Speaker identification and verification using Gaussian mixture speaker models

Non-Gaussian statistical signal processing is important when signals and/or noise deviate from the ideal Gaussian model. Stable distributions are among the most important non-Gaussian models. They share defining characteristics with the Gaussian distribution, such as the stability property and central limit theorems, and in fact include the Gaussian distribution as a limiting case. To help engineers better understand the stable models and develop methodologies for their applications in signal processing. A tutorial review of the basic characteristics of stable distributions and stable signal processing is presented. The emphasis is on the differences and similarities between stable signal processing methods based on fractional lower-order moments and Gaussian signal processing methods based on second-order moments. >

Signal processing with fractional lower order moments: stable processes and their applications

Due to the broadcast nature of radio propagation, the wireless air interface is open and accessible to both authorized and illegitimate users. This completely differs from a wired network, where communicating devices are physically connected through cables and a node without direct association is unable to access the network for illicit activities. The open communications environment makes wireless transmissions more vulnerable than wired communications to malicious attacks, including both the passive eavesdropping for data interception and the active jamming for disrupting legitimate transmissions. Therefore, this paper is motivated to examine the security vulnerabilities and threats imposed by the inherent open nature of wireless communications and to devise efficient defense mechanisms for improving the wireless network security. We first summarize the security requirements of wireless networks, including their authenticity, confidentiality, integrity, and availability issues. Next, a comprehensive overview of security attacks encountered in wireless networks is presented in view of the network protocol architecture, where the potential security threats are discussed at each protocol layer. We also provide a survey of the existing security protocols and algorithms that are adopted in the existing wireless network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term evolution (LTE) systems. Then, we discuss the state of the art in physical-layer security, which is an emerging technique of securing the open communications environment against eavesdropping attacks at the physical layer. Several physical-layer security techniques are reviewed and compared, including information-theoretic security, artificial-noise-aided security, security-oriented beamforming, diversity-assisted security, and physical-layer key generation approaches. Since a jammer emitting radio signals can readily interfere with the legitimate wireless users, we also introduce the family of various jamming attacks and their countermeasures, including the constant jammer, intermittent jammer, reactive jammer, adaptive jammer, and intelligent jammer. Additionally, we discuss the integration of physical-layer security into existing authentication and cryptography mechanisms for further securing wireless networks. Finally, some technical challenges which remain unresolved at the time of writing are summarized and the future trends in wireless security are discussed.

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A Survey on Wireless Security: Technical Challenges, Recent Advances, and Future Trends

Introduction A fundamental objective of cryptography is to enable two persons to communicate over an insecure channel (a public channel such as the internet) in such a way that any other person is unable to recover their message (called the plaintext ) from what is sent in its place over the channel (the ciphertext ). The transformation of the plaintext into the ciphertext is called encryption , or enciphering. Encryption-decryption is the most ancient cryptographic activity (ciphers already existed four centuries b.c.), but its nature has deeply changed with the invention of computers, because the cryptanalysis (the activity of the third person, the eavesdropper, who aims at recovering the message) can use their power. The encryption algorithm takes as input the plaintext and an encryption key K E , and it outputs the ciphertext. If the encryption key is secret, then we speak of conventional cryptography , of private key cryptography , or of symmetric cryptography . In practice, the principle of conventional cryptography relies on the sharing of a private key between the sender of a message (often called Alice in cryptography) and its receiver (often called Bob). If, on the contrary, the encryption key is public, then we speak of public key cryptography . Public key cryptography appeared in the literature in the late 1970s.

/pdf/boolean-models-and-methods-in-mathematics-computer-science-3vbrnbyptk.pdf

Boolean Models and Methods in Mathematics, Computer Science, and Engineering: Boolean Functions for Cryptography and Error-Correcting Codes

We study the relation between cognitive abilities and stockholding using the recent Survey of Health, Ageing and Retirement in Europe (SHARE), which has detailed data on wealth and portfolio composition of individuals aged 50 in 11 European countries and three indicators of cognitive abilities: mathematical, verbal fluency, and recall skills We find that the propensity to invest in stocks is strongly associated with cognitive abilities, for both direct stock market participation and indirect participation through mutual funds and retirement accounts Since the decision to invest in less information-intensive assets (such as bonds) is less strongly related to cognitive abilities, we conclude that the association between cognitive abilities and stockholding is driven by information constraints, rather than by features of preferences or psychological traits

/pdf/cognitive-abilities-and-portfolio-choice-17r2n1q80y.pdf

Cognitive Abilities and Portfolio Choice

We present three unconventional approaches to keying variable management. The first approach is based on using a public key cryptosystem (PKC) that is breakable in short, but on average less, time than it takes to set up an ultrawide bandwidth modem that is then used to transport a keying variable for a classical cryptosystem. The second concept proposes using the characteristics of an urban UHF radio channel, determined by mutual sounding, as the cryptovariable. The third concept encourages research into ill-conditioned problems as potentially fruitful ground for PKCs not based on finite field arithmetic. >

Unconventional cryptographic keying variable management

Preface 1 Kronecker Matrix Algebra 2 A Hadamard Matrix 3 The Sylvester-Hadamard Matrix of Rank 2n 4 The Eigenvalues of Hn 5 The Eigenvectors of Hn 6 Other Constructions of Hn 7 The Hadamard Transform and its Fast Implementation 8 Use of the 1-D Hadamard Transform in the Computation of a 2-D Hadamard Transform 9 The Fast Fourier Transform and the Hadamard Transform 10 Computational Structures 11 Efficient Hadamard Transform Domain Computation 12 The Hadamard Transform in Statistics 13 The Hadamard Transform and Error-Correction Coding 14 Boolean Functions 15 Spectrally Preconditioned Threshold Logic 16 Synthesis of Bent Functions 17 The m-Sequence 18 Composite Sequences 19 The Thue-Morse Sequence 20 Signal Representation 21 A New Hadamard Basis and Its Implication for Signaling 22 A Stochastic Operator Field 23 A Naturalness Preserving Transform References Index

Hadamard Matrix Analysis and Synthesis: With Applications to Communications and Signal/Image Processing

This paper presents a fast algorithm for computing the reliability of a communication network when each link has the same probability of success. The computational complexity of existing algorithms increases exponentially as the number of links increases. Our algorithm is based on combinatorics and we conclude, for the case when links have the same survival probabilities, that the computational complexity grows subexponentially as the number of links increases. Furthermore, the algorithm is mostly algebraic in nature.

Fast algorithm for computing the reliability of a communication network

This book presents a systematic, comprehensive treatment of analog, discrete signal analysis and synthesis and an introduction to analog communication theory. The material is divided into five parts. The first part (Chapters 1-3) is mathematically oriented and deals with continuous-time (analog) signals. The second part (Chapters 4-5) is again mathematically based and deals with Fourier transforms, Hartley transforms, Laplace and Hilbert transforms. The third part (Chapters 6-7) presents basic system analysis, approximations, and analog filter circuits using op-amps. The fourth part (Chapters 8-9) deals with discrete signals, fast algorithms and digital filters. The fifth part deals with an introduction to analog communication systems.

R. K. Rao Yarlagadda

Papers

Unconventional cryptographic keying variable management

Hadamard Matrix Analysis and Synthesis: With Applications to Communications and Signal/Image Processing

Fast algorithm for computing the reliability of a communication network

Analog and Digital Signals and Systems

Hadamard matrix analysis and synthesis