Desired Bandwidth Research Articles

Compact size planar folded pifa design for mobile handset

A printed compact size folded inverted-F antenna with simple configuration for mobile handset operating within the global system for mobile communication/personal communication system/digital communication system bands is initially proposed.To additionally cover the wireless local-area network frequency spectrum at 2.4 GHz, a narrow stub is protruded from the printed shorting wall. The excitation of these operating bands with desirable bandwidth is achieved by feeding a 50-Ω microstrip line to the folded radiating element through a via hole. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1045–1050, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25919

Dimensioning internet protocol television video on demand services

The Internet Protocol Television (IPTV) subscription rate has increased steadily since the introduction of IPTV Video on Demand (VoD) services. We have developed a model to determine the optimum deployment strategy for delivering IPTV VoD network services from the IPTV service providers' perspective. The analysis technique in this paper helps us determine how to support a particular IPTV VoD deployment having a given number of customers that each must receive a contracted Quality of Experience (QoE). The main QoE measures considered are server waiting time, one-way minimum delay and access network bandwidth consumption. All these models are made considering heterogeneous network conditions. The QoE models will help service providers make network deployment decisions including the number of servers, distance of servers from a community and desirable access network bandwidth capacity. Copyright © 2011 John Wiley & Sons, Ltd.

Integrated Design and Control of Flexure-Based Nanopositioning Systems — Part II: Application Case Study

AbstractFlexure-based mechanisms contain slender beam-like modules that undergo linear elastic deflections over small ranges of motion at nanoscale resolutions. They are hence often used as bearing elements in nanopositioning systems, along with precision actuator and sensing subsystems. An integrated design and control methodology proposed in Part I of this paper proposed varying design topology and controller order for meeting performance requirements of the closed-loop controlled system. A detailed set of steps was given for meeting requirements such as a desired static or dynamic load-capacity, bandwidth, or range of motion. In this part of the paper, an application case study for a practical precision positioning and alignment system is worked out to illustrate the steps involved in using the proposed methodology. The details of optimization problem formulation and solutions for design and control are presented. The outcome of the exercise is a novel design topology, with it shape and size optimized, and a controller synthesized such that a desired control bandwidth and design requirements of strength and modal separation are met.

Integrated Design and Control of Flexure-Based Nanopositioning Systems — Part I: Methodology

AbstractFlexure-based mechanisms, also referred to as flexures, are widely being used as motion-guidance, or bearing, elements in applications requiring multi-degree-of-freedom positioning and alignment. Unlike friction-bearings (such as sliding or rolling contact bearings), flexures can be designed to offer, to a large extent, reliable linear elastic motion with a high resolution (on the order of nanometers) over small ranges of motion (on order of micrometers). Example applications include positioning a probe or sample in atomic force microscopy, alignment of tool and sample in stamping processes, and fine-positioning of wafers and masks in semiconductor manufacturing. These applications are often required satisfy critical functional requirements, such as load-capacity, bandwidth, resolution, and range. A systematic approach is needed to simultaneously address the design and control challenges involved, starting from the initial design concept generation stage to the final control implementation and testing. In this paper, we present an integrated design and control method for implementing flexure-based nanopositioning systems. We discuss the need for varying design topology and order of a controller in design and control optimization. An automation engine generates a set of flexure-based design topologies and also controllers of varying order in the optimization. A simple 1-DOF example is worked out to illustrate the steps involved in using this methodology. The outcome of the exercise is a novel design topology, with it shape and size optimized, and a controller synthesized such that a desired control bandwidth and design requirements of strength and modal separation are met.

InstantLeap: an architecture for fast neighbor discovery in large-scale P2P VoD streaming

In large-scale peer-to-peer (P2P) video-on-demand (VoD) streaming applications, a fundamental challenge is to quickly locate new supplying peers whenever a VCR command is issued, in order to achieve smooth viewing experiences. For many existing commercial systems which use tracker servers for neighbor discovery, the increasing scale of P2P VoD systems has overloaded the dedicated servers to the point where they cannot accurately identify the suppliers with the desired content and bandwidth. To avoid overloading the servers and achieve instant neighbor discovery over the self-organizing P2P overlay, we design a novel method of organizing peers watching a video. The method features a light-weight indexing architecture to support efficient streaming and fast neighbor discovery at the same time. InstantLeap separates the neighbors at each peer into a streaming neighbor list and a shortcut neighbor list, for streaming and neighbor discovery respectively, which are maintained loosely but effectively based on random neighbor list exchanges. Our analysis shows that InstantLeap achieves an O(1) neighbor discovery efficiency upon any playback "leap" across the media stream in streaming overlays of any size, and low messaging costs for overlay maintenance upon peer join, departure, and VCR operations. We also verify our design with large-scale simulation studies of dynamic P2P VoD systems based on real-world settings.

Frequent layer switching for perceived quality improvements of coarse-grained scalable video

Scalable video is an attractive option for adapting the bandwidth consumption of streaming video to the available bandwidth. Fine-grained scalability can adapt most closely to the available bandwidth, but this comes at the cost of a higher overhead compared to more coarse-grained videos. In the context of VoD streaming, we have therefore explored whether a similar adaptation to the available bandwidth can be achieved by performing layer switching in coarse-grained scalable videos. In this approach, enhancement layers of a video stream are switched on and off to achieve any desired longer term bandwidth. We have performed three user studies, two using mobile devices and one using an HDTV display, to evaluate the idea. In several cases, the far-from-obvious conclusion is that layer switching is a viable way of achieving bit-rate savings and fine-grained bit-rate adaptation even for rather short times between layer switches, but it does, however, depend on scaling dimensions, content and display device.

An optimized scheduling scheme in OFDMA WiMax networks

AbstractThis paper proposes an optimized scheduling scheme in OFDMA‐based WiMax networks to achieve both optimized system throughput and a complete QoS implementation for various types of traffic flows. Our scheduling scheme includes two components, one is the resource allocation for each user; the other is the QoS scheduling for various traffic sessions. Specifically an optimization problem is formulated to distribute all OFDMA channel resource among different competing users by exploiting the transmission adaption and multiuser diversity on each traffic channel. The optimized resource allocation can also be processed under different constraints to achieve different performance metrics. To ensure the WiMax QoS performance, we perform the resource allocation in a priority manner with respect to the different types of QoS requirements and get a desired transmission bandwidth for each user. Based on it we further schedule different traffic sessions at each user with respect to a proper admission control mechanism. The relevant solution and algorithms for our proposed scheduling scheme are presented in detail. Both the theoretical analysis and simulation results show that our scheme can achieve the key performance objectives such as complete QoS requirements, high channel transmission efficiency and optimal throughput over the whole OFDMA WiMax system. Copyright © 2009 John Wiley & Sons, Ltd.

Probabilistic Modeling and Analysis of DoS Protection for the ASV Protocol

The Adaptive Selective Verification (ASV) protocol was recently proposed as an effective and efficient DoS countermeasure within the shared channel model, in which clients and attackers probabilistically share communication bandwidth with the server. ASV has been manually shown to satisfy some desirable availability and bandwidth consumption properties. Due to the probabilistic nature of the protocol and its underlying attacker model, it is intrinsically difficult to build a faithful model of the protocol with which one may automatically verify its properties. This paper fills the gap between manual analysis and simulation-based experimental analysis of ASV, through automated formal analysis. We describe a formal model of ASV using probabilistic rewrite theories, implemented in a probabilistic extension of Maude, and show how it can be used to formally verify various characteristics of ASV through automated statistical quantitative model checking analysis techniques. In particular, we formally verify ASV's connection confidence theorem and a slightly more general bandwidth consumption theorem of ASV. This is followed by a statistical comparison of ASV with non-adaptive selective verification protocols. We conclude with remarks on possible further development and future work.

LIMITS ON PRODUCTION OF NARROW BAND PHOTONS FROM INVERSE COMPTON SCATTERING

In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry.

Input impedance‐tuning slots of PIFA antennas

AbstractInput impedance‐tuning methods are proposed for antenna designs of mobile communications devices. The proposed method can be applied to input impedance‐tuning of single‐band, dual‐band, and multiband planar inverted‐F antenna. The prominent feature of this impedance‐tuning method is to use an inductive‐tuning slot or a capacitive‐tuning slot, rather than the width of the grounding and feeding strips and the gap between the grounding and feeding strips, to get desirable impedance matching and bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1464–1467, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22419

Wideband Properties of Fractal Bowtie Dipoles

This paper explores constructing fractal bowtie dipoles using the pattern of the fractal binary tree. To achieve desirable wide impedance bandwidth, structural parameters of fractal bowtie antennas are optimized in an automated design, making use of the Genetic Algorithm (GA) in conjunction with NEC (Numerical Electromagnetic Codes) and cluster parallel computation. Several design results are presented and exhibit quite promising wideband properties. Their simulated 2:1 VSWR impedance bandwidths range from 3.2:1 to 5.3:1, which far surpass the bandwidth of a conventional bowtie dipole.

Utilizing Sensor Arrays to Attain High-Operating Bandwidth

Proposed in this paper is a methodology for the design of a sensor array of small bandwidth passband sensors (sensors with small bandwidth but different bandwidths) to attain a high operating bandwidth. In certain control applications, it is necessary that a high bandwidth sensor be used for feedback efficiency. The design of a single sensor with the desired high bandwidth may not be easy and economically feasible. A new approach, which recommends the use of an array of small bandwidth pass-band sensors in place of a single sensor of high bandwidth is proposed. It is shown that the idea of sensor arrays can be utilized to obtain a cost effective and efficient solution to the problem posed. The proposed sensor array that consists of multiple sensors with possible overlapping operating regions as defined by their pass-bands requires that an effective fusion technique be used to unite multi-sensor data. A multi-sensor data fusion scheme using Frequency Response Methods is developed to facilitate the possible implementation of proposed sensor arrays.

Holographic interference filters for infrared communications

We demonstrate that high-quality interference filters for the wavelength range 1300-1600 nm can be holographically fabricated in DuPont HRF-800X001 photopolymer material by use of visible laser illumination. We also summarize a chain-matrix technique, which we call thin-film decomposition, that is useful for modeling multilayer films with an arbitrary index profile n(z). We use the thin-film-decomposition technique to create design curves that allow one to choose the proper exposure angle and film thickness with which to fabricate a holographic interference filter with a desired transmission efficiency and bandwidth at a particular wavelength. These curves are of general utility and are not confined to any particular holographic recording medium. Excellent agreement between theory and experiment is found.

Bandwidth of a hot-electron bolometer mixer according to the hotspot model

The hotspot model has been used to simulate the intermediate frequency bandwidth of a lattice cooled NbN hot-electron bolometer mixer. The results of simulation suggest that with the increase of the bias current, the bandwidth decreases, passes the minimum, and recovers again. The appearance of the bandwidth minimum correlates with experimentally observed noise maximum at the mixer output that drastically reduces the sensitivity of a relevant receiver. At large bias currents the bandwidth exceeds the reciprocal electron cooling time. Since the noise temperature also increases with the bias current, a compromise between the desirable bandwidth and acceptable noise temperature can be reached by varying the bias current.

Wide-band airborne radar operating considerations for low-altitude surveillance in the presence of specular multipath

Reliable detection of low-altitude platforms while simultaneously maintaining a desired search rate can be extremely difficult due to the presence of multipath. Wide-band operation in combination with frequency diversity is a sensible approach to not only mitigate, but in some cases exploit multipath channel characteristics. While a great deal of knowledge exists for characterizing the frequency dependencies of complicated multipath channels, relatively little attention has been given to examining how this knowledge could be exploited with wide-band radar sensors. The utilization of multipath channel characteristics is considered for the scenario of an airborne wide-band radar sensor performing low-altitude surveillance in a maritime environment. A brief overview of applicable multipath phenomenology is presented leading to a description of the propagation conditions selected for the construction of a representative channel. A generalized wide-band model of the sensor engagement applicable to the resolved and unresolved domains of the interference regime is utilized in combination with the simulated channel. Wide-band short pulse and linear frequency modulation waveforms are employed to consider waveform modulation characteristics in combination with desirable sensor bandwidth and frequency diversity for nominal operation at X-band. A brief discussion on implementation possibilities is also included.

Dissipative Feedback Control of a Reverberant Enclosure Using a Constant Volume Velocity Source

Loudspeakers are commonly used as actuators in active noise control applications. In this work, a loudspeaker is compensated so that it approximates a constant volume velocity source over the piston mode frequency range (up to approximately 600 Hz). This moves the speaker dynamics out of the desired control bandwidth (20 Hz–500 Hz). A static gain feedback controller using the compensated speaker is applied to a rigid-wall enclosure to reduce the acoustic potential energy of the system while being subjected to low frequency broadband noise. The results are compared to the performance of a similar control law using an uncompensated speaker, and a model based H2 optimal controller. The results indicate that the controller using the compensated speaker offers definite advantages in terms of stability and performance, while requiring a minimal amount of control effort.

Precision Tracking Control of Discrete Time Nonminimum-Phase Systems

In this paper, a precision tracking control scheme for linear discrete time nonminimum-phase systems is proposed. This control scheme consists of a preview filter, a tracking-performance filter, a command feedforward controller, and a feedback controller. A command feedforward controller, whose design is based on the minimal order inverse model of the plant being controlled, will result in a completely decoupled system. The preview filter is introduced to compensate the phase and gain errors induced by the nonminimum phase zeros or lightly damped zeros of the system. Using the command feedforward controller along with the proposed preview filter, the tracking performance of the proposed control scheme can be characterized by the frequency response of the tracking-performance filter. For the design of the preview filter, a generalized Nth order preview filter and its associated penalty function that quantifies the tracking error of a design are defined. It is shown that, given the desired bandwidth and the order of the preview filter, the optimal solution for the design of the preview filter can be obtained explicitly. The proposed control scheme together with the optimal preview filter is shown to be very effective in achieving precision tracking control of discrete time MIMO nonminimum phase systems. It is also shown that the tracking performance is improved as the order N of the preview filter is increased.

DQDB performance under sustained overload with bandwidth balancing and multiple requests outstanding

The performance of an enhanced DQDB protocol with Bandwidth Balancing (BWB) and Multiple Requests Outstanding (MRO) under sustained overload is examined by means of simulation. It is demonstrated that MRO may provide a desired bandwidth apportionment without using BWB, for a very specific case of concentrated sources; otherwise. MRO cannot be used without BWB to obtain the desired bandwidth allocation. When used together with, and in the same ratio as, the BWB, MRO speeds up the convergence towards the steady state bandwidth apportionment intended by BWB.

Field Corn, Corn Rootworm Larval Control, 1992

Abstract Rootworm planting-time, soil-insecticide test plots were established at 5 IA locations in 1992. Two of these locations were also used for cultivation-time insecticide tests. The soil type at Ames and Newell was loam; Crawfordsville, Sutherland, and Mt. Union was silt loam. The experimental design was a randomized complete block with 4 replications for the root-protection trials (registered and numbered products) and 8 replications for the yield trials (registered and EUP products). All treatments were applied to single 50-ft length row with 30-inch row spacing. Granular insecticide formulations were applied with modified Noble metering units that had been laboratory-calibrated to accurately deliver material at a tractor speed of 4 mph. The applicators were mounted on a 4-row John Deere Max-Emerge 7100 integral planter. Each row was constantly monitored to ensure that insecticide was being correctly applied at all times. Planter-mounted drag chains were used for insecticide incorporation. Granular cultivation-time insecticide applications were made with electrically-driven Noble units mounted on the tool barof a 2-row, rear-mounted cultivator. Plastic tubes, positioned directly in front of the cultivator sweeps, directed the insecticide granules to both sides of the corn row for basal treatments. Liquid insecticides were applied with a small-plot bicycle sprayer. Two 8003E nozzles, 1 on each side of the corn row, created the desired band width around the base of the plants. Liquid application rate was 10 gal/acre at 10 psi. Early cultivation-time applications (7-10 d prior to cultivation) consisted of a 15-inch band with no incorporation. All other liquid applications were done just prior to cultivation with a 7-inch band. Chemical phytotoxicity was checked in early Jun by taking stand counts from 1/1000 acre and measuring the height of 10 consecutive plants from each treatment. Evaluation of root damage was started in mid-Jul, but due to excessive rainfall, the root ratings were not completed until mid-Aug. Rootworm feeding was evaluated by digging 5 roots from each treatment row and rating them on the Iowa 1-6 scale (1 equal to no damage or only a few minor feeding scars, and a 6 rating equal to 3 or more nodes of roots completely destroyed). Lodging counts were taken at harvest time. A plant was considered lodged if the angle between the base of the plant and the ground was 45° or less. Stand counts (number plants per 1/1000 acre) were taken in the yield plots at harvest time. Yields were measured by hand harvesting 1/1000 acre from each treatment. To determine treatment differences, data were analyzed using ANOVA and means were separated with REGWQ.

Design of attitude and rate command systems for helicopters using eigenstructure assignment

This paper describes the use of eigenstructur e assignment in the direct design of attitude and attitude rate command systems for helicopter flight control. Eigenvalue assignment is used to achieve desired bandwidth based on the handling qualities specifications, and eigenvector assignment is used to achieve decoupling of lateral, longitudinal, heave, and yaw modes and the desired command-response characteristics. Eigenstructure techniques are also used to design a state estimator that gives desired closed-loop frequency response. The stability robustness of the control system is evaluated with respect to an error model that includes rotor, actuator, flexure, and sensor dynamics and computational and sampling delays in the flight control system. The controlled helicopter is shown to exhibit both good frequency and time-response characteristics. Nomenclature Scalars g = acceleration of gravity m = number of controls n = number of states p — roll rate, rad/s q — pitch rate, rad/s