Communication range estimation device, communication range estimation method, communication range estimation program, and communication range estimation system

Abstract

The present invention efficiently predicts a communication range in an underwater environment. This communication range estimation device (10) is used for estimating a communication range by sound wave signals in an underwater environment. The communication range estimation device includes: a memory (12) for storing a table (T1) that represents a first relationship between a communication signal-to-noise ratio and a signal error rate; and an information processing unit (11). The information processing unit executes: derivation processing (S11) for deriving, on the basis of a communication environment condition in the underwater environment, a second relationship between the signal-to-noise ratio and a transmission-reception positional relationship between the transmission and reception sides; and estimation processing (S12) for estimating a communication range in the underwater environment on the basis of the first relationship represented in the table and the derived second relationship.

Description

Communication range estimation device, communication range estimation method, communication range estimation program, and communication range estimation system

[0001] The present invention relates to a communication range estimation device, a communication range estimation method, a communication range estimation program, and a communication range estimation system.

[0002] When communicating underwater, it is advantageous to be able to predict the communication range appropriately in order to maintain communication. Because the communication range underwater changes depending on the environmental conditions, there is no guarantee that good communication will continue.

[0003] Patent document 1 discloses a technology for estimating the bit error rate of acoustic communication between a surface station and an underwater mobile body through propagation simulation, and if the bit error rate is greater than a standard, estimating the positions of the surface station and the underwater mobile body where the bit error rate is below the standard.

[0004] Japanese Patent Application Publication No. 2019-197969

[0005] However, if one tries to predict the communication range (e.g., the appropriate direction and distance between the surface station and the underwater mobile body) using the technology of Patent Document 1, a complicated propagation simulation using convolution operations based on impulse responses is required.

[0006] One aspect of the present invention has been made in consideration of the above-mentioned problems, and one example of its objective is to provide a communication range estimation device, a communication range estimation method, a communication range estimation program, and a communication range estimation system that aim to efficiently predict communication ranges.

[0007] A communication range estimation device according to one aspect of the present invention is a communication range estimation device used to estimate a communication range using a sound wave signal in an underwater environment, and includes a memory that stores a table that represents a first relationship between a communication signal-to-noise ratio and a signal error rate, and an information processing unit. The information processing unit performs a derivation process that derives a second relationship between the transmitting and receiving positional relationship and the signal-to-noise ratio between a transmitting side and a receiving side based on communication environment conditions in the underwater environment, and an estimation process that estimates the communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship.

[0008] According to one aspect of the present invention, it is possible to provide a communication range estimation device, a communication range estimation method, a communication range estimation program, and a communication range estimation system that improve the efficiency of underwater communication range prediction.

[0009] FIG. 1 is a diagram illustrating a communication range estimation device according to a first exemplary embodiment of the present invention. FIG. 2 is a flow diagram illustrating a processing flow in a communication range estimation method according to a first exemplary embodiment of the present invention. FIG. 3 is a diagram illustrating a communication range estimation system according to a second exemplary embodiment of the present invention. FIG. 4 is a flow diagram illustrating a processing flow in a communication range estimation method according to a second exemplary embodiment of the present invention. FIG. 5 is a schematic diagram conceptually illustrating an example of a table. FIG. 6 is a diagram illustrating an example of an estimation result of a communication range. FIG. 7 is a diagram illustrating an example of an estimation result of a communication range. FIG. 8 is a diagram illustrating an example of an estimation result of a communication range. FIG. 9 is a schematic diagram illustrating an example of a three-dimensional distribution of a communication range. FIG. 10 is a graph illustrating an example of a change in the level and SNR of a received pulse signal over time. FIG. 11 is a graph illustrating an example of a change in the level and SNR of a received pulse signal over time. FIG. 12 is a graph illustrating a relationship between bandwidth and communication speed. FIG. 13 is a diagram illustrating an example of the configuration of a computer.

[0010] [First Exemplary Embodiment] A first exemplary embodiment of the present invention will be described in detail with reference to the drawings. This exemplary embodiment is a basic form of the exemplary embodiments described below.

[0011] The configuration of a communication range estimation device 10 according to this exemplary embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram illustrating the communication range estimation device 10 according to the first exemplary embodiment. The communication range estimation device 10 includes an information processing unit 11 and a memory 12, and is used to estimate a communication range using a sound wave signal in an underwater environment. The memory 12 stores a table T1. The table T1 represents a first relationship between a communication signal-to-noise ratio and a signal error rate. The information processing unit 11 executes a communication range estimation method.

[0012] Fig. 2 is a flow diagram showing the processing flow of the communication range estimation method S10 according to exemplary embodiment 1. The communication range estimation method S10 will be described below with reference to Fig. 2. As shown in Fig. 2, the communication range estimation method S10 includes a derivation process (step S11) and an estimation process (step S12).

[0013] (1) Derivation Process (Step S11) The information processing unit 11 derives a second relationship between the positional relationship between the transmitter and receiver and the signal-to-noise ratio based on the communication environment conditions in the underwater environment (Step S11).

[0014] (2) Estimation Process (Step S12) The information processing unit 11 estimates the communication range in the underwater environment based on the first relationship shown in the table T1 and the derived second relationship (Step S12).

[0015] As described above, the communication range estimation device 10 according to this exemplary embodiment is a communication range estimation device used to estimate a communication range using a sound wave signal in an underwater environment, and includes a memory 12 that stores a table T1 that represents a first relationship between a communication signal-to-noise ratio and a signal error rate, and an information processing unit 11. The information processing unit 11 executes a derivation process (S11) that derives a second relationship between a transmitting-receiving positional relationship between a transmitting side and a receiving side and a signal-to-noise ratio based on communication environment conditions in the underwater environment, and an estimation process (S12) that estimates the communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship. In the communication range estimation device 10, the use of the first and second relationships facilitates efficient estimation of the communication range in an underwater environment.

[0016] Furthermore, a communication range estimation method S10 according to this exemplary embodiment is a communication range estimation method used to estimate a communication range using a sound wave signal in an underwater environment, and includes a derivation process of deriving a second relationship between a positional relationship between a transmitter and a receiver and a signal-to-noise ratio based on communication environment conditions in the underwater environment, and an estimation process of estimating the communication range in the underwater environment based on a table representing a first relationship between the communication signal-to-noise ratio and a signal error rate and the derived second relationship. In the communication range estimation method S10, by using the first and second relationships, efficient estimation of the communication range in the underwater environment becomes easy.

[0017]

[0033] Exemplary embodiment 2 of the present invention will be described in detail with reference to the drawings. Note that components having the same functions as those described in exemplary embodiment 1 are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0018] Fig. 3 is a schematic diagram showing a communication range estimation system 100 according to exemplary embodiment 2. Fig. 4 is a flow diagram showing the processing flow of a communication range estimation method S100 according to exemplary embodiment 2.

[0019] The communication range estimation system 100 includes a communication range estimation device 110, a communication device 120, and a communication device 130.

[0020] The communication range estimation device 110 is a device used to estimate a communication range using a sound wave signal in an underwater environment, and includes an information processing unit 111 and a memory 112. The information processing unit 111 executes a communication range estimation method S100, which will be described later. The memory 112 stores a table T1, which will be described in detail later.

[0021] At least one of the communication devices 120, 130 is placed in an underwater environment (for example, a marine environment), and the communication devices 120, 130 communicate via signals through the underwater environment. The signals may be sound waves, radio waves, or light waves. In the following description, sound waves are used as an example of the signals.

[0022] The communication device 120 has a communication control unit 121 and a transmission / reception unit 122. The communication device 130 has a communication control unit 131 and a transmission / reception unit 132. The transmission / reception units 122 and 132 have, for example, sonar, which transmit and receive sound wave signals. The communication control units 121 and 131 control the transmission and reception of sound wave signals by the transmission / reception units 122 and 132, respectively.

[0023] The communication device 120 is connected to the communication range estimation device 110, and communicates with the communication device 130 based on the communication range estimation result by the communication range estimation device 110. Note that the communication device 130 may be connected to the communication range estimation device 110 or another communication range estimation device.

[0024] Here, for ease of understanding, the communication range estimation device 110 and the communication device 120 are shown separately, but the communication range estimation device 110 and the communication device 120 may be integrated into a single device, such as a communication range estimation / communication device. Furthermore, the communication range estimation device 110 and the communication device 120 may be mounted on a single surface or underwater propulsion device (e.g., a ship or a submarine) and moved on or underwater. As described below, the communication range estimation device 110 is lightweight and easily miniaturized, making it easy to mount on small ships and submarines.

[0025] Communication between the communication devices 120 and 130 is basically performed via the underwater environment between the water surface WS and the water bottom WB. At this time, the communication between the communication devices 120 and 130 can be divided into (1) a non-reflected signal P0 that is not reflected by either the water surface WS or the water bottom WB, (2) a water surface reflected signal P1 that is reflected by at least the water surface WS, and (3) a water bottom reflected signal P2 that is reflected by at least the water bottom WB.

[0026] For ease of understanding, the water surface reflection signal P1 and the water bottom reflection signal P2 are illustrated as signals reflected only once by the water surface WS or the water bottom WB, respectively. In reality, various signals exist, such as signals reflected multiple times by the water surface WS or the water bottom WB, and signals reflected by both the water surface WS and the water bottom WB. That is, a single signal transmitted from the transmitting side (one of the communication devices 120 and 130) travels through different paths (multipath) and is received as multiple received signals by the receiving side (the other of the communication devices 120 and 130). As a result, multiple received signals generated based on a single transmitted signal may arrive at the receiving side at different times. Hereinafter, these multiple received signals may be referred to as the first wave, second wave, ..., tenth wave, etc., in order of earliest arrival time.

[0027] In this way, in an underwater environment, a single transmitted signal splits into multiple overlapping signals that arrive at the receiving end. As a result, the waveform of the received signal at the receiving end becomes distorted, which tends to limit the communication range. The state of this received signal fluctuates spatially and temporally depending on the communication environment conditions in the underwater environment.

[0028] Examples of communication environment conditions in an underwater environment include the wind speed above the water surface WS, the depth H0 (water depth) of the water bottom WB, and the shape and sediment of the water bottom WB. These conditions have a significant impact on the reflection, attenuation, and scattering of sound waves at the water surface WS and the water bottom WB. Water temperature and salinity can also be considered as communication environment conditions. Water temperature or salinity has a significant impact on the speed of sound waves (sound velocity). Furthermore, if the water temperature or salinity has a spatial distribution, sound waves may be refracted, causing a change in the propagation direction.

[0029] In addition to the communication environment conditions in the underwater environment, the conditions on the transmitting and receiving sides also become an issue. For ease of understanding, the following description will be given assuming that the communication device 120 is the transmitting side and the communication device 130 is the receiving side.

[0030] The conditions on the transmitting side (transmission conditions) include the depth H1 of the communication device 120 (particularly the transceiver unit 122) and the transmission characteristics of the transceiver unit 122. The transmission characteristics of the transceiver unit 122 include the directivity of the sound waves transmitted from the transceiver unit 122 (for example, the vertical directionality width, the horizontal directionality width), the transmission pulse length, the transmission level, and the frequency.

[0031] The conditions on the receiving side (reception conditions) include the depth H2 of the communication device 130 (particularly the transceiver 132) and the reception characteristics of the transceiver 132. The reception characteristics of the transceiver 132 include directivity (for example, vertical directionality width and horizontal directionality width) and the bandwidth of receivable sound waves.

[0032] The conditions on the receiving side include the self-noise of the transmitting / receiving unit 132 and ambient noise. This ambient noise may include reverberation of the sound wave signal being communicated. In the derivation process (step S111) described below, the communication range estimation device 110 can calculate the signal-to-noise ratio (e.g., SNR) taking reverberation into consideration.

[0033] The communication range estimation device 110 has data on communication environment conditions, transmission conditions, and reception conditions, or can receive such data. For example, the communication range estimation device 110 may receive data corresponding to the communication environment conditions from a measuring instrument installed on a ship or submarine that carries the communication device 120.

[0034] The communication range in an underwater environment can include the range of communication from communication device 120 in one to three dimensions, such as distance, direction, and spatial region from communication device 120. When communication device 120 communicates with communication device 130, the communication range can include the distance L between communication devices 120 and 130, the difference between depths H1 and H2, and the direction from communication device 120 to communication device 130.

[0035] Table T1 shows a first relationship between a communication signal-to-noise ratio and a signal error rate. The communication signal-to-noise ratio is, for example, a signal-to-noise ratio (SNR). The signal error rate is, for example, a bit error rate (BER). Table T1 shows the first relationship (the relationship between the communication signal-to-noise ratio and the signal error rate) for a plurality of communication methods that differ in at least one of the communication modulation method and the communication equivalent method. Note that Table T1 may also show the first relationship (the relationship between the communication signal-to-noise ratio and the signal error rate) for a plurality of communication methods that differ in at least one of the communication modulation method, the communication equivalent method, and the error correction method. In the following, the SNR (signal-to-noise ratio) and the BER (bit error rate) are used as examples of the communication signal-to-noise ratio and the signal error rate.

[0036] FIG. 5 is a schematic diagram conceptually illustrating an example of Table T1. FIG. 5 shows the relationship between SNR and BER in various communication methods (modulation methods and equivalent methods). In FIG. 5, Table T1 is represented as a combination of Tables T1a to T1d, and Table T1d shows the relationship between SNR and BER when QPSK (Quadrature Phase Shift Keying), 8PSK (8-Phase Shift Keying), and 16QAM (Quadrature Amplitude Modulation) are used as modulation methods. Table T1 shows the relationship between SNR and BER in various communication methods (modulation methods and equivalent methods) while ignoring communication environment conditions (even if the details of the communication processing are unknown). The relationship between SNR and BER can be obtained as follows. For example, the relationship between SNR and BER can be obtained by measuring the SNR and BER in various communication methods while changing the communication distance using actual communication equipment. Instead of using actual communication equipment, the SNR and BER may be simulated using communication environment simulation software.

[0037] The communication range estimation method S100 will be described in detail below. As shown in Fig. 4, the communication range estimation method S100 includes a derivation process (step S111) and an estimation process (step S112).

[0038] (1) Derivation Process (Step S111) The information processing unit 111 derives a second relationship between the positional relationship between the transmitter and receiver (e.g., distance, direction) and the signal-to-noise ratio (e.g., SNR) between the transmitter (one of the communication devices 120 and 130) and the receiver (the other of the communication devices 120 and 130) based on communication environment conditions in the underwater environment (derivation process). That is, the correspondence relationship between the positional relationship between the transmitter and receiver and the SNR can be obtained based on appropriate communication environment conditions that may change.

[0039] For example, the SNR is derived by changing the positional relationship between the transmitter and receiver under predetermined communication environment conditions. For this derivation, for example, sound wave propagation simulation software (e.g., RevSum: catalog software manufactured by NEC) that simulates the propagation of sound waves can be used.

[0040] More specifically, in the derivation process, the information processing unit 111 can derive the second relationship (the relationship between the positional relationship between the transmitter and receiver and the signal-to-noise ratio) for any one of a plurality of received pulse signals that are received by the receiving unit (e.g., the other of the communication devices 120 and 130) in response to one transmitted pulse signal transmitted from the transmitting unit (e.g., one of the communication devices 120 and 130) and that have different required times from the transmitting unit. The use of pulse signals facilitates the derivation of the second relationship, making it easier to reduce the weight and size of the communication range estimation device 110. In other words, assuming a variety of waveforms, complex processing including a convolution operation using impulse responses is required, which increases the amount of processing and the processing speed of the information processing unit 111. In other words, this results in an increase in the size of the communication range estimation device 110 and a decrease in the speed of the derivation process (step S111).

[0041] In acoustic wave communications, it is common to use a relatively continuous acoustic signal rather than a pulse. In this case, the transmitted signal reaches the receiving end via multiple paths, which can cause overlapping and distort the signal waveform. For this reason, it is preferable to use, for example, the signal that arrives first (the first wave). By using an impulse signal, it is possible to simulate the first signal (the first wave).

[0042] In this case, it is preferable to select a received pulse based on (1) the communication path and (2) at least one of the signal strength and waveform state. The waveform state includes waveform disturbance. That is, a received pulse may be selected based on waveform disturbance. Basically, the received pulse signal (first wave) that arrives first at the receiving side often has a high signal strength and is preferable. However, the waveform of the first wave may be disturbed due to signal phase inversion caused by signal reflection at the water surface WS and the water bottom WB. That is, the order in which the signals arrive does not necessarily correspond to whether the signal is good or bad.

[0043] For example, the transmitted signal may be reflected by the water surface WS and reach the receiver in the first wave, by the second wave without being reflected by either the water surface WS or the water bottom WB, or by the third wave by the water bottom WB and reach the receiver. In such a case, even the second wave is likely to have good signal strength and waveform. On the other hand, even if the signal is reflected by the water surface WS and the water bottom WB, the signal strength may be high and the waveform may not be significantly distorted.

[0044] That is, one received pulse signal can be selected based on the communication path, for example, a first received pulse signal that passes through a first communication path that is not reflected by either the water surface WS or the water bottom WB can be selected as the first received pulse signal.

[0045] The first received pulse signal can be selected based on its signal strength or waveform condition (e.g., waveform disturbance). For example, the first received pulse signal can be a second received pulse signal that has a stronger signal strength or less waveform disturbance from the transmitted pulse signal than a first received pulse signal that (1) passes through a second communication path that is reflected by either the water surface WS or the water bottom WB, and (2) passes through a first communication path that is not reflected by either the water surface WS or the water bottom WB.

[0046] Here, it is preferable to consider the reverberation of the transmitted sound wave signal. Reverberation occurs when sound waves hit the water surface WS or the water bottom WB and are scattered. At this time, the strength of scattering varies depending on the characteristics of the water surface WS and the water bottom WB (for example, the wind speed above the water surface WS and the bottom sediment of the water bottom WB). Furthermore, the reverberation is large when the distance from the transmitting side is small, and small when the distance is large. As a result, when the distance between the transmitting side and the receiving side is small, the receiving side is easily affected by reverberation. In other words, by considering the effect of reverberation, it is possible to accurately estimate the SNR at close range.

[0047] (2) Estimation Process (Step S112) The information processing unit 111 estimates the communication range in the underwater environment based on the first relationship shown in the table T1 and the second relationship derived in step S111 (estimation process).

[0048] At this time, the information processing unit 111 may estimate the communication range in the underwater environment in the estimation process based on the allowable range of the communication signal-to-noise ratio determined based on the first relationship and the second relationship.

[0049] Determination of the allowable range of communication signal-to-noise ratio (SNR) based on the first relationship will be described below. The allowable range of SNR can be determined based on the allowable range of BER and the first relationship. First, the allowable range of BER can be determined depending on the use of the signal to be communicated. For example, if the use of communication is control, the lower limit of the allowable range of BER can be set to 10 －６ On the other hand, if the purpose of communication is to transmit images, some pixel loss is allowed, so the lower limit of the allowable range of BER is set to 10 －４ Next, the allowable range of SNR can be determined based on the first relationship so as to correspond to the determined allowable range of BER. In this way, it is possible to determine the underwater communication range in which the SNR falls within the allowable range for a desired communication method.

[0050] Here, the allowable range of BER can be determined by the user or the information processing unit 111. That is, the allowable range of SNR can be determined by either of the following methods (1) or (2). The allowable range of SNR may be determined by either of these methods (1) or (2).

[0051] (1) The user determines the allowable range of BER based on the type of communication in the transmitting / receiving unit 122, and the information processing unit 111 sets the allowable range of SNR based on the allowable range of BER. For example, the user determines the lower limit of the allowable range of BER based on the content of communication (transmission of image information, transmission of audio information, etc.) and inputs or transmits it to the information processing unit 111. As a result, the allowable range of SNR is determined.

[0052] (2) The information processing unit 111 determines the allowable BER range based on the type of communication in the transmission / reception unit 122, and sets the allowable SNR range based on the allowable BER range. For example, the communication control unit 121 grasps the communication content (transmission of image information, transmission of audio information, etc.) and determines the lower limit of the allowable BER range based on the communication content. As a result, the allowable SNR range is determined. Note that the allowable BER range based on the communication content may be determined by referring to a table or the like that shows the correspondence between the communication content and the allowable BER range (especially the lower limit of the allowable BER range).

[0053] 6 to 9 are diagrams showing examples of the results of estimating the communication range.

[0054] 6 shows the relationship between the distance L and the SNR for the first wave S1 to the tenth wave S10. The minimum value of the allowable range of SNR (minimum allowable SNR value) SNR0 is shown. In this case, the communication range for the second wave S2 is a distance L range of 0 to L2. The communication range for the third wave S3 is a distance L range of L31 to L32.

[0055] 7 shows the relationship between distance L and SNR for each communication method (modulations A to C). The minimum value of the allowable range of SNR (minimum allowable SNR 0) is shown. In this case, the communication ranges for modulations A, B, and C are such that the distance L ranges from 0 to La, Lb, and Lc, respectively.

[0056] Fig. 8 shows the relationship between the distance L and depth H and the SNR. In this case, the area AR within the dashed line is the communication range. Fig. 9 shows the relationship between the distance L and depth H and the SNR. Although not explicitly shown here, in this case too, the communication range is determined in relation to the minimum allowable SNR value SNR0, as in Fig. 8. As shown in Fig. 10, the communication range can also be represented three-dimensionally.

[0057] 11 to 13 are graphs showing an example of temporal changes in the level and SNR of a received pulse signal.

[0058] 11 shows the temporal change in signal level at the receiving side when the distance L is 200 m. Graph CH1a shows the levels of water surface reverberation Z1, water bottom reverberation Z2, volume reverberation Z3, combined reverberation Z0, and the received signals SA of the first to tenth waves. Graph CH1b shows the temporal change in the SNR of the received pulse signals SA of the first to tenth waves. That is, the SNRs of multiple received pulse signals SA are calculated using combined reverberation Z0, which is the sum of water surface reverberation Z1, water bottom reverberation Z2, and volume reverberation Z3, as noise.

[0059] 12 shows the change in signal level over time on the receiving side when the distance L is 1000 m. Graphs CH2a and CH2b correspond to graphs CH1a and CH1b in FIG.

[0060] 13 shows the distance dependence of the levels and SNR of the first wave S1 to the tenth wave S10. Graph LV shows the distance dependence of the levels of the first wave S1 to the tenth wave S10. Graph SNR shows the distance dependence of the SNR of S1 to S10.

[0061] As described above, the relationship between the SNR and distance on the receiving side for the first wave S1 to the tenth wave S10 can be derived, taking reverberation into consideration. As shown in the SNR graph, the communication range for the first wave S1 is a range of distance L from 0 to L1, and the communication range for the third wave S3 is a range of distance L from L31 to L32.

[0062] As described above, the communication range estimation device 110 derives the second relationship between the positional relationship between the transmitter and receiver and the signal-to-noise ratio based on the communication environment conditions in the underwater environment, and estimates the communication range in the underwater environment based on the table representing the first relationship between the communication signal-to-noise ratio and the signal error rate and the derived second relationship. As a result, by using the first and second relationships, it becomes easy to efficiently estimate the communication range in the underwater environment.

[0063] (Modification) A modification of the communication range estimation device 110 will now be described.

[0064] The information processing unit 111 may present the communication speed. The relationship between the communication speed and the bandwidth in a noisy communication channel is expressed by the following equation (1) (Shannon-Hartley theorem): C=W*log ２ (1+γ) ...Formula (1) C: Communication speed [bps] W: Bandwidth [Hz] γ: SNR (amplitude ratio)

[0065] That is, the information processing unit 111 calculates the SNR, and applies the bandwidth W, which is determined by this SNR and the device performance of the transmitting / receiving unit 122, to equation (1), thereby calculating the communication speed C. Fig. 14 is a graph showing the relationship between bandwidth and communication speed. The communication speeds C for communication devices A1 to A3 are shown.

[0066] In the above embodiment, the information processing unit 111 estimates the communication range in an underwater environment based on the first relationship (the relationship between SNR and BER) shown in Table T1 (estimation process). The information processing unit 111 may estimate the communication speed instead of or in addition to the communication range. Furthermore, the communication speed estimation may be performed in parallel with the communication range estimation.

[0067] For example, the memory 112 can store a table representing the relationship between the SNR and the communication speed C calculated from the SNR, instead of or together with the table T1 representing the first relationship. Using this table makes it easier for the information processing unit 11 to estimate the communication speed. As a result, the information processing unit 11 can calculate the communication speed, for example, according to the positional relationship between the transmitter and receiver (e.g., the distance and direction of the receiver relative to the transmitter).

[0068] Here, in calculating the communication speed, a table showing the relationship between SNR and communication speed C may be used instead of equation (1). Equation (1) is a theoretical value showing the maximum communication capacity (throughput) and is one guideline showing the relationship between SNR and communication speed C. For the same SNR, the actual communication speed varies depending on the modulation method, coding rate, guard interval time, and communication method such as MIMO. In other words, by calculating or actually measuring the SNR for various communication methods and creating a table showing the relationship between SNR and communication speed C, it is possible to more accurately calculate the communication speed.

[0069] Based on the communication speed C3 of 16,000 [bps] and bandwidth W1 of 8,000 [Hz] for communication device A3, the communication speeds C2 and C1 of communication devices A2 and A1 in the same communication environment can be predicted. From the communication speed C3 and bandwidth W3 of communication device A3, an SNR of 3.0 can be calculated. Then, from this SNR and the bandwidths W2 and W1 of communication devices A2 and A1, the communication speeds C2 and C1 of communication devices A2 and A1 can be calculated.

[0070] [Example of Software Implementation] Some or all of the functions of the information processing unit 111 may be implemented by hardware such as an integrated circuit (IC chip), or may be implemented by software.

[0071] In the latter case, the information processing unit 111 is realized, for example, by a computer that executes instructions of a program, which is software that realizes each function. An example of such a computer (hereinafter referred to as computer C) is shown in FIG. 15. The computer C includes, for example, at least one processor C1 and at least one memory C1. The memory C1 stores a program P for operating the computer C as the information processing unit 111. In the computer C, the processor C1 reads and executes the program P from the memory C1, thereby realizing each function of the information processing unit 111.

[0072] The processor C1 may be, for example, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a micro processing unit (MPU), a floating point number processing unit (FPU), a physics processing unit (PPU), a tensor processing unit (TPU), a quantum processor, a microcontroller, or a combination thereof. The memory C1 may be, for example, a flash memory, a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof.

[0073] The computer C may further include a RAM (Random Access Memory) for expanding the program P during execution and for temporarily storing various data. The computer C may also include a communication interface for transmitting and receiving data to and from other devices. The computer C may also include an input / output interface for connecting input / output devices such as a keyboard, a mouse, a display, and a printer.

[0074] The program P can also be recorded on a non-transitory, tangible recording medium M that can be read by the computer C. Such a recording medium M can be, for example, a tape, a disk, a card, a semiconductor memory, or a programmable logic circuit. The computer C can acquire the program P via such a recording medium M. The program P can also be transmitted via a transmission medium. Such a transmission medium can be, for example, a communication network or broadcast waves. The computer C can also acquire the program P via such a transmission medium.

[0075] [Additional Note 1] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. For example, embodiments obtained by appropriately combining the technical means disclosed in the above-described embodiments are also included in the technical scope of the present invention.

[0076] [Additional Note 2] Part or all of the above-described embodiment can also be described as follows: However, the present invention is not limited to the following described aspects.

[0077] (Supplementary Note 1) A communication range estimation device is a communication range estimation device used to estimate a communication range using a sound wave signal in an underwater environment, and includes: a memory that stores a table that represents a first relationship between a communication signal-to-noise ratio and a signal error rate; and an information processing unit, wherein the information processing unit executes a derivation process that derives a second relationship between a transmitting and receiving positional relationship and a signal-to-noise ratio based on communication environment conditions in the underwater environment; and an estimation process that estimates a communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship.

[0078] According to the above configuration, it is possible to efficiently estimate the communication range in an underwater environment based on the table that represents the first relationship between the communication signal-to-noise ratio and the signal error rate.

[0079] (Supplementary Note 2) In the communication range estimation device of Supplementary Note 1, in the derivation process, the information processing unit derives the second relationship for one of a plurality of received pulse signals that are received by the receiving side in response to one transmitted pulse signal transmitted from the transmitting side and that have different required times from the transmitting side.

[0080] According to the above configuration, the second relationship between the positional relationship between the transmitter and receiver and the signal-to-noise ratio can be efficiently derived using pulse signals.

[0081] (Supplementary Note 3) The communication range estimation device according to Supplementary Note 2, wherein the first received pulse signal is selected based on a communication path.

[0082] According to the above configuration, it becomes easy to select a received pulse signal with good signal strength and waveform based on the communication path.

[0083] (Supplementary Note 4) The communication range estimation device according to Supplementary Note 2, wherein the first received pulse signal is selected based on signal strength or waveform state.

[0084] According to the above configuration, it becomes easy to select a received pulse signal with good signal strength and waveform based on the signal strength or waveform state.

[0085] (Supplementary Note 5) The communication range estimation device according to any one of Supplementary Notes 1 to 4, wherein the information processing unit estimates the communication range in the underwater environment based on an allowable range of a communication signal-to-noise ratio determined based on the first relationship and the second relationship in the estimation process.

[0086] According to the above configuration, the communication range in an underwater environment can be efficiently estimated based on the determined allowable range of the communication signal-to-noise ratio.

[0087] (Supplementary Note 6) The communication range estimation device according to any one of Supplementary Notes 1 to 5, wherein the table represents the first relationship in a plurality of communication methods that differ in at least one of a communication modulation method and a communication equivalent method.

[0088] According to the above configuration, it is possible to efficiently estimate the communication range in an underwater environment for a plurality of communication methods.

[0089] (Supplementary Note 7) The communication range estimation device according to claim 1, wherein the underwater environment is a marine environment, and the communication environment conditions are at least one of wind speed, depth, water depth, and bottom sediment.

[0090] According to the above configuration, it is possible to efficiently estimate the communication range in an underwater environment for at least one of the wind speed, depth, water depth, and bottom sediment in the marine environment.

[0091] (Supplementary Note 8) A communication range estimation method used to estimate a communication range using a sound wave signal in an underwater environment, the communication range estimation method including: a derivation process that derives a second relationship between a positional relationship between a transmitter and a receiver and a signal-to-noise ratio based on communication environment conditions in the underwater environment; and an estimation process that estimates the communication range in the underwater environment based on a table that represents a first relationship between the communication signal-to-noise ratio and a signal error rate, and the derived second relationship.

[0092] According to the above configuration, it is possible to efficiently estimate the communication range in an underwater environment based on the table that represents the first relationship between the communication signal-to-noise ratio and the signal error rate.

[0093] (Supplementary Note 9) A communication range estimation program that causes a computer to function as the communication range estimation device according to claim 1, the communication range estimation program causing the computer to execute the derivation process and the estimation process.

[0094] (Supplementary Note 10) A communication range estimation system comprising: a communication device that transmits and receives sound signals via an underwater environment; and a communication range estimation device that estimates a communication range in the underwater environment, wherein the communication range estimation device comprises a memory that stores a table that represents a first relationship between a communication signal-to-noise ratio and a signal error rate; and an information processing unit, wherein the information processing unit performs a derivation process that derives a second relationship between a positional relationship between a transmitter and a receiver and a signal-to-noise ratio when the communication device is either a transmitter of a sound signal or a receiver of a signal, based on communication environment conditions in the underwater environment; and an estimation process that estimates a communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship.

[0095] According to the above configuration, the communication range in an underwater environment can be efficiently estimated based on the table representing the first relationship between the communication signal-to-noise ratio and the signal error rate. In addition, by installing the communication device and the communication range estimation device on a small ship or submersible, the communication range can be appropriately estimated according to the communication environment conditions in the underwater environment.

[0096] (Supplementary Note 11) A communication range estimation device used to estimate a communication range using a sound wave signal in an underwater environment, the communication range estimation system comprising: a memory that stores a table that represents a first relationship between a communication signal-to-noise ratio and a signal error rate; and at least one processor, wherein the processor executes a derivation process that derives a second relationship between a transmitting-receiving positional relationship between a transmitting side and a receiving side and a signal-to-noise ratio based on a communication environment condition in the underwater environment; and an estimation process that estimates the communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship.

[0097] The communication range estimation system may further include a memory for storing a program, and the memory may store a program for causing the processor to execute the derivation process and the estimation process. The program may also be recorded on a computer-readable, non-transitory, tangible recording medium.

[0098] 100 Communication range estimation system 10, 110 Communication range estimation device 11, 111 Information processing unit 12, 112 Memory 120130 Communication device 121, 131 Communication control unit 122, 132 Transmitting / receiving unit S10, S100 Communication range estimation method T1 Table

Claims

1. A communication range estimation device used to estimate a communication range using a sound wave signal in an underwater environment, comprising: a memory that stores a table that represents a first relationship between a communication signal-to-noise ratio and a signal error rate; an information processing unit, The information processing unit a derivation process for deriving a second relationship between a positional relationship between a transmitter and a receiver and a signal-to-noise ratio based on a communication environment condition in the underwater environment; an estimation process for estimating a communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship; A communication range estimation device that executes the above.

2. In the derivation process, the information processing unit 2. The communication range estimation device according to claim 1, wherein the second relationship is derived for one of a plurality of received pulse signals that are received by the receiving side in response to one transmitted pulse signal transmitted from the transmitting side and that have different required times from the transmitting side.

3. The communication range estimation device according to claim 2 , wherein the one received pulse signal is selected based on a communication path.

4. The communication range estimation device according to claim 2 , wherein the one received pulse signal is selected based on signal strength or waveform state.

5. The information processing unit, in the estimation process, The communication range estimation device according to claim 1 , wherein the communication range in the underwater environment is estimated based on an allowable range of a communication signal-to-noise ratio determined based on the first relationship and the second relationship.

6. The communication range estimation device according to claim 1 , wherein the table represents the first relationship for a plurality of communication methods that differ in at least one of a communication modulation method and a communication equalization method.

7. the aquatic environment is a marine environment; The communication range estimation device according to claim 1 , wherein the communication environment conditions are at least one of wind speed, depth, water depth, and bottom sediment.

8. A communication range estimation method used to estimate a communication range using a sound wave signal in an underwater environment, comprising: a derivation process for deriving a second relationship between a positional relationship between a transmitter and a receiver and a signal-to-noise ratio based on a communication environment condition in the underwater environment; an estimation process for estimating a communication range in the underwater environment based on a table representing a first relationship between the communication signal-to-noise ratio and the signal error rate and the derived second relationship; A communication range estimation method comprising:

9. A communication range estimation program that causes a computer to function as the communication range estimation device according to claim 1, a communication range estimation program that causes the computer to execute the derivation process and the estimation process;

10. a communication device for transmitting and receiving acoustic signals through an underwater environment; a communication range estimation device that estimates a communication range in the underwater environment, The communication range estimation device a memory that stores a table that represents a first relationship between a communication signal-to-noise ratio and a signal error rate; an information processing unit, The information processing unit a derivation process for deriving a second relationship between a positional relationship between a transmitter and a receiver and a signal-to-noise ratio when the communication device is either a transmitter of a sound wave signal or a receiver of the signal, based on communication environment conditions in the underwater environment; an estimation process for estimating a communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship; A communication range estimation system that performs the above.