Communication device, communication method, and communication system

Abstract

This communication device (10) comprises a light-emitting unit (11) that emits light and transmits a communication signal, and control units (13, 14) that control the light-emitting unit (11). When the light-emitting unit (11) is not transmitting the communication signal, the control units (13, 14) control the light-emitting unit (11) so as to be in a first standby state in which the light-emitting unit (11) emits light to such an extent that responsiveness is not impaired, or a second standby state in which the light-emitting unit (11) is turned off.

Description

Communication devices, communication methods, and communication systems Cross-reference of related applications

[0001] This application claims priority to Japanese Patent Application No. 2025-008047 (filed on January 20, 2025), the entire disclosure of said application is incorporated herein by reference.

[0002] This disclosure relates to communication devices, communication methods, and communication systems.

[0003] Generally, sound waves or visible light are used for communication underwater. In communication using visible light (optical communication), lasers or LEDs (Light Emitting Diodes) are used as light-emitting elements. For example, Patent Document 1 discloses a communication device using a blue semiconductor laser.

[0004] Japanese Patent Publication No. 2017-228889

[0005] (1) A communication device according to one embodiment of the present disclosure includes a light-emitting unit that emits light to transmit a communication signal, and a control unit that controls the light-emitting unit, wherein when the light-emitting unit is not transmitting a communication signal, the control unit controls the light-emitting unit to enter a first standby state in which the light-emitting unit emits light to an extent that does not impair responsiveness, or a second standby state in which the light-emitting unit is turned off.

[0006] (2) In one embodiment of the present disclosure, the present invention provides a light receiving unit for receiving light, and when the control unit obtains resource allocation information via the light receiving unit, the control unit puts the light emitting unit into the first standby state or the second standby state in the frame following the frame in which the resource allocation information was obtained, depending on whether or not the light emitting unit transmits.

[0007] (3) In one embodiment of the present disclosure, in (2), when the control unit obtains resource allocation information via the light receiving unit, in the frame following the frame in which the resource allocation information was obtained, the control unit transitions the light-emitting unit from the second standby state to the first standby state before the light-emitting unit transmits.

[0008] (4) In one embodiment of the present disclosure, in any of (1) to (3), a turbidity sensor is provided for detecting the turbidity of water, and the control unit selects a light emission color according to the detected turbidity of the water and puts the light emission unit that emits light of the unselected light emission color into the second standby state.

[0009] (5) In one embodiment of the present disclosure, in any of (1) to (4), a temperature sensor is provided to detect the temperature of the light-emitting unit, and when the control unit acquires resource allocation information, if the detected temperature of the light-emitting unit is below a threshold, the control unit does not put the light-emitting unit into the second standby state in the frame following the frame in which the resource allocation information was acquired.

[0010] (6) In one embodiment of the present disclosure, in any of (1) to (5), when the control unit transmits resource allocation information, it adjusts the allocation of the multiple terminal devices in the resource allocation information so that the transmission timings from multiple adjacent terminal devices are not adjacent.

[0011] (7) In one embodiment of the present disclosure, in any of (1) to (6), the control unit adjusts the signal level of the drive signal that controls the light-emitting unit using a DC bias.

[0012] (8) A communication method according to one embodiment of the present disclosure includes the step of a control unit that controls a light-emitting unit that emits light and transmits a communication signal, so that when the light-emitting unit is not transmitting a communication signal, the light-emitting unit enters a first standby state in which it emits light to an extent that does not impair responsiveness, or a second standby state in which the light-emitting unit is turned off.

[0013] (9) A communication system according to one embodiment of the present disclosure comprises a base station and a terminal device, the communication device provided in the base station and the terminal device each comprising: a light-emitting unit that emits light to transmit a communication signal; and a control unit that controls the light-emitting unit, the control unit controls the light-emitting unit to enter a first standby state in which the light-emitting unit emits light to an extent that does not impair responsiveness, or a second standby state in which the light-emitting unit is turned off, when the light-emitting unit is not transmitting a communication signal.

[0014] Figure 1 is a diagram showing an example configuration of a communication device according to one embodiment of the present disclosure. Figure 2 is a diagram showing an example configuration of a communication system according to one embodiment of the present disclosure. Figure 3 is a diagram illustrating the first standby state and the second standby state of the light-emitting unit. Figure 4 is a diagram showing an example of a frame format in optical communication. Figure 5 is a diagram showing an example of a state transition of the light-emitting unit. Figure 6 is a diagram showing another example of a state transition of the light-emitting unit. Figure 7 is a diagram showing an example of using the first standby state and the second standby state depending on the temperature of the light-emitting unit. Figure 8 is a diagram illustrating the adjustment of assignments for multiple adjacent terminal devices. Figure 9 is a diagram illustrating the adjustment of the signal level of the drive signal.

[0015] Hereinafter, a communication device 10 (see Figure 1), a communication method performed by the communication device 10, and a communication system according to one embodiment of the present disclosure will be described with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0016] Figure 1 shows an example configuration of the communication device 10 according to this embodiment. Figure 2 shows an example configuration of the communication system according to this embodiment. The communication system according to this embodiment performs optical communication, which is wireless communication using light, underwater. The communication system has a base station AP and terminal devices UT, and each of the base station AP and terminal devices UT is equipped with a communication device 10. In the example of Figure 2, the communication system has n terminal devices UT, and each of the terminal devices UT is subscripted as UT １ UT ２ UT ３ UT ｎ This is shown. Here, the communication system only needs to have one or more terminal devices UT, and n is not limited to a specific number.

[0017] Here, the terminal device UT may be installed on a mobile body. Also, the base station AP may be installed on an object installed in water to guide the mobile body. The mobile body can be, for example, an autonomous underwater vehicle (AUV) or another type of underwater vehicle. Also, the object can be, for example, a dock (resident) that stores the mobile body and performs power supply or data transfer, etc. In this example, using optical communication, the object side can guide the mobile body, perform position control of the mobile body from the object side, or cause the mobile body to perform a specific operation from the object side. The base station AP may be able to grasp the positional relationship of each terminal device UT (for example, one terminal device UT １ and the terminal device UT ２ are close to each other, while the terminal device UT ３ is the terminal device UT １ and the terminal device UT ２ exists at a position far from them). The base station AP can, for example, grasp the positional relationship of each terminal device UT based on the direction of light transmitted from each terminal device UT (see also the description of the light receiving unit 12 to be described later). In addition, the base station AP can also grasp the positional relationship of each terminal device UT by, for example, equipping the base station AP with a camera capable of imaging the surroundings.

[0018] The communication device 10 includes a light emitting unit 11 that emits light based on a drive signal, a light receiving unit 12 that receives light, and a control unit having a function of controlling the light emitting unit 11. In the present embodiment, the control unit has a signal generation unit 13 and a light emission drive unit 14. The control unit may further have another functional unit. The signal generation unit 13 controls the light emission drive unit 14 based on various information. The light emission drive unit 14 is controlled by the signal generation unit 13 and outputs a drive signal to the light emitting unit 11. In the following, the processing executed by the signal generation unit 13 or the light emission drive unit 14 can be rephrased as the processing executed by the control unit. Also, the communication device 10 may include a turbidity sensor 20 that detects the turbidity of water. Also, the communication device 10 may include a temperature sensor 30 that detects the temperature of the light emitting unit 11. The turbidity sensor 20 and the temperature sensor 30 can each use a known sensor.

[0019] The light-emitting unit 11 emits light to transmit a communication signal. In the following, the state in which the light-emitting unit 11 emits light and transmits a communication signal in order to communicate with the base station AP or terminal device UT will be simply referred to as "the light-emitting unit 11 is transmitting" or "the light-emitting unit 11 is performing a transmission." The state in which the light-emitting unit 11 is not transmitting the above communication signal will be referred to as "the light-emitting unit 11 is not transmitting" or "the light-emitting unit 11 is not performing a transmission." The light-emitting unit 11 may be composed of, for example, a laser or an LED. The light-emitting unit 11 may also be composed of multiple lasers or LEDs so that it can emit light in multiple directions. For example, the light-emitting unit 11 of the communication device 10 of the base station AP may be composed of multiple lasers or LEDs, and the light-emitting unit 11 of the communication device 10 of the terminal device UT may be composed of a single laser or LED.

[0020] The light receiving unit 12 receives light emitted as a communication signal. The light receiving unit 12 may be composed of, for example, a photodiode. The light receiving unit 12 may also be composed of multiple photodiodes so as to be able to receive light from multiple directions. For example, the light receiving unit 12 of the communication device 10 of a base station AP may be composed of multiple photodiodes. The light receiving unit 12 of the communication device 10 of a terminal device UT may be composed of a single photodiode. The light received by the light receiving unit 12 is converted into an electrical communication signal (received communication signal) by a functional unit of the control unit (which may be the light receiving unit 12 itself) and output to the signal generation unit 13. The received communication signal may be amplified before being output to the signal generation unit 13 if the light receiving unit 12 further has an amplifier. The signal generation unit 13 may convert the received communication signal from an analog signal to a digital signal using, for example, an AD converter, and generate a drive signal according to the content of the received communication signal.

[0021] The light-emitting drive unit 14 generates a drive signal according to the control of the signal generation unit 13 and outputs it to the light-emitting unit 11. The light-emitting drive unit 14 is a so-called driver and may be provided separately from the signal generation unit 13 as in this embodiment, or it may be included in the signal generation unit 13.

[0022] The signal generation unit 13 controls the generation of the drive signal and also controls the state of the light-emitting unit 11 via the drive signal. In this embodiment, the signal generation unit 13 causes the light-emitting drive unit 14 to generate the drive signal. The signal generation unit 13 may further include a data generation unit that converts the digital signal into an analog signal to generate the original data (original waveform) of the drive signal, and an adjustment unit that adjusts the signal level of the original data. The data generation unit may be composed of, for example, a DA converter.

[0023] Furthermore, at least a part of the control unit (for example, the signal generation unit 13) may be composed of one or more processors. The processor may be a general-purpose processor (for example, a CPU) that reads a program and executes a specific function, or a dedicated processor specialized for a specific process (for example, an ASIC). At least a part of the control unit may operate according to a program stored in memory. The program may be stored and provided on a recording medium.

[0024] Here, as shown in Figure 3, in the conventional device, when there is no transmission signal on the light-emitting side, a current corresponding to the amplitude center of the carrier wave (carrier average current If_c) flows through the light-emitting element. Therefore, in the conventional device, the power consumption of the light-emitting unit 11 is large during the no-signal section (the section without a transmission signal). In other words, even in the standby state where no communication signal is being transmitted, unnecessary power consumption and heat generation occur, and the deterioration of the light-emitting element progresses. In the communication device 10, communication method, and communication system according to this embodiment, in the no-signal section, the light-emitting unit 11 can be set to a first standby state in which it emits light to an extent that does not impair responsiveness, or to a second standby state in which it is completely turned off, thereby reducing power consumption in the standby state. The details of the first standby state and the second standby state will be described below.

[0025] In this embodiment, the drive signal generated by the light-emitting drive unit 14 in accordance with the control of the signal generation unit 13 includes a transmission signal, which is an analog signal corresponding to the communication signal; a first standby signal, which puts the light-emitting unit 11 into a first standby state; and a second standby signal, which puts the light-emitting unit 11 into a second standby state. The second standby signal is a signal level that turns off the light by reducing the current flowing through the light-emitting unit 11 to zero. The first standby signal is a signal level that causes the light-emitting unit 11 to emit light to an extent that does not impair responsiveness. Not impairing responsiveness means that even if communication is started immediately, there will be no delay or decrease in the amount of light emitted by the light-emitting unit 11. Therefore, the amount of light emitted to an extent that does not impair responsiveness is not limited to a specific amount of light if the responsiveness of the emitted light is good, but it may be defined as the amount of light that corresponds to the trough (bottom) in the change in the amount of light emitted during communication, or it may be defined as the lower limit of light emission of the components constituting the light-emitting unit 11.

[0026] Here, Figure 4 shows an example of a frame format in optical communication. In this embodiment, one frame includes eight subframes (the first to eighth subframes). DL indicates downlink (downlink communication from base station AP to terminal device UT). UL indicates uplink (uplink communication from terminal device UT to base station AP). The "DL Super Subframe (first subframe)" is a subframe that synchronizes communication and specifies the communication target (resource) and communication order. The "UL Super Subframe (fifth subframe)" is a subframe for terminal device UT that has not been allocated resources (in the example in Figure 2, terminal device UT) ｎ ) is a subframe for random access from the base station AP, requesting resource allocation from the base station AP (see Figure 6). In other "Data Subframes", data is transmitted. The data may be, for example, an optical signal for calculating the distance between the base station AP and the resource-allocated terminal device UT, but is not limited to any specific data. Here, frame ｘ－１ is frame ｘ This is the frame immediately preceding it. ｘ－１ The next frame ｘ The communication targets and communication order are frame ｘ－１This is predetermined in the first subframe. Therefore, each terminal device UT has already received information about the communication target and communication order at the start of each frame, and can set in which subframe to transmit or wait at the start of each frame.

[0027] Figure 5 shows an example of the state transitions of the light-emitting unit 11. Figure 6 shows another example of the state transitions of the light-emitting unit 11. In Figures 5, 6, 7, and 8, the vertical axis shows which state the light-emitting unit 11 is in, corresponding to the amount of power consumed. The horizontal axis shows time. The signal generation unit 13 causes the light-emitting drive unit 14 to generate a drive signal, either a first standby signal to put the light-emitting unit 11 into a first standby state or a second standby signal to put the light-emitting unit 11 into a second standby state, when the light-emitting unit 11 is not transmitting a communication signal. In other words, the control unit controls the light-emitting unit 11 so that, when the light-emitting unit 11 is not transmitting a communication signal, the light-emitting unit 11 enters either a first standby state where it emits light to an extent that does not impair responsiveness, or a second standby state where the light-emitting unit 11 is turned off.

[0028] Furthermore, when the signal generation unit 13 acquires resource allocation information via the light receiving unit 12, it may put the light-emitting unit 11 into a first standby state or a second standby state in the frame following the frame in which the resource allocation information was acquired, depending on whether or not the light-emitting unit 11 transmits. In the example in Figure 4, the resource allocation information is "DL Super Subframe (first subframe)". Specifically, the signal generation unit 13 puts the light-emitting unit 11 into a second standby state if the light-emitting unit 11 does not transmit, but it may transition the light-emitting unit 11 from the second standby state to the first standby state before the light-emitting unit 11 transmits. In the examples in Figures 5 and 6, the light-emitting unit 11 is in the first standby state (waiting for the next signal) for at least a portion of the subframe before the light-emitting unit 11 transmits (turns on). Also, when the light-emitting unit 11 is not transmitting, the light-emitting unit 11 is in the second standby state (off), except for the first standby state (waiting for the next signal). By controlling the signal generation unit 13 in this way, power consumption in the standby state can be reduced while improving responsiveness during transmission. For example, if transmission is started from a state where the light-emitting unit 11 is completely off, noise may be generated due to the steep rise of the drive signal, or a voltage drop may occur, which may cause unstable circuit operation. By transitioning the light-emitting unit 11 from the second standby state to the first standby state before the light-emitting unit 11 performs transmission, unstable circuit operation can be avoided.

[0029] The signal generation unit 13, when the communication device 10 is configured to include a turbidity sensor 20, may select a light emission color according to the detected turbidity of the water and put the light emission unit 11 that emits light of the unselected light emission color into a second standby state. In this case, power consumption in the standby state can be further reduced. Here, as the light emission color, it is generally preferable to select a color whose wavelength of light is included in the range of 430 nm to 550 nm (for example, blue), but depending on the degree of turbidity of the water, it may be preferable to use a color outside this wavelength range (for example, red). When the communication device 10 is configured to allow selection of, for example, a blue light emission unit 11 and a red light emission unit 11, the signal generation unit 13 puts the light emission unit 11 of the unselected light emission color (for example, the blue light emission unit 11 that is not used) into a second standby state.

[0030] Figure 7 shows an example of how to use the first and second standby states depending on the temperature of the light-emitting unit 11. The signal generation unit 13 does not need to use the second standby state depending on the temperature of the light-emitting unit 11 if the communication device 10 is configured to have a temperature sensor 30. In other words, when the signal generation unit 13 acquires resource allocation information via the light-receiving unit 12, if the detected temperature of the light-emitting unit 11 is below a threshold, it does not need to put the light-emitting unit 11 into the second standby state in the frame following the frame in which the resource allocation information was acquired. For example, if the temperature of the light-emitting unit 11 is below a threshold (50°C as an example), the circuit operation may not be stable. Before the light-emitting unit 11 transmits, it is possible to warm the light-emitting unit 11 by putting it into the first standby state instead of the second standby state and flowing a small current, thereby improving the responsiveness during transmission. In Figure 7, the first standby state for warming the light-emitting unit 11 is indicated as "First standby state (temperature rise)" to distinguish it from the first standby state (next signal standby).

[0031] Figure 8 is a diagram illustrating the adjustment of allocations for multiple adjacent terminal devices UT. When the signal generation unit 13 of the base station AP's communication device 10 transmits resource allocation information, it may adjust the allocation of multiple terminal devices in the resource allocation information so that the transmission timings from multiple adjacent terminal devices UT are not adjacent. In the example in Figure 8, terminal devices UT １ and terminal device UT ２ Because they are located close together, if the transmission timings are adjacent as shown in Figure 5 (the 6th and 7th subframes in Figure 5), the terminal device UT １ Light and terminal device UT ２ Light from the terminal device UT may interfere. Therefore, the signal generation unit 13 is configured to allow light from the terminal device UT to interfere. １ and terminal device UT ２ To ensure that the timing of transmissions from each device is not adjacent, the resource allocation information is set to include terminal device UT. ２ and terminal device UT ３ The timing of transmission is adjusted by swapping the elements (the 6th and 8th subframes in Figure 8).

[0032] FIG. 9 is a diagram for explaining the adjustment of the signal level of the drive signal. As described above, the signal generation unit 13 may be configured to include a data generation unit and an adjustment unit. In this case, the data generation unit generates original data in accordance with the dynamic range of the DA converter. Then, the adjustment unit applies a DC bias (DC bias) obtained by adding the current of the first standby state to the maximum amplitude of the current of the original data. Here, when there is no adjustment unit, the signal generation unit 13 needs to generate original data within a range obtained by removing the current of the first standby state from the dynamic range of the DA converter. Therefore, the signal generation unit 13 can widely use the dynamic range by adjusting the signal level of the drive signal using the DC bias.

[0033] The above communication device 10 possessed by each of the base station AP and the terminal device UT executes a communication method. The communication method includes a step in which the signal generation unit 13 generates, as a drive signal, a first standby signal for causing the light emitting unit 11 to enter the first standby state or a second standby signal for causing the light emitting unit 11 to enter the second standby state when the light emitting unit 11 is not transmitting.

[0034] As described above, the communication device 10, the communication method, and the communication system according to the present embodiment can reduce the power consumption in the standby state as compared with the conventional method by the above configuration. Further, by reducing the power consumption in the standby state, heat generation and deterioration of the light emitting element can be suppressed.

[0035] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or corrections based on the present disclosure. Therefore, it should be noted that these modifications or corrections are included in the scope of the present disclosure. For example, in the above embodiment, although the communication device 10 and the communication system are assumed to be used underwater, they are also applicable to communication other than underwater.

[0036] 10 Communication device 11 Light emitting unit 12 Light receiving unit 13 Signal generation unit 14 Light emission drive unit 20 Turbidity sensor 30 Temperature sensor

Claims

1. A communication device comprising: a light-emitting unit that emits light to transmit a communication signal; and a control unit that controls the light-emitting unit, wherein the control unit controls the light-emitting unit to enter a first standby state in which the light-emitting unit emits light to an extent that does not impair responsiveness, or a second standby state in which the light-emitting unit is turned off, when the light-emitting unit is not transmitting a communication signal.

2. The communication device according to claim 1, comprising a light-receiving unit for receiving light, wherein the control unit, when it obtains resource allocation information via the light-receiving unit, causes the light-emitting unit to enter the first standby state or the second standby state in the frame following the frame in which the resource allocation information was obtained, depending on whether or not the light-emitting unit transmits.

3. The communication device according to claim 2, wherein when the control unit acquires resource allocation information via the light receiving unit, in the frame following the frame in which the resource allocation information was acquired, the light-emitting unit transitions from the second standby state to the first standby state before the light-emitting unit transmits.

4. A communication device according to any one of claims 1 to 3, comprising a turbidity sensor for detecting the turbidity of water, wherein the control unit selects a light emission color according to the detected turbidity of water, and puts the light emission unit that emits light of the unselected light emission color into the second standby state.

5. A communication device according to any one of claims 1 to 4, comprising a temperature sensor for detecting the temperature of the light-emitting unit, wherein when the control unit acquires resource allocation information, if the detected temperature of the light-emitting unit is below a threshold, the control unit does not put the light-emitting unit into the second standby state in the frame following the frame in which the resource allocation information was acquired.

6. The communication device according to any one of claims 1 to 5, wherein the control unit adjusts the allocation of the multiple terminal devices in the resource allocation information so that the timing of transmissions from the multiple adjacent terminal devices are not adjacent when transmitting resource allocation information.

7. The communication device according to any one of claims 1 to 6, wherein the control unit adjusts the signal level of the drive signal that controls the light-emitting unit using a DC bias.

8. A communication method comprising the step of controlling a light-emitting unit that emits light to transmit a communication signal, such that when the light-emitting unit is not transmitting a communication signal, the unit enters a first standby state in which it emits light to an extent that does not impair responsiveness, or a second standby state in which the light-emitting unit is turned off.

9. A communication system comprising a base station and a terminal device, wherein each of the base station and the terminal device comprises a communication device having a light-emitting unit that emits light to transmit a communication signal, and a control unit that controls the light-emitting unit, wherein the control unit controls the light-emitting unit to enter a first standby state in which the light-emitting unit emits light to an extent that does not impair responsiveness, or a second standby state in which the light-emitting unit is turned off, when the light-emitting unit is not transmitting a communication signal.

Images