CN1549591A - Simultaneous multi-carrier wave spread spectrum digital TV transmission system with minimum peak-level ratio - Google Patents
Simultaneous multi-carrier wave spread spectrum digital TV transmission system with minimum peak-level ratio Download PDFInfo
- Publication number
- CN1549591A CN1549591A CNA031178855A CN03117885A CN1549591A CN 1549591 A CN1549591 A CN 1549591A CN A031178855 A CNA031178855 A CN A031178855A CN 03117885 A CN03117885 A CN 03117885A CN 1549591 A CN1549591 A CN 1549591A
- Authority
- CN
- China
- Prior art keywords
- time
- domain
- data
- frequency
- frequency domain
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Abstract
The system uses FFT conversion as time-frequency constrained correlation operation to form effective interdependent for each carrier of frequency domain with utilization time domain constrained linear correlator and frequency domain mapping under condition that sampling ratio of time-frequency constraint and OFDE is a simple integer ratio so that low peak-flat ratio is obtained by utilizing signal-noise ratio increase in 'phase growth frequency band' to overcome signal-noise ratio decrease in 'phase decline frequency band'.
Description
Technical field:
The invention belongs to TV technology, it is particularly related to digital TV ground transmission technology and WiMAX digital modulation transmission technology.
Background technology:
The digitlization transmission technology of TV signal, the digit transmission method in channels such as satellite and cable TV is resolved.And aspect its most important terrestrial wireless transmission, its transmission quality, reliability and coverage are subjected to the influence and the restriction of the following factor:
(1) interference of multipath (city housing-group, hills, mountain area) transmission;
(2) overland propagation is stopped by landform, high building covers and the influence of sea surface reflection ripple;
(3) be subjected to analog/digital shared channel and the adjacent interference of channel frequently;
(4) disturbed by the ground sporadic impulse noise, particularly even more serious at hyperfrequency (VHF) wave band;
(5) when move receiving, what be subjected to that Doppler frequency shift, motion (space/time) decline, shade cover has a strong impact on;
For overcoming many difficulties of above-mentioned terrestrial transmission, overcoming the multipath interference, adopt single frequency network to solve channel allocation and solving aspects such as moving reception especially, each country has researched and proposed different system schemas.Terrestrial DTV transmission standard/scheme both domestic and external is existing:
1) U.S.'s terrestrial DTV transmission standard ATSC (implementing) from nineteen ninety-five
2) European terrestrial DTV transmission standard DVB-T (implementing) from 1997
3) Japanese terrestrial DTV transmission standard ISDB-T (to be performed)
4) the terrestrial DTV transmission plan DMB-T of Tsing-Hua University
In the existing at home and abroad digital TV ground radio transmitting method, the ATSC scheme of the U.S. occurs the earliest, adopts the 8VSB modulation technique, belongs to single-carrier modulated, fails to solve mobile reception problem.The DVB-T scheme in Europe occurs a little later, adopt the COFDM modulation, belong to multi-carrier modulation, solved the problem of mobile reception, but the signal when walking in high-speed mobile with in the covering of city housing-group is reentried and again stationary problem separate never goodly, and be difficult to make up honeycomb single frequency network (Cellular SFN).The ISDB-T scheme of Japan is similar with the scheme in Europe, and its modulator approach is (BST) OFDM, is made up of one group of common fundamental frequency piece that is called the BST section, also belongs to multi-carrier modulation.The DMB-T scheme of China Tsing-Hua University also belongs to multicarrier system.The peak-to-average ratio of lower data transfer rate and higher transmitted waveform is the critical defect of existing ofdm system.
Problem at above four terrestrial digital television systems existence, adopt new technological means, according to China's national situation, take into full account the covering in Chinese topography and geomorphology, administrative division and city, rural area and the present situation of radio and television services, be conceived to development long-range, stable, that continue, propose ground digital TV transmission system a kind of novelty, high efficiency, high reliability.
Fig. 1 provided the inventor " synchronous multicarrier spread spectrum surface digital TV transmission system " patent application (application number: 01108788.9, the applying date: the basic principle block diagram August 21 calendar year 2001).It comprises multicarrier, the time-fixed second precise synchronization four parts of the parallel spread spectrum of frequency, cycle continuous pilot, transport stream.Wherein adopt multi-transceiver technology (4K pattern OFDM) to overcome multipath effect and set up single frequency network (SFN) system.During employing-quick OFDM sign synchronization that frequently parallel spread spectrum (CDMA) brings overcomes and walks when receiving signal reentry and difficulty, the doppler frequency shift tracking problem when adopting cycle continuous pilot technology to solve high-speed mobile and motion decline synchronously again between covering.Adopt fixed second precise synchronization technology of system transport stream to solve in the difficulty of setting up honeycomb single frequency network (Cellular SFN) transmission system, cover covering problem down in order to solve the city housing-group, and for the data passback required synchronously, regularly, locate technological means be provided.It comprises following three parts, Part A: the frequency domain multicarrier is handled (COFDM) part; Part B: time domain CDMA part; Part C: single frequency network (SFN) code stream sync section.Wherein Part A comprise energy dissipation 3, outer encoder 4, external interleaver 5, inner encoder 6, interleaver 7, QAM mapper 8, frame adaptive 9, OFDM11, protection insert at interval/time inserts 12, D/A13, channel filtering 14, front end 15, scattered pilot and TPS signal 10; Part B comprises a second clock PLL timer 16, time service symbolic information formation 17, time domain CDMA synchronous time domain continuous pilot 18; Part C comprises: code stream time delay adjustment 1, time service bag detect and code stream time delay control 2.
This scheme adopts multi-transceiver technology (4K pattern OFDM) to overcome multipath effect and sets up single frequency network (SFN) system.OFDM (OFDM) adopts a lot of sub-channel parallel Digital Transmission, each subchannel adopts OFDM, expanded the subchannel transmission symbol intervals greatly, the bandwidth of subchannel is less than coherence bandwidth, adopt many level/QAM modulation technique, thereby the frequency selectivity distortion ability that very high band efficiency is arranged and resist multipath.Can also resist the random error that the interference of burst error and AWGN causes effectively in conjunction with chnnel coding and time-frequency interleaving technology efficiently.Adopt the OFDM system to have the following advantages:
When 1, realizing in system, OFDM is divided into many narrowband carriers with wide bandwidth, carries out parallel transmission, can reduce the chip transmission rate of each subcarrier.Adopt guardtime interval (TGI) to remove intersymbol interference (ISI) effectively simultaneously, disturb thereby overcome the multipath that is shorter than TGI.
2, OFDM utilizes the orthogonality between subcarrier, can improve the availability of frequency spectrum effectively.
OFDM (OFDM) technology is a kind of multicarrier parallel transmission system, it replaces common serial pulses sequence sequential to transmit the transmission simultaneously on N subcarrier of N element number, thereby has prevented the intersymbol interference that causes because of frequency selective fading effectively.Fig. 2 provides the spectrum diagram of OFDM, is zero at the central point of each subchannel from the interference of other subchannel as seen from the figure.
But for OFDM (OFDM) multi-carrier modulation commonly used, its significant deficiency is that each subband spectrum value is for independent.Promptly in the OFDM modulation system, its source data is independent assignment on each subcarrier in frequency domain, and when channel has under the situation that frequency selectivity disturbs, the signal to noise ratio on some " subband mutually disappears " reduces and causes information dropout.Though simultaneously the signal to noise ratio on other " phase eldest son with " increases to some extent, because the information of each subcarrier is independent and quantize assignment, the amount of information of high s/n ratio subband institute load does not increase, and can not bring compensation generally.The adaptive bit that employing has feedback distributes, and is a kind of method of dealing with problems.But this method is not suitable for broadcasting channel.
In coding frequency division multiplexing (COFDM) system, adopted means such as ISN coding to strengthen the correlation of each subband data.But since each sub-band to carry bit number identical, and fail to change its basic situation.High s/n ratio gain on some " phase eldest son with " is so can not help low signal-to-noise ratio loss on other " subband mutually disappears " effectively because of quantizing assignment.This is the significant deficiency of OFDM, COFDM multi-carrier transmission system.For the multicarrier system can better be played a role, key will be established a kind of effective frequency domain tied mechanism exactly, makes under the situation that has the frequency selectivity interference, can help each other between the signal to noise ratio profit and loss of each subband.
Second significant deficiency of OFDM/COFDM multicarrier system is that peak-to-average ratio is too high.
" peak-to-average ratio (peak power/average power) " is an important parameter of modulated signal in the communication system.The modulated signal of high peak-to-average ratio will make the power utilization deficiency of transmitter, and make the linearity to transmitter require to increase.Peak-to-average ratio Rp-a is defined as: the ratio of the peak power Ppeak of the modulated signal that is transmitted and its average power Paver
Rp-a＝Ppeak/Paver
As shown in Figure 3.
When the peak power of modulated signal was higher, for adapting to the power requirement in this moment, transmitter was had to do very big power and is reserved (rollback), and can only keep less operate power in remaining overwhelming majority time.This just makes the margin of power of transmitter well do not brought into play, has increased the operating cost of transmitter.Otherwise, do not reserve if do not make suitable power, then modulated signal promptly can be urged to transmitter the power saturation region during higher-wattage, brings great nonlinear distortion to signal, is equivalent to have formed non-linear Intermodulation Interference in the very big transmitter passband.The elimination of the non-linear Intermodulation Interference of transmitter is an extremely difficult job, and it needs very complicated correction of non-linear distortions circuit.At present, sufficient back-off remain reduce the transmitter nonlinear Intermodulation Interference effective way, the low peak-to-average ratio of modulated signal is still one of important indicator of communication system.The time domain waveform of multicarrier system is because the independent assignment of each subcarrier spectrum becomes random waveform.Its probability distribution increases with carrier number gets normal distribution very soon.The peak-to-average ratio of OFDM/COFDM multicarrier system (normal distribution) is high by about 4 to 6db than the peak-to-average ratio of single carrier (evenly distributing).The coupling of the power output of the flat comparison in peak transmitter, third order intermodulation inhibition, spectrum mask has been brought huge difficulty.For peacock, high linearity becomes the key issue of multicarrier system.Therefore, introducing appropriate " time-frequency constraint " is exactly closely related the depending on each other for existence of spectrum value that makes each subcarrier, be provided with reasonably " time-frequency constraint " at first should consider to have using value, first-selection promptly reduces the peak-to-average ratio of system.Making time domain waveform have " minimum peak-to-average ratio " is exactly a kind of concrete constraint to each sub-carrier frequency domain value.
Summary of the invention:
The SMCC digital television transmission system that the purpose of this invention is to provide a kind of minimum peak-to-average ratio, this system can make the spectrum value of (1) each subcarrier closely related, depend on each other for existence; (2) spectrum value of each subcarrier high accuracy assignment (practicality in by the maximum word length of fixing a point) as far as possible in the frequency domain is to guarantee to provide more information at this subband when having high s/n ratio to gain; (3) satisfy minimum peak-to-average ratio.
The present invention program adds minimum peak-to-average ratio in the digital television broadcasting system of existing " SMCC system " " time-frequency retrains correlator 24 and high accuracy frequency domain mapping 19 realizes.
Composition of the present invention:
The invention provides a kind of SMCC digital television transmission system of minimum peak-to-average ratio, adopt multi-carrier spread spectrum digital TV ground transmission channel adapter, as shown in Figure 4, described adapter comprises: Part A: the frequency domain multicarrier is handled (COFDM) part; Part B: time domain CDMA part; Part C: single frequency network (SFN) code stream sync section; Wherein Part A comprise energy dissipation 3, outer encoder 4, external interleaver 5, inner encoder 6, interleaver 7,, frame adaptive 9, OFDM 11, protection insertions/time insertion 12, D/A13, channel filtering 14, front end 15, scattered pilot and TPS signal 10 at interval; Part B comprises a second clock PLL 16, time service symbolic information formation 17, time domain CDMA synchronous time domain continuous pilot 18; Part C comprises: code stream time delay adjustment 1, time service bag detect and code stream time delay control 2, it is characterized in that also having comprised time-domain constraints linear correlation device 24 and high accuracy frequency domain mapping 19.Shine upon 19 by the data flow of interleaver 7 output through time-domain constraints linear correlation device 24 and high accuracy frequency domain and laggardly go into frame adaptive 9.
Innovation part of the present invention is time-domain constraints linear correlation device 24, high accuracy frequency domain mapping 19, and remainder is same as the prior art.
The time-domain constraints linear correlation device 24 of " minimum peak-to-average ratio " adopts general DFT (FFT) module, and its structure is as described below.
For time series, no matter be that one dimension evenly distributes (corresponding to VSB) or evenly distribution (corresponding to QAM) of two dimension, under discrete situation, its peak-to-average ratio is by 1.0 (2VSB when VSB, the increase of QAM exponent number, 4QAM) level off to 3.0 (about 5db) very soon, consider in the practicality that " minimum peak-to-average ratio " is 6db.Choosing one dimension in the time domain evenly distributes (real number centrifugal pump) or two dimension evenly distributes, (plural I/Q centrifugal pump) is the source data random value scope of native system, promptly obtains the time series with " minimum peak-to-average ratio ".Utilize DFT (FFT) to convert it to frequency domain, and, promptly be applicable to the object of the invention by maximum fixed point word length (the 16 or 24) assignment that its digital processes branch uses.When having like this, " minimum peak-to-average ratio "-the frequency domain assignment problem of frequency constraint obtains satisfactory solution from the angle of engineering practice.At this moment, distribute to the value of each subcarrier in frequency domain and approach normal distribution, the frequency domain assignment that each subband is determined is by the transmission of encoding of system's fixed-point calculation maximum number of digits.
The block diagram of time-domain constraints linear correlation device 24 as shown in Figure 5.It is by serial/parallel conversion 20, is mapped as many level of one dimension or two-dimentional I/Q data block 21, linear crossing combination 22, and transform domain data block 23 is formed.
When source traffic (serial bit stream) order arrives,, be rearranged for the data cell that some bit combinations constitute through serial/parallel transducer (as shown in Figure 6).
1). the course of work of serial/parallel conversion (20) is as follows:
B1 to bn is the shift register of n bit (the n value is generally 2 to 8), and each bk can deposit 1 bit information.Under the control of bit clock, each bit of source data enters bn to b1 one by one, and moves to right gradually.Behind n the clock, there be n bit all to move into the shift register of b1 to bn.Simultaneously, bit clock has obtained a data clock (being that every n bit clock produces a data clock) again by " removing n " frequency divider.In this moment, next stage will be taken out and be sent to whole n data of the shift register of b1 to bn (being called n bit parallel data) simultaneously.The continuous circulation of this process has formed " the n bit stream Bi of parallel data ", and wherein B represents n bit parallel data, and i represents the continuous variation that this parallel data increases in time.
2). each the n bit parallel data among the n bit stream Bi of parallel data are referred to as data cell.Data cell is further passed through suitable coding and mapping, is converted into the data block 21 that the many level of one dimension or two dimension plural number (I/Q) data cell are formed, and its course of work is as follows:
N bit to the process of one dimension (real number) or two dimension (I/Q, plural number) mapping is described below.If n=3, promptly each parallel data is 3 bits.To the situation of one dimension, the desirable 8 kinds of values of the data of this 3 bit are as first row of Figure 14.Corresponding every kind of value makes it be mapped as an integer, promptly among Fig. 7 on the longitudinal axis equally distributed 8 points { 7 ,-5 ,-3 ,-1,1,3,5, more, this point represents that mapping value can be taken as one of above-mentioned 8 kinds of level (many level, relative unit) among the 7}.
To the situation of two dimension, need get two data continuously, two 3 Bit datas are promptly arranged.The data of first 3 bit can be as preceding getting 8 kinds of values (I), the data of second 3 bit also can be got 8 kinds of values (Q) arbitrarily, it are mapped as a plural number, i.e. (I among Fig. 8 again, Q) (answer) integral point (illustrating when n=3, totally 8 * 8=64 point) one of in the equally distributed lattice point on the plane.So just finished mapping.When n is worth for other, can analogize.Can design " corresponding one by one " table of different mappings, also can adopt the mapping of non-uniform Distribution.
3). the course of work of linear crossing combination 22 and transform domain data block 23 is:
To having finished each data cell of mapping in the data block, not in handling as present multicarrier, simply it is mapped as the frequency domain value of each subcarrier, but (for example can adopt Walsh-Hadamard conversion-WHT according to certain rules to all data cells in the data block again, its coefficient is simple integer ± 1, and compound mode is an addition, subtraction operation; Also can use FFT) respectively get the combined crosswise (or being called linear transformation) 22 that certain ratio is carried out linearity, the data that obtained have formed new transform domain data 23 (referring to Fig. 4).This linear crossing compound mode is referred to as multicarrier " time-frequency constraint linear correlation " and handles.
In sum, each transform domain data promptly connects each other with each data in closely-related form and the former data block.As frequency domain data, can make the frequency domain value of each subcarrier closely related it, depend on each other for existence.Like this, certain subcarrier is interfered in channel, and when its entrained data became unreliable (subband mutually disappears), the data of its transmission still can relatedly be recovered by the data that are transmitted in other subbands.
Need to prove:
1). because the transform domain data are not directly used in the time domain transmission, so to after " time-frequency constraint linear correlation " processing, the data that obtained in the transform domain needn't be considered its distribution character.But, " time-frequency constraint linear correlation " processing with multicarrier of " minimum peak-to-average ratio " characteristic must possess following character: these transform domain data can access the time domain modulated signal with good peak-to-average ratio after handling through the contrary Fourier transform (IFFT) of multicarrier.Therefore, it is very rational adopting DFT (FFT) to handle as " time-frequency constraint linear correlation ".
2). the length of the data block/transform domain data block of " time-frequency constraint linear correlation " processor 24 front and back is consistent.Because the transform domain data will be used as the frequency domain value of each subcarrier and assignment, and have various requisite pilot tones in multicarrier Central Plains, the position of this pilot tone must be reserved.Thereby the length of transform domain data block should equal total sub-carrier number and deduct the pilot tone number that should add, as shown in Figure 4." time-frequency constraint linear correlation " handles resulting transform domain data block, intert added various pilot tones after, promptly be sent to contrary Fourier transform (IFFT) module to finish multi-carrier modulation (OFDM).
The implementation method of high accuracy frequency domain mapping 19 is: give IFFT module in the OFDM module 11 through the transform domain data block that obtains behind " time-frequency constraint linear correlation " processor 24 by the plural assignment of the employed maximum fixed point word length of its DSP part (12,16 or 24 etc.).Being 12 with maximum fixed point word length is example, and every subcarrier promptly is on horizontal stroke/longitudinal axis at frequency domain equally distributed 4096 in the high accuracy mapping of frequency domain
2Individual complex points 2048 ,-2047 ... ,-5 ,-4 ,-3,-2 ,-1,0,1,2,3,4 ..., 2045,2046,2047}x{-j2048 ,-j2047, ,-j5 ,-j4 ,-j3 ,-j2 ,-j, 0, j, j2, j3, j4 ... j2045, j2046, more, mapping value can be taken as one of above-mentioned level (I/Q level, relative unit) among the j2047}.
The broadcast system (as shown in Figure 4) of the minimum peak-to-average ratio of forming after the processing through time-domain constraints linear correlation device 24, high accuracy frequency domain mapping 19 has following characteristics:
This " synchronous many single carriers spread spectrum of minimum peak-to-average ratio " system has kept all advantages of multicarrier system, simultaneously, it creatively utilized the FFT conversion as the time-frequency retrains related operation, each subcarrier to frequency domain has formed effective mutual interdependency, thereby make system in the frequency selectivity passage, the signal to noise ratio that can effectively utilize " phase eldest son's frequency band " increases the signal to noise ratio that overcomes " sub-band mutually disappears " and reduces, thereby total signal to noise ratio of system is remained unchanged, help that inhibit signal detects thresholding in the frequency selectivity passage.Thereby, the native system compatibility advantage separately of many/single carrier standard, comprise low peak-to-average ratio, robustness, high performance-price ratio etc., and be easy to the mode of operation transition that mixes to " synchronous multicarrier " and " synchronously single carrier ".Simultaneously, different mode, the parameter options of " SMCC of minimum peak-to-average ratio " system also can be used for transmission standards such as cable digital TV, terrestrial DTV, microwave digital television transmission, reach unified wired (Cable)/ground (Terrestrial)/microwave (MMDS) digital television transfer standard, the optimal objective of " China Digital TV transmission standard " system of foundation unification and " transmission and covering unification ".
Description of drawings:
Fig. 1 is the digital television broadcasting system schematic diagram of " SMCC system ".
Wherein divide among the figure three part Part A frequency domain multicarriers handle (COFDM) partly, Part B time domain CDMA part and Part C single frequency network (SFN) code stream sync section.Insertions/the times insert at interval, 13 expression D/A, 14 expression channel filterings, 15 expression front ends, 10 represent scattered pilot and TPS signals for 3 expression energy dissipation, 4 expression outer encoders, 5 expression external interleavers, 6 expression inner encoders, 7 expression interleavers, 8 expression mapping modulators, 9 expression frame adaptives, 11 expression OFDM, 12 expression protections; 16 expression second clock PLL timers, 17 expression time service symbolic information form, 18 expression time domain CDMA synchronously/the time domain continuous pilot; 1 expression code stream time delay adjustment, 2 expression time service bags detect and the control of code stream time delay.
Fig. 2 is the frequency spectrum of OFDM
Be zero from the interference of other subchannel as can be seen from the figure at the central point of each subchannel.
Fig. 3 is modulated signal " peak-to-average ratio " definition
Wherein, P
PeakThe expression signal peak, P
PaverThe mean value of expression signal.
Fig. 4 is the SMCC system principle diagram of minimum peak-to-average ratio
Wherein divide among the figure three part Part A frequency domain multicarriers handle (COFDM) partly, Part B time domain CDMA part and Part C single frequency network (SFN) code stream sync section.Insertions/the times insert at interval, 13 expression D/A, 14 expression channel filterings, 15 expression front ends, 10 represent scattered pilot and TPS signals for 3 expression energy dissipation, 4 expression outer encoders, 5 expression external interleavers, 6 expression inner encoders, 7 expression interleavers, 24 expression time-domain constraints linear correlation devices, 19 expression high accuracy frequency domains mappings, 9 expression frame adaptives, 11 expression OFDM, 12 expression protections; 16 expression second clock PLL timers, 17 expression time service symbolic information form, 18 expression time domain CDMA synchronously/the time domain continuous pilot; 1 expression code stream time delay adjustment, 2 expression time service bags detect and the control of code stream time delay.
Fig. 5 is a time-frequency constraint linear correlation.
The wherein serial/parallel conversion of 20 expressions, 21 expressions are mapped as many level of one dimension or two-dimentional I/Q data block, 22 expression linear crossing combinations, 23 expression transform domain data blocks.
Fig. 6 is serial/parallel transducer.
Wherein n is the parallel data figure place, b1, b2 ... bn-1, bn are register, and ÷ n obtains data clock with clock signal n frequency division.
Fig. 7 is the mapping value under the one-dimensional case.
Fig. 8 is two dimension (I, Q) an equally distributed mapping value on the plane.
Fig. 9 is a 8K mode parameter table
This figure has listed that GI counts under the 8K pattern, the OFDM symbol is counted, the DFT symbol is counted; Wherein Tg is the time span of GI.OFDM symbol total length=GI length+DFT symbol lengths (1072.566 us, 9216 points), this mode prioritization are used for the Da Qu single frequency network and make up, and shortwave/ultrashort wave over the horizon wideband digital communication, aerial remote supervision system etc.
Figure 10 is a 4K mode parameter table
This figure has listed that GI counts under the 4K pattern, the OFDM symbol is counted, the DFT symbol is counted; Wherein Tg is the time span of GI.OFDM symbol total length=GI length+DFT symbol lengths (536.283 us, 4608 points), this mode prioritization is used for ground synchronous honeycomb single frequency network structure etc.
Figure 11 is a 2K mode parameter table
This figure has listed that GI counts under the 2K pattern, the OFDM symbol is counted, the DFT symbol is counted; Wherein Tg is the time span of GI.OFDM symbol total length=GI length+DFT symbol lengths (268.141 us, 2304 points), this mode prioritization are used for ground synchronous honeycomb single frequency network and make up microwave terrestrial transmission, surface surveillance system etc.
Figure 12 is a 1K mode parameter table
This figure has listed that GI counts under the 1K pattern, the OFDM symbol is counted, the DFT symbol is counted; Wherein Tg is the time span of GI.OFDM symbol total length=GI length+DFT symbol lengths (134.071 us, 1152 points), this mode prioritization are used for the microwave terrestrial transmission, tv wireless covers extension, surface surveillance system etc.
Figure 13 is a 0.5K mode parameter table
This figure has listed that GI counts under the 0.5K pattern, the OFDM symbol is counted, the DFT symbol is counted; Wherein Tg is the time span of GI.This mode prioritization of OFDM symbol total length=GI length+DFT symbol lengths (67.035 us, 576 points) is used for cable digital TV transmission, ground mobile monitoring system etc.
Figure 14 is the mapping value of parallel data when being 3 bits
Figure 15 is a 4K Mode A parameter list
This figure has listed that GI counts under the 4K Mode A, the OFDM symbol is counted.This is a kind of comparatively special mode of operation, and it only contains a kind of GI at interval, and with simplified system, its OFDM symbol total length is 470.8097928 us, DFT 4608 points, and bandwidth of operation is 7.612416MHz.This mode prioritization is used for ground synchronous honeycomb single frequency network structure etc.
Embodiment:
All modules among the present invention can realize on existing general dsp (Digital Signal Processor) (as the TMS320C62 series or the TMS320C64 series DSP of TI company).Wherein module 11 can adopt a DSP to realize separately, and the function of other module realizes on another piece DSP.
Below be the major parameter of the embodiment of the invention:
Nominal band width: 8MHz
Effective band width W: 7.63776MHz (about 5% channel is isolated width)
Nyquist sampling clock T
N: 0.130928439 us=1/W
Handle bandwidth expansion factor α: 0.125 (1/8)
(under the general situation, 1+ α must be taken as simple integer than Za/Zb, Za＞Zb.Its accepted value is 2/1,3/2,4/3,5/4,7/6,8/7,9/7,9/8,11/8,10/9,11/9 etc.)
Handle bandwidth W α: 8.59248MHz=(1+ α) effective band width W
(1+ α) times over-extraction sample clock T α: 0.116380835 us=T
N/ (1+ α)=1/W α
DFT (or FFT) counts: N---adopts Nyquist to handle;
(1+ α) N---adopts the bandwidth extension process.So-called bandwidth extension process is meant in Nyquist handles, and meets the sampling rate requirement though it handles bandwidth, and loss of information is not also considered the engineering construction requirement of spectrum shaping and filtering.In the bandwidth extension process, make and handle that bandwidth is widened and the inhibit signal bandwidth is constant simultaneously to improve sample rate.A rhapsody frequency domain initial value in signal bandwidth and the expansion bandwidth in a rhapsody frequency domain null value.The time domain waveform of Chan Shenging had both had good spectrum shaping like this, and was easy to carry out Filtering Processing.
Carrier wave mode of operation among the present invention can be selected following mode:
8K pattern (8192 point/9216 DFT) (see figure 9)
4K pattern (4096 point/4608 DFT) (see figure 10)
4K Mode A (3584 point/4608 DFT) (seeing Figure 15)
2K pattern (2048 point/2304 DFT) (seeing Figure 11)
1K pattern (1024 point/1152 DFT) (seeing Figure 12)
0.5K pattern (512 point/576 DFT) (seeing Figure 13)
The DFT symbol lengths that it is corresponding:
8K pattern (8192 point/9216 DFT) 1072.565778 us
4K pattern (4096 point/4608 DFT) 536.2828892 us
4K Mode A (3584 point/4608 DFT) 470.8097928 us
2K pattern (2048 point/2304 DFT) 268.1414446 us
1K pattern (1024 point/1152 DFT) 134.0707223 us
0.5K pattern (512 point/576 DFT) 67.03536115 us
Corresponding every kind of mode of operation all has a series of available guardtimes (GI) pattern and time corresponding length T g thereof at interval, to adapt to the time delay protection requirement of under the various mode of operations multipath being disturbed, as Fig. 9, Figure 10, Figure 11, Figure 12, shown in Figure 13.
GI listed in Fig. 9, Figure 10, Figure 11, Figure 12, Figure 13 counts, the OFDM symbol is counted, DFT symbolic point number average calculates with over-extraction sample clock T α, and the time length of GI is designated as Tg.Figure 15 is the 4K Mode A, and it only contains a kind of GI at interval.
All GI optional parameters items have all guaranteed to have an integer OFDM sign field and an integer TS bag within 1 second, it is synchronous to be beneficial to system-level TS stream code stream, and this makes up the system synchronization of simplifying " honeycomb single frequency network " and is very important.
Above system (system parameters has adopted the parameter value among Fig. 9, Figure 10, Figure 11, Figure 12, Figure 13, Figure 15) is through having certain correlation between the emulation of the computer software proof spectrum value by each subcarrier after the processing of module 24 and module 19, thereby improved the anti-frequency domain selectivity decline performance of system and reduced the peak-to-average ratio of transmitter.
Claims (4)
1, a kind of SMCC digital television transmission system of minimum peak-to-average ratio adopts multi-carrier spread spectrum digital TV ground transmission channel adapter, and described adapter comprises: Part A: the frequency domain multicarrier is handled (COFDM) part; Part B: time domain CDMA part; Part C: single frequency network (SFN) code stream sync section; Wherein Part A comprises energy dissipation (3), outer encoder (4), external interleaver (5), inner encoder (6), interleaver (7), frame adaptive (9), OFDM (11), protection insertion/time insertion (12), D/A (13), channel filtering (14), front end (15), scattered pilot and TPS signal (10) at interval; Part B comprises that a second clock PLL (16), time service symbolic information form (17), time domain CDMA synchronous time domain continuous pilot (18); Part C comprises: the code stream time delay is adjusted (1), the time service bag detects and code stream time delay control (2), it is characterized by and also comprise time-domain constraints linear correlation device (24) and high accuracy frequency domain mapping (19), the data flow of interleaver (7) output shines upon through time-domain constraints linear correlation device (24) and high accuracy frequency domain that (19) are laggard goes into frame adaptive (9).
2, the SMCC digital television transmission system of a kind of minimum peak-to-average ratio according to claim 1, it is characterized in that described time-domain constraints linear correlation device (24) is by serial/parallel conversion (20), be mapped as many level of one dimension or two-dimentional I/Q data block (21), linear crossing combination (22), transform domain data block (23) is formed, by the data flow of interleaver (7) output is that serial bit stream is when arriving in order, through serial/parallel conversion (20), by (21) parallel data is mapped as many level of one dimension or two-dimentional I/Q data block then, again all data cells in the data block are respectively got certain ratio according to certain rules and carry out linear linear crossing combination (22), the data that obtained have formed new transform domain data (23), described " according to certain rules " can adopt Walsh-Hadamard conversion-WHT, and (its coefficient is simple integer ± 1, compound mode just adds, subtract computing), discrete (fast) Fourier transform DFT (FFT) or other linear rule.
3, the SMCC digital television transmission system of a kind of minimum peak-to-average ratio according to claim 1 is characterized in that described high accuracy frequency domain mapping (19) is by giving discrete (fast) in the OFDM module (11) against Fourier transform IDFT (IFFT) module through the transform domain data that obtain behind " time-frequency constraint linear correlation " processor (24) by the plural assignment of the employed maximum fixed point word length of its DSP part (12,16 or 24 etc.); It is example that the IFFT module is 12 with maximum fixed point word length, and every subcarrier promptly is on horizontal stroke/longitudinal axis at frequency domain equally distributed 4096 in the high accuracy mapping of frequency domain
2Individual complex points 2048 ,-2047 ... ,-5 ,-4 ,-3,-2 ,-1,0,1,2,3,4 ..., 2045,2046,2047}x{-j2048 ,-j2047, ,-j5 ,-j4 ,-j3 ,-j2 ,-j, 0, j, j2, j3, j4,, j2045, j2046, more, mapping value can be taken as one of above-mentioned level (the I/Q level is a relative unit) among the j2047}.
4, the SMCC digital television transmission system of a kind of minimum peak-to-average ratio according to claim 1, it is characterized in that specific simple integer being arranged than concerning 1 between the sampling rate (being that conversion is counted) of IDFT (IFFT) conversion in the sampling rate (being that conversion is counted) of DFT (FFT) conversion that time-domain constraints linear correlation device (24) is adopted and module OFDM (11), adopted: (1+a), wherein its accepted value of 1+a is 2/1,3/2,4/3,5/4,7/6,8/7,9/7,9/8,11/8,10/9,11/9 etc.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03117885 CN1274150C (en) | 2003-05-19 | 2003-05-19 | Simultaneous multi-carrier wave spread spectrum digital TV transmission system with minimum peak-level ratio |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03117885 CN1274150C (en) | 2003-05-19 | 2003-05-19 | Simultaneous multi-carrier wave spread spectrum digital TV transmission system with minimum peak-level ratio |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1549591A true CN1549591A (en) | 2004-11-24 |
| CN1274150C CN1274150C (en) | 2006-09-06 |
Family
ID=34320683
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 03117885 Expired - Fee Related CN1274150C (en) | 2003-05-19 | 2003-05-19 | Simultaneous multi-carrier wave spread spectrum digital TV transmission system with minimum peak-level ratio |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1274150C (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100446559C (en) * | 2004-12-30 | 2008-12-24 | 电子科技大学 | Framing method of isomorphic data in two domains in use for ground digital TV transmission system |
| CN101383803B (en) * | 2008-10-27 | 2010-10-27 | 宁波大学 | Digital television ground broadcast transmitter space-frequency modulation method based on embedded training sequence |
| CN101383805B (en) * | 2008-10-27 | 2010-12-01 | 宁波大学 | Digital television ground broadcast transmitter modulation method having time-domain training sequence |
| CN101383806B (en) * | 2008-10-27 | 2010-12-22 | 宁波大学 | Digital television ground broadcast transmitter space-frequency modulation method having time-domain training sequence |
| CN101431500B (en) * | 2008-10-27 | 2011-04-27 | 宁波大学 | Modulation method for anti-fading digital television ground broadcasting transmitter |
| CN101253721B (en) * | 2005-05-04 | 2011-10-05 | 诺基亚西门子通信有限责任两合公司 | Method for encoding data blocks |
| CN1913396B (en) * | 2006-09-12 | 2011-10-05 | 北京邮电大学 | Single/multiple carrier compatible digital broadcast system communication method |
| CN101237277B (en) * | 2007-01-30 | 2011-10-19 | 展讯通信（上海）有限公司 | Telecast system realization method based on TD-SCDMA |
| CN111371531A (en) * | 2020-02-19 | 2020-07-03 | 哈尔滨工业大学 | Time domain energy interleaving transmission method based on extended weighted fractional Fourier transform |
| CN115001927A (en) * | 2022-07-12 | 2022-09-02 | 深圳智微信通技术有限公司 | Low-voltage power line carrier communication noise suppression method |
-
2003
- 2003-05-19 CN CN 03117885 patent/CN1274150C/en not_active Expired - Fee Related
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100446559C (en) * | 2004-12-30 | 2008-12-24 | 电子科技大学 | Framing method of isomorphic data in two domains in use for ground digital TV transmission system |
| CN101253721B (en) * | 2005-05-04 | 2011-10-05 | 诺基亚西门子通信有限责任两合公司 | Method for encoding data blocks |
| CN1913396B (en) * | 2006-09-12 | 2011-10-05 | 北京邮电大学 | Single/multiple carrier compatible digital broadcast system communication method |
| CN101237277B (en) * | 2007-01-30 | 2011-10-19 | 展讯通信（上海）有限公司 | Telecast system realization method based on TD-SCDMA |
| CN101383803B (en) * | 2008-10-27 | 2010-10-27 | 宁波大学 | Digital television ground broadcast transmitter space-frequency modulation method based on embedded training sequence |
| CN101383805B (en) * | 2008-10-27 | 2010-12-01 | 宁波大学 | Digital television ground broadcast transmitter modulation method having time-domain training sequence |
| CN101383806B (en) * | 2008-10-27 | 2010-12-22 | 宁波大学 | Digital television ground broadcast transmitter space-frequency modulation method having time-domain training sequence |
| CN101431500B (en) * | 2008-10-27 | 2011-04-27 | 宁波大学 | Modulation method for anti-fading digital television ground broadcasting transmitter |
| CN111371531A (en) * | 2020-02-19 | 2020-07-03 | 哈尔滨工业大学 | Time domain energy interleaving transmission method based on extended weighted fractional Fourier transform |
| CN111371531B (en) * | 2020-02-19 | 2022-09-30 | 哈尔滨工业大学 | Time domain energy interleaving transmission method based on extended weighted fractional Fourier transform |
| CN115001927A (en) * | 2022-07-12 | 2022-09-02 | 深圳智微信通技术有限公司 | Low-voltage power line carrier communication noise suppression method |
| CN115001927B (en) * | 2022-07-12 | 2023-10-20 | 深圳智微信通技术有限公司 | Noise suppression method for carrier communication of voltage power line |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1274150C (en) | 2006-09-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1863181A (en) | Method and system for multiplexing data and control information in wireless communication systems | |
| CN1547818A (en) | Wireless transmitter, wireless receiver, and method thereof | |
| CN101124795A (en) | Constrained hopping in wireless communication systems | |
| GB2484153A (en) | Frame preamble with additional signalling capacity for a digital broadcasting system | |
| CN101057472A (en) | Method and apparatus for arranging pilot tones in a mobile communication system | |
| CN1274150C (en) | Simultaneous multi-carrier wave spread spectrum digital TV transmission system with minimum peak-level ratio | |
| CN101056151A (en) | Multi-cast and unicast compatible orthogonal frequency division and time division multiplexing transmission, receiving machine and its method | |
| CN101056133A (en) | Multi-antenna transmission diversity method and device of orthogonal frequency division multiplexing system | |
| CN101057474A (en) | Apparatus and method for processing a digital signal in mobile communication system using orthogonal frequency division multiplexing access | |
| Pepe et al. | 60-GHz transceivers for wireless HD uncompressed video communication in nano-era CMOS technology | |
| CN1798337A (en) | Framing method of isomorphic data in two domains in use for ground digital TV transmission system | |
| CN1209920C (en) | Synchronous multicarrier spread spectrum surface digital TV transmission system | |
| CN1251496C (en) | Multi-carrier transmitting system and method with frequeney-domain pilot signal and hidden pilot signal | |
| KR20040035288A (en) | Multi-carrier transmission system capable of improving the performance of receiving and a method proessing signal thereof | |
| CN1210900C (en) | Method for suppressing phase noise by transmission parameter signallings | |
| CN108462559A (en) | The method that out-of-band radiation is reduced based on IA-PFT in GFDM systems | |
| CN1852275A (en) | Channel correcting method and system | |
| Thenmozhi et al. | Suitability of coded orthogonal frequency division multiplexing (cofdm) for multimedia data transmission in wireless telemedicine applications | |
| CN102281244B (en) | Anti-interference wireless digital broadcast signal transmission method for single frequency network | |
| CN102255850B (en) | Wireless multimedia broadcast signal framing modulation method for single frequency network | |
| CN102263738B (en) | Anti-interference transmission method for digital broadcast wireless signal | |
| CN102263733B (en) | Anti-interference wireless signal transmission method for digital broadcast single-frequency network | |
| CN102263748B (en) | Anti-interference mobile digital broadcast signal transmission method for single-frequency network | |
| CN102281242B (en) | Wireless digital broadcast signal transmission method for single frequency network | |
| CN102263735B (en) | Method for transmitting wireless signals in digital broadcasting single frequency network |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20060906 |