Chaos based linear precoding for OFDM

This paper presents a novel multicarrier (MC) modulation method based on the linear precoded orthogonal frequency division multiplexing (LP-OFDM). For linear precoding an orthogonal transform - the orthogonalized chaotic transform (OCT), which is based on the chaotic 1-D logistic map and the Gram-Schmidt orthonormalization process, is employed. This orthogonal transform based precoding spreads information over the whole orthogonal frequency division multiplexing (OFDM) signal spectrum, therefore providing higher resistance to the multipath propagation and a lower peak-to-average power ratio (PAPR) level in comparison with a conventional OFDM system. Two types of the LP-OFDM systems are presented: with and without pilot signal precoding. For performance assessment of the newly proposed OCT-OFDM system, an LP-OFDM system based on the well-known Walsh-Hadamard transform (WHT) is used. Baseband communication system models, created using computer simulation environment, have been used in order to investigate the validity of the proposed WHT and OCT-based LP-OFDM systems with and without pilot symbol precoding. As a result, the bit error rate (BER) performance over a Relay channel for all the observed LP-OFDM system models and the conventional OFDM model are compared. In addition, the instantaneous power complementary cumulative distribution functions (CCDFs) of the waveforms, transmitted by the OFDM and the LP-OFDM systems, are explored and compared.