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The overall structure of pertussis toxoid has been established by analysis of its tryptic digest using two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS), capillary liquid chromatography-matrix-assisted laser desorption ionization-tandem mass spectrometry (CapLC-MALDI-MS/MS), and ultraperformance liquid chromatography-mass spectrometry E (UPLC-MS E ). In addition...
Multilateration schemes presented in literature generally focus on deriving a minimum solution. The problem of how to make optimal use of the information about specific spatial configurations of the transmitter of interest and the associated set of observers in a wireless network is not generally considered. Such considerations are especially important when using Time Difference of Arrival methods...
Obtaining precise geolocation estimates for mobile devices requires knowledge of the local propagation velocity of light. Under common atmospheric conditions, incorrect propagation velocity estimates introduce systemic dilution of precision using time difference of arrival techniques. Modeling local propagation velocity as a function of common local meteorological variables yields corrected velocity...
In this paper, we present a novel energy consumption analysis of the flow-specific Cooperative Wireless Sensor Network Medium Access Control (CWS-MAC) protocol utilizing a nine-state radio energy model that includes both steady state and transient state energy consumption behavior. CWS-MAC is a traffic-adaptive, energy-efficient medium access scheme that has been shown in the literature to outperform...
This paper implements spectrum sensing using a radio frequency sensor network and analyzes the performance of this implementation through simulation. A sensor network based cooperative wideband spectrum sensing scheme is proposed for the implementation of this task. In the proposed scheme, wavelet-based multi-resolution spectrum sensing, which was originally proposed for cognitive radio applications,...
Space-based networks have long been proposed to support a myriad of both space-based and terrestrial-based applications. While much research has been done on the individual systems that will comprise this network, it was not until recently that the system was examined as a whole utilizing the tools of systems of systems engineering to provide integration and optimization. In this work, we continue...
The energy efficiency trade-offs available between centralized and distributed solutions in unattended wireless sensor network deployments such as those that support remote battlefield monitoring remain an open research question. In this paper, we compare the relative energy efficiency of these two approaches in multi-hop wireless sensor networks. We develop a framework that includes both total and...
Current wireless sensor network applications face challenging power constraints that demand low duty cycles. In this paper, we propose an energy-efficient, flow-specific medium access scheme that is capable of achieving low duty cycles while taking advantage of the performance improvements available through a flow-specific medium access approach. The scheme is based on an adaptive sleep and wake cycle...
A method for file transfer utilizing forward error correction (FEC) to pass traffic over deployed wireless sensor networks is studied. The entire wireless sensor network is modeled as an error-prone virtual physical link. Previous work in the area of terminal communication across the sensor network is expanded upon to include file transfer in order to provide a more capable channel and a basis for...
Sensor array beamforming performance using independently mobile antennas connected through a wireless sensor network is analyzed where a performance metric is proposed enabling mitigation of the perturbation of array factor formation caused by dynamic node positions. Wireless networking has expanded array design possibilities to include wirelessly connected elements; however, static positioning of...
A method is proposed to determine reset timing for phase weight recalculation required in coherent beamforming using wirelessly connected independently mobile nodes to form an array aperture. Without the tether of a wired connection, elements in an array may be independently mobile. However, coherent beam formation requires position data at time of intercept to maintain target focus. Implementing...
In this paper, we formally introduce the novel concept of traffic-adaptive, flow-specific medium access control and show that it outperforms contention, non-contention and hybrid medium access schemes. A traffic-adaptive, flow-specific mechanism is proposed that utilizes flow-specific queue size statistics to select between medium access modes. A general model for traffic-adaptive, flow-specific medium...
Several recent publications have sought to adopt a system-of-systems approach to view the ballistic missile defense system as a large-scale, wireless network. This approach implicitly relies on an effective medium access scheme that can accommodate the large propagation delays encountered in a satellite network. While existing satellite networks typically employ a form of time division multiple access,...
We present the design of a randomly distributed radio frequency signal detection and reception array constructed of wireless sensor network nodes. The design stresses initial signal detection using the wireless network array. All other array operations depend on first detecting a signal of interest prior to activating follow-on sequences of signal processing, potentially including geolocation of the...
Collaborative beamforming can be used in a wireless sensor network to increase the effective communication range of the network. In this paper, the power consumption of existing least squares based beamforming solutions is analyzed and an energy-efficient, distributed algorithm for beamformer weight calculation is proposed. Simulation results are provided to demonstrate that the proposed algorithm...
This paper proposes a source localization scheme using random arrays of wireless sensors that addresses multipath propagation. Taking advantage of the dominant reflections, the proposed solution finds the location of a signal source by triangulation using the direction of arrival estimations of both the line-of-sight and the reflected components. It uses a space division multiple access, spread spectrum-based...
Adopting a system-of-systems perspective, a wide area network comprised of ballistic missile defense satellites and terrestrial nodes can be viewed as a hybrid, large-scale, mobile wireless sensor network. Each node is a stand-alone system that consists of a suite of sensors, a transceiver, and a processor. Building on research in the areas of wireless sensor networks and mobile ad hoc networks, this...
Medium access control for a distributed cooperative wireless sensor network is examined. Using a quality-of-service approach, the sensor node traffic (control and data packets) within these cooperative networks is characterized. A novel medium access control mechanism, cooperative wireless sensor medium access control (CWS-MAC), is proposed to meet the requirements of the control and data traffic...
A new modulation technique that uses four orthonormal basis functions is proposed. Using four orthonormal basis functions provides an advantage over most traditional modulation techniques such as quadrature phase shift keying and quadrature amplitude modulation that only possess two degrees of freedom. Hyper phase shift keying offers an increase in error performance over these modulation techniques...
A beamforming approach can be used in a wireless sensor network (WSN) to increase the effective communication range of the network. In this paper, the impact on array performance of node position deviations with respect to the ideal array element locations is examined and a distributed beamforming algorithm is proposed to compensate for these position deviations. Simulation results are provided to...
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