CN105846958B - Distributed system Raptor decoding transmission method towards deep space communication - Google Patents
Distributed system Raptor decoding transmission method towards deep space communication Download PDFInfo
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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
- H04L1/0076—Distributed coding, e.g. network coding, involving channel coding
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- H—ELECTRICITY
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- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
Abstract
The present invention provides a kind of distributed system Raptor decoding transmission method towards deep space communication, comprising the following steps: step S1 is to code length respectivelyK 1WithK 2Information source end raw information carry out system Raptor coding and being sent to the same relaying；Step S2, relayingRCoded identification from information source end is respectively stored in buffer areaE 1And buffer areaE 2In, the rear of data processing is then carried out using DSRC algorithm and is sent to destination；Step S3, destinationDThe coded identification received is decoded.The present invention is devised for multiple detectors by the distributed system Raptor decoding transmission method under orbiter, orbital vehicle to the ground transmitting scene, propose the reduction procedure of joint decoding, theory analysis has derived the performance parameter of DSRC scheme and its improvement project, and entangled without rate compared with the scheme of deleting carries out emulation with the distribution of the prior art, 99% decoding success rate is obtained when redundancy reaches 5%.
Description
Technical field
The present invention relates to a kind of coding and transmission method towards deep space communication more particularly to a kind of points towards deep space communication
Cloth system Raptor decoding transmission method.
Background technique
With the diversification of deep space exploration task and the continuous extension of investigative range, the data volume and service class for needing to transmit
Type increasingly increases, the demand of the multimedia data services such as image, video, voice of the deep space exploration that especially faces the future, existing
Point-to-point safeguard of some based on physics flow gain is hard to carry on, is using relaying, cooperation or even Network Transmitting
The inexorable trend of the following deep space communication development；" the space interconnection strategies group " set up by each space flight tissue in the world including China
(SISG), it establishes to hold late/appearance circuit network (Delay/Disruption Tolerant Networks, DTN) protocol architecture
For core, consultative committee for space data system's (CCSDS) relevant criterion and suggestion are surrounded, TT&C Resources at different levels are integrated, established
Deep space exploration communication network.
The mars exploration task run at present and correlative study have turned to the mode of relay satellite networking from Dan Xing, single user.
" curious number " the mars exploration vehicle to land in October, 2012 passes through " Odyssey " and " Mars reconnaisance orbit device " and returns to the earth
Most video and image data, relayed communications rate reach 40 times of the link that direct transfers or more；However, even if using multi-hop
The one hop link distance of networking transmission, the communication of deep space interplanetary is still greater than near-earth satellite communication distance with multiple orders of magnitude, existing
Approached shannon limit channel coding and can not correct all bit-errors.And between Mars-earth when propagation in 3-20 minutes
Prolong, so that the confirmation retransmission scheme efficiency of existing transport protocol is very low.
Based on this, CCSDS proposes to utilize the data point that long correcting and eleting codes (Long Erasure Code, LEC) is transport layer
Group provides forward erasure correction ability, and by the way that the packet switched channels for having error-detection mechanism are equivalent to erasure channel, LEC is to data
Grouping carries out erasure code, enables destination D using the information block deleting packet recovery and being deleted is entangled, to reduce feedback weight
Number is passed, efficiency of transmission is promoted.The research of LEC at present is in the starting stage, and digital fountain is as a kind of encoding and decoding complexity
It is lower, can have proved to be one kind with any probabilistic approximation shannon limit without code rate forward erasure correction group technology and be suitable for
The LEC erasure code scheme of deep space communication.In addition, relaying orbiter, orbital vehicle use asynchronous store-and-forward mechanism, can without the concern for
It under the premise of the synchronization of link layer, is encoded using the asynchronous LEC of design data received in caching, is multiple tested star catalogue faces
Node provides distributed relay transmission.
Summary of the invention
The technical problem to be solved by the present invention is to need to provide one kind to can be improved decoding success rate under deep space communication
Distributed system Raptor decoding transmission method.
In this regard, the present invention provides a kind of distributed system Raptor decoding transmission method towards deep space communication, including following
Step:
Step S1 is respectively K to code length1And K2Information source end raw information carry out system Raptor coding and be sent to same
One relaying；
Step S2 relays R for the coded identification from information source end and is respectively stored in buffer area E1With buffer area E2In, then
The rear of data processing is carried out using DSRC algorithm to send to destination；
Step S3, destination D decode the coded identification received.
A further improvement of the present invention is that the system Raptor cataloged procedure of information source end is by K in the step S1
After a source symbol C zero padding, by the intermediate generator matrix G of Preudo-Random Sequences Generation, L intermediate symbols C ' is generated, and meet
Following formula:Wherein, intermediate generator matrix G includes S LDPC coding symbol
Number GLDPC, H Half coded identification GHalfWith K LT coded identification GLT, L=S+H+K, ISFor S row, S arrange unit matrix, 0S×H
For the null matrix that S row, H are arranged, IHThe unit matrix arranged for H row, H；S, L, H and K are natural number, represent encoder matrix row and
Column；Intermediate symbols C ' carry out LT is encoded again and generates redundancy encoding packet, encoder matrix is labeled as RLT；Then it successively sends original
Symbol and redundancy encoding symbol.Wherein, formulaIt is each in middle square brackets
What pa-rameter symbols represented is the submatrix arrangement schematic construction an of internal matrix.
A further improvement of the present invention is that in the step S1, the information source W of information source end1With information source W2Independently into
Then row system Raptor coding sends its original symbol and redundancy encoding symbol to relaying R, and be respectively stored in buffer area E1
With buffer area E2In；Wherein, in step s 2, the relaying R passes through buffer area E1,wWith buffer area E2,wInformation source W is cached respectively1With
Information source W2Original symbol, pass through buffer area E1,rWith buffer area E2,rInformation source W is cached respectively1With information source W2Redundancy encoding symbol
Number.
A further improvement of the present invention is that in the step S2, information source W1With information source W2Corresponding coded identification difference
It is P through probability of erasurewr1And Pwr2Erasure channel reach relaying R.
A further improvement of the present invention is that relaying R carries out data processing packet using DSRC algorithm in the step S2
Include following sub-step:
Step S201, forwarding cache area E1,wOr buffer area E2,wIn original symbol, until the original symbol of caching is whole
Forwarding finishes；
Step S202 realizes distributed coding forwarding by relaying R.
A further improvement of the present invention is that in the step S201, if buffer area E1,wOr buffer area E2,wCaching it is non-
Sky, then at random from buffer area E1,wOr buffer area E2,wOne original symbol of middle selection is forwarded, original until all cachings
Symbol forwarding finishes, then go to step S202.
A further improvement of the present invention is that the step S202 in a manner of following three kinds in any one realize distribution
Formula coding forwarding: at random from buffer area E1,rOr buffer area E2,rIt is middle to choose the i.e. storage forwarding of redundancy encoding symbol realization；From
Buffer area E1,rWith buffer area E2,rIn respectively randomly select redundancy encoding symbol and realize exclusive or forwarding；And at random from caching
Area E1,wOr buffer area E2,wOne original symbol of middle selection, from buffer area E2,rOr buffer area E1,rIn randomly select one it is superfluous
Remaining coded identification, and then realize exclusive or forwarding.
A further improvement of the present invention is that it is P that coded identification, which is passed through probability of erasure, in the step S3rdR-D
Section link reaches destination D, carries out simplified processing by confederate matrix shift process first, then to it is remaining can not unit
The stopping collection matrix of change carries out Gauss decoding.
A further improvement of the present invention is that the step S3 includes following sub-step:
Step S301, init state, and elementary row operations are made to decoding matrix and arrange elementary exchange；
Step S302, by row transformation and transformation disappear member realize matrix reduction；
Step S303 realizes that decoding matrix is unitization, and decoding terminates.
A further improvement of the present invention is that in the step S301, init state, respectively to piecemeal A1With piecemeal A2
Make elementary row operations and arrange elementary exchange simplification matrix for the first time, then utilizes obtained I1And I2To RLTMake the member processing that disappears,
In, piecemeal A1For information source W1Corresponding intermediate generator matrix G1, piecemeal A2For information source W2Corresponding intermediate generator matrix G2, I1For
Piecemeal A1The resulting unit matrix of abbreviation after progress elementary transformation, I2For piecemeal A2The resulting unit of abbreviation after progress elementary transformation
Battle array, RLTFor the generator matrix for carrying out the redundant symbol that random exclusive or obtains to the redundant symbol from two information sources；The step
In S302, by U1And U2It is divide into upper part and lower part, by elementary row operations by U1,lowAnd U2,lowBecome upper triangular matrix, and utilizes
Transformed U1,lowAnd U2,lowTo piecemeal [0, B1、0、B2] make to go to convert the member that disappears, then suitable row is therefrom selected to add to
U1,lowAnd U2,low, obtain C1And C2, wherein U1For to piecemeal A1It is the L row of generation, unknown after the elementary transformation for carrying out the first stage
The non-zero matrix of columns；Piecemeal U2For to piecemeal A2After the elementary transformation for carrying out the first stage, the L row of generation, unknown columns
Non-zero matrix, U1,lowFor to U1Upper triangular matrix after carrying out elementary transformation, U2,lowFor to U2Upper three after carrying out elementary transformation
Angular moment battle array, piecemeal [0, B1、0、B2] it is that the non-zero matrix after elementary transformation, piecemeal C are carried out to RLT1For to U1Carry out elementary change
It changes and obtains upper triangular matrix U1,lowRemaining submatrix afterwards, piecemeal C2For to U2It carries out elementary transformation and obtains upper triangular matrix
U2,lowRemaining submatrix afterwards；In the step S303, cast out remaining M-2L row, piecemeal is labeled as A11And A22, and it is single respectively
Positionization, decoding terminate, wherein M is the line number of the joint decoding matrix received, and L is determined by input information source code length K
The code length of systematic code, A11And A22It is the simplified matrix of joint decoding.
Compared with prior art, the beneficial effects of the present invention are: be based on delay-disruption tolerant network (DTN) protocol frame, benefit
Multi-hop relay networking transmission is carried out with orbiter, orbital vehicle, is devised for multiple detectors by under orbiter, orbital vehicle to the ground transmitting scene
Distributed system Raptor decoding transmission method, propose the reduction procedure of joint decoding, theory analysis has derived DSRC scheme
And its performance parameter of improvement project, and entangled without rate compared with the scheme of deleting carries out emulation with the distribution of the prior art, in redundancy
99% decoding success rate is obtained when reaching 5%.
Detailed description of the invention
Fig. 1 is the Y moldeed depth sky communication network schematic diagram of an embodiment of the present invention；
Fig. 2 is the decoding matrix schematic diagram of an embodiment of the present invention；
Fig. 3 is the joint decoding matrixing flow diagram of the step S3 of an embodiment of the present invention；
Fig. 4 is performance evaluation schematic diagram of an embodiment of the present invention based on and/or tree；
Fig. 5 is the progressive performance analogous diagram of decoding of the DSRC repetition policy of an embodiment of the present invention；
Fig. 6 is to change the decoding of information source to the packet loss between relaying R in the DSRC scheme of an embodiment of the present invention
It can analogous diagram；
Fig. 7 is to change to relay translating for the packet loss between R to destination D in the DSRC scheme of an embodiment of the present invention
Code performance analogous diagram；
Fig. 8 be an embodiment of the present invention DSRC scheme compared with the performance between the prior art analogous diagram；
Fig. 9 is the decoding performance analogous diagram of DSRC scheme of an embodiment of the present invention under different parameters.
Specific embodiment
With reference to the accompanying drawing, preferably embodiment of the invention is described in further detail:
This example provides a kind of distributed system Raptor decoding transmission method towards deep space communication, comprising the following steps:
Step S1 is respectively K to code length1And K2Information source end raw information carry out system Raptor coding and be sent to same
One relaying；
Step S2 relays R for the coded identification from information source end and is respectively stored in buffer area E1In buffer area E2, so
The rear of data processing is carried out using DSRC algorithm afterwards to send to destination；
Step S3, destination D decode the coded identification received.
This example utilizes the communication of orbiter, orbital vehicle relaying passback science data for following tested celestial body surface detector joint
Scene, as shown in Figure 1, there are two the Y type topologys of information source, Dan Zhongji R and single destination D for one tool of design, wherein information source end
Information source be also referred to as information source node, relaying R is also referred to as relay node, and destination D is also referred to as destination node；It is different then in conjunction with DTN
Store-and-forward mechanism is walked, this example devises distributed system Raptor decoding transmission method for deep space communication network, i.e.,
Distributed Systematic Raptor Coding scheme, abbreviation DSRC scheme；Further, this example considers deep space
Detector energy and relaying orbiter, orbital vehicle storage capacity are limited, propose default message sink coding symbol quantity and junction network is compiled
The prioritization scheme of code, can effectively reduce encoding overhead；Finally, by simulating, verifying and analyzing DSRC scheme described in this example
Performance.
Since the orbiter, orbital vehicle as relay node has the characteristics that periodic interruptions, designed in existing terrestrial wireless communication
Distributed correcting and eleting codes scheme and not applicable DSN deep space network network；Further to promote the effective throughput under practical scene, this
Example is intended deleting processing expense using system Raptor code in information source end to reduce probe vehicles and entangling for relaying；The Raptor code LT
The modified version that developed on the basis of code, and LT code is general digital fountain code.
In Fig. 1, the course of work of each node in transmission process is as described below: information source end, information source W1With information source W2Phase
It is mutually independent, it is respectively K to code length1And K2Raw information system Raptor coding and send；R is relayed, code length is respectively
K1And K2Information source W1With information source W2Raw information coded identification respectively through probability of erasure be Pwr1And Pwr2Erasure channel arrive
Up to relaying R, relaying R will come from information source W1With information source W2Coded identification be respectively stored in buffer area E1With buffer area E2In, so
Being executed afterwards using DSRC algorithm includes the operation such as exclusive or, discarding and forwarding, is sent to destination；Destination D, coded identification warp
Crossing probability of erasure is PrdR-D section link reach destination D, simplified processing is carried out by confederate matrix shift process first, so
Gauss decoding is carried out to remaining stopping collection matrix that can not be unitization afterwards.
In the step S1, the system Raptor cataloged procedure of information source end be by K source symbol C zero padding after, pass through puppet
The intermediate generator matrix G of random sequence construction, generates L intermediate symbols C ', and meet following formula:Wherein, intermediate generator matrix G includes S LDPC coded identification GLDPC、H
A Half coded identification GHalfWith K LT coded identification GLT, L=S+H+K, ISFor S row, S arrange unit matrix, 0S×HFor S row, H
The null matrix of column, IHThe unit matrix arranged for H row, H；S, L, H and K are natural number, represent the row and column of encoder matrix；It is right again
Intermediate symbols C ' carry out LT coding generates redundancy encoding packet, and encoder matrix is labeled as RLT；Then original symbol and superfluous is successively sent
Remaining coded identification.The original symbol is also referred to as system symbol.Wherein, formula
Parameters symbology in middle square brackets be an internal matrix submatrix arrangement schematic construction, belong in matrix
Submatrix expression formula literary style.
In the present embodiment, different K corresponds to different L, such as K=16, and 17,18 corresponding L are 24；K=244,255,
When 266, L 264, this be can be adjusted according to the actual situation；As shown in Fig. 2, in the matrix of the first row, total S row, L
Column；GLDPCIt is arranged including S row, (L-H-S)；ISThe unit matrix arranged for S row, S；0S×HThe null matrix arranged for S row, H.In second row, altogether
H row, L column；GHalfIt is arranged including H row, (L-H)；IHThe unit matrix arranged for H row, H；In the third line, total K row, L column；GLTIncluding K
Row, L column；The configuration of matrix G, such as the submatrix A of decoding matrix A1Or A2, as shown in Figure 2.
In step S1 described in this example, the information source W of information source end1With information source W2Independently carry out system Raptor coding then
Its original symbol and redundancy encoding symbol are sent to relaying R, and is respectively stored in buffer area E1With buffer area E2In；Wherein, in step
In rapid S2, the relaying R passes through buffer area E1,wWith buffer area E2,wInformation source W is cached respectively1With information source W2Original symbol, pass through
Buffer area E1,rWith buffer area E2,rInformation source W is cached respectively1With information source W2Redundancy encoding symbol.
In step S2 described in this example, information source W1With information source W2Corresponding coded identification is respectively P through probability of erasurewr1And Pwr2
Erasure channel reach relaying R.
In step S2 described in this example, it includes following sub-step that relaying R, which carries out data processing using DSRC algorithm:
Step S201, forwarding cache area E1,wOr buffer area E2,wIn original symbol, until the original symbol of caching is whole
Forwarding finishes；
Step S202 realizes distributed coding forwarding by relaying R.
Wherein, in the step S201, if buffer area E1,wOr buffer area E2,wCaching non-empty, then at random from buffer area
E1,wOr buffer area E2,wOne original symbol of middle selection is forwarded, and is finished, is then jumped until the original symbol of all cachings forwards
Go to step S202.
The step S202 in a manner of following three kinds in any one realize distributed coding forwarding: first way,
At random from buffer area E1,rOr buffer area E2,rIt is middle to choose the i.e. storage forwarding of redundancy encoding symbol realization, in Figure of description 5
In Fig. 9, which is expressed as mode 1；The second way is from buffer area E1,rWith buffer area E2,rIn respectively randomly select
One redundancy encoding symbol realizes exclusive or forwarding, and in Figure of description 5 and Fig. 9, which is expressed as mode 2；With
And the third mode, at random from buffer area E1,wOr buffer area E2,wOne original symbol of middle selection, from buffer area E2,rOr caching
Area E1,rIn a redundancy encoding symbol randomly selecting, and then realize exclusive or forwarding, in Figure of description 5 and Fig. 9, this
Three kinds of modes are expressed as mode 3.
It is noted that DSRC scheme approximately equivalent is extended in the decoding matrix for arranging two L is greater than 2L for one
The joint decoding matrix of column.
Destination D reconstructs decoding matrix A after receiving M (M > 2L) a coded identification first, as shown in Fig. 2, joint decoding
Decoding matrix is extended, then it is original 8 times that the algorithm complexity of Gauss decoding, which increases,；Therefore, this example further preferably proposes step
The simplified decoding algorithm of 0 matrix of optimization processing piecemeal of S3.
In step S3 described in this example, it is P that coded identification, which is passed through probability of erasure,rdR-D section link reach destination D, adopt
It is based on the Gauss decoding algorithm for stopping collection.Specifically, the step S3 includes following sub-step:
Step S301, init state, and elementary row operations are made to decoding matrix and arrange elementary exchange；
Step S302, by row transformation and transformation disappear member realize matrix reduction；
Step S303 realizes that decoding matrix is unitization, and decoding terminates.
In the step S301, init state, as shown in Fig. 3 (a), respectively to piecemeal A1With piecemeal A2Make the elementary change of row
Elementary exchange simplification matrix for the first time is changed and arranged, Fig. 3 (b) is obtained, then utilizes obtained I1And I2To RLTMake the member processing that disappears, obtains
Fig. 3 (c), wherein piecemeal A1For information source W1Corresponding intermediate generator matrix G1, piecemeal A2For information source W2Corresponding intermediate generation square
Battle array G2, I1For piecemeal A1The resulting unit matrix of abbreviation after progress elementary transformation, I2For piecemeal A2After progress elementary transformation obtained by abbreviation
Unit matrix, RLTFor the generator matrix for carrying out the redundant symbol that random exclusive or obtains to the redundant symbol from two information sources；Institute
It states in step S302, by U1And U2It is divide into upper part and lower part, by elementary row operations by U1,lowAnd U2,lowBecome upper triangular matrix,
And utilize transformed U1,lowAnd U2,lowTo piecemeal [0, B1、0、B2] make to go to convert the member that disappears, then therefrom select suitable row to mend
It is charged to U1,lowAnd U2,low, obtain C1And C2, wherein U1For to piecemeal A1After the elementary transformation for carrying out the first stage, the L row of generation,
The non-zero matrix of unknown columns；Piecemeal U2For to piecemeal A2After the elementary transformation for carrying out the first stage, L row, the non-pivot column of generation
Several non-zero matrix, U1,lowFor to U1Upper triangular matrix after carrying out elementary transformation, U2,lowFor to U2After carrying out elementary transformation
Upper triangular matrix, piecemeal [0, B1、0、B2] it is that the non-zero matrix after elementary transformation, piecemeal C are carried out to RLT1For to U1It carries out just
Equal transformation obtain upper triangular matrix U1,lowRemaining submatrix afterwards, piecemeal C2For to U2It carries out elementary transformation and obtains upper three angular moment
Battle array U2,lowRemaining submatrix afterwards；In the step S303, cast out remaining M-2L row, piecemeal is labeled as A11And A22, and point
Not unitization, decoding terminates, wherein M is the line number of the joint decoding matrix received, and the M is by information source W1With information source W2It produces
Raw coded identification, corresponding generator matrix G1And G2After zero padding, generated in the first stage of relaying algorithm, so be 2L,
In addition the exclusive or redundant symbol that second stage generates, i.e. RLT, line number > 0；So M > 2L；L is is determined by input information source code length K
Systematic code code length； A11And A22It is the simplified matrix of joint decoding, with the matrix indistinction in Fig. 3 (c).If decoding
Matrix cannot be unitization, then decoding failure.
This example is based on delay-disruption tolerant network (DTN) protocol frame, carries out multi-hop relay networking transmission using orbiter, orbital vehicle, if
It has counted for multiple detectors by the distributed system Raptor decoding transmission method under orbiter, orbital vehicle to the ground transmitting scene, has mentioned
Gone out the reduction procedure of joint decoding, theory analysis has derived the performance parameter of DSRC scheme and its improvement project, and with it is existing
The distribution of technology entangles the scheme of deleting without rate and carries out emulation comparison, obtained when redundancy reaches 5% 99% it is successfully decoded
Rate.
In the following, this example analyzes the complexity of DSRC scheme: the corresponding volume of the averagely each symbol of system Raptor code
Xor operation number needed for decoding is respectively as follows:In the formula, N table
Show coded identification number, K indicates code length.
It is respectively K for code length in DSRC scheme1And K2Information source W1With information source W2, message sink coding generation N1And N2It is a
Coded identification, the xor operation total degree of cataloged procedure are as follows: Jenctotal=N1·Jenc(N1,K1)+N2·Jenc(N2,K2), relaying
Network-encoding operation only to redundancy encoding semiology analysis, required xor operation number are as follows: JNC=min { (1-Pwr1)·
(N1-K1),(1-Pwr2)·(N2-K2), wherein Pwr1And Pwr2Respectively indicate W1- R sections of links and W2The deletion of-R sections of links is general
Rate.Correspondingly, destination has: Jdectotal=K1·Jdec1+K2·Jdec2=K1·Jdec(M1,K1)+K2·Jdec(M2,K2),
In, M1And M2Indicate that destination D distinguishes received information source W1With information source W2Number of coded symbols, work as K1=K2=K, Pwr1=
Pwr2When=p, then N1≈N2=N, M1≈M2=M.
And for distributed system Raptor code, it only just needs to decode behaviour in the case where system symbol goes out active
Make.Xor operation total degree J relative to coding and decodingenctotalWith the operation total degree J of destinationdectotal, required exclusive or
Number of operations JNCCan almost it ignore, approximate total xor operation number are as follows: Jtotal=(1- (1-p)2K)(Jenctotal+JNC+
Jdectotal)≈2·(1-(1-p)2K)(10·K·N+4.5·K2)。
DSRC scheme has the encoder complexity and O (K of approximately linear O (K) as the above analysis2) decoding it is complicated
Degree.
In the following, this example also proposes improved distributed system Raptor decoding transmission method, i.e., improved DSRC scheme is first
First DSRC scheme decoding failure probability is analyzed.Further analyze DSRC scheme: information source end only generates the volume of fixed quantity
Code sign, relaying by institute received coded identification network code or forwarding guarantee destination data recovery.
It, can be by W firstly the need of the quantity for determining message sink coding symbol1- R sections of links and W2- R sections of links regard two points as
To a communication link, by the experience between Raptor code decoding failure probability and the number of coded symbols m received and code length K
Formula:If then known relaying decoding failure probability ε, utilizes formulaIt can estimate that relaying decoding success rate reaches required received when (1- ε)
Number of coded symbols mth；If predicting W-R sections of link packet drop rate Pwr, then can determine that each information source sends the quantity of coded identification: mth/
(1-Pwr).Theoretically, operation appropriate is carried out using these coded identifications for containing whole raw informations ensure that mesh
End decoding success.
In the case where channel probability of erasure is known in advance, determine information source end send number of coded symbols, then at this time in
After the probability of decoding failure are as follows:Relaying passes through the step
Three kinds of mode selective networks of S202 encode, the lower bound of attainable decoding failure probability be Pfr。
WhenWhen,HaveMeanwhile following shape can be used in destination decoding failure probability
Formula indicates: Pft=1- (1-Pf(M1,K1,δi))·(1-Pf(M2,K2,δi)).Wherein:M1And M2Coming for indicating to receive is self-confident
Source W1, W2System symbol number；M0Indicate that junction network encodes the symbol generated purpose after R-D sections of erasure channels and terminates
The quantity received.Because the uniformly random property of network code, is approximately considered M1=M2；And δi(i=1,2,3) three kinds are respectively indicated
Influence of the selective junction network coding mode to decoding performance.
Analysis is limited based on the performance of and/or tree to DSRC scheme below, it is the most frequently used for the decoding performance analysis of fountain codes
Tool be and/or tree analysis, as shown in figure 4, defining the and/or tree that depth is 2l+1, the depth of root node is defined as
0, the child node of each layer successively drops down.Correspond to input node in the node of even level (0,2,4 ..., 2l), referred to as
" OR " node corresponds to output node in the node of odd-level (1,3,5 ..., 2l-1), referred to as " AND " node.For output degree
It is distributed as the LT code of Ω (x), bi-distribution (1/K, α K) is obeyed in distribution when the side of input node, and when K → ∞, input degree point
Cloth approximation obeys Poisson distribution exp (α (x-1)), and α is the average degree of its input node.It exports side distribution ω (x) and Ω (x) is closed
System are as follows: ω (x)=Ω ' (x)/Ω ' (1).The decoding failure probability of some input node of definition decoding initial stage is
y0, the decoding failure probability y of the node after l decoding iterationlThere is and/or tree theorem formula with the relationship of ω (x) and Ω (x):
If the decoded redundant ratio of destination D is ε, then the average degree Ω ' (1) of α and output node and ε relational expression are as follows:It is writeable are as follows:
For information source W1With information source W2, definition relaying R is with p1Probability forward W1Symbol, with p2Probability forward W2's
Symbol, with p3Probability carry out exclusive or forwarding, and p1+p2+p3=1, then the joint decoding probability of failure formula of destination D are as follows:WithWherein, y0,1
=y0,2=0, p '1=p1/1-p2, p '2=p2/1-p1, p'3=p3/1-p2, p'4=p3/1-p1。
Without loss of generality, if the code length of two information sources and the probability of erasure of link are equal, have:If relaying R receives information source W1With information source W2System symbol be respectively k1And k2, superfluous
Remaining coded identification is respectively n1And n2, relay the probability of erasure of R to destination D as 0, received redundant symbol quantity m, then purpose
The ratio for the coded identification that end D is received is as shown in table 1.
And the distinct symbols probability of relay selection forwarding is as shown in table 2 below.
The pseudorandom dispersion distribution of system Raptor code is as follows: Ω (x)=0.00976658x1+0.459043x2+
0.210964x3+0.113393x4+0.111342x10+0.0798635x11+0.0156279x40。
By formula
WithIf code length K=
100, information source generates 140 coded identifications, then the decoding theory performance of DSRC scheme is as shown in Figure 5.
And/or tree analysis is the classical tool of guidance and the distribution design of verifying degree, as shown in Figure 5, the third mode of this example
The progressive performance of decoding between the second way is close, and the progressive performance of the third mode is best.In addition, being directed to ground
Stand use gaussian elimination decoding algorithm, emulate these three relay process modes Gauss decode lower bound give same property
It can superiority and inferiority trend.
In the following, carrying out specific data analysis, decoding failure probability (Decoding Failure by simulation result
It Rate) is the important indicator for measuring distributed relay correcting and eleting codes performance.Compare the DSRC of proposition and the decoding of SLRC, IRDRS
Can, each decoded redundant parameter point has carried out 104Secondary Monte Carlo simulation.
The performance simulation of DSRC scheme is as follows:
Firstly, simulating decoding performance of the DSRC scheme under different data packet loss.Fig. 6 and Fig. 7 is with code length K=100
For, wherein Fig. 6 Pwr,1=Pwr,2=0.1, emulate different PrdDecoding performance；Fig. 7 is Prd=0.1, emulate different Pwr,
1、Pwr,2Decoding performance；By Fig. 6 and Fig. 7 it is found that whether change source node to relay node packet loss PwrOr change
Packet loss P of the relay node to destination Drd, decoding success rate curve all maintains high consistency, and decoded redundant is close
Decoding failure probability is reduced to 10 when 0.1-4, this just illustrates that DSRC scheme has good robustness, Neng Goushi to link packet drop rate
Answer different channel circumstances.
DSRC scheme and existing SLRC and IRDRS scheme and storage forwarding scheme (BF, Buffer and
Forward comparison emulation), decoding failure probability performance curve is as shown in figure 8, as seen from Figure 8, due to system
The application of Raptor code greatly improved the practicability of DSRC scheme, reduce overhead；And the exclusive or processing relayed, make
It obtains DSRC scheme and improves decoding performance compared to BF.
In step S2 described in the DSRC scheme of this example in the performance simulation of three kinds of modes, setting relaying decoding failure probability
It is 10-4, by formulaThe received coding symbol number of needs, which can be calculated, is
116, respective links packet loss is 5% and 10%, and information source needs to send 122 and 128 coded identifications.It then sets and generates respectively
120/130 and 130/140 message sink coding symbol, relaying are respectively adopted three kinds of exclusive or schemes of DSRC, obtain the property such as Fig. 9
It can curve.Redundancy encoding symbol is only utilized in first way and the second way, increases to 240 with decoded redundant, reaches
Error floor is arrived；And the third mode had both been utilized redundancy encoding symbol and has also utilized system symbol, decoding success rate can become
Nearly Gauss decoding performance circle.
This example is based on the asynchronous store-and-forward mechanism of DTN, passes through same relaying rail for following multiple planet surface exploration devices
Logos and utensils transmits the scene of data to the ground, devises the distributed system Raptor encoding scheme under Y-type network.Firstly, passing through
The joint decoding performance for optimizing destination partially solves the increase of complexity caused by distributed system Raptor code.And believing
Source and relaying R, system structure code word can greatly improve data recovering efficiency, theory analysis and the simulating, verifying side DSRC
For case when probability of erasure is less than 0.2, decoding success rate is with uniformity, and compared with other schemes of the prior art, in redundancy
99% decoding success rate is obtained when reaching 5%.
Future can also further discuss the martian surface detector transmitting scene not reciprocity to relaying orbiter, orbital vehicle link, for
Different business index, different code length carries out the distributed coding research of the mistakes such as non-, to adapt to the diversification of the following deep space communication
Business demand.
The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be said that
Specific implementation of the invention is only limited to these instructions.For those of ordinary skill in the art to which the present invention belongs, exist
Under the premise of not departing from present inventive concept, a number of simple deductions or replacements can also be made, all shall be regarded as belonging to of the invention
Protection scope.
Claims (7)
1. a kind of distributed system Raptor decoding transmission method towards deep space communication, which comprises the following steps:
Step S1 is respectively K to code length1And K2Information source end raw information system Raptor coding and be sent to same
Relaying；
Step S2 relays R for the coded identification from information source end and is respectively stored in buffer area E1With buffer area E2In, then use
DSRC algorithm carries out the rear of data processing and sends to destination；
Step S3, destination D decode the coded identification received；
In the step S2, it includes following sub-step that relaying R, which carries out data processing using DSRC algorithm:
Step S201, forwarding cache area E1,wOr buffer area E2,wIn original symbol, until caching original symbol all forward
It finishes；
Step S202 realizes distributed coding forwarding by relaying R；
In the step S201, if buffer area E1,wOr buffer area E2,wCaching non-empty, then at random from buffer area E1,wOr buffer area
E2,wOne original symbol of middle selection is forwarded, and is finished, is then gone to step until the original symbol of all cachings forwards
S202；
The step S202 in a manner of following three kinds in any one realize distributed coding forwarding: at random from buffer area E1,r
Or buffer area E2,rIt is middle to choose the i.e. storage forwarding of redundancy encoding symbol realization；From buffer area E1,rWith buffer area E2,rIn respectively with
Machine chooses a redundancy encoding symbol and realizes exclusive or forwarding；And at random from buffer area E1,wOr buffer area E2,wIt is middle to choose one
Original symbol, from buffer area E2,rOr buffer area E1,rIn a redundancy encoding symbol randomly selecting, and then realize exclusive or forwarding.
2. the distributed system Raptor decoding transmission method according to claim 1 towards deep space communication, which is characterized in that
In the step S1, the system Raptor cataloged procedure of information source end be by K source symbol C zero padding after, pass through pseudo-random sequence
The intermediate generator matrix G of construction generates L intermediate symbols C ', and meets following formula:Wherein, intermediate generator matrix G includes S LDPC coded identification GLDPC, H
Half coded identification GHalfWith K LT coded identification GLT, L=S+H+K, ISFor S row, S arrange unit matrix, 0S×HIt is arranged for S row, H
Null matrix, IHThe unit matrix arranged for H row, H；S, L, H and K are natural number, represent the row and column of encoder matrix；Centre is accorded with again
Number C ' carry out LT coding generates redundancy encoding packet, and encoder matrix is labeled as RLT；Then original symbol and redundancy encoding are successively sent
Symbol.
3. the distributed system Raptor decoding transmission method according to claim 1 towards deep space communication, which is characterized in that
In the step S1, the information source W of information source end1With information source W2It independently carries out system Raptor coding and then sends it to relaying R
Original symbol and redundancy encoding symbol, and it is respectively stored in buffer area E1With buffer area E2In；Wherein, in step s 2, in described
Pass through buffer area E after R1,wWith buffer area E2,wInformation source W is cached respectively1With information source W2Original symbol, pass through buffer area E1,rIt is gentle
Deposit area E2,rInformation source W is cached respectively1With information source W2Redundancy encoding symbol.
4. the distributed system Raptor decoding transmission method according to claim 3 towards deep space communication, which is characterized in that
In the step S2, information source W1With information source W2Corresponding coded identification is respectively P through probability of erasurewr1And Pwr2Erasure channel arrive
Up to relaying R.
5. the distributed system Raptor decoding transmission method according to any one of claims 1 to 4 towards deep space communication,
It is characterized in that, it is P that coded identification, which is passed through probability of erasure, in the step S3rdR-D section link reach destination D, first
It carries out simplifying processing by confederate matrix shift process, Gauss then is carried out to remaining stopping collection matrix that can not be unitization and is translated
Code.
6. the distributed system Raptor decoding transmission method according to claim 5 towards deep space communication, which is characterized in that
The step S3 includes following sub-step:
Step S301, init state, and elementary row operations are made to decoding matrix and arrange elementary exchange；
Step S302, by row transformation and transformation disappear member realize matrix reduction；
Step S303 realizes that decoding matrix is unitization, and decoding terminates.
7. the distributed system Raptor decoding transmission method according to claim 6 towards deep space communication, which is characterized in that
In the step S301, init state, respectively to piecemeal A1With piecemeal A2Make elementary row operations and the elementary exchange of column simplifies for the first time
Then matrix utilizes obtained I1And I2To RLTMake the member processing that disappears, wherein piecemeal A1For information source W1Corresponding intermediate generator matrix
G1, piecemeal A2For information source W2Corresponding intermediate generator matrix G2, I1For piecemeal A1The resulting unit matrix of abbreviation after progress elementary transformation,
I2For piecemeal A2The resulting unit matrix of abbreviation after progress elementary transformation, RLTIt is random to be carried out to the redundant symbol from two information sources
The generator matrix for the redundant symbol that exclusive or obtains；In the step S302, by U1And U2It is divide into upper part and lower part, it is elementary by row
It converts U1,lowAnd U2,lowBecome upper triangular matrix, and utilizes transformed U1,lowAnd U2,lowTo piecemeal [0, B1、0、B2] make row change
The member that disappears is changed, then suitable row is therefrom selected to add to U1,lowAnd U2,low, obtain C1And C2, wherein U1For to piecemeal A1Carry out the
After the elementary transformation in one stage, the non-zero matrix of the L row of generation, unknown columns；Piecemeal U2For to piecemeal A2Carry out the first stage
After elementary transformation, the non-zero matrix of the L row of generation, unknown columns, U1,lowFor to U1Upper triangular matrix after carrying out elementary transformation,
U2,lowFor to U2Upper triangular matrix after carrying out elementary transformation, piecemeal [0, B1、0、B2] it is non-after carrying out elementary transformation to RLT
Null matrix, piecemeal C1For to U1It carries out elementary transformation and obtains upper triangular matrix U1,lowRemaining submatrix afterwards, piecemeal C2For to U2Into
Elementary row operations obtain upper triangular matrix U2,lowRemaining submatrix afterwards；In the step S303, cast out remaining M-2L row, point
Block is labeled as A11And A22, and it is unitization respectively, decoding terminates, wherein M is the line number of the joint decoding matrix received, and L is
By the code length of the input information source code length K systematic code determined, A11And A22It is the simplified matrix of joint decoding.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110037410A (en) * | 2009-10-06 | 2011-04-13 | 뮤텔테크놀러지 주식회사 | Decoding method for raptor codes using system |
| CN102164026A (en) * | 2011-05-20 | 2011-08-24 | 哈尔滨工业大学深圳研究生院 | Fountain code compiling method based on deep space communication environment |
| CN103297197A (en) * | 2013-06-24 | 2013-09-11 | 哈尔滨工业大学深圳研究生院 | Distributed relay erasure coding method for mobile delay tolerant network |
| CN104219026A (en) * | 2014-09-19 | 2014-12-17 | 西安电子科技大学 | United network code relay transmission method based on 3D (three dimensional) Turbo code |
| CN105262564A (en) * | 2015-09-09 | 2016-01-20 | 哈尔滨工业大学深圳研究生院 | Two-dimensional distribution design method for distributed fountain code |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7669103B2 (en) * | 2006-05-03 | 2010-02-23 | Alcatel-Lucent Usa Inc. | Encoded transmission |
-
2016
- 2016-04-01 CN CN201610202771.8A patent/CN105846958B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110037410A (en) * | 2009-10-06 | 2011-04-13 | 뮤텔테크놀러지 주식회사 | Decoding method for raptor codes using system |
| CN102164026A (en) * | 2011-05-20 | 2011-08-24 | 哈尔滨工业大学深圳研究生院 | Fountain code compiling method based on deep space communication environment |
| CN103297197A (en) * | 2013-06-24 | 2013-09-11 | 哈尔滨工业大学深圳研究生院 | Distributed relay erasure coding method for mobile delay tolerant network |
| CN104219026A (en) * | 2014-09-19 | 2014-12-17 | 西安电子科技大学 | United network code relay transmission method based on 3D (three dimensional) Turbo code |
| CN105262564A (en) * | 2015-09-09 | 2016-01-20 | 哈尔滨工业大学深圳研究生院 | Two-dimensional distribution design method for distributed fountain code |
Non-Patent Citations (1)
| Title |
|---|
| "Network-coded rateless coding scheme in erasure multiple-access relay enable communications";shushi gu et al;《IET Communications》;20130410;538-541 |
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