CN100539457C - Long-period spread spectrum code double-folding capture searching method - Google Patents

Long-period spread spectrum code double-folding capture searching method Download PDF

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CN100539457C
CN100539457C CN 200710064680 CN200710064680A CN100539457C CN 100539457 C CN100539457 C CN 100539457C CN 200710064680 CN200710064680 CN 200710064680 CN 200710064680 A CN200710064680 A CN 200710064680A CN 100539457 C CN100539457 C CN 100539457C
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step
spreading code
sequence
folding
code
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CN101022282A (en )
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冯振明
崔晓伟
洪 李
陆明泉
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清华大学
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Abstract

本发明属于扩频通信中的扩频码捕获技术领域,其特征在于,针对使用长周期扩频码,或是使用扩频码做同步码的通信系统,在接收端对接收信号和本地伪码同时进行折叠,对折叠后的信号分别进行FFT变换到频域并将这两个频域数据对应共轭相乘,然后将相乘后的数据通过IFFT反变换到时域,在时域计算各点功率最大值并与预定门限值比较,如果计算出的最大点功率值低于预定门限值,则调整本地码相位重新进行搜索,直至计算出的功率最大值大于预定门限值,此时在产生的本地码相位中按照已有捕获算法搜索各点码相位,该算法在提高长周期扩频码码相位搜索速度,保证信号处理增益的同时,没有增加硬件实现复杂度。 The present invention pertains to a spreading code in a spread spectrum communication technical field capture, wherein the communication system to make use of preambles for the long period spreading code, spreading code or use, the receiving side the received signal and the local pseudocode by folding, the folding of the signal after the FFT into the frequency domain and the frequency domain data corresponding to these two conjugate multiplication, the data is then multiplied by the inverse transformation into the time domain the IFFT, are calculated in the time domain, the maximum power point and compared with a predetermined threshold value, if the calculated value of the maximum power point is below the predetermined threshold value, the local code phase is adjusted to re-search until the calculated power is larger than a predetermined maximum threshold value, this when the locally generated code phase acquisition algorithm according to established code phase search for each point, the algorithm can improve the long period spreading code phase search speed, to ensure that the signal processing gain, no increase in hardware complexity.

Description

长周期扩频码的双折叠捕获搜索方法 Double folding the long period spreading code acquisition search method

技术领域 FIELD

本发明涉及使用长周期扩频码通信的系统,或是使用扩频码做同步码的通信系统中,一种扩频码快速捕获的算法。 The present invention relates to a communication system of the long period spreading codes, or spreading codes to use to make a communication system synchronization code, spread spectrum code acquisition algorithm. 背景技术 Background technique

扩频通信具有很多优点,应用甚广。 Spread spectrum communication has many advantages, wide application. 扩频信号可以对抗或者抑制干扰的有害影响,例如信道中其他用户引起的干扰;扩频信号以低功率发送来隐蔽信号,使得信号难以被窃听者检观IJ到;可以实现保密通信。 Spread signal can resist or suppress the deleterious effects of interference, for example interference caused by other users of the channel; the spread spectrum signal transmitted at low power for concealing signal so that the signal detection concept difficult for eavesdroppers to IJ; secure communication can be achieved. 扩频通信技术广泛应用于军事、民用等领域。 Spread spectrum communication technology is widely used in military and civilian fields.

第三代移动通信(3G)通信的3个主要标准WCDMA、 TD-SCDMA、 CDMA-2000都是以扩频通信技术为基础的。 Third generation mobile communication (3G) 3 major WCDMA communication standard, TD-SCDMA, CDMA-2000 are based on spread spectrum technology based communications. 目前应用最广的卫星导航系统——全球定位系统(GPS),也是以扩频通信技术为基础的。 Currently the most widely used satellite navigation system - Global Positioning System (GPS), also based on spread spectrum communication technology-based. 码捕获则是实现扩频通信的根本基础。 Code acquisition is the realization of the fundamental basis of the spread spectrum communication. 只有完成了码捕获才能在接收端与发射端建立同步,才能在接收端实现解扩,完成信号处理功能。 Only after code acquisition to establish synchronization at the receiving end and the transmitting end to the receiving end in the despreading, a signal processing function is completed. 比较典型的扩频码捕获算法有非折叠补零算法和扩展复制重叠捕获搜索技术。 Typical spreading code acquisition algorithm with a non-zero-padding is folded and extended copy algorithm overlapping capture search technique.

非折叠补零算法,是国际上比较常用的一种长周期扩频码捕获搜索算法。 Unfolded zero-padding algorithm is more commonly used internationally a long-period spreading code acquisition search algorithm. 利用相关与巻积以及巻积与离散傅立叶变换(DFT)的关系,相关运算可以用快速傅立叶变换(FFT)来实现。 And using the correlation relationship with convolving convolving a discrete Fourier transform (DFT), the correlation calculation may be a fast Fourier transform (FFT) to achieve. 若能在实现相关前对接收信号(或本地伪码)进行补零操作,则可以利用FFT来达到并行搜索码相位的目的。 Zero padding operation if the received signal (or local pseudo-code) before the implementation-dependent, the FFT can be used to achieve the purpose of the parallel code phase search.

非折叠补零算法原理图如图1所示。 Zero-padding algorithm unfolded diagram shown in Fig. 首先对接收到的信号进行分段补零操作,并进行FFT 运算(在此记分段长度为W,补零个数为7V/2)。 First received signal segment the zero padding operation, and performs the FFT operation (herein referred to as segment length W, the number of zero padding 7V / 2). 对本地伪随机扩频码进行分段、FFT操作。 Local pseudorandom spreading code is segmented, FFT operation. 然后将它们FFT后的结果进行共轭相乘和傅立叶反变换(IFFT)。 The result of FFT are then conjugate multiplication and inverse Fourier transform (IFFT). 对IFFT的结果进行功率检测,从中找出最大值(或大于设定门限者)进行跟踪检测。 IFFT is performed on the power detection results, to find out the maximum value (or greater than the set threshold by) track detection. 由于IFFT所得结果中后一半的值即为接收信号与本地伪码在7V/2个不同码相位单元上相关后的值,因此该方法达到了并行搜索iV/2个码相位的目的。 Because half of the value of the received signal is the pseudo-code associated with the local on 7V / 2 units different code phases obtained after IFFT result, this method achieves the object of the parallel search iV / 2 of the code phases.

该方法利用FFT实现了码相位的并行搜索,提高了搜索速度。 The method uses a FFT with parallel search code phase, the search speed increase. 但存在以下问题:(1)并行搜索码相位的能力较弱,搜索速度较慢。 However, the following problems: (1) the ability of the parallel code phase search is weak, the search speed is slow. 以FFT长度为iV,补零个数为iV/2为例,该方法每次只能并行搜索iV/2个码相位。 In FFT length iV, an example of the number of zero padding iV / 2, the parallel search method can only iV / 2 code phases. (2)相干积分时间较短,捕获性能较差。 (2) a short coherent integration time, poor capturing performance. 同样以FFT长度 Also to FFT length

为AA,补零个数为W/2为例,该方法预检测积分时间仅为(i^A0/2,其中"为采样周期。扩展复制重叠捕获搜索技术(XFAST, Extended replica Folding Acquisition Search Technique)是指对信号先进行分段,然后再对应相加,如图2所示。XFAST原理图如图3所示,其折叠是指对本地伪码信号进行折叠。选择N点(N可以取任意正整数,为方便FFT运算, 一般N为2的次幂)经前端模拟数字转换器件A/D采样后的接收信号,并对该信号进行FFT处理。根据需要,可以对FFT运算后的结果再进行抗干扰、去除载波多普勒等处理。根据接收信号的时间不确定度,确定待搜索的码相位范围,并产生本地伪码信号。对产生的本地伪码信号进行折叠(假定本地伪码信号折叠次数为4,则每次需要选择4iV点本地伪码信号进行折叠)和FFT、共轭处理,然后与接收信号FFT (或去除多普勒)后的结果进行相乘。 For the AA, the number of zeros up to W / 2, for example, the method of pre-detection integration time of only (i ^ A0 / 2, where 'is the sampling period. Extended Copy overlapping capture search technique (XFAST, Extended replica Folding Acquisition Search Technique ) refers to a signal for the first segment, and then corresponding to the sum, as shown in FIG .XFAST diagram shown in Figure, it is folded refers to the local pseudo-code signal 23 is folded. select N-point (N may take any positive integer, for the convenience of the FFT operation, typically N is a power of 2) sampling the received signal by the analog-digital conversion device front end a / D, and the signal subjected to FFT processing. necessary, the results of the FFT operation then interference, Doppler processing such as removal of the carrier. the time uncertainty of the received signal, determining the range of code phases to be searched, and generates a local pseudo-code signal for a local pseudo-code signal generated by folding (assuming pseudo local 4 as the number of folds code signal, each time it needs to select a local pseudo-code signal point 4iV folding) and an FFT, conjugation process, then the received signal FFT (or Doppler removal results) are multiplied. 相乘后的结果进行傅立叶反变换(IFFT)和功率检测。若功率检测发现有比门限大者,则说明接收信号的码相位可能落在本地伪码段以内。此时应再对本地折叠的4段伪码进行逐个搜索,直到找出与接收信号对齐的那个码相位——去模糊度。若功率检测没有发现比门限大的值出现,则移动本地码相位,产生另一段本地伪码再次进行搜索,直到发现比门限大者, 然后再进行去模糊度操作。 Multiplying the result of inverse Fourier transform (IFFT) and the power detection. If the power detection found is greater than the threshold, then the code phase of the received signal may fall within a local pseudo-code segments. In this case should be re-folding of the local 4-by-segment pseudo-code search, until you find the code phase of the received signal alignment - If the power detector to blur degree is found greater than the threshold value occurs, the mobile phase of the local code, pseudo-code is generated again another piece of local search, until you find the larger than the threshold, then to go ambiguity operations.

XFAST可以显著地提高算法的码相位搜索能力。 XFAST can significantly improve the ability of the code phase search algorithm. 例如若每段分组长度为W,折叠次数为 For example, if the packet length of each segment is W, the number of folding

M,则该算法一次便能并行搜索(Ml)iV个码相位,与非折叠补零算法每次只能并行搜索7V/2个码相位相比,其速度是它的2(Af-l)倍。 M, then the algorithm will be able to parallel search time (Ml) iV code phases, and non-zero-padding folded parallel search algorithm can only 7V / 2 compared to the code phases, its speed is 2 (Af-l) times. 例如般=4,则其速度是非折叠补零算法的6 Like e.g. = 4, then the speed is non-zero padding folded Algorithm 6

倍,使搜索速度成倍加快。 Times, speed up the search speed doubled.

该方法的突出优点是通过对本地伪码进行折叠,直接减少了待搜索的码相位单元数,从而使搜索速度成倍提高。 The outstanding advantage of the method is carried out by folding the local pseudo-code, the code directly reduce the number of phases to be searched unit, so that the search speed is doubled. 但该算法的捕获性能却随折叠次数的增加而急剧下降。 However, acquisition performance of the algorithm, but with the increasing number of folding decreases sharply. 例如若本地伪码折叠次数为2,则该算法并行搜索码相位的能力是非折叠补零算法的2倍,但捕获性能却下降了3dB;若本地信号折叠次数为20,则该算法并行搜索码相位的能力是非折叠补零算法的38倍,但捕获性能却下降了13dB。 For example, if a local pseudo-code the number of folds is 2, then the algorithm for parallel double capacity non-folding zero padding algorithm search code phases, but the acquisition performance has declined 3dB; if the local signal number of folds 20, the algorithm parallel search code the ability to non-folding phase zero padding algorithm 38 times, but the acquisition performance has declined 13dB. 因此该算法仅适用于捕获信噪比较高的长周期扩频码信号。 Thus the algorithm to capture only a high SNR long period spreading code signal. 发明内容 SUMMARY

本发明的特征在于,针对使用长周期扩频码通信的系统,或是使用扩频码做同步码的通 Feature of the present invention is made through the preamble spreading code for communication systems using the long period spreading code or use

信系统,在接收端依次按以下步骤用一块数字集成电路芯片做扩频码的双折叠同步捕获: Communication system, synchronization acquisition in the receiving side sequentially by the spread code to do the steps of a digital integrated circuit chip with a double folding:

步骤(1)在该数字集成电路中,设定该扩频通信中,生成的本地扩频码为C,,单次积分 Step (1) in the digital integrated circuit, sets the spread spectrum communication, the generated local spreading code C ,, single integral

分组长度为N,扩频码折叠次数为M,接收信号折叠次数为K,扩频捕获功率门限值A,其中i=0,l....步骤(2)设定接收机通过模拟到数字采样器件A/D采样后得到序列为《, Packet length is N, the number of spreading codes folding is M, the received signal is a folding times K, the spreading capture power threshold value A, where i = 0, l .... Step (2) is set to the receiver through the analog device digital sampling A / D obtained sequence is "sampled,

步骤(3)对步骤(2)的采样信号X,截取长度为KN点的数据,并进行折叠计算,得到序列 Step (3) Step (2) of the sampled signal X, KN intercept length data point, and folded calculated to obtain sequence

步骤(4)对步骤(1)的本地生成扩频码为C,截取长度为MN点的数据,进行折叠计算,得 Locally generated spreading code in step (4) of the step (1) is C, the length of the interception of data points MN, folding calculations give

到序列c,p, The sequence c, p,

步骤(5)对步骤(3)得到的折叠序列Z,进行FFT变换到频域,得到序列I7, Step (5) in step (3) to give the folded sequence Z, performs FFT into the frequency domain, to obtain sequence I7,

步骤(6)对步骤(4)得到的折叠序列C卩进行FFT变换到频域,得到序列D,, Step (6) of step (4) to give the folded sequence C Jie performs FFT into the frequency domain, to obtain sequence D ,,

步骤(7)对步骤(5)和步骤(6)得到的序列C和i^共轭相乘,并进行IFFT处理变换回 Step (7) of step (5) and (6) and the resulting sequence C i ^ conjugate multiplication, conversion back and IFFT processing

时域,得到序列Ef, A time domain to obtain Ef of the sequence,

步骤(8)对步骤(7)得到的序列《P进行功率检测,并从中找出功率最大值《自, Step (8) step (7) to give the sequence "P performs power detection, and find out the maximum power" since,

步骤(9)如果步骤(8)计算得到的功率最大值ilx小于功率门限值户。 Step (9) If in step (8) the maximum value of the calculated power is smaller than the power threshold value ilx households. ,则重新选取本地扩 , Then re-select the local expansion

频码Cf ,并重复步骤(4)至(9),直至利用第j次选取的本地扩频码C,基础得到的尸,大 Frequency of Cf code, and repeating steps (4) to (9), until a selected j-th use of local spreading codes C, were obtained using dead, large

于等于《为止, To equal "so far,

步骤(10)在第j次选取的扩频码C,上,用非折叠补零算法进行捕获,对相应的MV点 Step (10) at the selected spread code C j-th, on the capture of non fold zero-padding algorithm, the corresponding point MV

本地伪码相位进行搜索,找出与接收信号对齐的本地伪码相位。 Local code phase search, find the local code phase of the received signal alignment.

本发明在提高算法对长周期扩频码码相位单元并行搜索能力的同时,提高算法的捕获性能,从而达到提高长周期扩频码搜索速度的目的。 The present invention, while improving the ability of the search algorithm for parallel long period spreading code phase unit, to improve acquisition performance of the algorithm, so as to improve the long period spreading code search speed.

附图说明 BRIEF DESCRIPTION

图l是非折叠补零算法原理图。 Figure l is a non zero padding algorithm schematic folded.

图2是数据折叠处理示意图。 FIG 2 is a diagram of a data processing folding. 其中图(a)是原始采样信号的数据示意图;图(b)是对采样信号进 FIG wherein (a) is a schematic view of an original sampled data signal; (b) of the sampled signal into a

行分组的数据示意图,分为了4组,分别以'o', , 'x, , ' + ,标注;图(c)是对四组 Data packets schematic row, divided into 4 groups, respectively, 'o',, 'x,,' +, marked; FIG. (C) is four

分组信号进行对应相加后的数据示意图。 A schematic view of a packet signal corresponding to the summed data.

图3是扩展复制重叠捕获搜索算法(XFAST)的原理图。 Figure 3 is extended copy capture overlapping search algorithm (XFAST) schematic.

图4是双折叠捕获搜索算法原理图。 FIG 4 is a double-folded acquisition search algorithm schematics.

图5至图7是非折叠补零算法、扩展复制重叠捕获搜索算法与双折叠捕获搜索算法的仿真性能比较示意图。 5 to 7 are non-zero padding algorithm folded, overlapping capture extended copy search algorithm search algorithm simulation performance comparison with the double-folded schematic capture. 其中图5(a)代表非折叠补零算法;图5 (b)至图5 (d)、图6 (a)至图6 (d) 分别代表在k=2, 4, 6, 8, 12, 16, 19 (M均为20)情况下的双折叠捕获搜索算法。 Wherein FIG. 5 (a) represents a non-folded zero padding algorithm; FIG. 5 (b) to 5 (d), FIG. 6 (a) to 6 (d) represent the k = 2, 4, 6, 8, 12 , 16, double-folded at 19 (M 20 both) where acquisition search algorithm. 图7 (a)至图7 (d)代表M为20,非相干累加次数分别为2、 4、 6、 8情况下的扩展复制重叠捕获搜索算法。 FIG. 7 (a) to 7 (d) represents M is 20, the number of non-coherent accumulation are 2, 4, 6, 8 in the case of extended copy overlap acquisition search algorithm. 具体实施方式 detailed description

下面结合附图和实例,对本发明效果作具体介绍: In conjunction with the accompanying drawings and the following examples, the effect of the present invention will be specifically described:

在本实施例中,选取单次积分分组长度为N4024,扩频码折叠次数为M=20,接收信号折叠次数为K二6,扩频捕获功率门限值A,在接收端依次按以下步骤用一块数字集成电路芯 In the present embodiment, the selection of a single integrated packet length N4024, folding number of spreading codes M = 20, the received signal is K = number of folds 6, spreading capture power threshold value A, the following steps in sequence at the receiving end with a digital integrated circuit die

片做扩频码的双折叠同步捕获: Sheet made spreading code synchronization acquisition double folding:

步骤(1)在该数字集成电路中,设定该扩频通信中,生成的本地扩频码为C,, Step (1) in the digital integrated circuit, sets the spread spectrum communication, the generated local spreading code C ,,

步骤(2)设定接收机通过模拟到数字采样器件A/D采样后得到序列为《, Step (2) is set to the receiver through the analog sequence is obtained "after the digital sampling device A / D sampling,

步骤(3)对步骤(2)的采样信号Z,截取长度为6144点的数据,分为6组,每组1024 Step (3) Step (2) of the sampled signal Z, intercept data length of 6144 points, divided into 6 groups 1024

点,进行折叠计算,得到序列义,, Point, folding calculation, the sequence of the sense ,,

步骤(4)对步骤(1)的本地生成扩频码为C,截取长度为20480点的数据,分为20组, Locally generated spreading code in step (4) of the step (1) is C, a data length 20480 intercept point, divided into 20 groups,

每组1024点进行折叠计算,得到序列C,, 1024 fold each point is calculated, to obtain sequence C ,,

步骤(5)对步骤(3)得到的折叠序列;^进行FFT变换到频域,得到序列}7, 步骤(6)对步骤(4)得到的折叠序列Cf进行FFT变换到频域,得到序列i^, 步骤(7)对步骤(5)和步骤(6)得到的序列17和"/^共轭相乘,并进行IFFT处理变换 Step (5) in step (3) is folded sequence obtained; ^ performs FFT into the frequency domain, to obtain sequence} 7, step (6) of step (4) is folded sequence Cf was subjected to FFT into the frequency domain, to obtain sequence ^ I, step (7) of step (5) and (6) the resulting sequence 17 and "/ ^ conjugate of conversion and IFFT processing

回时域,得到序列E,P, Back to the time domain to obtain sequences E, P,

步骤(8)对步骤(7)得到的序列五f进行功率检测,并从中找出功率最大值/^x, Step (8) step (7) obtained five sequences f performs power detection, and find out the maximum power / ^ x,

步骤(9)如果步骤(8)计算得到的功率最大值/Lx小于功率门限值《,则移动14336 Step (9) If in step (8) the maximum value calculated by the power / Lx is less than the power threshold value ", the mobile 14336

点本地伪码重新选取本地扩频码C,,并重复步骤(4)至(9),直至利用第j次选取的本地 Reselecting local point pseudocode local spreading code C ,, and repeating steps (4) to (9), until a selected using the j th local

扩频码c,基础得到的pmax大于等于《为止, Spreading code C, were obtained using greater than or equal pmax "up,

步骤(10)在第j次选取的扩频码Cf上,用非折叠补零算法进行捕获,对相应的20480 点本地伪码相位进行搜索,找出与接收信号对齐的本地伪码相位。 Step (10) at the selected j-th spreading code of Cf, with a non-zero-padding algorithm capture folded, the respective local code phase search 20480 points, find the local code phase of the received signal alignment. 下面通过对比双折叠捕获算法和已有算法,说明本发明的发明效果。 The following acquisition algorithm by comparing the bi-fold and existing algorithms, the effects of the present invention. 设定接收信号信噪比^\^ = -12dB,载波多普勒为100Hz,码相位偏移为500个采样点。 Setting a received signal SNR ^ \ ^ = -12dB, Doppler carrier to 100Hz, the code phase offset of 500 sampling points. 在不同接收信号折叠次数K和非相干累积次数情况不,比较了"非折叠补零算法"、"扩展复制重叠捕获搜索算法"、"双折叠捕获搜索算法"三种算法的捕获性能。 Folding the received signal at different times K and the number of non-coherent accumulation without comparing the "non-zero-padded folding algorithm", "extended copy overlap acquisition search algorithm", "double-folded acquisition search algorithm" Capture Performance of the three algorithms. 为了比较"扩展复制重叠捕获搜索算法"和"双折叠捕获搜索算法",本地信号折叠次数M均为20。 To compare the "capture overlapping search algorithm extended copy" and "double-folded acquisition search algorithm", the local signal frequency M was 20 fold.

图5(a)表示"非折叠补零算法",其非相干累积次数为l (即未进行非相干累加),从图中可以看到在该仿真条件下,"非折叠补零算法"在第500点处的相关峰很突出,能找到正确的码相位位置。 FIG 5 (a) represents a "zero-padding algorithm unfolded", the number of non-coherent accumulation or l (a i.e. non-coherent accumulation is not performed), can be seen from the figure in the simulation conditions, "unfolded zero padding algorithm" in correlation peak at the 500th point is very prominent, can find the correct code phase position. 图5(b)至图5(d),图6(a)至图6(d)分别表示I02, 4, 6, 8, 12, 16, 19,非相干累加次数为1时"双折叠捕获搜索算法"仿真性能。 FIG. 5 (b) to 5 (d), FIG. 6 (a) to 6 (d) respectively, I02, 4, 6, 8, 12, 16, 19, the noncoherent accumulated number of times is 1 "double-folded capture Search algorithm "simulation performance. 从中可以看到X^6时,相关峰已经很突出,能找到正确的码相位。 Which you can see X ^ 6, the correlation peak is very prominent, can find the correct code phase. 图7(a)至图7(c)是M为20,非相干累积次数分别为2, 4, 6情况下"扩展复制重叠捕获搜索算法"的仿真性能,从中可以看出相关峰已经被淹没在噪声中, 不能找到正确的码相位位置;当非相干累积次数为8时,相关峰值较突出,如图7(d)所示。 FIG. 7 (a) to 7 (c) M is 20, the number of non-coherent accumulation are the 2, 4, 6 where "overlapping extended copy acquisition search algorithm" simulation performance, can be seen a correlation peak has been flooded in the noise, you can not find the correct code phase position; when the number of non-coherent accumulation to 8, more prominent correlation peak, as shown in FIG 7 (d) shown in FIG.

在此,若定义搜索时间7= ,,yS,,,fx非相干累积次数,则在相同的待搜索码相 Here, if the definition of search time 7 = ,, yS ,,, fx non-coherent integration times, in the same code phase to be searched

并tr搜索码相位数 Tr search codes and the number of phase

位总数条件下(记待搜索码相位总数为 Under conditions of the total number of bits (the total number of code phases to be searched is referred to

"非折叠补零算法"搜索时间为<formula>formula see original document page 8</formula>"扩展复制重叠捕获搜索算法"搜索时间为<formula>formula see original document page 8</formula>'双折叠捕获搜索算法"搜索时间为<formula>formula see original document page 8</formula> "Unfolded zero-padding algorithm" search time of <formula> formula see original document page 8 </ formula> "extended copy overlap acquisition search algorithm" search time of <formula> formula see original document page 8 </ formula> 'double-folded acquisition search algorithm "search time is <formula> formula see original document page 8 </ formula>

因此"双折叠捕获搜索算法"的搜索时间是"非折叠补零算法"的3.6%,是"扩展复制重叠捕获搜索算法"的17%,具有最快的搜索速度。 Therefore, "double-folded acquisition search algorithm" search time is "non-zero-padding folding algorithm" 3.6%, the "extended copy overlap acquisition search algorithm" is 17%, the fastest search speed.

以上所述实例只是本发明的1个实施例,且不局限于此,在不超过本发明的精神范围的情况下,所做的种种变化实施,都属于本发明的范围。 The above examples are an embodiment of the present invention embodiment, not limited thereto, without exceeding the spirit and scope of the present invention, all the changes made in the embodiment, are within the scope of the present invention.

Claims (2)

  1. 1、长周期扩频码的双折叠捕获搜索方法,其特征在于,针对使用长周期扩频码通信的系统,或是使用扩频码做同步码的通信系统,在接收端依次按以下步骤用一块数字集成电路芯片做扩频码的双折叠同步捕获:步骤(1)在该数字集成电路中,设定该扩频通信中,生成的本地扩频码为Ci,单次积分分组长度为N,扩频码折叠次数为M,接收信号折叠次数为K,扩频捕获功率门限值Po,其中i=0,1....,捕获门限根据所需要的虚警概率、捕获概率来设定。 1, double folding of the long period spreading code acquisition search method, wherein the communication system do preamble spreading code for communication systems using the long period spreading code or use, at the receiving end with the following steps in sequence a digital integrated circuit chip made of double folding the spreading code synchronization acquisition: step (1) in the digital integrated circuit, sets the spread spectrum communication, the generated local spreading code Ci, a single integrated packet length N , the spreading code number of folds is M, the received signal is a folding times K, the spreading capture power threshold value Po, where i = 0,1 ...., false alarm probability of capturing according to the required threshold, set the capture probability set. 设Pfa表示设定的单个待搜索单元的虚警概率,δ2表示噪声方差,A为接收信号幅度,则步骤(2)接收机通过模拟到数字采样器件A/D对接收信号采样后得到序列为Xi,步骤(3)对步骤(2)的采样信号Xi截取长度为KN点的数据,并进行折叠计算,得到序列步骤(4)对步骤(1)的本地生成扩频码为Ci截取长度为MN点的数据,进行折叠计算,得到序列步骤(5)对步骤(3)得到的折叠序列进行FFT变换到频域,得到序列步骤(6)对步骤(4)得到的折叠序列进行FFT变换到频域,得到序列步骤(7)对步骤(5)和步骤(6)得到的序列和共轭相乘,并进行IFFT处理变换回时域,得到序列其中或*表示取复共轭,步骤(8)对步骤(7)得到的序列进行功率检测,并从中找出功率最大值Pmax,“‖‖”表示取模,步骤(9)如果步骤(8)计算得到的功率最大值Pmax小于功率门限值Po,则移动(MK)N点本地伪码重新选取本地扩频码 False alarm probability Pfa arranged to be represented by a single set search unit, Delta] 2 represents the noise variance, A is the amplitude of the received signal, the step (2) a receiver device by an analog to digital sampling A / D to obtain a sequence of received signal samples Xi, step (3) the length of the intercepted signal Xi in step (2) of the sampled data points KN, and folded calculation, the sequence of steps (4) to step (1) of the locally generated spreading code Ci intercept length data MN points, folding calculation, the sequence of steps (5) to step (3) is folded sequence was subjected to FFT into the frequency domain, to obtain sequence of steps (6) to step (4) is folded sequence obtained FFT is to frequency domain sequences obtained in step (7) of step (5) and (6) and the resulting conjugate of a sequence, and transformed back to the time domain the IFFT processing, or to obtain a sequence where * denotes taking the complex conjugate of step ( 8) step (7) obtained sequence power detection, and find out the maximum power Pmax, "‖" denotes a modulo, step (9) If in step (8) the calculated maximum power Pmax is less than the power gate limit Po, the mobile (MK) N-point local pseudo-code reselect the local spreading code 重复步骤(4)至(9),直至利用第f次选取的本地扩频码为基础得到的Pmax大于等于Po,并行搜索码相位单元数由M和K之差决定,在此M不小于K,步骤(10)在第f次选取的扩频码上,用非折叠补零算法进行搜索,对相应的MN点本地伪码相位依次进行搜索,找出与接收信号对齐的本地伪码相位。 Repeating steps (4) to (9), using the f times until the selected local spreading code to obtain greater than or equal Pmax based Po, the number of parallel search code phase difference is determined by means of the K and M, where M is not less than K step (10) in the selection of the spreading code f times, with a non-zero-padding folding algorithm searches for the point MN corresponding to the local code phase sequentially searches to find local code phase of the received signal alignment.
  2. 2、根据权利要求1所述的长周期扩频码的双折叠捕获搜索方法,其特征在于,在步骤(5)中FFT后附加去除多普勒电路模块,利用循环移位的方式,对FFT后的结果进行循环移位,去除接收信号对于发射信号的频率偏移影响。 2, according to claim double folding the long period spreading code acquisition search method of claim 1, wherein, in step (5) after the additional removal of the FFT Doppler circuit module by way of a cyclic shift, the FFT cyclically shifting the result of removing the reception signal for the frequency offset of the signal transmitting impact.
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