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WiFi has emerged as a pivotal technology for mobile devices offering the potential for exceptional connectivity speeds. Unfortunately, the performance of WiFi may vary significantly making WiFi link characterization (and more broadly the path characterization) an essential element of the user Quality of Experience (QoE). The key challenge that emerges with respect to link characterization is how to...
The management of radio congestion in the control channel is one of the active research areas in Vehicular Ad-hoc Networks (VANETs). Many congestion control protocols have already been proposed to ensure an optimal management of the radio control channel. LIMERIC is a well-known congestion control protocol which was adopted by the current ETSI standardization process to be applied in the future deployment...
HTTP Adaptive Streaming (HAS) is a widely used video streaming technology that suffers from a degradation of user's Quality of Experience (QoE) and network's Quality of Service (QoS) when many HAS players are sharing the same bottleneck link and competing for bandwidth. The two major factors of this degradation are: the large OFF period of HAS, which causes false bandwidth estimations, and the TCP...
Forwarding fault detection increases the robustness of network connectivity by finding and allowing to react to faulty routers. One of the essential steps in forwarding fault detection is summarizing the observed traffic at different vantage points, so that the behavior of each monitored router can be assessed using a traffic validation function. This paper studies and characterizes 3 sketches (AGMS,...
Ocean remote sensing based satellite image is useful for the Earth observation such as altimetry, Significant Wave Height, and wind speed measurement. However, The Global Navigation Satellite System (GNSS) represents the new challenge using special feature of the reflected signal to observe characteristics of the ocean call GNSS - reflectometry. The advantages of this technique are that using the...
When dealing with Quality of Experience (QoE) and in particular perceptual quality assessment and modeling, averaging is a common occurrence. For instance, the most commonly used measure of QoE is the aptly-called Mean Opinion Score (MOS), which is intended to represent an idealized average subject's rating of the quality. Another form of averaging occurs when choosing and preparing the samples used...
A particular problem in satellite communications is the estimation of the current operating point of a bent-pipe transponder. Various special effects aggravate this estimation problem, among which the capture effect, gain compression, unknown attenuation in the transmission channel, or noisy received signals are the most prominent. In most practical cases, operators desire a fully blind estimator...
Regression-Discontinuity Design is a non-experimental method to estimate the impacts of social welfare programs in situations where the treatment assignment is determined by whether an observed variable (running variable) is above or below a known cutoff point. The main idea behind RDD is that individuals whose running variable is just above or just below the cutoff are similar, and so, any differences...
Modern Graphics Processing Units (GPUs) provide much higher off-chip memory bandwidth than CPUs, but many GPU applications are still limited by memory bandwidth. Unfortunately, off-chip memory bandwidth is growing slower than the number of cores and has become a performance bottleneck. Thus, optimizations of effective memory bandwidth play a significant role for scaling the performance of GPUs. Memory...
In this work, two access point (AP) selection mechanisms called STOOP and MD-STOOP are presented for enterprise wireless local area networks (WLANs). STOOP utilizes first- order stochastic dominance (FSD) tools to develop a runtime algorithm that probes the network to compare the quality of service from multiple APs in a stochastic manner. MD-STOOP utilizes the concept of mean dominance (MD) to select...
We propose an elaboration and visualization approach for spectral measurement that allows to monitor the progress of the estimation process in real time while maintaining a quaqi-constant resolution bandwidth over frequency ratio in a wide frequency range. The approach we propose is particularly useful in the estimation of low frequency noise, where the flicker component is dominant, since it allows...
We propose a simple but effective approach for the estimation of power spectra at very low frequencies (down to the tens of mHz range) by exploiting the characteristics of the sound system (sound card) and the computational power of modern personal computers. A simple mixer board has been designed that allows to transfer the low frequency region of the spectrum at a higher frequency in the passband...
Clustering is one of the most important unsupervised classification strategies in data analysis. In this sense, a new clustering approach proposed a fast search algorithm of cluster centers based on their local densities has taken place. In the present paper, we suggest a new performed approach that combine the estimation of the local density and the use of the entropy. So the clustering algorithm...
Many real world networks are characterized by long delays, frequent path breaks, mobility, and lack of infrastructure. Class of networks which can cope up with such environments are called Delay Tolerant Networks (DTN). Architectures with a separate bundle layer, have been implemented in specific applications such as interplanetary networks (IPNs). However, the addition of bundle layer to existing...
A cognitive radar adapts the transmit waveform in response to changes in the radar and target environment. In this work, we analyze the recently proposed sub-Nyquist cognitive radar wherein the total transmit power in a multi-band cognitive waveform remains the same as its full-band conventional counterpart. For such a system, we derive lower bounds on the mean-squared-error (MSE) of a single-target...
Information theoretic measures (e.g. the Kullback Liebler divergence and Shannon mutual information) have been used for exploring possibly nonlinear multivariate dependencies in high dimension. If these dependencies are assumed to follow a Markov factor graph model, this exploration process is called structure discovery. For discrete-valued samples, estimates of the information divergence over the...
In many angle of arrival (AoA) estimation algorithms for broadband signals a-prior knowledge about the impinging signals' bandwidth is required for the algorithms to function. In this paper, we present a new technique for estimating the AoA and the bandwidth of the received broadband signals without requiring any knowledge of the bandwidth of the received signals. The proposed technique consists of...
Estimation of bias field together with the tissue class of a noisy Magnetic Resonance image has been a challenging task because of the nonlinear nature of bias field. In order to address this issue we have proposed two new schemes. The first one is the recursive framework, where class labels and bias fields have been estimated simultaneously. In one part of the recursion, a variable variance Adaptive...
This paper proposes a signal reforming algorithm based three-phase phase-locked loop (PLL) to estimate the phase angles of an unbalanced and harmonics affected three-phase voltage system. This technique transforms the unbalanced waveforms into a balanced one by first attenuating the harmonic components and then balancing the voltage waveforms so that any conventional synchronous reference frame (SRF)...
This paper proposes speed estimation method for the incremental position encoders. This method uses variable angular path to keep the bandwidth and accuracy in the specified range regardless of the current speed. This paper also describes existing speed estimation methods, their strong and weak points. Moreover, non-idealities of the incremental encoders are discussed and compensation algorithm is...
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