The Effects of Narrowband Interference on OCDM

Orthogonal chirp division multiplexing (OCDM) is a fairly new multi-carrier modulation scheme that has been proposed for optical fiber communications. It spreads data over an entire band using a set of linear chirps that are mutually orthogonal thus achieving the maximum spectral efficiency. This paper analyzes the performance of OCDM in wireless multi-path channels with narrow band interference (NBI) and in doing so shows that linear minimum mean squared error (MMSE) equalization exhibits an interesting signal-to-noise ratio (SNR) dependent degradation in error performance caused by interference amplification at high SNR. Furthermore, it employs a variant of the MMSE equalizer when the interference energy is known to prevent interference amplification and improve the error performance.