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New Complete Complementary Codes for PeaktoMean Power Control in MultiCarrier CDMA
"... Owing to the zero nontrivial aperiodic correlation sum properties, complete complementary codes (CCC) have been applied to asynchronous multicarrier codedivision multipleaccess (MCCDMA) communications in order to provide zero interference performance. When each complementary code is arranged to ..."
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Owing to the zero nontrivial aperiodic correlation sum properties, complete complementary codes (CCC) have been applied to asynchronous multicarrier codedivision multipleaccess (MCCDMA) communications in order to provide zero interference performance. When each complementary code is arranged to be a matrix, the peaktomean envelope power ratio (PMEPR) of the CCCMCCDMA system is determined by the column sequences of the complementary matrices. The existing CCC have the column sequence PMEPR of M, where M denotes the number of subcarriers in a CCCMCCDMA system. In practice, M is generally large and a PMEPR approaching this value is unacceptable. To solve this problem, a new class of CCC using generalized Boolean functions and with a column sequence PMEPR of at most 2 is proposed in this paper.
Sequence Design for Cognitive CDMA Communications under Arbitrary Spectrum Hole Constraint
"... To support interferencefree quasisynchronous codedivision multipleaccess (QSCDMA) communication with low spectral density profile in a cognitive radio (CR) network, it is desirable to design a set of CDMA spreading sequences with zerocorrelation zone (ZCZ) property. However, traditional ZCZ se ..."
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To support interferencefree quasisynchronous codedivision multipleaccess (QSCDMA) communication with low spectral density profile in a cognitive radio (CR) network, it is desirable to design a set of CDMA spreading sequences with zerocorrelation 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 “quasiZCZ ” CR sequences) which displays zero crosscorrelation and nearzero autocorrelation zone property under arbitrary spectrum hole constraint is presented in this paper. Furthermore, a novel algorithm is proposed to jointly optimize the peaktoaverage power ratio (PAPR) and the periodic autocorrelations of the proposed quasiZCZ CR sequences. Simulations show that they give rise to singleuser biterrorrate performance in CRCDMA systems which outperform traditional noncontiguous multicarrier CDMA and transform domain communication systems; they also lead to CRCDMA systems which are more resilient than noncontiguous OFDM systems to spectrum sensing mismatch, due to the wideband spreading.
On the Perfect Cyclically Conjugated Even and Odd Periodic Autocorrelation Properties of Quaternary Golay Sequences
"... A sequence is called perfect if its autocorrelation function is a delta function. In this paper, we give a new definition of autocorrelation function: generalized even and odd periodic autocorrelation, and generalized even and odd periodic cyclically conjugated autocorrelation. In particular, we stu ..."
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A sequence is called perfect if its autocorrelation function is a delta function. In this paper, we give a new definition of autocorrelation function: generalized even and odd periodic autocorrelation, and generalized even and odd periodic cyclically conjugated autocorrelation. In particular, we study a special case of autocorrelation function called cyclically conjugated autocorrelation function. As a result, we present several classes of perfect cyclically conjugated even periodic and odd periodic autocorrelation of quaternary Golay sequences. We also considered such perfect property for 4qQAM Golay sequences, q ≥ 2 being an integer. Those proposed sequences could be used for synchronization and detection if the time delay is known. Index Terms. Golay sequence, quadrature amplitude modulation (QAM), cyclically conjugated even periodic autocorrelation, cyclically conjugated odd periodic autocorrelation. 1
Optimal OddLength Binary ZComplementary Pairs
, 2013
"... A pair of sequences is called a Golay complementary pair (GCP) if their aperiodic autocorrelation sums are zero for all outofphase time shifts. Existing known binary GCPs only have evenlengths in the form of 21026 (where ; ;
are nonnegative integers). To fill the gap left by the oddlengths, ..."
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A pair of sequences is called a Golay complementary pair (GCP) if their aperiodic autocorrelation sums are zero for all outofphase time shifts. Existing known binary GCPs only have evenlengths in the form of 21026 (where ; ;
are nonnegative integers). To fill the gap left by the oddlengths, we investigate the optimal oddlength binary pairs which display the closest correlation property to that of GCPs. Our criteria of “closeness ” is that each pair has the maximum possible zerocorrelation zone (ZCZ) width and minimum possible outofzone aperiodic autocorrelation sums. Such optimal pairs are called optimal oddlength binary Zcomplementary pairs (OBZCP) in this paper. We show that each optimal OBZCP has maximum ZCZ width of (N+1)=2, and minimum outofzone aperiodic sum magnitude of 2, where N denotes the sequence length (odd). Systematic constructions of such optimal OPZCPs are proposed by insertion and deletion of certain binary GCPs, which settle the 2011 LiFanTangTu open problem positively. The proposed optimal OBZCPs may serve as a replacement for GCPs in many engineering applications where odd sequence lengths are preferred. In addition, they give rise to a new family of basetwo almost difference families (ADF) which are useful in studying partially balanced incomplete block design (BIBD).
FractionalDelayResilient Receiver Design for InterferenceFree MCCDMA Communications Based on Complete Complementary Codes
"... Complete complementary codes (CCC) refer to a set of twodimensional matrices which have zero nontrivial aperiodic auto and cross correlation sums. A modern application of CCC is in interferencefree multicarrier codedivision multipleaccess (MCCDMA) communications. In this paper, we first show ..."
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Complete complementary codes (CCC) refer to a set of twodimensional matrices which have zero nontrivial aperiodic auto and cross correlation sums. A modern application of CCC is in interferencefree multicarrier codedivision multipleaccess (MCCDMA) communications. In this paper, we first show that in asynchronous “fractionaldelay” uplink channels, CCCMCCDMA systems suffer from orthogonality loss which may lead to huge interference increase when a conventional correlator based receiver is deployed. Then, by exploiting the correlation properties of CCC, we present a fractionaldelayresilient receiver which is comprised of a chipspaced correlating array. Analysis and simulations validate the interferencefree achievability of the proposed CSCA receiver in strong interference scenarios.