New interleaving scheme for CE-OFDM systems using chaotic maps

Continuous phase modulation (CPM) is an attractive scheme for wireless communications because of its constant envelope(CE) and its ability to improve the diversity of the multipath channel. In this paper we propose a new interleaving scheme for the CPM based orthogonal frequency-division multiplexing (CE-OFDM) system, namely chaotic interleaving. The proposed system combines the key characteristics of CE-OFDM and the chaotic maps. Thus, this new system gets the advantages of power efficiency of CE-OFDM and the performance improvement of the chaotic interleaving. The proposed system comprises frequency domain equalization (FDE) to obtain high diversity gains over frequency selective multipath fading channels. The bit error rate (BER) performance of the CE-OFDM system with and without chaotic interleaving is evaluated by computer simulations. The simulation results show that, the CE-OFDM system based on the new interleaving scheme provides a better performance of about 2.3 dB improvements in SNR than the conventional CE-OFDM system.