CN106385262A - LDPC encoder with secondary part parallel input rightward movement accumulation in CMMB - Google Patents

Abstract

The invention provides a QC-LDPC encoder based on a secondary streamline in CMMB. The encoder comprises one multiplexer for a sparse matrix and a vector, and a multiplexer for the vector and a high-density matrix. The multiplexer for the sparse matrix and the vector realizes multiplication operation between the sparse matrix and the vector. A partial parallel input rightward movement accumulation mechanism is utilized in the multiplexer for the vector and the high-density matrix, thereby realizing multiplication operation between the vector and the high-density matrix. A whole coding process is divided into two stages of streamlines. The 3/4-code-rate QC-LDPC encoder in the CMMB system according to the invention has advantages of low cost, high throughput amount, etc.

Description

In CMMB, the parallel input of second part moves to right cumulative LDPC encoder

Technical field

The present invention relates to field of channel coding, move to right cumulative particularly to a kind of parallel input of second part in CMMB system QC-LDPC encoder.

Background technology

Low-density checksum (Low-Density Parity-Check, LDPC) code be efficient channel coding technology it One, and quasi-cyclic LDPC (Quasi-Cyclic LDPC, QC-LDPC) code is a kind of special LDPC code.The life of QC-LDPC code Become matrix G and check matrix H to be all the array being made up of circular matrix, there is stages cycle, therefore be referred to as QC-LDPC Code.The first trip of circular matrix is the result of footline ring shift right 1, and remaining each row is all the knot of its lastrow ring shift right 1 Really, therefore, circular matrix to be characterized by its first trip completely.Generally, the first trip of circular matrix is referred to as its generator polynomial.

CMMB standard employs the QC-LDPC code of system form, and the left-half of its generator matrix G is a unit square Battle array, right half part is by e × c b × b rank circular matrix G_i,j(1≤i≤e,e<J≤t, t=e+c) array that constitutes, as follows Shown：

Wherein, I is b × b rank unit matrix, and 0 is b × b rank full null matrix.The continuous b row of G and b row are known respectively as block Row and block row.From formula (1), G has e block row and t block row.CMMB standard employs a kind of QC-LDPC code of code check η=3/4, For this code, t=36, e=27, c=9, b=256.

In CMMB standard, the existing solution of 3/4 code check QC-LDPC encoder is to be added based on 9 I type shift registers The serial encoder of accumulator (Type-I Shift-Register-Adder-Accumulator, SRAA-I) circuit.By 9 The serial encoder that SRAA-I circuit is constituted, completed to encode within 6912 clock cycle.The program 4608 depositors of needs, 2304 two inputs input XOR gates with door and 2304 two in addition it is also necessary to the generation of 62208 bit ROM storage circular matrixes is multinomial Formula.The program has two shortcomings：One is to need a large amount of memorizeies, leads to circuit cost high；Two is serial input information bit, compiles Code speed is slow.

Content of the invention

In CMMB system there is high cost, slow the lacking of coding rate in the existing implementation of 3/4 code check QC-LDPC encoder Point, for these technical problems, the invention provides a kind of QC-LDPC encoder based on two-level pipeline.

As shown in figure 1, the QC-LDPC encoder based on two-level pipeline is mainly made up of 2 parts in CMMB system：Sparse Matrix and vectorial multiplier and the vectorial multiplier with high-density matrix.Cataloged procedure divides 2 steps to complete：1st step, using sparse Matrix calculates vectorial s with the multiplier of vector；2nd step, calculates the vectorial p of verification using the multiplier of vector and high-density matrix.

Advantage and method with regard to the present invention can be further understood by following detailed description and accompanying drawings.

Brief description

Fig. 1 is the QC-LDPC cataloged procedure based on two-level pipeline；

Fig. 2 is the multiplier of sparse matrix and vector；

Fig. 3 is the functional block diagram that II type shift register adds accumulator SRAA-II circuit；

Fig. 4 is that a kind of the input based on part parallel being made up of c SRAA-II circuit moves to right cumulative vector and high density Matrix multiplier；

Fig. 5 summarizes hardware resource and process time needed for each coding step of encoder and whole cataloged procedure.

Specific embodiment

Below in conjunction with the accompanying drawings presently preferred embodiments of the present invention is elaborated, so that advantages and features of the invention can be more It is easy to be readily appreciated by one skilled in the art, thus protection scope of the present invention is made apparent clearly defining.

The row weight of circular matrix and row heavy phase are same, are denoted as w.If w=0, then this circular matrix is full null matrix.If W=1, then this circular matrix is replaceable, referred to as permutation matrix, it can be by positions some to unit matrix I ring shift right Obtain.The check matrix H of QC-LDPC code is by c × t b × b rank circular matrix H_j,k(1≤j≤c, 1≤k≤t, t=e+c) The following array constituting：

Under normal circumstances, the arbitrary circular matrix in check matrix H is full null matrix (w=0) or being displacement square Battle array (w=1).Make circular matrix H_j,kFirst trip h_j,k=(h_j,k,1,h_j,k,2,…,h_j,k,b) it is its generator polynomial, wherein h_j,k,m =0 or 1 (1≤m≤b).Because H is sparse, h_j,kOnly 1 ' 1 ', even without ' 1 '.

The front e block row of H are corresponding to be information vector a, and rear c block row are corresponding to be the vectorial p of verification, code word v=(a, p).With b Bit is one section, and information vector a is divided into e section, i.e. a=(a₁,a₂,…,a_e)；The vectorial p of verification is divided into c section, i.e. p= (p₁,p₂,…,p_c).The matrix that the front e block row of H and rear c block row are constituted is denoted as C and D respectively, then

H=[C D] (3)

C is to be made up of c × e b × b rank circular matrix, and D is to be made up of c × c b × b rank circular matrix.By formula (3) and Code word v=(a, p) substitutes into Hv^T=0, arrangement can obtain

p^T=Φ^TCa^T(4)

Wherein, Φ^T=D^–1, subscript^TWith^–1Represent transposition and inverse of a matrix respectively, D must full rank.It is known that Cyclic Moment Battle array inverse, product and remain circular matrix.Therefore, Φ is also the array being made up of circular matrix.But although matrix D is Sparse, but Φ is generally no longer sparse but highdensity.

Make s^T=Ca^TAnd p^T=Φ^Ts^T, then p=s Φ.Calculate the multiplication that s is related to sparse matrix and vector using C, using Φ Calculate the multiplication that p is related to vector and high-density matrix.From the above discussion, a kind of QC- based on two-level pipeline can be provided LDPC cataloged procedure, as shown in Figure 1.

Make s=(s₁,s₂,…,s_c), then s_j ^TIt is jth block row and a of Matrix C^TProduct, that is,

$s_j^T=H_{j,1}{a}_1^T+H_{j,2}{a}_2^T+...+H_{j,i}{a}_i^T+...+H_{j,e}{a}_e^T---\left(5\right)$

Wherein, 1≤i≤e, 1≤j≤c.s_jThe n-th bit s_j,n(1≤n≤b) is

$\begin{array}{c}{s}_{j,n}=h_{j,1}^{rs(n-1)}{a}_1+h_{j,2}^{rs(n-1)}{a}_2+...+h_{j,i}^{rs(n-1)}{a}_i+...+h_{j,e}^{rs(n-1)}{a}_e\\ =h_{j,1}{a}_1^{ls(n-1)}+h_{j,2}{a}_2^{ls(n-1)}+...+h_{j,i}{a}_i^{ls(n-1)}+...+h_{j,e}{a}_e^{ls(n-1)}\end{array}---\left(6\right)$

Wherein, subscript^rs(n–1)With^ls(n–1)Represent ring shift right n 1 and ring shift left n 1 respectively.Since arbitrary circulation Matrix generator polynomial h_j,iOnly a small amount of ' 1 ' even complete zero, then the inner product in formula (6) can be by posting to ring shift left The tap of storage is sued for peace and to be realized, the multiplier of sparse matrix as shown in Figure 2 and vector.Sparse matrix and vectorial multiplier By t b bit register R_1,1,R_1,2,…,R_1,tWith c multi input XOR gate X_1,1,X_1,2,…,X_1,cComposition.Depositor R_1,1, R_1,2,…,R_1,eFor loading and ring shift left message segment a₁,a₂,…,a_e, depositor R_1,e+1,R_1,e+2,…,R_1,tFor storing s Array section s₁,s₂,…,s_c.Partially connected in Fig. 2 depends on all circular matrix generator polynomials in Matrix C.If h_j,i,m=1 (1≤m≤b), then message segment a_iM bit be connected to XOR gate X_1,j.Therefore, depositor R_1,iAll take out Head is depending on the nonzero element position of all circular matrix generator polynomials in i-th piece of row of Matrix C, and multi input XOR gate X_1,jInput depend on Matrix C jth block row in all circular matrix generator polynomials nonzero element position.If in C All circular matrix generator polynomials have α ' 1 ', then sparse matrix needs use (α c) individual with the multiplier of vector Two input XOR gates calculate s simultaneously_1,n,s_2,n,…,s_c,n.S can calculate within b clock cycle and finish.Using sparse matrix with The step that the multiplier of vector calculates vectorial s is as follows：

1st step, input information section a₁,a₂,…,a_e, they are stored in respectively depositor R_1,1,R_1,2,…,R_1,eIn；

2nd step, depositor R_1,1,R_1,2,…,R_1,eRing shift left 1 time simultaneously, XOR gate X_1,1,X_1,2,…,X_1,cRespectively will XOR result moves to left into depositor R_1,e+1,R_1,e+2,…,R_1,tIn；

3rd step, repeats the 2nd step b-1 time, after the completion of, depositor R_1,e+1,R_1,e+2,…,R_1,tStorage content be respectively to Amount section s₁,s₂,…,s_c, they constitute vectorial s.

p^T=Φ^Ts^TIt is equivalent to p=s Φ.Φ is by c × c b × b rank circular matrix Φ_j,u(1≤j≤c,1≤u≤c) The array constituting.Make circular matrix Φ_j,uFirst trip g_j,uIt is its generator polynomial.From p=s Φ, u section verification vector is full Foot

p_u=s₁Φ_1,u+s₂Φ_2,u+…+s_jΦ_j,u+…+s_cΦ_c,u(7)

Make generator polynomial g_j,u=(g_j,u,1,g_j,u,2,…,g_j,u,b), then Φ_j,uCan be considered unit matrix ring shift right version This weighted sum, that is,

Φ_j,u=g_j,u,1I^r(0)+g_j,u,2I^r(1)+…+g_j,u,bI^r(b-1)(8) wherein, subscript^r()Represent ring shift right.That , the jth item on the right of formula (7) equal sign is deployable to be

$\begin{array}{c}{s}_j{\mathrm{\&Phi;}}_{j,u}=s_j(g_{j,u,1}{I}^{r\left(0\right)}+g_{j,u,2}{I}^{r\left(1\right)}+...+g_{j,u,b}{I}^{r(b-1)})\\ =g_{j,u,1}{s}_j{I}^{r\left(0\right)}+g_{j,u,2}{s}_j{I}^{r\left(1\right)}+...+g_{j,u,b}{s}_j{I}^{r(b-1)}\\ =g_{j,u,1}{s}_j^{r\left(0\right)}+g_{j,u,2}{s}_j^{r\left(1\right)}+...+g_{j,u,b}{s}_j^{r(b-1)}\end{array}---\left(9\right)$

Formula (9) is one and moves to right-the process of-multiply-add-storage, its realization adds accumulator (Type- with II type shift register IIShift-Register-Adder-Accumulator, SRAA-II) circuit.Fig. 3 is the functional block diagram of SRAA-II circuit, to Amount s sends into this circuit with b bit parallel for one section.When with SRAA-II circuit to verification section p_uWhen (1≤u≤c) is encoded, Generator polynomial look-up table prestores all generator polynomials of the u block row of matrix Φ, and accumulator is cleared initialization.When When 1st clock cycle arrives, array section s₁Move into shift register, generator polynomial look-up table export the 1st piece of row of Φ, the Generator polynomial Φ of u block row_1,uThe 1st bit g_1,u,1, and the content with shift registerCarry out scalar multiplication, productAdd with content 0 mould 2 of accumulator, andIt is stored back to accumulator.When arriving the 2nd clock cycle, shift LD Device ring shift right 1, content is changed intoGenerator polynomial look-up table exports Φ_1,uThe 2nd bit g_1,u,2, and post with displacement The content of storageCarry out scalar multiplication, productContent with accumulatorMould 2 adds, and It is stored back to accumulator.Above-mentioned move to right-- multiply-add-storing process proceeds down.At the end of b-th clock cycle, generate multinomial Formula look-up table has exported Φ_1,uLast bit g_1,u,b, now accumulator storage is part and s₁Φ_1,u, this is vector Section s₁To p_uContribution.When arriving the b+1 clock cycle, array section s₂Move into shift register, repeat above-mentioned move to right-take advantage of- Plus-storing process.When generator polynomial look-up table has exported Φ_2,uLast bit g_2,u,bWhen, accumulator storage is portion Divide and s₁Φ_1,u+s₂Φ_2,u.Repeat said process, until entirely vectorial s all moves into circuit parallel.Now, accumulator stores It is verification section p_u.

Fig. 4 is given a kind of the input based on part parallel being made up of c SRAA-II circuit and moves to right cumulative vector and height Density matrix multiplier, by shift register, generator polynomial look-up table, b position binary multiplier, b position binary adder With five kinds of functional module compositions of accumulator.Shift register is to array section s_j(1≤j≤c) ring shift right.Generator polynomial is searched Table L₁,L₂,…,L_cPrestore matrix Φ the 1,2nd respectively ..., all circular matrix generator polynomials in c block row.Generator polynomial Look-up table L₁,L₂,…,L_cThe generator polynomial bit of output carries out scalar multiplication with the content of shift register respectively, this c mark Amount multiplication passes through b position binary multiplier M respectively₁,M₂,…,M_cComplete.B position binary multiplier M₁,M₂,…,M_cProduct divide Not and accumulator R₁,R₂,…,R_cContent be added, this c nodulo-2 addition is respectively by b position binary adder A₁,A₂,…,A_c Complete.B position binary adder A₁,A₂,…,A_cAnd be stored in accumulator R respectively₁,R₂,…,R_c.

Generator polynomial look-up table L₁,L₂,…,L_cCircular matrix generator polynomial in storage matrix Φ.Generator polynomial Look-up table L₁～L_cAll generator polynomials in 1～c block row of storage Φ, for any block row, store the 1st successively respectively, 2 ..., the corresponding generator polynomial of c block row.Generator polynomial look-up table L₁～L_cThe bit of Serial output generator polynomial.

The step calculating the vectorial p of verification using the multiplier of vector and high-density matrix is as follows：

1st step, resets accumulator R₁,R₂,…,R_c；

2nd step, shift register input vector section s_j(1≤j≤c)；

3rd step, generator polynomial look-up table L₁,L₂,…,L_cRespectively the 1,2nd in output matrix Φ jth block row ..., c block arranges Generator polynomial bit, these generator polynomial bits respectively pass through b position binary multiplier M₁,M₂,…,M_cPost with displacement The content of storage carries out scalar multiplication, b position binary multiplier M₁,M₂,…,M_cProduct respectively pass through b position binary adder A₁,A₂,…,A_cWith accumulator R₁,R₂,…,R_cContent be added, b position binary adder A₁,A₂,…,A_cAnd be stored in respectively Accumulator R₁,R₂,…,R_c；

4th step, shift register ring shift right one, repeats the 3rd step b-1 time；

5th step, is incremented by, with 1 for step-length, the value changing j, repeats the 2nd～4 step c-1 time, until entirely vectorial s has inputted Finish, now, accumulator R₁,R₂,…,R_cStorage is verification section p respectively₁,p₂,…,p_c, they constitute the vectorial p=of verification (p₁,p₂,…,p_c).

The invention provides a kind of QC-LDPC coded method based on two-level pipeline it is adaptable in CMMB system 3/4 Code check QC-LDPC code, its coding step is described as follows：

1st step, calculates vectorial s using the multiplier of sparse matrix and vector；

2nd step, calculates the vectorial p of verification using the multiplier of vector and high-density matrix.

When Fig. 5 summarizes the hardware resource consumption needed for each coding step of encoder and whole cataloged procedure and processes Between.

It is not difficult to find out from Fig. 5, when streamline is full of, whole cataloged procedure needs max (t c+b, cb)=cb clock week altogether Phase, less than the e × b clock cycle needed for the serial encoding method based on c SRAA-I circuit.For in CMMB standard 3/4 Code check QC-LDPC encoder, the coding rate of the present invention is 3 times of the latter.

In CMMB standard, the existing solution of 3/4 code check QC-LDPC encoder needs e × c × b bit ROM, and this Bright need c²B bit ROM.The present invention needs less ROM, is the 1/3 of existing solution.

As fully visible, for 3/4 code check QC-LDPC encoder in CMMB standard, compared with traditional serial SRAA method, this Invention has the advantages that coding rate is fast, memory consumption few.

The above, only one of specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, Any those of ordinary skill in the art disclosed herein technical scope in, the change that can expect without creative work Change or replace, all should be included within the scope of the present invention.Therefore, protection scope of the present invention should be with claims The protection domain being limited is defined.

Claims (4)

1. the QC-LDPC encoder based on two-level pipeline in a kind of CMMB, the check matrix H of 3/4 code check QC-LDPC code be by The array that c × t b × b rank circular matrix is constituted, wherein, c=9, t=36, b=256, e=t-c=27, check matrix H can It is divided into 2 submatrixs, H=[C D], C are to be made up of c × e b × b rank circular matrix, D is to be circulated by c × c b × b rank Matrix is constituted, Φ^T=D^–1, wherein, subscript^TWith^-1Represent transposition and inverse, Matrix C corresponding informance vector a respectively, matrix D corresponds to school Test vectorial p, with b bit for one section, information vector a is divided into e section, i.e. a=(a₁,a₂,…,a_e), vectorial p is halved for verification For c section, i.e. p=(p₁,p₂,…,p_c), s^T=Ca^T, p=s Φ, vectorial s is divided into c section, i.e. s=(s₁,s₂,…,s_c), it is special Levy and be, described encoder is included with lower component：

Sparse matrix and vectorial multiplier, by t b bit register R_1,1,R_1,2,…,R_1,tWith c multi input XOR gate X_1,1,X_1,2,…,X_1,cComposition, for calculating vectorial s；

Vector and the multiplier of high-density matrix, move to right cumulative mechanism based on part parallel input, many by shift register, generation Item formula look-up table, b position binary multiplier, b position binary adder and accumulator composition, for calculating the vectorial p of verification, shift Register pair array section s_jRing shift right, generator polynomial look-up table L₁,L₂,…,L_cPrestore matrix Φ the 1,2nd respectively ..., c block All circular matrix generator polynomials in row, generator polynomial look-up table L₁,L₂,…,L_cThe generator polynomial bit of output divides Other and shift register content carries out scalar multiplication, and this c scalar multiplication passes through b position binary multiplier M respectively₁,M₂,…,M_c Complete, b position binary multiplier M₁,M₂,…,M_cProduct respectively with accumulator R₁,R₂,…,R_cContent be added, this c mould 2 Addition passes through b position binary adder A respectively₁,A₂,…,A_cComplete, b position binary adder A₁,A₂,…,A_cAnd deposit respectively Enter accumulator R₁,R₂,…,R_c, wherein, 1≤j≤c.

2. in a kind of CMMB according to claim 1 the QC-LDPC encoder based on two-level pipeline it is characterised in that Described sparse matrix is as follows with the step of the vectorial s of multiplier calculating of vector：

1st step, input information section a₁,a₂,…,a_e, they are stored in respectively depositor R_1,1,R_1,2,…,R_1,eIn；

2nd step, depositor R_1,1,R_1,2,…,R_1,eRing shift left 1 time simultaneously, XOR gate X_1,1,X_1,2,…,X_1,cRespectively by XOR Result moves to left into depositor R_1,e+1,R_1,e+2,…,R_1,tIn；

3rd step, repeats the 2nd step b-1 time, after the completion of, depositor R_1,e+1,R_1,e+2,…,R_1,tThe content of storage is array section respectively s₁,s₂,…,s_c, they constitute vectorial s.

3. in a kind of CMMB according to claim 1 the QC-LDPC encoder based on two-level pipeline it is characterised in that Described vector is as follows with the step of the vectorial p of multiplier calculating verification of high-density matrix：

1st step, resets accumulator R₁,R₂,…,R_c；

2nd step, shift register input vector section s_j, wherein, 1≤j≤c；

3rd step, generator polynomial look-up table L₁,L₂,…,L_cRespectively the 1,2nd in output matrix Φ jth block row ..., the life of c block row Become multinomial bit, these generator polynomial bits pass through b position binary multiplier M respectively₁,M₂,…,M_cWith shift register Content carry out scalar multiplication, b position binary multiplier M₁,M₂,…,M_cProduct respectively pass through b position binary adder A₁, A₂,…,A_cWith accumulator R₁,R₂,…,R_cContent be added, b position binary adder A₁,A₂,…,A_cAnd respectively be stored in cumulative Device R₁,R₂,…,R_c；

4th step, shift register ring shift right one, repeats the 3rd step b-1 time；

5th step, is incremented by, with 1 for step-length, the value changing j, repeats the 2nd～4 step c-1 time, until entirely vectorial s input finishes, this When, accumulator R₁,R₂,…,R_cStorage is verification section p respectively₁,p₂,…,p_c, they constitute the vectorial p=(p of verification₁, p₂,…,p_c).

4. the QC-LDPC coded method based on two-level pipeline in a kind of CMMB, the check matrix H of 3/4 code check QC-LDPC code is The array being made up of c × t b × b rank circular matrix, wherein, c=9, t=36, b=256, e=t-c=27, check matrix H 2 submatrixs can be divided into, H=[C D], C are to be made up of c × e b × b rank circular matrix, and D is to be followed by c × c b × b rank Ring matrix is constituted, Φ^T=D^–1, wherein, subscript^TWith^-1Represent transposition and inverse, Matrix C corresponding informance vector a respectively, matrix D corresponds to The vectorial p of verification, with b bit for one section, information vector a is divided into e section, i.e. a=(a₁,a₂,…,a_e), the vectorial p of verification by etc. It is divided into c section, i.e. p=(p₁,p₂,…,p_c), s^T=Ca^T, p=s Φ, vectorial s is divided into c section, i.e. s=(s₁,s₂,…,s_c), its It is characterised by, described coded method comprises the following steps：

1st step, calculates vectorial s using the multiplier of sparse matrix and vector；

2nd step, calculates the vectorial p of verification using the multiplier of vector and high-density matrix.