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Low-complexity error concealment techniques for missing macroblock (MB) recovery based on the boundary matching principle are extensively studied and evaluated. In this paper, an improved boundary matching algorithm (BMA) using adaptive search is presented to conceal channel errors in inter-frames of video images. The proposed scheme adaptively selects proper candidate regions to conceal the artifact...
A simple low-profile antenna with an enhanced gain is proposed for multiband orthogonal frequency-division multiplex (MB-OFDM) ultra wide band (UWB) systems. Using proximity coupling along the surface we demonstrate a technique to enhance the gain at lower UWB frequencies. The antenna is realized as a conventional CPW-fed printed disc monopole with unconventional metallic patches on the top of the...
We propose a method for estimating the fundamental frequency and localizing a pulsatic, quasiperiodic signal in a correlated mixture. The spectra of the correlated signal is obtained by using the short-time Fourier transform (STFT). For a quasiperiodic, pulsatic signal, the frequency signal variation over the frame index is itself quasiperiodic and pulsatic. In a mixture, the overlap of the spectra...
Noise interference and data loss are two major problems that affect the processing results of image data transmission and storage. Restoration of the lost information of an image based on the existing information is the essence of inpainting. In this paper a new algorithm based on Sample and Hold interpolation and Iteration is proposed for reconstructing damaged images from existing regions and is...
In speech processing the short-time magnitude spectrum is believed to contain most of the information about speech intelligibility and it is normally computed using the short-time Fourier transform over 20-40 ms window duration. In this paper, we investigate the effect of the analysis window duration on speech intelligibility in a systematic way. For this purpose, both subjective and objective experiments...
This article presents a thorough statistical analysis of the capacity of orthogonal space-time block coded (OSTBC) Nakagami-lognormal (NLN) multiple-input multipleoutput (MIMO) channels. The NLN channel model allows to study the joint effects of fast fading and shadowing on the statistical properties of the channel capacity. We have derived exact analytical expressions for the probability density...
Many navigation problems involve constraints. For example, motor vehicle travel tends to be constrained by road and building boundaries. We consider filtering problems where censuring functions can be used to constrain the measurements. It is established that the ensuing filtered estimates are unbiased, provided that the underlying probability density functions are even and the censuring functions...
A system comprising of a digital infrared sensitive camera and high intensity infrared illuminator was used to track infrared reflective tape on a coaxial biopsy needle. Data was sent in real-time to a computer where needle position with respect to the desired path was displayed in 2D, enabling instant corrections in needle trajectory by the operator. In this preliminary study, two operators each...
A new approach for embedding the authentication data using fractal and chaos technique is developed in this paper. This approach is to meet the need for authentication, including fragility and inalterability. Using chaos technique and the keyword extracted from the image itself, it is so unlikely to predict the blocks used for embedding the data. The first section is dedicated to introduce digital...
The Mel-Frequency Cepstral Coefficients (MFCC) feature extraction method is a leading approach for speech feature extraction and current research aims to identify performance enhancements. One of the recent MFCC implementations is the Delta-Delta MFCC, which improves speaker verification. In this paper, a new MFCC feature extraction method based on distributed Discrete Cosine Transform (DCT-II) is...
In a cognitive radio network (CRN), secondary (or unlicensed) users intend to share unoccupied frequency spectra of primary (or licensed) users in order to improve the efficiency of spectrum usage. In this paper, we address the problem of dynamic spectrum sharing in a CRN consisting of multiple SUs that compete non-cooperatively and independently with each other to demand spectrum access to a single...
Selection combining cascaded with maximum-ratio combining (SC/MRC), which is particularly useful when site diversity is available, combined with low-density parity-check (LDPC) codes is able to combat the effects of fading. The bit-error rate (BER) expressions of uncoded SC/MRC and SC/MRC with LDPC codes over an independent and identically distributed Rayleigh-fading channel are derived based on the...
Traditional scheduling algorithms are focused in maximizing system throughput considering a grade of fairness. However, maximizing the system throughput does not necessarily result in maximizing the number of satisfied users (users with a packet delay below a threshold). More over, the throughput maximization could cause a low grade of fairness. In this paper, we propose a low complexity scheduling...
This paper examines the geolocation of standard compliant WiMAX subscriber stations based on timing adjust values captured from the air interface during network entry and initial ranging. Field tests were conducted to verify a linear correlation between timing adjust and distance. Repeated observations at fixed distances established the variance within timing adjusts. Results of this field testing...
This paper presents propagation characteristics of the wideband MIMO channel based on indoor measurements. An accurate characterization of the K-factor is very important in design issues in indoor environments, especially for MIMO and broadband networks. We have performed measurement campaigns for the indoor wideband channel using the Band Exploration and Channel Sounding (BECS) system developed by...
This paper investigates the use of an Acoustic Vector Sensor (AVS) for tracking a moving speaker in real time through estimation of the Direction of Arrival (DOA). This estimation is obtained using the MUltiple SIgnal Classification (MUSIC) algorithm applied on a time-frame basis. The performance of the AVS is compared with a SoundField Microphone which has similar polar responses to the AVS using...
Detection oriented UWB wireless sensor node places several stringent requirements on compatibility, power consumption and implementation cost. The compatibility requirements mandate the digital realization by using high speed analog-to-digital converter (ADC). However, the need of full resolution, extremely high speed ADC contradict to the application demand of low cost and power consumption. Finite-resolution...
This paper presents a novel technique of allocating optimized power to wireless sensor nodes in a nonlinear measurement model. We consider the problem of distributed estimation of a random vector-valued parameter in an energy-constrained sensor network. Noise-corrupted local nonlinear observations are transmitted by spatially distributed sensor nodes towards fusion center where estimation of the vector...
The ultra-wideband (UWB) technology is recognized as an ideal candidate to provide accurate localization in challenging indoor environments where other technologies, e.g. WiFi or ZigBee cannot yield good accuracy due to their signal bandwidth limitation. The energy detection receiver is currently one of the most promising low complexity non-coherent architectures that neither requires high sampling...
Irregular LDPC codes have shown to give performances closer to capacity than their regular counterparts. The intuitive reasoning backed by experimental evidence given by its founder (Luby et al.) was the presence of a wave-effect. It was shown that only with the presence of a carefully optimized irregularity degree profile, comes the better performance. Conventionally this irregularity profile is...
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