In the example shown in FIG. 8, group #1 and group #2 are determined to be groups with "interference", and group #3 is determined to be a group with "no interference".

Next, the frequency channel group determination unit 216 performs grouping such that the number of frequency channels is maximized when the frequency channels belonging to the "interference" group and the "no interference" group are grouped together so that the frequency channels are adjacent to each other. When it is expressed as "grouping the "interference" group and the "no interference" group together", it means that the group after grouping includes all the frequency channels belonging to the "interference" group and some or all the frequency channels belonging to the "no interference" group. In the example of FIG. 8, the groups generated by the interference clustering unit 215 are the "interference" group #1 with frequency channel indexes #1 to #7, the "interference" group #2 with frequency channel indexes #11 to #15, and the "no interference" group #3 with frequency channel indexes #0, #8 to #10. In this case, first, the "interference" group #1 and the frequency channels belonging to the "no interference" group #3 are grouped so that the frequency channels are adjacent to each other. In this case, the frequency channel indexes #0 to #10 can be grouped together, and the number of frequency channels is 11. Next, the frequency channels belonging to the group #2 with "interference" and the group #3 with "no interference" are grouped so that the frequency channels are adjacent to each other. In this case, the frequency channel indexes #8 to #15 can be grouped together, and the number of frequency channels is 8. In the example shown in FIG. 8, the number of frequency channels is greater when the group #1 and the frequency channels without interference are grouped together than when the group #2 and the frequency channels without interference are grouped together. In this case, the frequency channel group determination unit 216 determines the frequency channel group by setting the frequency channel indexes #0 to #10 as the frequency channel group #1 and the frequency channel indexes #11 to #15 as the frequency channel group #2, and outputs information indicating the determined frequency channel group to the interference suppression processing unit 206.

Note that grouping so that the frequency channels are "adjacent" means that the frequency channel indexes of the frequency channels belonging to the group after grouping are consecutive. Here, it is assumed that the frequency channel indexes are assigned in order of frequency magnitude. For example, when grouping the frequency channels belonging to the above group #2 and group #3, if frequency channel index #0 is grouped, the frequency channel indexes will not be consecutive, so frequency channel index #0 is excluded and frequency channel indexes #8 to #10 and #11 to #15 are grouped together to form a group of frequency channel indexes #8 to #15.

Next, we will explain the details of the interference suppression processing unit 206.

The interference suppression processing unit 206 generates an interference suppression weight for each frequency channel group generated by the frequency channel group generating unit 205, and performs interference suppression processing. Specifically, the interference suppression processing unit 206 generates an interference suppression weight for each of the generated multiple frequency channel groups, and performs interference suppression processing. The interference suppression processing unit 206 reads out the received signal belonging to the target frequency channel group from the received signal accumulation memory unit 203, and performs interference suppression processing using the received signal belonging to the target frequency channel group. Various methods of interference suppression processing are possible, and the method used by the interference suppression processing unit 206 is not limited to a specific method. For example, when the receiving device 20 has multiple receiving antennas, since the interference wave has spatial correlation between the receiving antennas, the interference suppression processing unit 206 can suppress the interference wave by multiplying the interference wave included in the received signal for each receiving antenna by a weight vector that makes the interference wave uncorrelated. First, the interference suppression processing unit 206 converts the received signal r(n) to be subjected to interference suppression into a frequency domain signal. Here, the received signal represented in the frequency domain for the receiving antenna number m and the subcarrier number k is R _m (k). The receiving antenna number m is an integer equal to or greater than 0 and less than the number of antennas M. The subcarrier number k is a number assigned to each of the frequency channel groups, and is an integer equal to or greater than 0 and less than the number of subcarriers _Nb . The interference suppression processor 206 can perform interference suppression processing on the received signal R _m (k) using the following formula (5).

Q _k is a received signal vector in the frequency domain after interference suppression for subcarrier number k, and is expressed as a matrix with M rows and 1 column as shown in the following formula (6): Q _m (k) in formula (6) is a received signal in the frequency domain after interference suppression for receiving antenna number m and subcarrier number k.

Furthermore, R _k is a received signal vector in the frequency domain before interference suppression for subcarrier number k, and is expressed as a matrix with M rows and 1 column, as shown in the following equation (7).

W _k is a weight vector for subcarrier number k, and is expressed as a matrix with M rows and M columns as shown in the following formula (8). _{W m1,m2} (k) is a weight signal corresponding to receiving antenna number m1 and receiving antenna m2 for suppressing interference present in a communication wave received at subcarrier number k. Each of m1 and m2 is an integer equal to or greater than 0 and less than M. Furthermore, W ^H _k represents the complex conjugate transpose of W _k .

The interference suppression processing unit 206 generates a weight vector W _k so as to satisfy the following equation (9): The weight vector W _k is an example of an interference suppression weight.

Here, G _k is the covariance matrix of the frequency domain signal B _m (k) of the interference wave for subcarrier number k, and I is a unit matrix with M rows and M columns. _{B m} (k) is the frequency domain signal of the interference wave of receiving antenna m and subcarrier number k. By using the weight vector W _k that satisfies equation (9) and performing interference suppression using equations (5) to (8), it is possible to convert to an interference wave that is uncorrelated between receiving antennas.

Next, we will explain the details of the frequency channel combining unit 207.

The frequency channel combining unit 207 performs a frequency channel combining process on the interference suppressed received signal in units of frequency channel groups. Here, the frequency channel combining unit 207 performs a combining process for each of a plurality of frequency channel groups . For example, the frequency channel combining unit 207 performs an inverse modulation process using a known signal on the received signal, which is a frequency domain signal that has been subjected to interference suppression, to estimate a channel frequency response for each frequency channel. Next, the frequency channel combining unit 207 combines the channel frequency responses of the frequency channels belonging to the target frequency channel group. At this time, since the initial phase of the channel frequency response differs for each frequency channel, the frequency channel combining unit 207 needs to match the initial phase for each frequency channel. As a method for matching the initial phase for each frequency channel, for example, a method described in Non-Patent Document 1 in which a wireless device other than the transmitting device 10 and the receiving device 20 is prepared and an initial phase is estimated may be used. In the above, the frequency channel group is generated so that the frequency channel indexes of the frequency channels belonging to the same frequency channel group are consecutive. However, if the frequency channel indexes are not consecutive, the frequency channel combining unit 207 may perform an interpolation process of the channel frequency response. For example, if the frequency channel indexes of a certain frequency channel group are #1, #3, and #4, there is no channel frequency response of the frequency channel index #2, so the frequency channel combining unit 207 uses the channel frequency responses of the frequency channel indexes #1 and #3 to interpolate the channel frequency response of the frequency channel index #2. By combining the channel frequency responses, a channel frequency response corresponding to the frequency bandwidth of the frequency channel group can be obtained. The frequency channel combining unit 207 applies IDFT (Inverse Division Fourier Transform) processing to the combined channel frequency response and converts it into a time domain signal, thereby obtaining the channel impulse response of the frequency channel group.

Figure 9 is a diagram showing an example of a channel impulse response. The horizontal axis of Figure 9 is time (samples), and the vertical axis is the power value of the channel impulse response. Here, the time for one sample corresponds to the inverse of the frequency bandwidth [Hz] when combined in a frequency channel group. Therefore, if the frequency bandwidth when combined is large, the time per sample of the channel impulse response becomes shorter. In other words, the time resolution of the channel impulse response becomes higher. The frequency channel combining unit 207 calculates and outputs the channel impulse response for each frequency channel group.

Here we will explain the details of the direct wave component extraction unit 208.

The direct wave component extraction unit 208 extracts direct wave components from the channel impulse response for each frequency channel group determined by the frequency channel combination unit 207. For example, the direct wave component extraction unit 208 can use a predetermined threshold value α for the channel impulse response shown in FIG. 9 as a reference and determine the smallest time sample index from the channel impulse response samples that exceed the threshold value α as the direct wave component. The direct wave component extraction unit 208 extracts only the channel impulse response with time index "0" that becomes the determined direct wave component. The direct wave component extraction unit 208 performs the above-mentioned process for each frequency channel group and outputs direct wave components for the number of frequency channel groups.

Next, we will explain the details of the radio wave arrival angle estimation unit 209.

The radio wave arrival angle estimation unit 209 estimates the arrival angle of the direct wave component as the radio wave arrival angle by using the direct wave component for each frequency channel group obtained by the direct wave component extraction unit 208. For example, the radio wave arrival angle estimation unit 209 can estimate the radio wave arrival angle β _j,a,b by using the following formula (10).

The radio wave arrival angle β _j,a,b is an estimated value of the radio wave arrival angle obtained from the channel impulse response between indexes a and b of the pair of receiving antennas in frequency channel group index j. Note that a and b are indexes of the pair of receiving antennas used for interference suppression, and a is a value different from b. The frequency channel group index j is an integer equal to or greater than 0 and less than the number N _g of frequency channel groups. ρ _j is a wavelength corresponding to the inverse of the frequency bandwidth after combination in frequency channel group index j, γ _j,a,b is a phase difference with respect to the channel impulse response between indexes a and b of the pair of receiving antennas in frequency channel group index j, and D _a,b is the interval between the pair of receiving antennas a and b. Note that the interval between the pair of receiving antennas a and b means the distance between the midpoint of the receiving antennas "1" and "2" and the midpoint of the receiving antennas "2" and "3" when the pair of receiving antennas a is the pair of receiving antennas "1" and "2" and the pair of receiving antennas b is the pair of receiving antennas "2" and "3".

If the symbol index of the known signal is p, the number of symbols of the known signal is N _p , the frequency channel group index is j, and the channel impulse response at symbol index p of index a of the receiving antenna set is S _j,a (p), the phase difference γ _j,a,b can be obtained by the following formula (11). The radio wave arrival angle estimation unit 209 estimates the radio wave arrival angle for each frequency channel group, and outputs the estimated radio wave arrival angle.

Next, we will explain the details of the arrival angle synthesis unit 210.

The arrival angle synthesis unit 210 synthesizes the estimation results of the radio wave arrival angle for each frequency channel group obtained by the radio wave arrival angle estimation unit 209. The arrival angle synthesis unit 210 can synthesize the estimation results of the radio wave arrival angle by using the SINR estimation value calculated by the interference measurement unit 204. Since the SINR estimation value is estimated for each frequency channel group, the arrival angle synthesis unit 210 can weight and synthesize the radio wave arrival angle estimation value according to the SINR estimation value. For example, assuming that a synthesis weight function G(x) obtained from x, an average value SINR _j of the SINR estimation value of the frequency channel group index j, and an average β _j of the radio wave arrival angle estimation value of the frequency channel group index j, are respectively, the radio wave arrival angle β after synthesis is expressed by the following formula (12). Note that the average value SINR j of the SINR estimation value of the frequency channel group index _j can be obtained by using formula (13), and the average β _j of the radio wave arrival angle estimation value of the frequency channel group index j can be obtained by using formula (14).

Here, _Fj represents a set of frequency channel indexes in frequency channel group index j, Y represents a set of receiving antenna indexes included in the receiving antenna pair in the interference suppression process, Z(a) represents a set of receiving antenna indexes that are pairs with receiving antenna index a included in the receiving antenna pair in the interference suppression process, and _Nh represents the number of receiving antenna pairs in the interference suppression process.

Furthermore, the composite weight function G(x) is expressed, for example, by the following equation (15).

Figure 10 is a flowchart for explaining the operation of the receiving device 20 according to the first embodiment. Since the details of each process have been described above, the process flow will be mainly explained here.

When the receiving antenna unit 200 of the receiving device 20 receives a signal from the transmitting device 10, the frequency conversion unit 201 performs a frequency conversion process (step S101). The receiving filter unit 202 performs a reception filtering process on the signal after the frequency conversion (step S102). The received signal after the reception filtering process is stored in the received signal storage memory unit 203 and is output to the interference measurement unit 204. The interference measurement unit 204 measures the state of interference contained in the received signal and generates interference information (step S103). The interference information is output to each of the frequency channel group generation unit 205 and the arrival angle synthesis unit 210.

The frequency channel group generation unit 205 generates a frequency channel group (step S104) and notifies the generated frequency channel group to the interference suppression processing unit 206. The interference suppression processing unit 206 performs interference suppression processing for each frequency channel group (step S105) and outputs the signal after the interference suppression processing to the frequency channel coupling unit 207.

The frequency channel combining unit 207 combines the frequency channels for each frequency channel group (step S106). The direct wave component extracting unit 208 extracts the direct wave component for each frequency channel group (step S107).

The radio wave arrival angle estimation unit 209 estimates the radio wave arrival angle for each frequency channel group (step S108) and outputs the number of radio wave arrival angle estimates for the number of frequency channel groups. The arrival angle synthesis unit 210 synthesizes the radio wave arrival angle estimates for each frequency channel group output by the radio wave arrival angle estimation unit 209 based on the interference information generated by the interference measurement unit 204 (step S109) and outputs the arrival angle estimation result.

As described above, the radio wave arrival angle estimation device 1 according to the first embodiment is a radio wave arrival angle estimation device that estimates the arrival direction of radio waves from a received signal that receives a signal transmitted using multiple frequency channels, and includes an interference measurement unit 204 that measures the state of interference for each frequency channel and generates interference information, a frequency channel group generation unit 205 that groups multiple frequency channels based on the interference information generated for each frequency channel to generate frequency channel groups, an interference suppression processing unit 206 that generates interference suppression weights for each frequency channel group and performs interference suppression processing, a frequency channel combination unit 207 that combines frequency channels for each frequency channel group for the signal after the interference suppression processing, a direct wave component extraction unit 208 that extracts direct wave components from the signal after the frequency channel combination, and a radio wave arrival angle estimation unit 209 that estimates the arrival angle of radio waves from the direct wave components. With this configuration, the radio wave arrival angle estimation device 1 performs interference suppression processing and frequency channel combination for each frequency channel group in which frequency channels are grouped based on the interference information for each frequency channel. Therefore, even if the interference state differs for each frequency channel, for example, when multiple interference sources exist, an interference suppression weight is generated for each frequency channel group according to the interference state, and the interference suppression process is performed using the generated interference suppression weight. Then, the frequency channels are combined for each frequency channel group for the signal after the interference suppression process. Therefore, when combining frequency channels, the frequency channels that have been subjected to the interference suppression process using a common interference suppression weight are combined, so that the frequency channels can be combined even for signals after the interference suppression process. Therefore, the interference suppression process reduces the influence of interference from other systems, and the combination of frequency channels can reduce the influence of multipath, so that the arrival angle of radio waves can be estimated with high accuracy even in an environment affected by both multipath and interference from other systems.

As a specific configuration of the radio wave arrival angle estimation device 1 according to the first embodiment, the interference suppression processing unit 206 generates an interference suppression weight for each of the multiple frequency channel groups and performs interference suppression processing, the frequency channel combining unit 207 combines the frequency channels for each frequency channel group, the direct wave component extraction unit 208 extracts the direct wave component for each frequency channel group, the radio wave arrival angle estimation unit 209 estimates the arrival angle for each frequency channel group, and further includes an arrival angle synthesis unit 210 that synthesizes the estimation results of the multiple arrival angles for each frequency channel group. As a result, the arrival angle of the radio wave is estimated for each of the multiple frequency channel groups, and the final estimation result is obtained by synthesizing the estimation results of the multiple arrival angles. Therefore, the arrival angle of the radio wave can be estimated with high accuracy.

Here, the interference measurement unit 204 can generate interference information including one or more estimated values of the signal-to-interference plus noise power ratio, the interference power, the interference arrival angle, and the interference complex signal. The frequency channel group generation unit 205 can generate a frequency channel group using one or more of the signal-to-interference plus noise power ratio, the interference power, the interference arrival angle, and the interference complex signal.

The frequency channel group generating unit 205 has an interference clustering unit 215 that groups frequency channels based on the presence or absence of interference and the interference source based on the interference information, and a frequency channel group determining unit 216 that determines a frequency channel group from the grouping result. More specifically, the interference clustering unit 215 divides the frequency channels into a group of frequency channels that are interfered with and a group of frequency channels that are not interfered with, and further groups the group of frequency channels that are interfered with by interference source, and the frequency channel group determining unit 216 determines a frequency channel group such that the number of frequency channels is maximized when the frequency channels belonging to the group that is interfered with and the group that is not interfered with are grouped into one group so that the frequency channels are adjacent to each other. This makes it possible to group frequency channels that are interfered with from different interference sources into different frequency channel groups, and makes it easier to perform frequency channel coupling on a frequency channel group basis.

According to the first embodiment, a radio wave arrival angle estimation method can be realized, which is executed by the radio wave arrival angle estimation device 1, which estimates the arrival direction of radio waves from a received signal that has been transmitted using multiple frequency channels. This radio wave arrival angle estimation method includes the steps of: measuring the state of interference for each frequency channel to generate interference information; grouping the multiple frequency channels to generate frequency channel groups based on the interference information generated for each frequency channel; generating interference suppression weights for each frequency channel group to perform interference suppression processing; extracting direct wave components from the signal after the interference suppression processing; and estimating the arrival angle of radio waves from the direct wave components.

Although not shown, the estimated result of the angle of arrival can be used for position estimation. In recent years, various services utilizing location information have been provided, and the demand for location information is increasing. For outdoor position estimation, a method using the Global Positioning System (GPS) is widely used. For indoor use or places where GPS cannot be used, position estimation techniques using wireless signals such as wireless LAN (Local Area Network), Bluetooth, and UWB (Ultra Wide Band) have been proposed. Position estimation techniques using wireless signals include AoA and AoD using the angle of arrival of radio waves, ToA (Time of Arrival) and TDoA (Time Difference of Arrival) using the arrival time of radio waves, and RSSI (Received Signal Strength Indication) using the strength of the received signal. For example, in Bluetooth, position estimation using RSSI was adopted until version 5.1, but from version 5.1 onwards, position estimation using AoA and AoD using the angle of arrival of radio waves has been adopted, and higher position estimation accuracy than RSSI is expected. Bluetooth location estimation is likely to be used indoors, but indoors, radio waves arrive after being reflected by walls and the like, so the receiving device is susceptible to multipath effects caused by direct waves and reflected waves. In a multipath environment, the accuracy of location estimation decreases. In addition, since Bluetooth and wireless LAN are both wireless communication standards that use unlicensed bands, they are likely to be affected by interference from other systems. For this reason, when used for indoor location estimation, a technology that can achieve both interference countermeasures and multipath countermeasures assuming the presence of multiple interference sources, as described above, is preferable.

Embodiment 2.
11 is a diagram showing a configuration of a receiving device 20A according to the second embodiment. Although not shown, the radio wave arrival angle estimation device 1A according to the second embodiment includes a receiving device 20A instead of the receiving device 20 of the first embodiment.

The receiving device 20A has a receiving antenna unit 200, a frequency conversion unit 201, a receiving filter unit 202, a received signal storage memory unit 203, an interference measurement unit 204, a frequency channel group generation unit 205, a frequency channel group selection unit 217, an interference suppression processing unit 206A, a frequency channel coupling unit 207A, a direct wave component extraction unit 208A, and a radio wave arrival angle estimation unit 209A. In other words, the receiving device 20A adds a frequency channel group selection unit 217 to the configuration of the receiving device 20, omits the arrival angle synthesis unit 210, and instead of the interference suppression processing unit 206, the frequency channel coupling unit 207, the direct wave component extraction unit 208, and the radio wave arrival angle estimation unit 209, it has an interference suppression processing unit 206A, a frequency channel coupling unit 207A, a direct wave component extraction unit 208A, and a radio wave arrival angle estimation unit 209A. Hereinafter, detailed description of functions common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

In the first embodiment, when the receiving device 20 generates frequency channel groups, it calculates multiple radio wave arrival angle estimates for each of all frequency channel groups, and generates an arrival angle estimation result by combining the multiple radio wave arrival angle estimates. In this case, as the number of frequency channel groups increases, the amount of processing increases. For this reason, in the second embodiment, one frequency channel group is first selected from the frequency channel groups, and processing is performed only for the selected frequency channel group.

The frequency channel group selection unit 217 selects one of the frequency channel groups generated by the frequency channel group generation unit 205. For example, the frequency channel group selection unit 217 can select a frequency channel group based on the number of frequency channels belonging to the frequency channel group. The frequency channel group selection unit 217 selects the frequency channel group with the largest number of frequency channels. A large number of frequency channels increases the time resolution of the channel impulse response, which is effective as a multipath countermeasure. However, the method of selecting a frequency channel group is not limited to the above example.

The processing of the interference suppression processing unit 206A, the frequency channel combining unit 207A, the direct wave component extraction unit 208A, and the radio wave arrival angle estimation unit 209A is the same as that of the interference suppression processing unit 206, the frequency channel combining unit 207, the direct wave component extraction unit 208, and the radio wave arrival angle estimation unit 209, respectively, except that processing is performed only for the selected frequency channel group. In this case, the radio wave arrival angle estimation unit 209 calculates an estimate of one radio wave arrival angle, so this estimate is output as the arrival angle estimation result, and arrival angle synthesis processing is not required.

Figure 12 is a flowchart for explaining the operation of the receiving device 20A in embodiment 2. Steps S101 to S104 are the same as those in embodiment 1, so the explanation is omitted.

When the frequency channel groups are generated by the frequency channel group generation unit 205, the frequency channel group selection unit 217 selects one of the frequency channel groups (step S201). The interference suppression processing unit 206A performs interference suppression processing of the selected frequency channel group (step S202). The frequency channel coupling unit 207A performs frequency channel coupling processing of the selected frequency channel group (step S203).

The direct wave component extraction unit 208A extracts the direct wave components of the selected frequency channel group (step S204). The radio wave arrival angle estimation unit 209A performs an arrival angle estimation process for the radio waves of the selected frequency channel group (step S205).

As described above, according to the second embodiment, the same effect as that of the first embodiment can be achieved. Also, according to the second embodiment, the receiving device 20A further includes a frequency channel group selection unit 217 that selects a frequency channel group to be processed from the generated frequency channel groups, and each of the interference suppression processing unit 206A, the frequency channel coupling unit 207A, the direct wave component extraction unit 208A, and the radio wave arrival angle estimation unit 209A processes the selected frequency channel group and does not process the unselected frequency channel group. This makes it possible to reduce the amount of processing required for the arrival angle estimation compared to the first embodiment. In particular, when the number of frequency channel groups generated by the frequency channel group generation unit 205 increases, the effect of reducing the amount of processing is enhanced.

The frequency channel group selection unit 217 can select a frequency channel group based on the number of frequency channels belonging to the frequency channel group. For example, a frequency channel group with the largest number of frequency channels can be selected as the processing target. The greater the number of frequency channels, the higher the time resolution of the channel impulse response, making it more effective as a multipath countermeasure.

Embodiment 3.
The radio wave arrival angle estimation device 1B according to the third embodiment includes the transmitting device 10 shown in FIG. 2 and the receiving device 20A shown in FIG. 11. However, the frequency hopping sequence used by the frequency conversion unit 103 of the transmitting device 10 is different from that of the first and second embodiments. In the first and second embodiments, a known signal is transmitted according to a frequency hopping sequence having a random frequency hopping pattern as shown in FIG. 6. For this reason, when the receiving device 20A according to the second embodiment performs frequency coupling, the coupling process is performed on the frequency channels included in the frequency channel group to be processed, and therefore the frequency coupling process cannot be performed until the target frequency channels are all available. For this reason, in the third embodiment, a frequency hopping sequence is used in which the frequency channels belonging to the frequency channel group to be processed are preferentially transmitted in advance, so that the frequency coupling process can be started early.

Figure 13 is a diagram showing a known signal transmitted in the third embodiment. The known signal is transmitted as a communication slot 400 using 16 frequency channels with frequency channel indexes #0 to #15. Here, a frequency channel group #1 consisting of frequency channels with frequency channel indexes #0 to #10 and a frequency channel group #2 consisting of frequency channels with frequency channel indexes #11 to #15 are generated. At this time, since the frequency channel group #1 has a larger number of frequency channels than the frequency channel group #2, the frequency channel group selection unit 217 of the receiving device 20A selects the frequency channel group #1. In this case, the frequency conversion unit 103 performs frequency conversion processing according to a frequency hopping sequence in which the frequency hopping is performed randomly among the frequency channels with frequency channel indexes #0 to #10 belonging to the frequency channel group #1, and after the frequency hopping of the frequency channel group #1 is completed, the frequency conversion processing is performed randomly among the frequency channels with frequency channel indexes #11 to #15 belonging to the frequency channel group #2. A sequence indicating a frequency hopping sequence is called a frequency hopping sequence. For example, the frequency hopping sequences used by the frequency conversion unit 103 are #0, #2, #4, #6, #8, #10, #1, #3, #5, #7, #9, #11, #13, #15, #12, and #14 in the example shown in FIG. 13. As a result, the frequency channels belonging to the frequency channel group #1 are transmitted before the frequency channels belonging to the frequency channel group #2, and in the example of FIG. 13, at the time of receiving the frequency channel of the frequency channel index #9, the receiving device 20A can start the frequency coupling process of the frequency channel group #1. In the third embodiment, the frequency channels belonging to the frequency channel group #1 are prepared in the receiving device 20B earlier than when the frequency hopping sequence not based on the frequency channel group as shown in FIG. 6 is used. Therefore, the frequency coupling process of the frequency channel group #1 can be started earlier than in the second embodiment, and as a result, the arrival angle estimation result can be obtained earlier than in the second embodiment.

As described above, according to the third embodiment, the radio wave arrival angle estimation device 1B includes a frequency conversion unit 103 that converts the frequency of a signal to be transmitted from among a plurality of frequency channels by a frequency hopping method to match the frequency channel to be transmitted, and the frequency conversion unit 103 switches the frequency channel to be transmitted in a switching pattern based on the frequency channel group generated by the frequency channel group generation unit 205 of the receiving device 20A. More specifically, the frequency conversion unit 103 switches the frequency channel to be transmitted so that the frequency channel belonging to the frequency channel group selected by the frequency channel group selection unit 217 is transmitted prior to the frequency channels belonging to the other frequency channel groups. This provides the same effects as the first and second embodiments, and allows the arrival angle estimation result to be obtained earlier than the second embodiment.

Next, the hardware configuration of the radio wave arrival angle estimation devices 1, 1A, and 1B according to the first to third embodiments will be described. Each part of the radio wave arrival angle estimation devices 1, 1A, and 1B is realized by a processing circuit. These processing circuits may be realized by dedicated hardware or may be a control circuit using a CPU (Central Processing Unit).

When the above processing circuits are realized by dedicated hardware, they are realized by the processing circuit 90 shown in FIG. 14. FIG. 14 is a diagram showing dedicated hardware for realizing the functions of the radio wave arrival angle estimation devices 1, 1A, and 1B according to embodiments 1 to 3. 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 of these.

When the above 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. 15. FIG. 15 is a diagram showing the configuration of the control circuit 91 for realizing the functions of the radio wave arrival angle estimation device 1, 1A, 1B according to the first to third embodiments. As shown in FIG. 15, the control circuit 91 includes a processor 92 and a memory 93. The processor 92 is a CPU, and is also called an arithmetic device, 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 RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (registered trademark) (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disk), etc.

When the above processing circuit is realized by the control circuit 91, the processor 92 reads and executes a program corresponding to the processing of each component stored in the memory 93. The program executed by the processor 92 may be provided in a state stored in a storage medium, or may be provided via a communication path such as the Internet. The memory 93 is also used as a temporary memory for each process executed by the processor 92. The functions of the radio wave arrival angle estimation devices 1, 1A, and 1B according to the first to third embodiments may be realized by combining the processing circuit 90, which is dedicated hardware, and the control circuit 91 using a CPU. The division of the functional units illustrated in the above embodiment is an example, and the function shown in one functional unit may be realized by multiple processing circuits, or the function shown in multiple functional units may be realized by multiple processing circuits.

As described above, according to the first to third embodiments, a control circuit 91 can be realized that controls the radio wave arrival angle estimation device 1, 1A, 1B that estimates the arrival direction of radio waves from a received signal that has been transmitted using multiple frequency channels. The control circuit 91 causes the radio wave arrival angle estimation device 1, 1A, 1B to execute the steps of: measuring the interference state for each frequency channel and generating interference information; grouping the multiple frequency channels based on the interference information generated for each frequency channel to generate frequency channel groups; generating interference suppression weights for each frequency channel group to perform interference suppression processing; extracting direct wave components from the signal after the interference suppression processing; and estimating the arrival angle of radio waves from the direct wave components.

Furthermore, according to the first to third embodiments, a storage medium can be realized that stores a program for controlling the radio wave arrival angle estimation device 1, 1A, 1B that estimates the arrival direction of radio waves from a received signal that has been transmitted using multiple frequency channels. The program stored in the storage medium causes the radio wave arrival angle estimation device 1, 1A, 1B to execute the steps of: measuring the interference state for each frequency channel and generating interference information; grouping the multiple frequency channels based on the interference information generated for each frequency channel to generate frequency channel groups; generating interference suppression weights for each frequency channel group to perform interference suppression processing; extracting direct wave components from the signal after the interference suppression processing; and estimating the arrival angle of radio waves from the direct wave components.

The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the spirit of the invention.

For example, in the second embodiment, the frequency channel group selection unit 217 selects one frequency channel group, but multiple frequency channel groups may be selected as long as the number is less than the number of generated frequency channel groups. For example, when three or more frequency channel groups are generated, two frequency channel groups may be selected from the frequency channel group having the largest number of frequency channels. In this case, the arrival angle estimation device 1B includes the receiving device 20 according to the first embodiment, and, as in the first embodiment, the interference suppression processing unit 206, the frequency channel combining unit 207, the direct wave component extraction unit 208, and the radio wave arrival angle estimation unit 209 process each of the selected multiple frequency channel groups, and the arrival angle synthesis unit 210 performs synthesis processing.

It is also possible to realize only some of the functions of the radio wave arrival angle estimation devices 1, 1A, and 1B without having all of the functions described in each of the above embodiments. In this case, for example, a device having only the functions of the receiving devices 20 and 20A may be referred to as a "radio wave arrival angle estimation device."

1, 1A, 1B Radio wave arrival angle estimation device, 10 Transmitting device, 20, 20A Receiving device, 90 Processing circuit, 91 Control circuit, 92 Processor, 93 Memory, 100 Known signal generation unit, 101 Modulation unit, 102 Transmission filter unit, 103, 201 Frequency conversion unit, 104 Transmitting antenna unit, 200 Receiving antenna unit, 202 Receiving filter unit, 203 Received signal storage memory unit, 204 Interference measurement unit, 205 Frequency channel group generation unit, 206, 206A Interference suppression processing unit, 207, 207A Frequency channel combination unit, 208, 208A Direct wave component extraction unit, 209, 209A Radio wave arrival angle estimation unit, 210 Arrival angle synthesis unit, 211 SINR estimation unit, 212 Interference power estimation unit, 213 Interference arrival angle estimation unit, 214 Interference complex signal estimation unit, 215 interference clustering unit, 216 frequency channel group determination unit, 217 frequency channel group selection unit, 300, 400 communication slots, 301 signal, 302A, 302B interference waves.

Claims (14)

A radio wave arrival angle estimation device that estimates an arrival direction of a radio wave from a received signal that is received using a plurality of frequency channels,
an interference measurement unit that measures an interference state for each of the frequency channels and generates interference information;
a frequency channel group generation unit that generates a frequency channel group by grouping the plurality of frequency channels based on the interference information generated for each of the frequency channels;
an interference suppression processing unit that generates an interference suppression weight for each frequency channel group and performs interference suppression processing;
a frequency channel combining unit that combines the frequency channels in units of the frequency channel group for the signal after the interference suppression processing;
a direct wave component extraction unit that extracts a direct wave component from the signal obtained by combining the frequency channels;
a radio wave arrival angle estimating unit that estimates an arrival angle of a radio wave from the direct wave component;
A radio wave arrival angle estimation device comprising: the interference suppression processing unit generates the interference suppression weight for each of the plurality of frequency channel groups and performs the interference suppression processing;
The frequency channel combining unit combines the frequency channels for each of the frequency channel groups,
The direct wave component extraction unit extracts a direct wave component for each of the frequency channel groups,
the radio wave arrival angle estimation unit estimates the arrival angle for each of the frequency channel groups;
an arrival angle synthesis unit that synthesizes the estimation results of the plurality of arrival angles for each of the frequency channel groups;
The radio wave arrival angle estimation device according to claim 1 , further comprising: a frequency channel group selection unit that selects the frequency channel group to be processed from the generated frequency channel group;
Further equipped with
2. The radio wave arrival angle estimation device according to claim 1, wherein each of the interference suppression processing unit, the frequency channel combining unit, the direct wave component extraction unit, and the radio wave arrival angle estimation unit performs processing on the selected frequency channel group and does not perform processing on the unselected frequency channel group. The radio wave arrival angle estimation device according to claim 3, characterized in that the frequency channel group selection unit selects a frequency channel group based on the number of frequency channels belonging to the frequency channel group. The radio wave arrival angle estimation device according to any one of claims 1 to 4, characterized in that the interference measurement unit generates the interference information including one or more estimated values of a signal-to-interference-plus-noise power ratio, an interference power, an interference arrival angle, and an interference complex signal. 5. The radio wave arrival angle estimation device according to claim 1, wherein the frequency channel group generation unit generates the frequency channel group using one or more of a signal-to-interference- plus -noise power ratio, an interference power, an interference arrival angle, and an interference complex signal. The frequency channel group generation unit
an interference clustering unit that groups the frequency channels based on the presence or absence of interference and an interference source based on the interference information;
a frequency channel group determination unit that determines the frequency channel group based on the result of the grouping;
The radio wave arrival angle estimation device according to any one of claims 1 to 4 , further comprising: The interference clustering unit divides the frequency channels into a group of interfered frequency channels and a group of not interfered frequency channels, and further divides the group of interfered frequency channels into groups for each interference source;
8. The radio wave arrival angle estimation device according to claim 7, wherein the frequency channel group determination unit determines the frequency channel group such that a number of frequency channels is maximized when the group experiencing interference and the frequency channels belonging to the group not experiencing interference are grouped together such that the frequency channels are adjacent to each other. a frequency conversion unit that converts the frequency of the signal to be transmitted according to the frequency channel to be transmitted from among a plurality of the frequency channels by a frequency hopping method;
The radio wave arrival angle estimation device according to any one of claims 1 to 4 , further comprising: a frequency conversion unit that converts the frequency of the signal to be transmitted according to the frequency channel to be transmitted among the plurality of frequency channels by a frequency hopping method;
Further equipped with
4. The radio wave arrival angle estimation device according to claim 3, wherein the frequency conversion unit switches the frequency channel to be transmitted in a switching pattern based on the frequency channel group generated by the frequency channel group generation unit. The radio wave arrival angle estimation device according to claim 10, characterized in that the frequency conversion unit switches the frequency channel to be transmitted so that the frequency channel belonging to the frequency channel group selected by the frequency channel group selection unit is transmitted prior to the frequency channels belonging to the other frequency channel groups. A radio wave arrival angle estimation method executed by a radio wave arrival angle estimation device that estimates an arrival direction of a radio wave from a received signal that is received using a plurality of frequency channels, comprising:
measuring an interference state for each of the frequency channels to generate interference information;
generating a frequency channel group by grouping the plurality of frequency channels based on the interference information generated for each of the frequency channels;
generating an interference suppression weight for each frequency channel group and performing an interference suppression process;
extracting a direct wave component from the signal after the interference suppression processing;
estimating an angle of arrival of radio waves from the direct wave component;
A radio wave arrival angle estimation method comprising: A control circuit for controlling a radio wave arrival angle estimation device that estimates an arrival direction of a radio wave from a received signal that has been transmitted using a plurality of frequency channels, comprising:
measuring an interference state for each of the frequency channels to generate interference information;
generating a frequency channel group by grouping the plurality of frequency channels based on the interference information generated for each of the frequency channels;
generating an interference suppression weight for each frequency channel group and performing an interference suppression process;
extracting a direct wave component from the signal after the interference suppression processing;
estimating an angle of arrival of radio waves from the direct wave component;
The control circuit causes the radio wave arrival angle estimation device to execute the above. A storage medium storing a program for controlling a radio wave arrival angle estimation device that estimates an arrival direction of a radio wave from a received signal that has been transmitted using a plurality of frequency channels, the program comprising:
measuring an interference state for each of the frequency channels to generate interference information;
generating a frequency channel group by grouping the plurality of frequency channels based on the interference information generated for each of the frequency channels;
generating an interference suppression weight for each frequency channel group and performing an interference suppression process;
extracting a direct wave component from the signal after the interference suppression processing;
estimating an angle of arrival of radio waves from the direct wave component;
The radio wave arrival angle estimation device according to claim 1,

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