Quaternary Low Correlation Zone Research Articles

New constructions of quaternary low correlation zone sequence sets

Sequence sets with low correlation have very important applications in modern communication systems. As in quasi-synchronous code-division multiple access (QS-CDMA) system, sequence sets with low correlation zone (LCZ) perform better than other well-known sequence sets. Furthermore, binary or quaternary sequence sets are preferred because of their easy implementation. In this paper, based on the inverse Gray mapping and special binary sequence pairs, new quaternary LCZ sequence sets were constructed. In the LCZ, the maximum of the nontrivial autocorrelation and crosscorrelation values is 1 which show that the QS-CDMA system used the new sequences sets can control the interference in a very low level.

A New Method for Constructing Quaternary Sequence Sets with Low Correlation Zone

A method of constructing multiple quaternary low correlation zone (LCZ) sequence sets with the same parameters is proposed. Two mappings which can map two binary variables to a quaternary one are presented. Based on different mappings, new quaternary LCZ sequence sets are constructed. Furthermore, based on the same mapping, the parameters of shift sequences are changed to extend the number of LCZ sequence sets and there is only one shift equivalent sequence from different sets. The parameters of the LCZ sequence sets can be flexibly chosen. Compared with previous methods, the proposed construction extends the number of quaternary LCZ sequence sets. As a result, more spreading sequences are provided for multi-cell quasi-synchronous code-division multiple-access systems.

A new class of quaternary LCZ sequence sets

In this article, we present a construction of low correlation zone (LCZ) sequence sets. This construction gives a new class of quaternary LCZ sequence sets. Furthermore, we observe a generalization of the LCZ sequence sets in Kim et al. (IEEE Trans Inform Theory 52(10):4607---4616, 2006) by using an orthogonal transformation. The obtained LCZ sequence sets are optimal with respect to the Tang, Fan and Matsufuji bound.

A Construction of Quaternary Low Correlation Zone Sequence Sets from Binary Low Correlation Zone Sequence Sets Improving Optimality

In this letter, we propose a new construction of quaternary low correlation zone (LCZ) sequence set using binary LCZ sequence sets and an inverse Gray mapping. The new construction method provides optimal quaternary LCZ sequence sets even if the employed binary LCZ sequence set is suboptimal. The optimality is improved at the price of alphabet extension.

New Method to Extend the Number of Quaternary Low Correlation Zone Sequence Sets

In this correspondence, a new method to extend the number of quaternary low correlation zone (LCZ) sequence sets is presented. Based on the inverse Gray mapping and a binary sequence with ideal two-level auto-correlation function, numbers of quaternary LCZ sequence sets can be generated by choosing different parameters. There is at most one sequence cyclically equivalent in different LCZ sequence sets. The parameters of LCZ sequence sets are flexible.

New construction of quaternary low correlation zone sequence sets from binary low correlation zone sequence sets

In this paper, using binary (N, M, L, є) low correlation zone (LCZ) sequence sets, we construct new quaternary LCZ sequence sets with parameters (2N, 2M, L, 2є). Binary LCZ sequences for the construction should have period N ≡ 3 mod 4, L|N, and the balance property. The proposed method corresponds to a quaternary extension of the extended construction of binary LCZ sequence sets proposed by Kim, Jang, No, and Chung [1].

New Extension Method of Quaternary Low Correlation Zone Sequence Sets

We propose an extension method of quaternary low correlation zone (LCZ) sequence set with odd period. From a quaternary LCZ sequence set with parameters (N , M, L, 1), the proposed method constructs a new quaternary LCZ sequence set with parameters (2N, 2M, L, 2), where N is odd. If the employed LCZ sequence set in the construction is optimal, the extended LCZ sequence set becomes also optimal where N = kL, L > 4, and k >2.

New Design of Quaternary Low-Correlation Zone Sequence Sets and Quaternary Hadamard Matrices

In this correspondence, we present new construction methods for quaternary low-correlation zone (LCZ) sequence sets from a binary sequence with good autocorrelation. We show that the sets obtained by our methods are optimal or nearly optimal with respect to the Tang-Fan-Matsufuji bound and that our construction methods are more flexible than any other previous constructions in the sense of period, family size, and zone size. We also give a construction method for a quaternary LCZ sequence set from a binary LCZ sequence set. Finally, we give a new construction method for quaternary Hadamard matrices by the inverse of the Gray map.

Multicode MIMO Systems With Quaternary LCZ and ZCZ Sequences

In this paper, we propose multicode multiple-input-multiple-output (MIMO) systems with quaternary low-correlation zone (LCZ) and zero-correlation zone (ZCZ) sequences as spreading codes. Quaternary LCZ and ZCZ sequences have very low correlation values when the time shifts between these sequences are within the predetermined correlation zone, and thus, the multiuser or multipath interference can be substantially reduced when the delay is within a few chips. The bit error probability of the proposed systems is theoretically analyzed, which is numerically confirmed. It is also numerically shown that the performance of the multicode MIMO systems with quaternary LCZ and ZCZ sequences is better than that of the conventional multicode MIMO systems with quaternary spreading codes constructed from pairs of binary Hadamard codes.

A New Construction of Optimal p2-Ary Low Correlation Zone Sequences Using Unified Sequences

In this paper, given an integer e and n such that e|n, and a prime p, we propose a method of constructing optimal p2-ary low correlation zone (LCZ) sequence set with parameters (pn-1, pe-1, (pn-1)/(pe-1), 1) from a p-ary sequence of the same length with ideal autocorrelation. The resulting p2-ary LCZ sequence set can be viewed as the generalization of the optimal quaternary LCZ sequence set by Kim, Jang, No, and Chung in respect of the alphabet size. This generalization becomes possible due to a completely new proof comprising any prime p. Under this proof, the quaternary case can be considered as a specific example for p = 2.

New Constructions of Quaternary Low Correlation Zone Sequences

In this paper, given a composite integer n, we propose a method of constructing quaternary low correlation zone (LCZ) sequences of period 2/sup n/-1 from binary sequences of the same length with ideal autocorrelation. These new sequences are optimal with respect to the bound by Tang, Fan, and Matsufuji. The correlation distributions of these new quaternary LCZ sequences constructed from m-sequences and Gordon-Mills-Welch (GMW) sequences are derived.