Constructions of Quaternary Periodic Complementary Sequence Sets with Zero Correlation Zone

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.

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.

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.

This letter is focused on increasing the zero correlation zone (ZCZ) of even-length binary Z-complementary pairs (EB-ZCPs). Till date, the maximum ZCZ ratio (i.e., ZCZ width over the sequence length) for systematically constructed EB-ZCPs is 2/3. In this letter, we give a construction of EB-ZCPs with lengths 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">α+2</sup> 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</sup> 26 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γ</sup> + 2 (where α, β, and γ are nonnegative integers) and ZCZ widths 3 × 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">α</sup> 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</sup> 26 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γ</sup> + 1, thus achieving asymptotic ZCZ ratio of 3/4. The proposed EB-ZCPs are constructed via proper insertion of concatenated odd-length binary ZCPs. The ZCZ width is proved by exploiting several newly identified intrinsic structure properties of binary Golay complementary pairs, obtained from Turyn's method. The proposed EB-ZCPs have aperiodic autocorrelation sums (AACS) magnitude of 4 outside the ZCZ region (except for the last time-shift taking AACS value of zero).

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.

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.

Aperiodic complementary sequence sets (ACSS) with zero correlation zone (ZCZ) over 8-QAM+ constellation are defined as 8-QAM+ Z-ACSS. New shift vectors and mappings are used to transform perfect ternary sequences to 8-QAM+ orthogonal sequences, meanwhile based on p-phase orthogonal sequence sets, p=2, 3, 4, 8-QAM+ Z-ACSS are constructed by interleaving operation in this paper. The parameters of the resultant 8-QAM+Z-ACSS can be set flexibly to achieve the theoretical bound, which means the Z-ACSS proposed are optimal. 8-QAM+ Z-ACSS can be used in quasi-synchronous CDMA (QS-CDMA) communication systems with high transmission data rate (TDR) and multi-users to remove the multiple access interference (MAI) and multi-path interference (MPI).

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.

This paper reports how a novel direct-sequence UWB transceiver, utilizing Bridge function sequence as direct sequence, works in the wireless multipath environment. It is acknowledged that the Bridge function sequences have zero correlation zones (ZCZs) in their auto-correlation functions (ACFs). Due to the ZCZ properties of Bridge function sequences, the proposed direct-sequence UWB, using Bridge function sequence with properly chosen shift parameter, features a better performance on avoiding multipath interference than the one utilizing other spreading sequences without ZCZ. The theoretical justification of the proposed approach, together with its achievable performance in computer simulation, is presented in detail.

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.

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 paper, we analyze the bit error rate (BER) performance of synchronous optical code division multiple access (OCDMA) system using an optical zero-correlation zone (ZCZ) sequence set over diffuse link by computer simulation, and evaluate the influence of inter-symbol interference (ISI) on the system. The optical ZCZ sequence set is a set of pairs of binary and bi-phase sequences with zero-correlation zone. As a result, the ISI can suppress by extension of zero-correlation zone.

Zero correlation zone (ZCZ) sequence sets play an important role in interference-free quasi-synchronous code-division multiple access communications. In this paper, for the first time, we investigate the periodic correlation properties of polyphase sequences obtained from paraunitary (PU) matrices, which shows the inherent relationship between PU matrix and ZCZ sequence sets. Our investigation suggests that any arbitrary PU matrix can produce ZCZ sequence sets by controlling its expanded form. The key idea is to impose certain restrictions on the expanded forms of the PU matrices to enable precise computation of the periodic correlation functions of the constructed sequences. We show that our proposed construction leads to near-optimal ZCZ sequence sets with regard to the ZCZ set size upper bound.

Direct sequence spread spectrum (DSSS) techniques are commonly used for characterizing RF communications channels. These techniques have relative immunity to interference and do not require a direct reference connection between the transmitter and receiver. Current DSSS propagation measurement systems use a pseudo noise (PN) sequence to probe the impulse response of the channel. However, the use of PN sequences can introduce noise into the measurements. This noise is caused by a bias term that is inversely proportional to the length of the PN-Sequence, and limits the dynamic range of the measurement system. In this paper it is shown that this bias term will not be present when zero correlation zone (ZCZ) sequences are used. Consequently the dynamic range of the measurement system is limited by the SNR instead of the sequence itself. This paper also provides test data to show the effects of the bias term and to compare and contrast the use of PN and ZCZ sequences.

The authors propose a novel use of zero correlation zone (ZCZ) codes to increase the performance of quasi- synchronous code division multiple access (CDMA) systems. In this new approach, each spread sequence associated to a active user is a concatenation of two or more ZCZ sequences. In the receiver, each of the component sequences is separately correlated in order to recover the original information. A comparison to the convencional receiver is fulfilled by analyzing the performance of both schemes in a multipath Rayleigh fading channel and similar system parameters.