Low PAPR OFDM-Based DCSK Design With Carrier Interferometry Spreading Codes

The multi-carrier aided non-coherent differential chaos shift keying (DCSK) modulated systems suffer from high peak-to-average power ratio (PAPR) due to the summations of multiple modulated signals. In this letter, we present a carrier interferometry (CI) code-aided spreading orthogonal frequency-division multiplexing-based DCSK scheme to suppress the PAPR. Instead of directly transmitting DCSK modulated signals via multiple subcarriers, in our design, each chaotic chip is spread over all available subcarriers by using CI codes, which effectively reduces the coherence among the signals, and thereby reducing PAPR. Furthermore, the theoretical PAPR and bit error rate (BER) performances are analyzed. Simulations are performed over additive white Gaussian noise, frequency selective fading, and flat fading channels. The results verify the effectiveness of our theoretical derivations, and demonstrate that the PAPR performance outperforms the counterpart schemes by exploiting the spreading CI codes, while retaining the satisfactory BER performance.