Results 1  10
of
18
A Survey on Multicarrier Communications: Prototype Filters, Lattice Structures, and Implementation Aspects
, 2013
"... ..."
On the Szegöasymptotics for doublydispersive Gaussian channels
 Proc. IEEE Int. Symp. Information Theory
, 2011
"... ar ..."
(Show Context)
1 On the Approximate Eigenstructure of Time–Varying Channels
, 2008
"... In this article we consider the approximate description of doubly–dispersive channels by its symbol. We focus on channel operators with compactly supported spreading, which are widely used to represent fast fading multipath communication channels. The concept of approximate eigenstructure is introdu ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
(Show Context)
In this article we consider the approximate description of doubly–dispersive channels by its symbol. We focus on channel operators with compactly supported spreading, which are widely used to represent fast fading multipath communication channels. The concept of approximate eigenstructure is introduced, which measures the accuracy Ep of the approximation of the channel operation as a pure multiplication in a given Lp–norm. Two variants of such an approximate Weyl symbol calculus are studied, which have important applications in several models for time–varying mobile channels. Typically, such channels have random spreading functions (inverse Weyl transform) defined on a common support U of finite non–zero size such that approximate eigenstructure has to be measured with respect to certain norms of the spreading process. We derive several explicit relations to the size U  of the support. We show that the characterization of the ratio of Ep to some Lq–norm of the spreading function is related to weighted norms of ambiguity and Wigner functions. We present the connection to localization operators and give new bounds on the ability of localization of ambiguity functions and Wigner functions in U. Our analysis generalizes and improves recent results for the case p = 2 and q = 1.
InformationTheoretic Analysis of Underwater Acoustic OFDM Systems in Highly Dispersive Channels
, 2012
"... ..."
(Show Context)
Concise Derivation of Scattering Function from Channel Entropy Maximization
"... In order to provide a concise timevarying SISO channel model, the principle of maximum entropy is applied to scattering function derivation. The resulting model is driven by few parameters that are expressed as moments such as the channel average power or the Doppler spread. Physical interpretation ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
(Show Context)
In order to provide a concise timevarying SISO channel model, the principle of maximum entropy is applied to scattering function derivation. The resulting model is driven by few parameters that are expressed as moments such as the channel average power or the Doppler spread. Physical interpretations of the model outputs are discussed. In particular, it is shown that common Doppler spectra such as the flat or the Jakes spectrum fit well into the maximum entropy framework. The Matlab code corresponding to the proposed model is available at
Approximate Eigenstructure of LTV Channels with Compactly Supported Spreading
 Arxiv cs.IT/0701038, 2007. [Online]. Available: http://arxiv.org/abs/cs.IT/0701038
"... Abstract — In this article we obtain estimates on the approximate eigenstructure of channels with a spreading function supported only on a set of finite measure U. Because in typical application like wireless communication the spreading function is a random process corresponding to a random Hilber ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
(Show Context)
Abstract — In this article we obtain estimates on the approximate eigenstructure of channels with a spreading function supported only on a set of finite measure U. Because in typical application like wireless communication the spreading function is a random process corresponding to a random Hilbert–Schmidt channel operator H we measure this approximation in terms of the ratio of the p–norm of the deviation from variants of the Weyl symbol calculus to the a–norm of the spreading function itself. This generalizes recent results obtained for the case p = 2 and a = 1. We provide a general approach to this topic and consider then operators with U  < ∞ in more detail. We show the relation to pulse shaping and weighted norms of ambiguity functions. Finally we derive several necessary conditions on U, such that the approximation error is below certain levels. I.
3 On MaxSINR Receiver for Hexagonal Multicarrier Transmission Over Doubly Dispersive Channel
"... ar ..."
(Show Context)
Weighted Norms of Ambiguity Functions and Wigner Distributions
"... Abstract — In this article new bounds on weighted pnorms of ambiguity functions and Wigner functions are derived. Such norms occur frequently in several areas of physics and engineering. In pulse optimization for Weyl–Heisenberg signaling in widesense stationary uncorrelated scattering channels fo ..."
Abstract
 Add to MetaCart
(Show Context)
Abstract — In this article new bounds on weighted pnorms of ambiguity functions and Wigner functions are derived. Such norms occur frequently in several areas of physics and engineering. In pulse optimization for Weyl–Heisenberg signaling in widesense stationary uncorrelated scattering channels for example it is a key step to find the optimal waveforms for a given scattering statistics which is a problem also well known in radar and sonar waveform optimizations. The same situation arises in quantum information processing and optical communication when optimizing pure quantum states for communicating in bosonic quantum channels, i.e. find optimal channel input states maximizing the pure state channel fidelity. Due to the nonconvex nature of this problem the optimum and the maximizers itself are in general difficult find, numerically and analytically. Therefore upper bounds on the achievable performance are important which will be provided by this contribution. Based on a result due to E. Lieb [1], the main theorem states a new upper bound which is independent of the waveforms and becomes tight only for Gaussian weights and waveforms. A discussion of this particular important case, which tighten recent results on Gaussian quantum fidelity and coherent states, will be given. Another bound is presented for the case where scattering is determined only by some arbitrary region in phase space. I.
Pulse Shaping, Localization and the Approximate Eigenstructure of LTV Channels (Invited Paper)
"... Abstract — In this article we show the relation between the theory of pulse shaping for WSSUS channels and the notion of approximate eigenstructure for time–varying channels. We consider pulse shaping for a general signaling scheme, called Weyl–Heisenberg signaling, which includes OFDM with cyclic p ..."
Abstract
 Add to MetaCart
(Show Context)
Abstract — In this article we show the relation between the theory of pulse shaping for WSSUS channels and the notion of approximate eigenstructure for time–varying channels. We consider pulse shaping for a general signaling scheme, called Weyl–Heisenberg signaling, which includes OFDM with cyclic prefix and OFDM/OQAM. The pulse design problem in the view of optimal WSSUS–averaged SINR is an interplay between localization and ”orthogonality”. The localization problem itself can be expressed in terms of eigenvalues of localization operators and is intimately connected to the concept of approximate eigenstructure of LTV channel operators. In fact, on the L2–level both are equivalent as we will show. The concept of ”orthogonality ” in turn can be related to notion of tight frames. The right balance between these two sides is still an open problem. However, several statements on achievable values of certain localization measures and fundamental limits on SINR can already be made as will be shown in the paper. I.