CN108234079B - Relay time reversal underwater acoustic communication machine for multi-hop underwater acoustic network - Google Patents
Relay time reversal underwater acoustic communication machine for multi-hop underwater acoustic network Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B13/00—Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
- H04B13/02—Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0041—Arrangements at the transmitter end
- H04L1/0043—Realisations of complexity reduction techniques, e.g. use of look-up tables
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0045—Arrangements at the receiver end
- H04L1/0052—Realisations of complexity reduction techniques, e.g. pipelining or use of look-up tables
Abstract
A relay time reversal underwater acoustic communicator used for multi-hop underwater acoustic network, the transmitting part has synchronous signal module, control word head, spread spectrum modulation module, information code element, data modulation module, information frame time reversal module, framing module, power amplifier and transmitting transducer, the synchronous signal module connects framing module, the control word head connects framing module through spread spectrum modulation module, the information code element connects framing module through data modulation module, the information frame time reversal module connects framing module, framing module sends transducer through power amplifier; the receiving part is provided with a receiving transducer, a front module, an analog-to-digital converter, a synchronization module, a frame disassembling module, a control word head decoding module, a data decoder and an information frame time reversal module, the receiving transducer is connected with the analog-to-digital converter through the front module, the analog-to-digital converter is respectively connected with the synchronization module and the frame disassembling module, the synchronization module is connected with the frame disassembling module, the frame disassembling module is connected with the control word head decoding module, the data decoder and the information frame time reversal module, and the control word head decoding module is connected with the data.
Description
Technical Field
The invention relates to an underwater acoustic communicator, in particular to a relay time reversal underwater acoustic communicator for a multi-hop underwater acoustic network.
Background
With the rapid increase of the demand for long-term, real-time and large-area marine information acquisition and transmission in the fields of marine exploration, resource development, environmental monitoring, national defense safety and the like, the underwater acoustic communication and networking technology has become a hotspot and frontier of the high ocean technology. The characteristics of strong multipath interference, strong time variation, strong background noise, long time delay and the like of the underwater acoustic channel cause great challenges to the design of high-performance underwater acoustic communication and network systems.
In consideration of the technical difficulties in the aspects of transmission power, transmission rate and the like caused by directly realizing long-distance underwater acoustic communication, the design of an underwater acoustic communication network usually adopts a multi-node relay mode to realize network multi-hop transmission. Therefore, research on underwater acoustic multi-hop networks adopting relay transmission is relatively extensive.
For example, chinese patent ZL201110177853.9 discloses a routing protocol suitable for a central underwater acoustic network multi-hop network, which divides network nodes into three types: sink node, fixed node and mobile node. And the network node establishes a multi-hop route to the Sink node through the periodical broadcast route vector of the Sink node, and the node directly utilizes the route to carry out relay transmission when data are sent, thereby improving the network throughput.
Chinese patent ZL 201210071647.4 discloses a medium access control method for a distributed multi-hop underwater acoustic communication network, which balances network throughput and packet loss rate performance by adopting a dynamic competition mode, and introduces a pseudo Tone mechanism and a new competitor counting mode to solve the problems of hidden terminals and exposed terminals, thereby improving the medium control performance of the distributed multi-hop underwater acoustic network.
However, it is obvious that improving the performance of the underwater acoustic multi-hop network through the upper protocol layers of the network such as medium control, routing, etc., still needs the stable and reliable physical layer of the underwater acoustic multi-hop network as the foundation and guarantee. Under the bad underwater sound channel transmission condition, the current domestic and foreign universal underwater sound communication machine adopts a channel equalization and matching method under a point-to-point communication mode in the modulation and demodulation scheme design, and does not consider the network relay scene which can be utilized when the underwater sound multi-hop network is applied.
For example, the time reversal technology can effectively utilize the time and space focusing effects to suppress multipath interference, and the operation complexity is low, so that the time reversal technology becomes a research hotspot in the field of underwater acoustic communication in recent years and is widely researched and applied.
Chinese patent ZL201210495671.0 discloses an underwater acoustic communication device that realizes multi-channel time reversal by time-sharing to improve communication system performance; the reliability and the high efficiency of the method are shown in a phase coherent underwater communication system by combining passive time reversal and adaptive equalization in a reference (Chendongsheng, Chipshi, Schumamei time reversal combined channel equalization underwater acoustic communication system research [ J ]. acoustic technology.2011, 30(3): 195-197); the reference (Gongmaoyun, Yaohun, Panxiang, passive time reversal and adaptive equalization combined underwater acoustic communication research [ J ]. acoustic technology 2010,29(2):129-134) realizes the underwater acoustic information transmission of multiple users by using decision feedback equalization and phase-locked loop technology on the basis of the passive time reversal.
Similar to the multi-path time reversal in the point-to-point underwater acoustic communication, which can realize multi-path focusing by using space diversity, in an underwater acoustic multi-hop network, on one hand, channels among a plurality of relay nodes have space and time diversity effects and have the possibility of multi-path focusing by time reversal; on the other hand, each relay node in the multi-hop relay transmission demodulates, decodes and forwards the information frame, and actually, redundancy exists, which causes a large amount of computation and complexity for the network communication machine.
Disclosure of Invention
The invention aims to provide a relay time reversal underwater sound communication machine for a multi-hop underwater sound network, which can reduce the calculation amount and improve the performance aiming at the problem that the existing underwater sound network communication machine can not realize relay time reversal by utilizing redundancy in multi-hop relay.
The invention comprises a transmitting part and a receiving part, wherein the transmitting part is provided with a synchronous signal module, a control header module, a spread spectrum modulation module, an information frame module, a data modulation module, an information frame time reversal module, a framing module, a power amplifier and a transmitting transducer; the receiving part is provided with a receiving transducer, a front-end module, an analog-to-digital converter, a synchronization module, a frame disassembling module, a control word head decoding module, a data decoder and an information frame time reversal module, wherein the output end of the receiving transducer is connected with the input end of the front-end module, the output end of the front-end module is connected with the input end of the analog-to-digital converter, the output end of the analog-to-digital converter is respectively connected with the synchronization module and the frame disassembling module, the output end of the synchronization module is connected with the frame disassembling module, the output end of the frame disassembling module is respectively connected with the control word head decoding module, the data decoder and the information frame time reversal module, and.
The pre-module consists of a preamplifier and a band-pass filter.
In the transmitting part, the initial position of the transmitting frame format is a frame synchronization signal which is used for establishing the data demodulation time starting point of the receiving end, and meanwhile, the frame synchronization signal can be multiplexed as a probe signal for time reversal processing; the frame synchronization signal is followed by a control word head which is used for carrying information such as a source node, a destination node, relay times and the like in network transmission, and the control word head adopts spread spectrum modulation which is universal in the field to ensure reliability; the control header is followed by an information frame in which data symbols are data-modulated, such as BPSK (binary phase keying) and QPSK (quadrature phase keying), to form the information frame. Meanwhile, in order to avoid intersymbol interference caused by the frame synchronization signal and the control word head and the information frame, a guard interval is inserted between the frame synchronization signal, the control word head and the information frame.
In the relay time reversal underwater acoustic communication machine for the multi-hop underwater acoustic network, for a relay node in the multi-hop underwater acoustic network, an information frame in a transmitting signal frame format is formed by time reversal of an information frame of a receiving signal; for a source node in the multi-hop underwater acoustic network, an information frame in a transmitted signal frame format is formed by modulating information code elements by data;
the framing module is used for a relay time reversal underwater acoustic communicator of the multi-hop underwater acoustic network to form a transmission signal frame by a frame synchronization signal, a control word head and an information frame for transmission, wherein the information frame is generated by the data modulation module when the node is an information source node; when the node is a relay node, the node is generated by an information frame time reversal module.
And the spread spectrum modulation module carries out spread spectrum modulation on the control header code element.
The data modulation module is used for the network communication machine as the source node to perform data modulation such as BPSK and QPSK modulation on the information frame code element.
The information frame time reversal module is the same as the receiving part and is used for carrying out time reversal processing on the information frame of the received signal.
A receiving section:
the preamplifier and the filter are connected with the receiving transducer and used for preprocessing the received signals.
An ADC (analog-to-digital converter) is used for analog-to-digital conversion of the received signal.
The synchronization module captures a frame synchronization signal by using copy correlation operation and is used for establishing a time reference for disassembling a control word header and an information frame.
And the frame disassembling module is used for disassembling the received signal into a control word head and an information frame part for processing respectively according to the synchronously established time reference.
And the control header decoding module decodes the de-spread data of the control header part after the frame is disassembled according to the spread spectrum modulation mode of the control header part, restores the control header data and obtains control information such as a frame destination node address, relay times and the like carried by the control header according to demodulation.
And the data decoder module is used for demodulating the de-data of the information frame part after the frame is disassembled if the node is the destination node of the frame, and recovering the original information data.
The information frame time reversal module is used for directly carrying out time reversal processing on the information frame signal of the frame if the node is the relay node of the frame, and sending the information frame signal into the framing module of the transmitting part to be forwarded after adding the corresponding control word head.
If the node is the destination node of the frame, the data decoder performs data decoding on the information frame signal of the frame according to the modulation mode of the information frame signal, and restores the original information data. At this time, because the frame is subjected to time reversal processing for multiple times when the frame is relayed by multiple network nodes in multi-hop network transmission before reaching the destination node, intersymbol interference caused by underwater acoustic channel multipath is suppressed, and the performance of data decoding by the destination node can be effectively improved.
The invention aims to solve the problem of providing a method for realizing time reversal processing of an information frame through multi-hop relay under an underwater sound multi-hop relay network, thereby achieving the purpose of inhibiting multipath interference through time reversal at a destination node communication machine.
The working principle of the invention is as follows: each relay node in the underwater sound multi-hop network directly transmits the received information frame in a time reversal mode, a plurality of relay nodes in successive relay transmission of the multi-hop network sequentially perform time reversal processing and multipath focusing and then directly transmit the information frame, and finally, the information frame demodulation is only performed at a target node, so that the multipath time reversal focusing effect of the underwater sound network communication machine is obtained in a multi-hop relay mode, and engineering redundancy caused by demodulation and transmission of each relay node is avoided. In the relay time reversal, the relay node only needs to perform time reversal processing on the received information frame signal and then perform framing and forwarding without demodulation and modulation processing, so that the method can greatly reduce the operation overhead of the relay node underwater acoustic communication machine while suppressing the multipath interference by using the relay time reversal.
Compared with the existing underwater acoustic network communication machine, the underwater acoustic network communication machine has the following outstanding advantages:
firstly, as the information frame is subjected to time reversal for multiple times in the network relay multi-hop transmission process, the effects of time reversal and multi-path focusing can be obtained, and the method has better inhibition performance on underwater acoustic channel multi-path and time variation.
Secondly, as the relay multi-hop is adopted for information frame time reversal, the relay node of the data frame only needs to directly perform time reversal on the information frame and does not need to perform demodulation and decoding processing on the information frame in network multi-hop transmission, namely, only the destination node communicator of the data frame needs to perform information frame demodulation processing in network transmission, the complexity and the operation cost of the underwater sound communication relay node communicator are greatly reduced, and meanwhile, the performance of the underwater sound communicator can be obviously improved.
Drawings
Fig. 1 is a block diagram of a receiving part of a relay time reversal underwater acoustic communication device in an embodiment of the present invention.
Fig. 2 is a block diagram of the structure of the transmitting part of the relay time reversal underwater acoustic communication machine in the embodiment of the invention.
Fig. 3 is a design of a frame format of a transmission signal.
Fig. 4 is a pre-processing circuit.
FIG. 5 is a circuit for interfacing the analog-to-digital conversion and the DSP.
Detailed Description
In order to make the technical contents, features and advantages of the present invention more comprehensible, a relay time reversal underwater acoustic communication device for a multi-hop underwater acoustic network according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.
Referring to fig. 1 and 2, the embodiment of the present invention includes a transmitting portion and a receiving portion, the transmitting portion is provided with a synchronization signal module 21, a control header module 22, a spread spectrum modulation module 23, an information frame module 24, a data modulation module 25, an information frame time reversal module 26, a framing module 27, a power amplifier 28 and a transmitting transducer 29, the synchronization signal of the synchronization signal module 21 is connected to the framing module 27, the control header module 22 is connected to the framing module 27 through the spread spectrum modulation module 23, the information frame module 24 is connected to the framing module 27 through the data modulation module 25, the output end of the information frame time reversal module 26 is connected to the framing module 27, and the output end of the framing module 27 is connected to the transmitting transducer 29 through the power amplifier 28; the receiving part is provided with a receiving transducer 11, a front-end module 12, an analog-digital converter 13, a synchronization module 14, a frame disassembling module 15, a control header decoding module 16, a data decoder 17 and an information frame time reversal module 18, wherein the output end of the receiving transducer 11 is connected with the input end of the front-end module 12, the output end of the front-end module 12 is connected with the input end of the analog-digital converter 13, the output end of the analog-digital converter 13 is respectively connected with the synchronization module 14 and the frame disassembling module 15, the output end of the synchronization module 14 is connected with the frame disassembling module 15, the output end of the frame disassembling module 15 is respectively connected with the control header decoding module 16, the data decoder 17 and the information frame time reversal module 18, and the output end of the control header decoding module 16 is.
The pre-stage module 12 is composed of a pre-amplifier 121 and a band-pass filter 122.
An emission part:
in a transmitting signal, a control header adopts direct sequence spread spectrum differential phase modulation (DS-DBPSK) and m-sequence spread spectrum, the length of an m-sequence is 63 bits, the carrier frequency is 15KHz, the code element width is 15.75ms, and the data rate of the control header modulation is 63.5 bps; the information frame signal is modulated by two-phase modulation (BPSK), the carrier frequency is 15KHz, the code element width is 0.25ms, and the data rate of the information modulation is 4 kbps; the frame synchronization signal is a chirp signal with a low-end frequency of 13kHz, a high-end frequency of 18kHz and a length of 30 ms. The sampling rate is 96KHz, the carrier frequency is 15KHz, the bandwidth is 13-18KHz,
the relay time reversal communicator in the embodiment of the invention adopts a receiving and transmitting underwater acoustic transducer, such as a cylindrical piezoelectric ceramic underwater acoustic transducer with the center frequency of 16kHz produced by a medium ship reworking 726, and adopts a power amplifying electric appliance commonly used in the field to transmit signals.
An underwater acoustic communicator serving as a network source node firstly generates and transmits a signal frame, wherein the signal frame carries destination node information at a control word head as shown in fig. 3, and information data to be transmitted (such as temperature, salinity and other sensing data acquired by a sensor) is carried at an information frame part;
the signal frame firstly passes through N relay nodes (namely: the relay nodes are not destination nodes and provide multi-hop relay in network transmission) in the multi-hop network transmission, and the following processes are carried out at the relay nodes:
after receiving the signal, the relay node communicator firstly adopts copy correlation operation to carry out frame synchronization capture on the input signal, judges whether the frame synchronization arrives or not by judging whether the copy correlation result exceeds a set threshold or not and determines the starting point of the frame synchronization time as a time reference;
the frame disassembling module is used for disassembling the received signal into a control word head and an information frame part for processing respectively according to the synchronously established time reference; the control header decoding module decodes the de-spread data of the control header part after the frame is disassembled according to the spread spectrum modulation mode of the control header part, restores the control header data and obtains control information such as a frame destination node address and relay times carried by the control header according to demodulation;
because the relay node is not the destination node of the frame, the information frame signal of the frame is directly subjected to time reversal processing, and then the corresponding control word head is added for forwarding. In the multi-hop relay transmission, the ith relay node (i is 1,2,3, … N) obtains the probe new number p received by the node according to the time sequence that the N relay nodes process the information framesir(t) time reversal is carried out on the time reversal pre-processor coefficient p to obtain the time reversal pre-processor coefficient p corresponding to the relay nodeir(-t)。
Therefore, a transmission frame signal sent by a network source node sequentially passes through the ith (i is 1,2,3, … N) relay node in the underwater acoustic network multi-hop relay transmission, time reversal processing is carried out on an information frame corresponding to the transmission frame, and then a corresponding control word head is added for forwarding.
Then, assume that the impulse response of the channel from the i-1 st relay node to the i-th relay node is hi(t) satisfying the randomness of the random,
information frame s received at the ith relay node representing a convolution operationir(t) is:
in the formula, si-1(t) is the information frame signal processed and forwarded by the i-1 st relay node time reversal, nis(t) each channel information frame s received by the i-th relay node is superimposed on the information signal as interference noiseir(t) time-reversal preprocessor p through respective channelsir(-t), i.e. with pirThe convolution operation can be obtained as follows (-t):
in the formula nie(t) is a time inverse noise interference term of the ith relay node,
for each channel response after time-reverse focusing, δ (t) is approximated.
To eliminate p in the resulti(-t) ri' (t) and probe signal pi(t) performing a convolution operation of
In the formula ni(t) is an equivalent noise interference term of the ith relay node:
then, the time reversal signal r can be obtained after the time reversal processing of the ith relay nodei(t) where n is the equivalent noise interference term superimposedi(t) of (d). Approximating δ (t) in view of the channel responses of each channel after time-reverse focusing; meanwhile, considering that in the underwater acoustic multi-hop relay network, the adjacent relay demodulation distance is short, the received signal-to-noise ratio is high, and the influence of an equivalent noise item can be omitted, the following steps are provided:
ri(t)≈si-1(t) (5)
that is, the information frame signal s forwarded after the time reversal of the i-1 th relay node can be approximately obtained by the multi-hop relay transmission through the time reversal processing of the i-th relay nodei-1(t)。
Similarly, one can obtain:
ri(t)≈si-1(t)≈si-2(t)≈...≈s0(t)，(6)
wherein s is0And (t) is an information frame signal transmitted by the source node.
As can be seen from the above equations (1) to (6), in the relay time reversal underwater acoustic communication device scheme for the multi-hop underwater acoustic network proposed by the present invention, in the network transmission process, the transmitter does not decode the information frame but adds the control headers after performing the time reversal processing one by one to directly forward, that is: original transmission signal s0And (t) after the inverse processing during network relay, the data are actually directly forwarded in the relay nodes one by one through convolution of the autocorrelation of the channel impulse response and the autocorrelation of the probe signal among the (i-1) th to the (i) th relay nodes, so that the data demodulation work in the relay demodulation process is not needed. Meanwhile, in the process of the relay time reversal processing, because the relay multi-hop network can set a closer distance between adjacent nodes, the influence of the background noise item in each relay node can be approximately omitted after the time reversal processing.
In the process, after the information frame transmitted by the network source node passes through the time reversal processing of each relay node, the multipath focusing is realized, the interference caused by the multipath effect is greatly inhibited, after the information frame is received by the target node, the target node network communicator adopts copy correlation operation to carry out frame synchronization capture on the input signal, judges whether the frame synchronization arrives or not by judging whether the copy correlation result exceeds a set threshold or not, and determines the time starting point of the frame synchronization as the time reference and carries out information frame demodulation.
The specific processing procedure of the destination node communicator is as follows: the frame disassembling module is used for disassembling the received signal into a control word head and an information frame part for processing respectively according to the time reference established by the synchronization module; the control header decoding module decodes the de-spread data of the control header part after the frame is disassembled according to the spread spectrum modulation mode of the control header part, restores the control header data, the destination node communicator can start the demodulation process of the information frame according to the control information such as the frame destination node address and the relay times carried by the demodulation acquired control header, and the BPSK signal is demodulated in the DSP chip by adopting the algorithm known in the art to acquire the information code element.
The modulation and demodulation of the underwater acoustic communication machine can be realized by adopting the transmitting, receiving and processing devices, circuits and modulation and demodulation schemes commonly used in the field. For example, the receiving underwater acoustic transducer in the embodiment of the present invention is a cylindrical piezoelectric ceramic underwater acoustic transducer with a center frequency of 16kHz, which is produced by 726 th vessel rework. The front-end module in the network node communication machine consists of an AD620 low-noise front-end amplifier chip of the American AD company, a TL084 operational amplifier chip and a MAX274 switched capacitor filter chip of the Maxium company, wherein the MAX273 switched capacitor filter is set to be a band-pass filter with a pass band of 13-18 kHz. The pre-processing circuit of the underwater acoustic network communicator in the embodiment of the invention is shown in fig. 4. The output signal after preamplification and band-pass filtering is sent to an analog-digital sampling chip.
The analog-digital sampling module consists of an AD9851DDS chip and a MAX153ADC chip, and has the function that under the setting of the DSP, the DDS chip outputs a square wave signal with the frequency of 96kHz for controlling the ADC chip to perform analog-digital conversion on an input signal. Fig. 5 shows a circuit diagram of the connection between the AD9851DDS chip, the MAX153ADC chip, and the TMS320C6713 processor. In the initialization stage, the TMS320C6713 processor pairs AD9851DDS cores through IO ports GP0, GP1, GP2 and GP3Setting chip pins, setting the type and frequency of output waveform of the output pin of the AD9851 chip, wherein the output type is square wave in the embodiment, and the oscillation frequency of the output square wave is set as fs＝96kHz。
After frame synchronization is established in the network node communicator, a received signal including a control word header and an information frame is input to a subsequent ADC and TMS320C6713DSP for processing. In the technical scheme of the invention, the network relay node does not demodulate the information frame, but utilizes the probe signal to perform time reversal processing and then matches with the control word head for forwarding, so that the operation amount of the relay node network communication machine can be greatly reduced, and the engineering realization of the network node communication machine is facilitated.
Fig. 4 shows a circuit for receiving signals into an ADC and a DSP interface circuit in a relay time reversal underwater acoustic communicator for a multi-hop underwater acoustic network according to an embodiment of the present invention, and a connection mode between an AD9851DDS chip, a MAX153ADC chip, and a TMS320C6713 processor in a receiving portion of the underwater acoustic communicator according to the embodiment is described as follows: input signal is sent to input V of MAX153 chipinAfter the end of the AD9851 chip, a square wave signal with the output frequency of 96kHz is connected to WR/RDY and RD ends of the MAX153 chip to start AD conversion, after the AD conversion is finished, an INT signal of the MAX153 chip sends out a low level, the INT signal is connected with GP7/EXINT7 pins of the TMS320C6713 chip and used for triggering an external interrupt service program of the DSP chip, and data lines ED0-ED7 of the DSP are connected with data lines D0-D7 ends of the MAX153 chip U1 and input ADC conversion results. The external interrupt service program acquires the conversion data of the ADC chip and then inputs the data of the DSP chip to carry out subsequent processing in a double-buffer mode.
In the network underwater acoustic communicator of the embodiment, the steps of modulation, synchronous establishment, time reversal processing, data decoding and the like are all realized by software programming in a TMS320C6713 Digital Signal Processor (DSP) chip.
In summary, the relay time reversal underwater acoustic communication machine for the multi-hop underwater acoustic network disclosed by the invention utilizes the relay node to perform time reversal and forwarding processing on the information frame, and avoids the demodulation processing of the information frame on the relay node communication machine in the network multi-hop transmission while acquiring the time reversal multi-path focusing effect, thereby greatly reducing the real-time computation amount of the network node communication machine and facilitating the design and engineering realization of the underwater acoustic network communication machine.
Claims (8)
1. A relay time reversal underwater acoustic communicator used for multi-hop underwater acoustic network, characterized by including transmitting part and receiving part, the said transmitting part has module of synchronizing signal, control word head module, spread spectrum modulation module, information frame module, data modulation module, information frame time reversal module, framing module, power amplifier and transmitting transducer, the frame synchronizing signal of the said synchronizing signal module connects framing module, the control word head module connects framing module through spread spectrum modulation module, the information frame module connects framing module through data modulation module, the output end of the information frame time reversal module connects framing module, the output end of the framing module sends and transmits the transducer through the power amplifier; the receiving part is provided with a receiving transducer, a front-end module, an analog-to-digital converter, a synchronization module, a frame disassembling module, a control word head decoding module, a data decoder and an information frame time reversal module, wherein the output end of the receiving transducer is connected with the input end of the front-end module, the output end of the front-end module is connected with the input end of the analog-to-digital converter, the output end of the analog-to-digital converter is respectively connected with the synchronization module and the frame disassembling module, the output end of the synchronization module is connected with the frame disassembling module, the output end of the frame disassembling module is respectively connected with the control word head decoding module, the data decoder and the information frame time reversal module, and; the transmitting frame format of the transmitting part comprises a frame synchronization signal, a control word header and an information frame; after the relay node communicator receives the signal, the frame disassembling module is used for disassembling the received signal into a control word head and an information frame part for processing respectively according to the synchronously established time reference; the control header decoder decodes the de-spread data of the control header part after the frame is disassembled according to the spread spectrum modulation mode of the control header decoder, restores the control header data and obtains a frame destination node address and relay time control information carried by the control header according to demodulation; the data decoder module is used for demodulating the data of the information frame part after the frame is disassembled and recovering the original information data if the node is the destination node of the frame; the information frame time reversal module is used for directly carrying out time reversal processing on the information frame signal of the frame if the node is the relay node of the frame, and sending the information frame signal into the framing module of the transmitting part to be forwarded after adding the corresponding control word head.
2. The relay time reversal underwater acoustic communicator for a multi-hop underwater acoustic network as claimed in claim 1, wherein the pre-stage module is comprised of a preamplifier and a band pass filter.
3. The relay time reversal underwater acoustic communicator for a multi-hop underwater acoustic network as claimed in claim 1, wherein in the transmitting part, a start position of a transmission frame format is a frame synchronization signal for establishing a data demodulation time start point of a receiving end, and the frame synchronization signal is multiplexed as a probe signal for time reversal processing.
4. The relay time reversal underwater acoustic communicator for multi-hop underwater acoustic network of claim 1, wherein the frame synchronization signal is followed by a control header for carrying information of the source node and the destination node and the relay times in the network transmission.
5. The relay time reversal underwater acoustic communication machine for the multi-hop underwater acoustic network as claimed in claim 1, wherein the control word is followed by an information frame, and data modulation is performed on data symbols in the information frame to form the information frame, and the data modulation is binary phase keying or quadrature phase keying.
6. The relay time reversal underwater acoustic communication machine for the multi-hop underwater acoustic network as claimed in claim 1, wherein the pre-processing module is composed of a pre-amplifier and a band-pass filter, the receiving transducer is connected with the pre-amplifier, and the output of the pre-amplifier is connected with the band-pass filter for pre-processing the received signal.
7. The relay time reversal underwater acoustic communicator for multi-hop underwater acoustic network of claim 1, wherein the synchronization module captures a frame synchronization signal by using a copy correlation operation for establishing a time reference for performing the parsing of the control headers and the information frames.
8. The relay time reversal underwater acoustic communication machine for the multi-hop underwater acoustic network as claimed in claim 1, wherein the frame splitting module splits the received signal into the control header and the information frame part for processing respectively according to the synchronously established time reference.
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| WO2011156322A2 (en) * | 2010-06-07 | 2011-12-15 | University Of Delaware | Underwater acoustic multiple-input/multiple-output (mimo) communication systems and methods |
| CN102970123A (en) * | 2012-11-28 | 2013-03-13 | 厦门大学 | Underwater acoustic communication apparatus with timesharing-implemented multichannel time reversal |
| US9030918B2 (en) * | 2013-03-12 | 2015-05-12 | The United States Of America, As Represented By The Secretary Of The Navy | Method for mobile underwater acoustic communications |
| CN106060873A (en) * | 2016-05-18 | 2016-10-26 | 西北工业大学 | Underwater acoustic network reservation multi-access method based on active time reversal |
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| WO2011156322A2 (en) * | 2010-06-07 | 2011-12-15 | University Of Delaware | Underwater acoustic multiple-input/multiple-output (mimo) communication systems and methods |
| CN102970123A (en) * | 2012-11-28 | 2013-03-13 | 厦门大学 | Underwater acoustic communication apparatus with timesharing-implemented multichannel time reversal |
| US9030918B2 (en) * | 2013-03-12 | 2015-05-12 | The United States Of America, As Represented By The Secretary Of The Navy | Method for mobile underwater acoustic communications |
| CN106060873A (en) * | 2016-05-18 | 2016-10-26 | 西北工业大学 | Underwater acoustic network reservation multi-access method based on active time reversal |
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