A new concept of clipping without spectrum broadening for carrier interferometry OFDM system

This paper proposes a new technique for peak-to-average-power ratio (PAPR) reduction without spectrum broadening for Carrier Interferometry orthogonal frequency division multiplexing (CI/OFDM) system. Recently, Carrier Interferometry (CI) code is becoming an interesting code for reducing the PAPR of OFDM system. However, for guaranteeing the low PAPR as the PAPR of single carrier (i.e. by about 4-6dB with roll-of-factor of 0.2-0.5), we propose low complexity clipping technique for CI/OFDM system. However, it can be easily adapted for other OFDM systems. The main contribution of this paper is the introduction of a new clipping technique with low complexity frequency domain filtering (FDF) which is employed prior to the IFFT. The benefits of the proposed technique are low complexity of FDF and no spectrum broadening. Our results confirm that the PAPR of clipped CI/OFDM can be reduced by about 1dB better than that of the conventional clipped OFDM signals. We clarified that the PAPR is now similar to the PAPR of single carrier system. In the frequency selective fading channel, the bit-error-rate (BER) performance is also improved by about 7dB better than that of the traditional OFDM system due to the frequency diversity benefits in CI/OFDM system.