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Considering orthogonal frequency division multiplexing (OFDM) transmissions, we derive analytical expressions for the Cramer-Rao bounds for the subcarrier signal-to-noise ratio (SNR) estimates. The channel coefficients of the different subcarriers are assumed to be constant over the observation interval and the received signal is assumed to be corrupted by additive white Gaussian noise (AWGN). We...
We propose a new technique to estimate the signal-to-noise ratio (SNR) over flat fading time-varying single-input multiple-output (SIMO) channels, for quadrature amplitude modulation (QAM) signals in complex additive white Gaussian noise (AWGN). This technique relies on the use of periodically transmitted pilot symbols in the estimation process. It is a decision directed (DD) procedure since detected...
The impulsive interferences are not negligible in many communication channels, such as power line channels. During the initialization of Turbo iterative decode algorithm, e.g., message passing algorithm for Low-Density Parity-Check code's decoder, it is necessary to estimate parameters of channel to retrieve the prior information from the received signals. Performances of the detector/estimator based...
The problem of signal-to-noise ratio (SNR) estimation over time-varying flat fading single-input multiple-output (SIMO) channels, for non constant envelope signals, is addressed in this article when the signal is corrupted by complex additive white Gaussian noise (AWGN). It is based on the use of periodically transmitted pilot symbols to facilitate the estimation process. It relies also on the detection...
In order to retrieve the pre-estimated information from the received signals, it is necessary to estimate the variance of AWGN channel during the initialization of Turbo iterative decoder. Some literature has been devoted to this problem in BPSK/8PSK scenarios, and in this paper, we present another low-complexity blind SNR estimation method based on empirical characteristic functionpsilas derivative...
Li and Xia have recently investigated the design of space-time codes that achieve full spatial diversity for asynchronous cooperative communications. They show that certain of the binary space-time trellis codes derived from the Hammons-El Gamal stacking construction are delay tolerant and can be used in the multilevel code constructions by Lu and Kumar to produce delay tolerant space-time codes for...
In this paper, we propose a cognitive radio-based multi-user resource allocation framework for mobile ad hoc networks using multi-carrier DS CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, in addition to potential narrow-band interference, a channel sensing and estimation mechanism is provided...
This paper deals with the goodness of the Gaussian assumption when designing second-order blind estimation methods in the context of digital communications. The low- and high-signal-to-noise ratio (SNR) asymptotic performance of the maximum likelihood estimator - derived assuming Gaussian transmitted symbols - is compared with the performance of the optimal second-order estimator, which exploits the...
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