CN107294650A - Coding method and device - Google Patents
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- CN107294650A CN107294650A CN201610221775.0A CN201610221775A CN107294650A CN 107294650 A CN107294650 A CN 107294650A CN 201610221775 A CN201610221775 A CN 201610221775A CN 107294650 A CN107294650 A CN 107294650A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
- H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
- H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
- H03M13/11—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits using multiple parity bits
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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
- H04L1/0056—Systems characterized by the type of code used
- H04L1/0057—Block codes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/06—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols the encryption apparatus using shift registers or memories for block-wise or stream coding, e.g. DES systems or RC4; Hash functions; Pseudorandom sequence generators
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Abstract
The invention provides a kind of coding method and device, methods described includes：According to check matrix H*Message to be sent in main channel is encoded, wherein, pass through the coefficient fading matrix diag (h of Rayleigh fading main channelb) and without decline when check matrix H determine the H*, the message to be sent includes：True messages skWith random message dl‑k；Send the message to be sent after being encoded.Using above-mentioned technical proposal, the problem of coding techniques can not meet information security in correlation technique is solved, and then has reached raising main channel security, tapping channel can not decode out the effect of the message truly sent.
Description
Technical field
The present invention relates to the communications field, in particular to a kind of coding method and device.
Background technology
The research origin of wireless communication system physical layer safety is in the famous papers on tapping channel of Wyner.At this
In paper, Wyner have studied the channel model that Point-to-Point Communication System is eavesdropped by a listener-in.Wyner is determined with conditional entropy
Adopted listener-in gives the maximum of the information transfer efficiency when the doubt degree of listener-in is maximum to the doubt degree of confidential information
Value, i.e. safe capacity.In the existence proof of safe capacity, Wyner proposes random vanning (random binning)
Coding techniques.In the channel model for considering safety, the technology has become a kind of most common coding techniques.Casing at random is
Refer to the message sent and a code book (set of a pile code word composition) corresponds.When sender sends a specific message
When, the code book corresponding with this message is found out first, and then randomly choosing a code word in this code book sends, the code
Word is just as the output of encoder.After the proposition of tapping channel model, construct reality can approach the code word of safe capacity just
Become one new research direction of coding field.Wyner is pointed out when tapping channel is Gaussian noise, the muting feelings of main channel
Under condition, using coset encoding scheme and subcode be any one up to the good code of tapping channel capacity dual code when, Ke Yida
Safety on to implication in information theory.Wyner to the research of tapping channel mainly for discrete memoryless and the situation of Gaussian noise,
Here it must be pointed out that above two noise situations and actual wireless channel have larger difference.Actual wireless channel is time-varying
The channel of decline, we generally simulate actual wireless channel with rayleigh fading channel.Research work based on Wyner,
Liang et al. have studied the safe capacity of Time-varying fading tapping channel model.In the existence proof of its safe capacity,
Liang et al. has equally used the coding techniques of random vanning, although there is also using Turbo code, Polar in correlation technique
Code, BCH code, the technical scheme of Reed-Solomon codes and concatenated code, but security is problematic in that.
For in correlation technique, the problem of coding techniques can not meet information security not yet proposes effective solution.
The content of the invention
The invention provides a kind of coding method and device, the problem of at least to solve in correlation technique.
According to an aspect of the invention, there is provided a kind of coding method, including：According to check matrix H*To in main channel
Message to be sent encoded, wherein, pass through the coefficient fading matrix diag (h of Rayleigh fading main channelb) and without decline when
Check matrix H determine the H*, the message to be sent includes：True messages skWith random message dl-k；Transmission is encoded
Message to be sent afterwards.
Preferably, according to fading coefficients matrix diag (hb) and default check matrix H generation check matrix H*, including：Pass through
Below equation obtains the check matrix H*：H*=diag (hb)H。
Preferably, the check matrix H*It is n+k bits for code word size, message-length is the low-density parity of l bits
The check matrix of checksum LDPC code, wherein, k<l<N+k, the skIncluding k bit, the dl-kIncluding l-k bit, lead to
Cross the check matrix H*Code word size after being encoded to the message to be sent is n+k bits, n, and k, l is just whole
Number.
Preferably, the n, k, l meet below equation：
Wherein, diag (he) be the corresponding Rayleigh fading tapping channel of the main channel coefficient fading matrix, SNR1,
SNR2The signal to noise ratio of respectively described main channel and the tapping channel, and SNR2Value be less than SNR1Value.
Preferably, methods described also includes：
The skWith the dl-kPass through the check matrix H*Code word r after codingn+k, wherein, rn+k=((sk,dl-k)·
BT·(A-1)T,sk,dl-k), H-matrix is turned to by AB type matrixes by Gaussian elimination method, A is unit matrix, unit matrix A row
Number and columns are n+k-l matrix, and B is that a line number is n+k-l, and columns is l matrix, H=diag-1(hb)H*, BTRepresent
The transposition of matrix B, (A-1)TThe transposition of representing matrix A inverse matrix.
Preferably, methods described also includes：The code word rn+kActual transmissions efficiency be less than main channel channel capacity.
According to another aspect of the present invention, a kind of code device is additionally provided, including：
Coding module, for according to check matrix H*Message to be sent in main channel is encoded, wherein, by auspicious
The coefficient fading matrix diag (h of profit decline main channelb) and without decline when check matrix H determine the H*, it is described to be sent to disappear
Breath includes：True messages skWith random message dl-k；
Sending module, for sending the message to be sent after being encoded.
Preferably, the coding module, for obtaining the check matrix H by below equation*：H*=diag (hb)H。
Preferably, the check matrix H that the coding module is obtained*It is n+k bits for code word size, message-length is
The check matrix of the low density parity check code LDPC code of l bits, wherein, k<l<N+k, the skIncluding k bit, the dl -kIncluding l-k bit, pass through the check matrix H*Code word size after being encoded to the message to be sent is n+k ratios
Spy, n, k, l is positive integer.
Preferably, the n, k, l meet below equation：
Wherein, diag (he) be the corresponding Rayleigh fading tapping channel of the main channel coefficient fading matrix, SNR1,
SNR2The signal to noise ratio of respectively described main channel and the tapping channel, and SNR2Value be less than SNR1Value.
By the present invention, using according to check matrix H*True messages and random message in message to be sent are compiled
The technical scheme of code, solves the problem of coding techniques can not meet information security in correlation technique, and then reached raising master
Channel safety, tapping channel can not decode out the effect of the message truly sent.
Brief description of the drawings
Accompanying drawing described herein is used for providing a further understanding of the present invention, constitutes the part of the application, this hair
Bright schematic description and description is used to explain the present invention, does not constitute inappropriate limitation of the present invention.In the accompanying drawings：
Fig. 1 is the flow chart of coding method according to embodiments of the present invention；
Fig. 2 is the structured flowchart of code device according to embodiments of the present invention；
Fig. 3 is the channel model applied according to the preferred embodiment of the present invention；
Fig. 4 is the encoder building method schematic diagram according to the preferred embodiment of the present invention；
Fig. 5 is according to the main channel of the preferred embodiment of the present invention and the ratio of tapping channel signal to noise ratio and listener-in's errored bit
A kind of relation schematic diagram between rate；
Fig. 6 is according to the main channel of the preferred embodiment of the present invention and the ratio of tapping channel signal to noise ratio and listener-in's errored bit
Another relation schematic diagram between rate；
Fig. 7 is according to the main channel of the preferred embodiment of the present invention and the ratio of tapping channel signal to noise ratio and listener-in's errored bit
Another relation schematic diagram between rate.
Embodiment
Describe the present invention in detail below with reference to accompanying drawing and in conjunction with the embodiments.It should be noted that not conflicting
In the case of, the feature in embodiment and embodiment in the application can be mutually combined.
It should be noted that term " first " in description and claims of this specification and above-mentioned accompanying drawing, "
Two " etc. be for distinguishing similar object, without for describing specific order or precedence.
A kind of coding method is provided in the present embodiment, and Fig. 1 is the flow of coding method according to embodiments of the present invention
Figure, as shown in figure 1, the flow comprises the following steps：
Step S102, according to check matrix H*Message to be sent in main channel is encoded, wherein, declined by Rayleigh
Fall the coefficient fading matrix diag (h of main channelb)Check matrix H during with without decline determines H*, message to be sent includes：Truly
Message skWith random message dl-k；
Step S104, sends the message to be sent after being encoded.
By each above-mentioned step, using according to check matrix H*To the true messages and random message in message to be sent
The technical scheme encoded, solves the problem of coding techniques can not meet information security in correlation technique, and then reach
Main channel security is improved, tapping channel can not decode out the effect of the message truly sent.
Preferably, according to fading coefficients matrix diag (hb) and default check matrix H generation check matrix H*, mainly pass through
Below equation obtains check matrix H*：H*=diag (hb) H, in an optional example, check matrix H*It is n+ for code word size
K bits, message-length is the check matrix of the low density parity check code LDPC code of l bits, wherein, k<l<N+k, skIncluding k
Individual bit, dl-kIncluding l-k bit, pass through check matrix H*Code word size after being encoded to message to be sent is n+k ratios
Spy, n, k, l is positive integer.
In one alternate embodiment, n, k, l meet below equation：
Wherein,
diag(he) be the corresponding Rayleigh fading tapping channel of main channel coefficient fading matrix, SNR1,SNR2Respectively main channel and steal
Listen the signal to noise ratio of channel, and SNR2Value be less than SNR1Value.
It should be noted that the actual transmissions efficiency of LDPC codeMore than the channel capacity of tapping channel, according to Shannon
Channel coding theorem, the decoding error probability of listener-in will not necessarily level off to 0.
For validated user, due to actual efficiency of transmissionLess than the channel capacity of main channel, according to Shannon
Channel coding theorem, when the signal to noise ratio of given channel, as long as the length long enough of LDPC code word, arbitrarily small (level off to 0)
Decoding error probability index can reach.For example, when the signal to noise ratio of main channel is 14, if requiring the decoding of validated user
Error probability is 10-8, then code word size n=280, message bit number k=20, the random bit l-k=80 present invention can be used
Secure coding method is realized in embodiment, total message bit l=5000000 × 100 that can be sent in emulation, decoding error
Bit number be 2 times, decoding error ratio be 4 × 10-9。
Because the channel capacity of tapping channel is equal toListener-in can utilize above-mentioned interpretation method from code word rnIn just
Random message bit l-k really is translated, here rn=(dL-k,[sk,dL-k]AT(B-1)T), even if it is noted here that rnStolen hearer obtains
Arrive, listener-in can not be from rnMiddle acquisition sk, because linear equation xAT(B-1)TThe number of=b solution is not unique, and is deposited
Much solving.According to the analysis in tapping channel model theory, translated if listener-in consumes its all decoding capability
Go out on random message bit k, then listener-in can not translate the true messages bit k of transmission completely.Simulation result shows, works as eavesdropping
When the signal to noise ratio of channel is larger, the ratio of error that listener-in translates true messages bit k approaches 0.5, the i.e. embodiment of the present invention and set
The safe coding and decoding method of meter is approached be perfectly safe (safety i.e. on implication in information theory).
Through the above description of the embodiments, those skilled in the art can be understood that according to above-mentioned implementation
The method of example can add the mode of required general hardware platform to realize by software, naturally it is also possible to by hardware, but a lot
In the case of the former be more preferably embodiment.Understood based on such, technical scheme is substantially in other words to existing
The part that technology contributes can be embodied in the form of software product, and the computer software product is stored in a storage
In medium (such as ROM/RAM, magnetic disc, CD), including some instructions are to cause a station terminal equipment (can be mobile phone, calculate
Machine, server, or network equipment etc.) perform method described in each of the invention embodiment.
A kind of code device is additionally provided in the present embodiment, and the device is used to realize above-described embodiment and the side of being preferable to carry out
Formula, had carried out repeating no more for explanation.As used below, term " module " can realize the software of predetermined function
And/or the combination of hardware.Although the device described by following examples is preferably realized with software, hardware, or soft
The realization of the combination of part and hardware is also that may and be contemplated.
Fig. 2 is the structured flowchart of code device according to embodiments of the present invention, as shown in Fig. 2 the device includes：
Coding module 20, for according to check matrix H*Message to be sent in main channel is encoded, wherein, pass through
The coefficient fading matrix diag (h of Rayleigh fading main channelb) and without decline when check matrix H determine H*, message package to be sent
Include：True messages skWith random message dl-k；
Sending module 22, for sending the message to be sent after being encoded.
By the comprehensive function of above-mentioned modules, using according to check matrix H*To the true messages in message to be sent
The technical scheme encoded with random message, solves the problem of coding techniques can not meet information security in correlation technique,
And then raising main channel security has been reached, tapping channel can not decode out the effect of the message truly sent.
Alternatively, coding module 20, for obtaining check matrix H by below equation*：H*=diag (hb) H, specifically,
The check matrix H that coding module 20 is obtained*It is n+k bits for code word size, message-length is the low-density checksum of l bits
The check matrix of code LDPC code, wherein, k<l<N+k, skIncluding k bit, dl-kIncluding l-k bit, pass through check matrix H*
Code word size after being encoded to message to be sent is n+k bits, n, and k, l is positive integer.
Preferably, n, k, l meet below equation：
Wherein, diag (he) be the corresponding Rayleigh fading tapping channel of main channel coefficient fading matrix, SNR1,SNR2Point
Not Wei main channel and tapping channel signal to noise ratio, and SNR2Value be less than SNR1Value.
It should be noted that above-mentioned modules can be by software or hardware to realize, for the latter, Ke Yitong
Cross in the following manner realization, but not limited to this：Above-mentioned module is respectively positioned in same processor；Or, above-mentioned module is located at many respectively
In individual processor.
The technical scheme of above-described embodiment is explained above in association with preferred embodiment, but be not used in restriction this hair
The technical scheme of bright embodiment.
The mathematical modeling of Rayleigh fading tapping channel can be expressed as
yn=diag (hb)xn+vb,zn=diag (he)xn+ve,
Here vbAnd veThe noise of validated user and listener-in's channel is represented respectively, and they are all that average is 0, variance difference
ForGaussian noise, and diag (hb),diag(he) it is channel fading coefficient matrix, and be following diagonal matrix,
Here hb,i,he,i(1≤i≤n) is multiple Gauss stochastic variable, and their variance is respectivelyBy the above
Definition is not difficult to learn | hb,i|,|he,i| Rayleigh fading distribution is obeyed, message to be sent is expressed as u, the generator matrix of coding
M is expressed as (it is noted here that M can be directly obtained by H, because MHT=0).By the code word x after codingn=Mu substitutes into Rayleigh and declined
Fall the mathematic(al) representation of channel：
yn=diag (hb)Mu+vb,zn=diag (he)Mu+ve,
Define M*=diag (hb) M, above-mentioned expression formula can be rewritten as
yn=M*u+vb,zn=diag (he)diag-1(hb)M*u+ve,
If above formula understands channel fading coefficient matrix diag (hb),diag(he) can all be obtained by sender and recipient
If, then it can utilize the generator matrix M and fading coefficients matrix diag (h during without declineb) given birth to produce a new coding
Into matrix M*=diag (hb)M.And from above formula, if still utilizing M*To be encoded, then the channel of validated user can be with
It is equivalent to a Gaussian channel.And the channel or fading channel of listener-in, only its fading coefficients become diag (he)
diag-1(hb).In summary, it is pre- when being carried out using fading coefficients matrix to the generator matrix of Gauss tapping channel encoding scheme
After processing, resulting newly-generated matrix can be for being used as the generation square of Rayleigh fading tapping channel secure coding schemes
Battle array.So, along the mentality of designing of Gauss tapping channel model based coding scheme, the peace with regard to Rayleigh fading tapping channel can be designed
Full coding and decoding scheme.
The design of the encoding scheme of the preferred embodiment of the present invention is as follows：
The theoretical foundation of safe coding and decoding conceptual design：In the existence proof of the safe coding theorem of tapping channel model
In, Wyner points out to design the coding and decoding scheme for reaching Information theoretical secure, it is necessary to using one kind be referred to as " random vanning "
Coding techniques.The chest that the coding techniques is constituted the message of transmitting and a pile code word is corresponded, and to be transmitted when given
During message, a random code word of being chosen from the code word chest corresponding to the message is sent.In order to allow listener-in can not
The message of transmission correctly is translated, it is necessary to consume the decoding capability of listener-in, and Wyner points out to assume that listener-in knows the specific of transmission
During message, if listener-in can be correctly found from the code word chest corresponding to the specific message (" translating ") transmission that with
During machine code word, then the decoding capability of listener-in is just consumed.If the code word chest corresponding to the specific message also seen
If being a kind of new code word, it is intended that the channel that the efficiency of transmission corresponding to the new code word is equal to tapping channel holds
Amount, because this whole decoding capability that represent listener-in is all consumed on the new code word is translated, so he is just without extra
It is in that ability goes to translate send actually for which message.The above-mentioned thought of safe coding theorem proving based on Wyner, it is assumed that
The message of transmission is k bits, and the length of code word is n-bit, then the secure coding schemes designed need to have three below feature：
(a) code can be divided into 2kIndividual subcode, the message bit of the k bit lengths of each subcode one transmission of correspondence；(b) reality of this yard
Efficiency of transmissionIt is less than the channel capacity C (SNR of main channel1), and the actual transmissions efficiency of subcode will be equal to the letter of tapping channel
Road capacity C (SNR2)；(c) the message bit k sent is given, random one code word hair of selection from the subcode corresponding to it
See off.
The parameter declaration of safe coding and decoding conceptual design：Assuming that the message sent is k bits, we are produced by random number
Raw device generates the random message of a l-k bit at random.In addition, it will be assumed that the length of code word is n+k bits.
The scheme of safe coding and decoding scheme can be achieved by the steps of：
It should be noted that following steps are not intended to limit the present invention the specific execution sequence of embodiment.
1) it is n+k bits to design a code word size according to the mentality of designing of classical LDPC code, and message-length is l bits
LDPC code check matrix, be designated as H*, the matrix has n+k-l rows, there is a n+k row, recycle fading coefficients matrix diag (hb)
A new check matrix H=diag is generated with existing H*-1(hb)H*。
2) the real transmission message of k bits and the random message of l-k bits are contained in the message of l bits.It is aobvious and easy
See, l meets following constraints k<l<n+k.
3) in order to realize coding methods of the Wyner described in the safe coding theorem proving of tapping channel model, i.e.,
When the k bit messages of transmission are determined, random chooses a this coded system of code word from its corresponding code word chest, I
Firstly the need of by above-mentioned designed check matrix be H, length for n+k bits LDPC code according to k bits true messages
It is divided into 2kIndividual subcode, the length of each subcode is n-bit.Such subcode is also a kind of linear block codes, and the subcode disappears
Breath bit is the random message of l-k bits.We realize in the following way " chooses a code word to pass from subcode at random
Send " coded system：(a) random message of a l-k bit is randomly generated by random number generator；(b) by the l-k bits
Random message one and its one-to-one code word are generated by the generator matrix of linear block codes, then this passes code word
Send.
The actual transmissions efficiency of above-mentioned subcode isCheck matrix is H, and code word size is n+k bits, and message-length is
The actual transmissions efficiency of the LDPC code of l bits isThe characteristics of in order to meet foregoing secure coding schemes (b), need
Make
After above-mentioned n, k, l restriction relation is given, check matrix is H, and code word size is n+k bits, and message is long
Spend as follows for the LDPC code design method of l bits：(a) turn to the check matrix H by Gaussian elimination method [A | B] type matrix,
It is noted here that H-matrix is n+k-l rows, and the matrix of n+k row, A matrixes are unit matrix, and its line number and columns are n+k-l.B squares
Battle array is that a line number is n+k-l, and columns is l matrix.As the given true messages s sentk, the message generated at random is dl-k
When, by the definition of check matrix, it can obtain：
(cn+k-l, sk,dl-k)HT=0, (formula 1)
Here cn+k-lThe check bit of n+k-l bits after presentation code.
H=[A | B] is substituted into (formula 1), can be obtained：
(formula 2) is arranged, can be obtained：
cn+k-l·AT+(sk,dl-k)·BT=0 (formula 3)
(formula 3) further is arranged, can be obtained：
cn+k-l=(sk,dl-k)·BT·(A-1)T(formula 4)
(formula 4), which gives to work as, knows true messages skThe message d generated at randoml-kWhen, calculate the check bit of code word
Formula.It is aware of after check bit, passes through code word r obtained from check matrix Hn+kIt is represented by
rn+k=(cn+k-l,sk,dl-k)=((sk,dl-k)·BT·(A-1)T,sk,dl-k) (formula 5)
For validated user, code word rn+kActual transmissions efficiencyThe channel capacity of main channel is less than,
So validated user can with level off to 0 decoding error probability while translating true messages skThe message d generated at randoml-k。
For listener-in, first it is desirable that he, which consumes its whole decoding capability, is correctly translating subcode rnOn, here
rn=(cn+k-l,sk,dl-k)=((sk,dl-k)·BT·(A-1)T,dl-k) (formula 6)
By rnAnd rn+kCompare, it is easy to find rnIt is by rn+kThe true messages s of middle transmissionkDelete, i.e. rnIt is rn+kSon
Code.For rnFor, message therein is dl-k, listener-in can correctly translate dl-k, and its whole decoding capability all consumes
Translate dl-kOn.Due to code word rn+kActual transmissions efficiency be greater than the channel capacity of tapping channel, from Shannon's theorems,
Listener-in translates rn+kError probability can not level off to 0.
Validated user and the decoder of listener-in use classic BP decoding algorithm, and the decoding algorithm is divided into following steps：
(1) prior probability first to rayleigh fading channel presupposed information bit；(2) passed by the informational probability of information node according to confidence
Broadcast the posterior probability that algorithm draws each check-node；(3) posteriority for extrapolating information node by the posterior probability of check-node is general
Rate；(4) the posterior probability control judgment condition of information node is made into hard decision, decodes and terminate if meeting；If it is not satisfied, then
(2)~(4) step more than repeating, iterates, until meeting condition, draws decoding result.If iterations reaches one
Individual default maximum times (such as 100), condition is still unsatisfactory for, then announces decoding failure；
Using rule (3,2) LDPC safety codes of BP decoding algorithms
First, Fig. 3 is the channel model applied according to the preferred embodiment of the present invention, as shown in figure 5, by regular (3,2)
LDPC safety codes (n=280, k=20, l=100) are used in rayleigh fading channel, observe its table in actual wireless channel
It is existing.Specifically, above-mentioned designed safe coding and decoding scheme is emulated in the environment of Rayleigh fading.Main channel is made to believe
Make an uproar than equal to 14, being compared with the situation of Gaussian noise, find the decoding error probability of validated user in the case of Rayleigh fading significantly
(decoding error probability of validated user is 4 × 10 in the case of Gaussian noise for increase-9, and validated user in the case of Rayleigh fading
0.0075) decoding error probability is.The decoding error probability and the letter of tapping channel of listener-in in the case of Rayleigh fading and Gauss
The relation made an uproar than between is shown in Fig. 4.It should be noted that the unit of our use standardization of Fig. 4 abscissa, that is, take 10 times with 10
It is bottom on main channel and the logarithmic function of tapping channel signal to noise ratio ratio.By Fig. 5, we are not difficult to find out, same coding staff
Anti- eavesdropping capability of the case under Rayleigh fading environment is significantly stronger than the anti-eavesdropping capability under Gaussian noise.
But as previously described, the correct decoding ability of validated user is weaker than under Gaussian environment under Rayleigh fading environment
A bit.Emulation experiment shows, in order to reduce the decoding error probability of validated user under Rayleigh fading environment, it is necessary to reduce the reality of code word
Border efficiency of transmission l/ (n+k).Work as n=380, k=20, (now actual code word efficiency is 0.125, far below n=during l=50
The code check 0.33 of code word when 280, k=20, l=100), decoding error probability and height of the validated user under Rayleigh fading environment
Validated user decoding error probability under this environment maintains an equal level, i.e., be all 4 × 10-9.Fig. 6, which gives, works as n=380, k=20, l=50
When, the relation between the decoding error probability of listener-in and the signal to noise ratio of tapping channel.It can be seen by simulation result and Fig. 6
Go out, using in the case of sacrificing the efficiency of transmission of code word as cost, the decoding error probability energy of listener-in under Rayleigh fading environment
Showing must be outstanding than under Gaussian environment, at the same under Rayleigh fading environment validated user decoding error probability energy and Gaussian environment
It is lower to maintain an equal level.
Finally, if we further reduce the efficiency of code word, for example we use n=980, k=20, l=100 rule
Then (3,2) LDPC code, now the actual efficiency of code word is 0.1.Fig. 7 gives the now decoding error probability of listener-in and eavesdropping
Relation between the signal to noise ratio of channel.Emulation experiment shows, n=980, k=20, and l=100 rule (3,2) LDPC code is auspicious
Under sharp fading environment the decoding error probability of validated user can be allowed further to reduce, reach 2 × 10-9.Meanwhile, it is not difficult by Fig. 7
Find out, now the decoding error probability of listener-in is still more outstanding than what is showed under Gaussian environment under Rayleigh fading environment.
Drawn to draw a conclusion by above emulation experiment：Firstth, under Rayleigh fading environment, regular LDPC code causes listener-in
Decoding error probability than more approaching 0.5 under Gaussian environment, it is more safe that this also allows for system；Secondth, in Rayleigh fading
Under environment, regular LDPC code causes the decoding error probability of validated user to increase, and this also allows for the decoding difficulties of validated user
Increase；3rd, the decoding difficulties in order to reduce validated user under Rayleigh fading environment, it is necessary to sacrifice the efficiency of code word, that is, pass through
Reduce l/ (n+k) to cause the reduction of validated user decoding difficulties.
Embodiments of the invention additionally provide a kind of storage medium.Alternatively, in the present embodiment, above-mentioned storage medium can
The program code for performing following steps to be arranged to storage to be used for：
S1, according to check matrix H*Message to be sent in main channel is encoded, wherein, pass through the main letter of Rayleigh fading
The coefficient fading matrix diag (h in roadb) and without decline when check matrix H determine H*, message to be sent includes：True messages sk
With random message dl-k；
S2, sends the message to be sent after being encoded.
Alternatively, in the present embodiment, above-mentioned storage medium can include but is not limited to：USB flash disk, read-only storage (ROM,
Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disc or
CD etc. is various can be with the medium of store program codes.
Alternatively, the specific example in the present embodiment may be referred to described in above-described embodiment and optional embodiment
Example, the present embodiment will not be repeated here.
Obviously, those skilled in the art should be understood that above-mentioned each module of the invention or each step can be with general
Computing device realize that they can be concentrated on single computing device, or be distributed in multiple computing devices and constituted
Network on, alternatively, the program code that they can be can perform with computing device be realized, it is thus possible to they are stored
Performed in the storage device by computing device, and in some cases, can be shown to be performed different from order herein
The step of going out or describe, they are either fabricated to each integrated circuit modules respectively or by multiple modules in them or
Step is fabricated to single integrated circuit module to realize.So, the present invention is not restricted to any specific hardware and software combination.
The preferred embodiments of the present invention are the foregoing is only, are not intended to limit the invention, for the skill of this area
For art personnel, the present invention can have various modifications and variations.Within the spirit and principles of the invention, that is made any repaiies
Change, equivalent substitution, improvement etc., should be included in the scope of the protection.
Claims (10)
1. a kind of coding method, it is characterised in that including：
According to check matrix H*Message to be sent in main channel is encoded, wherein, pass through the coefficient of Rayleigh fading main channel
Fading matrix diag (hb) and without decline when check matrix H determine the H*, the message to be sent includes：True messages sk
With random message dl-k；
Send the message to be sent after being encoded.
2. according to the method described in claim 1, it is characterised in that according to fading coefficients matrix diag (hb) and default verification square
Battle array H generation check matrix Hs*, including：The check matrix H is obtained by below equation*：
H*=diag (hb)H。
3. according to the method described in claim 1, it is characterised in that
The check matrix H*It is n+k bits for code word size, message-length is the low density parity check code LDPC code of l bits
Check matrix, wherein, k<l<N+k, the skIncluding k bit, the dl-kIncluding l-k bit, pass through the verification square
Battle array H*Code word size after being encoded to the message to be sent is n+k bits, n, and k, l is positive integer.
4. method according to claim 3, it is characterised in that the n, k, l meet below equation：
<mrow>
<mfrac>
<mrow>
<mi>l</mi>
<mo>-</mo>
<mi>k</mi>
</mrow>
<mi>n</mi>
</mfrac>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<msub>
<mi>log</mi>
<mn>2</mn>
</msub>
<mrow>
<mo>(</mo>
<mn>1</mn>
<mo>+</mo>
<msup>
<mrow>
<mo>|</mo>
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<mi>i</mi>
<mi>a</mi>
<mi>g</mi>
<mrow>
<mo>(</mo>
<msub>
<mi>h</mi>
<mi>e</mi>
</msub>
<mo>)</mo>
</mrow>
<msup>
<mi>diag</mi>
<mrow>
<mo>-</mo>
<mn>1</mn>
</mrow>
</msup>
<mrow>
<mo>(</mo>
<msub>
<mi>h</mi>
<mi>b</mi>
</msub>
<mo>)</mo>
</mrow>
<mo>|</mo>
</mrow>
<mn>2</mn>
</msup>
<msub>
<mi>SNR</mi>
<mn>2</mn>
</msub>
<mo>)</mo>
</mrow>
<mo>,</mo>
<mfrac>
<mi>l</mi>
<mrow>
<mi>n</mi>
<mo>+</mo>
<mi>k</mi>
</mrow>
</mfrac>
<mo><</mo>
<mfrac>
<mn>1</mn>
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</mfrac>
<msub>
<mi>log</mi>
<mn>2</mn>
</msub>
<mrow>
<mo>(</mo>
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<mo>+</mo>
<msub>
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<mn>1</mn>
</msub>
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</mrow>
<mo>,</mo>
<mi>k</mi>
<mo><</mo>
<mi>l</mi>
<mo><</mo>
<mi>n</mi>
<mo>+</mo>
<mi>k</mi>
</mrow>
,
Wherein, diag (he) be the corresponding Rayleigh fading tapping channel of the main channel coefficient fading matrix, SNR1,SNR2Point
Not Wei the main channel and the tapping channel signal to noise ratio, and SNR2Value be less than SNR1Value.
5. method according to claim 3, it is characterised in that methods described also includes：
The skWith the dl-kPass through the check matrix H*Code word r after codingn+k, wherein, rn+k=((sk,dl-k)·BT·
(A-1)T,sk,dl-k), H-matrix is turned to by AB type matrixes by Gaussian elimination method, A is unit matrix, unit matrix A line number and
Columns is n+k-l matrix, and B is that a line number is n+k-l, and columns is l matrix, H=diag-1(hb)H*, BTRepresenting matrix
B transposition, (A-1)TThe transposition of representing matrix A inverse matrix.
6. method according to claim 5, it is characterised in that methods described also includes：The code word rn+kActual transmissions
Efficiency is less than the channel capacity of main channel.
7. a kind of code device, it is characterised in that including：
Coding module, for according to check matrix H*Message to be sent in main channel is encoded, wherein, declined by Rayleigh
Fall the coefficient fading matrix diag (h of main channelb) and without decline when check matrix H determine the H*, the message package to be sent
Include：True messages skWith random message dl-k；
Sending module, for sending the message to be sent after being encoded.
8. device according to claim 7, it is characterised in that the coding module, for obtaining institute by below equation
State check matrix H*：
H*=diag (hb)H。
9. device according to claim 7, it is characterised in that the check matrix H that the coding module is obtained*For code
Word length is n+k bits, and message-length is the check matrix of the low density parity check code LDPC code of l bits, wherein, k<l<n+
K, the skIncluding k bit, the dl-kIncluding l-k bit, pass through the check matrix H*The message to be sent is entered
Row coding after code word size be n+k bits, n, k, l is positive integer.
10. device according to claim 9, it is characterised in that the n, k, l meet below equation：
<mrow>
<mfrac>
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<mi>l</mi>
<mo>-</mo>
<mi>k</mi>
</mrow>
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<msub>
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</msub>
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</mrow>
<msup>
<mi>diag</mi>
<mrow>
<mo>-</mo>
<mn>1</mn>
</mrow>
</msup>
<mrow>
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<msub>
<mi>h</mi>
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</msub>
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<mn>2</mn>
</msup>
<msub>
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<mn>2</mn>
</msub>
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</mrow>
<mo>,</mo>
<mfrac>
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<mrow>
<mi>n</mi>
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</mrow>
</mfrac>
<mo><</mo>
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<mn>1</mn>
<mn>2</mn>
</mfrac>
<msub>
<mi>log</mi>
<mn>2</mn>
</msub>
<mrow>
<mo>(</mo>
<mn>1</mn>
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<msub>
<mi>SNR</mi>
<mn>1</mn>
</msub>
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</mrow>
<mo>,</mo>
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<mo>,</mo>
</mrow>
1
Wherein, diag (he) be the corresponding Rayleigh fading tapping channel of the main channel coefficient fading matrix, SNR1,SNR2Point
Not Wei the main channel and the tapping channel signal to noise ratio, and SNR2Value be less than SNR1Value.
Priority Applications (2)
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| CN201610221775.0A CN107294650A (en) | 2016-04-11 | 2016-04-11 | Coding method and device |
| PCT/CN2016/098729 WO2017177610A1 (en) | 2016-04-11 | 2016-09-12 | Coding method and device |
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| CN104836635A (en) * | 2014-02-11 | 2015-08-12 | 熵敏通讯公司 | LDPC code matrix |
| CN104917558A (en) * | 2015-06-19 | 2015-09-16 | 电子科技大学 | Method for establishing unconditionally secure communication model based on combination of beam forming and security coding |
| CN105306168A (en) * | 2015-09-18 | 2016-02-03 | 西安交通大学 | Method for guaranteeing secure transmission of wireless data based on fountain codes |
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| US7631246B2 (en) * | 2006-01-09 | 2009-12-08 | Broadcom Corporation | LDPC (low density parity check) code size adjustment by shortening and puncturing |
| US9037945B2 (en) * | 2013-03-26 | 2015-05-19 | Seagate Technology Llc | Generating partially sparse generator matrix for a quasi-cyclic low-density parity-check encoder |
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| CN104836635A (en) * | 2014-02-11 | 2015-08-12 | 熵敏通讯公司 | LDPC code matrix |
| CN104917558A (en) * | 2015-06-19 | 2015-09-16 | 电子科技大学 | Method for establishing unconditionally secure communication model based on combination of beam forming and security coding |
| CN105306168A (en) * | 2015-09-18 | 2016-02-03 | 西安交通大学 | Method for guaranteeing secure transmission of wireless data based on fountain codes |
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| 吴一帆: "无条件秘密无线通信***的秘密编码设计", 《中国优秀硕士学位论文全文数据库》 * |
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