CN107454024A - A kind of underwater sound OFDM MFSK channel equalization methods based on Virtual time reversal mirror - Google Patents
A kind of underwater sound OFDM MFSK channel equalization methods based on Virtual time reversal mirror Download PDFInfo
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Abstract
The invention discloses a kind of underwater sound OFDM MFSK channel equalization methods based on Virtual time reversal mirror, belong to technical field of underwater acoustic communication.The present invention adds linear FM signal by head and the tail of the transmitting terminal in a frame data；Receiving terminal detects to frame preamble, completes data cutout and Doppler factor estimation, and carry out Doppler effect correction to reception signal；High-precision channel impulse response estimation is carried out using the frame preamble after Doppler effect correction；Virtual time reversal channel equalization is carried out to data according to the channel impulse response result estimated；Finally the data after equilibrium are demodulated.The present invention carries out Doppler's estimation using the linear FM signal of data head and the tail, avoids the problem of existing using simple signal；The high accuracy that underwater acoustic channel is realized using orthogonal matching pursuit algorithm is estimated, traditional passive time reversal mirror is avoided due to performance loss caused by detectable signal, effectively increases performance of the OFDM MFSK underwater sound communication systems under way extended channel more than serious channel.
Description
Technical Field
The invention belongs to the technical field of underwater acoustic communication, and particularly relates to an underwater acoustic OFDM-MFSK channel equalization method based on a virtual time reversal mirror.
Background
The OFDM-MFSK is a modulation technology combining a multi-carrier technology and MFSK, in the implementation process, a transmitting end of the OFDM-MFSK divides all sub-carriers into a group by M elements, information mapping is carried out in an MFSK mode, a receiving end carries out detection on MFSK signals in a noncoherent mode, and channel estimation and equalization processes are not needed. The OFDM-MFSK is compatible with the high communication rate of a multi-carrier modulation technology, the robust performance of the MFSK modulation is reserved, and compared with Orthogonal Frequency Division Multiplexing (OFDM) modulation, the transmission rate and the robust performance can be well balanced.
The underwater channel is one of the most sophisticated wireless channels to date, has severe multipath spreading and doppler spreading, and has a limited available bandwidth. Because the transmission speed of the acoustic wave in water is slow, when two communication parties move relatively, the received signal is compressed and expanded to generate Doppler frequency offset, while the multipath expansion causes the coherent multipath signal to generate intersymbol interference (ISI) when reaching a receiving end, and in a multi-carrier system, the system is influenced by serious intersymbol interference (ISI) due to the large multipath expansion. In order to eliminate ISI, the system needs to add a long cyclic prefix for cancellation, thereby reducing the frequency band utilization of the system.
In order to effectively reduce the influence of ISI, a student applies a passive time reversal mirror technology to a multi-carrier OFDM-MFSK system, and realizes the shortening of a channel by utilizing good time compression and space focusing characteristics of the time reversal mirror technology. Based on this, the scholars propose to apply a Virtual Time Reversal Mirror (VTRM) technique to the OFDM system, and the method first uses a detection signal and a matching tracking algorithm to accurately estimate the channel impulse response, then performs time Reversal on the estimated result, and performs convolution with the signal to complete channel equalization.
In summary, the time reversal mirror technology can effectively reduce the performance loss caused by the multipath expansion of the channel to the system, but the method adopts the matching tracking algorithm to estimate the channel, although the method has advantages compared with the traditional matching filtering method, the selected atoms have no orthogonality, the estimation effect has a certain deviation from the true value, and the single-frequency signal is adopted to carry out doppler estimation, so that the estimation stability and accuracy are obviously reduced under the condition of the channel with serious multipath expansion, and the larger power of the system is sacrificed.
The invention utilizes the linear frequency modulation signals of the head and the tail of the data to carry out Doppler estimation, thereby effectively avoiding the problems existing in the adoption of single-frequency signals; meanwhile, an orthogonal matching pursuit algorithm is adopted to further improve the channel estimation precision; and the virtual time reversal mirror is applied to the OFDM-MFSK underwater acoustic communication system.
Disclosure of Invention
The invention aims to provide an underwater sound OFDM-MFSK channel equalization method based on a virtual time reversal mirror, which can effectively solve the performance loss caused by channel multipath expansion to an underwater sound OFDM-MFSK communication system.
The purpose of the invention is realized as follows:
the invention discloses an underwater sound OFDM-MFSK channel equalization method based on a virtual time reversal mirror, which comprises the following specific implementation steps:
(1) the transmitting end adds linear frequency modulation signals at the head and the tail of a frame of data;
(2) the receiving end detects the preamble signal before the frame, finishes data interception and Doppler factor estimation, and performs Doppler compensation on the received signal;
(3) performing high-precision channel impulse response estimation by using the frame preamble after Doppler compensation;
(4) performing virtual time reversal channel equalization on the data according to the estimated channel impulse response result;
(5) and demodulating the equalized data.
For an underwater acoustic OFDM-MFSK channel equalization method based on a virtual time reversal mirror, the bandwidth of the chirp signal in the step (1) is the system working bandwidth, the time product of the bandwidth of the chirp signal and the chirp signal is larger than 100, and the length of a guard interval between data and the two chirp signals is larger than the maximum multipath extension length of a channel.
For an underwater acoustic OFDM-MFSK channel equalization method based on a virtual time reversal mirror, the concrete implementation steps of the step (2) include:
(2.1) performing matched filtering by using the linear frequency modulation signals at the head and the tail of the data, performing correlation operation on the received data by using the synchronous signals as reference signals, searching peak coordinate points of the synchronous signals before and after the frame, and calculating the time interval of the two signals;
and (2.2) calculating the average Doppler factor of the whole frame of data, and completing the Doppler compensation of the received signal by adopting a linear interpolation method according to the average Doppler factor.
For an underwater acoustic OFDM-MFSK channel equalization method based on a virtual time reversal mirror, the concrete implementation steps of the step (3) include:
and (3.1) taking the frame preamble after Doppler compensation as a detection signal, and finishing estimation of underwater multi-path channel impulse response by adopting an orthogonal matching tracking algorithm to obtain time delay and amplitude information of each multi-path.
Preferably, the specific implementation steps of the orthogonal matching pursuit algorithm in step (3.1) include:
(3.1.1) construction of a linearized model of the sparse channel
y＝Φx+v
Wherein, y ∈ RMFor channel observation vectors, x ∈ RNFor the sparse channel to be estimated, v ∈ RMAs a channel noise vector, Φ ∈ RM×NIs a measurement matrix (or atomic pool) and can be expressed asThe observation matrix is a Topritz matrix formed by detection signals;
(3.1.2) initializing residual r0Y, index setThe iteration index i is 1,
(3.1.3) find the atom in the measurement matrix Φ that best matches the residual:
(3.1.4) adding a support set Λi＝Λi-1∪{λi}, augmentation matrix
(3.1.5) approximating the observation vector with existing atoms in the index set:
(3.1.6) update residual:
(3.1.7) if i is less than k, adding 1 to the iteration index, and returning to the step (3.1.3); if i is k, the final channel estimation result is obtained
For an underwater acoustic OFDM-MFSK channel equalization method based on a virtual time reversal mirror, the specific implementation manner of the step (4) is as follows: and after the estimated channel impulse response is subjected to time reversal, the estimated channel impulse response is convoluted with the received data to complete virtual time reversal channel equalization of the data.
For an underwater acoustic OFDM-MFSK channel equalization method based on a virtual time reversal mirror, the concrete implementation steps of the step (5) include:
(5.1) performing parallel-to-serial conversion on the data, and removing the cyclic prefix and the cyclic suffix;
(5.2) operating the DFT to obtain all subcarrier frequency domain data;
and (5.3) performing modulus operation on the data, dividing the data into a group according to M elements, and calculating the bit number represented by the maximum energy value of each group of data to realize data demodulation.
The invention has the beneficial effects that: the invention discloses an underwater sound OFDM-MFSK channel equalization method based on a virtual time reversal mirror, which adopts linear frequency modulation signals of the head and the tail of a frame of data to complete the estimation of data Doppler, and has better stability and precision in a fading underwater sound channel compared with single-frequency signal Doppler estimation; the Doppler compensation is realized by adopting linear interpolation to effectively reduce the system calculation amount;
meanwhile, the invention uses the Doppler compensated frame preamble signal for channel estimation, thereby avoiding the use of detection signals and improving the power utilization rate of the system; and the orthogonal matching pursuit algorithm is utilized to realize the high-precision estimation of the underwater acoustic channel, the channel equalization of the OFDM-MFSK system is realized through the convolution operation with the received signal, the signal-to-noise ratio of the system is effectively improved, and the influence of the multi-path expansion of the channel on the performance of the system is reduced.
Drawings
FIG. 1 is a schematic diagram of a transmitting frame structure of an OFDM-MFSK underwater acoustic communication system in the present invention;
fig. 2 is a schematic diagram of signal processing for performing virtual time reversal at the receiving end of the OFDM-MFSK underwater acoustic communication system in the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The invention discloses an underwater sound OFDM-MFSK channel equalization method based on a virtual time reversal mirror, which comprises the following specific implementation steps:
(1) the transmitting end adds linear frequency modulation signals at the head and the tail of a frame of data;
(2) the receiving end detects the preamble signal before the frame, finishes data interception and Doppler factor estimation, and performs Doppler compensation on the received signal;
(3) performing high-precision channel impulse response estimation by using the frame preamble after Doppler compensation;
(4) performing virtual time reversal channel equalization on the data according to the estimated channel impulse response result;
(5) and demodulating the equalized data.
(1) The transmitting end adds linear frequency modulation signals at the head and the tail of a frame of data;
referring to fig. 1, according to the structure of a transmission frame, a chirp signal preceding data is referred to as a frame preamble signal, and a chirp signal following data is referred to as a frame postamble. The parameters of the two chirp signals are consistent, and the length of the guard interval between the data and the two chirp signals is greater than the maximum multipath extension length of the channel. The OFDM-MFSK data block is formed by adding a cyclic prefix and a cyclic postfix to a time domain OFDM-MFSK symbol, wherein the cyclic prefix is to copy data behind the OFDM-MFSK symbol to a position before the symbol, and the cyclic postfix is to copy data in front of the OFDM-MFSK symbol to a position after the symbol.
(2) The receiving end detects the preamble signal before the frame, finishes data interception and Doppler factor estimation, and performs Doppler compensation on the received signal;
carrying out correlation operation on received data by taking a synchronous signal as a reference signal, searching peak value coordinate points of the synchronous signal before and after a frame, and calculating a time interval T of the two signalsrThe Doppler factor of the entire data block is calculated according to the following formula
Wherein, TtIs the time interval between the transmission of two chirp signals in a frame signal.
Assuming that the vector of the original sampling point is x, setting the new sampling point after Doppler compensation according to the Doppler factor obtained by calculation as the positionThe amplitude of the Doppler compensated signal is completed by adopting a linear interpolation mode.
Setting the function f (x) in the interval [ x0,x1]The function value of the two end points is f (x)0) And f (x)1) The interval [ x ] is approximated using a linear function l (x) ═ ax + b0,x1]F (x) by selecting parameters a and b such that L (x)0)＝f(x0)，L(x1)＝f(x1) The expression of L (x) can be obtained from two points of the linear equation
Combining formula (2) and the new sampling point locationThe doppler compensation of the received signal can be completed.
(3) Performing high-precision channel impulse response estimation by using the frame preamble after Doppler compensation;
the invention takes the preamble before the frame after Doppler compensation as a detection signal and adopts an Orthogonal Matching Pursuit (OMP) algorithm to finish high-precision estimation of the underwater acoustic channel. Compared with a Matching Pursuit (OMP) algorithm, the OMP algorithm increases an orthogonalization process of alternative atoms, can reduce residual errors and improve channel estimation precision, and the specific steps of the OMP algorithm are given as follows:
now consider a linearized model of a sparse channel
y＝Φx+v (3)
Wherein, y ∈ RMFor channel observation vectors, x ∈ RNFor the sparse channel to be estimated, v ∈ RMAs a channel noise vector, Φ ∈ RM×NIs a measurement matrix (or atomic pool) and can be expressed asIs an atom, in the present invention the observation matrix is a Topritz matrix formed by the probe signals.
(3.1) initialization residual r0Y, index setThe iteration index i is 1,
(3.2) finding the atom in the measurement matrix Φ that best matches the residual:
(3.3) adding a support set Λi＝Λi-1∪{λi}, augmentation matrix
(3.4) approximating the observation vector with the existing atoms in the index set:
(3.5) updating residual error:
(3.6) if i is less than k, adding 1 to the iteration index, and returning to the step (3.2); if i is k, the final channel estimation result is obtained
(4) Performing virtual time reversal channel equalization on the data according to the estimated channel impulse response result;
with reference to fig. 2, according to a signal processing block diagram of virtual time reversal at the receiving end of the OFDM-MFSK system, it is assumed that no doppler effect exists after the doppler estimation and compensation process of the system at the previous stage.
Assuming that the transmitted data is s [ n ] and the underwater acoustic channel impulse response is h [ n ], the received data r [ n ] is expressed as follows:
wherein,representing a convolution operation, z [ n ]]Representing the channel noise.
Assuming that the estimated channel impulse response is h [ n ], the received data can be expressed as the time-reversal processing
In the formula,for the virtual inverse Q function, z' [ n ]]Is a time-reversed processed noise component.
The Q function is actually an equivalent total channel processed by the system virtual time reversal mirror, and if the channel estimation is correct, the result is an autocorrelation function of channel impulse response. When the channel is complex, the Q function is approximate to a Sinc function and is expressed as a main peak with concentrated energy and lower side lobes, so that the virtual time reversal mirror technology realizes channel compression and shortening and completes channel equalization.
(5) Demodulating the equalized data;
the data are subjected to parallel-serial conversion, cyclic prefixes and cyclic suffixes are removed, DFT operation is carried out to obtain all subcarrier frequency domain data, the data are subjected to modulus extraction and are divided into a group according to M elements, the bit number represented by the maximum energy value of each group of data is calculated, and data demodulation is achieved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. An underwater sound OFDM-MFSK channel equalization method based on a virtual time reversal mirror is characterized by comprising the following specific implementation steps:
(1) the transmitting end adds linear frequency modulation signals at the head and the tail of a frame of data;
(2) the receiving end detects the preamble signal before the frame, finishes data interception and Doppler factor estimation, and performs Doppler compensation on the received signal;
(3) performing high-precision channel impulse response estimation by using the frame preamble after Doppler compensation;
(4) performing virtual time reversal channel equalization on the data according to the estimated channel impulse response result;
(5) and demodulating the equalized data.
2. The underwater acoustic OFDM-MFSK channel equalization method based on the virtual time reversal mirror as claimed in claim 1, wherein: the bandwidth of the chirp signal in the step (1) is a system working bandwidth, the time product of the bandwidth of the chirp signal and the chirp signal is more than 100, and the length of a guard interval between data and two chirp signals is more than the maximum multipath extension length of a channel.
3. The method for underwater acoustic OFDM-MFSK channel equalization based on virtual time reversal mirror as claimed in claim 1, wherein the step (2) is implemented by the following steps:
(2.1) performing matched filtering by using the linear frequency modulation signals at the head and the tail of the data, performing correlation operation on the received data by using the synchronous signals as reference signals, searching peak coordinate points of the synchronous signals before and after the frame, and calculating the time interval of the two signals;
and (2.2) calculating the average Doppler factor of the whole frame of data, and completing the Doppler compensation of the received signal by adopting a linear interpolation method according to the average Doppler factor.
4. The method for underwater acoustic OFDM-MFSK channel equalization based on virtual time reversal mirror as claimed in claim 1, wherein the step (3) is implemented by:
and (3.1) taking the frame preamble after Doppler compensation as a detection signal, and finishing estimation of underwater multi-path channel impulse response by adopting an orthogonal matching tracking algorithm to obtain time delay and amplitude information of each multi-path.
5. The method for underwater acoustic OFDM-MFSK channel equalization based on virtual time reversal mirror as claimed in claim 1, wherein the step (4) is implemented in a specific manner as follows: and after the estimated channel impulse response is subjected to time reversal, the estimated channel impulse response is convoluted with the received data to complete virtual time reversal channel equalization of the data.
6. The method for underwater acoustic OFDM-MFSK channel equalization based on virtual time reversal mirror as claimed in claim 1, wherein the step (5) is implemented by:
(5.1) performing parallel-to-serial conversion on the data, and removing the cyclic prefix and the cyclic suffix;
(5.2) operating the DFT to obtain all subcarrier frequency domain data;
and (5.3) performing modulus operation on the data, dividing the data into a group according to M elements, and calculating the bit number represented by the maximum energy value of each group of data to realize data demodulation.
7. The method for underwater acoustic OFDM-MFSK channel equalization based on virtual time reversal mirror as claimed in claim 4, wherein the step (3.1) of implementing the orthogonal matching pursuit algorithm includes:
(3.1.1) construction of a linearized model of the sparse channel
y＝Φx+v
Wherein, y ∈ RMFor channel observation vectors, x ∈ RNFor the sparse channel to be estimated, v ∈ RMAs a channel noise vector, Φ ∈ RM ×NIs a measurement matrix (or atomic pool) and can be expressed as The observation matrix is a Topritz matrix formed by detection signals;
(3.1.2) initializing residual r0Y, index setThe iteration index i is 1,
(3.1.3) find the atom in the measurement matrix Φ that best matches the residual:
(3.1.4) adding a support set Λi＝Λi-1∪{λi}, augmentation matrix
(3.1.5) approximating the observation vector with existing atoms in the index set:
<mrow> <msub> <mover> <mi>h</mi> <mo>^</mo> </mover> <mrow> <mi>&Lambda;</mi> <mi>i</mi> </mrow> </msub> <mo>=</mo> <mi>arg</mi> <munder> <mi>min</mi> <msub> <mi>h</mi> <mrow> <mi>&Lambda;</mi> <mi>i</mi> </mrow> </msub> </munder> <mo>|</mo> <mo>|</mo> <mi>y</mi> <mo>-</mo> <msub> <mover> <mi>&Psi;</mi> <mo>~</mo> </mover> <mi>i</mi> </msub> <msub> <mi>h</mi> <mrow> <mi>&Lambda;</mi> <mi>i</mi> </mrow> </msub> <mo>|</mo> <mo>|</mo> </mrow>
(3.1.6) update residual:
<mrow> <msub> <mi>r</mi> <mi>i</mi> </msub> <mo>=</mo> <mi>y</mi> <mo>-</mo> <msub> <mover> <mi>&Psi;</mi> <mo>~</mo> </mover> <mi>i</mi> </msub> <msub> <mover> <mi>h</mi> <mo>^</mo> </mover> <mrow> <mi>&Lambda;</mi> <mi>i</mi> </mrow> </msub> </mrow>
(3.1.7) if i is less than k, adding 1 to the iteration index, and returning to the step (3.1.3); if i is k, the final channel estimation result is obtained
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN109150772A (en) * | 2018-07-13 | 2019-01-04 | 哈尔滨工程大学 | A kind of underwater acoustic channel delay time estimation method based on orthogonal matching pursuit |
| CN109921811A (en) * | 2019-02-28 | 2019-06-21 | 厦门大学 | A kind of underwater acoustic communication method, apparatus and system |
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| CN110808928A (en) * | 2019-10-31 | 2020-02-18 | 苏州桑泰海洋仪器研发有限责任公司 | Orthogonal multi-carrier Doppler estimation calculation method based on channel sparsity detection |
| CN112187697A (en) * | 2020-11-25 | 2021-01-05 | 鹏城实验室 | Underwater acoustic communication detection signal generation method, device, equipment and storage medium |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008157609A2 (en) * | 2007-06-18 | 2008-12-24 | University Of Connecticut | Apparatus, systems and methods for enhanced multi-carrier based underwater acoustic communications |
| CN103905355A (en) * | 2014-03-28 | 2014-07-02 | 哈尔滨工程大学 | Virtual time reversal underwater sound OFDM channel equalization method |
| CN103944848A (en) * | 2014-01-08 | 2014-07-23 | 华南理工大学 | Underwater acoustic anti-Doppler multicarrier modulation and demodulation method based on linear frequency modulation and device thereof |
| CN104184694A (en) * | 2014-09-11 | 2014-12-03 | 东南大学 | Grouped frequency spread OFDM communication method applied to remote underwater acoustic channel |
| CN106559144A (en) * | 2016-11-15 | 2017-04-05 | 哈尔滨工程大学 | OFDM MFSK underwater acoustic communication methods based on technology time reversal |
-
2017
- 2017-07-24 CN CN201710606202.4A patent/CN107454024A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008157609A2 (en) * | 2007-06-18 | 2008-12-24 | University Of Connecticut | Apparatus, systems and methods for enhanced multi-carrier based underwater acoustic communications |
| CN103944848A (en) * | 2014-01-08 | 2014-07-23 | 华南理工大学 | Underwater acoustic anti-Doppler multicarrier modulation and demodulation method based on linear frequency modulation and device thereof |
| CN103905355A (en) * | 2014-03-28 | 2014-07-02 | 哈尔滨工程大学 | Virtual time reversal underwater sound OFDM channel equalization method |
| CN104184694A (en) * | 2014-09-11 | 2014-12-03 | 东南大学 | Grouped frequency spread OFDM communication method applied to remote underwater acoustic channel |
| CN106559144A (en) * | 2016-11-15 | 2017-04-05 | 哈尔滨工程大学 | OFDM MFSK underwater acoustic communication methods based on technology time reversal |
Non-Patent Citations (1)
| Title |
|---|
| 夏梦璐: "浅水起伏环境中模型-数据结合水声信道均衡技术", 《中国博士学位论文全文数据库 信息科技辑》 * |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109150772A (en) * | 2018-07-13 | 2019-01-04 | 哈尔滨工程大学 | A kind of underwater acoustic channel delay time estimation method based on orthogonal matching pursuit |
| CN108919222A (en) * | 2018-07-17 | 2018-11-30 | 武汉大学 | A kind of phase-coherent accumulation detection method for even accelerated motional objects |
| CN109921811A (en) * | 2019-02-28 | 2019-06-21 | 厦门大学 | A kind of underwater acoustic communication method, apparatus and system |
| CN109921811B (en) * | 2019-02-28 | 2020-07-17 | 厦门大学 | Underwater acoustic communication method |
| CN110247865A (en) * | 2019-06-03 | 2019-09-17 | 重庆邮电大学 | The optimization method of pre-processing filter in time reversal multi-user's secure transmission system |
| CN110808928A (en) * | 2019-10-31 | 2020-02-18 | 苏州桑泰海洋仪器研发有限责任公司 | Orthogonal multi-carrier Doppler estimation calculation method based on channel sparsity detection |
| CN110808928B (en) * | 2019-10-31 | 2021-12-10 | 苏州桑泰海洋仪器研发有限责任公司 | Orthogonal multi-carrier Doppler estimation calculation method based on channel sparsity detection |
| CN112187697A (en) * | 2020-11-25 | 2021-01-05 | 鹏城实验室 | Underwater acoustic communication detection signal generation method, device, equipment and storage medium |
| CN115037386A (en) * | 2022-05-16 | 2022-09-09 | 广西民族大学 | Bionic communication signal simulation test method |
| CN117097413A (en) * | 2023-08-25 | 2023-11-21 | 北京理工大学 | Multi-sequence merging and balancing single-array element virtual time reversal underwater acoustic communication method |
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