Ultra Wideband (UWB) systems are receiving recently more attention due to its approval by FCC. The systems that have been already implemented are based in analog correlation. This thesis is part of an effort to implement a wholly digital Ultra Wideband receiver. Synchronization of a signal is a first step to perform the correct demodulation of the data contained in it. It is a problem whose com...

The paper examines the implementation of QuasiOrthogonal Space-Time-Frequency Codes (QOSTFCs) to increase data rates and error performance in recently proposed STFC Multiband OFDM Ultra Wideband (MB-OFDM UWB) communications systems. It is shown that, an order-4 QOSTFC not only can provide the full rate, but also may provide significantly better error performance, compared to the conventional MB...

ii To my parents and my sister.

Article history: Available online 5 August 2009

In this experiment, wheat plants were exposed to drought stress during seed development then we worked on the obtained seeds. The seed mitochondrial ultra-structure, and antioxidant enzymes in seedling were investigated after exposure to seed accelerated ageing. Drought stress during seed development induced some changes in mitochondrial ultra-structure. Encountering seed development to drought...

In this paper, an ultra-wideband metamaterial absorber is designed and simulated. The proposed absorber is planar and low profile. It is made of a copper sheet coated with two dielectric layers. Each unit cell of the metamaterial structure is composed of multiple metallic split rings, which are patterned on the top and middle boundaries of the dielectrics. The designed absorber utilizes differe...

The effect of ultra-sonication on quality characteristics and flavor of baked eggs was studied. One hundred and twenty eggs were cooked and assigned to six treatments groups (n=20 each) that were then soaked in saline solution at various concentrations (5, 10 and 18%) with/or without further ultra-sonication treatment at 35 kHz for 1 h. The pH values were lower in the ultra-sonicated samples in...

In this paper, Multiband-OFDM UWB system based on IEEE 802.15.3a standard is studied and simulated with spatial, time and frequency (STF)coding scheme. The using of STF coding method can guarantee both full symbol rate and full diversity advantages. The simulation results show that the STF code uses multipath-rich and random-clustering characteristics of UWB channel environment on the performan...

The emergence of commercial wireless devices based on ultra-wideband radio technology (UWB-RT) is widely awaited and anticipated. UWB-RT is not only applicable to communications, imaging and ranging, it also promises to alleviate the problem of increasingly scarce spectrum resources while enabling new wireless applications and business opportunities. These prospects have caught the early attent...