CN108809521A - A kind of variable length decoding method, device and length variable decoder - Google Patents

A kind of variable length decoding method, device and length variable decoder Download PDF

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CN108809521A
CN108809521A CN201810672004.2A CN201810672004A CN108809521A CN 108809521 A CN108809521 A CN 108809521A CN 201810672004 A CN201810672004 A CN 201810672004A CN 108809521 A CN108809521 A CN 108809521A
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max
equal
absolute value
symbol
transmission time
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CN108809521B (en
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韩赛
马红兵
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China United Network Communications Group Co Ltd
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China United Network Communications Group Co Ltd
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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
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0014—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the source coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0036—Systems modifying transmission characteristics according to link quality, e.g. power backoff arrangements specific to the receiver

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  • Computer Networks & Wireless Communication (AREA)
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  • Compression, Expansion, Code Conversion, And Decoders (AREA)

Abstract

The embodiment provides a kind of variable length decoding method, device and length variable decoders, it is related to field of communication technology, it solves and when configured transmission while being related to absolute value and when symbol is separately encoded in the prior art, when transmission channel has noise jamming, since length variable decoder can not correctly identify that each transmission character corresponds to the position of code word in the bitstream, along with absolute value and symbol correspond to different code books, therefore the problem of accurately can not correctly restore source signal.This method includes determining the first boundary moment l that stage and fixed stage are dissipated in lattice structureds, fixed stage and merging phase the second boundary moment lsc；According to the symbol posterior probability of each symbol code word in the absolute value posterior probability of each absolute value code word in Parameter Estimation Method, first of transmission time absolute value code book and first of transmission time symbol code book, the information transmitted in first of transmission time is determined.The embodiment of the present invention is used for the manufacture of length variable decoder.

Description

A kind of variable length decoding method, device and length variable decoder
Technical field
The present invention relates to a kind of field of communication technology more particularly to variable length decoding method, device and length variable decoders.
Background technology
As shown in Figure 1, in digital communication, for better transmission character in the channel, source encoder is according to default Coding rule source signal is converted into bit stream, bit is then streamed to by source decoder by channel, is then believed Bit stream is converted and is reverted to raw information, wherein coding rule and decoding rule by source decoder according to preset decoding rule It corresponds；In order to obtain better compression effectiveness in the transmission, variable-length encoding (full name in English can be used：variable- Length codes, referred to as：VLCs) the information source character of each quantization is mapped as to the bit combination of different number.Due to VLCs has preferable compression performance, therefore in the communications, VLCs is widely used in image, video and audio coding decoding, than The widely used high-performance Advanced Audio Coder HE-AAC such as in wireless flow media.In the case where transmitting errorless, VLCs Decoder can correctly identify that each character corresponds to the beginning and end position of code word in the bitstream, but error-prone It can not correctly be identified under channel situation, cause serious distortion.And it is once wrong, mistake can accumulate down always.Cause This is for VLCs, with greater need for a kind of good decoder of robustness.
Some researchs are by means of lattice (trellis) representation, in conjunction with some Soft Inform ation soft-decision decoding sides at present Method improves robustness.The advantage of lattice representation is that takes into account all possible transmitted bit sums of a certain transmission time. In traditional lattice representation, the character at all moment is encoded based on same code book, and for some parameters, point Absolute value and symbol (such as the spectral coefficient of the quantization in high-performance Advanced Audio Coding HE-AAC this ginseng of other transmission character Number), it is related to absolute value and symbol and is encoded based on different variable-length encoding code books, therefore in order to use soft-decision decoding method The robustness similar to the spectral coefficient quantified in HE-AAC is improved, needs a kind of decoding based on novel lattice representation Device, more accurately to restore source signal.
It can be seen from the above, working as transmission when configured transmission is related to absolute value simultaneously and symbol is separately encoded in the prior art When channel has noise jamming, since length variable decoder can not correctly identify that each transmission character corresponds to the position of code word in the bitstream Set, along with absolute value and symbol correspond to different code books, how more accurately by source signal correctly restore at For a urgent problem to be solved.
Invention content
A kind of variable length decoding method of the embodiment of the present invention offer, device and length variable decoder, solve in the prior art When configured transmission is related to absolute value simultaneously and symbol is separately encoded, when transmission channel has noise jamming, due to variable length decoding Device can not correctly identify that each transmission character corresponds to the position of code word in the bitstream, along with absolute value and symbol correspond to difference Code book, therefore the problem of accurately source signal correctly can not be restored.
In order to achieve the above objectives, the embodiment of the present invention adopts the following technical scheme that：
First aspect, the embodiment of the present invention provide a kind of variable length decoding method, including：Obtain the word transmitted in bit stream The total B and total bit number R of symbol；Wherein, each character includes absolute value and symbol, and each absolute value and each symbol are single respectively It solely transmits and is encoded with different code books, each absolute value corresponding absolute value code word in absolute value code book, each Symbol corresponding symbol code word in symbol code book, the coding mode that absolute value code book uses is variable-length encoding, symbol code book The coding mode used is variable-length encoding；Wherein, B is the integer more than 0, and R is the integer more than 0；According in absolute value code book The minimum number bits N that absolute value code word occupiesminWith maximum number bits Nmax, symbol code word occupies in symbol code book minimum bit The total B and total bit number R of number x and maximum number bits t, character are determined and are dissipated the of stage and fixed stage in lattice structure One boundary moment lds, fixed stage and merging phase the second boundary moment lsc；According to the first boundary moment ldsAnd the second boundary Moment lsc, determine the first set of the corresponding state of first of transmission time absolute value and the second collection of the corresponding state of symbol It closes；Wherein, the minimum value of first of transmission time first set is Vstart, the maximum value of first of transmission time first set is Vend, the minimum value of first of transmission time second set is V'start, the maximum value of first of transmission time second set is V'end； Wherein, first set includes at least one possible state, and the state in first set refers to have been passed by the end of the current transmission moment The total bit number of absolute value, second set include at least one possible state, and the state in second set refers to by the end of current Transmission time has passed the total bit number of symbol, includes in the corresponding first set of each transmission time in the diverging stage The total quantity of state shows a rising trend, the state for including in the corresponding first set of each transmission time in the fixed stage Total quantity remain unchanged, the sum for the state for including in the corresponding first set of each transmission time in merging phase Amount gradually decreases, and until reaching known character sum B and total number of bits R, diverging stage, fixed stage or merging phase are only It is distinguished for absolute value；Obtain prior probability and bit error probability；The transmitted according to absolute value code book, each transmission time The V of one setstart, first set Vend, prior probability and bit error probability, determine in each transmission time absolute value code The absolute value posterior probability of each absolute value code word in this；The second set transmitted according to symbol code book, each transmission time V'start, second set V'end, prior probability and bit error probability, determine each in each transmission time symbol code book The symbol posterior probability of symbol code word；According in Parameter Estimation Method, first of transmission time absolute value code book each absolute value it is exhausted To the symbol posterior probability of each symbol in value posterior probability and first of transmission time symbol code book, first of transmission time is determined The information of middle transmission.
Optionally, the minimum number bits N occupied according to absolute value code word in absolute value code bookminWith maximum number bits Nmax、 Minimum number bits x and maximum number bits t, the total B of the character and total bit number R that symbol code word occupies in symbol code book are determined The first boundary moment l in stage and fixed stage is dissipated in lattice structureds, fixed stage and merging phase the second boundary moment lsc, including：The minimum number bits N occupied according to absolute value code word in absolute value code bookminWith maximum number bits Nmax, symbol code book Minimum number bits x and maximum number bits t, the total B of the character and total bit number R that middle symbol code word occupies, determine lattice structure The minimum number bits N' of the practical code word used of middle absolute valueminWith the maximum of the practical code word used of absolute value in lattice structure Bit number N'max, intermediate variable R' and intermediate variable l'；Wherein,
N'min=max (R-Nmax×(B-1)-t×B,Nmin)；
N'max=min (R-Nmin×(B-1),Nmax)；
Wherein, the smallest positive integral value that R' is the R for meeting variable formula ", variable formula are：
R " fromStart, constantly add 1, as R and " stops adding 1 when meeting the variable formula；
According to determining minimum number bits N'min, maximum number bits N'max, intermediate variable R' and intermediate variable l', determine lattice The second boundary moment l of stage and merging phase is fixed in type structurescAnd the sum for the state in first set including is most Big value qmax；According to qmax, determine the first boundary moment l that stage and fixed stage are dissipated in lattice structuredsAnd second set The maximum value of the sum for the state for including inside is equal to qmax+t。
Optionally, according to determining minimum number bits N'min, maximum number bits N'max, intermediate variable R' and intermediate variable L' determines the second boundary moment l in fixed stage and merging phasescAnd the maximum of the sum for the state in first set including Value qmax, including：
When determining R≤NminWhen × B+t, the second boundary moment lscEqual to B, maximum value qmaxEqual to R-N'min×B+1；
When determining R≤Nmax×(B-l')+NminWhen × l'+t × (B-l'+1), the second boundary moment lscIt is equal toMaximum value qmaxEqual to R-N'min×B+1；
When determining R < R', the second boundary moment lscIt is equal toMaximum value qmaxIt is equal to (N'max-N'min+t)×(B-lsc)+t+1；
When determining R < NmaxWhen × B+t × (B-1), the second boundary moment lscIt is equal toMaximum value qmax Equal to (N'max+t)×B-R+1；
When determining R >=NmaxWhen × B+t × (B-1), the second boundary moment lscEqual to B, maximum value qmaxEqual to (N'max+t) ×B-R+1；
According to qmax, determine the first boundary moment l that stage and fixed stage are dissipated in lattice structuredsAnd second set The maximum value of the sum for the state for including inside is equal to qmax+ t, including：
According to maximum value qmax, determine the first boundary moment ldsIt is equal toThe shape for including in second set The maximum value of the sum of state is equal to qmax+t。
Optionally, according to the first boundary moment ldsWith the second boundary moment lsc, determine first of transmission time absolute value pair The second set of the corresponding state of first set and symbol for the state answered, including：
When determine transmission time l be less than or equal to the first boundary moment ldsWhen, determine the V of first setstartEqual to N'min × l, the V of first setendEqual to N'max× l+t × (l-1), the V' of second setstartEqual to max (Vstart,R-N'max× (B-l)-t × (B-l)), the V' of second setendEqual to min (Vend+t,R-N'min×(B-l))；
When determine transmission time l be more than the first boundary moment ldsAnd transmission time l is less than or equal to the second boundary moment lsc When, determine the V of first setstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the V of first setend Equal to Vstart+qmax- 1, the V' of second setstartEqual to max (Vstart,R-N'max× (B-l)-t × (B-l)), second set V'endEqual to min (Vend+t,R-N'min×(B-l))；
When determine transmission time l be more than the second boundary moment lscWhen, determine the V of first setstartEqual to max (N'min× l,R-t×(B-l+1)-N'max× (B-l)), the V of first setendEqual to R-N'min× (B-l), the V' of second setstartDeng In min (Vstart+t,R-t×(B-l)-N'max× (B-l)), the V' of second setendEqual to R-N'min×(B-l)。
Second aspect, the embodiment of the present invention provide a kind of variable length decoding device, including：Acquisition module, for obtaining ratio The total B and total bit number R of the character transmitted in spy's stream；Wherein, each character includes absolute value and symbol, each absolute value and Each symbol is individually transmitted and is encoded with different code books, and each absolute value corresponds to one absolutely in absolute value code book To being worth code word, each symbol corresponding symbol code word in symbol code book, the coding mode that absolute value code book uses is elongated Coding, the coding mode that symbol code book uses is variable-length encoding；Wherein, B is the integer more than 0, and R is the integer more than 0；Processing Module, the minimum number bits N for being occupied according to absolute value code word in absolute value code bookminWith maximum number bits Nmax, symbolic code The total B and acquisition mould of the character of symbol code word occupies in this minimum number bits x and maximum number bits t, acquisition module acquisition The total bit number R that block obtains determines the first boundary moment l that stage and fixed stage are dissipated in lattice structureds, fixed stage with The second boundary moment l of merging phasesc；Processing module is additionally operable to according to the first boundary moment ldsWith the second boundary moment lsc, Determine the first set of the corresponding state of first of transmission time absolute value and the second set of the corresponding state of symbol；Wherein, The minimum value of first of transmission time first set is Vstart, the maximum value of first of transmission time first set is Vend, first The minimum value of transmission time second set is V'start, the maximum value of first of transmission time second set is V'end；Wherein, first Set includes at least one possible state, and the state in first set refers to has passed the total of absolute value by the end of the current transmission moment Bit number, second set include at least one possible state, and the state in second set refers to be passed by the end of the current transmission moment The total bit number of complete symbol, the sum for the state for including in the corresponding first set of each transmission time in the diverging stage Amount shows a rising trend, and the total quantity for the state for including in the corresponding first set of each transmission time in the fixed stage is protected The total quantity for holding constant, to include in the corresponding first set of each transmission time in merging phase state gradually subtracts Few, until reaching known character sum B and total number of bits R, diverging stage, fixed stage or merging phase are only for absolute Value is distinguished；Acquisition module is additionally operable to obtain prior probability and bit error probability；Processing module is additionally operable to according to absolute value code Originally, the V of the first set of each transmission time transmissionstart, first set Vend, acquisition module obtain prior probability and obtain The bit error probability that modulus block obtains determines the absolute value of absolute value code word each in each transmission time absolute value code book Posterior probability；Processing module is additionally operable to the V' for the second set transmitted according to symbol code book, each transmission timestart, second collection The V' of conjunctionend, acquisition module obtain prior probability and acquisition module obtain bit error probability, determine in each transmission Carve the symbol posterior probability of each symbol code word in symbol code book；Processing module is additionally operable to according to Parameter Estimation Method, first of biography Each symbol in the absolute value posterior probability of each absolute value and first of transmission time symbol code book in defeated moment absolute value code book Symbol posterior probability, determine the information transmitted in first of transmission time.
Optionally, processing module is specifically used for the minimum number bits N occupied according to absolute value code word in absolute value code bookmin With maximum number bits Nmax, symbol code word occupies in symbol code book minimum number bits x and maximum number bits t, acquisition module obtain Character total B and acquisition module obtain total bit number R, determine that the practical code word used of absolute value is most in lattice structure Small bit number N'minWith the maximum number bits N' of the practical code word used of absolute value in lattice structuremax, intermediate variable R' and centre Variable l'；Wherein,
N'min=max (R-Nmax×(B-1)-t×B,Nmin)；
N'max=min (R-Nmin×(B-1),Nmax)；
Wherein, the smallest positive integral value that R' is the R for meeting variable formula ", variable formula are：
R " fromStart, constantly add 1, as R and " stops adding 1 when meeting the variable formula；
Processing module is specifically used for according to determining minimum number bits N'min, maximum number bits N'max, intermediate variable R' and Intermediate variable l' determines the second boundary moment l that stage and merging phase are fixed in lattice structurescAnd include in first set State sum maximum value qmax；Processing module is specifically used for according to qmax, determine and dissipate stage and fixation in lattice structure The first boundary moment l in stagedsAnd the maximum value of the sum for the state in second set including is equal to qmax+t。
Optionally, processing module is specifically used for as determining R≤NminWhen × B+t, the second boundary moment lscIt is maximum equal to B Value qmaxEqual to R-N'min×B+1；
Processing module is specifically used for as determining R≤Nmax×(B-l')+NminWhen × l'+t × (B-l'+1), the second boundary Moment lscIt is equal toMaximum value qmaxEqual to R-N'min×B+1；
Processing module, specifically for when determining R < R', the second boundary moment lscIt is equal to Maximum value qmaxEqual to (N'max-N'min+t)×(B-lsc)+t+1；
Processing module is specifically used for as determining R < NmaxWhen × B+t × (B-1), the second boundary moment lscIt is equal toMaximum value qmaxEqual to (N'max+t)×B-R+1；
Processing module is specifically used for as determining R >=NmaxWhen × B+t × (B-1), the second boundary moment lscIt is maximum equal to B Value qmaxEqual to (N'max+t)×B-R+1；
Processing module is specifically used for according to maximum value qmax, determine the first boundary moment ldsIt is equal to The maximum value of the sum for the state for including in second set is equal to qmax+t。
Optionally, processing module is specifically used for being less than or equal to the first boundary moment l as determining transmission time ldsWhen, really Determine the V of first setstartEqual to N'min× l, the V of first setendEqual to N'max× l+t × (l-1), second set V'startEqual to max (Vstart,R-N'max× (B-l)-t × (B-l)), the V' of second setendEqual to min (Vend+t,R-N'min ×(B-l))；
Processing module is specifically used for being more than the first boundary moment l as determining transmission time ldsAnd transmission time l is less than or waits In the second boundary moment lscWhen, determine the V of first setstartEqual to max (N'min×l,R-t×(B-l+1)-N'max×(B- L)), the V of first setendEqual to Vstart+qmax- 1, the V' of second setstartEqual to max (Vstart,R-N'max×(B-l)-t × (B-l)), the V' of second setendEqual to min (Vend+t,R-N'min×(B-l))；
Processing module is specifically used for being more than the second boundary moment l as determining transmission time lscWhen, determine first set VstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the V of first setendEqual to R-N'min× (B-l), The V' of second setstartEqual to min (Vstart+t,R-t×(B-l)-N'max× (B-l)), the V' of second setendEqual to R- N'min×(B-l)。
The third aspect, the embodiment of the present invention provide a kind of length variable decoder, include any one provided such as second aspect Variable length decoding device.
The embodiment of the present invention provides a kind of variable length decoding method, passes through the ratio in the total B and bit stream of transmission character Special sum R, the minimum number bits N of absolute value code word in absolute value code bookminWith maximum number bits Nmax, symbolic code in symbol code book The minimum number bits x and maximum number bits t of word, determine boundary moment ldsAnd lsc, may thereby determine that the character received belongs to Which in stage；And according to the V for the first set that absolute value code book, each transmission time transmitstart, first set Vend, first Probability and bit error probability are tested, determines the absolute value posteriority of absolute value code word each in each transmission time absolute value code book Probability；According to the V' for the second set that symbol code book, each transmission time transmitstart, second set V'end, prior probability and Bit error probability determines the symbol posterior probability of symbol code word each in each transmission time symbol code book；According to parameter The absolute value posterior probability and first of transmission time symbol of each absolute value in the estimation technique, first of transmission time absolute value code book The symbol posterior probability of each symbol, determines the information transmitted in first of transmission time in code book；Since reception can be told To bit stream in each possible initial state of character corresponding bit stream therefore can more accurately know each transmission The information of moment transmission solves and when configured transmission while being related to absolute value in the prior art and when symbol is separately encoded, working as biography When defeated channel has noise jamming, since length variable decoder can not correctly not identify that each transmission character corresponds to code word in the bitstream Position, along with absolute value and symbol correspond to different code books, therefore the problem of accurately can not correctly restore source signal.
Description of the drawings
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below There is attached drawing needed in technology description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with Obtain other attached drawings according to these attached drawings.
Fig. 1 is the configuration diagram of telecommunication transmission system in the prior art；
Fig. 2 provides a kind of flow diagram of variable length decoding method for the embodiment of the present invention；
Fig. 3-a provide a kind of one of schematic diagram of the lattice representation of variable length decoding method for the embodiment of the present invention；
Fig. 3-b provide the two of a kind of schematic diagram of the lattice representation of variable length decoding method for the embodiment of the present invention；
Fig. 3-c provide the three of a kind of schematic diagram of the lattice representation of variable length decoding method for the embodiment of the present invention；
Fig. 3-d provide the four of a kind of schematic diagram of the lattice representation of variable length decoding method for the embodiment of the present invention；
Fig. 3-e provide the five of a kind of schematic diagram of the lattice representation of variable length decoding method for the embodiment of the present invention；
Fig. 4 provides a kind of structural schematic diagram of variable length decoding device for the embodiment of the present invention.
Reference numeral：
Variable length decoding device -10；
Acquisition module -101；Processing module -102.
Specific implementation mode
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete Site preparation describes, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other Embodiment shall fall within the protection scope of the present invention.
For the ease of clearly describing the technical solution of the embodiment of the present invention, in an embodiment of the present invention, use " the One ", the printed words such as " second " distinguish function and the essentially identical identical entry of effect or similar item, and those skilled in the art can To understand that the printed words such as " first ", " second " are not to be defined to quantity and execution order.
It should be noted that in the embodiment of the present invention, " illustrative " or " such as " etc. words make example, example for indicating Card or explanation.Be described as in the embodiment of the present invention " illustrative " or " such as " any embodiment or design scheme do not answer It is interpreted than other embodiments or design scheme more preferably or more advantage.Specifically, " illustrative " or " example are used Such as " word is intended to that related notion is presented in specific ways.
In actual application, each transmission time l, it is possible to transmit absolute value, it is also possible to transmit symbol；In view of elder generation It passes absolute value and passes symbol again, it is two transmission node l that the present invention, which defines each transmission time l to be divided to,c(i.e. lcEqual to 1,2 ..., 2 × B})；Wherein, odd number lcRepresent the absolute value of the character received, even number lcThe symbol for receiving the character is represented, specifically Realization process is as follows：
Since each character includes absolute value and symbol, so we assume that the absolute value of the spectral coefficient of quantization and corresponding Symbol share the same transmission time l and be equal to { 1,2,3,4 }, i.e., a character is transmitted in each transmission time l；Such as Fig. 3-a Shown in Fig. 3-e, abscissa illustrates transmission node lc, ordinate qlcIllustrate the state of each transmission node, absolute value code The bit number that word occupies includes 1,2 or 3 three kind of (i.e. Nmin=1, Nmax=3), the bit number of symbol code word occupancy includes：0,1 Or 2 three kinds (i.e. x=0, t=2), work as lcFor odd number when (lc=2 × l-1), all possible states composition of the transmission node is exhausted To the first set of value；Work as lcFor even number when (lc=2 × l), the second collection of all possible states composition symbol of the transmission node It closes, i.e. when l is equal to 1, expression transmits the 1st character；When l is equal to 2, expression transmits the 2nd character；When l is equal to 3, indicate Transmit the 3rd character；When l is equal to 4, expression transmits the 4th character；Since each transmission time l includes that two transmission save Point lc, therefore in each transmission time l, if transmission node lcWhat is transmitted is the absolute value of character, then in lc+ 1 transmission section What point transmitted is the symbol of the character.
It should be noted that each character transmitted in bit stream might not can carry symbol, such as character of transmission Just without symbol when being 0, i.e., the symbol that 0 absolute value is 0,0 is empty, need not transmit any bit；Due in symbol code book Symbol code word occupy bit number constant interval be [x, t], it is contemplated that in actual transmission process there are symbol be it is empty Situation, i.e. x are equal to 0, and when x is equal to 0, the character only takes up the corresponding bit number of absolute value code word in the bitstream；Therefore, it examines Consider general scenario, in the variable length decoding method that the embodiment of the present invention provides, the variation zone for the bit number that symbol code word occupies Between be [0, t], i.e. x be equal to 0.
Specifically, from odd number lc(absolute value) arrives even number lc(symbol), the state change range in lattice structure can be from x to t (wherein, 0) x is equal to；Opposite, from even number lc(symbol) arrives odd number lc(absolute value), the state change range in lattice structure can From N'minTo N'max；Illustratively, when the l as shown in Fig. 3-a is equal to 1, including：lcEqual to 1 and lcEqual to 2 two transmission nodes；Its In, l is equal to 1 and indicates to transmit first character, lcEqual to the absolute value that 1 expression transmits first character, lcIt is indicated equal to 2 The symbol of first character is transmitted, it is each in being equal to 1 that l is equal to the meaning of each transmission node and l during 2, l is equal to 3 and l equal to 4 The meaning of a transmission node is identical, and details are not described herein again.
Specifically, passing absolute value (i.e. odd number l again in view of first passing symbolcRepresent the symbol of the character received, even number lcRepresent the absolute value for receiving the character), symbol (i.e. odd number l is passed again with absolute value is first passedcRepresent the character received Absolute value, even number lcRepresent and receive the symbol of the character) realization method it is similar, details are not described herein again.
Embodiment one
The embodiment of the present invention provides a kind of variable length decoding method, includes as shown in Figure 2：
S101, the total B and total bit number R for obtaining the character transmitted in bit stream；Wherein, each character includes absolute value And symbol, each absolute value and each symbol are individually transmitted and are encoded with different code books, each absolute value is exhausted To a corresponding absolute value code word in value code book, each symbol a corresponding symbol code word, absolute value code book in symbol code book The coding mode used is variable-length encoding, and the coding mode that symbol code book uses is variable-length encoding；Wherein, B is whole more than 0 Number, R are the integer more than 0.
It should be noted that in actual application, as shown in Figure 1, source encoder is according to absolute value code book and symbol Source signal is converted to the bit stream indicated with 0 or 1 by code book.
Illustratively, it is respectively+5, -6 ,+1.2 and 0 to assume that source signal needs 4 characters of transmission ,+5 absolute value pair It is y to answer the code word in absolute value code book(0)=(1,0,1), it is y that -6 absolute value, which corresponds to the code word in absolute value code book,(1)= (0), it is y that+1.2 absolute value, which corresponds to the code word in absolute value code book,(2)=(1,1), 0 absolute value correspond in absolute value code book Code word be y(3)The symbol code word of=(1,0,0), the corresponding symbol code book of "+" number is H(0)=(0), the corresponding symbol code book of "-" number Symbol code word be H(1)=(0,1), the symbol code word of symbol code book is H when without sign bit(2)=().It (needs to illustrate It is, when the character of transmission is 0, since the absolute value of character 0 is in 0, and 0 not tape symbol itself, i.e., the bit number of 0 symbol It is 0, therefore 0 sign bit number is not take up in actual transmission process).
By+5, -6 ,+1.2 and 0, after being converted to bit stream, corresponding bit stream can be expressed as：1010001110100 (the total B of the character of transmission is equal to 4,13) total bit number R is equal to；When the bit stream transmits in transmission channel, decoding apparatus When receiving the bit stream, need to know any one transmission time, each character corresponding initial position and end in the bitstream Stop bit is set, and corresponding information could be restored.
S102, the minimum number bits N occupied according to absolute value code word in absolute value code bookminWith maximum number bits Nmax, symbol Minimum number bits x and maximum number bits t, the total B of the character and total bit number R that symbol code word occupies in number sheet, determine lattice The first boundary moment l in stage and fixed stage is dissipated in type structureds, fixed stage and merging phase the second boundary moment lsc。
Optionally, in the variable length decoding method that the embodiment of the present invention provides, according to absolute value code word in absolute value code book The minimum number bits N of occupancyminWith maximum number bits Nmax, symbol code word occupies in symbol code book minimum number bits x and maximum Bit number t, the total B of character and total bit number R determine the first boundary moment that stage and fixed stage are dissipated in lattice structure lds, fixed stage and merging phase the second boundary moment lsc, including：
S1020, the minimum number bits N occupied according to absolute value code word in absolute value code bookminWith maximum number bits Nmax, symbol Minimum number bits x and maximum number bits t, the total B of the character and total bit number R that symbol code word occupies in number sheet, determine lattice The minimum number bits N' of the practical code word used of absolute value in type structureminWith the practical code word used of absolute value in lattice structure Maximum number bits N'max, intermediate variable R' and intermediate variable l'；Wherein,
N'min=max (R-Nmax×(B-1)-t×B,Nmin)；
N'max=min (R-Nmin×(B-1),Nmax)；
Wherein, the smallest positive integral value that R' is the R for meeting variable formula ", variable formula are：
R " fromStart, constantly add 1, as R and " stops adding 1 when meeting the variable formula.
S1021, according to determining minimum number bits N'min, maximum number bits N'max, intermediate variable R' and intermediate variable l', Determine the second boundary moment l that stage and merging phase are fixed in lattice structurescAnd the state in first set including is total Several maximum value qmax。
S1022, according to qmax, determine the first boundary moment l that stage and fixed stage are dissipated in lattice structuredsAnd the The maximum value of the sum for the state for including in two set is equal to qmax+t。
Optionally, S1021 includes in the variable length decoding method that the embodiment of the present invention provides：According to determining minimum bit Number N'min, maximum number bits N'max, intermediate variable R' and intermediate variable l', determine the second boundary in fixed stage and merging phase Moment lscAnd the maximum value q of the sum for the state in first set includingmax, including：
S1021-1, when determining R≤NminWhen × B+t, the second boundary moment lscEqual to B, maximum value qmaxEqual to R-N'min× B+1；
S1021-2, when determining R≤Nmax×(B-l')+NminWhen × l'+t × (B-l'+1), the second boundary moment lscIt is equal toMaximum value qmaxEqual to R-N'min×B+1；
S1021-3, when determining R < R', the second boundary moment lscIt is equal toMaximum value qmax Equal to (N'max-N'min+t)×(B-lsc)+t+1；
S1021-4, when determining R < NmaxWhen × B+t × (B-1), the second boundary moment lscIt is equal to Maximum value qmaxEqual to (N'max+t)×B-R+1；
S1021-5, when determining R >=NmaxWhen × B+t × (B-1), the second boundary moment lscEqual to B, maximum value qmaxIt is equal to (N'max+t)×B-R+1；
S1022, according to qmax, determine the first boundary moment l that stage and fixed stage are dissipated in lattice structuredsAnd the The maximum value of the sum for the state for including in two set is equal to qmax+ t, including：
S1022-1, according to maximum value qmax, determine the first boundary moment ldsIt is equal toIn second set Including state sum maximum value be equal to qmax+t。
S103, according to the first boundary moment ldsWith the second boundary moment lsc, determine that first of transmission time absolute value corresponds to State first set and the corresponding state of symbol second set；Wherein, the minimum of first of transmission time first set Value is Vstart, the maximum value of first of transmission time first set is Vend, the minimum value of first of transmission time second set is V'start, the maximum value of first of transmission time second set is V'end；Wherein, first set includes at least one possible shape State, the state in first set refers to has passed the total bit number of absolute value by the end of the current transmission moment, and second set includes at least One possible state, the state in second set refers to has passed the total bit number of symbol by the end of the current transmission moment, is located at hair The total quantity for the state for including in the corresponding first set of each transmission time in the stage of dissipating shows a rising trend, and is located at Fixed-order The total quantity for the state for including in the corresponding first set of each transmission time in section remains unchanged, and is located in merging phase The total quantity for the state for including in the corresponding first set of each transmission time gradually decreases, until reaching known character sum B and total number of bits R, diverging stage, fixed stage or merging phase are distinguished only for absolute value.
Specifically, in actual application, according to traditional lattice representation, present applicant proposes a kind of new lattice tables Show method, can be directed to absolute value and symbol has the VLCs of different code books.
Illustratively, 4 characters are transmitted with t=2, the absolute value representation of each character is y in absolute value code book(0)= (1,0,1), y(1)=(0), y(2)=(1,1), y(3)=(1,0,0), the symbolic indication of each character is H in symbol code book(0)= (0), H(1)=(0,1), H(2)It is illustrated for=()；Wherein, the bit number that absolute value code word occupies includes 1,2 or 3 three Kind, the bit number that symbol code word occupies includes：0,1 or 2 three kind, 5 kinds of differences are set forth as shown in Fig. 3-a to Fig. 3-e The corresponding lattice tables of total bit number R (R=6, R=10, R=13, R=17 and R=18).
Specifically, it was found that the minimum number bits that absolute value code word occupies in absolute value code book in actual application NminWith maximum number bits Nmax, symbol code word occupies in symbol code book minimum number bits x and maximum number bits t, character it is total The minimum number bits N' of number B and total bit number R and the practical absolute value code word used of absolute value in lattice structureminWith lattice knot The maximum number bits N' of the practical absolute value code word used of absolute value in structuremaxThere are following relationships：
N'min=max (R-Nmax×(B-1)-t×B,Nmin)；
N'max=min (R-Nmin×(B-1),Nmax)；
Wherein, NminAnd NmaxThe minimum value for having respectively represented all code words in code book (is N in this examplemin=1) and maximum value (it is N in this examplemax=3).
Correspondingly, for each transmission time, the stage is dissipated, fixed stage and merging phase are only according to the transmission section of odd number Point lcCorresponding status number, the transmission node l without considering even numbercCorresponding status number.That is, the first boundary moment lds (diverging stage and fixed stage) and the second boundary moment lsc(fixed stage and merging phase) be about transmission time l (without It is transmission node lc)。
Illustratively, it is illustrated so that the total bit number of transmission is R=10 as an example as shown in Fig. 3-b, concrete implementation mistake Journey is as follows：
When l is equal to 1 and lcWhen equal to 1, the absolute value of first character is transmitted, what the absolute value code word that may be transmitted occupied Bit number includes 1,2 or 3；By the end of current transmission node lcWhen equal to 1, the total number of bits transmitted in bit stream may be 1, 2 or 3；Therefore, lcWhen equal to 1, the first set of absolute value corresponding states is { 1,2,3 }, the i.e. V of first setstartIt is 1, The V of first setendIt is 3.
When l is equal to 1 and lcWhen equal to 2, the symbol of first character is transmitted, the bit that the symbol code word that may be transmitted occupies Number includes 0,1 or 2；By the end of current transmission node lcWhen equal to 2, the total number of bits transmitted in bit stream may be 1,2,3, 4 or 5；Therefore, lcWhen equal to 2, the second set of symbol corresponding states is { 1,2,3,4,5 }, the i.e. V' of second setstartFor 1, the V' of second setendIt is 5.
When l is equal to 2 and lcWhen equal to 3, the absolute value of second character is transmitted, what the absolute value code word that may be transmitted occupied Bit number includes 1,2 or 3；By the end of current transmission node lcWhen equal to 3, the total number of bits transmitted in bit stream may be 2, 3,4,5,6,7 or 8；Therefore, lcWhen equal to 3, the first set of absolute value corresponding states is { 2,3,4,5,6,7,8 }, i.e., the The V of one setstartIt is 2, the V of first setendIt is 8.
When l is equal to 2 and lcWhen equal to 4, the symbol of second character is transmitted, the bit that the symbol code word that may be transmitted occupies Number includes 0,1 or 2；By the end of current transmission node lcWhen equal to 4, the total number of bits transmitted in bit stream may be 2,3,4, 5,6,7 or 8；Therefore, lcWhen equal to 4, the second set of symbol corresponding states is { 2,3,4,5,6,7,8 }, i.e. second set V'startIt is 2, the V' of second setendIt is 8.
When l is equal to 3 and lcWhen equal to 5, the absolute value of third character is transmitted, what the absolute value code word that may be transmitted occupied Bit number includes 1,2 or 3；By the end of current transmission node lcWhen equal to 5, the total number of bits transmitted in bit stream may be 3, 4,5,6,7,8 or 9；Therefore, lcWhen equal to 5, the first set of absolute value corresponding states is { 3,4,5,6,7,8,9 }, i.e., the The V of one setstartIt is 3, the V of first setendIt is 9.
When l is equal to 3 and lcWhen equal to 6, the symbol of third character is transmitted, the bit that the symbol code word that may be transmitted occupies Number includes 0,1 or 2；By the end of current transmission node lcWhen equal to 6, the total number of bits transmitted in bit stream may be 5,6,7, 8 or 9；Therefore, lcWhen equal to 6, the second set of symbol corresponding states is { 5,6,7,8,9 }, the i.e. V' of second setstartFor 5, the V' of second setendIt is 9.
When l is equal to 4 and lcWhen equal to 7, the absolute value of the 4th character is transmitted, what the absolute value code word that may be transmitted occupied Bit number includes 1,2 or 3；By the end of current transmission node lcWhen equal to 7, the total number of bits transmitted in bit stream may be 8, 9 or 10；Therefore, lcWhen equal to 7, the first set of absolute value corresponding states is { 8,9,10 }, the i.e. V of first setstartFor 8, the V of first setendIt is 10.
When l is equal to 4 and lcWhen equal to 8, the symbol of the 4th character is transmitted, the bit that the symbol code word that may be transmitted occupies Number includes 0,1 or 2；By the end of current transmission node lcWhen equal to 8, the total number of bits transmitted in bit stream may be 10；Cause This, lcWhen equal to 8, the second set of symbol corresponding states is { 10 }, the i.e. V' of second setstartIt is 10, second set V'endIt is 10.
It can be seen from the above, lcThe first set of absolute value corresponding states is { 1,2,3 }, l when equal to 1cAbsolute value when equal to 3 The first set of corresponding states is { 2,3,4,5,6,7,8 }, lcWhen equal to 5 the first set of absolute value corresponding states be 3,4, 5,6,7,8,9 }, lcThe first set of absolute value corresponding states is { 8,9,10 } when equal to 7；Therefore, lcFirst set when equal to 1 The status number for including inside is 3, lcThe status number for including in first set when equal to 3 is 7, lcInclude in first set when equal to 5 Status number is 7, lcThe status number for including in first set when equal to 7 is 3；Due to from lcL is arrived equal to 1cIt is each transmitted in equal to 3 The status number for including in the first set of node gradually increases, therefore lcEqual to 1, lcEqual to 2 and lcEqual to 3 in diverging rank Section；Due to from lcL is arrived equal to 3cThe status number for including in the first set of each transmission node in equal to 5 remains unchanged, therefore lc Equal to 3, lcEqual to 4 and lcEqual to 5 in the fixed stage；Due to from lcL is arrived equal to 5cThe of each transmission node in equal to 7 The status number for including in one set is gradually reduced, therefore lcEqual to 5, lcEqual to 6 and lcMerging phase is in equal to 7；Due to, In lcEqual to 1, lcEqual to 3, lcEqual to 5 and lcThe maximum for the status number for including in the first set of each transmission node in equal to 7 Value is 7, therefore qmaxEqual to 7.
It should be noted that in practical applications as shown in Fig. 3-a, by the end of lcThe ratio transmitted in bit stream when equal to 5 The maximum value of special sum is 9, and total transmitted bit number is R=10, i.e., by the end of lcThe ratio transmitted in bit stream when equal to 8 Special sum is 10；In view of from lcL is arrived equal to 5cIn equal to 7 each transmission node should at least 1 bit transfer, therefore, by the end of lcWhen equal to 5, the total number of bits transmitted in bit stream can not possibly be more than 9；In another example by the end of lcWhen equal to 7, passed in bit stream The maximum value of defeated total number of bits is 10, and total transmitted bit number is R=10, i.e., by the end of lcWhen equal to 8 in bit stream The total number of bits of transmission is 10；In view of from lcL is arrived equal to 7cTransmission node can be without bit transfer in equal to 8；Therefore, end To lcThe total number of bits transmitted in bit stream when equal to 7 can be 10.
Specifically, since the maximum value of the sum for the state for including in second set is equal to qmax+ t, and in above-described embodiment T is equal to 2, therefore the maximum value of the sum for the state for including in second set is equal to qmax+2。
Specifically, the V of the R=6 either first sets of R=13 or R=17 or R=18start, first set Vend、 The V' of second setstart, second set V'end、qmax, the diverging stage, fixed stage and merging phase determination process and R =10 is similar, and details are not described herein again.
Optionally, in the variable length decoding method that the embodiment of the present invention provides, according to the first boundary moment ldsWith the second side Boundary moment lsc, determine the corresponding state of first of transmission time absolute value first set and the corresponding state of symbol second Set, including：
S1030, when determine transmission time l be less than or equal to the first boundary moment ldsWhen, determine the V of first setstartDeng In N'min× l, the V of first setendEqual to N'max× l+t × (l-1), the V' of second setstartEqual to max (Vstart,R- N'max× (B-l)-t × (B-l)), the V' of second setendEqual to min (Vend+t,R-N'min×(B-l))；
S1031, when determine transmission time l be more than the first boundary moment ldsAnd transmission time l is less than or equal to the second boundary Moment lscWhen, determine the V of first setstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the first collection The V of conjunctionendEqual to Vstart+qmax- 1, the V' of second setstartEqual to max (Vstart,R-N'max× (B-l)-t × (B-l)), the The V' of two setendEqual to min (Vend+t,R-N'min×(B-l))；
S1032, when determine transmission time l be more than the second boundary moment lscWhen, determine the V of first setstartEqual to max (N'min× l, (B-l+1)-× (B-l)), the V of first setendEqual to R-N'min× (B-l), the V' of second setstartIt is equal to min(Vstart+t,R-t×(B-l)-N'max× (B-l)), the V' of second setendEqual to R-N'min×(B-l)。
S104, prior probability and bit error probability are obtained.
It should be noted that the calculation of prior probability and bit error probability is similarly to the prior art, herein no longer It repeats.
The V of S105, the first set transmitted according to absolute value code book, each transmission timestart, first set Vend, first Probability and bit error probability are tested, determines the absolute value posteriority of absolute value code word each in each transmission time absolute value code book Probability.
The V' of S106, the second set transmitted according to symbol code book, each transmission timestart, second set V'end, first Probability and bit error probability are tested, determines the symbol posterior probability of symbol code word each in each transmission time symbol code book.
It is S107, general according to the absolute value posteriority of each absolute value in Parameter Estimation Method, first of transmission time absolute value code book The symbol posterior probability of each symbol, determines the letter transmitted in first of transmission time in rate and first of transmission time symbol code book Breath.
The embodiment of the present invention provides a kind of variable length decoding method, passes through the ratio in the total B and bit stream of transmission character Special sum R, the minimum number bits N of absolute value code word in absolute value code bookminWith maximum number bits Nmax, symbolic code in symbol code book The minimum number bits x and maximum number bits t of word, determine boundary moment ldsAnd lsc, may thereby determine that the character received belongs to Which in stage；And according to the V for the first set that absolute value code book, each transmission time transmitstart, first set Vend, first Probability and bit error probability are tested, determines the absolute value posteriority of absolute value code word each in each transmission time absolute value code book Probability；According to the V' for the second set that symbol code book, each transmission time transmitstart, second set V'end, prior probability and Bit error probability determines the symbol posterior probability of symbol code word each in each transmission time symbol code book；According to parameter The absolute value posterior probability and first of transmission time symbol of each absolute value in the estimation technique, first of transmission time absolute value code book The symbol posterior probability of each symbol, determines the information transmitted in first of transmission time in code book；Since reception can be told To bit stream in each possible initial state of character corresponding bit stream therefore can more accurately know each transmission The information of moment transmission solves and when configured transmission while being related to absolute value in the prior art and when symbol is separately encoded, working as biography When defeated channel has noise jamming, since length variable decoder can not correctly not identify that each transmission character corresponds to code word in the bitstream Position, along with absolute value and symbol correspond to different code books, therefore the problem of accurately can not correctly restore source signal.
Embodiment two
The embodiment of the present invention provides a kind of variable length decoding device 10, includes as shown in Figure 4：
Acquisition module 101, the total B for obtaining the character transmitted in bit stream and total bit number R；Wherein, each word Symbol includes absolute value and symbol, and each absolute value and each symbol are individually transmitted and encoded with different code books, often A absolute value corresponding absolute value code word in absolute value code book, each symbol corresponding symbolic code in symbol code book Word, the coding mode that absolute value code book uses is variable-length encoding, and the coding mode that symbol code book uses is variable-length encoding；Wherein, B For the integer more than 0, R is the integer more than 0.
Processing module 102, the minimum number bits N for being occupied according to absolute value code word in absolute value code bookminAnd high specific Special number Nmax, the minimum number bits x that symbol code word occupies in symbol code book and the word that maximum number bits t, acquisition module 101 obtain The total bit number R that the total B and acquisition module 101 of symbol are obtained is determined and is dissipated stage and the first of the fixed stage in lattice structure Boundary moment lds, fixed stage and merging phase the second boundary moment lsc。
Processing module 102 is additionally operable to according to the first boundary moment ldsWith the second boundary moment lsc, when determining first of transmission Carve the first set of the corresponding state of absolute value and the second set of the corresponding state of symbol；Wherein, first of transmission time The minimum value of one set is Vstart, the maximum value of first of transmission time first set is Vend, first of transmission time second set Minimum value be V'start, the maximum value of first of transmission time second set is V'end；Wherein, first set includes at least one Possible state, the state in first set refers to has passed the total bit number of absolute value, second set by the end of the current transmission moment Including at least one possible state, the state in second set refers to has passed total bit of symbol by the end of the current transmission moment It counting, the total quantity for the state for including in the corresponding first set of each transmission time in the diverging stage shows a rising trend, The total quantity for the state for including in the corresponding first set of each transmission time in the fixed stage remains unchanged, and is located at and closes And the total quantity for the state in the corresponding first set of each transmission time in the stage including gradually decreases, it is known until reaching Character sum B and total number of bits R, diverging stage, fixed stage or merging phase distinguished only for absolute value.
Acquisition module 101 is additionally operable to obtain prior probability and bit error probability.
Processing module 102 is additionally operable to the V for the first set transmitted according to absolute value code book, each transmission timestart, The V of one setend, acquisition module 101 obtain prior probability and acquisition module 101 obtain bit error probability, determine every The absolute value posterior probability of each absolute value code word in a transmission time absolute value code book.
Processing module 102 is additionally operable to the V' for the second set transmitted according to symbol code book, each transmission timestart, second The V' of setend, acquisition module 101 obtain prior probability and acquisition module 101 obtain bit error probability, determine every The symbol posterior probability of each symbol code word in a transmission time symbol code book.
Processing module 102 is additionally operable to according to each absolute value in Parameter Estimation Method, first of transmission time absolute value code book Absolute value posterior probability and first of transmission time symbol code book in each symbol symbol posterior probability, determine first of transmission The information transmitted in moment.
Optionally, processing module 102 are specifically used for the minimum number bits occupied according to absolute value code word in absolute value code book NminWith maximum number bits Nmax, symbol code word occupies in symbol code book minimum number bits x and maximum number bits t, acquisition module The total bit number R that the total B and acquisition module 101 of 101 characters obtained are obtained, determines in lattice structure that absolute value is practical and uses Code word minimum number bits N'minWith the maximum number bits N' of the practical code word used of absolute value in lattice structuremax, intermediate become Measure R' and intermediate variable l'；Wherein,
N'min=max (R-Nmax×(B-1)-t×B,Nmin)；
N'max=min (R-Nmin×(B-1),Nmax)；
Wherein, the smallest positive integral value that R' is the R for meeting variable formula ", variable formula are：
R " fromStart, constantly add 1, as R and " stops adding 1 when meeting the variable formula；
Processing module 102 is specifically used for according to determining minimum number bits N'min, maximum number bits N'max, intermediate variable R' and intermediate variable l' determines the second boundary moment l that stage and merging phase are fixed in lattice structurescAnd in first set Including state sum maximum value qmax。
Processing module 102 is specifically used for according to qmax, determine the first side that stage and fixed stage are dissipated in lattice structure Boundary moment ldsAnd the maximum value of the sum for the state in second set including is equal to qmax+t。
Optionally, processing module 102 are specifically used for as determining R≤NminWhen × B+t, the second boundary moment lscEqual to B, most Big value qmaxEqual to R-N'min×B+1；
Processing module 102 is specifically used for as determining R≤Nmax×(B-l')+NminWhen × l'+t × (B-l'+1), the second side Boundary moment lscIt is equal toMaximum value qmaxEqual to R-N'min×B+1；
Processing module 102, specifically for when determining R < R', the second boundary moment lscIt is equal toMaximum value qmaxEqual to (N'max-N'min+t)×(B-lsc)+t+1；
Processing module 102 is specifically used for as determining R < NmaxWhen × B+t × (B-1), the second boundary moment lscIt is equal toMaximum value qmaxEqual to (N'max+t)×B-R+1；
Processing module 102 is specifically used for as determining R >=NmaxWhen × B+t × (B-1), the second boundary moment lscEqual to B, most Big value qmaxEqual to (N'max+t)×B-R+1；
Processing module 102 is specifically used for according to maximum value qmax, determine the first boundary moment ldsIt is equal toThe maximum value of the sum for the state for including in second set is equal to qmax+t。
Optionally, processing module 102 are specifically used for being less than or equal to the first boundary moment l as determining transmission time ldsWhen, Determine the V of first setstartEqual to N'min× l, the V of first setendEqual to N'max× l+t × (l-1), second set V'startEqual to max (Vstart,R-N'max× (B-l)-t × (B-l)), the V' of second setendEqual to min (Vend+t,R-N'min ×(B-l))；
Processing module 102 is specifically used for being more than the first boundary moment l as determining transmission time ldsAnd transmission time l is less than Or it is equal to the second boundary moment lscWhen, determine the V of first setstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the V of first setendEqual to Vstart+qmax- 1, the V' of second setstartEqual to max (Vstart,R-N'max×(B- L)-t × (B-l)), the V' of second setendEqual to min (Vend+t,R-N'min×(B-l))；
Processing module 102 is specifically used for being more than the second boundary moment l as determining transmission time lscWhen, determine first set VstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the V of first setendEqual to R-N'min×(B- L), the V' of second setstartEqual to min (Vstart+t,R-t×(B-l)-N'max× (B-l)), the V' of second setendIt is equal to R-N'min×(B-l)。
The embodiment of the present invention provides a kind of variable length decoding device, passes through the ratio in the total B and bit stream of transmission character Special sum R, the minimum number bits N of absolute value code word in absolute value code bookminWith maximum number bits Nmax, symbolic code in symbol code book The minimum number bits x and maximum number bits t of word, determine boundary moment ldsAnd lsc, may thereby determine that the character received belongs to Which in stage；And according to the V for the first set that absolute value code book, each transmission time transmitstart, first set Vend, first Probability and bit error probability are tested, determines the absolute value posteriority of absolute value code word each in each transmission time absolute value code book Probability；According to the V' for the second set that symbol code book, each transmission time transmitstart, second set V'end, prior probability and Bit error probability determines the symbol posterior probability of symbol code word each in each transmission time symbol code book；According to parameter The absolute value posterior probability and first of transmission time symbol of each absolute value in the estimation technique, first of transmission time absolute value code book The symbol posterior probability of each symbol, determines the information transmitted in first of transmission time in code book；Since reception can be told To bit stream in each possible initial state of character corresponding bit stream therefore can more accurately know each transmission The information of moment transmission solves and when configured transmission while being related to absolute value in the prior art and when symbol is separately encoded, working as biography When defeated channel has noise jamming, since length variable decoder can not correctly not identify that each transmission character corresponds to code word in the bitstream Position, along with absolute value and symbol correspond to different code books, therefore the problem of accurately can not correctly restore source signal.
Embodiment three
The embodiment of the present invention provides a kind of length variable decoder, includes any one variable length decoding dress provided such as embodiment two Set 10.Specific variable length decoding device 10 may refer to the associated description in above-mentioned apparatus embodiment two, and details are not described herein again.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any Those familiar with the art in the technical scope disclosed by the present invention, can easily think of the change or the replacement, and should all contain Lid is within protection scope of the present invention.Therefore, protection scope of the present invention should be based on the protection scope of the described claims.

Claims (9)

1. a kind of variable length decoding method, which is characterized in that including：
Obtain the total B and total bit number R of the character transmitted in bit stream；Wherein, each character includes absolute value and symbol Number, each absolute value and each symbol are individually transmitted and are encoded with different code books, and each absolute value is in absolute value A corresponding absolute value code word in code book, each symbol a corresponding symbol code word, absolute value code book in symbol code book The coding mode used is variable-length encoding, and the coding mode that the symbol code book uses is variable-length encoding；Wherein, B is more than 0 Integer, R are the integer more than 0；
The minimum number bits N occupied according to absolute value code word in the absolute value code bookminWith maximum number bits Nmax, the symbol Minimum number bits x and maximum number bits t, the total B of the character and total bit number R that symbol code word occupies in code book, Determine the first boundary moment l that stage and fixed stage are dissipated in lattice structureds, fixed stage and merging phase the second boundary Moment lsc；
According to the first boundary moment ldsWith the second boundary moment lsc, determine the corresponding state of first of transmission time absolute value First set and the corresponding state of symbol second set；Wherein, first set described in first of transmission time is most Small value is Vstart, the maximum value of first set described in first of transmission time is Vend, described in first of transmission time The minimum value of two set is V'start, the maximum value of second set described in first of transmission time is V'end；Wherein, described One set includes at least one possible state, and the state in the first set refers to have been passed absolutely by the end of the current transmission moment The total bit number of value, the second set include at least one possible state, the state in the second set refer to by the end of The current transmission moment has passed the total bit number of symbol, the corresponding first set of each transmission time being located in the diverging stage The total quantity for the state for including inside shows a rising trend, the corresponding first set of each transmission time being located in the fixed stage The total quantity for the state for including inside remains unchanged, and is located in the corresponding first set of each transmission time in the merging phase Including the total quantity of state gradually decrease, until reaching known character sum B and total number of bits R, the diverging stage, institute Fixed stage or merging phase is stated to distinguish only for absolute value；
Obtain prior probability and bit error probability；
According to the absolute value code book, the V of the first set of each transmission time transmissionstart, the first set Vend, the prior probability and the bit error probability, determine every in the absolute value code book described in each transmission time The absolute value posterior probability of a absolute value code word；
According to the symbol code book, the V' of the second set of each transmission time transmissionstart, the second set V'end, the prior probability and the bit error probability, determine each in the symbol code book described in each transmission time The symbol posterior probability of symbol code word；
Absolute value posteriority according to each absolute value in absolute value code book described in Parameter Estimation Method, first of transmission time is general The symbol posterior probability of each symbol in symbol code book described in rate and first of transmission time, when determining first of transmission The information transmitted in quarter.
2. variable length decoding method according to claim 1, which is characterized in that described according to absolute in the absolute value code book It is worth the minimum number bits N that code word occupiesminWith maximum number bits Nmax, symbol code word occupies in the symbol code book minimum bit The total B and the total bit number R of number x and maximum number bits t, the character, determine and dissipate stage and fixation in lattice structure The first boundary moment l in stageds, fixed stage and merging phase the second boundary moment lsc, including：
The minimum number bits N occupied according to absolute value code word in absolute value code bookminWith maximum number bits Nmax, accord in symbol code book Number character occupy minimum number bits x and maximum number bits t, the total B of the character and total bit number R, determine described in The minimum number bits N' of the practical code word used of absolute value in lattice structureminWith absolute value is practical in the lattice structure uses Code word maximum number bits N'max, intermediate variable R' and intermediate variable l'；Wherein,
N'min=max (R-Nmax×(B-1)-t×B,Nmin)；
N'max=min (R-Nmin×(B-1),Nmax)；
Wherein, the smallest positive integral value that R' is the R " for meeting variable formula, the variable formula are：
The R " fromStart, constantly add 1, stops adding when the R " meets the variable formula 1；
According to the determining minimum number bits N'min, the maximum number bits N'max, the intermediate variable R' and the centre Variable l' determines the second boundary moment l that stage and merging phase are fixed in lattice structurescAnd include in the first set State sum maximum value qmax；
According to the qmax, determine the first boundary moment l that stage and fixed stage are dissipated in lattice structuredsAnd described second The maximum value of the sum for the state for including in set is equal to qmax+t。
3. variable length decoding method according to claim 2, which is characterized in that described according to the determining minimum number bits N'min, the maximum number bits N'max, the intermediate variable R' and the intermediate variable l', determine the fixed stage and merge The second boundary moment l in stagescAnd the maximum value q of the sum for the state in the first set includingmax, including：
When determining R≤NminWhen × B+t, the second boundary moment lscEqual to B, maximum value qmaxEqual to R-N'min×B+1；
When determining R≤Nmax×(B-l')+NminWhen × l'+t × (B-l'+1), the second boundary moment lscIt is equal toMaximum value qmaxEqual to R-N'min×B+1；
When determining R < R', the second boundary moment lscIt is equal toMaximum value qmaxEqual to (N'max- N'min+t)×(B-lsc)+t+1；
When determining R < NmaxWhen × B+t × (B-1), the second boundary moment lscIt is equal toMaximum value qmax Equal to (N'max+t)×B-R+1；
When determining R >=NmaxWhen × B+t × (B-1), the second boundary moment lscEqual to B, maximum value qmaxEqual to (N'max+t) ×B-R+1；
According to the qmax, determine the first boundary moment l that stage and fixed stage are dissipated in lattice structuredsAnd described second The maximum value of the sum for the state for including in set is equal to qmax+ t, including：
According to the maximum value qmax, determine the first boundary moment ldsIt is equal toIn the second set Including state sum maximum value be equal to qmax+t。
4. variable length decoding method according to claim 2, which is characterized in that according to the first boundary moment ldsWith second Boundary moment lsc, determine the corresponding state of first of transmission time absolute value first set and the corresponding state of symbol Two set, including：
When determine transmission time l be less than or equal to the first boundary moment ldsWhen, determine the V of the first setstartEqual to N'min × l, the V of the first setendEqual to N'max× l+t × (l-1), the V' of the second setstartEqual to max (Vstart,R- N'max× (B-l)-t × (B-l)), the V' of the second setendEqual to min (Vend+t,R-N'min×(B-l))；
When determine transmission time l be more than the first boundary moment ldsAnd transmission time l is less than or equal to the second boundary moment lscWhen, really The V of the fixed first setstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the first set VendEqual to Vstart+qmax- 1, the V' of the second setstartEqual to max (Vstart,R-N'max× (B-l)-t × (B-l)), institute State the V' of second setendEqual to min (Vend+t,R-N'min×(B-l))；
When determine transmission time l be more than the second boundary moment lscWhen, determine the V of the first setstartEqual to max (N'min× l,R-t×(B-l+1)-N'max× (B-l)), the V of the first setendEqual to R-N'min× (B-l), the second set V'startEqual to min (Vstart+t,R-t×(B-l)-N'max× (B-l)), the V' of the second setendEqual to R-N'min× (B-l)。
5. a kind of variable length decoding device, which is characterized in that including：
Acquisition module, the total B for obtaining the character transmitted in bit stream and total bit number R；Wherein, each character packet Absolute value and symbol are included, each absolute value and each symbol are individually transmitted and encoded with different code books, each exhausted To being worth a corresponding absolute value code word in absolute value code book, each symbol a corresponding symbol code word, institute in symbol code book The coding mode that absolute value code book uses is stated as variable-length encoding, the coding mode that the symbol code book uses is variable-length encoding；Its In, B is the integer more than 0, and R is the integer more than 0；
Processing module, the minimum number bits N for being occupied according to absolute value code word in the absolute value code bookminAnd maximal bit Number Nmax, symbol code word occupies in the symbol code book minimum number bits x and maximum number bits t, the acquisition module obtain The total bit number R that the total B of the character and the acquisition module obtain, determines and dissipates stage and fixation in lattice structure The first boundary moment l in stageds, fixed stage and merging phase the second boundary moment lsc；
The processing module is additionally operable to according to the first boundary moment ldsWith the second boundary moment lsc, when determining first of transmission Carve the first set of the corresponding state of absolute value and the second set of the corresponding state of symbol；Wherein, when first of transmission The minimum value for carving the first set is Vstart, the maximum value of first set described in first of transmission time is Vend, described The minimum value of second set described in first of transmission time is V'start, the maximum of second set described in first of transmission time Value is V'end；Wherein, the first set includes at least one possible state, the state in the first set refer to by the end of The current transmission moment has passed the total bit number of absolute value, and the second set includes at least one possible state, and described second State in set refers to has passed the total bit number of symbol by the end of the current transmission moment, each biography being located in the diverging stage The total quantity for the state for including in defeated moment corresponding first set shows a rising trend, each biography being located in the fixed stage The total quantity for the state for including in defeated moment corresponding first set remains unchanged, each transmission being located in the merging phase The total quantity for the state for including in moment corresponding first set gradually decreases, until reaching known character sum B and bit Total R, the diverging stage, the fixed stage or merging phase are distinguished only for absolute value；
The acquisition module is additionally operable to obtain prior probability and bit error probability；
The processing module is additionally operable to the first set according to the absolute value code book, each transmission time transmission Vstart, the first set Vend, the institute that obtains of the prior probability that obtains of the acquisition module and the acquisition module Bit error probability is stated, is determined in the absolute value code book described in each transmission time after the absolute value of each absolute value code word Test probability；
The processing module is additionally operable to the second set transmitted according to the symbol code book, each transmission time V'start, the second set V'end, the institute that obtains of the prior probability that obtains of the acquisition module and the acquisition module Bit error probability is stated, determines that the symbol posteriority of each symbol code word in the symbol code book described in each transmission time is general Rate；
The processing module is additionally operable to according to each exhausted in absolute value code book described in Parameter Estimation Method, first of transmission time The symbol posterior probability of each symbol in symbol code book described in absolute value posterior probability and first of transmission time to value, Determine the information transmitted in first of transmission time.
6. variable length decoding device according to claim 5, which is characterized in that the processing module is specifically used for according to absolutely The minimum number bits N that absolute value code word in value code book is occupiedminWith maximum number bits Nmax, symbol code word occupies in symbol code book Minimum number bits x and maximum number bits t, the acquisition module obtain the character total B and the acquisition module obtain The total bit number R taken determines the minimum number bits N' of the practical code word used of absolute value in the lattice structureminAnd institute State the maximum number bits N' of the practical code word used of absolute value in lattice structuremax, intermediate variable R' and intermediate variable l'；Wherein,
N'min=max (R-Nmax×(B-1)-t×B,Nmin)；
N'max=min (R-Nmin×(B-1),Nmax)；
Wherein, the smallest positive integral value that R' is the R " for meeting variable formula, the variable formula are：
The R " fromStart, constantly add 1, stops adding when the R " meets the variable formula 1；
The processing module is specifically used for according to the determining minimum number bits N'min, the maximum number bits N'max, it is described The intermediate variable R' and intermediate variable l' determines the second boundary moment l that stage and merging phase are fixed in lattice structurescWith And the maximum value q of the sum for the state in the first set includingmax；
The processing module is specifically used for according to the qmax, determine the first side that stage and fixed stage are dissipated in lattice structure Boundary moment ldsAnd the maximum value of the sum for the state in the second set including is equal to qmax+t。
7. variable length decoding device according to claim 6, which is characterized in that the processing module is specifically used for as determining R ≤NminWhen × B+t, the second boundary moment lscEqual to B, maximum value qmaxEqual to R-N'min×B+1；
The processing module is specifically used for as determining R≤Nmax×(B-l')+NminWhen × l'+t × (B-l'+1), described second Boundary moment lscIt is equal toMaximum value qmaxEqual to R-N'min×B+1；
The processing module, specifically for when determining R < R', the second boundary moment lscIt is equal toMaximum value qmaxEqual to (N'max-N'min+t)×(B-lsc)+t+1；
The processing module is specifically used for as determining R < NmaxWhen × B+t × (B-1), the second boundary moment lscIt is equal toMaximum value qmaxEqual to (N'max+t)×B-R+1；
The processing module is specifically used for as determining R >=NmaxWhen × B+t × (B-1), the second boundary moment lscEqual to B, Maximum value qmaxEqual to (N'max+t)×B-R+1；
The processing module is specifically used for according to the maximum value qmax, determine the first boundary moment ldsIt is equal toThe maximum value of the sum for the state for including in the second set is equal to qmax+t。
8. variable length decoding device according to claim 6, which is characterized in that the processing module is specifically used for when determination Transmission time l is less than or equal to the first boundary moment ldsWhen, determine the V of the first setstartEqual to N'min× l, described The V of one setendEqual to N'max× l+t × (l-1), the V' of the second setstartEqual to max (Vstart,R-N'max×(B- L)-t × (B-l)), the V' of the second setendEqual to min (Vend+t,R-N'min×(B-l))；
The processing module is specifically used for being more than the first boundary moment l as determining transmission time ldsAnd transmission time l is less than or waits In the second boundary moment lscWhen, determine the V of the first setstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the V of the first setendEqual to Vstart+qmax- 1, the V' of the second setstartEqual to max (Vstart,R- N'max× (B-l)-t × (B-l)), the V' of the second setendEqual to min (Vend+t,R-N'min×(B-l))；
The processing module is specifically used for being more than the second boundary moment l as determining transmission time lscWhen, determine the first set VstartEqual to max (N'min×l,R-t×(B-l+1)-N'max× (B-l)), the V of the first setendEqual to R-N'min× (B-l), the V' of the second setstartEqual to min (Vstart+t,R-t×(B-l)-N'max× (B-l)), the second set V'endEqual to R-N'min×(B-l)。
9. a kind of length variable decoder, which is characterized in that including such as claim 5-8 any one of them variable length decoding device.
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