Terminal, method, and program

Abstract

To improve a method for acquiring location information.SOLUTION: A communication system (3970) includes a plurality of cameras (3971A, etc.) that capture images to generate images, a server (3972) that stores the images generated by the plurality of cameras (3971A, etc.), and a plurality of transmission devices (3971A, etc.) that correspond one to-one with the plurality of cameras (3973A, etc.), each of the plurality of transmission devices (3973A, etc.) transmitting light including, as a visible-light communication signal, communication-related information for accessing a storage location in the server in which the image generated by the camera corresponding to the transmission device is stored.SELECTED DRAWING: Figure 39A

Description

[Technical Field]

[0001] The present invention relates to a terminal, a method, and a program. [Background technology]

[0002] One method for devices to obtain location information is to use the Global Positioning System (GPS), in which the device receives modulated signals transmitted from satellites and performs positioning calculations to estimate its location.

[0003] However, if the device is indoors, where it is difficult to receive radio waves transmitted by GPS satellites, there is a problem in that it is difficult to estimate the location.

[0004] As a method for solving this problem, for example, as shown in Non-Patent Document 1, there is a method in which a device estimates its location using radio waves transmitted from an access point of a wireless LAN (Local Area Network). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] “NGP use case document,”IEEE802.11-16 / 0137r4,March 2016.https: / / mentor.ieee.org / 802.11 / dcn / 16 / 11-16-0137-04-00az-ngp-use-case-document.pptx [Non-patent document 2] H. Koga, N. Kodama, and T. Konishi, “High-speed power line communication system based on wavelet OFDM,” Proc. of ISPLC 2003. [Non-patent document 3] S. Galli, H. Koga, and N. Kodama, “Advanced signal processing for PLCs: Wavelet-OFDM,” Proc. of 2008 IEEE International Symposium on Power Line Communications and Its Applications. Summary of the Invention [Problem to be solved by the invention]

[0006] However, since it is not easy to know the SSID (service set identifier) ​​of an access point that can be accessed securely, when a device attempts to obtain location information, there is a possibility that it will connect to an access point with an insecure SSID, which poses the risk of information leakage.

[0007] Thus, there is a demand for further improvements in the method of acquiring location information. [Means for solving the problem]

[0008] A terminal according to one aspect of the present disclosure comprises an optical communication device that receives received optical signals from among a plurality of optical signals transmitted by each of a plurality of transmitting devices, the plurality of optical signals having intensity modulated by transmission data including access information for accessing image data captured by a camera corresponding to the transmitting device that transmitted the optical signals, and a wireless communication device that receives the image data based on the access information obtained from the optical signals received by the optical communication device, and the terminal acquires image data corresponding to the camera from which the user wishes to view the image data by pointing an optical receiving unit at the optical signal corresponding to the camera from among the plurality of optical signals.

[0009] These comprehensive or specific aspects may be realized as a system, a method, 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 a system, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0010] The present disclosure may provide an improved method for obtaining location information. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of devices and terminals. [Figure 2] FIG. 2 is a diagram showing an example of a frame structure transmitted in a modulated signal transmitted by a device. [Figure 3] FIG. 3 is a diagram showing an example of a configuration in which a plurality of devices exist. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of a device, a terminal, and a base station that communicates with the terminal. [Figure 5] FIG. 5 is a diagram showing a specific example of a display on the display unit. [Figure 6] FIG. 6 is a diagram illustrating an example of a frame configuration of a modulated signal transmitted by a device. [Figure 7] FIG. 7 is a diagram illustrating an example of a frame configuration of a modulated signal transmitted by a base station. [Figure 8] FIG. 8 is a flowchart showing an example of processing performed by the device, the terminal, and the base station. [Figure 9] FIG. 9 is a diagram showing a specific example of a display on the display unit. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of a communication system. [Figure 11] FIG. 11 is a diagram illustrating an example of a frame configuration of a modulated signal transmitted by a device. [Figure 12] FIG. 12 is a diagram illustrating an example of a frame configuration of a modulated signal transmitted by a wireless device. [Figure 13] FIG. 13 is a flowchart showing an example of processing performed by the device, the terminal, and the base station. [Figure 14] FIG. 14 is a diagram illustrating an example of the configuration of a device, a terminal, and a base station that communicates with the terminal. [Figure 15] FIG. 15 is a diagram illustrating an example of a frame configuration of a modulated signal transmitted by a device. [Figure 16] FIG. 16 shows an example of a frame structure of a modulated signal transmitted by a device. [Figure 17] FIG. 17 is a flowchart showing a first example of processing performed by the device, the terminal, and the base station. [Figure 18] FIG. 18 is a flowchart showing a second example of the process performed by the device, the terminal, and the base station. [Figure 19] FIG. 19 is a diagram showing an example of the space. [Figure 20] FIG. 20 is a diagram illustrating an example of the configuration of a communication system. [Figure 21] FIG. 21 is a flowchart showing an example of processing performed by a part related to visible light, etc., a terminal, and a wireless device of a base station. [Figure 22] FIG. 22 is a diagram illustrating an example of the configuration of a communication system. [Figure 23] FIG. 23 is a diagram illustrating an example of the frame structure of a modulated signal transmitted by a device. [Figure 24] FIG. 24 is a diagram illustrating an example of the frame structure of a modulated signal transmitted by a device. [Figure 25] FIG. 25 is a diagram illustrating an example of the frame structure of a modulated signal transmitted by a device. [Figure 26] FIG. 26 is a diagram illustrating an example of a transmission method when a device transmits a plurality of frames. [Figure 27] FIG. 27 is a diagram showing an example of an area. [Figure 28] FIG. 28 is a flowchart showing an example of processing performed by the device, the terminal, and the base station. [Figure 29] FIG. 29 is a diagram illustrating an example of the configuration of a device related to the transmission of an optically modulated signal. [Figure 30] FIG. 30 is a diagram showing an example of the configuration of a device related to the transmission of an optically modulated signal. [Figure 31] FIG. 31 is a diagram illustrating an example of the configuration of a transmitting device and a receiving device. [Figure 32] FIG. 32 is a diagram illustrating an example of the configuration of a transmitting device and a receiving device. [Figure 33] FIG. 33 is a diagram showing an example of the configuration of a device related to the transmission of an optically modulated signal. [Figure 34] FIG. 34 is a diagram showing an example of the configuration of a device related to an optical modulation signal. [Figure 35] FIG. 35 is a diagram illustrating an example of the configuration of a transmitting device related to an optical modulated signal. [Figure 36A] FIG. 36A is a diagram illustrating an example of the configuration of a transmitting device related to an optical modulated signal. [Figure 36B] FIG. 36B is a diagram showing an example of the configuration of a car. [Figure 36C] FIG. 36C is a diagram showing an example of the configuration of a car. [Figure 36D] FIG. 36D is a diagram showing an example of a communication method between a transmitting device and a receiving device. [Figure 36E] FIG. 36E is a diagram illustrating an example of a visible light communication method. [Figure 36F] FIG. 36F is a diagram showing an example of a light emission pattern of a light source and a captured image. [Figure 36G] FIG. 36G is a diagram showing an example of a light emission pattern of a light source and a captured image. [Figure 36H] FIG. 36H is a diagram showing an example of a modulation method. [Figure 36I] FIG. 36I is a diagram showing an example of a modulation method. [Figure 37] FIG. 37 shows a system made up of communication devices. [Figure 38] FIG. 38 is a flowchart showing an example of processing performed by the terminal, the base station, and the server. [Figure 39A] FIG. 39A is a diagram showing a first example of a system related to a moving image providing method using an optical modulation signal. [Figure 39B] FIG. 39B is a flow diagram showing an example of processing related to a moving image providing method using an optical modulation signal. [Figure 39C] FIG. 39C is a diagram showing a second example of a system related to a moving image providing method using an optical modulation signal. [Figure 40] FIG. 40 shows an example of a stadium scene. [Figure 41] FIG. 41 is a diagram showing an example of the operation flow of the camera, the transmitting device, and the server. [Figure 42] FIG. 42 is a diagram illustrating an example of the operation flow of the terminal, the transmitting device, and the communication device. [Figure 43] FIG. 43 is a diagram illustrating an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. [Figure 44] FIG. 44 is a diagram illustrating an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. [Figure 45] FIG. 45 is a diagram illustrating an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. [Figure 46] FIG. 46 is a diagram illustrating an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. [Figure 47] FIG. 47 is a diagram illustrating an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. [Figure 48] FIG. 48 is a diagram illustrating an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. [Figure 49] FIG. 49 is a diagram illustrating an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. [Figure 50] FIG. 50 is a diagram showing an example of a frame configuration of an optically modulated signal transmitted by a transmitting device. DETAILED DESCRIPTION OF THE INVENTION

[0012] A terminal according to one aspect of the present invention comprises an optical communication device that receives received optical signals from among a plurality of optical signals transmitted by each of a plurality of transmitting devices, the plurality of optical signals having intensity modulated by transmission data including access information for accessing image data captured by a camera corresponding to the transmitting device that transmits the optical signals, and a wireless communication device that receives the image data based on the access information obtained from the optical signals received by the optical communication device, and the terminal acquires image data corresponding to the camera from which the user wishes to view the image data by pointing an optical receiving unit at the optical signal corresponding to the camera from among the plurality of optical signals.

[0013] Furthermore, a method according to one aspect of the present invention is a method executed by a terminal, which receives received optical signals from among a plurality of optical signals transmitted by each of a plurality of transmitting devices, the plurality of optical signals having intensities modulated by transmission data including access information for accessing image data captured by a camera corresponding to the transmitting device transmitting the optical signals, receives the image data based on the access information obtained from the received optical signals, and acquires image data corresponding to the camera by directing a light receiving unit provided in the terminal toward the optical signal corresponding to the camera from which the user wishes to view the image data from among the plurality of optical signals.

[0014] A terminal according to one embodiment of the present invention is a terminal comprising: an optical communication device that receives an optical signal transmitted by a first transmitting device among a plurality of transmitting devices, the optical signal having its intensity modulated by transmission data including access information for accessing image data captured by a camera corresponding to the first transmitting device; a user interface that selects the optical signal from a plurality of optical signals transmitted by the plurality of transmitting devices; and a wireless communication device that receives the image data based on the access information obtained from the optical signal received by the optical communication device and selected by the user interface.

[0015] Furthermore, a method according to one aspect of the present invention is a method executed by a terminal, which receives an optical signal transmitted by a first transmitting device among a plurality of transmitting devices, the optical signal having its intensity modulated by transmission data including access information for accessing image data captured by a camera corresponding to the first transmitting device, selects the optical signal from a plurality of optical signals transmitted by the plurality of transmitting devices, and receives the image data based on the access information obtained from the selected optical signal among the received optical signals.

[0016] A communication system according to one embodiment of the present invention includes a plurality of cameras that generate image data by capturing images, a server in which the image data generated by each of the plurality of cameras is stored, and a plurality of transmitting devices that correspond one-to-one to the plurality of cameras, each transmitting light including, as a visible light communication signal, information regarding communication for accessing a storage location in the server where the image data generated by the camera corresponding to that transmitting device is stored.

[0017] According to the above aspect, the communication system can provide the terminal with information relating to communication for accessing the storage location of the image data more safely, and the terminal can acquire the location information more safely.

[0018] More specifically, the communication system transmits an (optically) modulated signal containing location-related information from a visible light, illumination, light source, or light, such as an LED (Light Emitting Diode) installed indoors. The terminal (device) receives the (optically) modulated signal using an image sensor, such as a CMOS (Complementary Metal Oxide Semiconductor) or an OPF (Organic Photoconductive Film) CMOS (organic CMOS), and performs processing such as demodulation to obtain at least location-related information, thereby achieving the effect of allowing the terminal to safely obtain location-related information.

[0019] For example, the information includes address information indicating the storage location where the image data is stored.

[0020] According to the above aspect, the communication system can acquire location information more easily and safely by transmitting address information by visible light communication.

[0021] For example, the information includes an encryption key used to encrypt communications for a terminal to access the storage location where the image data is stored.

[0022] According to the above aspect, the communication system can acquire location information more easily and safely by transmitting the encryption key by visible light communication.

[0023] For example, the information includes an identifier of a wireless communication base station for a terminal to access the storage location where the image data is stored.

[0024] According to the above aspect, the communication system can acquire location information more easily and safely by transmitting the identifier of the base station by visible light communication.

[0025] For example, the information includes location information indicating the location where the image data was captured.

[0026] According to the above aspect, the communication system can acquire location information more easily and safely by transmitting the location information of the image capture location by visible light communication.

[0027] A terminal according to one aspect of the present invention includes a receiving device that receives light containing information indicating a storage location of image data as a visible light communication signal, and a transmitting / receiving device that receives the image data from the storage location indicated by the information received by the receiving device.

[0028] According to the above aspect, the terminal can acquire location information more safely.

[0029] A control method for a communication system according to one embodiment of the present invention is a control method for a communication system, the communication system comprising a plurality of cameras, a server, and a plurality of transmitting devices each corresponding to the plurality of cameras, wherein image data is generated by capturing images using the plurality of cameras, the image data generated by each of the plurality of cameras is stored on the server, and each of the plurality of transmitting devices transmits light as a visible light communication signal containing information regarding communication for accessing a storage location in the server where the image data generated by the camera corresponding to the transmitting device is stored.

[0030] This provides the same effects as the above-mentioned communication system.

[0031] A method for controlling a terminal according to one aspect of the present invention is a method for controlling a terminal, which receives light containing information indicating a storage location of image data as a visible light communication signal, and receives the image data from the storage location indicated by the received information.

[0032] This provides the same effect as the above terminal.

[0033] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM (Compact Disc Read Only Memory), or may be realized as any combination of a system, a method, an integrated circuit, a computer program, or a recording medium.

[0034] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0035] The embodiments described below are all comprehensive or specific examples. 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 invention. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concepts are described as optional components.

[0036] (Embodiment 1) 1 shows an example of the configuration of device 100 and terminal 150 in this embodiment, each of which includes a visible light source, illumination, light source, or light, such as an LED (Light Emitting Diode). Device 100 includes a visible light source, illumination, light source, or light, such as an LED (Light Emitting Diode). This device will be referred to as a "first device."

[0037] The transmitting unit 102 receives, for example, information about a location or information about a position 101. The transmitting unit 102 may also receive, as input, information about a time 105. The transmitting unit 102 may also receive, as input, information about a location or both information about a position 101 and information about a time 105.

[0038] The transmitter 102 receives location-related or position-related information 101 and / or time-related information 105 as input, generates an (optical) modulated signal based on these input signals, and outputs modulated signal 103. The modulated signal 103 is then transmitted from a light source 104, for example.

[0039] Here, an example of the location-related or position-related information 101 will be described.

[0040] (Example 1) The location-related information or position-related information 101 may be information on the latitude and / or longitude of the location / position. For example, information such as "45 degrees north latitude, 135 degrees east longitude" may be the location-related information or position-related information 101.

[0041] (Example 2) The information about the place or the information about the position 101 may be address information. For example, information such as "Tokyo and 1-1-1 XX-cho, Chiyoda-ku" may be the information about the place or the information about the position 101.

[0042] (Example 3) The information 101 relating to a place or a position may be information relating to a building, a facility, etc. For example, information such as "Tokyo Tower" may be the information 101 relating to a place or a position.

[0043] (Example 4) The information about the location or the information about the position 101 may be information about the specific location or position of an object installed in a building, facility, or the like.

[0044] For example, suppose there is a parking lot with spaces for five cars. In this case, the first parking space is named A-1, the second parking space is named A-2, the third parking space is named A-3, the fourth parking space is named A-4, and the fifth parking space is named A-5. Then, for example, information such as "A-3" may be information about a location or information 101 about a position.

[0045] This isn't just a parking lot situation.

[0046] For example, information about the "area, seat, store, facility, etc." at concert facilities, stadiums for baseball, soccer, tennis, etc., airplanes, airport lounges, train stations, etc. may be used as information about place or information about location 101.

[0047] The method of configuring the location-related information or the position-related information 101 is not limited to the above example.

[0048] Terminal 150 receives the modulated signal transmitted by first device 100 .

[0049] The light receiving unit 151 is, for example, an image sensor such as a CMOS or an organic CMOS. The light receiving unit 151 receives light including a modulated signal output from the first device and outputs a received signal 152. The receiving unit 153 receives the received signal 152 as input, performs processing such as demodulation and error correction decoding on the modulated signal included in the received signal, and outputs received data 154.

[0050] It should be noted that the received signal 152 output from the light receiving unit 151 may be a signal containing information about an image or video captured by an image sensor, or may be an output signal from another element that performs optical-to-electrical conversion (converts light to an electrical signal). In the following description, when it is stated that the receiving device receives a modulated signal without specifically explaining the processing performed by the light receiving unit 151, this means that the receiving device performs optical-to-electrical conversion (converts light to an electrical signal) from light containing the modulated signal using the light receiving unit 151, thereby obtaining an "image / video signal" and a "modulated signal for transmitting information." However, the above-mentioned method is one example of a method by which the receiving device receives a modulated signal, and the method of receiving a modulated signal is not limited to this.

[0051] Data analysis unit 155 receives received data 154 as input, estimates the location and position of terminal 150 from received data 154 , and outputs information 156 including at least the location and position information of terminal 150 .

[0052] The display unit 157 receives the information 156 as an input, and displays information relating to the location and position of the terminal 150 on the display unit 157 based on the location and position information of the terminal 150 included in the information 156 .

[0053] 2 shows an example of a frame structure transmitted in a modulated signal transmitted by first device 100. In FIG. 2, the horizontal axis represents time. The first device transmits, for example, preamble 201, followed by control information symbol 202, location information or position information symbol 203, and time information symbol 204.

[0054] In this case, preamble 201 is assumed to be a symbol used by terminal 150 receiving the modulated signal transmitted by first device 100 to perform, for example, signal detection, time synchronization, frame synchronization, and the like.

[0055] The control information symbols 202 are assumed to be symbols containing data such as the modulation signal configuration method, the error correction coding method used, and the frame configuration method.

[0056] The symbols 203 relating to location information or position information are symbols including information relating to the location or position shown in FIG.

[0057] The frame may also include symbols other than symbols 201, 202, and 203. For example, as shown in Fig. 2, it may also include symbol 204 relating to time information. Symbol 204 relating to time information is assumed to include, for example, information on the time at which the first device transmits the modulated signal. Note that the frame configuration of the modulated signal transmitted by the first device is not limited to that shown in Fig. 2, and the symbols included in the modulated signal are not limited to that shown in Fig. 2 (symbols including other data and information may also be included).

[0058] As explained in FIG. 1 and FIG. 2, the effect when the first device transmits a modulated signal and the terminal receives the modulated signal will be explained.

[0059] Because the first device transmits a modulated signal using visible light, a terminal capable of receiving this modulated signal is not located far from the location of the first device. Therefore, by obtaining the location and position information transmitted by the first device, the terminal can easily obtain highly accurate position information (without complex signal processing). Furthermore, if the first device is installed in a location where it is difficult to receive satellite radio waves from GPS, the terminal can safely obtain highly accurate position information by receiving the modulated signal transmitted by the first device, even in a location where it is difficult to receive radio waves from GPS satellites.

[0060] (Embodiment 2) In this embodiment, an embodiment in which a plurality of first devices as described in the first embodiment exist will be described.

[0061] In this embodiment, as shown in Fig. 3, for example, 1-1 device 301-1, which has a configuration similar to that of 1st device 100 in Fig. 1, transmits a modulated signal, which is received by terminal 302. Terminal 302 receives the modulated signal transmitted by 1-1 device 301-1, and obtains, for example, information about the location and position of 1-1 and information about the time of 1-1.

[0062] Similarly, the first device 301-2, which has the same configuration as the first device 100 in Fig. 1, transmits a modulated signal, which is received by the terminal 302. The terminal 302 receives the modulated signal transmitted by the first device 301-2, and obtains, for example, information about the location and position of the first device 301-2 and information about the time of the first device 301-2.

[0063] Then, terminal 302 can know the distance between 1-1 device 301-1 and 1-2 device 301-2 in FIG. 3 from information about the location and position of 1-1 and information about the location and position of 1-2. Then, terminal 302 can know the distance between terminal 302 and 1-1 device 301-1 based on information about the time of 1-1 and, for example, the time when terminal 302 received the modulated signal transmitted by 1-1 device 301-1. Similarly, terminal 302 can know the distance between terminal 302 and 1-2 device 301-2 based on information about the time of 1-2 and, for example, the time when terminal 302 received the modulated signal transmitted by 1-2 device 301-2.

[0064] Then, terminal 302 knows the location of device 1-1 from the information about the location and position of device 1-1. Terminal 302 knows the location of device 1-2 from the information about the location and position of device 1-2. Terminal 302 knows the "triangle formed by device 1-1 301-1, device 1-2 301-2, and terminal 302" from the "distance between device 1-1 301-1 and device 1-2 301-2," "distance between device 1-1 301-1 and the terminal," and "distance between device 1-2 301-2 and the terminal."

[0065] Therefore, terminal 302 can calculate and obtain its position with high accuracy from "the position of device 1-1," "the position of device 1-2," and "the triangle formed by device 1-1 301-1, device 1-2 301-2, and terminal 302."

[0066] However, the geodetic surveying method by which the terminal 302 obtains location and position information is not limited to the above description, and any method of geodetic surveying may be used, such as triangulation, polygonal surveying, trilateration, and leveling.

[0067] As described above, by the terminal obtaining the above-mentioned information from a plurality of devices equipped with light sources that transmit location information, the terminal can obtain the effect of being able to estimate its location with high accuracy. Furthermore, as described in the first embodiment, if the device equipped with a light source that transmits location information is installed in a location where it is difficult to receive satellite radio waves from GPS, the terminal can obtain the effect of being able to safely obtain highly accurate location information by receiving the modulated signal transmitted by the device even in a location where it is difficult to receive radio waves from GPS satellites.

[0068] In the above example, the terminal receives modulated signals transmitted from two devices, but the present invention can be implemented in the same way even when the terminal receives modulated signals transmitted from more than two devices. The greater the number of devices, the more accurate the terminal can calculate location information.

[0069] (Embodiment 3) FIG. 4 shows an example of the configuration of a device equipped with a light source of visible light such as an LED, illumination, a light source, and a light, and a base station that communicates with the device, for example, in this embodiment. Device 400 in FIG. 4 is equipped with a light source of visible light such as an LED, illumination, a light source, and a light. This device is referred to as a "first device." In first device 400 in FIG. 4, components that operate in the same manner as first device 100 in FIG. 1 are assigned the same reference numerals.

[0070] A terminal 450 in FIG. 4 shows the configuration of the terminal, and components that operate in the same manner as in FIG. 1(b) are given the same reference numerals.

[0071] 4, transmitter 101 receives, as input, for example, location-related information or position-related information 101, SSID (service set identifier) ​​information 401-1, and access destination information 401-2. Transmitting unit 101 may also receive time-related information 105.

[0072] The transmitter 102 receives as input information about the location or position 101, information about the SSID 401-1, information about the access destination 401-2, and / or information about the time 105, generates an (optical) modulated signal based on these input signals, and outputs modulated signal 103. Then, modulated signal 103 is transmitted from a light source 104, for example.

[0073] Note that examples of the information about the location or the information about the position 101 have been explained in the first embodiment, so explanations thereof will be omitted here.

[0074] Next, the information 401-1 relating to the SSID and the information 401-2 relating to the access destination will be described.

[0075] First, the information 401-1 regarding the SSID will be explained.

[0076] The SSID information 401-1 is information on the SSID of the base station (or AP (access point)) 470 in FIG. 4. If it is determined that the SSID notified by the optical signal is the SSID of a safe base station, the first device 400 can provide the terminal 450 with access to the base station 470, which is a safe access destination. This provides the effect that the terminal 450 in FIG. 4 can safely obtain information from the base station (or AP) 470. On the other hand, the first device 400 can limit the terminals that access the base station 470 to terminals in a space that can receive the optical signal transmitted (irradiated) by the first device 400.

[0077] When receiving an optical signal transmitted in a predetermined manner, the terminal 450 may determine that the notified SSID is the SSID of a secure base station, or may perform a process to determine whether the SSID is secure. For example, the first device 400 may transmit an optical signal including a predetermined identifier, and the terminal may determine whether the notified SSID is the SSID of a secure base station based on the received identifier. Alternatively, the terminal 450 may not perform a process to determine whether the base station is secure, but may instead use the characteristics of visible light to allow the user to select a highly secure first device 400, and have the terminal 450 receive an optical signal from the first device 400 to obtain the SSID of the highly secure base station.

[0078] Although only base station (or AP) 470 is shown in FIG. 4, even if there is a base station (or AP) other than base station (or AP) 470, terminal 450 in FIG. 4 will access base station (or AP) 470 to obtain information.

[0079] Information 401-2 on the access destination is information on the access destination for terminal 450 in Fig. 4 to access base station (or AP) 470 and then obtain information. (Note that a specific example of the operation will be described later.)

[0080] Terminal 450 in Fig. 4 receives the modulated signal transmitted by first device 400. In terminal 450 in Fig. 4, components that operate in the same manner as terminal 150 in Fig. 1 are assigned the same reference numerals.

[0081] The terminal 450 has a light receiving unit 151, such as an image sensor including a CMOS or organic CMOS, which receives the modulated signal transmitted by the first device 400. The receiving unit 153 receives the received signal 152 received by the light receiving unit 151 as input, performs processing such as demodulation and error correction decoding of the received signal, and outputs received data 154.

[0082] The data analysis unit 155 receives the received data 154 as input, estimates the location and position of the terminal from the received data 154, and outputs information 156 including at least the location and position information of the terminal, information 451 regarding the SSID, and information 452 regarding the access destination.

[0083] Display unit 157 receives information 156 including the location and position information of the terminal, information 451 related to the SSID, and information 452 related to the access destination, and displays, for example, the location and position of the terminal, the SSID of the communication partner accessed by wireless device 453 included in terminal 450, and the access destination. (This display is called the first display.)

[0084] For example, after the first display, wireless device 453 included in terminal 450 in Fig. 4 receives information 451 about the SSID and information 452 about the access destination. Then, wireless device 453 included in terminal 450 in Fig. 4 connects to the other party with which to communicate, for example, by using radio waves, based on information 451 about the SSID. In the case of Fig. 4, wireless device 453 included in terminal 450 in Fig. 4 connects to base station 470.

[0085] Then, the wireless device 453 provided in the terminal 450 in FIG. 4 generates a modulated signal from data including information about the access destination based on the information 452 about the access destination, and transmits this modulated signal to the base station 451, for example, using radio waves.

[0086] Base station (or AP) 470, which is the communication partner of the terminal in Fig. 4(b), receives the modulated signal transmitted by wireless device 453 included in terminal 450 in Fig. 4. Then, base station (or AP) 470 performs processes such as demodulation and error correction decoding of the received modulated signal, and outputs received data 471 including information on the access destination transmitted by terminal 450 in Fig. 4. Based on this information on the access destination, base station (or AP) 470 accesses the desired access destination via the network and obtains, for example, desired information 472 from the access destination.

[0087] Base station 470 receives desired information 472 as input, generates a modulated signal from desired information 472, and transmits this modulated signal to terminal 450 in FIG. 4 using, for example, radio waves.

[0088] Radio equipment 453 of terminal 450 in FIG. 4 receives the modulated signal transmitted by base station 470, and performs processing such as demodulation and error correction decoding to obtain desired information 472.

[0089] For example, the desired information 472 may be a map, a building map or floor guide, a facility map or floor guide, a parking lot map or floor guide, or information on "areas, seats, stores, and facilities" in a concert facility, stadium, airplane, airport lounge, train station, etc.

[0090] Display unit 157 receives desired information 472, information 156 including at least the location and position information of the terminal, and information 451 related to the SSID as input, and after a first display, displays a map, floor guide, facility information, seat information, and store information in which the location of the terminal is mapped from desired information 472 and information 156 including at least the location and position information of the terminal.

[0091] A specific example of this will be shown below. FIG. 5 is an example of a specific display on the display unit 157. The display in FIG. 5 indicates "the third floor." A-1, A-2, A-3, A-4, A-21, A-22, A-23, and A-24 indicate the locations of car parking spaces, respectively. A-1 and A-2 indicate the location of the elevator. This map information is assumed to be desired information 453. As shown in FIG. 5, the current location is mapped and displayed on the map. In this case, the current location is information obtained from information 156 including at least the location and position information of the terminal.

[0092] Fig. 6 shows an example of the frame structure of a modulated signal transmitted by first device 400 in Fig. 4. In Fig. 6, the horizontal axis represents time, and symbols transmitting the same information as in Fig. 2 are assigned the same reference numerals, and their explanations will be omitted.

[0093] The first device 400 transmits a preamble 201, a control information symbol 202, a symbol 203 relating to location information or position information, a symbol 204 relating to time information, as well as a symbol 600-1 relating to the SSID and a symbol 600-2 relating to the access destination.

[0094] Note that symbol 600-1 relating to the SSID is a symbol for transmitting information 401-1 relating to the SSID in Fig. 4, and symbol 600-2 relating to the access destination is a symbol for transmitting information 401-2 relating to the access destination in Fig. 4. Note that the frame in Fig. 6 may include symbols other than those shown in Fig. 6. Also, the frame configuration, including the order in which the symbols are transmitted, is not limited to the configuration in Fig. 6.

[0095] Fig. 7 shows an example of a frame structure of a modulated signal transmitted by base station 470 in Fig. 4, with the horizontal axis representing time. As shown in Fig. 7, base station 470 transmits, for example, preamble 701, followed by control information symbol 702 and information symbol 703.

[0096] In this case, preamble 701 is assumed to be a symbol used by a terminal receiving a modulated signal transmitted by base station 470 to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, frequency offset estimation, and the like.

[0097] The control information symbol 702 includes data such as the error correction coding method used to generate the modulated signal, information about the modulation method, and information about the frame structure.

[0098] Information symbols 703 are symbols for transmitting information. In this embodiment, information symbols 703 are symbols for transmitting desired information 472 described above.

[0099] Note that base station 470 in FIG. 4 may transmit a frame including symbols other than those shown in FIG. 7 (for example, a frame including a pilot symbol (reference symbol) in the middle of information symbols). Also, the frame configuration, including the order in which symbols are transmitted, is not limited to that in FIG. 7. In FIG. 7, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0100] Also, for example, the modulated signal having the frame structure shown in Figure 6 transmitted by the first device may be transmitted at regular intervals, for example, repeatedly, thereby enabling multiple terminals to perform the operations described above.

[0101] FIG. 8 is a flowchart showing an example of the processing performed by the "first device 400," "terminal 450," and "base station (or AP) 470" in FIG. 4 described above.

[0102] First, as shown in 801 in FIG. 8, first device 400 in FIG. 4 transmits a modulated signal having the frame structure shown in FIG.

[0103] Then, as in 802 of FIG. 8, the modulated signal transmitted by the first device 400 of FIG. 4 is received, and the terminal 450 of FIG. 4 estimates the location and position of the terminal.

[0104] At the same time, as shown in 803 in FIG. 8, the modulated signal transmitted by first device 400 in FIG. 4 is received, and terminal 450 in FIG. 4 learns the SSID of the base station that the terminal accesses.

[0105] Then, as in 804 of FIG. 8, terminal 450 of FIG. 4 transmits a modulated signal including data regarding the access destination to obtain information such as a map to base station (or AP) 470 of FIG. 4, for example, using radio waves.

[0106] As shown in 805 of FIG. 8, the base station (or AP) 470 receives the modulated signal transmitted by the terminal 450, obtains information about the destination, and then accesses the desired destination via the network to obtain the desired information, such as a map.

[0107] 8, the base station (or AP) 470 of FIG. 4 transmits a modulated signal including the desired information, such as the obtained map, to the terminal 450, for example, by radio waves.

[0108] As shown in 807 of Fig. 8, the terminal 450 receives a modulated signal transmitted by the base station (or AP) 470 and obtains map (or other) information. Then, the terminal 450 displays the information as shown in Fig. 5 based on the map (or other) information and the terminal location / position information that has already been obtained.

[0109] Next, an example of operation when a plurality of primary devices 400 and a base station (or AP) 470 are installed at the location shown in FIG. 5 will be described.

[0110] As in Figure 5, Figure 9 shows a map of the location.

[0111] Figure 9 is a map of the "third floor" as explained in Figure 5. A-1, A-2, A-3, A-4, A-21, A-22, A-23, and A-24 are car parking spaces, and A-1 and A-2 indicate elevators.

[0112] Then, a first device having a configuration similar to device 100 in FIG. 4 is installed at the position of "circle" 901-1 in FIG. 9. The first device having a configuration similar to device 100 in FIG. 4 and located at position 901-1 is called "first device 1." The first device 1 has information "A-1" as information related to a location or a position, and transmits the information "A-1" as information related to a location or a position.

[0113] A first device having a configuration similar to that of device 100 in FIG. 4 is installed at the position of "circle" 901-2 in FIG. 9. The first device having a configuration similar to that of device 100 in FIG. 4 and located at the position of 901-2 is called "first device 2." First device 2 has information "A-2" as information related to a location or a position, and will transmit the information "A-2" as information related to a location or a position.

[0114] A first device having a configuration similar to that of device 100 in Fig. 4 is installed at the position of "circle" 901-3 in Fig. 9. The first device having a configuration similar to that of device 100 in Fig. 4 and located at 901-3 is called "first device 3." The first device 3 has information "A-3" as information related to a location or a position, and will transmit the information "A-3" as information related to a location or a position.

[0115] A first device having a configuration similar to that of device 100 in Fig. 4 is installed at the position of "circle" 901-4 in Fig. 9. The first device having a configuration similar to that of device 100 in Fig. 4 and located at 901-4 is called "first 4th device." The first 4th device has information "A-4" as information related to a location or a position, and will transmit the information "A-4" as information related to a location or a position.

[0116] A first device having a configuration similar to device 100 in Fig. 4 is installed at the position of "circle" 901-21 in Fig. 9. The first device having a configuration similar to device 100 in Fig. 4 at the position 901-21 is named "first device 21." The first device 21 has information "A-21" as information related to a location or a position, and will transmit the information "A-21" as information related to a location or a position.

[0117] A first device having a configuration similar to device 100 in Fig. 4 is installed at the position of "circle" 901-22 in Fig. 9. The first device having a configuration similar to device 100 in Fig. 4 at position 901-22 is named "first device 22." The first device 22 has information "A-22" as information related to the location or position, and will transmit the information "A-22" as information related to the location or position.

[0118] A first device having a configuration similar to device 100 in Fig. 4 is installed at the position of "circle" 901-23 in Fig. 9. The first device having a configuration similar to device 100 in Fig. 4 and located at 901-23 is named "first device 23." The first device 23 has information "A-23" as information related to the location or position, and will transmit the information "A-23" as information related to the location or position.

[0119] A first device having a configuration similar to that of first device 400 in Fig. 4 is installed at the position of "circle" 901-24 in Fig. 9. The first device having a configuration similar to that of first device 400 in Fig. 4 at the position 901-24 is named "first 24 devices." The first 24 devices have information "A-24" as information related to a location or position, and will transmit the information "A-24" as information related to a location or position.

[0120] A base station (or AP) having the same configuration as base station 470 in Fig. 4 is installed at the position of "◎" 902 in Fig. 9. In this case, the SSID of the base station (or AP) having the same configuration as base station 470 in Fig. 4 at the position 902 is "abcdef".

[0121] When a terminal located near the location shown on the map in Fig. 9 wishes to perform wireless communication, it should access a base station (or AP) that has a configuration similar to that of 470 in Fig. 4 and is installed at location 902 in Fig. 9. Therefore, the "first 1 device" installed at 901-1 in Fig. 9 will transmit "abcdef" as information related to the SSID (see 401-1 in Fig. 4).

[0122] Similarly, the "first 2nd device" installed at 901-2 in FIG. 9 will transmit "abcdef" as information about the SSID (see 400-1 in FIG. 4).

[0123] The "first 3rd device" installed at 901-3 in FIG. 9 will transmit "abcdef" as information related to the SSID (see 401-1 in FIG. 4).

[0124] The "first 4th device" installed at 901-4 in FIG. 9 will transmit "abcdef" as information related to the SSID (see 401-1 in FIG. 4).

[0125] The "first 21 devices" installed at 901-21 in FIG. 9 will transmit "abcdef" as information about the SSID (see 401-1 in FIG. 4).

[0126] The "first 22 devices" installed at 901-22 in FIG. 9 will transmit "abcdef" as information about the SSID (see 401-1 in FIG. 4).

[0127] The "first 23 devices" installed at 901-23 in FIG. 9 will transmit "abcdef" as information about the SSID (see 401-1 in FIG. 4).

[0128] The "first 24 devices" installed at 901-24 in FIG. 9 will transmit "abcdef" as information about the SSID (see 401-1 in FIG. 4).

[0129] A specific example of the operation will be described below.

[0130] Assume that a terminal having a configuration similar to that of terminal 450 in FIG. 4 is located at 903-1 in FIG. 9. Then, the terminal receives a modulated signal transmitted by the "first 4th device" located at 901-4 in FIG. 9, and obtains location information of "A-4." The terminal also obtains SSID information of "abcdef," which causes the terminal to access a base station (or AP) located at 902 in FIG. 9, which has a configuration similar to that of base station 470 in FIG. 4, and the terminal obtains information such as a map from the base station (or AP) located at 902 in FIG. 9, which has a configuration similar to that of base station 470 in FIG. 4. The terminal then displays the map information and location information (see FIG. 5; however, FIG. 5 is merely an example of a display).

[0131] Assume that a terminal having a configuration similar to that of terminal 450 in FIG. 4 is located at 903-2 in FIG. 9. Then, the terminal receives a modulated signal transmitted by the "first 22 device" located at 901-22 in FIG. 9, and obtains location information of "A-22." The terminal also obtains SSID information of "abcdef," which allows the terminal to access a base station (or AP) located at 902 in FIG. 9, which has a configuration similar to that of base station 470 in FIG. 4. The terminal obtains information such as a map from the base station (or AP) located at 902 in FIG. 9, which has a configuration similar to that of base station 470 in FIG. 4. The terminal then displays the map information and location information (see FIG. 5; however, FIG. 5 is merely an example of a display).

[0132] In addition, if the terminal stores the map (surrounding area information) and location information as shown in Figure 5 in the memory unit of the terminal and allows the user of the terminal to retrieve this stored information when necessary, the user can more conveniently use the map (surrounding area information) and location information.

[0133] As described above, since the first device transmits a modulated signal using visible light, the terminals that can receive this modulated signal are limited to those within a range from the location of the first device where the signal light can be received. Therefore, by receiving the location and position information transmitted by the first device, the terminal can easily obtain highly accurate position information (without complex signal processing). Furthermore, if the first device is installed in a location where it is difficult to receive satellite radio waves from GPS, the terminal can safely obtain highly accurate position information by receiving the modulated signal transmitted by the first device, even in a location where it is difficult to receive radio waves from GPS satellites.

[0134] Furthermore, the terminal can connect to a base station (or AP) based on the SSID information transmitted from the first device to obtain the information, thereby achieving the effect of enabling the information to be obtained safely. This is because, when the information is obtained from a modulated signal of visible light, the user can easily recognize the first device that transmitted the modulated signal because it is visible light, and can easily determine whether the source of the information is safe.

[0135] For example, if the SSID is obtained from the modulated signal of radio waves transmitted by a wireless LAN, it is difficult for the user to identify the device that transmitted the radio waves. Therefore, in terms of ensuring the security of information, it is more appropriate to obtain the SSID using visible light communication.

[0136] It should be noted that wireless device 453 of terminal 450 in Fig. 4 may further have a plurality of input signals. For example, a control signal for controlling wireless device 453 and information to be transmitted to a base station may exist as input signals. In this case, an example of an operation in which wireless device 453 starts communication based on the control signal is conceivable. As described above, the configuration of the first device is not limited to the configuration of first device 400 in Fig. 4, and the configuration of the terminal is not limited to the configuration of terminal 450 in Fig. 4, and the connection destination and configuration of base station 470 are also not limited to those shown in Fig. 4.

[0137] Also, while FIG. 4 illustrates a case where one base station (or AP) is installed, there may be multiple (secure) base stations (or APs) accessible to the terminal. In this case, the symbol related to the SSID transmitted by first device 400 in FIG. 4 may include information indicating the SSID of each of the multiple base stations (or APs). Then, terminal 450 in FIG. 4 may select a base station (or AP) to wirelessly connect to (or connect to multiple base stations (or APs)) based on the information on the SSIDs of the multiple base stations.

[0138] For example, suppose there are three base stations (or APs). These are named base station #A, base station #B, and base station #C. The SSID of base station #A is "abcdef," the SSID of base station #B is "ghijk," and the SSID of base station #C is "pqrstu." In this case, the SSID-related symbol 600-1 in the frame configuration of the modulated signal transmitted by the first device in FIG. 6 includes information on "the SSID of base station #A is 'abcdef'," "the SSID of base station #B is 'ghijk'," and "the SSID of base station #C is 'pqrstu'." Terminal 450 in FIG. 4 receives the SSID-related symbol 600-1 and selects a base station (or AP) to wirelessly connect to based on the information on "the SSID of base station #A is 'abcdef'," "the SSID of base station #B is 'ghijk'," and "the SSID of base station #C is 'pqrstu'."

[0139] (supplement) Naturally, the embodiments and other contents described in this specification may be combined and implemented.

[0140] Furthermore, each embodiment is merely an example, and even if a "modulation method, error correction coding method (error correction code to be used, code length, coding rate, etc.), control information, etc." is exemplified, it is possible to implement the same configuration even if a different "modulation method, error correction coding method (error correction code to be used, code length, coding rate, etc.), control information, etc." is applied.

[0141] Regarding the modulation method, even if a modulation method other than the modulation methods described in this specification is used, it is possible to implement the embodiments and other contents described in this specification. For example, APSK (Amplitude Phase Shift Keying) (e.g., 16APSK, 64APSK, 128APSK, 256APSK, 1024APSK, 4096APSK, etc.), PAM (Pulse Amplitude Modulation) (e.g., 4PAM, 8PAM, 16PAM, 64PAM, 128PAM, 256PAM, 1024PAM, 4096PAM, etc.), PSK (Phase Shift Keying) (e.g., BPSK, QPSK, 8PSK, 16PSK, 64PSK, 128PSK, 256PSK, 1024PSK, 4096PSK, etc.), QAM (Quadrature Amplitude Modulation) (e.g., 4QAM, 8QAM, 16QAM, 64QAM, 128QAM, Modulation schemes such as 256QAM, 1024QAM, and 4096QAM may be applied, and uniform mapping or non-uniform mapping may be used for each modulation scheme. Furthermore, the method of arranging 2, 4, 8, 16, 64, 128, 256, 1024, etc. signal points on the IQ plane (modulation schemes having 2, 4, 8, 16, 64, 128, 256, 1024, etc. signal points) is not limited to the signal point arrangement method of the modulation scheme shown in this specification.

[0142] The wireless device described in this specification may be, for example, communication and broadcasting equipment such as a broadcast station, base station, access point, terminal, mobile phone, etc., or communication equipment such as a television, radio, terminal, personal computer, mobile phone, access point, base station, etc. The wireless device described in this specification may also be a device having a communication function, and may be configured to be connectable via some kind of interface to a device for executing an application, such as a television, radio, personal computer, or mobile phone.

[0143] In addition, the receiving unit described in this specification may be equipped in, for example, communication and broadcasting equipment such as broadcasting stations, base stations, access points, terminals, and mobile phones, as well as communication equipment such as televisions, radios, terminals, personal computers, mobile phones, access points, and base stations.

[0144] In radio communication using radio waves in this embodiment, symbols other than data symbols, such as pilot symbols (preambles, unique words, postambles, reference symbols, etc.), control information symbols, etc. may be arranged in any manner in a frame. Here, they are called pilot symbols and control information symbols, but any naming method may be used; what is important is the function itself.

[0145] The pilot symbol may be, for example, a known symbol modulated by PSK modulation in the transmitter / receiver (or the receiver may be able to know the symbol transmitted by the transmitter by synchronizing with the symbol), and the receiver uses this symbol to perform frequency synchronization, time synchronization, channel estimation (for each modulated signal) (CSI (Channel State Information) estimation), signal detection, etc.

[0146] In addition, control information symbols are used to transmit information that needs to be transmitted to the other party in order to realize communication other than data (such as applications) (for example, the modulation method, error correction coding method, coding rate of the error correction coding method used in the communication, setting information in the upper layer, etc.).

[0147] The present invention is not limited to the embodiments, and can be implemented with various modifications. For example, in the embodiments, the case where the communication method is performed as a communication device is described, but the present invention is not limited to this, and the communication method can also be implemented as software.

[0148] For example, a program for executing the above communication method may be stored in advance in a ROM (Read Only Memory). Alternatively, the program may be stored in a memory (memory) and run by a CPU (Central Processor Unit).

[0149] In addition, a program for executing the above-mentioned communication method may be stored in a computer-readable storage medium, and the program stored in the storage medium may be recorded in the RAM (Random Access Memory) of the computer, causing the computer to operate in accordance with the program.

[0150] Furthermore, each configuration of the above-described embodiments may be realized as an LSI (Large Scale Integration), typically an integrated circuit. These may be individually integrated into a single chip, or a single chip may contain all or part of the configuration of each embodiment. While the term "LSI" is used here, it may also be referred to as an IC (Integrated Circuit), system LSI, super LSI, or ultra LSI depending on the level of integration. Furthermore, the integrated circuit implementation is not limited to LSI; it may also be implemented using a dedicated circuit or a general-purpose processor. It may also be implemented using a field programmable gate array (FPGA), which can be programmed after LSI fabrication, or a reconfigurable processor, which allows the connections and settings of circuit cells within an LSI to be reconfigured. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or a derivative technology, that technology may naturally be used to integrate functional blocks. The application of biotechnology, etc., is also a possibility.

[0151] (Fourth embodiment) FIG. 10 is a diagram illustrating an example of the configuration of a communication system according to the present embodiment. The communication system of FIG. 10 includes a device 1000 equipped with a visible light source such as an LED, an illumination source, or a light, a terminal 1050, and a base station 470, for example, that communicates with the terminal 1050. The device 1000 of FIG. 10 is equipped with a visible light source such as an LED, an illumination source, or a light. This device 1000 is referred to as a "second device" in this embodiment. In the second device 1000 of FIG. 10, components that operate in the same manner as the first device 100 of FIG. 1 are assigned the same numbers.

[0152] In the terminal 1050 of FIG. 10, components that operate in the same manner as the terminal 150 of FIG. 1 are assigned the same numbers.

[0153] It is assumed that communication between the wireless device 453 and the base station 470 in FIG. 10 uses, for example, radio waves.

[0154] 10, transmitter 101 receives information 1001-1 related to the SSID, information 1001-2 related to the encryption key, and data 1002 as input, generates an (optical) modulated signal based on these input signals, and outputs modulated signal 103. Modulated signal 103 is then transmitted from light source 104, for example.

[0155] Next, the information 1001-1 relating to the SSID and the information 1001-2 relating to the encryption key will be described.

[0156] First, the information 1001-1 relating to the SSID will be explained.

[0157] The SSID information 1001-1 is information indicating the SSID of the base station (or AP) 470 in FIG. 10. Note that, as an example, the base station (or AP) 470 transmits a modulated signal by radio waves and receives the modulated signal by radio waves. That is, the second device 1000 can provide the terminal with access to the base station 470, which is a secure access destination. This provides an effect that the terminal 1050 in FIG. 10 can securely obtain information from the base station (or AP) 470. On the other hand, the device 1000 can limit the terminals that access the base station 470 to terminals in a space that can receive an optical signal transmitted (irradiated) by the device 1000. Note that, when the terminal 1050 receives an optical signal transmitted in a predetermined manner, the terminal 1050 may determine that the notified SSID is the SSID of a secure base station, or may perform a process to determine whether it is secure. For example, the device 1000 may transmit an optical signal containing a predetermined identifier, and the terminal may determine whether the notified SSID is the SSID of a secure base station based on the received identifier.

[0158] Although only base station (or AP) 470 is shown in FIG. 10, even if there is a base station (or AP) other than base station (or AP) 470, terminal 1050 in FIG. 10 will access base station (or AP) 470 and obtain information.

[0159] Information 1001-2 regarding the encryption key is information regarding the encryption key that is required for terminal 1050 in Figure 10 to communicate with base station (or AP) 470 in Figure 10, and by obtaining this information from second device 1000 in Figure 10, terminal 1050 in Figure 10 is able to perform encrypted communication with base station (or AP) 470.

[0160] Terminal 1050 in Fig. 10 receives the modulated signal transmitted by second device 1000. Note that in terminal 1050 in Fig. 10, components that operate in the same manner as terminal 150 in Fig. 1 and terminal 450 in Fig. 4 are assigned the same numbers.

[0161] The light receiving unit 151, such as an image sensor such as a CMOS or organic CMOS, included in the terminal 1050 receives the modulated signal transmitted by the second device 1000. The receiving unit 153 receives the received signal 152 received by the light receiving unit 151 as input, performs processing such as demodulation and error correction decoding of the received signal, and outputs received data 154.

[0162] The data analyzer 155 receives the received data 154 as input and outputs, from the received data, for example, SSID information 1051 of the destination base station (470) and encryption key information 1052 for communicating with the destination base station (470). For example, in a wireless LAN (Local Area Network), encryption methods include WEP (Wired Equivalent Privacy), WPA (Wi-Fi Protected Access), and WPA2 (Wi-Fi Protected Access 2) (PSK (Pre-Shared Key) mode, EAP (Extended Authentication Protocol) mode). However, encryption methods are not limited to these.

[0163] Display unit 157 receives SSID information 1051 and encryption key information 1052 as input, and displays, for example, the SSID and encryption key of a communication partner accessed by wireless device 453 included in the terminal. (This display is referred to as the first display in this embodiment.)

[0164] For example, after the first display, wireless device 453 included in terminal 1050 in Fig. 10 receives SSID information 1051 and encryption key information 1052 as input, and establishes a connection with base station (or AP) 470 (for example, the connection is assumed to be made using radio waves). At this time, when base station (or AP) 470 communicates with wireless device 453 included in terminal 1050 in Fig. 10, it also transmits a modulated signal using, for example, radio waves.

[0165] Thereafter, wireless device 453 included in terminal 1050 in FIG. 10 receives data 1053 and control signal 1054 as input, modulates data 1053 under the control of control signal 1054, and transmits the modulated signal as radio waves.

[0166] Then, for example, base station (or AP) 470 transmits data to the network (471) and receives data from the network (472). After that, for example, base station (or AP) 470 transmits a modulated signal as a radio wave to terminal 1050 in FIG. 10.

[0167] 10 performs processes such as demodulation and error correction decoding on the modulated signal received as radio waves, and acquires received data 1056. Display unit 157 performs display based on received data 1056.

[0168] Fig. 11 shows an example of the frame structure of a modulated signal transmitted by second device 1000 of Fig. 10. In Fig. 11, the horizontal axis represents time, and the same symbols as those in Fig. 2 and Fig. 6 are assigned the same numbers, and their explanation will be omitted.

[0169] The symbol 600-1 relating to the SSID is a symbol for transmitting information 1001-1 relating to the SSID in Fig. 10, and the symbol 1101 relating to the encryption key is a symbol for transmitting information 1001-2 relating to the encryption key in Fig. 10. The data symbol 1102 is a symbol for transmitting the data 1002.

[0170] The second device transmits a preamble 201, a control information symbol 202, a symbol 600-1 related to the SSID, a symbol 1101 related to the encryption key, and a data symbol 1102. Note that the second device 1000 in Fig. 10 may transmit a frame including symbols other than those shown in Fig. 11. Furthermore, the frame configuration, including the order in which the symbols are transmitted, is not limited to that in Fig. 11.

[0171] Figure 12 shows an example of a frame structure of a modulated signal transmitted by radio equipment 453 included in terminal 1050 in Figure 10. In Figure 12, the horizontal axis represents time. As shown in Figure 12, radio equipment 453 included in terminal 1050 in Figure 10 transmits, for example, preamble 1201, and then transmits control information symbol 1202 and information symbol 1203.

[0172] In this case, the preamble 1201 is a symbol used by the base station (or AP) 470 that receives the modulated signal transmitted by the wireless device 453 of the terminal 1050 in FIG. 10 to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, frequency offset estimation, etc.

[0173] The control information symbol 1202 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the base station (or AP) 470 will perform demodulation of the modulated signal based on the information contained in this control information symbol 1202.

[0174] Information symbol 1203 is a symbol for transmitting data by radio equipment 453 of terminal 1050 in FIG.

[0175] Note that radio device 453 of terminal 1050 in FIG. 10 may transmit a frame including symbols other than those shown in FIG. 12 (for example, a frame including a pilot symbol (reference symbol) in the middle of information symbols). Also, the frame configuration, including the order in which symbols are transmitted, is not limited to that in FIG. 12. In FIG. 12, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0176] In the third embodiment, when radio equipment 453 included in terminal 1050 in FIG. 4 transmits a modulated signal, the frame configuration in FIG. 12 may be used.

[0177] Fig. 7 shows an example of a frame configuration of a modulated signal transmitted by base station 470 in Fig. 10. In Fig. 7, the horizontal axis represents time. As shown in Fig. 7, base station 470 transmits, for example, a preamble 701, followed by a control information symbol 702 and an information symbol 703.

[0178] In this case, the preamble 701 is a symbol used by the radio device 453 of the terminal 1050 in Figure 10, which receives the modulated signal transmitted by the base station 470, to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, frequency offset estimation, etc.

[0179] The control information symbol 702 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the radio device 453 of the terminal 1050 in Figure 10 will perform demodulation of the modulated signal based on the information in this symbol.

[0180] Information symbols 703 are symbols used by the base station (or AP) 470 in FIG. 10 to transmit data.

[0181] Note that the base station (or AP) 470 in FIG. 10 may transmit a frame including symbols other than those shown in FIG. 7 (for example, a frame including a pilot symbol (reference symbol) in the middle of an information symbol). Also, the frame configuration, including the order in which the symbols are transmitted, is not limited to that in FIG. 7. In addition, in FIG. 7, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0182] 11 transmitted by the second device 1000 at regular intervals, for example, repeatedly, so that multiple terminals can perform the operations described above.

[0183] FIG. 13 is a flowchart showing an example of the processing performed by the "second device 1000," "terminal 1050," and "base station (or AP) 470" in FIG. 10 described above.

[0184] First, as shown in 1301 in FIG. 13, the second device 1000 in FIG. 10 transmits a modulated signal having the frame structure in FIG.

[0185] 13, the modulated signal transmitted by the second device 1000 in FIG. 10 is received, and the terminal 1050 in FIG. 10 acquires the SSID of the base station that the terminal 1050 accesses.

[0186] 13, the terminal 1050 in FIG. 10 acquires an encryption key to be used for communication with the base station 470 that the terminal accesses.

[0187] Then, the terminal 1050 in FIG. 10 establishes a connection with the base station 470 in FIG. 10 via radio waves (1304).

[0188] 10, the terminal 1050 in FIG. 10 completes the connection with the base station 470 in FIG. 10, as shown in 1305 in FIG.

[0189] 13, terminal 1050 in FIG. 10 transmits connection destination information to base station 470 in FIG. 10 using radio waves.

[0190] 13, the base station 470 in FIG. 10 obtains information to be transmitted to the terminal 1050 in FIG. 10 from the network.

[0191] 13, the base station 470 in FIG. 10 transmits the acquired information to the terminal 1050 in FIG. 10 using radio waves, and the terminal 1050 in FIG. 10 receives the information.

[0192] Terminal 1050 in FIG. 10 obtains necessary information from the network via base station 470 in FIG. 10, for example, when necessary.

[0193] As described above, the terminal connects to the base station (or AP) based on the SSID information and encryption key information sent from the second device and obtains the information, thereby achieving the effect of being able to safely obtain information via a base station (or AP) whose security is guaranteed. This is because when information is obtained from a modulated signal of visible light, it is easy for the user to determine whether the source of the information is secure because it is visible light.

[0194] For example, if the SSID is obtained from the modulated signal of radio waves transmitted by a wireless LAN, it is difficult for the user to identify the device that transmitted the radio waves. Therefore, in terms of ensuring the security of information, it is more appropriate to obtain the SSID using visible light communication.

[0195] In this embodiment, the case where the second device transmits encryption key information is described. However, for example, if the base station (or AP) is not performing encrypted communication using an encryption key, the second device can be implemented in a similar manner by not transmitting encryption key information, but transmitting only information related to the SSID, and simply deleting the configuration related to the encryption key.

[0196] Furthermore, the configuration of the second device is not limited to the configuration shown in Figure 10, the configuration of the terminal is not limited to the configuration shown in Figure 10, and the connection destination and configuration method of the base station are not limited to those shown in Figure 10.

[0197] Although the present embodiment describes a case in which one base station (or AP) is installed in FIG. 10, there may be multiple (secure) base stations (or APs) accessible to the terminal (note that these base stations and the terminal transmit and receive modulated signals using radio waves). In this case, the symbol related to the SSID transmitted by the second device 1000 in FIG. 10 may include information on the SSID of each of the multiple base stations (or APs). Furthermore, the symbol related to the encryption key transmitted by the second device 1000 in FIG. 10 may include information on the encryption key used to connect to each of the multiple base stations (or APs). The terminal 1050 in FIG. 10 may select a base station (or AP) to connect to wirelessly (for example, via radio waves) based on the SSID information and encryption key information of the multiple base stations. (Or, it may connect to multiple base stations (or APs)).

[0198] For example, suppose there are three base stations (or APs). Let's name them base station #A, base station #B, and base station #C. Let's also say that the SSID of base station #A is "abcdef," the SSID of base station #B is "ghijk," and the SSID of base station #C is "pqrstu," and the encryption key for connecting to base station #A is "123," the encryption key for connecting to base station #B is "456," and the encryption key for connecting to base station #C is "789."

[0199] 11 of the modulated signal transmitted by the second device includes information on "the SSID of base station #A is 'abcdef'," "the SSID of base station #B is 'ghijk'," and "the SSID of base station #C is 'pqrstu'." Symbol 1101 related to the encryption key in the frame configuration of Fig. 11 includes information on "the encryption key for connecting with base station #A is '123'," "the encryption key for connecting with base station #B is '456'," and "the encryption key for connecting with base station #C is '789'."

[0200] 10 receives symbol 600-1 related to the SSID and obtains information such as "the SSID of base station #A is 'abcdef'," "the SSID of base station #B is 'ghijk'," and "the SSID of base station #C is 'pqrstu'," and receives symbol 1101 related to the encryption key and obtains information such as "the encryption key for connecting to base station #A is '123'," "the encryption key for connecting to base station #B is '456'," and "the encryption key for connecting to base station #C is '789'." Based on this information, terminal 1050 in FIG. 10 selects a base station (or AP) to connect to wirelessly (for example, via radio waves) and connects to it.

[0201] Furthermore, as in this embodiment, by using a light source, such as an LED, to set the base station to be accessed by the terminal, the modulated signal for radio transmitted by the terminal does not require a special setting mode for carrying out the procedure for connecting the terminal and the base station for wireless communication, and the modulated signal transmitted by the base station does not require a special setting mode for carrying out the procedure for connecting the terminal and the base station for wireless communication, thereby achieving the effect of improving the data transmission efficiency of wireless communication.

[0202] As explained earlier, the encryption key may be an encryption key for the SSID of a wireless LAN, or may be an encryption key for restricting the connection type, service type, network connection range, etc. (In other words, an encryption key may be introduced for some kind of restriction.)

[0203] (Embodiment 5) Here, we will explain the separation of SSID and password.

[0204] FIG. 14 shows an example of the configuration of a device equipped with a light source of visible light such as an LED, an illumination device, a light source, or a light, a terminal, and a base station, for example, that communicates with the terminal, in this embodiment. The communication system of FIG. 14 includes devices 1400A and 1400B equipped with a light source of visible light such as an LED, an illumination device, a light source, or a light, a terminal 1050, and a base station 470, for example, that communicates with terminal 1050. Device 1400A in FIG. 14 is referred to as a "third device" in this embodiment, and device 1400B in FIG. 14 is referred to as a "fourth device" in this embodiment. In terminal 1050 in FIG. 14, components that operate in the same manner as in FIGS. 1 and 10 are assigned the same numbers, and base stations or APs that operate in the same manner as in FIG. 4 are assigned the same numbers as in FIG. 4.

[0205] It is assumed that communication between wireless device 453 and base station 470 in FIG. 14 uses, for example, radio waves.

[0206] 14, transmitter 1404-1 receives SSID-related information 1401-1 and data 1402-1 as input, generates an (optical) modulated signal based on these input signals, and outputs modulated signal 1405-1. Modulated signal 1405-1 is then transmitted from light source 1406-1.

[0207] 14, a transmitter 1404-2 receives information 1403-2 related to the encryption key and data 1402-2 as input, generates an (optical) modulated signal based on these input signals, and outputs modulated signal 1405-2. Modulated signal 1405-2 is then transmitted from a light source 1406-2.

[0208] Next, the information 1401-1 relating to the SSID and the information 1403-2 relating to the encryption key will be described.

[0209] First, the information 1401-1 regarding the SSID will be explained.

[0210] Information 1401-1 related to SSID is information indicating the SSID of base station (or AP) 470 in Fig. 14. That is, third device 1400A can provide the terminal with access to base station 470, which is a secure access destination via radio waves. This provides the effect that terminal 1050 in Fig. 14 can securely obtain information from base station (or AP) 470.

[0211] When terminal 450 receives an optical signal transmitted in a predetermined manner, terminal 450 may determine that the notified SSID is the SSID of a safe base station, or may perform processing to determine whether the SSID is safe. For example, device 1400A may transmit an optical signal including a predetermined identifier, and terminal 450 may determine whether the notified SSID is the SSID of a safe base station based on the received identifier.

[0212] Although only base station (or AP) 470 is shown in FIG. 14, even if there is a base station (or AP) other than base station (or AP) 470, terminal 1050 in FIG. 14 will access base station (or AP) 470 and obtain information.

[0213] Information 1403-2 regarding the encryption key is information regarding the encryption key that is required for terminal 1050 in Figure 14 to communicate via radio waves with base station (or AP) 470 in Figure 14, and by obtaining this information from fourth device 1400B in Figure 14, terminal 1050 in Figure 14 is able to perform encrypted communication with base station (or AP) 470.

[0214] First, terminal 1050 in FIG. 14 receives the modulated signal transmitted by third device 1400A.

[0215] The terminal 1050 has a light receiving unit 151, such as an image sensor including a CMOS or an organic CMOS, which receives the modulated signal transmitted by the third device 1400A. The receiving unit 153 receives a received signal 152 received by the light receiving unit 151, performs processing such as demodulation and error correction decoding of the received signal, and outputs received data 154.

[0216] The data analyzer 155 receives the received data 154 and outputs, for example, information 1051 about the SSID of the base station (470) to be connected to from the received data.

[0217] Therefore, the wireless device 453 included in the terminal 1050 obtains, from the SSID information 1051, information on the SSID of the base station to which the wireless device 453 connects via radio waves.

[0218] Next, terminal 1050 in FIG. 14 receives the modulated signal transmitted by fourth device 1400B.

[0219] The terminal 1050 has a light receiving unit 151, such as an image sensor including a CMOS or an organic CMOS, which receives the modulated signal transmitted by the fourth device 1400B. The receiving unit 153 receives a received signal 152 received by the light receiving unit 151 as input, performs processing such as demodulation and error correction decoding of the received signal, and outputs received data 154.

[0220] The data analyzer 155 receives the received data 154 and outputs, for example, encryption key information 1052 for communicating with the destination base station (470) from the received data. For example, encryption methods for a wireless LAN (Local Area Network) include WEP (Wired Equivalent Privacy), WPA (Wi-Fi Protected Access), and WPA2 (Wi-Fi Protected Access 2) (PSK (Pre-Shared Key) mode and EAP (Extended Authentication Protocol) mode). However, encryption methods are not limited to these.

[0221] Therefore, the wireless device 453 provided in the terminal 1050 obtains the encryption key information of the base station to which the wireless device 453 is connected from the encryption key information 1052 for communicating with the base station (470) to which the wireless device 453 is connected (for example, via radio waves).

[0222] Display unit 157 receives SSID information 1051 and encryption key information 1052 as input, and displays, for example, the SSID and encryption key of a communication partner accessed by wireless device 453 included in the terminal. (This display is referred to as the first display in this embodiment.)

[0223] For example, after the first display, wireless device 453 included in terminal 1050 in Fig. 14 receives SSID information 1051 and encryption key information 1052 as input, and establishes a connection via radio waves with base station (or AP) 470 (for example, the connection is assumed to be made using radio waves). At this time, when base station (or AP) 470 communicates with wireless device 453 included in terminal 1050 in Fig. 14, it also transmits a modulated signal using, for example, radio waves.

[0224] Thereafter, wireless device 453 included in terminal 1050 in FIG. 14 receives data 1053 and control signal 1054 as input, modulates data 153 under the control of control signal 154, and transmits the modulated signal by radio waves.

[0225] Then, for example, base station (or AP) 470 transmits data to the network (471) and receives data from the network (472). After that, for example, base station (or AP) 470 transmits a modulated signal via radio waves to terminal 1050 in FIG. 14.

[0226] 14 performs processes such as demodulation and error correction decoding on the received modulated signal to obtain received data 1056. Display unit 157 performs display based on received data 1056.

[0227] Fig. 15 shows an example of a frame configuration of a modulated signal transmitted by the third device 1400A of Fig. 14. In Fig. 15, the horizontal axis represents time, and the same symbols as those in Fig. 2, Fig. 6, and Fig. 11 are assigned the same reference numerals, and their explanations will be omitted.

[0228] The symbol 600-1 relating to the SSID is a symbol for transmitting information 1401-1 relating to the SSID in Fig. 14. The data symbol 1102 is a symbol for transmitting data 1402-1.

[0229] The third device transmits a preamble 201, a control information symbol 202, a symbol 600-1 related to the SSID, and a data symbol 1102. Note that the third device 1400A in Fig. 14 may transmit a frame including symbols other than those shown in Fig. 15. Furthermore, the frame configuration, including the order in which the symbols are transmitted, is not limited to the configuration in Fig. 15.

[0230] Fig. 16 shows an example of the frame structure of a modulated signal transmitted by fourth device 1400B in Fig. 14. In Fig. 16, the horizontal axis represents time, and the same symbols as in Fig. 2 and Fig. 11 are assigned the same reference numerals, and their explanations will be omitted.

[0231] The symbol 1101 relating to the encryption key is a symbol for transmitting information 1403-2 relating to the encryption key in Fig. 14. The data symbol 1102 is a symbol for transmitting data 1402-2.

[0232] The fourth device transmits a preamble 201, a control information symbol 202, a symbol 1101 related to an encryption key, and a data symbol 1102. Note that the fourth device 1400B in Fig. 14 may transmit a frame including symbols other than those shown in Fig. 16. Furthermore, the frame configuration, including the order in which the symbols are transmitted, is not limited to that shown in Fig. 16.

[0233] Fig. 12 shows an example of a frame structure of a modulated signal transmitted by radio equipment 453 included in terminal 1050 in Fig. 14. In Fig. 12, the horizontal axis represents time. As shown in Fig. 12, radio equipment 453 included in terminal 1050 in Fig. 14 transmits, for example, preamble 1201, and then transmits control information symbol 1202 and information symbol 1203.

[0234] In this case, the preamble 1201 is a symbol used by the base station (or AP) 470 that receives the modulated signal transmitted by the wireless device 453 of the terminal 1050 in FIG. 14 to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, frequency offset estimation, etc.

[0235] The control information symbol 1202 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the base station (or AP) 470 will perform demodulation of the modulated signal based on the information contained in this control information symbol 1202.

[0236] Information symbol 1203 is a symbol for transmitting data by radio equipment 453 of terminal 1050 in FIG.

[0237] Note that radio device 453 of terminal 1050 in FIG. 14 may transmit a frame including symbols other than those shown in FIG. 12 (for example, a frame including a pilot symbol (reference symbol) in the middle of information symbols). Also, the frame configuration, including the order in which symbols are transmitted, is not limited to that in FIG. 12. In FIG. 12, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0238] Fig. 7 shows an example of a frame configuration of a modulated signal transmitted by base station 470 in Fig. 14. In Fig. 7, the horizontal axis represents time. As shown in Fig. 7, base station 470 transmits, for example, a preamble 701, followed by a control information symbol 702 and an information symbol 703.

[0239] In this case, the preamble 701 is a symbol used by the radio device 453 of the terminal 1050 in Figure 10, which receives the modulated signal transmitted by the base station 470, to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, frequency offset estimation, etc.

[0240] The control information symbol 702 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the radio device 453 of the terminal 1050 in Figure 14 will perform demodulation of the modulated signal based on the information in this symbol.

[0241] Information symbols 703 are symbols used by the base station (or AP) 470 in FIG. 14 to transmit data.

[0242] Note that the base station (or AP) 470 in FIG. 14 may transmit a frame including symbols other than those shown in FIG. 7 (for example, a frame including a pilot symbol (reference symbol) in the middle of an information symbol). Also, the frame configuration, including the order in which the symbols are transmitted, is not limited to that in FIG. 7. In addition, in FIG. 7, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0243] 15 transmitted by the third device 1400A at regular intervals, for example, repeatedly, so that multiple terminals can perform the operations described above.

[0244] Similarly, the modulated signal having the frame structure shown in Fig. 16 transmitted by the fourth device 1400B may be transmitted at regular intervals, for example, repeatedly, thereby enabling multiple terminals to perform the operations described above.

[0245] Fig. 17 is a flowchart showing a first example of the processing performed by the "third device 1400A," "fourth device 1400B," "terminal 1050," and "base station (or AP) 470" in Fig. 14. In Fig. 17, the same numbers are used for components that operate in the same way as in Fig. 13.

[0246] First, as shown in 1701 in FIG. 17, the third device 1400A in FIG. 14 transmits a modulated signal having the frame structure in FIG.

[0247] 17, the modulated signal transmitted by the third device 1400A in FIG. 14 is received, and the terminal 1050 in FIG. 14 acquires the SSID of the base station that the terminal 1050 accesses.

[0248] Next, as shown in 1703 in FIG. 17, the fourth device 1400B in FIG. 14 transmits a modulated signal having the frame structure shown in FIG.

[0249] Then, as shown in 1704 of FIG. 17, the modulated signal transmitted by the fourth device 1400B of FIG. 14 is received, and the terminal 1050 of FIG. 14 acquires the encryption key to be used for communication with the base station 470 to which the terminal is accessing.

[0250] Then, the terminal 1050 in FIG. 14 establishes a connection with the base station 470 in FIG. 14 via radio waves (1304).

[0251] 14, the terminal 1050 in FIG. 14 completes connection with the base station 470 in FIG. 14 by radio waves, as shown in 1305 in FIG.

[0252] 17, the terminal 1050 in FIG. 14 transmits connection destination information to the base station 470 in FIG. 14 using radio waves.

[0253] 17, the base station 470 in FIG. 14 obtains information to be transmitted to the terminal 1050 in FIG. 14 from the network.

[0254] Then, as in 1308 in FIG. 17, base station 470 in FIG. 14 transmits the obtained information to terminal 1050 in FIG. 14 using radio waves, and terminal 1050 in FIG. 14 receives the information.

[0255] Terminal 1050 in FIG. 14 obtains necessary information from the network via base station 470 in FIG. 14, for example, when necessary.

[0256] Fig. 18 is a flowchart showing a second example of the processing performed by the "third device 1400A," "fourth device 1400B," "terminal 1050," and "base station (or AP) 470" in Fig. 14. In Fig. 18, the same numbers are used for components that operate in the same way as in Fig. 13.

[0257] First, as shown in 1801 in FIG. 18, the fourth device 1400B in FIG. 14 transmits a modulated signal having the frame structure in FIG.

[0258] Then, as shown in 1802 in FIG. 18, the modulated signal transmitted by the fourth device 1400B in FIG. 14 is received, and the terminal 1050 in FIG. 14 acquires the encryption key to be used for communication with the base station that the terminal 1050 accesses.

[0259] Next, as shown in 1803 in FIG. 18, the third device 1400A in FIG. 14 transmits a modulated signal having the frame structure shown in FIG.

[0260] Then, as in 1804 in FIG. 18, the modulated signal transmitted by the third device 1400A in FIG. 14 is received, and the terminal 1050 in FIG. 14 acquires the SSID of the base station 470 that the terminal accesses.

[0261] Then, the terminal 1050 in FIG. 14 establishes a connection with the base station 470 in FIG. 14 via radio waves (1304).

[0262] 14, the terminal 1050 in FIG. 14 completes connection with the base station 470 in FIG. 14 by radio waves, as shown in 1305 in FIG.

[0263] 18, terminal 1050 in FIG. 14 transmits connection destination information to base station 470 in FIG. 14 using radio waves.

[0264] 18, the base station 470 in FIG. 14 obtains information to be transmitted to the terminal 1050 in FIG. 14 from the network.

[0265] Then, as in 1308 in FIG. 18, base station 470 in FIG. 14 transmits the obtained information to terminal 1050 in FIG. 14 using radio waves, and terminal 1050 in FIG. 14 receives the information.

[0266] Terminal 1050 in FIG. 14 obtains necessary information from the network via base station 470 in FIG. 14, for example, when necessary.

[0267] As described above, the terminal can connect to a base station (or AP) based on the SSID information and encryption key information sent from the third and fourth devices and obtain the information, thereby achieving the effect of being able to safely obtain information via a base station (or AP) whose security is guaranteed. This is because when information is obtained from a modulated signal of visible light, it is easy for the user to determine whether the source of the information is secure because it is visible light.

[0268] For example, if the SSID is obtained from the modulated signal of radio waves transmitted by a wireless LAN, it is difficult for the user to identify the device that transmitted the radio waves. Therefore, in terms of ensuring the security of information, it is more appropriate to obtain the SSID using visible light communication.

[0269] In this embodiment, the fourth device transmits encryption key information. However, if the base station (or AP) is not performing encrypted communication using an encryption key, the fourth device can be implemented in the same manner by transmitting only information related to the SSID without transmitting encryption key information, and by simply deleting the configuration related to the encryption key.

[0270] Furthermore, as in this embodiment, by separating the device that transmits information about the SSID from the device that transmits information about the encryption key, the terminal can achieve more secure communication with the base station.

[0271] For example, consider the space shown in Figure 19. As shown in Figure 19, there are Area #1 and Area #2, and there is a doorway and a wall between Area #1 and Area #2. Furthermore, movement from Area #1 to Area #2 and from Area #2 to Area #1 can only be made through the doorway.

[0272] A base station (or AP) is installed in area #1 of Fig. 19, as well as a third device and a fourth device, while only the third device is installed in area #2.

[0273] It is assumed that radio waves transmitted by the base station (or AP) can be received in both area #1 and area #2. In this case, a terminal in area #1 where the fourth device is installed can communicate with the base station. Furthermore, if a terminal that has connected to the base station in area #1 moves to area #2, it can still communicate with the base station.

[0274] Then, if a terminal that has connected to a base station in area #1 moves to an area other than area #1 or area #2, and then returns to either area #1 or area #2, it will be able to communicate with the base station.

[0275] On the other hand, a terminal that cannot enter area #1 cannot obtain the encryption key. In this case, the terminal knows only the SSID of the base station (or AP). In this case, the terminal may be able to communicate with the base station using services that can be enjoyed by knowing only the SSID.

[0276] Therefore, only terminals that are able to enter area #1 can communicate with the base station, thereby ensuring the security of communications. It is also possible to build a system that can provide different services in different areas.

[0277] Furthermore, by changing the encryption key used by the terminal to communicate with the base station (for example, at certain time intervals), communication with the base station will no longer be possible using the encryption key before the change, and this type of operation will enable more secure communication.

[0278] As explained earlier, the encryption key may be an encryption key for the SSID of a wireless LAN, or may be an encryption key for restricting the connection type, service type, network connection range, etc. (In other words, an encryption key may be introduced for some kind of restriction.)

[0279] The configuration of the third device and the configuration of the fourth device are not limited to the configuration shown in FIG. 14, and the configuration of the terminal is not limited to the configuration shown in FIG. 14, and the connection destination and configuration method of the base station are not limited to those shown in FIG. 14.

[0280] Although the present embodiment describes a case in which one base station (or AP) is installed in FIG. 14, there may be a plurality of (secure) base stations (or APs) accessible to the terminal. In this case, the symbol relating to the SSID transmitted by third device 1400A in FIG. 14 may include information on the SSID of each of the plurality of base stations (or APs). Furthermore, the symbol relating to the encryption key transmitted by fourth device 1400B in FIG. 14 may include information on the encryption key used to connect to each of the plurality of base stations (or APs). Terminal 1050 in FIG. 14 may select a base station (or AP) to wirelessly connect to (or connect to a plurality of base stations (or APs)) based on the information on the SSID and encryption key of the plurality of base stations.

[0281] For example, suppose there are three base stations (or APs). Let's name them base station #A, base station #B, and base station #C. Let's also say that the SSID of base station #A is "abcdef," the SSID of base station #B is "ghijk," and the SSID of base station #C is "pqrstu," and the encryption key for connecting to base station #A is "123," the encryption key for connecting to base station #B is "456," and the encryption key for connecting to base station #C is "789."

[0282] 15 of the modulated signal transmitted by the third device includes information on "the SSID of base station #A is 'abcdef'," "the SSID of base station #B is 'ghijk'," and "the SSID of base station #C is 'pqrstu'." Furthermore, symbol 1101 of the encryption key of the modulated signal transmitted by the fourth device includes information on "the encryption key for connecting with base station #A is '123'," "the encryption key for connecting with base station #B is '456'," and "the encryption key for connecting with base station #C is '789'."

[0283] 14 receives symbol 600-1 related to the SSID and obtains information such as "the SSID of base station #A is 'abcdef'," "the SSID of base station #B is 'ghijk'," and "the SSID of base station #C is 'pqrstu'," and receives symbol 1101 related to the encryption key and obtains information such as "the encryption key for connecting to base station #A is '123'," "the encryption key for connecting to base station #B is '456'," and "the encryption key for connecting to base station #C is '789'." Then, based on this information, terminal 1050 in FIG. 14 selects a base station (or AP) to connect to wirelessly and establishes a connection.

[0284] Furthermore, as in this embodiment, by using a light source, such as an LED, to set the base station to be accessed by the terminal, the modulated signal for radio transmitted by the terminal does not require a special setting mode for carrying out the procedure for connecting the terminal and the base station for wireless communication, and the modulated signal transmitted by the base station does not require a special setting mode for carrying out the procedure for connecting the terminal and the base station for wireless communication, thereby achieving the effect of improving the data transmission efficiency of wireless communication.

[0285] (Sixth embodiment) Here, an example will be described in which a base station and an LED are mounted on the base station.

[0286] Fig. 20 is a diagram showing an example of the configuration of a communication system according to this embodiment. The communication system in Fig. 20 includes a visible light source such as an LED, an illumination, a light source, and a light, and further includes base station 2000 and terminal 1050 each equipped with wireless device 2001. In Fig. 20, components that operate in the same way as in Figs. 1 and 10 are assigned the same numbers.

[0287] It is assumed that the communication between the wireless device 2001 and the wireless device 453 in FIG. 20 uses, for example, radio waves.

[0288] 20 includes, for example, a visible light, illumination, light source, or light such as an LED. First, the operation of the parts related to the visible light, illumination, light source, or light such as an LED will be described.

[0289] Transmitting unit 101 receives as input information 1001-1 related to the SSID, information 1001-2 related to the encryption key, and data 1002, generates an (optical) modulated signal based on these input signals, and outputs modulated signal 103. Modulated signal 103 is then transmitted from light source 104, for example.

[0290] Next, the information 1001-1 relating to the SSID and the information 1001-2 relating to the encryption key will be described.

[0291] First, the information 1001-1 relating to the SSID will be explained.

[0292] The SSID information 1001-1 is information indicating the SSID of, for example, wireless device 2001 using radio waves of base station (or AP) 2000 in Fig. 20. In other words, "parts related to visible light such as LED, illumination, light source, and light" can provide a terminal with secure wireless access to wireless device 2001, which is the access destination. This provides the effect that terminal 1050 in Fig. 20 can securely obtain information from wireless device 2001.

[0293] On the other hand, a portion of base station 200 related to visible light, illumination, light source, or light such as an LED can limit terminals that access wireless device 2001 to terminals in a space that can receive an optical signal transmitted (irradiated) by a portion of base station 200 related to visible light, illumination, light source, or light such as an LED. When terminal 1050 receives an optical signal transmitted in a predetermined manner, it may determine that the notified SSID is the SSID of a safe base station, or may perform processing to determine whether or not the SSID is safe. For example, a portion of base station 200 related to visible light, illumination, light source, or light such as an LED may transmit an optical signal including a predetermined identifier, and the terminal may determine whether or not the notified SSID is the SSID of a safe base station based on the received identifier.

[0294] Although only base station (or AP) 2000 is shown in FIG. 20, even if there are base stations (or APs) other than base station (or AP) 2000, terminal 1050 in FIG. 20 will access base station (or AP) 2000 and obtain information.

[0295] Information 1001-2 relating to the encryption key is information relating to the encryption key that is required for terminal 1050 in Fig. 20 to communicate with wireless device 2001 in Fig. 20, and terminal 1050 in Fig. 20 can perform encrypted communication with wireless device 2001 by obtaining this information from a part related to visible light such as an LED, illumination, light source, or light. Terminal 1050 in Fig. 20 receives a modulated signal transmitted by a part related to visible light such as an LED, illumination, light source, or light in base station 200.

[0296] 20, components that operate in the same manner as the terminal 150 in FIG. 1 and the terminal 1050 in FIG. 10 are assigned the same numbers.

[0297] A light receiving unit 151 such as an image sensor, for example, a CMOS or an organic CMOS, provided in the terminal 1050 receives a modulated signal transmitted from a part related to visible light, illumination, a light source, or a light, such as an LED, in the base station 200. Then, a receiving unit 153 receives a received signal 152 received by the light receiving unit 151 as input, performs processing such as demodulation and error correction decoding of the received signal, and outputs received data 154.

[0298] Data analysis unit 155 receives received data 154 as input and outputs, from the received data, for example, SSID information 1051 of wireless device 2001 of the destination base station and encryption key information 1052 for communicating with wireless device 2001 of the destination base station. For example, in a wireless LAN (Local Area Network), encryption methods include WEP (Wired Equivalent Privacy), WPA (Wi-Fi Protected Access), and WPA2 (Wi-Fi Protected Access 2) (PSK (Pre-Shared Key) mode, EAP (Extended Authentication Protocol) mode). However, encryption methods are not limited to these.

[0299] Display unit 157 receives SSID information 1051 and encryption key information 1052 as input, and displays, for example, the SSID and encryption key of a communication partner accessed by wireless device 453 included in the terminal. (This display is referred to as the first display in this embodiment.)

[0300] For example, after the first display, wireless device 453 included in terminal 1050 in Fig. 20 receives SSID information 1051 and encryption key information 1052 as input, and establishes a connection with wireless device 2001 of base station (or AP) 2000 (for example, the connection is assumed to be made using radio waves). At this time, when wireless device 2001 of base station (or AP) 2000 communicates with wireless device 453 included in terminal 1050 in Fig. 20, it also transmits a modulated signal using, for example, radio waves.

[0301] Thereafter, wireless device 453 included in terminal 1050 in FIG. 20 receives data 1053 and control signal 1054 as input, modulates data 1053 under the control of control signal 154, and transmits the modulated signal as radio waves. Then, for example, wireless device 2001 of base station (or AP) 2000 transmits data to the network (471) and receives data from the network (472). Thereafter, for example, wireless device 2001 of base station (or AP) 2000 transmits the modulated signal as radio waves to terminal 1050 in FIG. 20. Wireless device 453 included in terminal 1050 in FIG. 20 performs processes such as demodulation and error correction decoding on the modulated signal received as radio waves, and acquires received data 1056. Display unit 157 displays based on the received data 1056.

[0302] Fig. 11 shows an example of a frame configuration of a modulated signal transmitted by wireless device 2001 of base station (or AP) 2000 in Fig. 20. In Fig. 11, the horizontal axis represents time, and the same symbols as those in Fig. 2 and Fig. 6 are assigned the same numbers, and their explanation will be omitted.

[0303] The symbol 600-1 relating to the SSID is a symbol for transmitting information 1001-1 relating to the SSID in Fig. 20, and the symbol 1101 relating to the encryption key is a symbol for transmitting information 1001-2 relating to the encryption key in Fig. 20. The data symbol 1102 is a symbol for transmitting the data 1002.

[0304] Wireless device 2001 of base station (or AP) 2000 transmits preamble 201, control information symbol 202, SSID-related symbol 600-1, encryption key-related symbol 1101, and data symbol 1102. Note that wireless device 2001 of base station (or AP) 2000 in Fig. 20 may transmit a frame including symbols other than those shown in Fig. 11. Furthermore, the frame configuration, including the order in which the symbols are transmitted, is not limited to that in Fig. 11.

[0305] Fig. 12 shows an example of a frame structure of a modulated signal transmitted by radio equipment 453 included in terminal 1050 in Fig. 20. In Fig. 12, the horizontal axis represents time. As shown in Fig. 12, radio equipment 453 included in terminal 1050 in Fig. 20 transmits, for example, preamble 1201, and then transmits control information symbol 1202 and information symbol 1203.

[0306] In this case, the preamble 1201 is a symbol used by the wireless device 2001 of the base station (or AP) 2000 that receives the modulated signal transmitted by the wireless device 453 of the terminal 1050 in FIG. 20 to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, frequency offset estimation, etc.

[0307] The control information symbol 1202 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the wireless device 2001 of the base station (or AP) 2000 will perform demodulation of the modulated signal based on the information contained in this control information symbol 1202.

[0308] Information symbol 1203 is a symbol for transmitting data by radio equipment 453 of terminal 1050 in FIG.

[0309] Note that radio device 453 of terminal 1050 in FIG. 20 may transmit a frame including symbols other than those shown in FIG. 12 (for example, a frame including a pilot symbol (reference symbol) in the middle of information symbols). Also, the frame configuration, including the order in which symbols are transmitted, is not limited to that in FIG. 12. In FIG. 12, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0310] Fig. 7 shows an example of a frame structure of a modulated signal transmitted by wireless device 2001 in Fig. 20. The horizontal axis in Fig. 7 represents time. As shown in Fig. 7, base station 470 transmits, for example, a preamble 701, followed by a control information symbol 702 and an information symbol 703.

[0311] In this case, the preamble 701 is a symbol used by the radio device 453 of the terminal 1050 in Figure 2, which receives the modulated signal transmitted by the radio device 2001 in Figure 20, to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, frequency offset estimation, etc.

[0312] The control information symbol 702 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the radio device 453 of the terminal 1050 in Figure 20 will perform demodulation of the modulated signal based on the information in this symbol.

[0313] Information symbol 703 is a symbol for wireless device 2001 in FIG. 20 to transmit data.

[0314] Note that radio device 2001 of base station 2000 in FIG. 20 may transmit a frame including symbols other than those shown in FIG. 7 (for example, a frame including a pilot symbol (reference symbol) in the middle of information symbols). Also, the frame configuration, including the order in which symbols are transmitted, is not limited to that in FIG. 7. In FIG. 7, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0315] 11 transmitted by a part related to visible light, illumination, light source, or light, such as an LED in base station 200, can be transmitted at regular intervals, for example, repeatedly, thereby enabling multiple terminals to perform the operations described above.

[0316] FIG. 21 is a flowchart showing an example of the processing performed by the "portions related to visible light such as LEDs, illumination, light sources, and lights," "terminal 1050," and "wireless device 2001 of base station (or AP)" in FIG. 20 described above.

[0317] First, like 1301 in FIG. 13, the part related to visible light, illumination, light source, and light such as LED in FIG. 20 transmits a modulated signal with the frame configuration in FIG.

[0318] Then, as shown in 1302 in FIG. 13, the modulated signal transmitted by the part related to visible light, illumination, light source, or light such as the LED in FIG. 20 is received, and the terminal 1050 in FIG. 20 acquires the SSID of the base station that the terminal 1050 accesses.

[0319] 13, the terminal 1050 in FIG. 20 acquires an encryption key to be used for communication with the base station 470 that the terminal accesses.

[0320] Then, the terminal 1050 in FIG. 20 establishes a connection with the wireless device 2001 of the base station 2000 in FIG. 20 by radio waves (1304).

[0321] 20, terminal 1050 in FIG. 20 completes connection with wireless device 2001 in base station 2000 in FIG. 20, as shown in 1305 in FIG.

[0322] 13, terminal 1050 in FIG. 20 transmits connection destination information to wireless device 2001 of base station 2000 in FIG. 20 using radio waves.

[0323] 13, wireless device 2001 of base station 2000 in FIG. 20 obtains information to be transmitted to terminal 1050 in FIG. 20 from the network.

[0324] 13, wireless device 2001 of base station 2000 in FIG. 20 transmits the acquired information to terminal 1050 in FIG. 20 using radio waves, and terminal 1050 in FIG. 20 receives the information.

[0325] For example, terminal 1050 in FIG. 20 acquires necessary information from the network via wireless device 2001 of base station 2000 in FIG. 20 when necessary.

[0326] As described above, the terminal can connect to the wireless device of the base station (or AP) based on the SSID information and encryption key information transmitted from the parts related to visible light, illumination, light source, and light such as LEDs in the base station and obtain the information, thereby achieving the effect of being able to safely obtain information via a base station (or AP) whose security is guaranteed. This is because when information is obtained from a modulated signal of visible light, it is easy for the user to determine whether the source of the information is safe because it is visible light.

[0327] For example, if the SSID is obtained from the modulated signal of radio waves transmitted by a wireless LAN, it is difficult for the user to identify the device that transmitted the radio waves. Therefore, in terms of ensuring the security of information, it is more appropriate to obtain the SSID using visible light communication.

[0328] In this embodiment, a case is described in which parts of a base station related to visible light, illumination, light sources, and lights such as LEDs transmit encryption key information. However, if the wireless device of the base station (or AP) does not perform encrypted communication using an encryption key, the parts of the base station related to visible light, illumination, light sources, and lights such as LEDs do not transmit encryption key information, but transmit only information related to the SSID, and the configuration related to the encryption key can be similarly implemented by simply deleting the configuration.

[0329] 20, the SSID and encryption key of wireless device 2001 of base station 2000 may be rewritable. For example, in FIG. 20, wireless device 2001 receives information 1001-1 related to the SSID and information 1001-2 related to the encryption key. Wireless device 2001 of base station 2000 rewrites the SSID and encryption key based on the input information 1001-1 related to the SSID and information 1001-2 related to the encryption key. This further ensures the security of communications between the terminal and wireless device 2001 of base station 2000. (Note that although wireless device 2001 of base station 2000 has a function for rewriting the SSID and encryption key in FIG. 20, this function may not be included in the configuration.)

[0330] Furthermore, the configuration of the parts related to visible light, illumination, light sources, and lights such as LEDs in the base station is not limited to the configuration shown in Figure 20, and the configuration of the terminal is not limited to the configuration shown in Figure 20, and the connection destination and configuration method of the base station's radio equipment are not limited to those shown in Figure 20.

[0331] Although the present embodiment describes a case in which one base station (or AP) is installed in FIG. 20 , there may be multiple wireless devices of base stations (or APs) accessible to the terminal (secure). (Note that the wireless devices of these base stations and the terminal transmit and receive modulated signals using radio waves.) In this case, the symbols related to SSIDs transmitted by the components related to visible light, illumination, light sources, and lights, such as LEDs, in FIG. 20 may include information on the SSIDs of the wireless devices of these multiple base stations (or APs). Furthermore, the symbols related to encryption keys transmitted by the components related to visible light, illumination, light sources, and lights, such as LEDs, in FIG. 20 may include information on encryption keys used to connect to each of the wireless devices of these multiple base stations (or APs). Terminal 1050 in FIG. 20 may select a wireless device of a base station (or AP) to connect to wirelessly (for example, via radio waves) based on the SSID information and encryption key information of the wireless devices of the multiple base stations (or APs).

[0332] For example, suppose there are three base stations (or APs) equipped with wireless devices. These are named wireless device #A, wireless device #B, and wireless device #C. The SSID of wireless device #A is "abcdef," the SSID of wireless device #B is "ghijk," and the SSID of wireless device #C is "pqrstu." The encryption key for connecting to wireless device #A is "123," the encryption key for connecting to wireless device #B is "456," and the encryption key for connecting to wireless device #C is "789."

[0333] 11 of the modulated signal transmitted by the units related to visible light, illumination, light sources, and lights such as LEDs in base station 200 includes information related to "the SSID of wireless device #A is 'abcdef'," "the SSID of wireless device #B is 'ghijk'," and "the SSID of wireless device #C is 'pqrstu'." Symbol 1101 related to the encryption key in the frame configuration of Fig. 11 includes information related to "the encryption key for connecting with wireless device #A is '123'," "the encryption key for connecting with wireless device #B is '456'," and "the encryption key for connecting with wireless device #C is '789'."

[0334] 20 receives symbol 600-1 related to the SSID and obtains information such as "SSID of wireless device #A is 'abcdef'," "SSID of wireless device #B is 'ghijk'," and "SSID of wireless device #C is 'pqrstu'," and receives symbol 1101 related to the encryption key and obtains information such as "encryption key for connecting with wireless device #A is '123'," "encryption key for connecting with wireless device #B is '456'," and "encryption key for connecting with wireless device #C is '789'." Based on this information, terminal 1050 in FIG. 20 selects a base station (or AP) to connect to wirelessly (for example, via radio waves) and establishes a connection.

[0335] Furthermore, as in this embodiment, by using a light source, such as an LED, to configure the wireless device of the base station to be accessed by the terminal, the modulated signal for radio transmitted by the terminal does not require a special setting mode for carrying out the procedure for connecting the wireless communication between the terminal and the base station, and the modulated signal transmitted by the base station does not require a special setting mode for carrying out the procedure for connecting the wireless communication between the terminal and the base station, thereby achieving the effect of improving the data transmission efficiency of wireless communication.

[0336] As explained earlier, the encryption key may be an encryption key for the SSID of a wireless LAN, or may be an encryption key for restricting the connection type, service type, network connection range, etc. (In other words, an encryption key may be introduced for some kind of restriction.)

[0337] (Embodiment 7) Here, an example will be described in which there are a plurality of base stations and access control is performed.

[0338] Fig. 22 is a diagram showing an example of the configuration of a communication system according to this embodiment. The communication system in Fig. 22 includes, for example, a device 1000 equipped with a light source of visible light such as an LED, illumination, a light source, or a light, a terminal 1050, and base station #1 470-1, base station #2 470-2, and base station #3 470-3, for example, which communicate with terminal 1050. In Fig. 22, components that operate in the same manner as in Figs. 1, 4, and 10 are assigned the same numbers.

[0339] The device 1000 in Fig. 22 is equipped with visible light, illumination, a light source, or a light, such as an LED. This device 1000 is referred to as the "fifth device" in this embodiment. It is assumed that the communication between the wireless device 453 and base station #1 of 470-1, the communication between the wireless device 453 and base station #2 of 470-2, and the communication between the wireless device 453 and base station # of 470-3 in Fig. 22 uses, for example, radio waves.

[0340] 22, transmitter 101 receives information 1001-1 related to the SSID, information 1001-2 related to the encryption key, and data 1002 as input, generates an (optical) modulated signal based on these input signals, and outputs modulated signal 103. Modulated signal 103 is then transmitted from light source 104, for example.

[0341] Next, the information 1001-1 relating to the SSID and the information 1001-2 relating to the encryption key will be described.

[0342] First, the information 1001-1 relating to the SSID will be explained.

[0343] SSID information 1001-1 is, for example, information indicating the SSID of base station (or AP) 470-1 in FIG. 22, information indicating the SSID of base station (or AP) 470-2, and information indicating the SSID of base station (or AP) 470-3. Note that, as an example, base stations (or APs) 470-1, 470-2, and 470-3 transmit modulated signals by radio waves and receive modulated signals by radio waves. In other words, fifth device 1000 can provide the terminal with access to base stations 470-1, 470-2, and 470-3, which are secure access destinations. This provides the effect that terminal 1050 in FIG. 22 can securely obtain information from base stations (or APs) 470-1, 470-2, and 470-3.

[0344] On the other hand, device 1000 can limit terminals that access base stations 470-1, 470-2, and 470-3 to terminals in a space that can receive the optical signal transmitted (irradiated) by device 1000. When terminal 1050 receives an optical signal transmitted in a predetermined manner, it may determine that the notified SSID is the SSID of a safe base station, or may perform processing to determine whether or not it is safe. For example, device 1000 may transmit an optical signal including a predetermined identifier, and the terminal may determine whether or not the notified SSID is the SSID of a safe base station based on the received identifier.

[0345] Although FIG. 22 shows base stations (or APs) 470-1, 470-2, and 470-3, for example, base stations (or APs) other than base stations (or APs) 470-1, 470-2, and 470-3 may also exist.

[0346] Information 1001-2 regarding the encryption key is information regarding the encryption key that is required for terminal 1050 in Figure 22 to communicate with base stations (or APs) 470-1, 470-2, and 470-3 in Figure 22, and by obtaining this information from fifth device 1000 in Figure 22, terminal 1050 in Figure 22 becomes able to perform encrypted communication "between the terminal and base station (or AP) 470-1," "between the terminal and base station (or AP) 470-2," and "between the terminal and base station (or AP) 470-3."

[0347] Terminal 1050 in Fig. 22 receives a modulated signal transmitted by fifth device 1000. Note that in terminal 1050 in Fig. 22, components that operate in the same manner as terminal 150 in Fig. 1 and terminal 450 in Fig. 4 are assigned the same numbers.

[0348] Light receiving unit 151, such as an image sensor such as CMOS or organic CMOS, included in terminal 1050 receives the modulated signal transmitted by fifth device 1000. Then, receiving unit 153 receives received signal 152 received by light receiving unit 151 as input, performs processing such as demodulation and error correction decoding of the received signal, and outputs received data 154.

[0349] The data analyzer 155 receives the received data 154 as input, and outputs, from the received data, for example, SSID information 1051 of the destination base station (470-1, 470-2, 470-3) and encryption key information 1052 for communicating with the destination base station (470-1, 470-2, 470-3). For example, in a wireless LAN (Local Area Network), encryption methods include WEP (Wired Equivalent Privacy), WPA (Wi-Fi Protected Access), and WPA2 (Wi-Fi Protected Access 2) (PSK (Pre-Shared Key) mode, EAP (Extended Authentication Protocol) mode). However, the encryption method is not limited to these.

[0350] Display unit 157 receives SSID information 1051 and encryption key information 1052 as input, and displays, for example, the SSID and encryption key of a communication partner accessed by wireless device 453 included in the terminal. (This display is referred to as the first display in this embodiment.)

[0351] For example, after the first display, wireless device 453 included in terminal 1050 in Fig. 10 receives SSID information 1051 and encryption key information 1052 as input, and establishes a connection with one of base stations (or APs) 470-1, 470-2, or 470-3 (for example, the connection is assumed to be made using radio waves). At this time, when the connected base station communicates with wireless device 453 included in terminal 1050 in Fig. 22, it also transmits a modulated signal using, for example, radio waves.

[0352] Thereafter, wireless device 453 included in terminal 1050 in FIG. 22 receives data 1053 and control signal 1054 as input, modulates data 1053 under the control of control signal 1054, and transmits the modulated signal as radio waves.

[0353] Then, for example, the connected base station (or AP) transmits data to the network (471-1, 471-2, or 471-3) and receives data from the network (472-1, 472-2, or 472-3). After that, for example, the connected base station transmits a modulated signal as radio waves to terminal 1050 in FIG. 22.

[0354] 22 performs processes such as demodulation and error correction decoding on the modulated signal received as radio waves, and acquires received data 1056. Display unit 157 performs display based on received data 1056.

[0355] Terminal 1050 in Fig. 22 receives a modulated signal transmitted by fifth device 1000. Note that in terminal 1050 in Fig. 22, components that operate in the same manner as terminal 150 in Fig. 1 and terminal 450 in Fig. 4 are assigned the same numbers.

[0356] Light receiving unit 151, such as an image sensor such as CMOS or organic CMOS, included in terminal 1050 receives the modulated signal transmitted by fifth device 1000. Then, receiving unit 153 receives received signal 152 received by light receiving unit 151 as input, performs processing such as demodulation and error correction decoding of the received signal, and outputs received data 154.

[0357] The data analyzer 155 receives the received data 154 as input, and outputs, from the received data, for example, SSID information 1051 of the destination base station (470-1, 470-2, 470-3) and encryption key information 1052 for communicating with the destination base station (470-1, 470-2, 470-3). For example, in a wireless LAN (Local Area Network), encryption methods include WEP (Wired Equivalent Privacy), WPA (Wi-Fi Protected Access), and WPA2 (Wi-Fi Protected Access 2) (PSK (Pre-Shared Key) mode, EAP (Extended Authentication Protocol) mode). However, the encryption method is not limited to these.

[0358] Display unit 157 receives SSID information 1051 and encryption key information 1052 as input, and displays, for example, the SSID and encryption key of a communication partner accessed by wireless device 453 included in the terminal. (This display is referred to as the first display in this embodiment.)

[0359] For example, after the first display, wireless device 453 included in terminal 1050 in Fig. 10 receives SSID information 1051 and encryption key information 1052 as input, and establishes a connection with one of base stations (or APs) 470-1, 470-2, or 470-3 (for example, the connection is assumed to be made using radio waves). At this time, when the connected base station communicates with wireless device 453 included in terminal 1050 in Fig. 22, it also transmits a modulated signal using, for example, radio waves.

[0360] Thereafter, wireless device 453 included in terminal 1050 in FIG. 22 receives data 1053 and control signal 1054 as input, modulates data 1053 under the control of control signal 1054, and transmits the modulated signal as radio waves.

[0361] Then, for example, the connected base station (or AP) transmits data to the network (471-1, 471-2, or 471-3) and receives data from the network (472-1, 472-2, or 472-3). After that, for example, the connected base station transmits a modulated signal as radio waves to terminal 1050 in FIG. 22.

[0362] 22 performs processes such as demodulation and error correction decoding on the modulated signal received as radio waves, and acquires received data 1056. Display unit 157 performs display based on received data 1056.

[0363] In the case of Fig. 22, it is assumed that there are three types of frame configurations for the modulated signal transmitted by fifth device 1000 in Fig. 22. Fig. 23 shows 2300-1 frame #1, which is one of the three types of frame configurations, Fig. 24 shows 2300-2 frame configuration #2, which is one of the three types of frame configurations, and Fig. 25 shows 2300-3 frame configuration #3, which is one of the three types of frame configurations.

[0364] Fig. 23 shows an example of the configuration of 2300-1 frame #1 of a modulated signal transmitted by fifth device 1000 of Fig. 22. In Fig. 23, the horizontal axis represents time, and the same symbols as in Fig. 2 and Fig. 11 are assigned the same numbers and will not be described again. 2300-1 frame #1 of Fig. 23 is a frame for transmitting information on the SSID of base station #1 of 470-1 of Fig. 22 and information on the encryption key of base station #1 of 470-1 of Fig. 22 (encryption key for accessing base station #1 of 470-1).

[0365] Symbol 2301-1 relating to SSID in Fig. 23 is a symbol for transmitting information 1001-1 relating to SSID in Fig. 22. Symbol 2301-1 relating to SSID in Fig. 23 is a symbol for fifth device 1000 in Fig. 22 to transmit the SSID of base station #1 470-1 in Fig. 22.

[0366] Symbol 2302-1 relating to the encryption key in Fig. 23 is a symbol for transmitting information 1001-2 relating to the encryption key in Fig. 22. Symbol 2302-1 relating to the encryption key in Fig. 23 is a symbol for fifth device 1000 in Fig. 22 to transmit the encryption key of base station #1 470-1 in Fig. 22 (encryption key for accessing base station #1 470-1).

[0367] The fifth device transmits preamble 201, control information symbol 202, symbol 2301-1 related to SSID, symbol 2302-1 related to encryption key, and data symbol 1102. Note that fifth device 1000 in Fig. 22 may transmit 2300-1 frame #1 including symbols other than those shown in Fig. 23. Furthermore, the configuration of 2300-1 frame #1, including the order in which the symbols are transmitted, is not limited to the configuration in Fig. 23.

[0368] Fig. 24 shows an example of the configuration of 2300-2 frame #2 of the modulated signal transmitted by fifth device 1000 in Fig. 22. In Fig. 24, the horizontal axis represents time, and the same symbols as in Fig. 2 and Fig. 11 are assigned the same numbers and will not be described again. 2300-2 frame #2 in Fig. 24 is a frame for transmitting information on the SSID of base station #2 of 470-2 in Fig. 22 and information on the encryption key of base station #2 of 470-2 in Fig. 22 (encryption key for accessing base station #2 of 470-2).

[0369] Symbol 2301-2 relating to SSID in Fig. 24 is a symbol for transmitting information 1001-1 relating to SSID in Fig. 22. Symbol 2301-2 relating to SSID in Fig. 24 is a symbol for fifth device 1000 in Fig. 22 to transmit the SSID of base station #2 470-2 in Fig. 22.

[0370] Symbol 2302-2 relating to the encryption key in Fig. 24 is a symbol for transmitting information 1001-2 relating to the encryption key in Fig. 22. Symbol 2302-2 relating to the encryption key in Fig. 24 is a symbol for fifth device 1000 in Fig. 22 to transmit the encryption key of base station #2 470-2 in Fig. 22 (encryption key for accessing base station #2 470-2).

[0371] The fifth device transmits preamble 201, control information symbol 202, SSID-related symbol 2301-2, encryption key-related symbol 2302-2, and data symbol 1102. Note that fifth device 1000 in Fig. 22 may transmit 2300-2 frame #2 including symbols other than those shown in Fig. 24. Furthermore, the configuration of 2300-2 frame #2, including the order in which the symbols are transmitted, is not limited to the configuration in Fig. 24.

[0372] Fig. 25 shows an example of the configuration of 2300-3 frame #3 of the modulated signal transmitted by fifth device 1000 in Fig. 22. In Fig. 25, the horizontal axis represents time, and the same symbols as in Fig. 2 and Fig. 11 are assigned the same numbers and will not be described again. 2300-3 frame #3 in Fig. 25 is a frame for transmitting information on the SSID of base station #3 470-3 in Fig. 22 and information on the encryption key of base station #3 470-3 in Fig. 22 (encryption key for accessing base station #3 470-3).

[0373] Fig. 25 shows an example of the configuration of 2300-3 frame #3 of the modulated signal transmitted by fifth device 1000 in Fig. 22. In Fig. 25, the horizontal axis represents time, and the same symbols as in Fig. 2 and Fig. 11 are assigned the same numbers and will not be described again. 2300-3 frame #3 in Fig. 25 is a frame for transmitting information on the SSID of base station #3 470-3 in Fig. 22 and information on the encryption key of base station #3 470-3 in Fig. 22 (encryption key for accessing base station #3 470-3).

[0374] Symbol 2301-3 relating to SSID in Fig. 25 is a symbol for transmitting information 1001-1 relating to SSID in Fig. 22. Symbol 2301-3 relating to SSID in Fig. 25 is a symbol for fifth device 1000 in Fig. 22 to transmit the SSID of base station #3 470-3 in Fig. 22.

[0375] Symbol 2302-3 relating to the encryption key in Fig. 25 is a symbol for transmitting information 1001-2 relating to the encryption key in Fig. 22. Symbol 2302-3 relating to the encryption key in Fig. 25 is a symbol for fifth device 1000 in Fig. 22 to transmit the encryption key of base station #3 470-3 in Fig. 22 (encryption key for accessing base station #3 470-3).

[0376] The fifth device transmits preamble 201, control information symbol 202, SSID-related symbol 2301-3, encryption key-related symbol 2302-3, and data symbol 1102. Note that fifth device 1000 in Fig. 22 may transmit 2300-3 frame #3 including symbols other than those shown in Fig. 25. Furthermore, the configuration of 2300-3 frame #3, including the order in which the symbols are transmitted, is not limited to the configuration in Fig. 25.

[0377] Figure 26 shows an example of a transmission method when the fifth device in Figure 22 transmits "Frame #1 of 2300-1 in Figure 23," "Frame #2 of 2300-2 in Figure 24," and "Frame #3 of 2300-3 in Figure 25," and in Figure 26, the horizontal axis represents time.

[0378] In Fig. 26, "frame #1 group transmission" 2601-1 and 2601-2 transmit one or more frames #1 of 2300-1 in Fig. 23. "frame #2 group transmission" 2602-1 and 2602-2 transmit one or more frames #2 of 2300-2 in Fig. 24. "frame #3 group transmission" 2603-1 and 2603-2 transmit one or more frames #3 of 2300-3 in Fig. 25.

[0379] A detailed explanation of this will be given below.

[0380] It was stated that "In 'Transmit Frame #1 Group' 2601-1 and 2601-2, one or more frames #1 of 2300-1 in FIG. 23 are transmitted." This point will be explained below.

[0381] For example, if an image sensor such as a CMOS or organic CMOS is used in the light receiving unit 151, the received signal may be processed on a frame-by-frame basis for video or still images. For example, if "4K 30p" is written for video, it means that the number of pixels per frame is 3840 x 2160, and the number of frames per second is 30.

[0382] Therefore, if the fifth device in Figure 22 transmits a modulated signal configured such that one frame contains "frame #1 of 2300-1 in Figure 23," "frame #2 of 2300-2 in Figure 24," and "frame #3 of 2300-3 in Figure 25," it becomes difficult for terminal 1000 in Figure 22 to select a base station to access from multiple base stations.

[0383] Therefore, we propose a frame structure as shown in FIG.

[0384] (Method 1-1) In method 1-1, multiple frames #1 of 2300-1 in Figure 23 exist in "Frame #1 group transmission" 2601-1, 2601-2, so that the time period occupied by "Frame #1 group transmission" is longer than the time of a frame in a video or still image.

[0385] By doing this, terminal 1050 in FIG. 22 can be prevented from receiving a modulated signal from fifth device 1000 in which "frame #1 of 2300-1 in FIG. 23," "frame #2 of 2300-2 in FIG. 24," and "frame #3 of 2300-3 in FIG. 25" exist within one frame of a moving image or still image, thereby making it easier for terminal 1050 in FIG. 22 to select a base station to access from multiple base stations.

[0386] (Method 2-1) In method 2-1, the time period occupied by frame #1 of 2300-1 in Fig. 23 is set to be longer than the time period occupied by frames in a moving image or a still image. For example, symbol 2301-1 relating to SSID in Fig. 23 may include multiple pieces of "information on the SSID of base station #1" (repeatedly including "information on the SSID of base station #1"), and symbol 2302-1 relating to encryption key may include multiple pieces of "information on the encryption key of base station #1 (information on the encryption key for connecting to base station #1)" (repeatedly including "information on the encryption key of base station #1 (information on the encryption key for connecting to base station #1)").

[0387] By doing this, terminal 1050 in FIG. 22 can be prevented from receiving a modulated signal from fifth device 1000 in which "frame #1 of 2300-1 in FIG. 23," "frame #2 of 2300-2 in FIG. 24," and "frame #3 of 2300-3 in FIG. 25" exist within one frame of a moving image or still image, thereby making it easier for terminal 1050 in FIG. 22 to select a base station to access from multiple base stations.

[0388] Similarly, the "frame #2 group transmission" 2602-1 and 2602-2 may have the following configuration.

[0389] (Method 1-2) In method 1-2, multiple frames #2 of 2300-2 in Figure 24 exist in "Frame #2 group transmission" 2602-1, 2602-2, so that the time period occupied by "Frame #2 group transmission" is longer than the time of a frame in a video or still image.

[0390] (Method 2-2) In method 2-2, the time period occupied by frame #2 of 2300-2 in Fig. 24 is set to be longer than the time period occupied by a frame in a moving image or a still image. For example, symbol 2301-2 relating to SSID in Fig. 24 may include multiple pieces of "information on the SSID of base station #2" (repeatedly including "information on the SSID of base station #2"), and symbol 2302-2 relating to encryption key may include multiple pieces of "information on the encryption key of base station #2 (information on the encryption key for connecting to base station #2)" (repeatedly including "information on the encryption key of base station #2 (information on the encryption key for connecting to base station #2)").

[0391] Similarly, it is preferable that "frame #3 group transmission" 2603-1 and 2603-2 have the following configuration.

[0392] (Methods 1-3) In method 1-3, multiple frames #3 of 2300-3 in Figure 25 exist in "Frame #3 group transmission" 2603-1, 2603-2, so that the time period occupied by "Frame #3 group transmission" is longer than that of a frame in a video or still image.

[0393] (Method 2-3) As a method 2-3, the time period occupied by frame #3 of 2300-3 in Fig. 25 is set to be longer than the time period occupied by frames in a moving image or a still image. For example, symbol 2301-3 relating to SSID in Fig. 25 may include multiple pieces of "information on the SSID of base station #3" (repeatedly including "information on the SSID of base station #3"), and symbol 2302-3 relating to encryption key may include multiple pieces of "information on the encryption key of base station #3 (information on the encryption key for connecting to base station #3)" (repeatedly including "information on the encryption key of base station #3 (information on the encryption key for connecting to base station #3)").

[0394] Next, the effect when the fifth device 1000 in FIG. 22 transmits a frame as shown in FIGS. 23 to 26 will be described.

[0395] Consider the area 2700 in Fig. 27. The fifth device 1000 in Fig. 22 is placed in ○ 2701-1, 2701-2, 2701-3, 2701-4, 2701-5, 2701-6, 2701-7, 2701-8, 2701-8, 2701-9, and 2701-10. Then, the base station #1 of 470-1 in Fig. 22 is placed in ◎ 2702-1, the base station #2 of 470-2 in Fig. 22 is placed in ◎ 2702-2, and the base station #3 of 470-3 in Fig. 22 is placed in ◎ 2702-3.

[0396] For example, it is assumed that there are 99 terminals equipped with the configuration of 1050 in FIG.

[0397] At this time, for example, the fifth devices 2701-5 and 2701-10 both transmit information on the SSID of base station #3 of 470-3, and also transmit information on the encryption key for accessing base station #3 of 470-3 (because the nearest base station to the fifth devices 2701-5 and 2701-10 is base station #3 of 470-3).

[0398] As a result, all 99 terminals having the configuration of 1050 in Figure 22 will access base station #3 at 470-3 in Figure 22, and there is a high possibility that there will be terminals having the configuration of 1050 in Figure 22 that will have difficulty accessing base station #3 at 470-3 in Figure 22.

[0399] Taking this into consideration, by controlling the 99 terminals equipped with the configuration of 1050 in Figure 22 to access base station #1 (2702-1) at 470-1 in Figure 22, base station #2 (2702-2) at 470-2 in Figure 22, and base station #3 (2702-3) at 470-3 as evenly as possible, it is possible to achieve the effect of reducing the number of terminals that have difficulty accessing base stations, as mentioned above.

[0400] In this embodiment, when the fifth device 1000 of Fig. 22 transmits a frame as shown in Fig. 23 to Fig. 26, the timing at which the 99 terminals having the configuration of 1050 of Fig. 22 access the fifth device of Fig. 22 will generally differ, so "control is performed so that the 99 terminals having the configuration of 1050 of Fig. 22 access base station #1 (2702-1) of 470-1 of Fig. 22, base station #2 (2702-2) of 470-2 of Fig. 22, and base station #3 (2702-3) of 470-3 as evenly as possible." Therefore, it is possible to obtain the effect of reducing the presence of terminals that have difficulty in accessing base stations, as mentioned above.

[0401] Note that Figure 26 shows an example of a transmission method when the fifth device in Figure 22 transmits "frame #1 of 2300-1 in Figure 23," "frame #2 of 2300-2 in Figure 24," and "frame #3 of 2300-3 in Figure 25," but the transmission method when the fifth device in Figure 22 transmits "frame #1 of 2300-1 in Figure 23," "frame #2 of 2300-2 in Figure 24," and "frame #3 of 2300-3 in Figure 25" is not limited to this.

[0402] Note that Figure 26 shows an example of a transmission method when the fifth device in Figure 22 transmits "frame #1 of 2300-1 in Figure 23," "frame #2 of 2300-2 in Figure 24," and "frame #3 of 2300-3 in Figure 25," but the transmission method when the fifth device in Figure 22 transmits "frame #1 of 2300-1 in Figure 23," "frame #2 of 2300-2 in Figure 24," and "frame #3 of 2300-3 in Figure 25" is not limited to this.

[0403] For example, while FIG. 26 shows a configuration in which "frame #1 group transmission," "frame #2 group transmission," and "frame #3 group transmission" are repeatedly transmitted in this order, "frame #1 group transmission," "frame #2 group transmission," and "frame #3 group transmission" do not have to be transmitted in the order shown in FIG. 26. For example, "frame group 1 transmission," "frame group #2 transmission," and "frame group #3 transmission" may be transmitted randomly over time, or "frame group 1 transmission," "frame group #2 transmission," and "frame group #3 transmission" may be transmitted in a regular order different from that shown in FIG. 26. At least, it is sufficient if the fifth device in FIG. 22 transmits "frame #1 group transmission," "frame #2 group transmission," and "frame #3 group transmission."

[0404] Also, in Figure 26, "frame #1 group transmission," "frame #2 group transmission," and "frame #3 group transmission" are transmitted consecutively, but they do not necessarily have to be transmitted consecutively. For example, in Figure 26, there may be a time interval between frame #1 group 2601-1 and frame #2 group transmission 2602-2.

[0405] 26 is configured with only "frame #1 group transmission," "frame #2 group transmission," and "frame #3 group transmission," but other symbols and other frames may also be present. Furthermore, although three base stations are shown in FIGS. 26 and 22, the number of base stations is not limited to this, and as long as there are two or more base stations, operation similar to that when there are three base stations is possible. Therefore, for example, when there are N base stations (N is an integer greater than or equal to 2), when transmission as shown in FIG. 26 is performed, a "frame #k group transmission" will be present. Note that k is an integer greater than or equal to 1 and less than or equal to N. The "frame #k group transmission" will include a symbol related to the SSID (information about the SSID of base station #k) and a symbol related to the encryption key (information about the encryption key for accessing base station #k).

[0406] Fig. 12 shows an example of a frame structure of a modulated signal transmitted by radio equipment 453 included in terminal 1050 in Fig. 22. In Fig. 12, the horizontal axis represents time. As shown in Fig. 12, radio equipment 453 included in terminal 1050 in Fig. 22 transmits, for example, preamble 1201, and then transmits control information symbol 1202 and information symbol 1203.

[0407] In this case, the preamble 1201 is a symbol used by the base stations (or APs) 470-1, 470-2, and 470-3 that receive the modulated signal transmitted by the wireless device 453 of the terminal 1050 in FIG. 22 to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, and frequency offset estimation.

[0408] The control information symbol 1202 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the base stations (or APs) 470-1, 470-2, and 470-3 will perform demodulation of the modulated signal based on the information contained in this control information symbol 1202.

[0409] Information symbol 1203 is a symbol for transmitting data by radio equipment 453 of terminal 1050 in FIG.

[0410] Note that radio device 453 of terminal 1050 in FIG. 22 may transmit a frame including symbols other than those shown in FIG. 12 (for example, a frame including a pilot symbol (reference symbol) in the middle of information symbols). Also, the frame configuration, including the order in which symbols are transmitted, is not limited to that in FIG. 12. In FIG. 12, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0411] Figure 7 shows an example of the frame structure of modulated signals transmitted by base stations 470-1, 470-2, and 470-3 of Figure 22. The horizontal axis in Figure 7 represents time. As shown in Figure 7, base stations 470-1, 470-2, and 470-3 transmit, for example, preamble 701, followed by control information symbol 702 and information symbol 703.

[0412] In this case, the preamble 701 is assumed to be a symbol used by the radio device 453 of the terminal 1050 in FIG. 22, which receives the modulated signals transmitted by the base stations 470-1, 470-2, and 470-3, to perform, for example, signal detection, time synchronization, frame synchronization, frequency synchronization, and frequency offset estimation.

[0413] The control information symbol 702 contains data such as the error correction coding method used to generate the modulated signal, information about the modulation method, information about the frame structure, and information about the transmission method, and the radio device 453 of the terminal 1050 in Figure 22 will perform demodulation of the modulated signal based on the information in this symbol.

[0414] Information symbols 703 are symbols used by base stations (or APs) 470-1, 470-2, and 470-3 in FIG. 22 to transmit data.

[0415] Note that the base stations (or APs) 470-1, 470-2, and 470-3 in FIG. 22 may transmit frames including symbols other than those shown in FIG. 7 (for example, frames including pilot symbols (reference symbols) in the middle of information symbols). Also, the frame configuration, including the order in which symbols are transmitted, is not limited to that shown in FIG. 7. In addition, in FIG. 7, multiple symbols may exist in the frequency axis direction, that is, symbols may exist on multiple frequencies (multiple carriers).

[0416] Fig. 28 is a flowchart showing an example of the processing performed by the "fifth device 1000," "terminal 1050," and "base station #X (or AP #X)" in Fig. 22. Note that X is 1, 2, or 3.

[0417] First, as shown in 2801 in FIG. 28, the fifth device 1000 in FIG. 22 transmits a modulated signal having the frame structure shown in FIG.

[0418] Then, as shown in 2802 of FIG. 28, the modulated signal transmitted by fifth device 1000 of FIG. 22 is received, and terminal 1050 of FIG. 22 selects the base station to access from base station #1 of 470-1, base station #2 of 470-2, and base station #3 of 470-3 of FIG. 22.

[0419] This point will now be explained. Terminal 1050 in FIG. 22 attempts to access a base station and receives a modulated signal transmitted by fifth device 1000 in FIG. 22. At this time, for example, in one frame of a moving image or still image, one of "frame #1 group transmission," "frame #2 group transmission," or "frame #3 group transmission" in FIG. 26 is obtained. Then, based on the obtained base station information (for example, SSID), terminal 1050 in FIG. 22 determines the base station to be accessed by terminal 1050 to be one of base station #1 470-1, base station #2 470-2, or base station #3 470-3 in FIG. 22.

[0420] As shown in 2803 in FIG. 28, the modulated signal transmitted by the fifth device 1000 in FIG. 22 is received, and the terminal 1050 in FIG. 22 acquires the SSID of the base station #X that the terminal 1050 accesses.

[0421] Additionally, as in 2804 in FIG. 28, the terminal 1050 in FIG. 22 obtains an encryption key to be used for communication with the base station #X that the terminal accesses.

[0422] Then, terminal 1050 in FIG. 22 establishes a connection with base station #X via radio waves (2805).

[0423] In response to the response from base station #X, terminal 1050 in FIG. 22 completes connection with base station #X, as shown in 2806 in FIG.

[0424] Then, as in 1307 in FIG. 28, terminal 1050 in FIG. 22 transmits connection destination information to base station #X using radio waves.

[0425] 28, base station #X obtains information to be transmitted to terminal 1050 in FIG. 22 from the network.

[0426] Then, as shown in 2809 in FIG. 28, base station #X transmits the obtained information to terminal 1050 in FIG. 22 using radio waves, and terminal 1050 in FIG. 22 receives the information.

[0427] For example, terminal 1050 in FIG. 22 acquires necessary information from the network via base station #X when necessary.

[0428] As described above, the terminal connects to the base station (or AP) based on the SSID information and encryption key information transmitted from the fifth device and obtains the information, thereby achieving the effect of being able to safely obtain the information via the base station (or AP) whose security is guaranteed. This is because when the information is obtained from a modulated signal of visible light, it is easy for the user to determine whether the source of the information is safe because it is visible light.

[0429] For example, if the SSID is obtained from the modulated signal of radio waves transmitted by a wireless LAN, it is difficult for the user to identify the device that transmitted the radio waves. Therefore, in terms of ensuring the security of information, it is more appropriate to obtain the SSID using visible light communication.

[0430] In this embodiment, the fifth device transmits encryption key information. However, if the base station (or AP) is not performing encrypted communication using an encryption key, the fifth device can be implemented in the same manner by transmitting only information related to the SSID without transmitting encryption key information, and by simply deleting the configuration related to the encryption key.

[0431] Furthermore, the configuration of the fifth device is not limited to the configuration shown in Figure 22, and the configuration of the terminal is not limited to the configuration shown in Figure 22, and the connection destination and configuration method of base stations #1, #2, and #3 are not limited to those shown in Figure 22.

[0432] When implemented as in this embodiment, if there are multiple terminals in a certain area, the effect can be achieved of reducing the number of terminals that have difficulty accessing the base station.

[0433] In addition, in Figure 27, the frame structures of the modulated signals transmitted by the fifth devices located at ○ 2701-1, 2701-2, 2701-3, 2701-4, 2701-5, 2701-6, 2701-7, 2701-8, 2701-8, 2701-9, and 2701-10 may all be the same as in Figure 26, or the modulated signals transmitted by the fifth devices may each have a different frame structure, or there may be multiple fifth devices transmitting modulated signals with the same frame structure.

[0434] (Embodiment 8) From the embodiments described so far, it can be seen that a transmitting device equipped with a light source and illumination and transmitting an optically modulated signal may be configured to obtain data to be transmitted using the optically modulated signal from an external device such as a server and update the transmission data each time, because this provides the effect of enabling the data desired by the user or device to be updated successively.

[0435] In the following, an example of a communication system relating to the above will be described.

[0436] 29 shows an example of the configuration of a device related to the transmission of an optically modulated signal in this embodiment. The device related to the transmission of an optically modulated signal is made up of a communication device 2900 for PLC (Power line communication) and a communication device 2950 that transmits the optically modulated signal.

[0437] The modulation unit 2903 in the PLC communication device 2900 receives as input data 2901 and a control signal 2902, and performs error correction coding and mapping based on the set modulation method based on information contained in the control signal 2902, such as the error correction coding method (error correction code, coding rate, code length (block length), etc.) and modulation method, to generate and output a modulated signal 2904.

[0438] It is assumed that the data 2901 includes "data transmitted by the optical modulation signal transmitted by the device 2950."

[0439] Transmitting unit 2905 receives modulated signal 2904 as input, performs signal processing, generates and outputs transmission signal 2906. Note that transmitting unit 2905 may perform signal processing related to Orthogonal Frequency Division Multiplexing (OFDM) to generate and output transmission signal 2906 based on the OFDM system. Transmitting unit 2905 may also perform signal processing related to wavelet OFDM to generate and output transmission signal 2906 based on the wavelet OFDM system. Note that, although transmission signals of multi-carrier systems such as OFDM and wavelet OFDM have been described, the present invention is not limited to these, and transmission signals of single-carrier systems and spread spectrum communication systems may also be used. Note that non-patent documents 2 and 3 describe the wavelet OFDM system.

[0440] A feature of PLC communication device 2900 is that the transmission signal is a signal having a frequency spectrum from DC (Direct Current) to N [Hz], where N is a real number greater than 0. However, the transmission signal does not necessarily have a spectrum at all frequencies from DC (Direct Current) to N [Hz]. Therefore, it can also be said that transmission unit 2905 does not include a frequency conversion unit (RF (Radio Frequency) unit).

[0441] Transmitted signal 2006 passes through a power line and is input to communication device 2950 as received signal 2908. The power line containing transmitted signal 2006 also provides power to device 2950. Demodulator 2953 receives received signal 2908, performs decoding processes such as demapping and error correction decoding, and outputs received data 2954.

[0442] The storage unit 2955 receives the received data 2954 as input, and if it determines that the received data 2954 is update data, it stores the received data 2954 or a part of the received data 2954. The transmission unit 2957 receives the stored data 2956 as input.

[0443] Alternatively, the storage unit 2955 may determine that the received data 2954 is update data by using the control signal 2990.

[0444] Transmitting unit 2957 receives stored data 2956, performs modulation and other processing, and generates and outputs transmit signal 2958. At this time, no frequency conversion is performed. (Therefore, transmit signal 2958 is a signal having a frequency spectrum from DC to P [Hz] (P is a real number greater than 0).) AC-DC converter 2951 receives received signal 2980 as input, converts received signal 2980 present on AC into a signal on DC, and outputs converted signal 2952 .

[0445] Signal selection unit 2960 receives transmission signal 2958, converted signal 2952, and control signal 2959 as input, selects either transmission signal 2958 or converted signal 2952 based on control signal 2959, and outputs the selected signal as selection signal 2961. Selection signal 2961 is then transmitted from light source 2962.

[0446] When the signal selection section 2960 selects the converted signal 2952 as the selected signal 2961 , the selected signal 2961 may include a signal other than the converted signal 2952 .

[0447] As described above, by selectively switching and transmitting the transmission signal 2958 and the converted signal 2952, it is possible to obtain data desired by a user or device, and it is also possible to obtain the effect of allowing a user or device to obtain desired data more flexibly by transmitting, for example, urgent, sudden, or necessary information using the converted signal 2952. Furthermore, by AC-DC converting the modulated signal generated for PLC and transmitting it as an optical modulated signal, it is possible to relay the modulated signal for PLC as an optical modulated signal with a small circuit scale (because the modulated signal for PLC has the frequency spectrum described previously), and it is possible to transmit desired data to more users and devices.

[0448] Fig. 30 shows an example of the configuration of a device related to the transmission of an optically modulated signal in this embodiment, which is different from Fig. 29. In Fig. 30, components that operate in the same way as in Fig. 29 are given the same numbers, and descriptions thereof will be omitted.

[0449] Transmitting device 3003 receives data 3001 and external data 3002 as input, performs processes such as error correction coding and modulation, and generates and outputs transmission signal 3004. It is assumed that external data 3002 includes, for example, instruction information for updating data stored in memory unit 2955. In other words, it is assumed that communication device 2950 transmits an update request for data stored in memory unit 2955 to communication device 2900.

[0450] The transmitted signal 3004 passes through a propagation channel 3005 and is input to the communication device 2900 as a received signal 3006 .

[0451] A receiving device 3007 receives a received signal 3006 as input, performs processing such as demapping and error correction decoding, and outputs received data 3008 .

[0452] The modulation unit 2903 determines whether to transmit update data for the storage unit 2955 based on the information "data update request for the storage unit 2955 from the communication device 2950" included in the received data 3008.

[0453] By operating as described above, the communication system of FIG. 30 can obtain the same effects as those explained in the explanation of FIG.

[0454] An example of the operation of the AC-DC conversion unit 2951 described above will be described below.

[0455] The AC-DC converter 2951 separates AC power components having an AC power frequency of, for example, 50 Hz or 60 Hz from signal components having frequencies higher than the AC power frequency from the received signal 2980. The separation of the AC power components from the signal components can be performed using, for example, a frequency filter such as a high-pass filter, a low-pass filter, or a band-pass filter, or a combination thereof.

[0456] The AC-DC converter 2951 performs AC-DC conversion on the separated AC power component to convert the AC power component into a DC power component, thereby generating a DC power component. The AC-DC converter 2951 superimposes the separated signal component on the DC power component to generate a converted signal 2952. Here, the process of superimposing the signal component on the DC power component is performed, for example, by coupling the signal component to a power line that supplies the DC power component via a coupling transformer or the like.

[0457] The DC power component onto which the signal component is superimposed does not necessarily have to be obtained by converting an AC power component into a DC power component, and the signal component may be superimposed on a DC power component generated by another component (not shown) included in communication device 2950. Furthermore, converted signal 2952 may be a signal including a signal component that does not include a DC power component.

[0458] Furthermore, the AC-DC converter 2951 may perform processing such as amplification using an amplifier on the separated signal components. This configuration makes it possible to control the intensity (or amplitude) of the signal components included in the optically modulated signal transmitted from the light source 2962, which may improve the reception quality of the optically modulated signal.

[0459] 29 and 30 have been described using an example in which PLC communication device 2900 superimposes a PLC signal on power line 2907 that supplies AC power, but communication device 2900 may superimpose a PLC signal on power line 2907 that supplies DC power. With this configuration, even if communication device 2950 does not include an AC-DC conversion unit, it can provide the signal component, i.e., the DC power on which the PLC signal is superimposed, as converted signal 2952 to signal selection unit 2960 and light source 2962, which may simplify the configuration of communication device 2950.

[0460] In the above explanation, the PLC transmission signal is DC (Direct Current). Although it has been explained that the spectrum does not necessarily exist at all frequencies, an example of the above-mentioned PLC transmission signal will be explained below.

[0461] For example, PLC signals may be signals based on a communication method using frequencies between 10 kHz and 450 kHz, known as low-speed PLC, or signals based on a communication method using frequencies between 2 MHz and 30 MHz or between 2 MHz and 80 MHz, known as high-speed PLC. Furthermore, a notch band, which is a frequency band that outputs less power than other frequencies or is not used for communication, may be provided in part of the frequency band used for communication. When a PLC signal with a notch band is transmitted as an optically modulated signal, the optical signal is intensity-modulated with a modulation signal that suppresses the notch band components. Methods for providing a notch band in a PLC transmission signal include suppressing the signal components in the notch band using a frequency filter such as a band elimination filter, or generating a modulation signal that does not use subcarriers in the notch band using a Wavelet-OFDM multicarrier system with deep filter characteristics.

[0462] In the above description, PLC communication using a power line as a transmission line has been taken as an example, but cables other than a power line, such as a coaxial cable, a twisted pair wire, or a telephone line, may also be used as the transmission line.

[0463] (Embodiment 9) In this embodiment, an example of the configuration of the transmitting device and receiving device described in this specification will be described. Note that a characteristic feature of the transmitting device in this embodiment is that it transmits a plurality of optical modulated signals.

[0464] Fig. 31 shows an example of the configuration of a transmitting device and a receiving device according to this embodiment. In Fig. 31, a transmitting device 3100 transmits a plurality of optically modulated signals, and a receiving device 3150 receives the plurality of optically modulated signals to obtain received data.

[0465] 31 transmits M optical modulated signals, where M is an integer of 2 or greater.

[0466] The transmitter 3102_i receives the data 3101_i and the control signal 3105 as input, performs error correction coding and signal processing based on the transmission method, based on the information on the error correction coding method and the information on the transmission method included in the control signal 3105, and generates and outputs the optical modulated signal 3103_i, where i is an integer between 1 and M.

[0467] The optically modulated signal 3103_i is then transmitted from the light source 3104_i.

[0468] A light receiving unit 3151 such as an image sensor receives light corresponding to the optical modulation signal 3103_i. At this time, the light receiving unit 3151 receives light corresponding to M optical modulation signals.

[0469] The light receiving unit 3151 outputs an optical reception signal 3152_i corresponding to the optical modulated signal 3103_i, where i is an integer between 1 and M inclusive.

[0470] The receiver 3153_i receives an optical reception signal 3152_i corresponding to the optical modulated signal 3103_i, performs processing such as demodulation and error correction decoding, and outputs reception data 3154_i corresponding to the data 3101_i.

[0471] The data acquisition unit 3155 receives data 3154_1, data 3154_2, . . . , data 3154_M as input, and generates and outputs data 3156.

[0472] Figure 32 shows an example of the configuration of a transmitting device and a receiving device according to this embodiment, which is different from that of Figure 31. In Figure 32, components that operate in the same way as in Figure 31 are given the same numbers.

[0473] Distribution unit 3202 receives information 3201 and control signal 3105 as input, performs error correction coding on the information based on information relating to the error correction coding method included in control signal 3105, and generates error correction coded data. Distribution unit 3202 then distributes the error correction coded data, and outputs error correction coded data A2001_i.

[0474] Note that the distribution to the M pieces of error-correction-coded data 3101_i may be performed in any manner. For example, the error-correction-coded data may be divided into M pieces, and each of the M divided data sequences may be assigned to the error-correction-coded data 3101_i. Alternatively, M data sequences consisting of the same data may be generated from the error-correction-coded data, and each data sequence may be assigned to the error-correction-coded data 3101_i. The method of assignment to the error-correction-coded data 3101_i is not limited to these, and it is also possible to generate M data sequences from the error-correction-coded data, and assign each data sequence to the error-correction-coded data 3101_i.

[0475] Transmitting unit 3102_i receives data 3101_i and control signal 3105 as input, performs signal processing based on the transmission method based on information about the transmission method included in control signal 3105, and generates and outputs optical modulated signal 3103_i, where i is an integer between 1 and M.

[0476] The optically modulated signal 3103_i is then transmitted from the light source 3104_i.

[0477] A light receiving unit 3151 such as an image sensor receives light corresponding to the optical modulation signal 3103_i. At this time, the light receiving unit 3151 receives light corresponding to M optical modulation signals.

[0478] The light receiving unit 3151 outputs an optical reception signal 3152_i corresponding to the optical modulated signal 3103_i, where i is an integer between 1 and M inclusive.

[0479] The receiver 3153_i receives an optical reception signal 3152_i corresponding to the optical modulated signal 3103_i, performs processing such as demodulation, and outputs reception data (log-likelihood ratio) 3154_i corresponding to the data 3101_i.

[0480] Error correction decoding section 3251 receives received data (log likelihood ratio) 3154_1, received data (log likelihood ratio) 3154_2, ..., received data (log likelihood ratio) 3154_M as input, performs error correction decoding, and outputs received data 3252.

[0481] When the above-described transmitting device and receiving device are used to implement each embodiment in this specification, the same can be implemented, and the effects described in each embodiment can be obtained in the same way.

[0482] (Embodiment 10) In this embodiment, a configuration of an apparatus related to the transmission of an optically modulated signal, which differs from the apparatus related to the transmission of an optically modulated signal described in the eighth embodiment of FIGS. 29 and 30, will be described.

[0483] FIG. 33 shows an example of the configuration of a device related to the transmission of an optically modulated signal, which differs from those in FIGS. 29 and 30. In FIG. 33, components that operate in the same manner as those in FIG. 29 are given the same numbers, and their explanation will be omitted.

[0484] A characteristic feature of FIG. 33 is that a communication device 2900 transmits an optically modulated signal.

[0485] The light source transmitter 3301 receives the modulated signal 2904, performs signal processing for the light source, and generates and outputs the modulated optical signal 3302. The modulated optical signal 3302 is then emitted as light from the light source 3303.

[0486] A receiving device 3305 receives a received signal 3304 corresponding to an optically modulated signal, and performs processing such as demodulation and error correction decoding to obtain received data.

[0487] By doing so, it is possible to obtain the effects described in the eighth embodiment, and by the communication device 2900 transmitting an optically modulated signal, it becomes possible for more communication devices to obtain information.

[0488] Figure 34 shows an example of the configuration of a device related to an optical modulation signal that is different from those in Figures 29, 30, and 33. In Figure 34, parts that operate in the same way as in Figures 29 and 33 are given the same numbers and their explanations are omitted.

[0489] FIG. 34 differs from FIG. 33 in that a transmitter 2905 generates an optical modulated signal 3401. Therefore, transmitter 2905 receives modulated signal 2904 as input, and generates and outputs a transmission signal 2906 for PLC and a transmission signal 3401 for optical communication (visible light communication). Note that both transmission signal 2906 for PLC and transmission signal 3401 for optical communication (visible light communication) are signals having a frequency spectrum from DC to N [Hz] (N is a real number greater than 0). However, a spectrum does not necessarily exist at all frequencies from DC to N [Hz]. Transmission signal 3401 for optical communication (visible light communication) is irradiated as light from light source 3303.

[0490] By doing so, it is possible to obtain the effects described in the eighth embodiment, and by the communication device 2900 transmitting an optically modulated signal, it becomes possible for more communication devices to obtain information.

[0491] Figure 35 is an example of the configuration of a transmitting device related to an optically modulated signal different from those in Figures 29, 30, and 33, and in Figure 35, components that operate in the same manner as in Figures 29, 30, and 33 are given the same numbers and will not be described. Therefore, the components in Figure 35 have already been described, so their description will be omitted.

[0492] By doing so, it is possible to obtain the effects described in the eighth embodiment, and by the communication device 2900 transmitting an optically modulated signal, it becomes possible for more communication devices to obtain information.

[0493] Figure 36A is an example of the configuration of a transmitting device related to an optically modulated signal different from those in Figures 29, 30, 33, and 34, and in Figure 36A, components that operate in the same manner as in Figures 29, 30, 33, and 34 are assigned the same numbers and will not be described. Therefore, the components in Figure 36A have already been described, so their description will be omitted.

[0494] By doing so, it is possible to obtain the effects described in the eighth embodiment, and by the communication device 2900 transmitting an optically modulated signal, it becomes possible for more communication devices to obtain information.

[0495] (Supplementary Note 2) At least one of the FPGA (Field Programmable Gate Array) and the CPU (Central Processing Unit) may be configured to download all or part of the software required to realize the communication method described in the present disclosure via wireless or wired communication. Furthermore, all or part of the software for updates may be downloaded via wireless or wired communication. The downloaded software may then be stored in a storage unit, and at least one of the FPGA and the CPU may be operated based on the stored software to perform the digital signal processing described in the present disclosure.

[0496] In this case, the device having at least one of the FPGA and the CPU may be connected to the communication modem wirelessly or via a wire, and the communication method described in this disclosure may be realized by this device and the communication modem.

[0497] For example, a communication device such as a base station, AP, or terminal described herein may include at least one of an FPGA and a CPU, and may have an interface for externally obtaining software for operating at least one of the FPGA and the CPU. Furthermore, the communication device may have a storage unit for storing the software obtained from the outside, and may operate the FPGA and CPU based on the stored software to realize the signal processing described in the present disclosure.

[0498] A first "car or vehicle" may be equipped with a transmitting device as described herein, and a second "car or vehicle" may be equipped with a receiving device as described herein, and data may be transmitted and received.

[0499] The "transmitting device or part of the functionality of the transmitting device" described in this specification may be connected to a first "car or vehicle" via an interface, and the "receiving device or part of the receiving device" described in this specification may be connected to a second "car or vehicle" via an interface, and data transmission by transmission and reception may be performed.

[0500] Furthermore, the first "car or vehicle" may be equipped with the transmitting device described in this specification, and data may be transmitted and received between this transmitting device and the receiving device described in this specification.

[0501] A second "car or vehicle" may be equipped with a receiving device as described herein, and data may be transmitted and received between this receiving device and a transmitting device as described herein.

[0502] Furthermore, the "transmitting device or part of the functionality of the transmitting device" described in this specification may be connected to a first "car or vehicle" via an interface, and data may be transmitted and received between this series of transmitting devices and the receiving device described in this specification.

[0503] The "receiving device or part of the receiving device" described in this specification may be connected to a second "car or vehicle" via an interface, and data may be transmitted and received between the transmitting device described in this specification and this set of receiving devices.

[0504] If a "car or vehicle" is equipped with a transmitting device or part of a transmitting device described in this specification, or if a "car or vehicle" is connected via an interface to a "transmitting device described in this specification" or "part of the functionality of a transmitting device described in this specification," the light source equipped in the "car or vehicle" may be used as the light source equipped in the transmitting device described in this specification.

[0505] For example, as shown in FIG. 36B, a car B100 has light sources B101_1, B101_2, B101_3, and B101_4, and one or more of these light sources may be used as light sources for transmitting optically modulated signals by the transmitting device described in this specification.

[0506] Furthermore, the transmitting device or a device connected to the transmitting device may have a function for selecting "which light source to use as a light source for transmitting an optically modulated signal by the transmitting device described in this specification" from among the multiple light sources mounted on the car B100. Furthermore, the brightness, irradiation angle, and position of the light source may be set together.

[0507] If "a car or vehicle is equipped with a receiving device or part of a receiving device described in this specification," or "a car or vehicle is connected to a receiving device described in this specification or part of the functions of a receiving device described in this specification via an interface," the light receiving unit (e.g., an image sensor, photodiode, etc.) equipped in the car or vehicle may be used as the light receiving unit equipped in the receiving device described in this specification.

[0508] For example, as shown in FIG. 36C, a vehicle B100 has light receiving units B201_1, B201_2, B201_3, B201_4, B201_5, and B201_6, and one or more of these light receiving units may be used as light receiving units for the receiving device described in this specification to receive optically modulated signals.

[0509] Furthermore, the receiving device or a device connected to the receiving device may have a function for selecting "which light receiving unit is to be used as the light receiving unit for the receiving device described in this specification to receive the optically modulated signal" from among the multiple light receiving units mounted on the car B100. Furthermore, the angle and position of the light receiving unit may be set accordingly.

[0510] Furthermore, the fact that the receiving device described in this specification is able to receive data may be displayed on the front panel of a car or in the cockpit of a vehicle.Also, the fact that the receiving device described in this specification is able to receive data may be notified to the user by vibrating the steering wheel of a car or a vibrator provided on the steering wheel.

[0511] Alternatively, a vehicle equipped with the receiving device described in this embodiment may be connected to a terminal via an interface, and data obtained by the receiving device may be stored in a storage unit provided in the terminal. Alternatively, the vehicle may also be equipped with a storage unit, and the received data may be stored in the vehicle. Alternatively, the received data may be stored in both a storage unit provided in the terminal and a storage unit provided in the vehicle.

[0512] In this specification, a server may provide an application for processing related to the receiving device, and a terminal may realize the functions of the receiving device described in this specification by installing this application. Note that the application may be provided to the terminal by connecting a communication device equipped with the transmitting device described in this specification to the server via a network, or the application may be provided to the terminal by connecting another communication device having a transmitting function to the server via a network.

[0513] Similarly, in this specification, a server may provide an application relating to processing related to the transmitting device, and a communication device may install the application to realize the functions of the transmitting device described in this specification. Note that a method is also conceivable in which the application is provided to another communication device by connecting the communication device to the server via a network.

[0514] In addition, the server may provide software relating to the light source provided in the transmitting device and the light receiving unit provided in the receiving device, and by obtaining this software, the light source provided in the transmitting device may be capable of transmitting optically modulated signals, and the light receiving unit provided in the receiving device may be capable of receiving optically modulated signals.

[0515] Furthermore, the transmitting device in this specification may have the functionality of a server, and the application that the transmitting device has may be provided to the communication device using some communication means, and the communication device may be able to realize the receiving device in this specification by using the application obtained by downloading it.

[0516] In this specification, the terms "illumination unit" and "light source" are used, but the light may be emitted by a display or projector that displays images, videos, advertisements, etc., and the light may contain an optical modulation signal. In other words, the "illumination unit" and "light source" may have a function other than emitting light. Furthermore, the "illumination unit" and "light source" may be composed of multiple "lights" and "light sources."

[0517] Furthermore, the transmission method used by the communication device that generates the optical modulated signal and emits light may be a method other than the transmission methods described in this specification, and the optical modulated signal may contain information other than that described in this specification.

[0518] Furthermore, the illumination / light source itself, such as an LED, may have the function of the transmitting device described in this specification.

[0519] Furthermore, the device for generating a transmission optical modulation signal may not include an illumination or light source, and the device for generating a transmission optical modulation signal may be connected to an illumination or light source via an interface.

[0520] The communication method between the transmitting device and the receiving device described in this embodiment may be the communication method shown in Fig. 36D. Fig. 36D will be described below.

[0521] The symbol mapping unit receives transmission data, performs mapping based on the modulation method, and outputs a symbol sequence (ci).

[0522] The pre-equalization processing unit receives a symbol sequence as input, performs pre-equalization processing on the symbol sequence in order to reduce the equalization processing on the receiving side, and outputs the pre-equalized symbol sequence.

[0523] The Hermitian symmetry processing unit receives the pre-equalization processed symbol sequence as input, performs subcarrier allocation for the pre-equalization processed symbol sequence so as to ensure Hermitian symmetry, and outputs parallel signals.

[0524] The inverse (fast) Fourier transform unit receives parallel signals as input, performs an inverse (fast) Fourier transform on the parallel signals, and outputs the signals after the inverse (fast) Fourier transform.

[0525] The parallel-to-serial and cyclic prefix adding unit receives the signal after inverse (fast) Fourier transform, performs parallel-to-serial conversion, adds a cyclic prefix, and outputs the signal after signal processing.

[0526] The digital-analog conversion unit receives the processed signal as input, performs digital-analog conversion, and outputs an analog signal, which is output as light from one or more LEDs, for example.

[0527] The equalization pre-processing unit and the Hermitian symmetry processing unit may not be necessary, that is, there may be cases where signal processing is not performed in the equalization pre-processing unit and the Hermitian symmetry processing unit.

[0528] The photodiode receives light as an input, and a TIA (Transimpedance Amplifier) ​​generates a received signal.

[0529] The analog-to-digital converter performs analog-to-digital conversion on the received signal and outputs a digital signal.

[0530] The cyclic prefix removal and serial-to-parallel conversion unit receives a digital signal as input, removes the cyclic prefix, then performs serial-to-parallel conversion, and receives a parallel signal as input.

[0531] The (fast) Fourier transform unit receives parallel signals as input, performs (fast) Fourier transform on them, and outputs the (fast) Fourier transformed signals.

[0532] The detection unit receives the Fourier transformed signal as input, performs detection, and outputs a received symbol sequence.

[0533] The symbol demapper receives a received symbol sequence as input, performs demapping, and obtains a received data sequence.

[0534] As described above, even if a transmitting device that transmits an optically modulated signal and a receiving device that receives an optically modulated signal are applied to each of the embodiments in this specification, each of the embodiments can be implemented in the same manner.

[0535] Furthermore, the communication method between the transmitting device and the receiving device in this embodiment may be the communication method described below.

[0536] <Line scan sampling> Smartphones, digital cameras, and other devices are equipped with image sensors such as CMOS (Complementary Metal Oxide Semiconductor) sensors. Images captured by CMOS sensors do not show the entire scene at exactly the same time. For example, they use a rolling shutter method in which the shutter operates row by row, reading out the amount of light received by the sensor for each line. Therefore, the start and end of light reception is controlled with a time lag for each line, taking into account the time required for readout. In other words, images captured by CMOS sensors are made up of many overlapping lines with a slight time lag in the exposure period.

[0537] This method takes advantage of the properties of CMOS sensors and enables faster reception of visible light signals.

[0538] That is, in the first example of the visible light communication method, by utilizing the fact that the exposure time varies slightly for each line, it is possible to measure the brightness and color of the light source at multiple points in time for each line from a single image (image captured by the image sensor), as shown in Figure 36E, and to capture signals modulated faster than the frame rate.

[0539] This sampling method is called "line scan sampling," and a row of pixels exposed at the same time is called an "exposure line."

[0540] Although "line scan sampling" can be achieved using the rolling shutter method with a CMOS sensor, "line scan sampling" can also be performed in the same way by using a sensor other than a CMOS sensor, such as a CCD (Charge-Coupled Device) sensor or an organic (CMOS) sensor, using the rolling shutter method.

[0541] However, with the imaging settings for the camera function (video or still image shooting function), even if a rapidly blinking light source is photographed, the blinking does not appear as a striped pattern along the exposure lines. This is because, with this setting, the exposure time is much longer than the blinking cycle of the light source, so as shown in Figure 36F, the change in brightness due to the blinking of the light source (light emission pattern) is uniformly averaged, and the change in pixel value between exposure lines becomes extremely small, resulting in a nearly uniform image.

[0542] In contrast to this, as shown in FIG. 36G, by setting the exposure time to be equal to or shorter than the blinking cycle of the light source, the blinking state (light emission pattern) of the light source can be observed as a change in luminance of the exposure line.

[0543] For example, the exposure lines are designed to be parallel to the long side of the image sensor. In this case, for example, if the frame rate is 30 fps (frames per second), a resolution of 1920 x 1080 will result in 32,400 or more samples per second, and a resolution of 3840 x 2160 will result in 64,800 or more samples per second.

[0544] <Application example of line scan sampling> While the above description describes line scan sampling, which reads out a signal indicating the amount of light received for each line, the optical signal sampling method using an image sensor such as a CMOS is not limited to this. Various methods can be used to receive optical signals, allowing for acquisition of sampled signals at a sampling rate higher than the frame rate used for normal video capture. For example, a global shutter method, which provides a shutter function for each pixel, may be used to control the exposure period for each pixel to read out a signal, or a method in which the exposure period is controlled for each group of multiple pixels arranged in a non-linear configuration to read out a signal. Alternatively, a method in which a signal is read out from the same pixel multiple times within a period equivalent to one frame at the frame rate used for normal video capture may be used.

[0545] <Frame Sampling> Furthermore, by using a frame rate system that provides a shutter function for each pixel, it is possible to sample optical signals even in a system that increases the frame rate.

[0546] This specification can be implemented using any of the methods described above, for example, "line scan sampling," "applications of line scan sampling," and "frame-based sampling."

[0547] <Light source and modulation method> In visible light communication, for example, a light-emitting diode (LED) can be used as a transmitter. LEDs are becoming popular as a light source for lighting or display backlights, and can be made to blink at high speed.

[0548] However, the light source used as a transmitter for visible light communication cannot be made to flicker freely for the purpose of visible light communication. If the change in brightness caused by visible light communication were noticeable to humans, it would impair the original function of the light source, such as lighting. Therefore, it is necessary to ensure that the transmitted signal does not flicker to the human eye and is illuminated at the desired brightness.

[0549] One modulation method that meets this requirement is 4PPM (4-Pulse Position Modulation). 4PPM is a method of expressing two bits by four combinations of light and dark from a light source, as shown in Figure 36H. Also, as shown in Figure 36H, 4PPM has three bright states and one dark state out of four, so the average brightness (average luminance) is 3 / 4 = 75%, regardless of the signal content.

[0550] For comparison, a similar method is the Manchester coding method shown in Figure 36I. The Manchester coding method expresses one bit using two states, and its modulation efficiency is the same as 4PPM (50%). However, since one of the two states is bright and the other is dark, the average brightness is 1 / 2 = 50%. In other words, 4PPM is more suitable as a modulation method for visible light communication than the Manchester coding method. However, even if the brightness change caused by visible light communication is noticeable to humans, communication performance is not degraded. Therefore, depending on the application, there is no problem in using a method that produces a brightness change noticeable to humans. Therefore, the transmitter (light source) may generate a modulated signal and turn on and irradiate the light source using a modulation method such as ASK (Amplitude Shift Keying), PSK (Phase Shift Keying), or PAM (Pulse Amplitude Modulation).

[0551] The communication method between the transmitting device and the receiving device described in this specification is not limited to the above example, and can be implemented in the same way using any wireless communication method using any frequency, such as light, visible light, infrared light, or ultraviolet light.

[0552] In this specification, "symbols related to location or position information," "symbols related to time information," "symbols related to SSID," "symbols related to access destinations," "symbols related to encryption keys," and the like are sometimes referred to as "symbols" in the description. However, each embodiment can be implemented in the same way even if they are referred to as "data," "information," "fields," "bits," or "areas" instead of "symbols." Furthermore, names other than "symbols," "data," "information," "fields," "bits," and "areas" may be used. Furthermore, the transmitting device may transmit data using any symbol configuration, such as "symbols related to location or position information," "symbols related to time information," "symbols related to SSID," "symbols related to access destinations," or "symbols related to encryption keys." What is important is that "data related to location or position information," "data related to time information," "data related to SSID," "data related to access destinations," "data related to encryption keys," and the like are transmitted to the communication partner.

[0553] In this specification, in a transmission device having a "light source", a "lighting unit", etc., the "light source" and the "lighting unit" may be made up of a plurality of "light sources" and a plurality of "lights".

[0554] (Embodiment A1) In this embodiment, a method and a system for receiving an optically modulated signal will be described.

[0555] FIG. 37 shows a system configured with a communication device according to this embodiment.

[0556] A communication device (for example, a terminal) 3700 is a device that receives an optically modulated signal. An optical receiver 3702 receives an optically modulated signal 3701 and outputs a received signal 3704.

[0557] Storage unit 3704 receives and stores received signal 3703. Storage unit 3704 then outputs the stored data as stored data 3705.

[0558] Transmitting device 3707 receives data 3706 and stored data 3705 as input, performs error correction coding, modulation, and other processing, and outputs modulated signal 3708 .

[0559] Receiving device 3701 of communication device (e.g., base station, AP (Access Point), etc.) 3750 receives modulated signal 3708 transmitted by communication device 3700, that is, receives modulated signal 3708 as input. Receiving device 3701 performs processes such as demodulation and error correction decoding, and outputs received data 3752.

[0560] The received data 3752 is delivered as data 3771 to a server 3772 via a network 3770 .

[0561] The server 3772 receives the data 3771 as input, performs demodulation and error correction decoding of the optically modulated signal 3701, and obtains and outputs the data 3773 contained in the optically modulated signal 3701.

[0562] Then, data 3773 is input as data 3753 to transmitting device 3754 via network 3770. Transmitting device 3754 included in communication device 3750 receives data 3753 as input, performs error correction coding, modulation, and other processing, and outputs modulated signal 3755.

[0563] A receiving device 3720 included in the communication device 3700 receives modulated signal 3755 as input, performs processing such as demodulation and error correction decoding, and obtains and outputs received data 3721. At this time, received data 3721 becomes the data contained in optical modulated signal 3701.

[0564] The operation of FIG. 37 will be described with reference to FIG.

[0565] 38, a "terminal" corresponds to the communication device 3700 in FIG. 37, a "base station" corresponds to the communication device 3750 in FIG. 37, and a "server" corresponds to the server 3772 in FIG.

[0566] First, the terminal accesses the server via the base station (3801), and the server then confirms that the terminal has accessed (3802).

[0567] The terminal then receives the optical modulation signal and creates data related to the optical modulation signal to send to the server, but this data is not included in the optical modulation signal.

[0568] The terminal then transmits the "data relating to the optical modulation signal" to the base station for transmission to the server (3803).

[0569] The base station receives the "data relating to the optical modulation signal" transmitted by the terminal (3804).Then, the base station transmits this received data to the server.

[0570] The server then obtains the "data related to the optically modulated signal" transmitted by the base station (3806).The server then performs processes such as demodulation and error correction decoding on the data related to the optically modulated signal to obtain the data contained in the optically modulated signal (3807).The server then transmits the data contained in the optically modulated signal, i.e., the data obtained by processes such as demodulation, to the base station, and the base station transmits this data to the terminal (3808).

[0571] As a result, the terminal obtains received data in the form of an optically modulated signal.

[0572] By doing this, a terminal having a light receiving unit such as an image sensor and a communication function for connecting to a server can obtain received data of an optically modulated signal without adding a new signal processing unit. In other words, it is possible to obtain received data of an optically modulated signal while reducing the circuit scale and calculation scale of the terminal.

[0573] In this embodiment, the devices are referred to as terminals, base stations, and servers, but the devices are not limited to these names and the system can be configured with devices having communication functions. Also, the method for receiving an optically modulated signal described in this embodiment can be applied as the method for receiving an optically modulated signal described in this specification.

[0574] (Embodiment A2) In this embodiment, a moving image providing method using an optical modulation signal will be described.

[0575] FIG. 39A shows a first example of a system related to a moving image providing method using an optical modulation signal in this embodiment.

[0576] 39A, the system includes a communication system 3970 and a terminal 3980. The communication system 3970 includes a plurality of cameras 3971A, 3971B, . . . , 3971N, a server 3972, and a plurality of transmitting devices 3973A, 3973B, . . . , 3973N.

[0577] The cameras 3971A and the like capture images to generate image data.

[0578] Server 3972 stores image data generated by each of a plurality of cameras 3971A and the like.

[0579] The multiple transmitting devices 3973A etc. correspond one-to-one to the multiple cameras 3971A etc., and each of the multiple transmitting devices 3973A etc. transmits light as a visible light communication signal that includes information regarding communication for accessing a storage location in a server where image data generated by the camera corresponding to the transmitting device is stored.

[0580] For example, the information may include address information indicating a storage location where the image data is stored. The address information may be, for example, a URL. The address information may be included in a frame of the optical modulation signal as a "symbol containing access-related information."

[0581] For example, the information may include an encryption key used to encrypt communications for a terminal to access a storage location where image data is stored. The encryption key may be included, for example, as a "symbol related to the encryption key" in a frame of the optical modulation signal.

[0582] For example, the information may include an identifier of a wireless communication base station for a terminal to access a storage location where image data is stored. The identifier of the base station may be, for example, an SSID. The identifier of the base station may be included, for example, as an "SSID symbol" in a frame of the optical modulation signal.

[0583] For example, the information may include location information indicating the location where the image data was captured. The location information may be, for example, an identifier that can uniquely identify a seat in a stadium. The location information may be included in a frame of the optical modulation signal as a "symbol related to location information."

[0584] The terminal 3980 also includes a receiving device 3981 and a transmitting / receiving device 3982 .

[0585] The receiving device 3981 receives light containing information indicating the storage location of image data as a visible light communication signal.

[0586] The transmitting / receiving device 3982 receives the image data from the storage location indicated by the information received by the receiving device 3981 .

[0587] Next, the processing of the above system will be described.

[0588] FIG. 39B is a flow diagram showing an example of processing related to a moving image providing method using an optical modulation signal.

[0589] As shown in FIG. 39B, in step S3971, image data is generated by capturing images using a plurality of cameras 3971A and the like.

[0590] In step S3972, the image data generated by each of the plurality of cameras 3971A etc. is stored in the server 3972.

[0591] Each of the multiple transmitting devices 3973A, etc. transmits light as a visible light communication signal that includes information regarding communication for accessing a storage location in the server 3972 where image data generated by the camera corresponding to that transmitting device is stored.

[0592] In step S3981, light including information indicating the storage location of image data is received as a visible light communication signal.

[0593] In step S3982, the image data is received from the storage location indicated by the received information.

[0594] The system will be described in more detail below.

[0595] FIG. 39C shows a second example of a system related to the moving image providing method using an optical modulation signal in this embodiment.

[0596] This system is composed of a video providing system 3999 and terminals 3950_1 and 3950_2. The video providing system 3999 corresponds to the above-mentioned communication system.

[0597] The first camera 3902_1 is in communication with the server 3905, and the first camera 3902_1 transmits a signal 3903_1 including the first shooting data to the server 3905, and the server 3905 transmits a signal including the first data to the first camera 3902_1.

[0598] The second camera 3902_2 is in communication with the server 3905, and the second camera 3902_2 transmits a signal 3903_2 including second shooting data to the server 3905, and the server 3905 transmits a signal including the second data to the second camera 3902_2.

[0599] The third camera 3902_3 is in communication with the server 3905, and the third camera 3902_3 transmits a signal 3903_3 including the third shooting data to the server 3905, and the server 3905 transmits a signal including the third data to the third camera 3902_3.

[0600] At this time, the server 3905 provides the moving image or still image (corresponding to the first photographed data) taken by the first camera 3902_1 to the accessed terminal, etc. Similarly, the server 3905 provides the moving image or still image (corresponding to the second photographed data) taken by the second camera 3902_2 to the accessed terminal, etc. Then, the server 3905 provides the moving image or still image (corresponding to the third photographed data) taken by the third camera 3902_3 to the accessed terminal, etc.

[0601] The first transmitting device 3901_1 includes a transmitting device for transmitting (irradiating) an optical modulation signal, and the transmitted optical modulation signal includes information (for example, a URL (uniform resource locator)) of the access destination of the server 3905 for obtaining "video or still images (corresponding to the first photographed data) taken by the first camera 3902_1." Therefore, by receiving (receiving) the optical modulation signal transmitted (irradiated) by the first transmitting device 3901_1, the receiving terminal can obtain information of the access destination of the server 3905 and can obtain "video or still images (corresponding to the first photographed data) taken by the first camera 3902_1."

[0602] The second transmitting device 3901_2 includes a transmitting device for transmitting (irradiating) an optical modulation signal, and the transmitted optical modulation signal includes information (e.g., URL) of the access destination of the server 3905 for obtaining "video or still image (corresponding to second photographed data) taken by the second camera 3902_2." Therefore, by receiving (receiving) the optical modulation signal transmitted (irradiated) by the second transmitting device 3901_2, the receiving terminal can obtain information of the access destination of the server 3905 and can obtain "video or still image (corresponding to second photographed data) taken by the second camera 3902_2."

[0603] The third transmitting device 3901_3 includes a transmitting device for transmitting (irradiating) an optical modulation signal, and the transmitted optical modulation signal includes information (e.g., URL) of the access destination of the server 3905 for obtaining "video or still image (corresponding to third photographed data) taken by the third camera 3902_3." Therefore, by receiving (receiving) the optical modulation signal transmitted (irradiated) by the third transmitting device 3901_3, the receiving terminal can obtain information of the access destination of the server 3905 and can obtain "video or still image (corresponding to third photographed data) taken by the third camera 3902_3."

[0604] The video may also include voice and audio.

[0605] The first communication device 3911_1 is a device that communicates with the terminal 3950_1 or the terminal 3950_2, etc. The server 3905 outputs a signal 3906_1 (3909_1) including data, which is input to the first communication device 3911_1 via the network 3908_1. Then, the first communication device 3911_1 transmits a modulated signal 3912_1 including this data.

[0606] On the other hand, the first communication device 3911_1 receives a reception signal 3913_1 from the terminal, performs signal processing such as demodulation to obtain reception data, and outputs a signal 3910_1 including this data. The signal 3910_1 (3907_1) is input to the server 3905 via the network.

[0607] The second communication device 3911_2 is a device that communicates with the terminal 3950_1 or the terminal 3950_2. The server 3905 outputs a signal 3906_2 (3909_2) including data, which is input to the second communication device 3911_2 via the network 3908_2. Then, the second communication device 3911_2 transmits a modulated signal 3912_2 including this data.

[0608] On the other hand, the second communication device 3911_2 receives a reception signal 3913_2 from the terminal, performs signal processing such as demodulation to obtain reception data, and outputs a signal 3910_2 including this data. The signal 3910_2 (3907_2) is input to the server 3905 via the network.

[0609] The terminal 3950_1 includes a "receiving device 3951_1 that receives and demodulates an optically modulated signal" and a "transmitting / receiving device 3954_1 that communicates with the first communication device 3911_1 and the second communication device 3911_2."

[0610] The receiving device 3951_1 receives an optically modulated signal 3952_1 (transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, or the third transmitting device 3901_3), demodulates the optically modulated signal 3952_1, performs error correction decoding, and other processing, and obtains and outputs received data 3953_1.

[0611] The transmitting / receiving device 3954_1 receives the data 3955_1 and the (received) data 3953_1 as input, performs signal processing such as error correction coding and modulation, and generates and outputs a modulated signal 3957_1.

[0612] On the other hand, the transmission / reception device 3954_1 receives a modulated received signal 3958_1 transmitted by the first communication device 3911_1, the second communication device 3911_2, etc., and performs processing such as demodulation and error correction decoding to obtain and output received data 3956_1.

[0613] Similarly, the terminal 3950_2 includes a "receiving device 3951_2 that receives and demodulates an optically modulated signal" and a "transmitting / receiving device 3954_2 that communicates with the first communication device 3911_1 and the second communication device 3911_2."

[0614] The receiving device 3951_2 receives the optically modulated signal 3952_2 (transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, or the third transmitting device 3901_3), demodulates the optically modulated signal 3952_2, performs error correction decoding, and other processing, and obtains and outputs received data 3953_2.

[0615] The transmitting / receiving device 3954_2 receives the data 3955_2 and the (received) data 3953_2 as input, performs signal processing such as error correction coding and modulation, and generates and outputs a modulated signal 3957_2.

[0616] On the other hand, the transmission / reception device 3954_2 receives a modulated received signal 3958_2 transmitted by the first communication device 3911_1, the second communication device 3911_2, etc., performs processing such as demodulation and error correction decoding, and obtains and outputs received data 3956_2.

[0617] Next, a moving image providing method using the optical modulation signal of FIG. 39C and the operation of the system will be described with reference to FIGS. 40, 41, and 42. FIG.

[0618] Fig. 40 shows an example of a stadium scene. A soccer match is taking place on a field 4001. A goal is scored in an area 4002. In Fig. 40, the same numbers are used for devices corresponding to those in Fig. 39C.

[0619] It is assumed that a first camera 3902_1, a second camera 3902_2, a third camera 3902_3, and a fourth camera 3902_4 are installed to capture moving or still images of the state of the game on the field, the state of the spectators, etc. Note that the operations related to the first camera 3902_1, the second camera 3902_2, the third camera 3902_3, and the fourth camera 3902_4 have been explained using Fig. 39C, and therefore explanation thereof will be omitted.

[0620] A first transmitting device 3901_1, a second transmitting device 3901_2, a third transmitting device 3901_3, and a fourth transmitting device 3901_4 are installed in accordance with the first camera 3902_1, the second camera 3902_2, the third camera 3902_3, and the fourth camera 3902_4. Note that, as the operations related to the first transmitting device 3901_1, the second transmitting device 3901_2, the third transmitting device 3901_3, and the fourth transmitting device 3901_4 have been described using FIG. 39C, description thereof will be omitted. In this case, it is preferable that the first transmitting device 3901_1 is installed near the first camera 3902_1, the second transmitting device 3901_2 is installed near the second camera 3902_2, the third transmitting device 3901_3 is installed near the third camera 3902_3, and the fourth transmitting device 3901_4 is installed near the fourth camera 3902_4. Moreover, the first transmitting device 3901_1, the second transmitting device 3901_2, the third transmitting device 3901_3, and the fourth transmitting device 3901_4 may also serve as lighting devices for irradiating light onto the stadium field.

[0621] 40, first terminal 3950_1 and the user using first terminal 3950_1 are in positions as shown in Fig. 40, and it is highly likely that they had difficulty viewing the scoring scene that occurred in area 4002. Accordingly, it is assumed that the user using first terminal 3950_1 has a request to view a video or still image taken by a camera closer to area 4002 where the scoring scene occurred, that is, third camera 3902_3.

[0622] Therefore, it is assumed that the user performs an operation of pointing the light receiving unit of the receiving device 3951 of the first terminal 3950_1 toward the third camera 3902_3, whereby the first terminal 3905_1 receives the optical modulation signal transmitted (irradiated) by the third transmitting device 3901_3 located near the third camera 3902_3.

[0623] Starting from this operation, the first terminal 3905_1 obtains information on the moving image or still image taken by the third camera 3902_3, and the detailed operation will be described with reference to FIGS.

[0624] Fig. 41 shows an example of the operational flow of the k-th camera 3902_k, the k-th transmission device 3901_k, and the server 3905. In a scene like that shown in Fig. 40, k is 1, 2, 3, or 4. However, the number of cameras and transmission devices is not limited to four.

[0625] Also, in Figures 39C and 40, an example is described in which there is one device that transmits an optical modulation signal including information (e.g., a URL) on the server 3905 to access in order to obtain "video or still images (corresponding to the kth shooting data) captured by the kth camera 3902_k," but there may be multiple devices that transmit an optical modulation signal including information (e.g., a URL) on the server 3905 to access in order to obtain "video or still images (corresponding to the kth shooting data) captured by the kth camera 3902_k," and even if there are multiple devices, the implementation can be similar.

[0626] As shown in FIG. 41, it is assumed that the k-th camera 3902_k is capturing a moving image or a still image (4101).

[0627] Then, the k-th camera 3902_k transmits the captured data to the server 3905. Then, the k-th camera 3902_k transmits information on the access destination for viewing the video or still images stored in the server to the k-th transmission device 3901_k (4102).

[0628] Then, the k-th transmitting device 3901_k obtains information on the access destination for viewing the video or still image stored in the server, and transmits (irradiates) an optical modulation signal including this information (4103).

[0629] The server 3905 also stores the photographic data transmitted by the k-th camera 3902_k and distributes it (4104).

[0630] 41, it is stated that "the k-th camera 3902_k transmits to the k-th transmission device 3901_k information on the access destination for viewing the video or still images stored in the server," but this operation may not be performed and the k-th transmission device 3901_k may previously store "the k-th camera 3902_k information on the access destination for viewing the video or still images stored in the server." As another method, the operation "the k-th camera 3902_k transmits to the k-th transmission device 3901_k information on the access destination for viewing the video or still images stored in the server" is not limited to the timing shown in FIG. 41 and may be performed at any timing.

[0631] Figure 42 shows an example of the operation flow of the first terminal 3950_1, the third transmitting device 3902_3, and the first communication device 3911_1 when the first terminal 3950_1 is attempting to obtain information about a video or still image captured by the third camera 3902_3 in the state of Figure 40.

[0632] 42, the third transmitting device 3901_3 obtains information on an access destination for viewing “a moving image or a still image captured by the third camera 3902_3” stored in the server 3905. Then, the third transmitting device 3901_3 transmits (irradiates) an optical modulation signal including this information (4201).

[0633] Since the user of the first terminal 3950_1 wants to view video or still images taken from near the third camera 3902_3, the first terminal 3950_1 attempts to receive (receive) the optical modulation signal being irradiated from near the third camera 3902_3, that is, the optical modulation signal transmitted by the third transmitting device 3901_3, and receives the optical modulation signal (4202).

[0634] Then, the first terminal 3950_1 receives the optical modulation signal transmitted by the third transmitting device 3901_3 and obtains information on the access destination for obtaining video or still images captured by the third camera 3902_3, and the first terminal 3950_1 requests access to the server 3905 via the first communication device 3911_1 using the transmitting / receiving device 3954_1 (4203).

[0635] The first communication device 3911_1 receives the modulated signal 3957_1 transmitted by the transmitting / receiving device 3954_1 included in the first terminal 3950_1. Then, the first communication device 3911_1 learns that "the first terminal 3950_1 has requested data of moving images or still images taken by the third camera 3902_3," and accesses the server 3905 to obtain information on "the moving images or still images taken by the third camera 3902_3" (4204).

[0636] Then, the first communication device 3911_1 transmits a modulated signal 3912_1 including information on "moving or still images taken by the third camera 3902_3" (4205).

[0637] Then, the first terminal 3950_1 receives the modulated signal 3912_1 transmitted by the first communication device 3911_1 and obtains information on the "moving image or still image taken by the third camera 3902_3" (4206).

[0638] In explaining the scene in Figure 40, an example has been given in which there is one terminal, "first terminal 3950_1," but this is not limited to this; in other words, multiple terminals may access information about video or still images captured by, for example, third camera 3902_3.

[0639] Also, in FIG. 39C, an example is described in which there are two communication devices, a first communication device 3911_1 and a second communication device 3911_2, for accessing the server 3950, but this is not limited to this, and it may be that "one communication device exists" or "two or more communication devices exist."

[0640] By doing so, the user of the terminal can easily obtain the desired moving or still image data.

[0641] Next, an example of the frame structure of the modulated signal transmitted by each device in FIG. 39C will be described.

[0642] 43 shows an example of a frame configuration of an optical modulation signal transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in FIG. 39C, where the horizontal axis represents time. For example, the kth transmitting device 3901_k transmits a preamble 4301, a symbol including access-related information for video or still image data captured by the kth camera, and a data symbol 4303, in that order.

[0643] The preamble 4301 includes symbols for the receiving device of the other communication partner to synchronize time, etc., symbols for the receiving device of the other communication partner to perform signal detection, and control information symbols (e.g., information on the communication method, information on the modulation method, information on the error correction code) necessary for the receiving device of the other communication partner to demodulate each symbol.

[0644] Symbol 4302 containing access-related information for video or still image data captured by the kth camera is a symbol for notifying the receiving device, which is the communication partner, of information regarding the access destination for the video or still image data captured by the kth camera.

[0645] The data symbol 4303 is a symbol for the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 to transmit data to terminals such as the first terminal 3950_1 and the second terminal 3950_2.

[0646] In Fig. 43, symbols may exist in the frequency axis direction, i.e., in the carrier direction. Therefore, the modulated signal may be a multicarrier signal such as OFDM (Orthogonal Frequency Division Multiplexing), and symbols other than those shown in Fig. 43 may be included in the frame. Furthermore, the order in which symbols are transmitted is not limited to that shown in Fig. 43.

[0647] Figure 44 shows an example of a frame configuration different from that of Figure 43 for optically modulated signals transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C, where the horizontal axis represents time. Note that in Figure 44, components that operate in the same way as in Figure 43 are assigned the same numbers, and their explanations will be omitted.

[0648] 44 differs from FIG. 43 in that a symbol 4401 relating to an SSID is included in the frame. That is, the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 notify the terminals, such as the first terminal 3950_1 and the second terminal 3950_2, of the SSID of, for example, a wireless LAN that the terminals can access. This enables the terminals to easily and safely connect to the wireless LAN. Note that the details of the method of accessing a wireless LAN or the like using the symbol 4401 relating to an SSID have been described in the first to seventh embodiments, and therefore will not be described here.

[0649] This allows terminals such as the first terminal 3950_1 and the second terminal 3950_2 to access data of video or still images taken by the first camera 3902_1, data of video or still images taken by the second camera 3902_2, and data of video or still images taken by the third camera 3902_3 via an access point such as a wireless LAN.

[0650] In such a case, the first communication device 3911_1 and the second communication device 3911_2 in Fig. 39C are, for example, access points of a wireless LAN. Also, in Fig. 44, symbols may exist in the frequency direction, that is, in the carrier direction. Therefore, a modulated signal of a multicarrier method such as OFDM may be used, and symbols other than those shown in Fig. 44 may be included in the frame. Also, the order in which symbols are transmitted is not limited to that shown in Fig. 44.

[0651] Figure 45 shows an example of a frame configuration different from Figures 43 and 44 of the optically modulated signals transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C, where the horizontal axis represents time. Note that in Figure 45, components that operate in the same way as in Figures 43 and 44 are assigned the same numbers, and their explanation will be omitted.

[0652] 45 differs from FIGS. 43 and 44 in that a symbol 4501 relating to an encryption key is included in the frame. That is, the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 notify the terminals, such as the first terminal 3950_1 and the second terminal 3950_2, of the SSID of a wireless LAN that the terminals can access, and the encryption key of the wireless LAN. This enables the terminals to easily and safely connect to the wireless LAN. Note that the details of the method of accessing a wireless LAN or the like using the symbol 4401 relating to the SSID and the symbol 4501 relating to the encryption key have been described in the first to seventh embodiments, and therefore will not be described here.

[0653] This allows terminals such as the first terminal 3950_1 and the second terminal 3950_2 to access data of video or still images taken by the first camera 3902_1, data of video or still images taken by the second camera 3902_2, and data of video or still images taken by the third camera 3902_3 via an access point such as a wireless LAN.

[0654] In this case, the first communication device 3911_1 and the second communication device 3911_2 in Fig. 39C are, for example, access points of a wireless LAN. Also, in Fig. 45, symbols may exist in the frequency direction, that is, in the carrier direction. Therefore, a modulated signal of a multicarrier method such as OFDM may be used, and symbols other than those shown in Fig. 45 may be included in the frame. Also, the order in which symbols are transmitted is not limited to that shown in Fig. 45.

[0655] Figure 46 shows an example of a frame configuration different from those in Figures 43, 44, and 45 of the optically modulated signals transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C, where the horizontal axis represents time. Note that in Figure 46, components that operate in the same way as in Figures 43 and 45 are assigned the same numbers, and their explanation will be omitted.

[0656] 46 is characterized in that the frame does not include a symbol related to the SSID, but includes a symbol 4501 related to the encryption key. In this case, either of the following two methods may be applied.

[0657] (First method) There are two separate transmitters: one that transmits a frame containing a symbol 4401 related to the SSID, as in Fig. 44, and the other that transmits a frame containing a symbol 4501 related to the encryption key, as in Fig. 46. A terminal receives optically modulated signals from these two transmitters and can access a communication device such as a wireless LAN.

[0658] The terminal can then access data of video or still images taken by the first camera 3902_1, data of video or still images taken by the second camera 3902_2, and data of video or still images taken by the third camera 3902_3 via a communication device such as a wireless LAN.

[0659] Note that the symbol 4302 including the access-related information for the video or still image data captured by the k-th camera may not be included in either the frame of the frame configuration of FIG. 44 or the frame configuration of FIG.

[0660] This allows terminals such as the first terminal 3950_1 and the second terminal 3950_2 to access data of video or still images taken by the first camera 3902_1, data of video or still images taken by the second camera 3902_2, and data of video or still images taken by the third camera 3902_3 via an access point such as a wireless LAN.

[0661] In this case, the first communication device 3911_1 and the second communication device 3911_2 in Fig. 39C are, for example, access points of a wireless LAN. Also, in Fig. 46, symbols may exist in the frequency direction, that is, in the carrier direction. Therefore, a modulated signal of a multicarrier method such as OFDM may be used, and symbols other than those shown in Fig. 46 may be included in the frame. Also, the order in which symbols are transmitted is not limited to that shown in Fig. 46.

[0662] (Second method) Consider a state in which a terminal can obtain information about an access point such as a wireless LAN. In this case, it is assumed that the terminal receives an optical modulation signal having the frame configuration of FIG. 46 and obtains a symbol 4501 related to an encryption key. This enables the terminal to connect to an access point such as a wireless LAN. Therefore, terminals such as a first terminal 3950_1 and a second terminal 3950_2 can access data of moving images or still images taken by a first camera 3902_1, data of moving images or still images taken by a second camera 3902_2, and data of moving images or still images taken by a third camera 3902_3 via an access point such as a wireless LAN.

[0663] In this case, the first communication device 3911_1 and the second communication device 3911_2 in Fig. 39C are, for example, access points of a wireless LAN. Also, in Fig. 46, symbols may exist in the frequency direction, that is, in the carrier direction. Therefore, a modulated signal of a multicarrier method such as OFDM may be used, and symbols other than those shown in Fig. 46 may be included in the frame.

[0664] By implementing the above, the user can obtain video or still images taken at the user's desired position by simply pointing the terminal in the direction of the user's desired position, thereby achieving the effect of allowing the terminal to obtain video or still images taken at the user's desired position.

[0665] (Embodiment A3) In this embodiment, we will explain the frame structure of the optical modulated signal transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C described in embodiment A2, which is different from the frame structures shown in Figures 43 to 46.

[0666] Figure 47 shows an example of a frame configuration of an optically modulated signal transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C, where the horizontal axis represents time. The frame configuration in Figure 47 includes a symbol 4701 containing location information in addition to the symbols constituting the frame in Figure 43. For example, when the first transmitting device 3901_1 in Figure 39C transmits the frame configuration in Figure 47, the symbol 4701 containing location information includes information about the vicinity of the location of the first transmitting device 3901_1 or the first camera 3902_1. For example, it may be information about seats in a stadium.

[0667] In this way, the terminal can obtain information about the location where the video or still image about which the terminal is trying to obtain information was taken, and the terminal can determine whether the information is the desired video or still image.

[0668] Furthermore, in a stadium or the like, a terminal can obtain symbol 4701 containing the location information contained in Figure 47, thereby enabling a user using the terminal to easily find their seat.

[0669] In Fig. 47, symbols may exist in the frequency axis direction, i.e., in the carrier direction. Therefore, the modulated signal may be a multicarrier signal such as OFDM, and symbols other than those shown in Fig. 47 may be included in the frame. Furthermore, the order in which symbols are transmitted is not limited to that shown in Fig. 47.

[0670] Figure 48 shows an example of a frame configuration of an optically modulated signal transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C, with the horizontal axis representing time. The frame configuration in Figure 48 includes a symbol 4701 containing location information in addition to the symbols constituting the frame in Figure 44. For example, when the first transmitting device 3901_1 in Figure 39C transmits the frame configuration in Figure 48, the symbol 4701 containing location information includes information about the vicinity of the location of the first transmitting device 3901_1 or the first camera 3902_1. For example, it may be information about seats in a stadium.

[0671] In this way, the terminal can obtain information about the location where the video or still image about which the terminal is trying to obtain information was taken, and the terminal can determine whether the information is the desired video or still image.

[0672] Furthermore, in a stadium or the like, a terminal can obtain symbol 4701 containing the location information included in Figure 48, thereby enabling a user using the terminal to easily find their seat.

[0673] Figure 49 shows an example of a frame configuration of an optically modulated signal transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C, where the horizontal axis represents time. The frame configuration in Figure 49 includes a symbol 4701 containing position information in addition to the symbols constituting the frame in Figure 45. For example, when the first transmitting device 3901_1 in Figure 39C transmits the frame configuration in Figure 49, the symbol 4701 containing position information includes information about the vicinity of the location of the first transmitting device 3901_1 or the first camera 3902_1. For example, it may be information about seats in a stadium.

[0674] In this way, the terminal can obtain information about the location where the video or still image about which the terminal is trying to obtain information was taken, and the terminal can determine whether the information is the desired video or still image.

[0675] Furthermore, in a stadium or the like, a terminal can obtain symbol 4701 containing the location information included in Figure 49, thereby enabling a user using the terminal to easily find their seat.

[0676] Figure 50 shows an example of a frame configuration of an optically modulated signal transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3 in Figure 39C, where the horizontal axis represents time. The frame configuration in Figure 50 includes a symbol 4701 containing location information in addition to the symbols constituting the frame in Figure 46. For example, when the first transmitting device 3901_1 in Figure 39C transmits the frame configuration in Figure 50, the symbol 4701 containing location information includes information about the vicinity of the location of the first transmitting device 3901_1 or the first camera 3902_1. For example, it may be information about seats in a stadium.

[0677] In this way, the terminal can obtain information about the location where the video or still image about which the terminal is trying to obtain information was taken, and the terminal can determine whether the information is the desired video or still image.

[0678] Furthermore, in a stadium or the like, a terminal can obtain symbol 4701 containing the location information included in Figure 50, thereby enabling a user using the terminal to easily find their seat.

[0679] 39C may have a function of storing location information included in the symbol 4701 containing location information transmitted by the first transmitting device 3901_1, the second transmitting device 3901_2, and the third transmitting device 3901_3. This has the advantage that a user who owns the terminal can easily call up location information (seat information in the stadium) and can also know the access destination for obtaining a video or a still image together with the location information.

[0680] (Supplementary Note 3) In the embodiments described in this specification as "operations relating to a vehicle equipped with a communication device," it is possible to implement each embodiment in the same way by replacing "a vehicle equipped with a communication device" with "a robot equipped with a communication device," or "a vehicle equipped with a communication device," or "a movable household appliance (household electrical machinery and equipment) equipped with a communication device," or "a two-wheeled vehicle equipped with a communication device," or "a drone equipped with a communication device," or "an aircraft equipped with a communication device," or "a vehicle equipped with a communication device," or "an airship equipped with a communication device," or "a ship equipped with a communication device."

[0681] In addition, in the embodiment A2, for example, in FIG. 40, an example has been described in which the first terminal 3950_1 obtains any one of "video or image of the first camera 3902_1," "video or image of the second camera 3902_2," "video or image of the third camera 3902_3," and "video or image of the fourth camera 3902_4." However, for example, if a fifth transmission device 3901_3 is provided between the third transmission device 3901_3 and the fourth transmission device 3901_4, 901_5, and when first terminal 3950_1 obtains this optical modulation signal, a video or image estimated to have been taken near fifth transmitting device 3901_5 may be generated from a plurality of videos or images among "video or image of first camera 3902_1," "video or image of second camera 3902_2," "video or image of third camera 3902_3," and "video or image of fourth camera 3902_4," and provided to first terminal 3950_1. Note that the generation of this video or image is performed, for example, by server 3905 in Fig. 39C, and is provided to first terminal 3950_1 in the same manner as the video or image providing method described in embodiment A2.

[0682] The communication system 3970 in FIG. 39A of embodiment A2 may be mounted on a robot, a car, a vehicle, a (movable) home appliance (household electrical machinery and equipment), a motorcycle, a drone, an aircraft, a vehicle, an airship, a ship, or the like. Furthermore, as described above, if multiple cameras are mounted, a "video or image" from a "synthetic or virtual viewpoint" may be generated from videos or images acquired from the multiple cameras and provided to a terminal. In FIG. 39A, the "video or image" from a "synthetic or virtual viewpoint" is generated by, for example, server 3972. Although it is called a server, it may also be a signal processing unit.

[0683] Although the term "server" is used in this specification, the term is not limited to this and may also be a signal processing unit, personal computer, computer, tablet, arithmetic processing unit, CPU, GPU (Graphics Processing Unit), etc.

[0684] 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 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. Here, the software that realizes the system or device of each of the above embodiments is a program such as the following.

[0685] In other words, this program is a control method for a communication system, the communication system comprising a plurality of cameras, a server, and a plurality of transmitting devices each having a one-to-one correspondence with the plurality of cameras, the control method being executed to generate image data by capturing images using the plurality of cameras, the image data generated by each of the plurality of cameras being stored in the server, and each of the plurality of transmitting devices transmitting light as a visible light communication signal containing information regarding communication for accessing a storage location in the server where the image data generated by the camera corresponding to the transmitting device is stored.

[0686] The program also executes a control method for a terminal, which receives light containing information indicating a storage location of image data as a visible light communication signal, and receives the image data from the storage location indicated by the received information.

[0687] Although the communication system according to one or more aspects has been described based on the embodiments, the present invention is not limited to these embodiments. As long as it does not deviate from the spirit of the present invention, various modifications conceivable by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments may also be included within the scope of one or more aspects. [Industrial Applicability]

[0688] The present invention is useful in obtaining location information. [Explanation of symbols]

[0689] 3901_1, 3901_2, 3901_3, 3973A, 3973B, 3973N Transmitting device 3902_1, 3902_2, 3902_3, 3971A, 3971B, 3971N camera 3903_1, 3903_2, 3903_3, 3906_1, 3906_2, 3907_1, 3907_2, 3909_1, 3909_2, 3910_1, 3910_2 signal 3908_1, 3908_2 Network 3905, 3972 servers 3911_1, 3911_2 Communication equipment 3912_1, 3912_2, 3957_1, 3957_2 modulated signals 3913_1, 3913_2, 3958_1, 3958_2 received signals 3950_1, 3950_2 terminals 3951_1, 3951_2 receiving device 3952_1, 3952_2 Optical modulation signal 3953_1, 3953_2, 3956_1, 3956_2 Received data 3954_1, 3954_2 Transmitter / Receiver 3955_1, 3955_2 data 3970 Communication Systems 3999 Video Provision System

Claims

1. an optical communication device that receives received optical signals from a plurality of optical signals transmitted by a plurality of transmitting devices, the plurality of optical signals having intensities modulated by transmission data including access information for accessing image data captured by a camera corresponding to the transmitting device that transmits the optical signals; a wireless communication device that receives the image data based on the access information obtained from the optical signal received by the optical communication device, a user directs a light receiving unit toward the optical signal corresponding to the camera from which the user wants to view the image data, among the plurality of optical signals, thereby acquiring image data corresponding to the camera; Terminal.

2. The access information includes address information indicating a storage location where the image data is stored. The terminal according to claim 1 .

3. The access information includes an encryption key used to encrypt communication for a terminal to access a storage location where the image data is stored. The terminal according to claim 1 .

4. The access information includes an identifier of a wireless communication base station for a terminal to access a storage location where the image data is stored. The terminal according to claim 1 .

5. The access information includes location information indicating the location where the image data was captured. The terminal according to claim 1 .

6. A method executed by a terminal, comprising: A received optical signal is received from among a plurality of optical signals transmitted by a plurality of transmitting devices, and the plurality of optical signals are photographed by a camera corresponding to the transmitting device that transmits the optical signal. the intensity is modulated by transmission data including access information for accessing the stored image data, receiving the image data based on the access information obtained from the received optical signal; the user directs a light receiving unit of the terminal toward the optical signal corresponding to the camera from which the user wants to view the image data, among the plurality of optical signals, thereby acquiring image data corresponding to the camera; method.

7. A program that causes a computer to execute the method according to claim 6.

Images