JP2011135206A - Optical wireless communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical wireless communication device for achieving highly efficient transmission to be obtained by parallel transmission by identifying respective optical signals in a plurality of light receiving elements even when a plurality of light receiving elements receive optical signals transmitted from a plurality of light emitting elements in a mixture state. <P>SOLUTION: In the optical wireless communication device, a transmitter adjusts the signal intensity of an optical signal to be transmitted, based on a feedback signal transmitted from a receiver. The receiver receives a plurality of optical signals, generates signal point arrangement information indicating a reception level for reception in the receiver corresponding to an optical signal pattern transmitted from the transmitter, defines, as a reception signal, the sum of a plurality of reception electric signals converted from a plurality of optical signals, identifies, from the reception signal, the optical signal pattern transmitted from the transmitter, based on the signal point arrangement information, and then, transmits the feedback signal, based on the signal point arrangement information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical wireless communication apparatus that performs wireless communication using infrared rays or visible light, and more particularly to an optical wireless communication apparatus that performs high-efficiency transmission using parallel transmission.

  As a conventional wireless communication system, an optical wireless communication system using light is known. The optical wireless communication system can be broadly divided into a system using parallel light and a system using diffused light.

  Among these, the method using parallel light uses a beam output from a laser as parallel light, and is mainly used for communication between buildings. As a feature of the system using parallel light, since there is no loss due to the spread of light, transmission over a relatively long distance is possible, but there is a problem that complicated optical axis adjustment is necessary.

  On the other hand, the method using diffused light uses a light emitting diode (LED) or laser, a diffusion plate, and the like. Compared to a system using parallel light, the system using diffused light has the advantage that a complicated optical axis adjustment is not required because the reception range in the direction orthogonal to the optical axis can be widened. On the other hand, in the method using diffused light, the transmission distance is limited to a relatively short distance due to loss due to light diffusion (proportional to the square of the distance). As an application example of a system using diffused light, there is data communication (IrDA: Infrared Data Association) using infrared rays, visible light communication using illumination light, or the like.

  By the way, when increasing the transmission speed in optical wireless communication, it is necessary to use high-speed light emitting elements and light receiving elements. However, the light receiving element generally has a property that the element area decreases as the speed increases. In optical wireless communication, when the area of the light receiving element is reduced, the received light power is reduced when the optical power (incident illuminance) per unit area incident on the light receiving element is the same. Therefore, in order to secure the same received power as when the transmission speed is low (that is, when the light receiving element is large), it is necessary to increase the incident illuminance incident on the light receiving element. In this case, the higher the speed, the smaller the distance that can be transmitted.

  Therefore, by reducing the directivity angle at the transmitter, it is also possible to increase the incident illuminance incident on the light receiving element of the receiver, but in this case, the reception range in the direction orthogonal to the optical axis is limited, The advantage of using diffused light is impaired. Thus, in the method using diffused light, the transmission speed, transmission distance, and reception range are in a trade-off relationship.

  As one method corresponding to this, there is a method of preparing a plurality of light emitting elements and light receiving elements and performing parallel transmission. When parallel transmission is performed, the transmission speed per channel can be suppressed, so that the area of the light receiving element can be increased. For this reason, the restriction | limiting of the transmission distance by the system using a diffused light can be eased. However, in the case of a system using diffused light, if the transmission distance is increased, optical signals transmitted from a plurality of light emitting elements of the transmitter are mixed, and the receiver cannot identify each optical signal received by the light receiving element. There is a problem that information transmitted from the transmitter (light emitting element) cannot be correctly reproduced.

  An example of a conventional method for dealing with this problem is disclosed in Patent Document 1. FIG. 10 is a diagram showing a conventional optical wireless communication apparatus 900. As shown in FIG. In FIG. 10, the optical wireless communication apparatus 900 assumes a case where a plurality of light emitting units (optical transmitters) 901 and 902 transmit information to a plurality of information terminals 903 and 904 that are individually associated with each other. The information terminals 903 and 904 have light receiving units 905 and 906, respectively.

  FIG. 11 is a diagram showing an information format 950 of data transmitted by the first light emitting unit 901 and the second light emitting unit 902. 11, the information format 950 has a configuration in which a header portion 951, a common information portion 952, a unique information portion 953, and an error detection portion 954 are arranged in time series. The header section 951 stores necessary header information. In the common information section 952, information common to the first light emitting unit 901 and the second light emitting unit 902 is stored. In the unique information section 953, different unique information for the first light emitting unit 901 and the second light emitting unit 902 is stored. The error detection unit 954 stores error detection information. The error detection information is additional information for detecting whether a part of the data in the information format 950 is broken due to, for example, noise on the transmission path or interference.

  When the first information terminal 903 and the second information terminal 904 receive only the optical signal transmitted from either one of the first light emitting unit 901 and the second light emitting unit 902, they are common. Information of both the information part 952 and the unique information part 953 can be received correctly. On the other hand, when the first information terminal 903 and the second information terminal 904 receive the optical signals transmitted from the first light emitting unit 901 and the second light emitting unit 902 in a mixed state, the respective unique information sections The information 953 cannot be received correctly, but the information in each common information section 952 is common and can be received correctly. As described above, even if the optical signals transmitted from the first light emitting unit 901 and the second light emitting unit 902 are mixed, the first information terminal 903 or the second information terminal 904 is common to the respective information terminals. Information in the information section 952 can be received correctly.

JP 2009-124533 A

  However, in the conventional optical wireless communication apparatus 900, when the optical signals transmitted from the first light emitting unit 901 and the second light emitting unit 902 are mixed, all the information included in each unique information section 953 is lost. Therefore, only the information included in each common information part can be transmitted. That is, the conventional optical wireless communication apparatus 900 has a problem that the transmission efficiency is lower than that in the case where transmission is performed using only one channel, although parallel transmission is used.

  Therefore, an object of the present invention is to solve the above-described conventional problems, and in an optical wireless communication apparatus using a plurality of light emitting elements and a plurality of light receiving elements, the plurality of light receiving elements are separated from the plurality of light emitting elements. An optical wireless communication device that realizes high-efficiency transmission obtained by parallel transmission by identifying each optical signal with a plurality of light receiving elements even when the transmitted optical signals are mixed and received. Is to provide.

  To achieve the above object, an optical wireless communication apparatus of the present invention is an optical wireless communication apparatus that performs data communication using a plurality of optical signals between a transmitter and a receiver, and the transmitter includes a plurality of Based on the feedback signal, a plurality of optical transmitters that convert the transmission electrical signal into an optical signal and transmit a plurality of optical signals, respectively, and a feedback signal indicating that the plurality of transmission electrical signals are adjusted are received from the receiver. A transmission signal control unit that generates a transmission signal control information and a transmission signal control unit that adjusts a plurality of transmission electric signals based on the transmission signal control information, the receiver receives a plurality of optical signals, Optical signals transmitted from a plurality of optical transmitters based on a plurality of optical receivers that respectively convert the optical signals of the optical signals into received electrical signals and a plurality of received electrical signals converted by the plurality of optical receivers A reception signal analysis unit that generates signal point arrangement information indicating reception levels of a plurality of optical reception units corresponding to turns, and a feedback that generates a feedback signal based on the signal point arrangement information and transmits the generated feedback signal A transmission unit and a reception signal control unit that identifies the optical signal pattern transmitted from the plurality of optical transmission units from the reception signal based on the signal point arrangement information using the sum of the plurality of received electrical signals as the reception signal. .

  The preferred feedback signal includes information indicating that the signal strengths of the plurality of transmission electric signals are adjusted so that the optical signal patterns transmitted from the plurality of optical transmission units can be identified from the reception signal, and the transmission signal control The unit includes a transmission signal strength adjustment unit that adjusts signal strengths of a plurality of transmission electrical signals.

  Further, the preferable feedback signal includes information indicating whether any one or all of the plurality of transmission electric signals are the same signal or different signals, and the transmission signal control unit includes the plurality of transmission electric signals. Among these, a transmission signal selection unit that selects whether any or all of them are the same signal or different signals is included.

  Further, the preferable reception signal analysis unit outputs the plurality of reception electric signals as they are based on the plurality of reception electric signals converted by the plurality of optical reception units, or uses the sum of the plurality of reception electric signals as the reception signal. The reception signal switching information indicating whether to output is generated, and the reception signal control unit outputs the plurality of reception electric signals as they are based on the reception signal switching information or uses the sum of the plurality of reception electric signals as the reception signal. Based on the received signal switching section to be output and the signal point arrangement information, the plurality of optical signals transmitted from the plurality of optical transmission sections are identified from the plurality of received electrical signals or received signals output from the received signal switching section. And a reception signal identification unit.

  In order to achieve the above object, a receiver of the present invention is a receiver that receives a plurality of optical signals transmitted from a plurality of optical transmission units of a transmitter, and transmits from the plurality of optical transmission units of the transmitter. A plurality of optical receivers that respectively receive the plurality of optical signals and convert the plurality of optical signals into received electrical signals, and the plurality of received electrical signals converted by the plurality of optical receivers, A received signal analyzer that generates signal point arrangement information indicating reception levels of a plurality of optical receivers corresponding to optical signal patterns transmitted from a plurality of optical transmitters; and a plurality of transmitters based on the signal point arrangement information A feedback signal indicating that a plurality of optical signals transmitted from the optical transmitter are adjusted, a feedback transmitter that transmits the generated feedback signal, and a sum of the plurality of received electrical signals as a received signal. point Based on the location information, from the received signal, and a reception signal controller identifies the optical signal pattern transmitted from a plurality of optical transmitters of the transmitter.

  In order to achieve the above object, a reception method of the present invention is a reception method executed by a receiver that receives a plurality of optical signals transmitted from a plurality of optical transmission units of a transmitter by a plurality of optical reception units. A plurality of optical signals transmitted from a plurality of optical transmission units of the transmitter are received by the plurality of optical reception units, and the plurality of optical signals are converted into received electrical signals, respectively, and converted in the optical reception step. A received signal analysis step for generating signal point arrangement information indicating reception levels of the plurality of optical receivers with respect to the optical signal pattern transmitted from the plurality of optical transmitters of the transmitter based on the plurality of received electrical signals; Based on the signal point arrangement information, a feedback signal indicating that a plurality of optical signals transmitted from a plurality of optical transmission units of the transmitter are adjusted is generated, and the generated feedback signal is transmitted. Feedback signal transmission step and reception signal control for identifying the optical signal pattern transmitted from the plurality of optical transmitters of the transmitter from the received signal based on the signal point arrangement information using the sum of the plurality of received electrical signals as the received signal Steps.

  According to the optical wireless communication apparatus of the present invention, in the optical wireless communication apparatus using a plurality of light emitting elements and a plurality of light receiving elements, the plurality of light receiving elements receive a mixed state of optical signals transmitted from the plurality of light emitting elements. Even in this case, the plurality of light receiving elements can realize high-efficiency transmission obtained by parallel transmission by identifying each optical signal.

The figure which shows the optical wireless communication apparatus 100 which concerns on one Embodiment of this invention. The figure which shows the relationship between the transmission distance of the transmitter 10 shown in FIG. 1 and the receiver 20, and the reception level of the optical signal which the 1st optical receiver 210 in the receiver 20 receives. The figure which shows the mode of transmission of 1st optical signal S31 and 2nd optical signal S32 according to the transmission distance of the transmitter 10 and the receiver 20 which were shown in FIG. The figure which shows the information format 500 of the optical signal which the 1st optical transmission part 120 and the 2nd optical transmission part 130 transmit. The figure which shows the transmission level of 1st optical signal S31 and 2nd optical signal S32 transmitted from the 1st optical transmission part 120 and the 2nd optical transmission part 130 In a state where the first optical signal S31 and the second optical signal S32 are not mixed, the first optical reception unit 210 and the second optical reception unit 220 respectively correspond to the first optical signal S31 and the second optical signal. The figure which shows the case where only signal S32 is received In a state where the first optical signal S31 and the second optical signal S32 are mixed, the first optical receiving unit 210 and the second optical receiving unit 220 are connected to the first optical signal S31 and the second optical signal S32. Figure showing the case of receiving both The figure shown about the method in which the received signal analysis part 240 produces | generates signal point arrangement | positioning information S27. The figure which shows signal point arrangement | positioning information S27 which the received signal analysis part 240 produces | generates when the transmission level of 2nd optical signal S32 is adjusted to 3/4 times The figure which shows the signal point arrangement | positioning information S27 which the received signal analysis part 240 produces | generates when the transmission level of 2nd optical signal S32 is adjusted to 1/2 time. 1 shows a conventional optical wireless communication apparatus 900 The figure which shows the information format 950 of the data which the 1st light emission unit 901 and the 2nd light emission unit 902 transmit.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an optical wireless communication apparatus 100 according to an embodiment of the present invention. In FIG. 1, the optical wireless communication apparatus 100 includes a transmitter 10 and a receiver 20.

  The transmitter 10 includes a transmission signal control unit 110, a first optical transmission unit 120, a second optical transmission unit 130, and a feedback reception unit 140. The transmission signal control unit 110 includes a transmission signal selection unit 111 and a transmission signal strength adjustment unit 112.

  The receiver 20 includes a first optical receiver 210, a second optical receiver 220, a received signal controller 230, a received signal analyzer 240, and a feedback transmitter 250. The reception signal control unit 230 includes a reception signal switching unit 231 and a reception signal identification unit 232.

  In the transmitter 10, the transmission signal control unit 110 generates a plurality of transmission electric signals from the transmission data S <b> 11 based on the transmission signal control information S <b> 16 generated by the feedback reception unit 140. A detailed description of the plurality of transmission electrical signals generated by the transmission signal control unit 110 will be given later.

  The first optical transmission unit 120 and the second optical transmission unit 130 convert the plurality of transmission electrical signals generated by the transmission signal control unit 110 into the first optical signal S31 and the second optical signal S32, respectively. The first optical signal S31 and the second optical signal S32 are transmitted to the receiver 20. The first optical transmission unit 120 and the second optical transmission unit 130 include a light emitting element, a driving circuit thereof, a lens that adjusts the directivity of an optical signal to be transmitted, and the like.

  In the receiver 20, the first optical receiver 210 and the second optical receiver 220 receive the first optical signal S31 and the second optical signal S32 transmitted from the transmitter 10, and receive the first optical signal S31 and the second optical signal S32. Based on the optical signal S31 and the second optical signal S32, a first received electrical signal S21 and a second received electrical signal S22 are generated. The first optical receiving unit 210 and the second optical receiving unit 220 include a lens that collects an optical signal, a light receiving element, an amplifier circuit, and the like.

  The reception signal analysis unit 240 receives reception signal switching information S26 based on the first reception electrical signal S21 and the second reception electrical signal S22 generated by the first optical reception unit 210 and the second optical reception unit 220. The signal point arrangement information S27 and the feedback information S28 are generated. Detailed description of the received signal switching information S26, the signal point arrangement information S27, and the feedback information S28 will be described later.

  The reception signal control unit 230 generates a first signal from the first reception electric signal S21 and the second reception electric signal S22 based on the reception signal switching information S26 and the signal point arrangement information S27 generated by the reception signal analysis unit 240. Reception data S24 and second reception data S25 are generated.

  The feedback transmission unit 250 generates a feedback signal S33 based on the feedback information S28 generated by the received signal analysis unit 240, and transmits the feedback signal S33 to the transmitter 10. Then, in the transmitter 10, the feedback receiver 140 generates transmission signal control information S <b> 16 based on the feedback signal S <b> 33 transmitted from the receiver 20.

  Further, here, the transmitter 10 and the receiver 20 face each other, and the first optical transmission unit 120 and the first optical reception unit 210, and the second optical transmission unit 130 and the second optical reception unit 220, Are facing each other.

  Next, the operation of the optical wireless communication apparatus 100 will be described. FIG. 2 is a diagram illustrating a relationship between the transmission distance between the transmitter 10 and the receiver 20 illustrated in FIG. 1 and the reception level of the optical signal received by the first optical receiver 210 in the receiver 20. The first optical receiver 210 receives the first optical signal S31 and the second optical signal S32, but receives the optical signal according to the transmission distance between the transmitter 10 and the receiver 20, as shown in FIG. The reception levels of the first optical signal S31 and the second optical signal S32 are different. FIG. 3 is a diagram illustrating a state of transmission of the first optical signal S31 and the second optical signal S32 according to the transmission distance between the transmitter 10 and the receiver 20 illustrated in FIG.

  2A and 3B, (A) in the case of a short distance, the first optical receiver 210 detects the reception level of the first optical signal S31 transmitted from the corresponding first optical transmitter 120, and The reception level of the second optical signal S32 transmitted from the second optical transmission unit 130 is not detected, or a slight reception level that does not affect signal identification is detected. That is, the receiver 20 can identify the first optical signal S31 and the second optical signal S32 separately and accurately by the first optical receiver 210 and the second optical receiver 220, respectively.

  (B) In the case of a medium distance, the first optical receiver 210 detects the reception level of the first optical signal S31 transmitted from the corresponding first optical transmitter 120, and further the second optical transmitter The reception level of the second optical signal S32 transmitted from 130 is also detected. That is, the reception level detected by the first optical receiver 210 is a state in which the first optical signal S31 and the second optical signal S32 are mixed. Therefore, the receiver 20 needs to identify the first optical signal S31 and the second optical signal S32 based on the respective reception levels detected by the first optical reception unit 210 and the second optical reception unit 220. There is.

  (C) In the case of a long distance, the first optical receiver 210 detects the reception level of the first optical signal S31 transmitted from the corresponding first optical transmitter 120, and further the second optical transmitter The reception level of the second optical signal S32 transmitted from 130 is also detected. That is, the reception level detected by the first optical receiver 210 is a state in which the first optical signal S31 and the second optical signal S32 are mixed. However, in this case, unlike the case of (B) medium distance, the reception level itself detected by the first optical receiver 210 is small. Therefore, the receiver 20 identifies the first optical signal S31 and the second optical signal S32 based on the respective reception levels detected by the first optical reception unit 210 and the second optical reception unit 220. I can't.

Thus, the reception level of the optical signal received by the first optical receiver 210 and the second optical receiver 220 depends on the positional relationship between the transmitter 10 and the receiver 20. Furthermore, specifically, when focusing on the optical signals received by the first optical receiver 210 and the second optical receiver 220, there are the following two cases.
(1) In a state where the first optical signal S31 and the second optical signal S32 transmitted from the first optical transmission unit 120 and the second optical transmission unit 130 are not mixed, the first optical reception unit 210 and the second optical transmission unit 210 When the two optical receivers 220 receive only the corresponding first optical signal S31 and second optical signal S32, respectively (2) transmitted from the first optical transmitter 120 and the second optical transmitter 130 When the first optical receiver 210 and the second optical receiver 220 receive a plurality of optical signals in a state where the first optical signal S31 and the second optical signal S32 are mixed.

  Hereinafter, a method for the receiver 20 to identify the optical signal transmitted from the transmitter 10 will be described in detail.

  FIG. 4 is a diagram illustrating an information format 500 of an optical signal transmitted by the first optical transmission unit 120 and the second optical transmission unit 130. In FIG. 4, the information format 500 includes a header part 501 and a data part 502. As shown in FIG. 4 (1), the first optical signal S31 transmitted from the first optical transmission unit 120 includes a header 501 indicating that the transmission is from the first optical transmission unit 120. 1 header information is stored, and first transmission information that is data to be transmitted is stored in the data portion 502. As shown in FIG. 4 (2), the second optical signal S32 transmitted from the second optical transmission unit 130 indicates that the header unit 501 indicates transmission from the second optical transmission unit 130. 2 header information is stored, and second transmission information that is data to be transmitted is stored in the data portion 502.

  FIG. 5 is a diagram illustrating the transmission levels of the first optical signal S31 and the second optical signal S32 transmitted from the first optical transmission unit 120 and the second optical transmission unit 130. In FIG. 5, in the header period of the first optical signal S31 and the second optical signal S32, the transmission timing is time-division (t1, t2,..., Tn-1, tn), and the first optical transmission unit 120 and the second optical transmitter 130. Specifically, the 1st optical transmission part 120 and the 2nd optical transmission part 130 are allocated alternately for every 1 bit. As shown in FIG. 5A, the first optical transmission unit 120 transmits the first optical signal S31 having a predetermined transmission level at t1, t3,. As shown in FIG. 5 (2), the second optical transmitter 130 transmits a second optical signal S32 having a predetermined transmission level at t2, t4,.

  FIG. 6A shows a state in which the first optical signal S31 and the second optical signal S32 are not mixed, and the first optical signal receiving unit 210 and the second optical signal receiving unit 220 respectively correspond to the corresponding first optical signal S31 and It is a figure which shows the case where only 2nd optical signal S32 is received. That is, it is the case of (A) short distance shown in FIG. 2 and FIG. The first optical receiver 210 receives an optical signal having a predetermined reception level at t1, t3,..., Tn−1 as shown in FIG. As shown in FIG. 6A (2), the second optical receiver 220 receives an optical signal having a predetermined reception level at t2, t4,. Then, the first optical receiver 210 converts the received optical signal into a first received electrical signal S21, and the second optical receiver 220 converts the received optical signal into a second received electrical signal S22. To do.

  Next, the reception signal analysis unit 240 generates reception signal switching information S26 and signal point arrangement information S27 based on the first reception electric signal S21 and the second reception electric signal S22. Here, the received signal switching information S26 refers to either the first received electrical signal S21 or the second received electrical signal S22, which is selected as the received signal S23, or the first received electrical signal. This is information indicating whether the sum of S21 and the second received electrical signal S22 is the received signal S23 (multilevel signal). The signal point arrangement information S27 is the first optical signal S31 transmitted from the first optical transmitter 120 and the second optical signal S32 transmitted from the second optical transmitter 130. This is information indicating the reception level of the optical signal received by the optical receiver 210 and the second optical receiver 220. Specifically, in the signal point arrangement information S27, (1) when the first optical signal S31 and the second optical signal S32 are not transmitted, (2) only the first optical signal S31 is transmitted. In the case, (3) only the second optical signal S32 is transmitted, and (4) the first optical receiver 210 in the case where the first optical signal S31 and the second optical signal S32 are transmitted. And information indicating the reception level of the optical signal received by the second optical receiver 220.

  In this case, the received signal analysis unit 240 performs the first optical signal S31 and the second optical signal S32 on the basis of the first received electric signal S21 and the second received electric signal S22 in a state where the first optical signal S31 and the second optical signal S32 are not mixed. It is determined that the optical receiver 210 and the second optical receiver 220 receive only the corresponding first optical signal S31 and second optical signal S32, respectively.

  Thereby, the received signal analyzing unit 240 generates the received signal switching information S26 and the signal point arrangement information S27 based on the determined result. Here, the received signal switching information S26 is information indicating that one of the first received electrical signal S21 and the second received electrical signal S22 is selected as the received signal S23. The signal point arrangement information S27 is information indicating that the first optical receiving unit 210 and the second optical receiving unit 220 receive only the corresponding first optical signal S31 and second optical signal S32, respectively. It is.

  Then, the reception signal control unit 230 generates the first reception electric signal S21 and the second reception electric signal S22 based on the reception signal switching information S26 and the signal point arrangement information S27 generated by the reception signal analysis unit 240. One reception data S24 and second reception data S25 are generated.

  Specifically, the reception signal control unit 230 includes a reception signal switching unit 231 and a reception signal identification unit 232. Based on the signal switching control signal S26 generated by the received signal analyzing unit 240, the received signal switching unit 231 receives either the first received electrical signal S21 or the second received electrical signal S22 as a received signal. Output as S23. The received signal identifying unit 232 generates first received data S24 and second received data S25 from the received signal S23 based on the signal point arrangement information S27 generated by the received signal analyzing unit 240. Here, in a state where the first optical signal S31 and the second optical signal S32 are not mixed, the first optical reception unit 210 and the second optical reception unit 220 respectively correspond to the corresponding first optical signal S31 and second optical signal S31. Since only the second optical signal S32 is received, the first received electrical signal S21 and the second received electrical signal S22 are output as the first received data S24 and the second received data S25, respectively.

  In addition, the reception signal analysis unit 240 generates feedback information S28 based on the first reception electric signal S21 and the second reception electric signal S22. Here, the feedback information S28 is information for controlling the optical signal transmitted from the transmitter 10. In this case, since the receiver 20 has received and identified the first optical signal S31 and the second optical signal S32 in a state where the first optical signal S31 and the second optical signal S32 are not mixed, The feedback information S28 is information indicating that there is no need to adjust the signal intensity of the first optical signal S31 and the second optical signal S32.

  The feedback transmission unit 250 generates a feedback signal S33 based on the feedback information S28 generated by the reception signal analysis unit 240, and transmits the feedback signal S33 to the transmitter 10.

  As shown in FIG. 5, after the header period has elapsed, transmission information is transmitted from the transmitter 10, but the feedback transmission unit 250 has a feedback signal before transmission of transmission information from the transmitter 10 is started. S33 is transmitted to the transmitter 10. However, when full-duplex transmission is not possible between the transmitter 10 and the receiver 20, such as when the feedback signal S33 is mixed in the first optical signal S31 or the second optical signal S32 as crosstalk, the header period After the elapse of time, a period for transmitting and receiving the feedback signal is provided.

  In the transmitter 10, the feedback receiving unit 140 receives the feedback signal S33 transmitted from the feedback transmitting unit 250, and generates transmission signal control information S16 based on the received feedback signal S33. In this case, the transmission signal control information S16 is information indicating that it is not necessary to adjust the signal strength of the plurality of transmission electrical signals generated by the transmission signal control unit 110.

  As described above, when there is no need to adjust the signal strength of the plurality of transmission electrical signals generated by the transmission signal control unit 110, the signal strength can be maintained as it is by not transmitting the feedback signal S33. I do not care.

  As described above, in the case of the short distance (A) shown in FIGS. 2 and 3, the first optical receiver 210 and the second optical signal S31 and the second optical signal S32 are mixed in a state where the first optical signal S31 and the second optical signal S32 are not mixed. The optical receivers 220 receive only the corresponding first optical signal S31 and second optical signal S32. Therefore, the receiver 20 can identify the first optical signal S31 and the second optical signal S32, respectively, and realizes high-efficiency transmission obtained by parallel transmission.

  On the other hand, FIG. 6B shows a state in which the first optical signal S31 and the second optical signal S32 are mixed, and the first optical receiver 210 and the second optical receiver 220 are connected to the first optical signal S31 and the second optical signal 220, respectively. It is a figure which shows the case where both 2 optical signals S32 are received. That is, this is the case of the intermediate distance (B) shown in FIGS.

  As shown in FIG. 6B (1), the first optical receiver 210 receives an optical signal having a predetermined reception level (α) at t1, t3,..., Tn−1. Then, as shown in FIG. 6B (2), the second optical receiver 220 receives an optical signal having a predetermined reception level (β) at t1, t3,..., Tn−1 (α > Β). That is, the first optical receiver 210 and the second optical receiver 220 receive the first optical signal S31 shown in FIG.

  Further, as shown in FIG. 6B (1), the first optical receiver 210 receives an optical signal having a predetermined reception level (β) at t2, t4,. Then, as shown in FIG. 6B (2), the second optical receiver 220 receives an optical signal having a predetermined reception level (α) at t2, t4,..., Tn (α> β ). That is, the first optical receiver 210 and the second optical receiver 220 receive the second optical signal S32 shown in FIG. 5 (2).

  Then, the first optical receiver 210 converts the received optical signal into a first received electrical signal S21, and the second optical receiver 220 converts the received optical signal into a second received electrical signal S22. To do. Next, the reception signal analysis unit 240 generates reception signal switching information S26 and signal point arrangement information S27 based on the first reception electric signal S21 and the second reception electric signal S22.

  FIG. 7 is a diagram illustrating a method in which the received signal analysis unit 240 generates the signal point arrangement information S27. The first optical receiver 210 receives the first optical signal S31 transmitted from the first optical transmitter 120 during the time “t1” shown in FIG. 6B (1) (reception level = α). The received signal analysis unit 240 is notified as the first received electrical signal S21. Similarly, the second optical receiver 220 receives the first optical signal S31 transmitted from the first optical transmitter 120 during the time “t1” (reception level = β), and receives the second reception. The received signal analysis unit 240 is notified as the electric signal S22. When the first optical transmission unit 120 transmits the first optical signal S31, the reception signal analysis unit 240 receives the reception level 1 of the optical signal received by the first optical reception unit 210, and the second light. The reception level 2 of the optical signal received by the receiving unit 220 is generated as the signal point arrangement information S27. That is, the reception signal analysis unit 240 generates (reception level 1, reception level 2) = (α, β) with (optical signal S31, optical signal S32) = (1,0) in FIG. (# 3).

  Similarly, the first optical receiver 210 receives the second optical signal S32 transmitted from the second optical transmitter 130 during the time “t2” (reception level = β), and receives the first reception. The received signal analysis unit 240 is notified as the electric signal S21. The second optical receiver 220 receives the second optical signal S32 transmitted from the second optical transmitter 130 during the time “t2” (reception level = α), and receives the second received electrical signal S22. To the received signal analyzer 240. That is, the reception signal analysis unit 240 generates (reception level 1, reception level 2) = (β, α) with (optical signal S31, optical signal S32) = (0, 1) in FIG. (# 2).

  This is because the transmitter 10 and the receiver 20 face each other, and the first optical transmitter 120 and the first optical receiver 210, and the second optical transmitter 130 and the second optical receiver 220, This is because there is almost no positional deviation. The distance between the second optical transmitter 130 and the first optical receiver 210 and the distance between the first optical transmitter 120 and the second optical receiver 220 are substantially the same, and the second light The angle at which the second optical signal S32 transmitted from the transmission unit 130 enters the first optical reception unit 210 and the first optical signal S31 transmitted from the first optical transmission unit 120 are the second optical reception. This is because the reception level for receiving the optical signal is substantially the same because the angle incident on the unit 220 is substantially the same.

  Further, the reception signal analyzing unit 240 is configured to generate (optical signal S31, optical signal S32) = (1, 0) and (optical signal S31, optical signal S32) = (0, 1). S31, optical signal S32) = (1, 1), (reception level 1, reception level 2) = (α + β, α + β) is generated (# 4). This is obtained by adding the information of (optical signal S31, optical signal S32) = (1, 0) and (optical signal S31, optical signal S32) = (0, 1).

  Finally, the reception signal analysis unit 240 generates (reception level 1, reception level 2) = (0, 0) with (optical signal S31, optical signal S32) = (0, 0) (# 1).

  As described above, the reception signal analysis unit 240 performs the optical signal reception by the first optical reception unit 210 and the second optical reception unit 220 in the header period of the first optical signal S31 and the second optical signal S32. Based on the strength of the reception level, signal point arrangement information S27 (before feedback) for identifying information included in the first reception electric signal S21 and the second reception electric signal S22 is generated. That is, the signal point arrangement information S27 corresponds to the optical signal patterns of the first optical signal S31 transmitted from the first optical transmission unit 120 and the second optical signal S32 transmitted from the second optical transmission unit 130. This is information indicating the reception levels of the first optical receiver 210 and the second optical receiver 220.

  Here, the magnitudes of α and β are examined. In general, a lens used in an optical receiving unit has a property that the gain increases as the angle at which an optical signal enters the optical receiving unit decreases, and the gain decreases as the angle increases.

  When the first optical reception unit 210 receives the first optical signal S31 transmitted from the first optical transmission unit 120 that faces the first optical reception unit 210, the reception level α is set to the first optical signal S31. When the intensity of the first optical signal S31 transmitted from the optical transmission unit 120 is 1, α ≦ 1.

  On the other hand, when the first optical receiver 210 receives the second optical signal S32 transmitted from the second optical transmitter 130 that does not face the first optical receiver 210, the reception level β is If the intensity of the second optical signal S32 transmitted from the second optical transmitter 130 is 1, β <1. Furthermore, the relationship of α> β always holds. This is because the angle at which the second optical signal S32 is incident on the first optical receiver 210 is larger than the angle at which the first optical signal S31 is incident on the first optical receiver 210.

  For example, in the case of α >> β, among the distances between the signal points of the reception 1 in FIG. (Transmission light 1, transmission light 2) = the distance between adjacent signal points is narrow, such as between (1, 0) and (1, 1), and each signal point is affected by the noise generated in the transmission path or the like. May not be correctly identified. Even when α> β, the distance between signal points between (transmitted light 1, transmitted light 2) = (0, 1) and (1, 0) may be narrowed.

  Furthermore, the optical wireless communication apparatus 100 may implement diversity and identify the first received electrical signal S21 and the second received electrical signal S22 by adding them. In this case, as shown in FIG. 7 (1), the signal point arrangement information S27 is the same as (optical signal S31, optical signal S32) = (0, 1) and (optical signal S31, optical signal in FIG. 7 (1). S32) = (1, 0), and (reception level 1 + reception level 2) = (α + β) (# 2, # 3). That is, if the sum of the first received electrical signal S21 and the second received electrical signal S22 is a received signal S23 (multilevel signal), the first signal transmitted from the transmitter 10 is received from the received signal S23 (multilevel signal). The first optical signal S31 and the second optical signal S32 cannot be identified.

  Therefore, the received signal analysis unit 240 generates feedback information S28. Here, it is assumed that the feedback information S28 is information indicating that the signal intensity of the second optical signal S32 is γ times (γ ≦ 1).

  The feedback transmission unit 250 generates a feedback signal S33 based on the feedback information S28 generated by the reception signal analysis unit 240, and transmits the feedback signal S33 to the transmitter 10.

  In the transmitter 10, the feedback receiving unit 140 receives the feedback signal S33 transmitted from the feedback transmitting unit 250, and generates transmission signal control information S16 based on the received feedback signal S33.

  In the transmission signal control unit 110, the transmission signal selection unit 111 generates a first transmission electric signal S12 and a second transmission electric signal S13 from the transmission data S11. Here, the first transmission electrical signal S12 and the second transmission electrical signal S13 are different signals. Whether the first transmission electrical signal S12 and the second transmission electrical signal S13 are the same signal or different signals is determined according to the transmission signal control information S16. In this case, the first transmission electrical signal S12 and the second transmission electrical signal S13 are different signals.

  Next, the first transmission electric signal S12 and the second transmission electric signal S13 are input to the transmission signal strength adjustment unit 112. Based on the transmission signal control information S16 generated by the feedback receiver 140, the transmission signal strength adjustment unit 112 selects either one or both of the first transmission electrical signal S12 and the second transmission electrical signal S13. The intensity is adjusted and output as the third transmission electric signal S14 and the fourth transmission electric signal S15. Here, the transmission signal strength adjustment unit 112 outputs a fourth transmission electrical signal S15 in which the signal strength of the second transmission electrical signal S13 is adjusted to γ times.

  Then, the third transmission electrical signal S14 and the fourth transmission electrical signal S15 whose signal strengths are adjusted by the transmission signal strength adjustment unit 112 are respectively transmitted by the first optical transmission unit 120 and the second optical transmission unit 130. It is converted into a first optical signal S31 and a second optical signal S32 and transmitted to the receiver 20.

  As described above, after the signal intensity of the second optical signal S32 transmitted from the second optical transmitter 130 is adjusted to γ times, the receiver 20 receives the first optical receiver 210 and the second optical receiver in the receiver 20. The unit 220 receives the first optical signal S31 and the second optical signal S32, and the received signal analysis unit 240 updates the signal point arrangement information S27.

  FIG. 7B is a diagram showing the updated signal point arrangement information S27. Since the signal point arrangement information S27 (after feedback) shown in FIG. 7 (2) is γ ≦ 1, compared to the signal point arrangement information S27 (before feedback) shown in FIG. The distance becomes narrower. Specifically, (optical signal S31, optical signal S32) = distance between signal points of (0,0) and (0,1) and between signal points of (1,0) and (1,1) Distance.

  On the other hand, in the signal point arrangement information S27 (after feedback) shown in FIG. 7 (2), from the sum of the first received electrical signal S21 and the second received electrical signal S22 (received level 1 + received level 2), Signal S31, optical signal S32) = (0, 1) and (optical signal S31, optical signal S32) = (1, 0) can be identified.

In the sum of the first received electrical signal S21 and the second received electrical signal S22 (reception level 1 + reception level 2), the distance between the signal points after feedback becomes larger than the distance between the signal points before feedback. The conditions are as follows.
(1) γ> α / (α + β)
(2) γ> β / (α + β)
(3) γ <1- | α-β | / (α + β)
That is, when γ satisfies the above conditions, the distance between each signal point after feedback can be expanded compared to the distance between each signal point before feedback, even if there is an influence of noise generated in the transmission path, Each signal point can be correctly identified.

  Accordingly, the reception signal analysis unit 240 generates reception signal switching information S26 indicating that the sum of the first reception electrical signal S21 and the second reception electrical signal S22 is the reception signal S23 (multilevel signal).

  The reception signal switching unit 231 calculates the sum of the first reception electric signal S21 and the second reception electric signal S22 based on the reception signal switching information S26 generated by the reception signal analysis unit 240 as a reception signal S23 (multi-level signal). ).

  The reception signal identification unit 232 identifies the reception signal S23 based on the signal point arrangement information S27 (after feedback) generated by the reception signal analysis unit 240, and obtains the first reception data S24 and the second reception data S25. Generate.

  Specifically, a case where γ = 3/4 is described. FIG. 8 is a diagram illustrating the signal point arrangement information S27 generated by the reception signal analysis unit 240 when the transmission level of the second optical signal S32 is adjusted to 3/4 times. In FIG. 8, for the first optical receiver 210, the reception level for receiving the first optical signal S31 transmitted from the first optical transmitter 120 facing the first optical receiver 210 is “40”. The reception level for receiving the second optical signal S32 transmitted from the second optical transmission unit 130 that does not face the first optical reception unit 210 is 1/10 (“4”). Similarly, for the second optical receiver 220, the reception level for receiving the second optical signal S32 is “40”, and the reception level for receiving the first optical signal S31 is 1/10 (“4”). To do.

  As shown in FIG. 8 (1), for example, (transmission light 1, transmission light 2) = between (0,0) and (0,1), and (transmission light 1, transmission light 2) = (1,0). ) And (1, 1), the distance between adjacent signal points is small. Further, in (optical signal S31, optical signal S32) = (0, 1) and (1, 0), (reception level 1 + reception level 2) is the same.

  Therefore, the reception signal analysis unit 240 generates feedback information S28 indicating that the signal intensity of the second optical signal S32 is 3/4 times. As shown in FIG. 8 (2), the distance between signal points is narrower than the distance between signal points before feedback. However, as shown in FIG. 8 (3), (reception level 1 + reception level 2) can be identified even in (optical signal S31, optical signal S32) = (0, 1) and (1, 0). Yes. Furthermore, there is a predetermined distance for the distance between the signal points.

  In this way, if the transmission level of the second optical signal S32 is adjusted to 3/4, the distance between signal points can be increased, and identification errors can be reduced.

  As another specific example, a case where γ = ½ will be described. FIG. 9 is a diagram illustrating signal point arrangement information S27 generated by the reception signal analysis unit 240 when the transmission level of the second optical signal S32 is adjusted to ½. 9, similarly to FIG. 8, for the first optical receiver 210, the reception level for receiving the first optical signal S <b> 31 is “40”, and the reception level for receiving the second optical signal S <b> 32 is 1 / 10 ("4"). For the second optical receiver 220, the reception level for receiving the second optical signal S32 is “40”, and the reception level for receiving the first optical signal S31 is 1/10 (“4”).

  Then, the received signal analyzer 240 generates feedback information S28 indicating that the signal intensity of the second optical signal S32 is halved, and halves the transmission level of the second optical signal S32. adjust. As a result, as shown in FIG. 9 (3), with respect to (reception level 1 + reception level 2), the distances between the signal points are equalized, and further, identification errors can be reduced.

  Next, the case of (C) long distance shown in FIGS. 2 and 3 will be described. (C) In the case of a long distance, unlike the case of (B) the middle distance, the reception level itself detected by the first optical receiver 210 and the second optical receiver 220 is small.

  Although α> β is satisfied, α, β << 1, so even if the optical wireless communication apparatus 100 performs diversity (reception level 1 + reception level 2) as shown in FIGS. ), A predetermined distance between signal points cannot be obtained.

  Therefore, in the case of (C) long distance, the received signal analysis unit 240 provides feedback information S28 indicating that the first optical signal S31 and the second optical signal S32 are the same signal at the maximum level. Generate.

  Then, the feedback transmission unit 250 generates a feedback signal S33 based on the feedback information S28 generated by the reception signal analysis unit 240, and transmits the feedback signal S33 to the transmitter 10.

  In the transmitter 10, the feedback receiver 140 receives the feedback signal S33 transmitted from the feedback transmitter 250, and generates transmission signal control information S16 based on the received feedback signal S33.

  In the transmission signal control unit 110, the transmission signal selection unit 111 generates a first transmission electric signal S12 and a second transmission electric signal S13 that are the same signal from the transmission data S11. Then, the transmission signal strength adjustment unit 112 sets the signal strength to the maximum level for the first transmission electrical signal S12 and the second transmission electrical signal S13 based on the transmission signal control information S16 generated by the feedback reception unit 140. It adjusts and outputs as 3rd transmission electric signal S14 and 4th transmission electric signal S15.

  Then, the third transmission electric signal S14 and the fourth transmission electric signal S15, which are the same signal whose signal intensity is adjusted to the maximum level by the transmission signal intensity adjustment unit 112, are converted into the first optical transmission unit 120 and the second optical transmission unit 120, respectively. Are respectively converted into a first optical signal S31 and a second optical signal S32 and transmitted to the receiver 20.

  Thereby, compared to the case where different optical signals are transmitted from the first optical transmission unit 120 and the second optical transmission unit 130, the receiver 20 receives the same optical signal at the maximum level, The received signal can be identified. That is, the transmission distance can be secured up to a longer distance.

  As described above, according to the optical wireless communication apparatus according to an embodiment of the present invention, even when a plurality of light receiving elements receive optical signals transmitted from a plurality of light emitting elements in a mixed state, By feeding back information for adjusting the intensity of the optical signal transmitted from the light emitting element, the signal identification point is set based on new information obtained by implementing diversity, and thus each received optical signal is identified. be able to. As a result, the receiver can accurately decode the received optical signal. That is, according to the optical wireless communication apparatus according to an embodiment of the present invention, high-efficiency transmission obtained by parallel transmission can be realized.

  Further, according to the optical wireless communication apparatus according to the embodiment of the present invention, even if the optical signal received by the receiver cannot be identified because the reception level of the optical signal detected by the receiver is small. By making the intensity of a plurality of optical signals transmitted from the transmitter the maximum level and feeding back the information to be the same signal, transmission can be realized even at a longer distance.

  In the present embodiment, the receiver 20 transmits the feedback signal S33 once to the transmitter 10 and updates the signal point arrangement information S27 only once. However, the present invention is not limited to this. For example, in the updated signal point arrangement information S27, when the newly obtained distance between signal points is smaller than the previous signal point distance, the receiver 20 transmits the feedback signal S33 to the transmitter 10 again. Further, the signal point arrangement information S27 may be updated. Further, this process may be repeated until a preferable distance between signal points is obtained.

  When the transmission distance between the transmitter 10 and the receiver 20 is small and there is a positional shift, for example, in the first optical receiver 210, the first optical transmitter 120 and the second optical transmitter 130 Both the transmitted first optical signal S31 and second optical signal S32 are received. Then, the second optical receiver 220 may receive only the second optical signal S32 transmitted from the second optical transmitter 130. That is, (A) the short distance shown in FIG. 2 and FIG. 3 is a case where the first optical signal S31 and the second optical signal S32 are mixed. Even in such a case, as shown in the embodiment of the present invention, the receiver transmits the information for adjusting the intensity of the optical signal transmitted from the plurality of light-emitting elements, so that each of the signals is transmitted by the receiver. It goes without saying that the optical signal can be identified.

  In the present embodiment, the headers of the first optical signal S31 and the second optical signal S32 are time-divided and the signal point arrangement is calculated based on the reception level of the optical signal. However, the calculation method is not limited to this. For example, a sine wave signal having a frequency f1 is input to the first optical transmission unit 120 and a sine wave signal having a frequency f2 is simultaneously input to the second optical transmission unit 130 with the same intensity. The received signal analysis unit 240 includes a filter that passes a signal near the frequency f1 (for example, a bandpass filter whose center frequency is f1) and a filter that passes a signal near the frequency f2. By detecting the intensity of the signal that has passed through each filter, the signal point arrangement can be calculated without using the calculation method for time-sharing the header as described above. Thereby, the time for calculating the signal point arrangement can be reduced. In addition, an electrical signal assigned code 1 is input to the first optical transmitter 120, and an electrical signal assigned code 2 is input to the second optical transmitter 130. The received signal analysis unit 240 may calculate the signal point arrangement by performing despreading and calculating the strength of each received electrical signal.

  The optical wireless communication apparatus of the present invention is useful as an infrared communication apparatus that can realize high-speed transmission. Moreover, it can be applied to uses such as visible light communication using a visible light source such as illumination light.

100, 900 Optical wireless communication apparatus 10 Transmitter 20 Receiver 110 Transmission signal control unit 111 Transmission signal selection unit 112 Transmission signal strength adjustment unit 120, 130 Optical transmission unit 140 Feedback reception unit 210, 220 Optical reception unit 230 Reception signal control unit 231 Reception signal switching unit 232 Reception signal identification unit 240 Reception signal analysis unit 250 Feedback transmission unit 500, 950 Information format 501, 951 Header unit 502 Data unit 901, 902 Light emitting unit (optical transmitter)
903, 904 Information terminal 905, 906 Light receiving unit 952 Common information unit 953 Unique information unit 954 Error detection unit S11 Transmission data S12-S15 Transmission electric signal S16 Transmission signal control information S21, S22 Reception electric signal S23 Reception signal S24, S25 Reception data S26 Reception signal switching information S27 Signal point arrangement information S28 Feedback information S31, S32 Optical signal S33 Feedback signal

Claims (6)

An optical wireless communication device that performs data communication between a transmitter and a receiver using a plurality of optical signals,
The transmitter is
A plurality of optical transmitters for converting a plurality of transmission electrical signals into optical signals and transmitting the plurality of optical signals, respectively;
A feedback receiver that receives from the receiver a feedback signal indicating that the plurality of transmission electrical signals are adjusted, and generates transmission signal control information based on the feedback signal;
A transmission signal control unit that adjusts the plurality of transmission electrical signals based on the transmission signal control information;
The receiver
A plurality of optical receivers that receive the plurality of optical signals and convert the plurality of optical signals into received electrical signals, respectively;
Signal point arrangement information indicating reception levels of the plurality of optical reception units corresponding to the optical signal patterns transmitted from the plurality of optical transmission units based on the plurality of received electrical signals converted by the plurality of optical reception units. A received signal analysis unit for generating
A feedback transmission unit that generates the feedback signal based on the signal point arrangement information and transmits the generated feedback signal;
A reception signal control unit that identifies the optical signal pattern transmitted from the plurality of optical transmission units from the reception signal based on the signal point arrangement information, using the sum of the plurality of reception electrical signals as a reception signal; Optical wireless communication device. The feedback signal includes information indicating that signal strengths of the plurality of transmission electrical signals are adjusted so that the optical signal patterns transmitted from the plurality of optical transmission units can be identified from the reception signal,
The optical wireless communication apparatus according to claim 1, wherein the transmission signal control unit includes a transmission signal strength adjustment unit that adjusts signal strengths of the plurality of transmission electrical signals. The feedback signal includes information indicating whether any or all of the plurality of transmission electrical signals are the same signal or different signals,
The transmission signal control unit includes a transmission signal selection unit that selects whether any one or all of the plurality of transmission electric signals are the same signal or different signals. An optical wireless communication device according to claim 1. The reception signal analysis unit outputs the plurality of reception electric signals as they are based on the plurality of reception electric signals converted by the plurality of optical reception units, or receives the sum of the plurality of reception electric signals as a reception signal Generate received signal switching information indicating whether to output as
The received signal controller is
Based on the received signal switching information, the received electrical signal is output as it is, or a received signal switching unit that outputs the sum of the received electrical signals as a received signal;
Received signal identification for identifying a plurality of optical signals transmitted from the plurality of optical transmitters from the plurality of received electrical signals or the received signals output from the received signal switching unit based on the signal point arrangement information The optical wireless communication apparatus according to claim 1, further comprising: A receiver that receives a plurality of optical signals transmitted from a plurality of optical transmitters of a transmitter,
A plurality of optical receivers that receive a plurality of optical signals transmitted from a plurality of optical transmitters of the transmitter and convert the plurality of optical signals into received electrical signals, respectively;
A signal indicating reception levels of the plurality of optical reception units corresponding to the optical signal patterns transmitted from the plurality of optical transmission units of the transmitter based on the plurality of received electrical signals converted by the plurality of optical reception units. A received signal analyzer for generating point arrangement information;
A feedback transmission unit that generates a feedback signal indicating that a plurality of optical signals transmitted from the plurality of optical transmission units of the transmitter are adjusted based on the signal point arrangement information, and transmits the generated feedback signal; ,
A reception signal control unit that identifies the optical signal pattern transmitted from the plurality of optical transmission units of the transmitter from the reception signal based on the signal point arrangement information, using the sum of the plurality of reception electrical signals as a reception signal And a receiver. A reception method executed by a receiver that receives a plurality of optical signals transmitted from a plurality of optical transmission units of a transmitter by a plurality of optical reception units,
Receiving a plurality of optical signals transmitted from a plurality of optical transmission units of the transmitter at the plurality of optical receiving units, and converting the plurality of optical signals into received electrical signals, respectively;
Signal point arrangement information indicating reception levels of the plurality of optical reception units with respect to an optical signal pattern transmitted from the plurality of optical transmission units of the transmitter based on the plurality of reception electrical signals converted in the optical reception step. A received signal analysis step to generate;
A feedback transmission step of generating a feedback signal indicating adjusting a plurality of optical signals transmitted from a plurality of optical transmission units of the transmitter based on the signal point arrangement information, and transmitting the generated feedback signal; ,
A received signal control step of identifying an optical signal pattern transmitted from a plurality of optical transmitters of the transmitter from the received signal based on the signal point arrangement information using a sum of the plurality of received electrical signals as a received signal Including a receiving method.

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