Communication Noise Research Articles

Distributed Network Localization: Accurate Estimation With Noisy Measurement and Communication Information

This paper studies the relative position based node-localization problem for a sensor network without all nodes sharing a common reference frame in the presence of both measurement and communication noises. To solve the problem, a robust distributed orientation estimate algorithm and a robust distributed node-localization algorithm are designed, where unbiased estimators are constructed based on the historical measurement information to inhibit the measurement noise and the stochastic approximation method is adopted to inhibit the communication noise. Under the zero-mean and independence assumption on the measurement/communication noise, we show that all sensor nodes can asymptotically determine their own orientation angles and positions almost surely under the designed algorithms, if and only if the network contains at least one anchor node, and its communication and distance-sensing topology is 1-rooted at the anchor node set and the corresponding bearing sensing topology is connected. Moreover, the convergence rate is quantified if only the measurement noise or communication noise is involved. Simulation experiments are conducted to validate the effectiveness of the proposed algorithms.

A Combined Ray Tracing Method for Improving the Precision of the USBL Positioning System in Smart Ocean.

The ultra-short baseline positioning system (USBL) has the advantages of flexible application and easy installation, and it plays an extremely important role in the underwater positioning and communication. The error of the USBL in underwater positioning is mainly caused by a ranging error due to ray tracing, a phase difference error of the USBL, and acoustic noise in the underwater communication. Most of these errors are related to the changes in the sound speed during its propagation through the ocean. Therefore, when using the USBL for underwater detection, it is necessary to correct the sound speed profile in the detection area and optimize the ray tracing. Taking into account the actual conditions, this paper aims at correcting the model of underwater sound speed propagation and improving the tracking method of sound lines when the marine environment in the shallow sea area changes. This paper proposes a combined ray tracing method that can adaptively determine whether to use the constant sound speed ray tracing method or the equal gradient ray tracing method. The theoretical analysis and simulation results show that the proposed method can effectively reduce the error of slant distance in USBL compared with the traditional acoustic tracking method and the constant sound speed ray tracing method. The proposed sound ray correction algorithm solves the contradiction between the number of iterations and the reduction of positioning error and has engineering application value.

The feasibility of a multipurpose acoustic network in Baffin Bay

Operating autonomous underwater vehicles at high latitudes is a challenge because ice cover prevents the use of GPS or data communications. As a result, our scientific observations are biased towards late spring, summer, and early autumn when ships can navigate and autonomous platforms can safely surface. To address this problem, we studied the feasibility of a basin-scale multipurpose acoustic network called the “Baffin Bay Acoustic Navigation and Communication System” (BBANC). BBANC would deploy broadband low frequency sources and receivers, offering one-way communication, acoustic positioning, and acoustic thermometry services. Passive acoustic listening elements would support the study of marine mammal communication and ambient noise from ships, ocean-based resource exploitation, and ice dynamics, as well as gate acoustic source operation in the presence of marine mammals. We describe the challenges and design parameters for such a system, as well as define additional acoustic and remote sensing measurements required to complete a system design. Drawing from a large database of Baffin Bay hydrography, we present simulations of under-ice sound speed conditions, ice properties derived from satellite remote sensing and upward looking sonar data, and modelled acoustic propagation paths in an ice-covered Baffin Bay. We also assess the feasibility of non-coherent and coherent communication.

High levels of abiotic noise in volatile organic compounds released by a desert perennial: implications for the evolution and ecology of airborne chemical communication.

Plants release airborne volatile organic compounds (VOCs) in response to abiotic and biotic stimuli, including herbivory. These chemicals are used by insect parasitoids as sources of information that aid in finding hosts. It is unclear how biotic and abiotic factors interact to affect blend composition and the ability of insects to interpret signals. Here, we present a novel stimulus-space model, and use it to examine patterns of VOC emission. In field experiments, we manipulated herbivory levels and collected VOCs in a population of wild Datura wrightii, while simultaneously measuring key abiotic factors. We mirrored field experiments under controlled conditions in the lab, and used both sets of data to test predictions made by our proposed model. VOC blends were structured mainly by variation in abiotic factors, not herbivory. However, linear discriminant analysis showed that it is possible to distinguish different herbivory levels. We show that most compounds produced by D. wrightii are invariant, or respond solely to environmental variation or herbivory. Our results suggest that blend composition may be under selection for noise reduction, to maximize responses from potential receivers, and that abiotic variation can act as potentially strong sources of noise in chemical communication displays.

Robustness to noise of distributed averaging integral controllers in power networks

We investigate the robustness of distributed averaging integral controllers for optimal frequency regulation of power networks to noise in measurements, communication and actuation. Specifically, using Lyapunov techniques, we show a property related to input-to-state stability of the closed loop system with respect to this noise. Using this result, a tuning trade-off between controller performance and noise rejection is highlighted.

Mean-square composite-rotating consensus of second-order systems with communication noises**Project supported by the National Natural Science Foundation of China (Grant Nos. 61304155 and 11371049) and Beijing Municipal Government Foundation for Talents, China (Grant No. 2012D005003000005).

We study the mean-square composite-rotating consensus problem of second-order multi-agent systems with communication noises, where all agents rotate around a common center and the center of rotation spins around a fixed point simultaneously. Firstly, a time-varying consensus gain is introduced to attenuate to the effect of communication noises. Secondly, sufficient conditions are obtained for achieving the mean-square composite-rotating consensus. Finally, simulations are provided to demonstrate the effectiveness of the proposed algorithm.

Limits on reliable information flows through stochastic populations.

Biological systems can share and collectively process information to yield emergent effects, despite inherent noise in communication. While man-made systems often employ intricate structural solutions to overcome noise, the structure of many biological systems is more amorphous. It is not well understood how communication noise may affect the computational repertoire of such groups. To approach this question we consider the basic collective task of rumor spreading, in which information from few knowledgeable sources must reliably flow into the rest of the population. We study the effect of communication noise on the ability of groups that lack stable structures to efficiently solve this task. We present an impossibility result which strongly restricts reliable rumor spreading in such groups. Namely, we prove that, in the presence of even moderate levels of noise that affect all facets of the communication, no scheme can significantly outperform the trivial one in which agents have to wait until directly interacting with the sources—a process which requires linear time in the population size. Our results imply that in order to achieve efficient rumor spread a system must exhibit either some degree of structural stability or, alternatively, some facet of the communication which is immune to noise. We then corroborate this claim by providing new analyses of experimental data regarding recruitment in Cataglyphis niger desert ants. Finally, in light of our theoretical results, we discuss strategies to overcome noise in other biological systems.

Multi-UAVs Communication-Aware Cooperative Target Tracking

A kind of communication-aware cooperative target tracking algorithm is proposed, which is based on information consensus under multi-Unmanned Aerial Vehicles (UAVs) communication noise. Each UAV uses the extended Kalman filter to predict target movement and get an estimation of target state. The communication between UAVs is modeled as a signal to noise ratio model. During the information fusion process, communication noise is treated as a kind of observation noise, which makes UAVs reach a compromise between observation and communication. The classical consensus algorithm is used to deal with observed information, and consistency prediction of each UAV’s target state is obtained. Each UAV calculates its control inputs using receding horizon optimization method based on consistency results. The simulation results show that introducing communication noise can make UAVs more focused on maintaining good communication with other UAVs in the process of target tracking, and improve the accuracy of cooperative target tracking.

Second-order consensus of multi-agent systems with noises via intermittent control

ABSTRACTSecond-order consensus of multi-agent systems with noises via intermittent control is investigated in this paper. First, we study the mean-square consensus problem with communication noises by intermittent control. In order to reach consensus, under the strong directed interacted topology, by using the tools of graph theory and Lyapunov method, a distributed control protocol is proposed based on the noises and periodical intermittent information. The upper bound of noise strength in the sense of matrix norm and the lower bound of communication time duration are obtained. Second, a class of coupled system models which include delay-terms in their nonlinearities in the noisy environment is discussed. Under the balanced strongly connected topology, the sufficient conditions to achieve the mean-square average-consensus are obtained. Finally, simulations are given to illustrate the effectiveness of our results.

Coordinated consensus for smart grid economic environmental power dispatch with dynamic communication network

Combined economic environmental dispatch problem (CEEDP) is one of the greatest challenges of the future smart grids. It aims at reducing the total cost during the power production process considering the growing environmental impact due to the emission of gaseous pollutants of fossil fuels. This study develops a robust distributed algorithm based on consensus protocols in multi-agent systems, to solve the smart grid CEEDP with a practical communication network consisting of a dynamic communication network, randomly communication failure, transmission delay and noise in communication channels. The proposed algorithm is fully distributed and cooperative in such a way that it eliminates the need for a central energy-management unit, or a leader. The performance of the fully decentralised consensus protocol was evaluated on the IEEE 30-bus and the IEEE 118-bus test system. A comparison with previous consensus algorithms proves the supremacy of the proposed approach in terms of its robustness under dynamic communication network with randomly link failure.

A 51.6 Mb/s Experimental VLC System Using a Monochromic Organic LED

An organic light emitting diode (OLED) shows characteristics different from a traditional semiconductor LED when both are applied to visible light communication (VLC). This paper first experimentally characterizes its static and dynamic communication properties with varying input signals. This band-limited and power-limited light source leads to unique communication channel and noise models. Accordingly, the orthogonal frequency-division multiplexing in conjunction with offset quadrature amplitude modulation (OFDM-OQAM) is applied, and its performance is compared against the traditional dc-biased optical OFDM. To further enhance the communication performance, a bit and power loading algorithm and a proper equalization algorithm are jointly implemented to combat the channel frequency selectivity and increase the data rate. A bit-rate of 51.6 Mb/s based on a monochromic OLED is experimentally achieved through the proposed design. The rate is comparable to the multicolor OLEDs-based VLC link in the literature.

Robust Distributed Estimation for Linear Systems Under Intermittent Information

We provide a comprehensive solution to the estimation problem of the state for a linear time-invariant system in a distributed fashion over networks that allow only intermittent information transmission. By attaching to each node an observer that employs information received from its neighbors triggered by asynchronous communication events, we propose a distributed state observer that guarantees global exponential stability of the zero estimation error set. The design of parameters is formulated as linear matrix inequalities. A thorough robustness analysis of the proposed observer to unmodeled dynamics, unknown communication times, as well as measurement and communication noise characterized in terms of input-to-state stability is presented. These properties of the proposed observer are shown analytically and validated numerically.

Mean-square consensus of heterogeneous multi-agent systems with communication noises

This paper addresses the mean-square consensus problems of continuous-time heterogeneous multi-agent systems with communication noises. First, in order to attenuate the communication noises, time-varying consensus gains are applied in the consensus algorithm. Then, by using the tools of algebraic graph theory and stochastic analysis, sufficient conditions for the mean-square consensus are given for the cases with and without a leader. Finally, simulations are provided to demonstrate the effectiveness of the proposed algorithms.

Leader-Follower Formation Control of UUVs with Model Uncertainties, Current Disturbances, and Unstable Communication.

Unmanned underwater vehicles (UUVs) have rapidly developed as mobile sensor networks recently in the investigation, survey, and exploration of the underwater environment. The goal of this paper is to develop a practical and efficient formation control method to improve work efficiency of multi-UUV sensor networks. Distributed leader-follower formation controllers are designed based on a state feedback and consensus algorithm. Considering that each vehicle is subject to model uncertainties and current disturbances, a second-order integral UUV model with a nonlinear function is established using the state feedback linearized method under current disturbances. For unstable communication among UUVs, communication failure and acoustic link noise interference are considered. Two-layer random switching communication topologies are proposed to solve the problem of communication failure. For acoustic link noise interference, accurate representation of valid communication information and noise stripping when designing controllers is necessary. Effective communication topology weights are designed to represent the validity of communication information interfered by noise. Utilizing state feedback and noise stripping, sufficient conditions for design formation controllers are proposed to ensure UUV formation achieves consensus under model uncertainties, current disturbances, and unstable communication. The stability of formation controllers is proven by the Lyapunov-Razumikhin theorem, and the validity is verified by simulation results.

Quality aspects of music used as a background noise in speech communication over mobile network

This paper compares the effect of send-side music and environmental noise as background noise in a telephone communication. The study focuses on the quality experienced by the end user in the context of NB, WB and SWB mobile speech communication. The subjective test procedure defined in ITU-T Rec. P.835 is followed in this study. The results show that music as background noise in telephone conversation deteriorates the overall quality experienced by the end user. Moreover, the impact of music background noise on the quality is similar to that of the environmental noise. Furthermore it is shown that the music background noise seems to be slightly less intrusive than the environmental noise, especially when it comes to the lower SNR.

Robustness of an innate releasing mechanism against degradation of acoustic communication signals in the grasshopper Chorthippus biguttulus.

Noise is a challenge for animals that use acoustic communication to find a mate. A potent source of noise in animal communication is that arising from other conspecific signals, whose co-occurrence can result in extensive interference-evident as the so called "cocktail-party problem"-that may affect the receiver mechanisms to detect potential mates. We studied grasshopper females to explore how modifications of the song pattern influence song recognition. First, we degraded an attractive model song with random fluctuations of increasing amplitudes out of different frequency bands, and determined "critical degradation levels" at which the females ceased to respond. A masker band with frequencies between 0 and 200Hz, which covers the frequency range of the natural song envelope, was by 3-5dB more destructive in hampering signal recognition than frequencies above 200Hz. As second approach, we applied temporal disturbances such as accentuations or gaps at different positions within the song subunits and observed how response behavior was affected. Accentuations at subunit start increased, whereas those in the midst or at the end of a subunit reduced attractiveness. Gaps at these positions had diverse effects. The results are discussed with respect to neuronal filtering.

Asymptotic Properties of Primal-Dual Algorithm for Distributed Stochastic Optimization over Random Networks with Imperfect Communications

This paper studies a distributed stochastic optimization problem over random networks with imperfect communications subject to a global constraint, which is the intersection of local constraint sets assigned to agents. The global cost function is the sum of local expectation-valued convex cost functions. By incorporating the augmented Lagrangian technique with the projection method, a stochastic approximation--based distributed primal-dual algorithm is proposed to solve the problem. Each agent updates its estimate by using the local noisy observations of its gradient function and the imperfect information derived from its neighbors. For the constrained problem, the estimates are first shown to be bounded almost surely (a.s.) and then are proved to converge to the optimal solution set a.s. Furthermore, the asymptotic normality and efficiency of the algorithm are addressed for the unconstrained case. The results demonstrate the influence of random networks, communication noises, and gradient errors on the performance of the algorithm. Finally, numerical simulations are presented to demonstrate the theoretic results.

Phase transitions in distributed control systems with multiplicative noise

Contemporary technological challenges often involve many degrees of freedom in a distributed or networked setting. Three aspects are notable: the variables are usually associated with the nodes of a graph with limited communication resources, hindering centralized control; the communication is subject to noise; and the number of variables can be very large. These three aspects make tools and techniques from statistical physics particularly suitable for the performance analysis of such networked systems in the limit of many variables (analogous to the thermodynamic limit in statistical physics). Perhaps not surprisingly, phase-transition like phenomena appear in these systems, where a sharp change in performance can be observed with a smooth parameter variation, with the change becoming discontinuous or singular in the limit of infinite system size.In this paper, we analyze the so called network consensus problem, prototypical of the above considerations, that has previously been analyzed mostly in the context of additive noise. We show that qualitatively new phase-transition like phenomena appear for this problem in the presence of multiplicative noise. Depending on dimensions, and on the presence or absence of a conservation law, the system performance shows a discontinuous change at a threshold value of the multiplicative noise strength. In the absence of the conservation law, and for graph spectral dimension less than two, the multiplicative noise threshold (the stability margin of the control problem) is zero. This is reminiscent of the absence of robust controllers for certain classes of centralized control problems. Although our study involves a ‘toy’ model, we believe that the qualitative features are generic, with implications for the robust stability of distributed control systems, as well as the effect of roundoff errors and communication noise on distributed algorithms.

De–Black Boxing Media

Reading Avital Ronell’s unconventionally designed The Telephone Book implies reading material form as well as semantic content. Such a reading emphasizes the book’s typographical illegibilities, which become the figure for the space between person and thing. These illegibilities manifest as unreadable noise, interventions on the print page that produce a technological feminine. Situated alongside ANT (actor-network theory), media theory, and cyborg feminism, the technological feminine gestures at the limits of these attempts to de–black box media, insisting on an irreducible noise or static in communication.

Instrumento de avaliação das barreiras para implementação da gestão por competência na instituição pública de ensino

Competence management has been identified as an alternative managerial model to the instruments traditionally used by organizations. Based on the assumption that the mastery of certain resources is determinant in the superior performance of individuals and organizations, this model is fundamentally designed to manage the gap or gap in skills, that is, to reduce as much as possible the discrepancy between skills organizational goals and those already available in the organization. The objective of this study was to develop an instrument for the evaluation of institutional barriers to the implementation of competency management in a public educational institution. A quantitative research was carried out, with a descriptive approach combined with a case study. A total of 132 administrative technical servers and 18 managers of the three campuses that integrated the Pedro II College/ RJ were interviewed, who answered a semi-structured questionnaire. The research carried out in the literature showed that the main barriers to the implementation of Management by Competence in Public Administration were: server evaluation, training/training, noise in internal communication, great information demand, public selection, lack of servers, change of management and legislation. Thus, the results observed in this study are in line with the main obstacles, listed in the literature, for the implementation of Management by Competence in the Pedro II College.