A Study on Quasi-orthogonal $M$-ary Chirp Modulation

This paper proposes and studies a novel M-ary chirp modulation scheme adopting quasi-orthogonal waveforms. The Symbol error probability (SEP) of M-ary modulation over Additive white Gaussian noise (AWGN) channel is derived based on coherent detection, which is a function of modulation factor and waveform period. Moreover, the SEP is investigated over a channel limited by a nominal bandwidth. Both theoretical analysis and simulations prove that the SEP performance of the proposed 8-ary chirp modulation outperforms that of conventional 8 Phase shift keying (8PSK) with the same bandwidth efficiency.