An environment-adaptive underwater acoustic communicator and communication method

Abstract

The present invention relates to an environment-adaptive underwater acoustic communication machine and a communication method, belonging to the technical field of underwater acoustic communication, and solves the problem that existing underwater acoustic communication machines fail to make full use of ocean environment parameters and cannot match the complex and changeable ocean environment. The method includes: obtaining ocean environment parameters and transmission parameters of the underwater acoustic communication machine at the transmitting end, as well as the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine; performing simulation of an underwater acoustic communication channel within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the ocean environment parameters and transmission parameters of the underwater acoustic communication machine at the transmitting end, and performing simulation of underwater acoustic communication performance according to the simulated underwater acoustic communication channel; calculating the underwater acoustic communication quality according to the underwater acoustic communication performance, and adjusting the transmission parameters of the underwater acoustic communication machine at the transmitting end according to the underwater acoustic communication quality.

Description

Technical Field

[0001] The present invention relates to the field of underwater acoustic communication technology, and in particular, to an environment-adaptive underwater acoustic communication machine and a communication method. Background Art

[0002] Underwater unmanned platforms have characteristics such as strong mobility, high autonomy, and strong environmental adaptability. They can carry different types of payloads according to mission requirements and are important nodes in the air-space-earth-sea cross-domain integrated network. With the development of ocean development and national defense construction, major demands for ocean information transmission have been put forward in fields such as ocean engineering development, ocean resource exploration, and ocean environment observation. It is necessary for underwater unmanned observation platforms to transmit underwater data to the water surface in real time or near real time, and then be relayed by surface relay nodes to shore-based or Internet data fusion centers. Affected by the absorption attenuation and scattering characteristics of seawater, the propagation attenuation of electromagnetic waves and light waves in water is very serious, resulting in a very limited propagation distance. However, the propagation attenuation of sound waves underwater is weak, and they can effectively propagate over long distances in water bodies. However, due to the slower speed of sound propagation in seawater than that of electromagnetic waves and the complex and variable topography of the sea surface and seabed, the underwater acoustic communication channel has three-dimensional complex variation characteristics in time-space-frequency, manifested as large multipath time delay, high environmental noise, limited spectral bandwidth, large spatial fluctuations, etc., which seriously restrict the reliability of the underwater acoustic communication link and the effectiveness of information transmission.

[0003] In traditional adaptive underwater acoustic communication methods, only the signal is processed at the receiving end, and the channel prediction result is sent back to the transmitting end, and the transmission parameters are adaptively adjusted according to the channel state information to optimize the system throughput, resulting in a large amount of delay overhead, making the channel state information outdated or estimated inaccurately, which is not conducive to real-time online adjustment of transmission parameters; at the same time, the research on the ocean environment is crucial for the development of underwater acoustic technology. The close combination of underwater acoustics physics, signal processing and the ocean environment is an inevitable trend in the development of underwater acoustic technology, and matching the ocean environment is the goal pursued by underwater acoustic signal processing.

[0004] Therefore, there is a lack of an environment-adaptive underwater acoustic communication machine and a communication method in the prior art that use ocean environment information to predict and estimate the state of the communication channel. Summary of the Invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide an environment-adaptive underwater acoustic communication machine and a communication method to solve the problem that the existing underwater acoustic communication machine fails to make full use of ocean environment parameters and cannot match the complex and variable ocean environment.

[0006] On the one hand, an embodiment of the present invention provides an environment-adaptive underwater acoustic communication method, including:

[0007] Obtain the marine environmental parameters, the transmission parameters of the transmitting - end underwater acoustic communication machine, as well as the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine;

[0008] Perform underwater acoustic communication channel simulation within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the marine environmental parameters and the transmission parameters of the transmitting - end underwater acoustic communication machine, and perform underwater acoustic communication performance simulation according to the simulated underwater acoustic communication channel;

[0009] Calculate the underwater acoustic communication quality according to the underwater acoustic communication performance, and adjust the transmission parameters of the transmitting - end underwater acoustic communication machine according to the underwater acoustic communication quality.

[0010] Further, performing underwater acoustic communication channel simulation within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the marine environmental parameters and the transmission parameters of the transmitting - end underwater acoustic communication machine includes:

[0011] Obtain the equiphase surface and acoustic wave amplitude of the acoustic wave transmission within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the marine environmental parameters and the transmission parameters of the transmitting - end underwater acoustic communication machine; wherein, the marine environmental parameters include: marine water temperature, salinity, depth, seabed topography, and marine environmental noise;

[0012] Obtain the eigen - ray cluster within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the equiphase surface, acoustic wave amplitude, and seabed topography;

[0013] Obtain the propagation amplitude and propagation time delay of each eigen - ray in the eigen - ray cluster;

[0014] Obtain the impulse response of the simulated underwater acoustic communication channel according to the propagation amplitude and propagation time delay of each eigen - ray.

[0015] Further, obtaining the equiphase surface and acoustic wave amplitude of the acoustic wave transmission within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the marine environmental parameters and the transmission parameters of the transmitting - end underwater acoustic communication machine is specifically:

[0016]

[0017] k = ω / c

[0018] c = 1449.2 + 4.6T e - 0.055T e 2 + 0.00029T e 3

[0019] +(1.34 - 0.01T e )(S - 35)+0.016z

[0020] Among them, is the Laplace operator, A is the acoustic ray amplitude function, P is the acoustic ray phase function, k is the wave number, ω is the angular frequency of the signal transmitted by the transmitting end, c is the speed of sound, and T e is the Celsius temperature of the ocean water body, S is the salinity of the ocean water body, and z is the seawater depth.

[0021] Furthermore, the impulse response h(t, r, z s , z d ) is expressed as:

[0022]

[0023] Among them, h(t, r, z s , z d ) is the channel impulse response in the cylindrical coordinate system (r, z). The cylindrical coordinate system takes the projection point of the center point of the underwater acoustic communication machine at the transmitting end on the sea level as the origin. L is the number of eigenrays, and A l (r, z s , z d ) is the propagation amplitude function of the l-th eigenray. τ l (r, z s , z d ) is the propagation delay function of the l-th eigenray passing through the underwater acoustic channel. δ(·) is the Dirac function. z s is the z component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, and z d is the z component of the receiving underwater acoustic communication machine in the cylindrical coordinate system. r is the horizontal communication distance between the transmitting underwater acoustic communication machine and the receiving underwater acoustic communication machine.

[0024] Furthermore, the simulation of the underwater acoustic communication performance based on the simulated underwater acoustic communication channel includes:

[0025] The transmitted information bit b(t) is encoded and modulated to generate the communication signal s(t) to be transmitted;

[0026] The communication signal s(t) to be transmitted propagates through the simulated underwater acoustic communication channel to obtain the received signal x(t);

[0027] The received signal x(t) is demodulated and decoded to obtain the received information bit b′(t);

[0028] According to the transmitted information bit b(t) and the received information bit b′(t), calculate the communication bit error rate P b .

[0029] Further, the received signal x(t) is obtained by convolving the transmitted communication signal s(t) with the impulse response function h(t,r,z s ,z d ) of the channel, and is expressed as:

[0030]

[0031]

[0032] where s(t) is the communication signal to be transmitted, b(t) is the transmitted information bit, f c =ω / 2π is the carrier frequency, ω is the angular frequency of the signal transmitted at the transmitter, is the initial phase, j is the imaginary unit, t is the transmission time, * is the convolution operation, w(t) is the ocean environmental noise, L is the number of eigenrays, A l (r,z s ,z d ) is the propagation amplitude function of the l-th eigenray, α is the Doppler factor, τ l (r,z s ,z d ) is the propagation delay function of the l-th eigenray passing through the underwater acoustic channel, z s is the z-component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, z d is the z-component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, and r is the horizontal communication distance between the transmitting and receiving underwater acoustic communication machines.

[0033] Further, calculating the underwater acoustic communication quality according to the underwater acoustic communication performance includes:

[0034] Obtaining the average bit error rate value of the transmitted communication data within the duration T according to the bit error rate P b under the current transmitter parameters and ocean environmental parameters, as well as the horizontal and vertical communication distances of the underwater acoustic communication machines.

[0035] Calculating the correct probability of receiving information in the underwater acoustic communication channel according to the average bit error rate value , and the correct probability of receiving information in the underwater acoustic communication channel is expressed as:

[0036]

[0037] where, is the average bit error rate value, is the probability that the position of the transmitting underwater acoustic communication machine is (0, Z s ) and the position of the receiving underwater acoustic communication machine is (R, Z d ) when the average bit error rate value is 0; P(r = R,zs =Z s , z d =Z d ) is the probability that the position of the transmitting underwater acoustic communicator is (0, Z s ) and the position of the receiving underwater acoustic communicator is (R, Z d ), z s is the z-component of the transmitting underwater acoustic communicator in the cylindrical coordinate system, z d is the z-component of the receiving underwater acoustic communicator in the cylindrical coordinate, and r is the horizontal communication distance between the transmitting underwater acoustic communicator and the receiving underwater acoustic communicator.

[0038] Furthermore, adjusting the transmitting end parameters of the underwater acoustic communicator according to the underwater acoustic communication quality includes:

[0039] Presetting the correct probability threshold P of the information received by the underwater acoustic communicator th ;

[0040] When the correct probability of the information received by the underwater acoustic communicator , reduce the modulation order, symbol rate, and error correction code rate of the data modulation module in the underwater acoustic communicator, and adjust the position of the underwater acoustic communicator to reduce the horizontal communication distance and vertical communication distance between the transmitting underwater acoustic communicator and the receiving underwater acoustic communicator until the correct probability of the information received by the underwater acoustic communicator

[0041] wherein, is the average bit error rate value under the current transmitting end parameters of the underwater acoustic communicator within the T time period, z s =Z s is the z-component of the transmitting underwater acoustic communicator in the cylindrical coordinate system, z d =Z d is the z-component of the receiving underwater acoustic communicator in the cylindrical coordinate, and r = R is the horizontal communication distance between the transmitting underwater acoustic communicator and the receiving underwater acoustic communicator.

[0042] Furthermore, adjusting the transmitting end parameters of the underwater acoustic communicator according to the underwater acoustic communication quality further includes:

[0043] Presetting the parameter adjustment period T of the underwater acoustic communicator m ;

[0044] When the correct probability of the information received by the underwater acoustic communicator , start timing, and after an interval of the parameter adjustment period T m , adjust the transmitting end parameters of the underwater acoustic communicator again according to the environment-adaptive underwater acoustic communication method;

[0045] wherein, P th is the correct probability threshold of the information received by the underwater acoustic communicator, is the average bit error rate value under the current transmission - end parameters of the underwater acoustic communicator within the T time period, z s = Z s is the z - component of the transmitting underwater acoustic communicator in the cylindrical coordinate system, z d = Z d is the z - component of the receiving underwater acoustic communicator in the cylindrical coordinate system, and r = R is the horizontal communication distance between the transmitting underwater acoustic communicator and the receiving underwater acoustic communicator.

[0046] On the other hand, the embodiment of the present invention provides an environment - adaptive underwater acoustic communicator, including:

[0047] A parameter acquisition module, configured to acquire ocean environment parameters, transmitting - end underwater acoustic communicator transmitting parameters, as well as the horizontal communication distance and vertical communication distance of the underwater acoustic communicator;

[0048] An underwater acoustic channel simulation module, configured to simulate the underwater acoustic communication channel within the horizontal communication distance and vertical communication distance of the underwater acoustic communicator according to the ocean environment parameters and transmitting - end underwater acoustic communicator transmitting parameters, and perform underwater acoustic communication performance simulation according to the simulated underwater acoustic communication channel;

[0049] A parameter adjustment module, configured to calculate the underwater acoustic communication quality according to the underwater acoustic communication performance, and adjust the transmitting parameters of the transmitting - end underwater acoustic communicator according to the underwater acoustic communication quality.

[0050] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0051] 1. The present invention combines the ocean environment parameters (such as seawater characteristics, seabed characteristics, sea - surface characteristics, sound speed, etc.) of the ocean where the underwater acoustic communicator is located with measurement data and acoustic models to perform underwater acoustic communication system performance simulation and prediction, and online adaptively adjust the modulation parameters of the transmitting end of the underwater acoustic communicator and the position and speed parameters of the carried platform to cope with the complex and changeable ocean environment;

[0052] 2. In the present invention, the transmitting end of the underwater acoustic communicator predicts the quality of the underwater acoustic communication link based on the dynamic information of the ocean environment, calculates the underwater acoustic communication quality, and online and real - time adaptively adjusts the underwater acoustic communication signal parameters according to the underwater acoustic communication quality to realize real - time online optimization of the system throughput;

[0053] 3. The present invention does not require the receiving end to feedback the channel state information to the transmitting end, reduces the delay overhead of the underwater acoustic communicator for adjusting the transmitting - end parameters, and improves the robustness and adaptive adjustment efficiency of the underwater acoustic communicator in the ocean environment.

[0054] In the present invention, the above technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the following specification, and some advantages can be made obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained from the content specifically pointed out in the specification and the drawings. Description of the Drawings

[0055] The drawings are only for the purpose of showing specific embodiments and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs denote the same components.

[0056] Figure 1 Flowchart of the environment adaptive underwater acoustic communication method shown in an embodiment of the present application;

[0057] Figure 2 Schematic diagram of the structural composition of the environment adaptive underwater acoustic communication machine shown in an embodiment of the present application;

[0058] Figure 3 Flowchart of the underwater acoustic communication channel simulation shown in an embodiment of the present application;

[0059] Figure 4 Schematic diagram of the eigenrays of the underwater acoustic communication channel shown in an embodiment of the present application;

[0060] Figure 5 Schematic diagram of the impulse response of the simulated underwater acoustic communication channel shown in an embodiment of the present application;

[0061] Figure 6 Schematic diagram of the connection of the environment adaptive underwater acoustic communication machine shown in another embodiment of the present application. Detailed Embodiments

[0062] The following will specifically describe the preferred embodiments of the present invention with reference to the drawings. The drawings form a part of the present application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0063] As Figure 1 shown, a specific embodiment of the present invention discloses an environment adaptive underwater acoustic communication method, and the underwater acoustic communication method includes:

[0064] S10. Obtain the ocean environment parameters, the transmission parameters of the underwater acoustic communication machine at the transmitting end, and the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine;

[0065] Specifically, there are mainly three sources for obtaining ocean environmental parameters: the first is from the historical observation data of the current sea area; the second is the ocean environmental data collected by the environmental parameter measurement sensors of the underwater acoustic communication machine itself; the third source is the ocean environmental data collected by the environmental parameter measurement sensors in another underwater acoustic communication machine that communicates with the underwater acoustic communication machine. More specifically, the environmental parameter measurement sensors mainly include, but are not limited to, temperature, salinity, and pressure measurement sensors, and acoustic Doppler current profilers, which are used to collect and measure the current ocean water temperature, salinity, sound pressure, seabed topography, and ocean environmental noise in real time.

[0066] Specifically, as Figure 2 shown, the underwater acoustic communication machine includes the surface underwater acoustic communication machine 12 installed on the surface ship 10 and the underwater acoustic communication machine 14 installed on the underwater unmanned platform 16. The surface underwater acoustic communication machine 12 and the underwater underwater acoustic communication machine 14 realize the data communication function between the surface ship and the underwater unmanned platform. The communication quality of the underwater acoustic communication channel of the underwater acoustic communication machine is related to the horizontal communication distance and vertical communication distance between the surface underwater acoustic communication machine and the underwater underwater acoustic communication machine, as well as the parameters of the transmitting and receiving ends of the underwater acoustic communication machine. Specifically, in the environment adaptive underwater acoustic communication method, the position information of the underwater underwater acoustic communication machine is obtained through the DVL or inertial navigation system in the underwater carrier platform, the position of the surface underwater acoustic communication machine is obtained through the position obtained by the GPS in the surface ship and the hanging distance of the surface communication machine, and the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine, as well as the transmitting end parameters of the underwater acoustic communication machine, are obtained through the position of the surface communication machine and the position of the underwater communication machine. The transmitting end parameters include: underwater acoustic communication signal modulation style, symbol rate, carrier frequency, bandwidth, error correction code type, and error correction code rate, etc.

[0067] More specifically, the communication module of the underwater acoustic communication machine includes a transmitting part and a receiving part. The transmitting part is provided with a signal symbol input interface, a synchronization signal generation module, a data modulation module, an error control coding module, a digital-to-analog converter, a power amplifier, a transmitting transducer, etc. The receiving part is provided with a receiving transducer, a preamplification module, an analog-to-digital converter, a synchronization module, a data demodulation module, a channel decoding module, etc. The data modulation module realizes different underwater acoustic communication modulation methods based on signal parameters (frequency, bandwidth, symbol rate, modulation method, channel coding, etc.).

[0068] S20. Perform underwater acoustic communication channel simulation within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the ocean environmental parameters and the transmitting parameters of the transmitting end underwater acoustic communication machine, and perform underwater acoustic communication performance simulation according to the simulated underwater acoustic communication channel.

[0069] Specifically, as Figure 3As shown, acoustic communication channel simulation within the horizontal and vertical communication distances of an acoustic communication machine is performed according to the marine environmental parameters and the transmission parameters of the transmitting - end acoustic communication machine, including:

[0070] S2011. Obtain the equi - phase surface and acoustic wave amplitude of acoustic wave transmission within the horizontal and vertical communication distances of the acoustic communication machine according to the marine environmental parameters and the transmission parameters of the transmitting - end acoustic communication machine;

[0071] Specifically, a physical model of the sound propagation process is established to describe the sound propagation characteristics in the ocean, which can be mathematically expressed as a process of solving the wave equation under specific boundary conditions and medium conditions; the wave equation in an ideal fluid is expressed as:

[0072]

[0073] where ρ is the density of the seawater medium, p is the sound pressure, one of the obtained marine environmental parameters, c is the sound speed in seawater calculated through temperature, salinity, and sound pressure, t is time, is the Laplace operator.

[0074] When the transmitting - end emits a continuous wave e with an angular frequency of ω jωt then the frequency - domain form of the wave equation - - the Helmholtz equation is obtained, which is expressed as:

[0075]

[0076] where k = ω / c = 2π / λ, c is the sound speed, k is the wave number, and λ is the wavelength.

[0077] More specifically, in this embodiment, the ray model is selected for acoustic communication channel simulation. Specifically, the solution of the Helmholtz equation in the ray model is:

[0078] φ = Ae iP

[0079] A = A(r,z)

[0080] P = P(r,z)

[0081] where A = A(r,z) and P = P(r,z) are the propagation amplitude function and phase function at a certain position in the cylindrical coordinate (r,z) system respectively;

[0082] Specifically, substituting φ = Ae iP into the above - mentioned wave equation according to the marine environmental parameters and the transmission parameters of the transmitting - end acoustic communication machine, the equi - phase surface and acoustic wave amplitude of acoustic wave transmission within the horizontal and vertical communication distances of the acoustic communication machine are obtained, specifically:

[0083]

[0084] k = ω / c

[0085] c = 1449.2 + 4.6T e - 0.055T e 2 + 0.00029T e 3

[0086] + (1.34 - 0.01T e )(S - 35) + 0.016z

[0087] wherein, is the Laplace operator, A is the ray amplitude function, P is the ray phase function, k is the wave number, ω is the angular frequency of the signal transmitted by the transmitting end, c is the sound speed, T e is the Celsius temperature of the ocean water body, S is the salinity of the ocean water body, and z is the sea water depth.

[0088] Specifically, the geometric shape of the ray can be determined according to the above formula (1); the above formula (2) is the transmission equation, and the amplitude of the sound wave is determined according to formula (2).

[0089] More specifically, assuming that the sound speed does not change within one wavelength, from the eikonal equation is obtained through formula (1):

[0090]

[0091] A set of planes with equal phases defined by the eikonal equation is an equiphase surface (i.e., wavefront), and each equiphase surface P corresponds to a unique constant.

[0092] Specifically, the ray model is selected for use in underwater acoustic communication channel simulation. When using the ray model for underwater acoustic communication channel simulation, the ray model has an absolute advantage in computational efficiency in high-frequency and complex environments. At the same time, the ray equation in the ray model is independent of the signal frequency. In broadband simulation, only the ray trajectory needs to be solved once, greatly simplifying the computational amount.

[0093] S2012. Obtain the cluster of eigenrays within the horizontal and vertical communication distances of the underwater acoustic communication machine according to the equiphase surface, the sound wave amplitude, and the seabed topography;

[0094] Specifically, in the ray model, the propagation of sound waves is regarded as the propagation of countless rays perpendicular to the equiphase surface, and the normal line of the wavefront is the sound ray; the eikonal expresses the length of the sound ray path as a function of the two endpoints of the path; according to formula (2) and the position information of the underwater acoustic communicator at the transmitting end and the underwater acoustic communicator at the receiving end, when the two endpoints of the sound ray are at the positions of the underwater acoustic communicator at the transmitting end and the underwater acoustic communicator at the receiving end, it is called the eigenray, which is the distance-depth (r, z) in the cylindrical coordinate system; as Figure 4 shown, according to the ocean water velocity, sea surface wind speed and seabed topography in the ocean environmental parameters, the emission point and the reception point in the ocean sound field are connected by the eigenray family, "○" is the transmitting end, and "□" is the receiving end, and the eigenray cluster is between the receiving end and the transmitting end.

[0095] S2013. Obtain the propagation amplitude and propagation time delay of each eigenray in the eigenray cluster;

[0096] Specifically, when using the ray model to solve the channel impulse response, it is necessary to calculate the propagation amplitude A(r,z s ,z d ) and the propagation time delay τ l (r,z s ,z d ) along the l-th eigenray;

[0097] S2014. Obtain the impulse response of the simulated underwater acoustic communication channel according to the propagation amplitude and propagation time delay of each eigenray.

[0098] The channel impulse response h(t,r,z s ,z d ) in the cylindrical coordinate system is expressed as:

[0099]

[0100] where h(t,r,z s ,z d ) is the channel impulse response in the cylindrical coordinate system (r, z), the cylindrical coordinate system takes the projection point of the center point of the underwater acoustic communicator at the transmitting end on the sea surface as the origin, L is the number of eigenrays, A l (r,z s ,z d ) is the propagation amplitude function of the l-th eigenray, τ l (r,z s ,z d ) is the propagation time delay function of the l-th eigenray passing through the underwater acoustic channel, δ(·) is the Dirac function, z s is the z component of the transmitting underwater acoustic communicator in the cylindrical coordinate system, z dTo receive the z-component of the underwater acoustic communicator in cylindrical coordinates, and r is the horizontal communication distance between the transmitting underwater acoustic communicator and the receiving underwater acoustic communicator.

[0101] Specifically, as Figure 5 shown, different horizontal communication distances R and vertical communication distances Z = |z d - z s | result in different channel impulse responses, including propagation delay and amplitude response.

[0102] Specifically, the underwater acoustic communication performance is simulated according to the simulated underwater acoustic communication channel. Based on the results such as the channel impulse response, propagation loss, ocean ambient noise, and Doppler factor of the underwater acoustic channel simulation, the reliability of the underwater acoustic communication link under the preset parameters of the underwater acoustic communicator is predicted; specifically, the underwater acoustic communication performance simulation includes:

[0103] S2021. The transmitted information bit b(t) is encoded and modulated to generate the communication signal s(t) to be transmitted.

[0104] The transmitted information bit After being encoded by the channel error correction code, the output codeword is The codeword sequence c d After interleaving, it is mapped through modulation methods such as FSK and PSK to obtain the transmission symbol Up-converted to the carrier frequency of f c , forming the communication signal sequence to be transmitted where N d is the number of symbols, R is the code rate of the error correction code, and 2 M is the modulation order.

[0105] S2022. The communication signal sequence s(t) to be transmitted passes through the simulated underwater acoustic communication channel to obtain the received signal sequence x(t) at the receiving end of the simulated underwater acoustic communication channel.

[0106] Specifically, the transmitted communication signal sequence s(t) is convolved with the channel impulse response function h(t, r, z s , z d ) obtained in S2014. At the same time, the influence of ocean ambient noise and Doppler frequency shift is considered in the calculation, which is expressed as:

[0107]

[0108]

[0109] where s(t) is the communication signal to be transmitted, b(t) is the transmitted information bit, and f c = ω / 2π is the carrier frequency, and ω is the transmission frequency at the transmitting end. is the initial phase, j is the imaginary unit, t is the transmission time, * is the convolution operation, w(t) is the ocean ambient noise, L is the number of eigenrays, A l (r,z s ,z d ) is the propagation amplitude function of the l-th eigenray, α is the Doppler factor, τ l (r,z s ,z d ) is the propagation delay function of the l-th eigenray passing through the underwater acoustic channel, z s is the z-component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, z d is the z-component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, r is the horizontal communication distance between the transmitting and receiving underwater acoustic communication machines.

[0110] Specifically, there is relative motion between the transmitting and receiving ends of the underwater acoustic communication machine, and Doppler estimation is performed by transmitting a specifically designed signal; in specific implementation, the specifically designed signal is s p (t) = [p(t) s′(t) p(t)], where the duration of the communication data signal s′(t) is T0, and probe signals (the probe signals are linear frequency modulation signals or bi-phase modulation signals) p(t) are added at its head and tail. The received signal r p (t) is obtained. The correlation operation is performed between the probe signal and the received signal. Based on the Doppler invariance and strong correlation of the probe signal p(t), correlation peaks will appear for the probe signal. The duration between the two peaks is the duration T0′ of the communication data signal in the received signal. The Doppler factor α = T0′ / T0 - 1 can be estimated by the change in the duration of the communication data signal in the received signal.

[0111] S2023. Demodulate and decode the received signal x(t) to generate the received information bit b′(t); specifically, perform Doppler compensation, channel estimation and equalization, signal demodulation, and error correction code decoding on the received data for underwater acoustic communication signal demodulation, and the receiving end demodulates to obtain the information bit b′(t).

[0112] S2024. Calculate the communication error rate P under the current transmitting end parameters and ocean environment parameters according to the transmitted information bit b(t) and the received information bit b′(t) b .

[0113] Specifically, compare b(t) with b′(t), and the communication error rate P under the current communication parameters and ocean environment can be statistically obtained b , and realize the simulation and prediction of the underwater acoustic communication performance.

[0114] S30. Calculate the underwater acoustic communication quality according to the underwater acoustic communication performance, and adjust the transmission parameters of the transmitting end underwater acoustic communication machine according to the underwater acoustic communication quality.

[0115] Specifically, calculating the underwater acoustic communication quality according to the underwater acoustic communication performance includes:

[0116] Based on the communication error rate P under the current transmitter parameters and ocean environment parameters b , and the horizontal and vertical communication distances of the underwater acoustic communication machine, obtain the average error rate value of the transmitted communication data within the duration T

[0117] Based on the average error rate value Calculate the correct reception probability of the information received by the underwater acoustic communication channel (i.e., the probability that the communication data is received without error). The correct reception probability of the underwater acoustic communication channel is expressed as:

[0118]

[0119] Wherein, is the average error rate value, is the probability that the position of the transmitting underwater acoustic communication machine is (0, Z s ) and the position of the receiving underwater acoustic communication machine is (R, Z d ) under the condition that the average error rate value is 0; P(r = R, z s = Z s , z d = Z d ) is the probability that the position of the transmitting underwater acoustic communication machine is (0, Z s ) and the position of the receiving underwater acoustic communication machine is (R, Z d ); z s is the z-component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, z d is the z-component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, and r is the horizontal communication distance between the transmitting and receiving underwater acoustic communication machines.

[0120] Specifically, adjusting the transmitter parameters of the underwater acoustic communication machine according to the underwater acoustic communication quality includes:

[0121] Preset the correct reception probability threshold P of the underwater acoustic communication machine th ; Optionally, the correct reception probability threshold P th = 0.75;

[0122] When the correct reception probability of the underwater acoustic communication machine When it indicates that the underwater acoustic communication quality is less than the threshold value, that is, the current link quality is poor, it is necessary to reduce the modulation order, symbol rate, and error correction code rate of the data modulation module in the underwater acoustic communication machine, and adjust the position of the underwater acoustic communication machine to reduce the horizontal communication distance and vertical communication distance between the transmitting underwater acoustic communication machine and the receiving underwater acoustic communication machine; specifically, since both the position of the underwater acoustic communication machine and the communication parameters of the underwater acoustic communication machine have made adaptive adjustments to the changes in the current ocean environment, the underwater acoustic communication method needs to return to step S10, continue to update the ocean environment data, and continue to execute S10 - S30 until the probability of correct reception of information by the underwater acoustic communication machine That is, when the probability of correct reception of information When it indicates that the current communication link quality is high, the modulation parameters of the communication machine remain unchanged; among them, is the average bit error rate value under the current transmitter parameters of the underwater acoustic communication machine within the T time period, z s = Z s is the z - component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, z d = Z d is the z - component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, and R is the communication distance of the underwater acoustic communication machine;

[0123] More specifically, the adjustment of the transmitter parameters of the underwater acoustic communication machine according to the underwater acoustic communication quality further includes:

[0124] Preset the parameter adjustment period T of the underwater acoustic communication machine m ; specifically, from the perspective of energy conservation, the sea conditions can be estimated based on current or historical ocean observation data. If the sea condition level is high and the scale of ocean environment change is large, the parameter adjustment period T of the underwater acoustic communication machine m is set shorter. Optionally, it can be preset to 2 hours; if the sea condition level is low and the scale of ocean environment change is small, the parameter adjustment period T of the underwater acoustic communication machine m is set longer. Optionally, it can be preset to 2 days;

[0125] When the probability of correct reception of information by the underwater acoustic communication machine When it is, start timing. After an interval of the parameter adjustment period T m , the transmitter parameters of the underwater acoustic communication machine are adjusted again according to the environment - adaptive underwater acoustic communication method.

[0126] Optionally, the content of adjustment includes but is not limited to parameters such as the modulation style of the underwater acoustic communication signal, symbol rate, carrier frequency, bandwidth, error correction code type, code rate, etc., as well as the communication distance and depth between the surface ship and the underwater unmanned platform;

[0127] Compared with the prior art, the environment-adaptive underwater acoustic communication method proposed by the present invention combines the marine environment parameters (such as seawater characteristics, seabed characteristics, sea surface characteristics, sound speed, etc.) and measurement data of the ocean where the underwater acoustic communication machine is located with an acoustic model to simulate and predict the performance of the underwater acoustic communication system, and online adaptively adjusts the modulation parameters of the transmitting end of the underwater acoustic communication machine and the position and speed parameters of the carried platform to cope with the complex and changeable marine environment; in the present invention, the transmitting end of the underwater acoustic communication machine predicts the quality of the underwater acoustic communication link based on the dynamic information of the marine environment, calculates the quality of the underwater acoustic communication, and online and real-time adaptively adjusts the underwater acoustic communication signal parameters according to the quality of the underwater acoustic communication to achieve real-time online optimization of the system throughput; at the same time, the present invention does not require the receiving end to feedback the channel state information to the transmitting end, reducing the delay overhead of the underwater acoustic communication machine for adjusting the parameters of the transmitting end and improving the robustness and adaptive adjustment efficiency of the underwater acoustic communication machine in the marine environment.

[0128] As Figure 6 shown, another specific embodiment of the present invention discloses an environment-adaptive underwater acoustic communication machine, including:

[0129] A parameter acquisition module 100, configured to acquire marine environment parameters, transmitting parameters of the underwater acoustic communication machine at the transmitting end, as well as the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine;

[0130] An underwater acoustic channel simulation module 200, configured to simulate the underwater acoustic communication channel within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the marine environment parameters and the transmitting parameters of the underwater acoustic communication machine at the transmitting end, and simulate the underwater acoustic communication performance according to the simulated underwater acoustic communication channel;

[0131] A parameter adjustment module 300, configured to calculate the quality of the underwater acoustic communication according to the underwater acoustic communication performance, and adjust the transmitting parameters of the underwater acoustic communication machine at the transmitting end according to the quality of the underwater acoustic communication.

[0132] For the specific implementation process of the system embodiment in the present invention, reference may be made to the above method embodiment, and details are not described herein again. Since the principle of this embodiment is the same as that of the above method embodiment, this system also has the corresponding technical effects of the above method embodiment.

[0133] Those skilled in the art can understand that all or part of the processes of implementing the above method embodiments can be completed by instructing relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. Among them, the computer-readable storage medium is a magnetic disk, an optical disk, a read-only memory or a random access memory, etc.

[0134] As described above, it is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An environment-adaptive underwater acoustic communication method, characterized in that The underwater acoustic communication method includes: Obtaining ocean environment parameters, transmitting parameters of the underwater acoustic communicator at the transmitting end, as well as the horizontal communication distance and vertical communication distance of the underwater acoustic communicator; Performing underwater acoustic communication channel simulation within the horizontal communication distance and vertical communication distance of the underwater acoustic communicator according to the ocean environment parameters and transmitting parameters of the underwater acoustic communicator at the transmitting end, and performing underwater acoustic communication performance simulation according to the simulated underwater acoustic communication channel; Calculating the underwater acoustic communication quality according to the underwater acoustic communication performance, and adjusting the transmitting parameters of the underwater acoustic communicator at the transmitting end according to the underwater acoustic communication quality; Performing underwater acoustic communication channel simulation within the horizontal communication distance and vertical communication distance of the underwater acoustic communicator according to the ocean environment parameters and transmitting parameters of the underwater acoustic communicator at the transmitting end, including: Obtaining the equal-phase surface and acoustic wave amplitude of acoustic wave transmission within the horizontal communication distance and vertical communication distance of the underwater acoustic communicator according to the ocean environment parameters and transmitting parameters of the underwater acoustic communicator at the transmitting end; wherein, the ocean environment parameters include: ocean water temperature, salinity, depth, seabed topography, and ocean ambient noise; Obtaining the eigen-ray cluster within the horizontal communication distance and vertical communication distance of the underwater acoustic communicator according to the equal-phase surface, acoustic wave amplitude, and seabed topography; Obtaining the propagation amplitude and propagation delay of each eigen-ray from the eigen-ray cluster; Obtaining the impulse response of the simulated underwater acoustic communication channel according to the propagation amplitude and propagation delay of each eigen-ray; The impulse response , is expressed as: ； in, Cylindrical coordinate system The channel impulse response under the condition of , the cylindrical coordinate system takes the projection point of the center point of the transmitting end underwater acoustic communication device on the sea level as the origin, L is the number of eigenvalues, is the propagation amplitude function of the lth eigenvalue sound ray, is the propagation delay function of the lth eigenvalue line through the underwater acoustic channel, is the Dirac function, is the z component of the transmitting underwater acoustic communication device in the cylindrical coordinate system, is the z component of the receiving underwater acoustic communication device in cylindrical coordinates, is the horizontal communication distance between the transmitting and receiving underwater acoustic communication devices, For the transmission time.

2. The environment-adaptive underwater acoustic communication method according to claim 1, wherein The obtaining the equal-phase surface and acoustic wave amplitude of acoustic wave transmission within the horizontal communication distance and vertical communication distance of the underwater acoustic communicator according to the ocean environment parameters and transmitting parameters of the underwater acoustic communicator at the transmitting end is specifically: ； ； ； Among them, is the Laplace operator, is the ray amplitude function, is the ray phase function, is the wave number, is the angular frequency of the signal transmitted by the transmitter, is the speed of sound, is the ocean water temperature in Celsius, is the ocean water salinity, is the sea depth.

3. The environment-adaptive underwater acoustic communication method according to claim 1, wherein The performing underwater acoustic communication performance simulation according to the simulated underwater acoustic communication channel includes: Transmit information bits , and generate a communication signal to be transmitted after encoding and modulation ; Communication signal to be transmitted Propagate through the simulated underwater acoustic communication channel to obtain the received signal ; The received signal , after demodulation and decoding, the received information bits are obtained ; According to the transmitted information bits and the received information bits , calculate the communication bit error rate under the current transmitter parameters and ocean environment parameters .

4. The environment-adaptive underwater acoustic communication method according to claim 3, wherein The received signal , is obtained by convolving the transmitted communication signal with the impulse response function of the channel and is expressed as: ； ； Among them, is the communication signal to be transmitted, is the transmitted information bit, is the carrier frequency, is the angular frequency of the signal transmitted by the transmitter, is the initial phase, is the imaginary number, is the transmission time, is the convolution operation, is the ocean ambient noise, and L is the number of eigenrays, is the propagation amplitude function of the l-th eigenray, is the Doppler factor, is the propagation delay function of the l-th eigenray passing through the underwater acoustic channel, is the z-component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, is the z-component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, is the horizontal communication distance between the transmitting underwater acoustic communication machine and the receiving underwater acoustic communication machine.

5. The environment-adaptive underwater acoustic communication method according to claim 3, wherein The calculating the underwater acoustic communication quality according to the underwater acoustic communication performance includes: According to the communication bit error rate under the current transmitter parameters and ocean environment parameters , and the horizontal and vertical communication distances of the underwater acoustic communicator, obtain the average bit error rate value of the transmitted communication data within the duration T ; According to the average bit error rate value Calculate the correct probability of the received information of the underwater acoustic communication channel, and the correct probability of the received information of the underwater acoustic communication channel is expressed as: ； Among them, is the average bit error rate value, is the probability that the position of the transmitting underwater acoustic communication machine is and the position of the receiving underwater acoustic communication machine is under the condition that the average bit error rate value is 0; is the probability that the position of the transmitting underwater acoustic communication machine is and the position of the receiving underwater acoustic communication machine is ; is the z - component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, is the z - component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, =R is the horizontal communication distance between the transmitting underwater acoustic communication machine and the receiving underwater acoustic communication machine.

6. The environment-adaptive underwater acoustic communication method according to claim 5, wherein The adjusting the transmitting parameters of the underwater acoustic communicator at the transmitting end according to the underwater acoustic communication quality includes: Preset correct probability threshold for the received information of the underwater acoustic communicator ; When the correct probability of the underwater acoustic communication machine receiving information is reached, reduce the modulation order, symbol rate, and error correction code rate of the data modulation module in the underwater acoustic communication machine, and adjust the position of the underwater acoustic communication machine to reduce the horizontal communication distance and vertical communication distance between the transmitting underwater acoustic communication machine and the receiving underwater acoustic communication machine until the correct probability of the underwater acoustic communication machine receiving information ; Among them, is the average bit error rate value under the current transmitter parameters of the underwater acoustic communication machine during the T time period, is the z component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, is the z component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, is the horizontal communication distance between the transmitting underwater acoustic communication machine and the receiving underwater acoustic communication machine.

7. The environment-adaptive underwater acoustic communication method according to claim 6, wherein The adjusting the transmitting parameters of the underwater acoustic communicator at the transmitting end according to the underwater acoustic communication quality further includes: Preset parameter adjustment period of underwater acoustic communicator ; When the correct probability of the underwater acoustic communication machine receiving information starts timing, after an interval parameter adjustment period has passed, the parameters of the transmitting end of the underwater acoustic communication machine are adjusted again according to the environment-adaptive underwater acoustic communication method described above; wherein, is the correct probability threshold for the underwater acoustic communication machine to receive information, is the average bit error rate value under the current transmitter parameters of the underwater acoustic communication machine within the T time period, is the z component of the transmitting underwater acoustic communication machine in the cylindrical coordinate system, is the z component of the receiving underwater acoustic communication machine in the cylindrical coordinate system, is the horizontal communication distance between the transmitting underwater acoustic communication machine and the receiving underwater acoustic communication machine.

8. An environment-adaptive underwater acoustic communicator, characterized in that, The underwater acoustic communicator includes: A parameter acquisition module, configured to acquire ocean environment parameters, transmitting parameters of the underwater acoustic communicator at the transmitting end, as well as the horizontal communication distance and vertical communication distance of the underwater acoustic communicator; An underwater acoustic channel simulation module, configured to perform underwater acoustic communication channel simulation within the horizontal communication distance and vertical communication distance of the underwater acoustic communicator according to the ocean environment parameters and transmitting parameters of the underwater acoustic communicator at the transmitting end, and perform underwater acoustic communication performance simulation according to the simulated underwater acoustic communication channel; A parameter adjustment module, which is used to calculate the underwater acoustic communication quality according to the underwater acoustic communication performance and adjust the transmission parameters of the underwater acoustic communication machine at the transmitting end according to the underwater acoustic communication quality; Performing underwater acoustic communication channel simulation within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the marine environmental parameters and the transmission parameters of the underwater acoustic communication machine at the transmitting end, including: Obtaining the equiphase surface and acoustic wave amplitude of acoustic wave transmission within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the marine environmental parameters and the transmission parameters of the underwater acoustic communication machine at the transmitting end; wherein, the marine environmental parameters include: ocean water temperature, salinity, depth, seabed topography and ocean environmental noise; Obtaining the eigen-ray cluster within the horizontal communication distance and vertical communication distance of the underwater acoustic communication machine according to the equiphase surface, acoustic wave amplitude and seabed topography; Obtaining the propagation amplitude and propagation time delay of each eigen-ray in the eigen-ray cluster; Obtaining the impulse response of the simulated underwater acoustic communication channel according to the propagation amplitude and propagation time delay of each eigen-ray; The impulse response , is expressed as: ； in, Cylindrical coordinate system The channel impulse response under the condition of , the cylindrical coordinate system takes the projection point of the center point of the transmitting end underwater acoustic communication device on the sea level as the origin, L is the number of eigenvalues, is the propagation amplitude function of the lth eigenvalue sound ray, is the propagation delay function of the lth eigenvalue line through the underwater acoustic channel, is the Dirac function, is the z component of the transmitting underwater acoustic communication device in the cylindrical coordinate system, is the z component of the receiving underwater acoustic communication device in cylindrical coordinates, is the horizontal communication distance between the transmitting and receiving underwater acoustic communication devices, For the transmission time.

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