A simple method for approximation of all-pole recursive digital filters, directly in digital domain, is described. Transfer function of these filters, referred to as Ultraspherical filters, is controlled by order of the Ultraspherical polynomial, ν. Parameter ν, restricted to be a non-negative real number (ν ≥ 0), controls ripple peaks in the passband of the magnitude response and enables a tra...

Fractional delay FIR filters design method based on the differential evolution algorithm is presented. Differential evolution is an evolutionary algorithm for solving a global optimization problems in the continuous search space. In the proposed approach, an evolutionary algorithm is used to determine the coefficients of a fractional delay FIR filter based on the Farrow structure. Basic differe...

Voice source analysis and modelling has played a key role in important speech applications such as speech recognition, speech synthesis and speaker recognition. This work presents a robust algorithm for glottal closure detection and a novel set of voice source features for speaker recognition. In the rst part of the dissertation the DYPSA algorithm is developed for detecting glottal closure ins...

This paper presents a ray tracing technique to predict path loss and delay spread in buildings. A computer program to predict radio propagation in buildings based on site-specific information such as wall locations and building materials is described. Using geometrical optics-based assumptions, rays are traced in three dimensions from a transmitter location. Line-of-sight, specularly transmitte...

ad hoc networks are multi-hop wireless networks without a pre-installed infrastructure. such networks are widely used in military applications and in emergency situations as they permit the establishment of a communication network at very short notice with a very low cost. video is very sensitive for packet loss and wireless ad-hoc networks are error prone due to node mobility and weak links. h...

This paper provides a preliminary investigation of the effect of abrupt round-trip variations on the performance of different versions of TCP. It is shown that end-toend goodput of a bulk TCP transfer can be severely limited by variations in RTT primarily due to the non-adaptiveness of TCP’s timeout estimation and fast recovery thresholds. The paper proposes a model for evaluating the performan...

We show that the difficulty of cloaking is fundamentally limited by delay-loss and delay-bandwidth limitations that worsen as the size of the object to be cloaked increases relative to the wavelength, using a simple model of ground-plane cloaking. These limitations must be considered when scaling experimental cloaking demonstrations up from wavelength-scale objects.