Development of a dc-ac power conditioner for wind generator by using neural network

This project present of development single phase DC-AC converter for wind generator application. The mathematical model of the wind generator and Artificial Neural Network control for DC-AC converter is derived. The controller is designed to stabilize the output voltage of DC-AC converter. To verify the effectiveness of the proposal controller, both simulation and experimental are developed. The simulation and experimental result show that the amplitude of output voltage of the DC-AC converter can be controlled

Future benefits and applications of intelligent on-board processing to VSAT services

The trends and roles of VSAT services in the year 2010 time frame are examined based on an overall network and service model for that period. An estimate of the VSAT traffic is then made and the service and general network requirements are identified. In order to accommodate these traffic needs, four satellite VSAT architectures based on the use of fixed or scanning multibeam antennas in conjunction with IF switching or onboard regeneration and baseband processing are suggested. The performance of each of these architectures is assessed and the key enabling technologies are identified

Data transmissions through HFC return channels

Master'sMASTER OF ENGINEERIN

Coherence-Multiplexed Optical RF Feeder Networks

An optical RF feeding system for wireless access is proposed, in which the radio access points are distinguished by means of coherence multiplexing (CM). CM is a rather unknown and potentially inexpensive optical code division multiple access technique, which is particularly suitable for relatively short-range applications with moderate transmission bandwidth requirements. Subcarrier multiplexing (SCM) can possibly be used on top of CM, either as single-channel or multichannel SCM. The performances of the resulting distribution networks are analyzed, incorporating the effect of chromatic dispersion, optical beat noise, shot noise, thermal noise, and—in the case of multichannel SCM—intermodulation distortion. The results of the IEEE 802.11b standard for wireless LAN.\u

Design of a 12-GHz multicarrier earth-terminal for satellite-CATV interconnection

The design and development of the front-end for a multi-carrier system that allows multiplex signal transmission from satellite-borne transponders is described. Detailed systems analyses provided down-converter specifications. The 12 GHz carrier down-converter uses waveguide, coaxial, and microstrip transmission line elements in its implementation. Mixing is accomplished in a single-ended coaxial mixer employing a field-replacable cartridge style diode

Delta-Sigma Digitization and Optical Coherent Transmission of DOCSIS 3.1 Signals in Hybrid Fiber Coax Networks

We first demonstrate delta-sigma digitization and coherent transmission of data over cable system interface specification (DOCSIS) 3.1 signals in a hybrid fiber coax (HFC) network. Twenty 192-MHz DOCSIS 3.1 channels with modulation up to 16384QAM are digitized by a low-pass cascade resonator feedback (CRFB) delta-sigma analog-to-digital converter (ADC) and transmitted over 80 km fiber using coherent single-λ 128-Gb/s dual-polarization (DP)-QPSK and 256-Gb/s DP-16QAM optical links. Both one-bit and two-bit delta-sigma digitization are implemented and supported by the QPSK and 16QAM coherent transmission systems, respectively. To facilitate its practical application in access networks, the coherent system is built using a low-cost narrowband optical modulator and RF amplifiers. Modulation error ratio (MER) larger than 50 dB is successfully demonstrated for all 20 DOCSIS 3.1 channels, and high order modulation up to 16384QAM is delivered over fiber for the first time in HFC networks. The raw DOCSIS data capacity is 54 Gb/s with net user information ~45 Gb/s. Moreover, the bit error ratio (BER) tolerance is evaluated by measuring the MER performance as BER increases. Negligible MER degradation is observed for BER up to 1.5 × 10−6 and 1.7 × 10−4, for one-bit and two-bit digitization, respectively

Two-layer LMDS system architecture: DAVIC-based approach and analysis

Despite the growing interest for LMDS systems there have been only a few commercial implementations until now especially outside of the U.S.A. The use of hierarchical structure through two-layer networking has been even rarer. In many cases LMDS systems have strong advantages against their competitors to cover the last mile. In this article, we review and analyze the standards currently available and describe the European two-layer trial system developed in 1996-2000. We show why further development towards IP based LMDS is useful in the future. Most of our recommendations are based on results derived from the European Union supported research project CABSINET. It had the aim of demonstrating the viability of a 40 GHz cellular digital television system with a return channel to offer interactive services. Two systems were tested: a line of sight link using QPSK, and a non-line of sight with COFDM modulation scheme. In the RF-subsystems, the greatest difficulty of any viable LMDS system is to obtain a moderately low price for the user receiver, while fulfilling the hard OFDM requirements in terms of phase noise, stability and spectrum restrictions. Several options have been studied in order to design the subsystems with the smallest cost. This paper will present the architectures of the transmitters, nomadic terminals, and the design of the IF/RF subsystems for both types of modulations. The discussion is focused on system engineering and selections required in order to build a full two-layer LMDS system.This work has been supported in part by European Commission through the ACTS programme (CABSINET project). PM is in part supported by the Academy of Finland (grant 50624). Authors wish to thank the CABSINET research consortium for enjoyable collaboration and useful suggestions

Study of Optical OFDM System for Wireless LAN Applications

The advantages of optical fiber make it possible to extend the data rate transmission and propagation distance. Orthogonal frequency division multiplexing (OFDM) as a multicarrier technique (MC) is used in hybrid optical-wireless system designs because it has the best spectral efficiency to radio frequency (RF) interference and lower multipath distortion. In this dissertation, a study and evaluation of optical OFDM based wireless local area network (W-LAN) systems are presented. The baseband of the OFDM signal is fully transmitted and up-converted to a radio frequency signal. Also, to reduce system costs, simple base stations (BSs) are interconnected to a central office (CO) via an optical fiber. All the required operations are achieved in the CO. The directly modulated laser (DML) and continuous wave (CW) laser are used in the system simulations as optical laser sources. Identical rectangular microstrip patch antennas have been used at the transmitter and the receiver as well. The simulations were carried out for different SMF and MMF lengths, and the variable wireless distance between the transmitting and receiving antennas was in a range of 40 dB to 80 dB. The purpose of this work is to provide a framework for integrating wireless and optical technologies in one system with the presence of OFDM technology. The required microstrip patch antenna parameters for the system are analyzed and designed. The microstrip patch antenna (S-parameters) is loaded into the Optisystem communication software tool in Touchstone format. As a result, this achievement gives a greater impetus to design an integrated optical-wireless system, and simulation results validate the proposed technique. Then, the integration of the microstrip patch antenna and optical OFDM system is achieved, and the performance is intensely studied. The entire system has been presented by developing analytical models and simulations. The system performance results are obtained regarding EIRP, SNR, signal constellations and BER. The results show that this integrated optical wireless link is very robust for carrying OFDM based wireless LAN signals over an optical fiber. Moreover, using an active patch antenna in the system helps to increase the coverage service to more than 30 meters when an SMF of 80 km length is utilized

Evaluation Of Multicarrier Air Interfaces In The Presence Of Interference For L-Band And C-Band Air-Ground Communications

The use of aeronautical vehicles and systems is continuously growing, and this means current aeronautical communication systems, particularly those operating in the very high frequency (VHF) aviation band, will suffer from severe congestion in some regions of the world. For example, it is estimated that air-to-ground (AG) communication traffic density will at least double by 2035 over that in 2012, based on the most-likely growth scenario for Europe. This traffic growth (worldwide) has led civil aviation authorities such as the FAA in the USA, and EuroControl in Europe, to jointly explore development of future communication infrastructures (FCI). According to international aviation systems policies, both current and future AG communication systems will be deployed in L-band (960-1164 MHz), and possibly in C-band (5030-5091 GHz) because of the favorable AG radio propagation characteristics in these bands. During the same time period as the FCI studies, the use of multicarrier communication technologies has become very mature for terrestrial communication systems, but for AG systems it is still being studied and tested. Aiming toward future demands, EuroControl and FAA sponsored work to define several new candidate AG radio systems with high data rate and high reliability. Dominant among these is now an L-Band Digital Aeronautical Communication Systems (L-DACS): L-DACS1. L-DACS1 is a multicarrier communication system based on the popular orthogonal frequency division multiplexing (OFDM) modulation technique. For airport surface area communication systems used in C-band, EuroControl and FAA also proposed another OFDM communication system based on the IEEE 802.16e standard, termed aeronautical mobile airport communication system (AeroMACS). This system has been proposed to provide the growing need of communication traffic in airport environments. In this dissertation, first we review existing and proposed aviation communication systems in VHF-band, L-band and C-band. We then focus our study on the use of multicarrier techniques in these aviation bands. We compare the popular and dominant multicarrier technique OFDM (which is used in cellular networks such long-term evolution (LTE) and wireless local area networks such as Wi-Fi) with the filterbank multicarrier (FBMC) technique. As far as we are aware, we are the first to propose and evaluate FBMC for aviation communication systems. We show, using analysis and computer simulations, along with measurement based (NASA) air-ground and airport surface channel models, that FBMC offers advantages in performance over the OFDM schemes. Via use of sharp filters in the frequency domain, FBMC reduces out of band interference. Specifically, it is more robust to high-power distance measurement equipment (DME) interference, and via replacement of guard bands with data-bearing subcarriers, FBMC can offer higher throughput than the contending L-DACS1 scheme, by up to 23%. Similar advantages over AeroMACS pertain in the airport surface channel. Our FBMC bit error ratio performance is comparable to that of the OFDM schemes, and is even better for our “spectrally-shaped” version of FBMC. For these improvements, FBMC requires a modest complexity increase. Our final contribution in this dissertation is the presentation of spectrally shaped FBMC (SS-FBMC). This idea allocates unequal power to subcarriers to contend with non-white noise or non-white interference. Our adaptive algorithm selects a minimum number of guard subcarriers and then allocates power accordingly to remaining subcarriers based on a “water-filling-like” approach. We are the first to propose such a cognitive radio technique with FBMC for aviation applications. Results show that SSFBMC improves over FBMC in both performance and throughput