Results 11  20
of
73
How do more Golay sequences arise
 IEEE Trans. Inform. Theory
"... In 1999 Davis and Jedwab gave a direct construction of Golay complementary sequences over Z 2 h of length 2 m. Recently Li and Chu found 1024 more quaternary Golay complementary sequences of length 16, that cannot be obtained by the direct construction, using exhaustive computer enumeration. It is s ..."
Abstract

Cited by 9 (3 self)
 Add to MetaCart
In 1999 Davis and Jedwab gave a direct construction of Golay complementary sequences over Z 2 h of length 2 m. Recently Li and Chu found 1024 more quaternary Golay complementary sequences of length 16, that cannot be obtained by the direct construction, using exhaustive computer enumeration. It is shown how these sequences arise from interleaving and concatenation of two classes of Golay complementary sequences given as an example by Davis and Jedwab. These examples spawn new Golay sequences over Z 2 h of length 2 m for all h ≥ 2 and m ≥ 4.
A Framework for the Construction of Golay Sequences
, 2006
"... ... normal form for m! · 2 h(m+2) ordered Golay pairs of length 2 m over Z 2 h, involving m!/2 · 2 h(m+1) Golay sequences. In 2005 Li and Chu unexpectedly found an additional 1024 length 16 quaternary Golay sequences. Fiedler and Jedwab showed in 2006 that these new Golay sequences exist because of ..."
Abstract

Cited by 9 (3 self)
 Add to MetaCart
... normal form for m! · 2 h(m+2) ordered Golay pairs of length 2 m over Z 2 h, involving m!/2 · 2 h(m+1) Golay sequences. In 2005 Li and Chu unexpectedly found an additional 1024 length 16 quaternary Golay sequences. Fiedler and Jedwab showed in 2006 that these new Golay sequences exist because of a “crossover” of the aperiodic autocorrelation function of certain quaternary length 8 sequences belonging to Golay pairs, and that they spawn further new quaternary Golay sequences and pairs of length 2 m for m> 4 under Budiˇsin’s 1990 iterative construction. The total number of Golay sequences and pairs spawned in this way is counted, and their algebraic normal form is given explicitly. A framework of constructions is derived in which Turyn’s 1974 product construction, together with several variations, plays a key role. All previously known Golay sequences and pairs of length 2 m over Z 2 h can be obtained directly in explicit algebraic normal form from this framework. Furthermore, additional quaternary Golay sequences and pairs of length 2 m are produced that cannot be obtained from any other known construction. The framework generalizes readily to lengths that are not a power of 2, and to alphabets other than Z 2 h.
PAPR and Other Measures for OFDM Systems with Nonlinearity
 5TH INTERNATIONAL SYMPOSIUM ON WIRELESS PERSONAL MULTIMEDIA COMMUNICATIONS, VOL.1
, 2002
"... In this paper, we discuss the effects of nonlinearity on the performance in transmission of OFDM signals. Furthermore, we study measures related to nonlinearities, such as PAPR (PeaktoAveragePowerRatio), with respect to their ability to correctly predict the effect of a nonlinearity in an OFDM s ..."
Abstract

Cited by 8 (0 self)
 Add to MetaCart
In this paper, we discuss the effects of nonlinearity on the performance in transmission of OFDM signals. Furthermore, we study measures related to nonlinearities, such as PAPR (PeaktoAveragePowerRatio), with respect to their ability to correctly predict the effect of a nonlinearity in an OFDM system. We also propose new measures for signal distortion in nonlinear systems. The performance of the measures are studied using several examples.
Golay complementary array pairs
 Designs, Codes and Cryptography
"... Constructions and nonexistence conditions for multidimensional Golay complementary array pairs are reviewed. A construction for a ddimensional Golay array pair from a (d + 1)dimensional Golay array pair is given. This is used to explain and expand previously known constructive and nonexistence re ..."
Abstract

Cited by 7 (4 self)
 Add to MetaCart
(Show Context)
Constructions and nonexistence conditions for multidimensional Golay complementary array pairs are reviewed. A construction for a ddimensional Golay array pair from a (d + 1)dimensional Golay array pair is given. This is used to explain and expand previously known constructive and nonexistence results in the binary case.
Constant Envelope OFDM
, 2008
"... This paper describes a transformation technique aimed at solving the peaktoaverage power ratio (PAPR) problem associated with OFDM (orthogonal frequencydivision multiplexing). Constant envelope OFDM (CEOFDM) transforms the OFDM signal, by way of phase modulation, to a signal designed for effici ..."
Abstract

Cited by 7 (1 self)
 Add to MetaCart
This paper describes a transformation technique aimed at solving the peaktoaverage power ratio (PAPR) problem associated with OFDM (orthogonal frequencydivision multiplexing). Constant envelope OFDM (CEOFDM) transforms the OFDM signal, by way of phase modulation, to a signal designed for efficient power amplification. At the receiver, the inverse transformation—phase demodulation—is applied prior to the conventional OFDM demodulator. The performance of CEOFDM is analyzed in additive white Gaussian noise (AWGN) and fading channels. CEOFDM is shown to achieve good performance in dense multipath with the use of cyclic prefix transmission in conjunction with a frequencydomain equalizer (FDE). By way of computer simulation and hardware realization, CEOFDM is shown to compare favorably to conventional OFDM.
Analysis of clipping noise and tonereservation algorithms for peak reduction in OFDM systems,” submitted to IEEE Trans. Veh. Technol., 2006. ©142440357X/06/$20.00 2006 IEEE This full text paper was peer reviewed at the direction of
 in the IEEE GLOBECOM 2006 proceedings. Authorized licensed use limited to: UNIVERSITY OF ALBERTA. Downloaded on December 21, 2009 at 18:01 from IEEE Xplore. Restrictions apply
"... Abstract—Orthogonal frequency division multiplexing (OFDM) suffers from a high peaktoaverage power ratio (PAR). Tone reservation is a popular PAR reduction technique that uses a set of reserved tones to design a peakcanceling signal. In a previous paper by Krongold and Jones, an activeset appro ..."
Abstract

Cited by 6 (3 self)
 Add to MetaCart
Abstract—Orthogonal frequency division multiplexing (OFDM) suffers from a high peaktoaverage power ratio (PAR). Tone reservation is a popular PAR reduction technique that uses a set of reserved tones to design a peakcanceling signal. In a previous paper by Krongold and Jones, an activeset approach was developed to efficiently compute the peakcanceling signal. In this paper, we consider the use of clipping noise, which is generated when the OFDM signal is clipped at a predefined threshold, to design the peakcanceling signal. To this end, the clipping noise is analyzed as a series of parabolic pulses under tonereservation constraints. The singlepulse case and the multiplepulse case are treated. The analysis explains peak regrowth and the constancy of the clipping noise power spectrum over the whole OFDM band. Moreover, the clipping noise at the end of several clipping and filtering iterations is shown to be approximately proportional to that generated in the first iteration. The constant of proportionality is estimated via the levelcrossing theory for high clipping thresholds. Using this analysis, a constantscaling algorithm and an adaptivescaling algorithm are proposed for tone reservation. These algorithms scale the filtered firstiteration clipping noise to compensate for peaks that are above the threshold. The simulation results show that the proposed algorithms achieve a larger peak reduction and lower complexity than the activeset algorithm. Index Terms—Orthogonal frequency division multiplexing (OFDM), peak reduction, scaling, time and frequency domain analysis, tone reservation.
New Constructions of General QAM Golay Complementary Sequences
, 2012
"... There have been five constructions (Case I to Case V) of 64QAM Golay complementary sequences (GCSs), of which the Case IV and Case V constructions were identified by Chang, Li, and Hirata in 2010. The Generalized Cases IIII constructions for 4qQAM (q ≥ 1) GCSs were additionally proposed by Li. In ..."
Abstract

Cited by 6 (2 self)
 Add to MetaCart
There have been five constructions (Case I to Case V) of 64QAM Golay complementary sequences (GCSs), of which the Case IV and Case V constructions were identified by Chang, Li, and Hirata in 2010. The Generalized Cases IIII constructions for 4qQAM (q ≥ 1) GCSs were additionally proposed by Li. In this paper, the Generalized Case IV and Generalized Case V constructions for 4qQAM (q> = 3) GCSs are proposed using selected Gaussian integer pairs, each of which contains two distinct Gaussian integers with identical magnitude and which are not conjugate with each other.
Turbocoded OFDM transmission over nonlinear channel
, 2004
"... In this paper, deliberate level clipping and Turbocoding are combined to achieve an Orthogonal Frequency Division Multiplexing (OFDM) transmission system with a low PeaktoAverage power Ratio (PAR) and a good performance. Using the linear approximation technique, we first modify the metric computa ..."
Abstract

Cited by 5 (0 self)
 Add to MetaCart
In this paper, deliberate level clipping and Turbocoding are combined to achieve an Orthogonal Frequency Division Multiplexing (OFDM) transmission system with a low PeaktoAverage power Ratio (PAR) and a good performance. Using the linear approximation technique, we first modify the metric computation for the Turbodecoding in order to consider the distortion effects of the nonlinearity, caused by the Cartesian clipping. The linear approximation of the nonlinear device is based on the Minimum Mean Square Error (MMSE) criterion. By exploiting the linear model, the receiver calculates a modified metric considering the effects of the nonlinearity. Also, this paper introduces a modified Turbodecoder which simultaneously performs the data estimation and signal reconstruction. In other words, the Turbodecoder iteratively recovers the clipped signal by using the estimated data, and then improves the data estimation by using the newly recovered signal. Numerical results are presented showing an improvement in the performance of the OFDM transmission system over the nonlinear channel, an increase in the efficiency of the High Power Amplifier (HPA), and/or an expansion of the transmitter coverage area.
Peaktoaverage power ratio reduction of OFDM systems using cross entropy method
 in 17th Int. Conf. on Wireless Commun
, 2005
"... copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis, and except as herein before provided, neither the thesis nor any substantial ..."
Abstract

Cited by 5 (4 self)
 Add to MetaCart
(Show Context)
copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis, and except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatever without the author’s prior written permission.
A Tighter Correlation Lower Bound for QuasiComplementary Sequence Sets
"... Levenshtein improved the famous Welch bound on aperiodic correlation for binary sequences by utilizing some properties of the weighted mean square aperiodic correlation. Following Levenshtein’s idea, a new correlation lower bound for quasicomplementary sequence sets (QCSSs) over the complex roots o ..."
Abstract

Cited by 5 (5 self)
 Add to MetaCart
Levenshtein improved the famous Welch bound on aperiodic correlation for binary sequences by utilizing some properties of the weighted mean square aperiodic correlation. Following Levenshtein’s idea, a new correlation lower bound for quasicomplementary sequence sets (QCSSs) over the complex roots of unity is proposed in this paper. The derived lower bound is shown to be tighter than the Welch bound for QCSSs when the set size is greater than some value. The conditions for meeting the new bound with equality are also investigated.