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

Technical Field

[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.

Background Art

[0002] When communicating through water, it is preferable for maintaining the communication state if the communicable range can be appropriately predicted. This is because the communication range in water varies depending on environmental conditions, and there is no guarantee that a good communication state will continue.

[0003] Patent Document 1 discloses a technique for estimating the symbol error rate of communication by propagation simulation in acoustic communication between a surface station and an underwater vehicle, and estimating the positions of the surface station and the underwater vehicle where the symbol error rate is below the reference when the symbol error rate is greater than the reference.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when trying to predict the communication range (for example, the appropriate direction and distance between a surface station and an underwater vehicle) using the technique 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 view of the above problems, and an example of its object 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 achieve efficient prediction of the communication range.

Means for Solving the Problems

[0007] A communication range estimation device according to one aspect of the present invention is a communication range estimation device used for estimating the communication range using sound wave signals in an underwater environment, comprising: a memory that stores a table representing a first relationship between the communication signal-to-noise ratio and the signal error rate; and an information processing unit, wherein the information processing unit performs a derivation process that derives a second relationship between the positional relationship between the transmitting and receiving side and the signal-to-noise ratio based on the 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. [Effects of the Invention]

[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 predicting the communication range underwater. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows a communication range estimation device according to an exemplary embodiment 1 of the present invention. [Figure 2] This is a flowchart illustrating the processing flow of the communication range estimation method according to Exemplary Embodiment 1 of the present invention. [Figure 3] This figure shows a communication range estimation system according to an exemplary embodiment 2 of the present invention. [Figure 4] This is a flowchart illustrating the processing flow of the communication range estimation method according to exemplary embodiment 2 of the present invention. [Figure 5] This is a schematic diagram conceptually representing an example of a table. [Figure 6] This figure shows an example of the estimated communication range. [Figure 7] This figure shows an example of the estimated communication range. [Figure 8] This figure shows an example of the estimated communication range. [Figure 9] This figure shows an example of the estimated communication range. [Figure 10]It is a schematic diagram showing an example of the three-dimensional distribution of the communication range. [Figure 11] It is a graph showing an example of the temporal changes in the level and SNR of the received pulse signal. [Figure 12] It is a graph showing an example of the temporal changes in the level and SNR of the received pulse signal. [Figure 13] It is a graph showing an example of the temporal changes in the level and SNR of the received pulse signal. [Figure 14] It is a graph showing the relationship between the bandwidth and the communication speed. [Figure 15] It is a diagram showing an example of the configuration of a computer.

Mode for Carrying Out the Invention

[0010] 〔Exemplary Embodiment 1〕 Exemplary Embodiment 1 of the present invention will be described in detail with reference to the drawings. This exemplary embodiment is a basic form for the exemplary embodiments described later.

[0011] The configuration of the communication range estimation device 10 according to this exemplary embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram showing the communication range estimation device 10 according to Exemplary Embodiment 1. The communication range estimation device 10 includes an information processing unit 11 and a memory 12, and is used for estimating the communication range by acoustic signals in an underwater environment. The memory 12 stores a table T1. The table T1 represents a first relationship between the communication signal-to-noise ratio and the signal error rate. The information processing unit 11 executes a communication range estimation method.

[0012] FIG. 2 is a flowchart showing the processing flow in the communication range estimation method S10 according to Exemplary Embodiment 1. Hereinafter, the communication range estimation method S10 will be described based on FIG. 2. As shown in FIG. 2, the communication range estimation method S10 has 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 transmission / reception position relationship and the signal-to-noise ratio between the transmission side and the reception side 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 represented 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 for estimating the communication range by acoustic signals in an underwater environment, and includes a memory 12 that stores a table T1 representing 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 performs a derivation process (S11) of deriving a second relationship between the transmission / reception position relationship and the signal-to-noise ratio between the transmission side and the reception side based on the communication environment conditions in the underwater environment, and an estimation process (S12) of estimating 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, by using the first and second relationships, it becomes easy to efficiently estimate the communication range in the underwater environment.

[0016] Also, the communication range estimation method S10 according to this exemplary embodiment is a communication range estimation method used for estimating the communication range by acoustic signals in an underwater environment, and includes a derivation process of deriving a second relationship between the position relationship between the transmission side and the reception side and the signal-to-noise ratio based on the 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 the signal error rate and the derived second relationship. In the communication range estimation method S10, by using the first and second relationships, it becomes easy to efficiently estimate the communication range in the underwater environment.

[0017] 〔Exemplary Embodiment 2〕 An exemplary embodiment 2 of the present invention will be described in detail with reference to the drawings. Components having the same function as those described in exemplary embodiment 1 will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0018] Figure 3 is a schematic diagram representing the communication range estimation system 100 according to exemplary embodiment 2. Figure 4 is a flowchart showing the processing flow in the 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 used to estimate the communication range using sound wave signals in an underwater environment, and includes an information processing unit 111 and a memory 112. The information processing unit 111 executes the communication range estimation method S100, which will be described later. The memory 112 stores table T1. Details of table T1 will be described later.

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

[0022] Communication device 120 has a communication control unit 121 and a transmitting / receiving unit 122. Communication device 130 has a communication control unit 131 and a transmitting / receiving unit 132. The transmitting / receiving units 122 and 132 have, for example, sonar that transmit and receive sound wave signals. The communication control units 121 and 131 control the transmission and reception of sound wave signals by the transmitting / receiving 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 from the communication range estimation device 110. The communication device 130 may be connected to the communication range estimation device 110 or another communication range estimation device.

[0024] Here, for the sake of clarity, the communication range estimation device 110 and the communication device 120 are shown separately. However, the communication range estimation device 110 and the communication device 120 may be integrated as a single device, for example, 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 submarine) and moved on or underwater. As will be described later, the communication range estimation device 110 is lightweight and easily miniaturized, making it easy to mount on small ships and submarines.

[0025] Communication between communication devices 120 and 130 is basically conducted via the underwater environment between the water surface WS and the seabed WB. In this case, communication between communication devices 120 and 130 can be divided into (1) an unreflected signal P0 that is not reflected by either the water surface WS or the seabed WB, (2) a water surface reflected signal P1 that is reflected by at least the water surface WS, and (3) a seabed reflected signal P2 that is reflected by at least the seabed WB.

[0026] For the sake of clarity, the surface reflection signal P1 and the bottom reflection signal P2 are shown here as signals reflected only once by the surface wave WS or bottom wave B, respectively. In reality, there are various types of signals, such as signals reflected multiple times by the surface wave WS or bottom wave B, or signals reflected by both the surface wave WS and bottom wave B. That is, one signal transmitted from the transmitting side (one of the communication devices 120 or 130) travels through different paths (multipath) and is received by the receiving side (the other of the communication devices 120 or 130) as multiple received signals. As a result, multiple received signals generated from a single transmitted signal may arrive at the receiving side at different times. Hereafter, these multiple received signals may be referred to as the 1st wave, 2nd wave, ... 10th wave, etc., in order of their arrival time.

[0027] Thus, in an underwater environment, a single transmitted signal splits into multiple signals, which overlap and reach the receiver. As a result, the waveform of the received signal at the receiver becomes distorted, and the communication range tends to be limited. This state of the received signal varies spatially and temporally depending on the communication environment conditions in the underwater environment.

[0028] Examples of communication environment conditions in an underwater environment include wind speed on the water surface (WS), the depth H0 (water depth) of the seabed (WB), and the shape and type of the seabed (WB). These conditions significantly affect the reflection, attenuation, and scattering of sound waves at the water surface (WS) and seabed (WB). Water temperature and salinity can also be considered communication environment conditions. Water temperature or salinity significantly affects the speed of sound. Furthermore, if water temperature or salinity has a spatial distribution, sound waves may refract, changing their propagation direction.

[0029] In addition to the communication environment conditions in an underwater setting, the conditions on both the transmitting and receiving sides are also important. For the sake of clarity, here we will explain using communication device 120 as the transmitting side and communication device 130 as the receiving side.

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

[0031] The receiving conditions (reception conditions) include the depth H2 of the communication device 130 (particularly the transmitting / receiving unit 132) and the reception characteristics of the transmitting / receiving unit 132. The reception characteristics of the transmitting / receiving unit 132 include the directivity (for example, vertical directivity width and horizontal directivity width) and the bandwidth of the sound waves that can be received.

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

[0033] The communication range estimation device 110 may have data on communication environment conditions, transmission conditions, and reception conditions, or may be provided with such data. For example, the communication range estimation device 110 may receive data corresponding to communication environment conditions from measuring instruments installed on a ship or submarine equipped with the communication device 120.

[0034] In an underwater environment, the communication range can be defined as the one- to three-dimensional range from the communication device 120, such as distance from the communication device 120, direction, and spatial domain. When the communication device 120 communicates with the communication device 130, the communication range can be defined as the distance L between the communication devices 120 and 130, the difference in depths H1 and H2, and the direction from the communication device 120 toward the communication device 130.

[0035] Table T1 shows the first relationship between the signal-to-noise ratio and the signal error rate. The signal-to-noise ratio is, for example, the signal-to-noise ratio (SNR). The signal error rate is, for example, the bit error rate (BER). Table T1 shows the modulation scheme of the communication and the communication Equalization This table shows the first relationship (relationship between the signal-to-noise ratio and the signal error rate) in multiple communication systems where at least one of the methods is different. Equalization This may represent the first relationship (relationship between signal-to-noise ratio and signal error rate) in multiple communication systems that differ in at least one of their methods and error correction methods. Below, we will explain using SNR (signal-to-noise ratio) and BER (bit error rate) as examples of signal-to-noise ratio and signal error rate.

[0036] Figure 5 is a schematic diagram conceptually representing an example of Table T1. Figure 5 shows various communication methods (modulation methods and EqualizationThe relationship between SNR and BER in various communication methods (modulation methods and) is shown. In Figure 5, Table T1 is represented as a combination of Tables T1a to T1d, and Table T1d shows the relationship between SNR and BER when using QPSK (Quadratur e Phase Shift Keying), 8PSK (8-Phase Shift Keying), and 16QAM (Quadrature Amplitude Modulation) as modulation methods. Table T1 abstracts away the communication environment conditions (even if the details of the communication process are unknown) and shows the relationship between SNR and BER in various communication methods (modulation methods and Equalization The relationship between SNR and BER in a given communication scheme is shown. The relationship between SNR and BER can be obtained as follows: For example, by using actual communication equipment and varying the communication distance while measuring SNR and BER in various communication schemes, the relationship between SNR and BER can be obtained. Alternatively, instead of actual communication equipment, communication environment simulation software can be used to simulate SNR and BER.

[0037] The details of the communication range estimation method S100 are described below. As shown in Figure 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 transmission-reception positional relationship (e.g., distance, direction) and the signal-to-noise ratio (e.g., SNR) between the transmitting side (one of the communication devices 120, 130) and the receiving side (the other of the communication devices 120, 130) based on the communication environment conditions in the underwater environment (derivation process). In other words, the correspondence between the transmission-reception positional relationship and the SNR can be determined based on appropriate and changing communication environment conditions.

[0039] For example, the signal-to-noise ratio (SNR) can be derived by changing the relative positions of the transmitter and receiver under predetermined communication environment conditions. For this derivation, for example, sound wave propagation simulation software (e.g., RevSum: NEC catalog software) can be used to simulate the propagation of sound waves.

[0040] More specifically, in the derivation process, the information processing unit 111 can derive a second relationship (relationship between transmission / reception position relationship and signal-to-noise ratio) for one of several received pulse signals that are received at the receiving side (e.g., the other communication device 120 or 130) in response to one transmitted pulse signal sent from the transmitting side (e.g., one of the communication devices 120 or 130), and that have different transmission times from the transmitting side. By using pulse signals, the derivation of the second relationship becomes easier, and the communication range estimation device 110 can be made lighter and smaller. In other words, assuming a variety of waveforms would require complex processing including convolution operations based on impulse responses, which would increase the processing load and processing speed of the information processing unit 111, or in other words, lead to a larger communication range estimation device 110 and a decrease in the speed of the derivation process (step S111).

[0041] In sound wave communication, it is customary to use a somewhat continuous sound wave signal rather than a pulse. In this case, since the transmitted signal reaches the receiver via multipath, the signals may overlap and the waveform may be distorted. For this reason, it is preferable to use, for example, the first signal that arrives (the first wave). By using an impulse signal, it is possible to simulate the first signal that arrives (the first wave).

[0042] In this case, it is preferable to select a received pulse based on (1) the communication path, or (2) the signal strength or waveform state, or at least one of the following. The waveform state includes waveform distortion. That is, a received pulse may be selected based on waveform distortion. Basically, it is often preferable that the first received pulse signal (first wave) that reaches the receiving side has a high signal strength. However, the waveform of the first wave may be distorted due to signal inversion caused by signal reflection at the water surface WS and the seabed WB. In other words, the order in which signals arrive and the quality of the signals do not necessarily coincide.

[0043] For example, a transmitted signal might reach the receiver via the water surface wave shield (WS) in the first wave, reach the receiver via the second wave without being reflected by either the water surface WS or the seabed wave bridge (WB) in the second wave, and reach the receiver via the seabed wave bridge (WB) in the third wave. In such a case, even the second wave is likely to have good signal strength and waveform. On the other hand, even if reflected by both the water surface WS and the seabed wave bridge, the signal strength may be high and the waveform distortion may not be significant.

[0044] In other words, the first received pulse signal can be selected based on the communication path. For example, the 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 the first received pulse signal.

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

[0046] Here, it is preferable to consider the reverberation of the transmitted sound wave signal. Reverberation occurs when sound waves strike the water surface (WS) or the seabed (WB) and scatter. At this time, the intensity of scattering changes depending on the characteristics of the water surface (WS) and seabed (WB) (for example, wind speed on the water surface (WS), and the type of seabed (WB)). Also, the reverberation is greater when the distance from the transmitter is small, and less when the distance is large. As a result, when the distance between the transmitter and receiver is small, the receiver is more susceptible to the effects of reverberation. In other words, by considering the effect of reverberation, it becomes possible to estimate the accurate SNR at short distances.

[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 table T1 and the second relationship derived in step S111 (estimation process).

[0048] In this case, 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] The following explains how to determine the acceptable range of the signal-to-noise ratio (SNR) based on the first relationship. The acceptable range of SNR can be determined based on the acceptable range of BER and the first relationship. First, the acceptable range of BER can be determined according to the application of the signal being communicated. For example, if the communication is for control, the lower limit of the acceptable range of BER can be set to 10 in order to ensure reliability. -6 This makes it relatively small. On the other hand, if the communication is for image transmission, some pixel loss is acceptable, so the lower limit of the acceptable range for BER is set to 10 -4 This can be made relatively large. Next, based on the first relationship, the acceptable range of SNR can be determined to correspond to the determined acceptable range of BER. In this way, the underwater communication range in which the SNR is within the acceptable range for the desired communication scheme can be determined.

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

[0051] (1) The user determines the acceptable range of BER based on the type of communication at the transmitting / receiving unit 122, and the information processing unit 111 sets the acceptable range of SNR based on that acceptable range of BER. For example, the user determines the lower limit of the acceptable range of BER based on the content of the 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 acceptable range of SNR is determined.

[0052] (2) The information processing unit 111 determines the acceptable range of BER based on the type of communication in the transmitting / receiving unit 122, and the information processing unit 111 sets the acceptable range of SNR based on that acceptable range of BER. 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 acceptable range of BER based on that communication content. As a result, the acceptable range of SNR is determined. The acceptable range of BER 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 acceptable range of BER (especially the lower limit of the acceptable range of BER).

[0053] Figures 6 to 9 show examples of estimated communication range results.

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

[0055] Figure 7 shows the relationship between distance L and SNR in the communication methods (modulation A to C). The minimum acceptable value of SNR (minimum acceptable SNR 0) is shown. In this case, the communication range for modulations A, B, and C is from distance L 0 to La, Lb, and Lc, respectively.

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

[0057] Figures 11 to 13 are graphs illustrating examples of the temporal changes in the level and SNR of a received pulse signal.

[0058] Figure 11 shows the temporal change in the signal level at the receiving end at a distance L of 200m. Graph CH1a shows the levels of surface reverberation Z1, underwater reverberation Z2, volume reverberation Z3, combined reverberation Z0, and the received signals SA of waves 1 to 10. Graph CH1b shows the temporal change in the SNR of the received pulse signals SA of waves 1 to 10. That is, the combined reverberation Z0, which is a combination of surface reverberation Z1, underwater reverberation Z2, and volume reverberation Z3, is used as noise to calculate the SNR of multiple received pulse signals SA.

[0059] Figure 12 shows the time variation of the signal level at the receiving end at a distance L of 1000m. Graphs CH2a and CH2b correspond to graphs CH1a and CH1b in Figure 11.

[0060] Figure 13 shows the distance dependence of the levels and SNR of waves 1 through 10 (S10). Graph LV shows the distance dependence of the levels of waves 1 through 10 (S10). Graph SNR shows the distance dependence of the SNR of waves S1 through S10.

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

[0062] As described above, the communication range estimation device 110 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 an underwater environment. Based on a table representing the first relationship between the communication signal-to-noise ratio and the signal error rate, and the derived second relationship, the communication range in the underwater environment is estimated. As a result, by using the first and second relationships, efficient estimation of the communication range in an underwater environment becomes easy.

[0063] (modified version) The following describes a modified version of the communication range estimation device 110.

[0064] The information processing unit 111 may also provide the communication speed. The relationship between communication speed and bandwidth in a noisy communication channel is given 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] In other words, the information processing unit 111 calculates the SNR and, by applying this SNR and the bandwidth W determined by the device performance of the transmitting / receiving unit 122 to equation (1), the communication speed C can be calculated. Figure 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 the underwater environment based on the first relationship (relationship between SNR and BER) represented in table T1 (estimation process). The information processing unit 111 may estimate the communication speed instead of the communication range, or in addition to the communication range. Furthermore, this estimation of the communication speed may be performed in parallel with the estimation of the communication range.

[0067] For example, memory 112 can store a table representing the relationship between SNR and the communication speed C obtained from SNR, either in place of or together with table T1 representing the first relationship. By using this table, the information processing unit 11 can easily estimate the communication speed. As a result, the information processing unit 11 can calculate the communication speed according to, for example, the positional relationship between the transmitter and receiver (for example, 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 representing the maximum communication capacity (throughput) and is one indicator showing the relationship between SNR and communication speed C. The actual communication speed varies depending on the modulation method, coding rate, guard interval time, and communication method such as MIMO, for the same SNR. In other words, by calculating or measuring the SNR for various communication methods and creating a table showing the relationship between SNR and communication speed C, it becomes possible to calculate the communication speed more accurately.

[0069] Based on the communication speed C3: 16,000 [bps] and bandwidth W1: 8,000 [Hz] of 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] [Examples of implementation using software] 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 by software.

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

[0072] For processor C1, for example, a CPU (Central Processing Unit), GPU (Graphic Processing Unit), DSP (Digital Signal Processor), MPU (Micro Processing Unit), FPU (Floating Point Number Processing Unit), PPU (Physics Processing Unit), TPU (Tensor Processing Unit), quantum processor, microcontroller, or a combination thereof can be used. For memory C1, for example, flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof can be used.

[0073] Computer C may also be equipped with RAM (Random Access Memory) for loading program P at runtime and for temporarily storing various data. Furthermore, computer C may be equipped with communication interfaces for sending and receiving data with other devices. Additionally, computer C may be equipped with input / output interfaces for connecting input / output devices such as keyboards, mice, displays, and printers.

[0074] Furthermore, program P can be recorded on a non-temporary, tangible recording medium M that is readable by computer C. Such a recording medium M could be, for example, tape, disk, card, semiconductor memory, or programmable logic circuitry. Computer C can acquire program P via such a recording medium M. Program P can also be transmitted via a transmission medium. Such a transmission medium could be, for example, a communication network or broadcast waves. Computer C can also acquire program P via such a transmission medium.

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

[0076] [Additional Note 2] Some or all of the embodiments described above may also be described as follows. However, the present invention is not limited to the embodiments described below.

[0077] (Note 1) The communication range estimation device is used to estimate the communication range using sound wave signals in an underwater environment and comprises a memory that stores a table representing a first relationship between the communication signal-to-noise ratio and the signal error rate, and an information processing unit. The information processing unit performs a derivation process to derive a second relationship between the transmission-to-reception position relationship between the transmitting and receiving sides and the signal-to-noise ratio based on the communication environment conditions in the underwater environment, and an estimation process to estimate the 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, the communication range in an underwater environment can be efficiently estimated based on a table representing the first relationship between the communication signal-to-noise ratio and the signal error rate.

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

[0080] According to the above configuration, a second relationship between the transmission-reception positional relationship between the transmitting and receiving sides and the signal-to-noise ratio can be efficiently derived using pulse signals.

[0081] (Note 3) The received pulse signal in item 1 is selected based on the communication path by the communication range estimation device in item 2.

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

[0083] (Note 4) The received pulse signal in item 1 is selected based on the signal strength or waveform state of the communication range estimation device as described in Appendix 2.

[0084] With 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 condition.

[0085] (Note 5) The information processing unit is a communication range estimation device according to any of the appendices 1 to 4, which estimates the communication range in the underwater environment based on the allowable range of the 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 acceptable range of the communication signal-to-noise ratio.

[0087] (Note 6) The table above shows the modulation scheme of the communication and the communication Equalization A communication range estimation device, one of the devices specified in appendices 1 to 5, that represents the first relationship in multiple communication systems in which at least one of the methods differs.

[0088] The above configuration allows for efficient estimation of the communication range in an underwater environment for multiple communication methods.

[0089] (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 type.

[0090] According to the above configuration, the communication range in the underwater environment can be efficiently estimated based on wind speed, depth, water depth, and bottom sediment in the marine environment.

[0091] (Note 8) A method for estimating the communication range using sound wave signals in an underwater environment, comprising: a derivation process for deriving a second relationship between the positional relationship between a transmitter and a receiver and the signal-to-noise ratio based on the communication environment conditions in the underwater environment; a table representing a first relationship between the communication signal-to-noise ratio and the signal error rate; and an estimation process for estimating the communication range in the underwater environment based on the derived second relationship.

[0092] According to the above configuration, the communication range in an underwater environment can be efficiently estimated based on a table representing the first relationship between the communication signal-to-noise ratio and the signal error rate.

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

[0094] (Note 10) A communication range estimation system comprising: a communication device for transmitting and receiving sound wave signals through an underwater environment; and a communication range estimation device for estimating the communication range in the underwater environment, wherein the communication range estimation device includes a memory for storing a table representing a first relationship between the communication signal-to-noise ratio and the signal error rate, and an information processing unit, wherein the information processing unit performs a derivation process for deriving a second relationship between the positional relationship between the transmitting side and the receiving side and the signal-to-noise ratio, when the communication device is either the transmitting side or the receiving side of the sound wave signal, based on the communication environment conditions in the underwater environment; and an estimation process for estimating the 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 a table representing the first relationship between the communication signal-to-noise ratio and the signal error rate. Furthermore, by installing the communication device and the communication range estimation device on a small vessel or submersible, the communication range can be appropriately estimated according to the communication environment conditions in the underwater environment.

[0096] (Note 11) A communication range estimation device for estimating the communication range using sound wave signals in an underwater environment, comprising: a memory for storing a table representing a first relationship between the communication signal-to-noise ratio and the signal error rate; and at least one processor, wherein the processor performs a derivation process for deriving a second relationship between the inter-transmitter positional relationship between the transmitting and receiving sides and the signal-to-noise ratio based on the communication environment conditions in the underwater environment; and an estimation process for estimating the communication range in the underwater environment based on the first relationship represented in the table and the derived second relationship.

[0097] Furthermore, this communication range estimation system may also be equipped with memory for storing programs, and this memory may store programs that cause the processor to perform derivation and estimation processes. This program may also be recorded on a computer-readable, non-temporary, tangible recording medium. [Explanation of symbols]

[0098] 100 Communication Range Estimation System 10, 110 Communication range estimation device 11, 111 Information Processing Unit 12,112 memory 120130 Communication equipment 121, 131 Communication Control Unit 122, 132 Transmitter / Receiver S10, S100 Communication range estimation method T1 Table

Claims

1. A communication range estimation device used for estimating the communication range using sound wave signals in an underwater environment, A memory that stores a table representing the first relationship between the signal-to-noise ratio and the signal error rate, It comprises an information processing unit, The aforementioned information processing unit, Based on the communication environment conditions in the underwater environment, a derivation process is performed to derive a second relationship between the positional relationship between the transmitting and receiving sides and the signal-to-noise ratio, An estimation process for estimating the communication range in the underwater environment based on the first relationship shown in the table and the second relationship derived therefrom, A communication range estimation device that performs this operation.

2. The information processing unit, in the derivation process, The communication range estimation device according to claim 1, which derives the second relationship with respect to one of a plurality of received pulse signals that are received by the receiving side and have different required times from the transmitting side, corresponding to one transmitted pulse signal transmitted from the transmitting side.

3. The communication range estimation device according to claim 2, wherein the received pulse signal of 1 is selected based on the communication path.

4. The communication range estimation device according to claim 2, wherein the received pulse signal in 1 is selected based on signal strength or waveform state.

5. The information processing unit, in the estimation process, A communication range estimation device according to claim 1, which estimates the communication range in the underwater environment based on the allowable range of the 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 in a plurality of communication systems in which at least one of the communication modulation scheme and the communication equalization scheme is different.

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

8. A communication range estimation method used for estimating the communication range using sound wave signals in an underwater environment, Based on the communication environment conditions in the underwater environment, a derivation process is performed to derive a second relationship between the positional relationship between the transmitting and receiving sides and the signal-to-noise ratio, A table representing the first relationship between the signal-to-noise ratio and the signal error rate, and an estimation process for estimating the communication range in the underwater environment based on the derived second relationship, A method for estimating the communication range, including the above.

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

10. A communication device that transmits and receives sound wave signals through an underwater environment, The system includes a communication range estimation device for estimating the communication range in the aforementioned underwater environment, The communication range estimation device is A memory that stores a table representing the first relationship between the signal-to-noise ratio and the signal error rate, It comprises an information processing unit, The aforementioned information processing unit, Based on the communication environment conditions in the underwater environment, a derivation process is performed to derive a second relationship between the positional relationship between the transmitting and receiving sides and the signal-to-noise ratio, when the communication device is either the transmitting or receiving side of the sound wave signal. An estimation process for estimating the communication range in the underwater environment based on the first relationship shown in the table and the second relationship derived therefrom, A communication range estimation system that performs this task.

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