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Orthogonal Frequency Division Multiplexing (OFDM) has been considered as a strong candidate for next generation high speed aerial vehicle communication systems. However, OFDM systems suffers severe performance degradation due to inter-carrier interference (ICI) in high mobility channel, if no ICI cancellation is performed. Traditionally, training symbols have been employed in one packet to help the...
Sidelobe suppression, or out-of-band emission reduction, in OFDM systems can be achieved via time-domain windowing but this may result in significantly reduced spectrum efficiency. Alternatively, sidelobe cancellation and signal predistortion techniques have been proposed for spectrum shaping, but schemes achieving a good balance between complexity and performance are yet to be developed. In this...
We propose an efficient and low-complexity scheme for estimating and compensating clipping noise in OFDMA systems. Conventional clipping noise estimation schemes, which need all demodulated data symbols, may become infeasible in OFDMA systems where a specific user may only know his own modulation scheme. The proposed scheme first uses equalized output to identify a limited number of candidate clips,...
To alleviate the high peak-to-average power ratio (PAPR), high complexity in user terminal and sensitivity to carrier frequency offset (CFO) problems in current OFDMA systems, a Quadrature OFDM (Q-OFDMA) system has been recently proposed in the single-input single-output environment. In this paper we investigate the realization of multi-input multioutput (MIMO) diversity- and capacity- oriented methods...
In precoded OFDM systems, zero-forcing (ZF) equalizers suffer from noise enhancement and error spreading problems. A minimum mean square error (MMSE) equalizer can mitigate the problems and improve system performance, however, it has relatively higher complexity and is sensitive to the estimation accuracy of noise variance. In this paper, based on the principle of reduced-rank signal processing, we...
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