  This paper proposes a low-complexity iterative receiver for the recently
proposed Orthogonal Chirp Division Multiplexing (OCDM) modulation scheme, where
we consider a system under frequency-selective channels and constrained to
channel state information availability only at the receiver. It has been shown
that under these assumptions, OCDM becomes an optimal waveform in terms of
performance, i.e., frame error rate (FER), when employing a receiver capable of
achieving perfect feedback equalizer (PFE) performance. Thus, this work targets
proposing such a receiver for OCDM with low-complexity. Our approach is based
on the well accepted minimum mean squared error with parallel interference
cancellation (MMSE-PIC), where we derive an approximated equalizer whose
complexity is reduced to two fast Fourier transforms (FFTs) per iteration. The
FER results reveal that i) the proposed low-complexity receiver perform as good
as the original MMSE-PIC, ii) OCDM performs very closely to PFE, and iii) OCDM
has approximately 2.5 dB improvement over OFDM.
