Multiple Chirp-Rate Modulation Based on Fractional Fourier Transform

A novel modulation scheme called Multiple Chirp-rate-Shift Keying (MCrSK) is proposed, which uses different chirp-rates to represent symbols. Due to the Fractional Fourier Transform (FrFT) properties of the chirp signals, a noncoherent demodulation method of MCrSK based on FrFT is available. Results of simulation indicate that MCrSK acquires better Bit Error Rate (BER) performance than MPSK in higher modulation order cases and better power efficiency than MQAM due to its constant envelope property. Further, keying of central frequencies of chirp signal can also be utilized with MCrSK to achieve a hybrid modulation, providing diverse trade-off ways between BER and spectrum efficiency.