1. JCPEE
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  3. Volume 3, Number 1, 2013
  4. Coding technique for out-of-band power reduction of multicarrier CDMA and OFDM systems

Coding technique for out-of-band power reduction of multicarrier CDMA and OFDM systems

JCPEE.
2013;
Volume 3, Number 1
: pp. 17-24
Authors:
  1. Igor Gepko
1
Ukrainian State Centre of Radio Frequencies

In this paper, we introduce a method for out-of-band power reduction of multicarrier (MC) communication systems. Recent years MC systems possess a dominated role in wireless access owing to the ability to achieve high data rates and simultaneously high robustness to multipath and fading. Despite all advantages, MC transmission produces an essential out-of-band (OOB) interference. The OOB radiation leads to the wastage of scarce spectral resources and severe threats to adjacent wireless channels. We propose a novel technique for reducing OOB radiations in Orthogonal Frequency Division Multiplexing (OFDM) and MC Code Division Multiple Access (MC-CDMA) systems. To reduce the OOB emissions in the MC-CDMA system, we propose an analytical criterion for spectrum efficiency estimation as well as a low complexity algebraic algorithm for the proper waveform selection. The structure of selected waveform provides suppression for radiation outside the signal necessary bandwidth. Being implemented in the OFDM system, the proposed algorithm is used for the calculation of phases of cancellation carriers suppressing most powerful OOB sidelobes in a transmitted signal. In the final part of the article we consider an example of a simple precoding procedure for OFDM systems reducing the OOB power by 10 dB or more at the cost of the insignificant decrease of the information data rate.

Out-of-band emission
interference cancellation
spectrum efficiency
sidelobe suppression
MC-CDMA
OFDM.
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