KR20100021381A - Apparatus for transmitting and receiving digital multimedia broadcasting and method thereof - Google Patents

Abstract

PURPOSE: An apparatus for transmitting and receiving digital multimedia broadcasting and a method thereof are provided to change the modulation system of the enhancement layer stream according to the broadcasting environment. CONSTITUTION: The base layer processing unit(103) outputs the base layer stream. The enhancement layer processing unit(104) outputs the enhancement layer stream. The transmission unit(105) modulates the enhancement layer stream among the first and second layer modulation mode based on one layer modulation mode. The transmission unit is proceed the mapping of the symbol of the enhancement layer stream based on the symbol location of the base layer stream. The transmission unit is created the transfer frame. The different modulation system is used to the first and second layer modulation mode.

Description

Apparatus for Transmitting and Receiving Digital Multimedia Broadcasting and Method Thereof}

The present invention relates to an apparatus and method for transmitting and receiving digital multimedia broadcasting.

The present invention is derived from a study conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy [Task Management Number: 2006-S-017-03, Task name: Development of terrestrial DMB transmission advancement technology].

In order to increase the transmission capacity, the digital multimedia broadcasting transmission apparatus hierarchically applies an enhancement layer signal for increasing the transmission capacity to a base layer signal for transmitting a basic digital multimedia broadcasting service and transmits it to the reception apparatus.

However, there is a problem that such an enhancement layer signal is generated in the same manner regardless of the digital multimedia broadcasting network construction environment, service requirements, and reception performance according to the moving speed of the receiving apparatus.

An object of the present invention is to provide an apparatus and method for transmitting and receiving digital multimedia broadcasting which can change a modulation scheme of an enhancement layer stream according to a broadcasting environment.

In accordance with another aspect of the present invention, an apparatus for transmitting digital multimedia broadcasting includes: a base layer processor configured to output a base layer stream; An enhancement layer processor for outputting an enhancement layer stream; And modulating the enhancement layer stream based on one of the first and second layer modulation modes using different modulation schemes, and converting the symbols of the modulated enhancement layer stream based on the symbol positions of the base layer stream. It includes a transmitter for mapping to generate a transmission frame.

According to another aspect of the present invention, a method for transmitting a digital multimedia broadcasting by a digital multimedia broadcasting transmitting apparatus includes: outputting a base layer stream and outputting an enhancement layer stream; And modulating the enhancement layer stream based on one of the first and second layer modulation modes using different modulation schemes, and converting the symbols of the modulated enhancement layer stream based on the symbol positions of the base layer stream. Mapping to generate a transmission frame.

An apparatus for receiving digital multimedia broadcasting according to another embodiment of the present invention is a layer used for the transmission frame among the first and second layer modulation modes using different modulation schemes based on the layer modulation mode identifier included in the transmission frame. A receiver which identifies a modulation mode and separates a base layer transport stream and an enhancement layer transport stream from the transport frame based on the identified layer modulation mode; A base layer processor for demultiplexing the base layer transport stream; And an enhancement layer processor for demultiplexing the enhancement layer transport stream.

In a method for receiving a digital multimedia broadcasting by a digital multimedia broadcasting receiving apparatus according to another embodiment of the present invention, a first and second hierarchical modulation modes using different modulation schemes based on a hierarchical modulation mode identifier included in a transmission frame are provided. Determining a hierarchical modulation mode used for the transmission frame among the steps; Separating a base layer transport stream and an enhancement layer transport stream in the transport frame based on the identified layer modulation mode; Demultiplexing the base layer transport stream; And demultiplexing the enhancement layer transport stream.

According to the present invention, it is possible to provide a digital multimedia broadcasting transmitting and receiving apparatus and method capable of changing a modulation scheme of an enhancement layer stream according to a broadcasting environment.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

Now, a digital multimedia broadcasting transmitting and receiving apparatus and method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram conceptually illustrating an apparatus for transmitting digital multimedia broadcasting according to an embodiment of the present invention.

Referring to FIG. 1, the apparatus 100 for transmitting digital multimedia broadcasting according to an embodiment of the present invention includes a video encoder 101, an audio encoder 102, a base layer processor 103, an enhancement layer processor 104, and a transmitter. 105.

The video encoder 101 converts the video source into a base layer video stream and an enhancement layer video stream of improved quality, so that the base layer processor 103 and the enhancement layer processor 104 respectively. )

The audio encoder 102 converts an audio source into a base layer audio stream and an enhancement layer audio stream of improved quality, so that the base layer processor 103 and the enhancement layer processor 104 are respectively. )

The base layer processor 103 multiplexes the base layer video stream output from the video encoder 101 and the base layer audio stream output from the audio encoder 102 to output a base layer transport stream.

The enhancement layer processor 104 multiplexes the enhancement layer video stream output from the video encoder 101 and the enhancement layer audio stream output from the audio encoder 102 to output the enhancement layer transport stream.

The transmitter 105 selects a hierarchical modulation mode that determines a modulation scheme of the enhancement layer transport stream, modulates the enhancement layer transport stream in the selected hierarchical modulation mode, and then layeres the enhancement layer symbols on the base layer symbols. Mapping

In this case, the hierarchical modulation mode may be selected according to a digital multimedia broadcasting environment, for example, a channel, a broadcasting area, a network construction environment, a service requirement, a reception performance according to a moving speed, and the like. no.

For example, a digital multimedia broadcasting transmission apparatus capable of modulating an enhancement layer transport stream by binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) may be improved using a QPSK scheme when the network construction environment is good. When the layer transport stream is modulated and the network construction environment is relatively poor, the enhancement layer transport stream may be modulated using the BPSK scheme.

The hierarchical modulation mode may be variously selected according to the digital multimedia broadcasting environment. Hereinafter, the digital multimedia broadcasting transmitting apparatus 100 may select two modes shown in Table 1 as an example.

Hierarchical modulation mode Base layer Enhancement layer Modulation method Bits per symbol Modulation method Bits per symbol One π / 4-DQPSK 2 QPSK 2 2 π / 4-DQPSK 2 BPSK One

Referring to Table 1, regardless of the hierarchical modulation mode, the base layer is modulated in the same manner, and only the modulation method of the enhancement layer depends on the hierarchical modulation mode.

In the hierarchical modulation mode 1 (mode using QPSK as a modulation method), the base layer transport stream is modulated in the π / 4-DQPSK scheme, and the enhancement layer transport stream is modulated in the QPSK scheme, so that the base layer symbols and the enhancement layer symbols are modulated. Each represents two bits of data.

In addition, in the case of hierarchical modulation mode 2 (mode using BPSK as the modulation method), the base layer transport stream is modulated in the same manner as the hierarchical modulation mode 1 in the π / 4-DQPSK method, and the enhancement layer transport stream is used in the BPSK method. The base layer symbol represents two bits of data, and the enhancement layer symbol represents one bit of data.

2 is a diagram conceptually showing a transmitter 105 according to an embodiment of the present invention.

Referring to FIG. 2, the transmitter 105 according to an embodiment of the present invention includes an energy spreading scrambler 201, a convolutional encoder 202, a temporal interleaver 203, and a base layer frame generator for a base layer transport stream. 204, a base layer symbol mapper 205, a frequency interleaver 206, and a differential modulator 207,

A hierarchical modulation mode selector 208, an energy spreading scrambler 209, an internal encoder 210, a time interleaver 211, an enhancement layer frame generator 212, and an enhancement layer symbol mapper 213 for an enhancement layer transport stream. And frequency interleaver 214,

A hierarchical symbol mapper 215, an inverse fast Fourier transform unit 216, and a guard interval insertion unit 217 for the base layer and enhancement layer transport streams are included.

First, referring to the configuration of the base layer transport stream, the base layer transport stream output from the base layer processor 103 is energy dispersed in the energy spreading scrambler 201 and convolutionally encoded by the convolutional encoder 202.

The stream output from the convolutional encoder 202 is time interleaved by the time interleaver 203 in units of 16 logical frames, and the base layer frame generation unit 204 multiplexes time interleaved data to base layer frames. Create

Thereafter, the output of the time interleaver 203 is modulated in the QPSK scheme in the base layer symbol mapper 205, and frequency interleaved in the frequency interleaver 206, and then π / 4 DQPSK (Differential QPSK) in the differential modulator 207. Modulated in such a way.

Referring to the configuration of the enhancement layer transport stream, the hierarchical modulation mode selector 208 selects the hierarchical modulation mode according to the digital multimedia broadcasting environment. In this case, the selected hierarchical modulation mode is hierarchical modulation mode 1 or hierarchical modulation mode 2 described in Table 1.

The enhancement layer transport stream is energy dissipated in the energy spreading scrambler 209, and is error corrected encoded in a method such as a turbo code, a low density parity check (LDPC) code, or a convolutional code in the internal encoder 210 and output in units of logical frames. .

In hierarchical modulation mode 1, 2 bits of data are transmitted per symbol of the enhancement layer, whereas in hierarchical modulation mode 2, 1 bit of data is transmitted per symbol of the enhancement layer. In hierarchical modulation mode 1, it is half of the data transmitted by one symbol.

Therefore, even in the logical frame defined by the amount of data transmitted for 24 ms, the size of the logical frame is reduced by half compared to the hierarchical modulation mode 1 in the hierarchical modulation mode 2. That is, the size of the logical frame output in the hierarchical modulation mode 2 in the internal encoder 210 is half the size of the logical frame output in the hierarchical modulation mode 1.

Then, the time interleaver 211 performs time interleaving by adjusting the interleaving depth of the logical frame output from the internal encoder 210 according to the hierarchical modulation mode. 3 is a diagram for conceptually describing an operation of a time interleaver 211 according to a hierarchical modulation mode according to an embodiment of the present invention.

Referring to FIG. 3, in the hierarchical modulation mode 1, the time interleaver 211 performs time interleaving in units of 16 logical frames. That is, in the hierarchical modulation mode 1, the time interleaver 211 performs interleaving with a depth of 24 ms * 16 = 384 ms.

On the other hand, in the case of hierarchical modulation mode 2, the size of the logical frame output from the internal encoder 210 is half the size of hierarchical modulation mode 1, and the size of the memory required for interleaving is also reduced in half compared to hierarchical modulation mode 1. .

Therefore, in the hierarchical modulation mode 2, the time interleaver 211 inserts data corresponding to the next logical frame into the remaining half of memory, so that two logical frames constitute one unit for a total of 32 logical frames. Perform interleaving. That is, in the hierarchical modulation mode 2, the time interleaver 211 performs interleaving with a depth of 24 ms * 32 = 768 ms. As such, the deep interleaving depth ensures more robust reception performance in the communication environment.

Table 2 shows the index relationship between logical frames in the time interleaver 211 of hierarchical modulation mode 2 (mode using BPSK as a modulation method).

In Table 2, i _r denotes a bit index within one logical frame, r denotes a logical frame count input to a time interleaver, r 'denotes a logical frame count that is time interleaved and output, and R denotes i Shows the result of performing modulo 16 on _r .

Thereafter, the enhancement layer frame generator 212 generates an enhancement layer frame according to the hierarchical modulation mode based on the signal output from the time interleaver 211. The enhancement layer frame generated according to the hierarchical modulation mode will be described in detail below.

The enhancement layer symbol mapper 213 modulates the signal output from the time interleaver 211 by the QPSK method or modulates the BPSK method according to the hierarchical modulation mode.

In the hierarchical modulation mode 1, the enhancement layer symbol mapper 213 may map the output of the time interleaver 211 to the QPSK scheme, and the symbol mapping of the time interleaver 211 may be performed in the same manner as in Equation 1.

Here, p ^LP is an input bit of the enhancement layer symbol mapper 213, and q ^LP represents a position of a symbol output from the enhancement layer symbol mapper 213.

Table 3 shows constellation points of QPSK mapped enhancement layer symbols according to Equation 1 when hierarchical modulation mode 1, and FIG. 4 shows QPSK mapped enhancement layer symbols according to hierarchical modulation mode 1 according to an embodiment of the present invention. It shows the constellation of.

p ^LP q ^LP 1,1

0,1

0,0

1,0

In the hierarchical modulation mode 2, the enhancement layer symbol mapper 213 maps the output of the time interleaver 211 to the BPSK scheme, and the symbol mapping of the time interleaver 211 is performed in the same manner as in Equation 2 below.

Here, p ^LP is an input bit of the enhancement layer symbol mapper 213, and q ^LP represents a position of a symbol output from the enhancement layer symbol mapper 213.

Table 4 shows constellation points of BPSK mapped enhancement layer symbols according to Equation 2 in case of hierarchical modulation mode 2, and FIG. 5 illustrates BPSK mapped enhancement layer symbols according to hierarchical modulation mode 2 according to an embodiment of the present invention. It shows the constellation of.

p ^LP q ^LP 0 -One One One

Thereafter, the frequency interleaver 214 performs frequency interleaving on the signal output from the enhancement layer symbol mapper 213, and the hierarchical symbol mapper 215 performs enhancement layer on the base layer symbols modulated by the differential modulator 207. Map symbols hierarchically.

In the hierarchical modulation mode 1, the hierarchical symbol mapper 215 maps a QPSK modulated enhancement layer symbol to a differentially modulated base layer symbol using Equation (3).

Where q ^{HP - diff} represents a base layer symbol and q ^Hier represents a hierarchically modulated enhancement layer symbol. Table 5 shows constellation points of enhancement layer symbols hierarchically modulated by Equation 3, FIG. 6A shows hierarchical modulated constellations of odd-numbered symbols among OFDM symbols according to an embodiment of the present invention, and FIG. Represents a hierarchical modulated constellation of a symbol. 6A and 6B, white constellations represent base layer symbols, and black constellations represent enhancement layer symbols.

6A and 6B, α denotes a hierarchical modulation index. Referring to FIGS. 6A and 6B, the ratio of the distance a between enhancement layer symbols a between horizontally or vertically facing quadrants and the distance b between enhancement layer symbols in the same quadrant ( a / b). Further, the hierarchical modulation index α may vary depending on the reception condition, for example, the strength of the received signal, the performance quality of data included in the enhancement layer stream, that is, the required bit error rate (BER), the required packet error rate (PER), and the like. Can be.

In the hierarchical modulation mode 2, the hierarchical symbol mapper 215 maps the BPSK modulated enhancement layer symbols to the differentially modulated base layer symbols using Equation (4).

Where q ^{HP - diff} represents a base layer symbol and q ^Hier represents a hierarchically modulated enhancement layer symbol. Table 6 shows constellation points of enhancement layer symbols hierarchically modulated by Equation 4, FIG. 7A illustrates hierarchical modulated constellations of odd-numbered symbols among OFDM symbols according to an embodiment of the present invention, and FIG. Represents a hierarchical modulated constellation of a symbol. 7A and 7B, white constellations represent base layer symbols, and black constellations represent enhancement layer symbols.

Subsequently, the inverse fast Fourier transform unit 216 performs an inverse fast Fourier transform (IFFT) on the output signal of the hierarchical symbol mapper 215 to convert the signal into a time domain signal, and inserts a guard interval. In operation 217, data (protection interval) corresponding to about one quarter of the effective symbol period after the output signal of the inverse fast Fourier transform unit 216 is inserted before the valid symbol to remove the inter-symbol interference (ISI).

Now, a transmission frame according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 8 is a diagram illustrating a transmission frame generated by hierarchical modulation mode 1 according to an embodiment of the present invention, and FIG. 9 is a diagram illustrating a frame generated by hierarchical modulation mode 2 according to an embodiment of the present invention. It is a figure for following.

Referring to FIG. 8, the base layer frame 810 generated by the base layer frame generator 204 and the enhancement layer frame 820 generated by the layer modulation mode 1 in the enhancement layer frame generator 212 are respectively fast. Fast information channel (FIC) 811, 821 and main service channel (MSC) 812, 822.

Here, the FICs 811 and 821 are channels for transmitting data on the MSCs 812 and 822 and channels for transmitting information necessary for receiving a digital multimedia broadcasting signal, and include 12 fast information blocks (FIBs). do.

In addition, the MSCs 812 and 822 are channels for transmitting actual data, and include four common interleaved frames (CIFs), and the CIFs include 864 capacity units (CUs). Here, CU is the smallest unit that can be distinguished on the MSC, and its size is 64 bits.

In the hierarchical modulation mode 1, the hierarchically modulated transmission frame 830 in the hierarchical symbol mapper 215 includes a synchronization channel (Synchronization Channel, Sync.) 831, an FIC 832, and an MSC 833. , Sync. 831, FIC 832, and MSC 833 consist of 1, 3, 72 OFDM symbols, respectively, and a subcarrier of OFDM symbols for FIC 832, and MSC 833. Will transmit 4 bits of data (base layer 2 bits + enhancement layer 2 bits), respectively.

On the other hand, in the hierarchical modulation mode 2, the maximum transmittable rate is reduced to 1/2 compared to the hierarchical modulation mode 1, so that the enhancement layer frame generator 212 hierarchies the entire size of the enhancement layer frame 910. Reduce to 1/2 compared to modulation mode 1.

Referring to FIG. 9, the FIC 911 of the enhancement layer frame 910 generated by the layer modulation mode 2 in the enhancement layer frame generator 212 includes six FIBs and four CIFs in the MSC 912. The maximum number of CUs constituting one CIF is defined as 432 which is 1/2 of 864. That is, while the number of FIBs and the length of the CIF of the enhancement layer frame 910 generated by the layer modulation mode 2 are reduced by half, the number of CIFs is kept the same as the base layer frame 810.

Then, the hierarchically modulated transmission frame 920 in the hierarchical symbol mapper 215 includes a Sync 921, an FIC 922, and an MSC 923, for the FIC 922, and the MSC 923. Each subcarrier of an OFDM symbol transmits 3 bits of data (base layer 2 bits + enhancement layer 1 bit).

In the present invention, the digital multimedia broadcasting reception apparatus receives the hierarchical modulation information, thereby transmitting the hierarchical modulation information through the FIC for the base layer so that the enhancement layer frame can be received.

The FIC for the base layer has a plurality of fast information groups (FIG), and in the present invention, a case in which FIG transmits the hierarchical modulation mode will be described as an example.

FIG. 10 is a diagram illustrating a type 0 FIG (FIG 0/15) having an extended field of 15 according to an embodiment of the present invention.

FIG 0/15 (1000) includes a 3-bit FIG type 1001, a 5-bit Length 1002, and a 16-bit FIG data field 1003, and the 16-bit FIG data field 1003 is 1 bit. C / N (Current / Next, 1004), 1-bit OE (Other Ensemble, 1005), 1-bit P / D (1006), 5-bit Extension (1007), and 8-bit Type 0 field (1008) It includes.

The 8-bit Type 0 field 1008 includes a 2-bit hierarchical modulation field 1009, a 2-bit hierarchical modulation mode identifier 1010, and a 4-bit Rfu 1011.

The hierarchical modulation field 1009 stores information on a hierarchical modulation index α required for receiving an enhancement layer frame, and the hierarchical modulation mode identifier 1010 stores information on a modulation mode applied to the enhancement layer frame. The hierarchical modulation mode identifier 1010 may be defined as shown in Table 7.

Hierarchy Modulation Mode Identifier Hierarchical modulation mode 0 0 Hierarchical Modulation Mode 2 (BPSK Method) 0 1 Hierarchical Modulation Mode 1 (QPSK Method) 1 0 reserved 1 1 reserved

Referring to Table 6, when the value of 2 bits corresponding to the hierarchical modulation mode identifier is '00', it means that the enhancement layer transport stream is modulated by hierarchical modulation mode 2, that is, BPSK. In addition, when the value of 2 bits is '01', it means that the enhancement layer transport stream has been modulated by the hierarchical modulation mode 1, that is, the QPSK scheme.

Rfu 1011 is also a field reserved for future needs.

Now, a digital multimedia broadcasting receiver according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

11 is a diagram conceptually illustrating a digital multimedia broadcasting reception device 1101 according to an embodiment of the present invention.

Referring to FIG. 11, the digital multimedia broadcasting reception device 1101 according to an embodiment of the present invention includes a receiver 1102, a base layer processor 1103, an enhancement layer processor 1104, a video decoder 1105, and an audio decoder. 1106.

The receiver 1102 receives a transport frame from the digital multimedia broadcasting transmission device 100, and separates the base layer transport stream and the enhancement layer transport stream based on the hierarchical modulation mode included in the transport frame.

The base layer processor 1103 demultiplexes the base layer transport stream output from the receiver 1102 and outputs the base layer video stream and the base layer audio stream.

The enhancement layer processor 1104 demultiplexes the enhancement layer transport stream output from the receiver 1102 and outputs the enhancement layer video stream and the enhancement layer audio stream.

The video decoder 1105 may receive a base layer video stream processed by the base layer processor 1103 and an enhancement layer video stream processed by the enhancement layer processor 1104, and decode using only the base layer video stream. Both layer video streams and enhancement layer video streams may be used to decode high quality video services.

The audio decoder 1106 may receive the base layer audio stream processed by the base layer processor 1103 and the enhancement layer audio stream processed by the enhancement layer processor 1104, and decode them using only the base layer audio stream. Both layer audio streams and enhancement layer audio streams may be used to decode high quality audio services.

12 is a diagram conceptually illustrating a receiver 1102 according to an embodiment of the present invention.

Referring to FIG. 12, the receiver 1102 according to an embodiment of the present invention includes a guard interval removing unit 1201, a fast Fourier transform unit 1202, and a hierarchical symbol demapper 1203.

A differential demodulator 1204, a frequency deinterleaver 1205, a base layer symbol demapper 1206, a time deinterleaver 1207, a convolutional decoder 1208 and an energy spreading descrambler 1209 for the base layer transport stream Including,

A frequency deinterleaver 1210, an enhancement layer symbol demapper 1211, a time deinterleaver 1212, an internal decoder 1213, and an energy spreading descrambler 1214 for the enhancement layer transport stream.

The transmission frame received from the digital multimedia broadcasting transmitting apparatus 100 is removed from the guard interval removing section 1201, the fast Fourier transform section 1202 is converted to a signal in the frequency domain by the fast Fourier transform.

The hierarchical symbol demapper 1203 then selects the base layer transport stream and the enhancement layer transport stream based on the information on the hierarchical modulation index α and the hierarchical modulation mode included in FIG 0/15 1000 in the transport frame. Separate.

Specifically, the hierarchical symbol demapper 1203 first grasps the base layer signal, calculates a difference between the detected signal and the received signal, and de-maps the enhancement layer signal.

13 is a diagram conceptually illustrating a hierarchical symbol demapper 1203 according to an embodiment of the present invention. Referring to FIG. 13, the hierarchical symbol demapper 1203 according to an embodiment of the present invention includes a layer demodulator 1301, a base layer baseband processor 1302, a base layer FIC analyzer 1303, and an enhancement layer baseband. A processing unit 1304 and an enhancement layer FIC analysis unit 1305.

The layer demodulator 1301 separates the base layer frame and the enhancement layer frame based on the hierarchical modulation index α and the hierarchical modulation mode included in the transmission frame, and outputs the base layer frame to the base layer baseband processor 1302. The enhancement layer frame is output to the enhancement layer baseband processor 1304.

The base layer baseband processor 1302 outputs the FIC for the base layer output from the layer demodulator 1301 to the base layer FIC analyzer 1303, and the MSC for the base layer is differential demodulator 1204. )

The base layer FIC analyzer 1303 determines whether the broadcast signal is hierarchical modulation based on whether FIG 0/15 is included in the FIC received from the base layer baseband processor 1302. If it is determined that FIG 0/15 is included in the FIC, the hierarchical modulation index α and the hierarchical modulation mode included in FIG 0/15 are identified, and the hierarchical modulation index α and the hierarchical modulation mode are determined. )

Also, the base layer FIC analyzer 1303 analyzes information such as a transmission channel of data included in the MSC for the base layer.

The enhancement layer baseband processor 1304 outputs the FIC for the enhancement layer output from the layer demodulator 1301 to the enhancement layer FIC analyzer 1305, and outputs the MSC for the enhancement layer to the frequency deinterleaver 1210. do.

The enhancement layer FIC analyzer 1305 analyzes information such as a transmission channel of data included in the MSC for the enhancement layer.

Subsequently, the MSC signal for the base layer output from the hierarchical symbol demapper 1203 is demodulated in a differential QPSK (π / 4 DQPSK) scheme in the differential demodulator 1204, and frequency deinterleaving in the frequency deinterleaver 1205. And then demodulated in a QPSK scheme at base layer symbol demapper 1206.

The demodulated signal is then time deinterleaved at time deinterleaver 1207, decoded at convolutional decoder 1208, and then descrambled at energy spreading descrambler 1209.

In addition, the MSC signal for the enhancement layer output from the hierarchical symbol demapper 1203 is frequency deinterleaved in the frequency deinterleaver 1210, and the QPSK or BPSK scheme in the enhancement layer symbol demapper 1211 according to the hierarchical modulation mode. Demapping to

The demapped signal is then time interleaved by determining the interleaving depth according to the hierarchical modulation mode in the time deinterleaver 1212. Specifically, the interleaving depth is doubled in the hierarchical modulation mode 2 compared to the hierarchical modulation mode 1.

The time interleaved signal is then decoded in internal decoder 1213 and then descrambled in energy spreading descrambler 1214.

According to an embodiment of the present invention, the digital multimedia broadcasting transmission device 100 may transmit the enhancement layer signal to the digital multimedia broadcasting reception device 1101 by selecting a hierarchical modulation mode according to the digital multimedia broadcasting environment.

In addition, the transmission frame transmitted from the digital multimedia broadcasting transmission apparatus 100 includes information on the hierarchical modulation mode, so that the digital multimedia broadcasting reception apparatus 1101 identifies the hierarchical modulation mode for the enhancement layer in the transmission frame, and then grasps it. The enhancement layer signal can be demodulated according to the modulated modulation scheme.

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram conceptually illustrating an apparatus for transmitting digital multimedia broadcasting according to an embodiment of the present invention.

2 is a diagram conceptually showing a transmitter 105 according to an embodiment of the present invention.

3 is a diagram for conceptually describing an operation of a time interleaver 211 according to a hierarchical modulation mode according to an embodiment of the present invention.

4 illustrates a constellation diagram of QPSK mapped enhancement layer symbols by hierarchical modulation mode 1 according to an embodiment of the present invention.

5 illustrates a constellation diagram of BPSK mapped enhancement layer symbols in hierarchical modulation mode 2 according to an embodiment of the present invention.

FIG. 6A illustrates hierarchically modulated constellations of odd-numbered symbols among OFDM symbols according to an embodiment of the present invention, and FIG. 6B illustrates hierarchically modulated constellations of even-numbered symbols.

FIG. 7A illustrates hierarchically modulated constellations of odd-numbered symbols among OFDM symbols according to an embodiment of the present invention, and FIG. 7B illustrates hierarchically modulated constellations of even-numbered symbols.

8 is a diagram for describing a transmission frame generated by hierarchical modulation mode 1 according to an embodiment of the present invention.

9 is a view for explaining a frame generated by the hierarchical modulation mode 2 according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating a type 0 FIG (FIG 0/15) having an extended field of 15 according to an embodiment of the present invention.

11 is a diagram conceptually illustrating a digital multimedia broadcasting reception device 1101 according to an embodiment of the present invention.

12 is a diagram conceptually illustrating a receiver 1102 according to an embodiment of the present invention.

13 is a diagram conceptually illustrating a hierarchical symbol demapper 1203 according to an embodiment of the present invention.

Claims (19)

A base layer processor for outputting a base layer stream; An enhancement layer processor for outputting an enhancement layer stream; Modulating the enhancement layer stream based on one of the first and second layer modulation modes using different modulation schemes, and mapping symbols of the modulated enhancement layer stream based on symbol positions of the base layer stream A transmission unit for generating a transmission frame Digital multimedia broadcasting transmission device. The method of claim 1, The first layer modulation mode is a mode for modulating the enhancement layer stream in a QPSK scheme, The second hierarchical modulation mode is a mode for modulating the enhancement layer stream in a BPSK scheme. Digital multimedia broadcasting transmission device. The method of claim 1, The transmitting unit, An enhancement layer symbol mapper for modulating the enhancement layer stream based on the one layer modulation mode; And A time interleaver for performing time interleaving on the enhancement layer stream before modulating the enhancement layer stream, The time interleave depth in the first hierarchical modulation mode is different from the time interleave depth in the second hierarchical modulation mode Digital multimedia broadcasting transmission device. The method of claim 3, The first layer modulation mode is a mode for modulating the enhancement layer stream in a QPSK scheme, the second layer modulation mode is a mode for modulating the enhancement layer stream in a BPSK scheme, The time interleave depth in the second hierarchical modulation mode is twice the time interleave depth in the first hierarchical modulation mode. Digital multimedia broadcasting transmission device. The method of claim 3, The transmitting unit, An enhancement layer frame generation unit for generating a main service channel based on a common interleaved frame for the enhancement layer stream output from the time interleaver before modulating the enhancement layer stream; A length of the common interleaved frame in the first hierarchical modulation mode is different from a length of the common interleaved frame in the second modulation mode. Digital multimedia broadcasting transmission device. The method of claim 5, The first layer modulation mode is a mode for modulating the enhancement layer stream in a QPSK scheme, the second layer modulation mode is a mode for modulating the enhancement layer stream in a BPSK scheme, The length of the common interleaved frame in the second hierarchical modulation mode is twice the length of the common interleaved frame in the first modulation mode. Digital multimedia broadcasting transmission device. The method of claim 1, The transmitting unit, A hierarchical symbol mapper for mapping the output of the enhancement layer symbol mapper based on the symbol position of the base layer stream, The size of data transmitted by one symbol in the first hierarchical modulation mode is different from the size of data transmitted by one symbol in the second hierarchical modulation mode. Digital multimedia broadcasting transmission device. The method of claim 1, The transport frame includes a base layer fast information channel including base layer information, a base layer main service channel including a symbol of the base layer stream, an enhancement layer fast information channel including enhancement layer information, and a symbol of the enhancement layer stream. Includes the enhancement layer main service channel, The base layer fast information channel includes an identifier of a hierarchical modulation mode used by the transmitter. Digital multimedia broadcasting transmission device. The method of claim 8, The base layer fast information channel further comprises a hierarchical modulation index that determines the symbol location of the enhancement layer stream. Digital multimedia broadcasting transmission device. In the digital multimedia broadcasting transmitting apparatus transmits a digital multimedia broadcasting, Outputting a base layer stream and outputting an enhancement layer stream; And Modulating the enhancement layer stream based on one of the first and second layer modulation modes using different modulation schemes, and mapping symbols of the modulated enhancement layer stream based on symbol positions of the base layer stream Generating a transmission frame by Digital multimedia broadcasting transmission method. The method of claim 10, The first layer modulation mode is a mode for modulating the enhancement layer stream in a QPSK scheme, The second hierarchical modulation mode is a mode for modulating the enhancement layer stream in a BPSK scheme. Digital multimedia broadcasting transmission method. The method of claim 11, The generating may include modulating the enhancement layer stream based on the one layer modulation mode; And Performing time interleaving on the enhancement layer stream before modulating the enhancement layer stream, The time interleave depth in the second hierarchical modulation mode is twice the time interleave depth in the first hierarchical modulation mode. Digital multimedia broadcasting transmission method. The hierarchical modulation mode used for the transmission frame is identified among the first and second hierarchical modulation modes using different modulation schemes based on the hierarchical modulation mode identifier included in the transmission frame, and based on the identified hierarchical modulation mode. A receiver which separates a base layer transport stream and an enhancement layer transport stream in a transport frame; A base layer processor for demultiplexing the base layer transport stream; And An enhancement layer processor to demultiplex the enhancement layer transport stream; Digital multimedia broadcasting receiver. The method of claim 13, The transport frame includes a base layer fast information channel including base layer information, a base layer main service channel including a symbol of the base layer stream, an enhancement layer fast information channel including enhancement layer information, and a symbol of the enhancement layer stream. Includes the enhancement layer main service channel, The base layer fast information channel includes an identifier of a hierarchical modulation mode used by the transmitter. Digital multimedia broadcasting receiver. The method of claim 14, The base layer fast information channel further comprises a hierarchical modulation index that determines a symbol location of the enhancement layer stream, The receiving unit detects the position of the enhancement layer symbol based on the hierarchical modulation index. Digital multimedia broadcasting receiver. The method of claim 15, The first layer modulation mode is a mode for modulating the enhancement layer stream in a QPSK scheme, The second layer modulation mode is a mode for modulating the enhancement layer transport stream in a BPSK scheme. Digital multimedia broadcasting receiver. In the method for receiving a digital multimedia broadcasting, the digital multimedia broadcasting receiving apparatus, Identifying a hierarchical modulation mode used for the transmission frame among first and second hierarchical modulation modes using different modulation schemes based on the hierarchical modulation mode identifier included in the transmission frame; Separating a base layer transport stream and an enhancement layer transport stream in the transport frame based on the identified layer modulation mode; Demultiplexing the base layer transport stream; And Demultiplexing the enhancement layer transport stream; How to receive digital multimedia broadcasting. The method of claim 17, The transport frame includes a base layer fast information channel including base layer information, a base layer main service channel including a symbol of the base layer stream, an enhancement layer fast information channel including enhancement layer information, and a symbol of the enhancement layer stream. Includes the enhancement layer main service channel, The base layer fast information channel includes an identifier of a hierarchical modulation mode used by the transmitter. How to receive digital multimedia broadcasting. The method of claim 18, The first layer modulation mode is a mode for modulating the enhancement layer stream in a QPSK scheme, The second layer modulation mode is a mode for modulating the enhancement layer transport stream in a BPSK scheme. How to receive digital multimedia broadcasting.

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