WorldWideScience

Sample records for wimax radio-over-fiber links

  1. High Capacity Radio over Fiber Transmission Links

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio

    confirmed that this configuration provides high linear end-to-end transmission links and is capable of transparent transport of high spectral efficient modulation formats. Furthermore, this thesis introduces a novel approach for the generation and detection of high speed wireless signals in mm-wave......This thesis expands the state-of-the-art on the detection of high speed wireless signals using optics. Signal detection at speeds over 1 Gbps at carrier Radio Frequency (RF) ranging from 5 GHz to 100 GHz have been achieved by applying novel concepts on optical digital coherent receivers....... This achievement has satisfied the requirements on transmission robustness and high capacity of next generation hybrid optical fibre-wireless networks. One important contribution of this thesis is the novel concept of photonic downconversion with free-running pulsed laser source for phase modulated Radio...

  2. 225m Outdoor W-Band Radio-over-Fiber Link Using an Optical SFP+ Module

    DEFF Research Database (Denmark)

    Rommel, Simon; Rodríguez Páez, Juan Sebastián; Chorchos, Łukasz

    2016-01-01

    A W-band radio-over-fiber link based on a commercial SFP+ module is demonstrated, allowing easy integration into existing PON solutions. Without active laser control good RF frequency stability and 225m wireless distance are achieved...

  3. DSP based coherent receiver for phase-modulated radio-over-fiber optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Tafur Monroy, Idelfonso; Peucheret, Christophe

    2008-01-01

    A novel DSP based coherent receiver for phase modulated radio-over-fiber optical links is reported. Using the proposed digital receiver, signal demodulation of 1.25 Gb/s ASK-modulated 10 GHz RF carrier is experimentally demonstrated.......A novel DSP based coherent receiver for phase modulated radio-over-fiber optical links is reported. Using the proposed digital receiver, signal demodulation of 1.25 Gb/s ASK-modulated 10 GHz RF carrier is experimentally demonstrated....

  4. An experimental study on digital predistortion for radio-over-fiber links

    Science.gov (United States)

    Vieira, Luis C.; Gomes, Nathan J.; Nkansah, Anthony

    2010-12-01

    Radio-over-fiber (RoF) has been proposed as an enabling technology for broadband networks, such as WiMAX and WiFi. Besides the inherent high bandwidth and reliability of RoF systems, they also allow the reduction of installation and maintenance cost of the remote antenna units (RAUs) and improvement in the coverage area of the base station/access point. However, the nonlinear distortion of the optical link, which stems mainly from the laser diode, may impose serious limitations on the system performance, especially when high PAPR, wideband signals are used. Thus, distortion compensation is a key issue in order to facilitate the application of the RoF technology for broadband networks. In this work, digital predistortion for directly modulated RoF links is experimentally investigated. A memory-polynomial- based predistorter model is identified from measurements of the baseband OFDM input-output signals and through the use of an indirect learning architecture. Then, a predistorted signal is generated and fed to the RoF link for comparing its output with that of the non-predistorted one. As a result of this compensation technique, an improvement of the static link linearity and the output constellation diagram has been found, with an EVM reduction of 1.73 %.

  5. Enabling uncompressed video transmission in double-sideband 60 GHz radio-over-fiber links

    DEFF Research Database (Denmark)

    Lebedev, Alexander; Vegas Olmos, Juan José; Iglesias Olmedo, Miguel

    2012-01-01

    We experimentally investigate the 60 GHz double-sideband radio-over-fiber link. We present the bit error rate performance of the system for HD video transmission in the access architecture and the phase noise measurements for metro-access scenarios.......We experimentally investigate the 60 GHz double-sideband radio-over-fiber link. We present the bit error rate performance of the system for HD video transmission in the access architecture and the phase noise measurements for metro-access scenarios....

  6. 15Gbit/s Duobinary Transmission Over a W-Band Radio-over-Fiber Link

    DEFF Research Database (Denmark)

    Rommel, Simon; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2016-01-01

    In this paper the transmission of a 15Gbit/s duobinary signal over a W-band hybrid photonic wireless link is demonstrated experimentally. The radio-over-fiber link consists of 10km SMF and a wireless distance of 50m, utilizing RF carriers at 83–87GHz. Transmission of a 15Gbit/s duobinary signal...

  7. 15Gbit/s Duobinary Transmission Over a W-Band Radio-over-Fiber Link

    DEFF Research Database (Denmark)

    Rommel, Simon; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2016-01-01

    In this paper the transmission of a 15Gbit/s duobinary signal over a W-band hybrid photonic wireless link is demonstrated experimentally. The radio-over-fiber link consists of 10km SMF and a wireless distance of 50m, utilizing RF carriers at 83–87GHz. Transmission of a 15Gbit/s duobinary signal i...... is achieved with a BER of 2.9×10-3, i.e. below the limit for a 7% overhead FEC.......In this paper the transmission of a 15Gbit/s duobinary signal over a W-band hybrid photonic wireless link is demonstrated experimentally. The radio-over-fiber link consists of 10km SMF and a wireless distance of 50m, utilizing RF carriers at 83–87GHz. Transmission of a 15Gbit/s duobinary signal...

  8. Performance Evaluation of Digital Coherent Receivers for Phase-Modulated Radio-Over-Fiber Links

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Zibar, Darko; Tafur Monroy, Idelfonso

    2011-01-01

    The performance of optical phase-modulated (PM) radio-over-fiber (RoF) links assisted with coherent detection and digital signal processing (PM-Coh) is analyzed and experimentally demonstrated for next-generation wireless-over-fiber systems. PM-Coh offers high linearity for transparent transport......-bandwidth electronics. Analytical assessment and simulations are used to determine the ultimate performance with respect to laser linewidth, modulation index, and receiver sensitivity. Then, two different scenarios are studied and experimentally demonstrated as an application of PM-Coh links: a high...

  9. Photonic downconversion for coherent phase-modulated radio-over-fiber links using free-running local oscillator

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Zibar, Darko; Schäffer, Christian G.

    2011-01-01

    A digital coherent receiver employing photonic downconversion is presented and experimentally demonstrated for phase-modulated radio-over-fiber optical links. Photonic downconversion adds additional advantages to optical phase modulated links by allowing demodulation of signals with RF carrier...... frequencies exceeding the bandwidth of electrical analog-to-digital converter. High spurious-free dynamic range is observed for RF carriers at 5GHz photonically downconverted to 1GHz....

  10. Multi-dimensional crest factor reduction and digital predistortion for multi-band radio-over-fiber links.

    Science.gov (United States)

    Chen, Hao; Li, Jianqiang; Yin, Chunjing; Xu, Kun; Dai, Yitang; Yin, Feifei

    2014-08-25

    A multi-dimensional crest factor reduction (MD-CFR) technique is proposed to improve the performance and efficiency of multi-band radio-over-fiber (RoF) links. Cooperating with multi-dimensional digital predistortion (MD-DPD), MD-CFR increases the performance of both directly-modulated and externally-modulated RoF links, in terms of error vector magnitude (EVM) and adjacent channel power ratio (ACPR). For directly-modulated RoF link, more than 5 dB output ACPR reduction is obtained, output EVMs are reduced from 11.83% and 12.47% to 7.51% and 7.26% for two bands respectively, while only a slight improvement to 11.58% and 10.78% is obtained solely using MD-DPD. Similar results are achieved in externally-modulated RoF link. Given a threshold in EVM or ACPR, the RF power transmit efficiency is also further enhanced.

  11. Cognitive digital receiver for burst mode phase modulated radio over fiber links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Tafur Monroy, Idelfonso

    2010-01-01

    A novel cognitive receiver for modulation format recognition with reconfigurable carrier recovery scheme is proposed and experimentally demonstrated for phase modulated radio-over-fibre links. Demodulation of burst-mode mixed modulation formats (PSK and QAM) is demonstrated after 40km of transmis......A novel cognitive receiver for modulation format recognition with reconfigurable carrier recovery scheme is proposed and experimentally demonstrated for phase modulated radio-over-fibre links. Demodulation of burst-mode mixed modulation formats (PSK and QAM) is demonstrated after 40km...

  12. On the capacity of radio-over-fiber links at the W-band

    DEFF Research Database (Denmark)

    Cavalcante, Lucas Costa Pereira; Rommel, Simon; Rodríguez Páez, Juan Sebastián

    2016-01-01

    provide a set of trade-off maps in terms of crucial resources on the design of W-band RoF links. The proposed framework offers a unified view for answering how fundamental spectrum resources can be optimally utilized, and how far we are from overcoming the challenge of offering seamless convergence...

  13. Bandpass sampling based digital coherent receiver with free-running local oscillator laser for phase-modulated radio-over-fiber links.

    Science.gov (United States)

    Cao, Minghua; Li, Jianqiang; Dai, Yitang; Yin, Feifei; Xu, Kun

    2014-11-03

    A bandpass sampling based digital coherent receiver is presented for phase modulated radio-over-fiber links with coherent detection. In the scheme, the bandpass sampling technique is introduced in RoF systems to overcome the high sampling rate requirement and front-end hardware dependency of conventional digtal coherent receivers. In particular, the selection rule of bandpass sampling rate was defined by taking into account the frequency offset induced by free-running optical local oscillator. Analytical assessment and simulations are used to determine the ultimate performance in terms of tolerances to ADC bit resolution and laser linewidth. Thereafter, a 40Mbps QPSK modulated data signal at 2.4GHz RF carrier frequency is experimentally demonstrated over the proposed 50.6-km radio-over-fiber link employing bandpass sampling.

  14. Experimental 2.5-Gb/s QPSK WDM phase-modulated radio-over-fiber link with digital demodulation by a K-means algorithm

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Caballero Jambrina, Antonio

    2010-01-01

    Highest reported bit rate of 2.5 Gb/s for optically phase modulated radio-over-fiber (RoF) link, employing digital coherent detection, is demonstrated. Demodulation of 3$,times,$ 2.5 Gb/s quadrature phase-shift keying modulated wavelength-division-multiplexed RoF channels is achieved after 79 km...... of transmission through deployed fiber. Error-free performance (bit-error rate corresponding to $10^{{-}4}$) is achieved using a digital coherent receiver in combination with a $K$-means algorithm for radio-frequency phase recovery....

  15. Performance Evaluation of Wavelet-Coded OFDM on a 4.9 Gbps W-Band Radio-over-Fiber Link

    DEFF Research Database (Denmark)

    Cavalcante, Lucas Costa Pereira; Rommel, Simon; Dinis, Rui

    2017-01-01

    Future generation mobile communications running on mm-wave frequencies will require great robustness against frequency selective channels. In this work we evaluate the transmission performance of 4.9 Gbps Wavelet-Coded OFDM signals on a 10 km fiber plus 58 m wireless Radio-over-Fiber link using...... a mm-wave radio frequency carrier. The results show that a 2×128 Wavelet-Coded OFDM system achieves a bit-error rate of 1e-4 with nearly 2.5 dB less signal-to-noise ratio than a convolutional coded OFDM system with equivalent spectral efficiency for 8 GHz-wide signals with 512 sub-carriers on a carrier...

  16. Evaluation of selective control information detection scheme in orthogonal frequency division multiplexing-based radio-over-fiber and visible light communication links

    Science.gov (United States)

    Dalarmelina, Carlos A.; Adegbite, Saheed A.; Pereira, Esequiel da V.; Nunes, Reginaldo B.; Rocha, Helder R. O.; Segatto, Marcelo E. V.; Silva, Jair A. L.

    2017-05-01

    Block-level detection is required to decode what may be classified as selective control information (SCI) such as control format indicator in 4G-long-term evolution systems. Using optical orthogonal frequency division multiplexing over radio-over-fiber (RoF) links, we report the experimental evaluation of an SCI detection scheme based on a time-domain correlation (TDC) technique in comparison with the conventional maximum likelihood (ML) approach. When compared with the ML method, it is shown that the TDC method improves detection performance over both 20 and 40 km of standard single mode fiber (SSMF) links. We also report a performance analysis of the TDC scheme in noisy visible light communication channel models after propagation through 40 km of SSMF. Experimental and simulation results confirm that the TDC method is attractive for practical orthogonal frequency division multiplexing-based RoF and fiber-wireless systems. Unlike the ML method, another key benefit of the TDC is that it requires no channel estimation.

  17. Reconfigurable digital receiver for 8PSK subcarrier multiplexed and 16QAM single carrier phase‐modulated radio over fiber links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2011-01-01

    A reconfigurable digital receiver based on the k‐means algorithm is proposed for phase‐modulated subcarrier multiplexed (SCM) and quadrature amplitude‐modulated single carrier, phase‐modulated radio‐over‐fiber links. We report successful demodulation after 40 km single mode fiber transmission...

  18. Optical phase-modulated radio-over-fiber links with k-means algorithm for digital demodulation of 8PSK subcarrier multiplexed signals

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2010-01-01

    A k-means algorithm for phase recovery of three, 50 Mbaud, 8PSK subcarrier multiplexed signals at 5 GHz for optical phase-modulated radio-over-fiber is proposed and experimentally demonstrated after 40 km of single mode fiber transmission...

  19. Reconfigurable Radio-Over-Fiber Networks [Invited

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2015-01-01

    This paper discusses reconfigurable Radio-over-Fiber networks, including activities in coherent remote access units, silicon photonics for microwave photonics and optical switching.......This paper discusses reconfigurable Radio-over-Fiber networks, including activities in coherent remote access units, silicon photonics for microwave photonics and optical switching....

  20. Reconfigurable Radio-Over-Fiber Networks

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2015-01-01

    This paper discusses reconfigurable Radio-over-Fiber networks, including activities in coherent remote access units, silicon photonics for microwave photonics and optical switching.......This paper discusses reconfigurable Radio-over-Fiber networks, including activities in coherent remote access units, silicon photonics for microwave photonics and optical switching....

  1. Gigabit radio-over-fiber link for converged baseband and millimeter-wave band signal transmission using cascaded injection-locked Fabry-Pérot laser diodes.

    Science.gov (United States)

    Hong, Moon-Ki; Won, Yong-Yuk; Han, Sang-Kook

    2009-05-11

    A novel scheme, for both baseband and millimeter-wave band gigabit data transmission in radio-over-fiber system, is proposed and experimentally demonstrated by using cascaded injection-locked Fabry- Pérot laser diodes. It was able to improve suppression ratio of carrier suppressed signal using the cascaded injection-locking. The suppression ratio improvement of the optical carrier suppressed signal of 20 dB was verified. Applying this mechanism, 60-GHz millimeter-wave carrier of enhanced signal quality could be accomplished. Its peak power and phase noise were obtained as -40 dBm and -103.5 dBm/Hz respectively, which was suitable for 60-GHz data transmission. In addition, a successful bidirectional transmission of 1.25-Gbps wired and wireless data was achieved by adopting remodulation technique using a gain-saturated reflective semiconductor optical amplifier for uplink.

  2. Upgradable radio-over-fiber transport system

    Science.gov (United States)

    Chang, Ching-Hung; Tu, Liang-Shuo; Huang, Yi-Syuan; Li, Chung-Yi

    2017-10-01

    An upgradable radio-over-fiber (RoF) transport system is proposed based on a vertical-cavity surface-emitting laser (VCSEL)-composed wavelength selector. The passband window of the wavelength selector can be electrically adjusted to select a specific lightwave from multiple injected optical carriers and attenuate the others. By adding the VCSEL-composed wavelength selector installed inside each base station (BS), the proposed transport system can remain as the original tree topology, but its overall network capacity can be flexibly extended (reduced) by adding (removing) an additional optical carrier into (out of) the optical network. Each BS can dynamically receive data from one of the multiple injected optical carriers. This method is useful because the bandwidth requirement of each BS, which is serviced by an RoF transport system, may significantly change with the visitor flow rate. Experimental results prove that the BSs in the proposed upgradable RoF transport system can be reallocated to multiple logical RoF links and can be dynamically switched to receive data from any one of the logical RoF signals without modifying the original network structure. The transmission performances of these optical carriers are ensured by low bit error rate, clear eye, and optical/electrical spectra diagrams.

  3. Next generation wireless communications using radio over fiber

    CERN Document Server

    Gomes, Nathan J; Gameiro, Atilio

    2012-01-01

    Taking a coherent and logical approach, this book describes the potential use of co-ordinated multipoint systems supported by radio over fiber. It covers an impressive breadth of topics, ranging from components, subsystem and system architecture, to network management and business perspectives. The authors show the importance of radio over fiber in eliminating or mitigating against the current, perceived barriers to the use of co-ordinated multipoint, and the drivers for standardisation activities in future mobile/wireless systems over the next few years. The book brings together the

  4. Architectures for radio over fiber transmission of high-quality video and data signals

    DEFF Research Database (Denmark)

    Lebedev, Alexander

    In this Ph.D. project, design and performance evaluation of mm-wave radio over fiber links for diverse applications including video transmission are conducted. Major objective of this Thesis is to study performance of video and data signals transmitted in radio over fiber (RoF) setups...... frequency (RF) power fading in a simple intensity modulation-direct detection mm-wave RoF link through introduction of a degree of frequency tunability at the RoF transmitter. We study advanced RoF infrastructures to better suit video transmission. To enable efficient dynamic multicast/broadcast of video...... to designated BSs is evaluated for diverse lightwave generation and data modulation techniques. Mm-wave RoF links employing various lightwave generation techniques are experimentally demonstrated for diversified fiber infractructure including standard single mode fiber, multimode fiber and dispersion shifted...

  5. Radio-over-Fiber Transmission Using Vortex Modes

    DEFF Research Database (Denmark)

    Tatarczak, Anna; Lu, Xiaofeng; Rommel, Simon

    2015-01-01

    This paper demonstrates experimentally the distribution of radio-over-fiber (RoF) signals using orbital angular momentum (OAM) of light over standard OM4 multimode fiber (MMF) at 850 nm wavelength. Five independent OAM modes are used to convey RoF signals in the microwave regime showing robust...

  6. Performance improvement on a MIMO radio-over-fiber system by probabilistic shaping

    Science.gov (United States)

    Kong, Miao; Yu, Jianjun

    2018-01-01

    As we know, probabilistic shaping (PS), as a typical one of modulation format optimization technologies, becomes a promising technology and attracts more and more attention, because of its higher transmission capacity and lower computation complexity. In this paper, we experimentally demonstrated a reliable 8 Gbaud-rate delivery of polarization multiplexed PS 16-QAM single carrier signal in a MIMO radio-over-fiber system with 20-km SMF-28 wire link and 2.5-m wireless link at 60 GHz. The BER performance of PS 16-QAM signals at different baud rate was also evaluated. What is more, PS 16-QAM was also experimentally compared with uniform 16-QAM, and it can be concluded that PS 16-QAM brings a better compromise between effectiveness and reliability performance and a higher capacity than uniform 16-QAM for the radio-over-fiber system.

  7. Digital coherent detection of multi-gigabit 40 GHz carrier frequency radio-over-fiber signals using photonic downconversion

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Zibar, Darko; Tafur Monroy, Idelfonso

    Detection of high speed radio signals is a challenge for next generation radio-over-fiber links, requiring high bandwidth and linearity in the receiver. By using photonic downconversion in a coherent receiver, it is possible to detect signals exceeding the electrical bandwidth of the receiver...

  8. Bidirectional hybrid CATV/radio-over-fiber WDM transport system.

    Science.gov (United States)

    Lu, Hai-Han; Peng, Hsiang-Chun; Tsai, Wen-Shing; Lin, Chun-Cheng; Tzeng, Shah-Jye; Lin, Yi-Zsai

    2010-02-01

    A bidirectional hybrid cable antenna television (CATV)/radio-over-fiber (ROF) wavelength-division-multiplexing (WDM) transport system using injection locking technique to suppress the rf power degradation, tunable optical bandpass filter to generate optical single-sideband format for the CATV signal or only one optical sideband format for the ROF one, and photonic crystal fiber to reduce the net dispersion is proposed and demonstrated. Impressive performances of the carrier-to-noise ratio, the composite second-order, the composite triple beat, and the bit error rate were obtained in our proposed systems.

  9. On Radio over Fiber for Heterogeneous Wireless Networks

    DEFF Research Database (Denmark)

    Riaz, M. Tahir; Nielsen, Rasmus Hjorth; Pedersen, Jens Myrup

    2009-01-01

    The paper provides an overview of the radio over fiber (RoF) technology and its potential use in heterogeneous wireless networks. Wireless communications have seen a huge growth in the last decade. It has been estimated that five in every six people in the entire world will have a mobile phone...... provisioning - FUTON) based on RoF technology has been introduced. The project adopts centralized processing of radio signals for number of wireless base stations can enhance the network performance in terms of bandwidth, and QoS parameters. The simplified remote access units (RAU) are expected to not only...

  10. Linearization Technologies for Broadband Radio-Over-Fiber Transmission Systems

    Directory of Open Access Journals (Sweden)

    Xiupu Zhang

    2014-11-01

    Full Text Available Linearization technologies that can be used for linearizing RoF transmission are reviewed. Three main linearization methods, i.e. electrical analog linearization, optical linearization, and electrical digital linearization are presented and compared. Analog linearization can be achieved using analog predistortion circuits, and can be used for suppression of odd order nonlinear distortion components, such as third and fifth order. Optical linearization includes mixed-polarization, dual-wavelength, optical channelization and the others, implemented in optical domain, to suppress both even and odd order nonlinear distortion components, such as second and third order. Digital predistortion has been a widely used linearization method for RF power amplifiers. However, digital linearization that requires analog to digital converter is severely limited to hundreds of MHz bandwidth. Instead, analog and optical linearization provide broadband linearization with up to tens of GHz. Therefore, for broadband radio over fiber transmission that can be used for future broadband cloud radio access networks, analog and optical linearization are more appropriate than digital linearization. Generally speaking, both analog and optical linearization are able to improve spur-free dynamic range greater than 10 dB over tens of GHz. In order for current digital linearization to be used for broadband radio over fiber transmission, the reduced linearization complexity and increased linearization bandwidth are required. Moreover, some digital linearization methods in which the complexity can be reduced, such as Hammerstein type, may be more promising and require further investigation.

  11. Radio over fiber for wireless communications from fundamentals to advanced topics

    CERN Document Server

    Fernando, Xavier N

    2014-01-01

    A comprehensive evaluation of Fi-Wi,  enabling readers to design links using channel estimation and equalization algorithms  This book provides a detailed study of radio over fiber (ROF) based wireless communication systems, otherwise called fiber wireless (Fi-Wi) systems. This is an emerging hot topic where the abundant bandwidth of optical fiber is directly combined with the flexibility and mobility of wireless networks to provide broadband connectivity.  Its application is increasing because of the growing demand for broadband wireless services. In such a system the transmission of the ra

  12. Quality Analysis in Phase Modulated Radio over Fiber in WDM/DWDM Network

    Science.gov (United States)

    Sahoo, S.; Kiran, K. V.; Kumar, V.; Yadav, D.; Barpanda, N. K.; Das, Santos Kumar

    2017-05-01

    There has been increasing demand for connection setup with a higher quality of service (QoS) in WDM/DWDM networks, especially in fields like radio over fiber, where phase modulation affects the link quality. Hence to meet guaranteed QoS in a phase modulated link, the effects of phase modulation on link quality are very much needed. The link quality is termed as quality factor (Q-factor). The primary objective is to use effectively the connections available to optimize the computed number of connections and reduce the blocked connections but at the same time guaranteeing QoS as per client's need. The analysis has been done by taking care of routing and wavelength assignment (RWA) techniques. The performance analysis is presented in terms of blocking probability.

  13. Practical demonstration of spectrally efficient FDM millimeter-wave radio over fiber systems for 5G cellular networking

    Science.gov (United States)

    Mikroulis, Spiros; Xu, Tongyang; Darwazeh, Izzat

    2016-02-01

    This work reports the first demonstration of spectrally efficient frequency division multiplexed (SEFDM) signal transmission based on mm-wave radio over fiber (RoF) technology. Such systems aim to satisfy the beyond 4G (5G) demands of low cost, low energy, millimeter-wave carrier frequencies and high spectral efficiency. The proposed radio over fiber topology, using passive optical network (PON) infrastructure and low-cost multimode fiber (MMF), is analyzed and a proof-of-concept SEFDM radio over 250m OM-1 MMF transmission with a 3m 60GHz wireless link is successfully demonstrated. Different systems are demonstrated, at raw data rates up to 3.7 Gb/s, showing SEFDM spectrum saving up to 40% relative to OFDM.

  14. Radio-over-fiber linearization with optimized genetic algorithm CPWL model.

    Science.gov (United States)

    Mateo, Carlos; Carro, Pedro L; García-Dúcar, Paloma; De Mingo, Jesús; Salinas, Íñigo

    2017-02-20

    This article proposes an optimized version of a canonical piece-wise-linear (CPWL) digital predistorter in order to enhance the linearity of a radio-over-fiber (RoF) LTE mobile fronthaul. In this work, we propose a threshold allocation optimization process carried out by a genetic algorithm (GA) in order to optimize the CPWL model (GA-CPWL). Firstly, experiments show how the CPWL model outperforms the classical memory polynomial DPD in an intensity modulation/direct detection (IM/DD) RoF link. Then, the GA-CPWL predistorter is compared with the CPWL model in several scenarios, in order to verify that the proposed DPD offers better performance in different optical transmission conditions. Experimental results reveal that with a proper threshold allocation, the GA-CPWL predistorter offers very promising outcomes.

  15. Compact Wireless Access Nodes for WDM Bidirectional Radio-over-Fiber System Based on RSOA

    DEFF Research Database (Denmark)

    Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

    2009-01-01

    We demonstrate a RSOA based WDM radio-over-fiber, bidirectional system for wireless access networks. The multi-functionalities of a RSOA, such as colorless operation, re-modulation and envelope detection, make wireless access nodes more compact.......We demonstrate a RSOA based WDM radio-over-fiber, bidirectional system for wireless access networks. The multi-functionalities of a RSOA, such as colorless operation, re-modulation and envelope detection, make wireless access nodes more compact....

  16. 64-GHz millimeter-wave photonic generation with a feasible radio over fiber system

    Science.gov (United States)

    Al-Dabbagh, Rasha K.; Al-Raweshidy, Hamed S.

    2017-02-01

    A full-duplex radio over fiber (RoF) link with the generation of a 64-GHz millimeter wave (mm-wave) is investigated. This system is proposed as a solution to cope with the demands of a multi-Gb/s data transmission in the fifth generation (5G) and beyond for small cell networks. Cost reduction and performance improvement are achieved by simplifying the mm-wave generation method with an RoF technique. High-frequency radio signals are considered challenging in the electrical generation domain; therefore, our photonic generation method is introduced and examined. RoF design is proposed for mm-wave generation using both phase modulation and the effect of stimulated Brillouin scattering in the optical fiber for the first time. RoF system with transmission rates of 5 Gb/s is successfully achieved. In our scheme, one laser source is utilized and a fiber Bragg grating is used for wavelength reuse for the uplink connection. Stable mm-wave RoF link is successfully achieved in up to a 100-km fiber link length with high quality carrier. Simulation results show a reduction in fiber nonlinearity effects and the mm-wave signal has low noise equal to -75 dBm. This study ensures a practical mm-wave RoF link, and it could be appropriate for small cell 5G networks by reducing the installation cost.

  17. Performance Evaluation for DFB and VCSEL-based 60 GHz Radio-over-Fiber System

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Lebedev, Alexander; Vegas Olmos, Juan José

    2013-01-01

    In this paper, we report on a detailed analysis and performance comparison work between 60 GHz radio-over-fiber systems based on a DFB laser and a C-band VCSEL. Coherent photonic up-conversion method is applied for the 60 GHz millimeter-wave signal generation. The generated signals are evaluated...

  18. Reconfigurable remote access unit for W-band Radio-over-Fiber transmission

    DEFF Research Database (Denmark)

    Chorchos, Łukasz; Rommel, Simon; Turkiewicz, Jarosław P.

    2016-01-01

    There is a growing demand for cost-effective radio over fibre transmission techniques. In this paper, we propose and realize the reconfigurable remote access unit for radio-over-fiber transmission. The reconfigurable unit is build from the tunable filter and laser as well as remote controller. Su...

  19. Triple-Play and 60-GHz Radio-over-Fiber Techniques for Next-Generation Optical Access Networks

    DEFF Research Database (Denmark)

    Llorente, R.; Walker, S.; Tafur Monroy, Idelfonso

    2011-01-01

    Radio-over-fiber techniques apply to fiber-to-thehome distributions to reach the customer premises with the services to be received with full-standard low-cost equipment. Bi-directional coarse wavelength division multiplexing (CWDM) radio-over-fiber transmission of triple-format full-standard ort...

  20. Mitigation of signal fading in radio over fiber transmission using fiber nonlinearity.

    Science.gov (United States)

    Maeda, Joji; Kusama, Kazutoyo; Fukuchi, Yutaka

    2009-03-16

    Radio over fiber systems in a microwave/millimeter wave band experience a severe signal fading due to fiber dispersion. However, parametric amplification in transmission fibers, known as modulation instability, can compensate for the signal fading. In this paper, we experimentally demonstrate radio over fiber transmission of 111.689 Mbps BPSK signal with a carrier frequency of 10.804 GHz, and measure bit error rates varying the optical transmission power. For the fiber launched power of 0 dBm, we observe a power penalty of 5.8 dB in the transmission over a 25 km fiber, though by increasing the fiber launched power up to +10 dBm, we successfully reduce the power penalty by 1.1 dB. (c) 2009 Optical Society of America

  1. Effective Design for Optical CDMA Based on Radio over Fiber (RoF Technique

    Directory of Open Access Journals (Sweden)

    Rashidi C. B. M.

    2017-01-01

    Full Text Available In this paper, the performance of OCDMA coding systems utilizing the radio over fiber (RoF technique is presented. It has been done by means of conventional OptiSystem simulation tools, where the propagation of radio signals up to 50 km using standard single mode fiber (SMF was investigated. The analysis was made based on the performance of eye diagram, bit rate, bit error rate and optical received power.

  2. Coverage Range and Cost Comparison of Remote Antenna Unit Designs for Inbuilding Radio over Fiber Technology

    Directory of Open Access Journals (Sweden)

    Razali Ngah

    2013-09-01

    Full Text Available Future communication needs to be ubiquitous, broadband, convergent, and seamless. Radio over fiber (RoF technology is one of the most important enabler in access network for the technologies. Adoption of RoF faces bottleneck in optoelectronics, that they are still expensive, high power consumption, and limited in bandwidth. To solve the problem, transceiver in remote antenna unit (RAU is developed, i.e. electroabsorption transceiver (EAT and asymmetric FabryPerot modulator (AFPM. This paper compares their coverage range and cost in providing WCDMA and WLAN services. Needed gain of RF amplifier for supporting picocell is also discussed.

  3. Study of converged 60 GHz radio over fiber with WDM-PON access networks

    OpenAIRE

    Shao, Tong

    2012-01-01

    Recently, convergence of 60 GHz radio over fiber (RoF) technique with wavelength division multiplexing (WDM) passive optical networks (PON) has raised great interests because it provides the possibility for simultaneous broadband 60 GHz signal generation and multi-gigabit per second wireline transmission. The objective of the thesis is to study the solutions for converged 60 GHz RoF and WDM-PON technique.In this thesis, we have made the following achievements for RoF technology and the integr...

  4. Radio-over-fiber technology and devices for 5G: an overview

    Science.gov (United States)

    Iezekiel, Stavros

    2016-02-01

    Radio-over-fiber has received renewed impetus due to various worldwide research initiatives in 5G. Here we will highlight recent developments at the device and integration level that are driving development of systems at various mmwave and sub-THz carriers, such as 30 GHz, 60 GHz and 120 GHz. Various device and circuit technologies will be reviewed in the framework of recent European projects. In addition, we will examine the outlook for monolithic and hybrid integration as a means of meeting size and power consumption requirements in picocell and femtocell applications.

  5. Reconfigurable radio-over-fiber system based on optical switch and tunable filter

    Science.gov (United States)

    Li, Xiao; Yin, Rui; Ji, Wei; Sun, Kai; Zhang, Shicheng

    2017-09-01

    As the best candidate for wireless-access networks, radio-over-fiber (RoF) technology can carry a variety of business. It is necessary to provide differentiated services for different users, so the network needs to produce signals with different modulation formats and different frequencies. A reconfigurable RoF system based on a switch and tunable optical filter that can realize modulation format conversion and multiple frequency signal switching functions is designed. It has a good performance in terms of bit error rate and an eye diagram. The design can help to use radio frequency resources efficiently and make dynamic bandwidth resources controllable.

  6. A Review on Radio-Over-Fiber Technology-Based Integrated (Optical/Wireless) Networks

    Science.gov (United States)

    Rajpal, Shivika; Goyal, Rakesh

    2017-06-01

    In the present paper, radio-over-fiber (RoF) technology has been proposed, which is the integration of the optical and radio networks. With a high transmission capacity, comparatively low cost and low attenuation, optical fiber provides an ideal solution for accomplishing the interconnections. In addition, a radio system enables the significant mobility, flexibility and easy access. Therefore, the system integration can meet the increasing demands of subscribers for voice, data and multimedia services that require the access network to support high data rates at any time and any place inexpensively. RoF has the potentiality to the backbone of the wireless access network and it has gained significant momentum in the last decade as a potential last-mile access scheme. This paper gives the comprehensive review of RoF technology used in the communication system. Concept, applications, advantages and limitations of RoF technology are also discussed in this paper.

  7. Performance Enhancement of Optical CDMA by Differential-Phase Method for Radio-over-Fiber Transmissions

    Directory of Open Access Journals (Sweden)

    Hsu-Chih Cheng

    2013-01-01

    Full Text Available The study proposes the differential-phase optical code-division multiple-access (OCDMA network for radio-over-fiber (RoF transmissions, and the characteristics are numerically analyzed. The network coder/decoders (codecs are structured on the basis of arrayed-waveguide-grating (AWG routers with complementary Walsh-Hadamard (CWH signature codes. In the proposed system, the network requires only two AWG routers to accomplish spectral encoding of radio base station (RBS and decoding of control station for the complementary keying, thus resulting in a simpler and low cost system. Performance analyses are evaluated with the dominant noise of phase-induced intensity noise (PIIN in spectral code OCDMA network. By the proposed AWG-based OCDMA with the differential-phase scheme, it is possible to establish interference-free and low crosstalk beat noise RoF systems.

  8. Direct CATV modulation and phase remodulated radio-over-fiber transport system.

    Science.gov (United States)

    Lin, Wen-Yi; Chang, Ching-Hung; Peng, Peng-Chun; Lu, Hai-Han; Huang, Ching-Hsiu

    2010-05-10

    A novel transport system, with directly modulating community antenna television (CATV) signal downstream and phase-remodulating radio-over-fiber (ROF) signal upstream, is proposed and experimentally demonstrated. By modulating multi-carriers CATV signal in amplitude domain and ROF signal in phase domain, a single optical wavelength is able to serve these two applications simultaneous. To be the first system of communicating CATV signal downstream and phase remodulating radio signal upstream, the performances of transmitting CATV and radio signals over 20 km single-mode fiber (SMF) were experimentally verified. Good performances of carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple beat (CTB) were obtained for CATV applications as well as high extinction ration (ER) and low bit error rate (BER) values were measured for ROF transmission. (c) 2010 Optical Society of America.

  9. Simplified radio-over-fiber transport systems with a low-cost multiband light source.

    Science.gov (United States)

    Chang, Ching-Hung; Peng, Peng-Chun; Lu, Hai-Han; Shih, Chine-Liang; Chen, Hwan-Wen

    2010-12-01

    In this Letter, low-cost radio-over-fiber (ROF) transport systems are proposed and experimentally demonstrated. By utilizing a laser diode (LD) and a local oscillator (LO) to generate coherent multiband optical carriers, as well as a self-composed wavelength selector to separate every two carriers for different ROF transport systems, no any other dedicated LD or electrical frequency upconverting circuit/process is needed in the central station (CS). Compared with current ROF systems, the required numbers of LDs, LOs, and mixers in a CS are significantly reduced. Reducing the number of components not only can simplify the network structure but can also reduce the volume and complexity of the relative logistics. To demonstrate the practice of the proposed ROF transport systems, clear eye diagrams and error-free transmission performance are experimentally presented.

  10. 2 × 2 MIMO radio-over-fiber system at 60 GHz employing frequency domain equalization.

    Science.gov (United States)

    Lin, Chun-Ting; Ng'oma, Anthony; Lee, Wei-Yuan; Wei, Chia-Chien; Wang, Chih-Yun; Lu, Tsung-Hung; Chen, Jyehong; Jiang, Wen-Jr; Ho, Chun-Hung

    2012-01-02

    This work experimentally demonstrates the efficacy of the 2 × 2 multiple-input multiple-output (MIMO) technique for capacity improvement of a 60-GHz radio-over-fiber (RoF) system employing single-carrier modulation format. We employ frequency domain equalization (FDE) to estimate the channel response, including frequency response of the 60 GHz RoF system and the MIMO wireless channel. Using FDE and MIMO techniques, we experimentally demonstrate the doubling the of wireless data capacity of a 60 GHz RoF system to 27.15 Gb/s using 16-QAM modulation format, with transmission over 25 km of standard single-mode fiber and 3 m wireless distance.

  11. Millimeter-wave and Terahertz Reconfigurable Radio-over-Fiber Systems

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José

    on photonic technologies enable to generate, transport and radiate in a straight forward manner microwave and millimeter wave signals. Although electronic technologies are able to sustain an increase in frequency from a technology point of view, with current developments hitting the Terahertz regime...... when deploying fiber is not an option. Radio-over-Fiber (RoF) technologies have evolved from a blue sky academic topic in the 90s to a main driver within the current quest for the 5th generation mobile systems (5G). A twist in RoF technologies is that it has found along the way niches in areas non...... purely related to communication technologies (ICT) applications: distribution of highly pure clock signals for radio telescopes, photonic-based coherent radar and fiber optic sensing. It is however in the communication arena where RoF seems to be able to provide a technological edge; RoF techniques based...

  12. Double-locked semiconductor laser for radio-over-fiber uplink transmission.

    Science.gov (United States)

    Cui, Cuicui; Fu, Xuelei; Chan, Sze-Chun

    2009-12-15

    The nonlinear dynamics of an optically injected semiconductor laser are explored for radio-over-fiber uplink transmission. Under optical injection locking, the laser at the base station is operated in the period-one oscillation state, where its intensity oscillates at a tunable microwave frequency. When the oscillation is tuned to the subcarrier frequency, it is further locked by the uplink microwave signal. By simply using an ordinary 2.5-Gbps-grade semiconductor laser, uplink transmission of the phase-shift keying (PSK) signal at a subcarrier of 16 GHz with bit-error rate of less than 10(-11) is demonstrated experimentally. Microwave PSK to optical PSK is achieved at the double-locked laser, which allows all-optical demodulation without any high-speed microwave electronics.

  13. Performance analysis for IEEE 802.11 distributed coordination function in radio-over-fiber-based distributed antenna systems.

    Science.gov (United States)

    Fan, Yuting; Li, Jianqiang; Xu, Kun; Chen, Hao; Lu, Xun; Dai, Yitang; Yin, Feifei; Ji, Yuefeng; Lin, Jintong

    2013-09-09

    In this paper, we analyze the performance of IEEE 802.11 distributed coordination function in simulcast radio-over-fiber-based distributed antenna systems (RoF-DASs) where multiple remote antenna units (RAUs) are connected to one wireless local-area network (WLAN) access point (AP) with different-length fiber links. We also present an analytical model to evaluate the throughput of the systems in the presence of both the inter-RAU hidden-node problem and fiber-length difference effect. In the model, the unequal delay induced by different fiber length is involved both in the backoff stage and in the calculation of Ts and Tc, which are the period of time when the channel is sensed busy due to a successful transmission or a collision. The throughput performances of WLAN-RoF-DAS in both basic access and request to send/clear to send (RTS/CTS) exchange modes are evaluated with the help of the derived model.

  14. Directly-Modulated VCSELs for 2x2 MIMO-OFDM Radio over Fiber in WDM-PON

    DEFF Research Database (Denmark)

    Binti Othman, Maisara; Deng, Lei; Pang, Xiaodan

    2011-01-01

    We demonstrate directly- modulated VCSELs supporting 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20-km WDM-PON. Error-free signal demodulation of 64-subcarrier 4-QAM signals modulated at 198.5-Mb/s is achieved after fiber and 2-m indoor wireless transmission.......We demonstrate directly- modulated VCSELs supporting 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20-km WDM-PON. Error-free signal demodulation of 64-subcarrier 4-QAM signals modulated at 198.5-Mb/s is achieved after fiber and 2-m indoor wireless transmission....

  15. Multi-band radio over fiber system with all-optical halfwave rectification, transmission and frequency down-conversion

    DEFF Research Database (Denmark)

    Prince, Kamau; Tafur Monroy, Idelfonso

    2011-01-01

    We introduce a novel application of all-optical half-wave rectification in the transportation and delivery of multi-frequency radio-over fiber signals. System evaluation was performed of transmission over various optical fiber types and all-optical envelope detection was implemented to achieve...

  16. Tunable microwave photonic duplexer for full-duplex radio-over-fiber access.

    Science.gov (United States)

    Li, Peixuan; Pan, Wei; Zou, Xihua; Yan, Lianshan; Luo, Bin; Lu, Bing

    2017-02-20

    A tunable microwave photonic duplexer (MPD) for full-duplex radio-over-fiber access is proposed and experimentally demonstrated. The proposed MPD is implemented by two single-bandpass microwave photonic filters (MPFs) to separate the transmit (Tx) and receive (Rx) channels. More specifically, a broadband optical source (BOS) is spectrally sliced by a differential-group-delay interferometer (DGDI) and a Mach-Zehnder interferometer (MZI) to form two tunable single-bandpass MPFs with different central frequencies. The two MPFs are used for the Tx and Rx channels, respectively. By adjusting the free spectral ranges (FSRs) of the DGDI and MZI, the central frequencies of the Tx and Rx channels can be tuned independently in a wide frequency range. In the experiments, tunable ranges from 0 to 6.1 GHz for the Tx channel and from 0 to 17 GHz for the Rx channel are achieved. Meanwhile, a high isolation up to 44 dB between the Tx and Rx channels is also obtained. Based on the proposed MPD, the duplex transmission of a 10-MBaud 16-quadrature-amplitude-modulation (QAM) signal at 2.45 GHz and 2.82 GHz is demonstrated.

  17. Heterogeneous radio-over-fiber passive access network architecture to mitigate Rayleigh backscattering interferometric beat noise.

    Science.gov (United States)

    Yeh, C H; Chow, C W

    2011-03-28

    We propose and experimentally demonstrate a hybrid radio-over-fiber (ROF) wavelength division multiplexed and time division multiplexed passive optical network (WDM-TDM PON) architecture to mitigate Rayleigh backscattering (RB) interferometric beat noises. Here, only a single wavelength is needed at the central office (CO) to generate the downstream baseband data for optical wired application and optical millimeter-wave (mm-wave) signal for wireless application. The upstream signal is produced by remodulating the downstream signal. No optical filter is required at the optical network unit/remote antenna unit (ONU/RAU) to separate the optical wired and optical mm-wave signals. In the proposed network, 10 Gb/s differential phase shift keying (DPSK) signal is used for the downstream optical wired application and 2.5 Gb/s on-off keying (OOK) signal on 20 GHz carrier is used for the optical mm-wave signal. In each ONU, a reflective optical semiconductor amplifier (RSOA) is used to remodulate and produce a 2.5 Gb/s OOK format for upstream traffic. As the back-refection produced by the downstream DPSK signal and the upstream OOK signal is traveling in different fiber path, RB noise at the CO can be completely mitigated.

  18. Blind post processed nonlinearity mitigation in multiband OFDM radio over fiber optical transmission

    Science.gov (United States)

    Park, Hyoung-Joon; Jung, Sun-Young; Han, Sang-Kook

    2016-02-01

    We propose a blind adaptive post-processing method to reduce nonlinear distortion in multiband radio over fiber (RoF) transmission. Mitigating nonlinear distortion has been a critical challenge to enhance signal quality in RoF system due to analog optical transmission. To keep up with explosive increase in number of mobiles and their data capacity demands, remote antenna unit (RAU) has to be widely and densely distributed with RoF system. Consequently, RAU should be simple and compensation should be fully processed in central office (CO). In optical uplink transmission of RoF system, post-processing of distortion mitigation will be effective. In this paper, we propose post compensation structure constructed by means of Hammerstein equalizer without inserting preamble. Specifically, Hammerstein equalizer, which is separated into linear and nonlinear parts, was used to compensate both linear and nonlinear distortion of RoF system. The filter coefficients were updated adaptively by using LMS algorithm to adjust variable channel environments. In our experiment, multiband OFDM signal, which is LTE standard according to 3GPP, was optically transmitted through RoF channel. Experimental demonstration for the improvement of EVM performance with proposed post-processing was verified.

  19. Chaotic communication in radio-over-fiber transmission based on optoelectronic feedback semiconductor lasers.

    Science.gov (United States)

    Lin, Fan-Yi; Tsai, Meng-Chiao

    2007-01-22

    Performance of chaotic communication in radio-over-fiber (ROF) transmission based on optoelectronic feedback semiconductor lasers is studied numerically. The chaotic carrier is generated by optoelectronic feedback semiconductor lasers, where chaotic communication is realized by synchronizing a receiver laser with a transmitter laser. Transmission quality of different message encoding schemes, including additive chaos modulation (ACM) and on-off shift keying (OOSK), are investigated and compared. In this study, the dispersion and nonlinearity effects in the fiber transmission module and the amplified spontaneous emission noise from the optical amplifiers are considered. In the wireless channel, effects of additive white Gaussian noise, multipath, and path loss are included. To quantitatively study the performance of this chaotic communication system in the ROF transmission, bit-error-rates (BER) of different transmission lengths, message bit-rates, and signal-to-noise ratios are studied. The optimal launched power and message strength that minimize the BER while assuring effective communication security are discussed. While the ACM scheme is shown to perform better in a fiber only configuration, the OOSK scheme shows better immunity to the random effects and waveform distortions presented in the wireless channel.

  20. Next Generation Radio over Fiber Network Management for a Distributed Antenna System

    DEFF Research Database (Denmark)

    Santiago, Carlos; Gangopadhyay, Bodhisattwa; arsenio, Artur

    2009-01-01

    Dette dokument beskriver funktioner og procedurer i futon Radio Over Fiber Manager til at operere med det øvre (net) og nederste (fysiske) lag, der anvendes til transport af trådløse signaler mellem en central enhed (CU) og Remote Antenna Units. Også, det giver nogle mekanismer og procedurer, der...... skal anvendes i tilfælde af fejl, samtidig med at end-to-end service problemløsning og service kvalitetsstyring af Futon Middleware. En oversigt over aktuelle ROF Management-løsninger er i første omgang præsenteres. Det papir, så på nogle af de udfordringer, der i [1], nemlig specifikationen af Radio......-over-Fibre (ROF) leder virksomheden funktioner, der kontrollerer futon optisk infrastruktur definition af interoperabilitet med futon Middleware og Radio Resource Management, og definitionen af ROF Management funktioner, som er tæt korreleret og integreret med radio-og optiske interface, fysiske lag algoritmer på...

  1. A flexible millimeter-wave radio-over-fiber system for various transmission bit rate

    Science.gov (United States)

    Yang, Tao; Gao, Mingyi; Qian, Jiaqin; Zhang, Junfeng; Chen, Wei

    2017-11-01

    In this paper, we propose a flexible scheme to generate millimeter-waves (MMWs) for millimeter-wave radio-over-fiber (MMW-RoF) system. The proposed scheme has two configurations to adapt to various transmission bit rate by slightly rearranging the allocation of the system. The main structure of the system is cascaded LiNbO3 Mach-Zehnder modulators (LiNbO3-MZMs). The first configuration is cost effective method, where we utilize a wavelength division multiplexing de-multiplexer (WDM Demux) and an optical splitter (OS) to generate two unmodulated optical signals and a modulated optical signal. Each unmodulated optical signal and the modulated signal will form an optical single sideband (OSSB) modulation and therefore we simultaneously achieve a Q-band (45 GHz) and a V-band (60 GHz) MMWs in the receiver. The bit-error-ratio (BER) curves show that the power penalties of 45 GHz and 60 GHz are 0.6 dB and 1.1 dB at a BER of 1 × 10-9 with 2.5 Gb/s transmission data rate and 50 km fiber transmission distances. The second configuration can accommodate high bit rate, where few optical devices is rearranged to only generate a 60 GHz MMW with 40 Gb/s 4 quadrature amplitude modulation orthogonal frequency division multiplexing (4-QAM OFDM) signals. The power penalty is 1.1 dB at a BER of 1 × 10-9 with 50 km fiber transmission distances. Therefore, the proposed scheme can flexibly generate either two Q&V-band MMWs (45 GHz and 60 GHz) for the applications of the low data-rate transmission systems or one V-band MMW (60 GHz) for the applications of the high data-rate transmission systems.

  2. A novel radio over fiber system with DWDM mm-wave generation and wavelength reuse for upstream data connection.

    Science.gov (United States)

    Chen, Lin; Lei, Xiaoyan; Wen, Shuangchun; Yu, Jianguo

    2007-04-30

    We proposed and experimentally demonstrated a novel radio-over-fiber architecture using an electrical mixer and an optical intensity modulator based on double side-band modulation scheme to generate dense wavelength-division multiplexing (DWDM) optical millimeter for carrying downstream data and centralized lightwave for carrying upstream data. Since the remaining optical carriers with high power have been reused, the optical power is effectively utilized; therefore the system cost can be reduced.

  3. SDN based millimetre wave radio over fiber (RoF) network

    Science.gov (United States)

    Amate, Ahmed; Milosavljevic, Milos; Kourtessis, Pandelis; Robinson, Matthew; Senior, John M.

    2015-01-01

    This paper introduces software-defined, millimeter Wave (mm-Wave) networks with Radio over Fiber (RoF) for the delivery of gigabit connectivity required to develop fifth generation (5G) mobile. This network will enable an effective open access system allowing providers to manage and lease the infrastructure to service providers through unbundling new business models. Exploiting the inherited benefits of RoF, complete base station functionalities are centralized at the edges of the metro and aggregation network, leaving remote radio heads (RRHs) with only tunable filtering and amplification. A Software Defined Network (SDN) Central Controller (SCC) is responsible for managing the resource across several mm-Wave Radio Access Networks (RANs) providing a global view of the several network segments. This ensures flexible resource allocation for reduced overall latency and increased throughput. The SDN based mm-Wave RAN also allows for inter edge node communication. Therefore, certain packets can be routed between different RANs supported by the same edge node, reducing latency. System level simulations of the complete network have shown significant improvement of the overall throughput and SINR for wireless users by providing effective resource allocation and coordination among interfering cells. A new Coordinated Multipoint (CoMP) algorithm exploiting the benefits of the SCC global network view for reduced delay in control message exchange is presented, accounting for a minimum packet delay and limited Channel State Information (CSI) in a Long Term Evolution-Advanced (LTE-A), Cloud RAN (CRAN) configuration. The algorithm does not require detailed CSI feedback from UEs but it rather considers UE location (determined by the eNB) as the required parameter. UE throughput in the target sector is represented using a Cumulative Distributive Function (CDF). The drawn characteristics suggest that there is a significant 60% improvement in UE cell edge throughput following the

  4. Differential Service in a Bidirectional Radio-over-Fiber System over a Spectral-Amplitude-Coding OCDMA Network

    Directory of Open Access Journals (Sweden)

    Chao-Chin Yang

    2016-10-01

    Full Text Available A new scheme of radio-over-fiber (RoF network based on spectral-amplitude-coding (SAC optical code division multiple access (OCDMA is herein proposed. Differential service is provided by a power control scheme that classifies users into several classes and assigns each of them with a specific power level. Additionally, the wavelength reuse technique is adapted to support bidirectional transmission and reduce base station (BS cost. Both simulation and numerical results show that significantly differential quality-of-service (QoS in bit-error rate (BER is achieved in both downlink and uplink transmissions.

  5. Cross stratum resources protection in fog-computing-based radio over fiber networks for 5G services

    Science.gov (United States)

    Guo, Shaoyong; Shao, Sujie; Wang, Yao; Yang, Hui

    2017-09-01

    In order to meet the requirement of internet of things (IoT) and 5G, the cloud radio access network is a paradigm which converges all base stations computational resources into a cloud baseband unit (BBU) pool, while the distributed radio frequency signals are collected by remote radio head (RRH). A precondition for centralized processing in the BBU pool is an interconnection fronthaul network with high capacity and low delay. However, it has become more complex and frequent in the interaction between RRH and BBU and resource scheduling among BBUs in cloud. Cloud radio over fiber network has been proposed in our previous work already. In order to overcome the complexity and latency, in this paper, we first present a novel cross stratum resources protection (CSRP) architecture in fog-computing-based radio over fiber networks (F-RoFN) for 5G services. Additionally, a cross stratum protection (CSP) scheme considering the network survivability is introduced in the proposed architecture. The CSRP with CSP scheme can effectively pull the remote processing resource locally to implement the cooperative radio resource management, enhance the responsiveness and resilience to the dynamic end-to-end 5G service demands, and globally optimize optical network, wireless and fog resources. The feasibility and efficiency of the proposed architecture with CSP scheme are verified on our software defined networking testbed in terms of service latency, transmission success rate, resource occupation rate and blocking probability.

  6. A Study of Dispersion Compensation of Polarization Multiplexing-Based OFDM-OCDMA for Radio-over-Fiber Transmissions.

    Science.gov (United States)

    Yen, Chih-Ta; Chen, Wen-Bin

    2016-09-07

    Chromatic dispersion from optical fiber is the most important problem that produces temporal skews and destroys the rectangular structure of code patterns in the spectra-amplitude-coding-based optical code-division multiple-access (SAC-OCDMA) system. Thus, the balance detection scheme does not work perfectly to cancel multiple access interference (MAI) and the system performance will be degraded. Orthogonal frequency-division multiplexing (OFDM) is the fastest developing technology in the academic and industrial fields of wireless transmission. In this study, the radio-over-fiber system is realized by integrating OFDM and OCDMA via polarization multiplexing scheme. The electronic dispersion compensation (EDC) equalizer element of OFDM integrated with the dispersion compensation fiber (DCF) is used in the proposed radio-over-fiber (RoF) system, which can efficiently suppress the chromatic dispersion influence in long-haul transmitted distance. A set of length differences for 10 km-long single-mode fiber (SMF) and 4 km-long DCF is to verify the compensation scheme by relative equalizer algorithms and constellation diagrams. In the simulation result, the proposed dispersion mechanism successfully compensates the dispersion from SMF and the system performance with dispersion equalizer is highly improved.

  7. Digital radio-over-fiber system with multi-pulse Manchester encoding-assisted delta-sigma modulation.

    Science.gov (United States)

    Jang, Seunghyun; Park, Bonghyuk; Hong, Songcheol

    2017-04-03

    Two ∆Σ-modulated digital radio-over-fiber (DRoF) transmission systems that employ a multi-pulse Manchester encoder are proposed and experimentally evaluated. With a two-step modulation process comprised of ∆Σ modulation and multi-pulse Manchester encoding, a high frequency replica or image of a ∆Σ-digitized analog communication signal can be transmitted without significant power loss. This is achieved by exploiting the spectral characteristics of the modified Manchester code. For comparative analysis, a conventional ∆Σ-modulation-based DRoF system is also evaluated. Based on the evaluation results, the proposed DRoF systems more significantly improve the reliability and flexibility of the RoF system by providing higher power margins or by making the DRoF system implementation more cost-effective and easier to perform on account of the low-frequency requirement for electronics and optical transceivers.

  8. Optically Generated Single Side-Band Radio-over-Fiber Transmission of 60Gbit/s over 50m at W-Band

    DEFF Research Database (Denmark)

    Puerta Ramírez, Rafael; Rommel, Simon; Vegas Olmos, Juan José

    2017-01-01

    60 Gbit/s single side-band multi-band CAP radio-over-fiber transmission at W-band is demonstrated. A spectral efficiency of 3.8 bit/s/Hz and bit error rates below 3.8×10-3 are achieved after 50 m wireless transmission.......60 Gbit/s single side-band multi-band CAP radio-over-fiber transmission at W-band is demonstrated. A spectral efficiency of 3.8 bit/s/Hz and bit error rates below 3.8×10-3 are achieved after 50 m wireless transmission....

  9. Performance evaluation of a real time OFDM radio over fiber system at 2.5 GHz using software defined radio SDR

    DEFF Research Database (Denmark)

    David Cepeda, Juan; Rodriguez, Santiago Isaac; Rico-Martinez, Monica

    2017-01-01

    This paper presents the implementation of an OFDM radio over fiber (RoF) system at 2.5 GHz using software defined radio (SDR). In this work, first we present an introduction of the main concepts about radio over fiber and an orthogonal frequency-division multiplexing (OFDM) system at 2.5 GHz......, then we present a comparison of an OFDM RoF system in three scenarios, modifying the wireless distances and the optical fiber distance in order to evaluate the performance of the system taking into account the symbol error rate (SER) vs signal to noise ratio (SNR) curves....

  10. Network Management System for (FUTON-like) Radio-over-Fiber Infrastructure

    DEFF Research Database (Denmark)

    Santiago, Carlos; Gangopadhyay, Bodhisattwa; Ramkumar, Venkata

    2010-01-01

    operational costs. The RoF Network Manager manages the network equipment on the optical front haul between the Central Unit (CU) and all Remote Antenna Units (RAU)s connected by it, as well as the communication links, while enabling end-to-end service problem resolution and service quality management...... by the FUTON Middleware. Although a significant amount of prior research work can be found in the literature related to RoF, there is still significant lack of technologies concerning RoF networks management. RoF Manager and its sub-systems target to fill such gap, proposing a novel concept in the form...... of Channel Forwarding Table (CFT). RoF Manager follows an autonomous and generic network management framework, designed to be scalable in terms of adding new network elements (NEs). It targets multi-technology, multi-service and multi-vendor NEs in the network using Simple Network Management Protocol (SNMP...

  11. On the capacity of MIMO-OFDM based diversity and spatial multiplexing in Radio-over-Fiber system

    Science.gov (United States)

    El Yahyaoui, Moussa; El Moussati, Ali; El Zein, Ghaïs

    2017-11-01

    This paper proposes a realistic and global simulation to predict the behavior of a Radio over Fiber (RoF) system before its realization. In this work we consider a 2 × 2 Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) RoF system at 60 GHz. This system is based on Spatial Diversity (SD) which increases reliability (decreases probability of error) and Spatial Multiplexing (SMX) which increases data rate, but not necessarily reliability. The 60 GHz MIMO channel model employed in this work based on a lot of measured data and statistical analysis named Triple-S and Valenzuela (TSV) model. To the authors best knowledge; it is the first time that this type of TSV channel model has been employed for 60 GHz MIMO-RoF system. We have evaluated and compared the performance of this system according to the diversity technique, modulation schemes, and channel coding rate for Line-Of-Sight (LOS) desktop environment. The SMX coded is proposed as an intermediate system to improve the Signal to Noise Ratio (SNR) and the data rate. The resulting 2 × 2 MIMO-OFDM SMX system achieves a higher data rate up to 70 Gb/s with 64QAM and Forward Error Correction (FEC) limit of 10-3 over 25-km fiber transmission followed by 3-m wireless transmission using 7 GHz bandwidth of millimeter wave band.

  12. Experimental demonstration of multi-dimensional resources integration for service provisioning in cloud radio over fiber network

    Science.gov (United States)

    Yang, Hui; Zhang, Jie; Ji, Yuefeng; He, Yongqi; Lee, Young

    2016-07-01

    Cloud radio access network (C-RAN) becomes a promising scenario to accommodate high-performance services with ubiquitous user coverage and real-time cloud computing in 5G area. However, the radio network, optical network and processing unit cloud have been decoupled from each other, so that their resources are controlled independently. Traditional architecture cannot implement the resource optimization and scheduling for the high-level service guarantee due to the communication obstacle among them with the growing number of mobile internet users. In this paper, we report a study on multi-dimensional resources integration (MDRI) for service provisioning in cloud radio over fiber network (C-RoFN). A resources integrated provisioning (RIP) scheme using an auxiliary graph is introduced based on the proposed architecture. The MDRI can enhance the responsiveness to dynamic end-to-end user demands and globally optimize radio frequency, optical network and processing resources effectively to maximize radio coverage. The feasibility of the proposed architecture is experimentally verified on OpenFlow-based enhanced SDN testbed. The performance of RIP scheme under heavy traffic load scenario is also quantitatively evaluated to demonstrate the efficiency of the proposal based on MDRI architecture in terms of resource utilization, path blocking probability, network cost and path provisioning latency, compared with other provisioning schemes.

  13. High-throughput and low-latency 60GHz small-cell network architectures over radio-over-fiber technologies

    Science.gov (United States)

    Pleros, N.; Kalfas, G.; Mitsolidou, C.; Vagionas, C.; Tsiokos, D.; Miliou, A.

    2017-01-01

    Future broadband access networks in the 5G framework will need to be bilateral, exploiting both optical and wireless technologies. This paper deals with new approaches and synergies on radio-over-fiber (RoF) technologies and how those can be leveraged to seamlessly converge wireless technology for agility and mobility with passive optical networks (PON)-based backhauling. The proposed convergence paradigm is based upon a holistic network architecture mixing mm-wave wireless access with photonic integration, dynamic capacity allocation and network coding schemes to enable high bandwidth and low-latency fixed and 60GHz wireless personal area communications for gigabit rate per user, proposing and deploying on top a Medium-Transparent MAC (MT-MAC) protocol as a low-latency bandwidth allocation mechanism. We have evaluated alternative network topologies between the central office (CO) and the access point module (APM) for data rates up to 2.5 Gb/s and SC frequencies up to 60 GHz. Optical network coding is demonstrated for SCM-based signaling to enhance bandwidth utilization and facilitate optical-wireless convergence in 5G applications, reporting medium-transparent network coding directly at the physical layer between end-users communicating over a RoF infrastructure. Towards equipping the physical layer with the appropriate agility to support MT-MAC protocols, a monolithic InP-based Remote Antenna Unit optoelectronic PIC interface is shown that ensures control over the optical resource allocation assisting at the same time broadband wireless service. Finally, the MT-MAC protocol is analysed and simulation and analytical theoretical results are presented that are found to be in good agreement confirming latency values lower than 1msec for small- to mid-load conditions.

  14. Enabling technologies for millimeter-wave radio-over-fiber systems in next generation heterogeneous mobile access networks

    Science.gov (United States)

    Zhang, Junwen; Yu, Jianjun; Wang, Jing; Xu, Mu; Cheng, Lin; Lu, Feng; Shen, Shuyi; Yan, Yan; Cho, Hyunwoo; Guidotti, Daniel; Chang, Gee-kung

    2017-01-01

    Fifth-generation (5G) wireless access network promises to support higher access data rate with more than 1,000 times capacity with respect to current long-term evolution (LTE) systems. New radio-access-technologies (RATs) based on higher carrier frequencies to millimeter-wave (MMW) radio-over-fiber, and carrier-aggregation (CA) using multi-band resources are intensively studied to support the high data rate access and effectively use of frequency resources in heterogeneous mobile network (Het-Net). In this paper, we investigate several enabling technologies for MMW RoF systems in 5G Het-Net. Efficient mobile fronthaul (MFH) solutions for 5G centralized radio access network (C-RAN) and beyond are proposed, analyzed and experimentally demonstrated based on the analog scheme. Digital predistortion based on memory polynomial for analog MFH linearization are presented with improved EVM performances and receiver sensitivity. We also propose and experimentally demonstrate a novel inter-/intra- RAT CA scheme for 5G Het- Net. The real-time standard 4G-LTE signal is carrier-aggregated with three broadband 60GHz MMW signals based on proposed optical-domain band-mapping method. RATs based on new waveforms have also been studied here to achieve higher spectral-efficiency (SE) in asynchronous environments. Full-duplex asynchronous quasi-gapless carrier aggregation scheme for MMW ROF inter-/intra-RAT based on the FBMC is also presented with 4G-LTE signals. Compared with OFDM-based signals with large guard-bands, FBMC achieves higher spectral-efficiency with better EVM performance at less received power and smaller guard-bands.

  15. Radio over fiber link with adaptive order n‐QAM optical phase modulated OFDM and digital coherent detection

    DEFF Research Database (Denmark)

    Arlunno, Valeria; Borkowski, Robert; Guerrero Gonzalez, Neil

    2011-01-01

    Successful digital coherent demodulation of asynchronous optical phase‐modulated adaptive order QAM (4, 16, and 64) orthogonal frequency division multiplexing signals is achieved by a single reconfigurable digital receiver after 78 km of optical deployed fiber transmission.......Successful digital coherent demodulation of asynchronous optical phase‐modulated adaptive order QAM (4, 16, and 64) orthogonal frequency division multiplexing signals is achieved by a single reconfigurable digital receiver after 78 km of optical deployed fiber transmission....

  16. 40 Gb/s W-band (75-110 GHz) 16-QAM radio-over-fiber signal generation and its wireless transmission.

    Science.gov (United States)

    Kanno, Atsushi; Inagaki, Keizo; Morohashi, Isao; Sakamoto, Takahide; Kuri, Toshiaki; Hosako, Iwao; Kawanishi, Tetsuya; Yoshida, Yuki; Kitayama, Ken-ichi

    2011-12-12

    The generation of a 40-Gb/s 16-QAM radio-over-fiber (RoF) signal and its demodulation of the wireless signal transmitted over free space of 30 mm in W-band (75-110 GHz) is demonstrated. The 16-QAM signal is generated by a coherent polarization synthesis method using a dual-polarization QPSK modulator. A combination of the simple RoF generation and the versatile digital receiver technique is suitable for the proposed coherent optical/wireless seamless network. © 2011 Optical Society of America

  17. Bidirectional Radio-Over-Fiber System With Phase-Modulation Downlink and RF Oscillator-Free Uplink Using a Reflective SOA

    DEFF Research Database (Denmark)

    Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

    2008-01-01

    We propose and demonstrate a bidirectional radio-over-fiber (RoF) system based on a reflective semiconductor optical amplifier (RSOA). In this system, phase-modulated 5.25-GHz radio frequency (RF) carrying 850 Mb/s is used for the downstream signal. Optical envelope detection of 10-GHz RF carryin......-effective. The experimental results indicate that after simultaneous transmission of downstream and upstream signals over 25-km fiber, the receiver sensitivities are -22 and -14.5 dBm, respectively....

  18. Generation and transmission of 3 × 3 W-Band multi-input multi-output orthogonal frequency division multiplexing-radio-over-fiber signals using micro-ring resonators.

    Science.gov (United States)

    Alavi, S E; Amiri, I S; Ahmad, H; Supa'at, A S M; Fisal, N

    2014-12-01

    Using the micro-ring resonator (MRR) system, the single and multi-carriers at frequencies of f(1)=192.898, f(2)=192.990, f(3)=193.1, f(4)=193.315, and f(5)=193.537  THz with a free spectral range (FSR) of 92, 110, 215, and 222 GHz, respectively, are generated to be suitable for a radio-over-fiber (RoF) system based on multi-input multi-output (MIMO) with orthogonal frequency division multiplexing (OFDM). Demonstrated are the concepts of all-optical MIMO signal generation and its transmission over a 50 km single mode fiber (SMF) optical link and an up to 3 m wireless link. Sixty-four multi-carriers are used in the all-optical generation of three MIMO W-Band RF signals, where the single carriers (f(3)-f(5)) transport the signals over the RoF link. The bit error rate (BER) of the overall system performance is discussed; thus, the transmission of MIMO signals is feasible for up to an SMF path 50 km long and a wireless distance of 3 m.

  19. Coding for stable transmission of W-band radio-over-fiber system using direct-beating of two independent lasers.

    Science.gov (United States)

    Yang, L G; Sung, J Y; Chow, C W; Yeh, C H; Cheng, K T; Shi, J W; Pan, C L

    2014-10-20

    We demonstrate experimentally Manchester (MC) coding based W-band (75 - 110 GHz) radio-over-fiber (ROF) system to reduce the low-frequency-components (LFCs) signal distortion generated by two independent low-cost lasers using spectral shaping. Hence, a low-cost and higher performance W-band ROF system is achieved. In this system, direct-beating of two independent low-cost CW lasers without frequency tracking circuit (FTC) is used to generate the millimeter-wave. Approaches, such as delayed self-heterodyne interferometer and heterodyne beating are performed to characterize the optical-beating-interference sub-terahertz signal (OBIS). Furthermore, W-band ROF systems using MC coding and NRZ-OOK are compared and discussed.

  20. Experimental demonstration of 24-Gb/s CAP-64QAM radio-over-fiber system over 40-GHz mm-wave fiber-wireless transmission.

    Science.gov (United States)

    Zhang, Junwen; Yu, Jianjun; Chi, Nan; Li, Fan; Li, Xinying

    2013-11-04

    We propose and demonstrate a novel CAP-ROF system based on multi-level carrier-less amplitude and phase modulation (CAP) 64QAM with high spectrum efficiency for mm-wave fiber-wireless transmission. The performance of novel CAP modulation with high order QAM, for the first time, is investigated in the mm-wave fiber-wireless transmission system. One I/Q modulator is used for mm-wave generation and base-band signal modulation based on optical carrier suppression (OCS) and intensity modulation. Finally, we demonstrated a 24-Gb/s CAP-64QAM radio-over-fiber (ROF) system over 40-km stand single-mode-fiber (SMMF) and 1.5-m 38-GHz wireless transmission. The system operation factors are also experimentally investigated.

  1. Laser-phase-fluctuation-insensitive offset-frequency-spaced two-tone optical coherent detection scheme and its transmission for radio-over-fiber systems.

    Science.gov (United States)

    Kuri, Toshiaki; Sakamoto, Takahide; Kawanishi, Tetsuya

    2015-09-21

    We propose a new optical coherent detection scheme with a "two-tone" local light, which is also in principle insensitive to the laser phase fluctuation and is assisted by the digital signal processing technique for radio-over-fiber (RoF) systems. The main feature of our proposal is that the frequency separation of the two-tone local light is different from that of the RoF signal, which is called "offset-frequency-spaced" in this paper. First, we explain the principle of our new proposal and experimentally demonstrate the data recovery. Then, the influence of the frequency detuning between photo-detected modulated and unmodulated signals is discussed. Moreover, the transmission performance with an error vector magnitude (EVM) is evaluated for the optical coherent detection of a 10-Gbaud quadrature-phase-shift-keying RoF signal after a 20-km-long standard single-mode fiber transmission.

  2. Performance of a 60-GHz DCM-OFDM and BPSK-Impulse Ultra-Wideband System with Radio-Over-Fiber and Wireless Transmission Employing a Directly-Modulated VCSEL

    DEFF Research Database (Denmark)

    Beltrán, Marta; Jensen, Jesper Bevensee; Yu, Xianbin

    2011-01-01

    The performance of radio-over-fiber optical transmission employing vertical-cavity surface-emitting lasers (VCSELs), and further wireless transmission, of the two major ultra-wideband (UWB) implementations is reported when operating in the 60-GHz radio band. Performance is evaluated at 1.44 Gbit...... good tolerance to chromatic dispersion due to the chirp characteristics of electro-optical conversion when a directly-modulated VCSEL is employed. The performance comparison indicates that BPSK-IR UWB exhibits better tolerance to optical transmission impairments requiring lower received optical power...

  3. Hand held analog television over WiMAX executed in SW

    NARCIS (Netherlands)

    Iancu, D.; Ye, H.; Senthilvelan, M.; Kotlyar, V.; Glossner, J.; Moudgill, M.; Agrawal, S.; Jinturkar, S.; Iancu, A.; Ramadurai, V.

    2007-01-01

    This paper describes a device capable of performing the following tasks: it samples and decodes the composite video analog TV signal, it encodes the resulting RGB data into a MPEG-4 stream and sends it over a WiMAX link. On the other end of the link a similar device receives the WiMAX signal, in

  4. QoS Management and Control for an All-IP WiMAX Network Architecture: Design, Implementation and Evaluation

    Directory of Open Access Journals (Sweden)

    Thomas Michael Bohnert

    2008-01-01

    Full Text Available The IEEE 802.16 standard provides a specification for a fixed and mobile broadband wireless access system, offering high data rate transmission of multimedia services with different Quality-of-Service (QoS requirements through the air interface. The WiMAX Forum, going beyond the air interface, defined an end-to-end WiMAX network architecture, based on an all-IP platform in order to complete the standards required for a commercial rollout of WiMAX as broadband wireless access solution. As the WiMAX network architecture is only a functional specification, this paper focuses on an innovative solution for an end-to-end WiMAX network architecture offering in compliance with the WiMAX Forum specification. To our best knowledge, this is the first WiMAX architecture built by a research consortium globally and was performed within the framework of the European IST project WEIRD (WiMAX Extension to Isolated Research Data networks. One of the principal features of our architecture is support for end-to-end QoS achieved by the integration of resource control in the WiMAX wireless link and the resource management in the wired domains in the network core. In this paper we present the architectural design of these QoS features in the overall WiMAX all-IP framework and their functional as well as performance evaluation. The presented results can safely be considered as unique and timely for any WiMAX system integrator.

  5. WiMAX network performance monitoring & optimization

    DEFF Research Database (Denmark)

    Zhang, Qi; Dam, H

    2008-01-01

    In this paper we present our WiMAX (worldwide interoperability for microwave access) network performance monitoring and optimization solution. As a new and small WiMAX network operator, there are many demanding issues that we have to deal with, such as limited available frequency resource, tight ...

  6. Optical coherent and envelope detection for photonic wireless communication links

    DEFF Research Database (Denmark)

    Prince, Kamau; Zibar, Darko; Yu, Xianbin

    We present two novel optical detection techniques for radio over fiber (RoF) communication links. Firstly, we present recent results obtained with optical digital coherent detection of optical phase-modulated ROF signals supporting error-free transmission over 25 km standard SMF with BPSK and QPSK...

  7. WiMax network planning and optimization

    CERN Document Server

    Zhang, Yan

    2009-01-01

    This book offers a comprehensive explanation on how to dimension, plan, and optimize WiMAX networks. The first part of the text introduces WiMAX networks architecture, physical layer, standard, protocols, security mechanisms, and highly related radio access technologies. It covers system framework, topology, capacity, mobility management, handoff management, congestion control, medium access control (MAC), scheduling, Quality of Service (QoS), and WiMAX mesh networks and security. Enabling easy understanding of key concepts and technologies, the second part presents practical examples and illu

  8. Analisis Throughput Varian TCP Pada Model Jaringan WiMAX

    Directory of Open Access Journals (Sweden)

    Medi Taruk

    2016-07-01

    Full Text Available Transmission Control Protocol (TCP is a protocol that works at the transport layer of the OSI model. TCP was originally designed more destined for a wired network. However, to meet the need for the development of a very fast network technology based on the needs of the use by the user, it needs further development to the use of TCP on wireless devices. One implementation of a wireless network based on Worldwide Interoperability for Microwave Access (WiMAX network is a model that offers a variety advantage, particularly in terms of access speed. In this case, use NS-2 to see throughput at TCP variants tested, namely TCP-Tahoe, TCP-Reno, TCP-Vegas, and TCP-SACK over WiMAX network model, with few observations scenarios. The first is a look at each of these variants throughput of TCP when only one particular variant of the work in the network. Second observe all variants of TCP throughput at the same time and have the equivalent QoS, but with the possibility of a small congestion based on the capacity of the link is made sufficient. Third observed throughput with multi congestion. In WiMAX network has scheduling services are UGS, rtPS and ertPS using UDP protocol and nrtPS and BE using the TCP Protocol. By using the software network simulator (NS-2 to obtain performance comparison TCP protocol-based services on the WiMAX network with QoS parameters are throughput, packet loss, fairness and time delay.

  9. Experimental demonstration of a digital maximum likelihood based feedforward carrier recovery scheme for phase-modulated radio-over-fibre links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2008-01-01

    Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission.......Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission....

  10. WiMAX technology and network evolution

    CERN Document Server

    Etemad, Kamran

    2010-01-01

    WiMAX, the Worldwide Interoperability for Microwave Access, represents a paradigm shift in telecommunications technology. It offers the promise of cheaper, smaller, and simpler technology compared to existing broadband options such as DSL, cable, fiber, and 3G wireless.

  11. Comparative Performance Evaluation of TCP Variants in WiMAX (and WLANs Network Configurations

    Directory of Open Access Journals (Sweden)

    Konstantinos Tsiknas

    2012-01-01

    Full Text Available An important application for the IEEE 802.16 technology (also called WiMAX is to provide high-speed access to the Internet where the transmission control protocol (TCP is the core transport protocol. In this paper we study through extensive simulation scenarios the performance characteristics of five representative TCP schemes, namely, TCP New Reno, Vegas, Veno, Westwood, and BIC, in WiMAX (and WLANs networks, under the conditions of correlated wireless errors, asymmetric end-to-end capabilities, and link congestion. The target is to evaluate how the above conditions would affect the TCP congestion control and suggest the best schemes to be employed in WiMAX networks.

  12. WiMax taking wireless to the max

    CERN Document Server

    Pareek, Deepak

    2006-01-01

    With market value expected to reach 5 billion by 2007 and the endorsement of some of the biggest names in telecommunications, World Interoperability for Microwave Access (WiMAX) is poised to change the broadband wireless landscape. But how much of WiMAX's touted potential is merely hype? Now that several pre-WiMAX networks have been deployed, what are the operators saying about QoS and ROI? How and when will device manufacturers integrate WiMAX into their products? What is the business case for using WiMAX rather than any number of other established wireless alternatives?WiMAX: Taking Wireless

  13. Using WiMAX Technology for E-Learning Solutions

    Directory of Open Access Journals (Sweden)

    Paul POCATILU

    2010-07-01

    Full Text Available WiMAX technology is the only solution for isolated locations where e-learning distributed platforms need to be used. This paper focuses on security issues for e-learning solutions, especially when WiMAX technology is used.

  14. Linearization Technologies for Broadband Radio-Over-Fiber Transmission Systems

    OpenAIRE

    Xiupu Zhang; Ran Zhu; Dongyan Shen; Taijun Liu

    2014-01-01

    Linearization technologies that can be used for linearizing RoF transmission are reviewed. Three main linearization methods, i.e. electrical analog linearization, optical linearization, and electrical digital linearization are presented and compared. Analog linearization can be achieved using analog predistortion circuits, and can be used for suppression of odd order nonlinear distortion components, such as third and fifth order. Optical linearization includes mixed-polarization, dual-wavelen...

  15. Handoff Management in Radio over Fiber 60 GHz Indoor Networks

    NARCIS (Netherlands)

    Bien, V.Q.

    2014-01-01

    Because of high data rate multimedia applications such as HD and UHDTV, online games, etc., the future home networks are expected to support short-range gigabit transmission. With the worldwide availability of 5 GHz spectrum at the 60 GHz band, it creates the opportunity for a promising air

  16. Optimizing power efficiency in radio-over-fiber systems

    DEFF Research Database (Denmark)

    Koonen, A. M. J.; Popov, M.; Wessing, Henrik

    2013-01-01

    Fiber-fed radio pico-cells topologies can reduce the overall power consumption of wireless communication networks. Joint optimization of fiber and radio network parts yields an optimum number of pico-cells which minimizes power consumption....

  17. Fair Adaptive Bandwidth and Subchannel Allocation in the WiMAX Uplink

    Directory of Open Access Journals (Sweden)

    Antoni Morell

    2009-01-01

    Full Text Available In some modern communication systems, as it is the case of WiMAX, it has been decided to implement Demand Assignment Multiple Access (DAMA solutions. End-users request transmission opportunities before accessing the system, which provides an efficient way to share system resources. In this paper, we briefly review the PHY and MAC layers of an OFDMA-based WiMAX system, and we propose to use a Network Utility Maximization (NUM framework to formulate the DAMA strategy foreseen in the uplink of IEEE 802.16. Utility functions are chosen to achieve fair solutions attaining different degrees of fairness and to further support the QoS requirements of the services in the system. Moreover, since the standard allocates resources in a terminal basis but each terminal may support several services, we develop a new decomposition technique, the coupled-decompositions method, that obtains the optimal service flow allocation with a small number of iterations (the improvement is significant when compared to other known solutions. Furthermore, since the PHY layer in mobile WiMAX has the means to adapt the transport capacities of the links between the Base Station (BS and the Subscriber Stations (SSs, the proposed PHY-MAC cross-layer design uses this extra degree of freedom in order to enhance the network utility.

  18. Fair Adaptive Bandwidth and Subchannel Allocation in the WiMAX Uplink

    Directory of Open Access Journals (Sweden)

    Morell Antoni

    2009-01-01

    Full Text Available Abstract In some modern communication systems, as it is the case of WiMAX, it has been decided to implement Demand Assignment Multiple Access (DAMA solutions. End-users request transmission opportunities before accessing the system, which provides an efficient way to share system resources. In this paper, we briefly review the PHY and MAC layers of an OFDMA-based WiMAX system, and we propose to use a Network Utility Maximization (NUM framework to formulate the DAMA strategy foreseen in the uplink of IEEE 802.16. Utility functions are chosen to achieve fair solutions attaining different degrees of fairness and to further support the QoS requirements of the services in the system. Moreover, since the standard allocates resources in a terminal basis but each terminal may support several services, we develop a new decomposition technique, the coupled-decompositions method, that obtains the optimal service flow allocation with a small number of iterations (the improvement is significant when compared to other known solutions. Furthermore, since the PHY layer in mobile WiMAX has the means to adapt the transport capacities of the links between the Base Station (BS and the Subscriber Stations (SSs, the proposed PHY-MAC cross-layer design uses this extra degree of freedom in order to enhance the network utility.

  19. Novel Approaches to Enhance Mobile WiMAX Security

    Directory of Open Access Journals (Sweden)

    Taeshik Shon

    2010-01-01

    Full Text Available The IEEE 802.16 Working Group on Broadband Wireless Access Standards released IEEE 802.16-2004 which is a standardized technology for supporting broadband and wireless communication with fixed and nomadic access. After the IEEE 802.16-2004 standard, a new advanced and revised standard was released as the IEEE 802.16e-2005 amendment which is foundation of Mobile WiMAX network supporting handover and roaming capabilities. In the area of security aspects, compared to IEEE 802.16-2004, IEEE 802.16e, called Mobile WiMAX, adopts improved security architecture—PKMv2 which includes EAP authentication, AES-based authenticated encryption, and CMAC or HMAC message protection. However, there is no guarantee that PKMv2-based Mobile WiMAX network will not have security flaws. In this paper, we investigate the current Mobile WiMAX security architecture focusing mainly on pointing out new security vulnerabilities such as a disclosure of security context in network entry, a lack of secure communication in network domain, and a necessity of efficient handover supporting mutual authentication. Based on the investigation results, we propose a novel Mobile WiMAX security architecture, called RObust and Secure MobilE WiMAX (ROSMEX, to prevent the new security vulnerabilities.

  20. Evaluation of Real-Time Services in Mobile WIMAX

    Directory of Open Access Journals (Sweden)

    Z. Naumoski

    2010-06-01

    Full Text Available In this paper we provide a performance analysis for real-time services with a limited bandwidth in a single-cell Mobile WiMAX network. We analyze the most critical performance parameters for real-time services, such as voice over IP. Since the throughput is a given constraint for a real-time service, the focus is on delay and jitter introduced by the Mobile WiMAX technology. We have used different user velocities, including nomadic users as well as mobile users. The main contribution of this paper is that we have shown that Mobile WiMAX can be efficiently used for real-time services with applied admission control and priority over non-real-time traffic, because it is adding a very small portion to the delay budget for the real-time service, as well as it keeps the jitter far below the end-to-end jitter threshold for telephony in a Mobile WiMAX network.

  1. Radio Resource Management in WiMAX Networks

    NARCIS (Netherlands)

    Jorguseski, L.; Prasad, R.

    2010-01-01

    This chapter presents the general Radio Resource Management (RRM) problem in wireless access networks and gives performance evaluations for different downlink resource (sub-carrier) allocation algorithms in WiMAX TDD systems based on OFDMA wireless access. This is particularly important in downlink

  2. WiMAX security and quality of service an end-to-end perspective

    CERN Document Server

    Tang, Seok-Yee; Sharif, Hamid

    2010-01-01

    WiMAX is the first standard technology to deliver true broadband mobility at speeds that enable powerful multimedia applications such as Voice over Internet Protocol (VoIP), online gaming, mobile TV, and personalized infotainment. WiMAX Security and Quality of Service, focuses on the interdisciplinary subject of advanced Security and Quality of Service (QoS) in WiMAX wireless telecommunication systems including its models, standards, implementations, and applications. Split into 4 parts, Part A of the book is an end-to-end overview of the WiMAX architecture, protocol, and system requirements.

  3. Sending Safety Video over WiMAX in Vehicle Communications

    Directory of Open Access Journals (Sweden)

    Jun Steed Huang

    2013-10-01

    Full Text Available This paper reports on the design of an OPNET simulation platform to test the performance of sending real-time safety video over VANET (Vehicular Adhoc NETwork using the WiMAX technology. To provide a more realistic environment for streaming real-time video, a video model was created based on the study of video traffic traces captured from a realistic vehicular camera, and different design considerations were taken into account. A practical controller over real-time streaming protocol is implemented to control data traffic congestion for future road safety development. Our driving video model was then integrated with the WiMAX OPNET model along with a mobility model based on real road maps. Using this simulation platform, different mobility cases have been studied and the performance evaluated in terms of end-to-end delay, jitter and visual experience.

  4. Digital coherent receiver for phase modulated radio-over-fibre optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Yu, Xianbin; Peucheret, Christophe

    2009-01-01

    A novel digital signal processing-based coherent receiver for phase-modulated radio-over-fiber (RoF) optical links is presented and demonstrated experimentally. Error-free demodulation of 50-Mbaud binary phase-shift keying (BPSK) and quadrature phase-shift keying data signal modulated on a 5-GHz...... radio-frequency (RF) carrier is experimentally demonstrated using the proposed digital coherent receiver. Additionally, a wavelength-division-multiplexing (WDM) phase-modulated RoF optical link is experimentally demonstrated. A 3 x50 Mb/s WDM transmission of a BPSK modulated 5-GHz RF carrier is achieved...

  5. PERFORMANCE ANALYSIS OF AI BASED QOS SCHEDULER FOR MOBILE WIMAX

    Directory of Open Access Journals (Sweden)

    D. David Neels Pon Kumar

    2012-09-01

    Full Text Available Interest in broadband wireless access (BWA has been growing due to increased user mobility and the need for data access at all times. IEEE 802.16e based WiMAX networks promise the best available quality of experience for mobile data service users. WiMAX networks incorporate several Quality of Service (QoS mechanisms at the Media Access Control (MAC level for guaranteed services for multimedia viz. data, voice and video. The problem of assuring QoS is how to allocate available resources among users to meet the QoS criteria such as delay, delay jitter, fairness and throughput requirements. IEEE standard does not include a standard scheduling mechanism and leaves it for various implementer differentiations. Although a lot of the real-time and non real-time packet scheduling schemes has been proposed, it needs to be modified to apply to Mobile WiMAX system that supports five kinds of service classes. In this paper, we propose a novel Priority based Scheduling scheme that uses Artificial Intelligence to support various services by considering the QoS constraints of each class. The simulation results show that slow mobility does not affect the performances and faster mobility and the increment in users beyond a particular load have their say in defining average throughput, average per user throughput, fairness index, average end to end delay and average delay jitter. Nevertheless the results are encouraging that the proposed scheme provides QoS support for each class efficiently.

  6. Effective Bandwidth Allocation for WiMAX Mesh Network

    Directory of Open Access Journals (Sweden)

    Hung-Chin Jang

    2010-04-01

    Full Text Available The aim of this paper is to reduce the media access delay in a WiMAX mesh network. We observe that as the number of subscriber stations (SS in a neighborhood increases, the processes of transmission opportunity (TO competition and 3- way handshake are easy to fail. This may degrade transmission efficiency and increase packet transmission delay. Besides, the minislot allocation defined in the WiMAX mesh mode may cause many lower priority services reserve earlier minislots than that of higher priority services like rtPS. This may cause great negative impact on delay-sensitive traffic. In this paper, we design a QoS classifier to enqueue packets according to different QoS service classes, present a dynamic holdoff exponent mechanism to reduce control subframe delay, and propose a Neighborhood-Based Minislot Allocation (NBMA mechanism to reduce data subframe delay. Simulations show that the proposed methodology outperforms that of IEEE 802.16 and Baye's DynExp in delay, jitter and throughput.

  7. LTE, WiMAX and WLAN network design, optimization and performance analysis

    CERN Document Server

    Korowajczuk, Leonhard

    2011-01-01

    A technological overview of LTE and WiMAX LTE, WiMAX and WLAN Network Design, Optimization and Performance Analysis provides a practical guide to LTE and WiMAX technologies introducing various tools and concepts used within. In addition, topics such as traffic modelling of IP-centric networks, RF propagation, fading, mobility, and indoor coverage are explored; new techniques which increase throughput such as MIMO and AAS technology are highlighted; and simulation, network design and performance analysis are also examined. Finally, in the latter part of the book Korowajczuk gives a step-by-step

  8. Experimental evaluation of high speed impulse radio UWB interference on WiMAX narrowband systems

    DEFF Research Database (Denmark)

    Yu, Xianbin; Yin, Xiaoli; Tafur Monroy, Idelfonso

    2010-01-01

    Interference of high speed impulse radio ultrawideband (IR-UWB) on 5.735GHz single carrier 64/256-QAM WiMAX narrowband signals is experimentally investigated. The experimental results indicate that the coexistence of 625Mbps and 2Gbps IR-UWB signals causes penalties of 3dB and 0.5dB respectively ...... to the WiMAX channel. At higher bit rates, IR-UWB technology is therefore expected to reduce its interference on WiMAX signals. This work serves as further motivation for the exploration of IR-UWB systems with higher speed and higher capacity....

  9. Hierarchical Downlink Resource Management Framework for OFDMA based WiMAX Systems

    DEFF Research Database (Denmark)

    Wang, Hua; Iversen, Villy Bæk

    2008-01-01

    IEEE 802.16, known as WiMAX, has received much attention for its capability to support multiple types of applications with diverse QoS requirements. Beyond what the standard has defined, radio resource management (RRM) still remains an open issue. In this paper, we propose a hierarchical downlink...... resource management framework for OFDMA based WiMAX systems. Our framework consists of a dynamic resource allocation (DRA) module and a connection admission control (CAC) module. DRA emphasizes on how to share the limited radio resources in term of subchannels and time slots among WiMAX subscribers...

  10. Deficit Round Robin with Fragmentation Scheduling to Achieve Generalized Weighted Fairness for Resource Allocation in IEEE 802.16e Mobile WiMAX Networks

    Directory of Open Access Journals (Sweden)

    Chakchai So-In

    2010-10-01

    Full Text Available Deficit Round Robin (DRR is a fair packet-based scheduling discipline commonly used in wired networks where link capacities do not change with time. However, in wireless networks, especially wireless broadband networks, i.e., IEEE 802.16e Mobile WiMAX, there are two main considerations violate the packet-based service concept for DRR. First, the resources are allocated per Mobile WiMAX frame. To achieve full frame utilization, Mobile WiMAX allows packets to be fragmented. Second, due to a high variation in wireless channel conditions, the link/channel capacity can change over time and location. Therefore, we introduce a Deficit Round Robin with Fragmentation (DRRF to allocate resources per Mobile WiMAX frame in a fair manner by allowing for varying link capacity and for transmitting fragmented packets. Similar to DRR and Generalized Processor Sharing (GPS, DRRF achieves perfect fairness. DRRF results in a higher throughput than DRR (80% improvement while causing less overhead than GPS (8 times less than GPS. In addition, in Mobile WiMAX, the quality of service (QoS offered by service providers is associated with the price paid. This is similar to a cellular phone system; the users may be required to pay air-time charges. Hence, we have also formalized a Generalized Weighted Fairness (GWF criterion which equalizes a weighted sum of service time units or slots, called temporal fairness, and transmitted bytes, called throughput fairness, for customers who are located in a poor channel condition or at a further distance versus for those who are near the base stations, or have a good channel condition. We use DRRF to demonstrate the application of GWF. These fairness criteria are used to satisfy basic requirements for resource allocation, especially for non real-time traffic. Therefore, we also extend DRRF to support other QoS requirements, such as minimum reserved traffic rate, maximum sustained traffic rate, and traffic priority. For real

  11. Applying FDTD to the Coverage Prediction of WiMAX Femtocells

    Directory of Open Access Journals (Sweden)

    Valcarce Alvaro

    2009-01-01

    Full Text Available Femtocells, or home base stations, are a potential future solution for operators to increase indoor coverage and reduce network cost. In a real WiMAX femtocell deployment in residential areas covered by WiMAX macrocells, interference is very likely to occur both in the streets and certain indoor regions. Propagation models that take into account both the outdoor and indoor channel characteristics are thus necessary for the purpose of WiMAX network planning in the presence of femtocells. In this paper, the finite-difference time-domain (FDTD method is adapted for the computation of radiowave propagation predictions at WiMAX frequencies. This model is particularly suitable for the study of hybrid indoor/outdoor scenarios and thus well adapted for the case of WiMAX femtocells in residential environments. Two optimization methods are proposed for the reduction of the FDTD simulation time: the reduction of the simulation frequency for problem simplification and a parallel graphics processing units (GPUs implementation. The calibration of the model is then thoroughly described. First, the calibration of the absorbing boundary condition, necessary for proper coverage predictions, is presented. Then a calibration of the material parameters that minimizes the error function between simulation and real measurements is proposed. Finally, some mobile WiMAX system-level simulations that make use of the presented propagation model are presented to illustrate the applicability of the model for the study of femto- to macrointerference.

  12. Performance analysis of IMS based LTE and WIMAX integration architectures

    Directory of Open Access Journals (Sweden)

    A. Bagubali

    2016-12-01

    Full Text Available In the current networking field many research works are going on regarding the integration of different wireless technologies, with the aim of providing uninterrupted connectivity to the user anywhere, with high data rates due to increased demand. However, the number of objects like smart devices, industrial machines, smart homes, connected by wireless interface is dramatically increasing due to the evolution of cloud computing and internet of things technology. This Paper begins with the challenges involved in such integrations and then explains the role of different couplings and different architectures. This paper also gives further improvement in the LTE and Wimax integration architectures to provide seamless vertical handover and flexible quality of service for supporting voice, video, multimedia services over IP network and mobility management with the help of IMS networks. Evaluation of various parameters like handover delay, cost of signalling, packet loss,, is done and the performance of the interworking architecture is analysed from the simulation results. Finally, it concludes that the cross layer scenario is better than the non cross layer scenario.

  13. Perencanaan Jaringan Akses Mobile Wimax (Worldwide Interoperability For Microwave Access 2,5 Ghz Untuk Wilayah DKI Jakarta

    Directory of Open Access Journals (Sweden)

    Hesti Susilawati

    2011-05-01

    Full Text Available Standar IEEE 802.16e yang dikenal dengan mobile WiMAX adalah standar broadband wireless access (BWA yang beroperasi pada frekuensi 2 - 6 GHz. Standar ini merupakan pengembangan dari standar WiMAX sebelumnya untuk mendukung mobilitas pengguna. Pada penelitian ini, penulis melakukan perhitungan untuk memprediksi kebutuhan bandwidth untuk pelanggan mobile WiMAX di wilayah DKI Jakarta untuk jangka waktu tiga tahun sejak WiMAX diimplementasikan. Kebutuhan bandwidth ini akan digunakan untuk menentukan jumlah base station yang dibutuhkan dari sisi kapasitas. Penulis juga melakukan perhitungan jumlah base station dari sisi coverage menggunakan persamaan Erceg. Dari hasil perhitungan tersebut, dapat disimpulkan bahwa pada tiga tahun pertama penetrasi WiMAX di Jakarta, kebutuhan jumlah base station dari sisi coverage lebih besar dari pada perhitungan dari sisi kapasitas.

  14. Performance Evaluation of WiMAX Broadband from High Altitude Platform Cellular System and Terrestrial Coexistence Capability

    Directory of Open Access Journals (Sweden)

    T. Hult

    2008-12-01

    Full Text Available The performance obtained from providing worldwide interoperability for microwave access (WiMAX from high altitude platforms (HAPs with multiple antenna payloads is investigated, and the coexistence capability with multiple-operator terrestrial WiMAX deployments is examined. A scenario composed of a single HAP and coexisting multiple terrestrial WiMAX base stations deployed inside the HAP coverage area (with radius of 30 km to provide services to fixed users with the antenna mounted on the roof with a directive antenna to receive signals from HAPs is proposed. A HAP cellular configuration with different possible reuse patterns is established. The coexistence performance is assessed in terms of HAP downlink and uplink performance, interfered by terrestrial WiMAX deployment. Simulation results show that it is effective to deliver WiMAX via HAPs and share the spectrum with terrestrial systems.

  15. Performance Evaluation of WiMAX Broadband from High Altitude Platform Cellular System and Terrestrial Coexistence Capability

    Directory of Open Access Journals (Sweden)

    Yang Z

    2008-01-01

    Full Text Available The performance obtained from providing worldwide interoperability for microwave access (WiMAX from high altitude platforms (HAPs with multiple antenna payloads is investigated, and the coexistence capability with multiple-operator terrestrial WiMAX deployments is examined. A scenario composed of a single HAP and coexisting multiple terrestrial WiMAX base stations deployed inside the HAP coverage area (with radius of 30 km to provide services to fixed users with the antenna mounted on the roof with a directive antenna to receive signals from HAPs is proposed. A HAP cellular configuration with different possible reuse patterns is established. The coexistence performance is assessed in terms of HAP downlink and uplink performance, interfered by terrestrial WiMAX deployment. Simulation results show that it is effective to deliver WiMAX via HAPs and share the spectrum with terrestrial systems.

  16. Performance analysis of aodv, dsdv and aomdv using wimax in NS - 2

    Directory of Open Access Journals (Sweden)

    Madhusrhee B

    2016-06-01

    Full Text Available WiMAX (IEEE 802.16 technology empowers ubiquitous delivery of wireless broadband facility for fixed and mobile users. WiMAX standard describes numerous physical and MAC layer characteristics. Here, an attempt is made to implement some of these physical and MAC layer structures including the mobility extension 802.16e. NS2 (Network Simulator - 2 is chosen as the simulator to implement these features as NS2 provides suitable library to simulate network scenario. The performance of the simulated module is analyzed by running AODV, DSDV and AOMDV routing protocols on a wired - cum - wireless WiMAX scenario. The throughput for each routing protocol is calculated for varying number of mobile nodes or subs criber stations.

  17. Quality of Context Enhancements and Cost Effective Radio over Fiber Network Planning

    DEFF Research Database (Denmark)

    Shawky, Ahmed Sherif Mahmoud

    In Communication networks today there is an endless quest for increased capacity and improved quality. With wireless systems being now popular worldwide for allowing users and devices to communicate and share information with each other irrespective of their location, the development of sustainable...

  18. Integrated Coherent Radio-over-Fiber Units for Millimeter-Wave Wireless Access

    DEFF Research Database (Denmark)

    Stöhr, A.; Babiel, S.; Chuenchom, M.

    2015-01-01

    to provide wireless services within the E-band (60-90 GHz). In detail, GaAs-based single-sideband millimeter-wave Mach-Zehnder modulators, InP-based millimeter-wave photodiodes featuring rectangular waveguide outputs and monolithically integrated low-linewidth tunable laser diodes as well as Si......Ge-based millimeter-wave RF amplifier technology will be reported. In addition, a new coherent optical heterodyne radio-over–fiber scheme is proposed for seamless integration of next generation millimeter-wave wireless access systems into a next generation passive optical network employing dense or even ultra......-dense WDM. We propose and demonstrate novel radio access units (RAU) using coherent optical heterodyne detection for the generation of the millimeter-wave radio signals in the RAUs. The proposed CRoF concept supports the provision of multiple services over a single optical distribution network including...

  19. Optical and millimeter-wave radio seamless MIMO transmission based on a radio over fiber technology.

    Science.gov (United States)

    Kanno, Atsushi; Kuri, Toshiaki; Hosako, Iwao; Kawanishi, Tetsuya; Yoshida, Yuki; Yasumura, Yoshihiro; Kitayama, Ken-ichi

    2012-12-31

    Multi-input multi-output (MIMO) transmission of two millimeter-wave radio signals seamlessly converted from polarization-division-multiplexed quadrature-phase-shift-keying optical signals is successfully demonstrated, where a radio access unit basically consisting of only optical-to-electrical converters and a radio receiver performs total signal equalization of both the optical and the radio paths and demodulation with digital signal processing (DSP). Orthogonally polarized optical components that are directly converted to two-channel radio components can be demultiplexed and demodulated with high-speed DSP as in optical digital coherent detection. 20-Gbaud optical and radio seamless MIMO transmission provides a total capacity of 74.4 Gb/s with a forward error correction overhead of 7%.

  20. 146-GHz millimeter-wave radio-over-fiber photonic wireless transmission system.

    Science.gov (United States)

    Fice, M J; Rouvalis, E; van Dijk, F; Accard, A; Lelarge, F; Renaud, C C; Carpintero, G; Seeds, A J

    2012-01-16

    We report the experimental implementation of a wireless transmission system with a 146-GHz carrier frequency which is generated by optical heterodyning the two modes from a monolithically integrated quantum dash dual-DFB source. The monolithic structure of the device and the inherent low noise characteristics of quantum dash gain material allow us to demonstrate the transmission of a 1 Gbps ON-OFF keyed data signal with the two wavelengths in a free-running state at 146-GHz carrier wave frequency. The tuning range of the device fully covers the W-band (75 - 110 GHz) and the F-band (90 - 140 GHz).

  1. Analisis Unjuk Kerja Horizontal Handover Mobile Wimax Mendukung Layanan Mobile TV

    Directory of Open Access Journals (Sweden)

    Ammatia Risty

    2016-05-01

    Full Text Available IEEE 802.16e-2005 teknologi mobile WiMAX merupakan salah satu alternatif yang dapat memberikan datarate 15 Mbps yang lebih baik daripada teknologi 3G, WLAN, dan lain-lain. Mobile WiMAX juga memberikan cakupan area yang luas. Oleh karena itu, WiMAX mampu memberikan layanan berbagai macam aplikasi multimedia seperti VoIP, IPTV, Video conferencing. dan aplikasi real-time lainnya. Selain itu, Mobile WiMAX juga mendukung mobility secara portable, mobile, dan nomadic. Saat ini IPTV muncul pada mobile phone, yang dinamakan mobile TV dimana layanan IPTV akan dapat diakses dalam keadaan bergerak. Hal itu membutuhkan suatu teknologi yang mendukung mobility namun tetap dapat menerima layanan IPTV dengan baik. Teknologi mobile WiMAX adalah teknologi yang cocok untuk mendukung layanan IPTV khususnya untuk user yang sedang bergerak. Akibat dari user yang bergerak maka memungkinkan user tersebut melakukan handover. Penelitian ini menganalisis parameter unjuk kerja yang mempengaruhi pada mobile TV saat user melakukan  handover  pada jaringan mobile WiMAX seperti jitter, end to end delay, throughput, handover delay dengan skenario perbedaan kecepatan dan perubahan jumlah user dalam satu cakupan area. Berdasarkan hasil simulasi untuk skenario perbedaan kecepatan (maksimum 100 km/jam diperoleh nilai end to end delay sebesar 23.234 ms, jitter sebesar 0.047 ms, throughput sebesar 637.723 Kbps. Sedangkan skenario jumlah user diperoleh nilai end to end delay 27.218 ms, jitter sebesar 0.057 ms, throughput sebesar 558.881 Kbps. Hasil dari kedua skenario menunjukkan bahwa saat kecepatan dan jumlah user naik maka parameter kualitas layanan turun namun masih memenuhi syarat kualitas layanan Mobile TV (IPTV.

  2. Complementing Security Breach of Authentication by Using Shared Authentication Information in Mobile WiMAX Networks

    Science.gov (United States)

    Kim, Youngwook; Lim, Hyoung-Kyu; Bahk, Saewoong

    The signalling protocol vulnerability opens DDoS problem in Mobile WiMAX networks. This letter proposes an authentication method that uses the unrevealed upper 64bits of Cipher-based MAC as a solution. It runs for MSs in idle mode and reduces the calculation complexity by 59% under DDoS attack while incurring 1% overhead under normal condition.

  3. Cross-layer ultrasound video streaming over mobile WiMAX and HSUPA networks.

    Science.gov (United States)

    Alinejad, Ali; Philip, Nada Y; Istepanian, Robert S H

    2012-01-01

    It is well known that the evolution of 4G-based mobile multimedia network systems will contribute significantly to future mobile healthcare (m-health) applications that require high bandwidth and fast data rates. Central to the success of such emerging applications is the compatibility of broadband networks, such as mobile Worldwide Interoperability For Microwave Access (WiMAX) and High-Speed Uplink Packet Access (HSUPA), and especially their rate adaption issues combined with the acceptable real-time medical quality of service requirements. In this paper, we address the relevant challenges of cross-layer design requirements for real-time rate adaptation of ultrasound video streaming in mobile WiMAX and HSUPA networks. A comparative performance analysis of such approach is validated in two experimental m-health test bed systems for both mobile WiMAX and HSUPA networks. The experimental results have shown an improved performance of mobile WiMAX compared to the HSUPA using the same cross-layer optimization approach.

  4. Secure Military Communications on 3G, 4G and WiMAX

    Science.gov (United States)

    2013-09-01

    mobile stations. The security relies on a removable card, called the UMTS integrated security card, and security applications, like USIM, CSIM ( CDMA ... Mobile Security and User Confidentiality for UMTS (EMSUCU) Evaluation ................. 74 3. Secure-Authentication Key Agreement Protocol...27 Figure 11. Mobile WiMAX network, from [9]. ....................................................... 28 Figure 12

  5. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System.

    Science.gov (United States)

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system.

  6. Mobile Telemedicine Implementation with WiMAX Technology: A Case Study of Ghana.

    Science.gov (United States)

    Tchao, Eric Tutu; Diawuo, Kwasi; Ofosu, Willie K

    2017-01-01

    Telemedicine has become an effective means of delivering quality healthcare in the world. Across the African continent, Telemedicine is increasingly being recognized as a way of improving access to quality healthcare. The use of technology to deliver quality healthcare has been demonstrated as an effective way of overcoming geographic barriers to healthcare in pilot Telemedicine projects in certain parts of Kumasi, Ghana. However because of poor network connectivity experienced in the pilot projects, the success of the pilot networks could not be extended to cover the whole city of Kumasi and other surrounding villages. Fortunately, recent deployment of WiMAX in Ghana has delivered higher data rates at longer distances with improved network connectivity. This paper examines the feasibility of using WiMAX in deploying a city wide Mobile Telemedicine solution. The network architecture and network parameter simulations of the proposed Mobile Telemedicine network using WiMAX are presented. Five WiMAX Base Stations have been suggested to give ubiquitous coverage to the proposed Mobile Telemedicine sites in the network using adaptive 4 × 4 MIMO antenna configurations.

  7. Downlink Resource Allocation for Evolved UTRAN and WiMAX Cellular Systems

    NARCIS (Netherlands)

    Jorguseski, L.; Le, T.M.H.; Fledderus, E.R.; Prasad, R.

    2008-01-01

    The future broadband wireless cellular systems evolved UTRAN (E-UTRAN) and WiMAX are receiving a lot of interest in recent years. Both systems deploy orthogonal frequency division multiplex (OFDM) physical layer consisting of large number of mutually orthogonal sub-carriers. This physical layer

  8. A WiMAX Networked UAV Telemetry System for Net-Centric Remote Sensing and Range Surveillance Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A WiMAX networked UAV Telemetry System (WNUTS) is designed for net-centric remote sensing and launch range surveillance applications. WNUTS integrates a MIMO powered...

  9. A cost model for broadband access networks: FTTx versus WiMAX

    Science.gov (United States)

    Pereira, João Paulo Ribeiro

    2007-09-01

    Local communities and governments are taking various steps to fight the so-called "digital divide" between well served urban communities and undeserved areas. In order to make broadband access available to these under served areas, several technical solutions are available with the capacity to provide high speed Internet access, video, telephony services, etc. This paper presents a cost-model and a tool for the evaluation of broadband access technologies (xDSL, HFC, FTTx, WiMAX, PLC and satellite), and compares two technologies: FTTx and WiMAX. Our tool compares these different access technologies in different scenarios, and examining the capital expense and deployment of building access networks with the same requisite performance using each technology. The cost model is limited to the access part of the network. The results obtained by our evaluation tool give the possibility to compare several BB access technologies, and support the decision about which is the better technological solution for a given scenario

  10. Security Enhancement Using Cache Based Reauthentication in WiMAX Based E-Learning System

    Directory of Open Access Journals (Sweden)

    Chithra Rajagopal

    2015-01-01

    Full Text Available WiMAX networks are the most suitable for E-Learning through their Broadcast and Multicast Services at rural areas. Authentication of users is carried out by AAA server in WiMAX. In E-Learning systems the users must be forced to perform reauthentication to overcome the session hijacking problem. The reauthentication of users introduces frequent delay in the data access which is crucial in delaying sensitive applications such as E-Learning. In order to perform fast reauthentication caching mechanism known as Key Caching Based Authentication scheme is introduced in this paper. Even though the cache mechanism requires extra storage to keep the user credentials, this type of mechanism reduces the 50% of the delay occurring during reauthentication.

  11. Capacity Evaluation for IEEE 802.16e Mobile WiMAX

    Directory of Open Access Journals (Sweden)

    Chakchai So-In

    2010-01-01

    Full Text Available We present a simple analytical method for capacity evaluation of IEEE 802.16e Mobile WiMAX networks. Various overheads that impact the capacity are explained and methods to reduce these overheads are also presented. The advantage of a simple model is that the effect of each decision and sensitivity to various parameters can be seen easily. We illustrate the model by estimating the capacity for three sample applications—Mobile TV, VoIP, and data. The analysis process helps explain various features of IEEE 802.16e Mobile WiMAX. It is shown that proper use of overhead reducing mechanisms and proper scheduling can make an order of magnitude difference in performance. This capacity evaluation method can also be used for validation of simulation models.

  12. Analisis Kinerja Subscriber Station WiMAX di Urban Area Bandung

    Directory of Open Access Journals (Sweden)

    DWI ARYANTA

    2017-06-01

    Full Text Available ABSTRAK   Teknologi komunikasi wireless semakin pesat mengalami perkembangan. WiMAX  merupakan suatu teknologi broadband yang didukung oleh standar IEEE 802.16d (802.16-2004 yang mampu memberikan layanan data berkecepatan tinggi hingga 75 Mbps dalam radius maksimal 40-50 km pada bandwidth 20 MHz. Alokasi frekuensi yang dipakai Indonesia untuk jaringan WiMAX  ini ialah 3,3 – 3,4 GHz. Penelitian ini dilakukan dengan melakukan proses pengukuran kinerja perangkat radio WiMAX  yaitu HiMax 331-SS. Proses pengukuran dilakukan antara CPE dan base station dengan antenna sektoral 1200 pada ketinggian 45 m. Lokasi pengukuran dilakukan di beberapa area kota Bandung yang telah ditentukan sebelumnya. Hasil pengukuran memperlihatkan nilai CINR tertinggi adalah 31 dB dengan modulasi 64 QAM – ¾ dan terendah nilai 10 dB dengan modulasi BPSK 1/2. Nilai RSSI tertinggi -54 dBm berada dan nilai RSSI terendah -89 dBm. Nilai throughput tertinggi untuk layanan streaming video sebesar  1000,8 kbps (downlink dengan modulasi 64 QAM – ¾. Nilai delay terendah sebesar 56,247 ms pada kondisi LOS dan tertinggi sebesar 139,5 ms pada kondisi NLOS. Nilai terbesar packet loss sebesar 20% yaitu pada lokasi pengukuran terjauh 14,3 km. Kata Kunci : delay, packet loss, RSSI, CINR, throughput, CPE, WiMAX .   ABSTRACT   Wireless communication technologies have evolved more rapidly. WiMAX  is a broadband technology that is supported by the IEEE standard 802.16-2004/d which is able to provide high speed data services of up to 75 Mbps within a radius of 40-50 km at a maximum bandwidth of 20 MHz. Indonesia frequency allocation used for the WiMAX  network is 3.3 to 3.4 GHz. This study was conducted with the performance measurement process that is Himax 331 WiMAX  radio - SS. Process measurement is made between the CPE and base station sector antennas at a height of 45 m in 1200. Locations measurements performed in several areas of Bandung predetermined. The measurement

  13. High-Capacity Hybrid Optical Fiber-Wireless Communications Links in Access Networks

    DEFF Research Database (Denmark)

    Pang, Xiaodan

    and radio-over-fiber (RoF) systems employing wireless multi-input multi-output (MIMO) multiplexing technologies. Regarding high speed mm-wave links, this thesis focuses on high capacity fiber-wireless transmissions in both the V-band (50-75 GHz) and the Wband (75-110 GHz). Photonic mm-wave signal generation...... techniques with both coherent and incoherent optical sources are studied and demonstrated. Employments of advanced modulation formats including phase-shift keying (PSK), M-quadrature amplitude modulation (QAM) and orthogonal frequency-division multiplexing (OFDM) for high speed photonic-wireless transmission...... techniques. In conclusion, the results presented in the thesis show the feasibility of employing mm-wave signals, advanced modulation formats and spatial multiplexing technologies in next generation high capacity hybrid optical fiber-wireless access systems....

  14. Investigation of a new handover approach in LTE and WiMAX.

    Science.gov (United States)

    Hindia, Mohammad Nour; Reza, Ahmed Wasif; Noordin, Kamarul Ariffin

    2014-01-01

    Nowadays, one of the most important challenges in heterogeneous networks is the connection consistency between the mobile station and the base stations. Furthermore, along the roaming process between the mobile station and the base station, the system performance degrades significantly due to the interferences from neighboring base stations, handovers to inaccurate base station and inappropriate technology selection. In this paper, several algorithms are proposed to improve mobile station performance and seamless mobility across the long-term evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX) technologies, along with a minimum number of redundant handovers. Firstly, the enhanced global positioning system (GPS) and the novel received signal strength (RSS) prediction approaches are suggested to predict the target base station accurately. Then, the multiple criteria with two thresholds algorithm is proposed to prioritize the selection between LTE and WiMAX as the target technology. In addition, this study also covers the intercell and cochannel interference reduction by adjusting the frequency reuse ratio 3 (FRR3) to work with LTE and WiMAX. The obtained results demonstrate high next base station prediction efficiency and high accuracy for both horizontal and vertical handovers. Moreover, the received signal strength is kept at levels higher than the threshold, while maintaining low connection cost and delay within acceptable levels. In order to highlight the combination of the proposed algorithms' performance, it is compared with the existing RSS and multiple criteria handover decision algorithms.

  15. WIMAX TRAFFIC MODEL BASED ON TIME SERIES FOR FORECAST FUTURE VALUES OF TRAFFIC

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Hernández Suarez

    2009-03-01

    Full Text Available El objetivo de esta investigación es demostrar que las series de tiempo son una excelente herramienta para el modelamiento de tráfico de datos en redes Wimax. Para lograr este objetivo se utilizó la metodología de Box-Jenkins, la cual se describe en este artículo. El modelamiento de tráfico Wimax a través de modelos correlacionados como las series de tiempo permiten ajustar gran parte de la dinámica del comportamiento de los datos en una ecuación y con base en esto estimar valores futuros de tráfico. Lo anterior es una ventaja para la planeación de cobertura, reservación de recursos y la realización de un control más oportuno y eficiente en forma integrada a diferentes niveles de la jerarquía funcional de la red de datos Wimax. Como resultado de la investigación se obtuvo un modelo de tráfico ARIMA de orden 18, el cual realizó pronósticos de tráfico con valores del error cuadrático medio relativamente pequeños, para un periodo de 10 días.

  16. Rectangular Ring Antenna Excited by Circular Disc Monopole for WiMAX System

    Directory of Open Access Journals (Sweden)

    Souphanna Vongsack

    2014-01-01

    Full Text Available This research presents a rectangular ring antenna excited by a circular disc monopole (CDM mounted in front of a square reflector. The proposed antenna is designed to cover a frequency range of 2.300–5.825 GHz and thereby is suitable for WiMAX applications. Multiple parametric studies were carried out using the CST Microwave Studio simulation program. A prototype antenna was fabricated and experimented. The measurements were taken and compared with the simulation results, which indicates good agreement between both results. The prototype antenna produces an impedance bandwidth (|S11| < −10 dB that covers the WiMAX frequency range and a constant unidirectional radiation pattern (θ=0° and ∅=90°. The minimum and maximum gains are 3.7 and 8.7 dBi, respectively. The proposed antenna is of compact size and has good unidirectional radiation performance. Thus, it is very suitable for a multitude of WiMAX applications.

  17. Studi Perancangan Jaringan Worldwide Interoperability For Microwave Access (Wimax Di Area Banyumas

    Directory of Open Access Journals (Sweden)

    Alfin Hikmaturokhman

    2012-05-01

    Full Text Available At present the need for higher internet connection along with the age which is growing so fast. Then there is the latest breakthrough in telecomunications that is WiMAX technology is a wireless broadband technology reffered the IEEE 802.16 standard. WiMAX technology comes with a network of excellence in aspects of data access speed, wide area coverage and the presence of QoS is can allocate frequencies in accordance with user needs using OFDM technology. WiMAX technology can reach area far as 50 kilometers, also allows user equipment (customer premise equipment or CPE to get a broadband connection without having a direct path (non line of sight, NLOS to the base station (BS and provides a total data rate of up to 75 Mbps. Results of this Final project assumed that the area where will be design is Banyumas district. Then final project results of the PRX -100.31 dB; the Total Margin of 23.56 dB; Path los of 134.5 dB; gamma (? of 4.375; Frequency correction factor (?PLf of 0,36; antenna correction factor (?PLh is -3,25; Radius Cells (d is approximately 1995 meters; area of cell is at 10,34010495 km2 and the number of cells 133

  18. Downlink Coexistence Performance Assessment and Techniques for WiMAX Services from High Altitude Platform and Terrestrial Deployments

    Directory of Open Access Journals (Sweden)

    D. Grace

    2008-11-01

    Full Text Available We investigate the performance and coexistence techniques for worldwide interoperability for microwave access (WiMAX delivered from high altitude platforms (HAPs and terrestrial systems in shared 3.5 GHz frequency bands. The paper shows that it is possible to provide WiMAX services from individual HAP systems. The coexistence performance is evaluated by appropriate choice of parameters, which include the HAP deployment spacing radius, directive antenna beamwidths based on adopted antenna models for HAPs and receivers. Illustrations and comparisons of coexistence techniques, for example, varying the antenna pointing offset, transmitting and receiving antenna beamwidth, demonstrate efficient ways to enhance the HAP system performance while effectively coexisting with terrestrial WiMAX systems.

  19. Downlink Coexistence Performance Assessment and Techniques for WiMAX Services from High Altitude Platform and Terrestrial Deployments

    Directory of Open Access Journals (Sweden)

    Grace D

    2008-01-01

    Full Text Available Abstract We investigate the performance and coexistence techniques for worldwide interoperability for microwave access (WiMAX delivered from high altitude platforms (HAPs and terrestrial systems in shared 3.5 GHz frequency bands. The paper shows that it is possible to provide WiMAX services from individual HAP systems. The coexistence performance is evaluated by appropriate choice of parameters, which include the HAP deployment spacing radius, directive antenna beamwidths based on adopted antenna models for HAPs and receivers. Illustrations and comparisons of coexistence techniques, for example, varying the antenna pointing offset, transmitting and receiving antenna beamwidth, demonstrate efficient ways to enhance the HAP system performance while effectively coexisting with terrestrial WiMAX systems.

  20. Pemodelan dan Verifikasi Formal Pengaruh Mobility pattern Terhadap Handoff Latency pada Jaringan WiMAX

    Directory of Open Access Journals (Sweden)

    I Nym Saputra Wahyu Wijaya

    2016-01-01

    Full Text Available In order to decrease handoff latency and increase the successful of HHO conventional scheme, a development of handover scheme is done in standard protocol WiMAX IEEE 802.16e by adding mobility pattern. The superiority of handover scheme with mobility pattern can reduce handoff latency up to 50%, mean while the weakness of this scheme is a wrong act in determining target base station are often happen. Simulation can not showing the cause of that error. So, we do formal verification in to hard handover model with mobility pattern.             In this research, behaviour system is modeled with continuous-time Markov chain (CTMC. The model is foccused to aproximating the influence of mobility pattern in to handoff latency from WiMAX hard handover mechanism. In order to set up a series markov chain models handover system can follow steps, such as: represents the state space, give a number in all transitions, generate the rate transition matrix (infinitesimal generator.             Probabilistic model checking in the research are using quantitative properties and qualitative properties. Formal verification concerning properties has relation with handover in WiMAX network showing that 70% from mobile station which doing scanning with mobility pattern are success doing handover. 24% of them doing scanning conventional as a result of wrongness in act determining target base station, so handoff latency which is pictured will bigger than a system that is only use conventional scanning method.

  1. Performance analysis of medical video streaming over mobile WiMAX.

    Science.gov (United States)

    Alinejad, Ali; Philip, N; Istepanian, R H

    2010-01-01

    Wireless medical ultrasound streaming is considered one of the emerging application within the broadband mobile healthcare domain. These applications are considered as bandwidth demanding services that required high data rates with acceptable diagnostic quality of the transmitted medical images. In this paper, we present the performance analysis of a medical ultrasound video streaming acquired via special robotic ultrasonography system over emulated WiMAX wireless network. The experimental set-up of this application is described together with the performance of the relevant medical quality of service (m-QoS) metrics.

  2. A 2.3/3.3 GHz Dual Band Antenna Design for WiMax Applications

    Directory of Open Access Journals (Sweden)

    Adit Kurniawan

    2010-11-01

    Full Text Available A triangular-slot antenna with rectangular patch for 2.3/3.3 GHz WiMax applications has been implemented on DICLAD 527 substrate (relative permittivity εr = 2.5 with 1.524 mm of substrate thickness. A rectangular patch printed on one side of the substrate is fed by a 50 Ω microstrip line and acts as the frequency tuning stub, while the triangular slot is positioned on the opposite side of the substrate, center lined to the rectangular stub. From the measurement results based on VSWR = 2 or equal to the return loss of 9.53 dB, at the lower band of 2.3 GHz the resulting impedance bandwidth is 290 MHz (from 2.16 to 2.45 GHZ and at the upper band of 3.3 GHz is 370 MHz (from 3.31 to 3.68GHz, providing services for 2.3 GHz and 3.3 GHz frequency bands allocated for WiMax applications. The antenna gain measurement at 2.3 GHz frequency band is almost agrees with the simulation result of 3.2 dBi. While at 3.3 GHz the gain is approximately 4.4 dBi and continues to decrease with increasing frequency. The antenna gain measurement achieves maximum of 4.8 dBi (6 dBi from simulation at about 3 GHz. The simulation and measurement results are evaluated and discussed.

  3. Analisis Perbandingan Performansi Penjadwalan Paket Antara Homogeneous Algorithm Dengan Hybrid Algorithm Pada Jaringan Point-To-Multipoint Wimax

    Directory of Open Access Journals (Sweden)

    Dadiek Pranindito

    2014-11-01

    Full Text Available Saat ini, dalam dunia telekomunikasi, (Worldwide Interoperability for Microwave Access WiMaX merupakan teknologi nirkabel yang menyediakan hubungan jalur lebar dalam jarak jauh, memiliki kecepatan akses yang tinggi dan jangkauan yang luas serta menyediakan berbagai macam jenis layanan. Masalah yang menarik dan menantang pada WiMaX adalah dalam hal menyediakan jaminan kualitas pelayanan (QoS untuk jenis layanan yang berbeda dengan bermacam-macam kebutuhan QoS-nya. Untuk memenuhi kebutuhan QoS tersebut, maka diperlukan suatu algoritma penjadwalan. Dalam penelitian ini dilakukan simulasi jaringan WiMaX menerapkan algoritma penjadwalan dengan metode homogeneous algorithm dan hybrid algorithm. Perwakilan pada metode homogeneous algorithm akan menggunakan algoritma penjadwalan Weighted Fair Queuing (WFQ dan Deficit Round Robin (DRR, sedangkan pada metode hybrid algorithm menggunakan penggabungan antara algoritma penjadwalan DRR dan WFQ. Pengujian kinerja algoritma penjadwalan tersebut dilakukan dengan membandingkan kedalam 5 jenis kelas QoS pada WiMAX yaitu UGS,  rtPS, nrtPS, ertPS, dan Best Effort. Dari hasil pengujian, hybrid algorithm memberikan nilai QoS yang lebih baik jika dibandingkan dengan homogeneous algorithm. hybrid algorithm sangat cocok jika diterapkan pada kondisi jaringan yang memiliki trafik dengan paket data yang bervariasi, karena dapat menghasilkan throughput yang tinggi, serta dapat menghasilkan nilai delay dan jitter yang rendah

  4. CINR Performance of Downlink Mobile WiMAX IEEE 802.16e Deployed Using Coexistence Cellular Terrestrial and HAPS

    Directory of Open Access Journals (Sweden)

    I. Iskandar

    2014-11-01

    Full Text Available Deploying WiMAX through High Altitude Platform Station (HAPS system is a new means of wireless delivery method and thus attracting much the attention in a telecommunication society. However delivering WiMAX through the terrestrial network has already been started a few years ago. Therefore, we need to look at the scenario of coexistence system both of HAPS and terrestrial in delivering WiMAX services. This paper evaluates the performance of coexistence system between cellular HAPS and terrestrial for the downlink scenario when they are transmitting WiMAX mobile 802.16e services. Our evaluation is based on the performance simulation of coexistence model using two methods. First method is a footprint exchange between the two systems.The second method is a combination of footprint exchange and HAPS footprint enhancement. The proposed methodsare then evaluated by computer simulation in terms of carrier to interference plus noise ratio (CINR performance. In general, both methods resulting performance enhancement in CINR quality compared with coexistence deployment with normal scenario of the cell configuration used by HAPS and terrestrial. The method of combining footprint exchange and HAPS footprint enhancement is able to improve CINR more than 10 dB compared with the normal footprint configuration for all users location inside the coverage.

  5. Investigation of the SIW technology for low cost 60 GHz radio over fiber based array antenna units

    Science.gov (United States)

    Makris, D.; Tsiakas, P.; Voudouris, K.; Thakur, M. P.; Mikroulis, S.

    2015-01-01

    In this paper, a Substrate Integrated Waveguide (SIW) based photonic antenna suitable for RoF applications is presented. The millimeter-wave design is based on a diplexer, two Chebyshev bandpass filters, one for uplink (61,7GHz to 62,7 GHz) and one for downlink (59,3 GHz to 60,3 GHz) and one common 8x8 Slot array antenna, integrated on the same substrate. E/M simulations of a fully integrated planar RF Front End provide very good results, both in diplexer and filters and in antenna characteristics. Finally, a consideration regarding transition requirements for integration with a coplanar waveguide (CPW) photodiode is being presented.

  6. Simultaneous optical carrier and radio frequency re-modulation in radio-over-fiber systems employing reflective SOA modulators

    DEFF Research Database (Denmark)

    Kassar, Carvalho; Calabretta, Nicola; Tafur Monroy, Idelfonso

    2007-01-01

    We demonstrate an innovative full-duplex radio-over-fibre transmission system employing a reflective SOA to perform simultaneous reusing of the optical carrier and data re-modulation, thus avoiding the use of local radiofrequency oscillator at the station sites.......We demonstrate an innovative full-duplex radio-over-fibre transmission system employing a reflective SOA to perform simultaneous reusing of the optical carrier and data re-modulation, thus avoiding the use of local radiofrequency oscillator at the station sites....

  7. Cost-Efficient DWDM-PON / Mm-Wave Wireless Integration using Coherent Radio-over-Fiber (CRoF)

    DEFF Research Database (Denmark)

    Thakur, Manoj P.; Mikroulis, S.; Renaud, C. C.

    2015-01-01

    This work aims to investigate the performance of millimetre wave (mm-wave) broadband wireless access for seamless integration with the (ultra-dense) WDM infrastructure. By using two uncorrelated lasers, this system concept allows simple implementation that can additionally be improved, if thermal...

  8. Simultaneous transmission of 256-QAM WIMAX at 5.7GHz and optically generated impulse radio UWB over fiber for indoor wireless multi-services

    DEFF Research Database (Denmark)

    Yu, Xianbin; Yin, Xiaoli; Gibbon, Timothy Braidwood

    2010-01-01

    Fiber transmission of simultaneous optically generated FCC compliant 625Mbps impulse radio UWB and 80Mbps 256-QAM IEEE 802.16 WIMAX signals is experimentally demonstrated by using a single directly modulated light source.......Fiber transmission of simultaneous optically generated FCC compliant 625Mbps impulse radio UWB and 80Mbps 256-QAM IEEE 802.16 WIMAX signals is experimentally demonstrated by using a single directly modulated light source....

  9. Driven-Walking for Visually Impaired/Blind People through WiMAX

    Directory of Open Access Journals (Sweden)

    Panagiotis GIOANNIS

    2010-03-01

    Full Text Available It is known that people who are blind/visually impaired find it difficult to move, especially in unknown places. Usually the only help they have is their walking stick (white cane, a guide dog and sometimes special warning sounds or road signals at specific positions. Material and Method: In this paper we are trying to find a solution on how to build an appropriate navigating system for blind people. Results: Based on benefits of powerful properties of mobile WiMAX standard we suggest an important navigate application which can translate a digital visual environment properly for blind/visually impaired users through a plethora of combinations such as voice, brain or tongue signals. Conclusions: We believe that such an idea will be an initial point for a plethora of applications which will eliminate walking disabilities of blind/visually people.

  10. A Paging Indicator Transmission Technique for Mobile WiMAX Systems

    Science.gov (United States)

    Kim, Yeong-Jun; Yoo, Hyun-Il; Woo, Kyung-Soo; Lee, Jung-Ryun; Lee, Heesoo; Cho, Yong-Soo

    In a cellular system, efficient power saving techniques for a mobile station (MS) are necessary because of its inherently limited battery capacity. The paging indicator (PI) transmission scheme in CDMA cellular systems is known to be an effective power saving strategy. However, in OFDM-based cellular systems, the MS has to operate FFT for PI symbol detection, resulting in a significant power consumption. In this letter, a PI transmission technique with reduced power consumption using the preamble in OFDM-based cellular systems, especially for mobile WiMAX systems, is proposed for the MS under power saving mode. Simulations indicate a 30-50% power saving from our proposed PI transmission technique, at the expense of a slight increase in paging response delay.

  11. A 2.3/3.3 GHz Dual Band Antenna Design for WiMax Applications

    Directory of Open Access Journals (Sweden)

    Adit Kurniawan

    2014-10-01

    Full Text Available A triangular-slot antenna with rectangular patch for 2.3/3.3 GHz WiMax applications has been implemented on DICLAD 527 substrate (relative permittivity εr = 2.5 with 1.524 mm of substrate thickness. A rectangular patch printed on one side of the substrate is fed by a 50 Ω microstrip line and acts as the frequency tuning stub, while the triangular slot is positioned on the opposite side of the substrate, center lined to the rectangular stub. From the measurement results based on VSWR = 2 or equal to the return loss of 9.53 dB, at the lower band of 2.3 GHz the resulting impedance bandwidth is 290 MHz (from 2.16 to 2.45 GHZ and at the upper band of 3.3 GHz is  370 MHz (from 3.31 to 3.68GHz, providing services for 2.3 GHz and 3.3 GHz frequency bands allocated for WiMax applications. The antenna gain measurement at 2.3 GHz frequency band is almost agrees with the simulation result of 3.2 dBi. While at 3.3 GHz the gain is approximately 4.4 dBi and continues to decrease with increasing frequency. The antenna gain measurement achieves maximum of 4.8 dBi (6 dBi from simulation at about 3 GHz. The simulation and measurement results are evaluated and discussed.

  12. Analyzing mobile WiMAX base station deployment under different frequency planning strategies

    Science.gov (United States)

    Salman, M. K.; Ahmad, R. B.; Ali, Ziad G.; Aldhaibani, Jaafar A.; Fayadh, Rashid A.

    2015-05-01

    The frequency spectrum is a precious resource and scarce in the communication markets. Therefore, different techniques are adopted to utilize the available spectrum in deploying WiMAX base stations (BS) in cellular networks. In this paper several types of frequency planning techniques are illustrated, and a comprehensive comparative study between conventional frequency reuse of 1 (FR of 1) and fractional frequency reuse (FFR) is presented. These techniques are widely used in network deployment, because they employ universal frequency (using all the available bandwidth) in their base station installation/configuration within network system. This paper presents a network model of 19 base stations in order to be employed in the comparison of the aforesaid frequency planning techniques. Users are randomly distributed within base stations, users' resource mapping and their burst profile selection are based on the measured signal to interference plus-noise ratio (SINR). Simulation results reveal that the FFR has advantages over the conventional FR of 1 in various metrics. 98 % of downlink resources (slots) are exploited when FFR is applied, whilst it is 81 % at FR of 1. Data rate of FFR has been increased to 10.6 Mbps, while it is 7.98 Mbps at FR of 1. The spectral efficiency is better enhanced (1.072 bps/Hz) at FR of 1 than FFR (0.808 bps/Hz), since FR of 1 exploits all the Bandwidth. The subcarrier efficiency shows how many data bits that can be carried by subcarriers under different frequency planning techniques, the system can carry more data bits under FFR (2.40 bit/subcarrier) than FR of 1 (1.998 bit/subcarrier). This study confirms that FFR can perform better than conventional frequency planning (FR of 1) which made it a strong candidate for WiMAX BS deployment in cellular networks.

  13. A Rectangular Ring, Open-Ended Monopole Antenna with Two Symmetric Strips for WLAN and WiMAX Applications

    Directory of Open Access Journals (Sweden)

    Joong-Han Yoon

    2013-01-01

    Full Text Available A triple-band rectangular ring, open-ended monopole antenna with symmetric L strips for wireless local area network (WLAN/Worldwide Interoperability of Microwave Access (WiMAX applications is proposed. The proposed antenna consists of two symmetric folded arms and L strips. Based on the concept, a prototype of the proposed triple antenna has been designed, fabricated, and tested. The numerical and experimental results demonstrated that the proposed antenna satisfied the −10 dB impedance bandwidth requirement while simultaneously covering the WLAN and WiMAX bands. Furthermore, this paper presented and discussed the 2D radiation patterns and 3D gains according to the results of the experiment. The proposed antenna’s peak gain varied between 2.17 and 4.93 dBi, and its average gain varied between −2.97 and −0.53 dBi.

  14. Minimum decoding trellis length and truncation depth of wrap-around Viterbi algorithm for TBCC in mobile WiMAX

    Directory of Open Access Journals (Sweden)

    Liu Yu-Sun

    2011-01-01

    Full Text Available Abstract The performance of the wrap-around Viterbi decoding algorithm with finite truncation depth and fixed decoding trellis length is investigated for tail-biting convolutional codes in the mobile WiMAX standard. Upper bounds on the error probabilities induced by finite truncation depth and the uncertainty of the initial state are derived for the AWGN channel. The truncation depth and the decoding trellis length that yield negligible performance loss are obtained for all transmission rates over the Rayleigh channel using computer simulations. The results show that the circular decoding algorithm with an appropriately chosen truncation depth and a decoding trellis just a fraction longer than the original received code words can achieve almost the same performance as the optimal maximum likelihood decoding algorithm in mobile WiMAX. A rule of thumb for the values of the truncation depth and the trellis tail length is also proposed.

  15. Comparative Analysis between WiMAX and Fiber Optics Backhaul Network Deployment in Developing Countries - The Case of Ghana

    DEFF Research Database (Denmark)

    Adjin, Daniel Michael Okwabi; Williams, Idongesit

    to deploy than mobile technologies. But in many developing countries, there is preference for the deployment of fiber optics rather than a broadband wireless solution for the deployment of broadband internet. Argument is made in this paper using the Expectation Confirmation Theory to reveal the level...... of satisfaction of mobile WiMAX compared to what Fiber optics would bring to rural areas in terms of broadband provisioning, Cost of access, Cost of deployment, Network accessibility and availability. The case of investigation is Northern Ghana due to the proliferation of rural areas in that region...... broadband users have no access to the existing Fibre Optic Cable backhaul access network in the rural due to lack of coverage. Finally, the contribution from this study is that, it is possible to deploy the 2.3GHz -2.6 GHz band of WiMAX Backhaul Access Network Technologies to provide Wireless Broadband...

  16. RLAM: A Dynamic and Efficient Reinforcement Learning-Based Adaptive Mapping Scheme in Mobile WiMAX Networks

    OpenAIRE

    M. Louta; Sarigiannidis, P.; Misra, S.; P. Nicopolitidis; Papadimitriou, G.

    2014-01-01

    WiMAX (Worldwide Interoperability for Microwave Access) constitutes a candidate networking technology towards the 4G vision realization. By adopting the Orthogonal Frequency Division Multiple Access (OFDMA) technique, the latest IEEE 802.16x amendments manage to provide QoS-aware access services with full mobility support. A number of interesting scheduling and mapping schemes have been proposed in research literature. However, they neglect a considerable asset of the OFDMA-based wireless sys...

  17. Automated secured cost effective key refreshing technique to enhance WiMAX privacy key management

    Science.gov (United States)

    Sridevi, B.; Sivaranjani, S.; Rajaram, S.

    2013-01-01

    In all walks of life the way of communication is transformed by the rapid growth of wireless communication and its pervasive use. A wireless network which is fixed and richer in bandwidth is specified as IEEE 802.16, promoted and launched by an industrial forum is termed as Worldwide Interoperability for Microwave Access (WiMAX). This technology enables seamless delivery of wireless broadband service for fixed and/or mobile users. The obscurity is the long delay which occurs during the handoff management in every network. Mobile WiMAX employs an authenticated key management protocol as a part of handoff management in which the Base Station (BS) controls the distribution of keying material to the Mobile Station (MS). The protocol employed is Privacy Key Management Version 2- Extensible Authentication Protocol (PKMV2-EAP) which is responsible for the normal and periodical authorization of MSs, reauthorization as well as key refreshing. Authorization key (AK) and Traffic Encryption key (TEK) plays a vital role in key exchange. When the lifetime of key expires, MS has to request for a new key to BS which in turn leads to repetition of authorization, authentication as well as key exchange. To avoid service interruption during reauthorization , two active keys are transmitted at the same time by BS to MS. The consequences of existing work are hefty amount of bandwidth utilization, time consumption and large storage. It is also endured by Man in the Middle attack and Impersonation due to lack of security in key exchange. This paper designs an automatic mutual refreshing of keys to minimize bandwidth utilization, key storage and time consumption by proposing Previous key and Iteration based Key Refreshing Function (PKIBKRF). By integrating PKIBKRF in key generation, the simulation results indicate that 21.8% of the bandwidth and storage of keys are reduced and PKMV2 mutual authentication time is reduced by 66.67%. The proposed work is simulated with Qualnet model and

  18. Flexible Macroblock Ordering for Context-Aware Ultrasound Video Transmission over Mobile WiMAX

    Science.gov (United States)

    Martini, Maria G.; Hewage, Chaminda T. E. R.

    2010-01-01

    The most recent network technologies are enabling a variety of new applications, thanks to the provision of increased bandwidth and better management of Quality of Service. Nevertheless, telemedical services involving multimedia data are still lagging behind, due to the concern of the end users, that is, clinicians and also patients, about the low quality provided. Indeed, emerging network technologies should be appropriately exploited by designing the transmission strategy focusing on quality provision for end users. Stemming from this principle, we propose here a context-aware transmission strategy for medical video transmission over WiMAX systems. Context, in terms of regions of interest (ROI) in a specific session, is taken into account for the identification of multiple regions of interest, and compression/transmission strategies are tailored to such context information. We present a methodology based on H.264 medical video compression and Flexible Macroblock Ordering (FMO) for ROI identification. Two different unequal error protection methodologies, providing higher protection to the most diagnostically relevant data, are presented. PMID:20827292

  19. On the Verification of a WiMax Design Using Symbolic Simulation

    Directory of Open Access Journals (Sweden)

    Gabriela Nicolescu

    2013-07-01

    Full Text Available In top-down multi-level design methodologies, design descriptions at higher levels of abstraction are incrementally refined to the final realizations. Simulation based techniques have traditionally been used to verify that such model refinements do not change the design functionality. Unfortunately, with computer simulations it is not possible to completely check that a design transformation is correct in a reasonable amount of time, as the number of test patterns required to do so increase exponentially with the number of system state variables. In this paper, we propose a methodology for the verification of conformance of models generated at higher levels of abstraction in the design process to the design specifications. We model the system behavior using sequence of recurrence equations. We then use symbolic simulation together with equivalence checking and property checking techniques for design verification. Using our proposed method, we have verified the equivalence of three WiMax system models at different levels of design abstraction, and the correctness of various system properties on those models. Our symbolic modeling and verification experiments show that the proposed verification methodology provides performance advantage over its numerical counterpart.

  20. Performance Analysis of the Sleep Mode in WiMAX 2 Networks with Multimedia Application

    Directory of Open Access Journals (Sweden)

    Shunfu Jin

    2014-01-01

    Full Text Available We consider the sleep mode with multimedia application in WiMAX 2 networks, where the real-time traffic includes the real-time and the best-effort traffic mixed. We present a queueing model with multiple heterogeneous vacations to characterize the system probability behavior in the networks with multimedia application. Taking into account the correlation of the real-time traffic, we assume the arrival process as a discrete-time Markovian arrival process (D-MAP and analyze this queueing model by using the method of an embedded Markov chain. Then, we present the probability distribution for the number of data packets. Accordingly, we give the formulas for the performance measures in terms of the average response time of data packets, the energy saving ratio, and the standard deviation of the number of data packets. We also develop a cost function to determine the optimal length of the sleep cycle in order to maximize the energy saving ratio while satisfying the Quality of Service (QoS constraint on the average response time of data packets. Finally, we provide numerical results to investigate the influence of the system parameters on the system performance.

  1. Cross-Layer Design of the Inter-RAT Handover between UMTS and WiMAX

    Directory of Open Access Journals (Sweden)

    Bertin Philippe

    2010-01-01

    Full Text Available In future mobile networks, different radio access technologies will have to coexist. IEEE 802.21 MIH (Media-Independent Handover provides primitive mechanisms that ease the implementation of a seamless vertical handover (inter-RAT handover between different radio access technologies. However, it does not specify any handover execution mechanism. The first objective of this paper is to propose a novel MIHF (Media-Independent Handover Function variant, which is renamed interworking (IW sublayer. IW sublayer provides a seamless inter-RAT handover procedure between UMTS and WiMAX systems. It relies on a new intersystem retransmission mechanism with cross-layer interaction ability providing lossless handover while keeping acceptable delays. The second objective of this paper is to design a new TCP snoop agent (TCP Snoop, which interacts with the IW layer in order to mitigate BDP (Bandwidth Delay Product mismatch and to solve spurious RTO (Retransmission TimeOut problems. The cross-layer effects on the handover performance are evaluated by simulations. Our results show that cross-layer interaction between IW layer and TCP Snoop smoothes the handover procedure for TCP traffics. Additionally, this novel inter-RAT cross-layer scheme has the merit of keeping existing TCP protocol stacks unchanged.

  2. On the Modelling of the Mobile WiMAX (IEEE 802.16e Uplink Scheduler

    Directory of Open Access Journals (Sweden)

    Darmawaty Mohd Ali

    2010-01-01

    Full Text Available Packet scheduling has drawn a great deal of attention in the field of wireless networks as it plays an important role in distributing shared resources in a network. The process involves allocating the bandwidth among users and determining their transmission order. In this paper an uplink (UL scheduling algorithm for the Mobile Worldwide Interoperability for Microwave Access (WiMAX network based on the cyclic polling model is proposed. The model in this study consists of five queues (UGS, ertPS, rtPS, nrtPS, and BE visited by a single server. A threshold policy is imposed to the nrtPS queue to ensure that the delay constraint of real time traffic (UGS, ertPS, and rtPS is not violated making this approach original in comparison to the existing contributions. A mathematical model is formulated for the weighted sum of the mean waiting time of each individual queues based on the pseudo-conservation law. The results of the analysis are useful in obtaining or testing approximation for individual mean waiting time especially when queues are asymmetric (where each queue may have different stochastic characteristic such as arrival rate and service time distribution and when their number is large (more than 2 queues.

  3. Ultrawideband Vivaldi Antenna for DVB-T, WLAN, and WiMAX Applications

    Directory of Open Access Journals (Sweden)

    Dalia M. Elsheakh

    2014-01-01

    Full Text Available Compact Vivaldi patch antenna with a parasitic meander line is presented in this paper. A PIN diode switch is used to connect and disconnect ultrahigh frequency band (UHF with ultrawide bandwidth (UWB. The operating frequencies can be switched among different services, depending on the switching states (ON/OFF to add the lower band when required. This antenna is suitable for portable DVB-T which extended from 450 MHz to 850 MHz receiver applications and the WLAN (Wireless Local Area Network IEEE 802.11b,g (5.1–5.8 GHz frequency bands and WiMAX band (3.3–3.8 GHz. The measured reflection coefficient of the proposed antenna is compared with the simulated one; good agreement is observed. Also, simulated radiation pattern of the antenna is presented. All simulations are carried out using the EM commercial simulator, high frequency structure simulator (HFSS ver.13.

  4. Flexible Macroblock Ordering for Context-Aware Ultrasound Video Transmission over Mobile WiMAX.

    Science.gov (United States)

    Martini, Maria G; Hewage, Chaminda T E R

    2010-01-01

    The most recent network technologies are enabling a variety of new applications, thanks to the provision of increased bandwidth and better management of Quality of Service. Nevertheless, telemedical services involving multimedia data are still lagging behind, due to the concern of the end users, that is, clinicians and also patients, about the low quality provided. Indeed, emerging network technologies should be appropriately exploited by designing the transmission strategy focusing on quality provision for end users. Stemming from this principle, we propose here a context-aware transmission strategy for medical video transmission over WiMAX systems. Context, in terms of regions of interest (ROI) in a specific session, is taken into account for the identification of multiple regions of interest, and compression/transmission strategies are tailored to such context information. We present a methodology based on H.264 medical video compression and Flexible Macroblock Ordering (FMO) for ROI identification. Two different unequal error protection methodologies, providing higher protection to the most diagnostically relevant data, are presented.

  5. A CPW-fed Triple-band Antenna for WLAN and WiMAX Applications

    Directory of Open Access Journals (Sweden)

    X.L.Yang

    2014-12-01

    Full Text Available In this letter, a compact printed antenna fed by coplanar waveguide for triple-band is presented. The proposed antenna consists of two rectangular metallic loops in front and a slit square ring on the backside. Tri-band has been achieved, which can be easily tuned by adjusting the sizes of the rectangles. An analysis of equal lumped circuit mechanism as well the triple band operation is provided. Key parameters to tune the resonant frequencies have been identified. The overall dimension of the proposed antenna is 30×26 mm^2. Simulated results show that the presented antenna can cover three separated impedance bandwidths of ~13% at 300 MHz (2.2–2.5 GHz, ~14% at 500 MHz (3.3–3.8 GHz, and ~15% at 800 MHz (5.1–5.9 GHz, which are well applied for both 2.4/5.2/5.8-GHz WLAN bands and 3.5/5.5-GHz WiMAX bands.

  6. Design & Analysis of Microstrip Patch Antenna Using Different Dielectric Materials for WiMAX Communication System

    Directory of Open Access Journals (Sweden)

    Md. Moidul Islam

    2016-03-01

    Full Text Available This Paper presents Microstrip patch antenna for WiMAX communication system which operate at 5.8 GHz frequency band. The main objective of this paper is to design and observe the performance of the designed microstrip patch antenna for different dielectric materials. The size of the designed antenna has been also miniaturized. Better performance is observed for FR4 and dupont-951 dielectric material. For FR4 radiation efficiency is-2.776 dB and total efficiency is -3.026 dB at 5.8 GHz, this indicates better performance. And for dupont-951 the return loss is much lower comparing to the other dielectric materials used in this research, which is -16.609 dB. Also for dupont-951 and FR4, VSWR is found 1.35 and 1.7 respectively which is desirable. Also the size of the antenna has been reduced. In this paper we also observed and analyzed the radiation pattern of far field region, gain, radiation efficiency and total efficiency for different dielectric materials.

  7. Broadband Semielliptical Patch Antenna with Semicircular Ring Slot for WiMax Application

    Directory of Open Access Journals (Sweden)

    Brajraj Shrama

    2014-01-01

    Full Text Available This paper reports the design and analysis of a semielliptical patch antenna modified by cutting semicircular ring slot in patch geometry and obtained results are discussed. The reported antenna is designed on a multilayered substrate material having two glass epoxy FR-4 substrates separated by a thin foam substrate having thickness 1.0 mm. The size of ground plane is 75 mm×75 mm, whereas the patch dimension along major and minor axes is 23.0 mm and 14.0 mm, respectively. The two modes corresponding to resonance frequencies 3.39 GHz and 3.73 GHz are excited to provide wide impedance bandwidth 21.1% with respect to central frequency with stable radiation patterns. The antenna shows circular polarization with axial ratio bandwidth 5.5% and minimum axial ratio value 1.65 dBi. The radiation patterns of proposed antenna are normal to the surface of patch and are almost identical in shape as required for practical applications. The proposed antenna covers entire median band of WiMax communication systems ranges from 3.40 GHz to 3.6 GHz.

  8. A Compact Frequency Reconfigurable Hybrid DRA for LTE/Wimax Applications

    Directory of Open Access Journals (Sweden)

    Sajid Aqeel

    2017-01-01

    Full Text Available A compact hybrid antenna structure with frequency reconfiguration capabilities is presented in this article. The proposed design employs a combination of a rectangular DR element and a coupling slot on the structure’s ground plane (GP. The slot shifts the fundamental DRA mode by introducing a slow wave effect and its resonant behavior helps to achieve an omnidirectional pattern at low frequencies. The slot is loaded with a series of PIN diode switches whose ON/OFF combinations alter the effective slot length. Slot loading with PIN diodes results in frequency reconfiguration of the proposed structure with a large tuning range of 76.2% (between 1.73 and 3.86 GHz. A parametric analysis was performed to investigate the effects of slot length, width, and position on the reflection coefficients of the proposed structure. A prototype of the proposed design was fabricated and results were measured. The measured results show a close agreement with the simulated ones. The proposed design is suitable for DCS 1800 MHz, PCS 1900 MHZ, UMTS, LTE 2500–2700 MHz, and Wimax 3.5 GHz.

  9. High Dynamic Range RF Front End with Noise Cancellation and Linearization for WiMAX Receivers

    Directory of Open Access Journals (Sweden)

    J.-M. Wu

    2012-06-01

    Full Text Available This research deals with verification of the high dynamic range for a heterodyne radio frequency (RF front end. A 2.6 GHz RF front end is designed and implemented in a hybrid microwave integrated circuit (HMIC for worldwide interoperability for microwave access (WiMAX receivers. The heterodyne RF front end consists of a low-noise amplifier (LNA with noise cancellation, an RF bandpass filter (BPF, a downconverter with linearization, and an intermediate frequency (IF BPF. A noise canceling technique used in the low-noise amplifier eliminates a thermal noise and then reduces the noise figure (NF of the RF front end by 0.9 dB. Use of a downconverter with diode linearizer also compensates for gain compression, which increases the input-referred third-order intercept point (IIP3 of the RF front end by 4.3 dB. The proposed method substantially increases the spurious-free dynamic range (DRf of the RF front end by 3.5 dB.

  10. Analysis of control and management plane for hybrid fiber radio architectures

    DEFF Research Database (Denmark)

    Kardaras, Georgios; Pham, Tien Thang; Soler, José

    2010-01-01

    This paper presents the existing Radio over Fiber (RoF) architectures and focuses on the control and management plane of the Remote Antenna Unit (RAU). Broadband wireless standards, such as WiMAX and LTE, incorporate optical technologies following the distributed base station concept. The control...

  11. Resource management framework for QoS scheduling in IEEE 802.16 WiMAX networks

    DEFF Research Database (Denmark)

    Wang, Hua; Dittmann, Lars

    2009-01-01

    . A two-level hierarchical scheduler is developed for the DRA module, which can provide more organized service differentiation among different service classes, and a measurement-based connection admission control strategy is introduced for the CAC module. Through system-level simulation, it is shown...... an important role in QoS provisioning for different types of services. In this chapter, we propose a downlink resource management framework for QoS scheduling in OFDMA based WiMAX systems. Our framework consists of a dynamic resource allocation (DRA) module and a connection admission control (CAC) module...

  12. Downlink resource management for QoS scheduling in IEEE 802.16 WiMAX networks

    DEFF Research Database (Denmark)

    Wang, Hua; Dittmann, Lars

    2010-01-01

    -level hierarchical scheduler is developed for the DRA module, which can provide more organized service differentiation among different service classes, and a measurement-based connection admission control strategy is introduced for the CAC module. Through system-level simulation, it is shown that the proposed...... an important role in QoS provisioning for different types of services. In this paper, we propose a downlink resource management framework for QoS scheduling in OFDMA based WiMAX systems. Our framework consists of a dynamic resource allocation (DRA) module and a connection admission control (CAC) module. A two...

  13. Wifi, WiMax and LTE multi-hop mesh networks basic communication protocols and application areas

    CERN Document Server

    Wei, Hung-Yu; Dixit, Sudhir

    2013-01-01

    Wifi, WiMAX, and Cellular Multihop Networks presents an overview of WiFi-based and WiMAX-based multihop relay networks. As the first text to cover IEEE 802.16j multihop hop relay technology, this revolutionary resource explores the latest advances in multi-hop and ad-hoc networking. Not only does this reference provide the technological aspects, but also the applications for the emerging technology and architectural issues. Ranging from introductory material to advanced topics, this guidebook, plus PowerPoint slides, is essential for engineers, researchers, and students interested in

  14. RLAM: A Dynamic and Efficient Reinforcement Learning-Based Adaptive Mapping Scheme in Mobile WiMAX Networks

    Directory of Open Access Journals (Sweden)

    M. Louta

    2014-01-01

    Full Text Available WiMAX (Worldwide Interoperability for Microwave Access constitutes a candidate networking technology towards the 4G vision realization. By adopting the Orthogonal Frequency Division Multiple Access (OFDMA technique, the latest IEEE 802.16x amendments manage to provide QoS-aware access services with full mobility support. A number of interesting scheduling and mapping schemes have been proposed in research literature. However, they neglect a considerable asset of the OFDMA-based wireless systems: the dynamic adjustment of the downlink-to-uplink width ratio. In order to fully exploit the supported mobile WiMAX features, we design, develop, and evaluate a rigorous adaptive model, which inherits its main aspects from the reinforcement learning field. The model proposed endeavours to efficiently determine the downlink-to-uplinkwidth ratio, on a frame-by-frame basis, taking into account both the downlink and uplink traffic in the Base Station (BS. Extensive evaluation results indicate that the model proposed succeeds in providing quite accurate estimations, keeping the average error rate below 15% with respect to the optimal sub-frame configurations. Additionally, it presents improved performance compared to other learning methods (e.g., learning automata and notable improvements compared to static schemes that maintain a fixed predefined ratio in terms of service ratio and resource utilization.

  15. Millimeter-wave wireless links for 5G mobile networks

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    Microwave photonics and radio-over-fiber (RoF) technologies have been investigated for over 20 years, leadingto a substantial stock of know-how which is now about to be exploited in the development of the 5th generationmobile systems (5G). These technologies have proven mature in niche areas...

  16. Evaluasi Kinerja Layanan IPTV pada Jaringan Testbed WiMAX Berbasis Standar IEEE 802.16-2004

    Directory of Open Access Journals (Sweden)

    Prasetiyono Hari Mukti

    2015-09-01

    Full Text Available In this paper, a performance evaluation for IPTV Services over WiMAX testbed based on IEEE Standard 802.16-2004 will be described. The performance of the proposed system is evaluated in terms of delay, jitter, throughput and packet loss. Service performance evaluations are conducted on network topology of point-to-point in the variation of background traffic with different scheduling types. Background traffic is injected into the system to give the sense that the proposed system has variation traffic load. Scheduling type which are used in this paper are Best Effort (BE, Non-Real-Time Polling Service (nrtPS, Real-Time Polling Service (rtPS and Unsolicited Grant Service (UGS. The expemerintal results of IPTV service performance over the testbed network show that the maximum average of delay, jitter, packet loss and jitter are 16.581 ms, 58.515 ms, 0.67 Mbps dan 10.96%, respectively.

  17. Performance Analysis of Wavelet Channel Coding in COST207-based Channel Models on Simulated Radio-over-Fiber Systems at the W-Band

    DEFF Research Database (Denmark)

    Cavalcante, Lucas Costa Pereira; Silveira, Luiz F. Q.; Rommel, Simon

    2016-01-01

    , such systems use diversity schemes in combination with digital signal processing (DSP) techniques to overcome effects such as fading and inter-symbol interference (ISI). Wavelet Channel Coding (WCC) has emerged as a technique to minimize the fading effects of wireless channels, which is a mayor challenge...

  18. Optical response of a d-fiber antenna in a finite-element analysis intended for radio-over-fiber applications.

    Science.gov (United States)

    Bhatti, A; Al-Raweshidy, H S; Murtaza, G

    2000-07-20

    An all-fiber antenna with a piezoelectric polymer-coated circular-core D fiber has been characterized by finite-element analysis. The response of the D-fiber antenna was determined over a wide frequency range from 1 to 500 MHz. The modeling predicts an electric-field-induced phase shift of 2.43 x 10(-5) rad/(V/m)/m at 5 MHz. At frequencies higher than 8 MHz the optical response is dominated by radial resonances of the D-fiber-coating composite. From the simulation results a minimum detectable electric field of 41-muV/m has been achieved with a 1-km length of coated D fiber. In addition, a D-fiber antenna network intended for microcellular communications has been analyzed by shot-noise-limited detection.

  19. An orthogonal wavelet division multiple-access processor architecture for LTE-advanced wireless/radio-over-fiber systems over heterogeneous networks

    Science.gov (United States)

    Mahapatra, Chinmaya; Leung, Victor CM; Stouraitis, Thanos

    2014-12-01

    The increase in internet traffic, number of users, and availability of mobile devices poses a challenge to wireless technologies. In long-term evolution (LTE) advanced system, heterogeneous networks (HetNet) using centralized coordinated multipoint (CoMP) transmitting radio over optical fibers (LTE A-ROF) have provided a feasible way of satisfying user demands. In this paper, an orthogonal wavelet division multiple-access (OWDMA) processor architecture is proposed, which is shown to be better suited to LTE advanced systems as compared to orthogonal frequency division multiple access (OFDMA) as in LTE systems 3GPP rel.8 (3GPP, http://www.3gpp.org/DynaReport/36300.htm). ROF systems are a viable alternative to satisfy large data demands; hence, the performance in ROF systems is also evaluated. To validate the architecture, the circuit is designed and synthesized on a Xilinx vertex-6 field-programmable gate array (FPGA). The synthesis results show that the circuit performs with a clock period as short as 7.036 ns (i.e., a maximum clock frequency of 142.13 MHz) for transform size of 512. A pipelined version of the architecture reduces the power consumption by approximately 89%. We compare our architecture with similar available architectures for resource utilization and timing and provide performance comparison with OFDMA systems for various quality metrics of communication systems. The OWDMA architecture is found to perform better than OFDMA for bit error rate (BER) performance versus signal-to-noise ratio (SNR) in wireless channel as well as ROF media. It also gives higher throughput and mitigates the bad effect of peak-to-average-power ratio (PAPR).

  20. Broadband photonic single sideband frequency up-converter based on the cross polarization modulation effect in a semiconductor optical amplifier for radio-over-fiber systems.

    Science.gov (United States)

    Lee, Seung-Hun; Kim, Hyoung-Jun; Song, Jong-In

    2014-01-13

    A broadband photonic single sideband (SSB) frequency up-converter based on the cross polarization modulation (XPolM) effect in a semiconductor optical amplifier (SOA) is proposed and experimentally demonstrated. An optical radio frequency (RF) signal in the form of an optical single sideband (OSSB) is generated by the photonic SSB frequency up-converter to solve the power fading problem caused by fiber chromatic dispersion. The generated OSSB RF signal has almost identical optical carrier power and optical sideband power. This SSB frequency up-conversion scheme shows an almost flat electrical RF power response as a function of the RF frequency in a range from 31 GHz to 75 GHz after 40 km single mode fiber (SMF) transmission. The photonic SSB frequency up-conversion technique shows negligible phase noise degradation. The phase noise of the up-converted RF signal at 49 GHz for an offset of 10 kHz is -93.17 dBc/Hz. Linearity analysis shows that the photonic SSB frequency up-converter has a spurious free dynamic range (SFDR) value of 79.51 dB · Hz(2/3).

  1. An all-optical frequency up-converter utilizing four-wave mixing in a semiconductor optical amplifier for sub-carrier multiplexed radio-over-fiber applications.

    Science.gov (United States)

    Kim, Hyoung-Jun; Song, Jong-In; Song, Ho-Jin

    2007-03-19

    A novel all-optical frequency up-converter utilizing four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) was proposed and experimentally demonstrated. The frequency up-converter converted an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) to an optical radio frequency (RF) signal (f(RF) = 35 and 40 GHz) through mixing with an optical local oscillator (LO) signal (f(LO) = 37.5 GHz). The up-converter showed positive conversion efficiency of 5.77 dB for the optical IF power of -22 dBm and the optical LO power of -13 dBm. This scheme showed broad bandwidths with respect to both LO and IF frequencies. The up-converter showed a phase noise of -84.5 dBc/Hz for the LO frequency of 37.5 GHz (f(LO)) and the offset frequency of 10 kHz after the frequency up-conversion.

  2. Bandwidth enhancement of electromagnetic coupled nonuniform H-shaped microstrip patch antenna for higher band of Wi-MAX applications

    Energy Technology Data Exchange (ETDEWEB)

    Bhardwaj, Dheeraj, E-mail: dbhardwaj.bit@gmail.com [Assistant Professor, Department of Physics, BIT-Mesra-Jaipur Campus, Jaipur 302017 (India); Gulati, Gitansh, E-mail: gitanshgulati@gmail.com [Bachelor of Engineering-ECE, BIT-Mesra-Jaipur Campus, Jaipur 302017 (India); Saraswat, Srishti, E-mail: saraswat.srishti@yahoo.in [Bachelor of Engineering-VII Sem, ECE, BIT-Mesra-Jaipur Campus, Jaipur 302017 (India); Sharma, Komal, E-mail: kbhardwaj18@gmail.com [Reader, Department of Physics, Swami Keshvanand Institute of Technology, Jaipur 302017 (India)

    2016-03-09

    The bandwidth enhancement of a stacked non-uniform electromagnetically coupled H-shaped Microstrip Antenna (SNHMA) with tapered edges is analyzed and simulated using the IE3D simulator. The proposed antenna prototype is drafted on FR-4 material and stacked further with an air discontinuity of 0.3 mm to the next layer. The various parameters optimized to achieve the best performance from the modified SNHMA primarily include a)length b)width of the patch c)air gap thickness. The redesigned antenna serves at two distinct frequencies with an elevated bandwidth of 30.85 % at the central frequency 5.762 GHz, approximately four times the bandwidth of the standard patch having the same dimensions. The simulated radiation patterns (E-plane and H-plane) are exhibited within the range of frequencies where the broadband response is observed. The specifications of the proposed structure make it promising for the higher band of Wi-MAX applications.

  3. Feasibility Study and Experimental Verification of Simplified Fiber-Supported 60-GHz Picocell Mobile Backhaul Links

    DEFF Research Database (Denmark)

    Lebedev, Alexander; Pang, Xiaodan; Vegas Olmos, Juan José

    2013-01-01

    analysis and comparison with an alternative E-band (60–90 GHz) technology. The 60-GHz fiber-wireless-fiber setup is then introduced: two spans of up to 20 km of optical fiber are deployed and bridged by up to 4 m of wireless distance. The 60-GHz radio-over-fiber technology is utilized in the first span...

  4. Implementation of a Smart Antenna Base Station for Mobile WiMAX Based on OFDMA

    Directory of Open Access Journals (Sweden)

    Seungheon Hyeon

    2009-01-01

    Full Text Available We present an implementation of a mobile-WiMAX (m-WiMAX base station (BS that supports smart antenna (SA functionality. To implement the m-WiMAX SA BS, we must address a number of key issues in baseband signal processing related to symbol-timing acquisition, the beamforming scheme, and accurate calibration. We propose appropriate solutions and implement an m-WiMAX SA BS accordingly. Experimental tests were performed to verify the validity of the solutions. Results showed a 3.5-time (5.5 dB link-budget enhancement on the uplink compared to a single antenna system. In addition, the experimental results were consistent with the results of the computer simulation.

  5. A Smart City Application: A Fully Controlled Street Lighting Isle Based on Raspberry-Pi Card, a ZigBee Sensor Network and WiMAX

    Directory of Open Access Journals (Sweden)

    Fabio Leccese

    2014-12-01

    Full Text Available A smart city application has been realized and tested. It is a fully remote controlled isle of lamp posts based on new technologies. It has been designed and organized in different hierarchical layers, which perform local activities to physically control the lamp posts and transmit information with another for remote control. Locally, each lamp post uses an electronic card for management and a ZigBee tlc network transmits data to a central control unit, which manages the whole isle. The central unit is realized with a Raspberry-Pi control card due to its good computing performance at very low price. Finally, a WiMAX connection was tested and used to remotely control the smart grid, thus overcoming the distance limitations of commercial Wi-Fi networks. The isle has been realized and tested for some months in the field.

  6. A Smart City Application: A Fully Controlled Street Lighting Isle Based on Raspberry-Pi Card, a ZigBee Sensor Network and WiMAX

    Science.gov (United States)

    Leccese, Fabio; Cagnetti, Marco; Trinca, Daniele

    2014-01-01

    A smart city application has been realized and tested. It is a fully remote controlled isle of lamp posts based on new technologies. It has been designed and organized in different hierarchical layers, which perform local activities to physically control the lamp posts and transmit information with another for remote control. Locally, each lamp post uses an electronic card for management and a ZigBee tlc network transmits data to a central control unit, which manages the whole isle. The central unit is realized with a Raspberry-Pi control card due to its good computing performance at very low price. Finally, a WiMAX connection was tested and used to remotely control the smart grid, thus overcoming the distance limitations of commercial Wi-Fi networks. The isle has been realized and tested for some months in the field. PMID:25529206

  7. A smart city application: a fully controlled street lighting isle based on Raspberry-Pi card, a ZigBee sensor network and WiMAX.

    Science.gov (United States)

    Leccese, Fabio; Cagnetti, Marco; Trinca, Daniele

    2014-12-18

    A smart city application has been realized and tested. It is a fully remote controlled isle of lamp posts based on new technologies. It has been designed and organized in different hierarchical layers, which perform local activities to physically control the lamp posts and transmit information with another for remote control. Locally, each lamp post uses an electronic card for management and a ZigBee tlc network transmits data to a central control unit, which manages the whole isle. The central unit is realized with a Raspberry-Pi control card due to its good computing performance at very low price. Finally, a WiMAX connection was tested and used to remotely control the smart grid, thus overcoming the distance limitations of commercial Wi-Fi networks. The isle has been realized and tested for some months in the field.

  8. Link budget analysis in the network designed mobile WiMAX technology in the territory of the urban area of the city of Gjakova

    OpenAIRE

    Shkelzen S. Nuza; Artan Z. Mazrekaj

    2012-01-01

    Wireless communication has now entered the second century of its use and has valuable merits of improving the quality of life of all mankind. Technologies for wireless and mobile communications replace each other every 2-3 years. The current version of the Protocol provides Internet access up to 40 Mbps and this version is expected to increase the bandwidth. The telecommunications sector is covered by three operators (Kujtesa, Ipko and PTK) and leaves much to be desired in improving service q...

  9. Converged delivery of WiMAX and wireline services over an extended reach passive optical access network

    DEFF Research Database (Denmark)

    Osadchiy, Alexey Vladimirovich; Prince, Kamau; Tafur Monroy, Idelfonso

    2010-01-01

    on a 2.4-GHz RF carrier over an 80-km long-reach access link at 100 Mb/s (down) and 64 Mb/s (up). Transmission of 64-QAM and 256-QAM-modulated signals on a 5.8-GHz RF carrier over a 118.8-km access link converged with four baseband differential quadrature phase shift keying (DQPSK) modulated wireline...

  10. A Triple-band Bandpass Filter using Tri-section Step-impedance and Capacitively Loaded Step-impedance Resonators for GSM, WiMAX, and WLAN systems

    Science.gov (United States)

    Chomtong, P.; Akkaraekthalin, P.

    2014-05-01

    This paper presents a triple-band bandpass filter for applications of GSM, WiMAX, and WLAN systems. The proposed filter comprises of the tri-section step-impedance and capacitively loaded step-impedance resonators, which are combined using the cross coupling technique. Additionally, tapered lines are used to connect at both ports of the filter in order to enhance matching for the tri-band resonant frequencies. The filter can operate at the resonant frequencies of 1.8 GHz, 3.7 GHz, and 5.5 GHz. At resonant frequencies, the measured values of S11 are -17.2 dB, -33.6 dB, and -17.9 dB, while the measured values of S21 are -2.23 dB, -2.98 dB, and -3.31 dB, respectively. Moreover, the presented filter has compact size compared with the conventional open-loop cross coupling triple band bandpass filters

  11. ANÁLISIS DE DESEMPEÑO DE CALIDAD DE SERVICIO SOBRE REDES INALÁMBRICAS BASADAS EN TECNOLOGÍA WIMAX

    Directory of Open Access Journals (Sweden)

    Ruben Dario Gomez Tovar

    2012-05-01

    Full Text Available Actualmente el uso de redes inalámbricas se encuentra en un punto de alta demanda, debido a su flexibilidad y bajos costos en la implementación de las mismas. A  partir de la construcción de la norma IEEE 802.16 (WiMAX  y de las necesidades actuales en campos médicos, educativos, entre otros por acceder a la información y en general por poder establecer comunicaciones confiables se permite que la industria y los centros de investigación fortalezcan la implementación de estas tecnologías.Para satisfacer estas necesidades se hace importante garantizar un servicio que cumpla con los requerimientos solicitados, en este orden de ideas es importante, analizar el funcionamiento de este tipo de tecnologías a través de la evaluación del desempeño incluyendo parámetros de calidad de servicio (QoS basados en la norma IEEE 802.16.

  12. Analysis of second order harmonic distortion due to transmitter non-linearity and chromatic and modal dispersion of optical OFDM SSB modulated signals in SMF-MMF fiber links

    Science.gov (United States)

    Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

    2017-01-01

    Single mode fibers (SMF) are typically used in Wide Area Networks (WAN), Metropolitan Area Networks (MAN) and also find applications in Radio over Fiber (RoF) architectures supporting data transmission in Fiber to the Home (FTTH), Remote Antenna Units (RAUs), in-building networks etc. Multi-mode fibers (MMFs) with low cost, ease of installation and low maintenance are predominantly (85-90%) deployed in-building networks providing data access in local area networks (LANs). The transmission of millimeter wave signals through the SMF in WAN and MAN, along with the reuse of MMF in-building networks will not levy fiber reinstallation cost. The transmission of the millimeter waves experiences signal impairments due to the transmitter non-linearity and modal dispersion of the MMF. The MMF exhibiting large modal dispersion limits the bandwidth-length product of the fiber. The second and higher-order harmonics present in the optical signal fall within the system bandwidth. This causes degradation in the received signal and an unwanted radiation of power at the RAU. The power of these harmonics is proportional to the non-linearity of the transmitter and the modal dispersion of the MMF and should be maintained below the standard values as per the international norms. In this paper, a mathematical model is developed for Second-order Harmonic Distortion (HD2) generated due to non-linearity of the transmitter and chromatic-modal dispersion of the SMF-MMF optic link. This is also verified using a software simulation. The model consists of a Mach Zehnder Modulator (MZM) that generates two m-QAM OFDM Single Sideband (SSB) signals based on phase shift of the hybrid coupler (90° and 120°). Our results show that the SSB signal with 120° hybrid coupler has suppresses the higher-order harmonics and makes the system more robust against the HD2 in the SMF-MMF optic link.

  13. The link in Linking

    Science.gov (United States)

    Caldwell, Jane C; Chiale, Pablo A; Gonzalez, Mario D; Baranchuk, Adrian

    2013-01-01

    We present 2 cases of the slow-fast form of AVNRT with initially narrow QRS complexes followed by sudden unexpected transition to persistently wide QRS complexes due to aberrant intraventricular conduction. Introduction of a properly timed extrastimulus in one case and critical oscillations in cycle length due to short-long coupling in the second case set the stage for the initial bundle branch block. However, persistence of the aberrancy pattern once the initial event abated was maintained by the "linking" phenomenon. Delayed, retrograde concealed activation from the contralateral bundle branch perpetuated the initial bundle branch block. PMID:23840106

  14. Variable Delay With Directly-Modulated R-SOA and Optical Filters for Adaptive Antenna Radio-Fiber Access

    DEFF Research Database (Denmark)

    Prince, Kamau; Presi, Marco; Chiuchiarelli, Andrea

    2009-01-01

    We present an all-optical adaptive-antenna radio over fiber transport system that uses proven, commercially-available components to effectively deliver standard-compliant optical signaling to adaptive multiantenna arrays for current and emerging radio technology implementations. The system is based...... types of signals defined in IEEE 802.16 (WiMAX) standard for wireless networks: a 90 Mbps single-carrier signal (64-QAM at 2.4 GHz) and a 78 Mbps multitone orthogonal frequency-division multiple access (OFDMA) signal. The power budget of this configuration supports a 4-element antenna array....

  15. Linked Partitions and Linked Cycles

    OpenAIRE

    Chen, William Y. C.; Wu, Susan Y. J.; Yan, Catherine H.

    2006-01-01

    The notion of noncrossing linked partition arose from the study of certain transforms in free probability theory. It is known that the number of noncrossing linked partitions of [n+1] is equal to the n-th large Schroder number $r_n$, which counts the number of Schroder paths. In this paper we give a bijective proof of this result. Then we introduce the structures of linked partitions and linked cycles. We present various combinatorial properties of noncrossing linked partitions, linked partit...

  16. Scandinavian links

    DEFF Research Database (Denmark)

    Matthiessen, Christian Wichmann; Knowles, Richard D.

    2014-01-01

    The European Round Table of Industrialists identified in the 1980ies 14 missing links in the transportation network of the continent. Three of them were found around the Danish island of Zealand. One link is within the nation, the other two are between nations. One link connects heavy economic....... They concentrate traffic flows and create strong transport corridors. They are the basis of new regional development regimes. “Ferries connect systems, fixed links unite systems”....

  17. Operative Links

    DEFF Research Database (Denmark)

    Wistoft, Karen; Højlund, Holger

    2012-01-01

    educational goals, learning content, or value clarification. Health pedagogy is often a matter of retrospective rationalization rather than the starting point of planning. Health and risk behaviour approaches override health educational approaches. Conclusions: Operational links between health education......, health professionalism, and management strategies pose the foremost challenge. Operational links indicates cooperative levels that facilitate a creative and innovative effort across traditional professional boundaries. It is proposed that such links are supported by network structures, shared semantics...

  18. MIMO-OFDM WDM PON with DM-VCSEL for femtocells application

    DEFF Research Database (Denmark)

    Binti Othman, Maisara; Deng, Lei; Pang, Xiaodan

    2011-01-01

    We report on experimental demonstration of 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20 km WDM-PON with directly modulated (DM) VCSELs for femtocells application. MIMO-OFDM algorithms effectively compensate for impairments in the wireless link. Error-free signal demodulation of 64...

  19. Gigabit close-proximity wireless connections supported by 60 GHz RoF links with low carrier suppression

    DEFF Research Database (Denmark)

    Lebedev, Alexander; Pang, Xiaodan; Vegas Olmos, Juan José

    2013-01-01

    We present an experimental investigation of the 60 GHz optical carrier suppressed radio over fiber systems with less than 5 dB carrier suppression. As a case study, the 60 GHz RoF signal is generated using a 12.5 Gb/s commercially available Mach-Zehnder modulator biased at its minimum point. We r...... with simplified techniques of lightwave generation, baseband data modulation, and RF downconversion might be a promising enabling technology for fiber support of close-proximity wireless terminals....

  20. Linked data

    NARCIS (Netherlands)

    Koster, L.

    2011-01-01

    Semantisch web, linked data, web 3.0… Het zijn allemaal termen die vaak door elkaar worden gebruikt. Onterecht vindt Lukas Koster van de Universiteit van Amsterdam. Wat houden die begrippen nu eigenlijk in?

  1. Link Analysis

    Science.gov (United States)

    Donoho, Steve

    Link analysis is a collection of techniques that operate on data that can be represented as nodes and links. This chapter surveys a variety of techniques including subgraph matching, finding cliques and K-plexes, maximizing spread of influence, visualization, finding hubs and authorities, and combining with traditional techniques (classification, clustering, etc). It also surveys applications including social network analysis, viral marketing, Internet search, fraud detection, and crime prevention.

  2. Análise da eficiência espectral para bandas licenciadas WiMAX considerando a duplexação e o perfil de tráfego

    Directory of Open Access Journals (Sweden)

    Márcia Maria Savoine

    2012-11-01

    Full Text Available Este trabalho apresenta a comparação efetuada por meio de simulações de eventos discretos, realizadas com o software ARENA, das técnicas de Duplexação por Divisão no Tempo (TDD e Duplexação por Divisão da Freqüência (FDD, técnicas presentes no padrão IEEE 802.16 e utilizadas pelo WiMAX nos canais bidirecionais de uplink e downlink. O modelo de simulação considerou na fila de chegada dos serviços o conceito FIFO e as simulações foram realizadas considerando cinco aplicações (Streaming, Download, Web, E-mail e Small-Transaction para downlink e uplink. O parâmetro de eficiência considerado foi o número mínimo de canais necessário em cada um dos canais padrões. A análise efetuada permitiu identificar, dada estas condições de tráfego, qual das técnicas seria a mais indicada. Constatou-se ainda que em tráfego de dados assimétricos a técnica TDD se apresentou mais eficiente e, observou-se existir ociosidade de espectro na técnica FDD.

  3. Dancing links

    OpenAIRE

    Knuth, Donald E.

    2000-01-01

    The author presents two tricks to accelerate depth-first search algorithms for a class of combinatorial puzzle problems, such as tiling a tray by a fixed set of polyominoes. The first trick is to implement each assumption of the search with reversible local operations on doubly linked lists. By this trick, every step of the search affects the data incrementally. The second trick is to add a ghost square that represents the identity of each polyomino. Thus puts the rule that each polyomino be ...

  4. Sex-linked recessive

    Science.gov (United States)

    Inheritance - sex-linked recessive; Genetics - sex-linked recessive; X-linked recessive ... X-linked recessive diseases most often occur in males. Males have only one X chromosome. A single recessive gene ...

  5. Sex-linked dominant

    Science.gov (United States)

    Inheritance - sex-linked dominant; Genetics - sex-linked dominant; X-linked dominant; Y-linked dominant ... can be either an autosomal chromosome or a sex chromosome. It also depends on whether the trait ...

  6. Linked alternating forms and linked symplectic Grassmannians

    OpenAIRE

    Osserman, Brian; Bigas, Montserrat Teixidor I.

    2011-01-01

    Motivated by applications to higher-rank Brill-Noether theory and the Bertram-Feinberg-Mukai conjecture, we introduce the concepts of linked alternating and linked symplectic forms on a chain of vector bundles, and show that the linked symplectic Grassmannians parametrizing chains of subbundles isotropic for a given linked symplectic form has good dimensional behavior analogous to that of the classical symplectic Grassmannian.

  7. Linked data management

    CERN Document Server

    Hose, Katja; Schenkel, Ralf

    2014-01-01

    Linked Data Management presents techniques for querying and managing Linked Data that is available on today’s Web. The book shows how the abundance of Linked Data can serve as fertile ground for research and commercial applications. The text focuses on aspects of managing large-scale collections of Linked Data. It offers a detailed introduction to Linked Data and related standards, including the main principles distinguishing Linked Data from standard database technology. Chapters also describe how to generate links between datasets and explain the overall architecture of data integration systems based on Linked Data. A large part of the text is devoted to query processing in different setups. After presenting methods to publish relational data as Linked Data and efficient centralized processing, the book explores lookup-based, distributed, and parallel solutions. It then addresses advanced topics, such as reasoning, and discusses work related to read-write Linked Data for system interoperation. Desp...

  8. Experimental investigation of inter-core crosstalk tolerance of MIMO-OFDM/OQAM radio over multicore fiber system.

    Science.gov (United States)

    He, Jiale; Li, Borui; Deng, Lei; Tang, Ming; Gan, Lin; Fu, Songnian; Shum, Perry Ping; Liu, Deming

    2016-06-13

    In this paper, the feasibility of space division multiplexing for optical wireless fronthaul systems is experimentally demonstrated by implementing high speed MIMO-OFDM/OQAM radio signals over 20km 7-core fiber and 0.4m wireless link. Moreover, the impact of optical inter-core crosstalk in multicore fibers on the proposed MIMO-OFDM/OQAM radio over fiber system is experimentally evaluated in both SISO and MIMO configurations for comparison. The experimental results show that the inter-core crosstalk tolerance of the proposed radio over fiber system can be relaxed to -10 dB by using the proposed MIMO-OFDM/OQAM processing. These results could guide high density multicore fiber design to support a large number of antenna modules and a higher density of radio-access points for potential applications in 5G cellular system.

  9. Linked Station Neighbors

    Data.gov (United States)

    Federal Communications Commission — This file that is a subset of the Linked-Station Set file. This file specifies, for each U.S. or impeding Canadian station part of a linked station set, the set of...

  10. Visualisierung von typisierten Links in Linked Data

    Directory of Open Access Journals (Sweden)

    Georg Neubauer

    2017-09-01

    Full Text Available Das Themengebiet der Arbeit behandelt Visualisierungen von typisierten Links in Linked Data. Die wissenschaftlichen Gebiete, die im Allgemeinen den Inhalt des Beitrags abgrenzen, sind das Semantic Web, das Web of Data und Informationsvisualisierung. Das Semantic Web, das von Tim Berners Lee 2001 erfunden wurde, stellt eine Erweiterung zum World Wide Web (Web 2.0 dar. Aktuelle Forschungen beziehen sich auf die Verknüpfbarkeit von Informationen im World Wide Web. Um es zu ermöglichen, solche Verbindungen wahrnehmen und verarbeiten zu können sind Visualisierungen die wichtigsten Anforderungen als Hauptteil der Datenverarbeitung. Im Zusammenhang mit dem Sematic Web werden Repräsentationen von zuhammenhängenden Informationen anhand von Graphen gehandhabt. Der Grund des Entstehens dieser Arbeit ist in erster Linie die Beschreibung der Gestaltung von Linked Data-Visualisierungskonzepten, deren Prinzipien im Rahmen einer theoretischen Annäherung eingeführt werden. Anhand des Kontexts führt eine schrittweise Erweiterung der Informationen mit dem Ziel, praktische Richtlinien anzubieten, zur Vernetzung dieser ausgearbeiteten Gestaltungsrichtlinien. Indem die Entwürfe zweier alternativer Visualisierungen einer standardisierten Webapplikation beschrieben werden, die Linked Data als Netzwerk visualisiert, konnte ein Test durchgeführt werden, der deren Kompatibilität zum Inhalt hatte. Der praktische Teil behandelt daher die Designphase, die Resultate, und zukünftige Anforderungen des Projektes, die durch die Testung ausgearbeitet wurden.

  11. Linking open vocabularies

    CERN Document Server

    Greifender, Elke; Seadle, Michael

    2013-01-01

    Linked Data (LD), Linked Open Data (LOD) and generating a web of data, present the new knowledge sharing frontier. In a philosophical context, LD is an evolving environment that reflects humankinds' desire to understand the world by drawing on the latest technologies and capabilities of the time. LD, while seemingly a new phenomenon did not emerge overnight; rather it represents the natural progression by which knowledge structures are developed, used, and shared. Linked Open Vocabularies is a significant trajectory of LD. Linked Open Vocabularies targets vocabularies that have traditionally b

  12. Let's "Downscale" Linked Data

    NARCIS (Netherlands)

    Gueret, C.D.M.; de Boer, V.; Schlobach, K.S.

    2014-01-01

    Open data policies and linked data publication are powerful tools for increasing transparency, participatory governance, and accountability. The linked data community proudly emphasizes the economic and societal impact such technology shows. But a closer look proves that the design and deployment of

  13. Let's "Downscale" Linked Data

    NARCIS (Netherlands)

    Gueret, Christophe; de Boer, Victor; Schlobach, Stefan

    2014-01-01

    Open data policies and linked data publication are powerful tools for increasing transparency, participatory governance, and accountability. A closer look at linked data technologies, however, proves that their design and deployment exclude the majority of the world’s population. It will take small

  14. Broken Links Tools

    Science.gov (United States)

    Some of these tools can be used on Drupal pages that are not published yet, or on non-Drupal content. Some, such as the Bookmarklet tools, can help make checking and correcting your links easier when used alongside Drupal's link reports.

  15. Refined Hopf Link Revisited

    CERN Document Server

    Iqbal, Amer

    2012-01-01

    We establish a relation between the refined Hopf link invariant and the S-matrix of the refined Chern-Simons theory. We show that the refined open string partition function corresponding to the Hopf link, calculated using the refined topological vertex, when expressed in the basis of Macdonald polynomials gives the S-matrix of the refined Chern-Simons theory.

  16. Link to paper

    Data.gov (United States)

    U.S. Environmental Protection Agency — Link to the paper. This dataset is associated with the following publication: Naile, J., A.W. Garrison, J. Avants, and J. Washington. Isomers/enantiomers of...

  17. Introduction to Reference Links

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Unlike most traditional metadata systems, the power of ServCat comes in relating a Reference to others. This module discusses the different types of links (aka...

  18. Link prediction on Twitter

    National Research Council Canada - National Science Library

    Sanda Martinčić-Ipšić; Edvin Močibob; Matjaž Perc

    2017-01-01

    .... Open access to information on Twitter makes it a valuable source of data for research on social interactions, sentiment analysis, content diffusion, link prediction, and the dynamics behind human...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Education Projects » Learn the Link - Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter ... research findings and news updates. Read on to Learn the Link between drug use and HIV and ...

  20. enzyme-linked

    African Journals Online (AJOL)

    SA MEDIESE TYDSKRIF DEEL 63 29 JANUARIE 1983. B surface antigen in donated screening and confirmation by immunosorbent assay. Hepatitis blood - enzyme-linked. M. O. BUBB, T. ... weeks at weekly intervals. After 6 weeks test blood samples were ... This assay normally takes 3 hours. Results. Fig. 1. Frequency ...

  1. Response model parameter linking

    NARCIS (Netherlands)

    Barrett, M.L.D.

    2015-01-01

    With a few exceptions, the problem of linking item response model parameters from different item calibrations has been conceptualized as an instance of the problem of equating observed scores on different test forms. This thesis argues, however, that the use of item response models does not require

  2. Australian Curriculum Linked Lessons

    Science.gov (United States)

    Hurrell, Derek; O'Neil, Jennifer

    2011-01-01

    In providing a continued focus on tasks and activities that help to illustrate key ideas embedded in the new Australian Curriculum, this issue the authors focus, on Geometry in the Measurement and Geometry strand with strong links for an integrated focus on the Statistics and Probability strand. The small unit of work on the sorting and…

  3. Linking Literacy and Movement

    Science.gov (United States)

    Pica, Rae

    2010-01-01

    There are many links between literacy and movement. Movement and language are both forms of communication and self-expression. Rhythm is an essential component of both language and movement. While people may think of rhythm primarily in musical terms, there is a rhythm to words and sentences as well. Individuals develop an internal rhythm when…

  4. Linking place and mind

    DEFF Research Database (Denmark)

    Jensen, Marie Møller

    2016-01-01

    This paper investigates the salience of vernacular Tyneside forms on the basis of theories of enregisterment and exemplar processing. On one level, exemplar theory provides a psycholinguistic account of how the link between social value and linguistic features is possible. Conversely, integrating...

  5. TWSTFT Link Calibration Report

    Science.gov (United States)

    2015-09-01

    Washington Headquarters Services , Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302...and Bauch A (2014) THE EUROPEAN TW CALIBRATION CAMPAIGN 2014 IN THE SCOPE OF GALILEO (TGVF- FOC), An opportunity to update, TW link calibrations in

  6. Isolated Tracklet Linking

    Science.gov (United States)

    Weryk, Robert J.; Wainscoat, Richard J.; Williams, Gareth

    2017-10-01

    We discuss our on-going work to reduce the size of the Isolated Tracklet File (ITF) : a database hosted by the Minor Planet Center (MPC) containing 14+ million unlinked detections of asteroids. The ITF is dominated by observations from Pan-STARRS1 (F51), the Catalina Sky Survey (G96), and the Spacewatch Project (691).Survey telescopes are dependent on the follow-up capabilities of other telescopes, but many of their detected objects are not linked to already known objects, are are either not posted to the NEO Confirmation Page and/or are not followed up sufficiently, and therefore have their astrometry relegated to the ITF. While many of these asteroids may have in fact been previously observed sufficiently over longer timescales (enough to become designated objects), the linking of their astrometry can pose a challenge.We have developed a search method capable of finding and linking these isolated detections for distinct types of orbit classes, including main-belt and Hungaria objects (which often appear on the NEOCP due to their apparent motion). We use a brute-force technique which compares tracklets having motion which suggests they are the same object. Suspected linkages are further tested by searching for additional tracklets over multiple oppositions.So far, we have linked a significant portion of the ITF and have submitted these linkages to the MPC. We are confident in being able to link even more tracklets. Our method can even associate these new linkages with already designated objects, which will eventually lead to them becoming numbered objects. We hope to improve the efficiency of all asteroid surveys as future detections can be batch submitted without manual review, and more objects which are well known will not be posted to the NEOCP.

  7. What is a virtual link?

    OpenAIRE

    Kuperberg, Greg

    2002-01-01

    Several authors have recently studied virtual knots and links because they admit invariants arising from R-matrices. We prove that every virtual link is uniquely represented by a link L in S X I, a thickened, compact, oriented surface S, such that the link complement (S X I) - L has no essential vertical cylinder.

  8. Bottom-linked innovation

    DEFF Research Database (Denmark)

    Kristensen, Catharina Juul

    2018-01-01

    Employee-driven innovation is gaining ground as a strategy for developing sustainable organisations in the public and private sector. This type of innovation is characterised by active employee participation, and the bottom-up perspective is often emphasised. This article explores an issue that has...... hitherto been paid little explicit attention, namely collaboration between middle managers and employees in innovation processes. In contrast to most studies, middle managers and employees are here both subjects of explicit investigation. The collaboration processes explored in this article are termed...... ‘bottom-linked innovation’. The empirical analysis is based on an in-depth qualitative study of bottom-linked innovation in a public frontline institution in Denmark. By combining research on employee-driven innovation and middle management, the article offers new insights into such collaborative...

  9. Linking assumptions in amblyopia

    Science.gov (United States)

    LEVI, DENNIS M.

    2017-01-01

    Over the last 35 years or so, there has been substantial progress in revealing and characterizing the many interesting and sometimes mysterious sensory abnormalities that accompany amblyopia. A goal of many of the studies has been to try to make the link between the sensory losses and the underlying neural losses, resulting in several hypotheses about the site, nature, and cause of amblyopia. This article reviews some of these hypotheses, and the assumptions that link the sensory losses to specific physiological alterations in the brain. Despite intensive study, it turns out to be quite difficult to make a simple linking hypothesis, at least at the level of single neurons, and the locus of the sensory loss remains elusive. It is now clear that the simplest notion—that reduced contrast sensitivity of neurons in cortical area V1 explains the reduction in contrast sensitivity—is too simplistic. Considerations of noise, noise correlations, pooling, and the weighting of information also play a critically important role in making perceptual decisions, and our current models of amblyopia do not adequately take these into account. Indeed, although the reduction of contrast sensitivity is generally considered to reflect “early” neural changes, it seems plausible that it reflects changes at many stages of visual processing. PMID:23879956

  10. Overseas links as export conduits

    OpenAIRE

    Hanley, Aoife

    2009-01-01

    This paper investigates the relationship between exports and overseas links using data from the UK Community Innovation Survey. Overseas vertical and horizontal links are associated with an average increase in export intensity of 74 and 156 percent for vertical and horizontal overseas links respectively. Firm size shows no significant interactions with overseas links. The data suggests that overseas links are a relatively infrequent form of conducting trade. My findings support the role of Go...

  11. LinkEdu

    OpenAIRE

    Gómez Dios, Albert

    2015-01-01

    The aim is to develop an application LinkEdu that will keep families connected schools. To carry out this project first developed a web application where www.linkedu.tk have access to the schools and teachers and where they can keep data centers, courses, subjects and other important data the students of school. Furthermore develops a mobile applications messaging standards that allow communication with a particular tutor his son. L'objectiu d'aquest projecte és el desenvolupament d'una ap...

  12. EEE Links. Volume 5

    Science.gov (United States)

    Humphrey, Robert (Editor)

    1999-01-01

    The EEE Links Newsletter is a quarterly publication produced by Code 562 in support of the NASA HQ funded NASA Electronic Parts and Packaging (NEPP) Program. The newsletter is produced as an electronic format deliverable made available via the referenced www site administered by Code 562, The newsletter publishes brief articles on topics of interest to NASA programs and projects in the area of electronic parts and packaging. The newsletter does not provide information pertaining to patented or proprietary information. The information provided is at the level of that produced by industry and university researchers and is published at national and international conferences.

  13. Linking consumer experiences

    DEFF Research Database (Denmark)

    Smed, Karina Madsen

    Consumers consume products in various ways serving a number of purposes. Much attention has been paid to experiences attached to consumption, sometimes very explicitly, e.g. in tourism, the essence of which is experiences of various sorts, but often also implicitly as internalised experiences...... become part of the individual self, worldview, and behaviour. This paper seeks to explore links between consumer experiences through the exploration of narrative sequences in travel blogs. Findings indicate that non-consumption is a central element to the bloggers and also indicative of a community...

  14. Knots and links

    CERN Document Server

    Rolfsen, Dale

    2003-01-01

    Rolfsen's beautiful book on knots and links can be read by anyone, from beginner to expert, who wants to learn about knot theory. Beginners with a basic background find an inviting introduction to the elements of topology, emphasizing the tools needed for understanding knots, the fundamental group and van Kampen's theorem, for example, which are then applied to concrete problems, such as computing knot groups. For experts, Rolfsen explains advanced topics, such as the connections between knot theory and surgery and how they are useful to understanding three-manifolds. Besides providing a guide

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the Link - Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors ... GA: CDC, DHHS. Retrieved June 2012 How are Drug Abuse and HIV Related? Drug abuse and addiction ...

  16. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the Link - Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors ... GA: CDC, DHHS. Retrieved November 2017. How are Drug Misuse and HIV Related? Drug misuse and addiction ...

  17. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Misuse and HIV Related? Drug misuse and addiction have been linked with HIV/AIDS since the beginning ... the link between drug misuse and HIV. We have produced a set of multicultural public service announcements ( ...

  18. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and the disease it causes (AIDS) are often linked and referred to as "HIV/AIDS." HIV can ... HIV Related? Drug misuse and addiction have been linked with HIV/AIDS since the beginning of the ...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the link between drug abuse and HIV infection. It contains information for young people, parents and teachers, ... present time. The virus (HIV) and the disease it causes (AIDS) are often linked and referred to ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Projects » Learn the Link - Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 – ... HIV and to help us Send the Message . Get the Facts What are HIV and AIDS? HIV ( ...

  1. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Plan Search Share Print Home » News & Events » Public Education Projects » Learn the Link - Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors associated with drug abuse ...

  2. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors associated with drug ... easily copy and paste to help show your support for Learn the Link . Be sure to check ...

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... send the message to young people and to parents, teachers, and the media about the link between drug ... Send the message to young people and to parents, teachers, and the media about the link between drug ...

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Projects » Learn the Link - Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 – ... and to help us Send the Message . Get the Facts What are HIV and AIDS? HIV (human ...

  5. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and to parents, teachers, and the media about the link between drug abuse and HIV. ...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and to parents, teachers, and the media about the link between drug misuse and HIV. ...

  7. Link Analysis for Space Communication Links Using ARQ Protocol

    Science.gov (United States)

    Cheung, Kar-Ming; Lau, Chi-Wung; Lee, Charles

    2014-01-01

    In space communications, standard link analysis assumes that messages are sent once. For a communication link that uses an error-correction coding scheme, bit-error-rate (BER) or frame-error-rate (FER), and link margins are common metrics that characterize the quality of a link, and they are used to determine the supportable data rate. With the advent of Automatic Repeat-reQuest (ARQ) protocols, when messages are corrupted during transmission, they can be resent multiple times automatically until they are correctly received and acknowledged. The concept of BER, FER, and link margin cannot be directly applied, and the link analysis approach for ARQ links needs to be re-examined.

  8. Linked Data: an Evolution

    Directory of Open Access Journals (Sweden)

    Karen Coyle

    2013-01-01

    Full Text Available Actually the world is full of hi-tech devices that allow in different ways to stay always connected and up-to-date. The high level of interactivity and interoperability is now a fundamental prerogative in the new millennium communication which no one can be exempted. In particular, librarian universe must reconfigure this new way to exchange and provide information otherwise it will cause the steady decline, and this will cause a huge loss of users who will find different ways to information: such as tablet or smartphone. The linked data can provide significant support for libraries to ensure that they can still be leaders in the future. A brief mention to the studies conducted in this domain.

  9. Linking specification to differentiation

    Science.gov (United States)

    zur Lage, Petra I; Simpson, T Ian

    2011-01-01

    Much of developmental biology is concerned with the processes by which cells become committed to particular fates in a regulated fashion, whereas cell biology addresses, among other things, the variety of differentiated forms and functions that cells can acquire. One open question is how the regulators of the former process lead to attainment of the latter. “High-level” regulators of cell fate specification include the proneural factors, which drive cells to commit as precursors in the sensory nervous system. Recent research has concentrated on the gene expression events downstream of proneural factor function. Here we summarize this research and describe our own research that has provided clear links between a proneural factor, atonal and the cell biological program of ciliogenesis, which is a central aspect of sensory neuron differentiation. PMID:21558799

  10. Named Entity Linking Algorithm

    Directory of Open Access Journals (Sweden)

    M. F. Panteleev

    2017-01-01

    Full Text Available In the tasks of processing text in natural language, Named Entity Linking (NEL represents the task to define and link some entity, which is found in the text, with some entity in the knowledge base (for example, Dbpedia. Currently, there is a diversity of approaches to solve this problem, but two main classes can be identified: graph-based approaches and machine learning-based ones. Graph and Machine Learning approaches-based algorithm is proposed accordingly to the stated assumptions about the interrelations of named entities in a sentence and in general.In the case of graph-based approaches, it is necessary to solve the problem of identifying an optimal set of the related entities according to some metric that characterizes the distance between these entities in a graph built on some knowledge base. Due to limitations in processing power, to solve this task directly is impossible. Therefore, its modification is proposed. Based on the algorithms of machine learning, an independent solution cannot be built due to small volumes of training datasets relevant to NEL task. However, their use can contribute to improving the quality of the algorithm. The adaptation of the Latent Dirichlet Allocation model is proposed in order to obtain a measure of the compatibility of attributes of various entities encountered in one context.The efficiency of the proposed algorithm was experimentally tested. A test dataset was independently generated. On its basis the performance of the model was compared using the proposed algorithm with the open source product DBpedia Spotlight, which solves the NEL problem.The mockup, based on the proposed algorithm, showed a low speed as compared to DBpedia Spotlight. However, the fact that it has shown higher accuracy, stipulates the prospects for work in this direction.The main directions of development were proposed in order to increase the accuracy of the system and its productivity.

  11. Too Many Links in the Horizon; What is Next? Linked Views and Linked History

    NARCIS (Netherlands)

    E. Liarou (Erietta); S. Idreos (Stratos)

    2011-01-01

    textabstractThe trend for more online linked data becomes stronger. Foreseeing a future where ``everything" will be online and linked, we ask the critical question; what is next? We envision that managing, querying and storing large amounts of links and data is far from yet another query

  12. Simplified Fiber-Wireless Distribution of HD Video in Passive and Active W-band Close Proximity Terminals

    DEFF Research Database (Denmark)

    Lebedev, Alexander; Rodes Lopez, Roberto; Yu, Xianbin

    2012-01-01

    We experimentally demonstrate uncompressed high-definition (HD) video distribution at 84 GHz Radio over Fiber link achieving up to 3 meters of wireless transmission. We experimentally emulate Metro-Access architecture by deploying single/multimode fibers. Passive and active approaches for remote...... antenna unit (RAU) are experimentally investigated. The bit error rate (BER) performance of the optical and wireless channels is reported. A successful transmission of uncompressed HD video in the W-band wireless channel is demonstrated with prospects to pave the way for application-focused fiber...

  13. Linking to the Future

    Science.gov (United States)

    Moore, John W.

    1999-09-01

    of JCE in the mail each month, and I expect you do too. I can glance at the cover to get an overview of an issue's content, and I usually am enticed inside by intriguing cover art. I can scan the table of contents to find articles I want to read, or I can just browse through the issue to see what looks interesting. Usually the editors have juxtaposed related articles so that I often find a small treasure trove. The printed Journal is quite portable and can be read in a car or airplane. It will last a long time, and until the paper deteriorates, I will never have a problem reading back issues. I have almost every issue from the first day I subscribed and have even added some older ones from collections of retired colleagues who no longer had shelf space for them. I certainly would not want to give up my printed copies, and I want to keep getting them. I find that JCE Online provides a different kind of resource that is equally valuable. It contains more information, and information that is more appropriate in electronic form. It links related ideas into a much more complex web of information than is possible in print. And it opens pathways to lots of information that is not part of JCE but resides elsewhere. Using this issue as an example, let's take a tour of what JCE Online can do. Point your Web browser to http://jchemed.chem.wisc.edu Click on Journal and then on Current Issue (unless September 1999 is no longer the current issue, in which case you will find it in Past Issues). In the table of contents, find the article "UV Catalysis, Cyanotype Photography, and Sunscreens". Click on the title. When the abstract appears, click on Full Text (PDF) to see the article, just as it appears on page 1199 in this issue. When you are prompted, enter the name and subscriber number from your address label. At the end of the article you will find that supplementary materials are available (including a procedure for testing sunscreens) and you can click on the link to view them

  14. Using ATM over SATCOM links

    Science.gov (United States)

    Comparetto, Gary M.

    1995-01-01

    The Asynchronous Transfer Mode (ATM) protocol is studied from the standpoint of determining what limitations, if any, exist in using it over satellite links. It is concluded that, while there is nothing intrinsic about ATM that would generally preclude its use over satellite links, there are, however, several intrinsic characteristics of satellite links, as well as some satellite system configuration-specific issues, that must be taken into account.

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... content En español Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter ...

  16. Multi-Criteria Vertical Handover Comparison between Wimax and Wifi

    Directory of Open Access Journals (Sweden)

    Maroua Drissi

    2015-07-01

    Full Text Available In next generation wireless networks, the most tempting feature is the ability of the user to move smoothly over different access networks regardless of the network access technology. In this paper we study the benefit of Multiple Attribute Decision Making (MADM strategies for network selection. We compare three of these methods naming Simple Additive Weighting (SAW, Multiplicative Exponential Weighting (MEW and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS in a realtime ns-3 simulation. Analytic Hierarchy Process (AHP provides the weights of attributes which allow the comparison in different types of applications. Therefore, we propose a performance evaluation model with a reconfiguration of AHP parameters used in the literature. Simulation results show that the proposed parameters provide an improvement of Delay and offer allowable Packet loss in different types of applications.

  17. Linking Wikipedia to the web

    NARCIS (Netherlands)

    Kaptein, R.; Serdyukov, P.; Kamps, J.; Chen, H.-H.; Efthimiadis, E.N.; Savoy, J.; Crestani, F.; Marchand-Maillet, S.

    2010-01-01

    We investigate the task of finding links from Wikipedia pages to external web pages. Such external links significantly extend the information in Wikipedia with information from the Web at large, while retaining the encyclopedic organization of Wikipedia. We use a language modeling approach to create

  18. Game Changer: Linked Learning Detroit

    Science.gov (United States)

    ConnectEd: The California Center for College and Career, 2016

    2016-01-01

    JP Morgan Chase joins the Skillman Foundation, the Ford Foundation, and the Ford Motor Company Fund, whose grants total $7 million and will connect 10,000 Detroit high school students to career education and work experiences over the next three years through Linked Learning Detroit. Learn about Linked Learning Detroit through interviews with…

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... your friends, colleagues, or other organizations in your tweets to spread the word even further. Tweet About Learn the Link To help send the ... to use the hashtag #LearntheLink. Need ideas for tweets? We’ve provided sample tweets that you can ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, we ...

  1. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Post on Facebook About Learn the Link Need ideas for posts? We’ve provided sample Facebook status ... be sure to use the hashtag #LearntheLink. Need ideas for tweets? We’ve provided sample tweets that ...

  2. [Sex-linked juvenile retinoschisis].

    Science.gov (United States)

    François, P; Turut, P; Soltysik, C; Hache, J C

    1976-02-01

    About 13 observations of sexe linked juvenile retinoschisis, the authors describe the ophthalmoscopic, fluorographic and functional aspects of the disease whose caracteristics are:--its sexe linked recessive heredity; --its clinical characterestics associating: a microcystic macular degeneration, peripheral retinal lesions, vitreous body alterations, --an electroretinogram of the negative type.

  3. Interpreting Linked Psychomotor Performance Scores

    Science.gov (United States)

    Looney, Marilyn A.

    2013-01-01

    Given that equating/linking applications are now appearing in kinesiology literature, this article provides an overview of the different types of linked test scores: equated, concordant, and predicted. It also addresses the different types of evidence required to determine whether the scores from two different field tests (measuring the same…

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... link between drug abuse and HIV. http://1.usa.gov/1z20ww6 How many of us think about ... can’t ignore. Learn the Link: http://1.usa.gov/1uSUAI3 Think you’re not at risk? ...

  5. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS ... risks and benefits when making decisions. This page connects you to information about the link between drug ...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse ... Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors associated with drug misuse are ...

  7. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse Commonly Abused Drugs Charts Emerging ... Badges Other Resources Strategic Plan Search Share Print Home » News & Events » Public Education Projects » Learn the Link - ...

  8. Hypermedia: The Link with Time

    NARCIS (Netherlands)

    L. Hardman (Lynda); J.R. van Ossenbruggen (Jacco); L. Rutledge (Lloyd); D.C.A. Bulterman (Dick)

    1999-01-01

    textabstractThis essay presents a brief discussion of combining temporal aspects of multimedia presentations with hypertext links. Three ways of combining linking with temporally synchronized components of a presentation are described. We describe work that has been done to incorporate both temporal

  9. Optimizing pointer linked data structures

    NARCIS (Netherlands)

    Holm, Carl Wilhelm Mattias

    2013-01-01

    The thesis explores different ways of optimizing pointer linked data structures, and especially restructuring them. The mechanisms are based on compiler technology, theory, computer languages and hardware architecture that are capable of optimizing the memory layout of complex pointer linked data

  10. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... link between drug misuse and HIV. http://1.usa.gov/1z20ww6 How many of us think about ... can’t ignore. Learn the Link: http://1.usa.gov/1uSUAI3 Think you’re not at risk? ...

  11. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs ... HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors associated with drug misuse ...

  12. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs ... HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors associated with drug abuse ...

  13. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and to parents, teachers, and the media about the link between drug ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Learn the Link campaign uses TV, print, and Web public service announcements (PSAs), as well as posters, e-cards, ... to misuse drugs. The Learn the Link public service campaign is just one ... this Web site. Sincerely, Nora D. Volkow, M.D. Director ...

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Plan Search Share Print Home » News & Events » Public Education Projects » Learn the Link - Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors associated with drug misuse are among the main factors in the spread of HIV infection in the ...

  16. LOTUS: Linked open text unleashed

    NARCIS (Netherlands)

    Ilievski, F.; Beek, Wouter; Van Erp, Marieke; Rietveld, Laurens; Schlobach, Stefan

    2015-01-01

    It is dificult to find resources on the Semantic Web today, in particular if one wants to search for resources based on natural language keywords and across multiple datasets. In this paper, we present LOTUS: Linked Open Text UnleaShed, a full-text lookup index over a huge Linked Open Data

  17. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... NIDA’s "Learn the Link" campaign continues to raise awareness among this generation of the real risks of ...

  18. Decouplink: Dynamic Links for Java

    DEFF Research Database (Denmark)

    Jensen, Martin Lykke Rytter; Jørgensen, Bo Nørregaard

    2011-01-01

    of dimensions of extension that can be exploited without performing modification of existing types. Thus, dynamic links make it possible to enforce the open/closed principle in situations where it would otherwise not be possible. We present Decouplink – a library-based implementation of dynamic links for Java...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... people use to weigh risks and benefits when making decisions. This page connects you to information about the link between drug abuse and HIV infection. It contains information for young people, parents and teachers, and the media with links to our latest research findings and ...

  20. SetLink: the CERN Document Server Link Manager

    OpenAIRE

    Le Meur, Jean-Yves; McGlashan, David

    2000-01-01

    This paper analyses the problems encountered by electronic libraries to cope with long term keeping of on-line documents. What is the best solution not to fill in a library system with non persistent addresses? Different possible solutions are studied, based on the experience of the CERN Document Server and its library. This paper will stress the importance of using a Link Manager for any long term Web server. It will explain how the CERN SetLink Link Manager is designed to handle a wide ...

  1. The Missing Link: The Use of Link Words and Phrases as a Link to Manuscript Quality

    Science.gov (United States)

    Onwuegbuzie, Anthony J.

    2016-01-01

    In this article, I provide a typology of transition words/phrases. This typology comprises 12 dimensions of link words/phrases that capture 277 link words/phrases. Using QDA Miner, WordStat, and SPSS--a computer-assisted mixed methods data analysis software, content analysis software, and statistical software, respectively--I analyzed 74…

  2. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... patients who do not abuse drugs. In animal studies, methamphetamine has been shown to increase the amount ... behaviors. NIDA researchers have studied and continue to study the links between drug abuse and HIV/AIDS. ...

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... never thought that one party could change their lives , but now their night out always will be ... reach parents and teachers—influential figures in the lives of young people—with the Learn the Link ...

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Campaign Overview The Learn the Link campaign uses TV, print, and Web public service announcements (PSAs), as ... CW BET NBC ABC FOX LATV My Network TV Organizations: AIDS.gov AIDS Alliance for Children, Youth ...

  5. EPA Linked Open Data (Collection)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This is a collection item referencing the following EPA Linked Data resources: - EPA Facility Registry Service (FRS) - EPA Substance Registry Service (SRS) -...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... AIDS (acquired immune deficiency syndrome). AIDS is a disease of the immune system for which there is ... the present time. The virus (HIV) and the disease it causes (AIDS) are often linked and referred ...

  7. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... public discussions on using new media effectively in response to HIV/AIDS, as well as HIV/AIDS ... HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, we ...

  8. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and teachers, and the media with links to our latest research findings and news updates. Read on ... the "Text Message" spot) from her own perspective. Our other campaign materials include print PSAs, Web banner ...

  9. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Prevention Recovery Substance Use and SUDs in LGBT Populations Treatment Trends & Statistics Women and Drugs Publications Search ... the link between drug abuse and HIV/AIDS, populations most at risk, trends in HIV/AIDS, and ...

  10. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter ... Network TV Organizations: AIDS.gov AIDS Alliance for Children, Youth and Families The American Academy of Child & ...

  11. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... of HIV infection in the United States. Drugs can change the way the brain works, disrupting the ... linked and referred to as "HIV/AIDS." HIV can be transferred between people if an infected person's ...

  12. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... HIV Learn the Link - Drugs and HIV ... the parts of the brain that people use to weigh risks and benefits when making decisions. This page connects you to information about the ...

  13. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... their lives , but now their night out always will be associated with HIV/AIDS. The “d’cisions” ... for breaking the harmful links between them, we will continue to update this Web site. Sincerely, Nora ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... En español Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook ... HIV infection. It contains information for young people, parents and teachers, and the media with links to ...

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Addiction Science Adolescent Brain Comorbidity College-Age & Young Adults Criminal Justice Drugged Driving Drug Testing Drugs and ... Link campaign. This campaign shows teens and young adults that non-injection drug use and alcohol use ...

  16. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... affect anyone. Watch the “d’cisions” Videos Campaign Materials After the Party Posters: We have developed posters ... the Learn the Link message. Campaign messages and materials were tested among various groups of young people, ...

  17. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... to this site at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and to ...

  18. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... other organizations in your tweets to spread the word even further. Tweet About Learn the Link To ... other organizations in your tweets to spread the word even further. Share with Flickr, Pinterest or Instagram ...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... En español Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse Commonly Abused Drugs Charts Emerging Trends and Alerts ...

  1. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... that use text messaging as a means of communication. The "Text Message" PSA features two young girls ... Drugs + HIV > Learn the Link campaign. This campaign shows teens and young adults that non-injection drug ...

  2. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available Skip to main content En español Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS ...

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... easily copy and paste to help show your support for Learn the Link . Be sure to check ... the discussion between friends, and the importance of family. For more information, read a message from the ...

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... can affect anyone. Watch the “d’cisions” Videos Campaign Materials After the Party Posters: We have developed ... share on your social media accounts. About the Campaign Overview The Learn the Link campaign uses TV, ...

  5. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... in recent years, HIV is no longer a death sentence, as it was when the epidemic began. ... Science USA Science & Engineering Festival Drug & Alcohol Chat Day HBO Addiction Project Learn the Link Videos NIDA ...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... NIDA Flickr account for images. Share your favorite image! Check out all of our ... Link campaign uses TV, print, and Web public service announcements (PSAs), as well as posters, ...

  7. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available Skip to main content En español Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu ...

  8. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... among the main factors in the spread of HIV infection in the United States. Drugs can change the ... information about the link between drug misuse and HIV infection. It contains information for young people, parents and ...

  9. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... for Addiction Science USA Science & Engineering Festival Drug & Alcohol Chat Day HBO Addiction Project Learn the Link Videos NIDA and Scholastic - Heads Up NIDA Media Campaign Postcards Public Service Announcements Other Government Observances ...

  10. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... announcements (PSAs) that use text messaging as a means of communication. The "Text Message" PSA features two ... teens and young adults have never known a world without it. NIDA’s "Learn the Link" campaign continues ...

  11. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the main factors in the spread of HIV infection in the United States. Drugs can change the ... about the link between drug abuse and HIV infection. It contains information for young people, parents and ...

  12. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... has shown that treating drug abuse is an effective way to prevent the spread of HIV. Drug ... HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, we ...

  13. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... she went to a party and under the influence of drugs and alcohol engaged in risky sexual ... other organizations in your tweets to spread the word even further. Tweet About Learn the Link To ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... between drug abuse and HIV/AIDS. In the early years of the HIV epidemic, it became clear ... HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, we ...

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... HIV/AIDS, and the general public. U.S. National Library of Medicine HIV/AIDS ... send the message to young people and to parents, teachers, and the media about the link between ...

  16. Medicare and Medicaid Linked Files

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Medicare-Medicaid Linked Enrollee Analytic Data Source (MMLEADS) has been developed to allow for the examination of all Medicare and Medicaid enrollment and...

  17. Protein Linked to Atopic Dermatitis

    Science.gov (United States)

    ... Research Matters January 14, 2013 Protein Linked to Atopic Dermatitis Normal skin from a mouse (left) shows no ... that lack of a certain protein may trigger atopic dermatitis, the most common type of eczema. The finding ...

  18. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Web banner ads that you can download and add to your Web site. Please link these banners ... abuse and HIV. Post on Facebook or Twitter ; add photos to your Flickr , Pinterest , and Instagram pages; ...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... events, and radio stations for helping to raise awareness of the link between non-injection drug use and HIV. Television Networks: MunDos Azteca America Univision Telemundo Galavision ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... through 15 (as well as their parents and teachers). It provides them with useful information on the ... the message to young people and to parents, teachers, and the media about the link between drug ...

  1. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... HIV (human immunodeficiency virus) is the virus that causes AIDS (acquired immune deficiency syndrome). AIDS is a ... time. The virus (HIV) and the disease it causes (AIDS) are often linked and referred to as " ...

  2. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Prevention Recovery Substance Use and SUDs in LGBT Populations Treatment Trends & Statistics Women and Drugs Publications Search ... the link between drug misuse and HIV/AIDS, populations most at risk, trends in HIV/AIDS, and ...

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... NIDA’s "Learn the Link" campaign continues to raise awareness among this generation of the real risks of ... Collaborators Thanks to Those Who Have Helped Raise Awareness of Our Campaign! NIDA acknowledges the following television ...

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... causes AIDS (acquired immune deficiency syndrome). AIDS is a disease of the immune system for which there ... causes (AIDS) are often linked and referred to as "HIV/AIDS." HIV can be transferred between people ...

  5. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... injury to cells in the brain and cognitive impairment among people who use methamphetamine than among HIV ... Link campaign. This campaign shows teens and young adults that non-injection drug use and alcohol use ...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... It contains information for young people, parents and teachers, and the media with links to our latest ... through 15 (as well as their parents and teachers). It provides them with useful information on the ...

  7. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, we ... Children, Youth and Families The American Academy of Child & Adolescent Psychiatry (AACAP) The United Negro College Fund, ...

  8. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Learn the Link Videos NIDA and Scholastic - Heads Up NIDA Media Campaign Postcards Public Service Announcements Other Government Observances for Substance Abuse Education Contact the Press Office Meetings & Events Media Guide ...

  9. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... NIDA Science Fair Award for Addiction Science USA Science & Engineering Festival Drug & Alcohol Chat Day HBO Addiction Project Learn the Link Videos NIDA and Scholastic - Heads ...

  10. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... never thought that one party could change their lives, but now their night out always will be ... reach parents and teachers-influential figures in the lives of young people-with the Learn the Link ...

  11. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... affect anyone. Watch the “d’cisions” Videos Campaign Materials After the Party Posters: We have developed posters ... behaviors. NIDA researchers have studied and continue to study the links between drug misuse and HIV/AIDS. ...

  12. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Drugs and HIV Learn the Link - Drugs and HIV Email Facebook Twitter 2005 –Ongoing Behaviors associated with ... Send the Message . Get the Facts What are HIV and AIDS? HIV (human immunodeficiency virus) is the ...

  13. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... teens and young adults have never known a world without it. NIDA’s "Learn the Link" campaign continues ... drug abuse and HIV/AIDS. In the early years of the HIV epidemic, it became clear that ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... to-Read Drug Facts Web site describes the dangers of drug abuse and its link to HIV ... available for your use to share on your social media accounts. ... educational institutions, magazines, newspapers, companies, events, and ...

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and the discovery of promising treatment interventions for breaking the harmful links between them, we will continue to update this ... Media Campaign Postcards Public Service Announcements Other ...

  16. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... patients who do not misuse drugs. In animal studies, methamphetamine has been shown to increase the amount ... behaviors. NIDA researchers have studied and continue to study the links between drug misuse and HIV/AIDS. ...

  17. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and HIV. We have produced a set of multicultural public service announcements (PSAs) that use text messaging ... NIDA’s "Learn the Link" campaign continues to raise awareness among this generation of the real risks of ...

  18. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... easily copy and paste to help show your support for Learn the Link . Be sure to check ... View Videos "After the Party" "Text Message" NIDA Home Site Map Accessibility Privacy FOIA(NIH) Working at ...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... pictures from NIDA images. Visit the NIDA Flickr account for images. Share your favorite image! Check out ... your use to share on your social media accounts. About the Campaign Overview The Learn the Link ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... NIDA Science Fair Award for Addiction Science USA Science & Engineering Festival Drug & Alcohol Chat Day HBO Addiction Project Learn the Link Videos NIDA and Scholastic - Heads Up NIDA Media Campaign Postcards Public Service Announcements Other Government Observances ...

  1. Linked data and user interaction

    CERN Document Server

    Cervone, H Frank

    2015-01-01

    This collection of research papers provides extensive information on deploying services, concepts, and approaches for using open linked data from libraries and other cultural heritage institutions. With a special emphasis on how libraries and other cultural heritage institutions can create effective end user interfaces using open, linked data or other datasets. These papers are essential reading for any one interesting in user interface design or the semantic web.

  2. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Yong, X.

    2000-01-01

    Duration Calculus (DC) is an interval-based real-time logic, which can be used in capturing and eliciting users' real-time requirements. The Timed RAISE Specification Language (TRSL) is an extension of the RAISE Specification Language with real-time features. This paper links DC and TRSL together...... approach for linking state-based real-time logics together with event-based, timed process algebra languages....

  3. Linking Ethics and Economic Growth

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul

    2012-01-01

    Hunt (2012) builds on his work concerning ethics and resource-advantage theory to link personal ethical standards, societal norms, and economic growth but offers few details concerning the precise mechanisms that link ethics and growth. This comment suggests a number of such mechanisms...... – for example, the influence of prevailing ethical norms on the aggregate elasticity of substitution and, therefore, total factor productivity and growth....

  4. Signed Link Analysis in Social Media Networks

    OpenAIRE

    Beigi, Ghazaleh; Tang, Jiliang; Liu, Huan

    2016-01-01

    Numerous real-world relations can be represented by signed networks with positive links (e.g., trust) and negative links (e.g., distrust). Link analysis plays a crucial role in understanding the link formation and can advance various tasks in social network analysis such as link prediction. The majority of existing works on link analysis have focused on unsigned social networks. The existence of negative links determines that properties and principles of signed networks are substantially dist...

  5. LinkMind: Link Optimization in Swarming Mobile Sensor Networks

    Directory of Open Access Journals (Sweden)

    Trung Dung Ngo

    2011-08-01

    Full Text Available A swarming mobile sensor network is comprised of a swarm of wirelessly connected mobile robots equipped with various sensors. Such a network can be applied in an uncertain environment for services such as cooperative navigation and exploration, object identification and information gathering. One of the most advantageous properties of the swarming wireless sensor network is that mobile nodes can work cooperatively to organize an ad-hoc network and optimize the network link capacity to maximize the transmission of gathered data from a source to a target. This paper describes a new method of link optimization of swarming mobile sensor networks. The new method is based on combination of the artificial potential force guaranteeing connectivities of the mobile sensor nodes and the max-flow min-cut theorem of graph theory ensuring optimization of the network link capacity. The developed algorithm is demonstrated and evaluated in simulation.

  6. LinkMind: Link Optimization in Swarming Mobile Sensor Networks

    DEFF Research Database (Denmark)

    Ngo, Trung Dung

    2012-01-01

    optimization of swarming mobile sensor networks. The new method is based on combination of the artificial potential force guaranteeing connectivities of the mobile sensor nodes and the max-flow min-cut theorem of graph theory ensuring optimization of the network link capacity. The developed algorithm......A swarming mobile sensor network is comprised of a swarm of wirelessly connected mobile robots equipped with various sensors. Such a network can be applied in an uncertain environment for services such as cooperative navigation and exploration, object identification and information gathering. One...... of the most advantageous properties of the swarming wireless sensor network is that mobile nodes can work cooperatively to organize an ad-hoc network and optimize the network link capacity to maximize the transmission of gathered data from a source to a target. This paper describes a new method of link...

  7. High Performance Flexible Thermal Link

    Science.gov (United States)

    Sauer, Arne; Preller, Fabian

    2014-06-01

    The paper deals with the design and performance verification of a high performance and flexible carbon fibre thermal link.Project goal was to design a space qualified thermal link combining low mass, flexibility and high thermal conductivity with new approaches regarding selected materials and processes. The idea was to combine the advantages of existing metallic links regarding flexibility and the thermal performance of high conductive carbon pitch fibres. Special focus is laid on the thermal performance improvement of matrix systems by means of nano-scaled carbon materials in order to improve the thermal performance also perpendicular to the direction of the unidirectional fibres.One of the main challenges was to establish a manufacturing process which allows handling the stiff and brittle fibres, applying the matrix and performing the implementation into an interface component using unconventional process steps like thermal bonding of fibres after metallisation.This research was funded by the German Federal Ministry for Economic Affairs and Energy (BMWi).

  8. Fix Broken and Redirected Links Using Group Dashboard Link Report

    Science.gov (United States)

    Learn how to use the tools provided by Drupal in the Group Dashboard to find and correct links on your site that are broken (404 and 403 error codes), or that redirect (301 and 302), for example to a homepage rather than the originally intended content.

  9. When He Said Linking, He Really Meant Linking

    Science.gov (United States)

    Chudnov, Daniel

    2009-01-01

    There are many reasons to improve web links, starting with their design. The author tends to think about "design" on the web in terms of two things: (1) graphic/industrial design; and (2) human usability. A nice, clean URI (uniform resource identifier) that does not change, is readable to humans, is amenable to common web behaviors such as…

  10. The Audacity of Fiber-Wireless (FiWi) Networks

    Science.gov (United States)

    Maier, Martin; Ghazisaidi, Navid; Reisslein, Martin

    A plethora of enabling optical and wireless technologies have been emerging that can be used to build future-proof bimodal fiber-wireless (FiWi) broadband access networks. After overviewing key enabling radio-over-fiber (RoF) and radio-and-fiber (R&F) technologies and briefly surveying the state of the art of FiWi networks, we introduce an Ethernet-based access-metro FiWi network, called SuperMAN, that integrates next-generation WiFi and WiMAX networks with WDM-enhanced EPON and RPR networks. Throughout the paper we pay close attention to the technical challenges and opportunities of FiWi networks, but also elaborate on their societal benefits and potential to shift the current research focus from optical-wireless networking to the exploitation of personal and in-home computing facilities to create new unforeseen services and applications as we are about to enter the Petabyte age.

  11. Genetics Home Reference: X-linked adrenoleukodystrophy

    Science.gov (United States)

    ... Home Health Conditions X-linked adrenoleukodystrophy X-linked adrenoleukodystrophy Printable PDF Open All Close All Enable Javascript ... view the expand/collapse boxes. Description X-linked adrenoleukodystrophy is a genetic disorder that occurs primarily in ...

  12. Genetics Home Reference: X-linked thrombocytopenia

    Science.gov (United States)

    ... Home Health Conditions X-linked thrombocytopenia X-linked thrombocytopenia Printable PDF Open All Close All Enable Javascript ... view the expand/collapse boxes. Description X-linked thrombocytopenia is a bleeding disorder that primarily affects males. ...

  13. micromap: A Package for Linked Micromaps

    Science.gov (United States)

    The R package micromap is used to create linked micromaps, which display statistical summaries associated with areal units, or polygons. Linked micromaps provide a means to simultaneously summarize and display both statistical and geographic distributions by linking statistical ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... Daytona Beach Film Festival Big Mini Film Festival Visual AIDS Bus Boys and Poets Sistahs Getting Real ...

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the News NIDA Notes Podcasts E-Newsletters Public Education Projects Contact the Press Office Meetings & Events Media ... found at USA.gov . Home » News & Events » Public Education Projects » Learn the Link - Drugs and HIV Learn ...

  16. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and to ... available for your use to share on your social media accounts. About the Campaign Overview The Learn the ...

  17. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... Commission on AIDS Metro Teen Aids Azteca America Foundation/Vive Sin Drogras AdCouncil DC Department of Health ...

  18. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, we will continue to update this Web site. Sincerely, Nora D. Volkow, M.D. Director National Institute on Drug Abuse Collaborators Thanks to Those Who Have Helped Raise ...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... States. Drugs can change the way the brain works, disrupting the parts of the brain that people use to weigh risks and benefits when making decisions. This page connects you to information about the link between drug abuse and HIV infection. It contains information for young ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... M.C. et al. “Methamphetamine increases brain viral load and activates natural killer cells in simian immunodeficiency ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  1. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    ... tested using the coherence of time series to determine the causality and related orientation. The resulting link orientations at the plate boundary conditions indicate that causal triggering seems to be localized along a major fault, as a stress transfer between two major faults, and parallel to the geothermal area extension.

  2. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... link between non-injection drug use and HIV. Television Networks: MunDos Azteca America Univision Telemundo Galavision Telefutura CW BET NBC ABC FOX LATV My Network TV Organizations: AIDS.gov AIDS Alliance for Children, Youth and Families The American Academy of Child & ...

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse Commonly Abused Drugs Charts ... x 5 (PDF, 212KB) Small (PDF, 451 KB) Color 7 x 10 (PDF, 717KB) 7 x 5 ( ...

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse Commonly Abused Drugs Charts ... Daytona Beach Film Festival Big Mini Film Festival Visual AIDS Bus Boys and Poets Sistahs Getting Real ...

  5. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... in recent years, HIV is no longer a death sentence, as it was when the epidemic began. ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Tobacco/Nicotine and E-Cigs Other Drugs Related Topics Addiction Science Adolescent Brain Comorbidity College-Age & Young ... parties or hanging out with friends? It’s a topic you can’t ignore. Learn the Link: http:// ...

  7. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and HIV. We have produced a set of multicultural public service announcements (PSAs) that use text messaging ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  8. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... News NIDA Notes Podcasts E-Newsletters Public Education Projects Contact the Press Office Meetings & Events Media Guide About NIDA Director's Page ... Engineering Festival Drug & Alcohol Chat Day HBO Addiction Project Learn the Link ... Guide Get this Publication Español ...

  9. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... GA: CDC, DHHS. Retrieved June 2012 How are Drug Abuse and HIV Related? Drug abuse and addiction have been linked with HIV/AIDS ... in this regard, the role that non-injection drug abuse plays in the spread of HIV is less ...

  10. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the News NIDA Notes Podcasts E-Newsletters Public Education Projects Contact the Press Office Meetings & Events Media ... Plan Search Share Print Home » News & Events » Public Education Projects » Learn the Link - Drugs and HIV Learn ...

  11. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... gov/1kSfBiz ​ Mention your friends, colleagues, or other organizations in your tweets to spread the word even ...

  12. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... groups of young people, guiding the use of technology, the discussion between friends, and the importance of ...

  13. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... blood cell that is crucial to the normal function of the human immune system. Loss of these ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... no cure, at the present time. The virus (HIV) and the disease it causes (AIDS) are often linked and referred ... an important role in providing current information on HIV/AIDS and related diseases, counseling and testing services, and referrals for medical ...

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Color (PDF, 2.3 MB) Black and White (PDF, 1.1 MB) Web Banner We have created animated Web banner ads that you can download and add to your Web site. Please link these banners back to this site at: http://www. ...

  16. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... following television networks, organizations, educational institutions, magazines, newspapers, companies, events, and radio stations for helping to raise ...

  17. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... young people and to parents, teachers, and the media about the link between drug misuse and HIV. We have produced a set of multicultural public service announcements (PSAs) that use text messaging as a means of communication. The "Text Message" PSA features two young girls ...

  18. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse Commonly Abused Drugs Charts Emerging Trends and Alerts Alcohol Club ...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... with HIV is a key predictor of the development of AIDS. Because of their compromised immune system, ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Drug use disorder treatment programs also serve an important role in providing current information on HIV/AIDS ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  1. X-linked Alport syndrome

    DEFF Research Database (Denmark)

    Jais, Jean Philippe; Knebelmann, Bertrand; Giatras, Iannis

    2003-01-01

    Alport syndrome (AS) is a type IV collagen hereditary disease characterized by progressive hematuric nephritis, hearing loss, and ocular changes. Mutations in the COL4A5 collagen gene are responsible for the more common X-linked dominant form of the disease characterized by much less severe disea...

  2. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and Drugs Publications Search Publications Orderable DrugFacts Research Reports Mind Over Matter Science of Addiction Funding Funding ... transmitting HIV/AIDS or other infectious diseases. Research Reports: HIV/AIDS : Explores the link between drug misuse ...

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... HIV to their babies during pregnancy, delivery, and breastfeeding. HIV destroys a certain kind of white blood ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the amount of HIV in brain cells 1 . Drug abuse treatment. Since the late 1980s, research has shown that ... we learn more about the critical connection between drug abuse and HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, ...

  5. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Badges Other Resources Strategic Plan Search Share Print Home » News & Events » Public Education Projects » Learn the Link - Drugs and HIV Learn ... Service Announcements Other Government Observances for Substance Abuse Education Contact the Press Office Meetings & Events Media Guide ... NIDA Home Site Map Accessibility Privacy FOIA(NIH) Working at ...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... she went to a party and under the influence of drugs and alcohol engaged in risky sexual ... learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and to ...

  7. What is Linked Historical Data?

    NARCIS (Netherlands)

    Meroño-Peñuela, A.; Hoekstra, R.; Janowicz, K.; Schlobach, S.; Lambrix, P.; Hyvönen, E.

    2014-01-01

    Datasets that represent historical sources are relative newcomers in the Linked Open Data (LOD) cloud. Following the standard LOD practices for publishing historical sources raises several questions: how can we distinguish between RDF graphs of primary and secondary sources? Should we treat archived

  8. What Is Linked Historical Data?

    NARCIS (Netherlands)

    Meroño-Peñuela, Albert; Hoekstra, Rinke; Janowicz, Krzysztof; Schlobach, Stefan; Lambrix, Patrick; Hyvönen, Eero

    2014-01-01

    Datasets that represent historical sources are relative new- comers in the Linked Open Data (LOD) cloud. Following the standard LOD practices for publishing historical sources raises several questions: how can we distinguish between RDF graphs of primary and secondary sources? Should we treat

  9. New links in the family

    NARCIS (Netherlands)

    Marion Duimel; Jos de Haan

    2007-01-01

    Original title: Nieuwe links in het gezin. Virtually all families with teenagers have at least one computer with an Internet connection, often more. Teenagers spend much of their daily lives on the Internet. They use it to communicate with each other, to do their schoolwork, to meet new

  10. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... HIV > Learn the Link campaign. This campaign shows teens and young adults that non-injection drug use and alcohol use can lead to poor ... been with us for three decades now. Today's teens and young adults have never ... of the real risks of drug use for transmitting HIV, and it encourages them ...

  11. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... is a disease of the immune system for which there is treatment, but no cure, at the present time. The virus (HIV) and the disease it causes (AIDS) are often linked and referred to as "HIV/AIDS." ...

  12. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... NIDA Flickr account for images. Share your favorite image! Check out all of our downloads. Show Learn the Link with Videos We have numerous videos on our website that are available for your use to share on your social media accounts. About the Campaign Overview The Learn the ...

  13. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the Director of the National Institute on Drug Abuse, Dr. Nora D. Volkow. Message from the Director The Link Between HIV/AIDS and Drug Misuse The HIV/AIDS epidemic has been with us for three decades now. Today's teens and young adults have never known a world without it. ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Bath Salts) Tobacco/Nicotine and E-Cigs Other Drugs Related Topics Addiction Science Adolescent Brain Comorbidity College-Age & Young Adults ... 2012 How are Drug Abuse and HIV Related? Drug abuse and addiction have been linked with HIV/AIDS since the ...

  15. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... about the critical connection between drug abuse and HIV/AIDS and the discovery of promising treatment interventions for breaking the harmful links between them, we will continue to update this Web site. Sincerely, Nora D. Volkow, M. ...

  16. Link Dependent Adaptive Radio Simulation

    Science.gov (United States)

    2014-06-01

    of Electrical and Computer Engineering Morgan State University ABSTRACT This paper shows the optimized Link Dependent Adaptive Radio (LDAR...Instrumentation (PEO STRI ). 9 9. REFERENCES [1] M. Elrais, B. Mengiste, B. Gautam and E. Dambia, "Variable OFDM Performance on Aeronautical

  17. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available Skip to main content En español Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse ...

  18. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Adolescent Brain Comorbidity College-Age & Young Adults Criminal Justice Drugged Driving Drug Testing Drugs and the Brain ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ...

  19. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... News NIDA Notes Podcasts E-Newsletters Public Education Projects Contact the Press Office Meetings & Events Media Guide ... Search Share Print Home » News & Events » Public Education Projects » Learn the Link - Drugs and HIV Learn the ...

  20. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available Skip to main content En español Researchers Medical & Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr RSS Menu Home Drugs of Abuse Commonly Abused Drugs Charts Emerging Trends and Alerts Alcohol ...

  1. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Health Professionals Patients & Families Parents & Educators Children & Teens Search Connect with NIDA : Facebook LinkedIn Twitter YouTube Flickr ... Populations Treatment Trends & Statistics Women and Drugs Publications Search Publications Orderable DrugFacts Research Reports Mind Over Matter ...

  2. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... depict the devastating consequences of compromised judgment and critical thinking that can result from drug use. Young women ... HIV epidemic. As we learn more about the critical connection between drug ... treatment interventions for breaking the harmful links between them, we ...

  3. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... and what to do to counter these trends. Online Resources NIDA for Teens Web site : This Web ... at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 460x80 486x60 ...

  4. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... available for your use to share on your social media accounts. About the Campaign Overview The Learn ...

  5. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... www.cdc.gov/actagainstaids/basics/whatishiv.html ). Atlanta, GA: CDC, DHHS. Retrieved November 2017. How are Drug Misuse and HIV Related? Drug misuse and addiction have been linked with HIV/AIDS since the beginning of the epidemic. Although injection drug use is well known in this ...

  6. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... the Link campaign. This campaign shows teens and young adults that non-injection drug use and alcohol use can lead to poor decision making, which can result in risky sexual behaviors and HIV infection. Although the characters are fictional, ...

  7. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... projects/learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and ... NIDA TV PEERx Drugs & Health Blog The NIDA Science Fair Award for Addiction Science USA Science & Engineering ...

  8. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... CDC, DHHS. Retrieved June 2012 How are Drug Abuse and HIV Related? Drug abuse and addiction have been linked with HIV/AIDS ... this regard, the role that non-injection drug abuse plays in the spread of HIV is less ...

  9. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... message to America's youth that using drugs and alcohol even once can have serious health consequences. We also work to reach parents and ... Drug & Alcohol Facts Week NIDA TV PEERx Drugs & Health Blog The NIDA ... Festival Drug & Alcohol Chat Day HBO Addiction Project Learn the Link ...

  10. Knots, Links and 4-Manifolds

    CERN Document Server

    Fintushel, R; Fintushel, Ronald; Stern, Ronald J.

    1996-01-01

    In this paper we investigate the relationship between isotopy classes of knots and links in S^3 and the diffeomorphism types of homeomorphic smooth 4-manifolds. As a corollary of this initial investigation, we begin to uncover the surprisingly rich structure of diffeomorphism types of manifolds homeomorphic to the K3 surface.

  11. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... who engage in drug use or high-risk behaviors associated with drug use also put themselves at risk for contracting or transmitting HIV/AIDS or other infectious diseases. Research Reports: HIV/AIDS : Explores the link between drug ...

  12. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... HIV/AIDS, and the general public. U.S. National Library of Medicine HIV/AIDS Information : Specialized Information Services. ... this site at: http://www.drugabuse.gov/news-events/public-education-projects/learn-link-drugs-hiv . 120x90 ...

  13. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... learn-link-drugs-hiv . 120x90 460x80 486x60 Social Media Send the message to young people and to ... groups of young people, guiding the use of technology, the discussion between friends, and the importance of ...

  14. Drugs + HIV, Learn the Link

    Medline Plus

    Full Text Available ... Send the Message . Get the Facts What are HIV and AIDS? HIV (human immunodeficiency virus) is the virus that ... AIDS) are often linked and referred to as "HIV/AIDS." HIV can be transferred between people if an ...

  15. LinkED: A Novel Methodology for Publishing Linked Enterprise Data

    Directory of Open Access Journals (Sweden)

    Shreyas Suresh Rao

    2017-01-01

    Full Text Available Semantic Web technologies have redefined and strengthened the Enterprise-Web interoperability over the last decade. Linked Open Data (LOD refers to a set of best practices that empower enterprises to publish and interlink their data using existing ontologies on the World Wide Web. Current research in LOD focuses on expert search, the creation of unified information space and augmentation of core data from an enterprise context. However, existing approaches for publication of enterprise data as LOD are domain-specific, ad-hoc and suffer from lack of uniform representation across domains. The paper proposes a novel methodology called LinkED that contributes towards LOD literature in two ways: (a streamlines the publishing process through five stages of cleaning, triplification, interlinking, storage and visualization; (b addresses the latest challenges in LOD publication, namely: inadequate links, inconsistencies in the quality of the dataset and replicability of the LOD publication process. Further, the methodology is demonstrated via the publication of digital repository data as LOD in a university setting, which is evaluated based on two semantic standards: Five-Star model and data quality metrics. Overall, the paper provides a generic LOD publication process that is applicable across various domains such as healthcare, e-governance, banking, and tourism, to name a few.

  16. The importance of link evidence in Wikipedia

    NARCIS (Netherlands)

    Kamps, J.; Koolen, M.

    2008-01-01

    Wikipedia is one of the most popular information sources on the Web. The free encyclopedia is densely linked. The link structure in Wikipedia differs from the Web at large: internal links in Wikipedia are typically based on words naturally occurring in a page, and link to another semantically

  17. Why copyright and linking can tango

    NARCIS (Netherlands)

    Tsoutsanis, A.

    2014-01-01

    This article discusses the legal status of links, in connection with the pending cases before the Court of Justice in Svensson, C More and BestWater. Hyperlinks, deep links, framed links and embedded links are discussed. It focuses on the Opinion of the ‘European Copyright Society’ on the Svensson

  18. Propensity to Click on Suspicious Links

    DEFF Research Database (Denmark)

    Sudzina, Frantisek; Pavlicek, Antonin

    2017-01-01

    There already exists a certain, not huge, body of knowledge about impact of personality traits on susceptibility to phishing. But there is a gap when it comes specifically to phishing with links pretending to lead to deal sites. The paper analyzes if gender, age and personality traits influence.......1. Openness to experience was linked positively linked to responsible behavior, narcissism was negatively linked....

  19. Using turbocodes on optical links

    Directory of Open Access Journals (Sweden)

    Glenn Claes

    2006-04-01

    Full Text Available The fast evolving telecommunication world is permanently in search for faster and better communication links. On one hand, turbo codes are like a dream come true. Due to their amazing performance, they have become the reference in the word of error detecting and correcting codes. On the other hand, broadband transmission channels like optical fibres can meet the need for higher transmission velocity. In this paper therefore we will bring these two elements together and thus the performance of turbocodes on optical links will be studied. First the turbocode will be optimised throughout an individual analysis of each of its design parameters. Moreover it wil be shown that turbocodes have much better performance than the well known Reed-Solomon codes. Finally we will show that the 8Bit/10Bit code, which is required to comply with the Gigabit Ethernet standard, becomes superfluous when working with turbocodes. All tests were carried out on multimode graded-index glass fibres.

  20. Collagen cross linking: Current perspectives

    Directory of Open Access Journals (Sweden)

    Srinivas K Rao

    2013-01-01

    Full Text Available Keratoconus is a common ectatic disorder occurring in more than 1 in 1,000 individuals. The condition typically starts in adolescence and early adulthood. It is a disease with an uncertain cause and its progression is unpredictable, but in extreme cases, vision deteriorates and can require corneal transplant surgery. Corneal collagen cross-linking (CCL with riboflavin (C3R is a recent treatment option that can enhance the rigidity of the cornea and prevent disease progression. Since its inception, the procedure has evolved with newer instrumentation, surgical techniques, and is also now performed for expanded indications other than keratoconus. With increasing experience, newer guidelines regarding optimization of patient selection, the spectrum of complications and their management, and combination procedures are being described. This article in conjunction with the others in this issue, will try and explore the uses of collagen cross-linking (CXL in its current form.

  1. EUROSENTIMENT: Linked Data Sentiment Analysis

    OpenAIRE

    Sánchez Rada, Juan Fernando; Vulcu, Gabriela; Iglesias Fernandez, Carlos Angel; Buitelaar, Paul

    2014-01-01

    Sentiment and Emotion Analysis strongly depend on quality language resources, especially sentiment dictionaries. These resources are usually scattered, heterogeneous and limited to specific domains of appli- cation by simple algorithms. The EUROSENTIMENT project addresses these issues by 1) developing a common language resource representation model for sentiment analysis, and APIs for sentiment analysis services based on established Linked Data formats (lemon, Marl, NIF and ONYX) 2) by creati...

  2. Managing Your Team's Weakest Link.

    Science.gov (United States)

    Hills, Laura

    2015-01-01

    Do you have a poor-performing employee on your medical practice team? If so, you're not alone. Unfortunately, this is a problem that many medical practice managers face. This article describes the best strategies for managing your team's weakest link. It explores common yet very difficult circumstances that cause low employee performance and that test the patience, heart, and skills of a practice manager. It guides readers through a process of self-discovery to determine whether their negative biases or grudges may be causing employees to perform poorly. It suggests several possible other reasons for weak employee performance, including problems with the job, practice, leadership, communication, and fit between the employee and the job. This article also suggests the best strategy for communicating concerns about performance to the weakest-link employee. It offers guidance to practice managers about protecting their time and energy when handling a poor performer. It provides a simple formula for calculating the cost of a low-performing employee, 10 possible personal reasons for the employee's poor work performance, specific questions to ask to uncover the reasons for poor performance, and an eight-rule strategy for confronting poor performance effectively. Finally, this article offers practice managers a practical strategy for handling resistance from their weakest link, illustrated with a sample dialogue.

  3. Linking GHG Emission Trading Systems and Markets

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    Several different types of links are possible between different GHG-mitigation systems. These include: Linking two or more emission trading schemes so that emissions trading can occur both within and between different schemes ('direct links'); and Linking emission trading systems to registries/mechanisms and systems that generate offsets from project based mechanisms or from direct purchases/transfers of AAUs ('indirect links').

  4. Linking Maxwell, Helmholtz and Gauss through the Linking Integral

    OpenAIRE

    De Zela, F.

    2004-01-01

    We take the Gauss' linking integral of two curves as a starting point to discuss the connection between the equation of continuity and the inhomogeneous Maxwell equations. Gauss' formula has been discussed before, as being derivable from the line integral of a magnetic field generated by a steady current flowing through a loop. We argue that a purely geometrical result - such as Gauss' formula - cannot be claimed to be derivable from a law of Nature, i.e., from one of Maxwell's equations, whi...

  5. Broken links and black boxes

    DEFF Research Database (Denmark)

    Sindbæk, Søren Michael

    2013-01-01

    Long-distance communication has emerged as a particular focus for archaeological exploration using network theory, analysis, and modelling. Initial attempts to adapt methods from social network analysis to archaeological data have, however, struggled to produce decisive results. This paper argues...... that the archaeological study of communication networks in the past calls for radically different analytical methods from those employed by most other forms of social network analysis. The fragmentary archaeological evidence presents researchers with the task of reconstructing the broken links of a ruined network from...

  6. Linking Customer Interaction and Innovation

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Laursen, Keld; Pedersen, Torben

    2011-01-01

    , firms that attempt to leverage user and customer knowledge in the context of innovation must design an internal organization appropriate to support it. This can be achieved in particular through the use of new organizational practices, notably, intensive vertical and lateral communication, rewarding...... employees for sharing and acquiring knowledge, and high levels of delegation of decision rights. In this paper, six hypotheses were developed and tested on a data set of 169 Danish firms drawn from a 2001 survey of the 1,000 largest firms in Denmark. A key result is that the link from customer knowledge...

  7. X-linked Alport syndrome

    DEFF Research Database (Denmark)

    Jais, J P; Knebelmann, B; Giatras, I

    2000-01-01

    . Considerable allelic heterogeneity has been observed. A "European Community Alport Syndrome Concerted Action" has been established to delineate accurately the AS phenotype and to determine genotype-phenotype correlations in a large number of families. Data concerning 329 families, 250 of them with an X......-linked transmission, were collected. Characteristics of the 401 male patients belonging to the 195 families with COL4A5 mutation are presented. All male patients were hematuric, and the rate of progression to end-stage renal failure and deafness was mutation-dependent. Large deletions, non-sense mutations, or small...

  8. Inter-satellite laser link simulation analysis

    Science.gov (United States)

    Tong, Lanjuan; Guan, Hui; Wang, Zhilin

    2015-11-01

    The characteristic of satellite communication link was firstly described and four application modes were put forward. By comparison, it is suggested that microwave link is used in satellite-to-ground communication and laser link is used in inter-satellite communication. Secondly the condition and composition of laser link establishment was analyzed and laser link model was set up, and the principle and composition of APT system was described. Finally, based on STK and MATLAB platform, the process of inter-satellite laser link establishment was designed, and setting the scene of TDRS capturing and tracking user's satellite as an example, simulation was realized and demonstrated.

  9. Rotary Release Mechanism With Fusible Link

    Science.gov (United States)

    Sevilla, Donald R.; Blomquist, Richard S.

    1996-01-01

    Rotary release mechanism includes fusible rotary link made of alloy that melts at relatively low temperature of 60 degrees C. When solid, link couples driving shaft to driven shaft. When necessary, link melted to temporarily decouple two shafts. Upon cooling below melting temperature link hardens, so it once again couples two shafts. Release mechanism extremely compact alternative to pyrotechnic release device. Basic concept applied to such other mechanisms as pin pullers, pin pushers, electrical-disconnection mechanisms, and clutches.

  10. Realization of intermediate links of line arrangements

    OpenAIRE

    Bodin, Arnaud

    2012-01-01

    We investigate several topological and combinatorial properties of line arrangements. We associate to a line arrangement a link obtained by intersecting the arrangement with some sphere. Several topics are discussed: (a) some link configurations can be realized by complex line arrangements but not by real line arrangements; (b) if we intersect the arrangements with a vertical band instead of a sphere, what link configurations can be obtained? (c) relations between link configurations obtained...

  11. Microprocessor-controlled CAMAC data link module

    Energy Technology Data Exchange (ETDEWEB)

    Potter, J.M.

    1978-05-01

    Communication between the central control computer and remote, satellite data-acquisition/control stations at the Clinton P. Anderson Meson Physics Facility (LAMPF) is presently accomplished through the use of CAMAC-based Data Link modules. With the advent of the microprocessor, a new philosophy for digital data communications has evolved. Data Link modules containing microprocessor controllers provide link management and communication network protocol through algorithms executed in the Data Link microprocessor. 13 figures.

  12. Using Expert Knowledge for Test Linking

    NARCIS (Netherlands)

    Bolsinova, Maria; Hoijtink, Herbert; Vermeulen, Jorine Adinda; Béguin, Anton

    2017-01-01

    cases where no assumption of random equivalent groups can be made some form of linking design is used. In practice the amount of data available to link the two tests is often very limited due to logistic and security reasons, which affects the precision of linking procedures. This study proposes to

  13. Using Expert Knowledge for Test Linking

    NARCIS (Netherlands)

    Bolsinova, Maria|info:eu-repo/dai/nl/338038205; Hoijtink, Herbert|info:eu-repo/dai/nl/075184427; Vermeulen, Jorine Adinda; Béguin, Anton

    2017-01-01

    Linking and equating procedures are used to make the results of different test forms comparable. In the cases where no assumption of random equivalent groups can be made some form of linking design is used. In practice the amount of data available to link the two tests is often very limited due to

  14. Production and Consumption of University Linked Data

    Science.gov (United States)

    Zablith, Fouad; Fernandez, Miriam; Rowe, Matthew

    2015-01-01

    Linked Data increases the value of an organisation's data over the web by introducing explicit and machine processable links at the data level. We have adopted this new stream of data representation to produce and expose existing data within The Open University (OU) as Linked Data. We present in this paper our approach for producing the data,…

  15. Electrospinning formaldehyde cross-linked zein solutions

    Science.gov (United States)

    In order to develop zein fibers with improved physical properties and solvent resistance, formaldehyde was used as the cross-linking reagent before spinning. The cross-linking reaction was carried out in either acetic acid or ethanolic-HCl where the amount of cross-linking reagent was between 1 and...

  16. Restricted linking of emissions trading systems

    NARCIS (Netherlands)

    Schneider, Lambert; Lazarus, Michael; Lee, Carrie; Asselt, van Harro

    2017-01-01

    With over 17 emissions trading systems (ETSs) now in place across four continents, interest in linking ETSs is growing. Linking ETSs offers economic, political, and administrative benefits. It also faces major challenges. Linking can affect overall ambition, financial flows, and the location and

  17. Impact of Packet Sampling on Link Dimensioning

    NARCIS (Netherlands)

    Schmidt, R.D.O.; Sadre, R.; Sperotto, A.; Berg, H. van den; Pras, A.

    2015-01-01

    Link dimensioning is used by network operators to properly provision the capacity of their network links. Proposed methods for link dimensioning often require statistics, such as traffic variance, that need to be calculated from packet-level measurements. In practice, due to increasing traffic

  18. PIPELINES AS COMMUNICATION NETWORK LINKS

    Energy Technology Data Exchange (ETDEWEB)

    Kelvin T. Erickson; Ann Miller; E. Keith Stanek; C.H. Wu; Shari Dunn-Norman

    2005-03-14

    This report presents the results of an investigation into two methods of using the natural gas pipeline as a communication medium. The work addressed the need to develop secure system monitoring and control techniques between the field and control centers and to robotic devices in the pipeline. In the first method, the pipeline was treated as a microwave waveguide. In the second method, the pipe was treated as a leaky feeder or a multi-ground neutral and the signal was directly injected onto the metal pipe. These methods were tested on existing pipeline loops at UMR and Batelle. The results reported in this report indicate the feasibility of both methods. In addition, a few suitable communication link protocols for this network were analyzed.

  19. Property Testing on Linked Lists

    DEFF Research Database (Denmark)

    Afshani, Peyman; Matulef, Kevin; Wilkinson, Bryan Thomas

    2013-01-01

    We define a new property testing model for algorithms that do not have arbitrary query access to the input, but must instead traverse it in a manner that respects the underlying data structure in which it is stored. In particular, we consider the case when the underlying data structure is a linked...... list, and the testing algorithm is allowed to either sample randomly from the list, or walk to nodes that are adjacent to those already visited. We study the well-known monotonicity testing problem in this model, and show that (n13) queries are both necessary and sufficient to distinguish whether...... a list is sorted (monotone increasing) versus a constant distance from sorted. Our bound is strictly greater than the (logn) queries required in the standard testing model, that allows element access indexed by rank, and strictly less than the (n12) queries required by a weak model that only allows...

  20. X-linked recessive ichthyosis.

    Science.gov (United States)

    Hazan, Carole; Orlow, Seth J; Schaffer, Julie V

    2005-12-30

    A 13-year-old boy presented with a lifelong history of tightly-adherent, brown, polygonal scales that covered the extensor surfaces of the extremities, lateral aspects of the trunk, and neck. The clinical presentation and the history of a similar skin condition in the patient's male maternal relatives helped establish the diagnosis of X-linked recessive ichthyosis (XLI). Systemic manifestations of the steroid sulfatase (STS) deficiency underlying XLI include cryptorchidism, asymptomatic corneal opacities, and maternal failure to progress during labor. Most cases of XLI are caused by deletions of the STS gene, and contiguous gene syndromes may occur when the deletions extend to neighboring genes on the distal short arm of the X chromosome.

  1. Linking DC together with TRSL

    DEFF Research Database (Denmark)

    Haxthausen, Anne; Yong, Xia

    1999-01-01

    for high-level specifications of real-time requirementsand TRSL for specifying real-time implementations in the form of timed communicating concurrent processes.In order to link DC and TRSL together in a well-founded way, we formally define what it means for a TRSL process to satisfy a DC requirement...... of constraints on the durations of states of the system, i.e. at a high level of abstraction.However, as a state-based logic, it lacks the ability to specifysequential programs and communicating concurrent processes at a concrete level. The Timed RAISE Specification Language (TRSL) [XG99] has this ability.......TRSL is a real-time extension of the RAISE Specification Language (RSL) [Rlg92] which together with its associated method [Rmg95]and tools has shown to be very useful in the industrial development of software systems. Therefore, a promising approach for the development of real-time systemscould be to use DC...

  2. Whence the eigenstate-eigenvalue link?

    Science.gov (United States)

    Gilton, Marian J. R.

    2016-08-01

    David Wallace has recently argued that the eigenstate-eigenvalue (E-E) link has no place in serious discussions of quantum mechanics on the grounds that, as he claims, the E-E link is an invention of philosophers rather than the community of practicing physicists. This raises an historical question regarding the origin of the link. This paper aims to answer this question by tracing the historical development of the link through six key textbooks of quantum mechanics. In light of the historical evidence from these textbooks, it is argued that Wallace provides insufficient grounds for dismissing the E-E link from discussions of quantum mechanics.

  3. Ontology driven dynamic linking of biology resources.

    Science.gov (United States)

    Bechhofer, S K; Stevens, R D; Lord, P W

    2005-01-01

    Biologists were early adopters of the Web and continue to use it as the primary means of delivering data, tools and knowledge to their community. The Web is made by the links between pages, yet these links have many limitations: they are static and maintained by hand; they can only link one lexical item to another single resource; ownership is necessary for the placement of link anchors and the link mechanism is essentially inflexible. Dynamic linking services, supported by ontologies, offer a mechanism to overcome such restrictions. The Conceptual Open Hypermedia Service (COHSE) system enhances web resources through the dynamic addition of hypertext links. These links are derived through the use of an ontology and associated lexicon along with a mapping from concepts to possible link targets. We describe an application of COHSE to Bioinformatics, using the Gene Ontology (GO) as an ontology and associated keyword mappings and GO associations as link targets. The resulting demonstrator (referred to here as GOHSE) provides both glossary functionality and the possibility of building knowledge based hypertext structures linking bioinformatics resources.

  4. Adaptive link selection algorithms for distributed estimation

    Science.gov (United States)

    Xu, Songcen; de Lamare, Rodrigo C.; Poor, H. Vincent

    2015-12-01

    This paper presents adaptive link selection algorithms for distributed estimation and considers their application to wireless sensor networks and smart grids. In particular, exhaustive search-based least mean squares (LMS) / recursive least squares (RLS) link selection algorithms and sparsity-inspired LMS / RLS link selection algorithms that can exploit the topology of networks with poor-quality links are considered. The proposed link selection algorithms are then analyzed in terms of their stability, steady-state, and tracking performance and computational complexity. In comparison with the existing centralized or distributed estimation strategies, the key features of the proposed algorithms are as follows: (1) more accurate estimates and faster convergence speed can be obtained and (2) the network is equipped with the ability of link selection that can circumvent link failures and improve the estimation performance. The performance of the proposed algorithms for distributed estimation is illustrated via simulations in applications of wireless sensor networks and smart grids.

  5. Hacking 360 Link: A hybrid approach

    Directory of Open Access Journals (Sweden)

    John Durno

    2012-10-01

    Full Text Available When the University of Victoria Libraries switched from a locally-hosted link resolver (SFX to a vendor-hosted link resolver (360Link, new strategies were required to effectively integrate the vendor-hosted link resolver with the Libraries' other systems and services. Custom javascript is used to add links to the 360Link page; these links then point at local PHP code running on UVic servers, which can then redirect to appropriate local service or display a form directly. An open source PHP OpenURL parser class is announced. Consideration is given to the importance of maintaining open protocols and standards in the transition to vendor-hosted services.

  6. Linking Diversity and Disparity Measures

    Directory of Open Access Journals (Sweden)

    Sahadeb Sarkar

    2012-07-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} The purpose of this paper is to examine links between the diversity measures (Patil and Taillie 1982 and the disparity measures (Lindsay 1994, quantities apparently developed for somewhat different purposes. We demonstrate that numerous diversity measures satisfying all the desirable criteria mentioned by Patil and Taillie can be defined by the generating functions of certain disparities and the associated residual adjustment functions. This provides the statistician and the ecologist a wide class of flexible indices for the statistical measurement of diversity.

  7. Sirtuins Link Inflammation and Metabolism

    Directory of Open Access Journals (Sweden)

    Vidula T. Vachharajani

    2016-01-01

    Full Text Available Sirtuins (SIRT, first discovered in yeast as NAD+ dependent epigenetic and metabolic regulators, have comparable activities in human physiology and disease. Mounting evidence supports that the seven-member mammalian sirtuin family (SIRT1–7 guard homeostasis by sensing bioenergy needs and responding by making alterations in the cell nutrients. Sirtuins play a critical role in restoring homeostasis during stress responses. Inflammation is designed to “defend and mend” against the invading organisms. Emerging evidence supports that metabolism and bioenergy reprogramming direct the sequential course of inflammation; failure of homeostasis retrieval results in many chronic and acute inflammatory diseases. Anabolic glycolysis quickly induced (compared to oxidative phosphorylation for ROS and ATP generation is needed for immune activation to “defend” against invading microorganisms. Lipolysis/fatty acid oxidation, essential for cellular protection/hibernation and cell survival in order to “mend,” leads to immune repression. Acute/chronic inflammations are linked to altered glycolysis and fatty acid oxidation, at least in part, by NAD+ dependent function of sirtuins. Therapeutically targeting sirtuins may provide a new class of inflammation and immune regulators. This review discusses how sirtuins integrate metabolism, bioenergetics, and immunity during inflammation and how sirtuin-directed treatment improves outcome in chronic inflammatory diseases and in the extreme stress response of sepsis.

  8. Materializing the web of linked data

    CERN Document Server

    Konstantinou, Nikolaos

    2015-01-01

    This book explains the Linked Data domain by adopting a bottom-up approach: it introduces the fundamental Semantic Web technologies and building blocks, which are then combined into methodologies and end-to-end examples for publishing datasets as Linked Data, and use cases that harness scholarly information and sensor data. It presents how Linked Data is used for web-scale data integration, information management and search. Special emphasis is given to the publication of Linked Data from relational databases as well as from real-time sensor data streams. The authors also trace the transformation from the document-based World Wide Web into a Web of Data. Materializing the Web of Linked Data is addressed to researchers and professionals studying software technologies, tools and approaches that drive the Linked Data ecosystem, and the Web in general.

  9. Robot arm geometric link parameter estimation

    Science.gov (United States)

    Hayati, S. A.

    1983-01-01

    A general method for estimating serial link manipulator geometric parameter errors is proposed in this paper. The positioning accuracy of the end-effector may be increased significantly by updating the nominal link parameters in the control software to represent the physical system more accurately. The proposed method is applicable for serial link manipulators with any combination of revolute or prismatic joints, and is not limited to a specific measurement technique.

  10. Performance of VCSELs for SCT links

    CERN Document Server

    Mandic, I

    1998-01-01

    Vertical Cavity Surface Emitting Laser (VCSEL) diodes will be used as the light source for SCT optical links. In this note we report about measurements of electrical and optical properties of VCSELs relevant for the design of new version of driving and receiving electronics. Excellent performance was obtained already with the existing links electronics proving that VCSELs are a good light source for the SCT links. Only minor changes in driving and receiving circuitry are needed for the transition from LEDs to VCSELs.

  11. Cascade of links in complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yeqian; Sun, Bihui [Department of Management Science, School of Government, Beijing Normal University, 100875 Beijing (China); Zeng, An, E-mail: anzeng@bnu.edu.cn [School of Systems Science, Beijing Normal University, 100875 Beijing (China)

    2017-01-30

    Cascading failure is an important process which has been widely used to model catastrophic events such as blackouts and financial crisis in real systems. However, so far most of the studies in the literature focus on the cascading process on nodes, leaving the possibility of link cascade overlooked. In many real cases, the catastrophic events are actually formed by the successive disappearance of links. Examples exist in the financial systems where the firms and banks (i.e. nodes) still exist but many financial trades (i.e. links) are gone during the crisis, and the air transportation systems where the airports (i.e. nodes) are still functional but many airlines (i.e. links) stop operating during bad weather. In this letter, we develop a link cascade model in complex networks. With this model, we find that both artificial and real networks tend to collapse even if a few links are initially attacked. However, the link cascading process can be effectively terminated by setting a few strong nodes in the network which do not respond to any link reduction. Finally, a simulated annealing algorithm is used to optimize the location of these strong nodes, which significantly improves the robustness of the networks against the link cascade. - Highlights: • We propose a link cascade model in complex networks. • Both artificial and real networks tend to collapse even if a few links are initially attacked. • The link cascading process can be effectively terminated by setting a few strong nodes. • A simulated annealing algorithm is used to optimize the location of these strong nodes.

  12. Run, Walk, Crawl: Towards Dynamic Link Capacities

    DEFF Research Database (Denmark)

    Singh, Rachee; Ghobadi, Monia; Förster, Klaus-Tycho

    2017-01-01

    Fiber optic cables are the workhorses of today’s Internet services. Operators spend millions of dollars to purchase, lease and maintain their optical backbone, making the efficiency of fiber essential to their business. In this work, we make a case for adapting the capacity of optical links based...... backbone in North America. Second, at least 25% of link failures are caused by SNR degradation, not complete loss-of-light, highlighting the opportunity to replace link failures by link flaps wherein the capacity is adjusted according to the new SNR. Given these benefits, we identify the disconnect between...

  13. The capacity of digital links in tandem

    Science.gov (United States)

    Posner, E. C.; Rubin, A. L.

    1984-01-01

    The present investigation is concerned with the error control strategy used in connection with digital data networks, taking into account the capacity of the end-to-end channel. It is assumed that the only source of noise is Gaussian and that bandwidth limitation on capacity can be ignored. Attention is given to L links in tandem with binary repeaters, the asymptotic capacity with a large number of links, some alternative repeater strategies, and approaches for lowering the bit error probability. Numerical results are presented, taking into consideration capacity versus link error probability for various numbers of links.

  14. LINKING STATE, UNIVERSITY AND BUSINESS IN NICARAGUA

    Directory of Open Access Journals (Sweden)

    Máximo Andrés Rodríguez Pérez

    2015-07-01

    Full Text Available In Nicaragua levels Linking state, university and business are low, Nicaraguan universities have initiated communication strategies with the state and the private sector. The idiosyncrasies of its citizens favor this link. The entailment policies formalize the communications and information networks. Universities have a key role in building models and organizations that provide alternatives to economic development. Linking the university with the environment, generating virtuous circles, where companies achieve greater competitiveness, the state, higher taxes and public stability, universities generate new knowledge. This article analyzes the strategies linking U-E- E that can be applied in Nicaragua, to strengthen and achieve positive developments in the country.

  15. A novel method for combating dispersion induced power fading in dispersion compensating fiber

    DEFF Research Database (Denmark)

    Lebedev, Alexander; Vegas Olmos, Juan José; Iglesias Olmedo, Miguel

    2013-01-01

    We experimentally investigate the performance of 60 GHz double sideband (DSB) radio over fiber (RoF) links that employ dispersion compensating fiber (DCF). Error free transmission of 3 Gbps signals over 1 m of wireless distance is reported. In order to overcome experimentally observed chromatic...... dispersion (CD) induced power fading of radio frequency (RF) signal, we propose a method for improvement of RF carrier-to-noise (C/N) ratio through introduction of a degree of RF frequency tunability. Overall results improve important aspects of directly modulated RoF systems and demonstrate the feasibility...... of high carrier frequency and wide bandwidth RF signals delivery in RoF links including DCF fiber. Error free performance that we obtain for 3 Gbps amplitude shift-keying (ASK) signals enables uncompressed high-definition 1080p video delivery....

  16. Rainfall measurement using cell phone links

    NARCIS (Netherlands)

    Schip, van het T.I.; Overeem, A.; Leijnse, H.; Uijlenhoet, R.; Meirink, J.F.; Delden, van A.J.

    2017-01-01

    Commercial cellular telecommunication networks can be used for rainfall estimation by measuring the attenuation of electromagnetic signals transmitted between antennas from microwave links. However, as the received link signal may also decrease during dry periods, a method to separate wet and dry

  17. Linking Poverty, Irregular Migration and Human Trafficking ...

    African Journals Online (AJOL)

    Migration literature suggests that poverty, irregular migration and human trafficking are causally linked. However, empirical studies linking these aspects of migration are scarce. This is because, as clandestine activities, data collection on these aspects of migration presents serious challenges. As a result of these ...

  18. Exploring the obesity-asthma link

    DEFF Research Database (Denmark)

    Fenger, R V; Gonzalez-Quintela, A; Vidal, C

    2012-01-01

    Obesity and risk of asthma are linked. Different distributions of adiposity, such as visceral, subcutaneous or ectopic adiposity, may affect asthma risk differently.......Obesity and risk of asthma are linked. Different distributions of adiposity, such as visceral, subcutaneous or ectopic adiposity, may affect asthma risk differently....

  19. Biosimilars : linking quality data to clinical outcomes

    NARCIS (Netherlands)

    Halim, L.A.

    2016-01-01

    The aim of this study was to establish a link between quality attributes of biosimilars and potential clinical outcomes with regards to safety and immunogenicity. As we have access to multiple biosimilar and copy biologic products as well to patient data, the research involved linking comparative

  20. Using linked data in Learning Analytics

    NARCIS (Netherlands)

    Mathieu, d'Aquin; Stefan, Dietze; Eelco, Herder; Hendrik, Drachsler; Davide, Taibi

    2014-01-01

    d’Aquin, M., Dietze, S., Herder, E., Drachsler, H., & Taibi, D. (2014). Using linked data in learning analytics. eLearning Papers. Nr. 36/2. ISSN: 1887-1542. http://www.openeducationeuropa.eu/en/article/Using-linked-data-in-Learning-Analytics?paper=134810

  1. Fast Link Adaptation for MIMO-OFDM

    DEFF Research Database (Denmark)

    Jensen, Tobias Lindstrøm; Kant, Shashi; Wehinger, Joachim

    2010-01-01

    We investigate link-quality metrics (LQMs) based on raw bit-error-rate, effective signal-to-interference-plus-noise ratio, and mutual information (MI) for the purpose of fast link adaptation (LA) in communication systems employing orthogonal frequency-division multiplexing and multiple...

  2. Chemical cross-linking of Chlamydia trachomatis

    DEFF Research Database (Denmark)

    Birkelund, Svend; Lundemose, AG; Christiansen, Gunna

    1988-01-01

    Purified elementary bodies (EBs) of Chlamydia trachomatis serovar L2 were analyzed by chemical cross-linking with disuccinimidyl selenodipropionate. The effect of the cross-linking was analyzed by immunoblotting sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated components which...

  3. Dutch Ships and Sailors Linked Data

    NARCIS (Netherlands)

    de Boer, Victor; Leinenga, Jurjen; Hoekstra, F.G.; van Rossum, Matthias; Mika, Peter; Tudorache, Tadia; Bernstein, Abraham

    2014-01-01

    We present the Dutch Ships and Sailors Linked Data Cloud. This heterogeneous dataset brings together four curated datasets on Dutch Maritime history as five-star linked data. The individual datasets use separate datamodels, designed in close collaboration with maritime historical researchers. The

  4. Wireless link design using a patch antenna

    Energy Technology Data Exchange (ETDEWEB)

    Hall, E

    2000-08-11

    A wireless link was designed using a patch antenna. In the process, several different models were tested. Testing proved a patch antenna was a viable solution for building a wireless link within the design specifications. Also, this experimentation provided a basis for future patch antenna design.

  5. The Versatile Link Demo Board (VLDB)

    Science.gov (United States)

    Martín Lesma, R.; Alessio, F.; Barbosa, J.; Baron, S.; Caplan, C.; Leitao, P.; Pecoraro, C.; Porret, D.; Wyllie, K.

    2017-02-01

    The Versatile Link Demonstrator Board (VLDB) is the evaluation kit for the radiation-hard Optical Link ecosystem, which provides a 4.8 Gbps data transfer link for communication between front-end (FE) and back-end (BE) of the High Energy Physics experiments. It gathers the Versatile link main radiation-hard custom Application-Specific Integrated Circuits (ASICs) and modules: GBTx, GBT-SCA and VTRx/VTTx plus the FeastMP, a radiation-hard in-house designed DC-DC converter. This board is the first design allowing system-level tests of the Link with a complete interconnection of the constitutive components, allowing data acquisition, control and monitoring of FE devices with the GBT-SCA pair.

  6. Molecular Mechanics of Tip-Link Cadherins

    Science.gov (United States)

    Sotomayor, Marcos; Weihofen, Wilhelm A.; Gaudet, Rachelle; Corey, David P.

    2011-11-01

    The hair-cell tip link, a fine filament directly conveying force to mechanosensitive transduction channels, is likely composed of two proteins, protocadherin-15 and cadherin-23, whose mutation causes deafness. However, their complete molecular structure, elasticity, and deafness-related structural defects remain largely unknown. We present crystal structures of extracellular (EC) tip-link cadherin repeats involved in hereditary deafness and tip link formation. In addition, we show that the deafness mutation D101G, in the linker region between the repeats EC1 and EC2 of cadherin-23, causes a slight bend between repeats and decreases Ca2+ affinity. Molecular dynamics simulations suggest that tip-link cadherin repeats are stiff and that either removing Ca2+ or mutating Ca2+-binding residues reduces rigidity and unfolding strength. The structures and simulations also suggest mechanisms underlying inherited deafness and how cadherin-23 may bind with protocadherin-15 to form the tip link.

  7. Propagation engineering in radio links design

    CERN Document Server

    Ghasemi, Abdollah; Ghasemi, Farshid

    2013-01-01

    Propagation Engineering in Radio Link Design covers the basic principles of radiowaves propagation in a practical manner.  This fundamental understanding enables the readers to design radio links efficiently. This book elaborates on new achievements as well as recently developed propagation models.  This is in addition to a comprehensive overview of fundamentals of propagation in various scenarios. It examines theoretical calculations, approaches and applied procedures needed for radio links design. The authors study and analysis of the main propagation phenomena and its mechanisms based on the recommendations of International Telecommunications Union, (ITU). The book has been organized in 9 chapters and examines the role of antennas and passive reflectors in radio services, propagation mechanisms related to radar, satellite, short distance, broadcasting and trans-horizon radio links, with two chapters devoted to radio noise and main  parameters of radio link design. The book presents some 278 illustration...

  8. Mapping the x-linked lymphoproliferative syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Skare, J.C.; Milunsky, A.; Byron, K.S.; Sullivan, J.L.

    1987-04-01

    The X-linked lymphoproliferative syndrome is triggered by Epstein-Barr virus infection and results in fatal mononucleosis, immunodeficiency, and lymphoproliferative disorders. This study shows that the mutation responsible for X-linked lymphoproliferative syndrome is genetically linked to a restriction fragment length polymorphism detected with the DXS42 probe (from Xq24-q27). The most likely recombination frequency between the loci is 4%, and the associated logarithm of the odds is 5.26. Haplotype analysis using flanking restriction fragment length polymorphism markers indicates that the locus for X-linked lymphoproliferative syndrome is distal to probe DXS42 but proximal to probe DXS99 (from Xq26-q27). It is now possible to predict which members of a family with X-linked lymphoproliferative syndrome are carrier females and to diagnose the syndrome prenatally.

  9. Missing and forbidden links in mutualistic networks.

    Science.gov (United States)

    Olesen, Jens M; Bascompte, Jordi; Dupont, Yoko L; Elberling, Heidi; Rasmussen, Claus; Jordano, Pedro

    2011-03-07

    Ecological networks are complexes of interacting species, but not all potential links among species are realized. Unobserved links are either missing or forbidden. Missing links exist, but require more sampling or alternative ways of detection to be verified. Forbidden links remain unobservable, irrespective of sampling effort. They are caused by linkage constraints. We studied one Arctic pollination network and two Mediterranean seed-dispersal networks. In the first, for example, we recorded flower-visit links for one full season, arranged data in an interaction matrix and got a connectance C of 15 per cent. Interaction accumulation curves documented our sampling of interactions through observation of visits to be robust. Then, we included data on pollen from the body surface of flower visitors as an additional link 'currency'. This resulted in 98 new links, missing from the visitation data. Thus, the combined visit-pollen matrix got an increased C of 20 per cent. For the three networks, C ranged from 20 to 52 per cent, and thus the percentage of unobserved links (100 - C) was 48 to 80 per cent; these were assumed forbidden because of linkage constraints and not missing because of under-sampling. Phenological uncoupling (i.e. non-overlapping phenophases between interacting mutualists) is one kind of constraint, and it explained 22 to 28 per cent of all possible, but unobserved links. Increasing phenophase overlap between species increased link probability, but extensive overlaps were required to achieve a high probability. Other kinds of constraint, such as size mismatch and accessibility limitations, are briefly addressed.

  10. Porous Cross-Linked Polyimide Networks

    Science.gov (United States)

    Meador, Mary Ann B. (Inventor); Guo, Haiquan (Inventor)

    2015-01-01

    Porous cross-linked polyimide networks are provided. The networks comprise an anhydride end-capped polyamic acid oligomer. The oligomer (i) comprises a repeating unit of a dianhydride and a diamine and terminal anhydride groups, (ii) has an average degree of polymerization of 10 to 50, (iii) has been cross-linked via a cross-linking agent, comprising three or more amine groups, at a balanced stoichiometry of the amine groups to the terminal anhydride groups, and (iv) has been chemically imidized to yield the porous cross-linked polyimide network. Also provided are porous cross-linked polyimide aerogels comprising a cross-linked and imidized anhydride end-capped polyamic acid oligomer, wherein the oligomer comprises a repeating unit of a dianhydride and a diamine, and the aerogel has a density of 0.10 to 0.333 g/cm.sup.3 and a Young's modulus of 1.7 to 102 MPa. Also provided are thin films comprising aerogels, and methods of making porous cross-linked polyimide networks.

  11. Web Applications of Bibliometrics and Link Analysis

    Directory of Open Access Journals (Sweden)

    Faribourz Droudi

    2010-04-01

    Full Text Available The present study aims to introduce and analyze bibliometric application within Web and also to expounds on the status of link analysis in order to point out its application with respect to the existing web-based information sources. Findings indicate that bibliometrics could have required application in the area of digital resources available through Net. Link analysis is a process by which one could make statistical analysis of correlation between hyperlinks and therefore understand the accuracy, veracity and efficacy of citations within a digital document. Link analysis, in effect, is counted as a part of information ranking algorithm within the web environment. The number, linkage and quality of given links to a website are of utmost importance for ranking/status in the Web. The tools applied in this topic include, page ranking strategy, link analysis algorithm, latent semantic indexing and the classical input-output model. The present study analyzes Big Web and Small Web link analysis and explains the means for utilizing web charts in order to better understand the link analysis process.

  12. The Gigabit Link Interface Board (GLIB) ecosystem

    CERN Document Server

    Vichoudis, P; Baron, S; Barros Marin, M; Bobillier, V; Chramowitz, J; Haas, S; Hansen, M; Joos, M; Lobato Pardavila, L; Petit, P; Prosser, A; Vasey, F

    2013-01-01

    The Gigabit Link Interface Board (GLIB) project is an FPGA-based platform for users of high-speed optical links in high energy physics experiments. The major hardware component of the platform is the GLIB Advanced Mezzanine Card (AMC). Additionally to the AMC, auxiliary components are developed that enhance GLIB platform's I/O bandwidth and compatibility with legacy and future triggering and/or data acquisition interfaces. This article focuses on the development of the auxiliary components that together with the GLIB AMC offer a complete solution for beam/irradiation tests of detector modules and evaluation of optical links.

  13. Homfly Polynomials of Generalized Hopf Links

    OpenAIRE

    Morton, Hugh R.; Hadji, Richard J.

    2001-01-01

    Following the recent work by T.-H. Chan in [HOMFLY polynomial of some generalized Hopf links, J. Knot Theory Ramif. 9 (2000) 865--883] on reverse string parallels of the Hopf link we give an alternative approach to finding the Homfly polynomials of these links, based on the Homfly skein of the annulus. We establish that two natural skein maps have distinct eigenvalues, answering a question raised by Chan, and use this result to calculate the Homfly polynomial of some more general reverse stri...

  14. Link mining models, algorithms, and applications

    CERN Document Server

    Yu, Philip S; Faloutsos, Christos

    2010-01-01

    This book presents in-depth surveys and systematic discussions on models, algorithms and applications for link mining. Link mining is an important field of data mining. Traditional data mining focuses on 'flat' data in which each data object is represented as a fixed-length attribute vector. However, many real-world data sets are much richer in structure, involving objects of multiple types that are related to each other. Hence, recently link mining has become an emerging field of data mining, which has a high impact in various important applications such as text mining, social network analysi

  15. Linking Libraries to the Web: Linked Data and the Future of the Bibliographic Record

    Directory of Open Access Journals (Sweden)

    Brighid M. Gonzales

    2014-12-01

    Full Text Available The ideas behind Linked Data and the Semantic Web have recently gained ground and shown the potential to redefine the world of the web. Linked Data could conceivably create a huge database out of the internet, linked by relationships understandable by both humans and machines. The benefits of Linked Data to libraries and their users are potentially great, but so are the many challenges to its implementation. The BIBFRAME Initiative provides the possible framework that will link library resources with the web, bringing them out of their information silos and making them accessible to all users.

  16. Linking Medicare, Medicaid, and Cancer Registry Data...

    Data.gov (United States)

    U.S. Department of Health & Human Services — Linking Medicare, Medicaid, and Cancer Registry Data to Study the Burden of Cancers in West Virginia In the United States, the elderly carry an unequal burden of...

  17. Gut Microbes Linked to Rheumatoid Arthritis

    Science.gov (United States)

    ... Matters November 25, 2013 Gut Microbes Linked to Rheumatoid Arthritis The presence of a specific type of gut bacteria correlates with rheumatoid arthritis in newly diagnosed, untreated people. The finding suggests ...

  18. Prenatal Inflammation Linked to Autism Risk

    Science.gov (United States)

    ... Thursday, January 24, 2013 Prenatal inflammation linked to autism risk Maternal inflammation during early pregnancy may be related to an increased risk of autism in children, according to new findings supported by ...

  19. Benchmarking Linked Open Data Management Systems

    NARCIS (Netherlands)

    R. Angles Rojas (Renzo); M.-D. Pham (Minh-Duc); P.A. Boncz (Peter)

    2014-01-01

    htmlabstractWith inherent support for storing and analysing highly interconnected data, graph and RDF databases appear as natural solutions for developing Linked Open Data applications. However, current benchmarks for these database technologies do not fully attain the desirable characteristics

  20. Improving Machine Translation through Linked Data

    Directory of Open Access Journals (Sweden)

    Srivastava Ankit

    2017-06-01

    Full Text Available With the ever increasing availability of linked multilingual lexical resources, there is a renewed interest in extending Natural Language Processing (NLP applications so that they can make use of the vast set of lexical knowledge bases available in the Semantic Web. In the case of Machine Translation, MT systems can potentially benefit from such a resource. Unknown words and ambiguous translations are among the most common sources of error. In this paper, we attempt to minimise these types of errors by interfacing Statistical Machine Translation (SMT models with Linked Open Data (LOD resources such as DBpedia and BabelNet. We perform several experiments based on the SMT system Moses and evaluate multiple strategies for exploiting knowledge from multilingual linked data in automatically translating named entities. We conclude with an analysis of best practices for multilingual linked data sets in order to optimise their benefit to multilingual and cross-lingual applications.

  1. CULTURAL LINK ANALYSIS OF JAPANESE AMERICANS

    National Research Council Canada - National Science Library

    Yamaoka, Kazue; Hayashi, Chikio

    2003-01-01

    Using survey results of Japanese Americans (JA) living on the West Coast of the USA in 1998, and JA and non-JA living in Hawaii in 1999-2000, we examined cultural links between native Japanese, JAs, and Americans...

  2. Highly cross-linked nanoporous polymers

    Science.gov (United States)

    Steckle, Jr., Warren P.; Apen, Paul G.; Mitchell, Michael A.

    1997-01-01

    Condensation polymerization followed by a supercritical extraction step can be used to obtain highly cross-linked nanoporous polymers with high surface area, controlled pore sizes and rigid structural integrity. The invention polymers are useful for applications requiring separation membranes.

  3. Link prediction via generalized coupled tensor factorisation

    DEFF Research Database (Denmark)

    Ermiş, Beyza; Evrim, Acar Ataman; Taylan Cemgil, A.

    2012-01-01

    This study deals with the missing link prediction problem: the problem of predicting the existence of missing connections between entities of interest. We address link prediction using coupled analysis of relational datasets represented as heterogeneous data, i.e., datasets in the form of matrices...... and higher-order tensors. We propose to use an approach based on probabilistic interpretation of tensor factorisation models, i.e., Generalised Coupled Tensor Factorisation, which can simultaneously fit a large class of tensor models to higher-order tensors/matrices with com- mon latent factors using...... different loss functions. Numerical experiments demonstrate that joint analysis of data from multiple sources via coupled factorisation improves the link prediction performance and the selection of right loss function and tensor model is crucial for accurately predicting missing links....

  4. Nonequilibrium Chromosome Looping via Molecular Slip Links

    Science.gov (United States)

    Brackley, C. A.; Johnson, J.; Michieletto, D.; Morozov, A. N.; Nicodemi, M.; Cook, P. R.; Marenduzzo, D.

    2017-09-01

    We propose a model for the formation of chromatin loops based on the diffusive sliding of molecular slip links. These mimic the behavior of molecules like cohesin, which, along with the CTCF protein, stabilize loops which contribute to organizing the genome. By combining 3D Brownian dynamics simulations and 1D exactly solvable nonequilibrium models, we show that diffusive sliding is sufficient to account for the strong bias in favor of convergent CTCF-mediated chromosome loops observed experimentally. We also find that the diffusive motion of multiple slip links along chromatin is rectified by an intriguing ratchet effect that arises if slip links bind to the chromatin at a preferred "loading site." This emergent collective behavior favors the extrusion of loops which are much larger than the ones formed by single slip links.

  5. Tutorial: Linking content in unstructured sources

    OpenAIRE

    Moens, Marie-Francine

    2010-01-01

    This tutorial focuses on the task of automated information linking in text and multimedia sources. In any task where information is fused from different sources, this linking is a necessary step. To solve the problem we borrow methods from computational linguistics, computer vision and data mining. Although the main focus is on finding equivalence relations in the sources, the tutorial opens views on the recognition of other relation types.

  6. Diabetes and gastric cancer: The potential links

    OpenAIRE

    Tseng, Chin-Hsiao; Tseng, Farn-Hsuan

    2014-01-01

    This article reviews the epidemiological evidence linking diabetes and gastric cancer and discusses some of the potential mechanisms, confounders and biases in the evaluation of such an association. Findings from four meta-analyses published from 2011 to 2013 suggest a positive link, which may be more remarkable in females and in the Asian populations. Putative mechanisms may involve shared risk factors, hyperglycemia, Helicobacter pylori (H. pylori) infection, high salt intake, medications a...

  7. The political dimension of "linking social capital"

    DEFF Research Database (Denmark)

    Rubin, Olivier

    2016-01-01

    This article sets out to improve our analytical understanding of the concept of “linking social capital.” Concretely, the article focuses on disaster contexts where the importance of linking social capital intensifies both for the vulnerable communities and for the local authorities concerned...... facilitate a more nuanced understanding of the potential risks inherent in the relationships between local authorities and communities in disaster settings....

  8. Network Communication by Optical Directional Link

    Directory of Open Access Journals (Sweden)

    V. Biolkova

    1999-04-01

    Full Text Available In this article, infrared point-to-point technologies (optical directional links are discussed which are designed for digital transmissions. Optical directional links (ODLs are transparent for the SDH/ATM, FDDI-II, Ethernet, and Token Ring protocols. Depending on type, ODL ranges are 300 m, 500 m, 1000 m and 2000 m. Steady and statistical models of ODL are presented as well as the measuring ODL arrangement and the graphs concerning the fluctuations of the received signal.

  9. Recommender Systems based on Linked Data

    OpenAIRE

    Cristhian, Figueroa

    2017-01-01

    Backgrounds: The increase in the amount of structured data published using the principles of Linked Data, means that now it is more likely to find resources in the Web of Data that describe real life concepts. However, discovering resources related to any given resource is still an open research area. This thesis studies Recommender Systems (RS) that use Linked Data as a source for generating recommendations exploiting the large amount of available resources and the relationships among them. ...

  10. Microwaves photonic links components and circuits

    CERN Document Server

    Rumelhard, Christian; Billabert, Anne-Laure

    2013-01-01

    This book presents the electrical models for the different elements of a photonic microwave link like lasers, external modulators, optical fibers, photodiodes and phototransistors. The future trends of these components are also introduced: lasers to VCSEL, external modulators to electro-absorption modulators, glass optical fibers to plastic optical fibers, photodiodes to UTC photodiodes or phototransistors. It also describes an original methodology to evaluate the performance of a microwave photonic link, based on the developed elcetrical models, that can be easily incorporated in

  11. Musical Preferences are Linked to Cognitive Styles

    OpenAIRE

    Greenberg, David M.; Simon Baron-Cohen; Stillwell, David J.; Michal Kosinski; Rentfrow, Peter J.

    2015-01-01

    Why do we like the music we do? Research has shown that musical preferences and personality are linked, yet little is known about other influences on preferences such as cognitive styles. To address this gap, we investigated how individual differences in musical preferences are explained by the empathizing-systemizing (E-S) theory. Study 1 examined the links between empathy and musical preferences across four samples. By reporting their preferential reactions to musical stimuli, samples 1 and...

  12. Emerging semantics to link phenotype and environment.

    Science.gov (United States)

    Thessen, Anne E; Bunker, Daniel E; Buttigieg, Pier Luigi; Cooper, Laurel D; Dahdul, Wasila M; Domisch, Sami; Franz, Nico M; Jaiswal, Pankaj; Lawrence-Dill, Carolyn J; Midford, Peter E; Mungall, Christopher J; Ramírez, Martín J; Specht, Chelsea D; Vogt, Lars; Vos, Rutger Aldo; Walls, Ramona L; White, Jeffrey W; Zhang, Guanyang; Deans, Andrew R; Huala, Eva; Lewis, Suzanna E; Mabee, Paula M

    2015-01-01

    Understanding the interplay between environmental conditions and phenotypes is a fundamental goal of biology. Unfortunately, data that include observations on phenotype and environment are highly heterogeneous and thus difficult to find and integrate. One approach that is likely to improve the status quo involves the use of ontologies to standardize and link data about phenotypes and environments. Specifying and linking data through ontologies will allow researchers to increase the scope and flexibility of large-scale analyses aided by modern computing methods. Investments in this area would advance diverse fields such as ecology, phylogenetics, and conservation biology. While several biological ontologies are well-developed, using them to link phenotypes and environments is rare because of gaps in ontological coverage and limits to interoperability among ontologies and disciplines. In this manuscript, we present (1) use cases from diverse disciplines to illustrate questions that could be answered more efficiently using a robust linkage between phenotypes and environments, (2) two proof-of-concept analyses that show the value of linking phenotypes to environments in fishes and amphibians, and (3) two proposed example data models for linking phenotypes and environments using the extensible observation ontology (OBOE) and the Biological Collections Ontology (BCO); these provide a starting point for the development of a data model linking phenotypes and environments.

  13. Emerging semantics to link phenotype and environment

    Directory of Open Access Journals (Sweden)

    Anne E. Thessen

    2015-12-01

    Full Text Available Understanding the interplay between environmental conditions and phenotypes is a fundamental goal of biology. Unfortunately, data that include observations on phenotype and environment are highly heterogeneous and thus difficult to find and integrate. One approach that is likely to improve the status quo involves the use of ontologies to standardize and link data about phenotypes and environments. Specifying and linking data through ontologies will allow researchers to increase the scope and flexibility of large-scale analyses aided by modern computing methods. Investments in this area would advance diverse fields such as ecology, phylogenetics, and conservation biology. While several biological ontologies are well-developed, using them to link phenotypes and environments is rare because of gaps in ontological coverage and limits to interoperability among ontologies and disciplines. In this manuscript, we present (1 use cases from diverse disciplines to illustrate questions that could be answered more efficiently using a robust linkage between phenotypes and environments, (2 two proof-of-concept analyses that show the value of linking phenotypes to environments in fishes and amphibians, and (3 two proposed example data models for linking phenotypes and environments using the extensible observation ontology (OBOE and the Biological Collections Ontology (BCO; these provide a starting point for the development of a data model linking phenotypes and environments.

  14. W-band OFDM photonic vector signal generation employing a single Mach-Zehnder modulator and precoding.

    Science.gov (United States)

    Xiao, Jiangnan; Li, Xinying; Xu, Yuming; Zhang, Ziran; Chen, Long; Yu, Jianjun

    2015-09-07

    We present a simple radio-over-fiber (RoF) link architecture for millimeter-wave orthogonal frequency division multiplexing (OFDM) transmission using only one Mach-Zehnder modulator (MZM) and precoding technique. In the transmission system, the amplitudes and the phase of the driving radio-frequency (RF) OFDM signal on each sub-carrier are precoded, to ensure that the OFDM signal after photodetector (PD) can be restored to original OFDM signal. The experimental results show that the bit-error ratios (BERs) of the transmission system are less than the forward-error-correction (FEC) threshold of 3.8 × 10(-3), which demonstrates that the generation of OFDM vector signal based on our proposed scheme can be employed in our system architecture.

  15. MIMO-OFDM WDM PON with DM-VCSEL for femtocells application.

    Science.gov (United States)

    Othman, M B; Deng, Lei; Pang, Xiaodan; Caminos, J; Kozuch, W; Prince, K; Yu, Xianbin; Jensen, Jesper Bevensee; Monroy, I Tafur

    2011-12-12

    We report on experimental demonstration of 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20 km WDM-PON with directly modulated (DM) VCSELs for femtocells application. MIMO-OFDM algorithms effectively compensate for impairments in the wireless link. Error-free signal demodulation of 64 subcarrier 4-QAM signals modulated at 198.5 Mb/s net data rate is achieved after fiber and 2 m indoor wireless transmission. We report BER of 7x10(-3) at the receiver for 16-QAM signals modulated at 397 Mb/s after 1 m of wireless transmission. Performance dependence on different wireless transmission path lengths, antenna separation, and number of subcarriers have been investigated. © 2011 Optical Society of America

  16. FTTA System Demo Using Optical Fiber-Coupled Active Antennas

    Directory of Open Access Journals (Sweden)

    Niels Neumann

    2014-08-01

    Full Text Available The convergence of optical and wireless systems such as Radio-over-Fiber (RoF networks is the key to coping with the increasing bandwidth demands due to the increasing popularity of video and other high data rate applications. A high level of integration of optical technologies enables simple base stations with a fiber-to-the-antenna (FTTA approach. In this paper, we present a complete full-duplex RoF–FTTA system consisting of integrated active fiber-coupled optical receiving and transmitting antennas that are directly connected to a standard single mode fiber optical link. Data rates up to 1 Gbit/s could be shown without advanced modulation formats on a 1.5 GHz carrier frequency. The antennas as well as the whole system are explained and the results of the system experiments are discussed.

  17. Link Analysis in the Mission Planning Lab

    Science.gov (United States)

    McCarthy, Jessica A.; Cervantes, Benjamin W.; Daugherty, Sarah C.; Arroyo, Felipe; Mago, Divyang

    2011-01-01

    The legacy communications link analysis software currently used at Wallops Flight Facility involves processes that are different for command destruct, radar, and telemetry. There is a clear advantage to developing an easy-to-use tool that combines all the processes in one application. Link Analysis in the Mission Planning Lab (MPL) uses custom software and algorithms integrated with Analytical Graphics Inc. Satellite Toolkit (AGI STK). The MPL link analysis tool uses pre/post-mission data to conduct a dynamic link analysis between ground assets and the launch vehicle. Just as the legacy methods do, the MPL link analysis tool calculates signal strength and signal- to-noise according to the accepted processes for command destruct, radar, and telemetry assets. Graphs and other custom data are generated rapidly in formats for reports and presentations. STK is used for analysis as well as to depict plume angles and antenna gain patterns in 3D. The MPL has developed two interfaces with the STK software (see figure). The first interface is an HTML utility, which was developed in Visual Basic to enhance analysis for plume modeling and to offer a more user friendly, flexible tool. A graphical user interface (GUI) written in MATLAB (see figure upper right-hand corner) is also used to quickly depict link budget information for multiple ground assets. This new method yields a dramatic decrease in the time it takes to provide launch managers with the required link budgets to make critical pre-mission decisions. The software code used for these two custom utilities is a product of NASA's MPL.

  18. Wallops Low Elevation Link Analysis for the Constellation Launch/Ascent Links

    Science.gov (United States)

    Cheung, Keith; Ho, C.; Kantak, A.; Lee, C.; Tye, R.; Richards, E.; Sham, C.; Schlesinger, A.; Barritt, B.

    2011-01-01

    To execute the President's Vision for Space Exploration, the Constellation Program (CxP) was formed to build the next generation spacecraft Orion and launch vehicles Ares, to transport human and cargo to International Space Station (ISS), moon, and Mars. This paper focuses on the detailed link analysis for Orion/Ares s launch and ascent links with Wallops 11.3m antenna (1) Orion's Dissimilar Voice link: 10.24 Kbps, 2-way (2) Ares Developmental Flight Instrument link, 20 Mbps, downlink. Three launch trajectories are considered: TD7-E, F (Feb), and G (Aug). In certain launch scenarios, the critical events of main engine cutoff (MECO) and Separation occur during the low elevation regime of WFF s downrange -- less than 5 degree elevation angle. The goal of the study is to access if there is enough link margins for WFF to track the DV and DFI links.

  19. Link!: Potential Field Guidance Algorithm for In-Flight Linking of Multi-Rotor Aircraft

    Science.gov (United States)

    Cooper, John R.; Rothhaar, Paul M.

    2017-01-01

    Link! is a multi-center NASA e ort to study the feasibility of multi-aircraft aerial docking systems. In these systems, a group of vehicles physically link to each other during flight to form a larger ensemble vehicle with increased aerodynamic performance and mission utility. This paper presents a potential field guidance algorithm for a group of multi-rotor vehicles to link to each other during flight. The linking is done in pairs. Each vehicle first selects a mate. Then the potential field is constructed with three rules: move towards the mate, avoid collisions with non-mates, and stay close to the rest of the group. Once a pair links, they are then considered to be a single vehicle. After each pair is linked, the process repeats until there is only one vehicle left. The paper contains simulation results for a system of 16 vehicles.

  20. A novel time series link prediction method: Learning automata approach

    Science.gov (United States)

    Moradabadi, Behnaz; Meybodi, Mohammad Reza

    2017-09-01

    Link prediction is a main social network challenge that uses the network structure to predict future links. The common link prediction approaches to predict hidden links use a static graph representation where a snapshot of the network is analyzed to find hidden or future links. For example, similarity metric based link predictions are a common traditional approach that calculates the similarity metric for each non-connected link and sort the links based on their similarity metrics and label the links with higher similarity scores as the future links. Because people activities in social networks are dynamic and uncertainty, and the structure of the networks changes over time, using deterministic graphs for modeling and analysis of the social network may not be appropriate. In the time-series link prediction problem, the time series link occurrences are used to predict the future links In this paper, we propose a new time series link prediction based on learning automata. In the proposed algorithm for each link that must be predicted there is one learning automaton and each learning automaton tries to predict the existence or non-existence of the corresponding link. To predict the link occurrence in time T, there is a chain consists of stages 1 through T - 1 and the learning automaton passes from these stages to learn the existence or non-existence of the corresponding link. Our preliminary link prediction experiments with co-authorship and email networks have provided satisfactory results when time series link occurrences are considered.