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Large Families of Ternary Sequences with Aperiodic Zero Correlation Zone Sequences for a Multi-Carrier DS-CDMA System
A new method for generating families of ternary spreading sequences is presented. The sequences have aperiodic zero correlation zones and large families are created for a specific sequence length. The sequences are proposed as spreading sequences to provide high capacity and cancel multipath and multiple access interference (MAI) in a single carrier (SC) or multi-carrier (MC) direct-spread code division multiple access (DS-CDMA) system. A Multi-carrier DS-CDMA system is simulated that employs the new sequences as spreading sequences in a multipath channel. Bit error rates (BER) and frame error rates (FER) for a range of Eb/No values are presented and it is demonstrated that the proposed sequences improve the BER and FER performance when used in place of masked Walsh Codes for the frequency selective fading channel evaluated, when a single correlator receiver is used on each sub-carrier
Sequence Design for Cognitive CDMA Communications under Arbitrary Spectrum Hole Constraint
To support interference-free quasi-synchronous code-division multiple-access
(QS-CDMA) communication with low spectral density profile in a cognitive radio
(CR) network, it is desirable to design a set of CDMA spreading sequences with
zero-correlation zone (ZCZ) property. However, traditional ZCZ sequences (which
assume the availability of the entire spectral band) cannot be used because
their orthogonality will be destroyed by the spectrum hole constraint in a CR
channel. To date, analytical construction of ZCZ CR sequences remains open.
Taking advantage of the Kronecker sequence property, a novel family of
sequences (called "quasi-ZCZ" CR sequences) which displays zero
cross-correlation and near-zero auto-correlation zone property under arbitrary
spectrum hole constraint is presented in this paper. Furthermore, a novel
algorithm is proposed to jointly optimize the peak-to-average power ratio
(PAPR) and the periodic auto-correlations of the proposed quasi-ZCZ CR
sequences. Simulations show that they give rise to single-user bit-error-rate
performance in CR-CDMA systems which outperform traditional non-contiguous
multicarrier CDMA and transform domain communication systems; they also lead to
CR-CDMA systems which are more resilient than non-contiguous OFDM systems to
spectrum sensing mismatch, due to the wideband spreading.Comment: 13 pages,10 figures,Accepted by IEEE Journal on Selected Areas in
Communications (JSAC)--Special Issue:Cognitive Radio Nov, 201
Full-length non-linear binary sequences with Zero Correlation Zone for multiuser communications
The research on new sets of sequences to be used asspreading codes in multiple user communications is still an activearea, despite the great amount of literature available since manyyears on this topic. In fact, new paradigms like dense anddecentralized wireless networks, where there is no centralcontroller to assign the resources to the nodes, are revamping theinterest on large sets of sequences providing adequate correlationproperties to support a big number of nodes, in potentially hostilechannels. This paper focuses on the Zero Correlation Zone (ZCZ)property exhibited by a family of non-linear binary sequencesfeaturing a great cardinality of their set and good securityrelatedfeatures, and provides evidence of their suitability tomultiuser communications, in channels affected by multipath
A Systematic Framework for the Construction of Optimal Complete Complementary Codes
The complete complementary code (CCC) is a sequence family with ideal
correlation sums which was proposed by Suehiro and Hatori. Numerous literatures
show its applications to direct-spread code-division multiple access (DS-CDMA)
systems for inter-channel interference (ICI)-free communication with improved
spectral efficiency. In this paper, we propose a systematic framework for the
construction of CCCs based on -shift cross-orthogonal sequence families
(-CO-SFs). We show theoretical bounds on the size of -CO-SFs and CCCs,
and give a set of four algorithms for their generation and extension. The
algorithms are optimal in the sense that the size of resulted sequence families
achieves theoretical bounds and, with the algorithms, we can construct an
optimal CCC consisting of sequences whose lengths are not only almost arbitrary
but even variable between sequence families. We also discuss the family size,
alphabet size, and lengths of constructible CCCs based on the proposed
algorithms
The Construction and Performance of a Novel Intergroup Complementary Code
 On the basis of the analyses for intergroup complementary (IGC) code and zero correlation zone complementary code, a novel IGC code has been proposed to adapt M-ary orthogonal code spreading spectrum system or quasi-synchronous CDMA system. The definition and construction methods of the new IGC codes are presented and an applied example is given in this paper. Theoretical research and simulation results show that the main advantages of the novel IGC code are as following: The code sets of the novel IGC code is more than IGC code under the same code length. The zero correlation zone length is longer than the intergroup IGC code, but shorter than the intergroup IGC code. Under the same code length, the auto-correlation performance of the novel IGC code is better than that of the IGC code, and both are of similar cross-correlation performance
Full-length non-linear binary sequences with Zero Correlation Zone for multiuser communications
none3noThe research on new sets of sequences that can be applied as spreading codes in multiple user communications is still an active area, even if this topic has been extensively investigated since long time. In fact, new communication paradigms like dense and decentralized wireless networks, where there is no central controller to assign the resources to the nodes, are revamping the interest on finding large sets of sequences providing adequate correlation properties to support a big number of nodes, in potentially hostile channels. This paper focuses on the Zero Correlation Zone (ZCZ) property exhibited by a family of nonlinear binary sequences featuring a great cardinality of their set, and good security-related features, and provides evidence of their suitability to multiuser communications, in channels affected by multipath.Sarayloo, M.; Gambi, E.; Spinsante, S.Sarayloo, Mahdiyar; Gambi, Ennio; Spinsante, Susann
A Direct Construction of Prime-Power-Length Zero-Correlation Zone Sequences for QS-CDMA System
In recent years, zero-correlation zone (ZCZ) sequences are being studied due
to their significant applications in quasi-synchronous code division multiple
access (QS-CDMA) systems and other wireless communication domains. However, the
lengths of most existing ZCZ sequences are limited, and their parameters are
not flexible, which are leading to practical limitations in their use in
QS-CDMA and other communication systems. The current study proposes a direct
construction of ZCZ sequences of prime-power length with flexible parameters by
using multivariable functions. In the proposed construction, we first present a
multivariable function to generate a vector with specific properties; this is
further used to generate another class of multivariable functions to generate
the desired -ZCZ sequence set, where is a prime
number, are positive integers, and . The constructed ZCZ
sequence set is optimal for the binary case and asymptotically optimal for the
non-binary case by the \emph{Tang-Fan-Matsufuji} bound. Moreover, a relation
between the second-order cosets of first-order generalized Reed-Muller code and
the proposed ZCZ sequences is also established. The proposed construction of
ZCZ sequences is compared with existing constructions, and it is observed that
the parameters of this ZCZ sequence set are a generalization of that of in some
existing works. Finally, the performance of the proposed ZCZ-based QS-CDMA
system is compared with the Walsh-Hadamard and Gold code-based QS-CDMA system
A Direct Construction of Intergroup Complementary Code Set for CDMA
A collection of mutually orthogonal complementary codes (CCs) is said to be complete complementary codes (CCCs) where the number of CCs are equal to the number of constituent sequences in each CC. Intergroup complementary (IGC) code set is a collection of multiple disjoint code groups with the following correlation properties: (1) inside the zero-correlation zone (ZCZ), the aperiodic autocorrelation function (AACF) of any IGC code is zero for all nonzero time shifts; (2) the aperiodic cross-correlation function (ACCF), of two distinct IGC codes, is zero for all time shifts inside the ZCZ when they are taken from the same code groups; and (3) the ACCF, for two IGC codes from two different code groups, is zero everywhere. IGC code set has a larger set size than CCC, and both can be applicable in multicarrier code-division multiple access (CDMA). In this chapter, we present a direct construction of IGC code set by using second-order generalized Boolean functions (GBFs), and our IGC code set can support interference-free code-division multiplexing. We also relate our construction with a graph where the ZCZ width depends on the number of isolated vertices present in a graph after the deletion of some vertices. Here, the construction that we propose can generate IGC code set with more flexible parameters
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