Tight coupling underwater sound multi-user positioning and communication method

Abstract

The invention discloses a tight coupling underwater sound multi-user positioning and communication method. The method comprises the following steps that: a transmitting end generates a transmitting signal of a user by adopting a time domain superposition mode of a spread spectrum multi-user OFDM (Orthogonal Frequency Division Multiplexing) waveform and a multi-user positioning waveform; a transmitting signal reaches a receiving end through a channel, a receiving signal is respectively sent to two parallel signal processing branches, and the two signal processing branches respectively carry out multi-user spread spectrum OFDM communication demodulation and multi-user positioning calculation to realize underwater sound multi-user positioning and communication. According to the invention, the same signal can be adopted to realize multi-user positioning and communication functions at the same time, the efficiency problem of multi-user communication and positioning in an underwater operation scene is solved, and the underwater sound multi-user communication and positioning efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the field of underwater acoustic communication, relates to underwater acoustic multi-user positioning and communication, and specifically relates to a tightly coupled underwater acoustic multi-user positioning and communication method. Background Art

[0002] The 21st century is the century of the ocean. Human beings are facing great challenges in the development and protection of the ocean. Hydroacoustic communication and hydroacoustic positioning equipment are indispensable tools for the development and protection of the ocean. Traditional underwater data transmission and positioning are realized by two independent sets of equipment. This method not only increases the cost, but also increases the equipment operation and maintenance costs. In order to solve the communication and positioning problems with one set of equipment, researchers proposed to use time division multiplexing to realize communication and positioning functions. This method actually adds communication functions on the basis of the hardware of the positioning system. It is a loose coupling method of communication and positioning functions. The so-called loose coupling method refers to the communication and positioning of hydroacoustic communication and positioning functions through the same set of hardware equipment in a time-sharing manner, that is, the dedicated signal of hydroacoustic communication is used in the hydroacoustic communication period, and the dedicated signal of positioning is used in the positioning period. Since the loose coupling method cannot realize the communication and positioning functions at the same time through the same signal, the positioning and communication efficiency is not high. Summary of the invention

[0003] Purpose of the invention: In order to solve the communication and positioning efficiency problems of multiple users in underwater operation scenarios, a tightly coupled underwater acoustic multi-user positioning and communication method is provided, which adopts a tightly coupled manner to realize communication and positioning, and can realize communication and positioning functions simultaneously through the same signal, effectively improving the positioning and communication efficiency.

[0004] Technical solution: To achieve the above purpose, the present invention provides a tightly coupled underwater acoustic multi-user positioning and communication method, comprising the following steps:

[0005] S1: The transmitter generates the user's transmission signal by using the time domain superposition of the spread spectrum multi-user OFDM waveform and the multi-user positioning waveform;

[0006] S2: The transmitted signal reaches the receiving end through the channel, and the received signal is sent to two parallel signal processing branches respectively. The two signal processing branches perform multi-user spread spectrum OFDM communication demodulation and multi-user positioning solution respectively, realizing underwater acoustic multi-user positioning and communication.

[0007] Furthermore, the step S1 specifically includes:

[0008] A1: data a of the mth user to be transmitted m By mapping the symbols into the corresponding symbols x d,m , then perform multi-user spread spectrum operation to obtain the symbol x after spread spectrums,m , and then perform inverse Fourier transform to obtain the time domain multi-user spread spectrum OFDM signal to be transmitted x C,m ;

[0009] A2: Use a multi-user coding sequence as the waveform for multi-user positioning. The multi-user waveform can be an orthogonal sequence, such as a Gold sequence or a preferred PN sequence, to ultimately form a multi-user positioning sequence waveform x D,m ;

[0010] A3: Spread spectrum OFDM signal x for multiple users in the time domain C,m and multi-user positioning sequence waveform x D,m By superposition, the transmission signal x of the mth user can be generated T,m ,Right now

[0011] x T,m =x C,m +x D,m .

[0012] Furthermore, the time domain representation in step A3 is as follows:

[0013]

[0014] Among them, a k,m is the coded data of the mth user modulated on the kth subcarrier, f k =f 0 +kΔf, k=0,1,…,K-1,T g is the guard interval, and T is the OFDM symbol length.

[0015] Furthermore, the method for multi-user spread spectrum OFDM communication demodulation in step S2 includes:

[0016] B1: The first signal processing branch demodulates the data of the mth user, and the received signal is represented by y T,m ,Right now

[0017] y T,m =H S x S +w

[0018]

[0019] Among them, x S is the time domain signal of spread spectrum OFDM, w has a mean of 0 and a variance of Additive white Gaussian noise.

[0020] B2: Perform signal synchronization and Doppler estimation based on superimposed pilot to obtain the mth user transmitted data a m Estimates

[0021] Furthermore, the step B2 specifically includes:

[0022] C1: Using the synchronization and Doppler estimation technology of multi-branch autocorrelation, the baseband signal of the mth user positioning signal is expressed as

[0023]

[0024] Among them, T s is the symbol interval, x m (i) is the transmission waveform of the mth user, after the carrier is f c After modulation, the transmit passband signal is expressed as

[0025] s t (t) = Re{b(t)exp(j2πf c t)}

[0026] Where Re{·} represents the real part operation;

[0027] The received passband signal is expressed as

[0028] s r (t) = s t (t-τ(t))+w(t)

[0029] Where w(t) represents noise, τ(t) is the time-varying delay introduced by Doppler, that is,

[0030]

[0031] Where c is the speed of sound in water, τ 0 is the time-invariant propagation delay;

[0032] The received signal is used to perform autocorrelation calculation to obtain an estimate of the unknown velocity v and acceleration a; the Doppler frequency shift is estimated, and the received signal y is converted using linear interpolation or sampling rate conversion technology based on the estimated Doppler frequency shift. T,m Doppler compensation is performed to obtain the received signal y m,d ;

[0033] C2: for signal y m,d Perform FFT-based OFDM signal demodulation to obtain y FD,m ;

[0034] C3: for signal y FD,m Deinterleave to obtain the signal y to be despread DI,m ;

[0035] C4: Perform despreading operation, that is,

[0036]

[0037] Among them, c m is the spreading sequence of the mth user, The emission symbol x d,m estimates;

[0038] C5: Perform symbol demapping to obtain the transmission information a m Estimates

[0039] Furthermore, performing multi-user positioning solution based on the superposition sequence in step S2 specifically includes:

[0040] D1: For the positioning of the mth user, based on the ultra-short baseline positioning equation, the synchronization, Doppler estimation and compensation of the m users are first performed;

[0041] D2: Estimate the delay value of the mth user based on the copy correlation technology, and then obtain the relative delay value of the mth user relative to the ultra-short baseline positioning array, that is, perform a copy correlation operation on the signal received by the nth receiving element of the ultra-short baseline

[0042]

[0043] in, is the matched filter of the mth user, which can be directly constructed from the transmission waveform of the mth user; performing the same copy-related operation on other receiving primitives can obtain the relative delay value of the mth user relative to the five receiving primitives, that is, τ m,1 , τ m,2 , τ m,3 , τ m,4 , τ m,5 ;

[0044] D3: Based on the ultra-short baseline positioning principle, the mth user is located and the positioning position is obtained.

[0045] Further, the step D3 comprises:

[0046] E1: Calculate the slope distance R;

[0047] E2: calculate and obtain the user's position information;

[0048] E3: According to the slant distance R and the user's orientation information, the user's position in the rectangular coordinate system is obtained.

[0049] Further, the step E1 is specifically as follows: the position of the mth user in the base array reference coordinate system, the distance from the user to the origin of the coordinate system is R, the angles between the target and the x-axis, y-axis, and z-axis are α, β, and γ, then the coordinates of the target in the coordinate system are expressed as X=R·(cosα, cosβ, cosγ) T ,in(·) T represents the transpose of the matrix; the slant range R is obtained by the round-trip propagation delay of the reply mode, that is,

[0050]

[0051] Where c is the speed of sound, T tr is the round trip time of the signal.

[0052] Furthermore, the step E2 is specifically as follows: the ultra-short baseline positioning solution formula is uniformly written in the form of the following matrix, namely:

[0053] A+B=C·u

[0054] in

[0055]

[0056] u=(cosα,cosβ)

[0057] Among them, N 1 and N 2 Indicates array element 1 and array element 2, N 1 and N 3 Indicates array element 1 and array element 3; It means N 1 and N 2 represents the delay difference between array element 1 and array element 2, It means N 1 and N 2 represents the delay difference between array element 1 and array element 3; specifically for the positioning of the mth user, the delay τ m,1 , τ m,2 , τ m,3 , τ m,4 , τ m,5 The difference between the two is and Or other delay difference combinations; when the matrix C is full rank, the user position vector u is obtained, that is,

[0058] u=C -1 (A+B)

[0059] When the number of baselines involved in solving the target position information is greater than two, an overdetermined set of positioning equations is constructed. When the matrix C is full rank, the target position information is solved using the least squares principle.

[0060] u=(C T C) -1 C T (A+B)

[0061] The angle γ is obtained by using the following equation:

[0062] cos 2 α+cos 2 β+cos 2 γ=1.

[0063] Furthermore, the position of the user in the rectangular coordinate system in step E3 is:

[0064] X=R·(cosα,cosβ,cosγ) T .

[0065] Beneficial effect: Compared with the prior art, the present invention provides an underwater acoustic multi-user positioning and communication method using a tightly coupled method, which can use the same signal to simultaneously realize multi-user positioning and communication functions, breaking through the technical bottleneck that the existing loosely coupled method cannot use the same signal to simultaneously realize multi-user positioning and communication functions, thereby solving the problem of the efficiency of multi-user communication and positioning in underwater operation scenarios, and improving the efficiency of underwater acoustic multi-user communication and positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a schematic diagram of the process of the present invention;

[0067] Figure 2 Generate a flow chart for the waveform in detail;

[0068] Figure 3 It is a demodulation flow chart of multi-user communication information of the present invention;

[0069] Figure 4 It is a multi-user positioning flow chart of the present invention;

[0070] Figure 5 A schematic diagram of a multi-user positioning array array used in the present invention;

[0071] Figure 6 A schematic diagram of a multi-user positioning reference coordinate system used in the present invention;

[0072] Figure 7 This is the simulation result diagram of the bit error rate curve of user spread spectrum OFDM underwater acoustic communication. DETAILED DESCRIPTION

[0073] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0074] like Figure 1 As shown, the present invention provides a tightly coupled underwater acoustic multi-user positioning and communication method, comprising the following steps:

[0075] S1: The transmitter generates the user's transmission signal by using the time domain superposition of the spread spectrum multi-user OFDM waveform and the multi-user positioning waveform;

[0076] Step S1 specifically includes:

[0077] A1: Figure 2 As shown, the data a of the mth user to be transmitted m By mapping the symbols into the corresponding symbols x d,m , then perform multi-user spread spectrum operation to obtain the symbol x after spread spectrum s,m , and then perform inverse Fourier transform to obtain the time domain multi-user spread spectrum OFDM signal to be transmitted x C,m ;

[0078] A2: Use a multi-user coding sequence as the waveform for multi-user positioning. The multi-user waveform can be an orthogonal sequence, such as a Gold sequence or a preferred PN sequence, to ultimately form a multi-user positioning sequence waveform x D,m ;

[0079] A3: Spread spectrum OFDM signal x for multiple users in the time domain C,m and multi-user positioning sequence waveform x D,m By superposition, the transmission signal x of the mth user can be generated T,m ,Right now

[0080] x T,m =x C,m +x D,m

[0081] The time domain representation is as follows:

[0082]

[0083] Among them, a k,m is the coded data of the mth user modulated on the kth subcarrier, f k =f 0 +kΔf, k=0,1,…,K-1,T g is the guard interval, and T is the OFDM symbol length.

[0084] S2: The transmitted signal reaches the receiving end through the channel, and the received signal is sent to two parallel signal processing branches respectively. The two signal processing branches respectively perform multi-user spread spectrum OFDM communication demodulation and multi-user positioning solution to achieve underwater acoustic multi-user positioning and communication;

[0085] The transmitted signal reaches the receiving end after passing through the channel, and the received signal y 1 ,y 2 , …, y 5 The signals are sent to two parallel signal processing branches, one for demodulating multi-user communication information and the other for positioning multi-users, thus achieving communication and positioning with the same received signal.

[0086] like Figure 3 As shown, the method for multi-user spread spectrum OFDM communication demodulation includes:

[0087] B1: The first signal processing branch demodulates the data of the mth user, and the received signal is represented by y T,m ,Right now

[0088] y T,m =H S x S +w

[0089]

[0090] Among them, x S is the time domain signal of spread spectrum OFDM, w has a mean of 0 and a variance of Additive white Gaussian noise.

[0091] B2: Perform signal synchronization and Doppler estimation based on superimposed pilot to obtain the mth user transmitted data a m Estimates

[0092] Step B2 specifically includes:

[0093] C1: Using the synchronization and Doppler estimation technology of multi-branch autocorrelation, the baseband signal of the mth user positioning signal is expressed as

[0094]

[0095] Among them, T s is the symbol interval, x m (i) is the transmission waveform of the mth user, after the carrier is f c After modulation, the transmit passband signal is expressed as

[0096] s t (t) = Re{b(t)exp(j2πf c t)}

[0097] Where Re{·} represents the real part operation;

[0098] The received passband signal is expressed as

[0099] s r (t) = s t (t-τ(t))+w(t)

[0100] Where w(t) represents noise, τ(t) is the time-varying delay introduced by Doppler, that is,

[0101]

[0102] Where c is the speed of sound in water, τ 0 is the time-invariant propagation delay;

[0103] The received signal is used to perform autocorrelation calculation to obtain an estimate of the unknown velocity v and acceleration a; the Doppler frequency shift is estimated, and the received signal y is converted using linear interpolation or sampling rate conversion technology based on the estimated Doppler frequency shift. T,m Doppler compensation is performed to obtain the received signal y m,d ;

[0104] C2: for signal y m,d Perform FFT-based OFDM signal demodulation to obtain y FD,m ;

[0105] C3: for signal y FD,m Deinterleave to obtain the signal y to be despread DI,m ;

[0106] C4: Perform despreading operation, that is,

[0107]

[0108] Among them, c m is the spreading sequence of the mth user, The emission symbol x d,m estimates;

[0109] C5: Perform symbol demapping to obtain the transmission information a m Estimates

[0110] like Figure 4 As shown, multi-user positioning solution is performed based on the superposition sequence, specifically including:

[0111] D1: For the positioning of the mth user, based on the ultra-short baseline positioning equation, the synchronization, Doppler estimation and compensation of the m users are first performed;

[0112] D2: Based on the copy correlation technology, the delay value of the mth user can be estimated, and then the relative delay value of the mth user relative to the ultra-short baseline positioning array can be obtained, that is, the copy correlation operation is performed on the signal received by the nth receiving element of the ultra-short baseline.

[0113]

[0114] in, is the matched filter of the mth user, which can be directly constructed from the transmission waveform of the mth user; performing the same copy-related operation on other receiving primitives can obtain the relative delay value of the mth user relative to the five receiving primitives, that is, τ m,1 , τ m,2 , τ m,3 , τ m,4 , τ m,5 ;

[0115] D3: Based on the ultra-short baseline positioning principle, the mth user is located and the positioning position is obtained.

[0116] Step D3 includes:

[0117] E1: Calculate the slope distance R:

[0118] like Figure 6 As shown in the figure, the position of the mth user in the reference coordinate system of the base array, the distance from the user to the origin of the coordinate system is R, the angles between the target and the x-axis, y-axis, and z-axis are α, β, and γ, then the coordinates of the target in this coordinate system are expressed as X = R (cosα, cosβ, cosγ) T ,in(·) T represents the transpose of the matrix; the slant range R is obtained by the round-trip propagation delay of the reply mode, that is,

[0119]

[0120] Where c is the speed of sound, T tr is the round trip time of the signal.

[0121] E2: Calculate the user's position information:

[0122] The present invention adopts Figure 5 In the five-element array shown, the five elements are evenly distributed at the five vertices of an equilateral pentagon, with the z-axis perpendicular to the xoy plane and pointing upward. Based on the spherical coordinate system, the position of the element n in the coordinate system can be expressed as

[0123] The ultra-short baseline positioning solution formula is unified into the following matrix form:

[0124] A+B=C·u

[0125] in

[0126]

[0127] u=(cosα,cosβ)

[0128] Among them, N 1 and N 2 Indicates array element 1 and array element 2, N 1 and N 3 Indicates array element 1 and array element 3; It means N 1 and N 2 represents the delay difference between array element 1 and array element 2, It means N 1 and N 2 represents the delay difference between array element 1 and array element 3; specifically for the positioning of the mth user, the delay τ m,1 , τ m,2 , τ m,3 , τ m,4 , τ m,5 The difference between the two is and Or other delay difference combinations; when the matrix C is full rank, the user position vector u is obtained, that is,

[0129] u=C -1 (A+B)

[0130] When the number of baselines involved in solving the target position information is greater than two, an overdetermined set of positioning equations is constructed. When the matrix C is full rank, the target position information is solved using the least squares principle.

[0131] u=(C T C) -1 C T (A+B)

[0132] The angle γ is obtained by using the following equation:

[0133] cos 2 α+cos 2 β+cos 2 γ=1.

[0134] E3: Based on the slant distance R and the user's orientation information, the user's position in the rectangular coordinate system is obtained:

[0135] X=R·(cosα,cosβ,cosγ) T .

[0136] In order to verify the effectiveness and effect of the method of the present invention, assuming that communication and positioning adopt a 50% to 50% time slot allocation, the efficiency of the tight coupling method provided by the present invention is twice the efficiency of the loose coupling method. In the loose coupling method, the signal of the first 1 second is used for communication, and the signal of the second second is used for positioning; while in the tight coupling method, the signal of 1 second can realize both positioning and communication functions; the efficiency is doubled.

[0137] Based on the above content, this embodiment performs simulation tests and obtains the following Figure 7 The simulation results of the user spread spectrum OFDM underwater acoustic communication bit error rate curve are shown, where the spreading factor is 8, QPSK symbol mapping, the number of OFDM subcarriers is 1024, the communication frequency band is 7-13kHz, 4 users, and the preferred M sequence is used. Figure 7 The data can verify the effectiveness of the present invention.

Claims

1. A tightly coupled underwater acoustic multi-user positioning and communication method, characterized in that: The steps include: S1: The transmitter generates the user's transmission signal by using the time domain superposition of the spread spectrum multi-user OFDM waveform and the multi-user positioning waveform; S2: The transmitted signal reaches the receiving end through the channel, and the received signal is sent to two parallel signal processing branches respectively. The two signal processing branches perform multi-user spread spectrum OFDM communication demodulation and multi-user positioning solution respectively, realizing underwater acoustic multi-user positioning and communication.

2. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 1, characterized in that: The step S1 specifically includes: A1: data a of the mth user to be transmitted m By mapping the symbols into the corresponding symbols x d,m , then perform multi-user spread spectrum operation to obtain the symbol x after spread spectrum s,m , and then perform inverse Fourier transform to obtain the time domain multi-user spread spectrum OFDM signal to be transmitted x C,m ; A2: Use the multi-user coding sequence as the waveform for multi-user positioning, and finally form the multi-user positioning sequence waveform x D,m ; A3: Spread spectrum OFDM signal x for multiple users in the time domain C,m and multi-user positioning sequence waveform x D,m By superposition, the transmission signal x of the mth user can be generated T,m ,Right now x T,m =x C,m +x D,m 。 3. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 2, characterized in that: The time domain representation in step A3 is as follows: Among them, a k,m is the coded data of the mth user modulated on the kth subcarrier, f k =f0+kΔf,k=0,1,…,K-1,T g is the guard interval, and T is the OFDM symbol length.

4. The tightly coupled underwater acoustic multi-user positioning and communication method according to claim 1, characterized in that: The method for multi-user spread spectrum OFDM communication demodulation in step S2 includes: B1: The first signal processing branch demodulates the data of the mth user, and the received signal is represented by y T,m ,Right now y T,m =H S x S +w Among them, x S is the time domain signal of spread spectrum OFDM, w has a mean of 0 and a variance of Additive Gaussian white noise; B2: Perform signal synchronization and Doppler estimation based on superimposed pilot to obtain the mth user transmitted data a m Estimates 5. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 4, characterized in that: The step B2 specifically includes: C1: Using the synchronization and Doppler estimation technology of multi-branch autocorrelation, the baseband signal of the mth user positioning signal is expressed as Among them, T s is the symbol interval, x m (i) is the transmission waveform of the mth user, after the carrier is f c After modulation, the transmitted passband signal is expressed as s t (t) = Re{b(t)exp(j2πf c t)} Where Re{·} represents the real part operation; The received passband signal is denoted as s r (t) = s t (t-τ(t))+w(t) Where w(t) represents noise, τ(t) is the time-varying delay introduced by Doppler, that is, Where c represents the speed of sound in water, τ0 is the time-invariant propagation delay; The received signal is used to perform autocorrelation calculation to obtain an estimate of the unknown velocity v and acceleration a; the Doppler frequency shift is estimated, and the received signal y is converted using linear interpolation or sampling rate conversion technology based on the estimated Doppler frequency shift. T,m Doppler compensation is performed to obtain the received signal y m,d ; C2: for signal y m,d Perform FFT-based OFDM signal demodulation to obtain y FD,m ; C3: for signal y FD,m Deinterleave to obtain the signal y to be despread DI,m ; C4: Perform despreading operation, that is, Among them, c m is the spreading sequence of the mth user, The emission symbol x d,m estimates; C5: Perform symbol demapping to obtain the transmission information a m Estimates 6. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 1, characterized in that: The multi-user positioning solution is performed based on the superposition sequence in step S2, specifically including: D1: For the positioning of the mth user, based on the ultra-short baseline positioning equation, the synchronization, Doppler estimation and compensation of the m users are first performed; D2: Estimate the delay value of the mth user based on the copy correlation technology, and then obtain the relative delay value of the mth user relative to the ultra-short baseline positioning array, that is, perform a copy correlation operation on the signal received by the nth receiving element of the ultra-short baseline in, is the matched filter of the mth user, which can be directly constructed from the transmission waveform of the mth user; performing the same copy-related operation on other receiving primitives can obtain the relative delay value of the mth user relative to the five receiving primitives, that is, τ m,1 , τ m,2 , τ m,3 , τ m,4 , τ m,5 ; D3: Based on the ultra-short baseline positioning principle, the mth user is located and the positioning position is obtained.

7. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 6, characterized in that: The step D3 comprises: E1: Calculate the slope distance R; E2: calculate and obtain the user's position information; E3: According to the slant distance R and the user's orientation information, the user's position in the rectangular coordinate system is obtained.

8. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 7, characterized in that: The step E1 is specifically as follows: the position of the mth user in the base array reference coordinate system, the distance from the user to the origin of the coordinate system is R, the angles between the target and the x-axis, y-axis, and z-axis are α, β, and γ, then the coordinates of the target in the coordinate system are expressed as X=R·(cosα, cosβ, cosγ) T ,in(·) T represents the transpose of the matrix; the slant range R is obtained by the round-trip propagation delay of the reply mode, that is, Where c is the speed of sound, T tr is the round trip time of the signal.

9. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 8, characterized in that: The step E2 is specifically as follows: the ultra-short baseline positioning solution formula is uniformly written in the form of the following matrix, namely: A+B=C·u in u=(cosα,cosβ) Among them, N1 and N2 represent array element 1 and array element 2, N1 and N3 represent array element 1 and array element 3; Then N1 and N2 represent the delay difference between array element 1 and array element 2. Then N1 and N2 represent the delay difference between array element 1 and array element 3. Specifically for the positioning of the mth user, the delay τ m,1 , τ m,2 , τ m,3 , τ m,4 , τ m,5 The difference between the two is and Or other delay difference combinations; when the matrix C is full rank, the user position vector u is obtained, that is, u=C -1 (A+B) When the number of baselines involved in solving the target position information is greater than two, an overdetermined set of positioning equations is constructed. When the matrix C is full rank, the target position information is solved using the least squares principle. u=(C T C) -1 C T (A+B) The angle γ is obtained by using the following equation: cos 2 α+cos 2 β+cos 2 γ = 1.

10. A tightly coupled underwater acoustic multi-user positioning and communication method according to claim 9, characterized in that: The position of the user in the rectangular coordinate system in step E3 is: X=R·(cosα,cosβ,cosγ) T 。

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