We examine adaptive equalization and diversity combining methods for fast Rayleigh-fading frequency selective channels. We assume a block adaptive receiver in which the receiver coefficients are obtained from feedforward channel estimation. For the feedforward channel estimation, we propose a novel reduced dimension channel estimation procedure, where the number of unknown parameters are reduce...

In this paper, a new deterministic subspace based blind channel estimation algorithm for doubly-selective channels is introduced. It operates on timeand frequency-shifted versions of the received sequence, and requires only two receive antennas. Furthermore, due to its deterministic nature, it needs only a short data record to work reliably. The proposed algorithm unifies and extends previously...

In this paper we propose a zero forcing (ZF) timevarying (TV) finite impulse response (FIR) equalizer for doublyselective (timeand frequency-selective) channels. We use the basis expansion model (BEM) to approximate the doubly-selective channel and to design the TV FIR equalizer. This allows us to turn a large TV problem into an equivalent small time-invariant (TIV) problem, containing only the...

This report is concerned with the characterization and study of dispersive channels. It shows how and why the physical channel distorts signals, it presents an experimental program for acquiring data to characterize the channel, and it indicates how the experimental data could be used either to evaluate the performance of arbitrary signaling techniques or to design effective signals for communi...

Recent developments in thin-film coatings for optical communication systems are reviewed. Particular emphasis is given to thin-film designs with dispersion related to the photonic crystal superprism effect. A single dispersive coating may be used for multiplexing or demultiplexing several wavelength channels by spatial beam shifting. 2004 Optical Society of America OCIS codes: (310.0310) Thin ...

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This article studies the problem of limited feedback design for heterogeneous multiuser (MU) transmissions over timeand frequency-selective (doubly selective) multiple-input multiple-output downlink channels. Under a doubly selective propagation condition, a basis expansion model (BEM) is deployed as a fitting parametric model for capturing the time-variation of the MU downlink channels and for...

The bidirectional decision feedback equalizer (DFE) performs two equalizations, one on the received signal and one on its timereversed version. In this paper, we apply the bidirectional DFE to wireless transmissions on rapidly time-varying dispersive channels and we propose an efficient implementation obtained by implementing the feedforward filter in the frequency domain. The feedback filter i...

Ultra-reliable wireless communication links require the utilization of all diversity sources of a wireless communication channel. Hadani et al. propose a two dimensional discrete symplectic Fourier transform (DSFT) as orthogonal pre-coder for a time-frequency modulations scheme. In this paper we explore general orthogonal precoding (OP) and its performance in timeand frequency-selective channel...