Wireless communication method, wireless communication device, and wireless communication system

Abstract

To enable a communication of a wireless LAN and a back scatter (BS) communication to be present together while avoiding collision of a signal of the wireless LAN and a BS signal regarding a wireless communication method appropriate for utilizing the BS communication.SOLUTION: A wireless device 10 comprising a function as an access point of a wireless LAN transmits a signal 12 for BS including a preamble signal 50 specified in the wireless LAN and a BS signal 52. A BS device 16 acquires drive power from the signal 12 for BS and transmits a modulation signal 14. The wireless device 10, which receives the modulation signal 14, processes the modulation signal 14 and sets up a BS communication. A wireless terminal 18 comprising a function for limiting data transmission according to a CSMA / CA approach limits the data transmission in reaction to the preamble signal 50.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a wireless communication method, a wireless communication device, and a wireless communication system, and more particularly to a wireless communication method, a wireless communication device, and a wireless communication system suitable for use in backscatter communication. [Background technology]

[0002] Non-Patent Document 1 below discloses a technology that combines backscatter (hereinafter referred to as "BS") communication technology with wireless LAN (Local Area Network) technology. BS communication is a technology that applies radar technology to enable data communication between objects without using a power source.

[0003] BS communication uses a wireless device that issues a query and a BS tag that receives the query. The BS tag obtains driving power from the wireless signal (hereinafter referred to as "BS signal") emitted from the wireless device and switches between an ON state in which it reflects the BS signal and an OFF state in which it does not reflect the BS signal. The ON and OFF states are switched so that the reflected wave becomes the answer to the query. Hereinafter, this reflected wave will be referred to as a "modulated signal."

[0004] For example, the identifier of the BS tag can be embedded in the modulated signal. Alternatively, a sensor can be mounted on the BS tag and the detected value of the sensor can be embedded in the modulated signal. A wireless device that issues a query can receive the modulated signal from the BS tag and obtain a response to the query.

[0005] Non-Patent Document 1 below discloses a technology that allows a wireless terminal capable of Wi-Fi (registered trademark) communication to receive a modulated signal emitted by a BS tag. This technology makes it possible to connect BS communication to the Internet. BS tags can be operated without power supply, so they can be easily installed in various locations. Therefore, the combination of BS communication and wireless LAN can greatly expand the possibilities of IoT (Internet of Things), which consumes little power. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "Wi-Fi backscatter: Internet connectivity for RF-powered devices", Bryce Kellogg, Aaron Parks, Shyamnath Gollakota, Joshua R. Smith, and David Wetherall, University of Washington, Proceedings of the 2014 ACM Conference on SIGCOMM. 2014, Page 607-618.https: / / dl.acm.org / doi / abs / 10.1145 / 2619239.2626319 Summary of the Invention [Problem to be solved by the invention]

[0007] In the field of wireless LANs, the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) method is sometimes used to avoid signal collisions caused by multiple wireless devices transmitting data simultaneously. In CSMA / CA, each wireless device continuously monitors the shared wireless channel and transmits a signal only after confirming that the channel has been free for a certain period of time.

[0008] On the other hand, conventional BS signals used in BS communications do not comply with wireless LAN regulations. Therefore, in an environment where BS communications and wireless LAN communications overlap, the BS signals may not be recognized by wireless LAN devices. In this case, even though the BS signals are being transmitted, the wireless LAN devices may mistakenly believe that the channel is free and transmit data, resulting in a collision between the wireless LAN signals and the BS signals.

[0009] The present disclosure has been made in light of the above-mentioned problems, and its primary objective is to provide a wireless communication method that allows wireless LAN communication and BS communication to coexist while avoiding collisions between wireless LAN signals and BS signals. A second object of the present disclosure is to provide a wireless communication device that allows wireless LAN communication and BS communication to coexist while avoiding collision between the wireless LAN signal and the BS signal. Furthermore, a third object of the present disclosure is to provide a wireless communication system that allows wireless LAN communication and BS communication to coexist while avoiding collision between the wireless LAN signal and the BS signal. [Means for solving the problem]

[0010] In order to achieve the above object, a first aspect of the present disclosure is a wireless communication method, comprising: A step in which a wireless device having a function as an access point of a wireless LAN transmits a BS signal including a preamble signal and a BS signal specified in the wireless LAN; a BS device transmitting a modulated signal generated by obtaining driving power from the BS signal; a step of processing the modulated signal by a wireless device receiving the modulated signal; a step in which a wireless terminal having a function of restricting data transmission by a CSMA / CA method restricts data transmission in response to the preamble signal; It is desirable to include:

[0011] A second aspect of the present disclosure is a wireless device having a function as an access point of a wireless LAN, a wireless communication unit that transmits and receives wireless signals used in wireless LAN communication, and BS signals and modulated signals used in BS communication; a control unit that controls the wireless communication unit, It is desirable that the control unit be configured to cause the wireless communication unit to transmit a BS signal including a preamble signal defined by a wireless LAN and a BS signal for BS communication.

[0012] A third aspect of the present disclosure is a wireless communication system, a wireless device configured to function as an access point of a wireless LAN and to have a function of transmitting a BS signal; a BS device that acquires driving power from the BS signal and transmits a generated modulated signal; a radio device that receives and processes the modulated signal; A wireless terminal having a function of restricting data transmission using a CSMA / CA method, The wireless device is preferably configured to include in the BS signal a preamble signal specified in a wireless LAN in addition to a BS signal for BS communication. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to allow wireless LAN communication and BS communication to coexist while avoiding collision between wireless LAN signals and BS signals. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of the present disclosure. [Figure 2] 2 is a block diagram illustrating the configuration of a wireless device included in the wireless communication system shown in FIG. [Figure 3] 2 is a block diagram for explaining the configuration of a BS device included in the wireless communication system shown in FIG. [Figure 4] 2 is a block diagram illustrating the configuration of a wireless terminal included in the wireless communication system shown in FIG. [Figure 5] 1 is a diagram illustrating the configuration and features of a wireless communication system according to a first embodiment of the present disclosure. [Figure 6] 4 is a flowchart illustrating a flow of processing executed in the wireless communication system according to the first embodiment of the present disclosure. [Figure 7] FIG. 10 is a diagram illustrating a configuration of a modified example of the wireless communication system according to the first embodiment of the present disclosure. [Figure 8] FIG. 10 is a diagram illustrating the configuration and features of a wireless communication system according to a second embodiment of the present disclosure. [Figure 9] 10 is a flowchart illustrating a flow of processing executed by a BS device in a second embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram illustrating the configuration and features of a wireless communication system according to a third embodiment of the present disclosure. [Figure 11] 13 is a flowchart illustrating a flow of processing executed by a wireless device according to a fourth embodiment of the present disclosure. [Figure 12] FIG. 10 is a diagram illustrating the configuration and features of a wireless communication system according to a fifth embodiment of the present disclosure. [Figure 13] 13 is a flowchart illustrating a flow of processing executed by a wireless device according to a fifth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] Embodiment 1 [Configuration of the First Embodiment] Fig. 1 is a diagram illustrating the configuration of a wireless communication system according to a first embodiment of the present disclosure. As shown in Fig. 1, the wireless communication system according to this embodiment includes a wireless device 10. The wireless device 10 functions as an access point (AP) of a wireless LAN, and is connected to a higher-level communication device via a wired path (not shown). The AP functions include transmitting a wireless signal when a channel is confirmed to be available for a certain period of time or more using the CSMA / CA technique.

[0016] The wireless device 10 also has a function of processing signals for BS communication using wireless LAN frequencies. More specifically, it has a function of transmitting BS signals 12 for BS communication and a function of receiving modulated signals 14 for BS communication. The BS signals 12 reach the BS device 16 and also reach wireless terminals 18 present in the vicinity of the wireless device 10.

[0017] The BS device 16 may have the shape of a tag that can be attached to various devices incorporated in an IoT system. The BS device 16 obtains driving power from the BS signal 12 and switches between an ON state in which the signal is reflected and an OFF state in which the signal is not reflected. The BS device 16 switches between the ON state and the OFF state to appropriately reflect the BS signal 12, thereby generating a modulated signal 14 in which information to be transmitted via BS communication is embedded.

[0018] Wireless terminal 18 has the function of communicating with wireless device 10 using a wireless LAN function. For example, a smartphone or a tablet terminal corresponds to wireless terminal 18. Like the AP, wireless terminal 18 has the function of starting data transmission when it is able to confirm that a channel is available using the CSMA / CA method.

[0019] 2 is a block diagram illustrating an example of the configuration of wireless device 10. Wireless device 10 includes a control unit 20. Control unit 20 includes an arithmetic processing unit and a memory. The functions of control unit 20 are realized by the arithmetic processing unit executing processes in accordance with programs stored in the memory.

[0020] The wireless device 10 includes a wireless communication unit 22. The wireless communication unit 22 has the function of transmitting and receiving wireless signals in accordance with the rules of wireless LAN. This function includes the above-mentioned CSMA / CA function. The wireless communication unit 22 also has the function of transmitting the above-mentioned BS signal 12 and the function of receiving the above-mentioned modulated signal 14.

[0021] The wireless device 10 also includes a wired communication unit 26. The wired communication unit 26 has a function of connecting the wireless device 10 to a higher-level communication device. The wireless device 10 is connected to an external network such as the Internet via the wired communication unit 26.

[0022] In the wireless device 10, the wireless communication unit 22 performs appropriate processing in response to a command from the control unit 20, thereby establishing communication with the BS device 16 and communication with the wireless terminal 18. In the wireless device 10, the wired communication unit 26 performs appropriate processing in response to a command from the control unit 20, thereby establishing information communication between the BS device 16 and the wireless terminal 18 and the upper network.

[0023] Fig. 3 is a block diagram illustrating an example of the configuration of the BS device 16. As shown in Fig. 3, the BS device 16 includes a control unit 30. A sensor 32 and an RF switch 34 are connected to the control unit 30. An antenna 36 for receiving the BS signal 12 is also connected to the RF switch 34.

[0024] The control unit 30 includes a power supply circuit that obtains drive power from the BS signal received by the antenna 36. The BS device 16 operates on the power obtained by the power supply circuit. Therefore, the BS device 16 can operate continuously without being equipped with a battery or requiring an external power supply.

[0025] When the antenna 36 receives the BS signal 12, the control unit 30 drives the RF switch 34 in accordance with a prescribed rule. The RF switch 34 switches between an ON state, in which the BS signal 12 is reflected, and an OFF state, in which the BS signal 12 is not reflected, in response to a command from the control unit 30. As a result, the BS signal 12 is modulated into a binarized modulated signal 14. The modulated signal 14 is then emitted from the antenna 36 as a reflected wave.

[0026] An identifier may be assigned to control unit 30. In this case, control unit 30 may drive RF switch 34 so that the identifier is embedded in modulated signal 14. Control unit 30 may also obtain a detection value from sensor 32 and drive the RF switch so that the detection value is embedded in modulated signal 14. These operations enable the identifier assigned to BS device 16 and the detection value of sensor 32 to be embedded in modulated signal 14.

[0027] Fig. 4 is a block diagram illustrating an example of the configuration of wireless terminal 18. As shown in Fig. 4, wireless terminal 18 includes a control unit 40. Control unit 40 includes an arithmetic processing unit and a memory. The functions of control unit 40 are realized by the arithmetic processing unit executing processing in accordance with a program stored in the memory.

[0028] The wireless terminal 18 includes a wireless communication unit 42. The wireless communication unit 42 has the function of transmitting and receiving wireless signals in accordance with the rules of the wireless LAN. This function includes the above-mentioned CSMA / CA function.

[0029] [Features of the first embodiment] Fig. 5 is a diagram illustrating features of the wireless communication system of this embodiment. More specifically, Fig. 5 shows how a BS signal 12 emitted from a wireless device 10 includes a preamble signal 50 and a BS signal 52. That is, in this embodiment, the wireless device 10 transmits a BS signal 12 that is obtained by adding a preamble signal 50 specified in wireless LAN to a BS signal 52 that is configured using a signal such as a radar. The BS signal 52 can be configured, for example, as a CW (Continuous Wave) signal, a chirp signal whose frequency increases or decreases over time, or an FMCW signal whose frequency increases linearly over time.

[0030] The wireless device 10 has a function of checking for available channels using the CSMA / CA technique. Therefore, the wireless device 10 can transmit the BS signal 12 at a time when the wireless terminal 18 is not transmitting a wireless signal. Furthermore, since the BS signal 12 includes a preamble signal 50, the wireless terminal 18 can recognize the presence of the BS signal 12 using the CSMA / CA technique when the BS signal 12 is being transmitted. Therefore, the wireless terminal 18 will not transmit a wireless signal at a timing that will collide with the BS signal 12. Therefore, the wireless communication system of this embodiment allows wireless LAN communication and BS communication to coexist while avoiding signal collisions.

[0031] [Processing flow in the first embodiment] Fig. 6 is a flowchart illustrating the flow of processing executed in this embodiment to realize the above-mentioned functions. In the example shown in Fig. 6, first, a BS signal 12 is transmitted from a wireless device 10 (step 100). As described above, the BS signal 12 is transmitted in accordance with the CSMA / CA method at a timing that does not collide with a wireless LAN signal.

[0032] The BS signal 12 transmitted in step 100 above reaches the BS device 16. The BS device 16 receives the BS signal 52 included in the BS signal 12 (step 200), and generates a modulated signal 14 with its own identifier and the like embedded therein (step 202).

[0033] The modulated signal 14 generated in the BS device 16 is received by the wireless device 10 (step 102). This allows BS communication between the wireless device 10 and the BS device 16. The wireless device 10 can provide information obtained from the BS device 16 to other devices via the Internet or the like.

[0034] The BS signal 12 sent in step 100 also reaches the wireless terminal 18. The wireless terminal 18 receives the preamble signal 50 included in the BS signal 12 (step 300) and recognizes, by the function of CSMA / CA, that another device is transmitting a wireless signal.

[0035] In this case, the wireless terminal 18 executes a transmission restriction process (step 302) to prohibit the transmission of a wireless signal. This makes it possible to prevent the wireless terminal 18 from transmitting a wireless signal at a timing that would cause a collision with the BS signal 12. Therefore, according to the wireless communication system of this embodiment, wireless LAN communication and BS communication can coexist without causing a signal collision.

[0036] [Modification of the first embodiment] Fig. 7 is a diagram illustrating the configuration of a modified example of the wireless communication system of this embodiment. The wireless communication system shown in Fig. 7 includes wireless device 10-2 in addition to the configuration shown in Fig. 1. Wireless device 10-2 has the function of receiving and processing modulated signal 14 generated by BS device 16.

[0037] That is, in the above-described first embodiment, wireless device 10 having the function of serving as an AP has both the function of transmitting BS signal 12 and the function of receiving and processing modulated signal 14. However, depending on the installation location of BS device 16, it may be desirable to receive modulated signal 14 at a location different from the installation location of wireless device 10. In such a case, the function of transmitting BS signal 12 and the function of receiving modulated signal 14 may be assigned to separate wireless devices 10, 10-2 as shown in FIG.

[0038] In this case, wireless device 10 may or may not have a function to receive modulated signal 14. Wireless device 10-2 may be connected to a higher-level network via a wired path, similar to wireless device 10. Alternatively, wireless device 10-2 may relay modulated signal 14 and provide it to wireless device 10.

[0039] Furthermore, in the above-described first embodiment, the wireless communication system is exemplified as including one BS device 16 and one wireless terminal 18, but the number of BS devices 16 and wireless terminals 18 is not limited to one. Similarly, in the modification shown in Fig. 7, the number of wireless devices 10-2 receiving modulated signal 14 is not limited to one. There may be a plurality of BS devices 16, wireless terminals 18, and wireless devices 10-2.

[0040] The above modifications can also be applied to wireless communication systems of other embodiments described below.

[0041] Embodiment 2 [Configuration and Features of the Second Embodiment] Next, a second embodiment of the present disclosure will be described with reference to Figures 8 and 9. Figure 8 is a diagram illustrating the configuration and features of a wireless communication system according to the second embodiment of the present disclosure. The system shown in Figure 8 is similar to the system according to the first embodiment, except that wireless device 10 is replaced with wireless device 10-3 and BS device 16 is replaced with BS device 16-2. In Figure 8, elements that are the same as those shown in Figure 1 are denoted by the same reference numerals, and their description will be omitted or simplified.

[0042] 8 shows, more specifically, the wireless device 10-3 transmitting the BS signal 12-2 including the identification signal 54. That is, in this embodiment, the wireless device 10-3 transmits the BS signal 12-2 including the preamble signal 50, the identification signal 54, and the BS signal 52, in that order.

[0043] The wireless communication system of this embodiment may include multiple BS devices 16-2, as in the first embodiment. In such an environment, wireless device 10-3 may want to issue a query to only one or some of the multiple BS devices 16-2. Identification signal 54 is a signal for specifying the destination of the query.

[0044] When the BS device 16-2 receives the BS signal 12-2, it determines whether the signal is addressed to it based on the identification signal 54. If the BS signal 12-2 is addressed to it, it generates the modulated signal 14 in response to the signal. On the other hand, if the BS signal 12-2 is not addressed to it, it ignores the signal.

[0045] [Processing flow in the second embodiment] 9 is a flowchart for explaining the flow of processing performed by the BS device 16-2 in this embodiment to realize the above-mentioned functions. In FIG. 9, steps in which the processing is common to the steps shown in FIG. 6 are assigned the same reference numerals, and their explanations are omitted or simplified.

[0046] 9, when the BS device 16-2 of this embodiment receives the BS signal 12-2 in step 200, it determines whether the signal is addressed to itself (step 210). This determination is made based on whether the identification signal 54 included in the BS signal 12-2 corresponds to its own identifier.

[0047] As a result, if it is recognized that the received BS signal 12-2 is addressed to itself, the modulated signal 14 is generated by the process of step 202. On the other hand, if it is determined that the signal is not addressed to itself, the process of step 202 is skipped.

[0048] As described above, in this embodiment, by adding the identification signal 54 to the BS signal 12-2, it becomes possible to control the modulation operation of BS communication. This also makes it possible to skip signal processing in the BS device 16-2 that is not designated as the destination. Therefore, according to this embodiment, it is possible to achieve power saving throughout the entire wireless communication system.

[0049] Also in this embodiment, the signal for BS 12-2 includes the preamble signal 50 defined by the wireless LAN, as in the case of embodiment 1. Therefore, in this embodiment, as in the case of embodiment 1, collision between the signal for wireless LAN and the signal for BS 12-2 can be appropriately avoided.

[0050] Embodiment 3 Next, a third embodiment of the present disclosure will be described with reference to Fig. 10. Fig. 10 is a diagram illustrating the configuration and features of a wireless communication system according to the third embodiment of the present disclosure. The system shown in Fig. 10 is similar to the system according to the second embodiment, except that wireless device 10-3 is replaced with wireless device 10-4. In Fig. 10, elements that are the same as those shown in Fig. 8 are denoted by the same reference numerals, and their description will be omitted or simplified.

[0051] 10 shows, more specifically, how the wireless device 10-4 transmits the identification signal 54, followed by an interval 56 of T seconds, and then transmits the BS signal 52. That is, in this embodiment, the wireless device 10-4 transmits a BS signal 12-3 that includes, in that order, the preamble signal 50, the identification signal 54, the interval 56, and the BS signal 52.

[0052] When the BS device 16-2 receives the BS signal 12-3, it determines whether the signal is addressed to it based on the identification signal 54. If the identification signal 54 designating the BS device 16-2 is recognized, the BS device 16-2 starts generating the modulated signal 14. If there is no interval 56 between the identification signal 54 and the BS signal 52, the BS device 16-2 must determine whether the BS signal 12-3 is addressed to it while receiving the identification signal 54.

[0053] On the other hand, if interval 56 exists, the above determination only needs to be completed by the end of interval 56. In this case, the responsiveness required of BS device 16-2 can be kept low compared to when interval 56 does not exist. Therefore, according to this embodiment, it is possible to achieve simplification, cost reduction, lower power consumption, etc. of BS device 16-2 compared to embodiment 2.

[0054] Embodiment 4 [Configuration and Features of the Fourth Embodiment] Next, a fourth embodiment of the present invention will be described with reference to Fig. 5 and Fig. 11. The wireless communication system of this embodiment can be realized by the configuration shown in Fig. 5, similar to the first embodiment. However, in this embodiment, wireless device 10 executes the routine shown in Fig. 11 instead of the routine shown in Fig. 6.

[0055] Fig. 11 is a flowchart for explaining the flow of processing executed by the wireless device 10 in this embodiment. Note that in Fig. 11, steps that are the same as those shown in Fig. 6 are given the same reference numerals, and their explanations will be omitted or simplified.

[0056] 11, in this embodiment as well, wireless device 10 executes the processes of step 100 and step 102. That is, wireless device 10 transmits BS signal 12 and receives modulated signal 14. As in the first embodiment, BS signal 12 includes preamble signal 50 and BS signal 52. Therefore, as in the first embodiment, the system of this embodiment can appropriately avoid collision between a wireless LAN signal and BS signal 12.

[0057] In this embodiment, after completing the process of step 102, the wireless device 10 next calculates the time difference between transmitting the BS signal 12 and receiving the modulated signal 14 (step 110). This time difference is the sum of the propagation time of the BS signal 12, the response time of the BS device 16, and the propagation time of the modulated signal 14. Since the response time of the BS device 16 is known, the propagation time of the signal can be determined by knowing this time difference. The propagation time of the signal corresponds to the distance between the wireless device 10 and the BS device 16. Therefore, the wireless device 10 can calculate the distance from the wireless device 10 to the BS device 16 from the time difference.

[0058] A plurality of BS devices 16 may be placed at positions with different distances from the radio device 10. In this case, after transmitting the BS signal 12, modulated signals 14 emitted by each of the plurality of BS devices 16 arrive sequentially at the radio device 10. In this case, in step 110, the time difference is calculated for each of the modulated signals 14 arriving sequentially.

[0059] After the time difference has been calculated, the distance between wireless device 10 and BS device 16 is estimated based on the time difference (step 112). If wireless device 10 is receiving multiple modulated signals 14, the distance corresponding to each modulated signal 14 is estimated based on the respective time differences.

[0060] According to the above process, wireless device 10 can combine each received modulated signal 14 with the distance to the BS device 16 that emitted it. Once this combination is known, wireless device 10 can identify which BS device 16 emitted the received modulated signal 14 without having to assign an identifier to each BS device 16. Therefore, according to the wireless communication system of this embodiment, it is possible to use BS communication to more easily achieve more precise data collection than in the first embodiment.

[0061] [Modification of the fourth embodiment] Incidentally, in the above-described fourth embodiment, a case has been described in which a plurality of BS devices 16 are placed at positions at different distances from wireless device 10. However, the present disclosure is not limited to this, and there may be only one BS device 16.

[0062] Furthermore, in the above-described fourth embodiment, the technology for estimating distance based on a time difference is combined with the system of the first embodiment, but the present disclosure is not limited to this. For example, the technology for estimating distance may be combined with the system of the second embodiment, which uses the identification signal 54. In this case, it is possible to have each of the multiple BS devices 16-2 individually return a modulated signal 14, thereby preventing collisions between the multiple modulated signals 14. Furthermore, even if the installation locations of the individual BS devices 16-2 are not known, it is possible to know the distance to each installation location, thereby improving the accuracy of data collection.

[0063] Embodiment 5. [Configuration and Features of Fifth Embodiment] Next, a fifth embodiment of the present disclosure will be described with reference to Fig. 12 and Fig. 13. Fig. 12 is a diagram illustrating the configuration and features of a wireless communication system according to the fifth embodiment of the present disclosure. The system shown in Fig. 12 is similar to the system according to the first embodiment, except that wireless device 10 is replaced with wireless device 10-5. In Fig. 12, elements that are the same as those shown in Fig. 1 are denoted by the same reference numerals, and their description will be omitted or simplified.

[0064] 12, radio device 10-5 in this embodiment includes multiple antennas 24-1 to 24-n. Radio device 10-5 also has the function of receiving modulated signal 14 via multiple antennas 24-1 to 24-n and estimating the direction of arrival of modulated signal 14 by analyzing the phase of each received wave.

[0065] Fig. 13 is a flowchart for explaining the flow of processing executed by wireless device 10-5. Note that in Fig. 13, steps that are the same as those shown in Fig. 6 are given the same reference numerals, and their explanations will be omitted or simplified.

[0066] 13, in this embodiment, wireless device 10 also executes the processes of step 100 and step 102. That is, wireless device 10 transmits BS signal 12 and receives modulated signal 14. As in the first embodiment, BS signal 12 includes preamble signal 50 and BS signal 52. Therefore, as in the first embodiment, the system of this embodiment can appropriately avoid collision between a wireless LAN signal and BS signal 12.

[0067] In this embodiment, after completing the process of step 102, wireless device 10 next estimates the direction of arrival of received modulated signal 14 (step 120). The direction of arrival is estimated based on the phase difference between the signals received by each of multiple antennas 24-1 to 24-n. Modulated signal 14 arrives from the direction of BS device 16 that emitted the signal. Therefore, the direction of arrival estimated in step 120 can be recognized as the installation direction of BS device 16.

[0068] A plurality of BS devices 16 may be placed around the wireless device 10. In this case, after transmitting the BS signal 12, modulated signals 14 emitted by each of the plurality of BS devices 16 may arrive sequentially at the wireless device 10. In this case, in step 120, the direction of arrival is estimated for each of the modulated signals 14 arriving sequentially.

[0069] According to the above process, wireless device 10 can combine each received modulated signal 14 with the installation direction of BS device 16 that emitted it. Once the combination is known, wireless device 10 can identify which BS device 16 emitted the received modulated signal 14 without assigning an identifier to each BS device 16. Therefore, according to the wireless communication system of this embodiment, it is possible to use BS communication to more easily achieve more precise data collection than in the first embodiment.

[0070] [Modification of the fifth embodiment] Incidentally, in the above-described fifth embodiment, a case has been described in which a plurality of BS devices 16 are arranged around the wireless device 10. However, the present disclosure is not limited to this, and there may be only one BS device 16.

[0071] In the above-described fifth embodiment, wireless device 10-5 estimates only the direction of arrival of modulated signal 14 with respect to the installation position of BS device 16. However, the present disclosure is not limited to this. For example, the processing of the fourth embodiment may be combined with the fifth embodiment to cause wireless device 10-5 to estimate both the direction and distance with respect to the installation position of BS device 16.

[0072] Furthermore, in the above-described fifth embodiment, the technology for estimating the direction of arrival is combined with the system of the first embodiment, but the present disclosure is not limited to this. For example, the technology for estimating the direction of arrival may be combined with the system of the second embodiment, which uses the identification signal 54. In this case, it is possible to have each of the multiple BS devices 16-2 individually return a modulated signal 14, thereby preventing collisions between the multiple modulated signals 14. Furthermore, even if the installation locations of the individual BS devices 16-2 are unknown, the installation directions of the individual BS devices 16-2 can be known, thereby improving the accuracy of data collection. [Explanation of symbols]

[0073] 10, 10-2, 10-3, 10-4, 10-5 Radio equipment 12, 12-2, 12-3 BS signal 14 Modulated Signal 16, 16-2 BS device 18 Wireless terminals 20, 30, 40 Control section 24, 24-1~24 Antenna 50 Preamble signal 52 BS signal 54 Identification Signal 56 Interval

Claims

1. a step in which a wireless device having a function as an access point of a wireless LAN transmits a BS signal including a preamble signal specified in the wireless LAN and a BS signal for BS communication; a BS device transmitting a modulated signal generated by obtaining driving power from the BS signal; a step of processing the modulated signal by a wireless device receiving the modulated signal; a step in which a wireless terminal having a function of restricting data transmission by a CSMA / CA method restricts data transmission in response to the preamble signal. There are a plurality of the BS devices, calculating a time difference between when the wireless device transmits the BS signal and when the wireless device receives the modulated signal; estimating a distance between the wireless device and a BS device that transmitted the modulated signal based on the time difference; associating the modulated signal with the estimated distance; When the BS devices are located at different distances from the wireless device, recognizing from which of the BS devices the modulated signal received by the wireless device is emitted based on the association without assigning an identifier to each of the BS devices; The wireless communication method further includes:

2. a step in which a wireless device having a function as an access point of a wireless LAN transmits a BS signal including a preamble signal specified in the wireless LAN and a BS signal for BS communication; a BS device transmitting a modulated signal generated by obtaining driving power from the BS signal; a step of processing the modulated signal by a wireless device receiving the modulated signal; a step in which a wireless terminal having a function of restricting data transmission by a CSMA / CA method restricts data transmission in response to the preamble signal. There are a plurality of the BS devices, a wireless device for receiving the modulated signal, the wireless device including a plurality of antennas; a step in which the wireless device estimates a direction of arrival of the modulated signal based on a phase difference between the modulated signals received by each of the plurality of antennas; associating the modulated signal with the estimated direction of arrival; When the BS devices are installed at positions with different installation directions from the wireless device, recognizing from which of the plurality of BS devices the modulated signal received by the wireless device is emitted based on the association without assigning an identifier to each of the BS devices; The wireless communication method further includes:

3. 3. The wireless communication method according to claim 1, wherein the radio device that transmits the BS signal and the radio device that receives the modulated signal are separate devices installed at different locations.

4. A wireless device having a function as an access point of a wireless LAN, a wireless communication unit that transmits a BS signal including a preamble signal specified in a wireless LAN and a BS signal for BS communication, and receives a modulated signal generated by a BS device by obtaining drive power from the BS signal; a control unit that controls the wireless communication unit, the control unit causes the wireless communication unit to transmit the BS signal; a process of calculating a time difference between when the wireless communication unit transmits the BS signal and when the wireless communication unit receives the modulated signal; a process of estimating a distance between the wireless device and the BS device that transmitted the modulated signal based on the time difference; correlating the modulated signal with the estimated distance; When a plurality of the BS devices are arranged at positions with different distances from the wireless device, a process of recognizing which of the plurality of BS devices the received modulated signal is emitted from based on the association without assigning an identifier to each of the BS devices; 10. A wireless communication device configured to:

5. A wireless device having a function as an access point of a wireless LAN, a wireless communication unit that transmits a BS signal including a preamble signal specified in a wireless LAN and a BS signal for BS communication, and receives a modulated signal generated by a BS device by obtaining drive power from the BS signal; a control unit that controls the wireless communication unit; a plurality of antennas for receiving the modulated signals; the control unit causes the wireless communication unit to transmit the BS signal; a process of estimating an arrival direction of the modulated signal based on a phase difference between the modulated signals received by each of the plurality of antennas; correlating the modulated signal with the estimated direction of arrival; When the BS devices are installed at multiple locations with different installation directions from the wireless device, a process of recognizing which of the multiple BS devices the received modulated signal is from based on the association without assigning an identifier to each of the BS devices; 10. A wireless communication device configured to:

6. A wireless communication system comprising: a wireless device that functions as an access point of a wireless LAN; a BS device that transmits a modulated signal generated by obtaining drive power from a BS signal; and a wireless terminal that has a function of restricting data transmission by a CSMA / CA method, There are a plurality of the BS devices, The wireless device A process of transmitting a BS signal including a preamble signal specified in a wireless LAN and a BS signal for BS communication, and receiving the modulated signal; A process of calculating a time difference between transmitting the BS signal and receiving the modulated signal; a process of estimating a distance between the wireless device and the BS device that transmitted the modulated signal based on the time difference; correlating the modulated signal with the estimated distance; When a plurality of the BS devices are arranged at positions with different distances from the wireless device, a process of recognizing which of the plurality of BS devices the received modulated signal is emitted from based on the association without assigning an identifier to each of the BS devices; 1. A wireless communication system configured to:

7. A wireless communication system comprising: a wireless device that functions as an access point of a wireless LAN; a BS device that transmits a modulated signal generated by obtaining drive power from a BS signal; and a wireless terminal that has a function of restricting data transmission by a CSMA / CA method, There are a plurality of the BS devices, The wireless device a plurality of antennas for receiving the modulated signals; A process of transmitting a BS signal including a preamble signal specified in a wireless LAN and a BS signal for BS communication, and receiving the modulated signal; a process of estimating an arrival direction of the modulated signal based on a phase difference between the modulated signals received by each of the plurality of antennas; correlating the modulated signal with the estimated direction of arrival; When the BS devices are installed at multiple locations with different installation directions from the wireless device, a process of recognizing which of the multiple BS devices the received modulated signal is from based on the association without assigning an identifier to each of the BS devices; 1. A wireless communication system configured to:

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