Home  About us  Contact
 

Transmission Channels (transmission + channel)

Distribution by Scientific Domains
Engineering50%

Selected Abstracts

CGU-frame-based representations and their connection with Reed,Solomon and DCT/DST coding schemes

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 1 2009
Fatma Abdelkefi
We investigate the use of overcomplete frame representations to correct errors occurring over burst-based transmission channels or channels leading to isolated errors. We show that when the overcomplete signal representation is based on a class of frames, called cyclic geometrically uniform (CGU) finite frames, the family of frames containing finite harmonic frames (both in and ), this representation becomes equivalent to a Reed--Solomon (RS) coding scheme. Hence, introducing an RS decoding procedure at the receiver, leads to remove the errors introduced by the transmission channel and consequently results in a quasi-perfect reconstructed signal. The advantage of this approach is to exploit the RS coding scheme without using it explicitly at the transmitter, which would lead to a robust and low complexity transmission. Furthermore, we prove that the discrete cosine transform (DCT) coding is a special case of CGU-frame-based representations and this property holds also true for the discrete sine transform (DST) coding scheme. Simulation results are presented to confirm our claims. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Devisenmarktoperationen und Informationspolitik der Europäischen Zentralbank

PERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 1 2002
Michael Frenkel
This paper analyzes the effectiveness of the foreign exchange market interventions of the European Central Bank (ECB) by studying the information policy of the ECB and examining whether the ECB relied on a specific transmission channel to influence exchange rates. Against the background of a discussion of the transmission channels through which foreign exchange market interventions of central banks may affect exchange rates, we are led to the conclusion that the information policy of the ECB was not in line with the assumptions underlying the transmission channels discussed in the theoretical literature. We argue that this finding could provide a possible explanation for the ineffectiveness of the ECB's foreign exchange market intervention in the fall of 2000. [source]

CGU-frame-based representations and their connection with Reed,Solomon and DCT/DST coding schemes

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 1 2009
Fatma Abdelkefi
We investigate the use of overcomplete frame representations to correct errors occurring over burst-based transmission channels or channels leading to isolated errors. We show that when the overcomplete signal representation is based on a class of frames, called cyclic geometrically uniform (CGU) finite frames, the family of frames containing finite harmonic frames (both in and ), this representation becomes equivalent to a Reed--Solomon (RS) coding scheme. Hence, introducing an RS decoding procedure at the receiver, leads to remove the errors introduced by the transmission channel and consequently results in a quasi-perfect reconstructed signal. The advantage of this approach is to exploit the RS coding scheme without using it explicitly at the transmitter, which would lead to a robust and low complexity transmission. Furthermore, we prove that the discrete cosine transform (DCT) coding is a special case of CGU-frame-based representations and this property holds also true for the discrete sine transform (DST) coding scheme. Simulation results are presented to confirm our claims. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Predictor-based repetitive learning control for a class of remote control nonlinear systems

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 16 2007
Ya-Jun Pan
Abstract In this paper, a repetitive learning control (RLC) approach is proposed for a class of remote control nonlinear systems satisfying the global Lipschitz condition. The proposed approach is to deal with the remote tracking control problem when the environment is periodic or repeatable over infinite time domain. Since there exist time delays in the two transmission channels: from the controller to the actuator and from the sensor to the controller, tracking a desired trajectory through a remote controller is not an easy task. In order to solve the problem caused by time delays, a predictor is designed on the controller side to predict the future state of the nonlinear system based on the delayed measurements from the sensor. The convergence of the estimation error of the predictor is ensured. The gain design of the predictor applies linear matrix inequality (LMI) techniques developed by Lyapunov Kravoskii method for time delay systems. The RLC law is constructed based on the feedback error from the predicted state. The overall tracking error tends to zero asymptotically over iterations. The proof of the stability is based on a constructed Lyapunov function related to the Lyapunov Kravoskii functional used for the proof of the predictor's convergence. By well incorporating the predictor and the RLC controller, the system state tracks the desired trajectory independent of the influence of time delays. A numerical simulation example is shown to verify the effectiveness of the proposed approach. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Devisenmarktoperationen und Informationspolitik der Europäischen Zentralbank

PERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 1 2002
Michael Frenkel
This paper analyzes the effectiveness of the foreign exchange market interventions of the European Central Bank (ECB) by studying the information policy of the ECB and examining whether the ECB relied on a specific transmission channel to influence exchange rates. Against the background of a discussion of the transmission channels through which foreign exchange market interventions of central banks may affect exchange rates, we are led to the conclusion that the information policy of the ECB was not in line with the assumptions underlying the transmission channels discussed in the theoretical literature. We argue that this finding could provide a possible explanation for the ineffectiveness of the ECB's foreign exchange market intervention in the fall of 2000. [source]

Wannier,Stark level anticrossing in biperiodic superlattices

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2006
M. Coquelin
Abstract The complex interplay of coherent and incoherent transmission channels in biased biperiodic superlattices is studied utilizing hot-electron spectroscopy. It is found that coherent transport through the superlattices is dominated by the progressive localization of the Wannier,Stark states of two subminibands. This electric field dependence is lifted at special superlattice bias conditions where anticrossings between the Wannier-Stark states of neighboring subminibands are induced. Additionally, LO-phonon mediated transmission channels open up at electric fields where the Wannier,Stark splitting between individual states exceeds the LO-phonon energy. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]