Sensing apparatus, method for sensing, and program

Abstract

To provide a sensing apparatus capable of performing biological sensing with reduced energy consumption.SOLUTION: A sensing apparatus 100 includes: an acquisition unit 120 for sequentially acquiring an RSSI (Received Signal Strength Indicator) of a first wireless signal using Wi-Fi, the first wireless signal being received by a first wireless device 110 arranged in a target space 500; and a determination unit 130 for determining whether a living body 400 is present in the target space 500 on the basis of fluctuation of the RSSI.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a sensing device, a sensing method, and a program for performing accurate sensing of a living body. [Background technology]

[0002] Methods using radio signals are being considered as a method for determining the location of a person, etc. For example, Patent Document 1 discloses a technology for estimating the location and state of a person to be detected by analyzing components including Doppler shift using differential calculations. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-117972 Summary of the Invention [Problem to be solved by the invention]

[0004] With conventional methods, it is difficult to perform biological sensing with less energy consumption.

[0005] The present disclosure has been made in consideration of the above circumstances, and provides a sensing device and the like that can perform biological sensing with less energy consumption. [Means for solving the problem]

[0006] A sensing device according to one embodiment of the present disclosure includes an acquisition unit that sequentially acquires the RSSI (Received Signal Strength Indicator) of a first wireless signal via Wi-Fi received by a first wireless device placed in a target space, and a determination unit that determines whether a living body is present in the target space based on fluctuations in the RSSI.

[0007] A sensing device according to another aspect of the present disclosure includes an acquisition unit that sequentially acquires the RSSI of a first wireless signal, the first wireless signal being a 2.4 GHz band Wi-Fi signal received by a first wireless device placed in a target space, and a control unit that, when fluctuations in the RSSI exceed a predetermined threshold, causes the first wireless device to receive a second wireless signal from a second wireless device for a certain period of time, thereby sensing a living body in the target space based on first CSI (Channel State Information) based on the second wireless signal.

[0008] A sensing device according to another aspect of the present disclosure includes a control unit that senses a living body in a target space based on CSI based on a first wireless signal transmitted by Wi-Fi for a second wireless device by causing a first wireless device placed in the target space to receive the wireless signal for a certain period of time.

[0009] These general or specific aspects may be realized as a system, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized as any combination of an apparatus, a system, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0010] According to the sensing device and the like according to the present disclosure, it is possible to perform sensing of a living body with less energy consumption. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram for explaining an outline of a sensing system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of the sensing device according to the embodiment. [Figure 3] FIG. 3 is a diagram for explaining the relationship between a transmission signal, a channel, and a reception signal. [Figure 4]FIG. 4 is a diagram for explaining the propagation characteristic H at each timing. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of the second radio device according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of the configuration of the third radio device according to the embodiment. [Figure 7] FIG. 7 is a flowchart illustrating an example of a sensing method performed by the sensing device according to the embodiment. [Figure 8] FIG. 8 is a flowchart showing another example of the sensing method performed by the sensing device according to the embodiment. [Figure 9] FIG. 9 is a flowchart showing an example of a sensing method by the sensing device according to the first modification. [Figure 10] FIG. 10 is a flowchart showing an example of a sensing method by the sensing device according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Findings that formed the basis of this disclosure) As a method for sensing a living body, a method using a radio signal is being considered.

[0013] In conventional technologies such as Patent Document 1, a transmitting device that transmits a wireless signal and a receiving device that receives a wireless signal perform biometric sensing on the premise of acquiring CSI (Channel State Information), and there is no description of countermeasures for situations where sensing can be simplified, such as in unmanned conditions, making it difficult to perform biometric sensing with less energy consumption.

[0014] Therefore, the present inventors have come up with a sensing device that can perform biological sensing with less energy consumption.

[0015] A sensing device according to a first aspect of the present disclosure includes an acquisition unit that sequentially acquires a Received Signal Strength Indicator (RSSI) of a first wireless signal via Wi-Fi received by a first wireless device placed in a target space, and a determination unit that determines whether a living body is present in the target space based on fluctuations in the RSSI.

[0016] For example, by using fluctuations in the received signal strength indicator (RSSI) of a beacon signal when the beacon signal that consumes less energy is received, it may be possible to perform biological sensing with less energy consumption.

[0017] A sensing device according to a second aspect of the present disclosure includes an acquisition unit that sequentially acquires the RSSI of a first wireless signal, the first wireless signal being a 2.4 GHz band Wi-Fi signal received by a first wireless device placed in a target space, and a control unit that, when fluctuations in the RSSI exceed a predetermined threshold, causes the first wireless device to receive a second wireless signal from a second wireless device for a certain period of time, thereby sensing a living body in the target space based on first CSI (Channel State Information) based on the second wireless signal.

[0018] According to this, when the fluctuation of RSSI exceeds a predetermined threshold, biological sensing is performed using the second wireless signal transmitted from the second wireless device. Therefore, when there is a high possibility that a biological organism is present in the target space, biological sensing can be performed using, for example, the second wireless signal, which consumes more energy during reception than the first wireless signal and can obtain highly accurate sensing results. Therefore, when there is a low possibility that a biological organism is present in the target space, biological sensing using the second wireless signal, which consumes more energy, can be reduced, and biological sensing can be performed with less energy consumption.

[0019] A sensing device according to a third aspect of the present disclosure is a sensing device according to the second aspect, further comprising a determination unit that determines that a living body is present in the target space when the fluctuation in the RSSI of the first wireless signal received by the first wireless device exceeds a predetermined threshold.

[0020] Therefore, when it is determined that a living body is not present in the target space, sensing of the living body using the second wireless signal, which requires more energy consumption, can be suppressed, and sensing of the living body can be performed with less energy consumption.

[0021] A sensing device according to a fourth aspect of the present disclosure is a sensing device according to the second or third aspect, wherein the first radio device is a slave device in Wi-Fi wireless communication, and the second radio device is a master device in Wi-Fi wireless communication.

[0022] A sensing device according to a fifth aspect of the present disclosure is a sensing device according to any one of the second to fourth aspects, wherein the control unit further performs sensing of a living body in the target space based on a second CSI based on the third radio signal and the first CSI when a third radio signal transmitted from a third radio device for the second radio device is received by the first radio device.

[0023] Therefore, sensing of a living body in the target space is performed based on the second CSI based on the third wireless signal from the third wireless device, and sensing of a living body in the target space is performed based on the first CSI based on the second wireless signal from the second wireless device, thereby enabling more accurate sensing of the living body.

[0024] A sensing device according to a sixth aspect of the present disclosure is a sensing device according to any one of the second to fifth aspects, wherein the first radio signal is a beacon signal and the second radio signal is a multicarrier signal.

[0025] According to this, when it is determined that there is a high possibility that a living organism is present in the target space using a beacon signal that can be received with less energy consumption, it is possible to perform sensing of the living organism using a multicarrier signal that consumes more energy than a beacon signal when receiving and that can obtain highly accurate sensing results. Therefore, when there is a low possibility that a living organism is present in the target space, it is possible to reduce the number of times that sensing of the living organism is performed using the second wireless signal that requires more energy consumption, and it is possible to perform sensing of the living organism with less energy consumption.

[0026] A sensing device according to a seventh aspect of the present disclosure is a sensing device according to any one of the second to sixth aspects, wherein the greater the variation in the RSSI, the greater the amount of activity of the living organism present in the target space, and the predetermined threshold indicates that the amount of activity of the living organism is a predetermined amount of activity.

[0027] According to this, when the variation in RSSI exceeds a predetermined threshold and the activity amount of a living organism present in the target space is greater than a predetermined activity amount, sensing of the living organism is performed using the second wireless signal transmitted from the second wireless device. When the activity amount of a living organism present in the target space is greater than a predetermined activity amount, it is highly likely that the living organism is present in the target space. Therefore, when there is a high possibility that the living organism is present in the target space, it is possible to perform sensing of the living organism using, for example, the second wireless signal, which consumes more energy when receiving than the first wireless signal and can obtain highly accurate sensing results. Therefore, when there is a low possibility that the living organism is present in the target space, it is possible to reduce the frequency of sensing of the living organism using the second wireless signal, which requires more energy consumption, and it is possible to perform sensing of the living organism with less energy consumption.

[0028] A sensing device according to an eighth aspect of the present disclosure is a sensing device according to any one of the second to seventh aspects, wherein the control unit, when a predetermined condition is further satisfied, causes the first radio device to receive the second radio signal for a certain period of time, thereby sensing a living body in the target space based on first CSI based on the second radio signal.

[0029] Therefore, the condition for performing biological sensing using the second wireless signal transmitted from the second wireless device can be limited to when the fluctuation in RSSI exceeds a predetermined threshold or when a predetermined condition is satisfied.

[0030] A sensing device according to a ninth aspect of the present disclosure is a sensing device according to any one of the second to eighth aspects, wherein when the fluctuation exceeds the predetermined threshold, the control unit causes the second radio to transmit a fourth radio signal to the first radio, thereby causing the first radio to receive the second radio signal for a certain period of time.

[0031] Therefore, by causing the first radio device to transmit the fourth radio signal, it is possible to receive, for example, the second radio signal transmitted from the second radio device as a response to the fourth radio signal.

[0032] A sensing device according to a tenth aspect of the present disclosure is the sensing device according to the ninth aspect, wherein the fourth wireless signal includes a ping, a null, and an NDP (None Data Packet).

[0033] A sensing device according to an eleventh aspect of the present disclosure includes a control unit that senses living organisms in a target space based on CSI based on a first wireless signal transmitted by Wi-Fi and transmitted from a third wireless device for a second wireless device by causing a first wireless device placed in the target space to receive the wireless signal for a certain period of time.

[0034] Therefore, by receiving the wireless signal transmitted from the third wireless device for the second wireless device without causing the first wireless device to perform transmission, it is possible to sense living organisms in the target space, thereby enabling sensing of living organisms with less energy consumption.

[0035] A sensing method according to a twelfth aspect of the present disclosure sequentially acquires the RSSI (Received Signal Strength Indicator) of a first wireless signal via Wi-Fi received by a first wireless device placed in a target space, and determines whether a living body is present in the target space based on fluctuations in the RSSI.

[0036] For example, by using the fluctuation in the RSSI of a beacon signal when the beacon signal that consumes less energy is received, it may be possible to perform biological sensing with less energy consumption.

[0037] A sensing method according to a thirteenth aspect of the present disclosure sequentially acquires the RSSI of a first wireless signal received by a first wireless device placed in a target space, the first wireless signal being a 2.4 GHz band Wi-Fi signal, and when fluctuations in the RSSI exceed a predetermined threshold, acquires first CSI (Channel State Information) based on the second wireless signal by having the first wireless device receive a second wireless signal from a second wireless device for a certain period of time, and performs sensing of a living body in the target space based on the first CSI.

[0038] According to this, when the fluctuation of RSSI exceeds a predetermined threshold, biological sensing is performed using the second wireless signal transmitted from the second wireless device. Therefore, when there is a high possibility that a biological organism is present in the target space, biological sensing can be performed using, for example, the second wireless signal, which consumes more energy during reception than the first wireless signal and can obtain highly accurate sensing results. Therefore, when there is a low possibility that a biological organism is present in the target space, biological sensing using the second wireless signal, which consumes more energy, can be reduced, and biological sensing can be performed with less energy consumption.

[0039] A sensing method according to a fourteenth aspect of the present disclosure involves having a first wireless device placed in a target space receive a first wireless signal via Wi-Fi, the wireless signal being transmitted from a third wireless device for a second wireless device, for a certain period of time, thereby obtaining CSI based on the wireless signal, and sensing a living body in the target space based on the CSI.

[0040] Therefore, by receiving the wireless signal transmitted from the third wireless device for the second wireless device without causing the first wireless device to perform transmission, it is possible to sense living organisms in the target space, thereby enabling sensing of living organisms with less energy consumption.

[0041] A program according to a fifteenth aspect of the present disclosure is a program for causing a computer to execute the sensing method according to any one of the twelfth to fourteenth aspects.

[0042] The present disclosure may be realized not only as an apparatus, but also as an integrated circuit including the processing means of such an apparatus, as a method in which the processing means constituting the apparatus have steps, as a program that causes a computer to execute those steps, or as information, data, or signals indicating the program.These programs, information, data, and signals may be distributed via recording media such as CD-ROMs or communication media such as the Internet.

[0043] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a preferred specific example of the present disclosure. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present disclosure will be described as optional components that constitute a more preferred embodiment. Note that in this specification and drawings, components having substantially the same functional configuration will be assigned the same reference numerals to avoid redundant description.

[0044] (Embodiment) In the embodiment, a method of sensing a living body will be described for a MIMO (Multiple-Input Multiple-Output) system in which both transmitting and receiving antennas are multiple. The method can also be applied to a SIMO (Single-Input Multiple-Output) system or a MISO (Multiple-Input Single-Output) system in which either transmitting or receiving antennas are multiple, and a SISO (Single-Input Single-Output) system in which either transmitting or receiving antennas is single.

[0045] [composition] FIG. 1 is a diagram for explaining an outline of a sensing system according to an embodiment.

[0046] 1 shows a sensing device 100, a second radio device 200, a third radio device 300, and a living body 400. For example, a sensing system 1 includes the sensing device 100, the second radio device 200, and the third radio device 300 among these.

[0047] The sensing device 100 is, for example, a device that is placed in a target space 500 and is capable of wireless communication via Wi-Fi (registered trademark). The sensing device 100 transmits and receives wireless signals to and from at least a second wireless device 200. The sensing device 100 may transmit and receive wireless signals to and from a third wireless device 300. The target space 500 is a space in which sensing of a living body 400 is possible using at least two devices among the sensing device 100, the second wireless device 200, and the third wireless device 300, and is a space that is the target of the sensing. Specifically, the sensing device 100 is a home appliance capable of wireless communication and is a slave device in Wi-Fi wireless communication. The sensing device 100 is, for example, a refrigerator. The sensing device 100 is not limited to a refrigerator, but may also be any home appliance capable of wireless communication via Wi-Fi, such as a microwave oven, a rice cooker, an induction cooking heater, an air conditioner, a lighting device, a television, or a recorder. The sensing device 100 does not have to be a home appliance, and may be a mobile terminal such as a smartphone, as long as it is a device capable of wireless communication.

[0048] The second wireless device 200 is placed in the target space 500 and is a device capable of wireless communication via Wi-Fi. The second wireless device 200 transmits and receives wireless signals to and from the sensing device 100 or the third wireless device 300. Specifically, the second wireless device 200 is a master device (access point) in Wi-Fi wireless communication. The second wireless device 200 is, for example, a router. The second wireless device 200 may be a mobile terminal such as a smartphone.

[0049] The third wireless device 300 is placed in the target space 500 and is a device capable of wireless communication via Wi-Fi. The third wireless device 300 transmits and receives wireless signals to and from the second wireless device 200. The third wireless device 300 may transmit and receive wireless signals to and from the sensing device 100. Specifically, the third wireless device 300 is a home appliance capable of wireless communication and is a slave device in Wi-Fi wireless communication. The third wireless device 300 is, for example, a rice cooker. The third wireless device 300 is not limited to a rice cooker, but may also be a microwave oven, refrigerator, induction cooking heater, air conditioner, lighting equipment, television, recorder, or other home appliance capable of wireless communication via Wi-Fi. The third wireless device 300 may also be a mobile terminal such as a smartphone.

[0050] Note that home appliances with wireless functions such as the sensing device 100 and the third wireless device 300 may use power supplied from a commercial power source or power from a battery for wireless communication. Even when the power is off or when power is not being supplied from the commercial power source, such home appliances may be supplied with power from a battery so that wireless communication with the second wireless device 200 is possible. The battery may be a primary battery or a secondary battery.

[0051] In the sensing system 1, the second radio device 200 transmits a wireless signal to the sensing device 100. When transmitting the wireless signal, the second radio device 200 emits radio waves based on the radio signal into the target space 500. The radio waves emitted into the target space 500 are reflected by a living organism 400 in the target space 500. The sensing device 100 receives radio waves including the radio waves reflected by the living organism 400, and senses the living organism 400 based on the received radio waves. Sensing the living organism 400 includes detecting the position of the living organism 400 in the target space 500, identifying the living organism 400, determining whether the living organism 400 is present in the target space 500, specifying the movement of the living organism 400, and specifying the posture of the living organism 400. When determining the position of the living body 400 in the target space 500, the total distance between the sensing device 100 and the living body 400 and the distance between the living body 400 and the second radio device 200 may be calculated, or the direction (angle) of the living body 400 relative to the sensing device 100 may be determined, or the direction (angle) of the living body 400 relative to the second radio device 200 may be determined.

[0052] Similarly, in the sensing system 1, a wireless signal transmitted by the third wireless device 300 for the second wireless device 200 may be received by the sensing device 100. Receiving a wireless signal transmitted for another wireless device in this manner is also called eavesdropping. The sensing device 100 can receive a wireless signal transmitted for another wireless device as long as it is in the same band and the same channel as the transmitted wireless signal. The received wireless signal is normally filtered before being used, but the sensing device 100 does not need to filter it in order to use it for sensing the living body 400.

[0053] When transmitting a wireless signal, the third wireless device 300 emits radio waves based on the wireless signal into the target space 500. The radio waves emitted into the target space 500 are reflected by a living organism 400 in the target space 500. The sensing device 100 receives radio waves including the radio waves reflected by the living organism 400, and determines whether the living organism 400 is present in the target space 500 or senses the living organism 400 based on the received radio waves. The determination of whether the living organism 400 is present in the target space 500 is performed based on RSSI. The RSSI used here may be a value included in a beacon reception signal, or a value included in CSI. Furthermore, sensing of the living organism 400 is performed based on CSI. The CSI includes various header information such as a packet type, a channel number, a sending address, a receiving address, a transfer rate, and a timestamp, as well as RSSI and a complex transfer function representing propagation characteristics H. The sensing of the living organism 400 includes detecting the position of the living organism 400 in the target space 500, identifying the living organism 400, specifying the movement of the living organism 400, and specifying the posture of the living organism 400. In specifying the position of the living organism 400 in the target space 500, the total distance between the sensing device 100 and the living organism 400 and the distance between the living organism 400 and the third radio device 300 may be calculated, or the direction (angle) of the living organism 400 relative to the sensing device 100 may be specified, or the direction (angle) of the living organism 400 relative to the third radio device 300 may be specified. Note that, as the sensing of the living organism 400, it may be determined whether or not the living organism 400 is present in the target space 500 based on the CSI.

[0054] In addition, when sensing the living body 400, methods such as the MUSIC (MUltiple SIgnal Classification) method, the beamformer method, the Capon method, or other conventionally known methods may be used, and sensors that realize these functions may be provided in the sensing device 100, the second radio device 200, or the third radio device 300.

[0055] FIG. 2 is a diagram illustrating an example of the configuration of the sensing device according to the embodiment.

[0056] The sensing device 100 includes a first radio device 110, an acquisition unit 120, a determination unit 130, a control unit 140, a storage unit 150, and a function unit 160.

[0057] The first radio device 110 includes a transmitting antenna unit 111, a transmitting unit 112, a transmission signal generating unit 113, a receiving antenna unit 114, and a receiving unit 115. The first radio device 110 performs wireless communication using, for example, Wi-Fi in the 2.4 GHz band. That is, the transmitting signal transmitted from the transmitting antenna unit 111 is a wireless signal based on Wi-Fi in the 2.4 GHz band, and the receiving signal received by the receiving antenna unit 114 is a wireless signal based on Wi-Fi in the 2.4 GHz band.

[0058] The transmitting antenna unit 111 has M1 transmitting antenna elements, where M1 is a natural number equal to or greater than 1. The M1 transmitting antenna elements transmit multicarrier signals generated by the transmitting unit 112, which will be described later. The multicarrier signals are an example of transmission waves.

[0059] The transmission signal generating unit 113 generates a multicarrier signal in which a plurality of subcarrier signals are modulated. Specifically, the transmission signal generating unit 113 generates a plurality of subcarrier signals corresponding to a plurality of subcarriers in different frequency bands, and multiplexes the generated subcarrier signals to generate a multicarrier signal. In this embodiment, an example will be described in which the transmission signal generating unit 113 generates an OFDM (Orthogonal Frequency Division Multiplexing) signal consisting of S subcarriers, which has high frequency band utilization efficiency, as the multicarrier signal. Here, S is a natural number equal to or greater than 2. Note that the transmission signal generating unit 113 is not limited to generating an OFDM signal in which the subcarriers are orthogonal, as long as the multicarrier signal is obtained by multicarrier modulation, and may also generate other multicarrier signals, such as a simple FDM (Frequency Division Multiplexing) signal.

[0060] Furthermore, the signal generated by the transmission signal generating unit 113 may be used in common with the signal used for communication. The transmission signal generating unit 113 is not limited to generating a multi-carrier signal, and may also generate a single-carrier signal.

[0061] The transmitter 112 performs appropriate processing on the signal generated by the transmission signal generator 113 to generate a transmission wave. Examples of processing performed here include up-conversion, which converts the signal from an intermediate frequency (IF) frequency band to a radio frequency (RF) frequency band, and amplification, which amplifies the signal to an appropriate transmission level. The transmitter 112 outputs the processed multicarrier signal to the transmitting antenna unit 111, causing the transmitting antenna unit 111 to transmit the multicarrier signal. As a result, the multicarrier signal is transmitted from M1 transmitting antenna elements provided in the transmitting antenna unit 111.

[0062] The receiving antenna unit 114 has N1 receiving antenna elements, where N1 is a natural number equal to or greater than 1. The N1 receiving antenna elements receive signals (received signals) transmitted from the M1 transmitting antenna elements and reflected by the living body 400.

[0063] The receiving unit 115 observes received signals received by N1 receiving antenna elements, including received signals (single-carrier signals or multi-carrier signals) transmitted from M2 transmitting antenna elements of the second radio device 200 and reflected or scattered by the living body 400, for a first period corresponding to a cycle derived from the activity of the living body 400. The cycle derived from the activity of the living body is a cycle derived from the living body (biological fluctuation cycle) that is at least half a cycle of any of the cycles of breathing, heartbeat, and body movement of the living body 400. The received signals may include information about the transmitted signal that is the source of the received signals and was transmitted by the second radio device 200. Note that the information about the transmitted signal that is the source of the received signals does not need to be included in the received signals, and may be transmitted from the second radio device 200 to the sensing device 100 by another means. Here, M2 is a natural number greater than or equal to 1. Furthermore, when one of M2 and N1 is 1, the other is greater than or equal to 2. Note that if it is desired to grasp short-term behavior using an application to be used, the first period may be shorter than the cycle derived from the living body.

[0064] The receiving unit 115 converts high-frequency signals received by the N receiving antenna elements into low-frequency signals that can be processed. When the receiving unit 115 receives an OFDM signal as a multicarrier signal, it demodulates the OFDM signal into S subcarrier signals. The S subcarrier signals are also called S IQ symbols. The S subcarrier signals are low-frequency signals.

[0065] When the receiving unit 115 receives a single-carrier signal, it may measure the RSSI of the single-carrier signal. Furthermore, even when the receiving unit 115 receives a multi-carrier signal, it may measure the RSSI of the multi-carrier signal. That is, the receiving unit 115 sequentially measures the RSSI of a first wireless signal, which is a 2.4 GHz band Wi-Fi signal and is received by the first wireless device 110 located in the target space 500. The first wireless signal is, for example, a beacon signal transmitted from the second wireless device 200. The beacon signal is, for example, a signal periodically transmitted by a master device in Wi-Fi wireless communication, broadcasting the presence of a network by the master device and prompting clients to connect to the network. The beacon signal includes, for example, an SSID (Service Set Identifier). In the 2.4 GHz band Wi-Fi, the beacon signal is a single-carrier signal.

[0066] The receiving unit 115 further calculates a plurality of complex transfer functions representing propagation characteristics H between the transmitting antenna element and the receiving antenna element for each subcarrier from the S subcarrier signals obtained from the plurality of received signals observed over the first period. Note that the receiving unit 115 may constantly observe (or record) the received signals received by the receiving antenna unit 114 and acquire the S subcarrier signals continuously or periodically. In other words, the receiving unit 115 may acquire the S subcarrier signals at a plurality of different timings based on the received signals received at each timing.

[0067] Using the multiple received signals observed over the first period, the receiving unit 115 calculates multiple complex transfer functions, which are propagation characteristics H between the transmitting antenna elements and the receiving antenna elements in each of N1×M2 combinations, which are combinations of each of M2 transmitting antenna elements and each of N1 receiving antenna elements, for each of multiple subcarriers to which the multiple subcarrier signals correspond. Note that the N1×M2 combinations are all possible combinations when M2 transmitting antenna elements and N1 receiving antenna elements are combined one-to-one.

[0068] In this embodiment, S subcarrier signals are used to calculate N1×M2×S sets of complex transfer functions representing the propagation characteristics H between each transmitting antenna element and each receiving antenna element for each of the S subcarrier signals. Note that the calculated complex transfer function matrix also includes reflected waves that do not pass through the living body 400, such as direct waves and reflected waves from fixed objects.

[0069] While the above description has been given of the case where the sensing device 100 receives a transmission signal from the second radio device 200, the same applies when the sensing device 100 receives a transmission signal from the third radio device 300. For example, using a plurality of received signals observed over a first period, the receiver 115 calculates, for each of N1×M3 combinations of M3 transmitting antenna elements and N1 receiving antenna elements of the third radio device 300, a plurality of complex transfer functions representing the propagation characteristics H between the transmitting antenna elements and receiving antenna elements in the combination, for each of a plurality of subcarriers to which a plurality of subcarrier signals correspond. Note that the N1×M3 combinations are all possible combinations when M3 transmitting antenna elements and N1 receiving antenna elements are combined one-to-one. Here, M3 is a natural number greater than or equal to 1. Furthermore, when one of M3 and N1 is 1, the other is greater than or equal to 2.

[0070] FIG. 3 is a diagram for explaining the relationship between a transmission signal, a channel, and a reception signal.

[0071] The transmission signal X transmitted from the transmission antenna unit 211 of the second radio device 200 propagates through the target space 500, is received by the receiving antenna unit 114, and is acquired as a reception signal Y. The reception signal Y received by the receiving antenna unit 114 is a signal that has changed as the transmission signal X propagates through the target space 500. For this reason, the reception signal Y can be considered to be equal to a signal obtained by multiplying the transmission signal X by the propagation characteristic H(CSI) of the target space 500. The propagation characteristic H is expressed by the above-mentioned N1×M2×S set of complex transfer functions.

[0072] FIG. 4 is a diagram for explaining the propagation characteristic H at each timing.

[0073] As described above, the propagation characteristics H have a complex transfer function for each combination of three types of parameters, i.e., for each receiving antenna element, each transmitting antenna element, and each subcarrier. That is, a different complex transfer function is calculated for each of the different multiple receiving antenna elements, a different complex transfer function is calculated for each of the different multiple transmitting antenna elements, and a different complex transfer function is calculated for each of the different multiple subcarriers.

[0074] 5 is a diagram showing an image of propagation characteristic H expressed by a combination of complex transfer functions when the number of receiving antenna elements is 3, the number of transmitting antenna elements is 4, and the number of subcarriers is 2, as shown in FIG. 4. In this case, propagation characteristic H can be expressed as a combination of 3x4x2 blocks. One block represents one complex transfer function calculated for one specific receiving antenna element, one specific transmitting antenna element, and one specific subcarrier. In this way, propagation characteristic H can be expressed three-dimensionally because it is expressed as a combination of three types of parameters: receiving antenna element, transmitting antenna element, and subcarrier. Furthermore, this three-dimensionally expressed propagation characteristic H is calculated for each of multiple timings.

[0075] Note that, with the subcarriers and transmitting antenna elements fixed, multiple complex transfer functions of different receiving antenna elements may be expressed as multiple complex transfer functions that differ in the receiving antenna element direction. Similarly, with the subcarriers and receiving antenna elements fixed, multiple complex transfer functions of different transmitting antenna elements may be expressed as multiple complex transfer functions that differ in the transmitting antenna element direction. Similarly, with the receiving antenna element and transmitting antenna element fixed, multiple complex transfer functions of different subcarriers may be expressed as multiple complex transfer functions that differ in the subcarrier direction. In this way, in the propagation characteristic H expressed three-dimensionally, the directions of each dimension may be expressed as the receiving antenna element direction, the transmitting antenna element direction, and the subcarrier direction using names related to three types of parameters.

[0076] For example, if the rows of a matrix representing propagation characteristic H are assigned to receiving antenna elements in three dimensions and the columns are assigned to transmitting antenna elements, then different propagation characteristics H are calculated for each subcarrier and for each timing of acquiring a received signal. That is, in this embodiment, based on S subcarrier signals transmitted from the receiving unit 115, the propagation characteristics H(s, t) between M transmitting antenna elements and N receiving antenna elements for the s-th subcarrier during observation time t are expressed as a complex transfer function matrix, as shown in Equation 1.

[0077]

number

[0078] The acquiring unit 120 sequentially acquires the RSSIs sequentially measured by the receiving unit 115. The multiple RSSIs sequentially acquired by the acquiring unit 120 may be stored in the storage unit 150. The multiple RSSIs are measurement results of received signals (single-carrier signals or multi-carrier signals) at multiple different timings over a second period.

[0079] Furthermore, the acquiring unit 120 acquires CSI, which is the propagation characteristic H calculated by the receiving unit 115. The acquiring unit 120 acquires a plurality of CSI over a certain period of time. That is, the acquiring unit 120 acquires CSI at each of a plurality of timings over the certain period of time. The plurality of CSIs acquired by the acquiring unit 120 may be stored in the storage unit 150. The plurality of CSIs include a plurality of propagation characteristics H generated based on a plurality of received signals acquired at a plurality of consecutive timings.

[0080] The determination unit 130 determines whether the variation in RSSI exceeds a predetermined threshold based on the multiple RSSIs recorded sequentially. The determination unit 130 may determine that the living organism 400 is present in the target space 500 when the variation in RSSI exceeds a predetermined threshold. The determination unit 130 may determine that the living organism 400 is not present in the target space 500 when the variation in RSSI is equal to or less than a predetermined threshold. Note that the larger the variation in RSSI, the greater the amount of activity of the living organism 400 present in the target space 500. The predetermined threshold indicates that the amount of activity of the living organism 400 is a predetermined amount of activity. In other words, when the variation in RSSI exceeds a predetermined threshold, the determination unit 130 can determine that the amount of activity of the living organism 400 present in the target space 500 is greater than a predetermined amount of activity.

[0081] When the determining unit 130 determines that the RSSI fluctuation has exceeded a predetermined threshold, the control unit 140 causes the first radio device 110 to receive a multicarrier signal (OFDM signal) from the second radio device 200 for a certain period of time. The multicarrier signal is an example of a second radio signal. Specifically, when the determining unit 130 determines that the RSSI fluctuation has exceeded a predetermined threshold, the control unit 140 causes the second radio device 200 to transmit a fourth radio signal to the first radio device 110, thereby causing the first radio device 110 to receive the multicarrier signal for a certain period of time. Here, the fourth radio signal includes ping, Null, and NDP (None Data Packet). The fourth radio signal may include a packet including normal actual data. Since the packet includes a header in which a pilot signal is stored, CSI may be acquired based on the pilot signal.

[0082] When the first radio device 110 transmits the fourth radio signal to the second radio device 200, the second radio device 200 transmits a multicarrier signal to the first radio device 110 as a response signal to the fourth radio signal. This allows the first radio device 110 to receive the multicarrier signal from the second radio device 200. In this way, the control unit 140 causes the first radio device 110 to receive the multicarrier signal for a certain period of time, thereby allowing the acquisition unit 120 to acquire the first CSI based on the multicarrier signal. Therefore, the control unit 140 can perform sensing of the living body 400 in the target space 500 based on the first CSI.

[0083] Furthermore, when a third wireless signal transmitted from the third wireless device 300 for the second wireless device 200 is received (intercepted) by the first wireless device 110, the control unit 140 may perform sensing of the living body 400 in the target space 500 based on the second CSI and the first CSI based on the third wireless signal. Note that the third wireless signal is a wireless signal in a band and channel that the first wireless device 110 can receive.

[0084] Furthermore, when a predetermined condition is satisfied, the control unit 140 may cause the first radio device 110 to receive a multicarrier signal for a certain period of time, thereby performing sensing of the living body 400 in the target space 500 based on the first CSI based on the multicarrier signal. That is, even when a predetermined condition other than when the determination unit 130 determines that the RSSI fluctuation exceeds a predetermined threshold is satisfied, the control unit 140 may cause the first radio device 110 to receive a multicarrier signal for a certain period of time to acquire the first CSI. The predetermined condition may be that a certain period of time has elapsed since the last acquisition of the first CSI, that the first radio device 110 has received a certain signal, or that a certain time has arrived. Here, the control unit 140 is not limited to sensing the living body 400. For example, the control unit 140 may periodically perform sensing using periodically acquired CSI and compare multiple sensing results obtained at different times to determine whether a still object (object) placed in the target space 500 has been moved.

[0085] The control unit 140 may use the plurality of first CSIs to detect the position of the living organism 400 in the target space 500, may specify the posture of the living organism 400, may determine whether the living organism 400 is present in the target space 500, may identify the living organism 400 based on the CSI registered in advance for each individual living organism 400, or may specify the movement of the living organism 400. In specifying the position of the living organism 400 in the target space 500, the control unit 140 may calculate the total distance of the distance between the first radio device 110 and the living organism 400 and the distance between the living organism 400 and the second radio device 200, may specify the direction (angle) of the living organism 400 relative to the first radio device 110, or may specify the direction (angle) of the living organism 400 relative to the second radio device 200.

[0086] Similarly, the control unit 140 may use the plurality of second CSIs to detect the position of the living organism 400 in the target space 500, may specify the posture of the living organism 400, may determine whether the living organism 400 is present in the target space 500, may identify the living organism 400 based on the CSI registered in advance for each individual living organism 400, or may specify the movement of the living organism 400. In specifying the position of the living organism 400 in the target space 500, the control unit 140 may calculate the total distance of the distance between the first radio device 110 and the living organism 400 and the distance between the living organism 400 and the third radio device 300, may specify the direction (angle) of the living organism 400 relative to the first radio device 110, or may specify the direction (angle) of the living organism 400 relative to the third radio device 300.

[0087] The functional unit 160 performs functions specific to the sensing device 100 as a home appliance. The functional unit 160 includes a storage compartment for storing items to be refrigerated, a heat pump for cooling the air, and a blower for sending the air cooled by the heat pump to the storage compartment. The heat pump includes a compressor for compressing a refrigerant, a heat exchanger (an evaporator and a condenser), and an expansion mechanism. If the sensing device 100 is a washing machine, the functional unit 160 includes a washing tub and a motor for rotating the washing tub. If the sensing device 100 is an air conditioner, the functional unit 160 includes a heat pump and a blower for circulating the air cooled or heated by the heat pump inside the room.

[0088] If the sensing device 100 is not a home appliance, the sensing device 100 does not need to include the functional unit 160.

[0089] FIG. 5 is a diagram illustrating an example of the configuration of the second radio device according to the embodiment.

[0090] The second radio device 200 includes a transmitting antenna unit 211, a transmitting unit 212, a transmission signal generating unit 213, a receiving antenna unit 214, and a receiving unit 215. The second radio device 200 performs wireless communication using, for example, Wi-Fi in the 2.4 GHz band. That is, the transmitting signal transmitted from the transmitting antenna unit 211 is a wireless signal based on Wi-Fi in the 2.4 GHz band, and the receiving signal received by the receiving antenna unit 214 is a wireless signal based on Wi-Fi in the 2.4 GHz band. The second radio device 200 differs in configuration from the first radio device 110 in that the transmitting antenna unit 211 has M2 transmitting antenna elements and the receiving antenna unit 214 has N2 receiving antenna elements. However, since the other configurations are the same, a description thereof will be omitted. Here, N2 is a natural number equal to or greater than 1.

[0091] FIG. 6 is a diagram illustrating an example of the configuration of the third radio device according to the embodiment.

[0092] The third radio device 300 includes a transmitting antenna unit 311, a transmitting unit 312, a transmission signal generating unit 313, a receiving antenna unit 314, and a receiving unit 315. The third radio device 300 performs wireless communication using Wi-Fi in the 2.4 GHz band, for example. That is, the transmitting signal transmitted from the transmitting antenna unit 311 is a wireless signal based on Wi-Fi in the 2.4 GHz band, and the receiving signal received by the receiving antenna unit 314 is a wireless signal based on Wi-Fi in the 2.4 GHz band. The third radio device 300 differs in configuration from the first radio device 110 in that the transmitting antenna unit 311 has M3 transmitting antenna elements and the receiving antenna unit 314 has N3 receiving antenna elements. However, the other configurations are the same, and therefore description thereof will be omitted. Here, N3 is a natural number equal to or greater than 1.

[0093] In the sensing system 1, communication may be performed between the second wireless device 200 and the third wireless device 300. Even in this case, communication is performed in the same manner as communication between the sensing device 100 and the second wireless device 200.

[0094] [Operation] Next, the operation of the sensing device 100 according to the embodiment will be described.

[0095] FIG. 7 is a flowchart illustrating an example of a sensing method performed by the sensing device according to the embodiment.

[0096] The sensing device 100 sequentially receives a beacon signal as a first wireless signal from the second wireless device 200 (S11).

[0097] The sensing device 100 sequentially acquires the RSSI of the beacon signal (S12).

[0098] The sensing device 100 records the multiple RSSIs that are sequentially acquired (S13), whereby the storage unit 150 stores the multiple RSSIs.

[0099] The sensing device 100 may measure (acquire) the RSSI of the received beacon signal and record the RSSI in the storage unit 150 every time the sensing device 100 receives a beacon signal.

[0100] The sensing device 100 determines whether the fluctuation of the RSSI exceeds a predetermined threshold based on the plurality of RSSIs (S14). The plurality of RSSIs are measurement results of the beacon signal at a plurality of different timings over the second period. That is, the sensing device 100 determines whether the fluctuation of the RSSI during the second period exceeds a predetermined threshold.

[0101] If the fluctuation in the RSSI exceeds a predetermined threshold (Yes in S14), the sensing device 100 transmits a fourth wireless signal to the second wireless device 200 (S15).

[0102] As a result, the sensing device 100 receives the multi-carrier signal as the second wireless signal from the second wireless device 200 (S16).

[0103] The sensing device 100 senses the living body 400 in the target space 500 based on the first CSI obtained by receiving the multicarrier signal (S17).

[0104] If the fluctuation in RSSI is equal to or less than the predetermined threshold (No in S14), the sensing device 100 skips steps S15 to S17 and ends the process.

[0105] The sensing device 100 may perform sensing of the living body 400 based on the second CSI obtained by intercepting the third wireless signal intended for the second wireless device 200 by the third wireless device 300.

[0106] 8 is a flowchart showing another example of a sensing method performed by the sensing device according to the embodiment. The sensing method in FIG. 8 will be described as being performed in parallel with the sensing method in FIG.

[0107] The sensing device 100 receives a third wireless signal transmitted from the third wireless device 300 for the second wireless device 200 (S21). The third wireless signal is a multi-carrier signal.

[0108] The sensing device 100 determines whether or not the second wireless signal has been received from the second wireless device 200 (S22). For example, the sensing device 100 determines whether or not the second wireless signal has been received from the second wireless device 200 after a timing that is a third period before the timing at which the third wireless signal was received. In other words, the sensing device 100 determines whether or not the second wireless signal and the third wireless signal have been received during the third period. The third period is, for example, 1 to 5 minutes.

[0109] When the sensing device 100 determines that the second wireless signal has been received from the second wireless device 200 (Yes in S22), the sensing device 100 senses the living body 400 based on the second wireless signal and the third wireless signal (S23). That is, the sensing device 100 senses the living body 400 in the target space 500 based on the first CSI and the second CSI.

[0110] When the sensing device 100 determines that the second wireless signal has not been received from the second wireless device 200 (No in S22), the sensing device 100 senses the living body 400 based on the third wireless signal (S24). That is, the sensing device 100 senses the living body 400 in the target space 500 based on the second CSI.

[0111] [Effects, etc.] The sensing device 100 according to this embodiment includes an acquisition unit 120 and a control unit 140. The acquisition unit 120 sequentially acquires the RSSI of a first wireless signal, which is a first wireless signal via Wi-Fi in the 2.4 GHz band, received by a first wireless device 110 placed in a target space 500. When fluctuations in the RSSI exceed a predetermined threshold, the control unit 140 causes the first wireless device 110 to receive a second wireless signal transmitted from a second wireless device 200 for a certain period of time, thereby performing sensing of a living body 400 in the target space 500 based on the first CSI based on the second wireless signal.

[0112] According to this, when the variation in RSSI exceeds a predetermined threshold, sensing of the living organism 400 is performed using the second wireless signal transmitted from the second wireless device 200. Therefore, when there is a high possibility that the living organism 400 exists in the target space 500, for example, sensing of the living organism 400 can be performed using the second wireless signal, which consumes more energy when receiving than the first wireless signal and can obtain highly accurate sensing results. Therefore, when there is a low possibility that the living organism 400 exists in the target space 500, it is possible to reduce the number of times that sensing of the living organism is performed using the second wireless signal, which requires more energy consumption, and it is possible to sense the living organism 400 with less energy consumption. Therefore, for example, it is possible to reduce power consumption of a battery for wireless communication.

[0113] In addition, the sensing device 100 according to this embodiment further includes a determination unit 130 that determines that a living body 400 is present in the target space 500 when the fluctuation in the RSSI of the first wireless signal received by the first wireless device 110 exceeds a predetermined threshold.

[0114] Therefore, when it is determined that the living body 400 is not present in the target space 500, sensing of the living body 400 using the second wireless signal, which requires more energy consumption, can be suppressed, and sensing of the living body 400 can be performed with less energy consumption.

[0115] Furthermore, in the sensing device 100 according to this embodiment, when a third wireless signal transmitted from the third wireless device 300 for the second wireless device 200 is received by the first wireless device 110, the control unit 140 senses the living body 400 in the target space 500 based on the second CSI and the first CSI based on the third wireless signal.

[0116] Therefore, sensing of the living body 400 in the target space 500 is performed based on the second CSI based on the third wireless signal from the third wireless device 300, and sensing of the living body 400 in the target space 500 is performed based on the first CSI based on the second wireless signal from the second wireless device 200, so that sensing of the living body 400 can be performed more accurately.

[0117] In the sensing device 100 according to this embodiment, the first wireless signal is a beacon signal, and the second wireless signal is a multi-carrier signal.

[0118] According to this, when it is determined that there is a high possibility that the living organism 400 is present in the target space 500 using a beacon signal that can be received with less energy consumption, it is possible to sense the living organism 400 using a multicarrier signal that consumes more energy than a beacon signal when receiving and that can obtain highly accurate sensing results. Therefore, when there is a low possibility that the living organism 400 is present in the target space 500, it is possible to reduce sensing of the living organism 400 using the second wireless signal that requires more energy consumption, and it is possible to sense the living organism 400 with less energy consumption.

[0119] Furthermore, in the sensing device 100 according to this embodiment, a larger variation in RSSI indicates a larger amount of activity of the living organism 400 present in the target space 500. Furthermore, the predetermined threshold indicates that the amount of activity of the living organism 400 is a predetermined amount of activity.

[0120] According to this, when the variation in RSSI exceeds a predetermined threshold and the activity amount of the living organism 400 present in the target space 500 is greater than a predetermined activity amount, sensing of the living organism 400 is performed using the second wireless signal transmitted from the second wireless device 200. When the activity amount of the living organism 400 present in the target space 500 is greater than a predetermined activity amount, there is a high possibility that the living organism 400 is present in the target space 500. Therefore, when there is a high possibility that the living organism 400 is present in the target space 500, it is possible to sense the living organism 400 using, for example, the second wireless signal, which consumes more energy when receiving than the first wireless signal and can obtain highly accurate sensing results. Therefore, when there is a low possibility that the living organism 400 is present in the target space 500, it is possible to reduce sensing of the living organism 400 using the second wireless signal, which requires more energy consumption, and it is possible to sense the living organism 400 with less energy consumption.

[0121] Furthermore, in the sensing device 100 according to this embodiment, when a predetermined condition is further satisfied, the control unit 140 causes the first radio unit 110 to receive the second radio signal for a certain period of time, thereby sensing the living body 400 in the target space 500 based on the first CSI based on the second radio signal.

[0122] Therefore, the condition for sensing the living body 400 using the second wireless signal transmitted from the second wireless device 200 can be limited to when the fluctuation in RSSI exceeds a predetermined threshold or when a predetermined condition is satisfied.

[0123] Furthermore, in the sensing device 100 according to this embodiment, when the fluctuation in RSSI exceeds a predetermined threshold, the control unit 140 causes the second radio device 200 to transmit a fourth radio signal to the first radio device 110, thereby causing the first radio device 110 to receive the second radio signal for a certain period of time.

[0124] Therefore, by causing the first radio device 110 to transmit the fourth radio signal, it is possible to receive, for example, the second radio signal transmitted from the second radio device 200 as a response to the fourth radio signal.

[0125] (Variation 1) The sensing device 100 according to the first modification may execute the process shown in FIG.

[0126] FIG. 9 is a flowchart showing an example of a sensing method by the sensing device according to the first modification.

[0127] The sensing device 100 sequentially receives a beacon signal as a first wireless signal from the second wireless device 200 (S31).

[0128] The sensing device 100 sequentially acquires the RSSI of the beacon signal (S32).

[0129] The sensing device 100 records the multiple RSSIs that are sequentially acquired (S33), whereby the storage unit 150 stores the multiple RSSIs.

[0130] The sensing device 100 may measure (acquire) the RSSI of the received beacon signal and record the RSSI in the storage unit 150 every time the sensing device 100 receives a beacon signal.

[0131] The sensing device 100 determines whether the fluctuation of the RSSI exceeds a predetermined threshold based on the plurality of RSSIs (S34). The plurality of RSSIs are measurement results of the beacon signal at a plurality of different timings over the second period. That is, the sensing device 100 determines whether the fluctuation of the RSSI during the second period exceeds a predetermined threshold.

[0132] If the variation in RSSI exceeds a predetermined threshold (Yes in S34), the sensing device 100 determines that a living body 400 is present in the target space 500 (S35).

[0133] If the variation in RSSI is equal to or less than the predetermined threshold (No in S34), the sensing device 100 determines that the living body 400 is not present in the target space 500 (S36).

[0134] The sensing device 100 according to the first modification includes an acquisition unit 120 and a determination unit 130. The acquisition unit 120 sequentially acquires the RSSI of a first wireless signal, which is a Wi-Fi first wireless signal, received by a first wireless device 110 placed in the target space 500. The determination unit 130 determines whether or not a living body is present in the target space 500 based on fluctuations in the RSSI.

[0135] For example, by using the fluctuation in the RSSI of a beacon signal when the first wireless device 110 receives a beacon signal that consumes less energy, it may be possible to sense the living body 400 with less energy consumption.

[0136] The first wireless signal is not limited to a single-carrier signal such as a beacon signal, but may be a multi-carrier signal. Since the RSSI can be measured even for a multi-carrier signal, the sensing method of the first modification can be applied.

[0137] (Variation 2) The sensing device 100 according to the second modification may execute the process shown in FIG.

[0138] FIG. 10 is a flowchart showing an example of a sensing method by the sensing device according to the second modification.

[0139] The sensing device 100 receives a third wireless signal transmitted from the third wireless device 300 for the second wireless device 200 (S41). The third wireless signal is a multi-carrier signal.

[0140] The sensing device 100 senses the living body 400 based on the third wireless signal (S42). That is, the sensing device 100 senses the living body 400 in the target space 500 based on the second CSI.

[0141] The sensing device 100 according to the second modification includes a control unit 140. The control unit 140 causes the first radio device 110 placed in the target space 500 to receive, for a certain period of time, a first radio signal via Wi-Fi that is transmitted from the third radio device 300 for the second radio device 200, thereby sensing the living body 400 in the target space 500 based on the CSI based on the radio signal.

[0142] Therefore, by receiving the wireless signal transmitted from the third wireless device 300 for the second wireless device 200 without causing the first wireless device 110 to perform a transmission operation, it is possible to sense the living body 400 in the target space 500. Therefore, it is possible to sense the living body 400 with less energy consumption.

[0143] In the second modification, the sensing device 100 (first radio device 110), the second radio device 200, and the third radio device 300 may be capable of wireless communication not only by Wi-Fi in the 2.4 GHz band, but also by Wi-Fi in the 5 GHz band. Unlike Wi-Fi in the 2.4 GHz band, beacon signals in Wi-Fi in the 5 GHz band are also multi-carrier signals, and therefore can be applied to the sensing method of the second modification.

[0144] (Variation 3) In the above embodiment, the sensing device 100 may be configured separately from the first radio device 110. In this case, the sensing device 100 may acquire the CSI calculated based on the signal received by the first radio device 110 by communicating with the first radio device 110.

[0145] (Variation 4) In the above embodiment, the CSI is calculated based on the received signal (multicarrier signal) obtained by receiving unit 115. However, the CSI may be calculated based on the radio signal obtained after the received signal received by receiving unit 115 is amplified by an amplifier. Alternatively, the CSI may be calculated by dividing the amplified radio signal by the gain achieved by the amplifier to calculate the pre-amplified radio signal, and the CSI may be calculated based on the calculated pre-amplified radio signal. The gain achieved by the amplifier is adaptively determined for the received signal by AGC (Auto Gain Control). Therefore, the pre-amplified radio signal is calculated by identifying the gain used to calculate the amplified radio signal and dividing the amplified radio signal by the identified gain.

[0146] (Variation 5) In the above embodiment, the acquiring unit 120 acquires the RSSI and CSI from the receiving unit 115, but this is not limiting. The acquiring unit 120 may acquire the RSSI by acquiring a beacon signal from the receiving unit 115 and measuring the RSSI of the acquired beacon signal. Alternatively, the acquiring unit 120 may acquire the CSI by acquiring a multicarrier signal from the receiving unit 115 and calculating the CSI based on the acquired multicarrier signal.

[0147] (others) The current consumption when waiting for a beacon signal is 10 mA or less, and the current consumption when transmitting a fourth wireless signal including Ping, Null, NDP, etc. for receiving a multicarrier signal is several tens of mA. In other words, the power consumption for receiving a multicarrier signal is several times that when waiting for a beacon signal.

[0148] In each of the above embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may also be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0149] Furthermore, the present disclosure can be realized not only as a sensing device having such characteristic components, but also as a sensing method in which the characteristic components included in the sensing device are used as steps. It can also be realized as a computer program that causes a computer to execute each of the characteristic steps included in such a method. It goes without saying that such a computer program can be distributed on a computer-readable non-transitory recording medium such as a CD-ROM or via a communication network such as the Internet. [Industrial Applicability]

[0150] The present disclosure can be used in sensing devices and sensing methods that estimate the distance and position of a living body using wireless signals, and in particular in measuring devices that measure the distance and position of a living body, including between a living body and a machine, home appliances that perform control according to the distance and position of a living body, and monitoring devices that detect the intrusion of a living body. [Explanation of symbols]

[0151] 1. Sensing System 100 Sensing Device 110 First Radio 111, 211, 311 Transmitting antenna section 112, 212, 312 Transmitter 113, 213, 313 Transmission signal generation unit 114, 214, 314 Receiving antenna section 115, 215, 315 Receiver 120 Acquisition Department 130 Judgment section 140 Control Unit 150 Storage section 200 Second Radio 300 Third Radio 400 living organisms 500 Target Space

Claims

1. an acquisition unit that sequentially acquires a received signal strength indicator (RSSI) of a first wireless signal received by a first wireless device disposed in a target space, the first wireless signal being a Wi-Fi signal; a determination unit that determines whether or not a living body is present in the target space based on the variation in the RSSI. Sensing device.

2. an acquisition unit configured to sequentially acquire an RSSI of a first wireless signal received by a first wireless device disposed in a target space, the first wireless signal being a 2.4 GHz band Wi-Fi signal; a control unit that, when a fluctuation in the RSSI exceeds a predetermined threshold, causes the first radio device to receive a second radio signal from a second radio device for a certain period of time, thereby performing sensing of a living body in the target space based on first CSI (Channel State Information) based on the second radio signal. Sensing device.

3. moreover, a determination unit that determines that a living body is present in the target space when a fluctuation in RSSI of the first wireless signal received by the first wireless device exceeds a predetermined threshold value; The sensing device according to claim 2 .

4. the first wireless device is a slave device in Wi-Fi wireless communication, The second wireless device is a master device in the Wi-Fi wireless communication. The sensing device according to claim 2 or 3.

5. The control unit further When a third wireless signal transmitted from a third wireless device for the second wireless device is received by the first wireless device, sensing of a living body in the target space is performed based on a second CSI based on the third wireless signal and the first CSI. The sensing device according to claim 2 or 3.

6. the first wireless signal is a beacon signal; The second radio signal is a multi-carrier signal. The sensing device according to claim 2 or 3.

7. The larger the fluctuation of the RSSI, the greater the amount of activity of the living organism present in the target space, and The predetermined threshold indicates that the activity amount of the living body is a predetermined activity amount. The sensing device according to claim 2 or 3.

8. The control unit, when a predetermined condition is further satisfied, causes the first radio device to receive the second radio signal for a certain period of time, thereby performing sensing of a living body in the target space based on first CSI based on the second radio signal. The sensing device according to claim 2 or 3.

9. When the fluctuation exceeds the predetermined threshold, the control unit causes the second radio device to transmit a fourth radio signal to the first radio device, thereby causing the first radio device to receive the second radio signal for a certain period of time. The sensing device according to claim 2 or 3.

10. The fourth wireless signal includes a ping, a null, and an NDP (None Data Packet). The sensing device according to claim 9 .

11. The control unit is configured to cause a first wireless device disposed in a target space to receive a first wireless signal via Wi-Fi, the wireless signal being transmitted from a third wireless device for a second wireless device, for a certain period of time, thereby sensing a living body in the target space based on CSI based on the wireless signal. Sensing device.

12. Sequentially acquiring RSSI (Received Signal Strength Indicator) of a first wireless signal received by a first wireless device disposed in a target space, the first wireless signal being a Wi-Fi signal; Based on the fluctuation of the RSSI, it is determined whether or not a living body is present in the target space. Sensing method.

13. Sequentially acquiring RSSIs of first wireless signals received by a first wireless device disposed in the target space, the first wireless signals being Wi-Fi signals in the 2.4 GHz band; When the fluctuation of the RSSI exceeds a predetermined threshold, the first radio device receives a second radio signal from a second radio device for a certain period of time, thereby acquiring first CSI (Channel State Information) based on the second radio signal; Sensing a living body in the target space based on the first CSI. Sensing method.

14. a first wireless signal transmitted by a third wireless device for a second wireless device via Wi-Fi is received by a first wireless device located in a target space for a certain period of time, thereby acquiring CSI based on the wireless signal; Sensing a living body in the target space based on the CSI Sensing method.

15. A program for causing a computer to execute the sensing method according to claim 12.

Images