KR101652497B1 - System for Terrestrial 4K UHD, HD Convergence Broadcasting using Multiple-PLP and method therefor - Google Patents

Abstract

The present invention relates to a system for broadcasting 4K UHD and HD programs at the same time through a signal terrestrial television channel using an M-PLP multiplexing method and a method thereof and, more specifically, to a system for broadcasting 4K UHD and HD programs through a signal terrestrial television channel using an M-PLP multiplexing method capable of multiplexing and providing broadcast services of multiple classes within a single frame through the single terrestrial television channel and to a method thereof. According to the described above, the system for broadcasting the 4K UHD and HD programs through the signal terrestrial television channel using the M-PLP multiplexing method is able to multiplex and transmit 4K UHD and HD video data within the single frame by applying different channel codes and different modification constellations to the data in different classes while transmitting the 4K UHD and HD video data through a terrestrial television broadcast network. In addition, an effect of receiving 4K UHD or HD videos with a mobile terminal and a stationary receiving device is obtained.

Description

[0001] The present invention relates to a terrestrial single channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique,

The present invention relates to a terrestrial single channel fixed 4K UHD and HD convergence broadcasting system and method thereof using an M-PLP multiplexing technique, and more particularly, to a system and method for multiplexing a plurality of broadcasting services in a single frame through a single terrestrial channel Channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique for transmitting high-frequency signals, and a method thereof.

As the worldwide transition from analogue broadcasting to digital broadcasting is almost completed, the next-generation broadcasting standard for high-capacity broadcasting and broadcasting o communication convergence environments of UHDTV (Ultra High Definition TV) The need for research is increasing day by day. Fourteen organizations including ATSC (Advanced Television Systems Committee), DVB (Digital Video Broadcasting), EBU (European Broadcasting Union), NHK and ETRI (Electronics and Telecommunications Research Institute) To discuss the role of broadcasting based on broadband ecosystem, the characteristics of next-generation public broadcasting system, spectrum squeeze and future broadcasting system. In addition to the mobile communication technology in the trend of increasingly advanced digital broadcasting, digital DVB 2.0 system is used in Europe, ATSC 3.0 system is used in Europe, and ISDB (Japan) is used in Japan in order to preempt technology for advanced next- Integrated Services Digital Broadcasting (TMS) - TMS (Terrestrial mobile multi-media) system has already been developed, and it is necessary to research and develop equipment for source technology and new service in related future broadcasting technology in Korea. It is a situation.

According to a conventional method and apparatus for transmitting / receiving a data stream through a frame structure of a wireless broadcast system and a frame structure, a preamble section including fixed data items and constituent data items and one Comprising the steps of: configuring a frame to include a data section including a physical layer pipe (PLP), and transmitting the configured frame, wherein the configuration data items are associated with at least one PLP, And a preamble section of the frame is configured in consideration of the repetition length of the configuration data items.

Currently, Korea is providing a terrestrial digital HD broadcasting service using ATSC 8-VSB (Vestigial SideBand) system through a 6MHz bandwidth. In addition, a digital DAB (Digital Audio Broadcasting) transmission system QVGA (320x240 resolution) mobile broadcasting using DMB (Digital Multimedia Broadcasting) transmission system which modified Eureak-147 system. However, the ATSC 8-VSB system, which is a first-generation digital broadcasting system for the United States, has already been standardized in 1990 and it is difficult to achieve the required transmission rate for terrestrial UHDTV broadcasting using the current ATSC 8-VSB system . In addition, the terrestrial mobile DMB system has gained popularity due to its smooth reception performance in a high-speed channel environment. However, since the spread of a high-speed mobile communication system such as LTE became full, due to the low resolution problem of QVGA, (1280x720 resolution) mobile broadcasting based on mobile communications such as T-Mobile and Tving. In addition, in order to provide terrestrial HD broadcasting and mobile broadcasting in Korea, different systems are used for transmission through separate bandwidths. In the future, frequency conflicts between mobile communication companies and broadcasters are expected to deepen, And terrestrial broadcasting service using the system have a disadvantage in that they are inferior in frequency efficiency.

In this regard, it is necessary to study the method of transmitting terrestrial 4K UHD and high quality mobile broadcasting using one broadcast transmission system with high frequency efficiency in preparation for the coming Post-HD era. .

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a method and apparatus for transmitting 4K UHD and HD video data through a terrestrial broadcasting network by applying different channel coding rates and modulation constellation Channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique capable of multiplexing and transmitting within a frame, and a method thereof.

The present invention relates to an apparatus and method for decoding data in a PLP layer, the apparatus comprising: a layer unit for receiving first image data and second image data of different PLP layers and channel-coding the first and second image data at different coding rates; A frame builder for setting the first image data and the second image data together with the system additional information as a single transmission frame; And a transmitter for transmitting the single transmission frame in a single frequency band through OFDM symbol modulation through frequency axis interleaving.

Meanwhile, the terrestrial single channel fixed 4K UHD and HD convergence broadcasting method using the M-PLP multiplexing method includes: (a) receiving first and second image data of different PLP layers and performing channel coding at different coding rates; Performing cell and time axis interleaving on the data obtained by rotating the constellation of each image data to a predetermined phase; (b) setting the first image data and the second image data together with the system side information as a single transmission frame; And (c) transmitting the single transmission frame in a single frequency band through OFDM symbol modulation through frequency axis interleaving.

According to the above description, it is possible to transmit 4K UHD addition and HD video data through a terrestrial broadcasting network, and multiplex data of different layers in one frame by applying different channel coding rate and modulation constellation to each other, And a 4K UHD or HD image can be received in a stationary receiver.

1 is a diagram illustrating a configuration of a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to the present invention,
FIG. 2 is a conceptual diagram of a terrestrial 4K UHD & HD fusion broadcasting service through a single channel of a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention,
FIG. 3 is a diagram illustrating a structure of a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention,
FIG. 4 is a diagram illustrating a structure of a single transmission frame in a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention,
5 is an exemplary view showing the total number of subcarriers and effective subcarriers in a single frame according to the transmission parameter # 1,
FIG. 6 is a graph showing the 4K UHD & HD layer BER performance on the TU6 & AWGN channel according to the first transmission parameter in Table 4. FIG. 4K UHD & HD layer BER performance, and FIG. 8 is a graph illustrating the 4K UHD & HD layer BER performance in the TU6 & AWGN channel according to the third transmission parameter in Table 4. FIG.
9 is a graph showing 4K UHD & HD layer BER performance in TU6 & AWGN channel according to 1st transmission parameter in Table 7. FIG. 10 is a graph illustrating performance of 4K UHD & HD layer BER in TU6 & AWGN channel according to 2nd transmission parameter in Table 7. FIG. FIG. 11 is a graph showing the 4K UHD & HD layer BER performance in the TU6 & AWGN channel according to the third transmission parameter in Table 7, and FIG. 12 is a graph showing the BER performance in the 4K UHD & FIG. 13 is a graph showing the 4K UHD & HD layer BER performance on the TU6 & AWGN channel according to the fifth transmission parameter in Table 7. FIG. 13 is a graph showing the 4K UHD & HD layer BER performance on the TU6 & Fig.
FIG. 14 is an overall flowchart illustrating a method using a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

The terrestrial single channel fixed 4K UHD and HD fusion broadcasting transmission system using the M-PLP multiplexing technique according to the present invention transmits 4K UHD addition and HD video data through a terrestrial broadcasting network, And modulation constellation can be applied to multiplex and transmit in one frame, and 4K UHD or HD video can be received in mobile and stationary receiver.

The terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using the M-PLP multiplexing technique according to an embodiment of the present invention receives first image data and second image data of different PLP layers, A layer unit for channel-coding and performing time-axis interleaving of data in which the constellation is rotated in a predetermined phase; A frame builder for setting the first image data and the second image data together with the system additional information as a single transmission frame; And a transmitter for transmitting the single transmission frame in a single frequency band through OFDM symbol modulation through frequency axis interleaving.

A receiver for performing synchronization recovery and channel equalization on the signal received through the single frequency band at the OFDM symbol level and performing decoding through frequency inverse interleaving; And a reproducing unit for reproducing the 4K UHD image by combining the data of the two layers decoded by the receiving unit and reproducing the HD image by the decoded HD data. Here, the first image data and the second image data may be 4K UHD image data and 4K UHD image data compressed by SHVC (Scalable HEVC), respectively.

Wherein the layer unit comprises: an FEC encoder module for channel encoding 4K UHD additional image data and HD basic image data; A modulation module for modulating the 4K UHD additional image data into 256QAM, encoding the 4K UHD additional image data with a 4/5 code rate, modulating the HD basic image data into 16QAM, and encoding the 4K UHD additional image data with a 3/4 code rate; A rotation constellation modulating and cyclic Q delay module for rotating the rotation constellation in a predetermined phase according to the QAM modulation; And a cell and a time axis interleaver module for performing cell and time axis interleaving of each data mapped in the rotational phase. In the single transmission frame structure, 60% of the subcarriers are used for data transmission of the 4K UHD sublayer and 40% of the subcarriers are used for transmission of data of the HD base layer.

Meanwhile, the terrestrial single channel fixed 4K UHD and HD fusion broadcasting method using M-PLP multiplexing technique is as follows.

(a) receiving first image data and second image data of different PLP layers and channel-coding the first image data and the second image data at different coding rates, respectively, and rotating the constellation of the respective image data in a predetermined phase, ; (b) setting the first image data and the second image data together with the system side information as a single transmission frame; And (c) transmitting the single transmission frame in a single frequency band through OFDM symbol modulation through frequency axis interleaving.

After step (c), (d) performing synchronization recovery and channel equalization on a signal received through a single frequency band at an OFDM symbol level and decoding through frequency inverse interleaving; And (e) reproducing the 4K UHD image by combining the decoded first and second image data, and reproducing the HD image with the decoded second image data. The first image data and the second image data according to the present embodiment are 4K UHD additional image data and 4K UHD raw image data that are image-compressed by SHVC (Scalable HEVC), respectively.

The step (a) includes the steps of (a-1) channel-coding 4K UHD additional image data and HD basic image data; (a-2) modulating the 4K UHD additional image data into 256QAM, encoding the 4K UHD additional image data with a 4/5 coding rate, modulating the HD basic image data into 16QAM, and encoding the 4K UHD additional image data with a coding rate of 3/4; (a-3) a rotational constellation-modulated and cyclic Q-delaying step of rotating the rotational constellation in a predetermined phase according to each QAM modulation; And (a-4) performing cell and time-axis interleaving of each data mapped in the rotatable phase.

In the single transmission frame structure, 60% of the subcarriers are used for data transmission of the 4K UHD sublayer and 40% of the subcarriers are used for transmission of data of the HD base layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a configuration of a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to the present invention. As shown in these drawings, the image compression unit 110, the layer unit 120, the frame builder unit 130, the transmission unit 140, the reception unit 150, and the playback unit 160 have.

The image compressing unit 110 compresses the 4K UHD image using the SHVC image compression technique to obtain the 4K UHD additional image data and the HD basic image data.

The layer unit 120 receives the 4K UHD additional image data as the first image data and the HD basic image data as the second image data and performs channel coding on the 4K UHD additional image data and the HD basic image data at different coding rates, Axis interleaving.

The layer unit 120 includes an FEC encoder module 121, a modulation module (256QAM Modulation & Bit Itrv) 122, a rotation constellation rotation and cyclic Q- delay 123, a cell and time interleaver module 124, and the like.

The FEC encoder module 121 is configured to channel-encode the 4K UHD additional image data and the HD basic image data. The FEC encoder 121 adds bits for error detection and correction to transmit the bits. The receiver checks the error and requests retransmission of data Or to detect and correct errors on its own. That is, a parity bit may be added or a CRC (Cyclic Redundancy Check) code may be added to the receiving side by a method of self-error detection correction.

The modulation module 122 modulates the 4K UHD additional image data into 256QAM, encodes it with a code rate of 4/5, modulates the HD basic image data into 16QAM, and encodes it with a code rate of 3/4. For example, the terrestrial single channel fixed 4K UHD and HD convergence broadcasting system using the M-PLP multiplexing technique according to the present embodiment modulates SD (Standard Definition) broadcast data to 16QAM with PLP1, The PLP3 modulates the 3D TV broadcast data into 256QAM, codes it at a code rate of 4/5, and multiplexes and transmits the Multiple-PLP data in one single frame. The SD broadcast data transmitted to the PLP1 layer is more robust to the channel than the 3D TV broadcast data transmitted to the PLP3. Therefore, each receiver can selectively receive and receive data of the PLP layer according to the channel condition. In this case, the size of the FFT and the CP (Cyclic Prefix) of the OFDM symbols in a single frame does not change, and the P1 & P2 OFDM symbols are used to transmit additional information such as system information and additional information.

The rotation constellation modulation and cyclic Q delay module 123 is configured to be robust against a frequency selective multi-path channel. The constellation is rotated by a certain phase according to each mode and transmitted, (For example, 16200 cells = 64800/4 (16QAM))).

The cell and time-base interleaver module 124 is a configuration for performing cell and time-axis interleaving of each data mapped by the modulation constellation.

The frame builder 130 configures the two layer data of the 4K UHD additional image data and the HD basic image data together with the additional information related to the system into a single transmission frame.

4, the FFT size is 8,192, and 60% of the total subcarriers are used for data transmission of the 4K UHD sublayer and 40% of the total subcarriers are used for transmission of data of the HD base layer A single transmission frame is shown. The P1 symbol for transmitting information to the system is composed of 2048 subcarriers regardless of the FFT size. When the FFT size is 8,192, the number of P2 symbols is two. Thereafter, there are data symbols as many as the number of data symbols used for data transmission.

The size of the FFT and guard interval of the OFDM symbols in the single frame are not changed, and the P1 & P2 OFDM symbols are used to transmit additional information such as system information.

Each block shown in FIG. 4 represents an OFDM symbol, and CP (Cyclic Prefix), which is a guard interval, is omitted for convenience, but is added to all OFDM symbols except for a P1 symbol in actual transmission. The transmission frame consists of P1, P2, and data symbols. The P1 symbol exists at the beginning of each transmission frame and has a length of 2048 X T (Elementary Period) regardless of the FFT size. After the P1 symbol, there are P2 symbols for transmitting the system information. As shown in Table 1, it depends on the number of P2 symbols (Np2) according to the FFT size and is 2 when the FFT size is 8192. Thereafter, OFDM symbols corresponding to the number of data OFDM symbols (Ldata) that can be set according to the transmission parameter are configured. At this time, the number of effective subcarriers (Cdata) capable of transmitting actual data for one OFDM symbol differs depending on the combination of the FFT size and the Scattered pilot pattern, The scattered pilot pattern is selected according to the combination of the FFT size and the guard interval as shown in Table 3. The PLP1 data can be transmitted using 40% of the total effective sub-carriers thus determined and the PLP3 data can be transmitted using 60%.

[Table 1] Np2 according to FFT size

[Table 2] Number of effective subcarriers per OFDM symbol according to FFT size and pilot pattern (Cdata)

[Table 3]

The transmission unit 140 transmits a single transmission frame of the frame builder through a single frequency band by performing OFDM symbol modulation with a single FFT and a guard interval size through frequency axis interleaving.

The receiver 150 performs synchronization recovery and channel equalization on a signal received through a single frequency band channel at an OFDM symbol level, performs frequency inverse interleaving, separates the signals into respective layers, and then performs decoding on each layer to be.

The reproducing unit 160 may be configured to reproduce an image using two layers of data decoded through the receiving unit, and may include a fixed receiver and a mobile receiver. At this time, the fixed receiver reproduces the 4K UHD image using both decoded data of the two layers, and the mobile receiver reproduces the HD image using only the decoded HD data.

As a reference, the HEVC (High Efficiency Video Coding) technique is the next generation technology after the H.264 technique, which is the latest image compression technology, and the standard is currently under development and aims to improve the compression ratio by 50% compared with the maximum H.264 technique. The HEVC image compression technology is an image compression technology to cope with ultra-high resolution & super high image quality in preparation for the upcoming UHD TV broadcasting era. It has a wide range of resolution, color depth, lossless codec, and scalable video coding technique. .

Among them, the Scalable HEVC (SHVC) technique, which is a scalable video coding technique, focuses on minimizing the implementation complexity in order to solve the problem that the scalable video coding technique has a high complexity in the existing H.264 compression technique.

Two kinds of video data can be obtained when compressing UHD original video by SHVC technique. One is the additional UHD added video data, and the other is HD existing video data. HD basic video data can reproduce full HD video when using SHVC decoding, but can not reproduce UHD video using only additional UHD video data. Full UHD video can be reproduced only by using both additional UHD video data and HD video data compressed by SHVC.

FIG. 2 is a conceptual diagram of a terrestrial 4K UHD & HD fusion broadcasting service through a single channel of a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention. As shown in this figure, an 8K UHD image is compressed by an SHVC image compression technique, and an 8K UHD image, a 4K UHD image, and HD image data are acquired. After transmitting the 4K UHD & HD video data through the terrestrial broadcasting network using the single convergence broadcasting system, the stationary receiver receives both the 4K UHD addition and the HD data to reproduce the 4K UHD image, And reproduces the HD video. In addition, in a stationary receiver connected to a communication network, 8K UHD side information can be received through a communication network and combined with 4K UHD and HD information received through a broadcasting network to reproduce an 8K UHD image.

In the present embodiment, the 4K UHD image is compressed by the SHVC image compression technique, and the 4K UHD image and HD image data are acquired. After transmitting the 4K UHD & HD video data through the terrestrial broadcasting network using the single convergence broadcasting system, the stationary receiver receives both the 4K UHD addition and the HD data to reproduce the 4K UHD image, And reproduces the HD video. Also, in a stationary receiver connected to a communication network, the 4K UHD side information can be received through the communication network and combined with the 4K UHD and HD information received through the broadcasting network to reproduce the 4K UHD image. In the present invention, 4K UHD and HD video data can be transmitted through a broadcasting network and 4K UHD or HD video can be received from a mobile & stationary receiver.

In order to verify the possibility of terrestrial 4K UHD & HD convergence broadcasting service, it is necessary to analyze data transmission rate using SHVC image compression technology and verify whether transmission is possible through current terrestrial bandwidth. When compressing a worst-case single 4K UHD original image using a real-time real-time HEVC image encoder, a data rate of up to 25 Mbps can be achieved. When compressing a worst-case single HD original image, Of data transmission rate. In contrast, when 4K UHD original image is compressed by SHVC technology, the compressed HD basic image data rate is the same, while the 4K UHD additional image data requires a data rate of 21.25 Mbps. This is because HEVC technology compresses a single 4K UHD original image The data transfer rate can be reduced by up to 16.5%, and on average 15%.

In other words, for terrestrial 4K UHD & HD convergence broadcasting over a single channel, it is expected that the 4K UHD additional data of different layers needs a data rate of 21.25 Mbps and the HD basic data requires a data rate of 7Mbps. If the performance of the real-time HEVC image encoder is improved or the image is transmitted using the non real-time encoder, the required data transmission rate is expected to be lowered.

3 is a diagram illustrating a structure of a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention. As shown in this figure, the 4K UHD additional image data and the HD basic image data, which are two types of image data obtained through the SHVC image compression technique, are channel-encoded at different coding rates and mapped to different modulation constellations, Time-axis interleaving. Thereafter, the two layers of data are composed of a single transmission frame together with additional information related to the system using the Multiple-PLP technique, and the structure of a single transmission frame is shown in FIG.

4 is a diagram illustrating a structure of a single transmission frame in a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention.

As shown in FIG. 4, a single transmission frame is composed of a P1 symbol having 2048 subcarriers, a P2 symbol composed of a plurality of subcarriers according to the FFT size, and subcarriers transmitting two layers of data.

Two layers of data are composed of a single transmission frame, then subjected to frequency-axis interleaving and then transmitted through a single frequency band with OFDM symbol modulation. And performs synchronization recovery and channel equalization at the OFDM symbol level with respect to the signal received through the channel. Then, after frequency inverse interleaving is performed, each layer is separated and then decoded for each layer. The stationary receiver reproduces the 4K UHD image using both decoded data of the two layers, and the mobile receiver reproduces the HD image using only the decoded HD data.

On the other hand, optimal transmission parameters are derived and simulated results are shown in the 4K UHD and HD convergence broadcasting system using terrestrial single channel using M-PLP multiplexing scheme.

Based on the data transmission requirement after SHVC compression, we derive optimal transmission parameters for transmitting two layers of data over 6MHz bandwidth and verify the reception performance under various channels.

At this time, the data rate of each layer is determined by the transmission mode (modulation constellation, code rate, FFT & guard interval size, pilot insertion mode, etc.), the number of all subcarriers according to the transmission mode, the number of effective subcarriers, And the transmission parameters derived according to the following frame configuration conditions in the 6 MHz bandwidth are shown in Table 4.

[Table 4] Transmission parameters derived from 6 MHz bandwidth (4K UHD layer: 256QAM modulation, HD layer: 16QAM modulation)

* 4K UHD layer Data charge ratio in single frame: 60%

* HD layer Single data frame charge ratio: 40%

* Maximum length of single frame: 250 ms

* Elementary Period T for 6 MHz Bandwidth: 7/48 us

The 4K UHD layer and the HD layer each take into consideration all the conditions. However, the 4K UHD layer requires the 256 QAM modulation method and the HD layer uses the 16QAM modulation method to achieve the required data transmission rate. In addition, 16K and 32K FFT sizes are excluded in consideration of the mobile environment in which data in the HD layer is transmitted. As a result of this transmission parameter, it can be seen that the coding rate of 4K UHD & HD layer is rather high and the FFT size is 8192 due to the limitation of 6MHz bandwidth, and the size of the guard interval is limited to 1/32. It can be expected that the reception performance may be weak relative to the environment of the time-varying channel when the derived transmission parameter is used.

The number of all subcarriers and effective subcarriers in a single transmission frame is determined according to the FFT size, the Cyclic Prefix (CP) size, the number of OFDM symbols in the frame, and the pilot mode. At this time, only effective subcarriers of all subcarriers are used for actual data transmission, and the remaining subcarriers are used for transmission of pilot, system information, and the like.

FIG. 5 is a diagram illustrating the number of all subcarriers and valid subcarriers in a single frame according to the transmission parameter # 1. One single frame is composed of a P1 symbol, a P2 symbol, and a data symbol.

At this time, the P1 symbol and the P2 symbol are used for transmitting the system parameters and the system parameters (FFT size, CP size, number of OFDM symbols in the frame, etc.). The P1 symbols are composed of 2048 subcarriers regardless of the FFT size, and the FFT size is 8192 and the number of P2 symbols is two. Since the size of 1/32 of the guard interval CP is used and the number of OFDM symbols in a single frame is set to 200, the total number of subcarriers in a single frame is 1,669,750 as shown in FIG. Of the 8192 subcarriers per OFDM symbol, the number of effective subcarriers in a single frame is 6,788 x 200 = 1,357,600 since 6,788 subcarriers are used for actual data transmission. Since the Elementary Period T, which is the subcarrier transmission time corresponding to one sample, is 7/48 us in the 6 MHz bandwidth, the time during which a single frame is transmitted is equal to (1).

[Equation 1]

It can be seen from equation (1) that 1,357,600 effective subcarriers are transmitted during 243.51 ms, and the number of effective subcarriers transmitted for 1 second can be obtained as follows.

&Quot; (2) "

From equation (2), it can be seen that about 5,387,987 valid subcarriers can be transmitted over one second. Based on this, the ratio of effective subcarriers used in the 4K UHD layer is 60%, the modulation constellation is 256 QAM (8 bits are transmitted on one effective subcarrier)

Since the channel coding rate is 4/5, the data rate of the 4K UHD layer is calculated as follows.

&Quot; (3) "

In addition, since the effective subcarrier used in the HD layer is 40%, the modulation constellation is 16 QAM (transmitting 4 bits for one effective subcarrier), and the channel coding rate is 4/5, the data transmission rate of the HD layer is calculated as follows same.

&Quot; (4) "

* Channel environment: AWGN, TU-6 channel

* Channel Estimation Technique Using Pilot Symbols: Least-Square Technique

* Frequency axis Channel interpolation method: Cubic-Spline interpolation method (Number of pilot symbols used for interpolation: 12)

* Time axis channel interpolation method: Linear interpolation method

* Time axis interleaving length of 4K UHD layer: 113 FEC (Forward Error Correction) channel code frame

* Time-axis interleaving length of HD layer: 35 FEC (Forward Error Correction) channel code frame

* Center frequency: 476 MHz (Digital TV channel frequency 14)

FIG. 6 is a graph showing the 4K UHD & HD layer BER performance on the TU6 & AWGN channel according to the first transmission parameter in Table 4. FIG. 4K UHD & HD layer BER performance, and FIG. 8 is a graph illustrating the 4K UHD & HD layer BER performance in the TU6 & AWGN channel according to the third transmission parameter in Table 4. FIG.

The bit error rate (BER) performance of the receiver under the TU-6 channel with 40Km / h and 60Km / h in the 4K UHD layer and 70Km / h and 110Km / h in the HD layer according to the transmission parameters 1 ~ 3 As a graph, it can be seen that the 4K UHD layer shows a threshold of visibility (TOV) at 26.6 ~ 28.6 dB at a reception rate of 40 km / h and 30.8 ~ 41.8 dB at a reception rate of 60 km / h. The TOV indicates a reception performance of about 10 ^-6 or less and a limit performance in which a received image is smoothly reproduced. Since it requires a TOV of 26 dB or more in all transmission modes, it is considered impossible to receive in mobile situations. However, since the 4K UHD layer assumes reception in a stationary receiver, it is considered that the TOV is not so high compared to the AWGN channel in a static channel environment.

In the case of the HD layer, which should consider the performance of the TU-6 channel first, the channel coding rate is 15.6 dB (70 km / h) and 20.3 dB (140 km / h) in transmission parameters 1 & h), it is believed that it will show smooth reception performance in a mobile environment up to a receiving speed of 140 km / h. However, it is difficult to achieve a good reception performance at a reception speed of 140 km / h or more. In case of the transmission parameter 3, the guard interval is increased compared to 1 & 2, The bandwidth of 8MHz is allocated to terrestrial channels in Europe, and now, the frequency bandwidth is expanded between government, broadcasters, and mobile operators. There is ongoing discussion about this. Considering these points and trying to overcome the performance degradation due to the limitation of 6 MHz bandwidth, we tried to derive the transmission parameters by assuming the frequency bandwidth to 8 MHz as the transmission parameter was derived at 6 MHz. The transmission parameters derived from the 8 MHz bandwidth are shown in Table 7.

[Table 5] Derived transmission parameters in the 6 MHz bandwidth (4K UHD layer: 256 QAM modulation, HD layer: 16 QAM modulation)

[Table 6] Threshold of Visibility (TOV) performance according to transmission parameters derived from 6 MHz bandwidth

* 4K UHD layer Data charge ratio in single frame: 60%

* HD layer Single data frame charge ratio: 40%

* Maximum length of single frame: 250 ms

* Elementary Period T for 8 MHz Bandwidth: 7/64 us

4K UHD and HD layers, all the conditions are considered. However, as in 6MHz, the 4K UHD layer requires 256 QAM modulation and the HD layer requires 16QAM modulation to achieve the required data rate. Unlike the case of the 6 MHz bandwidth, the coding rate of the HD layer is limited to a maximum of 3/4, and the pilot mode is also excluded from PP4, 5, 6 and 7. And we measured the transmission and reception performance under the simulated environment using the derived optimal transmission parameters.

[Table 7] Derived transmission parameters in 8 MHz bandwidth (4K UHD layer: 256 QAM modulation, HD layer: 16 QAM modulation)

[Table 8]

9 is a graph showing 4K UHD & HD layer BER performance in TU6 & AWGN channel according to 1st transmission parameter in Table 7. FIG. 10 is a graph illustrating performance of 4K UHD & HD layer BER in TU6 & AWGN channel according to 2nd transmission parameter in Table 7. FIG. FIG. 11 is a graph showing the 4K UHD & HD layer BER performance in the TU6 & AWGN channel according to the third transmission parameter in Table 7, and FIG. 12 is a graph showing the BER performance in the 4K UHD & FIG. 13 is a graph showing the 4K UHD & HD layer BER performance on the TU6 & AWGN channel according to the fifth transmission parameter in Table 7. FIG. 13 is a graph showing the 4K UHD & HD layer BER performance on the TU6 & Fig.

Figure 6 shows performance under TU-6 channel with receiver speeds of 70Km / h, 140Km / h and 210Km / h according to transmission parameters 1 ~ 5. It can be seen that when using all the transmission parameters derived from the 8 MHz bandwidth, the TOV of 24.3 dB to 28.1 dB for the 4K UHD layer and the TOV of 12.8 dB to 16.0 dB for the HD layer are shown under the TU-6 channel . This enables smooth reception of 4K UHD layer data in a static channel environment and smooth reception of HD layer data in a very fast mobile environment with a receiving speed of up to 210 Km / h. What is unusual is that the reception performance of transmission parameters 1 and 2 is not significantly different, which means that reception performance is very low due to the FFT size of 1024 and 2048 at a reception rate of up to 210 km / h. Also, we confirmed that we can obtain better performance in mobile environment by reducing the size of the guard interval and increasing the channel coding rate through the results of transmission parameters 2, 3, 4 and 5. Finally, when the FFT size is sufficiently small, the performance at a mobile environment (reception rate: 210 Km / h) in which the channel situation changes very rapidly generally occurs at a channel condition (reception rate: 70 Km / h) It can be confirmed that it is better than the reception performance.

Meanwhile, a method using a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using the M-PLP multiplexing method will be described with reference to FIG.

FIG. 14 is an overall flowchart illustrating a method using a terrestrial single channel fixed 4K UHD and HD fusion broadcasting system using an M-PLP multiplexing technique according to an embodiment of the present invention.

(A) receiving first image data and second image data of different PLP layers and channel-coding the first and second image data, respectively, at different coding rates, and converting the constellation of each image data into a predetermined phase, Performing axial interleaving; (b) setting the first image data and the second image data together with the system side information as a single transmission frame; And (c) transmitting the single transmission frame in a single frequency band through OFDM symbol modulation through frequency axis interleaving.

After step (c), (d) performing synchronization recovery and channel equalization on a signal received through a single frequency band at an OFDM symbol level and decoding through frequency inverse interleaving; And (e) reproducing the 4K UHD image by combining the decoded first and second image data, and reproducing the HD image with the decoded second image data. The first image data and the second image data according to the present embodiment are 4K UHD additional image data and 4K UHD raw image data that are image-compressed by SHVC (Scalable HEVC), respectively.

The step (a) includes the steps of (a-1) channel-encoding the 4K UHD additional image data, which is the first image data, and the HD basic image data, which is the second image data; (a-2) modulating the 4K UHD additional image data into 256QAM, encoding the 4K UHD additional image data with a 4/5 coding rate, modulating the HD basic image data into 16QAM, and encoding the 4K UHD additional image data with a coding rate of 3/4; (a-3) a rotational constellation-modulated and cyclic Q-delaying step of rotating the rotational constellation in a predetermined phase according to each QAM modulation; And (a-4) performing cell and time-axis interleaving of each data mapped in the rotatable phase.

In the single transmission frame structure, 60% of the subcarriers are used for data transmission of the 4K UHD sublayer and 40% of the subcarriers are used for transmission of data of the HD base layer.

In the Mutiple-PLP transmission scheme considered in the embodiment of the present invention, data of different layers can be transmitted through one frame by applying different channel coding rates and modulation constellations, while the sizes of OFDM symbols in a frame, The size of the FFT & guard interval of the 4K UHD layer data assuming the stationary receiver and the size of the FFT & guard interval of the data of the HD layer assuming the mobile receiver do not need to be the same. On the contrary, it is considered that the FFT size of the 4K UHD layer data is increased, the guard interval is reduced, the FFT size of the HD layer data is as small as possible, and the size of the guard interval is enlarged.

110: image compression unit 120:
121: FEC encoder module 122: modulation module
123: Rotational Constellation Modulation and Cyclic Q Delay Module
124: cell and time-base interleaver module 130: frame builder unit
140: Transmitting unit 150: Receiving unit
160:

Claims (10)

The first and second image data and the second image data of the different PLP layers are received and channel-coded at different coding rates. Data obtained by rotating the modulation constellation of the first and second image data by a predetermined phase is stored in the cell and time A layer unit for performing axial interleaving;
A frame builder for setting two-layer data of the first image data and the second image data together with system additional information as a single transmission frame; And
And a transmitter for transmitting the single transmission frame in a single frequency band through OFDM symbol modulation through frequency axis interleaving
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique. The method according to claim 1,
A receiver for performing synchronization recovery and channel equalization on the signal received through the single frequency band at the OFDM symbol level and performing decoding through frequency inverse interleaving; And
And a reproducing unit for reproducing the 4K UHD image by combining the two layers of data decoded by the receiving unit and reproducing the HD image by the decoded HD data,
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique. The method according to claim 1,
Wherein the first image data and the second image data are 4K UHD image data and 4K UHD image data compressed by SHVC (Scalable HEVC), respectively,
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique. The method according to claim 1,
The layer unit includes:
An FEC encoder module for channel coding 4K UHD additional image data and HD basic image data;
A modulation module for modulating the 4K UHD additional image data into 256QAM, encoding the 4K UHD additional image data with a 4/5 code rate, modulating the HD basic image data into 16QAM, and encoding the 4K UHD additional image data with a 3/4 code rate;
A rotation constellation modulating and cyclic Q delay module for rotating the rotation constellation in a predetermined phase according to the QAM modulation; And
And a cell and a time-base interleaver module for performing cell and time-axis interleaving of each data mapped in the rotatable phase
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique. The method according to claim 1,
The single transmission frame structure is characterized in that 60% of subcarriers are used for data transmission of a 4K UHD sublayer and 40% of the subcarriers are used for transmission of data of an HD base layer
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting system using M-PLP multiplexing technique. (a) receiving first image data and second image data of different PLP layers and channel-coding the first image data and the second image data at different coding rates, respectively, and rotating the constellation of the respective image data in a predetermined phase, ;
(b) setting two-layer data of the first image data and the second image data together with the system side information as a single transmission frame; And
(c) transmitting the single transmission frame in a single frequency band through OFDM symbol modulation through frequency axis interleaving
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting method using M-PLP multiplexing technique. The method according to claim 6,
After the step (c)
(d) performing synchronization recovery and channel equalization on a signal received through a single frequency band at an OFDM symbol level, and performing decoding through frequency inverse interleaving; And
(e) combining the decoded first and second image data to reproduce a 4K UHD image, and reproducing the HD image with the decoded second image data,
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting method using M-PLP multiplexing technique. The method according to claim 6,
Wherein the first image data and the second image data are 4K UHD image data and 4K UHD image data compressed by SHVC (Scalable HEVC), respectively,
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting method using M-PLP multiplexing technique. The method according to claim 6,
In the step (a)
(a-1) channel encoding 4K UHD additional image data and HD basic image data;
(a-2) modulating the 4K UHD additional image data into 256QAM, encoding the 4K UHD additional image data with a 4/5 coding rate, modulating the HD basic image data into 16QAM, and encoding the 4K UHD additional image data with a coding rate of 3/4;
(a-3) a rotational constellation-modulated and cyclic Q-delaying step of rotating the rotational constellation in a predetermined phase according to each QAM modulation; And
(a-4) performing cell and time-axis interleaving of the respective data mapped in the rotatable phase
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting method using M-PLP multiplexing technique. The method according to claim 6,
The single transmission frame structure is characterized in that 60% of subcarriers are used for data transmission of a 4K UHD sublayer and 40% of the subcarriers are used for transmission of data of an HD base layer
Terrestrial single channel fixed 4K UHD and HD convergence broadcasting method using M-PLP multiplexing technique.

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