CN110351209A - A kind of self-adaptive underwater communication means - Google Patents

A kind of self-adaptive underwater communication means Download PDF

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Publication number
CN110351209A
CN110351209A CN201910590940.3A CN201910590940A CN110351209A CN 110351209 A CN110351209 A CN 110351209A CN 201910590940 A CN201910590940 A CN 201910590940A CN 110351209 A CN110351209 A CN 110351209A
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channel
adaptive
self
transmitting terminal
prediction
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CN201910590940.3A
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Inventor
韩笑
吴雨珊
王大宇
殷敬伟
张锦灿
葛威
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Harbin Engineering University
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Harbin Engineering University
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    • 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
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0212—Channel estimation of impulse response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0008—Modulated-carrier systems arrangements for allowing a transmitter or receiver to use more than one type of modulation
    • 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
    • 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
    • H04L27/2697—Multicarrier modulation systems in combination with other modulation techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26

Abstract

The present invention relates to a kind of underwater acoustic communication method fields, and in particular to a kind of OFDM underwater acoustic communication method of Adaptive Modulation and power distribution based on channel estimating.This method comprises: transmitting terminal sends test signal, receiving end is handled signal is received, channel impulse response estimation result when estimation obtains；Time domain channel impulse response is predicted using adaptive channel prediction technique；Prediction channel result is fed back into transmitting terminal by signalling, channel state information needed for obtaining Adaptive Transmission；Transmitting terminal determines the messaging parameter of each subcarrier according to channel state information based on self-adjusted block algorithm, and carries out adaptive modulation and power allocation according to messaging parameter sub-carrier；Transmitting terminal transmitting OFDM signal realizes self-adaptive underwater communication.Channel estimating is carried out in the time domain, improves precision of prediction while reducing feedback redundancy；Bit and power allocation is carried out using self-adjusted block algorithm sub-carrier, improves the practicability under foreign environment.

Description

A kind of self-adaptive underwater communication means
Technical field
The present invention relates to a kind of underwater acoustic communication method fields, and in particular to a kind of Adaptive Modulation based on channel estimating with The OFDM underwater acoustic communication method of power distribution.
Background technique
The problems such as there is the extensions of more ways in underwater acoustic channel seriously, band resource is limited, different hydrological environments, same environment Different moments, the corresponding underwater acoustic channel fading characteristic of different frequent points are not quite similar.Traditional multi-carrier OFDM underwater acoustic system is to every Sub-channels use identical messaging parameter, do not make full use of frequency spectrum resource.
Adaptive technique can preferably adapt to complicated underwater acoustic channel compared to traditional fixed communication mode and improve logical Believe efficiency, makes full use of band resource.However adaptive technique in field of underwater acoustic communication also in the stage of fumbling, mostly Self-adaptive underwater communication system selection fixed threshold method or mode switching manner sub-carrier or subband are modulated, and are needed in advance Water environment is measured, pattern switching threshold value is determined according to the ber curve of different communication mode, this is undoubtedly reduced adaptively Practicability of the technology for different water environments.
Adaptive technique needs to adjust configured transmission in real time according to channel state information, is influenced by propagation delay time, passes through biography The channel state information that the method for system channel estimation obtains can have out-of-date ask relative to the channel that will emit the data moment Topic, the performance degradation in varying Channels.
Summary of the invention
The purpose of the present invention is to provide a kind of self-adaptive underwater communication means.
A kind of self-adaptive underwater communication means, described method includes following steps:
(1) transmitting terminal sends test signal, and receiving end is handled signal is received, channel impulse response when estimation obtains Estimated result；
(2) time domain channel impulse response is predicted using adaptive channel prediction technique；
(3) prediction channel result is fed back into transmitting terminal by signalling, channel shape needed for obtaining Adaptive Transmission State information；
(4) transmitting terminal determines the messaging parameter of each subcarrier according to channel state information based on self-adjusted block algorithm, And adaptive modulation and power allocation is carried out according to messaging parameter sub-carrier；
(5) transmitting terminal transmitting OFDM signal realizes self-adaptive underwater communication.
In the step (1), transmitting terminal sends ofdm communication signal, and receiving end docking is decoded by signal, when obtaining multiple The time domain channel data at quarter are as follows:
In formula, l=0,1 ..., K-1, K are channel length, and p is prediction order,For the channel at m-p moment Estimated value,For the channel estimation value at m moment,For the time domain channel data at m moment.
In l time tap, channel estimating is successively carried out with p channel sample value of current and past, by adaptive Channel prediction arithmetic is answered to obtain optimum prediction coefficient w [m；L], the channel impulse response of future time instance is obtained, channel estimating is more Newly equation is
In formula, w [m；L] it is predictive coefficient vector, wH[m；L] it is w [m；L] conjugate transposition vector,For m+1 The channel estimating value at moment.
In the step (3), transmitting terminal will predict that channel is transformed into frequency domain by discrete Fourier transform, obtain adaptive Channel state information needed for system.
In the step (4), self-adjusted block algorithm is realized in certain traffic rate btargetWith transmission power PTUnder, make The target that the bit error rate performance of system is optimal, Optimality Criteria used in system indicate are as follows:
min BER
In formula, BER is wrong code rate, bkFor the bit number distributed in k-th of subchannel, PkFor point in k-th of subchannel With power.
The beneficial effects of the present invention are:
Channel estimating is carried out in the time domain, is improved precision of prediction while reducing feedback redundancy, is provided for Adaptable System Relatively reliable channel state information；Bit and power allocation is carried out using self-adjusted block algorithm sub-carrier, eliminates biography System self-adaptive underwater communication system measures water environment in advance and mould is artificially arranged according to the ber curve of different communication mode The step of formula handoff threshold, directly can carry out adaptive parameter selection according to the channel state information of feedback, improve strange Practicability under environment.
Detailed description of the invention
Fig. 1 is invention flow chart.
Fig. 2 is recursive least squares to the prediction result figure for surveying channel data under Arctic pack.
Fig. 3 is the self-adaptive underwater communication system ber curve figure respectively in the case where surveying and predicting channel.
Specific embodiment
This method is described in further detail in conjunction with attached drawing.
The present invention is directed to the high quality communication problem under time- variant channel, proposes there is the adaptive of channel estimating function Modulation and power distribution OFDM underwater acoustic communication method.OFDM technology is combined with adaptive technique can effectively antagonize channel frequency Selective intensity, and make full use of channel resource.To guarantee reliable communication of the adaptive technique in time varying channel, time domain into Row channel estimating obtains the channel state information of next emission time with this.Self-adjusted block algorithm sub-carrier is used simultaneously Bit and power allocation is carried out, underwater acoustic system performance is obviously improved and makes it using more flexible.
The present invention is further described below:
Embodiment one, the specific implementation of self-adaptive underwater communication means.
The adaptive modulation and power allocation method based on channel estimating in 1 couple of present invention carries out detailed with reference to the accompanying drawing It describes in detail bright.
Firstly, transmitting terminal sends ofdm communication signal, receiving end obtains the time domain letter at multiple moment to signal decoding is received Track data is
In formula, l=0,1 ..., K-1, K are channel length, and p is prediction order,For the channel at m-p moment Estimated value.Then in l time tap, channel estimating is successively carried out with p channel sample value of current and past, by certainly Adaptive channel prediction algorithm obtains optimum prediction coefficient w [m；L], the channel impulse response of future time instance is obtained, channel estimating Renewal equation is
In formula, w [m；L] it is predictive coefficient vector.
By taking recursive least squares as an example, table 1 is the specific implementation flow of adaptive channel prediction technique.
Table 1
Notify transmitting terminal, transmitting terminal that will predict that channel turns by discrete Fourier transform by signalling prediction result Frequency domain is changed to, channel state information needed for obtaining Adaptable System.
Then transmitting terminal is the suitable modulation system of each sub-carrier selection, distribution transmission function according to channel state information Rate.It is realized by self-adjusted block algorithm in certain traffic rate btargetWith transmission power PTUnder, make the bit error rate of system (BER) target that performance is optimal, therefore Optimality Criteria used in system can be expressed as
min BER
In formula, bkFor the bit number distributed in k-th of subchannel, PkFor corresponding distribution power.
Adaptive Modulation finally is carried out to information source information to send again with after power distribution, realizes self-adaptive underwater communication.
By taking Fischer algorithm as an example, table 2 is the detailed process of self-adapting distribution method.
Table 2
Embodiment two, simulation study.
Simulated conditions: what channel estimating utilized is the time- variant channel number obtained in arctic ice formation on the 12nd of August in 2018 According to.Prediction order p=1, forgetting factor λ=0.9, balance factor δ=0.99.It is 300 that channel data is surveyed under known Arctic pack Group.The channel at the 300th moment obtained using preceding 299 groups of channel estimatings is as shown in Fig. 2.
The modulation system used in emulation is BPSK, QPSK, 8QAM and 16QAM, sample frequency 48kHz, and subcarrier is total Number is 342, subcarrier spacing 11.7Hz, and OFDM symbol length is 256ms, and wherein circulating prefix-length is 64ms, FFT points It is 4096, it is 1:1 that Block-type pilot, which is inserted into ratio, sends 30 OFDM data blocks every time, and channel estimation mode is least square Method.
Attached drawing 3 is self-adaptive underwater communication system ber curve figure of the present invention respectively in the case where surveying and predicting channel. Curve 1 indicates that emulation channel used is the channel at the 300th moment of actual measurement, and modulation system used in system is QPSK modulation；It is bent Line 2 indicates that simulated channel is the channel at the 300th moment of prediction, and system is based on Fischer algorithm and carries out self-adjusted block；It is bent Line 3 indicates that simulated channel is the channel at the 300th moment of actual measurement, and system is based on Fischer algorithm and carries out self-adjusted block.It can To find out, the error rate of system performance based on adaptive algorithm is substantially better than traditional QPSK modulation, it was demonstrated that the invention is to water The improvement of sound communication system performance.Curve 2 and curve 3 in comparison diagram, it can be seen that the trend of two curves is almost the same.Card Sparse underwater acoustic channel can be effectively predicted in bright the invention, can provide reliably for the Adaptive Transmission in time-varying environment Channel state information.
In conclusion the present invention is to provide a kind of self-adaptive underwater communication means.The invention belongs to field of underwater acoustic communication. It is related to orthogonal frequency division multiplexing (OFDM) underwater acoustic communication method of a kind of Adaptive Modulation based on channel estimating and power distribution. (1) transmitting terminal sends test signal first, and receiving end is handled signal is received, and estimation obtains time domain channel impulse response； (2) time domain channel impulse response is predicted using adaptive channel prediction technique；(3) prediction channel result is passed through into signaling Transmission feeds back to transmitting terminal, channel state information needed for obtaining Adaptive Transmission；(4) transmitting terminal is according to channel state information base The messaging parameter of each subcarrier is determined in self-adjusted block algorithm, and Adaptive Modulation is carried out according to messaging parameter sub-carrier And power distribution；(5) transmitting terminal transmitting OFDM signal realizes self-adaptive underwater communication.The advantage of the invention is that (1) is in time domain Upper carry out channel estimating improves precision of prediction while reducing feedback redundancy, relatively reliable channel is provided for Adaptable System Status information；(2) bit and power allocation is carried out using self-adjusted block algorithm sub-carrier, eliminates traditional self-adaptive underwater Communication system measures water environment and in advance according to the artificial Setting pattern handoff threshold of the ber curve of different communication mode Step directly can carry out adaptive parameter selection according to the channel state information of feedback, improve practical under foreign environment Property.

Claims (5)

1. a kind of self-adaptive underwater communication means, it is characterized in that: described method includes following steps:
(1) transmitting terminal sends test signal, and receiving end is handled signal is received, channel impulse response estimation when estimation obtains As a result；
(2) time domain channel impulse response is predicted using adaptive channel prediction technique；
(3) prediction channel result is fed back into transmitting terminal by signalling, channel status needed for obtaining Adaptive Transmission is believed Breath；
(4) transmitting terminal determines the messaging parameter of each subcarrier, and root according to channel state information based on self-adjusted block algorithm Adaptive modulation and power allocation is carried out according to messaging parameter sub-carrier；
(5) transmitting terminal transmitting OFDM signal realizes self-adaptive underwater communication.
2. a kind of self-adaptive underwater communication means according to claim 1, it is characterized in that: in the step (1), transmitting terminal Ofdm communication signal is sent, receiving end docking is decoded by signal, obtains the time domain channel data at multiple moment are as follows:
In formula, l=0,1 ..., K-1, K are channel length, and p is prediction order,For the channel estimation at m-p moment Value,For the channel estimation value at m moment,For the time domain channel data at m moment.
3. a kind of self-adaptive underwater communication means according to claim 2, it is characterized in that: in l time tap, with working as Preceding and past p channel sample value successively carries out channel estimating, obtains optimum prediction system by adaptive channel prediction algorithm Number w [m；L], the channel impulse response of future time instance is obtained, the renewal equation of channel estimating is
In formula, w [m；L] it is predictive coefficient vector, wH[m；L] it is w [m；L] conjugate transposition vector,For the m+1 moment Channel estimating value.
4. a kind of self-adaptive underwater communication means according to claim 1, it is characterized in that: in the step (3), transmitting terminal It will predict that channel is transformed into frequency domain by discrete Fourier transform, channel state information needed for obtaining Adaptable System.
5. a kind of self-adaptive underwater communication means according to claim 1, it is characterized in that: in the step (4), adaptively Allocation algorithm is realized in certain traffic rate btargetWith transmission power PTUnder, the mesh that is optimal the bit error rate performance of system It marks, Optimality Criteria used in system indicates are as follows:
min BER
In formula, BER is wrong code rate, bkFor the bit number distributed in k-th of subchannel, PkFor the distribution function in k-th of subchannel Rate.
CN201910590940.3A 2019-07-02 2019-07-02 A kind of self-adaptive underwater communication means Pending CN110351209A (en)

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Application publication date: 20191018