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The multipath diversity and coding gain metrics for cyclic-prefixed single-carrier (SC-CP) systems, which characterize the bit error rate (BER) at high SNR, have not been carefully studied in the literature. We first show that, unlike OFDM, the diversity and coding gains for SC-CP are data-realization-dependent. Then, we show that there is a signal-to-noise ratio (SNR) threshold beyond which the dominant...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
In this paper, a low-complexity power-efficient iterative detection scheme for differentially encoded MPSK transmission over AWGN and Rayleigh fading channels is presented. As the main contribution, a novel APP coherent demodulator, which well suits for iterative processing, is derived under the optimal bit-based MAP criterion. The implementation of iteration is not trellis-based, and needn’t reconstruct...
This paper investigates the effective gain of antennas in indoor channels. A metric called instantaneous effective gain is proposed, and a multiple-cluster 3D channel model is used to facilitate the proposed antenna effective gain. In the multiple-cluster channel model, Laplacian and double exponential distribution are utilized to model azimuth and elevation signal power distribution respectively,...
Cooperative wireless communications offers a new dimension of diversity by emulating transmit antenna diversity to provide reliable communications. In cooperative diversity, single-antenna radios behave as relays between a source and destination, and the performance improvements are due to cooperation of the source and the relay. However, a misbehaving relay can degrade the envisaged performance improvements...
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...
In this paper, a novel approach using frame-based iterative channel fading parameters estimation technique from the received data sequence exploiting orthogonal property of the space-time block (STB) code is proposed. For practical implementation of STB code, the receiver requires to estimate these parameters. Regarding this type of estimation, the inherent orthogonal nature of STB code can be exploited...
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