3,069 research outputs found
Optimization Methods for Designing Sequences with Low Autocorrelation Sidelobes
Unimodular sequences with low autocorrelations are desired in many
applications, especially in the area of radar and code-division multiple access
(CDMA). In this paper, we propose a new algorithm to design unimodular
sequences with low integrated sidelobe level (ISL), which is a widely used
measure of the goodness of a sequence's correlation property. The algorithm
falls into the general framework of majorization-minimization (MM) algorithms
and thus shares the monotonic property of such algorithms. In addition, the
algorithm can be implemented via fast Fourier transform (FFT) operations and
thus is computationally efficient. Furthermore, after some modifications the
algorithm can be adapted to incorporate spectral constraints, which makes the
design more flexible. Numerical experiments show that the proposed algorithms
outperform existing algorithms in terms of both the quality of designed
sequences and the computational complexity
New Constructions of Zero-Correlation Zone Sequences
In this paper, we propose three classes of systematic approaches for
constructing zero correlation zone (ZCZ) sequence families. In most cases,
these approaches are capable of generating sequence families that achieve the
upper bounds on the family size () and the ZCZ width () for a given
sequence period ().
Our approaches can produce various binary and polyphase ZCZ families with
desired parameters and alphabet size. They also provide additional
tradeoffs amongst the above four system parameters and are less constrained by
the alphabet size. Furthermore, the constructed families have nested-like
property that can be either decomposed or combined to constitute smaller or
larger ZCZ sequence sets. We make detailed comparisons with related works and
present some extended properties. For each approach, we provide examples to
numerically illustrate the proposed construction procedure.Comment: 37 pages, submitted to IEEE Transactions on Information Theor
New Sets of Optimal Odd-length Binary Z-Complementary Pairs
A pair of sequences is called a Z-complementary pair (ZCP) if it has zero
aperiodic autocorrelation sums (AACSs) for time-shifts within a certain region,
called zero correlation zone (ZCZ). Optimal odd-length binary ZCPs (OB-ZCPs)
display closest correlation properties to Golay complementary pairs (GCPs) in
that each OB-ZCP achieves maximum ZCZ of width (N+1)/2 (where N is the sequence
length) and every out-of-zone AACSs reaches the minimum magnitude value, i.e.
2. Till date, systematic constructions of optimal OB-ZCPs exist only for
lengths , where is a positive integer. In this
paper, we construct optimal OB-ZCPs of generic lengths (where are non-negative integers and
) from inserted versions of binary GCPs. The key leading to the
proposed constructions is several newly identified structure properties of
binary GCPs obtained from Turyn's method. This key also allows us to construct
OB-ZCPs with possible ZCZ widths of , and through proper
insertions of GCPs of lengths , respectively. Our proposed OB-ZCPs have applications in
communications and radar (as an alternative to GCPs)
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