KR101465891B1 - Traffic redundancy elimination method and apparatus in wireless network - Google Patents

Abstract

A method and an apparatus for the elimination of traffic redundancy in a wireless network are disclosed. The method for the elimination of the traffic redundancy comprises the following steps: receiving a packet; analyzing the packet to find redundant chunks; if the redundant chunks exist, calculating a probability of overhearing of a target terminal using the redundant chunks and a channel state of the target terminal; eliminating the redundant chunks and encoding the packet according to the calculated probability of overhearing; and transmitting the encoded packet to the target terminal.

Description

[0001] The present invention relates to a traffic redundancy elimination method and apparatus in a wireless network,

The present invention relates to a method and apparatus for traffic deduplication in a wireless network capable of reducing redundant network traffic in a wireless network providing multiple rates.

With the development of devices such as smart phones and tablet PCs, mobile data traffic using these devices is also rapidly increasing. This increase in mobile data traffic can cause serious network load in a wireless network environment. Particularly, in a network structure in which one base station (or a repeater) manages a plurality of terminals, since a base station transmits data traffic to all terminals in its coverage, as the number of terminals and the data received from the terminals increases, Serious bottlenecks will occur. As a result, not only the time for transmitting data from the base station to the terminal is delayed but also the bandwidth for transmitting data to each terminal is also reduced, so that the terminals can not receive good quality services.

To solve this problem, there is a network-level redundancy elimination (RE) algorithm. The RE algorithm can effectively reduce redundant traffic from the viewpoint of the network layer, thereby reducing traffic inside the network.

In the case of an application-level web cache technique, duplicate content is discriminated on the basis of URL (uniform resource locator) or content name. Therefore, even if the content is the same, if the URL or name is different, Can not be reduced.

However, since the RE algorithm uses the actual byte stream of the contents, it is possible to discriminate the redundant traffic regardless of the type of the application. Also, in actuality, the network traffic may have partially the same byte sequence even if it is not the same content. The RE algorithm can effectively reduce the redundant network traffic by using a protocol independent method.

This conventional RE algorithm achieves a deduplication effect by performing encoding and decoding. Encoding refers to a process of reducing a packet to be sent by a transmitting side to a small size, and decoding refers to a process in which a receiving side restores an encoded packet to an original packet. To this end, the transmitting side and the receiving side have the same storage space structure. The cache table contains chunks and fingerprints, and the chunks are stored by performing the RE algorithm on the packets and have a smaller size than the packets. A fingerprint is a hash function value of a chunk that is smaller than a chunk and serves as metadata for the chunk. The transmitting side and the receiving side select a chunk in the packet and store it in the cache table together with the fingerprint. The chunk or fingerprint selection method can be variably applied according to various RE algorithms.

This conventional RE algorithm is designed to eliminate redundant traffic between two fixed servers in a wired network. That is, since the error rate of the packets transmitted between each other is very low and the communication is continuously performed, the cache table synchronization between the two fixed servers can be easily performed. However, in order to perform the RE algorithm in the wireless network in which the base station and the plurality of terminals exist, there is a lot of overhead to perform the cache table synchronization between the base station and the terminals, and since the terminals continuously move in the wireless network, It is practically impossible to maintain and manage cache table information in real time.

The present invention relates to a method and apparatus for deduplication in a wireless network capable of effectively eliminating traffic redundancy by judging whether redundant chunks are stochastically determined by using only a minimum amount of information necessary for calculating an overhearing probability of a terminal in a wireless network .

It is another object of the present invention to provide a traffic duplication elimination method and apparatus in a wireless network capable of effectively eliminating traffic duplication without a cache table synchronization between a wireless network and a terminal.

It is another object of the present invention to provide a method and apparatus for removing traffic redundancy in a wireless network having a small overhead by maintaining only minimum information necessary for calculating the overhearing probability of a terminal.

According to an aspect of the present invention, there is provided a wireless network capable of effectively eliminating traffic redundancy by judging whether there is a redundant chunk by using only a minimum amount of information necessary for calculating an overhearing probability of a terminal in a wireless network, A device for removal is provided.

According to an embodiment of the present invention, there is provided a communication system including: a communication unit for receiving a packet from a core network; And an encoding unit for encoding the packet by eliminating a redundant chunk of the packet according to overhearing of a target terminal considering a transmission mode of the packet, wherein the encoded packet is transmitted to the target terminal through the communication unit May be provided.

A searching unit for analyzing the packet and searching for the duplicated chunk; And a calculation unit for calculating an overhearing probability using the overlapping chunk information and the channel state of the target terminal if the search result of the search unit includes a duplicate chunk, wherein the encoding unit calculates the overlapping chunks according to the calculated overhearing probability, It can be determined whether or not to replace the previously stored fingerprint.

The searching unit may divide the packet into a predetermined chunk size to generate a fingerprint for each chunk, and search for the duplicated chunk by searching whether the generated fingerprint is stored.

Wherein the calculation unit applies the multiple bit rate model using the time difference between the overhearing time and the current time of the overlapping chunks and the transmission mode of the target terminal at the current time to determine a channel state of the target terminal at the overhearing time of the overlapping chunks And the overhearing probability of the target terminal can be calculated using the predicted channel state and the transmission mode of the redundant chunk.

The calculation unit may estimate a transmission mode according to a channel state of the target terminal at an overhearing time of the overlapping chunk by applying a rate adaptation algorithm.

The calculation unit may calculate the overhearing probability when the time when the terminal enters the coverage of the relay apparatus is before the overhearing time.

Wherein the calculating unit calculates an overhearing probability of the target terminal using the following equation,

는 상기 대상 단말이 상기 중계 장치의 커버리지내에 진입한 시점을 나타내고, 상기

는 중복 청크의 오버히어링 시점을 나타내며, 상기

는 상기 대상 단말의 전송 모드를 나타내고, 상기

는 상기 중복 청크의 전송 모드를 나타내며, 상기 l은 상기 중복 청크가 오버히어링된 시점과 현재 시점과의 차이를 나타낸다.here,

Indicates a time when the target terminal has entered the coverage of the relay apparatus,

Indicates the overhearing point of the overlapping chunks,

Indicates a transmission mode of the target terminal,

Denotes a transmission mode of the redundant chunk, and l denotes a difference between a point in time when the overlapped chunk is over-overlapped and a present point in time.

The encoding unit may encode the packet by replacing the redundant chunk with a fingerprint when the overhearing probability is equal to or greater than a threshold value.

The encoded packet may further include offset information indicating the number of the fingerprints and the position of the fingerprints.

And a retransmission management unit for extracting the packet information and the chunk corresponding to the fingerprint and retransmitting the decoded chunk corresponding to the fingerprint when the decoding error message including the packet information and the fingerprint is received from the target terminal without encoding.

According to another embodiment of the present invention, there is provided a communication apparatus including: a communication unit for receiving an encoded packet from a relay apparatus; And a decoding unit for decoding the encoded packet by extracting a chunk corresponding to the fingerprint with reference to a previously stored fingerprint table if a fingerprint exists, by analyzing the encoded packet May be provided.

And a retransmission management unit for transmitting a decoding error message including the fingerprint and the information of the packet to the relay apparatus and retransmitting the chunk corresponding to the fingerprint when the fingerprint is not stored in the fingerprint table can do.

The decoding unit may decode the encoded packet using the retransmitted chunk when a decoding error occurs.

According to another aspect of the present invention, there is provided a wireless network capable of effectively eliminating traffic redundancy by judging whether there is a redundant chunk by using only a minimum amount of information necessary for calculating an overhearing probability of a terminal in a wireless network, A removal method is provided.

According to an embodiment of the present invention, there is provided a method comprising: receiving a packet; Analyzing the packet to search for duplicate chunks; Calculating an overhearing probability of the target terminal using the channel state of the overlapping chunk and the target terminal if the overlapping chunk exists; Removing the overlapping chunks according to the calculated overhearing probability to encode the packet; And delivering the encoded packet to the target terminal.

The method and apparatus for deduplication of traffic in a wireless network according to an embodiment of the present invention can determine whether duplicated chunks are stochastically using only the minimum information necessary for calculating the overhearing probability of a terminal in a wireless network There is an advantage of effectively eliminating traffic duplication.

In addition, the present invention is advantageous in that traffic duplication can be effectively removed without a cache table synchronization between a wireless network and a terminal.

Also, the present invention has an advantage of minimizing the overhead by maintaining only the minimum information necessary for calculating the overhearing probability of the terminal.

In addition, the present invention is robust to a wireless network environment in which frequent channel changes occur in an MS by calculating an overhearing probability according to a channel state of the MS using an analytical model.

1 is a diagram illustrating overhearing in a wireless network according to an embodiment of the present invention;
FIG. 2 illustrates traffic duplication removal according to an overhearing of a terminal according to an embodiment of the present invention; FIG.
3 is a block diagram schematically showing an internal configuration of a relay apparatus according to an embodiment of the present invention;
4 illustrates a cache table according to an embodiment of the present invention.
5 is a view schematically showing a configuration of a terminal according to an embodiment of the present invention.
6 illustrates a fingerprint table according to an embodiment of the present invention.
7 is a flowchart illustrating a method of transmitting a packet by removing traffic redundancy in a relay apparatus according to an embodiment of the present invention.
8 is a diagram illustrating a structure of an encoded packet according to an embodiment of the present invention;
9 is a flowchart illustrating a method of decoding a packet encoded in a terminal according to an embodiment of the present invention.
10 is a flowchart illustrating a retransmission process according to a packet decoding failure of a UE according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

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.

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.

The present invention relates to an invention capable of calculating an overhearing probability of a terminal in a wireless network providing multiple bit rates, determining whether or not the terminal stores a chunk, and eliminating redundant chunks to transmit the packet.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating overhearing in a wireless network according to an embodiment of the present invention. Referring to FIG. It is assumed that the relay apparatus 110 is a wireless network environment in which a plurality of terminals located within the coverage of the relay apparatus 110 are managed.

In the present specification, it is assumed that a wireless network provides multiple bit rates, and each terminal can overhear a packet transmitted to another terminal.

It is assumed that there are n (natural number) transmission modes between the relay apparatus 110 and the terminals, and each transmission mode has a corresponding transmission bit rate.

It is assumed that the transmission modes having the range of the first transmission mode to the nth transmission mode are in ascending order, the first transmission mode has the lowest transmission bit rate and the nth transmission mode has the highest transmission bit rate.

The relay apparatus 110 can transmit data using the most optimal transmission mode according to the channel state of the UE. For example, if the channel state of the terminal is poor, the relay apparatus 110 transmits the packet to the terminal using the low transmission mode. If the channel state of the terminal is good, the relay apparatus 110 uses the high transmission mode And transmit the packet.

Accordingly, it is assumed that the relay apparatus 110 selects the lowest transmission mode (first transmission mode) and delivers the packet to the first terminal. The second terminal and the third terminal having relatively good channel status can overhear the packet transmitted to the first terminal.

However, it is assumed that the relay apparatus 110 selects the fifth transmission mode, which is a relatively high transmission mode, and transmits the packet to the third terminal. The probability that the first terminal and the second terminal, which have a relatively poor channel state than the channel state of the third terminal, can not receive a packet due to a bad channel state or a large number of packet errors, and thus can not overhear.

The terminal 120 may overhear the data signal transmitted to the other terminal by the relay apparatus 110 and may store the chunk acquired through the overhearing in the memory of the terminal 120. [

FIG. 2 is a diagram illustrating traffic de-duplication according to an overhearing of a UE according to an embodiment of the present invention. Referring to FIG.

As shown in FIG. 2, the relay apparatus 110 transmits a packet including a C ₃ chunk to the first terminal at a first time point, and transmits a packet including a plurality of chunks C ₁ and C ₂ at a second time point And transmits the encoded packet to the second terminal. At this time, it is assumed that the first terminal has a better channel state than the second terminal.

The first terminal having a relatively better channel state than the second terminal can over-encode the encoded packet transmitted to the second terminal and store the chunks (C ₁ and C ₂₎ in the overhearing packet in the internal memory . That is, C ₁ , C _2, and C ₃ are stored in the memory of the first terminal.

Accordingly, when the relay apparatus 110 delivers a packet including C ₁ , C _2, and C ₃ to the first terminal at a third point in time, the first terminal stores C ₁ , C _2, and C ₃ Thus, the relay apparatus 110 can deliver the encoded packet including the fingerprints corresponding to C ₁ , C _2, and C ₃ . As described above, the relay apparatus can remove the overlapping traffic by encoding the chunk obtained through the overhearing as well as the chunk stored by the first terminal through the overhearing chunk cache.

3 is a block diagram schematically illustrating an internal configuration of a relay apparatus according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a cache table according to an embodiment of the present invention.

3, a relay apparatus 110 according to an exemplary embodiment of the present invention includes a communication unit 310, a search unit 315, a calculation unit 320, an encoding unit 325, a retransmission management unit 330, (335) and a control unit (340).

And is a means for transmitting and receiving data to and from the other devices (for example, the terminal 120) through a communication network.

For example, the communication unit 310 may receive a packet through the core network and output the received packet to the retrieval unit 315 or the retransmission management unit 330. The communication unit 310 may also transmit the packet to the terminal 120 under the control of the control unit 340. [

Search unit 315 is a means for searching for duplicate chunks in the received packet.

Herein, a redundant chunk refers to a chunk that has been previously transmitted through the relay apparatus 110. [ It is natural that duplicate chunks can be plural.

More specifically, the searching unit 315 generates a fingerprint while dividing the received packet by a fixed chunk size. Then, the searching unit 315 may compare the generated fingerprint with the fingerprint stored in the cache table to determine whether the same byte sequence exists, and search for the duplicated chunk.

The cache table is illustrated in FIG. 4 as a table that stores information on previously transmitted chunks. As shown in FIG. 4, the cache table includes previously transmitted chunks, fingerprints for chunks, transmission modes, and delivery times.

The transmission mode indicates a transmission mode at the time of transmitting the chunk, and the transmission time indicates a timestamp when the chunk is transmitted.

The calculation unit 320 may include means for calculating an overhearing probability of a target terminal using information on a redundant chunk searched through the search unit 315 (hereinafter referred to as redundant chunk information) and a channel state of the target terminal to be.

For example, the calculation unit 320 may estimate the channel state of the past target UE using the current channel state and time difference of the target UE, and calculate the overhearing probability of the target UE based on the predicted channel state.

)를 예측할 수 있다. 계산부(320)는 예측된 전송 모드(

)와 중복 청크의 전송 모드를 rate adaptation 알고리즘을 적용하여 전송 모드와 채널 상태를 이용해 오버히어링 확률을 계산할 수 잇다.More specifically, the calculation unit 320 calculates a channel mobility model using a transmission mode (m _d ) according to a channel state of a target terminal with respect to a current time point, a time difference between an overhearing time (delivery time point) The transmission mode according to the channel state of the target terminal at the overhearing time (

) Can be predicted. The calculation unit 320 calculates the predicted transmission mode (

) And the transmission mode of the redundant chunks by using the rate adaptation algorithm and calculate the overhearing probability using the transmission mode and the channel state.

At this time, the calculation unit 320 can calculate the overhearing probability for the target terminal only when the time when the target terminal enters the coverage of the relay apparatus 110 is within the delivery time of the overlapping chunk (i.e., the overhearing time) .

That is, if a redundant chunk is delivered before the target terminal is located within the coverage of the relay apparatus 110, the probability of overhearing the redundant chunk in the target terminal becomes "0 ".

For example, the calculation unit 320 may calculate the overhearing probability for the target terminal 120 using the number 1.

는 대상 단말(d)가 해당 중계 장치(110) 커버리지 내로 진입한 시간을 의미한다.

는 중복 청크가 전달된 전달 시점(오버히어링 시점)을 나타내고,

은 중복 청크의 전송 모드를 나타내며, l은 현재 시점과 중복 청크가 전달된 시점간의 시간차를 나타낸다.here,

Indicates the time when the target terminal d enters the coverage of the relay apparatus 110. [

Represents the delivery time (overhearing time) at which the overlapping chunk is delivered,

Represents the transmission mode of the redundant chunk, and l represents the time difference between the present point and the point at which the redundant chunk is delivered.

As described above, the transmission mode of the target terminal in the past can be stochastically predicted using the transmission mode and the time difference according to the channel state of the target terminal using the FSMC channel transition model. Mode and the transmission mode of the redundant chunk are used to derive the packet error rate (PER) of the terminal using the transmission mode of the target terminal in the past when the packet is delivered using the redundancy chunk according to the AMC (rate adaptation) analysis model can do. '1-PER' indicates the probability of receiving a packet and can be used as an overhearing probability.

Therefore, when the average of the 1-PER values is obtained when the transmission mode of the target terminal is used, the average overhearing probability when the transmission mode of the current target terminal is used can be represented.

The encoding unit 325 is a means for determining whether or not to remove the redundant chunks according to the redundant chunk overhearing probability at the target terminal calculated by the calculation unit 320 and encoding the packet.

For example, the encoding unit 325 may encode the packet by replacing the redundant chunk with the corresponding fingerprint if the redundant chunk overhearing probability is equal to or greater than a predetermined threshold.

The retransmission management unit 330 is a means for retransmitting a packet according to a decoding error message from the target terminal. The retransmission management unit 330 may retrieve a chunk corresponding to the fingerprint in the buffer using the packet information included in the decoding error message and transmit the packet to the target terminal without encoding the chunk. This will be described in more detail below with reference to the related drawings.

The memory 335 is a means for storing various applications, received packets, and cache tables necessary for operating the relay apparatus 110 according to an embodiment of the present invention.

The control unit 340 controls the internal components (for example, the communication unit 310, the search unit 315, the calculation unit 320, and the encoding unit 325) of the relay apparatus 110 according to an embodiment of the present invention. The retransmission management unit 330, the memory 335, and the like).

FIG. 5 is a diagram schematically illustrating a configuration of a terminal according to an embodiment of the present invention, and FIG. 6 is a diagram illustrating a fingerprint table according to an embodiment of the present invention.

5, a terminal 120 according to an embodiment of the present invention includes a communication unit 510, a decoding unit 515, a retransmission management unit 520, a memory 525, and a control unit 530 .

The communication unit 510 is a means for transmitting and receiving data with other devices (for example, the relay device 110) through a communication network.

For example, the communication unit 510 may receive the encoded packet from the relay apparatus 110 and output the received packet to the decoding unit 515. Also, the communication unit 510 may transmit a response message (NAK, ACK) to the relay apparatus 110 according to the success or failure of decoding the encoded packet under the control of the control unit 530. [

The decoding unit 515 is means for decoding the encoded packet received through the communication unit 510. [

For example, if there is a fingerprint in the received encoded packet, the decoding unit 515 extracts and replaces the corresponding chunk with reference to the fingerprint table, It can be decoded. A fingerprint table is shown in Fig. The fingerprint table stores fingerprints corresponding to chunks and chunks, respectively.

However, if the fingerprint is present in the received packet but the fingerprint corresponding to the fingerprint table is not stored, the decoding unit 515 outputs a decoding failure message to the decoding unit 515. [

The retransmission management unit 520 temporarily stores the decoded packet in the buffer in accordance with the decoding failure message input from the decoding unit 515. Then, the retransmission management unit 520 requests the relay apparatus 110 to retransmit the packet and acquires the packet.

For example, the retransmission management unit 520 generates a decoding error message (NAK) including packet information (for example, packet identification information (ID) and sequence number) of the decoded packet, ).

Of course, the decoding error message may further include a fingerprint that is not stored in the fingerprint table in addition to the packet information.

The retransmission management unit 520 may receive the error response message corresponding to the decoding error message and output the chunk corresponding to the fingerprint to the decoding unit 515. [ Accordingly, the decoding unit 515 can decode the encoded packet using the chunk.

If the decoding unit 515 succeeds in decoding the packet, the retransmission management unit 520 can remove the packet stored in the buffer.

Such a retransmission process will be more clearly understood with reference to the following drawings.

The memory 525 stores various algorithms, fingerprint tables, and the like necessary for operating a terminal according to an embodiment of the present invention. Of course, it is a matter of course that various information is stored in the memory 525.

The control unit 530 may be configured to control the internal components (e.g., the communication unit 510, the decoding unit 515, the retransmission management unit 520, and the memory 525) of the terminal 120 according to an embodiment of the present invention. As shown in FIG.

FIG. 7 is a flowchart illustrating a method of transmitting a packet by removing traffic redundancy in a relay apparatus according to an embodiment of the present invention. FIG. 8 is a flowchart illustrating a method of transmitting a packet according to an exemplary embodiment of the present invention. Fig.

In step 710, the relay apparatus 110 receives the packet from the core network.

In step 715, the relay apparatus 110 determines whether the received packet is an error message due to the absence of a duplicated chunk of the terminal.

If it is an error message due to a redundant chunk member, the relay apparatus 110 forwards the unencoded packet in step 720. [

For example, when the relay apparatus 110 is an error message due to a redundant chunk of the terminal, the relay apparatus 110 extracts a chunk corresponding to the fingerprint using the packet information and the fingerprint included in the error message, To the target terminal.

However, if it is not an error message due to the redundant chunk member, the relay apparatus 110 analyzes the received packet in step 725 to search for duplicate chunks.

The relay apparatus 110 divides the received packet into predetermined chunk size units, divides the packet into chunks, and generates a fingerprint fp (c), respectively. Then, the relay apparatus 110 can determine whether duplicate chunks exist by judging whether or not the same byte sequence exists by matching the generated fingerprint with the cache table. However, if the same byte sequence does not exist, the relay apparatus 110 can determine that there is no redundant chunk. As described above, the redundant chunks may be plural.

As a result of the duplicate chunk search, in step 730, the relay apparatus 110 determines whether there is a duplicated chunk.

If there is a duplicate chunk, the relay apparatus 110 calculates an overhearing probability of the target terminal using the redundant chunk information and the channel state of the terminal in step 735.

For example, the overhearing probability can be calculated only when the time when the target terminal enters the coverage of the relay device 110 precedes the delivery time (overhearing time) of the overlapping chunk.

The relay apparatus 110 can estimate the channel state of the past target terminal using the current channel state and the time difference of the target terminal, and calculate the overhearing probability of the target terminal based on the predicted channel state. For example, an adaptation modulation and coding (AMC) model may determine a transmission mode based on a received signal-to-noise ratio (SNR) of a terminal. Also, the channel change of the UE according to time may be analyzed considering the channel transition model, or a finite-state Markov chain (FSMC) model may be applied.

)를 예측할 수 있다. 중계 장치(110)는 예측된 전송 모드(

)와 중복 청크의 전송 모드를 rate adaptation 알고리즘을 적용하여 전송 모드와 채널 상태를 이용해 오버히어링 확률을 계산할 수 있다.More specifically, the relay apparatus 110 extracts the channel mode from the channel transition model using the transmission mode m _d according to the channel state of the target terminal with respect to the current time, the time difference between the overhearing time (delivery time point) The transmission mode according to the channel state of the target terminal at the overhearing time (

) Can be predicted. The relay apparatus 110 transmits the predicted transmission mode (

) And the transmission mode of the redundant chunks by using the rate adaptation algorithm, the overhearing probability can be calculated using the transmission mode and the channel state.

)에 대응하는 대상 단말의 오버히어링 확률 계산이 완료되면, 단계 740에서 중계 장치(110)는 계산된 오버히어링 확률이 임계치 이상인지 여부를 판단한다.In this way,

, The relay apparatus 110 determines in step 740 whether the calculated overhearing probability is equal to or greater than a threshold value.

If the calculated overhearing probability is greater than or equal to the threshold value, the relay apparatus 110 determines that the corresponding overlapping chunk is stored in the target terminal in step 745, and encodes it by replacing it with the fingerprint corresponding to the overlapping chunk.

8 is a diagram illustrating an invention for encoding a packet.

As shown in FIG. 8, the encoded packet includes a fingerprint offset area and a data area. Of course, the header portion of the encoded packet may include a fixed size area indicating the number of fingerprints. The fingerprint offset region may include offset information indicating the fingerprint original position in the packet.

Then, in step 750, the relay apparatus 110 updates the cache table.

Then, in step 755, the relay apparatus 110 transmits the encoded packet.

However, if the calculated overhearing probability is less than the threshold, the process proceeds to step 650.

9 is a flowchart illustrating a method of decoding an encoded packet in a terminal according to an embodiment of the present invention.

In step 910, the terminal 120 receives a packet from the relay apparatus 110. [ Here, the packet may be an encoded packet or an unencoded packet.

In step 915, the terminal 120 determines whether a fingerprint exists in the received packet.

If there is no fingerprint in the packet, the terminal 120 updates the fingerprint table in step 920.

However, if there is a fingerprint in the packet, it is determined that the packet is an encoded packet. In step 925, the terminal 120 compares the packet with the previously stored fingerprint table to check if the same fingerprint exists.

If the same fingerprint exists, then in step 930, the terminal 120 refers to the fingerprint table and replaces the same fingerprint with the corresponding chunk.

Then, in step 935, the terminal 120 decodes the encoded packet.

However, if the same fingerprint does not exist in the fingerprint table, the terminal 120 transmits an error message corresponding to decoding failure to the relay apparatus 110 in step 940.

That is, the terminal does not have the same fingerprint in the fingerprint table, and can not decode the normally encoded packet. Accordingly, an error message related to decoding failure can be transmitted to the relay apparatus 110 to perform a retransmission process. The retransmission process will be described in more detail with reference to FIG. 9 below.

FIG. 10 is a flowchart illustrating a retransmission process according to a packet decoding failure of a UE according to an embodiment of the present invention.

In step 1010, the terminal 120 temporarily stores the decoded packet in the buffer as the decoding fails because the fingerprint included in the encoded packet is not stored in the fingerprint table.

In step 1015, the AT 120 transmits a decoding error message (NAK) including packet identification information for identifying the decoded packet to the relay apparatus 110.

Here, the packet identification information may be an ID and a sequence number of a decoded packet (encoded packet). The packet identification information can be applied equally to all the information that can identify a specific packet.

In step 1020, the relay apparatus 110 extracts packet identification information from the decoding error message according to reception of the decoding error message from the terminal 120, and searches for a chunk corresponding to the packet identification information. At this time, it is natural that there may be plural chunks retrieved.

Then, in step 1025, the relay apparatus 110 transmits a packet including the searched chunk to the terminal 120. The packet retransmitted by the relay apparatus 110 may be an unencoded packet.

In step 1030, the terminal 120 extracts the chunk from the received packet and decodes the decoded packet using the chunk.

For example, after extracting a chunk from a received packet, the encoded chunk may be used to replace the fingerprint of the decoded packet with a chunk and then decode the encoded packet.

Then, in step 1035, the terminal 120 transmits a decoding success message (ACK) to the relay apparatus 110. As described above, after transmitting the decoding success message to the relay apparatus, the terminal 120 can remove the decoding failure packet temporarily stored in the buffer.

Then, the relay apparatus 110 can also remove the packet temporarily stored in the buffer when a decoding success message is received from the terminal 120. [

Meanwhile, the traffic duplication cancellation method in a wireless network according to an embodiment of the present invention may be implemented in a form of a program command that can be executed through a variety of electronic information processing means and recorded in a storage medium. The storage medium may include program instructions, data files, data structures, and the like, alone or in combination.

Program instructions to be recorded on the storage medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of software. Examples of storage media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, magneto-optical media and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as devices for processing information electronically using an interpreter or the like, for example, a high-level language code that can be executed by a computer.

The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

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 invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

110: Relay device
120: terminal

Claims (14)

A communication unit for receiving a packet from the core network;
An encoding unit for removing redundant chunks of the packet and encoding the packet according to overhearing of a target terminal considering a transmission mode of the packet; And
And a retransmission management unit for extracting the packet information and a chunk corresponding to the fingerprint and retransmitting the decoded chunk corresponding to the fingerprint when the decoding error message including the packet information and the fingerprint is received from the target terminal without encoding,
And the encoded packet is transmitted to the target terminal through the communication unit. The method according to claim 1,
A searching unit for analyzing the packet and searching for the duplicated chunk; And
And a calculation unit for calculating an overhearing probability using the overlapping chunk information and the channel state of the target terminal if the search result of the search unit includes a duplicate chunk,
Wherein the encoding unit determines whether to encode the overlapping chunk by replacing the overlapping chunk with a previously stored fingerprint according to the calculated overhearing probability.

3. The method of claim 2,
The search unit may search,
Dividing the packet into a predetermined chunk size to generate a fingerprint for each chunk, and searching for the duplicated chunk by searching whether the generated fingerprint is stored. 3. The method of claim 2,
Wherein the calculation unit applies the multiple bit rate model using the time difference between the overhearing time and the current time of the overlapping chunks and the transmission mode of the target terminal at the current time to determine a channel state of the target terminal at the overhearing time of the overlapping chunks And estimates an overhearing probability of the target terminal using the predicted channel state and the transmission mode of the overlapping chunk. The method of claim 3,
Wherein the calculation unit estimates a transmission mode according to a channel state of the target terminal at an overhearing time of the overlapping chunk by applying a rate adaptation algorithm. The method of claim 3,
Wherein the calculation unit calculates the overhearing probability when the time when the terminal enters the coverage of the relay apparatus is before the overhearing time. 3. The method of claim 2,
Wherein the calculation unit calculates an overhearing probability of the target terminal using the following equation.

here,

Indicates a time when the target terminal has entered the coverage of the relay apparatus,

Indicates the overhearing point of the overlapping chunks,

Indicates a transmission mode of the target terminal,

Denotes a transmission mode of the redundant chunk, and l denotes a difference between a point in time at which the redundant chunk is over-overlapped and a current point in time. 3. The method of claim 2,
The encoding unit may include:
And replaces the redundant chunk with a fingerprint to encode the packet if the overheard probability is equal to or greater than a threshold value. 9. The method of claim 8,
Wherein the encoded packet further includes offset information indicating the number of the fingerprints and the position of the fingerprints. delete A communication unit for receiving the encoded packet from the relay apparatus;
A decoding unit for analyzing the encoded packet to determine whether a fingerprint exists, extracting a chunk corresponding to the fingerprint by referring to a previously stored fingerprint table if a fingerprint exists, and decoding the encoded packet; And
And a retransmission management unit for transmitting a decoding error message including the fingerprint and the information of the packet to the relay apparatus and retransmitting the chunk corresponding to the fingerprint when the fingerprint is not stored in the fingerprint table ,
The relay apparatus includes:
And upon receipt of the decoding error message including the fingerprint and the information of the packet, extracts the chunk corresponding to the packet information and the fingerprint and retransmits the chunk without encoding. delete 12. The method of claim 11,
Wherein the decoding unit decodes the encoded packet using the retransmitted chunk when a decoding error occurs. Receiving a packet;
Analyzing the packet to search for duplicate chunks;
Calculating an overhearing probability of the target terminal using the channel state of the overlapping chunk and the target terminal if the overlapping chunk exists;
Removing the overlapping chunks according to the calculated overhearing probability to encode the packet; And
And transmitting the encoded packet to the target terminal,
Wherein the encoding step comprises:
And if the overhearing probability is equal to or greater than the threshold value, replacing the redundant chunk with a fingerprint to encode the packet.

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