LAUSR

In this paper, a novel M-ary chirp modulation scheme is proposed on the basis of the energy concentration property of chirp signals in fractional domain. In the proposed scheme, chirp signals with different phases are multiplexed in the same time-frequency bandwidth through reverse chirp-rate to increase information rate. In addition, fractional filters based on fractional Fourier transform (FRFT) are designed to separate chirp signals of different chirp-rates in the receiver. Moreover, the theoretical performance of fractional filters and the error probability of M-ary chirp system are derived. Both theoretical analysis and simulation prove that the proposed scheme outperforms M-ary quadrature amplitude modulation (QAM) system in the anti-noise performance.