Kyeongcheol Yang

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In this paper, the notion of quasi-orthogonal sequence (QOS) as a means of increasing the number of channels in synchronous code-division multiple-access (CDMA) systems that employ Walsh sequences for spreading information signals and separating channels is introduced. It is shown that a QOS sequence may be regarded as a class of bent (almost bent)(More)
Abstracf-The weight hierarchy of a linear code is the set of generalized Hamming weights of the code. In this paper, we consider geometric Goppa codes and provide a lower bound on their generalized Hamming weights similar to Goppa's lower bound on their minimum distance. In the particular case of Hermitian codes, exact results on the second and third(More)
In this paper we construct M-ary sequence families from power residue sequences of odd prime period p and their constant multiple sequences using the shift-and-add method, when M is a divisor of p - 1. We show that the maximum correlation values of the proposed sequence families of size p + M - 2 and (M - 1)<sup>2</sup> (p - 1)/2 + M - 1 are upper bounded(More)
In this correspondence, we present a construction for binary sequences ( ) of period = 1 for an odd prime based on the polynomial ( + 1) + + , and discuss them in some cases of parameters and . We show that new sequences from our construction are balanced or almost balanced and have optimal three-level autocorrelation for the case when the polynomial ( +1)(More)