48 research outputs found
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
A Direct Construction of 2D-CCC with Arbitrary Array Size and Flexible Set Size Using Multivariable Function
Recently, two-dimensional (2D) array codes have been found to have
applications in wireless communication.In this paper, we propose direct
construction of 2D complete complementary codes (2D-CCCs) with arbitrary array
size and flexible set size using multivariable functions (MVF). The
Peak-to-mean envelope power ratio (PMEPR) properties of row and column
sequences of the constructed 2D-CCC arrays are investigated. The proposed
construction generalizes many of the existing state-of-the-art such as Golay
complementary pair (GCP), one-dimensional (1D)-CCC, 2D Golay complementary
array set (2D-GCAS), and 2D-CCC with better parameters compared to the existing
work
A Direct and Generalized Construction of Polyphase Complementary Set with Low PMEPR and High Code-Rate for OFDM System
A major drawback of orthogonal frequency division multiplexing (OFDM) systems
is their high peak-to-mean envelope power ratio (PMEPR). The PMEPR problem can
be solved by adopting large codebooks consisting of complementary sequences
with low PMEPR. In this paper, we present a new construction of polyphase
complementary sets (CSs) using generalized Boolean functions (GBFs), which
generalizes Schmidt's construction in 2007, Paterson's construction in 2000 and
Golay complementary pairs (GCPs) given by Davis and Jedwab in 1999. Compared
with Schmidt's approach, our proposed CSs lead to lower PMEPR with higher
code-rate for sequences constructed from higher-order () GBFs. We
obtain polyphase complementary sequences with maximum PMEPR of and
where are non-negative integers that can be easily derived
from the GBF associated with the CS
A Direct Construction of Optimal Symmetrical Z-Complementary Code Sets of Prime Power Lengths
This paper presents a direct construction of an optimal symmetrical
Z-complementary code set (SZCCS) of prime power lengths using a multi-variable
function (MVF). SZCCS is a natural extension of the Z-complementary code set
(ZCCS), which has only front-end zero correlation zone (ZCZ) width. SZCCS has
both front-end and tail-end ZCZ width. SZCCSs are used in developing optimal
training sequences for broadband generalized spatial modulation systems over
frequency-selective channels because they have ZCZ width on both the front and
tail ends. The construction of optimal SZCCS with large set sizes and prime
power lengths is presented for the first time in this paper. Furthermore, it is
worth noting that several existing works on ZCCS and SZCCS can be viewed as
special cases of the proposed construction
New Correlation Bound and Construction of Quasi-Complementary Code Sets
Quasi-complementary sequence sets (QCSSs) have attracted sustained research
interests for simultaneously supporting more active users in multi-carrier
code-division multiple-access (MC-CDMA) systems compared to complete
complementary codes (CCCs). In this paper, we investigate a novel class of
QCSSs composed of multiple CCCs. We derive a new aperiodic correlation lower
bound for this type of QCSSs, which is tighter than the existing bounds for
QCSSs. We then present a systematic construction of such QCSSs with a small
alphabet size and low maximum correlation magnitude, and also show that the
constructed aperiodic QCSSs can meet the newly derived bound asymptotically