CN109257316A - A kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound - Google Patents

A kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound Download PDF

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Publication number
CN109257316A
CN109257316A CN201811257487.6A CN201811257487A CN109257316A CN 109257316 A CN109257316 A CN 109257316A CN 201811257487 A CN201811257487 A CN 201811257487A CN 109257316 A CN109257316 A CN 109257316A
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signal
information
data
channel
send data
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叶东来
刘敬浩
付晓梅
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Tianjin University
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Tianjin University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2627—Modulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2649—Demodulators

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transmitters (AREA)

Abstract

The invention discloses a kind of multi-carrier modulation methods based on the sparse orthogonal frequency division multiplexing of the underwater sound, comprising: transmitting terminal: signal source generate binary bits stream information encoded after message sink coding after informationInformationData are obtained after channel codingDataSignal is mapped as after quadrature phase shift keying is modulatedSignalAfter the modulation of demodulated device, generates and send dataSend dataIn contain signalAll information；Send dataCyclic suffix and header signal are added, becomes a complete frame signal and is sent in practical underwater acoustic channel by hydrophone；Receiving end: the reception signal with cyclic prefix is obtained, removes cyclic prefix, obtains the modulation data of receiving endAfter demodulation using channel estimation and demodulator, the quadrature phase shift keying signal that is receivedBit stream is obtained by demappingBit streamIt is decoded as by channelBinary bits stream information is obtained after source coding.

Description

A kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound
Technical field
The present invention relates to digital multi-carrier transmission technical fields, more particularly on the basis of orthogonal frequency division multiplexing (OFDM) On, the thought of compressed sensing is applied to multi-carrier modulation, proposes a kind of overloading based on the sparse orthogonal frequency division multiplexing of the underwater sound Wave (SOFDM) modulator approach.
Background technique
Currently, underwater sound communication using more and more extensive.But underwater acoustic channel, because its noise is big, propagation delay is big and more The features such as diameter effect is serious, one of referred to as most challenging channel.
Orthogonal frequency division multiplexi (OFDM) can cope with the effect of the multipath in channel by adding the method for cyclic prefix It answers, eliminates intersymbol interference and inter-sub-carrier interference to a certain extent, there is preferable robustness.Therefore OFDM technology It is applied in underwater sound communication first.
But the subcarrier of OFDM is very stringent to its orthogonality requirement, it is necessary to it is absolutely orthogonal, otherwise demodulated in receiving end When will appear error, so as to cause the rising of the bit error rate.Such as: this larger feature of Doppler frequency shift in underwater acoustic channel, It just will affect the orthogonality between each subcarrier of OFDM.
Summary of the invention
The present invention provides a kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound, the present invention based on OFDM multicarrier transmission systems complete the design of SOFDM multicarrier transmitting method, in detail in conjunction with the part thought of compressed sensing See below description:
A kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound, the described method comprises the following steps:
Transmitting terminal:
Signal source generate binary bits stream information encoded after message sink coding after informationInformationThrough Data are obtained after crossing channel coding
DataSignal is mapped as after quadrature phase shift keying is modulatedSignalAfter the modulation of demodulated device, generate Send dataSend dataIn contain signalAll information；
Send dataCyclic suffix and header signal are added, becomes a complete frame signal and is sent to by hydrophone In practical underwater acoustic channel；
Receiving end:
The reception signal with cyclic prefix is obtained, removes cyclic prefix, obtains the modulation data of receiving endUsing letter After road estimation and the demodulation of demodulator, the quadrature phase shift keying signal that is received
Bit stream is obtained by demappingBit streamIt is decoded as by channel It is being obtained after information source source coding To binary bits stream information.
Wherein, the demodulator specifically:
Wherein, G is dictionary matrix, and generation method is as follows: G=(g0,0,g0,M-1,...,gk,m,...,gN-1,0, ...gN-1,M-1)
Wherein, gk,mIndicate k-th of subcarrier, the m times aliasing, expression formula is as follows:
gk,m[n]=δ [(n-m Δ) modN] * gk[n]
N=0,1,2 ..., N-1,
K=0,1,2 ..., N-1,
M=0,1,2 ..., M-1,
Wherein, Domain Index, frequency domain index and delay index, Δ indicate the time span of delay when n, k, m are respectively represented, Mod is remainder operation, and N is the number of orthogonal sub-carriers in OFDM, and M is the number of same frequency subcarrier extension, and δ [] is punching Swash function, gK, mSampled value when [n] is the subcarrier the m times multiplexing that frequency is k in dictionary matrix G, gk[n] is dictionary matrix G Middle frequency is that the subcarrier expression formula of k is as follows:
K=0,1,2 ..., N-1,
N=0,1,2 ..., N-1.
The beneficial effect of the technical scheme provided by the present invention is that:
1, the present invention is based on the thoughts of compressed sensing, propose a kind of based on the sparse OFDM multi-carrier tune of the underwater sound Method (SOFDM) processed replaces the fast Fourier in traditional OFDM to change (FFT/ with the rarefaction representation in compressed sensing IFFT) modulation /demodulation；
2, the present invention is by the thought of compressed sensing being applied in multi-carrier modulation, is improved on the basis of OFDM The performance of communication system, and the quality of underwater sound communication is further improved, realize better communication；
3, the present invention is based on the concepts of OFDM and compressed sensing to propose sparse OFDM multi-carrier transmission, passes through Design to different extension multiples selects carrier wave matrix of the dictionary of better performances as modulation when, to reduce the bit error rate.
Detailed description of the invention
Fig. 1 is the transceiver system block diagram of SOFDM；
Fig. 2 is BER (bit error rate) performance map of SOFDM under different aliased coefficients.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, embodiment of the present invention is made below further Ground detailed description.
Embodiment 1
The embodiment of the present invention devises a kind of multicarrier frequency division based on OFDM and compressed sensing suitable for underwater sound communication It is multiplexed modulator approach, referred to as SOFDM.The embodiment of the present invention based on OFDM, with the dictionary matrix used in compressed sensing come Instead of the part FFT/IFFT in traditional OFDM multi-carrier modulation, the bit error rate of system is reduced, method includes the following steps:
As shown in Figure 1, signal source generate binary bits stream information encoded after message sink coding after informationInformation after codingData are obtained after channel codingDataIt is reflected after QPSK (quadrature phase shift keying) modulation It penetrates as QPSK signalSignalAfter SOFDM modulator, generates and send dataSend dataIn contain QPSK SignalAll information.After addition cyclic suffix and header signal, becomes a complete frame signal and sent by hydrophone Into practical underwater acoustic channel.
After underwater acoustic channel, header signal is identified and synchronizes, the available band cyclic prefix in receiving end Reception signal.Then remove cyclic prefix, obtains the SOFDM data of receiving endIt is demodulated using channel estimation and SOFDM After device demodulation, the QPSK signal that is receivedBit stream is obtained using QPSK demappingBit streamBy letter Road decoding Binary bits stream information is obtained after source coding.
Embodiment 2
The scheme in embodiment 1 is further introduced below with reference to specific calculation formula, example, it is as detailed below Description:
One, transmitting terminal
The modulated process of transmitting terminal SOFDM modulator indicates as follows:
Wherein,For QPSK signal,To pass through modulated SOFDM signal.G is dictionary matrix, and generation method is such as Under: G=(g0,0,g0,M-1,...,gk,m,...,gN-1,0,...gN-1,M-1)(2)
Wherein, gk,mIndicate k-th of subcarrier, the m times aliasing, expression formula is as follows:
gk,m[n]=δ [(n-m Δ) modN] * gk[n] (3)
N=0,1,2 ..., N-1,
K=0,1,2 ..., N-1,
M=0,1,2 ..., M-1,
Wherein, Domain Index, frequency domain index and delay index, Δ indicate the time span of delay when n, k, m are respectively represented, Mod is remainder operation, and N is the number of orthogonal sub-carriers in OFDM.M is the number of same frequency subcarrier extension, and δ [] is punching Swash function, gK, mSampled value when [n] is the subcarrier the m times multiplexing that frequency is k in dictionary matrix G, gk[n] is dictionary matrix G Middle frequency is the subcarrier of k, while also referring to the orthogonal sub-carriers of OFDM, and expression formula is as follows:
K=0,1,2 ..., N-1,
N=0,1,2 ..., N-1,
In specific modulated process, since the dimension in formula (1) is than big, so being tracked in practical operation using base (Basic Pursuit, BP) algorithm is realized, that is, finds l in all solution vectors under the conditions of meeting formula (1)0Norm minimum Solution vector, mathematic(al) representation is as follows:
Wherein, | | ﹒ | |l0For the l of vector0Norm.
It is modulation data of the input signal after SOFDM modulators modulate according to the data that above formula solves.
Two, receiving end
In the case where header signal identifies and synchronizes, removal receives the cyclic prefix of signal.Modulated signal at this timeIn water Transmission process in Acoustic channel can indicate are as follows:
Wherein,It is to receive signal,To send signal, H is channel matrix,It is additive white Gaussian noise.
It can be indicated in the data that receiving end obtain after channel equalization and channel estimation in receiving end demodulating process Are as follows:
Wherein,For the QPSK signal after SOFDM is demodulated；For the data obtained after channel estimation and equilibrium.
It is hereby achieved that the QPSK signal receivedBit stream is being obtained after QPSK demappingBit stream Binary bits stream information is obtained after channel decoding and source coding.
The emulation of Matlab is then carried out to this method, Fig. 2 is simulation result.As seen from Figure 2 in same symbol Under time span, influence of the different sub-carrier extension number to system performance in ofdm system and SOFDM system.It is imitative at this In very, it is found that under same symbol time length, the bit error rate performance of the SOFDM system of this method compares ofdm system It is good, and with the increase of extension multiple, the bit error rate performance of system is gradually being promoted.Especially as M=3 and M=7, by In the increase of extension multiple, the atomicity of dictionary matrix G is consequently increased, and the dictionary atomic structure between each subcarrier Even closer, the sparsity of modulated SOFDM signal also becomes more preferably, can preferably reduce underwater acoustic channel to transmission signal Influence.
It will be appreciated by those skilled in the art that attached drawing is the schematic diagram of a preferred embodiment, the embodiments of the present invention Serial number is for illustration only, does not represent the advantages or disadvantages of the embodiments.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.

Claims (2)

1. a kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound, which is characterized in that the method includes with Lower step:
Transmitting terminal:
Signal source generate binary bits stream information encoded after message sink coding after informationInformationBy letter Data are obtained after road coding
DataSignal is mapped as after quadrature phase shift keying is modulatedSignalAfter the modulation of demodulated device, generates and send DataSend dataIn contain signalAll information；
Send dataCyclic suffix and header signal are added, becomes a complete frame signal and reality is sent to by hydrophone In underwater acoustic channel；
Receiving end:
The reception signal with cyclic prefix is obtained, removes cyclic prefix, obtains the modulation data of receiving endEstimate using channel After the demodulation of meter and demodulator, the quadrature phase shift keying signal that is received
Bit stream is obtained by demappingBit streamIt is decoded as by channel Binary system ratio is obtained after source coding Special stream information.
2. a kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound according to claim 1, feature It is, the demodulator specifically:
Wherein, G is dictionary matrix, and generation method is as follows: G=(g0,0,g0,M-1,...,gk,m,...,gN-1,0,...gN-1,M-1)
Wherein, gk,mIndicate k-th of subcarrier, the m times aliasing, expression formula is as follows:
gk,m[n]=δ [(n-m Δ) modN] * gk[n]
N=0,1,2 ..., N-1,
K=0,1,2 ..., N-1,
M=0,1,2 ..., M-1,
Wherein, Domain Index, frequency domain index and delay index, Δ indicate the time span of delay, mod when n, k, m are respectively represented For remainder operation, N is the number of orthogonal sub-carriers in OFDM, and M is the number of same frequency subcarrier extension, and δ [] is impulse Function, gk,mSampled value when [n] is the subcarrier the m times multiplexing that frequency is k in dictionary matrix G, gk[n] is in dictionary matrix G Frequency is that the subcarrier expression formula of k is as follows:
K=0,1,2 ..., N-1,
N=0,1,2 ..., N-1.
CN201811257487.6A 2018-10-26 2018-10-26 A kind of multi-carrier modulation method based on the sparse orthogonal frequency division multiplexing of the underwater sound Pending CN109257316A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111431627A (en) * 2020-03-25 2020-07-17 哈尔滨工程大学 Dynamic frequency selection method and underwater current field communication method based on dynamic multi-carrier

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Publication number Priority date Publication date Assignee Title
CN103701749A (en) * 2014-01-10 2014-04-02 厦门大学 Method of obtaining underwater acoustic channel reciprocity by using compressed sensing
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CN103873422B (en) * 2014-04-09 2017-03-08 厦门大学 Multi-path jamming removing method in underwater sound ofdm system symbol
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CN103873422B (en) * 2014-04-09 2017-03-08 厦门大学 Multi-path jamming removing method in underwater sound ofdm system symbol
CN106130947A (en) * 2016-06-13 2016-11-16 天津大学 A kind of Large Copacity multi-carrier modulation method with the many ripples of frequency
CN106789809A (en) * 2016-12-02 2017-05-31 天津大学 A kind of non-orthogonal multi-carrier transmission method

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111431627A (en) * 2020-03-25 2020-07-17 哈尔滨工程大学 Dynamic frequency selection method and underwater current field communication method based on dynamic multi-carrier
CN111431627B (en) * 2020-03-25 2021-09-28 哈尔滨工程大学 Dynamic frequency selection method and underwater current field communication method based on dynamic multi-carrier

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Application publication date: 20190122