CN103078716B - Based on the relay transmission method of distributed 3-D Turbo code - Google Patents

Abstract

The invention discloses a kind of based on 3-D? the relay transmission method of Turbo code, mainly solves the problem that existing Distributed T urbo code frame error rate is higher.Implementation step is: source node broadcast data; Via node first carries out Turbo decoding to the received signal, again the Turbo code coding identical with source node is carried out to the information translated, then carry out the coding of the third dimension with infiltration coefficient selection check bit, after the check bit modulation that the third dimension is exported, be sent to destination node; Does destination node, after receiving the information of relay transmission, carry out 3-D together with the source information received? Turbo code decoding.The present invention is by modulation intermediate position and change infiltration coefficient, can realize effective compromise of decoding performance and relaying complexity, can be used for wireless multiple access access junction network.

Description

Based on the relay transmission method of distributed 3-D Turbo code

Technical field

The invention belongs to wireless communication technology field, relate to chnnel coding and relay transmission, is exactly a kind of method 3-DTurbo code being applied to relay transmission specifically.

Background technology

Utilizing via node to help mobile subscriber forwarding data, can obtain extra diversity gain, improve the frame error rate performance of receiving terminal, is improve the effective means one of of mobile subscriber in cell edge speech quality.

Existing wireless multiple access access junction network, as shown in Figure 1.It is by a source node, a via node and a destination node composition.When its source node communicates with destination node under the help of via node, need two time slots, namely source node takies a time slot to via node and destination node broadcast data, and via node takies a time slot, helps source node to forward the data to destination node.

In order to improve the frame error rate performance of destination node while improving relay forwarding efficiency, scholar proposes and adopts distributed mode, to take into full account that the Turbo code of Shannon channel coding theorem assumed condition applies in the model of multiple access access, thus achieve certain performance gain.

But along with the new development that the communication technology is maked rapid progress, Turbo code error floor is higher, and its frame error rate target only has 10 ^-2to 10 ^-5, can not meet people far away to application needs 10 such as video conferences ^-8lower target requirement.Be subject to the limitation of performance during Turbo code high s/n ratio, Distributed T urbo code is difficult to obtain gratifying frame error rate performance in relay transmission.

Therefore, in existing multiple access access relay system, how utilizing the 3-DTurbo code solving Turbo code error floor lower to design a kind of relay transmission method, is the problem needing at present to solve.

Summary of the invention

Object of the present invention, for above-mentioned the deficiencies in the prior art, proposes a kind of relay transmission method based on distributed 3-DTurbo code, to improve the frame error rate performance of destination.

Technical thought of the present invention is, utilize excellent properties and the relaying technique of 3-DTurbo code, adopt traditional Turbo code to encode at source node, carry out selection check bit carry out third dimension coding at via node infiltration coefficient, destination node adopts the decoding of associating 3-DTurbo code.

Method of the present invention is achieved in that

(1) source node broadcast data step:

Source node S carries out Turbo code coding to oneself original information, obtains coded sequence c=(u, p ₁, p ₂), and coded sequence is modulated, obtain modulation sequence x; Source node S broadcast modulation sequence x is to via node R and destination node D;

(2) relay forwarding step:

(2.1) via node R carries out Turbo code decoding to the information of the source node S received, and obtains the estimated information of the raw information of source node S

(2.2) via node R is to the estimated information of source node S carry out Turbo code coding, obtain the verification sequence that two length is identical with information sequence

(2.3) via node R with infiltration coefficient λ (0≤λ≤1) to two verification sequence with select respectively, obtain verification sequence p to be encoded _{1 λ}and p _{2 λ}, then merge verification sequence p by the method alternately merged _{1 λ}and p _{2 λ}, obtain third dimension sequence u to be encoded _{λ p};

(2.4) via node R is by sequence u to be encoded for the third dimension _{λ p}send into third dimension encoder after interweaving, obtain verification sequence p _r, via node R is again to this verification sequence p _rmodulate, obtain modulation sequence x _r, and send it to destination node;

(3) destination node decoding procedure:

(3.1) destination node is to the source node signal y received _sdwith the signal y of relay forwarding _rdcarry out soft demodulation respectively, obtain c=(u, p ₁, p ₂) and p _rlog-likelihood ratio sequences corresponding respectively with wherein, L _uthe log-likelihood of corresponding is source information sequence u, that corresponding is source verification sequence p ₁log-likelihood, that corresponding is source verification sequence p ₂log-likelihood, third dimension verification sequence p _rlog-likelihood.

(3.2) the log-likelihood information that will obtain of destination node D send into third dimension decoder, decoding obtains external information L ^e, external information L ^ethrough deinterleaving, and two isometric components are divided into verify external information by deserializer with

(3.3) the destination node D method of infiltration coefficient adverse selection, by two component check information sequence p from source node ₁and p ₂corresponding likelihood ratio sequence with the component translated with third dimension decoder respectively verifies external information with merge, obtain revised two component check information sequence p ₁and p ₂log-likelihood ratio sequences with

(3.4) destination node D is by revised log-likelihood ratio sequences with and L _usend into Turbo code decoder and carry out decoding, translated the external information of information sequence by this decoder with carry out inner iterative, and upgrade two component check information sequence p ₁and p ₂the external information of component code verification sequence with

(3.5) destination node D is to the external information of the component code verification sequence that Turbo decoder translates with carry out infiltration coefficient selection respectively, obtain new component code check information sequence with

(3.6) destination node D likelihood ratio sequence that new component code check information sequence pair is answered with interweave after alternately merging, obtain third dimension coded sequence u _{λ p}corresponding likelihood ratio sequence again by this likelihood ratio sequence send into third dimension decoder, as the prior information of this third dimension decoder;

(3.7) destination node D carry out 16 take turns iterative decoding after, by Turbo code decoder export decode results.

The present invention compared with prior art tool has the following advantages:

1) existing Distributed T urbo code have employed convolution code at source node, coding gain is low, via node correct decoding and cooperation forward probability low, the present invention have employed Turbo code coding at source node, improve the correct decoding probability of via node R, reduce the probability of error propagation, be conducive to destination node and obtain diversity gain.

2) the present invention is by adjusting the size of infiltration coefficient, adjusts the forwarding data amount of via node, achieves the effectively compromise of relay forwarding efficiency and systematic function.

Accompanying drawing explanation

Fig. 1 is existing wireless multiple access access junction network model;

Fig. 2 is general flow chart of the present invention;

Fig. 3 is system general diagram of the present invention;

Fig. 4 is that the source node in the present invention is encoded sub-block diagram;

Fig. 5 is the via node compiling numeral block diagram in the present invention;

Fig. 6 is the sub-block diagram of destination node decoding in the present invention;

Fig. 7 is fixed relay position in the present invention, the destination node decoding performance analogous diagram that non-relay direct link transmission, the transmission of Distributed T urbo code and distributed 3-DTurbo code transmit;

Fig. 8 is the infiltration coefficient fixing 3-DTurbo code in the present invention, the destination node decoding performance analogous diagram that intermediate position is different;

Fig. 9 is fixed relay position in the present invention, the performance simulation figure of the destination node decoding of the distributed 3-DTurbo code of different infiltration coefficient.

Embodiment

With reference to Fig. 2 and Fig. 3, implementation step of the present invention is as follows:

Step 1, source node broadcast data

(1.1) source node S carries out Turbo code coded modulation to the initial data u of oneself:

With reference to Fig. 4, the realization of this step is as follows:

(1.1a) initial data u(length is K by source node S) carry out Turbo code coding, obtain coded sequence c=(u, p ₁, p ₂) (length is N=3K), wherein u is the information sequence of source node S coded sequence c, p ₁(length is K) is the verification sequence of first component code of source node S coded sequence c, p ₂(length is K) is the verification sequence of second component code of source node S coded sequence c; The Turbo coding method that source node uses can be chosen any one kind of them from existing method, see: ShuLin, DanielJ.Costello, Jr., " error control coding ", China Machine Press, 2007;

(1.1b) source node S carries out BPSK modulation to coded sequence c, obtains modulation sequence x;

(1.2) source node S is to via node R and destination node D broadcast modulation sequence x, and the signal that via node R and destination node D receives is expressed as:

$y_{\mathrm{sr}}=\sqrt{P_{\mathrm{sr}}}{h}_{\mathrm{sr}}x+n_{\mathrm{sr}}---1)$

$y_{\mathrm{sd}}=\sqrt{P_{\mathrm{sd}}}{h}_{\mathrm{sd}}x+n_{\mathrm{sd}}---2)$

Y in formula _srthe signal of the source node transmission that via node receives, y _sdthe signal of the source node transmission that destination node receives, P _srand P _sdbe respectively the received power of relaying and destination node, h _srfor source node is to the channel fading coefficient of via node, h _sdfor source node is to the channel fading coefficient of destination node, n _srfor source node is to the multiple Gaussian noise of via node, n _sdit is the multiple Gaussian noise that source node arrives destination node.

Step 2, relay forwarding data

With reference to Fig. 5, the compiling forwarding step of via node is as follows:

(2.1) via node R is to the information y receiving source node S _srcarry out Turbo code decoding, obtain the estimated information of source node primary data information (pdi) u (length is K); Turbo interpretation method can be chosen any one kind of them from existing method, see: ShuLin, DanielJ.Costello, Jr., " error control coding ", China Machine Press, 2007;

(2.2) via node R is to the estimated information of source node S carry out Turbo code coding, obtain the verification sequence of information sequence (length is N '=2K); Wherein, the coding method that via node uses uses coding method identical with source node, (length is K) is the estimated information verification sequence of source node the verification sequence of first component code, (length is K) is the estimated information verification sequence of source node the verification sequence of second component code;

(2.3) via node R with infiltration coefficient λ respectively to two verification sequence with select:

(2.3a) respectively by two verification sequence with be divided in turn and comprise the little verification sequence block of individual bit; Suppose λ=1/4, the length of verification sequence is K, then by two verification sequence with be divided into K/4 the little sequence blocks comprising 4 bits;

(2.3b) from verification sequence with each little sequence blocks same position on, select bit to export, and the bit of output arranged in turn, obtain verification sequence to be encoded with

Suppose infiltration coefficient λ=1/4 selected, verification sequence length is 16, then 16/4=4 can be divided into comprise 4 little verification sequence blocks, such as (1100), (0100) (0101), (1110) can be divided in turn, select first bit of each little sequence to export, the verification sequence to be encoded obtained

(2.4) by sequence to be encoded with merge by the method alternately merged, obtain third dimension sequence u to be encoded _{λ p};

(2.5) via node R is by sequence u to be encoded for the third dimension _{λ p}after quadratic polynomial interleaver QPP (QuadraticPermutationPolynomial) interweaves, send into third dimension encoder, obtain verification sequence p _λ, then via node is to verification sequence p _λcarry out BPSK modulation, obtain modulation sequence x _λ;

(2.6) via node R is by modulation sequence x _λbe sent to destination node, the signal indication that destination node D receives via node R is:

$y_{\mathrm{rd}}=\sqrt{P_{\mathrm{rd}}}{h}_{\mathrm{rd}}{x}_{\mathrm{\λ}}+n_{\mathrm{rd}}---3)$

Y in formula _rdthe information of the via node transmission that destination node receives, x _λthe signal that relaying sends, p _rdthe received power of destination node, h _rdthe channel fading coefficient that via node arrives destination node, n _rdit is the multiple Gaussian noise that via node arrives destination node.

Step 3, destination node decoding

With reference to Fig. 6, being implemented as follows of this step:

(3.1) destination node is to the source node signal y received _sdwith the signal y of relay forwarding _rdcarry out soft demodulation respectively, obtain c=(u, p ₁, p ₂) and p _rlog-likelihood ratio sequences corresponding respectively with wherein, L _uthe log-likelihood of corresponding is source information sequence u, that corresponding is source verification sequence p ₁log-likelihood, that corresponding is source verification sequence p ₂log-likelihood, that corresponding is third dimension verification sequence p _rlog-likelihood;

(3.2) the log-likelihood information that will obtain of destination node D send into third dimension decoder, decoding obtains external information L ^e, external information L ^ethrough deinterleaving, and two isometric components are divided into verify external information by deserializer with

(3.3a) in component verification external information with each information bit after add individual zero, obtain new verification external information with

(3.3b) by two component check informations from source node with by corresponding position and new verification external information with merge, obtain revised two component check information sequence p ₁and p ₂log-likelihood ratio sequences with

Suppose infiltration coefficient λ=1/4, the component check information of source node l _iit is component check information sequence in the i-th log-likelihood, wherein i ∈ 1,2 ..., K}, K are the length of code word, component external information w _jit is component external information sequence in a jth log-likelihood, wherein: j ∈ 1,2 ..., λ K}, obtains new verification external information by step (3.2a):

${L_{P_{1\mathrm{\λ}}}^e}^{\′}=(w_1,\mathrm{0,0,0},w_2,\mathrm{0,0,0}\·\·\·w_{\mathrm{\λK}},\mathrm{0,0,0});$

Component check information is merged by corresponding position by step (3.2b) with new verification external information obtain two dimensional component check information:

$L_{p_1}^{\′}=(l_1+w_1,l_2,l_3,l_4,l_5+w_2\·\·\·l_{K-3}+w_{\mathrm{\λK}},l_{K-2},l_{K-1},l_K).$

(3.4) destination node D is by revised log-likelihood ratio sequences with and Lu feeding Turbo code decoder carries out decoding, is translated the external information of information sequence, and upgrade two component check information sequence p by this decoder ₁and p ₂the external information of component code verification sequence with

(3.5a) destination node D is respectively by the external information of component code verification sequence with be divided into and comprise the little verification sequence block of individual bit; Suppose λ=1/4, the length of verification sequence is K, then by two verification sequence with be divided into K/4 the little sequence blocks comprising 4 bits;

(3.5b) destination node D is from verification sequence with each little sequence blocks same position on, select bit to export, and the bit of output arranged in turn, obtain verification sequence to be encoded with

(3.6) destination node D likelihood ratio sequence that new component code check information sequence pair is answered with interweave after alternately merging, obtain third dimension coded sequence u _{λ p}corresponding likelihood ratio sequence again by this likelihood ratio sequence send into third dimension decoder, as the prior information of this third dimension decoder;

(3.7) destination node D carry out 16 take turns iterative decoding after, by Turbo code decoder export decode results.

Effect of the present invention can be further illustrated by following emulation:

1. simulated conditions

If the message length of user is 1024, the Turbo code standard criterion in LTE selected by source node encoder, the Turbo code sequence of the code check of generation 1/3 deleted remaining to 1/2 code check.The third dimension encoder at via node place adopts code check to be 1, generator matrix g (D)=1/ (1+D ²) encoder.Suppose that the transmitted power of each node is all identical, all channels all obey the decline of Rayleigh block, adopt path loss model and $y_{d,i}=\frac{h_{d,i}}{\sqrt{d_{d,i}^n}}\·x_i+n_{d.i},i\∈\{s,r\},$ Suppose that path-loss factor is n=3.52.

2. emulate content

Emulation 1, when fixed relay station position be source node arrive the mid point of destination node time, the destination node decoding performance that the distributed 3-DTurbo code being 1/2 for non-relay direct link transmission, the transmission of Distributed T urbo code and infiltration coefficient respectively transmits emulates, the result of emulation as shown in Figure 7, abscissa in Fig. 7 represents that source node arrives the signal to noise ratio of destination node, ordinate represents the frame error rate of destination node decoding, and the meaning that in Fig. 7, each curve represents is as follows:

" non-relay " represents under the condition not having via node to forward, direct link transmission method;

" Distributed T urbo code " represents the transmission method using Distributed T urbo code;

" distributed 3-DTurbo " represents the transmission method using distributed 3-DTurbo code

As seen from Figure 7, the non-relay node-node transmission of via node transfer ratio is had to have very large performance gain; During low signal-to-noise ratio, the transmission of the transfer ratio tradition Turbo code of distributed 3-DTurbo code has the performance gain close to 2dB.

Emulation 2, when the infiltration coefficient of fixing 3-DTurbo code is 1/2, performance respectively for the different destination node decoding in via node position emulates, the result of emulation as shown in Figure 8, abscissa in Fig. 8 represents that source node arrives the signal to noise ratio of destination node, ordinate represents the frame error rate of destination node decoding, and the meaning that in Fig. 8, each curve represents is as follows:

" sr=1/2sd " represents that via node is positioned at the mid point of source node to destination node;

" sr=1/4sd " represents that via node is positioned at 1/4 place of source node to destination node;

Suppose to use represent as infiltration coefficient λ, when the distance of via node and source node is the α times of destination node and source node distance, the decoding performance of destination node.As seen from Figure 8, when infiltration coefficient is identical, during low signal-to-noise ratio, be better than during high s/n ratio, with compare, have larger performance gain; This is because when signal to noise ratio increases gradually, the probability that via node decoding is correct will significantly increase, and meanwhile, via node is relative better again with the channel of destination node, and the performance of destination decoding will be promoted significantly.

Emulation 3, when fixed relay station position be source node arrive the mid point of destination node time, destination node decoding performance respectively for the distributed 3-DTurbo code of different infiltration coefficient emulates, the result of emulation as shown in Figure 9, abscissa in Fig. 9 represents that source node arrives the signal to noise ratio of destination node, ordinate represents the frame error rate of destination node decoding, and the meaning that in Fig. 9, each curve represents is as follows:

" λ=1/2 " represent infiltration coefficient time 1/2 distributed 3-DTurbo code;

" λ=1 " represents that infiltration coefficient is the distributed 3-DTurbo code of 1;

As seen from Figure 9, when infiltration coefficient is larger, destination node decoding can obtain significant performance gain.

Although transmission rate reduces, the complexity of relaying adds, and performance obtains huge lifting.

Comprehensive analysis can obtain: 3-DTurbo code of the present invention has good performance gain than distributed Turbo code; When fixing infiltration coefficient and intermediate position respectively, distributed 3-DTurbo code can obtain different performance gains.Therefore, can by adjusting the position of via node and changing infiltration coefficient and reach the effectively compromise of via node complexity and destination node decoding performance.

Claims (4)

1., based on a relay transmission method for 3-DTurbo code, comprising:

(1) source node broadcast data step:

Source node S carries out Turbo code coding to oneself original information u, obtains coded sequence c=(u, p ₁, p ₂), and coded sequence is modulated, obtain modulation sequence x; Source node S broadcast modulation sequence x is to via node R and destination node D, wherein p ₁the verification sequence of first component code of source node S coded sequence c, p ₂it is the verification sequence of second component code of source node S coded sequence c;

(2) relay forwarding step:

(2.1) via node R carries out Turbo code decoding to the information of the source node S received, and obtains the estimated information of the raw information of source node S and only have when relaying correct decoding time, namely time, relaying just forwards;

(2.2) via node R is to the estimated information of source node S carry out Turbo code coding, obtain two length and estimated information identical verification sequence

(2.3) via node R with infiltration coefficient λ to two verification sequence with select respectively, obtain verification sequence p to be encoded _{1 λ}and p _{2 λ}, 0< λ≤1, is implemented as follows:

(2.3a) respectively by two verification sequence with be divided in turn and comprise the little verification sequence block of individual bit;

(2.3b) from verification sequence with on each little sequence blocks same position, select a bit to export, and the bit of output is arranged in turn, obtain verification sequence p to be encoded _{1 λ}and p _{2 λ};

Verification sequence p to be encoded is merged again by the method alternately merged _{1 λ}and p _{2 λ}, obtain third dimension sequence u to be encoded _{λ p};

(2.4) via node R is by sequence u to be encoded for the third dimension _{λ p}send into third dimension encoder after interweaving, obtain verification sequence p _r, via node R is again to this verification sequence p _rmodulate, obtain modulation sequence x _r, and send it to destination node;

(3) destination node decoding

(3.1) destination node D is to the source node signal y received _sdwith the signal y of relay forwarding _rdcarry out soft demodulation respectively, obtain c=(u, p ₁, p ₂) and p _rlog-likelihood ratio sequences corresponding respectively with wherein, L _uthe log-likelihood of corresponding is source information sequence u, that corresponding is source verification sequence p ₁log-likelihood, that corresponding is source verification sequence p ₂log-likelihood, third dimension verification sequence p _rlog-likelihood;

(3.2) the log-likelihood information that will obtain of destination node D send into third dimension decoder, decoding obtains external information L ^e, external information L ^ethrough deinterleaving, and two isometric components are divided into verify external information by deserializer with

(3.3) the destination node D method of infiltration coefficient adverse selection, by two source verification sequence p from source node ₁and p ₂corresponding likelihood ratio sequence with the component translated with third dimension decoder respectively verifies external information with merge, obtain revised two source verification sequence p ₁and p ₂log-likelihood ratio sequences with be implemented as follows:

First in component verification external information with each information bit after add individual zero, obtain new verification external information with

Again by two source verification sequence p from source node ₁and p ₂log-likelihood ratio sequences with by corresponding position and new verification external information with merge, obtain revised two source verification sequence p ₁and p ₂log-likelihood ratio sequences with

(3.4) destination node D is by revised log-likelihood ratio sequences with and L _usend into Turbo code decoder and carry out decoding, translated the external information of revised log-likelihood ratio sequences by this decoder with carry out inner iterative, and upgrade two source verification sequence p ₁and p ₂the external information of component code verification sequence with

(3.5) destination node D is to the external information of the component code verification sequence that Turbo decoder translates with carry out infiltration coefficient selection respectively, obtain new component code check information sequence with

(3.6) destination node D is by new component code check information sequence with corresponding likelihood ratio sequence interweaves after alternately merging, and obtains third dimension coded sequence u _{λ p}corresponding likelihood ratio sequence again by this likelihood ratio sequence send into third dimension decoder, as the prior information of this third dimension decoder;

(3.7) destination node D carry out 16 take turns iterative decoding after, by Turbo code decoder export decode results.

2. the relay transmission method based on 3-DTurbo code according to claim 1, the modulation system that wherein said step (1) and step (2.4) adopt, be binary phase shift keying BPSK, obtain modulation sequence by following corresponding formula:

x＝2c-1

x _R＝2p _R-1

Wherein, coded sequence c=(c ₁, c ₂..., c _n), N is code word size, x=(x ₁, x ₂..., x _n) be the modulation sequence that coded sequence c obtains after BPSK modulation; Modulation sequence x _r=(x _r1, x _r2..., x _{r λ N}) be code word p _r=(p _r1, p _r2..., p _{r λ N}) verification sequence that obtains after BPSK modulation.

3., according to the relay transmission method based on 3-DTurbo code described in claim 1, the destination node D wherein described in step (3.5) is to the external information of the component code verification sequence that Turbo decoder translates with carry out infiltration coefficient selection respectively, obtain new component code check information sequence with carry out as follows:

(3.5a) respectively by the external information of component code verification sequence with be divided into and comprise the little verification sequence block of individual bit;

(3.5b) from the external information verification sequence of two component code verification sequence with each little sequence blocks same position on, select bit to export, and the bit of output arranged in turn, obtain new component code check information sequence with

4. according to the relay transmission method based on 3-DTurbo code described in claim 1, intertexture in wherein said step (2.4) and step (3.6), all adopts quadratic polynomial interleaver QPP (QuadraticPermutationPolynomial) code word of former sequence to be rearranged.