Abstract. Most feature extraction techniques involve in their primary stage a Discrete Fourier Tr... more Abstract. Most feature extraction techniques involve in their primary stage a Discrete Fourier Transform (DFT) of consecutive, short, overlapping windows. The spectral resolution of the DFT representation is uniform and is given by Δf=2π/Ν where N is the length of the window The present paper investigates the use of non-uniform rate frequency sampling, varying as a function of the spectral characteristics of each frame, in the context of Automatic Speech Recognition. We are motivated by the non-uniform spectral sensitivity of human hearing and the necessity for a feature extraction technique that autofocuses on most reliable parts of the spectrum in noisy cases. 1
ABSTRACT In this paper we calculate both call and burst blocking probabilities of ON–OFF traffic ... more ABSTRACT In this paper we calculate both call and burst blocking probabilities of ON–OFF traffic sources with retrials. Calls of service-classes arrive to a single link according to a Poisson process and compete for the available link bandwidth under the complete sharing policy. Blocked calls may immediately retry one or more times to enter the system, with reduced bandwidth and increased mean service time requirements. Call blocking occurs when a call cannot enter the system with its last bandwidth requirement, due to lack of bandwidth. Accepted calls enter the system via state ON and may alternate between states ON and OFF, or remain always in state ON. When a call is transferred to state OFF it releases the bandwidth held in state ON, so that this bandwidth becomes available to new arriving calls. When a call tries to return to state ON, it re-requests its bandwidth. If it is available a new ON-period (burst) begins. Otherwise burst blocking occurs and the call remains in state OFF. The proposed ON–OFF retry models do not have a product form solution and therefore the calculation of call and burst blocking probability is based on approximate formulas. The formulas we propose for the call blocking probabilities are recursive, whereas for the burst blocking probabilities are robust. Simulation results validate our analytical methodology. For further evaluation, the results of the ON–OFF retry models are compared with those of the ON–OFF model without retrials. We also discuss the extension of the proposed formulas in the case of a fixed-routing network.
We consider the fair bandwidth allocation problem of ABR calls by a Connection Admission Controll... more We consider the fair bandwidth allocation problem of ABR calls by a Connection Admission Controller (CAC) at call setup. Its general solution is given by applying the "max-min fairness allocation policy". Extensions of this policy take into account the Minimum Cell Rate (MCR) and the Peak Cell Rate (PCR) traffic description parameters, which are essential for ABR. These extensions are distinguished according to the existence or non-existence of weights in the policy. The weights may be defined independent of MCR or dependent on MCR. In this paper firstly we present a linear programming model, which describes in a parametric way both weighted and unweighted bandwidth allocation policies for ABR services. Because of the parametric nature of the LP model, it can be easily extended in order to take into account various bandwidth allocation policies. Secondly, we propose an unweighted fair bandwidth allocation policy in which ABR calls are grouped in categories, according to th...
ABSTRACT The present paper reports on a novel technique that links the basic concepts of multi-ba... more ABSTRACT The present paper reports on a novel technique that links the basic concepts of multi-band based Automatic Speech Recognition (ASR) and Missing Feature Theory (MFT). In the multi-band paradigm the frequency spectrum is partitioned in narrow bands and processed independently. In the context of MFT, the stochastic framework of continuous density Hidden Markov Models (HMMs) is adapted to handle time frequency regions corrupted by noise.
Abstract. Most feature extraction techniques involve in their primary stage a Discrete Fourier Tr... more Abstract. Most feature extraction techniques involve in their primary stage a Discrete Fourier Transform (DFT) of consecutive, short, overlapping windows. The spectral resolution of the DFT representation is uniform and is given by Δf=2π/Ν where N is the length of the window The present paper investigates the use of non-uniform rate frequency sampling, varying as a function of the spectral characteristics of each frame, in the context of Automatic Speech Recognition. We are motivated by the non-uniform spectral sensitivity of human hearing and the necessity for a feature extraction technique that autofocuses on most reliable parts of the spectrum in noisy cases. 1
ABSTRACT In this paper we calculate both call and burst blocking probabilities of ON–OFF traffic ... more ABSTRACT In this paper we calculate both call and burst blocking probabilities of ON–OFF traffic sources with retrials. Calls of service-classes arrive to a single link according to a Poisson process and compete for the available link bandwidth under the complete sharing policy. Blocked calls may immediately retry one or more times to enter the system, with reduced bandwidth and increased mean service time requirements. Call blocking occurs when a call cannot enter the system with its last bandwidth requirement, due to lack of bandwidth. Accepted calls enter the system via state ON and may alternate between states ON and OFF, or remain always in state ON. When a call is transferred to state OFF it releases the bandwidth held in state ON, so that this bandwidth becomes available to new arriving calls. When a call tries to return to state ON, it re-requests its bandwidth. If it is available a new ON-period (burst) begins. Otherwise burst blocking occurs and the call remains in state OFF. The proposed ON–OFF retry models do not have a product form solution and therefore the calculation of call and burst blocking probability is based on approximate formulas. The formulas we propose for the call blocking probabilities are recursive, whereas for the burst blocking probabilities are robust. Simulation results validate our analytical methodology. For further evaluation, the results of the ON–OFF retry models are compared with those of the ON–OFF model without retrials. We also discuss the extension of the proposed formulas in the case of a fixed-routing network.
We consider the fair bandwidth allocation problem of ABR calls by a Connection Admission Controll... more We consider the fair bandwidth allocation problem of ABR calls by a Connection Admission Controller (CAC) at call setup. Its general solution is given by applying the "max-min fairness allocation policy". Extensions of this policy take into account the Minimum Cell Rate (MCR) and the Peak Cell Rate (PCR) traffic description parameters, which are essential for ABR. These extensions are distinguished according to the existence or non-existence of weights in the policy. The weights may be defined independent of MCR or dependent on MCR. In this paper firstly we present a linear programming model, which describes in a parametric way both weighted and unweighted bandwidth allocation policies for ABR services. Because of the parametric nature of the LP model, it can be easily extended in order to take into account various bandwidth allocation policies. Secondly, we propose an unweighted fair bandwidth allocation policy in which ABR calls are grouped in categories, according to th...
ABSTRACT The present paper reports on a novel technique that links the basic concepts of multi-ba... more ABSTRACT The present paper reports on a novel technique that links the basic concepts of multi-band based Automatic Speech Recognition (ASR) and Missing Feature Theory (MFT). In the multi-band paradigm the frequency spectrum is partitioned in narrow bands and processed independently. In the context of MFT, the stochastic framework of continuous density Hidden Markov Models (HMMs) is adapted to handle time frequency regions corrupted by noise.
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Papers by George Kokkinakis