CN101383807A - Digital television ground broadcast transmitter modulation method based on embedded training sequence - Google Patents
Digital television ground broadcast transmitter modulation method based on embedded training sequence Download PDFInfo
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- CN101383807A CN101383807A CNA2008102282844A CN200810228284A CN101383807A CN 101383807 A CN101383807 A CN 101383807A CN A2008102282844 A CNA2008102282844 A CN A2008102282844A CN 200810228284 A CN200810228284 A CN 200810228284A CN 101383807 A CN101383807 A CN 101383807A
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Abstract
The invention discloses a modulation method of a digital television terrestrial broadcast transmitter based on an embedded training sequence. The modulation method comprises the following steps: (1) an input bit stream forms an FFT data block on a frequency domain; (2) the FFT data block is converted into a time domain discrete data sample block by IFFT; (3) the training sequence is used as a real part sequence and a service index sequence is used as an imaginary-part sequence so as to form a discrete sample block of a complex training sequence; (4) the complex training sequence is continuously repeated for 4 times so as to form a time domain embedded training sequence discrete sample block; (5) the time domain discrete data sample block and the time domain embedded training sequence discrete sample block are superposed to form a time domain embedded training sequence data block; (6) a cyclic prefix is inserted into the time domain embedded training sequence data block as a guard interval so as to form a signal frame; (7) a square root raised consine roll-off filter is used to carry out pulse shaping to the signal frame; and (8) a baseband signal is carried out up-variation frequency to a carrier wave. The method has the advantages of short synchronizing time, channel fading resistance, controllable multi-service, and the like.
Description
Technical field
The invention belongs to wireless communication field, relate more specifically to a kind of based on the digital television ground broadcast transmitter modulation method that embeds training sequence.
Background technology
At present, ground TV broadcast develops to the digitlization direction gradually from simulation.Digital television ground broadcast transmission system, as the important component part of Digital Television Terrestrial Broadcasting, its development of technologies, closely bound up with people's quality of life, and therefore be subjected to people's extensive concern especially.Digital Television Terrestrial Broadcasting correlation technique and related industry thereof are that development is very fast in the Communications And Computer field, the industry of good market prospect.On the Digital Television Terrestrial Broadcasting correlation technique, the emphasis of various countries' concern at present is that the Digital Television Terrestrial Broadcasting how to pass under the environment for complex wave provides the implementation of reliable high-speed mobile cheaply.The digital television ground broadcast transmitter modulation technique is the key technology of digital tv ground broadcasting, for whole system performance decisive role, is the object of everybody primary study.
Because the develop rapidly of Digital Signal Processing and integrated circuit technique, the system of OFDM (OFDM) technology realizes becoming more and more easier.Because of OFDM multi-carrier transmission technology has simple in structure, the availability of frequency spectrum high plurality of advantages such as becomes and extremely everybody concern and obtain deep research and the extensive use in numerous areas such as Xdsl, wide-band mobile communication, wideband wireless local area network, Digital Television Terrestrial Broadcasting in the time of can resisting frequency selectivity and channel.
In the practical communication environment, the Digital Television Terrestrial Broadcasting communication system performance is subjected to the influence of factors such as lock in time, clock jitter, channel fading, channel disturbance.Transmitter modulation method is the key technology that realizes the reliable digit television terrestrial broadcasting.
Utilizing digital television ground broadcast transmission system that may command multi-services such as free television broadcasting, paid television broadcasting, security information transmission, multimedia value-added service are provided is embodiments that digital television ground broadcast transmission system of new generation satisfies social needs.
Just be based on above background, the present invention is directed to the practical communication environment and propose a kind of digital television ground broadcast transmitter modulation method, can satisfy the needs of High Data Rate may command multi-service Digital Television Terrestrial Broadcasting transmission based on the embedding training sequence.
Desire is done more deep understanding to the patent background can be with reference to following documents and materials:
R.V.Nee，R.Prasad.“OFDM?for?wireless?multimedia?communications”.Boston：Artech?House，2000.
M.Speth，S.Fechtel，G.Fock，and?H.Meyr.“Optimum?receiver?design?forOFDM-based?broadband?transmission-Part?II：A?case?study，”IEEE?Trans.Commun.，vol.49，pp.571-578，April?2001.
Y.Wu，S.Hirakawa，U.H.Reimers，and?J.Whitaker.“Overview?of?digitaltelevision?development，”Proceedings?of?the?IEEE，Special?Issue?on?GlobalDigital?Television：Technology?and?Emerging?Services，pp.8-21，Jan.2006.
M.S.Richer，G.Reitmeier，T.Gurley，G.A.Jones，J.Whitaker，and?R.Rast.“The?ATSC?digital?television?system，”Proceedings?of?the?IEEE，Special?Issue?on?Global?Digital?Television：Technology?and?EmergingServices，pp.37-43，Jan.2006.
U.Ladebusch?and?C.A.Liss.“Terrestrial?DVB(DVB-T)：A?broadcasttechnology?for?stationary?portable?and?mobi?le?use，”Proceedings?of?theIEEE，Special?Issue?on?Global?Digital?Television：Technology?and?EmergingServices，pp.183-194，Jan.2006.
M.Takada?and?M.Saito.“Transmission?systems?for?ISDB-T，”Proceedingsof?the?IEEE，Special?Issue?on?Global?Digital?Television：Technology?andEmerging?Services，pp.251-256，Jan.2006.
Summary of the invention
The present invention is directed to High Data Rate may command multi-service Digital Television Terrestrial Broadcasting problem, proposed a kind of based on the digital television ground broadcast transmitter modulation method that embeds training sequence.
What the present invention proposed is a kind of based on the digital television ground broadcast transmitter modulation method that embeds training sequence, it is characterized in that it comprises the following steps:
1) digital television ground broadcast transmitter forms FFT data block (length of FFT data block (symbol numbers) is K) with the input data bit flow of oneself on frequency domain;
2) digital television ground broadcast transmitter adopts IFFT (fast discrete Fourier inverse transformation) the FFT data block to be transformed to the discrete data sample block of time domain;
3) digital television ground broadcast transmitter as the real part sequence of sequence of plural training, with the imaginary part sequence of operational indicator sequence as sequence of plural training, constitutes the discrete sample block (length of the discrete sample block of training sequence, operational indicator sequence, sequence of plural training all is X) of sequence of plural training with training sequence on time domain;
4) digital television ground broadcast transmitter will repeat to form for 4 times time domain continuously in the discrete sample block of the sequence of plural training that constitutes on the time domain and embed training sequence discrete sample block (length that time domain embeds training sequence discrete sample block is K, K=4 * X) on time domain;
5) digital television ground broadcast transmitter embeds training sequence discrete sample block with the discrete data sample block of time domain, time domain and directly superposes and form time domain and embed the training sequence data piece, as frame;
6) digital television ground broadcast transmitter inserts time domain with Cyclic Prefix (length of Cyclic Prefix is C) as protection interval (frame head) and embeds training sequence data piece (frame), to form signal frame;
7) digital television ground broadcast transmitter adopts square root raised cosine filter that the signal pulse of signal frame is shaped;
8) digital television ground broadcast transmitter with the baseband signal up-conversion to carrier wave.
The digital television ground broadcast transmitter modulation method based on the embedding training sequence according to above-mentioned is characterized in that: have periodic time domain in the signal frame of digital television ground broadcast transmitter and embed training sequence discrete sample block; The length X of the training sequence of digital television ground broadcast transmitter is in 512,1024,2048, the length K of corresponding FFT data block (sub-carrier number) is respectively 2048,4096,8192, the frequency interval of corresponding subcarrier is respectively 4KHz, 2KHz, 1KHz, and corresponding circulating prefix-length C is respectively 1/4,1/8,1/16 of FFT data block length K size; The training sequence of digital television ground broadcast transmitter, operational indicator sequence are formed by a series of 1 or-1, have pseudo-random characteristics; The training sequence of digital television ground broadcast transmitter, operational indicator sequence have orthogonality each other; The different operational indicator sequence of each of digital television ground broadcast transmitter is comprising and unique each system parameters and business model information of expressing digital television ground broadcast transmitter.
Characteristics of the present invention:
The present invention is the modulation scheme that a kind of time-domain and frequency-domain mixes.Have periodic time domain in the signal frame of digital television ground broadcast transmitter and embed training sequence discrete sample block, the training sequence of digital television ground broadcast transmitter, the operational indicator sequence has pseudo-random characteristics, the training sequence of digital television ground broadcast transmitter, the operational indicator sequence has orthogonality each other, the time domain embedding training sequence data piece of digital television ground broadcast transmitter is the discrete data sample block by time domain, time domain embeds training sequence discrete sample block and directly superposes and form, and these have guaranteed that digital television ground broadcast transmitter can realize frame synchronization fast and accurately, Frequency Synchronization, time synchronized, channel transfer characteristic is estimated, and phase noise and channel transfer characteristic reliably followed the tracks of.Cyclic Prefix is inserted time domain at interval as protection embed the training sequence data piece, can reduce the interference effect between the adjacent signals frame to form signal frame.The different operational indicator sequence of each of digital television ground broadcast transmitter is comprising and unique each system parameters and business model information of expressing digital television ground broadcast transmitter, digital television ground broadcast transmission system can satisfy social needs so that can provide may command multi-services such as free television broadcasting, paid television broadcasting, security information transmission, multimedia value-added service.Modulator approach of the present invention have lock in time short, clock jitter is little, anti-channel fading, anti-channel disturbance, can provide plurality of advantages such as High Data Rate may command multi-service Digital Television Terrestrial Broadcasting transmission.
Description of drawings
Fig. 1 is the embodiment schematic diagram according to certain transmitter based on the digital television ground broadcast transmitter modulation method that embeds training sequence of the present invention.
Fig. 2 is the embodiment schematic diagram that forms signal frame based on certain transmitter of the digital television ground broadcast transmitter modulation method that embeds training sequence according to of the present invention.
Embodiment
Below in conjunction with accompanying drawing specific embodiments of the invention are described in detail.
The embodiment based on certain transmitter of the digital television ground broadcast transmitter modulation method that embeds training sequence according to the present invention proposes as shown in Figure 1, follows these steps to carry out:
1) this certain digital television ground broadcast transmitter forms the FFT data block with oneself input data bit flow (length of FFT data block (symbol numbers) is K on frequency domain; When X got 512, the length K of corresponding FFT data block (sub-carrier number) got 2048, and the frequency interval of corresponding subcarrier is got 4KHz; When X got 1024, the length K of corresponding FFT data block (sub-carrier number) got 4096, and the frequency interval of corresponding subcarrier is got 2KHz; When X got 2048, the length K of corresponding FFT data block (sub-carrier number) got 8192, and the frequency interval of corresponding subcarrier is got 1KHz);
2) this certain digital television ground broadcast transmitter adopts IFFT (fast discrete Fourier inverse transformation) the FFT data block to be transformed to the discrete data sample block of time domain;
3) this certain digital television ground broadcast transmitter with training sequence as the real part sequence of sequence of plural training, with the imaginary part sequence of operational indicator sequence as sequence of plural training, on time domain, constitute the discrete sample block (length of the discrete sample block of training sequence, operational indicator sequence, sequence of plural training all is X, and X gets in 512,1024,2048) of sequence of plural training;
4) this certain digital television ground broadcast transmitter will repeat to form for 4 times time domain continuously in the discrete sample block of the sequence of plural training that constitutes on the time domain and embed training sequence discrete sample block (length that time domain embeds training sequence discrete sample block is K, K=4 * X) on time domain;
5) this certain digital television ground broadcast transmitter embeds training sequence discrete sample block with the discrete data sample block of time domain, time domain and directly superposes and form time domain and embed the training sequence data piece, as frame;
6) (length of Cyclic Prefix is C to this certain digital television ground broadcast transmitter with Cyclic Prefix; When X got 512, corresponding C got 1/4 of FFT data block length K size; When X got 1024, corresponding C got 1/8 of FFT data block length K size; When X gets 2048, corresponding C get FFT data block length K size 1/16) as protection at interval (frame head) insert time domain and embed training sequence data piece (frame), to form signal frame;
7) this certain digital television ground broadcast transmitter adopts square root raised cosine filter that the signal pulse of signal frame is shaped;
8) this certain digital television ground broadcast transmitter with the baseband signal up-conversion to carrier wave.
Form the embodiment of signal frame according to of the present invention based on certain transmitter of the digital television ground broadcast transmitter modulation method that embeds training sequence, as shown in Figure 2, specifically implement as follows:
This certain digital television ground broadcast transmitter forms the FFT data block with the input data bit flow of oneself on frequency domain, through IFFT it is transformed to the discrete data sample block of time domain again.
The FFT data block is made up of subcarrier.The length of FFT data block (symbol numbers) is K; When X got 512, the length K of corresponding FFT data block (sub-carrier number) got 2048, and the frequency interval of corresponding subcarrier is got 4KHz; When X got 1024, the length K of corresponding FFT data block (sub-carrier number) got 4096, and the frequency interval of corresponding subcarrier is got 2XHz; When X got 2048, the length K of corresponding FFT data block (sub-carrier number) got 8192, and the frequency interval of corresponding subcarrier is got 1KHz.
This certain digital television ground broadcast transmitter with training sequence as the real part sequence of sequence of plural training, with the imaginary part sequence of operational indicator sequence as sequence of plural training, on time domain, constitute the discrete sample block of sequence of plural training, on time domain, it is repeated 4 times continuously again and form time domain embedding training sequence discrete sample block.
The length of the discrete sample block of training sequence, operational indicator sequence, sequence of plural training all is X, and X gets in 512,1024,2048, and the length that time domain embeds training sequence discrete sample block is K, K=4 * X.
Training sequence, operational indicator sequence as digital television ground broadcast transmitter are formed by a series of 1 or-1, have pseudo-random characteristics, and training sequence, operational indicator sequence have orthogonality each other.The training sequence that satisfies above-mentioned feature can be by realizing as one group of displacement m sequence of a kind of specific type of pseudo-random number sequence with as the walsh sequence of orthogonal sequence, Hadamard sequences or by the orthogonal sequence that other modes produce.
Each different operational indicator sequence is comprising and unique each system parameters and business model information of expressing digital television ground broadcast transmitter.
This certain digital television ground broadcast transmitter embeds training sequence discrete sample block with the discrete data sample block of time domain, time domain and directly superposes and form time domain and embed the training sequence data piece, as frame; In time domain embedding training sequence data piece, insert Cyclic Prefix at interval, form signal frame as protection.
Length as protection Cyclic Prefix at interval is C; When X got 512, corresponding C got 1/4 of FFT data block length K size; When X got 1024, corresponding C got 1/8 of FFT data block length K size; When X got 2048, corresponding C got 1/16 of FFT data block length K size.
This certain digital television ground broadcast transmitter adopts square root raised cosine filter that the signal of signal frame is carried out pulse shaping.When X got 512, the rolloff-factor that corresponding signal to signal frame carries out the square root raised cosine filter of pulse shaping got 0.1; When X got 1024, the rolloff-factor that corresponding signal to signal frame carries out the square root raised cosine filter of pulse shaping got 0.05; When X got 2048, the rolloff-factor that corresponding signal to signal frame carries out the square root raised cosine filter of pulse shaping got 0.025.
In conjunction with the accompanying drawings specific embodiments of the invention are had been described in detail above, but the present invention is not limited to the foregoing description, under the spirit and scope situation of the claim that does not break away from the application, those skilled in the art can make various modifications or remodeling.
Claims (8)
1, a kind of based on the digital television ground broadcast transmitter modulation method that embeds training sequence, it is characterized in that it comprises the following steps:
1) digital television ground broadcast transmitter forms FFT data block (length of FFT data block (symbol numbers) is K) with the input data bit flow of oneself on frequency domain;
2) digital television ground broadcast transmitter adopts IFFT (fast discrete Fourier inverse transformation) the FFT data block to be transformed to the discrete data sample block of time domain;
3) digital television ground broadcast transmitter as the real part sequence of sequence of plural training, with the imaginary part sequence of operational indicator sequence as sequence of plural training, constitutes the discrete sample block (length of the discrete sample block of training sequence, operational indicator sequence, sequence of plural training all is X) of sequence of plural training with training sequence on time domain;
4) digital television ground broadcast transmitter will repeat to form for 4 times time domain continuously in the discrete sample block of the sequence of plural training that constitutes on the time domain and embed training sequence discrete sample block (length that time domain embeds training sequence discrete sample block is K, K=4 * X) on time domain;
5) digital television ground broadcast transmitter embeds training sequence discrete sample block with the discrete data sample block of time domain, time domain and directly superposes and form time domain and embed the training sequence data piece, as frame;
6) digital television ground broadcast transmitter inserts time domain with Cyclic Prefix (length of Cyclic Prefix is C) as protection interval (frame head) and embeds training sequence data piece (frame), to form signal frame;
7) digital television ground broadcast transmitter adopts square root raised cosine filter that the signal pulse of signal frame is shaped;
8) digital television ground broadcast transmitter with the baseband signal up-conversion to carrier wave.
2, by the digital television ground broadcast transmitter modulation method based on the embedding training sequence of claim 1, it is characterized in that: the length X of the discrete sample block of the training sequence of described digital television ground broadcast transmitter, operational indicator sequence, sequence of plural training is got in 512,1024,2048.
3, by the digital television ground broadcast transmitter modulation method based on the embedding training sequence of claim 2, it is characterized in that: described training sequence, operational indicator sequence have pseudo-random characteristics.
4, by the digital television ground broadcast transmitter modulation method based on the embedding training sequence of claim 2, it is characterized in that: described training sequence, operational indicator sequence have orthogonality each other.
5, by the digital television ground broadcast transmitter modulation method based on the embedding training sequence of claim 1, it is characterized in that: described FFT data block is made up of subcarrier; When X got 512, sub-carrier number K got 2048; When X got 1024, sub-carrier number K got 4096; When X got 2048, sub-carrier number K got 8192.
6, by the digital television ground broadcast transmitter modulation method based on the embedding training sequence of claim 1, it is characterized in that: described FFT data block is made up of subcarrier, and when X got 512, the frequency interval of subcarrier was got 4KHz; When X got 1024, the frequency interval of subcarrier was got 2KHz; When X got 2048, the frequency interval of subcarrier was got 1KHz.
7, by the digital television ground broadcast transmitter modulation method based on the embedding training sequence of claim 1, it is characterized in that: described signal frame is inserted into time domain embedding training sequence data piece by Cyclic Prefix at interval as protection and forms.
8, by the digital television ground broadcast transmitter modulation method based on the embedding training sequence of claim 1, it is characterized in that: the length of described Cyclic Prefix is C; When X got 512, C got 1/4 of K size; When X got 1024, C got 1/8 of K size; When X got 2048, C got 1/16 of K size.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101778082A (en) * | 2010-03-03 | 2010-07-14 | 宁波大学 | Wireless multi-media broadcast signal transmission method |
| WO2010102492A1 (en) * | 2009-03-12 | 2010-09-16 | 中兴通讯股份有限公司 | Method and processing apparatus for implementing ifft by using fft |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010102492A1 (en) * | 2009-03-12 | 2010-09-16 | 中兴通讯股份有限公司 | Method and processing apparatus for implementing ifft by using fft |
| CN101778082A (en) * | 2010-03-03 | 2010-07-14 | 宁波大学 | Wireless multi-media broadcast signal transmission method |
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Open date: 20090311 |