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基于m-序列的二元零相关区序列构造新方法*

2014-01-26李明阳彭卫东王晟达

电讯技术 2014年5期
关键词:构造方法交织移位

李明阳,彭卫东,柏 鹏,王晟达

(1.空军工程大学装备管理与安全工程学院,西安710051;2.空军工程大学综合电子信息系统与电子对抗技术研究中心,西安710051;3.空军工程大学航空航天工程学院,西安 710038)

基于m-序列的二元零相关区序列构造新方法*

李明阳1,2,**,彭卫东2,柏 鹏2,王晟达3

(1.空军工程大学装备管理与安全工程学院,西安710051;2.空军工程大学综合电子信息系统与电子对抗技术研究中心,西安710051;3.空军工程大学航空航天工程学院,西安 710038)

基于伪随机序列,提出一种二元零相关区序列构造方法。该方法利用伪随机序列的游程特性,通过在伪随机序列的适当位置进行插值,使生成的序列具有一定长度的零相关区。为了提高序列的丰富性,提出两种扩展方法:一种基于交织技术,通过构造移位序列,使交织序列的周期增大而零相关区不变;另一种方法将零相关区序列与Hadamard矩阵的行向量按位相乘,该方法能够增加零相关区序列数量的同时不改变序列的周期。数值仿真证明了所提方法的有效性。

二元零相关区序列;伪随机序列;交织技术;移位序列;Hadamard矩阵

1 引言

零相关区(Zero Correlation Zone,ZCZ)序列能够有效对抗频率选择性衰落影响,在雷达测距、码分多址通信[1]系统中得到了广泛应用。目前关于ZCZ序列构造方法的研究大多着眼于 ZCZ序列偶[2-3]或者多元 ZCZ序列的构造[4-7]。序列偶的最大相关峰峰值有所下降[2],会降低其抗噪声性能,而多元序列[4]在同步、测距等领域不如二元序列应用广泛。交织方法[8-9]和 Hadamard 矩阵[10-11]已广泛应用于ZCZ序列构造和扩展中。文献[9]利用交织序列和正交矩阵进行相关积运算来构造最佳序列偶集,该方法构造的序列集具有近似最佳性,但是可构造的数量较少。文献[12]中利用交织序列构造3类具有最优自相关值的二元序列,该序列的周期限定为4的倍数。文献[13]构造了一种二元ZCZ序列并将其应用于多输入多输出(Multiple Input Multiple Output,MIMO)系统的信道估计,该序列只具有较好的非周期相关特性,应用范围较为狭窄。文献[14]基于最优序列组和正交矩阵构造了多维二元ZCZ序列,但是最优二元序列和二元正交矩阵数量稀少,构造结果灵活性差。研究表明,除[1,-1,-1,-1]外不存在周期小于548 964 900的完备二元ZCZ序列,关于非完备二元ZCZ序列的研究在数字通信和密码学中都具有重要意义。

本文首先根据伪随机序列的特性,提出一种新的ZCZ序列构造方法,该方法通过在伪随机序列中元素“1”的最大游程末尾插入符号“1”将周期为2k-1的伪随机序列构造成周期为2k且零相关区为k的ZCZ序列。为了克服伪随机序列周期固定、数量较少的缺点,本文提出两种扩展方法:方法1基于交织技术,通过设计移位序列,能够增大序列的周期而不改变序列的零相关区;方法2将ZCZ序列与Hadamard矩阵的行向量按位相乘得到新的ZCZ序列,从而增加序列的数量。最后对文中方法进行了数值仿真,验证了其有效性。

2 基本定义和定理

3 基于伪随机序列的ZCZ序列构造

3.1 ZCZ序列构造方法

3.2 序列周期的扩展方法

3.3 序列数量的扩展方法

4 数值仿真

设置仿真参数,选择周期为7、15、31、63的 m 序列,相应的生成多项式分别为g(z)=z3+z2+1、g(z)=z4+z3+1、g(z)=z5+z3+1、g(z)=z6+z5+1。根据定理1分别构造序列c0~c3,自相关函数如图1所示。

图1 定理1构造序列的自相关函数Fig.1 Auto - correlation of sequences constructed by Theorem 1

由图1可知,4个序列相关函数的仿真结果和定理1的结论一致,且可以看出该ZCZ序列的相关峰值分别为8、16、32、64,而基于伪随机序列构造的序列偶集[17]的相关峰值分别为 4、8、16、32,相关峰值显著下降。

设置仿真参数,选择周期分别为7、15的m序列,生成多项式不变。根据定理2分别构造序列c0~c1,自相关函数如图2所示。

图2 定理2构造序列的自相关函数Fig.2 Auto - correlation of sequences constructed by Theorem 2

由图2可知,定理2的交织方法能够根据周期分别为7、15的伪随机序列生成周期分别为56、240的ZCZ(56,2)和ZCZ(240,3)。该方法虽然不能增大序列零相关区,但是序列周期扩大,且相关峰值幅度也相应增大。

设置仿真参数,选择周期为15的m序列,生成多项式不变。根据定理3构造序列c0~c15,其中前4个序列的自相关函数如图3所示。

图3 数量扩展序列的自相关函数Fig.3 Auto- correlation of volume extended sequences

由图3可知,数量扩展后的前4个序列之间具有不同的自相关函数,也即序列之间移位不等价。图3(a)和(b)中两个序列与图1(b)中序列的零相关区均为3,序列为移位不等价的 ZCZ(16,3);而(c)和(d)中序列的零相关区均为2,两序列为移位不等价的ZCZ(16,2)。所以该扩展方法能够得到多个零相关区不大于原序列且移位不等价的ZCZ序列。

5 结束语

本文提出一种新的零相关区序列构造方法,该方法通过在伪随机序列中插入符号“1”使新序列具有一定的零相关区。文中提出了基于交织技术的序列周期扩展方法和与Hadamard矩阵行向量按位相乘的序列数量扩展方法。交织方法能够生成零相关区不变而周期更长的ZCZ序列;与Hadamard矩阵行向量按位相乘的扩展方法能够生成序列周期和相关峰值保持不变,零相关区不大于原序列的多个序列。这两种方法能够在一定程度上克服由于伪随机序列周期固定、数量少造成的限制,提高了序列的丰富性。已有的ZCZ序列构造方法大多基于交织技术,本文提供一种新的构造思路。新的ZCZ序列在同步、定位中有一定的应用价值。

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A Novel Construction M ethod for Zero Correlation Zone Sequence Based on m-sequence

LI Ming - yang1,2,PENG Wei- dong2,BAI Peng2,WANG Sheng - da3
(1.Equipment Management and Safety Engineering College,Air Force Engineering University,Xi'an 710051,China;2.Synthetic Electronic Information System and Electronic Countermeasure Technology Research Department,Air Force Engineering University,Xi'an 710051,China;3.Aeronautics and Astronautics Engineering College,Air Force Engineering University,Xi'an 710038,China)

Based on pseudo sequence,a binary zero correlation zone(ZCZ)sequence construction method is presented in this paper.By employing the run length characteristic,through interpolating in appropriate location,the sequence is constructed with ZCZ of a certain length.In order to enlarge the richness of the sequences,two extension methods are introduced.One is based on interleaving technique and through designing shift sequence,the sequence constructed by which has increased period and identical ZCZ.The other multiples the ZCZ sequence and row vectors of Hadamard matrix bit by bit to increase the volume but without changing the period of the ZCZ sequences.Numerical simulation validates the effectiveness of the proposed method.

binary zero correlation zone(ZCZ)sequence;pseudo random sequence;interleaving technique;shift sequence;Hadamard matrix

The National Natural Science Foundation of China(No.61174194)

**

wo.lmy@163.com Corresponding author:wo.lmy@163.com

TN911.2

A

1001-893X(2014)05-0559-05

10.3969/j.issn.1001 -893x.2014.05.006

李明阳,彭卫东,柏鹏,等.基于m-序列的二元零相关区序列构造新方法[J].电讯技术,2014,54(5):559-563.[LI Ming-yang,PENG Wei- dong,BAI Peng,et al.A Novel Construction Method for Zero Correlation Zone Sequence Based on m - sequence[J].Telecommunication Engineering,2014,54(5):559 -563.]

2013-12-30;

2014-02-21

date:2013-12-30;Revised date:2014-02-21

国家自然科学基金资助项目(61174194)

李明阳(1985—),男,河北保定人,分别于2008年和2011年获空军工程大学信号与信息处理专业学士学位和硕士学位,现为博士研究生,主要研究方向为扩频通信、扩频序列设计;

LI Ming-yang was born in Baoding,Hebei Province,in 1985.He received the B.S.degreeand the M.S.degree from Air Force Engineering University in 2008 and 2011,respectively.He is currently working toward the Ph.D.degree.His research interests include spread spectrum communication and design of spread spectrum sequence.

Email:wo.lmy@163.com

彭卫东(1968—),男,河北石家庄人,副教授、硕士生导师,主要研究方向为通信工程、数据链技术;

PENG Wei- dong was born in Shijiazhuang,Hebei Province,in 1968.He is now an associate professor and also the instructor of graduate students.His research concerns communication engineering,data link technology.

Email:pengweidong@163.com

柏 鹏(1962—),男,四川成都人,教授、博士生导师,主要研究方向为数据链工程;

BAI Peng was born in Chengdu,Sichuan Province,in 1962.He is now a professor and also the Ph.D.supervisor.His research concerns data link engineering.

Email:Bpeng@163.com

王晟达(1964—),男,河北石家庄人,教授、硕士生导师,主要研究方向为雷达信号处理。

WANG Sheng- da was born in Shijiazhuang,Hebei Province,in 1964.He is now a professor and also the instructor of graduate students.His research concerns data link engineering.

Email:905432530@qq.com

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