JP2019022048A - Spatial optical communication system and method for transmitting and receiving data in spatial optical communication system - Google Patents

Abstract

To secure a communication path in space optical communication over a wide range such that stable communication can be performed.SOLUTION: A spatial optical communication system includes a space optical transceiver 211 configured to be movable, a terminal-side electronic device 210 connected to the space optical transceiver 211 so as to transmit and receive data, a plurality of distributed and arranged spatial optical transceivers 221A to 221C, a host-side electronic device 220 for sending and receiving data, and a signal selector 300 connected thereto and select the spatial optical transceivers 221A to 221C, an IDLE signal is always allowed to flow through an optical transmission line between the spatial optical transceiver 211 and the spatial optical transceivers 221A to 221C, one of the spatial optical transceiver 221A to 221C whose intensity is the maximum is selected, and the data is transmitted and received through the selected transmitters/receivers.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a spatial optical communication system that performs communication by emitting light directly into space and a data transmission / reception method thereof.

  An example of a conventional spatial optical communication system is shown in FIGS. 9 and 10, reference numeral 110 denotes a first electronic device such as a tablet PC (personal computer), and 111 denotes light emission that is connected to the first electronic device 110 and converts an electrical signal such as data into an optical signal. It is a spatial light transceiver having an element and a light receiving element that converts a received optical signal into an electric signal.

  Reference numeral 120 denotes a second electronic device such as a notebook PC, and 121 denotes a light-emitting element that is connected to the second electronic device 120 and converts an electrical signal such as data into an optical signal, and the received optical signal is an electrical signal. This is a spatial light transmitter / receiver having a light receiving element for converting into a light.

  The first electronic device 110 and the spatial light transceiver 111 constitute a first communication device, and the second electronic device 120 and the spatial light transceiver 121 constitute a second communication device.

  9 and 10, as an example, an irradiation angle (an angle at which light is spread, which is an effective angle of the light emitting element of the spatial light transmitter / receiver 111, and generally the luminous intensity value is 1/2 or 1/10 of the maximum luminous intensity. And a half-value angle (an angle at which the relative sensitivity is halved), which is an effective angle of the light receiving element of the spatial light transceiver 121.

  In the case of optical communication, communication is not possible unless the transmitted / received light is within the effective angle range of the light emitting element and the light receiving element. As shown in FIG. 10, the first electronic device 110 and the spatial light transceiver are used. For example, communication cannot be performed if the optical system 111 deviates from the light transmission / reception range due to movement, for example. This is because the linearity of the light is extremely strong, and if the light receiving range (half-value angle) of the light receiving element is out of the range, the sensitivity is lowered and communication is impossible.

  As a method of widening this range, a method of increasing optical transmission power (light intensity) can be considered.

  However, increasing the optical transmission power means that the received optical power is reduced in inverse proportion to the square of the distance, so that it is necessary to increase the optical transmission power to communicate far away over a wide range. When determining the distance, it becomes difficult to realize.

  Conversely, there is a method for increasing the sensitivity, but in this case, a highly sensitive and complicated receiving circuit is used, which is also difficult to realize.

  From the above, in the case of spatial light transmission, as a method that is usually used, a method is generally used in which communication is performed by narrowing the optical axis with a lens or the like and accurately matching the other station. If the optical axis is reduced by a lens or the like, the light reaches far, but as a demerit, the light receiving range (light receiving angle) is narrowed.

  For this reason, when the conventional method is applied, it is necessary to always aim the optical axis toward the other station, and as a result, it is difficult to apply when the other party moves, such as in a portable terminal.

  As a conventional example, Japanese Patent Application Laid-Open No. H10-228707 describes a method of communicating over a wide range by providing a plurality of light emitting / receiving units in a data processing device and switching between them to transmit and receive.

  Patent Document 2 describes a method in which a plurality of light receiving units are provided, and a signal in which a signal change occurs most quickly among signals received by the respective light receiving units is described.

  Further, Patent Document 3 describes that a light receiving unit composed of an optical sensor and a light receiving lens is used as a unit unit, and an arbitrary number of unit units are combined to expand a light receiving range of a transmitting / receiving element.

Japanese Patent Laid-Open No. 10-98435 Japanese Patent No. 4920329 JP-A-5-11150

  In the communication system described in Patent Document 1, since a computer is used and controlled by a CPU, ROM, RAM, etc., the apparatus becomes very complicated. In addition, since software control is performed by the CPU, there is a problem that the effective transmission speed is also slowed down.

  In the method described in Patent Document 2, as a precondition, the transmitter / receiver that has changed the earliest among a plurality of transmitters / receivers is assumed to be closest to the partner station, and the reception signal of the closest transmitter / receiver is one. It is assumed that it is the strongest, and it is presumed that the method of judging that it is effective to select this signal.

  Here, a problem when the method described in Patent Document 2 is applied to the configuration diagram (overhead view of FIG. 8) of the spatial optical communication system according to the embodiment of the present invention will be described. In FIG. 8, 211 is a spatial light transmitter / receiver connected to the terminal-side electronic device 210 which is the first electronic device.

  221A to 221C are spatial light transmitters / receivers that are distributed in each of the nodes A to C, which are a plurality of communication points, and are connected to the host-side electronic device 220, which is the second electronic device, via the signal selector 300. .

  Optical signals are transmitted and received between the spatial optical transceiver 211 on the terminal side and the spatial optical transceivers 221A to 221C on the host side, but the distance between the spatial optical transceiver 221B and the spatial optical transceiver 211 at the node B When LB is closest, the signal that changes first is considered to be a signal from node B. For this reason, when the method of Patent Document 2 is applied, it is determined that the received signal from the node B is the strongest.

  However, when the obstruction 400 such as a foliage plant is in the optical transmission path between the spatial light transceivers 211-221B, the reception level may be greatly reduced. In this way, a situation in which the signal that arrives first cannot always be determined as the optimal signal can occur sufficiently even in normal operation.

  In addition to this example, if the signal coming later is larger due to reflection by the glass, it is possible that the signal that has been selected is large. There is a possibility of covering, it may not work well.

  Further, in the configuration described in Patent Document 3, it is possible to deal with a case where the light receiving range deviates as described in FIG. 10 or a case where there is an obstruction in the light transmission path as described in FIG. Is not specified.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to provide a spatial optical communication system and a data transmission / reception method thereof that can secure a wide range of communication paths in spatial optical communication and perform stable communication. .

The spatial optical communication system according to claim 1 for solving the above-mentioned problem is as follows.
A first communication apparatus having an optical transceiver configured to be movable and a first electronic device connected to the optical transceiver for transmitting and receiving data, a plurality of optical transceivers arranged in a distributed manner, and data Communication with a second electronic device that transmits / receives data and a second communication device that has signal selection means connected to the second electronic device to select the plurality of dispersed optical transceivers A spatial optical communication system,
The first electronic device has a function of transmitting a dummy signal when there is no transmission data,
The optical transmitter / receiver of the first communication device includes an optical transmitter that converts an electrical signal to be transmitted into an optical signal, an optical receiver that receives and converts the optical signal into an electrical signal, and an optical receiver. An AGC amplifier that holds the peak value of the converted electrical signal and performs automatic gain adjustment;
The plurality of transceivers of the second communication device includes: an optical transmission unit that converts an electrical signal to be transmitted into an optical signal and transmits the optical signal; an optical reception unit that receives and converts the optical signal into an electrical signal; and an optical reception unit An AGC amplifier that holds the peak value of the electrical signal converted in step (a) and performs automatic gain adjustment, and a reception level detector that detects the level of the electrical signal converted by the optical receiver,
The signal selection means includes
When there is no transmission data from the second electronic device to the plurality of optically arranged optical transceivers, a dummy signal is transmitted as a transmission signal, and a received signal from the optical transceiver to the second electronic device It has a function to delete dummy signals,
A transmission changeover switch for switching transmission of a transmission electrical signal path or a dummy signal from the second electronic device to any one of the plurality of optically arranged optical transceivers, and a second from each of the optical transceivers. A reception changeover switch for switching a reception electric signal path to the electronic device;
A maximum reception level detection unit for detecting an optical transmitter / receiver having a maximum reception level by obtaining a maximum value of an electric signal level detected by each reception level detection unit of the plurality of optically arranged optical transceivers distributed;
At the time of linking from the first communication device to the second communication device, the reception changeover switch is switched to the reception signal path on the optical transceiver side of the maximum reception level detected by the maximum reception level detector, Switch the transmission selector switch to the dummy signal transmission side,
At the time of linking from the second communication device to the first communication device, the reception changeover switch is switched to the reception signal path on the optical transceiver side of the maximum reception level detected by the maximum reception level detection unit, The transmission changeover switch is switched to the transmission side of the dummy signal when there is no transmission data from the second electronic device, and the maximum detected by the maximum reception level detection unit during the period when there is transmission data from the second electronic device. A switch control unit that performs control to switch to a transmission signal path on the optical transceiver side of the reception level;
It is provided with.

The data transmission / reception method of the spatial optical communication system according to claim 2 is:
A first communication apparatus having an optical transceiver configured to be movable and a first electronic device connected to the optical transceiver for transmitting and receiving data, a plurality of optical transceivers arranged in a distributed manner, and data Communication with a second electronic device that transmits / receives data and a second communication device that has signal selection means connected to the second electronic device to select the plurality of dispersed optical transceivers A data transmission / reception method for a spatial light communication system, comprising:
Each of the optical transceivers of the first communication device and the second communication device includes an AGC amplifier that performs automatic gain adjustment by holding a peak value of an electric signal obtained by opto-electric conversion of the received optical signal,
Each optical transceiver of the second communication device includes a reception level detection unit that detects a level of an electrical signal obtained by photoelectrically converting the received optical signal,
The signal selection means includes a transmission changeover switch for switching transmission of a transmission electrical signal path or a dummy signal from the second electronic device to any of the plurality of optically arranged optical transceivers, and each of the optical transceivers. A reception changeover switch that switches a reception electrical signal path from any one to the second electronic device,
The first electronic device transmitting a dummy signal when there is no transmission data;
The signal selection means sending a dummy signal as a transmission signal when there is no transmission data from the second electronic device to the plurality of optically arranged optical transceivers;
The signal selecting means deleting a dummy signal in the received signal from each optical transceiver to the second electronic device;
The maximum reception level detection unit provided in the signal selection means obtains the maximum value of the electric signal level detected by each reception level detection unit of the plurality of optically arranged optical transceivers, and outputs the light of the maximum reception level. A maximum reception level detection step for detecting a transceiver;
When the switch control unit provided in the signal selection unit links from the first communication device to the second communication device, the switch of the maximum reception level detected by the maximum reception level detection unit is set to the reception changeover switch. Switching to the reception signal path on the optical transceiver side, switching the transmission switch to the transmission side of the dummy signal;
When the switch control unit is linked from the second communication device to the first communication device, the reception change-over switch is set to the reception signal on the optical transceiver side of the maximum reception level detected by the maximum reception level detection unit. Switching to a path, switching the transmission switch to a dummy signal transmission side during a period when there is no transmission data from the second electronic device, and the maximum reception level detecting unit during a period when there is transmission data from the second electronic device. Switching to the transmission signal path on the optical transceiver side of the maximum reception level detected in
It is provided with.

(1) According to the first and second aspects of the present invention, since the plurality of optical transceivers of the second communication device are distributed, the communication path with the movable first communication device is wide. Can be secured over a range.

  Even if an obstacle causing attenuation of an optical signal is present in the path between the optical transceiver of the first communication device and any of the plurality of optical transceivers of the second communication device, the plurality of optical transceivers If there is any one of the routes that can be communicated, communication can be performed using the route.

  In addition, since a dummy signal is always transmitted even when there is no transmission data, an AGC amplifier necessary for spatial optical communication can be stably operated to ensure gain, and reception can always be performed with an optimum gain. .

  In addition, since the maximum reception level detecting unit detects the optical transmitter / receiver having the maximum reception level on the second communication apparatus side, transmission / reception can always be performed via the optical transmitter / receiver having the maximum reception level.

  In addition, it is possible to control a plurality of communication points, that is, a plurality of optical transceivers arranged in a distributed manner, with a relatively simple configuration without requiring software processing by a CPU or the like.

1 is a configuration diagram of a spatial light communication system according to an example embodiment of the present invention. 1 illustrates each part of the system of FIG. 1, (a) is a configuration diagram of a spatial optical transceiver on the terminal side, (b) is a configuration diagram of a spatial optical transceiver on the host side, and (c) is a configuration diagram of a signal selector. The block diagram which shows the connection state of the space side optical transmitter / receiver and signal selector of the host side in the system of FIG. 1, and the detail of a signal selector. The time chart which shows the operation | movement at the time of UPLINK in the example of embodiment of this invention. The time chart which shows the operation | movement at the time of DOWNLINK in the example of embodiment of this invention. The time chart which shows IDLE transmission / reception timing and data transmission / reception timing in case the signal which arrives in the shortest in the example embodiment of this invention is the strongest signal. The time chart which shows IDLE transmission / reception timing and data transmission / reception timing in case the signal which arrives in the shortest in the example embodiment of this invention is not the strongest signal. In the embodiment example of this invention, a system block diagram (overhead view) in case an obstruction exists in an optical transmission path | route. The block diagram of the conventional space optical communication system. Explanatory drawing showing a mode that the transmission / reception range of light deviated in the system of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. FIG. 1 shows a configuration of a spatial light communication system according to the present embodiment, 210 is a terminal-side electronic device (first electronic device) such as a tablet PC (personal computer), and 211 is a terminal-side electronic device. A spatial light transceiver that is connected to 210 and has a light emitting element that converts an electrical signal such as data into an optical signal and a light receiving element that converts a received optical signal into an electrical signal. The terminal-side electronic device 210 and the spatial light transmitter / receiver 211 are portable and movable, and constitute a first communication device.

  Reference numeral 220 denotes a host-side electronic device (second electronic device) such as a notebook PC, and 221A to 221C are distributed and arranged in nodes A to C, which are a plurality of communication points on the host-side electronic device 220 side, respectively. A spatial light transceiver having a light emitting element that converts an electrical signal such as an optical signal and a light receiving element that converts a received optical signal into an electrical signal.

  Note that the number of spatial light transmitters / receivers (221) to be distributed is not limited to three, but may be a plurality of other numbers.

  A function 300 is connected to the host-side electronic device 220 and transmits a dummy signal, which will be described later, as a transmission signal when there is no transmission data, and deletes a dummy signal in the reception signal. A transmission switch for switching transmission of a transmission electrical signal path or a dummy signal to any of the optical transceivers 221A to 221C, and a reception electrical signal path from any of the spatial light transceivers 221A to 221C to the host-side electronic device 220 are switched. A control function for detecting a spatial light transmitter / receiver having the maximum reception level among the reception switch and the spatial light transmitter / receivers 221A to 221C, and switching the transmission switch and the reception switch to the detected spatial light transmitter / receiver side having the maximum reception level. And so on.

  The host-side electronic device 220, the spatial light transmitters / receivers 221A to 221C, and the signal selector 300 are fixedly arranged to constitute a second communication device.

  The spatial light transceivers 211, 221A to 221C and the signal selector 300 in FIG. 1 are configured as shown in FIG.

  In FIG. 2A showing the configuration of the spatial light transceiver 211 on the terminal side (for example, the tablet PC side), reference numeral 10 denotes a photodiode (light receiving element) that converts a received optical signal into an electric signal (current). The output signal of the photodiode 10 is converted into a voltage by the receiving amplifier 11 and amplified.

  An AGC amplifier 12 receives the output voltage of the reception amplifier 11 and holds the peak value of the voltage to perform automatic gain adjustment. The output voltage (reception signal) of the AGC amplifier 12 is compared with a predetermined threshold value in the control unit 13, and a signal equal to or higher than the threshold value is derived as a demodulation result to the terminal-side electronic device 210 (not shown) via the reception amplifier 14 and the connector 20. Is done.

  When a data signal is input from the terminal-side electronic device 210 to the control unit 13 via the connector 20 and the transmission amplifier 15, the control unit 13 drives the light emitting diode (light emitting element) 17 via the LED driver 16, thereby The data signal is converted into an optical signal by the light emitting diode 17 and transmitted to the space.

  The terminal-side electronic device 210 has a function of transmitting an IDLE signal (idle state signal) that is a dummy signal instead of the transmission data when there is no transmission data.

  FIG. 2B shows one of three spatial optical transceivers 221A to 221C that are distributed on the host side and in which the connector 20 is connected to the signal selector 300. FIG. The same parts are indicated by the same reference numerals.

  2 (b) is different from FIG. 2 (a) in that reception level detection for detecting the light reception level from the output of the reception amplifier 11 using the control unit 23 having the same function instead of the control unit 13. 2 is provided, and the detected reception level detection signal is sent to the signal selector 300 side via the control unit 23, the buffer 24, and the connector 20, and the other parts are the same as in FIG. It is configured.

  In FIG. 2C showing the signal selector 300, 20A to 20C are connectors connected to the connectors 20 of the spatial light transceivers 221A to 221C, respectively, and 20 is connected to the host-side electronic device 220. Connector.

  Transmission amplifiers 15a to 15c for amplifying transmission signals from the signal control unit 30 to the connectors 20A to 20C, reception amplifiers 14a to 14c for amplifying reception signals from the connectors 20A to 20C to the signal control unit 30, and reception levels Buffers 34a to 34c for buffering the detection signals are provided.

  A reception amplifier 14 and a transmission amplifier 15 are provided between the connector 20 and the signal control unit 30.

  The signal control unit 30 is configured as shown in FIG. 3, the same parts as those in FIG. 2 are denoted by the same reference numerals.

  In FIG. 3, when there is no transmission data from the host-side electronic device 220 to the terminal-side electronic device 210, the signal control unit 30 of the signal selector 300 replaces the transmission data with an IDLE signal (idle signal) that is a dummy signal. The IDLE signal is generated by the IDLE generating unit 31.

  In the present embodiment example, it is assumed that in communication between the host and the terminal (between 220 and 210), data is not continuously communicated and there is a time during which data is not sent. Since the time during which this data is not sent remains as it is, there is no signal, so a signal which is an IDLE signal, which is not information, is sent.

  As described above, since the IDLE signal is also transmitted from the terminal-side electronic device 210 when there is no transmission data, the IDLE signal always flows through the optical transmission line except when information (data) is transmitted.

  Reference numeral 32 denotes a host interface (HOST I / F) that controls communication, and a transmission changeover switch, which will be described later, with a transmission signal HOSTTX introduced from the host-side electronic device 220 via the connector 20 and the transmission amplifier 15 as a transmission signal TX. The IDLE signal is deleted from the function to send to TXSW1 to TXSW3 and the reception signal RX introduced from the reception changeover switch RXSW described later, and the reception signal HOSTRX is sent to the host-side electronic device 220 via the reception amplifier 14 and the connector 20. A transmission function, and a function of checking the presence / absence of transmission data from the host-side electronic device 220 and generating a transmission data presence signal TXENB when the transmission data is present.

  Transmission changeover switches TXSW1 to TXSW3 and a reception changeover switch RXSW are provided between the host interface 32, the reception amplifiers 14a to 14c, the transmission amplifiers 15a to 15c, and the buffers 34a to 34c.

  TXSW1 is a transmission switch for node A, and switches (selects one) an IDLE signal from the IDLE generation unit 31, a transmission signal TX from the host interface 32, or transmission stop, and selects a transmission signal TXA. To the transmission amplifier 15a.

  TXSW2 is a transmission switch for Node B, and switches (selects one) an IDLE signal from the IDLE generation unit 31, a transmission signal TX from the host interface 32, or transmission stop, and selects a transmission signal TXB. To the transmission amplifier 15b.

  TXSW3 is a transmission switch for node C, and switches (selects one) an IDLE signal from the IDLE generation unit 31, a transmission signal TX from the host interface 32, or transmission stop, and selects a transmission signal TXC. To the transmission amplifier 15c.

  The reception changeover switch RXSW switches (selects one of) the reception signals RXA to RXC amplified by the reception amplifiers 14a to 14c and inputs them to the host interface 32 as the reception signal RX.

  35 calculates the maximum value (maximum received signal strength) of the received signal levels LEVELA to LEVELC detected by the received level detector 22 of each of the spatial light transceivers 221A to 221C input via the buffers 34a to 34c. The maximum reception level detection unit detects a spatial light transmitter / receiver having a maximum reception level and outputs a maximum reception level detection signal MAXSEL.

  36 receives the maximum reception level detection signal MAXSEL from the maximum reception level detection unit 35 and the transmission data present signal TXENB emitted from the host interface 32, and transmits transmission switch control signals TXSW1CONT, TXSW2CONT, TXSW3CONT, and reception switch control. A switch control unit that generates and outputs a signal RXSWCONT.

  The switch control unit 36 transmits the reception changeover switch RXSW to the spatial light transmission / reception of the maximum reception level detected by the maximum reception level detection unit 35 during the link (UPLINK) from the terminal side electronic device 210 to the host side electronic device 220. Switch to the reception signal path (one of RXA to RXC) on the receiver side (by the reception switch control signal RXSWCONT), and switch the transmission switch TXSW1 to switch TXSW3 to the IDLE signal side from the IDLE generator 31 (transmission switching) Switch control signals TXSW1CONT, TXSW2CONT, TXSW3CONT).

  Further, the switch control unit 36 sets the reception changeover switch RXSW to the maximum reception level detected by the maximum reception level detection unit 35 at the time of DOWNLINK from the host side electronic device 220 to the terminal side electronic device 210. Switching to the reception signal path (any one of RXA to RXC) on the spatial light transmitter / receiver side (by the control signal RXSWCONT), setting the transmission switch TXSWT1 to XSW3 to a period when there is no transmission data from the host-side electronic device 220. Switching to the IDLE signal side from the IDLE generation unit 31 (by the control signals TXSW1CONT, TXSW2CONT, TXSW3CONT).

  Further, during a period in which there is transmission data from the host-side electronic device 220, control is performed to switch to the transmission signal path on the spatial light transceiver side of the maximum reception level detected by the maximum reception level detector 35.

  That is, among the transmission switch for node A to node C, the transmission signal switch from the host interface 32 is selected at the transmission switch (TXSW1 to TXSW3) of the node having the maximum reception level, and other transmissions are performed. The changeover switch selects stop (by the control signals TXSW1CONT, TXSW2CONT, TXSW3CONT).

  Next, the operation of the apparatus configured as described above will be described with reference to the time charts of FIGS. FIG. 4 is a time chart showing reception timing on the host side when data is sent from the terminal side electronic device 210 to the host side electronic device 220 (UPLINK).

  In FIG. 4, (a) shows the signal of each part of the node A, (b) shows the signal of each part of the node B, (c) shows the signal of each part of the node C, and (d) shows the signal selector. The signal of each part of the signal control part 30 of 300 is shown, (e) has shown the IDLE signal which flows into the optical transmission line between the spatial light transmitter-receiver 211 and the spatial light transmitter-receivers 221A-221C.

  FIG. 4 shows the reception timing on the host side, and the transmission changeover switches TXSW1 to TXSW3 always select the IDLE signal by the transmission changeover switch control signals TXSW1CONT, TXSW2CONT, and TXSW3CONT in FIG.

  Therefore, the transmission signals TXA, TXB, TXC are IDLE as shown in FIGS.

  Also, the reception level detection signals LEVELA to LEVELC of the reception level detection units 22 of the spatial light transceivers 221A to 221C are signals indicating the reception strengths of the nodes A to C as shown in FIGS. It has become.

  In this example, the magnitudes of the received strengths are assumed to be LEVELA> LEVELVE> LEVELC.

  As shown in FIGS. 4A to 4C, the reception signals RXA to RXC at the nodes A to C receive the IDLE signal from the terminal-side electronic device 210 except during the data transmission period (time t1 to t2). However, in the data transmission period (time t1 to t2), the data A to C respectively correspond.

  Note that the propagation delay difference in FIGS. 4A to 4C represents a difference in communication time between one spatial light transceiver 211 and a plurality of spatial light transceivers 221A to 221C. This difference in propagation delay occurs because the delay times are not equal between the spatial optical transceivers of each node.

  Since there is no transmission data (HOSTTX in FIG. 4D) input to the host interface 32 (HOSTTX is low level), the transmission data present signal TXENB (FIG. 4D) issued from the host interface 32 is low level. It has become.

  In FIG. 4D, the maximum reception level detection signal MAXSEL output from the maximum reception level detection unit 35 is a signal indicating LEVELA of the node A having the maximum reception level.

  Therefore, the reception changeover switch RXSW selects the reception signal RXA based on the reception changeover switch signal RXSWCONT output from the switch control unit 36. Therefore, the reception signal HOSTRX output from the host interface 32 to the reception amplifier 14 passes through the reception signal RXA (the spatial optical transceiver 221A of the node A) in the data transmission period (time t1 to t2) from the terminal-side electronic device 210. The data A) is transmitted to the host-side electronic device 220.

  In this way, the reception signal RXA of the node A that is the maximum reception level is relayed to the host-side electronic device 220 at UPLINK.

  In a period other than the data transmission period (time t1 to time t2), the reception signal RXA selected by the reception changeover switch RXSW includes an IDLE signal as indicated by RXA in FIG. Since it is deleted by the IDLE deletion function, HOSTRX is “no signal”.

  Next, FIG. 5 is a time chart showing the transmission timing on the host side when data is sent from the host side electronic device 220 to the terminal side electronic device 210 (during DOWNLINK).

  In FIG. 5, (a) shows the signal of each part of the node A, (b) shows the signal of each part of the node B, (c) shows the signal of each part of the node C, and (d) shows the signal selector. The signal of each part of the signal control part 30 of 300 is shown, (e) has shown the IDLE signal which flows into the optical transmission line between the spatial light transmitter-receiver 211 and the spatial light transmitter-receivers 221A-221C.

  FIG. 5 shows the transmission timing on the host side. In FIGS. 5A to 5C, the reception signals RXA to RXC are all IDLE signals from the terminal-side electronic device 211, and each spatial light transmission / reception is performed. The reception level detection signals LEVELA to LEVELC of the reception level detectors 22 of the devices 221A to 221C are the reception strengths of the nodes A to C, respectively.

  In FIG. 5D, the reception signal HOSTRX output from the host interface 32 is no signal because it is a transmission timing, and the maximum reception level detection signal MAXSEL is the LEVELA of the node A at the maximum reception level. Is output.

  Therefore, the reception changeover switch RXSW selects the reception signal RXA of the node A by the reception changeover switch control signal RXSWCONT.

The transmission signal HOSTTX output from the transmission amplifier 15 to the host interface 32 is a non-signal during a period other than the data transmission period from time t1 to t2, and receives transmission data from the host-side electronic device 220 at time t1 to t2.
The transmission data present signal TXENB output from the host interface 32 becomes high level during the data transmission period from time t1 to t2.

  Therefore, the transmission changeover switch control signal TXSW1CONT output from the switch control unit 36 is a signal for selecting the transmission signal TX from the host interface 32.

  As a result, in the data transmission period from time t1 to t2, the transmission switch TXSW1 selects the TX side ("data transmission" of TXA in FIG. 5A), and the transmission data is output as the transmission signal TXA.

  The transmission changeover switch control signals TXSW2CONT and TXSW3CONT are both signals for selecting transmission stop. As a result, in the data transmission period from time t1 to t2, the transmission change-over switches TXSW2 and TXSW3 select the transmission stop side ("transmission stop" of TXB and TXC in FIGS. 5B and 5C), and the nodes B and C The side does not transmit.

  In the period other than the data transmission period, since IDLE is selected by the transmission switch control signals TXSW1CONT to TXSW3CONT, the transmission signals TXA to TXC are IDLE signals.

  As described above, the reason why transmission is performed only from the node on the maximum reception level side among the plurality of nodes A to C is that, as shown in an IDLE signal in FIG. This is because a sufficient interval is secured and the pattern can be transmitted simultaneously. However, in the case of data transmission, it is necessary to narrow the bit interval and simultaneous transmission is impossible. The bit interval means the transmission rate. If the bit interval is increased, the transmission rate is lowered. Since the IDLE signal is not information, there is no problem even if the communication speed is low. On the other hand, in data transmission, it is necessary to increase the communication speed, and the bit interval cannot be increased.

  Next, IDLE transmission / reception timing and data transmission / reception timing in transmission processing from a plurality of nodes will be described with reference to FIG. 6A to 6E show IDLE transmission / reception timings, FIG. 6A shows each transmission signal of the spatial optical transceivers 221A to 22C on the host side, and FIG. 6B shows the spatial optical transceiver 211 on the terminal side. (C) shows the output signal of the AGC amplifier 12, (d) shows the AGC voltage, and (e) shows the demodulation result.

  6 (f) to 6 (i) are data transmission / reception timings, (f) shows each transmission signal of the spatial light transceivers 221 A to 22 C on the host side, and (g) shows an output signal of the AGC amplifier 12. , (H) indicates the AGC voltage, and (i) indicates the demodulation result.

  In FIG. 6, the IDLE signal is simultaneously transmitted from all nodes (TXA to TXC in FIG. 6A). This is because the terminal-side electronic device 210 to be a communication partner, for example, the tablet PC side is portable and the position cannot be specified, so it is necessary to transmit light from all nodes and receive it on the tablet PC side. .

In a system such as space optical communication, the reception power of an optical signal decreases in inverse proportion to the square of the distance, so the use of an AGC amplifier is an absolute condition. Also, in space optical communication, burst transmission (communication) is extremely difficult, and in order to operate the AGC amplifier stably, it is necessary to continue sending dummy data such as an IDLE signal even when there is no transmission data. Transmission is a transmission method in which transmission is performed only when there is transmission data, and transmission is not performed when there is no data. When the level fluctuation of the received signal is severe (the dynamic range is wide), the AGC response time becomes very long, and it takes time until the AGC amplifier follows each time burst communication is performed.

  As a result, even if an AGC amplifier having a wide dynamic range is made, it takes time for the AGC amplifier to follow each reception, and transmission efficiency does not increase.

  For these reasons, it is difficult to make a practical AGC amplifier with a wide dynamic range and compatible with burst communication. Therefore, the present embodiment employs a method of sending an IDLE signal when there is no transmission data, not burst transmission.

  As shown in FIG. 6B, the transmission signals TXA to TXC (IDLE signals) from the nodes A to C received by the terminal-side electronic device 210 have a difference in inter-node propagation delay. The example shows the case where the shortest arrival signal (TXA) is the maximum reception level, and the output of the AGC amplifier 12 has a stepped waveform as shown in FIG.

  Note that the signal reception level in FIG. 6B is TXA> TXB> TXC, and the distance from each node A to C to the terminal-side electronic device 210 (tablet PC, etc.) is also assumed to be TXC> TXB> TXA. To do.

  In this embodiment, since the pulse interval of the IDLE signal is sufficiently long, the AGC amplifier 12 corresponds to the signal of the maximum reception level (TXA in this example) by peak hold as shown in FIG. Since the AGC control is applied, the AGC amplifier 12 is always in a receivable state with an optimum gain (a state in which the gain is adjusted to the signal of the maximum signal level).

  This also means that the AGC always follows the signal of the maximum received signal level, and that the AGC amplifier is not saturated at any timing. In other words, this indicates that a signal having the maximum received signal level is always received.

  In this example, the IDLE signal is transmitted as a single pulse with an IDLE cycle. This IDLE signal is an example, and other bit patterns can be used as long as it is a pattern that does not cause a problem even when a plurality of nodes are transmitted simultaneously.

  The AGC voltage shown in FIG. 6D is compared with a predetermined threshold (1.0 in this example) by the control unit 13, and the determination result is the demodulation result shown in FIG.

  This demodulation result is a demodulation result of the IDLE signal and is a signal that is not received as data on the tablet terminal (terminal-side electronic device) side. Therefore, there is no problem even if the waveform width increases.

In the data transmission / reception period after time t _DATA in FIGS. 6F to 6I, only TXA is selected as shown in FIG. 6F, and transmission of TXB and TXC is stopped. This is because, unlike the IDLE pattern, data transmission / reception increases the transmission rate, so that the bit interval is narrowed. As a result, if each node transmits simultaneously, interference occurs on the terminal-side electronic device side.

  As described above, when data is transmitted, transmission is switched to TXA-only transmission as shown in FIG. 6 (f). Therefore, the terminal-side electronic device 210 has no problem with data (DATA as shown in FIGS. 6 (g), (h), (i). ) Reception is performed.

  Since the IDLE signal has no information, it is deleted by the host interface 32 mounted on the signal control unit 30 of the signal selector 300 in FIG.

  At this time, as shown by the AGC voltage in FIG. 6 (h), since the AGC amplifier 12 performs the peak hold type AGC operation, it always follows the reception signal of the maximum level. In this case, TXA is the maximum reception signal. Yes, the AGC amplifier 12 follows TXA. This means that a TXA data signal can be received from the head without any problem.

  With the above operation, the terminal-side electronic device 210, for example, the tablet PC side, can stably receive data (DATA) signals from the transmission signals of a plurality of nodes.

  In the present embodiment example, reception level information (LEVELA to LEVELC) from the nodes A to C is used as a method of selecting the optimum spatial light transceivers (221A to 221C) of the node for one spatial light transceiver 211. Yes.

  As shown in FIG. 9 and FIG. 10, when the sensitivity ranges of the spatial light transmitter / receiver are set in the same direction, the magnitudes of the reception level information LEVELA to LEVELLC are transmitted to the terminal-side electronic device 210 side on the contrary. This is considered to be proportional to the magnitude of the received signal strength.

  This is because the optical signal has a bidirectional relationship, and if the intensity is maximum when transmitted from one side, it can be expected that the intensity is maximum even when transmitted from the opposite side.

  For the above reasons, the optimum combination of the nodes A to C and the terminal-side electronic device 210 (tablet terminal or the like) can be determined by using the reception level information.

  Next, the operation when the signal that arrives in the shortest time is not the strongest signal will be described with reference to the time chart of FIG. 7 and the configuration diagram of FIG. In FIG. 8, the same parts as those in FIGS. In FIG. 8, obstructions 400 such as foliage plants exist in the optical transmission path between the spatial light transceivers 211 and 221B.

  Further, the distance LA between the node A and the spatial optical transceiver 211, the distance LB between the node B and the spatial optical transceiver 211, and the distance LC between the node C and the spatial optical transceiver 211 are expressed as LC> LA> LB. Is the farthest distance. The reception levels of the transmission signals TXA to TXC are set to TXA> TXC> TXB.

  7A to 7I show signal waveforms similar to those in FIGS. 6A to 6I, but FIGS. 7B, 7C, 7D, and 7G are used. , (H) have different waveforms.

  First, as shown in FIG. 7A, TXA to TXC are transmitted at the same timing at the IDLE transmission / reception timing. Next, in the spatial light transceiver 211 of the terminal-side electronic device 210, as shown in FIG. 7B, the TXA signal that arrives later than the shortest TXB is large. For this reason, the output voltage of the AGC amplifier 12 has a waveform different from that of FIG. 6C as shown in FIG. 7C. Even in this case, the AGC voltage has the highest signal strength as shown in FIG. Controlled by strong TXA, the output of the AGC amplifier 12 also matches the TXA level.

  FIG. 7 (d) also shows a state of comparison determination based on the threshold value 1.0 in the control unit 13 of the spatial light transceiver 211. In this case, the threshold value is between TXB and TXC, and TXB is not demodulated. Only TXA and TXC are demodulated. Even in this case, the gain of the AGC amplifier 12 is adjusted to TXA having the strongest signal level among the signals TXA to TXC as shown in FIG.

As a result, the data (DATA) signal sent from TXA can be received without any problems at the data transmission / reception timings shown after time t _{DATA in} FIGS. As described above, in this embodiment, the signal having the maximum signal strength can always be selected without necessarily depending on the arrival order of the signals. With this operation, even in downstream transmission, that is, DOWNLINK, the terminal-side electronic device 210 that receives the signal can always continuously receive a signal having the maximum signal strength.

As described above, according to the present embodiment, the following effects can be obtained.
(1) Expansion of the spatial light communication range In the spatial light communication, in order to extend the communication distance, it is necessary to narrow the light by inserting a lens into the light emitting element and the light receiving element. For this reason, when trying to earn a distance, the light reception angle becomes extremely narrow, and when applied to a terminal that is portable by humans, the communication angle is narrow, making it very difficult to adjust to the host side and extremely difficult to use It could have become.

By using this embodiment, the terminal side can communicate if it can connect to any node on the host side, so it is possible to increase the communication distance with a lens or the like and further widen the communication range (angle). .
(2) Improvement of tolerance against obstacles Obviously, in spatial light communication, communication is not possible when there are obstacles between spatial light transceivers. When this embodiment is used, communication is possible if there is a route that is not obstructed by the obstacle, and an improvement in the tolerance of the obstacle is expected. For example, as shown in FIG. 8, even when there is an obstruction 400 such as a foliage plant that causes attenuation of an optical signal in the middle, if there is a communicable route, communication is possible by using that route.
(3) Simple configuration In this embodiment, software processing by a CPU or the like is not required, and a plurality of communication points (for example, nodes A to C) are configured with a relatively simple control circuit as shown in FIG. It can be controlled. In particular, when mounted on a tablet PC or the like that requires portability, miniaturization is required, but as shown in FIG. 2A, special processing such as path switching is not particularly required on the tablet side. This means that the apparatus can be miniaturized and is effective.
(4) Stable operation of AGC amplifier by IDLE pattern In order to stably receive signals from a plurality of nodes at the terminal side, an IDLE pattern that is not related to direct communication data is added. Since transmission is simultaneously performed from the node, the AGC amplifier on the terminal side can be stably operated, and selection of the reception node on the terminal side can be made unnecessary.
(5) Stable reception by transmission selection The transmission node is selected according to the signal strength from the terminal side, but the IDLE signal is transmitted from all nodes regardless of the reception strength, and transmission from other nodes is stopped only at the time of data transmission / reception. And transmit from the node having the strongest reception strength.

  As a result, a communication route can be secured without simultaneously transmitting data from a plurality of nodes.

  Since the receiving terminal receives a transmission signal from only one node at the time of data reception, there is no need to simultaneously receive and process a plurality of signals, and the apparatus can be configured simply.

  Further, when there is no data from the host-side electronic device 220, the IDLE signal is transmitted at the same time, so the terminal side receives a plurality of IDLE signals at the same time. The purpose of the IDLE signal is for stable operation of the AGC circuit. It is not necessary to demodulate IDLE itself from the IDLE signal. For this reason, reception of a plurality of IDLE signals does not lead to complication of the terminal side device.

DESCRIPTION OF SYMBOLS 10 ... Photodiode 11, 14, 14a-14c ... Reception amplifier 12 ... AGC amplifier 13, 23 ... Control part 15, 15a-15c ... Transmission amplifier 16 ... LED driver 17 ... Light emitting diode 20, 20A-20C ... Connector 22 ... Reception Level detection unit 24, 34a to 34c ... buffer 30 ... signal control unit 31 ... IDLE generation unit 32 ... host interface 35 ... maximum reception level detection unit 36 ... switch control unit 210 ... terminal side electronic equipment 211, 221A-221C ... spatial light Transceiver 220 ... Host side electronic device 300 ... Signal selector 400 ... Interferer TXSW1-TXSW3 ... Transmission switch RXSW ... Reception switch

Claims (2)

A first communication apparatus having an optical transceiver configured to be movable and a first electronic device connected to the optical transceiver for transmitting and receiving data, a plurality of optical transceivers arranged in a distributed manner, and data Communication with a second electronic device that transmits / receives data and a second communication device that has signal selection means connected to the second electronic device to select the plurality of dispersed optical transceivers A spatial optical communication system,
The first electronic device has a function of transmitting a dummy signal when there is no transmission data,
The optical transmitter / receiver of the first communication device includes an optical transmitter that converts an electrical signal to be transmitted into an optical signal, an optical receiver that receives and converts the optical signal into an electrical signal, and an optical receiver. An AGC amplifier that holds the peak value of the converted electrical signal and performs automatic gain adjustment;
The plurality of transceivers of the second communication device includes: an optical transmission unit that converts an electrical signal to be transmitted into an optical signal and transmits the optical signal; an optical reception unit that receives and converts the optical signal into an electrical signal; and an optical reception unit An AGC amplifier that holds the peak value of the electrical signal converted in step (a) and performs automatic gain adjustment, and a reception level detector that detects the level of the electrical signal converted by the optical receiver,
The signal selection means includes
When there is no transmission data from the second electronic device to the plurality of optically arranged optical transceivers, a dummy signal is transmitted as a transmission signal, and a received signal from the optical transceiver to the second electronic device It has a function to delete dummy signals,
A transmission changeover switch for switching transmission of a transmission electrical signal path or a dummy signal from the second electronic device to any one of the plurality of optically arranged optical transceivers, and a second from each of the optical transceivers. A reception changeover switch for switching a reception electric signal path to the electronic device;
A maximum reception level detection unit for detecting an optical transmitter / receiver having a maximum reception level by obtaining a maximum value of an electric signal level detected by each reception level detection unit of the plurality of optically arranged optical transceivers distributed;
At the time of linking from the first communication device to the second communication device, the reception changeover switch is switched to the reception signal path on the optical transceiver side of the maximum reception level detected by the maximum reception level detector, Switch the transmission selector switch to the dummy signal transmission side,
At the time of linking from the second communication device to the first communication device, the reception changeover switch is switched to the reception signal path on the optical transceiver side of the maximum reception level detected by the maximum reception level detection unit, The transmission changeover switch is switched to the transmission side of the dummy signal when there is no transmission data from the second electronic device, and the maximum detected by the maximum reception level detection unit during the period when there is transmission data from the second electronic device. A switch control unit that performs control to switch to a transmission signal path on the optical transceiver side of the reception level;
A spatial optical communication system comprising: A first communication apparatus having an optical transceiver configured to be movable and a first electronic device connected to the optical transceiver for transmitting and receiving data, a plurality of optical transceivers arranged in a distributed manner, and data Communication with a second electronic device that transmits / receives data and a second communication device that has signal selection means connected to the second electronic device to select the plurality of dispersed optical transceivers A data transmission / reception method for a spatial light communication system, comprising:
Each of the optical transceivers of the first communication device and the second communication device includes an AGC amplifier that performs automatic gain adjustment by holding a peak value of an electric signal obtained by opto-electric conversion of the received optical signal,
Each optical transceiver of the second communication device includes a reception level detection unit that detects a level of an electrical signal obtained by photoelectrically converting the received optical signal,
The signal selection means includes a transmission changeover switch for switching transmission of a transmission electrical signal path or a dummy signal from the second electronic device to any of the plurality of optically arranged optical transceivers, and each of the optical transceivers. A reception changeover switch that switches a reception electrical signal path from any one to the second electronic device,
The first electronic device transmitting a dummy signal when there is no transmission data;
The signal selection means sending a dummy signal as a transmission signal when there is no transmission data from the second electronic device to the plurality of optically arranged optical transceivers;
The signal selecting means deleting a dummy signal in the received signal from each optical transceiver to the second electronic device;
The maximum reception level detection unit provided in the signal selection means obtains the maximum value of the electric signal level detected by each reception level detection unit of the plurality of optically arranged optical transceivers, and outputs the light of the maximum reception level. A maximum reception level detection step for detecting a transceiver;
When the switch control unit provided in the signal selection unit links from the first communication device to the second communication device, the switch of the maximum reception level detected by the maximum reception level detection unit is set to the reception changeover switch. Switching to the reception signal path on the optical transceiver side, switching the transmission switch to the transmission side of the dummy signal;
When the switch control unit is linked from the second communication device to the first communication device, the reception change-over switch is set to the reception signal on the optical transceiver side of the maximum reception level detected by the maximum reception level detection unit. Switching to a path, switching the transmission switch to a dummy signal transmission side during a period when there is no transmission data from the second electronic device, and the maximum reception level detecting unit during a period when there is transmission data from the second electronic device. Switching to the transmission signal path on the optical transceiver side of the maximum reception level detected in
A data transmission / reception method for a spatial optical communication system.

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