Communication device, control method, and program

Abstract

This communication device comprises: a first communication unit that receives a measurement signal for measuring communication quality; a second communication unit the frequency band of which is changeable; a measurement unit that measures the quality of communication with a device being communicated to, on the basis of the measurement signal received by the first communication unit; a determination unit that determines the frequency band used by the second communication unit according to the communication quality; and a band setting unit that sets the frequency band determined by the determination unit as a frequency band used by the second communication unit.

Description

Communication device, control method, and program

[0001] The present disclosure relates to a communication device, a control method, and a program.

[0002] As a technology for performing communication in water, for example, HD-PLC is known. Also, a technology for performing wireless communication in water is disclosed in Patent Document 1.

[0003] Japanese Patent Application Laid-Open No. 2018-61159

[0004] Generally, there is a trade-off relationship between communication distance and communication speed. However, particularly in wireless communication in water (hereinafter referred to as "underwater communication"), since radio waves rapidly attenuate when passing through water, the communication speed in water is more likely to decrease compared to the communication speed in air.

[0005] Under such circumstances, when the communication environment such as the distance state between devices performing underwater communication changes, it is necessary to set an appropriate frequency band. However, when the communication environment changes significantly, the communication is interrupted, and it has been difficult to set an appropriate frequency band.

[0006] Non-limiting embodiments of the present disclosure contribute to providing a communication device, a control method, and a program capable of setting an appropriate frequency band.

[0007] A communication device according to an embodiment of the present disclosure includes a first communication unit that receives a measurement signal for measuring communication quality, a second communication unit whose frequency band can be changed, a measurement unit that measures the communication quality with a communication destination device based on the measurement signal received by the first communication unit, a determination unit that determines a frequency band used by the second communication unit according to the communication quality, and a band setting unit that sets the frequency band determined by the determination unit as the frequency band used by the second communication unit.

[0008] A control method according to one embodiment of the present disclosure is a control method for a communication device comprising a first communication unit that receives a measurement signal for measuring communication quality and a second communication unit capable of changing the frequency band, wherein the first communication unit measures the communication quality with the communication destination device based on the measurement signal received by the first communication unit, determines the frequency band to be used by the second communication unit according to the communication quality, and sets the determined frequency band as the frequency band to be used by the second communication unit.

[0009] A program according to one embodiment of the present disclosure is a program that causes a computer of a communication device, which includes a first communication unit that receives a measurement signal for measuring communication quality and a second communication unit that can change the frequency band, to perform the following processes: measure the communication quality with a communication destination device based on the measurement signal received by the first communication unit, determine the frequency band to be used by the second communication unit according to the communication quality, and set the determined frequency band as the frequency band to be used by the second communication unit.

[0010] These comprehensive or specific embodiments may be implemented as systems, devices, methods, integrated circuits, computer programs, or recording media, or as any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

[0011] Non-limiting embodiments of this disclosure enable the setting of appropriate frequency bands.

[0012] Further advantages and effects of one embodiment of this disclosure will be made apparent from the specification and drawings. Such advantages and / or effects are provided by several embodiments and features described in the specification and drawings, but not all of them are necessarily provided in order to obtain one or more identical features.

[0013] A diagram showing an example configuration of a communication system including a communication device. A diagram showing an example of bandwidth and signal strength. A diagram showing an example of configurable bandwidth. A diagram showing the transfer speed and communication distance for each mode. A diagram showing an example configuration of a communication device according to the first embodiment. A sequence diagram showing an example of a control example (1) of the first embodiment. A diagram showing an example of a mode determination table. A sequence diagram showing an example of a control example (2) of the first embodiment. A sequence diagram showing an example of a control example (3) of the first embodiment. A diagram showing an example configuration of a communication device according to the second embodiment. A sequence diagram showing an example of a control example (1) of the second embodiment. A sequence diagram showing an example of a control example (2) of the second embodiment. A sequence diagram showing an example of a mode determination table (for distance).

[0014] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same function are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0015] Figure 1 is a diagram showing an example configuration of a communication system 10 including a communication device 100 according to an embodiment of the present invention. The example configuration shown in Figure 1 shows a configuration in which two communication devices 100 communicate underwater (in Figure 1, as an example, underwater).

[0016] The communication device 100 includes an antenna 110 for communicating with another communication device 100 (the communication destination device). The communication device 100 is also housed inside a housing 40 or inside an AUV (Autonomous Underwater Vehicle) 70. The housing 40 is, for example, a waterproof tank. Inside the housing 40, in addition to the communication device 100, there is an optical conversion unit 50. The optical conversion unit 50 and the optical conversion unit 30, which will be described later, perform OE conversion and EO conversion.

[0017] The communication device 100 inside the enclosure 40 is wired to the PC (Personal Computer) 20 and is capable of bidirectional communication. The communication device 100 outputs an electrical signal to the optical conversion unit 50. The optical conversion unit 50 converts the electrical signal output from the communication device 100 into an optical signal. The optical signal output from the optical conversion unit 50 is output to the optical conversion unit 30 via an optical fiber. The optical conversion unit 30 converts the input optical signal into an electrical signal and outputs it to the PC 20. The optical conversion unit 30 converts the electrical signal output from the PC 20 into an optical signal. The optical signal output from the optical conversion unit 30 is output to the optical conversion unit 50 via an optical fiber. The optical conversion unit 50 converts the input optical signal into an electrical signal and outputs it to the communication device 100. The communication device 100 receives the input electrical signal and transmits it to other communication devices 100 or uses it for its own control, etc.

[0018] The communication device 100 inside the AUV70 is connected to the robot control unit 60. The robot control unit 60 consists of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and controls the communication device 100 inside the AUV70, as well as the speed and direction of movement of the AUV70.

[0019] Next, we will explain the frequency bands (hereinafter sometimes simply referred to as "bandwidth") that can be set as the frequency band used by the communication device 100. The communication device 100 can change the band used for underwater communication. Figure 2 is a diagram showing an example of bandwidth and signal strength. In the graph shown in Figure 2, the horizontal axis represents frequency and the vertical axis represents signal strength. The graph on the right shows the band from 2 MHz to 28 MHz used for short-range high-speed communication. On the other hand, the graph on the left shows the band from 125 kHz to 1.75 MHz used for long-distance communication. It is also shown that the peak signal strength for long-distance communication is stronger compared to that for short-range high-speed communication.

[0020] Furthermore, the communication device 100 according to this embodiment can set not only the two types of bandwidths mentioned above, but also many other bandwidths. Figure 3 shows an example of bandwidths that can be set for use by the communication device 100 for underwater communication.

[0021] The graph shown in Figure 3 shows frequency on the horizontal axis and the types of configurable bandwidths (communication modes) on the vertical axis. The communication device 100 can set seven types of bandwidths, shown from Mode A to Mode G. As shown in Figure 3, the bandwidth of a certain communication mode is half the bandwidth of the communication mode above it and twice the bandwidth of the communication mode below it. For example, Mode B has a bandwidth with an upper limit of 14 MHz, which is half the upper limit of 28 MHz in the 2-28 MHz bandwidth of Mode A, and a lower limit of 1 MHz, which is half the lower limit of 2 MHz. Also, Mode B has a bandwidth with an upper limit of 14 MHz, which is twice the upper limit of 7 MHz in the 0.5-7 MHz bandwidth of Mode C, and a lower limit of 1 MHz, which is twice the lower limit of 0.5 MHz.

[0022] Next, we will explain the transfer speed and communication range for each communication mode. Figure 4 shows the transfer speed and communication range for each communication mode as measured underwater. In the graph shown in Figure 4, the horizontal axis represents the communication range (m), and the vertical axis represents the transfer speed (Mbps). The vertical axis is expressed on a logarithmic scale. As shown in Figure 4, communication modes closer to Mode A have faster transfer speeds but shorter communication ranges, while communication modes closer to Mode F have slower transfer speeds but longer communication ranges.

[0023] Based on the above, two embodiments will be described. The difference between the two embodiments lies in the configuration of the communication device 100.

[0024] <First Embodiment> Figure 5 is a diagram showing an example configuration of a communication device 100 according to the first embodiment. In Figure 5, the communication device 100 includes a main communication unit 120 and a sub-communication unit 130. The sub-communication unit 130 receives a measurement signal for measuring communication quality, measures the communication quality, and outputs the measured communication quality to the main communication unit 120. The main communication unit 120 determines a frequency band according to the input communication quality, sets the determined frequency band, and uses the set frequency band to communicate underwater with another communication device 100 that is the communication destination.

[0025] Furthermore, the main communication unit 120 and the sub-communication unit 130 are each composed of a CPU, ROM, RAM, etc. Communication between the main communication unit 120 and the sub-communication unit 130 is performed, for example, using serial communication.

[0026] Next, the details of the sub-communication unit 130 will be described. The sub-communication unit 130 includes a first communication unit 131 and a measurement unit 132. The first communication unit 131 is connected to the antenna 110 and transmits and receives measurement signals for measuring communication quality. The first communication unit 131 outputs the received measurement signal to the measurement unit 132. Based on the measurement signal, the measurement unit 132 measures the communication quality with other communication devices 100 that are the communication destination and outputs it to the main communication unit 120. In this embodiment, the received level of the measurement signal (RSSI (Received Signal Strength Indicator)) and CINR (Carrier-to-Interference-plus-Noise Ratio) are used as examples of communication quality.

[0027] Next, the main communication unit 120 will be described. The main communication unit 120 includes a second communication unit 121, a bandwidth setting unit 122, and a determination unit 140. The communication quality output by the sub-communication unit 130 is input to the determination unit 140. The determination unit 140 determines the frequency band to be used by the second communication unit 121 according to the communication quality and outputs the determined frequency band to the bandwidth setting unit 122. The bandwidth setting unit 122 sets the frequency band determined by the determination unit 140 as the frequency band to be used by the second communication unit 121. The second communication unit 121 is connected to the antenna 110 and uses the set frequency band to communicate underwater with other communication devices 100. The second communication unit 121 also transmits signals received from the PC 20 to other communication devices 100 via the optical conversion unit 50. The second communication unit 121 also outputs signals received from other communication devices 100 to the PC 20 via the optical conversion unit 50.

[0028] In this way, the communication device 100 can set an appropriate frequency band. Furthermore, by using the same antenna for the first communication unit 131 and the second communication unit 121, the device can be made more compact and cost-effective compared to a system where the first communication unit 131 and the second communication unit 121 use different antennas.

[0029] The bandwidth used by the first communication unit 131 is either one, the narrowest bandwidth among the frequency bands used by the second communication unit 121, or a bandwidth narrower than the frequency band used by the second communication unit 121. In this embodiment, the first communication unit 131 communicates underwater with another communication device 100, for example, in mode G.

[0030] By using only one bandwidth for the first communication unit 131, control becomes easier compared to the case where there are multiple bandwidths. Furthermore, by setting the bandwidth used by the first communication unit 131 to the narrowest bandwidth among the frequency bands used by the second communication unit 121, or a bandwidth lower than the frequency band used by the second communication unit 121, the first communication unit 131 can most reliably communicate underwater with the other communication device 100 within the range of bandwidth available to the communication device 100. This means that if the first communication unit 131 cannot communicate underwater with the other communication device 100, then the second communication unit 121 will not be able to communicate underwater with the other communication device 100 regardless of which communication mode it uses.

[0031] Next, the bandwidth used by the second communication unit 121 will be described. The second communication unit 121 communicates underwater with other communication devices 100 from mode A to mode G, or from mode A to mode F. Therefore, the number of frequency bands available to the first communication unit 131 is less than the number of frequency bands available to the second communication unit 121. In addition, some frequency bands (for example, mode G) are available for use by both the first communication unit 131 and the second communication unit 121. This allows for the common use of some bandwidths, making control easier. Also, some frequency bands (for example, from mode A to mode F) are unavailable to the first communication unit 131 but available to the second communication unit 121. By reducing the bandwidth used by the first communication unit 131 in this way, control becomes easier compared to when it is not reduced.

[0032] Next, three control examples in the first embodiment will be described. Each control example shows a control example in underwater communication between the communication device 100 and another communication device 100 that is the communication destination, and the configuration of the other communication device 100 that is the communication destination is also as shown in Figure 5. For convenience, the communication device 100 will be described as the parent and the other communication device 100 that is the communication destination as the child.

[0033] Figure 6 is a sequence diagram showing a control example (part 1) of the first embodiment. In Figure 6, the parent sub-communication unit 130 transmits a measurement signal to another communication device 100 in mode G (step S101). The child sub-communication unit 130 measures the received level (RSSI (Received Signal Strength Indicator)) of the received measurement signal (step S102).

[0034] The child's sub-communication unit 130 transmits a measurement signal to the communication device 100 in the same communication mode (mode G) as the parent's communication mode (step S103). The child's sub-communication unit 130 also outputs a reception level to the child's main communication unit 120 (step S104).

[0035] The parent's sub-communication unit 130 receives the measurement signal transmitted by the child's sub-communication unit 130 and measures the reception level (RSSI) of the received measurement signal (step S105). The parent's sub-communication unit 130 outputs the reception level to the parent's main communication unit 120 (step S106). The parent's main communication unit 120 determines the communication mode according to the reception level (step S107). This determination method will be described later. The parent's main communication unit 120 sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S108) and starts communication in the set band (step S109).

[0036] Meanwhile, the child's main communication unit 120 determines the communication mode according to the reception level (step S110). The determination method is the same as that of the parent's main communication unit 120. The child's main communication unit 120 sets the frequency band used by the child's second communication unit 121 to the band indicated by the determined communication mode (step S111), and starts underwater communication in the set band (step S112).

[0037] Next, the method for determining the communication mode will be explained. Figure 7 shows an example of a mode determination table referenced by the determination unit 140. The mode determination table is a table that associates RSSI-based values ​​(hereinafter referred to as "RSSI conversion values") with communication modes, and is stored in the storage device (e.g., ROM) of the main communication unit 120 or the sub-communication unit 130 (e.g., ROM). The RSSI conversion values ​​on the horizontal axis are values ​​normalized from 0 to 100 of the RSSI values. The closer the RSSI conversion value is to 0, the weaker the radio wave strength, and the closer it is to 100, the stronger the radio wave strength. In this embodiment, the RSSI conversion values ​​are divided into 10 groups (0 to 10, ..., 90 to 100). In the mode determination table, for each group, the communication modes predetermined as appropriate communication modes are indicated by circles.

[0038] The determination unit 140 derives an RSSI conversion value from the acquired RSSI and determines the communication mode corresponding to the group to which the derived RSSI conversion value belongs. For example, if the RSSI conversion value is 85, the determination unit 140 determines that 85 belongs to the group of 80 to 90, and therefore determines mode A, which is marked with a circle for the group of 80 to 90, as the communication mode for the second communication unit 121. In this way, by using the mode determination table, the communication device 100 can set an appropriate frequency band. The method of determining the communication mode described in Figure 7 may be referred to as "determination method A" in the following description.

[0039] Another method for determining the communication mode is to use an AI model trained on RSSI, the communication mode determined by that RSSI, and the communication quality at that time to determine the communication mode best suited to RSSI.

[0040] Next, an example of control in which the communication mode is shared between the parent and child will be described. Figure 8 is a sequence diagram showing the control example (part 2) of the first embodiment. In Figure 8, the parent's sub-communication unit 130 transmits a measurement signal to the other communication device 100 that is the communication destination in mode G (step S201). The child's sub-communication unit 130 measures the reception level (RSSI) of the received measurement signal (step S202).

[0041] The sub-communication unit 130 of the child transmits a measurement signal to the communication device 100 in the same communication mode (mode G) as the communication mode of the parent (step S203). Also, the sub-communication unit 130 of the child outputs the reception level to the main communication unit 120 of the child (step S204). The main communication unit 120 of the child determines the communication mode by determination method A according to the reception level (step S207).

[0042] The sub-communication unit 130 of the parent receives the measurement signal transmitted by the sub-communication unit 130 of the child, and measures the reception level (RSSI) of the received measurement signal (step S205). The sub-communication unit 130 of the parent outputs the reception level to the main communication unit 120 of the parent (step S206). The main communication unit 120 of the parent determines the communication mode by determination method A according to the reception level (step S208).

[0043] The main communication unit 120 of the parent notifies the other communication device 100 of the communication destination of the determined communication mode, for example, using a Beacon (step S209). Next, the main communication unit 120 of the parent sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S210), and starts underwater communication in the set band (step S211).

[0044] The main communication unit 120 of the child, to which the communication mode is notified, checks the consistency between the communication mode determined in step S207 above and the notified communication mode (step S212). Specifically, when the communication mode determined in step S207 above and the notified communication mode are different, the main communication unit 120 of the child determines the communication mode to the notified communication mode. The main communication unit 120 of the child sets the frequency band used by the second communication unit 121 of the child to the band indicated by the determined communication mode (step S213), and starts underwater communication in the set band (step S214).

[0045] By sharing the communication mode between the parent and the child in this way, it is possible to prevent interruption of underwater communication that may occur when different communication modes are set for the parent and the child.

[0046] Next, a control example when the communication quality deteriorates during underwater communication between the parent and the child will be described. FIG. 9 is a sequence diagram showing a control example (No. 3) of the first embodiment. In the sequence diagram shown in FIG. 9, after the communication mode is set in the control examples (No. 1 and No. 2) of the first embodiment and underwater communication is started, when the communication quality deteriorates, the main communication unit 120 of the parent and the main communication unit 120 of the child perform channel estimation and attempt to improve it. Examples of improvements attempted by the main communication unit 120 of the parent and the main communication unit 120 of the child include changing the number of bits carried on the carrier.

[0047] Note that the deterioration of the communication quality described above means, for example, that the retransmission rate of packets exceeds a threshold or the number of lost packets exceeds a threshold. These thresholds may be provided for each communication mode. This is because it is considered that the statistical quantities (e.g., average values) of the retransmission rate and the number of lost packets are different for each communication mode.

[0048] When the communication quality is not improved, the main communication unit 120 of the parent notifies the sub-communication unit 130 of the parent of a CINR measurement instruction (step S301). Similarly, the main communication unit 120 of the child notifies the sub-communication unit 130 of the child of a CINR measurement instruction (step S302).

[0049] The sub-communication unit 130 of the parent transmits a measurement signal to another communication device 100 at the communication destination (step S303). Also, the sub-communication unit 130 of the child receives the measurement signal, and the measurement unit 132 of the child performs a CINR measurement (step S304). Next, the sub-communication unit 130 of the child transmits the measurement signal to the communication device 100 (step S305). The sub-communication unit 130 of the parent receives the measurement signal, and the measurement unit 132 of the parent performs a CINR measurement (step S306).

[0050] In steps S303 to S306 described above, CINR measurement is performed by the measurement unit 132 for each communication mode. The CINR measurement results are output as CINR measurement information to the parent's main communication unit 120 in step S307, and to the child's main communication unit 120 in step S311. In this embodiment, the CINR information is information indicating the frequency at which noise is generated in at least the bandwidth used in each communication mode (31.25 kHz to 28 MHz: see Figure 3).

[0051] Upon receiving the CINR measurement information, the parent main communication unit 120 determines the communication mode according to the CINR measurement information (step S308). This determination method will be described later. The parent main communication unit 120 sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S309), and starts underwater communication in the set band (step S310).

[0052] Similar to the parent unit, the child unit's main communication unit 120, upon receiving CINR measurement information, determines a communication mode according to the CINR measurement information (step S312). The child unit's main communication unit 120 sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S313), and starts underwater communication in the set band (step S314).

[0053] The determination method in steps S308 and S312 described above will now be explained. The determination method according to the CINR measurement information is to determine a communication mode that does not include the frequency in which noise is generated in the CINR measurement information. This method may be referred to as "Determination Method B" in the following explanation.

[0054] For example, if the CINR measurement information indicates that noise is occurring between 15 MHz and 20 MHz, the system will be configured to one of modes B through G, excluding mode A. For example, if the quality deteriorates during underwater communication in mode A, and the CINR measurement information indicates that noise is occurring between 15 MHz and 20 MHz, then mode B will be configured. In this way, the communication device 100 can set an appropriate frequency band.

[0055] <Second Embodiment> Figure 10 shows an example of the configuration of the communication device 100 according to the second embodiment. The difference from the first embodiment is that the determination unit 140 is included in the sub-communication unit 130 instead of the main communication unit 120. In Figure 10, the communication device 100 includes the main communication unit 120 and the sub-communication unit 130. The sub-communication unit 130 receives a measurement signal for measuring communication quality, measures the communication quality, determines the frequency band according to the communication quality, and outputs the determined frequency band to the main communication unit 120. The main communication unit 120 sets the input frequency band and uses the set frequency band to communicate underwater with other communication devices 100 that are the communication destinations.

[0056] Furthermore, the main communication unit 120 and the sub-communication unit 130 are each composed of a CPU, ROM, RAM, etc. Communication between the main communication unit 120 and the sub-communication unit 130 is performed, for example, using serial communication.

[0057] Next, the details of the sub-communication unit 130 will be described. The sub-communication unit 130 includes a first communication unit 131, a measurement unit 132, and a determination unit 140. The first communication unit 131 is connected to the antenna 110 and transmits and receives measurement signals for measuring communication quality. The first communication unit 131 outputs the received measurement signal to the measurement unit 132. Based on the measurement signal, the measurement unit 132 measures the communication quality with other communication devices 100 and outputs it to the determination unit 140. In this embodiment, the received level (RSSI) and CINR of the measurement signal are used as examples of communication quality. The determination unit 140 determines the frequency band to be used by the second communication unit 121 according to the communication quality and outputs the determined frequency band to the main communication unit 120.

[0058] Next, the main communication unit 120 will be described. The main communication unit 120 includes a second communication unit 121 and a bandwidth setting unit 122. The frequency band output by the sub-communication unit 130 is input to the bandwidth setting unit 122. The bandwidth setting unit 122 sets the frequency band determined by the determination unit 140 as the frequency band to be used by the second communication unit 121. The second communication unit 121 is connected to the antenna 110 and uses the set frequency band to communicate underwater with other communication devices 100. The second communication unit 121 also transmits signals received from the PC 20 to other communication devices 100 via the optical conversion unit 50. The second communication unit 121 also outputs signals received from other communication devices 100 to the PC 20 via the optical conversion unit 50.

[0059] In this way, the communication device 100 can set an appropriate frequency band. Furthermore, by using the same antenna for the first communication unit 131 and the second communication unit 121, the device can be made more compact and cost-effective compared to a system where the first communication unit 131 and the second communication unit 121 use different antennas.

[0060] The bandwidth used by the first communication unit 131 is either one, the narrowest bandwidth among the frequency bands used by the second communication unit 121, or a bandwidth narrower than the frequency band used by the second communication unit 121. In this embodiment, the first communication unit 131 communicates underwater with another communication device 100, for example, in mode G.

[0061] By using only one bandwidth for the first communication unit 131, control becomes easier compared to the case where there are multiple bandwidths. Furthermore, by setting the bandwidth used by the first communication unit 131 to the narrowest bandwidth among the frequency bands used by the second communication unit 121, or a bandwidth lower than the frequency band used by the second communication unit 121, the first communication unit 131 can most reliably communicate underwater with the other communication device 100 within the range of bandwidth available to the communication device 100. This means that if the first communication unit 131 cannot communicate underwater with the other communication device 100, then the second communication unit 121 will not be able to communicate underwater with the other communication device 100 regardless of which communication mode it uses.

[0062] Next, the bandwidth used by the second communication unit 121 will be described. The second communication unit 121 communicates underwater with other communication devices 100 from mode A to mode G, or from mode A to mode F. Therefore, the number of frequency bands available to the first communication unit 131 is less than the number of frequency bands available to the second communication unit 121. In addition, some frequency bands (for example, mode G) are available for use by both the first communication unit 131 and the second communication unit 121. This allows for the common use of some bandwidths, making control easier. Also, some frequency bands (for example, from mode A to mode F) are unavailable to the first communication unit 131 but available to the second communication unit 121. By reducing the bandwidth used by the first communication unit 131 in this way, control becomes easier compared to when it is not reduced.

[0063] Next, three control examples in the second embodiment will be described. Each control example shows a control example in underwater communication between the communication device 100 and another communication device 100 that is the communication destination, and the configuration of the other communication device 100 that is the communication destination is also the configuration shown in Figure 10. For convenience, the communication device 100 will be described as the parent and the other communication device 100 that is the communication destination as the child.

[0064] Figure 11 is a sequence diagram showing a control example (part 1) of the second embodiment. In Figure 11, the parent sub-communication unit 130 transmits a measurement signal to another communication device 100, for example, in mode G (step S401). The child sub-communication unit 130 measures the reception level (RSSI) of the received measurement signal (step S402).

[0065] The child's sub-communication unit 130 transmits a measurement signal to the communication device 100 in the same communication mode as the parent's communication mode (for example, mode G) (step S403). The child's sub-communication unit 130 also determines the communication mode according to the reception level using determination method A (step S404). The child's sub-communication unit 130 outputs the determined communication mode to the child's main communication unit 120 (step S410).

[0066] The child's main communication unit 120 sets the frequency band used by the child's second communication unit 121 to the band indicated by the determined communication mode (step S411), and starts underwater communication in the set band (step S412).

[0067] The parent's sub-communication unit 130 receives the measurement signal transmitted by the child's sub-communication unit 130 and measures the reception level (RSSI) of the received measurement signal (step S405). This reception level is an example of status information indicating the communication state. The parent's sub-communication unit 130 determines the communication mode according to the reception level using determination method A (step S406). The parent's sub-communication unit 130 outputs the determined communication mode to the parent's main communication unit 120 (step S407).

[0068] The main communication unit 120 sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S408), and starts underwater communication in the set band (step S409). In this way, the communication device 100 can set an appropriate frequency band.

[0069] Next, an example of control in which the communication mode is shared between the parent and child will be described. Figure 12 is a sequence diagram showing an example of control in the second embodiment (part 2). In Figure 12, the parent's sub-communication unit 130 transmits a measurement signal to the other communication device 100 in mode G (step S501). The child's sub-communication unit 130 measures the reception level (RSSI) of the received measurement signal (step S502). The child's sub-communication unit 130 transmits the measurement signal to the communication device 100 in the same communication mode (mode G) as the parent's communication mode (step S503). The child's sub-communication unit 130 determines the communication mode according to the reception level using determination method A (step S505).

[0070] The parent's sub-communication unit 130 receives the measurement signal transmitted by the child's sub-communication unit 130 and measures the reception level (RSSI) of the received measurement signal (step S504). The parent's sub-communication unit 130 determines the communication mode according to the reception level using determination method A (step S506). The parent's sub-communication unit 130 outputs the determined communication mode to the parent's main communication unit 120 (step S507).

[0071] The parent's sub-communication unit 130 notifies the other communication device 100 of the determined communication mode (step S508). Next, the parent's main communication unit 120 sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S509), and starts underwater communication in the set band (step S510).

[0072] The child's sub-communication unit 130, upon receiving notification of the communication mode, confirms the consistency between the communication mode determined in step S505 and the notified communication mode (step S511). Specifically, if the communication mode determined in step S505 and the notified communication mode are different, the child's sub-communication unit 130 determines the communication mode to the notified communication mode. The child's sub-communication unit 130 outputs the determined communication mode to the child's main communication unit 120 (step S512). The child's main communication unit 120 sets the frequency band used by the child's second communication unit 121 to the band indicated by the determined communication mode (step S513), and starts underwater communication in the set band (step S514).

[0073] By sharing the communication mode between the parent and child in this way, it is possible to prevent the disruption of underwater communication that may occur if different communication modes are set for the parent and child.

[0074] In the above explanation, an example was described in which the parent's sub-communication unit 130 notifies the other communication device 100 of the determined communication mode in step S508, but the parent's main communication unit 120 may also make the notification. In a specific example, the parent's main communication unit 120 notifies the other communication device 100 of the determined communication mode using Beacon or the like (step S508). In this case, the child's main communication unit 120 is notified of the communication mode determined in step S505 by the child's sub-communication unit 130, and performs the consistency check equivalent to step S511 on behalf of the child's sub-communication unit 130. If the communication mode notified by the parent's main communication unit 120 and the communication mode notified by the child's sub-communication unit 130 are different, the child's main communication unit 120 may decide on the communication mode notified by the child's main communication unit 120. Also, the frequency band used for Beacon communication is, for example, the frequency band corresponding to the communication mode determined in step S506.

[0075] Next, we will describe an example of control when the communication quality deteriorates during underwater communication between the parent and child devices. Figure 13 is a sequence diagram showing the control example (3) of the second embodiment. In the sequence diagram shown in Figure 13, if the communication quality deteriorates after the communication mode has been set in the control examples (1 and 2) of the second embodiment and underwater communication has started, the parent's main communication unit 120 and the child's main communication unit 120 will perform channel estimation and attempt to improve the quality. An example of improvement that the parent's main communication unit 120 and the child's main communication unit 120 may attempt is to change the number of bits transmitted to the carrier.

[0076] The aforementioned deterioration in communication quality refers, for example, to situations where the packet retransmission rate exceeds a threshold or the number of lost packets exceeds a threshold. These thresholds may be set for each communication mode. This is because the statistical values ​​(e.g., average values) for the retransmission rate and the number of lost packets are likely to differ for each communication mode.

[0077] If the communication quality does not improve, the parent's main communication unit 120 notifies the parent's sub-communication unit 130 of a CINR measurement instruction (step S601). Similarly, the child's main communication unit 120 notifies the child's sub-communication unit 130 of a CINR measurement instruction (step S602).

[0078] The parent's sub-communication unit 130 transmits the measurement signal to the other communication device 100 (step S603). The child's sub-communication unit 130 receives the measurement signal, and the child's measurement unit 132 performs CINR measurement (step S604). Next, the child's sub-communication unit 130 transmits the measurement signal to the communication device 100 (step S605). The parent's sub-communication unit 130 receives the measurement signal, and the parent's measurement unit 132 performs CINR measurement (step S606).

[0079] In steps S603 to S606 described above, CINR measurements are repeatedly performed for each communication mode. The CINR measurement results are output as CINR measurement information to the determination unit 140 in both the parent and child devices. In this embodiment, the CINR information indicates the frequency at which noise is generated in at least the bandwidth corresponding to each communication mode (31.25 kHz to 28 MHz: see Figure 3).

[0080] The parent's sub-communication unit 130 determines the communication mode using determination method B according to the CINR measurement information (step S608). The parent's sub-communication unit 130 notifies the other communication device 100 that is the communication destination of the determined communication mode (step S609). The parent's sub-communication unit 130 notifies the parent's main communication unit 120 of the determined communication mode (step S610).

[0081] The main communication unit 120 sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S611), and starts underwater communication in the set band (step S612).

[0082] Similar to the parent unit, the child's sub-communication unit 130 determines the communication mode using determination method B according to the CINR measurement information (step S607). The child's sub-communication unit 130, which has been notified of the communication mode in step S609, checks the consistency between the communication mode determined in step S607 and the notified communication mode (step S613). Specifically, if the communication mode determined in step S607 and the notified communication mode are different, the child's sub-communication unit 130 determines the communication mode to the notified communication mode.

[0083] The child's sub-communication unit 130 notifies the parent's main communication unit 120 of the determined communication mode (step S614). The child's main communication unit 120 sets the frequency band used by the second communication unit 121 to the band indicated by the determined communication mode (step S615), and starts underwater communication in the set band (step S616). In this way, the communication device 100 can set an appropriate frequency band. In addition, it is possible to prevent interruption of underwater communication that may occur due to different communication modes being set between the parent and child.

[0084] In the above explanation, an example was described in which the parent's sub-communication unit 130 notifies the other communication device 100 of the determined communication mode in step S609, but the parent's main communication unit 120 may also make the notification. In a specific example, the parent's main communication unit 120 notifies the other communication device 100 of the determined communication mode using Beacon or the like (step S609). In this case, the child's main communication unit 120 is notified of the communication mode determined in step S607 by the child's sub-communication unit 130, and performs the consistency check equivalent to step S613 on behalf of the child's sub-communication unit 130. If the communication mode notified by the parent's main communication unit 120 and the communication mode notified by the child's sub-communication unit are different, the child's main communication unit 120 may decide on the communication mode notified by the child's main communication unit 120. Also, the frequency band used for Beacon communication is, for example, the frequency band corresponding to the communication mode determined in step S608.

[0085] <Method for Determining Communication Mode Using Distance> As an example of how to determine the communication mode using RSSI, method A was given, but other methods will be explained. It is generally known that the distance between antennas can be determined from RSSI. This is also true underwater. Therefore, the determination unit 140 first determines the distance from RSSI and determines the communication mode according to the distance.

[0086] Figure 14 shows an example of a mode determination table (for distance). The mode determination table (for distance) is a table that associates the distance between antennas with the communication mode, and is stored in the storage device (e.g., ROM) of the main communication unit 120 or the sub-communication unit 130 (e.g., ROM). The distance between antennas on the horizontal axis is divided into 10 groups (0 to 10, ..., 90 to 100). In the mode determination table (for distance), the communication mode predetermined as the appropriate communication mode for each group is indicated by a circle. Note that in water, especially in the sea, the distance may differ even with the same RSSI due to differences in water quality, etc. Therefore, for example, a table showing the RSSI and the corresponding distance may be prepared for each sea area, and the distance may be determined more accurately by referring to this table.

[0087] In the first and second embodiments described above, a distance-based determination method may be applied instead of determination method A.

[0088] <Regarding the measurement signal> In this embodiment, the measurement signal can be any signal that is capable of measuring communication quality. Specifically, in the embodiment described above, RSSI and CINR were given as examples of measuring communication quality, but RSSI can be measured based on any signal, including ordinary signals. On the other hand, CINR is measured based on a specific measurement signal. Thus, the measurement signal in this embodiment can be a dedicated signal for measurement or an ordinary signal.

[0089] <Summary of Embodiments> A communication device according to one embodiment of the present disclosure includes: a first communication unit that receives a measurement signal for measuring communication quality; a second communication unit capable of changing the frequency band; a measurement unit that measures the communication quality with a communication destination device based on the measurement signal received by the first communication unit; a determination unit that determines the frequency band to be used by the second communication unit according to the communication quality; and a band setting unit that sets the frequency band determined by the determination unit as the frequency band to be used by the second communication unit. This makes it possible to set an appropriate frequency band.

[0090] A control method according to one embodiment of the present disclosure is a control method for a communication device comprising a first communication unit that receives a measurement signal for measuring communication quality and a second communication unit capable of changing the frequency band, wherein the first communication unit measures the communication quality with the communication destination device based on the measurement signal received by the first communication unit, determines the frequency band to be used by the second communication unit according to the communication quality, and sets the determined frequency band as the frequency band to be used by the second communication unit. This makes it possible to set an appropriate frequency band.

[0091] A program according to one embodiment of the present disclosure is a program that causes a computer of a communication device, which includes a first communication unit that receives a measurement signal for measuring communication quality and a second communication unit that can change the frequency band, to perform the following processes: measure the communication quality with the communication destination device based on the measurement signal received by the first communication unit, determine the frequency band to be used by the second communication unit according to the communication quality, and set the determined frequency band as the frequency band to be used by the second communication unit. This makes it possible to set an appropriate frequency band.

[0092] This disclosure can be implemented using software, hardware, or software integrated with hardware.

[0093] Each functional block used in the description of the above embodiments may be implemented partially or entirely as an integrated circuit (LSI), and each process described in the above embodiments may be controlled partially or entirely by a single LSI or a combination of LSIs. An LSI may consist of individual chips, or it may consist of a single chip that includes some or all of the functional blocks. An LSI may have data inputs and outputs. Depending on the degree of integration, LSIs may be referred to as ICs, system LSIs, super LSIs, or ultra LSIs.

[0094] The integrated circuit implementation method is not limited to LSIs; it may also be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, a Field Programmable Gate Array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that allows for the reconfiguration of the connections and settings of circuit cells within the LSI, may also be used. This disclosure may be implemented as digital or analog processing.

[0095] Furthermore, if advancements in semiconductor technology or other derived technologies lead to the emergence of integrated circuit technologies that can replace LSIs, then naturally, it would be possible to use those technologies to integrate functional blocks. The application of biotechnology, for example, is a possibility.

[0096] Although various embodiments have been described above with reference to the drawings, it goes without saying that this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure. Furthermore, the components in the above embodiments may be combined in any way without departing from the spirit of the disclosure.

[0097] The specific examples of this disclosure have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples described above.

[0098] All disclosures in the specification, drawings, and abstract contained in the Japanese application No. 2024-209395, filed on December 2, 2024, are incorporated herein by reference.

[0099] One embodiment of the present disclosure is suitable for a communication device that communicates underwater.

[0100] 10 Communication system 100 Communication device 110 Antenna 121 Second communication unit 122 Bandwidth setting unit 131 First communication unit 132 Measurement unit 140 Determination unit

Claims

1. A communication device comprising: a first communication unit that receives a measurement signal for measuring communication quality; a second communication unit capable of changing the frequency band; a measurement unit that measures the communication quality with a communication destination device based on the measurement signal received by the first communication unit; a determination unit that determines the frequency band to be used by the second communication unit according to the communication quality; and a band setting unit that sets the frequency band determined by the determination unit as the frequency band to be used by the second communication unit.

2. The communication device according to claim 1, wherein the frequency band used by the second communication unit is notified to the communication destination device.

3. The communication device according to claim 1, wherein the number of frequency bands used by the first communication unit is one.

4. The communication device according to claim 1, wherein the frequency band used by the first communication unit is the narrowest band among the frequency bands used by the second communication unit, or a band narrower than the frequency band used by the second communication unit.

5. The communication device according to claim 1, wherein the number of frequency bands usable by the first communication unit is less than the number of frequency bands usable by the second communication unit.

6. The communication device according to claim 1, wherein a portion of the frequency band is available for use by the first communication unit and the second communication unit.

7. The communication device according to claim 1, wherein some frequency bands are unavailable to the first communication unit and available to the second communication unit.

8. The communication device according to claim 1, wherein the determination unit determines the frequency band to be used by the second communication unit according to the distance to the communication destination device determined from the communication quality.

9. The communication device according to claim 1, wherein the first communication unit and the second communication unit use the same antenna.

10. A control method for a communication device comprising a first communication unit that receives a measurement signal for measuring communication quality and a second communication unit capable of changing the frequency band, the control method comprising: measuring the communication quality with a communication destination device based on the measurement signal received by the first communication unit; determining the frequency band to be used by the second communication unit according to the communication quality; and setting the determined frequency band as the frequency band to be used by the second communication unit.

11. A program that causes a computer in a communication device, comprising a first communication unit that receives a measurement signal for measuring communication quality and a second communication unit capable of changing the frequency band, to perform the following processes: measure the communication quality with a communication destination device based on the measurement signal received by the first communication unit; determine the frequency band to be used by the second communication unit according to the communication quality; and set the determined frequency band as the frequency band to be used by the second communication unit.

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