Large Zero Autocorrelation Zone of Golay Sequences and 4q4^q-QAM Golay Complementary Sequences

Sequences with good correlation properties have been widely adopted in modern communications, radar and sonar applications. In this paper, we present our new findings on some constructions of single $H$-ary Golay sequence and $4^q$-QAM Golay complementary sequence with a large zero autocorrelation zone, where $H\ge 2$ is an arbitrary even integer and $q\ge 2$ is an arbitrary integer. Those new results on Golay sequences and QAM Golay complementary sequences can be explored during synchronization and detection at the receiver end and thus improve the performance of the communication system

Sequences design for OFDM and CDMA systems

With the emergence of multi-carrier (MC) orthogonal frequency division multiplexing (OFDM) scheme in the current WLAN standards and next generation wireless broadband standards, the necessitation to acquire a method for combating high peak to average power ratio (PMEPR) becomes imminent. In this thesis, we will explore various sequences to determine their PMEPR behaviours, in hopes to find some sequences which could potentially be suitable for PMEPR reduction control under MC system settings. These sequences include $m$ sequences, Sidelnikov sequences, new sequences, Golay sequences, FZC sequences and Legendre sequences. We will also examine the merit factor properties of these sequences, and then we will derive a bound between PMEPR and merit factor. Moreover, in the design of code division multiple access (CDMA) spreading sequence sets, it is critical that each sequence in the set has low autocorrelations and low cross-correlation with other sequences in the same set. In the thesis, we will present a class of GDJ Golay sequences which contains a large zero autocorrelation zone (ZACZ), which could satisfy the low autocorrelation requirement. This class of Golay sequences could potentially be used to construct new CDMA spreading sequence sets

Vibroseis encoding

The FM signals, called sweeps, used in the Vibroseis method of seismic exploration show a considerable amount of energy in the sidelobes after correlation detection. These sidelobes represent signal generated noise and if not kept low in amplitude they miggit mask subsequent reflections, thereby reducing the detection capability of the Vibroseis system. The purpose of this research has been to investigate new coded signal design techniques for the use with Vibroseis, in order to achieve sidelobe suppression. Some of the codes examined have already been known to radar and communication theory, whilst some codes are original developments of this research exercise. Binary and quaternary complementary series are found to be especially suitable for a Vibroseis encoding technique. A new and simple algorithm for the generation of quaternary series from known binary complementary sequences is given and the concept of correlation matrices is introduced to complementary series, permitting signal design in the detection window. The encoded Vibroseis input signals were tested on a computer and showed perfect sidelobe suppression a certain distance away from the main compressed pulse, when detected by a matched filter. Field tests with the coded signals were conducted, taking advantage of a computerized Vibroseis field system. The tests showed promising results. However, it became clear that the vibrator control devices will have to be adjusted to the transmission of such sophisti cated signals, in order to allow substantially better results than in the conventional Vibroseis system. A ‘Continuous Vibroseis Transmission System’ is suggested, transmitting energy during the normal listening period. Such a system has been developed witht h help of so-called ‘Mutually-Orthogonal-Complementay Sets of Sequences’ and although not yet practically tested its anticipated advantages and disadvantages are described. Finally, ‘Predistortion’ as a method of Vibroseis signal design is examined. Providing the correct predestortion parameters are chosen, the signal-to-correlation noise ratio an be increased. A spectrum whitening effect observed an addition of selected perdistorted sweeps can be of advantage in a quaternary comlementary coded Viboseis system, permitting an optimal wavelet design in the detection window

Cross Z-Complementary Pairs for Optimal Training in Spatial Modulation Over Frequency Selective Channels

The contributions of this article are twofold: Firstly, we introduce a novel class of sequence pairs, called “cross Z-complementary pairs (CZCPs),” each displaying zero-correlation zone (ZCZ) properties for both their aperiodic autocorrelation sums and crosscorrelation sums. Systematic constructions of perfect CZCPs based on selected Golay complementary pairs (GCPs) are presented. Secondly, we point out that CZCPs can be utilized as a key component in designing training sequences for broadband spatial modulation (SM) systems. We show that our proposed SM training sequences derived from CZCPs lead to optimal channel estimation performance over frequency-selective channels

A Direct Construction of Prime-Power-Length Zero-Correlation Zone Sequences for QS-CDMA System

In recent years, zero-correlation zone (ZCZ) sequences are being studied due to their significant applications in quasi-synchronous code division multiple access (QS-CDMA) systems and other wireless communication domains. However, the lengths of most existing ZCZ sequences are limited, and their parameters are not flexible, which are leading to practical limitations in their use in QS-CDMA and other communication systems. The current study proposes a direct construction of ZCZ sequences of prime-power length with flexible parameters by using multivariable functions. In the proposed construction, we first present a multivariable function to generate a vector with specific properties; this is further used to generate another class of multivariable functions to generate the desired $(p^t,(p-1)p^n,p^{n+t+1})$-ZCZ sequence set, where $p$ is a prime number, $t,n$ are positive integers, and $t\leq n$. The constructed ZCZ sequence set is optimal for the binary case and asymptotically optimal for the non-binary case by the \emph{Tang-Fan-Matsufuji} bound. Moreover, a relation between the second-order cosets of first-order generalized Reed-Muller code and the proposed ZCZ sequences is also established. The proposed construction of ZCZ sequences is compared with existing constructions, and it is observed that the parameters of this ZCZ sequence set are a generalization of that of in some existing works. Finally, the performance of the proposed ZCZ-based QS-CDMA system is compared with the Walsh-Hadamard and Gold code-based QS-CDMA system