CN101635606A - Wireless multi-hop cascade adaptive network coding cooperation method - Google Patents
Wireless multi-hop cascade adaptive network coding cooperation method Download PDFInfo
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- CN101635606A CN101635606A CN200810045620A CN200810045620A CN101635606A CN 101635606 A CN101635606 A CN 101635606A CN 200810045620 A CN200810045620 A CN 200810045620A CN 200810045620 A CN200810045620 A CN 200810045620A CN 101635606 A CN101635606 A CN 101635606A
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Abstract
The invention relates to a network coding method in a wireless multi-hop network, in particular to the adaptive network coding method matched with an instantaneous topological structure. The method can acquire higher coding gain and diversity gain through the match of a topological graph and a check matrix of an instant LDPC code by a belief propagation coding method for decoding. The method comprises the following steps of: firstly, introducing a concept and functions thereof of network coding; then providing an analysis method for a wireless relay network with the network coding technology, and a generation method for a coding check matrix; then providing a model of the wireless multi-hop network; providing a generation method for the coding check matrix aiming at the model; and finally, providing a specific example.
Description
Technical field
What the present invention relates to is a kind of network coding method in the wireless multi-hop network.Particularly based on the multihop network coding cooperative technology in the collaboration diversity wireless communication system of relaying.
Background technology
Network code is the combination of a kind of coordination technique and coding techniques, it is a kind of theory of cooperating with each other between the node emphasized, it is from the angle of network information opinion, the notion of this node cooperative coding is applied to whole communication network, to improve the overall performance of network.The thought of network code is: allow the simple code capacity at via node place, can promote network capacity like this.By theoretical research and The Realization of Simulation to network code, display network is coded in the advantage in the Network Transmission at present, and it not only can improve network traffics, also at aspects such as information reliability, fail safes great application is arranged.
Network code forwards after allowing the node in the network that the information that receives is encoded again, thereby improves the transmission performance of wireless network, is mainly used in the multicast scene.When one or several node simultaneously when several other nodes send data, often will be by the transmission of other nodes, network code allows via node that the information that receives is encoded, and a plurality of packets that will receive reconfigure according to certain special algorithm again and send.Network coding technique is seen Fig. 1 from cable network to the expansion of wireless multi-hop communication network.
Left figure arrow is represented oriented link among Fig. 1, and the capacity of supposing every link is 1, and node 1 sends b1 and two bit information of b2 to node 6 and 7 respectively, if adopt traditional communication mode, will produce queuing delay between intermediate node 4 and 5.And the simple code strategy shown in the employing figure can make bandwidth efficiency higher, transmit behind two bit XORs that node 4 will receive, receiving node 6 will receive b1 and
, decoding can recover b2, and in like manner node 7 also can be received complete information.
It is generalized in the wireless multi-hop communications field, shown in the right figure of Fig. 1, introduce the notion (the dotted line circle that with the node is the center is represented) of transmission radius, by the coding that carries out at node 4 and the decoding of two receiving nodes, when receiving complete information, improved efficiency of transmission.
In wireless network, adopt independent relaying antenna that user data is carried out relaying based on the cooperative diversity system of relaying, thereby obtain space diversity gain; The user collaborative diversity system be by user terminal mutually as relaying, thereby the diversity reception that realizes user terminal under the condition that does not increase equipment complexity and equipment amount obtains space diversity gain.Studies show that, network code is applied to all will produce good diversity performance based on the wireless system of relaying and the wireless network of user collaborative.Because the collaboration diversity based on relaying occurs in some wireless communication standards, and the easier and existing compatibility of communicating by letter, therefore have more using value, be research object with wireless cooperation diversity among the present invention, studied the network coding method of a kind of practicality in the multihop network based on relaying.So in the wireless multi-hop network model in the present invention, the mode of each grade all is made of source end, relaying antenna and destination.
Summary of the invention
The network code scheme can be divided into linear and non-linear two kinds, and wherein the Code And Decode of linear method is simple relatively, therefore, generally all tends to adopt linear method.In directed networks,, linear solution is arranged necessarily then if a network code problem is separated.Guaranteed the validity of linear algorithm theoretically.Linear combination requires network node to have higher computing capability, yet according to Moore's Law, along with the reduction of processing cost, the bottleneck of network required higher bandwidth support and the QoS of deflection service gradually guarantees.Linear network encoding is node to be transmitted the information linearity be mapped in the finite field, utilizes linear relationship to realize the coding and decoding process.Supposing that each information packet is long is L bit, when it with the data packet length that will make up not simultaneously, short information plus is outer a string 0, and the every s in the bag continuous bit formed F
2A symbol on the s territory then comprises L/s symbol in a bag.Under uniform enconding, utilization multiplication and add operation make the data that send from node receive the linear combination of information for this node.
For network coding technique is carried out deep theoretical research, it need be abstracted into valid model, utilize fundamental research encoded questions such as graph theory, matrix theory, information theory and carry out corresponding Performance Evaluation.The general Study thinking of network code is: at first the practical study topology of networks is abstracted into figure, obtains corresponding research conclusion from the graph theory angle; On the one hand it further is abstracted into algebraically then and realizes, carry out problem solving with more deep mathematical theory, carry out corresponding calculated machine analog simulation on the other hand, the results of property that obtains by emulation is assessed the performance of cordless communication network coding techniques.
1. the instant coupling of the topological diagram of coding Network Based and LDPC sign indicating number
Fig. 2 is a collaboration diversity wireless communication system model based on relaying, comprises the base station, relaying and terminal three parts.Discussed here be terminal as the source end, the situation of base station during as destination is promptly from the situation of terminal use when the base station sends data.The network topological diagram that forms when this data are transmitted in network can be regarded a kind of sparse graph sign indicating number as, just can in the base station user data be recovered according to the belief propagation decoding algorithm based on figure as long as known this topological diagram.Therefore the key of this network code is to set up the corresponding relation of topological diagram and sparse graph (or test matrix).
With collaboration diversity wireless system shown in Figure 2 is example, the structure of its check matrix H such as Fig. 3.This matrix is made of the Sparse Array P on the left side and the unit matrix I merging on the right.Line number among the P equals the relay point number; The columns of P equals the number of terminal.The capable j row of i are if 1 shows that the data of i relaying institute relaying comprise the data content of j terminal among the P.1 distribution is at random in every row of P.And 1 number of every row is a pre-set parameter D
1This sign indicating number based on figure can be complementary with the instant network topology, because the terminal number in the network is many, so each relaying can therefrom be selected suitable terminal data to carry out network code and carries out forward pass.Therefore the relation between the data that receive in some moment of base station can be represented with a LDPC sign indicating number, just the data of a plurality of user terminals can be recovered through the decoding of LDPC sign indicating number.This method to synchronous requirement a little less than, can link situation according to topology and set up yard figure row decoding of going forward side by side in real time, therefore be called adaptive network coding.
2. wireless multi-hop system model and cascade network coded diversity
Fig. 4 has provided the multi-hop cascade network model of a two-tier system.Ground floor is by K
2Individual bunch of composition contains K in every bunch
1Individual source end, R
1Individual relaying and a destination.The second layer is with the K in the ground floor
2Individual point of destination is as the source end, and contains R
2Individual relaying and a destination.
A bunch N of each bunch
A(destination) sets up (a K by the parity check bit that the relaying of uniting in all information bits and this bunch generates
1+ R
1, K
1) outer sign indicating number C
1If bunch header decode is correct, it will broadcast in addition sign indicating number to R
2Individual two layers of relaying and node N
RIf its cluster header decode failure at least, then corresponding outer sign indicating number can not forwarded to N
BAnd N
BThe place will be in the report of announcing the node decoder failure.In case all bunches header decode is correct, R
2In individual two layers of relaying each is stored the outer sign indicating number of all band noises that transmit from individual bunch of head in (a K
1+ R
1)
2* K
2Matrix in.Then, each row with matrix generates ISN C
2Check digit.Then, ISN will pass to destination N by relaying
BN
BUtilize C
1And C
2Decode.This model can expand to the cascade of n level.
The network code of this cascade can obtain higher diversity gain in wireless multi-hop network.But when adopting fixing ISN and outer yard, topology of networks is had relatively high expectations, for dynamic wireless network poor practicability.Therefore the invention provides the network coding method in a kind of adaptive multi-hop wireless network, provided the check matrix of the LDPC sign indicating number that matches.
3. the cascade adaptive network coding diversity that is complementary with wireless multi-hop network
The key of adaptive network coding is to set up the check matrix of the LDPC sign indicating number that is complementary with it.Fig. 5 is the basic structure of the check matrix of a n level network.Wherein, the structure of submatrix 1 is seen shown in Figure 6, wherein
The expression information bit,
The expression check digit.Each LDPC battle array of the left-hand component of submatrix 1 is R
1* K
1Matrix, the diagonal matrix of right-hand component is (a R
1* K
2) * (R
1* K
2) matrix.And Fig. 7 has provided the structure of submatrix 2: wherein the subdivision of odd indexed is by K
1* K
1Diagonal matrix and zero battle array constitute, and the subdivision of even number sequence number is by R
1* R
1Diagonal matrix and zero battle array constitute.The distribution situation of diagonal matrix is one to one in the subdivision of the subdivision of odd indexed and even number sequence number, and this is by the structure decision of outer sign indicating number.The number of the diagonal matrix of each subdivision is a preset parameters D
2, and the diagonal matrix of each subdivision is a random distribution.The check digit information of certain relaying of per two row (sequence number is strange, even sequencing) expression second layer relayings of diagonal angle submatrix.
4. the decoding of cascade adaptive network coding
The check matrix that is complementary with cascade adaptive network coding is a kind of LDPC sign indicating number of low code check.Therefore can adopt the interpretation method commonly used of LDPC in the base station---belief propagation decoding.This method is a kind of approximate maximum-likelihood decoding, can obtain very high coding gain, and simultaneously because it can Parallel Implementation, so complexity is low, is the research focus in present signal processing field.
Description of drawings:
Fig. 1 is the expansion of network coding technique from the cable network to the wireless network.
Fig. 2 is the distributed wireless relay system of band network code.
Fig. 3 is the general expression of the check matrix of distributed wireless system.
Fig. 4 is the multi-hop cascade network model of a two-layer relaying framework.
Fig. 5 is the structure piecemeal of the check matrix of system shown in Figure 4.
Fig. 6 is that the check matrix of the ground floor relay system of system shown in Figure 4 is the structure of submatrix 1.
Fig. 7 is the structure chart of submatrix 2.
Fig. 8 is at K
1=4, R
1=2, K
2=4, R
2=2, D
1=D
2During=2 situation, an example of submatrix 1.
Fig. 9 is at K
1=4, R
1=2, K
2=4, R
2=2, D
1=D
2During=2 situation, an example of submatrix 2.
Figure 10 is at K
1=4, R
1=2, K
2=4, R
2=2, D
1=D
2During=2 situation, an example of system's corresponding check matrix.
Embodiment
At K
1=4, R
1=2, K
2=4, R
2=2, D
1=D
2During=2 situation, we realize check matrix.We according to signal from the source end to destination such time sequencing carry out.At first, we generate submatrix 1, and its left-half is to press diagonal by 42 * 4 LDPC matrix (1 number is 2 in every row) to arrange, and 8 * 16 the matrix that is constituted in other position zero paddings; Its right half part is one 8 * 8 a diagonal matrix.(see figure 8) then, we generate submatrix 2, sequence number is that the subdivision of odd number is made of diagonal matrix and 2 zero battle arrays of 24 * 4, they are random alignment; Sequence number is that the subdivision of even number is made of 22 * 2 diagonal matrix and 2 zero battle arrays, and they to have with sequence number be the corresponding random alignment of submatrix of the subdivision of odd number.Remaining part zero padding has just been obtained the left-hand component of matrix 2, the right merges one 12 * 12 diagonal matrix and just obtains matrix 2 then again.Several combinations that (see figure 9) will generate according to structure shown in Figure 6 have at last just obtained final 20 * 36 check matrix.(see figure 10)
Claims (9)
1. the present invention is applied to the wireless multi-hop cascade network, is a kind of adaptive network coding cooperation method, may further comprise the steps:
Step 1: the phase-split network structure provides network topological diagram according to network model;
Step 2: draw the network check matrix according to network topological diagram;
Step 3: decipher according to check matrix and the data of receiving in terminal.
2. wireless multi-hop cascade network as claimed in claim 1, be to constitute by wireless communication system based on the relaying cooperation, wireless communication system based on the relaying cooperation is made up of some sources end, some relayings, some destinations, and this technical scheme is the tool good application prospects in practical communication system.
3. as claimed in claim 1ly adopted an analytical method that obtains sign indicating number figure mapping according to net figure mapping, be about to network topological diagram and be mapped to geometric figure, obtained coding codeword according to this figure then in analyzing based on the wireless network of relaying cooperation.
4. the check matrix with the sign indicating number figure of the wireless network of cooperating based on relaying coupling is a kind of special expression-form, it adopts the design philosophy of LDPC sign indicating number, form by the sparse matrix on the left side and the diagonal matrix merging on the right, the row correspondence of left side sparse matrix the information of each source end, row corresponding each via node in the network.
5. in wireless multi-hop system, second level relaying place, the signal that via node is received is the outer sign indicating number that the information that transmits of bunch head of last layer and check information are formed, uniform enconding becomes ISN to be sent to destination then.
6. the novel structure at the given check matrix of wireless multi-hop cascade network of the present invention according to claim 1, directly perceived, decoding is simple, and diversity gain is big, and it is made of submatrix 1, submatrix 2 and full null part.
7. the left-hand component of submatrix 1 as claimed in claim 6 is pressed the diagonal arrangement by low-density checksum (LDPC) numeral battle array and is formed, and right-hand component is a diagonal matrix.
8. submatrix as claimed in claim 62 left sides are made of the subdivision of odd indexed and the subdivision of even number sequence number, the right is a diagonal matrix, wherein each subdivision on the left side is made of diagonal matrix and zero battle array, the distribution situation of diagonal matrix is one to one in the subdivision of the subdivision of odd indexed and even number sequence number, this is by the structure decision of outer sign indicating number, the number of the diagonal matrix of each subdivision is a preset parameters D2, and the diagonal matrix of each subdivision is a random distribution.
9. interpretation method as claimed in claim 1 is the interpretation method commonly used of LDPC---belief propagation decoding, this method is a kind of approximate maximum-likelihood decoding, can obtain very high coding gain, and it can Parallel Implementation, complexity is low, is the research focus in present signal processing field.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102332964A (en) * | 2010-07-12 | 2012-01-25 | 电子科技大学 | Multi-access relay cooperative communication technology based on network-channel combined codingdecoding |
| CN103378875A (en) * | 2012-04-25 | 2013-10-30 | 杭州讯能科技有限公司 | OFDM cooperative diversity transmission method and device |
| CN106255164A (en) * | 2015-06-11 | 2016-12-21 | 北京信威通信技术股份有限公司 | Collaboration communication processing method and processing device |
| CN110741573A (en) * | 2017-06-09 | 2020-01-31 | 区块链控股有限公司 | Method and system for selectively propagating transactions using network coding in a blockchain network |
-
2008
- 2008-07-23 CN CN200810045620A patent/CN101635606A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102332964A (en) * | 2010-07-12 | 2012-01-25 | 电子科技大学 | Multi-access relay cooperative communication technology based on network-channel combined codingdecoding |
| CN103378875A (en) * | 2012-04-25 | 2013-10-30 | 杭州讯能科技有限公司 | OFDM cooperative diversity transmission method and device |
| CN103378875B (en) * | 2012-04-25 | 2015-07-15 | 杭州讯能科技有限公司 | OFDM cooperative diversity transmission method and device |
| CN106255164A (en) * | 2015-06-11 | 2016-12-21 | 北京信威通信技术股份有限公司 | Collaboration communication processing method and processing device |
| CN110741573A (en) * | 2017-06-09 | 2020-01-31 | 区块链控股有限公司 | Method and system for selectively propagating transactions using network coding in a blockchain network |
| TWI812623B (en) * | 2017-06-09 | 2023-08-21 | 安地卡及巴布達商區塊鏈控股有限公司 | Node device, computer-implemented method, and related non-transitory processor-readable medium |
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Application publication date: 20100127 |