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IEEE Communications Letters. 01/2012; 16:68-71.
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ABSTRACT: This paper proposes a bit-interleaved coded multilevel modulation for non-orthogonal cooperative transmissions. The proposed system encodes and interleaves multiple layers together, using one encoder and one interleaver, in order to average the performance of multiple layers with unequal error probabilities. The multiple layers are mapped by hierarchical symbol mapping. To improve the performance of the proposed system, the relay transmits the layers with a different hierarchical mapping pattern from the source, which is optimally derived for minimizing mean square error. To mitigate error propagation from the relay, we propose a power scaling scheme based on the error performance of the layers. The detected signals at the relay are scaled before being transmitted to the destination. A corresponding destination structure is also presented, where multiple layers can be decoupled by an iterative equalization with improved soft information. To estimate the performance of the proposed system, we develop a density evolution technique, and show that the predicted performances are consistent with simulated performances. Simulation results indicate that by using the optimal mapping pattern, power scaling, and iterative equalization with improved soft information, the proposed technique achieves both cooperative diversity and coding gains, and thus outperforms conventional cooperative schemes.
IEEE Transactions on Communications 02/2011; · 1.68 Impact Factor
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IEEE Transactions on Communications. 01/2011; 59:95-105.
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Proceedings of IEEE International Conference on Communications, ICC 2011, Kyoto, Japan, 5-9 June, 2011; 01/2011
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IEEE Transactions on Communications. 01/2010; 58:3480-3490.
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ABSTRACT: Peak-to-average power ratio (PAPR) regrowth after clipping is one disadvantage of space-frequency block coded orthogonal frequency-division multiplexing (SFBC-OFDM). In this letter, we propose an effective PAPR reduction technique of SFBC-OFDM for multinode cooperative transmission. To reduce PAPR at the source (mobile equipment), the relay applies SFBC encoding, which enables the source to transmit clipped single-input single-output (SISO)-OFDM signals without any increase of PAPR. Simulation results show that the clipped signals of proposed scheme are effectively recovered, and the proposed scheme achieves the diversity of SFBC without the complexity of multiple antennas at the source.
IEEE Signal Processing Letters 12/2009; · 1.39 Impact Factor
