JP2008252466A - Optical communication system, transmitter and receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain data communication at a proper parallelism depending on a situation. <P>SOLUTION: The transmitter 10 divides a light source part 11 into a plurality of subareas, drives LEDs 12 belonging to the same subarea by a modulation signal obtained by modulating the same data and transmits data including information showing the subarea. The receiver 20 receives light including data, acquires the data by demodulation, allocates information for specifying data to be transmitted in each subarea on the basis of a pixel and information showing the subarea included in the received data, and generates an allocation map in which the information showing the subarea is associated with the information for specifying the data to be transmitted. The allocation map is transmitted to the transmitter 10, and the transmitter 10 transmits data in parallel according to information for specifying the data to be transmitted in each subarea on the basis of the allocation map. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical communication system and an optical communication method using an optical signal radiated into space as a communication medium.

  Along with the development of LD (laser diode) and LED (light emitting diode), a method of using visible light emitted from a lighting fixture as a communication medium has been proposed. Since lighting fixtures exist everywhere, if illumination light from the lighting fixtures can be used for communication, wireless communication can be realized simply by adding a new function to the lighting fixtures. In recent years, white LEDs having excellent characteristics such as long life and low power consumption are expected as a next-generation light source.

  In such an optical communication system using a visible light source, a transmitting device emits modulated light modulated from visible light based on data to be transmitted, and a receiving device receives and demodulates the modulated light. Data can be acquired.

  For example, the bandwidth available for communication of currently available white LEDs is about several MHz to several tens of MHz, and the throughput of the entire system is limited by the response speed of the LEDs. Therefore, a system (parallel variable optical communication system) has been proposed in which different packets are transmitted in parallel by a plurality of LEDs, and signals from the LEDs are received in parallel by a two-dimensional sensor (image sensor) (Patent Document 1, Non-patent document 1, Non-patent document 2).

In the proposed system, transmission data is divided into a plurality of packets and each packet is transmitted in parallel from each LED, thereby enabling high-speed communication independent of the response speed of a single LED.
JP 2006-191313 A “Parallel Wireless Optical Communication Using High Speed CMOS Image Sensor”, S.C. Miyauchi et al., International Symposium on Information Theory and its Applications (ISITA 2004), Parma, Italy, October 2004 "Design of high-speed parallel space visible light communication system using two-dimensional transceiver", Masanori Ishida et al., IEICE Technical Report, OCS 2005-20, pp. 49-54, May 2005 “Analysis of LED Allocation Algorithms for Parallel Wireless Optical Communication”, S.M. Miyauchi et al., IEEE Radioand Wireless Symposium (RWS) 2006, San Diego, USA, 191-194, January 2006

  In the parallel variable optical communication system, as the number of LEDs and the number of pixels of the two-dimensional sensor to be received are increased, that is, as the degree of parallelism is increased, the throughput is improved. Therefore, a high-speed visible light wireless LAN can be realized. I can expect.

  In the parallel variable optical communication system, as shown in FIG. 14, in the receiving apparatus 100, an illumination image of the LED 110 is formed on the two-dimensional sensor 101 by arranging the lens 102 in front of the two-dimensional sensor 101. ing.

  FIG. 15 is a diagram illustrating an image of the LED 110 formed on the two-dimensional sensor 101. In FIG. 15, each rectangle represents a pixel of the two-dimensional sensor 101, and each black circle represents an image of the LED 110. As shown in FIG. 15A, if the pixels of the two-dimensional sensor and the LED images all correspond one-to-one, all the pixels can receive light from different LEDs. However, in actuality, as shown in FIG. 15B, an image is projected with one of them rotated, or as shown in FIG. 15C, the LED array and the two-dimensional sensor are not parallel. In some cases, the image is projected in a distorted state. Thus, the correspondence between the LED and the pixel changes.

  Further, there may be a case where the number of LEDs is larger than the number of pixels of the two-dimensional sensor and a plurality of LED images are formed on the pixels of the two-dimensional sensor. In such a case, since images of a plurality of LEDs are projected on one pixel, interference between the LEDs of the transmitter becomes a problem.

  In the example shown in FIG. 16, the same data is transmitted for 2 × 2 LEDs. In FIG. 16, the same data is transmitted for the same pattern in the circle indicating the LED image. Among the pixels of the two-dimensional sensor shown in FIG. 16, the upper left, upper right, lower left, lower right, and center five pixels are projected with the image of the LED that transmits the same data, and the data can be received without any problem. Can do. However, for the other four pixels, an image of an LED that transmits different data is projected, and data cannot be received due to interference.

  An object of the present invention is to provide an optical communication system, a transmission device, and a reception device capable of performing data communication with an appropriate degree of parallelism according to the situation.

An object of the present invention is to provide an optical communication system that transmits data in parallel by emitting light from a plurality of light sources.
A light source unit including a plurality of light sources that emit light;
A division processing unit that divides the light source unit into a plurality of sub-areas, generates information for identifying the sub-areas and information on light sources belonging to the sub-areas, and stores the information in a memory;
A transmission processing unit that modulates given data to generate a modulation signal, drives each of the light sources by the modulation signal, emits modulated light from each of the light sources, and transmits the data. Transmission processing means configured to be able to drive light sources belonging to the same subarea with a modulated signal obtained by modulating the same data;
A transmission device including a reception unit capable of receiving a signal from the reception device, wherein the transmission processing unit drives the light source with a modulation signal obtained by modulating data including information indicating the subarea. Device, and
A light receiving sensor unit including a plurality of pixels for receiving light;
Receiving processing means for demodulating a signal based on light received by each of the pixels to obtain data;
Based on the data for each pixel acquired by the reception processing means, a reception map in which the pixel and information indicating the sub-area included in the data acquired by the pixel are associated with each other is generated, Based on the reception map, information for specifying the data to be transmitted is allocated for each subarea, and an allocation map in which information indicating the subarea and information for specifying data to be transmitted are associated with each other Assigning means to generate;
A transmission unit that transmits a signal including the allocation map to a reception unit of the transmission device;
This is achieved by an optical communication system characterized in that the transmission device transmits data in parallel according to information specifying the data to be transmitted for each of the subareas based on the allocation map.

  In a preferred embodiment, the division processing means of the transmission device is configured to exclude subareas that do not include information indicating subareas in the allocation map from division targets.

In another preferred embodiment, when referring to data acquired based on the light received by the pixel, the value indicating transmission quality is better than a predetermined first threshold, The transmitting means of the receiving device is configured to transmit a signal indicating an instruction to increase parallelism to the receiving means of the transmitting device;
The division processing means of the transmission device is configured to divide the sub-area according to the instruction to increase the degree of parallelism, and generate information specifying the sub-area and information of light sources belonging to the sub-area. The

In another preferred embodiment, when referring to data acquired based on the light received by the pixel, the value indicating the transmission quality is deteriorated below a predetermined second threshold, The transmission means of the reception device is configured to transmit a signal indicating an instruction to reduce parallelism to the reception means of the transmission device,
The division processing means of the transmission apparatus merges the subareas according to the instruction to reduce the degree of parallelism, generates a new subarea, specifies the new subarea, and the light sources belonging to the subarea Configured to generate the information.

  In a more preferred embodiment, the sub-area is merged so that the division processing means of the transmission device becomes a sub-area in a state before being divided into the current sub-area according to the instruction to reduce the degree of parallelism. Configured to do.

  In a preferred embodiment, when the sub-area is composed of a single light source, the assignment unit of the reception device uses the assignment map so that the same data is received in one pixel. Configured to generate.

Another object of the present invention is to provide an optical communication system that transmits data in parallel by emitting a plurality of light sources.
A light source unit including a plurality of light sources that emit light;
A division processing unit that divides the light source unit into a plurality of sub-areas, generates information for identifying the sub-areas and information on light sources belonging to the sub-areas, and stores the information in a memory;
A transmission processing unit that modulates given data to generate a modulation signal, drives each of the light sources by the modulation signal, emits modulated light from each of the light sources, and transmits the data. Transmission processing means configured to be able to drive light sources belonging to the same subarea with a modulated signal obtained by modulating the same data;
A receiving device capable of receiving a signal from the receiving device;
The transmission processing means is configured to drive a light source by a modulation signal obtained by modulating data including information indicating the sub-area; and
For each of the sub-areas, a receiving map that receives information indicating the sub-area and information specifying the data to be transmitted is received from the receiving device that has received the light emitted from the light source unit. This is achieved by a transmission apparatus configured to transmit data in parallel according to information specifying the data to be transmitted for each subarea based on an allocation map.

  In a preferred embodiment, the division processing means is configured to exclude subareas that do not include information indicating subareas in the allocation map from division targets.

  In another preferred embodiment, in response to the division processing means receiving an instruction to increase the degree of parallelism generated from the reception apparatus and generated based on the transmission quality in the reception apparatus, the subarea Is configured to generate information for specifying the subarea and information on the light sources belonging to the subarea.

  In another preferred embodiment, in response to the division processing means receiving an instruction to reduce the degree of parallelism generated based on the transmission quality in the receiving apparatus transmitted from the receiving apparatus, The subareas are merged to generate a new subarea, and information for specifying the new subarea and information about the light sources belonging to the subarea are generated.

  In a more preferred embodiment, the division processing means is configured to merge the sub-areas so as to become a sub-area in a state before being divided into the current sub-area according to the instruction to reduce the degree of parallelism. Is done.

Furthermore, an object of the present invention is a receiving device that receives light from the transmitting device,
A light-receiving sensor unit including a plurality of pixels that receive the light;
Receiving processing means for demodulating a signal based on light received by each of the pixels to obtain data;
Based on the data for each pixel acquired by the reception processing means, a reception map in which the pixel and information indicating the sub-area included in the data acquired by the pixel are associated with each other is generated, Based on the reception map, information for specifying the data to be transmitted is allocated for each subarea, and an allocation map in which information indicating the subarea and information for specifying data to be transmitted are associated with each other Assigning means to generate;
It is achieved by a receiving device comprising: a transmitting means for transmitting a signal including the allocation map to the transmitting device.

  In a preferred embodiment, when the sub-area is composed of a single light source, the allocation unit of the receiving device generates the allocation map such that the same data is received in one pixel. Configured as follows.

  According to the present invention, it is possible to provide an optical communication system, a transmission device, and a reception device capable of performing data communication with an appropriate degree of parallelism according to the situation.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of an optical communication system according to an embodiment of the present invention. As illustrated in FIG. 1, the optical communication system includes a transmission device 10 and a reception device 20.

  As illustrated in FIG. 1, the transmission device 10 includes a light source unit 11, a transmission processing unit 13, a division processing unit 14, a memory 15, a reception processing unit 16, and a sensor 17. In the present embodiment, the light source unit 11 is an LED array in which a plurality of LEDs 12 are two-dimensionally arranged. Of course, a light emitting element other than an LED such as an LD (laser diode) may be used. Moreover, LED12 is not limited to a two-dimensional arrangement | positioning, You may arrange | position in the linear form (one-dimensional form). In the present embodiment, visible light is emitted from the light source unit 11. That is, the light source unit 11 can also function as a lighting fixture.

  The transmission processing unit 13 generates a drive signal for driving each LED 12. For example, the transmission processing unit 13 generates a modulation signal obtained by modulating the given data, and drives each LED 12 of the light source unit 12. Thereby, the light including the data can be emitted from the light source unit 11. In the present embodiment, the transmission processing unit 13 can also provide a drive signal obtained by modulating the same data to all the LEDs 12. Alternatively, the transmission processing unit 13 can perform an operation of emitting modulated light by supplying a drive signal obtained by modulating the same data to the LEDs 12 belonging to the same subarea for each subarea described later. Further, the transmission processing unit 13 can sequentially apply a modulated drive signal to each sub-area or each LED 12 to sequentially emit the LEDs belonging to the sub-area or each LED.

  Note that the fact that the LED 12 of the light source unit 11 emits modulated light by the modulated drive signal generated by the transmission processing unit 13 is also included in the data transmission. Therefore, in this specification, the emission of the modulated light is also data. This is called transmission.

  The division processing unit 14 divides the light source unit 11 into a plurality of subareas based on information (allocation map) from the receiving device 20 described later, and subarea information (for example, subareas for specifying each subarea). The number and the LED number of the LED included in each sub-area) are stored in the memory 15.

  The memory 15 stores data to be transmitted as modulated light, programs executed by the transmission processing unit 13, the division processing unit 14, and the reception processing unit 16, and the like.

  The sensor 17 receives infrared rays from an infrared light emitting element 27 provided in the receiving device 20 described later. The reception processing unit 16 extracts data from a signal based on the light received by the sensor 17.

  The receiving device 20 includes a lens 21, a light receiving sensor unit 22, a reception processing unit 23, a memory 24, an allocation processing unit 25, a transmission processing unit 26, and an infrared light emitting element 27.

  The light receiving sensor unit 22 receives light from the light source unit 11 projected through the lens 21. In the light receiving sensor unit 22 according to the present embodiment, a plurality of light receiving elements (hereinafter referred to as “pixels”) 28 are arranged in a two-dimensional array. The lens 21 has an autofocus function and a zoom function, and can project an image of the LED 12 of the light source unit 11 on the light receiving sensor unit 22 at a predetermined zoom rate.

  The reception processing unit 23 can receive an electrical signal obtained by converting the light received by each pixel 28, demodulate each electrical signal, and extract data. Based on the demodulated data, the allocation processing unit 25 identifies the data received by each pixel, and generates a reception map in which the information identifying the pixel and the subarea (for example, the subarea number) is associated. Based on the reception map, an allocation map in which a packet number to be transmitted for each subarea is allocated is generated.

  The transmission processing unit 26 generates a signal including allocation map information and outputs the signal to the infrared light emitting element 27. As a result, infrared light including information on the allocation map is emitted from the infrared light emitting element 27 and received by the sensor 17 of the transmission device 10.

  As described above, in the present embodiment, data transmission (downlink communication) from the transmission device 10 to the reception device 20 is visible from the plurality of LEDs 12 of the light source unit 11 to the plurality of pixels 28 of the light receiving sensor unit 22. It is based on light (white visible light if the LED 12 is a white LED). On the other hand, data transmission (uplink communication) from the receiving device 20 to the transmitting device 10 uses infrared light from the infrared light emitting element 27 to the sensor 17.

  Hereinafter, processing executed in the optical communication system according to the present embodiment will be described. 2 and 3 are flowcharts showing processing and data communication executed in the optical communication system according to the present embodiment.

  First, the transmission processing unit 13 of the transmission device 10 gives a drive signal to each LED 12 of the light source unit 11 to transmit a predetermined pattern (predetermined pattern) from the LED 12 of the light source unit 11 (step 201). The reception processing unit 23 of the receiving device 20 searches for a predetermined pattern in all the pixels 28 (step 202). When the predetermined pattern is captured (step 203), the transmission processing unit 26 of the reception apparatus 20 transmits data for confirming whether the light is emitted from the transmission apparatus 10 (step 204). This is because the link is still disconnected between the transmission device 10 and the reception device 20 at this time. By receiving the response from the transmitting apparatus 10 (step 205), the recognition of the default pattern is completed (step 206).

  FIG. 4A is a diagram schematically showing the state of the light receiving sensor unit 12 in the initial state. In this example, 4 × 4 = 16 pixels are arranged in the light receiving sensor unit 12 (see, for example, reference numerals 401 and 402), and FIG. 4B shows the state at step 206 in FIG. Show. The portion indicated by reference numeral 410 is a predetermined pattern recognized.

  Next, the receiving device 20 moves the lens 21 to project the image of each LED 12 with the focus on the light receiving sensor unit 12 (step 207). FIG. 4C shows a state in which step 207 has been completed. In this example, 8 × 8 = 64 LED images (see reference numeral 420) are projected onto the light receiving sensor unit 12.

  Next, a serial transmission request is transmitted from the infrared light emitting element 27 by the transmission processing unit 26 of the receiving device 20 (step 208). When the serial transmission request is received by the sensor 17 of the transmitting device 10, in response to this, The transmission apparatus 10 starts data transmission by serial transmission (step 209). In data transmission by serial transmission in step 209, the transmission processing unit 13 drives each LED 12 with a drive signal obtained by modulating the same data. The serial transmission or serial transmission in step 209 is data transmission whose parallel degree is “1”, and the same data is transmitted from all the LEDs.

  During the serial transmission, the receiving apparatus 20 performs zooming by moving the lens (step 210). In zooming, the enlargement ratio of the image is adjusted so that as many pixels 28 of the light receiving sensor 12 as possible can receive data within a clear range of the image.

  When the zooming is completed, a value indicating the transmission quality is better than a predetermined threshold (for example, a state where the PER (Packet Error Rate) is smaller than the predetermined threshold Th1) and a certain time has elapsed, that is, if the transmission quality is stable. (Yes in step 301), the parallel processing increase instruction is transmitted from the infrared light emitting element 27 by the transmission processing unit 26 of the receiving device 20 (step 302).

  Note that, in order to increase the parallelism of data transmission by parallel transmission in the transmission device 10, the processes of steps 303 to 307 are executed below. The processes of steps 303 to 307 have a transmission quality at a predetermined level. It can be repeated as long as (for example, PER <Th1).

  When the parallel degree increase instruction is received, the area division processing unit of the transmission device 10 executes the sub-area division processing (step 303). FIG. 5 is a flowchart showing an example of subarea division processing executed by the division processing unit 14 according to the present embodiment. FIG. 6 is a diagram showing an example of a table defining subarea division according to size. 7 and 8 are diagrams illustrating examples of sub-area division according to the present embodiment.

  The sub area refers to a small area composed of one or more pixel groups obtained by dividing the light source unit 11. FIG. 7A shows a state in which zooming in step 210 has been completed, and reference numeral 700 represents an area of the image of the LED 12 projected on the light receiving sensor 12. This is divided into four subareas 711 to 713 as shown in FIG. Note that each subarea is assigned a number (subarea number) that identifies each subarea, and the subarea number and information (for example, LED number) of the LEDs that constitute the subarea are stored in the memory 15. In FIGS. 7A and 7B and FIGS. 8A and 8B to be described later, the numbers described in the sub area or adjacent to the sub area are sub area numbers.

  As illustrated in FIG. 5, the division processing unit 14 specifies a sub area to be processed (step 501). For example, in the state of FIG. 7A, the area 700 is specified as a processing target. In the example of FIG. 7B, the sub-areas 711 to 714 are sequentially processed.

  Next, the division processing unit 14 executes the processes of the following steps 503 to 506 unless it is determined that division is not possible (Yes in step 502). The state where it cannot be divided is a case where the sub-area is composed of a single LED.

  Further, the division processing unit 14 determines whether or not information (subarea number) indicating the subarea to be processed exists in the allocation map (step 503). Although the allocation map will be described in detail later, for each subarea, information (subarea number) indicating the subarea and information (packet number) specifying data to be transmitted are associated with each other, The data is transmitted from the receiving device 20 to the transmitting device 10 and stored in the memory 15 of the transmitting device 10.

  If the subarea number of the subarea to be processed exists in the latest allocation map, it is determined Yes in step 503, while if it does not exist in the latest allocation map, it is determined No in step 503. If it is determined YES in step 503, the division processing unit 14 divides the sub area according to the size of the sub area (the number of pixels in the horizontal direction and the vertical direction) to generate a new sub area (step). 505).

  As shown in FIG. 6, the division of sub-areas is defined by the number of LEDs x in the horizontal direction (x-axis direction) and the number of LEDs y in the vertical direction (y-axis direction). When x = 1 and y = 1 (reference numeral 601), further division is impossible (this excludes processing in step 502).

  When x ≦ 3 and y ≦ 3, each sub-area is divided so as to be composed of a single LED (reference numeral 602). On the other hand, if x / y ≧ 2, then two new sub-areas are generated by dividing into two in the horizontal direction (reference numeral 603), and if x / y ≦ 0.5, it is divided into two in the vertical direction. Two new subareas are generated (reference numeral 604). Also, between the case indicated by the reference numeral 603 and the case indicated by the reference numeral 604, that is, if 0.5 <x / y <2, four new sub-areas are generated by dividing into two in both the vertical and horizontal directions. (Reference numeral 605).

  When it is determined No in step 503, the division processing unit 14 excludes the subarea from the processing target, that is, the division target (step 504).

  The division processing unit 14 stores information on the newly generated subarea (for example, the subarea number and the number of the LED constituting the subarea) in the memory 15. Information on the sub-areas excluded from the processing target in step 504 is also stored in the memory 15 in the same manner.

  If the processing has not been completed for all subareas (No in step 507), the processing returns to step 501 and the same processing is executed for the next subarea.

  For example, in the state of FIG. 7B, the allocation map described later includes only subarea numbers “1”, “3”, and “4” of the subarea 711, the subarea 713, and the subarea 714. Therefore, when the process of FIG. 5 is being performed on the subarea 712 assigned the subarea number “2”, it is determined No in step 503 and the subarea 712 is excluded from the processing target. FIG. 8A shows a state in which the subarea 712 is excluded from the processing target and the subareas 711, 713, and 714 are further divided into a plurality of subareas.

  In the state of FIG. 8A, the allocation map described later includes only subarea numbers “3” to “7” and “9” to “11” of subareas 803 to 807 and subareas 809 to 811. It is. Therefore, when the processing of FIG. 5 is executed for the subareas 801, 802, 808, and 812 assigned with the subarea numbers “1”, “2”, “8”, and “12”, respectively, step 503 is performed. No, and the sub-areas 801, 802, 808, 812 are excluded from the processing targets.

  FIG. 8B shows a state in which the sub area shown in FIG. 8A is further divided to generate a new sub area. In this state, the subarea is composed of a single LED.

  When the subarea division processing is completed, the transmission processing unit 13 sequentially performs data transmission including the data of the subarea number of the subarea for each subarea (step 304). By data transmission, each LED 12 belonging to a subarea having a certain subarea number emits modulated light including data of the subarea number. This data transmission is sequentially performed from the subarea to which the small subarea number is given.

  The light receiving sensor unit 22 of the receiving device 20 receives light emitted from the LEDs 12 belonging to the sub-area. The signal from each pixel 28 is given to the reception processing unit 23, and the reception processing unit 23 demodulates the signal from each pixel 28 and extracts data. Here, data indicating the sub-area number is acquired from the pixel 28 onto which the image of the light emitted from the LED 12 is projected, and data is not acquired from the other pixels 28.

  The allocation processing unit 25 generates a reception map in which pixel numbers (pixel coordinates) are associated with subarea numbers based on the presence / absence of the obtained data, and stores the generated reception map in the memory 24 (step 305). FIGS. 9A to 9D are diagrams illustrating examples of reception maps according to the present embodiment. The reception maps 901 to 904 shown in FIGS. 9A to 9D are respectively transmitted when data is transmitted from the subareas shown in FIGS. 7A, 7B, 8A, and 8B. This corresponds to the reception map generated in the reception device 20.

  Next, the allocation processing unit 25 generates an allocation map in which packet numbers are allocated for each sub-area based on the reception map, and stores the allocation map in the memory 24 (step 306). When a plurality of LEDs 12 are included in the sub area, the sub area and the packet number correspond one-to-one. As a result, the same packet number is assigned to LEDs belonging to the same sub-area, and the assigned packet number is different if the sub-area is different.

  Therefore, when a plurality of LEDs 12 are included in a subarea, a packet number may be assigned to each subarea number, for example, in ascending order. In addition, the sub area number of the sub area that is not received by the pixel 28 of the light receiving sensor unit 22 is excluded from the allocation map. As a result, when the plurality of LEDs 12 are included in the sub area, the plurality of LEDs 12 belonging to the same sub area transmit the same data.

  FIGS. 10A to 10C are diagrams illustrating examples of allocation maps generated by the allocation processing unit 25 based on the reception maps illustrated in FIGS. 9A to 9C. In the reception map 901 shown in FIG. 9A, only the light from the LEDs belonging to the sub-area having the sub-area number 1 is received. Therefore, as shown in FIG. Indicates that data of packet number 1 is assigned to subarea number 1.

  In the reception map 902 shown in FIG. 9B, it can be seen that light from the LEDs belonging to the sub-areas having sub-area numbers 1, 3, and 4 is received. Therefore, as shown in FIG. 10B, the assignment map 1002 indicates that the packet numbers 1, 2, and 3 are assigned to the sub-area numbers 1, 3, and 4, respectively.

  Similarly, in the reception map 903 shown in FIG. 9C, it can be seen that light from LEDs belonging to subareas having subarea numbers 3 to 7 and 9 to 11 are received. Therefore, as shown in FIG. 10C, the allocation map 1003 indicates that packet numbers 1 to 8 are allocated to the sub-areas 3 to 7 and 9 to 11, respectively.

  The generated allocation map is transmitted from the receiving device 20 to the transmitting device 10 by uplink communication (step 307).

  On the other hand, when the sub-area is composed of a single LED 12, it is necessary to consider that the pixel 28 can receive the same signal, instead of simply sending a different signal for each sub-area.

  One pixel 28 may receive light from a plurality of subareas (in this case, the subarea has the same meaning as an LED). In this case, if different data is transmitted by the LED 12, there is a possibility that the signals interfere with each other and neither data can be received. Therefore, in the present embodiment, when the sub-area is composed of a single LED 12, a process is performed so that one pixel 28 can receive light including the same data.

  In this embodiment, in this process, for each pixel 28, the power of light received from each LED 12 is held in a memory 24 in a table (reception power table), and a desired power is obtained by referring to the reception power table. A D / U ratio that is a ratio of the power of the signal and the undesired signal is calculated, and a packet is assigned to the LED 12 based on the calculated D / U ratio. This allocation method is disclosed in Non-Patent Document 3.

  FIG. 11 is a flowchart illustrating an example of the allocation process according to the present embodiment. Based on the received light, the allocation processing unit 25 generates a received power map including the emitted subarea (corresponding to the LED in this case), the received power, and the packet number of the data to be transmitted, The received power map is sorted according to the received power (step 1101). The reception power map is generated for all the pixels 28 that have received light from the LEDs 12 of the transmission device 10.

  Also, the allocation processing unit 25 allocates packet numbers so that different data is transmitted from the respective LEDs in the received power map of each pixel 28 (step 1102). Actually, since the LEDs 12 emit data including different subarea numbers, this subarea number may be set as an initial packet number.

  Next, the allocation processing unit 25 initializes a parameter k for counting the number of repetitions of the calculation (step 1103).

  For each pixel, the allocation processing unit 25 sets the D sum to “D” as the sum of the received light power (reception power) “D” and the sum of the reception power of other signals as “U”. Is calculated (step 1104). If the DU ratio (D / U) is equal to or greater than the predetermined threshold value THR (Yes in step 1105), it is determined that data can be sufficiently received by the light of k LEDs, and the allocation processing unit 25 becomes a processing target. K LEDs are assigned to the corresponding pixel, and the same packet number is assigned to the k LEDs in the received power map so as to transmit the same data (step 1106). Pixels to which LEDs are assigned are excluded from subsequent processing targets. Further, k LEDs are also excluded from the subsequent processing targets.

  If it is determined No in step 1105, the allocation processing unit 25 determines whether or not the packet number allocation has been completed for the (k + 1) th LED (step 1107), and the packet number is confirmed. If it is determined that the allocation has been completed (No in step 1107), the allocation processing unit 25 uses the received power from the k + 1-th LED as “U”, which is the sum of the received power of other signals. (Step 1108).

  If the processing has not been completed for all the pixels (No in Step 1109), the allocation processing unit 25 executes the processing of Steps 1105 to 1108 for the next pixel. If it is determined Yes in step 1109, it is determined whether or not the parameter k has reached the maximum number of repetitions K (step 1110). If it is determined No in step 1110, the parameter k is incremented (step 1111), and the process returns to step 1104.

  If it is determined Yes in step 1110, the allocation processing unit 25 refers to the received power map for each pixel, and the LED number (subarea number) given the same packet number for each pixel. And an allocation map in which the subarea number and the packet number are associated with each other is generated (step 1112). The generated allocation map is transmitted from the receiving device 20 to the transmitting device 10 by uplink communication (step 307 in FIG. 3).

  FIG. 12 is a diagram illustrating an example of an allocation map generated by the allocation processing unit 25 based on the reception map illustrated in FIG. As shown in FIG. 12, when a subarea is composed of a single LED 12, the same packet number may be assigned to subareas (LEDs) having different subarea numbers (reference numerals 1201 and 1202). , Reference numerals 1203 and 1204, and reference numerals 1205 to 1207).

  As can be understood from FIG. 8B and FIG. 12, for pixels that can receive light from a plurality of LEDs, the same packet number is assigned to the plurality of LEDs, and the same data is transmitted from these LEDs. It will be. Thereby, it is possible to prevent signal collision and interference from occurring in the pixels in parallel transmission described later.

  The allocation map transmitted to the transmission device 10 is stored in the memory 15 of the transmission device 10, is referred to for data transmission by parallel transmission, and is referred to in the area division processing as described above. As described above, the processes in steps 303 to 307 can be repeated as long as the transmission quality is at a predetermined level (for example, PER <Th1). Therefore, the receiving apparatus 20 can further instruct to increase the degree of parallelism (step 302), and can request further subdivision of the subarea. In this case, the transmitting apparatus 10 executes Steps 303 and 304, and the receiving apparatus 20 also executes a process for generating an allocation map based on the data transmission in Step 304.

  After such processing, the transmission apparatus 10 starts data transmission by parallel transmission according to the allocation map stored in the memory 15 (step 308). In data transmission by parallel transmission, a plurality of types of data are transmitted simultaneously so that LEDs belonging to the same sub-area transmit the same data according to the allocation map. As a result, parallel transmission at a degree of parallelism corresponding to the number of packet numbers is realized.

  As described above, in the present embodiment, the transmission device 10 stores, in the memory 15, an allocation map in which a packet number indicating data to be transmitted is allocated for each subarea into which the light source unit 11 is divided. Parallel transmission is realized in which LEDs belonging to the same sub-area transmit the same data according to the packet number in the map. The allocation map is generated in the receiving device 20 based on the subarea number included in the data received by the pixel 28 of the light receiving sensor unit 22, and is transmitted from the receiving device 20 to the transmitting device 10 by uplink communication. Thereby, even when the one-to-one relationship is not established between the LED 12 of the light source unit 11 of the transmission device 10 and the pixel 28 of the light receiving sensor unit 22 of the reception device 20, data transmission by parallel transmission is realized.

  In the present embodiment, when the transmission quality is in a predetermined state (when the value indicating the transmission quality is better than a predetermined threshold value), the receiving device 20 instructs to increase the degree of parallelism, and the transmitting device 10 further divides the sub-area in accordance with an instruction to increase the degree of parallelism to increase the degree of parallelism, and data transmission from each of the divided sub-areas is realized.

  Furthermore, in this embodiment, when the sub-area is composed of a single LED, the same data is transmitted to a certain pixel so that there is no signal collision or interference in each pixel. Assignments are made.

  As described above, according to the present invention, when the focus adjustment is completed, data communication is started at an early stage, so that the time until link establishment can be shortened.

  The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above embodiment, when the transmission quality is in a predetermined state (indicating that the value indicating the transmission quality is better than a predetermined threshold), the receiving device 20 instructs to increase the parallelism. The transmitting apparatus 10 further divides the sub-area according to the instruction to increase the degree of parallelism. Further, when the transmission quality is deteriorated (when the value indicating the transmission quality is deteriorated from a predetermined threshold value), the receiving device 20 gives an instruction to reduce the parallelism to the transmitting device 10. You may comprise.

  FIG. 13 is a flowchart showing processing and data communication executed in the optical communication system according to the present embodiment. In a state where data transmission by parallel transmission is performed by the process shown in FIG. 3, when the value indicating the transmission quality is deteriorated below a predetermined threshold (for example, when PER becomes larger than the predetermined threshold Th2: In step 1301, the transmission processing unit 26 of the receiving device 20 transmits a parallel degree reduction instruction from the infrared light emitting element 27 (step 1302).

  The division processing unit 14 of the transmission device 10 refers to the information about the subarea stored in the memory 15 and the subarea information (subarea number and subarea before the division into the current subarea). (Information of LED to be configured) is acquired (step 1303). For example, if the current sub-area is in the state shown in FIG. 8B, information on the sub-area shown in FIG. 8A is acquired, and if the current sub-area is in the state shown in FIG. The information of the sub area shown in FIG. 7B is acquired.

  Next, the transmission processing unit 13 sequentially performs data transmission including data of subarea numbers of subareas for each subarea (step 1304). This process is the same as step 304 in FIG.

  The processing (steps 1305 to 1307) in the receiving apparatus 20 is the same as steps 305 to 307 in FIG. In addition, the transmission device 20 transmits data by parallel transmission based on the new allocation map transmitted from the reception device 20 (step 1308) is the same as step 308 in FIG.

  With such a configuration, when transmission quality deteriorates, data transmission by parallel transmission with the reduced parallelism can be continued by reducing the parallelism.

  In the example of FIG. 13, the reception device 20 newly generates an allocation map, and the transmission device 10 performs data transmission by parallel transmission according to the new allocation map. However, the present invention is not limited to such a configuration. The apparatus 10 may read the allocation map for the sub-areas merged in step 1303 from the memory 15 and resume data transmission by parallel transmission based on the allocation map.

  According to the above embodiment, the degree of parallelism can be dynamically changed even when transmission quality is deteriorated. In particular, as long as the transmission quality is good, as the degree of parallelism increases and degrades, dynamic control that reduces the degree of parallelism is moving not only when the receiving apparatus is stationary, but also moving. Even in the case (when it is a mobile terminal), the optimum throughput can be provided with the optimum degree of parallelism. Also, stable transmission can be realized by dynamic control of parallelism.

  In the present embodiment, the light of the white LED is used for downlink communication, but the present invention is not limited to this, and light of other colors or light from other elements may be used. . In addition, infrared communication is used for uplink communication, but the present invention is not limited to this. For example, wireless communication such as Bluetooth (registered trademark) may be used.

  The light source unit 11 and the light receiving sensor unit 12 may be rectangular or rectangular, and the LED (light source) and pixels may be one-dimensionally arranged (elongated shape).

FIG. 1 is a block diagram of an optical communication system according to an embodiment of the present invention. FIG. 2 is a flowchart showing processing and data communication executed in the optical communication system according to the present embodiment. FIG. 3 is a flowchart showing processing and data communication executed in the optical communication system according to the present embodiment. 4A is a diagram schematically illustrating the state of the light receiving sensor unit 12 in the initial state, FIG. 4B is a diagram illustrating the state in step 206 in FIG. 2, and FIG. It is a figure which shows the state which 207 completed. FIG. 5 is a flowchart illustrating an example of subarea division processing executed by the division processing unit 14 according to the present embodiment. FIG. 6 is a diagram illustrating an example of a table defining sub-area division according to size. FIG. 7 is a diagram illustrating an example of subarea division according to the present embodiment. FIG. 8 is a diagram illustrating an example of subarea division according to the present embodiment. FIGS. 9A to 9D are diagrams illustrating examples of reception maps according to the present embodiment. FIGS. 10A to 10C are diagrams illustrating examples of allocation maps generated by the allocation processing unit based on the reception maps illustrated in FIGS. 9A to 9C. FIG. 11 is a flowchart illustrating an example of the allocation process according to the present embodiment. FIG. 12 is a diagram illustrating an example of an allocation map generated by the allocation processing unit based on the reception map illustrated in FIG. FIG. 13 is a flowchart showing processing and data communication executed in the optical communication system according to the present embodiment. FIG. 14 is a block diagram illustrating an example of a parallel visible light communication system. FIG. 15 is a diagram illustrating an image of an LED formed on a two-dimensional sensor in the parallel visible light communication system. FIG. 16 is a diagram illustrating an image of an LED imaged on a two-dimensional sensor in the parallel visible light communication system.

Explanation of symbols

10 Transmitter 11 Light source 12 LED
DESCRIPTION OF SYMBOLS 13 Transmission process part 14 Division | segmentation process part 15 Memory 16 Reception process part 17 Sensor 20 Receiver 21 Lens 22 Reception sensor part 23 Reception process part 24 Memory 25 Assignment process part 26 Transmission process part 27 Infrared light emitting element 28 Pixel

Claims (13)

In an optical communication system that transmits data in parallel by emitting multiple light sources,
A light source unit including a plurality of light sources that emit light;
A division processing unit that divides the light source unit into a plurality of sub-areas, generates information for identifying the sub-areas and information on light sources belonging to the sub-areas, and stores the information in a memory;
A transmission processing unit that modulates given data to generate a modulation signal, drives each of the light sources by the modulation signal, emits modulated light from each of the light sources, and transmits the data. Transmission processing means configured to be able to drive light sources belonging to the same subarea with a modulated signal obtained by modulating the same data;
A transmission device including a reception unit capable of receiving a signal from the reception device, wherein the transmission processing unit drives the light source with a modulation signal obtained by modulating data including information indicating the subarea. Device, and
A light receiving sensor unit including a plurality of pixels for receiving light;
Receiving processing means for demodulating a signal based on light received by each of the pixels to obtain data;
Based on the data for each pixel acquired by the reception processing means, a reception map in which the pixel and information indicating the sub-area included in the data acquired by the pixel are associated with each other is generated, Based on the reception map, information for specifying the data to be transmitted is allocated for each subarea, and an allocation map in which information indicating the subarea and information for specifying data to be transmitted are associated with each other Assigning means to generate;
A transmission unit that transmits a signal including the allocation map to a reception unit of the transmission device;
An optical communication system, wherein the transmission device transmits data in parallel according to information specifying the data to be transmitted for each of the subareas based on the allocation map.   2. The light according to claim 1, wherein the division processing unit of the transmission device is configured to exclude subareas that do not include information indicating subareas in the allocation map from division targets. Communications system. When referring to the data acquired based on the light received by the pixel and indicating that the value indicating the transmission quality is better than a predetermined first threshold, the transmitting means of the receiving device, A signal indicating an instruction to increase parallelism is transmitted to the receiving means of the transmitting device;
The division processing means of the transmission device is configured to divide the sub-area according to the instruction to increase the degree of parallelism, and generate information specifying the sub-area and information of light sources belonging to the sub-area. The optical communication system according to claim 1 or 2, wherein When the data acquired based on the light received by the pixel indicates that the value indicating the transmission quality has deteriorated below a predetermined second threshold, the transmission unit of the receiving device A signal indicating a decrease instruction, configured to transmit to a receiving means of the transmitting device;
The division processing means of the transmission apparatus merges the subareas according to the instruction to reduce the degree of parallelism, generates a new subarea, specifies the new subarea, and the light sources belonging to the subarea The optical communication system according to claim 3, wherein the information is generated.   The division processing means of the transmission device is configured to merge the sub-areas so as to become sub-areas in a state before being divided into current sub-areas according to the instruction to reduce the parallelism. The optical communication system according to claim 4.   When the sub-area is composed of a single light source, the allocation unit of the reception device is configured to generate the allocation map so that the same data is received in one pixel. The optical communication system according to any one of claims 1 to 5, wherein: In an optical communication system that transmits data in parallel by emitting multiple light sources,
A light source unit including a plurality of light sources that emit light;
A division processing unit that divides the light source unit into a plurality of sub-areas, generates information for identifying the sub-areas and information on light sources belonging to the sub-areas, and stores the information in a memory;
A transmission processing unit that modulates given data to generate a modulation signal, drives each of the light sources by the modulation signal, emits modulated light from each of the light sources, and transmits the data. Transmission processing means configured to be able to drive light sources belonging to the same subarea with a modulated signal obtained by modulating the same data;
A receiving device capable of receiving a signal from the receiving device;
The transmission processing means is configured to drive a light source by a modulation signal obtained by modulating data including information indicating the sub-area; and
For each of the sub-areas, a receiving map that receives information indicating the sub-area and information specifying the data to be transmitted is received from the receiving device that has received the light emitted from the light source unit. A transmission apparatus configured to transmit data in parallel according to information specifying the data to be transmitted for each of the sub-areas based on an allocation map.   8. The transmission apparatus according to claim 7, wherein the division processing unit is configured to exclude subareas that do not include information indicating subareas in the allocation map from division targets.   In response to the division processing means receiving an instruction to increase the degree of parallelism generated based on the transmission quality in the receiving apparatus transmitted from the receiving apparatus, the sub-area is divided into the sub-areas. The transmission device according to claim 7 or 8, wherein the transmission device is configured to generate information for identifying a light source and information on a light source belonging to the sub-area.   In response to receiving the instruction to reduce the degree of parallelism generated based on the transmission quality in the receiving apparatus transmitted from the receiving apparatus, the division processing unit merges the subareas to generate a new subarea. The transmission device according to claim 9, wherein the transmission device is configured to generate an area and generate information for specifying a new sub-area and information on a light source belonging to the sub-area.   The division processing means is configured to merge the sub-areas so as to become a sub-area in a state before being divided into the current sub-area according to the instruction to reduce the degree of parallelism. The transmission device according to claim 10. A receiver that receives light from the transmitter according to any one of claims 7 to 11,
A light-receiving sensor unit including a plurality of pixels that receive the light;
Receiving processing means for demodulating a signal based on light received by each of the pixels to obtain data;
Based on the data for each pixel acquired by the reception processing means, a reception map in which the pixel and information indicating the sub-area included in the data acquired by the pixel are associated with each other is generated, Based on the reception map, information for specifying the data to be transmitted is allocated for each subarea, and an allocation map in which information indicating the subarea and information for specifying data to be transmitted are associated with each other Assigning means to generate;
Transmitting means for transmitting a signal including the allocation map to the transmitting apparatus.   When the sub-area is composed of a single light source, the allocation unit of the reception device is configured to generate the allocation map so that the same data is received in one pixel. The receiving device according to claim 12.