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Straightforward Implementation (straightforward + implementation)

Distribution by Scientific Domains

Engineering	60%

Selected Abstracts

Space-time ring-TCM codes with CPM based on the decomposed model for transmission over Rayleigh fading channels

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2006
A. Pereira
Abstract Space,time (ST) coding is a proved technique for achieving high data rates in 3G mobile systems that combines coding, modulation and multiple transmitters and receivers. A novel algorithm is proposed for ST ring trellis-coded modulation (ST-RTCM) systems with continuous-phase modulation (CPM) when the channel coefficients are known to the receiver. This algorithm is based on the CPM decomposed model, which exploits the memory properties of this modulation method, resulting in a straightforward implementation of joint ST coding and CPM, which is particularly suitable for ring codes. This new scheme is used to investigate the performance of the delay diversity code with CPM over slow Rayleigh fading channels, in particular with MSK which is one of the most widely used modulation methods of continuous phase. Furthermore, a feedback version of delay diversity allowed by the decomposition is tested in 1REC and 1RC systems. This feedback configuration is seen to provide good results for low signal-to-noise ratios. Simulations results are also provided for multilevel ST-RTCM codes that achieve a higher throughput than MSK-coded systems. Additionally the serial concatenation of an outer Reed,Solomon code with an ST-RTCM code is shown, this combination further reduces the error probability and achieves even more reliable communications. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Behavioral model for reducing the complexity of mixer analysis and design

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 4 2005
A. Cidronali
Abstract This article considers an approach for the behavioral modeling of the conversion mechanism in a nonlinear device suitable for the analysis of RF/microwave mixers. The core of the model consists of the conversion matrix of the nonlinear cell under investigation, which represents its linearization around the large-signal state. This approach allows for a straightforward implementation in Computer-Aided Design (CAD) using the conversion matrix constructed from either simulation or measurements, of which the latter is considered here. Model order is significantly reduced due to the absence of the local oscillator signal in the frequency analysis plan. The intermodulation products are calculated in relative amplitude and phase and allocated in the spectrum on the basis of the conversion matrix coefficients. We illustrate the technique by implementing this model in commercial CAD software, which allows an in-depth insight into the conversion mechanism and illustrates the application to the design of a subharmonic mixer. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]

Novel down link rain fade mitigation technique for Ka-band multibeam systems

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2007
Parimal Majithiya
Abstract Rain fades at Ka-Band degrades the link quality and performance significantly. Several rain fade mitigation techniques for Ka-band satellite systems are being investigated to improve the channel capacity. Methods such as power control and adaptive waveform techniques have been proposed for use in the uplink as they are capable of straightforward implementation. A novel down link power control technique for multi-beam Ka-band system has been proposed in this paper. It is based on the use of multi-port amplifier, which is commonly used for dynamic power sharing of the beams depending upon the traffic. Payload architecture for multi-beam coverage using multi-port amplifiers has been designed for the proposed technique. The simulation results to compensate for the rain fade attenuation of one beam by sharing the unused power from other beams have been presented Copyright © 2006 John Wiley & Sons, Ltd. [source]

Analysis of Capture,Recapture Models with Individual Covariates Using Data Augmentation

BIOMETRICS, Issue 1 2009
J. Andrew Royle
Summary I consider the analysis of capture,recapture models with individual covariates that influence detection probability. Bayesian analysis of the joint likelihood is carried out using a flexible data augmentation scheme that facilitates analysis by Markov chain Monte Carlo methods, and a simple and straightforward implementation in freely available software. This approach is applied to a study of meadow voles (Microtus pennsylvanicus) in which auxiliary data on a continuous covariate (body mass) are recorded, and it is thought that detection probability is related to body mass. In a second example, the model is applied to an aerial waterfowl survey in which a double-observer protocol is used. The fundamental unit of observation is the cluster of individual birds, and the size of the cluster (a discrete covariate) is used as a covariate on detection probability. [source]

Probing Biomembrane Dynamics by Dual-Wavelength Reflection Interference Contrast Microscopy

CHEMPHYSCHEM, Issue 16 2009
Cornelia Monzel
Abstract We present an improved analysis of reflection interference contrast microscopy (RICM) images, recorded to investigate model membrane systems that mimic cell adhesion. The model systems were giant unilamellar vesicles (GUV) adhering via specific ligand,receptor interactions to supported lipid bilayers (SLB) or to patterns of receptors. Conventional RICM and dual-wavelength RICM (DW,RICM) were applied to measure absolute optical distances between the biomembranes and planar substrates. We developed algorithms for a straightforward implementation of an automated, time-resolved reconstruction of the membrane conformations from RICM/DW,RICM images, taking into account all the interfaces in the system and blurring of the data due to camera noise. Finally, we demonstrate the validity and usefulness of this new approach by analyzing the topography and fluctuations of a bound membrane in the steady state and its dynamic adaptation to osmotic pressure changes. These measurements clearly show that macroscopic membrane flow through tightly adhered area is possible in our system. [source]