KR101781632B1 - System for transmitting video and method for controlling length of spreading code in the same - Google Patents

System for transmitting video and method for controlling length of spreading code in the same Download PDF

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KR101781632B1
KR101781632B1 KR1020150164153A KR20150164153A KR101781632B1 KR 101781632 B1 KR101781632 B1 KR 101781632B1 KR 1020150164153 A KR1020150164153 A KR 1020150164153A KR 20150164153 A KR20150164153 A KR 20150164153A KR 101781632 B1 KR101781632 B1 KR 101781632B1
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South Korea
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layer
code
code length
signal
spreading
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KR1020150164153A
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Korean (ko)
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KR20170059767A (en
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이계산
한두희
김균탁
신현송
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경희대학교 산학협력단
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/146—Data rate or code amount at the encoder output
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00—Television systems
    • H04N7/08—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division

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  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

A video transmission system and a method for adjusting a spreading code length in the system are disclosed.
In this system, a transmitting apparatus receives a video data and outputs a Scalable Video Coding (SVC) bitstream, in which an SVC bitstream is combined with a base layer signal to be transmitted and a base layer signal And a spreading code of a different length is applied to each layer signal according to the importance of the encoded layer signal. The receiving apparatus receives the video signal of the SVC bitstream transmitted from the transmitting apparatus, despreads it by applying a code length spreading code applied in each layer in the transmitting apparatus, and outputs the video data generated by SVC decoding. Here, the transmitting apparatus and the receiving apparatus set the longest code length in the base layer signal and the code length in the form of decreasing the half-length from the code length set in the base layer signal as the importance of the enhancement layer signal becomes lower . In addition, the length of a spreading code applied to each layer according to a layer-by-layer channel state may be adaptively changed.

Description

TECHNICAL FIELD [0001] The present invention relates to a video transmission system and a spread code length control method thereof,

The present invention relates to a video transmission system and a method of adjusting a spreading code length in the system.

The SVC (Scalable Video Coding) technique has attracted attention as an effective method in a situation where a video transmission system has to transmit an image to a plurality of terminals.

Since the type and performance requirements of the terminal receiving the video transmitted by the video transmission system are different, it is difficult to use the video having only one quality for various purposes.

In the SVC scheme, a plurality of images having various resolutions and various frames are transmitted in order to transmit an image, so that an image can be selected and reproduced according to a receiving terminal.

The SVC scheme is divided into a base layer, which is a minimum signal for image reproduction, and N (N is a natural number) enhanced layer, which plays a role of improving received image quality by combining with a base layer.

The signals of these two layers have different importance, and the required bit error rate (BER) performance is also different in each layer.

According to the SVC scheme, a video signal transmitted from a video transmission system enables high-quality video bitstream coding in transmitting high-quality moving picture information through a communication network.

However, since the conventional SVC scheme allocates the same amount of bandwidth to each layer, a limitation remains in a limited system bandwidth.

SUMMARY OF THE INVENTION The present invention provides an image transmission system capable of providing an efficient performance in a limited transmission environment and capable of configuring a communication network for efficient video signal transmission and a method of adjusting a spreading code length in the system.

According to one aspect of the present invention,

A scalable video coding (SVC) bitstream, wherein the SVC bitstream comprises a base layer signal to be transmitted and at least one enhancement layer signal, which is combined with the base layer signal and improves the quality of the video information, ≪ / RTI > A spreading code generator for generating spreading codes according to preset code lengths of layers; And a spreader for spreading each layer signal of the SVC bit stream encoded and output by the encoder by applying a spreading code for each layer generated in the spreading code generator.

The spreading code generator may further include a code length setting unit that adjusts a code length set for each layer according to a channel state of each layer fed back from a receiving apparatus, And a spreading code is generated and provided to the spreader.

The code length setting unit may increase a code length for a layer determined to be worse than a previous channel state based on the channel state for each layer.

In addition, when it is determined that the channel state is improved by the layer-by-layer channel state for the layer set to increase the code length, the code length set for the layer is decreased.

The code length setting unit may increase or decrease a code length of a spreading code set for each layer according to a request performance fed back from two or more receiving apparatuses.

The code length setting unit may reduce only the code length set for the remaining enhancement layers excluding the code length set for the base layer when the code length set for each layer is decreased according to the requested performance.

According to another aspect of the present invention,

A spreading code generator for generating spreading codes according to preset code lengths of layers; An SVC bitstream transmitted from a transmitting apparatus, wherein the SVC bitstream is divided into a base layer signal to be transmitted and at least one enhancement layer signal, which is combined with the base layer signal and improves the quality of the moving picture information A despreader for despreading a signal by applying a spreading code for each layer generated in the spreading code generator; And a decoder that combines the SVC bitstream output from the despreader and outputs the combined image data.

Here, a channel estimation unit estimates a channel state for each layer using the video signal received from the transmission apparatus and feeds back the estimated channel state to the transmission apparatus; And a code length setting unit that adjusts a code length set for each layer according to a channel state of each layer estimated by the channel estimating unit, wherein the spreading code generator adjusts a code length according to a code length adjusted by the code length setting unit And a spreading code for each layer is generated and provided to the despreader.

In addition, the channel estimator estimates a channel state of each layer of the currently received video signal by comparing the channel state of each layer estimated through the previously received video signal.

According to another aspect of the present invention,

There is provided a method for adjusting the length of a spreading code, the method comprising the steps of: receiving a base layer signal to be transmitted and an SVC bitstream, the base layer signal having at least one Setting a code length for each layer corresponding to a layer of the enhancement layer signal as a basic code length; Spreading the layer-by-layer signal using a spreading code generated for each layer according to the basic code length and transmitting the spreading signal to a receiving device; Determining whether there is a layer whose channel state is changed based on the channel state information for each layer when the channel state information for each layer is fed back from the receiving apparatus; Adjusting a code length for each layer by increasing or decreasing a code length for a layer whose channel state is changed when there is a layer whose channel state is changed; And spreading the layer-by-layer signal using a spreading code generated for each layer according to a layer-by-layer code length to be adjusted and transmitting the spread signal to the receiving apparatus.

Here, in the setting of the basic code length, the basic code length is the longest code length set for the base layer signal, and as the importance of the enhancement layer signal becomes lower, 2 < / RTI > length.

According to another aspect of the present invention, there is provided a method of adjusting a code length of a layer, the method comprising: determining whether a channel state of each layer is worse than a state of each layer; Increasing a code length for a layer in which a channel state per layer is deteriorated when the channel state per layer is deteriorated; And setting a code length of the layer having a better channel state per layer when the channel state per layer is improved.

According to another aspect of the present invention,

A scalable video coding (SVC) bitstream, wherein the SVC bitstream is composed of a base layer signal to be transmitted and at least one enhancement layer signal combined with the base layer signal, And a spreading code having a different length for each layer signal according to the importance of each encoded layer signal and transmitting the spreading code; And a receiving apparatus for receiving the video signal of the SVC bitstream transmitted from the transmitting apparatus, despreading the video signal by applying a code length spreading code applied in each layer in the transmitting apparatus, and outputting the video data generated by SVC decoding .

Here, the transmitting apparatus includes: an encoder for encoding image data into the SVC bitstream; A first spreading code generator for generating spreading codes according to preset code lengths of layers; And a spreader for applying a spreading code for each layer generated in the first spreading code generator to each layer signal of the SVC bit stream encoded and output by the encoder.

The receiving apparatus may further include: a second spreading code generator for generating a spreading code according to a code length of a layer having a code length equal to a code length of each layer generated in the first spreading code generator; A despreader for despreading the video signal of the SVC bitstream transmitted from the transmitter by applying a spreading code for each layer generated in the second spreading code generator; And a decoder that combines the SVC bitstream output from the despreader and outputs the combined image data.

In addition, the receiving apparatus grasps a channel state for each layer through channel estimation of a received layer-by-layer signal, feeds back the signal to the transmitting apparatus, and the transmitting apparatus notifies the previous layer And the spreading code is generated by increasing or decreasing the length of the spreading code with respect to the hierarchy in which the channel state has changed compared to the separate channel state.

The code length of each layer may be determined by setting the longest code length in the base layer signal and decreasing the code length by one half of the code length set in the base layer signal as the importance of the enhancement layer signal becomes lower .

In addition, the spreading code is an OVSF (Orthogonal Variable Spreading Factor) code. A spreading code applied to a layer signal having a low importance is allocated to a spreading code applied to a layer signal having a high importance and a spreading code .

According to the present invention, for a different image quality requirement occurring in an environment in which a plurality of receiving apparatuses exist, by using a spreading code of a differential length without using a spreading code of the same length between layers, efficient performance is achieved in a limited transmission environment .

In addition, a communication network for efficient video signal transmission can be configured through the above.

Also, it is possible to derive the performance satisfying the video signal transmission performance by adaptively changing the length of the spreading code according to the channel state per layer while applying the differential spreading code length for each layer.

1 is a block diagram illustrating a schematic configuration of a video transmission system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a code that can be used when selecting a code of SF = 8 in the image transmission system according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating a schematic configuration of a video transmission system according to another embodiment of the present invention.
4 is a flow diagram of a method for adaptively adjusting the length of a spreading code according to another embodiment of the present invention.
FIG. 5 is a specific flowchart of a method of adjusting a code length per layer according to the channel state shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms " part, "" module," and " module ", etc. in the specification mean a unit for processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software have.

Hereinafter, a video transmission system according to an embodiment of the present invention will be described with reference to the drawings.

1 is a block diagram illustrating a schematic configuration of a video transmission system according to an embodiment of the present invention.

1, the image transmission system 10 according to the embodiment of the present invention includes a transmission apparatus 100 and a reception apparatus 200. [ In FIG. 1, in the image transmission system 10 according to the embodiment of the present invention, a description of a general configuration and its operation not related to the features of the present invention is omitted for convenience of description.

The transmitting apparatus 100 receives image data for transmitting an image, encodes the image data into a layer signal according to the SVC scheme, applies a spreading code having a different length to each layer signal according to the importance of each layer signal, 200).

To this end, the transmitting apparatus 100 includes an SVC encoder 110, a spreading code generator 120, a spreader 130, and a transmission processing unit 140. Here, other components for processing the video signal may be further included between the SVC encoder 110 and the spreader 130, and between the spreader 130 and the transmission processor 140, It will be understood by those of ordinary skill in the art that a detailed description thereof will be omitted.

The SVC encoder 110 generates image data to be transmitted as an SVC bit stream and outputs the SVC bit stream. That is, the SVC encoder 110 converts the image data into a base layer signal, a first enhancement layer signal, a second enhancement layer signal, , And an n-th enhancement layer signal (n is a natural number of 3 or more). Here, the priority order of the image layer signals having different importance levels is that the base layer signal has the highest priority, and then the first enhancement layer signal, the second enhancement layer signal, , And the nth enhancement layer signal.

The spreading code generator 120 generates a spreading code. At this time, the spreading code generator 120 generates a spreading code according to length information according to a predetermined layer-by-layer signal. In the embodiment of the present invention, an orthogonal variable spreading factor (OVSF) code is used as a spreading code. Accordingly, the spreading code generator 120 generates the OVSF code according to the length information according to the layer-by-layer signal. In addition, the length information according to the predetermined layer-by-layer signal is set by the user at the time of the initial operation of the image transmission system 10. [ Alternatively, the length information according to the layer-by-layer signal may be adaptively reset according to layer-by-layer performance information fed back from the receiving apparatus 200 during operation of the image transmission system 10. This will be described in detail later.

For example, if the image transmission system 10 is set to use a spreading code of SF = 8, i.e., an OVSF code length of 8, the spreading code generator 120 basically generates a spreading code for the base layer signal An OVSF code having a code length of 8 is generated, and an OVSF code having a code length reduced by half according to its importance is generated for the remaining enhancement layer signals.

The spreader 130 receives a layer signal output from the SVC encoder 110, that is, a base layer signal, a first enhancement layer signal, a second enhancement layer signal, , And performs diffusion processing using the spreading codes generated in the spreading code generator 120, i.e., the OVSF code, for the nth enhancement layer signal. That is, the spreader 130 performs spreading processing on the base layer signal output from the SVC encoder 110 using the OVSF code for the base layer signal generated in the spread code generator 120, And outputs the first enhancement layer signal, which is output from the SVC encoder 110, by using the OVSF code for the first enhancement layer signal generated in the first enhancement layer 120. The remaining enhancement layer signals, i.e., the second enhancement layer signal, ... , And if there is an nth enhancement layer signal, the spreading process can be performed as described above.

The transmission processing unit 140 processes the layer signals diffused and output by the spreader 130 and transmits the layer signals to the receiving apparatus 200.

Although different processing is performed according to the video signal transmission method, the transmission processing unit 140 performs processing for transmission on each layer signals diffused and output by the spreader 130, IFFT (Inverse Fast Fourier Transform) processing, guard interval insertion processing, and the like are performed will be easily understood by those of ordinary skill in the art, and a detailed description thereof will be omitted here.

Next, the receiving apparatus 200 receives the image signal transmitted from the transmitting apparatus 100, despreads it by applying a different spreading code according to the importance of the layer signal, and outputs the image data generated by decoding according to the SVC scheme . The receiving apparatus 200 includes a cellular phone, a personal computer, a tablet computer, and the like.

To this end, the reception apparatus 200 includes a reception processing unit 210, a spreading code generator 220, a despreader 230, and an SVC decoder 240. Here, other components for processing a video signal may be further included between the reception processing unit 210 and the despreader 230, and between the despreader 230 and the SVC decoder 240, It will be understood by those of ordinary skill in the art that a detailed description thereof will be omitted.

The reception processing unit 210 performs reception processing on the video signal transmitted and received from the transmission apparatus 100 and outputs it as a reception video signal. The received video signal is composed of a layer signal. That is, a base layer signal, a first enhancement layer signal, a second enhancement layer signal, ... , And an nth enhancement layer signal.

Although the reception processing section 210 performs processing for receiving a video signal, other processing is performed according to the video signal transmission method, but processing such as a protection section removal processing, FFT processing, demodulation processing, and channel estimation processing is generally performed It will be understood by those of ordinary skill in the art that a detailed description thereof will be omitted here.

The spreading code generator 220 generates spreading codes, which are the same as those described in the spreading code generator 120 in the transmitting apparatus 100, and a detailed description thereof will be omitted here.

The despreader 230 despreads the layer signal output from the reception processor 210, that is, the base layer signal, the first enhancement layer signal, the second enhancement layer signal, , And outputs the n-th enhancement layer signal by despreading using the spreading code generated in the spreading code generator 220, that is, the OVSF code. That is, the despreader 230 despreads the base layer signal output from the reception processor 210 using the OVSF code for the base layer signal generated in the spreading code generator 220, And performs despread processing on the first enhancement layer signal output from the reception processing unit 210 using the OVSF code for the first enhancement layer signal generated by the code generator 220 and outputs the result. The remaining enhancement layer signals, i.e., the second enhancement layer signal, ... , And the n-th enhancement layer signal, the despread processing can be performed as described above.

The SVC decoder 240 demultiplexes the base layer signal, the first enhancement layer signal, the second enhancement layer signal, which is despread in the despreader 230, , And outputs the combined n-th enhancement layer signal as image data.

According to the image transmission system 10, the image data to be transmitted is encoded into a base layer signal and at least one enhancement layer signal according to the SVC scheme to allocate the longest OVSF code to the base layer signal having the highest priority, And the OVSF code, which is reduced by ½ of the OVSF code applied to the base layer signal, is sequentially allocated to the remaining enhancement layer signals. At this time, the OVSF codes allocated to the enhancement layer signals include all the codes that are not in the mother code relationship with the OVSF code allocated to the higher layer signal.

For example, as shown in FIG. 2, when a code having an OVSF code length of 8 is selected (1, 1, 1, 1, 1, 1, 1, The codes that can be assigned to the layer signals correspond to the codes allocated to the base layer signal and the remaining codes (indicated by light color) except for the codes having the mother code relationship (indicated by dark colors). Based on this, the number of available code sets according to the length of OVSF code is shown in [Table 1].

Figure 112015114147671-pat00001

Referring to Table 1, as shown in FIG. 2, SF = 8 is initially allocated to an OVSF code having a code length of 8 at the maximum. In the embodiment of the present invention, , So all eight code sets are available. However, for the next layer, the code should be allocated at SF = 4 with a code length of 1/2, but since one code has already been assigned to the base layer signal among eight codes of SF = 8, The code in the mother code relationship of the code assigned at SF = 8 is unusable, so that the number of code sets available at SF = 4 is three.

As for the OVSF codes having different maximum code lengths as described above, the number of usable code sets is determined according to the code length as shown in [Table 1].

As described above, in the image transmission system 10 according to the embodiment of the present invention, for different image quality requirements generated in an environment in which a plurality of receiving apparatuses 200 exist, By using a spreading code of a differential length, an efficient performance can be obtained in a limited transmission environment.

In addition, a communication network for efficient video signal transmission can be configured through the above.

In the above description, the spreading code generators 120 and 220 generate the spreading codes for each layer signal according to the length information according to the predetermined layer-by-layer signal. However, the technical scope of the present invention is not limited thereto The length of the spreading code allocated to each layer signal can be adaptively changed according to the performance information of each layer signal of the received video signal.

Hereinafter, the video transmission system 20 adaptively changing the length of the spreading code will be described.

FIG. 3 is a diagram illustrating a schematic configuration of a video transmission system according to another embodiment of the present invention.

3, the image transmission system 20 according to another exemplary embodiment of the present invention includes a transmission apparatus 300 and a reception apparatus 400. As shown in FIG. In FIG. 3, a description of a general configuration and an operation thereof, which are not related to features of the present invention, is omitted for convenience of description in the image transmission system 20 according to another embodiment of the present invention.

The transmitting apparatus 300 receives image data for transmitting an image, encodes the image data into a hierarchical signal according to the SVC scheme, applies a spreading code having a different length to each hierarchical signal according to the importance of the encoded hierarchical signal, 400). At this time, the transmission apparatus 300 can adaptively change the length of the spreading code allocated to each layer signal according to layer-by-layer channel information fed back from the receiving apparatus 400. The variable of the code length will be described later in detail.

The transmission apparatus 300 includes an SVC encoder 310, a code length setting unit 320, a spreading code generator 330, a spreader 340 and a transmission processing unit 350. The SVC encoder 310, the spreader 340 and the transmission processing unit 350 are identical in construction and operation to the SVC encoder 110, the spreader 130, and the transmission processing unit 140 described in FIG. 1, The description will be omitted. Other components for processing the video signal may be further included between the SVC encoder 310 and the spreader 340 and between the spreader 340 and the transmit processor 350, It will be understood by those of ordinary skill in the art that a detailed description thereof will be omitted.

Hereinafter, only the transmission apparatus 300 according to another embodiment of the present invention will be described with respect to components different from the transmission apparatus 100 described with reference to FIG.

The code length setting unit 320 receives layer-by-layer channel information fed back from the receiving apparatus 400. The layer-by-layer channel information is a layer-by-layer signal transmitted by the transmitting apparatus 300 to the receiving apparatus 400, that is, a base layer signal, a first enhancement layer signal, a second enhancement layer signal, And performance information of a channel corresponding to the nth enhancement layer signal.

The code length setting unit 320 basically sets a code length according to a priority order set in advance for each image layer. For example, a preset priority is a base layer having the highest priority, and in the following order, a first enhancement layer, a second enhancement layer, ... , And an nth enhancement layer. Therefore, the code length setting unit 320 sets a code length of a maximum length that can be set in the base layer, and sets a code length so as to be reduced by 1/2 in length for the next layer. For example, when a video signal is composed of a base layer signal, a first enhancement layer signal, a second enhancement layer signal, and a third enhancement layer signal, if SF = 32 code length is set in the base layer signal, SF = 16 for the second enhancement layer signal, SF = 8 for the second enhancement layer signal, and SF = 4 for the third enhancement layer signal.

As a result of setting the code length and generating and applying the OVSF code as described above, it is possible to know a layer having a poor channel state through the channel information received and measured by the receiving apparatus 400, and the channel state is reflected So that the code length can be varied and set. That is, a code length longer than a preset code length can be set for a signal of a layer whose channel condition is poor. For example, referring to Table 2, the channel state of each layer determined by the layer-by-layer channel information fed back from the receiving apparatus 400 is good for the base layer, the second enhancement layer, and the third enhancement layer, It can be seen that the channel state is not good for the first enhancement layer. Therefore, the code length set for the first enhancement layer is SF = 16, but can be set to a code length of SF = 32, which is a longer code length in consideration of the channel state.

Thereafter, when the code length of the first enhancement layer is restored by the increase of the code length by the layer-by-layer channel information fed back from the reception apparatus 400 and it is determined that the channel state of the first enhancement layer is good, That is, SF = 16 and is set.

hierarchy Channel status Code length (SF) Base layer G (good) 32 The first enhancement layer B (defective) 16 -> 32 Second enhancement layer G (good) 8 Third enhancement layer G (good) 4

The spreading code generator 330 generates a spreading code and applies the spreading code to the spreader 340, and generates a spreading code having a layered code length set by the code length setting unit 320.

The content of the spreading code generator 330 generating the spreading code is the same as that of the spreading code generator 120 described with reference to FIG. 1, so a detailed description thereof will be omitted.

Next, the receiving apparatus 400 receives the video signal transmitted from the transmitting apparatus 100, applies a spreading code having a different length to each layer signal according to the importance of the layer signal, despreads it, and decodes it according to the SVC technique And outputs the image data. At this time, the receiving apparatus 400 receives the layer-by-layer signal transmitted from the transmitting apparatus 300 through the layer-by-layer channel, performs channel estimation, and transmits channel information for each layer, ). The layer-by-layer channel information includes channel state information indicating a channel state of each layer as G (good), B (bad), etc. as described in the transmitter 300. [ The layer-by-layer channel information may be applied to the transmitter 300 if the code length applied to the layer-by-layer signal varies, and the layer-by-layer channel state information may be further segmented.

To this end, the receiving apparatus 400 includes a reception processing unit 410, a channel estimation unit 420, a code length setting unit 430, a spreading code generator 440, a despreader 450 and an SVC decoder 460 do. Here, the despreader 450 and the SVC decoder 460 are the same in construction and operation as the despreader 230 and the SVC decoder 240 described in FIG. 1, and a detailed description thereof will be omitted here. Other components for processing the video signal may be further included between the reception processor 410 and the despreader 450 and between the despreader 450 and the SVC decoder 460, It will be understood by those of ordinary skill in the art that a detailed description thereof will be omitted. In addition, the reception processing unit 410 performs the same configuration and operation as the reception processing unit 210 shown in FIG. 1 except for the configuration for performing channel estimation in the reception processing unit 210 shown in FIG.

Hereinafter, a receiving apparatus 400 according to another embodiment of the present invention will be described with respect to components different from the receiving apparatus 200 described with reference to FIG.

The channel estimator 420 estimates a channel signal output from the reception processor 410, that is, a base layer signal, a first enhancement layer signal, a second enhancement layer signal, N-th enhancement layer signals, and feeds back state information for each channel, which is obtained through channel estimation, to the transmitter 300 as channel information for each channel. At this time, the state information for each channel represents a channel state determined by comparing with the channel state for each layer determined by the previously received video signal. The contents of the channel estimation unit 420 for channel state information through channel estimation are well known, and a detailed description thereof will be omitted here.

The code length setting unit 430 has the same configuration and operation as the code length setting unit 320 in the transmitting apparatus 300 except that the code length setting unit 320 of the transmitting apparatus 300 transmits the code length The code length setting unit 430 of the receiving apparatus 400 directly receives the layer-by-layer channel information output from the channel estimating unit 420, Set the length.

The spreading code generator 440 is identical in configuration and operation to the spreading code generator 330 in the transmitting apparatus 300 to generate a spreading code having a code length per layer set by the code length setting unit 430 And therefore, a detailed description thereof will be omitted here.

Hereinafter, a method of adaptively adjusting the length of the spreading code according to another embodiment of the present invention will be described.

4 is a flow diagram of a method for adaptively adjusting the length of a spreading code according to another embodiment of the present invention. In this method, the reception apparatus 400 measures the channel state of each layer by channel estimation of the reception signal and feeds back to the transmission apparatus 300 as channel information per layer. Therefore, only the contents performed by the transmission apparatus 300 This will be described in detail.

4, the code length setting unit 320 of the transmitting apparatus 300 sets the code length for each layer as a basic code length according to the code length information set in advance at the beginning of the operation of the video transmission system 20 (S100 ). These basic code lengths include base layer, first enhancement layer, second enhancement layer, ... , And the length of the spreading code is set to a code length decreasing by 1/2 from the longest length as a priority of the nth enhancement layer. This has already been described with reference to Table 2, and a detailed description thereof will be omitted here.

Thereafter, the spreading code generator 330 generates a spreading code for each layer according to the basic code length set by the code length setting unit 320, and the spreader 340 generates spreading codes for each layer generated by the spreading code generator 330 The layer signals of the video signals to be transmitted are spread using a spreading code having a basic code length and transmitted to the receiving apparatus 400 (S120 and S130).

Accordingly, the receiving apparatus 400 receives the layer-by-layer video signal transmitted from the transmitting apparatus 300, estimates the channel, and feeds back the layer-by-layer channel information including the layer-by-layer channel information to the transmitting apparatus 300, 300) may receive layer-by-layer channel information fed back from the receiving apparatus 400 (S140).

In this manner, when the layer-by-layer channel information is received from the receiving apparatus 400, the code length setting unit 320 analyzes the layer-by-layer channel information to determine a channel state for each layer (S150) It is determined whether there is a layer in which the channel state is changed (S160).

If there is a layer having a changed channel state, the code length set for the layer is adjusted according to the changed channel state (S170). That is, the code length is increased or decreased. This will be described in detail later.

If it is determined that the transmission of the video signal in the video transmission system 20 is terminated (S180), the transmission of the video signal is repeated.

Hereinafter, a method of adjusting the code length according to the channel state change will be described.

FIG. 5 is a specific flowchart of a method of adjusting a code length per layer according to the channel state shown in FIG.

Referring to FIG. 5, it is determined whether the channel state of the layer whose channel state has changed is bad (S171).

If the channel state is deteriorated, the code length is increased to transmit a video signal in a better state through the layer (S172). At this time, the increase of the code length increases the code length to twice the length of the previously set code, as shown in [Table 2].

On the other hand, if the channel state is not deteriorated in step S171, it is determined whether the channel state is improved (S173).

If the channel state is improved, it is also possible to transmit a video signal in a more difficult state through the layer, thereby reducing the code length (S174). At this time, the decrease of the code length is to reduce the code length to 1/2 length of the previous code length.

Meanwhile, the code length may be increased or decreased according to the channel state of each layer as described above by setting the basic code length to a minimum length. That is, when the code length is set to the basic code length, it means that the code length is not reduced even if the channel state is improved. This is because the code length adjustment is performed only when the channel state of each layer temporarily deteriorates and becomes better.

As described above, in the image transmission system 20 according to another embodiment of the present invention, the length of the spreading code is adaptively changed according to the channel state of each layer while applying the differential spreading code length for each layer, Can be obtained.

In the above description, the receiving apparatus 400 measures channel information for each layer of the receiving channel and feeds back the channel information to the transmitting apparatus 300. When the transmitting apparatus 300 receives feedback information from the receiving apparatus 400, Only the contents of adjusting the code length of the spreading code applied to the layer-by-layer signal according to the layer-by-layer channel state are described, but the technical scope of the present invention is not limited thereto and can be reflected in various forms.

For example, in an environment where there are multiple receiving devices, i.e., multiple receiving terminals, the performance of video signals differs from terminal to terminal because the required performance is different for each terminal. Therefore, the transmitting apparatus 300 receives the information according to the type of the receiving terminal and can effectively transmit the image based on the information.

In this example, when there are a plurality of terminals requesting a high-performance video signal among the reception terminals, the transmission apparatus 300 may increase the length of the spreading code for each layer signal in order to satisfy the demands of a plurality of high- And in the opposite case, the length of the spreading code of the remaining layers excluding the base layer signal, which is the minimum information necessary for information transmission, may be reduced and the code length may be adjusted and applied. The configuration for applying this example will be easily understood by those skilled in the art based on the above description.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (18)

A scalable video coding (SVC) bitstream, wherein the SVC bitstream comprises a base layer signal to be transmitted and at least one enhancement layer signal, which is combined with the base layer signal and improves the quality of the video information, ≪ / RTI >
A spreading code generator for generating spreading codes according to preset code lengths of layers;
A spreader for spreading each layer signal of the SVC bit stream encoded and output by the encoder by applying a spreading code for each layer generated in the spreading code generator; And
A code length setting unit for adjusting a code length set for each layer according to a channel state of each layer fed back from the receiving apparatus,
Lt; / RTI >
The spreading code generator generates a spreading code for each layer according to a code length adjusted by the code length setting unit and provides the spreading code to the spreader
And a transmission unit for transmitting the transmission data. delete The method according to claim 1,
Wherein the code length setting unit increases a code length set for a layer determined to be worse than a previous channel state based on the channel state for each layer. The method of claim 3,
Wherein the control unit decreases the code length set for the layer when it is determined that the channel state is improved over the previous channel state by the layer-by-layer channel state for the layer set to increase the code length. The method according to claim 1,
Wherein the code length setting unit increases or decreases a code length of a spreading code set for each layer according to a request performance fed back from two or more receiving apparatuses. 6. The method of claim 5,
Wherein the code length setting unit reduces only the code length set for the remaining enhancement layers excluding the code length set for the base layer when the code length set for each layer is decreased according to the requested performance. A spreading code generator for generating spreading codes according to preset code lengths of layers;
An SVC bitstream transmitted from a transmitting apparatus, wherein the SVC bitstream is divided into a base layer signal to be transmitted and at least one enhancement layer signal, which is combined with the base layer signal and improves the quality of the moving picture information A despreader for despreading a signal by applying a spreading code for each layer generated in the spreading code generator;
A decoder for combining the SVC bitstream output from the despreader and outputting the combined image data;
A channel estimator for estimating a channel state of each layer using the video signal received from the transmitter and feeding back the estimated channel state to the transmitter; And
A code length setting unit for adjusting a code length set for each layer according to a channel state of each layer estimated by the channel estimating unit,
Lt; / RTI >
Wherein the spreading code generator generates a spreading code for each layer according to a code length adjusted by the code length setting unit and provides the spreading code to the despreader
. delete 8. The method of claim 7,
Wherein the channel estimation unit estimates a channel state of a currently received video signal by comparing the channel state of each layer estimated based on the previously received video signal. A method for a transmitter to adjust the length of a spreading code,
SVC bitstream, wherein the SVC bitstream is divided into a base layer signal to be transmitted and at least one enhancement layer signal that is combined with the base layer signal to improve the quality of the video information. Setting a code length to a basic code length;
Spreading the layer-by-layer signal using a spreading code generated for each layer according to the basic code length and transmitting the spreading signal to a receiving device;
Determining whether there is a layer whose channel state is changed based on the channel state information for each layer when the channel state information for each layer is fed back from the receiving apparatus;
Adjusting a code length for each layer by increasing or decreasing a code length for a layer whose channel state is changed when there is a layer whose channel state is changed; And
Spreading the layer-by-layer signal using a spreading code generated for each layer according to an adjusted layer-by-layer code length and transmitting the spread signal to the receiving device
/ RTI > 11. The method of claim 10,
Wherein the basic code length is the longest code length set for the base layer signal and the enhancement layer signal has a half length from the code length set in the base layer signal as the importance is lowered, Wherein the length of the spreading code length is reduced by a predetermined length. 11. The method of claim 10,
The step of adjusting the code length of each layer includes:
Determining whether a channel state for each layer is worse than a state for each layer;
Increasing a code length for a layer in which a channel state per layer is deteriorated when the channel state per layer is deteriorated; And
A step of setting a code length of the layer having a better channel state per layer by decreasing the code length
/ RTI > A scalable video coding (SVC) bitstream, wherein the SVC bitstream is composed of a base layer signal to be transmitted and at least one enhancement layer signal combined with the base layer signal, And a spreading code having a different length for each layer signal according to the importance of each encoded layer signal and transmitting the spreading code; And
A receiver for receiving image signals of the SVC bit stream transmitted from the transmitter and despreading the image data by applying a spreading code having a code length applied in each layer in the transmitter to perform SVC decoding,
/ RTI >
The receiving apparatus grasps the channel state of each layer through channel estimation of the received layer-by-layer signal, feeds back to the transmitting apparatus,
The transmitting apparatus generates a spreading code by increasing or decreasing the length of the spreading code for the layer whose channel state has changed compared to the channel state for each layer through the layered channel state fed back from the receiving apparatus
Wherein the video transmission system comprises: 14. The method of claim 13,
The transmitting apparatus includes:
An encoder for encoding the image data into the SVC bitstream;
A first spreading code generator for generating spreading codes according to preset code lengths of layers; And
A spreader for applying a spreading code for each layer generated in the first spreading code generator to each layer signal of the SVC bit stream encoded and output by the encoder,
The system comprising: 15. The method of claim 14,
The receiving apparatus includes:
A second spreading code generator for generating a spreading code according to a code length for each layer having a code length equal to a code length for each layer generated in the first spreading code generator;
A despreader for despreading the video signal of the SVC bitstream transmitted from the transmitter by applying a spreading code for each layer generated in the second spreading code generator; And
A decoder for combining the SVC bit stream output from the despreader and outputting the combined SVC bit stream as image data;
The system comprising: delete 16. The method according to claim 14 or 15,
The code length of each layer is set to a length of a longest code length in the base layer signal and a code length of the enhancement layer signal is reduced by 1/2 from the code length set in the base layer signal Wherein the video transmission system comprises: 18. The method of claim 17,
The spreading code is an Orthogonal Variable Spreading Factor (OVSF) code,
A spreading code applied to a layer signal having a low importance level is assigned to a spreading code applied to a layer signal having a high importance and a spreading code
Wherein the video transmission system comprises:
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000286823A (en) * 1999-03-03 2000-10-13 Sony Internatl Europ Gmbh Radio transmission method, radio transmission system and transmitter

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000286823A (en) * 1999-03-03 2000-10-13 Sony Internatl Europ Gmbh Radio transmission method, radio transmission system and transmitter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
N. Conci. Advanced techniques for scalable coding for video transmission over resource constrained networks. Ph.D Thesis, Int'l Doctrate School in Info. and Comm. Technologies. 2007. pp.1-113*

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