CN102104441A - Data transmission method, system and relay device - Google Patents

Abstract

The embodiment of the invention provides a data transmission method, a data transmission system and a relay device. The method comprises the following steps of: receiving data from at least two source nodes; decoding the data respectively, performing joint coding on the decoded data and acquiring a check bit; and transmitting the check bit to a destination node, wherein the check bit is used for performing joint decoding on the data received by the destination node from the at least two source nodes by the destination node. In the embodiment of the invention, when forwarding the data transmitted by the source nodes, the relay device performs the joint coding on the decoded data, transmits the acquired check bit to the destination node and does not transmit repeatedly coded data to the destination node, so the destination node is endowed with relatively higher error correcting capability when performing the joint decoding on the coded data transmitted by the source nodes and the check bit transmitted by the relay device.

Description

Data transmission method for uplink and system and relay

Technical field

The embodiment of the invention relates to the communications field, relates in particular to a kind of data transmission method for uplink and system and relay.

Background technology

Utilize via node to assist travelling carriage to transmit data, can obtain extra diversity gain, improve receiving terminal bit error rate (Bit Error Ratio, hereinafter to be referred as: BER), be to improve travelling carriage in one of effective means of cell edge speech quality.On via node, adopt network coding technique, then can further improve the forward efficiency of via node.

Suppose to exist source node S 1 and S2, in the prior art, source node S 1 and S2 can send information to via node and destination node, and this information is for (Low Density ParityCheck is hereinafter to be referred as the LDPC) information behind the coding through low-density checksum.For via node, can carry out LDPC decoding to the information of source node S 1 and S2 transmission respectively, respectively the information of S1 after the decoding and S2 transmission is carried out the LDPC coding again, after the data of carrying out S1 that LDPC coding obtains and S2 are once more carried out mould two and computing, send to destination node, this is equivalent to and utilizes a plurality of subcodes of coding and decoding that can independently realize to constitute a supersign, generally is referred to as nested code.

In realizing process of the present invention, the inventor finds that there are the following problems at least in the prior art: the coded message of source node needs repeated encoding on via node, sends to destination node then, thereby causes error correcting capability relatively poor.

Summary of the invention

The embodiment of the invention provides a kind of data transmission method for uplink and system and relay.

The embodiment of the invention provides a kind of data transmission method for uplink, comprising:

Receive the data that at least two source nodes send;

Described data are decoded respectively, and decoded data are carried out combined coding, obtain check bit;

Described check bit is sent to destination node, and described check bit is used for described destination node the data of described at least two source nodes transmission of described destination node reception is carried out joint decoding.

The embodiment of the invention provides a kind of relay, comprising:

Receiver module is used to receive the data that at least two source nodes send;

Coding/decoding module is used for described data are decoded respectively, and decoded data is carried out combined coding, obtains check bit;

Sending module sends to destination node with described check bit, and described check bit is used for described destination node the data of described at least two source nodes transmission of described destination node reception are carried out joint decoding.

The embodiment of the invention provides a kind of data Transmission system, comprises above-mentioned relay.

The embodiment of the invention, when relay is transmitted processing in the data that source node is sent, can carry out combined coding to decoded data, and the check bit that obtains sent to destination node, but not the data behind the repeated encoding are sent to destination node, thereby the check bit that makes destination node to send according to the coded data and the relay of source node transmission carries out joint decoding, and then can obtain higher error correcting capability.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do one to the accompanying drawing of required use in embodiment or the description of the Prior Art below introduces simply, apparently, accompanying drawing in describing below is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the flow chart of an embodiment of data transmission method for uplink of the present invention;

The system model schematic diagram of Fig. 2 another embodiment of data transmission method for uplink of the present invention;

Fig. 3 is a principle schematic embodiment illustrated in fig. 2;

Fig. 4 is the Tanner figure of middle network LDPC sign indicating number embodiment illustrated in fig. 2;

Fig. 5 is a simulation result figure of middle network LDPC sign indicating number embodiment illustrated in fig. 2;

Fig. 6 is the structural representation of an embodiment of relay of the present invention;

Fig. 7 is the structural representation of another embodiment of relay of the present invention;

Fig. 8 is the structural representation of data Transmission system embodiment of the present invention.

Embodiment

For the purpose, technical scheme and the advantage that make the embodiment of the invention clearer, below in conjunction with the accompanying drawing in the embodiment of the invention, technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.

Fig. 1 is the flow chart of an embodiment of data transmission method for uplink of the present invention, and as shown in Figure 1, the method for present embodiment can comprise:

The data that step 101, at least two source nodes of reception send;

For instance, relay can receive the data that at least two source nodes send.

Source node can divide two stages to finish to the transfer of data of destination node: the phase I is that source node sends data to destination node and relay; Second stage is that relay sends the corresponding check bit of data that sends with source node to destination node.In the present embodiment, in phase I, source node can adopt the form of time division multiple access or frequency division multiple access or code division multiple access to send data, and each source node can adopt the loe-density parity-check code that can approach the channel capacity limit as channel coding method, for example the LDPC sign indicating number.

Step 102, described data are decoded respectively, and decoded data are carried out combined coding, obtain check bit;

In second stage, relay can be decoded to the data that receive earlier, for example carry out the LDPC decoding, thereby can obtain the estimated information corresponding respectively with the data of each source node transmission, relay can be to decoded data then, be that estimated information carries out combined coding, obtain check bit, and these check bits are transmitted to destination node.

Step 103, described check bit is sent to destination node, described check bit is used for the data that described at least two source nodes that described destination node receives described destination node send and carries out joint decoding.

Relay can send to destination node with this check bit, and the data that destination node can send according to the check bit and the source node of relay transmission are carried out joint decoding, thereby obtain the decoded data that source node sends.Destination node is that the LDPC sign indicating number that check bit that coded data that source node is sent and relay send is regarded an integral body as is deciphered, and promptly adopts network low-density checking codes to decipher.

Because when relay is transmitted processing in the data that source node is sent, be that decoded data are carried out combined coding, and the check bit that combined coding obtains sent to destination node, but not the data behind the repeated encoding are sent to destination node, thereby when making the check bit of coded data that destination node sends source node and relay transmission carry out joint decoding, can obtain higher error correcting capability.

Be elaborated with the technical scheme of a specific embodiment below to data transmission method for uplink of the present invention.

The system model schematic diagram of Fig. 2 another embodiment of data transmission method for uplink of the present invention, Fig. 3 are principle schematic embodiment illustrated in fig. 2, shown in Fig. 2 and 3, comprise 2 source node S in the wireless relay network shown in this system model schematic diagram ₁And S ₂, 1 via node R and 1 destination node D, need to prove that two source nodes that data transmission method for uplink of the present invention is not limited to adopt in the present embodiment can also have more multiple source node as required.Present embodiment can suppose that source node, via node R and destination node D all have an antenna.Source node S ₁And S ₂To the transfer of data of destination node D, divide two stages to finish: the phase I is a source node S ₁And S ₂To destination node D and via node R broadcast data; Second stage is that via node R transmits and source node S to destination node D ₁And S ₂The data corresponding check bit that sends.

In phase I, two source nodes adopt any form transmission data in time division multiple access, frequency division multiple access or the code division multiple access, and each source node adopts the loe-density parity-check code that can approach the channel capacity limit as channel coding method, the data that via node R received in the phase I can be as the formula (1), and the data that destination node D received in the phase I can be as the formula (2):

$y_{S_{i}R}\left(t\right)=h_{S_{i}R}{x}_i\left(t\right)+n_{S_{i}R}\left(t\right)---\left(1\right)$

$y_{S_{i}D}\left(t\right)=h_{S_{i}D}{x}_i\left(t\right)+n_{S_{i}D}\left(t\right)---\left(2\right)$

Wherein, i=1,2, t=1,2, Λ, The source node S that expression via node R receives in t time slot _iData,

Expression destination node D source node S in t time slot _iData, x _i(t) expression source node S _iThe data that in t time slot, send,

The expression source node S _iAnd the channel fading matrix between the destination node D, The expression source node S _iAnd the channel fading matrix between the via node R, and Obeying average is zero, and variance is σ _SD ²Multiple Gaussian Profile,

Obeying average is zero, and variance is σ _SR ²Multiple Gaussian Profile.

Be source node S _iAnd the channel additive noise between the via node R, obeying average is zero, variance N _SR ²Multiple Gaussian Profile,

Be source node S _iAnd the channel additive noise between the via node D, obeying average is zero, variance N _SD ²Multiple Gaussian Profile.

In second stage, via node R is at first according to the data of receiving

Decode, obtain the estimated information of two source nodes With

And the estimated information of two source nodes carried out combined coding, obtain k ₂Individual check bit, and these check bits are transmitted to destination node D.The data that this moment, destination node D received can be as the formula (3):

y _RD(t)＝h _RDx _R(t)+n _RD(t) (3)

T=n wherein, n+1, Λ, n+k ₂, h _RDChannel fading coefficient between expression via node R and the destination node D, obeying average is zero, variance is σ _RD ²Multiple Gaussian Profile, n _RD(t) be channel additive noise between via node R and the destination node D, obeying average is zero, variance N _RD ²Multiple Gaussian Profile.

In second stage, via node R decodes respectively to the data that source node sends, and decoded data are carried out combined coding, obtain check bit, therefore, middle step 102 embodiment illustrated in fig. 1 can comprise: the structure chart of using low density parity check code, obtain described check bit, described structure chart comprises a * k ₁Individual upper strata check-node, k ₂Individual lower floor check-node, a * n the variable node that is connected respectively with described upper strata check-node and lower floor check-node and the k that is connected with described lower floor check-node ₂Individual check-node, wherein a is the number of source node, described a * k ₁Individual upper strata check-node is used to import a * k that a source node sends respectively ₁Individual bit, described a * n variable node are used for output to a * k ₁A * the n that obtains after individual bit is decoded variable bit, described k ₂Individual check-node is used to export a * n the variable bit that decoding is obtained and carries out the check bit that combined coding obtains.

More specifically, use the structure chart of low density parity check code, the method for obtaining described check bit can comprise: determine a * k according to the degree distribution function ₁First line relation and k between individual upper strata check-node and a * n variable node ₂An individual lower floor check-node and a * n variable node and k ₂Second line relation between the individual check-node, wherein a is the number of source node, a * k ₁Individual upper strata check-node is used to import the k that a source node sends respectively ₁Individual Bit data; According to described first line relation, determine a * k ₁Individual equation, described a * k ₁The Bit data that the variable bit sum of the variable node that each The Representation Equation is connected with a upper strata check-node in the individual equation equals this upper strata check-node input obtains a * n variable bit by solving an equation;

According to described second line relation, determine k ₂Individual equation, described k ₂Described variable bit that obtains on each The Representation Equation and the variable node that lower floor's check-node is connected in the individual equation and the unknown check bit sum on the check-node equal zero, and obtain k by solving an equation ₂Individual check bit.In the present embodiment, a=2 promptly has two source nodes.

Adopt a computation model to the above-mentioned k that obtains below ₂The process of individual check bit is elaborated, and also is the implementation procedure in the frame of broken lines among Fig. 3.

Fig. 4 is the Tanner figure of middle network LDPC sign indicating number embodiment illustrated in fig. 2, and as shown in Figure 4, the Tanner figure of the network LDPC sign indicating number of present embodiment has following two characteristics:

The one, the Tanner figure of network LDPC sign indicating number is made of two-layer check-node and one deck variable node, its at the middle and upper levels the check-node number be 2k ₁, lower floor's check-node number is k ₂, the variable node number is 2n+k ₂, 2n+k wherein ₂Variable node comprise 2n variable node and k ₂Individual check-node.

The 2nd, among the Tanner figure of network LDPC sign indicating number, each variable node has two degree, with (wherein i goes up depth, the limit number that the expression variable node is connected with the upper strata check-node for i, j) expression; J is following depth, the limit number that the expression variable node is connected with the lower floor check-node.Expenditure distribution function λ _{I, j}Expression is that (i, the limit number that variable node j) connects accounts for the ratio of total limit number with degree.Present embodiment can suppose that the degree of upper strata check-node is fixed as d _c, the degree of lower floor's check-node is fixed as d ' _c, i represents the degree of variable node in first figure among Fig. 4, j represents the degree of variable node in second figure.Therefore, the degree d by the upper strata check-node _cAnd variable node can determine described first line relation at the degree i of first figure, by the degree d ' of lower floor's check-node _cAnd variable node can be determined described second line relation at the degree j of second figure.

In Fig. 4, the variable node and the 2k of 2n circle representative in the middle of first line relation is ₁Annexation between the check-node of individual upper strata, the variable node and the k of 2n circle representative in the middle of second line relation is ₂The check-node and the k of individual circle representative ₂Annexation between the individual lower floor check-node.Wherein, has only 2k ₁The 2k that 2 source nodes of individual upper strata check-node input send ₁Bit data is known.For each upper strata check-node, the variable bit sum of the unknown of connected variable node equals the Bit data of this upper strata check-node input, promptly can set up an equation for this upper strata check-node.By that analogy, for 2k ₁Individual upper strata check-node can be set up 2k ₁Individual equation can obtain the 2k corresponding respectively with 2n variable node by solving an equation ₁Individual variable bit, wherein n=k ₁For each lower floor's check-node, the Bit data sum on connected variable node and the check-node is zero, therefore, can set up an equation for this lower floor's check-node.By that analogy, for k ₂Individual lower floor check-node can be set up k ₂Individual equation, wherein, the variable bit on the variable node passes through aforementioned 2k ₁Therefore individual equation solution obtains, at the k of lower floor's check-node ₂In the individual equation, k is only arranged ₂Bit data on the individual check-node is unknown, therefore, and by separating k ₂Individual equation can obtain k ₂Bit data on the individual check-node, the Bit data on this check-node is the Bit data that sends to destination node.

In implementation procedure, when the relaying node R receives the k that two source nodes send respectively ₁Behind the individual Bit data, can set up 2k according to first line relation ₁Equation between individual Bit data and the 2n variable node obtains 2n=2k after solving an equation ₁Individual variable bit.After obtaining 2n decoded variable bit, can set up 2n variable node and k according to second line relation ₂Equation between the individual check-node can obtain k by solving an equation ₂Check bit on the individual check-node, and with this k ₂Individual check bit sends to destination node.

In the present embodiment, in order to improve the forward efficiency of via node, when planned network LDPC sign indicating number, can be to minimize k ₂Value as design object, promptly minimum with the check bit that sends to destination node is design object, is design object with the minimum number of check-node among Fig. 4 promptly also.

Therefore, present embodiment is being determined a * k according to the degree distribution function ₁First line relation and k between individual upper strata check-node and a * n variable node ₂An individual lower floor check-node and a * n variable node and k ₂Before second line relation between the individual check-node, can also comprise: calculate and obtain default target function $\mathrm{\&eta;}=\frac{{2d}_c{k}_1}{d_c^{\&prime;}{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="H2009102580458E00023.png,H2009102580458E00033.png"\; state="\{\{state\}\}">k</figure-callout>}}_2+2{\mathrm{<figure-callout\; id="1"\; label="d\; c\; k"\; filenames="H2009102580458E00021.png,H2009102580458E00023.png"\; state="\{\{state\}\}">d</figure-callout>}}_c{k}_{}{}_1}$ The k of correspondence when getting maximum ₂Value, wherein, d _cBe the degree of described upper strata check-node, d ' _cDegree for described lower floor check-node.Via node R can store the expression formula of this this target function in advance.

The Gaussian approximation algorithm of present embodiment planned network LDPC sign indicating number can for:

m ^lAnd n ^lBe illustrated respectively in l wheel iterative decoding at first, the input message average of upper strata check-node and lower floor's check-node, the message average behind the checksum update is m ' ^lAnd n ' ^lFor log-likelihood ratio and long-pending decoding algorithm, the number of degrees are (i, the message average m after variable node j) upgrades _{I, j} ^L+1And n _{I, j} ^L+1Can be from m ' ^lAnd n ' ^lCalculate:

$m_{i,j}^{l+1}=(i-1)m^{\&prime;l}+{\mathrm{jn}}^{\&prime;l}+m_c,j\&GreaterEqual;0$

$n_{i,j}^{l+1}=\left(i\right)m^{\&prime;l}+(j+1)n^{\&prime;l}+m_c,j\&GreaterEqual;1$

Wherein, i 〉=2, m _cThe average of the log-likelihood ratio that the expression channel is received.For additive white Gaussian noise (Additive White Gaussian Noise, hereinafter to be referred as AWGN) channel, when modulation system be binary phase shift keying (Binary Phase Shift Keying, hereinafter to be referred as: in the time of BPSK), $m_c=\frac{2}{{\mathrm{\&sigma;}}^2},$ σ wherein ²The power of expression Gaussian noise.

M ' ^lAnd n ' ^lCan upgrade operational computations by following verification average obtains:

$m^{\&prime;l}=\underset{k}{\mathrm{\&Sigma;}}{\mathrm{\&rho;}}_k{\mathrm{\&phi;}}^{-1}\left({\left[\frac{1}{\mathrm{\&eta;}}\underset{i\&GreaterEqual;0,j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{i,j}\mathrm{\&phi;}\left(m_{i,j}^l\right)\right]}^{k-1}\right)$

$n^{\&prime;l}={\mathrm{\&phi;}}^{-1}\left({\left[\frac{1}{1-\mathrm{\&eta;}}\underset{i\&GreaterEqual;0,j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{j}{i+j}{\mathrm{\&lambda;}}_{i,j}\mathrm{\&phi;}\left(n_{i,j}^l\right)\right]}^{d_c^{\&prime;}}\right)$

Wherein, $\mathrm{\&phi;}\left(x\right)=\left\{\begin{array}{cc}\frac{1}{\sqrt{4\mathrm{\&pi;x}}}\underset{R}{\&Integral;}\tanh \frac{u}{2}{e}^{\frac{{(u-x)}^2}{4x}}\mathrm{du},& \mathrm{if\; x}>0\\ 0,& \mathrm{if\; x}=0\end{array}\right.$

In l+1 wheel iteration at first, the input message average of the upper and lower check-node can be calculated by following formula:

$m^{l+1}=\frac{1}{\mathrm{\&eta;}}\underset{i\&GreaterEqual;0,j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{i,j}\mathrm{\&phi;}\left(m_{i,j}^{l+1}\right)$

$n^{l+1}=\frac{1}{1-\mathrm{\&eta;}}\underset{i\&GreaterEqual;0,j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{i,j}\mathrm{\&phi;}\left(n_{i,j}^{l+1}\right)$

After the L wheel iteration, the average of the log-likelihood ratio y of code word bits is m _L=η m ^L+ (1-η) n ^L, its variance is 2m _LBecause log-likelihood ratio is an approximate Gaussian, its probability density function is:

$p\left(y\right)=\frac{1}{\sqrt{4\mathrm{\&pi;}{m}_L}}\exp (-\frac{{(y-m_L)}^2}{4m_L})$

Therefore, the error rate that can obtain designed degree sequence is

$P_e={\&Integral;}_0^{\&infin;}p\left(y\right)\mathrm{dy}=\frac{1}{2}\mathrm{erfc}\left(\sqrt{m_L/4}\right)$

This error rate is about m _LDecreasing function, work as m _LWhen enough big, the error rate will be tending towards 0.If the average of sign indicating number satisfies m _L＞M just is called and can realizes zero defect decoding.

Specifically, present embodiment can have been fixed λ _i, ρ _i, d ' _cAnd σ, η is that target is sought best degree distribution function λ with maximization _{I, j}(i, j 〉=0), i.e. λ _{I, j}The iteration planning of (i, j 〉=0) and η is upgraded and is progressively maximized η according to the methods below:

$\underset{{\mathrm{\&lambda;}}_{i,j}}{\max }\mathrm{\&eta;}=\underset{i}{\mathrm{\&Sigma;}}\underset{j}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{i,j}---\left(4\right)$

s.t. $\underset{j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{i,j}-\mathrm{\&eta;}{\mathrm{\&lambda;}}_i=0---\left(5\right)$

$\underset{i\&GreaterEqual;0,j\&GreaterEqual;}{\mathrm{\&Sigma;}}{\mathrm{\&lambda;}}_{i,j}=1---\left(6\right)$

m ^L＞M (7)

Above-mentioned optimization is a nonlinear programming problem, and present embodiment adopts two step iterative algorithms: the first step, find the degree distribution λ of an energy fast decoding _{I, j} ^f(i, j 〉=0), after L wheel iteration, its output average reaches maximum.Second step, degree of finding distribution λ _{I, j} ^*(i, j 〉=0), it can make the η value reach maximum (its maximum is 1).From initial degree distribution λ _{I, j} ^f(i, j 〉=0) is along λ _{I, j} ^*The direction of (i, j 〉=0) changes λ _{I, j}Up to do not satisfy condition (7).Current degree distribution λ _{I, j} ^Opt(i, j 〉=0) is exactly optimum.

The first step: the degree distribution λ that seeks the energy fast decoding _{I, j} ^f(i, j 〉=0):

Initialization:

At first seek initial degree distribution λ _{I, j}(i, j 〉=0), this initially spends distribution λ _{I, j} ⁰(i, j 〉=0) should satisfy:

a) ${\mathrm{\&lambda;}}_{i,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0\&NotEqual;0,$ i，j≥0，λ _i≠0；

B) λ _{I, j} ⁰(i, j 〉=0) is uniform as far as possible;

C) λ _{I, j} ⁰(i, j 〉=0) not necessarily satisfies the condition that can translate.

For simplicity, establish ${\mathrm{\&lambda;}}_{i,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0=c_i,$ j≥0。Condition (4～6) becomes:

${\mathrm{\&eta;}}^0=\underset{i}{\mathrm{\&Sigma;}}\underset{j}{\mathrm{\&Sigma;}}\frac{i}{i+j}{c}_i---\left(8\right)$

$\underset{j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{i}{i+j}{c}_i-\mathrm{\&eta;}{\mathrm{\&lambda;}}_i=0---\left(9\right)$

$\underset{i\&GreaterEqual;0,j\&GreaterEqual;0}{\mathrm{\&Sigma;}}{c}_i=1---\left(10\right)$

Fixing c ₀, just can obtain η ⁰And c _{I, i}＞0:

$c_i=\frac{{\mathrm{\&eta;}}^0{\mathrm{\&lambda;}}_i}{\underset{j}{\mathrm{\&Sigma;}}\frac{i}{i+j}}$

${\mathrm{\&eta;}}^0=\frac{1-d_v{c}_0}{(d_v+1)\underset{i\&NotEqual;0}{\mathrm{\&Sigma;}}\frac{{\mathrm{\&lambda;}}_i}{\underset{j}{\mathrm{\&Sigma;}}\frac{i}{i+j}}},$

Wherein, d _vBe the maximum number of degrees of variable node in second figure.

Upgrade λ _{I, j}(i, j 〉=0): constantly revise λ _{I, j} ⁰(i, j 〉=0) thus degree of finding distribution λ _{I, j} ^f(i, j 〉=0), the correction step is:

Step 1: given initial degree distribution λ _{I, j} ⁰(i, j 〉=0) utilizes above-mentioned Gaussian approximation algorithm, calculates the input message average m of check-node after the L wheel iteration _L ⁰(λ _{I, j} ⁰);

Step 2: for (k, l), according to giving fixed step size d, the renewal degree is distributed as ${\mathrm{\&lambda;}}_{k,l}={\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0+d;$

Step 3: adjust λ _{I, j}(i ≠ k, j ≠ l) make it satisfy formula (5～6).For satisfying formula (5～6), each λ _{I, j}(i ≠ k, j ≠ l) all will take advantage of a modifying factor c _{I, j}(i ≠ k, j ≠ l), promptly

${\mathrm{\&lambda;}}_{i,j}=c_{i,j}{\mathrm{\&lambda;}}_{i,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0,(i\&NotEqual;k,j\&NotEqual;l)$

Wherein, modifying factor c _{I, j}(i ≠ k, j ≠ l) satisfy: c _{I, j}＞0 (i ≠ k, j ≠ l) and c _{I, j}(i ≠ k, j ≠ l) equal as far as possible.Calculate for simplifying, present embodiment can only adopt two different factors:

c _{K, j}=c ₁, j ≠ l and c _{I, j}=c ₂, i ≠ k, j 〉=0

Suppose to upgrade at present λ _{K, l} ⁰, new distribution λ _{I, j}(i, j 〉=0) and λ _{I, j} ⁰The pass of (i, j 〉=0) is:

${\mathrm{\&lambda;}}_{k.l}={\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0+d---\left(11\right)$

${\mathrm{\&lambda;}}_{i,j}=c_{i,j}{\mathrm{\&lambda;}}_{i,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0,(i\&NotEqual;k,j\&NotEqual;l)$

C wherein _{I, j}(i ≠ k, j ≠ l) is a modifying factor.For simplicity, present embodiment only adopts two factors:

c _k，j＝c ₁，j≠l?and?c _i，j＝c ₂，i≠k j≥0

New degree distribution λ _{I, j}(4～6) satisfy condition (i, j 〉=0):

$\mathrm{\&eta;}={\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="H2009102580458E00021.png,H2009102580458E00023.png"\; state="\{\{state\}\}">c</figure-callout>}}_1\underset{j\&NotEqual;l}{\mathrm{\&Sigma;}}\frac{k}{k+j}{\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0+{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="H2009102580458E00023.png,H2009102580458E00033.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\underset{i\&NotEqual;k,j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{i,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0+\frac{k}{k+l}({\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0+d)---\left(12\right)$

${\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="H2009102580458E00021.png,H2009102580458E00023.png"\; state="\{\{state\}\}">c</figure-callout>}}_1\underset{j\&NotEqual;l}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0+\frac{k}{k+l}({\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0+d)-\mathrm{\&eta;}{\mathrm{\&lambda;}}_k=0---\left(13\right)$

${\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="H2009102580458E00023.png,H2009102580458E00033.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\underset{j\&GreaterEqual;0}{\mathrm{\&Sigma;}}\frac{i}{i+j}{\mathrm{\&lambda;}}_{i,j}^0-\mathrm{\&eta;}{\mathrm{\&lambda;}}_i=0,i\&NotEqual;k---\left(14\right)$

${\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="H2009102580458E00021.png,H2009102580458E00023.png"\; state="\{\{state\}\}">c</figure-callout>}}_1\underset{j\&NotEqual;l}{\mathrm{\&Sigma;}}{\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0+{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="H2009102580458E00023.png,H2009102580458E00033.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\underset{i\&NotEqual;k,j\&GreaterEqual;0}{\mathrm{\&Sigma;}}{\mathrm{\&lambda;}}_{i,\mathrm{<figure-callout\; id="0"\; label="j"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">j</figure-callout>}}^0+{\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0+d=1---\left(15\right)$

Because above-mentioned four constraintss are not independently, and unique solution can be arranged.

For k=0, condition (15) is effective.Know c by even rule ₁=c ₂Be optimum solution, therefore have

$c_1=c_2=1-\frac{d}{1-{\mathrm{\&lambda;}}_{0,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0},k=0,l\&GreaterEqual;0---\left(16\right)$

If ${\mathrm{\&lambda;}}_{0,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0+d<1,$ C then ₁=c ₂＞0.

For k ≠ 0, condition (12～15) is all effective, can solve

$c_1=1-\frac{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="H2009102580458E00021.png,H2009102580458E00023.png"\; state="\{\{state\}\}">d</figure-callout>}}{\frac{1}{1+(1-\underset{j}{\mathrm{\&Sigma;}}{\mathrm{\&lambda;}}_{k,j}^0)/\underset{j}{\mathrm{\&Sigma;}}\frac{k+l}{k+j}{\mathrm{\&lambda;}}_{k,j}^0}-{\mathrm{\&lambda;}}_{k,l}^0}---\left(17\right)$

$c_2=c_1(1-\frac{{\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0}{\underset{j}{\mathrm{\&Sigma;}}\frac{k+l}{k+j}{\mathrm{\&lambda;}}_{k,j}^0})+\frac{{\mathrm{\&lambda;}}_{k,\mathrm{<figure-callout\; id="0"\; label="l"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">l</figure-callout>}}^0+d}{\underset{j}{\mathrm{\&Sigma;}}\frac{k+l}{k+j}{\mathrm{\&lambda;}}_{k,j}^0}---\left(18\right)$

Step 4: utilize density to evolve m is calculated in each new degree distribution _L(λ _{I, j}).Compare m _L(λ _{I, j}) and m _L ⁰(λ _{I, j} ⁰), if $m_L\left({\mathrm{\&lambda;}}_{i,j}\right)>m_L^0\left({\mathrm{\&lambda;}}_{i,j}^0\right),$ Just degree distribution λ _{I, j}(i, j 〉=0) is used as new initial distribution λ _{I, j} ⁰(i, j 〉=0), it also is the degree distribution of current energy fast decoding.Otherwise, abandon λ _{I, j}(i, j 〉=0), the direction of change d.Check whether satisfy end condition (enough big), if satisfy then current degree distribution λ such as average _{I, j}(i, j 〉=0) is exactly the degree distribution of energy fast decoding, otherwise execution in step 2.

Second step: seek the decodable degree distribution λ that makes the η maximum _{I, j} ^Opt(i, j 〉=0)

Searching makes the degree distribution λ of η=1 _{I, j} ^*(i, j 〉=0) ignores condition (7), maximizes the η of only satisfy condition (4～6), and this problem deteriorates to linear programming problem.So λ _{I, j} ^*(i, j 〉=0) can be tried to achieve by simplex method.

Seek λ _{I, j} ^OptThe method of (i, j 〉=0) is:

From initial distribution λ _{I, j} ^f(i, j 〉=0) is along λ _{I, j} ^*The direction of (i, j 〉=0) changes λ _{I, j}Up to do not satisfy condition (7).

This is equivalent to seeks the t that satisfies following condition ^*:

$\left[{\mathrm{\&lambda;}}_{i,j}\right]=\left[{\mathrm{\&lambda;}}_{i,j}^f\right]+t\left(\right[{\mathrm{\&lambda;}}_{i,j}^{*}]-[{\mathrm{\&lambda;}}_{i,j}^f\left]\right),(i,j\&GreaterEqual;0),0\&le;t^{*}\&le;1---\left(19\right)$

$t^{*}=\underset{0\&le;t\&le;1}{\mathrm{<figure-callout\; id="0"\; label="max"\; filenames="H2009102580458E00023.png"\; state="\{\{state\}\}">max</figure-callout>}}\left\{t\right|m_L\left({\mathrm{\&lambda;}}_{i,j}\right)>M\}$

Easily demonstrate,prove

(i, j 〉=0) satisfies the linear conditions of formula (5～6), therefore

$\left[{\mathrm{\&lambda;}}_{i,j}^{\mathrm{opt}}\right]=\left[{\mathrm{\&lambda;}}_{i,j}^f\right]+t^{*}\left(\right[{\mathrm{\&lambda;}}_{i,j}^{*}]-[{\mathrm{\&lambda;}}_{i,j}^f\left]\right)---\left(20\right)$

According to the method described above, it is as follows to obtain one group of examples of parameters of LDPC sign indicating number:

(1) two source node adopts identical LDPC sign indicating number, and code length is 22164, and code check is 1/2, and the degree distribution function is:

λ(x)＝0.23403x+0.21242x ²+0.1469x ⁵+0.102840x ⁶+0.30381x ¹⁹

ρ(x)＝0.71875x ⁷+0.28125x ⁸

(2) utilize aforementioned Gaussian approximation algorithm, optimize LDPC sign indicating number shown in Figure 4, obtaining via node needs 2804 check equations, i.e. k ₂=2804, η=0.915182, and the degree sequence λ of variable node _{I, j}Be distributed as:

λ _0，2＝0.028043，

λ _2，0＝0.188139，λ _2，1＝0.019382，λ _2，2＝0.026283

λ _3，0＝0.191239，λ _3，1＝0.00336，λ _3，2＝0.00115

λ _6，0＝0.085989，λ _6，1＝0.00098，λ _6，2＝0.063446

λ _7，0＝0.059576，λ _7，2＝0.044374

λ _20，0＝0.176218，λ _20，1＝0.00357，λ _20，2＝0.108251

Therefore, via node R can adopt the above-mentioned network LDPC sign indicating number of designing to obtain check bit, then check bit is sent to destination node D.At last, the signal that can receive according to two stages of destination node D

And y _RD(t) unite iterative decoding, obtain source node S ₁And source node S ₂The data of transmission.

Fig. 5 is a simulation result figure of middle network LDPC sign indicating number embodiment illustrated in fig. 2, as shown in Figure 5, wherein suppose relay node to the signal to noise ratio of destination node is fixed as 3dB, two source nodes are to the channel symmetry of via node, and suppose to realize error free transmission between source node and the via node that two source node to destination nodes are Gaussian channels of symmetry.The code length of the LDPC sign indicating number that source node adopts is 22164, and it is that two source nodes are transmitted data simultaneously that via node utilizes 2804 extra check bits to realize, source node and via node all adopt the BPSK modulation.Abscissa is the signal to noise ratio of source node to destination node, and ordinate is a bit error rate.As seen from Figure 5, be 10 in bit error rate ^-5The time, the gap of about 0.6dB is arranged between the performance of designed sign indicating number and the threshold value.Can predict, along with the increase of code length, this gap also can further be dwindled.

In the present embodiment, because when via node is transmitted processing in the data that source node is sent, adopt network LDPC sign indicating number that decoded data are carried out combined coding, thereby obtain check bit, then this check bit is sent to destination node, but not the data behind the repeated encoding are sent to destination node, thereby when making the check bit of coded data that destination node sends source node and relay transmission carry out joint decoding, can obtain higher error correcting capability.Experiment shows that the error rate of present embodiment when coding and decoding approaches zero, thereby has effectively improved error correcting capability.

One of ordinary skill in the art will appreciate that: all or part of step that realizes said method embodiment can be finished by the relevant hardware of program command, aforesaid program can be stored in the computer read/write memory medium, this program is carried out the step that comprises said method embodiment when carrying out; And aforesaid storage medium comprises: various media that can be program code stored such as ROM, RAM, magnetic disc or CD.

Fig. 6 is the structural representation of an embodiment of relay of the present invention, as shown in Figure 6, the relay of present embodiment can comprise: receiver module 11, coding/decoding module 12 and sending module 13, receiver module 11 are used to receive the data that at least two source nodes send; Coding/decoding module 12 is used for described data are decoded respectively, and decoded data are carried out combined coding, obtains check bit; Sending module 13 is used for described check bit is sent to destination node, and described check bit is used for described destination node the data of described at least two source nodes transmission of described destination node reception are carried out joint decoding.

The relay of present embodiment is identical with the realization principle of data transmission method for uplink embodiment shown in Figure 1, repeats no more.

When the relay of present embodiment is transmitted processing in the data that source node is sent, decoded data are carried out combined coding, and the check bit that obtains sent to destination node, but not the data behind the repeated encoding are sent to destination node, thereby when making the check bit of coded data that destination node sends source node and relay transmission carry out joint decoding, can obtain higher error correcting capability.

Fig. 7 is the structural representation of another embodiment of relay of the present invention, and as shown in Figure 7, in the present embodiment, coding/decoding module 12 is used to use the structure chart of low density parity check code, obtains described check bit, and described structure chart comprises a * k ₁Individual upper strata check-node, k ₂Individual lower floor check-node, a * n the variable node that is connected respectively with described upper strata check-node and lower floor check-node and the k that is connected with described lower floor check-node ₂Individual check-node, wherein a is the number of source node, described a * k ₁Individual upper strata check-node is used to import a * k that a source node sends respectively ₁Individual bit, described a * n variable node are used for output to a * k ₁A * the n that obtains after individual bit is decoded variable bit, described k ₂Individual check-node is used to export a * n the variable bit that decoding is obtained and carries out the check bit that combined coding obtains.

Particularly, this coding/decoding module 12 can be determined a * k according to the degree distribution function ₁First line relation and k between individual upper strata check-node and a * n variable node ₂An individual lower floor check-node and a * n variable node and k ₂Second line relation between the individual check-node, wherein a is the number of source node, a * k ₁Individual upper strata check-node is used to import the k that a source node sends respectively ₁Individual Bit data; According to described first line relation, determine a * k ₁Individual equation, described a * k ₁The Bit data that the variable bit sum of the variable node that each The Representation Equation is connected with a upper strata check-node in the individual equation equals this upper strata check-node input obtains a * n variable bit by solving an equation; According to described second line relation, determine k ₂Individual equation, described k ₂Described variable bit that obtains on each The Representation Equation and the variable node that lower floor's check-node is connected in the individual equation and the unknown check bit sum on the check-node equal zero, and obtain k by solving an equation ₂Individual check bit; This relay can further include: calculate acquisition module 14, be used to calculate and obtain default target function $\mathrm{\&eta;}=\frac{2d_c{k}_1}{d_c^{\&prime;}{k}_2+2d_c{k}_1}$ The k of correspondence when getting maximum ₂Value, wherein, d is the degree of described upper strata check-node, d ' _cDegree for described lower floor check-node.

The relay of present embodiment is identical with the realization principle of the data transmission method for uplink embodiment shown in Fig. 2～5, repeats no more.

When the relay of present embodiment is transmitted processing in the data that source node is sent, adopt network LDPC sign indicating number that decoded data are carried out combined coding, thereby obtain check bit, then this check bit is sent to destination node, but not the data behind the repeated encoding are sent to destination node, thereby when making the check bit of coded data that destination node sends source node and relay transmission carry out joint decoding, can obtain higher error correcting capability.Experiment shows that the error rate of present embodiment when coding and decoding approaches zero, thereby has effectively improved error correcting capability.

Fig. 8 is the structural representation of data Transmission system embodiment of the present invention, as shown in Figure 8, the system of present embodiment can comprise: (hypothesis has two source nodes at least two source nodes 1 in the present embodiment, more multiple source node can certainly be arranged), be used for sending data to destination node 3 and relay 2; Relay 2 is used to receive the data that described at least two source nodes 1 send; Described data are decoded respectively, and decoded data are carried out combined coding, obtain check bit; Described check bit is sent to destination node 3; Destination node 3 is used for the data of described check bit and 1 transmission of described at least two source nodes are carried out joint decoding, obtains described data.

The system of present embodiment, it realizes that schematic diagram can be as shown in Figure 3.The system of present embodiment is identical with the realization principle of the data transmission method for uplink embodiment shown in Fig. 1～5, is not giving unnecessary details.

In the system of present embodiment, when relay is transmitted processing in the data that source node is sent, adopt network LDPC sign indicating number that decoded data are carried out combined coding, thereby obtain check bit, then this check bit is sent to destination node, but not the data behind the repeated encoding are sent to destination node, thereby when making the check bit of coded data that destination node sends source node and relay transmission carry out joint decoding, can obtain higher error correcting capability.Experiment shows that the error rate of present embodiment when coding and decoding approaches zero, thereby has effectively improved error correcting capability.

It should be noted that at last: above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that: it still can be made amendment to the technical scheme that aforementioned each embodiment put down in writing, and perhaps part technical characterictic wherein is equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution break away from the spirit and scope of various embodiments of the present invention technical scheme.

Claims (10)

1. a data transmission method for uplink is characterized in that, comprising:

Receive the data that at least two source nodes send;

Described data are decoded respectively, and decoded data are carried out combined coding, obtain check bit;

Described check bit is sent to destination node, and described check bit is used for described destination node the data of described at least two source nodes transmission of described destination node reception is carried out joint decoding.

2. data transmission method for uplink according to claim 1 is characterized in that, described described data is decoded respectively, and decoded data are carried out combined coding, obtains check bit, comprising:

Use the structure chart of low density parity check code, obtain described check bit, described structure chart comprises a * k ₁Individual upper strata check-node, k ₂Individual lower floor check-node, a * n the variable node that is connected respectively with described upper strata check-node and lower floor check-node and the k that is connected with described lower floor check-node ₂Individual check-node, wherein a is the number of source node, described a * k ₁Individual upper strata check-node is used to import a * k that a source node sends respectively ₁Individual bit, described a * n variable node are used for output to a * k ₁A * the n that obtains after individual bit is decoded variable bit, described k ₂Individual check-node is used to export a * n the variable bit that decoding is obtained and carries out the check bit that combined coding obtains.

3. data transmission method for uplink according to claim 2 is characterized in that, the structure chart of described application low density parity check code obtains described check bit, comprising:

Determine a * k according to the degree distribution function ₁First line relation and k between individual upper strata check-node and a * n variable node ₂An individual lower floor check-node and a * n variable node and k ₂Second line relation between the individual check-node, wherein a is the number of source node, a * k ₁Individual upper strata check-node is used to import the k that a source node sends respectively ₁Individual Bit data;

According to described first line relation, determine a * k ₁Individual equation, described a * k ₁The Bit data that the variable bit sum of the variable node that each The Representation Equation is connected with a upper strata check-node in the individual equation equals this upper strata check-node input obtains a * n variable bit by solving an equation;

According to described second line relation, determine k ₂Individual equation, described k ₂Described variable bit that obtains on each The Representation Equation and the variable node that lower floor's check-node is connected in the individual equation and the unknown check bit sum on the check-node equal zero, and obtain k by solving an equation ₂Individual check bit.

4. data transmission method for uplink according to claim 3 is characterized in that, described according to the degree distribution function determine a * k ₁First line relation and k between individual upper strata check-node and a * n variable node ₂An individual lower floor check-node and a * n variable node and k ₂Before second line relation between the individual check-node, also comprise:

Default target function is obtained in calculating $\mathrm{\&eta;}=\frac{2d_c{k}_1}{d_c^{\&prime;}{k}_2+2d_c{k}_1}$ The k of correspondence when getting maximum ₂Value, wherein, d _cBe the degree of described upper strata check-node, d ' _cDegree for described lower floor check-node.

5. data transmission method for uplink according to claim 4 is characterized in that default target function is obtained in described calculating $\mathrm{\&eta;}=\frac{2d_c{k}_1}{d_c^{\&prime;}{k}_2+2d_c{k}_1}$ The k of correspondence when getting maximum ₂Value comprises:

Adopt the Generalized Gaussian approximate data to calculate and obtain target function $\mathrm{\&eta;}=\frac{2d_c{k}_1}{d_c^{\&prime;}{k}_2+2d_c{k}_1}$ Default target function is obtained in the calculating of correspondence when getting maximum $\mathrm{\&eta;}=\frac{2d_c{k}_1}{d_c^{\&prime;}{k}_2+2d_c{k}_1}$ The k of correspondence when getting maximum ₂Value.

6. a relay is characterized in that, comprising:

Receiver module is used to receive the data that at least two source nodes send;

Coding/decoding module is used for described data are decoded respectively, and decoded data is carried out combined coding, obtains check bit;

Sending module sends to destination node with described check bit, and described check bit is used for described destination node the data of described at least two source nodes transmission of described destination node reception are carried out joint decoding.

7. relay according to claim 6 is characterized in that described coding/decoding module is used to use the structure chart of low density parity check code, obtains described check bit, and described structure chart comprises a * k ₁Individual upper strata check-node, k ₂Individual lower floor check-node, a * n the variable node that is connected respectively with described upper strata check-node and lower floor check-node and the k that is connected with described lower floor check-node ₂Individual check-node, wherein a is the number of source node, described a * k ₁Individual upper strata check-node is used to import a * k that a source node sends respectively ₁Individual bit, described a * n variable node are used for output to a * k ₁A * the n that obtains after individual bit is decoded variable bit, described k ₂Individual check-node is used to export a * n the variable bit that decoding is obtained and carries out the check bit that combined coding obtains.

8. relay according to claim 7 is characterized in that, described coding/decoding module specifically is used for determining a * k according to the degree distribution function ₁First line relation and k between individual upper strata check-node and a * n variable node ₂An individual lower floor check-node and a * n variable node and k ₂Second line relation between the individual check-node, wherein a is the number of source node, a * k ₁Individual upper strata check-node is used to import the k that a source node sends respectively ₁Individual Bit data; According to described first line relation, determine a * k ₁Individual equation, described a * k ₁The Bit data that the variable bit sum of the variable node that each The Representation Equation is connected with a upper strata check-node in the individual equation equals this upper strata check-node input obtains a * n variable bit by solving an equation;

According to described second line relation, determine k ₂Individual equation, described k ₂Described variable bit that obtains on each The Representation Equation and the variable node that lower floor's check-node is connected in the individual equation and the unknown check bit sum on the check-node equal zero, and obtain k by solving an equation ₂Individual check bit.

9. according to claim 7 or 8 described relays, it is characterized in that, also comprise:

Calculate acquisition module, be used to calculate and obtain default target function $\mathrm{\&eta;}=\frac{2d_c{k}_1}{d_c^{\&prime;}{k}_2+2d_c{k}_1}$ The k of correspondence when getting maximum ₂Value, wherein, d _cBe the degree of described upper strata check-node, d ' _cDegree for described lower floor check-node.

10. a data Transmission system is characterized in that, comprises the described relay of arbitrary claim in the claim 6～9.

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