Instead of pilot tones, the impulse sample is exploited for channel estimation in Impulse Postfix OFDM systems [1]. As the magnitude of impulse sample is increased, the accuracy of channel estimation can be enhanced, but it may significantly increase the PAPR of generated OFDM symbols. In this letter, based on the statistical analysis of the generated OFDM symbol, we propose a decision scheme for determining the magnitude of impulse sample. By using the proposed scheme, we can determine the magnitude of impulse sample that provides the enhancement of BER performance as well as the avoidance of PAPR increase. The validation of the proposed scheme is demonstrated by computer simulations.
I thi leer, a witched tramo techique i preeted tht c provid th orthogoal frequecy divo mutpexng OFDM sytem wth atonal dverty gan. The pace-tme blck cdig STBC d spc-frequcy block coding SFBC r cosidrd for the trasmo of the OFDM sigals. A proper codig schme is slctd based on the estimated normalized delay spread and normalized Doler spread. The selection criterion is derived empiricay. It is shown troug computer smulatons that the proposed swtchng tchniqu can improv the bit eor rate BER performance of an OFDM system when the corresponding wireless channel has some time variation of time selectivity as well as frequency selectivity.
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