Communicación sobre lineas de suministro de energia

Informacion Tcnológica, vol. 11, nº6Proponemos un sistema para la comunicación sobre líneas de la energia eléctrica usando DS/BPSK con un régimen binario de 300 bits/s. La señal de ensanchado tiene una secuencia máxima de longitud 7 como código de “chip”, repetida 30 veces para cada dígito binario del código de la información BPSK. La sincronización entre la señal del receptor y la secuéncia PN localmente generada es obtenida por un nuevo acercamiento basado en un filtro adaptado

ANALIZA ŠUMA NA RAZDJELNIM MREŽAMA U FREKVENCIJSKOM PODRUČJU ZA ŠIROKOPOJASNI PLC, OD 10 DO 30 MHz

Prezentirani su rezultati istraživanja šuma na unutarnjim električnim distribucijskim mrežama u frekvencijskom opsegu od 10 do 30 MHz. Izmjereni podaci su obrađeni kako bi se dobile osnovne statističke karakteristike šuma. Definiran je kriterij za razgraničenje između uskopojasnih komponenti i pozadinskog šuma. Ustanovljena je korelacija između dijagrama opterećenja mreže i ukupne snage šuma u promatranom opsegu frekvencija

Investigation of broadband over power line channel capacity of shipboard power system cables for ship communications networks

Broadband over Power Line (BPL) technology has garnered significant attention lately due to recent advancements in solid state technologies and channel coding schemes. The successful application of BPL technology for in-home automation and networking has led to suggestions of applying BPL in other systems including ships. The application of BPL technology using the Shipboard Power System (SPS) as a potential communications network for ship automation systems has been proposed, to achieve recent U.S. Navy ship management concepts geared toward reducing ship manning while improving operational efficiency. This thesis presents an analytical model developed to examine the channel response characteristics and estimated throughput capacity of SPS cables. The work used a multiconductor transmission line theory based approach to model the channel response of SPS distribution lines and estimated the channel throughput capacity using a “water-filling” communication technique. This work found that BPL using the SPS holds a strong potential for use as a communications network for ship communication systems

Adaptive modulation schemes for optical wireless communication systems

High-speed wireless optical communication links have become more popular for personal mobile applications. This is a consequence of the increasing demand from the personal information service boom. Compared to the radio frequency domain, optical wireless communication offers much higher speeds and bit rates per unit power consumption. As stated by the official infrared standard IrDA optical communication enjoys much lower power consumption than Bluetooth, with an inherent security feature while in Line of Sight (LOS) applications. There are also drawbacks such as the infrared radiation cannot penetrate walls as radio frequencies do and interference from the background contribute to the channel dispersions. Focus on the modulation aspects of the optical wireless communication, this thesis try to improve the channel immunity by utilising optimised modulation to the channel. Modulation schemes such as on off keying (OOK), pulse amplitude modulation (PAM) and pulse position modulation (PPM) and pulse position and amplitude modulation PAPM schemes have been validated. The combined power and bandwidth requirements suggest that the adaptive modulation schemes can provide reliability when deployed in a real time channel, resulting in improved system performance. As a result, an adaptive modulation technique is proposed. Extensive simulations of severe noise distraction have been carried out to validate the new scheme. The simulation results indicate that the new scheme can provide increased immunity against channel noise fluctuation at a relatively low complexity. The scheme obtained formed a basis to support reliable mobile optical wireless communication applications. The adaptive scheme also takes the real time channel conditions into account, which is different from existing schemes. Guaranteed system performance can be secured without compromising power and bandwidth efficiency. This is also a new approach to realise reliable optical wireless links. Fuzzy logic control module has been developed to match the adaptive pattern

OFDM techniques for multimedia data transmission

Orthogonal Frequency Division Multiplexing (OFDM) is an efficient parallel data transmission scheme that has relatively recently become popular in both wired and wireless communication systems for the transmission of multimedia data. OFDM can be found at the core of well known systems such as digital television/radio broadcasting, ADSL internet and wireless LANs. Research into the OFDM field continually looks at different techniques to attempt to make this type of transmission more efficient. More recent works in this area have considered the benefits of using wavelet transforms in place of the Fourier transforms traditionally used in OFDM systems and other works have looked at data compression as a method of increasing throughput in these types of transmission systems. The work presented in this thesis considers the transmission of image and video data in traditional OFDM transmission and discusses the strengths and weaknesses of this method. This thesis also proposes a new type of OFDM system that combines transmission and data compression into one block. By merging these two processes into one the complexity of the system is reduced, therefore promising to increase system efficiency. The results presented in this thesis show the novel compressive OFDM method performs well in channels with a low signal-to-noise ratio. Comparisons with traditional OFDM with lossy compression show a large improvement in the quality of the data received with the new system when used in these noisy channel environments. The results also show superior results are obtained when transmitting image and video data using the new method, the high correlative properties of images are ideal for effective transmission using the new technique. The new transmission technique proposed in this thesis also gives good results when considering computation time. When compared to MATLAB simulations of a traditional DFT-based OFDM system with a separate compression block, the proposed transmission method was able to reduce the computation time by between a half to three-quarters. This decrease in computational complexity also contributes to transmission efficiency when considering the new method

Adaptive modulation schemes for optical wireless communication systems

High-speed wireless optical communication links have become more popular for personal mobile applications. This is a consequence of the increasing demand from the personal information service boom. Compared to the radio frequency domain, optical wireless communication offers much higher speeds and bit rates per unit power consumption. As stated by the official infrared standard IrDA optical communication enjoys much lower power consumption than Bluetooth, with an inherent security feature while in Line of Sight (LOS) applications. There are also drawbacks such as the infrared radiation cannot penetrate walls as radio frequencies do and interference from the background contribute to the channel dispersions. Focus on the modulation aspects of the optical wireless communication, this thesis try to improve the channel immunity by utilising optimised modulation to the channel. Modulation schemes such as on off keying (OOK), pulse amplitude modulation (PAM) and pulse position modulation (PPM) and pulse position and amplitude modulation PAPM schemes have been validated. The combined power and bandwidth requirements suggest that the adaptive modulation schemes can provide reliability when deployed in a real time channel, resulting in improved system performance. As a result, an adaptive modulation technique is proposed. Extensive simulations of severe noise distraction have been carried out to validate the new scheme. The simulation results indicate that the new scheme can provide increased immunity against channel noise fluctuation at a relatively low complexity. The scheme obtained formed a basis to support reliable mobile optical wireless communication applications. The adaptive scheme also takes the real time channel conditions into account, which is different from existing schemes. Guaranteed system performance can be secured without compromising power and bandwidth efficiency. This is also a new approach to realise reliable optical wireless links. Fuzzy logic control module has been developed to match the adaptive pattern.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Alternativas de solución al envenenamiento del Protocolo ARP en entornos LAN

En el presente artículo se presentan algunos fallos de seguridad del protocolo ARP reflejando su vulnerabilidad a diversos tipos de ataques dando lugar a fugas y/o daños de información, se han presentado diversas soluciones factibles en las cuales se encuentran S-ARP (secure ARP), ES-ARP (Secure and efficient ARP) y como alternativa de solución planteamos la creación de algoritmos que permitandetectar y mitigar ataques mediante el uso de Registros Estáticos en la Tabla ARP, como objetivo queremos resolver algunos fallos en la seguridad de ARP cambiando y mejorando los protocolos originales de este realizando las configuraciones que se creen factibles para mejorar su seguridad, en este artículo se realizará un envenenamiento ARP utilizando las herramientas VMware y GNS3 que nos permiten virtualizar un entorno real con el fin de mostrar la inseguridad que posee el protocolo ARP y así mismo implementar una alternativa económica y eficiente que mejore su seguridad