Digital Signal Processing

   

OFDM Performance Improvement Based on Active Constellation Extension and Active Interference Cancelation

Authors: SongIl Choe, IlNam Ri, SongChol Dong, IlSok Kim, ChunHo Pak

Orthogonal Frequency Division Multiplexing (OFDM) is a transceiver technology able to achieve spectrally efficient and high data rate wireless transmissions. It is also able to transmit in a non-contiguous (NC) fashion by utilizing several separate spectral whitespaces. Cognitive radio systems based on non-contiguous orthogonal frequency division multiplexing (NC-OFDM) is a promising technique that can provide efcient bandwidth utilization for high data rate wireless communication systems under frequency selective fading environments. However, the high peak to average power ratio (PAPR) and large spectrum sidelobe power are the two major limitations at the transmitter side of the NC-OFDM based Cognitive Radio (CR) system, which may significantly reduce the power efficiency and performance of the system. In this paper, we present a joint method for the PAPR reduction and sidelobe suppression based on Active Constellation Extension(ACE) and Active Interference Cancelation(AIC). The key idea of the proposed method is to dynamically extend part of the constellation points on the secondary user (SU) subcarriers based on ACE and add several SC symbols on the primary user (PU) subcarriers based on AIC to generate the appropriate cancelation signal for joint PAPR reduction and sidelobe suppression. Since the convex optimization is computationally complex in nature, a suboptimal method is also proposed whose simulation result shows that there is a significant improvement in terms of PAPR and sidelobe reduction.

Comments: 9 Pages.

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Submission history

[v1] 2018-04-16 11:37:53

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