In this paper, we discuss an improved demodulation scheme using the Fractional Fourier
Transform (FrFT) for a modulation scheme employing chirp rate shift keying (CrSK).
CrSK in conjunction with the FrFT enable very high order, e.g. more than 32-ary modulation
schemes to be achievable with good bit error rate (BER) performance, even in the absence
of coding, thereby overcoming limitations of traditional schemes including phase shift
keying (PSK) or QAM (quadrature amplitude modulation). By using an FrFT-based demodulator,
we expand our demodulation degrees of freedom from a single (e.g. frequency) axis
to an entire time-frequency domain, called the Wigner Distribution (WD). We show how
the proposed demodulation scheme using the FrFT improves over past approaches by more
than 7 dB, enabling us to achieve close to 4-ary performance with a 32-ary modulation
scheme. This enables future systems to operate at 5 bits/s/Hz bandwidth efficiency,
enhancing bandwidth utilization for future generation, high data rate, applications,
such as internet.