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Mobile ad-hoc networks are one of the most active research areas in the wireless communications field. These networks do not need any fixed infrastructure or configuration, easily adapting to difficult scenarios and types of use. Since mobile nodes are often powered by limited batteries, energy is an important issue in MANETs since the lack of a node can lead to the partitioning of the network. Recently,...
Location estimation and tracking for the mobile stations have attracted a significant amount of attention in recent years. Moreover, different types of signal sources are considered available to provide the measurement inputs for location estimation and tracking. In this paper, a hybrid unified Kalman tracking (HUKT) technique is proposed to provide an integrated algorithm for precise location tracking...
In this paper a new speed estimation method for pedestrian dead-reckoning is presented. The proposed approach is based on the estimated channel frequency response of Digital Video Broadcasting-Terrestrial (DVB-T) signals. Correlation coefficients are calculated from the acquired envelopes and the coherence time is estimated for a certain correlation level. The algorithm gives an average error of less...
In order to overcome the indoor coverage problem for residential users, the deployment of home base stations (also referred as home-eNB) has been regarded as a promising solution. However, the unpredictable deployment pattern of home-eNBs makes centralized network planning impractical and requires distributed spectrum planning to achieve effective interference management. In this paper, by enabling...
This paper addresses the effect of timing synchronization errors for two different multicarrier techniques CPOFDM and FBMC. Such errors degrade the performance of the reference receiver by causing multi user interference. This interference occurs when the signals from different transmitters arrive at a given receiver with arbitrary timing misalignments, leading to the destruction of orthogonality...
This paper tackles the problem of fast varying channel estimation in LTE systems. Particular attention is given to downlink transmission where OFDMA is used as the multiple access technique for the air interface. In OFDMA, fast variation of the channel results in significant inter-carrier interference (ICI) which cannot be mitigated with conventional estimation and equalization techniques. In this...
Previous work predominantly assumes that the pdf of range measurements exhibit Gaussian characteristics. The objective of this paper is to scrutinize this assumption for different environments. Experiments are performed in both outdoor and indoor environments with Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) conditions using IEEE 802.15.4 compliant devices. These devices consist of a low-cost...
The IEEE 802.11 standard conformant wireless communication stations have multi-rate transmission capability. To achieve greater communication efficiency, multi-rate capable stations use rate-adaptation to select appropriate transmission rate according to variations in the channel quality. This paper proposes a novel rate-adaptation scheme where the decision of rate selection relies on the mutual feedback...
The estimation of the position of an emitting source is an important aspect of emerging cognitive radio systems. We readdress the known problem of estimating the Direction-of-Arrival (DOA) of an emitting source via passive radio means, namely an antenna array. The challenges in the considered scenarios are (a) time-varying, terrestrial multipath propagation with medium-to-low SNR and (b) very short...
Wireless Sensor Networks (WSNs) have been of high interest during the past couple of years. One of the most important aspects of WSN research is location estimation. As a good solution of fine grained localization Reichenbach et al. introduced the Distributed Least Squares (DLS) algorithm, which splits the costly localization process in a complex precalculation and a simple postcalculation which is...
Is the temporal dimension alone sufficient to characterize contacts in opportunistic networks? Several studies analyze the temporal aspect of contacts with significant results concerning contact and inter-contact distributions. Nevertheless, only the temporal dimension does not give a complete overview of contact characterization. In this paper, we propose the surround indicator as a metric to exhibit...
In this paper, we investigate the performance of a cooperative relay network performing location estimation through time of arrival (TOA). We derive Cramer-Rao lower bound (CRLB) for the location estimates using the relay network. The analysis is extended to obtain average CRLB considering the signal fluctuations in both relay and direct links. The effects of the channel fading of both relay and direct...
This paper presents a new blind symbol timing offset (STO) estimation scheme for wireless orthogonal frequency division multiplexing (OFDM) systems with constant modulus constellation. In the proposed scheme, the STO estimation is performed by minimizing the power difference between either adjacent or consecutive subcarriers, which basically depends on the assumptions made on the channel conditions...
In this paper, we study the problem of random field estimation with wireless sensor networks. We adopt a Quantize-and-Estimate encoding scheme and focus our attention on two scenarios of interest: delay-constrained networks, in which the observations collected in a particular timeslot must be immediately encoded and conveyed to the Fusion Center (FC); and delay-tolerant (DT) networks, where the time...
In recent years, a lot of work has been done in the field of Opinion Detection in blogs but most of the research is based on machine learning or lexical based approaches. The objective of this paper is to focus on Social Network based evidences that can be exploited for the task of Opinion Detection. We propose a framework that makes use of the major elements of the blogosphere for extracting opinions...
Gesture input interfaces for mobile devices with a touch screen have become widespread. Although gesture interfaces in common use are limited to the small screens of these mobile devices, pointing interfaces for large screens using handheld devices or attachments are common. However, these devices increase the user's cognitive load because they are unable to cancel the effect of spatial cognition...
A Multilayer Perceptron (MLP) neural network based approach for estimation of the voltage stability L-index in a power system with Plug-in Electric Vehicles (PEVs) is presented. This technique overcomes the limitations of direct calculation of L-index from measurements at a load bus. The L-index calculation is dependent upon the no-load voltage phasor for any given system topology and operating condition...
The vertex-betweenness centrality index is an essential measurement for analyzing social networks, but the computation time is excessive. At present, the fastest algorithm, proposed by Brandes in 2001, requires O(|V| |E|) time, which is computationally intractable for real-world social networks that usually contain millions of nodes and edges. In this paper, we propose a fast and accurate algorithm...
The paper discusses performance evaluation of damping estimation methods and specifically evaluates the performance of a wavelet-based damping estimation method. The focus is on the damping estimation under the ambient conditions of the power system. Damping estimation results are reviewed in case of the simulated data because then real damping is known and can be compared with the estimated damping...
The purpose of this paper is to provide a framework for disruption risks in supply chain. The stages of the disruption risks management process consist of four components including disruption risks identification, assessment, implementation and monitoring. We investigate mitigation strategies for dealing with disruption risks. The paper provides directions for future research in supply chain risk...
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