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A family \mathcal IP8 of sequences over the 8-ary quadrature-pulse amplitude modulation (Q-PAM) constellation with asymptotically optimal correlation property was presented by Anand and Kumar in 2008. This is the only known family of sequences over the quadrature amplitude modulation (QAM) constellation whose correlation magnitude asymptotically achieves the Welch bound. In this paper, a larger family \mathcal IP8^{\text {new}} of sequences with the same correlation magnitude as that of \mathcal IP8 but double family size is obtained. Moreover, the correlation distributions of \mathcal IP8 and \mathcal IP8^{\text {new}} are also determined for two particular cases in terms of the property of a class of exponential sums over Galois rings. It is also shown that more classes of QAM and Q-PAM sequences with low correlation and larger family size can be obtained from our approach. [ABSTRACT FROM AUTHOR]

Optical orthogonal codes (OOCs) are widely used as spreading codes in optical fiber networks. In this paper, a bound on the code size of 2-D OOCs with both at most one-pulse per wavelength (AM-OPPW) and at most one-pulse per time slot (AM-OPPTS) is derived. Accordingly, two constructions of optimal 2-D OOCs with both AM-OPPW and AM-OPPTS are proposed via the generalized cyclotomic classes. Furthermore, optimal 2-D OOC with AM-OPPW can be also constructed by adding more codewords into the 2-D OOCs with both AM-OPPW and AM-OPPTS. [ABSTRACT FROM PUBLISHER]

In this paper, a new family of quadriphase sequences with period 4(2 − 1) is proposed for n = me, where m is an odd integer. The correlation values of the family, their distribution, and the linear spans of the proposed sequences are completely determined under two situations. [ABSTRACT FROM AUTHOR]

In this paper, we revisit a method to produce binary sequences using the most significant bit map from \bf Z4 to the binary field. This method is useful for the construction of binary sequences with low correlation and large family size. There may be more cases where starting with \bf Z4 could help researchers design new low correlation sequences for code-division multiple access application. [ABSTRACT FROM AUTHOR]

Abstract: Let be an odd prime and . Based on the theory of quadratic forms over finite fields of odd characteristic, we generalize the binary construction by Yu and Gong to -ary case. As a result, we obtain a new family of -ary sequences of period for arbitrary positive integers and with . It is shown that, for a given , has family size , maximum correlation , and maximum linear span . In particular, the new family contains Tang, Udaya, and Fan’s construction as a subset, if an -sequence is excluded. [Copyright &y& Elsevier]