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There has been recent extensive research on integrating cellular networks and ad hoc networks to overcome the limitations of cellular networks. Although several schemes have been proposed to use such hybrid networks to improve the performance of individual multicast groups, they do not address quality of service (QoS) issues when multiple groups are present. This paper, on the other hand, considers an interesting scenario of hybrid networks when an ad hoc network cannot accommodate all the groups and a base station has to select a subset of groups to optimize its bandwidth savings and maximize the utilization of the ad hoc network while providing QoS support for multicast users. In this paper, a network model for multicast admission control that takes wireless interference into account is developed, the group selection problem is formulated as a multidimensional knapsack problem, and an integer linear programming (ILP) formulation and a polynomial-time dynamic algorithm are proposed. A distributed implementation of the dynamic algorithm in real systems is also examined. Simulation studies demonstrate that the dynamic algorithm is able to achieve very competitive performance under various conditions, in comparison with the optimal solution computed by the ILP approach. [ABSTRACT FROM AUTHOR]

Capturing the flow of information between cities is a challenging task. Historically, flow analyses have focused on goods, capital, and people, all of which can serve as proxies for estimating the volume of spatial interaction between places. However, with the advent of the Internet and its ability to both facilitate and accelerate the exchange of information, it is somewhat surprising that so few studies have examined the geographical characteristics of Internet flows. Aside from the initial challenges associated in acquiring network flow data, there are additional constraints inhibiting such efforts, including privacy concerns, the geographic rectification of flows, and the ability to manage and visualize massive datasets. The purpose of this paper is to outline a basic methodology for capturing Internet flow data and to provide a brief empirical analysis of these data for the Internet2 network in the United States. Results suggest that asymmetries exist between ingress and egress connectivity and flows throughout the United States. [ABSTRACT FROM AUTHOR]

A new multicarrier system, termed multisymbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM), is proposed, in which one cyclic prefix (CP) is used for multiple OFDM symbols. The original motivation for the MSE-OFDM proposal is to reduce the redundancy due to the CP in static-channel environments. The authors then found that an alternative implementation of the system can be used to improve the robustness to frequency offset and reduce the peak-to-average power ratio (PAPR). Equalization and demodulation algorithms for the MSE-OFDM system are proposed. A new preamble and the corresponding frequency-offset and channel estimation techniques are studied for the MSE-OFDM system. Using the proposed MSE-OFDM preamble, the joint maximum likelihood (ML) estimation of the frequency offset and the channel impulse response (CIR) is investigated in this paper. Possible ways to reduce the joint estimation complexity, including exploitation of the preamble structure, approximation of the joint ML estimator, and fast Fourier transform (FFT) pruning, are discussed. The performance of the proposed MSE-OFDM systems and channel estimators are analyzed and verified through numerical simulations. An analysis on the bandwidth efficiency, the performance with frequency offset, and the PAPR of the MSE-OFDM system are also presented. [ABSTRACT FROM AUTHOR]

Joint scheduling and power control schemes have previously been proposed to reduce power dissipation in wireless ad hoc networks. However, instead of power consumption, throughput is a more important performance concern for some emerging multihop wireless networks, such as wireless mesh networks. This paper examines joint link scheduling and power control with the objective of throughput improvement. The MAximum THroughput link Scheduling with Power Control (MATH-SPC) problem is first formulated and then a mixed integer linear programming (MILP) formulation is presented to provide optimal solutions. However, simply maximizing the throughput may lead to a severe bias on bandwidth allocation among links. To achieve a good tradeoff between throughput and fairness, a new parameter called the demand satisfaction factor (DSF) to characterize the fairness of bandwidth allocation and formulate the MAximum Throughput fAir link Scheduling with Power Control (MATA-SPC) problem is defined. An MILP formulation and an effective polynomial-time heuristic algorithm, namely, the serial linear programming rounding (SLPR) heuristic, to solve the MATA-SPC problem are also presented. Numerical results show that bandwidth can be fairly allocated among all links/flows by solving the MILP formulation or by using the heuristic algorithm at the cost of a minor reduction of network throughput. In addition, extensions to end-to-end throughput and fairness and multiradio wireless multihop networks are discussed. [ABSTRACT FROM AUTHOR]

In this paper we have investigated Microstrip line fed semi circular printed monopole antenna, which is basically printed microstrip antenna with etched ground plane for UWB applications. In particular we have simulated circular patch monopole antenna and then after etched some part of the radiating patch in order to make semi circular antenna with good performance for UWB communication. While doing simulation study, a simple rectangular microstrip line is used for feeding the printed monopole antenna. Finally the simulated antenna is having frequency bandwidth under -10dB return loss is ranging from 2.8 GHz to 15 GHz. This semi circular printed monopole antenna works well for the whole UWB frequency band 3.1-10.6GHz. [ABSTRACT FROM AUTHOR]

Abstract: Two case studies explore the reciprocal influence between technological change and Internet governance. Both focus on the use by Internet service providers of a new capability known as deep packet inspection (DPI). DPI was used by major network operators in the U.S. and Canada to block or restrict the speed of peer to peer file sharing traffic by their customers. In both cases, DPI implementations led to public protests, litigation and major regulatory proceedings. In both cases, network neutrality norms were used to challenge DPI deployments. The paper''s descriptive comparison is supplemented by quantitative data drawn from the use of Glasnost, a network test that allows third parties to detect BitTorrent throttling via DPI. The paper asks whether the use of DPI by ISPs disrupted the way the Internet is regulated, and whether political and institutional factors alter or constrain DPI use. It finds that the power to shape traffic flows redistributes control among actors in the Internet ecosystem, generating broad political economy debates about efficiency, fairness, innovation and transparency. But the actual results of those conflicts are indeterminate, reflecting institutional and historical contingencies. [Copyright &y& Elsevier]

Abstract: This paper presents a refined description of the wave climate observed in a Portuguese location for marine energy projects. The data used in this case study were derived from 3-month in situ measurements carried out using three directional buoys that have been deployed simultaneously – yet independently (various buoy types and water depths) – on the Atlantic coast in the neighbourhood of Figueira da Foz. Two ways of reporting the statistics were adopted. In the first one, each recorded sea state was summarized as a set of global parameters accounting for energy, mean frequency and direction, spectral bandwidth and directional spreading related to the main ongoing wave field considered as unimodal. In the second one, each sea state has been decomposed into its own wave components – swells and wind-sea – which are characterised separately and individually by the same set of parameters as previously. Besides the adopted data processing techniques and the illustration of such thorough wave climate description modes, the paper also addresses the advantages and limits of each adopted parameterization in the frame of simultaneous and independent in situ wave measurements. [Copyright &y& Elsevier]

Purpose – The last decade has seen increasing advocacy for, and interest in the use of white space in the broadcasting bands by providers of wireless broadband services. This paper aims to discuss the scope in Australia for "symbiotic" and "invasive" white space devices to operate in the UHF band after digital switchover and speculate about longer term trends.Design/methodology/approach – The authors draw from their analysis of recent regulatory decisions to explain how the parameters established for channel planning naturally conduce to the development of large white spaces. They then identify emerging opportunities for white space usage in the reduced UHF band allocated to digital television services as well as in nearby guard bands.Findings – The article's analysis suggests that there is considerable scope for white space devices to operate in Australia – even in the context of a reduced UHF band following analog switch off. Furthermore, the authors argue that the development of complementary business models could see off any perceived conflict between intensive white space usage and the long-term benefit of both broadcasters and telecommunications operators.Practical implications – It is timely for proponents of white space usage to establish regulatory arrangements that will allow intensive use of those white spaces. Current FCC proposals to base the regulatory framework on spectrum co-sharing between broadcasters and white space broadband providers may lead to similar, yet distinct, opportunities in the USA as well.Originality/value – There is a surprising paucity of published information worldwide regarding white space regulation. This article provides an in-depth discussion of the main parameters driving white space opportunity. [ABSTRACT FROM AUTHOR]

In this paper, we have designed an RFID reader receiver system for improving the performance of the passive Tag-based 908.5–914 MHz RFID reader, and analyzed the system performance vis-à-vis frequency, reader, and tag properties. The commercial receiver system causes a loss in sensitivity because of its 24 capacitors and six inductors. To improve the overall sensitivity of the receiver, we have designed a system using a circulator, low noise amplifier (LNA) and a SAW filter. The experimental results show that the use of a circulator to separate the Tx/Rx paths eliminates interference, the LNA improves the sensitivity of the Rx module and SAW filter eliminates the noise and spurious components in the received signal. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a bandwidth increasing technique using a modified ground plane with diagonal edges for the design of compact antennas. The proposed low-cost, compact-size circular patch antenna on 3 cm x 5.1 cm printed circuit board (FR-4) is designed and validated through simulations and experiments. Results show that with diagonal cuts at corners of the ground plane, the enhanced bandwidth can be tunable depending on the removed area. Return losses of minus 17 and minus 30 dBs for the first and second resonant frequencies, respectively, can be achieved when the depth of the diagonal cut is at optimum value of five mm, providing an 18.13% wider bandwidth (2.95-12.615 GHz) than the Federal Communication Commission (FCC) standard. [ABSTRACT FROM AUTHOR]

This paper deals with channel acquisition and tracking in the uplink of a multicarrier code division multiple access (MC-CDMA) system. The transmission medium is characterized by multipath propagation, and the goal is to estimate the channel frequency response and the noise-power of each active user. Channel acquisition is performed jointly with the noise-power estimation following two different approaches. The first assumes independently faded subcarriers, while the second exploits the fading correlation across the signal bandwidth to improve the system performance. Both schemes are based on the maximum likelihood (ML) criterion and exploit some training blocks carrying known symbols. Channel tracking is pursued through least mean square (LMS) techniques using data decisions provided by a partial parallel interference cancellation (PPIC) receiver. Numerical results are given to highlight the effectiveness of the proposed methods and to present comparisons with other existing solutions. [ABSTRACT FROM AUTHOR]

In this paper, a new cross-layer communication protocol for vehicular Internet access along highways is introduced. The objective of the new Controlled Vehicular Internet Access (CVIA) protocol is to increase the end-to-end throughput while achieving fairness in bandwidth usage between road segments. To achieve this goal, the CVIA protocol eliminates contention in relaying packets over long distances. CVIA creates single-hop vehicle clusters and mitigates the hidden node problem by dividing the road into segments and controlling the active time of each segment. Using an analytical throughput estimation model, the protocol parameters are flue-tuned to provide fairness among road segments. Simulation results confirm that the proposed CVIA protocol provides higher throughput and better fairness in multihop data delivery in vehicular networks when compared with purely IEEE 802.11-based protocols. [ABSTRACT FROM AUTHOR]

Digital terrestrial broadcasting services are in the Japanese UHF band of 470 to 770 MHz. The bandwidth of the UHF-TV channel is 6 MHz. The batwing radiator, which is at the heart of the super-turnstile antenna system for FM and VHF-TV broadcasting, has broadband characteristics. In this paper, we investigated a modified batwing antenna for UHF digital terrestrial broadcasting. The characteristics of the two- and four-element modified batwing antennas, with an infinite or a finite wire reflector, were calculated using NEC-WIN Pro. We evaluated the characteristics of these antennas in the Japanese UHF-TV broadcasting band. A broadband input impedance and high gain were obtained in the calculation and the measurement. A four-plane arrangement of parallel batwing antennas was also examined for directionality. The batwing element was arranged in parallel,and the feed interval was a half-wavelength. High gain and wideband characteristics were obtained with simple power-supply construction. This antenna has sufficient characteristics for use as the transmitting antenna for digital terrestrial broadcasting stations and repeater stations in the Japanese UHF band. [ABSTRACT FROM PUBLISHER]

Statistics of radio frequency interference (RFI) observed in the band 1398–1422 MHz during an airborne campaign in the United States are reported for use in analysis and forecasting of L-band RFI for microwave radiometry. The observations were conducted from September to October 2008, and included approximately 92 h of flight time, of which approximately 20 h of “transit” or dedicated RFI observing flights are used in compiling the statistics presented. The observations used include outbound and return flights from Colorado to Maryland, as well as RFI surveys over large cities. The Passive Active L-Band Sensor (PALS) radiometer of NASA Jet Propulsion Laboratory augmented by three dedicated RFI observing systems was used in these observations. The complete system as well as the associated RFI characterization approaches are described, along with the resulting RFI statistical information and examinations of specific RFI sources. The results show that RFI in the protected L-band spectrum is common over North America, although the resulting interference when extrapolated to satellite observations will appear as “low-level” corruption that will be difficult to detect for traditional radiometer systems. [ABSTRACT FROM AUTHOR]

Abstract: Superconducting RF (SRF) cavities are key components of modern linear particle accelerators. The National Superconducting Cyclotron Laboratory (NSCL) is building a 3MeV/u re-accelerator (ReA3) using SRF cavities. Lightly loaded SRF cavities have very small bandwidths (high Q) making them very sensitive to mechanical perturbations whether external or self-induced. Additionally, some cavity types exhibit mechanical responses to perturbations that lead to high-order non-stationary transfer functions resulting in very complex control problems. A control system that can adapt to the changing perturbing conditions and transfer functions of these systems would be ideal. This paper describes the application of a control technique known as “Active Disturbance Rejection Control” (ARDC) to this problem. [Copyright &y& Elsevier]

Abstract: In this paper, the effect of microwave absorbing material-based (MAM) substrate on the absorption properties of fractal frequency selective surface (FSS) absorbers was investigated in detail. The fractal shapes were proposed to construct the schematic diagrams of the FSS unit cell. The absorption properties of the absorber samples containing different substrates, including FR-4dielectric substrate and MAM-based substrate, were exhibited via the Naval Research Laboratory (NRL)-arch method, respectively. Then the power loss density distributions of the absorbers were illustrated by the finite integration technology (FIT) method to obtain an insight of the physical picture into the absorption properties. The results indicate that with the increase of the substrate thicknesses, the FR-4-based FSS absorbers could achieve the strongest absorbing performance at a certain thickness. However, employing the MAM-based substrate to replace the FR-4 substrate with the same substrate thickness enhances the absorbing properties greatly, including the peak values and the bandwidths. As a result, the way of introducing the MAM-based substrates instead of the traditional dielectric substrates provides a potential practical application in device miniaturization. [Copyright &y& Elsevier]

The article discusses several key issues in designing coscheduling algorithms for clusters in the U.S. The availability of high bandwidth and low-latency networks supported by efficient user-level communication protocols has made high performance computing clusters an attractive and cost effective alternative to traditional multiprocessor systems. These clusters are often used either as dedicated Beowulf systems for running real-world parallel simulations systems for running parallel jobs. The experimental results show that the blocking-based coscheduling scheme has better tolerance to system workload variation compared with the spin-based schemes and overall the blocking-based coscheduling scheme seems a better choice for non-dedicated Linux clusters.

In this article, we revisit the problem of how to construct better nonparametric confidence intervals for the conditional quantile function from an optimization perspective. We apply the fully data‐driven bias correction procedure based on local polynomial smoothing to estimate the conditional quantile. To account for the effect of the estimated bias, we apply an asymptotic framework that the ratio of the bandwidth to the pilot bandwidth tends to some positive constant rather than zero as the sample size grows. We derive an alternative asymptotic normality of the proposed bias‐corrected quantile estimator as well as a new asymptotic variance formula. Based on theoretical results, two new pointwise confidence intervals are constructed through resampling strategies. Extensive simulation studies show that our proposed confidence intervals enjoy better performance than other competitors in terms of coverage probabilities and interval lengths and are not sensitive to the choice of bandwidth. Finally, our proposed procedure is further illustrated through United States' natality birth data in 2017. [ABSTRACT FROM AUTHOR]

The article presents information on broadband localism wherein municipalities in the U.S. join with local anchor institutions and private broadband service providers to minimise the digital divide and promote novel public-minded service models. It also informs that the speed and bandwidth capacity of local network infrastructure governs users' media consumption habits.

Empirical cost models for wireline broadband circuits are used to test whether economies of scale exist in rural areas and whether new Ethernet technology lowers the unit cost of broadband transportation. Previous studies have shown small or nonexistent economies of scale for wireless technology. Results from earlier studies also demonstrated economies of scale for voice-only wireline networks which diminished with network size and were fully exploited for large networks. To our knowledge presence of economies of scale for wireline broadband networks has not been tested, certainly not in rural United States. We use data supplied by more than 500 rural local exchange carriers and find economies of scale for small rural wireline broadband providers. Market size limitations appear to prevent rural telephone companies from fully exploiting unit cost savings. The data also show increasing capacity over existing broadband connections is subject to substantial economies of scale, but such economies diminish quickly as bandwidth capacity increases. The data do not support the hypothesis that Ethernet technology reduces broadband transmission cost. [ABSTRACT FROM AUTHOR]

The Articulation Index (AI) and Speech Intelligibility Index (SII) predict intelligibility scores from measurements of speech and hearing parameters. One component in the prediction is the 'importance function,' a weighting function that characterizes contributions of particular spectral regions of speech to speech intelligibility. Previous work with SII predictions for hearing-impaired subjects suggests that prediction accuracy might improve if importance functions for individual subjects were available. Unfortunately, previous importance function measurements have required extensive intelligibility testing with groups of subjects, using speech processed by various fixed-bandwidth low-pass and high-pass filters. A more efficient approach appropriate to individual subjects is desired. The purpose of this study was to evaluate the feasibility of measuring importance functions for individual subjects with adaptive-bandwidth filters. In two experiments, ten subjects with normal-hearing listened to vowel-consonant-vowel (VCV) nonsense words processed by low-pass and high-pass filters whose bandwidths were varied adaptively to produce specified performance levels in accordance with the transformed up-down rules of Levitt [(1971). J. Acoust. Soc. Am. 49, 467-477]. Local linear psychometric functions were fit to resulting data and used to generate an importance function for VCV words. Results indicate that the adaptive method is reliable and efficient, and produces importance function data consistent with that of the corresponding AI/SII importance function. [ABSTRACT FROM AUTHOR]

The concept is to use a grounded co-planar waveguide (GCPW) to enhance useful characteristics of a fractal antenna. In this case 9.54 dB return loss and input impedance bandwidths are increased. The specific candidate antennas are printed fractal monopoles such as the Penta-Gasket-Koch (PGK) antenna. These topical antennas are used to compare a coaxial fed system with GCPW-fed system. A PGK is applied for two bands germane to ultra-wideband (UWB). These are 5.35-7.35 GHz and 10.07 to 11 GHz (refer to VSWR<2). A modified PGK is presented with a wideband input match from 4.25 to 11 GHz (refer to VSWR<2). Results suggest that these antennas are possible candidates for Federal Communications Commission (FCC) UWB radio short fat pipe systems with time-domain analysis indicating reduced ringing for impulse excitation over the proposed FCC bandwidth. In addition, the correlation between the time-domain transmitting antenna's input signal and the receiving conventional PGK antenna output signal is obtained which demonstrates approximately 89% antipodal resemblance. The modified PGK antenna improves the antipodal resemblance up to 95% [ABSTRACT FROM AUTHOR]

In this study, a new method for digitizing a combination of different analog signals occupying significantly different bandwidths and having a very high dynamic range is proposed and analyzed. Since it is based upon signal-prediction/cancellation principles, it is referred to as adaptive prediction and cancellation digitization (APCD) method and is applied to various families of signals simultaneously received by a multistandard software radio (SWR) base-station receiver. It is shown theoretically and by means of computer simulations that the APCD method can effectively reduce the high dynamic range of the signals before digitization takes place. Hence, the stringent analog-to-digital-converter (ADC) resolution requirements imposed by the operation of such SWR base-station receivers can be significant relaxed. The signal dynamic-range reduction is achieved by applying appropriate signal processing techniques, e.g., autoregressive (AR) and periodic autoregressive (PAR) prediction. Such techniques allow accurate prediction and subsequent cancellation of high-power narrowband signals present among the composite received analog signal. As these signals usually have cyclostationary statistical characteristics, analysis and performance evaluation of AR and PAR predictors, when used to predict cyclostationary signals, were presented. A new adaptive algorithm for implementing the PAR predictor is also proposed, and its validity is justified by theoretical analysis as well as by various performance evaluation results obtained by means of computer simulations. [ABSTRACT FROM AUTHOR]