KR20180078537A - Packet transmission method of relay node through network coding, relay apparatus transmitting packet through network coding, packet reception method of destination node and apparatus receiving network coded packet - Google Patents

Abstract

According to one aspect of the present invention, disclosed is a method for transmitting a packet through network coding in a relay node. The method of the present invention comprises the steps of: receiving a first packet encoded by channel coding including Luby transform (LT) encoding and low-density parity check (LDPC) encoding from a plurality of source nodes; generating a second packet by performing network coding using an LT matrix on the received first packet; and transmitting the generated second packet to a destination node.

Description

TECHNICAL FIELD [0001] The present invention relates to a packet transmission method using network coding in a relay node, a relay apparatus for transmitting a packet through network coding, a packet receiving method for a destination node, and a device for receiving a network coded packet APPARATUS TRANSMITTING PACKET THROUGH NETWORK CODING, PACKET RECEPTION METHOD OF DESTINATION NODE AND APPARATUS RECEIVING NETWORK CODED PACKET}

The present invention relates to a network coding method, and more particularly, to a method of network coding in a relay in an environment in which a packet is received from a plurality of source nodes and transmitted to a destination node.

A technique for transmitting data in existing mobile communication networks can be divided into a method of improving end-to-end transmission efficiency using channel coding and a method of increasing transmission efficiency by increasing the number of redundant data using network coding. The RaptorQ method has the maximum performance and the video transmission using the channel coding is used as a representative example. However, the RatorQ scheme has a drawback that it is vulnerable to changes in the channel environment due to an end-to-end channel coding scheme. The network coding scheme is used for the purpose of reducing the number of data transmissions. However, the network coding scheme is used for generating a large number of extra data packets and increasing the decoding probability at the receiving end. However, existing network coding is incompatible with RaptorQ channel coding, which makes it difficult to use.

According to an aspect of the present invention, there is provided a relay capable of concurrently performing channel coding and network coding in a mobile communication network environment, thereby increasing a data transmission success rate in an environment with a poor radio channel environment And to provide a packet transmission method through network coding at a relay node.

According to an aspect of the present invention, there is provided a method of transmitting a packet through network coding in a relay node, the method comprising: receiving a channel including a Luby transform (LT) encoding and a Low Density Parity Check (LDPC) Comprising the steps of: receiving a first packet encoded with a codeword, performing a network coding using an LT matrix on the received first packet to generate a second packet, and transmitting the generated second packet to a destination node And transmitting the data.

The relay node may perform network coding using the LT matrix using the maximum available bandwidth of the destination node at the relay node.

The LT matrix has a size of (n _{1R -} n _2R ) XN _m , n _1R denotes the number of channel coded packets transmitted from the first source node to the relay node, and n _2R denotes the second Means a number of channel coded packets transmitted from a source node to the relay node, and N _m may mean a maximum number of transmissions in the destination node in the relay node.

The second packet may be generated by arbitrarily selecting a combination between d first packets received from the first and second source nodes based on Robust Soliton Distribution (RSD).

을 고려하여 생성되되, Ω(x)는 d개의 제 1 패킷들을 선택하는 확률을 의미하고, n_1R은 제 1 소스 노드에서 상기 릴레이 노드로 전송되는 채널코딩된 패킷의 수를 의미하고, n_2R은 제 2 소스 노드에서 상기 릴레이 노드로 전송되는 채널코딩된 패킷의 수를 의미할 수 있다.The second packet

(X) denotes a probability of selecting d first packets, n _1R denotes the number of channel coded packets transmitted from the first source node to the relay node, and n _2R May refer to the number of channel coded packets transmitted from the second source node to the relay node.

According to another aspect of the present invention, there is provided a relay apparatus for performing packet transmission through network coding, the apparatus comprising: a channel coding unit for performing LU (Luby transform) encoding and LDPC (Low Density Parity Check) A network coding unit for performing a network coding using an LT matrix on the received first packet to generate a second packet, and a transmission unit for transmitting the generated second packet to a destination node And a transmission unit for transmitting the data to the mobile station.

According to another aspect of the present invention, there is provided a method of receiving a packet at a destination node, the method comprising: performing channel coding including an LT (Luby transform) encoding and an LDPC (Low Density Parity Check) Receiving a first packet from a plurality of source nodes, performing network coding using at least a portion of the first packets using an LT matrix to receive an encoded second packet from a relay node, And LT decoding the received first packet and the received second packet using a BP (Belief-Propagation) algorithm.

The packet receiving method further includes restoring information packets provided by the plurality of source nodes by performing in-activation decoding by providing packets restored through LT decoding as input to an inactivation decoding algorithm can do.

Wherein the LT decoding of the received first packet and the received second packet using the BP algorithm comprises LT decoding the received first packet and the received second packet and transmitting the lost first packet and the received second packet, And recovering the packet additionally.

According to another aspect of the present invention, there is provided an apparatus for receiving a network coded packet, the apparatus comprising: a channel coding unit configured to perform channel coding including an LBy transform (LT) encoding and an LDPC (Low Density Parity Check) A receiving unit that receives an encoded first packet from a plurality of source nodes and performs network coding using at least a part of the first packets using an LT matrix to receive an encoded second packet from a relay node; And a decoding unit LT decoding the received first packet and the received second packet using a BP algorithm.

According to the packet transmission method through network coding in the relay node of the present invention, when data is transmitted from a multi-source node to a specific destination node, transmission efficiency can be increased and efficiency of a mobile communication network can be maximized, There is a good effect on transmission.

1 is a conceptual diagram illustrating a system to which a packet transmission method based on network coding in a relay node is applied according to an embodiment of the present invention;
2 is a flowchart schematically illustrating a packet transmission method through network coding in a relay node according to an embodiment of the present invention;
3 is a flowchart schematically illustrating a method of receiving a packet at a destination node according to an embodiment of the present invention.
4 is a block diagram schematically illustrating a relay apparatus for performing packet transmission through network coding according to an embodiment of the present invention.
5 is a block diagram schematically illustrating a receiving apparatus for receiving a packet according to an embodiment of the present invention.
FIG. 6 is a graph comparing decoding success probabilities obtained by decoding a packet received at a source node 1, a source node 2, and a relay node at a destination node according to a method of receiving a packet at a destination node, according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a conceptual diagram illustrating a system to which a packet transmission method through network coding in a relay node is applied according to an embodiment of the present invention. 1, a combined network-channel coding system according to an embodiment of the present invention includes a source node S ₁ 110-1, a source node S ₂ 110-2, a relay R 120, Node < RTI ID = 0.0 > D 130 < / RTI >

Referring to FIG. 1, the source nodes 110-1 and 110-2, the relay node 120, and the destination node 130 may be base stations or terminals that communicate through a wireless network. A base station generally refers to a fixed point in communication with a terminal and includes a base station, a Node-B, an eNode-B, an advanced base station (ABS) But is not limited to, an HR-BS, a site controller, a base transceiver system (BTS), an access point (AP), or any other type of interfacing device capable of operating in a wireless environment.

The terminal may be a mobile station (MS), a user equipment (UE), a user terminal (UT), a wireless terminal, an access terminal (AT), a terminal, a fixed or mobile subscriber unit, A cellular phone, a wireless device, a wireless communication device, a wireless transmit / receive unit (WTRU), a mobile node, a mobile, a mobile station, a personal digital assistant ), A smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a consumer electronics (CE) or other terminology. Various embodiments of the terminal may be used in various applications such as cellular telephones, smart phones with wireless communication capabilities, personal digital assistants (PDAs) with wireless communication capabilities, wireless modems, portable computers with wireless communication capabilities, Devices, gaming devices with wireless communication capabilities, music storage and playback appliances with wireless communication capabilities, Internet appliances capable of wireless Internet access and browsing, as well as portable units or terminals incorporating combinations of such functions However, the present invention is not limited thereto.

According to an embodiment of the present invention, an encoding end that encodes data to transmit a packet includes source nodes 110-1 and 110-2 and a relay node 120, and a decoding end includes a destination node 130 do. In addition, in an embodiment where a plurality of source nodes 110-1 and 110-2 transmit packets toward one destination node 130, one or more relay nodes 120 may be connected to a source node Receives at least a part of the packets from the nodes 110-1 and 110-2, performs network coding, and relays the packets to the destination node 130. [

The source nodes 110-1 and 110-2 channel-code data to be transmitted, that is, information packets, and generate channel-coded packets to be transmitted to the relay node 120 or the destination node 130. [ The source nodes 110-1 and 110-2 basically generate channel-coded packets through RaptorQ channel coding and transmit them to the relay node 120 or the destination node 130. [

Basically, RaptorQ channel coding has the following transmission success probability.

However, the RaptorQ channel coding performs encoding only at the source nodes 110-1 and 110-2, and performs decoding only while decoding at the destination node 130. [ If data having a large capacity is distributed over a plurality of sources, performance is increased when network coding is performed in the relay node 120. At this time, if the relay node 120 performs network coding to increase the decoding probability in the RaptorQ decoding process at the destination node 130, the overall data transmission success rate can be increased.

The RaptorQ encoded packets in the source nodes 110-1 and 110-2 can be expressed by the following equations.

[Equation 1]

Here, G _{LT, i} represents a matrix for a LT encoding (Luby transform), and A ^-1 is a matrix for LDPC (Low Density Parity Check). c _i denotes original data to be transmitted (represented by an information packet in FIG. 1).

The RaptorQ channel coding performed in the source nodes 110-1 and 110-2 is a mixed type channel coding that performs pre-encoding with LDPC coding and LT coding, It has good performance.

However, as shown in Fig. 1, in the source S ₁ (110-1), e ₁₁ , e ₁₂ , e ₁₃ , It is assumed that three channel coded packets are transmitted, and e ₂₁ , e ₂₂ , e ₂₃ three channel coded packets are transmitted in the source S ₂ 110 - ₂ . At this time, the source S ₁ A e _11, e a e _22, e _23, if the failed transmission, channel coding alone RaptorQ destination node 130 in transmission ₁₂ and the source S ₂ (110-2) from transmitting (110-1) It is impossible to restore the entire original data.

At this time, data can be restored at the destination node 130 by utilizing the network coding of the relay node according to the embodiment of the present invention.

The relay node 120 receives e ₁₁ , e ₁₃ , two channel coded packets from the source node 110-1 and receives e ₂₁ , e ₂₂ , two channel coded packets from the source node 110-2 E ₃₁ , e ₃₂ , and e ₃₃ , respectively. At this time, the relay node 120 receives the LT encoding based on the RaptorQ coding to be decoded compatible with the channel coded packets received from the source node 110-1 and 110-2 at the destination node 130 Lt; / RTI > network coding. In addition, at this time, the relay node 120 can perform network coding by adding extra data in consideration of a packet lost in a wireless channel environment.

When the relay node 120 further intermittently transmits a network coded packet, the destination node 130 adds the e ₁₃ , e ₂₁ packet received from the source nodes 110-1 and 110-2 to the relay node 120, (Belief-Propagation) decoding using the e ₃₁ and e ₃₃ transmitted from the node 120 (e ₃₂ is lost), thereby recovering the lost e ₁₁ and e ₂₂ channel coded packets. Then, it can inactivatively decode the recovered e ₁₁ and e ₂₂ and the received e ₁₃ and e ₂₁ to recover the original information packets. This result is possible because the relay node 120 transmits e ₃₁ and e ₃₃ by performing network coding based on LT encoding compatible with Raptor Q channel coding.

The network coding method at the relay node 120 and the joint coding decoding method at the destination node 130 will be described in more detail with reference to FIG. 2 to FIG.

2 is a flowchart schematically illustrating a packet transmission method through network coding in a relay node according to an embodiment of the present invention.

로 표현할 수 있다. Referring to FIG. 2, the relay node receives a packet from a source node (S210). Considering the loss rate ε _iR in the wireless network, the packet received from the source node 1 is n _1R = (1-ε _1R ) N ₁ and the packet received from the source node 2 is n _2R = (1-ε _2R ) ≪ / _RTI > Here, N ₁ denotes a packet transmitted from the source node 1, and N ₂ denotes a packet transmitted from the source node 2. To simplify this, packets received at the relay node

.

After receiving the packet, in order to utilize the maximum available bandwidth of the link from the relay node to the destination node, the received data is encoded with the _Nm network coded packet using the LT code (S220). This can be expressed by the following equation. Where N _m is the maximum number of packets transmitted on the link from the relay node to the destination node.

&Quot; (2) "

Where G _LTNC is the LT generation matrix of network coded packets of size (n _1R + n _2R ) x N _m . This network coded packet can be generated by arbitrarily selecting a combination between the packets coming in from the sources (Source 1 and Source 2) based on the following equation (RSD Reference: Robust Soliton Distribution).

&Quot; (3) "

Where n _1R denotes the number of channel coded packets transmitted from the first source node to the relay node, n _2R denotes the number of channel coded packets transmitted from the first source node to the relay node, Means the number of channel coded packets transmitted from the node to the relay node.

The relay node can generate the network coded packet from the destination node with the RaptorQ decoding enabled packet. Basically, LT coding is a kind of channel coding, but in the embodiment of the present invention, RaptorQ channel decoding is enabled at a destination node through a network coding scheme using LT coding matrix.

The relay node transmits the network coded packets generated through the process to the destination node (S230).

3 is a flowchart schematically illustrating a method of receiving a packet at a destination node according to an embodiment of the present invention.

Referring to FIG. 3, the destination node receives a channel coded packet from the source node 1 and the source node 2, and receives a network coded packet from the relay node (S310). At this time, the received packet can be expressed by the following equation.

&Quot; (4) "

은 소스1에서 손실 없이 정상적으로 받은 패킷이고,

은 소스2에서 손실 없이 정상적으로 받은 패킷이다.

은 중간노드에서 손실 없이 받은 LT 인코딩된(네트워크 코딩된) 패킷이다. here,

Is a packet normally received from source 1 without loss,

Is a packet normally received from source 2 without loss.

Is an LT encoded (network coded) packet received without loss at the intermediate node.

The destination node performs LT decoding through the BP algorithm, which is the first step of RaptorQ decoding (S320). RaptorQ decoding can be roughly divided into two parts, one is BP decoding and the other is in-activation decoding.

In decoding at the destination node, the decoding probability of RaptorQ depends on the number of channel coded packets at the destination node. Thus, it performs joint network-channel decoding to increase the probability of recovery of channel coded packets from the two source nodes.

과 중간노드로부터 받은 패킷

을 BP 알고리즘을 이용하여

으로 디코딩할 수 있다. 이때, l과 h는 중간노드로부터 추가적으로 복원한 패킷이다. 그리고는, 복원된 채널코딩된 패킷들을 인액티베이션(inactivation) 디코딩 알고리즘의 입력으로 넣어 인액티베이션 디코딩을 수행한다(S330). 인액티베이션 디코딩 수행 결과, 정보 패킷들을 복원할 수 있다. The destination node first receives the packet received from the source node 1, the source node 2

And the packet received from the intermediate node

Using the BP algorithm

Lt; / RTI > In this case, l and h are packets further restored from the intermediate node. Then, in-activation decoding is performed by inputting the reconstructed channel-coded packets as an input of an inactivation decoding algorithm (S330). As a result of the in-activation decoding, information packets can be recovered.

In the embodiment of FIG. 1, when the destination node 130 receives four packets of (e ₁₃ | e ₂₁ | e ₃₁ , e ₃₃ ), first, the BP algorithm is performed based on the four packets, And restores the two channel-coded packets. One is e ₁₁ transmitted from the source node 110 - ₁ , and the other is e ₂₂ transmitted from the source node 110 - 2. Then, based on the reconstructed four channel coded packets (e ₁₁ , e ₁₃ e ₂₁ , e ₂₂ ), activation decoding is performed to recover all the information packets.

As a result, the network-coded packet at the relay node can be decoded by the BP decoding method among the RaptorQ pre-decoding method at the destination node, which is utilized in RaptorQ channel decoding to generate the final decoded packet The data restoration rate at the final decoding stage can be increased.

4 is a block diagram schematically illustrating a relay apparatus for performing packet transmission through network coding according to an embodiment of the present invention. 4, the relay apparatus 400 according to an exemplary embodiment of the present invention may include a receiver 410, a network coding unit 420, and a transmitter 430. Referring to FIG.

The receiving unit 410 receives channel coded packets from the source node 1 and the source node 2.

The network coding unit 420 performs network coding using an LT matrix on the decoded packet to generate a network coded packet. At this time, the network coding unit 420 preferably performs network coding using the LT matrix using the maximum available bandwidth from the relay node to the destination node. At this time, the LT generation matrix used by the network coding unit 420 may have a size of (n _1R + n _2R ) x N _m .

According to an embodiment of the present invention, the network coding unit 420 may perform a network coded process by arbitrarily selecting a combination between packets incoming from sources (source 1 and source 2) based on Robust Soliton Distribution (RSD) And generates a packet.

In accordance with another embodiment of the invention, a network coding section 420 n _1R has a first number of channel-coded packet transmitted from the source node to the relay node and a channel to be transmitted from the second source node to the RS coding Based on the number of received packets, calculates the probability of selecting packets coming in from the d source nodes and performs network coding.

The transmitting unit 430 transmits the packets generated by the network coding unit 420 to the destination node.

5 is a block diagram schematically illustrating a receiving apparatus for receiving a packet according to an embodiment of the present invention. 5, a receiving apparatus 500 according to an embodiment of the present invention may include a receiving unit 510, a first decoding unit 520, and a second decoding unit 530.

5, the receiving unit 510 receives a transmission packet encoded by Raptor Q channel coding from a plurality of source nodes, and transmits an LT matrix to at least a part of transmission packets provided by a plurality of source nodes And receives encoded network coding packets from the relay node by network coding.

The first decoding unit 520 performs LT decoding using the BP algorithm based on the transmission packet and the network coding packet received from the receiver 510. [ LT decoding, it is possible to additionally recover the lost packet while reaching the receiving apparatus 500 in addition to the packet received by the receiving unit 510. [

The second decoding unit 530 performs in-activation decoding by providing the input of the inactivation decoding algorithm to the packets reconstructed through the LT decoding in the first decoding unit 520, It is possible to restore the provided information packet.

FIG. 6 is a graph comparing decoding success probabilities obtained by decoding a packet received at a source node 1, a source node 2, and a relay node at a destination node according to a method of receiving a packet at a destination node, according to an embodiment of the present invention.

Referring to FIG. 6, a result obtained by decoding a packet received at the source node 1, the source node 2, and the relay node at the destination node, respectively, can be confirmed. As a result of applying the joint coding method according to an embodiment of the present invention, it can be confirmed that the result is superior to the conventional RaptorQ encoding.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (10)

A method for packet transmission through network coding in a relay node,
Receiving a first packet encoded with channel coding including a Luby transform (LT) encoding and a Low Density Parity Check (LDPC) encoding from a plurality of source nodes;
Performing a network coding using an LT matrix on the received first packet to generate a second packet; And
And transmitting the generated second packet to a destination node. The method according to claim 1,
Wherein the relay node performs network coding using the LT matrix using the maximum available bandwidth of the destination node at the relay node. The method according to claim 1,
The LT matrix has a size of (n _{1R -} n _2R ) XN _m , n _1R denotes the number of channel coded packets transmitted from the first source node to the relay node, and n _2R denotes the second Coded packets transmitted from a source node to the relay node, and N _m denotes a maximum number of transmissions in the destination node in the relay node. The method according to claim 1,
Wherein the second packet is generated by randomly selecting a combination between d first packets received from the first and second source nodes based on Robust Soliton Distribution (RSD) Way. 5. The method of claim 4,
The second packet

(X) denotes a probability of selecting d first packets, n _1R denotes the number of channel coded packets transmitted from the first source node to the relay node, and n _2R Means a number of channel coded packets transmitted from the second source node to the relay node. A relay apparatus for packet transmission through network coding,
A receiver for receiving a first packet encoded with channel coding including a Luby transform (LT) encoding and a Low Density Parity Check (LDPC) encoding from a plurality of source nodes;
A network coding unit for performing a network coding using an LT matrix on the received first packet to generate a second packet; And
And a transmitter for transmitting the generated second packet to a destination node. A method for receiving a packet at a destination node,
Performing channel coding including an Luby transform (LT) encoding and a Low Density Parity Check (LDPC) encoding on an information packet to receive an encoded first packet from a plurality of source nodes;
Performing network coding using at least a portion of the first packet using an LT matrix to receive an encoded second packet from a relay node;
And LT decoding the received first packet and the received second packet using a BP (Belief-Propagation) algorithm. The method according to claim 1,
Further comprising restoring information packets provided by the plurality of source nodes by performing in-activation decoding by providing packets reconstructed through LT decoding as input to an inactivation decoding algorithm, Packet receiving method. 2. The method of claim 1, wherein LT decoding the received first packet and the received second packet using a BP algorithm comprises:
And LT decoding the received first packet and the received second packet to further recover lost packets while being transmitted to the destination node. An apparatus for receiving a network coded packet,
Performing channel coding including an Luby transform (LT) encoding and an LDPC (Low Density Parity Check) encoding for an information packet to receive an encoded first packet from a plurality of source nodes, and for at least a portion of the first packet A receiver for performing network coding using an LT matrix and receiving an encoded second packet from a relay node; And
And a decoding unit for LT decoding the received first packet and the received second packet using a BP algorithm.

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