Underwater wireless communication device and method

Abstract

To make it possible to perform stabler communication under water by combining radio communication using sound and radio communication using light.SOLUTION: Underwater radio communication apparatuses 10 are provided at mobile bodies 2, 3 that are movable on water or under water, the underwater radio communication apparatuses performing radio communication under water using sound and light. The underwater radio communication apparatuses comprise: a sound radio communication unit 11 for performing radio communication using sound; a light radio communication unit 12 for performing radio communication using light; and a communication control unit 13 for controlling the sound radio communication unit and the light radio communication unit. The communication control unit controls the sound radio communication unit and the light radio communication unit according to predetermined communication management information TS that on the basis of a communication delay time, stipulates use timing of the sound radio communication unit and use timing of the light radio communication unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to underwater wireless communication devices and methods. [Background technology]

[0002] In recent years, there has been active development of technology for operating multiple AUVs (Autonomous Underwater Vehicles) with the aim of improving the efficiency of marine resource surveys, and underwater wireless communication technology between a mother ship and an AUV has attracted attention. Methods that use acoustic and optical technologies have been proposed as underwater wireless communication technologies.

[0003] Wireless communication using acoustic technology has little propagation loss and is therefore suitable for long-distance communication. However, wireless communication using acoustic technology is limited to low-speed data communication of a few kbps, making it unsuitable for transmitting large volumes of data collected for resource surveys from an AUV to a mother ship.

[0004] On the other hand, wireless communication using optical technology allows high-speed data communication of about 10 Mbps, but is not suitable for long-distance communication because light waves are attenuated in water.

[0005] Therefore, in addition to wireless communication using acoustic technology, Patent Document 1 proposes wireless communication using radio waves. In Patent Document 1, a plurality of different communication methods are switched according to depth information. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-61159 A Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 1 discloses a technique for combining acoustic communication and optical communication, but in the case of acoustic communication, the timing of transmission and reception of acoustic waves must be considered in order to prevent collisions of sound waves between underwater devices. Furthermore, since the speed of sound is slow, it takes time to establish acoustic communication underwater. On the other hand, in the case of optical communication, although the communication speed is fast, it is difficult to perform stable optical wireless communication underwater because light waves are significantly attenuated underwater.

[0008] The present invention has been made in consideration of the above problems, and aims to provide an underwater wireless communication device and method that combines acoustic wireless communication and optical wireless communication to enable more stable communication underwater. [Means for solving the problem]

[0009] In order to solve the above problems, an underwater wireless communication device according to one aspect of the present invention is an underwater wireless communication device that is mounted on a moving body that can move on or underwater, and that communicates wirelessly underwater using sound and light, and includes an acoustic wireless communication unit that communicates wirelessly using sound, an optical wireless communication unit that communicates wirelessly using light, and a communication control unit that controls the acoustic wireless communication unit and the optical wireless communication unit, and the communication control unit controls the acoustic wireless communication unit and the optical wireless communication unit in accordance with specified communication management information that specifies the timing of use of the acoustic wireless communication unit and the timing of use of the optical wireless communication unit based on the communication delay time. Effect of the Invention

[0010] According to the present invention, the acoustic wireless communication unit and the optical wireless communication unit can be controlled according to specified communication management information that specifies the timing of use of the acoustic wireless communication unit and the timing of use of the optical wireless communication unit based on the communication delay time. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an overall schematic diagram of an underwater wireless communication system that performs underwater wireless communication by switching between acoustic wireless communication and optical wireless communication between multiple different moving objects. [Diagram 2]FIG. 1 is a block diagram of an underwater wireless communication device. [Diagram 3] FIG. 2 is a block diagram of an acoustic communication control unit. [Figure 4] 4 is a diagram showing an example of the configuration of an audio packet. [Diagram 5] FIG. 4 is a block diagram of a transmission / reception time determination unit. [Figure 6] 4 is a flowchart of underwater wireless communication processing. [Figure 7] 4 is a time chart showing an example of underwater wireless communication. [Figure 8] 11 is a flowchart of a transmission method determination process performed at system startup. [Figure 9] 13 is a time chart illustrating an example of communication using large-volume data transmission in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The underwater wireless communication device according to this embodiment switches between acoustic wireless communication and optical wireless communication according to predetermined communication management information generated based on communication delay time. The transmission and reception time slot table TS described below is an example of "predetermined communication management information". The transmission and reception time determination unit 13 is an example of a "communication control unit".

[0013] The present disclosure includes the following configurations: In one disclosure, in an underwater wireless communication device 10 including an acoustic wireless communication unit 11, an optical wireless communication unit 12, and a transmission / reception time determination unit 13, the transmission / reception time determination unit 13 generates a transmission / reception time slot table TS of acoustic waves and light waves that takes into account the delay time of acoustic waves or light between the underwater wireless communication device 10S, the acoustic wireless communication unit 11 or the optical wireless communication unit 12 transmits the generated transmission / reception time slot table TS to the other underwater wireless communication device 10S, and the acoustic wireless communication unit 11 and the optical wireless communication unit 12 transmit and receive acoustic waves or light waves in accordance with the transmission / reception time slot table TS.

[0014] In another disclosure, the transmission / reception time slot table TS sets the timing of transmission and reception of sound waves and light waves so that the transmission and reception of sound waves and the transmission and reception of light do not overlap with other underwater wireless communication devices 10S.

[0015] In yet another disclosure, a positioning processing unit 1114, which is an example of an "environmental measurement unit", measures either the speed of sound, water depth, or attitude, and transmits these as positioning results to the transmission / reception time determination unit 13, and the transmission / reception time determination unit 13 generates a transmission / reception time slot table TS based on the received positioning results.

[0016] In another disclosure, the device further includes a transmission method determination unit 132, which determines whether to transmit the data to be transmitted by the acoustic wireless communication unit 11 or the optical wireless communication unit 12 according to the priority (or importance) of the data to be transmitted and the communication status, and based on this determination, the acoustic wireless communication unit 11 or the optical wireless communication unit 12 transmits or receives the data to be transmitted. The priority of data can be rephrased as the importance or urgency of the data.

[0017] In yet another disclosure, a communication status memory unit 133 is provided, which stores the communication status of the acoustic wireless communication unit 11 and the optical wireless communication unit 12 together with the positioning results, and the transmission method determination unit 132 determines whether to select the acoustic wireless communication unit 11 or the optical wireless communication unit 12 based on the latest positioning result, the data priority, and the information stored in the communication status memory unit 133.

[0018] According to this embodiment, stable underwater wireless communication can be performed by combining two types of communication methods, acoustic communication and optical communication. For example, the relative positions of moving bodies moving underwater or on the water change from moment to moment, and the water depth and water temperature also change, but communication can be performed in accordance with such changes. Hereinafter, acoustic communication may be referred to as, for example, acoustic wireless communication or sound communication. Optical communication may be referred to as, for example, optical wireless communication or optical communication. EXAMPLES

[0019] The first embodiment will be described with reference to FIGS.

[0020] [Overall configuration of underwater wireless communication system]

[0021] 1 shows the overall configuration of an underwater wireless communication system 1. The underwater wireless communication system 1 includes an underwater wireless communication device 10M mounted on a first moving body 2, and an underwater wireless communication device 10S mounted on a second moving body 2.

[0022] The first moving body 2 and the second moving body 3 are examples of "moving bodies capable of moving on or underwater." The first moving body 2 is, for example, a manned or unmanned ship. The first moving body 2 may be an ASV (unmanned small boat) or a buoy. The second moving body 3 is, for example, an unmanned or manned submarine. Hereinafter, the moving bodies 2 and 3 may be referred to as "underwater equipment." In this case, "underwater equipment" does not mean equipment that is always present underwater, but equipment with at least a part of its main body located underwater.

[0023] In this embodiment, the underwater wireless communication device 10M mounted on the mother ship 2 as the first moving body will be described as the master device, and the underwater wireless communication device 10S mounted on the AUV 3 as the second moving body will be described as the slave device. The relationship between the master device and the slave device may be reversed. That is, the underwater wireless communication device may be the master device, and the underwater wireless communication device above the water may be the slave device.

[0024] In the following, the explanation will be mainly focused on the underwater radio device on the mother ship side. When the underwater radio devices 10M, 10S are not particularly distinguished from one another, they will be referred to as the underwater wireless communication device 10. A detailed configuration of the underwater wireless communication device 10 will be described later. First, briefly explaining, the underwater wireless communication device 10 includes, for example, an acoustic wireless communication unit 11, an optical wireless communication unit 12, and a transmission / reception time determination unit 13. The transmission / reception time determination unit 13 includes a transmission / reception time slot table generation unit 131 and a transmission method determination unit 132.

[0025] Before starting communication with the other mobile body 3, the transmission method determination unit 132 transmits and receives test data via both the acoustic wireless communication unit 11 and the optical wireless communication unit 12, and determines whether to use acoustic waves or optical waves for communication.

[0026] The transmission and reception time slot table generating unit 131 generates a transmission and reception time slot table TS that takes into account the communication delay time, and transmits and receives data to and from the other mobile body 3 in accordance with the generated transmission and reception time slot table TS. In detail, in the transmission and reception time slot table TS, the transmission and reception timing is determined taking into account the communication delay time so that the sound waves transmitted from the acoustic wireless communication unit 11 of the first mobile body 2 and the sound waves transmitted from the acoustic wireless communication unit 11 of the second mobile body 3 do not interfere with each other midway.

[0027] The communication delay time can include the time required for a sound wave transmitted from one acoustic wireless communication unit 11 to arrive at the other acoustic wireless communication unit 11, and the time required for a reply (sound wave) to be transmitted from the other acoustic wireless communication unit 11.

[0028] Similarly, for the optical wireless communication units 12, a transmission and reception time slot table TS can be generated taking into account communication delay times so that transmissions from one optical wireless communication unit 12 do not overlap with transmissions from the other optical wireless communication unit 12.

[0029] [Configuration of underwater wireless communication device]

[0030] FIG. 2 is a block diagram showing an example of an underwater wireless communication device 10. As described above, the underwater wireless communication device 10 of this embodiment has multiple (two types of) wireless communication units with different communication methods, the acoustic wireless communication unit 11 and the optical wireless communication unit 12. The acoustic wireless communication unit 11 is a communication unit that transmits and receives sound waves. The optical wireless communication unit 12 is a communication unit that transmits and receives light waves. The acoustic wireless communication unit 11 and the optical wireless communication unit 12 realize wireless communication according to a transmission and reception time slot table TS generated by a transmission and reception time determination unit 13. Below, a configuration example of the acoustic wireless communication unit 11 will be described first, and then a configuration example of the optical wireless communication unit 12 will be described.

[0031] [Functional configuration of acoustic wireless communication unit 11]

[0032] A description will be given of the functional configuration of the acoustic wireless communication unit 11. The acoustic wireless communication unit 11 includes, for example, a wave transmitting unit 112, a wave receiving unit 113, and an acoustic communication control unit 111. The acoustic wireless communication unit 11 is connected to a sensor unit 15 and can receive various measurement data from the sensor unit 15.

[0033] 3 is a block diagram showing a functional configuration of the acoustic communication control unit 111. The acoustic communication control unit 111 includes, for example, a transmission data generating unit 1111, a modulating unit 1112, a demodulating unit 1113, and a positioning processing unit 1114.

[0034] The transmission data generating unit 1111 generates transmission data (digital signal) D14 including the transmission time information, the transmission / reception time slot table TS determined by the transmission / reception time determining unit 13, and the transmission method. An example of the transmission data D14 will be described later with reference to Fig. 4. In acoustic wireless communication, the amount of data that can be transmitted is small, so the data is encoded. In order to understand the communication status by sound waves, a mechanism for detecting and correcting errors that occur in the data is incorporated into the transmission data.

[0035] The modulation unit 1112 modulates the digital signal generated by the transmission data generation unit 1111 to generate an acoustic packet. In this way, the modulation unit 1112 generates a transmission signal (analog signal) for transmitting the transmission data D14 as an acoustic wave.

[0036] The modulation unit 1112 can use any modulation method. For example, the modulation unit 1112 may use digital modulation such as PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation). The modulation unit 1112 modulates the signal into a transmission signal suitable for driving the transmission unit 112 to generate a sound wave that can be efficiently propagated underwater.

[0037] 4 is a schematic diagram showing an example of the configuration of an audio packet D10. In addition to transmission data D14, the audio packet D10 includes, for example, a synchronization signal D11, a training signal D12, control information D13, and other information D15.

[0038] The synchronization signal D11 is a signal for identifying the underwater devices (moving bodies) 2, 3 and for locating the relative positions of the underwater devices. The training signal D12 is a signal for estimating the propagation path characteristics of the sound waves. The control information D13 includes transmission time information indicating the time when the sound waves were generated, a transmission / reception time slot table TS for controlling the transmission / reception timing of each underwater device, and a transmission method determined by the transmission method determination unit 132.

[0039] Returning to Fig. 2, the wave transmitting unit 112 amplifies the power of the wave transmitting signal based on the transmission time in the transmission / reception time slot table TS, and transmits (sends) sound waves in all directions. A piezoelectric wave transmitter having a piezoelectric ceramic vibrator as a wave transmitting element can be used for the wave transmitting unit 112. A piezoelectric ceramic vibrator has the property of generating distortion or stress when an electric field is applied.

[0040] The wave receiving unit 113 is configured as an array type wave receiving unit. That is, the array type wave receiving unit has a plurality of wave receiving units 113 arranged in one array. Each wave receiving unit 113 receives a reply to the sound waves transmitted in all directions from the wave transmitting unit 112 based on the reception time information in the transmission and reception time slot table TS.

[0041] Each wave receiving unit 113 amplifies the received wave receiving signal (analog signal), removes noise, and then performs A / D conversion (analog / digital conversion). Each wave receiving unit 113 can be, for example, a piezoelectric wave receiver equipped with a piezoelectric ceramic vibrator as a wave receiving element.

[0042] 3 demodulates the multiple received signals received by each receiver 113 into signals that can be processed. During demodulation, the demodulator 1113 performs error detection and error correction processing, and measures the bit error rate (BER) for the signal-noise ratio (SNR) of the received signal. The demodulator 1113 transmits the measurement result to the positioning processor 1114 and the transmission / reception time determination unit 13 as the communication status.

[0043] Furthermore, the demodulator 1113 decodes the control information D13 (transmission time information, transmission / reception time slot table TS, transmission method, etc.) and transmission data D14 in the acoustic packet D10. The demodulator 1113 regards the time at which the synchronization signal D11 in the acoustic packet D10 is detected as reception time information. The demodulator 1113 transmits the transmission time information and the reception time information of the synchronization signal D11 extracted from the control information D13 to the positioning processor 1114.

[0044] The positioning processing unit 1114 obtains the relative distance between the underwater devices 2 and 3 from the transmission time information and reception time information, which are the demodulation results for each received signal output from the demodulation unit 1113, and the propagation speed of sound waves underwater, which is the measurement result of the sensor unit 15. The positioning processing unit 1114 can also calculate the relative direction between the underwater devices 2 and 3 from the phase difference of the reception conditions of each received signal. The positioning processing unit 1114 can also correct the calculated relative direction with the water depth information and attitude information, which are the measurement results of the sensor unit 15. The positioning processing unit 1114 then transmits the relative positions of the underwater devices 2 and 3 to the transmission / reception time determination unit 13 as the positioning result.

[0045] As shown in Fig. 2, the sensor unit 15 includes multiple types of sensors 151, 152. The sensor unit 15 detects the surrounding environment of the underwater device and outputs a signal. The sensor unit 15 includes, for example, a sensor 151 that detects the speed of sound and pressure in water, and an attitude sensor 152 that detects the attitude of the underwater device. The detection result by the sensor unit 15 is transmitted to the acoustic communication control unit 111 and used by the positioning processing unit 1114 to correct the relative positions between the underwater devices. The sensor unit 15 is provided near the wave transmitting unit 112 and the wave receiving unit 113.

[0046] [Functional configuration of the optical wireless communication unit 12]

[0047] The following describes the functional configuration of the optical wireless communication unit 12 shown in Fig. 2. The optical wireless communication unit 12 includes an optical communication control unit 112, an irradiating unit 122, and a light receiving unit 123, for example.

[0048] The optical communication control unit 112 modulates the transmission data and transmits it as an optical signal to other underwater devices. That is, the optical communication control unit 112 generates transmission data including the transmission time information, the transmission / reception time slot table TS determined by the transmission / reception time determination unit 13, and the transmission method, modulates the generated transmission data so that it is carried on the carrier laser light, and causes the irradiation unit 122 to transmit the modulated light emission signal.

[0049] The optical communication control unit 112 demodulates and decodes the received optical signal received by the optical receiver 123 into a signal that can be processed, in accordance with the reception time information in the transmission and reception time slot table TS determined by the transmission and reception time determination unit 13. At this time, the optical wireless communication unit 112 performs error detection processing and error correction processing, measures the bit error rate (BER) relative to the SNR of the received optical signal, and transmits the measurement result to the transmission and reception time determination unit 13 as the communication status.

[0050] The irradiation unit 122 irradiates (transmits) laser light toward a predetermined wide-angle range based on the transmission time information written in the transmission / reception time slot table TS. Examples of sources of laser light include semiconductor lasers, gas lasers, and LEDs. Furthermore, the irradiation unit 122 may include a rotation mechanism for adjusting the irradiation angle, or a movable optical lens. The irradiation angle can be adjusted based on the amount of shaking detected by the attitude sensor 152 and the positioning result between the underwater devices.

[0051] The light receiving unit 123 receives laser light signals transmitted from other underwater devices based on the reception time information recorded in the transmission / reception time slot table TS. A photodiode or the like can be used as a laser light detector. Furthermore, the light receiving unit 123 may have a rotation mechanism or a movable optical lens that adjusts the light receiving angle based on the amount of shaking detected by the attitude sensor of the sensor unit 15 and the positioning result between the underwater devices.

[0052] [Functional configuration of transmission / reception time determination unit 13]

[0053] The functional configuration of the transmission / reception time determination unit 13 will be described with reference to Fig. 5. Fig. 5 is a block diagram showing an example of the functional configuration of the transmission / reception time determination unit 13. The transmission / reception time determination unit 13 is connected to a data input unit 14. The transmission / reception time determination unit 13 includes a transmission / reception time slot table generation unit 131, a transmission method determination unit 132, and a communication status storage unit 133.

[0054] The data input unit 14 inputs time information from the atomic clock and scheduled transmission data read from a memory (not shown) to the transmission / reception time determination unit 13. The atomic clock is a clock that keeps accurate time based on a highly accurate frequency standard, and serves as the basis for a transmission / reception time slot table TS that determines the timing for transmitting and receiving sound waves or light waves. The scheduled transmission data may be manually input from an input device (not shown). The input device may be a keyboard, a pointing device such as a mouse, or a touch panel.

[0055] The transmission data is a data packet (data signal) to be communicated with other underwater devices. The data packet includes, for example, transmission information such as priority and data size, and communication data.

[0056] The transmission / reception time slot table generation unit 131 calculates the communication delay time between other underwater devices based on the mutual positions between the underwater devices calculated by the positioning processing unit 1114 and the speed of sound detected by the sensor unit 15.

[0057] The transmission and reception time slot table generation unit 131 generates a transmission and reception time slot table TS based on the calculated communication delay time and turnaround time (the time from receiving a sound wave to transmitting the sound wave) so that the transmission and reception of sound waves does not overlap and so that the transmission and reception of light does not overlap.

[0058] In the transmission / reception time slot table TS, when the acoustic wireless communication unit 11 is transmitting sound waves, i.e., when it is in sound wave transmission mode, the optical wireless communication unit 12 is set to be in light wave reception mode. In the sound wave transmission mode, reception of sound waves is paused. In the light wave reception mode, transmission of light waves is paused. At this time, in the other underwater devices 3, the acoustic wireless communication unit 11 is in sound wave reception mode (transmission is paused) and the optical wireless communication unit 12 is in light wave transmission mode (reception is paused).

[0059] The generated transmission and reception time slot table TS is transmitted (notified) from the acoustic wireless communication unit 11 or the optical wireless communication unit 12 to the other underwater device 3. As a result, the transmission and reception time slot table TS is shared between the underwater wireless communication device 10M of the underwater device 2 and the underwater wireless communication device 10S of the other underwater device 3. Therefore, collisions of sound waves and light waves between the underwater devices 2 and 3 can be suppressed, and full-duplex communication using light waves and sound waves is realized between the underwater devices 2 and 3. In other words, data can be exchanged almost simultaneously between the underwater device 2 and the underwater device 3 by switching between transmitting and receiving sound waves and light waves.

[0060] The transmission method determination unit 132 determines a transmission method for the data packet based on the transmission information (priority and data size) included in the data packet of the data to be transmitted, the positioning result, and the communication situation.

[0061] The transmission method is determined including at least one of the communication method (acoustic communication, optical communication), frequency (wavelength), frequency bandwidth, modulation method, number of retransmissions, coding rate of error correction code, and transmission pulse width (transmission time length).

[0062] For example, when the priority of the information to be transmitted is high, a robust transmission method that can reliably transmit the information is determined. In the robust transmission method, for example, the communication method is acoustic communication, the frequency is 20 kHz, the frequency bandwidth is 2 kHz, the modulation method is BPSK, the number of retransmissions is 5, the error correction coding rate is 1 / 2, and the transmission pulse width is 100 ms.

[0063] Using the information stored in the communication status memory unit 133 (past positioning results and the relationship between SNR and BER for acoustic waves and light waves), a publicly known machine learning technique may be used to determine the optimal transmission method for the current positioning results and communication status.

[0064] The communication status storage unit 133 stores communication status according to the positioning result. For example, the stored communication status includes a measurement value of a bit error rate (BER) relative to the SNR of a signal received by the underwater device. Note that a volatile or non-volatile memory is used for the communication status storage unit 133. Examples of such memory include DRAM, SRAM, and flash memory.

[0065] [Communication using underwater wireless communication equipment]

[0066] The following describes the communication operation between the underwater wireless communication device 10M mounted on the mother ship 2 and the underwater wireless communication device 10S mounted on the AUV 3. In the following description, the underwater wireless communication device 10M on the mother ship side is referred to as the master device 10M, and the underwater wireless communication device 10S on the AUV side is referred to as the slave device 10S.

[0067] The mother ship 2 and AUV 3 are assumed to act autonomously in cooperation, and are controlled in cooperation so that the distance between the mother ship 2 and AUV 3 and the relative positions of the two are always the same. The distance between the mother ship 2 and AUV 3 and the relative positions of the two may be controlled by a position correction unit (not shown). The position correction unit controls the distance and the relative positions of the mother ship 2 and AUV 3 based on the positioning results of the positioning processing unit 1114 so that they are always the same.

[0068] Fig. 6 is a flow chart showing an example of the operation of the underwater wireless communication device 10M, and Fig. 7 is a time chart showing an example of communication between the underwater wireless communication device 10M and the underwater wireless communication device 10S. In Fig. 7, the time chart on the mother ship side is shown on the upper side, and the time chart on the AUV side is shown on the lower side. In each time chart, the upper side indicates transmission, and the lower side indicates reception. Each time chart shows the time when a data packet is transmitted and received based on the transmission and reception time and transmission method determined by the transmission and reception time determination unit 13.

[0069] The underwater wireless communication device 10M determines the transmission method (S11). Details of the transmission method determination process will be described in Fig. 8. In brief, the underwater wireless communication device 10M transmits and receives test pattern sound wave signals and light wave signals to the partner underwater wireless communication device 10S, thereby acquiring the communication status of each wireless communication unit 11, 12 and the relative positions between the underwater devices 2, 3, and determines the transmission method based on the transmission information (priority, data size) of the data to be transmitted.

[0070] The processing procedure of step S11 will be described with reference to Fig. 8. The master device 10M on the mother ship transmits and receives acoustic signals of a predetermined test pattern at predetermined times to and from the slave device 10S on the AUV to obtain the communication status and positioning results (communication distance), and stores the acoustic communication status according to the positioning results in the communication status storage unit 133 (S111).

[0071] Similarly, the master device 10M transmits and receives optical signals of a predetermined test pattern to and from the slave device 10S at a predetermined time to obtain the communication status and the positioning result (communication distance), and stores the optical communication status according to the positioning result in the communication status memory unit 133 (S112).

[0072] Master device 10M acquires transmission information (priority, data size) of the data scheduled to be transmitted (S113).

[0073] The master device 10M determines a transmission method based on the communication conditions, positioning results, and transmission information acquired in steps S111 to S113 (S114). The master device 10M transmits the transmission method determined in step S113 to the slave device 10S using the acoustic wireless communication unit 11 or the optical wireless communication unit 12, and the master device 10M and the slave device 10S share the transmission method (S115).

[0074] Returning to Fig. 6, when the master device 10M receives a response signal from the slave device 10S, it determines that communication has been established with the slave device 10S (S12: YES). The response signal is a signal indicating that the slave device 10S has normally received the transmission method transmitted from the master device 10M. In contrast, if the master device 10M cannot receive a response signal from the slave device 10S even after a certain period of time has elapsed since the master device 10M transmitted the transmission method to the slave device 10S, the master device 10M determines that communication has not been established (S12: NO) and returns to step S11.

[0075] The master device 10M generates a transmission and reception time slot table TS by the transmission and reception time slot table generation unit 131 (S13). That is, the master device 10M calculates the sound wave propagation time (communication delay time) between the underwater devices 2, 3 based on the communication distance calculated by the positioning processing unit 1114 and the sound speed detected by the sensor unit 15. Then, the master device 10M generates a transmission and reception time slot table TS based on this communication delay time and the turnaround time (the time from receiving a sound wave or light wave to transmitting it) so that the transmission and reception of sound waves and the transmission and reception of light waves do not overlap each other.

[0076] The master device 10M transmits the generated transmission and reception time slot table TS to the slave device 10S on the AUV side using the acoustic wireless communication unit 11 or the optical wireless communication unit 12, and shares the transmission and reception time slot table TS between each of the underwater devices 2, 3 (S14).

[0077] Master device 10M performs data communication with slave device 10S based on the transmission / reception time slot table TS generated in step S13 and the transmission method determined in step S11 (S15). This enables full-duplex communication as shown in the timing chart of Fig. 7. Similarly, slave device 10S also performs data communication with master device 10M based on the transmission / reception time slot table TS and the transmission method.

[0078] The master device 10M calculates the communication distance between itself and the slave device 10S from the sound waves received by the positioning processing unit 1114, and monitors whether the calculated communication distance has changed by a predetermined value or more (S16). For example, if the communication distance has changed by a predetermined value of 10 m or more (S16: YES), the master device 10M returns to step S13 and updates the transmission / reception time slot table TS. If the communication distance between the master device 10M and the slave device 10S has not changed by the predetermined value or more (S16: NO), the process returns to step S15.

[0079] The determination in step S16 may be based not only on the communication distance but also on changes in the communication conditions, including environmental noise. That is, the master device 10M can monitor changes in the communication conditions as well as changes in the communication distance between the master device 10M and the slave device 10S. This allows the master device 10M to determine the optimal transmission method according to the fluctuations in the communication environment, thereby achieving more stable wireless communication.

[0080] Let us explain the target in Figure 7. The white squares in the figure indicate that communication is carried out by sound waves. The shaded squares in the figure indicate that communication is carried out by light.

[0081] According to this embodiment configured as described above, more stable communication can be performed underwater by combining wireless communication using sound and wireless communication using light.

[0082] In this embodiment, the transmission and reception time slot table TS is shared by the master device 10M and the slave device 10S, and acoustic wireless communication or optical wireless communication is performed according to the transmission and reception time slot table TS, so that data can be transmitted and received efficiently.

[0083] In this embodiment, a transmission / reception time slot table TS is generated and shared between the master device 10M and the slave device 10S so that transmission and reception of optical wireless communications do not overlap, and transmission and reception of acoustic wireless communications do not overlap, thereby making it possible to prevent collisions of sound waves and to realize full-duplex communication.

[0084] In this embodiment, the transmission and reception time slot table TS is updated by measuring the speed of sound or water depth in water where wireless communication is performed, and the attitude changes of the underwater devices 2 and 3, so that stable communication can be performed by following the changes in the underwater environment. EXAMPLES

[0085] A second embodiment will be described with reference to Fig. 9. In this embodiment, differences from the first embodiment will be mainly described. In this embodiment, for example, a communication operation in a case where a submerged AUV 3 transmits a large amount of data collected by a resource survey to a mother ship 2 will be described.

[0086] At this time, the priority of the transmission information included in the data packet of the data to be transmitted is set to the high-speed communication mode. The transmission method and transmission / reception time slot table TS is set so that the transmission pulse width (transmission time length) of the optical wireless communication unit 12 of the slave device 10S on the AUV side is maximized. A time chart showing an example of communication at this time is shown in Figure 9.

[0087] Even in the high-speed communication mode using the optical wireless communication unit 12, if the communication conditions of the optical wireless communication deteriorate by a predetermined value or more due to, for example, an increase in the communication distance between underwater devices or an increase in underwater turbidity, the communication is switched to the acoustic wireless communication. At this time, the information stored in the communication condition storage unit 133 is referenced, and the transmission method (frequency, frequency bandwidth, modulation method, number of retransmissions, error correction coding rate, transmission pulse width) and the transmission and reception time slot table TS are updated.

[0088] The present embodiment thus configured also has the same operational effects as those of the first embodiment. Furthermore, in this embodiment, since a high-speed communication mode by the optical wireless communication unit 12 can be used, a large amount of data collected by the AUV 3 can be transmitted to the mother ship 2 in a short time.

[0089] The present invention is not limited to the above-described embodiment. A person skilled in the art can make various additions and modifications within the scope of the present invention. The above-described embodiment is not limited to the configuration example shown in the attached drawings. The configuration and processing method of the embodiment can be appropriately changed within the scope of achieving the object of the present invention.

[0090] In addition, the components of the present invention may be selected arbitrarily, and the invention having the selected components is also included in the present invention. Furthermore, the components described in the claims may be combined in combinations other than those explicitly stated in the claims. [Explanation of symbols]

[0091] 1: Underwater wireless communication system, 2: Mother ship, 3: AUV, 10: Underwater wireless communication device, 11: Acoustic wireless communication unit, 12: Optical wireless communication unit, 13: Transmission / reception time determination unit, 14: Data input unit, 15: Sensor unit

Claims

1. An underwater wireless communication device that is provided on a moving body that can move on or underwater and that wirelessly communicates underwater using sound and light, an acoustic wireless communication unit for wirelessly communicating using acoustics; an optical wireless communication unit for wirelessly communicating using light; a communication control unit that controls the acoustic wireless communication unit and the optical wireless communication unit, The communication control unit The acoustic wireless communication unit and the optical wireless communication unit are controlled in accordance with predetermined communication management information that specifies a usage timing of the acoustic wireless communication unit and a usage timing of the optical wireless communication unit based on a communication delay time. Underwater wireless communication equipment.

2. the acoustic wireless communication unit is configured to wirelessly communicate using acoustic signals with another acoustic wireless communication unit provided in another moving object, the optical wireless communication unit is configured to wirelessly communicate with another optical wireless communication unit provided in the other moving object using acoustics, The communication control unit shares the predetermined communication management information with another communication control unit that controls the other acoustic wireless communication unit and the other optical wireless communication unit.

2. The underwater wireless communication device according to claim 1.

3. The communication control unit, according to the predetermined communication management information, When the acoustic wireless communication unit is in a transmission mode, the optical wireless communication unit is in a reception mode, and when the acoustic wireless communication unit is in a reception mode, the optical wireless communication unit is in a transmission mode.

3. The underwater wireless communication device according to claim 2.

4. It also has an environmental measurement section, the environment measurement unit supplies to the communication control unit a measurement result obtained by measuring at least one of a sound speed or a water depth in water where wireless communication is performed, and an attitude of the moving body; The communication control unit generates the predetermined communication management information based on the measurement result.

4. The underwater wireless communication device according to claim 3.

5. The communication control unit generates the predetermined communication management information based on the priority set in the transmission scheduled data and the measurement result.

5. The underwater wireless communication device according to claim 4.

6. Further, a communication status storage unit is provided, the communication status storage unit stores a status of acoustic wireless communication and a status of optical wireless communication between the other moving body and the moving body as a communication status history; The communication control unit generates the predetermined communication management information based on the priority, the measurement result, and the communication status history.

6. An underwater wireless communication device according to claim 5.

7. An underwater wireless communication method for wirelessly communicating underwater using sound and light, comprising: an acoustic wireless communication unit that wirelessly communicates with another acoustic wireless communication unit using sound; an optical wireless communication unit that wirelessly communicates with another optical wireless communication unit (12) using light; The acoustic wireless communication unit and the optical wireless communication unit are controlled in accordance with predetermined communication management information that specifies the use timing of the acoustic wireless communication unit and the use timing of the optical wireless communication unit based on a communication delay time. Underwater wireless communication method.

Images