WO2006077968A1

WO2006077968A1 - Optical communication system

Info

Publication number: WO2006077968A1
Application number: PCT/JP2006/300854
Authority: WO
Inventors: Hidemitsu Sugiyama; Shinichiro Haruyama; Masao Nakagawa; Takehiko Yamagichi; Takemi Arita
Original assignee: Nakagawa Laboratories, Inc.
Priority date: 2005-01-21
Filing date: 2006-01-20
Publication date: 2006-07-27
Also published as: TW200631333A; JP2006203669A

Abstract

[PROBLEMS] To provide an optical communication system wherein modulated lights emitted from a plurality of light sources are received to perform a transmission of information, and a multiple access system wherein the transmission can be performed without establishing any synchronization of the light sources and wherein the arrangement is simple and can be made at a low cost. [MEANS FOR SOLVING PROBLEMS] In a transmitting end apparatus (1), a transmission timing control part (14) decides, based on a random number generated by a random number generating part (13), a transmission timing and notifies it to a transmission processing part (12), which then modulates information by use of a given modulation scheme. The modulated light is then emitted from a light source (11) at a random timing under control of the transmission timing control part (14). Similarly, information is transmitted from a plurality of other transmitting end apparatuses (1) at random timings. In a receiving end apparatus (2), a light receiving part (21) receives the modulated lights from the transmitting end apparatuses (1) and converts them to electric signals, which are then sent to a reception processing part (22) where the information is demodulated. If a collision determining part (23) detects any signal collisions, it outputs no data. Only if it detects no signal collisions, it outputs the information.

Description

Optical communication system

Technical field

[0001] The present invention relates to an optical communication system using an optical signal emitted into space as a communication medium.

Background art

[0002] With the development of LDs (Laser Diodes) and LEDs (Light Emitting Diodes), methods have been proposed that use visible light generated by luminaires as a communication medium. For example, it is described in Patent Documents 1 and 2. Since lighting fixtures exist everywhere, if illumination light can be used for communication, wireless communication can be realized simply by adding a new function to the lighting fixture.

[0003] FIG. 7 is an explanatory diagram of an outline of a communication method using a lighting fixture as a transmitter. In the figure, reference numerals 31 to 33 denote lighting fixtures and 34 denotes a receiver. In this example, lighting fixtures 31 to 33 illuminate the room. The visible light emitted from the luminaires 31 to 33 is modulated according to information. The modulated visible light is received by the receiver 34 and demodulated to receive information.

However, as shown in FIG. 7, there are generally many lighting fixtures, and in many cases, the lighting fixtures are arranged so that light from a plurality of lighting fixtures overlap. For this reason, if these luminaires are used as transmitters and each transmitter transmits data without permission, the signals will interfere with each other and the signals will collide. There is a problem. For example, in FIG. 7, a plurality of modulated visible lights emitted from the respective lighting fixtures 31 to 33 are incident on the receiver 34. Therefore, signal interference and collision occur.

In order to solve this problem, it is necessary to consider a multiple access method. In conventional wireless communication using radio waves, research on multiple access has been conducted for many years. However, there is still research on multiple access in optical communication. When communicating using light emitted into space, such as when using a lighting fixture as a transmitter Specifically, a multiple access method that takes the following points into consideration is required.

, A method that does not consider synchronization between transmitting devices (lighting fixtures, etc.).

• A simple and inexpensive method that adds a transmission function to the transmitting device (lighting equipment, etc.).

[0006] The fact that synchronization between transmitters is not taken into account is that, for example, as shown in FIG. 7, when a lighting fixture is used as a transmitter, there are many lighting fixtures. This is because it is difficult to synchronize the lighting fixtures. In addition, the simple and inexpensive method assumes that a large number of transmission side devices are used, assuming that lighting equipment is used as the transmission side device. For this reason. In the future, it may be possible to connect the luminaire to the network for two-way communication, but at the present stage, information is mainly transmitted using only the luminaire power downlink. Therefore, for the time being, there is a need for a simple and inexpensive multiple access method for downlink only.

[0007] The multiple access methods that have been studied in the past are as follows.

• TDMA (Time Division Multiple Access)

In this method, time slots divided in time are allocated to each transmitter and transmitted. However, since it is necessary to synchronize with each other, it is difficult to realize in the case of only the downlink using lighting equipment.

• SDMA (space division multiple access)

This is a method of spatially dividing a signal on the receiver side using an image sensor or the like. There is a problem that the receiver becomes expensive.

• CSMA (Carrier Sense Multiple Access)

This is a method of detecting a time when a channel is empty and transmitting without detecting transmission while other transmitters transmit by detecting a carrier wave. Since it is necessary to receive a signal on the transmitter side, it is impossible to adopt this method when considering only downlink communication. • WDMA (wavelength division multiple access)

In this method, the wavelength of light is divided and assigned to each transmitter. It is often used in optical fibers, etc. and may be realized with visible light communication.

• FDMA (frequency division multiple access) In this method, the subcarrier frequency band is divided and assigned. It can be realized relatively easily by visible light communication.

. CDMA (Code Division Multiple Access)

In this method, a special code is assigned to each transmitter, and the code is divided and transmitted. This is also considered feasible.

[0008] The above study capabilities WDMA, FDMA, and CDMA are considered to be promising as multiple access that can be realized only in the downlink. However, problems arise even when these multiple access methods are adopted. Here, since only downlink communication is performed, the wavelength “subcarrier” code cannot be dynamically assigned as in the case of wireless communication, and is fixedly assigned to each transmitter. If the same wavelength / subcarrier 'code is assigned to neighboring transmitters, interference and collision between signals will still occur, making it impossible to realize multiple access.

[0009] Therefore, when installing a transmitter using the conventional multiple access method, the user needs to devise a contrivance, "Do not install transmitters of the same wavelength, subcarrier, and code nearby." is there. This is a very complicated operation for the installer and the user, and reduces the user interface. For practical use, there is a need for a multiple access method that can prevent interference and collision even when the same transmitter is installed in all locations.

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-147063

Patent Document 2: JP 2004-185359 A

Disclosure of the invention

Problems to be solved by the invention

[0011] The present invention has been made in view of the above-described circumstances, and is an optical communication system that transmits information by receiving modulated optical signals generated by a plurality of light sources, respectively. It is an object to provide a multiple access method that can transmit without synchronizing with a light source of the same type and can be configured at a low cost with a simple force.

Means for solving the problem

The invention described in claim 1 of the present application is an optical communication system for transmitting information by emitting a modulated optical signal, and a light source that emits light by light emission, and modulating given information. Said Transmitting means for driving the light source and transmitting the information by emitting modulated light to the light source, random number generating means for generating random numbers, and timing control means for controlling transmission timing according to the random numbers generated by the random number generating means And the transmission means transmits the information at a transmission timing controlled by the timing control means.

[0013] The invention according to claim 2 of the present application is a configuration on the receiving side that receives the light emitted by the invention according to claim 1, and modulated light modulated in accordance with a plurality of light source power information is arbitrary. A light receiving means for receiving modulated light and converting it into an electric signal, a receiving means for demodulating the electric signal converted by the light receiving means and receiving information, and a light receiving method. And a collision determination means for detecting that signals from a plurality of light sources collide with each other based on the electric signal converted by the means or the signal demodulated by the receiving means, and only signals that have not collided are detected. The extracted information is used as received information.

The invention according to claim 3 of the present application is an optical communication system for transmitting information by emitting a modulated optical signal, and a light source that emits light by light emission, and modulates given information. A transmitter that transmits the information by driving the light source and causing the light source to emit modulated light, a random number generator that generates a random number, and a subcarrier frequency that controls a subcarrier frequency according to the random number generated by the random number generator. Carrier frequency control means is provided, and the transmission means transmits the information using a subcarrier frequency controlled by the subcarrier frequency control means.

[0015] The invention according to claim 4 of the present application is a configuration on the receiving side that receives the light emitted by the invention according to claim 3, and has a predetermined frequency band modulated in accordance with a plurality of light source power information. Is an optical communication system that emits modulated light at an arbitrary subcarrier frequency. Light receiving means that receives the modulated light and converts it into an electrical signal, and V transmits the electrical signal converted by the light receiving means. For each of the subcarrier frequencies that can be taken by the receiver, the receiving means that demodulates the signals, and signals of a plurality of light source powers collide with each subcarrier frequency based on the signals demodulated by the receiving means. It has a collision determination means for detecting the fact that the signal has been detected, and extracts only signals that do not collide as reception information.

[0016] The invention according to claim 5 of the present application is a light for transmitting information by emitting a modulated optical signal. A communication system that emits light by light emission, a transmission unit that modulates given information, drives the light source, emits modulated light to the light source and transmits the information, and generates a random number Random number generating means and spreading code control means for determining a spreading code at the time of transmission according to the random number generated by the random number generating means, wherein the transmitting means uses the spreading code determined by the spreading code control means The information is transmitted.

[0017] The invention described in claim 6 of the present application is a configuration on the receiving side that receives the light emitted by the invention described in claim 5, and an arbitrary diffusion code modulated in accordance with a plurality of light source power information. Is an optical communication system in which modulated light is emitted by a signal, and the light receiving means that receives the modulated light and converts it into an electrical signal, and the electrical signal converted by the light receiving means are separated into respective spreading codes. A receiving means for demodulating and a collision judging means for detecting that a signal of a plurality of light source powers collides with each spread code based on the signal demodulated by the receiving means, and there is no collision. It is characterized by extracting only the signal and using it as received information.

The invention according to claim 7 of the present application is an optical communication method for transmitting information by emitting a modulated optical signal, and is provided with a light source that emits modulated light in a specified wavelength range. And transmitting the information by modulating the information and driving the light source to emit modulated light to the light source, random number generating means for generating random numbers, and according to the random numbers generated by the random number generating means A transmission wavelength control unit that determines a wavelength range in which the light source emits light, wherein the light source emits modulated light from the transmission unit in a wavelength range determined by the transmission wavelength control unit; .

The invention described in claim 8 of the present application is a configuration on the receiving side that receives the light emitted by the invention described in claim 7, and has an arbitrary wavelength range modulated in accordance with a plurality of light source power information. An optical communication system that emits an optical signal of a light receiving device that receives light in each wavelength region and converts it into an electrical signal, and an electrical signal corresponding to each wavelength region converted by the light receiving device. Receiving means for demodulating each of them, and collision judging means for detecting that signals from a plurality of light sources collide with each wavelength region based on the signals demodulated by the receiving means, Extract only a bad signal when there is a collision and use it as received information. It is characterized by.

The invention's effect

[0020] According to the present invention, an optical signal modulated by information is emitted while changing a transmission timing, a subcarrier frequency, a spread code, and a wavelength range according to random numbers, so that the optical signals modulated from a plurality of light sources are independent. Even if it is released, it is possible to receive information just by extracting the! In this way, it is possible to transmit information only in one direction (downlink) from the transmission side to the reception side without synchronizing the transmission side and the reception side. There is an effect that can be.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, 1 is a transmission side device, 2 is a reception side device, 11 is a light source, 12 is a transmission processing unit, 13 is a random number generation unit, 14 is a transmission timing control unit, 21 is a light receiving unit, and 22 is a reception processing unit. , 23 is a collision determination unit. In the first embodiment, an example in which the transmission timing is randomly changed will be described.

[0022] The transmission side device 1 includes a light source 11, a transmission processing unit 12, a random number generation unit 13, a transmission timing control unit 14, and the like. The light source 11 emits light such as visible light and infrared light. At this time, the optical signal that is modulated and driven by the transmission processing unit 12 can be emitted. For this purpose, a light source with sufficiently fast response characteristics is used. For example, the power with which semiconductor light-emitting elements such as LEDs and LDs are optimal is not limited to this.

The transmission processing unit 12 modulates given information to drive the light source 11 and causes the light source 11 to emit modulated light to transmit information. The modulation method is arbitrary and only needs to match the demodulation method of the receiving device. The timing of transmitting information is controlled by the transmission timing control unit 14. In addition to the given information, various information such as an error detection code or an ID of the transmission side device 1 may be added as information to be transmitted.

The random number generation unit 13 generates a random number and passes it to the transmission timing control unit 14.

The transmission timing control unit 14 controls the timing at which the transmission processing unit 12 transmits information according to the random number generated by the random number generation unit 13.

[0026] The receiving-side device 2 includes a light receiving unit 21, a reception processing unit 22, a collision determination unit 23, and the like. The light receiving unit 21 receives light coming from the outside, for example, an optical signal from the transmission side device 1. Is received and converted into an electrical signal. As the light receiving unit 21, various light receiving elements such as PD (Photo Diode) can be used.

[0027] The reception processing unit 22 demodulates the electrical signal converted by the light receiving unit 21 and receives information.

[0028] The collision determination unit 23 determines whether or not a plurality of light source power signals collide based on the electrical signal converted by the light receiving unit 21 or the signal demodulated by the reception processing unit 22. Then, only signals that do not collide are extracted and output as received information. Judgment of signal collision includes various checks such as whether or not the reception processing unit 22 has been demodulated normally, checking the error detection code of the demodulated signal, and the waveform of the electrical signal output from the light receiving unit 21. The method can be applied.

[0029] Next, an outline of operation in the first exemplary embodiment of the present invention will be described. In the transmission side device 1, the transmission processing unit 12 modulates the information to be transmitted by an arbitrary modulation method. In addition, the transmission timing control unit 14 determines the timing to be transmitted based on the random number generated by the random number generation unit 13 and transmits it to the transmission processing unit 12. The random timing signal generated by the transmission processing unit 12 is emitted as modulated light from the light source 11, and information is transmitted.

[0030] There may be a plurality of such transmission-side devices 1, and each transmission-side device 1 performs the above-described transmission operation independently. That is, the transmission side device 1 transmits information by modulated light at random timing.

In the reception side device 2, the modulated light emitted from one or a plurality of transmission side devices 1 is received by the light receiving unit 21 and converted into an electrical signal, and the reception processing unit 22 demodulates information from the electrical signal. . The collision determination unit 23 detects signal collision from the demodulated information using, for example, an error detection code. If it is determined that there is a collision, no data is output, and information is output only when it is determined that there is no collision.

FIG. 2 is a conceptual diagram of transmission / reception timing in the first embodiment of the present invention. As described above, in the first embodiment of the present invention, each transmitting-side apparatus 1 independently transmits information using modulated light at random timing. In FIG. 2, the transmitting side device A and the transmitting side device B transmit information independently at random timing. The receiving side device 2 receives the modulated light emitted from the respective transmitting side devices A and B in this way without distinction. Then, the light emitted from the transmitting device A and the transmitting device B The timing at which the emitted light is simultaneously received is generated. This case is described as “collision” in FIG. In this way, when light from multiple transmitting side devices A and B overlaps and is received, the power that cannot be demodulated even if it is simply demodulated, or the transmitted side device A or transmitting side device B is also transmitted. Cannot be restored accurately. For this reason, the collision determination unit 23 detects such a case and does not output incorrect information.

[0033] If the timing at which information is transmitted from each transmitting side device 1 is deviated, the information can be received without being influenced by the light of other transmitting side devices ("Reception" in FIG. 2). Success "). In this case, the collision determination unit 23 does not detect a collision, and the information demodulated by the reception processing unit 22 may be output.

[0034] In this manner, each transmitting-side device 1 can transmit information with a simple configuration without having to synchronize between transmitting-side devices by simply transmitting information with modulated light at random timing. It can be performed. The receiving side device 2 also receives the modulated light emitted from each transmitting side device 1 and detects the presence or absence of a collision. The information according to can be received reliably. Further, in this method, since there is no need to synchronize between the transmission side device 1 and the reception side device 2, there is no need to transmit information from the reception side device 2 to the transmission side device 1. It enables information transmission by configuration.

[0035] When a collision of signals is detected by the collision determination unit 23, information transmitted from the transmission side devices A and B at that time is not received. However, for example, if the same information is repeatedly transmitted from the transmission side devices A and B, the probability that the information can be received is greatly improved. When communicating using light, since the propagation range is narrow due to the straightness of light, it is unlikely that a large number of transmitting device power modulated light will be received.For example, information can be transmitted reliably even several times. it can.

[0036] Further, as shown in FIG. 2, even when the signals are received without collision, the information transmitted from the transmission side device A and the transmission side device B is received irregularly. Become. For example, it is possible to specify the transmitting side device or the information from the ID in the received information, etc., and classify each information after reception.

[0037] In the example shown in FIG. 2, the signals from the transmission side device A and the transmission side device B collide. In some cases, it was treated as not being output. However, the present invention is not limited to this, and when all of the modulated light from a plurality of transmission side devices can be separated, they may be separated and demodulated. For example, if there is a difference in the intensity of the modulated light coming from the transmitting side devices A and B, the information can be demodulated even with strong light component power.

FIG. 3 is a block diagram showing a second embodiment of the present invention. In the figure, the same parts as those in FIG. 15 is a subcarrier frequency control unit. In the second embodiment, an example is shown in which a subcarrier frequency is changed randomly and an optical signal modulated according to information is transmitted.

The subcarrier frequency control unit 15 of the transmission side device 1 controls the subcarrier frequency when transmitting the optical signal according to the random number generated by the random number generation unit 13. The transmission processing unit 12 uses the subcarrier frequency controlled by the subcarrier frequency control unit 15 to emit an optical signal modulated according to the information from the light source 11 and transmits the information.

[0040] The reception processing unit 22 of the reception-side device 2 demodulates from the electric signal output from the light-receiving unit 21 for each of all the subcarrier frequencies that can be obtained by the transmission-side device 1. The collision determination unit 23 determines whether there is a collision with respect to the information received by the reception processing unit 22 for each subcarrier frequency. If there is no collision, the received information should be output.

[0041] Since the subcarrier frequency used by the transmission side device 1 is a part of the subcarrier frequencies that can be taken, even if reception processing is performed for all the subcarrier frequencies that can be taken by the reception processing unit 22, Only some subcarrier frequency forces can receive information. Therefore, the collision determination unit 23 may be configured to determine whether or not there is a collision with respect to the information received by the reception processing unit 22. Further, information to be output is information that can be received by the reception processing unit 22 and that has been determined to have been collided by the collision determination unit 23.

Next, an outline of the operation in the second embodiment of the present invention will be described. In the transmission side device 1, the transmission processing unit 12 modulates the information to be transmitted by an arbitrary modulation method. In addition, the subcarrier frequency control unit 15 determines a subcarrier frequency to be used based on the random number generated by the random number generation unit 13 and transmits it to the transmission processing unit 12. The transmission processing unit 12 sends the modulated information to the light source 11 using the subcarrier frequency determined by the subcarrier frequency control unit 15. Emitted from the light source 11 as modulated light. In this way, the subcarrier frequency is randomly changed, and information is transmitted using the subcarrier frequency.

[0043] In the reception side device 2, the modulated light emitted from one or a plurality of transmission side devices 1 is received by the light receiving unit 21 and converted into an electrical signal, and the reception processing unit 22 converts each of the sub signals from the electrical signal. Information is demodulated and received for each carrier frequency. The collision determination unit 23 detects signal collision from the demodulated information using, for example, an error detection code. When it is determined that there is a collision, no data is output, and only when it is determined that there is no collision, information is output.

[0044] When there are a plurality of transmission-side devices 1, each transmission-side device 1 independently selects and uses a subcarrier frequency in a random manner, and modulates and transmits information as an optical signal. If the subcarrier frequencies used by the respective transmission-side devices 1 are different, information can be received without being affected by the light of other transmission-side devices. In this case, the collision determination unit 23 does not detect the collision, and the information demodulated by the reception processing unit 22 for each subcarrier frequency may be output.

However, when one or a plurality of transmission side devices 1 select and use the same subcarrier frequency and transmit information, information transmitted using the subcarrier frequency collides. In this case, the collision determination unit 23 detects the collision and does not output the information. At this time, the information transmitted using the same subcarrier frequency is not received by the receiving side device 2. However, for example, if the same information is retransmitted a plurality of times, the receiving side device 1 can almost certainly receive the information. Device 2 can receive information. Also, even from information from the same transmitting device 1, the subcarrier frequency used from time to time is different. For example, after receiving, it is only necessary to identify the transmitting side device 1 or information that has transmitted ID and other information in the information.

In this way, each transmitting side apparatus 1 does not need to synchronize between transmitting side apparatuses by simply selecting a subcarrier frequency at random and transmitting information by modulated light. Therefore, the transmission-side device 1 can be realized with a simple configuration. Also, the receiving side device 2 can be realized with a simple configuration by receiving information transmitted at each subcarrier frequency and detecting the presence or absence of a collision. Further, since there is no need to synchronize between the transmission side device 1 and the reception side device 2, information is transmitted from the reception side device 2 to the transmission side device 1. It is possible to transmit information with a simpler configuration that is not necessary.

[0047] Note that even when a plurality of transmission-side devices 1 use the same subcarrier frequency, the reception-side device 2 may receive each information as long as it can be distinguished. For example, if the signal strength is different, the signal strength is strong and only the information may be received separately.

FIG. 4 is a block diagram showing a third embodiment of the present invention. In the figure, the same parts as those in FIG. Reference numeral 16 denotes a spreading code control unit. In the third embodiment, an example in which a spread code is randomly changed and an optical signal modulated according to information is transmitted will be described.

[0049] The spreading code control unit 16 of the transmission side device 1 controls the spreading code when transmitting the optical signal according to the random number generated by the random number generating unit 13. The transmission processing unit 12 uses the spreading code controlled by the spreading code control unit 16 to emit an optical signal modulated according to the information from the light source 11 and transmits the information.

[0050] The reception processing unit 22 of the reception side device 2 demodulates each of the spread codes that can be taken by the transmission side device 1 from the electrical signal output from the light receiving unit 21, and receives information. The collision determination unit 23 determines whether or not the information received for each spreading code by the reception processing unit 22 is a collision. If there is no collision, the received information should be output.

[0051] Note that since the spreading code used by the transmission-side apparatus 1 is a part of the possible spreading codes, a part of the spreading codes that can be taken by the reception processing unit 22 may be partially received. Only the information corresponding to the spread code can be received. Therefore, the collision determination unit 23 may be configured to determine whether or not there is a collision for the information received by the reception processing unit 22. Also, information to be output is information that can be received by the reception processing unit 22 and has been determined to have been collided by the collision determination unit 23.

Next, an outline of the operation in the third embodiment of the present invention will be described. In the transmission side device 1, the transmission processing unit 12 modulates the information to be transmitted by an arbitrary modulation method. Further, the spreading code control unit 16 determines the spreading code to be used based on the random number generated by the random number generating unit 13 and transmits it to the transmission processing unit 12. The transmission processing unit 12 causes the light source 11 to emit modulated information as modulated light using the spreading code determined by the spreading code control unit 16. this In this way, information is transmitted using a randomly selected spreading code.

In the reception side device 2, the modulated light emitted from one or a plurality of transmission side devices 1 is received by the light receiving unit 21 and converted into electrical signals, and the reception processing unit 22 converts each of the electrical signals from the electrical signals. Information is demodulated and received for each code. The collision determination unit 23 detects signal collision from the demodulated information using, for example, an error detection code. If it is determined that there is a collision, no data is output, and information is output only when it is determined that there is no collision.

[0054] When there are a plurality of transmission-side devices 1, each transmission-side device 1 independently selects and uses a spreading code, modulates information, and transmits the modulated optical signal as an optical signal. If the spreading codes used by the respective transmission-side devices 1 are different, information can be received without being affected by light from other transmission-side devices. In this case, the collision determination unit 23 does not detect the collision, and the information demodulated for each spreading code by the reception processing unit 22 may be output.

[0055] However, when one or a plurality of transmission-side apparatuses 1 select and use the same spreading code and transmit information, information transmitted using the spreading code collides. In this case, the collision determination unit 23 detects a collision and does not output this information. At this time, the information transmitted using the same spreading code is not received by the receiving side device 2. For example, if the transmitting side device 1 retransmits the same information a plurality of times, the receiving side device 2 almost certainly. Can receive information. In addition, the spread code used from time to time differs even for information from the same transmitting device 1. For example, after receiving, specify the ID in the information, etc.

[0056] In this way, it is not necessary to synchronize between the transmitting side devices, which simply needs to select a spreading code at random and transmit information using modulated light. Therefore, the transmission-side device 1 can be realized with a simple configuration. The receiving side device 2 can also be realized with a simple configuration by receiving information transmitted using each spreading code and detecting the presence or absence of a collision. Furthermore, since there is no need to synchronize between the transmission side device 1 and the reception side device 2, there is no need to transmit information from the reception side device 2 to the transmission side device 1, and information with a simpler configuration. Transmission is possible.

FIG. 5 is a block diagram showing a fourth embodiment of the present invention. In the figure, the same part as in Figure 1 Minutes may be denoted by the same reference numerals and redundant description may be omitted. Reference numeral 17 denotes a transmission wavelength control unit, 18 denotes a light source selector, 19 denotes a light source, and 24 denotes a light receiving element. In the fourth embodiment, an example in which the wavelength of an optical signal modulated according to information is randomly changed and transmitted is shown.

[0058] The light source 11 of the transmission-side device 1 can emit light in a wavelength region designated by an external force. For example, when using LD or LED, the emission wavelength cannot be changed from the outside. Therefore, in this example, a plurality of light emission sources 19 having different emission wavelengths are prepared, and the light emission source 19 to be emitted is selected by the light emission source selector 18 in accordance with the wavelength range designated from the outside.

The transmission wavelength control unit 17 controls the transmission wavelength range when transmitting an optical signal according to the random number generated by the random number generation unit 13. The transmission wavelength control unit 17 designates the determined transmission wavelength range to the light source selector 18 of the light source 11.

[0060] The light receiving unit 21 of the receiving side device 2 includes a plurality of light receiving elements 24 in order to receive light having a plurality of wavelengths. Any structure that can identify a color, for example, may be used as long as the wavelength is in the visible light range.

The reception processing unit 22 demodulates each of the wavelength ranges that can be obtained by the transmission side device 1 from the electrical signal output from the light receiving unit 21, and receives information. The collision determination unit 23 determines whether or not each collision is based on the information received by the reception processing unit 22 in each wavelength region. If there is no collision, the received information should be output.

[0062] Since the wavelength range used by the transmission side device 1 is a part of the possible wavelength range, even if reception processing is performed for all possible wavelength ranges in the reception processing unit 22, some of the wavelength ranges may be used. Only information corresponding to the wavelength range can be received. Therefore, the collision determination unit 23 may be configured to determine whether or not there is a collision with respect to the information received by the reception processing unit 22. Also, the information to be output is information that can be received by the reception processing unit 22 and that has been determined to have collided with! /, N! / By the collision determination unit 23.

Next, an outline of the operation in the fourth embodiment of the present invention will be described. In the transmission side device 1, the transmission processing unit 12 modulates the information to be transmitted by an arbitrary modulation method. Ma The transmission wavelength control unit 17 determines the transmission wavelength range to be used based on the random number generated by the random number generation unit 13 and transmits it to the light source selector 18 of the light source 11. The light source selector 18 of the light source 11 selects the light source 19 that emits light in the transmission wavelength range determined by the transmission wavelength control unit 17, and sends the information modulated by the transmission processing unit 12 to the light source 19. Then, the light source 19 emits modulated light. In this way, information is transmitted using light in a randomly selected wavelength range.

In the reception side device 2, the modulated light emitted from one or a plurality of transmission side devices 1 is received by the light receiving element 24 of the light receiving unit 21, converted into an electrical signal, and passed to the reception processing unit 22. The reception processing unit 22 also demodulates the electric signal power for each wavelength region and receives information. A collision determination unit 23 detects a signal collision from the demodulated information using, for example, an error detection code. When it is determined that there is a collision, no data is output. Only when it is determined that there is no collision, information is output.

[0065] When there are a plurality of transmission-side devices 1, each transmission-side device 1 independently selects and uses a wavelength range at random, modulates information, and transmits the optical signal as an optical signal. If the wavelength ranges used by the respective transmission-side devices 1 are different, information can be received without being affected by light from other transmission-side devices. In this case, the collision determination unit 23 does not detect the collision, and the information demodulated for each transmission wavelength by the reception processing unit 22 may be output.

However, when one or a plurality of transmission-side devices 1 select and use the same wavelength band and transmit information, information transmitted using the wavelength band collides. In this case, the collision determination unit 23 detects a collision and does not output the information. At this time, the information transmitted using the same wavelength band is not received by the receiving-side apparatus 2, but for example, if the same information is transmitted by the transmitting-side apparatus 1 and retransmitted a plurality of times, it is almost certain. The receiving side device 2 can receive information. In addition, even the information from the same transmission-side device 1 changes the wavelength range used from time to time. For example, after receiving, specify the sending device 1 or information that was sent from the ID in the information.

[0067] In this way, it is not necessary to synchronize between the transmission side devices, which simply needs to select the wavelength range of light at each transmission side device 1 and transmit information by using modulated light. Follow Thus, the transmission side device 1 can be realized with a simple configuration. The receiving side device 2 can also be realized with a simple configuration by receiving information transmitted using each wavelength band and detecting the presence or absence of a collision. Furthermore, since there is no need to synchronize between the transmission side device 1 and the reception side device 2, there is no need to transmit information from the reception side device 2 to the transmission side device 1, and information with a simpler configuration. Transmission is possible.

[0068] Note that even when a plurality of transmission-side devices 1 use the same wavelength band, respective information may be received as long as the reception-side device 2 can distinguish them. For example, if the signal strength is different, the signal strength may be received separately.

[0069] FIG. 6 is a block diagram showing a modification of the fourth embodiment of the present invention. The reference numerals in the figure are the same as those in FIG. In the example shown in FIG. 5, a configuration is shown in which a plurality of light emitting sources 19 having different emission wavelengths are provided, and the light source selector 18 selects them. However, the present invention is not limited to this, and when the light source itself can control the wavelength from the outside, as shown in FIG. 6, the light source 11 emits light in the wavelength range selected and designated by the transmission wavelength control unit 17. Can be configured.

Next, several examples of application examples of the present invention will be described. First, as shown in FIG. 7, a lighting apparatus can be used as the transmission-side device 1. In this case, arbitrary information can be transmitted from each lighting fixture 31-33. For example, various information such as youth and music information can be transmitted by illumination light. For example, in a store such as a supermarket, information that the store wants to inform customers such as sale information, bargain information, and recommended menu information for the day can be transmitted. In addition, the same usage can be considered if the place is illuminated, such as in an event venue or train.

[0071] A user who wants to receive such information may use a portable terminal under illumination light, for example, having the above-described configuration of the present invention. Even when illumination light from a plurality of luminaires is received, each information can be received as described above. In addition, the range in which the intensity of the illumination light is strong is so wide. For example, even in a store, different information can be transmitted for each sales floor, and the information for each sales floor can be distributed to users at and near the sales floor. .

As another example, position information can be transmitted as information to be transmitted, for example. For example As shown in Fig. 7, when transmitting the position information of the lighting fixture power in the room, the illumination light does not pass through the wall, so the position can be detected in room units. For example, all the location information may be transmitted from the luminaire, or only the location information ID is transmitted from the luminaire, and the location information is queried through the network based on the ID received by the receiving side device 2. A configuration that fits together is also possible.

[0073] Outside the room, for example, in an underground shopping street, the use of lighting equipment on the passage, a shop sign, a neon sign, or the like as the transmitting device 1 can similarly detect the position in a underground shopping street where radio waves do not reach. is there. Of course, the location information can be transmitted and received in the same way if the location is illuminated outdoors, and the location information can be transmitted by street lamps at night.

[0074] A number of lighting fixtures are arranged, and the above-described configuration enables position detection with overwhelmingly high accuracy compared to the current GPS method. For example, it can be used to specify the location of a reporter at the time of an emergency call.

Brief Description of Drawings

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of transmission / reception timing in the first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a third embodiment of the present invention.

FIG. 5 is a block diagram showing a fourth embodiment of the present invention.

FIG. 6 is a block diagram showing a modification of the fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of an outline of a communication method using a lighting device as a transmitter.

Explanation of symbols

[0076] 1 ... Transmission side device, 2 ... Reception side device, 11 ... Light source, 12 ... Transmission processing unit, 13 ... Random number generation unit, 14 ... Transmission timing control unit, 15 ... Subcarrier frequency control unit, 16 ... ··· Spreading code control unit, 17 ··· Transmission wavelength control unit, ··· Light emission source selector, 19 ··· Light emission source, 24 ··· Light receiving element, 21 ··· Light receiving unit, 22 ··· Reception processing unit , 23 ... Collision judging unit, 31-33 ... Lighting equipment, 34 ... Receiver

Claims

The scope of the claims

[1] An optical communication system for transmitting information by emitting a modulated optical signal, and a light source that emits light by light emission, and modulating the given information to drive the light source and modulate the light source Transmitting means for transmitting the information by emitting light, random number generating means for generating random numbers, and timing control means for controlling transmission timing according to the random numbers generated by the random number generating means, An optical communication system, wherein the information is transmitted at a transmission timing controlled by a timing control means.

[2] Multiple light source powers An optical communication system in which modulated light modulated according to information is emitted at an arbitrary timing. The light receiving means receives the modulated light and converts it into an electrical signal, and is converted by the light receiving means. A receiving means that demodulates an electrical signal and receives information, and a signal of multiple light source forces collides with each other based on the electrical signal converted by the light receiving means or the signal demodulated by the receiving means! An optical communication system characterized by having a collision determination means for detecting a signal, and extracting only a bad signal when a collision occurs and using it as reception information.

[3] An optical communication method for transmitting information by emitting a modulated optical signal, a light source that emits light by light emission, and driving the light source by modulating the given information to modulate the light source Transmitting means for transmitting the information by emitting light, random number generating means for generating random numbers, and subcarrier frequency control means for controlling the subcarrier frequency according to the random numbers generated by the random number generating means, An optical communication system characterized in that the means transmits the information using a subcarrier frequency controlled by the subcarrier frequency control means.

[4] Multiple light source powers An optical communication system that emits modulated light at an arbitrary subcarrier frequency in a predetermined frequency band modulated according to information, and receives light that is converted into an electrical signal by receiving the modulated light. Means, a receiving means for demodulating each of the electric signals converted by the light receiving means, and all the subcarrier frequencies that can be taken on the transmission side, and a signal demodulated by the receiving means. Have a collision determination means for detecting that the signals of multiple light source powers collide with each other for each sub-carrier frequency! A characteristic optical communication system.

[5] An optical communication method for transmitting information by emitting a modulated optical signal, and a light source that emits light by light emission, and modulates the given information to drive the light source and modulate the light source the light Transmitting means for transmitting the information by emitting light, random number generating means for generating random numbers, and spreading code control means for determining a spreading code at the time of transmission according to the random numbers generated by the random number generating means, The means transmits the information using the spreading code determined by the spreading code control means.

A plurality of light source powers. An optical communication system in which modulated light is emitted with an arbitrary spreading code modulated according to information, a light receiving means for receiving the modulated light and converting it into an electric signal, and an electric signal converted by the light receiving means. Receiving means for separating and demodulating the signals into respective spreading codes, and collision determination for detecting that signals from a plurality of light sources collide with each spreading code based on the signals demodulated by the receiving means. An optical communication system characterized by having means and extracting only a false signal as reception information when there is a collision.

An optical communication method for transmitting information by emitting a modulated optical signal, a light source that emits modulated light in a specified wavelength region, and driving the light source by modulating given information Transmitting means for transmitting the information by emitting modulated light, a random number generating means for generating random numbers, and a transmission wavelength control means for determining the wavelength range of the light source in accordance with the random numbers generated by the random number generating means. The light source emits modulated light by the transmission means in a wavelength range determined by the transmission wavelength control means.

An optical communication system that emits an optical signal in an arbitrary wavelength range modulated according to multiple light source power information, and includes a light receiving means that receives light in each wavelength range and converts it into an electrical signal, and a light receiving means. Receiving means for demodulating each of the converted electrical signals corresponding to each wavelength band, and a plurality of light sources for each wavelength band based on the signal demodulated by the receiving means. An optical communication system characterized by having a collision determination means for detecting that signals collide and extracting only non-collised signals as received information