CN107124213A - Based on directly adaptive two-way turbo equalization methods in mimo systems - Google Patents
Based on directly adaptive two-way turbo equalization methods in mimo systems Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
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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
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
- H04B7/0417—Feedback systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
- H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
- H04B7/0842—Weighted combining
- H04B7/0845—Weighted combining per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch
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Abstract
The present invention relates in a kind of mimo systems based on directly adaptive two-way turbo equalization methods, this method is applied in two-way soft decision feedback balanced device, and two-way soft decision feedback balanced device includes a conventional soft decision feedback balanced device, a soft decision feedback balanced device with time reversal；Soft decision feedback balanced device with time reversal respectively connects one in the input and output end of conventional soft decision feedback balanced device can realize the part of time reversal operation；This method includes：In two-way soft decision feedback balanced device, two-way turbo is using the feedback signal of received signal and received signal balanced, by preceding to turbo result and backward turbo result linear, additives in a balanced way in a balanced way, realize the estimation of signal.Method stability of the invention is strong, accuracy of detection is high, algorithmic statement is fast, complexity is low, has certain practical value and application prospect in actual underwater sound communication system.
Description
Technical field
The present invention relates to field of underwater acoustic communication, based on directly adaptive double in more particularly to a kind of mimo systems
To turbo equalization methods.
Background technology
Due to underwater acoustic channel Bandwidth-Constrained, single-input single-output (SISO, simple input simple output) system is difficult
Practical communication demand is met, studies more for multiple-input, multiple-output (MIMO, Multiple-Input now
Multiple-Output) system.In mimo system, transmitting terminal is launched using many array elements, improves traffic rate, and
Receiving terminal is received using many array elements, obtains diversity gain.For SISO systems, except depositing in mimo system
Outside intersymbol interference and error propagation phenomenon, also there are problems that the co-channel interference between multichannel transmitting, these problems
All limit the practical application of mimo system.
For co-channel interference, in bibliography 1《A.Song,M.Badiey,V.K.McDonald,and T.C.Yang,
“Time reversal receivers for high data rate acoustic multiple-input-multiple-output
communication,”IEEE J.Ocean.Eng.,vol.36,no.4,pp.525-538,Oct.2011》In, Song
Et al. propose use time reversal technology, designed using the time reversal form of the channel impulse response estimated
Wave filter, realizes signal focus, and plus technologies such as parallel interference canceller and serial interference eliminations, recover original
Signal.In addition, in bibliography 2《M.T.Tuchler,R.Koetter,and A.C.Singer,“Turbo
equalization:Principles and newresults,”IEEE Trans.Commun.,vol.50,no.5,pp.
754-767,May2002》In, Tuchler et al. proposes the judgement based on least mean-square error under mimo system
Feedback equalizer (MMSE-DFE), signal decorivolution is realized using the channel impulse response estimated.
For the error propagation phenomenon in DFE, in bibliography 3《W.Duan and Y.R.Zheng,
“Bidirectional soft-decision feedback turbo equalization for MIMO systems,”IEEE Trans.
Veh.Technology,pp.1-11,Aug.2015》In, Duan et al. proposes the thought of bidirectional equalization, using by mistake
Difference propagate randomness and it is front and rear to equilibrium result correlation it is extremely low the characteristics of, the output result of bidirectional equalization is linear
It is added, obtains diversity gain.In addition, in order to lift mimo system equalization performance, by two-way DFE and turbo
Equilibrium is combined, and reduce further the bit error rate.
For the demand of underwater acoustic channel environment and high-speed underwater sound communication complicated and changeable, in above-mentioned existing mimo system
The shortcoming of equalization scheme is primarily present in the following aspects：
1st, the balanced device in existing mimo system is required for channel estimation, is either also based on based on time reversal
MMSE-DFE, channel estimation method is directed to multiplication and the inversion operation of large scale matrix, and computation complexity is too high,
It is unfavorable for the real-time processing of data.
2nd, the turbo equalization methods in existing mimo system are too dependent on the degree of accuracy of channel estimation.For
Time reversal operates, if channel estimation is inaccurate to cause signal focus failure, it is impossible to obtain diversity gain；It is right
In the system based on MMSE-DFE, filter tap coefficients will be caused inaccurate if channel estimation is inaccurate,
So that balanced device and decoder failure.Moreover, in the underwater acoustic channel environment of time-varying, training sequence is estimated
The channel impulse response come is difficult the channel impulse response for characterizing valid data, and this causes existing equalization methods stability
It is not high.
3rd, the number of mimo system median filter is more than SISO system, and this can increase the computation complexity of algorithm,
Existing turbo equalization methods do not utilize the openness of underwater acoustic channel impulse response, also lack effective quick adaptive
Algorithm is answered, this causes, and the redundancy of signal transacting is excessive, restrained slow, influence the real-time processing of data.
The content of the invention
It is an object of the invention to overcome the defect of equalization methods in existing mimo system, so as to provide a kind of detection
The method that precision is high, stability is high.
To achieve these goals, the invention provides in a kind of mimo systems based on directly adaptive two-way
Turbo equalization methods, this method is applied in two-way soft decision feedback balanced device, and the two-way soft decision feedback is balanced
Device includes a conventional soft decision feedback balanced device, a soft decision feedback balanced device with time reversal；The band time
The soft decision feedback balanced device of reversion respectively connects an energy in the input and output end of conventional soft decision feedback balanced device
Realize the part of time reversal operation；This method includes：
In two-way soft decision feedback balanced device, done using the feedback signal of received signal and received signal
Two-way turbo is balanced, by preceding to turbo result and backward turbo result linear, additives in a balanced way in a balanced way, realizes letter
Number estimation.
In above-mentioned technical proposal, this method further comprises：
Step 1), in transmitting terminal original signal sequence is divided into N roads, all placed training sequence end to end per road signal
Row；Wherein, training sequence of the training sequence known to one group of receiving terminal between data, each road signal is mutual not
It is related；
Step 2), any array element in receiving terminal receive after the signal for including training sequence that transmitting terminal is launched,
Received signal is inputted into two-way soft decision feedback balanced device；
Step 3), in the soft decision feedback balanced device with time reversal, time reversal behaviour is to received signal
Make, the signal after time reversal is then copied into N roads；In conventional soft decision feedback balanced device, it will directly be connect
The signal of receipts copies into N roads；
Step 4), the soft decision feedback balanced device with time reversal with conventional soft decision feedback balanced device, equal profits
Filter coefficient is adjusted with the corresponding training sequence in the N roads signal obtained by copy, the transmission signal on other roads is considered as
0dB noise；
Step 5), each road signal for being received to receiving terminal each array element sums；
Step 6), that the N roads signal obtained by after summation and the feedback signal obtained by preceding an iteration are done into judgement is anti-
Feedback is balanced；Wherein, in first time decision feedback equalization, feedback signal is 0；
Step 7), demapping, parallel-serial conversion are taken turns doing to the sequence after decision feedback equalization, with time reversal
Also need to do time reversal operation to the result after parallel-serial conversion in soft decision feedback balanced device, then output result；
Then directly the result after parallel-serial conversion is exported in conventional soft decision feedback balanced device；
Step 8), by the output of the soft decision feedback balanced device with time reversal and conventional soft decision feedback balanced device
Two-way joint is done in output, and deinterleaving, decoding are then taken turns doing to two-way united result；
Step 9), judge whether two-way soft decision feedback balanced device restrains, if not converged, perform next step, it is no
Then, decoding result output；
Step 10), decoding result is done and interweaved, then respectively the soft decision feedback balanced device of input tape time reversal,
Conventional soft decision feedback balanced device；Wherein, also needed to before the soft decision feedback balanced device of input tape time reversal pair
Intertexture result does time reversal operation；
Step 11), the soft decision feedback balanced device to input tape time reversal, the letter of conventional soft decision feedback balanced device
Number serioparallel exchange is done respectively, N roads are then divided into again, obtain the correspondence training in feedback signal, the feedback signal
Sequence is used to adjust filter coefficient, then performs step 6).
It is further comprising the steps of after first time decision feedback equalization in above-mentioned technical proposal：
The filter coefficient in two-way soft decision feedback balanced device is obtained, one is set according to the average energy of these coefficients
Individual thresholding, deletes the filter coefficient less than this thresholding, remains larger than the coefficient of this thresholding, and record this
The position of a little coefficients.
In above-mentioned technical proposal, in step 4) and step 11) in, using the steepest of embedded digital phase-locked loop from excellent
Change algorithm to adjust filter coefficient.
In above-mentioned technical proposal, in step 9) in, judge two-way soft decision feedback balanced device whether restrain including：Sentence
Disconnected bit error rate with before than whether reducing, if bit error rate is no longer reduced, two-way soft decision feedback balanced device receipts
Hold back, be not restrain otherwise.
The advantage of the invention is that：
1st, the present invention propose a kind of mimo system based on directly adaptive two-way turbo equalization methods, should
Equalization methods are without channel estimation, and the Soft Inform ation returned using turbo equalized feedbacks realizes that co-channel interference is eliminated, it is to avoid
The multiplication of big dimensional matrix and inversion operation, substantially reduce algorithm complex, improve efficiency of algorithm, and
The balanced device that this method is used is based on Direct adaptive algorithm, is difficult to be influenceed by time varying channel, algorithm stability
It is high.
2nd, on the basis of SISO systems, the present invention expands two-way SDFE (soft decision feedback balanced device) structure
Arrived in mimo system, using the randomness of error propagation, by two SDFE output result linearly plus and,
Error propagation effectively is inhibited, accuracy of detection is improved, reduces bit error rate.
3rd, in the methods of the invention, the adjustment of equalizer coefficients employs Sparse Least, solves mimo system
The problem of amount of calculation is excessive, in addition, the adjustment of equalizer coefficients employs embedded DPLL FOLMS algorithms, makes
The iteration step length in algorithm is obtained as error is adaptively adjusted, and accuracy of detection and efficiency of algorithm has been obtained further
Lifting.
4th, in mimo system proposed by the present invention based on directly adaptive two-way turbo equalization methods stability it is strong,
Accuracy of detection is high, algorithmic statement is fast, complexity is low, have in actual underwater sound communication system certain practical value and
Application prospect.
Brief description of the drawings
Fig. 1 is the flow chart based on directly adaptive two-way turbo equalization methods of the present invention；
Fig. 2 (a)-Fig. 2 (f) be by one, three, five times it is repeatedly balanced after and decoding after planisphere；
Fig. 3 is unidirectional balanced (DA-TEQ) and bidirectional equalization (DA-BTEQ) under the conditions of different reception element number of array
EXIT comparison diagrams.
Embodiment
In conjunction with accompanying drawing, the invention will be further described.
Problem is described
In mimo systems, it is assumed that transmitting element number of array is N, reception element number of array is M, and underwater acoustic channel is modeled as
Limited channel impulse response, noise is the reception of additive white Gaussian noise (AWGN), then m-th of array element of kth moment
Signal rm,kFor：
Wherein, sn,kFor the transmission signal of n-th of array element of kth moment, hn,m,l-kFor n-th of transmitting array element of l-k moment
And m-th of channel impulse response received between array element, vm,kFor the Gauss being superimposed in m-th of reception array element of kth moment
White noise.
From (1), formula can be seen that in mimo systems, if it is desired to telling each transmitting letter from signal is received
Number, in addition to intersymbol interference to be eliminated (second summation expression formula in formula (1) embodies intersymbol interference),
Also need to eliminate co-channel interference (first summation expression formula in formula (1) embodies co-channel interference).In addition, water
The impulse response of Acoustic channel may continue tens or symbol lengths up to a hundred, and this undoubtedly adds computation complexity.
Being needed based on directly adaptive two-way turbo equalization methods when realizing for the present invention is anti-using two-way soft-decision
Balanced device (BiSDFE) is presented, the two-way soft decision feedback balanced device includes two soft decision feedback balanced devices (SDFE),
One of soft decision feedback balanced device is soft decision feedback balanced device of the prior art, another soft decision feedback
Balanced device is the soft decision feedback balanced device with time reversal.The soft decision feedback balanced device of the band time reversal with
Soft decision feedback balanced device of the prior art is identical on the body construction, is simply respectively needed in input and output end
One can realize the part of time reversal operation.
It is of the invention to be included based on directly adaptive two-way turbo equalization methods with reference to Fig. 1：
Step 1), in transmitting terminal original signal sequence is divided into N roads, all placed training sequence end to end per road signal
Row；Wherein, training sequence of the training sequence known to one group of receiving terminal between data, each road signal is mutual not
Correlation, distinguishes each road signal on this basis；
Step 2), any array element in receiving terminal receive after the signal for including training sequence that transmitting terminal is launched,
Received signal is inputted into two-way soft decision feedback balanced device, i.e., received signal is inputted respectively and conventional soft sentenced
Certainly feedback equalizer, the soft decision feedback balanced device with time reversal；
Step 3), in the soft decision feedback balanced device with time reversal, time reversal behaviour is to received signal
Make, the signal after time reversal is then copied into N roads；In conventional soft decision feedback balanced device, it will directly be connect
The signal of receipts copies into N roads；
Wherein, time reversal operation just refers to the order for exchanging sequence, such as sequence [1 23456 7] by when
Between reverse turn operation be changed into [7 65432 1]；
Step 4), the soft decision feedback balanced device with time reversal with conventional soft decision feedback balanced device, equal profits
With the corresponding training sequence adjustment filter coefficient (f, f as shown in Figure 1 ') in the N roads signal obtained by copy,
To eliminate intersymbol interference, the transmission signal on other roads regards 0dB noise as；
Wherein, in this step, because the intensity of 0dB noises is too big, therefore portfolio effect now will not be very good,
Need the loop iteration in subsequent step；
Step 5), each road signal for being received to receiving terminal each array element sum, due to before every road signal by
N roads are copied into, therefore in the soft decision feedback balanced device with time reversal or conventional soft decision feedback balanced device, are asked
There are N roads with rear resulting result；
Step 6), that the N roads signal obtained by after summation and the feedback signal obtained by preceding an iteration are done into judgement is anti-
Feedback is balanced；Wherein, when iterating to calculate first time, feedback signal is 0；
Step 7), solution is taken turns doing to the sequence (including training sequence and actual information sequence) after decision feedback equalization
Mapping, parallel-serial conversion, are also needed to the result after parallel-serial conversion in the soft decision feedback balanced device with time reversal
Time reversal operation is done, then output result；In conventional soft decision feedback balanced device then directly by parallel-serial conversion after
Result output；
Step 8), by the output of the soft decision feedback balanced device with time reversal and conventional soft decision feedback balanced device
Two-way joint is done in output, and deinterleaving, decoding are then taken turns doing to two-way united result；
Step 9), judge whether two-way soft decision feedback balanced device restrains, if not converged, perform next step, it is no
Then, decoding result output；
In this step, judge two-way soft decision feedback balanced device whether restrain including：Judge bit error rate with comparing before
Whether reduce, if bit error rate is no longer reduced, otherwise two-way soft decision feedback equalizer convergence, is not receive
Hold back；
Step 10), decoding result is done and interweaved, then respectively the soft decision feedback balanced device of input tape time reversal,
Conventional soft decision feedback balanced device；Wherein, also needed to before the soft decision feedback balanced device of input tape time reversal pair
Intertexture result does time reversal operation；
Step 11), the soft decision feedback balanced device to input tape time reversal, the letter of conventional soft decision feedback balanced device
Number serioparallel exchange is done respectively, N roads are then divided into again, obtain the correspondence training in feedback signal, the feedback signal
Sequence is used to adjust filter coefficient (b in such as Fig. 1, b '), and then the feedback signal can further apply step
It is rapid 6) in decision feedback equalization operation in.
Above is a kind of implementation based on directly adaptive two-way turbo equalization methods of the present invention.Another
In individual embodiment, as a kind of preferred implementation, also include using coefficient Sparse Least and calculate multiple to reduce
It is miscellaneous the step of spend.
Due to being communicated in the present invention using mimo system, the number of filter in balanced device is SISO systems
N × M times of system, this can undoubtedly increase amount of calculation, so as to influence the real-time processing of signal.Therefore, in the present invention
Employ coefficient Sparse Least to reduce computation complexity, arthmetic statement is as follows：After balanced by first time,
The coefficient of device median filter can be equalized, a thresholding is set according to the average energy of these coefficients, is deleted small
In the coefficient of this thresholding, the coefficient of this thresholding is remained larger than, and records the position of these coefficients.
Little is influenceed on final result after very little, therefore deletion are contributed filter result due to less coefficient,
We only need to adjust these coefficients retained in iterative process afterwards, and computation complexity is reduced with this.
In another embodiment, in the step 4 of the inventive method) and step 11) in, additionally use embedded number
The steepest self-optimizing algorithm (FOLMS) of word phaselocked loop (DPLL) adjusts filter coefficient so that of the invention
Method Fast Convergent.
Above is the description of the method to the present invention.From the inventive method the step of description in as can be seen that the present invention
Method eliminate intersymbol interference and co-channel interference using the signal fed back.In view of the balanced phases of SDFE and turbo
With reference to that can bring the defect of error propagation, method of the invention also eliminates error biography using the diversity of bidirectional equalization
Broadcast.Because mistake occurs in error propagation position in having randomness, forward direction balanced is differed in reverse equilibrium
Surely occur, therefore error propagation can be effectively eliminated to balanced and reverse result linear, additive in a balanced way by preceding.
Performance evaluation
For the validity of verification algorithm, the applicant has carried out lake examination experiment.Experimental period is 11 in 2015
Month, place is Thousand-Island Lake.Communicated using 2 × 4 mimo system, transmitting transducer and receive transducer are equal
It is positioned at 15m under water, 1m, communication distance 2000m is spaced between each transducer.Transmission signal uses QPSK
Modulation, RSC codings, the generator polynomial of encoder is [5,7], signal center frequency 12KHz, transducer bandwidth
9~15KHz, sample rate 96KHz, the character rate 6KHz of single array element transmission, the character rate of double array elements transmission is
12KHz.Transmission signal is synchronized using Hyperbolic Frequency Modulation signal, and protection interval is 2048 sampled points, training symbol
Number number is 200, and information symbol number is 1936.We employ two-way turbo equalization algorithms and carry out signal detection,
And give planisphere and external information transfer figure (EXIT).
Fig. 2 (a)-Fig. 2 (f) gives by one, three, five times it is repeatedly balanced after and decoding after planisphere.Such as
Shown in figure, the planisphere after five iteration equalizings is not substantially converged, and bit error rate is only 0.0102, increase
Iterations can not further reduce bit error rate, and the planisphere after decoding substantially has converged to four quadrants,
Bit error rate is 0.This explanation is using the two-way turbo methods in mimo system proposed by the present invention in 2000m
It can realize that zero error code is transmitted under channel.In order to which method proposed by the present invention and other method of the prior art are entered
Row contrast, applicant gives unidirectional balanced (DA-TEQ) and bidirectional equalization under the conditions of different reception element number of array
(DA-BTEQ) EXIT figure contrasts.As shown in figure 3, receiving, element number of array is more, and EXIT curves are transmitted
It is more remote, also imply that lower bit error rate.It is balanced for 2 × 4 unidirectional turbo, it is outer during final convergence
Information is 0.84, and external information during two-way turbo equilibrium convergences is 1, and this explanation bidirectional equalization performance is more excellent.
Under the conditions of the reception array element of other numbers, the performance of bidirectional equalization is superior to unidirectional equilibrium, in the unidirectional equilibrium of this explanation
Error propagation is there may be, so that balanced device fails, and bidirectional equalization can effectively eliminate error propagation, drop
Low bit error rate.In summary, two-way turbo equalization methods proposed by the present invention successfully inhibit error propagation, obtain
The diversity gain that many array elements are received was obtained, signal detection can be effectively realized.
It should be noted last that, the above embodiments are merely illustrative of the technical solutions of the present invention and it is unrestricted.Although
The present invention is described in detail with reference to embodiment, it will be understood by those within the art that, to the present invention
Technical scheme modify or equivalent substitution, without departure from the spirit and scope of technical solution of the present invention, its is equal
It should cover among scope of the presently claimed invention.
Claims (5)
1. based on directly adaptive two-way turbo equalization methods in a kind of mimo systems, this method is applied to
In two-way soft decision feedback balanced device, it is balanced that the two-way soft decision feedback balanced device includes a conventional soft decision feedback
The soft decision feedback balanced device of device, one with time reversal；The soft decision feedback balanced device of the band time reversal is normal
The part of time reversal operation can be realized by advising each connection one of input and output end of soft decision feedback balanced device；Should
Method includes：
In two-way soft decision feedback balanced device, done using the feedback signal of received signal and received signal
Two-way turbo is balanced, by preceding to turbo result and backward turbo result linear, additives in a balanced way in a balanced way, realizes letter
Number estimation.
2. based on directly adaptive two-way turbo equilibrium sides in mimo systems according to claim 1
Method, it is characterised in that this method further comprises：
Step 1), in transmitting terminal original signal sequence is divided into N roads, all placed training sequence end to end per road signal
Row；Wherein, training sequence of the training sequence known to one group of receiving terminal between data, each road signal is mutual not
It is related；
Step 2), any array element in receiving terminal receive after the signal for including training sequence that transmitting terminal is launched,
Received signal is inputted into two-way soft decision feedback balanced device；
Step 3), in the soft decision feedback balanced device with time reversal, time reversal behaviour is to received signal
Make, the signal after time reversal is then copied into N roads；In conventional soft decision feedback balanced device, it will directly be connect
The signal of receipts copies into N roads；
Step 4), the soft decision feedback balanced device with time reversal with conventional soft decision feedback balanced device, equal profits
Filter coefficient is adjusted with the corresponding training sequence in the N roads signal obtained by copy, the transmission signal on other roads is considered as
0dB noise；
Step 5), each road signal for being received to receiving terminal each array element sums；
Step 6), that the N roads signal obtained by after summation and the feedback signal obtained by preceding an iteration are done into judgement is anti-
Feedback is balanced；Wherein, in first time decision feedback equalization, feedback signal is 0；
Step 7), demapping, parallel-serial conversion are taken turns doing to the sequence after decision feedback equalization, with time reversal
Also need to do time reversal operation to the result after parallel-serial conversion in soft decision feedback balanced device, then output result；
Then directly the result after parallel-serial conversion is exported in conventional soft decision feedback balanced device；
Step 8), by the output of the soft decision feedback balanced device with time reversal and conventional soft decision feedback balanced device
Two-way joint is done in output, and deinterleaving, decoding are then taken turns doing to two-way united result；
Step 9), judge whether two-way soft decision feedback balanced device restrains, if not converged, perform next step, it is no
Then, decoding result output；
Step 10), decoding result is done and interweaved, then respectively the soft decision feedback balanced device of input tape time reversal,
Conventional soft decision feedback balanced device；Wherein, also needed to before the soft decision feedback balanced device of input tape time reversal pair
Intertexture result does time reversal operation；
Step 11), the soft decision feedback balanced device to input tape time reversal, the letter of conventional soft decision feedback balanced device
Number serioparallel exchange is done respectively, N roads are then divided into again, obtain the correspondence training in feedback signal, the feedback signal
Sequence is used to adjust filter coefficient, then performs step 6).
3. based on directly adaptive two-way turbo equilibrium sides in mimo systems according to claim 2
Method, it is characterised in that further comprising the steps of after first time decision feedback equalization：
The filter coefficient in two-way soft decision feedback balanced device is obtained, one is set according to the average energy of these coefficients
Individual thresholding, deletes the filter coefficient less than this thresholding, remains larger than the coefficient of this thresholding, and record this
The position of a little coefficients.
4. it is equal based on direct adaptive two-way turbo in the mimo systems according to Claims 2 or 3
Weighing apparatus method, it is characterised in that in step 4) and step 11) in, using the steepest of embedded digital phase-locked loop from excellent
Change algorithm to adjust filter coefficient.
5. based on directly adaptive two-way turbo in the mimo systems according to Claims 2 or 3 or 4
Equalization methods, it is characterised in that in step 9) in, judge two-way soft decision feedback balanced device whether restrain including：
Judge bit error rate with before than whether reducing, if bit error rate is no longer reduced, two-way soft decision feedback balanced device
Convergence, is not restrain otherwise.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109981501A (en) * | 2019-03-08 | 2019-07-05 | 哈尔滨工程大学 | A kind of direct adaptive MIMO communication means of the underwater sound |
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