CN1490947A

CN1490947A - Transmission device with simplified digital broadcasting system and method thereof

Info

Publication number: CN1490947A
Application number: CNA031411967A
Authority: CN
Inventors: 金纪甫
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2002-10-19
Filing date: 2003-06-06
Publication date: 2004-04-21
Anticipated expiration: 2023-06-06
Also published as: CN100420170C; KR100695068B1; KR20040035293A

Abstract

A transmission device of a digital broadcasting system with simple design is provided to realize a time interleaving effect when an inter frame interleaving process is performed by gathering some FFT(Fast Fourier Transform) frames, thereby improving interleaving performance of small FFT modes. An outer encoder(210) RS-encodes an inputted TS(Transport Stream). An outer interleaver(230) re-arrays data encoded in the outer encoder(210). An inner encoder(250) convolution-encodes the re-arrayed data. An inner interleaver(270) consists of a bit interleaver(271) and a symbol interleaver(273). The bit interleaver(271) re-arrays the encoded data in bit unit. The symbol interleaver(273) re-arrays the data in symbol unit. A modulator portion(300) digitally modulates the re-arrayed data. If FFT modes of the modulator portion(300) are smaller than an 'N' mode, the symbol interleaver(273) accumulates the re-arrayed data to be 'N' mode, and re-arrays the data in symbol unit.

Description

Transmitting device and method thereof with digit broadcasting system of simplified design

Technical field

The present invention relates to a kind of transmitting device and method thereof with digit broadcasting system of simplified design, particularly, it relates to a kind of transmitting device and method thereof with digit broadcasting system of simplified design and improved interleave function.

Background technology

Compare with analog broadcasting, digital broadcasting has the advantage of the system integration and interoperability by using digital encoding system.Utilize computer and network, the requirement of assembling the core of (media convergence) as so-called medium is satisfied in digital broadcasting.In addition, the interaction feature of digital broadcasting makes big variation has taken place in unidirectional analog broadcasting.

In order to guarantee the integrated and interoperability of digital broadcasting, at first, need the introducing standard.The transmission method that the digital terrestrial television of current proposition is broadcast is the COFDM (Coded Orthogonal Frequency Division Multiplexing (COFDM)) in U.S. 8-VSB (residual sideband) and Europe.

Because digital broadcasting must send lot of data in the compressed signal source, therefore some mistakes that take place in channel influence whole system significantly.Therefore, require to reduce the mistake that in channel, takes place.In order to reduce errors, can improve through-put power to improve signal noise ratio (SNR).But, its existing problem, for example cost and the interchannel interference of exporting the raising that causes owing to the big through-put power and the height of transmitting device.In order to eliminate these problems, digit broadcasting system makes it possible to error correction and needn't improve the error correcting code of through-put power.Error correcting code can be corrected in the mistake that takes place in the channel and needn't improve through-put power, has reduced the probability that mistake takes place in receiver.

Error correcting code roughly is divided into automatic repetitive requests (ARQ) and forward error correction (FEC).According to ARQ, if there is the mistake that detects in the receiver, then receiver sends a signal that is used for the request repeat data to transmitter.Therefore, transmitter retransmits data.Because ARQ requires to make receiver to send the Return Channel of re-send request may signal to transmitter, so this method is not suitable in the digital broadcasting.Simultaneously, according to FEC, a signal sends with the additional code element that is additional to this signal, so that receiver can detect the mistake in channel and correct it with algebraic method then.

FEC roughly is divided into block code and convolution code.Block code is the Code And Decode information by piece, and it comprises Hamming code, BCH code and RS (Reed-Solomon) sign indicating number.In these sign indicating numbers, the RS sign indicating number is good on range performance, comprises effective Code And Decode algorithm, therefore has been widely used in digit broadcasting system.The RS sign indicating number is superior aspect correction burst error, because its block-by-block detects and correct mistake.

Simultaneously, for convolution code, the influence of the bit of the output bit input of being subjected to over easily and the bit of current input, and effective on the correction random error.Usually use Viterbi decoder to come decode convolutional codes.

Fig. 1 is the block diagram that the transmitting device of general digit broadcasting system schematically is shown.Referring to Fig. 1, the transmitting device of digit broadcasting system comprises scrambler 10, forward error correction (FEC) unit 20, reaches modulating unit 30.FEC unit 20 comprises external encoder 21, outer interleaver 23, internal encoder 25 and inner interleaver 27.And inner interleaver 27 comprises bit interleaver 27a and symbol interleaver 27b.Modulating unit 30 comprises mapping/OFDM modulating part 33, protection (GI) insertion parts 35, digital-to-analogue (D/A) converting member 37 and radio frequency (RF) parts 39 at interval.

Scrambler 10 will flow the data value randomization of (TS) according to the transmission of preassigned pattern input.This process is reversed execution to recover original value at receiver.

FEC unit 20 is for the possible mistake of encoding and taking place during the transfer of data to be corrected in by the data of scrambler 10 inputs.That is, external encoder 21 receives data and block-by-block coded data with error correction from scrambler 10.Generally, external encoder 21 utilizes Reed-Solomon (RS) encoder to carry out Reed-Solomon (RS) coding.Add parity check code (detected symbol) for carrying out error correction RS coding.The parity check code that is coupled with depends on transmission system.Under the situation of DVB-T method, 16 parity check codes are added on the TS of each 188 byte, and the quantity of the byte of all error correction codings is 204.

Outer interleaver 23 externally encoder 21 block-by-block coded datas interweaves, and has therefore disperseed possible burst error.Internal encoder 25 is general to be used convolution codes and the data that interleaver 23 externally interweaves is carried out convolutional encoding.The DVB-T system generally use constraint length be 7 and encoding rate be 1/2 convolution code.Again interweaved with output by inner interleaver 27 in internal encoder 25 convolution encoded data.Herein, bit interleaver 27a carries out Bit Interleave to convolution encoded data, and symbol interleaver 27b carries out symbol interleave to the data of Bit Interleave, so that carry symbol units on the OFDM subcarrier.

For in FEC unit 20 coded datas, modulating unit 30 is suitable for the digital modulation of the transmission method of broadcast system.The data map of mapping/OFDM modulating part 33 interleaver 27 outputs internally is the code element such as QPSK (Quadrature Phase Shift Keying), 16-QAM (quadrature amplitude modulation) and 64-QAM, and uses IFFT (contrary fast fourier transform) to carry out the OFDM modulation.GI insertion parts 35 is inserted a GI, is used for the ISI (inter symbol interference) that prevents at multi-path environment.The signal that 37 pairs of D/A converting members insert GI carries out the D/A conversion, and RF parts 39 amplify the signal of D/A conversion at high frequency, and it is passed through antenna transmission.

But the symbol interleaver 27b that provides in the inner interleaver 27 of the transmitting device of general digit broadcasting system uses different interleaving address according to the operator scheme of system.That is, symbol interleaver 27b sets up different interleaving address according to IFFT (contrary fast fourier transform) pattern of system.

Fig. 2 shows the symbol interleaver 27b of Fig. 1.This symbol interleaver comprises: memory b1 is used to write and read the data by bit interleaver 27a Bit Interleave; MUX b2 is used for selecting one of address generator according to mode select signal; Address generator b3 and b4 are used to produce the address that is used for symbol interleave.One of address generator is the 2K address generator; Another is the 8K address generator.MUX b2 slave controller (not shown) receiving mode is selected signal, selects one of address generator, and sends the address information that is produced by selected address generator to memory subsequently.The data that memory b1 interweaves according to the address information output symbol.

Referring to Fig. 3, the symbol interleaver 27b of 2K IFFT modular system must set up the interleaving address that has corresponding to the value of the 0-N of 2K pattern, and wherein N represents the quantity of valid data code element.The symbol interleaver 27b of 4K IFFT modular system must set up the interleaving address that has corresponding to the value of the 0-2N of 4K pattern.And the symbol interleaver 27b of 8K IFFT modular system must set up the interleaving address that has corresponding to the value of the 0-4N of 8K pattern.For example, the digit broadcasting system of DVB-T method only uses 2K IFFT pattern and 8K IFFT pattern, and they require different interleaving address generators.That is,, require different interleaving address generators for two types pattern.Therefore, digit broadcasting system needs different designs according to employed IFFT pattern.This also makes the design complexity of receiving system.Particularly, set up under the situation of interleaving address by using look-up table in symbol interleaver, symbol interleaver must comprise the different look-up table according to the IFFT pattern.Therefore, the complexity of the design of digit broadcasting system becomes more serious.

And under the situation such as the smallest number IFFT pattern of 2K and 4K pattern, the quantity of effective code element is little, therefore interweave not as the situation of 8K pattern effective like that.Therefore, may carry out interweaving of 2K and 4K modular system like that well not as the 8K pattern.

Summary of the invention

Development the objective of the invention is in order to solve the aforementioned problems in the prior.Therefore, an object of the present invention is to provide the transmitting device and the method thereof of the digit broadcasting system of a kind of design with simplification and improved interleave function.

Realize above-mentioned purpose by the transmitting device that a kind of digit broadcasting system is provided, this transmitting device comprises: Reed-Solomon (RS) encoder is used for the transmission stream (TS) of input is carried out the RS coding; Outer interleaver, data by the RS encoder encodes are used to interweave; Convolution coder is used for the data that interweaved by outer interleaver are carried out convolutional encoding; Inner interleaver has and is used for the bit interleaver that carried out Bit Interleave by the convolution coder coded data and is used for the data that interweaved by bit interleaver are carried out the symbol interleaver of symbol interleave; Modulating unit is used for the data that interweaved by inner interleaver are carried out digital modulation.At this, when contrary fast fourier transform (IFFT) pattern of system the time less than the N pattern of symbol interleaver---wherein N is a natural number, the data accumulation that symbol interleaver will be interweaved by bit interleaver is the unit interleaving data with the code element to the degree corresponding to the N pattern then.And the IFFT pattern is any in 2K pattern, 4K pattern and the 8K pattern, and the N pattern is the 8K pattern.

Preferably, symbol interleaver comprises a memory and an address generator, is used for utilizing the max model interleaving data of multiple IFFT pattern.

Preferably, the transmitting device of digit broadcasting system also comprises: memory is used for when the IFFT pattern of system less than the N pattern of symbol interleaver the time---and wherein N is a natural number, and the data that bit interleaver interweaves are accumulated; Controller is used for detecting the data of accumulating at memory, and the data that the control symbol interleaver interweaves and accumulated when the data of accumulation have identical size in the N pattern.

Simultaneously, a kind of transmission method according to digit broadcasting system of the present invention comprises the following steps: the transmission stream (TS) of input is carried out the RS coding; Coded data in the RS coding step interweaves; The data that interweave in RS interweaves step are carried out convolutional encoding; Coded data in the convolutional encoding step is carried out Bit Interleave; The data that interweave in the Bit Interleave step are carried out symbol interleave; With the data that interweave in the symbol interleave step are carried out digital modulation, wherein, when contrary fast fourier transform (IFFT) pattern of modulation step the time less than the N pattern of symbol interleave step---wherein N is a natural number, and the symbol interleave step comprises step: the data accumulation that will be interweaved by the Bit Interleave step is to the degree corresponding to the N pattern.

Description of drawings

By reference description of drawings the preferred embodiments of the present invention, above-mentioned purpose of the present invention and characteristics will become apparent, wherein:

Fig. 1 is the block diagram that the transmitting device of general digit broadcasting system schematically is shown;

Fig. 2 shows the symbol interleaver 27b of Fig. 1;

Fig. 3 is the view that is used to illustrate according to the operation of the symbol interleaver of the IFFT pattern of Fig. 2;

Fig. 4 shows the symbol interleaver according to the preferred embodiment of the present invention; With

Fig. 5 is the view that is used to illustrate according to the operation of the symbol interleaver of the IFFT pattern of Fig. 4.

Embodiment

Below, be described in more detail the present invention with reference to accompanying drawing.

Fig. 4 shows the symbol interleaver according to the preferred embodiments of the present invention.This symbol interleaver comprises: memory 1, the data that are used to write and read the Bit Interleave of being exported by bit interleaver; Address generator 2, it produces the address that is used for symbol interleave.Memory 1 is according to the data of the address information that is produced by address generator 2 to modulating unit output Bit Interleave.Modulating unit is ofdm signal according to the pattern information that receives from the system controller (not shown) with the data-modulated of symbol interleave.When transmitter of the present invention had the N-IFFT pattern, the size of symbol interleaver parts was confirmed as maximum IFFT pattern.For example, as shown in Figure 5, if transmitter has 2K, 4K, 8K pattern, then the size of symbol interleaver parts is confirmed as the 8K pattern, so address generator 2 is 8K address generators.It produces M address, is the quantity of 8K mode data carrier wave at this M.When transmitter will send with the 2K pattern, modulating unit is unit with M/4 with the data-modulated of symbol interleave was ofdm signal.In an identical manner, when transmitter will send with the 4K pattern, modulating unit is unit with M/2 with the data-modulated of symbol interleave was ofdm signal.In the 8K pattern, modulating unit is modulated the data of all M symbol interleave.

Because do not require according to IFFT pattern design system and only require the interleaving address generator of 8K pattern differently according to the transmitting device of digit broadcasting system of the present invention, design that therefore can simplified system.

And, according to the transmitting device of digit broadcasting system of the present invention when it carries out and have time-interleaved effect when interframe interweaves by collecting several IFFT frames.Therefore, for IFFT pattern, can improve felt properties with smallest number subcarrier symbol such as 2K pattern and 4K pattern.

Above-mentioned preferred embodiment and advantage only are schematically, should not be understood that limitation of the present invention.Can easily be applied to the device of other types in this content of setting forth.Specification of the present invention be intended to illustrate and be not used in the restriction claim scope.It is many for a person skilled in the art that to substitute, revise and change be obvious.In the claims, device adds that the statement of function is intended to cover the structure of the described function of execution described here, not only comprises equivalent structures, and comprises equivalent configurations.

Claims

1. the transmitting device of a digit broadcasting system, described transmitting device comprises:

External encoder is used for the transmission stream of input is encoded;

Outer interleaver, data by outer encoder are used to interweave;

Internal encoder is used for the data that interweaved by outer interleaver are encoded;

Inner interleaver has and is used for the bit interleaver that carried out Bit Interleave by the internal encoder coded data and is used for the data that interweaved by bit interleaver are carried out the symbol interleaver of symbol interleave;

Modulating unit is used for the data that interweaved by inner interleaver are carried out digital modulation,

Wherein, described symbol interleaver uses the maximum IFFT pattern in a plurality of IFFT patterns to interweave by the data of Bit Interleave.

2. according to the transmitting device of claim 1, wherein the IFFT pattern is any pattern in 2K pattern, 4K pattern and the 8K pattern, and max model is the 8K pattern.

3. according to the transmitting device of claim 1, wherein said external encoder is a Reed-Solomon encoder.

4. according to the transmitting device of claim 1, wherein internal encoder is a convolution coder.

5. according to the transmitting device of claim 1, wherein said modulating unit is the data that the unit modulated symbol interweaves with determined IFFT pattern.

6. according to the transmitting device of claim 1, described symbol interleaver comprises memory and address generator, is used for utilizing the maximum IFFT pattern in a plurality of IFFT patterns to come interleaving data.

7. the transmission method of a digit broadcasting system comprises the following steps:

Transmission stream to input carries out external encode;

Coded data in the coding step interweaves externally;

The data that interweave in the step that interweaves are carried out in-line coding;

Coded data in the in-line coding step is carried out Bit Interleave;

The data that interweave in the Bit Interleave step are carried out symbol interleave;

The data that interweave in the symbol interleave step are carried out digital modulation,

Wherein, in described symbol interleave step, use the maximum IFFT pattern in a plurality of IFFT patterns to interweave by the data of Bit Interleave.

8. according to the transmission method of claim 7, wherein the IFFT pattern is any pattern in 2K pattern, 4K pattern and the 8K pattern, and max model is the 8K pattern.

9. according to the transmission method of claim 7, wherein externally carry out the Reed-Solomon coding in the coding step.

10. according to the transmission method of claim 7, wherein in the in-line coding step, carry out convolutional encoding.

11., in the digital modulation step, be the data that the unit modulated symbol interweaves wherein with determined IFFT pattern according to the transmission method of claim 7.