New Methods to Construct Golay Complementary Sequences Over the QAMQAM Constellation

In this paper, based on binary Golay complementary sequences, we propose some methods to construct Golay complementary sequences of length $2^n$ for integer n, over the $M^2$-$QAM$ constellation and $2M$-$Q$-$PAM$ constellations, where $M=2^m$ for integer $m$. A method to judge whether a sequence constructed using the new general offset pairs over the $QAM$ constellation is Golay complementary sequence is proposed. Base on this judging rule, we can construct many new Golay complementary sequences. In particular, we study Golay complementary sequences over $16$-$QAM$ constellation and $64$-$QAM$ constellation,many new Golay complementary sequences over these constellations have been found

Quadrature amplitude modulated codes with low peak-to-mean envelope power ratio for orthogonal frequency division multiplexing applications

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 83).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Orthogonal Frequency Division Multiplexing (OFDM) has been adopted as the modulation technique for many of the next generation wireless broadband multimedia communications systems, for example, Digital Audio Broadcasting (DAB), terrestrial Digital Video Broadcasting (DVB), and the wireless local area network (LAN) standards HIPERLAN/2, and IEEE 802.11a. One problem inherent in plain vanilla OFDM is that its signal envelope fluctuates greatly with very high power peaks, necessitating the use of inefficient and complex linear power amplifiers. Solutions to the high peak-to-mean envelope power ratio (PMEPR) problem include signal processing techniques such as clipping, peak windowing, and peak cancellation, as well as coding techniques, i.e. using codes to ensure that only those OFDM signals with low PMEPR are transmitted. It is well known that using codewords generated by mapping binary Golay complementary sequences into BPSK yields OFDM signals with low PMEPR. Frank, Sivaswamy, and others have extended the results of Golay from binary phase shift keying (BPSK) to other PSK constellations. Recently, Davis and Jedwab presented a code structure for these PSK complementary sequences using cosets of first-order Reed-Muller codes in second-order Reed-Muller codes. This yielded OFDM codes using PSK modulation which could be encoded and decoded using well-understood algorithms for Reed-Muller codes. This thesis investigates the properties of quadrature amplitude modulated (QAM) OFDM signals with low PMEPR, focusing in particular on signals based on 4-QAM and 16-QAM constellations. We construct and prove new code structures for sequences in 4-QAM and 16-QAM that result OFDM signals with low PMEPR. Many practical implementations of OFDM use QAM constellations instead of PSK constellations. Thus the codes presented could be used to design pilot symbols for actual OFDM systems, as well as be employed in practical OFDM applications requiring both low PMEPR as well as low computational complexity.by Chan Vee Chong.S.M

Intelligent OFDM telecommunication system. Part 1. Model of complex and quaternion systems

In this paper, we aim to investigate the superiority and practicability of many-parameter transforms (MPTs) from the physical layer security (PHY-LS) perspective. We propose novel Intelligent OFDM-telecommunication systems based on complex and quaternion MPTs. The new systems use inverse MPT (IMPT) for modulation at the transmitter and MPT for demodulation at the receiver. The purpose of employing the MPT is to improve: 1) the PHY-LS of wireless transmissions against to the wide-band anti-jamming and anti-eavesdropping communication; 2) the bit error rate (BER) performance with respect to the conventional OFDM-TCS; 3) the peak to average power ratio (PAPR). Each MPT depends on finite set of independent parameters (angles). When parameters are changed, many-parametric transform is also changed taking form of a set known (and unknown) orthogonal (or unitary) transforms. For this reason, the concrete values of parameters are specific "key" for entry into OFDM-TCS. Vector of parameters belong to multi-dimension torus space. Scanning of this space for find out the "key" (the concrete values of parameters) is hard problem. MPT has the form of the product of the Jacobi rotation matrixes and it describes a fast algorithm for MPT. The main advantage of using MPT in OFDM TCS is that it is a very flexible anti-eavesdropping and anti-jamming Intelligent OFDM TCS. To the best of our knowledge, this is the first work that utilizes the MPT theory to facilitate the PHY-LS through parameterization of unitary transforms. © 2019 IOP Publishing Ltd. All rights reserved

On multicarrier signals where the PMEPR of a random codeword is asymptotically log n

Multicarrier signals exhibit a large peak-to-mean envelope power ratio (PMEPR). In this correspondence, without using a Gaussian assumption, we derive lower and upper probability bounds for the PMEPR distribution when the number of subcarriers n is large. Even though the worst case PMEPR is of the order of n, the main result is that the PMEPR of a random codeword C=(c/sub 1/,...,c/sub n/) is logn with probability approaching one asymptotically, for the following three general cases: i) c/sub i/'s are independent and identically distributed (i.i.d.) chosen from a complex quadrature amplitude modulation (QAM) constellation in which the real and imaginary part of c/sub i/ each has i.i.d. and even distribution (not necessarily uniform), ii) c/sub i/'s are i.i.d. chosen from a phase-shift keying (PSK) constellation where the distribution over the constellation points is invariant under /spl pi//2 rotation, and iii) C is chosen uniformly from a complex sphere of dimension n. Based on this result, it is proved that asymptotically, the Varshamov-Gilbert (VG) bound remains the same for codes with PMEPR of less than logn chosen from QAM/PSK constellations