CN101247202A - Method for generating ldpc code for a LDPC based TDS-OFDM system - Google Patents

Abstract

In a system for generating TDS-OFDM, a method for generating LDPC codes is provided. The method comprises the steps of: constructing a base matrix; providing a plurality of sub-matrices for forming the base matrix, with each sub-matrix being a cyclic permutation matrix; and masking the base matrix using a small sparse matrix. The LDPC codes can be encoded in linear time using simple shift-registers with complexity linearly proportional to the length of the code for parallel encoding. The code and method of the present invention also optimizes the degree distributions of check nodes and bit nodes to make the error-floor lower than 10<-12>.

Description

Generate the coding new method of LDPC sign indicating number in the TDS-OFDM system

Related application is quoted

The disclosure of the Invention that the application advocates is on July 25th, 2006, and provisional application number is 60/820,319, and name is called " generating algorithm of the LDPC of different rates coding and coding in the TDS-OFDM communication system ".Require the right of 35 USC § 119 (e) in the U.S. Provisional Patent Application to incorporate above-mentioned application into for referencial use.

Technical field

The present invention relates to communication technical field, more particularly, the present invention relates to generate the coding new method of low-density checksum in the TDS-OFDM system (LDPC, Low Density Parity Check) sign indicating number.

Background technology

OFDM (OFDM, Orthogonal Frequency DivisionMultiplexing) is disclosed technology.Authorize people such as Chang, U.S. Patent number is 3,488,445 patent has been described the equipment and the method for an OFDM, it realizes the frequency division multiplexing of mass data signal on mutually orthogonal in a large number carrier wave, therefore, exist overlapping between the subcarrier, but frequency band is limited, the frequency spectrum that produces do not exist interchannel interference (ICI, Interchannel Interference) and intersymbol interference (ISI, IntersymbolInterference).The narrow band filter amplitude-frequency characteristic of each channel and phase-frequency characteristic are by they symmetry defineds separately.For each signal provides the protective capability of identical opposing interchannel noise, the signal in each channel is by incoherent media transmission seemingly, and removes intersymbol interference by reducing data transfer rate.Along with the increase of channel number, total data transfer rate is near maximum theoretical.

The OFDM transceiver is disclosed technology.Authorize people such as Fattouche, U.S. Patent number is the method that 5,282,222 patent has been described a kind of permission mutual exchange messages of a plurality of radio receiving-transmitting units (data, voice or video).In first transceiver, first frame of information is multiplexed on the broadband, sends second transceiver to.Second transceiver receives and process information.Information adopts the differential coding of phase shift keying.In addition, after the time interval of selecting in advance, first transceiver can transmit information once more.During the time interval of selecting in advance, second transceiver can be used time division duplex and other transceiver exchange message.The signal processing of second transceiver comprises to be estimated to send the phase difference of signal and carries out pre-distortion to sending signal.Transceiver comprises an encoder that is used for information coding, be used for information multiplexing to the broadband voice channel broadband frequency division multiplexing device and be used for the local oscillator of multiplexed information up conversion.Equipment comprises a processor, and it carries out Fourier transform to multiplexed information, and information conversion is transmitted to time-domain.

(PN is disclosed technology as protection interval (GI, Guard Interval) Pseudo-Noise) to adopt pseudo noise in OFDM.Authorize people such as Yang Lin, U.S. Patent number is that 7,072,289 patent has been described under the situation that has time delay in signal channel, a kind ofly estimates that transmission signal frame begins and/or the method for stop timing.Each signal frame all has a pseudorandom (PN) m sequence, and wherein the PN sequence satisfies orthogonality and irrelevant (the closures relation) that selects.Signal that receives and PN sequence are carried out convolution, and deduct the PN sequence from received signal, thereby determine the beginning and/or the end of PN sequence in the received signal.The PN sequence is used for regularly recovering, carrier wave recovers, channel transfer characteristic is estimated, received signal frame synchronization, and the protection of replacement OFDM at interval.

Low-density checksum (LDPC, Low Density Parity Check) coded system is disclosed technology.Authorize people such as Shen, U.S. Patent number is the algebraically structure that 20060156206 patent has been described the LDPC sign indicating number, parity matrix correspondingly has cyclic shift feature (CSI, Cyclic Shifted Identity) submatrix.Cyclic shift done in the feature submatrix, thereby make the parity matrix of the CSI submatrix formation LDPC sign indicating number of generation.The parity matrix of LDPC sign indicating number can rule of correspondence LDPC sign indicating number, perhaps the parity matrix of LDPC sign indicating number is made further and is revised, and it is become corresponding to irregular LDPC codes.The parity matrix of LDPC sign indicating number can be divided into 2 submatrixs, and one of them converts grouping dual diagonal matrix (Block Dual diagonal Matrix) to; Another can be revised with several different methods, comprises density evolution method, with irregular LDPC codes bit and the verification degree that guarantees to require.

Conspicuous, the LDPC coding is better than Turbo code.In addition, the LDPC sign indicating number can better be applicable to time-domain synchronization OFDM (TDS-OFDM, Time Domain Synchronous-Orthogonal Frequency DivisionMultiplexing) communication system by further modification.Therefore, need a kind of improved algorithm and device to remove to generate the LDPC sign indicating number of this TDS-OFDM of being applicable to system.

Summary of the invention

In the LDPC of TDS-OFDM system sign indicating number, provide new standard circulation parity check (H) matrix.

In the LDPC of TDS-OFDM system sign indicating number, obtain a new standard circulation by new standard circulation parity check (H) matrix and generate (G) matrix.

In the LDPC of TDS-OFDM system sign indicating number, provide a new LDPC sign indicating number structure.

In the LDPC of TDS-OFDM system sign indicating number, the new LDPC sign indicating number structure that provides is based on minimum weight (Minimum-weight) the code word structure of Read-Solomon (Reed-Solomon) sign indicating number.

In the LDPC of TDS-OFDM system sign indicating number, new LDPC sign indicating number structure uses accurate cycle characteristics to generate coding.

In the LDPC of TDS-OFDM system sign indicating number, new LDPC sign indicating number structure uses accurate cycle characteristics to generate coding, comprises and uses simple shift register.

In the LDPC of TDS-OFDM system sign indicating number, for parallel encoding, the encoder complexity and the code length of new LDPC sign indicating number structure are linear, and for serial code, linear with the check bit number.

In the LDPC of TDS-OFDM system sign indicating number, new LDPC building method distributes by the degree of optimizing check-node and bit node, makes the error code base plate be reduced to 10 ^-12Below.

Description of drawings

Reference number in the accompanying drawing refers to identical or intimate elementary cell, and accompanying drawing and following detailed have constituted an integral body together, become the key element of specification, and is used for further illustrating various specific embodiments and explains various principles of the present invention and advantage.

Fig. 1 is Tylenol (Tanner) the figure schematic diagram of LDPC decoder in the embodiment of the invention;

Fig. 2 is parity matrix figure of the present invention;

Fig. 3 is the flow chart of first example of the present invention;

Fig. 4 A-1 is first example schematic of the parity matrix of experiment;

Fig. 4 A-2 is first example schematic of the parity matrix of experiment;

Fig. 4 B-1 is second example schematic of the parity matrix of experiment;

Fig. 4 B-2 is second example schematic of the parity matrix of experiment;

Fig. 4 C-1 is the 3rd example schematic of the parity matrix of experiment;

Fig. 4 C-2 is the 3rd example schematic of the parity matrix of experiment.

What the professional person needed is that the elementary cell among the figure is showed simply, and whether describe in proportion is not necessary.For example, understand specific embodiments of the invention in order to help better, the size of some elementary cell may be by exaggerative with respect to other unit among the figure.

Embodiment

Before describing the embodiment of the invention in detail, should be noted that present embodiment is present among the combination of method step and device feature, it relates to the coding method of error correcting code, and performance has significant improvement, for example reduces error code base plate to 10 ^-12Below, the complexity of minimizing encoding and decoding realization or hardware.Correspondingly, use conventional symbol to describe these equipment and method step in the legend, only describe the crucial details relevant in detail with the specific embodiment of the invention, help everybody to understand this programme clearly, fully, in order to avoid these details are misunderstood, those of ordinary skill in the art is understood easily, and income therefrom.

In this manual, relevant term for example first and second, top and bottom, and similar term, may use separately, to distinguish different entities or processing, do not represent must needs hint these entities or processing between relation or in proper order.Term " comprises ", " by ... .. forms ", or any other associated distortion mean and comprise non-exclusive result.So, the processing of being made up of a series of elementary cells, method, article or device not only comprise those elementary cells that has indicated, the elementary cell that also may comprise other is not though these unit clearly are listed in or belong to above-mentioned processing, method, article or device." comprised " elementary cell of being quoted from, do not had under the situation of more restrictions, be not precluded within the other identical elementary cell of existence in processing, method, literal or the device that constitutes by elementary cell.

Specific embodiments of the invention as described herein are made of one or more common processors and unique stored program instruction, program command is controlled one or more processors, cooperate certain non-processor circuit, go to realize some, the function of most of or whole described error correcting code coding method, performance has significant improvement, for example reduces error code base plate to 10 ^{- 12}Below, the complexity of minimizing encoding and decoding realization or hardware.Non-processor circuit may include but not limited to wireless receiver, transmitting set, signal driver, clock circuit, power circuit and user input device.Same, these functions can be interpreted as finishing the method step of above-mentioned code construction.Select as an alternative, some or all functions can realize with the state machine that does not have stored program instructions, perhaps use one or more application-specific integrated circuit (ASIC) (ASIC, Application Specific Integrated Circuit), certain combination of a function or some functions realizes as customized logic in these ASIC.Certainly, these two kinds of methods also can be used in combination.Therefore, the ways and means of realizing these functions has been described here.Further, the expectation those skilled in the art through great efforts with many design alternatives after, for example effectively development time, current technology and the consideration of economic aspect, under the notion and guidance of principle that is here disclosed, can obtain described software instruction, program and integrated circuit (IC, Integrated Circuit) by minimum experiment easily.

The LDPC sign indicating number is the sign indicating number that a class is approached shannon limit.Because the performance that it is outstanding, the LDPC sign indicating number is widely used in plurality of communication systems, particularly to the system of performance requirement harshness.The mentality of designing of LDPC sign indicating number can briefly be divided into 2 big classes, is called LDPC sign indicating number and structured LDPC code at random.The design of LDPC sign indicating number normally relies on the mainframe computer search and gets under the multiple constraints of deriving from graph structure at random.The design of structured LDPC code is based on the method for algebraical sum combination.Designing outstanding structured LDPC code can reach aspect bit error rate, the bag error rate, error code base plate and the decoding convergence rate and the suitable performance of LDPC sign indicating number at random.In fact, structured LDPC code generally has lower error code base plate, and this digital communication system for the suitable low error rate of needs is very important.Structuring sign indicating number with big minimum range is than the easier structure of random code that generates with calculating.In addition, the structuring sign indicating number, quasi-cyclic LDPC code for example more has the coding advantage than the LDPC coding of other type.The coding of these structuring sign indicating numbers can use simple shift register to realize having linear complexity, corresponding with it, the encoder complexity of the sign indicating number of LDPC at random that computer generates is a quadratic equation.Because the accurate loop structure of these structured LDPC codes, they also have advantage aspect the decoder realization.These advantages will be done more detailed elaboration below.

Can see that not having or lacking good structure is the major defect and the inferior position of LDPC sign indicating number at random.A reason of this shortcoming is because the realization complexity of encoder is quite high, and is more expensive more than structured LDPC code when causing realizing.In contrast, at least in this respect, structured LDPC code is compared with LDPC sign indicating number at random huge advantage.

The LDPC sign indicating number also can be classified as regular LDPC sign indicating number and abnormal LDPC code according to their matrix structure.For regular LDPC sign indicating number coding, their parity matrix (H) has constant capable weight and constant column weight amount.For abnormal LDPC code, their parity matrix (H) does not have constant capable weight and column weight amount.For the sign indicating number of short circulation, after 2 iteration, it is relevant that iterative decoding will become, thereby decoding is not restrained or restrain very slow.Therefore, in sign indicating number structure, length of the cycle is 4 to be undesirable, should avoid as far as possible or delete.It should be noted that the distribution of " 1 " will produce very big influence to corresponding LDPC sign indicating number in parity matrix.What the present invention used is abnormal LDPC code.

Generally speaking, under identical constraints, the more approaching theoretical shannon limit of the bit error rate of abnormal LDPC code (BER, Bit Error Rate) curve ratio rule LDPC sign indicating number.In other words, on the ability of the approximation theory limit, the performance of abnormal LDPC code is better than regular LDPC sign indicating number.On the other hand, the error code base plate of abnormal LDPC code is usually above regular LDPC sign indicating number.Because in digital television broadcasting system, require bit error rate (BER) to be lower than 10 ^-12, therefore, desirable LDPC sign indicating number should possess abnormal LDPC code near the characteristic of theoretical shannon limit and the regular LDPC sign indicating number characteristic than the low bit error base plate.

Nearest studies show that, possesses near theoretical shannon limit simultaneously and is mutual contradiction than the target of low bit error base plate.In other words, the BER curve is more near shannon limit, and the error code base plate is just high more, and vice versa.Therefore, by paying the cost of high bit error base plate, can obtain excellent low signal-to-noise ratio (SNR, Signal-to-Noise Ratio) performance usually.In a communication system, ground/hand-held digital multimedia/television broadcasting (DMB-TH) system for example, the present invention attempts to use different methods for designing to solve this two conflicting problems when the LDPC sign indicating number designs, when in given bit error rate scope, not having error code, make the bit error rate curve a little away from shannon limit.

LDPC sign indicating number structure in the DMB-TH system is based on the minimum weight code word of Reed Solomon code, and the degree that passes through the Tanner figure of optimization bit node and check-node simultaneously distributes, and makes the error code base plate be reduced to 10 ^-12Below.Tanner figure sees Fig. 1.

With reference to Fig. 1, represented the Tanner Figure 10 in the LDPC sign indicating number decoder among the figure, the decode procedure of low-density checksum (LDPC) sign indicating number can be by Tanner figure expression shown in Figure 1.c _jBe defined as check-node, b _iBe defined as bit node.Note c _jTo b _iCorrelation be expressed as r _Ji, b _iTo c _jBe q _IjTanner figure is a common method of describing LDPC sign indicating number decoder.

With reference to Fig. 2 and Fig. 3, the sign indicating number that the present invention generates is quasi-cyclic, and their generator matrix and parity matrix are made of a large amount of submatrixs.Each submatrix all is a circular matrix, is called as cyclic determinant.Accurate loop structure makes it can realize the coding of LDPC sign indicating number by simple shift register and logical circuit.In addition, accurate loop structure has thoroughly reduced the complexity that decoding realizes, thus the cost that has reduced operation effectively and used.

Based on the minimum weight code word of Reed Solomon code, the H of a m * n of structure _RsArray, it is the cyclic determinant of (b-1) * (b-1), wherein 1＜m≤n and b are the power (for example b=127) of prime number, H _RsBe expressed as follows:

$H_{\mathrm{rs}}=\left[\begin{array}{ccccccccccc}0& {\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="A20071013000700211.png,A20071013000700221.png"\; state="\{\{state\}\}">\; <figure-callout\; id="2"\; label="A"\; filenames="A20071013000700221.png,A20071013000700231.png"\; state="\{\{state\}\}">A</figure-callout>\; </figure-callout>}}_{\mathrm{1,2}}& .& .& .& {\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="A20071013000700211.png,A20071013000700221.png"\; state="\{\{state\}\}">A</figure-callout>}}_{1,\mathrm{<figure-callout\; id="1"\; label="m\; A"\; filenames="A20071013000700211.png,A20071013000700221.png"\; state="\{\{state\}\}">m</figure-callout>}}& A_{}{}_{1,m+1}& .& .& .& {\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="A20071013000700211.png,A20071013000700221.png"\; state="\{\{state\}\}">A</figure-callout>}}_{1,\mathrm{<figure-callout\; id="2"\; label="n\; A"\; filenames="A20071013000700221.png,A20071013000700231.png"\; state="\{\{state\}\}">\; <figure-callout\; id="1"\; label="n\; A"\; filenames="A20071013000700211.png,A20071013000700221.png"\; state="\{\{state\}\}">n</figure-callout>\; </figure-callout>}}& \\ A_{}{}_{}{}_{\mathrm{2,1}}& 0& .& .& .& {\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="A20071013000700221.png,A20071013000700231.png"\; state="\{\{state\}\}">A</figure-callout>}}_{2,\mathrm{<figure-callout\; id="2"\; label="m\; A"\; filenames="A20071013000700221.png,A20071013000700231.png"\; state="\{\{state\}\}">m</figure-callout>}}& A_{}{}_{2,m+1}& .& .& .& {\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="A20071013000700221.png,A20071013000700231.png"\; state="\{\{state\}\}">A</figure-callout>}}_{2,n}\\ .& .& & .& & .& .& & .& & .\\ .& .& & .& & .& .& & .& & .\\ .& .& & .& & .& .& & .& & .\\ A_{m,1}& A_{m,2}& .& .& .& 0& A_{m,m+1}& .& .& .& A_{m,n}\end{array}\right]$

For H _Rs, H _RsEach of a m row of array comprises one 0 cyclic determinant, H _RsEach of other n-m row comprise m (b-1) * (b-1) cyclic determinant permutation matrix.Therefore, H _RsBe m (b-1) * n (b-1) matrix in GF (2) territory, the weight of m (b-1) row is m-1, and (n-m) weight of (b-1) row is m.H _RsAll the row weight are n-1.It follows the architectural characteristic of unified class of minimum weight of reed-solomon (RS) sign indicating number and their character position vector, H _RsIn do not have total " 1 " the component number of two row (or two row) more than 1.Guaranteed H like this _RsTanner figure can not comprise length be 4 circulation.H _RsAs basic matrix.

By following steps structure basic matrix H _RsConsider (q-1,2, q-2) circulation RS sign indicating number C on GF (q) territory _bC _bIn each of (m-w) individual code word have one and have only one 0 component, 2 of a m-w sign indicating number word have identical coded identification at the most on a position.Make v _i=(v _{I, 0}, v _{I, 1}... v _{I, q-2}) be C _bIn of m-w code word, its j component v _Ij=0.For 0≤i＜q-1, make Q _i={ v _i, α v _i... α ^Q-2v _i.Can clearly draw Q _iThe i component of each of middle m-w code word equals zero.Q _iBe called C _bA standard class of m-w code word.Two standard class will be separated, so C _b(q-1) ²The m-w code word is divided into (q-1) individual standard class, Q ₀..., Q _Q-1As 0≤i, during j＜q-1, at Q _iIn, m-w code word α ^jv _iEach coded identification represent that by their position vector we obtain (q-1) on GF (2) ²-tuple z (α ^jv _i), its weight is q-2, is called α ^jv _iThe character position vector.When 0≤i＜q-1, use Q _iThe character position vector of middle m-w code word constitutes one (q-1) (q-1) as row ²Matrix B _iSo B _i=(A _{I, 0}, A _{I, 1}... A _{I, q-2}) be (q-1) * (q-1) by a row cyclic transformation matrix and the null matrix A that can be counted as cyclic determinant _{I, i}Form.B ₀, B ₁... B _Q-2Be placed on as submatrix and list, form the H of (q-1) x (q-1) _Rs=[A _{I, j}] (q-1) x (q-1) cyclic determinant array.H _RsBe (q-1) on GF (2) ²(q-1) ²Matrix.

At a basic matrix H who forms by onesize cyclic determinant permutation matrix _RsAfter being fabricated, will use macking technique.In macking technique,, go up the little sparse matrix Z that one of structure has suitable " 1 " to distribute at GF (2) in order to shelter processing.In order to use Z masked radical matrix H _Rs, the first step obtains a matrix of sheltering earlier $M=Z\&CircleTimes;H_{\mathrm{rs}}$ 。The matrix M of sheltering is made up of a cyclic transformation array and onesize null matrix.Make up masking matrix Z and be based in the code pattern, Tanner figure for example shown in Figure 1, the degree of bit node and check-node distributes.Macking technique among the present invention has significantly been simplified the random structure of abnormal LDPC code.Macking technique has also avoided the edge at random in the sign indicating number figure structure to select, and this degree that is based on node of graph distributes and generates the demand of abnormal LDPC code.It is n * (b-1), the code check abnormal LDPC code for (n-m)/n that the empty position of the matrix M after sheltering (Null Space) has provided length.Note operator

Do not represent matrix multiplication, replace, operator

Represent selection course, i.e. H _RsIn the masked Z of some element be changed to 0.

As a real example, suppose:

$H_{\mathrm{rs}}=\left(\begin{array}{ccc}0& d& e\\ a& 0& 0\\ \mathrm{<figure-callout\; id="0"\; label="c\; b"\; filenames="A20071013000700211.png,A20071013000700241.png"\; state="\{\{state\}\}">c</figure-callout>}& b& 0\end{array}\right)$

And masking matrix

$Z=\left(\begin{array}{ccc}0& 0& 0\\ 1& 0& 0\\ 1& 1& 0\end{array}\right)$

End product is

$Z\&CircleTimes;H_{\mathrm{rs}}=\left(\begin{array}{ccc}0& 0& 0\\ a& 0& 0\\ \mathrm{<figure-callout\; id="0"\; label="c\; b"\; filenames="A20071013000700211.png,A20071013000700241.png"\; state="\{\{state\}\}">c</figure-callout>}& b& 0\end{array}\right)$

In other words, except a, b and c, other positions of the matrix after sheltering all are 0.

After masking procedure, obtain parity check matrix H, see Fig. 2, it is the capable m row of n, n, m are positive integers, simultaneously m＞n.In addition, parity check matrix H can be thought by a square formation H _SqWith a remaining matrix H _rForm.In other words, parity check matrix H=[H _SqH _r], remaining matrix H _rThan square formation H _SqHas higher degree.H on diagonal _SqIt all is null matrix.On first sub-diagonal, provide series of identical cyclic permutation submatrix.Similarly, on second sub-diagonal, provide series of identical cyclic permutation submatrix, except different on the position of " 1 " and the first sub-diagonal.On the 3rd sub-diagonal, provide series of identical cyclic permutation submatrix, except different on the position of " 1 " and the first and second sub-diagonal.For example, in Fig. 4 A-1 and Fig. 4 A-2, in cornerwise first row of first son, the position of single " 1 " is the 1st row (noticing that the row label is to n-1 from 0).Similarly, in second and cornerwise first row of the 3rd son, the position of single " 1 " is respectively 32 and 104.In other words, the masking matrix Z of special code has a series of " 1 " at three continuous sub-diagonal, is similar to the sub-diagonal of H, i.e. a _Ij, b _IjAnd c _Ij

Referring to Fig. 3, provided flow process Figure 60 of the present invention.Provide some submatrixs to be used for constructing basic matrix, each submatrix is cyclic permutation matrices (step 62).Use these submatrix structure basic matrixs (step 64).Shelter this basic matrix with predetermined sparse matrix, be used for the element in the basic matrix is selected, remain with usefulness, remove other element (step 66).Matrix after use is sheltered is as parity matrix (step 68).

Referring to Fig. 4 A-1 to Fig. 4 C-2, provided example according to three parity matrixs of the present invention's structure.In the DMB-TH system, these three examples generate the LDPC sign indicating number of different code checks, and they are respectively (7493,3048), (7493,4572) and (7493,6096) LDPC sign indicating number, and corresponding code rate is 0.4,0.6 and 0.8.The parity matrix of these three sign indicating numbers has accurate loop structure, has optimized the bit node of Tanner figure of they correspondences and the degree of check-node and has distributed.The generator matrix G of these three LDPC sign indicating numbers also is quasi-cyclic, can use shift register that generator matrix G is encoded.More than three kinds of codings good iterative decoding performance is not only arranged, and its low-down error code base plate can satisfy the requirement of digital television broadcasting.

The structure of LDPC sign indicating number is based on the minimum weight code word of Reed Solomon code in the TDS-OFDM system.At first, for a H matrix (referring to Fig. 1) is set up in decoding, sign indicating number of the present invention is a quasi-cyclic code.Quasi-cyclic code is a kind of uniform enconding, and code word is carried out n ₀The fixed cycles displacement of position, wherein n ₀Be not equal to 1, n perhaps is shifted ₀Multiple, no matter move to left or move to right, the result still is another code word.Than the LDPC sign indicating number of other type, quasi-cyclic LDPC code takes advantage at encoding context.In linear session, quasi-cyclic low-density parity check codes (QC-LDPC, Quasi-cyclic Low Density Parity Check) sign indicating number can use simple shift register coding, and complexity and code length during parallel encoding are linear.The degree that coding of the present invention and method have also been optimized check-node and bit node distributes, thereby makes the error code base plate drop to 10 ^-12Below.

In the LDPC of communication system sign indicating number, provide a method that generates the LDPC sign indicating number.This method comprises following a few step: construct a basic matrix; In order to make up this basic matrix, the submatrix of some is provided, each submatrix all is a cyclic permutation matrices; Use little sparse matrix to shelter this basic matrix.

In the LDPC of communication system sign indicating number, provide a parity matrix.This parity matrix comprises: a square formation and a remaining combinations of matrices.This square formation comprises: all elements on the leading diagonal all is zero; The first sub-diagonal is positioned at below the leading diagonal, is series of identical cyclic permutation submatrix; The second sub-diagonal is positioned at below the first sub-diagonal, is series of identical cyclic permutation submatrix, except the position of " 1 " is different with first sub cornerwise cyclic permutation submatrix; The 3rd sub-diagonal is positioned at below the second sub-diagonal, is series of identical cyclic permutation submatrix, except position and first of " 1 ", second cornerwise cyclic permutation submatrix of son are different.

Notice that the present invention has used and authorize PN sequences people such as Yang Lin, described in the 7th, 072, No. 289 patents of the U.S., merge into a single whole as a reference at this.

In conjunction with the accompanying drawings specific embodiments of the invention are had been described in detail above, but the present invention is not restricted to the foregoing description, do not breaking away under the spirit and scope situation of claim of the present invention, those of ordinary skill in the art can make various modifications or change.Therefore, this specification and block diagram be illustrative and nonrestrictive, simultaneously, all modifications is included in the scope of the present invention.The solution of benefit, advantage, problem and may produce benefit, advantage or any elementary cell of the solution that produces solution or become clearer and more definite can not explained as characteristic or principle important, essential or essence in any or all of claim.Following claim comprises any correction of the application during uncertain and all rights that are equal to of those claims of promulgation, has defined the present invention individually.

Claims (22)

1. the building method of LDPC sign indicating number in the communication system is characterized in that, comprises following several steps:

1) basic matrix of structure;

2) provide some submatrixs that generate basic matrix, each submatrix is a cyclic permutation matrices;

3) use a little sparse matrix masked radical matrix.

2. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and the basic matrix after described the sheltering is as parity matrix.

3. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and the step of described structure generator matrix is the same with parity matrix.

4. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and described communication system is based on the TDS-OFDM system that comprises the LDPC sign indicating number.

5. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and described masking procedure may further comprise the steps:

1) provide a sparse masking matrix, it has the distribution of " 1 " entity of suitable design;

2) matrix after generation is sheltered.

6. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, does not have two row or two to be listed as " 1 " component that has more than in the described basic matrix.

7. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and described LDPC sign indicating number is structurized LDPC sign indicating number.

8. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and described LDPC sign indicating number is a quasi-cyclic LDPC code.

9. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and described LDPC sign indicating number can use simple shift register to realize coding, has linear complexity.

10. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, and described parity matrix is by forming with the onesize cyclic permutation matrices array of basic matrix.

11. the building method of LDPC sign indicating number is characterized in that in the communication system as claimed in claim 1, described parity matrix comprises:

A square formation and a remaining combinations of matrices;

And square formation comprises:

All elements on the leading diagonal all is a null matrix;

The first sub-diagonal is positioned at below the leading diagonal, is series of identical cyclic permutation submatrix;

The second sub-diagonal is positioned at below the first sub-diagonal, is series of identical cyclic permutation submatrix, except the position of " 1 " is different with first sub cornerwise cyclic permutation submatrix; Simultaneously

The 3rd sub-diagonal is positioned at below the second sub-diagonal, is series of identical cyclic permutation submatrix, except the sub cornerwise cyclic permutation submatrix of position and first, second of " 1 " is different.

12. in a communication system that adopts the LDPC sign indicating number, the parity matrix of LDPC sign indicating number comprises:

A square formation and a remaining combinations of matrices;

And square formation comprises:

All elements on the leading diagonal all is a null matrix;

The first sub-diagonal is positioned at below the leading diagonal, is series of identical cyclic permutation submatrix;

The second sub-diagonal is positioned at below the first sub-diagonal, is series of identical cyclic permutation submatrix, except the position of " 1 " is different with first sub cornerwise cyclic permutation submatrix; Simultaneously

The 3rd sub-diagonal is positioned at below the second sub-diagonal, is series of identical cyclic permutation submatrix, except the sub cornerwise cyclic permutation submatrix of position and first, second of " 1 " is different.

13. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that described remaining matrix is made up of the matrix with degree higher than square formation.

14. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that, described square formation is removed outside the rank rear of last two row of first row and second row, and all the other all are zero.

15. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that described parity matrix derives from basic matrix.

16. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that a series of submatrixs have constituted basic matrix.

17. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that, the basic matrix after described the sheltering constitutes parity matrix.

18. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that described parity matrix is used for the LDPC sign indicating number of TDS-OFDM communication system.

19. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that, described parity matrix is made up of a series of and the onesize cyclic permutation matrices of basic matrix.

20. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that, described LDPC low density parity check code can use simple shift register to realize coding, has linear complexity.

21. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that described LDPC sign indicating number is a quasi-cyclic LDPC code.

22. the communication system that adopts the LDPC sign indicating number as claimed in claim 12 is characterized in that, described LDPC coding is structurized LDPC sign indicating number.

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