CN102263750B - Method for transmitting mobile digital broadcast signals of single-frequency network - Google Patents
Method for transmitting mobile digital broadcast signals of single-frequency network Download PDFInfo
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Abstract
The invention discloses a method for transmitting mobile digital broadcast signals of a single-frequency network, and relates to a time domain/frequency domain/air space mixed framing modulating scheme. The method for transmitting mobile digital broadcast signals of the single-frequency network has the advantages of low peak-to-average power ratio, short synchronization time, resistance to channel fading, controllable multiple services and the like.
Description
Technical field
The invention belongs to moving communicating field, relate more specifically to a kind of method for transmitting mobile digital broadcast signals of single-frequency network.
Background technology
The digital television mobile digital broadcasting transmission system, as the important component part of digital television mobile digital broadcasting, the development of its correlation technique, closely bound up with people's quality of life, and therefore be subject to people's extensive concern especially.Digital television mobile digital 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 digital television mobile digital broadcasting correlation technique, various countries' outline is at present, and the digital television mobile digital broadcasting how to pass under the environment for complex wave provides the cheaply implementation of reliable high-speed mobile.Mobile digital broadcast signal transmitter transmission technology is the key technology of digital television mobile digit broadcasting system, plays conclusive effect for the whole system performance, 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 the OFDM Multicarrier Transmission Technology has simple in structure, the availability of frequency spectrum is high, the plurality of advantages such as becomes in the time of can resisting frequency selectivity and channel and extremely everybody concern and obtain deep research and the extensive use in the numerous areas such as Xdsl, wide-band mobile communication, broadband mobile local area network (LAN), digital television mobile digital broadcasting.
The peak-to-average power ratio that ofdm signal is higher (PAPR) has very high requirement to the range of linearity of amplifier and digital to analog converter, if the system linearity scope can not satisfy the variation of signal, then can cause signal distortion, signal spectrum is changed, thereby cause the orthogonality between the subchannel to be destroyed, produce the phase mutual interference, make system performance degradation.Therefore, the solution that must consider how to reduce the probability of occurrence of large peak power signal in the ofdm signal and reduce the nonlinear distortion impact.
The networking model of employing single frequency network (that is, the same time of several transmitting stations is launched same signal to realize the reliable covering to certain coverage in same frequency) can improve the availability of frequency spectrum of digital television mobile digital broadcasting transmission system greatly.In actual single frequency network communication environment, digital television mobile digital broadcast communications system performance is subject to the impact of the factors such as lock in time, clock jitter, channel fading, channel disturbance.Single frequency network mobile digital broadcast signal transmitter transmission method is the key technology that realizes reliable digit TV monochromatic network mobile digital broadcast.
Utilizing digital television single-frequency network mobile digital broadcast transmission system to provide free television broadcasting, paid television broadcasting, Secret Information Transmission, multimedia value-added service etc. can control multi-service is the embodiment that new-generation digital TV mobile digital broadcast transmission system satisfies social needs.
Just be based on above background, the present invention is directed to the practical communication environment and propose a kind of method for transmitting mobile digital broadcast signals of single-frequency network, can satisfy the needs that High Data Rate can be controlled the transmission of multi-service digital television single-frequency network mobile digital broadcast.
Wish 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.
Y.Wu，S.Hirakawa，U.H.Reimers，and?J.Whitaker.“Overview?of?digital?television?development，”Proceedings?of?the?IEEE，Special?Issue?on?Global?Digital?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?Emerging?Services，pp.37-43，Jan.2006.
U.Ladebusch?and?C.A.Liss.“Terrestrial?DVB(DVB-T)：A?broadcast?technology?for?stationary?portable?and?mobile?use，”Proceedings?of?the?IEEE，Special?Issue?on?Global?Digital?Television：Technology?and?Emerging?Services，pp.183-194，Jan.2006.
M.Takada?and?M.Saito.“Transmission?systems?for?ISDB-T，”Proceedings?of?the?IEEE，Special?Issueon?Global?Digital?Television：Technology?and?Emerging?Services，pp.251-256，Jan.2006.
Summary of the invention
The present invention is directed to High Data Rate and can control multi-service digital television single-frequency network mobile digital broadcast problem, proposed a kind of method for transmitting mobile digital broadcast signals of single-frequency network.
A kind of method for transmitting mobile digital broadcast signals of single-frequency network that the present invention proposes is characterized in that it comprises the following steps:
1) the centre data manager of single frequency network converts the multi-medium data media data processor of flowing through to bit stream, and the scrambler sequence of utilizing feedback shift register to produce is carried out scrambling and processed to form the input data bit flow;
2) the network data management device of single frequency network will be inputted flow through code element modulation of data bit and be rotated in code element and form the FFT data block on the frequency domain, and FFT represents the fast discrete Fourier conversion, and the length of FFT data block is K;
3) to adopt code check be that 1 space-frequency coding device will be modulated in the FFT data block that frequency domain forms each mobile digital broadcast signal transmitter branch road in the single frequency network and form and emptyly frequently modulate the FFT data block to the network data management device of single frequency network, and the time synchronized of adjusting each mobile digital broadcast signal transmitter branch road is all frequently modulated the FFT data block to sky at one time and processed to guarantee all transmitters in the network;
4) each mobile digital broadcast signal transmitter in the single frequency network adopts IFFT that sky is modulated the FFT data block frequently and is transformed to the empty time domain discrete data sample block D that frequently modulates
Total, IFFT represents the fast discrete Fourier inverse transformation;
5) each mobile digital broadcast signal transmitter in the single frequency network is frequently modulated sky in order time domain discrete data sample block and is divided equally into two, the empty time domain discrete data sample sub-block D that frequently modulates
1Frequently modulate time domain discrete data sample sub-block D with sky
2, D
Total=[D
1, D
2];
6) each mobile digital broadcast signal transmitter in the single frequency network is modulated time domain discrete data sample sub-block D by the peak-to-average power ratio adjustment unit frequently to sky
1, the empty time domain discrete data sample sub-block D that frequently modulates
2Carry out that signal adds, subtracts, conjugate operation is processed and the synthetic new empty time domain discrete data sample block D that frequently modulates again
New, the new empty time domain discrete data sample block D that frequently modulates
NewAdopt following generate pattern to obtain, generate pattern 1 is D
New=[D
1, D
2], generate pattern 2 is
Generate pattern 3 is
Generate pattern 4 is
Generate pattern 5 is
Generate pattern 6 is
Generate pattern 7 is D
New=[D
* 1, D
2], generate pattern 8 is
Generate pattern 9 is
Generate pattern 10 is
Generate pattern 11 is
Generate pattern 12 is
Relatively 12 kinds of synthetic empty frequencies of generate pattern are modulated time domain discrete data sample block D
New, choose the empty frequency of peak-to-average power ratio that falls that wherein has minimum peak-to-average power ratio and modulate time domain discrete data sample block
And the empty time domain discrete data sample block of frequently modulating of peak-to-average power ratio will be fallen
The corresponding generate pattern information that adopts send to operational indicator sequence setting unit, wherein, D
* 1Expression is modulated time domain discrete data sample sub-block D frequently to sky
1Each empty modulate that time domain discrete data sample carries out that conjugate operation is processed frequently and the empty time domain discrete data sample sub-block of frequently modulating that obtains;
7) each mobile digital broadcast signal transmitter in the single frequency network with training sequence as the real part sequence of sequence of plural training, operational indicator sequence that operational indicator sequence setting unit is the set imaginary part sequence as sequence of plural training, consist of the discrete sample block of sequence of plural training in time domain, the length of the discrete sample block of training sequence, operational indicator sequence, sequence of plural training all is X, and the operational indicator sequence is comprising and unique each system parameters and business model information of expressing each mobile digital broadcast signal transmitter in the single frequency network;
8) discrete sample block of the sequence of plural training that will consist of in time domain of each mobile digital broadcast signal transmitter in the single frequency network repeats continuously to form time domains 4 times and embeds training sequence discrete sample block on time domain, time domain embeds the length of training sequence discrete sample block and falls the empty length numerically equal of modulating time domain discrete data sample block frequently of peak-to-average power ratio, i.e. K=4 * X;
9) each mobile digital broadcast signal transmitter in the single frequency network will fall the empty time domain discrete data sample block, time domain of frequently modulating of peak-to-average power ratio and embed training sequence discrete sample block and directly superpose and form time domain and embed training sequence and fall that peak-to-average power ratio is empty frequently modulates time domain discrete data sample block, as frame;
10) each mobile digital broadcast signal transmitter in the single frequency network is that frame head inserts time domain and embeds training sequence and fall peak-to-average power ratio empty frequently to modulate time domain discrete data sample block be frame with Cyclic Prefix as the protection interval, to form signal frame, the length of Cyclic Prefix is C;
11) each mobile digital broadcast signal transmitter in the single frequency network adopts square root raised cosine filter that the signal pulse of signal frame is shaped;
12) each mobile digital broadcast signal transmitter in the single frequency network forms emission of radio frequency signals to the on-air radio channel with the baseband signal up-conversion to carrier wave;
13) the mobile digital broadcast signal receiver in the single frequency network detect to receive radiofrequency signal that each mobile digital broadcast signal transmitter in the single frequency network sends and its down-conversion is formed baseband signal, utilizes the Cyclic Prefix characteristic of signal frame and the architectural characteristic of signal frame to carry out the baseband signal reception ﹠ disposal.
Method for transmitting mobile digital broadcast signals of single-frequency network according to above-mentioned is characterized in that: each mobile digital broadcast signal transmitter in the single frequency network fall that peak-to-average power ratio is empty modulates that time domain discrete data sample block modulates frequently by sky that the signal that the time domain discrete data sample sub-block undertaken by specific 12 kinds of generate patterns adds, subtracts, conjugate operation is processed frequently and again synthetic; Have periodic time domain in the signal frame of each mobile digital broadcast signal transmitter in the single frequency network and embed training sequence discrete sample block; The length X of the training sequence of each mobile digital broadcast signal transmitter in the single frequency network is in 512,1024,2048, corresponding empty length K of modulating the FFT data block frequently is respectively 2048,4096,8192, the frequency interval of corresponding subcarrier is respectively 4KHz, 2KHz, 1KHz, and corresponding circulating prefix-length C is respectively empty 1/4,1/8,1/16 of the FFT data block length K size of frequently modulating; The training sequence of each mobile digital broadcast signal transmitter in the single frequency network, operational indicator sequence form by a series of 1 or-1, have pseudo-random characteristics; Training sequence, the operational indicator sequence of each mobile digital broadcast signal transmitter in the single frequency network have orthogonality each other; Each different operational indicator sequence of each mobile digital broadcast signal transmitter in the single frequency network is comprising and unique each system parameters and business model information of expressing each mobile digital broadcast signal transmitter in the single frequency network; Code element is modulated to a kind of among QPSK, 16QAM, 64QAM and the 256QAM, and the symbol constellations figure mapping mode of code element modulation adopts the Gray code mapping; The code element rotation realizes by symbol constellations figure is rotated to an angle, the symbol constellations figure anglec of rotation of QPSK is 22.5 degree, the symbol constellations figure anglec of rotation of 16QAM is 11.25 degree, the symbol constellations figure anglec of rotation of 64QAM is 5.626 degree, and the symbol constellations figure anglec of rotation of 256QAM is 2.8125 degree; The code check of space-frequency coding device is 1.Mobile digital broadcast signal receiver in the single frequency network can take full advantage of the Cyclic Prefix characteristic of signal frame and the architectural characteristic of signal frame is carried out the baseband signal reception ﹠ disposal, processes comprising the time domain and frequency domain combined alternate analysis to signal frame head and signal frame body.
Characteristics of the present invention:
The present invention is the transmission plan that mix in a kind of time-domain and frequency-domain spatial domain.The empty generate pattern of modulating time domain discrete data sample block frequently of peak-to-average power ratio of falling of the present invention is modulated the time domain discrete data sample block choosing method with the empty frequency of peak-to-average power ratio that falls with minimum peak-to-average power ratio, but the very high large peak power signal probability of the maximum peak power that not only can take full advantage of ofdm signal is very low, the real part of the ofdm signal when number of sub carrier wave is larger (or imaginary part) is the characteristic of multiple Gaussian random process and whose amplitude obeys Rayleigh distribution, the amount of information of the required extra transmission of generate pattern of adopting is little, be easy to process the primary signal of recovering to obtain ofdm signal at receiver end, the orthogonal property that can not destroy sub-carrier signal simultaneously can not produce extra nonlinear distortion yet.Have periodic time domain in the signal frame of each mobile digital broadcast signal transmitter in the single frequency network and embed training sequence discrete sample block, the training sequence of each mobile digital broadcast signal transmitter in the single frequency network, the operational indicator sequence has pseudo-random characteristics, the training sequence of each mobile digital broadcast signal transmitter in the single frequency network, the operational indicator sequence has orthogonality each other, it is by falling the empty time domain discrete data sample block of frequently modulating of peak-to-average power ratio that the empty time domain discrete data sample block of frequently modulating of peak-to-average power ratio falls in the time domain embedding training sequence of each mobile digital broadcast signal transmitter in the single frequency network, time domain embeds training sequence discrete sample block and directly superposes and form, and these have guaranteed that each mobile digital broadcast signal receiver in the single frequency network can realize fast and accurately frame synchronization, 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 embedding training sequence as the protection interval fall the empty time domain discrete data sample block of frequently modulating of peak-to-average power ratio to form signal frame, can reduce the interference effect between the adjacent signals frame.The code element modulation is rotated the diversity that the mobile digital broadcast signal is provided with code element.Each different operational indicator sequence of each mobile digital broadcast signal transmitter in the single frequency network is comprising and unique each system parameters and business model information of expressing each mobile digital broadcast signal transmitter in the single frequency network, can so that digital television single-frequency network mobile digital broadcast transmission system can provide free television broadcasting, paid television broadcasting, Secret Information Transmission, multimedia value-added service etc. can control multi-service, satisfy social needs.Transmission method of the present invention has the equal power ratio of ebb, lock in time is short, clock jitter is little, anti-channel fading, anti-channel disturbance, can provide High Data Rate can control the plurality of advantages such as multi-service digital television single-frequency network mobile digital broadcast transmission.
Description of drawings
Fig. 1 is the embodiment schematic diagram according to signal transmission between the transmitter and receiver of method for transmitting mobile digital broadcast signals of single-frequency network of the present invention.
Fig. 2 is the embodiment schematic diagram that forms according to signal frame in the signals transmission between the transmitter and receiver of method for transmitting mobile digital broadcast signals of single-frequency network of the present invention.
Embodiment
Below in conjunction with accompanying drawing specific embodiments of the invention are described in detail.
The embodiment of signal transmission (supposing has N transmitter in the single frequency network) between the transmitter and receiver of the method for transmitting mobile digital broadcast signals of single-frequency network that proposes according to the present invention as shown in Figure 1, follows these steps to carry out:
1) the centre data manager of single frequency network converts the multi-medium data media data processor of flowing through to bit stream, and the scrambler sequence of utilizing feedback shift register to produce is carried out scrambling and processed to form the input data bit flow;
2) the network data management device of single frequency network will be inputted flow through code element modulation of data bit and be rotated in code element and form the FFT data block on the frequency domain, and FFT represents the fast discrete Fourier conversion, and the length of FFT data block is K; Code element is modulated to a kind of among QPSK, 16QAM, 64QAM and the 256QAM, and the symbol constellations figure mapping mode of code element modulation adopts the Gray code mapping; The code element rotation realizes by symbol constellations figure is rotated to an angle, the symbol constellations figure anglec of rotation of QPSK is 22.5 degree, the symbol constellations figure anglec of rotation of 16QAM is 11.25 degree, the symbol constellations figure anglec of rotation of 64QAM is 5.626 degree, and the symbol constellations figure anglec of rotation of 256QAM is 2.8125 degree;
3) to adopt code check be that 1 space-frequency coding device will be modulated in the FFT data block that frequency domain forms each mobile digital broadcast signal transmitter branch road in the single frequency network and form and emptyly frequently modulate the FFT data block to the network data management device of single frequency network, and the time synchronized of adjusting each mobile digital broadcast signal transmitter branch road is all frequently modulated the FFT data block to sky at one time and processed to guarantee all transmitters in the network;
4) each mobile digital broadcast signal transmitter in the single frequency network adopts IFFT that sky is modulated the FFT data block frequently and is transformed to the empty time domain discrete data sample block D that frequently modulates
Total, IFFT represents the fast discrete Fourier inverse transformation;
5) each mobile digital broadcast signal transmitter in the single frequency network is frequently modulated sky in order time domain discrete data sample block and is divided equally into two, the empty time domain discrete data sample sub-block D that frequently modulates
1Frequently modulate time domain discrete data sample sub-block D with sky
2, D
Total=[D
1, D
2];
6) each mobile digital broadcast signal transmitter in the single frequency network is modulated time domain discrete data sample sub-block D by the peak-to-average power ratio adjustment unit frequently to sky
1, the empty time domain discrete data sample sub-block D that frequently modulates
2Carry out that signal adds, subtracts, conjugate operation is processed and the synthetic new empty time domain discrete data sample block D that frequently modulates again
New, the new empty time domain discrete data sample block D that frequently modulates
NewAdopt following generate pattern to obtain, generate pattern 1 is D
New=[D
1, D
2], generate pattern 2 is
Generate pattern 3 is
Generate pattern 4 is
Generate pattern 5 is
Generate pattern 6 is
Generate pattern 7 is D
New=[D
* 1, D
2], generate pattern 8 is
Generate pattern 9 is
Generate pattern 10 is
Generate pattern 11 is
Generate pattern 12 is
Relatively 12 kinds of synthetic empty frequencies of generate pattern are modulated time domain discrete data sample block D
New, choose the empty frequency of peak-to-average power ratio that falls that wherein has minimum peak-to-average power ratio and modulate time domain discrete data sample block
And the empty time domain discrete data sample block of frequently modulating of peak-to-average power ratio will be fallen
The corresponding generate pattern information that adopts send to operational indicator sequence setting unit, wherein, D
* 1Expression is modulated time domain discrete data sample sub-block D frequently to sky
1Each empty modulate that time domain discrete data sample carries out that conjugate operation is processed frequently and the empty time domain discrete data sample sub-block of frequently modulating that obtains;
7) each mobile digital broadcast signal transmitter in the single frequency network is with the real part sequence of training sequence as sequence of plural training, the operational indicator sequence that operational indicator sequence setting unit is set is as the imaginary part sequence of sequence of plural training, consist of the discrete sample block of sequence of plural training in time domain, training sequence, the operational indicator sequence, the length of the discrete sample block of sequence of plural training all is X, the operational indicator sequence is comprising and unique each system parameters and business model information of expressing each mobile digital broadcast signal transmitter in the single frequency network, and X gets 512,1024, in 2048 one;
8) discrete sample block of the sequence of plural training that will consist of in time domain of each mobile digital broadcast signal transmitter in the single frequency network repeats continuously to form time domains 4 times and embeds training sequence discrete sample block on time domain, time domain embeds the length of training sequence discrete sample block and falls the empty length numerically equal of modulating time domain discrete data sample block frequently of peak-to-average power ratio, i.e. K=4 * X; When X got 512, K got 2048, and the frequency interval of corresponding subcarrier is got 4KHz; When X got 1024, K got 4096, and the frequency interval of corresponding subcarrier is got 2KHz; When X got 2048, K got 8192, and the frequency interval of corresponding subcarrier is got 1KHz;
9) each mobile digital broadcast signal transmitter in the single frequency network will fall the empty time domain discrete data sample block, time domain of frequently modulating of peak-to-average power ratio and embed training sequence discrete sample block and directly superpose and form time domain and embed training sequence and fall that peak-to-average power ratio is empty frequently modulates time domain discrete data sample block, as frame;
10) each mobile digital broadcast signal transmitter in the single frequency network is that frame head inserts time domain and embeds training sequence and fall peak-to-average power ratio empty frequently to modulate time domain discrete data sample block be frame with Cyclic Prefix as the protection interval, to form signal frame, the length of 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;
11) each mobile digital broadcast signal transmitter in the single frequency network adopts square root raised cosine filter that the signal pulse of signal frame is shaped;
12) each mobile digital broadcast signal transmitter in the single frequency network forms emission of radio frequency signals to the on-air radio channel with the baseband signal up-conversion to carrier wave;
13) the mobile digital broadcast signal receiver in the single frequency network detect to receive radiofrequency signal that each mobile digital broadcast signal transmitter in the single frequency network sends and its down-conversion is formed baseband signal, utilizes the Cyclic Prefix characteristic of signal frame and the architectural characteristic of signal frame to carry out the baseband signal reception ﹠ disposal.
According to the embodiment of signal frame formation (supposing has N transmitter in the single frequency network) in the signals transmission between the transmitter and receiver of method for transmitting mobile digital broadcast signals of single-frequency network of the present invention, as shown in Figure 2, implementation is as follows:
The centre data manager of single frequency network converts the multi-medium data media data processor of flowing through to bit stream, and the scrambler sequence of utilizing feedback shift register to produce is carried out scrambling and processed to form the input data bit flow.
The network data management device of single frequency network will be inputted flow through code element modulation of data bit and be rotated in code element and form the FFT data block on the frequency domain; Adopting code check is that 1 space-frequency coding device will be modulated in the FFT data block that frequency domain forms each mobile digital broadcast signal transmitter branch road in the single frequency network and form and emptyly frequently modulate the FFT data block, and the time synchronized of adjusting each mobile digital broadcast signal transmitter branch road is all frequently modulated the FFT data block to sky at one time and processed to guarantee all transmitters in the network; Through IFFT it is transformed to the empty time domain discrete data sample block of frequently modulating again, generates and choose the empty time domain discrete data sample block of frequently modulating of peak-to-average power ratio of falling that wherein has minimum peak-to-average power ratio by the peak-to-average power ratio adjustment unit and simultaneously the generate pattern information of the corresponding employing of institute is sent to operational indicator sequence setting unit.Code element is modulated to a kind of among QPSK, 16QAM, 64QAM and the 256QAM, and the symbol constellations figure mapping mode of code element modulation adopts the Gray code mapping; The code element rotation realizes by symbol constellations figure is rotated to an angle, the symbol constellations figure anglec of rotation of QPSK is 22.5 degree, the symbol constellations figure anglec of rotation of 16QAM is 11.25 degree, the symbol constellations figure anglec of rotation of 64QAM is 5.626 degree, and the symbol constellations figure anglec of rotation of 256QAM is 2.8125 degree.
Empty frequency is modulated the FFT data block and is comprised of subcarrier.Empty length of modulating the FFT data block frequently is K; When X got 512, corresponding K got 2048, and the frequency interval of corresponding subcarrier is got 4KHz; When X got 1024, corresponding K got 4096, and the frequency interval of corresponding subcarrier is got 2KHz; When X got 2048, corresponding K got 8192, and the frequency interval of corresponding subcarrier is got 1KHz.
Each mobile digital broadcast signal transmitter in the single frequency network 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, in the discrete sample block of time domain formation sequence of plural training, on time domain, it is repeated 4 times continuously again and form time domains 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 each mobile digital broadcast signal transmitter in the single frequency network form 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 Phase shift 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 each mobile digital broadcast signal transmitter in the single frequency network.
Each mobile digital broadcast signal transmitter in the single frequency network will fall the empty time domain discrete data sample block, time domain of frequently modulating of peak-to-average power ratio and embed training sequence discrete sample block and directly superpose and form time domain and embed training sequence and fall that peak-to-average power ratio is empty frequently modulates time domain discrete data sample block, as frame; Fall empty frequently modulation of peak-to-average power ratio at time domain embedding training sequence and insert Cyclic Prefix in the time domain discrete data sample block as the protection interval, the formation signal frame.Length as the Cyclic Prefix of protecting the interval is C; When X got 512, corresponding C got 1/4 of K size; When X got 1024, corresponding C got 1/8 of K size; When X got 2048, corresponding C got 1/16 of K size.
Each mobile digital broadcast signal transmitter in the single frequency network adopts square root raised cosine filter that the signal of signal frame is carried out pulse shaping.When X got 512, the corresponding signal to signal frame carried out the rolloff-factor of the square root raised cosine filter of pulse shaping and gets 0.1; When X got 1024, the corresponding signal to signal frame carried out the rolloff-factor of the square root raised cosine filter of pulse shaping and gets 0.05; When X got 2048, the corresponding signal to signal frame carried out the rolloff-factor of the square root raised cosine filter of pulse shaping and gets 0.025.
Each mobile digital broadcast signal transmitter in the single frequency network forms emission of radio frequency signals to the on-air radio channel with the baseband signal up-conversion to carrier wave.
Mobile digital broadcast signal receiver in the single frequency network detects and receives radiofrequency signal that each mobile digital broadcast signal transmitter in the single frequency network sends and its down-conversion is formed baseband signal, utilize the Cyclic Prefix characteristic of signal frame and the architectural characteristic of signal frame to carry out the baseband signal reception ﹠ disposal, process comprising the time domain and frequency domain combined alternate analysis to signal frame head and signal frame body.
The above has been described in detail specific embodiments of the invention by reference to the accompanying drawings, but the present invention is not limited to above-described embodiment, and in 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 method for transmitting mobile digital broadcast signals of single-frequency network is characterized in that it comprises the following steps:
1) the centre data manager of single frequency network converts the multi-medium data media data processor of flowing through to bit stream, and the scrambler sequence of utilizing feedback shift register to produce is carried out scrambling and processed to form the input data bit flow;
2) the network data management device of single frequency network will be inputted flow through code element modulation of data bit and be rotated in code element and form the FFT data block on the frequency domain, and the length of FFT data block is K; Code element is modulated to a kind of among QPSK, 16QAM, 64QAM and the 256QAM, and the symbol constellations figure mapping mode of code element modulation adopts the Gray code mapping; The code element rotation realizes by symbol constellations figure is rotated to an angle, the symbol constellations figure anglec of rotation of QPSK is 22.5 degree, the symbol constellations figure anglec of rotation of 16QAM is 11.25 degree, the symbol constellations figure anglec of rotation of 64QAM is 5.626 degree, and the symbol constellations figure anglec of rotation of 256QAM is 2.8125 degree;
3) to adopt code check be that 1 space-frequency coding device will be modulated in the FFT data block that frequency domain forms each mobile digital broadcast signal transmitter branch road in the single frequency network and form and emptyly frequently modulate the FFT data block to the network data management device of single frequency network, and the time synchronized of adjusting each mobile digital broadcast signal transmitter branch road is all frequently modulated the FFT data block to sky at one time and processed to guarantee all transmitters in the network;
4) each mobile digital broadcast signal transmitter in the single frequency network adopts IFFT that sky is modulated the FFT data block frequently and is transformed to the empty time domain discrete data sample block D that frequently modulates
Total
5) each mobile digital broadcast signal transmitter in the single frequency network is frequently modulated sky in order time domain discrete data sample block and is divided equally into two, the empty time domain discrete data sample sub-block D that frequently modulates
1Frequently modulate time domain discrete data sample sub-block D with sky
2, D
Total=[D
1, D
2];
6) each mobile digital broadcast signal transmitter in the single frequency network is modulated time domain discrete data sample sub-block D by the peak-to-average power ratio adjustment unit frequently to sky
1, the empty time domain discrete data sample sub-block D that frequently modulates
2Carry out that signal adds, subtracts, conjugate operation is processed and the synthetic new empty time domain discrete data sample block D that frequently modulates again
New, the new empty time domain discrete data sample block D that frequently modulates
NewAdopt following generate pattern to obtain, generate pattern 1 is D
New=[D
1, D
2], generate pattern 2 is
Generate pattern 3 is
Generate pattern 4 is
Generate pattern 5 is
Generate pattern 6 is
Generate pattern 7 is
Generate pattern 8 is
Generate pattern 9 is
Generate pattern 10 is
Generate pattern 11 is
Generate pattern 12 is
Relatively 12 kinds of synthetic empty frequencies of generate pattern are modulated time domain discrete data sample block D
New, choose the empty frequency of peak-to-average power ratio that falls that wherein has minimum peak-to-average power ratio and modulate time domain discrete data sample block
And the empty time domain discrete data sample block of frequently modulating of peak-to-average power ratio will be fallen
The corresponding generate pattern information that adopts send to operational indicator sequence setting unit, wherein, D
* 1Expression is modulated time domain discrete data sample sub-block D frequently to sky
1Each empty modulate that time domain discrete data sample carries out that conjugate operation is processed frequently and the empty time domain discrete data sample sub-block of frequently modulating that obtains;
7) each mobile digital broadcast signal transmitter in the single frequency network with training sequence as the real part sequence of sequence of plural training, operational indicator sequence that operational indicator sequence setting unit is the set imaginary part sequence as sequence of plural training, consist of the discrete sample block of sequence of plural training in time domain, the length of the discrete sample block of training sequence, operational indicator sequence, sequence of plural training all is X, and the operational indicator sequence is comprising and unique each system parameters and business model information of expressing each mobile digital broadcast signal transmitter in the single frequency network;
8) discrete sample block of the sequence of plural training that will consist of in time domain of each mobile digital broadcast signal transmitter in the single frequency network repeats continuously to form time domains 4 times and embeds training sequence discrete sample block on time domain, time domain embeds the length of training sequence discrete sample block and falls the empty length numerically equal of modulating time domain discrete data sample block frequently of peak-to-average power ratio, i.e. K=4 * X;
9) each mobile digital broadcast signal transmitter in the single frequency network will fall the empty time domain discrete data sample block, time domain of frequently modulating of peak-to-average power ratio and embed training sequence discrete sample block and directly superpose and form time domain and embed training sequence and fall that peak-to-average power ratio is empty frequently modulates time domain discrete data sample block, as frame;
10) each mobile digital broadcast signal transmitter in the single frequency network is that frame head inserts time domain and embeds training sequence and fall peak-to-average power ratio empty frequently to modulate time domain discrete data sample block be frame with Cyclic Prefix as the protection interval, to form signal frame, the length of Cyclic Prefix is C;
11) each mobile digital broadcast signal transmitter in the single frequency network adopts square root raised cosine filter that the signal pulse of signal frame is shaped;
12) each mobile digital broadcast signal transmitter in the single frequency network forms emission of radio frequency signals to the on-air radio channel with the baseband signal up-conversion to carrier wave;
13) the mobile digital broadcast signal receiver in the single frequency network detect to receive radiofrequency signal that each mobile digital broadcast signal transmitter in the single frequency network sends and its down-conversion is formed baseband signal, utilizes the Cyclic Prefix characteristic of signal frame and the architectural characteristic of signal frame to carry out the baseband signal reception ﹠ disposal.
2. by the method for transmitting mobile digital broadcast signals of single-frequency network of claim 1, it is characterized in that: the length X of the discrete sample block of the training sequence of each mobile digital broadcast signal transmitter in the described single frequency network, operational indicator sequence, sequence of plural training is got in 512,1024,2048.
3. by the method for transmitting mobile digital broadcast signals of single-frequency network of claim 2, it is characterized in that: described training sequence, operational indicator sequence form by a series of 1 or-1.
4. by the method for transmitting mobile digital broadcast signals of single-frequency network of claim 2, it is characterized in that: described training sequence, operational indicator sequence have pseudo-random characteristics.
5. by the method for transmitting mobile digital broadcast signals of single-frequency network of claim 2, it is characterized in that: described training sequence, operational indicator sequence have orthogonality each other.
6. by the method for transmitting mobile digital broadcast signals of single-frequency network of claim 1, it is characterized in that: described empty frequency is modulated the FFT data block and is comprised of subcarrier; When X got 512, sub-carrier number got 2048, and the frequency interval of subcarrier is got 4KHz; When X got 1024, sub-carrier number got 4096, and the frequency interval of subcarrier is got 2KHz; When X got 2048, sub-carrier number got 8192, and the frequency interval of subcarrier is got 1KHz.
7. by the method for transmitting mobile digital broadcast signals of single-frequency network of claim 1, it is characterized in that: the length C value of described Cyclic Prefix is relevant with the X value; 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.
8. press the method for transmitting mobile digital broadcast signals of single-frequency network of claim 1, it is characterized in that: the baseband signal reception ﹠ disposal that described single frequency network mobile digital broadcast signal receiver carries out, one of them step are that the time domain and frequency domain combined alternate analysis of signal frame head and signal frame body is processed.
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| Title |
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| 王劲涛等.数字电视广播的单频网实现及场地实验.《清华大学学报（自然科学版）》.2005,第45卷(第10期),1385-1388. * |
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