一类II型偶长Z-互补序列对的构造
Construction of Even-Length Type II Z-Complementary Pairs
摘要: 文章以二进制互补对的核为基础,利用Turyn构造法得到一种长度为 N = 2 α 10 β 26 γ ( α , β , γ 为非负整数)的Golay互补对(Golay Complementary Pair, GCP),在此基础上利用级联和删除函数得到长度为II型 2 N 2 的偶长Z-互补对,并且它们非周期相关函数和在零相关区外的幅值为4,丰富了II型偶长Z-互补序列对的数量。与已知传统的序列构造方法相比,文章提出了一种新的构造方法。
Abstract: Based on the kernel of binary complementary pairs, a Golay Complementary Pair (GCP) with a sequence length of N = 2 α 10 β 26 γ (and α , β , γ are non-negative integers) was constructed by using Turyn Construction. On this basis, the Deletion Function and Cascading were used to obtain the Type II EB-ZCP with a length of 2 N 2 , and their aperiodic correlation functions and amplitudes outside the zero-correlation region were 4, which enriches the number of Type II EB-ZCP. Compared with the known traditional sequence construction methods, a new construction method is proposed.
文章引用:何颖. 一类II型偶长Z-互补序列对的构造[J]. 应用数学进展, 2025, 14(2): 62-68. https://doi.org/10.12677/aam.2025.142052

1. 引言

零相关区互补序列在通信系统[1] [2]、雷达[3]、信道估计[4]等领域有着重要应用。特别地,II型Z-互补对(Z-Complementary Pair, ZCP)在宽带无线通信系统中可解决最小干扰信号延迟的抑制问题。互补对又称格雷互补对[5] (Golay Complementary Pair, GCP),在序列设计中已经被广泛应用。因此,ZCPs对于无线通信系统的研究具有十分重要的意义。

2007年,Fan [6]等人首次提出了Z-互补对(Z-Complementary Pairs, ZCPs)的概念。2021年,Gu等人[7]通过Turyn构造了长度为3N和14N的Z-最优II型偶长ZCP。同年,文献[7]通过迭代法还构造了一类有新长度的II型偶长ZCP,其参数为 ( 2 k N + 2 k 1 , 2 k N + 2 k 1 N ( N Z , k 2 ) ) 2 k N + 2 k 1 N ( N Z , k 2 ) 。2021年,Kumar等人[8]通过多变量函数,构造了一类II型偶长ZCP,其长度为 ( 2 m P , 2 m P + 1 P ( m , P 1 ) ) ,此构造可以满足任意II型偶长ZCP的长度。2022年,Peng等人[9]基于布尔函数,构建了长度为 ( 2 m + 3 + 2 m + 2 + 2 m + 1 , 2 m + 3 + 2 m + 2 ) 的II型偶长ZCP,其相关区比率6/7。2023年,Zeng等人[10]通过映射和交织的方法得到一类长度为 2 × 2 α 10 β 26 γ 的Z-最优II型偶长ZCP。2023年,陈等人[11]通过迭代技术,构造了长度分别为 ( 2 k + 2 N , ( 2 k + 2 1 ) N ) ( 2 N + 2 , 3 N 2 + 2 ) ( 2 k + 2 N + 2 k + 1 , 2 k + 2 N + 2 k + 1 N 2 ) 的II型偶长ZCP,且零相关区外相关函数值较小。2023年,陈等人[12]通过交织法构造了长度为 ( ( 2 k + 1 ) N , ( 2 k + 1 ) N k ) 的II型偶长ZCP,其零相关区宽度可以接近或达到II型偶长二进制Z-互补对的理论上界。2023年,陈等人通过插入法构造了长度为 ( 2 N + 2 , 3 2 N + 2 ) 的II型偶长ZCP。综上所述,构造出长度更为灵活的II型EB-ZCPs具有重要的意义和价值。

本文结构如下:第二节介绍了一些需要用到的符号与定义;第三节给出了II型偶长Z-互补序列对的构造,证明与实例;第四节对本文进行了总结。

2. 预备知识

本文中的一些符号表示如下:

+和−分别表示+1和−1;

a b 表示 a b 的克罗内克积;

a | | b 表示 a b 的级联。

定义1 对于一个长度为N的二进制序列对 ( a , b ) ,定义非周期互相关函数(ACCF)

ρ a , b ( τ ) = i = 0 N 1 τ a i b i + τ ,    0 τ N 1

a = b   ρ a , b ( τ ) 被称之为非周期自相关函数(AACF),记为 ρ a ( τ )

定义2 a b 为两条长度为N的二进制序列,若对任意 1 τ N 1 ,且序列对 ( a , b ) 满足

ρ a ( τ ) + ρ b ( τ ) = 0 ,

则称序列对 ( a , b ) 为格雷互补对(GCP)。

引理1 如果 ( a , b ) 是长度为N、ZCZ宽度为Z的II型EB-ZCP,则

Z N 1

定义3 如果上式可以取等号,则称 ( a , b ) 达到Z-最优,即II型EB-ZCP的ZCZ宽度的理论上界为 Z = N 1

引理2 [13]

( a 0 ; b 0 ) = K 2

( a i ; b i ) = T u r y n ( A 0 , ( a i 1 ; b i 1 ) ) ,   A 0 { K 2 , K 10 , K 26 } ,

( a ; b ) = ( a i ; b i ) 是长度为 N = 2 α 10 β 26 γ ( α 1 , β , γ 0 且为整数的GCP),并且 ( a i ; b i ) 该序列对的前 N / 2 项每列都具有相同的符号。

3. 构造

定理1 设序列对 ( a , b ) 是由引理2生成的长度为N的GCP,构造序列对 ( c , d ) c = ( a b ) d = ( b a ) ( r 1 , r 2 ) = ( 0 , 2 N 1 ) ( r 1 , r 2 ) = ( N 2 1 , N 2 ) e υ ( c , r 1 , r 2 ) f υ ( d , r 1 , r 2 ) ,其中 υ ( ) 是删除函数。则序列对 ( e , f ) 是II型偶长Z-互补序列对,参数是 ( 2 N 2 , 3 2 N 1 ) ,并且在零相关区外的幅值为4。

证明 令 a = ( a 0 , a 1 , , a N 1 ) b = ( b 0 , b 1 , , b N 1 ) 是一个长度为 N = 2 α 10 β 26 γ 的GCP,并且它满足 α 1 β , γ 0 α , β , γ 为非负整数。根据删除函数的定义:

1) 当 r 1 = 0 , r 2 = 2 N 1 ,可以得到 ( e , f ) ,即

  e = ( e 0 , e 1 , , e N 1 ) = ( a 1 , a 2 , , a N 1 , b N 1 , b N 2 , , b 1 ) f = ( f 0 , f 1 , , f N 1 ) = ( b 1 , b 2 , , b N 1 , a N 1 , a N 2 , , a 1 )

根据 τ 取值范围分下面三种情形讨论 | ρ e ( τ ) + ρ f ( τ ) |

情形1:当 N 1 τ 2 N 3 时,

ρ e ( τ ) = i = 1 N 1 a i b 2 N τ i 1 ρ f ( τ ) = i = 1 N 1 b i ( a 2 N τ i 1 )

| ρ e ( τ ) + ρ f ( τ ) | = | i = 1 N 1 a i b 2 N τ i 1 i = 1 N 1 b i ( a 2 N τ i 1 ) | = 0

情形2:当 N 2 τ N 2 时,

ρ e ( τ ) = i = 1 N τ 1 a i a i + τ + i = N τ N 1 a i b 2 N τ i 1 + i = 1 N τ 1 b i b i + τ ρ f ( τ ) = i = 1 N τ 1 b i b i + τ + i = N τ N 1 b i ( a 2 N τ i 1 ) + i = 1 N τ 1 a i a i + τ

因为 ρ a ( τ ) + ρ b ( τ ) = 0 ,根据引理2知, ( a , b ) 0 i < N 2 a i = b i ;在 N 2 i < N 时, a i = b i ,所以

| ρ e ( τ ) + ρ f ( τ ) | = | i = N τ N 1 a i b 2 N τ i 1 + i = N τ N 1 b i ( a 2 N τ i 1 ) 2 a 0 a τ 2 b 0 b τ | = | 2 a 0 ( a τ + b τ ) | = 0

情形3:当 1 τ N 2 1 时,

ρ e ( τ ) = i = 1 N τ 1 a i a i + τ + i = N τ N 1 a i b 2 N τ i 1 + i = 1 N τ 1 b i b i + τ ρ f ( τ ) = i = 1 N τ 1 b i b i + τ + i = N τ N 1 b i ( a 2 N τ i 1 ) + i = 1 N τ 1 a i a i + τ

因为 ρ a ( τ ) + ρ b ( τ ) = 0 ,根据引理2知, ( a , b ) 0 i < N 2 a i = b i ,所以

| ρ e ( τ ) + ρ f ( τ ) | = | i = N τ N 1 a i b 2 N i τ 1 + i = N τ N 1 b i ( a 2 N i τ 1 ) 2 a 0 a τ 2 b 0 b τ | = | 4 a 0 a τ | = 4

2) 当 r 1 = N 2 1 , r 2 = N 2 ,可以得到 ( e , f ) ,即

e = ( e 0 , e 1 , , e N 1 ) = ( a 0 , a 1 , a 2 , , a N 2 , b N 2 , , b 1 , b 0 )   f = ( f 0 , f 1 , , f N 1 ) = ( b 0 , b 1 , b 2 , , b N 2 , a N 2 , , a 1 , a 0 )

根据 τ 取值范围分下面三种情形讨论 | ρ e ( τ ) + ρ f ( τ ) |

情形1:当 N 1 τ 2 N 3 时,

ρ e ( τ ) = i = 0 N 2 a i b 2 N τ i 3 ρ f ( τ ) = i = 0 N 2 b i ( a 2 N τ i 3 )

| ρ e ( τ ) + ρ f ( τ ) | = | i = 0 N 2 a i b 2 N τ i 3 i = 0 N 2 b i ( a 2 N τ i 3 ) | = 0

情形2:当 N 2 τ N 2 时,

ρ e ( τ ) = i = 0 N τ 2 a i a i + τ + i = N τ 1 N 2 a i b 2 N τ i 3 + i = 0 N τ 2 b i b i + τ ρ f ( τ ) = i = 0 N τ 2 b i b i + τ + i = N τ 1 N 2 b i ( a 2 N τ i 3 ) + i = 0 N τ 2 a i a i + τ

因为 ρ a ( τ ) + ρ b ( τ ) = 0 ,根据引理2知, ( a , b ) 0 i < N 2 a i = b i ;在 N 2 i < N 时, a i = b i ,所以

| ρ e ( τ ) + ρ f ( τ ) | = | i = N τ 1 N 2 a i b 2 N τ i 1 + i = N τ 1 N 2 b i ( a 2 N τ i 1 ) 2 a N 1 a N τ 1 2 b N 1 b N τ 1 | = | 2 a N 1 ( a N τ 1 + b N τ 1 ) | = 0

情形3:当 1 τ N 2 1 时,

ρ e ( τ ) = i = 0 N τ 2 a i a i + τ + i = N τ 1 N 2 a i b 2 N τ i 3 + i = 0 N τ 2 b i b i + τ ρ f ( τ ) = i = 0 N τ 2 b i b i + τ + i = N τ 1 N 2 b i ( a 2 N τ i 3 ) + i = 0 N τ 2 a i a i + τ

因为 ρ a ( τ ) + ρ b ( τ ) = 0 ,根据引理2知, ( a , b ) 0 i < N 2 a i = b i ,所以

| ρ e ( τ ) + ρ f ( τ ) | = | i = N τ 1 N 2 a i b 2 N τ i 3 + i = N τ 1 N 2 b i ( a 2 N τ i 3 ) 2 a N 1 a N τ 1 2 b N 1 b N τ 1 | = | 4 a N 1 a N τ 1 | = 4

综上所述, ( e , f ) 是长度为 2 N 2 、零相关区为 3 2 N 1 ,且在零相关区外的幅值为4的II型偶长Z-互补序列对。

为了更好地阐述上述定理,我们给出如下例子,并且例子的结果皆由Matlab得到。

1 ( a , b ) = ( + + + + + + + + + + , + + + + + + ) 是由引理2产生的长度为 N = 16 的GCP,验证定理1当 r 1 = 0 , r 2 = 2 N 1 的情况下产生得到的 ( e , f ) 是II型偶长Z-互补序列对。

二进制序列 ( e , f ) 通过定理1产生得到,当 r 1 = 0 , r 2 = 2 N 1

e = ( + + + + + + + + + + + + + + ) f = ( + + + + + + + + + + )

计算得到其非周期自相关函数和为

( | ρ e ( τ ) + ρ f ( τ ) | 0 29 ) = ( 60 , 4 7 , 0 22 )

所以 ( e , f ) 是一个长度为30的II型偶长Z-互补序列对,并且零相关区长度为 Z = 23

2 ( a , b ) = ( + + + + , + + + + + + ) 是由引理2产生的长度为 N = 8 的GCP,验证定理1当 r 1 = N 2 1 , r 2 = N 2 的情况下产生得到的 ( e , f ) 是II型偶长Z-互补序列对。

二进制序列 ( e , f ) 通过定理1产生得到,当 r 1 = N 2 1 , r 2 = N 2

e = ( + + + + + + + + + ) f = ( + + + + + + + + + + )

计算得到其非周期自相关函数和为

( | ρ e ( τ ) + ρ f ( τ ) | 0 13 ) = ( 28 , 4 3 , 0 10 )

所以 ( e , f ) 是一个长度为14的II型偶长Z-互补序列对,并且零相关区长度为 Z = 11 。现有II型EB-ZCP见表1

Table 1. Existing type II EB-ZCP

1. 现有II型 EB-ZCP

文献

长度

ZCZ

零相关区外的值

[7]

2 k N + 2 k 1 N Z + , k 2

2 k N + 2 k 1 N

4 v 2 k ( 2 N 1 )

[7]

3 N

3 N 1

2 N

[7]

14 N

14 N 1

4 N

[8]

2 m P

2 m P + 1 P

--

[11]

2 k + 2 N k { 1 , 2 , 3 , } N = 2 α 10 β 26 γ

( 2 k + 2 1 ) N

2 k × 4 N

[11]

2 N + 2 N = 2 α 10 β 26 γ

3 2 N + 2

4

[14]

8 N + 4

5 N + 2

8

[15]

2 N + 3

N + 2

2 or 6

[15]

4 N + 4

7 2 N + 4

8

定理1

2 N 2 N = 2 α 10 β 26 γ

3 2 N 1

4

本文与文献[11] [15]的构造方法相比,存在以下的不同之处。

1) 本文删除的码元是2个,文献[11]是插入2个码元,文献[15]是插入3个码元。

2) 本文删除的位置有2种方法,文献[11]的插入位置在种子对的后端,文献[15]的插入位置在种子对第1个码元前,中端以及最后1个码元后,本文的删除位置在种子对的前端和后端或者种子对的中端。

3) 本文构造的序列与文献[15]相比,其零相关区外的值更小。

4. 结语

本文主要研究了II型偶长Z-互补序列对,在二进制互补对的核的基础上,利用Turyn构造新的序列,在此序列上利用级联和删除2个码元,得到了长度为 2 N 2 , N = 2 α 10 β 26 γ 的II型EB-ZCP,其中 α 1 , β 0 , γ 0 α , β , γ 为非负整数。本文所得的II型EB-ZCP在特定的长度上是最优的,与现有的ZCPs相比包含许多新长度,其零相关区外的值较低,可以为无线通信系统提供更加性能优良的Z-互补对。

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