KR101429398B1 - Method for porcessing scalable coding-baced data - Google Patents

Abstract

The present invention relates to a method of processing scalable coding based data, which is capable of reducing retransmission of data. A method of processing data according to one embodiment of the present invention, which receives scalable coding data hierarchically coded through a delay-ACK scheme, includes the steps of: receiving a delay-ACK request message and data frames of each layer, wherein the data frames of each layer is received through each independent channel and a loss exists in the data frame of at least one layer among the data frames of each layer; calculating the minimum number of data frames required in decoding at each layer based on a decoding success rate required by each layer; determining the number of retransmitted data frames of at least one layer having a loss by using the calculated minimum number of required data frames and channel state information; and requesting data retransmission to a transmission node based on the determined number of retransmitted data frames.

Description

[0001] METHOD FOR PORCESSING SCALABLE CODING-BACED DATA [0002]

The present invention relates to a scalable coding-based data processing method, and more particularly, to a scalable coding-based data processing method capable of reducing retransmission of data.

Various video devices such as smart TVs, smart phones, tablet PCs, and laptops require various service qualities depending on various resolutions and network conditions. In particular, due to the generalization of smart phones and tablet PCs, one content is used in various resolutions and various network environments suitable for each device. In order to provide high-quality contents suitable for such various environments, there is a limit to a video encoding method that supports the existing single format. Therefore, we use scalable video coding (SVC) which can use one content according to the network condition.

scalable video coding is an extended standard in the H.265 / AVC standard, which hierarchically encodes an input image so that it can be decoded from a single encoded bit stream at various resolutions and frame rates.

FIG. 1 shows a process of encoding and decoding scalable video coding. This property is called scalability, and scalable video coding provides scalability in terms of time, space, and image quality. Currently, compression standards such as H.265 / AVC and MPEG-4 use a single layer and can not operate efficiently in different environments. However, since scalable video coding provides three determinations of time, space and image quality, It is a video compression standard that can provide optimal quality depending on network conditions and devices. This scalable video coding is designed to adapt to various device and network conditions. To support various resolutions and various image quality, one multimedia streaming data is divided into several layers and transmitted. The scalable video coding is composed of a base layer and a plurality of enhancement layers.

On the other hand, when data is transmitted in a wireless network environment, frame errors and loss occur frequently.

Recently, when frame errors and loss occur, methods for efficiently solving the problems are emerging.

Japanese Patent Application No. 10-0926669 divides the content to be transmitted into blocks of a predetermined size, encodes the blocks using an erasure resilient code, collects encoded blocks of predetermined sizes, A transmitting end constituting a frame which is a unit; And a receiving end for receiving the frame from the transmitting end, discarding a block in which an error occurred, discarding a block in which no error has occurred, and using the extracted block for retransmission or decoding.

However, the above-mentioned Japanese Patent No. 10-0926669 discloses only a technique of retransmitting data by checking only whether data has been erroneously generated, and does not disclose a technique of transmitting data in consideration of the current network state.

Therefore, it is necessary to study the data processing method of receiving data in consideration of the current network condition.

An object of the present invention is to provide a scalable coding-based data processing method for determining retransmission data corresponding to lost data using channel state information.

According to an aspect of the present invention, there is provided a data processing method for receiving scalable coding data hierarchically coded by a Delay-ACK technique, the data processing method comprising: receiving a Delay- Wherein the data frames for each layer are received over independent channels, and the data frames of at least one of the data frames of each layer are lossy data frames; Calculating a minimum number of necessary data frames necessary for decoding in each layer based on a decoding success rate required in each layer; Determining a number of retransmission data frames of at least one layer with loss using the calculated minimum required number of data frames and channel state information; And requesting the transmitting node to retransmit the data based on the determined number of retransmission data frames.

The data processing method according to an embodiment of the present invention can efficiently process scalable coding based data.

The data processing method according to an embodiment of the present invention determines the retransmission data corresponding to the lost data based on the channel state information, thereby reducing retransmission of data.

1 is a diagram for explaining general scalable video coding.
2 is a diagram for explaining erasure coding related to an embodiment of the present invention.
3 is a diagram for explaining a method of transmitting data using a Delay-ACK technique according to an embodiment of the present invention.
4 is a flow chart illustrating a data processing method in accordance with an embodiment of the present invention.
5 to 8 are views for explaining an example of data retransmission in a scalable coding-based data processing method according to an embodiment of the present invention.

Hereinafter, a scalable coding-based data processing method according to an embodiment of the present invention will be described with reference to the drawings.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In this specification, the terms "comprising ", or" comprising "and the like should not be construed as necessarily including the various elements or steps described in the specification, Or may be further comprised of additional components or steps.

The data processing method according to an embodiment of the present invention includes a method of transmitting and receiving data hierarchically coded by a scalable coding method using an erasure coding method and a delay-ACK method .

First, a Delay-ACK scheme and erasure coding according to an embodiment of the present invention will be described.

2 is a diagram for explaining erasure coding related to an embodiment of the present invention.

When data is transmitted in a wireless network environment, frame errors and loss occur frequently. FEC (Forward Error Correction) technique and ACK (acknowledge) transmission technique are used for reliable transmission in order to quickly recover data loss on the network. As a technique for video transmission during the FEC technique, a method of correcting errors by adding additional bits in the application layer can be used. One of these techniques, erasure coding technique, is a kind of error control code. It combines several data packets into one transmission group (TG), applies linear block code, adds additional bits, and generates a new packet set .

As shown, if the number of data to be transmitted is K in the transmitting node, N TGs are generated through an encoder (N> = K). This coding scheme is called the (N, K) coding scheme. The receiving node can recover K original data through a decoder even if only R TGs equal to or greater than K among N encoded TGs are received.

The ACK transmission scheme is a method in which data is transmitted from a transmitting side, and an ACK message is transmitted when a receiving side receives data and normally receives data. There are various ACK transmission schemes according to the wireless communication standard. Among them, the Delay-ACK scheme is a method that minimizes the ACK transmission load on the wireless channel.

3 is a diagram for explaining a method of transmitting data using a Delay-ACK technique according to an embodiment of the present invention.

As shown in the figure, the Delay-ACK scheme refers to a scheme of transmitting one ACK for confirming the reception of multiple data transmissions. The transmitting node sends a Delay-ACK request message to the receiving node to use the Delay-ACK method. On the other hand, the receiving node transmits the buffer information of the current receiving node to the transmitting node through the Delay-ACK response message, and the transmitting node determines the size of the burst to be transmitted at one time. Thereafter, the transmitting node transmits data to the receiving node, and the data frame in one burst is continuously transmitted without transmitting another ACK.

On the other hand, in the case of the last data frame in the burst, the information including the information indicating that the burst ends and the request information for the burst transmission newly started are transmitted. Therefore, in the case of the last data frame, retransmission is performed until ACK for the corresponding burst is received. After receiving the last data of the burst, the receiving node generates the buffer information of the receiving node together with the ACK frame based on the data frame received so far, and transmits the buffer information to the transmitting node. The transmitting node that received the ACK frame performs retransmission on the lost data frame. The Delay-ACK scheme is more effective than the Immediate-ACK scheme that transmits ACK frames for each data because it reduces the overhead due to the ACK frame.

Hereinafter, a method of transmitting and receiving scalably coded video data that is hierarchically coded using an erasure coding and a delay-ACK technique will be described. Hereinafter, it is assumed that an encoder and a decoder for erasure coding and scalable video coding are present in the application layer of the transmitting node and the receiving node. It is also assumed that the data link layer can grasp the coding related information of the application layer.

The data processing method according to an embodiment of the present invention can use both erasure coding and scalable video coding. Scalable video coding considers that a base layer and an enhancement layer exist independently of each other. Each base layer and enhancement layer are divided into independent erasure coding. When transmitting data in a wireless network, it is assumed that the base layer and the enhancement layer are independent channels. The notations used in this specification can be summarized as shown in Table 1 below.

Number of frames required for decoding at the receiving node of the base (enhancement) layer

Number of successfully received frames in the receiving node of the base (enhancement) layer

At the sending node in the base (enhancement) layer, Burst  size

Number of retransmissions in the base (enhancement) layer

Decoding success rate required by base (enhancement) layer ( threshold )

Frame transmission loss rate of the base (enhancement) layer

In the base (enhancement) layer

Decoding success rate when retransmitting

4 is a flow chart illustrating a data processing method in accordance with an embodiment of the present invention.

First, the transmitting node 100 may transmit a Delay-ACK request message to the receiving node 200 in order to use the Delay-ACK technique (S1). Accordingly, the receiving node 200 can transmit the buffer information of the current receiving node 200 to the transmitting node 100 through the Delay-ACK response message (S2).

The transmitting node 100 can determine the size of a burst to transmit the Delay-ACK response message at a time.

The transmitting node 100 may generate D _B base layer data frames and D _E data layer enhanced layers according to the determined size of the burst (S3). The transmitting node 100 may continuously transmit the generated data frame to the receiving node 200 (S4). The data frames for each layer may be transmitted over independent channels. In the last frame of each layer, request information for a newly started burst transmission may be included together with information indicating that the corresponding burst is ended in the last data frame in the burst.

The receiving node 200 can check errors such as errors or loss of the received D _B base layer data frames and D _E improvement layer data frames (S5).

)가 디코딩을 위해 필요한 프레임 개수(

)보다 크거나 같은지 여부를 판단할 수 있다.In the error checking process, the receiving node 200 calculates the number of frames

) Is the number of frames needed for decoding (

) Or not.

)가 디코딩을 위해 필요한 프레임 개수(

)보다 크거나 같다면 전송에 성공한 것으로 판단될 수 있다. 이 경우, 수신 노드(200)는 데이터 프레임의 전송 오류가 없다는 ACK 메시지를 송신 노드(100)에 전송할 수 있다(S9).If the number of frames received in each layer (

) Is the number of frames needed for decoding (

), It can be determined that the transmission is successful. In this case, the receiving node 200 can transmit an ACK message to the transmitting node 100 that there is no transmission error of the data frame (S9).

의 개수가

보다 작을 경우, 수신 노드(200)는 Delay-ACK을 이용하여 재전송 요청 메시지를 상기 송신 노드(200)에 전송할 수 있다.However,

The number of

The receiving node 200 may transmit a retransmission request message to the transmitting node 200 using Delay-ACK.

When retransmission is performed in each layer, if all the lost frames are retransmitted, additional retransmission occurs in addition to the number of frames required for recovery. However, if only the minimum amount of data necessary for recovery (i.e., decoding) is to be retransmitted, a retransmission frame may be lost due to a channel state during transmission of a retransmission frame, so that additional retransmission may be required.

)을 포함할 수 있다.Therefore, the receiving node 200 can determine the number of frames to request retransmission based on channel state information of each layer (S6). The channel state information includes a frame transmission loss rate of each layer

).

The receiving node 200 may transmit an ACK message including the number of data frames to be retransmitted to the transmitting node 100 (S7).

The transmitting node 100 can retransmit the data frame of the server in which the loss occurs due to the received ACK message (S8).

)와 현재 채널 상태를 고려하여 상기 송신 노드(100)에 재전송을 요청할 수 있다. That is, when the receiving node 200 does not request retransmission for all data lost when requesting retransmission,

) And the current channel state to request the retransmission of the transmission node (100).

라고 하면, 각 계층에서 요구하는 디코딩 성공률(

) 보다 높은 디코딩 성공률(

)을 보장할 수 있는 최소한의

를 찾을 수 있다. 여기서

는 기본 (향상) 계층에

개를 재전송 할 때, 기본 (향상)계층이 디코딩에 성공할 확률을 나타낸다. 각 계층이 독립 채널이라고 가정할 경우 각 계층의 프레임 전송 손실률(

)를 이용하여

을 구할 수 있다.The receiving node 200 calculates the number of retransmissions in each layer

, The decoding success rate required by each layer (

) Higher decoding success rate (

) To ensure the minimum

Can be found. here

In the base (enhancement) layer

When retransmitting a dog, it indicates the probability that the base (enhancement) layer will succeed in decoding. Assuming that each layer is an independent channel, the frame transmission loss ratio (

)

Can be obtained.

In the case of erasure coding considering only two layers of the base layer and the enhancement layer of scalable video coding, four situations occur after the first transmission as shown in FIGS. 5 to 8.

5 to 8 show a situation in which the transmitting node transmits six frames of the base layer and seven frames of the enhancement layer. In FIGS. 5 to 8, the number N _B of data frames of the base layer required for decoding is 6, and the number of data frames N _E required for decoding of the enhancement layer is 6.

FIG. 5 shows a case where as many frames as necessary for decoding are received in both the base layer and the enhancement layer.

In the case shown in FIG. 5, since all layers are decodable, there is no need to retransmit. The receiving node 200 does not request retransmission of data because one frame is lost in each layer but decoding is possible using erasure coding.

FIG. 6 shows a case in which the number of frames required for decoding only the base layer is received.

)보다는 같거나 작아야 하며, 디코딩 시 필요한 최소의 필요 데이터 개수(

)보다는 커야 한다. FIG. 6 shows a case in which only the base layer receives as many frames as necessary for decoding, and it is necessary to retransmit the data frame of the enhancement layer. Here, the number of retransmission requests in the enhancement layer is the total number of lost frames

), And the minimum number of necessary data required for decoding (

).

)을 고려하여, 최적의 재전송 개수(

)를 선택해야 한다.

개의 프레임을 재전송한다고 할 경우 향상 계층에서 디코딩 성공률

을 구하면 수학식 1로 표현될 수 있다.The receiving node 200 calculates a frame transmission loss rate

), The optimal number of retransmissions (

) Should be selected.

Frames are retransmitted, the decoding success rate

Can be expressed by Equation (1).

을 만족하는 최소의

을 재전송 요청 개수로 선택할 수 있다. 만약, 수신 노드(200)는 응용 계층의 요구 성공률이 너무 높거나 채널 상태가 좋지 않아

을 만족하는

가 존재하지 않을 경우 손실된 모든 프레임 개수(

)만큼의 재전송을 송신 노드(100)에 요청할 수 있다.Herein, the receiving node 100 must satisfy the success rate required for the application layer because the value of the decoding success rate of the enhancement layer

Minimum

Can be selected as the number of retransmission requests. If the receiving node 200 determines that the required success rate of the application layer is too high or the channel condition is not good

Satisfy

The number of all lost frames (

) To the transmitting node 100 as shown in FIG.

In this case, the receiving node 200 has one frame loss in the base layer, but decoding is possible using erasure coding. However, the receiving node 200 requests a retransmission due to loss of decoding or the like in the enhancement layer. The receiving node 200 can request retransmission of only three frames since four frames are lost, but decoding is possible even if only three frames are transmitted.

FIG. 7 shows a case where the base layer does not receive as many frames as necessary for decoding, and receives only as many enhancement layers as necessary for decoding.

)를 결정할 수 있다.7 shows a case where the base layer does not receive as many frames as necessary for decoding, and only the enhancement layer receives as many frames as necessary for decoding. In this case, the receiving node 200 transmits retransmission of the base layer to the number of requests (

Can be determined.

The receiving node 200 may also request only two retransmissions, although three lost frames have occurred in the base layer.

8 shows a case where the number of frames required for decoding is not received in both the base layer and the enhancement layer.

)과 향상 계층에서 요구하는 디코딩 성공률(

)을 동시에 만족하는 재전송 개수(

)를 함께 결정해야 한다. FIG. 8 shows a case where the number of frames required for decoding is not received in both the base layer and the enhancement layer. In this case, the receiving node 200 considers both the base layer and the enhancement layer,

) And the decoding success rate required by the enhancement layer

) Simultaneously satisfy the retransmission count (

) Together.

개의 프레임을 재전송할 경우 디코딩 성공률을 수학식 2에 의해 결정할 수 있다.First, in order to select the number of retransmissions of the base layer,

When the frame is retransmitted, the decoding success rate can be determined by Equation (2).

을 계산 후, 기본 계층에서 요구하는 디코딩 성공률(

)을 만족시키는 최소의

을 찾고, 여기서 계산 된

값을 이용하여 향상 계층의 디코딩 성공률

을 계산할 수 있다. 향상 계층의 디코딩 성공률은 기본 계층이 디코딩이 성공을 해야 향상 계층의 디코딩이 가능하다. By the equation (2)

, The decoding success rate required by the base layer (

) ≪ / RTI >

≪ / RTI >

The success rate of decoding of the enhancement layer using the value

Can be calculated. The decoding success rate of the enhancement layer can be decoded if the base layer has successfully decoded the enhancement layer.

개의 프레임을 재전송 한다고 할 때 디코딩 성공률은 수학식 3으로 나타낼 수 있다.Therefore,

And the decoding success rate can be expressed by Equation (3).

값을 이용하여 향상 계층에서 요구하는 디코딩 성공률(

)을 만족하는 만족 시키는 최소의

값을 찾는다. 만약 현재 선택된 기본 계층의 재전송 개수

값에서 향상 계층에서 요구하는 디코딩 성공률(

)을 만족 시키는

값이 없다면

값을 증가시키면서 만족하는 최소의

값을 찾는다. 이렇게 선택된

값은 기본 계층에서의 재전송 개수(

)가 되고, 선택된

값은 향상 계층에서의 재전송 개수(

)가 된다. 하지만 이 조건을 만족시키는

,

값이 존재 하지 않으면, 수신 노드(200)는 각 계층에서 손실된 모든 프레임 개수(

) 만큼 재전송을 송신 노드(100)에 요청할 수 있다.The receiving node (200)

The decoding success rate required by the enhancement layer (

) Satisfying a minimum satisfying condition

Find the value. If the retransmission count of the currently selected base layer

Value, the decoding success rate required by the enhancement layer (

)

If there is no value

As you increase the value,

Find the value. So selected

The value is the number of retransmissions in the base layer (

), And selected

The value is the number of retransmissions in the enhancement layer (

). However,

,

If there is no value, the receiving node 200 determines the total number of frames lost in each layer (

) To the transmitting node 100. In this case,

The receiving node 200 can not decode three losses in the base layer and two losses in the enhancement layer. Therefore, the receiving node 200 transmits a Delay-ACK to the transmitting node 100 to request retransmission of the data frame. The receiving node 200 may determine the optimal number of retransmissions in each layer and then request retransmission of the data frame. In this case, since the erasure coding is used, the receiving node 200 can request retransmission of only the minimum decodable frame without requesting retransmission of all lost frames. Therefore, the receiving node 200 can request retransmission of two frames in the base layer and one frame in the enhancement layer.

The above-described data processing method may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable recording medium. At this time, the computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination. On the other hand, the program instructions recorded on the recording medium may be those specially designed and configured for the present invention or may be available to those skilled in the art of computer software.

The computer-readable recording medium includes a magnetic recording medium such as a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, an optical medium such as a CD-ROM and a DVD, a magnetic disk such as a floppy disk, A magneto-optical media, and a hardware device specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

The recording medium may be a transmission medium, such as a light or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, and the like.

The program instructions also include machine language code, such as those generated by the compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. 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.

The above-described data processing method is not limited to the configuration and method of the embodiments described above, but the embodiments may be modified so that all or some of the embodiments are selectively combined .

100: transmitting node
200: receiving node

Claims (5)

A data processing method for receiving scalably coded data hierarchically coded by a Delay-ACK technique,
Receiving a Delay-ACK request message and a data frame of each layer, the data frames for the respective layers are received through independent channels, and the data frames of at least one layer of the data frames of each layer are lost A data frame;
Determining a minimum number of data frames capable of ensuring a retransmission decoding success rate higher than a decoding success rate required by each layer as the number of retransmission data frames of at least one layer having a loss, The retransmission decoding success rate is calculated using a frame transmission loss rate of each layer; And
And requesting the transmitting node to retransmit the data based on the determined number of retransmission data frames. delete delete delete The method of claim 1, wherein the step of determining the number of retransmission data frames
Determining a number of retransmission data frames of the base layer; And
And determining the number of frames of the enhancement layer using the number of retransmission data frames of the base layer.

Images