CN101247204B - Robustness pattern detection implementing method of global digital broadcasting system - Google Patents

Abstract

Robustness mode testing method of global digit broadcasting system belongs to robustness mode testing technology field, its character is that: first, four modes execute recursion by method of linearity weighting related delivery, calculating each corresponding correlative value sequence, second method is that correlative value of various mode is multiplied by different sizes constant, global maximum value appears in correlative value sequence of matching mode by the method, finally, current robustness mode is determined according to global maximum value in correlative value sequence. The project is simple visual, can reduce compute complexity degree, judging right ratio is very high by just regulate four constants even if signal-noise ratio is deteriorated greatly, and judging reason of mode testing is very simple.

Description

Robustness pattern in the global digital broadcasting system detects implementation method

Technical field

The present invention relates to the specific implementation that robustness pattern detects in a kind of global digital broadcasting (DRM) system, adopt this method, not only have the characteristics that operand is little, computation complexity is low, hardware spending is little, also has mode adjudging according to simple, intuitive, the high advantage of detection accuracy, under the situation that signal to noise ratio (snr) extremely worsens, still can utilize this method correctly to carry out robustness pattern detects, have very high robustness and flexibility, belong to the reception technique field of radio communication.

Background technology

DRM (Digital Radio Mondiale) is the global digital broadcasting standard, and it is applicable to that frequency comprises the digital am broadcasting of shortwave, medium wave and long wave below 30Mhz.In April calendar year 2001, the system recommendations that DRM alliance proposes pass as formal recommendation in International Telecommunication Union; October calendar year 2001 by european telecommunications standards institute (ETSI) standardization; And pass through through International Power association (IEC) in March, 2002, the DRM system specifications is formally effective, for road has been paved in the digitlization of amplitude modulation broadcasting.It is in service that the part transmitting station of many in the world broadcasting organizations formally drops into commercial broadcasting since in June, 2003 in the DRM mode.

The DRM system adopts OFDM (OFDM) modulation system, after data process quadrature amplitude modulation waiting for transmission (QAM) modulation, be mapped on the different sub carrier together with pilot frequency information, utilize anti-discrete Fourier transform (DFT) (IDFT) to finish the OFDM modulation then, frequency-region signal is transformed into time domain.In order to prevent that intersymbol interference and assurance from still can guarantee the orthogonality of subcarrier when code element is windowed the position inaccuracy, having introduced protection in time domain is cyclic prefix CP at interval.Cyclic prefix CP is to duplicate long L the point in useful data part back of N point to obtain, and adds it starting position of this useful data part to.Like this, the useful data part that CP that L is ordered and N are ordered has been formed a complete OFDM time domain code element jointly, and the overall length of time domain code element is N+L.At last the time domain baseband signal that obtains is gone out through the radio-frequency carrier modulate emission.

The DRM system the maximum data transmission efficiency and the accurate reliability of transmission has defined A, B, four kinds of robustness patterns of C, D in order to realize under different channel conditions.In the DRM standard, provided the robustness pattern that suggestion is used under the different channels condition, as shown in table 1:

The representative condition that each robustness pattern of table 1 is used

Robustness pattern	The representative channel transmission conditions
		A	Gaussian channel has less decline
B	The Time And Frequency selective channel has than long delay and transmits
		C	Same B, but higher Doppler's diffusion is arranged
D	Same B, but serious time-delay and Doppler's diffusion are arranged

Every kind of robustness pattern has defined relevant parameter separately, the duration of the code element number that contains such as each transmission frame, the duration of CP, useful data part, subcarrier spacing or the like.The selection of robustness pattern is in order to resist multipath delay diffusion and the Doppler frequency shift that wireless transmission channel is introduced better.If the recipient correctly realize signal synchronously, Base-Band Processing processes such as equilibrium, demodulation, must know and the parameter of DRM signal correction, so must at first judge robustness pattern.This shows that the robustness pattern in the DRM system detects has consequence, direct relation the extraction to the DRM signal parameter, is the prerequisite that receives the correct work of function.

Also define 6 kinds of frequency bands in the DRM system and taken pattern, be respectively 4.5Khz, 5Khz, 9Khz, 10Khz, 18Khz, 20Khz.When with a certain clock sampling, the duration of useful data part and CP can be separately converted to sampled point number N and L.Distinguish every kind of N, L value under the robustness pattern with subscript, then the useful data partial-length of A, B, C, four kinds of pattern correspondences of D is respectively Na, Nb, Nc, Nd, and corresponding CP length is respectively La, Lb, Lc, Ld.

In the DRM system robustness mode detection method that adopts, basic thought all is N, the L parameter of each robustness pattern of traversal, calculates corresponding sequence of correlation values, comes decision pattern by the periodicity that detects sequence more at present.Wherein, one of algorithm of core is the correlation value calculation of two data segments, and these two data segments are meant respectively from the L long data of certain some beginning and the L long data that begins of N point at interval with it.In the algorithm that calculates correlation, there are four kinds of typical methods at present: the one, maximum likelihood function method, the shortcoming of this method are the computation complexity height, not only relate to relevant delivery, but also relate to two data segment energy calculation; The 2nd, to be correlated with and to get the real part method, the shortcoming of this method is to eliminate the influence of fractional part of frequency offset to correlation computations, can only be used for the very little situation of fractional part of frequency offset, has certain limitation; The 3rd, the sign bit at peek strong point calculates relevant, promptly it is quantified as 1+j according to data point quadrant of living in,-1+j,-1-j makees relevant delivery again behind the 1-j, though this method has kept the replicated relation of duplicating of L point of CP and useful data part back, and computing is simple and convenient, if but the amplitude of signal itself is excessive, only get the amplitude information of sign bit with lossing signal, influential to the accuracy of correlation computations; The 4th, consider intersymbol interference and the exponential weighting correlation method that adopts, though this method has good modeling to approach characteristic to intersymbol interference, be that the suffered intersymbol interference influence of point after leaning on more among the CP is more little, weight coefficient is tending towards 1 more, but because the generation of weight coefficient is by exponential function, so computation complexity height, the weight coefficient required precision height of trying to achieve, generation and storage to weight coefficient under word length limited hardware condition have loss of significance.

One of method of the DRM system robustness mode detection that adopts is at present: N, the L parameter of four kinds of robustness patterns of traversal, utilize the maximum likelihood function method to each the data point calculation correlation in the digital baseband signal of certain-length, obtain four groups of sequence of correlation values, select correlation peak to be the result of the situation of period profile as mode detection.There is following significant disadvantages in this method: the one, computation complexity from, maximum likelihood function not only needs to ask relevant, also needs to find the solution energy; The 2nd, because the CP of robustness pattern A is too short, its peak value is not obvious, and the periodicity between the peak value is not more known where to begin, and therefore the detection of A pattern is usually failed; The 3rd, loaded down with trivial details to the testing process of peak period, the pseudo-peak value that may occur can influence the detection to the cycle.

Two of the method for the DRM system robustness mode detection that adopts are at present: still similar with method one, determine the robustness pattern that mates by the periodicity that detects the correlation peak that maximum likelihood method tries to achieve, difference is that method two only travels through B, C, D pattern, find the solution three groups of corresponding sequence of correlation values, if there is not the periodicity of correlation peak, think that then present mode of operation is A.Though this method accuracy improves greatly, but the shortcoming that still has computation complexity height, cycle detection complexity, and because this round-about way of exclusive method has been adopted in the judgement of robustness pattern A, direct inadequately, efficiency of algorithm is not high, and if current frequency do not have signal owing to can not be judged as B, C, D pattern, to misjudge to being at present and robustness pattern be detected the A pattern have certain limitation.

Summary of the invention

In order to solve the defective that existing DRM system robustness mode detection method can't accurately identify the A pattern, and overcome related operation complexity height, the exponential weighting coefficient realizes that difficulty and mode adjudging are the loaded down with trivial details of foundation with the cycle detection, the present invention proposes the implementation method that robustness pattern detects in a kind of new DRM system, the N of four kinds of robustness patterns of traversal, the L parameter, the form of calculation of the relevant delivery of employing linear weighted function is found the solution sequence of correlation values separately, again these four groups of sequence of correlation values are multiplied by different constants, so that global maximum appears in the sequence of correlation values of match pattern, overall peak-peak in four groups of sequence of correlation values of final search is determined current robustness pattern with this.The robustness pattern that the present invention proposes detects implementation method, and not only correlation computations is simple, computation complexity is low, hardware spending is little, and to adopt global maximum during judgment model be very simple, intuitive of foundation.Use this implementation method, not only reduced the complexity of correlation computations in the present institute employing method, and the judgement foundation when having simplified robustness pattern greatly and detecting, the accuracy that robustness pattern detects is very high, under the situation that signal to noise ratio significantly worsens, if correct selection and the constant that sequence of correlation values multiplies each other still can accurately be judged current robustness pattern.Therefore, robustness pattern detection implementation method has the strong obvious advantage of simple, accurate, flexible and anti-signal to noise ratio decline ability in the DRM system of the present invention's proposition.

The invention is characterized in that described method contains following steps successively:

Step (1) is modulated the traversal that the digital baseband signal that obtains carries out four kinds of patterns to handle, separate IQ through radio-frequency front-end, and the steps in sequence when at every turn traveling through is as follows:

Step (1.1) is chosen useful data partial-length N and CP length L corresponding under this traversal mode;

Step (1.2) is got and is separated the digital baseband signal data that obtain after the IQ modulation, and the time-domain position sequence number of order data point correspondence wherein is θ, obtains its pairing correlation according to following formula:

$\mathrm{Cor}\left(\mathrm{\θ}\right)=|\underset{k=\mathrm{\θ}}{\overset{\mathrm{\θ}+L-1}{\mathrm{\Σ}}}\mathrm{weight}(\mathrm{mode},k-\mathrm{\θ})\·[r\left(k\right)r^{*}(k+N)\left]\right|$

Wherein, r (k) k data of DRM baseband signal, r for receiving ^*(k) represent conjugate operation, weight (mode, k-θ) is a weighting function, is the function of mode of operation and k, and its expression formula is:

$\mathrm{weight}(\mathrm{mode},n)=\left\{\begin{array}{cc}{2}^{-6}n+(1-2^{-5}{L}_{\mathrm{mode}}),& 0\&le;n<\frac{L_{\mathrm{mode}}}{2},n\&Element;Z\\ 1,& \frac{L_{\mathrm{mode}}}{2}\&le;n<L_{\mathrm{mode}},n\&Element;Z\end{array}\right.$

L _ModeBe La, Lb, Lc, Ld, represent the CP length under A, B, C, the D pattern respectively.

The size of weight coefficient, with the distribution of intersymbol interference (ISI) interfering energy relevant, embodied data point and the corresponding with it correlation power that is replicated between the data point among the CP.Because to be subjected to the big more ISI of the being interfering energy of ISI influence that previous code element brings big more for forward more point among the CP, therefore and the correlation that is replicated between the data point weak more, corresponding weight coefficient is more little.The weighting function that the present invention adopts has been simplified the weighting function of exponential type, and it has been done linearization process.Under each robustness pattern, the corresponding linear increasing function that is distributed in 0 to 1 scope of CP first half, the index power with 2 are that slope is to calculate, reduce hardware spending for convenience; The weight coefficient of CP latter half correspondence is 1, this is not only because the ISI influence that the point of CP after leaning on more is subjected to is more little, also be because the ISI interfering energy mainly concentrates on the first half of CP, to such an extent as to and do not consider interior simultaneously in very little can the ignoring of energy of CP latter half.

Step (2) is multiplied by four constants respectively with four groups of sequence of correlation values that obtain during each robustness pattern of traversal in the step (1).If the constant of D pattern correspondence is 1, so the constant of A pattern correspondence can be in 1.6 to 2.6 scopes value, the constant of B pattern correspondence can be in 0.9 to 1.7 scope value, the constant of C pattern correspondence can be in 0.9 to 1.7 scope value.Why will be multiplied by 4 constants, be for global maximum necessarily being appeared in the pattern that is complementary, being convenient to step (3) and coming decision pattern by the search global maximum.If current demand signal is the A pattern, because the CP of A mode signal is very short, make that the correlation peak that obtains with A pattern N, L calculation of parameter is not obvious, differ very little with the maximum under other mode computation, global maximum not necessarily appears in the sequence of correlation values of A pattern, therefore the correlation of A pattern need be enlarged certain multiple so that it tangible global maximum occurs; And if current demand signal is B, C or D pattern, be complementary N, the L parameter of pattern of use can both obtain very significantly peak value, and there is certain redundancy in the amplitude of global maximum, just getting it right its decay certain multiple can be not influential yet, but the size after the decay can not be lower than the size after A pattern correlation enlarges, so have certain restricting relation between four constants.

The maximum in four groups of sequence of correlation values that obtain is handled in step (3) search through step (2), therefrom select global maximum, and the pattern at this global maximum place is a court verdict, and so far robustness pattern detects and finishes.

Robustness pattern in the DRM system that the present invention proposes detects implementation method, its advantage comprises that mainly the introducing of linear weighted function coefficient can offset the influence of part intersymbol interference, not only pseudo-peak value there is inhibitory action, and computation complexity is compared the exponential weighting form and has been descended a lot, hardware spending is little, be beneficial to the realization of hardware, under the hardware word size condition of limited, can accurately store weight coefficient; In addition, foundation to mode adjudging no longer adopts loaded down with trivial details cycle detection method, but search for global maximum by the size of adjusting sequence of correlation values, carrying out robustness pattern by this physical quantity simply and intuitively of global maximum detects, not only accuracy is high, and under the situation that signal to noise ratio descends, by optimizing and revising the constant of amplitude, still can correctly search out global maximum and appear in the pattern that is complementary, to reach the purpose of correct detection present mode.Therefore the method that proposes of the present invention accuracy height not only, and the ability that anti-signal to noise ratio descends is strong, even reduces to when very low when signal to noise ratio, can be used for adjusting the constant of sequence of correlation values amplitude by optimization, correctly finish detection, have very high flexibility robustness pattern.

Description of drawings

Fig. 1 is that the robustness pattern in the DRM system detects the circuit theory module that implementation method relates to.

Fig. 2 is the flow chart that the robustness pattern in the DRM system detects implementation method.

Embodiment

Robustness pattern in the DRM system that the present invention proposes detects implementation method, and its pairing circuit theory module is made up of memory, correlator, multiplier, four parts of comparator:

1) memory is used for storing digital baseband signal, carries out follow-up robustness pattern by these data and detects processing;

2) correlator calculates the corresponding correlation of each point when four kinds of robustness patterns of traversal, can obtain the sequence of correlation values of each robustness pattern correspondence like this.Correlator adopts following formula to calculate the correlation of each point:

$\mathrm{Cor}\left(\mathrm{\&theta;}\right)=|\underset{k=\mathrm{\&theta;}}{\overset{\mathrm{\&theta;}+L-1}{\mathrm{\&Sigma;}}}\mathrm{weight}(\mathrm{mode},k-\mathrm{\&theta;})\&CenterDot;[r\left(k\right)r^{*}(k+N)\left]\right|$

Wherein, N and L are respectively pairing useful data partial-length of the robustness pattern of current traversal and CP length, weight (mode, k-θ) is the pairing weighting function of robustness pattern of current traversal, θ is the time-domain position sequence number of this data point, r (k) k data of DRM baseband signal for receiving, r ^*(k) represent conjugate operation.Two parts data of in correlator, making related operation be respectively L data beginning from this data point and with this data point N L data that data point begins at interval backward.The employing linear weighted function is handled each product term in the related operation, and purpose is the intersymbol interference of offsetting a part, suppresses the generation of pseudo-peak value, simplifies the computational complexity of exponential weighting form simultaneously; The as a result delivery relevant to linear weighted function, the influence that can remove fractional part of frequency offset;

3) four groups of sequence of correlation values difference quadruplication definite constants that utilize multiplier that traversal is obtained, so that its amplitude size is adjusted, make correctly to detect global maximum B, C, D pattern clearly, can correctly detect the unconspicuous A pattern of peak value simultaneously because CP length is too short;

4) search for global maximum in adjusted four groups of sequence of correlation values by comparator, the pattern of this global maximum correspondence is the result that robustness pattern detects.

Above-mentioned traversal is asked in the relevant process, and definite method of linear weighted function coefficient is:

$\mathrm{weight}(\mathrm{mode},n)=\left\{\begin{array}{cc}{2}^{-6}n+(1-2^{-5}{L}_{\mathrm{mode}}),& 0\&le;n<\frac{L_{\mathrm{mode}}}{2},n\&Element;Z\\ 1,& \frac{L_{\mathrm{mode}}}{2}\&le;n<L_{\mathrm{mode}},n\&Element;Z\end{array}\right.$

L wherein _ModeBe La, Lb, Lc, Ld, represent the CP length of A, B, C, D pattern respectively.

Hold in both hands under the sexual norm in each Shandong, weight coefficient is a linear increasing function that is distributed in 0 to 1 scope at the CP first half, and the index power with 2 is that slope is to calculate, reduce hardware spending for convenience; At the CP latter half is 1, and this is not only because the ISI influence that the point of CP after leaning on more is subjected to is more little, also is because the ISI interfering energy mainly concentrates on the first half of CP, to such an extent as to and do not consider interior in very little can the ignoring of energy of CP latter half simultaneously.

In the process of above-mentioned adjustment sequence of correlation values, the pairing constant of each robustness pattern determines that method is:

The robustness pattern detection method failure reasons that adopts is because the CP length of A pattern is too short at present, makes that peak value and periodicity thereof are not obvious, thereby has caused the erroneous judgement to the A pattern.Therefore, the robustness pattern that proposes among the present invention detects implementation method at this problem, changes the mode adjudging foundation, comes detecting pattern by the search global maximum.Be multiplied by four definite constants respectively to traveling through relevant four groups of sequence of correlation values of trying to achieve,, be convenient to the detection of pattern so that global maximum necessarily appears in the pattern that is complementary.If current demand signal is the A pattern, because the CP of A mode signal is very short, make that the correlation peak that obtains with A pattern N, L calculation of parameter is not obvious, differ very little with the maximum under other mode computation, global maximum not necessarily appears in the sequence of correlation values of A pattern, therefore the correlation of A pattern need be enlarged certain multiple so that it tangible global maximum occurs; And if current demand signal is B, C or D pattern, use N, the L parameter of match pattern can both obtain very significantly peak value, and there is certain redundancy in the amplitude of global maximum, just getting it right its decay certain multiple can be not influential yet, but the size after the decay can not be lower than the size after A pattern correlation enlarges, so have certain restricting relation between four constants.

Below in conjunction with accompanying drawing, describe content of the present invention in detail:

Fig. 1 is that the robustness pattern in the DRM system detects the circuit theory module that implementation method relates to.As shown in Figure 1, the realization of robustness pattern detection is followed after radio-frequency front-end is handled reconciliation IQ modulation module.At first store the digital baseband signal that the IQ modulation obtains of separating of certain-length,, carry out follow-up robustness pattern with these data and detect processing as the baseband signal of 5 A pattern Baud Lengths.Travel through N, the L parameter of various robustness patterns then, when getting surely a kind of robustness pattern, select the N and the L value of this pattern correspondence, the relevant delivery expression formula of linear weighted function that the data point of storage is utilized this method successively and adopted is calculated its corresponding correlation by correlator, can obtain four groups of sequence of correlation values of corresponding four kinds of robustness patterns like this.In order correctly to identify the very short A pattern of CP, do not influence simultaneously judgement situation again to other patterns, introduced and be respectively applied for four constants adjusting four groups of sequence of correlation values, utilize multiplier that constant is taken on the corresponding sequence of correlation values, the comparator after being convenient to can correctly search out global maximum.Search for global maximum in the sequence of correlation values of multiplier output by comparator at last.No matter under which kind of robustness pattern, the global maximum that searches out necessarily appears in the pattern that is complementary, and has correctly finished the detection of robustness pattern.

Fig. 2 is the flow chart that the robustness pattern in the DRM system detects implementation method.As shown in Figure 2, the detailed process of robustness pattern detection implementation method is in the DRM system of the present invention's proposition:

1) from conciliate the digital baseband signal that the IQ modulation treatment obtains through the receiver radio frequency front end, reads in the data of certain-length,, leave in the memory and detect used for robustness pattern as the i.e. individual data point of 5 (Na+La) of 5 A pattern Baud Lengths;

2) get the useful data partial-length Na and the CP length L a of A pattern correspondence, to data point such as the individual data point of preceding 5 (Na+La)-(Na+La) that leaves the previous section in the memory in, calculate the value of the relevant delivery of linear weighted function successively by correlator, used formula is:

$\mathrm{Cor}\left(\mathrm{\&theta;}\right)=|\underset{k=\mathrm{\&theta;}}{\overset{\mathrm{\&theta;}+L-1}{\mathrm{\&Sigma;}}}\mathrm{weight}(\mathrm{mode},k-\mathrm{\&theta;})\&CenterDot;[r\left(k\right)r^{*}(k+N)\left]\right|$

Wherein, N=Na, L=La, θ are the time-domain position sequence number of this data point,

Weight coefficient $\mathrm{weight}(\mathrm{mode},n)=\left\{\begin{array}{cc}{2}^{-6}n+(1-2^{-5}{L}_{\mathrm{mode}}),& 0\&le;n<\frac{L_{\mathrm{mode}}}{2},n\&Element;Z\\ 1,& \frac{L_{\mathrm{mode}}}{2}\&le;n<L_{\mathrm{mode}},n\&Element;Z\end{array}\right.$

To try to achieve one group of sequence of correlation values like this corresponding to the A pattern;

3) get the useful data partial-length Nb and the CP length L b of B pattern correspondence, to data point such as the individual data point of preceding 5 (Na+La)-(Nb+Lb) that leaves the previous section in the memory in, calculate the value of the relevant delivery of linear weighted function successively by correlator, used formula is:

$\mathrm{Cor}\left(\mathrm{\&theta;}\right)=|\underset{k=\mathrm{\&theta;}}{\overset{\mathrm{\&theta;}+L-1}{\mathrm{\&Sigma;}}}\mathrm{weight}(\mathrm{mode},k-\mathrm{\&theta;})\&CenterDot;[r\left(k\right)r^{*}(k+N)\left]\right|$

Wherein, N=Nb, L=Lb, θ are the time-domain position sequence number of this data point,

Weight coefficient $\mathrm{weight}(\mathrm{mode},n)=\left\{\begin{array}{cc}{2}^{-6}n+(1-2^{-5}{L}_{\mathrm{mode}}),& 0\&le;n<\frac{L_{\mathrm{mode}}}{2},n\&Element;Z\\ 1,& \frac{L_{\mathrm{mode}}}{2}\&le;n<L_{\mathrm{mode}},n\&Element;Z\end{array}\right.$

To try to achieve one group of sequence of correlation values like this corresponding to the B pattern;

4) get the useful data partial-length Nc and the CP length L c of C pattern correspondence, to data point such as the individual data point of preceding 5 (Na+La)-(Nc+Lc) that leaves the previous section in the memory in, calculate the value of the relevant delivery of linear weighted function successively by correlator, used formula is:

$\mathrm{Cor}\left(\mathrm{\&theta;}\right)=|\underset{k=\mathrm{\&theta;}}{\overset{\mathrm{\&theta;}+L-1}{\mathrm{\&Sigma;}}}\mathrm{weight}(\mathrm{mode},k-\mathrm{\&theta;})\&CenterDot;[r\left(k\right)r^{*}(k+N)\left]\right|$

Wherein, N=Nc, L=Lc, θ are the time-domain position sequence number of this data point,

Weight coefficient $\mathrm{weight}(\mathrm{mode},n)=\left\{\begin{array}{cc}{2}^{-6}n+(1-2^{-5}{L}_{\mathrm{mode}}),& 0\&le;n<\frac{L_{\mathrm{mode}}}{2},n\&Element;Z\\ 1,& \frac{L_{\mathrm{mode}}}{2}\&le;n<L_{\mathrm{mode}},n\&Element;Z\end{array}\right.$

To try to achieve one group of sequence of correlation values like this corresponding to the C pattern;

5) get the useful data partial-length Nd and the CP length L d of D pattern correspondence, to data point such as the individual data point of preceding 5 (Na+La)-(Nd+Ld) that leaves the previous section in the memory in, calculate the value of the relevant delivery of linear weighted function successively by correlator, used formula is:

$\mathrm{Cor}\left(\mathrm{\&theta;}\right)=|\underset{k=\mathrm{\&theta;}}{\overset{\mathrm{\&theta;}+L-1}{\mathrm{\&Sigma;}}}\mathrm{weight}(\mathrm{mode},k-\mathrm{\&theta;})\&CenterDot;[r\left(k\right)r^{*}(k+N)\left]\right|$

Wherein, N=Nd, L=La, θ are the time-domain position sequence number of this data point,

Weight coefficient $\mathrm{weight}(\mathrm{mode},n)=\left\{\begin{array}{cc}{2}^{-6}n+(1-2^{-5}{L}_{\mathrm{mode}}),& 0\&le;n<\frac{L_{\mathrm{mode}}}{2},n\&Element;Z\\ 1,& \frac{L_{\mathrm{mode}}}{2}\&le;n<L_{\mathrm{mode}},n\&Element;Z\end{array}\right.$

To try to achieve one group of sequence of correlation values like this corresponding to the D pattern;

6) utilize multiplier that the sequence of correlation values under the A pattern is multiplied by a definite constant;

7) utilize multiplier that the sequence of correlation values under the B pattern is multiplied by a definite constant;

8) utilize multiplier that the sequence of correlation values under the C pattern is multiplied by a definite constant;

9) utilize multiplier that the sequence of correlation values under the D pattern is multiplied by a definite constant;

10) search for four groups of global maximums in the sequence of correlation values by comparator;

11) decision pattern is the robustness pattern testing result with the pattern of global maximum correspondence.

Claims (1)

1. the robustness pattern detection method in the global digital broadcasting system is characterized in that, described method realizes in the digital integrated circuit of receiving terminal successively according to the following steps

Step (1) accesses from memory through radio-frequency front-end and handles, separates the digital baseband signal that the IQ modulation obtains, and described digital baseband signal is sent to a correlator carries out A, B, C, the D detection of totally four kinds of robustness patterns, and its step is as follows when detecting at every turn:

Step (1.1) is chosen useful data partial-length N and Cyclic Prefix part length L in the digital baseband signal that correspondence is set under this pattern;

Step (1.2) is got the data q that is positioned at the front preseting length in the digital baseband signal that global digital broadcasting system that separating described in the step (1) obtain after the IQ modulation uses, wherein the length of q is useful data partial-length and the Cyclic Prefix part length sum that the integral multiple of A pattern Baud Length deducts the robustness pattern correspondence that is traveling through again, make wherein the time-domain position sequence number of data point correspondence is θ, obtain the value Cor (θ) of the relevant delivery of the pairing linear weighted function of data q described in this step (1.2) as follows

$\mathrm{Cor}\left(\mathrm{\&theta;}\right)=|\underset{k=\mathrm{\&theta;}}{\overset{\mathrm{\&theta;}+L-1}{\mathrm{\&Sigma;}}}\mathrm{weight}(\mathrm{mode},k-\mathrm{\&theta;})\&CenterDot;[r\left(k\right)r^{*}(k+N)\left]\right|,$

Wherein:

Weight (mode, k-θ) is a weighting function, is the function of described robustness pattern and k, represents with following formula:

$\mathrm{weight}(\mathrm{mode},n)=\left\{\begin{array}{cc}{2}^{-6}n+(1-2^{-5}{L}_{\mathrm{mode}})& ,0\&le;n<\frac{L_{\mathrm{mode}}}{2},n\&Element;Z\\ 1& ,\frac{L_{\mathrm{mode}}}{2}\&le;n<L_{\mathrm{mode}},n\&Element;Z\end{array}\right.,$

N is an integer, is limited to 0 under it, and the upper limit depends on the circulating prefix-length L under the current traversal mode _Mode, L _ModeBe La, Lb, Lc, Ld, represent the CP length under A, B, C, the D pattern respectively; R is a received signal; * be the complex conjugate symbol;

Step (2) multiply by the constant of the fixed size of a setting respectively on four groups of sequence of correlation values that step (1.2) traversal obtains with multiplier, wherein the constant of D pattern correspondence is 1, the constant of A pattern correspondence is value in 1.6 to 2.6 scopes, the constant of B pattern correspondence is value in 0.9 to 1.7 scope, the constant of C pattern correspondence is value in 0.9 to 1.7 scope, makes global maximum necessarily appear in the robustness pattern that is complementary;

Step (3) is handled the global maximum in four groups of sequence of correlation values that obtain with a comparator search process step (2), the pairing pattern of this global maximum is the robustness pattern that judgement obtains.

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