WO2013023594A1

WO2013023594A1 - Method and device for transmitting and receiving digital audio signal in digital audio broadcasting system

Info

Publication number: WO2013023594A1
Application number: PCT/CN2012/080168
Authority: WO
Inventors: 邹峰; 李锦文; 申红兵; 陶涛; 高鹏; 雷文; 邢观斌
Original assignee: 国家广播电影电视总局广播科学研究院; 北京泰美世纪科技有限公司
Priority date: 2011-08-17
Filing date: 2012-08-15
Publication date: 2013-02-21
Also published as: CN102694764B; CN102694764A

Abstract

Provided in the present invention are a method and device for transmitting and receiving a digital audio signal in a digital audio broadcasting system. At a transmitting end, a code scrambling, LDPC coding, constellation mapping, and subcarrier interleaving are performed on service data, a code scrambling, convolution coding, bit interleaving, and constellation mapping are performed on service description information, while a convolution coding, bit interleaving, and constellation mapping are performed on system information, the information is multiplexed with a discrete pilot frequency and mapped onto a corresponding spectral pattern, thus constituting an OFDM frequency-domain symbol. A conversion from frequency-domain to time-domain is performed, connected into a logic layer frame structure, then a mapping and framing from the logic layer frame structure to a physical layer frame structure are performed for emission. The present invention designs a flexible spectral pattern on the basis of spectral characteristics of existing FM frequency bands, does not affect existing analog frequency modulation broadcast signals, and at the same time provides spectral expandability. A flexible system transmission parameter configuration is also provided, applicable in modes of single-frequency network and multi-frequency network.

Description

Digital audio signal transmitting and receiving method and device in digital audio broadcasting system

The present invention relates to the field of digital information transmission technologies, and in particular, to a digital audio signal transmission and reception method and apparatus in a digital digital audio broadcasting system. Background technique

The traditional FM band (87Mhz-108Mhz) is an FM broadcast band, which occupies 100KH or 200KHz. It can only provide users with the most basic broadcast services. At present, China still uses traditional analog FM radio. The use of digital audio broadcasting to provide digital audio and data services, broadcast, point-to-multipoint, a little bit opposite, the cost of broadcast information is independent of the number of users and sound quality, high reception quality, strong anti-interference, low transmission power, coverage large area. Whether it's audio quality, spectrum efficiency or support for new services, it has unparalleled advantages over traditional analog broadcasts.

At present, the main digital audio broadcasting technologies in the world mainly include the following:

(1) European DAB standards

It adopts COFDM-based multi-carrier broadband transmission technology. Compared with the narrowband transmission method in which one carrier transmits a program in traditional analog broadcasting, DAB technology has greatly improved performance against frequency selective fading caused by multipath propagation of electric waves. However, the channel bandwidth of the 1.432MHz DAB standard is completely incompatible with analog FM/AM broadcasting. New working frequency bands and frequency planning are needed, which poses a great obstacle to the promotion of DAB. At the same time, due to the broadband characteristics of the DAB system, the terminal receiver It is difficult to control in terms of cost and power consumption.

( 2 ) National Digital Audio Broadcasting National Standard HD Radio

Approved by the US FCC in 2002, it is based on iBiquity's in band on channel (IBOC) in-band co-channel technology. Since the FCC requires loose spectral masks for analog AM and FM emissions, the carrier frequency side is allowed to have a certain amount of power radiation. Based on this, HD Radio uses the carrier sidebands currently assigned to AM/FM analog stations to transmit digital audio signals and gradually achieves a smooth transition from analog to digital. The same frequency compatibility with traditional analog broadcasting has enabled HD Radio technology to be rapidly promoted in the United States, but since the frequency planning of AM/FM in other countries including China is different from that in the United States, and the corresponding spectrum mask is also It is much stricter than the FCC regulations. In addition, HD Radio uses fixed sideband and fixed sideband transmit power technology, which makes it interfere with existing analog coverage in other countries. It is difficult to have a large area in the world. Promotion.

(3) DRM It is a medium-to-short-wave AM broadcast digitalization solution implemented by DRM organizations. It has become the ITU and ETSI standards. Currently, DRM has released its evolution version DRM+ for digital audio broadcasting in the FM band. Unlike HD Radio, DRM can broadcast on the uplink/downstream of analog broadcasts or occupy a single broadcast channel. This method is flexible, and the digital spectrum can be placed in the least interference mode according to the situation of neighboring stations. The transmission of the transmit power is adjusted to protect the existing analog broadcast from being affected. However, the DRM system is a narrowband system like the traditional analog audio broadcasting. For frequency selective fading caused by multipath propagation of radio waves, frequency diversity cannot be achieved, and system performance is not ideal. And the DRM system can only support one broadcast channel band of lOOkhz, and can't support higher service data volume.

Therefore, the biggest difficulty encountered in the promotion of digital audio broadcasting technology is how to fully utilize advanced digital communication technology to improve the transmission quality, while at the same time taking into account the compatibility with analog broadcasting and frequency planning to meet the business needs of different users. It provides a flexible spectrum combination mode, which not only supports single-bandwidth service transmission but also supports flexible combination of multiple bandwidths, and supports larger transmission rate requirements by supporting larger transmission bandwidth. Moreover, based on the existing FM/AM transmitting equipment, a small amount of equipment and a small amount of investment can be added, and the digital audio signal can be transmitted on the same channel as the original analog broadcast signal. In this way, the original analog system is retained. On the other hand, it is not necessary to prepare a new frequency plan to achieve the purpose of frequency reuse. Summary of the invention

According to an aspect of the present invention, a digital audio signal transmitting method in a digital audio broadcasting system is provided, which includes the following steps: Sl: a transmitting end converts service data from an upper layer into a bit stream, performs scrambling; and then performs interference The service data bit stream after the code is LDPC-encoded; the LDPC-encoded service data bit stream is constellated; the sub-carriers carrying the service data after the constellation mapping are subcarrier-interleaved to form the inter-carrier interleaving. The service data subcarrier; S2, the transmitting end converts the service description information from the upper layer into a bit stream, and performs scrambling; then performs convolutional coding on the scrambled service description information bit stream; The information bit stream is bit-interleaved; the bit-interleaved service description information bit stream is constellated to form a service description information sub-carrier; S3, the transmitting end forms the system information bit stream according to a specific format, and then performs volume Product coding; comparison of convolutionally encoded system information bitstream Special interleaving; performing constellation mapping on bit-interleaved system information bitstream to form system information subcarriers; S4, generating discrete pilots in the frequency domain, and then interleaving the service description information including the service data subcarriers and the constellation mapping The data subcarriers of the subcarriers and the contiguous pilot subcarriers including the system information subcarriers are multiplexed together and mapped to corresponding spectrum modes to form OFDM frequency domain symbols; S5, the frequency domain is adopted by the IFFT converter Transforming the OFDM symbol into the time domain, and multiplexing the cyclic prefix to generate an OFDM time domain symbol; S6, multiplexing the plurality of OFDM time domain symbols together, and inserting the beacon, and connecting into a logical layer frame structure; S7, The logical layer frame structure performs mapping and framing to form a physical layer frame structure; S8, transmitting the physical layer frame structure by baseband to radio frequency conversion.

According to another aspect of the present invention, a digital audio signal transmitting apparatus in a digital audio broadcasting system is provided, including: a scrambler for performing bit stream conversion and scrambling on upper layer service data and service description information; a constructor for composing physical layer system information into a system information bit stream according to a specific format; an encoder, an upper layer service data bit stream for the scrambler output, a service description information bit stream output by the scrambler, and system information a bit stream is encoded; a bit interleaver, configured to perform bit interleaving on the encoded service description information bit stream and the system information bit stream; a constellation mapper, configured to perform bit-interleaved service description information, system information, and after encoding The service data is constellation mapping; the subcarrier interleaver is configured to perform interleaving on the subcarriers of the constellation mapped service data; the frequency domain symbol generator is used to map the discrete pilot and the constellation after the service description information and system Information, and subcarrier interleaved service data are multiplexed together Mapping to a corresponding spectral pattern to form an OFDM frequency domain symbol; an OFDM modulator for performing an IFFT transform on the OFDM frequency domain symbol into a time domain; an OFDM time domain symbol generator for outputting an OFDM modulator with a cyclic prefix Multiplexed together to form an OFDM time domain symbol; a time domain logical subframe component for multiplexing OFDM time domain symbols with beacons to form a physical layer frame structure; mapping and framing module for using the logic The layer frame structure performs mapping and framing to form a physical layer frame structure; and a transmitter is configured to transmit the physical layer frame structure by baseband to radio frequency conversion.

According to still another aspect of the present invention, a digital audio signal receiving method in a digital audio broadcasting system is provided, comprising the steps of: Sl, transforming a signal from a radio frequency into a baseband, capturing a baseband signal, performing timing synchronization and Carrier synchronization; S2, performing physical layer frame structure frame to logical layer frame structure mapping on the synchronized signal; S3, performing frequency domain transformation, channel estimation and equalization on the logical layer frame structure; S4, mapping and decoding the bit by the constellation Interleaving and convolutional decoding, extracting system information; extracting service description information by de-constellation mapping, de-interleaving, convolutional decoding, and descrambling; solving sub-carrier interleaving, de-constellation mapping, and LDPC decoding After the descrambling, the upper layer service data is extracted; S5, the service description information and the service data are sent to the upper layer.

According to still another aspect of the present invention, a digital audio signal receiving apparatus in a digital audio broadcasting system is provided, comprising: a timing synchronizer for timing synchronization and acquisition of a received signal; a frequency offset estimator for Frequency offset estimation on the signal on the timing synchronization; frequency offset compensator for compensating the frequency offset obtained by the frequency offset estimator back to the received signal; physical layer frame structure to logical layer frame structure inverse mapper for using the physical layer The frame structure is transformed into a logical layer frame structure by mapping. An OFDM demodulator, configured to perform FFT transformation on the synchronized signal, and transform from the time domain to the frequency domain; a channel estimator for estimating a frequency domain channel by a discrete pilot; a channel equalizer for compensating for the received frequency domain signal according to a channel parameter obtained by the channel estimator; a pilot and a data extractor for The spectrum mode extracts the service description information, the system information, and the service data subcarriers in the frequency domain respectively; the demodulation subcarrier interleaver is used to deinterleave the service data subcarriers; the constellation mapping inverse transformer is used to convert the frequency domain The channel-equalized service description information, the system information, and the constellation mapping symbols carried on the service data sub-carriers are mapped to the bit stream; the de-interleaver is configured to solve the inverse-transformed service description information and the system information bit stream. An interleaving map, the decoder, the service data bit stream inversely transformed by the constellation mapping, the service description information after decoding the bit interleaving, and the system information are decoded; the system information parser is configured to parse the decoded system information. ; the descrambler, the decoded service data stream and the service description information are solved .

The digital audio signal transmitting/receiving method and apparatus thereof in the digital audio broadcasting system of the present invention have the following advantages: Advanced encoding and modulation methods are adopted in the FM frequency band to ensure efficient and reliable transmission of audio data; And modulation combination, highly flexible, adaptable (~kbps) to high speed (~Mbps) range and scalability; and based on the spectrum characteristics of the existing FM band, flexible spectrum mode is designed, which does not affect the existing Analog FM broadcast signals with spectral scalability. The invention has flexible system transmission parameter configuration and can be applied to single frequency network and multi frequency network mode. In addition, the present invention can support multi-frequency coordinated operation, can improve spectrum utilization efficiency, and improve transmission characteristics under fading channels. And a flexible frame structure for low-power reception for controllable terminal cost and power consumption. DRAWINGS

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from

1 is a flow chart of a digital audio signal transmitting end according to an embodiment of the present invention;

2 is a schematic diagram of a signal baseband spectrum according to an embodiment of the present invention;

3 is a spectrum mode and NI value indication map in accordance with an embodiment of the present invention;

4 is a structural diagram of a subframe according to an embodiment of the present invention;

5 is a logical frame and physical layer frame structure diagram according to an embodiment of the present invention; FIG. 7 is a schematic diagram of a convolutional encoder according to an embodiment of the present invention; '7' FIG. 8 is a QPSK constellation according to an embodiment of the present invention. Mapping diagram

FIG. 9 is a schematic diagram of 16QAM constellation mapping according to an embodiment of the present invention; FIG.

FIG. 10 is a schematic diagram of a 64QAM constellation mapping according to an embodiment of the present invention; FIG.

11 is a schematic diagram of a filling manner of a subcarrier sub-matrix according to an embodiment of the present invention; FIG. 12 is a schematic diagram of a beacon structure according to an embodiment of the present invention; FIG.

13 is a schematic diagram of a synchronization signal pseudo-random sequence generator according to an embodiment of the present invention; FIG. 14 is an OFDM symbol configuration according to an embodiment of the present invention;

Figure 15 is a schematic illustration of a guard interval overlap in accordance with an embodiment of the present invention;

16 is a schematic diagram of selection of guard interval signals in accordance with an embodiment of the present invention;

FIG. 17 is a schematic diagram of a subframe mapping manner 1 according to an embodiment of the present invention; FIG.

FIG. 18 is a schematic diagram of a subframe mapping manner 2 according to an embodiment of the present invention.

FIG. 19 is a schematic diagram of a subframe mapping manner 3 according to an embodiment of the present invention.

20 is a flow chart of a digital audio signal receiving end according to an embodiment of the present invention;

Figure 21 (a) is a schematic diagram of a subcarrier index of an OFDM symbol when transmission modes 1 and 3 are transmitted according to an embodiment of the present invention;

Figure 21 (b) is a diagram showing the subcarrier index of the OFDM symbol in the transmission mode 2 according to an embodiment of the present invention. detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative only and not to be construed as limiting.

Embodiments of the present invention are digital audio signal transmitting methods in a digital audio broadcasting system. Referring to FIG. 1, the method includes the following steps: Sl: a transmitting end converts service data from an upper layer into a bit stream, and performs scrambling; and then performs LDPC encoding on the scrambled service data bit stream; and encodes the LDPC The service data bit stream performs constellation mapping; the subcarriers carrying the service data after constellation mapping are subcarrier interleaved in subcarriers to form interleaved service data subcarriers.

52. The transmitting end converts the service description information from the upper layer into a bit stream, and performs scrambling; then performs convolutional coding on the scrambled service description information bit stream; and performs bit-biting on the convolution-coded service description information bit stream. Interleaving; performing constellation mapping on the bit-interleaved service description information bitstream to form a service description information subcarrier.

53. The transmitting end groups the physical layer system information into a system information bit stream according to a specific format, and then performs convolutional coding; performs bit interleaving on the convolutionally encoded system information bit stream; performs constellation on the bit interleaved system information bit stream The mapping forms the system information subcarrier.

54. Generate a discrete pilot in the frequency domain, and then multiplex the interleaved data subcarrier including the service data subcarrier, the constellation mapped service description information subcarrier, and the contiguous pilot subcarrier including the system information subcarrier. And mapping to the corresponding spectrum mode to form an OFDM frequency domain symbol. 55. The frequency domain OFDM symbol is transformed into a time domain by an IFFT converter, and the cyclic prefix is multiplexed to generate an OFDM time domain symbol.

56. The multiple OFDM time domain symbols are multiplexed together, and the beacon is inserted and connected into a logical layer frame structure.

57. Map and frame the logical layer frame structure to form a physical layer frame structure.

58. The physical layer frame structure is transmitted by baseband to radio frequency conversion.

The digital audio broadcasting system may be a multi-carrier system employing Fourier transform, Walsh transform, or wavelet transform. It includes three OFDM transmission modes. Table 1 shows the system parameters for each transmission mode. The length of the subframes is 160ms in all three transmission modes. Defining the unit time T = 1/816000 seconds, various time-dependent parameter values can be expressed in multiples of T or approximate milliseconds.

Table 1: Transfer Mode System Parameters

In the above table, when the subcarriers in the upper half subband and the subcarriers in the lower half subband are not all virtual subcarriers, the number of effective subcarriers in the subband is in a valid subband. Half subband

When the subcarriers in the (or lower subband) are all virtual subcarriers, the number of valid subcarriers in the subband is

N _v / 2.

In this embodiment, the frequency pattern is composed of up to 8 subbands having a nominal bandwidth of 100 kHz. The frequency pattern specifies the number of subbands in the signal, as well as the locations of the effective subbands and the virtual subbands. In the partial frequency mode, all subcarriers in the upper half subband or the lower half subband of some valid subbands are virtual subcarriers.

Figure 2 shows the baseband spectrum of the signal. The 0 frequency point corresponds to the signal center frequency, which is the position of the OFDM symbol subcarrier 0.

This embodiment defines two types of frequency patterns, namely, a class A frequency pattern and a class B frequency pattern. The Class A frequency pattern includes 8 sub-bands, and the sub-band nominal frequency is ± (100 + 50) W3⁄4J = 0, 1, 2, 3; The B-type frequency pattern contains 7 sub-bands, and the sub-band nominal frequency It is an integer multiple of 100 kHz, ie ± * 10 (M3⁄4J = 0, 1, 2, 3.

Figure 3 illustrates that the present invention allows for the use of 39 spectral patterns and corresponding frequency pattern index, where ^ represents the number of interleaved sub-blocks. The bandwidth of each spectrum in the frequency mode is 50 kHz. In the frequency mode, the white block represents the spectrum that is not occupied, the shaded block represents the lower half of the effective subband, and the darkest gray represents the frequency band occupied by the analog station. Specifically:

The correspondence between the frequency pattern index 1-39 and the subband occupied by the corresponding frequency pattern is as follows:

01 B4

02 A4A5

03 B3B4B5

04 A3A4A5A6

05 B2B3B4B5B6

06 A2A3A4A5A6A7

07 B1B2B3B4B5B6B7

08 A1A2A3A4A5A6A7A8

09 A3A4A5A6

10 B2B3B4B5B6

11 A3A4A5A6A7

12 A2A3A4A5A6

13 A2A3A4A5A6A7

14 B1B2B3B4B5B6

15 B2B3B4B5B6B7

16 A3A4A5A6A7A8

17 A1A2A3A4A5A6

18 B1B2B3B4B5B6B7 19 A2A3A4A5A6A7A8

20 A1A2A3A4A5A6A7

21 A1A2A3A4A5A6A7A8

22 B3B4B5

23 A3A4A5A6

24 B2B3B4B5

25 B3B4B5B6

26 B2B3B4B5B6

27 A2A3A4A5A6

28 A3A4A5A6A7

29 B1B2B3B4B5

30 B3B4B5B6B7

31 A2A3A4A5A6A7

32 B2B3B4B5B6B7

33 B1B2B3B4B5B6

34 A1A2A3A4A5A6

35 A3A4A5A6A7A8

36 A2A3A4A5A6A7A8

37 A1A2A3A4A5A6A7

38 B1B2B3B4B5B6B7

39 A1A2A3A4A5A6A7A8

The spectrum mode index can be represented by 6 bits, and the correspondence between the bit definition and the index is as shown in Table 2. Table 3 shows the correspondence between the subband nominal frequency point position and the description bit. Table 4 shows the frequency pattern index corresponding to the two types of frequency patterns. Figure 21 (a) and (b) show the subcarrier index of OFDM symbols in different transmission modes, respectively. These two types of frequency patterns correspond to two kinds of spectrum subcarrier mapping modes, as shown in Table 5-8.

Table 2: Correspondence between bit definition and spectral mode index

Bit definition frequency mode index

000000 reserved

000001 1

000010 2

000011 3

000100 4

000101 5

000110 6

000111 7

001000 8

001001 9 001010 10

001011 11

001100 12

001101 13

001110 14

001111 15

010000 16

010001 17

010010 18

010011 19

010100 20

o 010101 21

o

010110 22

010111 23

011000 24

011001 25

011010 26

011011 27

011100 28

011101 29

011110 30

011111 31

100000 32

100001 33

100010 34

100011 35

100100 36

100101 37

100110 38

100111 39

Reserved Table 3: Correspondence between subband nominal frequency position and description bits

Spectral pattern corresponding to two types of spectral modes

Table 5: Class B Frequency Patterns Subcarrier Indexes for OFDM Symbols

Table 6: Subcarrier Indexes for Class A Frequency Pattern OFDM Symbols

Transmission mode 1 and 3 transmission mode 2 sub-frequency transmission corresponding to each sub-band center sub-band center sub-corresponding sub-plant corresponding

Band range (kHz) subcarrier index carrier index and frequency index subcarrier index

Frequency value rate value

Table 7: Subcarrier Index of the Class B Frequency Pattern Synchronization Signal

0~-50 -1 ~ -60 0kHz -1 ~ -30 0kHz

-50 ~ -100 -65 ~ -124 -125 -33 ~ -62 -63

B3

-100- -150 -126- -185 -99.6094kHz -64 - -93 -100.4063kHz

-150 ~ -200 -191 ~ -250 -251 -95 ~ -124 -125

B2

-200 ~ -250 -252- -311 -200.0156kHz -126 ~ -155 -199.2188kHz o

-250 ~ -300 -376 -158 ~ -187 -188

Bl

-300 ~ -350 -377 ~ -436 -299.625kHz -189 ~ -218 -299.625kHz

-350 ~ -400 ί Table 8: Subcarrier Index of the Class A Frequency Pattern Synchronization Signal

Transmission mode 1 and 3 transmission mode 2 frequency corresponding to each sub-band center sub-corresponding sub-band center sub-sub-band corresponding sub-

Surrounding (kHz) carrier index and frequency carrier wave carrier index and frequency carrier index

Rate value

400 ~ 350 499 ~ 440 439 250 ~ 221 220

A8

350 ~ 300 438 ~ 379 349.8281kHz 219-190 350.6250kHz

300 ~ 250 374-315 314 187-158 157

A7

250 ~ 200 313-254 250.2188kHz 156-127 250.2188kHz

200 ~ 150 248 - 189 188 124 ~ 95 94

A6

150 ~ 100 187-128 149.8125kHz 93~64 149.8125kHz

100 ~ 50 123 ~ 64 63 61-32 31

A5

50~0 62~3 50.2031kHz 30~1 49.4063kHz

0~-50 -3 ~ -62 -63 -1 ~ -30 -31

A4

-50 ~ -100 -64~ -123 -50.2031kHz -32 ~ -61 -49.4063kHz

-128-

-100- -150 -64 ~ -93

-187 -188 -94

A3

-189- -149.8125kHz -149.8125kHz

-95 ~ -124

-248

-254 ~

-200 ~ -250 -314 -127- -156 -157

A2 -313

-250.2188kHz -250.2188kHz

-250 - -300 -315- -158- -187 -374

-379 ~

-300 ~ -350

-438 -439 -220

Al

-350 ~ -400 -440 ~ -349.8281kHz -350.6250kHz

- 499 In this embodiment, the superframe length is 2560 ms, and each superframe is composed of four physical layer signal frames of length 640 ms, and each physical layer signal frame includes four subframes having a length of 160 ms, and each subframe includes one subframe. The beacon and the OFDM symbols are shown in Figure 4. Each physical layer signal frame carries data for one logical frame. The logical frame structure and physical layer signal frame structure are shown in Figure 5. The physical layer signals are transmitted in order from left to right as shown in FIG.

The system information consists of 72 bits, including two parts of 36 bits, and the system information 1 includes 36 bits. The bits and corresponding information are shown in Table 9.

Table 9: Bit Descriptions for System Information 1

o o

Multi-frequency point cooperative working mode indication, 0 means multi-frequency point working together; 1 means non-multi-frequency point working together;

Bi ~ ^{b The} frequency of the multi-frequency point working together in the next sub-frame, the unsigned integer represented by ~ is /, and the multi-frequency point cooperative working frequency of the next sub-frame is ( + G^ ⁵ * )^^^ , in the non- When multi-frequency points work together, ^ ~ is the most significant bit among them;

. ~ current subband nominal frequency point;

^14 - ^: frequency pattern index;

H. Retain Rfa, reserved for future expansion;

27 ~ ^b 29 - CRC check digit;

. ~ ^ ³⁵ : Retain Rfu, reserved for future use;

System information 2 includes 36 bits, and its bits and corresponding information are described in Table 10. Table 10: Bit Descriptions for System Information 2

C° ~ ^Cl : the position of the current physical layer signal frame in a superframe, 00 represents the first frame; 01 represents the second frame; 10 represents the third frame; 11 represents the fourth frame;

^C2 ~ ^3: current subframe position in one physical layer signal frame, 00 denotes a first sub-frame; second sub-frame represents 01; 10 denotes a third sub-frame; 11 indicates a fourth sub-frame;

4 ~ ^C5 : subframe allocation mode, 00 reserved; 01 means subframe allocation mode 1; 10 means subframe allocation mode 2; 11 means subframe allocation mode 3;

C6 ~ ^c i . The modulation mode of the service description information, 00 means QPSK; 01 means 16QAM;

10 means 64QAM; 11 reserved;

c ₈ ~ ^c 9: modulation mode of service data, 00 means QPSK; 01 means 16QAM; 10 means 64QAM; 11 reserved;

^Cw - ^{l 1} : hierarchical modulation indication of service data, 00 means that layered modulation is not supported; 01 means support for layered modulation and α = 1; 10 means support for layered modulation and α = 2; 11 means support for layered modulation and α = 4;

The coding of service data adopts the indication of uniform protection, 0 means no uniform protection; 1 means uniform protection;

Ci 3 ~ ^c u: LDPC code rate of service data, 00 means 1/4 code rate; 01 means 1/3 code rate; 10 means 1/2 code rate; 11 means 3/4 code rate;

l ⁵ ~ ^Cl6 : LDPC code rate of service data, 00 means 1/4 code rate; 01 means 1/3 code rate; 10 means 1/2 code rate; 11 means 3/4 code rate; In the case of non-hierarchical modulation, the coding rate of the service data when the uniform protection is used is indicated by ^~; if the non-uniform protection is used, the coding rate of the service data is obtained from the service description information; The coded rate of the high-protected service data is indicated by ~, and the coded rate of the low-protected service data is from ^C 15 to ^C 16;

^Ci7 ~ ^C26 : Retain Rfa, reserved for future expansion;

^C 27 ~ ^C 29: CRC check digit;

Retain _Rfu and keep it for future use.

The scrambling code for the service data bit stream and the service description information bit stream in this embodiment is specifically a binary pseudo random sequence scrambling code processing, and the binary pseudo random sequence is generated by a linear feedback shift register, and the shift register is The initial value is 000000000001 and the generator polynomial is: x ⁿ + x ⁿ + x ^& + x ⁶ + l . Figure 6 shows the linear feedback shift register that generates the scrambling code, resetting the linearity at the beginning of each logical frame. Feedback shift register.

The scrambling code is implemented by modulo-adding the input bit information sequence and the binary pseudo-random sequence, see equation (1):

y(c ') ten _{( 1 )}

In the formula:

X^——pre-scrambling information bits

γ^-one scrambled bit

Forward error correction coding is performed on the scrambled bit stream. Different information in the logical frame adopts different forward error correction coding modes, wherein LDPC coding is used in the service data, and the service description information and system information are convolutional coding.

Convolutional coding of the scrambled service description information and system information is performed by using a 1/4 convolutional code with a constraint length of 7. The encoder of the convolutional code is as shown in FIG. 7, and the corresponding octal generator polynomial is: 133, 171, 145, 133. The initial value of the shift register is all "0". System information 1 and system information 2 are independently convolutionally encoded. The linear feedback shift register is reset at the beginning of each logical frame for the service description information, and the linear feedback shift register is reset at the beginning of each logical sub-frame for system information. The low bit of the system information bit stream is first, or ^c . in front.

The code rate for performing LDPC encoding on the scrambled service data bit stream may be 3/4, 1/2, 1/3, and 1/4, and the output codeword length is 9216 bits, and the code rate is 3/4. The corresponding input information bit length is 6912; when the code rate is 1/2, the corresponding input information bit length is 4608; when the code rate is 1/3, the corresponding input information bit length is 3072; when the code rate is 1/4, corresponding The input information bit length is 2304. The corresponding relationship is shown in Table 11. Table 11: LDPC Encoding Configuration

By inputting information bits ^{m =} { ^m . , "","i} and check bits Ρ = { », Α,···, /1⁄2 ₁₅

LDPC output code word ^^^, ,..., ^ ^,^! ,...^^,/^,/^,.../^ ― , where check bit P = { . , ..., P —κ I is obtained from the check matrix H by solving the following equation:

Hxc ^T =0 (2)

In the formula:

0—— ( 9216-K ) row 1 column full 0 column vector

H——LDPC parity check matrix

The convolutionally encoded service description information and system information are bit interleaved, and the interleaving is performed in units of interleaved blocks. The interleaving algorithm is as follows: For the input sequence before interleaving

_{_{Z = (Z 0, Z 1}} , Z 2, ..., Z NMUS _ 1)? W _Mra wherein the length of the interleaved block, the interleaved output sequence ζ, =

, where ₌ is obtained by:

For(i = 0,n = 0;i <s;i + +) if (p(i)<N _MUX )

R(n) = pii)

n + +;

}

Where p(0) = 0, p(i) = (5 p(il) + q) mod s, (i≠ 0) _{? s} = 2! , <

Set the value for the system.

In other words, it is obtained as follows:

Ρ(0)=0, ^ = 2' , q = sl^-l.

p(i) = (5x p(i-l) + q)mods,(i≠ 0) .

The initial value of n is 0. In the range of 0 ≤ < s, the P(i) value is calculated in turn. If the condition (Pi^Ww) is satisfied, then R(n)=P(i), and let n =n+l; Otherwise, the P(i) value obtained is discarded, and the value of n is unchanged. Continue to use the P(i) value obtained by subsequent calculation to judge the condition until all R(n) values are 0≤ n ≤ N _MUX _ ; N _MUX = v * N _{ , where V is the system setting value, which is the number of interleaved sub-blocks, that is, the number of occupied spectral sub-bands. When performing bit interleaving on the convolutionally encoded service description information bit stream, the V is based on the difference between the constellation mapping mode and the transmission mode, and the value is the reference table 12, and the logical frame includes the interleaving block, that is, the binding is performed. The number of sub-bands, the value of ^ is shown in Figure 3. Table 12: Value of V

The system information includes system information 1 and system information 2. The system information 1 and the system information 2 after convolutional coding are respectively bit interleaved by using the above method, and the lengths of the two interleaving blocks are all 144.

Performing constellation mapping on the LDPC-encoded service data bit stream and the bit-interleaved service description information bit stream includes performing a QPSK mapping manner, a 16QAM mapping manner, or a 64QAM mapping manner, and performing the bit-interleaved system information bit stream. Constellation mapping includes QPSK mapping.

The bit stream ^v after bit interleaving. , Ν ι, ^{^v} 2 ... mapped to QPSK, 16QAM or 64QAM symbol streams transmitted symbols mapped added power normalization factor so that the average power of the symbols mapped convergence. The modulation mode supports non-hierarchical modulation and layered modulation.

The QPSK mapping will have 2 input bits ( ^V ₂ ', ^V ₂ '", ^{= ( 2} , mapped to I value and Q value each time. The mapping method is shown in the figure below. The power normalization factor is already included in the constellation diagram. The value in is: when the system information QPSK is mapped = ^, when the service data and the service description information QPSK are mapped ^{= 1.} The constellation mapping mode of QPSK is shown in Fig. 8.

The 16QAM mapping maps 4 input bits (^, ^", ^, ^, ⁰ , ¹ , ² , ...) to I value and Q value each time. The mapping mode is shown in Figure 9. The power is normalized in the constellation diagram. Factor.

The 64QAM mapping maps 6 input bits ^, ^", ⁷ ^, ' , ⁷ ^, ' , ⁰ , ¹ , ² , ... ) to I value and Q value each time. The mapping method is shown in Figure 10. A power normalization factor is included.

Each of the active subbands and the contiguous pilots in the lower half of the subbands each hold 72 system information symbols, wherein when the subcarriers are not all virtual subcarriers, the lower subbands of the effective subbands The continuous pilot places system information 1 symbol; when its subcarriers are not all virtual subcarriers, the continuous pilot of each upper subband of each effective subband places system information 2.

Two scattered pilots by the pseudo-random sequence _{ΡΙ = ΡΙ "ΡΙ 2 '··} Ά ··' ΡΙ Ρ1, and Ρβ ^ / ^, / ^, ···, / ^ ·, ···, / ^} in The bit stream pair /^Ά/^,···, /^/^ is composed of symbols generated by QPSK mapping in turn, and the value of ^ is in transmission mode 1 and transmission mode 3 ^{bZ Ν} ' , when in transmission mode 2. A binary pseudo-random sequence Pi of length ^ is generated by the linear feedback shift register shown in FIG. 13, and the generator polynomial of the linear feedback shift register is: x ^u + x ⁹ + l , the initial value is 01010100101

The system information is transmitted in units of one logical subframe, and the service description information and service data are transmitted in units of one logical frame. The system information symbols are transmitted three times in a logical sub-frame.

For each spectrum mode, subcarriers other than the virtual subcarrier, the contiguous pilot subcarrier, and the scattered pilot subcarrier in the OFDM symbol are data subcarriers, and the data subcarriers are placed with service description information symbols and service data symbols. For the spectrum mode shown in Figure 3, (4*^)* (*N valid subcarriers) are included in one logical frame.

Specifically, performing subcarrier interleaving on the subcarriers carrying the service data after the constellation mapping in step S1, the subcarrier interleaving further includes:

Constructing a subcarrier matrix M with a row number of ⁴ * and a column number of *, the ^V is the number of OFDM symbols in each subframe, and the number of effective subcarriers included in one subband in one OFDM symbol, The number of subbands participating in the bundling is as shown in FIG. 3; the number of rows and the number of columns of the subcarrier matrix are counted from 1; the subcarrier matrix is pressed from top to bottom and from left to left. The right average is divided into sub-matrices ^, ', where the number of rows is ^ V and the number of columns is:

M 1,1

Μ ₂

M

M _{3 3} Μ ₃

Μ 4,Ν, where M _si = (m _a , _fc ) _x ,

m _fl ( = l, ² ,... , b = l, ² , '", W _v ) denotes the data elements in the submatrix.

In the subcarrier matrix M, discrete pilot data elements are placed in predetermined positions in each submatrix ^M ".

System information is transmitted in units of one logical sub-frame. In the subcarrier matrix M, starting from the submatrix ^ ^{1 of the} first column on the left, system information 1 and system information carried by a logical sub-frame in the order of sub-matrices from left to right and top to bottom The data elements of 2 are collectively placed 3 times in a predetermined area in one of the above.

Service description information and service data are transmitted in units of one logical frame. In the subcarrier matrix M, starting from the submatrix M _{u of the} first column on the left side, the data elements of the service description information symbol carried by one logical frame are placed in order from left to right and top to bottom. In the 1st to Nth rows of M _si and in the 1st to AU _Sv ^ columns in the Nth _SDiS „+l row, the logical frame bearer is placed in order from the top to the bottom and the left to the right submatrix. a data element describing a service description information symbol, N. and ^ _S » set values for the system ₍

In the subcarrier matrix M, starting from the submatrix M _{u of the} first column on the left side, the data elements of the service data symbols carried by one logical frame are placed in the order from left to right and top to bottom. The residual data of the _si , and the data elements of the service data symbol carried by the logical frame are sequentially placed in the order of the sub-matrix from top to bottom and left to right.

Wherein the position of the continuous pilot of the data element of the system information symbol placed in the sub-matrix is as shown in Table ₁₃ below, depending on the transmission mode. Within one logical sub-frame, 72 system information symbols of system information 1 and system information 2 are repeated three times. For example, in transmission mode 1, the position information specified in Table 8 of lines 1 to 18 of ^M " is placed with system information 1 and The 72 system information symbols of system information 2, the same system information symbols are placed in the designated positions of lines 19 to 36 and lines 37 to 54, respectively.

Table 13: Data Elements of System Information Symbols Placed in Submatrix "Continuous Pilot Locations Transfer Modes 1 and 3:

In transmission mode 1: the 11, 55, 75, 103, 144, 164, 192, 228 columns in the 55 ~ 56 rows of ^ " are filled with the system information symbols placed in 1 ~ 2 rows; in transmission mode 2 : In the "109 to 111 lines, 15, 43, 84, 104 columns are filled with system information symbols placed in 1 to 3 lines; in transmission mode 3: in "55 to 61 lines, 11, 55, 75, 103, 144, 164, 192,

The system information symbol placed on the 228 column is filled with 1 to 7 lines.

The discrete pilot data elements are placed in the sub-matrix according to the transmission mode Each row; the data element of the discrete pilot is placed in the submatrix ^" where the position b is:

Transmission mode 1 and transmission mode 3:

T _f mod(a - 1, 3) == 0

12/7 + 122 ρ = 0,1,···,10

b

12ρ + 121 ρ = -10, -9,···, -1,0

Mod(a-l,3) 1

Transmission mode 2:

? Mod(a-l,3) 0

Mod(a-l,3)

12/7 + 70 ρ = 0,1,2,3,4

b

12/7 + 53 ρ = -4,-3,-2,-1,0

l<a<S

among them

The subcarrier matrix M is equally divided into the number of rows from the top to the bottom, and the sub-moments of the number of columns is

Μ

M

Array M _u = (m _c ) _SNX{NvXNi) ( _W = 1, 2, 3, 4) , ie M

The length of the ^ symbol from left to right, top to bottom are sequentially filled in a manner subcarrier matrix ^Μ "on lines 1 to 3 of the discrete pilot elements, ^Μ" row 4 to row The discrete pilot elements are filled as follows, where ⁴ ≤ : if m. d( _c -l, ³ )==0 , then the value on the discrete pilot of the ith row is placed on the discrete pilot of the row;

If the scattered pilot _{^{mod (c -l, 3) ==}} l, the frequency of this line is placed on the _second row of discrete conductive elements on a frequency value;

If mod( _C -l, ³ )== ² , then the value on the third row of discrete pilot elements is placed on the discrete pilot of this row.

The service description information after scrambling, encoding, interleaving and constellation mapping is placed on the upper finger. Given data elements, data elements ^M "data element position placing table 14. A service description information ^M" in the first to N-th row are in the service description information, row N + ¹ in the first to ^M

The data element of ^« ^^ is the business description information. The service description information is filled in from the left to the right and from the top to the bottom, and the data elements specified in the sub-sub-matrix ^Mu in the table 14 are filled in, and then the corresponding data elements in each sub-carrier sub-matrix are sequentially filled according to the direction indicated by the arrow in FIG. 11 . .

Table 14: _{Values of} N _SD1Sn and N _saSvaM

The subcarrier matrix M removes the data elements outside the service description information and places the service data in one logical frame. The service data firstly follows the subcarrier submatrix from left to right and top to bottom.

^M "in the corresponding data element filled exhausted, and then the direction of arrow 11 indicated in FIG sequentially filling the respective sub-carriers corresponding data element in sub-matrix. Table 15 shows the transmission mode in each submatrix 4 subcarriers

The number of data elements in which the service description information is placed and the number of data elements in which the business data is placed.

Table ₁₅ , ₂ , 3, 4, 4, '=1, ² , ···, ) The number of data elements of the service description information placed and the number of data elements in which the business data is placed

Placing the data elements of the business data symbols are interleaved sub-matrix, the interleaving interleaved block as a unit, a transmission mode and a transmission mode of the interleaved block length ^N MUX 2 is 46080, the transmission mode of the interleaved block 3 The length is 50688;

The interleaved blocks are constructed as follows:

1) Record a row of the subcarrier matrix M as M _t = [Μ _;1 , Μ!·, ₂ , · · · , M _iNi ] = [m _Uil , m _2il , --- m _N , _;1 , m _{l i2} , m _{2; 2} , · · · m _N , !·, ₂ , · · · , m _liNi , m _2iN/ , --- m _N ,. _W J where

m

^M ", the component is constituted by a continuous ^{^{^{M, M" = [M "}}} , ', M is ^M" component, corresponding to the first order' element row;

2) Replace the data elements of the business data with ^ ¹ , ² ,...,^ ': " in ^, ^ W

among them,

^V consists of consecutive P components, ^VC "

, is the component of VC _j , the data element of the business data in ^VC '-(TM _OTS „,; 'place ^M ', ie ^ ₊ 1^ _∞ , _; ' the data element of the first business data in the placement, P The number of data subcarriers in which the service data is placed within a valid subcarrier;

Where the correspondence between z and is:

j = ((iN _{SDISn -lk} *N _SDISn )*(N _I -l) + (ll))modN _I +l.

k = 0,1,2,3

i = k*S _N +N _SDISn +l,k*S _N +N _SDISn +2,...,(k + l)*S _N

3) sequentially extract the first sub-vector according to the row number, and construct a one-dimensional vector ( ^VC 1 J '·" ), that is, the first interleaving block;

Interleaving the bit-interleaving algorithm yields ^=(V< ^,''' ^V G^-A „W) , where

^VC = 1 ^ ^·^<^ , put ^VC in the one-dimensional vector BA' j = 1, 2,...; _d into the matrix Μ _ι7 (/ = 1, 2, ···, ^), in VC The elements are placed one by one on the data element of the business data in ', ie, the data element of the first business data in 'place ^M W , ', / the corresponding relationship is:

y = (( -l)*(V _i -l) + (/-l))modN _i +1.

k = 0,1,2,3

i = k^S _N - N _SDI + *(S _N -N _SDISn ) + 2,...,(k + l)*(S _N -N _SDISn ) .

:0

The bit interleaving algorithm is:

For the input sequence before interleaving: ^) where is the length of the interleaved block, and the output sequence after interleaving is ² ' ^{= ( 2} 1' -1) , where = w, obtained by:

If (p(i)<N _MUX )

R(n) = pii)

n + +;

In other words, the WW is obtained as follows:

Log

P(0)=0, ^ = 2' -' , q = s/4-l.

p(i) = (5x p(i-l) + q) mod s, (i≠ 0) .

The initial value of n is 0. In the range of 0≤z'<s, the P(i) value is calculated in turn. If the condition (P(i)<^) is satisfied, then R(n)=P(i) ), and let n = n + l; otherwise the P (i) value is discarded, the n value is unchanged, continue to use the subsequent calculated P (i) value for conditional judgment, until all R ( n) value ( 0<n<N _MUX -1 )

Each row element in the subcarrier matrix is padded to the effective subcarrier of each OFDM symbol from left to right, wherein the first element of each row in the matrix is padded to the effective subcarrier with the smallest subcarrier index in the OFDM symbol. See Table 5-8

Each OFDM symbol contains ^ subcarriers, when transmitting mode 1 and transmission mode 3, ^ = ²⁰⁴⁸ ; when transmitting mode 2, = ^1Q24 . Corresponding to the various spectrum modes, the subcarriers in the corresponding effective subband are not all of the virtual subcarriers. The upper/lower subbands contain ( ⁴ *)*(Λ^Λ^ effective subcarriers. The remaining subcarriers are virtual subcarriers. , virtual subcarrier is 0

^ subcarriers are mapped to OFDM symbols by IFFT, and the mapping method is shown in equation (3):

In the formula:

^S - ^(t) - the "first OFDM symbol" in a subframe

The ''subcarriers of the first OFDM symbol

The structure of the beacon is as shown in FIG. 12, and includes a ⁷ ^ cyclic prefix and two identical synchronization signals W. For a band-limited pseudo-random signal, the length is ^T _b = ^T J ² .

n(n + l)/2

P _b (n) = exp -){-\) ⁿ 2nq- n = 0,l,---,L*N, -1

A random sequence of length L (see Table 16 for the value of L) is generated by the equation Nzc, where in the transmission mode 1 and the transmission mode 3 Λ3⁄4·

= 48, in transmission mode 2 ^3⁄4 = 487 , = 12

According to the spectrum mode, the elements in the random sequence P _b (n, n, are sequentially padded from left to right onto the effective subcarrier of the OFDM symbol of the synchronization signal, wherein the first element of the random sequence is filled into the OFDM symbol subcarrier of the synchronization signal On the valid subcarrier with the smallest index, see Table 5-8.

In the middle

Number of subcarriers of the synchronization signal

The first subcarrier of the OFDM symbol of the synchronization signal

Subcarrier spacing of the synchronization signal

Table 17: Parameters related to the synchronization signal

The structure of the OFDM symbol is shown in Figure 14. It consists of a cyclic prefix of length and an OFDM data body of length ".

Between adjacent OFDM symbols and the beacon by a guard interval (GI) overlap with each other, the length of the GI in Table 13 ^ ^7. ^W W adjacent symbols after weighting window function, the tail of the previous symbol and GI after a head GI symbols are superimposed, superimposed manner shown in Figure 15, while in FIG. ⁷ ^ OFDM symbol τ = τ, when the beacon ,

+ T _u + T _g

In the middle

The value of —— is shown in Table 18

τ

Table 18: Length of guard interval

The protection interval signal selection method is shown in Figure 16.

In this embodiment, each logical frame includes 4 logical subframes, and each logical subframe includes ^0 FDM symbols and 1 beacon symbol. The step of sub-frame allocation for logical sub-frames in four consecutive logical frames ( ^{ρ = 1} ' ² ' ³ ' ⁴ '^ ^{= 1} ' ² , ³ ' ⁴ ) indicates the third logical frame Logical subframes. Three different sub-frame allocation methods can be used, as shown in Figure 17, Figure 18 and Figure 19.

As shown in FIG. 17, the subframe allocation mode 1: The physical frame of the 4 logical subframes in one logical frame constitutes one physical superframe. That is, the subframe allocation mode 1 does not change the original order of the four logical subframes in each logical frame.

As shown in FIG. 18, subframe allocation mode 2: grouping 8 consecutive logical subframes in the two consecutive logical frames, interleaving the logical subframes in the group, and interlacing the groups The logical subframe is mapped to 2 consecutive physical frames, and the 4 physical frames constitute 1 physical superframe.

As shown in FIG. 19, the subframe allocation mode 3: groups the 16 consecutive logical subframes in the four consecutive logical frames, and sequentially sets the ith logical subframe in each logical frame of the group. Mapping to the i-th physical signal frame, where i is 1, 2, 3 or 4 to form 4 consecutive physical frames, and 4 of the physical frames constitute 1 physical superframe.

In addition, in other embodiments, the digital audio broadcasting system may also be assigned a specific multi-frequency coordinated working sequence, wherein the frequency of the first physical subframe of the first physical frame of each physical superframe The multi-frequency point cooperative work information of the next subframe is included in each physical sub-frame, and the multi-frequency point cooperative working information includes multi-frequency point cooperative working mode indication and multi-frequency point cooperation of the next sub-frame. The working frequency point, the multi-frequency point cooperative working information may be carried by the system information.

More specifically, in the S1, the service data from the upper layer may be layered according to different priorities, and the multi-layer service data is converted into a bit stream, and then separately scrambled and LDPC-encoded; The layer service data bit stream is respectively subjected to constellation mapping to obtain a plurality of modulation symbols; and the plurality of modulation symbols are multiplexed in the same constellation space according to a power loading manner to obtain a layered modulation symbol. In the service data bit stream, the first layer is a high priority data stream, and the other layer is a low priority data stream.

Corresponding to the transmitting method, the present invention also provides a digital audio signal transmitting apparatus in a digital audio broadcasting system, comprising: a scrambler for performing bit stream conversion and interference on upper layer service data and service description information. a system information constructor for composing physical layer system information into a system information bit stream according to a specific format; an encoder, an upper layer service data bit stream for the scrambler output, and a service description information bit output by the scrambler The stream and the system information bit stream are encoded; the bit interleaver is configured to perform bit interleaving on the encoded service description information bit stream and the system information bit stream; the constellation mapper is configured to perform bit interleaved service description information and system information. And the encoded service data is subjected to constellation mapping; the subcarrier interleaver is configured to perform interleaving on the subcarriers of the constellation mapped service data; and the frequency domain symbol generator is configured to map the discrete pilot and the constellation Descriptive information and system information, and subcarrier interleaved service data are multiplexed in one Mapped to the corresponding spectrum mode, the composition of the OFDM frequency domain symbols; An OFDM modulator for performing an IFFT transform to the time domain of the OFDM frequency domain symbol; an OFDM time domain symbol generator for multiplexing the OFDM modulator output with the cyclic prefix to form an OFDM time domain symbol; a frame constituting unit, configured to multiplex the OFDM time domain symbol and the beacon to form a physical layer frame structure; and a mapping and framing module, configured to map and frame the logical layer frame structure to form a physical layer frame structure; And a transmitter, configured to transmit the physical layer frame structure by baseband to radio frequency conversion.

The mapping and framing module includes: a time domain subframe allocator for mapping logical subframes to physical subframes; a time domain frame composing device, configured to form physical subframes into physical frames; And used to form physical frames into physical superframes.

In addition, the apparatus further includes: a multi-frequency coordinated operation control module, configured to specify a specific multi-frequency coordinated working sequence for the digital audio broadcasting system.

When the service data from the upper layer includes multi-layer service data with different priorities, the scrambler separately scrambles the multi-layer service data into a bit stream; the encoder separately encodes And the constellation mapper respectively performs constellation mapping on the encoded multi-layer service data bitstream to obtain a plurality of modulation symbols, and multiplexes the plurality of modulation symbols in the same constellation space according to a power loading manner to obtain layering. Modulation symbol.

The embodiment of the present invention further includes a digital audio signal receiving method in a digital audio broadcasting system, comprising the steps of: Sl, transforming a signal from a radio frequency into a baseband, capturing a baseband signal, performing timing synchronization and carrier synchronization; S2: performing physical layer frame structure frame to logical layer frame structure mapping on the synchronized signal; S3, performing frequency domain transform, channel estimation, and equalization on the logical layer frame structure; S4, performing solution constellation mapping, debit interleaving, and volume Product decoding, extracting system information; extracting service description information by de-constellation mapping, de-interleaving, convolutional decoding, and descrambling; solving sub-carrier interleaving, de-constellation mapping, LDPC decoding, and descrambling After that, the upper layer service data is extracted; S5, the service description information and the service data are sent to the upper layer.

The step of extracting the system information in the step S4 further includes extracting current subband nominal frequency point information included in the system information and spectrum mode index information used by the current digital audio broadcast signal.

In addition, the receiving method further includes the following steps: adjusting the receiving end frequency point setting according to the extracted current subband nominal frequency point information and the spectrum mode index information used by the current digital audio broadcasting signal, and completing the current digital audio broadcasting signal. Frequency center point synchronization in spectrum mode; and receiving data on all valid subbands in the current spectrum mode.

Corresponding to the receiving method, the present invention also provides a digital audio signal receiving apparatus in a digital audio broadcasting system, as shown in FIG. The method includes: a timing synchronizer for timing synchronization and acquisition of the received signal; a frequency offset estimator for performing frequency offset estimation on the signal on the timing synchronization; and a frequency offset compensator for using the frequency offset estimator The obtained frequency offset compensation back to the receiving letter No.; physical layer frame structure to logical layer frame structure inverse mapper, used to transform the physical layer frame structure into a logical layer frame structure by mapping. An OFDM demodulator for performing FFT transform on the synchronized signal by time domain transform to the frequency domain; a channel estimator for estimating the frequency domain channel by the discrete pilot; and a channel equalizer for the channel estimator The obtained channel parameter compensates the received frequency domain signal; the pilot and data extractor is configured to separately extract the service description information, the system information, the scattered pilot, and the service data subcarrier in the frequency domain according to the spectrum mode; Decomposing a subcarrier interleaver for deinterleaving a service data subcarrier; a constellation mapping inverse transformer for mapping service description information, system information, and constellation mapping symbols carried on a service data subcarrier a bit stream; a deciphering interleaver, configured to deinterleave the service description information inversely transformed by the constellation mapping and the system information bit stream; the decoder, the bit stream of the service data inversely transformed by the constellation mapping, and the bit interleaving After the service description information and system information are decoded; the system information parser is used to decode System information parsed; descrambler, the service data stream and service description information decoded descrambling.

Although the position of the physical layer frame structure to the logical layer frame structure inverse mapper in the present embodiment is after synchronization, it is not limited to those before the FFT, and those skilled in the art should know that it can be placed at any position before deinterleaving.

The receiving device may further include a frequency point and filter setting module, configured to use the current subband nominal frequency point information included in the system information parsed by the system information parser and the spectrum mode used by the current digital audio broadcast signal. Index information, adjust the receiver front-end frequency point setting, and complete the frequency center point synchronization in the current digital audio broadcast signal spectrum mode.

The invention adopts advanced coding and modulation mode in the FM frequency band to ensure efficient and reliable transmission of audio data; and adopts multiple code rates and modulation combinations, and has high flexibility, adaptable (~kbps) to high speed (~Mbps) Scope and scalability; and based on the spectrum characteristics of the existing FM band, a flexible spectrum mode is designed, which does not affect the existing analog FM broadcast signal, but also has spectrum scalability. The invention has flexible system transmission parameter configuration and can be applied to single frequency network and multi frequency network mode.

In addition, according to a further embodiment of the present invention, multi-frequency coordinated operation is supported, which can improve the spectrum utilization efficiency while improving the transmission characteristics under the fading channel.

Another embodiment of the present invention provides a flexible frame structure that enables low power reception and achieves controllable terminal cost and power consumption.

One of ordinary skill in the art can understand that all or part of the steps carried by the method of implementing the above embodiments can be completed by a program to instruct related hardware, and the program can be stored in a computer readable storage medium. When executed, one or a combination of the steps of the method embodiments is included.

Furthermore, each functional unit in various embodiments of the present invention may be integrated in one processing module In addition, each unit may exist physically separately, or two or more units may be integrated into one module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. The integrated modules, if implemented in the form of software functional modules and sold or used as separate products, may also be stored in a computer readable storage medium. The above-mentioned storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Claims

Rights request

A method for transmitting a digital audio signal in a digital audio broadcasting system, comprising the steps of:

51. The transmitting end converts the service data from the upper layer into a bit stream, and performs scrambling; then performs LDPC encoding on the scrambled service data bit stream; performs constellation mapping on the LDPC encoded service data bit stream; After the subcarriers carrying the service data, subcarriers are interleaved to form the interleaved service data subcarriers;

52. The transmitting end converts the service description information from the upper layer into a bit stream, and performs scrambling; then performs convolutional coding on the scrambled service description information bit stream; and performs bit-biting on the convolution-coded service description information bit stream. Interleaving; performing constellation mapping on the bit-interleaved service description information bit stream to form a service description information sub-carrier;

53. The transmitting end groups the physical layer system information into a system information bit stream according to a specific format, and then performs convolutional coding; performs bit interleaving on the convolutionally encoded system information bit stream; performs constellation on the bit interleaved system information bit stream Mapping, forming system information subcarriers;

54. Generate a discrete pilot in the frequency domain, and then multiplex the interleaved data subcarrier including the service data subcarrier, the constellation mapped service description information subcarrier, and the contiguous pilot subcarrier including the system information subcarrier. Mapping to a corresponding spectral pattern to form an OFDM frequency domain symbol;

55. The frequency domain OFDM symbol is transformed into a time domain by using an IFFT transformer, and the cyclic prefix is multiplexed to generate an OFDM time domain symbol;

56. multiplex the foregoing multiple OFDM time domain symbols together, and insert a beacon, and connect to a logical layer frame structure;

57. Mapping and framing the logical layer frame structure to form a physical layer frame structure;

2. The method according to claim 1, wherein the spectral mode comprises a class A spectral mode and a class B spectral mode; wherein the class A spectral mode comprises 8 subbands, and the subband nominal frequency is a ± (100 +) 50) W3⁄4 = 0,1,2,3 ; Class B spectrum mode consists of 7 subbands, the subband nominal frequency is ± * 10 ( fcJ = 0,1,2,3 , the subband bandwidth is 100KHz .

3. The method according to claim 2, wherein the spectrum mode comprises 39, and the correspondence between the spectrum mode index 1-39 and the subband occupied by the corresponding spectrum mode is as follows:

01 B4

02 A4A5

03 B3B4B5

04 A3A4A5A6

05 B2B3B4B5B6

06 A2A3A4A5A6A7 07 B1B2B3B4B5B6B7

08 A1A2A3A4A5A6A7A8

09 A3A4A5A6

10 B2B3B4B5B6

11 A3A4A5A6A7

12 A2A3A4A5A6

13 A2A3A4A5A6A7

14 B1B2B3B4B5B6

15 B2B3B4B5B6B7

16 A3A4A5A6A7A8

17 A1A2A3A4A5A6

18 B1B2B3B4B5B6B7

19 A2A3A4A5A6A7A8

20 A1A2A3A4A5A6A7

21 A1A2A3A4A5A6A7A8

22 B3B4B5

23 A3A4A5A6

24 B2B3B4B5

25 B3B4B5B6

26 B2B3B4B5B6

27 A2A3A4A5A6

28 A3A4A5A6A7

29 B1B2B3B4B5

30 B3B4B5B6B7

31 A2A3A4A5A6A7

32 B2B3B4B5B6B7

33 B1B2B3B4B5B6

34 A1A2A3A4A5A6

35 A3A4A5A6A7A8

36 A2A3A4A5A6A7A8

37 A1A2A3A4A5A6A7

38 B1B2B3B4B5B6B7

39 A1A2A3A4A5A6A7A8

The spectrum mode index 1-8 is a pure digital mode, the spectrum mode index 9-21 is a stereo FM simulating mode, and the spectrum mode index 22-39 is a mono frequency simulating mode; a spectrum mode index 1,3,5,7,10,14,15,18,22,24,25,26,29,30,32,33,38 are class B spectrum patterns, and the rest of the index is

Class A spectrum mode.

4. The method according to claim 1, wherein the step of mapping and framing the logical layer frame structure to form a physical layer frame structure is:

Sub-frame allocation mode 1: The four logical sub-frames are sequentially mapped into four physical sub-frames of one physical frame in the order of four logical sub-frames in one logical frame, and four The physical frame constitutes one physical superframe; or

Subframe allocation mode 2: The two consecutive logical sub-frames in the two consecutive logical frames are grouped, the logical sub-frames in the group are interleaved, and the set of interleaved logical sub-frames are mapped to 2 consecutive physical frames, 4 of which are composed of 1 physical superframe; or

Subframe allocation mode 3: The ith logical sub-frame in each logical frame of the group is sequentially mapped to the i-th physical group by using four consecutive logical sub-frames in the four consecutive logical frames. A signal frame, where i is 1, 2, 3 or 4, forming 4 consecutive physical frames, and 4 of the physical frames constitute 1 physical superframe.

A digital audio signal transmitting apparatus in a digital audio broadcasting system, comprising: a scrambler for performing bit stream conversion and scrambling on upper layer service data and service description information; and a system information constructor for using the physical layer The system information forms a system information bit stream according to a specific format;

An encoder, configured to encode an upper layer service data bit stream output by the scrambler, a service description information bit stream output by the scrambler, and a system information bit stream;

a bit interleaver, configured to perform bit interleaving on the encoded service description information bit stream and the system information bit stream;

a constellation mapper, configured to perform constellation mapping on bit-interleaved service description information, system information, and encoded service data;

a subcarrier interleaver, configured to perform interleaving on the subcarriers of the constellation-mapped service data; a frequency domain symbol generator, configured to interleave the discrete pilot, constellation mapped service description information, system information, and subcarriers The service data is multiplexed together and mapped to corresponding spectrum modes to form OFDM frequency domain symbols;

An OFDM modulator, configured to perform an IFFT transform on the OFDM frequency domain symbol to the time domain; and an OFDM time domain symbol generator for multiplexing the OFDM modulator output with the cyclic prefix to form an OFDM time domain symbol;

a time domain logic sub-frame multiplexer, configured to multiplex the OFDM time domain symbols with the beacon to form a physical layer frame structure;

a mapping and framing module, configured to map and frame the logical layer frame structure to form a physical layer frame structure; And a transmitter, configured to transmit the physical layer frame structure by baseband to radio frequency conversion.

6. Apparatus according to claim 5 wherein said spectral pattern comprises a Class A spectral mode and a Class B spectral mode; wherein the Class A spectral mode comprises 8 subbands and the subband nominal frequency is ± (100 + ⁵⁾ 0) ^· = 0,1, ² , ³ ; Β The spectral mode consists of 7 subbands with nominal frequency points of earned = 0, 1, 2, 3, and the bandwidth of the one subband is ₁₀₀ ΚΗζ.

7. The apparatus according to claim 6, wherein the spectrum mode comprises 39, and the correspondence between the spectrum mode index 1-39 and the subband occupied by the corresponding spectrum mode is as follows:

01 Β 4

02 Α4Α5

03 Β3Β4Β5

04 Α3Α4Α5Α6

05 Β2Β3Β4Β5Β6

06 Α2Α3Α4Α5Α6Α7

07 B1B2B3B4B5B6B7

08 A1A2A3A4A5A6A7A8

09 Α3Α4Α5Α6

10 Β2Β3Β4Β5Β6

11 Α3Α4Α5Α6Α7

12 Α2Α3Α4Α5Α6

13 Α2Α3Α4Α5Α6Α7

14 B1B2B3B4B5B6

15 Β2Β3Β4Β5Β6Β7

16 Α3Α4Α5Α6Α7Α8

17 A1A2A3A4A5A6

18 B1B2B3B4B5B6B7

19 Α2Α3Α4Α5Α6Α7Α8

20 A1A2A3A4A5A6A7

21 A1A2A3A4A5A6A7A8

22 Β3Β4Β5

23 Α3Α4Α5Α6

24 Β2Β3Β4Β5

25 Β3Β4Β5Β6

26 Β2Β3Β4Β5Β6

27 Α2Α3Α4Α5Α6

28 Α3Α4Α5Α6Α7 29 B1B2B3B4B5

30 B3B4B5B6B7

31 A2A3A4A5A6A7

32 B2B3B4B5B6B7

33 B1B2B3B4B5B6

34 A1A2A3A4A5A6

35 A3A4A5A6A7A8

36 A2A3A4A5A6A7A8

37 A1A2A3A4A5A6A7

38 B1B2B3B4B5B6B7

39 A1A2A3A4A5A6A7A8

The spectrum mode index 1-8 is a pure digital mode, the spectrum mode index 9-21 is a stereo frequency simulcast mode, and the spectrum mode index 22-39 is a mono frequency simulcast mode; the spectrum mode index 1, 3, 5, 7 , 10, 14, 15, 18, 22, 24, 25, 26, 29, 30, 32, 33, 38 are Class B spectral modes, and the remaining indexes are Class A spectral modes.

8. The apparatus according to claim 5, wherein the mapping and framing module maps and groups the logical layer frame structure to form a physical layer frame, specifically:

Subframe allocation mode 3: The ith logical sub-frame in each logical frame of the group is sequentially mapped to the i-th physical group by using four consecutive logical sub-frames in the four consecutive logical frames. Signal frame, where i is 1, 2, 3 or 4.

A digital audio signal receiving method in a digital audio broadcasting system, comprising the steps of: Sl, transforming a signal from a radio frequency into a baseband, capturing a baseband signal, performing timing synchronization and carrier synchronization;

S2: performing physical layer frame structure frame to logical layer frame structure mapping on the synchronized signal;

53. Perform frequency domain transform, channel estimation, and equalization on the logical layer frame structure;

54. Extracting system information by performing constellation mapping, de-interleaving, and convolutional decoding; extracting service description information by performing constellation mapping, de-interleaving, convolutional decoding, and descrambling;

After decomposing subcarrier interleaving, de-constellation mapping, LDPC decoding, and descrambling, the number of upper layers of services is determined. Extracted

S5. Send the service description information and the service data to the upper layer.

10. A digital audio signal receiving apparatus in a digital audio broadcasting system, comprising: a timing synchronizer configured to perform timing synchronization and acquisition on a received signal;

a frequency offset estimator for performing frequency offset estimation on the signal on the timing synchronization;

a frequency offset compensator for compensating the frequency offset obtained by the frequency offset estimator back to the received signal; a physical layer frame structure to a logical layer frame structure inverse mapper, configured to transform the physical layer frame structure into a logical layer frame structure by mapping .

An OFDM demodulator, configured to perform FFT transformation on the synchronized signal, and transform from the time domain to the frequency domain;

a channel estimator, since the frequency domain channel is estimated by discrete pilots;

a channel equalizer, configured to compensate the received frequency domain signal according to a channel parameter obtained by the channel estimator;

a pilot and a data extractor, configured to respectively extract service description information, system information, discrete pilot, and service data subcarriers in a frequency domain according to a spectrum mode;

Decomposing a subcarrier interleaver for deinterleaving a service data subcarrier;

a constellation mapping inverse transformer, configured to map the service description information of the frequency domain channel equalization, the system information, and the constellation mapping symbols carried on the service data subcarriers to the bit stream;

a bit interleaver for deinterleaving the service description information inversely transformed by the constellation mapping and the system information bit stream;

a decoder, which decodes the service data bit stream inversely transformed by the constellation mapping, the service description information after deinterleaving, and system information;

a system information parser, configured to parse the decoded system information;

The descrambler descrambles the decoded service data stream and the service description information.