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Maximum likelihood detection for VBLAST architectures is equivalent to an integer quadratic optimization problem. Branch and bound (BB) algorithm is a simple method for solving quadratic problem, though other methods exist. In this paper, we use a depth-first BB algorithm for VBLAST detection. For reducing detection complexity, we use a preprocessing stage before running the BB algorithm. We also...
With availability of channel state information (CSI) at the transmitter and receiver, we can use UCD channel decomposition method for obtaining identical channel conditions for all layers in a VBLAST architecture. This leads to better performance than conventional SQRD VBLAST without need to layer ordering priori to detection. In this paper, we use UCD technique for iterative VBLAST detection and...
Sea clutter is the backscattered returns from a patch of sea surface illuminated by a radar pulse and it's one of difficult domains in radar clutter modeling. A lot of efforts have been made to fit various distributions to the observed amplitude data of sea clutter. However, the fitting of those distributions to real sea clutter data is not good, and using parameters estimated from those distributions...
High peak-to-average power ratio (PAPR) of transmitted signals is a major drawback for multi-carrier modulation (MCM) systems such as orthogonal frequency division multiplexing (OFDM) and wavelet packet division multiplexing (WPDM). Companding transform is an efficient and simple method to reduce the PAPR for MCM systems. In this paper, a novel adaptive companding transform scheme is proposed to efficaciously...
Multicarrier modulation (MCM) technique is considered as the key element in realizing high-speed wireless and wireline digital communications. However, high peak-to-average power ratio (PAPR) of transmitted signals is a major drawback for multicarrier modulation systems such as orthogonal frequency division multiplexing (OFDM) and wavelet packet division multiplexing (WPDM). This paper investigates...
This paper presents the application of Orthogonal frequency domain modulation-Continuous Phase Modulation (OFDM-CPM) in multipath Standard University Interim (SUI) channels. It is shown that, in addition to OdB Peak to Average Power Ratio (PAPR) and power efficiency, uncoded OFDM-CPM exploits the frequency diversity of multipath channel. Taking into account the Input Power Backoff (IBO), OFDM-CPM...
The power network has the advantage of being an independent communications network where existing cable infrastructure can be used for dual purpose. Eavesdropping is thus easily done with a simple radio receiver placed in the vicinity of the power line. An adaptive secure turbo coded OFDM scheme is suggested for PLC due to its security and error correction capability and its high speed.
In recent years many speech enhancement methods are based on stochastic models. In contrast with most recently models, we do not consider that DFT coefficients may be modeled just by complex Gaussian, Laplacian or Gamma density and stochastic character. We model the DFT coefficients by T location-scale distribution. Then we derive a new MMSE estimator which relies on stochastic-deterministic model...
Sphere decoding algorithm (SDA) is a computationally efficient way for maximum likelihood detection in various lattice decoding problems. The main unsolved problem in SDA is initial radius selection. In this paper a new accelerated version of Viterbo-Boutros SDA is devised in which large initial radius selection, does not sacrifice the decoding speed of sphere decoder. In the new proposed method,...
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