Aperiodic complementary sequence sets with zero correlation zone over 8-QAM+ constellation

A zero-correlation zone (ZCZ) sequence set consisting of multiple ZCZ sequence subsets is said to be an asymmetric ZCZ (A-ZCZ) sequence set if and only if the cross-correlation function (CCF) between two arbitrary sequence which belong to different subsets has quite a large zero-cross-correlation zone (ZCCZ). In such an A-ZCZ sequence set, each subset is a conventional ZCZ sequence set. Our proposed A-ZCZ sequence set can be generated by interleaving any perfect sequence of length P = Nqk with N > 1, q ≥ 1 and k > 1. It is optimal or quasi-optimal conventional ZCZ sequence set if q = 1. The proposed A-ZCZ sequence set are applied to quasi-synchronous code-division multiple-access (QS-CDMA) systems and it can hypothetically achieve larger ZCZ than conventional ZCZ sequence set, as well as eliminating both multiple access and multipath interference in the QS-CDMA system.

For suppressing multiple access interference (MAI) in a CDMA communication system, complementary sequence sets are employed as spreading sequences in such system. In this paper, we present a method for constructing a family of quaternary periodic complementary sequence sets, which arises from the conversion of the existing binary periodic complementary sequence sets with odd period of sub-sequences. The period of sub-sequences in the proposed sequence sets is twice as long as the one of the binary sequence sets employed, which is a drawback in the proposed method. Finally, some examples are given in order to illuminate the validity of the new method.

In this letter, we propose a novel scheme to construct a novel class of 2-D binary sequences with zero correlation zone, which is based on perfect arrays and orthogonal sequences. Compared with all existing 2-D binary sequences, the proposed construction can generate more sets of two-dimensional binary sequences with long zero correlation zone. Moreover, the constructed 2-D sequence sets could be applied directly, such as arrays of sound sources, position detection arrays, phased-array antennas, time-frequency coding, and spatial correlation.

The present paper introduces a new approach to the construction of a sequence set with a zero-correlation zone (ZCZ). This sequence set is referred to as a zero-correlation zone sequence set. The proposed sequence construction can generate an optimal ZCZ sequence set, the member size of which reaches the theoretical bound. The proposed sequence construction generates a ZCZ sequence set from a perfect sequence and a Hadamard matrix.

Zero correlation zone (ZCZ) sequences are a class of spreading sequences having ideal auto-correlation and cross correlation in a zone around the origin. They have been extensively studied in recent years due to their important applications in quasi-synchronous code division multiple access systems. In this paper, a construction of ZCZ sequence sets is proposed based on perfect nonlinear functions. It generates multiple ZCZ sequence sets with the properties: 1) each sequence is perfect in the sense that its out-of-phase auto-correlation is always zero; 2) each ZCZ sequence set is optimal with respect to the Tang–Fan–Matsufuji bound in which all the sequences are pairwise cyclically distinct; and 3) the maximum inter-set cross correlation of multiple sequence sets achieves the well-known Sarwate bound.

The application of two dimensional (2D) complementary sequences in ultra wideband (UWB) communication systems has brought a new opportunity for such systems' development. To binary, ternary or polyphase two-dimensional sequence sets, the concept of 2D complementary sequences is generalized to a 2D generalized complementary orthogonal sequence set (GCOSS) with zero correlation zone (ZCZ); a novel lower bound for such a sequence set is derived and presented.

For all DS-CDMA based satellite navigation systems which have been emerging these days, it is required to design a set of spreading sequences to eliminate both multi-access and multi-path interference. In a typical CDMA system, it is well-known that it is highly impossible for the spreading sequences to possess both ideal cross-correlation and ideal auto-correlation properties simultaneously. Recently, Zero Correlation Zone (ZCZ) sequences based on the concept of generalized orthogonality (GO), with well-defined zero correlation zone property has been introduced. In this paper, we described the Zero Correlation Zone (ZCZ) sequence algorithm and its possibility to use in satellite navigation system has been discussed and presented.

The present paper introduces the construction of a class of sequence sets with zero-correlation zones called zero-correlation zone sequence sets. The proposed zero-correlation zone sequence set can be generated from an arbitrary perfect sequence and an arbitrary Golay complementary sequence pair. The proposed construction is a generalization of the zero-correlation zone sequence construction previously reported by the present author. The proposed sequence set can successfully provide CDMA communication without co-channel interference.

In this letter, a construction of zero correlation zone (ZCZ) sequence sets over Gaussian integers is presented. Based on the characteristic sets of binary pseudo-random sequences and shift sequences, ZCZ Gaussian integer sequence sets with optimal or almost optimal parameters are constructed. Moreover, the ZCZ lengths of resultant ZCZ Gaussian integer sequence sets are flexible.

Based on the known binary sequence sets and Gray mapping, a new method for constructing quaternary sequence sets is presented and the resulting sequence sets' properties are investigated. As three direct applications of the proposed method, when we choose the binary aperiodic, periodic, and Z-complementary sequence sets as the known binary sequence sets, the resultant quaternary sequence sets are the quaternary aperiodic, periodic, and Z-complementary sequence sets, respectively. In comparison with the method proposed by Jang et al., the new method can cope with either both the aperiodic and periodic cases or both even and odd lengths of sub-sequences, whereas the former is only fit for the periodic case with even length of sub-sequences. As a consequence, by both our and Jang et al.'s methods, an arbitrary binary aperiodic, periodic, or Z-complementary sequence set can be transformed into a quaternary one no matter its length of sub-sequences is odd or even. Finally, a table on the existing quaternary periodic complementary sequence sets is given as well.

A construction of shift sequence sets is proposed. Multiple distinct shift sequence sets are obtained by changing the parameters of the shift sequences. The shift sequences satisfy the conditions that P|L and P ≥ 2, where P is the length of the shift sequences, L is the length of the zero-correlation zone or low-correlation zone (ZCZ/LCZ). Then based on these shift sequence sets, many shift distinct ZCZ/LCZ sequence sets are constructed by using interleaving technique and complex Hadamard matrices. Furthermore, the new construction is optimal under the conditions proposed in this paper. Compared with previous constructions, the proposed construction extends the number of shift distinct ZCZ/LCZ sequence sets, so that more sequence sets are obtained for multi-cell quasi-synchronous code-division multiple access (QS-CDMA) systems.

New constructions of quaternary low correlation zone sequence sets

Broadband communication systems of the current generation are likely to offer higher bit rates for delivering high-speed multimedia services to the end users. The achievable capacity and data rate of wireless communication systems are limited to fading channels varying with time, leading to multiple access interference (MAI) and multipath interference (MPI). In this paper, we investigate downlink single-input multiple output transmission for complementary coded code-division multiple access (CC-CDMA) systems working in channels with multipath fading. Here, parallel interference cancellation is employed for analysis of CC-CDMA with different frequency domain equalization schemes to eliminate MPI and MAI over multipath fading channels. Error rate analysis for CC-CDMA employing receiver diversity is assessed using simulations under varying channel parameters. Further, we compare different equalization schemes to show the superiority of regularized zero forcing in reducing the error rate of CC-CDMA systems.

We present a new construction for two-dimensional, perfect autocorrelation arrays over roots of unity. These perfect arrays are constructed from a block of perfect column sequences. Other blocks are constructed from the first block, to generate a block-circulant structure. The columns are then multiplied by a perfect sequence over roots of unity, which, when folded into an array commensurate with our block width has the array orthogonality property. The size of the arrays is commensurate with the length of the underlying perfect sequences. For a given size we can construct an exponential number of inequivalent perfect arrays. For each perfect array we construct a family of arrays whose pairwise cross-correlation values are almost all zero (large zero correlation zones (ZCZ)). We present experimental evidence that this construction for perfect arrays can be generalized to higher dimensions.

The present paper introduces an integrated construction of binary sequences having a zero-correlation zone. The cross-correlation function and the side-lobe of the auto-correlation function of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. The proposed method enables more flexible design of the binary zero-correlation zone sequence set with respect to its member size, length, and width of zero-correlation zone. Several previously reported sequence construction methods of binary zero-correlation zone sequence sets can be explained as special cases of the proposed method.