Constant weight code is an important error-correcting control code in communications. Basic structure of constant weight codes for some arriving at Johnson bound, A（n, 2u, w）, is presented. Some correlative property...Constant weight code is an important error-correcting control code in communications. Basic structure of constant weight codes for some arriving at Johnson bound, A（n, 2u, w）, is presented. Some correlative propertys of the codes, the solution of arriving at Johnson bound, and the results on the couple constant code and some constant weight codes are discussed. The conclusion is verified through four examples.展开更多
Constant weight codes (CWCs) are an important class of codes in coding theory. Generalized Steiner systems GS(2, k, v, g) were first introduced by Etzion and used to construct optimal nonlinear CWCs over an alphabet o...Constant weight codes (CWCs) are an important class of codes in coding theory. Generalized Steiner systems GS(2, k, v, g) were first introduced by Etzion and used to construct optimal nonlinear CWCs over an alphabet of size g+1 with minimum Hamming distance 2k - 3, in which each codeword has length v and weight k. In this paper, Weil's theorem on character sum estimates is used to show that there exists a GS(2,4, v, 3) for any prime v≡1 (mod 4) and v > 13. From the coding theory point of view, an optimal nonlinear quaternary (v, 5,4) CWC exists for such a prime v.展开更多
CONSTANT weight codes are very important in coding theory for its application to communication. In refs. [1—5], the undetected error probabilities (UEP)of binary nonlinear constant weight codes (BNCW) were studied, a...CONSTANT weight codes are very important in coding theory for its application to communication. In refs. [1—5], the undetected error probabilities (UEP)of binary nonlinear constant weight codes (BNCW) were studied, and Wang et al. showed that when n】8, BNCW codes (n, 2, ω) were not proper, Wang proposed a conjecture that when n】4δ and δ】 1, BNCW codes (n, 2δ, ω) are not proper. in this note, the error-detecting abilities展开更多
In this paper we consider the problem of finding bounds on the size of lexicographic constant-weight equidistant codes over the alphabet of three, four and five elements with 2 ≤ w 【n ≤ 10. Computer search of lexic...In this paper we consider the problem of finding bounds on the size of lexicographic constant-weight equidistant codes over the alphabet of three, four and five elements with 2 ≤ w 【n ≤ 10. Computer search of lexicographic constant-weight equidistant codes is performed. Tables with bounds on the size of lexicographic constant-weight equidistant codes are presented.展开更多
针对普遍单脉冲位置调制的不足,在已有的UWB(Ultra-Wideband)脉冲位置调制研究基础上,提出了一种改进的双极性多脉冲位置调制(AMPPM:Ambipolar Multi-Pulse Position Modulation)的UWB跳时调制方案,并对其加性高斯白噪声(AWGN:Additive ...针对普遍单脉冲位置调制的不足,在已有的UWB(Ultra-Wideband)脉冲位置调制研究基础上,提出了一种改进的双极性多脉冲位置调制(AMPPM:Ambipolar Multi-Pulse Position Modulation)的UWB跳时调制方案,并对其加性高斯白噪声(AWGN:Additive white Gaussian Noise)下的信道容量,最大可靠通信距离等性能指标进行了理论分析。理论分析及实验数值结果表明,在相同的条件下,与普通的单脉冲位置调制(PPM:Pulse Position Modulation)相比,AMPPM能获得较高的容量,即在给定可实现脉冲宽度下可获得更高的通信速率。仿真结果表明,当脉冲宽度为0.5 ns时,L进制AMPPM可达到333 Mbit/s的速率,而同等条件下的L进制PPM仅能达到167 Mbit/s的速率。同时AMPPM在最大可靠通信距离指标方面也较相应的PPM及脉冲幅度调制(PAM:Pulse Amplitude Modulation)有改善,在100 Mbit/s及10-4的误码率下可达到8 m的通信距离。展开更多
文摘Constant weight code is an important error-correcting control code in communications. Basic structure of constant weight codes for some arriving at Johnson bound, A（n, 2u, w）, is presented. Some correlative propertys of the codes, the solution of arriving at Johnson bound, and the results on the couple constant code and some constant weight codes are discussed. The conclusion is verified through four examples.
基金This work was supported by the National Natural Science Foundation of China(Grant No.10471127)for the first authorby Tianyuan Mathematics Foundation of NSFC(Grant No.A0324644)Guangxi Science Foundation and the Foundation of the Education Department of Guangxi Province for the second author.
文摘Constant weight codes (CWCs) are an important class of codes in coding theory. Generalized Steiner systems GS(2, k, v, g) were first introduced by Etzion and used to construct optimal nonlinear CWCs over an alphabet of size g+1 with minimum Hamming distance 2k - 3, in which each codeword has length v and weight k. In this paper, Weil's theorem on character sum estimates is used to show that there exists a GS(2,4, v, 3) for any prime v≡1 (mod 4) and v > 13. From the coding theory point of view, an optimal nonlinear quaternary (v, 5,4) CWC exists for such a prime v.
文摘CONSTANT weight codes are very important in coding theory for its application to communication. In refs. [1—5], the undetected error probabilities (UEP)of binary nonlinear constant weight codes (BNCW) were studied, and Wang et al. showed that when n】8, BNCW codes (n, 2, ω) were not proper, Wang proposed a conjecture that when n】4δ and δ】 1, BNCW codes (n, 2δ, ω) are not proper. in this note, the error-detecting abilities
文摘In this paper we consider the problem of finding bounds on the size of lexicographic constant-weight equidistant codes over the alphabet of three, four and five elements with 2 ≤ w 【n ≤ 10. Computer search of lexicographic constant-weight equidistant codes is performed. Tables with bounds on the size of lexicographic constant-weight equidistant codes are presented.
