WO2018133262A1 - 一种时/频域零相关区二维双极性码的构造方法及系统 - Google Patents

一种时/频域零相关区二维双极性码的构造方法及系统 Download PDF

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WO2018133262A1
WO2018133262A1 PCT/CN2017/084239 CN2017084239W WO2018133262A1 WO 2018133262 A1 WO2018133262 A1 WO 2018133262A1 CN 2017084239 W CN2017084239 W CN 2017084239W WO 2018133262 A1 WO2018133262 A1 WO 2018133262A1
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sequence
frequency domain
time
correlation zone
zero correlation
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吉建华
欧阳攀
王可
徐铭
张志朋
杨淑雯
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Shenzhen University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/004—Orthogonal
    • H04J13/0048—Walsh
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/0055—ZCZ [zero correlation zone]
    • H04J13/007—LAS, i.e. LA, LS and LAS codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/10—Code generation
    • H04J13/12—Generation of orthogonal codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/10—Code generation
    • H04J13/14—Generation of codes with a zero correlation zone
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/005—Optical Code Multiplex
    • H04J14/007—Orthogonal Optical Code Multiplex

Definitions

  • the present invention relates to the field of communication technologies, and in particular, to a method and system for constructing a two-dimensional bipolar code in a zero-correlation region in time/frequency domain.
  • Optical code division multiple access has the characteristics of broadband, security and random instant access, and is one of the best solutions for high-speed local area networks and access networks in the future. According to the degree of freedom, it can be divided into one-dimensional OCDMA system and two-dimensional OCDMA system.
  • the address code of the two-dimensional OCDMA system not only expands in the time domain, but also expands in wavelength, which is called two-dimensional optical orthogonal code.
  • Yin Hongjun et al. constructed a two-dimensional OCFHC/OOC code and a two-dimensional variable weight code with a cross-correlation limit of 1.
  • Li Chuanqi et al. constructed a two-dimensional QPC code with a cross-correlation limit of 1.
  • Lee and Seo use two different one-dimensional OOCs to spread in the time domain and the frequency domain respectively.
  • the constructed two-dimensional optical orthogonal code has a code weight of 3 and a cross-correlation limit of 1.
  • Kwong and Yang use the prime hopping code to control the time domain and the frequency domain.
  • the code length of the constructed two-dimensional optical orthogonal code is prime, and the cross-correlation limit is equal to 1.
  • One-dimensional OOC is a time-domain spreading sequence, and the number of wavelengths is the product of prime numbers.
  • the cross-correlation limit of two-dimensional optical orthogonal codes is equal to 1.
  • E.S. Shivaleela et al. directly constructed a two-dimensional optical orthogonal code using a finite field, and the cross-correlation limit is equal to one.
  • Jen-Hao Tien and Yang et al. constructed a two-dimensional code with cross-correlation limit of 2, which increased the codeword capacity, but increased the multiple access interference between users.
  • S.Kim and K.Yu construct three-dimensional optical orthogonal codes, which are extended in the time domain/frequency domain/space domain (or polarization domain) respectively, and the codeword capacity is greatly increased, but the system implementation is difficult, and related subsequent researches are more less.
  • two-dimensional coherent OCDMA refers to the use of bipolar two-dimensional address codes for spread spectrum coding and optical correlation decoding in a coherent OCDMA system, which has the advantage that the code word capacity is greatly increased.
  • Ye Zhang uses a bipolar m hopping sequence to implement a phase-encoded two-dimensional SSFBG encoder/decoder, a two-dimensional coherent OCDMA system. In two dimensions In a coherent OCDMA system, the codewords between different users are not completely orthogonal, which will lead to multiple access interference.
  • Ji Jianhua et al. constructed a collision-free bipolar hopping code, which can eliminate multiple access interference and beat noise, but the codeword capacity is small (the code weight is equal to the code length), which makes the capacity of the two-dimensional coherent OCDMA system limited.
  • a large-capacity two-dimensional coherent OCDMA system is realized.
  • Ji Jianhua et al. constructed a method and device for forming a two-dimensional optical orthogonal code with zero correlation window, but only suitable for two-dimensional non-coherent OCDMA systems, and the codeword capacity is limited (equal to the effective wavelength of the system).
  • the noise that affects the performance of the entire system mainly includes multiple access interference and beat noise.
  • Multiple access interference is caused by the non-orthogonality of the codewords, which are caused by the squared nature of the photodetector, again depending on the orthogonality of the codewords.
  • the two-dimensional coherent OCDMA system adopts bipolar m hopping sequence, the address code can not be completely orthogonal (the minimum cross-correlation limit is 1), and the cross-correlation property is not ideal, so the system has multiple access interference and beat noise.
  • the multiple access interference and the beat noise become the most important noise, which causes the bit error rate of the two-dimensional coherent OCDMA system to rise sharply, which results in the limitation of the number of access users of the two-dimensional coherent OCDMA.
  • the address codes cannot be completely orthogonal, the two-dimensional coherent OCDMA system has a near-far effect, which requires complicated power control. Therefore, the current two-dimensional coherent OCDMA system is difficult to put into practical use.
  • Ji Ji Jianhua et al. constructed a non-collision zone bipolar hopping code, which can eliminate multiple access interference and beat noise, but the codeword capacity is small (equal to the effective wavelength of the system), making the capacity of the two-dimensional coherent OCDMA system limited. A large-capacity two-dimensional coherent OCDMA system cannot be realized.
  • the invention provides a method for constructing a time/frequency domain zero correlation zone two-dimensional bipolar code, comprising the following steps:
  • m and ZCZ be positive integers, where m represents the number of basic pulses, ZCZ represents the length of the zero correlation zone, and the number of basic pulses is m.
  • the single coincidence sequence is a frequency hopping pseudo random sequence designed for a wireless frequency hopping CDMA system.
  • the number of wavelengths q is an odd integer, defined.
  • the base sequence s of the LA code is a time-spreading pseudo-random sequence
  • the single-coherence sequence is a wavelength hopping pseudo-random sequence
  • the time/frequency domain zero correlation region is formed.
  • the phase of the corresponding chip of the two-dimensional optical orthogonal code of the zero-correlation region in the time/frequency domain is controlled, thereby forming a time/frequency domain.
  • Zero-correlation zone two-dimensional bipolar code according to the polarity of the corresponding chip of the Walsh sequence, the phase of the corresponding chip of the two-dimensional optical orthogonal code of the zero-correlation region in the time/frequency domain is controlled, thereby forming a time/frequency domain.
  • the invention also provides a construction system of a time/frequency domain zero correlation zone two-dimensional bipolar code, comprising:
  • a first constructing module configured to construct a time domain zero correlation zone spreading sequence LA having a zero correlation zone
  • a second construction module for constructing a single coincidence sequence in the frequency domain
  • a first processing module configured to combine a time domain zero correlation zone spreading sequence of a zero correlation zone with a single coincidence sequence of a frequency domain to form a time/frequency domain zero correlation zone two-dimensional optical orthogonal code
  • the second processing module is configured to combine the two-dimensional optical orthogonal code of the time/frequency domain zero correlation zone with the Walsh sequence to form a time/frequency domain zero correlation zone two-dimensional bipolar code.
  • the length ZCZ constructs the base sequence of the LA code, and sets the length of the base sequence to N.
  • the single coincidence sequence is a frequency hopping pseudo-random sequence designed for a wireless frequency hopping CDMA system, and for a given parameter, the number of wavelengths q is an odd integer.
  • the base sequence s of the LA code is a time-spreading pseudo-random sequence
  • the single-coherence sequence is a wavelength hopping pseudo-random sequence, forming a time/frequency domain zero correlation.
  • the phase of the corresponding chip of the two-dimensional optical orthogonal code of the time-correlation region/time domain is controlled, thereby forming a/ Two-dimensional bipolar code in the frequency domain zero correlation zone.
  • the invention has the beneficial effects that: as long as the delay between users is within the zero correlation zone, all codewords are completely orthogonal, which completely eliminates the multiple access interference and beat noise of the two-dimensional coherent OCDMA system, and can also eliminate the second The near-far effect of the dimensional coherent OCDMA system. Therefore, the time/frequency domain zero correlation zone two-dimensional bipolar code constructed by the invention can realize a large-capacity two-dimensional coherent OCDMA system, and is applied to an optical access network, an optical local area network, an optical code label switching network, and an optical fiber sensor network. Wait.
  • Figure 1 is a flow chart of the method of the present invention.
  • the present invention discloses a method for constructing a two-dimensional bipolar code in a time/frequency domain zero correlation zone, which includes the following steps:
  • Step S1 Constructing a time domain zero correlation zone spreading sequence LA having a zero correlation zone
  • Step S2 Constructing a single coincidence sequence of the frequency domain
  • Step S3. Constructing a Walsh sequence
  • Step S4 Combining the time domain zero correlation zone spreading sequence of the zero correlation zone with the single coincidence sequence of the frequency domain to form a time/frequency domain zero correlation zone two-dimensional optical orthogonal code;
  • Step S5. Combining the time/frequency domain zero correlation zone two-dimensional optical orthogonal code with the Walsh sequence, the time/frequency domain zero correlation zone two-dimensional bipolar code is formed.
  • step S1 let m and ZCZ be positive integers, where m represents the number of basic pulses, ZCZ represents the length of the zero correlation zone, and the base sequence of the LA code can be constructed from the basic pulse number m and the zero correlation zone length ZCZ.
  • the distribution positions of the m basic pulses are x1, x2, ..., xm, respectively, and it is assumed that 0 ⁇ x1 ⁇ x2 ⁇ ... ⁇ xm ⁇ N-1.
  • the single coincidence sequence is a frequency hopping pseudo-random sequence designed for a wireless frequency hopping CDMA system.
  • step S3 the second-order Hadamard matrix H2 is:
  • the 2N-order Hadamard matrix H 2N is:
  • step S4 the base sequence s of the LA code is a time-spreading pseudo-random sequence, and the single-coincidence sequence is a wavelength hopping pseudo-random sequence, and the time/frequency domain zero correlation zone two-dimensional optical orthogonal code is constructed.
  • step S5 according to the polarity of the corresponding chip of the Walsh sequence (ie +1 or -1), the phase of the corresponding chip of the two-dimensional optical orthogonal code of the time-correlation region/time domain is controlled, thereby forming a time/frequency domain zero.
  • m ⁇ ⁇ 16,17,18,20,19,22,23,21 ⁇
  • Sequence 1 3,8,1,5,2,10,4,0 Sequence 2 4,9,2,6,3,11,5,1 Sequence 3 5,10,3,7,4,12,6,2 Sequence 4 6,11,4,8,5,0,7,3 Sequence 5 7,12,5,9,6,1,8,4 Sequence 6 8,0,6,10,7,2,9,5 Sequence 7 9,1,7,11,8,3,10,6 Sequence 8 10,2,8,12,9,4,11,7 Sequence 9 11,3,9,0,10,5,12,8 Sequence 10 12,4,10,1,11,6,0,9 Sequence 11 0,5,11,2,12,7,1,10 Sequence 12 1,6,12,3,0,8,2,11
  • step S3 a Walsh sequence of length 8 is constructed with a codeword capacity of 8, i.e., each row of the matrix represents a Walsh code.
  • a two-dimensional optical orthogonal code of the time/frequency domain zero correlation region is constructed from the above LA base sequence s and the single coincidence sequence in Table 1, as shown in Table 2, the code length of the two-dimensional code is 156, The length of the zero correlation zone is 16, the code weight is 8, the effective wavelength is 13, the codeword capacity is 13, the autocorrelation limit is 0, and the cross correlation limit is 1, which can be expressed as (156,16,8,0). ,1).
  • step S5 according to the polarity of the corresponding chip of the Walsh sequence (ie +1 or -1), the phase of the corresponding chip of the two-dimensional optical orthogonal code of the time-correlation region/time domain is controlled, thereby forming a time/frequency domain zero.
  • Correlated 2D bipolar code Taking C13 as an example, each Walsh code is combined with C13 (controls the phase of the corresponding chip) to form two time/frequency domain zero correlation zone two-dimensional bipolar codes, ie
  • any one of the time/frequency domain zero correlation zone two-dimensional optical orthogonal codes in Table 2 can be combined with each Walsh code (control the phase of the corresponding chip), which can constitute 104 time/frequency domain zeros in total.
  • the two-dimensional bipolar code of the relevant area (the codeword capacity of the non-collision zone bipolar hopping code is only 13, and the codeword capacity of the two-dimensional optical orthogonal code of the zero correlation window is only 13). Therefore.
  • the large-capacity time/frequency domain zero correlation zone two-dimensional bipolar code constructed by the invention can realize a large-capacity two-dimensional coherent OCDMA system, and is applied to an optical access network, an optical local area network, an optical code label switching network, and a fiber sensor network. Wait.
  • the invention also discloses a construction system of a time/frequency domain zero correlation zone two-dimensional bipolar code, comprising:
  • a first constructing module configured to construct a time domain zero correlation zone spreading sequence LA having a zero correlation zone
  • a second construction module for constructing a single coincidence sequence in the frequency domain
  • a first processing module configured to combine a time domain zero correlation zone spreading sequence of a zero correlation zone with a single coincidence sequence of a frequency domain to form a time/frequency domain zero correlation zone two-dimensional optical orthogonal code
  • the second processing module is configured to combine the two-dimensional optical orthogonal code of the time/frequency domain zero correlation zone with the Walsh sequence to form a time/frequency domain zero correlation zone two-dimensional bipolar code.
  • m and ZCZ be positive integers, where m represents the number of basic pulses, ZCZ represents the length of the zero correlation zone, and the LA code is constructed from the basic pulse number m and the zero correlation zone length ZCZ.
  • the pulse interval assumes that the distribution positions of the m basic pulses are x1, x2, ..., xm, respectively, and it is assumed that 0 ⁇ x1 ⁇ x2 ⁇ ... ⁇ xm ⁇ N-1.
  • the single coincidence sequence is a frequency hopping pseudo-random sequence designed for a wireless frequency hopping CDMA system.
  • the number of wavelengths q is an odd integer, and the length of the hopping sequence is defined.
  • the base sequence s of the LA code is a time-spreading pseudo-random sequence
  • the single-coincidence sequence is a wavelength hopping pseudo-random sequence
  • the two-dimensional optical orthogonal code of the zero-correlation region in the time/frequency domain is formed.
  • the phase of the corresponding chip of the two-dimensional optical orthogonal code in the zero-correlation region of the time/frequency domain is controlled, thereby forming a time/frequency domain zero correlation region two-dimensionally.
  • Bipolar code according to the polarity of the corresponding chip of the Walsh sequence, the phase of the corresponding chip of the two-dimensional optical orthogonal code in the zero-correlation region of the time/frequency domain is controlled, thereby forming a time/frequency domain zero correlation region two-dimensionally.
  • the method and system for constructing a time/frequency domain zero correlation region two-dimensional bipolar code according to the present invention is different from the traditional two-dimensional optical orthogonal code and different from the traditional one-dimensional time domain zero correlation region spreading sequence. Moreover, the code word capacity is much larger than the existing collision-free area bipolar hopping code. In the present invention, as long as the delay between users is within the zero correlation region, all codewords are completely orthogonal, which will completely eliminate the multiple access interference and beat noise of the two-dimensional coherent OCDMA system, and can also eliminate the near-far effect of the two-dimensional coherent OCDMA system. .
  • the time/frequency domain zero correlation zone two-dimensional bipolar code constructed by the invention can realize a large-capacity two-dimensional coherent OCDMA system, and is applied to an optical access network, an optical local area network, an optical code label switching network, and an optical fiber sensor network. Wait.

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Abstract

本发明提供了一种时/频域零相关区二维双极性码的构造方法及系统，该构造方法包括：A.构造具有零相关区的时域零相关区扩频序列LA；B.构造频域的单重合序列；C.构造Walsh序列；D.将零相关区的时域零相关区扩频序列与频域的单重合序列相结合，构成时/频域零相关区二维光正交码；E.将时/频域零相关区二维光正交码与Walsh序列结合，则构成时/频域零相关区二维双极性码。本发明的有益效果是：本发明完全消除二维相干OCDMA系统的多址干扰和差拍噪声，也可以消除二维相干OCDMA系统的远近效应，因此，本发明可实现大容量的二维相干OCDMA系统，应用于光接入网、光局域网、光码标记交换网络、光纤传感器网等。

Description

一种时/频域零相关区二维双极性码的构造方法及系统 技术领域
本发明涉及通讯技术领域，尤其涉及一种时/频域零相关区二维双极性码的构造方法及系统。
背景技术
光码分多址(OCDMA)具有宽带、安全和随机即时接入等特点，是未来高速局域网和接入网的最佳方案之一。按自由度分可以分为一维OCDMA系统和二维OCDMA系统，二维OCDMA系统的地址码不仅在时域上扩展，同时还在波长上扩展，称为二维光正交码。
目前，国内外的许多学者已构造了多类二维OCDMA地址码。基于素数码(Prime code),Tancevski.L等构造了PC/PC和EQC/PC，PC/PC码的自相关限为0，互相关限为1，EQC/PC的自相关限为0，互相关限为2。万生鹏等基于素数码和光正交码，构造了PC/OOC码，它的自相关限为0，互相关限为1。周秀丽等基于RS码，构造了多倍长多波长RS码，它的自相关限为0，互相关限为1。殷洪玺等构造了二维OCFHC/OOC码和二维变重码，互相关限为1。李传起等构造了二维QPC码，互相关限为1。Lee和Seo利用两个不同的一维OOC分别在时域和频域扩展，构造的二维光正交码的码重为3，互相关限为1。Kwong和Yang利用素数跳频码控制时域和频域，构造的二维光正交码的码长为素数，互相关限等于1。Kwong等采用素数码及其循环序列为频域扩频序列，一维OOC为时域扩频序列，波长数为素数之乘积，二维光正交码的互相关限等于1。E.S.Shivaleela等利用有限域直接构造了二维光正交码，互相关限等于1。Jen-Hao Tien和Yang等构造了互相关限为2的二维码，增加了码字容量，但增加了用户之间的多址干扰。S.Kim和K.Yu构造了三维光正交码，分别在时域/频域/空域(或偏振域)进行扩展，其码字容量大大增加，但系统实现难度大，相关的后续研究较少。
另一方面，随着光编解码器技术的发展，传统的二维非相干OCDMA系统向二维相干OCDMA系统演进。所谓二维相干OCDMA，是指在相干OCDMA系统中，采用双极性的二维地址码进行扩频编码和光相关解码，其优点是码字容量大大增加。Ye Zhang采用双极性的m跳频序列，实现了相位编码的二维SSFBG编/解码器，即二维相干OCDMA系统。在二维 相干OCDMA系统中，不同用户之间的码字不完全正交将导致多址干扰，目标信号和干扰信号经过光电检测器时将导致差拍噪声，而差拍噪声远远大于多址干扰，成为二维相干OCDMA系统最主要的噪声。吉建华等构造了无碰撞区双极性跳频码，可以消除多址干扰和差拍噪声，但码字容量较小(码重等于码长)，使二维相干OCDMA系统容量受限，无法实现大容量的二维相干OCDMA系统。吉建华等构造了一种具有零相关窗的二维光正交码的形成方法及装置，但只适合与二维非相干OCDMA系统，而且码字容量有限(等于系统的有效波长数)。
在二维相干OCDMA系统中，影响整个系统性能的噪声主要包括多址干扰和差拍噪声。多址干扰是由码字的不正交引起的，差拍噪声是由光检测器的平方特性引起的，这同样取决于码字的正交性。目前，二维相干OCDMA系统采用双极性的m跳频序列，地址码不能完全正交(互相关限最小为1)，互相关特性不理想，因此系统存在多址干扰和差拍噪声。尤其当并发用户数较多时，多址干扰和差拍噪声成为最主要的噪声，使二维相干OCDMA系统的误码率急剧上升，从而导致二维相干OCDMA的接入用户数受到限制。同时，由于地址码不能完全正交，二维相干OCDMA系统存在远近效应，这需要复杂的功率控制。因此，目前二维相干OCDMA系统难以实用化。
吉建华等构造了无碰撞区双极性跳频码，可以消除多址干扰和差拍噪声，但码字容量较小(等于系统的有效波长数)，使二维相干OCDMA系统容量受限，无法实现大容量的二维相干OCDMA系统。
发明内容
本发明提供了一种时/频域零相关区二维双极性码的构造方法，包括如下步骤：
A.构造具有零相关区的时域零相关区扩频序列LA；
B.构造频域的单重合序列；
C.构造Walsh序列；
D.将零相关区的时域零相关区扩频序列与频域的单重合序列相结合，构成时/频域零相关区二维光正交码；
E.将时/频域零相关区二维光正交码与Walsh序列结合，则构成时/频域零相关区二维双极性码。
作为本发明的进一步改进，在所述步骤A中，设m、ZCZ为正整数，其中m代表基本脉冲的个数，ZCZ代表零相关区的长度，由基本脉冲数m 和零相关区长度ZCZ构造出LA码的基序列，并设该基序列的长度为N，用s＝{s1，s2，…，sN}表示基序列，用{δi，i＝1，2，…，m}表示基序列中对应的基本脉冲间隔，假设m个基本脉冲的分布位置分别为x1，x2，…，xm，并且假设0≤x1≤x2≤…≤xm≤N-1。
作为本发明的进一步改进，在所述步骤B中，单重合序列是一种为无线跳频CDMA系统设计的跳频伪随机序列，对于给定的参数，设波长数目q为一个奇整数，定义跳频序列的长度为L＝m＝q－2d－1，如果q为一个偶整数，则定义L＝q－2d－2，其中m与步骤A中的意义一样，d为任意两个相邻“chip”波长的最小间隔，则可以构成q个长为L的单重合序列集，用A＝{a1，a2，…，aq}表示该序列集，其中
Figure PCTCN2017084239-appb-000001
其中i＝1，2，…，q。
作为本发明的进一步改进，在所述步骤D中，以LA码的基序列s为时间扩频伪随机序列，以单重合序列为波长跳频伪随机序列，构成时/频域零相关区二维光正交码。
作为本发明的进一步改进，在所述步骤E中，根据Walsh序列相应码片的极性，控制时/频域零相关区二维光正交码相应码片的相位，从而构成时/频域零相关区二维双极性码。
本发明还提供了一种时/频域零相关区二维双极性码的构造系统，包括：
第一构造模块，用于构造具有零相关区的时域零相关区扩频序列LA；
第二构造模块，用于构造频域的单重合序列；
第三构造模块，用于构造Walsh序列；
第一处理模块，用于将零相关区的时域零相关区扩频序列与频域的单重合序列相结合，构成时/频域零相关区二维光正交码；
第二处理模块，用于将时/频域零相关区二维光正交码与Walsh序列结合，则构成时/频域零相关区二维双极性码。
作为本发明的进一步改进，在所述第一构造模块中，设m、ZCZ为正整数，其中m代表基本脉冲的个数，ZCZ代表零相关区的长度，由基本脉冲数m和零相关区长度ZCZ构造出LA码的基序列，并设该基序列的长度为N，用s＝{s1，s2，…，sN}表示基序列，用{δi，i＝1，2，…，m}表示基序列中对应的基本脉冲间隔，假设m个基本脉冲的分布位置分别为x1，x2，…，xm，并且假设0≤x1≤x2≤…≤xm≤N-1。
作为本发明的进一步改进，在所述第二构造模块中，单重合序列是一 种为无线跳频CDMA系统设计的跳频伪随机序列，对于给定的参数，设波长数目q为一个奇整数，定义跳频序列的长度为L＝m＝q－2d－1，如果q为一个偶整数，则定义L＝q－2d－2，其中m与第一构造模块中的意义一样，d为任意两个相邻“chip”波长的最小间隔，则可以构成q个长为L的单重合序列集，用A＝{a1，a2，…，aq}表示该序列集，其中
Figure PCTCN2017084239-appb-000002
其中i＝1，2，…，q。
作为本发明的进一步改进，在所述第一处理模块中，以LA码的基序列s为时间扩频伪随机序列，以单重合序列为波长跳频伪随机序列，构成时/频域零相关区二维光正交码。
作为本发明的进一步改进，在所述第二处理模块中，根据Walsh序列相应码片的极性，控制时/频域零相关区二维光正交码相应码片的相位，从而构成时/频域零相关区二维双极性码。
本发明的有益效果是：本发明只要用户之间的延迟在零相关区内，所有码字完全正交，这将完全消除二维相干OCDMA系统的多址干扰和差拍噪声，也可以消除二维相干OCDMA系统的远近效应。因此，本发明构造的时/频域零相关区二维双极性码，可实现大容量的二维相干OCDMA系统，应用于光接入网、光局域网、光码标记交换网络、光纤传感器网等。
附图说明
图1是本发明的方法流程图。
具体实施方式
如图1所示，本发明公开了一种时/频域零相关区二维双极性码的构造方法，包括如下步骤：
步骤S1.构造具有零相关区的时域零相关区扩频序列LA；
步骤S2.构造频域的单重合序列；
步骤S3.构造Walsh序列；
步骤S4.将零相关区的时域零相关区扩频序列与频域的单重合序列相结合，构成时/频域零相关区二维光正交码；
步骤S5.将时/频域零相关区二维光正交码与Walsh序列结合，则构成时/频域零相关区二维双极性码。
在步骤S1中，设m，ZCZ为正整数，其中m代表基本脉冲的个数，ZCZ代表零相关区的长度，由基本脉冲数m和零相关区长度ZCZ就可以构造出LA码的基序列(也可通过算法搜索)，并设该基序列的长度为N，用s＝{s1，s2，…，sN}表示基序列，用{δi，i＝1，2，…，m}表示基序列中 对应的基本脉冲间隔，假设m个基本脉冲的分布位置分别为x1，x2，…，xm，并且假设0≤x1≤x2≤…≤xm≤N-1。
在步骤S2中，单重合序列是一种为无线跳频CDMA系统设计的跳频伪随机序列，该序列的特点是自相关限为0，互相关限为1。构造方法：对于给定的参数，设波长数目q为一个奇整数，定义跳频序列的长度为L＝m＝q－2d－1(如果q为一个偶整数，则定义L＝q－2d－2)，其中m与步骤S1中的意义一样，d为任意两个相邻“chip”波长的最小间隔，则可以构成q个长为L的单重合序列集，用A＝{a1，a2，…，aq}表示该序列集，其中
Figure PCTCN2017084239-appb-000003
其中i＝1，2，…，q。
在步骤S3中，2阶Hadamard矩阵H2为:
Figure PCTCN2017084239-appb-000004
2N阶Hadamard矩阵H2N为:
Figure PCTCN2017084239-appb-000005
在步骤S4中，以LA码的基序列s为时间扩频伪随机序列，以单重合序列为波长跳频伪随机序列，构成时/频域零相关区二维光正交码。对单重合序列集A扩充，生成长度为N(使得该序列与LA基序列的长度一样)的序列集H＝{h1，h2，…，hq},其中
Figure PCTCN2017084239-appb-000006
Figure PCTCN2017084239-appb-000007
基序列s与序列集H＝{h1，h2，…，hq}中的每个序列按位相乘，则可得到的序列集C＝{c1，c2，…，cq}，其中
Figure PCTCN2017084239-appb-000008
其中i＝1，2，…，q，序列集C就是具有零相关区的时/频域零相关区二维光正交码，码长为N，零相关区长度为ZCZ，波长数为q，码重为m＝L，码字容量为q，自相关限为0，互相关限为1，用参数表示为(N，ZCZ，m，0，1)。
在步骤S5中，根据Walsh序列相应码片的极性(即+1或-1)，控制时/频域零相关区二维光正交码相应码片的相位，从而构成时/频域零相关区二维双极性码。码字容量为q*m，码长为N，零相关区长度为ZCZ，波长 数为q，码重为m＝L，自相关限为0，互相关限为1。
具体构造如下：
在步骤S1中，设构造LA基序列的基本脉冲数为m＝8，零相关区的长度为ZCZ＝16，可以得到基序列中对应的基本脉冲间隔{δi，i＝1，2，…，m}＝{16，17，18，20，19，22，23，21}，总长度为N＝156的基序列为：
Figure PCTCN2017084239-appb-000009
在步骤S2中，设构造单重合序列的波长数目(也就是有效波长数)q＝13，任意两个相邻波长的最小间隔为d＝2，则可以构成序列长度为L＝q－2d－1＝8的单重合序列为(3，5，6，4，10，8，7，9)，该产生序列是通过计算机搜索的方法得到的，由产生序列构造出的单重合序列如下表1所示：
序列1 3，8，1，5，2，10，4，0
序列2 4，9，2，6，3，11，5，1
序列3 5，10，3，7，4，12，6，2
序列4 6，11，4，8，5，0，7，3
序列5 7，12，5，9，6，1，8，4
序列6 8，0，6，10，7，2，9，5
序列7 9，1，7，11，8，3，10，6
序列8 10，2，8，12，9，4，11，7
序列9 11，3，9，0，10，5，12，8
序列10 12，4，10，1，11，6，0，9
序列11 0，5，11，2，12，7，1，10
序列12 1，6，12，3，0，8，2，11
序列13 2，7，0，4，1，9，3，12
在步骤S3中，构造长度为8的Walsh序列，码字容量为8，即矩阵的每一行代表一个Walsh码。
Figure PCTCN2017084239-appb-000010
Figure PCTCN2017084239-appb-000011
在步骤S4中，由以上LA基序列s和表1中的单重合序列构造时/频域零相关区二维光正交码，如表2所示，该二维码的码长为156，零相关区长度为16，码重为8，有效波长数为13，码字容量为13，自相关限为0，互相关限为1，用参数表示可以表示为(156，16，8，0，1)。
Figure PCTCN2017084239-appb-000012
Figure PCTCN2017084239-appb-000013
表2
在步骤S5中，根据Walsh序列相应码片的极性(即+1或-1)，控制时/频域零相关区二维光正交码相应码片的相位，从而构成时/频域零相关区二维双极性码。以C13为例，每个Walsh码与C13结合(控制相应码片的相位)，可以构成8个时/频域零相关区二维双极性码，即
Figure PCTCN2017084239-appb-000014
Figure PCTCN2017084239-appb-000015
类似地，表2中的任意一个时/频域零相关区二维光正交码，都可以与每个Walsh码结合(控制相应码片的相位)，总共可以构成104个时/频域零相关区二维双极性码(无碰撞区双极性跳频码的码字容量只有13，零相关窗的二维光正交码的码字容量只有13)。因此。本发明构造的大容量时/频域零相关区二维双极性码，可实现大容量的二维相干OCDMA系统，应用于光接入网、光局域网、光码标记交换网络、光纤传感器网等。
本发明还公开了一种时/频域零相关区二维双极性码的构造系统，包括：
第一构造模块，用于构造具有零相关区的时域零相关区扩频序列LA；
第二构造模块，用于构造频域的单重合序列；
第三构造模块，用于构造Walsh序列；
第一处理模块，用于将零相关区的时域零相关区扩频序列与频域的单重合序列相结合，构成时/频域零相关区二维光正交码；
第二处理模块，用于将时/频域零相关区二维光正交码与Walsh序列结合，则构成时/频域零相关区二维双极性码。
在所述第一构造模块中，设m、ZCZ为正整数，其中m代表基本脉冲的个数，ZCZ代表零相关区的长度，由基本脉冲数m和零相关区长度ZCZ构造出LA码的基序列，并设该基序列的长度为N，用s＝{s1，s2，…，sN}表示基序列，用{δi，i＝1，2，…，m}表示基序列中对应的基本脉冲间隔，假设m个基本脉冲的分布位置分别为x1，x2，…，xm，并且假设0≤x1≤x2≤…≤xm≤N-1。
在所述第二构造模块中，单重合序列是一种为无线跳频CDMA系统设计的跳频伪随机序列，对于给定的参数，设波长数目q为一个奇整数，定 义跳频序列的长度为L＝m＝q－2d－1，如果q为一个偶整数，则定义L＝q－2d－2，其中m与第一构造模块中的意义一样，d为任意两个相邻“chip”波长的最小间隔，则可以构成q个长为L的单重合序列集，用A＝{a1，a2，…，aq}表示该序列集，其中
Figure PCTCN2017084239-appb-000016
其中i＝1，2，…，q。
在所述第一处理模块中，以LA码的基序列s为时间扩频伪随机序列，以单重合序列为波长跳频伪随机序列，构成时/频域零相关区二维光正交码。
在所述第二处理模块中，根据Walsh序列相应码片的极性，控制时/频域零相关区二维光正交码相应码片的相位，从而构成时/频域零相关区二维双极性码。
本发明的时/频域零相关区二维双极性码的构造方法及系统，既不同于传统的二维光正交码，又不同于传统的一维时域零相关区扩频序列，而且码字容量远远大于已有的无碰撞区双极性跳频码。本发明只要用户之间的延迟在零相关区内，所有码字完全正交，这将完全消除二维相干OCDMA系统的多址干扰和差拍噪声，也可以消除二维相干OCDMA系统的远近效应。因此，本发明构造的时/频域零相关区二维双极性码，可实现大容量的二维相干OCDMA系统，应用于光接入网、光局域网、光码标记交换网络、光纤传感器网等。
以上内容是结合具体的优选实施方式对本发明所作的进一步详细说明，不能认定本发明的具体实施只局限于这些说明。对于本发明所属技术领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干简单推演或替换，都应当视为属于本发明的保护范围。

Claims (10)

  1. 一种时/频域零相关区二维双极性码的构造方法，其特征在于，包括如下步骤：
    A.构造具有零相关区的时域零相关区扩频序列LA；
    B.构造频域的单重合序列；
    C.构造Walsh序列；
    D.将零相关区的时域零相关区扩频序列与频域的单重合序列相结合，构成时/频域零相关区二维光正交码；
    E.将时/频域零相关区二维光正交码与Walsh序列结合，则构成时/频域零相关区二维双极性码。
  2. 根据权利要求1所述的构造方法，其特征在于，在所述步骤A中，设m、ZCZ为正整数，其中m代表基本脉冲的个数，ZCZ代表零相关区的长度，由基本脉冲数m和零相关区长度ZCZ构造出LA码的基序列，并设该基序列的长度为N，用s＝{s1，s2，…，sN}表示基序列，用{δi，i＝1，2，…，m}表示基序列中对应的基本脉冲间隔，假设m个基本脉冲的分布位置分别为x1，x2，…，xm，并且假设0≤x1≤x2≤…≤xm≤N-1。
  3. 根据权利要求2所述的构造方法，其特征在于，在所述步骤B中，单重合序列是一种为无线跳频CDMA系统设计的跳频伪随机序列，对于给定的参数，设波长数目q为一个奇整数，定义跳频序列的长度为L＝m＝q－2d－1，如果q为一个偶整数，则定义L＝q－2d－2，其中m与步骤A中的意义一样，d为任意两个相邻“chip”波长的最小间隔，则可以构成q个长为L的单重合序列集，用A＝{a1，a2，…，aq}表示该序列集，其中
    Figure PCTCN2017084239-appb-100001
    其中i＝1，2，…，q。
  4. 根据权利要求3所述的构造方法，其特征在于，在所述步骤D中，以LA码的基序列s为时间扩频伪随机序列，以单重合序列为波长跳频伪随机序列，构成时/频域零相关区二维光正交码。
  5. 根据权利要求4所述的构造方法，其特征在于，在所述步骤E中，根据Walsh序列相应码片的极性，控制时/频域零相关区二维光正交码相应码片的相位，从而构成时/频域零相关区二维双极性码。
  6. 一种时/频域零相关区二维双极性码的构造系统，其特征在于，包括：
    第一构造模块，用于构造具有零相关区的时域零相关区扩频序列LA；
    第二构造模块，用于构造频域的单重合序列；
    第三构造模块，用于构造Walsh序列；
    第一处理模块，用于将零相关区的时域零相关区扩频序列与频域的单重合序列相结合，构成时/频域零相关区二维光正交码；
    第二处理模块，用于将时/频域零相关区二维光正交码与Walsh序列结合，则构成时/频域零相关区二维双极性码。
  7. 根据权利要求6所述的构造系统，其特征在于，在所述第一构造模块中，设m、ZCZ为正整数，其中m代表基本脉冲的个数，ZCZ代表零相关区的长度，由基本脉冲数m和零相关区长度ZCZ构造出LA码的基序列，并设该基序列的长度为N，用s＝{s1，s2，…，sN}表示基序列，用{δi，i＝1，2，…，m}表示基序列中对应的基本脉冲间隔，假设m个基本脉冲的分布位置分别为x1，x2，…，xm，并且假设0≤x1≤x2≤…≤xm≤N-1。
  8. 根据权利要求7所述的构造系统，其特征在于，在所述第二构造模块中，单重合序列是一种为无线跳频CDMA系统设计的跳频伪随机序列，对于给定的参数，设波长数目q为一个奇整数，定义跳频序列的长度为L＝m＝q－2d－1，如果q为一个偶整数，则定义L＝q－2d－2，其中m与第一构造模块中的意义一样，d为任意两个相邻“chip”波长的最小间隔，则可以构成q个长为L的单重合序列集，用A＝{a1，a2，…，aq}表示该序列集，其中
    Figure PCTCN2017084239-appb-100002
    其中i＝1，2，…，q。
  9. 根据权利要求8所述的构造系统，其特征在于，在所述第一处理模块中，以LA码的基序列s为时间扩频伪随机序列，以单重合序列为波长跳频伪随机序列，构成时/频域零相关区二维光正交码。
  10. 根据权利要求9所述的构造系统，其特征在于，在所述第二处理模块中，根据Walsh序列相应码片的极性，控制时/频域零相关区二维光正交码相应码片的相位，从而构成时/频域零相关区二维双极性码。
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