CN110518920A - A kind of error correction coding/decoding method suitable for quantum key distribution system - Google Patents
A kind of error correction coding/decoding method suitable for quantum key distribution system Download PDFInfo
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Classifications
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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
- H03M13/1102—Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
- H03M13/1105—Decoding
- H03M13/1108—Hard decision decoding, e.g. bit flipping, modified or weighted bit flipping
-
- 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
- H03M13/1102—Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
- H03M13/1148—Structural properties of the code parity-check or generator matrix
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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
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
- H04L9/0852—Quantum cryptography
- H04L9/0858—Details about key distillation or coding, e.g. reconciliation, error correction, privacy amplification, polarisation coding or phase coding
Abstract
The invention discloses a kind of error correction coding/decoding method suitable for quantum key distribution system, belong to network communication technology field, including when quantum LDPC coding, known training information position is inserted into quantum LDPC sequence, obtains quantum LDPC code to be transmitted；Quantum LDPC code to be transmitted is sent to receiving end for receiving end decoding.The present invention to being inserted into known training information position in original LDPC coded sequence, and the training information position of insertion is shared with receiving end in receiving end, and the quantum LDPC coding that receiving end will be inserted into known training information is sent to receiving end for receiving end decoding.Receiving end is in decoding, training information position is extracted from the quantum LDPC coded message received, the quick estimation to channel is realized by the training information position extracted, accurate variable node prior information is obtained, the promotion of quantum LDPC decoding performance is realized in conjunction with the prior information of variable node.
Description
Technical field
The present invention relates to network communication technology fields, in particular to one kind quantum key distribution suitable for power telecom network
The error correction coding/decoding method of system.
Background technique
Quantum key distribution system is indivisible, the irreproducible characteristic of quantum state using single photon, realizes that communication is double
Secure key distribution between side solves the safety issue of encryption key distribution in symmetric encipherment algorithm.The peace of quantum key distribution
Full property is ensured by quantum physics principle, is uniquely to obtain Strict Proof up to now, can be ensured to realize from principle without item
The communication encryption technology of part safety.The specific demand of the communication of the sensitive data as involved in some scenes, quantum key distribution system
System is the splendid selection for protecting sensitive data transmission.
Such as in the power system, most of lightguide cable link used is communicated for aerial optical cable, such as optical fiber composite overhead
Linear light cable (Optical Fiber Composite Overhead Ground Wire, OPWG) or all dielectric self-supporting light
Cable (All-dielectric Self-supporting Optical Cable, ADSS) transmission range of quantum signal and is
System stability is protected from environmental larger.Wind, lightning stroke, temperature change, the influence of the environmental factors to optical cable such as is waved and can be led icing
The physical states such as the photon polarization state of optical fiber are caused to change, since quantum state is extremely fragile, these variations lead to quantum bit
The mistakes such as bit reversal, phase bit flipping can occur in the transmission for information.To further such that just key generates rate and mistake
Accidentally rate generates large change, and whether this external environment operated the eliminating coherence effect of quantum state to quantum and can effectively realize
Conclusive effect, Quantum Error Correcting Codes (Quantum Error Correcti ngCode, QECC) are to overcome eliminating coherence at present
Most efficient method.
Error correction, i.e., in the communications in order to guarantee to receive the consistency of two end datas, transmitting terminal can valid data (referred to as
Information code element) after additional one section of additional data (referred to as supervision symbol) send together, receiving end is receiving information
It can detecte out information code element after symbol and supervision symbol and supervision symbol whether there is mistake, it can also be to the data of mistake
Error correction.There is low density parity check code (LowDensityParityCheckCode, LDPC) efficient coding to calculate with decoding
Method, and in code rate lower than can infinitely approach Shannon limit under channel capacity with the increase of code length, so in classical communication
In be widely used.
But under electric power application environment using aerial optical cable carry out quantum communications when, it is easier to by various environment because
The influence of element, the bit error rate is higher, and traditional low density parity check code is it is difficult to ensure that quantum key distribution system in power telecom network
The reliability of the accuracy of quantum key and communication of power system in system.
Summary of the invention
The purpose of the present invention is to provide a kind of error correction/encoding methods suitable for quantum key distribution system and decoding side
Method, to improve the error correcting capability of Quantum Error Correcting Codes.
In order to achieve the above object, on the one hand, the present invention provides a kind of error correcting code side suitable for quantum key distribution system
Method includes the following steps:
When quantum LDPC is encoded, it is inserted into known training information position in quantum LDPC sequence, obtains quantum to be transmitted
LDPC code；
The quantum LDPC code to be transmitted is sent to receiving end for receiving end decoding.
Further, described that known training information position is inserted into quantum LDPC sequence, obtain quantum to be transmitted
LDPC code, comprising:
It is uniformly inserted into the known training information position in the quantum LDPC sequence, obtains the amount to be transmitted
Sub- LDPC code.
Further, the known training information position is 0 or 1.
Further, when the quantum LDPC is encoded, it is inserted into known training information position in quantum LDPC sequence, obtains
To before quantum LDPC code to be transmitted, further includes:
The number of the known training information position is counted using simulation analysis.
On the other hand, a kind of error-correcting decoding method suitable for quantum key distribution system is provided, in receiving end pair
Quantum LDPC code to be transmitted as described above is decoded, comprising:
The training information position is extracted from the quantum LDPC code to be transmitted received；
According to the training information position, the initial prior probability of variable node is calculated；
Initial prior probability and pre-set maximum number of iterations based on variable node, to the quantum to be transmitted
LDPC code is iterated decoding.
Further, described according to the training information position, calculate the initial prior probability of variable node, comprising:
The corresponding interchannel noise standard deviation in each training information position is estimated using the training information position；
According to the corresponding interchannel noise standard deviation in each training information position, the initial priori for calculating the variable node is general
Rate.
Further, the initial prior probability based on variable node and pre-set maximum number of iterations, to institute
It states quantum LDPC code to be transmitted and is iterated decoding, comprising:
For current iteration process, check-node message is updated based on Tanner figure；
For current iteration process, the initial prior probability based on Tanner figure and the variable node disappears to variable node
Breath is updated；
After the check-node information and the variable node information update, calculates the total message of all variable nodes and counted
It calculates, obtains code word c；
Judge whether code word c meets
If so, decoding process terminates；
If it is not, then judging whether current iteration number reaches the pre-set maximum number of iterations；
If so, decoding process terminates；
If it is not, then carrying out next iteration.
Further, the calculation formula of the corresponding interchannel noise standard deviation sigma (n) in each training information position are as follows:
In formula: N is the sequence length of the quantum LDPC code to be transmitted, and τ is the bit interval of adjacent training information position,
I indicates the digit of training information position, and x (i) is after the hard decision of training information position as a result, when i-th of training information position is correct,
X (i) value is -1, indicates that channel disturbance is smaller around the bit, and when i-th of training information bit-errors, x (i) value is 1,
Indicate that channel disturbance is larger around the bit, a indicates empirical coefficient.
Further, described according to the corresponding interchannel noise standard deviation in each training information position, calculate the variable node
Initial likelihood ratio prior information, comprising:
In formula, L (Pi) indicating the preliminary log likelihood ratio prior information of variable node, σ (n) indicates each training information position
Corresponding interchannel noise standard deviation, y indicate the message that receiving end receives.
Further, described for current iteration process, the initial priori based on Tanner figure and the variable node is general
During rate is updated variable node message, the variable node message more new-standard cement are as follows:
Wherein, L(k)(qij) indicate updated variable node message in kth time iterative process, qijIt is to be passed from check-node
It is delivered to the information of variable node, L (Pi) indicate variable node initial likelihood ratio prior information, i indicate variable node digit,
CiIndicate check-node, CiJ indicate remove j-th of check-node outside all check-nodes, L(k)(rj`i) indicate check-node
Information.
Compared with prior art, there are following technical effects by the present invention: traditional LDPC coding and its improved coding exist
Carry out decoding optimization when, usually in conjunction with initial preset variable node prior information, using check matrix carry out error detection and
Error correction, the prior information and channel of variable node have correlation.The present invention is in receiving end to original LDPC coded sequence
Training information position known to middle insertion, and the training information position of insertion is shared with receiving end, receiving end will be inserted into known training
The quantum LDPC coding of information is sent to receiving end and decodes for receiving end.Receiving end is in decoding, from the quantum LDPC received
Extract training information position in coded message, the quick estimation to channel realized by the training information position extracted, obtain compared with
For accurate variable node prior information, the promotion of quantum LDPC decoding performance is realized in conjunction with the prior information of variable node.
Detailed description of the invention
With reference to the accompanying drawing, specific embodiments of the present invention will be described in detail:
Fig. 1 is a kind of flow diagram of error correction/encoding method suitable for quantum key distribution system；
Fig. 2 is to be inserted into training information in transmitting terminal and extract the schematic diagram of training information in receiving end；
Fig. 3 is a kind of flow diagram of error-correcting decoding method suitable for quantum key distribution system；
Fig. 4 is the overall flow schematic diagram that receiving end decodes the quantum LDPC code received；
Fig. 5 is the error-correcting performance comparison schematic diagram of different length training information position；
Fig. 6 is the graph of relation of 16 training information position error-correcting performances and a value；
Fig. 7 is the graph of relation of 32 training information position error-correcting performances and a value；
Fig. 8 is to be inserted into the quantum LDCP system of training information position and translate the quantum LDCP system for being not inserted into training information position
The BER performance comparison schematic diagram of code；
Fig. 9 is to be inserted into the quantum LDCP system of training information position and translate the quantum LDCP system for being not inserted into training information position
The number of iterations contrast schematic diagram when code.
Specific embodiment
In order to further explain feature of the invention, reference should be made to the following detailed description and accompanying drawings of the present invention.Institute
Attached drawing is only for reference and purposes of discussion, is not used to limit protection scope of the present invention.
As shown in Figure 1 to Figure 2, present embodiment discloses a kind of Error Correction of Coding sides suitable for quantum key distribution system
Method, for including the following steps S11 to S12 in transmitting terminal progress quantum LDPC coding:
When S11, quantum LDPC are encoded, it is inserted into known training information position in quantum LDPC sequence, obtains to be transmitted
Quantum LDPC code；
S12, the quantum LDPC code to be transmitted is sent to receiving end for receiving end decoding.
It should be noted that the present embodiment is inserted into quantum LDPC sequence when transmitting terminal carries out quantum LDPC coding
Known training information position, and the training information position information of insertion is shared with receiving end, the effect of the training information position is to use
The channel information of its surrounding bits position is estimated, for realizing the quick estimation to channel.The training information position information includes instruction
Practice the regularity of distribution of information bit, the quantity of training information position, the initial position of training information position and value of training information position etc..
So that when receiving end is decoded training information position can be extracted from quantum LDPC code, and according to training information position
The training information position that such as receives of transmission situation correctly or incorrectly etc., determines the peripheral information of training information position by interchannel noise
Influence size, obtain the initialization priori probability information of relatively accurate variable node, in conjunction with initialization priori probability information
It is decoded with the check matrix of LDPC code, greatly improves the decoding speed and performance of quantum LDPC code, it is non-to be often used and relate to
And the scene of sensitive data transmission, such as this biggish channel affected by environment of power communication system, for quantum key point
The application of hair system in the power communication network plays certain guaranteeing role.
A further improvement of the present invention lies in that: known training information position is fixed as 0 or 1.It can be in quantum LDPC sequence
In be uniformly inserted into training information position or radom insertion training information position or be inserted into training information positions according to other rules.And it will
The insertion rule of training information position and receiving end are shared.In receiving end, trained letter is extracted from the quantum LDPC code received
Breath position simultaneously makes decisions, the training information position information for comparing the information of judgement and sharing in advance, according to comparing result to receiving
Code word carry out decoding probability initialization: if mistake occurs for the training information position that receives of receiving end, then it is assumed that the training information
Position has received stronger interchannel noise interference, and the probability that mistake occurs for the information bit of training information position two sides also increases accordingly；Together
Reason, if the training information position that receiving end receives is correct, the interchannel noise that the information bit of the training information position two sides receives
Annoyance level is smaller, training information position two sides information bit can the probability that is properly received of receiving end will improve.
It in practical applications, can not when being inserted into training information position in quantum LDPC sequence by the way of random distribution
Guarantee training information position effective influence range, for example, all training information positions it is adjacent to each other be inserted into quantum LDPC sequence
When middle, the coverage that will lead to training information position is only limited to appear on several bits around training information position,
And it cannot cover on other bits.And training information position can not be correctly extracted in receiving end.
When using other rule insertion training information positions, receiving end needs to know the insertion rule of training information position, and
It not can guarantee and accurately and rapidly extract training information position.
Added i.e. in quantum LDPC sequence every equal number of bit by the way of uniformly insertion training information position
Add a training information position.It can guarantee training information position effective influence range, and need to only know first in receiving end
The bit interval of the initial position of training information position and adjacent trained position, can be accurate from the quantum LDCP code received, fast
Speed extracts training information position.
Therefore, the present embodiment uses even distribution pattern, will be in the equally spaced insertion quantum LDPC sequence in training information position.
And by the initial position of first training information position, the bit interval of adjacent trained position and value of first training information position etc.
Information and receiving end are shared.
In practical applications, since the effect of training information position is the channel information for estimating its surrounding bits, without accurate
The correctness that bit each around it is received judge that there is no need to be inserted into quantity in quantum LDPC sequence
Excessive training information position, if the training information position that insertion is excessive, will increase the redundancy of quantum LDPC code, to reduce quantum
The code efficiency of LDPC code.Therefore it is as the further improvement of the present invention: known to the insertion into quantum LDPC sequence
Training information position before, the optimum number of training information position is also gone out by analysis of simulation experiment.
As shown in figure 5, the present embodiment passes through emulation experiment, different length are inserted into the quantum LDPC sequence that code length is 1024
Behind the training information position of degree, in the comparison of the decoding performance of receiving end, figure, OSNR is optical signal to noise ratio (Optical Signal
Noise Ratio), BER be the bit error rate (Bit Error Rate), it can be seen that with insertion training information bit quantity it is continuous
Increase, the error code curve of receiving end decoding tends to be horizontal after reducing before this, the minimum training information position when guaranteeing that BER value is minimum
Quantity 30 or so.
It should be noted that in the present embodiment with code length be 1024 quantum LDPC sequence when the training information digit be inserted into
Amount is illustrated for being 30, in practical application, those skilled in the art can be according to the code length of specific quantum LDPC sequence
Emulation experiment is carried out, the quantity of the training information position of addition is analyzed.
As shown in figure 3, being used for present embodiment discloses a kind of error-correcting decoding method suitable for quantum key distribution system
The quantum LDPC code to be transmitted that above-mentioned transmitting terminal is sent is decoded in receiving end, includes the following steps S21 to S23:
S21, the training information position is extracted from the quantum LDPC code to be transmitted received；
S22, hard decision is carried out to the training information position, the initial priori for calculating variable node according to court verdict is general
Rate；
S23, the initial prior probability based on variable node and pre-set maximum number of iterations, to described to be transmitted
Quantum LDPC code is iterated decoding.
It should be noted that receiving end extracts and adjudicates to the training information position in the quantum LDPC code received,
Judgement is " 1 " when greater than 0, and judgement is " 0 " when less than 0, the training information position that the information and transmitting terminal for then comparing judgement are sent
Information, according to comparing result to receiving end received by code word carry out decoding probability initialization, to training information position two sides
Information bit be correctly received and be erroneously received the probability at end and estimated, to realize the speed of quantum LDPC code decoding
And performance.
The present invention the further improvement lies in: above-mentioned steps S22: according to the training information position, calculate variable node
Initial prior probability specifically includes following subdivided step S221 to S222:
S221, the corresponding interchannel noise standard deviation in each training information position is estimated using training information position.
Specifically, the calculation formula of interchannel noise standard deviation sigma (n) corresponding to each training information position are as follows:
In formula: N is the sequence length of the original quantum LDPC code to be transmitted, and τ is the bit of adjacent training information position
Interval, i indicate the digit of training information position, x (i) be it is after the hard decision of training information position as a result, when i-th of training information position just
When true, x (i) value is -1, indicates that channel disturbance is smaller around the bit, when i-th of training information bit-errors, x (i) value
It is 1, indicates that channel disturbance is larger around the bit,SNR indicates that signal-to-noise ratio, R indicate code rate, and a expression is repaired
Positive parameter.
S222, according to the corresponding interchannel noise standard deviation in each training information position, calculate the initial elder generation of the variable node
Test probability.
Specifically, the initial prior probability L (P of variable nodei) calculation formula it is as follows:
Then have
In formula: L(0)(qi'j) it is the initial information that check-node is transmitted to from variable node, σ (n) indicates each training letter
Cease the corresponding interchannel noise standard deviation in position, xiIndicate original code word, y indicates the message that receiving end receives.
It should be noted that σ (n) reduces, initial prior probability L (P when training information position is correcti) increase, training letter
When ceasing bit-errors, σ (n) increases, initial prior probability L (Pi) reduce.
Specifically, i.e., the process for being iterated decoding to quantum LDPC code includes check-node information updating, variable node
Information updating and decoding judgement, as shown in figure 4, above-mentioned steps S23: initial prior probability based on variable node and setting in advance
The maximum number of iterations set is iterated decoding to the quantum LDPC code to be transmitted, specifically includes following subdivided step
S231 to S23:
S231, check-node information updating: for current iteration process, check-node message is carried out based on Tanner figure
It updates；
Specifically, to kth time iteration (1≤k≤Imax, ImaxIndicate pre-set maximum number of iterations), check-node
cjExternal information along the side of Tanner figure from variable node v adjacent theretoi(i ∈ R (j)) is passed over, and calculates verification section
The expression formula of point information updating are as follows:
In formula: L(k)(rji) indicate updated check-node message in kth time iterative process, rijIt is to be passed from check-node
It is delivered to the information of variable node, j indicates the digit of check-node, RjIndicate variable node, RjI indicate remove i-th of variable section
Variable node outside point, L(k)(qi'j) indicate variable node information.
S232, variable node message update: for current iteration process, being schemed based on Tanner first with the variable node
Beginning prior probability is updated variable node message；
Specifically, to kth time iteration, variable node viExternal information from check-node c adjacent theretoj(j∈C(i))
It passes over, calculates the expression formula that variable node message updates are as follows:
In formula: L(k)(qij) indicate updated variable node message in kth time iterative process, qijIt is to be passed from variable node
It is delivered to the information of check-node, L (Pi) indicate variable node initial likelihood ratio prior information, i indicate variable node digit,
CiIndicate check-node, CiJ indicate remove j-th of check-node outside all check-nodes, L(k)(rj`i) indicate check-node
Information.
S233, decoding judgement: after check-node information and variable node information update, all variable nodes is calculated and are always disappeared
Breath is calculated, and code word c is obtained；
Specifically, after check-node each time and variable node update, all variable node total informations are carried out
It calculates, all variable node total informations are the superpositions that check-node transmits message and channel transfer message
IfThenOtherwise
S234, judge whether code word c meetsWherein H is check matrix, if so, thening follow the steps
S235, if it is not, thening follow the steps S236；
S235, decoding process terminate；
S236, judge whether current iteration number reaches the pre-set maximum number of iterations, if so, executing step
Rapid S235, if it is not, thening follow the steps S231 to carry out next iteration.
The present invention the further improvement lies in: the value of parameter a be inserted into the number of training information position it is related, can pass through
The optimal value of emulation experiment acquisition parameter a.The present embodiment, as emulation tool, analyzes interchannel noise standard using Matlab
The optimum results of a in the calculation formula of poor σ (n), and by it compared with traditional LDPC algorithm carries out emulation under identical environment, it imitates
It is 1024 that LDPC code word length is chosen in very, as a result as shown in Figure 6 to 7.
It can be seen from the figure that the size of corrected parameter a value can determine training information position to the estimation model of channel disturbance
It encloses.If a value is bigger, then training information position also will be smaller to the coverage of surrounding bits；If a value is smaller, due to
The coverage of adjacent training information position can overlap, bit upper estimate is caused to generate aliasing, i.e. a training information
Its estimated value in a certain range has been passed to the bit except its estimation range by position, to affect the correct of this bit
Estimation.If generating the aliasing of estimated value, the initialization information for decoding process cannot be improved, thus the decoding affected
Performance, therefore the selection of a value will have a direct impact on the error correcting capability of decoding.
And for a LDPC code word, it can't become more because of the training information position of addition, error-correcting performance just improves.
Because if the training information position being added is excessive, the bit interval of adjacent training information position just becomes smaller, even if then the value of a is very
Small, the coverage that will also result in two neighboring training information position overlaps.
It is equal to 1024 code word for code length, the value of corrected parameter a is set forth to decoding BER performance in Fig. 6 and Fig. 7
Influence, from fig. 6, it can be seen that for the decoding algorithm containing 16 training information positions, 0.01 is the optimal selection of a；And it is right
In the optimal value of the decoding algorithm containing 32 training information positions, a be then 0.04.
It should be understood that the specific value of two kinds of the corrected parameter a that the present embodiment provides is by way of example only, this field
Technical staff can carry out related emulation experiment, analyze the optimal of corrected parameter a according to the number for being actually inserted into training information position
Value, specific simulation analysis process are as follows: according to the digit of selected information bit, change system parameter values (such as OSNR), calculate not
With the code performance that entangles under a, and then analyzes and obtain optimal value.
The comparison between the LDPC code that training information position is added and traditional LDPC code is described in Fig. 8.If it is desired to which BER is lower than
10-9, OSNR reduction 0.35dB of the LDPC code than traditional LDPC code of 16 training information positions is added；And 32 training letters are added
The LDPC code for ceasing position reduces 0.45dB than the OSNR of traditional LDPC code.
Fig. 9 describes pair between the LDPC code of the position containing training information and the average decoding iteration number of traditional LDPC code
Than.From fig. 9, it can be seen that decoding of the LDPC code than traditional LDPC code of the position containing training information restrains in biggish signal-to-noise ratio
Speed has wanted fast nearly 1 times, thus the efficiency with higher decoding algorithm.
Simulation result shows that the LDPC decoding method in the present invention can be further improved error-correcting performance and convergence speed
Degree, so that quantum key distribution system resists the ability enhancing of electric power optical cable adverse circumstances, to ensure quantum key distribution system
System still can preferably be run under the influence of electric power environmental, ensure that the accuracy of quantum key in communication of power system, be improved
The reliability of communication of power system.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (10)
1. a kind of error correction/encoding method suitable for quantum key distribution system characterized by comprising
When quantum LDPC is encoded, it is inserted into known training information position in quantum LDPC sequence, obtains quantum LDPC to be transmitted
Code；
The quantum LDPC code to be transmitted is sent to receiving end for receiving end decoding.
2. as described in claim 1 be suitable for quantum key distribution system error correction/encoding method, which is characterized in that it is described
It is inserted into known training information position in quantum LDPC sequence, obtains quantum LDPC code to be transmitted, comprising:
It is uniformly inserted into the known training information position in the quantum LDPC sequence, obtains the quantum to be transmitted
LDPC code.
3. being suitable for the error correction/encoding method of quantum key distribution system as claimed in claim 1 or 2, which is characterized in that institute
Stating known training information position is 0 or 1.
4. being suitable for the error correction/encoding method of quantum key distribution system as claimed in claim 2, which is characterized in that described
When quantum LDPC is encoded, known training information position is inserted into quantum LDPC sequence, obtain quantum LDPC code to be transmitted it
Before, further includes:
The number of the known training information position is counted using simulation analysis.
5. a kind of error-correcting decoding method suitable for quantum key distribution system, which is characterized in that be used in receiving end to such as power
Benefit requires any one of 1-4 quantum LDPC code to be transmitted to be decoded, comprising:
The training information position is extracted from the quantum LDPC code to be transmitted received；
According to the training information position, the initial prior probability of variable node is calculated；
Initial prior probability and pre-set maximum number of iterations based on variable node, to the quantum LDPC to be transmitted
Code is iterated decoding.
6. being suitable for the error-correcting decoding method of quantum key distribution system as claimed in claim 5, which is characterized in that described
According to the training information position, the initial prior probability of variable node is calculated, comprising:
The corresponding interchannel noise standard deviation in each training information position is estimated using the training information position；
According to the corresponding interchannel noise standard deviation in each training information position, the initial prior probability of the variable node is calculated.
7. being suitable for the error-correcting decoding method of quantum key distribution system as claimed in claim 5, which is characterized in that the base
Initial prior probability and pre-set maximum number of iterations in variable node carry out the quantum LDPC code to be transmitted
Iterative decoding, comprising:
For current iteration process, check-node message is updated based on Tanner figure；
For current iteration process, the initial prior probability based on Tanner figure and the variable node to variable node message into
Row updates；
After the check-node information and the variable node information update, calculates the total message of all variable nodes and is calculated,
Obtain code word c；
Judge whether code word c meets
If so, decoding process terminates；
If it is not, then judging whether current iteration number reaches the pre-set maximum number of iterations；
If so, decoding process terminates；
If it is not, then carrying out next iteration.
8. being suitable for the error-correcting decoding method of quantum key distribution system as claimed in claim 6, which is characterized in that described every
The calculation formula of the corresponding interchannel noise standard deviation sigma (n) in a training information position are as follows:
In formula: N is the sequence length of the quantum LDPC code to be transmitted, and τ is the bit interval of adjacent training information position, i table
Show the digit of training information position, x (i) is after the hard decision of training information position as a result, when i-th of training information position is correct, x
(i) value is -1, indicates that channel disturbance is smaller around the bit, and when i-th of training information bit-errors, x (i) value is 1, table
Show that channel disturbance is larger around the bit, a indicates empirical coefficient.
9. being suitable for the error-correcting decoding method of quantum key distribution system as claimed in claim 6, which is characterized in that described
According to the corresponding interchannel noise standard deviation in each training information position, the initial likelihood ratio prior information of the variable node is calculated, is wrapped
It includes:
In formula, L (Pi) indicating the preliminary log likelihood ratio prior information of variable node, σ (n) indicates that each training information position is corresponding
Interchannel noise standard deviation, y indicates the message that receives of receiving end.
10. being suitable for the error-correcting decoding method of quantum key distribution system as claimed in claim 7, which is characterized in that described
For current iteration process, the initial prior probability based on Tanner figure and the variable node carries out more variable node message
In new, the variable node message more new-standard cement are as follows:
Wherein, L(k)(qij) indicate updated variable node message in kth time iterative process, qijIt is to be transmitted to from check-node
The information of variable node, L (Pi) indicate variable node initial likelihood ratio prior information, i indicate variable node digit, CiTable
Show check-node, CiJ indicate remove j-th of check-node outside all check-nodes, L(k)(rj`i) indicate check-node letter
Breath.
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