CN101867446B - Method for transmitting and receiving broadcast signals and equipment for transmitting and receiving broadcast signals - Google Patents

Abstract

According to an embodiment of a method of transmitting a broadcast signal, a source stream including a plurality of frames composed of first data and second data regions is randomized using a specific code, the randomized source stream is channel-encoded to generate data blocks, a signal frame is generated from the generated data blocks, and the generated signal frame is transmitted. The randomization may be performed by at least one of a method of randomizing the data with a predetermined randomization period and a method of randomizing the data including the data having randomness in the second partial data area. Therefore, the invention not only can maintain the randomization algorithm (randomization algorithm) of the related specification, but also can improve the randomness (randomness) of the transmission signal, improve the randomness of the transmission signal, improve the receiving performance of the receiving end, and receive and process the random transmission signal and improve the efficiency of the system without any additional equipment at the receiving end.

Description

Method for transmitting and receiving broadcast signals and equipment for transmitting and receiving broadcast signals

technical field

The present invention relates to broadcast signal transmission and broadcast signal receiving equipment, more particularly in order to improve the performance of broadcast signal receiving equipment for receiving broadcast signals, thereby strengthening the broadcast signal transmission and reception method and broadcast signal transmission and reception of the randomness of the transmitted signal equipment.

Background technique

The specification proposed for China's terrestrial digital television broadcasting standard is called terrestrial digital multimedia/television broadcasting (Terrestrial Digital Multimedia/Television Broadcasting;), hereinafter referred to as DMB-T). In DMB-T, it is possible to call time domain synchronous orthogonal frequency multiplexing (time domain synchronous orthogonal frequency division multiplexing (OFDM) is TDS-OFDM, hereinafter referred to as TDS-OFDM) signal modulation technique, and single carrier modulation technology to transmit signal modulation technique Can be used selectively.

TDS-OFDM receiving end modulates the transmitted signal such as cyclic prefix OFDM (CP-OFDM below cyclic prefix OFDM) method on the signal transmitted by most subcarriers, inverse separation Fourier transform (Inverse DiscreteFourierTransform below IDFT) is applied (multi-carriermodulation) .

On the contrary, the transmission signal of DMB-T carries the signal on one carrier, and the modulation technique (single-carrier modulation) can be transmitted. That is, the DMB-T transmission signal, the signal obtained by multi-carrier modulation and the signal obtained by single-carrier modulation are multiplexed and transmitted. However, the multiplexed transmission signal is used as a training signal. In the guard interval (guard interval), it is not CP. Instead, an analog noise signal (pseudonoise; PN in the following) is inserted.

In the same manner as above, signal overhead during broadcast signal transmission can be reduced. Improve the efficiency of channel application, improve the power of broadcast signal receiving equipment and the performance of channel estimation section.

However, according to the traditional DMB-T method and the randomization algorithm of related specifications, the randomization reset period is short, and within this period, the probability that randomized zero packets will be uniformly distributed on the drawing is low, and the randomness (randomness) is reduced. question. There is also a problem that the randomness of the transmission signal is low, and the receiving performance of the receiving end is degraded. Furthermore, at the transmitting end, the change of the randomization algorithm according to the relevant specifications will bring a burden to the receiving end. On the receiving end. In order to compensate for the decrease in the randomness of the transmitted signal, it is necessary to increase the cost of equipment, which may bring about problems with the overall efficiency of the equipment such as specifications and sizes.

Contents of the invention

Issues to be solved

The present invention is to solve the above-mentioned problems. The purpose of the present invention is to maintain the randomization algorithm of the relevant specification signal, and provide a broadcast signal receiving and sending method and a broadcast signal transmission and receiving device that can improve randomness.

Another object of the present invention is to enhance the randomness of the transmitted signal, thereby improving the performance of the receiving end of the broadcast signal.

Another object of the present invention is to improve the efficiency of the system, that is, without adding any additional equipment at the receiving end, it can receive the above-mentioned highly random transmission signal well and process the signal effectively.

means of solving problems

The present invention relates to broadcast signal transmission and reception methods and broadcast signal transmission and reception equipment. According to the present invention, the embodiment of the broadcast signal transmission method includes a source stream of multiple frames composed of a first data area and a second data area using specific The stage of code randomization; the stage of generating data blocks by the above-mentioned randomized source stream channel coding; the stage of generating data frames in the above-mentioned generated data blocks; and the transmission stage of the above-mentioned generated signal frames. At least one method is used among the randomization of the randomization cycle randomization and the data randomization method including the randomness in the above-mentioned second data area.

At this time, the above-mentioned randomization unit can use a unit of at least two frames, a unit of a calendar day frame (CDF: calendar day frame), a unit of a minute frame (minute frame) and a unit of a super frame (superframe) as a predetermined random period. One for randomization.

In addition, the above-mentioned randomization unit, as the above-mentioned data having randomness, may have the same or non-overlapping data in each of the second data areas within at least one randomization cycle as the data having randomness. Contains PRBS-passed data.

According to an example of broadcasting signal transmission according to the present invention, a randomization unit that randomizes source streams of a plurality of frames composed of a first data area and a second data area using a specific code; said randomized source streams are channel-coded to form a channel of a data block An encoding unit; a generating unit that generates a signal frame from the generated data block; and a transmitting unit that transmits the generated signal frame; the randomizing unit uses a predefined randomization period to randomize the source stream and includes the second data At least one method is used among the data randomization methods with randomness in the region.

At this time, the above-mentioned randomization unit can use a unit of at least two frames as a predetermined randomization cycle, in a unit of a calendar day frame (CDF: calendar day frame), a unit of a minute frame (minute frame) and a unit of a super frame (superframe). One is randomized.

In addition, the above-mentioned random part, as the above-mentioned data having randomness, the data in the respective second data areas are all identical to each other or non-overlapping data in at least one randomization cycle, as the above-mentioned data having randomness. Includes random data via PRBS.

An example of the broadcast signal processing method according to the present invention includes a receiving stage of receiving a digital broadcast signal randomized using a specific code; and a stage of encoding the received digital broadcast signal. The digital broadcast signal includes the first data and the second data. A plurality of frames composed of the data area, at least one of the methods of randomization with a predefined randomization period in the above-mentioned middle randomization method and the randomization method including the randomness in the second data area mentioned above is used, and the above-mentioned encoding stage , is completed by the stage of identifying the above-mentioned second data area in the above-mentioned received digital broadcast signal, and the stage of controlling the identified second data area not to be re-encoded.

At this time, the above-mentioned predefined random period may be at least two frame units, one of a calendar day frame (CDF: calendar day frame) unit, a minute frame (minute frame) unit and a super frame (superframe) unit.

In addition, the above-mentioned random data may include data in which the data in the second data areas are identical or non-overlapping in at least one random period, and may include random data via PRBS.

In addition, the above-mentioned digital broadcast signal includes 420, 595, and 945 frame headers with at least one code symbol and information frames with a frame body of 3780 symbols. The above-mentioned frame body includes demodulation information, decoding information, symbol mapping mode, LDPC code rate, insertion mode information, frame body mode information and other corresponding signal information required for each signal frame. It can be realized by changing the above-mentioned 1st and 2nd data areas

An example of a broadcast signal processing method according to the present invention includes a receiving unit that receives a digital broadcast signal randomized using a specific code; an encoder that encodes the received digital broadcast signal; and a control unit that controls the encoding operation of the encoder; The digital broadcasting signal includes a plurality of frames composed of the first data and the second data area, the above-mentioned randomization is randomized with a predefined randomization period and includes the randomization of data in the second data area. At least one of the modes is used, the control unit identifies the second data area in the received digital broadcast signal, and controls the identified second data area not to be re-encoded.

At this time, the control unit controls the decoding of the received digital broadcast signal, and the predetermined random period of the digital broadcast signal may be at least two frames in units, a calendar day frame (CDF: calendar day frame) unit, One of minute frame (minuteframe) unit and super frame (superframe) unit.

In addition, the control unit controls the decoding of the received digital broadcast signal, and the above-mentioned data having the randomness of the digital broadcast signal, in at least one randomization period, the data in the second data areas are mutually identical or non-repetitive data, Random data via PRBS is also included.

In addition, the control unit controls the decoding of the received digital broadcast signal, and the digital broadcast signal includes an information frame having a frame header with a symbol having at least one code among 420, 595 and 945 and a frame body including 3780 symbols. , the above-mentioned frame body includes corresponding signal information such as demodulation information, decoding information, symbol mapping mode, LDPC coding rate, insertion mode information, and frame body mode information required for each signal frame. It can be realized by changing the above-mentioned 1st and 2nd data areas

Effect:

According to the present invention relates to a method for transmitting and receiving broadcast signals and a device for transmitting and receiving broadcast signals,

First, the randomization algorithm (randomization algorithm) of relevant specifications can be maintained, and the randomness (randomness) of the transmitted signal can be improved.

Second, the randomness of the above-mentioned transmitted signals is improved, and the receiving performance of the receiving end is improved, and thirdly, the receiving end does not need any additional equipment, which has the advantages of receiving highly random transmitted signals and improving processing efficiency.

Description of drawings

FIG. 1 is a diagram illustrating constituent symbols of a broadcast signal transmission device according to the present invention.

Fig. 2 to Fig. 4 are related to the present invention, in order to illustrate the generation of each sequence, illustrate linear feedback transfer

Structural (linerfeedbackshiftregister: LFSR, LFSR below) drawing

Fig. 5 is related to the present invention, illustrates the diagram of the scrambler coder (scrambler coder)

Figure 6 is a diagram illustrating randomized data packets repeated every cycle of a signal frame

Figure 7 is a diagram illustrating the effect of time-domain interleaving

Figure 8 is a diagram illustrating a method for improving randomization according to Example 1 of the present invention

Fig. 9 is in order to realize the example 2 of the present invention, illustrates the diagram of the composition of transmitter

Fig. 10 is a diagram of receiving a highly random transmission signal and processing it according to the present invention

Explanation of the main symbols

110: randomization unit 120: forward error correction unit 130: channel coding unit

140: system information output unit 150: multiplexing unit 160: frame body processing unit

170: Frame header output unit 180: Frame forming unit 190: Filtering unit

200: Transmission Department

The specific content of implementing the invention

Accordingly, with reference to the drawings of the additional method for transmitting broadcast signals and the actions of the device according to the present invention, the details are as follows:

According to the method for transmitting and receiving broadcast signals of the present invention, and for the description of the settings, the terrestrial digital television broadcast is taken as an example (terrestrial digital television broadcast) in this specification below for the convenience of explanation, especially the transmission of signals from China to terrestrial digital television broadcast The receiving method and equipment will be described as examples.

broadcast signal transmission equipment

FIG. 1 is an example of a configuration block diagram of a broadcast signal transmission device according to the present invention.

According to an example of the device for broadcast signal transmission of the present invention, it includes: random part (110) (randomization block), forward error correction part (120) (forward error correction (FEC) block), channel coding part (channelcoding (constellationmappingandinterleave) block) (130) , system information output unit (system information block) (140), multiplexing unit (multiplexer) (150), frame body data processing unit (frame body data processing block) (160), frame header output unit (frame header block) (170), frame formation unit (frame grouping block) (180), filtering part (filtering (baseband postprocessing) block) (190) and transmission part (transmitting (orthogonalup-convert) block) (200).

A detailed description of each frame section is as follows:

Randomization (110): Randomize the input source stream (sourcestream). At this time, the randomization process in the randomization unit (110) will be described in detail in the corresponding part according to the implementation of the method according to the present invention described later, and will be omitted here. Here, the source stream input to the random part (110) is, for example, a bitstream format (bitstream).

A forward error correction unit (120) performs forward correction (FEC) on a transport signal (transport signal) including a randomized input source stream. Here, forward error correction (FEC) can be implemented by linking outer code (outercode) and inner code (inner code) at the sending end for the convenience of correcting the transmitted broadcast signal at the receiving end. In addition, the above-mentioned outer code can use BCH (Bose-Chaudhuri-Hocquenghem), and the inner code can use LDPC (LowDensityParityCheck). At this time, the specific parameters (parameters) of the forward error correction (FEC) are, for example, the same as the table. 1

Table 1

Number code length (bit) information code Corresponding coding efficiency Code rate 1 7488 3008 0.4 Code rate 2 7488 4512 0.6 Code rate 3 7488 6016 0.8

BCH (762,752) is formed by shortening BCH (1023,1013), adding 0 to the first 261 bits of the 752-bit data scrambling code (bitdatascramblingcode) to form 1013 bits and encoding this, 1023 bits (information bits) in front . Afterwards, based on the previous 261-bit information, 0,762-bit information is added to form a BCH codeword. The mathematical formula 1 of the polynomial (polynomial) generated by the above-mentioned BCH codeword is as follows:

G _BCH (x)＝1+x ³ +x ¹⁰

Among the above code rates (coderate), for example, the same BCH code can be used for forward error correction (FEC).

Then, the structure of the generation matrix (generation matrix) Gqc of the LDPC code is, for example, the same as the following mathematical expression 2

Mathematical formula 2

Among them, 'I' is the bxb step unit matrix (stepunitmatrix), 'O' is the bxb step zero matrix (stepzeromatrix), G(i,j) is the bxb circulation matrix (circulationmatrix) 'i is greater than 0 and less than k-1,'j ' is greater than 0 and less than c-1.

When the BCH codeword is input into LDPC code (not shown) in order, the first bit (bit) is the first element (firstelement) of the information sequence vector (informationsequencevector), and the codeword information bit (bit) output by the above-mentioned LDPC encoder is in The latter is located in front of the check bit (checkbit), and the LDPC code generates a circulant matrix G(i, j). The forward error correction (FEC) structure of the above three different code rates (coderate) is illustrated as follows:

a), FEC(7488,3008) code with code rate 0.4:

First, 4 BCH (762,752) codes and 5 check bits in front of LDPC (7493, 3408) codes. The matrix Gqc of the LDPC(7493,3048) code has a matrix form as shown in (3), and the matrix parameters are k=24, c=35, b=127.

b), FEC(7488,4512) code with code rate 0.6:

First, 6 BCH (762, 752) codes are connected with LDPC (7493, 4572) codes, and then the 5 check bits in front of (7493, 4572) are deleted. The matrix Gqc of the LDPC(7493, 4752) code has a matrix form as shown in (3), and the matrix parameters are k=36, c=23, b=127.

c), FEC (7488, 6016) code with a code rate of 0.8:

First, 8 BCH (762,752) codes are connected with LDPC (7493,6096) codes, and then the 5 check bits in front of the LDPC (7403,6096) codes are deleted. The generator matrix Gqc of the LDPC (7493, 6096) code has a rectangular form shown in formula (3), wherein the parameters are k=48, c=11, b=127.

The channel coding unit (130) performs channel coding (channel coding) on the above-mentioned forward error correction transmission signal, where the channel coding can be realized by symbol mapping (symbol mapping), interleaving (interleaving) and so on. The above symbol mapping is a constellation mapping (constellation mapping) from a bit stream (bitstream) to a symbol stream (symbol stream) after forward error correction. That is: uniform nQAM (Quadrature Amplitude Modulation, Quadrature Amplitude Modulation), (here n the number of constellation points) means the transformation to symbol stream (symbol stream), and in addition, it includes most symbol mapping relationships in related specifications. Such symbol mapping relationships may include 64QAM, 32QAM, 16QAM, 4QAM and 4QAM-NR. Power normalization is applied to most of the above-mentioned symbol maps, so that the power of multiple symbol maps is almost the same. For example, every 6 bytes of the 64QAM modulation image input bit stream corresponds to a constellation symbol (constellation symbol). Every 5 bytes of the 32QAM modulation image input bit stream corresponds to a cluster code, every 4 bytes of the 16QAM modulation image input bit stream corresponds to a cluster code, and every 2 bytes of the 4QAM modulation image input bit stream corresponds to a cluster code. Cluster code corresponding. In addition, 4QAM-NR refers to adding or applying NR orthogonal coding mapping (Nordstrom Robinson (NR) nearorthogonalencodingmapping) before the above-mentioned 4QAM symbol mapping. The channel coding unit (130) interleaves symbol streams formed after symbol mapping to form symbol units. Because the interleaving of symbol units here is time domain interleaving encoding (time domain interleaving encoding) can be performed in basic data blocks (data blocks) of multiple symbol frames (symbol frames). For example, the interleaving between basic data blocks of a data signal (that is, cluster symbols of a data code (datacode)) may utilize cluster symbol-based convolutional interleaving coding (convolve interleave encoding).

A system information generating unit (140) generates system information of a transmission signal including information on the structure of the transmission signal or channel coding. Here, the system information (system information), for example, may include information about the inner code rate (inner code rate), modulation type (modulation type), and interleaving mode (interleaving mode) of the transmission signal.

The multiplexing unit (150) multiplexes the signal obtained by channel coding and the output system information.

A frame body processing unit (160) processes a frame body signal transmitting broadcast data of an input signal multiplexed by a multiplexing unit (150). Here, the frame body processing unit (160) can separately process the signals in the frame of the input transmission signal using two modulation methods defined in accordance with the relevant standards. One is a single carrier modulation scheme (singlecarrier (SC) modulation scheme), and the other is a multicarrier modulation scheme (multicarrier (MC) modulation scheme). Single-carrier modulation (SCmodulationscheme) is similar to ATSC (8-VSB) in the United States. Based on high bit speed and superior performance, it can be used for fixed HDTV (HDTVHighDefinitionTelevision). The multi-carrier modulation scheme (MCmodulationscheme) according to the present invention is similar to the prefix orthogonal frequency multiplexing scheme (CyclicPrefix(CP)-OFDM(CP-OFDM)). Here, according to the transmission data of the above-mentioned multi-carrier modulation method, the inverse discrete Fourier transform is used, the guard interval is not a CP but the pseudo-random noise sequence (Pseudo-random Noise (PN) Sequence (PN)) is used for the training sequence (training sequence ), therefore, the above-mentioned multi-carrier modulation scheme (MCmodulation scheme) can not only reduce the transmission overhead and improve the channel performance, but also can improve the motivation processing of the receiving end and the performance of the channel estimation unit.

A frame header output unit (170) outputs a frame header signal used as a training sequence (training sequence) of a transmission signal. In the present invention, it is assumed that a PN sequence is used as the above-mentioned training signal as an example. Frame header output unit (170) generates PN sequence according to certain rules

The frame forming part (180) multiplexes the output of the frame body processing part (160) and the output of the frame header generating part (170) to form a date frame structure. Here, the structure of the data frame may form, for example, a four-layer structure. In addition, the basic unit of the structure of the above-mentioned data frame is a signal frame (signal frame). A signal frame consists of a frame header and a frame body. A superframe is defined as a group of signal frames. A minuteframe is defined as a set of superframes. In addition, the top layer (toplayer) of the above data frame is called CDF (CalendarDayFrame). Here, a signal frame (signal frame) is a basic unit of system frame construction, and is composed of a signal frame, the above-mentioned frame header and the time-domain signal of the frame body. Different structures can be formed according to the formation of the above frame header. In addition, the signal baseband signal ratio (basebandsymbolrate) of the frame header and the frame body, for example, can be

is the same value as 7.56MHz.

The frame header is composed of PN sequence, and there are 3 modes. FIG. 2 and FIG. 4 are related to the present invention. For the generation structure of each sequence, the linear feedback shift register sequence structure diagram (linear feedback register (LFSR) is referred to as LFSR) is taken as an example. The following is a more specific description with reference to FIGS. 2 and 4 .

First, the PN sequence adopted by the frame header mode (Frameheader mode) is defined as an 8-step m-sequence (8stepmseqence (8 dry times)) of the click extension (CyclicExtension). It can be implemented with an LFSR, with '0'+1 value (value), '1'-1 value (value), binary symbol mapping conversion.

A frame header signal (frame header signal, PN420) with a length of 420 symbols is composed of a signal header (pre-amble), a PN255 sequence and a signal tail (post-amble). The above-mentioned signal header and signal tail are defined as a single-click extension of the PN255 sequence, wherein the length of the signal header is 82 symbols, and the length of the signal tail is 83 symbols. The initial conditions of the LFSR determine the phase of the generated PN sequence. There are 255 signal frames in a super frame, and in each super frame, the frame header of each signal frame adopts different phase PN signals to form a signal frame link (frametag).

The generator polynomial of the LFSR that generates the sequence PN255, for example, can be expressed with the following mathematical formula 3:

Mathematical formula 3

G(x)＝1+x+x ⁵ +x ⁶ +x ⁸

The PN420 sequence can generate the LFSR shown in Figure 2. When referring to Fig. 2, based on the initial state of the LFSR, 255 mutually different phase PN420 sequences can be generated, and the sequence numbers are from 0 to 254. In the present invention, 225 phase PN420 sequences are selected, and the sequence is from 0 to 224 . The present invention selects 225 PN420 sequences among them, and the sequence number is from 0 to 224. When each super frame starts, the LFSR resets (reset) back to the initial state where the sequence number is 0.

The average power of the frame header signal is twice that of the frame body signal. In addition, the phase change of the PN sequence may not be implemented if the frame sequence number is not required to be displayed, and the initial phase with the sequence number 0 is used.

Next, Frame header mode 2 (Frame header mode 2) adopts the longest PN sequence of 10 steps, and the length of the frame header signal is 595 symbols, that is, there are 595 symbols in front of the m-sequence (msequence) with a length of 1023. The longest PN sequence generates a 10-bit (bit) shift register group (shiftregistergroup). The specific generated polynomial is the same as Mathematical Formula 4:

Mathematical formula 4

G ₁₀₂₃ (x)＝1+ ^x3 + ^x10

The initial phase of the 10-bit shift register group is 0000000001, and each signal is reset at the beginning.

Refer to Figure 3 for the structural diagram of generating the longest PN sequence. When referring to Figure 3, the 595 codes before the PN sequence are converted to symbol mapping with '0'+1 value, '1'-1 value, and binary method. In this case, a super frame includes 216 information frames in total, and in each super frame, the frame header of each information frame may adopt the same PN sequence. The average power of the frame header is the same as the average power of the frame body signal.

Finally, the frame header mode 3 adopts the PN sequence of (Frameheadermode3), which is defined as a 9-step m sequence extended by clicking. It can be realized by an LFSR, with '0'+1 value, '1'-1 value, binary symbol mapping conversion.

The frame header signal (PN945) with a length of 945 symbols is composed of an information header, a PN511 sequence and an information tail. The above information header and information tail are defined as the single-click extension of the PN511 sequence, and the length of the above information header and information tail is 217 symbols. The initial conditions of the LFSR determine the phase of the generated PN sequence. A super frame has 200 signal frames in total, and the frame headers of each signal frame in each super frame use PN signals with different bits as signal frame marks.

The polynomial of the LFSR that generates the sequence PN511 is defined as the same as the mathematical formula 5 in the figure below.

Mathematical formula 5

G ₅₁₁ (x)＝ ¹ + ^x2 + ^x7 +x8+ ^x9

The PN945 sequence can generate the LFSR of Figure 4. Referring to Figure 4, based on the initial state of the LFSR, 511 different PN945 sequences can be generated, with sequence numbers ranging from 0 to 510. In the present invention, 200 PN945 sequences are selected, and the sequence numbers are 0 to 199. At the beginning of each super frame, the LFSR resets back to the initial phase with the sequence number 0. In addition, the average power of the frame header signal is twice the average power of the frame body signal. And in the case where the frame sequence number is not required to be displayed, the phase change of the PN sequence may not be realized, and the PN initial phase with the sequence number 0 may be used.

As mentioned above, the frame header signal has 3 modes, and in this specification, the frame header signal adopts the same 4QAM modulation of I and Q. In addition, the frame body includes 36 symbol system information and 3744 symbol data, a total of 3780 symbols. The duration of a super frame is defined as 125ms, and 8 super frames are 1 second. Therefore, a time system (for example: GPS) is convenient when checking the time. The duration of a minute frame is 1 minute, including 480 super frames. The CDF repeats in a natural cycle, consisting of 1440 periods of 24 hours.

As mentioned above, the basic unit of the data frame structure is the signal frame. The signal frame is composed of frame header and frame body. In order to be suitable for different operation modes, it is defined as the signal frame structure corresponding to the three action frame header modes. Therefore, with the difference of the frame headers of the above three types of action frames, the number of signal frames of the formed super frame is also different.

The filter unit (190) filters the signal bandwidth (bandwidth) generated by the frame forming unit (180), that is, forms an output signal (for example, 8 MHz bandwidth) through baseband post-processing (baseband post-processing). For example, the above-mentioned baseband post-processing (baseband post-processing) uses SRRC (Square Root Raised Cosine) filtering to perform pulse correction on the baseband, which can prevent inter-symbol interference. At this time, the rolloff factor (rollofffactor:α) of the above SRRC filter is 0.05.

Moreover, the transmission part (200) performs orthogonal up-conversion processing (orthogonal upconversion) on the signal output by the filter part (190) to form a radio frequency signal of RF (Radio Frequency) with a periodic wave number fc (center frequency), and the transmission bandwidth is, for example , UHF (ultra high frequency) VHF (very high frequency radio frequency band) can be used to transmit signals in the RF bandwidth of the periodic wave number band range.

Randomization

There is a correlation between the transmitted data, and this correlation can affect the transmitted signal and generate useless signals. Therefore, it is highly desirable to de-correlate such signals. One of the methods to eliminate the interrelationship between signals is randomization. The purpose of randomization is to prevent the transmission of useless signals. Therefore, the formation of randomization can eliminate the correlation between data and prevent the transmission of useless signals. Improve the receiving performance of the receiver. That is, by eliminating the correlation between the transmitted data through randomization, the power spectrum pattern (power spectrum) of the transmitted signal of the receiver can also be basically predicted, the shape of the timing recovery circuit in the receiver (timingrecoverycircuit), automatic gain The transmission data in the control circuit (automatic gain control circuit) and other adaptive circuits are relatively effectively processed to improve the overall performance of the receiver. In addition, such randomization also satisfies the regulations of, for example, the Federal Communications Commission (FCC: federal communications commission) and the electromagnetic compatibility (EMC: electromagnetic compatibility) certification institution (certification institution).

Below is the attached reference image for the randomization method.

Fig. 5 is the picture surface that an example of the relevant scrambler code (scramblercoder) of the present invention pours into

As described above, it is necessary to confirm the randomness of transmitted data at the transmitting end. The following is an example of randomizing the transmitted data (streamdata) into a scrambling code (scrambling code) method according to the relevant specifications. Here, the scrambler using pseudo-random binary sequence (PRBS) is used as an example in this specification.

In FIG. 5, the structure of the scramling code related to the present invention is introduced as an example. The transmitting/receiving end of the broadcast signal uses a pseudo-random binary sequence (PRBS) due to interference signals, and the above-mentioned sequence (PRBS) can generate LFSR.

The polynomial of LFSR is as in mathematical formula 6, and the initial state can be defined as 100101010000000.

Mathematical formula 6

G(x)＝ ¹ + ^x14 +x15

According to the input type bit stream (bitstream) and PN sequence (PNsequence pseudo-random code), the data scrambling code (datascreamling code) is generated after adding the second bit modulus (modulotwoaddition).

Randomization reset period (Randomization reset period)

The linear feedback shift register (LFSR) of the scrambler coder (scrambling coder) in the related specification expressly resets back to the initial state (initial phase) at the beginning of each signal frame (frame). That is, every frame body, the linear feedback shift register is reset periodically. The above-mentioned one frame body here is, for example, 3744 symbols (symbol), and the above-mentioned symbol means a data unit formed by constellation mapping (constellation mapping) of a QAM mode type (mode). However, the data before the above cluster mapping is the data that has undergone forward error correction, that is, with different code rates, the number of bit stream data (streamdatabit) in each frame is also different. For example, Table 2, Table 2 shows the random cycle reset(randomizationresetperiod)

Table 2

randomness

FIG. 6 is a diagram for explaining randomized zero-packet introduction repeated every signal frame period.

As described above, in the present invention, randomization is realized by resetting in units of one signal frame. According to the mode of invention, in order to illustrate randomness (randomness) according to randomization, illustrate as follows: Assume that there are about 32Mbit/sec (here, 64QAM, code rate (coderate))=0.8. signal frame length (singalfreamlength)=4200 A case where the transmission stream (TS) data rate is 4 Mbit/sec in a system (see Table 3 to be described later) with a payload (payload) of . Here, zero packets are inserted during 28 Mbit/sec excluding the TS data rate of 4 Mbit/sec out of 32 Mbit/sec. The above zero packet is composed of a header area (header area) and a data area (data area) (for example: 184 bytes). The header area (header) is identified as a flag of the data packet, that is, whether the packet is a zero packet, and there is no restriction on the above data area. In addition, for example, all '1' or '0' are inserted in the above-mentioned data area.

As mentioned above, if zero packets are inserted, the TS data packets occupying 1/8 of the overall signal frame (the shaded part in Figure 6), although each frame is randomized, in the above overall frame, the remaining part of the TS data is excluded (7/8 of the overall information frame) zero packets (A, B, C in Fig. 6) are randomized into unified data, and repeated for each data frame (refer to Fig. 6). Here, if the zero packets occupying 7/8 of the overall signal frame are not evenly distributed according to 64 constellation points (constellation points), but are all gathered at special points, the probability of each information frame being distributed at a specific point will increase. Big. This is a phenomenon where the degree of randomness is reduced evenly distributed over 64 cluster points. Such phenomenon along with the TS data rate (TSdatarate) of transmission signal relative system data load capacity (payload) is little (that is, along with the increase of zero packet), the increase of cluster point that should be evenly distributed (that is, high-order QAM pattern ( higherQAMmode)), the probability of occurrence becomes larger. Table 3 shows the data rate (payloaddatarate) (Mbit/s) of the system load.

table 3

Time domain interleave (Timedomain interleave)

Figure 7 is a diagram inserted to illustrate time-domain interleaving

The purpose of time domain interleave encoding (Timedomain interleave encoding) is to interleave symbols within a plurality of signal frames, so that burst errors (burst errors) occurring during interleaving become obvious. It is just because the interleaving in the time domain has no effect on the distribution probability of a specific cluster point in units of symbols. Referring to Fig. 6, it can be found that although the positions of the symbols change, the interleaving of the symbol units does not change the whole symbols, so it has no influence on the distribution of the cluster points.

If, as mentioned above, instead of symbol interleave encoding (symbol interleaveencoding), bit interleave encoding is performed, due to the overall change of the symbol value (bitinterleaveencoding), the zero packet fixed at a specific point in a frame will carry a changed symbol value The position changes over multiple frames, creating randomness.

As mentioned above, the randomization reset period (randomization reset period) of related specifications is relatively short compared with other broadcast specifications in one frame (about 600us). In other words, the probability that the overall cluster points are uniformly distributed within a randomized reset period is relatively low. If the data rate of the transmission signal TS is short relative to the data rate of the system payload (payload daterate), the proportion of inserting a specific pattern of zero packets becomes larger, and the zero packets of each frame are repeated. If a frame's randomized null packets are not uniformly distributed over the overall rendezvous, then the possibility of centralized transmission from a particular rendezvous becomes greater. This becomes larger as the cluster points that should be uniformly distributed are a plurality of higher order QAM (higher order QAM mode) modes. In addition, the time interleaving (timeinterlever) which can improve randomness operates in symbol units due to the change of the data position does not affect the distribution of cluster points, so the random distribution does not change.

As a result, it is difficult to perform randomization according to the randomization algorithm defined in the relevant specification to solve the problem in symbolic units in order to increase the randomness. Therefore, in order to solve the above-mentioned problems, the following embodiments are used to prevent low randomness and improve the performance of the receiving end.

1st embodiment

Fig. 8 is a diagram introduced for the method of improving randomness according to the first embodiment of the present invention.

Referring to FIG. 8 , according to Example 1, it is an example of changing and expanding (hereinafter referred to as expanding) randomization weight synchronization (randomization reset period) method.

Because it is related to the randomization reset period, each information frame has a random reset period, and the randomization is low, which may affect the receiving performance.

Therefore, the present invention proposes a scheme of expanding the randomization period.

Below is a more detailed description of examples according to the present invention

FIG. 8( a ) is a case where the randomization reset period is one signal frame, and FIG. 8( b ) is a drawing introduced to explain the case where the randomization reset period is extended (two signal frames) according to the present invention. Here, referring to FIG. 8( a ) and FIG. 8( b ), the shaded part of each information frame represents TS data, and the remaining part represents zero packets. In addition, A, B, C, D, E, and F of the above-mentioned zero packets represent cluster points. Therefore, for the convenience of illustration, in FIG. 8 , a case where one frame has 7/8 zero packets is taken as an example. 8(a) The randomization period is 1 signal frame, that is, 3276 symbols out of a total of 3744 symbols are zero packets, 8(b) The randomization period is 2 signal frames, that is, 7488 (3744*2) symbols There are 6552 (3276*2) signals in the case of zero packets.

Referring to 8(a) and 8(b), the 3276 symbols in the zero packet of Fig. 8(a) are evenly distributed over 64 cluster points, compared to the 6552 symbols in the zeros of Fig. 8(b) in 64 clusters Evenly distributed points have a higher open rate. For example, in Figure 8(a), when the randomized reset period is an information frame, the randomized reset period is clustered on the zero packet A, B, and C3 cluster points, and the randomized reset period in Figure 8(b) is In the case of 2 frames, the distribution of randomized zero packets is more diverse than that of the 6 cluster points (A, B, C, D, E, F).

As a result, the frame reset period is more likely to be randomized than 1 frame unit to form a larger cycle. Only compared with the unlimited expansion of the frame reset period, according to the strength of the transmitted and received signals, the degree of randomization and the efficiency of the system are determined by the expanded frame unit, which can be appropriately defined. For example, it can be set as a super frame unit, a minute frame unit, and a CDF (calendar day frame) unit.

2nd embodiment

According to the present invention, as the second embodiment of the method for improving randomization, the data contained in the data field of the zero packet is not specific data, but random data. The so-called randomness data here means, for example, data that is identical or non-repeated and different from each other for every zero packet. In addition, the above-mentioned data with randomness, the same or non-repeated data in one frame period, at least in the above-mentioned one randomization period, based on one zero packet, is the same or not repeated with adjacent zero packets .

Fig. 9 is a diagram cited for realizing the second embodiment according to the present invention and explaining the constituent elements of the conveyor. Here, in FIG. 9, according to the present invention, in the transmitter, the receiving destination components after the randomized units are not shown in the figure, but are the same as the above-mentioned structure in FIG. 1, and the description of the randomness of each component is also originally used in the figure. 1 Description.

The randomized zero packet is repeated every time the randomization is reset. Here, take the data-specific data contained in the data area of the above randomized zero packet as an example, such as '1' and 'o', the same data repeats included in the data area. In the general TS data unit area, as the randomization reset period is different, each frame of the corresponding whole data is also different. Because of the randomness, there is no randomness problem. In the end the problem of randomness is mainly due to zero packets. In order to solve this problem, there may be many methods, but for the convenience of illustration, the data in the data area of the randomized zero packet is similar to the TS data in the present invention by using each randomized reset cycle, so that it has a random The sexual method is illustrated as an example.

The basic concept in Example 2 is as described above, making null packets as random as TS packets. There are certain regulations on the header area that constitutes the zero packet according to the relevant specifications, but there are no specific regulations on the data area. In order to meet the above standard conditions and prevent low randomness, the data contained in the above data area are identical or non-repetitive, including random data with randomness, and the randomness similar or identical to TS data is determined.

In the present invention, for the convenience of description, the data contained in the zero packet data area uses the random data passing through PRBS as an example, that is, the multiplexing of zero packets between the transmission streams at the sending end, in order to form a randomized source flow. At this time, the zero-packet data area is constituted by randomized data and convolutions through the PRBS. Therefore, in Fig. 1, the source stream input by the randomization unit is passed through the zero packet and the PRBS randomized data, convoluted data and multiplexed transmission data blocks to form data in the form of a bit stream. The present invention is not limited to the above-mentioned examples. It is also discovered in advance that the data in the above-mentioned data area is formed and used in other ways, and the random data with randomness is included in the scope of rights of the present invention.

According to the second embodiment of the present invention, as the data area for counting zeros, using randomness data can not only improve the performance of randomness, but also process the traditional zero packets of the receiver in the same way, and can also determine and conventional Receiver interchangeability. Because basically, in the processing of the zero packet, the receiver judges according to the corresponding packet. If the corresponding packet is a zero packet, it will be ignored and will not be decoded. Therefore, even if the data in the zero packet data area replaces traditional and other random data with randomness, the action of the receiver will not change. That is, to transmit the convolution code of the random data convolution (convolution) zero packet generated by the PRBS generator and the slave generator, only the convolution code is added. Even without any additional devices, the receiving end can process highly random transmission signals.

third embodiment

The third embodiment of the present invention is a combined embodiment of the first embodiment and the second embodiment described above. The randomization period is changed as in the stated embodiment 1, and the embodiment with randomized data is used as in the embodiment 2 in which data of zero packets in each frame are randomized within the stated randomization period.

According to the above-mentioned embodiments, as stated, the randomness of the transmitted signal is enhanced, and the transmitted signal with enhanced randomness can be received and processed without adding any additional device on the receiving end.

Receiving end

FIG. 10 is a diagram introduced according to the present invention to illustrate the structural framework of the receiving end for receiving and processing highly randomized transmission signals. Each frame of the receiver performs the same actions as the following, and the same as the above, receiving the characteristic Chinese terrestrial DTV broadcast signal processed at the receiving end.

Referring to FIG. 10 , the broadcast receiver includes: a tuning section (tuner) (701), an automatic acquisition control (autoagaincontroller: AGC) section (702), an AD conversion (analog/digital converter; ADC) (703), and a baseband processing (basebandprocessingblock) section (704), resampling (resampler) department (705), monitoring and frequency management department (SRRC: SquareRootRaisedCosine) (706), carrier recovery department (carrierrecoveryblock) (707), time recovery department (timingrecoveryblock) (708), data Processing section (dataprocessing block) (709), PN correlator (PNcorrelator) (710), channel estimator (channelestimator) (711), Fourier transform section (FFT: FastFourierTransformblock) (712), channel equalization section (channelequalizationblock) (713) , time deinterleaving section (timedeinterleaver) (714), storage section (715), symbol demapping section (symboldemapper) (716), LDPC decoding (LDPCdecoder) (717), BCH decoding (BCHdecoder) (718), descrambler (descrambler) (719), and control (720). A/V decoding(721)

The respective frames constituting the receiving end are explained as follows with reference to FIG. 10 attached below:

The tuning part (701) tunes the channel, and converts the transmitted RF frequency band signal (450Mhz-860Mhz) into a baseband through the tuned channel. The automatic acquisition control unit (AGC) (702) performs power normalization in order to recognize a fixed large signal of the A/D converter (703). AD conversion (ADC) (703) converts the input similar signal into a digital signal. The baseband processing unit (704) removes the frequency offset caused by the change of the digital signal. The re-sampling unit (705) is a crystal frequency offset of the signal after the frequency offset is removed. The monitoring and frequency management unit (706) restores it to an RC signal through the same SRRS as that of the transmitting unit.

The carrier recovery unit (707) estimates (estimating) and compensates (compensate) the frequency offset (frequency offset) of the incoming signal. The time recovery unit (708) estimates and compensates for the mutual offset (timing offset) of crystal (crystal) time. The data processing unit (709) eliminates ACI (adjacent channel interference) and CCI (co-channel interference). The PN correlator (710) is to find out the correlation coefficient (correlation coefficient) between the frame header (frame header) and PN. The channel estimator (711) is a method for estimating a wireless channel (wireless channel). The Fourier transform part (712) is to convert the data and estimated channel into (FFT) frequency domain (frequency domain) for equalization.

The channel balance unit (713) de-filters the estimated channel (de-filtering) to find data. The time deinterleaving unit (714) interleaves decoding of the coded signal (interleave encoding). The storage unit (715) temporarily stores the decoded signal (decoding) in the temporal deinterleave unit (714). The symbol demapping unit (716) demaps the symbol mapping (mapping symbol) transmitted according to the QAM mode type into LDPC symbols. The LDPC decoder (717) decodes the LDPC codeword into a BCH codeword according to the LDPC code rate (coderate), and the BCH decoding (718) decodes the BCH codeword into a coded bit stream (scrambling coded bitstream). The descrambler (719) descrambles the randomized symbol bit stream (scrambling coded bit stream) to make it into a data stream. And A/V decoding (721) is to receive the descrambled data stream in (719) and perform decoding.

Here, according to the invention, randomized zero packets, regardless of whether the corresponding packets are zero packets, can also be demodulated at the receiving end. That is, the randomized zero packet contained in the received data information performs channel equalization, signal demapping, LDPC decoding, BCH decoding and descrambling together with other data. Afterwards, perform the randomization zero packet in the digital signal until the descrambler, identify whether it is a corresponding zero packet (nullpacket) in the control part (such as system decoding) (720), and in the A/V (721) Make the above randomized zero packets no longer decoded. Therefore, in the example of the present invention described above, it can be realized by extending the reset period of zero packet randomization or even without changing the zero packet data area into temporary randomized data and without adding any additional equipment on the receiving end.

In a rough outline, the tuner unit (701) receives digital signals. The digital signal here may have a signal frame as described above. The above-mentioned signal frame is generally divided into a frame header (frame header) and a frame body (frame body). As stated above, the frame header has at least one of the 3 symbols. The above can have a first length of 420 symbols, a second length of 595 symbols, and a final length of 945 symbols. From the transmitting end, the decoding information (demodulation information), symbol mapping (symbol mapping method), insertion mode information (interleave mode information), LDPC decoding rate (coderate), frame body information (frame body information mode) required for each signal frame (signal frame), and their corresponding Information frame (signalframe) information is sent to the frame body. The signal frame is then changed into a data packet (datapacket) and a zero packet (nullpacket) at the transmitting end. Zero packets are randomized starting from the PRBS processor at the transmitting end. In the receiver, decoding processing including inverse randomization processing, digital signal processing is performed under LDPC decoding.

Therefore, according to the present invention. The traditional randomization calculation maintains the interchange line without changing, prevents the randomization of the transmitted information from being low, and improves the receiving performance. According to the present invention, the receiving end can receive and process highly random broadcast signals even without adding any equipment.

Claims (14)

1. the method sending broadcast singal, said method comprising the steps of:

Using particular sequence that the source stream comprising multiple frame is carried out randomization, the most each frame includes the first data field and the second data field；

Outer code and ISN is used to carry out forward error correction FEC coding to through randomized source stream；

Data block is generated with output symbol stream and intertexture by bit stream being carried out cluster mapping after FEC encodes；

Signal frame is generated based on the data block generated；

Send the signal frame that generated, wherein by using the method for randomization corresponding with predefined randomization period or carrying out randomized method perform described randomization to being included in the data in described second data field with randomness.

Method the most according to claim 1,

Wherein, described source stream is carried out randomized step to include:

By utilizing any one in unit, calendar day frame CDF, minute frame and the super frame more than at least 2 frames of described predefined randomization period that described source stream is carried out randomization.

3. according to the method one of claim 1 and 2 Suo Shu,

Wherein, the above-mentioned data with randomness are corresponding with data below:

Mutually the same data in each second data field or unduplicated data at least one random period,

Further, the above-mentioned data with randomness include the randomization data through PRBS.

4. sending a device for broadcast singal, described device includes:

Randomization unit, it is configured with particular sequence and the source stream comprising multiple frame is carried out randomization, and the most each frame comprises the first data field and the second data field；

Coding unit, it is configured with outer code and ISN and carries out forward error correction FEC coding to through randomized source stream；

Channel encoding unit, it is configured to that after FEC encodes bit stream carries out cluster mapping and generates data block with output symbol stream and intertexture；

Frame signal generating unit, its data block being configured to based on being generated generates signal frame；

Transmitting element, it is configured to send the signal frame that generated, wherein by using the method for randomization corresponding with predefined randomization period or the data being included in described second data field, having randomness are carried out randomized method performing described randomization.

Device the most according to claim 4,

Wherein, above-mentioned randomization unit carries out randomization for any one in units more than at least 2 frames of predefined randomization period, calendar day frame CDF, minute frame, super frame to described source stream also by utilizing.

6. according to the device one of claim 4 and 5 Suo Shu,

Wherein, above-mentioned randomization unit also carries out randomization to the following data with randomness: described in there are the mutually the same data in data second data field each with at least one random period of randomness or unduplicated data are corresponding and include the random data through PRBS.

7. the method processing digital broadcast signal, said method comprising the steps of:

Particular sequence is used to receive through randomized digital broadcast signal；And

By using ISN and outer code to decode received digital broadcast signal；

Wherein, described digital broadcast signal includes each frame containing the first data field and the second data field, wherein by using the method for randomization corresponding with predefined randomization period and at least one method of carrying out in randomized method to the data being included in described second data field, having randomness to carry out digital broadcast signal described in randomization

Wherein decoding step includes,

Described second data field is detected from received digital broadcast signal；And

The second data detected by control are not decoded.

Method the most according to claim 7,

Wherein, for any one in units more than at least 2 frames of above-mentioned predefined randomization period, calendar day frame CDF, minute frame, super frame, described digital broadcast signal is carried out randomization by utilization.

9. according to the method one of claim 7 and 8 Suo Shu,

Mutually the same data in described data second data field each with at least one random period with randomness or unduplicated data are corresponding and include the random data through PRBS.

Method the most according to claim 7,

Wherein, above-mentioned digital broadcast signal includes

At least provided with the frame head of symbol of a code in the frame originating point information of a length of 420,595,945 symbols, and the information frame of the frame with 3780 symbols,

Wherein, above-mentioned frame includes: the every demodulating information of information frame needs, decoded information, symbol mapping mode, LDPC code rate, intercalation model information, the relevant signal information of frame pattern information, further, described frame converts from above-mentioned first data field and the second data field.

11. 1 kinds of devices processing digital broadcast signal, described device includes:

Receiving unit, it is configured with particular sequence and receives through randomized digital broadcast signal；

Decoder, it is configured with ISN and outer code to decode received digital broadcast signal；

Control unit, its decoding activity being configured to control described decoder；

Wherein said digital broadcast signal includes each frame containing the first data field and the second data field, wherein by using the method for randomization corresponding with predefined randomization period and at least one method of carrying out in randomized method to the data being included in described second data field, having randomness to carry out digital broadcast signal described in randomization

Wherein said control unit also detects described second data field from received digital broadcast signal, and the second data detected by control are not decoded.

12. devices according to claim 11,

Wherein, for any one in units more than at least 2 frames of predefined randomization period, calendar day frame CDF, minute frame, super frame, described digital broadcast signal is carried out randomization by utilization.

13. according to the device one of claim 11 and 12 Suo Shu,

Wherein, there are described in the mutually the same data in data second data field each with at least one random period of randomness or unduplicated data are corresponding and include the random data through PRBS.

14. devices according to claim 11,

Wherein, above-mentioned control unit also performs the decoding of the digital broadcast signal of above-mentioned reception,

Wherein, above-mentioned digital broadcast signal, including

In the frame originating point information of a length of 420,595,945 symbols, at least one is with the frame head of the symbol of code, and the information frame of the frame with 3780 symbols,

Wherein, above-mentioned frame includes: the demodulating information of each information frame needs, decoded information, symbol mapping mode, LDPC code rate, intercalation model information, the relevant signal information of frame pattern information, and described frame converts from above-mentioned first data field and the second data field.