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In this paper we have proposed a technique for cooperative localization where localization is done in distributive fashion without using any additional broadcast by nodes. The method relies on a fixed scheduled ultra-wideband (UWB) pulse transmissions by nodes in a predetermined way. The advantages of the proposed method is simpler hardware, comparatively less pulse transmission in the system hence...
To accommodate the dynamic characteristics in opportunistic networks, ``carry-and-forward'' technique is utilized. In this paradigm, the next hop forwarding relay node is usually decided by inferring future contact opportunities. A practical method is to predict future encounter time using nodes' contact history. But limited by prediction accuracy, this method has only an uncertain effect on improving...
LED-ID (light emitting diode - identification) is considered as a strong candidate for the future lighting technology due to its lower consumption, lower voltage, longer lifetime, smaller size, and cooler operation. A key issue in LED-ID systems is the guarantee of seamless connectivity when an user, as known as reader, moves from coverage area of a tag to another tag's coverage area. Link switching...
The performance of a continuous-discrete Kalman filter using multi-sensor observations with irregular sampling patterns and/or delay in the measurement path is analyzed in terms of the associated error-covariance matrix. Such irregularities occur in geographically-distributed systems (such as the electric power grid) when observations are transmitted to an estimation/control center via an unreliable...
Inter-carrier interference (ICI) caused by high Doppler frequency shift has severe impact on link performance and capacity for High-Speed Railway (HSR) communications. In this paper we investigate the ICI mitigation scheme by utilizing the estimation and pre-compensation of high Doppler shifts in Long Term Evolution for Railway (LTE-R) systems with distributed remote radio units (RRU). We propose...
This work presents an analysis of digital predistortion (DPD) architectures for radio-frequency digital-to-analog convertor (RFDAC) based direct digital to RF transmitter (DRF). The nonlinearity of the DRF frontend is determined by circuit simulation. Direct learning and indirect learning structures using least mean square (LMS) and normalized LMS (NLMS) estimation algorithm are evaluated with respect...
For high-accuracy AC voltage measurements, sampling errors can contribute significantly to increase the incertitude. Fractional delay is a simple technique to reduce sampling errors, improving the accuracy of electrical digital measurements. In this paper we combine the fractional delay sampling technique with Principal Component Analysis, applying this technique to high-accuracy measurements.
In the article we propose a method of improving ITU-T E-model MOS estimate of VoIP call quality. The improvement consists of including the effects of network jitter as measured and distributed in RTCP packets; jitter buffer size at receiver and codec packetization settings as input parameters of E-Model. Our method uses Pareto/D/1/k system for modeling general VoIP input traffic stream interarrival...
This paper is concerned with the optimal filter problems for networked systems with random transmission delays, while the delay process is modeled as a multi-state Markov chain which incorporates the data losses naturally. By defining an indicator function of the random delay, the optimal filter problems are transformed into the ones of the standard Markov jumping parameter measurement system. We...
In this paper, we will consider the problems where observation delay is time-varying and design distributed estimators by combining a consensus strategy. The optimal local estimator for every node with time-varying observation delay is first designed, which plays an important role in the distributed estimator design. Then the optimal distributed estimator for any choice of the consensus gain is proposed...
If network congestion occurs, packets cannot be delivered timely, the data rate decreases significantly and the required level of QoS cannot be achieved for all nodes. Especially in Home Area Networks (HANs) with limited uplink bandwidth for internet access, congestion is a major problem. Different approaches for congestion aware link sharing and QoS provisioning exist. Also the Distributed Fair Congestion...
Wireless traffic that is destined for a certain device in a network, can be exploited in order to minimize the availability and delay trade-offs, and mitigate the Energy consumption. The Energy Conservation (EC) mechanism can be node-centric by considering the traversed nodal traffic in order to prolong the network lifetime. This work describes a quantitative traffic-based approach where a clustered...
Parallelization of big-data analytics services over a federation of heterogeneous clouds has been considered to improve performance. However, contrary to common intuition, there is an inherent tradeoff between the level of parallelism and the performance for big-data analytics principally because of a significant delay for big-data to get transferred over the network. The data transfer delay can be...
Although there have been a plethora of studies on TCP performance in supporting of various applications, relatively little is known about the interaction between TCP and BGP, which is a specific application running on top of TCP. This paper investigates BGP's slow route propagation by analyzing packet traces collected from a large ISP and Route Views Oregon collector. In particular we focus on the...
Classical localization systems based on TDOA/FDOA use a two-stage estimation approach. In the first stage, pairs of sensors share data to estimate TDOA/FDOA. Then, the extracted TDOA/FDOA measurements are used to estimate the emitter location. In some recently published methods, an optimal single-stage approach named Direct Position Determination (DPD) has been proposed to improve the position estimation...
State monitoring is widely used for detecting critical events and abnormalities of distributed systems. As the scale of such systems grows and the degree of workload consolidation increases in Cloud data centers, node failures and performance interferences, especially transient ones, become the norm rather than the exception. Hence, distributed state monitoring tasks are often exposed to impaired...
A Service-Based Application (SBA) is built by defining a workflow that composes and coordinates different Web services available via the Internet. In the context of on-demand SBA execution, suitable services are selected and integrated at runtime to meet different non-functional requirements (such as price and execution time). In such dynamic and distributed environment, an important issue is to guarantee...
TheMUSIC-group delay spectrum has been hitherto used for high resolution direction of arrival estimation using a limited number of sensors. In this work we discuss the significance of the MUSIC-group delay spectrum for robust direction of arrival estimation using shrinkage estimators. The MUSIC-group delay spectrum computed using shrinkage estimation of the covariance matrix, is found to be robust...
This paper proposes a LMMSE-based channel estimator which, unlike the classical LMMSE estimator, does not require the covariance matrix of the channel nor its estimation. Actually, we add at the receiver side a fully adjustable filter, which acts like an artificial channel and hides the physical channel. We then perform an LMMSE estimation of the sum of the physical and artificial channel using the...
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