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

Robustness pattern detection implementing method of global digital broadcasting system Download PDF

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CN101247204B
CN101247204B CN2007101779997A CN200710177999A CN101247204B CN 101247204 B CN101247204 B CN 101247204B CN 2007101779997 A CN2007101779997 A CN 2007101779997A CN 200710177999 A CN200710177999 A CN 200710177999A CN 101247204 B CN101247204 B CN 101247204B
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徐淑正
曾琳
张鹏
王鹏军
杨华中
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Tsinghua University
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Abstract

全球数字广播系统中的鲁棒性模式检测方法属于鲁棒性模式检测技术领域,其特征在于,首先用线性加权相关取模的方法对四种模式进行遍历,求出各自对应的相关值序列,再用各种模式所得的相关值乘以不同大小的常数的方法以使得全局最大值出现在其匹配模式的相关值序列中,最后根据相关值序列中的全局最大值来确定当前的鲁棒性模式。本方案具有简单直观、可降低计算复杂度、而且即便在信噪比大幅恶化时只需调节四个常数,其判决正确率仍然非常高,并且其模式检测的判决依据也非常简单。

Figure 200710177999

The robustness mode detection method in the global digital broadcasting system belongs to the robustness mode detection technical field, and it is characterized in that, at first four kinds of modes are traversed with the method of linear weighted correlation modulus, and the respective corresponding correlation value sequences are obtained, Then multiply the correlation values obtained by various modes by constants of different sizes so that the global maximum value appears in the correlation value sequence of the matching mode, and finally determine the current robustness according to the global maximum value in the correlation value sequence model. The scheme is simple and intuitive, can reduce the computational complexity, and even if the signal-to-noise ratio is greatly deteriorated, only four constants need to be adjusted, the judgment accuracy rate is still very high, and the judgment basis of the pattern detection is also very simple.

Figure 200710177999

Description

全球数字广播系统中的鲁棒性模式检测实现方法 Robust Pattern Detection Implementation Method in Global Digital Broadcasting System

技术领域technical field

本发明涉及一种全球数字广播(DRM)系统中鲁棒性模式检测的具体实现方案,采用本方法,不仅具有运算量小、计算复杂度低、硬件开销小的特点,还具有模式判决依据简单直观、检测准确性极高的优点,在信噪比(SNR)极度恶化的情况下,仍然能够利用本方法正确进行鲁棒性模式检测,具有很高的鲁棒性和灵活性,属于无线通信的接收技术领域。The present invention relates to a specific implementation scheme of robust mode detection in a global digital broadcasting (DRM) system. By adopting the method, it not only has the characteristics of small amount of calculation, low computational complexity, and small hardware overhead, but also has simple basis for mode judgment. It has the advantages of intuitiveness and high detection accuracy. In the case of extremely deteriorated signal-to-noise ratio (SNR), this method can still be used to perform robust mode detection correctly. It has high robustness and flexibility and belongs to wireless communication receiving technical field.

背景技术Background technique

DRM(Digital Radio Mondiale)是全球数字广播标准,它适用于频率在30Mhz以下包括短波、中波和长波在内的数字调幅广播。2001年4月,DRM联盟提出的系统建议在国际电信联盟(ITU)作为正式建议书而获得通过;在2001年10月被欧洲电信标准化组织(ETSI)标准化;并在2002年3月经国际电工协会(IEC)通过,DRM系统规范正式生效,为调幅广播的数字化铺平了道路。国际上不少广播机构的部分发射台已经从2003年6月开始以DRM方式正式投入商业广播运行中了。DRM (Digital Radio Mondiale) is a global digital broadcasting standard, which applies to digital AM broadcasting with frequencies below 30Mhz, including shortwave, medium wave and long wave. In April 2001, the system proposal proposed by the DRM Alliance was adopted as a formal recommendation by the International Telecommunication Union (ITU); it was standardized by the European Telecommunications Standardization Organization (ETSI) in October 2001; and it was approved by the International Electrotechnical Association in March 2002. (IEC) passed, and the DRM system specification came into effect, paving the way for the digitization of AM broadcasting. Some transmitter stations of many broadcasting organizations in the world have been officially put into commercial broadcast operation in the form of DRM since June 2003.

DRM系统采用正交频分复用(OFDM)调制方式,将待传输的数据经过正交幅度调制(QAM)调制后,和导频信息一起映射到不同子载波上,然后利用反离散傅立叶变换(IDFT)完成OFDM调制,将频域信号转化到时域。为了防止码元串扰和保证当码元开窗位置不精确时仍能保证子载波的正交性,在时域引入了保护间隔即循环前缀CP。循环前缀CP是复制N点长的有用数据部分后L个点得到的,并将其添加到该有用数据部分的开始位置。这样,L点的CP和N点的有用数据部分共同组成了一个完整的OFDM时域码元,时域码元的总体长度为N+L。最后将得到的时域基带信号经射频载波调制发射出去。The DRM system adopts the Orthogonal Frequency Division Multiplexing (OFDM) modulation method. After the data to be transmitted is modulated by the Quadrature Amplitude Modulation (QAM), it is mapped to different subcarriers together with the pilot information, and then uses the inverse discrete Fourier transform ( IDFT) completes OFDM modulation and converts the frequency domain signal to the time domain. In order to prevent symbol crosstalk and ensure the orthogonality of subcarriers when the symbol windowing position is inaccurate, a guard interval, cyclic prefix CP, is introduced in the time domain. The cyclic prefix CP is obtained by copying the N-point long useful data part after L points, and adding it to the beginning position of the useful data part. In this way, the CP of point L and the useful data part of point N together form a complete OFDM time-domain symbol, and the overall length of the time-domain symbol is N+L. Finally, the obtained time-domain baseband signal is transmitted through radio frequency carrier modulation.

DRM系统为了在不同的信道条件下实现最大的数据传输效率和传输的准确可靠性,定义了A、B、C、D四种鲁棒性模式。在DRM标准里,给出了不同信道条件下建议使用的鲁棒性模式,如表1所示:In order to achieve maximum data transmission efficiency and transmission accuracy and reliability under different channel conditions, the DRM system defines four robustness modes A, B, C, and D. In the DRM standard, the recommended robustness modes under different channel conditions are given, as shown in Table 1:

表1各鲁棒性模式应用的典型条件Table 1 Typical conditions for the application of each robustness mode

  鲁棒性模式Robust Mode   典型信道传输条件Typical channel transmission conditions   AA   高斯信道,有较小衰落Gaussian channel with minor fading   BB   时间与频率选择性信道,有较长延时传输Time and frequency selective channel with long delay transmission   CC   同B,但有较高的多普勒扩散Same as B, but with higher Doppler spread   DD   同B,但有严重的延时和多普勒扩散Same as B, but with severe time delay and Doppler spread

每种鲁棒性模式定义了各自的相关参数,比如每个传输帧含有的码元个数、CP的持续时间、有用数据部分的持续时间、子载波间隔等等。鲁棒性模式的选择是为了更好地抵抗无线传输信道引入的多径延时扩散和多普勒频移。如果要在接收方正确实现信号的同步、均衡、解调等基带处理过程,必须要知道与DRM信号相关的参数,因此必须首先判断鲁棒性模式。由此可见,DRM系统中的鲁棒性模式检测具有重要的地位,直接关系着对DRM信号参数的提取,是接收机能正确工作的前提。Each robustness mode defines its own related parameters, such as the number of symbols contained in each transmission frame, the duration of CP, the duration of useful data part, subcarrier spacing, and so on. The choice of the robust mode is to better resist the multipath delay spread and Doppler frequency shift introduced by the wireless transmission channel. If the baseband processing processes such as signal synchronization, equalization, and demodulation are to be correctly implemented at the receiver, the parameters related to the DRM signal must be known, so the robustness mode must be judged first. It can be seen that the robust pattern detection in the DRM system plays an important role, which is directly related to the extraction of the DRM signal parameters and is the prerequisite for the receiver to work correctly.

DRM系统中还定义了6种频带占用模式,分别为4.5Khz、5Khz、9Khz、10Khz、18Khz、20Khz。当以某一时钟采样时,可以将有用数据部分和CP的持续时间分别转化为采样点个数N和L。以下标来区别每种鲁棒性模式下的N、L值,则A、B、C、D四种模式对应的有用数据部分长度分别为Na、Nb、Nc、Nd,对应的CP长度分别为La、Lb、Lc、Ld。The DRM system also defines 6 frequency band occupancy modes, which are 4.5Khz, 5Khz, 9Khz, 10Khz, 18Khz, and 20Khz. When sampling with a certain clock, the useful data part and the duration of the CP can be converted into the numbers N and L of sampling points, respectively. The following subscripts are used to distinguish the N and L values in each robustness mode, then the lengths of the useful data parts corresponding to the four modes A, B, C, and D are Na, Nb, Nc, and Nd respectively, and the corresponding CP lengths are respectively La, Lb, Lc, Ld.

目前采用的DRM系统鲁棒性模式检测方法中,基本思想都是遍历各鲁棒性模式的N、L参数,计算对应的相关值序列,再通过检测序列的周期性来判决模式。其中,核心的算法之一是两个数据段的相关值计算,这两个数据段分别是指从某点开始的L长数据和与之间隔N点开始的L长数据。在计算相关值的算法中,目前存在四种典型方法:一是最大似然函数法,这种方法的缺点是计算复杂度高,不仅涉及到相关取模,而且还涉及到对两个数据段能量的计算;二是相关取实部法,这种方法的缺点是无法消除小数倍频偏对相关计算的影响,只能用于小数倍频偏很小的情况,存在一定的局限性;三是取数据点的符号位计算相关,即根据数据点所处象限将其量化为1+j,-1+j,-1-j,1-j后再做相关取模,这种方法虽然保留了CP与有用数据部分后L个点的复制重复关系,而且运算简单方便,但是如果信号本身的幅度过大,仅仅取符号位将丢失信号的幅度信息,对相关计算的准确性有影响;四是考虑到码间串扰而采用的指数加权相关法,这种方法虽然对码间串扰有很好的建模逼近特性,即CP中越靠后的点所受的码间串扰影响越小、加权系数越趋于1,但是由于加权系数的产生是借助指数函数,因此计算复杂度高,求得的加权系数精度要求高,在字长有限的硬件条件下对加权系数的产生和存储会有精度损失。In the currently used DRM system robust mode detection method, the basic idea is to traverse the N and L parameters of each robust mode, calculate the corresponding correlation value sequence, and then judge the mode by detecting the periodicity of the sequence. Among them, one of the core algorithms is the calculation of the correlation value of two data segments, which respectively refer to the L-long data starting from a certain point and the L-long data starting from an N point in between. In the algorithm for calculating correlation values, there are currently four typical methods: one is the maximum likelihood function method. The disadvantage of this method is that the calculation complexity is high. Calculation of energy; the second is the method of taking the real part of the correlation. The disadvantage of this method is that it cannot eliminate the influence of the fractional frequency offset on the correlation calculation, and it can only be used in the case of a small fractional frequency offset, which has certain limitations. ; The third is to take the sign bit of the data point to calculate the correlation, that is, quantify it to 1+j, -1+j, -1-j, 1-j according to the quadrant where the data point is located, and then do the correlation modulo. Although the duplication and repetition relationship between the CP and the last L points of the useful data part is retained, and the calculation is simple and convenient, if the amplitude of the signal itself is too large, only taking the sign bit will lose the amplitude information of the signal, which will affect the accuracy of the correlation calculation. ; The fourth is the exponential weighted correlation method that takes into account the intersymbol interference. Although this method has a good modeling and approximation characteristic for intersymbol interference, that is, the later points in the CP are less affected by intersymbol interference. The weighting coefficient tends to 1, but because the weighting coefficient is generated by means of an exponential function, the calculation complexity is high, and the obtained weighting coefficient requires high precision. Under the hardware condition of limited word length, the generation and storage of the weighting coefficient will be difficult. loss of precision.

目前采用的DRM系统鲁棒性模式检测的方法之一是:遍历四种鲁棒性模式的N、L参数,利用最大似然函数法对一定长度的数字基带信号中的每个数据点计算相关值,得到四组相关值序列,选择相关峰值呈周期分布的情况作为模式检测的结果。这种方法存在以下明显的缺点:一是计算复杂度离,最大似然函数不仅需要求相关,还需要求解能量;二是由于鲁棒性模式A的CP过短,其峰值不明显,峰值之间的周期性更无从谈起,因此对A模式的检测常常失败;三是对峰值周期性的检测过程繁琐,可能出现的伪峰值会影响对周期的检测。One of the methods currently used for DRM system robustness mode detection is: traverse the N and L parameters of the four robustness modes, and use the maximum likelihood function method to calculate the correlation of each data point in the digital baseband signal of a certain length. Values, four sets of correlation value sequences are obtained, and the case where the correlation peaks are periodically distributed is selected as the result of pattern detection. This method has the following obvious shortcomings: First, the computational complexity is far from the maximum likelihood function, which not only needs to find the correlation, but also needs to solve the energy; second, because the CP of the robust mode A is too short, its peak value is not obvious, and the peak value There is no way to talk about the periodicity between them, so the detection of A mode often fails; the third is that the detection process of the peak periodicity is cumbersome, and the possible false peaks will affect the detection of the period.

目前采用的DRM系统鲁棒性模式检测的方法之二是:仍然和方法一类似,通过检测最大似然法求得的相关峰值的周期性来确定匹配的鲁棒性模式,不同点在于方法二只对B、C、D模式进行遍历,求解对应的三组相关值序列,如果都不存在相关峰值的周期性,则认为目前的工作模式是A。这种方法虽然正确率大大提高,但是仍然具有计算复杂度高、周期检测复杂的缺点,而且由于对鲁棒性模式A的判断采用了排除法这种间接的方法,不够直接,算法效率不高,并且如果当前频点没有信号,由于不能判断为B、C、D模式,将错判为目前为A模式,使鲁棒性模式检测存在一定的局限性。The second method of DRM system robustness mode detection currently used is: still similar to method one, the matching robustness mode is determined by detecting the periodicity of the correlation peak obtained by the maximum likelihood method, the difference lies in method two Only traverse B, C, and D modes, and solve the corresponding three sets of correlation value sequences. If there is no periodicity of correlation peaks, the current working mode is considered to be A. Although the accuracy rate of this method is greatly improved, it still has the disadvantages of high computational complexity and complex cycle detection, and because the indirect method of elimination is used to judge the robustness mode A, it is not direct enough and the algorithm efficiency is not high , and if there is no signal at the current frequency point, because it cannot be judged as B, C, or D mode, it will be wrongly judged as the current A mode, so that there are certain limitations in robust mode detection.

发明内容Contents of the invention

为了解决现有DRM系统鲁棒性模式检测方法无法准确识别出A模式的缺陷,以及克服相关运算复杂度高、指数加权系数实现困难以及模式判决以周期检测为依据的繁琐,本发明提出了一种新的DRM系统中鲁棒性模式检测的实现方法,遍历四种鲁棒性模式的N、L参数,采用线性加权相关取模的计算形式求解各自的相关值序列,再对这四组相关值序列乘上不同的常数,以使得全局最大值出现在匹配模式的相关值序列中,最后搜索四组相关值序列中的全局最大峰值,以此来确定当前的鲁棒性模式。本发明提出的鲁棒性模式检测实现方法不仅相关计算简单、计算复杂度低、硬件开销小,而且判断模式时采用全局最大值为依据非常简单直观。使用该实现方法,不仅降低了目前所采用方法中相关计算的复杂度,而且大大简化了鲁棒性模式检测时的判决依据,鲁棒性模式检测的正确率非常高,在信噪比大幅恶化的情况下,如果正确选择与相关值序列相乘的常数,仍然能够准确判断出当前鲁棒性模式。因此,本发明提出的DRM系统中鲁棒性模式检测实现方法具有简单、准确、灵活和抗信噪比下降能力强的明显优点。In order to solve the defect that the existing DRM system robust mode detection method cannot accurately identify the A mode, and overcome the high complexity of related calculations, the difficulty in realizing the exponential weighting coefficient, and the cumbersomeness of mode judgment based on periodic detection, the present invention proposes a A new implementation method of robust pattern detection in the DRM system, traversing the N and L parameters of four robust patterns, adopting the calculation form of linear weighted correlation modulo to solve the respective correlation value sequences, and then the four groups of correlation The value sequence is multiplied by different constants so that the global maximum appears in the correlation value sequence of the matching pattern, and finally the global maximum peak in the four sets of correlation value sequences is searched to determine the current robustness mode. The implementation method of robust mode detection proposed by the invention not only has simple correlation calculation, low calculation complexity and small hardware overhead, but also uses the global maximum value as the basis for judging the mode is very simple and intuitive. Using this implementation method not only reduces the complexity of correlation calculations in the currently used methods, but also greatly simplifies the decision basis for robust pattern detection. The accuracy of robust pattern detection is very high, and the signal-to-noise ratio deteriorates significantly. In the case of , if the constant to be multiplied with the correlation value sequence is correctly selected, the current robustness mode can still be accurately judged. Therefore, the implementation method of robust pattern detection in the DRM system proposed by the present invention has the obvious advantages of simplicity, accuracy, flexibility and strong ability to resist the decline of signal-to-noise ratio.

本发明的特征在于,所述方法依次含有以下步骤:The present invention is characterized in that the method comprises the following steps in sequence:

步骤(1)对经过射频前端处理、解IQ调制得到的数字基带信号进行四种模式的遍历,每次遍历时的步骤依次如下:Step (1) carries out the traversal of four modes to the digital baseband signal obtained through radio frequency front-end processing and de-IQ modulation, and the steps during each traversal are as follows:

步骤(1.1)选取该遍历模式下对应的有用数据部分长度N和CP长度L;Step (1.1) selects the corresponding useful data part length N and CP length L in the traversal mode;

步骤(1.2)取解IQ调制后得到的数字基带信号数据,令其中的数据点对应的时域位置序号为θ,按照以下公式求出它所对应的相关值:Step (1.2) obtains the digital baseband signal data obtained after the IQ modulation, so that the time domain position serial number corresponding to the data point is θ, and obtains its corresponding correlation value according to the following formula:

CorCor (( θθ )) == || ΣΣ kk == θθ θθ ++ LL -- 11 weightweight (( modemode ,, kk -- θθ )) ·· [[ rr (( kk )) rr ** (( kk ++ NN )) ]] ||

其中,r(k)为接收到的DRM基带信号第k个数据,r*(k)代表共轭运算,weight(mode,k-θ)为权重函数,是工作模式和k的函数,其表达式为:Among them, r(k) is the kth data of the received DRM baseband signal, r * (k) represents the conjugate operation, weight (mode, k-θ) is a weight function, which is a function of the working mode and k, and its expression The formula is:

weightweight (( modemode ,, nno )) == 22 -- 66 nno ++ (( 11 -- 22 -- 55 LL modemode )) ,, 00 &le;&le; nno << LL modemode 22 ,, nno &Element;&Element; ZZ 11 ,, LL modemode 22 &le;&le; nno << LL modemode ,, nno &Element;&Element; ZZ

Lmode为La、Lb、Lc、Ld,分别表示A、B、C、D模式下的CP长度。L mode is La, Lb, Lc, and Ld, which represent the CP lengths in A, B, C, and D modes, respectively.

加权系数的大小,与码间串扰(ISI)干扰能量的分布有关,体现了CP中的数据点和与之对应的被复制数据点之间的相关性强弱。由于CP中越靠前的点受到前一个码元带来的ISI影响越大即ISI干扰能量越大,因此和被复制数据点之间的相关性越弱,对应的加权系数越小。本发明采用的加权函数简化了指数型的加权函数,对其做了线性化处理。在各鲁棒性模式下,CP前半部分对应一个分布在0到1范围内的线性递增函数,以2的指数次方为斜率是为了方便计算、减少硬件开销;CP后半部分对应的加权系数为1,这不仅是由于CP越靠后的点受到的ISI影响越小,同时也是由于ISI干扰能量主要集中在CP的前半部分,而在CP后半部分的能量很小以至于可以忽略不予考虑在内。The size of the weighting coefficient is related to the distribution of intersymbol interference (ISI) interference energy, which reflects the strength of the correlation between the data points in the CP and the corresponding copied data points. Since the earlier point in the CP is more affected by the ISI brought by the previous symbol, that is, the greater the ISI interference energy, the weaker the correlation with the copied data point, and the smaller the corresponding weighting coefficient. The weighting function adopted in the present invention simplifies the exponential weighting function and performs linearization processing on it. In each robustness mode, the first half of CP corresponds to a linear increasing function distributed in the range of 0 to 1, and the slope is to the power of 2 to facilitate calculation and reduce hardware overhead; the weighting coefficient corresponding to the second half of CP is 1, this is not only because the point behind the CP is less affected by ISI, but also because the ISI interference energy is mainly concentrated in the first half of the CP, while the energy in the second half of the CP is so small that it can be ignored within consideration.

步骤(2)将步骤(1)中遍历各鲁棒性模式时得到的四组相关值序列分别乘上四个常数。如果D模式对应的常数为1,那么A模式对应的常数可以在1.6到2.6范围内取值,B模式对应的常数可以在0.9到1.7范围内取值,C模式对应的常数可以在0.9到1.7范围内取值。之所以要乘上4个常数,是为了使全局最大值一定出现在相匹配的模式中,便于步骤(3)通过搜索全局最大值来判决模式。如果当前信号为A模式,由于A模式信号的CP很短,使得用A模式N、L参数计算得到的相关峰值不明显,与其它模式计算下的最大值相差很小,全局最大值不一定出现在A模式的相关值序列中,因此需要将A模式的相关值扩大一定倍数以使其出现明显的全局最大值;而如果当前信号为B、C或D模式,使用相匹配模式的N、L参数都能够得到非常明显的峰值,并且全局最大值的幅度存在一定的冗余,就算对其衰减一定倍数也不会有影响,但是衰减后的大小不能低于A模式相关值扩大后的大小,所以四个常数之间存在一定的制约关系。Step (2) Multiply the four sets of correlation value sequences obtained when traversing each robust mode in step (1) by four constants respectively. If the constant corresponding to mode D is 1, then the constant corresponding to mode A can take a value in the range of 1.6 to 2.6, the constant corresponding to mode B can take a value in the range of 0.9 to 1.7, and the constant corresponding to mode C can be in the range of 0.9 to 1.7 value within the range. The reason for multiplying by 4 constants is to make the global maximum appear in the matching pattern, so that step (3) can judge the pattern by searching the global maximum. If the current signal is in mode A, since the CP of the mode A signal is very short, the correlation peak calculated by using the N and L parameters of mode A is not obvious, and the difference from the maximum value calculated in other modes is very small, and the global maximum value does not necessarily appear In the correlation value sequence of mode A, it is necessary to expand the correlation value of mode A by a certain factor to make it appear an obvious global maximum; and if the current signal is B, C or D mode, use the matching mode N, L The parameters can get a very obvious peak value, and there is a certain redundancy in the magnitude of the global maximum value, even if it is attenuated by a certain multiple, it will not be affected, but the attenuated size cannot be lower than the expanded size of the related value of A mode. So there are certain constraints among the four constants.

步骤(3)搜索经过步骤(2)处理得到的四组相关值序列中的最大值,从中选出全局最大值,该全局最大值所在的模式为判决结果,至此鲁棒性模式检测完成。Step (3) Search for the maximum value in the four sets of correlation value sequences processed by step (2), and select the global maximum value. The mode in which the global maximum value is located is the judgment result. So far, the robust mode detection is completed.

本发明提出的DRM系统中的鲁棒性模式检测实现方法,其优点主要包括线性加权系数的引入能够抵消部分码间串扰的影响,不仅对伪峰值有抑制作用,而且计算复杂度相比指数加权形式下降了很多,硬件开销小,利于硬件的实现,在硬件字长有限的情况下能够准确存储加权系数;另外,对模式判决的依据不再采用繁琐的周期检测方法,而是通过调整相关值序列的大小来搜索全局最大值,借助全局最大值这种简单、直观的物理量来进行鲁棒性模式检测,不仅准确性极高,而且在信噪比下降的情况下,通过优化调整幅值的常数,仍然可以正确搜索出全局最大值出现在相匹配的模式中,以达到正确检测当前模式的目的。因此本发明提出的方法不仅准确性高,而且抗信噪比下降的能力强,甚至当信噪比降至很低时,可以通过优化用来调整相关值序列幅值的常数,来正确完成对鲁棒性模式的检测,具有很高的灵活性。The method for implementing robust pattern detection in the DRM system proposed by the present invention has the advantages that the introduction of linear weighting coefficients can offset the influence of part of the intersymbol crosstalk, which not only suppresses false peaks, but also has computational complexity compared to exponential weighting. The form has been greatly reduced, the hardware overhead is small, and it is beneficial to the realization of the hardware. In the case of limited hardware word length, the weighting coefficient can be accurately stored; The size of the sequence is used to search for the global maximum, and the simple and intuitive physical quantity of the global maximum is used to perform robust pattern detection. constant, it can still correctly search out that the global maximum value appears in the matching pattern, so as to achieve the purpose of correctly detecting the current pattern. Therefore, the method proposed in the present invention not only has high accuracy, but also has a strong ability to resist the decline of the signal-to-noise ratio. Robust pattern detection with high flexibility.

附图说明Description of drawings

图1是DRM系统中的鲁棒性模式检测实现方法涉及的电路原理模块。Fig. 1 shows the circuit principle modules involved in the implementation method of robust pattern detection in the DRM system.

图2是DRM系统中的鲁棒性模式检测实现方法的流程图。Fig. 2 is a flowchart of a method for implementing robust pattern detection in a DRM system.

具体实施方式Detailed ways

本发明提出的DRM系统中的鲁棒性模式检测实现方法,其所对应的电路原理模块由存储器、相关器、乘法器、比较器四个部分组成:The implementation method of robust pattern detection in the DRM system proposed by the present invention, its corresponding circuit principle module is composed of four parts: a memory, a correlator, a multiplier, and a comparator:

1)存储器用来存储数字基带信号,通过这些数据来进行后续的鲁棒性模式检测处理;1) The memory is used to store digital baseband signals, and the subsequent robust mode detection processing is performed through these data;

2)相关器在遍历四种鲁棒性模式时计算每个点对应的相关值,这样可以得到各鲁棒性模式对应的相关值序列。相关器采用如下公式计算每个点的相关值:2) The correlator calculates the correlation value corresponding to each point when traversing the four robustness modes, so that the correlation value sequence corresponding to each robustness mode can be obtained. The correlator uses the following formula to calculate the correlation value of each point:

CorCor (( &theta;&theta; )) == || &Sigma;&Sigma; kk == &theta;&theta; &theta;&theta; ++ LL -- 11 weightweight (( modemode ,, kk -- &theta;&theta; )) &CenterDot;&CenterDot; [[ rr (( kk )) rr ** (( kk ++ NN )) ]] ||

其中,N和L分别是当前遍历的鲁棒性模式所对应的有用数据部分长度和CP长度,weight(mode,k-θ)是当前遍历的鲁棒性模式所对应的加权函数,θ是该数据点的时域位置序号,r(k)为接收到的DRM基带信号第k个数据,r*(k)代表共轭运算。在相关器中作相关运算的两部分数据分别为从该数据点开始的L个数据和与该数据点往后间隔N个数据点开始的L个数据。采用线性加权来处理相关运算中的每一个乘积项,目的是抵消一部分的码间干扰,抑制伪峰值的生成,同时简化指数加权形式的计算复杂性;对线性加权相关的结果取模,能够去除小数倍频偏的影响;Among them, N and L are the useful data part length and CP length corresponding to the robustness mode currently traversed respectively, weight(mode, k-θ) is the weighting function corresponding to the robustness mode traversed currently, and θ is the The time domain position number of the data point, r(k) is the kth data of the received DRM baseband signal, and r * (k) represents the conjugate operation. The two parts of data for correlation operation in the correlator are L data starting from the data point and L data starting from N data points after the data point. Linear weighting is used to process each product item in the correlation operation, the purpose is to offset part of the intersymbol interference, suppress the generation of false peaks, and simplify the computational complexity of the exponential weighting form; the modulus of the linear weighted correlation results can be removed. The influence of fractional frequency offset;

3)利用乘法器将遍历得到的四组相关值序列分别乘以四个确定常数,以对其幅值大小进行调整,使得不仅能正确检测出全局最大值很明显的B、C、D模式,同时能正确检测出由于CP长度过短而峰值不明显的A模式;3) Use a multiplier to multiply the four sets of correlation value sequences obtained through traversal by four definite constants to adjust their amplitudes, so that not only can the B, C, and D modes with obvious global maximums be correctly detected, At the same time, it can correctly detect the A mode whose peak is not obvious because the CP length is too short;

4)通过比较器来搜索调整后的四组相关值序列中的全局最大值,该全局最大值对应的模式为鲁棒性模式检测的结果。4) The comparator is used to search for the global maximum in the adjusted four sets of correlation value sequences, and the pattern corresponding to the global maximum is the result of robust pattern detection.

上述遍历求相关的过程中,线性加权系数的确定方法为:In the process of traversing correlations above, the method of determining the linear weighting coefficient is:

weightweight (( modemode ,, nno )) == 22 -- 66 nno ++ (( 11 -- 22 -- 55 LL modemode )) ,, 00 &le;&le; nno << LL modemode 22 ,, nno &Element;&Element; ZZ 11 ,, LL modemode 22 &le;&le; nno << LL modemode ,, nno &Element;&Element; ZZ

其中Lmode为La、Lb、Lc、Ld,分别表示A、B、C、D模式的CP长度。Wherein, L mode is La, Lb, Lc, and Ld, which represent the CP lengths of A, B, C, and D modes, respectively.

在各鲁捧性模式下,加权系数在CP前半部分为一个分布在0到1范围内的线性递增函数,以2的指数次方为斜率是为了方便计算、减少硬件开销;在CP后半部分为1,这不仅是由于CP越靠后的点受到的ISI影响越小,同时也是由于ISI干扰能量主要集中在CP的前半部分,而在CP后半部分的能量很小以至于可以忽略不予考虑在内。In each robustness mode, the weighting coefficient is a linear increasing function distributed in the range of 0 to 1 in the first half of CP, and the slope is to the power of 2 to facilitate calculation and reduce hardware overhead; in the second half of CP is 1, this is not only because the point behind the CP is less affected by ISI, but also because the ISI interference energy is mainly concentrated in the first half of the CP, while the energy in the second half of the CP is so small that it can be ignored within consideration.

上述调整相关值序列的过程中,各鲁棒性模式所对应的常数确定方法为:In the above process of adjusting the correlation value sequence, the constants corresponding to each robustness mode are determined as follows:

目前采用的鲁棒性模式检测方法失效的原因是由于A模式的CP长度太短,使得峰值及其周期性不明显,从而造成了对A模式的误判。因此,本发明中提出的鲁棒性模式检测实现方法针对这一问题,改变模式判决依据,通过搜索全局最大值来检测模式。对遍历相关求得的四组相关值序列分别乘上四个确定常数,以使得全局最大值一定出现在相匹配的模式中,便于模式的检测。如果当前信号为A模式,由于A模式信号的CP很短,使得用A模式N、L参数计算得到的相关峰值不明显,与其它模式计算下的最大值相差很小,全局最大值不一定出现在A模式的相关值序列中,因此需要将A模式的相关值扩大一定倍数以使其出现明显的全局最大值;而如果当前信号为B、C或D模式,使用匹配模式的N、L参数都能够得到非常明显的峰值,并且全局最大值的幅度存在一定的冗余,就算对其衰减一定倍数也不会有影响,但是衰减后的大小不能低于A模式相关值扩大后的大小,所以四个常数之间存在一定的制约关系。The reason for the failure of the currently used robust mode detection method is that the CP length of the A mode is too short, so that the peak value and its periodicity are not obvious, thus causing a misjudgment of the A mode. Therefore, the robust mode detection implementation method proposed in the present invention aims at this problem, changes the mode decision basis, and detects the mode by searching for the global maximum value. The four sets of correlation value sequences obtained by ergodic correlation are multiplied by four constants, so that the global maximum must appear in the matching pattern, which is convenient for pattern detection. If the current signal is in mode A, since the CP of the mode A signal is very short, the correlation peak calculated by using the N and L parameters of mode A is not obvious, and the difference from the maximum value calculated in other modes is very small, and the global maximum value does not necessarily appear In the correlation value sequence of mode A, it is necessary to expand the correlation value of mode A by a certain factor to make it appear an obvious global maximum; and if the current signal is mode B, C or D, use the N and L parameters of the matching mode Both can get very obvious peaks, and there is a certain redundancy in the magnitude of the global maximum value, even if it is attenuated by a certain multiple, it will not be affected, but the attenuated size cannot be lower than the expanded size of the A-mode correlation value, so There are certain constraints among the four constants.

以下结合附图,详细说明本发明的内容:Below in conjunction with accompanying drawing, describe content of the present invention in detail:

图1是DRM系统中的鲁棒性模式检测实现方法涉及的电路原理模块。如图1所示,鲁棒性模式检测的实现跟在射频前端处理和解IQ调制模块之后。首先存储一定长度的解IQ调制得到的数字基带信号,如5个A模式码元长度的基带信号,用这些数据进行后续的鲁棒性模式检测处理。然后遍历各种鲁棒性模式的N、L参数,当取定一种鲁棒性模式时,选择该模式对应的N和L值,对存储的数据点依次利用本方法所采用的线性加权相关取模表达式通过相关器计算其对应的相关值,这样可以得到对应四种鲁棒性模式的四组相关值序列。为了正确识别出CP很短的A模式,同时又不影响对其他模式的判决情况,引入了分别用于调整四组相关值序列的四个常数,利用乘法器将常数乘到对应的相关值序列上,便于之后的比较器能够正确搜索出全局最大值。最后通过比较器来搜索乘法器输出的相关值序列中的全局最大值。无论在哪种鲁棒性模式下,搜索出的全局最大值一定出现在相匹配的模式中,正确完成了鲁棒性模式的检测。Fig. 1 shows the circuit principle modules involved in the implementation method of robust pattern detection in the DRM system. As shown in Figure 1, the implementation of robust pattern detection follows the RF front-end processing and IQ modulation modules. First store a certain length of digital baseband signals obtained by de-IQ modulation, such as baseband signals with a length of 5 A-mode symbols, and use these data to perform subsequent robust mode detection processing. Then traverse the N and L parameters of various robustness modes. When a robustness mode is selected, select the corresponding N and L values of the mode, and sequentially use the linear weighted correlation adopted by this method for the stored data points. The modulo expression calculates its corresponding correlation value through the correlator, so that four sets of correlation value sequences corresponding to the four robustness modes can be obtained. In order to correctly identify the A mode with a very short CP without affecting the judgment of other modes, four constants are introduced to adjust the four sets of correlation value sequences, and the multipliers are used to multiply the constants to the corresponding correlation value sequences , so that the subsequent comparator can correctly search for the global maximum value. Finally, a comparator is used to search for the global maximum in the correlation value sequence output by the multiplier. No matter in which robust mode, the searched global maximum value must appear in the matching mode, and the detection of the robust mode is completed correctly.

图2是DRM系统中的鲁棒性模式检测实现方法的流程图。如图2所示,本发明提出的DRM系统中鲁棒性模式检测实现方法的具体过程为:Fig. 2 is a flowchart of a method for implementing robust pattern detection in a DRM system. As shown in Figure 2, the specific process of the robust pattern detection implementation method in the DRM system proposed by the present invention is:

1)从经接收机射频前端和解IQ调制处理得到的数字基带信号中读入一定长度的数据,如5个A模式码元长度即5(Na+La)个数据点,存放在存储器中供鲁棒性模式检测所用;1) Read data of a certain length from the digital baseband signal obtained by the RF front end of the receiver and the IQ modulation process, such as 5 A-mode symbol lengths, that is, 5 (Na+La) data points, and store them in the memory for Lu Used for sticky mode detection;

2)取A模式对应的有用数据部分长度Na和CP长度La,对存放在存储器中的前面部分的数据点如前5(Na+La)-(Na+La)个数据点,依次通过相关器计算线性加权相关取模的值,所用的公式为:2) Take the useful data part length Na and CP length La corresponding to the A mode, and for the data points of the front part stored in the memory, such as the first 5 (Na+La)-(Na+La) data points, pass through the correlator in turn To calculate the value of linear weighted correlation modulo, the formula used is:

CorCor (( &theta;&theta; )) == || &Sigma;&Sigma; kk == &theta;&theta; &theta;&theta; ++ LL -- 11 weightweight (( modemode ,, kk -- &theta;&theta; )) &CenterDot;&Center Dot; [[ rr (( kk )) rr ** (( kk ++ NN )) ]] ||

其中,N=Na,L=La,θ为该数据点的时域位置序号,Among them, N=Na, L=La, θ is the time-domain position sequence number of the data point,

权重系数 weight ( mode , n ) = 2 - 6 n + ( 1 - 2 - 5 L mode ) , 0 &le; n < L mode 2 , n &Element; Z 1 , L mode 2 &le; n < L mode , n &Element; Z weight factor weight ( mode , no ) = 2 - 6 no + ( 1 - 2 - 5 L mode ) , 0 &le; no < L mode 2 , no &Element; Z 1 , L mode 2 &le; no < L mode , no &Element; Z

这样将求得一组对应于A模式的相关值序列;In this way, a set of correlation value sequences corresponding to the A mode will be obtained;

3)取B模式对应的有用数据部分长度Nb和CP长度Lb,对存放在存储器中的前面部分的数据点如前5(Na+La)-(Nb+Lb)个数据点,依次通过相关器计算线性加权相关取模的值,所用的公式为:3) Take the useful data part length Nb and CP length Lb corresponding to the B mode, and store the data points in the front part of the memory, such as the first 5 (Na+La)-(Nb+Lb) data points, through the correlator in turn To calculate the value of linear weighted correlation modulo, the formula used is:

CorCor (( &theta;&theta; )) == || &Sigma;&Sigma; kk == &theta;&theta; &theta;&theta; ++ LL -- 11 weightweight (( modemode ,, kk -- &theta;&theta; )) &CenterDot;&CenterDot; [[ rr (( kk )) rr ** (( kk ++ NN )) ]] ||

其中,N=Nb,L=Lb,θ为该数据点的时域位置序号,Among them, N=Nb, L=Lb, θ is the time-domain position number of the data point,

权重系数 weight ( mode , n ) = 2 - 6 n + ( 1 - 2 - 5 L mode ) , 0 &le; n < L mode 2 , n &Element; Z 1 , L mode 2 &le; n < L mode , n &Element; Z weight factor weight ( mode , no ) = 2 - 6 no + ( 1 - 2 - 5 L mode ) , 0 &le; no < L mode 2 , no &Element; Z 1 , L mode 2 &le; no < L mode , no &Element; Z

这样将求得一组对应于B模式的相关值序列;In this way, a set of correlation value sequences corresponding to the B mode will be obtained;

4)取C模式对应的有用数据部分长度Nc和CP长度Lc,对存放在存储器中的前面部分的数据点如前5(Na+La)-(Nc+Lc)个数据点,依次通过相关器计算线性加权相关取模的值,所用的公式为:4) Take the useful data part length Nc and CP length Lc corresponding to the C mode, and store the data points in the front part of the memory, such as the first 5 (Na+La)-(Nc+Lc) data points, through the correlator in turn To calculate the value of linear weighted correlation modulo, the formula used is:

CorCor (( &theta;&theta; )) == || &Sigma;&Sigma; kk == &theta;&theta; &theta;&theta; ++ LL -- 11 weightweight (( modemode ,, kk -- &theta;&theta; )) &CenterDot;&CenterDot; [[ rr (( kk )) rr ** (( kk ++ NN )) ]] ||

其中,N=Nc,L=Lc,θ为该数据点的时域位置序号,Among them, N=Nc, L=Lc, θ is the time-domain position number of the data point,

权重系数 weight ( mode , n ) = 2 - 6 n + ( 1 - 2 - 5 L mode ) , 0 &le; n < L mode 2 , n &Element; Z 1 , L mode 2 &le; n < L mode , n &Element; Z weight factor weight ( mode , no ) = 2 - 6 no + ( 1 - 2 - 5 L mode ) , 0 &le; no < L mode 2 , no &Element; Z 1 , L mode 2 &le; no < L mode , no &Element; Z

这样将求得一组对应于C模式的相关值序列;In this way, a set of correlation value sequences corresponding to the C mode will be obtained;

5)取D模式对应的有用数据部分长度Nd和CP长度Ld,对存放在存储器中的前面部分的数据点如前5(Na+La)-(Nd+Ld)个数据点,依次通过相关器计算线性加权相关取模的值,所用的公式为:5) Take the useful data part length Nd and CP length Ld corresponding to the D mode, and store the data points in the front part of the memory, such as the first 5 (Na+La)-(Nd+Ld) data points, through the correlator in turn To calculate the value of linear weighted correlation modulo, the formula used is:

CorCor (( &theta;&theta; )) == || &Sigma;&Sigma; kk == &theta;&theta; &theta;&theta; ++ LL -- 11 weightweight (( modemode ,, kk -- &theta;&theta; )) &CenterDot;&Center Dot; [[ rr (( kk )) rr ** (( kk ++ NN )) ]] ||

其中,N=Nd,L=La,θ为该数据点的时域位置序号,Wherein, N=Nd, L=La, θ is the time-domain position sequence number of the data point,

权重系数 weight ( mode , n ) = 2 - 6 n + ( 1 - 2 - 5 L mode ) , 0 &le; n < L mode 2 , n &Element; Z 1 , L mode 2 &le; n < L mode , n &Element; Z weight factor weight ( mode , no ) = 2 - 6 no + ( 1 - 2 - 5 L mode ) , 0 &le; no < L mode 2 , no &Element; Z 1 , L mode 2 &le; no < L mode , no &Element; Z

这样将求得一组对应于D模式的相关值序列;In this way, a set of correlation value sequences corresponding to the D mode will be obtained;

6)利用乘法器将A模式下的相关值序列乘上一个确定常数;6) Using a multiplier to multiply the correlation value sequence under the A mode by a definite constant;

7)利用乘法器将B模式下的相关值序列乘上一个确定常数;7) Using a multiplier to multiply the correlation value sequence under the B mode by a definite constant;

8)利用乘法器将C模式下的相关值序列乘上一个确定常数;8) Using a multiplier to multiply the correlation value sequence under the C mode by a definite constant;

9)利用乘法器将D模式下的相关值序列乘上一个确定常数;9) using a multiplier to multiply the correlation value sequence in the D mode by a certain constant;

10)通过比较器搜索四组相关值序列中的全局最大值;10) search for the global maximum in the four groups of correlation value sequences by a comparator;

11)判决模式,以全局最大值对应的模式为鲁棒性模式检测结果。11) Judgment mode, the mode corresponding to the global maximum value is the robustness mode detection result.

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
Cor ( &theta; ) = | &Sigma; k = &theta; &theta; + L - 1 weight ( mode , k - &theta; ) &CenterDot; [ r ( k ) r * ( k + N ) ] | ,
Wherein:
Weight (mode, k-θ) is a weighting function, is the function of described robustness pattern and k, represents with following formula:
weight ( mode , n ) = 2 - 6 n + ( 1 - 2 - 5 L mode ) , 0 &le; n < L mode 2 , n &Element; Z 1 , L mode 2 &le; n < L mode , n &Element; Z ,
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.
CN2007101779997A 2007-11-23 2007-11-23 Robustness pattern detection implementing method of global digital broadcasting system Expired - Fee Related CN101247204B (en)

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